linux - kernel/workqueue.c

6828 lines · 189.4 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/signal.h>
33	#include <linux/completion.h>
34	#include <linux/workqueue.h>
35	#include <linux/slab.h>
36	#include <linux/cpu.h>
37	#include <linux/notifier.h>
38	#include <linux/kthread.h>
39	#include <linux/hardirq.h>
40	#include <linux/mempolicy.h>
41	#include <linux/freezer.h>
42	#include <linux/debug_locks.h>
43	#include <linux/lockdep.h>
44	#include <linux/idr.h>
45	#include <linux/jhash.h>
46	#include <linux/hashtable.h>
47	#include <linux/rculist.h>
48	#include <linux/nodemask.h>
49	#include <linux/moduleparam.h>
50	#include <linux/uaccess.h>
51	#include <linux/sched/isolation.h>
52	#include <linux/sched/debug.h>
53	#include <linux/nmi.h>
54	#include <linux/kvm_para.h>
55	#include <linux/delay.h>
56
57	#include "workqueue_internal.h"
58
59	enum {
60	/*
61	* worker_pool flags
62	*
63	* A bound pool is either associated or disassociated with its CPU.
64	* While associated (!DISASSOCIATED), all workers are bound to the
65	* CPU and none has %WORKER_UNBOUND set and concurrency management
66	* is in effect.
67	*
68	* While DISASSOCIATED, the cpu may be offline and all workers have
69	* %WORKER_UNBOUND set and concurrency management disabled, and may
70	* be executing on any CPU. The pool behaves as an unbound one.
71	*
72	* Note that DISASSOCIATED should be flipped only while holding
73	* wq_pool_attach_mutex to avoid changing binding state while
74	* worker_attach_to_pool() is in progress.
75	*/
76	POOL_MANAGER_ACTIVE = 1 << 0, /* being managed */
77	POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
78
79	/* worker flags */
80	WORKER_DIE = 1 << 1, /* die die die */
81	WORKER_IDLE = 1 << 2, /* is idle */
82	WORKER_PREP = 1 << 3, /* preparing to run works */
83	WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
84	WORKER_UNBOUND = 1 << 7, /* worker is unbound */
85	WORKER_REBOUND = 1 << 8, /* worker was rebound */
86
87	WORKER_NOT_RUNNING = WORKER_PREP \| WORKER_CPU_INTENSIVE \|
88	WORKER_UNBOUND \| WORKER_REBOUND,
89
90	NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */
91
92	UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */
93	BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
94
95	MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
96	IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
97
98	MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2,
99	/* call for help after 10ms
100	(min two ticks) */
101	MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
102	CREATE_COOLDOWN = HZ, /* time to breath after fail */
103
104	/*
105	* Rescue workers are used only on emergencies and shared by
106	* all cpus. Give MIN_NICE.
107	*/
108	RESCUER_NICE_LEVEL = MIN_NICE,
109	HIGHPRI_NICE_LEVEL = MIN_NICE,
110
111	WQ_NAME_LEN = 24,
112	};
113
114	/*
115	* Structure fields follow one of the following exclusion rules.
116	*
117	* I: Modifiable by initialization/destruction paths and read-only for
118	* everyone else.
119	*
120	* P: Preemption protected. Disabling preemption is enough and should
121	* only be modified and accessed from the local cpu.
122	*
123	* L: pool->lock protected. Access with pool->lock held.
124	*
125	* K: Only modified by worker while holding pool->lock. Can be safely read by
126	* self, while holding pool->lock or from IRQ context if %current is the
127	* kworker.
128	*
129	* S: Only modified by worker self.
130	*
131	* A: wq_pool_attach_mutex protected.
132	*
133	* PL: wq_pool_mutex protected.
134	*
135	* PR: wq_pool_mutex protected for writes. RCU protected for reads.
136	*
137	* PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads.
138	*
139	* PWR: wq_pool_mutex and wq->mutex protected for writes. Either or
140	* RCU for reads.
141	*
142	* WQ: wq->mutex protected.
143	*
144	* WR: wq->mutex protected for writes. RCU protected for reads.
145	*
146	* MD: wq_mayday_lock protected.
147	*
148	* WD: Used internally by the watchdog.
149	*/
150
151	/* struct worker is defined in workqueue_internal.h */
152
153	struct worker_pool {
154	raw_spinlock_t lock; /* the pool lock */
155	int cpu; /* I: the associated cpu */
156	int node; /* I: the associated node ID */
157	int id; /* I: pool ID */
158	unsigned int flags; /* L: flags */
159
160	unsigned long watchdog_ts; /* L: watchdog timestamp */
161	bool cpu_stall; /* WD: stalled cpu bound pool */
162
163	/*
164	* The counter is incremented in a process context on the associated CPU
165	* w/ preemption disabled, and decremented or reset in the same context
166	* but w/ pool->lock held. The readers grab pool->lock and are
167	* guaranteed to see if the counter reached zero.
168	*/
169	int nr_running;
170
171	struct list_head worklist; /* L: list of pending works */
172
173	int nr_workers; /* L: total number of workers */
174	int nr_idle; /* L: currently idle workers */
175
176	struct list_head idle_list; /* L: list of idle workers */
177	struct timer_list idle_timer; /* L: worker idle timeout */
178	struct work_struct idle_cull_work; /* L: worker idle cleanup */
179
180	struct timer_list mayday_timer; /* L: SOS timer for workers */
181
182	/* a workers is either on busy_hash or idle_list, or the manager */
183	DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
184	/* L: hash of busy workers */
185
186	struct worker manager; / L: purely informational */
187	struct list_head workers; /* A: attached workers */
188	struct list_head dying_workers; /* A: workers about to die */
189	struct completion detach_completion; / all workers detached */
190
191	struct ida worker_ida; /* worker IDs for task name */
192
193	struct workqueue_attrs attrs; / I: worker attributes */
194	struct hlist_node hash_node; /* PL: unbound_pool_hash node */
195	int refcnt; /* PL: refcnt for unbound pools */
196
197	/*
198	* Destruction of pool is RCU protected to allow dereferences
199	* from get_work_pool().
200	*/
201	struct rcu_head rcu;
202	};
203
204	/*
205	* Per-pool_workqueue statistics. These can be monitored using
206	* tools/workqueue/wq_monitor.py.
207	*/
208	enum pool_workqueue_stats {
209	PWQ_STAT_STARTED, /* work items started execution */
210	PWQ_STAT_COMPLETED, /* work items completed execution */
211	PWQ_STAT_CPU_TIME, /* total CPU time consumed */
212	PWQ_STAT_CPU_INTENSIVE, /* wq_cpu_intensive_thresh_us violations */
213	PWQ_STAT_CM_WAKEUP, /* concurrency-management worker wakeups */
214	PWQ_STAT_REPATRIATED, /* unbound workers brought back into scope */
215	PWQ_STAT_MAYDAY, /* maydays to rescuer */
216	PWQ_STAT_RESCUED, /* linked work items executed by rescuer */
217
218	PWQ_NR_STATS,
219	};
220
221	/*
222	* The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
223	* of work_struct->data are used for flags and the remaining high bits
224	* point to the pwq; thus, pwqs need to be aligned at two's power of the
225	* number of flag bits.
226	*/
227	struct pool_workqueue {
228	struct worker_pool pool; / I: the associated pool */
229	struct workqueue_struct wq; / I: the owning workqueue */
230	int work_color; /* L: current color */
231	int flush_color; /* L: flushing color */
232	int refcnt; /* L: reference count */
233	int nr_in_flight[WORK_NR_COLORS];
234	/* L: nr of in_flight works */
235
236	/*
237	* nr_active management and WORK_STRUCT_INACTIVE:
238	*
239	* When pwq->nr_active >= max_active, new work item is queued to
240	* pwq->inactive_works instead of pool->worklist and marked with
241	* WORK_STRUCT_INACTIVE.
242	*
243	* All work items marked with WORK_STRUCT_INACTIVE do not participate
244	* in pwq->nr_active and all work items in pwq->inactive_works are
245	* marked with WORK_STRUCT_INACTIVE. But not all WORK_STRUCT_INACTIVE
246	* work items are in pwq->inactive_works. Some of them are ready to
247	* run in pool->worklist or worker->scheduled. Those work itmes are
248	* only struct wq_barrier which is used for flush_work() and should
249	* not participate in pwq->nr_active. For non-barrier work item, it
250	* is marked with WORK_STRUCT_INACTIVE iff it is in pwq->inactive_works.
251	*/
252	int nr_active; /* L: nr of active works */
253	int max_active; /* L: max active works */
254	struct list_head inactive_works; /* L: inactive works */
255	struct list_head pwqs_node; /* WR: node on wq->pwqs */
256	struct list_head mayday_node; /* MD: node on wq->maydays */
257
258	u64 stats[PWQ_NR_STATS];
259
260	/*
261	* Release of unbound pwq is punted to a kthread_worker. See put_pwq()
262	* and pwq_release_workfn() for details. pool_workqueue itself is also
263	* RCU protected so that the first pwq can be determined without
264	* grabbing wq->mutex.
265	*/
266	struct kthread_work release_work;
267	struct rcu_head rcu;
268	} __aligned(1 << WORK_STRUCT_FLAG_BITS);
269
270	/*
271	* Structure used to wait for workqueue flush.
272	*/
273	struct wq_flusher {
274	struct list_head list; /* WQ: list of flushers */
275	int flush_color; /* WQ: flush color waiting for */
276	struct completion done; /* flush completion */
277	};
278
279	struct wq_device;
280
281	/*
282	* The externally visible workqueue. It relays the issued work items to
283	* the appropriate worker_pool through its pool_workqueues.
284	*/
285	struct workqueue_struct {
286	struct list_head pwqs; /* WR: all pwqs of this wq */
287	struct list_head list; /* PR: list of all workqueues */
288
289	struct mutex mutex; /* protects this wq */
290	int work_color; /* WQ: current work color */
291	int flush_color; /* WQ: current flush color */
292	atomic_t nr_pwqs_to_flush; /* flush in progress */
293	struct wq_flusher first_flusher; / WQ: first flusher */
294	struct list_head flusher_queue; /* WQ: flush waiters */
295	struct list_head flusher_overflow; /* WQ: flush overflow list */
296
297	struct list_head maydays; /* MD: pwqs requesting rescue */
298	struct worker rescuer; / MD: rescue worker */
299
300	int nr_drainers; /* WQ: drain in progress */
301	int saved_max_active; /* WQ: saved pwq max_active */
302
303	struct workqueue_attrs unbound_attrs; / PW: only for unbound wqs */
304	struct pool_workqueue dfl_pwq; / PW: only for unbound wqs */
305
306	#ifdef CONFIG_SYSFS
307	struct wq_device wq_dev; / I: for sysfs interface */
308	#endif
309	#ifdef CONFIG_LOCKDEP
310	char *lock_name;
311	struct lock_class_key key;
312	struct lockdep_map lockdep_map;
313	#endif
314	char name[WQ_NAME_LEN]; /* I: workqueue name */
315
316	/*
317	* Destruction of workqueue_struct is RCU protected to allow walking
318	* the workqueues list without grabbing wq_pool_mutex.
319	* This is used to dump all workqueues from sysrq.
320	*/
321	struct rcu_head rcu;
322
323	/* hot fields used during command issue, aligned to cacheline */
324	unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */
325	struct pool_workqueue __percpu __rcu *cpu_pwq; / I: per-cpu pwqs */
326	};
327
328	static struct kmem_cache *pwq_cache;
329
330	/*
331	* Each pod type describes how CPUs should be grouped for unbound workqueues.
332	* See the comment above workqueue_attrs->affn_scope.
333	*/
334	struct wq_pod_type {
335	int nr_pods; /* number of pods */
336	cpumask_var_t pod_cpus; / pod -> cpus */
337	int pod_node; / pod -> node */
338	int cpu_pod; / cpu -> pod */
339	};
340
341	static struct wq_pod_type wq_pod_types[WQ_AFFN_NR_TYPES];
342	static enum wq_affn_scope wq_affn_dfl = WQ_AFFN_CACHE;
343
344	static const char *wq_affn_names[WQ_AFFN_NR_TYPES] = {
345	[WQ_AFFN_DFL] = "default",
346	[WQ_AFFN_CPU] = "cpu",
347	[WQ_AFFN_SMT] = "smt",
348	[WQ_AFFN_CACHE] = "cache",
349	[WQ_AFFN_NUMA] = "numa",
350	[WQ_AFFN_SYSTEM] = "system",
351	};
352
353	/*
354	* Per-cpu work items which run for longer than the following threshold are
355	* automatically considered CPU intensive and excluded from concurrency
356	* management to prevent them from noticeably delaying other per-cpu work items.
357	* ULONG_MAX indicates that the user hasn't overridden it with a boot parameter.
358	* The actual value is initialized in wq_cpu_intensive_thresh_init().
359	*/
360	static unsigned long wq_cpu_intensive_thresh_us = ULONG_MAX;
361	module_param_named(cpu_intensive_thresh_us, wq_cpu_intensive_thresh_us, ulong, 0644);
362
363	/* see the comment above the definition of WQ_POWER_EFFICIENT */
364	static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT);
365	module_param_named(power_efficient, wq_power_efficient, bool, 0444);
366
367	static bool wq_online; /* can kworkers be created yet? */
368
369	/* buf for wq_update_unbound_pod_attrs(), protected by CPU hotplug exclusion */
370	static struct workqueue_attrs *wq_update_pod_attrs_buf;
371
372	static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */
373	static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */
374	static DEFINE_RAW_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
375	/* wait for manager to go away */
376	static struct rcuwait manager_wait = __RCUWAIT_INITIALIZER(manager_wait);
377
378	static LIST_HEAD(workqueues); /* PR: list of all workqueues */
379	static bool workqueue_freezing; /* PL: have wqs started freezing? */
380
381	/* PL&A: allowable cpus for unbound wqs and work items */
382	static cpumask_var_t wq_unbound_cpumask;
383
384	/* for further constrain wq_unbound_cpumask by cmdline parameter*/
385	static struct cpumask wq_cmdline_cpumask __initdata;
386
387	/* CPU where unbound work was last round robin scheduled from this CPU */
388	static DEFINE_PER_CPU(int, wq_rr_cpu_last);
389
390	/*
391	* Local execution of unbound work items is no longer guaranteed. The
392	* following always forces round-robin CPU selection on unbound work items
393	* to uncover usages which depend on it.
394	*/
395	#ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU
396	static bool wq_debug_force_rr_cpu = true;
397	#else
398	static bool wq_debug_force_rr_cpu = false;
399	#endif
400	module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644);
401
402	/* the per-cpu worker pools */
403	static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools);
404
405	static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */
406
407	/* PL: hash of all unbound pools keyed by pool->attrs */
408	static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER);
409
410	/* I: attributes used when instantiating standard unbound pools on demand */
411	static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS];
412
413	/* I: attributes used when instantiating ordered pools on demand */
414	static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS];
415
416	/*
417	* I: kthread_worker to release pwq's. pwq release needs to be bounced to a
418	* process context while holding a pool lock. Bounce to a dedicated kthread
419	* worker to avoid A-A deadlocks.
420	*/
421	static struct kthread_worker *pwq_release_worker __ro_after_init;
422
423	struct workqueue_struct *system_wq __ro_after_init;
424	EXPORT_SYMBOL(system_wq);
425	struct workqueue_struct *system_highpri_wq __ro_after_init;
426	EXPORT_SYMBOL_GPL(system_highpri_wq);
427	struct workqueue_struct *system_long_wq __ro_after_init;
428	EXPORT_SYMBOL_GPL(system_long_wq);
429	struct workqueue_struct *system_unbound_wq __ro_after_init;
430	EXPORT_SYMBOL_GPL(system_unbound_wq);
431	struct workqueue_struct *system_freezable_wq __ro_after_init;
432	EXPORT_SYMBOL_GPL(system_freezable_wq);
433	struct workqueue_struct *system_power_efficient_wq __ro_after_init;
434	EXPORT_SYMBOL_GPL(system_power_efficient_wq);
435	struct workqueue_struct *system_freezable_power_efficient_wq __ro_after_init;
436	EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq);
437
438	static int worker_thread(void *__worker);
439	static void workqueue_sysfs_unregister(struct workqueue_struct *wq);
440	static void show_pwq(struct pool_workqueue *pwq);
441	static void show_one_worker_pool(struct worker_pool *pool);
442
443	#define CREATE_TRACE_POINTS
444	#include <trace/events/workqueue.h>
445
446	#define assert_rcu_or_pool_mutex() \
447	RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
448	!lockdep_is_held(&wq_pool_mutex), \
449	"RCU or wq_pool_mutex should be held")
450
451	#define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \
452	RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
453	!lockdep_is_held(&wq->mutex) && \
454	!lockdep_is_held(&wq_pool_mutex), \
455	"RCU, wq->mutex or wq_pool_mutex should be held")
456
457	#define for_each_cpu_worker_pool(pool, cpu) \
458	for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
459	(pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
460	(pool)++)
461
462	/**
463	* for_each_pool - iterate through all worker_pools in the system
464	* @pool: iteration cursor
465	* @pi: integer used for iteration
466	*
467	* This must be called either with wq_pool_mutex held or RCU read
468	* locked. If the pool needs to be used beyond the locking in effect, the
469	* caller is responsible for guaranteeing that the pool stays online.
470	*
471	* The if/else clause exists only for the lockdep assertion and can be
472	* ignored.
473	*/
474	#define for_each_pool(pool, pi) \
475	idr_for_each_entry(&worker_pool_idr, pool, pi) \
476	if (({ assert_rcu_or_pool_mutex(); false; })) { } \
477	else
478
479	/**
480	* for_each_pool_worker - iterate through all workers of a worker_pool
481	* @worker: iteration cursor
482	* @pool: worker_pool to iterate workers of
483	*
484	* This must be called with wq_pool_attach_mutex.
485	*
486	* The if/else clause exists only for the lockdep assertion and can be
487	* ignored.
488	*/
489	#define for_each_pool_worker(worker, pool) \
490	list_for_each_entry((worker), &(pool)->workers, node) \
491	if (({ lockdep_assert_held(&wq_pool_attach_mutex); false; })) { } \
492	else
493
494	/**
495	* for_each_pwq - iterate through all pool_workqueues of the specified workqueue
496	* @pwq: iteration cursor
497	* @wq: the target workqueue
498	*
499	* This must be called either with wq->mutex held or RCU read locked.
500	* If the pwq needs to be used beyond the locking in effect, the caller is
501	* responsible for guaranteeing that the pwq stays online.
502	*
503	* The if/else clause exists only for the lockdep assertion and can be
504	* ignored.
505	*/
506	#define for_each_pwq(pwq, wq) \
507	list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node, \
508	lockdep_is_held(&(wq->mutex)))
509
510	#ifdef CONFIG_DEBUG_OBJECTS_WORK
511
512	static const struct debug_obj_descr work_debug_descr;
513
514	static void work_debug_hint(void addr)
515	{
516	return ((struct work_struct *) addr)->func;
517	}
518
519	static bool work_is_static_object(void *addr)
520	{
521	struct work_struct *work = addr;
522
523	return test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work));
524	}
525
526	/*
527	* fixup_init is called when:
528	* - an active object is initialized
529	*/
530	static bool work_fixup_init(void *addr, enum debug_obj_state state)
531	{
532	struct work_struct *work = addr;
533
534	switch (state) {
535	case ODEBUG_STATE_ACTIVE:
536	cancel_work_sync(work);
537	debug_object_init(work, &work_debug_descr);
538	return true;
539	default:
540	return false;
541	}
542	}
543
544	/*
545	* fixup_free is called when:
546	* - an active object is freed
547	*/
548	static bool work_fixup_free(void *addr, enum debug_obj_state state)
549	{
550	struct work_struct *work = addr;
551
552	switch (state) {
553	case ODEBUG_STATE_ACTIVE:
554	cancel_work_sync(work);
555	debug_object_free(work, &work_debug_descr);
556	return true;
557	default:
558	return false;
559	}
560	}
561
562	static const struct debug_obj_descr work_debug_descr = {
563	.name = "work_struct",
564	.debug_hint = work_debug_hint,
565	.is_static_object = work_is_static_object,
566	.fixup_init = work_fixup_init,
567	.fixup_free = work_fixup_free,
568	};
569
570	static inline void debug_work_activate(struct work_struct *work)
571	{
572	debug_object_activate(work, &work_debug_descr);
573	}
574
575	static inline void debug_work_deactivate(struct work_struct *work)
576	{
577	debug_object_deactivate(work, &work_debug_descr);
578	}
579
580	void __init_work(struct work_struct *work, int onstack)
581	{
582	if (onstack)
583	debug_object_init_on_stack(work, &work_debug_descr);
584	else
585	debug_object_init(work, &work_debug_descr);
586	}
587	EXPORT_SYMBOL_GPL(__init_work);
588
589	void destroy_work_on_stack(struct work_struct *work)
590	{
591	debug_object_free(work, &work_debug_descr);
592	}
593	EXPORT_SYMBOL_GPL(destroy_work_on_stack);
594
595	void destroy_delayed_work_on_stack(struct delayed_work *work)
596	{
597	destroy_timer_on_stack(&work->timer);
598	debug_object_free(&work->work, &work_debug_descr);
599	}
600	EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack);
601
602	#else
603	static inline void debug_work_activate(struct work_struct *work) { }
604	static inline void debug_work_deactivate(struct work_struct *work) { }
605	#endif
606
607	/**
608	* worker_pool_assign_id - allocate ID and assign it to @pool
609	* @pool: the pool pointer of interest
610	*
611	* Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned
612	* successfully, -errno on failure.
613	*/
614	static int worker_pool_assign_id(struct worker_pool *pool)
615	{
616	int ret;
617
618	lockdep_assert_held(&wq_pool_mutex);
619
620	ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE,
621	GFP_KERNEL);
622	if (ret >= 0) {
623	pool->id = ret;
624	return 0;
625	}
626	return ret;
627	}
628
629	static unsigned int work_color_to_flags(int color)
630	{
631	return color << WORK_STRUCT_COLOR_SHIFT;
632	}
633
634	static int get_work_color(unsigned long work_data)
635	{
636	return (work_data >> WORK_STRUCT_COLOR_SHIFT) &
637	((1 << WORK_STRUCT_COLOR_BITS) - 1);
638	}
639
640	static int work_next_color(int color)
641	{
642	return (color + 1) % WORK_NR_COLORS;
643	}
644
645	/*
646	* While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
647	* contain the pointer to the queued pwq. Once execution starts, the flag
648	* is cleared and the high bits contain OFFQ flags and pool ID.
649	*
650	* set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
651	* and clear_work_data() can be used to set the pwq, pool or clear
652	* work->data. These functions should only be called while the work is
653	* owned - ie. while the PENDING bit is set.
654	*
655	* get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
656	* corresponding to a work. Pool is available once the work has been
657	* queued anywhere after initialization until it is sync canceled. pwq is
658	* available only while the work item is queued.
659	*
660	* %WORK_OFFQ_CANCELING is used to mark a work item which is being
661	* canceled. While being canceled, a work item may have its PENDING set
662	* but stay off timer and worklist for arbitrarily long and nobody should
663	* try to steal the PENDING bit.
664	*/
665	static inline void set_work_data(struct work_struct *work, unsigned long data,
666	unsigned long flags)
667	{
668	WARN_ON_ONCE(!work_pending(work));
669	atomic_long_set(&work->data, data \| flags \| work_static(work));
670	}
671
672	static void set_work_pwq(struct work_struct work, struct pool_workqueue pwq,
673	unsigned long extra_flags)
674	{
675	set_work_data(work, (unsigned long)pwq,
676	WORK_STRUCT_PENDING \| WORK_STRUCT_PWQ \| extra_flags);
677	}
678
679	static void set_work_pool_and_keep_pending(struct work_struct *work,
680	int pool_id)
681	{
682	set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT,
683	WORK_STRUCT_PENDING);
684	}
685
686	static void set_work_pool_and_clear_pending(struct work_struct *work,
687	int pool_id)
688	{
689	/*
690	* The following wmb is paired with the implied mb in
691	* test_and_set_bit(PENDING) and ensures all updates to @work made
692	* here are visible to and precede any updates by the next PENDING
693	* owner.
694	*/
695	smp_wmb();
696	set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0);
697	/*
698	* The following mb guarantees that previous clear of a PENDING bit
699	* will not be reordered with any speculative LOADS or STORES from
700	* work->current_func, which is executed afterwards. This possible
701	* reordering can lead to a missed execution on attempt to queue
702	* the same @work. E.g. consider this case:
703	*
704	* CPU#0 CPU#1
705	* ---------------------------- --------------------------------
706	*
707	* 1 STORE event_indicated
708	* 2 queue_work_on() {
709	* 3 test_and_set_bit(PENDING)
710	* 4 } set_..._and_clear_pending() {
711	* 5 set_work_data() # clear bit
712	* 6 smp_mb()
713	* 7 work->current_func() {
714	* 8 LOAD event_indicated
715	* }
716	*
717	* Without an explicit full barrier speculative LOAD on line 8 can
718	* be executed before CPU#0 does STORE on line 1. If that happens,
719	* CPU#0 observes the PENDING bit is still set and new execution of
720	* a @work is not queued in a hope, that CPU#1 will eventually
721	* finish the queued @work. Meanwhile CPU#1 does not see
722	* event_indicated is set, because speculative LOAD was executed
723	* before actual STORE.
724	*/
725	smp_mb();
726	}
727
728	static void clear_work_data(struct work_struct *work)
729	{
730	smp_wmb(); /* see set_work_pool_and_clear_pending() */
731	set_work_data(work, WORK_STRUCT_NO_POOL, 0);
732	}
733
734	static inline struct pool_workqueue *work_struct_pwq(unsigned long data)
735	{
736	return (struct pool_workqueue *)(data & WORK_STRUCT_WQ_DATA_MASK);
737	}
738
739	static struct pool_workqueue get_work_pwq(struct work_struct work)
740	{
741	unsigned long data = atomic_long_read(&work->data);
742
743	if (data & WORK_STRUCT_PWQ)
744	return work_struct_pwq(data);
745	else
746	return NULL;
747	}
748
749	/**
750	* get_work_pool - return the worker_pool a given work was associated with
751	* @work: the work item of interest
752	*
753	* Pools are created and destroyed under wq_pool_mutex, and allows read
754	* access under RCU read lock. As such, this function should be
755	* called under wq_pool_mutex or inside of a rcu_read_lock() region.
756	*
757	* All fields of the returned pool are accessible as long as the above
758	* mentioned locking is in effect. If the returned pool needs to be used
759	* beyond the critical section, the caller is responsible for ensuring the
760	* returned pool is and stays online.
761	*
762	* Return: The worker_pool @work was last associated with. %NULL if none.
763	*/
764	static struct worker_pool get_work_pool(struct work_struct work)
765	{
766	unsigned long data = atomic_long_read(&work->data);
767	int pool_id;
768
769	assert_rcu_or_pool_mutex();
770
771	if (data & WORK_STRUCT_PWQ)
772	return work_struct_pwq(data)->pool;
773
774	pool_id = data >> WORK_OFFQ_POOL_SHIFT;
775	if (pool_id == WORK_OFFQ_POOL_NONE)
776	return NULL;
777
778	return idr_find(&worker_pool_idr, pool_id);
779	}
780
781	/**
782	* get_work_pool_id - return the worker pool ID a given work is associated with
783	* @work: the work item of interest
784	*
785	* Return: The worker_pool ID @work was last associated with.
786	* %WORK_OFFQ_POOL_NONE if none.
787	*/
788	static int get_work_pool_id(struct work_struct *work)
789	{
790	unsigned long data = atomic_long_read(&work->data);
791
792	if (data & WORK_STRUCT_PWQ)
793	return work_struct_pwq(data)->pool->id;
794
795	return data >> WORK_OFFQ_POOL_SHIFT;
796	}
797
798	static void mark_work_canceling(struct work_struct *work)
799	{
800	unsigned long pool_id = get_work_pool_id(work);
801
802	pool_id <<= WORK_OFFQ_POOL_SHIFT;
803	set_work_data(work, pool_id \| WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING);
804	}
805
806	static bool work_is_canceling(struct work_struct *work)
807	{
808	unsigned long data = atomic_long_read(&work->data);
809
810	return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING);
811	}
812
813	/*
814	* Policy functions. These define the policies on how the global worker
815	* pools are managed. Unless noted otherwise, these functions assume that
816	* they're being called with pool->lock held.
817	*/
818
819	/*
820	* Need to wake up a worker? Called from anything but currently
821	* running workers.
822	*
823	* Note that, because unbound workers never contribute to nr_running, this
824	* function will always return %true for unbound pools as long as the
825	* worklist isn't empty.
826	*/
827	static bool need_more_worker(struct worker_pool *pool)
828	{
829	return !list_empty(&pool->worklist) && !pool->nr_running;
830	}
831
832	/* Can I start working? Called from busy but !running workers. */
833	static bool may_start_working(struct worker_pool *pool)
834	{
835	return pool->nr_idle;
836	}
837
838	/* Do I need to keep working? Called from currently running workers. */
839	static bool keep_working(struct worker_pool *pool)
840	{
841	return !list_empty(&pool->worklist) && (pool->nr_running <= 1);
842	}
843
844	/* Do we need a new worker? Called from manager. */
845	static bool need_to_create_worker(struct worker_pool *pool)
846	{
847	return need_more_worker(pool) && !may_start_working(pool);
848	}
849
850	/* Do we have too many workers and should some go away? */
851	static bool too_many_workers(struct worker_pool *pool)
852	{
853	bool managing = pool->flags & POOL_MANAGER_ACTIVE;
854	int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
855	int nr_busy = pool->nr_workers - nr_idle;
856
857	return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
858	}
859
860	/**
861	* worker_set_flags - set worker flags and adjust nr_running accordingly
862	* @worker: self
863	* @flags: flags to set
864	*
865	* Set @flags in @worker->flags and adjust nr_running accordingly.
866	*/
867	static inline void worker_set_flags(struct worker *worker, unsigned int flags)
868	{
869	struct worker_pool *pool = worker->pool;
870
871	lockdep_assert_held(&pool->lock);
872
873	/* If transitioning into NOT_RUNNING, adjust nr_running. */
874	if ((flags & WORKER_NOT_RUNNING) &&
875	!(worker->flags & WORKER_NOT_RUNNING)) {
876	pool->nr_running--;
877	}
878
879	worker->flags \|= flags;
880	}
881
882	/**
883	* worker_clr_flags - clear worker flags and adjust nr_running accordingly
884	* @worker: self
885	* @flags: flags to clear
886	*
887	* Clear @flags in @worker->flags and adjust nr_running accordingly.
