linux - kernel/workqueue.c

5986 lines · 163.8 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/nmi.h>
53
54	#include "workqueue_internal.h"
55
56	enum {
57	/*
58	* worker_pool flags
59	*
60	* A bound pool is either associated or disassociated with its CPU.
61	* While associated (!DISASSOCIATED), all workers are bound to the
62	* CPU and none has %WORKER_UNBOUND set and concurrency management
63	* is in effect.
64	*
65	* While DISASSOCIATED, the cpu may be offline and all workers have
66	* %WORKER_UNBOUND set and concurrency management disabled, and may
67	* be executing on any CPU. The pool behaves as an unbound one.
68	*
69	* Note that DISASSOCIATED should be flipped only while holding
70	* wq_pool_attach_mutex to avoid changing binding state while
71	* worker_attach_to_pool() is in progress.
72	*/
73	POOL_MANAGER_ACTIVE = 1 << 0, /* being managed */
74	POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */
75
76	/* worker flags */
77	WORKER_DIE = 1 << 1, /* die die die */
78	WORKER_IDLE = 1 << 2, /* is idle */
79	WORKER_PREP = 1 << 3, /* preparing to run works */
80	WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */
81	WORKER_UNBOUND = 1 << 7, /* worker is unbound */
82	WORKER_REBOUND = 1 << 8, /* worker was rebound */
83
84	WORKER_NOT_RUNNING = WORKER_PREP \| WORKER_CPU_INTENSIVE \|
85	WORKER_UNBOUND \| WORKER_REBOUND,
86
87	NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */
88
89	UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */
90	BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */
91
92	MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */
93	IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */
94
95	MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2,
96	/* call for help after 10ms
97	(min two ticks) */
98	MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */
99	CREATE_COOLDOWN = HZ, /* time to breath after fail */
100
101	/*
102	* Rescue workers are used only on emergencies and shared by
103	* all cpus. Give MIN_NICE.
104	*/
105	RESCUER_NICE_LEVEL = MIN_NICE,
106	HIGHPRI_NICE_LEVEL = MIN_NICE,
107
108	WQ_NAME_LEN = 24,
109	};
110
111	/*
112	* Structure fields follow one of the following exclusion rules.
113	*
114	* I: Modifiable by initialization/destruction paths and read-only for
115	* everyone else.
116	*
117	* P: Preemption protected. Disabling preemption is enough and should
118	* only be modified and accessed from the local cpu.
119	*
120	* L: pool->lock protected. Access with pool->lock held.
121	*
122	* X: During normal operation, modification requires pool->lock and should
123	* be done only from local cpu. Either disabling preemption on local
124	* cpu or grabbing pool->lock is enough for read access. If
125	* POOL_DISASSOCIATED is set, it's identical to L.
126	*
127	* A: wq_pool_attach_mutex protected.
128	*
129	* PL: wq_pool_mutex protected.
130	*
131	* PR: wq_pool_mutex protected for writes. RCU protected for reads.
132	*
133	* PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads.
134	*
135	* PWR: wq_pool_mutex and wq->mutex protected for writes. Either or
136	* RCU for reads.
137	*
138	* WQ: wq->mutex protected.
139	*
140	* WR: wq->mutex protected for writes. RCU protected for reads.
141	*
142	* MD: wq_mayday_lock protected.
143	*/
144
145	/* struct worker is defined in workqueue_internal.h */
146
147	struct worker_pool {
148	spinlock_t lock; /* the pool lock */
149	int cpu; /* I: the associated cpu */
150	int node; /* I: the associated node ID */
151	int id; /* I: pool ID */
152	unsigned int flags; /* X: flags */
153
154	unsigned long watchdog_ts; /* L: watchdog timestamp */
155
156	struct list_head worklist; /* L: list of pending works */
157
158	int nr_workers; /* L: total number of workers */
159	int nr_idle; /* L: currently idle workers */
160
161	struct list_head idle_list; /* X: list of idle workers */
162	struct timer_list idle_timer; /* L: worker idle timeout */
163	struct timer_list mayday_timer; /* L: SOS timer for workers */
164
165	/* a workers is either on busy_hash or idle_list, or the manager */
166	DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER);
167	/* L: hash of busy workers */
168
169	struct worker manager; / L: purely informational */
170	struct list_head workers; /* A: attached workers */
171	struct completion detach_completion; / all workers detached */
172
173	struct ida worker_ida; /* worker IDs for task name */
174
175	struct workqueue_attrs attrs; / I: worker attributes */
176	struct hlist_node hash_node; /* PL: unbound_pool_hash node */
177	int refcnt; /* PL: refcnt for unbound pools */
178
179	/*
180	* The current concurrency level. As it's likely to be accessed
181	* from other CPUs during try_to_wake_up(), put it in a separate
182	* cacheline.
183	*/
184	atomic_t nr_running ____cacheline_aligned_in_smp;
185
186	/*
187	* Destruction of pool is RCU protected to allow dereferences
188	* from get_work_pool().
189	*/
190	struct rcu_head rcu;
191	} ____cacheline_aligned_in_smp;
192
193	/*
194	* The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
195	* of work_struct->data are used for flags and the remaining high bits
196	* point to the pwq; thus, pwqs need to be aligned at two's power of the
197	* number of flag bits.
198	*/
199	struct pool_workqueue {
200	struct worker_pool pool; / I: the associated pool */
201	struct workqueue_struct wq; / I: the owning workqueue */
202	int work_color; /* L: current color */
203	int flush_color; /* L: flushing color */
204	int refcnt; /* L: reference count */
205	int nr_in_flight[WORK_NR_COLORS];
206	/* L: nr of in_flight works */
207	int nr_active; /* L: nr of active works */
208	int max_active; /* L: max active works */
209	struct list_head delayed_works; /* L: delayed works */
210	struct list_head pwqs_node; /* WR: node on wq->pwqs */
211	struct list_head mayday_node; /* MD: node on wq->maydays */
212
213	/*
214	* Release of unbound pwq is punted to system_wq. See put_pwq()
215	* and pwq_unbound_release_workfn() for details. pool_workqueue
216	* itself is also RCU protected so that the first pwq can be
217	* determined without grabbing wq->mutex.
218	*/
219	struct work_struct unbound_release_work;
220	struct rcu_head rcu;
221	} __aligned(1 << WORK_STRUCT_FLAG_BITS);
222
223	/*
224	* Structure used to wait for workqueue flush.
225	*/
226	struct wq_flusher {
227	struct list_head list; /* WQ: list of flushers */
228	int flush_color; /* WQ: flush color waiting for */
229	struct completion done; /* flush completion */
230	};
231
232	struct wq_device;
233
234	/*
235	* The externally visible workqueue. It relays the issued work items to
236	* the appropriate worker_pool through its pool_workqueues.
237	*/
238	struct workqueue_struct {
239	struct list_head pwqs; /* WR: all pwqs of this wq */
240	struct list_head list; /* PR: list of all workqueues */
241
242	struct mutex mutex; /* protects this wq */
243	int work_color; /* WQ: current work color */
244	int flush_color; /* WQ: current flush color */
245	atomic_t nr_pwqs_to_flush; /* flush in progress */
246	struct wq_flusher first_flusher; / WQ: first flusher */
247	struct list_head flusher_queue; /* WQ: flush waiters */
248	struct list_head flusher_overflow; /* WQ: flush overflow list */
249
250	struct list_head maydays; /* MD: pwqs requesting rescue */
251	struct worker rescuer; / I: rescue worker */
252
253	int nr_drainers; /* WQ: drain in progress */
254	int saved_max_active; /* WQ: saved pwq max_active */
255
256	struct workqueue_attrs unbound_attrs; / PW: only for unbound wqs */
257	struct pool_workqueue dfl_pwq; / PW: only for unbound wqs */
258
259	#ifdef CONFIG_SYSFS
260	struct wq_device wq_dev; / I: for sysfs interface */
261	#endif
262	#ifdef CONFIG_LOCKDEP
263	char *lock_name;
264	struct lock_class_key key;
265	struct lockdep_map lockdep_map;
266	#endif
267	char name[WQ_NAME_LEN]; /* I: workqueue name */
268
269	/*
270	* Destruction of workqueue_struct is RCU protected to allow walking
271	* the workqueues list without grabbing wq_pool_mutex.
272	* This is used to dump all workqueues from sysrq.
273	*/
274	struct rcu_head rcu;
275
276	/* hot fields used during command issue, aligned to cacheline */
277	unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */
278	struct pool_workqueue __percpu cpu_pwqs; / I: per-cpu pwqs */
279	struct pool_workqueue __rcu numa_pwq_tbl[]; / PWR: unbound pwqs indexed by node */
280	};
281
282	static struct kmem_cache *pwq_cache;
283
284	static cpumask_var_t *wq_numa_possible_cpumask;
285	/* possible CPUs of each node */
286
287	static bool wq_disable_numa;
288	module_param_named(disable_numa, wq_disable_numa, bool, 0444);
289
290	/* see the comment above the definition of WQ_POWER_EFFICIENT */
291	static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT);
292	module_param_named(power_efficient, wq_power_efficient, bool, 0444);
293
294	static bool wq_online; /* can kworkers be created yet? */
295
296	static bool wq_numa_enabled; /* unbound NUMA affinity enabled */
297
298	/* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
299	static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf;
300
301	static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */
302	static DEFINE_MUTEX(wq_pool_attach_mutex); /* protects worker attach/detach */
303	static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */
304	static DECLARE_WAIT_QUEUE_HEAD(wq_manager_wait); /* wait for manager to go away */
305
306	static LIST_HEAD(workqueues); /* PR: list of all workqueues */
307	static bool workqueue_freezing; /* PL: have wqs started freezing? */
308
309	/* PL: allowable cpus for unbound wqs and work items */
310	static cpumask_var_t wq_unbound_cpumask;
311
312	/* CPU where unbound work was last round robin scheduled from this CPU */
313	static DEFINE_PER_CPU(int, wq_rr_cpu_last);
314
315	/*
316	* Local execution of unbound work items is no longer guaranteed. The
317	* following always forces round-robin CPU selection on unbound work items
318	* to uncover usages which depend on it.
319	*/
320	#ifdef CONFIG_DEBUG_WQ_FORCE_RR_CPU
321	static bool wq_debug_force_rr_cpu = true;
322	#else
323	static bool wq_debug_force_rr_cpu = false;
324	#endif
325	module_param_named(debug_force_rr_cpu, wq_debug_force_rr_cpu, bool, 0644);
326
327	/* the per-cpu worker pools */
328	static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], cpu_worker_pools);
329
330	static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */
331
332	/* PL: hash of all unbound pools keyed by pool->attrs */
333	static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER);
334
335	/* I: attributes used when instantiating standard unbound pools on demand */
336	static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS];
337
338	/* I: attributes used when instantiating ordered pools on demand */
339	static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS];
340
341	struct workqueue_struct *system_wq __read_mostly;
342	EXPORT_SYMBOL(system_wq);
343	struct workqueue_struct *system_highpri_wq __read_mostly;
344	EXPORT_SYMBOL_GPL(system_highpri_wq);
345	struct workqueue_struct *system_long_wq __read_mostly;
346	EXPORT_SYMBOL_GPL(system_long_wq);
347	struct workqueue_struct *system_unbound_wq __read_mostly;
348	EXPORT_SYMBOL_GPL(system_unbound_wq);
349	struct workqueue_struct *system_freezable_wq __read_mostly;
350	EXPORT_SYMBOL_GPL(system_freezable_wq);
351	struct workqueue_struct *system_power_efficient_wq __read_mostly;
352	EXPORT_SYMBOL_GPL(system_power_efficient_wq);
353	struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly;
354	EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq);
355
356	static int worker_thread(void *__worker);
357	static void workqueue_sysfs_unregister(struct workqueue_struct *wq);
358
359	#define CREATE_TRACE_POINTS
360	#include <trace/events/workqueue.h>
361
362	#define assert_rcu_or_pool_mutex() \
363	RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
364	!lockdep_is_held(&wq_pool_mutex), \
365	"RCU or wq_pool_mutex should be held")
366
367	#define assert_rcu_or_wq_mutex(wq) \
368	RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
369	!lockdep_is_held(&wq->mutex), \
370	"RCU or wq->mutex should be held")
371
372	#define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \
373	RCU_LOCKDEP_WARN(!rcu_read_lock_held() && \
374	!lockdep_is_held(&wq->mutex) && \
375	!lockdep_is_held(&wq_pool_mutex), \
376	"RCU, wq->mutex or wq_pool_mutex should be held")
377
378	#define for_each_cpu_worker_pool(pool, cpu) \
379	for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
380	(pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
381	(pool)++)
382
383	/**
384	* for_each_pool - iterate through all worker_pools in the system
385	* @pool: iteration cursor
386	* @pi: integer used for iteration
387	*
388	* This must be called either with wq_pool_mutex held or RCU read
389	* locked. If the pool needs to be used beyond the locking in effect, the
390	* caller is responsible for guaranteeing that the pool stays online.
391	*
392	* The if/else clause exists only for the lockdep assertion and can be
393	* ignored.
394	*/
395	#define for_each_pool(pool, pi) \
396	idr_for_each_entry(&worker_pool_idr, pool, pi) \
397	if (({ assert_rcu_or_pool_mutex(); false; })) { } \
398	else
399
400	/**
401	* for_each_pool_worker - iterate through all workers of a worker_pool
402	* @worker: iteration cursor
403	* @pool: worker_pool to iterate workers of
404	*
405	* This must be called with wq_pool_attach_mutex.
406	*
407	* The if/else clause exists only for the lockdep assertion and can be
408	* ignored.
409	*/
410	#define for_each_pool_worker(worker, pool) \
411	list_for_each_entry((worker), &(pool)->workers, node) \
412	if (({ lockdep_assert_held(&wq_pool_attach_mutex); false; })) { } \
413	else
414
415	/**
416	* for_each_pwq - iterate through all pool_workqueues of the specified workqueue
417	* @pwq: iteration cursor
418	* @wq: the target workqueue
419	*
420	* This must be called either with wq->mutex held or RCU read locked.
421	* If the pwq needs to be used beyond the locking in effect, the caller is
422	* responsible for guaranteeing that the pwq stays online.
423	*
424	* The if/else clause exists only for the lockdep assertion and can be
425	* ignored.
426	*/
427	#define for_each_pwq(pwq, wq) \
428	list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
429	if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
430	else
431
432	#ifdef CONFIG_DEBUG_OBJECTS_WORK
433
434	static struct debug_obj_descr work_debug_descr;
435
436	static void work_debug_hint(void addr)
437	{
438	return ((struct work_struct *) addr)->func;
439	}
440
441	static bool work_is_static_object(void *addr)
442	{
443	struct work_struct *work = addr;
444
445	return test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work));
446	}
447
448	/*
449	* fixup_init is called when:
450	* - an active object is initialized
451	*/
452	static bool work_fixup_init(void *addr, enum debug_obj_state state)
453	{
454	struct work_struct *work = addr;
455
456	switch (state) {
457	case ODEBUG_STATE_ACTIVE:
458	cancel_work_sync(work);
459	debug_object_init(work, &work_debug_descr);
460	return true;
461	default:
462	return false;
463	}
464	}
465
466	/*
467	* fixup_free is called when:
468	* - an active object is freed
469	*/
470	static bool work_fixup_free(void *addr, enum debug_obj_state state)
471	{
472	struct work_struct *work = addr;
473
474	switch (state) {
475	case ODEBUG_STATE_ACTIVE:
476	cancel_work_sync(work);
477	debug_object_free(work, &work_debug_descr);
478	return true;
479	default:
480	return false;
481	}
482	}
483
484	static struct debug_obj_descr work_debug_descr = {
485	.name = "work_struct",
486	.debug_hint = work_debug_hint,
487	.is_static_object = work_is_static_object,
488	.fixup_init = work_fixup_init,
489	.fixup_free = work_fixup_free,
490	};
491
492	static inline void debug_work_activate(struct work_struct *work)
493	{
494	debug_object_activate(work, &work_debug_descr);
495	}
496
497	static inline void debug_work_deactivate(struct work_struct *work)
498	{
499	debug_object_deactivate(work, &work_debug_descr);
500	}
501
502	void __init_work(struct work_struct *work, int onstack)
503	{
504	if (onstack)
505	debug_object_init_on_stack(work, &work_debug_descr);
506	else
507	debug_object_init(work, &work_debug_descr);
508	}
509	EXPORT_SYMBOL_GPL(__init_work);
510
511	void destroy_work_on_stack(struct work_struct *work)
512	{
513	debug_object_free(work, &work_debug_descr);
514	}
515	EXPORT_SYMBOL_GPL(destroy_work_on_stack);
516
517	void destroy_delayed_work_on_stack(struct delayed_work *work)
518	{
519	destroy_timer_on_stack(&work->timer);
520	debug_object_free(&work->work, &work_debug_descr);
521	}
522	EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack);
523
524	#else
525	static inline void debug_work_activate(struct work_struct *work) { }
526	static inline void debug_work_deactivate(struct work_struct *work) { }
527	#endif
528
529	/**
530	* worker_pool_assign_id - allocate ID and assing it to @pool
531	* @pool: the pool pointer of interest
532	*
533	* Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned
534	* successfully, -errno on failure.
535	*/
536	static int worker_pool_assign_id(struct worker_pool *pool)
537	{
538	int ret;
539
540	lockdep_assert_held(&wq_pool_mutex);
541
542	ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE,
543	GFP_KERNEL);
544	if (ret >= 0) {
545	pool->id = ret;
546	return 0;
547	}
548	return ret;
549	}
550
551	/**
552	* unbound_pwq_by_node - return the unbound pool_workqueue for the given node
553	* @wq: the target workqueue
554	* @node: the node ID
555	*
556	* This must be called with any of wq_pool_mutex, wq->mutex or RCU
557	* read locked.
558	* If the pwq needs to be used beyond the locking in effect, the caller is
559	* responsible for guaranteeing that the pwq stays online.
560	*
561	* Return: The unbound pool_workqueue for @node.
562	*/
563	static struct pool_workqueue unbound_pwq_by_node(struct workqueue_struct wq,
564	int node)
565	{
566	assert_rcu_or_wq_mutex_or_pool_mutex(wq);
567
568	/*
569	* XXX: @node can be NUMA_NO_NODE if CPU goes offline while a
570	* delayed item is pending. The plan is to keep CPU -> NODE
571	* mapping valid and stable across CPU on/offlines. Once that
572	* happens, this workaround can be removed.
573	*/
574	if (unlikely(node == NUMA_NO_NODE))
575	return wq->dfl_pwq;
576
577	return rcu_dereference_raw(wq->numa_pwq_tbl[node]);
578	}
579
580	static unsigned int work_color_to_flags(int color)
581	{
582	return color << WORK_STRUCT_COLOR_SHIFT;
583	}
584
585	static int get_work_color(struct work_struct *work)
586	{
587	return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) &
588	((1 << WORK_STRUCT_COLOR_BITS) - 1);
589	}
590
591	static int work_next_color(int color)
592	{
593	return (color + 1) % WORK_NR_COLORS;
594	}
595
596	/*
597	* While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
598	* contain the pointer to the queued pwq. Once execution starts, the flag
599	* is cleared and the high bits contain OFFQ flags and pool ID.
600	*
601	* set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
602	* and clear_work_data() can be used to set the pwq, pool or clear
603	* work->data. These functions should only be called while the work is
604	* owned - ie. while the PENDING bit is set.
605	*
606	* get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
607	* corresponding to a work. Pool is available once the work has been
608	* queued anywhere after initialization until it is sync canceled. pwq is
609	* available only while the work item is queued.
610	*
611	* %WORK_OFFQ_CANCELING is used to mark a work item which is being
612	* canceled. While being canceled, a work item may have its PENDING set
613	* but stay off timer and worklist for arbitrarily long and nobody should
614	* try to steal the PENDING bit.
615	*/
616	static inline void set_work_data(struct work_struct *work, unsigned long data,
617	unsigned long flags)
618	{
619	WARN_ON_ONCE(!work_pending(work));
620	atomic_long_set(&work->data, data \| flags \| work_static(work));
621	}
622
623	static void set_work_pwq(struct work_struct work, struct pool_workqueue pwq,
624	unsigned long extra_flags)
625	{
626	set_work_data(work, (unsigned long)pwq,
627	WORK_STRUCT_PENDING \| WORK_STRUCT_PWQ \| extra_flags);
628	}
629
630	static void set_work_pool_and_keep_pending(struct work_struct *work,
631	int pool_id)
632	{
633	set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT,
634	WORK_STRUCT_PENDING);
635	}
636
637	static void set_work_pool_and_clear_pending(struct work_struct *work,
638	int pool_id)
639	{
640	/*
641	* The following wmb is paired with the implied mb in
642	* test_and_set_bit(PENDING) and ensures all updates to @work made
643	* here are visible to and precede any updates by the next PENDING
644	* owner.
645	*/
646	smp_wmb();
647	set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0);
648	/*
649	* The following mb guarantees that previous clear of a PENDING bit
650	* will not be reordered with any speculative LOADS or STORES from
651	* work->current_func, which is executed afterwards. This possible
652	* reordering can lead to a missed execution on attempt to queue
653	* the same @work. E.g. consider this case:
654	*
655	* CPU#0 CPU#1
656	* ---------------------------- --------------------------------
657	*
658	* 1 STORE event_indicated
659	* 2 queue_work_on() {
660	* 3 test_and_set_bit(PENDING)
661	* 4 } set_..._and_clear_pending() {
662	* 5 set_work_data() # clear bit
663	* 6 smp_mb()
664	* 7 work->current_func() {
665	* 8 LOAD event_indicated
666	* }
667	*
668	* Without an explicit full barrier speculative LOAD on line 8 can
669	* be executed before CPU#0 does STORE on line 1. If that happens,
670	* CPU#0 observes the PENDING bit is still set and new execution of
671	* a @work is not queued in a hope, that CPU#1 will eventually
672	* finish the queued @work. Meanwhile CPU#1 does not see
673	* event_indicated is set, because speculative LOAD was executed
674	* before actual STORE.
675	*/
676	smp_mb();
677	}
678
679	static void clear_work_data(struct work_struct *work)
680	{
681	smp_wmb(); /* see set_work_pool_and_clear_pending() */
682	set_work_data(work, WORK_STRUCT_NO_POOL, 0);
683	}
684
685	static struct pool_workqueue get_work_pwq(struct work_struct work)
686	{
687	unsigned long data = atomic_long_read(&work->data);
688
689	if (data & WORK_STRUCT_PWQ)
690	return (void *)(data & WORK_STRUCT_WQ_DATA_MASK);
691	else
692	return NULL;
693	}
694
695	/**
696	* get_work_pool - return the worker_pool a given work was associated with
697	* @work: the work item of interest
698	*
699	* Pools are created and destroyed under wq_pool_mutex, and allows read
700	* access under RCU read lock. As such, this function should be
701	* called under wq_pool_mutex or inside of a rcu_read_lock() region.
702	*
703	* All fields of the returned pool are accessible as long as the above
704	* mentioned locking is in effect. If the returned pool needs to be used
705	* beyond the critical section, the caller is responsible for ensuring the
706	* returned pool is and stays online.
707	*
708	* Return: The worker_pool @work was last associated with. %NULL if none.
709	*/
710	static struct worker_pool get_work_pool(struct work_struct work)
711	{
712	unsigned long data = atomic_long_read(&work->data);
713	int pool_id;
714
715	assert_rcu_or_pool_mutex();
716
717	if (data & WORK_STRUCT_PWQ)
718	return ((struct pool_workqueue *)
719	(data & WORK_STRUCT_WQ_DATA_MASK))->pool;
720
721	pool_id = data >> WORK_OFFQ_POOL_SHIFT;
722	if (pool_id == WORK_OFFQ_POOL_NONE)
723	return NULL;
724
725	return idr_find(&worker_pool_idr, pool_id);
726	}
727
728	/**
729	* get_work_pool_id - return the worker pool ID a given work is associated with
730	* @work: the work item of interest
731	*
732	* Return: The worker_pool ID @work was last associated with.
733	* %WORK_OFFQ_POOL_NONE if none.
734	*/
735	static int get_work_pool_id(struct work_struct *work)
736	{
737	unsigned long data = atomic_long_read(&work->data);
738
739	if (data & WORK_STRUCT_PWQ)
740	return ((struct pool_workqueue *)
741	(data & WORK_STRUCT_WQ_DATA_MASK))->pool->id;
742
743	return data >> WORK_OFFQ_POOL_SHIFT;
744	}
745
746	static void mark_work_canceling(struct work_struct *work)
747	{
748	unsigned long pool_id = get_work_pool_id(work);
749
750	pool_id <<= WORK_OFFQ_POOL_SHIFT;
751	set_work_data(work, pool_id \| WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING);
752	}
753
754	static bool work_is_canceling(struct work_struct *work)
755	{
756	unsigned long data = atomic_long_read(&work->data);
757
758	return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING);
759	}
760
761	/*
762	* Policy functions. These define the policies on how the global worker
763	* pools are managed. Unless noted otherwise, these functions assume that
764	* they're being called with pool->lock held.
765	*/
766
767	static bool __need_more_worker(struct worker_pool *pool)
768	{
769	return !atomic_read(&pool->nr_running);
770	}
771
772	/*
773	* Need to wake up a worker? Called from anything but currently
774	* running workers.
775	*
776	* Note that, because unbound workers never contribute to nr_running, this
777	* function will always return %true for unbound pools as long as the
778	* worklist isn't empty.
