2 * kernel/workqueue.c - generic async execution with shared worker pool
4 * Copyright (C) 2002 Ingo Molnar
6 * Derived from the taskqueue/keventd code by:
7 * David Woodhouse <dwmw2@infradead.org>
9 * Kai Petzke <wpp@marie.physik.tu-berlin.de>
10 * Theodore Ts'o <tytso@mit.edu>
12 * Made to use alloc_percpu by Christoph Lameter.
14 * Copyright (C) 2010 SUSE Linux Products GmbH
15 * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
17 * This is the generic async execution mechanism. Work items as are
18 * executed in process context. The worker pool is shared and
19 * automatically managed. There is one worker pool for each CPU and
20 * one extra for works which are better served by workers which are
21 * not bound to any specific CPU.
23 * Please read Documentation/workqueue.txt for details.
26 #include <linux/export.h>
27 #include <linux/kernel.h>
28 #include <linux/sched.h>
29 #include <linux/init.h>
30 #include <linux/signal.h>
31 #include <linux/completion.h>
32 #include <linux/workqueue.h>
33 #include <linux/slab.h>
34 #include <linux/cpu.h>
35 #include <linux/notifier.h>
36 #include <linux/kthread.h>
37 #include <linux/hardirq.h>
38 #include <linux/mempolicy.h>
39 #include <linux/freezer.h>
40 #include <linux/kallsyms.h>
41 #include <linux/debug_locks.h>
42 #include <linux/lockdep.h>
43 #include <linux/idr.h>
45 #include "workqueue_sched.h"
51 * A bound gcwq is either associated or disassociated with its CPU.
52 * While associated (!DISASSOCIATED), all workers are bound to the
53 * CPU and none has %WORKER_UNBOUND set and concurrency management
56 * While DISASSOCIATED, the cpu may be offline and all workers have
57 * %WORKER_UNBOUND set and concurrency management disabled, and may
58 * be executing on any CPU. The gcwq behaves as an unbound one.
60 * Note that DISASSOCIATED can be flipped only while holding
61 * managership of all pools on the gcwq to avoid changing binding
62 * state while create_worker() is in progress.
64 GCWQ_DISASSOCIATED
= 1 << 0, /* cpu can't serve workers */
65 GCWQ_FREEZING
= 1 << 1, /* freeze in progress */
68 POOL_MANAGE_WORKERS
= 1 << 0, /* need to manage workers */
71 WORKER_STARTED
= 1 << 0, /* started */
72 WORKER_DIE
= 1 << 1, /* die die die */
73 WORKER_IDLE
= 1 << 2, /* is idle */
74 WORKER_PREP
= 1 << 3, /* preparing to run works */
75 WORKER_REBIND
= 1 << 5, /* mom is home, come back */
76 WORKER_CPU_INTENSIVE
= 1 << 6, /* cpu intensive */
77 WORKER_UNBOUND
= 1 << 7, /* worker is unbound */
79 WORKER_NOT_RUNNING
= WORKER_PREP
| WORKER_REBIND
| WORKER_UNBOUND
|
82 NR_WORKER_POOLS
= 2, /* # worker pools per gcwq */
84 BUSY_WORKER_HASH_ORDER
= 6, /* 64 pointers */
85 BUSY_WORKER_HASH_SIZE
= 1 << BUSY_WORKER_HASH_ORDER
,
86 BUSY_WORKER_HASH_MASK
= BUSY_WORKER_HASH_SIZE
- 1,
88 MAX_IDLE_WORKERS_RATIO
= 4, /* 1/4 of busy can be idle */
89 IDLE_WORKER_TIMEOUT
= 300 * HZ
, /* keep idle ones for 5 mins */
91 MAYDAY_INITIAL_TIMEOUT
= HZ
/ 100 >= 2 ? HZ
/ 100 : 2,
92 /* call for help after 10ms
94 MAYDAY_INTERVAL
= HZ
/ 10, /* and then every 100ms */
95 CREATE_COOLDOWN
= HZ
, /* time to breath after fail */
98 * Rescue workers are used only on emergencies and shared by
101 RESCUER_NICE_LEVEL
= -20,
102 HIGHPRI_NICE_LEVEL
= -20,
106 * Structure fields follow one of the following exclusion rules.
108 * I: Modifiable by initialization/destruction paths and read-only for
111 * P: Preemption protected. Disabling preemption is enough and should
112 * only be modified and accessed from the local cpu.
114 * L: gcwq->lock protected. Access with gcwq->lock held.
116 * X: During normal operation, modification requires gcwq->lock and
117 * should be done only from local cpu. Either disabling preemption
118 * on local cpu or grabbing gcwq->lock is enough for read access.
119 * If GCWQ_DISASSOCIATED is set, it's identical to L.
121 * F: wq->flush_mutex protected.
123 * W: workqueue_lock protected.
131 * The poor guys doing the actual heavy lifting. All on-duty workers
132 * are either serving the manager role, on idle list or on busy hash.
135 /* on idle list while idle, on busy hash table while busy */
137 struct list_head entry
; /* L: while idle */
138 struct hlist_node hentry
; /* L: while busy */
141 struct work_struct
*current_work
; /* L: work being processed */
142 struct cpu_workqueue_struct
*current_cwq
; /* L: current_work's cwq */
143 struct list_head scheduled
; /* L: scheduled works */
144 struct task_struct
*task
; /* I: worker task */
145 struct worker_pool
*pool
; /* I: the associated pool */
146 /* 64 bytes boundary on 64bit, 32 on 32bit */
147 unsigned long last_active
; /* L: last active timestamp */
148 unsigned int flags
; /* X: flags */
149 int id
; /* I: worker id */
151 /* for rebinding worker to CPU */
152 struct idle_rebind
*idle_rebind
; /* L: for idle worker */
153 struct work_struct rebind_work
; /* L: for busy worker */
157 struct global_cwq
*gcwq
; /* I: the owning gcwq */
158 unsigned int flags
; /* X: flags */
160 struct list_head worklist
; /* L: list of pending works */
161 int nr_workers
; /* L: total number of workers */
162 int nr_idle
; /* L: currently idle ones */
164 struct list_head idle_list
; /* X: list of idle workers */
165 struct timer_list idle_timer
; /* L: worker idle timeout */
166 struct timer_list mayday_timer
; /* L: SOS timer for workers */
168 struct mutex manager_mutex
; /* mutex manager should hold */
169 struct ida worker_ida
; /* L: for worker IDs */
173 * Global per-cpu workqueue. There's one and only one for each cpu
174 * and all works are queued and processed here regardless of their
178 spinlock_t lock
; /* the gcwq lock */
179 unsigned int cpu
; /* I: the associated cpu */
180 unsigned int flags
; /* L: GCWQ_* flags */
182 /* workers are chained either in busy_hash or pool idle_list */
183 struct hlist_head busy_hash
[BUSY_WORKER_HASH_SIZE
];
184 /* L: hash of busy workers */
186 struct worker_pool pools
[2]; /* normal and highpri pools */
188 wait_queue_head_t rebind_hold
; /* rebind hold wait */
189 } ____cacheline_aligned_in_smp
;
192 * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of
193 * work_struct->data are used for flags and thus cwqs need to be
194 * aligned at two's power of the number of flag bits.
196 struct cpu_workqueue_struct
{
197 struct worker_pool
*pool
; /* I: the associated pool */
198 struct workqueue_struct
*wq
; /* I: the owning workqueue */
199 int work_color
; /* L: current color */
200 int flush_color
; /* L: flushing color */
201 int nr_in_flight
[WORK_NR_COLORS
];
202 /* L: nr of in_flight works */
203 int nr_active
; /* L: nr of active works */
204 int max_active
; /* L: max active works */
205 struct list_head delayed_works
; /* L: delayed works */
209 * Structure used to wait for workqueue flush.
212 struct list_head list
; /* F: list of flushers */
213 int flush_color
; /* F: flush color waiting for */
214 struct completion done
; /* flush completion */
218 * All cpumasks are assumed to be always set on UP and thus can't be
219 * used to determine whether there's something to be done.
222 typedef cpumask_var_t mayday_mask_t
;
223 #define mayday_test_and_set_cpu(cpu, mask) \
224 cpumask_test_and_set_cpu((cpu), (mask))
225 #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask))
226 #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask))
227 #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp))
228 #define free_mayday_mask(mask) free_cpumask_var((mask))
230 typedef unsigned long mayday_mask_t
;
231 #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask))
232 #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask))
233 #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask))
234 #define alloc_mayday_mask(maskp, gfp) true
235 #define free_mayday_mask(mask) do { } while (0)
239 * The externally visible workqueue abstraction is an array of
240 * per-CPU workqueues:
242 struct workqueue_struct
{
243 unsigned int flags
; /* W: WQ_* flags */
245 struct cpu_workqueue_struct __percpu
*pcpu
;
246 struct cpu_workqueue_struct
*single
;
248 } cpu_wq
; /* I: cwq's */
249 struct list_head list
; /* W: list of all workqueues */
251 struct mutex flush_mutex
; /* protects wq flushing */
252 int work_color
; /* F: current work color */
253 int flush_color
; /* F: current flush color */
254 atomic_t nr_cwqs_to_flush
; /* flush in progress */
255 struct wq_flusher
*first_flusher
; /* F: first flusher */
256 struct list_head flusher_queue
; /* F: flush waiters */
257 struct list_head flusher_overflow
; /* F: flush overflow list */
259 mayday_mask_t mayday_mask
; /* cpus requesting rescue */
260 struct worker
*rescuer
; /* I: rescue worker */
262 int nr_drainers
; /* W: drain in progress */
263 int saved_max_active
; /* W: saved cwq max_active */
264 #ifdef CONFIG_LOCKDEP
265 struct lockdep_map lockdep_map
;
267 char name
[]; /* I: workqueue name */
270 struct workqueue_struct
*system_wq __read_mostly
;
271 struct workqueue_struct
*system_long_wq __read_mostly
;
272 struct workqueue_struct
*system_nrt_wq __read_mostly
;
273 struct workqueue_struct
*system_unbound_wq __read_mostly
;
274 struct workqueue_struct
*system_freezable_wq __read_mostly
;
275 struct workqueue_struct
*system_nrt_freezable_wq __read_mostly
;
276 EXPORT_SYMBOL_GPL(system_wq
);
277 EXPORT_SYMBOL_GPL(system_long_wq
);
278 EXPORT_SYMBOL_GPL(system_nrt_wq
);
279 EXPORT_SYMBOL_GPL(system_unbound_wq
);
280 EXPORT_SYMBOL_GPL(system_freezable_wq
);
281 EXPORT_SYMBOL_GPL(system_nrt_freezable_wq
);
283 #define CREATE_TRACE_POINTS
284 #include <trace/events/workqueue.h>
286 #define for_each_worker_pool(pool, gcwq) \
287 for ((pool) = &(gcwq)->pools[0]; \
288 (pool) < &(gcwq)->pools[NR_WORKER_POOLS]; (pool)++)
290 #define for_each_busy_worker(worker, i, pos, gcwq) \
291 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \
292 hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
294 static inline int __next_gcwq_cpu(int cpu
, const struct cpumask
*mask
,
297 if (cpu
< nr_cpu_ids
) {
299 cpu
= cpumask_next(cpu
, mask
);
300 if (cpu
< nr_cpu_ids
)
304 return WORK_CPU_UNBOUND
;
306 return WORK_CPU_NONE
;
309 static inline int __next_wq_cpu(int cpu
, const struct cpumask
*mask
,
310 struct workqueue_struct
*wq
)
312 return __next_gcwq_cpu(cpu
, mask
, !(wq
->flags
& WQ_UNBOUND
) ? 1 : 2);
318 * An extra gcwq is defined for an invalid cpu number
319 * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any
320 * specific CPU. The following iterators are similar to
321 * for_each_*_cpu() iterators but also considers the unbound gcwq.
323 * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND
324 * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND
325 * for_each_cwq_cpu() : possible CPUs for bound workqueues,
326 * WORK_CPU_UNBOUND for unbound workqueues
328 #define for_each_gcwq_cpu(cpu) \
329 for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \
330 (cpu) < WORK_CPU_NONE; \
331 (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3))
333 #define for_each_online_gcwq_cpu(cpu) \
334 for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \
335 (cpu) < WORK_CPU_NONE; \
336 (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3))
338 #define for_each_cwq_cpu(cpu, wq) \
339 for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \
340 (cpu) < WORK_CPU_NONE; \
341 (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq)))
343 #ifdef CONFIG_DEBUG_OBJECTS_WORK
345 static struct debug_obj_descr work_debug_descr
;
347 static void *work_debug_hint(void *addr
)
349 return ((struct work_struct
*) addr
)->func
;
353 * fixup_init is called when:
354 * - an active object is initialized
356 static int work_fixup_init(void *addr
, enum debug_obj_state state
)
358 struct work_struct
*work
= addr
;
361 case ODEBUG_STATE_ACTIVE
:
362 cancel_work_sync(work
);
363 debug_object_init(work
, &work_debug_descr
);
371 * fixup_activate is called when:
372 * - an active object is activated
373 * - an unknown object is activated (might be a statically initialized object)
375 static int work_fixup_activate(void *addr
, enum debug_obj_state state
)
377 struct work_struct
*work
= addr
;
381 case ODEBUG_STATE_NOTAVAILABLE
:
383 * This is not really a fixup. The work struct was
384 * statically initialized. We just make sure that it
385 * is tracked in the object tracker.