888	*/
889	static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
890	{
891	struct worker_pool *pool = worker->pool;
892	unsigned int oflags = worker->flags;
893
894	lockdep_assert_held(&pool->lock);
895
896	worker->flags &= ~flags;
897
898	/*
899	* If transitioning out of NOT_RUNNING, increment nr_running. Note
900	* that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
901	* of multiple flags, not a single flag.
902	*/
903	if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
904	if (!(worker->flags & WORKER_NOT_RUNNING))
905	pool->nr_running++;
906	}
907
908	/* Return the first idle worker. Called with pool->lock held. */
909	static struct worker first_idle_worker(struct worker_pool pool)
910	{
911	if (unlikely(list_empty(&pool->idle_list)))
912	return NULL;
913
914	return list_first_entry(&pool->idle_list, struct worker, entry);
915	}
916
917	/**
918	* worker_enter_idle - enter idle state
919	* @worker: worker which is entering idle state
920	*
921	* @worker is entering idle state. Update stats and idle timer if
922	* necessary.
923	*
924	* LOCKING:
925	* raw_spin_lock_irq(pool->lock).
926	*/
927	static void worker_enter_idle(struct worker *worker)
928	{
929	struct worker_pool *pool = worker->pool;
930
931	if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) \|\|
932	WARN_ON_ONCE(!list_empty(&worker->entry) &&
933	(worker->hentry.next \|\| worker->hentry.pprev)))
934	return;
935
936	/* can't use worker_set_flags(), also called from create_worker() */
937	worker->flags \|= WORKER_IDLE;
938	pool->nr_idle++;
939	worker->last_active = jiffies;
940
941	/* idle_list is LIFO */
942	list_add(&worker->entry, &pool->idle_list);
943
944	if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
945	mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
946
947	/* Sanity check nr_running. */
948	WARN_ON_ONCE(pool->nr_workers == pool->nr_idle && pool->nr_running);
949	}
950
951	/**
952	* worker_leave_idle - leave idle state
953	* @worker: worker which is leaving idle state
954	*
955	* @worker is leaving idle state. Update stats.
956	*
957	* LOCKING:
958	* raw_spin_lock_irq(pool->lock).
959	*/
960	static void worker_leave_idle(struct worker *worker)
961	{
962	struct worker_pool *pool = worker->pool;
963
964	if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
965	return;
966	worker_clr_flags(worker, WORKER_IDLE);
967	pool->nr_idle--;
968	list_del_init(&worker->entry);
969	}
970
971	/**
972	* find_worker_executing_work - find worker which is executing a work
973	* @pool: pool of interest
974	* @work: work to find worker for
975	*
976	* Find a worker which is executing @work on @pool by searching
977	* @pool->busy_hash which is keyed by the address of @work. For a worker
978	* to match, its current execution should match the address of @work and
979	* its work function. This is to avoid unwanted dependency between
980	* unrelated work executions through a work item being recycled while still
981	* being executed.
982	*
983	* This is a bit tricky. A work item may be freed once its execution
984	* starts and nothing prevents the freed area from being recycled for
985	* another work item. If the same work item address ends up being reused
986	* before the original execution finishes, workqueue will identify the
987	* recycled work item as currently executing and make it wait until the
988	* current execution finishes, introducing an unwanted dependency.
989	*
990	* This function checks the work item address and work function to avoid
991	* false positives. Note that this isn't complete as one may construct a
992	* work function which can introduce dependency onto itself through a
993	* recycled work item. Well, if somebody wants to shoot oneself in the
994	* foot that badly, there's only so much we can do, and if such deadlock
995	* actually occurs, it should be easy to locate the culprit work function.
996	*
997	* CONTEXT:
998	* raw_spin_lock_irq(pool->lock).
999	*
1000	* Return:
1001	* Pointer to worker which is executing @work if found, %NULL
1002	* otherwise.
1003	*/
1004	static struct worker find_worker_executing_work(struct worker_pool pool,
1005	struct work_struct *work)
1006	{
1007	struct worker *worker;
1008
1009	hash_for_each_possible(pool->busy_hash, worker, hentry,
1010	(unsigned long)work)
1011	if (worker->current_work == work &&
1012	worker->current_func == work->func)
1013	return worker;
1014
1015	return NULL;
1016	}
1017
1018	/**
1019	* move_linked_works - move linked works to a list
1020	* @work: start of series of works to be scheduled
1021	* @head: target list to append @work to
1022	* @nextp: out parameter for nested worklist walking
1023	*
1024	* Schedule linked works starting from @work to @head. Work series to be
1025	* scheduled starts at @work and includes any consecutive work with
1026	* WORK_STRUCT_LINKED set in its predecessor. See assign_work() for details on
1027	* @nextp.
1028	*
1029	* CONTEXT:
1030	* raw_spin_lock_irq(pool->lock).
1031	*/
1032	static void move_linked_works(struct work_struct work, struct list_head head,
1033	struct work_struct **nextp)
1034	{
1035	struct work_struct *n;
1036
1037	/*
1038	* Linked worklist will always end before the end of the list,
1039	* use NULL for list head.
1040	*/
1041	list_for_each_entry_safe_from(work, n, NULL, entry) {
1042	list_move_tail(&work->entry, head);
1043	if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
1044	break;
1045	}
1046
1047	/*
1048	* If we're already inside safe list traversal and have moved
1049	* multiple works to the scheduled queue, the next position
1050	* needs to be updated.
1051	*/
1052	if (nextp)
1053	*nextp = n;
1054	}
1055
1056	/**
1057	* assign_work - assign a work item and its linked work items to a worker
1058	* @work: work to assign
1059	* @worker: worker to assign to
1060	* @nextp: out parameter for nested worklist walking
1061	*
1062	* Assign @work and its linked work items to @worker. If @work is already being
1063	* executed by another worker in the same pool, it'll be punted there.
1064	*
1065	* If @nextp is not NULL, it's updated to point to the next work of the last
1066	* scheduled work. This allows assign_work() to be nested inside
1067	* list_for_each_entry_safe().
1068	*
1069	* Returns %true if @work was successfully assigned to @worker. %false if @work
1070	* was punted to another worker already executing it.
1071	*/
1072	static bool assign_work(struct work_struct work, struct worker worker,
1073	struct work_struct **nextp)
1074	{
1075	struct worker_pool *pool = worker->pool;
1076	struct worker *collision;
1077
1078	lockdep_assert_held(&pool->lock);
1079
1080	/*
1081	* A single work shouldn't be executed concurrently by multiple workers.
1082	* __queue_work() ensures that @work doesn't jump to a different pool
1083	* while still running in the previous pool. Here, we should ensure that
1084	* @work is not executed concurrently by multiple workers from the same
1085	* pool. Check whether anyone is already processing the work. If so,
1086	* defer the work to the currently executing one.
1087	*/
1088	collision = find_worker_executing_work(pool, work);
1089	if (unlikely(collision)) {
1090	move_linked_works(work, &collision->scheduled, nextp);
1091	return false;
1092	}
1093
1094	move_linked_works(work, &worker->scheduled, nextp);
1095	return true;
1096	}
1097
1098	/**
1099	* kick_pool - wake up an idle worker if necessary
1100	* @pool: pool to kick
1101	*
1102	* @pool may have pending work items. Wake up worker if necessary. Returns
1103	* whether a worker was woken up.
1104	*/
1105	static bool kick_pool(struct worker_pool *pool)
1106	{
1107	struct worker *worker = first_idle_worker(pool);
1108	struct task_struct *p;
1109
1110	lockdep_assert_held(&pool->lock);
1111
1112	if (!need_more_worker(pool) \|\| !worker)
1113	return false;
1114
1115	p = worker->task;
1116
1117	#ifdef CONFIG_SMP
1118	/*
1119	* Idle @worker is about to execute @work and waking up provides an
1120	* opportunity to migrate @worker at a lower cost by setting the task's
1121	* wake_cpu field. Let's see if we want to move @worker to improve
1122	* execution locality.
1123	*
1124	* We're waking the worker that went idle the latest and there's some
1125	* chance that @worker is marked idle but hasn't gone off CPU yet. If
1126	* so, setting the wake_cpu won't do anything. As this is a best-effort
1127	* optimization and the race window is narrow, let's leave as-is for
1128	* now. If this becomes pronounced, we can skip over workers which are
1129	* still on cpu when picking an idle worker.
1130	*
1131	* If @pool has non-strict affinity, @worker might have ended up outside
1132	* its affinity scope. Repatriate.
1133	*/
1134	if (!pool->attrs->affn_strict &&
1135	!cpumask_test_cpu(p->wake_cpu, pool->attrs->__pod_cpumask)) {
1136	struct work_struct *work = list_first_entry(&pool->worklist,
1137	struct work_struct, entry);
1138	p->wake_cpu = cpumask_any_distribute(pool->attrs->__pod_cpumask);
1139	get_work_pwq(work)->stats[PWQ_STAT_REPATRIATED]++;
1140	}
1141	#endif
1142	wake_up_process(p);
1143	return true;
1144	}
1145
1146	#ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT
1147
1148	/*
1149	* Concurrency-managed per-cpu work items that hog CPU for longer than
1150	* wq_cpu_intensive_thresh_us trigger the automatic CPU_INTENSIVE mechanism,
1151	* which prevents them from stalling other concurrency-managed work items. If a
1152	* work function keeps triggering this mechanism, it's likely that the work item
1153	* should be using an unbound workqueue instead.
1154	*
1155	* wq_cpu_intensive_report() tracks work functions which trigger such conditions
1156	* and report them so that they can be examined and converted to use unbound
1157	* workqueues as appropriate. To avoid flooding the console, each violating work
1158	* function is tracked and reported with exponential backoff.
1159	*/
1160	#define WCI_MAX_ENTS 128
1161
1162	struct wci_ent {
1163	work_func_t func;
1164	atomic64_t cnt;
1165	struct hlist_node hash_node;
1166	};
1167
1168	static struct wci_ent wci_ents[WCI_MAX_ENTS];
1169	static int wci_nr_ents;
1170	static DEFINE_RAW_SPINLOCK(wci_lock);
1171	static DEFINE_HASHTABLE(wci_hash, ilog2(WCI_MAX_ENTS));
1172
1173	static struct wci_ent *wci_find_ent(work_func_t func)
1174	{
1175	struct wci_ent *ent;
1176
1177	hash_for_each_possible_rcu(wci_hash, ent, hash_node,
1178	(unsigned long)func) {
1179	if (ent->func == func)
1180	return ent;
1181	}
1182	return NULL;
1183	}
1184
1185	static void wq_cpu_intensive_report(work_func_t func)
1186	{
1187	struct wci_ent *ent;
1188
1189	restart:
1190	ent = wci_find_ent(func);
1191	if (ent) {
1192	u64 cnt;
1193
1194	/*
1195	* Start reporting from the fourth time and back off
1196	* exponentially.
1197	*/
1198	cnt = atomic64_inc_return_relaxed(&ent->cnt);
1199	if (cnt >= 4 && is_power_of_2(cnt))
1200	printk_deferred(KERN_WARNING "workqueue: %ps hogged CPU for >%luus %llu times, consider switching to WQ_UNBOUND\n",
1201	ent->func, wq_cpu_intensive_thresh_us,
1202	atomic64_read(&ent->cnt));
1203	return;
1204	}
1205
1206	/*
1207	* @func is a new violation. Allocate a new entry for it. If wcn_ents[]
1208	* is exhausted, something went really wrong and we probably made enough
1209	* noise already.
1210	*/
1211	if (wci_nr_ents >= WCI_MAX_ENTS)
1212	return;
1213
1214	raw_spin_lock(&wci_lock);
1215
1216	if (wci_nr_ents >= WCI_MAX_ENTS) {
1217	raw_spin_unlock(&wci_lock);
1218	return;
1219	}
1220
1221	if (wci_find_ent(func)) {
1222	raw_spin_unlock(&wci_lock);
1223	goto restart;
1224	}
1225
1226	ent = &wci_ents[wci_nr_ents++];
1227	ent->func = func;
1228	atomic64_set(&ent->cnt, 1);
1229	hash_add_rcu(wci_hash, &ent->hash_node, (unsigned long)func);
1230
1231	raw_spin_unlock(&wci_lock);
1232	}
1233
1234	#else /* CONFIG_WQ_CPU_INTENSIVE_REPORT */
1235	static void wq_cpu_intensive_report(work_func_t func) {}
1236	#endif /* CONFIG_WQ_CPU_INTENSIVE_REPORT */
1237
1238	/**
1239	* wq_worker_running - a worker is running again
1240	* @task: task waking up
1241	*
1242	* This function is called when a worker returns from schedule()
1243	*/
1244	void wq_worker_running(struct task_struct *task)
1245	{
1246	struct worker *worker = kthread_data(task);
1247
1248	if (!READ_ONCE(worker->sleeping))
1249	return;
1250
1251	/*
1252	* If preempted by unbind_workers() between the WORKER_NOT_RUNNING check
1253	* and the nr_running increment below, we may ruin the nr_running reset
1254	* and leave with an unexpected pool->nr_running == 1 on the newly unbound
1255	* pool. Protect against such race.
1256	*/
1257	preempt_disable();
1258	if (!(worker->flags & WORKER_NOT_RUNNING))
1259	worker->pool->nr_running++;
1260	preempt_enable();
1261
1262	/*
1263	* CPU intensive auto-detection cares about how long a work item hogged
1264	* CPU without sleeping. Reset the starting timestamp on wakeup.
1265	*/
1266	worker->current_at = worker->task->se.sum_exec_runtime;
1267
1268	WRITE_ONCE(worker->sleeping, 0);
1269	}
1270
1271	/**
1272	* wq_worker_sleeping - a worker is going to sleep
1273	* @task: task going to sleep
1274	*
1275	* This function is called from schedule() when a busy worker is
1276	* going to sleep.
1277	*/
1278	void wq_worker_sleeping(struct task_struct *task)
1279	{
1280	struct worker *worker = kthread_data(task);
1281	struct worker_pool *pool;
1282
1283	/*
1284	* Rescuers, which may not have all the fields set up like normal
1285	* workers, also reach here, let's not access anything before
1286	* checking NOT_RUNNING.
1287	*/
1288	if (worker->flags & WORKER_NOT_RUNNING)
1289	return;
1290
1291	pool = worker->pool;
1292
1293	/* Return if preempted before wq_worker_running() was reached */
1294	if (READ_ONCE(worker->sleeping))
1295	return;
1296
1297	WRITE_ONCE(worker->sleeping, 1);
1298	raw_spin_lock_irq(&pool->lock);
1299
1300	/*
1301	* Recheck in case unbind_workers() preempted us. We don't
1302	* want to decrement nr_running after the worker is unbound
1303	* and nr_running has been reset.
1304	*/
1305	if (worker->flags & WORKER_NOT_RUNNING) {
1306	raw_spin_unlock_irq(&pool->lock);
1307	return;
1308	}
1309
1310	pool->nr_running--;
1311	if (kick_pool(pool))
1312	worker->current_pwq->stats[PWQ_STAT_CM_WAKEUP]++;
1313
1314	raw_spin_unlock_irq(&pool->lock);
1315	}
1316
1317	/**
1318	* wq_worker_tick - a scheduler tick occurred while a kworker is running
1319	* @task: task currently running
1320	*
1321	* Called from scheduler_tick(). We're in the IRQ context and the current
1322	* worker's fields which follow the 'K' locking rule can be accessed safely.
1323	*/
1324	void wq_worker_tick(struct task_struct *task)
1325	{
1326	struct worker *worker = kthread_data(task);
1327	struct pool_workqueue *pwq = worker->current_pwq;
1328	struct worker_pool *pool = worker->pool;
1329
1330	if (!pwq)
1331	return;
1332
1333	pwq->stats[PWQ_STAT_CPU_TIME] += TICK_USEC;
1334
1335	if (!wq_cpu_intensive_thresh_us)
1336	return;
1337
1338	/*
1339	* If the current worker is concurrency managed and hogged the CPU for
1340	* longer than wq_cpu_intensive_thresh_us, it's automatically marked
1341	* CPU_INTENSIVE to avoid stalling other concurrency-managed work items.
1342	*
1343	* Set @worker->sleeping means that @worker is in the process of
1344	* switching out voluntarily and won't be contributing to
1345	* @pool->nr_running until it wakes up. As wq_worker_sleeping() also
1346	* decrements ->nr_running, setting CPU_INTENSIVE here can lead to
1347	* double decrements. The task is releasing the CPU anyway. Let's skip.
1348	* We probably want to make this prettier in the future.
1349	*/
1350	if ((worker->flags & WORKER_NOT_RUNNING) \|\| READ_ONCE(worker->sleeping) \|\|
1351	worker->task->se.sum_exec_runtime - worker->current_at <
1352	wq_cpu_intensive_thresh_us * NSEC_PER_USEC)
1353	return;
1354
1355	raw_spin_lock(&pool->lock);
1356
1357	worker_set_flags(worker, WORKER_CPU_INTENSIVE);
1358	wq_cpu_intensive_report(worker->current_func);
1359	pwq->stats[PWQ_STAT_CPU_INTENSIVE]++;
1360
1361	if (kick_pool(pool))
1362	pwq->stats[PWQ_STAT_CM_WAKEUP]++;
1363
1364	raw_spin_unlock(&pool->lock);
1365	}
1366
1367	/**
1368	* wq_worker_last_func - retrieve worker's last work function
1369	* @task: Task to retrieve last work function of.
1370	*
1371	* Determine the last function a worker executed. This is called from
1372	* the scheduler to get a worker's last known identity.
1373	*
1374	* CONTEXT:
1375	* raw_spin_lock_irq(rq->lock)
1376	*
1377	* This function is called during schedule() when a kworker is going
1378	* to sleep. It's used by psi to identify aggregation workers during
1379	* dequeuing, to allow periodic aggregation to shut-off when that
1380	* worker is the last task in the system or cgroup to go to sleep.
1381	*
1382	* As this function doesn't involve any workqueue-related locking, it
1383	* only returns stable values when called from inside the scheduler's
1384	* queuing and dequeuing paths, when @task, which must be a kworker,
1385	* is guaranteed to not be processing any works.
1386	*
1387	* Return:
1388	* The last work function %current executed as a worker, NULL if it
1389	* hasn't executed any work yet.
1390	*/
1391	work_func_t wq_worker_last_func(struct task_struct *task)
1392	{
1393	struct worker *worker = kthread_data(task);
1394
1395	return worker->last_func;
1396	}
1397
1398	/**
1399	* get_pwq - get an extra reference on the specified pool_workqueue
1400	* @pwq: pool_workqueue to get
1401	*
1402	* Obtain an extra reference on @pwq. The caller should guarantee that
1403	* @pwq has positive refcnt and be holding the matching pool->lock.
1404	*/
1405	static void get_pwq(struct pool_workqueue *pwq)
1406	{
1407	lockdep_assert_held(&pwq->pool->lock);
1408	WARN_ON_ONCE(pwq->refcnt <= 0);
1409	pwq->refcnt++;
1410	}
1411
1412	/**
1413	* put_pwq - put a pool_workqueue reference
1414	* @pwq: pool_workqueue to put
1415	*
1416	* Drop a reference of @pwq. If its refcnt reaches zero, schedule its
1417	* destruction. The caller should be holding the matching pool->lock.
1418	*/
1419	static void put_pwq(struct pool_workqueue *pwq)
1420	{
1421	lockdep_assert_held(&pwq->pool->lock);
1422	if (likely(--pwq->refcnt))
1423	return;
1424	/*
1425	* @pwq can't be released under pool->lock, bounce to a dedicated
1426	* kthread_worker to avoid A-A deadlocks.
1427	*/
1428	kthread_queue_work(pwq_release_worker, &pwq->release_work);
1429	}
1430
1431	/**
1432	* put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
1433	* @pwq: pool_workqueue to put (can be %NULL)
1434	*
1435	* put_pwq() with locking. This function also allows %NULL @pwq.
1436	*/
1437	static void put_pwq_unlocked(struct pool_workqueue *pwq)
1438	{
1439	if (pwq) {
1440	/*
1441	* As both pwqs and pools are RCU protected, the
1442	* following lock operations are safe.
1443	*/
1444	raw_spin_lock_irq(&pwq->pool->lock);
1445	put_pwq(pwq);
1446	raw_spin_unlock_irq(&pwq->pool->lock);
1447	}
1448	}
1449
1450	static void pwq_activate_inactive_work(struct work_struct *work)
1451	{
1452	struct pool_workqueue *pwq = get_work_pwq(work);
1453
1454	trace_workqueue_activate_work(work);
1455	if (list_empty(&pwq->pool->worklist))
1456	pwq->pool->watchdog_ts = jiffies;
1457	move_linked_works(work, &pwq->pool->worklist, NULL);
1458	__clear_bit(WORK_STRUCT_INACTIVE_BIT, work_data_bits(work));
1459	pwq->nr_active++;
1460	}
1461
1462	static void pwq_activate_first_inactive(struct pool_workqueue *pwq)
1463	{
1464	struct work_struct *work = list_first_entry(&pwq->inactive_works,
1465	struct work_struct, entry);
1466
1467	pwq_activate_inactive_work(work);
1468	}
1469
1470	/**
1471	* pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
1472	* @pwq: pwq of interest
1473	* @work_data: work_data of work which left the queue
1474	*
1475	* A work either has completed or is removed from pending queue,
1476	* decrement nr_in_flight of its pwq and handle workqueue flushing.
1477	*
1478	* CONTEXT:
1479	* raw_spin_lock_irq(pool->lock).
1480	*/
1481	static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, unsigned long work_data)
1482	{
1483	int color = get_work_color(work_data);
1484
1485	if (!(work_data & WORK_STRUCT_INACTIVE)) {
1486	pwq->nr_active--;
1487	if (!list_empty(&pwq->inactive_works)) {
1488	/* one down, submit an inactive one */
1489	if (pwq->nr_active < pwq->max_active)
1490	pwq_activate_first_inactive(pwq);
1491	}
1492	}
1493
1494	pwq->nr_in_flight[color]--;
1495
1496	/* is flush in progress and are we at the flushing tip? */
1497	if (likely(pwq->flush_color != color))
1498	goto out_put;
1499
1500	/* are there still in-flight works? */
1501	if (pwq->nr_in_flight[color])
1502	goto out_put;
1503
1504	/* this pwq is done, clear flush_color */
1505	pwq->flush_color = -1;
1506
1507	/*
1508	* If this was the last pwq, wake up the first flusher. It
1509	* will handle the rest.
1510	*/
1511	if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush))
1512	complete(&pwq->wq->first_flusher->done);
1513	out_put:
1514	put_pwq(pwq);
1515	}
1516
1517	/**
1518	* try_to_grab_pending - steal work item from worklist and disable irq
1519	* @work: work item to steal
1520	* @is_dwork: @work is a delayed_work
1521	* @flags: place to store irq state
1522	*
1523	* Try to grab PENDING bit of @work. This function can handle @work in any
1524	* stable state - idle, on timer or on worklist.
1525	*
1526	* Return:
1527	*
1528	* ======== ================================================================
1529	* 1 if @work was pending and we successfully stole PENDING
1530	* 0 if @work was idle and we claimed PENDING
1531	* -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
1532	* -ENOENT if someone else is canceling @work, this state may persist
1533	* for arbitrarily long
1534	* ======== ================================================================
1535	*
1536	* Note:
1537	* On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
1538	* interrupted while holding PENDING and @work off queue, irq must be
1539	* disabled on entry. This, combined with delayed_work->timer being
1540	* irqsafe, ensures that we return -EAGAIN for finite short period of time.
1541	*
1542	* On successful return, >= 0, irq is disabled and the caller is
1543	* responsible for releasing it using local_irq_restore(*@flags).
1544	*
1545	* This function is safe to call from any context including IRQ handler.
1546	*/
1547	static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
1548	unsigned long *flags)
1549	{
1550	struct worker_pool *pool;
1551	struct pool_workqueue *pwq;
1552
1553	local_irq_save(*flags);
1554
1555	/* try to steal the timer if it exists */
1556	if (is_dwork) {
1557	struct delayed_work *dwork = to_delayed_work(work);
1558
1559	/*
1560	* dwork->timer is irqsafe. If del_timer() fails, it's
1561	* guaranteed that the timer is not queued anywhere and not
1562	* running on the local CPU.
1563	*/
1564	if (likely(del_timer(&dwork->timer)))
1565	return 1;
1566	}
1567
1568	/* try to claim PENDING the normal way */
1569	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
1570	return 0;
1571
1572	rcu_read_lock();
1573	/*
1574	* The queueing is in progress, or it is already queued. Try to
1575	* steal it from ->worklist without clearing WORK_STRUCT_PENDING.
1576	*/
1577	pool = get_work_pool(work);
1578	if (!pool)
1579	goto fail;
1580
1581	raw_spin_lock(&pool->lock);
1582	/*
1583	* work->data is guaranteed to point to pwq only while the work
1584	* item is queued on pwq->wq, and both updating work->data to point
1585	* to pwq on queueing and to pool on dequeueing are done under
1586	* pwq->pool->lock. This in turn guarantees that, if work->data
1587	* points to pwq which is associated with a locked pool, the work
1588	* item is currently queued on that pool.
1589	*/
1590	pwq = get_work_pwq(work);
1591	if (pwq && pwq->pool == pool) {
1592	debug_work_deactivate(work);
1593
1594	/*
1595	* A cancelable inactive work item must be in the
1596	* pwq->inactive_works since a queued barrier can't be
1597	* canceled (see the comments in insert_wq_barrier()).
1598	*
1599	* An inactive work item cannot be grabbed directly because
1600	* it might have linked barrier work items which, if left
1601	* on the inactive_works list, will confuse pwq->nr_active
1602	* management later on and cause stall. Make sure the work
1603	* item is activated before grabbing.
1604	*/
1605	if (*work_data_bits(work) & WORK_STRUCT_INACTIVE)
1606	pwq_activate_inactive_work(work);
1607
1608	list_del_init(&work->entry);
1609	pwq_dec_nr_in_flight(pwq, *work_data_bits(work));
1610
1611	/* work->data points to pwq iff queued, point to pool */
1612	set_work_pool_and_keep_pending(work, pool->id);
1613
1614	raw_spin_unlock(&pool->lock);
1615	rcu_read_unlock();
1616	return 1;
1617	}
1618	raw_spin_unlock(&pool->lock);
1619	fail:
1620	rcu_read_unlock();
1621	local_irq_restore(*flags);
1622	if (work_is_canceling(work))
1623	return -ENOENT;
1624	cpu_relax();
1625	return -EAGAIN;
1626	}
1627
1628	/**
1629	* insert_work - insert a work into a pool
1630	* @pwq: pwq @work belongs to
1631	* @work: work to insert
1632	* @head: insertion point
1633	* @extra_flags: extra WORK_STRUCT_* flags to set
1634	*
1635	* Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
1636	* work_struct flags.
1637	*
1638	* CONTEXT:
1639	* raw_spin_lock_irq(pool->lock).
1640	*/
1641	static void insert_work(struct pool_workqueue pwq, struct work_struct work,
1642	struct list_head *head, unsigned int extra_flags)
1643	{
1644	debug_work_activate(work);
1645
1646	/* record the work call stack in order to print it in KASAN reports */
1647	kasan_record_aux_stack_noalloc(work);
1648
1649	/* we own @work, set data and link */
1650	set_work_pwq(work, pwq, extra_flags);
1651	list_add_tail(&work->entry, head);
1652	get_pwq(pwq);
1653	}
1654
1655	/*
1656	* Test whether @work is being queued from another work executing on the
1657	* same workqueue.
1658	*/
1659	static bool is_chained_work(struct workqueue_struct *wq)
1660	{
1661	struct worker *worker;
1662
1663	worker = current_wq_worker();
1664	/*
1665	* Return %true iff I'm a worker executing a work item on @wq. If
1666	* I'm @worker, it's safe to dereference it without locking.
1667	*/
1668	return worker && worker->current_pwq->wq == wq;
1669	}
1670
1671	/*
1672	* When queueing an unbound work item to a wq, prefer local CPU if allowed
1673	* by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to
1674	* avoid perturbing sensitive tasks.
1675	*/
1676	static int wq_select_unbound_cpu(int cpu)
1677	{
1678	int new_cpu;
1679
1680	if (likely(!wq_debug_force_rr_cpu)) {
1681	if (cpumask_test_cpu(cpu, wq_unbound_cpumask))
1682	return cpu;
1683	} else {
1684	pr_warn_once("workqueue: round-robin CPU selection forced, expect performance impact\n");
1685	}
1686
1687	new_cpu = __this_cpu_read(wq_rr_cpu_last);
1688	new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask);
1689	if (unlikely(new_cpu >= nr_cpu_ids)) {
1690	new_cpu = cpumask_first_and(wq_unbound_cpumask, cpu_online_mask);
1691	if (unlikely(new_cpu >= nr_cpu_ids))
1692	return cpu;
1693	}
1694	__this_cpu_write(wq_rr_cpu_last, new_cpu);
1695
1696	return new_cpu;
1697	}
1698
1699	static void __queue_work(int cpu, struct workqueue_struct *wq,
1700	struct work_struct *work)
1701	{
1702	struct pool_workqueue *pwq;
1703	struct worker_pool last_pool, pool;
1704	unsigned int work_flags;
1705	unsigned int req_cpu = cpu;
1706
1707	/*
1708	* While a work item is PENDING && off queue, a task trying to
1709	* steal the PENDING will busy-loop waiting for it to either get
1710	* queued or lose PENDING. Grabbing PENDING and queueing should
1711	* happen with IRQ disabled.
1712	*/
1713	lockdep_assert_irqs_disabled();
1714
1715
1716	/*
1717	* For a draining wq, only works from the same workqueue are
1718	* allowed. The __WQ_DESTROYING helps to spot the issue that
1719	* queues a new work item to a wq after destroy_workqueue(wq).
1720	*/
1721	if (unlikely(wq->flags & (__WQ_DESTROYING \| __WQ_DRAINING) &&
1722	WARN_ON_ONCE(!is_chained_work(wq))))
1723	return;
1724	rcu_read_lock();
1725	retry:
1726	/* pwq which will be used unless @work is executing elsewhere */
1727	if (req_cpu == WORK_CPU_UNBOUND) {
1728	if (wq->flags & WQ_UNBOUND)
1729	cpu = wq_select_unbound_cpu(raw_smp_processor_id());
1730	else
1731	cpu = raw_smp_processor_id();
1732	}
1733
1734	pwq = rcu_dereference(*per_cpu_ptr(wq->cpu_pwq, cpu));
1735	pool = pwq->pool;
1736
1737	/*
1738	* If @work was previously on a different pool, it might still be
1739	* running there, in which case the work needs to be queued on that
1740	* pool to guarantee non-reentrancy.
