linux - kernel/workqueue.c

8058 lines · 225.3 KiB

1	// SPDX-License-Identifier: GPL-2.0-only
2	/*
3	* kernel/workqueue.c - generic async execution with shared worker pool
4	*
5	* Copyright (C) 2002 Ingo Molnar
6	*
7	* Derived from the taskqueue/keventd code by:
8	* David Woodhouse <[email protected]>
9	* Andrew Morton
10	* Kai Petzke <[email protected]>
11	* Theodore Ts'o <[email protected]>
12	*
13	* Made to use alloc_percpu by Christoph Lameter.
14	*
15	* Copyright (C) 2010 SUSE Linux Products GmbH
16	* Copyright (C) 2010 Tejun Heo <[email protected]>
17	*
18	* This is the generic async execution mechanism. Work items as are
19	* executed in process context. The worker pool is shared and
20	* automatically managed. There are two worker pools for each CPU (one for
21	* normal work items and the other for high priority ones) and some extra
22	* pools for workqueues which are not bound to any specific CPU - the
23	* number of these backing pools is dynamic.
24	*
25	* Please read Documentation/core-api/workqueue.rst for details.
26	*/
27
28	#include <linux/export.h>
29	#include <linux/kernel.h>
30	#include <linux/sched.h>
31	#include <linux/init.h>
32	#include <linux/interrupt.h>
33	#include <linux/signal.h>
34	#include <linux/completion.h>
35	#include <linux/workqueue.h>
36	#include <linux/slab.h>
37	#include <linux/cpu.h>
38	#include <linux/notifier.h>
39	#include <linux/kthread.h>
40	#include <linux/hardirq.h>
41	#include <linux/mempolicy.h>
42	#include <linux/freezer.h>
43	#include <linux/debug_locks.h>
44	#include <linux/lockdep.h>
45	#include <linux/idr.h>
46	#include <linux/jhash.h>
47	#include <linux/hashtable.h>
48	#include <linux/rculist.h>
49	#include <linux/nodemask.h>
50	#include <linux/moduleparam.h>
51	#include <linux/uaccess.h>
52	#include <linux/sched/isolation.h>
53	#include <linux/sched/debug.h>
54	#include <linux/nmi.h>
55	#include <linux/kvm_para.h>
56	#include <linux/delay.h>
57	#include <linux/irq_work.h>
58
59	#include "workqueue_internal.h"
60
61	enum worker_pool_flags {
62	/*
63	* worker_pool flags
64	*
65	* A bound pool is either associated or disassociated with its CPU.
66	* While associated (!DISASSOCIATED), all workers are bound to the
67	* CPU and none has %WORKER_UNBOUND set and concurrency management
68	* is in effect.
69	*
70	* While DISASSOCIATED, the cpu may be offline and all workers have
71	* %WORKER_UNBOUND set and concurrency management disabled, and may
72	* be executing on any CPU. The pool behaves as an unbound one.
73	*
74	* Note that DISASSOCIATED should be flipped only while holding
75	* wq_pool_attach_mutex to avoid changing binding state while
76	* worker_attach_to_pool() is in progress.
77	*
78	* As there can only be one concurrent BH execution context per CPU, a
79	* BH pool is per-CPU and always DISASSOCIATED.
80	*/
81	POOL_BH = 1 << 0, /* is a BH pool */
82	POOL_MANAGER_ACTIVE = 1 << 1, /* being managed */
83	POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
84	POOL_BH_DRAINING = 1 << 3, /* draining after CPU offline */
85	};
86
87	enum worker_flags {
88	/* worker flags */
89	WORKER_DIE = 1 << 1, /* die die die */
90	WORKER_IDLE = 1 << 2, /* is idle */
91	WORKER_PREP = 1 << 3, /* preparing to run works */
92	WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
93	WORKER_UNBOUND = 1 << 7, /* worker is unbound */
94	WORKER_REBOUND = 1 << 8, /* worker was rebound */
95
96	WORKER_NOT_RUNNING = WORKER_PREP \| WORKER_CPU_INTENSIVE \|
97	WORKER_UNBOUND \| WORKER_REBOUND,
98	};
99
100	enum work_cancel_flags {
101	WORK_CANCEL_DELAYED = 1 << 0, /* canceling a delayed_work */
102	WORK_CANCEL_DISABLE = 1 << 1, /* canceling to disable */
103	};
104
105	enum wq_internal_consts {
106	NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */
107
108	UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */
109	BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
110
111	MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
112	IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
113
114	MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2,
115	/* call for help after 10ms
116	(min two ticks) */
117	MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
118	CREATE_COOLDOWN = HZ, /* time to breath after fail */
119
120	/*
121	* Rescue workers are used only on emergencies and shared by
122	* all cpus. Give MIN_NICE.
123	*/
124	RESCUER_NICE_LEVEL = MIN_NICE,
125	HIGHPRI_NICE_LEVEL = MIN_NICE,
126
127	WQ_NAME_LEN = 32,
128	WORKER_ID_LEN = 10 + WQ_NAME_LEN, /* "kworker/R-" + WQ_NAME_LEN */
129	};
130
131	/*
132	* We don't want to trap softirq for too long. See MAX_SOFTIRQ_TIME and
133	* MAX_SOFTIRQ_RESTART in kernel/softirq.c. These are macros because
134	* msecs_to_jiffies() can't be an initializer.
135	*/
136	#define BH_WORKER_JIFFIES msecs_to_jiffies(2)
137	#define BH_WORKER_RESTARTS 10
138
139	/*
140	* Structure fields follow one of the following exclusion rules.
141	*
142	* I: Modifiable by initialization/destruction paths and read-only for
143	* everyone else.
144	*
145	* P: Preemption protected. Disabling preemption is enough and should
146	* only be modified and accessed from the local cpu.
147	*
148	* L: pool->lock protected. Access with pool->lock held.
149	*
150	* LN: pool->lock and wq_node_nr_active->lock protected for writes. Either for
151	* reads.
152	*
153	* K: Only modified by worker while holding pool->lock. Can be safely read by
154	* self, while holding pool->lock or from IRQ context if %current is the
155	* kworker.
156	*
157	* S: Only modified by worker self.
158	*
159	* A: wq_pool_attach_mutex protected.
160	*
161	* PL: wq_pool_mutex protected.
162	*
163	* PR: wq_pool_mutex protected for writes. RCU protected for reads.
164	*
165	* PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads.
166	*
167	* PWR: wq_pool_mutex and wq->mutex protected for writes. Either or
168	* RCU for reads.
169	*
170	* WQ: wq->mutex protected.
171	*
172	* WR: wq->mutex protected for writes. RCU protected for reads.
173	*
174	* WO: wq->mutex protected for writes. Updated with WRITE_ONCE() and can be read
175	* with READ_ONCE() without locking.
176	*
177	* MD: wq_mayday_lock protected.
178	*
179	* WD: Used internally by the watchdog.
180	*/
181
182	/* struct worker is defined in workqueue_internal.h */
183
184	struct worker_pool {
185	raw_spinlock_t lock; /* the pool lock */
186	int cpu; /* I: the associated cpu */
187	int node; /* I: the associated node ID */
188	int id; /* I: pool ID */
189	unsigned int flags; /* L: flags */
190
191	unsigned long watchdog_ts; /* L: watchdog timestamp */
192	bool cpu_stall; /* WD: stalled cpu bound pool */
193
194	/*
195	* The counter is incremented in a process context on the associated CPU
196	* w/ preemption disabled, and decremented or reset in the same context
197	* but w/ pool->lock held. The readers grab pool->lock and are
198	* guaranteed to see if the counter reached zero.
199	*/
200	int nr_running;
201
202	struct list_head worklist; /* L: list of pending works */
203
204	int nr_workers; /* L: total number of workers */
205	int nr_idle; /* L: currently idle workers */
206
207	struct list_head idle_list; /* L: list of idle workers */
208	struct timer_list idle_timer; /* L: worker idle timeout */
209	struct work_struct idle_cull_work; /* L: worker idle cleanup */
210
211	struct timer_list mayday_timer; /* L: SOS timer for workers */
212
213	/* a workers is either on busy_hash or idle_list, or the manager */
214	DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
215	/* L: hash of busy workers */
216
217	struct worker manager; / L: purely informational */
218	struct list_head workers; /* A: attached workers */
219
220	struct ida worker_ida; /* worker IDs for task name */
221
222	struct workqueue_attrs attrs; / I: worker attributes */
223	struct hlist_node hash_node; /* PL: unbound_pool_hash node */
224	int refcnt; /* PL: refcnt for unbound pools */
225
226	/*
227	* Destruction of pool is RCU protected to allow dereferences
228	* from get_work_pool().
229	*/
230	struct rcu_head rcu;
231	};
232
233	/*
234	* Per-pool_workqueue statistics. These can be monitored using
235	* tools/workqueue/wq_monitor.py.
236	*/
237	enum pool_workqueue_stats {
238	PWQ_STAT_STARTED, /* work items started execution */
239	PWQ_STAT_COMPLETED, /* work items completed execution */
240	PWQ_STAT_CPU_TIME, /* total CPU time consumed */
241	PWQ_STAT_CPU_INTENSIVE, /* wq_cpu_intensive_thresh_us violations */
242	PWQ_STAT_CM_WAKEUP, /* concurrency-management worker wakeups */
243	PWQ_STAT_REPATRIATED, /* unbound workers brought back into scope */
244	PWQ_STAT_MAYDAY, /* maydays to rescuer */
245	PWQ_STAT_RESCUED, /* linked work items executed by rescuer */
246
247	PWQ_NR_STATS,
248	};
249
250	/*
251	* The per-pool workqueue. While queued, bits below WORK_PWQ_SHIFT
252	* of work_struct->data are used for flags and the remaining high bits
253	* point to the pwq; thus, pwqs need to be aligned at two's power of the
254	* number of flag bits.
255	*/
256	struct pool_workqueue {
257	struct worker_pool pool; / I: the associated pool */
258	struct workqueue_struct wq; / I: the owning workqueue */
259	int work_color; /* L: current color */
260	int flush_color; /* L: flushing color */
261	int refcnt; /* L: reference count */
262	int nr_in_flight[WORK_NR_COLORS];
263	/* L: nr of in_flight works */
264	bool plugged; /* L: execution suspended */
265
266	/*
267	* nr_active management and WORK_STRUCT_INACTIVE:
268	*
269	* When pwq->nr_active >= max_active, new work item is queued to
270	* pwq->inactive_works instead of pool->worklist and marked with
271	* WORK_STRUCT_INACTIVE.
272	*
273	* All work items marked with WORK_STRUCT_INACTIVE do not participate in
274	* nr_active and all work items in pwq->inactive_works are marked with
275	* WORK_STRUCT_INACTIVE. But not all WORK_STRUCT_INACTIVE work items are
276	* in pwq->inactive_works. Some of them are ready to run in
277	* pool->worklist or worker->scheduled. Those work itmes are only struct
278	* wq_barrier which is used for flush_work() and should not participate
279	* in nr_active. For non-barrier work item, it is marked with
280	* WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works.
281	*/
282	int nr_active; /* L: nr of active works */
283	struct list_head inactive_works; /* L: inactive works */
284	struct list_head pending_node; /* LN: node on wq_node_nr_active->pending_pwqs */
285	struct list_head pwqs_node; /* WR: node on wq->pwqs */
286	struct list_head mayday_node; /* MD: node on wq->maydays */
287
288	u64 stats[PWQ_NR_STATS];
289
290	/*
291	* Release of unbound pwq is punted to a kthread_worker. See put_pwq()
292	* and pwq_release_workfn() for details. pool_workqueue itself is also
293	* RCU protected so that the first pwq can be determined without
294	* grabbing wq->mutex.
295	*/
296	struct kthread_work release_work;
297	struct rcu_head rcu;
298	} __aligned(1 << WORK_STRUCT_PWQ_SHIFT);
299
300	/*
301	* Structure used to wait for workqueue flush.
302	*/
303	struct wq_flusher {
304	struct list_head list; /* WQ: list of flushers */
305	int flush_color; /* WQ: flush color waiting for */
306	struct completion done; /* flush completion */
307	};
308
309	struct wq_device;
310
311	/*
312	* Unlike in a per-cpu workqueue where max_active limits its concurrency level
313	* on each CPU, in an unbound workqueue, max_active applies to the whole system.
314	* As sharing a single nr_active across multiple sockets can be very expensive,
315	* the counting and enforcement is per NUMA node.
316	*
317	* The following struct is used to enforce per-node max_active. When a pwq wants
318	* to start executing a work item, it should increment ->nr using
319	* tryinc_node_nr_active(). If acquisition fails due to ->nr already being over
320	* ->max, the pwq is queued on ->pending_pwqs. As in-flight work items finish
321	* and decrement ->nr, node_activate_pending_pwq() activates the pending pwqs in
322	* round-robin order.
323	*/
324	struct wq_node_nr_active {
325	int max; /* per-node max_active */
326	atomic_t nr; /* per-node nr_active */
327	raw_spinlock_t lock; /* nests inside pool locks */
328	struct list_head pending_pwqs; /* LN: pwqs with inactive works */
329	};
330
331	/*
332	* The externally visible workqueue. It relays the issued work items to
333	* the appropriate worker_pool through its pool_workqueues.
334	*/
335	struct workqueue_struct {
336	struct list_head pwqs; /* WR: all pwqs of this wq */
337	struct list_head list; /* PR: list of all workqueues */
338
339	struct mutex mutex; /* protects this wq */
340	int work_color; /* WQ: current work color */
341	int flush_color; /* WQ: current flush color */
342	atomic_t nr_pwqs_to_flush; /* flush in progress */
343	struct wq_flusher first_flusher; / WQ: first flusher */
344	struct list_head flusher_queue; /* WQ: flush waiters */
345	struct list_head flusher_overflow; /* WQ: flush overflow list */
346
347	struct list_head maydays; /* MD: pwqs requesting rescue */
348	struct worker rescuer; / MD: rescue worker */
349
350	int nr_drainers; /* WQ: drain in progress */
351
352	/* See alloc_workqueue() function comment for info on min/max_active */
353	int max_active; /* WO: max active works */
354	int min_active; /* WO: min active works */
355	int saved_max_active; /* WQ: saved max_active */
356	int saved_min_active; /* WQ: saved min_active */
357
358	struct workqueue_attrs unbound_attrs; / PW: only for unbound wqs */
359	struct pool_workqueue __rcu dfl_pwq; / PW: only for unbound wqs */
360
361	#ifdef CONFIG_SYSFS
362	struct wq_device wq_dev; / I: for sysfs interface */
363	#endif
364	#ifdef CONFIG_LOCKDEP
365	char *lock_name;
366	struct lock_class_key key;
367	struct lockdep_map __lockdep_map;
368	struct lockdep_map *lockdep_map;
369	#endif
370	char name[WQ_NAME_LEN]; /* I: workqueue name */
371
372	/*
373	* Destruction of workqueue_struct is RCU protected to allow walking
374	* the workqueues list without grabbing wq_pool_mutex.
375	* This is used to dump all workqueues from sysrq.
376	*/
377	struct rcu_head rcu;
378
379	/* hot fields used during command issue, aligned to cacheline */
380	unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */
381	struct pool_workqueue __rcu * __percpu cpu_pwq; / I: per-cpu pwqs */
382	struct wq_node_nr_active node_nr_active[]; / I: per-node nr_active */
383	};
384
385	/*
386	* Each pod type describes how CPUs should be grouped for unbound workqueues.
387	* See the comment above workqueue_attrs->affn_scope.
388	*/
389	struct wq_pod_type {
390	int nr_pods; /* number of pods */
391	cpumask_var_t pod_cpus; / pod -> cpus */
392	int pod_node; / pod -> node */
393	int cpu_pod; / cpu -> pod */
394	};
395
396	struct work_offq_data {
397	u32 pool_id;
398	u32 disable;
399	u32 flags;
400	};
401
402	static const char *wq_affn_names[WQ_AFFN_NR_TYPES] = {
403	[WQ_AFFN_DFL] = "default",
404	[WQ_AFFN_CPU] = "cpu",
405	[WQ_AFFN_SMT] = "smt",
406	[WQ_AFFN_CACHE] = "cache",
407	[WQ_AFFN_NUMA] = "numa",
408	[WQ_AFFN_SYSTEM] = "system",
409	};
410
411	/*
412	* Per-cpu work items which run for longer than the following threshold are
413	* automatically considered CPU intensive and excluded from concurrency
414	* management to prevent them from noticeably delaying other per-cpu work items.
415	* ULONG_MAX indicates that the user hasn't overridden it with a boot parameter.
416	* The actual value is initialized in wq_cpu_intensive_thresh_init().
417	*/
418	static unsigned long wq_cpu_intensive_thresh_us = ULONG_MAX;
419	module_param_named(cpu_intensive_thresh_us, wq_cpu_intensive_thresh_us, ulong, 0644);
420	#ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT
421	static unsigned int wq_cpu_intensive_warning_thresh = 4;
422	module_param_named(cpu_intensive_warning_thresh, wq_cpu_intensive_warning_thresh, uint, 0644);
423	#endif
424
425	/* see the comment above the definition of WQ_POWER_EFFICIENT */
426	static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT);
427	module_param_named(power_efficient, wq_power_efficient, bool, 0444);
428
429	static bool wq_online; /* can kworkers be created yet? */
430	static bool wq_topo_initialized __read_mostly = false;
431
432	static struct kmem_cache *pwq_cache;
433
434	static struct wq_pod_type wq_pod_types[WQ_AFFN_NR_TYPES];
435	static enum wq_affn_scope wq_affn_dfl = WQ_AFFN_CACHE;
436
437	/* buf for wq_update_unbound_pod_attrs(), protected by CPU hotplug exclusion */
438	static struct workqueue_attrs *unbound_wq_update_pwq_attrs_buf;
439
440	static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */
441	static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */
442	static DEFINE_RAW_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
443	/* wait for manager to go away */
444	static struct rcuwait manager_wait = __RCUWAIT_INITIALIZER(manager_wait);
445
446	static LIST_HEAD(workqueues); /* PR: list of all workqueues */
447	static bool workqueue_freezing; /* PL: have wqs started freezing? */
448
449	/* PL: mirror the cpu_online_mask excluding the CPU in the midst of hotplugging */
450	static cpumask_var_t wq_online_cpumask;
451
452	/* PL&A: allowable cpus for unbound wqs and work items */
453	static cpumask_var_t wq_unbound_cpumask;
454
455	/* PL: user requested unbound cpumask via sysfs */
456	static cpumask_var_t wq_requested_unbound_cpumask;
457
458	/* PL: isolated cpumask to be excluded from unbound cpumask */
459	static cpumask_var_t wq_isolated_cpumask;
460
461	/* for further constrain wq_unbound_cpumask by cmdline parameter*/
462	static struct cpumask wq_cmdline_cpumask __initdata;
463
464	/* CPU where unbound work was last round robin scheduled from this CPU */
465	static DEFINE_PER_CPU(int, wq_rr_cpu_last);
466
467	/*
468	* Local execution of unbound work items is no longer guaranteed. The
469	* following always forces round-robin CPU selection on unbound work items
470	* to uncover usages which depend on it.
471	*/
472	#ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU
473	static bool wq_debug_force_rr_cpu = true;
474	#else
475	static bool wq_debug_force_rr_cpu = false;
476	#endif
477	module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644);
478
479	/* to raise softirq for the BH worker pools on other CPUs */
480	static DEFINE_PER_CPU_SHARED_ALIGNED(struct irq_work [NR_STD_WORKER_POOLS], bh_pool_irq_works);
481
482	/* the BH worker pools */
483	static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], bh_worker_pools);
484
485	/* the per-cpu worker pools */
486	static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools);
487
488	static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */
489
490	/* PL: hash of all unbound pools keyed by pool->attrs */
491	static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER);
492
493	/* I: attributes used when instantiating standard unbound pools on demand */
494	static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS];
495
496	/* I: attributes used when instantiating ordered pools on demand */
497	static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS];
498
499	/*
500	* I: kthread_worker to release pwq's. pwq release needs to be bounced to a
501	* process context while holding a pool lock. Bounce to a dedicated kthread
502	* worker to avoid A-A deadlocks.
503	*/
504	static struct kthread_worker *pwq_release_worker __ro_after_init;
505
506	struct workqueue_struct *system_wq __ro_after_init;
507	EXPORT_SYMBOL(system_wq);
508	struct workqueue_struct *system_highpri_wq __ro_after_init;
509	EXPORT_SYMBOL_GPL(system_highpri_wq);
510	struct workqueue_struct *system_long_wq __ro_after_init;
511	EXPORT_SYMBOL_GPL(system_long_wq);
512	struct workqueue_struct *system_unbound_wq __ro_after_init;
513	EXPORT_SYMBOL_GPL(system_unbound_wq);
514	struct workqueue_struct *system_freezable_wq __ro_after_init;
515	EXPORT_SYMBOL_GPL(system_freezable_wq);
516	struct workqueue_struct *system_power_efficient_wq __ro_after_init;
517	EXPORT_SYMBOL_GPL(system_power_efficient_wq);
518	struct workqueue_struct *system_freezable_power_efficient_wq __ro_after_init;
519	EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq);
520	struct workqueue_struct *system_bh_wq;
521	EXPORT_SYMBOL_GPL(system_bh_wq);
522	struct workqueue_struct *system_bh_highpri_wq;
523	EXPORT_SYMBOL_GPL(system_bh_highpri_wq);
524
525	static int worker_thread(void *__worker);
526	static void workqueue_sysfs_unregister(struct workqueue_struct *wq);
527	static void show_pwq(struct pool_workqueue *pwq);
528	static void show_one_worker_pool(struct worker_pool *pool);
529
530	#define CREATE_TRACE_POINTS
531	#include <trace/events/workqueue.h>
532
533	#define assert_rcu_or_pool_mutex() \
534	RCU_LOCKDEP_WARN(!rcu_read_lock_any_held() && \
535	!lockdep_is_held(&wq_pool_mutex), \
536	"RCU or wq_pool_mutex should be held")
537
538	#define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \
539	RCU_LOCKDEP_WARN(!rcu_read_lock_any_held() && \
540	!lockdep_is_held(&wq->mutex) && \
541	!lockdep_is_held(&wq_pool_mutex), \
542	"RCU, wq->mutex or wq_pool_mutex should be held")
543
544	#define for_each_bh_worker_pool(pool, cpu) \
545	for ((pool) = &per_cpu(bh_worker_pools, cpu)[0]; \
546	(pool) < &per_cpu(bh_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
547	(pool)++)
548
549	#define for_each_cpu_worker_pool(pool, cpu) \
550	for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
551	(pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
552	(pool)++)
553
554	/**
555	* for_each_pool - iterate through all worker_pools in the system
556	* @pool: iteration cursor
557	* @pi: integer used for iteration
558	*
559	* This must be called either with wq_pool_mutex held or RCU read
560	* locked. If the pool needs to be used beyond the locking in effect, the
561	* caller is responsible for guaranteeing that the pool stays online.
562	*
563	* The if/else clause exists only for the lockdep assertion and can be
564	* ignored.
565	*/
566	#define for_each_pool(pool, pi) \
567	idr_for_each_entry(&worker_pool_idr, pool, pi) \
568	if (({ assert_rcu_or_pool_mutex(); false; })) { } \
569	else
570
571	/**
572	* for_each_pool_worker - iterate through all workers of a worker_pool
573	* @worker: iteration cursor
574	* @pool: worker_pool to iterate workers of
575	*
576	* This must be called with wq_pool_attach_mutex.
577	*
578	* The if/else clause exists only for the lockdep assertion and can be
579	* ignored.
580	*/
581	#define for_each_pool_worker(worker, pool) \
582	list_for_each_entry((worker), &(pool)->workers, node) \
583	if (({ lockdep_assert_held(&wq_pool_attach_mutex); false; })) { } \
584	else
585
586	/**
587	* for_each_pwq - iterate through all pool_workqueues of the specified workqueue
588	* @pwq: iteration cursor
589	* @wq: the target workqueue
590	*
591	* This must be called either with wq->mutex held or RCU read locked.
592	* If the pwq needs to be used beyond the locking in effect, the caller is
593	* responsible for guaranteeing that the pwq stays online.
594	*
595	* The if/else clause exists only for the lockdep assertion and can be
596	* ignored.
597	*/
598	#define for_each_pwq(pwq, wq) \
599	list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node, \
600	lockdep_is_held(&(wq->mutex)))
601
602	#ifdef CONFIG_DEBUG_OBJECTS_WORK
603
604	static const struct debug_obj_descr work_debug_descr;
605
606	static void work_debug_hint(void addr)
607	{
608	return ((struct work_struct *) addr)->func;
609	}
610
611	static bool work_is_static_object(void *addr)
612	{
613	struct work_struct *work = addr;
614
615	return test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work));
616	}
617
618	/*
619	* fixup_init is called when:
620	* - an active object is initialized
621	*/
622	static bool work_fixup_init(void *addr, enum debug_obj_state state)
623	{
624	struct work_struct *work = addr;
625
626	switch (state) {
627	case ODEBUG_STATE_ACTIVE:
628	cancel_work_sync(work);
629	debug_object_init(work, &work_debug_descr);
630	return true;
631	default:
632	return false;
633	}
634	}
635
636	/*
637	* fixup_free is called when:
638	* - an active object is freed
639	*/
640	static bool work_fixup_free(void *addr, enum debug_obj_state state)
641	{
642	struct work_struct *work = addr;
643
644	switch (state) {
645	case ODEBUG_STATE_ACTIVE:
646	cancel_work_sync(work);
647	debug_object_free(work, &work_debug_descr);
648	return true;
649	default:
650	return false;
651	}
652	}
653
654	static const struct debug_obj_descr work_debug_descr = {
655	.name = "work_struct",
656	.debug_hint = work_debug_hint,
657	.is_static_object = work_is_static_object,
658	.fixup_init = work_fixup_init,
659	.fixup_free = work_fixup_free,
660	};
661
662	static inline void debug_work_activate(struct work_struct *work)
663	{
664	debug_object_activate(work, &work_debug_descr);
665	}
666
667	static inline void debug_work_deactivate(struct work_struct *work)
668	{
669	debug_object_deactivate(work, &work_debug_descr);
670	}
671
672	void __init_work(struct work_struct *work, int onstack)
673	{
674	if (onstack)
675	debug_object_init_on_stack(work, &work_debug_descr);
676	else
677	debug_object_init(work, &work_debug_descr);
678	}
679	EXPORT_SYMBOL_GPL(__init_work);
680
681	void destroy_work_on_stack(struct work_struct *work)
682	{
683	debug_object_free(work, &work_debug_descr);
684	}
685	EXPORT_SYMBOL_GPL(destroy_work_on_stack);
686
687	void destroy_delayed_work_on_stack(struct delayed_work *work)
688	{
689	destroy_timer_on_stack(&work->timer);
690	debug_object_free(&work->work, &work_debug_descr);
691	}
692	EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack);
693
694	#else
695	static inline void debug_work_activate(struct work_struct *work) { }
696	static inline void debug_work_deactivate(struct work_struct *work) { }
697	#endif
698
699	/**
700	* worker_pool_assign_id - allocate ID and assign it to @pool
701	* @pool: the pool pointer of interest
702	*
703	* Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned
704	* successfully, -errno on failure.
705	*/
706	static int worker_pool_assign_id(struct worker_pool *pool)
707	{
708	int ret;
709
710	lockdep_assert_held(&wq_pool_mutex);
711
712	ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE,
713	GFP_KERNEL);
714	if (ret >= 0) {
715	pool->id = ret;
716	return 0;
717	}
718	return ret;
719	}
720
721	static struct pool_workqueue __rcu **
722	unbound_pwq_slot(struct workqueue_struct *wq, int cpu)
723	{
724	if (cpu >= 0)
725	return per_cpu_ptr(wq->cpu_pwq, cpu);
726	else
727	return &wq->dfl_pwq;
728	}
729
730	/* @cpu < 0 for dfl_pwq */
731	static struct pool_workqueue unbound_pwq(struct workqueue_struct wq, int cpu)
732	{
733	return rcu_dereference_check(*unbound_pwq_slot(wq, cpu),
734	lockdep_is_held(&wq_pool_mutex) \|\|
735	lockdep_is_held(&wq->mutex));
736	}
737
738	/**
739	* unbound_effective_cpumask - effective cpumask of an unbound workqueue
740	* @wq: workqueue of interest
741	*
742	* @wq->unbound_attrs->cpumask contains the cpumask requested by the user which
743	* is masked with wq_unbound_cpumask to determine the effective cpumask. The
744	* default pwq is always mapped to the pool with the current effective cpumask.
745	*/
746	static struct cpumask unbound_effective_cpumask(struct workqueue_struct wq)
747	{
748	return unbound_pwq(wq, -1)->pool->attrs->__pod_cpumask;
749	}
750
751	static unsigned int work_color_to_flags(int color)
752	{
753	return color << WORK_STRUCT_COLOR_SHIFT;
754	}
755
756	static int get_work_color(unsigned long work_data)
757	{
758	return (work_data >> WORK_STRUCT_COLOR_SHIFT) &
759	((1 << WORK_STRUCT_COLOR_BITS) - 1);
760	}
761
762	static int work_next_color(int color)
763	{
764	return (color + 1) % WORK_NR_COLORS;
765	}
766
767	static unsigned long pool_offq_flags(struct worker_pool *pool)
768	{
769	return (pool->flags & POOL_BH) ? WORK_OFFQ_BH : 0;
770	}
771
772	/*
773	* While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
774	* contain the pointer to the queued pwq. Once execution starts, the flag
775	* is cleared and the high bits contain OFFQ flags and pool ID.
776	*
777	* set_work_pwq(), set_work_pool_and_clear_pending() and mark_work_canceling()
778	* can be used to set the pwq, pool or clear work->data. These functions should
779	* only be called while the work is owned - ie. while the PENDING bit is set.
780	*
781	* get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
782	* corresponding to a work. Pool is available once the work has been
783	* queued anywhere after initialization until it is sync canceled. pwq is
784	* available only while the work item is queued.
785	*/
786	static inline void set_work_data(struct work_struct *work, unsigned long data)
787	{
788	WARN_ON_ONCE(!work_pending(work));
789	atomic_long_set(&work->data, data \| work_static(work));
790	}
791
792	static void set_work_pwq(struct work_struct work, struct pool_workqueue pwq,
793	unsigned long flags)
794	{
795	set_work_data(work, (unsigned long)pwq \| WORK_STRUCT_PENDING \|
796	WORK_STRUCT_PWQ \| flags);
797	}
798
799	static void set_work_pool_and_keep_pending(struct work_struct *work,
800	int pool_id, unsigned long flags)
801	{
802	set_work_data(work, ((unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT) \|
803	WORK_STRUCT_PENDING \| flags);
804	}
805
806	static void set_work_pool_and_clear_pending(struct work_struct *work,
807	int pool_id, unsigned long flags)
808	{
809	/*
810	* The following wmb is paired with the implied mb in
811	* test_and_set_bit(PENDING) and ensures all updates to @work made
812	* here are visible to and precede any updates by the next PENDING
813	* owner.
814	*/
815	smp_wmb();
816	set_work_data(work, ((unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT) \|
817	flags);
818	/*
819	* The following mb guarantees that previous clear of a PENDING bit
820	* will not be reordered with any speculative LOADS or STORES from
821	* work->current_func, which is executed afterwards. This possible
822	* reordering can lead to a missed execution on attempt to queue
823	* the same @work. E.g. consider this case:
824	*
825	* CPU#0 CPU#1
826	* ---------------------------- --------------------------------
827	*
828	* 1 STORE event_indicated
829	* 2 queue_work_on() {
830	* 3 test_and_set_bit(PENDING)
831	* 4 } set_..._and_clear_pending() {
832	* 5 set_work_data() # clear bit
833	* 6 smp_mb()
834	* 7 work->current_func() {
835	* 8 LOAD event_indicated
836	* }
837	*
838	* Without an explicit full barrier speculative LOAD on line 8 can
839	* be executed before CPU#0 does STORE on line 1. If that happens,
840	* CPU#0 observes the PENDING bit is still set and new execution of
841	* a @work is not queued in a hope, that CPU#1 will eventually
842	* finish the queued @work. Meanwhile CPU#1 does not see
843	* event_indicated is set, because speculative LOAD was executed
844	* before actual STORE.
845	*/
846	smp_mb();
847	}
848
849	static inline struct pool_workqueue *work_struct_pwq(unsigned long data)
850	{
851	return (struct pool_workqueue *)(data & WORK_STRUCT_PWQ_MASK);
852	}
853
854	static struct pool_workqueue get_work_pwq(struct work_struct work)
855	{
856	unsigned long data = atomic_long_read(&work->data);
857
858	if (data & WORK_STRUCT_PWQ)
859	return work_struct_pwq(data);
860	else
861	return NULL;
862	}
863
864	/**
865	* get_work_pool - return the worker_pool a given work was associated with
866	* @work: the work item of interest
867	*
868	* Pools are created and destroyed under wq_pool_mutex, and allows read
869	* access under RCU read lock. As such, this function should be
870	* called under wq_pool_mutex or inside of a rcu_read_lock() region.
871	*
872	* All fields of the returned pool are accessible as long as the above
873	* mentioned locking is in effect. If the returned pool needs to be used
874	* beyond the critical section, the caller is responsible for ensuring the
875	* returned pool is and stays online.
876	*
877	* Return: The worker_pool @work was last associated with. %NULL if none.
878	*/
879	static struct worker_pool get_work_pool(struct work_struct work)
880	{
881	unsigned long data = atomic_long_read(&work->data);
882	int pool_id;
883
884	assert_rcu_or_pool_mutex();
885
886	if (data & WORK_STRUCT_PWQ)
887	return work_struct_pwq(data)->pool;
888
889	pool_id = data >> WORK_OFFQ_POOL_SHIFT;
890	if (pool_id == WORK_OFFQ_POOL_NONE)
891	return NULL;
892
893	return idr_find(&worker_pool_idr, pool_id);
894	}
895
896	static unsigned long shift_and_mask(unsigned long v, u32 shift, u32 bits)
897	{
898	return (v >> shift) & ((1U << bits) - 1);
899	}
900
901	static void work_offqd_unpack(struct work_offq_data *offqd, unsigned long data)
902	{
903	WARN_ON_ONCE(data & WORK_STRUCT_PWQ);
904
905	offqd->pool_id = shift_and_mask(data, WORK_OFFQ_POOL_SHIFT,
906	WORK_OFFQ_POOL_BITS);
907	offqd->disable = shift_and_mask(data, WORK_OFFQ_DISABLE_SHIFT,
908	WORK_OFFQ_DISABLE_BITS);
909	offqd->flags = data & WORK_OFFQ_FLAG_MASK;
910	}
911
912	static unsigned long work_offqd_pack_flags(struct work_offq_data *offqd)
913	{
914	return ((unsigned long)offqd->disable << WORK_OFFQ_DISABLE_SHIFT) \|
915	((unsigned long)offqd->flags);
916	}
917
918	/*
919	* Policy functions. These define the policies on how the global worker
920	* pools are managed. Unless noted otherwise, these functions assume that
921	* they're being called with pool->lock held.
922	*/
923
924	/*
925	* Need to wake up a worker? Called from anything but currently
926	* running workers.
927	*
928	* Note that, because unbound workers never contribute to nr_running, this
929	* function will always return %true for unbound pools as long as the
930	* worklist isn't empty.
931	*/
932	static bool need_more_worker(struct worker_pool *pool)
933	{
934	return !list_empty(&pool->worklist) && !pool->nr_running;
935	}
936
937	/* Can I start working? Called from busy but !running workers. */
938	static bool may_start_working(struct worker_pool *pool)
939	{
940	return pool->nr_idle;
941	}
942
943	/* Do I need to keep working? Called from currently running workers. */
944	static bool keep_working(struct worker_pool *pool)
945	{
946	return !list_empty(&pool->worklist) && (pool->nr_running <= 1);
947	}
948
949	/* Do we need a new worker? Called from manager. */
950	static bool need_to_create_worker(struct worker_pool *pool)
951	{
952	return need_more_worker(pool) && !may_start_working(pool);
953	}
954
955	/* Do we have too many workers and should some go away? */
956	static bool too_many_workers(struct worker_pool *pool)
957	{
958	bool managing = pool->flags & POOL_MANAGER_ACTIVE;
959	int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
960	int nr_busy = pool->nr_workers - nr_idle;
961
962	return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
963	}
964
965	/**
966	* worker_set_flags - set worker flags and adjust nr_running accordingly
967	* @worker: self
968	* @flags: flags to set
969	*
970	* Set @flags in @worker->flags and adjust nr_running accordingly.
971	*/
972	static inline void worker_set_flags(struct worker *worker, unsigned int flags)
973	{
974	struct worker_pool *pool = worker->pool;
975
976	lockdep_assert_held(&pool->lock);
977
978	/* If transitioning into NOT_RUNNING, adjust nr_running. */
979	if ((flags & WORKER_NOT_RUNNING) &&
980	!(worker->flags & WORKER_NOT_RUNNING)) {
981	pool->nr_running--;
982	}
983
984	worker->flags \|= flags;
985	}
986
987	/**
988	* worker_clr_flags - clear worker flags and adjust nr_running accordingly
989	* @worker: self
990	* @flags: flags to clear
991	*
992	* Clear @flags in @worker->flags and adjust nr_running accordingly.