387 if (test_bit(WORK_STRUCT_STATIC_BIT
, work_data_bits(work
))) {
388 debug_object_init(work
, &work_debug_descr
);
389 debug_object_activate(work
, &work_debug_descr
);
395 case ODEBUG_STATE_ACTIVE
:
404 * fixup_free is called when:
405 * - an active object is freed
407 static int work_fixup_free(void *addr
, enum debug_obj_state state
)
409 struct work_struct
*work
= addr
;
412 case ODEBUG_STATE_ACTIVE
:
413 cancel_work_sync(work
);
414 debug_object_free(work
, &work_debug_descr
);
421 static struct debug_obj_descr work_debug_descr
= {
422 .name
= "work_struct",
423 .debug_hint
= work_debug_hint
,
424 .fixup_init
= work_fixup_init
,
425 .fixup_activate
= work_fixup_activate
,
426 .fixup_free
= work_fixup_free
,
429 static inline void debug_work_activate(struct work_struct
*work
)
431 debug_object_activate(work
, &work_debug_descr
);
434 static inline void debug_work_deactivate(struct work_struct
*work
)
436 debug_object_deactivate(work
, &work_debug_descr
);
439 void __init_work(struct work_struct
*work
, int onstack
)
442 debug_object_init_on_stack(work
, &work_debug_descr
);
444 debug_object_init(work
, &work_debug_descr
);
446 EXPORT_SYMBOL_GPL(__init_work
);
448 void destroy_work_on_stack(struct work_struct
*work
)
450 debug_object_free(work
, &work_debug_descr
);
452 EXPORT_SYMBOL_GPL(destroy_work_on_stack
);
455 static inline void debug_work_activate(struct work_struct
*work
) { }
456 static inline void debug_work_deactivate(struct work_struct
*work
) { }
459 /* Serializes the accesses to the list of workqueues. */
460 static DEFINE_SPINLOCK(workqueue_lock
);
461 static LIST_HEAD(workqueues
);
462 static bool workqueue_freezing
; /* W: have wqs started freezing? */
465 * The almighty global cpu workqueues. nr_running is the only field
466 * which is expected to be used frequently by other cpus via
467 * try_to_wake_up(). Put it in a separate cacheline.
469 static DEFINE_PER_CPU(struct global_cwq
, global_cwq
);
470 static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t
, pool_nr_running
[NR_WORKER_POOLS
]);
473 * Global cpu workqueue and nr_running counter for unbound gcwq. The
474 * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its
475 * workers have WORKER_UNBOUND set.
477 static struct global_cwq unbound_global_cwq
;
478 static atomic_t unbound_pool_nr_running
[NR_WORKER_POOLS
] = {
479 [0 ... NR_WORKER_POOLS
- 1] = ATOMIC_INIT(0), /* always 0 */
482 static int worker_thread(void *__worker
);
484 static int worker_pool_pri(struct worker_pool
*pool
)
486 return pool
- pool
->gcwq
->pools
;
489 static struct global_cwq
*get_gcwq(unsigned int cpu
)
491 if (cpu
!= WORK_CPU_UNBOUND
)
492 return &per_cpu(global_cwq
, cpu
);
494 return &unbound_global_cwq
;
497 static atomic_t
*get_pool_nr_running(struct worker_pool
*pool
)
499 int cpu
= pool
->gcwq
->cpu
;
500 int idx
= worker_pool_pri(pool
);
502 if (cpu
!= WORK_CPU_UNBOUND
)
503 return &per_cpu(pool_nr_running
, cpu
)[idx
];
505 return &unbound_pool_nr_running
[idx
];
508 static struct cpu_workqueue_struct
*get_cwq(unsigned int cpu
,
509 struct workqueue_struct
*wq
)
511 if (!(wq
->flags
& WQ_UNBOUND
)) {
512 if (likely(cpu
< nr_cpu_ids
))
513 return per_cpu_ptr(wq
->cpu_wq
.pcpu
, cpu
);
514 } else if (likely(cpu
== WORK_CPU_UNBOUND
))
515 return wq
->cpu_wq
.single
;
519 static unsigned int work_color_to_flags(int color
)
521 return color
<< WORK_STRUCT_COLOR_SHIFT
;
524 static int get_work_color(struct work_struct
*work
)
526 return (*work_data_bits(work
) >> WORK_STRUCT_COLOR_SHIFT
) &
527 ((1 << WORK_STRUCT_COLOR_BITS
) - 1);
530 static int work_next_color(int color
)
532 return (color
+ 1) % WORK_NR_COLORS
;
536 * A work's data points to the cwq with WORK_STRUCT_CWQ set while the
537 * work is on queue. Once execution starts, WORK_STRUCT_CWQ is
538 * cleared and the work data contains the cpu number it was last on.
540 * set_work_{cwq|cpu}() and clear_work_data() can be used to set the
541 * cwq, cpu or clear work->data. These functions should only be
542 * called while the work is owned - ie. while the PENDING bit is set.
544 * get_work_[g]cwq() can be used to obtain the gcwq or cwq
545 * corresponding to a work. gcwq is available once the work has been
546 * queued anywhere after initialization. cwq is available only from
547 * queueing until execution starts.
549 static inline void set_work_data(struct work_struct
*work
, unsigned long data
,
552 BUG_ON(!work_pending(work
));
553 atomic_long_set(&work
->data
, data
| flags
| work_static(work
));
556 static void set_work_cwq(struct work_struct
*work
,
557 struct cpu_workqueue_struct
*cwq
,
558 unsigned long extra_flags
)
560 set_work_data(work
, (unsigned long)cwq
,
561 WORK_STRUCT_PENDING
| WORK_STRUCT_CWQ
| extra_flags
);
564 static void set_work_cpu(struct work_struct
*work
, unsigned int cpu
)
566 set_work_data(work
, cpu
<< WORK_STRUCT_FLAG_BITS
, WORK_STRUCT_PENDING
);
569 static void clear_work_data(struct work_struct
*work
)
571 set_work_data(work
, WORK_STRUCT_NO_CPU
, 0);
574 static struct cpu_workqueue_struct
*get_work_cwq(struct work_struct
*work
)
576 unsigned long data
= atomic_long_read(&work
->data
);
578 if (data
& WORK_STRUCT_CWQ
)
579 return (void *)(data
& WORK_STRUCT_WQ_DATA_MASK
);
584 static struct global_cwq
*get_work_gcwq(struct work_struct
*work
)
586 unsigned long data
= atomic_long_read(&work
->data
);
589 if (data
& WORK_STRUCT_CWQ
)
590 return ((struct cpu_workqueue_struct
*)
591 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
->gcwq
;
593 cpu
= data
>> WORK_STRUCT_FLAG_BITS
;
594 if (cpu
== WORK_CPU_NONE
)
597 BUG_ON(cpu
>= nr_cpu_ids
&& cpu
!= WORK_CPU_UNBOUND
);
598 return get_gcwq(cpu
);
602 * Policy functions. These define the policies on how the global worker
603 * pools are managed. Unless noted otherwise, these functions assume that
604 * they're being called with gcwq->lock held.
607 static bool __need_more_worker(struct worker_pool
*pool
)
609 return !atomic_read(get_pool_nr_running(pool
));
613 * Need to wake up a worker? Called from anything but currently
616 * Note that, because unbound workers never contribute to nr_running, this
617 * function will always return %true for unbound gcwq as long as the
618 * worklist isn't empty.
620 static bool need_more_worker(struct worker_pool
*pool
)
622 return !list_empty(&pool
->worklist
) && __need_more_worker(pool
);
625 /* Can I start working? Called from busy but !running workers. */
626 static bool may_start_working(struct worker_pool
*pool
)
628 return pool
->nr_idle
;
631 /* Do I need to keep working? Called from currently running workers. */
632 static bool keep_working(struct worker_pool
*pool
)
634 atomic_t
*nr_running
= get_pool_nr_running(pool
);
636 return !list_empty(&pool
->worklist
) && atomic_read(nr_running
) <= 1;
639 /* Do we need a new worker? Called from manager. */
640 static bool need_to_create_worker(struct worker_pool
*pool
)
642 return need_more_worker(pool
) && !may_start_working(pool
);
645 /* Do I need to be the manager? */
646 static bool need_to_manage_workers(struct worker_pool
*pool
)
648 return need_to_create_worker(pool
) ||
649 (pool
->flags
& POOL_MANAGE_WORKERS
);
652 /* Do we have too many workers and should some go away? */
653 static bool too_many_workers(struct worker_pool
*pool
)
655 bool managing
= mutex_is_locked(&pool
->manager_mutex
);
656 int nr_idle
= pool
->nr_idle
+ managing
; /* manager is considered idle */
657 int nr_busy
= pool
->nr_workers
- nr_idle
;
659 return nr_idle
> 2 && (nr_idle
- 2) * MAX_IDLE_WORKERS_RATIO
>= nr_busy
;
666 /* Return the first worker. Safe with preemption disabled */
667 static struct worker
*first_worker(struct worker_pool
*pool
)
669 if (unlikely(list_empty(&pool
->idle_list
)))
672 return list_first_entry(&pool
->idle_list
, struct worker
, entry
);
676 * wake_up_worker - wake up an idle worker
677 * @pool: worker pool to wake worker from
679 * Wake up the first idle worker of @pool.
682 * spin_lock_irq(gcwq->lock).
684 static void wake_up_worker(struct worker_pool
*pool
)
686 struct worker
*worker
= first_worker(pool
);
689 wake_up_process(worker
->task
);
693 * wq_worker_waking_up - a worker is waking up
694 * @task: task waking up
695 * @cpu: CPU @task is waking up to
697 * This function is called during try_to_wake_up() when a worker is
701 * spin_lock_irq(rq->lock)
703 void wq_worker_waking_up(struct task_struct
*task
, unsigned int cpu
)
705 struct worker
*worker
= kthread_data(task
);
707 if (!(worker
->flags
& WORKER_NOT_RUNNING
))
708 atomic_inc(get_pool_nr_running(worker
->pool
));
712 * wq_worker_sleeping - a worker is going to sleep
713 * @task: task going to sleep
714 * @cpu: CPU in question, must be the current CPU number
716 * This function is called during schedule() when a busy worker is
717 * going to sleep. Worker on the same cpu can be woken up by
718 * returning pointer to its task.
721 * spin_lock_irq(rq->lock)
724 * Worker task on @cpu to wake up, %NULL if none.
726 struct task_struct
*wq_worker_sleeping(struct task_struct
*task
,
729 struct worker
*worker
= kthread_data(task
), *to_wakeup
= NULL
;
730 struct worker_pool
*pool
= worker
->pool
;
731 atomic_t
*nr_running
= get_pool_nr_running(pool
);
733 if (worker
->flags
& WORKER_NOT_RUNNING
)
736 /* this can only happen on the local cpu */
737 BUG_ON(cpu
!= raw_smp_processor_id());
740 * The counterpart of the following dec_and_test, implied mb,
741 * worklist not empty test sequence is in insert_work().
742 * Please read comment there.
744 * NOT_RUNNING is clear. This means that we're bound to and
745 * running on the local cpu w/ rq lock held and preemption
746 * disabled, which in turn means that none else could be
747 * manipulating idle_list, so dereferencing idle_list without gcwq
750 if (atomic_dec_and_test(nr_running
) && !list_empty(&pool
->worklist
))
751 to_wakeup
= first_worker(pool
);
752 return to_wakeup
? to_wakeup
->task
: NULL
;
756 * worker_set_flags - set worker flags and adjust nr_running accordingly
758 * @flags: flags to set
759 * @wakeup: wakeup an idle worker if necessary
761 * Set @flags in @worker->flags and adjust nr_running accordingly. If
762 * nr_running becomes zero and @wakeup is %true, an idle worker is
766 * spin_lock_irq(gcwq->lock)
768 static inline void worker_set_flags(struct worker
*worker
, unsigned int flags
,
771 struct worker_pool
*pool
= worker
->pool
;
773 WARN_ON_ONCE(worker
->task
!= current
);
776 * If transitioning into NOT_RUNNING, adjust nr_running and
777 * wake up an idle worker as necessary if requested by
780 if ((flags
& WORKER_NOT_RUNNING
) &&
781 !(worker
->flags
& WORKER_NOT_RUNNING
)) {
782 atomic_t
*nr_running
= get_pool_nr_running(pool
);
785 if (atomic_dec_and_test(nr_running
) &&
786 !list_empty(&pool
->worklist
))
787 wake_up_worker(pool
);
789 atomic_dec(nr_running
);
792 worker
->flags
|= flags
;
796 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
798 * @flags: flags to clear
800 * Clear @flags in @worker->flags and adjust nr_running accordingly.
803 * spin_lock_irq(gcwq->lock)
805 static inline void worker_clr_flags(struct worker
*worker
, unsigned int flags
)
807 struct worker_pool
*pool
= worker
->pool
;
808 unsigned int oflags
= worker
->flags
;
810 WARN_ON_ONCE(worker
->task
!= current
);
812 worker
->flags
&= ~flags
;
815 * If transitioning out of NOT_RUNNING, increment nr_running. Note
816 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
817 * of multiple flags, not a single flag.
819 if ((flags
& WORKER_NOT_RUNNING
) && (oflags
& WORKER_NOT_RUNNING
))
820 if (!(worker
->flags
& WORKER_NOT_RUNNING
))
821 atomic_inc(get_pool_nr_running(pool
));
825 * busy_worker_head - return the busy hash head for a work
826 * @gcwq: gcwq of interest
827 * @work: work to be hashed
829 * Return hash head of @gcwq for @work.
832 * spin_lock_irq(gcwq->lock).
835 * Pointer to the hash head.
837 static struct hlist_head
*busy_worker_head(struct global_cwq
*gcwq
,
838 struct work_struct
*work
)
840 const int base_shift
= ilog2(sizeof(struct work_struct
));
841 unsigned long v
= (unsigned long)work
;
843 /* simple shift and fold hash, do we need something better? */
845 v
+= v
>> BUSY_WORKER_HASH_ORDER
;
846 v
&= BUSY_WORKER_HASH_MASK
;
848 return &gcwq
->busy_hash
[v
];
852 * __find_worker_executing_work - find worker which is executing a work
853 * @gcwq: gcwq of interest
854 * @bwh: hash head as returned by busy_worker_head()
855 * @work: work to find worker for
857 * Find a worker which is executing @work on @gcwq. @bwh should be
858 * the hash head obtained by calling busy_worker_head() with the same
862 * spin_lock_irq(gcwq->lock).
865 * Pointer to worker which is executing @work if found, NULL
868 static struct worker
*__find_worker_executing_work(struct global_cwq
*gcwq
,
869 struct hlist_head
*bwh
,
870 struct work_struct
*work
)
872 struct worker
*worker
;
873 struct hlist_node
*tmp
;
875 hlist_for_each_entry(worker
, tmp
, bwh
, hentry
)
876 if (worker
->current_work
== work
)
882 * find_worker_executing_work - find worker which is executing a work
883 * @gcwq: gcwq of interest
884 * @work: work to find worker for
886 * Find a worker which is executing @work on @gcwq. This function is
887 * identical to __find_worker_executing_work() except that this
888 * function calculates @bwh itself.