1741	*/
1742	last_pool = get_work_pool(work);
1743	if (last_pool && last_pool != pool) {
1744	struct worker *worker;
1745
1746	raw_spin_lock(&last_pool->lock);
1747
1748	worker = find_worker_executing_work(last_pool, work);
1749
1750	if (worker && worker->current_pwq->wq == wq) {
1751	pwq = worker->current_pwq;
1752	pool = pwq->pool;
1753	WARN_ON_ONCE(pool != last_pool);
1754	} else {
1755	/* meh... not running there, queue here */
1756	raw_spin_unlock(&last_pool->lock);
1757	raw_spin_lock(&pool->lock);
1758	}
1759	} else {
1760	raw_spin_lock(&pool->lock);
1761	}
1762
1763	/*
1764	* pwq is determined and locked. For unbound pools, we could have raced
1765	* with pwq release and it could already be dead. If its refcnt is zero,
1766	* repeat pwq selection. Note that unbound pwqs never die without
1767	* another pwq replacing it in cpu_pwq or while work items are executing
1768	* on it, so the retrying is guaranteed to make forward-progress.
1769	*/
1770	if (unlikely(!pwq->refcnt)) {
1771	if (wq->flags & WQ_UNBOUND) {
1772	raw_spin_unlock(&pool->lock);
1773	cpu_relax();
1774	goto retry;
1775	}
1776	/* oops */
1777	WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
1778	wq->name, cpu);
1779	}
1780
1781	/* pwq determined, queue */
1782	trace_workqueue_queue_work(req_cpu, pwq, work);
1783
1784	if (WARN_ON(!list_empty(&work->entry)))
1785	goto out;
1786
1787	pwq->nr_in_flight[pwq->work_color]++;
1788	work_flags = work_color_to_flags(pwq->work_color);
1789
1790	if (likely(pwq->nr_active < pwq->max_active)) {
1791	if (list_empty(&pool->worklist))
1792	pool->watchdog_ts = jiffies;
1793
1794	trace_workqueue_activate_work(work);
1795	pwq->nr_active++;
1796	insert_work(pwq, work, &pool->worklist, work_flags);
1797	kick_pool(pool);
1798	} else {
1799	work_flags \|= WORK_STRUCT_INACTIVE;
1800	insert_work(pwq, work, &pwq->inactive_works, work_flags);
1801	}
1802
1803	out:
1804	raw_spin_unlock(&pool->lock);
1805	rcu_read_unlock();
1806	}
1807
1808	/**
1809	* queue_work_on - queue work on specific cpu
1810	* @cpu: CPU number to execute work on
1811	* @wq: workqueue to use
1812	* @work: work to queue
1813	*
1814	* We queue the work to a specific CPU, the caller must ensure it
1815	* can't go away. Callers that fail to ensure that the specified
1816	* CPU cannot go away will execute on a randomly chosen CPU.
1817	* But note well that callers specifying a CPU that never has been
1818	* online will get a splat.
1819	*
1820	* Return: %false if @work was already on a queue, %true otherwise.
1821	*/
1822	bool queue_work_on(int cpu, struct workqueue_struct *wq,
1823	struct work_struct *work)
1824	{
1825	bool ret = false;
1826	unsigned long flags;
1827
1828	local_irq_save(flags);
1829
1830	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1831	__queue_work(cpu, wq, work);
1832	ret = true;
1833	}
1834
1835	local_irq_restore(flags);
1836	return ret;
1837	}
1838	EXPORT_SYMBOL(queue_work_on);
1839
1840	/**
1841	* select_numa_node_cpu - Select a CPU based on NUMA node
1842	* @node: NUMA node ID that we want to select a CPU from
1843	*
1844	* This function will attempt to find a "random" cpu available on a given
1845	* node. If there are no CPUs available on the given node it will return
1846	* WORK_CPU_UNBOUND indicating that we should just schedule to any
1847	* available CPU if we need to schedule this work.
1848	*/
1849	static int select_numa_node_cpu(int node)
1850	{
1851	int cpu;
1852
1853	/* Delay binding to CPU if node is not valid or online */
1854	if (node < 0 \|\| node >= MAX_NUMNODES \|\| !node_online(node))
1855	return WORK_CPU_UNBOUND;
1856
1857	/* Use local node/cpu if we are already there */
1858	cpu = raw_smp_processor_id();
1859	if (node == cpu_to_node(cpu))
1860	return cpu;
1861
1862	/* Use "random" otherwise know as "first" online CPU of node */
1863	cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask);
1864
1865	/* If CPU is valid return that, otherwise just defer */
1866	return cpu < nr_cpu_ids ? cpu : WORK_CPU_UNBOUND;
1867	}
1868
1869	/**
1870	* queue_work_node - queue work on a "random" cpu for a given NUMA node
1871	* @node: NUMA node that we are targeting the work for
1872	* @wq: workqueue to use
1873	* @work: work to queue
1874	*
1875	* We queue the work to a "random" CPU within a given NUMA node. The basic
1876	* idea here is to provide a way to somehow associate work with a given
1877	* NUMA node.
1878	*
1879	* This function will only make a best effort attempt at getting this onto
1880	* the right NUMA node. If no node is requested or the requested node is
1881	* offline then we just fall back to standard queue_work behavior.
1882	*
1883	* Currently the "random" CPU ends up being the first available CPU in the
1884	* intersection of cpu_online_mask and the cpumask of the node, unless we
1885	* are running on the node. In that case we just use the current CPU.
1886	*
1887	* Return: %false if @work was already on a queue, %true otherwise.
1888	*/
1889	bool queue_work_node(int node, struct workqueue_struct *wq,
1890	struct work_struct *work)
1891	{
1892	unsigned long flags;
1893	bool ret = false;
1894
1895	/*
1896	* This current implementation is specific to unbound workqueues.
1897	* Specifically we only return the first available CPU for a given
1898	* node instead of cycling through individual CPUs within the node.
1899	*
1900	* If this is used with a per-cpu workqueue then the logic in
1901	* workqueue_select_cpu_near would need to be updated to allow for
1902	* some round robin type logic.
1903	*/
1904	WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND));
1905
1906	local_irq_save(flags);
1907
1908	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1909	int cpu = select_numa_node_cpu(node);
1910
1911	__queue_work(cpu, wq, work);
1912	ret = true;
1913	}
1914
1915	local_irq_restore(flags);
1916	return ret;
1917	}
1918	EXPORT_SYMBOL_GPL(queue_work_node);
1919
1920	void delayed_work_timer_fn(struct timer_list *t)
1921	{
1922	struct delayed_work *dwork = from_timer(dwork, t, timer);
1923
1924	/* should have been called from irqsafe timer with irq already off */
1925	__queue_work(dwork->cpu, dwork->wq, &dwork->work);
1926	}
1927	EXPORT_SYMBOL(delayed_work_timer_fn);
1928
1929	static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
1930	struct delayed_work *dwork, unsigned long delay)
1931	{
1932	struct timer_list *timer = &dwork->timer;
1933	struct work_struct *work = &dwork->work;
1934
1935	WARN_ON_ONCE(!wq);
1936	WARN_ON_ONCE(timer->function != delayed_work_timer_fn);
1937	WARN_ON_ONCE(timer_pending(timer));
1938	WARN_ON_ONCE(!list_empty(&work->entry));
1939
1940	/*
1941	* If @delay is 0, queue @dwork->work immediately. This is for
1942	* both optimization and correctness. The earliest @timer can
1943	* expire is on the closest next tick and delayed_work users depend
1944	* on that there's no such delay when @delay is 0.
1945	*/
1946	if (!delay) {
1947	__queue_work(cpu, wq, &dwork->work);
1948	return;
1949	}
1950
1951	dwork->wq = wq;
1952	dwork->cpu = cpu;
1953	timer->expires = jiffies + delay;
1954
1955	if (unlikely(cpu != WORK_CPU_UNBOUND))
1956	add_timer_on(timer, cpu);
1957	else
1958	add_timer(timer);
1959	}
1960
1961	/**
1962	* queue_delayed_work_on - queue work on specific CPU after delay
1963	* @cpu: CPU number to execute work on
1964	* @wq: workqueue to use
1965	* @dwork: work to queue
1966	* @delay: number of jiffies to wait before queueing
1967	*
1968	* Return: %false if @work was already on a queue, %true otherwise. If
1969	* @delay is zero and @dwork is idle, it will be scheduled for immediate
1970	* execution.
1971	*/
1972	bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
1973	struct delayed_work *dwork, unsigned long delay)
1974	{
1975	struct work_struct *work = &dwork->work;
1976	bool ret = false;
1977	unsigned long flags;
1978
1979	/* read the comment in __queue_work() */
1980	local_irq_save(flags);
1981
1982	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1983	__queue_delayed_work(cpu, wq, dwork, delay);
1984	ret = true;
1985	}
1986
1987	local_irq_restore(flags);
1988	return ret;
1989	}
1990	EXPORT_SYMBOL(queue_delayed_work_on);
1991
1992	/**
1993	* mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
1994	* @cpu: CPU number to execute work on
1995	* @wq: workqueue to use
1996	* @dwork: work to queue
1997	* @delay: number of jiffies to wait before queueing
1998	*
1999	* If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
2000	* modify @dwork's timer so that it expires after @delay. If @delay is
2001	* zero, @work is guaranteed to be scheduled immediately regardless of its
2002	* current state.
2003	*
2004	* Return: %false if @dwork was idle and queued, %true if @dwork was
2005	* pending and its timer was modified.
2006	*
2007	* This function is safe to call from any context including IRQ handler.
2008	* See try_to_grab_pending() for details.
2009	*/
2010	bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
2011	struct delayed_work *dwork, unsigned long delay)
2012	{
2013	unsigned long flags;
2014	int ret;
2015
2016	do {
2017	ret = try_to_grab_pending(&dwork->work, true, &flags);
2018	} while (unlikely(ret == -EAGAIN));
2019
2020	if (likely(ret >= 0)) {
2021	__queue_delayed_work(cpu, wq, dwork, delay);
2022	local_irq_restore(flags);
2023	}
2024
2025	/* -ENOENT from try_to_grab_pending() becomes %true */
2026	return ret;
2027	}
2028	EXPORT_SYMBOL_GPL(mod_delayed_work_on);
2029
2030	static void rcu_work_rcufn(struct rcu_head *rcu)
2031	{
2032	struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu);
2033
2034	/* read the comment in __queue_work() */
2035	local_irq_disable();
2036	__queue_work(WORK_CPU_UNBOUND, rwork->wq, &rwork->work);
2037	local_irq_enable();
2038	}
2039
2040	/**
2041	* queue_rcu_work - queue work after a RCU grace period
2042	* @wq: workqueue to use
2043	* @rwork: work to queue
2044	*
2045	* Return: %false if @rwork was already pending, %true otherwise. Note
2046	* that a full RCU grace period is guaranteed only after a %true return.
2047	* While @rwork is guaranteed to be executed after a %false return, the
2048	* execution may happen before a full RCU grace period has passed.
2049	*/
2050	bool queue_rcu_work(struct workqueue_struct wq, struct rcu_work rwork)
2051	{
2052	struct work_struct *work = &rwork->work;
2053
2054	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
2055	rwork->wq = wq;
2056	call_rcu_hurry(&rwork->rcu, rcu_work_rcufn);
2057	return true;
2058	}
2059
2060	return false;
2061	}
2062	EXPORT_SYMBOL(queue_rcu_work);
2063
2064	static struct worker *alloc_worker(int node)
2065	{
2066	struct worker *worker;
2067
2068	worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node);
2069	if (worker) {
2070	INIT_LIST_HEAD(&worker->entry);
2071	INIT_LIST_HEAD(&worker->scheduled);
2072	INIT_LIST_HEAD(&worker->node);
2073	/* on creation a worker is in !idle && prep state */
2074	worker->flags = WORKER_PREP;
2075	}
2076	return worker;
2077	}
2078
2079	static cpumask_t pool_allowed_cpus(struct worker_pool pool)
2080	{
2081	if (pool->cpu < 0 && pool->attrs->affn_strict)
2082	return pool->attrs->__pod_cpumask;
2083	else
2084	return pool->attrs->cpumask;
2085	}
2086
2087	/**
2088	* worker_attach_to_pool() - attach a worker to a pool
2089	* @worker: worker to be attached
2090	* @pool: the target pool
2091	*
2092	* Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and
2093	* cpu-binding of @worker are kept coordinated with the pool across
2094	* cpu-[un]hotplugs.
2095	*/
2096	static void worker_attach_to_pool(struct worker *worker,
2097	struct worker_pool *pool)
2098	{
2099	mutex_lock(&wq_pool_attach_mutex);
2100
2101	/*
2102	* The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains
2103	* stable across this function. See the comments above the flag
2104	* definition for details.
2105	*/
2106	if (pool->flags & POOL_DISASSOCIATED)
2107	worker->flags \|= WORKER_UNBOUND;
2108	else
2109	kthread_set_per_cpu(worker->task, pool->cpu);
2110
2111	if (worker->rescue_wq)
2112	set_cpus_allowed_ptr(worker->task, pool_allowed_cpus(pool));
2113
2114	list_add_tail(&worker->node, &pool->workers);
2115	worker->pool = pool;
2116
2117	mutex_unlock(&wq_pool_attach_mutex);
2118	}
2119
2120	/**
2121	* worker_detach_from_pool() - detach a worker from its pool
2122	* @worker: worker which is attached to its pool
2123	*
2124	* Undo the attaching which had been done in worker_attach_to_pool(). The
2125	* caller worker shouldn't access to the pool after detached except it has
2126	* other reference to the pool.
2127	*/
2128	static void worker_detach_from_pool(struct worker *worker)
2129	{
2130	struct worker_pool *pool = worker->pool;
2131	struct completion *detach_completion = NULL;
2132
2133	mutex_lock(&wq_pool_attach_mutex);
2134
2135	kthread_set_per_cpu(worker->task, -1);
2136	list_del(&worker->node);
2137	worker->pool = NULL;
2138
2139	if (list_empty(&pool->workers) && list_empty(&pool->dying_workers))
2140	detach_completion = pool->detach_completion;
2141	mutex_unlock(&wq_pool_attach_mutex);
2142
2143	/* clear leftover flags without pool->lock after it is detached */
2144	worker->flags &= ~(WORKER_UNBOUND \| WORKER_REBOUND);
2145
2146	if (detach_completion)
2147	complete(detach_completion);
2148	}
2149
2150	/**
2151	* create_worker - create a new workqueue worker
2152	* @pool: pool the new worker will belong to
2153	*
2154	* Create and start a new worker which is attached to @pool.
2155	*
2156	* CONTEXT:
2157	* Might sleep. Does GFP_KERNEL allocations.
2158	*
2159	* Return:
2160	* Pointer to the newly created worker.
2161	*/
2162	static struct worker create_worker(struct worker_pool pool)
2163	{
2164	struct worker *worker;
2165	int id;
2166	char id_buf[23];
2167
2168	/* ID is needed to determine kthread name */
2169	id = ida_alloc(&pool->worker_ida, GFP_KERNEL);
2170	if (id < 0) {
2171	pr_err_once("workqueue: Failed to allocate a worker ID: %pe\n",
2172	ERR_PTR(id));
2173	return NULL;
2174	}
2175
2176	worker = alloc_worker(pool->node);
2177	if (!worker) {
2178	pr_err_once("workqueue: Failed to allocate a worker\n");
2179	goto fail;
2180	}
2181
2182	worker->id = id;
2183
2184	if (pool->cpu >= 0)
2185	snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id,
2186	pool->attrs->nice < 0 ? "H" : "");
2187	else
2188	snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id);
2189
2190	worker->task = kthread_create_on_node(worker_thread, worker, pool->node,
2191	"kworker/%s", id_buf);
2192	if (IS_ERR(worker->task)) {
2193	if (PTR_ERR(worker->task) == -EINTR) {
2194	pr_err("workqueue: Interrupted when creating a worker thread \"kworker/%s\"\n",
2195	id_buf);
2196	} else {
2197	pr_err_once("workqueue: Failed to create a worker thread: %pe",
2198	worker->task);
2199	}
2200	goto fail;
2201	}
2202
2203	set_user_nice(worker->task, pool->attrs->nice);
2204	kthread_bind_mask(worker->task, pool_allowed_cpus(pool));
2205
2206	/* successful, attach the worker to the pool */
2207	worker_attach_to_pool(worker, pool);
2208
2209	/* start the newly created worker */
2210	raw_spin_lock_irq(&pool->lock);
2211
2212	worker->pool->nr_workers++;
2213	worker_enter_idle(worker);
2214	kick_pool(pool);
2215
2216	/*
2217	* @worker is waiting on a completion in kthread() and will trigger hung
2218	* check if not woken up soon. As kick_pool() might not have waken it
2219	* up, wake it up explicitly once more.
2220	*/
2221	wake_up_process(worker->task);
2222
2223	raw_spin_unlock_irq(&pool->lock);
2224
2225	return worker;
2226
2227	fail:
2228	ida_free(&pool->worker_ida, id);
2229	kfree(worker);
2230	return NULL;
2231	}
2232
2233	static void unbind_worker(struct worker *worker)
2234	{
2235	lockdep_assert_held(&wq_pool_attach_mutex);
2236
2237	kthread_set_per_cpu(worker->task, -1);
2238	if (cpumask_intersects(wq_unbound_cpumask, cpu_active_mask))
2239	WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, wq_unbound_cpumask) < 0);
2240	else
2241	WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, cpu_possible_mask) < 0);
2242	}
2243
2244	static void wake_dying_workers(struct list_head *cull_list)
2245	{
2246	struct worker worker, tmp;
2247
2248	list_for_each_entry_safe(worker, tmp, cull_list, entry) {
2249	list_del_init(&worker->entry);
2250	unbind_worker(worker);
2251	/*
2252	* If the worker was somehow already running, then it had to be
2253	* in pool->idle_list when set_worker_dying() happened or we
2254	* wouldn't have gotten here.
2255	*
2256	* Thus, the worker must either have observed the WORKER_DIE
2257	* flag, or have set its state to TASK_IDLE. Either way, the
2258	* below will be observed by the worker and is safe to do
2259	* outside of pool->lock.
2260	*/
2261	wake_up_process(worker->task);
2262	}
2263	}
2264
2265	/**
2266	* set_worker_dying - Tag a worker for destruction
2267	* @worker: worker to be destroyed
2268	* @list: transfer worker away from its pool->idle_list and into list
2269	*
2270	* Tag @worker for destruction and adjust @pool stats accordingly. The worker
2271	* should be idle.
2272	*
2273	* CONTEXT:
2274	* raw_spin_lock_irq(pool->lock).
2275	*/
2276	static void set_worker_dying(struct worker worker, struct list_head list)
2277	{
2278	struct worker_pool *pool = worker->pool;
2279
2280	lockdep_assert_held(&pool->lock);
2281	lockdep_assert_held(&wq_pool_attach_mutex);
2282
2283	/* sanity check frenzy */
2284	if (WARN_ON(worker->current_work) \|\|
2285	WARN_ON(!list_empty(&worker->scheduled)) \|\|
2286	WARN_ON(!(worker->flags & WORKER_IDLE)))
2287	return;
2288
2289	pool->nr_workers--;
2290	pool->nr_idle--;
2291
2292	worker->flags \|= WORKER_DIE;
2293
2294	list_move(&worker->entry, list);
2295	list_move(&worker->node, &pool->dying_workers);
2296	}
2297
2298	/**
2299	* idle_worker_timeout - check if some idle workers can now be deleted.
2300	* @t: The pool's idle_timer that just expired
2301	*
2302	* The timer is armed in worker_enter_idle(). Note that it isn't disarmed in
2303	* worker_leave_idle(), as a worker flicking between idle and active while its
2304	* pool is at the too_many_workers() tipping point would cause too much timer
2305	* housekeeping overhead. Since IDLE_WORKER_TIMEOUT is long enough, we just let
2306	* it expire and re-evaluate things from there.
2307	*/
2308	static void idle_worker_timeout(struct timer_list *t)
2309	{
2310	struct worker_pool *pool = from_timer(pool, t, idle_timer);
2311	bool do_cull = false;
2312
2313	if (work_pending(&pool->idle_cull_work))
2314	return;
2315
2316	raw_spin_lock_irq(&pool->lock);
2317
2318	if (too_many_workers(pool)) {
2319	struct worker *worker;
2320	unsigned long expires;
2321
2322	/* idle_list is kept in LIFO order, check the last one */
2323	worker = list_entry(pool->idle_list.prev, struct worker, entry);
2324	expires = worker->last_active + IDLE_WORKER_TIMEOUT;
2325	do_cull = !time_before(jiffies, expires);
2326
2327	if (!do_cull)
2328	mod_timer(&pool->idle_timer, expires);
2329	}
2330	raw_spin_unlock_irq(&pool->lock);
2331
2332	if (do_cull)
2333	queue_work(system_unbound_wq, &pool->idle_cull_work);
2334	}
2335
2336	/**
2337	* idle_cull_fn - cull workers that have been idle for too long.
2338	* @work: the pool's work for handling these idle workers
2339	*
2340	* This goes through a pool's idle workers and gets rid of those that have been
2341	* idle for at least IDLE_WORKER_TIMEOUT seconds.
2342	*
2343	* We don't want to disturb isolated CPUs because of a pcpu kworker being
2344	* culled, so this also resets worker affinity. This requires a sleepable
2345	* context, hence the split between timer callback and work item.
2346	*/
2347	static void idle_cull_fn(struct work_struct *work)
2348	{
2349	struct worker_pool *pool = container_of(work, struct worker_pool, idle_cull_work);
2350	LIST_HEAD(cull_list);
2351
2352	/*
2353	* Grabbing wq_pool_attach_mutex here ensures an already-running worker
2354	* cannot proceed beyong worker_detach_from_pool() in its self-destruct
2355	* path. This is required as a previously-preempted worker could run after
2356	* set_worker_dying() has happened but before wake_dying_workers() did.
2357	*/
2358	mutex_lock(&wq_pool_attach_mutex);
2359	raw_spin_lock_irq(&pool->lock);
2360
2361	while (too_many_workers(pool)) {
2362	struct worker *worker;
2363	unsigned long expires;
2364
2365	worker = list_entry(pool->idle_list.prev, struct worker, entry);
2366	expires = worker->last_active + IDLE_WORKER_TIMEOUT;
2367
2368	if (time_before(jiffies, expires)) {
2369	mod_timer(&pool->idle_timer, expires);
2370	break;
2371	}
2372
2373	set_worker_dying(worker, &cull_list);
2374	}
2375
2376	raw_spin_unlock_irq(&pool->lock);
2377	wake_dying_workers(&cull_list);
2378	mutex_unlock(&wq_pool_attach_mutex);
2379	}
2380
2381	static void send_mayday(struct work_struct *work)
2382	{
2383	struct pool_workqueue *pwq = get_work_pwq(work);
2384	struct workqueue_struct *wq = pwq->wq;
2385
2386	lockdep_assert_held(&wq_mayday_lock);
2387
2388	if (!wq->rescuer)
2389	return;
2390
2391	/* mayday mayday mayday */
2392	if (list_empty(&pwq->mayday_node)) {
2393	/*
2394	* If @pwq is for an unbound wq, its base ref may be put at
2395	* any time due to an attribute change. Pin @pwq until the
2396	* rescuer is done with it.
2397	*/
2398	get_pwq(pwq);
2399	list_add_tail(&pwq->mayday_node, &wq->maydays);
2400	wake_up_process(wq->rescuer->task);
2401	pwq->stats[PWQ_STAT_MAYDAY]++;
2402	}
2403	}
2404
2405	static void pool_mayday_timeout(struct timer_list *t)
2406	{
2407	struct worker_pool *pool = from_timer(pool, t, mayday_timer);
2408	struct work_struct *work;
2409
2410	raw_spin_lock_irq(&pool->lock);
2411	raw_spin_lock(&wq_mayday_lock); /* for wq->maydays */
2412
2413	if (need_to_create_worker(pool)) {
2414	/*
2415	* We've been trying to create a new worker but
2416	* haven't been successful. We might be hitting an
2417	* allocation deadlock. Send distress signals to
2418	* rescuers.
2419	*/
2420	list_for_each_entry(work, &pool->worklist, entry)
2421	send_mayday(work);
2422	}
2423
2424	raw_spin_unlock(&wq_mayday_lock);
2425	raw_spin_unlock_irq(&pool->lock);
2426
2427	mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
2428	}
2429
2430	/**
2431	* maybe_create_worker - create a new worker if necessary
2432	* @pool: pool to create a new worker for
2433	*
2434	* Create a new worker for @pool if necessary. @pool is guaranteed to
2435	* have at least one idle worker on return from this function. If
2436	* creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
2437	* sent to all rescuers with works scheduled on @pool to resolve
2438	* possible allocation deadlock.
2439	*
2440	* On return, need_to_create_worker() is guaranteed to be %false and
2441	* may_start_working() %true.
2442	*
2443	* LOCKING:
2444	* raw_spin_lock_irq(pool->lock) which may be released and regrabbed
2445	* multiple times. Does GFP_KERNEL allocations. Called only from
2446	* manager.
2447	*/
2448	static void maybe_create_worker(struct worker_pool *pool)
2449	__releases(&pool->lock)
2450	__acquires(&pool->lock)
2451	{
2452	restart:
2453	raw_spin_unlock_irq(&pool->lock);
2454
2455	/* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
2456	mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
2457
2458	while (true) {
2459	if (create_worker(pool) \|\| !need_to_create_worker(pool))
2460	break;
2461
2462	schedule_timeout_interruptible(CREATE_COOLDOWN);
2463
2464	if (!need_to_create_worker(pool))
2465	break;
2466	}
2467
2468	del_timer_sync(&pool->mayday_timer);
2469	raw_spin_lock_irq(&pool->lock);
2470	/*
2471	* This is necessary even after a new worker was just successfully
2472	* created as @pool->lock was dropped and the new worker might have
2473	* already become busy.
2474	*/
2475	if (need_to_create_worker(pool))
2476	goto restart;
2477	}
2478
2479	/**
2480	* manage_workers - manage worker pool
2481	* @worker: self
2482	*
2483	* Assume the manager role and manage the worker pool @worker belongs
2484	* to. At any given time, there can be only zero or one manager per
2485	* pool. The exclusion is handled automatically by this function.
2486	*
2487	* The caller can safely start processing works on false return. On
2488	* true return, it's guaranteed that need_to_create_worker() is false
2489	* and may_start_working() is true.
2490	*
2491	* CONTEXT:
2492	* raw_spin_lock_irq(pool->lock) which may be released and regrabbed
2493	* multiple times. Does GFP_KERNEL allocations.
2494	*
2495	* Return:
2496	* %false if the pool doesn't need management and the caller can safely
2497	* start processing works, %true if management function was performed and
2498	* the conditions that the caller verified before calling the function may
2499	* no longer be true.
2500	*/
2501	static bool manage_workers(struct worker *worker)
2502	{
2503	struct worker_pool *pool = worker->pool;
2504
2505	if (pool->flags & POOL_MANAGER_ACTIVE)
2506	return false;
2507
2508	pool->flags \|= POOL_MANAGER_ACTIVE;
2509	pool->manager = worker;
2510
2511	maybe_create_worker(pool);
2512
2513	pool->manager = NULL;
2514	pool->flags &= ~POOL_MANAGER_ACTIVE;
2515	rcuwait_wake_up(&manager_wait);
2516	return true;
2517	}
2518
2519	/**
2520	* process_one_work - process single work
2521	* @worker: self
2522	* @work: work to process
2523	*
2524	* Process @work. This function contains all the logics necessary to
2525	* process a single work including synchronization against and
2526	* interaction with other workers on the same cpu, queueing and
2527	* flushing. As long as context requirement is met, any worker can
2528	* call this function to process a work.
2529	*
2530	* CONTEXT:
2531	* raw_spin_lock_irq(pool->lock) which is released and regrabbed.
2532	*/
2533	static void process_one_work(struct worker worker, struct work_struct work)
2534	__releases(&pool->lock)
2535	__acquires(&pool->lock)
2536	{
2537	struct pool_workqueue *pwq = get_work_pwq(work);
2538	struct worker_pool *pool = worker->pool;
2539	unsigned long work_data;
2540	#ifdef CONFIG_LOCKDEP
2541	/*
2542	* It is permissible to free the struct work_struct from
2543	* inside the function that is called from it, this we need to
2544	* take into account for lockdep too. To avoid bogus "held
2545	* lock freed" warnings as well as problems when looking into
2546	* work->lockdep_map, make a copy and use that here.
2547	*/
2548	struct lockdep_map lockdep_map;
2549
2550	lockdep_copy_map(&lockdep_map, &work->lockdep_map);
2551	#endif
2552	/* ensure we're on the correct CPU */
2553	WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
2554	raw_smp_processor_id() != pool->cpu);
2555
2556	/* claim and dequeue */
2557	debug_work_deactivate(work);
2558	hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work);
2559	worker->current_work = work;
2560	worker->current_func = work->func;
2561	worker->current_pwq = pwq;
2562	worker->current_at = worker->task->se.sum_exec_runtime;
2563	work_data = *work_data_bits(work);
2564	worker->current_color = get_work_color(work_data);
2565
2566	/*
2567	* Record wq name for cmdline and debug reporting, may get
2568	* overridden through set_worker_desc().
2569	*/
2570	strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN);
2571
2572	list_del_init(&work->entry);
2573
2574	/*
2575	* CPU intensive works don't participate in concurrency management.
2576	* They're the scheduler's responsibility. This takes @worker out
2577	* of concurrency management and the next code block will chain
2578	* execution of the pending work items.
2579	*/
2580	if (unlikely(pwq->wq->flags & WQ_CPU_INTENSIVE))
2581	worker_set_flags(worker, WORKER_CPU_INTENSIVE);
2582
2583	/*
2584	* Kick @pool if necessary. It's always noop for per-cpu worker pools
2585	* since nr_running would always be >= 1 at this point. This is used to
2586	* chain execution of the pending work items for WORKER_NOT_RUNNING
2587	* workers such as the UNBOUND and CPU_INTENSIVE ones.
2588	*/
2589	kick_pool(pool);
2590
2591	/*
2592	* Record the last pool and clear PENDING which should be the last
2593	* update to @work. Also, do this inside @pool->lock so that
2594	* PENDING and queued state changes happen together while IRQ is
2595	* disabled.