993	*/
994	static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
995	{
996	struct worker_pool *pool = worker->pool;
997	unsigned int oflags = worker->flags;
998
999	lockdep_assert_held(&pool->lock);
1000
1001	worker->flags &= ~flags;
1002
1003	/*
1004	* If transitioning out of NOT_RUNNING, increment nr_running. Note
1005	* that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
1006	* of multiple flags, not a single flag.
1007	*/
1008	if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
1009	if (!(worker->flags & WORKER_NOT_RUNNING))
1010	pool->nr_running++;
1011	}
1012
1013	/* Return the first idle worker. Called with pool->lock held. */
1014	static struct worker first_idle_worker(struct worker_pool pool)
1015	{
1016	if (unlikely(list_empty(&pool->idle_list)))
1017	return NULL;
1018
1019	return list_first_entry(&pool->idle_list, struct worker, entry);
1020	}
1021
1022	/**
1023	* worker_enter_idle - enter idle state
1024	* @worker: worker which is entering idle state
1025	*
1026	* @worker is entering idle state. Update stats and idle timer if
1027	* necessary.
1028	*
1029	* LOCKING:
1030	* raw_spin_lock_irq(pool->lock).
1031	*/
1032	static void worker_enter_idle(struct worker *worker)
1033	{
1034	struct worker_pool *pool = worker->pool;
1035
1036	if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) \|\|
1037	WARN_ON_ONCE(!list_empty(&worker->entry) &&
1038	(worker->hentry.next \|\| worker->hentry.pprev)))
1039	return;
1040
1041	/* can't use worker_set_flags(), also called from create_worker() */
1042	worker->flags \|= WORKER_IDLE;
1043	pool->nr_idle++;
1044	worker->last_active = jiffies;
1045
1046	/* idle_list is LIFO */
1047	list_add(&worker->entry, &pool->idle_list);
1048
1049	if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
1050	mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
1051
1052	/* Sanity check nr_running. */
1053	WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && pool->nr_running);
1054	}
1055
1056	/**
1057	* worker_leave_idle - leave idle state
1058	* @worker: worker which is leaving idle state
1059	*
1060	* @worker is leaving idle state. Update stats.
1061	*
1062	* LOCKING:
1063	* raw_spin_lock_irq(pool->lock).
1064	*/
1065	static void worker_leave_idle(struct worker *worker)
1066	{
1067	struct worker_pool *pool = worker->pool;
1068
1069	if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
1070	return;
1071	worker_clr_flags(worker, WORKER_IDLE);
1072	pool->nr_idle--;
1073	list_del_init(&worker->entry);
1074	}
1075
1076	/**
1077	* find_worker_executing_work - find worker which is executing a work
1078	* @pool: pool of interest
1079	* @work: work to find worker for
1080	*
1081	* Find a worker which is executing @work on @pool by searching
1082	* @pool->busy_hash which is keyed by the address of @work. For a worker
1083	* to match, its current execution should match the address of @work and
1084	* its work function. This is to avoid unwanted dependency between
1085	* unrelated work executions through a work item being recycled while still
1086	* being executed.
1087	*
1088	* This is a bit tricky. A work item may be freed once its execution
1089	* starts and nothing prevents the freed area from being recycled for
1090	* another work item. If the same work item address ends up being reused
1091	* before the original execution finishes, workqueue will identify the
1092	* recycled work item as currently executing and make it wait until the
1093	* current execution finishes, introducing an unwanted dependency.
1094	*
1095	* This function checks the work item address and work function to avoid
1096	* false positives. Note that this isn't complete as one may construct a
1097	* work function which can introduce dependency onto itself through a
1098	* recycled work item. Well, if somebody wants to shoot oneself in the
1099	* foot that badly, there's only so much we can do, and if such deadlock
1100	* actually occurs, it should be easy to locate the culprit work function.
1101	*
1102	* CONTEXT:
1103	* raw_spin_lock_irq(pool->lock).
1104	*
1105	* Return:
1106	* Pointer to worker which is executing @work if found, %NULL
1107	* otherwise.
1108	*/
1109	static struct worker find_worker_executing_work(struct worker_pool pool,
1110	struct work_struct *work)
1111	{
1112	struct worker *worker;
1113
1114	hash_for_each_possible(pool->busy_hash, worker, hentry,
1115	(unsigned long)work)
1116	if (worker->current_work == work &&
1117	worker->current_func == work->func)
1118	return worker;
1119
1120	return NULL;
1121	}
1122
1123	/**
1124	* move_linked_works - move linked works to a list
1125	* @work: start of series of works to be scheduled
1126	* @head: target list to append @work to
1127	* @nextp: out parameter for nested worklist walking
1128	*
1129	* Schedule linked works starting from @work to @head. Work series to be
1130	* scheduled starts at @work and includes any consecutive work with
1131	* WORK_STRUCT_LINKED set in its predecessor. See assign_work() for details on
1132	* @nextp.
1133	*
1134	* CONTEXT:
1135	* raw_spin_lock_irq(pool->lock).
1136	*/
1137	static void move_linked_works(struct work_struct work, struct list_head head,
1138	struct work_struct **nextp)
1139	{
1140	struct work_struct *n;
1141
1142	/*
1143	* Linked worklist will always end before the end of the list,
1144	* use NULL for list head.
1145	*/
1146	list_for_each_entry_safe_from(work, n, NULL, entry) {
1147	list_move_tail(&work->entry, head);
1148	if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
1149	break;
1150	}
1151
1152	/*
1153	* If we're already inside safe list traversal and have moved
1154	* multiple works to the scheduled queue, the next position
1155	* needs to be updated.
1156	*/
1157	if (nextp)
1158	*nextp = n;
1159	}
1160
1161	/**
1162	* assign_work - assign a work item and its linked work items to a worker
1163	* @work: work to assign
1164	* @worker: worker to assign to
1165	* @nextp: out parameter for nested worklist walking
1166	*
1167	* Assign @work and its linked work items to @worker. If @work is already being
1168	* executed by another worker in the same pool, it'll be punted there.
1169	*
1170	* If @nextp is not NULL, it's updated to point to the next work of the last
1171	* scheduled work. This allows assign_work() to be nested inside
1172	* list_for_each_entry_safe().
1173	*
1174	* Returns %true if @work was successfully assigned to @worker. %false if @work
1175	* was punted to another worker already executing it.
1176	*/
1177	static bool assign_work(struct work_struct work, struct worker worker,
1178	struct work_struct **nextp)
1179	{
1180	struct worker_pool *pool = worker->pool;
1181	struct worker *collision;
1182
1183	lockdep_assert_held(&pool->lock);
1184
1185	/*
1186	* A single work shouldn't be executed concurrently by multiple workers.
1187	* __queue_work() ensures that @work doesn't jump to a different pool
1188	* while still running in the previous pool. Here, we should ensure that
1189	* @work is not executed concurrently by multiple workers from the same
1190	* pool. Check whether anyone is already processing the work. If so,
1191	* defer the work to the currently executing one.
1192	*/
1193	collision = find_worker_executing_work(pool, work);
1194	if (unlikely(collision)) {
1195	move_linked_works(work, &collision->scheduled, nextp);
1196	return false;
1197	}
1198
1199	move_linked_works(work, &worker->scheduled, nextp);
1200	return true;
1201	}
1202
1203	static struct irq_work bh_pool_irq_work(struct worker_pool pool)
1204	{
1205	int high = pool->attrs->nice == HIGHPRI_NICE_LEVEL ? 1 : 0;
1206
1207	return &per_cpu(bh_pool_irq_works, pool->cpu)[high];
1208	}
1209
1210	static void kick_bh_pool(struct worker_pool *pool)
1211	{
1212	#ifdef CONFIG_SMP
1213	/* see drain_dead_softirq_workfn() for BH_DRAINING */
1214	if (unlikely(pool->cpu != smp_processor_id() &&
1215	!(pool->flags & POOL_BH_DRAINING))) {
1216	irq_work_queue_on(bh_pool_irq_work(pool), pool->cpu);
1217	return;
1218	}
1219	#endif
1220	if (pool->attrs->nice == HIGHPRI_NICE_LEVEL)
1221	raise_softirq_irqoff(HI_SOFTIRQ);
1222	else
1223	raise_softirq_irqoff(TASKLET_SOFTIRQ);
1224	}
1225
1226	/**
1227	* kick_pool - wake up an idle worker if necessary
1228	* @pool: pool to kick
1229	*
1230	* @pool may have pending work items. Wake up worker if necessary. Returns
1231	* whether a worker was woken up.
1232	*/
1233	static bool kick_pool(struct worker_pool *pool)
1234	{
1235	struct worker *worker = first_idle_worker(pool);
1236	struct task_struct *p;
1237
1238	lockdep_assert_held(&pool->lock);
1239
1240	if (!need_more_worker(pool) \|\| !worker)
1241	return false;
1242
1243	if (pool->flags & POOL_BH) {
1244	kick_bh_pool(pool);
1245	return true;
1246	}
1247
1248	p = worker->task;
1249
1250	#ifdef CONFIG_SMP
1251	/*
1252	* Idle @worker is about to execute @work and waking up provides an
1253	* opportunity to migrate @worker at a lower cost by setting the task's
1254	* wake_cpu field. Let's see if we want to move @worker to improve
1255	* execution locality.
1256	*
1257	* We're waking the worker that went idle the latest and there's some
1258	* chance that @worker is marked idle but hasn't gone off CPU yet. If
1259	* so, setting the wake_cpu won't do anything. As this is a best-effort
1260	* optimization and the race window is narrow, let's leave as-is for
1261	* now. If this becomes pronounced, we can skip over workers which are
1262	* still on cpu when picking an idle worker.
1263	*
1264	* If @pool has non-strict affinity, @worker might have ended up outside
1265	* its affinity scope. Repatriate.
1266	*/
1267	if (!pool->attrs->affn_strict &&
1268	!cpumask_test_cpu(p->wake_cpu, pool->attrs->__pod_cpumask)) {
1269	struct work_struct *work = list_first_entry(&pool->worklist,
1270	struct work_struct, entry);
1271	int wake_cpu = cpumask_any_and_distribute(pool->attrs->__pod_cpumask,
1272	cpu_online_mask);
1273	if (wake_cpu < nr_cpu_ids) {
1274	p->wake_cpu = wake_cpu;
1275	get_work_pwq(work)->stats[PWQ_STAT_REPATRIATED]++;
1276	}
1277	}
1278	#endif
1279	wake_up_process(p);
1280	return true;
1281	}
1282
1283	#ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT
1284
1285	/*
1286	* Concurrency-managed per-cpu work items that hog CPU for longer than
1287	* wq_cpu_intensive_thresh_us trigger the automatic CPU_INTENSIVE mechanism,
1288	* which prevents them from stalling other concurrency-managed work items. If a
1289	* work function keeps triggering this mechanism, it's likely that the work item
1290	* should be using an unbound workqueue instead.
1291	*
1292	* wq_cpu_intensive_report() tracks work functions which trigger such conditions
1293	* and report them so that they can be examined and converted to use unbound
1294	* workqueues as appropriate. To avoid flooding the console, each violating work
1295	* function is tracked and reported with exponential backoff.
1296	*/
1297	#define WCI_MAX_ENTS 128
1298
1299	struct wci_ent {
1300	work_func_t func;
1301	atomic64_t cnt;
1302	struct hlist_node hash_node;
1303	};
1304
1305	static struct wci_ent wci_ents[WCI_MAX_ENTS];
1306	static int wci_nr_ents;
1307	static DEFINE_RAW_SPINLOCK(wci_lock);
1308	static DEFINE_HASHTABLE(wci_hash, ilog2(WCI_MAX_ENTS));
1309
1310	static struct wci_ent *wci_find_ent(work_func_t func)
1311	{
1312	struct wci_ent *ent;
1313
1314	hash_for_each_possible_rcu(wci_hash, ent, hash_node,
1315	(unsigned long)func) {
1316	if (ent->func == func)
1317	return ent;
1318	}
1319	return NULL;
1320	}
1321
1322	static void wq_cpu_intensive_report(work_func_t func)
1323	{
1324	struct wci_ent *ent;
1325
1326	restart:
1327	ent = wci_find_ent(func);
1328	if (ent) {
1329	u64 cnt;
1330
1331	/*
1332	* Start reporting from the warning_thresh and back off
1333	* exponentially.
1334	*/
1335	cnt = atomic64_inc_return_relaxed(&ent->cnt);
1336	if (wq_cpu_intensive_warning_thresh &&
1337	cnt >= wq_cpu_intensive_warning_thresh &&
1338	is_power_of_2(cnt + 1 - wq_cpu_intensive_warning_thresh))
1339	printk_deferred(KERN_WARNING "workqueue: %ps hogged CPU for >%luus %llu times, consider switching to WQ_UNBOUND\n",
1340	ent->func, wq_cpu_intensive_thresh_us,
1341	atomic64_read(&ent->cnt));
1342	return;
1343	}
1344
1345	/*
1346	* @func is a new violation. Allocate a new entry for it. If wcn_ents[]
1347	* is exhausted, something went really wrong and we probably made enough
1348	* noise already.
1349	*/
1350	if (wci_nr_ents >= WCI_MAX_ENTS)
1351	return;
1352
1353	raw_spin_lock(&wci_lock);
1354
1355	if (wci_nr_ents >= WCI_MAX_ENTS) {
1356	raw_spin_unlock(&wci_lock);
1357	return;
1358	}
1359
1360	if (wci_find_ent(func)) {
1361	raw_spin_unlock(&wci_lock);
1362	goto restart;
1363	}
1364
1365	ent = &wci_ents[wci_nr_ents++];
1366	ent->func = func;
1367	atomic64_set(&ent->cnt, 0);
1368	hash_add_rcu(wci_hash, &ent->hash_node, (unsigned long)func);
1369
1370	raw_spin_unlock(&wci_lock);
1371
1372	goto restart;
1373	}
1374
1375	#else /* CONFIG_WQ_CPU_INTENSIVE_REPORT */
1376	static void wq_cpu_intensive_report(work_func_t func) {}
1377	#endif /* CONFIG_WQ_CPU_INTENSIVE_REPORT */
1378
1379	/**
1380	* wq_worker_running - a worker is running again
1381	* @task: task waking up
1382	*
1383	* This function is called when a worker returns from schedule()
1384	*/
1385	void wq_worker_running(struct task_struct *task)
1386	{
1387	struct worker *worker = kthread_data(task);
1388
1389	if (!READ_ONCE(worker->sleeping))
1390	return;
1391
1392	/*
1393	* If preempted by unbind_workers() between the WORKER_NOT_RUNNING check
1394	* and the nr_running increment below, we may ruin the nr_running reset
1395	* and leave with an unexpected pool->nr_running == 1 on the newly unbound
1396	* pool. Protect against such race.
1397	*/
1398	preempt_disable();
1399	if (!(worker->flags & WORKER_NOT_RUNNING))
1400	worker->pool->nr_running++;
1401	preempt_enable();
1402
1403	/*
1404	* CPU intensive auto-detection cares about how long a work item hogged
1405	* CPU without sleeping. Reset the starting timestamp on wakeup.
1406	*/
1407	worker->current_at = worker->task->se.sum_exec_runtime;
1408
1409	WRITE_ONCE(worker->sleeping, 0);
1410	}
1411
1412	/**
1413	* wq_worker_sleeping - a worker is going to sleep
1414	* @task: task going to sleep
1415	*
1416	* This function is called from schedule() when a busy worker is
1417	* going to sleep.
1418	*/
1419	void wq_worker_sleeping(struct task_struct *task)
1420	{
1421	struct worker *worker = kthread_data(task);
1422	struct worker_pool *pool;
1423
1424	/*
1425	* Rescuers, which may not have all the fields set up like normal
1426	* workers, also reach here, let's not access anything before
1427	* checking NOT_RUNNING.
1428	*/
1429	if (worker->flags & WORKER_NOT_RUNNING)
1430	return;
1431
1432	pool = worker->pool;
1433
1434	/* Return if preempted before wq_worker_running() was reached */
1435	if (READ_ONCE(worker->sleeping))
1436	return;
1437
1438	WRITE_ONCE(worker->sleeping, 1);
1439	raw_spin_lock_irq(&pool->lock);
1440
1441	/*
1442	* Recheck in case unbind_workers() preempted us. We don't
1443	* want to decrement nr_running after the worker is unbound
1444	* and nr_running has been reset.
1445	*/
1446	if (worker->flags & WORKER_NOT_RUNNING) {
1447	raw_spin_unlock_irq(&pool->lock);
1448	return;
1449	}
1450
1451	pool->nr_running--;
1452	if (kick_pool(pool))
1453	worker->current_pwq->stats[PWQ_STAT_CM_WAKEUP]++;
1454
1455	raw_spin_unlock_irq(&pool->lock);
1456	}
1457
1458	/**
1459	* wq_worker_tick - a scheduler tick occurred while a kworker is running
1460	* @task: task currently running
1461	*
1462	* Called from sched_tick(). We're in the IRQ context and the current
1463	* worker's fields which follow the 'K' locking rule can be accessed safely.
1464	*/
1465	void wq_worker_tick(struct task_struct *task)
1466	{
1467	struct worker *worker = kthread_data(task);
1468	struct pool_workqueue *pwq = worker->current_pwq;
1469	struct worker_pool *pool = worker->pool;
1470
1471	if (!pwq)
1472	return;
1473
1474	pwq->stats[PWQ_STAT_CPU_TIME] += TICK_USEC;
1475
1476	if (!wq_cpu_intensive_thresh_us)
1477	return;
1478
1479	/*
1480	* If the current worker is concurrency managed and hogged the CPU for
1481	* longer than wq_cpu_intensive_thresh_us, it's automatically marked
1482	* CPU_INTENSIVE to avoid stalling other concurrency-managed work items.
1483	*
1484	* Set @worker->sleeping means that @worker is in the process of
1485	* switching out voluntarily and won't be contributing to
1486	* @pool->nr_running until it wakes up. As wq_worker_sleeping() also
1487	* decrements ->nr_running, setting CPU_INTENSIVE here can lead to
1488	* double decrements. The task is releasing the CPU anyway. Let's skip.
1489	* We probably want to make this prettier in the future.
1490	*/
1491	if ((worker->flags & WORKER_NOT_RUNNING) \|\| READ_ONCE(worker->sleeping) \|\|
1492	worker->task->se.sum_exec_runtime - worker->current_at <
1493	wq_cpu_intensive_thresh_us * NSEC_PER_USEC)
1494	return;
1495
1496	raw_spin_lock(&pool->lock);
1497
1498	worker_set_flags(worker, WORKER_CPU_INTENSIVE);
1499	wq_cpu_intensive_report(worker->current_func);
1500	pwq->stats[PWQ_STAT_CPU_INTENSIVE]++;
1501
1502	if (kick_pool(pool))
1503	pwq->stats[PWQ_STAT_CM_WAKEUP]++;
1504
1505	raw_spin_unlock(&pool->lock);
1506	}
1507
1508	/**
1509	* wq_worker_last_func - retrieve worker's last work function
1510	* @task: Task to retrieve last work function of.
1511	*
1512	* Determine the last function a worker executed. This is called from
1513	* the scheduler to get a worker's last known identity.
1514	*
1515	* CONTEXT:
1516	* raw_spin_lock_irq(rq->lock)
1517	*
1518	* This function is called during schedule() when a kworker is going
1519	* to sleep. It's used by psi to identify aggregation workers during
1520	* dequeuing, to allow periodic aggregation to shut-off when that
1521	* worker is the last task in the system or cgroup to go to sleep.
1522	*
1523	* As this function doesn't involve any workqueue-related locking, it
1524	* only returns stable values when called from inside the scheduler's
1525	* queuing and dequeuing paths, when @task, which must be a kworker,
1526	* is guaranteed to not be processing any works.
1527	*
1528	* Return:
1529	* The last work function %current executed as a worker, NULL if it
1530	* hasn't executed any work yet.
1531	*/
1532	work_func_t wq_worker_last_func(struct task_struct *task)
1533	{
1534	struct worker *worker = kthread_data(task);
1535
1536	return worker->last_func;
1537	}
1538
1539	/**
1540	* wq_node_nr_active - Determine wq_node_nr_active to use
1541	* @wq: workqueue of interest
1542	* @node: NUMA node, can be %NUMA_NO_NODE
1543	*
1544	* Determine wq_node_nr_active to use for @wq on @node. Returns:
1545	*
1546	* - %NULL for per-cpu workqueues as they don't need to use shared nr_active.
1547	*
1548	* - node_nr_active[nr_node_ids] if @node is %NUMA_NO_NODE.
1549	*
1550	* - Otherwise, node_nr_active[@node].
1551	*/
1552	static struct wq_node_nr_active wq_node_nr_active(struct workqueue_struct wq,
1553	int node)
1554	{
1555	if (!(wq->flags & WQ_UNBOUND))
1556	return NULL;
1557
1558	if (node == NUMA_NO_NODE)
1559	node = nr_node_ids;
1560
1561	return wq->node_nr_active[node];
1562	}
1563
1564	/**
1565	* wq_update_node_max_active - Update per-node max_actives to use
1566	* @wq: workqueue to update
1567	* @off_cpu: CPU that's going down, -1 if a CPU is not going down
1568	*
1569	* Update @wq->node_nr_active[]->max. @wq must be unbound. max_active is
1570	* distributed among nodes according to the proportions of numbers of online
1571	* cpus. The result is always between @wq->min_active and max_active.
1572	*/
1573	static void wq_update_node_max_active(struct workqueue_struct *wq, int off_cpu)
1574	{
1575	struct cpumask *effective = unbound_effective_cpumask(wq);
1576	int min_active = READ_ONCE(wq->min_active);
1577	int max_active = READ_ONCE(wq->max_active);
1578	int total_cpus, node;
1579
1580	lockdep_assert_held(&wq->mutex);
1581
1582	if (!wq_topo_initialized)
1583	return;
1584
1585	if (off_cpu >= 0 && !cpumask_test_cpu(off_cpu, effective))
1586	off_cpu = -1;
1587
1588	total_cpus = cpumask_weight_and(effective, cpu_online_mask);
1589	if (off_cpu >= 0)
1590	total_cpus--;
1591
1592	/* If all CPUs of the wq get offline, use the default values */
1593	if (unlikely(!total_cpus)) {
1594	for_each_node(node)
1595	wq_node_nr_active(wq, node)->max = min_active;
1596
1597	wq_node_nr_active(wq, NUMA_NO_NODE)->max = max_active;
1598	return;
1599	}
1600
1601	for_each_node(node) {
1602	int node_cpus;
1603
1604	node_cpus = cpumask_weight_and(effective, cpumask_of_node(node));
1605	if (off_cpu >= 0 && cpu_to_node(off_cpu) == node)
1606	node_cpus--;
1607
1608	wq_node_nr_active(wq, node)->max =
1609	clamp(DIV_ROUND_UP(max_active * node_cpus, total_cpus),
1610	min_active, max_active);
1611	}
1612
1613	wq_node_nr_active(wq, NUMA_NO_NODE)->max = max_active;
1614	}
1615
1616	/**
1617	* get_pwq - get an extra reference on the specified pool_workqueue
1618	* @pwq: pool_workqueue to get
1619	*
1620	* Obtain an extra reference on @pwq. The caller should guarantee that
1621	* @pwq has positive refcnt and be holding the matching pool->lock.
1622	*/
1623	static void get_pwq(struct pool_workqueue *pwq)
1624	{
1625	lockdep_assert_held(&pwq->pool->lock);
1626	WARN_ON_ONCE(pwq->refcnt <= 0);
1627	pwq->refcnt++;
1628	}
1629
1630	/**
1631	* put_pwq - put a pool_workqueue reference
1632	* @pwq: pool_workqueue to put
1633	*
1634	* Drop a reference of @pwq. If its refcnt reaches zero, schedule its
1635	* destruction. The caller should be holding the matching pool->lock.
1636	*/
1637	static void put_pwq(struct pool_workqueue *pwq)
1638	{
1639	lockdep_assert_held(&pwq->pool->lock);
1640	if (likely(--pwq->refcnt))
1641	return;
1642	/*
1643	* @pwq can't be released under pool->lock, bounce to a dedicated
1644	* kthread_worker to avoid A-A deadlocks.
1645	*/
1646	kthread_queue_work(pwq_release_worker, &pwq->release_work);
1647	}
1648
1649	/**
1650	* put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
1651	* @pwq: pool_workqueue to put (can be %NULL)
1652	*
1653	* put_pwq() with locking. This function also allows %NULL @pwq.
1654	*/
1655	static void put_pwq_unlocked(struct pool_workqueue *pwq)
1656	{
1657	if (pwq) {
1658	/*
1659	* As both pwqs and pools are RCU protected, the
1660	* following lock operations are safe.
1661	*/
1662	raw_spin_lock_irq(&pwq->pool->lock);
1663	put_pwq(pwq);
1664	raw_spin_unlock_irq(&pwq->pool->lock);
1665	}
1666	}
1667
1668	static bool pwq_is_empty(struct pool_workqueue *pwq)
1669	{
1670	return !pwq->nr_active && list_empty(&pwq->inactive_works);
1671	}
1672
1673	static void __pwq_activate_work(struct pool_workqueue *pwq,
1674	struct work_struct *work)
1675	{
1676	unsigned long *wdb = work_data_bits(work);
1677
1678	WARN_ON_ONCE(!(*wdb & WORK_STRUCT_INACTIVE));
1679	trace_workqueue_activate_work(work);
1680	if (list_empty(&pwq->pool->worklist))
1681	pwq->pool->watchdog_ts = jiffies;
1682	move_linked_works(work, &pwq->pool->worklist, NULL);
1683	__clear_bit(WORK_STRUCT_INACTIVE_BIT, wdb);
1684	}
1685
1686	static bool tryinc_node_nr_active(struct wq_node_nr_active *nna)
1687	{
1688	int max = READ_ONCE(nna->max);
1689
1690	while (true) {
1691	int old, tmp;
1692
1693	old = atomic_read(&nna->nr);
1694	if (old >= max)
1695	return false;
1696	tmp = atomic_cmpxchg_relaxed(&nna->nr, old, old + 1);
1697	if (tmp == old)
1698	return true;
1699	}
1700	}
1701
1702	/**
1703	* pwq_tryinc_nr_active - Try to increment nr_active for a pwq
1704	* @pwq: pool_workqueue of interest
1705	* @fill: max_active may have increased, try to increase concurrency level
1706	*
1707	* Try to increment nr_active for @pwq. Returns %true if an nr_active count is
1708	* successfully obtained. %false otherwise.
1709	*/
1710	static bool pwq_tryinc_nr_active(struct pool_workqueue *pwq, bool fill)
1711	{
1712	struct workqueue_struct *wq = pwq->wq;
1713	struct worker_pool *pool = pwq->pool;
1714	struct wq_node_nr_active *nna = wq_node_nr_active(wq, pool->node);
1715	bool obtained = false;
1716
1717	lockdep_assert_held(&pool->lock);
1718
1719	if (!nna) {
1720	/* BH or per-cpu workqueue, pwq->nr_active is sufficient */
1721	obtained = pwq->nr_active < READ_ONCE(wq->max_active);
1722	goto out;
1723	}
1724
1725	if (unlikely(pwq->plugged))
1726	return false;
1727
1728	/*
1729	* Unbound workqueue uses per-node shared nr_active $nna. If @pwq is
1730	* already waiting on $nna, pwq_dec_nr_active() will maintain the
1731	* concurrency level. Don't jump the line.
1732	*
1733	* We need to ignore the pending test after max_active has increased as
1734	* pwq_dec_nr_active() can only maintain the concurrency level but not
1735	* increase it. This is indicated by @fill.
1736	*/
1737	if (!list_empty(&pwq->pending_node) && likely(!fill))
1738	goto out;
1739
1740	obtained = tryinc_node_nr_active(nna);
1741	if (obtained)
1742	goto out;
1743
1744	/*
1745	* Lockless acquisition failed. Lock, add ourself to $nna->pending_pwqs
1746	* and try again. The smp_mb() is paired with the implied memory barrier
1747	* of atomic_dec_return() in pwq_dec_nr_active() to ensure that either
1748	* we see the decremented $nna->nr or they see non-empty
1749	* $nna->pending_pwqs.
1750	*/
1751	raw_spin_lock(&nna->lock);
1752
1753	if (list_empty(&pwq->pending_node))
1754	list_add_tail(&pwq->pending_node, &nna->pending_pwqs);
1755	else if (likely(!fill))
1756	goto out_unlock;
1757
1758	smp_mb();
1759
1760	obtained = tryinc_node_nr_active(nna);
1761
1762	/*
1763	* If @fill, @pwq might have already been pending. Being spuriously
1764	* pending in cold paths doesn't affect anything. Let's leave it be.
1765	*/
1766	if (obtained && likely(!fill))
1767	list_del_init(&pwq->pending_node);
1768
1769	out_unlock:
1770	raw_spin_unlock(&nna->lock);
1771	out:
1772	if (obtained)
1773	pwq->nr_active++;
1774	return obtained;
1775	}
1776
1777	/**
1778	* pwq_activate_first_inactive - Activate the first inactive work item on a pwq
1779	* @pwq: pool_workqueue of interest
1780	* @fill: max_active may have increased, try to increase concurrency level
1781	*
1782	* Activate the first inactive work item of @pwq if available and allowed by
1783	* max_active limit.
1784	*
1785	* Returns %true if an inactive work item has been activated. %false if no
1786	* inactive work item is found or max_active limit is reached.
1787	*/
1788	static bool pwq_activate_first_inactive(struct pool_workqueue *pwq, bool fill)
1789	{
1790	struct work_struct *work =
1791	list_first_entry_or_null(&pwq->inactive_works,
1792	struct work_struct, entry);
1793
1794	if (work && pwq_tryinc_nr_active(pwq, fill)) {
1795	__pwq_activate_work(pwq, work);
1796	return true;
1797	} else {
1798	return false;
1799	}
1800	}
1801
1802	/**
1803	* unplug_oldest_pwq - unplug the oldest pool_workqueue
1804	* @wq: workqueue_struct where its oldest pwq is to be unplugged
1805	*
1806	* This function should only be called for ordered workqueues where only the
1807	* oldest pwq is unplugged, the others are plugged to suspend execution to
1808	* ensure proper work item ordering::
1809	*
1810	* dfl_pwq --------------+ [P] - plugged
1811	* \|
1812	* v
1813	* pwqs -> A -> B [P] -> C [P] (newest)
1814	* \| \| \|
1815	* 1 3 5
1816	* \| \| \|
1817	* 2 4 6
1818	*
1819	* When the oldest pwq is drained and removed, this function should be called
1820	* to unplug the next oldest one to start its work item execution. Note that
1821	* pwq's are linked into wq->pwqs with the oldest first, so the first one in
1822	* the list is the oldest.
1823	*/
1824	static void unplug_oldest_pwq(struct workqueue_struct *wq)
1825	{
1826	struct pool_workqueue *pwq;
1827
1828	lockdep_assert_held(&wq->mutex);
1829
1830	/* Caller should make sure that pwqs isn't empty before calling */
1831	pwq = list_first_entry_or_null(&wq->pwqs, struct pool_workqueue,
1832	pwqs_node);
1833	raw_spin_lock_irq(&pwq->pool->lock);
1834	if (pwq->plugged) {
1835	pwq->plugged = false;
1836	if (pwq_activate_first_inactive(pwq, true))
1837	kick_pool(pwq->pool);
1838	}
1839	raw_spin_unlock_irq(&pwq->pool->lock);
1840	}
1841
1842	/**
1843	* node_activate_pending_pwq - Activate a pending pwq on a wq_node_nr_active
1844	* @nna: wq_node_nr_active to activate a pending pwq for
1845	* @caller_pool: worker_pool the caller is locking
1846	*
1847	* Activate a pwq in @nna->pending_pwqs. Called with @caller_pool locked.
1848	* @caller_pool may be unlocked and relocked to lock other worker_pools.
1849	*/
1850	static void node_activate_pending_pwq(struct wq_node_nr_active *nna,
1851	struct worker_pool *caller_pool)
1852	{
1853	struct worker_pool *locked_pool = caller_pool;
1854	struct pool_workqueue *pwq;
1855	struct work_struct *work;
1856
1857	lockdep_assert_held(&caller_pool->lock);
1858
1859	raw_spin_lock(&nna->lock);
1860	retry:
1861	pwq = list_first_entry_or_null(&nna->pending_pwqs,
1862	struct pool_workqueue, pending_node);
1863	if (!pwq)
1864	goto out_unlock;
1865
1866	/*
1867	* If @pwq is for a different pool than @locked_pool, we need to lock
1868	* @pwq->pool->lock. Let's trylock first. If unsuccessful, do the unlock
1869	* / lock dance. For that, we also need to release @nna->lock as it's
1870	* nested inside pool locks.
1871	*/
1872	if (pwq->pool != locked_pool) {
1873	raw_spin_unlock(&locked_pool->lock);
1874	locked_pool = pwq->pool;
1875	if (!raw_spin_trylock(&locked_pool->lock)) {
1876	raw_spin_unlock(&nna->lock);
1877	raw_spin_lock(&locked_pool->lock);
1878	raw_spin_lock(&nna->lock);
1879	goto retry;
1880	}
1881	}
1882
1883	/*
1884	* $pwq may not have any inactive work items due to e.g. cancellations.
1885	* Drop it from pending_pwqs and see if there's another one.
1886	*/
1887	work = list_first_entry_or_null(&pwq->inactive_works,
1888	struct work_struct, entry);
1889	if (!work) {
1890	list_del_init(&pwq->pending_node);
1891	goto retry;
1892	}
1893
1894	/*
1895	* Acquire an nr_active count and activate the inactive work item. If
1896	* $pwq still has inactive work items, rotate it to the end of the
1897	* pending_pwqs so that we round-robin through them. This means that
1898	* inactive work items are not activated in queueing order which is fine
1899	* given that there has never been any ordering across different pwqs.
1900	*/
1901	if (likely(tryinc_node_nr_active(nna))) {
1902	pwq->nr_active++;
1903	__pwq_activate_work(pwq, work);
1904
1905	if (list_empty(&pwq->inactive_works))
1906	list_del_init(&pwq->pending_node);
1907	else
1908	list_move_tail(&pwq->pending_node, &nna->pending_pwqs);
1909
1910	/* if activating a foreign pool, make sure it's running */
1911	if (pwq->pool != caller_pool)
1912	kick_pool(pwq->pool);
1913	}
1914
1915	out_unlock:
1916	raw_spin_unlock(&nna->lock);
1917	if (locked_pool != caller_pool) {
1918	raw_spin_unlock(&locked_pool->lock);
1919	raw_spin_lock(&caller_pool->lock);
1920	}
1921	}
1922
1923	/**
1924	* pwq_dec_nr_active - Retire an active count
1925	* @pwq: pool_workqueue of interest
1926	*
1927	* Decrement @pwq's nr_active and try to activate the first inactive work item.
1928	* For unbound workqueues, this function may temporarily drop @pwq->pool->lock.
1929	*/
1930	static void pwq_dec_nr_active(struct pool_workqueue *pwq)
1931	{
1932	struct worker_pool *pool = pwq->pool;
1933	struct wq_node_nr_active *nna = wq_node_nr_active(pwq->wq, pool->node);
1934
1935	lockdep_assert_held(&pool->lock);
1936
1937	/*
1938	* @pwq->nr_active should be decremented for both percpu and unbound
1939	* workqueues.
1940	*/
1941	pwq->nr_active--;
1942
1943	/*
1944	* For a percpu workqueue, it's simple. Just need to kick the first
1945	* inactive work item on @pwq itself.
1946	*/
1947	if (!nna) {
1948	pwq_activate_first_inactive(pwq, false);
1949	return;
1950	}
1951
1952	/*
1953	* If @pwq is for an unbound workqueue, it's more complicated because
1954	* multiple pwqs and pools may be sharing the nr_active count. When a
1955	* pwq needs to wait for an nr_active count, it puts itself on
1956	* $nna->pending_pwqs. The following atomic_dec_return()'s implied
1957	* memory barrier is paired with smp_mb() in pwq_tryinc_nr_active() to
1958	* guarantee that either we see non-empty pending_pwqs or they see
1959	* decremented $nna->nr.
1960	*
1961	* $nna->max may change as CPUs come online/offline and @pwq->wq's
1962	* max_active gets updated. However, it is guaranteed to be equal to or
1963	* larger than @pwq->wq->min_active which is above zero unless freezing.
1964	* This maintains the forward progress guarantee.