891 * spin_lock_irq(gcwq->lock).
894 * Pointer to worker which is executing @work if found, NULL
897 static struct worker
*find_worker_executing_work(struct global_cwq
*gcwq
,
898 struct work_struct
*work
)
900 return __find_worker_executing_work(gcwq
, busy_worker_head(gcwq
, work
),
905 * insert_work - insert a work into gcwq
906 * @cwq: cwq @work belongs to
907 * @work: work to insert
908 * @head: insertion point
909 * @extra_flags: extra WORK_STRUCT_* flags to set
911 * Insert @work which belongs to @cwq into @gcwq after @head.
912 * @extra_flags is or'd to work_struct flags.
915 * spin_lock_irq(gcwq->lock).
917 static void insert_work(struct cpu_workqueue_struct
*cwq
,
918 struct work_struct
*work
, struct list_head
*head
,
919 unsigned int extra_flags
)
921 struct worker_pool
*pool
= cwq
->pool
;
923 /* we own @work, set data and link */
924 set_work_cwq(work
, cwq
, extra_flags
);
927 * Ensure that we get the right work->data if we see the
928 * result of list_add() below, see try_to_grab_pending().
932 list_add_tail(&work
->entry
, head
);
935 * Ensure either worker_sched_deactivated() sees the above
936 * list_add_tail() or we see zero nr_running to avoid workers
937 * lying around lazily while there are works to be processed.
941 if (__need_more_worker(pool
))
942 wake_up_worker(pool
);
946 * Test whether @work is being queued from another work executing on the
947 * same workqueue. This is rather expensive and should only be used from
950 static bool is_chained_work(struct workqueue_struct
*wq
)
955 for_each_gcwq_cpu(cpu
) {
956 struct global_cwq
*gcwq
= get_gcwq(cpu
);
957 struct worker
*worker
;
958 struct hlist_node
*pos
;
961 spin_lock_irqsave(&gcwq
->lock
, flags
);
962 for_each_busy_worker(worker
, i
, pos
, gcwq
) {
963 if (worker
->task
!= current
)
965 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
967 * I'm @worker, no locking necessary. See if @work
968 * is headed to the same workqueue.
970 return worker
->current_cwq
->wq
== wq
;
972 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
977 static void __queue_work(unsigned int cpu
, struct workqueue_struct
*wq
,
978 struct work_struct
*work
)
980 struct global_cwq
*gcwq
;
981 struct cpu_workqueue_struct
*cwq
;
982 struct list_head
*worklist
;
983 unsigned int work_flags
;
986 debug_work_activate(work
);
988 /* if dying, only works from the same workqueue are allowed */
989 if (unlikely(wq
->flags
& WQ_DRAINING
) &&
990 WARN_ON_ONCE(!is_chained_work(wq
)))
993 /* determine gcwq to use */
994 if (!(wq
->flags
& WQ_UNBOUND
)) {
995 struct global_cwq
*last_gcwq
;
997 if (unlikely(cpu
== WORK_CPU_UNBOUND
))
998 cpu
= raw_smp_processor_id();
1001 * It's multi cpu. If @wq is non-reentrant and @work
1002 * was previously on a different cpu, it might still
1003 * be running there, in which case the work needs to
1004 * be queued on that cpu to guarantee non-reentrance.
1006 gcwq
= get_gcwq(cpu
);
1007 if (wq
->flags
& WQ_NON_REENTRANT
&&
1008 (last_gcwq
= get_work_gcwq(work
)) && last_gcwq
!= gcwq
) {
1009 struct worker
*worker
;
1011 spin_lock_irqsave(&last_gcwq
->lock
, flags
);
1013 worker
= find_worker_executing_work(last_gcwq
, work
);
1015 if (worker
&& worker
->current_cwq
->wq
== wq
)
1018 /* meh... not running there, queue here */
1019 spin_unlock_irqrestore(&last_gcwq
->lock
, flags
);
1020 spin_lock_irqsave(&gcwq
->lock
, flags
);
1023 spin_lock_irqsave(&gcwq
->lock
, flags
);
1025 gcwq
= get_gcwq(WORK_CPU_UNBOUND
);
1026 spin_lock_irqsave(&gcwq
->lock
, flags
);
1029 /* gcwq determined, get cwq and queue */
1030 cwq
= get_cwq(gcwq
->cpu
, wq
);
1031 trace_workqueue_queue_work(cpu
, cwq
, work
);
1033 if (WARN_ON(!list_empty(&work
->entry
))) {
1034 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
1038 cwq
->nr_in_flight
[cwq
->work_color
]++;
1039 work_flags
= work_color_to_flags(cwq
->work_color
);
1041 if (likely(cwq
->nr_active
< cwq
->max_active
)) {
1042 trace_workqueue_activate_work(work
);
1044 worklist
= &cwq
->pool
->worklist
;
1046 work_flags
|= WORK_STRUCT_DELAYED
;
1047 worklist
= &cwq
->delayed_works
;
1050 insert_work(cwq
, work
, worklist
, work_flags
);
1052 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
1056 * queue_work - queue work on a workqueue
1057 * @wq: workqueue to use
1058 * @work: work to queue
1060 * Returns 0 if @work was already on a queue, non-zero otherwise.
1062 * We queue the work to the CPU on which it was submitted, but if the CPU dies
1063 * it can be processed by another CPU.
1065 int queue_work(struct workqueue_struct
*wq
, struct work_struct
*work
)
1069 ret
= queue_work_on(get_cpu(), wq
, work
);
1074 EXPORT_SYMBOL_GPL(queue_work
);
1077 * queue_work_on - queue work on specific cpu
1078 * @cpu: CPU number to execute work on
1079 * @wq: workqueue to use
1080 * @work: work to queue
1082 * Returns 0 if @work was already on a queue, non-zero otherwise.
1084 * We queue the work to a specific CPU, the caller must ensure it
1088 queue_work_on(int cpu
, struct workqueue_struct
*wq
, struct work_struct
*work
)
1092 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1093 __queue_work(cpu
, wq
, work
);
1098 EXPORT_SYMBOL_GPL(queue_work_on
);
1100 static void delayed_work_timer_fn(unsigned long __data
)
1102 struct delayed_work
*dwork
= (struct delayed_work
*)__data
;
1103 struct cpu_workqueue_struct
*cwq
= get_work_cwq(&dwork
->work
);
1105 __queue_work(smp_processor_id(), cwq
->wq
, &dwork
->work
);
1109 * queue_delayed_work - queue work on a workqueue after delay
1110 * @wq: workqueue to use
1111 * @dwork: delayable work to queue
1112 * @delay: number of jiffies to wait before queueing
1114 * Returns 0 if @work was already on a queue, non-zero otherwise.
1116 int queue_delayed_work(struct workqueue_struct
*wq
,
1117 struct delayed_work
*dwork
, unsigned long delay
)
1120 return queue_work(wq
, &dwork
->work
);
1122 return queue_delayed_work_on(-1, wq
, dwork
, delay
);
1124 EXPORT_SYMBOL_GPL(queue_delayed_work
);
1127 * queue_delayed_work_on - queue work on specific CPU after delay
1128 * @cpu: CPU number to execute work on
1129 * @wq: workqueue to use
1130 * @dwork: work to queue
1131 * @delay: number of jiffies to wait before queueing
1133 * Returns 0 if @work was already on a queue, non-zero otherwise.
1135 int queue_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1136 struct delayed_work
*dwork
, unsigned long delay
)
1139 struct timer_list
*timer
= &dwork
->timer
;
1140 struct work_struct
*work
= &dwork
->work
;
1142 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1145 BUG_ON(timer_pending(timer
));
1146 BUG_ON(!list_empty(&work
->entry
));
1148 timer_stats_timer_set_start_info(&dwork
->timer
);
1151 * This stores cwq for the moment, for the timer_fn.
1152 * Note that the work's gcwq is preserved to allow
1153 * reentrance detection for delayed works.
1155 if (!(wq
->flags
& WQ_UNBOUND
)) {
1156 struct global_cwq
*gcwq
= get_work_gcwq(work
);
1158 if (gcwq
&& gcwq
->cpu
!= WORK_CPU_UNBOUND
)
1161 lcpu
= raw_smp_processor_id();
1163 lcpu
= WORK_CPU_UNBOUND
;
1165 set_work_cwq(work
, get_cwq(lcpu
, wq
), 0);
1167 timer
->expires
= jiffies
+ delay
;
1168 timer
->data
= (unsigned long)dwork
;
1169 timer
->function
= delayed_work_timer_fn
;
1171 if (unlikely(cpu
>= 0))
1172 add_timer_on(timer
, cpu
);
1179 EXPORT_SYMBOL_GPL(queue_delayed_work_on
);
1182 * worker_enter_idle - enter idle state
1183 * @worker: worker which is entering idle state
1185 * @worker is entering idle state. Update stats and idle timer if
1189 * spin_lock_irq(gcwq->lock).
1191 static void worker_enter_idle(struct worker
*worker
)
1193 struct worker_pool
*pool
= worker
->pool
;
1194 struct global_cwq
*gcwq
= pool
->gcwq
;
1196 BUG_ON(worker
->flags
& WORKER_IDLE
);
1197 BUG_ON(!list_empty(&worker
->entry
) &&
1198 (worker
->hentry
.next
|| worker
->hentry
.pprev
));
1200 /* can't use worker_set_flags(), also called from start_worker() */
1201 worker
->flags
|= WORKER_IDLE
;
1203 worker
->last_active
= jiffies
;
1205 /* idle_list is LIFO */
1206 list_add(&worker
->entry
, &pool
->idle_list
);
1208 if (too_many_workers(pool
) && !timer_pending(&pool
->idle_timer
))
1209 mod_timer(&pool
->idle_timer
, jiffies
+ IDLE_WORKER_TIMEOUT
);
1212 * Sanity check nr_running. Because gcwq_unbind_fn() releases
1213 * gcwq->lock between setting %WORKER_UNBOUND and zapping
1214 * nr_running, the warning may trigger spuriously. Check iff
1215 * unbind is not in progress.
1217 WARN_ON_ONCE(!(gcwq
->flags
& GCWQ_DISASSOCIATED
) &&
1218 pool
->nr_workers
== pool
->nr_idle
&&
1219 atomic_read(get_pool_nr_running(pool
)));
1223 * worker_leave_idle - leave idle state
1224 * @worker: worker which is leaving idle state
1226 * @worker is leaving idle state. Update stats.
1229 * spin_lock_irq(gcwq->lock).
1231 static void worker_leave_idle(struct worker
*worker
)
1233 struct worker_pool
*pool
= worker
->pool
;
1235 BUG_ON(!(worker
->flags
& WORKER_IDLE
));
1236 worker_clr_flags(worker
, WORKER_IDLE
);
1238 list_del_init(&worker
->entry
);
1242 * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq
1245 * Works which are scheduled while the cpu is online must at least be
1246 * scheduled to a worker which is bound to the cpu so that if they are
1247 * flushed from cpu callbacks while cpu is going down, they are
1248 * guaranteed to execute on the cpu.
1250 * This function is to be used by rogue workers and rescuers to bind
1251 * themselves to the target cpu and may race with cpu going down or
1252 * coming online. kthread_bind() can't be used because it may put the
1253 * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
1254 * verbatim as it's best effort and blocking and gcwq may be
1255 * [dis]associated in the meantime.
1257 * This function tries set_cpus_allowed() and locks gcwq and verifies the
1258 * binding against %GCWQ_DISASSOCIATED which is set during
1259 * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker
1260 * enters idle state or fetches works without dropping lock, it can
1261 * guarantee the scheduling requirement described in the first paragraph.
1264 * Might sleep. Called without any lock but returns with gcwq->lock
1268 * %true if the associated gcwq is online (@worker is successfully
1269 * bound), %false if offline.
1271 static bool worker_maybe_bind_and_lock(struct worker
*worker
)
1272 __acquires(&gcwq
->lock
)
1274 struct global_cwq
*gcwq
= worker
->pool
->gcwq
;
1275 struct task_struct
*task
= worker
->task
;
1279 * The following call may fail, succeed or succeed
1280 * without actually migrating the task to the cpu if
1281 * it races with cpu hotunplug operation. Verify
1282 * against GCWQ_DISASSOCIATED.
1284 if (!(gcwq
->flags
& GCWQ_DISASSOCIATED
))
1285 set_cpus_allowed_ptr(task
, get_cpu_mask(gcwq
->cpu
));
1287 spin_lock_irq(&gcwq
->lock
);
1288 if (gcwq
->flags
& GCWQ_DISASSOCIATED
)
1290 if (task_cpu(task
) == gcwq
->cpu
&&
1291 cpumask_equal(¤t
->cpus_allowed
,
1292 get_cpu_mask(gcwq
->cpu
)))
1294 spin_unlock_irq(&gcwq
->lock
);
1297 * We've raced with CPU hot[un]plug. Give it a breather
1298 * and retry migration. cond_resched() is required here;
1299 * otherwise, we might deadlock against cpu_stop trying to
1300 * bring down the CPU on non-preemptive kernel.
1307 struct idle_rebind
{
1308 int cnt
; /* # workers to be rebound */
1309 struct completion done
; /* all workers rebound */
1313 * Rebind an idle @worker to its CPU. During CPU onlining, this has to
1314 * happen synchronously for idle workers. worker_thread() will test
1315 * %WORKER_REBIND before leaving idle and call this function.
1317 static void idle_worker_rebind(struct worker
*worker
)
1319 struct global_cwq
*gcwq
= worker
->pool
->gcwq
;
1321 /* CPU must be online at this point */
1322 WARN_ON(!worker_maybe_bind_and_lock(worker
));
1323 if (!--worker
->idle_rebind
->cnt
)
1324 complete(&worker
->idle_rebind
->done
);
1325 spin_unlock_irq(&worker
->pool
->gcwq
->lock
);
1327 /* we did our part, wait for rebind_workers() to finish up */
1328 wait_event(gcwq
->rebind_hold
, !(worker
->flags
& WORKER_REBIND
));
1331 * rebind_workers() shouldn't finish until all workers passed the
1332 * above WORKER_REBIND wait. Tell it when done.