2596	*/
2597	set_work_pool_and_clear_pending(work, pool->id);
2598
2599	pwq->stats[PWQ_STAT_STARTED]++;
2600	raw_spin_unlock_irq(&pool->lock);
2601
2602	lock_map_acquire(&pwq->wq->lockdep_map);
2603	lock_map_acquire(&lockdep_map);
2604	/*
2605	* Strictly speaking we should mark the invariant state without holding
2606	* any locks, that is, before these two lock_map_acquire()'s.
2607	*
2608	* However, that would result in:
2609	*
2610	* A(W1)
2611	* WFC(C)
2612	* A(W1)
2613	* C(C)
2614	*
2615	* Which would create W1->C->W1 dependencies, even though there is no
2616	* actual deadlock possible. There are two solutions, using a
2617	* read-recursive acquire on the work(queue) 'locks', but this will then
2618	* hit the lockdep limitation on recursive locks, or simply discard
2619	* these locks.
2620	*
2621	* AFAICT there is no possible deadlock scenario between the
2622	* flush_work() and complete() primitives (except for single-threaded
2623	* workqueues), so hiding them isn't a problem.
2624	*/
2625	lockdep_invariant_state(true);
2626	trace_workqueue_execute_start(work);
2627	worker->current_func(work);
2628	/*
2629	* While we must be careful to not use "work" after this, the trace
2630	* point will only record its address.
2631	*/
2632	trace_workqueue_execute_end(work, worker->current_func);
2633	pwq->stats[PWQ_STAT_COMPLETED]++;
2634	lock_map_release(&lockdep_map);
2635	lock_map_release(&pwq->wq->lockdep_map);
2636
2637	if (unlikely(in_atomic() \|\| lockdep_depth(current) > 0)) {
2638	pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
2639	" last function: %ps\n",
2640	current->comm, preempt_count(), task_pid_nr(current),
2641	worker->current_func);
2642	debug_show_held_locks(current);
2643	dump_stack();
2644	}
2645
2646	/*
2647	* The following prevents a kworker from hogging CPU on !PREEMPTION
2648	* kernels, where a requeueing work item waiting for something to
2649	* happen could deadlock with stop_machine as such work item could
2650	* indefinitely requeue itself while all other CPUs are trapped in
2651	* stop_machine. At the same time, report a quiescent RCU state so
2652	* the same condition doesn't freeze RCU.
2653	*/
2654	cond_resched();
2655
2656	raw_spin_lock_irq(&pool->lock);
2657
2658	/*
2659	* In addition to %WQ_CPU_INTENSIVE, @worker may also have been marked
2660	* CPU intensive by wq_worker_tick() if @work hogged CPU longer than
2661	* wq_cpu_intensive_thresh_us. Clear it.
2662	*/
2663	worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
2664
2665	/* tag the worker for identification in schedule() */
2666	worker->last_func = worker->current_func;
2667
2668	/* we're done with it, release */
2669	hash_del(&worker->hentry);
2670	worker->current_work = NULL;
2671	worker->current_func = NULL;
2672	worker->current_pwq = NULL;
2673	worker->current_color = INT_MAX;
2674	pwq_dec_nr_in_flight(pwq, work_data);
2675	}
2676
2677	/**
2678	* process_scheduled_works - process scheduled works
2679	* @worker: self
2680	*
2681	* Process all scheduled works. Please note that the scheduled list
2682	* may change while processing a work, so this function repeatedly
2683	* fetches a work from the top and executes it.
2684	*
2685	* CONTEXT:
2686	* raw_spin_lock_irq(pool->lock) which may be released and regrabbed
2687	* multiple times.
2688	*/
2689	static void process_scheduled_works(struct worker *worker)
2690	{
2691	struct work_struct *work;
2692	bool first = true;
2693
2694	while ((work = list_first_entry_or_null(&worker->scheduled,
2695	struct work_struct, entry))) {
2696	if (first) {
2697	worker->pool->watchdog_ts = jiffies;
2698	first = false;
2699	}
2700	process_one_work(worker, work);
2701	}
2702	}
2703
2704	static void set_pf_worker(bool val)
2705	{
2706	mutex_lock(&wq_pool_attach_mutex);
2707	if (val)
2708	current->flags \|= PF_WQ_WORKER;
2709	else
2710	current->flags &= ~PF_WQ_WORKER;
2711	mutex_unlock(&wq_pool_attach_mutex);
2712	}
2713
2714	/**
2715	* worker_thread - the worker thread function
2716	* @__worker: self
2717	*
2718	* The worker thread function. All workers belong to a worker_pool -
2719	* either a per-cpu one or dynamic unbound one. These workers process all
2720	* work items regardless of their specific target workqueue. The only
2721	* exception is work items which belong to workqueues with a rescuer which
2722	* will be explained in rescuer_thread().
2723	*
2724	* Return: 0
2725	*/
2726	static int worker_thread(void *__worker)
2727	{
2728	struct worker *worker = __worker;
2729	struct worker_pool *pool = worker->pool;
2730
2731	/* tell the scheduler that this is a workqueue worker */
2732	set_pf_worker(true);
2733	woke_up:
2734	raw_spin_lock_irq(&pool->lock);
2735
2736	/* am I supposed to die? */
2737	if (unlikely(worker->flags & WORKER_DIE)) {
2738	raw_spin_unlock_irq(&pool->lock);
2739	set_pf_worker(false);
2740
2741	set_task_comm(worker->task, "kworker/dying");
2742	ida_free(&pool->worker_ida, worker->id);
2743	worker_detach_from_pool(worker);
2744	WARN_ON_ONCE(!list_empty(&worker->entry));
2745	kfree(worker);
2746	return 0;
2747	}
2748
2749	worker_leave_idle(worker);
2750	recheck:
2751	/* no more worker necessary? */
2752	if (!need_more_worker(pool))
2753	goto sleep;
2754
2755	/* do we need to manage? */
2756	if (unlikely(!may_start_working(pool)) && manage_workers(worker))
2757	goto recheck;
2758
2759	/*
2760	* ->scheduled list can only be filled while a worker is
2761	* preparing to process a work or actually processing it.
2762	* Make sure nobody diddled with it while I was sleeping.
2763	*/
2764	WARN_ON_ONCE(!list_empty(&worker->scheduled));
2765
2766	/*
2767	* Finish PREP stage. We're guaranteed to have at least one idle
2768	* worker or that someone else has already assumed the manager
2769	* role. This is where @worker starts participating in concurrency
2770	* management if applicable and concurrency management is restored
2771	* after being rebound. See rebind_workers() for details.
2772	*/
2773	worker_clr_flags(worker, WORKER_PREP \| WORKER_REBOUND);
2774
2775	do {
2776	struct work_struct *work =
2777	list_first_entry(&pool->worklist,
2778	struct work_struct, entry);
2779
2780	if (assign_work(work, worker, NULL))
2781	process_scheduled_works(worker);
2782	} while (keep_working(pool));
2783
2784	worker_set_flags(worker, WORKER_PREP);
2785	sleep:
2786	/*
2787	* pool->lock is held and there's no work to process and no need to
2788	* manage, sleep. Workers are woken up only while holding
2789	* pool->lock or from local cpu, so setting the current state
2790	* before releasing pool->lock is enough to prevent losing any
2791	* event.
2792	*/
2793	worker_enter_idle(worker);
2794	__set_current_state(TASK_IDLE);
2795	raw_spin_unlock_irq(&pool->lock);
2796	schedule();
2797	goto woke_up;
2798	}
2799
2800	/**
2801	* rescuer_thread - the rescuer thread function
2802	* @__rescuer: self
2803	*
2804	* Workqueue rescuer thread function. There's one rescuer for each
2805	* workqueue which has WQ_MEM_RECLAIM set.
2806	*
2807	* Regular work processing on a pool may block trying to create a new
2808	* worker which uses GFP_KERNEL allocation which has slight chance of
2809	* developing into deadlock if some works currently on the same queue
2810	* need to be processed to satisfy the GFP_KERNEL allocation. This is
2811	* the problem rescuer solves.
2812	*
2813	* When such condition is possible, the pool summons rescuers of all
2814	* workqueues which have works queued on the pool and let them process
2815	* those works so that forward progress can be guaranteed.
2816	*
2817	* This should happen rarely.
2818	*
2819	* Return: 0
2820	*/
2821	static int rescuer_thread(void *__rescuer)
2822	{
2823	struct worker *rescuer = __rescuer;
2824	struct workqueue_struct *wq = rescuer->rescue_wq;
2825	bool should_stop;
2826
2827	set_user_nice(current, RESCUER_NICE_LEVEL);
2828
2829	/*
2830	* Mark rescuer as worker too. As WORKER_PREP is never cleared, it
2831	* doesn't participate in concurrency management.
2832	*/
2833	set_pf_worker(true);
2834	repeat:
2835	set_current_state(TASK_IDLE);
2836
2837	/*
2838	* By the time the rescuer is requested to stop, the workqueue
2839	* shouldn't have any work pending, but @wq->maydays may still have
2840	* pwq(s) queued. This can happen by non-rescuer workers consuming
2841	* all the work items before the rescuer got to them. Go through
2842	* @wq->maydays processing before acting on should_stop so that the
2843	* list is always empty on exit.
2844	*/
2845	should_stop = kthread_should_stop();
2846
2847	/* see whether any pwq is asking for help */
2848	raw_spin_lock_irq(&wq_mayday_lock);
2849
2850	while (!list_empty(&wq->maydays)) {
2851	struct pool_workqueue *pwq = list_first_entry(&wq->maydays,
2852	struct pool_workqueue, mayday_node);
2853	struct worker_pool *pool = pwq->pool;
2854	struct work_struct work, n;
2855
2856	__set_current_state(TASK_RUNNING);
2857	list_del_init(&pwq->mayday_node);
2858
2859	raw_spin_unlock_irq(&wq_mayday_lock);
2860
2861	worker_attach_to_pool(rescuer, pool);
2862
2863	raw_spin_lock_irq(&pool->lock);
2864
2865	/*
2866	* Slurp in all works issued via this workqueue and
2867	* process'em.
2868	*/
2869	WARN_ON_ONCE(!list_empty(&rescuer->scheduled));
2870	list_for_each_entry_safe(work, n, &pool->worklist, entry) {
2871	if (get_work_pwq(work) == pwq &&
2872	assign_work(work, rescuer, &n))
2873	pwq->stats[PWQ_STAT_RESCUED]++;
2874	}
2875
2876	if (!list_empty(&rescuer->scheduled)) {
2877	process_scheduled_works(rescuer);
2878
2879	/*
2880	* The above execution of rescued work items could
2881	* have created more to rescue through
2882	* pwq_activate_first_inactive() or chained
2883	* queueing. Let's put @pwq back on mayday list so
2884	* that such back-to-back work items, which may be
2885	* being used to relieve memory pressure, don't
2886	* incur MAYDAY_INTERVAL delay inbetween.
2887	*/
2888	if (pwq->nr_active && need_to_create_worker(pool)) {
2889	raw_spin_lock(&wq_mayday_lock);
2890	/*
2891	* Queue iff we aren't racing destruction
2892	* and somebody else hasn't queued it already.
2893	*/
2894	if (wq->rescuer && list_empty(&pwq->mayday_node)) {
2895	get_pwq(pwq);
2896	list_add_tail(&pwq->mayday_node, &wq->maydays);
2897	}
2898	raw_spin_unlock(&wq_mayday_lock);
2899	}
2900	}
2901
2902	/*
2903	* Put the reference grabbed by send_mayday(). @pool won't
2904	* go away while we're still attached to it.
2905	*/
2906	put_pwq(pwq);
2907
2908	/*
2909	* Leave this pool. Notify regular workers; otherwise, we end up
2910	* with 0 concurrency and stalling the execution.
2911	*/
2912	kick_pool(pool);
2913
2914	raw_spin_unlock_irq(&pool->lock);
2915
2916	worker_detach_from_pool(rescuer);
2917
2918	raw_spin_lock_irq(&wq_mayday_lock);
2919	}
2920
2921	raw_spin_unlock_irq(&wq_mayday_lock);
2922
2923	if (should_stop) {
2924	__set_current_state(TASK_RUNNING);
2925	set_pf_worker(false);
2926	return 0;
2927	}
2928
2929	/* rescuers should never participate in concurrency management */
2930	WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING));
2931	schedule();
2932	goto repeat;
2933	}
2934
2935	/**
2936	* check_flush_dependency - check for flush dependency sanity
2937	* @target_wq: workqueue being flushed
2938	* @target_work: work item being flushed (NULL for workqueue flushes)
2939	*
2940	* %current is trying to flush the whole @target_wq or @target_work on it.
2941	* If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not
2942	* reclaiming memory or running on a workqueue which doesn't have
2943	* %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to
2944	* a deadlock.
2945	*/
2946	static void check_flush_dependency(struct workqueue_struct *target_wq,
2947	struct work_struct *target_work)
2948	{
2949	work_func_t target_func = target_work ? target_work->func : NULL;
2950	struct worker *worker;
2951
2952	if (target_wq->flags & WQ_MEM_RECLAIM)
2953	return;
2954
2955	worker = current_wq_worker();
2956
2957	WARN_ONCE(current->flags & PF_MEMALLOC,
2958	"workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps",
2959	current->pid, current->comm, target_wq->name, target_func);
2960	WARN_ONCE(worker && ((worker->current_pwq->wq->flags &
2961	(WQ_MEM_RECLAIM \| __WQ_LEGACY)) == WQ_MEM_RECLAIM),
2962	"workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps",
2963	worker->current_pwq->wq->name, worker->current_func,
2964	target_wq->name, target_func);
2965	}
2966
2967	struct wq_barrier {
2968	struct work_struct work;
2969	struct completion done;
2970	struct task_struct task; / purely informational */
2971	};
2972
2973	static void wq_barrier_func(struct work_struct *work)
2974	{
2975	struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
2976	complete(&barr->done);
2977	}
2978
2979	/**
2980	* insert_wq_barrier - insert a barrier work
2981	* @pwq: pwq to insert barrier into
2982	* @barr: wq_barrier to insert
2983	* @target: target work to attach @barr to
2984	* @worker: worker currently executing @target, NULL if @target is not executing
2985	*
2986	* @barr is linked to @target such that @barr is completed only after
2987	* @target finishes execution. Please note that the ordering
2988	* guarantee is observed only with respect to @target and on the local
2989	* cpu.
2990	*
2991	* Currently, a queued barrier can't be canceled. This is because
2992	* try_to_grab_pending() can't determine whether the work to be
2993	* grabbed is at the head of the queue and thus can't clear LINKED
2994	* flag of the previous work while there must be a valid next work
2995	* after a work with LINKED flag set.
2996	*
2997	* Note that when @worker is non-NULL, @target may be modified
2998	* underneath us, so we can't reliably determine pwq from @target.
2999	*
3000	* CONTEXT:
3001	* raw_spin_lock_irq(pool->lock).
3002	*/
3003	static void insert_wq_barrier(struct pool_workqueue *pwq,
3004	struct wq_barrier *barr,
3005	struct work_struct target, struct worker worker)
3006	{
3007	unsigned int work_flags = 0;
3008	unsigned int work_color;
3009	struct list_head *head;
3010
3011	/*
3012	* debugobject calls are safe here even with pool->lock locked
3013	* as we know for sure that this will not trigger any of the
3014	* checks and call back into the fixup functions where we
3015	* might deadlock.
3016	*/
3017	INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
3018	__set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
3019
3020	init_completion_map(&barr->done, &target->lockdep_map);
3021
3022	barr->task = current;
3023
3024	/* The barrier work item does not participate in pwq->nr_active. */
3025	work_flags \|= WORK_STRUCT_INACTIVE;
3026
3027	/*
3028	* If @target is currently being executed, schedule the
3029	* barrier to the worker; otherwise, put it after @target.
3030	*/
3031	if (worker) {
3032	head = worker->scheduled.next;
3033	work_color = worker->current_color;
3034	} else {
3035	unsigned long *bits = work_data_bits(target);
3036
3037	head = target->entry.next;
3038	/* there can already be other linked works, inherit and set */
3039	work_flags \|= *bits & WORK_STRUCT_LINKED;
3040	work_color = get_work_color(*bits);
3041	__set_bit(WORK_STRUCT_LINKED_BIT, bits);
3042	}
3043
3044	pwq->nr_in_flight[work_color]++;
3045	work_flags \|= work_color_to_flags(work_color);
3046
3047	insert_work(pwq, &barr->work, head, work_flags);
3048	}
3049
3050	/**
3051	* flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
3052	* @wq: workqueue being flushed
3053	* @flush_color: new flush color, < 0 for no-op
3054	* @work_color: new work color, < 0 for no-op
3055	*
3056	* Prepare pwqs for workqueue flushing.
3057	*
3058	* If @flush_color is non-negative, flush_color on all pwqs should be
3059	* -1. If no pwq has in-flight commands at the specified color, all
3060	* pwq->flush_color's stay at -1 and %false is returned. If any pwq
3061	* has in flight commands, its pwq->flush_color is set to
3062	* @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
3063	* wakeup logic is armed and %true is returned.
3064	*
3065	* The caller should have initialized @wq->first_flusher prior to
3066	* calling this function with non-negative @flush_color. If
3067	* @flush_color is negative, no flush color update is done and %false
3068	* is returned.
3069	*
3070	* If @work_color is non-negative, all pwqs should have the same
3071	* work_color which is previous to @work_color and all will be
3072	* advanced to @work_color.
3073	*
3074	* CONTEXT:
3075	* mutex_lock(wq->mutex).
3076	*
3077	* Return:
3078	* %true if @flush_color >= 0 and there's something to flush. %false
3079	* otherwise.
3080	*/
3081	static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq,
3082	int flush_color, int work_color)
3083	{
3084	bool wait = false;
3085	struct pool_workqueue *pwq;
3086
3087	if (flush_color >= 0) {
3088	WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush));
3089	atomic_set(&wq->nr_pwqs_to_flush, 1);
3090	}
3091
3092	for_each_pwq(pwq, wq) {
3093	struct worker_pool *pool = pwq->pool;
3094
3095	raw_spin_lock_irq(&pool->lock);
3096
3097	if (flush_color >= 0) {
3098	WARN_ON_ONCE(pwq->flush_color != -1);
3099
3100	if (pwq->nr_in_flight[flush_color]) {
3101	pwq->flush_color = flush_color;
3102	atomic_inc(&wq->nr_pwqs_to_flush);
3103	wait = true;
3104	}
3105	}
3106
3107	if (work_color >= 0) {
3108	WARN_ON_ONCE(work_color != work_next_color(pwq->work_color));
3109	pwq->work_color = work_color;
3110	}
3111
3112	raw_spin_unlock_irq(&pool->lock);
3113	}
3114
3115	if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush))
3116	complete(&wq->first_flusher->done);
3117
3118	return wait;
3119	}
3120
3121	/**
3122	* __flush_workqueue - ensure that any scheduled work has run to completion.
3123	* @wq: workqueue to flush
3124	*
3125	* This function sleeps until all work items which were queued on entry
3126	* have finished execution, but it is not livelocked by new incoming ones.
3127	*/
3128	void __flush_workqueue(struct workqueue_struct *wq)
3129	{
3130	struct wq_flusher this_flusher = {
3131	.list = LIST_HEAD_INIT(this_flusher.list),
3132	.flush_color = -1,
3133	.done = COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher.done, wq->lockdep_map),
3134	};
3135	int next_color;
3136
3137	if (WARN_ON(!wq_online))
3138	return;
3139
3140	lock_map_acquire(&wq->lockdep_map);
3141	lock_map_release(&wq->lockdep_map);
3142
3143	mutex_lock(&wq->mutex);
3144
3145	/*
3146	* Start-to-wait phase
3147	*/
3148	next_color = work_next_color(wq->work_color);
3149
3150	if (next_color != wq->flush_color) {
3151	/*
3152	* Color space is not full. The current work_color
3153	* becomes our flush_color and work_color is advanced
3154	* by one.
3155	*/
3156	WARN_ON_ONCE(!list_empty(&wq->flusher_overflow));
3157	this_flusher.flush_color = wq->work_color;
3158	wq->work_color = next_color;
3159
3160	if (!wq->first_flusher) {
3161	/* no flush in progress, become the first flusher */
3162	WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
3163
3164	wq->first_flusher = &this_flusher;
3165
3166	if (!flush_workqueue_prep_pwqs(wq, wq->flush_color,
3167	wq->work_color)) {
3168	/* nothing to flush, done */
3169	wq->flush_color = next_color;
3170	wq->first_flusher = NULL;
3171	goto out_unlock;
3172	}
3173	} else {
3174	/* wait in queue */
3175	WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color);
3176	list_add_tail(&this_flusher.list, &wq->flusher_queue);
3177	flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
3178	}
3179	} else {
3180	/*
3181	* Oops, color space is full, wait on overflow queue.
3182	* The next flush completion will assign us
3183	* flush_color and transfer to flusher_queue.
3184	*/
3185	list_add_tail(&this_flusher.list, &wq->flusher_overflow);
3186	}
3187
3188	check_flush_dependency(wq, NULL);
3189
3190	mutex_unlock(&wq->mutex);
3191
3192	wait_for_completion(&this_flusher.done);
3193
3194	/*
3195	* Wake-up-and-cascade phase
3196	*
3197	* First flushers are responsible for cascading flushes and
3198	* handling overflow. Non-first flushers can simply return.
3199	*/
3200	if (READ_ONCE(wq->first_flusher) != &this_flusher)
3201	return;
3202
3203	mutex_lock(&wq->mutex);
3204
3205	/* we might have raced, check again with mutex held */
3206	if (wq->first_flusher != &this_flusher)
3207	goto out_unlock;
3208
3209	WRITE_ONCE(wq->first_flusher, NULL);
3210
3211	WARN_ON_ONCE(!list_empty(&this_flusher.list));
3212	WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
3213
3214	while (true) {
3215	struct wq_flusher next, tmp;
3216
3217	/* complete all the flushers sharing the current flush color */
3218	list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
3219	if (next->flush_color != wq->flush_color)
3220	break;
3221	list_del_init(&next->list);
3222	complete(&next->done);
3223	}
3224
3225	WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) &&
3226	wq->flush_color != work_next_color(wq->work_color));
3227
3228	/* this flush_color is finished, advance by one */
3229	wq->flush_color = work_next_color(wq->flush_color);
3230
3231	/* one color has been freed, handle overflow queue */
3232	if (!list_empty(&wq->flusher_overflow)) {
3233	/*
3234	* Assign the same color to all overflowed
3235	* flushers, advance work_color and append to
3236	* flusher_queue. This is the start-to-wait
3237	* phase for these overflowed flushers.
3238	*/
3239	list_for_each_entry(tmp, &wq->flusher_overflow, list)
3240	tmp->flush_color = wq->work_color;
3241
3242	wq->work_color = work_next_color(wq->work_color);
3243
3244	list_splice_tail_init(&wq->flusher_overflow,
3245	&wq->flusher_queue);
3246	flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
3247	}
3248
3249	if (list_empty(&wq->flusher_queue)) {
3250	WARN_ON_ONCE(wq->flush_color != wq->work_color);
3251	break;
3252	}
3253
3254	/*
3255	* Need to flush more colors. Make the next flusher
3256	* the new first flusher and arm pwqs.
3257	*/
3258	WARN_ON_ONCE(wq->flush_color == wq->work_color);
3259	WARN_ON_ONCE(wq->flush_color != next->flush_color);
3260
3261	list_del_init(&next->list);
3262	wq->first_flusher = next;
3263
3264	if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1))
3265	break;
3266
3267	/*
3268	* Meh... this color is already done, clear first
3269	* flusher and repeat cascading.
3270	*/
3271	wq->first_flusher = NULL;
3272	}
3273
3274	out_unlock:
3275	mutex_unlock(&wq->mutex);
3276	}
3277	EXPORT_SYMBOL(__flush_workqueue);
3278
3279	/**
3280	* drain_workqueue - drain a workqueue
3281	* @wq: workqueue to drain
3282	*
3283	* Wait until the workqueue becomes empty. While draining is in progress,
3284	* only chain queueing is allowed. IOW, only currently pending or running
3285	* work items on @wq can queue further work items on it. @wq is flushed
3286	* repeatedly until it becomes empty. The number of flushing is determined
3287	* by the depth of chaining and should be relatively short. Whine if it
3288	* takes too long.
3289	*/
3290	void drain_workqueue(struct workqueue_struct *wq)
3291	{
3292	unsigned int flush_cnt = 0;
3293	struct pool_workqueue *pwq;
3294
3295	/*
3296	* __queue_work() needs to test whether there are drainers, is much
3297	* hotter than drain_workqueue() and already looks at @wq->flags.
3298	* Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
3299	*/
3300	mutex_lock(&wq->mutex);
3301	if (!wq->nr_drainers++)
3302	wq->flags \|= __WQ_DRAINING;
3303	mutex_unlock(&wq->mutex);
3304	reflush:
3305	__flush_workqueue(wq);
3306
3307	mutex_lock(&wq->mutex);
3308
3309	for_each_pwq(pwq, wq) {
3310	bool drained;
3311
3312	raw_spin_lock_irq(&pwq->pool->lock);
3313	drained = !pwq->nr_active && list_empty(&pwq->inactive_works);
3314	raw_spin_unlock_irq(&pwq->pool->lock);
3315
3316	if (drained)
3317	continue;
3318
3319	if (++flush_cnt == 10 \|\|
3320	(flush_cnt % 100 == 0 && flush_cnt <= 1000))
3321	pr_warn("workqueue %s: %s() isn't complete after %u tries\n",
3322	wq->name, __func__, flush_cnt);
3323
3324	mutex_unlock(&wq->mutex);
3325	goto reflush;
3326	}
3327
3328	if (!--wq->nr_drainers)
3329	wq->flags &= ~__WQ_DRAINING;
3330	mutex_unlock(&wq->mutex);
3331	}
3332	EXPORT_SYMBOL_GPL(drain_workqueue);
3333
3334	static bool start_flush_work(struct work_struct work, struct wq_barrier barr,
3335	bool from_cancel)
3336	{
3337	struct worker *worker = NULL;
3338	struct worker_pool *pool;
3339	struct pool_workqueue *pwq;
3340
3341	might_sleep();
3342
3343	rcu_read_lock();
3344	pool = get_work_pool(work);
3345	if (!pool) {
3346	rcu_read_unlock();
3347	return false;
3348	}
3349
3350	raw_spin_lock_irq(&pool->lock);
3351	/* see the comment in try_to_grab_pending() with the same code */
3352	pwq = get_work_pwq(work);
3353	if (pwq) {
3354	if (unlikely(pwq->pool != pool))
3355	goto already_gone;
3356	} else {
3357	worker = find_worker_executing_work(pool, work);
3358	if (!worker)
3359	goto already_gone;
3360	pwq = worker->current_pwq;
3361	}
3362
3363	check_flush_dependency(pwq->wq, work);
3364
3365	insert_wq_barrier(pwq, barr, work, worker);
3366	raw_spin_unlock_irq(&pool->lock);
3367
3368	/*
3369	* Force a lock recursion deadlock when using flush_work() inside a
3370	* single-threaded or rescuer equipped workqueue.
3371	*
3372	* For single threaded workqueues the deadlock happens when the work
3373	* is after the work issuing the flush_work(). For rescuer equipped
3374	* workqueues the deadlock happens when the rescuer stalls, blocking
3375	* forward progress.
3376	*/
3377	if (!from_cancel &&
3378	(pwq->wq->saved_max_active == 1 \|\| pwq->wq->rescuer)) {
3379	lock_map_acquire(&pwq->wq->lockdep_map);
3380	lock_map_release(&pwq->wq->lockdep_map);
3381	}
3382	rcu_read_unlock();
3383	return true;
3384	already_gone:
3385	raw_spin_unlock_irq(&pool->lock);
3386	rcu_read_unlock();
3387	return false;
3388	}
3389
3390	static bool __flush_work(struct work_struct *work, bool from_cancel)
3391	{
3392	struct wq_barrier barr;
3393
3394	if (WARN_ON(!wq_online))
3395	return false;
3396
3397	if (WARN_ON(!work->func))
3398	return false;
3399
3400	lock_map_acquire(&work->lockdep_map);
3401	lock_map_release(&work->lockdep_map);
3402
3403	if (start_flush_work(work, &barr, from_cancel)) {
3404	wait_for_completion(&barr.done);
3405	destroy_work_on_stack(&barr.work);
3406	return true;
3407	} else {
3408	return false;
3409	}
3410	}
3411
3412	/**
3413	* flush_work - wait for a work to finish executing the last queueing instance
3414	* @work: the work to flush
3415	*
3416	* Wait until @work has finished execution. @work is guaranteed to be idle
3417	* on return if it hasn't been requeued since flush started.
3418	*
3419	* Return:
3420	* %true if flush_work() waited for the work to finish execution,
3421	* %false if it was already idle.
3422	*/
3423	bool flush_work(struct work_struct *work)
3424	{
3425	return __flush_work(work, false);
3426	}
3427	EXPORT_SYMBOL_GPL(flush_work);
3428
3429	struct cwt_wait {
3430	wait_queue_entry_t wait;
3431	struct work_struct *work;
3432	};
3433
3434	static int cwt_wakefn(wait_queue_entry_t wait, unsigned mode, int sync, void key)
3435	{
3436	struct cwt_wait *cwait = container_of(wait, struct cwt_wait, wait);
3437
3438	if (cwait->work != key)
3439	return 0;
3440	return autoremove_wake_function(wait, mode, sync, key);
3441	}
3442
3443	static bool __cancel_work_timer(struct work_struct *work, bool is_dwork)
3444	{
3445	static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq);
3446	unsigned long flags;
3447	int ret;
3448
3449	do {
3450	ret = try_to_grab_pending(work, is_dwork, &flags);
3451	/*
3452	* If someone else is already canceling, wait for it to
3453	* finish. flush_work() doesn't work for PREEMPT_NONE
3454	* because we may get scheduled between @work's completion
3455	* and the other canceling task resuming and clearing
3456	* CANCELING - flush_work() will return false immediately
3457	* as @work is no longer busy, try_to_grab_pending() will
3458	* return -ENOENT as @work is still being canceled and the
3459	* other canceling task won't be able to clear CANCELING as
3460	* we're hogging the CPU.
3461	*
3462	* Let's wait for completion using a waitqueue. As this
3463	* may lead to the thundering herd problem, use a custom
3464	* wake function which matches @work along with exclusive
3465	* wait and wakeup.