779	*/
780	static bool need_more_worker(struct worker_pool *pool)
781	{
782	return !list_empty(&pool->worklist) && __need_more_worker(pool);
783	}
784
785	/* Can I start working? Called from busy but !running workers. */
786	static bool may_start_working(struct worker_pool *pool)
787	{
788	return pool->nr_idle;
789	}
790
791	/* Do I need to keep working? Called from currently running workers. */
792	static bool keep_working(struct worker_pool *pool)
793	{
794	return !list_empty(&pool->worklist) &&
795	atomic_read(&pool->nr_running) <= 1;
796	}
797
798	/* Do we need a new worker? Called from manager. */
799	static bool need_to_create_worker(struct worker_pool *pool)
800	{
801	return need_more_worker(pool) && !may_start_working(pool);
802	}
803
804	/* Do we have too many workers and should some go away? */
805	static bool too_many_workers(struct worker_pool *pool)
806	{
807	bool managing = pool->flags & POOL_MANAGER_ACTIVE;
808	int nr_idle = pool->nr_idle + managing; /* manager is considered idle */
809	int nr_busy = pool->nr_workers - nr_idle;
810
811	return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy;
812	}
813
814	/*
815	* Wake up functions.
816	*/
817
818	/* Return the first idle worker. Safe with preemption disabled */
819	static struct worker first_idle_worker(struct worker_pool pool)
820	{
821	if (unlikely(list_empty(&pool->idle_list)))
822	return NULL;
823
824	return list_first_entry(&pool->idle_list, struct worker, entry);
825	}
826
827	/**
828	* wake_up_worker - wake up an idle worker
829	* @pool: worker pool to wake worker from
830	*
831	* Wake up the first idle worker of @pool.
832	*
833	* CONTEXT:
834	* spin_lock_irq(pool->lock).
835	*/
836	static void wake_up_worker(struct worker_pool *pool)
837	{
838	struct worker *worker = first_idle_worker(pool);
839
840	if (likely(worker))
841	wake_up_process(worker->task);
842	}
843
844	/**
845	* wq_worker_running - a worker is running again
846	* @task: task waking up
847	*
848	* This function is called when a worker returns from schedule()
849	*/
850	void wq_worker_running(struct task_struct *task)
851	{
852	struct worker *worker = kthread_data(task);
853
854	if (!worker->sleeping)
855	return;
856	if (!(worker->flags & WORKER_NOT_RUNNING))
857	atomic_inc(&worker->pool->nr_running);
858	worker->sleeping = 0;
859	}
860
861	/**
862	* wq_worker_sleeping - a worker is going to sleep
863	* @task: task going to sleep
864	*
865	* This function is called from schedule() when a busy worker is
866	* going to sleep.
867	*/
868	void wq_worker_sleeping(struct task_struct *task)
869	{
870	struct worker next, worker = kthread_data(task);
871	struct worker_pool *pool;
872
873	/*
874	* Rescuers, which may not have all the fields set up like normal
875	* workers, also reach here, let's not access anything before
876	* checking NOT_RUNNING.
877	*/
878	if (worker->flags & WORKER_NOT_RUNNING)
879	return;
880
881	pool = worker->pool;
882
883	if (WARN_ON_ONCE(worker->sleeping))
884	return;
885
886	worker->sleeping = 1;
887	spin_lock_irq(&pool->lock);
888
889	/*
890	* The counterpart of the following dec_and_test, implied mb,
891	* worklist not empty test sequence is in insert_work().
892	* Please read comment there.
893	*
894	* NOT_RUNNING is clear. This means that we're bound to and
895	* running on the local cpu w/ rq lock held and preemption
896	* disabled, which in turn means that none else could be
897	* manipulating idle_list, so dereferencing idle_list without pool
898	* lock is safe.
899	*/
900	if (atomic_dec_and_test(&pool->nr_running) &&
901	!list_empty(&pool->worklist)) {
902	next = first_idle_worker(pool);
903	if (next)
904	wake_up_process(next->task);
905	}
906	spin_unlock_irq(&pool->lock);
907	}
908
909	/**
910	* wq_worker_last_func - retrieve worker's last work function
911	* @task: Task to retrieve last work function of.
912	*
913	* Determine the last function a worker executed. This is called from
914	* the scheduler to get a worker's last known identity.
915	*
916	* CONTEXT:
917	* spin_lock_irq(rq->lock)
918	*
919	* This function is called during schedule() when a kworker is going
920	* to sleep. It's used by psi to identify aggregation workers during
921	* dequeuing, to allow periodic aggregation to shut-off when that
922	* worker is the last task in the system or cgroup to go to sleep.
923	*
924	* As this function doesn't involve any workqueue-related locking, it
925	* only returns stable values when called from inside the scheduler's
926	* queuing and dequeuing paths, when @task, which must be a kworker,
927	* is guaranteed to not be processing any works.
928	*
929	* Return:
930	* The last work function %current executed as a worker, NULL if it
931	* hasn't executed any work yet.
932	*/
933	work_func_t wq_worker_last_func(struct task_struct *task)
934	{
935	struct worker *worker = kthread_data(task);
936
937	return worker->last_func;
938	}
939
940	/**
941	* worker_set_flags - set worker flags and adjust nr_running accordingly
942	* @worker: self
943	* @flags: flags to set
944	*
945	* Set @flags in @worker->flags and adjust nr_running accordingly.
946	*
947	* CONTEXT:
948	* spin_lock_irq(pool->lock)
949	*/
950	static inline void worker_set_flags(struct worker *worker, unsigned int flags)
951	{
952	struct worker_pool *pool = worker->pool;
953
954	WARN_ON_ONCE(worker->task != current);
955
956	/* If transitioning into NOT_RUNNING, adjust nr_running. */
957	if ((flags & WORKER_NOT_RUNNING) &&
958	!(worker->flags & WORKER_NOT_RUNNING)) {
959	atomic_dec(&pool->nr_running);
960	}
961
962	worker->flags \|= flags;
963	}
964
965	/**
966	* worker_clr_flags - clear worker flags and adjust nr_running accordingly
967	* @worker: self
968	* @flags: flags to clear
969	*
970	* Clear @flags in @worker->flags and adjust nr_running accordingly.
971	*
972	* CONTEXT:
973	* spin_lock_irq(pool->lock)
974	*/
975	static inline void worker_clr_flags(struct worker *worker, unsigned int flags)
976	{
977	struct worker_pool *pool = worker->pool;
978	unsigned int oflags = worker->flags;
979
980	WARN_ON_ONCE(worker->task != current);
981
982	worker->flags &= ~flags;
983
984	/*
985	* If transitioning out of NOT_RUNNING, increment nr_running. Note
986	* that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
987	* of multiple flags, not a single flag.
988	*/
989	if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING))
990	if (!(worker->flags & WORKER_NOT_RUNNING))
991	atomic_inc(&pool->nr_running);
992	}
993
994	/**
995	* find_worker_executing_work - find worker which is executing a work
996	* @pool: pool of interest
997	* @work: work to find worker for
998	*
999	* Find a worker which is executing @work on @pool by searching
1000	* @pool->busy_hash which is keyed by the address of @work. For a worker
1001	* to match, its current execution should match the address of @work and
1002	* its work function. This is to avoid unwanted dependency between
1003	* unrelated work executions through a work item being recycled while still
1004	* being executed.
1005	*
1006	* This is a bit tricky. A work item may be freed once its execution
1007	* starts and nothing prevents the freed area from being recycled for
1008	* another work item. If the same work item address ends up being reused
1009	* before the original execution finishes, workqueue will identify the
1010	* recycled work item as currently executing and make it wait until the
1011	* current execution finishes, introducing an unwanted dependency.
1012	*
1013	* This function checks the work item address and work function to avoid
1014	* false positives. Note that this isn't complete as one may construct a
1015	* work function which can introduce dependency onto itself through a
1016	* recycled work item. Well, if somebody wants to shoot oneself in the
1017	* foot that badly, there's only so much we can do, and if such deadlock
1018	* actually occurs, it should be easy to locate the culprit work function.
1019	*
1020	* CONTEXT:
1021	* spin_lock_irq(pool->lock).
1022	*
1023	* Return:
1024	* Pointer to worker which is executing @work if found, %NULL
1025	* otherwise.
1026	*/
1027	static struct worker find_worker_executing_work(struct worker_pool pool,
1028	struct work_struct *work)
1029	{
1030	struct worker *worker;
1031
1032	hash_for_each_possible(pool->busy_hash, worker, hentry,
1033	(unsigned long)work)
1034	if (worker->current_work == work &&
1035	worker->current_func == work->func)
1036	return worker;
1037
1038	return NULL;
1039	}
1040
1041	/**
1042	* move_linked_works - move linked works to a list
1043	* @work: start of series of works to be scheduled
1044	* @head: target list to append @work to
1045	* @nextp: out parameter for nested worklist walking
1046	*
1047	* Schedule linked works starting from @work to @head. Work series to
1048	* be scheduled starts at @work and includes any consecutive work with
1049	* WORK_STRUCT_LINKED set in its predecessor.
1050	*
1051	* If @nextp is not NULL, it's updated to point to the next work of
1052	* the last scheduled work. This allows move_linked_works() to be
1053	* nested inside outer list_for_each_entry_safe().
1054	*
1055	* CONTEXT:
1056	* spin_lock_irq(pool->lock).
1057	*/
1058	static void move_linked_works(struct work_struct work, struct list_head head,
1059	struct work_struct **nextp)
1060	{
1061	struct work_struct *n;
1062
1063	/*
1064	* Linked worklist will always end before the end of the list,
1065	* use NULL for list head.
1066	*/
1067	list_for_each_entry_safe_from(work, n, NULL, entry) {
1068	list_move_tail(&work->entry, head);
1069	if (!(*work_data_bits(work) & WORK_STRUCT_LINKED))
1070	break;
1071	}
1072
1073	/*
1074	* If we're already inside safe list traversal and have moved
1075	* multiple works to the scheduled queue, the next position
1076	* needs to be updated.
1077	*/
1078	if (nextp)
1079	*nextp = n;
1080	}
1081
1082	/**
1083	* get_pwq - get an extra reference on the specified pool_workqueue
1084	* @pwq: pool_workqueue to get
1085	*
1086	* Obtain an extra reference on @pwq. The caller should guarantee that
1087	* @pwq has positive refcnt and be holding the matching pool->lock.
1088	*/
1089	static void get_pwq(struct pool_workqueue *pwq)
1090	{
1091	lockdep_assert_held(&pwq->pool->lock);
1092	WARN_ON_ONCE(pwq->refcnt <= 0);
1093	pwq->refcnt++;
1094	}
1095
1096	/**
1097	* put_pwq - put a pool_workqueue reference
1098	* @pwq: pool_workqueue to put
1099	*
1100	* Drop a reference of @pwq. If its refcnt reaches zero, schedule its
1101	* destruction. The caller should be holding the matching pool->lock.
1102	*/
1103	static void put_pwq(struct pool_workqueue *pwq)
1104	{
1105	lockdep_assert_held(&pwq->pool->lock);
1106	if (likely(--pwq->refcnt))
1107	return;
1108	if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND)))
1109	return;
1110	/*
1111	* @pwq can't be released under pool->lock, bounce to
1112	* pwq_unbound_release_workfn(). This never recurses on the same
1113	* pool->lock as this path is taken only for unbound workqueues and
1114	* the release work item is scheduled on a per-cpu workqueue. To
1115	* avoid lockdep warning, unbound pool->locks are given lockdep
1116	* subclass of 1 in get_unbound_pool().
1117	*/
1118	schedule_work(&pwq->unbound_release_work);
1119	}
1120
1121	/**
1122	* put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
1123	* @pwq: pool_workqueue to put (can be %NULL)
1124	*
1125	* put_pwq() with locking. This function also allows %NULL @pwq.
1126	*/
1127	static void put_pwq_unlocked(struct pool_workqueue *pwq)
1128	{
1129	if (pwq) {
1130	/*
1131	* As both pwqs and pools are RCU protected, the
1132	* following lock operations are safe.
1133	*/
1134	spin_lock_irq(&pwq->pool->lock);
1135	put_pwq(pwq);
1136	spin_unlock_irq(&pwq->pool->lock);
1137	}
1138	}
1139
1140	static void pwq_activate_delayed_work(struct work_struct *work)
1141	{
1142	struct pool_workqueue *pwq = get_work_pwq(work);
1143
1144	trace_workqueue_activate_work(work);
1145	if (list_empty(&pwq->pool->worklist))
1146	pwq->pool->watchdog_ts = jiffies;
1147	move_linked_works(work, &pwq->pool->worklist, NULL);
1148	__clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work));
1149	pwq->nr_active++;
1150	}
1151
1152	static void pwq_activate_first_delayed(struct pool_workqueue *pwq)
1153	{
1154	struct work_struct *work = list_first_entry(&pwq->delayed_works,
1155	struct work_struct, entry);
1156
1157	pwq_activate_delayed_work(work);
1158	}
1159
1160	/**
1161	* pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
1162	* @pwq: pwq of interest
1163	* @color: color of work which left the queue
1164	*
1165	* A work either has completed or is removed from pending queue,
1166	* decrement nr_in_flight of its pwq and handle workqueue flushing.
1167	*
1168	* CONTEXT:
1169	* spin_lock_irq(pool->lock).
1170	*/
1171	static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color)
1172	{
1173	/* uncolored work items don't participate in flushing or nr_active */
1174	if (color == WORK_NO_COLOR)
1175	goto out_put;
1176
1177	pwq->nr_in_flight[color]--;
1178
1179	pwq->nr_active--;
1180	if (!list_empty(&pwq->delayed_works)) {
1181	/* one down, submit a delayed one */
1182	if (pwq->nr_active < pwq->max_active)
1183	pwq_activate_first_delayed(pwq);
1184	}
1185
1186	/* is flush in progress and are we at the flushing tip? */
1187	if (likely(pwq->flush_color != color))
1188	goto out_put;
1189
1190	/* are there still in-flight works? */
1191	if (pwq->nr_in_flight[color])
1192	goto out_put;
1193
1194	/* this pwq is done, clear flush_color */
1195	pwq->flush_color = -1;
1196
1197	/*
1198	* If this was the last pwq, wake up the first flusher. It
1199	* will handle the rest.
1200	*/
1201	if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush))
1202	complete(&pwq->wq->first_flusher->done);
1203	out_put:
1204	put_pwq(pwq);
1205	}
1206
1207	/**
1208	* try_to_grab_pending - steal work item from worklist and disable irq
1209	* @work: work item to steal
1210	* @is_dwork: @work is a delayed_work
1211	* @flags: place to store irq state
1212	*
1213	* Try to grab PENDING bit of @work. This function can handle @work in any
1214	* stable state - idle, on timer or on worklist.
1215	*
1216	* Return:
1217	* 1 if @work was pending and we successfully stole PENDING
1218	* 0 if @work was idle and we claimed PENDING
1219	* -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
1220	* -ENOENT if someone else is canceling @work, this state may persist
1221	* for arbitrarily long
1222	*
1223	* Note:
1224	* On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
1225	* interrupted while holding PENDING and @work off queue, irq must be
1226	* disabled on entry. This, combined with delayed_work->timer being
1227	* irqsafe, ensures that we return -EAGAIN for finite short period of time.
1228	*
1229	* On successful return, >= 0, irq is disabled and the caller is
1230	* responsible for releasing it using local_irq_restore(*@flags).
1231	*
1232	* This function is safe to call from any context including IRQ handler.
1233	*/
1234	static int try_to_grab_pending(struct work_struct *work, bool is_dwork,
1235	unsigned long *flags)
1236	{
1237	struct worker_pool *pool;
1238	struct pool_workqueue *pwq;
1239
1240	local_irq_save(*flags);
1241
1242	/* try to steal the timer if it exists */
1243	if (is_dwork) {
1244	struct delayed_work *dwork = to_delayed_work(work);
1245
1246	/*
1247	* dwork->timer is irqsafe. If del_timer() fails, it's
1248	* guaranteed that the timer is not queued anywhere and not
1249	* running on the local CPU.
1250	*/
1251	if (likely(del_timer(&dwork->timer)))
1252	return 1;
1253	}
1254
1255	/* try to claim PENDING the normal way */
1256	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work)))
1257	return 0;
1258
1259	rcu_read_lock();
1260	/*
1261	* The queueing is in progress, or it is already queued. Try to
1262	* steal it from ->worklist without clearing WORK_STRUCT_PENDING.
1263	*/
1264	pool = get_work_pool(work);
1265	if (!pool)
1266	goto fail;
1267
1268	spin_lock(&pool->lock);
1269	/*
1270	* work->data is guaranteed to point to pwq only while the work
1271	* item is queued on pwq->wq, and both updating work->data to point
1272	* to pwq on queueing and to pool on dequeueing are done under
1273	* pwq->pool->lock. This in turn guarantees that, if work->data
1274	* points to pwq which is associated with a locked pool, the work
1275	* item is currently queued on that pool.
1276	*/
1277	pwq = get_work_pwq(work);
1278	if (pwq && pwq->pool == pool) {
1279	debug_work_deactivate(work);
1280
1281	/*
1282	* A delayed work item cannot be grabbed directly because
1283	* it might have linked NO_COLOR work items which, if left
1284	* on the delayed_list, will confuse pwq->nr_active
1285	* management later on and cause stall. Make sure the work
1286	* item is activated before grabbing.
1287	*/
1288	if (*work_data_bits(work) & WORK_STRUCT_DELAYED)
1289	pwq_activate_delayed_work(work);
1290
1291	list_del_init(&work->entry);
1292	pwq_dec_nr_in_flight(pwq, get_work_color(work));
1293
1294	/* work->data points to pwq iff queued, point to pool */
1295	set_work_pool_and_keep_pending(work, pool->id);
1296
1297	spin_unlock(&pool->lock);
1298	rcu_read_unlock();
1299	return 1;
1300	}
1301	spin_unlock(&pool->lock);
1302	fail:
1303	rcu_read_unlock();
1304	local_irq_restore(*flags);
1305	if (work_is_canceling(work))
1306	return -ENOENT;
1307	cpu_relax();
1308	return -EAGAIN;
1309	}
1310
1311	/**
1312	* insert_work - insert a work into a pool
1313	* @pwq: pwq @work belongs to
1314	* @work: work to insert
1315	* @head: insertion point
1316	* @extra_flags: extra WORK_STRUCT_* flags to set
1317	*
1318	* Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
1319	* work_struct flags.
1320	*
1321	* CONTEXT:
1322	* spin_lock_irq(pool->lock).
1323	*/
1324	static void insert_work(struct pool_workqueue pwq, struct work_struct work,
1325	struct list_head *head, unsigned int extra_flags)
1326	{
1327	struct worker_pool *pool = pwq->pool;
1328
1329	/* we own @work, set data and link */
1330	set_work_pwq(work, pwq, extra_flags);
1331	list_add_tail(&work->entry, head);
1332	get_pwq(pwq);
1333
1334	/*
1335	* Ensure either wq_worker_sleeping() sees the above
1336	* list_add_tail() or we see zero nr_running to avoid workers lying
1337	* around lazily while there are works to be processed.
1338	*/
1339	smp_mb();
1340
1341	if (__need_more_worker(pool))
1342	wake_up_worker(pool);
1343	}
1344
1345	/*
1346	* Test whether @work is being queued from another work executing on the
1347	* same workqueue.
1348	*/
1349	static bool is_chained_work(struct workqueue_struct *wq)
1350	{
1351	struct worker *worker;
1352
1353	worker = current_wq_worker();
1354	/*
1355	* Return %true iff I'm a worker executing a work item on @wq. If
1356	* I'm @worker, it's safe to dereference it without locking.
1357	*/
1358	return worker && worker->current_pwq->wq == wq;
1359	}
1360
1361	/*
1362	* When queueing an unbound work item to a wq, prefer local CPU if allowed
1363	* by wq_unbound_cpumask. Otherwise, round robin among the allowed ones to
1364	* avoid perturbing sensitive tasks.
1365	*/
1366	static int wq_select_unbound_cpu(int cpu)
1367	{
1368	static bool printed_dbg_warning;
1369	int new_cpu;
1370
1371	if (likely(!wq_debug_force_rr_cpu)) {
1372	if (cpumask_test_cpu(cpu, wq_unbound_cpumask))
1373	return cpu;
1374	} else if (!printed_dbg_warning) {
1375	pr_warn("workqueue: round-robin CPU selection forced, expect performance impact\n");
1376	printed_dbg_warning = true;
1377	}
1378
1379	if (cpumask_empty(wq_unbound_cpumask))
1380	return cpu;
1381
1382	new_cpu = __this_cpu_read(wq_rr_cpu_last);
1383	new_cpu = cpumask_next_and(new_cpu, wq_unbound_cpumask, cpu_online_mask);
1384	if (unlikely(new_cpu >= nr_cpu_ids)) {
1385	new_cpu = cpumask_first_and(wq_unbound_cpumask, cpu_online_mask);
1386	if (unlikely(new_cpu >= nr_cpu_ids))
1387	return cpu;
1388	}
1389	__this_cpu_write(wq_rr_cpu_last, new_cpu);
1390
1391	return new_cpu;
1392	}
1393
1394	static void __queue_work(int cpu, struct workqueue_struct *wq,
1395	struct work_struct *work)
1396	{
1397	struct pool_workqueue *pwq;
1398	struct worker_pool *last_pool;
1399	struct list_head *worklist;
1400	unsigned int work_flags;
1401	unsigned int req_cpu = cpu;
1402
1403	/*
1404	* While a work item is PENDING && off queue, a task trying to
1405	* steal the PENDING will busy-loop waiting for it to either get
1406	* queued or lose PENDING. Grabbing PENDING and queueing should
1407	* happen with IRQ disabled.
1408	*/
1409	lockdep_assert_irqs_disabled();
1410
1411	debug_work_activate(work);
1412
1413	/* if draining, only works from the same workqueue are allowed */
1414	if (unlikely(wq->flags & __WQ_DRAINING) &&
1415	WARN_ON_ONCE(!is_chained_work(wq)))
1416	return;
1417	rcu_read_lock();
1418	retry:
1419	if (req_cpu == WORK_CPU_UNBOUND)
1420	cpu = wq_select_unbound_cpu(raw_smp_processor_id());
1421
1422	/* pwq which will be used unless @work is executing elsewhere */
1423	if (!(wq->flags & WQ_UNBOUND))
1424	pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
1425	else
1426	pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
1427
1428	/*
1429	* If @work was previously on a different pool, it might still be
1430	* running there, in which case the work needs to be queued on that
1431	* pool to guarantee non-reentrancy.
1432	*/
1433	last_pool = get_work_pool(work);
1434	if (last_pool && last_pool != pwq->pool) {
1435	struct worker *worker;
1436
1437	spin_lock(&last_pool->lock);
1438
1439	worker = find_worker_executing_work(last_pool, work);
1440
1441	if (worker && worker->current_pwq->wq == wq) {
1442	pwq = worker->current_pwq;
1443	} else {
1444	/* meh... not running there, queue here */
1445	spin_unlock(&last_pool->lock);
1446	spin_lock(&pwq->pool->lock);
1447	}
1448	} else {
1449	spin_lock(&pwq->pool->lock);
1450	}
1451
1452	/*
1453	* pwq is determined and locked. For unbound pools, we could have
1454	* raced with pwq release and it could already be dead. If its
1455	* refcnt is zero, repeat pwq selection. Note that pwqs never die
1456	* without another pwq replacing it in the numa_pwq_tbl or while
1457	* work items are executing on it, so the retrying is guaranteed to
1458	* make forward-progress.
1459	*/
1460	if (unlikely(!pwq->refcnt)) {
1461	if (wq->flags & WQ_UNBOUND) {
1462	spin_unlock(&pwq->pool->lock);
1463	cpu_relax();
1464	goto retry;
1465	}
1466	/* oops */
1467	WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
1468	wq->name, cpu);
1469	}
1470
1471	/* pwq determined, queue */
1472	trace_workqueue_queue_work(req_cpu, pwq, work);
1473
1474	if (WARN_ON(!list_empty(&work->entry)))
1475	goto out;
1476
1477	pwq->nr_in_flight[pwq->work_color]++;
1478	work_flags = work_color_to_flags(pwq->work_color);
1479
1480	if (likely(pwq->nr_active < pwq->max_active)) {
1481	trace_workqueue_activate_work(work);
1482	pwq->nr_active++;
1483	worklist = &pwq->pool->worklist;
1484	if (list_empty(worklist))
1485	pwq->pool->watchdog_ts = jiffies;
1486	} else {
1487	work_flags \|= WORK_STRUCT_DELAYED;
1488	worklist = &pwq->delayed_works;
1489	}
1490
1491	insert_work(pwq, work, worklist, work_flags);
1492
1493	out:
1494	spin_unlock(&pwq->pool->lock);
1495	rcu_read_unlock();
1496	}
1497
1498	/**
1499	* queue_work_on - queue work on specific cpu
1500	* @cpu: CPU number to execute work on
1501	* @wq: workqueue to use
1502	* @work: work to queue
1503	*
1504	* We queue the work to a specific CPU, the caller must ensure it
1505	* can't go away.
1506	*
1507	* Return: %false if @work was already on a queue, %true otherwise.
1508	*/
1509	bool queue_work_on(int cpu, struct workqueue_struct *wq,
1510	struct work_struct *work)
1511	{
1512	bool ret = false;
1513	unsigned long flags;
1514
1515	local_irq_save(flags);
1516
1517	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1518	__queue_work(cpu, wq, work);
1519	ret = true;
1520	}
1521
1522	local_irq_restore(flags);
1523	return ret;
1524	}
1525	EXPORT_SYMBOL(queue_work_on);
1526
1527	/**
1528	* workqueue_select_cpu_near - Select a CPU based on NUMA node
1529	* @node: NUMA node ID that we want to select a CPU from
1530	*
1531	* This function will attempt to find a "random" cpu available on a given
1532	* node. If there are no CPUs available on the given node it will return
1533	* WORK_CPU_UNBOUND indicating that we should just schedule to any
1534	* available CPU if we need to schedule this work.