1334 spin_lock_irq(&worker
->pool
->gcwq
->lock
);
1335 if (!--worker
->idle_rebind
->cnt
)
1336 complete(&worker
->idle_rebind
->done
);
1337 spin_unlock_irq(&worker
->pool
->gcwq
->lock
);
1341 * Function for @worker->rebind.work used to rebind unbound busy workers to
1342 * the associated cpu which is coming back online. This is scheduled by
1343 * cpu up but can race with other cpu hotplug operations and may be
1344 * executed twice without intervening cpu down.
1346 static void busy_worker_rebind_fn(struct work_struct
*work
)
1348 struct worker
*worker
= container_of(work
, struct worker
, rebind_work
);
1349 struct global_cwq
*gcwq
= worker
->pool
->gcwq
;
1351 if (worker_maybe_bind_and_lock(worker
))
1352 worker_clr_flags(worker
, WORKER_REBIND
);
1354 spin_unlock_irq(&gcwq
->lock
);
1358 * rebind_workers - rebind all workers of a gcwq to the associated CPU
1359 * @gcwq: gcwq of interest
1361 * @gcwq->cpu is coming online. Rebind all workers to the CPU. Rebinding
1362 * is different for idle and busy ones.
1364 * The idle ones should be rebound synchronously and idle rebinding should
1365 * be complete before any worker starts executing work items with
1366 * concurrency management enabled; otherwise, scheduler may oops trying to
1367 * wake up non-local idle worker from wq_worker_sleeping().
1369 * This is achieved by repeatedly requesting rebinding until all idle
1370 * workers are known to have been rebound under @gcwq->lock and holding all
1371 * idle workers from becoming busy until idle rebinding is complete.
1373 * Once idle workers are rebound, busy workers can be rebound as they
1374 * finish executing their current work items. Queueing the rebind work at
1375 * the head of their scheduled lists is enough. Note that nr_running will
1376 * be properbly bumped as busy workers rebind.
1378 * On return, all workers are guaranteed to either be bound or have rebind
1379 * work item scheduled.
1381 static void rebind_workers(struct global_cwq
*gcwq
)
1382 __releases(&gcwq
->lock
) __acquires(&gcwq
->lock
)
1384 struct idle_rebind idle_rebind
;
1385 struct worker_pool
*pool
;
1386 struct worker
*worker
;
1387 struct hlist_node
*pos
;
1390 lockdep_assert_held(&gcwq
->lock
);
1392 for_each_worker_pool(pool
, gcwq
)
1393 lockdep_assert_held(&pool
->manager_mutex
);
1396 * Rebind idle workers. Interlocked both ways. We wait for
1397 * workers to rebind via @idle_rebind.done. Workers will wait for
1398 * us to finish up by watching %WORKER_REBIND.
1400 init_completion(&idle_rebind
.done
);
1402 idle_rebind
.cnt
= 1;
1403 INIT_COMPLETION(idle_rebind
.done
);
1405 /* set REBIND and kick idle ones, we'll wait for these later */
1406 for_each_worker_pool(pool
, gcwq
) {
1407 list_for_each_entry(worker
, &pool
->idle_list
, entry
) {
1408 unsigned long worker_flags
= worker
->flags
;
1410 if (worker
->flags
& WORKER_REBIND
)
1413 /* morph UNBOUND to REBIND atomically */
1414 worker_flags
&= ~WORKER_UNBOUND
;
1415 worker_flags
|= WORKER_REBIND
;
1416 ACCESS_ONCE(worker
->flags
) = worker_flags
;
1419 worker
->idle_rebind
= &idle_rebind
;
1421 /* worker_thread() will call idle_worker_rebind() */
1422 wake_up_process(worker
->task
);
1426 if (--idle_rebind
.cnt
) {
1427 spin_unlock_irq(&gcwq
->lock
);
1428 wait_for_completion(&idle_rebind
.done
);
1429 spin_lock_irq(&gcwq
->lock
);
1430 /* busy ones might have become idle while waiting, retry */
1434 /* all idle workers are rebound, rebind busy workers */
1435 for_each_busy_worker(worker
, i
, pos
, gcwq
) {
1436 struct work_struct
*rebind_work
= &worker
->rebind_work
;
1437 unsigned long worker_flags
= worker
->flags
;
1439 /* morph UNBOUND to REBIND atomically */
1440 worker_flags
&= ~WORKER_UNBOUND
;
1441 worker_flags
|= WORKER_REBIND
;
1442 ACCESS_ONCE(worker
->flags
) = worker_flags
;
1444 if (test_and_set_bit(WORK_STRUCT_PENDING_BIT
,
1445 work_data_bits(rebind_work
)))
1448 /* wq doesn't matter, use the default one */
1449 debug_work_activate(rebind_work
);
1450 insert_work(get_cwq(gcwq
->cpu
, system_wq
), rebind_work
,
1451 worker
->scheduled
.next
,
1452 work_color_to_flags(WORK_NO_COLOR
));
1456 * All idle workers are rebound and waiting for %WORKER_REBIND to
1457 * be cleared inside idle_worker_rebind(). Clear and release.
1458 * Clearing %WORKER_REBIND from this foreign context is safe
1459 * because these workers are still guaranteed to be idle.
1461 * We need to make sure all idle workers passed WORKER_REBIND wait
1462 * in idle_worker_rebind() before returning; otherwise, workers can
1463 * get stuck at the wait if hotplug cycle repeats.
1465 idle_rebind
.cnt
= 1;
1466 INIT_COMPLETION(idle_rebind
.done
);
1468 for_each_worker_pool(pool
, gcwq
) {
1469 list_for_each_entry(worker
, &pool
->idle_list
, entry
) {
1470 worker
->flags
&= ~WORKER_REBIND
;
1475 wake_up_all(&gcwq
->rebind_hold
);
1477 if (--idle_rebind
.cnt
) {
1478 spin_unlock_irq(&gcwq
->lock
);
1479 wait_for_completion(&idle_rebind
.done
);
1480 spin_lock_irq(&gcwq
->lock
);
1484 static struct worker
*alloc_worker(void)
1486 struct worker
*worker
;
1488 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
1490 INIT_LIST_HEAD(&worker
->entry
);
1491 INIT_LIST_HEAD(&worker
->scheduled
);
1492 INIT_WORK(&worker
->rebind_work
, busy_worker_rebind_fn
);
1493 /* on creation a worker is in !idle && prep state */
1494 worker
->flags
= WORKER_PREP
;
1500 * create_worker - create a new workqueue worker
1501 * @pool: pool the new worker will belong to
1503 * Create a new worker which is bound to @pool. The returned worker
1504 * can be started by calling start_worker() or destroyed using
1508 * Might sleep. Does GFP_KERNEL allocations.
1511 * Pointer to the newly created worker.
1513 static struct worker
*create_worker(struct worker_pool
*pool
)
1515 struct global_cwq
*gcwq
= pool
->gcwq
;
1516 const char *pri
= worker_pool_pri(pool
) ? "H" : "";
1517 struct worker
*worker
= NULL
;
1520 spin_lock_irq(&gcwq
->lock
);
1521 while (ida_get_new(&pool
->worker_ida
, &id
)) {
1522 spin_unlock_irq(&gcwq
->lock
);
1523 if (!ida_pre_get(&pool
->worker_ida
, GFP_KERNEL
))
1525 spin_lock_irq(&gcwq
->lock
);
1527 spin_unlock_irq(&gcwq
->lock
);
1529 worker
= alloc_worker();
1533 worker
->pool
= pool
;
1536 if (gcwq
->cpu
!= WORK_CPU_UNBOUND
)
1537 worker
->task
= kthread_create_on_node(worker_thread
,
1538 worker
, cpu_to_node(gcwq
->cpu
),
1539 "kworker/%u:%d%s", gcwq
->cpu
, id
, pri
);
1541 worker
->task
= kthread_create(worker_thread
, worker
,
1542 "kworker/u:%d%s", id
, pri
);
1543 if (IS_ERR(worker
->task
))
1546 if (worker_pool_pri(pool
))
1547 set_user_nice(worker
->task
, HIGHPRI_NICE_LEVEL
);
1550 * Determine CPU binding of the new worker depending on
1551 * %GCWQ_DISASSOCIATED. The caller is responsible for ensuring the
1552 * flag remains stable across this function. See the comments
1553 * above the flag definition for details.
1555 * As an unbound worker may later become a regular one if CPU comes
1556 * online, make sure every worker has %PF_THREAD_BOUND set.
1558 if (!(gcwq
->flags
& GCWQ_DISASSOCIATED
)) {
1559 kthread_bind(worker
->task
, gcwq
->cpu
);
1561 worker
->task
->flags
|= PF_THREAD_BOUND
;
1562 worker
->flags
|= WORKER_UNBOUND
;
1568 spin_lock_irq(&gcwq
->lock
);
1569 ida_remove(&pool
->worker_ida
, id
);
1570 spin_unlock_irq(&gcwq
->lock
);
1577 * start_worker - start a newly created worker
1578 * @worker: worker to start
1580 * Make the gcwq aware of @worker and start it.
1583 * spin_lock_irq(gcwq->lock).
1585 static void start_worker(struct worker
*worker
)
1587 worker
->flags
|= WORKER_STARTED
;
1588 worker
->pool
->nr_workers
++;
1589 worker_enter_idle(worker
);
1590 wake_up_process(worker
->task
);
1594 * destroy_worker - destroy a workqueue worker
1595 * @worker: worker to be destroyed
1597 * Destroy @worker and adjust @gcwq stats accordingly.
1600 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1602 static void destroy_worker(struct worker
*worker
)
1604 struct worker_pool
*pool
= worker
->pool
;
1605 struct global_cwq
*gcwq
= pool
->gcwq
;
1606 int id
= worker
->id
;
1608 /* sanity check frenzy */
1609 BUG_ON(worker
->current_work
);
1610 BUG_ON(!list_empty(&worker
->scheduled
));
1612 if (worker
->flags
& WORKER_STARTED
)
1614 if (worker
->flags
& WORKER_IDLE
)
1617 list_del_init(&worker
->entry
);
1618 worker
->flags
|= WORKER_DIE
;
1620 spin_unlock_irq(&gcwq
->lock
);
1622 kthread_stop(worker
->task
);
1625 spin_lock_irq(&gcwq
->lock
);
1626 ida_remove(&pool
->worker_ida
, id
);
1629 static void idle_worker_timeout(unsigned long __pool
)
1631 struct worker_pool
*pool
= (void *)__pool
;
1632 struct global_cwq
*gcwq
= pool
->gcwq
;
1634 spin_lock_irq(&gcwq
->lock
);
1636 if (too_many_workers(pool
)) {
1637 struct worker
*worker
;
1638 unsigned long expires
;
1640 /* idle_list is kept in LIFO order, check the last one */
1641 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
1642 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
1644 if (time_before(jiffies
, expires
))
1645 mod_timer(&pool
->idle_timer
, expires
);
1647 /* it's been idle for too long, wake up manager */
1648 pool
->flags
|= POOL_MANAGE_WORKERS
;
1649 wake_up_worker(pool
);
1653 spin_unlock_irq(&gcwq
->lock
);
1656 static bool send_mayday(struct work_struct
*work
)
1658 struct cpu_workqueue_struct
*cwq
= get_work_cwq(work
);
1659 struct workqueue_struct
*wq
= cwq
->wq
;
1662 if (!(wq
->flags
& WQ_RESCUER
))
1665 /* mayday mayday mayday */
1666 cpu
= cwq
->pool
->gcwq
->cpu
;
1667 /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
1668 if (cpu
== WORK_CPU_UNBOUND
)
1670 if (!mayday_test_and_set_cpu(cpu
, wq
->mayday_mask
))
1671 wake_up_process(wq
->rescuer
->task
);
1675 static void gcwq_mayday_timeout(unsigned long __pool
)
1677 struct worker_pool
*pool
= (void *)__pool
;
1678 struct global_cwq
*gcwq
= pool
->gcwq
;
1679 struct work_struct
*work
;
1681 spin_lock_irq(&gcwq
->lock
);
1683 if (need_to_create_worker(pool
)) {
1685 * We've been trying to create a new worker but
1686 * haven't been successful. We might be hitting an
1687 * allocation deadlock. Send distress signals to
1690 list_for_each_entry(work
, &pool
->worklist
, entry
)
1694 spin_unlock_irq(&gcwq
->lock
);
1696 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INTERVAL
);
1700 * maybe_create_worker - create a new worker if necessary
1701 * @pool: pool to create a new worker for
1703 * Create a new worker for @pool if necessary. @pool is guaranteed to
1704 * have at least one idle worker on return from this function. If
1705 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1706 * sent to all rescuers with works scheduled on @pool to resolve
1707 * possible allocation deadlock.
1709 * On return, need_to_create_worker() is guaranteed to be false and
1710 * may_start_working() true.
1713 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1714 * multiple times. Does GFP_KERNEL allocations. Called only from
1718 * false if no action was taken and gcwq->lock stayed locked, true
1721 static bool maybe_create_worker(struct worker_pool
*pool
)
1722 __releases(&gcwq
->lock
)
1723 __acquires(&gcwq
->lock
)
1725 struct global_cwq
*gcwq
= pool
->gcwq
;
1727 if (!need_to_create_worker(pool
))
1730 spin_unlock_irq(&gcwq
->lock
);
1732 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1733 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INITIAL_TIMEOUT
);
1736 struct worker
*worker
;
1738 worker
= create_worker(pool
);
1740 del_timer_sync(&pool
->mayday_timer
);
1741 spin_lock_irq(&gcwq
->lock
);
1742 start_worker(worker
);
1743 BUG_ON(need_to_create_worker(pool
));
1747 if (!need_to_create_worker(pool
))
1750 __set_current_state(TASK_INTERRUPTIBLE
);
1751 schedule_timeout(CREATE_COOLDOWN
);
1753 if (!need_to_create_worker(pool
))
1757 del_timer_sync(&pool
->mayday_timer
);
1758 spin_lock_irq(&gcwq
->lock
);
1759 if (need_to_create_worker(pool
))
1765 * maybe_destroy_worker - destroy workers which have been idle for a while
1766 * @pool: pool to destroy workers for
1768 * Destroy @pool workers which have been idle for longer than
1769 * IDLE_WORKER_TIMEOUT.