1965	*/
1966	if (atomic_dec_return(&nna->nr) >= READ_ONCE(nna->max))
1967	return;
1968
1969	if (!list_empty(&nna->pending_pwqs))
1970	node_activate_pending_pwq(nna, pool);
1971	}
1972
1973	/**
1974	* pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
1975	* @pwq: pwq of interest
1976	* @work_data: work_data of work which left the queue
1977	*
1978	* A work either has completed or is removed from pending queue,
1979	* decrement nr_in_flight of its pwq and handle workqueue flushing.
1980	*
1981	* NOTE:
1982	* For unbound workqueues, this function may temporarily drop @pwq->pool->lock
1983	* and thus should be called after all other state updates for the in-flight
1984	* work item is complete.
1985	*
1986	* CONTEXT:
1987	* raw_spin_lock_irq(pool->lock).
1988	*/
1989	static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, unsigned long work_data)
1990	{
1991	int color = get_work_color(work_data);
1992
1993	if (!(work_data & WORK_STRUCT_INACTIVE))
1994	pwq_dec_nr_active(pwq);
1995
1996	pwq->nr_in_flight[color]--;
1997
1998	/* is flush in progress and are we at the flushing tip? */
1999	if (likely(pwq->flush_color != color))
2000	goto out_put;
2001
2002	/* are there still in-flight works? */
2003	if (pwq->nr_in_flight[color])
2004	goto out_put;
2005
2006	/* this pwq is done, clear flush_color */
2007	pwq->flush_color = -1;
2008
2009	/*
2010	* If this was the last pwq, wake up the first flusher. It
2011	* will handle the rest.
2012	*/
2013	if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush))
2014	complete(&pwq->wq->first_flusher->done);
2015	out_put:
2016	put_pwq(pwq);
2017	}
2018
2019	/**
2020	* try_to_grab_pending - steal work item from worklist and disable irq
2021	* @work: work item to steal
2022	* @cflags: %WORK_CANCEL_ flags
2023	* @irq_flags: place to store irq state
2024	*
2025	* Try to grab PENDING bit of @work. This function can handle @work in any
2026	* stable state - idle, on timer or on worklist.
2027	*
2028	* Return:
2029	*
2030	* ======== ================================================================
2031	* 1 if @work was pending and we successfully stole PENDING
2032	* 0 if @work was idle and we claimed PENDING
2033	* -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
2034	* ======== ================================================================
2035	*
2036	* Note:
2037	* On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
2038	* interrupted while holding PENDING and @work off queue, irq must be
2039	* disabled on entry. This, combined with delayed_work->timer being
2040	* irqsafe, ensures that we return -EAGAIN for finite short period of time.
2041	*
2042	* On successful return, >= 0, irq is disabled and the caller is
2043	* responsible for releasing it using local_irq_restore(*@irq_flags).
2044	*
2045	* This function is safe to call from any context including IRQ handler.
2046	*/
2047	static int try_to_grab_pending(struct work_struct *work, u32 cflags,
2048	unsigned long *irq_flags)
2049	{
2050	struct worker_pool *pool;
2051	struct pool_workqueue *pwq;
2052
2053	local_irq_save(*irq_flags);
2054
2055	/* try to steal the timer if it exists */
2056	if (cflags & WORK_CANCEL_DELAYED) {
2057	struct delayed_work *dwork = to_delayed_work(work);
2058
2059	/*
2060	* dwork->timer is irqsafe. If timer_delete() fails, it's
2061	* guaranteed that the timer is not queued anywhere and not
2062	* running on the local CPU.
2063	*/
2064	if (likely(timer_delete(&dwork->timer)))
2065	return 1;
2066	}
2067
2068	/* try to claim PENDING the normal way */
2069	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
2070	return 0;
2071
2072	rcu_read_lock();
2073	/*
2074	* The queueing is in progress, or it is already queued. Try to
2075	* steal it from ->worklist without clearing WORK_STRUCT_PENDING.
2076	*/
2077	pool = get_work_pool(work);
2078	if (!pool)
2079	goto fail;
2080
2081	raw_spin_lock(&pool->lock);
2082	/*
2083	* work->data is guaranteed to point to pwq only while the work
2084	* item is queued on pwq->wq, and both updating work->data to point
2085	* to pwq on queueing and to pool on dequeueing are done under
2086	* pwq->pool->lock. This in turn guarantees that, if work->data
2087	* points to pwq which is associated with a locked pool, the work
2088	* item is currently queued on that pool.
2089	*/
2090	pwq = get_work_pwq(work);
2091	if (pwq && pwq->pool == pool) {
2092	unsigned long work_data = *work_data_bits(work);
2093
2094	debug_work_deactivate(work);
2095
2096	/*
2097	* A cancelable inactive work item must be in the
2098	* pwq->inactive_works since a queued barrier can't be
2099	* canceled (see the comments in insert_wq_barrier()).
2100	*
2101	* An inactive work item cannot be deleted directly because
2102	* it might have linked barrier work items which, if left
2103	* on the inactive_works list, will confuse pwq->nr_active
2104	* management later on and cause stall. Move the linked
2105	* barrier work items to the worklist when deleting the grabbed
2106	* item. Also keep WORK_STRUCT_INACTIVE in work_data, so that
2107	* it doesn't participate in nr_active management in later
2108	* pwq_dec_nr_in_flight().
2109	*/
2110	if (work_data & WORK_STRUCT_INACTIVE)
2111	move_linked_works(work, &pwq->pool->worklist, NULL);
2112
2113	list_del_init(&work->entry);
2114
2115	/*
2116	* work->data points to pwq iff queued. Let's point to pool. As
2117	* this destroys work->data needed by the next step, stash it.
2118	*/
2119	set_work_pool_and_keep_pending(work, pool->id,
2120	pool_offq_flags(pool));
2121
2122	/* must be the last step, see the function comment */
2123	pwq_dec_nr_in_flight(pwq, work_data);
2124
2125	raw_spin_unlock(&pool->lock);
2126	rcu_read_unlock();
2127	return 1;
2128	}
2129	raw_spin_unlock(&pool->lock);
2130	fail:
2131	rcu_read_unlock();
2132	local_irq_restore(*irq_flags);
2133	return -EAGAIN;
2134	}
2135
2136	/**
2137	* work_grab_pending - steal work item from worklist and disable irq
2138	* @work: work item to steal
2139	* @cflags: %WORK_CANCEL_ flags
2140	* @irq_flags: place to store IRQ state
2141	*
2142	* Grab PENDING bit of @work. @work can be in any stable state - idle, on timer
2143	* or on worklist.
2144	*
2145	* Can be called from any context. IRQ is disabled on return with IRQ state
2146	* stored in *@irq_flags. The caller is responsible for re-enabling it using
2147	* local_irq_restore().
2148	*
2149	* Returns %true if @work was pending. %false if idle.
2150	*/
2151	static bool work_grab_pending(struct work_struct *work, u32 cflags,
2152	unsigned long *irq_flags)
2153	{
2154	int ret;
2155
2156	while (true) {
2157	ret = try_to_grab_pending(work, cflags, irq_flags);
2158	if (ret >= 0)
2159	return ret;
2160	cpu_relax();
2161	}
2162	}
2163
2164	/**
2165	* insert_work - insert a work into a pool
2166	* @pwq: pwq @work belongs to
2167	* @work: work to insert
2168	* @head: insertion point
2169	* @extra_flags: extra WORK_STRUCT_* flags to set
2170	*
2171	* Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
2172	* work_struct flags.
2173	*
2174	* CONTEXT:
2175	* raw_spin_lock_irq(pool->lock).
2176	*/
2177	static void insert_work(struct pool_workqueue pwq, struct work_struct work,
2178	struct list_head *head, unsigned int extra_flags)
2179	{
2180	debug_work_activate(work);
2181
2182	/* record the work call stack in order to print it in KASAN reports */
2183	kasan_record_aux_stack(work);
2184
2185	/* we own @work, set data and link */
2186	set_work_pwq(work, pwq, extra_flags);
2187	list_add_tail(&work->entry, head);
2188	get_pwq(pwq);
2189	}
2190
2191	/*
2192	* Test whether @work is being queued from another work executing on the
2193	* same workqueue.
2194	*/
2195	static bool is_chained_work(struct workqueue_struct *wq)
2196	{
2197	struct worker *worker;
2198
2199	worker = current_wq_worker();
2200	/*
2201	* Return %true iff I'm a worker executing a work item on @wq. If
2202	* I'm @worker, it's safe to dereference it without locking.
2203	*/
2204	return worker && worker->current_pwq->wq == wq;
2205	}
2206
2207	/*
2208	* When queueing an unbound work item to a wq, prefer local CPU if allowed
2209	* by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to
2210	* avoid perturbing sensitive tasks.
2211	*/
2212	static int wq_select_unbound_cpu(int cpu)
2213	{
2214	int new_cpu;
2215
2216	if (likely(!wq_debug_force_rr_cpu)) {
2217	if (cpumask_test_cpu(cpu, wq_unbound_cpumask))
2218	return cpu;
2219	} else {
2220	pr_warn_once("workqueue: round-robin CPU selection forced, expect performance impact\n");
2221	}
2222
2223	new_cpu = __this_cpu_read(wq_rr_cpu_last);
2224	new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask);
2225	if (unlikely(new_cpu >= nr_cpu_ids)) {
2226	new_cpu = cpumask_first_and(wq_unbound_cpumask, cpu_online_mask);
2227	if (unlikely(new_cpu >= nr_cpu_ids))
2228	return cpu;
2229	}
2230	__this_cpu_write(wq_rr_cpu_last, new_cpu);
2231
2232	return new_cpu;
2233	}
2234
2235	static void __queue_work(int cpu, struct workqueue_struct *wq,
2236	struct work_struct *work)
2237	{
2238	struct pool_workqueue *pwq;
2239	struct worker_pool last_pool, pool;
2240	unsigned int work_flags;
2241	unsigned int req_cpu = cpu;
2242
2243	/*
2244	* While a work item is PENDING && off queue, a task trying to
2245	* steal the PENDING will busy-loop waiting for it to either get
2246	* queued or lose PENDING. Grabbing PENDING and queueing should
2247	* happen with IRQ disabled.
2248	*/
2249	lockdep_assert_irqs_disabled();
2250
2251	/*
2252	* For a draining wq, only works from the same workqueue are
2253	* allowed. The __WQ_DESTROYING helps to spot the issue that
2254	* queues a new work item to a wq after destroy_workqueue(wq).
2255	*/
2256	if (unlikely(wq->flags & (__WQ_DESTROYING \| __WQ_DRAINING) &&
2257	WARN_ONCE(!is_chained_work(wq), "workqueue: cannot queue %ps on wq %s\n",
2258	work->func, wq->name))) {
2259	return;
2260	}
2261	rcu_read_lock();
2262	retry:
2263	/* pwq which will be used unless @work is executing elsewhere */
2264	if (req_cpu == WORK_CPU_UNBOUND) {
2265	if (wq->flags & WQ_UNBOUND)
2266	cpu = wq_select_unbound_cpu(raw_smp_processor_id());
2267	else
2268	cpu = raw_smp_processor_id();
2269	}
2270
2271	pwq = rcu_dereference(*per_cpu_ptr(wq->cpu_pwq, cpu));
2272	pool = pwq->pool;
2273
2274	/*
2275	* If @work was previously on a different pool, it might still be
2276	* running there, in which case the work needs to be queued on that
2277	* pool to guarantee non-reentrancy.
2278	*
2279	* For ordered workqueue, work items must be queued on the newest pwq
2280	* for accurate order management. Guaranteed order also guarantees
2281	* non-reentrancy. See the comments above unplug_oldest_pwq().
2282	*/
2283	last_pool = get_work_pool(work);
2284	if (last_pool && last_pool != pool && !(wq->flags & __WQ_ORDERED)) {
2285	struct worker *worker;
2286
2287	raw_spin_lock(&last_pool->lock);
2288
2289	worker = find_worker_executing_work(last_pool, work);
2290
2291	if (worker && worker->current_pwq->wq == wq) {
2292	pwq = worker->current_pwq;
2293	pool = pwq->pool;
2294	WARN_ON_ONCE(pool != last_pool);
2295	} else {
2296	/* meh... not running there, queue here */
2297	raw_spin_unlock(&last_pool->lock);
2298	raw_spin_lock(&pool->lock);
2299	}
2300	} else {
2301	raw_spin_lock(&pool->lock);
2302	}
2303
2304	/*
2305	* pwq is determined and locked. For unbound pools, we could have raced
2306	* with pwq release and it could already be dead. If its refcnt is zero,
2307	* repeat pwq selection. Note that unbound pwqs never die without
2308	* another pwq replacing it in cpu_pwq or while work items are executing
2309	* on it, so the retrying is guaranteed to make forward-progress.
2310	*/
2311	if (unlikely(!pwq->refcnt)) {
2312	if (wq->flags & WQ_UNBOUND) {
2313	raw_spin_unlock(&pool->lock);
2314	cpu_relax();
2315	goto retry;
2316	}
2317	/* oops */
2318	WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
2319	wq->name, cpu);
2320	}
2321
2322	/* pwq determined, queue */
2323	trace_workqueue_queue_work(req_cpu, pwq, work);
2324
2325	if (WARN_ON(!list_empty(&work->entry)))
2326	goto out;
2327
2328	pwq->nr_in_flight[pwq->work_color]++;
2329	work_flags = work_color_to_flags(pwq->work_color);
2330
2331	/*
2332	* Limit the number of concurrently active work items to max_active.
2333	* @work must also queue behind existing inactive work items to maintain
2334	* ordering when max_active changes. See wq_adjust_max_active().
2335	*/
2336	if (list_empty(&pwq->inactive_works) && pwq_tryinc_nr_active(pwq, false)) {
2337	if (list_empty(&pool->worklist))
2338	pool->watchdog_ts = jiffies;
2339
2340	trace_workqueue_activate_work(work);
2341	insert_work(pwq, work, &pool->worklist, work_flags);
2342	kick_pool(pool);
2343	} else {
2344	work_flags \|= WORK_STRUCT_INACTIVE;
2345	insert_work(pwq, work, &pwq->inactive_works, work_flags);
2346	}
2347
2348	out:
2349	raw_spin_unlock(&pool->lock);
2350	rcu_read_unlock();
2351	}
2352
2353	static bool clear_pending_if_disabled(struct work_struct *work)
2354	{
2355	unsigned long data = *work_data_bits(work);
2356	struct work_offq_data offqd;
2357
2358	if (likely((data & WORK_STRUCT_PWQ) \|\|
2359	!(data & WORK_OFFQ_DISABLE_MASK)))
2360	return false;
2361
2362	work_offqd_unpack(&offqd, data);
2363	set_work_pool_and_clear_pending(work, offqd.pool_id,
2364	work_offqd_pack_flags(&offqd));
2365	return true;
2366	}
2367
2368	/**
2369	* queue_work_on - queue work on specific cpu
2370	* @cpu: CPU number to execute work on
2371	* @wq: workqueue to use
2372	* @work: work to queue
2373	*
2374	* We queue the work to a specific CPU, the caller must ensure it
2375	* can't go away. Callers that fail to ensure that the specified
2376	* CPU cannot go away will execute on a randomly chosen CPU.
2377	* But note well that callers specifying a CPU that never has been
2378	* online will get a splat.
2379	*
2380	* Return: %false if @work was already on a queue, %true otherwise.
2381	*/
2382	bool queue_work_on(int cpu, struct workqueue_struct *wq,
2383	struct work_struct *work)
2384	{
2385	bool ret = false;
2386	unsigned long irq_flags;
2387
2388	local_irq_save(irq_flags);
2389
2390	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)) &&
2391	!clear_pending_if_disabled(work)) {
2392	__queue_work(cpu, wq, work);
2393	ret = true;
2394	}
2395
2396	local_irq_restore(irq_flags);
2397	return ret;
2398	}
2399	EXPORT_SYMBOL(queue_work_on);
2400
2401	/**
2402	* select_numa_node_cpu - Select a CPU based on NUMA node
2403	* @node: NUMA node ID that we want to select a CPU from
2404	*
2405	* This function will attempt to find a "random" cpu available on a given
2406	* node. If there are no CPUs available on the given node it will return
2407	* WORK_CPU_UNBOUND indicating that we should just schedule to any
2408	* available CPU if we need to schedule this work.
2409	*/
2410	static int select_numa_node_cpu(int node)
2411	{
2412	int cpu;
2413
2414	/* Delay binding to CPU if node is not valid or online */
2415	if (node < 0 \|\| node >= MAX_NUMNODES \|\| !node_online(node))
2416	return WORK_CPU_UNBOUND;
2417
2418	/* Use local node/cpu if we are already there */
2419	cpu = raw_smp_processor_id();
2420	if (node == cpu_to_node(cpu))
2421	return cpu;
2422
2423	/* Use "random" otherwise know as "first" online CPU of node */
2424	cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask);
2425
2426	/* If CPU is valid return that, otherwise just defer */
2427	return cpu < nr_cpu_ids ? cpu : WORK_CPU_UNBOUND;
2428	}
2429
2430	/**
2431	* queue_work_node - queue work on a "random" cpu for a given NUMA node
2432	* @node: NUMA node that we are targeting the work for
2433	* @wq: workqueue to use
2434	* @work: work to queue
2435	*
2436	* We queue the work to a "random" CPU within a given NUMA node. The basic
2437	* idea here is to provide a way to somehow associate work with a given
2438	* NUMA node.
2439	*
2440	* This function will only make a best effort attempt at getting this onto
2441	* the right NUMA node. If no node is requested or the requested node is
2442	* offline then we just fall back to standard queue_work behavior.
2443	*
2444	* Currently the "random" CPU ends up being the first available CPU in the
2445	* intersection of cpu_online_mask and the cpumask of the node, unless we
2446	* are running on the node. In that case we just use the current CPU.
2447	*
2448	* Return: %false if @work was already on a queue, %true otherwise.
2449	*/
2450	bool queue_work_node(int node, struct workqueue_struct *wq,
2451	struct work_struct *work)
2452	{
2453	unsigned long irq_flags;
2454	bool ret = false;
2455
2456	/*
2457	* This current implementation is specific to unbound workqueues.
2458	* Specifically we only return the first available CPU for a given
2459	* node instead of cycling through individual CPUs within the node.
2460	*
2461	* If this is used with a per-cpu workqueue then the logic in
2462	* workqueue_select_cpu_near would need to be updated to allow for
2463	* some round robin type logic.
2464	*/
2465	WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND));
2466
2467	local_irq_save(irq_flags);
2468
2469	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)) &&
2470	!clear_pending_if_disabled(work)) {
2471	int cpu = select_numa_node_cpu(node);
2472
2473	__queue_work(cpu, wq, work);
2474	ret = true;
2475	}
2476
2477	local_irq_restore(irq_flags);
2478	return ret;
2479	}
2480	EXPORT_SYMBOL_GPL(queue_work_node);
2481
2482	void delayed_work_timer_fn(struct timer_list *t)
2483	{
2484	struct delayed_work *dwork = from_timer(dwork, t, timer);
2485
2486	/* should have been called from irqsafe timer with irq already off */
2487	__queue_work(dwork->cpu, dwork->wq, &dwork->work);
2488	}
2489	EXPORT_SYMBOL(delayed_work_timer_fn);
2490
2491	static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
2492	struct delayed_work *dwork, unsigned long delay)
2493	{
2494	struct timer_list *timer = &dwork->timer;
2495	struct work_struct *work = &dwork->work;
2496
2497	WARN_ON_ONCE(!wq);
2498	WARN_ON_ONCE(timer->function != delayed_work_timer_fn);
2499	WARN_ON_ONCE(timer_pending(timer));
2500	WARN_ON_ONCE(!list_empty(&work->entry));
2501
2502	/*
2503	* If @delay is 0, queue @dwork->work immediately. This is for
2504	* both optimization and correctness. The earliest @timer can
2505	* expire is on the closest next tick and delayed_work users depend
2506	* on that there's no such delay when @delay is 0.
2507	*/
2508	if (!delay) {
2509	__queue_work(cpu, wq, &dwork->work);
2510	return;
2511	}
2512
2513	WARN_ON_ONCE(cpu != WORK_CPU_UNBOUND && !cpu_online(cpu));
2514	dwork->wq = wq;
2515	dwork->cpu = cpu;
2516	timer->expires = jiffies + delay;
2517
2518	if (housekeeping_enabled(HK_TYPE_TIMER)) {
2519	/* If the current cpu is a housekeeping cpu, use it. */
2520	cpu = smp_processor_id();
2521	if (!housekeeping_test_cpu(cpu, HK_TYPE_TIMER))
2522	cpu = housekeeping_any_cpu(HK_TYPE_TIMER);
2523	add_timer_on(timer, cpu);
2524	} else {
2525	if (likely(cpu == WORK_CPU_UNBOUND))
2526	add_timer_global(timer);
2527	else
2528	add_timer_on(timer, cpu);
2529	}
2530	}
2531
2532	/**
2533	* queue_delayed_work_on - queue work on specific CPU after delay
2534	* @cpu: CPU number to execute work on
2535	* @wq: workqueue to use
2536	* @dwork: work to queue
2537	* @delay: number of jiffies to wait before queueing
2538	*
2539	* We queue the delayed_work to a specific CPU, for non-zero delays the
2540	* caller must ensure it is online and can't go away. Callers that fail
2541	* to ensure this, may get @dwork->timer queued to an offlined CPU and
2542	* this will prevent queueing of @dwork->work unless the offlined CPU
2543	* becomes online again.
2544	*
2545	* Return: %false if @work was already on a queue, %true otherwise. If
2546	* @delay is zero and @dwork is idle, it will be scheduled for immediate
2547	* execution.
2548	*/
2549	bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
2550	struct delayed_work *dwork, unsigned long delay)
2551	{
2552	struct work_struct *work = &dwork->work;
2553	bool ret = false;
2554	unsigned long irq_flags;
2555
2556	/* read the comment in __queue_work() */
2557	local_irq_save(irq_flags);
2558
2559	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)) &&
2560	!clear_pending_if_disabled(work)) {
2561	__queue_delayed_work(cpu, wq, dwork, delay);
2562	ret = true;
2563	}
2564
2565	local_irq_restore(irq_flags);
2566	return ret;
2567	}
2568	EXPORT_SYMBOL(queue_delayed_work_on);
2569
2570	/**
2571	* mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
2572	* @cpu: CPU number to execute work on
2573	* @wq: workqueue to use
2574	* @dwork: work to queue
2575	* @delay: number of jiffies to wait before queueing
2576	*
2577	* If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
2578	* modify @dwork's timer so that it expires after @delay. If @delay is
2579	* zero, @work is guaranteed to be scheduled immediately regardless of its
2580	* current state.
2581	*
2582	* Return: %false if @dwork was idle and queued, %true if @dwork was
2583	* pending and its timer was modified.
2584	*
2585	* This function is safe to call from any context including IRQ handler.
2586	* See try_to_grab_pending() for details.
2587	*/
2588	bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
2589	struct delayed_work *dwork, unsigned long delay)
2590	{
2591	unsigned long irq_flags;
2592	bool ret;
2593
2594	ret = work_grab_pending(&dwork->work, WORK_CANCEL_DELAYED, &irq_flags);
2595
2596	if (!clear_pending_if_disabled(&dwork->work))
2597	__queue_delayed_work(cpu, wq, dwork, delay);
2598
2599	local_irq_restore(irq_flags);
2600	return ret;
2601	}
2602	EXPORT_SYMBOL_GPL(mod_delayed_work_on);
2603
2604	static void rcu_work_rcufn(struct rcu_head *rcu)
2605	{
2606	struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu);
2607
2608	/* read the comment in __queue_work() */
2609	local_irq_disable();
2610	__queue_work(WORK_CPU_UNBOUND, rwork->wq, &rwork->work);
2611	local_irq_enable();
2612	}
2613
2614	/**
2615	* queue_rcu_work - queue work after a RCU grace period
2616	* @wq: workqueue to use
2617	* @rwork: work to queue
2618	*
2619	* Return: %false if @rwork was already pending, %true otherwise. Note
2620	* that a full RCU grace period is guaranteed only after a %true return.
2621	* While @rwork is guaranteed to be executed after a %false return, the
2622	* execution may happen before a full RCU grace period has passed.
2623	*/
2624	bool queue_rcu_work(struct workqueue_struct wq, struct rcu_work rwork)
2625	{
2626	struct work_struct *work = &rwork->work;
2627
2628	/*
2629	* rcu_work can't be canceled or disabled. Warn if the user reached
2630	* inside @rwork and disabled the inner work.
2631	*/
2632	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)) &&
2633	!WARN_ON_ONCE(clear_pending_if_disabled(work))) {
2634	rwork->wq = wq;
2635	call_rcu_hurry(&rwork->rcu, rcu_work_rcufn);
2636	return true;
2637	}
2638
2639	return false;
2640	}
2641	EXPORT_SYMBOL(queue_rcu_work);
2642
2643	static struct worker *alloc_worker(int node)
2644	{
2645	struct worker *worker;
2646
2647	worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node);
2648	if (worker) {
2649	INIT_LIST_HEAD(&worker->entry);
2650	INIT_LIST_HEAD(&worker->scheduled);
2651	INIT_LIST_HEAD(&worker->node);
2652	/* on creation a worker is in !idle && prep state */
2653	worker->flags = WORKER_PREP;
2654	}
2655	return worker;
2656	}
2657
2658	static cpumask_t pool_allowed_cpus(struct worker_pool pool)
2659	{
2660	if (pool->cpu < 0 && pool->attrs->affn_strict)
2661	return pool->attrs->__pod_cpumask;
2662	else
2663	return pool->attrs->cpumask;
2664	}
2665
2666	/**
2667	* worker_attach_to_pool() - attach a worker to a pool
2668	* @worker: worker to be attached
2669	* @pool: the target pool
2670	*
2671	* Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and
2672	* cpu-binding of @worker are kept coordinated with the pool across
2673	* cpu-[un]hotplugs.
2674	*/
2675	static void worker_attach_to_pool(struct worker *worker,
2676	struct worker_pool *pool)
2677	{
2678	mutex_lock(&wq_pool_attach_mutex);
2679
2680	/*
2681	* The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains stable
2682	* across this function. See the comments above the flag definition for
2683	* details. BH workers are, while per-CPU, always DISASSOCIATED.
2684	*/
2685	if (pool->flags & POOL_DISASSOCIATED) {
2686	worker->flags \|= WORKER_UNBOUND;
2687	} else {
2688	WARN_ON_ONCE(pool->flags & POOL_BH);
2689	kthread_set_per_cpu(worker->task, pool->cpu);
2690	}
2691
2692	if (worker->rescue_wq)
2693	set_cpus_allowed_ptr(worker->task, pool_allowed_cpus(pool));
2694
2695	list_add_tail(&worker->node, &pool->workers);
2696	worker->pool = pool;
2697
2698	mutex_unlock(&wq_pool_attach_mutex);
2699	}
2700
2701	static void unbind_worker(struct worker *worker)
2702	{
2703	lockdep_assert_held(&wq_pool_attach_mutex);
2704
2705	kthread_set_per_cpu(worker->task, -1);
2706	if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask))
2707	WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0);
2708	else
2709	WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0);
2710	}
2711
2712
2713	static void detach_worker(struct worker *worker)
2714	{
2715	lockdep_assert_held(&wq_pool_attach_mutex);
2716
2717	unbind_worker(worker);
2718	list_del(&worker->node);
2719	}
2720
2721	/**
2722	* worker_detach_from_pool() - detach a worker from its pool
2723	* @worker: worker which is attached to its pool
2724	*
2725	* Undo the attaching which had been done in worker_attach_to_pool(). The
2726	* caller worker shouldn't access to the pool after detached except it has
2727	* other reference to the pool.
2728	*/
2729	static void worker_detach_from_pool(struct worker *worker)
2730	{
2731	struct worker_pool *pool = worker->pool;
2732
2733	/* there is one permanent BH worker per CPU which should never detach */
2734	WARN_ON_ONCE(pool->flags & POOL_BH);
2735
2736	mutex_lock(&wq_pool_attach_mutex);
2737	detach_worker(worker);
2738	worker->pool = NULL;
2739	mutex_unlock(&wq_pool_attach_mutex);
2740
2741	/* clear leftover flags without pool->lock after it is detached */
2742	worker->flags &= ~(WORKER_UNBOUND \| WORKER_REBOUND);
2743	}
2744
2745	static int format_worker_id(char buf, size_t size, struct worker worker,
2746	struct worker_pool *pool)
2747	{
2748	if (worker->rescue_wq)
2749	return scnprintf(buf, size, "kworker/R-%s",
2750	worker->rescue_wq->name);
2751
2752	if (pool) {
2753	if (pool->cpu >= 0)
2754	return scnprintf(buf, size, "kworker/%d:%d%s",
2755	pool->cpu, worker->id,
2756	pool->attrs->nice < 0 ? "H" : "");
2757	else
2758	return scnprintf(buf, size, "kworker/u%d:%d",
2759	pool->id, worker->id);
2760	} else {
2761	return scnprintf(buf, size, "kworker/dying");
2762	}
2763	}
2764
2765	/**
2766	* create_worker - create a new workqueue worker
2767	* @pool: pool the new worker will belong to
2768	*
2769	* Create and start a new worker which is attached to @pool.
2770	*
2771	* CONTEXT:
2772	* Might sleep. Does GFP_KERNEL allocations.
2773	*
2774	* Return:
2775	* Pointer to the newly created worker.
2776	*/
2777	static struct worker create_worker(struct worker_pool pool)
2778	{
2779	struct worker *worker;
2780	int id;
2781
2782	/* ID is needed to determine kthread name */
2783	id = ida_alloc(&pool->worker_ida, GFP_KERNEL);
2784	if (id < 0) {
2785	pr_err_once("workqueue: Failed to allocate a worker ID: %pe\n",
2786	ERR_PTR(id));
2787	return NULL;
2788	}
2789
2790	worker = alloc_worker(pool->node);
2791	if (!worker) {
2792	pr_err_once("workqueue: Failed to allocate a worker\n");
2793	goto fail;
2794	}
2795
2796	worker->id = id;
2797
2798	if (!(pool->flags & POOL_BH)) {
2799	char id_buf[WORKER_ID_LEN];
2800
2801	format_worker_id(id_buf, sizeof(id_buf), worker, pool);
2802	worker->task = kthread_create_on_node(worker_thread, worker,
2803	pool->node, "%s", id_buf);
2804	if (IS_ERR(worker->task)) {
2805	if (PTR_ERR(worker->task) == -EINTR) {
2806	pr_err("workqueue: Interrupted when creating a worker thread \"%s\"\n",
2807	id_buf);
2808	} else {
2809	pr_err_once("workqueue: Failed to create a worker thread: %pe",
2810	worker->task);
2811	}
2812	goto fail;
2813	}
2814
2815	set_user_nice(worker->task, pool->attrs->nice);
2816	kthread_bind_mask(worker->task, pool_allowed_cpus(pool));
2817	}
2818
2819	/* successful, attach the worker to the pool */
2820	worker_attach_to_pool(worker, pool);
2821
2822	/* start the newly created worker */
2823	raw_spin_lock_irq(&pool->lock);
2824
2825	worker->pool->nr_workers++;
2826	worker_enter_idle(worker);
2827
2828	/*
2829	* @worker is waiting on a completion in kthread() and will trigger hung
2830	* check if not woken up soon. As kick_pool() is noop if @pool is empty,
2831	* wake it up explicitly.
2832	*/
2833	if (worker->task)
2834	wake_up_process(worker->task);
2835
2836	raw_spin_unlock_irq(&pool->lock);
2837
2838	return worker;
2839
2840	fail:
2841	ida_free(&pool->worker_ida, id);
2842	kfree(worker);
2843	return NULL;
2844	}
2845
2846	static void detach_dying_workers(struct list_head *cull_list)
2847	{
2848	struct worker *worker;
2849
2850	list_for_each_entry(worker, cull_list, entry)
2851	detach_worker(worker);
2852	}
2853
2854	static void reap_dying_workers(struct list_head *cull_list)
2855	{
2856	struct worker worker, tmp;
2857
2858	list_for_each_entry_safe(worker, tmp, cull_list, entry) {
2859	list_del_init(&worker->entry);
2860	kthread_stop_put(worker->task);
2861	kfree(worker);
2862	}
2863	}
2864
2865	/**
2866	* set_worker_dying - Tag a worker for destruction
2867	* @worker: worker to be destroyed
2868	* @list: transfer worker away from its pool->idle_list and into list
2869	*
2870	* Tag @worker for destruction and adjust @pool stats accordingly. The worker
2871	* should be idle.
2872	*
2873	* CONTEXT:
2874	* raw_spin_lock_irq(pool->lock).
2875	*/
2876	static void set_worker_dying(struct worker worker, struct list_head list)
2877	{
2878	struct worker_pool *pool = worker->pool;
2879
2880	lockdep_assert_held(&pool->lock);
2881	lockdep_assert_held(&wq_pool_attach_mutex);
2882
2883	/* sanity check frenzy */
2884	if (WARN_ON(worker->current_work) \|\|
2885	WARN_ON(!list_empty(&worker->scheduled)) \|\|
2886	WARN_ON(!(worker->flags & WORKER_IDLE)))
2887	return;
2888
2889	pool->nr_workers--;
2890	pool->nr_idle--;
2891
2892	worker->flags \|= WORKER_DIE;
2893
2894	list_move(&worker->entry, list);
2895
2896	/* get an extra task struct reference for later kthread_stop_put() */
2897	get_task_struct(worker->task);
2898	}
2899
2900	/**
2901	* idle_worker_timeout - check if some idle workers can now be deleted.
2902	* @t: The pool's idle_timer that just expired
2903	*
2904	* The timer is armed in worker_enter_idle(). Note that it isn't disarmed in
2905	* worker_leave_idle(), as a worker flicking between idle and active while its
2906	* pool is at the too_many_workers() tipping point would cause too much timer
2907	* housekeeping overhead. Since IDLE_WORKER_TIMEOUT is long enough, we just let
2908	* it expire and re-evaluate things from there.
2909	*/
2910	static void idle_worker_timeout(struct timer_list *t)
2911	{
2912	struct worker_pool *pool = from_timer(pool, t, idle_timer);
2913	bool do_cull = false;
2914
2915	if (work_pending(&pool->idle_cull_work))
2916	return;
2917
2918	raw_spin_lock_irq(&pool->lock);
2919
2920	if (too_many_workers(pool)) {
2921	struct worker *worker;
2922	unsigned long expires;
2923
2924	/* idle_list is kept in LIFO order, check the last one */
2925	worker = list_last_entry(&pool->idle_list, struct worker, entry);
2926	expires = worker->last_active + IDLE_WORKER_TIMEOUT;
2927	do_cull = !time_before(jiffies, expires);
2928
2929	if (!do_cull)
2930	mod_timer(&pool->idle_timer, expires);
2931	}
2932	raw_spin_unlock_irq(&pool->lock);
2933
2934	if (do_cull)
2935	queue_work(system_unbound_wq, &pool->idle_cull_work);
2936	}
2937
2938	/**
2939	* idle_cull_fn - cull workers that have been idle for too long.
2940	* @work: the pool's work for handling these idle workers
2941	*
2942	* This goes through a pool's idle workers and gets rid of those that have been
2943	* idle for at least IDLE_WORKER_TIMEOUT seconds.
2944	*
2945	* We don't want to disturb isolated CPUs because of a pcpu kworker being
2946	* culled, so this also resets worker affinity. This requires a sleepable
2947	* context, hence the split between timer callback and work item.
2948	*/
2949	static void idle_cull_fn(struct work_struct *work)
2950	{
2951	struct worker_pool *pool = container_of(work, struct worker_pool, idle_cull_work);
2952	LIST_HEAD(cull_list);
2953
2954	/*
2955	* Grabbing wq_pool_attach_mutex here ensures an already-running worker
2956	* cannot proceed beyong set_pf_worker() in its self-destruct path.
2957	* This is required as a previously-preempted worker could run after
2958	* set_worker_dying() has happened but before detach_dying_workers() did.
2959	*/
2960	mutex_lock(&wq_pool_attach_mutex);
2961	raw_spin_lock_irq(&pool->lock);
2962
2963	while (too_many_workers(pool)) {
2964	struct worker *worker;
2965	unsigned long expires;
2966
2967	worker = list_last_entry(&pool->idle_list, struct worker, entry);
2968	expires = worker->last_active + IDLE_WORKER_TIMEOUT;
2969
2970	if (time_before(jiffies, expires)) {
2971	mod_timer(&pool->idle_timer, expires);
2972	break;
2973	}
2974
2975	set_worker_dying(worker, &cull_list);
2976	}
2977
2978	raw_spin_unlock_irq(&pool->lock);
2979	detach_dying_workers(&cull_list);
2980	mutex_unlock(&wq_pool_attach_mutex);
2981
2982	reap_dying_workers(&cull_list);
2983	}
2984
2985	static void send_mayday(struct work_struct *work)
2986	{
2987	struct pool_workqueue *pwq = get_work_pwq(work);
2988	struct workqueue_struct *wq = pwq->wq;
2989
2990	lockdep_assert_held(&wq_mayday_lock);
2991
2992	if (!wq->rescuer)
2993	return;
2994
2995	/* mayday mayday mayday */
2996	if (list_empty(&pwq->mayday_node)) {
2997	/*
2998	* If @pwq is for an unbound wq, its base ref may be put at
2999	* any time due to an attribute change. Pin @pwq until the
3000	* rescuer is done with it.