1535	*/
1536	static int workqueue_select_cpu_near(int node)
1537	{
1538	int cpu;
1539
1540	/* No point in doing this if NUMA isn't enabled for workqueues */
1541	if (!wq_numa_enabled)
1542	return WORK_CPU_UNBOUND;
1543
1544	/* Delay binding to CPU if node is not valid or online */
1545	if (node < 0 \|\| node >= MAX_NUMNODES \|\| !node_online(node))
1546	return WORK_CPU_UNBOUND;
1547
1548	/* Use local node/cpu if we are already there */
1549	cpu = raw_smp_processor_id();
1550	if (node == cpu_to_node(cpu))
1551	return cpu;
1552
1553	/* Use "random" otherwise know as "first" online CPU of node */
1554	cpu = cpumask_any_and(cpumask_of_node(node), cpu_online_mask);
1555
1556	/* If CPU is valid return that, otherwise just defer */
1557	return cpu < nr_cpu_ids ? cpu : WORK_CPU_UNBOUND;
1558	}
1559
1560	/**
1561	* queue_work_node - queue work on a "random" cpu for a given NUMA node
1562	* @node: NUMA node that we are targeting the work for
1563	* @wq: workqueue to use
1564	* @work: work to queue
1565	*
1566	* We queue the work to a "random" CPU within a given NUMA node. The basic
1567	* idea here is to provide a way to somehow associate work with a given
1568	* NUMA node.
1569	*
1570	* This function will only make a best effort attempt at getting this onto
1571	* the right NUMA node. If no node is requested or the requested node is
1572	* offline then we just fall back to standard queue_work behavior.
1573	*
1574	* Currently the "random" CPU ends up being the first available CPU in the
1575	* intersection of cpu_online_mask and the cpumask of the node, unless we
1576	* are running on the node. In that case we just use the current CPU.
1577	*
1578	* Return: %false if @work was already on a queue, %true otherwise.
1579	*/
1580	bool queue_work_node(int node, struct workqueue_struct *wq,
1581	struct work_struct *work)
1582	{
1583	unsigned long flags;
1584	bool ret = false;
1585
1586	/*
1587	* This current implementation is specific to unbound workqueues.
1588	* Specifically we only return the first available CPU for a given
1589	* node instead of cycling through individual CPUs within the node.
1590	*
1591	* If this is used with a per-cpu workqueue then the logic in
1592	* workqueue_select_cpu_near would need to be updated to allow for
1593	* some round robin type logic.
1594	*/
1595	WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND));
1596
1597	local_irq_save(flags);
1598
1599	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1600	int cpu = workqueue_select_cpu_near(node);
1601
1602	__queue_work(cpu, wq, work);
1603	ret = true;
1604	}
1605
1606	local_irq_restore(flags);
1607	return ret;
1608	}
1609	EXPORT_SYMBOL_GPL(queue_work_node);
1610
1611	void delayed_work_timer_fn(struct timer_list *t)
1612	{
1613	struct delayed_work *dwork = from_timer(dwork, t, timer);
1614
1615	/* should have been called from irqsafe timer with irq already off */
1616	__queue_work(dwork->cpu, dwork->wq, &dwork->work);
1617	}
1618	EXPORT_SYMBOL(delayed_work_timer_fn);
1619
1620	static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
1621	struct delayed_work *dwork, unsigned long delay)
1622	{
1623	struct timer_list *timer = &dwork->timer;
1624	struct work_struct *work = &dwork->work;
1625
1626	WARN_ON_ONCE(!wq);
1627	WARN_ON_ONCE(timer->function != delayed_work_timer_fn);
1628	WARN_ON_ONCE(timer_pending(timer));
1629	WARN_ON_ONCE(!list_empty(&work->entry));
1630
1631	/*
1632	* If @delay is 0, queue @dwork->work immediately. This is for
1633	* both optimization and correctness. The earliest @timer can
1634	* expire is on the closest next tick and delayed_work users depend
1635	* on that there's no such delay when @delay is 0.
1636	*/
1637	if (!delay) {
1638	__queue_work(cpu, wq, &dwork->work);
1639	return;
1640	}
1641
1642	dwork->wq = wq;
1643	dwork->cpu = cpu;
1644	timer->expires = jiffies + delay;
1645
1646	if (unlikely(cpu != WORK_CPU_UNBOUND))
1647	add_timer_on(timer, cpu);
1648	else
1649	add_timer(timer);
1650	}
1651
1652	/**
1653	* queue_delayed_work_on - queue work on specific CPU after delay
1654	* @cpu: CPU number to execute work on
1655	* @wq: workqueue to use
1656	* @dwork: work to queue
1657	* @delay: number of jiffies to wait before queueing
1658	*
1659	* Return: %false if @work was already on a queue, %true otherwise. If
1660	* @delay is zero and @dwork is idle, it will be scheduled for immediate
1661	* execution.
1662	*/
1663	bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
1664	struct delayed_work *dwork, unsigned long delay)
1665	{
1666	struct work_struct *work = &dwork->work;
1667	bool ret = false;
1668	unsigned long flags;
1669
1670	/* read the comment in __queue_work() */
1671	local_irq_save(flags);
1672
1673	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1674	__queue_delayed_work(cpu, wq, dwork, delay);
1675	ret = true;
1676	}
1677
1678	local_irq_restore(flags);
1679	return ret;
1680	}
1681	EXPORT_SYMBOL(queue_delayed_work_on);
1682
1683	/**
1684	* mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
1685	* @cpu: CPU number to execute work on
1686	* @wq: workqueue to use
1687	* @dwork: work to queue
1688	* @delay: number of jiffies to wait before queueing
1689	*
1690	* If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
1691	* modify @dwork's timer so that it expires after @delay. If @delay is
1692	* zero, @work is guaranteed to be scheduled immediately regardless of its
1693	* current state.
1694	*
1695	* Return: %false if @dwork was idle and queued, %true if @dwork was
1696	* pending and its timer was modified.
1697	*
1698	* This function is safe to call from any context including IRQ handler.
1699	* See try_to_grab_pending() for details.
1700	*/
1701	bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
1702	struct delayed_work *dwork, unsigned long delay)
1703	{
1704	unsigned long flags;
1705	int ret;
1706
1707	do {
1708	ret = try_to_grab_pending(&dwork->work, true, &flags);
1709	} while (unlikely(ret == -EAGAIN));
1710
1711	if (likely(ret >= 0)) {
1712	__queue_delayed_work(cpu, wq, dwork, delay);
1713	local_irq_restore(flags);
1714	}
1715
1716	/* -ENOENT from try_to_grab_pending() becomes %true */
1717	return ret;
1718	}
1719	EXPORT_SYMBOL_GPL(mod_delayed_work_on);
1720
1721	static void rcu_work_rcufn(struct rcu_head *rcu)
1722	{
1723	struct rcu_work *rwork = container_of(rcu, struct rcu_work, rcu);
1724
1725	/* read the comment in __queue_work() */
1726	local_irq_disable();
1727	__queue_work(WORK_CPU_UNBOUND, rwork->wq, &rwork->work);
1728	local_irq_enable();
1729	}
1730
1731	/**
1732	* queue_rcu_work - queue work after a RCU grace period
1733	* @wq: workqueue to use
1734	* @rwork: work to queue
1735	*
1736	* Return: %false if @rwork was already pending, %true otherwise. Note
1737	* that a full RCU grace period is guaranteed only after a %true return.
1738	* While @rwork is guaranteed to be executed after a %false return, the
1739	* execution may happen before a full RCU grace period has passed.
1740	*/
1741	bool queue_rcu_work(struct workqueue_struct wq, struct rcu_work rwork)
1742	{
1743	struct work_struct *work = &rwork->work;
1744
1745	if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
1746	rwork->wq = wq;
1747	call_rcu(&rwork->rcu, rcu_work_rcufn);
1748	return true;
1749	}
1750
1751	return false;
1752	}
1753	EXPORT_SYMBOL(queue_rcu_work);
1754
1755	/**
1756	* worker_enter_idle - enter idle state
1757	* @worker: worker which is entering idle state
1758	*
1759	* @worker is entering idle state. Update stats and idle timer if
1760	* necessary.
1761	*
1762	* LOCKING:
1763	* spin_lock_irq(pool->lock).
1764	*/
1765	static void worker_enter_idle(struct worker *worker)
1766	{
1767	struct worker_pool *pool = worker->pool;
1768
1769	if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) \|\|
1770	WARN_ON_ONCE(!list_empty(&worker->entry) &&
1771	(worker->hentry.next \|\| worker->hentry.pprev)))
1772	return;
1773
1774	/* can't use worker_set_flags(), also called from create_worker() */
1775	worker->flags \|= WORKER_IDLE;
1776	pool->nr_idle++;
1777	worker->last_active = jiffies;
1778
1779	/* idle_list is LIFO */
1780	list_add(&worker->entry, &pool->idle_list);
1781
1782	if (too_many_workers(pool) && !timer_pending(&pool->idle_timer))
1783	mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT);
1784
1785	/*
1786	* Sanity check nr_running. Because unbind_workers() releases
1787	* pool->lock between setting %WORKER_UNBOUND and zapping
1788	* nr_running, the warning may trigger spuriously. Check iff
1789	* unbind is not in progress.
1790	*/
1791	WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
1792	pool->nr_workers == pool->nr_idle &&
1793	atomic_read(&pool->nr_running));
1794	}
1795
1796	/**
1797	* worker_leave_idle - leave idle state
1798	* @worker: worker which is leaving idle state
1799	*
1800	* @worker is leaving idle state. Update stats.
1801	*
1802	* LOCKING:
1803	* spin_lock_irq(pool->lock).
1804	*/
1805	static void worker_leave_idle(struct worker *worker)
1806	{
1807	struct worker_pool *pool = worker->pool;
1808
1809	if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE)))
1810	return;
1811	worker_clr_flags(worker, WORKER_IDLE);
1812	pool->nr_idle--;
1813	list_del_init(&worker->entry);
1814	}
1815
1816	static struct worker *alloc_worker(int node)
1817	{
1818	struct worker *worker;
1819
1820	worker = kzalloc_node(sizeof(*worker), GFP_KERNEL, node);
1821	if (worker) {
1822	INIT_LIST_HEAD(&worker->entry);
1823	INIT_LIST_HEAD(&worker->scheduled);
1824	INIT_LIST_HEAD(&worker->node);
1825	/* on creation a worker is in !idle && prep state */
1826	worker->flags = WORKER_PREP;
1827	}
1828	return worker;
1829	}
1830
1831	/**
1832	* worker_attach_to_pool() - attach a worker to a pool
1833	* @worker: worker to be attached
1834	* @pool: the target pool
1835	*
1836	* Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and
1837	* cpu-binding of @worker are kept coordinated with the pool across
1838	* cpu-[un]hotplugs.
1839	*/
1840	static void worker_attach_to_pool(struct worker *worker,
1841	struct worker_pool *pool)
1842	{
1843	mutex_lock(&wq_pool_attach_mutex);
1844
1845	/*
1846	* set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
1847	* online CPUs. It'll be re-applied when any of the CPUs come up.
1848	*/
1849	set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask);
1850
1851	/*
1852	* The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains
1853	* stable across this function. See the comments above the flag
1854	* definition for details.
1855	*/
1856	if (pool->flags & POOL_DISASSOCIATED)
1857	worker->flags \|= WORKER_UNBOUND;
1858
1859	list_add_tail(&worker->node, &pool->workers);
1860	worker->pool = pool;
1861
1862	mutex_unlock(&wq_pool_attach_mutex);
1863	}
1864
1865	/**
1866	* worker_detach_from_pool() - detach a worker from its pool
1867	* @worker: worker which is attached to its pool
1868	*
1869	* Undo the attaching which had been done in worker_attach_to_pool(). The
1870	* caller worker shouldn't access to the pool after detached except it has
1871	* other reference to the pool.
1872	*/
1873	static void worker_detach_from_pool(struct worker *worker)
1874	{
1875	struct worker_pool *pool = worker->pool;
1876	struct completion *detach_completion = NULL;
1877
1878	mutex_lock(&wq_pool_attach_mutex);
1879
1880	list_del(&worker->node);
1881	worker->pool = NULL;
1882
1883	if (list_empty(&pool->workers))
1884	detach_completion = pool->detach_completion;
1885	mutex_unlock(&wq_pool_attach_mutex);
1886
1887	/* clear leftover flags without pool->lock after it is detached */
1888	worker->flags &= ~(WORKER_UNBOUND \| WORKER_REBOUND);
1889
1890	if (detach_completion)
1891	complete(detach_completion);
1892	}
1893
1894	/**
1895	* create_worker - create a new workqueue worker
1896	* @pool: pool the new worker will belong to
1897	*
1898	* Create and start a new worker which is attached to @pool.
1899	*
1900	* CONTEXT:
1901	* Might sleep. Does GFP_KERNEL allocations.
1902	*
1903	* Return:
1904	* Pointer to the newly created worker.
1905	*/
1906	static struct worker create_worker(struct worker_pool pool)
1907	{
1908	struct worker *worker = NULL;
1909	int id = -1;
1910	char id_buf[16];
1911
1912	/* ID is needed to determine kthread name */
1913	id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL);
1914	if (id < 0)
1915	goto fail;
1916
1917	worker = alloc_worker(pool->node);
1918	if (!worker)
1919	goto fail;
1920
1921	worker->id = id;
1922
1923	if (pool->cpu >= 0)
1924	snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id,
1925	pool->attrs->nice < 0 ? "H" : "");
1926	else
1927	snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id);
1928
1929	worker->task = kthread_create_on_node(worker_thread, worker, pool->node,
1930	"kworker/%s", id_buf);
1931	if (IS_ERR(worker->task))
1932	goto fail;
1933
1934	set_user_nice(worker->task, pool->attrs->nice);
1935	kthread_bind_mask(worker->task, pool->attrs->cpumask);
1936
1937	/* successful, attach the worker to the pool */
1938	worker_attach_to_pool(worker, pool);
1939
1940	/* start the newly created worker */
1941	spin_lock_irq(&pool->lock);
1942	worker->pool->nr_workers++;
1943	worker_enter_idle(worker);
1944	wake_up_process(worker->task);
1945	spin_unlock_irq(&pool->lock);
1946
1947	return worker;
1948
1949	fail:
1950	if (id >= 0)
1951	ida_simple_remove(&pool->worker_ida, id);
1952	kfree(worker);
1953	return NULL;
1954	}
1955
1956	/**
1957	* destroy_worker - destroy a workqueue worker
1958	* @worker: worker to be destroyed
1959	*
1960	* Destroy @worker and adjust @pool stats accordingly. The worker should
1961	* be idle.
1962	*
1963	* CONTEXT:
1964	* spin_lock_irq(pool->lock).
1965	*/
1966	static void destroy_worker(struct worker *worker)
1967	{
1968	struct worker_pool *pool = worker->pool;
1969
1970	lockdep_assert_held(&pool->lock);
1971
1972	/* sanity check frenzy */
1973	if (WARN_ON(worker->current_work) \|\|
1974	WARN_ON(!list_empty(&worker->scheduled)) \|\|
1975	WARN_ON(!(worker->flags & WORKER_IDLE)))
1976	return;
1977
1978	pool->nr_workers--;
1979	pool->nr_idle--;
1980
1981	list_del_init(&worker->entry);
1982	worker->flags \|= WORKER_DIE;
1983	wake_up_process(worker->task);
1984	}
1985
1986	static void idle_worker_timeout(struct timer_list *t)
1987	{
1988	struct worker_pool *pool = from_timer(pool, t, idle_timer);
1989
1990	spin_lock_irq(&pool->lock);
1991
1992	while (too_many_workers(pool)) {
1993	struct worker *worker;
1994	unsigned long expires;
1995
1996	/* idle_list is kept in LIFO order, check the last one */
1997	worker = list_entry(pool->idle_list.prev, struct worker, entry);
1998	expires = worker->last_active + IDLE_WORKER_TIMEOUT;
1999
2000	if (time_before(jiffies, expires)) {
2001	mod_timer(&pool->idle_timer, expires);
2002	break;
2003	}
2004
2005	destroy_worker(worker);
2006	}
2007
2008	spin_unlock_irq(&pool->lock);
2009	}
2010
2011	static void send_mayday(struct work_struct *work)
2012	{
2013	struct pool_workqueue *pwq = get_work_pwq(work);
2014	struct workqueue_struct *wq = pwq->wq;
2015
2016	lockdep_assert_held(&wq_mayday_lock);
2017
2018	if (!wq->rescuer)
2019	return;
2020
2021	/* mayday mayday mayday */
2022	if (list_empty(&pwq->mayday_node)) {
2023	/*
2024	* If @pwq is for an unbound wq, its base ref may be put at
2025	* any time due to an attribute change. Pin @pwq until the
2026	* rescuer is done with it.
2027	*/
2028	get_pwq(pwq);
2029	list_add_tail(&pwq->mayday_node, &wq->maydays);
2030	wake_up_process(wq->rescuer->task);
2031	}
2032	}
2033
2034	static void pool_mayday_timeout(struct timer_list *t)
2035	{
2036	struct worker_pool *pool = from_timer(pool, t, mayday_timer);
2037	struct work_struct *work;
2038
2039	spin_lock_irq(&pool->lock);
2040	spin_lock(&wq_mayday_lock); /* for wq->maydays */
2041
2042	if (need_to_create_worker(pool)) {
2043	/*
2044	* We've been trying to create a new worker but
2045	* haven't been successful. We might be hitting an
2046	* allocation deadlock. Send distress signals to
2047	* rescuers.
2048	*/
2049	list_for_each_entry(work, &pool->worklist, entry)
2050	send_mayday(work);
2051	}
2052
2053	spin_unlock(&wq_mayday_lock);
2054	spin_unlock_irq(&pool->lock);
2055
2056	mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
2057	}
2058
2059	/**
2060	* maybe_create_worker - create a new worker if necessary
2061	* @pool: pool to create a new worker for
2062	*
2063	* Create a new worker for @pool if necessary. @pool is guaranteed to
2064	* have at least one idle worker on return from this function. If
2065	* creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
2066	* sent to all rescuers with works scheduled on @pool to resolve
2067	* possible allocation deadlock.
2068	*
2069	* On return, need_to_create_worker() is guaranteed to be %false and
2070	* may_start_working() %true.
2071	*
2072	* LOCKING:
2073	* spin_lock_irq(pool->lock) which may be released and regrabbed
2074	* multiple times. Does GFP_KERNEL allocations. Called only from
2075	* manager.
2076	*/
2077	static void maybe_create_worker(struct worker_pool *pool)
2078	__releases(&pool->lock)
2079	__acquires(&pool->lock)
2080	{
2081	restart:
2082	spin_unlock_irq(&pool->lock);
2083
2084	/* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
2085	mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT);
2086
2087	while (true) {
2088	if (create_worker(pool) \|\| !need_to_create_worker(pool))
2089	break;
2090
2091	schedule_timeout_interruptible(CREATE_COOLDOWN);
2092
2093	if (!need_to_create_worker(pool))
2094	break;
2095	}
2096
2097	del_timer_sync(&pool->mayday_timer);
2098	spin_lock_irq(&pool->lock);
2099	/*
2100	* This is necessary even after a new worker was just successfully
2101	* created as @pool->lock was dropped and the new worker might have
2102	* already become busy.
2103	*/
2104	if (need_to_create_worker(pool))
2105	goto restart;
2106	}
2107
2108	/**
2109	* manage_workers - manage worker pool
2110	* @worker: self
2111	*
2112	* Assume the manager role and manage the worker pool @worker belongs
2113	* to. At any given time, there can be only zero or one manager per
2114	* pool. The exclusion is handled automatically by this function.
2115	*
2116	* The caller can safely start processing works on false return. On
2117	* true return, it's guaranteed that need_to_create_worker() is false
2118	* and may_start_working() is true.
2119	*
2120	* CONTEXT:
2121	* spin_lock_irq(pool->lock) which may be released and regrabbed
2122	* multiple times. Does GFP_KERNEL allocations.
2123	*
2124	* Return:
2125	* %false if the pool doesn't need management and the caller can safely
2126	* start processing works, %true if management function was performed and
2127	* the conditions that the caller verified before calling the function may
2128	* no longer be true.
2129	*/
2130	static bool manage_workers(struct worker *worker)
2131	{
2132	struct worker_pool *pool = worker->pool;
2133
2134	if (pool->flags & POOL_MANAGER_ACTIVE)
2135	return false;
2136
2137	pool->flags \|= POOL_MANAGER_ACTIVE;
2138	pool->manager = worker;
2139
2140	maybe_create_worker(pool);
2141
2142	pool->manager = NULL;
2143	pool->flags &= ~POOL_MANAGER_ACTIVE;
2144	wake_up(&wq_manager_wait);
2145	return true;
2146	}
2147
2148	/**
2149	* process_one_work - process single work
2150	* @worker: self
2151	* @work: work to process
2152	*
2153	* Process @work. This function contains all the logics necessary to
2154	* process a single work including synchronization against and
2155	* interaction with other workers on the same cpu, queueing and
2156	* flushing. As long as context requirement is met, any worker can
2157	* call this function to process a work.
2158	*
2159	* CONTEXT:
2160	* spin_lock_irq(pool->lock) which is released and regrabbed.
2161	*/
2162	static void process_one_work(struct worker worker, struct work_struct work)
2163	__releases(&pool->lock)
2164	__acquires(&pool->lock)
2165	{
2166	struct pool_workqueue *pwq = get_work_pwq(work);
2167	struct worker_pool *pool = worker->pool;
2168	bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE;
2169	int work_color;
2170	struct worker *collision;
2171	#ifdef CONFIG_LOCKDEP
2172	/*
2173	* It is permissible to free the struct work_struct from
2174	* inside the function that is called from it, this we need to
2175	* take into account for lockdep too. To avoid bogus "held
2176	* lock freed" warnings as well as problems when looking into
2177	* work->lockdep_map, make a copy and use that here.
2178	*/
2179	struct lockdep_map lockdep_map;
2180
2181	lockdep_copy_map(&lockdep_map, &work->lockdep_map);
2182	#endif
2183	/* ensure we're on the correct CPU */
2184	WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) &&
2185	raw_smp_processor_id() != pool->cpu);
2186
2187	/*
2188	* A single work shouldn't be executed concurrently by
2189	* multiple workers on a single cpu. Check whether anyone is
2190	* already processing the work. If so, defer the work to the
2191	* currently executing one.
2192	*/
2193	collision = find_worker_executing_work(pool, work);
2194	if (unlikely(collision)) {
2195	move_linked_works(work, &collision->scheduled, NULL);
2196	return;
2197	}
2198
2199	/* claim and dequeue */
2200	debug_work_deactivate(work);
2201	hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work);
2202	worker->current_work = work;
2203	worker->current_func = work->func;
2204	worker->current_pwq = pwq;
2205	work_color = get_work_color(work);
2206
2207	/*
2208	* Record wq name for cmdline and debug reporting, may get
2209	* overridden through set_worker_desc().
2210	*/
2211	strscpy(worker->desc, pwq->wq->name, WORKER_DESC_LEN);
2212
2213	list_del_init(&work->entry);
2214
2215	/*
2216	* CPU intensive works don't participate in concurrency management.
2217	* They're the scheduler's responsibility. This takes @worker out
2218	* of concurrency management and the next code block will chain
2219	* execution of the pending work items.
2220	*/
2221	if (unlikely(cpu_intensive))
2222	worker_set_flags(worker, WORKER_CPU_INTENSIVE);
2223
2224	/*
2225	* Wake up another worker if necessary. The condition is always
2226	* false for normal per-cpu workers since nr_running would always
2227	* be >= 1 at this point. This is used to chain execution of the
2228	* pending work items for WORKER_NOT_RUNNING workers such as the
2229	* UNBOUND and CPU_INTENSIVE ones.
2230	*/
2231	if (need_more_worker(pool))
2232	wake_up_worker(pool);
2233
2234	/*
2235	* Record the last pool and clear PENDING which should be the last
2236	* update to @work. Also, do this inside @pool->lock so that
2237	* PENDING and queued state changes happen together while IRQ is
2238	* disabled.
2239	*/
2240	set_work_pool_and_clear_pending(work, pool->id);
2241
2242	spin_unlock_irq(&pool->lock);
2243
2244	lock_map_acquire(&pwq->wq->lockdep_map);
2245	lock_map_acquire(&lockdep_map);
2246	/*
2247	* Strictly speaking we should mark the invariant state without holding
2248	* any locks, that is, before these two lock_map_acquire()'s.
2249	*
2250	* However, that would result in:
2251	*
2252	* A(W1)
2253	* WFC(C)
2254	* A(W1)
2255	* C(C)
2256	*
2257	* Which would create W1->C->W1 dependencies, even though there is no
2258	* actual deadlock possible. There are two solutions, using a
2259	* read-recursive acquire on the work(queue) 'locks', but this will then
2260	* hit the lockdep limitation on recursive locks, or simply discard
2261	* these locks.
2262	*
2263	* AFAICT there is no possible deadlock scenario between the
2264	* flush_work() and complete() primitives (except for single-threaded
2265	* workqueues), so hiding them isn't a problem.
2266	*/
2267	lockdep_invariant_state(true);
2268	trace_workqueue_execute_start(work);
2269	worker->current_func(work);
2270	/*
2271	* While we must be careful to not use "work" after this, the trace
2272	* point will only record its address.
2273	*/
2274	trace_workqueue_execute_end(work);
2275	lock_map_release(&lockdep_map);
2276	lock_map_release(&pwq->wq->lockdep_map);
2277
2278	if (unlikely(in_atomic() \|\| lockdep_depth(current) > 0)) {
2279	pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
2280	" last function: %ps\n",
2281	current->comm, preempt_count(), task_pid_nr(current),
2282	worker->current_func);
2283	debug_show_held_locks(current);
2284	dump_stack();
2285	}
2286
2287	/*
2288	* The following prevents a kworker from hogging CPU on !PREEMPT
2289	* kernels, where a requeueing work item waiting for something to
2290	* happen could deadlock with stop_machine as such work item could
2291	* indefinitely requeue itself while all other CPUs are trapped in
2292	* stop_machine. At the same time, report a quiescent RCU state so
2293	* the same condition doesn't freeze RCU.