1772 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1773 * multiple times. Called only from manager.
1776 * false if no action was taken and gcwq->lock stayed locked, true
1779 static bool maybe_destroy_workers(struct worker_pool
*pool
)
1783 while (too_many_workers(pool
)) {
1784 struct worker
*worker
;
1785 unsigned long expires
;
1787 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
1788 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
1790 if (time_before(jiffies
, expires
)) {
1791 mod_timer(&pool
->idle_timer
, expires
);
1795 destroy_worker(worker
);
1803 * manage_workers - manage worker pool
1806 * Assume the manager role and manage gcwq worker pool @worker belongs
1807 * to. At any given time, there can be only zero or one manager per
1808 * gcwq. The exclusion is handled automatically by this function.
1810 * The caller can safely start processing works on false return. On
1811 * true return, it's guaranteed that need_to_create_worker() is false
1812 * and may_start_working() is true.
1815 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1816 * multiple times. Does GFP_KERNEL allocations.
1819 * false if no action was taken and gcwq->lock stayed locked, true if
1820 * some action was taken.
1822 static bool manage_workers(struct worker
*worker
)
1824 struct worker_pool
*pool
= worker
->pool
;
1827 if (!mutex_trylock(&pool
->manager_mutex
))
1830 pool
->flags
&= ~POOL_MANAGE_WORKERS
;
1833 * Destroy and then create so that may_start_working() is true
1836 ret
|= maybe_destroy_workers(pool
);
1837 ret
|= maybe_create_worker(pool
);
1839 mutex_unlock(&pool
->manager_mutex
);
1844 * move_linked_works - move linked works to a list
1845 * @work: start of series of works to be scheduled
1846 * @head: target list to append @work to
1847 * @nextp: out paramter for nested worklist walking
1849 * Schedule linked works starting from @work to @head. Work series to
1850 * be scheduled starts at @work and includes any consecutive work with
1851 * WORK_STRUCT_LINKED set in its predecessor.
1853 * If @nextp is not NULL, it's updated to point to the next work of
1854 * the last scheduled work. This allows move_linked_works() to be
1855 * nested inside outer list_for_each_entry_safe().
1858 * spin_lock_irq(gcwq->lock).
1860 static void move_linked_works(struct work_struct
*work
, struct list_head
*head
,
1861 struct work_struct
**nextp
)
1863 struct work_struct
*n
;
1866 * Linked worklist will always end before the end of the list,
1867 * use NULL for list head.
1869 list_for_each_entry_safe_from(work
, n
, NULL
, entry
) {
1870 list_move_tail(&work
->entry
, head
);
1871 if (!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))
1876 * If we're already inside safe list traversal and have moved
1877 * multiple works to the scheduled queue, the next position
1878 * needs to be updated.
1884 static void cwq_activate_first_delayed(struct cpu_workqueue_struct
*cwq
)
1886 struct work_struct
*work
= list_first_entry(&cwq
->delayed_works
,
1887 struct work_struct
, entry
);
1889 trace_workqueue_activate_work(work
);
1890 move_linked_works(work
, &cwq
->pool
->worklist
, NULL
);
1891 __clear_bit(WORK_STRUCT_DELAYED_BIT
, work_data_bits(work
));
1896 * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
1897 * @cwq: cwq of interest
1898 * @color: color of work which left the queue
1899 * @delayed: for a delayed work
1901 * A work either has completed or is removed from pending queue,
1902 * decrement nr_in_flight of its cwq and handle workqueue flushing.
1905 * spin_lock_irq(gcwq->lock).
1907 static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct
*cwq
, int color
,
1910 /* ignore uncolored works */
1911 if (color
== WORK_NO_COLOR
)
1914 cwq
->nr_in_flight
[color
]--;
1918 if (!list_empty(&cwq
->delayed_works
)) {
1919 /* one down, submit a delayed one */
1920 if (cwq
->nr_active
< cwq
->max_active
)
1921 cwq_activate_first_delayed(cwq
);
1925 /* is flush in progress and are we at the flushing tip? */
1926 if (likely(cwq
->flush_color
!= color
))
1929 /* are there still in-flight works? */
1930 if (cwq
->nr_in_flight
[color
])
1933 /* this cwq is done, clear flush_color */
1934 cwq
->flush_color
= -1;
1937 * If this was the last cwq, wake up the first flusher. It
1938 * will handle the rest.
1940 if (atomic_dec_and_test(&cwq
->wq
->nr_cwqs_to_flush
))
1941 complete(&cwq
->wq
->first_flusher
->done
);
1945 * process_one_work - process single work
1947 * @work: work to process
1949 * Process @work. This function contains all the logics necessary to
1950 * process a single work including synchronization against and
1951 * interaction with other workers on the same cpu, queueing and
1952 * flushing. As long as context requirement is met, any worker can
1953 * call this function to process a work.
1956 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1958 static void process_one_work(struct worker
*worker
, struct work_struct
*work
)
1959 __releases(&gcwq
->lock
)
1960 __acquires(&gcwq
->lock
)
1962 struct cpu_workqueue_struct
*cwq
= get_work_cwq(work
);
1963 struct worker_pool
*pool
= worker
->pool
;
1964 struct global_cwq
*gcwq
= pool
->gcwq
;
1965 struct hlist_head
*bwh
= busy_worker_head(gcwq
, work
);
1966 bool cpu_intensive
= cwq
->wq
->flags
& WQ_CPU_INTENSIVE
;
1967 work_func_t f
= work
->func
;
1969 struct worker
*collision
;
1970 #ifdef CONFIG_LOCKDEP
1972 * It is permissible to free the struct work_struct from
1973 * inside the function that is called from it, this we need to
1974 * take into account for lockdep too. To avoid bogus "held
1975 * lock freed" warnings as well as problems when looking into
1976 * work->lockdep_map, make a copy and use that here.
1978 struct lockdep_map lockdep_map
;
1980 lockdep_copy_map(&lockdep_map
, &work
->lockdep_map
);
1983 * Ensure we're on the correct CPU. DISASSOCIATED test is
1984 * necessary to avoid spurious warnings from rescuers servicing the
1985 * unbound or a disassociated gcwq.
1987 WARN_ON_ONCE(!(worker
->flags
& (WORKER_UNBOUND
| WORKER_REBIND
)) &&
1988 !(gcwq
->flags
& GCWQ_DISASSOCIATED
) &&
1989 raw_smp_processor_id() != gcwq
->cpu
);
1992 * A single work shouldn't be executed concurrently by
1993 * multiple workers on a single cpu. Check whether anyone is
1994 * already processing the work. If so, defer the work to the
1995 * currently executing one.
1997 collision
= __find_worker_executing_work(gcwq
, bwh
, work
);
1998 if (unlikely(collision
)) {
1999 move_linked_works(work
, &collision
->scheduled
, NULL
);
2003 /* claim and process */
2004 debug_work_deactivate(work
);
2005 hlist_add_head(&worker
->hentry
, bwh
);
2006 worker
->current_work
= work
;
2007 worker
->current_cwq
= cwq
;
2008 work_color
= get_work_color(work
);
2010 /* record the current cpu number in the work data and dequeue */
2011 set_work_cpu(work
, gcwq
->cpu
);
2012 list_del_init(&work
->entry
);
2015 * CPU intensive works don't participate in concurrency
2016 * management. They're the scheduler's responsibility.
2018 if (unlikely(cpu_intensive
))
2019 worker_set_flags(worker
, WORKER_CPU_INTENSIVE
, true);
2022 * Unbound gcwq isn't concurrency managed and work items should be
2023 * executed ASAP. Wake up another worker if necessary.
2025 if ((worker
->flags
& WORKER_UNBOUND
) && need_more_worker(pool
))
2026 wake_up_worker(pool
);
2028 spin_unlock_irq(&gcwq
->lock
);
2030 work_clear_pending(work
);
2031 lock_map_acquire_read(&cwq
->wq
->lockdep_map
);
2032 lock_map_acquire(&lockdep_map
);
2033 trace_workqueue_execute_start(work
);
2036 * While we must be careful to not use "work" after this, the trace
2037 * point will only record its address.
2039 trace_workqueue_execute_end(work
);
2040 lock_map_release(&lockdep_map
);
2041 lock_map_release(&cwq
->wq
->lockdep_map
);
2043 if (unlikely(in_atomic() || lockdep_depth(current
) > 0)) {
2044 printk(KERN_ERR
"BUG: workqueue leaked lock or atomic: "
2046 current
->comm
, preempt_count(), task_pid_nr(current
));
2047 printk(KERN_ERR
" last function: ");
2048 print_symbol("%s\n", (unsigned long)f
);
2049 debug_show_held_locks(current
);
2053 spin_lock_irq(&gcwq
->lock
);
2055 /* clear cpu intensive status */
2056 if (unlikely(cpu_intensive
))
2057 worker_clr_flags(worker
, WORKER_CPU_INTENSIVE
);
2059 /* we're done with it, release */
2060 hlist_del_init(&worker
->hentry
);
2061 worker
->current_work
= NULL
;
2062 worker
->current_cwq
= NULL
;
2063 cwq_dec_nr_in_flight(cwq
, work_color
, false);
2067 * process_scheduled_works - process scheduled works
2070 * Process all scheduled works. Please note that the scheduled list
2071 * may change while processing a work, so this function repeatedly
2072 * fetches a work from the top and executes it.
2075 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
2078 static void process_scheduled_works(struct worker
*worker
)
2080 while (!list_empty(&worker
->scheduled
)) {
2081 struct work_struct
*work
= list_first_entry(&worker
->scheduled
,
2082 struct work_struct
, entry
);
2083 process_one_work(worker
, work
);
2088 * worker_thread - the worker thread function
2091 * The gcwq worker thread function. There's a single dynamic pool of
2092 * these per each cpu. These workers process all works regardless of
2093 * their specific target workqueue. The only exception is works which
2094 * belong to workqueues with a rescuer which will be explained in
2097 static int worker_thread(void *__worker
)
2099 struct worker
*worker
= __worker
;
2100 struct worker_pool
*pool
= worker
->pool
;
2101 struct global_cwq
*gcwq
= pool
->gcwq
;
2103 /* tell the scheduler that this is a workqueue worker */
2104 worker
->task
->flags
|= PF_WQ_WORKER
;
2106 spin_lock_irq(&gcwq
->lock
);
2109 * DIE can be set only while idle and REBIND set while busy has
2110 * @worker->rebind_work scheduled. Checking here is enough.
2112 if (unlikely(worker
->flags
& (WORKER_REBIND
| WORKER_DIE
))) {
2113 spin_unlock_irq(&gcwq
->lock
);
2115 if (worker
->flags
& WORKER_DIE
) {
2116 worker
->task
->flags
&= ~PF_WQ_WORKER
;
2120 idle_worker_rebind(worker
);
2124 worker_leave_idle(worker
);
2126 /* no more worker necessary? */
2127 if (!need_more_worker(pool
))
2130 /* do we need to manage? */
2131 if (unlikely(!may_start_working(pool
)) && manage_workers(worker
))
2135 * ->scheduled list can only be filled while a worker is
2136 * preparing to process a work or actually processing it.
2137 * Make sure nobody diddled with it while I was sleeping.
2139 BUG_ON(!list_empty(&worker
->scheduled
));
2142 * When control reaches this point, we're guaranteed to have
2143 * at least one idle worker or that someone else has already
2144 * assumed the manager role.
2146 worker_clr_flags(worker
, WORKER_PREP
);
2149 struct work_struct
*work
=
2150 list_first_entry(&pool
->worklist
,
2151 struct work_struct
, entry
);
2153 if (likely(!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))) {
2154 /* optimization path, not strictly necessary */
2155 process_one_work(worker
, work
);
2156 if (unlikely(!list_empty(&worker
->scheduled
)))
2157 process_scheduled_works(worker
);
2159 move_linked_works(work
, &worker
->scheduled
, NULL
);
2160 process_scheduled_works(worker
);
2162 } while (keep_working(pool
));
2164 worker_set_flags(worker
, WORKER_PREP
, false);
2166 if (unlikely(need_to_manage_workers(pool
)) && manage_workers(worker
))
2170 * gcwq->lock is held and there's no work to process and no
2171 * need to manage, sleep. Workers are woken up only while
2172 * holding gcwq->lock or from local cpu, so setting the
2173 * current state before releasing gcwq->lock is enough to
2174 * prevent losing any event.
2176 worker_enter_idle(worker
);
2177 __set_current_state(TASK_INTERRUPTIBLE
);
2178 spin_unlock_irq(&gcwq
->lock
);
2184 * rescuer_thread - the rescuer thread function
2185 * @__wq: the associated workqueue
2187 * Workqueue rescuer thread function. There's one rescuer for each
2188 * workqueue which has WQ_RESCUER set.
2190 * Regular work processing on a gcwq may block trying to create a new
2191 * worker which uses GFP_KERNEL allocation which has slight chance of
2192 * developing into deadlock if some works currently on the same queue
2193 * need to be processed to satisfy the GFP_KERNEL allocation. This is
2194 * the problem rescuer solves.
2196 * When such condition is possible, the gcwq summons rescuers of all
2197 * workqueues which have works queued on the gcwq and let them process
2198 * those works so that forward progress can be guaranteed.
2200 * This should happen rarely.
2202 static int rescuer_thread(void *__wq
)
2204 struct workqueue_struct
*wq
= __wq
;
2205 struct worker
*rescuer
= wq
->rescuer
;
2206 struct list_head
*scheduled
= &rescuer
->scheduled
;
2207 bool is_unbound
= wq
->flags
& WQ_UNBOUND
;
2210 set_user_nice(current
, RESCUER_NICE_LEVEL
);
2212 set_current_state(TASK_INTERRUPTIBLE
);
2214 if (kthread_should_stop())
2218 * See whether any cpu is asking for help. Unbounded
2219 * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND.