3001	*/
3002	get_pwq(pwq);
3003	list_add_tail(&pwq->mayday_node, &wq->maydays);
3004	wake_up_process(wq->rescuer->task);
3005	pwq->stats[PWQ_STAT_MAYDAY]++;
3006	}
3007	}
3008
3009	static void pool_mayday_timeout(struct timer_list *t)
3010	{
3011	struct worker_pool *pool = from_timer(pool, t, mayday_timer);
3012	struct work_struct *work;
3013
3014	raw_spin_lock_irq(&pool->lock);
3015	raw_spin_lock(&wq_mayday_lock); /* for wq->maydays */
3016
3017	if (need_to_create_worker(pool)) {
3018	/*
3019	* We've been trying to create a new worker but
3020	* haven't been successful. We might be hitting an
3021	* allocation deadlock. Send distress signals to
3022	* rescuers.
3023	*/
3024	list_for_each_entry(work, &pool->worklist, entry)
3025	send_mayday(work);
3026	}
3027
3028	raw_spin_unlock(&wq_mayday_lock);
3029	raw_spin_unlock_irq(&pool->lock);
3030
3031	mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
3032	}
3033
3034	/**
3035	* maybe_create_worker - create a new worker if necessary
3036	* @pool: pool to create a new worker for
3037	*
3038	* Create a new worker for @pool if necessary. @pool is guaranteed to
3039	* have at least one idle worker on return from this function. If
3040	* creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
3041	* sent to all rescuers with works scheduled on @pool to resolve
3042	* possible allocation deadlock.
3043	*
3044	* On return, need_to_create_worker() is guaranteed to be %false and
3045	* may_start_working() %true.
3046	*
3047	* LOCKING:
3048	* raw_spin_lock_irq(pool->lock) which may be released and regrabbed
3049	* multiple times. Does GFP_KERNEL allocations. Called only from
3050	* manager.
3051	*/
3052	static void maybe_create_worker(struct worker_pool *pool)
3053	__releases(&pool->lock)
3054	__acquires(&pool->lock)
3055	{
3056	restart:
3057	raw_spin_unlock_irq(&pool->lock);
3058
3059	/* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
3060	mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
3061
3062	while (true) {
3063	if (create_worker(pool) \|\| !need_to_create_worker(pool))
3064	break;
3065
3066	schedule_timeout_interruptible(CREATE_COOLDOWN);
3067
3068	if (!need_to_create_worker(pool))
3069	break;
3070	}
3071
3072	timer_delete_sync(&pool->mayday_timer);
3073	raw_spin_lock_irq(&pool->lock);
3074	/*
3075	* This is necessary even after a new worker was just successfully
3076	* created as @pool->lock was dropped and the new worker might have
3077	* already become busy.
3078	*/
3079	if (need_to_create_worker(pool))
3080	goto restart;
3081	}
3082
3083	/**
3084	* manage_workers - manage worker pool
3085	* @worker: self
3086	*
3087	* Assume the manager role and manage the worker pool @worker belongs
3088	* to. At any given time, there can be only zero or one manager per
3089	* pool. The exclusion is handled automatically by this function.
3090	*
3091	* The caller can safely start processing works on false return. On
3092	* true return, it's guaranteed that need_to_create_worker() is false
3093	* and may_start_working() is true.
3094	*
3095	* CONTEXT:
3096	* raw_spin_lock_irq(pool->lock) which may be released and regrabbed
3097	* multiple times. Does GFP_KERNEL allocations.
3098	*
3099	* Return:
3100	* %false if the pool doesn't need management and the caller can safely
3101	* start processing works, %true if management function was performed and
3102	* the conditions that the caller verified before calling the function may
3103	* no longer be true.
3104	*/
3105	static bool manage_workers(struct worker *worker)
3106	{
3107	struct worker_pool *pool = worker->pool;
3108
3109	if (pool->flags & POOL_MANAGER_ACTIVE)
3110	return false;
3111
3112	pool->flags \|= POOL_MANAGER_ACTIVE;
3113	pool->manager = worker;
3114
3115	maybe_create_worker(pool);
3116
3117	pool->manager = NULL;
3118	pool->flags &= ~POOL_MANAGER_ACTIVE;
3119	rcuwait_wake_up(&manager_wait);
3120	return true;
3121	}
3122
3123	/**
3124	* process_one_work - process single work
3125	* @worker: self
3126	* @work: work to process
3127	*
3128	* Process @work. This function contains all the logics necessary to
3129	* process a single work including synchronization against and
3130	* interaction with other workers on the same cpu, queueing and
3131	* flushing. As long as context requirement is met, any worker can
3132	* call this function to process a work.
3133	*
3134	* CONTEXT:
3135	* raw_spin_lock_irq(pool->lock) which is released and regrabbed.
3136	*/
3137	static void process_one_work(struct worker worker, struct work_struct work)
3138	__releases(&pool->lock)
3139	__acquires(&pool->lock)
3140	{
3141	struct pool_workqueue *pwq = get_work_pwq(work);
3142	struct worker_pool *pool = worker->pool;
3143	unsigned long work_data;
3144	int lockdep_start_depth, rcu_start_depth;
3145	bool bh_draining = pool->flags & POOL_BH_DRAINING;
3146	#ifdef CONFIG_LOCKDEP
3147	/*
3148	* It is permissible to free the struct work_struct from
3149	* inside the function that is called from it, this we need to
3150	* take into account for lockdep too. To avoid bogus "held
3151	* lock freed" warnings as well as problems when looking into
3152	* work->lockdep_map, make a copy and use that here.
3153	*/
3154	struct lockdep_map lockdep_map;
3155
3156	lockdep_copy_map(&lockdep_map, &work->lockdep_map);
3157	#endif
3158	/* ensure we're on the correct CPU */
3159	WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
3160	raw_smp_processor_id() != pool->cpu);
3161
3162	/* claim and dequeue */
3163	debug_work_deactivate(work);
3164	hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work);
3165	worker->current_work = work;
3166	worker->current_func = work->func;
3167	worker->current_pwq = pwq;
3168	if (worker->task)
3169	worker->current_at = worker->task->se.sum_exec_runtime;
3170	work_data = *work_data_bits(work);
3171	worker->current_color = get_work_color(work_data);
3172
3173	/*
3174	* Record wq name for cmdline and debug reporting, may get
3175	* overridden through set_worker_desc().
3176	*/
3177	strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN);
3178
3179	list_del_init(&work->entry);
3180
3181	/*
3182	* CPU intensive works don't participate in concurrency management.
3183	* They're the scheduler's responsibility. This takes @worker out
3184	* of concurrency management and the next code block will chain
3185	* execution of the pending work items.
3186	*/
3187	if (unlikely(pwq->wq->flags & WQ_CPU_INTENSIVE))
3188	worker_set_flags(worker, WORKER_CPU_INTENSIVE);
3189
3190	/*
3191	* Kick @pool if necessary. It's always noop for per-cpu worker pools
3192	* since nr_running would always be >= 1 at this point. This is used to
3193	* chain execution of the pending work items for WORKER_NOT_RUNNING
3194	* workers such as the UNBOUND and CPU_INTENSIVE ones.
3195	*/
3196	kick_pool(pool);
3197
3198	/*
3199	* Record the last pool and clear PENDING which should be the last
3200	* update to @work. Also, do this inside @pool->lock so that
3201	* PENDING and queued state changes happen together while IRQ is
3202	* disabled.
3203	*/
3204	set_work_pool_and_clear_pending(work, pool->id, pool_offq_flags(pool));
3205
3206	pwq->stats[PWQ_STAT_STARTED]++;
3207	raw_spin_unlock_irq(&pool->lock);
3208
3209	rcu_start_depth = rcu_preempt_depth();
3210	lockdep_start_depth = lockdep_depth(current);
3211	/* see drain_dead_softirq_workfn() */
3212	if (!bh_draining)
3213	lock_map_acquire(pwq->wq->lockdep_map);
3214	lock_map_acquire(&lockdep_map);
3215	/*
3216	* Strictly speaking we should mark the invariant state without holding
3217	* any locks, that is, before these two lock_map_acquire()'s.
3218	*
3219	* However, that would result in:
3220	*
3221	* A(W1)
3222	* WFC(C)
3223	* A(W1)
3224	* C(C)
3225	*
3226	* Which would create W1->C->W1 dependencies, even though there is no
3227	* actual deadlock possible. There are two solutions, using a
3228	* read-recursive acquire on the work(queue) 'locks', but this will then
3229	* hit the lockdep limitation on recursive locks, or simply discard
3230	* these locks.
3231	*
3232	* AFAICT there is no possible deadlock scenario between the
3233	* flush_work() and complete() primitives (except for single-threaded
3234	* workqueues), so hiding them isn't a problem.
3235	*/
3236	lockdep_invariant_state(true);
3237	trace_workqueue_execute_start(work);
3238	worker->current_func(work);
3239	/*
3240	* While we must be careful to not use "work" after this, the trace
3241	* point will only record its address.
3242	*/
3243	trace_workqueue_execute_end(work, worker->current_func);
3244	pwq->stats[PWQ_STAT_COMPLETED]++;
3245	lock_map_release(&lockdep_map);
3246	if (!bh_draining)
3247	lock_map_release(pwq->wq->lockdep_map);
3248
3249	if (unlikely((worker->task && in_atomic()) \|\|
3250	lockdep_depth(current) != lockdep_start_depth \|\|
3251	rcu_preempt_depth() != rcu_start_depth)) {
3252	pr_err("BUG: workqueue leaked atomic, lock or RCU: %s[%d]\n"
3253	" preempt=0x%08x lock=%d->%d RCU=%d->%d workfn=%ps\n",
3254	current->comm, task_pid_nr(current), preempt_count(),
3255	lockdep_start_depth, lockdep_depth(current),
3256	rcu_start_depth, rcu_preempt_depth(),
3257	worker->current_func);
3258	debug_show_held_locks(current);
3259	dump_stack();
3260	}
3261
3262	/*
3263	* The following prevents a kworker from hogging CPU on !PREEMPTION
3264	* kernels, where a requeueing work item waiting for something to
3265	* happen could deadlock with stop_machine as such work item could
3266	* indefinitely requeue itself while all other CPUs are trapped in
3267	* stop_machine. At the same time, report a quiescent RCU state so
3268	* the same condition doesn't freeze RCU.
3269	*/
3270	if (worker->task)
3271	cond_resched();
3272
3273	raw_spin_lock_irq(&pool->lock);
3274
3275	/*
3276	* In addition to %WQ_CPU_INTENSIVE, @worker may also have been marked
3277	* CPU intensive by wq_worker_tick() if @work hogged CPU longer than
3278	* wq_cpu_intensive_thresh_us. Clear it.
3279	*/
3280	worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
3281
3282	/* tag the worker for identification in schedule() */
3283	worker->last_func = worker->current_func;
3284
3285	/* we're done with it, release */
3286	hash_del(&worker->hentry);
3287	worker->current_work = NULL;
3288	worker->current_func = NULL;
3289	worker->current_pwq = NULL;
3290	worker->current_color = INT_MAX;
3291
3292	/* must be the last step, see the function comment */
3293	pwq_dec_nr_in_flight(pwq, work_data);
3294	}
3295
3296	/**
3297	* process_scheduled_works - process scheduled works
3298	* @worker: self
3299	*
3300	* Process all scheduled works. Please note that the scheduled list
3301	* may change while processing a work, so this function repeatedly
3302	* fetches a work from the top and executes it.
3303	*
3304	* CONTEXT:
3305	* raw_spin_lock_irq(pool->lock) which may be released and regrabbed
3306	* multiple times.
3307	*/
3308	static void process_scheduled_works(struct worker *worker)
3309	{
3310	struct work_struct *work;
3311	bool first = true;
3312
3313	while ((work = list_first_entry_or_null(&worker->scheduled,
3314	struct work_struct, entry))) {
3315	if (first) {
3316	worker->pool->watchdog_ts = jiffies;
3317	first = false;
3318	}
3319	process_one_work(worker, work);
3320	}
3321	}
3322
3323	static void set_pf_worker(bool val)
3324	{
3325	mutex_lock(&wq_pool_attach_mutex);
3326	if (val)
3327	current->flags \|= PF_WQ_WORKER;
3328	else
3329	current->flags &= ~PF_WQ_WORKER;
3330	mutex_unlock(&wq_pool_attach_mutex);
3331	}
3332
3333	/**
3334	* worker_thread - the worker thread function
3335	* @__worker: self
3336	*
3337	* The worker thread function. All workers belong to a worker_pool -
3338	* either a per-cpu one or dynamic unbound one. These workers process all
3339	* work items regardless of their specific target workqueue. The only
3340	* exception is work items which belong to workqueues with a rescuer which
3341	* will be explained in rescuer_thread().
3342	*
3343	* Return: 0
3344	*/
3345	static int worker_thread(void *__worker)
3346	{
3347	struct worker *worker = __worker;
3348	struct worker_pool *pool = worker->pool;
3349
3350	/* tell the scheduler that this is a workqueue worker */
3351	set_pf_worker(true);
3352	woke_up:
3353	raw_spin_lock_irq(&pool->lock);
3354
3355	/* am I supposed to die? */
3356	if (unlikely(worker->flags & WORKER_DIE)) {
3357	raw_spin_unlock_irq(&pool->lock);
3358	set_pf_worker(false);
3359	/*
3360	* The worker is dead and PF_WQ_WORKER is cleared, worker->pool
3361	* shouldn't be accessed, reset it to NULL in case otherwise.
3362	*/
3363	worker->pool = NULL;
3364	ida_free(&pool->worker_ida, worker->id);
3365	return 0;
3366	}
3367
3368	worker_leave_idle(worker);
3369	recheck:
3370	/* no more worker necessary? */
3371	if (!need_more_worker(pool))
3372	goto sleep;
3373
3374	/* do we need to manage? */
3375	if (unlikely(!may_start_working(pool)) && manage_workers(worker))
3376	goto recheck;
3377
3378	/*
3379	* ->scheduled list can only be filled while a worker is
3380	* preparing to process a work or actually processing it.
3381	* Make sure nobody diddled with it while I was sleeping.
3382	*/
3383	WARN_ON_ONCE(!list_empty(&worker->scheduled));
3384
3385	/*
3386	* Finish PREP stage. We're guaranteed to have at least one idle
3387	* worker or that someone else has already assumed the manager
3388	* role. This is where @worker starts participating in concurrency
3389	* management if applicable and concurrency management is restored
3390	* after being rebound. See rebind_workers() for details.
3391	*/
3392	worker_clr_flags(worker, WORKER_PREP \| WORKER_REBOUND);
3393
3394	do {
3395	struct work_struct *work =
3396	list_first_entry(&pool->worklist,
3397	struct work_struct, entry);
3398
3399	if (assign_work(work, worker, NULL))
3400	process_scheduled_works(worker);
3401	} while (keep_working(pool));
3402
3403	worker_set_flags(worker, WORKER_PREP);
3404	sleep:
3405	/*
3406	* pool->lock is held and there's no work to process and no need to
3407	* manage, sleep. Workers are woken up only while holding
3408	* pool->lock or from local cpu, so setting the current state
3409	* before releasing pool->lock is enough to prevent losing any
3410	* event.
3411	*/
3412	worker_enter_idle(worker);
3413	__set_current_state(TASK_IDLE);
3414	raw_spin_unlock_irq(&pool->lock);
3415	schedule();
3416	goto woke_up;
3417	}
3418
3419	/**
3420	* rescuer_thread - the rescuer thread function
3421	* @__rescuer: self
3422	*
3423	* Workqueue rescuer thread function. There's one rescuer for each
3424	* workqueue which has WQ_MEM_RECLAIM set.
3425	*
3426	* Regular work processing on a pool may block trying to create a new
3427	* worker which uses GFP_KERNEL allocation which has slight chance of
3428	* developing into deadlock if some works currently on the same queue
3429	* need to be processed to satisfy the GFP_KERNEL allocation. This is
3430	* the problem rescuer solves.
3431	*
3432	* When such condition is possible, the pool summons rescuers of all
3433	* workqueues which have works queued on the pool and let them process
3434	* those works so that forward progress can be guaranteed.
3435	*
3436	* This should happen rarely.
3437	*
3438	* Return: 0
3439	*/
3440	static int rescuer_thread(void *__rescuer)
3441	{
3442	struct worker *rescuer = __rescuer;
3443	struct workqueue_struct *wq = rescuer->rescue_wq;
3444	bool should_stop;
3445
3446	set_user_nice(current, RESCUER_NICE_LEVEL);
3447
3448	/*
3449	* Mark rescuer as worker too. As WORKER_PREP is never cleared, it
3450	* doesn't participate in concurrency management.
3451	*/
3452	set_pf_worker(true);
3453	repeat:
3454	set_current_state(TASK_IDLE);
3455
3456	/*
3457	* By the time the rescuer is requested to stop, the workqueue
3458	* shouldn't have any work pending, but @wq->maydays may still have
3459	* pwq(s) queued. This can happen by non-rescuer workers consuming
3460	* all the work items before the rescuer got to them. Go through
3461	* @wq->maydays processing before acting on should_stop so that the
3462	* list is always empty on exit.
3463	*/
3464	should_stop = kthread_should_stop();
3465
3466	/* see whether any pwq is asking for help */
3467	raw_spin_lock_irq(&wq_mayday_lock);
3468
3469	while (!list_empty(&wq->maydays)) {
3470	struct pool_workqueue *pwq = list_first_entry(&wq->maydays,
3471	struct pool_workqueue, mayday_node);
3472	struct worker_pool *pool = pwq->pool;
3473	struct work_struct work, n;
3474
3475	__set_current_state(TASK_RUNNING);
3476	list_del_init(&pwq->mayday_node);
3477
3478	raw_spin_unlock_irq(&wq_mayday_lock);
3479
3480	worker_attach_to_pool(rescuer, pool);
3481
3482	raw_spin_lock_irq(&pool->lock);
3483
3484	/*
3485	* Slurp in all works issued via this workqueue and
3486	* process'em.
3487	*/
3488	WARN_ON_ONCE(!list_empty(&rescuer->scheduled));
3489	list_for_each_entry_safe(work, n, &pool->worklist, entry) {
3490	if (get_work_pwq(work) == pwq &&
3491	assign_work(work, rescuer, &n))
3492	pwq->stats[PWQ_STAT_RESCUED]++;
3493	}
3494
3495	if (!list_empty(&rescuer->scheduled)) {
3496	process_scheduled_works(rescuer);
3497
3498	/*
3499	* The above execution of rescued work items could
3500	* have created more to rescue through
3501	* pwq_activate_first_inactive() or chained
3502	* queueing. Let's put @pwq back on mayday list so
3503	* that such back-to-back work items, which may be
3504	* being used to relieve memory pressure, don't
3505	* incur MAYDAY_INTERVAL delay inbetween.
3506	*/
3507	if (pwq->nr_active && need_to_create_worker(pool)) {
3508	raw_spin_lock(&wq_mayday_lock);
3509	/*
3510	* Queue iff we aren't racing destruction
3511	* and somebody else hasn't queued it already.
3512	*/
3513	if (wq->rescuer && list_empty(&pwq->mayday_node)) {
3514	get_pwq(pwq);
3515	list_add_tail(&pwq->mayday_node, &wq->maydays);
3516	}
3517	raw_spin_unlock(&wq_mayday_lock);
3518	}
3519	}
3520
3521	/*
3522	* Leave this pool. Notify regular workers; otherwise, we end up
3523	* with 0 concurrency and stalling the execution.
3524	*/
3525	kick_pool(pool);
3526
3527	raw_spin_unlock_irq(&pool->lock);
3528
3529	worker_detach_from_pool(rescuer);
3530
3531	/*
3532	* Put the reference grabbed by send_mayday(). @pool might
3533	* go away any time after it.
3534	*/
3535	put_pwq_unlocked(pwq);
3536
3537	raw_spin_lock_irq(&wq_mayday_lock);
3538	}
3539
3540	raw_spin_unlock_irq(&wq_mayday_lock);
3541
3542	if (should_stop) {
3543	__set_current_state(TASK_RUNNING);
3544	set_pf_worker(false);
3545	return 0;
3546	}
3547
3548	/* rescuers should never participate in concurrency management */
3549	WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING));
3550	schedule();
3551	goto repeat;
3552	}
3553
3554	static void bh_worker(struct worker *worker)
3555	{
3556	struct worker_pool *pool = worker->pool;
3557	int nr_restarts = BH_WORKER_RESTARTS;
3558	unsigned long end = jiffies + BH_WORKER_JIFFIES;
3559
3560	raw_spin_lock_irq(&pool->lock);
3561	worker_leave_idle(worker);
3562
3563	/*
3564	* This function follows the structure of worker_thread(). See there for
3565	* explanations on each step.
3566	*/
3567	if (!need_more_worker(pool))
3568	goto done;
3569
3570	WARN_ON_ONCE(!list_empty(&worker->scheduled));
3571	worker_clr_flags(worker, WORKER_PREP \| WORKER_REBOUND);
3572
3573	do {
3574	struct work_struct *work =
3575	list_first_entry(&pool->worklist,
3576	struct work_struct, entry);
3577
3578	if (assign_work(work, worker, NULL))
3579	process_scheduled_works(worker);
3580	} while (keep_working(pool) &&
3581	--nr_restarts && time_before(jiffies, end));
3582
3583	worker_set_flags(worker, WORKER_PREP);
3584	done:
3585	worker_enter_idle(worker);
3586	kick_pool(pool);
3587	raw_spin_unlock_irq(&pool->lock);
3588	}
3589
3590	/*
3591	* TODO: Convert all tasklet users to workqueue and use softirq directly.
3592	*
3593	* This is currently called from tasklet[_hi]action() and thus is also called
3594	* whenever there are tasklets to run. Let's do an early exit if there's nothing
3595	* queued. Once conversion from tasklet is complete, the need_more_worker() test
3596	* can be dropped.
3597	*
3598	* After full conversion, we'll add worker->softirq_action, directly use the
3599	* softirq action and obtain the worker pointer from the softirq_action pointer.
3600	*/
3601	void workqueue_softirq_action(bool highpri)
3602	{
3603	struct worker_pool *pool =
3604	&per_cpu(bh_worker_pools, smp_processor_id())[highpri];
3605	if (need_more_worker(pool))
3606	bh_worker(list_first_entry(&pool->workers, struct worker, node));
3607	}
3608
3609	struct wq_drain_dead_softirq_work {
3610	struct work_struct work;
3611	struct worker_pool *pool;
3612	struct completion done;
3613	};
3614
3615	static void drain_dead_softirq_workfn(struct work_struct *work)
3616	{
3617	struct wq_drain_dead_softirq_work *dead_work =
3618	container_of(work, struct wq_drain_dead_softirq_work, work);
3619	struct worker_pool *pool = dead_work->pool;
3620	bool repeat;
3621
3622	/*
3623	* @pool's CPU is dead and we want to execute its still pending work
3624	* items from this BH work item which is running on a different CPU. As
3625	* its CPU is dead, @pool can't be kicked and, as work execution path
3626	* will be nested, a lockdep annotation needs to be suppressed. Mark
3627	* @pool with %POOL_BH_DRAINING for the special treatments.
3628	*/
3629	raw_spin_lock_irq(&pool->lock);
3630	pool->flags \|= POOL_BH_DRAINING;
3631	raw_spin_unlock_irq(&pool->lock);
3632
3633	bh_worker(list_first_entry(&pool->workers, struct worker, node));
3634
3635	raw_spin_lock_irq(&pool->lock);
3636	pool->flags &= ~POOL_BH_DRAINING;
3637	repeat = need_more_worker(pool);
3638	raw_spin_unlock_irq(&pool->lock);
3639
3640	/*
3641	* bh_worker() might hit consecutive execution limit and bail. If there
3642	* still are pending work items, reschedule self and return so that we
3643	* don't hog this CPU's BH.
3644	*/
3645	if (repeat) {
3646	if (pool->attrs->nice == HIGHPRI_NICE_LEVEL)
3647	queue_work(system_bh_highpri_wq, work);
3648	else
3649	queue_work(system_bh_wq, work);
3650	} else {
3651	complete(&dead_work->done);
3652	}
3653	}
3654
3655	/*
3656	* @cpu is dead. Drain the remaining BH work items on the current CPU. It's
3657	* possible to allocate dead_work per CPU and avoid flushing. However, then we
3658	* have to worry about draining overlapping with CPU coming back online or
3659	* nesting (one CPU's dead_work queued on another CPU which is also dead and so
3660	* on). Let's keep it simple and drain them synchronously. These are BH work
3661	* items which shouldn't be requeued on the same pool. Shouldn't take long.
3662	*/
3663	void workqueue_softirq_dead(unsigned int cpu)
3664	{
3665	int i;
3666
3667	for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
3668	struct worker_pool *pool = &per_cpu(bh_worker_pools, cpu)[i];
3669	struct wq_drain_dead_softirq_work dead_work;
3670
3671	if (!need_more_worker(pool))
3672	continue;
3673
3674	INIT_WORK_ONSTACK(&dead_work.work, drain_dead_softirq_workfn);
3675	dead_work.pool = pool;
3676	init_completion(&dead_work.done);
3677
3678	if (pool->attrs->nice == HIGHPRI_NICE_LEVEL)
3679	queue_work(system_bh_highpri_wq, &dead_work.work);
3680	else
3681	queue_work(system_bh_wq, &dead_work.work);
3682
3683	wait_for_completion(&dead_work.done);
3684	destroy_work_on_stack(&dead_work.work);
3685	}
3686	}
3687
3688	/**
3689	* check_flush_dependency - check for flush dependency sanity
3690	* @target_wq: workqueue being flushed
3691	* @target_work: work item being flushed (NULL for workqueue flushes)
3692	* @from_cancel: are we called from the work cancel path
3693	*
3694	* %current is trying to flush the whole @target_wq or @target_work on it.
3695	* If this is not the cancel path (which implies work being flushed is either
3696	* already running, or will not be at all), check if @target_wq doesn't have
3697	* %WQ_MEM_RECLAIM and verify that %current is not reclaiming memory or running
3698	* on a workqueue which doesn't have %WQ_MEM_RECLAIM as that can break forward-
3699	* progress guarantee leading to a deadlock.
3700	*/
3701	static void check_flush_dependency(struct workqueue_struct *target_wq,
3702	struct work_struct *target_work,
3703	bool from_cancel)
3704	{
3705	work_func_t target_func;
3706	struct worker *worker;
3707
3708	if (from_cancel \|\| target_wq->flags & WQ_MEM_RECLAIM)
3709	return;
3710
3711	worker = current_wq_worker();
3712	target_func = target_work ? target_work->func : NULL;
3713
3714	WARN_ONCE(current->flags & PF_MEMALLOC,
3715	"workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps",
3716	current->pid, current->comm, target_wq->name, target_func);
3717	WARN_ONCE(worker && ((worker->current_pwq->wq->flags &
3718	(WQ_MEM_RECLAIM \| __WQ_LEGACY)) == WQ_MEM_RECLAIM),
3719	"workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps",
3720	worker->current_pwq->wq->name, worker->current_func,
3721	target_wq->name, target_func);
3722	}
3723
3724	struct wq_barrier {
3725	struct work_struct work;
3726	struct completion done;
3727	struct task_struct task; / purely informational */
3728	};
3729
3730	static void wq_barrier_func(struct work_struct *work)
3731	{
3732	struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
3733	complete(&barr->done);
3734	}
3735
3736	/**
3737	* insert_wq_barrier - insert a barrier work
3738	* @pwq: pwq to insert barrier into
3739	* @barr: wq_barrier to insert
3740	* @target: target work to attach @barr to
3741	* @worker: worker currently executing @target, NULL if @target is not executing
3742	*
3743	* @barr is linked to @target such that @barr is completed only after
3744	* @target finishes execution. Please note that the ordering
3745	* guarantee is observed only with respect to @target and on the local
3746	* cpu.
3747	*
3748	* Currently, a queued barrier can't be canceled. This is because
3749	* try_to_grab_pending() can't determine whether the work to be
3750	* grabbed is at the head of the queue and thus can't clear LINKED
3751	* flag of the previous work while there must be a valid next work
3752	* after a work with LINKED flag set.
3753	*
3754	* Note that when @worker is non-NULL, @target may be modified
3755	* underneath us, so we can't reliably determine pwq from @target.
3756	*
3757	* CONTEXT:
3758	* raw_spin_lock_irq(pool->lock).
3759	*/
3760	static void insert_wq_barrier(struct pool_workqueue *pwq,
3761	struct wq_barrier *barr,
3762	struct work_struct target, struct worker worker)
3763	{
3764	static __maybe_unused struct lock_class_key bh_key, thr_key;
3765	unsigned int work_flags = 0;
3766	unsigned int work_color;
3767	struct list_head *head;
3768
3769	/*
3770	* debugobject calls are safe here even with pool->lock locked
3771	* as we know for sure that this will not trigger any of the
3772	* checks and call back into the fixup functions where we
3773	* might deadlock.
3774	*
3775	* BH and threaded workqueues need separate lockdep keys to avoid
3776	* spuriously triggering "inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W}
3777	* usage".
3778	*/
3779	INIT_WORK_ONSTACK_KEY(&barr->work, wq_barrier_func,
3780	(pwq->wq->flags & WQ_BH) ? &bh_key : &thr_key);
3781	__set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
3782
3783	init_completion_map(&barr->done, &target->lockdep_map);
3784
3785	barr->task = current;
3786
3787	/* The barrier work item does not participate in nr_active. */
3788	work_flags \|= WORK_STRUCT_INACTIVE;
3789
3790	/*
3791	* If @target is currently being executed, schedule the
3792	* barrier to the worker; otherwise, put it after @target.
3793	*/
3794	if (worker) {
3795	head = worker->scheduled.next;
3796	work_color = worker->current_color;
3797	} else {
3798	unsigned long *bits = work_data_bits(target);
3799
3800	head = target->entry.next;
3801	/* there can already be other linked works, inherit and set */
3802	work_flags \|= *bits & WORK_STRUCT_LINKED;
3803	work_color = get_work_color(*bits);
3804	__set_bit(WORK_STRUCT_LINKED_BIT, bits);
3805	}
3806
3807	pwq->nr_in_flight[work_color]++;
3808	work_flags \|= work_color_to_flags(work_color);
3809
3810	insert_work(pwq, &barr->work, head, work_flags);
3811	}
3812
3813	/**
3814	* flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
3815	* @wq: workqueue being flushed
3816	* @flush_color: new flush color, < 0 for no-op
3817	* @work_color: new work color, < 0 for no-op
3818	*
3819	* Prepare pwqs for workqueue flushing.
3820	*
3821	* If @flush_color is non-negative, flush_color on all pwqs should be
3822	* -1. If no pwq has in-flight commands at the specified color, all
3823	* pwq->flush_color's stay at -1 and %false is returned. If any pwq
3824	* has in flight commands, its pwq->flush_color is set to
3825	* @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
3826	* wakeup logic is armed and %true is returned.
3827	*
3828	* The caller should have initialized @wq->first_flusher prior to
3829	* calling this function with non-negative @flush_color. If
3830	* @flush_color is negative, no flush color update is done and %false
3831	* is returned.
3832	*
3833	* If @work_color is non-negative, all pwqs should have the same
3834	* work_color which is previous to @work_color and all will be
3835	* advanced to @work_color.
3836	*
3837	* CONTEXT:
3838	* mutex_lock(wq->mutex).
3839	*
3840	* Return:
3841	* %true if @flush_color >= 0 and there's something to flush. %false
3842	* otherwise.
3843	*/
3844	static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq,
3845	int flush_color, int work_color)
3846	{
3847	bool wait = false;
3848	struct pool_workqueue *pwq;
3849	struct worker_pool *current_pool = NULL;
3850
3851	if (flush_color >= 0) {
3852	WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush));
3853	atomic_set(&wq->nr_pwqs_to_flush, 1);
3854	}
3855
3856	/*
3857	* For unbound workqueue, pwqs will map to only a few pools.
3858	* Most of the time, pwqs within the same pool will be linked
3859	* sequentially to wq->pwqs by cpu index. So in the majority
3860	* of pwq iters, the pool is the same, only doing lock/unlock
3861	* if the pool has changed. This can largely reduce expensive
3862	* lock operations.
3863	*/
3864	for_each_pwq(pwq, wq) {
3865	if (current_pool != pwq->pool) {
3866	if (likely(current_pool))
3867	raw_spin_unlock_irq(&current_pool->lock);
3868	current_pool = pwq->pool;
3869	raw_spin_lock_irq(&current_pool->lock);
3870	}
3871
3872	if (flush_color >= 0) {
3873	WARN_ON_ONCE(pwq->flush_color != -1);
3874
3875	if (pwq->nr_in_flight[flush_color]) {
3876	pwq->flush_color = flush_color;
3877	atomic_inc(&wq->nr_pwqs_to_flush);
3878	wait = true;
3879	}
3880	}
3881
3882	if (work_color >= 0) {
3883	WARN_ON_ONCE(work_color != work_next_color(pwq->work_color));
3884	pwq->work_color = work_color;
3885	}
3886
3887	}
3888
3889	if (current_pool)
3890	raw_spin_unlock_irq(&current_pool->lock);
3891
3892	if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush))
3893	complete(&wq->first_flusher->done);
3894
3895	return wait;
3896	}
3897
3898	static void touch_wq_lockdep_map(struct workqueue_struct *wq)
3899	{
3900	#ifdef CONFIG_LOCKDEP
3901	if (unlikely(!wq->lockdep_map))
3902	return;
3903
3904	if (wq->flags & WQ_BH)
3905	local_bh_disable();
3906
3907	lock_map_acquire(wq->lockdep_map);
3908	lock_map_release(wq->lockdep_map);
3909
3910	if (wq->flags & WQ_BH)
3911	local_bh_enable();
3912	#endif
3913	}
3914
3915	static void touch_work_lockdep_map(struct work_struct *work,
3916	struct workqueue_struct *wq)
3917	{
3918	#ifdef CONFIG_LOCKDEP
3919	if (wq->flags & WQ_BH)
3920	local_bh_disable();
3921
3922	lock_map_acquire(&work->lockdep_map);
3923	lock_map_release(&work->lockdep_map);
3924
3925	if (wq->flags & WQ_BH)
3926	local_bh_enable();
3927	#endif
3928	}
3929
3930	/**
3931	* __flush_workqueue - ensure that any scheduled work has run to completion.
3932	* @wq: workqueue to flush
3933	*
3934	* This function sleeps until all work items which were queued on entry
3935	* have finished execution, but it is not livelocked by new incoming ones.
3936	*/
3937	void __flush_workqueue(struct workqueue_struct *wq)
3938	{
3939	struct wq_flusher this_flusher = {
3940	.list = LIST_HEAD_INIT(this_flusher.list),
3941	.flush_color = -1,
3942	.done = COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher.done, (*wq->lockdep_map)),
3943	};
3944	int next_color;
3945
3946	if (WARN_ON(!wq_online))
3947	return;
3948
3949	touch_wq_lockdep_map(wq);
3950
3951	mutex_lock(&wq->mutex);
3952
3953	/*
3954	* Start-to-wait phase
3955	*/
3956	next_color = work_next_color(wq->work_color);
3957
3958	if (next_color != wq->flush_color) {
3959	/*
3960	* Color space is not full. The current work_color
3961	* becomes our flush_color and work_color is advanced
3962	* by one.
3963	*/
3964	WARN_ON_ONCE(!list_empty(&wq->flusher_overflow));
3965	this_flusher.flush_color = wq->work_color;
3966	wq->work_color = next_color;
3967
3968	if (!wq->first_flusher) {
3969	/* no flush in progress, become the first flusher */
3970	WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
3971
3972	wq->first_flusher = &this_flusher;
3973
3974	if (!flush_workqueue_prep_pwqs(wq, wq->flush_color,
3975	wq->work_color)) {
3976	/* nothing to flush, done */
3977	wq->flush_color = next_color;
3978	wq->first_flusher = NULL;
3979	goto out_unlock;
3980	}
3981	} else {
3982	/* wait in queue */
3983	WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color);
3984	list_add_tail(&this_flusher.list, &wq->flusher_queue);
3985	flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
3986	}
3987	} else {
3988	/*
3989	* Oops, color space is full, wait on overflow queue.
3990	* The next flush completion will assign us
3991	* flush_color and transfer to flusher_queue.
3992	*/
3993	list_add_tail(&this_flusher.list, &wq->flusher_overflow);
3994	}
3995
3996	check_flush_dependency(wq, NULL, false);
3997
3998	mutex_unlock(&wq->mutex);
3999
4000	wait_for_completion(&this_flusher.done);
4001
4002	/*
4003	* Wake-up-and-cascade phase
4004	*
4005	* First flushers are responsible for cascading flushes and
4006	* handling overflow. Non-first flushers can simply return.