2294	*/
2295	cond_resched();
2296
2297	spin_lock_irq(&pool->lock);
2298
2299	/* clear cpu intensive status */
2300	if (unlikely(cpu_intensive))
2301	worker_clr_flags(worker, WORKER_CPU_INTENSIVE);
2302
2303	/* tag the worker for identification in schedule() */
2304	worker->last_func = worker->current_func;
2305
2306	/* we're done with it, release */
2307	hash_del(&worker->hentry);
2308	worker->current_work = NULL;
2309	worker->current_func = NULL;
2310	worker->current_pwq = NULL;
2311	pwq_dec_nr_in_flight(pwq, work_color);
2312	}
2313
2314	/**
2315	* process_scheduled_works - process scheduled works
2316	* @worker: self
2317	*
2318	* Process all scheduled works. Please note that the scheduled list
2319	* may change while processing a work, so this function repeatedly
2320	* fetches a work from the top and executes it.
2321	*
2322	* CONTEXT:
2323	* spin_lock_irq(pool->lock) which may be released and regrabbed
2324	* multiple times.
2325	*/
2326	static void process_scheduled_works(struct worker *worker)
2327	{
2328	while (!list_empty(&worker->scheduled)) {
2329	struct work_struct *work = list_first_entry(&worker->scheduled,
2330	struct work_struct, entry);
2331	process_one_work(worker, work);
2332	}
2333	}
2334
2335	static void set_pf_worker(bool val)
2336	{
2337	mutex_lock(&wq_pool_attach_mutex);
2338	if (val)
2339	current->flags \|= PF_WQ_WORKER;
2340	else
2341	current->flags &= ~PF_WQ_WORKER;
2342	mutex_unlock(&wq_pool_attach_mutex);
2343	}
2344
2345	/**
2346	* worker_thread - the worker thread function
2347	* @__worker: self
2348	*
2349	* The worker thread function. All workers belong to a worker_pool -
2350	* either a per-cpu one or dynamic unbound one. These workers process all
2351	* work items regardless of their specific target workqueue. The only
2352	* exception is work items which belong to workqueues with a rescuer which
2353	* will be explained in rescuer_thread().
2354	*
2355	* Return: 0
2356	*/
2357	static int worker_thread(void *__worker)
2358	{
2359	struct worker *worker = __worker;
2360	struct worker_pool *pool = worker->pool;
2361
2362	/* tell the scheduler that this is a workqueue worker */
2363	set_pf_worker(true);
2364	woke_up:
2365	spin_lock_irq(&pool->lock);
2366
2367	/* am I supposed to die? */
2368	if (unlikely(worker->flags & WORKER_DIE)) {
2369	spin_unlock_irq(&pool->lock);
2370	WARN_ON_ONCE(!list_empty(&worker->entry));
2371	set_pf_worker(false);
2372
2373	set_task_comm(worker->task, "kworker/dying");
2374	ida_simple_remove(&pool->worker_ida, worker->id);
2375	worker_detach_from_pool(worker);
2376	kfree(worker);
2377	return 0;
2378	}
2379
2380	worker_leave_idle(worker);
2381	recheck:
2382	/* no more worker necessary? */
2383	if (!need_more_worker(pool))
2384	goto sleep;
2385
2386	/* do we need to manage? */
2387	if (unlikely(!may_start_working(pool)) && manage_workers(worker))
2388	goto recheck;
2389
2390	/*
2391	* ->scheduled list can only be filled while a worker is
2392	* preparing to process a work or actually processing it.
2393	* Make sure nobody diddled with it while I was sleeping.
2394	*/
2395	WARN_ON_ONCE(!list_empty(&worker->scheduled));
2396
2397	/*
2398	* Finish PREP stage. We're guaranteed to have at least one idle
2399	* worker or that someone else has already assumed the manager
2400	* role. This is where @worker starts participating in concurrency
2401	* management if applicable and concurrency management is restored
2402	* after being rebound. See rebind_workers() for details.
2403	*/
2404	worker_clr_flags(worker, WORKER_PREP \| WORKER_REBOUND);
2405
2406	do {
2407	struct work_struct *work =
2408	list_first_entry(&pool->worklist,
2409	struct work_struct, entry);
2410
2411	pool->watchdog_ts = jiffies;
2412
2413	if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) {
2414	/* optimization path, not strictly necessary */
2415	process_one_work(worker, work);
2416	if (unlikely(!list_empty(&worker->scheduled)))
2417	process_scheduled_works(worker);
2418	} else {
2419	move_linked_works(work, &worker->scheduled, NULL);
2420	process_scheduled_works(worker);
2421	}
2422	} while (keep_working(pool));
2423
2424	worker_set_flags(worker, WORKER_PREP);
2425	sleep:
2426	/*
2427	* pool->lock is held and there's no work to process and no need to
2428	* manage, sleep. Workers are woken up only while holding
2429	* pool->lock or from local cpu, so setting the current state
2430	* before releasing pool->lock is enough to prevent losing any
2431	* event.
2432	*/
2433	worker_enter_idle(worker);
2434	__set_current_state(TASK_IDLE);
2435	spin_unlock_irq(&pool->lock);
2436	schedule();
2437	goto woke_up;
2438	}
2439
2440	/**
2441	* rescuer_thread - the rescuer thread function
2442	* @__rescuer: self
2443	*
2444	* Workqueue rescuer thread function. There's one rescuer for each
2445	* workqueue which has WQ_MEM_RECLAIM set.
2446	*
2447	* Regular work processing on a pool may block trying to create a new
2448	* worker which uses GFP_KERNEL allocation which has slight chance of
2449	* developing into deadlock if some works currently on the same queue
2450	* need to be processed to satisfy the GFP_KERNEL allocation. This is
2451	* the problem rescuer solves.
2452	*
2453	* When such condition is possible, the pool summons rescuers of all
2454	* workqueues which have works queued on the pool and let them process
2455	* those works so that forward progress can be guaranteed.
2456	*
2457	* This should happen rarely.
2458	*
2459	* Return: 0
2460	*/
2461	static int rescuer_thread(void *__rescuer)
2462	{
2463	struct worker *rescuer = __rescuer;
2464	struct workqueue_struct *wq = rescuer->rescue_wq;
2465	struct list_head *scheduled = &rescuer->scheduled;
2466	bool should_stop;
2467
2468	set_user_nice(current, RESCUER_NICE_LEVEL);
2469
2470	/*
2471	* Mark rescuer as worker too. As WORKER_PREP is never cleared, it
2472	* doesn't participate in concurrency management.
2473	*/
2474	set_pf_worker(true);
2475	repeat:
2476	set_current_state(TASK_IDLE);
2477
2478	/*
2479	* By the time the rescuer is requested to stop, the workqueue
2480	* shouldn't have any work pending, but @wq->maydays may still have
2481	* pwq(s) queued. This can happen by non-rescuer workers consuming
2482	* all the work items before the rescuer got to them. Go through
2483	* @wq->maydays processing before acting on should_stop so that the
2484	* list is always empty on exit.
2485	*/
2486	should_stop = kthread_should_stop();
2487
2488	/* see whether any pwq is asking for help */
2489	spin_lock_irq(&wq_mayday_lock);
2490
2491	while (!list_empty(&wq->maydays)) {
2492	struct pool_workqueue *pwq = list_first_entry(&wq->maydays,
2493	struct pool_workqueue, mayday_node);
2494	struct worker_pool *pool = pwq->pool;
2495	struct work_struct work, n;
2496	bool first = true;
2497
2498	__set_current_state(TASK_RUNNING);
2499	list_del_init(&pwq->mayday_node);
2500
2501	spin_unlock_irq(&wq_mayday_lock);
2502
2503	worker_attach_to_pool(rescuer, pool);
2504
2505	spin_lock_irq(&pool->lock);
2506
2507	/*
2508	* Slurp in all works issued via this workqueue and
2509	* process'em.
2510	*/
2511	WARN_ON_ONCE(!list_empty(scheduled));
2512	list_for_each_entry_safe(work, n, &pool->worklist, entry) {
2513	if (get_work_pwq(work) == pwq) {
2514	if (first)
2515	pool->watchdog_ts = jiffies;
2516	move_linked_works(work, scheduled, &n);
2517	}
2518	first = false;
2519	}
2520
2521	if (!list_empty(scheduled)) {
2522	process_scheduled_works(rescuer);
2523
2524	/*
2525	* The above execution of rescued work items could
2526	* have created more to rescue through
2527	* pwq_activate_first_delayed() or chained
2528	* queueing. Let's put @pwq back on mayday list so
2529	* that such back-to-back work items, which may be
2530	* being used to relieve memory pressure, don't
2531	* incur MAYDAY_INTERVAL delay inbetween.
2532	*/
2533	if (need_to_create_worker(pool)) {
2534	spin_lock(&wq_mayday_lock);
2535	get_pwq(pwq);
2536	list_move_tail(&pwq->mayday_node, &wq->maydays);
2537	spin_unlock(&wq_mayday_lock);
2538	}
2539	}
2540
2541	/*
2542	* Put the reference grabbed by send_mayday(). @pool won't
2543	* go away while we're still attached to it.
2544	*/
2545	put_pwq(pwq);
2546
2547	/*
2548	* Leave this pool. If need_more_worker() is %true, notify a
2549	* regular worker; otherwise, we end up with 0 concurrency
2550	* and stalling the execution.
2551	*/
2552	if (need_more_worker(pool))
2553	wake_up_worker(pool);
2554
2555	spin_unlock_irq(&pool->lock);
2556
2557	worker_detach_from_pool(rescuer);
2558
2559	spin_lock_irq(&wq_mayday_lock);
2560	}
2561
2562	spin_unlock_irq(&wq_mayday_lock);
2563
2564	if (should_stop) {
2565	__set_current_state(TASK_RUNNING);
2566	set_pf_worker(false);
2567	return 0;
2568	}
2569
2570	/* rescuers should never participate in concurrency management */
2571	WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING));
2572	schedule();
2573	goto repeat;
2574	}
2575
2576	/**
2577	* check_flush_dependency - check for flush dependency sanity
2578	* @target_wq: workqueue being flushed
2579	* @target_work: work item being flushed (NULL for workqueue flushes)
2580	*
2581	* %current is trying to flush the whole @target_wq or @target_work on it.
2582	* If @target_wq doesn't have %WQ_MEM_RECLAIM, verify that %current is not
2583	* reclaiming memory or running on a workqueue which doesn't have
2584	* %WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to
2585	* a deadlock.
2586	*/
2587	static void check_flush_dependency(struct workqueue_struct *target_wq,
2588	struct work_struct *target_work)
2589	{
2590	work_func_t target_func = target_work ? target_work->func : NULL;
2591	struct worker *worker;
2592
2593	if (target_wq->flags & WQ_MEM_RECLAIM)
2594	return;
2595
2596	worker = current_wq_worker();
2597
2598	WARN_ONCE(current->flags & PF_MEMALLOC,
2599	"workqueue: PF_MEMALLOC task %d(%s) is flushing !WQ_MEM_RECLAIM %s:%ps",
2600	current->pid, current->comm, target_wq->name, target_func);
2601	WARN_ONCE(worker && ((worker->current_pwq->wq->flags &
2602	(WQ_MEM_RECLAIM \| __WQ_LEGACY)) == WQ_MEM_RECLAIM),
2603	"workqueue: WQ_MEM_RECLAIM %s:%ps is flushing !WQ_MEM_RECLAIM %s:%ps",
2604	worker->current_pwq->wq->name, worker->current_func,
2605	target_wq->name, target_func);
2606	}
2607
2608	struct wq_barrier {
2609	struct work_struct work;
2610	struct completion done;
2611	struct task_struct task; / purely informational */
2612	};
2613
2614	static void wq_barrier_func(struct work_struct *work)
2615	{
2616	struct wq_barrier *barr = container_of(work, struct wq_barrier, work);
2617	complete(&barr->done);
2618	}
2619
2620	/**
2621	* insert_wq_barrier - insert a barrier work
2622	* @pwq: pwq to insert barrier into
2623	* @barr: wq_barrier to insert
2624	* @target: target work to attach @barr to
2625	* @worker: worker currently executing @target, NULL if @target is not executing
2626	*
2627	* @barr is linked to @target such that @barr is completed only after
2628	* @target finishes execution. Please note that the ordering
2629	* guarantee is observed only with respect to @target and on the local
2630	* cpu.
2631	*
2632	* Currently, a queued barrier can't be canceled. This is because
2633	* try_to_grab_pending() can't determine whether the work to be
2634	* grabbed is at the head of the queue and thus can't clear LINKED
2635	* flag of the previous work while there must be a valid next work
2636	* after a work with LINKED flag set.
2637	*
2638	* Note that when @worker is non-NULL, @target may be modified
2639	* underneath us, so we can't reliably determine pwq from @target.
2640	*
2641	* CONTEXT:
2642	* spin_lock_irq(pool->lock).
2643	*/
2644	static void insert_wq_barrier(struct pool_workqueue *pwq,
2645	struct wq_barrier *barr,
2646	struct work_struct target, struct worker worker)
2647	{
2648	struct list_head *head;
2649	unsigned int linked = 0;
2650
2651	/*
2652	* debugobject calls are safe here even with pool->lock locked
2653	* as we know for sure that this will not trigger any of the
2654	* checks and call back into the fixup functions where we
2655	* might deadlock.
2656	*/
2657	INIT_WORK_ONSTACK(&barr->work, wq_barrier_func);
2658	__set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work));
2659
2660	init_completion_map(&barr->done, &target->lockdep_map);
2661
2662	barr->task = current;
2663
2664	/*
2665	* If @target is currently being executed, schedule the
2666	* barrier to the worker; otherwise, put it after @target.
2667	*/
2668	if (worker)
2669	head = worker->scheduled.next;
2670	else {
2671	unsigned long *bits = work_data_bits(target);
2672
2673	head = target->entry.next;
2674	/* there can already be other linked works, inherit and set */
2675	linked = *bits & WORK_STRUCT_LINKED;
2676	__set_bit(WORK_STRUCT_LINKED_BIT, bits);
2677	}
2678
2679	debug_work_activate(&barr->work);
2680	insert_work(pwq, &barr->work, head,
2681	work_color_to_flags(WORK_NO_COLOR) \| linked);
2682	}
2683
2684	/**
2685	* flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
2686	* @wq: workqueue being flushed
2687	* @flush_color: new flush color, < 0 for no-op
2688	* @work_color: new work color, < 0 for no-op
2689	*
2690	* Prepare pwqs for workqueue flushing.
2691	*
2692	* If @flush_color is non-negative, flush_color on all pwqs should be
2693	* -1. If no pwq has in-flight commands at the specified color, all
2694	* pwq->flush_color's stay at -1 and %false is returned. If any pwq
2695	* has in flight commands, its pwq->flush_color is set to
2696	* @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
2697	* wakeup logic is armed and %true is returned.
2698	*
2699	* The caller should have initialized @wq->first_flusher prior to
2700	* calling this function with non-negative @flush_color. If
2701	* @flush_color is negative, no flush color update is done and %false
2702	* is returned.
2703	*
2704	* If @work_color is non-negative, all pwqs should have the same
2705	* work_color which is previous to @work_color and all will be
2706	* advanced to @work_color.
2707	*
2708	* CONTEXT:
2709	* mutex_lock(wq->mutex).
2710	*
2711	* Return:
2712	* %true if @flush_color >= 0 and there's something to flush. %false
2713	* otherwise.
2714	*/
2715	static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq,
2716	int flush_color, int work_color)
2717	{
2718	bool wait = false;
2719	struct pool_workqueue *pwq;
2720
2721	if (flush_color >= 0) {
2722	WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush));
2723	atomic_set(&wq->nr_pwqs_to_flush, 1);
2724	}
2725
2726	for_each_pwq(pwq, wq) {
2727	struct worker_pool *pool = pwq->pool;
2728
2729	spin_lock_irq(&pool->lock);
2730
2731	if (flush_color >= 0) {
2732	WARN_ON_ONCE(pwq->flush_color != -1);
2733
2734	if (pwq->nr_in_flight[flush_color]) {
2735	pwq->flush_color = flush_color;
2736	atomic_inc(&wq->nr_pwqs_to_flush);
2737	wait = true;
2738	}
2739	}
2740
2741	if (work_color >= 0) {
2742	WARN_ON_ONCE(work_color != work_next_color(pwq->work_color));
2743	pwq->work_color = work_color;
2744	}
2745
2746	spin_unlock_irq(&pool->lock);
2747	}
2748
2749	if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush))
2750	complete(&wq->first_flusher->done);
2751
2752	return wait;
2753	}
2754
2755	/**
2756	* flush_workqueue - ensure that any scheduled work has run to completion.
2757	* @wq: workqueue to flush
2758	*
2759	* This function sleeps until all work items which were queued on entry
2760	* have finished execution, but it is not livelocked by new incoming ones.
2761	*/
2762	void flush_workqueue(struct workqueue_struct *wq)
2763	{
2764	struct wq_flusher this_flusher = {
2765	.list = LIST_HEAD_INIT(this_flusher.list),
2766	.flush_color = -1,
2767	.done = COMPLETION_INITIALIZER_ONSTACK_MAP(this_flusher.done, wq->lockdep_map),
2768	};
2769	int next_color;
2770
2771	if (WARN_ON(!wq_online))
2772	return;
2773
2774	lock_map_acquire(&wq->lockdep_map);
2775	lock_map_release(&wq->lockdep_map);
2776
2777	mutex_lock(&wq->mutex);
2778
2779	/*
2780	* Start-to-wait phase
2781	*/
2782	next_color = work_next_color(wq->work_color);
2783
2784	if (next_color != wq->flush_color) {
2785	/*
2786	* Color space is not full. The current work_color
2787	* becomes our flush_color and work_color is advanced
2788	* by one.
2789	*/
2790	WARN_ON_ONCE(!list_empty(&wq->flusher_overflow));
2791	this_flusher.flush_color = wq->work_color;
2792	wq->work_color = next_color;
2793
2794	if (!wq->first_flusher) {
2795	/* no flush in progress, become the first flusher */
2796	WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
2797
2798	wq->first_flusher = &this_flusher;
2799
2800	if (!flush_workqueue_prep_pwqs(wq, wq->flush_color,
2801	wq->work_color)) {
2802	/* nothing to flush, done */
2803	wq->flush_color = next_color;
2804	wq->first_flusher = NULL;
2805	goto out_unlock;
2806	}
2807	} else {
2808	/* wait in queue */
2809	WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color);
2810	list_add_tail(&this_flusher.list, &wq->flusher_queue);
2811	flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
2812	}
2813	} else {
2814	/*
2815	* Oops, color space is full, wait on overflow queue.
2816	* The next flush completion will assign us
2817	* flush_color and transfer to flusher_queue.
2818	*/
2819	list_add_tail(&this_flusher.list, &wq->flusher_overflow);
2820	}
2821
2822	check_flush_dependency(wq, NULL);
2823
2824	mutex_unlock(&wq->mutex);
2825
2826	wait_for_completion(&this_flusher.done);
2827
2828	/*
2829	* Wake-up-and-cascade phase
2830	*
2831	* First flushers are responsible for cascading flushes and
2832	* handling overflow. Non-first flushers can simply return.
2833	*/
2834	if (wq->first_flusher != &this_flusher)
2835	return;
2836
2837	mutex_lock(&wq->mutex);
2838
2839	/* we might have raced, check again with mutex held */
2840	if (wq->first_flusher != &this_flusher)
2841	goto out_unlock;
2842
2843	wq->first_flusher = NULL;
2844
2845	WARN_ON_ONCE(!list_empty(&this_flusher.list));
2846	WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color);
2847
2848	while (true) {
2849	struct wq_flusher next, tmp;
2850
2851	/* complete all the flushers sharing the current flush color */
2852	list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) {
2853	if (next->flush_color != wq->flush_color)
2854	break;
2855	list_del_init(&next->list);
2856	complete(&next->done);
2857	}
2858
2859	WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) &&
2860	wq->flush_color != work_next_color(wq->work_color));
2861
2862	/* this flush_color is finished, advance by one */
2863	wq->flush_color = work_next_color(wq->flush_color);
2864
2865	/* one color has been freed, handle overflow queue */
2866	if (!list_empty(&wq->flusher_overflow)) {
2867	/*
2868	* Assign the same color to all overflowed
2869	* flushers, advance work_color and append to
2870	* flusher_queue. This is the start-to-wait
2871	* phase for these overflowed flushers.
2872	*/
2873	list_for_each_entry(tmp, &wq->flusher_overflow, list)
2874	tmp->flush_color = wq->work_color;
2875
2876	wq->work_color = work_next_color(wq->work_color);
2877
2878	list_splice_tail_init(&wq->flusher_overflow,
2879	&wq->flusher_queue);
2880	flush_workqueue_prep_pwqs(wq, -1, wq->work_color);
2881	}
2882
2883	if (list_empty(&wq->flusher_queue)) {
2884	WARN_ON_ONCE(wq->flush_color != wq->work_color);
2885	break;
2886	}
2887
2888	/*
2889	* Need to flush more colors. Make the next flusher
2890	* the new first flusher and arm pwqs.
2891	*/
2892	WARN_ON_ONCE(wq->flush_color == wq->work_color);
2893	WARN_ON_ONCE(wq->flush_color != next->flush_color);
2894
2895	list_del_init(&next->list);
2896	wq->first_flusher = next;
2897
2898	if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1))
2899	break;
2900
2901	/*
2902	* Meh... this color is already done, clear first
2903	* flusher and repeat cascading.
2904	*/
2905	wq->first_flusher = NULL;
2906	}
2907
2908	out_unlock:
2909	mutex_unlock(&wq->mutex);
2910	}
2911	EXPORT_SYMBOL(flush_workqueue);
2912
2913	/**
2914	* drain_workqueue - drain a workqueue
2915	* @wq: workqueue to drain
2916	*
2917	* Wait until the workqueue becomes empty. While draining is in progress,
2918	* only chain queueing is allowed. IOW, only currently pending or running
2919	* work items on @wq can queue further work items on it. @wq is flushed
2920	* repeatedly until it becomes empty. The number of flushing is determined
2921	* by the depth of chaining and should be relatively short. Whine if it
2922	* takes too long.
2923	*/
2924	void drain_workqueue(struct workqueue_struct *wq)
2925	{
2926	unsigned int flush_cnt = 0;
2927	struct pool_workqueue *pwq;
2928
2929	/*
2930	* __queue_work() needs to test whether there are drainers, is much
2931	* hotter than drain_workqueue() and already looks at @wq->flags.
2932	* Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
2933	*/
2934	mutex_lock(&wq->mutex);
2935	if (!wq->nr_drainers++)
2936	wq->flags \|= __WQ_DRAINING;
2937	mutex_unlock(&wq->mutex);
2938	reflush:
2939	flush_workqueue(wq);
2940
2941	mutex_lock(&wq->mutex);
2942
2943	for_each_pwq(pwq, wq) {
2944	bool drained;
2945
2946	spin_lock_irq(&pwq->pool->lock);
2947	drained = !pwq->nr_active && list_empty(&pwq->delayed_works);
2948	spin_unlock_irq(&pwq->pool->lock);
2949
2950	if (drained)
2951	continue;
2952
2953	if (++flush_cnt == 10 \|\|
2954	(flush_cnt % 100 == 0 && flush_cnt <= 1000))
2955	pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
2956	wq->name, flush_cnt);
2957
2958	mutex_unlock(&wq->mutex);
2959	goto reflush;
2960	}
2961
2962	if (!--wq->nr_drainers)
2963	wq->flags &= ~__WQ_DRAINING;
2964	mutex_unlock(&wq->mutex);
2965	}
2966	EXPORT_SYMBOL_GPL(drain_workqueue);
2967
2968	static bool start_flush_work(struct work_struct work, struct wq_barrier barr,
2969	bool from_cancel)
2970	{
2971	struct worker *worker = NULL;
2972	struct worker_pool *pool;
2973	struct pool_workqueue *pwq;
2974
2975	might_sleep();
2976
2977	rcu_read_lock();
2978	pool = get_work_pool(work);
2979	if (!pool) {
2980	rcu_read_unlock();
2981	return false;
2982	}
2983
2984	spin_lock_irq(&pool->lock);
2985	/* see the comment in try_to_grab_pending() with the same code */
2986	pwq = get_work_pwq(work);
2987	if (pwq) {
2988	if (unlikely(pwq->pool != pool))
2989	goto already_gone;
2990	} else {
2991	worker = find_worker_executing_work(pool, work);
2992	if (!worker)
2993	goto already_gone;
2994	pwq = worker->current_pwq;
2995	}
2996
2997	check_flush_dependency(pwq->wq, work);
2998
2999	insert_wq_barrier(pwq, barr, work, worker);
3000	spin_unlock_irq(&pool->lock);
3001
3002	/*
3003	* Force a lock recursion deadlock when using flush_work() inside a
3004	* single-threaded or rescuer equipped workqueue.
3005	*
3006	* For single threaded workqueues the deadlock happens when the work
3007	* is after the work issuing the flush_work(). For rescuer equipped
3008	* workqueues the deadlock happens when the rescuer stalls, blocking
3009	* forward progress.
3010	*/
3011	if (!from_cancel &&
3012	(pwq->wq->saved_max_active == 1 \|\| pwq->wq->rescuer)) {
3013	lock_map_acquire(&pwq->wq->lockdep_map);
3014	lock_map_release(&pwq->wq->lockdep_map);
3015	}
3016	rcu_read_unlock();
3017	return true;
3018	already_gone:
3019	spin_unlock_irq(&pool->lock);
3020	rcu_read_unlock();
3021	return false;
3022	}
3023
3024	static bool __flush_work(struct work_struct *work, bool from_cancel)
3025	{
3026	struct wq_barrier barr;
3027
3028	if (WARN_ON(!wq_online))
3029	return false;
3030
3031	if (WARN_ON(!work->func))
3032	return false;
3033
3034	if (!from_cancel) {
3035	lock_map_acquire(&work->lockdep_map);
3036	lock_map_release(&work->lockdep_map);
3037	}
3038
3039	if (start_flush_work(work, &barr, from_cancel)) {
3040	wait_for_completion(&barr.done);
3041	destroy_work_on_stack(&barr.work);
3042	return true;
3043	} else {
3044	return false;
3045	}
3046	}
3047
3048	/**
3049	* flush_work - wait for a work to finish executing the last queueing instance
3050	* @work: the work to flush
3051	*
3052	* Wait until @work has finished execution. @work is guaranteed to be idle
3053	* on return if it hasn't been requeued since flush started.