2221 for_each_mayday_cpu(cpu
, wq
->mayday_mask
) {
2222 unsigned int tcpu
= is_unbound
? WORK_CPU_UNBOUND
: cpu
;
2223 struct cpu_workqueue_struct
*cwq
= get_cwq(tcpu
, wq
);
2224 struct worker_pool
*pool
= cwq
->pool
;
2225 struct global_cwq
*gcwq
= pool
->gcwq
;
2226 struct work_struct
*work
, *n
;
2228 __set_current_state(TASK_RUNNING
);
2229 mayday_clear_cpu(cpu
, wq
->mayday_mask
);
2231 /* migrate to the target cpu if possible */
2232 rescuer
->pool
= pool
;
2233 worker_maybe_bind_and_lock(rescuer
);
2236 * Slurp in all works issued via this workqueue and
2239 BUG_ON(!list_empty(&rescuer
->scheduled
));
2240 list_for_each_entry_safe(work
, n
, &pool
->worklist
, entry
)
2241 if (get_work_cwq(work
) == cwq
)
2242 move_linked_works(work
, scheduled
, &n
);
2244 process_scheduled_works(rescuer
);
2247 * Leave this gcwq. If keep_working() is %true, notify a
2248 * regular worker; otherwise, we end up with 0 concurrency
2249 * and stalling the execution.
2251 if (keep_working(pool
))
2252 wake_up_worker(pool
);
2254 spin_unlock_irq(&gcwq
->lock
);
2262 struct work_struct work
;
2263 struct completion done
;
2266 static void wq_barrier_func(struct work_struct
*work
)
2268 struct wq_barrier
*barr
= container_of(work
, struct wq_barrier
, work
);
2269 complete(&barr
->done
);
2273 * insert_wq_barrier - insert a barrier work
2274 * @cwq: cwq to insert barrier into
2275 * @barr: wq_barrier to insert
2276 * @target: target work to attach @barr to
2277 * @worker: worker currently executing @target, NULL if @target is not executing
2279 * @barr is linked to @target such that @barr is completed only after
2280 * @target finishes execution. Please note that the ordering
2281 * guarantee is observed only with respect to @target and on the local
2284 * Currently, a queued barrier can't be canceled. This is because
2285 * try_to_grab_pending() can't determine whether the work to be
2286 * grabbed is at the head of the queue and thus can't clear LINKED
2287 * flag of the previous work while there must be a valid next work
2288 * after a work with LINKED flag set.
2290 * Note that when @worker is non-NULL, @target may be modified
2291 * underneath us, so we can't reliably determine cwq from @target.
2294 * spin_lock_irq(gcwq->lock).
2296 static void insert_wq_barrier(struct cpu_workqueue_struct
*cwq
,
2297 struct wq_barrier
*barr
,
2298 struct work_struct
*target
, struct worker
*worker
)
2300 struct list_head
*head
;
2301 unsigned int linked
= 0;
2304 * debugobject calls are safe here even with gcwq->lock locked
2305 * as we know for sure that this will not trigger any of the
2306 * checks and call back into the fixup functions where we
2309 INIT_WORK_ONSTACK(&barr
->work
, wq_barrier_func
);
2310 __set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(&barr
->work
));
2311 init_completion(&barr
->done
);
2314 * If @target is currently being executed, schedule the
2315 * barrier to the worker; otherwise, put it after @target.
2318 head
= worker
->scheduled
.next
;
2320 unsigned long *bits
= work_data_bits(target
);
2322 head
= target
->entry
.next
;
2323 /* there can already be other linked works, inherit and set */
2324 linked
= *bits
& WORK_STRUCT_LINKED
;
2325 __set_bit(WORK_STRUCT_LINKED_BIT
, bits
);
2328 debug_work_activate(&barr
->work
);
2329 insert_work(cwq
, &barr
->work
, head
,
2330 work_color_to_flags(WORK_NO_COLOR
) | linked
);
2334 * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing
2335 * @wq: workqueue being flushed
2336 * @flush_color: new flush color, < 0 for no-op
2337 * @work_color: new work color, < 0 for no-op
2339 * Prepare cwqs for workqueue flushing.
2341 * If @flush_color is non-negative, flush_color on all cwqs should be
2342 * -1. If no cwq has in-flight commands at the specified color, all
2343 * cwq->flush_color's stay at -1 and %false is returned. If any cwq
2344 * has in flight commands, its cwq->flush_color is set to
2345 * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq
2346 * wakeup logic is armed and %true is returned.
2348 * The caller should have initialized @wq->first_flusher prior to
2349 * calling this function with non-negative @flush_color. If
2350 * @flush_color is negative, no flush color update is done and %false
2353 * If @work_color is non-negative, all cwqs should have the same
2354 * work_color which is previous to @work_color and all will be
2355 * advanced to @work_color.
2358 * mutex_lock(wq->flush_mutex).
2361 * %true if @flush_color >= 0 and there's something to flush. %false
2364 static bool flush_workqueue_prep_cwqs(struct workqueue_struct
*wq
,
2365 int flush_color
, int work_color
)
2370 if (flush_color
>= 0) {
2371 BUG_ON(atomic_read(&wq
->nr_cwqs_to_flush
));
2372 atomic_set(&wq
->nr_cwqs_to_flush
, 1);
2375 for_each_cwq_cpu(cpu
, wq
) {
2376 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
2377 struct global_cwq
*gcwq
= cwq
->pool
->gcwq
;
2379 spin_lock_irq(&gcwq
->lock
);
2381 if (flush_color
>= 0) {
2382 BUG_ON(cwq
->flush_color
!= -1);
2384 if (cwq
->nr_in_flight
[flush_color
]) {
2385 cwq
->flush_color
= flush_color
;
2386 atomic_inc(&wq
->nr_cwqs_to_flush
);
2391 if (work_color
>= 0) {
2392 BUG_ON(work_color
!= work_next_color(cwq
->work_color
));
2393 cwq
->work_color
= work_color
;
2396 spin_unlock_irq(&gcwq
->lock
);
2399 if (flush_color
>= 0 && atomic_dec_and_test(&wq
->nr_cwqs_to_flush
))
2400 complete(&wq
->first_flusher
->done
);
2406 * flush_workqueue - ensure that any scheduled work has run to completion.
2407 * @wq: workqueue to flush
2409 * Forces execution of the workqueue and blocks until its completion.
2410 * This is typically used in driver shutdown handlers.
2412 * We sleep until all works which were queued on entry have been handled,
2413 * but we are not livelocked by new incoming ones.
2415 void flush_workqueue(struct workqueue_struct
*wq
)
2417 struct wq_flusher this_flusher
= {
2418 .list
= LIST_HEAD_INIT(this_flusher
.list
),
2420 .done
= COMPLETION_INITIALIZER_ONSTACK(this_flusher
.done
),
2424 lock_map_acquire(&wq
->lockdep_map
);
2425 lock_map_release(&wq
->lockdep_map
);
2427 mutex_lock(&wq
->flush_mutex
);
2430 * Start-to-wait phase
2432 next_color
= work_next_color(wq
->work_color
);
2434 if (next_color
!= wq
->flush_color
) {
2436 * Color space is not full. The current work_color
2437 * becomes our flush_color and work_color is advanced
2440 BUG_ON(!list_empty(&wq
->flusher_overflow
));
2441 this_flusher
.flush_color
= wq
->work_color
;
2442 wq
->work_color
= next_color
;
2444 if (!wq
->first_flusher
) {
2445 /* no flush in progress, become the first flusher */
2446 BUG_ON(wq
->flush_color
!= this_flusher
.flush_color
);
2448 wq
->first_flusher
= &this_flusher
;
2450 if (!flush_workqueue_prep_cwqs(wq
, wq
->flush_color
,
2452 /* nothing to flush, done */
2453 wq
->flush_color
= next_color
;
2454 wq
->first_flusher
= NULL
;
2459 BUG_ON(wq
->flush_color
== this_flusher
.flush_color
);
2460 list_add_tail(&this_flusher
.list
, &wq
->flusher_queue
);
2461 flush_workqueue_prep_cwqs(wq
, -1, wq
->work_color
);
2465 * Oops, color space is full, wait on overflow queue.
2466 * The next flush completion will assign us
2467 * flush_color and transfer to flusher_queue.
2469 list_add_tail(&this_flusher
.list
, &wq
->flusher_overflow
);
2472 mutex_unlock(&wq
->flush_mutex
);
2474 wait_for_completion(&this_flusher
.done
);
2477 * Wake-up-and-cascade phase
2479 * First flushers are responsible for cascading flushes and
2480 * handling overflow. Non-first flushers can simply return.
2482 if (wq
->first_flusher
!= &this_flusher
)
2485 mutex_lock(&wq
->flush_mutex
);
2487 /* we might have raced, check again with mutex held */
2488 if (wq
->first_flusher
!= &this_flusher
)
2491 wq
->first_flusher
= NULL
;
2493 BUG_ON(!list_empty(&this_flusher
.list
));
2494 BUG_ON(wq
->flush_color
!= this_flusher
.flush_color
);
2497 struct wq_flusher
*next
, *tmp
;
2499 /* complete all the flushers sharing the current flush color */
2500 list_for_each_entry_safe(next
, tmp
, &wq
->flusher_queue
, list
) {
2501 if (next
->flush_color
!= wq
->flush_color
)
2503 list_del_init(&next
->list
);
2504 complete(&next
->done
);
2507 BUG_ON(!list_empty(&wq
->flusher_overflow
) &&
2508 wq
->flush_color
!= work_next_color(wq
->work_color
));
2510 /* this flush_color is finished, advance by one */
2511 wq
->flush_color
= work_next_color(wq
->flush_color
);
2513 /* one color has been freed, handle overflow queue */
2514 if (!list_empty(&wq
->flusher_overflow
)) {
2516 * Assign the same color to all overflowed
2517 * flushers, advance work_color and append to
2518 * flusher_queue. This is the start-to-wait
2519 * phase for these overflowed flushers.
2521 list_for_each_entry(tmp
, &wq
->flusher_overflow
, list
)
2522 tmp
->flush_color
= wq
->work_color
;
2524 wq
->work_color
= work_next_color(wq
->work_color
);
2526 list_splice_tail_init(&wq
->flusher_overflow
,
2527 &wq
->flusher_queue
);
2528 flush_workqueue_prep_cwqs(wq
, -1, wq
->work_color
);
2531 if (list_empty(&wq
->flusher_queue
)) {
2532 BUG_ON(wq
->flush_color
!= wq
->work_color
);
2537 * Need to flush more colors. Make the next flusher
2538 * the new first flusher and arm cwqs.
2540 BUG_ON(wq
->flush_color
== wq
->work_color
);
2541 BUG_ON(wq
->flush_color
!= next
->flush_color
);
2543 list_del_init(&next
->list
);
2544 wq
->first_flusher
= next
;
2546 if (flush_workqueue_prep_cwqs(wq
, wq
->flush_color
, -1))
2550 * Meh... this color is already done, clear first
2551 * flusher and repeat cascading.
2553 wq
->first_flusher
= NULL
;
2557 mutex_unlock(&wq
->flush_mutex
);
2559 EXPORT_SYMBOL_GPL(flush_workqueue
);
2562 * drain_workqueue - drain a workqueue
2563 * @wq: workqueue to drain
2565 * Wait until the workqueue becomes empty. While draining is in progress,
2566 * only chain queueing is allowed. IOW, only currently pending or running
2567 * work items on @wq can queue further work items on it. @wq is flushed
2568 * repeatedly until it becomes empty. The number of flushing is detemined
2569 * by the depth of chaining and should be relatively short. Whine if it
2572 void drain_workqueue(struct workqueue_struct
*wq
)
2574 unsigned int flush_cnt
= 0;
2578 * __queue_work() needs to test whether there are drainers, is much
2579 * hotter than drain_workqueue() and already looks at @wq->flags.
2580 * Use WQ_DRAINING so that queue doesn't have to check nr_drainers.
2582 spin_lock(&workqueue_lock
);
2583 if (!wq
->nr_drainers
++)
2584 wq
->flags
|= WQ_DRAINING
;
2585 spin_unlock(&workqueue_lock
);
2587 flush_workqueue(wq
);
2589 for_each_cwq_cpu(cpu
, wq
) {
2590 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
2593 spin_lock_irq(&cwq
->pool
->gcwq
->lock
);
2594 drained
= !cwq
->nr_active
&& list_empty(&cwq
->delayed_works
);
2595 spin_unlock_irq(&cwq
->pool
->gcwq
->lock
);
2600 if (++flush_cnt
== 10 ||
2601 (flush_cnt
% 100 == 0 && flush_cnt
<= 1000))
2602 pr_warning("workqueue %s: flush on destruction isn't complete after %u tries\n",
2603 wq
->name
, flush_cnt
);
2607 spin_lock(&workqueue_lock
);
2608 if (!--wq
->nr_drainers
)
2609 wq
->flags
&= ~WQ_DRAINING
;
2610 spin_unlock(&workqueue_lock
);
2612 EXPORT_SYMBOL_GPL(drain_workqueue
);
2614 static bool start_flush_work(struct work_struct
*work
, struct wq_barrier
*barr
,
2615 bool wait_executing
)
2617 struct worker
*worker
= NULL
;
2618 struct global_cwq
*gcwq
;
2619 struct cpu_workqueue_struct
*cwq
;
2622 gcwq
= get_work_gcwq(work
);
2626 spin_lock_irq(&gcwq
->lock
);
2627 if (!list_empty(&work
->entry
)) {
2629 * See the comment near try_to_grab_pending()->smp_rmb().
2630 * If it was re-queued to a different gcwq under us, we
2631 * are not going to wait.
2634 cwq
= get_work_cwq(work
);
2635 if (unlikely(!cwq
|| gcwq
!= cwq
->pool
->gcwq
))
2637 } else if (wait_executing
) {
2638 worker
= find_worker_executing_work(gcwq
, work
);
2641 cwq
= worker
->current_cwq
;
2645 insert_wq_barrier(cwq
, barr
, work
, worker
);
2646 spin_unlock_irq(&gcwq
->lock
);
2649 * If @max_active is 1 or rescuer is in use, flushing another work
2650 * item on the same workqueue may lead to deadlock. Make sure the
2651 * flusher is not running on the same workqueue by verifying write
2654 if (cwq
->wq
->saved_max_active
== 1 || cwq
->wq
->flags
& WQ_RESCUER
)
2655 lock_map_acquire(&cwq
->wq
->lockdep_map
);
2657 lock_map_acquire_read(&cwq
->wq
->lockdep_map
);
2658 lock_map_release(&cwq
->wq
->lockdep_map
);
2662 spin_unlock_irq(&gcwq
->lock
);
2667 * flush_work - wait for a work to finish executing the last queueing instance
2668 * @work: the work to flush
2670 * Wait until @work has finished execution. This function considers
2671 * only the last queueing instance of @work. If @work has been
2672 * enqueued across different CPUs on a non-reentrant workqueue or on
2673 * multiple workqueues, @work might still be executing on return on
2674 * some of the CPUs from earlier queueing.