4007	*/
4008	if (READ_ONCE(wq->first_flusher) != &this_flusher)
4009	return;
4010
4011	mutex_lock(&wq->mutex);
4012
4013	/* we might have raced, check again with mutex held */
4014	if (wq->first_flusher != &this_flusher)
4015	goto out_unlock;
4016
4017	WRITE_ONCE(wq->first_flusher, NULL);
4018
4019	WARN_ON_ONCE(!list_empty(&this_flusher.list));
4020	WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
4021
4022	while (true) {
4023	struct wq_flusher next, tmp;
4024
4025	/* complete all the flushers sharing the current flush color */
4026	list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
4027	if (next->flush_color != wq->flush_color)
4028	break;
4029	list_del_init(&next->list);
4030	complete(&next->done);
4031	}
4032
4033	WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) &&
4034	wq->flush_color != work_next_color(wq->work_color));
4035
4036	/* this flush_color is finished, advance by one */
4037	wq->flush_color = work_next_color(wq->flush_color);
4038
4039	/* one color has been freed, handle overflow queue */
4040	if (!list_empty(&wq->flusher_overflow)) {
4041	/*
4042	* Assign the same color to all overflowed
4043	* flushers, advance work_color and append to
4044	* flusher_queue. This is the start-to-wait
4045	* phase for these overflowed flushers.
4046	*/
4047	list_for_each_entry(tmp, &wq->flusher_overflow, list)
4048	tmp->flush_color = wq->work_color;
4049
4050	wq->work_color = work_next_color(wq->work_color);
4051
4052	list_splice_tail_init(&wq->flusher_overflow,
4053	&wq->flusher_queue);
4054	flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
4055	}
4056
4057	if (list_empty(&wq->flusher_queue)) {
4058	WARN_ON_ONCE(wq->flush_color != wq->work_color);
4059	break;
4060	}
4061
4062	/*
4063	* Need to flush more colors. Make the next flusher
4064	* the new first flusher and arm pwqs.
4065	*/
4066	WARN_ON_ONCE(wq->flush_color == wq->work_color);
4067	WARN_ON_ONCE(wq->flush_color != next->flush_color);
4068
4069	list_del_init(&next->list);
4070	wq->first_flusher = next;
4071
4072	if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1))
4073	break;
4074
4075	/*
4076	* Meh... this color is already done, clear first
4077	* flusher and repeat cascading.
4078	*/
4079	wq->first_flusher = NULL;
4080	}
4081
4082	out_unlock:
4083	mutex_unlock(&wq->mutex);
4084	}
4085	EXPORT_SYMBOL(__flush_workqueue);
4086
4087	/**
4088	* drain_workqueue - drain a workqueue
4089	* @wq: workqueue to drain
4090	*
4091	* Wait until the workqueue becomes empty. While draining is in progress,
4092	* only chain queueing is allowed. IOW, only currently pending or running
4093	* work items on @wq can queue further work items on it. @wq is flushed
4094	* repeatedly until it becomes empty. The number of flushing is determined
4095	* by the depth of chaining and should be relatively short. Whine if it
4096	* takes too long.
4097	*/
4098	void drain_workqueue(struct workqueue_struct *wq)
4099	{
4100	unsigned int flush_cnt = 0;
4101	struct pool_workqueue *pwq;
4102
4103	/*
4104	* __queue_work() needs to test whether there are drainers, is much
4105	* hotter than drain_workqueue() and already looks at @wq->flags.
4106	* Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
4107	*/
4108	mutex_lock(&wq->mutex);
4109	if (!wq->nr_drainers++)
4110	wq->flags \|= __WQ_DRAINING;
4111	mutex_unlock(&wq->mutex);
4112	reflush:
4113	__flush_workqueue(wq);
4114
4115	mutex_lock(&wq->mutex);
4116
4117	for_each_pwq(pwq, wq) {
4118	bool drained;
4119
4120	raw_spin_lock_irq(&pwq->pool->lock);
4121	drained = pwq_is_empty(pwq);
4122	raw_spin_unlock_irq(&pwq->pool->lock);
4123
4124	if (drained)
4125	continue;
4126
4127	if (++flush_cnt == 10 \|\|
4128	(flush_cnt % 100 == 0 && flush_cnt <= 1000))
4129	pr_warn("workqueue %s: %s() isn't complete after %u tries\n",
4130	wq->name, __func__, flush_cnt);
4131
4132	mutex_unlock(&wq->mutex);
4133	goto reflush;
4134	}
4135
4136	if (!--wq->nr_drainers)
4137	wq->flags &= ~__WQ_DRAINING;
4138	mutex_unlock(&wq->mutex);
4139	}
4140	EXPORT_SYMBOL_GPL(drain_workqueue);
4141
4142	static bool start_flush_work(struct work_struct work, struct wq_barrier barr,
4143	bool from_cancel)
4144	{
4145	struct worker *worker = NULL;
4146	struct worker_pool *pool;
4147	struct pool_workqueue *pwq;
4148	struct workqueue_struct *wq;
4149
4150	rcu_read_lock();
4151	pool = get_work_pool(work);
4152	if (!pool) {
4153	rcu_read_unlock();
4154	return false;
4155	}
4156
4157	raw_spin_lock_irq(&pool->lock);
4158	/* see the comment in try_to_grab_pending() with the same code */
4159	pwq = get_work_pwq(work);
4160	if (pwq) {
4161	if (unlikely(pwq->pool != pool))
4162	goto already_gone;
4163	} else {
4164	worker = find_worker_executing_work(pool, work);
4165	if (!worker)
4166	goto already_gone;
4167	pwq = worker->current_pwq;
4168	}
4169
4170	wq = pwq->wq;
4171	check_flush_dependency(wq, work, from_cancel);
4172
4173	insert_wq_barrier(pwq, barr, work, worker);
4174	raw_spin_unlock_irq(&pool->lock);
4175
4176	touch_work_lockdep_map(work, wq);
4177
4178	/*
4179	* Force a lock recursion deadlock when using flush_work() inside a
4180	* single-threaded or rescuer equipped workqueue.
4181	*
4182	* For single threaded workqueues the deadlock happens when the work
4183	* is after the work issuing the flush_work(). For rescuer equipped
4184	* workqueues the deadlock happens when the rescuer stalls, blocking
4185	* forward progress.
4186	*/
4187	if (!from_cancel && (wq->saved_max_active == 1 \|\| wq->rescuer))
4188	touch_wq_lockdep_map(wq);
4189
4190	rcu_read_unlock();
4191	return true;
4192	already_gone:
4193	raw_spin_unlock_irq(&pool->lock);
4194	rcu_read_unlock();
4195	return false;
4196	}
4197
4198	static bool __flush_work(struct work_struct *work, bool from_cancel)
4199	{
4200	struct wq_barrier barr;
4201
4202	if (WARN_ON(!wq_online))
4203	return false;
4204
4205	if (WARN_ON(!work->func))
4206	return false;
4207
4208	if (!start_flush_work(work, &barr, from_cancel))
4209	return false;
4210
4211	/*
4212	* start_flush_work() returned %true. If @from_cancel is set, we know
4213	* that @work must have been executing during start_flush_work() and
4214	* can't currently be queued. Its data must contain OFFQ bits. If @work
4215	* was queued on a BH workqueue, we also know that it was running in the
4216	* BH context and thus can be busy-waited.
4217	*/
4218	if (from_cancel) {
4219	unsigned long data = *work_data_bits(work);
4220
4221	if (!WARN_ON_ONCE(data & WORK_STRUCT_PWQ) &&
4222	(data & WORK_OFFQ_BH)) {
4223	/*
4224	* On RT, prevent a live lock when %current preempted
4225	* soft interrupt processing or prevents ksoftirqd from
4226	* running by keeping flipping BH. If the BH work item
4227	* runs on a different CPU then this has no effect other
4228	* than doing the BH disable/enable dance for nothing.
4229	* This is copied from
4230	* kernel/softirq.c::tasklet_unlock_spin_wait().
4231	*/
4232	while (!try_wait_for_completion(&barr.done)) {
4233	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
4234	local_bh_disable();
4235	local_bh_enable();
4236	} else {
4237	cpu_relax();
4238	}
4239	}
4240	goto out_destroy;
4241	}
4242	}
4243
4244	wait_for_completion(&barr.done);
4245
4246	out_destroy:
4247	destroy_work_on_stack(&barr.work);
4248	return true;
4249	}
4250
4251	/**
4252	* flush_work - wait for a work to finish executing the last queueing instance
4253	* @work: the work to flush
4254	*
4255	* Wait until @work has finished execution. @work is guaranteed to be idle
4256	* on return if it hasn't been requeued since flush started.
4257	*
4258	* Return:
4259	* %true if flush_work() waited for the work to finish execution,
4260	* %false if it was already idle.
4261	*/
4262	bool flush_work(struct work_struct *work)
4263	{
4264	might_sleep();
4265	return __flush_work(work, false);
4266	}
4267	EXPORT_SYMBOL_GPL(flush_work);
4268
4269	/**
4270	* flush_delayed_work - wait for a dwork to finish executing the last queueing
4271	* @dwork: the delayed work to flush
4272	*
4273	* Delayed timer is cancelled and the pending work is queued for
4274	* immediate execution. Like flush_work(), this function only
4275	* considers the last queueing instance of @dwork.
4276	*
4277	* Return:
4278	* %true if flush_work() waited for the work to finish execution,
4279	* %false if it was already idle.
4280	*/
4281	bool flush_delayed_work(struct delayed_work *dwork)
4282	{
4283	local_irq_disable();
4284	if (timer_delete_sync(&dwork->timer))
4285	__queue_work(dwork->cpu, dwork->wq, &dwork->work);
4286	local_irq_enable();
4287	return flush_work(&dwork->work);
4288	}
4289	EXPORT_SYMBOL(flush_delayed_work);
4290
4291	/**
4292	* flush_rcu_work - wait for a rwork to finish executing the last queueing
4293	* @rwork: the rcu work to flush
4294	*
4295	* Return:
4296	* %true if flush_rcu_work() waited for the work to finish execution,
4297	* %false if it was already idle.
4298	*/
4299	bool flush_rcu_work(struct rcu_work *rwork)
4300	{
4301	if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) {
4302	rcu_barrier();
4303	flush_work(&rwork->work);
4304	return true;
4305	} else {
4306	return flush_work(&rwork->work);
4307	}
4308	}
4309	EXPORT_SYMBOL(flush_rcu_work);
4310
4311	static void work_offqd_disable(struct work_offq_data *offqd)
4312	{
4313	const unsigned long max = (1lu << WORK_OFFQ_DISABLE_BITS) - 1;
4314
4315	if (likely(offqd->disable < max))
4316	offqd->disable++;
4317	else
4318	WARN_ONCE(true, "workqueue: work disable count overflowed\n");
4319	}
4320
4321	static void work_offqd_enable(struct work_offq_data *offqd)
4322	{
4323	if (likely(offqd->disable > 0))
4324	offqd->disable--;
4325	else
4326	WARN_ONCE(true, "workqueue: work disable count underflowed\n");
4327	}
4328
4329	static bool __cancel_work(struct work_struct *work, u32 cflags)
4330	{
4331	struct work_offq_data offqd;
4332	unsigned long irq_flags;
4333	int ret;
4334
4335	ret = work_grab_pending(work, cflags, &irq_flags);
4336
4337	work_offqd_unpack(&offqd, *work_data_bits(work));
4338
4339	if (cflags & WORK_CANCEL_DISABLE)
4340	work_offqd_disable(&offqd);
4341
4342	set_work_pool_and_clear_pending(work, offqd.pool_id,
4343	work_offqd_pack_flags(&offqd));
4344	local_irq_restore(irq_flags);
4345	return ret;
4346	}
4347
4348	static bool __cancel_work_sync(struct work_struct *work, u32 cflags)
4349	{
4350	bool ret;
4351
4352	ret = __cancel_work(work, cflags \| WORK_CANCEL_DISABLE);
4353
4354	if (*work_data_bits(work) & WORK_OFFQ_BH)
4355	WARN_ON_ONCE(in_hardirq());
4356	else
4357	might_sleep();
4358
4359	/*
4360	* Skip __flush_work() during early boot when we know that @work isn't
4361	* executing. This allows canceling during early boot.
4362	*/
4363	if (wq_online)
4364	__flush_work(work, true);
4365
4366	if (!(cflags & WORK_CANCEL_DISABLE))
4367	enable_work(work);
4368
4369	return ret;
4370	}
4371
4372	/*
4373	* See cancel_delayed_work()
4374	*/
4375	bool cancel_work(struct work_struct *work)
4376	{
4377	return __cancel_work(work, 0);
4378	}
4379	EXPORT_SYMBOL(cancel_work);
4380
4381	/**
4382	* cancel_work_sync - cancel a work and wait for it to finish
4383	* @work: the work to cancel
4384	*
4385	* Cancel @work and wait for its execution to finish. This function can be used
4386	* even if the work re-queues itself or migrates to another workqueue. On return
4387	* from this function, @work is guaranteed to be not pending or executing on any
4388	* CPU as long as there aren't racing enqueues.
4389	*
4390	* cancel_work_sync(&delayed_work->work) must not be used for delayed_work's.
4391	* Use cancel_delayed_work_sync() instead.
4392	*
4393	* Must be called from a sleepable context if @work was last queued on a non-BH
4394	* workqueue. Can also be called from non-hardirq atomic contexts including BH
4395	* if @work was last queued on a BH workqueue.
4396	*
4397	* Returns %true if @work was pending, %false otherwise.
4398	*/
4399	bool cancel_work_sync(struct work_struct *work)
4400	{
4401	return __cancel_work_sync(work, 0);
4402	}
4403	EXPORT_SYMBOL_GPL(cancel_work_sync);
4404
4405	/**
4406	* cancel_delayed_work - cancel a delayed work
4407	* @dwork: delayed_work to cancel
4408	*
4409	* Kill off a pending delayed_work.
4410	*
4411	* Return: %true if @dwork was pending and canceled; %false if it wasn't
4412	* pending.
4413	*
4414	* Note:
4415	* The work callback function may still be running on return, unless
4416	* it returns %true and the work doesn't re-arm itself. Explicitly flush or
4417	* use cancel_delayed_work_sync() to wait on it.
4418	*
4419	* This function is safe to call from any context including IRQ handler.
4420	*/
4421	bool cancel_delayed_work(struct delayed_work *dwork)
4422	{
4423	return __cancel_work(&dwork->work, WORK_CANCEL_DELAYED);
4424	}
4425	EXPORT_SYMBOL(cancel_delayed_work);
4426
4427	/**
4428	* cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
4429	* @dwork: the delayed work cancel
4430	*
4431	* This is cancel_work_sync() for delayed works.
4432	*
4433	* Return:
4434	* %true if @dwork was pending, %false otherwise.
4435	*/
4436	bool cancel_delayed_work_sync(struct delayed_work *dwork)
4437	{
4438	return __cancel_work_sync(&dwork->work, WORK_CANCEL_DELAYED);
4439	}
4440	EXPORT_SYMBOL(cancel_delayed_work_sync);
4441
4442	/**
4443	* disable_work - Disable and cancel a work item
4444	* @work: work item to disable
4445	*
4446	* Disable @work by incrementing its disable count and cancel it if currently
4447	* pending. As long as the disable count is non-zero, any attempt to queue @work
4448	* will fail and return %false. The maximum supported disable depth is 2 to the
4449	* power of %WORK_OFFQ_DISABLE_BITS, currently 65536.
4450	*
4451	* Can be called from any context. Returns %true if @work was pending, %false
4452	* otherwise.
4453	*/
4454	bool disable_work(struct work_struct *work)
4455	{
4456	return __cancel_work(work, WORK_CANCEL_DISABLE);
4457	}
4458	EXPORT_SYMBOL_GPL(disable_work);
4459
4460	/**
4461	* disable_work_sync - Disable, cancel and drain a work item
4462	* @work: work item to disable
4463	*
4464	* Similar to disable_work() but also wait for @work to finish if currently
4465	* executing.
4466	*
4467	* Must be called from a sleepable context if @work was last queued on a non-BH
4468	* workqueue. Can also be called from non-hardirq atomic contexts including BH
4469	* if @work was last queued on a BH workqueue.
4470	*
4471	* Returns %true if @work was pending, %false otherwise.
4472	*/
4473	bool disable_work_sync(struct work_struct *work)
4474	{
4475	return __cancel_work_sync(work, WORK_CANCEL_DISABLE);
4476	}
4477	EXPORT_SYMBOL_GPL(disable_work_sync);
4478
4479	/**
4480	* enable_work - Enable a work item
4481	* @work: work item to enable
4482	*
4483	* Undo disable_work[_sync]() by decrementing @work's disable count. @work can
4484	* only be queued if its disable count is 0.
4485	*
4486	* Can be called from any context. Returns %true if the disable count reached 0.
4487	* Otherwise, %false.
4488	*/
4489	bool enable_work(struct work_struct *work)
4490	{
4491	struct work_offq_data offqd;
4492	unsigned long irq_flags;
4493
4494	work_grab_pending(work, 0, &irq_flags);
4495
4496	work_offqd_unpack(&offqd, *work_data_bits(work));
4497	work_offqd_enable(&offqd);
4498	set_work_pool_and_clear_pending(work, offqd.pool_id,
4499	work_offqd_pack_flags(&offqd));
4500	local_irq_restore(irq_flags);
4501
4502	return !offqd.disable;
4503	}
4504	EXPORT_SYMBOL_GPL(enable_work);
4505
4506	/**
4507	* disable_delayed_work - Disable and cancel a delayed work item
4508	* @dwork: delayed work item to disable
4509	*
4510	* disable_work() for delayed work items.
4511	*/
4512	bool disable_delayed_work(struct delayed_work *dwork)
4513	{
4514	return __cancel_work(&dwork->work,
4515	WORK_CANCEL_DELAYED \| WORK_CANCEL_DISABLE);
4516	}
4517	EXPORT_SYMBOL_GPL(disable_delayed_work);
4518
4519	/**
4520	* disable_delayed_work_sync - Disable, cancel and drain a delayed work item
4521	* @dwork: delayed work item to disable
4522	*
4523	* disable_work_sync() for delayed work items.
4524	*/
4525	bool disable_delayed_work_sync(struct delayed_work *dwork)
4526	{
4527	return __cancel_work_sync(&dwork->work,
4528	WORK_CANCEL_DELAYED \| WORK_CANCEL_DISABLE);
4529	}
4530	EXPORT_SYMBOL_GPL(disable_delayed_work_sync);
4531
4532	/**
4533	* enable_delayed_work - Enable a delayed work item
4534	* @dwork: delayed work item to enable
4535	*
4536	* enable_work() for delayed work items.
4537	*/
4538	bool enable_delayed_work(struct delayed_work *dwork)
4539	{
4540	return enable_work(&dwork->work);
4541	}
4542	EXPORT_SYMBOL_GPL(enable_delayed_work);
4543
4544	/**
4545	* schedule_on_each_cpu - execute a function synchronously on each online CPU
4546	* @func: the function to call
4547	*
4548	* schedule_on_each_cpu() executes @func on each online CPU using the
4549	* system workqueue and blocks until all CPUs have completed.
4550	* schedule_on_each_cpu() is very slow.
4551	*
4552	* Return:
4553	* 0 on success, -errno on failure.
4554	*/
4555	int schedule_on_each_cpu(work_func_t func)
4556	{
4557	int cpu;
4558	struct work_struct __percpu *works;
4559
4560	works = alloc_percpu(struct work_struct);
4561	if (!works)
4562	return -ENOMEM;
4563
4564	cpus_read_lock();
4565
4566	for_each_online_cpu(cpu) {
4567	struct work_struct *work = per_cpu_ptr(works, cpu);
4568
4569	INIT_WORK(work, func);
4570	schedule_work_on(cpu, work);
4571	}
4572
4573	for_each_online_cpu(cpu)
4574	flush_work(per_cpu_ptr(works, cpu));
4575
4576	cpus_read_unlock();
4577	free_percpu(works);
4578	return 0;
4579	}
4580
4581	/**
4582	* execute_in_process_context - reliably execute the routine with user context
4583	* @fn: the function to execute
4584	* @ew: guaranteed storage for the execute work structure (must
4585	* be available when the work executes)
4586	*
4587	* Executes the function immediately if process context is available,
4588	* otherwise schedules the function for delayed execution.
4589	*
4590	* Return: 0 - function was executed
4591	* 1 - function was scheduled for execution
4592	*/
4593	int execute_in_process_context(work_func_t fn, struct execute_work *ew)
4594	{
4595	if (!in_interrupt()) {
4596	fn(&ew->work);
4597	return 0;
4598	}
4599
4600	INIT_WORK(&ew->work, fn);
4601	schedule_work(&ew->work);
4602
4603	return 1;
4604	}
4605	EXPORT_SYMBOL_GPL(execute_in_process_context);
4606
4607	/**
4608	* free_workqueue_attrs - free a workqueue_attrs
4609	* @attrs: workqueue_attrs to free
4610	*
4611	* Undo alloc_workqueue_attrs().
4612	*/
4613	void free_workqueue_attrs(struct workqueue_attrs *attrs)
4614	{
4615	if (attrs) {
4616	free_cpumask_var(attrs->cpumask);
4617	free_cpumask_var(attrs->__pod_cpumask);
4618	kfree(attrs);
4619	}
4620	}
4621
4622	/**
4623	* alloc_workqueue_attrs - allocate a workqueue_attrs
4624	*
4625	* Allocate a new workqueue_attrs, initialize with default settings and
4626	* return it.
4627	*
4628	* Return: The allocated new workqueue_attr on success. %NULL on failure.
4629	*/
4630	struct workqueue_attrs *alloc_workqueue_attrs(void)
4631	{
4632	struct workqueue_attrs *attrs;
4633
4634	attrs = kzalloc(sizeof(*attrs), GFP_KERNEL);
4635	if (!attrs)
4636	goto fail;
4637	if (!alloc_cpumask_var(&attrs->cpumask, GFP_KERNEL))
4638	goto fail;
4639	if (!alloc_cpumask_var(&attrs->__pod_cpumask, GFP_KERNEL))
4640	goto fail;
4641
4642	cpumask_copy(attrs->cpumask, cpu_possible_mask);
4643	attrs->affn_scope = WQ_AFFN_DFL;
4644	return attrs;
4645	fail:
4646	free_workqueue_attrs(attrs);
4647	return NULL;
4648	}
4649
4650	static void copy_workqueue_attrs(struct workqueue_attrs *to,
4651	const struct workqueue_attrs *from)
4652	{
4653	to->nice = from->nice;
4654	cpumask_copy(to->cpumask, from->cpumask);
4655	cpumask_copy(to->__pod_cpumask, from->__pod_cpumask);
4656	to->affn_strict = from->affn_strict;
4657
4658	/*
4659	* Unlike hash and equality test, copying shouldn't ignore wq-only
4660	* fields as copying is used for both pool and wq attrs. Instead,
4661	* get_unbound_pool() explicitly clears the fields.
4662	*/
4663	to->affn_scope = from->affn_scope;
4664	to->ordered = from->ordered;
4665	}
4666
4667	/*
4668	* Some attrs fields are workqueue-only. Clear them for worker_pool's. See the
4669	* comments in 'struct workqueue_attrs' definition.
4670	*/
4671	static void wqattrs_clear_for_pool(struct workqueue_attrs *attrs)
4672	{
4673	attrs->affn_scope = WQ_AFFN_NR_TYPES;
4674	attrs->ordered = false;
4675	if (attrs->affn_strict)
4676	cpumask_copy(attrs->cpumask, cpu_possible_mask);
4677	}
4678
4679	/* hash value of the content of @attr */
4680	static u32 wqattrs_hash(const struct workqueue_attrs *attrs)
4681	{
4682	u32 hash = 0;
4683
4684	hash = jhash_1word(attrs->nice, hash);
4685	hash = jhash_1word(attrs->affn_strict, hash);
4686	hash = jhash(cpumask_bits(attrs->__pod_cpumask),
4687	BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
4688	if (!attrs->affn_strict)
4689	hash = jhash(cpumask_bits(attrs->cpumask),
4690	BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
4691	return hash;
4692	}
4693
4694	/* content equality test */
4695	static bool wqattrs_equal(const struct workqueue_attrs *a,
4696	const struct workqueue_attrs *b)
4697	{
4698	if (a->nice != b->nice)
4699	return false;
4700	if (a->affn_strict != b->affn_strict)
4701	return false;
4702	if (!cpumask_equal(a->__pod_cpumask, b->__pod_cpumask))
4703	return false;
4704	if (!a->affn_strict && !cpumask_equal(a->cpumask, b->cpumask))
4705	return false;
4706	return true;
4707	}
4708
4709	/* Update @attrs with actually available CPUs */
4710	static void wqattrs_actualize_cpumask(struct workqueue_attrs *attrs,
4711	const cpumask_t *unbound_cpumask)
4712	{
4713	/*
4714	* Calculate the effective CPU mask of @attrs given @unbound_cpumask. If
4715	* @attrs->cpumask doesn't overlap with @unbound_cpumask, we fallback to
4716	* @unbound_cpumask.
4717	*/
4718	cpumask_and(attrs->cpumask, attrs->cpumask, unbound_cpumask);
4719	if (unlikely(cpumask_empty(attrs->cpumask)))
4720	cpumask_copy(attrs->cpumask, unbound_cpumask);
4721	}
4722
4723	/* find wq_pod_type to use for @attrs */
4724	static const struct wq_pod_type *
4725	wqattrs_pod_type(const struct workqueue_attrs *attrs)
4726	{
4727	enum wq_affn_scope scope;
4728	struct wq_pod_type *pt;
4729
4730	/* to synchronize access to wq_affn_dfl */
4731	lockdep_assert_held(&wq_pool_mutex);
4732
4733	if (attrs->affn_scope == WQ_AFFN_DFL)
4734	scope = wq_affn_dfl;
4735	else
4736	scope = attrs->affn_scope;
4737
4738	pt = &wq_pod_types[scope];
4739
4740	if (!WARN_ON_ONCE(attrs->affn_scope == WQ_AFFN_NR_TYPES) &&
4741	likely(pt->nr_pods))
4742	return pt;
4743
4744	/*
4745	* Before workqueue_init_topology(), only SYSTEM is available which is
4746	* initialized in workqueue_init_early().
4747	*/
4748	pt = &wq_pod_types[WQ_AFFN_SYSTEM];
4749	BUG_ON(!pt->nr_pods);
4750	return pt;
4751	}
4752
4753	/**
4754	* init_worker_pool - initialize a newly zalloc'd worker_pool
4755	* @pool: worker_pool to initialize
4756	*
4757	* Initialize a newly zalloc'd @pool. It also allocates @pool->attrs.
4758	*
4759	* Return: 0 on success, -errno on failure. Even on failure, all fields
4760	* inside @pool proper are initialized and put_unbound_pool() can be called
4761	* on @pool safely to release it.
4762	*/
4763	static int init_worker_pool(struct worker_pool *pool)
4764	{
4765	raw_spin_lock_init(&pool->lock);
4766	pool->id = -1;
4767	pool->cpu = -1;
4768	pool->node = NUMA_NO_NODE;
4769	pool->flags \|= POOL_DISASSOCIATED;
4770	pool->watchdog_ts = jiffies;
4771	INIT_LIST_HEAD(&pool->worklist);
4772	INIT_LIST_HEAD(&pool->idle_list);
4773	hash_init(pool->busy_hash);
4774
4775	timer_setup(&pool->idle_timer, idle_worker_timeout, TIMER_DEFERRABLE);
4776	INIT_WORK(&pool->idle_cull_work, idle_cull_fn);
4777
4778	timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0);
4779
4780	INIT_LIST_HEAD(&pool->workers);
4781
4782	ida_init(&pool->worker_ida);
4783	INIT_HLIST_NODE(&pool->hash_node);
4784	pool->refcnt = 1;
4785
4786	/* shouldn't fail above this point */
4787	pool->attrs = alloc_workqueue_attrs();
4788	if (!pool->attrs)
4789	return -ENOMEM;
4790
4791	wqattrs_clear_for_pool(pool->attrs);
4792
4793	return 0;
4794	}
4795
4796	#ifdef CONFIG_LOCKDEP
4797	static void wq_init_lockdep(struct workqueue_struct *wq)
4798	{
4799	char *lock_name;
4800
4801	lockdep_register_key(&wq->key);
4802	lock_name = kasprintf(GFP_KERNEL, "%s%s", "(wq_completion)", wq->name);
4803	if (!lock_name)
4804	lock_name = wq->name;
4805
4806	wq->lock_name = lock_name;
4807	wq->lockdep_map = &wq->__lockdep_map;
4808	lockdep_init_map(wq->lockdep_map, lock_name, &wq->key, 0);
4809	}
4810
4811	static void wq_unregister_lockdep(struct workqueue_struct *wq)
4812	{
4813	if (wq->lockdep_map != &wq->__lockdep_map)
4814	return;
4815
4816	lockdep_unregister_key(&wq->key);
4817	}
4818
4819	static void wq_free_lockdep(struct workqueue_struct *wq)
4820	{
4821	if (wq->lockdep_map != &wq->__lockdep_map)
4822	return;
4823
4824	if (wq->lock_name != wq->name)
4825	kfree(wq->lock_name);
4826	}
4827	#else
4828	static void wq_init_lockdep(struct workqueue_struct *wq)
4829	{
4830	}
4831
4832	static void wq_unregister_lockdep(struct workqueue_struct *wq)
4833	{
4834	}
4835
4836	static void wq_free_lockdep(struct workqueue_struct *wq)
4837	{
4838	}
4839	#endif
4840
4841	static void free_node_nr_active(struct wq_node_nr_active **nna_ar)
4842	{
4843	int node;
4844
4845	for_each_node(node) {
4846	kfree(nna_ar[node]);
4847	nna_ar[node] = NULL;
4848	}
4849
4850	kfree(nna_ar[nr_node_ids]);
4851	nna_ar[nr_node_ids] = NULL;
4852	}
4853
4854	static void init_node_nr_active(struct wq_node_nr_active *nna)
4855	{
4856	nna->max = WQ_DFL_MIN_ACTIVE;
4857	atomic_set(&nna->nr, 0);
4858	raw_spin_lock_init(&nna->lock);
4859	INIT_LIST_HEAD(&nna->pending_pwqs);
4860	}
4861
4862	/*
4863	* Each node's nr_active counter will be accessed mostly from its own node and
4864	* should be allocated in the node.
4865	*/
4866	static int alloc_node_nr_active(struct wq_node_nr_active **nna_ar)
4867	{
4868	struct wq_node_nr_active *nna;
4869	int node;
4870
4871	for_each_node(node) {
4872	nna = kzalloc_node(sizeof(*nna), GFP_KERNEL, node);
4873	if (!nna)
4874	goto err_free;
4875	init_node_nr_active(nna);
4876	nna_ar[node] = nna;
4877	}
4878
4879	/* [nr_node_ids] is used as the fallback */
4880	nna = kzalloc_node(sizeof(*nna), GFP_KERNEL, NUMA_NO_NODE);
4881	if (!nna)
4882	goto err_free;
4883	init_node_nr_active(nna);
4884	nna_ar[nr_node_ids] = nna;
4885
4886	return 0;
4887
4888	err_free:
4889	free_node_nr_active(nna_ar);
4890	return -ENOMEM;
4891	}
4892
4893	static void rcu_free_wq(struct rcu_head *rcu)
4894	{
4895	struct workqueue_struct *wq =
4896	container_of(rcu, struct workqueue_struct, rcu);
4897
4898	if (wq->flags & WQ_UNBOUND)
4899	free_node_nr_active(wq->node_nr_active);
4900
4901	wq_free_lockdep(wq);
4902	free_percpu(wq->cpu_pwq);
4903	free_workqueue_attrs(wq->unbound_attrs);
4904	kfree(wq);
4905	}
4906
4907	static void rcu_free_pool(struct rcu_head *rcu)
4908	{
4909	struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu);
4910
4911	ida_destroy(&pool->worker_ida);
4912	free_workqueue_attrs(pool->attrs);
4913	kfree(pool);
4914	}
4915
4916	/**
4917	* put_unbound_pool - put a worker_pool
4918	* @pool: worker_pool to put
4919	*
4920	* Put @pool. If its refcnt reaches zero, it gets destroyed in RCU
4921	* safe manner. get_unbound_pool() calls this function on its failure path
4922	* and this function should be able to release pools which went through,
4923	* successfully or not, init_worker_pool().
4924	*
4925	* Should be called with wq_pool_mutex held.
4926	*/
4927	static void put_unbound_pool(struct worker_pool *pool)
4928	{
4929	struct worker *worker;
4930	LIST_HEAD(cull_list);
4931
4932	lockdep_assert_held(&wq_pool_mutex);
4933
4934	if (--pool->refcnt)
4935	return;
4936
4937	/* sanity checks */
4938	if (WARN_ON(!(pool->cpu < 0)) \|\|
4939	WARN_ON(!list_empty(&pool->worklist)))
4940	return;
4941
4942	/* release id and unhash */
4943	if (pool->id >= 0)
4944	idr_remove(&worker_pool_idr, pool->id);
4945	hash_del(&pool->hash_node);
4946
4947	/*
4948	* Become the manager and destroy all workers. This prevents
4949	* @pool's workers from blocking on attach_mutex. We're the last
4950	* manager and @pool gets freed with the flag set.
4951	*
4952	* Having a concurrent manager is quite unlikely to happen as we can
4953	* only get here with
4954	* pwq->refcnt == pool->refcnt == 0
4955	* which implies no work queued to the pool, which implies no worker can
4956	* become the manager. However a worker could have taken the role of
4957	* manager before the refcnts dropped to 0, since maybe_create_worker()
4958	* drops pool->lock
4959	*/
4960	while (true) {
4961	rcuwait_wait_event(&manager_wait,
4962	!(pool->flags & POOL_MANAGER_ACTIVE),
4963	TASK_UNINTERRUPTIBLE);
4964
4965	mutex_lock(&wq_pool_attach_mutex);
4966	raw_spin_lock_irq(&pool->lock);
4967	if (!(pool->flags & POOL_MANAGER_ACTIVE)) {
4968	pool->flags \|= POOL_MANAGER_ACTIVE;
4969	break;
4970	}
4971	raw_spin_unlock_irq(&pool->lock);
4972	mutex_unlock(&wq_pool_attach_mutex);
4973	}
4974
4975	while ((worker = first_idle_worker(pool)))
4976	set_worker_dying(worker, &cull_list);
4977	WARN_ON(pool->nr_workers \|\| pool->nr_idle);
4978	raw_spin_unlock_irq(&pool->lock);
4979
4980	detach_dying_workers(&cull_list);
4981
4982	mutex_unlock(&wq_pool_attach_mutex);
4983
4984	reap_dying_workers(&cull_list);
4985
4986	/* shut down the timers */
4987	timer_delete_sync(&pool->idle_timer);
4988	cancel_work_sync(&pool->idle_cull_work);
4989	timer_delete_sync(&pool->mayday_timer);
4990
4991	/* RCU protected to allow dereferences from get_work_pool() */
4992	call_rcu(&pool->rcu, rcu_free_pool);
4993	}
4994
4995	/**
4996	* get_unbound_pool - get a worker_pool with the specified attributes
4997	* @attrs: the attributes of the worker_pool to get
4998	*
4999	* Obtain a worker_pool which has the same attributes as @attrs, bump the
5000	* reference count and return it. If there already is a matching
5001	* worker_pool, it will be used; otherwise, this function attempts to
5002	* create a new one.
5003	*
5004	* Should be called with wq_pool_mutex held.
5005	*
5006	* Return: On success, a worker_pool with the same attributes as @attrs.
5007	* On failure, %NULL.
5008	*/
5009	static struct worker_pool get_unbound_pool(const struct workqueue_attrs attrs)
5010	{
5011	struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_NUMA];
5012	u32 hash = wqattrs_hash(attrs);
5013	struct worker_pool *pool;
5014	int pod, node = NUMA_NO_NODE;
5015
5016	lockdep_assert_held(&wq_pool_mutex);
5017
5018	/* do we already have a matching pool? */
5019	hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) {
5020	if (wqattrs_equal(pool->attrs, attrs)) {
5021	pool->refcnt++;
5022	return pool;
5023	}
5024	}
5025
5026	/* If __pod_cpumask is contained inside a NUMA pod, that's our node */
5027	for (pod = 0; pod < pt->nr_pods; pod++) {
5028	if (cpumask_subset(attrs->__pod_cpumask, pt->pod_cpus[pod])) {
5029	node = pt->pod_node[pod];
5030	break;
5031	}
5032	}
5033
5034	/* nope, create a new one */
5035	pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, node);
5036	if (!pool \|\| init_worker_pool(pool) < 0)
5037	goto fail;
5038
5039	pool->node = node;
5040	copy_workqueue_attrs(pool->attrs, attrs);
5041	wqattrs_clear_for_pool(pool->attrs);
5042
5043	if (worker_pool_assign_id(pool) < 0)
5044	goto fail;
5045
5046	/* create and start the initial worker */
5047	if (wq_online && !create_worker(pool))
5048	goto fail;
5049
5050	/* install */
5051	hash_add(unbound_pool_hash, &pool->hash_node, hash);
5052
5053	return pool;
5054	fail:
5055	if (pool)
5056	put_unbound_pool(pool);
5057	return NULL;
5058	}
5059
5060	/*
5061	* Scheduled on pwq_release_worker by put_pwq() when an unbound pwq hits zero
5062	* refcnt and needs to be destroyed.