3054	*
3055	* Return:
3056	* %true if flush_work() waited for the work to finish execution,
3057	* %false if it was already idle.
3058	*/
3059	bool flush_work(struct work_struct *work)
3060	{
3061	return __flush_work(work, false);
3062	}
3063	EXPORT_SYMBOL_GPL(flush_work);
3064
3065	struct cwt_wait {
3066	wait_queue_entry_t wait;
3067	struct work_struct *work;
3068	};
3069
3070	static int cwt_wakefn(wait_queue_entry_t wait, unsigned mode, int sync, void key)
3071	{
3072	struct cwt_wait *cwait = container_of(wait, struct cwt_wait, wait);
3073
3074	if (cwait->work != key)
3075	return 0;
3076	return autoremove_wake_function(wait, mode, sync, key);
3077	}
3078
3079	static bool __cancel_work_timer(struct work_struct *work, bool is_dwork)
3080	{
3081	static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq);
3082	unsigned long flags;
3083	int ret;
3084
3085	do {
3086	ret = try_to_grab_pending(work, is_dwork, &flags);
3087	/*
3088	* If someone else is already canceling, wait for it to
3089	* finish. flush_work() doesn't work for PREEMPT_NONE
3090	* because we may get scheduled between @work's completion
3091	* and the other canceling task resuming and clearing
3092	* CANCELING - flush_work() will return false immediately
3093	* as @work is no longer busy, try_to_grab_pending() will
3094	* return -ENOENT as @work is still being canceled and the
3095	* other canceling task won't be able to clear CANCELING as
3096	* we're hogging the CPU.
3097	*
3098	* Let's wait for completion using a waitqueue. As this
3099	* may lead to the thundering herd problem, use a custom
3100	* wake function which matches @work along with exclusive
3101	* wait and wakeup.
3102	*/
3103	if (unlikely(ret == -ENOENT)) {
3104	struct cwt_wait cwait;
3105
3106	init_wait(&cwait.wait);
3107	cwait.wait.func = cwt_wakefn;
3108	cwait.work = work;
3109
3110	prepare_to_wait_exclusive(&cancel_waitq, &cwait.wait,
3111	TASK_UNINTERRUPTIBLE);
3112	if (work_is_canceling(work))
3113	schedule();
3114	finish_wait(&cancel_waitq, &cwait.wait);
3115	}
3116	} while (unlikely(ret < 0));
3117
3118	/* tell other tasks trying to grab @work to back off */
3119	mark_work_canceling(work);
3120	local_irq_restore(flags);
3121
3122	/*
3123	* This allows canceling during early boot. We know that @work
3124	* isn't executing.
3125	*/
3126	if (wq_online)
3127	__flush_work(work, true);
3128
3129	clear_work_data(work);
3130
3131	/*
3132	* Paired with prepare_to_wait() above so that either
3133	* waitqueue_active() is visible here or !work_is_canceling() is
3134	* visible there.
3135	*/
3136	smp_mb();
3137	if (waitqueue_active(&cancel_waitq))
3138	__wake_up(&cancel_waitq, TASK_NORMAL, 1, work);
3139
3140	return ret;
3141	}
3142
3143	/**
3144	* cancel_work_sync - cancel a work and wait for it to finish
3145	* @work: the work to cancel
3146	*
3147	* Cancel @work and wait for its execution to finish. This function
3148	* can be used even if the work re-queues itself or migrates to
3149	* another workqueue. On return from this function, @work is
3150	* guaranteed to be not pending or executing on any CPU.
3151	*
3152	* cancel_work_sync(&delayed_work->work) must not be used for
3153	* delayed_work's. Use cancel_delayed_work_sync() instead.
3154	*
3155	* The caller must ensure that the workqueue on which @work was last
3156	* queued can't be destroyed before this function returns.
3157	*
3158	* Return:
3159	* %true if @work was pending, %false otherwise.
3160	*/
3161	bool cancel_work_sync(struct work_struct *work)
3162	{
3163	return __cancel_work_timer(work, false);
3164	}
3165	EXPORT_SYMBOL_GPL(cancel_work_sync);
3166
3167	/**
3168	* flush_delayed_work - wait for a dwork to finish executing the last queueing
3169	* @dwork: the delayed work to flush
3170	*
3171	* Delayed timer is cancelled and the pending work is queued for
3172	* immediate execution. Like flush_work(), this function only
3173	* considers the last queueing instance of @dwork.
3174	*
3175	* Return:
3176	* %true if flush_work() waited for the work to finish execution,
3177	* %false if it was already idle.
3178	*/
3179	bool flush_delayed_work(struct delayed_work *dwork)
3180	{
3181	local_irq_disable();
3182	if (del_timer_sync(&dwork->timer))
3183	__queue_work(dwork->cpu, dwork->wq, &dwork->work);
3184	local_irq_enable();
3185	return flush_work(&dwork->work);
3186	}
3187	EXPORT_SYMBOL(flush_delayed_work);
3188
3189	/**
3190	* flush_rcu_work - wait for a rwork to finish executing the last queueing
3191	* @rwork: the rcu work to flush
3192	*
3193	* Return:
3194	* %true if flush_rcu_work() waited for the work to finish execution,
3195	* %false if it was already idle.
3196	*/
3197	bool flush_rcu_work(struct rcu_work *rwork)
3198	{
3199	if (test_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&rwork->work))) {
3200	rcu_barrier();
3201	flush_work(&rwork->work);
3202	return true;
3203	} else {
3204	return flush_work(&rwork->work);
3205	}
3206	}
3207	EXPORT_SYMBOL(flush_rcu_work);
3208
3209	static bool __cancel_work(struct work_struct *work, bool is_dwork)
3210	{
3211	unsigned long flags;
3212	int ret;
3213
3214	do {
3215	ret = try_to_grab_pending(work, is_dwork, &flags);
3216	} while (unlikely(ret == -EAGAIN));
3217
3218	if (unlikely(ret < 0))
3219	return false;
3220
3221	set_work_pool_and_clear_pending(work, get_work_pool_id(work));
3222	local_irq_restore(flags);
3223	return ret;
3224	}
3225
3226	/**
3227	* cancel_delayed_work - cancel a delayed work
3228	* @dwork: delayed_work to cancel
3229	*
3230	* Kill off a pending delayed_work.
3231	*
3232	* Return: %true if @dwork was pending and canceled; %false if it wasn't
3233	* pending.
3234	*
3235	* Note:
3236	* The work callback function may still be running on return, unless
3237	* it returns %true and the work doesn't re-arm itself. Explicitly flush or
3238	* use cancel_delayed_work_sync() to wait on it.
3239	*
3240	* This function is safe to call from any context including IRQ handler.
3241	*/
3242	bool cancel_delayed_work(struct delayed_work *dwork)
3243	{
3244	return __cancel_work(&dwork->work, true);
3245	}
3246	EXPORT_SYMBOL(cancel_delayed_work);
3247
3248	/**
3249	* cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
3250	* @dwork: the delayed work cancel
3251	*
3252	* This is cancel_work_sync() for delayed works.
3253	*
3254	* Return:
3255	* %true if @dwork was pending, %false otherwise.
3256	*/
3257	bool cancel_delayed_work_sync(struct delayed_work *dwork)
3258	{
3259	return __cancel_work_timer(&dwork->work, true);
3260	}
3261	EXPORT_SYMBOL(cancel_delayed_work_sync);
3262
3263	/**
3264	* schedule_on_each_cpu - execute a function synchronously on each online CPU
3265	* @func: the function to call
3266	*
3267	* schedule_on_each_cpu() executes @func on each online CPU using the
3268	* system workqueue and blocks until all CPUs have completed.
3269	* schedule_on_each_cpu() is very slow.
3270	*
3271	* Return:
3272	* 0 on success, -errno on failure.
3273	*/
3274	int schedule_on_each_cpu(work_func_t func)
3275	{
3276	int cpu;
3277	struct work_struct __percpu *works;
3278
3279	works = alloc_percpu(struct work_struct);
3280	if (!works)
3281	return -ENOMEM;
3282
3283	get_online_cpus();
3284
3285	for_each_online_cpu(cpu) {
3286	struct work_struct *work = per_cpu_ptr(works, cpu);
3287
3288	INIT_WORK(work, func);
3289	schedule_work_on(cpu, work);
3290	}
3291
3292	for_each_online_cpu(cpu)
3293	flush_work(per_cpu_ptr(works, cpu));
3294
3295	put_online_cpus();
3296	free_percpu(works);
3297	return 0;
3298	}
3299
3300	/**
3301	* execute_in_process_context - reliably execute the routine with user context
3302	* @fn: the function to execute
3303	* @ew: guaranteed storage for the execute work structure (must
3304	* be available when the work executes)
3305	*
3306	* Executes the function immediately if process context is available,
3307	* otherwise schedules the function for delayed execution.
3308	*
3309	* Return: 0 - function was executed
3310	* 1 - function was scheduled for execution
3311	*/
3312	int execute_in_process_context(work_func_t fn, struct execute_work *ew)
3313	{
3314	if (!in_interrupt()) {
3315	fn(&ew->work);
3316	return 0;
3317	}
3318
3319	INIT_WORK(&ew->work, fn);
3320	schedule_work(&ew->work);
3321
3322	return 1;
3323	}
3324	EXPORT_SYMBOL_GPL(execute_in_process_context);
3325
3326	/**
3327	* free_workqueue_attrs - free a workqueue_attrs
3328	* @attrs: workqueue_attrs to free
3329	*
3330	* Undo alloc_workqueue_attrs().
3331	*/
3332	static void free_workqueue_attrs(struct workqueue_attrs *attrs)
3333	{
3334	if (attrs) {
3335	free_cpumask_var(attrs->cpumask);
3336	kfree(attrs);
3337	}
3338	}
3339
3340	/**
3341	* alloc_workqueue_attrs - allocate a workqueue_attrs
3342	*
3343	* Allocate a new workqueue_attrs, initialize with default settings and
3344	* return it.
3345	*
3346	* Return: The allocated new workqueue_attr on success. %NULL on failure.
3347	*/
3348	static struct workqueue_attrs *alloc_workqueue_attrs(void)
3349	{
3350	struct workqueue_attrs *attrs;
3351
3352	attrs = kzalloc(sizeof(*attrs), GFP_KERNEL);
3353	if (!attrs)
3354	goto fail;
3355	if (!alloc_cpumask_var(&attrs->cpumask, GFP_KERNEL))
3356	goto fail;
3357
3358	cpumask_copy(attrs->cpumask, cpu_possible_mask);
3359	return attrs;
3360	fail:
3361	free_workqueue_attrs(attrs);
3362	return NULL;
3363	}
3364
3365	static void copy_workqueue_attrs(struct workqueue_attrs *to,
3366	const struct workqueue_attrs *from)
3367	{
3368	to->nice = from->nice;
3369	cpumask_copy(to->cpumask, from->cpumask);
3370	/*
3371	* Unlike hash and equality test, this function doesn't ignore
3372	* ->no_numa as it is used for both pool and wq attrs. Instead,
3373	* get_unbound_pool() explicitly clears ->no_numa after copying.
3374	*/
3375	to->no_numa = from->no_numa;
3376	}
3377
3378	/* hash value of the content of @attr */
3379	static u32 wqattrs_hash(const struct workqueue_attrs *attrs)
3380	{
3381	u32 hash = 0;
3382
3383	hash = jhash_1word(attrs->nice, hash);
3384	hash = jhash(cpumask_bits(attrs->cpumask),
3385	BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash);
3386	return hash;
3387	}
3388
3389	/* content equality test */
3390	static bool wqattrs_equal(const struct workqueue_attrs *a,
3391	const struct workqueue_attrs *b)
3392	{
3393	if (a->nice != b->nice)
3394	return false;
3395	if (!cpumask_equal(a->cpumask, b->cpumask))
3396	return false;
3397	return true;
3398	}
3399
3400	/**
3401	* init_worker_pool - initialize a newly zalloc'd worker_pool
3402	* @pool: worker_pool to initialize
3403	*
3404	* Initialize a newly zalloc'd @pool. It also allocates @pool->attrs.
3405	*
3406	* Return: 0 on success, -errno on failure. Even on failure, all fields
3407	* inside @pool proper are initialized and put_unbound_pool() can be called
3408	* on @pool safely to release it.
3409	*/
3410	static int init_worker_pool(struct worker_pool *pool)
3411	{
3412	spin_lock_init(&pool->lock);
3413	pool->id = -1;
3414	pool->cpu = -1;
3415	pool->node = NUMA_NO_NODE;
3416	pool->flags \|= POOL_DISASSOCIATED;
3417	pool->watchdog_ts = jiffies;
3418	INIT_LIST_HEAD(&pool->worklist);
3419	INIT_LIST_HEAD(&pool->idle_list);
3420	hash_init(pool->busy_hash);
3421
3422	timer_setup(&pool->idle_timer, idle_worker_timeout, TIMER_DEFERRABLE);
3423
3424	timer_setup(&pool->mayday_timer, pool_mayday_timeout, 0);
3425
3426	INIT_LIST_HEAD(&pool->workers);
3427
3428	ida_init(&pool->worker_ida);
3429	INIT_HLIST_NODE(&pool->hash_node);
3430	pool->refcnt = 1;
3431
3432	/* shouldn't fail above this point */
3433	pool->attrs = alloc_workqueue_attrs();
3434	if (!pool->attrs)
3435	return -ENOMEM;
3436	return 0;
3437	}
3438
3439	#ifdef CONFIG_LOCKDEP
3440	static void wq_init_lockdep(struct workqueue_struct *wq)
3441	{
3442	char *lock_name;
3443
3444	lockdep_register_key(&wq->key);
3445	lock_name = kasprintf(GFP_KERNEL, "%s%s", "(wq_completion)", wq->name);
3446	if (!lock_name)
3447	lock_name = wq->name;
3448
3449	wq->lock_name = lock_name;
3450	lockdep_init_map(&wq->lockdep_map, lock_name, &wq->key, 0);
3451	}
3452
3453	static void wq_unregister_lockdep(struct workqueue_struct *wq)
3454	{
3455	lockdep_unregister_key(&wq->key);
3456	}
3457
3458	static void wq_free_lockdep(struct workqueue_struct *wq)
3459	{
3460	if (wq->lock_name != wq->name)
3461	kfree(wq->lock_name);
3462	}
3463	#else
3464	static void wq_init_lockdep(struct workqueue_struct *wq)
3465	{
3466	}
3467
3468	static void wq_unregister_lockdep(struct workqueue_struct *wq)
3469	{
3470	}
3471
3472	static void wq_free_lockdep(struct workqueue_struct *wq)
3473	{
3474	}
3475	#endif
3476
3477	static void rcu_free_wq(struct rcu_head *rcu)
3478	{
3479	struct workqueue_struct *wq =
3480	container_of(rcu, struct workqueue_struct, rcu);
3481
3482	wq_free_lockdep(wq);
3483
3484	if (!(wq->flags & WQ_UNBOUND))
3485	free_percpu(wq->cpu_pwqs);
3486	else
3487	free_workqueue_attrs(wq->unbound_attrs);
3488
3489	kfree(wq->rescuer);
3490	kfree(wq);
3491	}
3492
3493	static void rcu_free_pool(struct rcu_head *rcu)
3494	{
3495	struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu);
3496
3497	ida_destroy(&pool->worker_ida);
3498	free_workqueue_attrs(pool->attrs);
3499	kfree(pool);
3500	}
3501
3502	/**
3503	* put_unbound_pool - put a worker_pool
3504	* @pool: worker_pool to put
3505	*
3506	* Put @pool. If its refcnt reaches zero, it gets destroyed in RCU
3507	* safe manner. get_unbound_pool() calls this function on its failure path
3508	* and this function should be able to release pools which went through,
3509	* successfully or not, init_worker_pool().
3510	*
3511	* Should be called with wq_pool_mutex held.
3512	*/
3513	static void put_unbound_pool(struct worker_pool *pool)
3514	{
3515	DECLARE_COMPLETION_ONSTACK(detach_completion);
3516	struct worker *worker;
3517
3518	lockdep_assert_held(&wq_pool_mutex);
3519
3520	if (--pool->refcnt)
3521	return;
3522
3523	/* sanity checks */
3524	if (WARN_ON(!(pool->cpu < 0)) \|\|
3525	WARN_ON(!list_empty(&pool->worklist)))
3526	return;
3527
3528	/* release id and unhash */
3529	if (pool->id >= 0)
3530	idr_remove(&worker_pool_idr, pool->id);
3531	hash_del(&pool->hash_node);
3532
3533	/*
3534	* Become the manager and destroy all workers. This prevents
3535	* @pool's workers from blocking on attach_mutex. We're the last
3536	* manager and @pool gets freed with the flag set.
3537	*/
3538	spin_lock_irq(&pool->lock);
3539	wait_event_lock_irq(wq_manager_wait,
3540	!(pool->flags & POOL_MANAGER_ACTIVE), pool->lock);
3541	pool->flags \|= POOL_MANAGER_ACTIVE;
3542
3543	while ((worker = first_idle_worker(pool)))
3544	destroy_worker(worker);
3545	WARN_ON(pool->nr_workers \|\| pool->nr_idle);
3546	spin_unlock_irq(&pool->lock);
3547
3548	mutex_lock(&wq_pool_attach_mutex);
3549	if (!list_empty(&pool->workers))
3550	pool->detach_completion = &detach_completion;
3551	mutex_unlock(&wq_pool_attach_mutex);
3552
3553	if (pool->detach_completion)
3554	wait_for_completion(pool->detach_completion);
3555
3556	/* shut down the timers */
3557	del_timer_sync(&pool->idle_timer);
3558	del_timer_sync(&pool->mayday_timer);
3559
3560	/* RCU protected to allow dereferences from get_work_pool() */
3561	call_rcu(&pool->rcu, rcu_free_pool);
3562	}
3563
3564	/**
3565	* get_unbound_pool - get a worker_pool with the specified attributes
3566	* @attrs: the attributes of the worker_pool to get
3567	*
3568	* Obtain a worker_pool which has the same attributes as @attrs, bump the
3569	* reference count and return it. If there already is a matching
3570	* worker_pool, it will be used; otherwise, this function attempts to
3571	* create a new one.
3572	*
3573	* Should be called with wq_pool_mutex held.
3574	*
3575	* Return: On success, a worker_pool with the same attributes as @attrs.
3576	* On failure, %NULL.
3577	*/
3578	static struct worker_pool get_unbound_pool(const struct workqueue_attrs attrs)
3579	{
3580	u32 hash = wqattrs_hash(attrs);
3581	struct worker_pool *pool;
3582	int node;
3583	int target_node = NUMA_NO_NODE;
3584
3585	lockdep_assert_held(&wq_pool_mutex);
3586
3587	/* do we already have a matching pool? */
3588	hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) {
3589	if (wqattrs_equal(pool->attrs, attrs)) {
3590	pool->refcnt++;
3591	return pool;
3592	}
3593	}
3594
3595	/* if cpumask is contained inside a NUMA node, we belong to that node */
3596	if (wq_numa_enabled) {
3597	for_each_node(node) {
3598	if (cpumask_subset(attrs->cpumask,
3599	wq_numa_possible_cpumask[node])) {
3600	target_node = node;
3601	break;
3602	}
3603	}
3604	}
3605
3606	/* nope, create a new one */
3607	pool = kzalloc_node(sizeof(*pool), GFP_KERNEL, target_node);
3608	if (!pool \|\| init_worker_pool(pool) < 0)
3609	goto fail;
3610
3611	lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */
3612	copy_workqueue_attrs(pool->attrs, attrs);
3613	pool->node = target_node;
3614
3615	/*
3616	* no_numa isn't a worker_pool attribute, always clear it. See
3617	* 'struct workqueue_attrs' comments for detail.
3618	*/
3619	pool->attrs->no_numa = false;
3620
3621	if (worker_pool_assign_id(pool) < 0)
3622	goto fail;
3623
3624	/* create and start the initial worker */
3625	if (wq_online && !create_worker(pool))
3626	goto fail;
3627
3628	/* install */
3629	hash_add(unbound_pool_hash, &pool->hash_node, hash);
3630
3631	return pool;
3632	fail:
3633	if (pool)
3634	put_unbound_pool(pool);
3635	return NULL;
3636	}
3637
3638	static void rcu_free_pwq(struct rcu_head *rcu)
3639	{
3640	kmem_cache_free(pwq_cache,
3641	container_of(rcu, struct pool_workqueue, rcu));
3642	}
3643
3644	/*
3645	* Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt
3646	* and needs to be destroyed.
3647	*/
3648	static void pwq_unbound_release_workfn(struct work_struct *work)
3649	{
3650	struct pool_workqueue *pwq = container_of(work, struct pool_workqueue,
3651	unbound_release_work);
3652	struct workqueue_struct *wq = pwq->wq;
3653	struct worker_pool *pool = pwq->pool;
3654	bool is_last;
3655
3656	if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND)))
3657	return;
3658
3659	mutex_lock(&wq->mutex);
3660	list_del_rcu(&pwq->pwqs_node);
3661	is_last = list_empty(&wq->pwqs);
3662	mutex_unlock(&wq->mutex);
3663
3664	mutex_lock(&wq_pool_mutex);
3665	put_unbound_pool(pool);
3666	mutex_unlock(&wq_pool_mutex);
3667
3668	call_rcu(&pwq->rcu, rcu_free_pwq);
3669
3670	/*
3671	* If we're the last pwq going away, @wq is already dead and no one
3672	* is gonna access it anymore. Schedule RCU free.
3673	*/
3674	if (is_last) {
3675	wq_unregister_lockdep(wq);
3676	call_rcu(&wq->rcu, rcu_free_wq);
3677	}
3678	}
3679
3680	/**
3681	* pwq_adjust_max_active - update a pwq's max_active to the current setting
3682	* @pwq: target pool_workqueue
3683	*
3684	* If @pwq isn't freezing, set @pwq->max_active to the associated
3685	* workqueue's saved_max_active and activate delayed work items
3686	* accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
3687	*/
3688	static void pwq_adjust_max_active(struct pool_workqueue *pwq)
3689	{
3690	struct workqueue_struct *wq = pwq->wq;
3691	bool freezable = wq->flags & WQ_FREEZABLE;
3692	unsigned long flags;
3693
3694	/* for @wq->saved_max_active */
3695	lockdep_assert_held(&wq->mutex);
3696
3697	/* fast exit for non-freezable wqs */
3698	if (!freezable && pwq->max_active == wq->saved_max_active)
3699	return;
3700
3701	/* this function can be called during early boot w/ irq disabled */
3702	spin_lock_irqsave(&pwq->pool->lock, flags);
3703
3704	/*
3705	* During [un]freezing, the caller is responsible for ensuring that
3706	* this function is called at least once after @workqueue_freezing
3707	* is updated and visible.
3708	*/
3709	if (!freezable \|\| !workqueue_freezing) {
3710	pwq->max_active = wq->saved_max_active;
3711
3712	while (!list_empty(&pwq->delayed_works) &&
3713	pwq->nr_active < pwq->max_active)
3714	pwq_activate_first_delayed(pwq);
3715
3716	/*
3717	* Need to kick a worker after thawed or an unbound wq's
3718	* max_active is bumped. It's a slow path. Do it always.
3719	*/
3720	wake_up_worker(pwq->pool);
3721	} else {
3722	pwq->max_active = 0;
3723	}
3724
3725	spin_unlock_irqrestore(&pwq->pool->lock, flags);
3726	}
3727
3728	/* initialize newly alloced @pwq which is associated with @wq and @pool */
3729	static void init_pwq(struct pool_workqueue pwq, struct workqueue_struct wq,
3730	struct worker_pool *pool)
3731	{
3732	BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK);
3733
3734	memset(pwq, 0, sizeof(*pwq));
3735
3736	pwq->pool = pool;
3737	pwq->wq = wq;
3738	pwq->flush_color = -1;
3739	pwq->refcnt = 1;
3740	INIT_LIST_HEAD(&pwq->delayed_works);
3741	INIT_LIST_HEAD(&pwq->pwqs_node);
3742	INIT_LIST_HEAD(&pwq->mayday_node);
3743	INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn);
3744	}
3745
3746	/* sync @pwq with the current state of its associated wq and link it */
3747	static void link_pwq(struct pool_workqueue *pwq)
3748	{
3749	struct workqueue_struct *wq = pwq->wq;
3750
3751	lockdep_assert_held(&wq->mutex);
3752
3753	/* may be called multiple times, ignore if already linked */
3754	if (!list_empty(&pwq->pwqs_node))
3755	return;
3756
3757	/* set the matching work_color */
3758	pwq->work_color = wq->work_color;
3759
3760	/* sync max_active to the current setting */
3761	pwq_adjust_max_active(pwq);
3762
3763	/* link in @pwq */
3764	list_add_rcu(&pwq->pwqs_node, &wq->pwqs);
3765	}
3766
3767	/* obtain a pool matching @attr and create a pwq associating the pool and @wq */
3768	static struct pool_workqueue alloc_unbound_pwq(struct workqueue_struct wq,
3769	const struct workqueue_attrs *attrs)
3770	{
3771	struct worker_pool *pool;
3772	struct pool_workqueue *pwq;
3773
3774	lockdep_assert_held(&wq_pool_mutex);
3775
3776	pool = get_unbound_pool(attrs);
3777	if (!pool)
3778	return NULL;
3779
3780	pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node);
3781	if (!pwq) {
3782	put_unbound_pool(pool);
3783	return NULL;
3784	}
3785
3786	init_pwq(pwq, wq, pool);
3787	return pwq;
3788	}
3789
3790	/**
3791	* wq_calc_node_cpumask - calculate a wq_attrs' cpumask for the specified node
3792	* @attrs: the wq_attrs of the default pwq of the target workqueue
3793	* @node: the target NUMA node
3794	* @cpu_going_down: if >= 0, the CPU to consider as offline
3795	* @cpumask: outarg, the resulting cpumask
3796	*
3797	* Calculate the cpumask a workqueue with @attrs should use on @node. If
3798	* @cpu_going_down is >= 0, that cpu is considered offline during
3799	* calculation. The result is stored in @cpumask.