2676 * If @work was queued only on a non-reentrant, ordered or unbound
2677 * workqueue, @work is guaranteed to be idle on return if it hasn't
2678 * been requeued since flush started.
2681 * %true if flush_work() waited for the work to finish execution,
2682 * %false if it was already idle.
2684 bool flush_work(struct work_struct
*work
)
2686 struct wq_barrier barr
;
2688 lock_map_acquire(&work
->lockdep_map
);
2689 lock_map_release(&work
->lockdep_map
);
2691 if (start_flush_work(work
, &barr
, true)) {
2692 wait_for_completion(&barr
.done
);
2693 destroy_work_on_stack(&barr
.work
);
2698 EXPORT_SYMBOL_GPL(flush_work
);
2700 static bool wait_on_cpu_work(struct global_cwq
*gcwq
, struct work_struct
*work
)
2702 struct wq_barrier barr
;
2703 struct worker
*worker
;
2705 spin_lock_irq(&gcwq
->lock
);
2707 worker
= find_worker_executing_work(gcwq
, work
);
2708 if (unlikely(worker
))
2709 insert_wq_barrier(worker
->current_cwq
, &barr
, work
, worker
);
2711 spin_unlock_irq(&gcwq
->lock
);
2713 if (unlikely(worker
)) {
2714 wait_for_completion(&barr
.done
);
2715 destroy_work_on_stack(&barr
.work
);
2721 static bool wait_on_work(struct work_struct
*work
)
2728 lock_map_acquire(&work
->lockdep_map
);
2729 lock_map_release(&work
->lockdep_map
);
2731 for_each_gcwq_cpu(cpu
)
2732 ret
|= wait_on_cpu_work(get_gcwq(cpu
), work
);
2737 * flush_work_sync - wait until a work has finished execution
2738 * @work: the work to flush
2740 * Wait until @work has finished execution. On return, it's
2741 * guaranteed that all queueing instances of @work which happened
2742 * before this function is called are finished. In other words, if
2743 * @work hasn't been requeued since this function was called, @work is
2744 * guaranteed to be idle on return.
2747 * %true if flush_work_sync() waited for the work to finish execution,
2748 * %false if it was already idle.
2750 bool flush_work_sync(struct work_struct
*work
)
2752 struct wq_barrier barr
;
2753 bool pending
, waited
;
2755 /* we'll wait for executions separately, queue barr only if pending */
2756 pending
= start_flush_work(work
, &barr
, false);
2758 /* wait for executions to finish */
2759 waited
= wait_on_work(work
);
2761 /* wait for the pending one */
2763 wait_for_completion(&barr
.done
);
2764 destroy_work_on_stack(&barr
.work
);
2767 return pending
|| waited
;
2769 EXPORT_SYMBOL_GPL(flush_work_sync
);
2772 * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
2773 * so this work can't be re-armed in any way.
2775 static int try_to_grab_pending(struct work_struct
*work
)
2777 struct global_cwq
*gcwq
;
2780 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
)))
2784 * The queueing is in progress, or it is already queued. Try to
2785 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
2787 gcwq
= get_work_gcwq(work
);
2791 spin_lock_irq(&gcwq
->lock
);
2792 if (!list_empty(&work
->entry
)) {
2794 * This work is queued, but perhaps we locked the wrong gcwq.
2795 * In that case we must see the new value after rmb(), see
2796 * insert_work()->wmb().
2799 if (gcwq
== get_work_gcwq(work
)) {
2800 debug_work_deactivate(work
);
2801 list_del_init(&work
->entry
);
2802 cwq_dec_nr_in_flight(get_work_cwq(work
),
2803 get_work_color(work
),
2804 *work_data_bits(work
) & WORK_STRUCT_DELAYED
);
2808 spin_unlock_irq(&gcwq
->lock
);
2813 static bool __cancel_work_timer(struct work_struct
*work
,
2814 struct timer_list
* timer
)
2819 ret
= (timer
&& likely(del_timer(timer
)));
2821 ret
= try_to_grab_pending(work
);
2823 } while (unlikely(ret
< 0));
2825 clear_work_data(work
);
2830 * cancel_work_sync - cancel a work and wait for it to finish
2831 * @work: the work to cancel
2833 * Cancel @work and wait for its execution to finish. This function
2834 * can be used even if the work re-queues itself or migrates to
2835 * another workqueue. On return from this function, @work is
2836 * guaranteed to be not pending or executing on any CPU.
2838 * cancel_work_sync(&delayed_work->work) must not be used for
2839 * delayed_work's. Use cancel_delayed_work_sync() instead.
2841 * The caller must ensure that the workqueue on which @work was last
2842 * queued can't be destroyed before this function returns.
2845 * %true if @work was pending, %false otherwise.
2847 bool cancel_work_sync(struct work_struct
*work
)
2849 return __cancel_work_timer(work
, NULL
);
2851 EXPORT_SYMBOL_GPL(cancel_work_sync
);
2854 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2855 * @dwork: the delayed work to flush
2857 * Delayed timer is cancelled and the pending work is queued for
2858 * immediate execution. Like flush_work(), this function only
2859 * considers the last queueing instance of @dwork.
2862 * %true if flush_work() waited for the work to finish execution,
2863 * %false if it was already idle.
2865 bool flush_delayed_work(struct delayed_work
*dwork
)
2867 if (del_timer_sync(&dwork
->timer
))
2868 __queue_work(raw_smp_processor_id(),
2869 get_work_cwq(&dwork
->work
)->wq
, &dwork
->work
);
2870 return flush_work(&dwork
->work
);
2872 EXPORT_SYMBOL(flush_delayed_work
);
2875 * flush_delayed_work_sync - wait for a dwork to finish
2876 * @dwork: the delayed work to flush
2878 * Delayed timer is cancelled and the pending work is queued for
2879 * execution immediately. Other than timer handling, its behavior
2880 * is identical to flush_work_sync().
2883 * %true if flush_work_sync() waited for the work to finish execution,
2884 * %false if it was already idle.
2886 bool flush_delayed_work_sync(struct delayed_work
*dwork
)
2888 if (del_timer_sync(&dwork
->timer
))
2889 __queue_work(raw_smp_processor_id(),
2890 get_work_cwq(&dwork
->work
)->wq
, &dwork
->work
);
2891 return flush_work_sync(&dwork
->work
);
2893 EXPORT_SYMBOL(flush_delayed_work_sync
);
2896 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
2897 * @dwork: the delayed work cancel
2899 * This is cancel_work_sync() for delayed works.
2902 * %true if @dwork was pending, %false otherwise.
2904 bool cancel_delayed_work_sync(struct delayed_work
*dwork
)
2906 return __cancel_work_timer(&dwork
->work
, &dwork
->timer
);
2908 EXPORT_SYMBOL(cancel_delayed_work_sync
);
2911 * schedule_work - put work task in global workqueue
2912 * @work: job to be done
2914 * Returns zero if @work was already on the kernel-global workqueue and
2915 * non-zero otherwise.
2917 * This puts a job in the kernel-global workqueue if it was not already
2918 * queued and leaves it in the same position on the kernel-global
2919 * workqueue otherwise.
2921 int schedule_work(struct work_struct
*work
)
2923 return queue_work(system_wq
, work
);
2925 EXPORT_SYMBOL(schedule_work
);
2928 * schedule_work_on - put work task on a specific cpu
2929 * @cpu: cpu to put the work task on
2930 * @work: job to be done
2932 * This puts a job on a specific cpu
2934 int schedule_work_on(int cpu
, struct work_struct
*work
)
2936 return queue_work_on(cpu
, system_wq
, work
);
2938 EXPORT_SYMBOL(schedule_work_on
);
2941 * schedule_delayed_work - put work task in global workqueue after delay
2942 * @dwork: job to be done
2943 * @delay: number of jiffies to wait or 0 for immediate execution
2945 * After waiting for a given time this puts a job in the kernel-global
2948 int schedule_delayed_work(struct delayed_work
*dwork
,
2949 unsigned long delay
)
2951 return queue_delayed_work(system_wq
, dwork
, delay
);
2953 EXPORT_SYMBOL(schedule_delayed_work
);
2956 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
2958 * @dwork: job to be done
2959 * @delay: number of jiffies to wait
2961 * After waiting for a given time this puts a job in the kernel-global
2962 * workqueue on the specified CPU.
2964 int schedule_delayed_work_on(int cpu
,
2965 struct delayed_work
*dwork
, unsigned long delay
)
2967 return queue_delayed_work_on(cpu
, system_wq
, dwork
, delay
);
2969 EXPORT_SYMBOL(schedule_delayed_work_on
);
2972 * schedule_on_each_cpu - execute a function synchronously on each online CPU
2973 * @func: the function to call
2975 * schedule_on_each_cpu() executes @func on each online CPU using the
2976 * system workqueue and blocks until all CPUs have completed.
2977 * schedule_on_each_cpu() is very slow.
2980 * 0 on success, -errno on failure.
2982 int schedule_on_each_cpu(work_func_t func
)
2985 struct work_struct __percpu
*works
;
2987 works
= alloc_percpu(struct work_struct
);
2993 for_each_online_cpu(cpu
) {
2994 struct work_struct
*work
= per_cpu_ptr(works
, cpu
);
2996 INIT_WORK(work
, func
);
2997 schedule_work_on(cpu
, work
);
3000 for_each_online_cpu(cpu
)
3001 flush_work(per_cpu_ptr(works
, cpu
));
3009 * flush_scheduled_work - ensure that any scheduled work has run to completion.
3011 * Forces execution of the kernel-global workqueue and blocks until its
3014 * Think twice before calling this function! It's very easy to get into
3015 * trouble if you don't take great care. Either of the following situations
3016 * will lead to deadlock:
3018 * One of the work items currently on the workqueue needs to acquire
3019 * a lock held by your code or its caller.
3021 * Your code is running in the context of a work routine.
3023 * They will be detected by lockdep when they occur, but the first might not
3024 * occur very often. It depends on what work items are on the workqueue and
3025 * what locks they need, which you have no control over.
3027 * In most situations flushing the entire workqueue is overkill; you merely
3028 * need to know that a particular work item isn't queued and isn't running.
3029 * In such cases you should use cancel_delayed_work_sync() or
3030 * cancel_work_sync() instead.
3032 void flush_scheduled_work(void)
3034 flush_workqueue(system_wq
);
3036 EXPORT_SYMBOL(flush_scheduled_work
);
3039 * execute_in_process_context - reliably execute the routine with user context
3040 * @fn: the function to execute
3041 * @ew: guaranteed storage for the execute work structure (must
3042 * be available when the work executes)
3044 * Executes the function immediately if process context is available,
3045 * otherwise schedules the function for delayed execution.
3047 * Returns: 0 - function was executed
3048 * 1 - function was scheduled for execution
3050 int execute_in_process_context(work_func_t fn
, struct execute_work
*ew
)
3052 if (!in_interrupt()) {
3057 INIT_WORK(&ew
->work
, fn
);
3058 schedule_work(&ew
->work
);
3062 EXPORT_SYMBOL_GPL(execute_in_process_context
);
3064 int keventd_up(void)
3066 return system_wq
!= NULL
;
3069 static int alloc_cwqs(struct workqueue_struct
*wq
)
3072 * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
3073 * Make sure that the alignment isn't lower than that of
3074 * unsigned long long.
3076 const size_t size
= sizeof(struct cpu_workqueue_struct
);
3077 const size_t align
= max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS
,
3078 __alignof__(unsigned long long));
3080 if (!(wq
->flags
& WQ_UNBOUND
))
3081 wq
->cpu_wq
.pcpu
= __alloc_percpu(size
, align
);
3086 * Allocate enough room to align cwq and put an extra
3087 * pointer at the end pointing back to the originally
3088 * allocated pointer which will be used for free.
3090 ptr
= kzalloc(size
+ align
+ sizeof(void *), GFP_KERNEL
);
3092 wq
->cpu_wq
.single
= PTR_ALIGN(ptr
, align
);
3093 *(void **)(wq
->cpu_wq
.single
+ 1) = ptr
;
3097 /* just in case, make sure it's actually aligned */
3098 BUG_ON(!IS_ALIGNED(wq
->cpu_wq
.v
, align
));
3099 return wq
->cpu_wq
.v
? 0 : -ENOMEM
;
3102 static void free_cwqs(struct workqueue_struct
*wq
)
3104 if (!(wq
->flags
& WQ_UNBOUND
))
3105 free_percpu(wq
->cpu_wq
.pcpu
);
3106 else if (wq
->cpu_wq
.single
) {
3107 /* the pointer to free is stored right after the cwq */
3108 kfree(*(void **)(wq
->cpu_wq
.single
+ 1));
3112 static int wq_clamp_max_active(int max_active
, unsigned int flags
,
3115 int lim
= flags
& WQ_UNBOUND
? WQ_UNBOUND_MAX_ACTIVE
: WQ_MAX_ACTIVE
;
3117 if (max_active
< 1 || max_active
> lim
)
3118 printk(KERN_WARNING
"workqueue: max_active %d requested for %s "
3119 "is out of range, clamping between %d and %d\n",
3120 max_active
, name
, 1, lim
);
3122 return clamp_val(max_active
, 1, lim
);
3125 struct workqueue_struct
*__alloc_workqueue_key(const char *fmt
,
3128 struct lock_class_key
*key
,
3129 const char *lock_name
, ...)
3131 va_list args
, args1
;
3132 struct workqueue_struct
*wq
;
3136 /* determine namelen, allocate wq and format name */
3137 va_start(args
, lock_name
);
3138 va_copy(args1
, args
);
3139 namelen
= vsnprintf(NULL
, 0, fmt
, args
) + 1;
3141 wq
= kzalloc(sizeof(*wq
) + namelen
, GFP_KERNEL
);
3145 vsnprintf(wq
->name
, namelen
, fmt
, args1
);
3150 * Workqueues which may be used during memory reclaim should
3151 * have a rescuer to guarantee forward progress.