5063	*/
5064	static void pwq_release_workfn(struct kthread_work *work)
5065	{
5066	struct pool_workqueue *pwq = container_of(work, struct pool_workqueue,
5067	release_work);
5068	struct workqueue_struct *wq = pwq->wq;
5069	struct worker_pool *pool = pwq->pool;
5070	bool is_last = false;
5071
5072	/*
5073	* When @pwq is not linked, it doesn't hold any reference to the
5074	* @wq, and @wq is invalid to access.
5075	*/
5076	if (!list_empty(&pwq->pwqs_node)) {
5077	mutex_lock(&wq->mutex);
5078	list_del_rcu(&pwq->pwqs_node);
5079	is_last = list_empty(&wq->pwqs);
5080
5081	/*
5082	* For ordered workqueue with a plugged dfl_pwq, restart it now.
5083	*/
5084	if (!is_last && (wq->flags & __WQ_ORDERED))
5085	unplug_oldest_pwq(wq);
5086
5087	mutex_unlock(&wq->mutex);
5088	}
5089
5090	if (wq->flags & WQ_UNBOUND) {
5091	mutex_lock(&wq_pool_mutex);
5092	put_unbound_pool(pool);
5093	mutex_unlock(&wq_pool_mutex);
5094	}
5095
5096	if (!list_empty(&pwq->pending_node)) {
5097	struct wq_node_nr_active *nna =
5098	wq_node_nr_active(pwq->wq, pwq->pool->node);
5099
5100	raw_spin_lock_irq(&nna->lock);
5101	list_del_init(&pwq->pending_node);
5102	raw_spin_unlock_irq(&nna->lock);
5103	}
5104
5105	kfree_rcu(pwq, rcu);
5106
5107	/*
5108	* If we're the last pwq going away, @wq is already dead and no one
5109	* is gonna access it anymore. Schedule RCU free.
5110	*/
5111	if (is_last) {
5112	wq_unregister_lockdep(wq);
5113	call_rcu(&wq->rcu, rcu_free_wq);
5114	}
5115	}
5116
5117	/* initialize newly allocated @pwq which is associated with @wq and @pool */
5118	static void init_pwq(struct pool_workqueue pwq, struct workqueue_struct wq,
5119	struct worker_pool *pool)
5120	{
5121	BUG_ON((unsigned long)pwq & ~WORK_STRUCT_PWQ_MASK);
5122
5123	memset(pwq, 0, sizeof(*pwq));
5124
5125	pwq->pool = pool;
5126	pwq->wq = wq;
5127	pwq->flush_color = -1;
5128	pwq->refcnt = 1;
5129	INIT_LIST_HEAD(&pwq->inactive_works);
5130	INIT_LIST_HEAD(&pwq->pending_node);
5131	INIT_LIST_HEAD(&pwq->pwqs_node);
5132	INIT_LIST_HEAD(&pwq->mayday_node);
5133	kthread_init_work(&pwq->release_work, pwq_release_workfn);
5134	}
5135
5136	/* sync @pwq with the current state of its associated wq and link it */
5137	static void link_pwq(struct pool_workqueue *pwq)
5138	{
5139	struct workqueue_struct *wq = pwq->wq;
5140
5141	lockdep_assert_held(&wq->mutex);
5142
5143	/* may be called multiple times, ignore if already linked */
5144	if (!list_empty(&pwq->pwqs_node))
5145	return;
5146
5147	/* set the matching work_color */
5148	pwq->work_color = wq->work_color;
5149
5150	/* link in @pwq */
5151	list_add_tail_rcu(&pwq->pwqs_node, &wq->pwqs);
5152	}
5153
5154	/* obtain a pool matching @attr and create a pwq associating the pool and @wq */
5155	static struct pool_workqueue alloc_unbound_pwq(struct workqueue_struct wq,
5156	const struct workqueue_attrs *attrs)
5157	{
5158	struct worker_pool *pool;
5159	struct pool_workqueue *pwq;
5160
5161	lockdep_assert_held(&wq_pool_mutex);
5162
5163	pool = get_unbound_pool(attrs);
5164	if (!pool)
5165	return NULL;
5166
5167	pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node);
5168	if (!pwq) {
5169	put_unbound_pool(pool);
5170	return NULL;
5171	}
5172
5173	init_pwq(pwq, wq, pool);
5174	return pwq;
5175	}
5176
5177	static void apply_wqattrs_lock(void)
5178	{
5179	mutex_lock(&wq_pool_mutex);
5180	}
5181
5182	static void apply_wqattrs_unlock(void)
5183	{
5184	mutex_unlock(&wq_pool_mutex);
5185	}
5186
5187	/**
5188	* wq_calc_pod_cpumask - calculate a wq_attrs' cpumask for a pod
5189	* @attrs: the wq_attrs of the default pwq of the target workqueue
5190	* @cpu: the target CPU
5191	*
5192	* Calculate the cpumask a workqueue with @attrs should use on @pod.
5193	* The result is stored in @attrs->__pod_cpumask.
5194	*
5195	* If pod affinity is not enabled, @attrs->cpumask is always used. If enabled
5196	* and @pod has online CPUs requested by @attrs, the returned cpumask is the
5197	* intersection of the possible CPUs of @pod and @attrs->cpumask.
5198	*
5199	* The caller is responsible for ensuring that the cpumask of @pod stays stable.
5200	*/
5201	static void wq_calc_pod_cpumask(struct workqueue_attrs *attrs, int cpu)
5202	{
5203	const struct wq_pod_type *pt = wqattrs_pod_type(attrs);
5204	int pod = pt->cpu_pod[cpu];
5205
5206	/* calculate possible CPUs in @pod that @attrs wants */
5207	cpumask_and(attrs->__pod_cpumask, pt->pod_cpus[pod], attrs->cpumask);
5208	/* does @pod have any online CPUs @attrs wants? */
5209	if (!cpumask_intersects(attrs->__pod_cpumask, wq_online_cpumask)) {
5210	cpumask_copy(attrs->__pod_cpumask, attrs->cpumask);
5211	return;
5212	}
5213	}
5214
5215	/* install @pwq into @wq and return the old pwq, @cpu < 0 for dfl_pwq */
5216	static struct pool_workqueue install_unbound_pwq(struct workqueue_struct wq,
5217	int cpu, struct pool_workqueue *pwq)
5218	{
5219	struct pool_workqueue __rcu **slot = unbound_pwq_slot(wq, cpu);
5220	struct pool_workqueue *old_pwq;
5221
5222	lockdep_assert_held(&wq_pool_mutex);
5223	lockdep_assert_held(&wq->mutex);
5224
5225	/* link_pwq() can handle duplicate calls */
5226	link_pwq(pwq);
5227
5228	old_pwq = rcu_access_pointer(*slot);
5229	rcu_assign_pointer(*slot, pwq);
5230	return old_pwq;
5231	}
5232
5233	/* context to store the prepared attrs & pwqs before applying */
5234	struct apply_wqattrs_ctx {
5235	struct workqueue_struct wq; / target workqueue */
5236	struct workqueue_attrs attrs; / attrs to apply */
5237	struct list_head list; /* queued for batching commit */
5238	struct pool_workqueue *dfl_pwq;
5239	struct pool_workqueue *pwq_tbl[];
5240	};
5241
5242	/* free the resources after success or abort */
5243	static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx)
5244	{
5245	if (ctx) {
5246	int cpu;
5247
5248	for_each_possible_cpu(cpu)
5249	put_pwq_unlocked(ctx->pwq_tbl[cpu]);
5250	put_pwq_unlocked(ctx->dfl_pwq);
5251
5252	free_workqueue_attrs(ctx->attrs);
5253
5254	kfree(ctx);
5255	}
5256	}
5257
5258	/* allocate the attrs and pwqs for later installation */
5259	static struct apply_wqattrs_ctx *
5260	apply_wqattrs_prepare(struct workqueue_struct *wq,
5261	const struct workqueue_attrs *attrs,
5262	const cpumask_var_t unbound_cpumask)
5263	{
5264	struct apply_wqattrs_ctx *ctx;
5265	struct workqueue_attrs *new_attrs;
5266	int cpu;
5267
5268	lockdep_assert_held(&wq_pool_mutex);
5269
5270	if (WARN_ON(attrs->affn_scope < 0 \|\|
5271	attrs->affn_scope >= WQ_AFFN_NR_TYPES))
5272	return ERR_PTR(-EINVAL);
5273
5274	ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_cpu_ids), GFP_KERNEL);
5275
5276	new_attrs = alloc_workqueue_attrs();
5277	if (!ctx \|\| !new_attrs)
5278	goto out_free;
5279
5280	/*
5281	* If something goes wrong during CPU up/down, we'll fall back to
5282	* the default pwq covering whole @attrs->cpumask. Always create
5283	* it even if we don't use it immediately.
5284	*/
5285	copy_workqueue_attrs(new_attrs, attrs);
5286	wqattrs_actualize_cpumask(new_attrs, unbound_cpumask);
5287	cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask);
5288	ctx->dfl_pwq = alloc_unbound_pwq(wq, new_attrs);
5289	if (!ctx->dfl_pwq)
5290	goto out_free;
5291
5292	for_each_possible_cpu(cpu) {
5293	if (new_attrs->ordered) {
5294	ctx->dfl_pwq->refcnt++;
5295	ctx->pwq_tbl[cpu] = ctx->dfl_pwq;
5296	} else {
5297	wq_calc_pod_cpumask(new_attrs, cpu);
5298	ctx->pwq_tbl[cpu] = alloc_unbound_pwq(wq, new_attrs);
5299	if (!ctx->pwq_tbl[cpu])
5300	goto out_free;
5301	}
5302	}
5303
5304	/* save the user configured attrs and sanitize it. */
5305	copy_workqueue_attrs(new_attrs, attrs);
5306	cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);
5307	cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask);
5308	ctx->attrs = new_attrs;
5309
5310	/*
5311	* For initialized ordered workqueues, there should only be one pwq
5312	* (dfl_pwq). Set the plugged flag of ctx->dfl_pwq to suspend execution
5313	* of newly queued work items until execution of older work items in
5314	* the old pwq's have completed.
5315	*/
5316	if ((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs))
5317	ctx->dfl_pwq->plugged = true;
5318
5319	ctx->wq = wq;
5320	return ctx;
5321
5322	out_free:
5323	free_workqueue_attrs(new_attrs);
5324	apply_wqattrs_cleanup(ctx);
5325	return ERR_PTR(-ENOMEM);
5326	}
5327
5328	/* set attrs and install prepared pwqs, @ctx points to old pwqs on return */
5329	static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx)
5330	{
5331	int cpu;
5332
5333	/* all pwqs have been created successfully, let's install'em */
5334	mutex_lock(&ctx->wq->mutex);
5335
5336	copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs);
5337
5338	/* save the previous pwqs and install the new ones */
5339	for_each_possible_cpu(cpu)
5340	ctx->pwq_tbl[cpu] = install_unbound_pwq(ctx->wq, cpu,
5341	ctx->pwq_tbl[cpu]);
5342	ctx->dfl_pwq = install_unbound_pwq(ctx->wq, -1, ctx->dfl_pwq);
5343
5344	/* update node_nr_active->max */
5345	wq_update_node_max_active(ctx->wq, -1);
5346
5347	/* rescuer needs to respect wq cpumask changes */
5348	if (ctx->wq->rescuer)
5349	set_cpus_allowed_ptr(ctx->wq->rescuer->task,
5350	unbound_effective_cpumask(ctx->wq));
5351
5352	mutex_unlock(&ctx->wq->mutex);
5353	}
5354
5355	static int apply_workqueue_attrs_locked(struct workqueue_struct *wq,
5356	const struct workqueue_attrs *attrs)
5357	{
5358	struct apply_wqattrs_ctx *ctx;
5359
5360	/* only unbound workqueues can change attributes */
5361	if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
5362	return -EINVAL;
5363
5364	ctx = apply_wqattrs_prepare(wq, attrs, wq_unbound_cpumask);
5365	if (IS_ERR(ctx))
5366	return PTR_ERR(ctx);
5367
5368	/* the ctx has been prepared successfully, let's commit it */
5369	apply_wqattrs_commit(ctx);
5370	apply_wqattrs_cleanup(ctx);
5371
5372	return 0;
5373	}
5374
5375	/**
5376	* apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
5377	* @wq: the target workqueue
5378	* @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
5379	*
5380	* Apply @attrs to an unbound workqueue @wq. Unless disabled, this function maps
5381	* a separate pwq to each CPU pod with possibles CPUs in @attrs->cpumask so that
5382	* work items are affine to the pod it was issued on. Older pwqs are released as
5383	* in-flight work items finish. Note that a work item which repeatedly requeues
5384	* itself back-to-back will stay on its current pwq.
5385	*
5386	* Performs GFP_KERNEL allocations.
5387	*
5388	* Return: 0 on success and -errno on failure.
5389	*/
5390	int apply_workqueue_attrs(struct workqueue_struct *wq,
5391	const struct workqueue_attrs *attrs)
5392	{
5393	int ret;
5394
5395	mutex_lock(&wq_pool_mutex);
5396	ret = apply_workqueue_attrs_locked(wq, attrs);
5397	mutex_unlock(&wq_pool_mutex);
5398
5399	return ret;
5400	}
5401
5402	/**
5403	* unbound_wq_update_pwq - update a pwq slot for CPU hot[un]plug
5404	* @wq: the target workqueue
5405	* @cpu: the CPU to update the pwq slot for
5406	*
5407	* This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
5408	* %CPU_DOWN_FAILED. @cpu is in the same pod of the CPU being hot[un]plugged.
5409	*
5410	*
5411	* If pod affinity can't be adjusted due to memory allocation failure, it falls
5412	* back to @wq->dfl_pwq which may not be optimal but is always correct.
5413	*
5414	* Note that when the last allowed CPU of a pod goes offline for a workqueue
5415	* with a cpumask spanning multiple pods, the workers which were already
5416	* executing the work items for the workqueue will lose their CPU affinity and
5417	* may execute on any CPU. This is similar to how per-cpu workqueues behave on
5418	* CPU_DOWN. If a workqueue user wants strict affinity, it's the user's
5419	* responsibility to flush the work item from CPU_DOWN_PREPARE.
5420	*/
5421	static void unbound_wq_update_pwq(struct workqueue_struct *wq, int cpu)
5422	{
5423	struct pool_workqueue old_pwq = NULL, pwq;
5424	struct workqueue_attrs *target_attrs;
5425
5426	lockdep_assert_held(&wq_pool_mutex);
5427
5428	if (!(wq->flags & WQ_UNBOUND) \|\| wq->unbound_attrs->ordered)
5429	return;
5430
5431	/*
5432	* We don't wanna alloc/free wq_attrs for each wq for each CPU.
5433	* Let's use a preallocated one. The following buf is protected by
5434	* CPU hotplug exclusion.
5435	*/
5436	target_attrs = unbound_wq_update_pwq_attrs_buf;
5437
5438	copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
5439	wqattrs_actualize_cpumask(target_attrs, wq_unbound_cpumask);
5440
5441	/* nothing to do if the target cpumask matches the current pwq */
5442	wq_calc_pod_cpumask(target_attrs, cpu);
5443	if (wqattrs_equal(target_attrs, unbound_pwq(wq, cpu)->pool->attrs))
5444	return;
5445
5446	/* create a new pwq */
5447	pwq = alloc_unbound_pwq(wq, target_attrs);
5448	if (!pwq) {
5449	pr_warn("workqueue: allocation failed while updating CPU pod affinity of \"%s\"\n",
5450	wq->name);
5451	goto use_dfl_pwq;
5452	}
5453
5454	/* Install the new pwq. */
5455	mutex_lock(&wq->mutex);
5456	old_pwq = install_unbound_pwq(wq, cpu, pwq);
5457	goto out_unlock;
5458
5459	use_dfl_pwq:
5460	mutex_lock(&wq->mutex);
5461	pwq = unbound_pwq(wq, -1);
5462	raw_spin_lock_irq(&pwq->pool->lock);
5463	get_pwq(pwq);
5464	raw_spin_unlock_irq(&pwq->pool->lock);
5465	old_pwq = install_unbound_pwq(wq, cpu, pwq);
5466	out_unlock:
5467	mutex_unlock(&wq->mutex);
5468	put_pwq_unlocked(old_pwq);
5469	}
5470
5471	static int alloc_and_link_pwqs(struct workqueue_struct *wq)
5472	{
5473	bool highpri = wq->flags & WQ_HIGHPRI;
5474	int cpu, ret;
5475
5476	lockdep_assert_held(&wq_pool_mutex);
5477
5478	wq->cpu_pwq = alloc_percpu(struct pool_workqueue *);
5479	if (!wq->cpu_pwq)
5480	goto enomem;
5481
5482	if (!(wq->flags & WQ_UNBOUND)) {
5483	struct worker_pool __percpu *pools;
5484
5485	if (wq->flags & WQ_BH)
5486	pools = bh_worker_pools;
5487	else
5488	pools = cpu_worker_pools;
5489
5490	for_each_possible_cpu(cpu) {
5491	struct pool_workqueue **pwq_p;
5492	struct worker_pool *pool;
5493
5494	pool = &(per_cpu_ptr(pools, cpu)[highpri]);
5495	pwq_p = per_cpu_ptr(wq->cpu_pwq, cpu);
5496
5497	*pwq_p = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL,
5498	pool->node);
5499	if (!*pwq_p)
5500	goto enomem;
5501
5502	init_pwq(*pwq_p, wq, pool);
5503
5504	mutex_lock(&wq->mutex);
5505	link_pwq(*pwq_p);
5506	mutex_unlock(&wq->mutex);
5507	}
5508	return 0;
5509	}
5510
5511	if (wq->flags & __WQ_ORDERED) {
5512	struct pool_workqueue *dfl_pwq;
5513
5514	ret = apply_workqueue_attrs_locked(wq, ordered_wq_attrs[highpri]);
5515	/* there should only be single pwq for ordering guarantee */
5516	dfl_pwq = rcu_access_pointer(wq->dfl_pwq);
5517	WARN(!ret && (wq->pwqs.next != &dfl_pwq->pwqs_node \|\|
5518	wq->pwqs.prev != &dfl_pwq->pwqs_node),
5519	"ordering guarantee broken for workqueue %s\n", wq->name);
5520	} else {
5521	ret = apply_workqueue_attrs_locked(wq, unbound_std_wq_attrs[highpri]);
5522	}
5523
5524	return ret;
5525
5526	enomem:
5527	if (wq->cpu_pwq) {
5528	for_each_possible_cpu(cpu) {
5529	struct pool_workqueue pwq = per_cpu_ptr(wq->cpu_pwq, cpu);
5530
5531	if (pwq)
5532	kmem_cache_free(pwq_cache, pwq);
5533	}
5534	free_percpu(wq->cpu_pwq);
5535	wq->cpu_pwq = NULL;
5536	}
5537	return -ENOMEM;
5538	}
5539
5540	static int wq_clamp_max_active(int max_active, unsigned int flags,
5541	const char *name)
5542	{
5543	if (max_active < 1 \|\| max_active > WQ_MAX_ACTIVE)
5544	pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
5545	max_active, name, 1, WQ_MAX_ACTIVE);
5546
5547	return clamp_val(max_active, 1, WQ_MAX_ACTIVE);
5548	}
5549
5550	/*
5551	* Workqueues which may be used during memory reclaim should have a rescuer
5552	* to guarantee forward progress.
5553	*/
5554	static int init_rescuer(struct workqueue_struct *wq)
5555	{
5556	struct worker *rescuer;
5557	char id_buf[WORKER_ID_LEN];
5558	int ret;
5559
5560	lockdep_assert_held(&wq_pool_mutex);
5561
5562	if (!(wq->flags & WQ_MEM_RECLAIM))
5563	return 0;
5564
5565	rescuer = alloc_worker(NUMA_NO_NODE);
5566	if (!rescuer) {
5567	pr_err("workqueue: Failed to allocate a rescuer for wq \"%s\"\n",
5568	wq->name);
5569	return -ENOMEM;
5570	}
5571
5572	rescuer->rescue_wq = wq;
5573	format_worker_id(id_buf, sizeof(id_buf), rescuer, NULL);
5574
5575	rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", id_buf);
5576	if (IS_ERR(rescuer->task)) {
5577	ret = PTR_ERR(rescuer->task);
5578	pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe",
5579	wq->name, ERR_PTR(ret));
5580	kfree(rescuer);
5581	return ret;
5582	}
5583
5584	wq->rescuer = rescuer;
5585	if (wq->flags & WQ_UNBOUND)
5586	kthread_bind_mask(rescuer->task, unbound_effective_cpumask(wq));
5587	else
5588	kthread_bind_mask(rescuer->task, cpu_possible_mask);
5589	wake_up_process(rescuer->task);
5590
5591	return 0;
5592	}
5593
5594	/**
5595	* wq_adjust_max_active - update a wq's max_active to the current setting
5596	* @wq: target workqueue
5597	*
5598	* If @wq isn't freezing, set @wq->max_active to the saved_max_active and
5599	* activate inactive work items accordingly. If @wq is freezing, clear
5600	* @wq->max_active to zero.
5601	*/
5602	static void wq_adjust_max_active(struct workqueue_struct *wq)
5603	{
5604	bool activated;
5605	int new_max, new_min;
5606
5607	lockdep_assert_held(&wq->mutex);
5608
5609	if ((wq->flags & WQ_FREEZABLE) && workqueue_freezing) {
5610	new_max = 0;
5611	new_min = 0;
5612	} else {
5613	new_max = wq->saved_max_active;
5614	new_min = wq->saved_min_active;
5615	}
5616
5617	if (wq->max_active == new_max && wq->min_active == new_min)
5618	return;
5619
5620	/*
5621	* Update @wq->max/min_active and then kick inactive work items if more
5622	* active work items are allowed. This doesn't break work item ordering
5623	* because new work items are always queued behind existing inactive
5624	* work items if there are any.
5625	*/
5626	WRITE_ONCE(wq->max_active, new_max);
5627	WRITE_ONCE(wq->min_active, new_min);
5628
5629	if (wq->flags & WQ_UNBOUND)
5630	wq_update_node_max_active(wq, -1);
5631
5632	if (new_max == 0)
5633	return;
5634
5635	/*
5636	* Round-robin through pwq's activating the first inactive work item
5637	* until max_active is filled.
5638	*/
5639	do {
5640	struct pool_workqueue *pwq;
5641
5642	activated = false;
5643	for_each_pwq(pwq, wq) {
5644	unsigned long irq_flags;
5645
5646	/* can be called during early boot w/ irq disabled */
5647	raw_spin_lock_irqsave(&pwq->pool->lock, irq_flags);
5648	if (pwq_activate_first_inactive(pwq, true)) {
5649	activated = true;
5650	kick_pool(pwq->pool);
5651	}
5652	raw_spin_unlock_irqrestore(&pwq->pool->lock, irq_flags);
5653	}
5654	} while (activated);
5655	}
5656
5657	__printf(1, 0)
5658	static struct workqueue_struct __alloc_workqueue(const char fmt,
5659	unsigned int flags,
5660	int max_active, va_list args)
5661	{
5662	struct workqueue_struct *wq;
5663	size_t wq_size;
5664	int name_len;
5665
5666	if (flags & WQ_BH) {
5667	if (WARN_ON_ONCE(flags & ~__WQ_BH_ALLOWS))
5668	return NULL;
5669	if (WARN_ON_ONCE(max_active))
5670	return NULL;
5671	}
5672
5673	/* see the comment above the definition of WQ_POWER_EFFICIENT */
5674	if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
5675	flags \|= WQ_UNBOUND;
5676
5677	/* allocate wq and format name */
5678	if (flags & WQ_UNBOUND)
5679	wq_size = struct_size(wq, node_nr_active, nr_node_ids + 1);
5680	else
5681	wq_size = sizeof(*wq);
5682
5683	wq = kzalloc(wq_size, GFP_KERNEL);
5684	if (!wq)
5685	return NULL;
5686
5687	if (flags & WQ_UNBOUND) {
5688	wq->unbound_attrs = alloc_workqueue_attrs();
5689	if (!wq->unbound_attrs)
5690	goto err_free_wq;
5691	}
5692
5693	name_len = vsnprintf(wq->name, sizeof(wq->name), fmt, args);
5694
5695	if (name_len >= WQ_NAME_LEN)
5696	pr_warn_once("workqueue: name exceeds WQ_NAME_LEN. Truncating to: %s\n",
5697	wq->name);
5698
5699	if (flags & WQ_BH) {
5700	/*
5701	* BH workqueues always share a single execution context per CPU
5702	* and don't impose any max_active limit.
5703	*/
5704	max_active = INT_MAX;
5705	} else {
5706	max_active = max_active ?: WQ_DFL_ACTIVE;
5707	max_active = wq_clamp_max_active(max_active, flags, wq->name);
5708	}
5709
5710	/* init wq */
5711	wq->flags = flags;
5712	wq->max_active = max_active;
5713	wq->min_active = min(max_active, WQ_DFL_MIN_ACTIVE);
5714	wq->saved_max_active = wq->max_active;
5715	wq->saved_min_active = wq->min_active;
5716	mutex_init(&wq->mutex);
5717	atomic_set(&wq->nr_pwqs_to_flush, 0);
5718	INIT_LIST_HEAD(&wq->pwqs);
5719	INIT_LIST_HEAD(&wq->flusher_queue);
5720	INIT_LIST_HEAD(&wq->flusher_overflow);
5721	INIT_LIST_HEAD(&wq->maydays);
5722
5723	INIT_LIST_HEAD(&wq->list);
5724
5725	if (flags & WQ_UNBOUND) {
5726	if (alloc_node_nr_active(wq->node_nr_active) < 0)
5727	goto err_free_wq;
5728	}
5729
5730	/*
5731	* wq_pool_mutex protects the workqueues list, allocations of PWQs,
5732	* and the global freeze state.
5733	*/
5734	apply_wqattrs_lock();
5735
5736	if (alloc_and_link_pwqs(wq) < 0)
5737	goto err_unlock_free_node_nr_active;
5738
5739	mutex_lock(&wq->mutex);
5740	wq_adjust_max_active(wq);
5741	mutex_unlock(&wq->mutex);
5742
5743	list_add_tail_rcu(&wq->list, &workqueues);
5744
5745	if (wq_online && init_rescuer(wq) < 0)
5746	goto err_unlock_destroy;
5747
5748	apply_wqattrs_unlock();
5749
5750	if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq))
5751	goto err_destroy;
5752
5753	return wq;
5754
5755	err_unlock_free_node_nr_active:
5756	apply_wqattrs_unlock();
5757	/*
5758	* Failed alloc_and_link_pwqs() may leave pending pwq->release_work,
5759	* flushing the pwq_release_worker ensures that the pwq_release_workfn()
5760	* completes before calling kfree(wq).
5761	*/
5762	if (wq->flags & WQ_UNBOUND) {
5763	kthread_flush_worker(pwq_release_worker);
5764	free_node_nr_active(wq->node_nr_active);
5765	}
5766	err_free_wq:
5767	free_workqueue_attrs(wq->unbound_attrs);
5768	kfree(wq);
5769	return NULL;
5770	err_unlock_destroy:
5771	apply_wqattrs_unlock();
5772	err_destroy:
5773	destroy_workqueue(wq);
5774	return NULL;
5775	}
5776
5777	__printf(1, 4)
5778	struct workqueue_struct alloc_workqueue(const char fmt,
5779	unsigned int flags,
5780	int max_active, ...)
5781	{
5782	struct workqueue_struct *wq;
5783	va_list args;
5784
5785	va_start(args, max_active);
5786	wq = __alloc_workqueue(fmt, flags, max_active, args);
5787	va_end(args);
5788	if (!wq)
5789	return NULL;
5790
5791	wq_init_lockdep(wq);
5792
5793	return wq;
5794	}
5795	EXPORT_SYMBOL_GPL(alloc_workqueue);
5796
5797	#ifdef CONFIG_LOCKDEP
5798	__printf(1, 5)
5799	struct workqueue_struct *
5800	alloc_workqueue_lockdep_map(const char *fmt, unsigned int flags,
5801	int max_active, struct lockdep_map *lockdep_map, ...)
5802	{
5803	struct workqueue_struct *wq;
5804	va_list args;
5805
5806	va_start(args, lockdep_map);
5807	wq = __alloc_workqueue(fmt, flags, max_active, args);
5808	va_end(args);
5809	if (!wq)
5810	return NULL;
5811
5812	wq->lockdep_map = lockdep_map;
5813
5814	return wq;
5815	}
5816	EXPORT_SYMBOL_GPL(alloc_workqueue_lockdep_map);
5817	#endif
5818
5819	static bool pwq_busy(struct pool_workqueue *pwq)
5820	{
5821	int i;
5822
5823	for (i = 0; i < WORK_NR_COLORS; i++)
5824	if (pwq->nr_in_flight[i])
5825	return true;
5826
5827	if ((pwq != rcu_access_pointer(pwq->wq->dfl_pwq)) && (pwq->refcnt > 1))
5828	return true;
5829	if (!pwq_is_empty(pwq))
5830	return true;
5831
5832	return false;
5833	}
5834
5835	/**
5836	* destroy_workqueue - safely terminate a workqueue
5837	* @wq: target workqueue
5838	*
5839	* Safely destroy a workqueue. All work currently pending will be done first.
5840	*/
5841	void destroy_workqueue(struct workqueue_struct *wq)
5842	{
5843	struct pool_workqueue *pwq;
5844	int cpu;
5845
5846	/*
5847	* Remove it from sysfs first so that sanity check failure doesn't
5848	* lead to sysfs name conflicts.
5849	*/
5850	workqueue_sysfs_unregister(wq);
5851
5852	/* mark the workqueue destruction is in progress */
5853	mutex_lock(&wq->mutex);
5854	wq->flags \|= __WQ_DESTROYING;
5855	mutex_unlock(&wq->mutex);
5856
5857	/* drain it before proceeding with destruction */
5858	drain_workqueue(wq);
5859
5860	/* kill rescuer, if sanity checks fail, leave it w/o rescuer */
5861	if (wq->rescuer) {
5862	struct worker *rescuer = wq->rescuer;
5863
5864	/* this prevents new queueing */
5865	raw_spin_lock_irq(&wq_mayday_lock);
5866	wq->rescuer = NULL;
5867	raw_spin_unlock_irq(&wq_mayday_lock);
5868
5869	/* rescuer will empty maydays list before exiting */
5870	kthread_stop(rescuer->task);
5871	kfree(rescuer);
5872	}
5873
5874	/*
5875	* Sanity checks - grab all the locks so that we wait for all
5876	* in-flight operations which may do put_pwq().
5877	*/
5878	mutex_lock(&wq_pool_mutex);
5879	mutex_lock(&wq->mutex);
5880	for_each_pwq(pwq, wq) {
5881	raw_spin_lock_irq(&pwq->pool->lock);
5882	if (WARN_ON(pwq_busy(pwq))) {
5883	pr_warn("%s: %s has the following busy pwq\n",
5884	__func__, wq->name);
5885	show_pwq(pwq);
5886	raw_spin_unlock_irq(&pwq->pool->lock);
5887	mutex_unlock(&wq->mutex);
5888	mutex_unlock(&wq_pool_mutex);
5889	show_one_workqueue(wq);
5890	return;
5891	}
5892	raw_spin_unlock_irq(&pwq->pool->lock);
5893	}
5894	mutex_unlock(&wq->mutex);
5895
5896	/*
5897	* wq list is used to freeze wq, remove from list after
5898	* flushing is complete in case freeze races us.
5899	*/
5900	list_del_rcu(&wq->list);
5901	mutex_unlock(&wq_pool_mutex);
5902
5903	/*
5904	* We're the sole accessor of @wq. Directly access cpu_pwq and dfl_pwq
5905	* to put the base refs. @wq will be auto-destroyed from the last
5906	* pwq_put. RCU read lock prevents @wq from going away from under us.
5907	*/
5908	rcu_read_lock();
5909
5910	for_each_possible_cpu(cpu) {
5911	put_pwq_unlocked(unbound_pwq(wq, cpu));
5912	RCU_INIT_POINTER(*unbound_pwq_slot(wq, cpu), NULL);
5913	}
5914
5915	put_pwq_unlocked(unbound_pwq(wq, -1));
5916	RCU_INIT_POINTER(*unbound_pwq_slot(wq, -1), NULL);
5917
5918	rcu_read_unlock();
5919	}
5920	EXPORT_SYMBOL_GPL(destroy_workqueue);
5921
5922	/**
5923	* workqueue_set_max_active - adjust max_active of a workqueue
5924	* @wq: target workqueue
5925	* @max_active: new max_active value.
5926	*
5927	* Set max_active of @wq to @max_active. See the alloc_workqueue() function
5928	* comment.
5929	*
5930	* CONTEXT:
5931	* Don't call from IRQ context.
5932	*/
5933	void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
5934	{
5935	/* max_active doesn't mean anything for BH workqueues */
5936	if (WARN_ON(wq->flags & WQ_BH))
5937	return;
5938	/* disallow meddling with max_active for ordered workqueues */
5939	if (WARN_ON(wq->flags & __WQ_ORDERED))
5940	return;
5941
5942	max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
5943
5944	mutex_lock(&wq->mutex);
5945
5946	wq->saved_max_active = max_active;
5947	if (wq->flags & WQ_UNBOUND)
5948	wq->saved_min_active = min(wq->saved_min_active, max_active);
5949
5950	wq_adjust_max_active(wq);
5951
5952	mutex_unlock(&wq->mutex);
5953	}
5954	EXPORT_SYMBOL_GPL(workqueue_set_max_active);
5955
5956	/**
5957	* workqueue_set_min_active - adjust min_active of an unbound workqueue
5958	* @wq: target unbound workqueue
5959	* @min_active: new min_active value
5960	*
5961	* Set min_active of an unbound workqueue. Unlike other types of workqueues, an
5962	* unbound workqueue is not guaranteed to be able to process max_active
5963	* interdependent work items. Instead, an unbound workqueue is guaranteed to be
5964	* able to process min_active number of interdependent work items which is
5965	* %WQ_DFL_MIN_ACTIVE by default.
5966	*
5967	* Use this function to adjust the min_active value between 0 and the current
5968	* max_active.
5969	*/
5970	void workqueue_set_min_active(struct workqueue_struct *wq, int min_active)
5971	{
5972	/* min_active is only meaningful for non-ordered unbound workqueues */
5973	if (WARN_ON((wq->flags & (WQ_BH \| WQ_UNBOUND \| __WQ_ORDERED)) !=
5974	WQ_UNBOUND))
5975	return;
5976
5977	mutex_lock(&wq->mutex);
5978	wq->saved_min_active = clamp(min_active, 0, wq->saved_max_active);
5979	wq_adjust_max_active(wq);
5980	mutex_unlock(&wq->mutex);
5981	}
5982
5983	/**
5984	* current_work - retrieve %current task's work struct
5985	*
5986	* Determine if %current task is a workqueue worker and what it's working on.
5987	* Useful to find out the context that the %current task is running in.
5988	*
5989	* Return: work struct if %current task is a workqueue worker, %NULL otherwise.
5990	*/
5991	struct work_struct *current_work(void)
5992	{
5993	struct worker *worker = current_wq_worker();
5994
5995	return worker ? worker->current_work : NULL;
5996	}
5997	EXPORT_SYMBOL(current_work);
5998
5999	/**
6000	* current_is_workqueue_rescuer - is %current workqueue rescuer?
6001	*
6002	* Determine whether %current is a workqueue rescuer. Can be used from
6003	* work functions to determine whether it's being run off the rescuer task.
6004	*
6005	* Return: %true if %current is a workqueue rescuer. %false otherwise.
6006	*/
6007	bool current_is_workqueue_rescuer(void)
6008	{
6009	struct worker *worker = current_wq_worker();
6010
6011	return worker && worker->rescue_wq;
6012	}
6013
6014	/**
6015	* workqueue_congested - test whether a workqueue is congested
6016	* @cpu: CPU in question
6017	* @wq: target workqueue
6018	*
6019	* Test whether @wq's cpu workqueue for @cpu is congested. There is
6020	* no synchronization around this function and the test result is
6021	* unreliable and only useful as advisory hints or for debugging.
6022	*
6023	* If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU.
6024	*
6025	* With the exception of ordered workqueues, all workqueues have per-cpu
6026	* pool_workqueues, each with its own congested state. A workqueue being
6027	* congested on one CPU doesn't mean that the workqueue is contested on any
6028	* other CPUs.
6029	*
6030	* Return:
6031	* %true if congested, %false otherwise.