3466	*/
3467	if (unlikely(ret == -ENOENT)) {
3468	struct cwt_wait cwait;
3469
3470	init_wait(&cwait.wait);
3471	cwait.wait.func = cwt_wakefn;
3472	cwait.work = work;
3473
3474	prepare_to_wait_exclusive(&cancel_waitq, &cwait.wait,
3475	TASK_UNINTERRUPTIBLE);
3476	if (work_is_canceling(work))
3477	schedule();
3478	finish_wait(&cancel_waitq, &cwait.wait);
3479	}
3480	} while (unlikely(ret < 0));
3481
3482	/* tell other tasks trying to grab @work to back off */
3483	mark_work_canceling(work);
3484	local_irq_restore(flags);
3485
3486	/*
3487	* This allows canceling during early boot. We know that @work
3488	* isn't executing.
3489	*/
3490	if (wq_online)
3491	__flush_work(work, true);
3492
3493	clear_work_data(work);
3494
3495	/*
3496	* Paired with prepare_to_wait() above so that either
3497	* waitqueue_active() is visible here or !work_is_canceling() is
3498	* visible there.
3499	*/
3500	smp_mb();
3501	if (waitqueue_active(&cancel_waitq))
3502	__wake_up(&cancel_waitq, TASK_NORMAL, 1, work);
3503
3504	return ret;
3505	}
3506
3507	/**
3508	* cancel_work_sync - cancel a work and wait for it to finish
3509	* @work: the work to cancel
3510	*
3511	* Cancel @work and wait for its execution to finish. This function
3512	* can be used even if the work re-queues itself or migrates to
3513	* another workqueue. On return from this function, @work is
3514	* guaranteed to be not pending or executing on any CPU.
3515	*
3516	* cancel_work_sync(&delayed_work->work) must not be used for
3517	* delayed_work's. Use cancel_delayed_work_sync() instead.
3518	*
3519	* The caller must ensure that the workqueue on which @work was last
3520	* queued can't be destroyed before this function returns.
3521	*
3522	* Return:
3523	* %true if @work was pending, %false otherwise.
3524	*/
3525	bool cancel_work_sync(struct work_struct *work)
3526	{
3527	return __cancel_work_timer(work, false);
3528	}
3529	EXPORT_SYMBOL_GPL(cancel_work_sync);
3530
3531	/**
3532	* flush_delayed_work - wait for a dwork to finish executing the last queueing
3533	* @dwork: the delayed work to flush
3534	*
3535	* Delayed timer is cancelled and the pending work is queued for
3536	* immediate execution. Like flush_work(), this function only
3537	* considers the last queueing instance of @dwork.
3538	*
3539	* Return:
3540	* %true if flush_work() waited for the work to finish execution,
3541	* %false if it was already idle.
3542	*/
3543	bool flush_delayed_work(struct delayed_work *dwork)
3544	{
3545	local_irq_disable();
3546	if (del_timer_sync(&dwork->timer))
3547	__queue_work(dwork->cpu, dwork->wq, &dwork->work);
3548	local_irq_enable();
3549	return flush_work(&dwork->work);
3550	}
3551	EXPORT_SYMBOL(flush_delayed_work);
3552
3553	/**
3554	* flush_rcu_work - wait for a rwork to finish executing the last queueing
3555	* @rwork: the rcu work to flush
3556	*
3557	* Return:
3558	* %true if flush_rcu_work() waited for the work to finish execution,
3559	* %false if it was already idle.
3560	*/
3561	bool flush_rcu_work(struct rcu_work *rwork)
3562	{
3563	if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) {
3564	rcu_barrier();
3565	flush_work(&rwork->work);
3566	return true;
3567	} else {
3568	return flush_work(&rwork->work);
3569	}
3570	}
3571	EXPORT_SYMBOL(flush_rcu_work);
3572
3573	static bool __cancel_work(struct work_struct *work, bool is_dwork)
3574	{
3575	unsigned long flags;
3576	int ret;
3577
3578	do {
3579	ret = try_to_grab_pending(work, is_dwork, &flags);
3580	} while (unlikely(ret == -EAGAIN));
3581
3582	if (unlikely(ret < 0))
3583	return false;
3584
3585	set_work_pool_and_clear_pending(work, get_work_pool_id(work));
3586	local_irq_restore(flags);
3587	return ret;
3588	}
3589
3590	/*
3591	* See cancel_delayed_work()
3592	*/
3593	bool cancel_work(struct work_struct *work)
3594	{
3595	return __cancel_work(work, false);
3596	}
3597	EXPORT_SYMBOL(cancel_work);
3598
3599	/**
3600	* cancel_delayed_work - cancel a delayed work
3601	* @dwork: delayed_work to cancel
3602	*
3603	* Kill off a pending delayed_work.
3604	*
3605	* Return: %true if @dwork was pending and canceled; %false if it wasn't
3606	* pending.
3607	*
3608	* Note:
3609	* The work callback function may still be running on return, unless
3610	* it returns %true and the work doesn't re-arm itself. Explicitly flush or
3611	* use cancel_delayed_work_sync() to wait on it.
3612	*
3613	* This function is safe to call from any context including IRQ handler.
3614	*/
3615	bool cancel_delayed_work(struct delayed_work *dwork)
3616	{
3617	return __cancel_work(&dwork->work, true);
3618	}
3619	EXPORT_SYMBOL(cancel_delayed_work);
3620
3621	/**
3622	* cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
3623	* @dwork: the delayed work cancel
3624	*
3625	* This is cancel_work_sync() for delayed works.
3626	*
3627	* Return:
3628	* %true if @dwork was pending, %false otherwise.
3629	*/
3630	bool cancel_delayed_work_sync(struct delayed_work *dwork)
3631	{
3632	return __cancel_work_timer(&dwork->work, true);
3633	}
3634	EXPORT_SYMBOL(cancel_delayed_work_sync);
3635
3636	/**
3637	* schedule_on_each_cpu - execute a function synchronously on each online CPU
3638	* @func: the function to call
3639	*
3640	* schedule_on_each_cpu() executes @func on each online CPU using the
3641	* system workqueue and blocks until all CPUs have completed.
3642	* schedule_on_each_cpu() is very slow.
3643	*
3644	* Return:
3645	* 0 on success, -errno on failure.
3646	*/
3647	int schedule_on_each_cpu(work_func_t func)
3648	{
3649	int cpu;
3650	struct work_struct __percpu *works;
3651
3652	works = alloc_percpu(struct work_struct);
3653	if (!works)
3654	return -ENOMEM;
3655
3656	cpus_read_lock();
3657
3658	for_each_online_cpu(cpu) {
3659	struct work_struct *work = per_cpu_ptr(works, cpu);
3660
3661	INIT_WORK(work, func);
3662	schedule_work_on(cpu, work);
3663	}
3664
3665	for_each_online_cpu(cpu)
3666	flush_work(per_cpu_ptr(works, cpu));
3667
3668	cpus_read_unlock();
3669	free_percpu(works);
3670	return 0;
3671	}
3672
3673	/**
3674	* execute_in_process_context - reliably execute the routine with user context
3675	* @fn: the function to execute
3676	* @ew: guaranteed storage for the execute work structure (must
3677	* be available when the work executes)
3678	*
3679	* Executes the function immediately if process context is available,
3680	* otherwise schedules the function for delayed execution.
3681	*
3682	* Return: 0 - function was executed
3683	* 1 - function was scheduled for execution
3684	*/
3685	int execute_in_process_context(work_func_t fn, struct execute_work *ew)
3686	{
3687	if (!in_interrupt()) {
3688	fn(&ew->work);
3689	return 0;
3690	}
3691
3692	INIT_WORK(&ew->work, fn);
3693	schedule_work(&ew->work);
3694
3695	return 1;
3696	}
3697	EXPORT_SYMBOL_GPL(execute_in_process_context);
3698
3699	/**
3700	* free_workqueue_attrs - free a workqueue_attrs
3701	* @attrs: workqueue_attrs to free
3702	*
3703	* Undo alloc_workqueue_attrs().
3704	*/
3705	void free_workqueue_attrs(struct workqueue_attrs *attrs)
3706	{
3707	if (attrs) {
3708	free_cpumask_var(attrs->cpumask);
3709	free_cpumask_var(attrs->__pod_cpumask);
3710	kfree(attrs);
3711	}
3712	}
3713
3714	/**
3715	* alloc_workqueue_attrs - allocate a workqueue_attrs
3716	*
3717	* Allocate a new workqueue_attrs, initialize with default settings and
3718	* return it.
3719	*
3720	* Return: The allocated new workqueue_attr on success. %NULL on failure.
3721	*/
3722	struct workqueue_attrs *alloc_workqueue_attrs(void)
3723	{
3724	struct workqueue_attrs *attrs;
3725
3726	attrs = kzalloc(sizeof(*attrs), GFP_KERNEL);
3727	if (!attrs)
3728	goto fail;
3729	if (!alloc_cpumask_var(&attrs->cpumask, GFP_KERNEL))
3730	goto fail;
3731	if (!alloc_cpumask_var(&attrs->__pod_cpumask, GFP_KERNEL))
3732	goto fail;
3733
3734	cpumask_copy(attrs->cpumask, cpu_possible_mask);
3735	attrs->affn_scope = WQ_AFFN_DFL;
3736	return attrs;
3737	fail:
3738	free_workqueue_attrs(attrs);
3739	return NULL;
3740	}
3741
3742	static void copy_workqueue_attrs(struct workqueue_attrs *to,
3743	const struct workqueue_attrs *from)
3744	{
3745	to->nice = from->nice;
3746	cpumask_copy(to->cpumask, from->cpumask);
3747	cpumask_copy(to->__pod_cpumask, from->__pod_cpumask);
3748	to->affn_strict = from->affn_strict;
3749
3750	/*
3751	* Unlike hash and equality test, copying shouldn't ignore wq-only
3752	* fields as copying is used for both pool and wq attrs. Instead,
3753	* get_unbound_pool() explicitly clears the fields.
3754	*/
3755	to->affn_scope = from->affn_scope;
3756	to->ordered = from->ordered;
3757	}
3758
3759	/*
3760	* Some attrs fields are workqueue-only. Clear them for worker_pool's. See the
3761	* comments in 'struct workqueue_attrs' definition.
3762	*/
3763	static void wqattrs_clear_for_pool(struct workqueue_attrs *attrs)
3764	{
3765	attrs->affn_scope = WQ_AFFN_NR_TYPES;
3766	attrs->ordered = false;
3767	}
3768
3769	/* hash value of the content of @attr */
3770	static u32 wqattrs_hash(const struct workqueue_attrs *attrs)
3771	{
3772	u32 hash = 0;
3773
3774	hash = jhash_1word(attrs->nice, hash);
3775	hash = jhash(cpumask_bits(attrs->cpumask),
3776	BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
3777	hash = jhash(cpumask_bits(attrs->__pod_cpumask),
3778	BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
3779	hash = jhash_1word(attrs->affn_strict, hash);
3780	return hash;
3781	}
3782
3783	/* content equality test */
3784	static bool wqattrs_equal(const struct workqueue_attrs *a,
3785	const struct workqueue_attrs *b)
3786	{
3787	if (a->nice != b->nice)
3788	return false;
3789	if (!cpumask_equal(a->cpumask, b->cpumask))
3790	return false;
3791	if (!cpumask_equal(a->__pod_cpumask, b->__pod_cpumask))
3792	return false;
3793	if (a->affn_strict != b->affn_strict)
3794	return false;
3795	return true;
3796	}
3797
3798	/* Update @attrs with actually available CPUs */
3799	static void wqattrs_actualize_cpumask(struct workqueue_attrs *attrs,
3800	const cpumask_t *unbound_cpumask)
3801	{
3802	/*
3803	* Calculate the effective CPU mask of @attrs given @unbound_cpumask. If
3804	* @attrs->cpumask doesn't overlap with @unbound_cpumask, we fallback to
3805	* @unbound_cpumask.
3806	*/
3807	cpumask_and(attrs->cpumask, attrs->cpumask, unbound_cpumask);
3808	if (unlikely(cpumask_empty(attrs->cpumask)))
3809	cpumask_copy(attrs->cpumask, unbound_cpumask);
3810	}
3811
3812	/* find wq_pod_type to use for @attrs */
3813	static const struct wq_pod_type *
3814	wqattrs_pod_type(const struct workqueue_attrs *attrs)
3815	{
3816	enum wq_affn_scope scope;
3817	struct wq_pod_type *pt;
3818
3819	/* to synchronize access to wq_affn_dfl */
3820	lockdep_assert_held(&wq_pool_mutex);
3821
3822	if (attrs->affn_scope == WQ_AFFN_DFL)
3823	scope = wq_affn_dfl;
3824	else
3825	scope = attrs->affn_scope;
3826
3827	pt = &wq_pod_types[scope];
3828
3829	if (!WARN_ON_ONCE(attrs->affn_scope == WQ_AFFN_NR_TYPES) &&
3830	likely(pt->nr_pods))
3831	return pt;
3832
3833	/*
3834	* Before workqueue_init_topology(), only SYSTEM is available which is
3835	* initialized in workqueue_init_early().
3836	*/
3837	pt = &wq_pod_types[WQ_AFFN_SYSTEM];
3838	BUG_ON(!pt->nr_pods);
3839	return pt;
3840	}
3841
3842	/**
3843	* init_worker_pool - initialize a newly zalloc'd worker_pool
3844	* @pool: worker_pool to initialize
3845	*
3846	* Initialize a newly zalloc'd @pool. It also allocates @pool->attrs.
3847	*
3848	* Return: 0 on success, -errno on failure. Even on failure, all fields
3849	* inside @pool proper are initialized and put_unbound_pool() can be called
3850	* on @pool safely to release it.
3851	*/
3852	static int init_worker_pool(struct worker_pool *pool)
3853	{
3854	raw_spin_lock_init(&pool->lock);
3855	pool->id = -1;
3856	pool->cpu = -1;
3857	pool->node = NUMA_NO_NODE;
3858	pool->flags \|= POOL_DISASSOCIATED;
3859	pool->watchdog_ts = jiffies;
3860	INIT_LIST_HEAD(&pool->worklist);
3861	INIT_LIST_HEAD(&pool->idle_list);
3862	hash_init(pool->busy_hash);
3863
3864	timer_setup(&pool->idle_timer, idle_worker_timeout, TIMER_DEFERRABLE);
3865	INIT_WORK(&pool->idle_cull_work, idle_cull_fn);
3866
3867	timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0);
3868
3869	INIT_LIST_HEAD(&pool->workers);
3870	INIT_LIST_HEAD(&pool->dying_workers);
3871
3872	ida_init(&pool->worker_ida);
3873	INIT_HLIST_NODE(&pool->hash_node);
3874	pool->refcnt = 1;
3875
3876	/* shouldn't fail above this point */
3877	pool->attrs = alloc_workqueue_attrs();
3878	if (!pool->attrs)
3879	return -ENOMEM;
3880
3881	wqattrs_clear_for_pool(pool->attrs);
3882
3883	return 0;
3884	}
3885
3886	#ifdef CONFIG_LOCKDEP
3887	static void wq_init_lockdep(struct workqueue_struct *wq)
3888	{
3889	char *lock_name;
3890
3891	lockdep_register_key(&wq->key);
3892	lock_name = kasprintf(GFP_KERNEL, "%s%s", "(wq_completion)", wq->name);
3893	if (!lock_name)
3894	lock_name = wq->name;
3895
3896	wq->lock_name = lock_name;
3897	lockdep_init_map(&wq->lockdep_map, lock_name, &wq->key, 0);
3898	}
3899
3900	static void wq_unregister_lockdep(struct workqueue_struct *wq)
3901	{
3902	lockdep_unregister_key(&wq->key);
3903	}
3904
3905	static void wq_free_lockdep(struct workqueue_struct *wq)
3906	{
3907	if (wq->lock_name != wq->name)
3908	kfree(wq->lock_name);
3909	}
3910	#else
3911	static void wq_init_lockdep(struct workqueue_struct *wq)
3912	{
3913	}
3914
3915	static void wq_unregister_lockdep(struct workqueue_struct *wq)
3916	{
3917	}
3918
3919	static void wq_free_lockdep(struct workqueue_struct *wq)
3920	{
3921	}
3922	#endif
3923
3924	static void rcu_free_wq(struct rcu_head *rcu)
3925	{
3926	struct workqueue_struct *wq =
3927	container_of(rcu, struct workqueue_struct, rcu);
3928
3929	wq_free_lockdep(wq);
3930	free_percpu(wq->cpu_pwq);
3931	free_workqueue_attrs(wq->unbound_attrs);
3932	kfree(wq);
3933	}
3934
3935	static void rcu_free_pool(struct rcu_head *rcu)
3936	{
3937	struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu);
3938
3939	ida_destroy(&pool->worker_ida);
3940	free_workqueue_attrs(pool->attrs);
3941	kfree(pool);
3942	}
3943
3944	/**
3945	* put_unbound_pool - put a worker_pool
3946	* @pool: worker_pool to put
3947	*
3948	* Put @pool. If its refcnt reaches zero, it gets destroyed in RCU
3949	* safe manner. get_unbound_pool() calls this function on its failure path
3950	* and this function should be able to release pools which went through,
3951	* successfully or not, init_worker_pool().
3952	*
3953	* Should be called with wq_pool_mutex held.
3954	*/
3955	static void put_unbound_pool(struct worker_pool *pool)
3956	{
3957	DECLARE_COMPLETION_ONSTACK(detach_completion);
3958	struct worker *worker;
3959	LIST_HEAD(cull_list);
3960
3961	lockdep_assert_held(&wq_pool_mutex);
3962
3963	if (--pool->refcnt)
3964	return;
3965
3966	/* sanity checks */
3967	if (WARN_ON(!(pool->cpu < 0)) \|\|
3968	WARN_ON(!list_empty(&pool->worklist)))
3969	return;
3970
3971	/* release id and unhash */
3972	if (pool->id >= 0)
3973	idr_remove(&worker_pool_idr, pool->id);
3974	hash_del(&pool->hash_node);
3975
3976	/*
3977	* Become the manager and destroy all workers. This prevents
3978	* @pool's workers from blocking on attach_mutex. We're the last
3979	* manager and @pool gets freed with the flag set.
3980	*
3981	* Having a concurrent manager is quite unlikely to happen as we can
3982	* only get here with
3983	* pwq->refcnt == pool->refcnt == 0
3984	* which implies no work queued to the pool, which implies no worker can
3985	* become the manager. However a worker could have taken the role of
3986	* manager before the refcnts dropped to 0, since maybe_create_worker()
3987	* drops pool->lock
3988	*/
3989	while (true) {
3990	rcuwait_wait_event(&manager_wait,
3991	!(pool->flags & POOL_MANAGER_ACTIVE),
3992	TASK_UNINTERRUPTIBLE);
3993
3994	mutex_lock(&wq_pool_attach_mutex);
3995	raw_spin_lock_irq(&pool->lock);
3996	if (!(pool->flags & POOL_MANAGER_ACTIVE)) {
3997	pool->flags \|= POOL_MANAGER_ACTIVE;
3998	break;
3999	}
4000	raw_spin_unlock_irq(&pool->lock);
4001	mutex_unlock(&wq_pool_attach_mutex);
4002	}
4003
4004	while ((worker = first_idle_worker(pool)))
4005	set_worker_dying(worker, &cull_list);
4006	WARN_ON(pool->nr_workers \|\| pool->nr_idle);
4007	raw_spin_unlock_irq(&pool->lock);
4008
4009	wake_dying_workers(&cull_list);
4010
4011	if (!list_empty(&pool->workers) \|\| !list_empty(&pool->dying_workers))
4012	pool->detach_completion = &detach_completion;
4013	mutex_unlock(&wq_pool_attach_mutex);
4014
4015	if (pool->detach_completion)
4016	wait_for_completion(pool->detach_completion);
4017
4018	/* shut down the timers */
4019	del_timer_sync(&pool->idle_timer);
4020	cancel_work_sync(&pool->idle_cull_work);
4021	del_timer_sync(&pool->mayday_timer);
4022
4023	/* RCU protected to allow dereferences from get_work_pool() */
4024	call_rcu(&pool->rcu, rcu_free_pool);
4025	}
4026
4027	/**
4028	* get_unbound_pool - get a worker_pool with the specified attributes
4029	* @attrs: the attributes of the worker_pool to get
4030	*
4031	* Obtain a worker_pool which has the same attributes as @attrs, bump the
4032	* reference count and return it. If there already is a matching
4033	* worker_pool, it will be used; otherwise, this function attempts to
4034	* create a new one.
4035	*
4036	* Should be called with wq_pool_mutex held.
4037	*
4038	* Return: On success, a worker_pool with the same attributes as @attrs.
4039	* On failure, %NULL.
4040	*/
4041	static struct worker_pool get_unbound_pool(const struct workqueue_attrs attrs)
4042	{
4043	struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_NUMA];
4044	u32 hash = wqattrs_hash(attrs);
4045	struct worker_pool *pool;
4046	int pod, node = NUMA_NO_NODE;
4047
4048	lockdep_assert_held(&wq_pool_mutex);
4049
4050	/* do we already have a matching pool? */
4051	hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) {
4052	if (wqattrs_equal(pool->attrs, attrs)) {
4053	pool->refcnt++;
4054	return pool;
4055	}
4056	}
4057
4058	/* If __pod_cpumask is contained inside a NUMA pod, that's our node */
4059	for (pod = 0; pod < pt->nr_pods; pod++) {
4060	if (cpumask_subset(attrs->__pod_cpumask, pt->pod_cpus[pod])) {
4061	node = pt->pod_node[pod];
4062	break;
4063	}
4064	}
4065
4066	/* nope, create a new one */
4067	pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, node);
4068	if (!pool \|\| init_worker_pool(pool) < 0)
4069	goto fail;
4070
4071	pool->node = node;
4072	copy_workqueue_attrs(pool->attrs, attrs);
4073	wqattrs_clear_for_pool(pool->attrs);
4074
4075	if (worker_pool_assign_id(pool) < 0)
4076	goto fail;
4077
4078	/* create and start the initial worker */
4079	if (wq_online && !create_worker(pool))
4080	goto fail;
4081
4082	/* install */
4083	hash_add(unbound_pool_hash, &pool->hash_node, hash);
4084
4085	return pool;
4086	fail:
4087	if (pool)
4088	put_unbound_pool(pool);
4089	return NULL;
4090	}
4091
4092	static void rcu_free_pwq(struct rcu_head *rcu)
4093	{
4094	kmem_cache_free(pwq_cache,
4095	container_of(rcu, struct pool_workqueue, rcu));
4096	}
4097
4098	/*
4099	* Scheduled on pwq_release_worker by put_pwq() when an unbound pwq hits zero
4100	* refcnt and needs to be destroyed.
4101	*/
4102	static void pwq_release_workfn(struct kthread_work *work)
4103	{
4104	struct pool_workqueue *pwq = container_of(work, struct pool_workqueue,
4105	release_work);
4106	struct workqueue_struct *wq = pwq->wq;
4107	struct worker_pool *pool = pwq->pool;
4108	bool is_last = false;
4109
4110	/*
4111	* When @pwq is not linked, it doesn't hold any reference to the
4112	* @wq, and @wq is invalid to access.
4113	*/
4114	if (!list_empty(&pwq->pwqs_node)) {
4115	mutex_lock(&wq->mutex);
4116	list_del_rcu(&pwq->pwqs_node);
4117	is_last = list_empty(&wq->pwqs);
4118	mutex_unlock(&wq->mutex);
4119	}
4120
4121	if (wq->flags & WQ_UNBOUND) {
4122	mutex_lock(&wq_pool_mutex);
4123	put_unbound_pool(pool);
4124	mutex_unlock(&wq_pool_mutex);
4125	}
4126
4127	call_rcu(&pwq->rcu, rcu_free_pwq);
4128
4129	/*
4130	* If we're the last pwq going away, @wq is already dead and no one
4131	* is gonna access it anymore. Schedule RCU free.
4132	*/
4133	if (is_last) {
4134	wq_unregister_lockdep(wq);
4135	call_rcu(&wq->rcu, rcu_free_wq);
4136	}
4137	}
4138
4139	/**
4140	* pwq_adjust_max_active - update a pwq's max_active to the current setting
4141	* @pwq: target pool_workqueue
4142	*
4143	* If @pwq isn't freezing, set @pwq->max_active to the associated
4144	* workqueue's saved_max_active and activate inactive work items
4145	* accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
4146	*/
4147	static void pwq_adjust_max_active(struct pool_workqueue *pwq)
4148	{
4149	struct workqueue_struct *wq = pwq->wq;
4150	bool freezable = wq->flags & WQ_FREEZABLE;
4151	unsigned long flags;
4152
4153	/* for @wq->saved_max_active */
4154	lockdep_assert_held(&wq->mutex);
4155
4156	/* fast exit for non-freezable wqs */
4157	if (!freezable && pwq->max_active == wq->saved_max_active)
4158	return;
4159
4160	/* this function can be called during early boot w/ irq disabled */
4161	raw_spin_lock_irqsave(&pwq->pool->lock, flags);
4162
4163	/*
4164	* During [un]freezing, the caller is responsible for ensuring that
4165	* this function is called at least once after @workqueue_freezing
4166	* is updated and visible.
4167	*/
4168	if (!freezable \|\| !workqueue_freezing) {
4169	pwq->max_active = wq->saved_max_active;
4170
4171	while (!list_empty(&pwq->inactive_works) &&
4172	pwq->nr_active < pwq->max_active)
4173	pwq_activate_first_inactive(pwq);
4174
4175	kick_pool(pwq->pool);
4176	} else {
4177	pwq->max_active = 0;
4178	}
4179
4180	raw_spin_unlock_irqrestore(&pwq->pool->lock, flags);
4181	}
4182
4183	/* initialize newly allocated @pwq which is associated with @wq and @pool */
4184	static void init_pwq(struct pool_workqueue pwq, struct workqueue_struct wq,
4185	struct worker_pool *pool)
4186	{
4187	BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);
4188
4189	memset(pwq, 0, sizeof(*pwq));
4190
4191	pwq->pool = pool;
4192	pwq->wq = wq;
4193	pwq->flush_color = -1;
4194	pwq->refcnt = 1;
4195	INIT_LIST_HEAD(&pwq->inactive_works);
4196	INIT_LIST_HEAD(&pwq->pwqs_node);
4197	INIT_LIST_HEAD(&pwq->mayday_node);
4198	kthread_init_work(&pwq->release_work, pwq_release_workfn);
4199	}
4200
4201	/* sync @pwq with the current state of its associated wq and link it */
4202	static void link_pwq(struct pool_workqueue *pwq)
4203	{
4204	struct workqueue_struct *wq = pwq->wq;
4205
4206	lockdep_assert_held(&wq->mutex);
4207
4208	/* may be called multiple times, ignore if already linked */
4209	if (!list_empty(&pwq->pwqs_node))
4210	return;
4211
4212	/* set the matching work_color */
4213	pwq->work_color = wq->work_color;
4214
4215	/* sync max_active to the current setting */
4216	pwq_adjust_max_active(pwq);
4217
4218	/* link in @pwq */
4219	list_add_rcu(&pwq->pwqs_node, &wq->pwqs);
4220	}
4221
4222	/* obtain a pool matching @attr and create a pwq associating the pool and @wq */
4223	static struct pool_workqueue alloc_unbound_pwq(struct workqueue_struct wq,
4224	const struct workqueue_attrs *attrs)
4225	{
4226	struct worker_pool *pool;
4227	struct pool_workqueue *pwq;
4228
4229	lockdep_assert_held(&wq_pool_mutex);
4230
4231	pool = get_unbound_pool(attrs);
4232	if (!pool)
4233	return NULL;
4234
4235	pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node);
4236	if (!pwq) {
4237	put_unbound_pool(pool);
4238	return NULL;
4239	}
4240
4241	init_pwq(pwq, wq, pool);
4242	return pwq;
4243	}
4244
4245	/**
4246	* wq_calc_pod_cpumask - calculate a wq_attrs' cpumask for a pod
4247	* @attrs: the wq_attrs of the default pwq of the target workqueue
4248	* @cpu: the target CPU
4249	* @cpu_going_down: if >= 0, the CPU to consider as offline
4250	*
4251	* Calculate the cpumask a workqueue with @attrs should use on @pod. If
4252	* @cpu_going_down is >= 0, that cpu is considered offline during calculation.
4253	* The result is stored in @attrs->__pod_cpumask.
4254	*
4255	* If pod affinity is not enabled, @attrs->cpumask is always used. If enabled
4256	* and @pod has online CPUs requested by @attrs, the returned cpumask is the
4257	* intersection of the possible CPUs of @pod and @attrs->cpumask.
4258	*
4259	* The caller is responsible for ensuring that the cpumask of @pod stays stable.