3800	*
3801	* If NUMA affinity is not enabled, @attrs->cpumask is always used. If
3802	* enabled and @node has online CPUs requested by @attrs, the returned
3803	* cpumask is the intersection of the possible CPUs of @node and
3804	* @attrs->cpumask.
3805	*
3806	* The caller is responsible for ensuring that the cpumask of @node stays
3807	* stable.
3808	*
3809	* Return: %true if the resulting @cpumask is different from @attrs->cpumask,
3810	* %false if equal.
3811	*/
3812	static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node,
3813	int cpu_going_down, cpumask_t *cpumask)
3814	{
3815	if (!wq_numa_enabled \|\| attrs->no_numa)
3816	goto use_dfl;
3817
3818	/* does @node have any online CPUs @attrs wants? */
3819	cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask);
3820	if (cpu_going_down >= 0)
3821	cpumask_clear_cpu(cpu_going_down, cpumask);
3822
3823	if (cpumask_empty(cpumask))
3824	goto use_dfl;
3825
3826	/* yeap, return possible CPUs in @node that @attrs wants */
3827	cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]);
3828
3829	if (cpumask_empty(cpumask)) {
3830	pr_warn_once("WARNING: workqueue cpumask: online intersect > "
3831	"possible intersect\n");
3832	return false;
3833	}
3834
3835	return !cpumask_equal(cpumask, attrs->cpumask);
3836
3837	use_dfl:
3838	cpumask_copy(cpumask, attrs->cpumask);
3839	return false;
3840	}
3841
3842	/* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
3843	static struct pool_workqueue numa_pwq_tbl_install(struct workqueue_struct wq,
3844	int node,
3845	struct pool_workqueue *pwq)
3846	{
3847	struct pool_workqueue *old_pwq;
3848
3849	lockdep_assert_held(&wq_pool_mutex);
3850	lockdep_assert_held(&wq->mutex);
3851
3852	/* link_pwq() can handle duplicate calls */
3853	link_pwq(pwq);
3854
3855	old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
3856	rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq);
3857	return old_pwq;
3858	}
3859
3860	/* context to store the prepared attrs & pwqs before applying */
3861	struct apply_wqattrs_ctx {
3862	struct workqueue_struct wq; / target workqueue */
3863	struct workqueue_attrs attrs; / attrs to apply */
3864	struct list_head list; /* queued for batching commit */
3865	struct pool_workqueue *dfl_pwq;
3866	struct pool_workqueue *pwq_tbl[];
3867	};
3868
3869	/* free the resources after success or abort */
3870	static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx *ctx)
3871	{
3872	if (ctx) {
3873	int node;
3874
3875	for_each_node(node)
3876	put_pwq_unlocked(ctx->pwq_tbl[node]);
3877	put_pwq_unlocked(ctx->dfl_pwq);
3878
3879	free_workqueue_attrs(ctx->attrs);
3880
3881	kfree(ctx);
3882	}
3883	}
3884
3885	/* allocate the attrs and pwqs for later installation */
3886	static struct apply_wqattrs_ctx *
3887	apply_wqattrs_prepare(struct workqueue_struct *wq,
3888	const struct workqueue_attrs *attrs)
3889	{
3890	struct apply_wqattrs_ctx *ctx;
3891	struct workqueue_attrs new_attrs, tmp_attrs;
3892	int node;
3893
3894	lockdep_assert_held(&wq_pool_mutex);
3895
3896	ctx = kzalloc(struct_size(ctx, pwq_tbl, nr_node_ids), GFP_KERNEL);
3897
3898	new_attrs = alloc_workqueue_attrs();
3899	tmp_attrs = alloc_workqueue_attrs();
3900	if (!ctx \|\| !new_attrs \|\| !tmp_attrs)
3901	goto out_free;
3902
3903	/*
3904	* Calculate the attrs of the default pwq.
3905	* If the user configured cpumask doesn't overlap with the
3906	* wq_unbound_cpumask, we fallback to the wq_unbound_cpumask.
3907	*/
3908	copy_workqueue_attrs(new_attrs, attrs);
3909	cpumask_and(new_attrs->cpumask, new_attrs->cpumask, wq_unbound_cpumask);
3910	if (unlikely(cpumask_empty(new_attrs->cpumask)))
3911	cpumask_copy(new_attrs->cpumask, wq_unbound_cpumask);
3912
3913	/*
3914	* We may create multiple pwqs with differing cpumasks. Make a
3915	* copy of @new_attrs which will be modified and used to obtain
3916	* pools.
3917	*/
3918	copy_workqueue_attrs(tmp_attrs, new_attrs);
3919
3920	/*
3921	* If something goes wrong during CPU up/down, we'll fall back to
3922	* the default pwq covering whole @attrs->cpumask. Always create
3923	* it even if we don't use it immediately.
3924	*/
3925	ctx->dfl_pwq = alloc_unbound_pwq(wq, new_attrs);
3926	if (!ctx->dfl_pwq)
3927	goto out_free;
3928
3929	for_each_node(node) {
3930	if (wq_calc_node_cpumask(new_attrs, node, -1, tmp_attrs->cpumask)) {
3931	ctx->pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs);
3932	if (!ctx->pwq_tbl[node])
3933	goto out_free;
3934	} else {
3935	ctx->dfl_pwq->refcnt++;
3936	ctx->pwq_tbl[node] = ctx->dfl_pwq;
3937	}
3938	}
3939
3940	/* save the user configured attrs and sanitize it. */
3941	copy_workqueue_attrs(new_attrs, attrs);
3942	cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask);
3943	ctx->attrs = new_attrs;
3944
3945	ctx->wq = wq;
3946	free_workqueue_attrs(tmp_attrs);
3947	return ctx;
3948
3949	out_free:
3950	free_workqueue_attrs(tmp_attrs);
3951	free_workqueue_attrs(new_attrs);
3952	apply_wqattrs_cleanup(ctx);
3953	return NULL;
3954	}
3955
3956	/* set attrs and install prepared pwqs, @ctx points to old pwqs on return */
3957	static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx)
3958	{
3959	int node;
3960
3961	/* all pwqs have been created successfully, let's install'em */
3962	mutex_lock(&ctx->wq->mutex);
3963
3964	copy_workqueue_attrs(ctx->wq->unbound_attrs, ctx->attrs);
3965
3966	/* save the previous pwq and install the new one */
3967	for_each_node(node)
3968	ctx->pwq_tbl[node] = numa_pwq_tbl_install(ctx->wq, node,
3969	ctx->pwq_tbl[node]);
3970
3971	/* @dfl_pwq might not have been used, ensure it's linked */
3972	link_pwq(ctx->dfl_pwq);
3973	swap(ctx->wq->dfl_pwq, ctx->dfl_pwq);
3974
3975	mutex_unlock(&ctx->wq->mutex);
3976	}
3977
3978	static void apply_wqattrs_lock(void)
3979	{
3980	/* CPUs should stay stable across pwq creations and installations */
3981	get_online_cpus();
3982	mutex_lock(&wq_pool_mutex);
3983	}
3984
3985	static void apply_wqattrs_unlock(void)
3986	{
3987	mutex_unlock(&wq_pool_mutex);
3988	put_online_cpus();
3989	}
3990
3991	static int apply_workqueue_attrs_locked(struct workqueue_struct *wq,
3992	const struct workqueue_attrs *attrs)
3993	{
3994	struct apply_wqattrs_ctx *ctx;
3995
3996	/* only unbound workqueues can change attributes */
3997	if (WARN_ON(!(wq->flags & WQ_UNBOUND)))
3998	return -EINVAL;
3999
4000	/* creating multiple pwqs breaks ordering guarantee */
4001	if (!list_empty(&wq->pwqs)) {
4002	if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT))
4003	return -EINVAL;
4004
4005	wq->flags &= ~__WQ_ORDERED;
4006	}
4007
4008	ctx = apply_wqattrs_prepare(wq, attrs);
4009	if (!ctx)
4010	return -ENOMEM;
4011
4012	/* the ctx has been prepared successfully, let's commit it */
4013	apply_wqattrs_commit(ctx);
4014	apply_wqattrs_cleanup(ctx);
4015
4016	return 0;
4017	}
4018
4019	/**
4020	* apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
4021	* @wq: the target workqueue
4022	* @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
4023	*
4024	* Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
4025	* machines, this function maps a separate pwq to each NUMA node with
4026	* possibles CPUs in @attrs->cpumask so that work items are affine to the
4027	* NUMA node it was issued on. Older pwqs are released as in-flight work
4028	* items finish. Note that a work item which repeatedly requeues itself
4029	* back-to-back will stay on its current pwq.
4030	*
4031	* Performs GFP_KERNEL allocations.
4032	*
4033	* Return: 0 on success and -errno on failure.
4034	*/
4035	static int apply_workqueue_attrs(struct workqueue_struct *wq,
4036	const struct workqueue_attrs *attrs)
4037	{
4038	int ret;
4039
4040	apply_wqattrs_lock();
4041	ret = apply_workqueue_attrs_locked(wq, attrs);
4042	apply_wqattrs_unlock();
4043
4044	return ret;
4045	}
4046
4047	/**
4048	* wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
4049	* @wq: the target workqueue
4050	* @cpu: the CPU coming up or going down
4051	* @online: whether @cpu is coming up or going down
4052	*
4053	* This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
4054	* %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
4055	* @wq accordingly.
4056	*
4057	* If NUMA affinity can't be adjusted due to memory allocation failure, it
4058	* falls back to @wq->dfl_pwq which may not be optimal but is always
4059	* correct.
4060	*
4061	* Note that when the last allowed CPU of a NUMA node goes offline for a
4062	* workqueue with a cpumask spanning multiple nodes, the workers which were
4063	* already executing the work items for the workqueue will lose their CPU
4064	* affinity and may execute on any CPU. This is similar to how per-cpu
4065	* workqueues behave on CPU_DOWN. If a workqueue user wants strict
4066	* affinity, it's the user's responsibility to flush the work item from
4067	* CPU_DOWN_PREPARE.
4068	*/
4069	static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu,
4070	bool online)
4071	{
4072	int node = cpu_to_node(cpu);
4073	int cpu_off = online ? -1 : cpu;
4074	struct pool_workqueue old_pwq = NULL, pwq;
4075	struct workqueue_attrs *target_attrs;
4076	cpumask_t *cpumask;
4077
4078	lockdep_assert_held(&wq_pool_mutex);
4079
4080	if (!wq_numa_enabled \|\| !(wq->flags & WQ_UNBOUND) \|\|
4081	wq->unbound_attrs->no_numa)
4082	return;
4083
4084	/*
4085	* We don't wanna alloc/free wq_attrs for each wq for each CPU.
4086	* Let's use a preallocated one. The following buf is protected by
4087	* CPU hotplug exclusion.
4088	*/
4089	target_attrs = wq_update_unbound_numa_attrs_buf;
4090	cpumask = target_attrs->cpumask;
4091
4092	copy_workqueue_attrs(target_attrs, wq->unbound_attrs);
4093	pwq = unbound_pwq_by_node(wq, node);
4094
4095	/*
4096	* Let's determine what needs to be done. If the target cpumask is
4097	* different from the default pwq's, we need to compare it to @pwq's
4098	* and create a new one if they don't match. If the target cpumask
4099	* equals the default pwq's, the default pwq should be used.
4100	*/
4101	if (wq_calc_node_cpumask(wq->dfl_pwq->pool->attrs, node, cpu_off, cpumask)) {
4102	if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask))
4103	return;
4104	} else {
4105	goto use_dfl_pwq;
4106	}
4107
4108	/* create a new pwq */
4109	pwq = alloc_unbound_pwq(wq, target_attrs);
4110	if (!pwq) {
4111	pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
4112	wq->name);
4113	goto use_dfl_pwq;
4114	}
4115
4116	/* Install the new pwq. */
4117	mutex_lock(&wq->mutex);
4118	old_pwq = numa_pwq_tbl_install(wq, node, pwq);
4119	goto out_unlock;
4120
4121	use_dfl_pwq:
4122	mutex_lock(&wq->mutex);
4123	spin_lock_irq(&wq->dfl_pwq->pool->lock);
4124	get_pwq(wq->dfl_pwq);
4125	spin_unlock_irq(&wq->dfl_pwq->pool->lock);
4126	old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq);
4127	out_unlock:
4128	mutex_unlock(&wq->mutex);
4129	put_pwq_unlocked(old_pwq);
4130	}
4131
4132	static int alloc_and_link_pwqs(struct workqueue_struct *wq)
4133	{
4134	bool highpri = wq->flags & WQ_HIGHPRI;
4135	int cpu, ret;
4136
4137	if (!(wq->flags & WQ_UNBOUND)) {
4138	wq->cpu_pwqs = alloc_percpu(struct pool_workqueue);
4139	if (!wq->cpu_pwqs)
4140	return -ENOMEM;
4141
4142	for_each_possible_cpu(cpu) {
4143	struct pool_workqueue *pwq =
4144	per_cpu_ptr(wq->cpu_pwqs, cpu);
4145	struct worker_pool *cpu_pools =
4146	per_cpu(cpu_worker_pools, cpu);
4147
4148	init_pwq(pwq, wq, &cpu_pools[highpri]);
4149
4150	mutex_lock(&wq->mutex);
4151	link_pwq(pwq);
4152	mutex_unlock(&wq->mutex);
4153	}
4154	return 0;
4155	} else if (wq->flags & __WQ_ORDERED) {
4156	ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]);
4157	/* there should only be single pwq for ordering guarantee */
4158	WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node \|\|
4159	wq->pwqs.prev != &wq->dfl_pwq->pwqs_node),
4160	"ordering guarantee broken for workqueue %s\n", wq->name);
4161	return ret;
4162	} else {
4163	return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]);
4164	}
4165	}
4166
4167	static int wq_clamp_max_active(int max_active, unsigned int flags,
4168	const char *name)
4169	{
4170	int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE;
4171
4172	if (max_active < 1 \|\| max_active > lim)
4173	pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
4174	max_active, name, 1, lim);
4175
4176	return clamp_val(max_active, 1, lim);
4177	}
4178
4179	/*
4180	* Workqueues which may be used during memory reclaim should have a rescuer
4181	* to guarantee forward progress.
4182	*/
4183	static int init_rescuer(struct workqueue_struct *wq)
4184	{
4185	struct worker *rescuer;
4186	int ret;
4187
4188	if (!(wq->flags & WQ_MEM_RECLAIM))
4189	return 0;
4190
4191	rescuer = alloc_worker(NUMA_NO_NODE);
4192	if (!rescuer)
4193	return -ENOMEM;
4194
4195	rescuer->rescue_wq = wq;
4196	rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", wq->name);
4197	ret = PTR_ERR_OR_ZERO(rescuer->task);
4198	if (ret) {
4199	kfree(rescuer);
4200	return ret;
4201	}
4202
4203	wq->rescuer = rescuer;
4204	kthread_bind_mask(rescuer->task, cpu_possible_mask);
4205	wake_up_process(rescuer->task);
4206
4207	return 0;
4208	}
4209
4210	__printf(1, 4)
4211	struct workqueue_struct alloc_workqueue(const char fmt,
4212	unsigned int flags,
4213	int max_active, ...)
4214	{
4215	size_t tbl_size = 0;
4216	va_list args;
4217	struct workqueue_struct *wq;
4218	struct pool_workqueue *pwq;
4219
4220	/*
4221	* Unbound && max_active == 1 used to imply ordered, which is no
4222	* longer the case on NUMA machines due to per-node pools. While
4223	* alloc_ordered_workqueue() is the right way to create an ordered
4224	* workqueue, keep the previous behavior to avoid subtle breakages
4225	* on NUMA.
4226	*/
4227	if ((flags & WQ_UNBOUND) && max_active == 1)
4228	flags \|= __WQ_ORDERED;
4229
4230	/* see the comment above the definition of WQ_POWER_EFFICIENT */
4231	if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient)
4232	flags \|= WQ_UNBOUND;
4233
4234	/* allocate wq and format name */
4235	if (flags & WQ_UNBOUND)
4236	tbl_size = nr_node_ids * sizeof(wq->numa_pwq_tbl[0]);
4237
4238	wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL);
4239	if (!wq)
4240	return NULL;
4241
4242	if (flags & WQ_UNBOUND) {
4243	wq->unbound_attrs = alloc_workqueue_attrs();
4244	if (!wq->unbound_attrs)
4245	goto err_free_wq;
4246	}
4247
4248	va_start(args, max_active);
4249	vsnprintf(wq->name, sizeof(wq->name), fmt, args);
4250	va_end(args);
4251
4252	max_active = max_active ?: WQ_DFL_ACTIVE;
4253	max_active = wq_clamp_max_active(max_active, flags, wq->name);
4254
4255	/* init wq */
4256	wq->flags = flags;
4257	wq->saved_max_active = max_active;
4258	mutex_init(&wq->mutex);
4259	atomic_set(&wq->nr_pwqs_to_flush, 0);
4260	INIT_LIST_HEAD(&wq->pwqs);
4261	INIT_LIST_HEAD(&wq->flusher_queue);
4262	INIT_LIST_HEAD(&wq->flusher_overflow);
4263	INIT_LIST_HEAD(&wq->maydays);
4264
4265	wq_init_lockdep(wq);
4266	INIT_LIST_HEAD(&wq->list);
4267
4268	if (alloc_and_link_pwqs(wq) < 0)
4269	goto err_unreg_lockdep;
4270
4271	if (wq_online && init_rescuer(wq) < 0)
4272	goto err_destroy;
4273
4274	if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq))
4275	goto err_destroy;
4276
4277	/*
4278	* wq_pool_mutex protects global freeze state and workqueues list.
4279	* Grab it, adjust max_active and add the new @wq to workqueues
4280	* list.
4281	*/
4282	mutex_lock(&wq_pool_mutex);
4283
4284	mutex_lock(&wq->mutex);
4285	for_each_pwq(pwq, wq)
4286	pwq_adjust_max_active(pwq);
4287	mutex_unlock(&wq->mutex);
4288
4289	list_add_tail_rcu(&wq->list, &workqueues);
4290
4291	mutex_unlock(&wq_pool_mutex);
4292
4293	return wq;
4294
4295	err_unreg_lockdep:
4296	wq_unregister_lockdep(wq);
4297	wq_free_lockdep(wq);
4298	err_free_wq:
4299	free_workqueue_attrs(wq->unbound_attrs);
4300	kfree(wq);
4301	return NULL;
4302	err_destroy:
4303	destroy_workqueue(wq);
4304	return NULL;
4305	}
4306	EXPORT_SYMBOL_GPL(alloc_workqueue);
4307
4308	/**
4309	* destroy_workqueue - safely terminate a workqueue
4310	* @wq: target workqueue
4311	*
4312	* Safely destroy a workqueue. All work currently pending will be done first.
4313	*/
4314	void destroy_workqueue(struct workqueue_struct *wq)
4315	{
4316	struct pool_workqueue *pwq;
4317	int node;
4318
4319	/* drain it before proceeding with destruction */
4320	drain_workqueue(wq);
4321
4322	/* sanity checks */
4323	mutex_lock(&wq->mutex);
4324	for_each_pwq(pwq, wq) {
4325	int i;
4326
4327	for (i = 0; i < WORK_NR_COLORS; i++) {
4328	if (WARN_ON(pwq->nr_in_flight[i])) {
4329	mutex_unlock(&wq->mutex);
4330	show_workqueue_state();
4331	return;
4332	}
4333	}
4334
4335	if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) \|\|
4336	WARN_ON(pwq->nr_active) \|\|
4337	WARN_ON(!list_empty(&pwq->delayed_works))) {
4338	mutex_unlock(&wq->mutex);
4339	show_workqueue_state();
4340	return;
4341	}
4342	}
4343	mutex_unlock(&wq->mutex);
4344
4345	/*
4346	* wq list is used to freeze wq, remove from list after
4347	* flushing is complete in case freeze races us.
4348	*/
4349	mutex_lock(&wq_pool_mutex);
4350	list_del_rcu(&wq->list);
4351	mutex_unlock(&wq_pool_mutex);
4352
4353	workqueue_sysfs_unregister(wq);
4354
4355	if (wq->rescuer)
4356	kthread_stop(wq->rescuer->task);
4357
4358	if (!(wq->flags & WQ_UNBOUND)) {
4359	wq_unregister_lockdep(wq);
4360	/*
4361	* The base ref is never dropped on per-cpu pwqs. Directly
4362	* schedule RCU free.
4363	*/
4364	call_rcu(&wq->rcu, rcu_free_wq);
4365	} else {
4366	/*
4367	* We're the sole accessor of @wq at this point. Directly
4368	* access numa_pwq_tbl[] and dfl_pwq to put the base refs.
4369	* @wq will be freed when the last pwq is released.
4370	*/
4371	for_each_node(node) {
4372	pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]);
4373	RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL);
4374	put_pwq_unlocked(pwq);
4375	}
4376
4377	/*
4378	* Put dfl_pwq. @wq may be freed any time after dfl_pwq is
4379	* put. Don't access it afterwards.
4380	*/
4381	pwq = wq->dfl_pwq;
4382	wq->dfl_pwq = NULL;
4383	put_pwq_unlocked(pwq);
4384	}
4385	}
4386	EXPORT_SYMBOL_GPL(destroy_workqueue);
4387
4388	/**
4389	* workqueue_set_max_active - adjust max_active of a workqueue
4390	* @wq: target workqueue
4391	* @max_active: new max_active value.
4392	*
4393	* Set max_active of @wq to @max_active.
4394	*
4395	* CONTEXT:
4396	* Don't call from IRQ context.
4397	*/
4398	void workqueue_set_max_active(struct workqueue_struct *wq, int max_active)
4399	{
4400	struct pool_workqueue *pwq;
4401
4402	/* disallow meddling with max_active for ordered workqueues */
4403	if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT))
4404	return;
4405
4406	max_active = wq_clamp_max_active(max_active, wq->flags, wq->name);
4407
4408	mutex_lock(&wq->mutex);
4409
4410	wq->flags &= ~__WQ_ORDERED;
4411	wq->saved_max_active = max_active;
4412
4413	for_each_pwq(pwq, wq)
4414	pwq_adjust_max_active(pwq);
4415
4416	mutex_unlock(&wq->mutex);
4417	}
4418	EXPORT_SYMBOL_GPL(workqueue_set_max_active);
4419
4420	/**
4421	* current_work - retrieve %current task's work struct
4422	*
4423	* Determine if %current task is a workqueue worker and what it's working on.
4424	* Useful to find out the context that the %current task is running in.
4425	*
4426	* Return: work struct if %current task is a workqueue worker, %NULL otherwise.
4427	*/
4428	struct work_struct *current_work(void)
4429	{
4430	struct worker *worker = current_wq_worker();
4431
4432	return worker ? worker->current_work : NULL;
4433	}
4434	EXPORT_SYMBOL(current_work);
4435
4436	/**
4437	* current_is_workqueue_rescuer - is %current workqueue rescuer?
4438	*
4439	* Determine whether %current is a workqueue rescuer. Can be used from
4440	* work functions to determine whether it's being run off the rescuer task.
4441	*
4442	* Return: %true if %current is a workqueue rescuer. %false otherwise.
4443	*/
4444	bool current_is_workqueue_rescuer(void)
4445	{
4446	struct worker *worker = current_wq_worker();
4447
4448	return worker && worker->rescue_wq;
4449	}
4450
4451	/**
4452	* workqueue_congested - test whether a workqueue is congested
4453	* @cpu: CPU in question
4454	* @wq: target workqueue
4455	*
4456	* Test whether @wq's cpu workqueue for @cpu is congested. There is
4457	* no synchronization around this function and the test result is
4458	* unreliable and only useful as advisory hints or for debugging.
4459	*
4460	* If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU.
4461	* Note that both per-cpu and unbound workqueues may be associated with
4462	* multiple pool_workqueues which have separate congested states. A
4463	* workqueue being congested on one CPU doesn't mean the workqueue is also
4464	* contested on other CPUs / NUMA nodes.
4465	*
4466	* Return:
4467	* %true if congested, %false otherwise.
4468	*/
4469	bool workqueue_congested(int cpu, struct workqueue_struct *wq)
4470	{
4471	struct pool_workqueue *pwq;
4472	bool ret;
4473
4474	rcu_read_lock();
4475	preempt_disable();
4476
4477	if (cpu == WORK_CPU_UNBOUND)
4478	cpu = smp_processor_id();
4479
4480	if (!(wq->flags & WQ_UNBOUND))
4481	pwq = per_cpu_ptr(wq->cpu_pwqs, cpu);
4482	else
4483	pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu));
4484
4485	ret = !list_empty(&pwq->delayed_works);
4486	preempt_enable();
4487	rcu_read_unlock();
4488
4489	return ret;
4490	}
4491	EXPORT_SYMBOL_GPL(workqueue_congested);
4492
4493	/**
4494	* work_busy - test whether a work is currently pending or running
4495	* @work: the work to be tested
4496	*
4497	* Test whether @work is currently pending or running. There is no
4498	* synchronization around this function and the test result is
4499	* unreliable and only useful as advisory hints or for debugging.
4500	*
4501	* Return:
4502	* OR'd bitmask of WORK_BUSY_* bits.