6032	*/
6033	bool workqueue_congested(int cpu, struct workqueue_struct *wq)
6034	{
6035	struct pool_workqueue *pwq;
6036	bool ret;
6037
6038	rcu_read_lock();
6039	preempt_disable();
6040
6041	if (cpu == WORK_CPU_UNBOUND)
6042	cpu = smp_processor_id();
6043
6044	pwq = *per_cpu_ptr(wq->cpu_pwq, cpu);
6045	ret = !list_empty(&pwq->inactive_works);
6046
6047	preempt_enable();
6048	rcu_read_unlock();
6049
6050	return ret;
6051	}
6052	EXPORT_SYMBOL_GPL(workqueue_congested);
6053
6054	/**
6055	* work_busy - test whether a work is currently pending or running
6056	* @work: the work to be tested
6057	*
6058	* Test whether @work is currently pending or running. There is no
6059	* synchronization around this function and the test result is
6060	* unreliable and only useful as advisory hints or for debugging.
6061	*
6062	* Return:
6063	* OR'd bitmask of WORK_BUSY_* bits.
6064	*/
6065	unsigned int work_busy(struct work_struct *work)
6066	{
6067	struct worker_pool *pool;
6068	unsigned long irq_flags;
6069	unsigned int ret = 0;
6070
6071	if (work_pending(work))
6072	ret \|= WORK_BUSY_PENDING;
6073
6074	rcu_read_lock();
6075	pool = get_work_pool(work);
6076	if (pool) {
6077	raw_spin_lock_irqsave(&pool->lock, irq_flags);
6078	if (find_worker_executing_work(pool, work))
6079	ret \|= WORK_BUSY_RUNNING;
6080	raw_spin_unlock_irqrestore(&pool->lock, irq_flags);
6081	}
6082	rcu_read_unlock();
6083
6084	return ret;
6085	}
6086	EXPORT_SYMBOL_GPL(work_busy);
6087
6088	/**
6089	* set_worker_desc - set description for the current work item
6090	* @fmt: printf-style format string
6091	* @...: arguments for the format string
6092	*
6093	* This function can be called by a running work function to describe what
6094	* the work item is about. If the worker task gets dumped, this
6095	* information will be printed out together to help debugging. The
6096	* description can be at most WORKER_DESC_LEN including the trailing '\0'.
6097	*/
6098	void set_worker_desc(const char *fmt, ...)
6099	{
6100	struct worker *worker = current_wq_worker();
6101	va_list args;
6102
6103	if (worker) {
6104	va_start(args, fmt);
6105	vsnprintf(worker->desc, sizeof(worker->desc), fmt, args);
6106	va_end(args);
6107	}
6108	}
6109	EXPORT_SYMBOL_GPL(set_worker_desc);
6110
6111	/**
6112	* print_worker_info - print out worker information and description
6113	* @log_lvl: the log level to use when printing
6114	* @task: target task
6115	*
6116	* If @task is a worker and currently executing a work item, print out the
6117	* name of the workqueue being serviced and worker description set with
6118	* set_worker_desc() by the currently executing work item.
6119	*
6120	* This function can be safely called on any task as long as the
6121	* task_struct itself is accessible. While safe, this function isn't
6122	* synchronized and may print out mixups or garbages of limited length.
6123	*/
6124	void print_worker_info(const char log_lvl, struct task_struct task)
6125	{
6126	work_func_t *fn = NULL;
6127	char name[WQ_NAME_LEN] = { };
6128	char desc[WORKER_DESC_LEN] = { };
6129	struct pool_workqueue *pwq = NULL;
6130	struct workqueue_struct *wq = NULL;
6131	struct worker *worker;
6132
6133	if (!(task->flags & PF_WQ_WORKER))
6134	return;
6135
6136	/*
6137	* This function is called without any synchronization and @task
6138	* could be in any state. Be careful with dereferences.
6139	*/
6140	worker = kthread_probe_data(task);
6141
6142	/*
6143	* Carefully copy the associated workqueue's workfn, name and desc.
6144	* Keep the original last '\0' in case the original is garbage.
6145	*/
6146	copy_from_kernel_nofault(&fn, &worker->current_func, sizeof(fn));
6147	copy_from_kernel_nofault(&pwq, &worker->current_pwq, sizeof(pwq));
6148	copy_from_kernel_nofault(&wq, &pwq->wq, sizeof(wq));
6149	copy_from_kernel_nofault(name, wq->name, sizeof(name) - 1);
6150	copy_from_kernel_nofault(desc, worker->desc, sizeof(desc) - 1);
6151
6152	if (fn \|\| name[0] \|\| desc[0]) {
6153	printk("%sWorkqueue: %s %ps", log_lvl, name, fn);
6154	if (strcmp(name, desc))
6155	pr_cont(" (%s)", desc);
6156	pr_cont("\n");
6157	}
6158	}
6159
6160	static void pr_cont_pool_info(struct worker_pool *pool)
6161	{
6162	pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask);
6163	if (pool->node != NUMA_NO_NODE)
6164	pr_cont(" node=%d", pool->node);
6165	pr_cont(" flags=0x%x", pool->flags);
6166	if (pool->flags & POOL_BH)
6167	pr_cont(" bh%s",
6168	pool->attrs->nice == HIGHPRI_NICE_LEVEL ? "-hi" : "");
6169	else
6170	pr_cont(" nice=%d", pool->attrs->nice);
6171	}
6172
6173	static void pr_cont_worker_id(struct worker *worker)
6174	{
6175	struct worker_pool *pool = worker->pool;
6176
6177	if (pool->flags & WQ_BH)
6178	pr_cont("bh%s",
6179	pool->attrs->nice == HIGHPRI_NICE_LEVEL ? "-hi" : "");
6180	else
6181	pr_cont("%d%s", task_pid_nr(worker->task),
6182	worker->rescue_wq ? "(RESCUER)" : "");
6183	}
6184
6185	struct pr_cont_work_struct {
6186	bool comma;
6187	work_func_t func;
6188	long ctr;
6189	};
6190
6191	static void pr_cont_work_flush(bool comma, work_func_t func, struct pr_cont_work_struct *pcwsp)
6192	{
6193	if (!pcwsp->ctr)
6194	goto out_record;
6195	if (func == pcwsp->func) {
6196	pcwsp->ctr++;
6197	return;
6198	}
6199	if (pcwsp->ctr == 1)
6200	pr_cont("%s %ps", pcwsp->comma ? "," : "", pcwsp->func);
6201	else
6202	pr_cont("%s %ld*%ps", pcwsp->comma ? "," : "", pcwsp->ctr, pcwsp->func);
6203	pcwsp->ctr = 0;
6204	out_record:
6205	if ((long)func == -1L)
6206	return;
6207	pcwsp->comma = comma;
6208	pcwsp->func = func;
6209	pcwsp->ctr = 1;
6210	}
6211
6212	static void pr_cont_work(bool comma, struct work_struct work, struct pr_cont_work_struct pcwsp)
6213	{
6214	if (work->func == wq_barrier_func) {
6215	struct wq_barrier *barr;
6216
6217	barr = container_of(work, struct wq_barrier, work);
6218
6219	pr_cont_work_flush(comma, (work_func_t)-1, pcwsp);
6220	pr_cont("%s BAR(%d)", comma ? "," : "",
6221	task_pid_nr(barr->task));
6222	} else {
6223	if (!comma)
6224	pr_cont_work_flush(comma, (work_func_t)-1, pcwsp);
6225	pr_cont_work_flush(comma, work->func, pcwsp);
6226	}
6227	}
6228
6229	static void show_pwq(struct pool_workqueue *pwq)
6230	{
6231	struct pr_cont_work_struct pcws = { .ctr = 0, };
6232	struct worker_pool *pool = pwq->pool;
6233	struct work_struct *work;
6234	struct worker *worker;
6235	bool has_in_flight = false, has_pending = false;
6236	int bkt;
6237
6238	pr_info(" pwq %d:", pool->id);
6239	pr_cont_pool_info(pool);
6240
6241	pr_cont(" active=%d refcnt=%d%s\n",
6242	pwq->nr_active, pwq->refcnt,
6243	!list_empty(&pwq->mayday_node) ? " MAYDAY" : "");
6244
6245	hash_for_each(pool->busy_hash, bkt, worker, hentry) {
6246	if (worker->current_pwq == pwq) {
6247	has_in_flight = true;
6248	break;
6249	}
6250	}
6251	if (has_in_flight) {
6252	bool comma = false;
6253
6254	pr_info(" in-flight:");
6255	hash_for_each(pool->busy_hash, bkt, worker, hentry) {
6256	if (worker->current_pwq != pwq)
6257	continue;
6258
6259	pr_cont(" %s", comma ? "," : "");
6260	pr_cont_worker_id(worker);
6261	pr_cont(":%ps", worker->current_func);
6262	list_for_each_entry(work, &worker->scheduled, entry)
6263	pr_cont_work(false, work, &pcws);
6264	pr_cont_work_flush(comma, (work_func_t)-1L, &pcws);
6265	comma = true;
6266	}
6267	pr_cont("\n");
6268	}
6269
6270	list_for_each_entry(work, &pool->worklist, entry) {
6271	if (get_work_pwq(work) == pwq) {
6272	has_pending = true;
6273	break;
6274	}
6275	}
6276	if (has_pending) {
6277	bool comma = false;
6278
6279	pr_info(" pending:");
6280	list_for_each_entry(work, &pool->worklist, entry) {
6281	if (get_work_pwq(work) != pwq)
6282	continue;
6283
6284	pr_cont_work(comma, work, &pcws);
6285	comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED);
6286	}
6287	pr_cont_work_flush(comma, (work_func_t)-1L, &pcws);
6288	pr_cont("\n");
6289	}
6290
6291	if (!list_empty(&pwq->inactive_works)) {
6292	bool comma = false;
6293
6294	pr_info(" inactive:");
6295	list_for_each_entry(work, &pwq->inactive_works, entry) {
6296	pr_cont_work(comma, work, &pcws);
6297	comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED);
6298	}
6299	pr_cont_work_flush(comma, (work_func_t)-1L, &pcws);
6300	pr_cont("\n");
6301	}
6302	}
6303
6304	/**
6305	* show_one_workqueue - dump state of specified workqueue
6306	* @wq: workqueue whose state will be printed
6307	*/
6308	void show_one_workqueue(struct workqueue_struct *wq)
6309	{
6310	struct pool_workqueue *pwq;
6311	bool idle = true;
6312	unsigned long irq_flags;
6313
6314	for_each_pwq(pwq, wq) {
6315	if (!pwq_is_empty(pwq)) {
6316	idle = false;
6317	break;
6318	}
6319	}
6320	if (idle) /* Nothing to print for idle workqueue */
6321	return;
6322
6323	pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags);
6324
6325	for_each_pwq(pwq, wq) {
6326	raw_spin_lock_irqsave(&pwq->pool->lock, irq_flags);
6327	if (!pwq_is_empty(pwq)) {
6328	/*
6329	* Defer printing to avoid deadlocks in console
6330	* drivers that queue work while holding locks
6331	* also taken in their write paths.
6332	*/
6333	printk_deferred_enter();
6334	show_pwq(pwq);
6335	printk_deferred_exit();
6336	}
6337	raw_spin_unlock_irqrestore(&pwq->pool->lock, irq_flags);
6338	/*
6339	* We could be printing a lot from atomic context, e.g.
6340	* sysrq-t -> show_all_workqueues(). Avoid triggering
6341	* hard lockup.
6342	*/
6343	touch_nmi_watchdog();
6344	}
6345
6346	}
6347
6348	/**
6349	* show_one_worker_pool - dump state of specified worker pool
6350	* @pool: worker pool whose state will be printed
6351	*/
6352	static void show_one_worker_pool(struct worker_pool *pool)
6353	{
6354	struct worker *worker;
6355	bool first = true;
6356	unsigned long irq_flags;
6357	unsigned long hung = 0;
6358
6359	raw_spin_lock_irqsave(&pool->lock, irq_flags);
6360	if (pool->nr_workers == pool->nr_idle)
6361	goto next_pool;
6362
6363	/* How long the first pending work is waiting for a worker. */
6364	if (!list_empty(&pool->worklist))
6365	hung = jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000;
6366
6367	/*
6368	* Defer printing to avoid deadlocks in console drivers that
6369	* queue work while holding locks also taken in their write
6370	* paths.
6371	*/
6372	printk_deferred_enter();
6373	pr_info("pool %d:", pool->id);
6374	pr_cont_pool_info(pool);
6375	pr_cont(" hung=%lus workers=%d", hung, pool->nr_workers);
6376	if (pool->manager)
6377	pr_cont(" manager: %d",
6378	task_pid_nr(pool->manager->task));
6379	list_for_each_entry(worker, &pool->idle_list, entry) {
6380	pr_cont(" %s", first ? "idle: " : "");
6381	pr_cont_worker_id(worker);
6382	first = false;
6383	}
6384	pr_cont("\n");
6385	printk_deferred_exit();
6386	next_pool:
6387	raw_spin_unlock_irqrestore(&pool->lock, irq_flags);
6388	/*
6389	* We could be printing a lot from atomic context, e.g.
6390	* sysrq-t -> show_all_workqueues(). Avoid triggering
6391	* hard lockup.
6392	*/
6393	touch_nmi_watchdog();
6394
6395	}
6396
6397	/**
6398	* show_all_workqueues - dump workqueue state
6399	*
6400	* Called from a sysrq handler and prints out all busy workqueues and pools.
6401	*/
6402	void show_all_workqueues(void)
6403	{
6404	struct workqueue_struct *wq;
6405	struct worker_pool *pool;
6406	int pi;
6407
6408	rcu_read_lock();
6409
6410	pr_info("Showing busy workqueues and worker pools:\n");
6411
6412	list_for_each_entry_rcu(wq, &workqueues, list)
6413	show_one_workqueue(wq);
6414
6415	for_each_pool(pool, pi)
6416	show_one_worker_pool(pool);
6417
6418	rcu_read_unlock();
6419	}
6420
6421	/**
6422	* show_freezable_workqueues - dump freezable workqueue state
6423	*
6424	* Called from try_to_freeze_tasks() and prints out all freezable workqueues
6425	* still busy.
6426	*/
6427	void show_freezable_workqueues(void)
6428	{
6429	struct workqueue_struct *wq;
6430
6431	rcu_read_lock();
6432
6433	pr_info("Showing freezable workqueues that are still busy:\n");
6434
6435	list_for_each_entry_rcu(wq, &workqueues, list) {
6436	if (!(wq->flags & WQ_FREEZABLE))
6437	continue;
6438	show_one_workqueue(wq);
6439	}
6440
6441	rcu_read_unlock();
6442	}
6443
6444	/* used to show worker information through /proc/PID/{comm,stat,status} */
6445	void wq_worker_comm(char buf, size_t size, struct task_struct task)
6446	{
6447	/* stabilize PF_WQ_WORKER and worker pool association */
6448	mutex_lock(&wq_pool_attach_mutex);
6449
6450	if (task->flags & PF_WQ_WORKER) {
6451	struct worker *worker = kthread_data(task);
6452	struct worker_pool *pool = worker->pool;
6453	int off;
6454
6455	off = format_worker_id(buf, size, worker, pool);
6456
6457	if (pool) {
6458	raw_spin_lock_irq(&pool->lock);
6459	/*
6460	* ->desc tracks information (wq name or
6461	* set_worker_desc()) for the latest execution. If
6462	* current, prepend '+', otherwise '-'.
6463	*/
6464	if (worker->desc[0] != '\0') {
6465	if (worker->current_work)
6466	scnprintf(buf + off, size - off, "+%s",
6467	worker->desc);
6468	else
6469	scnprintf(buf + off, size - off, "-%s",
6470	worker->desc);
6471	}
6472	raw_spin_unlock_irq(&pool->lock);
6473	}
6474	} else {
6475	strscpy(buf, task->comm, size);
6476	}
6477
6478	mutex_unlock(&wq_pool_attach_mutex);
6479	}
6480
6481	#ifdef CONFIG_SMP
6482
6483	/*
6484	* CPU hotplug.
6485	*
6486	* There are two challenges in supporting CPU hotplug. Firstly, there
6487	* are a lot of assumptions on strong associations among work, pwq and
6488	* pool which make migrating pending and scheduled works very
6489	* difficult to implement without impacting hot paths. Secondly,
6490	* worker pools serve mix of short, long and very long running works making
6491	* blocked draining impractical.
6492	*
6493	* This is solved by allowing the pools to be disassociated from the CPU
6494	* running as an unbound one and allowing it to be reattached later if the
6495	* cpu comes back online.
6496	*/
6497
6498	static void unbind_workers(int cpu)
6499	{
6500	struct worker_pool *pool;
6501	struct worker *worker;
6502
6503	for_each_cpu_worker_pool(pool, cpu) {
6504	mutex_lock(&wq_pool_attach_mutex);
6505	raw_spin_lock_irq(&pool->lock);
6506
6507	/*
6508	* We've blocked all attach/detach operations. Make all workers
6509	* unbound and set DISASSOCIATED. Before this, all workers
6510	* must be on the cpu. After this, they may become diasporas.
6511	* And the preemption disabled section in their sched callbacks
6512	* are guaranteed to see WORKER_UNBOUND since the code here
6513	* is on the same cpu.
6514	*/
6515	for_each_pool_worker(worker, pool)
6516	worker->flags \|= WORKER_UNBOUND;
6517
6518	pool->flags \|= POOL_DISASSOCIATED;
6519
6520	/*
6521	* The handling of nr_running in sched callbacks are disabled
6522	* now. Zap nr_running. After this, nr_running stays zero and
6523	* need_more_worker() and keep_working() are always true as
6524	* long as the worklist is not empty. This pool now behaves as
6525	* an unbound (in terms of concurrency management) pool which
6526	* are served by workers tied to the pool.
6527	*/
6528	pool->nr_running = 0;
6529
6530	/*
6531	* With concurrency management just turned off, a busy
6532	* worker blocking could lead to lengthy stalls. Kick off
6533	* unbound chain execution of currently pending work items.
6534	*/
6535	kick_pool(pool);
6536
6537	raw_spin_unlock_irq(&pool->lock);
6538
6539	for_each_pool_worker(worker, pool)
6540	unbind_worker(worker);
6541
6542	mutex_unlock(&wq_pool_attach_mutex);
6543	}
6544	}
6545
6546	/**
6547	* rebind_workers - rebind all workers of a pool to the associated CPU
6548	* @pool: pool of interest
6549	*
6550	* @pool->cpu is coming online. Rebind all workers to the CPU.
6551	*/
6552	static void rebind_workers(struct worker_pool *pool)
6553	{
6554	struct worker *worker;
6555
6556	lockdep_assert_held(&wq_pool_attach_mutex);
6557
6558	/*
6559	* Restore CPU affinity of all workers. As all idle workers should
6560	* be on the run-queue of the associated CPU before any local
6561	* wake-ups for concurrency management happen, restore CPU affinity
6562	* of all workers first and then clear UNBOUND. As we're called
6563	* from CPU_ONLINE, the following shouldn't fail.
6564	*/
6565	for_each_pool_worker(worker, pool) {
6566	kthread_set_per_cpu(worker->task, pool->cpu);
6567	WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
6568	pool_allowed_cpus(pool)) < 0);
6569	}
6570
6571	raw_spin_lock_irq(&pool->lock);
6572
6573	pool->flags &= ~POOL_DISASSOCIATED;
6574
6575	for_each_pool_worker(worker, pool) {
6576	unsigned int worker_flags = worker->flags;
6577
6578	/*
6579	* We want to clear UNBOUND but can't directly call
6580	* worker_clr_flags() or adjust nr_running. Atomically
6581	* replace UNBOUND with another NOT_RUNNING flag REBOUND.
6582	* @worker will clear REBOUND using worker_clr_flags() when
6583	* it initiates the next execution cycle thus restoring
6584	* concurrency management. Note that when or whether
6585	* @worker clears REBOUND doesn't affect correctness.
6586	*
6587	* WRITE_ONCE() is necessary because @worker->flags may be
6588	* tested without holding any lock in
6589	* wq_worker_running(). Without it, NOT_RUNNING test may
6590	* fail incorrectly leading to premature concurrency
6591	* management operations.
6592	*/
6593	WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND));
6594	worker_flags \|= WORKER_REBOUND;
6595	worker_flags &= ~WORKER_UNBOUND;
6596	WRITE_ONCE(worker->flags, worker_flags);
6597	}
6598
6599	raw_spin_unlock_irq(&pool->lock);
6600	}
6601
6602	/**
6603	* restore_unbound_workers_cpumask - restore cpumask of unbound workers
6604	* @pool: unbound pool of interest
6605	* @cpu: the CPU which is coming up
6606	*
6607	* An unbound pool may end up with a cpumask which doesn't have any online
6608	* CPUs. When a worker of such pool get scheduled, the scheduler resets
6609	* its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
6610	* online CPU before, cpus_allowed of all its workers should be restored.
6611	*/
6612	static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
6613	{
6614	static cpumask_t cpumask;
6615	struct worker *worker;
6616
6617	lockdep_assert_held(&wq_pool_attach_mutex);
6618
6619	/* is @cpu allowed for @pool? */
6620	if (!cpumask_test_cpu(cpu, pool->attrs->cpumask))
6621	return;
6622
6623	cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask);
6624
6625	/* as we're called from CPU_ONLINE, the following shouldn't fail */
6626	for_each_pool_worker(worker, pool)
6627	WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0);
6628	}
6629
6630	int workqueue_prepare_cpu(unsigned int cpu)
6631	{
6632	struct worker_pool *pool;
6633
6634	for_each_cpu_worker_pool(pool, cpu) {
6635	if (pool->nr_workers)
6636	continue;
6637	if (!create_worker(pool))
6638	return -ENOMEM;
6639	}
6640	return 0;
6641	}
6642
6643	int workqueue_online_cpu(unsigned int cpu)
6644	{
6645	struct worker_pool *pool;
6646	struct workqueue_struct *wq;
6647	int pi;
6648
6649	mutex_lock(&wq_pool_mutex);
6650
6651	cpumask_set_cpu(cpu, wq_online_cpumask);
6652
6653	for_each_pool(pool, pi) {
6654	/* BH pools aren't affected by hotplug */
6655	if (pool->flags & POOL_BH)
6656	continue;
6657
6658	mutex_lock(&wq_pool_attach_mutex);
6659	if (pool->cpu == cpu)
6660	rebind_workers(pool);
6661	else if (pool->cpu < 0)
6662	restore_unbound_workers_cpumask(pool, cpu);
6663	mutex_unlock(&wq_pool_attach_mutex);
6664	}
6665
6666	/* update pod affinity of unbound workqueues */
6667	list_for_each_entry(wq, &workqueues, list) {
6668	struct workqueue_attrs *attrs = wq->unbound_attrs;
6669
6670	if (attrs) {
6671	const struct wq_pod_type *pt = wqattrs_pod_type(attrs);
6672	int tcpu;
6673
6674	for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]])
6675	unbound_wq_update_pwq(wq, tcpu);
6676
6677	mutex_lock(&wq->mutex);
6678	wq_update_node_max_active(wq, -1);
6679	mutex_unlock(&wq->mutex);
6680	}
6681	}
6682
6683	mutex_unlock(&wq_pool_mutex);
6684	return 0;
6685	}
6686
6687	int workqueue_offline_cpu(unsigned int cpu)
6688	{
6689	struct workqueue_struct *wq;
6690
6691	/* unbinding per-cpu workers should happen on the local CPU */
6692	if (WARN_ON(cpu != smp_processor_id()))
6693	return -1;
6694
6695	unbind_workers(cpu);
6696
6697	/* update pod affinity of unbound workqueues */
6698	mutex_lock(&wq_pool_mutex);
6699
6700	cpumask_clear_cpu(cpu, wq_online_cpumask);
6701
6702	list_for_each_entry(wq, &workqueues, list) {
6703	struct workqueue_attrs *attrs = wq->unbound_attrs;
6704
6705	if (attrs) {
6706	const struct wq_pod_type *pt = wqattrs_pod_type(attrs);
6707	int tcpu;
6708
6709	for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]])
6710	unbound_wq_update_pwq(wq, tcpu);
6711
6712	mutex_lock(&wq->mutex);
6713	wq_update_node_max_active(wq, cpu);
6714	mutex_unlock(&wq->mutex);
6715	}
6716	}
6717	mutex_unlock(&wq_pool_mutex);
6718
6719	return 0;
6720	}
6721
6722	struct work_for_cpu {
6723	struct work_struct work;
6724	long (fn)(void );
6725	void *arg;
6726	long ret;
6727	};
6728
6729	static void work_for_cpu_fn(struct work_struct *work)
6730	{
6731	struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work);
6732
6733	wfc->ret = wfc->fn(wfc->arg);
6734	}
6735
6736	/**
6737	* work_on_cpu_key - run a function in thread context on a particular cpu
6738	* @cpu: the cpu to run on
6739	* @fn: the function to run
6740	* @arg: the function arg
6741	* @key: The lock class key for lock debugging purposes
6742	*
6743	* It is up to the caller to ensure that the cpu doesn't go offline.
6744	* The caller must not hold any locks which would prevent @fn from completing.
6745	*
6746	* Return: The value @fn returns.
6747	*/
6748	long work_on_cpu_key(int cpu, long (fn)(void ),
6749	void arg, struct lock_class_key key)
6750	{
6751	struct work_for_cpu wfc = { .fn = fn, .arg = arg };
6752
6753	INIT_WORK_ONSTACK_KEY(&wfc.work, work_for_cpu_fn, key);
6754	schedule_work_on(cpu, &wfc.work);
6755	flush_work(&wfc.work);
6756	destroy_work_on_stack(&wfc.work);
6757	return wfc.ret;
6758	}
6759	EXPORT_SYMBOL_GPL(work_on_cpu_key);
6760
6761	/**
6762	* work_on_cpu_safe_key - run a function in thread context on a particular cpu
6763	* @cpu: the cpu to run on
6764	* @fn: the function to run
6765	* @arg: the function argument
6766	* @key: The lock class key for lock debugging purposes
6767	*
6768	* Disables CPU hotplug and calls work_on_cpu(). The caller must not hold
6769	* any locks which would prevent @fn from completing.
6770	*
6771	* Return: The value @fn returns.
6772	*/
6773	long work_on_cpu_safe_key(int cpu, long (fn)(void ),
6774	void arg, struct lock_class_key key)
6775	{
6776	long ret = -ENODEV;
6777
6778	cpus_read_lock();
6779	if (cpu_online(cpu))
6780	ret = work_on_cpu_key(cpu, fn, arg, key);
6781	cpus_read_unlock();
6782	return ret;
6783	}
6784	EXPORT_SYMBOL_GPL(work_on_cpu_safe_key);
6785	#endif /* CONFIG_SMP */
6786
6787	#ifdef CONFIG_FREEZER
6788
6789	/**
6790	* freeze_workqueues_begin - begin freezing workqueues
6791	*
6792	* Start freezing workqueues. After this function returns, all freezable
6793	* workqueues will queue new works to their inactive_works list instead of
6794	* pool->worklist.
6795	*
6796	* CONTEXT:
6797	* Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
6798	*/
6799	void freeze_workqueues_begin(void)
6800	{
6801	struct workqueue_struct *wq;
6802
6803	mutex_lock(&wq_pool_mutex);
6804
6805	WARN_ON_ONCE(workqueue_freezing);
6806	workqueue_freezing = true;
6807
6808	list_for_each_entry(wq, &workqueues, list) {
6809	mutex_lock(&wq->mutex);
6810	wq_adjust_max_active(wq);
6811	mutex_unlock(&wq->mutex);
6812	}
6813
6814	mutex_unlock(&wq_pool_mutex);
6815	}
6816
6817	/**
6818	* freeze_workqueues_busy - are freezable workqueues still busy?
6819	*
6820	* Check whether freezing is complete. This function must be called
6821	* between freeze_workqueues_begin() and thaw_workqueues().
6822	*
6823	* CONTEXT:
6824	* Grabs and releases wq_pool_mutex.
6825	*
6826	* Return:
6827	* %true if some freezable workqueues are still busy. %false if freezing
6828	* is complete.
6829	*/
6830	bool freeze_workqueues_busy(void)
6831	{
6832	bool busy = false;
6833	struct workqueue_struct *wq;
6834	struct pool_workqueue *pwq;
6835
6836	mutex_lock(&wq_pool_mutex);
6837
6838	WARN_ON_ONCE(!workqueue_freezing);
6839
6840	list_for_each_entry(wq, &workqueues, list) {
6841	if (!(wq->flags & WQ_FREEZABLE))
6842	continue;
6843	/*
6844	* nr_active is monotonically decreasing. It's safe
6845	* to peek without lock.
6846	*/
6847	rcu_read_lock();
6848	for_each_pwq(pwq, wq) {
6849	WARN_ON_ONCE(pwq->nr_active < 0);
6850	if (pwq->nr_active) {
6851	busy = true;
6852	rcu_read_unlock();
6853	goto out_unlock;
6854	}
6855	}
6856	rcu_read_unlock();
6857	}
6858	out_unlock:
6859	mutex_unlock(&wq_pool_mutex);
6860	return busy;
6861	}
6862
6863	/**
6864	* thaw_workqueues - thaw workqueues
6865	*
6866	* Thaw workqueues. Normal queueing is restored and all collected
6867	* frozen works are transferred to their respective pool worklists.
6868	*
6869	* CONTEXT:
6870	* Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
6871	*/
6872	void thaw_workqueues(void)
6873	{
6874	struct workqueue_struct *wq;
6875
6876	mutex_lock(&wq_pool_mutex);
6877
6878	if (!workqueue_freezing)
6879	goto out_unlock;
6880
6881	workqueue_freezing = false;
6882
6883	/* restore max_active and repopulate worklist */
6884	list_for_each_entry(wq, &workqueues, list) {
6885	mutex_lock(&wq->mutex);
6886	wq_adjust_max_active(wq);
6887	mutex_unlock(&wq->mutex);
6888	}
6889
6890	out_unlock:
6891	mutex_unlock(&wq_pool_mutex);
6892	}
6893	#endif /* CONFIG_FREEZER */
6894
6895	static int workqueue_apply_unbound_cpumask(const cpumask_var_t unbound_cpumask)
6896	{
6897	LIST_HEAD(ctxs);
6898	int ret = 0;
6899	struct workqueue_struct *wq;
6900	struct apply_wqattrs_ctx ctx, n;
6901
6902	lockdep_assert_held(&wq_pool_mutex);
6903
6904	list_for_each_entry(wq, &workqueues, list) {
6905	if (!(wq->flags & WQ_UNBOUND) \|\| (wq->flags & __WQ_DESTROYING))
6906	continue;
6907
6908	ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs, unbound_cpumask);
6909	if (IS_ERR(ctx)) {
6910	ret = PTR_ERR(ctx);
6911	break;
6912	}
6913
6914	list_add_tail(&ctx->list, &ctxs);
6915	}
6916
6917	list_for_each_entry_safe(ctx, n, &ctxs, list) {
6918	if (!ret)
6919	apply_wqattrs_commit(ctx);
6920	apply_wqattrs_cleanup(ctx);
6921	}
6922
6923	if (!ret) {
6924	mutex_lock(&wq_pool_attach_mutex);
6925	cpumask_copy(wq_unbound_cpumask, unbound_cpumask);
6926	mutex_unlock(&wq_pool_attach_mutex);
6927	}
6928	return ret;
6929	}
6930
6931	/**
6932	* workqueue_unbound_exclude_cpumask - Exclude given CPUs from unbound cpumask
6933	* @exclude_cpumask: the cpumask to be excluded from wq_unbound_cpumask
6934	*
6935	* This function can be called from cpuset code to provide a set of isolated
6936	* CPUs that should be excluded from wq_unbound_cpumask.
6937	*/
6938	int workqueue_unbound_exclude_cpumask(cpumask_var_t exclude_cpumask)
6939	{
6940	cpumask_var_t cpumask;
6941	int ret = 0;
6942
6943	if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL))
6944	return -ENOMEM;
6945
6946	mutex_lock(&wq_pool_mutex);
6947
6948	/*
6949	* If the operation fails, it will fall back to
6950	* wq_requested_unbound_cpumask which is initially set to
6951	* (HK_TYPE_WQ ∩ HK_TYPE_DOMAIN) house keeping mask and rewritten
6952	* by any subsequent write to workqueue/cpumask sysfs file.
6953	*/
6954	if (!cpumask_andnot(cpumask, wq_requested_unbound_cpumask, exclude_cpumask))
6955	cpumask_copy(cpumask, wq_requested_unbound_cpumask);
6956	if (!cpumask_equal(cpumask, wq_unbound_cpumask))
6957	ret = workqueue_apply_unbound_cpumask(cpumask);
6958
6959	/* Save the current isolated cpumask & export it via sysfs */
6960	if (!ret)
6961	cpumask_copy(wq_isolated_cpumask, exclude_cpumask);
6962
6963	mutex_unlock(&wq_pool_mutex);
6964	free_cpumask_var(cpumask);
6965	return ret;
6966	}
6967
6968	static int parse_affn_scope(const char *val)
6969	{
6970	int i;
6971
6972	for (i = 0; i < ARRAY_SIZE(wq_affn_names); i++) {
6973	if (!strncasecmp(val, wq_affn_names[i], strlen(wq_affn_names[i])))
6974	return i;
6975	}
6976	return -EINVAL;
6977	}
6978
6979	static int wq_affn_dfl_set(const char val, const struct kernel_param kp)
6980	{
6981	struct workqueue_struct *wq;
6982	int affn, cpu;
6983
6984	affn = parse_affn_scope(val);
6985	if (affn < 0)
6986	return affn;
6987	if (affn == WQ_AFFN_DFL)
6988	return -EINVAL;
6989
6990	cpus_read_lock();
6991	mutex_lock(&wq_pool_mutex);
6992
6993	wq_affn_dfl = affn;
6994
6995	list_for_each_entry(wq, &workqueues, list) {
6996	for_each_online_cpu(cpu)
6997	unbound_wq_update_pwq(wq, cpu);
6998	}
6999
7000	mutex_unlock(&wq_pool_mutex);
7001	cpus_read_unlock();
7002
7003	return 0;
7004	}
7005
7006	static int wq_affn_dfl_get(char buffer, const struct kernel_param kp)
7007	{
7008	return scnprintf(buffer, PAGE_SIZE, "%s\n", wq_affn_names[wq_affn_dfl]);
7009	}
7010
7011	static const struct kernel_param_ops wq_affn_dfl_ops = {
7012	.set = wq_affn_dfl_set,
7013	.get = wq_affn_dfl_get,
7014	};
7015
7016	module_param_cb(default_affinity_scope, &wq_affn_dfl_ops, NULL, 0644);
7017
7018	#ifdef CONFIG_SYSFS
7019	/*
7020	* Workqueues with WQ_SYSFS flag set is visible to userland via
7021	* /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
7022	* following attributes.
7023	*
7024	* per_cpu RO bool : whether the workqueue is per-cpu or unbound
7025	* max_active RW int : maximum number of in-flight work items
7026	*
7027	* Unbound workqueues have the following extra attributes.