4260	*/
4261	static void wq_calc_pod_cpumask(struct workqueue_attrs *attrs, int cpu,
4262	int cpu_going_down)
4263	{
4264	const struct wq_pod_type *pt = wqattrs_pod_type(attrs);
4265	int pod = pt->cpu_pod[cpu];
4266
4267	/* does @pod have any online CPUs @attrs wants? */
4268	cpumask_and(attrs->__pod_cpumask, pt->pod_cpus[pod], attrs->cpumask);
4269	cpumask_and(attrs->__pod_cpumask, attrs->__pod_cpumask, cpu_online_mask);
4270	if (cpu_going_down >= 0)
4271	cpumask_clear_cpu(cpu_going_down, attrs->__pod_cpumask);
4272
4273	if (cpumask_empty(attrs->__pod_cpumask)) {
4274	cpumask_copy(attrs->__pod_cpumask, attrs->cpumask);
4275	return;
4276	}
4277
4278	/* yeap, return possible CPUs in @pod that @attrs wants */
4279	cpumask_and(attrs->__pod_cpumask, attrs->cpumask, pt->pod_cpus[pod]);
4280
4281	if (cpumask_empty(attrs->__pod_cpumask))
4282	pr_warn_once("WARNING: workqueue cpumask: online intersect > "
4283	"possible intersect\n");
4284	}
4285
4286	/* install @pwq into @wq's cpu_pwq and return the old pwq */
4287	static struct pool_workqueue install_unbound_pwq(struct workqueue_struct wq,
4288	int cpu, struct pool_workqueue *pwq)
4289	{
4290	struct pool_workqueue *old_pwq;
4291
4292	lockdep_assert_held(&wq_pool_mutex);
4293	lockdep_assert_held(&wq->mutex);
4294
4295	/* link_pwq() can handle duplicate calls */
4296	link_pwq(pwq);
4297
4298	old_pwq = rcu_access_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu));
4299	rcu_assign_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu), pwq);
4300	return old_pwq;
4301	}
4302
4303	/* context to store the prepared attrs & pwqs before applying */
4304	struct apply_wqattrs_ctx {
4305	struct workqueue_struct wq; / target workqueue */
4306	struct workqueue_attrs attrs; / attrs to apply */
4307	struct list_head list; /* queued for batching commit */
4308	struct pool_workqueue *dfl_pwq;
4309	struct pool_workqueue *pwq_tbl[];
4310	};
4311
4312	/* free the resources after success or abort */
4313	static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx)
4314	{
4315	if (ctx) {
4316	int cpu;
4317
4318	for_each_possible_cpu(cpu)
4319	put_pwq_unlocked(ctx->pwq_tbl[cpu]);
4320	put_pwq_unlocked(ctx->dfl_pwq);
4321
4322	free_workqueue_attrs(ctx->attrs);
4323
4324	kfree(ctx);
4325	}
4326	}
4327
4328	/* allocate the attrs and pwqs for later installation */
4329	static struct apply_wqattrs_ctx *
4330	apply_wqattrs_prepare(struct workqueue_struct *wq,
4331	const struct workqueue_attrs *attrs,
4332	const cpumask_var_t unbound_cpumask)
4333	{
4334	struct apply_wqattrs_ctx *ctx;
4335	struct workqueue_attrs *new_attrs;
4336	int cpu;
4337
4338	lockdep_assert_held(&wq_pool_mutex);
4339
4340	if (WARN_ON(attrs->affn_scope < 0 \|\|
4341	attrs->affn_scope >= WQ_AFFN_NR_TYPES))
4342	return ERR_PTR(-EINVAL);
4343
4344	ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_cpu_ids), GFP_KERNEL);
4345
4346	new_attrs = alloc_workqueue_attrs();
4347	if (!ctx \|\| !new_attrs)
4348	goto out_free;
4349
4350	/*
4351	* If something goes wrong during CPU up/down, we'll fall back to
4352	* the default pwq covering whole @attrs->cpumask. Always create
4353	* it even if we don't use it immediately.
4354	*/
4355	copy_workqueue_attrs(new_attrs, attrs);
4356	wqattrs_actualize_cpumask(new_attrs, unbound_cpumask);
4357	cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask);
4358	ctx->dfl_pwq = alloc_unbound_pwq(wq, new_attrs);
4359	if (!ctx->dfl_pwq)
4360	goto out_free;
4361
4362	for_each_possible_cpu(cpu) {
4363	if (new_attrs->ordered) {
4364	ctx->dfl_pwq->refcnt++;
4365	ctx->pwq_tbl[cpu] = ctx->dfl_pwq;
4366	} else {
4367	wq_calc_pod_cpumask(new_attrs, cpu, -1);
4368	ctx->pwq_tbl[cpu] = alloc_unbound_pwq(wq, new_attrs);
4369	if (!ctx->pwq_tbl[cpu])
4370	goto out_free;
4371	}
4372	}
4373
4374	/* save the user configured attrs and sanitize it. */
4375	copy_workqueue_attrs(new_attrs, attrs);
4376	cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);
4377	cpumask_copy(new_attrs->__pod_cpumask, new_attrs->cpumask);
4378	ctx->attrs = new_attrs;
4379
4380	ctx->wq = wq;
4381	return ctx;
4382
4383	out_free:
4384	free_workqueue_attrs(new_attrs);
4385	apply_wqattrs_cleanup(ctx);
4386	return ERR_PTR(-ENOMEM);
4387	}
4388
4389	/* set attrs and install prepared pwqs, @ctx points to old pwqs on return */
4390	static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx)
4391	{
4392	int cpu;
4393
4394	/* all pwqs have been created successfully, let's install'em */
4395	mutex_lock(&ctx->wq->mutex);
4396
4397	copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs);
4398
4399	/* save the previous pwq and install the new one */
4400	for_each_possible_cpu(cpu)
4401	ctx->pwq_tbl[cpu] = install_unbound_pwq(ctx->wq, cpu,
4402	ctx->pwq_tbl[cpu]);
4403
4404	/* @dfl_pwq might not have been used, ensure it's linked */
4405	link_pwq(ctx->dfl_pwq);
4406	swap(ctx->wq->dfl_pwq, ctx->dfl_pwq);
4407
4408	mutex_unlock(&ctx->wq->mutex);
4409	}
4410
4411	static void apply_wqattrs_lock(void)
4412	{
4413	/* CPUs should stay stable across pwq creations and installations */
4414	cpus_read_lock();
4415	mutex_lock(&wq_pool_mutex);
4416	}
4417
4418	static void apply_wqattrs_unlock(void)
4419	{
4420	mutex_unlock(&wq_pool_mutex);
4421	cpus_read_unlock();
4422	}
4423
4424	static int apply_workqueue_attrs_locked(struct workqueue_struct *wq,
4425	const struct workqueue_attrs *attrs)
4426	{
4427	struct apply_wqattrs_ctx *ctx;
4428
4429	/* only unbound workqueues can change attributes */
4430	if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
4431	return -EINVAL;
4432
4433	/* creating multiple pwqs breaks ordering guarantee */
4434	if (!list_empty(&wq->pwqs)) {
4435	if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT))
4436	return -EINVAL;
4437
4438	wq->flags &= ~__WQ_ORDERED;
4439	}
4440
4441	ctx = apply_wqattrs_prepare(wq, attrs, wq_unbound_cpumask);
4442	if (IS_ERR(ctx))
4443	return PTR_ERR(ctx);
4444
4445	/* the ctx has been prepared successfully, let's commit it */
4446	apply_wqattrs_commit(ctx);
4447	apply_wqattrs_cleanup(ctx);
4448
4449	return 0;
4450	}
4451
4452	/**
4453	* apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
4454	* @wq: the target workqueue
4455	* @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
4456	*
4457	* Apply @attrs to an unbound workqueue @wq. Unless disabled, this function maps
4458	* a separate pwq to each CPU pod with possibles CPUs in @attrs->cpumask so that
4459	* work items are affine to the pod it was issued on. Older pwqs are released as
4460	* in-flight work items finish. Note that a work item which repeatedly requeues
4461	* itself back-to-back will stay on its current pwq.
4462	*
4463	* Performs GFP_KERNEL allocations.
4464	*
4465	* Assumes caller has CPU hotplug read exclusion, i.e. cpus_read_lock().
4466	*
4467	* Return: 0 on success and -errno on failure.
4468	*/
4469	int apply_workqueue_attrs(struct workqueue_struct *wq,
4470	const struct workqueue_attrs *attrs)
4471	{
4472	int ret;
4473
4474	lockdep_assert_cpus_held();
4475
4476	mutex_lock(&wq_pool_mutex);
4477	ret = apply_workqueue_attrs_locked(wq, attrs);
4478	mutex_unlock(&wq_pool_mutex);
4479
4480	return ret;
4481	}
4482
4483	/**
4484	* wq_update_pod - update pod affinity of a wq for CPU hot[un]plug
4485	* @wq: the target workqueue
4486	* @cpu: the CPU to update pool association for
4487	* @hotplug_cpu: the CPU coming up or going down
4488	* @online: whether @cpu is coming up or going down
4489	*
4490	* This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
4491	* %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update pod affinity of
4492	* @wq accordingly.
4493	*
4494	*
4495	* If pod affinity can't be adjusted due to memory allocation failure, it falls
4496	* back to @wq->dfl_pwq which may not be optimal but is always correct.
4497	*
4498	* Note that when the last allowed CPU of a pod goes offline for a workqueue
4499	* with a cpumask spanning multiple pods, the workers which were already
4500	* executing the work items for the workqueue will lose their CPU affinity and
4501	* may execute on any CPU. This is similar to how per-cpu workqueues behave on
4502	* CPU_DOWN. If a workqueue user wants strict affinity, it's the user's
4503	* responsibility to flush the work item from CPU_DOWN_PREPARE.
4504	*/
4505	static void wq_update_pod(struct workqueue_struct *wq, int cpu,
4506	int hotplug_cpu, bool online)
4507	{
4508	int off_cpu = online ? -1 : hotplug_cpu;
4509	struct pool_workqueue old_pwq = NULL, pwq;
4510	struct workqueue_attrs *target_attrs;
4511
4512	lockdep_assert_held(&wq_pool_mutex);
4513
4514	if (!(wq->flags & WQ_UNBOUND) \|\| wq->unbound_attrs->ordered)
4515	return;
4516
4517	/*
4518	* We don't wanna alloc/free wq_attrs for each wq for each CPU.
4519	* Let's use a preallocated one. The following buf is protected by
4520	* CPU hotplug exclusion.
4521	*/
4522	target_attrs = wq_update_pod_attrs_buf;
4523
4524	copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
4525	wqattrs_actualize_cpumask(target_attrs, wq_unbound_cpumask);
4526
4527	/* nothing to do if the target cpumask matches the current pwq */
4528	wq_calc_pod_cpumask(target_attrs, cpu, off_cpu);
4529	pwq = rcu_dereference_protected(*per_cpu_ptr(wq->cpu_pwq, cpu),
4530	lockdep_is_held(&wq_pool_mutex));
4531	if (wqattrs_equal(target_attrs, pwq->pool->attrs))
4532	return;
4533
4534	/* create a new pwq */
4535	pwq = alloc_unbound_pwq(wq, target_attrs);
4536	if (!pwq) {
4537	pr_warn("workqueue: allocation failed while updating CPU pod affinity of \"%s\"\n",
4538	wq->name);
4539	goto use_dfl_pwq;
4540	}
4541
4542	/* Install the new pwq. */
4543	mutex_lock(&wq->mutex);
4544	old_pwq = install_unbound_pwq(wq, cpu, pwq);
4545	goto out_unlock;
4546
4547	use_dfl_pwq:
4548	mutex_lock(&wq->mutex);
4549	raw_spin_lock_irq(&wq->dfl_pwq->pool->lock);
4550	get_pwq(wq->dfl_pwq);
4551	raw_spin_unlock_irq(&wq->dfl_pwq->pool->lock);
4552	old_pwq = install_unbound_pwq(wq, cpu, wq->dfl_pwq);
4553	out_unlock:
4554	mutex_unlock(&wq->mutex);
4555	put_pwq_unlocked(old_pwq);
4556	}
4557
4558	static int alloc_and_link_pwqs(struct workqueue_struct *wq)
4559	{
4560	bool highpri = wq->flags & WQ_HIGHPRI;
4561	int cpu, ret;
4562
4563	wq->cpu_pwq = alloc_percpu(struct pool_workqueue *);
4564	if (!wq->cpu_pwq)
4565	goto enomem;
4566
4567	if (!(wq->flags & WQ_UNBOUND)) {
4568	for_each_possible_cpu(cpu) {
4569	struct pool_workqueue **pwq_p =
4570	per_cpu_ptr(wq->cpu_pwq, cpu);
4571	struct worker_pool *pool =
4572	&(per_cpu_ptr(cpu_worker_pools, cpu)[highpri]);
4573
4574	*pwq_p = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL,
4575	pool->node);
4576	if (!*pwq_p)
4577	goto enomem;
4578
4579	init_pwq(*pwq_p, wq, pool);
4580
4581	mutex_lock(&wq->mutex);
4582	link_pwq(*pwq_p);
4583	mutex_unlock(&wq->mutex);
4584	}
4585	return 0;
4586	}
4587
4588	cpus_read_lock();
4589	if (wq->flags & __WQ_ORDERED) {
4590	ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]);
4591	/* there should only be single pwq for ordering guarantee */
4592	WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node \|\|
4593	wq->pwqs.prev != &wq->dfl_pwq->pwqs_node),
4594	"ordering guarantee broken for workqueue %s\n", wq->name);
4595	} else {
4596	ret = apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
4597	}
4598	cpus_read_unlock();
4599
4600	/* for unbound pwq, flush the pwq_release_worker ensures that the
4601	* pwq_release_workfn() completes before calling kfree(wq).
4602	*/
4603	if (ret)
4604	kthread_flush_worker(pwq_release_worker);
4605
4606	return ret;
4607
4608	enomem:
4609	if (wq->cpu_pwq) {
4610	for_each_possible_cpu(cpu) {
4611	struct pool_workqueue pwq = per_cpu_ptr(wq->cpu_pwq, cpu);
4612
4613	if (pwq)
4614	kmem_cache_free(pwq_cache, pwq);
4615	}
4616	free_percpu(wq->cpu_pwq);
4617	wq->cpu_pwq = NULL;
4618	}
4619	return -ENOMEM;
4620	}
4621
4622	static int wq_clamp_max_active(int max_active, unsigned int flags,
4623	const char *name)
4624	{
4625	if (max_active < 1 \|\| max_active > WQ_MAX_ACTIVE)
4626	pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
4627	max_active, name, 1, WQ_MAX_ACTIVE);
4628
4629	return clamp_val(max_active, 1, WQ_MAX_ACTIVE);
4630	}
4631
4632	/*
4633	* Workqueues which may be used during memory reclaim should have a rescuer
4634	* to guarantee forward progress.
4635	*/
4636	static int init_rescuer(struct workqueue_struct *wq)
4637	{
4638	struct worker *rescuer;
4639	int ret;
4640
4641	if (!(wq->flags & WQ_MEM_RECLAIM))
4642	return 0;
4643
4644	rescuer = alloc_worker(NUMA_NO_NODE);
4645	if (!rescuer) {
4646	pr_err("workqueue: Failed to allocate a rescuer for wq \"%s\"\n",
4647	wq->name);
4648	return -ENOMEM;
4649	}
4650
4651	rescuer->rescue_wq = wq;
4652	rescuer->task = kthread_create(rescuer_thread, rescuer, "kworker/R-%s", wq->name);
4653	if (IS_ERR(rescuer->task)) {
4654	ret = PTR_ERR(rescuer->task);
4655	pr_err("workqueue: Failed to create a rescuer kthread for wq \"%s\": %pe",
4656	wq->name, ERR_PTR(ret));
4657	kfree(rescuer);
4658	return ret;
4659	}
4660
4661	wq->rescuer = rescuer;
4662	kthread_bind_mask(rescuer->task, cpu_possible_mask);
4663	wake_up_process(rescuer->task);
4664
4665	return 0;
4666	}
4667
4668	__printf(1, 4)
4669	struct workqueue_struct alloc_workqueue(const char fmt,
4670	unsigned int flags,
4671	int max_active, ...)
4672	{
4673	va_list args;
4674	struct workqueue_struct *wq;
4675	struct pool_workqueue *pwq;
4676
4677	/*
4678	* Unbound && max_active == 1 used to imply ordered, which is no longer
4679	* the case on many machines due to per-pod pools. While
4680	* alloc_ordered_workqueue() is the right way to create an ordered
4681	* workqueue, keep the previous behavior to avoid subtle breakages.
4682	*/
4683	if ((flags & WQ_UNBOUND) && max_active == 1)
4684	flags \|= __WQ_ORDERED;
4685
4686	/* see the comment above the definition of WQ_POWER_EFFICIENT */
4687	if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
4688	flags \|= WQ_UNBOUND;
4689
4690	/* allocate wq and format name */
4691	wq = kzalloc(sizeof(*wq), GFP_KERNEL);
4692	if (!wq)
4693	return NULL;
4694
4695	if (flags & WQ_UNBOUND) {
4696	wq->unbound_attrs = alloc_workqueue_attrs();
4697	if (!wq->unbound_attrs)
4698	goto err_free_wq;
4699	}
4700
4701	va_start(args, max_active);
4702	vsnprintf(wq->name, sizeof(wq->name), fmt, args);
4703	va_end(args);
4704
4705	max_active = max_active ?: WQ_DFL_ACTIVE;
4706	max_active = wq_clamp_max_active(max_active, flags, wq->name);
4707
4708	/* init wq */
4709	wq->flags = flags;
4710	wq->saved_max_active = max_active;
4711	mutex_init(&wq->mutex);
4712	atomic_set(&wq->nr_pwqs_to_flush, 0);
4713	INIT_LIST_HEAD(&wq->pwqs);
4714	INIT_LIST_HEAD(&wq->flusher_queue);
4715	INIT_LIST_HEAD(&wq->flusher_overflow);
4716	INIT_LIST_HEAD(&wq->maydays);
4717
4718	wq_init_lockdep(wq);
4719	INIT_LIST_HEAD(&wq->list);
4720
4721	if (alloc_and_link_pwqs(wq) < 0)
4722	goto err_unreg_lockdep;
4723
4724	if (wq_online && init_rescuer(wq) < 0)
4725	goto err_destroy;
4726
4727	if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq))
4728	goto err_destroy;
4729
4730	/*
4731	* wq_pool_mutex protects global freeze state and workqueues list.
4732	* Grab it, adjust max_active and add the new @wq to workqueues
4733	* list.
4734	*/
4735	mutex_lock(&wq_pool_mutex);
4736
4737	mutex_lock(&wq->mutex);
4738	for_each_pwq(pwq, wq)
4739	pwq_adjust_max_active(pwq);
4740	mutex_unlock(&wq->mutex);
4741
4742	list_add_tail_rcu(&wq->list, &workqueues);
4743
4744	mutex_unlock(&wq_pool_mutex);
4745
4746	return wq;
4747
4748	err_unreg_lockdep:
4749	wq_unregister_lockdep(wq);
4750	wq_free_lockdep(wq);
4751	err_free_wq:
4752	free_workqueue_attrs(wq->unbound_attrs);
4753	kfree(wq);
4754	return NULL;
4755	err_destroy:
4756	destroy_workqueue(wq);
4757	return NULL;
4758	}
4759	EXPORT_SYMBOL_GPL(alloc_workqueue);
4760
4761	static bool pwq_busy(struct pool_workqueue *pwq)
4762	{
4763	int i;
4764
4765	for (i = 0; i < WORK_NR_COLORS; i++)
4766	if (pwq->nr_in_flight[i])
4767	return true;
4768
4769	if ((pwq != pwq->wq->dfl_pwq) && (pwq->refcnt > 1))
4770	return true;
4771	if (pwq->nr_active \|\| !list_empty(&pwq->inactive_works))
4772	return true;
4773
4774	return false;
4775	}
4776
4777	/**
4778	* destroy_workqueue - safely terminate a workqueue
4779	* @wq: target workqueue
4780	*
4781	* Safely destroy a workqueue. All work currently pending will be done first.
4782	*/
4783	void destroy_workqueue(struct workqueue_struct *wq)
4784	{
4785	struct pool_workqueue *pwq;
4786	int cpu;
4787
4788	/*
4789	* Remove it from sysfs first so that sanity check failure doesn't
4790	* lead to sysfs name conflicts.
4791	*/
4792	workqueue_sysfs_unregister(wq);
4793
4794	/* mark the workqueue destruction is in progress */
4795	mutex_lock(&wq->mutex);
4796	wq->flags \|= __WQ_DESTROYING;
4797	mutex_unlock(&wq->mutex);
4798
4799	/* drain it before proceeding with destruction */
4800	drain_workqueue(wq);
4801
4802	/* kill rescuer, if sanity checks fail, leave it w/o rescuer */
4803	if (wq->rescuer) {
4804	struct worker *rescuer = wq->rescuer;
4805
4806	/* this prevents new queueing */
4807	raw_spin_lock_irq(&wq_mayday_lock);
4808	wq->rescuer = NULL;
4809	raw_spin_unlock_irq(&wq_mayday_lock);
4810
4811	/* rescuer will empty maydays list before exiting */
4812	kthread_stop(rescuer->task);
4813	kfree(rescuer);
4814	}
4815
4816	/*
4817	* Sanity checks - grab all the locks so that we wait for all
4818	* in-flight operations which may do put_pwq().
4819	*/
4820	mutex_lock(&wq_pool_mutex);
4821	mutex_lock(&wq->mutex);
4822	for_each_pwq(pwq, wq) {
4823	raw_spin_lock_irq(&pwq->pool->lock);
4824	if (WARN_ON(pwq_busy(pwq))) {
4825	pr_warn("%s: %s has the following busy pwq\n",
4826	__func__, wq->name);
4827	show_pwq(pwq);
4828	raw_spin_unlock_irq(&pwq->pool->lock);
4829	mutex_unlock(&wq->mutex);
4830	mutex_unlock(&wq_pool_mutex);
4831	show_one_workqueue(wq);
4832	return;
4833	}
4834	raw_spin_unlock_irq(&pwq->pool->lock);
4835	}
4836	mutex_unlock(&wq->mutex);
4837
4838	/*
4839	* wq list is used to freeze wq, remove from list after
4840	* flushing is complete in case freeze races us.
4841	*/
4842	list_del_rcu(&wq->list);
4843	mutex_unlock(&wq_pool_mutex);
4844
4845	/*
4846	* We're the sole accessor of @wq. Directly access cpu_pwq and dfl_pwq
4847	* to put the base refs. @wq will be auto-destroyed from the last
4848	* pwq_put. RCU read lock prevents @wq from going away from under us.
4849	*/
4850	rcu_read_lock();
4851
4852	for_each_possible_cpu(cpu) {
4853	pwq = rcu_access_pointer(*per_cpu_ptr(wq->cpu_pwq, cpu));
4854	RCU_INIT_POINTER(*per_cpu_ptr(wq->cpu_pwq, cpu), NULL);
4855	put_pwq_unlocked(pwq);
4856	}
4857
4858	put_pwq_unlocked(wq->dfl_pwq);
4859	wq->dfl_pwq = NULL;
4860
4861	rcu_read_unlock();
4862	}
4863	EXPORT_SYMBOL_GPL(destroy_workqueue);
4864
4865	/**
4866	* workqueue_set_max_active - adjust max_active of a workqueue
4867	* @wq: target workqueue
4868	* @max_active: new max_active value.
4869	*
4870	* Set max_active of @wq to @max_active.
4871	*
4872	* CONTEXT:
4873	* Don't call from IRQ context.
4874	*/
4875	void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
4876	{
4877	struct pool_workqueue *pwq;
4878
4879	/* disallow meddling with max_active for ordered workqueues */
4880	if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT))
4881	return;
4882
4883	max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
4884
4885	mutex_lock(&wq->mutex);
4886
4887	wq->flags &= ~__WQ_ORDERED;
4888	wq->saved_max_active = max_active;
4889
4890	for_each_pwq(pwq, wq)
4891	pwq_adjust_max_active(pwq);
4892
4893	mutex_unlock(&wq->mutex);
4894	}
4895	EXPORT_SYMBOL_GPL(workqueue_set_max_active);
4896
4897	/**
4898	* current_work - retrieve %current task's work struct
4899	*
4900	* Determine if %current task is a workqueue worker and what it's working on.
4901	* Useful to find out the context that the %current task is running in.
4902	*
4903	* Return: work struct if %current task is a workqueue worker, %NULL otherwise.
4904	*/
4905	struct work_struct *current_work(void)
4906	{
4907	struct worker *worker = current_wq_worker();
4908
4909	return worker ? worker->current_work : NULL;
4910	}
4911	EXPORT_SYMBOL(current_work);
4912
4913	/**
4914	* current_is_workqueue_rescuer - is %current workqueue rescuer?
4915	*
4916	* Determine whether %current is a workqueue rescuer. Can be used from
4917	* work functions to determine whether it's being run off the rescuer task.
4918	*
4919	* Return: %true if %current is a workqueue rescuer. %false otherwise.
4920	*/
4921	bool current_is_workqueue_rescuer(void)
4922	{
4923	struct worker *worker = current_wq_worker();
4924
4925	return worker && worker->rescue_wq;
4926	}
4927
4928	/**
4929	* workqueue_congested - test whether a workqueue is congested
4930	* @cpu: CPU in question
4931	* @wq: target workqueue
4932	*
4933	* Test whether @wq's cpu workqueue for @cpu is congested. There is
4934	* no synchronization around this function and the test result is
4935	* unreliable and only useful as advisory hints or for debugging.
4936	*
4937	* If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU.
4938	*
4939	* With the exception of ordered workqueues, all workqueues have per-cpu
4940	* pool_workqueues, each with its own congested state. A workqueue being
4941	* congested on one CPU doesn't mean that the workqueue is contested on any
4942	* other CPUs.
4943	*
4944	* Return:
4945	* %true if congested, %false otherwise.
4946	*/
4947	bool workqueue_congested(int cpu, struct workqueue_struct *wq)
4948	{
4949	struct pool_workqueue *pwq;
4950	bool ret;
4951
4952	rcu_read_lock();
4953	preempt_disable();
4954
4955	if (cpu == WORK_CPU_UNBOUND)
4956	cpu = smp_processor_id();
4957
4958	pwq = *per_cpu_ptr(wq->cpu_pwq, cpu);
4959	ret = !list_empty(&pwq->inactive_works);
4960
4961	preempt_enable();
4962	rcu_read_unlock();
4963
4964	return ret;
4965	}
4966	EXPORT_SYMBOL_GPL(workqueue_congested);
4967
4968	/**
4969	* work_busy - test whether a work is currently pending or running
4970	* @work: the work to be tested
4971	*
4972	* Test whether @work is currently pending or running. There is no
4973	* synchronization around this function and the test result is
4974	* unreliable and only useful as advisory hints or for debugging.
4975	*
4976	* Return:
4977	* OR'd bitmask of WORK_BUSY_* bits.
4978	*/
4979	unsigned int work_busy(struct work_struct *work)
4980	{
4981	struct worker_pool *pool;
4982	unsigned long flags;
4983	unsigned int ret = 0;
4984
4985	if (work_pending(work))
4986	ret \|= WORK_BUSY_PENDING;
4987
4988	rcu_read_lock();
4989	pool = get_work_pool(work);
4990	if (pool) {
4991	raw_spin_lock_irqsave(&pool->lock, flags);
4992	if (find_worker_executing_work(pool, work))
4993	ret \|= WORK_BUSY_RUNNING;
4994	raw_spin_unlock_irqrestore(&pool->lock, flags);
4995	}
4996	rcu_read_unlock();
4997
4998	return ret;
4999	}
5000	EXPORT_SYMBOL_GPL(work_busy);
5001
5002	/**
5003	* set_worker_desc - set description for the current work item
5004	* @fmt: printf-style format string
5005	* @...: arguments for the format string
5006	*
5007	* This function can be called by a running work function to describe what
5008	* the work item is about. If the worker task gets dumped, this
5009	* information will be printed out together to help debugging. The
5010	* description can be at most WORKER_DESC_LEN including the trailing '\0'.
5011	*/
5012	void set_worker_desc(const char *fmt, ...)
5013	{
5014	struct worker *worker = current_wq_worker();
5015	va_list args;
5016
5017	if (worker) {
5018	va_start(args, fmt);
5019	vsnprintf(worker->desc, sizeof(worker->desc), fmt, args);
5020	va_end(args);
5021	}
5022	}
5023	EXPORT_SYMBOL_GPL(set_worker_desc);
5024
5025	/**
5026	* print_worker_info - print out worker information and description
5027	* @log_lvl: the log level to use when printing
5028	* @task: target task
5029	*
5030	* If @task is a worker and currently executing a work item, print out the
5031	* name of the workqueue being serviced and worker description set with
5032	* set_worker_desc() by the currently executing work item.
5033	*
5034	* This function can be safely called on any task as long as the
5035	* task_struct itself is accessible. While safe, this function isn't
5036	* synchronized and may print out mixups or garbages of limited length.
5037	*/
5038	void print_worker_info(const char log_lvl, struct task_struct task)
5039	{
5040	work_func_t *fn = NULL;
5041	char name[WQ_NAME_LEN] = { };
5042	char desc[WORKER_DESC_LEN] = { };
5043	struct pool_workqueue *pwq = NULL;
5044	struct workqueue_struct *wq = NULL;
5045	struct worker *worker;
5046
5047	if (!(task->flags & PF_WQ_WORKER))
5048	return;
5049
5050	/*
5051	* This function is called without any synchronization and @task
5052	* could be in any state. Be careful with dereferences.
5053	*/
5054	worker = kthread_probe_data(task);
5055
5056	/*
5057	* Carefully copy the associated workqueue's workfn, name and desc.
5058	* Keep the original last '\0' in case the original is garbage.