4503	*/
4504	unsigned int work_busy(struct work_struct *work)
4505	{
4506	struct worker_pool *pool;
4507	unsigned long flags;
4508	unsigned int ret = 0;
4509
4510	if (work_pending(work))
4511	ret \|= WORK_BUSY_PENDING;
4512
4513	rcu_read_lock();
4514	pool = get_work_pool(work);
4515	if (pool) {
4516	spin_lock_irqsave(&pool->lock, flags);
4517	if (find_worker_executing_work(pool, work))
4518	ret \|= WORK_BUSY_RUNNING;
4519	spin_unlock_irqrestore(&pool->lock, flags);
4520	}
4521	rcu_read_unlock();
4522
4523	return ret;
4524	}
4525	EXPORT_SYMBOL_GPL(work_busy);
4526
4527	/**
4528	* set_worker_desc - set description for the current work item
4529	* @fmt: printf-style format string
4530	* @...: arguments for the format string
4531	*
4532	* This function can be called by a running work function to describe what
4533	* the work item is about. If the worker task gets dumped, this
4534	* information will be printed out together to help debugging. The
4535	* description can be at most WORKER_DESC_LEN including the trailing '\0'.
4536	*/
4537	void set_worker_desc(const char *fmt, ...)
4538	{
4539	struct worker *worker = current_wq_worker();
4540	va_list args;
4541
4542	if (worker) {
4543	va_start(args, fmt);
4544	vsnprintf(worker->desc, sizeof(worker->desc), fmt, args);
4545	va_end(args);
4546	}
4547	}
4548	EXPORT_SYMBOL_GPL(set_worker_desc);
4549
4550	/**
4551	* print_worker_info - print out worker information and description
4552	* @log_lvl: the log level to use when printing
4553	* @task: target task
4554	*
4555	* If @task is a worker and currently executing a work item, print out the
4556	* name of the workqueue being serviced and worker description set with
4557	* set_worker_desc() by the currently executing work item.
4558	*
4559	* This function can be safely called on any task as long as the
4560	* task_struct itself is accessible. While safe, this function isn't
4561	* synchronized and may print out mixups or garbages of limited length.
4562	*/
4563	void print_worker_info(const char log_lvl, struct task_struct task)
4564	{
4565	work_func_t *fn = NULL;
4566	char name[WQ_NAME_LEN] = { };
4567	char desc[WORKER_DESC_LEN] = { };
4568	struct pool_workqueue *pwq = NULL;
4569	struct workqueue_struct *wq = NULL;
4570	struct worker *worker;
4571
4572	if (!(task->flags & PF_WQ_WORKER))
4573	return;
4574
4575	/*
4576	* This function is called without any synchronization and @task
4577	* could be in any state. Be careful with dereferences.
4578	*/
4579	worker = kthread_probe_data(task);
4580
4581	/*
4582	* Carefully copy the associated workqueue's workfn, name and desc.
4583	* Keep the original last '\0' in case the original is garbage.
4584	*/
4585	probe_kernel_read(&fn, &worker->current_func, sizeof(fn));
4586	probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq));
4587	probe_kernel_read(&wq, &pwq->wq, sizeof(wq));
4588	probe_kernel_read(name, wq->name, sizeof(name) - 1);
4589	probe_kernel_read(desc, worker->desc, sizeof(desc) - 1);
4590
4591	if (fn \|\| name[0] \|\| desc[0]) {
4592	printk("%sWorkqueue: %s %ps", log_lvl, name, fn);
4593	if (strcmp(name, desc))
4594	pr_cont(" (%s)", desc);
4595	pr_cont("\n");
4596	}
4597	}
4598
4599	static void pr_cont_pool_info(struct worker_pool *pool)
4600	{
4601	pr_cont(" cpus=%*pbl", nr_cpumask_bits, pool->attrs->cpumask);
4602	if (pool->node != NUMA_NO_NODE)
4603	pr_cont(" node=%d", pool->node);
4604	pr_cont(" flags=0x%x nice=%d", pool->flags, pool->attrs->nice);
4605	}
4606
4607	static void pr_cont_work(bool comma, struct work_struct *work)
4608	{
4609	if (work->func == wq_barrier_func) {
4610	struct wq_barrier *barr;
4611
4612	barr = container_of(work, struct wq_barrier, work);
4613
4614	pr_cont("%s BAR(%d)", comma ? "," : "",
4615	task_pid_nr(barr->task));
4616	} else {
4617	pr_cont("%s %ps", comma ? "," : "", work->func);
4618	}
4619	}
4620
4621	static void show_pwq(struct pool_workqueue *pwq)
4622	{
4623	struct worker_pool *pool = pwq->pool;
4624	struct work_struct *work;
4625	struct worker *worker;
4626	bool has_in_flight = false, has_pending = false;
4627	int bkt;
4628
4629	pr_info(" pwq %d:", pool->id);
4630	pr_cont_pool_info(pool);
4631
4632	pr_cont(" active=%d/%d%s\n", pwq->nr_active, pwq->max_active,
4633	!list_empty(&pwq->mayday_node) ? " MAYDAY" : "");
4634
4635	hash_for_each(pool->busy_hash, bkt, worker, hentry) {
4636	if (worker->current_pwq == pwq) {
4637	has_in_flight = true;
4638	break;
4639	}
4640	}
4641	if (has_in_flight) {
4642	bool comma = false;
4643
4644	pr_info(" in-flight:");
4645	hash_for_each(pool->busy_hash, bkt, worker, hentry) {
4646	if (worker->current_pwq != pwq)
4647	continue;
4648
4649	pr_cont("%s %d%s:%ps", comma ? "," : "",
4650	task_pid_nr(worker->task),
4651	worker == pwq->wq->rescuer ? "(RESCUER)" : "",
4652	worker->current_func);
4653	list_for_each_entry(work, &worker->scheduled, entry)
4654	pr_cont_work(false, work);
4655	comma = true;
4656	}
4657	pr_cont("\n");
4658	}
4659
4660	list_for_each_entry(work, &pool->worklist, entry) {
4661	if (get_work_pwq(work) == pwq) {
4662	has_pending = true;
4663	break;
4664	}
4665	}
4666	if (has_pending) {
4667	bool comma = false;
4668
4669	pr_info(" pending:");
4670	list_for_each_entry(work, &pool->worklist, entry) {
4671	if (get_work_pwq(work) != pwq)
4672	continue;
4673
4674	pr_cont_work(comma, work);
4675	comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED);
4676	}
4677	pr_cont("\n");
4678	}
4679
4680	if (!list_empty(&pwq->delayed_works)) {
4681	bool comma = false;
4682
4683	pr_info(" delayed:");
4684	list_for_each_entry(work, &pwq->delayed_works, entry) {
4685	pr_cont_work(comma, work);
4686	comma = !(*work_data_bits(work) & WORK_STRUCT_LINKED);
4687	}
4688	pr_cont("\n");
4689	}
4690	}
4691
4692	/**
4693	* show_workqueue_state - dump workqueue state
4694	*
4695	* Called from a sysrq handler or try_to_freeze_tasks() and prints out
4696	* all busy workqueues and pools.
4697	*/
4698	void show_workqueue_state(void)
4699	{
4700	struct workqueue_struct *wq;
4701	struct worker_pool *pool;
4702	unsigned long flags;
4703	int pi;
4704
4705	rcu_read_lock();
4706
4707	pr_info("Showing busy workqueues and worker pools:\n");
4708
4709	list_for_each_entry_rcu(wq, &workqueues, list) {
4710	struct pool_workqueue *pwq;
4711	bool idle = true;
4712
4713	for_each_pwq(pwq, wq) {
4714	if (pwq->nr_active \|\| !list_empty(&pwq->delayed_works)) {
4715	idle = false;
4716	break;
4717	}
4718	}
4719	if (idle)
4720	continue;
4721
4722	pr_info("workqueue %s: flags=0x%x\n", wq->name, wq->flags);
4723
4724	for_each_pwq(pwq, wq) {
4725	spin_lock_irqsave(&pwq->pool->lock, flags);
4726	if (pwq->nr_active \|\| !list_empty(&pwq->delayed_works))
4727	show_pwq(pwq);
4728	spin_unlock_irqrestore(&pwq->pool->lock, flags);
4729	/*
4730	* We could be printing a lot from atomic context, e.g.
4731	* sysrq-t -> show_workqueue_state(). Avoid triggering
4732	* hard lockup.
4733	*/
4734	touch_nmi_watchdog();
4735	}
4736	}
4737
4738	for_each_pool(pool, pi) {
4739	struct worker *worker;
4740	bool first = true;
4741
4742	spin_lock_irqsave(&pool->lock, flags);
4743	if (pool->nr_workers == pool->nr_idle)
4744	goto next_pool;
4745
4746	pr_info("pool %d:", pool->id);
4747	pr_cont_pool_info(pool);
4748	pr_cont(" hung=%us workers=%d",
4749	jiffies_to_msecs(jiffies - pool->watchdog_ts) / 1000,
4750	pool->nr_workers);
4751	if (pool->manager)
4752	pr_cont(" manager: %d",
4753	task_pid_nr(pool->manager->task));
4754	list_for_each_entry(worker, &pool->idle_list, entry) {
4755	pr_cont(" %s%d", first ? "idle: " : "",
4756	task_pid_nr(worker->task));
4757	first = false;
4758	}
4759	pr_cont("\n");
4760	next_pool:
4761	spin_unlock_irqrestore(&pool->lock, flags);
4762	/*
4763	* We could be printing a lot from atomic context, e.g.
4764	* sysrq-t -> show_workqueue_state(). Avoid triggering
4765	* hard lockup.
4766	*/
4767	touch_nmi_watchdog();
4768	}
4769
4770	rcu_read_unlock();
4771	}
4772
4773	/* used to show worker information through /proc/PID/{comm,stat,status} */
4774	void wq_worker_comm(char buf, size_t size, struct task_struct task)
4775	{
4776	int off;
4777
4778	/* always show the actual comm */
4779	off = strscpy(buf, task->comm, size);
4780	if (off < 0)
4781	return;
4782
4783	/* stabilize PF_WQ_WORKER and worker pool association */
4784	mutex_lock(&wq_pool_attach_mutex);
4785
4786	if (task->flags & PF_WQ_WORKER) {
4787	struct worker *worker = kthread_data(task);
4788	struct worker_pool *pool = worker->pool;
4789
4790	if (pool) {
4791	spin_lock_irq(&pool->lock);
4792	/*
4793	* ->desc tracks information (wq name or
4794	* set_worker_desc()) for the latest execution. If
4795	* current, prepend '+', otherwise '-'.
4796	*/
4797	if (worker->desc[0] != '\0') {
4798	if (worker->current_work)
4799	scnprintf(buf + off, size - off, "+%s",
4800	worker->desc);
4801	else
4802	scnprintf(buf + off, size - off, "-%s",
4803	worker->desc);
4804	}
4805	spin_unlock_irq(&pool->lock);
4806	}
4807	}
4808
4809	mutex_unlock(&wq_pool_attach_mutex);
4810	}
4811
4812	#ifdef CONFIG_SMP
4813
4814	/*
4815	* CPU hotplug.
4816	*
4817	* There are two challenges in supporting CPU hotplug. Firstly, there
4818	* are a lot of assumptions on strong associations among work, pwq and
4819	* pool which make migrating pending and scheduled works very
4820	* difficult to implement without impacting hot paths. Secondly,
4821	* worker pools serve mix of short, long and very long running works making
4822	* blocked draining impractical.
4823	*
4824	* This is solved by allowing the pools to be disassociated from the CPU
4825	* running as an unbound one and allowing it to be reattached later if the
4826	* cpu comes back online.
4827	*/
4828
4829	static void unbind_workers(int cpu)
4830	{
4831	struct worker_pool *pool;
4832	struct worker *worker;
4833
4834	for_each_cpu_worker_pool(pool, cpu) {
4835	mutex_lock(&wq_pool_attach_mutex);
4836	spin_lock_irq(&pool->lock);
4837
4838	/*
4839	* We've blocked all attach/detach operations. Make all workers
4840	* unbound and set DISASSOCIATED. Before this, all workers
4841	* except for the ones which are still executing works from
4842	* before the last CPU down must be on the cpu. After
4843	* this, they may become diasporas.
4844	*/
4845	for_each_pool_worker(worker, pool)
4846	worker->flags \|= WORKER_UNBOUND;
4847
4848	pool->flags \|= POOL_DISASSOCIATED;
4849
4850	spin_unlock_irq(&pool->lock);
4851	mutex_unlock(&wq_pool_attach_mutex);
4852
4853	/*
4854	* Call schedule() so that we cross rq->lock and thus can
4855	* guarantee sched callbacks see the %WORKER_UNBOUND flag.
4856	* This is necessary as scheduler callbacks may be invoked
4857	* from other cpus.
4858	*/
4859	schedule();
4860
4861	/*
4862	* Sched callbacks are disabled now. Zap nr_running.
4863	* After this, nr_running stays zero and need_more_worker()
4864	* and keep_working() are always true as long as the
4865	* worklist is not empty. This pool now behaves as an
4866	* unbound (in terms of concurrency management) pool which
4867	* are served by workers tied to the pool.
4868	*/
4869	atomic_set(&pool->nr_running, 0);
4870
4871	/*
4872	* With concurrency management just turned off, a busy
4873	* worker blocking could lead to lengthy stalls. Kick off
4874	* unbound chain execution of currently pending work items.
4875	*/
4876	spin_lock_irq(&pool->lock);
4877	wake_up_worker(pool);
4878	spin_unlock_irq(&pool->lock);
4879	}
4880	}
4881
4882	/**
4883	* rebind_workers - rebind all workers of a pool to the associated CPU
4884	* @pool: pool of interest
4885	*
4886	* @pool->cpu is coming online. Rebind all workers to the CPU.
4887	*/
4888	static void rebind_workers(struct worker_pool *pool)
4889	{
4890	struct worker *worker;
4891
4892	lockdep_assert_held(&wq_pool_attach_mutex);
4893
4894	/*
4895	* Restore CPU affinity of all workers. As all idle workers should
4896	* be on the run-queue of the associated CPU before any local
4897	* wake-ups for concurrency management happen, restore CPU affinity
4898	* of all workers first and then clear UNBOUND. As we're called
4899	* from CPU_ONLINE, the following shouldn't fail.
4900	*/
4901	for_each_pool_worker(worker, pool)
4902	WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
4903	pool->attrs->cpumask) < 0);
4904
4905	spin_lock_irq(&pool->lock);
4906
4907	pool->flags &= ~POOL_DISASSOCIATED;
4908
4909	for_each_pool_worker(worker, pool) {
4910	unsigned int worker_flags = worker->flags;
4911
4912	/*
4913	* A bound idle worker should actually be on the runqueue
4914	* of the associated CPU for local wake-ups targeting it to
4915	* work. Kick all idle workers so that they migrate to the
4916	* associated CPU. Doing this in the same loop as
4917	* replacing UNBOUND with REBOUND is safe as no worker will
4918	* be bound before @pool->lock is released.
4919	*/
4920	if (worker_flags & WORKER_IDLE)
4921	wake_up_process(worker->task);
4922
4923	/*
4924	* We want to clear UNBOUND but can't directly call
4925	* worker_clr_flags() or adjust nr_running. Atomically
4926	* replace UNBOUND with another NOT_RUNNING flag REBOUND.
4927	* @worker will clear REBOUND using worker_clr_flags() when
4928	* it initiates the next execution cycle thus restoring
4929	* concurrency management. Note that when or whether
4930	* @worker clears REBOUND doesn't affect correctness.
4931	*
4932	* WRITE_ONCE() is necessary because @worker->flags may be
4933	* tested without holding any lock in
4934	* wq_worker_running(). Without it, NOT_RUNNING test may
4935	* fail incorrectly leading to premature concurrency
4936	* management operations.
4937	*/
4938	WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND));
4939	worker_flags \|= WORKER_REBOUND;
4940	worker_flags &= ~WORKER_UNBOUND;
4941	WRITE_ONCE(worker->flags, worker_flags);
4942	}
4943
4944	spin_unlock_irq(&pool->lock);
4945	}
4946
4947	/**
4948	* restore_unbound_workers_cpumask - restore cpumask of unbound workers
4949	* @pool: unbound pool of interest
4950	* @cpu: the CPU which is coming up
4951	*
4952	* An unbound pool may end up with a cpumask which doesn't have any online
4953	* CPUs. When a worker of such pool get scheduled, the scheduler resets
4954	* its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
4955	* online CPU before, cpus_allowed of all its workers should be restored.
4956	*/
4957	static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu)
4958	{
4959	static cpumask_t cpumask;
4960	struct worker *worker;
4961
4962	lockdep_assert_held(&wq_pool_attach_mutex);
4963
4964	/* is @cpu allowed for @pool? */
4965	if (!cpumask_test_cpu(cpu, pool->attrs->cpumask))
4966	return;
4967
4968	cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask);
4969
4970	/* as we're called from CPU_ONLINE, the following shouldn't fail */
4971	for_each_pool_worker(worker, pool)
4972	WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, &cpumask) < 0);
4973	}
4974
4975	int workqueue_prepare_cpu(unsigned int cpu)
4976	{
4977	struct worker_pool *pool;
4978
4979	for_each_cpu_worker_pool(pool, cpu) {
4980	if (pool->nr_workers)
4981	continue;
4982	if (!create_worker(pool))
4983	return -ENOMEM;
4984	}
4985	return 0;
4986	}
4987
4988	int workqueue_online_cpu(unsigned int cpu)
4989	{
4990	struct worker_pool *pool;
4991	struct workqueue_struct *wq;
4992	int pi;
4993
4994	mutex_lock(&wq_pool_mutex);
4995
4996	for_each_pool(pool, pi) {
4997	mutex_lock(&wq_pool_attach_mutex);
4998
4999	if (pool->cpu == cpu)
5000	rebind_workers(pool);
5001	else if (pool->cpu < 0)
5002	restore_unbound_workers_cpumask(pool, cpu);
5003
5004	mutex_unlock(&wq_pool_attach_mutex);
5005	}
5006
5007	/* update NUMA affinity of unbound workqueues */
5008	list_for_each_entry(wq, &workqueues, list)
5009	wq_update_unbound_numa(wq, cpu, true);
5010
5011	mutex_unlock(&wq_pool_mutex);
5012	return 0;
5013	}
5014
5015	int workqueue_offline_cpu(unsigned int cpu)
5016	{
5017	struct workqueue_struct *wq;
5018
5019	/* unbinding per-cpu workers should happen on the local CPU */
5020	if (WARN_ON(cpu != smp_processor_id()))
5021	return -1;
5022
5023	unbind_workers(cpu);
5024
5025	/* update NUMA affinity of unbound workqueues */
5026	mutex_lock(&wq_pool_mutex);
5027	list_for_each_entry(wq, &workqueues, list)
5028	wq_update_unbound_numa(wq, cpu, false);
5029	mutex_unlock(&wq_pool_mutex);
5030
5031	return 0;
5032	}
5033
5034	struct work_for_cpu {
5035	struct work_struct work;
5036	long (fn)(void );
5037	void *arg;
5038	long ret;
5039	};
5040
5041	static void work_for_cpu_fn(struct work_struct *work)
5042	{
5043	struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work);
5044
5045	wfc->ret = wfc->fn(wfc->arg);
5046	}
5047
5048	/**
5049	* work_on_cpu - run a function in thread context on a particular cpu
5050	* @cpu: the cpu to run on
5051	* @fn: the function to run
5052	* @arg: the function arg
5053	*
5054	* It is up to the caller to ensure that the cpu doesn't go offline.
5055	* The caller must not hold any locks which would prevent @fn from completing.
5056	*
5057	* Return: The value @fn returns.
5058	*/
5059	long work_on_cpu(int cpu, long (fn)(void ), void *arg)
5060	{
5061	struct work_for_cpu wfc = { .fn = fn, .arg = arg };
5062
5063	INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn);
5064	schedule_work_on(cpu, &wfc.work);
5065	flush_work(&wfc.work);
5066	destroy_work_on_stack(&wfc.work);
5067	return wfc.ret;
5068	}
5069	EXPORT_SYMBOL_GPL(work_on_cpu);
5070
5071	/**
5072	* work_on_cpu_safe - run a function in thread context on a particular cpu
5073	* @cpu: the cpu to run on
5074	* @fn: the function to run
5075	* @arg: the function argument
5076	*
5077	* Disables CPU hotplug and calls work_on_cpu(). The caller must not hold
5078	* any locks which would prevent @fn from completing.
5079	*
5080	* Return: The value @fn returns.
5081	*/
5082	long work_on_cpu_safe(int cpu, long (fn)(void ), void *arg)
5083	{
5084	long ret = -ENODEV;
5085
5086	get_online_cpus();
5087	if (cpu_online(cpu))
5088	ret = work_on_cpu(cpu, fn, arg);
5089	put_online_cpus();
5090	return ret;
5091	}
5092	EXPORT_SYMBOL_GPL(work_on_cpu_safe);
5093	#endif /* CONFIG_SMP */
5094
5095	#ifdef CONFIG_FREEZER
5096
5097	/**
5098	* freeze_workqueues_begin - begin freezing workqueues
5099	*
5100	* Start freezing workqueues. After this function returns, all freezable
5101	* workqueues will queue new works to their delayed_works list instead of
5102	* pool->worklist.
5103	*
5104	* CONTEXT:
5105	* Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
5106	*/
5107	void freeze_workqueues_begin(void)
5108	{
5109	struct workqueue_struct *wq;
5110	struct pool_workqueue *pwq;
5111
5112	mutex_lock(&wq_pool_mutex);
5113
5114	WARN_ON_ONCE(workqueue_freezing);
5115	workqueue_freezing = true;
5116
5117	list_for_each_entry(wq, &workqueues, list) {
5118	mutex_lock(&wq->mutex);
5119	for_each_pwq(pwq, wq)
5120	pwq_adjust_max_active(pwq);
5121	mutex_unlock(&wq->mutex);
5122	}
5123
5124	mutex_unlock(&wq_pool_mutex);
5125	}
5126
5127	/**
5128	* freeze_workqueues_busy - are freezable workqueues still busy?
5129	*
5130	* Check whether freezing is complete. This function must be called
5131	* between freeze_workqueues_begin() and thaw_workqueues().
5132	*
5133	* CONTEXT:
5134	* Grabs and releases wq_pool_mutex.
5135	*
5136	* Return:
5137	* %true if some freezable workqueues are still busy. %false if freezing
5138	* is complete.
5139	*/
5140	bool freeze_workqueues_busy(void)
5141	{
5142	bool busy = false;
5143	struct workqueue_struct *wq;
5144	struct pool_workqueue *pwq;
5145
5146	mutex_lock(&wq_pool_mutex);
5147
5148	WARN_ON_ONCE(!workqueue_freezing);
5149
5150	list_for_each_entry(wq, &workqueues, list) {
5151	if (!(wq->flags & WQ_FREEZABLE))
5152	continue;
5153	/*
5154	* nr_active is monotonically decreasing. It's safe
5155	* to peek without lock.
5156	*/
5157	rcu_read_lock();
5158	for_each_pwq(pwq, wq) {
5159	WARN_ON_ONCE(pwq->nr_active < 0);
5160	if (pwq->nr_active) {
5161	busy = true;
5162	rcu_read_unlock();
5163	goto out_unlock;
5164	}
5165	}
5166	rcu_read_unlock();
5167	}
5168	out_unlock:
5169	mutex_unlock(&wq_pool_mutex);
5170	return busy;
5171	}
5172
5173	/**
5174	* thaw_workqueues - thaw workqueues
5175	*
5176	* Thaw workqueues. Normal queueing is restored and all collected
5177	* frozen works are transferred to their respective pool worklists.
5178	*
5179	* CONTEXT:
5180	* Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
5181	*/
5182	void thaw_workqueues(void)
5183	{
5184	struct workqueue_struct *wq;
5185	struct pool_workqueue *pwq;
5186
5187	mutex_lock(&wq_pool_mutex);
5188
5189	if (!workqueue_freezing)
5190	goto out_unlock;
5191
5192	workqueue_freezing = false;
5193
5194	/* restore max_active and repopulate worklist */
5195	list_for_each_entry(wq, &workqueues, list) {
5196	mutex_lock(&wq->mutex);
5197	for_each_pwq(pwq, wq)
5198	pwq_adjust_max_active(pwq);
5199	mutex_unlock(&wq->mutex);
5200	}
5201
5202	out_unlock:
5203	mutex_unlock(&wq_pool_mutex);
5204	}
5205	#endif /* CONFIG_FREEZER */
5206
5207	static int workqueue_apply_unbound_cpumask(void)
5208	{
5209	LIST_HEAD(ctxs);
5210	int ret = 0;
5211	struct workqueue_struct *wq;
5212	struct apply_wqattrs_ctx ctx, n;
5213
5214	lockdep_assert_held(&wq_pool_mutex);
5215
5216	list_for_each_entry(wq, &workqueues, list) {
5217	if (!(wq->flags & WQ_UNBOUND))
5218	continue;
5219	/* creating multiple pwqs breaks ordering guarantee */
5220	if (wq->flags & __WQ_ORDERED)
5221	continue;
5222
5223	ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs);
5224	if (!ctx) {
5225	ret = -ENOMEM;
5226	break;
5227	}
5228
5229	list_add_tail(&ctx->list, &ctxs);
5230	}
5231
5232	list_for_each_entry_safe(ctx, n, &ctxs, list) {
5233	if (!ret)
5234	apply_wqattrs_commit(ctx);
5235	apply_wqattrs_cleanup(ctx);
5236	}
5237
5238	return ret;
5239	}
5240
5241	/**
5242	* workqueue_set_unbound_cpumask - Set the low-level unbound cpumask
5243	* @cpumask: the cpumask to set
5244	*
5245	* The low-level workqueues cpumask is a global cpumask that limits
5246	* the affinity of all unbound workqueues. This function check the @cpumask
5247	* and apply it to all unbound workqueues and updates all pwqs of them.
5248	*
5249	* Retun: 0 - Success
5250	* -EINVAL - Invalid @cpumask
5251	* -ENOMEM - Failed to allocate memory for attrs or pwqs.