7028	*
7029	* nice RW int : nice value of the workers
7030	* cpumask RW mask : bitmask of allowed CPUs for the workers
7031	* affinity_scope RW str : worker CPU affinity scope (cache, numa, none)
7032	* affinity_strict RW bool : worker CPU affinity is strict
7033	*/
7034	struct wq_device {
7035	struct workqueue_struct *wq;
7036	struct device dev;
7037	};
7038
7039	static struct workqueue_struct dev_to_wq(struct device dev)
7040	{
7041	struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
7042
7043	return wq_dev->wq;
7044	}
7045
7046	static ssize_t per_cpu_show(struct device dev, struct device_attribute attr,
7047	char *buf)
7048	{
7049	struct workqueue_struct *wq = dev_to_wq(dev);
7050
7051	return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND));
7052	}
7053	static DEVICE_ATTR_RO(per_cpu);
7054
7055	static ssize_t max_active_show(struct device *dev,
7056	struct device_attribute attr, char buf)
7057	{
7058	struct workqueue_struct *wq = dev_to_wq(dev);
7059
7060	return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active);
7061	}
7062
7063	static ssize_t max_active_store(struct device *dev,
7064	struct device_attribute attr, const char buf,
7065	size_t count)
7066	{
7067	struct workqueue_struct *wq = dev_to_wq(dev);
7068	int val;
7069
7070	if (sscanf(buf, "%d", &val) != 1 \|\| val <= 0)
7071	return -EINVAL;
7072
7073	workqueue_set_max_active(wq, val);
7074	return count;
7075	}
7076	static DEVICE_ATTR_RW(max_active);
7077
7078	static struct attribute *wq_sysfs_attrs[] = {
7079	&dev_attr_per_cpu.attr,
7080	&dev_attr_max_active.attr,
7081	NULL,
7082	};
7083	ATTRIBUTE_GROUPS(wq_sysfs);
7084
7085	static ssize_t wq_nice_show(struct device dev, struct device_attribute attr,
7086	char *buf)
7087	{
7088	struct workqueue_struct *wq = dev_to_wq(dev);
7089	int written;
7090
7091	mutex_lock(&wq->mutex);
7092	written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice);
7093	mutex_unlock(&wq->mutex);
7094
7095	return written;
7096	}
7097
7098	/* prepare workqueue_attrs for sysfs store operations */
7099	static struct workqueue_attrs wq_sysfs_prep_attrs(struct workqueue_struct wq)
7100	{
7101	struct workqueue_attrs *attrs;
7102
7103	lockdep_assert_held(&wq_pool_mutex);
7104
7105	attrs = alloc_workqueue_attrs();
7106	if (!attrs)
7107	return NULL;
7108
7109	copy_workqueue_attrs(attrs, wq->unbound_attrs);
7110	return attrs;
7111	}
7112
7113	static ssize_t wq_nice_store(struct device dev, struct device_attribute attr,
7114	const char *buf, size_t count)
7115	{
7116	struct workqueue_struct *wq = dev_to_wq(dev);
7117	struct workqueue_attrs *attrs;
7118	int ret = -ENOMEM;
7119
7120	apply_wqattrs_lock();
7121
7122	attrs = wq_sysfs_prep_attrs(wq);
7123	if (!attrs)
7124	goto out_unlock;
7125
7126	if (sscanf(buf, "%d", &attrs->nice) == 1 &&
7127	attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE)
7128	ret = apply_workqueue_attrs_locked(wq, attrs);
7129	else
7130	ret = -EINVAL;
7131
7132	out_unlock:
7133	apply_wqattrs_unlock();
7134	free_workqueue_attrs(attrs);
7135	return ret ?: count;
7136	}
7137
7138	static ssize_t wq_cpumask_show(struct device *dev,
7139	struct device_attribute attr, char buf)
7140	{
7141	struct workqueue_struct *wq = dev_to_wq(dev);
7142	int written;
7143
7144	mutex_lock(&wq->mutex);
7145	written = scnprintf(buf, PAGE_SIZE, "%*pb\n",
7146	cpumask_pr_args(wq->unbound_attrs->cpumask));
7147	mutex_unlock(&wq->mutex);
7148	return written;
7149	}
7150
7151	static ssize_t wq_cpumask_store(struct device *dev,
7152	struct device_attribute *attr,
7153	const char *buf, size_t count)
7154	{
7155	struct workqueue_struct *wq = dev_to_wq(dev);
7156	struct workqueue_attrs *attrs;
7157	int ret = -ENOMEM;
7158
7159	apply_wqattrs_lock();
7160
7161	attrs = wq_sysfs_prep_attrs(wq);
7162	if (!attrs)
7163	goto out_unlock;
7164
7165	ret = cpumask_parse(buf, attrs->cpumask);
7166	if (!ret)
7167	ret = apply_workqueue_attrs_locked(wq, attrs);
7168
7169	out_unlock:
7170	apply_wqattrs_unlock();
7171	free_workqueue_attrs(attrs);
7172	return ret ?: count;
7173	}
7174
7175	static ssize_t wq_affn_scope_show(struct device *dev,
7176	struct device_attribute attr, char buf)
7177	{
7178	struct workqueue_struct *wq = dev_to_wq(dev);
7179	int written;
7180
7181	mutex_lock(&wq->mutex);
7182	if (wq->unbound_attrs->affn_scope == WQ_AFFN_DFL)
7183	written = scnprintf(buf, PAGE_SIZE, "%s (%s)\n",
7184	wq_affn_names[WQ_AFFN_DFL],
7185	wq_affn_names[wq_affn_dfl]);
7186	else
7187	written = scnprintf(buf, PAGE_SIZE, "%s\n",
7188	wq_affn_names[wq->unbound_attrs->affn_scope]);
7189	mutex_unlock(&wq->mutex);
7190
7191	return written;
7192	}
7193
7194	static ssize_t wq_affn_scope_store(struct device *dev,
7195	struct device_attribute *attr,
7196	const char *buf, size_t count)
7197	{
7198	struct workqueue_struct *wq = dev_to_wq(dev);
7199	struct workqueue_attrs *attrs;
7200	int affn, ret = -ENOMEM;
7201
7202	affn = parse_affn_scope(buf);
7203	if (affn < 0)
7204	return affn;
7205
7206	apply_wqattrs_lock();
7207	attrs = wq_sysfs_prep_attrs(wq);
7208	if (attrs) {
7209	attrs->affn_scope = affn;
7210	ret = apply_workqueue_attrs_locked(wq, attrs);
7211	}
7212	apply_wqattrs_unlock();
7213	free_workqueue_attrs(attrs);
7214	return ret ?: count;
7215	}
7216
7217	static ssize_t wq_affinity_strict_show(struct device *dev,
7218	struct device_attribute attr, char buf)
7219	{
7220	struct workqueue_struct *wq = dev_to_wq(dev);
7221
7222	return scnprintf(buf, PAGE_SIZE, "%d\n",
7223	wq->unbound_attrs->affn_strict);
7224	}
7225
7226	static ssize_t wq_affinity_strict_store(struct device *dev,
7227	struct device_attribute *attr,
7228	const char *buf, size_t count)
7229	{
7230	struct workqueue_struct *wq = dev_to_wq(dev);
7231	struct workqueue_attrs *attrs;
7232	int v, ret = -ENOMEM;
7233
7234	if (sscanf(buf, "%d", &v) != 1)
7235	return -EINVAL;
7236
7237	apply_wqattrs_lock();
7238	attrs = wq_sysfs_prep_attrs(wq);
7239	if (attrs) {
7240	attrs->affn_strict = (bool)v;
7241	ret = apply_workqueue_attrs_locked(wq, attrs);
7242	}
7243	apply_wqattrs_unlock();
7244	free_workqueue_attrs(attrs);
7245	return ret ?: count;
7246	}
7247
7248	static struct device_attribute wq_sysfs_unbound_attrs[] = {
7249	__ATTR(nice, 0644, wq_nice_show, wq_nice_store),
7250	__ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store),
7251	__ATTR(affinity_scope, 0644, wq_affn_scope_show, wq_affn_scope_store),
7252	__ATTR(affinity_strict, 0644, wq_affinity_strict_show, wq_affinity_strict_store),
7253	__ATTR_NULL,
7254	};
7255
7256	static const struct bus_type wq_subsys = {
7257	.name = "workqueue",
7258	.dev_groups = wq_sysfs_groups,
7259	};
7260
7261	/**
7262	* workqueue_set_unbound_cpumask - Set the low-level unbound cpumask
7263	* @cpumask: the cpumask to set
7264	*
7265	* The low-level workqueues cpumask is a global cpumask that limits
7266	* the affinity of all unbound workqueues. This function check the @cpumask
7267	* and apply it to all unbound workqueues and updates all pwqs of them.
7268	*
7269	* Return: 0 - Success
7270	* -EINVAL - Invalid @cpumask
7271	* -ENOMEM - Failed to allocate memory for attrs or pwqs.
7272	*/
7273	static int workqueue_set_unbound_cpumask(cpumask_var_t cpumask)
7274	{
7275	int ret = -EINVAL;
7276
7277	/*
7278	* Not excluding isolated cpus on purpose.
7279	* If the user wishes to include them, we allow that.
7280	*/
7281	cpumask_and(cpumask, cpumask, cpu_possible_mask);
7282	if (!cpumask_empty(cpumask)) {
7283	ret = 0;
7284	apply_wqattrs_lock();
7285	if (!cpumask_equal(cpumask, wq_unbound_cpumask))
7286	ret = workqueue_apply_unbound_cpumask(cpumask);
7287	if (!ret)
7288	cpumask_copy(wq_requested_unbound_cpumask, cpumask);
7289	apply_wqattrs_unlock();
7290	}
7291
7292	return ret;
7293	}
7294
7295	static ssize_t __wq_cpumask_show(struct device *dev,
7296	struct device_attribute attr, char buf, cpumask_var_t mask)
7297	{
7298	int written;
7299
7300	mutex_lock(&wq_pool_mutex);
7301	written = scnprintf(buf, PAGE_SIZE, "%*pb\n", cpumask_pr_args(mask));
7302	mutex_unlock(&wq_pool_mutex);
7303
7304	return written;
7305	}
7306
7307	static ssize_t cpumask_requested_show(struct device *dev,
7308	struct device_attribute attr, char buf)
7309	{
7310	return __wq_cpumask_show(dev, attr, buf, wq_requested_unbound_cpumask);
7311	}
7312	static DEVICE_ATTR_RO(cpumask_requested);
7313
7314	static ssize_t cpumask_isolated_show(struct device *dev,
7315	struct device_attribute attr, char buf)
7316	{
7317	return __wq_cpumask_show(dev, attr, buf, wq_isolated_cpumask);
7318	}
7319	static DEVICE_ATTR_RO(cpumask_isolated);
7320
7321	static ssize_t cpumask_show(struct device *dev,
7322	struct device_attribute attr, char buf)
7323	{
7324	return __wq_cpumask_show(dev, attr, buf, wq_unbound_cpumask);
7325	}
7326
7327	static ssize_t cpumask_store(struct device *dev,
7328	struct device_attribute attr, const char buf, size_t count)
7329	{
7330	cpumask_var_t cpumask;
7331	int ret;
7332
7333	if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL))
7334	return -ENOMEM;
7335
7336	ret = cpumask_parse(buf, cpumask);
7337	if (!ret)
7338	ret = workqueue_set_unbound_cpumask(cpumask);
7339
7340	free_cpumask_var(cpumask);
7341	return ret ? ret : count;
7342	}
7343	static DEVICE_ATTR_RW(cpumask);
7344
7345	static struct attribute *wq_sysfs_cpumask_attrs[] = {
7346	&dev_attr_cpumask.attr,
7347	&dev_attr_cpumask_requested.attr,
7348	&dev_attr_cpumask_isolated.attr,
7349	NULL,
7350	};
7351	ATTRIBUTE_GROUPS(wq_sysfs_cpumask);
7352
7353	static int __init wq_sysfs_init(void)
7354	{
7355	return subsys_virtual_register(&wq_subsys, wq_sysfs_cpumask_groups);
7356	}
7357	core_initcall(wq_sysfs_init);
7358
7359	static void wq_device_release(struct device *dev)
7360	{
7361	struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
7362
7363	kfree(wq_dev);
7364	}
7365
7366	/**
7367	* workqueue_sysfs_register - make a workqueue visible in sysfs
7368	* @wq: the workqueue to register
7369	*
7370	* Expose @wq in sysfs under /sys/bus/workqueue/devices.
7371	* alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
7372	* which is the preferred method.
7373	*
7374	* Workqueue user should use this function directly iff it wants to apply
7375	* workqueue_attrs before making the workqueue visible in sysfs; otherwise,
7376	* apply_workqueue_attrs() may race against userland updating the
7377	* attributes.
7378	*
7379	* Return: 0 on success, -errno on failure.
7380	*/
7381	int workqueue_sysfs_register(struct workqueue_struct *wq)
7382	{
7383	struct wq_device *wq_dev;
7384	int ret;
7385
7386	/*
7387	* Adjusting max_active breaks ordering guarantee. Disallow exposing
7388	* ordered workqueues.
7389	*/
7390	if (WARN_ON(wq->flags & __WQ_ORDERED))
7391	return -EINVAL;
7392
7393	wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL);
7394	if (!wq_dev)
7395	return -ENOMEM;
7396
7397	wq_dev->wq = wq;
7398	wq_dev->dev.bus = &wq_subsys;
7399	wq_dev->dev.release = wq_device_release;
7400	dev_set_name(&wq_dev->dev, "%s", wq->name);
7401
7402	/*
7403	* unbound_attrs are created separately. Suppress uevent until
7404	* everything is ready.
7405	*/
7406	dev_set_uevent_suppress(&wq_dev->dev, true);
7407
7408	ret = device_register(&wq_dev->dev);
7409	if (ret) {
7410	put_device(&wq_dev->dev);
7411	wq->wq_dev = NULL;
7412	return ret;
7413	}
7414
7415	if (wq->flags & WQ_UNBOUND) {
7416	struct device_attribute *attr;
7417
7418	for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) {
7419	ret = device_create_file(&wq_dev->dev, attr);
7420	if (ret) {
7421	device_unregister(&wq_dev->dev);
7422	wq->wq_dev = NULL;
7423	return ret;
7424	}
7425	}
7426	}
7427
7428	dev_set_uevent_suppress(&wq_dev->dev, false);
7429	kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD);
7430	return 0;
7431	}
7432
7433	/**
7434	* workqueue_sysfs_unregister - undo workqueue_sysfs_register()
7435	* @wq: the workqueue to unregister
7436	*
7437	* If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
7438	*/
7439	static void workqueue_sysfs_unregister(struct workqueue_struct *wq)
7440	{
7441	struct wq_device *wq_dev = wq->wq_dev;
7442
7443	if (!wq->wq_dev)
7444	return;
7445
7446	wq->wq_dev = NULL;
7447	device_unregister(&wq_dev->dev);
7448	}
7449	#else /* CONFIG_SYSFS */
7450	static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { }
7451	#endif /* CONFIG_SYSFS */
7452
7453	/*
7454	* Workqueue watchdog.
7455	*
7456	* Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal
7457	* flush dependency, a concurrency managed work item which stays RUNNING
7458	* indefinitely. Workqueue stalls can be very difficult to debug as the
7459	* usual warning mechanisms don't trigger and internal workqueue state is
7460	* largely opaque.
7461	*
7462	* Workqueue watchdog monitors all worker pools periodically and dumps
7463	* state if some pools failed to make forward progress for a while where
7464	* forward progress is defined as the first item on ->worklist changing.
7465	*
7466	* This mechanism is controlled through the kernel parameter
7467	* "workqueue.watchdog_thresh" which can be updated at runtime through the
7468	* corresponding sysfs parameter file.
7469	*/
7470	#ifdef CONFIG_WQ_WATCHDOG
7471
7472	static unsigned long wq_watchdog_thresh = 30;
7473	static struct timer_list wq_watchdog_timer;
7474
7475	static unsigned long wq_watchdog_touched = INITIAL_JIFFIES;
7476	static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES;
7477
7478	static unsigned int wq_panic_on_stall;
7479	module_param_named(panic_on_stall, wq_panic_on_stall, uint, 0644);
7480
7481	/*
7482	* Show workers that might prevent the processing of pending work items.
7483	* The only candidates are CPU-bound workers in the running state.
7484	* Pending work items should be handled by another idle worker
7485	* in all other situations.
7486	*/
7487	static void show_cpu_pool_hog(struct worker_pool *pool)
7488	{
7489	struct worker *worker;
7490	unsigned long irq_flags;
7491	int bkt;
7492
7493	raw_spin_lock_irqsave(&pool->lock, irq_flags);
7494
7495	hash_for_each(pool->busy_hash, bkt, worker, hentry) {
7496	if (task_is_running(worker->task)) {
7497	/*
7498	* Defer printing to avoid deadlocks in console
7499	* drivers that queue work while holding locks
7500	* also taken in their write paths.
7501	*/
7502	printk_deferred_enter();
7503
7504	pr_info("pool %d:\n", pool->id);
7505	sched_show_task(worker->task);
7506
7507	printk_deferred_exit();
7508	}
7509	}
7510
7511	raw_spin_unlock_irqrestore(&pool->lock, irq_flags);
7512	}
7513
7514	static void show_cpu_pools_hogs(void)
7515	{
7516	struct worker_pool *pool;
7517	int pi;
7518
7519	pr_info("Showing backtraces of running workers in stalled CPU-bound worker pools:\n");
7520
7521	rcu_read_lock();
7522
7523	for_each_pool(pool, pi) {
7524	if (pool->cpu_stall)
7525	show_cpu_pool_hog(pool);
7526
7527	}
7528
7529	rcu_read_unlock();
7530	}
7531
7532	static void panic_on_wq_watchdog(void)
7533	{
7534	static unsigned int wq_stall;
7535
7536	if (wq_panic_on_stall) {
7537	wq_stall++;
7538	BUG_ON(wq_stall >= wq_panic_on_stall);
7539	}
7540	}
7541
7542	static void wq_watchdog_reset_touched(void)
7543	{
7544	int cpu;
7545
7546	wq_watchdog_touched = jiffies;
7547	for_each_possible_cpu(cpu)
7548	per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies;
7549	}
7550
7551	static void wq_watchdog_timer_fn(struct timer_list *unused)
7552	{
7553	unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ;
7554	bool lockup_detected = false;
7555	bool cpu_pool_stall = false;
7556	unsigned long now = jiffies;
7557	struct worker_pool *pool;
7558	int pi;
7559
7560	if (!thresh)
7561	return;
7562
7563	rcu_read_lock();
7564
7565	for_each_pool(pool, pi) {
7566	unsigned long pool_ts, touched, ts;
7567
7568	pool->cpu_stall = false;
7569	if (list_empty(&pool->worklist))
7570	continue;
7571
7572	/*
7573	* If a virtual machine is stopped by the host it can look to
7574	* the watchdog like a stall.
7575	*/
7576	kvm_check_and_clear_guest_paused();
7577
7578	/* get the latest of pool and touched timestamps */
7579	if (pool->cpu >= 0)
7580	touched = READ_ONCE(per_cpu(wq_watchdog_touched_cpu, pool->cpu));
7581	else
7582	touched = READ_ONCE(wq_watchdog_touched);
7583	pool_ts = READ_ONCE(pool->watchdog_ts);
7584
7585	if (time_after(pool_ts, touched))
7586	ts = pool_ts;
7587	else
7588	ts = touched;
7589
7590	/* did we stall? */
7591	if (time_after(now, ts + thresh)) {
7592	lockup_detected = true;
7593	if (pool->cpu >= 0 && !(pool->flags & POOL_BH)) {
7594	pool->cpu_stall = true;
7595	cpu_pool_stall = true;
7596	}
7597	pr_emerg("BUG: workqueue lockup - pool");
7598	pr_cont_pool_info(pool);
7599	pr_cont(" stuck for %us!\n",
7600	jiffies_to_msecs(now - pool_ts) / 1000);
7601	}
7602
7603
7604	}
7605
7606	rcu_read_unlock();
7607
7608	if (lockup_detected)
7609	show_all_workqueues();
7610
7611	if (cpu_pool_stall)
7612	show_cpu_pools_hogs();
7613
7614	if (lockup_detected)
7615	panic_on_wq_watchdog();
7616
7617	wq_watchdog_reset_touched();
7618	mod_timer(&wq_watchdog_timer, jiffies + thresh);
7619	}
7620
7621	notrace void wq_watchdog_touch(int cpu)
7622	{
7623	unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ;
7624	unsigned long touch_ts = READ_ONCE(wq_watchdog_touched);
7625	unsigned long now = jiffies;
7626
7627	if (cpu >= 0)
7628	per_cpu(wq_watchdog_touched_cpu, cpu) = now;
7629	else
7630	WARN_ONCE(1, "%s should be called with valid CPU", __func__);
7631
7632	/* Don't unnecessarily store to global cacheline */
7633	if (time_after(now, touch_ts + thresh / 4))
7634	WRITE_ONCE(wq_watchdog_touched, jiffies);
7635	}
7636
7637	static void wq_watchdog_set_thresh(unsigned long thresh)
7638	{
7639	wq_watchdog_thresh = 0;
7640	timer_delete_sync(&wq_watchdog_timer);
7641
7642	if (thresh) {
7643	wq_watchdog_thresh = thresh;
7644	wq_watchdog_reset_touched();
7645	mod_timer(&wq_watchdog_timer, jiffies + thresh * HZ);
7646	}
7647	}
7648
7649	static int wq_watchdog_param_set_thresh(const char *val,
7650	const struct kernel_param *kp)
7651	{
7652	unsigned long thresh;
7653	int ret;
7654
7655	ret = kstrtoul(val, 0, &thresh);
7656	if (ret)
7657	return ret;
7658
7659	if (system_wq)
7660	wq_watchdog_set_thresh(thresh);
7661	else
7662	wq_watchdog_thresh = thresh;
7663
7664	return 0;
7665	}
7666
7667	static const struct kernel_param_ops wq_watchdog_thresh_ops = {
7668	.set = wq_watchdog_param_set_thresh,
7669	.get = param_get_ulong,
7670	};
7671
7672	module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh,
7673	0644);
7674
7675	static void wq_watchdog_init(void)
7676	{
7677	timer_setup(&wq_watchdog_timer, wq_watchdog_timer_fn, TIMER_DEFERRABLE);
7678	wq_watchdog_set_thresh(wq_watchdog_thresh);
7679	}
7680
7681	#else /* CONFIG_WQ_WATCHDOG */
7682
7683	static inline void wq_watchdog_init(void) { }
7684
7685	#endif /* CONFIG_WQ_WATCHDOG */
7686
7687	static void bh_pool_kick_normal(struct irq_work *irq_work)
7688	{
7689	raise_softirq_irqoff(TASKLET_SOFTIRQ);
7690	}
7691
7692	static void bh_pool_kick_highpri(struct irq_work *irq_work)
7693	{
7694	raise_softirq_irqoff(HI_SOFTIRQ);
7695	}
7696
7697	static void __init restrict_unbound_cpumask(const char name, const struct cpumask mask)
7698	{
7699	if (!cpumask_intersects(wq_unbound_cpumask, mask)) {
7700	pr_warn("workqueue: Restricting unbound_cpumask (%pb) with %s (%pb) leaves no CPU, ignoring\n",
7701	cpumask_pr_args(wq_unbound_cpumask), name, cpumask_pr_args(mask));
7702	return;
7703	}
7704
7705	cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, mask);
7706	}
7707
7708	static void __init init_cpu_worker_pool(struct worker_pool *pool, int cpu, int nice)
7709	{
7710	BUG_ON(init_worker_pool(pool));
7711	pool->cpu = cpu;
7712	cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu));
7713	cpumask_copy(pool->attrs->__pod_cpumask, cpumask_of(cpu));
7714	pool->attrs->nice = nice;
7715	pool->attrs->affn_strict = true;
7716	pool->node = cpu_to_node(cpu);
7717
7718	/* alloc pool ID */
7719	mutex_lock(&wq_pool_mutex);
7720	BUG_ON(worker_pool_assign_id(pool));
7721	mutex_unlock(&wq_pool_mutex);
7722	}
7723
7724	/**
7725	* workqueue_init_early - early init for workqueue subsystem
7726	*
7727	* This is the first step of three-staged workqueue subsystem initialization and
7728	* invoked as soon as the bare basics - memory allocation, cpumasks and idr are
7729	* up. It sets up all the data structures and system workqueues and allows early
7730	* boot code to create workqueues and queue/cancel work items. Actual work item
7731	* execution starts only after kthreads can be created and scheduled right
7732	* before early initcalls.
7733	*/
7734	void __init workqueue_init_early(void)
7735	{
7736	struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_SYSTEM];
7737	int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL };
7738	void (irq_work_fns[2])(struct irq_work ) = { bh_pool_kick_normal,
7739	bh_pool_kick_highpri };
7740	int i, cpu;
7741
7742	BUILD_BUG_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
7743
7744	BUG_ON(!alloc_cpumask_var(&wq_online_cpumask, GFP_KERNEL));
7745	BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL));
7746	BUG_ON(!alloc_cpumask_var(&wq_requested_unbound_cpumask, GFP_KERNEL));
7747	BUG_ON(!zalloc_cpumask_var(&wq_isolated_cpumask, GFP_KERNEL));
7748
7749	cpumask_copy(wq_online_cpumask, cpu_online_mask);
7750	cpumask_copy(wq_unbound_cpumask, cpu_possible_mask);
7751	restrict_unbound_cpumask("HK_TYPE_WQ", housekeeping_cpumask(HK_TYPE_WQ));
7752	restrict_unbound_cpumask("HK_TYPE_DOMAIN", housekeeping_cpumask(HK_TYPE_DOMAIN));
7753	if (!cpumask_empty(&wq_cmdline_cpumask))
7754	restrict_unbound_cpumask("workqueue.unbound_cpus", &wq_cmdline_cpumask);
7755
7756	cpumask_copy(wq_requested_unbound_cpumask, wq_unbound_cpumask);
7757
7758	pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);
7759
7760	unbound_wq_update_pwq_attrs_buf = alloc_workqueue_attrs();
7761	BUG_ON(!unbound_wq_update_pwq_attrs_buf);
7762
7763	/*
7764	* If nohz_full is enabled, set power efficient workqueue as unbound.
7765	* This allows workqueue items to be moved to HK CPUs.
7766	*/
7767	if (housekeeping_enabled(HK_TYPE_TICK))
7768	wq_power_efficient = true;
7769
7770	/* initialize WQ_AFFN_SYSTEM pods */
7771	pt->pod_cpus = kcalloc(1, sizeof(pt->pod_cpus[0]), GFP_KERNEL);
7772	pt->pod_node = kcalloc(1, sizeof(pt->pod_node[0]), GFP_KERNEL);
7773	pt->cpu_pod = kcalloc(nr_cpu_ids, sizeof(pt->cpu_pod[0]), GFP_KERNEL);
7774	BUG_ON(!pt->pod_cpus \|\| !pt->pod_node \|\| !pt->cpu_pod);
7775
7776	BUG_ON(!zalloc_cpumask_var_node(&pt->pod_cpus[0], GFP_KERNEL, NUMA_NO_NODE));
7777
7778	pt->nr_pods = 1;
7779	cpumask_copy(pt->pod_cpus[0], cpu_possible_mask);
7780	pt->pod_node[0] = NUMA_NO_NODE;
7781	pt->cpu_pod[0] = 0;
7782
7783	/* initialize BH and CPU pools */
7784	for_each_possible_cpu(cpu) {
7785	struct worker_pool *pool;
7786
7787	i = 0;
7788	for_each_bh_worker_pool(pool, cpu) {
7789	init_cpu_worker_pool(pool, cpu, std_nice[i]);
7790	pool->flags \|= POOL_BH;
7791	init_irq_work(bh_pool_irq_work(pool), irq_work_fns[i]);
7792	i++;
7793	}
7794
7795	i = 0;
7796	for_each_cpu_worker_pool(pool, cpu)
7797	init_cpu_worker_pool(pool, cpu, std_nice[i++]);
7798	}
7799
7800	/* create default unbound and ordered wq attrs */
7801	for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
7802	struct workqueue_attrs *attrs;
7803
7804	BUG_ON(!(attrs = alloc_workqueue_attrs()));
7805	attrs->nice = std_nice[i];
7806	unbound_std_wq_attrs[i] = attrs;
7807
7808	/*
7809	* An ordered wq should have only one pwq as ordering is
7810	* guaranteed by max_active which is enforced by pwqs.
7811	*/
7812	BUG_ON(!(attrs = alloc_workqueue_attrs()));
7813	attrs->nice = std_nice[i];
7814	attrs->ordered = true;
7815	ordered_wq_attrs[i] = attrs;
7816	}
7817
7818	system_wq = alloc_workqueue("events", 0, 0);
7819	system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0);
7820	system_long_wq = alloc_workqueue("events_long", 0, 0);
7821	system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
7822	WQ_MAX_ACTIVE);
7823	system_freezable_wq = alloc_workqueue("events_freezable",
7824	WQ_FREEZABLE, 0);
7825	system_power_efficient_wq = alloc_workqueue("events_power_efficient",
7826	WQ_POWER_EFFICIENT, 0);
7827	system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_pwr_efficient",
7828	WQ_FREEZABLE \| WQ_POWER_EFFICIENT,
7829	0);
7830	system_bh_wq = alloc_workqueue("events_bh", WQ_BH, 0);
7831	system_bh_highpri_wq = alloc_workqueue("events_bh_highpri",
7832	WQ_BH \| WQ_HIGHPRI, 0);
7833	BUG_ON(!system_wq \|\| !system_highpri_wq \|\| !system_long_wq \|\|
7834	!system_unbound_wq \|\| !system_freezable_wq \|\|
7835	!system_power_efficient_wq \|\|
7836	!system_freezable_power_efficient_wq \|\|
7837	!system_bh_wq \|\| !system_bh_highpri_wq);
7838	}
7839
7840	static void __init wq_cpu_intensive_thresh_init(void)
7841	{
7842	unsigned long thresh;
7843	unsigned long bogo;
7844
7845	pwq_release_worker = kthread_run_worker(0, "pool_workqueue_release");
7846	BUG_ON(IS_ERR(pwq_release_worker));
7847
7848	/* if the user set it to a specific value, keep it */
7849	if (wq_cpu_intensive_thresh_us != ULONG_MAX)
7850	return;
7851
7852	/*
7853	* The default of 10ms is derived from the fact that most modern (as of
7854	* 2023) processors can do a lot in 10ms and that it's just below what
7855	* most consider human-perceivable. However, the kernel also runs on a
7856	* lot slower CPUs including microcontrollers where the threshold is way
7857	* too low.
7858	*
7859	* Let's scale up the threshold upto 1 second if BogoMips is below 4000.
7860	* This is by no means accurate but it doesn't have to be. The mechanism
7861	* is still useful even when the threshold is fully scaled up. Also, as
7862	* the reports would usually be applicable to everyone, some machines
7863	* operating on longer thresholds won't significantly diminish their
7864	* usefulness.
7865	*/
7866	thresh = 10 * USEC_PER_MSEC;
7867
7868	/* see init/calibrate.c for lpj -> BogoMIPS calculation */
7869	bogo = max_t(unsigned long, loops_per_jiffy / 500000 * HZ, 1);
7870	if (bogo < 4000)
7871	thresh = min_t(unsigned long, thresh * 4000 / bogo, USEC_PER_SEC);
7872
7873	pr_debug("wq_cpu_intensive_thresh: lpj=%lu BogoMIPS=%lu thresh_us=%lu\n",
7874	loops_per_jiffy, bogo, thresh);
7875
7876	wq_cpu_intensive_thresh_us = thresh;
7877	}
7878
7879	/**
7880	* workqueue_init - bring workqueue subsystem fully online
7881	*
7882	* This is the second step of three-staged workqueue subsystem initialization
7883	* and invoked as soon as kthreads can be created and scheduled. Workqueues have
7884	* been created and work items queued on them, but there are no kworkers
7885	* executing the work items yet. Populate the worker pools with the initial
7886	* workers and enable future kworker creations.
7887	*/
7888	void __init workqueue_init(void)
7889	{
7890	struct workqueue_struct *wq;
7891	struct worker_pool *pool;
7892	int cpu, bkt;
7893
7894	wq_cpu_intensive_thresh_init();
7895
7896	mutex_lock(&wq_pool_mutex);
7897
7898	/*
7899	* Per-cpu pools created earlier could be missing node hint. Fix them
7900	* up. Also, create a rescuer for workqueues that requested it.
7901	*/
7902	for_each_possible_cpu(cpu) {
7903	for_each_bh_worker_pool(pool, cpu)
7904	pool->node = cpu_to_node(cpu);
7905	for_each_cpu_worker_pool(pool, cpu)
7906	pool->node = cpu_to_node(cpu);
7907	}
7908
7909	list_for_each_entry(wq, &workqueues, list) {
7910	WARN(init_rescuer(wq),
7911	"workqueue: failed to create early rescuer for %s",
7912	wq->name);
7913	}
7914
7915	mutex_unlock(&wq_pool_mutex);
7916
7917	/*
7918	* Create the initial workers. A BH pool has one pseudo worker that
7919	* represents the shared BH execution context and thus doesn't get
7920	* affected by hotplug events. Create the BH pseudo workers for all
7921	* possible CPUs here.
7922	*/
7923	for_each_possible_cpu(cpu)
7924	for_each_bh_worker_pool(pool, cpu)
7925	BUG_ON(!create_worker(pool));
7926
7927	for_each_online_cpu(cpu) {
7928	for_each_cpu_worker_pool(pool, cpu) {
7929	pool->flags &= ~POOL_DISASSOCIATED;
7930	BUG_ON(!create_worker(pool));
7931	}
7932	}
7933
7934	hash_for_each(unbound_pool_hash, bkt, pool, hash_node)
7935	BUG_ON(!create_worker(pool));
7936
7937	wq_online = true;
7938	wq_watchdog_init();
7939	}
7940
7941	/*
7942	* Initialize @pt by first initializing @pt->cpu_pod[] with pod IDs according to
7943	* @cpu_shares_pod(). Each subset of CPUs that share a pod is assigned a unique
7944	* and consecutive pod ID. The rest of @pt is initialized accordingly.
7945	*/
7946	static void __init init_pod_type(struct wq_pod_type *pt,
7947	bool (*cpus_share_pod)(int, int))
7948	{
7949	int cur, pre, cpu, pod;
7950
7951	pt->nr_pods = 0;
7952
7953	/* init @pt->cpu_pod[] according to @cpus_share_pod() */
7954	pt->cpu_pod = kcalloc(nr_cpu_ids, sizeof(pt->cpu_pod[0]), GFP_KERNEL);
7955	BUG_ON(!pt->cpu_pod);
7956
7957	for_each_possible_cpu(cur) {
7958	for_each_possible_cpu(pre) {
7959	if (pre >= cur) {
7960	pt->cpu_pod[cur] = pt->nr_pods++;
7961	break;
7962	}
7963	if (cpus_share_pod(cur, pre)) {
7964	pt->cpu_pod[cur] = pt->cpu_pod[pre];
7965	break;
7966	}
7967	}
7968	}
7969
7970	/* init the rest to match @pt->cpu_pod[] */
7971	pt->pod_cpus = kcalloc(pt->nr_pods, sizeof(pt->pod_cpus[0]), GFP_KERNEL);
7972	pt->pod_node = kcalloc(pt->nr_pods, sizeof(pt->pod_node[0]), GFP_KERNEL);
7973	BUG_ON(!pt->pod_cpus \|\| !pt->pod_node);
7974
7975	for (pod = 0; pod < pt->nr_pods; pod++)
7976	BUG_ON(!zalloc_cpumask_var(&pt->pod_cpus[pod], GFP_KERNEL));
7977
7978	for_each_possible_cpu(cpu) {
7979	cpumask_set_cpu(cpu, pt->pod_cpus[pt->cpu_pod[cpu]]);
7980	pt->pod_node[pt->cpu_pod[cpu]] = cpu_to_node(cpu);
7981	}
7982	}
7983
7984	static bool __init cpus_dont_share(int cpu0, int cpu1)
7985	{
7986	return false;
7987	}
7988
7989	static bool __init cpus_share_smt(int cpu0, int cpu1)
7990	{
7991	#ifdef CONFIG_SCHED_SMT
7992	return cpumask_test_cpu(cpu0, cpu_smt_mask(cpu1));
7993	#else
7994	return false;
7995	#endif
7996	}
7997
7998	static bool __init cpus_share_numa(int cpu0, int cpu1)
7999	{
8000	return cpu_to_node(cpu0) == cpu_to_node(cpu1);
8001	}
8002
8003	/**
8004	* workqueue_init_topology - initialize CPU pods for unbound workqueues
8005	*
8006	* This is the third step of three-staged workqueue subsystem initialization and
8007	* invoked after SMP and topology information are fully initialized. It
8008	* initializes the unbound CPU pods accordingly.
8009	*/
8010	void __init workqueue_init_topology(void)
8011	{
8012	struct workqueue_struct *wq;
8013	int cpu;
8014
8015	init_pod_type(&wq_pod_types[WQ_AFFN_CPU], cpus_dont_share);
8016	init_pod_type(&wq_pod_types[WQ_AFFN_SMT], cpus_share_smt);
8017	init_pod_type(&wq_pod_types[WQ_AFFN_CACHE], cpus_share_cache);
8018	init_pod_type(&wq_pod_types[WQ_AFFN_NUMA], cpus_share_numa);
8019
8020	wq_topo_initialized = true;
8021
8022	mutex_lock(&wq_pool_mutex);
8023
8024	/*
8025	* Workqueues allocated earlier would have all CPUs sharing the default
8026	* worker pool. Explicitly call unbound_wq_update_pwq() on all workqueue
8027	* and CPU combinations to apply per-pod sharing.
8028	*/
8029	list_for_each_entry(wq, &workqueues, list) {
8030	for_each_online_cpu(cpu)
8031	unbound_wq_update_pwq(wq, cpu);
8032	if (wq->flags & WQ_UNBOUND) {
8033	mutex_lock(&wq->mutex);
8034	wq_update_node_max_active(wq, -1);
8035	mutex_unlock(&wq->mutex);
8036	}
8037	}
8038
8039	mutex_unlock(&wq_pool_mutex);
8040	}
8041
8042	void __warn_flushing_systemwide_wq(void)
8043	{
8044	pr_warn("WARNING: Flushing system-wide workqueues will be prohibited in near future.\n");
8045	dump_stack();
8046	}
8047	EXPORT_SYMBOL(__warn_flushing_systemwide_wq);
8048
8049	static int __init workqueue_unbound_cpus_setup(char *str)
8050	{
8051	if (cpulist_parse(str, &wq_cmdline_cpumask) < 0) {
8052	cpumask_clear(&wq_cmdline_cpumask);
8053	pr_warn("workqueue.unbound_cpus: incorrect CPU range, using default\n");
8054	}
8055
8056	return 1;
8057	}
8058	__setup("workqueue.unbound_cpus=", workqueue_unbound_cpus_setup);