5059	*/
5060	copy_from_kernel_nofault(&fn, &worker->current_func, sizeof(fn));
5061	copy_from_kernel_nofault(&pwq, &worker->current_pwq, sizeof(pwq));
5062	copy_from_kernel_nofault(&wq, &pwq->wq, sizeof(wq));
5063	copy_from_kernel_nofault(name, wq->name, sizeof(name) - 1);
5064	copy_from_kernel_nofault(desc, worker->desc, sizeof(desc) - 1);
5065
5066	if (fn \|\| name[0] \|\| desc[0]) {
5067	printk("%sWorkqueue: %s %ps", log_lvl, name, fn);
5068	if (strcmp(name, desc))
5069	pr_cont(" (%s)", desc);
5070	pr_cont("\n");
5071	}
5072	}
5073
5074	static void pr_cont_pool_info(struct worker_pool *pool)
5075	{
5076	pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask);
5077	if (pool->node != NUMA_NO_NODE)
5078	pr_cont(" node=%d", pool->node);
5079	pr_cont(" flags=0x%x nice=%d", pool->flags, pool->attrs->nice);
5080	}
5081
5082	struct pr_cont_work_struct {
5083	bool comma;
5084	work_func_t func;
5085	long ctr;
5086	};
5087
5088	static void pr_cont_work_flush(bool comma, work_func_t func, struct pr_cont_work_struct *pcwsp)
5089	{
5090	if (!pcwsp->ctr)
5091	goto out_record;
5092	if (func == pcwsp->func) {
5093	pcwsp->ctr++;
5094	return;
5095	}
5096	if (pcwsp->ctr == 1)
5097	pr_cont("%s %ps", pcwsp->comma ? "," : "", pcwsp->func);
5098	else
5099	pr_cont("%s %ld*%ps", pcwsp->comma ? "," : "", pcwsp->ctr, pcwsp->func);
5100	pcwsp->ctr = 0;
5101	out_record:
5102	if ((long)func == -1L)
5103	return;
5104	pcwsp->comma = comma;
5105	pcwsp->func = func;
5106	pcwsp->ctr = 1;
5107	}
5108
5109	static void pr_cont_work(bool comma, struct work_struct work, struct pr_cont_work_struct pcwsp)
5110	{
5111	if (work->func == wq_barrier_func) {
5112	struct wq_barrier *barr;
5113
5114	barr = container_of(work, struct wq_barrier, work);
5115
5116	pr_cont_work_flush(comma, (work_func_t)-1, pcwsp);
5117	pr_cont("%s BAR(%d)", comma ? "," : "",
5118	task_pid_nr(barr->task));
5119	} else {
5120	if (!comma)
5121	pr_cont_work_flush(comma, (work_func_t)-1, pcwsp);
5122	pr_cont_work_flush(comma, work->func, pcwsp);
5123	}
5124	}
5125
5126	static void show_pwq(struct pool_workqueue *pwq)
5127	{
5128	struct pr_cont_work_struct pcws = { .ctr = 0, };
5129	struct worker_pool *pool = pwq->pool;
5130	struct work_struct *work;
5131	struct worker *worker;
5132	bool has_in_flight = false, has_pending = false;
5133	int bkt;
5134
5135	pr_info(" pwq %d:", pool->id);
5136	pr_cont_pool_info(pool);
5137
5138	pr_cont(" active=%d/%d refcnt=%d%s\n",
5139	pwq->nr_active, pwq->max_active, pwq->refcnt,
5140	!list_empty(&pwq->mayday_node) ? " MAYDAY" : "");
5141
5142	hash_for_each(pool->busy_hash, bkt, worker, hentry) {
5143	if (worker->current_pwq == pwq) {
5144	has_in_flight = true;
5145	break;
5146	}
5147	}
5148	if (has_in_flight) {
5149	bool comma = false;
5150
5151	pr_info(" in-flight:");
5152	hash_for_each(pool->busy_hash, bkt, worker, hentry) {
5153	if (worker->current_pwq != pwq)
5154	continue;
5155
5156	pr_cont("%s %d%s:%ps", comma ? "," : "",
5157	task_pid_nr(worker->task),
5158	worker->rescue_wq ? "(RESCUER)" : "",
5159	worker->current_func);
5160	list_for_each_entry(work, &worker->scheduled, entry)
5161	pr_cont_work(false, work, &pcws);
5162	pr_cont_work_flush(comma, (work_func_t)-1L, &pcws);
5163	comma = true;
5164	}
5165	pr_cont("\n");
5166	}
5167
5168	list_for_each_entry(work, &pool->worklist, entry) {
5169	if (get_work_pwq(work) == pwq) {
5170	has_pending = true;
5171	break;
5172	}
5173	}
5174	if (has_pending) {
5175	bool comma = false;
5176
5177	pr_info(" pending:");
5178	list_for_each_entry(work, &pool->worklist, entry) {
5179	if (get_work_pwq(work) != pwq)
5180	continue;
5181
5182	pr_cont_work(comma, work, &pcws);
5183	comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED);
5184	}
5185	pr_cont_work_flush(comma, (work_func_t)-1L, &pcws);
5186	pr_cont("\n");
5187	}
5188
5189	if (!list_empty(&pwq->inactive_works)) {
5190	bool comma = false;
5191
5192	pr_info(" inactive:");
5193	list_for_each_entry(work, &pwq->inactive_works, entry) {
5194	pr_cont_work(comma, work, &pcws);
5195	comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED);
5196	}
5197	pr_cont_work_flush(comma, (work_func_t)-1L, &pcws);
5198	pr_cont("\n");
5199	}
5200	}
5201
5202	/**
5203	* show_one_workqueue - dump state of specified workqueue
5204	* @wq: workqueue whose state will be printed
5205	*/
5206	void show_one_workqueue(struct workqueue_struct *wq)
5207	{
5208	struct pool_workqueue *pwq;
5209	bool idle = true;
5210	unsigned long flags;
5211
5212	for_each_pwq(pwq, wq) {
5213	if (pwq->nr_active \|\| !list_empty(&pwq->inactive_works)) {
5214	idle = false;
5215	break;
5216	}
5217	}
5218	if (idle) /* Nothing to print for idle workqueue */
5219	return;
5220
5221	pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags);
5222
5223	for_each_pwq(pwq, wq) {
5224	raw_spin_lock_irqsave(&pwq->pool->lock, flags);
5225	if (pwq->nr_active \|\| !list_empty(&pwq->inactive_works)) {
5226	/*
5227	* Defer printing to avoid deadlocks in console
5228	* drivers that queue work while holding locks
5229	* also taken in their write paths.
5230	*/
5231	printk_deferred_enter();
5232	show_pwq(pwq);
5233	printk_deferred_exit();
5234	}
5235	raw_spin_unlock_irqrestore(&pwq->pool->lock, flags);
5236	/*
5237	* We could be printing a lot from atomic context, e.g.
5238	* sysrq-t -> show_all_workqueues(). Avoid triggering
5239	* hard lockup.
5240	*/
5241	touch_nmi_watchdog();
5242	}
5243
5244	}
5245
5246	/**
5247	* show_one_worker_pool - dump state of specified worker pool
5248	* @pool: worker pool whose state will be printed
5249	*/
5250	static void show_one_worker_pool(struct worker_pool *pool)
5251	{
5252	struct worker *worker;
5253	bool first = true;
5254	unsigned long flags;
5255	unsigned long hung = 0;
5256
5257	raw_spin_lock_irqsave(&pool->lock, flags);
5258	if (pool->nr_workers == pool->nr_idle)
5259	goto next_pool;
5260
5261	/* How long the first pending work is waiting for a worker. */
5262	if (!list_empty(&pool->worklist))
5263	hung = jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000;
5264
5265	/*
5266	* Defer printing to avoid deadlocks in console drivers that
5267	* queue work while holding locks also taken in their write
5268	* paths.
5269	*/
5270	printk_deferred_enter();
5271	pr_info("pool %d:", pool->id);
5272	pr_cont_pool_info(pool);
5273	pr_cont(" hung=%lus workers=%d", hung, pool->nr_workers);
5274	if (pool->manager)
5275	pr_cont(" manager: %d",
5276	task_pid_nr(pool->manager->task));
5277	list_for_each_entry(worker, &pool->idle_list, entry) {
5278	pr_cont(" %s%d", first ? "idle: " : "",
5279	task_pid_nr(worker->task));
5280	first = false;
5281	}
5282	pr_cont("\n");
5283	printk_deferred_exit();
5284	next_pool:
5285	raw_spin_unlock_irqrestore(&pool->lock, flags);
5286	/*
5287	* We could be printing a lot from atomic context, e.g.
5288	* sysrq-t -> show_all_workqueues(). Avoid triggering
5289	* hard lockup.
5290	*/
5291	touch_nmi_watchdog();
5292
5293	}
5294
5295	/**
5296	* show_all_workqueues - dump workqueue state
5297	*
5298	* Called from a sysrq handler and prints out all busy workqueues and pools.
5299	*/
5300	void show_all_workqueues(void)
5301	{
5302	struct workqueue_struct *wq;
5303	struct worker_pool *pool;
5304	int pi;
5305
5306	rcu_read_lock();
5307
5308	pr_info("Showing busy workqueues and worker pools:\n");
5309
5310	list_for_each_entry_rcu(wq, &workqueues, list)
5311	show_one_workqueue(wq);
5312
5313	for_each_pool(pool, pi)
5314	show_one_worker_pool(pool);
5315
5316	rcu_read_unlock();
5317	}
5318
5319	/**
5320	* show_freezable_workqueues - dump freezable workqueue state
5321	*
5322	* Called from try_to_freeze_tasks() and prints out all freezable workqueues
5323	* still busy.
5324	*/
5325	void show_freezable_workqueues(void)
5326	{
5327	struct workqueue_struct *wq;
5328
5329	rcu_read_lock();
5330
5331	pr_info("Showing freezable workqueues that are still busy:\n");
5332
5333	list_for_each_entry_rcu(wq, &workqueues, list) {
5334	if (!(wq->flags & WQ_FREEZABLE))
5335	continue;
5336	show_one_workqueue(wq);
5337	}
5338
5339	rcu_read_unlock();
5340	}
5341
5342	/* used to show worker information through /proc/PID/{comm,stat,status} */
5343	void wq_worker_comm(char buf, size_t size, struct task_struct task)
5344	{
5345	int off;
5346
5347	/* always show the actual comm */
5348	off = strscpy(buf, task->comm, size);
5349	if (off < 0)
5350	return;
5351
5352	/* stabilize PF_WQ_WORKER and worker pool association */
5353	mutex_lock(&wq_pool_attach_mutex);
5354
5355	if (task->flags & PF_WQ_WORKER) {
5356	struct worker *worker = kthread_data(task);
5357	struct worker_pool *pool = worker->pool;
5358
5359	if (pool) {
5360	raw_spin_lock_irq(&pool->lock);
5361	/*
5362	* ->desc tracks information (wq name or
5363	* set_worker_desc()) for the latest execution. If
5364	* current, prepend '+', otherwise '-'.
5365	*/
5366	if (worker->desc[0] != '\0') {
5367	if (worker->current_work)
5368	scnprintf(buf + off, size - off, "+%s",
5369	worker->desc);
5370	else
5371	scnprintf(buf + off, size - off, "-%s",
5372	worker->desc);
5373	}
5374	raw_spin_unlock_irq(&pool->lock);
5375	}
5376	}
5377
5378	mutex_unlock(&wq_pool_attach_mutex);
5379	}
5380
5381	#ifdef CONFIG_SMP
5382
5383	/*
5384	* CPU hotplug.
5385	*
5386	* There are two challenges in supporting CPU hotplug. Firstly, there
5387	* are a lot of assumptions on strong associations among work, pwq and
5388	* pool which make migrating pending and scheduled works very
5389	* difficult to implement without impacting hot paths. Secondly,
5390	* worker pools serve mix of short, long and very long running works making
5391	* blocked draining impractical.
5392	*
5393	* This is solved by allowing the pools to be disassociated from the CPU
5394	* running as an unbound one and allowing it to be reattached later if the
5395	* cpu comes back online.
5396	*/
5397
5398	static void unbind_workers(int cpu)
5399	{
5400	struct worker_pool *pool;
5401	struct worker *worker;
5402
5403	for_each_cpu_worker_pool(pool, cpu) {
5404	mutex_lock(&wq_pool_attach_mutex);
5405	raw_spin_lock_irq(&pool->lock);
5406
5407	/*
5408	* We've blocked all attach/detach operations. Make all workers
5409	* unbound and set DISASSOCIATED. Before this, all workers
5410	* must be on the cpu. After this, they may become diasporas.
5411	* And the preemption disabled section in their sched callbacks
5412	* are guaranteed to see WORKER_UNBOUND since the code here
5413	* is on the same cpu.
5414	*/
5415	for_each_pool_worker(worker, pool)
5416	worker->flags \|= WORKER_UNBOUND;
5417
5418	pool->flags \|= POOL_DISASSOCIATED;
5419
5420	/*
5421	* The handling of nr_running in sched callbacks are disabled
5422	* now. Zap nr_running. After this, nr_running stays zero and
5423	* need_more_worker() and keep_working() are always true as
5424	* long as the worklist is not empty. This pool now behaves as
5425	* an unbound (in terms of concurrency management) pool which
5426	* are served by workers tied to the pool.
5427	*/
5428	pool->nr_running = 0;
5429
5430	/*
5431	* With concurrency management just turned off, a busy
5432	* worker blocking could lead to lengthy stalls. Kick off
5433	* unbound chain execution of currently pending work items.
5434	*/
5435	kick_pool(pool);
5436
5437	raw_spin_unlock_irq(&pool->lock);
5438
5439	for_each_pool_worker(worker, pool)
5440	unbind_worker(worker);
5441
5442	mutex_unlock(&wq_pool_attach_mutex);
5443	}
5444	}
5445
5446	/**
5447	* rebind_workers - rebind all workers of a pool to the associated CPU
5448	* @pool: pool of interest
5449	*
5450	* @pool->cpu is coming online. Rebind all workers to the CPU.
5451	*/
5452	static void rebind_workers(struct worker_pool *pool)
5453	{
5454	struct worker *worker;
5455
5456	lockdep_assert_held(&wq_pool_attach_mutex);
5457
5458	/*
5459	* Restore CPU affinity of all workers. As all idle workers should
5460	* be on the run-queue of the associated CPU before any local
5461	* wake-ups for concurrency management happen, restore CPU affinity
5462	* of all workers first and then clear UNBOUND. As we're called
5463	* from CPU_ONLINE, the following shouldn't fail.
5464	*/
5465	for_each_pool_worker(worker, pool) {
5466	kthread_set_per_cpu(worker->task, pool->cpu);
5467	WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
5468	pool_allowed_cpus(pool)) < 0);
5469	}
5470
5471	raw_spin_lock_irq(&pool->lock);
5472
5473	pool->flags &= ~POOL_DISASSOCIATED;
5474
5475	for_each_pool_worker(worker, pool) {
5476	unsigned int worker_flags = worker->flags;
5477
5478	/*
5479	* We want to clear UNBOUND but can't directly call
5480	* worker_clr_flags() or adjust nr_running. Atomically
5481	* replace UNBOUND with another NOT_RUNNING flag REBOUND.
5482	* @worker will clear REBOUND using worker_clr_flags() when
5483	* it initiates the next execution cycle thus restoring
5484	* concurrency management. Note that when or whether
5485	* @worker clears REBOUND doesn't affect correctness.
5486	*
5487	* WRITE_ONCE() is necessary because @worker->flags may be
5488	* tested without holding any lock in
5489	* wq_worker_running(). Without it, NOT_RUNNING test may
5490	* fail incorrectly leading to premature concurrency
5491	* management operations.
5492	*/
5493	WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND));
5494	worker_flags \|= WORKER_REBOUND;
5495	worker_flags &= ~WORKER_UNBOUND;
5496	WRITE_ONCE(worker->flags, worker_flags);
5497	}
5498
5499	raw_spin_unlock_irq(&pool->lock);
5500	}
5501
5502	/**
5503	* restore_unbound_workers_cpumask - restore cpumask of unbound workers
5504	* @pool: unbound pool of interest
5505	* @cpu: the CPU which is coming up
5506	*
5507	* An unbound pool may end up with a cpumask which doesn't have any online
5508	* CPUs. When a worker of such pool get scheduled, the scheduler resets
5509	* its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
5510	* online CPU before, cpus_allowed of all its workers should be restored.
5511	*/
5512	static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
5513	{
5514	static cpumask_t cpumask;
5515	struct worker *worker;
5516
5517	lockdep_assert_held(&wq_pool_attach_mutex);
5518
5519	/* is @cpu allowed for @pool? */
5520	if (!cpumask_test_cpu(cpu, pool->attrs->cpumask))
5521	return;
5522
5523	cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask);
5524
5525	/* as we're called from CPU_ONLINE, the following shouldn't fail */
5526	for_each_pool_worker(worker, pool)
5527	WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0);
5528	}
5529
5530	int workqueue_prepare_cpu(unsigned int cpu)
5531	{
5532	struct worker_pool *pool;
5533
5534	for_each_cpu_worker_pool(pool, cpu) {
5535	if (pool->nr_workers)
5536	continue;
5537	if (!create_worker(pool))
5538	return -ENOMEM;
5539	}
5540	return 0;
5541	}
5542
5543	int workqueue_online_cpu(unsigned int cpu)
5544	{
5545	struct worker_pool *pool;
5546	struct workqueue_struct *wq;
5547	int pi;
5548
5549	mutex_lock(&wq_pool_mutex);
5550
5551	for_each_pool(pool, pi) {
5552	mutex_lock(&wq_pool_attach_mutex);
5553
5554	if (pool->cpu == cpu)
5555	rebind_workers(pool);
5556	else if (pool->cpu < 0)
5557	restore_unbound_workers_cpumask(pool, cpu);
5558
5559	mutex_unlock(&wq_pool_attach_mutex);
5560	}
5561
5562	/* update pod affinity of unbound workqueues */
5563	list_for_each_entry(wq, &workqueues, list) {
5564	struct workqueue_attrs *attrs = wq->unbound_attrs;
5565
5566	if (attrs) {
5567	const struct wq_pod_type *pt = wqattrs_pod_type(attrs);
5568	int tcpu;
5569
5570	for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]])
5571	wq_update_pod(wq, tcpu, cpu, true);
5572	}
5573	}
5574
5575	mutex_unlock(&wq_pool_mutex);
5576	return 0;
5577	}
5578
5579	int workqueue_offline_cpu(unsigned int cpu)
5580	{
5581	struct workqueue_struct *wq;
5582
5583	/* unbinding per-cpu workers should happen on the local CPU */
5584	if (WARN_ON(cpu != smp_processor_id()))
5585	return -1;
5586
5587	unbind_workers(cpu);
5588
5589	/* update pod affinity of unbound workqueues */
5590	mutex_lock(&wq_pool_mutex);
5591	list_for_each_entry(wq, &workqueues, list) {
5592	struct workqueue_attrs *attrs = wq->unbound_attrs;
5593
5594	if (attrs) {
5595	const struct wq_pod_type *pt = wqattrs_pod_type(attrs);
5596	int tcpu;
5597
5598	for_each_cpu(tcpu, pt->pod_cpus[pt->cpu_pod[cpu]])
5599	wq_update_pod(wq, tcpu, cpu, false);
5600	}
5601	}
5602	mutex_unlock(&wq_pool_mutex);
5603
5604	return 0;
5605	}
5606
5607	struct work_for_cpu {
5608	struct work_struct work;
5609	long (fn)(void );
5610	void *arg;
5611	long ret;
5612	};
5613
5614	static void work_for_cpu_fn(struct work_struct *work)
5615	{
5616	struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work);
5617
5618	wfc->ret = wfc->fn(wfc->arg);
5619	}
5620
5621	/**
5622	* work_on_cpu_key - run a function in thread context on a particular cpu
5623	* @cpu: the cpu to run on
5624	* @fn: the function to run
5625	* @arg: the function arg
5626	* @key: The lock class key for lock debugging purposes
5627	*
5628	* It is up to the caller to ensure that the cpu doesn't go offline.
5629	* The caller must not hold any locks which would prevent @fn from completing.
5630	*
5631	* Return: The value @fn returns.
5632	*/
5633	long work_on_cpu_key(int cpu, long (fn)(void ),
5634	void arg, struct lock_class_key key)
5635	{
5636	struct work_for_cpu wfc = { .fn = fn, .arg = arg };
5637
5638	INIT_WORK_ONSTACK_KEY(&wfc.work, work_for_cpu_fn, key);
5639	schedule_work_on(cpu, &wfc.work);
5640	flush_work(&wfc.work);
5641	destroy_work_on_stack(&wfc.work);
5642	return wfc.ret;
5643	}
5644	EXPORT_SYMBOL_GPL(work_on_cpu_key);
5645
5646	/**
5647	* work_on_cpu_safe_key - run a function in thread context on a particular cpu
5648	* @cpu: the cpu to run on
5649	* @fn: the function to run
5650	* @arg: the function argument
5651	* @key: The lock class key for lock debugging purposes
5652	*
5653	* Disables CPU hotplug and calls work_on_cpu(). The caller must not hold
5654	* any locks which would prevent @fn from completing.
5655	*
5656	* Return: The value @fn returns.
5657	*/
5658	long work_on_cpu_safe_key(int cpu, long (fn)(void ),
5659	void arg, struct lock_class_key key)
5660	{
5661	long ret = -ENODEV;
5662
5663	cpus_read_lock();
5664	if (cpu_online(cpu))
5665	ret = work_on_cpu_key(cpu, fn, arg, key);
5666	cpus_read_unlock();
5667	return ret;
5668	}
5669	EXPORT_SYMBOL_GPL(work_on_cpu_safe_key);
5670	#endif /* CONFIG_SMP */
5671
5672	#ifdef CONFIG_FREEZER
5673
5674	/**
5675	* freeze_workqueues_begin - begin freezing workqueues
5676	*
5677	* Start freezing workqueues. After this function returns, all freezable
5678	* workqueues will queue new works to their inactive_works list instead of
5679	* pool->worklist.
5680	*
5681	* CONTEXT:
5682	* Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
5683	*/
5684	void freeze_workqueues_begin(void)
5685	{
5686	struct workqueue_struct *wq;
5687	struct pool_workqueue *pwq;
5688
5689	mutex_lock(&wq_pool_mutex);
5690
5691	WARN_ON_ONCE(workqueue_freezing);
5692	workqueue_freezing = true;
5693
5694	list_for_each_entry(wq, &workqueues, list) {
5695	mutex_lock(&wq->mutex);
5696	for_each_pwq(pwq, wq)
5697	pwq_adjust_max_active(pwq);
5698	mutex_unlock(&wq->mutex);
5699	}
5700
5701	mutex_unlock(&wq_pool_mutex);
5702	}
5703
5704	/**
5705	* freeze_workqueues_busy - are freezable workqueues still busy?
5706	*
5707	* Check whether freezing is complete. This function must be called
5708	* between freeze_workqueues_begin() and thaw_workqueues().
5709	*
5710	* CONTEXT:
5711	* Grabs and releases wq_pool_mutex.
5712	*
5713	* Return:
5714	* %true if some freezable workqueues are still busy. %false if freezing
5715	* is complete.
5716	*/
5717	bool freeze_workqueues_busy(void)
5718	{
5719	bool busy = false;
5720	struct workqueue_struct *wq;
5721	struct pool_workqueue *pwq;
5722
5723	mutex_lock(&wq_pool_mutex);
5724
5725	WARN_ON_ONCE(!workqueue_freezing);
5726
5727	list_for_each_entry(wq, &workqueues, list) {
5728	if (!(wq->flags & WQ_FREEZABLE))
5729	continue;
5730	/*
5731	* nr_active is monotonically decreasing. It's safe
5732	* to peek without lock.
5733	*/
5734	rcu_read_lock();
5735	for_each_pwq(pwq, wq) {
5736	WARN_ON_ONCE(pwq->nr_active < 0);
5737	if (pwq->nr_active) {
5738	busy = true;
5739	rcu_read_unlock();
5740	goto out_unlock;
5741	}
5742	}
5743	rcu_read_unlock();
5744	}
5745	out_unlock:
5746	mutex_unlock(&wq_pool_mutex);
5747	return busy;
5748	}
5749
5750	/**
5751	* thaw_workqueues - thaw workqueues
5752	*
5753	* Thaw workqueues. Normal queueing is restored and all collected
5754	* frozen works are transferred to their respective pool worklists.
5755	*
5756	* CONTEXT:
5757	* Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
5758	*/
5759	void thaw_workqueues(void)
5760	{
5761	struct workqueue_struct *wq;
5762	struct pool_workqueue *pwq;
5763
5764	mutex_lock(&wq_pool_mutex);
5765
5766	if (!workqueue_freezing)
5767	goto out_unlock;
5768
5769	workqueue_freezing = false;
5770
5771	/* restore max_active and repopulate worklist */
5772	list_for_each_entry(wq, &workqueues, list) {
5773	mutex_lock(&wq->mutex);
5774	for_each_pwq(pwq, wq)
5775	pwq_adjust_max_active(pwq);
5776	mutex_unlock(&wq->mutex);
5777	}
5778
5779	out_unlock:
5780	mutex_unlock(&wq_pool_mutex);
5781	}
5782	#endif /* CONFIG_FREEZER */
5783
5784	static int workqueue_apply_unbound_cpumask(const cpumask_var_t unbound_cpumask)
5785	{
5786	LIST_HEAD(ctxs);
5787	int ret = 0;
5788	struct workqueue_struct *wq;
5789	struct apply_wqattrs_ctx ctx, n;
5790
5791	lockdep_assert_held(&wq_pool_mutex);
5792
5793	list_for_each_entry(wq, &workqueues, list) {
5794	if (!(wq->flags & WQ_UNBOUND))
5795	continue;
5796
5797	/* creating multiple pwqs breaks ordering guarantee */
5798	if (!list_empty(&wq->pwqs)) {
5799	if (wq->flags & __WQ_ORDERED_EXPLICIT)
5800	continue;
5801	wq->flags &= ~__WQ_ORDERED;
5802	}
5803
5804	ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs, unbound_cpumask);
5805	if (IS_ERR(ctx)) {
5806	ret = PTR_ERR(ctx);
5807	break;
5808	}
5809
5810	list_add_tail(&ctx->list, &ctxs);
5811	}
5812
5813	list_for_each_entry_safe(ctx, n, &ctxs, list) {
5814	if (!ret)
5815	apply_wqattrs_commit(ctx);
5816	apply_wqattrs_cleanup(ctx);
5817	}
5818
5819	if (!ret) {
5820	mutex_lock(&wq_pool_attach_mutex);
5821	cpumask_copy(wq_unbound_cpumask, unbound_cpumask);
5822	mutex_unlock(&wq_pool_attach_mutex);
5823	}
5824	return ret;
5825	}
5826
5827	/**
5828	* workqueue_set_unbound_cpumask - Set the low-level unbound cpumask
5829	* @cpumask: the cpumask to set
5830	*
5831	* The low-level workqueues cpumask is a global cpumask that limits
5832	* the affinity of all unbound workqueues. This function check the @cpumask
5833	* and apply it to all unbound workqueues and updates all pwqs of them.
5834	*
5835	* Return: 0 - Success
5836	* -EINVAL - Invalid @cpumask
5837	* -ENOMEM - Failed to allocate memory for attrs or pwqs.
5838	*/
5839	int workqueue_set_unbound_cpumask(cpumask_var_t cpumask)
5840	{
5841	int ret = -EINVAL;
5842
5843	/*
5844	* Not excluding isolated cpus on purpose.
5845	* If the user wishes to include them, we allow that.
5846	*/
5847	cpumask_and(cpumask, cpumask, cpu_possible_mask);
5848	if (!cpumask_empty(cpumask)) {
5849	apply_wqattrs_lock();
5850	if (cpumask_equal(cpumask, wq_unbound_cpumask)) {
5851	ret = 0;
5852	goto out_unlock;
5853	}
5854
5855	ret = workqueue_apply_unbound_cpumask(cpumask);
5856
5857	out_unlock:
5858	apply_wqattrs_unlock();
5859	}
5860
5861	return ret;
5862	}
5863
5864	static int parse_affn_scope(const char *val)
5865	{
5866	int i;
5867
5868	for (i = 0; i < ARRAY_SIZE(wq_affn_names); i++) {
5869	if (!strncasecmp(val, wq_affn_names[i], strlen(wq_affn_names[i])))
5870	return i;
5871	}
5872	return -EINVAL;
5873	}
5874
5875	static int wq_affn_dfl_set(const char val, const struct kernel_param kp)
5876	{
5877	struct workqueue_struct *wq;
5878	int affn, cpu;
5879
5880	affn = parse_affn_scope(val);
5881	if (affn < 0)
5882	return affn;
5883	if (affn == WQ_AFFN_DFL)
5884	return -EINVAL;
5885
5886	cpus_read_lock();
5887	mutex_lock(&wq_pool_mutex);
5888
5889	wq_affn_dfl = affn;
5890
5891	list_for_each_entry(wq, &workqueues, list) {
5892	for_each_online_cpu(cpu) {
5893	wq_update_pod(wq, cpu, cpu, true);
5894	}
5895	}
5896
5897	mutex_unlock(&wq_pool_mutex);
5898	cpus_read_unlock();
5899
5900	return 0;
5901	}
5902
5903	static int wq_affn_dfl_get(char buffer, const struct kernel_param kp)
5904	{
5905	return scnprintf(buffer, PAGE_SIZE, "%s\n", wq_affn_names[wq_affn_dfl]);
5906	}
5907
5908	static const struct kernel_param_ops wq_affn_dfl_ops = {
5909	.set = wq_affn_dfl_set,
5910	.get = wq_affn_dfl_get,
5911	};
5912
5913	module_param_cb(default_affinity_scope, &wq_affn_dfl_ops, NULL, 0644);
5914
5915	#ifdef CONFIG_SYSFS
5916	/*
5917	* Workqueues with WQ_SYSFS flag set is visible to userland via
5918	* /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
5919	* following attributes.
5920	*
5921	* per_cpu RO bool : whether the workqueue is per-cpu or unbound
5922	* max_active RW int : maximum number of in-flight work items
5923	*
5924	* Unbound workqueues have the following extra attributes.