5252	*/
5253	int workqueue_set_unbound_cpumask(cpumask_var_t cpumask)
5254	{
5255	int ret = -EINVAL;
5256	cpumask_var_t saved_cpumask;
5257
5258	if (!zalloc_cpumask_var(&saved_cpumask, GFP_KERNEL))
5259	return -ENOMEM;
5260
5261	/*
5262	* Not excluding isolated cpus on purpose.
5263	* If the user wishes to include them, we allow that.
5264	*/
5265	cpumask_and(cpumask, cpumask, cpu_possible_mask);
5266	if (!cpumask_empty(cpumask)) {
5267	apply_wqattrs_lock();
5268
5269	/* save the old wq_unbound_cpumask. */
5270	cpumask_copy(saved_cpumask, wq_unbound_cpumask);
5271
5272	/* update wq_unbound_cpumask at first and apply it to wqs. */
5273	cpumask_copy(wq_unbound_cpumask, cpumask);
5274	ret = workqueue_apply_unbound_cpumask();
5275
5276	/* restore the wq_unbound_cpumask when failed. */
5277	if (ret < 0)
5278	cpumask_copy(wq_unbound_cpumask, saved_cpumask);
5279
5280	apply_wqattrs_unlock();
5281	}
5282
5283	free_cpumask_var(saved_cpumask);
5284	return ret;
5285	}
5286
5287	#ifdef CONFIG_SYSFS
5288	/*
5289	* Workqueues with WQ_SYSFS flag set is visible to userland via
5290	* /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
5291	* following attributes.
5292	*
5293	* per_cpu RO bool : whether the workqueue is per-cpu or unbound
5294	* max_active RW int : maximum number of in-flight work items
5295	*
5296	* Unbound workqueues have the following extra attributes.
5297	*
5298	* pool_ids RO int : the associated pool IDs for each node
5299	* nice RW int : nice value of the workers
5300	* cpumask RW mask : bitmask of allowed CPUs for the workers
5301	* numa RW bool : whether enable NUMA affinity
5302	*/
5303	struct wq_device {
5304	struct workqueue_struct *wq;
5305	struct device dev;
5306	};
5307
5308	static struct workqueue_struct dev_to_wq(struct device dev)
5309	{
5310	struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
5311
5312	return wq_dev->wq;
5313	}
5314
5315	static ssize_t per_cpu_show(struct device dev, struct device_attribute attr,
5316	char *buf)
5317	{
5318	struct workqueue_struct *wq = dev_to_wq(dev);
5319
5320	return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND));
5321	}
5322	static DEVICE_ATTR_RO(per_cpu);
5323
5324	static ssize_t max_active_show(struct device *dev,
5325	struct device_attribute attr, char buf)
5326	{
5327	struct workqueue_struct *wq = dev_to_wq(dev);
5328
5329	return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active);
5330	}
5331
5332	static ssize_t max_active_store(struct device *dev,
5333	struct device_attribute attr, const char buf,
5334	size_t count)
5335	{
5336	struct workqueue_struct *wq = dev_to_wq(dev);
5337	int val;
5338
5339	if (sscanf(buf, "%d", &val) != 1 \|\| val <= 0)
5340	return -EINVAL;
5341
5342	workqueue_set_max_active(wq, val);
5343	return count;
5344	}
5345	static DEVICE_ATTR_RW(max_active);
5346
5347	static struct attribute *wq_sysfs_attrs[] = {
5348	&dev_attr_per_cpu.attr,
5349	&dev_attr_max_active.attr,
5350	NULL,
5351	};
5352	ATTRIBUTE_GROUPS(wq_sysfs);
5353
5354	static ssize_t wq_pool_ids_show(struct device *dev,
5355	struct device_attribute attr, char buf)
5356	{
5357	struct workqueue_struct *wq = dev_to_wq(dev);
5358	const char *delim = "";
5359	int node, written = 0;
5360
5361	get_online_cpus();
5362	rcu_read_lock();
5363	for_each_node(node) {
5364	written += scnprintf(buf + written, PAGE_SIZE - written,
5365	"%s%d:%d", delim, node,
5366	unbound_pwq_by_node(wq, node)->pool->id);
5367	delim = " ";
5368	}
5369	written += scnprintf(buf + written, PAGE_SIZE - written, "\n");
5370	rcu_read_unlock();
5371	put_online_cpus();
5372
5373	return written;
5374	}
5375
5376	static ssize_t wq_nice_show(struct device dev, struct device_attribute attr,
5377	char *buf)
5378	{
5379	struct workqueue_struct *wq = dev_to_wq(dev);
5380	int written;
5381
5382	mutex_lock(&wq->mutex);
5383	written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice);
5384	mutex_unlock(&wq->mutex);
5385
5386	return written;
5387	}
5388
5389	/* prepare workqueue_attrs for sysfs store operations */
5390	static struct workqueue_attrs wq_sysfs_prep_attrs(struct workqueue_struct wq)
5391	{
5392	struct workqueue_attrs *attrs;
5393
5394	lockdep_assert_held(&wq_pool_mutex);
5395
5396	attrs = alloc_workqueue_attrs();
5397	if (!attrs)
5398	return NULL;
5399
5400	copy_workqueue_attrs(attrs, wq->unbound_attrs);
5401	return attrs;
5402	}
5403
5404	static ssize_t wq_nice_store(struct device dev, struct device_attribute attr,
5405	const char *buf, size_t count)
5406	{
5407	struct workqueue_struct *wq = dev_to_wq(dev);
5408	struct workqueue_attrs *attrs;
5409	int ret = -ENOMEM;
5410
5411	apply_wqattrs_lock();
5412
5413	attrs = wq_sysfs_prep_attrs(wq);
5414	if (!attrs)
5415	goto out_unlock;
5416
5417	if (sscanf(buf, "%d", &attrs->nice) == 1 &&
5418	attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE)
5419	ret = apply_workqueue_attrs_locked(wq, attrs);
5420	else
5421	ret = -EINVAL;
5422
5423	out_unlock:
5424	apply_wqattrs_unlock();
5425	free_workqueue_attrs(attrs);
5426	return ret ?: count;
5427	}
5428
5429	static ssize_t wq_cpumask_show(struct device *dev,
5430	struct device_attribute attr, char buf)
5431	{
5432	struct workqueue_struct *wq = dev_to_wq(dev);
5433	int written;
5434
5435	mutex_lock(&wq->mutex);
5436	written = scnprintf(buf, PAGE_SIZE, "%*pb\n",
5437	cpumask_pr_args(wq->unbound_attrs->cpumask));
5438	mutex_unlock(&wq->mutex);
5439	return written;
5440	}
5441
5442	static ssize_t wq_cpumask_store(struct device *dev,
5443	struct device_attribute *attr,
5444	const char *buf, size_t count)
5445	{
5446	struct workqueue_struct *wq = dev_to_wq(dev);
5447	struct workqueue_attrs *attrs;
5448	int ret = -ENOMEM;
5449
5450	apply_wqattrs_lock();
5451
5452	attrs = wq_sysfs_prep_attrs(wq);
5453	if (!attrs)
5454	goto out_unlock;
5455
5456	ret = cpumask_parse(buf, attrs->cpumask);
5457	if (!ret)
5458	ret = apply_workqueue_attrs_locked(wq, attrs);
5459
5460	out_unlock:
5461	apply_wqattrs_unlock();
5462	free_workqueue_attrs(attrs);
5463	return ret ?: count;
5464	}
5465
5466	static ssize_t wq_numa_show(struct device dev, struct device_attribute attr,
5467	char *buf)
5468	{
5469	struct workqueue_struct *wq = dev_to_wq(dev);
5470	int written;
5471
5472	mutex_lock(&wq->mutex);
5473	written = scnprintf(buf, PAGE_SIZE, "%d\n",
5474	!wq->unbound_attrs->no_numa);
5475	mutex_unlock(&wq->mutex);
5476
5477	return written;
5478	}
5479
5480	static ssize_t wq_numa_store(struct device dev, struct device_attribute attr,
5481	const char *buf, size_t count)
5482	{
5483	struct workqueue_struct *wq = dev_to_wq(dev);
5484	struct workqueue_attrs *attrs;
5485	int v, ret = -ENOMEM;
5486
5487	apply_wqattrs_lock();
5488
5489	attrs = wq_sysfs_prep_attrs(wq);
5490	if (!attrs)
5491	goto out_unlock;
5492
5493	ret = -EINVAL;
5494	if (sscanf(buf, "%d", &v) == 1) {
5495	attrs->no_numa = !v;
5496	ret = apply_workqueue_attrs_locked(wq, attrs);
5497	}
5498
5499	out_unlock:
5500	apply_wqattrs_unlock();
5501	free_workqueue_attrs(attrs);
5502	return ret ?: count;
5503	}
5504
5505	static struct device_attribute wq_sysfs_unbound_attrs[] = {
5506	__ATTR(pool_ids, 0444, wq_pool_ids_show, NULL),
5507	__ATTR(nice, 0644, wq_nice_show, wq_nice_store),
5508	__ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store),
5509	__ATTR(numa, 0644, wq_numa_show, wq_numa_store),
5510	__ATTR_NULL,
5511	};
5512
5513	static struct bus_type wq_subsys = {
5514	.name = "workqueue",
5515	.dev_groups = wq_sysfs_groups,
5516	};
5517
5518	static ssize_t wq_unbound_cpumask_show(struct device *dev,
5519	struct device_attribute attr, char buf)
5520	{
5521	int written;
5522
5523	mutex_lock(&wq_pool_mutex);
5524	written = scnprintf(buf, PAGE_SIZE, "%*pb\n",
5525	cpumask_pr_args(wq_unbound_cpumask));
5526	mutex_unlock(&wq_pool_mutex);
5527
5528	return written;
5529	}
5530
5531	static ssize_t wq_unbound_cpumask_store(struct device *dev,
5532	struct device_attribute attr, const char buf, size_t count)
5533	{
5534	cpumask_var_t cpumask;
5535	int ret;
5536
5537	if (!zalloc_cpumask_var(&cpumask, GFP_KERNEL))
5538	return -ENOMEM;
5539
5540	ret = cpumask_parse(buf, cpumask);
5541	if (!ret)
5542	ret = workqueue_set_unbound_cpumask(cpumask);
5543
5544	free_cpumask_var(cpumask);
5545	return ret ? ret : count;
5546	}
5547
5548	static struct device_attribute wq_sysfs_cpumask_attr =
5549	__ATTR(cpumask, 0644, wq_unbound_cpumask_show,
5550	wq_unbound_cpumask_store);
5551
5552	static int __init wq_sysfs_init(void)
5553	{
5554	int err;
5555
5556	err = subsys_virtual_register(&wq_subsys, NULL);
5557	if (err)
5558	return err;
5559
5560	return device_create_file(wq_subsys.dev_root, &wq_sysfs_cpumask_attr);
5561	}
5562	core_initcall(wq_sysfs_init);
5563
5564	static void wq_device_release(struct device *dev)
5565	{
5566	struct wq_device *wq_dev = container_of(dev, struct wq_device, dev);
5567
5568	kfree(wq_dev);
5569	}
5570
5571	/**
5572	* workqueue_sysfs_register - make a workqueue visible in sysfs
5573	* @wq: the workqueue to register
5574	*
5575	* Expose @wq in sysfs under /sys/bus/workqueue/devices.
5576	* alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
5577	* which is the preferred method.
5578	*
5579	* Workqueue user should use this function directly iff it wants to apply
5580	* workqueue_attrs before making the workqueue visible in sysfs; otherwise,
5581	* apply_workqueue_attrs() may race against userland updating the
5582	* attributes.
5583	*
5584	* Return: 0 on success, -errno on failure.
5585	*/
5586	int workqueue_sysfs_register(struct workqueue_struct *wq)
5587	{
5588	struct wq_device *wq_dev;
5589	int ret;
5590
5591	/*
5592	* Adjusting max_active or creating new pwqs by applying
5593	* attributes breaks ordering guarantee. Disallow exposing ordered
5594	* workqueues.
5595	*/
5596	if (WARN_ON(wq->flags & __WQ_ORDERED_EXPLICIT))
5597	return -EINVAL;
5598
5599	wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL);
5600	if (!wq_dev)
5601	return -ENOMEM;
5602
5603	wq_dev->wq = wq;
5604	wq_dev->dev.bus = &wq_subsys;
5605	wq_dev->dev.release = wq_device_release;
5606	dev_set_name(&wq_dev->dev, "%s", wq->name);
5607
5608	/*
5609	* unbound_attrs are created separately. Suppress uevent until
5610	* everything is ready.
5611	*/
5612	dev_set_uevent_suppress(&wq_dev->dev, true);
5613
5614	ret = device_register(&wq_dev->dev);
5615	if (ret) {
5616	put_device(&wq_dev->dev);
5617	wq->wq_dev = NULL;
5618	return ret;
5619	}
5620
5621	if (wq->flags & WQ_UNBOUND) {
5622	struct device_attribute *attr;
5623
5624	for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) {
5625	ret = device_create_file(&wq_dev->dev, attr);
5626	if (ret) {
5627	device_unregister(&wq_dev->dev);
5628	wq->wq_dev = NULL;
5629	return ret;
5630	}
5631	}
5632	}
5633
5634	dev_set_uevent_suppress(&wq_dev->dev, false);
5635	kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD);
5636	return 0;
5637	}
5638
5639	/**
5640	* workqueue_sysfs_unregister - undo workqueue_sysfs_register()
5641	* @wq: the workqueue to unregister
5642	*
5643	* If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
5644	*/
5645	static void workqueue_sysfs_unregister(struct workqueue_struct *wq)
5646	{
5647	struct wq_device *wq_dev = wq->wq_dev;
5648
5649	if (!wq->wq_dev)
5650	return;
5651
5652	wq->wq_dev = NULL;
5653	device_unregister(&wq_dev->dev);
5654	}
5655	#else /* CONFIG_SYSFS */
5656	static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { }
5657	#endif /* CONFIG_SYSFS */
5658
5659	/*
5660	* Workqueue watchdog.
5661	*
5662	* Stall may be caused by various bugs - missing WQ_MEM_RECLAIM, illegal
5663	* flush dependency, a concurrency managed work item which stays RUNNING
5664	* indefinitely. Workqueue stalls can be very difficult to debug as the
5665	* usual warning mechanisms don't trigger and internal workqueue state is
5666	* largely opaque.
5667	*
5668	* Workqueue watchdog monitors all worker pools periodically and dumps
5669	* state if some pools failed to make forward progress for a while where
5670	* forward progress is defined as the first item on ->worklist changing.
5671	*
5672	* This mechanism is controlled through the kernel parameter
5673	* "workqueue.watchdog_thresh" which can be updated at runtime through the
5674	* corresponding sysfs parameter file.
5675	*/
5676	#ifdef CONFIG_WQ_WATCHDOG
5677
5678	static unsigned long wq_watchdog_thresh = 30;
5679	static struct timer_list wq_watchdog_timer;
5680
5681	static unsigned long wq_watchdog_touched = INITIAL_JIFFIES;
5682	static DEFINE_PER_CPU(unsigned long, wq_watchdog_touched_cpu) = INITIAL_JIFFIES;
5683
5684	static void wq_watchdog_reset_touched(void)
5685	{
5686	int cpu;
5687
5688	wq_watchdog_touched = jiffies;
5689	for_each_possible_cpu(cpu)
5690	per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies;
5691	}
5692
5693	static void wq_watchdog_timer_fn(struct timer_list *unused)
5694	{
5695	unsigned long thresh = READ_ONCE(wq_watchdog_thresh) * HZ;
5696	bool lockup_detected = false;
5697	struct worker_pool *pool;
5698	int pi;
5699
5700	if (!thresh)
5701	return;
5702
5703	rcu_read_lock();
5704
5705	for_each_pool(pool, pi) {
5706	unsigned long pool_ts, touched, ts;
5707
5708	if (list_empty(&pool->worklist))
5709	continue;
5710
5711	/* get the latest of pool and touched timestamps */
5712	pool_ts = READ_ONCE(pool->watchdog_ts);
5713	touched = READ_ONCE(wq_watchdog_touched);
5714
5715	if (time_after(pool_ts, touched))
5716	ts = pool_ts;
5717	else
5718	ts = touched;
5719
5720	if (pool->cpu >= 0) {
5721	unsigned long cpu_touched =
5722	READ_ONCE(per_cpu(wq_watchdog_touched_cpu,
5723	pool->cpu));
5724	if (time_after(cpu_touched, ts))
5725	ts = cpu_touched;
5726	}
5727
5728	/* did we stall? */
5729	if (time_after(jiffies, ts + thresh)) {
5730	lockup_detected = true;
5731	pr_emerg("BUG: workqueue lockup - pool");
5732	pr_cont_pool_info(pool);
5733	pr_cont(" stuck for %us!\n",
5734	jiffies_to_msecs(jiffies - pool_ts) / 1000);
5735	}
5736	}
5737
5738	rcu_read_unlock();
5739
5740	if (lockup_detected)
5741	show_workqueue_state();
5742
5743	wq_watchdog_reset_touched();
5744	mod_timer(&wq_watchdog_timer, jiffies + thresh);
5745	}
5746
5747	notrace void wq_watchdog_touch(int cpu)
5748	{
5749	if (cpu >= 0)
5750	per_cpu(wq_watchdog_touched_cpu, cpu) = jiffies;
5751	else
5752	wq_watchdog_touched = jiffies;
5753	}
5754
5755	static void wq_watchdog_set_thresh(unsigned long thresh)
5756	{
5757	wq_watchdog_thresh = 0;
5758	del_timer_sync(&wq_watchdog_timer);
5759
5760	if (thresh) {
5761	wq_watchdog_thresh = thresh;
5762	wq_watchdog_reset_touched();
5763	mod_timer(&wq_watchdog_timer, jiffies + thresh * HZ);
5764	}
5765	}
5766
5767	static int wq_watchdog_param_set_thresh(const char *val,
5768	const struct kernel_param *kp)
5769	{
5770	unsigned long thresh;
5771	int ret;
5772
5773	ret = kstrtoul(val, 0, &thresh);
5774	if (ret)
5775	return ret;
5776
5777	if (system_wq)
5778	wq_watchdog_set_thresh(thresh);
5779	else
5780	wq_watchdog_thresh = thresh;
5781
5782	return 0;
5783	}
5784
5785	static const struct kernel_param_ops wq_watchdog_thresh_ops = {
5786	.set = wq_watchdog_param_set_thresh,
5787	.get = param_get_ulong,
5788	};
5789
5790	module_param_cb(watchdog_thresh, &wq_watchdog_thresh_ops, &wq_watchdog_thresh,
5791	0644);
5792
5793	static void wq_watchdog_init(void)
5794	{
5795	timer_setup(&wq_watchdog_timer, wq_watchdog_timer_fn, TIMER_DEFERRABLE);
5796	wq_watchdog_set_thresh(wq_watchdog_thresh);
5797	}
5798
5799	#else /* CONFIG_WQ_WATCHDOG */
5800
5801	static inline void wq_watchdog_init(void) { }
5802
5803	#endif /* CONFIG_WQ_WATCHDOG */
5804
5805	static void __init wq_numa_init(void)
5806	{
5807	cpumask_var_t *tbl;
5808	int node, cpu;
5809
5810	if (num_possible_nodes() <= 1)
5811	return;
5812
5813	if (wq_disable_numa) {
5814	pr_info("workqueue: NUMA affinity support disabled\n");
5815	return;
5816	}
5817
5818	wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs();
5819	BUG_ON(!wq_update_unbound_numa_attrs_buf);
5820
5821	/*
5822	* We want masks of possible CPUs of each node which isn't readily
5823	* available. Build one from cpu_to_node() which should have been
5824	* fully initialized by now.
5825	*/
5826	tbl = kcalloc(nr_node_ids, sizeof(tbl[0]), GFP_KERNEL);
5827	BUG_ON(!tbl);
5828
5829	for_each_node(node)
5830	BUG_ON(!zalloc_cpumask_var_node(&tbl[node], GFP_KERNEL,
5831	node_online(node) ? node : NUMA_NO_NODE));
5832
5833	for_each_possible_cpu(cpu) {
5834	node = cpu_to_node(cpu);
5835	if (WARN_ON(node == NUMA_NO_NODE)) {
5836	pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu);
5837	/* happens iff arch is bonkers, let's just proceed */
5838	return;
5839	}
5840	cpumask_set_cpu(cpu, tbl[node]);
5841	}
5842
5843	wq_numa_possible_cpumask = tbl;
5844	wq_numa_enabled = true;
5845	}
5846
5847	/**
5848	* workqueue_init_early - early init for workqueue subsystem
5849	*
5850	* This is the first half of two-staged workqueue subsystem initialization
5851	* and invoked as soon as the bare basics - memory allocation, cpumasks and
5852	* idr are up. It sets up all the data structures and system workqueues
5853	* and allows early boot code to create workqueues and queue/cancel work
5854	* items. Actual work item execution starts only after kthreads can be
5855	* created and scheduled right before early initcalls.
5856	*/
5857	int __init workqueue_init_early(void)
5858	{
5859	int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL };
5860	int hk_flags = HK_FLAG_DOMAIN \| HK_FLAG_WQ;
5861	int i, cpu;
5862
5863	WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long));
5864
5865	BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask, GFP_KERNEL));
5866	cpumask_copy(wq_unbound_cpumask, housekeeping_cpumask(hk_flags));
5867
5868	pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC);
5869
5870	/* initialize CPU pools */
5871	for_each_possible_cpu(cpu) {
5872	struct worker_pool *pool;
5873
5874	i = 0;
5875	for_each_cpu_worker_pool(pool, cpu) {
5876	BUG_ON(init_worker_pool(pool));
5877	pool->cpu = cpu;
5878	cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu));
5879	pool->attrs->nice = std_nice[i++];
5880	pool->node = cpu_to_node(cpu);
5881
5882	/* alloc pool ID */
5883	mutex_lock(&wq_pool_mutex);
5884	BUG_ON(worker_pool_assign_id(pool));
5885	mutex_unlock(&wq_pool_mutex);
5886	}
5887	}
5888
5889	/* create default unbound and ordered wq attrs */
5890	for (i = 0; i < NR_STD_WORKER_POOLS; i++) {
5891	struct workqueue_attrs *attrs;
5892
5893	BUG_ON(!(attrs = alloc_workqueue_attrs()));
5894	attrs->nice = std_nice[i];
5895	unbound_std_wq_attrs[i] = attrs;
5896
5897	/*
5898	* An ordered wq should have only one pwq as ordering is
5899	* guaranteed by max_active which is enforced by pwqs.
5900	* Turn off NUMA so that dfl_pwq is used for all nodes.
5901	*/
5902	BUG_ON(!(attrs = alloc_workqueue_attrs()));
5903	attrs->nice = std_nice[i];
5904	attrs->no_numa = true;
5905	ordered_wq_attrs[i] = attrs;
5906	}
5907
5908	system_wq = alloc_workqueue("events", 0, 0);
5909	system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0);
5910	system_long_wq = alloc_workqueue("events_long", 0, 0);
5911	system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND,
5912	WQ_UNBOUND_MAX_ACTIVE);
5913	system_freezable_wq = alloc_workqueue("events_freezable",
5914	WQ_FREEZABLE, 0);
5915	system_power_efficient_wq = alloc_workqueue("events_power_efficient",
5916	WQ_POWER_EFFICIENT, 0);
5917	system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient",
5918	WQ_FREEZABLE \| WQ_POWER_EFFICIENT,
5919	0);
5920	BUG_ON(!system_wq \|\| !system_highpri_wq \|\| !system_long_wq \|\|
5921	!system_unbound_wq \|\| !system_freezable_wq \|\|
5922	!system_power_efficient_wq \|\|
5923	!system_freezable_power_efficient_wq);
5924
5925	return 0;
5926	}
5927
5928	/**
5929	* workqueue_init - bring workqueue subsystem fully online
5930	*
5931	* This is the latter half of two-staged workqueue subsystem initialization
5932	* and invoked as soon as kthreads can be created and scheduled.
5933	* Workqueues have been created and work items queued on them, but there
5934	* are no kworkers executing the work items yet. Populate the worker pools
5935	* with the initial workers and enable future kworker creations.
5936	*/
5937	int __init workqueue_init(void)
5938	{
5939	struct workqueue_struct *wq;
5940	struct worker_pool *pool;
5941	int cpu, bkt;
5942
5943	/*
5944	* It'd be simpler to initialize NUMA in workqueue_init_early() but
5945	* CPU to node mapping may not be available that early on some
5946	* archs such as power and arm64. As per-cpu pools created
5947	* previously could be missing node hint and unbound pools NUMA
5948	* affinity, fix them up.
5949	*
5950	* Also, while iterating workqueues, create rescuers if requested.
5951	*/
5952	wq_numa_init();
5953
5954	mutex_lock(&wq_pool_mutex);
5955
5956	for_each_possible_cpu(cpu) {
5957	for_each_cpu_worker_pool(pool, cpu) {
5958	pool->node = cpu_to_node(cpu);
5959	}
5960	}
5961
5962	list_for_each_entry(wq, &workqueues, list) {
5963	wq_update_unbound_numa(wq, smp_processor_id(), true);
5964	WARN(init_rescuer(wq),
5965	"workqueue: failed to create early rescuer for %s",
5966	wq->name);
5967	}
5968
5969	mutex_unlock(&wq_pool_mutex);
5970
5971	/* create the initial workers */
5972	for_each_online_cpu(cpu) {
5973	for_each_cpu_worker_pool(pool, cpu) {
5974	pool->flags &= ~POOL_DISASSOCIATED;
5975	BUG_ON(!create_worker(pool));
5976	}
5977	}
5978
5979	hash_for_each(unbound_pool_hash, bkt, pool, hash_node)
5980	BUG_ON(!create_worker(pool));
5981
5982	wq_online = true;
5983	wq_watchdog_init();
5984
5985	return 0;
5986	}