5925	*
5926	* nice RW int : nice value of the workers
5927	* cpumask RW mask : bitmask of allowed CPUs for the workers
5928	* affinity_scope RW str : worker CPU affinity scope (cache, numa, none)
5929	* affinity_strict RW bool : worker CPU affinity is strict
5930	*/
5931	struct wq_device {
5932	struct workqueue_struct *wq;
5933	struct device dev;
5934	};
5935
5936	static struct workqueue_struct dev_to_wq(struct device dev)
5937	{
5938	struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
5939
5940	return wq_dev->wq;
5941	}
5942
5943	static ssize_t per_cpu_show(struct device dev, struct device_attribute attr,
5944	char *buf)
5945	{
5946	struct workqueue_struct *wq = dev_to_wq(dev);
5947
5948	return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND));
5949	}
5950	static DEVICE_ATTR_RO(per_cpu);
5951
5952	static ssize_t max_active_show(struct device *dev,
5953	struct device_attribute attr, char buf)
5954	{
5955	struct workqueue_struct *wq = dev_to_wq(dev);
5956
5957	return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active);
5958	}
5959
5960	static ssize_t max_active_store(struct device *dev,
5961	struct device_attribute attr, const char buf,
5962	size_t count)
5963	{
5964	struct workqueue_struct *wq = dev_to_wq(dev);
5965	int val;
5966
5967	if (sscanf(buf, "%d", &val) != 1 \|\| val <= 0)
5968	return -EINVAL;
5969
5970	workqueue_set_max_active(wq, val);
5971	return count;
5972	}
5973	static DEVICE_ATTR_RW(max_active);
5974
5975	static struct attribute *wq_sysfs_attrs[] = {
5976	&dev_attr_per_cpu.attr,
5977	&dev_attr_max_active.attr,
5978	NULL,
5979	};
5980	ATTRIBUTE_GROUPS(wq_sysfs);
5981
5982	static ssize_t wq_nice_show(struct device dev, struct device_attribute attr,
5983	char *buf)
5984	{
5985	struct workqueue_struct *wq = dev_to_wq(dev);
5986	int written;
5987
5988	mutex_lock(&wq->mutex);
5989	written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice);
5990	mutex_unlock(&wq->mutex);
5991
5992	return written;
5993	}
5994
5995	/* prepare workqueue_attrs for sysfs store operations */
5996	static struct workqueue_attrs wq_sysfs_prep_attrs(struct workqueue_struct wq)
5997	{
5998	struct workqueue_attrs *attrs;
5999
6000	lockdep_assert_held(&wq_pool_mutex);
6001
6002	attrs = alloc_workqueue_attrs();
6003	if (!attrs)
6004	return NULL;
6005
6006	copy_workqueue_attrs(attrs, wq->unbound_attrs);
6007	return attrs;
6008	}
6009
6010	static ssize_t wq_nice_store(struct device dev, struct device_attribute attr,
6011	const char *buf, size_t count)
6012	{
6013	struct workqueue_struct *wq = dev_to_wq(dev);
6014	struct workqueue_attrs *attrs;
6015	int ret = -ENOMEM;
6016
6017	apply_wqattrs_lock();
6018
6019	attrs = wq_sysfs_prep_attrs(wq);
6020	if (!attrs)
6021	goto out_unlock;
6022
6023	if (sscanf(buf, "%d", &attrs->nice) == 1 &&
6024	attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE)
6025	ret = apply_workqueue_attrs_locked(wq, attrs);
6026	else
6027	ret = -EINVAL;
6028
6029	out_unlock:
6030	apply_wqattrs_unlock();
6031	free_workqueue_attrs(attrs);
6032	return ret ?: count;
6033	}
6034
6035	static ssize_t wq_cpumask_show(struct device *dev,
6036	struct device_attribute attr, char buf)
6037	{
6038	struct workqueue_struct *wq = dev_to_wq(dev);
6039	int written;
6040
6041	mutex_lock(&wq->mutex);
6042	written = scnprintf(buf, PAGE_SIZE, "%*pb\n",
6043	cpumask_pr_args(wq->unbound_attrs->cpumask));
6044	mutex_unlock(&wq->mutex);
6045	return written;
6046	}
6047
6048	static ssize_t wq_cpumask_store(struct device *dev,
6049	struct device_attribute *attr,
6050	const char *buf, size_t count)
6051	{
6052	struct workqueue_struct *wq = dev_to_wq(dev);
6053	struct workqueue_attrs *attrs;
6054	int ret = -ENOMEM;
6055
6056	apply_wqattrs_lock();
6057
6058	attrs = wq_sysfs_prep_attrs(wq);
6059	if (!attrs)
6060	goto out_unlock;
6061
6062	ret = cpumask_parse(buf, attrs->cpumask);
6063	if (!ret)
6064	ret = apply_workqueue_attrs_locked(wq, attrs);
6065
6066	out_unlock:
6067	apply_wqattrs_unlock();
6068	free_workqueue_attrs(attrs);
6069	return ret ?: count;
6070	}
6071
6072	static ssize_t wq_affn_scope_show(struct device *dev,
6073	struct device_attribute attr, char buf)
6074	{
6075	struct workqueue_struct *wq = dev_to_wq(dev);
6076	int written;
6077
6078	mutex_lock(&wq->mutex);
6079	if (wq->unbound_attrs->affn_scope == WQ_AFFN_DFL)
6080	written = scnprintf(buf, PAGE_SIZE, "%s (%s)\n",
6081	wq_affn_names[WQ_AFFN_DFL],
6082	wq_affn_names[wq_affn_dfl]);
6083	else
6084	written = scnprintf(buf, PAGE_SIZE, "%s\n",
6085	wq_affn_names[wq->unbound_attrs->affn_scope]);
6086	mutex_unlock(&wq->mutex);
6087
6088	return written;
6089	}
6090
6091	static ssize_t wq_affn_scope_store(struct device *dev,
6092	struct device_attribute *attr,
6093	const char *buf, size_t count)
6094	{
6095	struct workqueue_struct *wq = dev_to_wq(dev);
6096	struct workqueue_attrs *attrs;
6097	int affn, ret = -ENOMEM;
6098
6099	affn = parse_affn_scope(buf);
6100	if (affn < 0)
6101	return affn;
6102
6103	apply_wqattrs_lock();
6104	attrs = wq_sysfs_prep_attrs(wq);
6105	if (attrs) {
6106	attrs->affn_scope = affn;
6107	ret = apply_workqueue_attrs_locked(wq, attrs);
6108	}
6109	apply_wqattrs_unlock();
6110	free_workqueue_attrs(attrs);
6111	return ret ?: count;
6112	}
6113
6114	static ssize_t wq_affinity_strict_show(struct device *dev,
6115	struct device_attribute attr, char buf)
6116	{
6117	struct workqueue_struct *wq = dev_to_wq(dev);
6118
6119	return scnprintf(buf, PAGE_SIZE, "%d\n",
6120	wq->unbound_attrs->affn_strict);
6121	}
6122
6123	static ssize_t wq_affinity_strict_store(struct device *dev,
6124	struct device_attribute *attr,
6125	const char *buf, size_t count)
6126	{
6127	struct workqueue_struct *wq = dev_to_wq(dev);
6128	struct workqueue_attrs *attrs;
6129	int v, ret = -ENOMEM;
6130
6131	if (sscanf(buf, "%d", &v) != 1)
6132	return -EINVAL;
6133
6134	apply_wqattrs_lock();
6135	attrs = wq_sysfs_prep_attrs(wq);
6136	if (attrs) {
6137	attrs->affn_strict = (bool)v;
6138	ret = apply_workqueue_attrs_locked(wq, attrs);
6139	}
6140	apply_wqattrs_unlock();
6141	free_workqueue_attrs(attrs);
6142	return ret ?: count;
6143	}
6144
6145	static struct device_attribute wq_sysfs_unbound_attrs[] = {
6146	__ATTR(nice, 0644, wq_nice_show, wq_nice_store),
6147	__ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store),
6148	__ATTR(affinity_scope, 0644, wq_affn_scope_show, wq_affn_scope_store),
6149	__ATTR(affinity_strict, 0644, wq_affinity_strict_show, wq_affinity_strict_store),
6150	__ATTR_NULL,
6151	};
6152
6153	static struct bus_type wq_subsys = {
6154	.name = "workqueue",
6155	.dev_groups = wq_sysfs_groups,
6156	};
6157
6158	static ssize_t wq_unbound_cpumask_show(struct device *dev,
6159	struct device_attribute attr, char buf)
6160	{
6161	int written;
6162
6163	mutex_lock(&wq_pool_mutex);
6164	written = scnprintf(buf, PAGE_SIZE, "%*pb\n",
6165	cpumask_pr_args(wq_unbound_cpumask));
6166	mutex_unlock(&wq_pool_mutex);
6167
6168	return written;
6169	}
6170
6171	static ssize_t wq_unbound_cpumask_store(struct device *dev,
6172	struct device_attribute attr, const char buf, size_t count)
6173	{
6174	cpumask_var_t cpumask;
6175	int ret;
6176
6177	if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL))
6178	return -ENOMEM;
6179
6180	ret = cpumask_parse(buf, cpumask);
6181	if (!ret)
6182	ret = workqueue_set_unbound_cpumask(cpumask);
6183
6184	free_cpumask_var(cpumask);
6185	return ret ? ret : count;
6186	}
6187
6188	static struct device_attribute wq_sysfs_cpumask_attr =
6189	__ATTR(cpumask, 0644, wq_unbound_cpumask_show,
6190	wq_unbound_cpumask_store);
6191
6192	static int __init wq_sysfs_init(void)
6193	{
6194	struct device *dev_root;
6195	int err;
6196
6197	err = subsys_virtual_register(&wq_subsys, NULL);
6198	if (err)
6199	return err;
6200
6201	dev_root = bus_get_dev_root(&wq_subsys);
6202	if (dev_root) {
6203	err = device_create_file(dev_root, &wq_sysfs_cpumask_attr);
6204	put_device(dev_root);
6205	}
6206	return err;
6207	}
6208	core_initcall(wq_sysfs_init);
6209
6210	static void wq_device_release(struct device *dev)
6211	{
6212	struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
6213
6214	kfree(wq_dev);
6215	}
6216
6217	/**
6218	* workqueue_sysfs_register - make a workqueue visible in sysfs
6219	* @wq: the workqueue to register
6220	*
6221	* Expose @wq in sysfs under /sys/bus/workqueue/devices.
6222	* alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
6223	* which is the preferred method.
6224	*
6225	* Workqueue user should use this function directly iff it wants to apply
6226	* workqueue_attrs before making the workqueue visible in sysfs; otherwise,
6227	* apply_workqueue_attrs() may race against userland updating the
6228	* attributes.
6229	*
6230	* Return: 0 on success, -errno on failure.
6231	*/
6232	int workqueue_sysfs_register(struct workqueue_struct *wq)
6233	{
6234	struct wq_device *wq_dev;
6235	int ret;
6236
6237	/*
6238	* Adjusting max_active or creating new pwqs by applying
6239	* attributes breaks ordering guarantee. Disallow exposing ordered
6240	* workqueues.
6241	*/
6242	if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT))
6243	return -EINVAL;
6244
6245	wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL);
6246	if (!wq_dev)
6247	return -ENOMEM;
6248
6249	wq_dev->wq = wq;
6250	wq_dev->dev.bus = &wq_subsys;
6251	wq_dev->dev.release = wq_device_release;
6252	dev_set_name(&wq_dev->dev, "%s", wq->name);
6253
6254	/*
6255	* unbound_attrs are created separately. Suppress uevent until
6256	* everything is ready.
6257	*/
6258	dev_set_uevent_suppress(&wq_dev->dev, true);
6259
6260	ret = device_register(&wq_dev->dev);
6261	if (ret) {
6262	put_device(&wq_dev->dev);
6263	wq->wq_dev = NULL;
6264	return ret;
6265	}
6266
6267	if (wq->flags & WQ_UNBOUND) {
6268	struct device_attribute *attr;
6269
6270	for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) {
6271	ret = device_create_file(&wq_dev->dev, attr);
6272	if (ret) {
6273	device_unregister(&wq_dev->dev);
6274	wq->wq_dev = NULL;
6275	return ret;
6276	}
6277	}
6278	}
6279
6280	dev_set_uevent_suppress(&wq_dev->dev, false);
6281	kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD);
6282	return 0;
6283	}
6284
6285	/**
6286	* workqueue_sysfs_unregister - undo workqueue_sysfs_register()
6287	* @wq: the workqueue to unregister
6288	*
6289	* If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
6290	*/
6291	static void workqueue_sysfs_unregister(struct workqueue_struct *wq)
6292	{
6293	struct wq_device *wq_dev = wq->wq_dev;
6294
6295	if (!wq->wq_dev)
6296	return;
6297
6298	wq->wq_dev = NULL;
6299	device_unregister(&wq_dev->dev);
6300	}
6301	#else /* CONFIG_SYSFS */
6302	static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { }
6303	#endif /* CONFIG_SYSFS */
6304
6305	/*
6306	* Workqueue watchdog.
6307	*
6308	* Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal
6309	* flush dependency, a concurrency managed work item which stays RUNNING
6310	* indefinitely. Workqueue stalls can be very difficult to debug as the
6311	* usual warning mechanisms don't trigger and internal workqueue state is
6312	* largely opaque.
6313	*
6314	* Workqueue watchdog monitors all worker pools periodically and dumps
6315	* state if some pools failed to make forward progress for a while where
6316	* forward progress is defined as the first item on ->worklist changing.
6317	*
6318	* This mechanism is controlled through the kernel parameter
6319	* "workqueue.watchdog_thresh" which can be updated at runtime through the
6320	* corresponding sysfs parameter file.
6321	*/
6322	#ifdef CONFIG_WQ_WATCHDOG
6323
6324	static unsigned long wq_watchdog_thresh = 30;
6325	static struct timer_list wq_watchdog_timer;
6326
6327	static unsigned long wq_watchdog_touched = INITIAL_JIFFIES;
6328	static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES;
6329
6330	/*
6331	* Show workers that might prevent the processing of pending work items.
6332	* The only candidates are CPU-bound workers in the running state.
6333	* Pending work items should be handled by another idle worker
6334	* in all other situations.
6335	*/
6336	static void show_cpu_pool_hog(struct worker_pool *pool)
6337	{
6338	struct worker *worker;
6339	unsigned long flags;
6340	int bkt;
6341
6342	raw_spin_lock_irqsave(&pool->lock, flags);
6343
6344	hash_for_each(pool->busy_hash, bkt, worker, hentry) {
6345	if (task_is_running(worker->task)) {
6346	/*
6347	* Defer printing to avoid deadlocks in console
6348	* drivers that queue work while holding locks
6349	* also taken in their write paths.
6350	*/
6351	printk_deferred_enter();
6352
6353	pr_info("pool %d:\n", pool->id);
6354	sched_show_task(worker->task);
6355
6356	printk_deferred_exit();
6357	}
6358	}
6359
6360	raw_spin_unlock_irqrestore(&pool->lock, flags);
6361	}
6362
6363	static void show_cpu_pools_hogs(void)
6364	{
6365	struct worker_pool *pool;
6366	int pi;
6367
6368	pr_info("Showing backtraces of running workers in stalled CPU-bound worker pools:\n");
6369
6370	rcu_read_lock();
6371
6372	for_each_pool(pool, pi) {
6373	if (pool->cpu_stall)
6374	show_cpu_pool_hog(pool);
6375
6376	}
6377
6378	rcu_read_unlock();
6379	}
6380
6381	static void wq_watchdog_reset_touched(void)
6382	{
6383	int cpu;
6384
6385	wq_watchdog_touched = jiffies;
6386	for_each_possible_cpu(cpu)
6387	per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies;
6388	}
6389
6390	static void wq_watchdog_timer_fn(struct timer_list *unused)
6391	{
6392	unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ;
6393	bool lockup_detected = false;
6394	bool cpu_pool_stall = false;
6395	unsigned long now = jiffies;
6396	struct worker_pool *pool;
6397	int pi;
6398
6399	if (!thresh)
6400	return;
6401
6402	rcu_read_lock();
6403
6404	for_each_pool(pool, pi) {
6405	unsigned long pool_ts, touched, ts;
6406
6407	pool->cpu_stall = false;
6408	if (list_empty(&pool->worklist))
6409	continue;
6410
6411	/*
6412	* If a virtual machine is stopped by the host it can look to
6413	* the watchdog like a stall.
6414	*/
6415	kvm_check_and_clear_guest_paused();
6416
6417	/* get the latest of pool and touched timestamps */
6418	if (pool->cpu >= 0)
6419	touched = READ_ONCE(per_cpu(wq_watchdog_touched_cpu, pool->cpu));
6420	else
6421	touched = READ_ONCE(wq_watchdog_touched);
6422	pool_ts = READ_ONCE(pool->watchdog_ts);
6423
6424	if (time_after(pool_ts, touched))
6425	ts = pool_ts;
6426	else
6427	ts = touched;
6428
6429	/* did we stall? */
6430	if (time_after(now, ts + thresh)) {
6431	lockup_detected = true;
6432	if (pool->cpu >= 0) {
6433	pool->cpu_stall = true;
6434	cpu_pool_stall = true;
6435	}
6436	pr_emerg("BUG: workqueue lockup - pool");
6437	pr_cont_pool_info(pool);
6438	pr_cont(" stuck for %us!\n",
6439	jiffies_to_msecs(now - pool_ts) / 1000);
6440	}
6441
6442
6443	}
6444
6445	rcu_read_unlock();
6446
6447	if (lockup_detected)
6448	show_all_workqueues();
6449
6450	if (cpu_pool_stall)
6451	show_cpu_pools_hogs();
6452
6453	wq_watchdog_reset_touched();
6454	mod_timer(&wq_watchdog_timer, jiffies + thresh);
6455	}
6456
6457	notrace void wq_watchdog_touch(int cpu)
6458	{
6459	if (cpu >= 0)
6460	per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies;
6461
6462	wq_watchdog_touched = jiffies;
6463	}
6464
6465	static void wq_watchdog_set_thresh(unsigned long thresh)
6466	{
6467	wq_watchdog_thresh = 0;
6468	del_timer_sync(&wq_watchdog_timer);
6469
6470	if (thresh) {
6471	wq_watchdog_thresh = thresh;
6472	wq_watchdog_reset_touched();
6473	mod_timer(&wq_watchdog_timer, jiffies + thresh * HZ);
6474	}
6475	}
6476
6477	static int wq_watchdog_param_set_thresh(const char *val,
6478	const struct kernel_param *kp)
6479	{
6480	unsigned long thresh;
6481	int ret;
6482
6483	ret = kstrtoul(val, 0, &thresh);
6484	if (ret)
6485	return ret;
6486
6487	if (system_wq)
6488	wq_watchdog_set_thresh(thresh);
6489	else
6490	wq_watchdog_thresh = thresh;
6491
6492	return 0;
6493	}
6494
6495	static const struct kernel_param_ops wq_watchdog_thresh_ops = {
6496	.set = wq_watchdog_param_set_thresh,
6497	.get = param_get_ulong,
6498	};
6499
6500	module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh,
6501	0644);
6502
6503	static void wq_watchdog_init(void)
6504	{
6505	timer_setup(&wq_watchdog_timer, wq_watchdog_timer_fn, TIMER_DEFERRABLE);
6506	wq_watchdog_set_thresh(wq_watchdog_thresh);
6507	}
6508
6509	#else /* CONFIG_WQ_WATCHDOG */
6510
6511	static inline void wq_watchdog_init(void) { }
6512
6513	#endif /* CONFIG_WQ_WATCHDOG */
6514
6515	static void __init restrict_unbound_cpumask(const char name, const struct cpumask mask)
6516	{
6517	if (!cpumask_intersects(wq_unbound_cpumask, mask)) {
6518	pr_warn("workqueue: Restricting unbound_cpumask (%pb) with %s (%pb) leaves no CPU, ignoring\n",
6519	cpumask_pr_args(wq_unbound_cpumask), name, cpumask_pr_args(mask));
6520	return;
6521	}
6522
6523	cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, mask);
6524	}
6525
6526	/**
6527	* workqueue_init_early - early init for workqueue subsystem
6528	*
6529	* This is the first step of three-staged workqueue subsystem initialization and
6530	* invoked as soon as the bare basics - memory allocation, cpumasks and idr are
6531	* up. It sets up all the data structures and system workqueues and allows early
6532	* boot code to create workqueues and queue/cancel work items. Actual work item
6533	* execution starts only after kthreads can be created and scheduled right
6534	* before early initcalls.
6535	*/
6536	void __init workqueue_init_early(void)
6537	{
6538	struct wq_pod_type *pt = &wq_pod_types[WQ_AFFN_SYSTEM];
6539	int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL };
6540	int i, cpu;
6541
6542	BUILD_BUG_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
6543
6544	BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL));
6545	cpumask_copy(wq_unbound_cpumask, cpu_possible_mask);
6546	restrict_unbound_cpumask("HK_TYPE_WQ", housekeeping_cpumask(HK_TYPE_WQ));
6547	restrict_unbound_cpumask("HK_TYPE_DOMAIN", housekeeping_cpumask(HK_TYPE_DOMAIN));
6548	if (!cpumask_empty(&wq_cmdline_cpumask))
6549	restrict_unbound_cpumask("workqueue.unbound_cpus", &wq_cmdline_cpumask);
6550
6551	pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);
6552
6553	wq_update_pod_attrs_buf = alloc_workqueue_attrs();
6554	BUG_ON(!wq_update_pod_attrs_buf);
6555
6556	/* initialize WQ_AFFN_SYSTEM pods */
6557	pt->pod_cpus = kcalloc(1, sizeof(pt->pod_cpus[0]), GFP_KERNEL);
6558	pt->pod_node = kcalloc(1, sizeof(pt->pod_node[0]), GFP_KERNEL);
6559	pt->cpu_pod = kcalloc(nr_cpu_ids, sizeof(pt->cpu_pod[0]), GFP_KERNEL);
6560	BUG_ON(!pt->pod_cpus \|\| !pt->pod_node \|\| !pt->cpu_pod);
6561
6562	BUG_ON(!zalloc_cpumask_var_node(&pt->pod_cpus[0], GFP_KERNEL, NUMA_NO_NODE));
6563
6564	pt->nr_pods = 1;
6565	cpumask_copy(pt->pod_cpus[0], cpu_possible_mask);
6566	pt->pod_node[0] = NUMA_NO_NODE;
6567	pt->cpu_pod[0] = 0;
6568
6569	/* initialize CPU pools */
6570	for_each_possible_cpu(cpu) {
6571	struct worker_pool *pool;
6572
6573	i = 0;
6574	for_each_cpu_worker_pool(pool, cpu) {
6575	BUG_ON(init_worker_pool(pool));
6576	pool->cpu = cpu;
6577	cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu));
6578	cpumask_copy(pool->attrs->__pod_cpumask, cpumask_of(cpu));
6579	pool->attrs->nice = std_nice[i++];
6580	pool->attrs->affn_strict = true;
6581	pool->node = cpu_to_node(cpu);
6582
6583	/* alloc pool ID */
6584	mutex_lock(&wq_pool_mutex);
6585	BUG_ON(worker_pool_assign_id(pool));
6586	mutex_unlock(&wq_pool_mutex);
6587	}
6588	}
6589
6590	/* create default unbound and ordered wq attrs */
6591	for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
6592	struct workqueue_attrs *attrs;
6593
6594	BUG_ON(!(attrs = alloc_workqueue_attrs()));
6595	attrs->nice = std_nice[i];
6596	unbound_std_wq_attrs[i] = attrs;
6597
6598	/*
6599	* An ordered wq should have only one pwq as ordering is
6600	* guaranteed by max_active which is enforced by pwqs.
6601	*/
6602	BUG_ON(!(attrs = alloc_workqueue_attrs()));
6603	attrs->nice = std_nice[i];
6604	attrs->ordered = true;
6605	ordered_wq_attrs[i] = attrs;
6606	}
6607
6608	system_wq = alloc_workqueue("events", 0, 0);
6609	system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0);
6610	system_long_wq = alloc_workqueue("events_long", 0, 0);
6611	system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
6612	WQ_MAX_ACTIVE);
6613	system_freezable_wq = alloc_workqueue("events_freezable",
6614	WQ_FREEZABLE, 0);
6615	system_power_efficient_wq = alloc_workqueue("events_power_efficient",
6616	WQ_POWER_EFFICIENT, 0);
6617	system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient",
6618	WQ_FREEZABLE \| WQ_POWER_EFFICIENT,
6619	0);
6620	BUG_ON(!system_wq \|\| !system_highpri_wq \|\| !system_long_wq \|\|
6621	!system_unbound_wq \|\| !system_freezable_wq \|\|
6622	!system_power_efficient_wq \|\|
6623	!system_freezable_power_efficient_wq);
6624	}
6625
6626	static void __init wq_cpu_intensive_thresh_init(void)
6627	{
6628	unsigned long thresh;
6629	unsigned long bogo;
6630
6631	pwq_release_worker = kthread_create_worker(0, "pool_workqueue_release");
6632	BUG_ON(IS_ERR(pwq_release_worker));
6633
6634	/* if the user set it to a specific value, keep it */
6635	if (wq_cpu_intensive_thresh_us != ULONG_MAX)
6636	return;
6637
6638	/*
6639	* The default of 10ms is derived from the fact that most modern (as of
6640	* 2023) processors can do a lot in 10ms and that it's just below what
6641	* most consider human-perceivable. However, the kernel also runs on a
6642	* lot slower CPUs including microcontrollers where the threshold is way
6643	* too low.
6644	*
6645	* Let's scale up the threshold upto 1 second if BogoMips is below 4000.
6646	* This is by no means accurate but it doesn't have to be. The mechanism
6647	* is still useful even when the threshold is fully scaled up. Also, as
6648	* the reports would usually be applicable to everyone, some machines
6649	* operating on longer thresholds won't significantly diminish their
6650	* usefulness.
6651	*/
6652	thresh = 10 * USEC_PER_MSEC;
6653
6654	/* see init/calibrate.c for lpj -> BogoMIPS calculation */
6655	bogo = max_t(unsigned long, loops_per_jiffy / 500000 * HZ, 1);
6656	if (bogo < 4000)
6657	thresh = min_t(unsigned long, thresh * 4000 / bogo, USEC_PER_SEC);
6658
6659	pr_debug("wq_cpu_intensive_thresh: lpj=%lu BogoMIPS=%lu thresh_us=%lu\n",
6660	loops_per_jiffy, bogo, thresh);
6661
6662	wq_cpu_intensive_thresh_us = thresh;
6663	}
6664
6665	/**
6666	* workqueue_init - bring workqueue subsystem fully online
6667	*
6668	* This is the second step of three-staged workqueue subsystem initialization
6669	* and invoked as soon as kthreads can be created and scheduled. Workqueues have
6670	* been created and work items queued on them, but there are no kworkers
6671	* executing the work items yet. Populate the worker pools with the initial
6672	* workers and enable future kworker creations.
6673	*/
6674	void __init workqueue_init(void)
6675	{
6676	struct workqueue_struct *wq;
6677	struct worker_pool *pool;
6678	int cpu, bkt;
6679
6680	wq_cpu_intensive_thresh_init();
6681
6682	mutex_lock(&wq_pool_mutex);
6683
6684	/*
6685	* Per-cpu pools created earlier could be missing node hint. Fix them
6686	* up. Also, create a rescuer for workqueues that requested it.
6687	*/
6688	for_each_possible_cpu(cpu) {
6689	for_each_cpu_worker_pool(pool, cpu) {
6690	pool->node = cpu_to_node(cpu);
6691	}
6692	}
6693
6694	list_for_each_entry(wq, &workqueues, list) {
6695	WARN(init_rescuer(wq),
6696	"workqueue: failed to create early rescuer for %s",
6697	wq->name);
6698	}
6699
6700	mutex_unlock(&wq_pool_mutex);
6701
6702	/* create the initial workers */
6703	for_each_online_cpu(cpu) {
6704	for_each_cpu_worker_pool(pool, cpu) {
6705	pool->flags &= ~POOL_DISASSOCIATED;
6706	BUG_ON(!create_worker(pool));
6707	}
6708	}
6709
6710	hash_for_each(unbound_pool_hash, bkt, pool, hash_node)
6711	BUG_ON(!create_worker(pool));
6712
6713	wq_online = true;
6714	wq_watchdog_init();
6715	}
6716
6717	/*
6718	* Initialize @pt by first initializing @pt->cpu_pod[] with pod IDs according to
6719	* @cpu_shares_pod(). Each subset of CPUs that share a pod is assigned a unique
6720	* and consecutive pod ID. The rest of @pt is initialized accordingly.
6721	*/
6722	static void __init init_pod_type(struct wq_pod_type *pt,
6723	bool (*cpus_share_pod)(int, int))
6724	{
6725	int cur, pre, cpu, pod;
6726
6727	pt->nr_pods = 0;
6728
6729	/* init @pt->cpu_pod[] according to @cpus_share_pod() */
6730	pt->cpu_pod = kcalloc(nr_cpu_ids, sizeof(pt->cpu_pod[0]), GFP_KERNEL);
6731	BUG_ON(!pt->cpu_pod);
6732
6733	for_each_possible_cpu(cur) {
6734	for_each_possible_cpu(pre) {
6735	if (pre >= cur) {
6736	pt->cpu_pod[cur] = pt->nr_pods++;
6737	break;
6738	}
6739	if (cpus_share_pod(cur, pre)) {
6740	pt->cpu_pod[cur] = pt->cpu_pod[pre];
6741	break;
6742	}
6743	}
6744	}
6745
6746	/* init the rest to match @pt->cpu_pod[] */
6747	pt->pod_cpus = kcalloc(pt->nr_pods, sizeof(pt->pod_cpus[0]), GFP_KERNEL);
6748	pt->pod_node = kcalloc(pt->nr_pods, sizeof(pt->pod_node[0]), GFP_KERNEL);
6749	BUG_ON(!pt->pod_cpus \|\| !pt->pod_node);
6750
6751	for (pod = 0; pod < pt->nr_pods; pod++)
6752	BUG_ON(!zalloc_cpumask_var(&pt->pod_cpus[pod], GFP_KERNEL));
6753
6754	for_each_possible_cpu(cpu) {
6755	cpumask_set_cpu(cpu, pt->pod_cpus[pt->cpu_pod[cpu]]);
6756	pt->pod_node[pt->cpu_pod[cpu]] = cpu_to_node(cpu);
6757	}
6758	}
6759
6760	static bool __init cpus_dont_share(int cpu0, int cpu1)
6761	{
6762	return false;
6763	}
6764
6765	static bool __init cpus_share_smt(int cpu0, int cpu1)
6766	{
6767	#ifdef CONFIG_SCHED_SMT
6768	return cpumask_test_cpu(cpu0, cpu_smt_mask(cpu1));
6769	#else
6770	return false;
6771	#endif
6772	}
6773
6774	static bool __init cpus_share_numa(int cpu0, int cpu1)
6775	{
6776	return cpu_to_node(cpu0) == cpu_to_node(cpu1);
6777	}
6778
6779	/**
6780	* workqueue_init_topology - initialize CPU pods for unbound workqueues
6781	*
6782	* This is the third step of there-staged workqueue subsystem initialization and
6783	* invoked after SMP and topology information are fully initialized. It
6784	* initializes the unbound CPU pods accordingly.
6785	*/
6786	void __init workqueue_init_topology(void)
6787	{
6788	struct workqueue_struct *wq;
6789	int cpu;
6790
6791	init_pod_type(&wq_pod_types[WQ_AFFN_CPU], cpus_dont_share);
6792	init_pod_type(&wq_pod_types[WQ_AFFN_SMT], cpus_share_smt);
6793	init_pod_type(&wq_pod_types[WQ_AFFN_CACHE], cpus_share_cache);
6794	init_pod_type(&wq_pod_types[WQ_AFFN_NUMA], cpus_share_numa);
6795
6796	mutex_lock(&wq_pool_mutex);
6797
6798	/*
6799	* Workqueues allocated earlier would have all CPUs sharing the default
6800	* worker pool. Explicitly call wq_update_pod() on all workqueue and CPU
6801	* combinations to apply per-pod sharing.
6802	*/
6803	list_for_each_entry(wq, &workqueues, list) {
6804	for_each_online_cpu(cpu) {
6805	wq_update_pod(wq, cpu, cpu, true);
6806	}
6807	}
6808
6809	mutex_unlock(&wq_pool_mutex);
6810	}
6811
6812	void __warn_flushing_systemwide_wq(void)
6813	{
6814	pr_warn("WARNING: Flushing system-wide workqueues will be prohibited in near future.\n");
6815	dump_stack();
6816	}
6817	EXPORT_SYMBOL(__warn_flushing_systemwide_wq);
6818
6819	static int __init workqueue_unbound_cpus_setup(char *str)
6820	{
6821	if (cpulist_parse(str, &wq_cmdline_cpumask) < 0) {
6822	cpumask_clear(&wq_cmdline_cpumask);
6823	pr_warn("workqueue.unbound_cpus: incorrect CPU range, using default\n");
6824	}
6825
6826	return 1;
6827	}
6828	__setup("workqueue.unbound_cpus=", workqueue_unbound_cpus_setup);