3153 if (flags
& WQ_MEM_RECLAIM
)
3154 flags
|= WQ_RESCUER
;
3156 max_active
= max_active
?: WQ_DFL_ACTIVE
;
3157 max_active
= wq_clamp_max_active(max_active
, flags
, wq
->name
);
3161 wq
->saved_max_active
= max_active
;
3162 mutex_init(&wq
->flush_mutex
);
3163 atomic_set(&wq
->nr_cwqs_to_flush
, 0);
3164 INIT_LIST_HEAD(&wq
->flusher_queue
);
3165 INIT_LIST_HEAD(&wq
->flusher_overflow
);
3167 lockdep_init_map(&wq
->lockdep_map
, lock_name
, key
, 0);
3168 INIT_LIST_HEAD(&wq
->list
);
3170 if (alloc_cwqs(wq
) < 0)
3173 for_each_cwq_cpu(cpu
, wq
) {
3174 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3175 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3176 int pool_idx
= (bool)(flags
& WQ_HIGHPRI
);
3178 BUG_ON((unsigned long)cwq
& WORK_STRUCT_FLAG_MASK
);
3179 cwq
->pool
= &gcwq
->pools
[pool_idx
];
3181 cwq
->flush_color
= -1;
3182 cwq
->max_active
= max_active
;
3183 INIT_LIST_HEAD(&cwq
->delayed_works
);
3186 if (flags
& WQ_RESCUER
) {
3187 struct worker
*rescuer
;
3189 if (!alloc_mayday_mask(&wq
->mayday_mask
, GFP_KERNEL
))
3192 wq
->rescuer
= rescuer
= alloc_worker();
3196 rescuer
->task
= kthread_create(rescuer_thread
, wq
, "%s",
3198 if (IS_ERR(rescuer
->task
))
3201 rescuer
->task
->flags
|= PF_THREAD_BOUND
;
3202 wake_up_process(rescuer
->task
);
3206 * workqueue_lock protects global freeze state and workqueues
3207 * list. Grab it, set max_active accordingly and add the new
3208 * workqueue to workqueues list.
3210 spin_lock(&workqueue_lock
);
3212 if (workqueue_freezing
&& wq
->flags
& WQ_FREEZABLE
)
3213 for_each_cwq_cpu(cpu
, wq
)
3214 get_cwq(cpu
, wq
)->max_active
= 0;
3216 list_add(&wq
->list
, &workqueues
);
3218 spin_unlock(&workqueue_lock
);
3224 free_mayday_mask(wq
->mayday_mask
);
3230 EXPORT_SYMBOL_GPL(__alloc_workqueue_key
);
3233 * destroy_workqueue - safely terminate a workqueue
3234 * @wq: target workqueue
3236 * Safely destroy a workqueue. All work currently pending will be done first.
3238 void destroy_workqueue(struct workqueue_struct
*wq
)
3242 /* drain it before proceeding with destruction */
3243 drain_workqueue(wq
);
3246 * wq list is used to freeze wq, remove from list after
3247 * flushing is complete in case freeze races us.
3249 spin_lock(&workqueue_lock
);
3250 list_del(&wq
->list
);
3251 spin_unlock(&workqueue_lock
);
3254 for_each_cwq_cpu(cpu
, wq
) {
3255 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3258 for (i
= 0; i
< WORK_NR_COLORS
; i
++)
3259 BUG_ON(cwq
->nr_in_flight
[i
]);
3260 BUG_ON(cwq
->nr_active
);
3261 BUG_ON(!list_empty(&cwq
->delayed_works
));
3264 if (wq
->flags
& WQ_RESCUER
) {
3265 kthread_stop(wq
->rescuer
->task
);
3266 free_mayday_mask(wq
->mayday_mask
);
3273 EXPORT_SYMBOL_GPL(destroy_workqueue
);
3276 * workqueue_set_max_active - adjust max_active of a workqueue
3277 * @wq: target workqueue
3278 * @max_active: new max_active value.
3280 * Set max_active of @wq to @max_active.
3283 * Don't call from IRQ context.
3285 void workqueue_set_max_active(struct workqueue_struct
*wq
, int max_active
)
3289 max_active
= wq_clamp_max_active(max_active
, wq
->flags
, wq
->name
);
3291 spin_lock(&workqueue_lock
);
3293 wq
->saved_max_active
= max_active
;
3295 for_each_cwq_cpu(cpu
, wq
) {
3296 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3298 spin_lock_irq(&gcwq
->lock
);
3300 if (!(wq
->flags
& WQ_FREEZABLE
) ||
3301 !(gcwq
->flags
& GCWQ_FREEZING
))
3302 get_cwq(gcwq
->cpu
, wq
)->max_active
= max_active
;
3304 spin_unlock_irq(&gcwq
->lock
);
3307 spin_unlock(&workqueue_lock
);
3309 EXPORT_SYMBOL_GPL(workqueue_set_max_active
);
3312 * workqueue_congested - test whether a workqueue is congested
3313 * @cpu: CPU in question
3314 * @wq: target workqueue
3316 * Test whether @wq's cpu workqueue for @cpu is congested. There is
3317 * no synchronization around this function and the test result is
3318 * unreliable and only useful as advisory hints or for debugging.
3321 * %true if congested, %false otherwise.
3323 bool workqueue_congested(unsigned int cpu
, struct workqueue_struct
*wq
)
3325 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3327 return !list_empty(&cwq
->delayed_works
);
3329 EXPORT_SYMBOL_GPL(workqueue_congested
);
3332 * work_cpu - return the last known associated cpu for @work
3333 * @work: the work of interest
3336 * CPU number if @work was ever queued. WORK_CPU_NONE otherwise.
3338 unsigned int work_cpu(struct work_struct
*work
)
3340 struct global_cwq
*gcwq
= get_work_gcwq(work
);
3342 return gcwq
? gcwq
->cpu
: WORK_CPU_NONE
;
3344 EXPORT_SYMBOL_GPL(work_cpu
);
3347 * work_busy - test whether a work is currently pending or running
3348 * @work: the work to be tested
3350 * Test whether @work is currently pending or running. There is no
3351 * synchronization around this function and the test result is
3352 * unreliable and only useful as advisory hints or for debugging.
3353 * Especially for reentrant wqs, the pending state might hide the
3357 * OR'd bitmask of WORK_BUSY_* bits.
3359 unsigned int work_busy(struct work_struct
*work
)
3361 struct global_cwq
*gcwq
= get_work_gcwq(work
);
3362 unsigned long flags
;
3363 unsigned int ret
= 0;
3368 spin_lock_irqsave(&gcwq
->lock
, flags
);
3370 if (work_pending(work
))
3371 ret
|= WORK_BUSY_PENDING
;
3372 if (find_worker_executing_work(gcwq
, work
))
3373 ret
|= WORK_BUSY_RUNNING
;
3375 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
3379 EXPORT_SYMBOL_GPL(work_busy
);
3384 * There are two challenges in supporting CPU hotplug. Firstly, there
3385 * are a lot of assumptions on strong associations among work, cwq and
3386 * gcwq which make migrating pending and scheduled works very
3387 * difficult to implement without impacting hot paths. Secondly,
3388 * gcwqs serve mix of short, long and very long running works making
3389 * blocked draining impractical.
3391 * This is solved by allowing a gcwq to be disassociated from the CPU
3392 * running as an unbound one and allowing it to be reattached later if the
3393 * cpu comes back online.
3396 /* claim manager positions of all pools */
3397 static void gcwq_claim_management_and_lock(struct global_cwq
*gcwq
)
3399 struct worker_pool
*pool
;
3401 for_each_worker_pool(pool
, gcwq
)
3402 mutex_lock_nested(&pool
->manager_mutex
, pool
- gcwq
->pools
);
3403 spin_lock_irq(&gcwq
->lock
);
3406 /* release manager positions */
3407 static void gcwq_release_management_and_unlock(struct global_cwq
*gcwq
)
3409 struct worker_pool
*pool
;
3411 spin_unlock_irq(&gcwq
->lock
);
3412 for_each_worker_pool(pool
, gcwq
)
3413 mutex_unlock(&pool
->manager_mutex
);
3416 static void gcwq_unbind_fn(struct work_struct
*work
)
3418 struct global_cwq
*gcwq
= get_gcwq(smp_processor_id());
3419 struct worker_pool
*pool
;
3420 struct worker
*worker
;
3421 struct hlist_node
*pos
;
3424 BUG_ON(gcwq
->cpu
!= smp_processor_id());
3426 gcwq_claim_management_and_lock(gcwq
);
3429 * We've claimed all manager positions. Make all workers unbound
3430 * and set DISASSOCIATED. Before this, all workers except for the
3431 * ones which are still executing works from before the last CPU
3432 * down must be on the cpu. After this, they may become diasporas.
3434 for_each_worker_pool(pool
, gcwq
)
3435 list_for_each_entry(worker
, &pool
->idle_list
, entry
)
3436 worker
->flags
|= WORKER_UNBOUND
;
3438 for_each_busy_worker(worker
, i
, pos
, gcwq
)
3439 worker
->flags
|= WORKER_UNBOUND
;
3441 gcwq
->flags
|= GCWQ_DISASSOCIATED
;
3443 gcwq_release_management_and_unlock(gcwq
);
3446 * Call schedule() so that we cross rq->lock and thus can guarantee
3447 * sched callbacks see the %WORKER_UNBOUND flag. This is necessary
3448 * as scheduler callbacks may be invoked from other cpus.
3453 * Sched callbacks are disabled now. Zap nr_running. After this,
3454 * nr_running stays zero and need_more_worker() and keep_working()
3455 * are always true as long as the worklist is not empty. @gcwq now
3456 * behaves as unbound (in terms of concurrency management) gcwq
3457 * which is served by workers tied to the CPU.
3459 * On return from this function, the current worker would trigger
3460 * unbound chain execution of pending work items if other workers
3463 for_each_worker_pool(pool
, gcwq
)
3464 atomic_set(get_pool_nr_running(pool
), 0);
3468 * Workqueues should be brought up before normal priority CPU notifiers.
3469 * This will be registered high priority CPU notifier.
3471 static int __devinit
workqueue_cpu_up_callback(struct notifier_block
*nfb
,
3472 unsigned long action
,
3475 unsigned int cpu
= (unsigned long)hcpu
;
3476 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3477 struct worker_pool
*pool
;
3479 switch (action
& ~CPU_TASKS_FROZEN
) {
3480 case CPU_UP_PREPARE
:
3481 for_each_worker_pool(pool
, gcwq
) {
3482 struct worker
*worker
;
3484 if (pool
->nr_workers
)
3487 worker
= create_worker(pool
);
3491 spin_lock_irq(&gcwq
->lock
);
3492 start_worker(worker
);
3493 spin_unlock_irq(&gcwq
->lock
);
3497 case CPU_DOWN_FAILED
:
3499 gcwq_claim_management_and_lock(gcwq
);
3500 gcwq
->flags
&= ~GCWQ_DISASSOCIATED
;
3501 rebind_workers(gcwq
);
3502 gcwq_release_management_and_unlock(gcwq
);
3509 * Workqueues should be brought down after normal priority CPU notifiers.
3510 * This will be registered as low priority CPU notifier.
3512 static int __devinit
workqueue_cpu_down_callback(struct notifier_block
*nfb
,
3513 unsigned long action
,
3516 unsigned int cpu
= (unsigned long)hcpu
;
3517 struct work_struct unbind_work
;
3519 switch (action
& ~CPU_TASKS_FROZEN
) {
3520 case CPU_DOWN_PREPARE
:
3521 /* unbinding should happen on the local CPU */
3522 INIT_WORK_ONSTACK(&unbind_work
, gcwq_unbind_fn
);
3523 schedule_work_on(cpu
, &unbind_work
);
3524 flush_work(&unbind_work
);
3532 struct work_for_cpu
{
3533 struct completion completion
;
3539 static int do_work_for_cpu(void *_wfc
)
3541 struct work_for_cpu
*wfc
= _wfc
;
3542 wfc
->ret
= wfc
->fn(wfc
->arg
);
3543 complete(&wfc
->completion
);
3548 * work_on_cpu - run a function in user context on a particular cpu
3549 * @cpu: the cpu to run on
3550 * @fn: the function to run
3551 * @arg: the function arg
3553 * This will return the value @fn returns.
3554 * It is up to the caller to ensure that the cpu doesn't go offline.
3555 * The caller must not hold any locks which would prevent @fn from completing.
3557 long work_on_cpu(unsigned int cpu
, long (*fn
)(void *), void *arg
)
3559 struct task_struct
*sub_thread
;
3560 struct work_for_cpu wfc
= {
3561 .completion
= COMPLETION_INITIALIZER_ONSTACK(wfc
.completion
),
3566 sub_thread
= kthread_create(do_work_for_cpu
, &wfc
, "work_for_cpu");
3567 if (IS_ERR(sub_thread
))
3568 return PTR_ERR(sub_thread
);
3569 kthread_bind(sub_thread
, cpu
);
3570 wake_up_process(sub_thread
);
3571 wait_for_completion(&wfc
.completion
);
3574 EXPORT_SYMBOL_GPL(work_on_cpu
);
3575 #endif /* CONFIG_SMP */
3577 #ifdef CONFIG_FREEZER
3580 * freeze_workqueues_begin - begin freezing workqueues
3582 * Start freezing workqueues. After this function returns, all freezable
3583 * workqueues will queue new works to their frozen_works list instead of
3587 * Grabs and releases workqueue_lock and gcwq->lock's.
3589 void freeze_workqueues_begin(void)
3593 spin_lock(&workqueue_lock
);
3595 BUG_ON(workqueue_freezing
);
3596 workqueue_freezing
= true;
3598 for_each_gcwq_cpu(cpu
) {
3599 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3600 struct workqueue_struct
*wq
;
3602 spin_lock_irq(&gcwq
->lock
);
3604 BUG_ON(gcwq
->flags
& GCWQ_FREEZING
);
3605 gcwq
->flags
|= GCWQ_FREEZING
;
3607 list_for_each_entry(wq
, &workqueues
, list
) {
3608 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3610 if (cwq
&& wq
->flags
& WQ_FREEZABLE
)
3611 cwq
->max_active
= 0;
3614 spin_unlock_irq(&gcwq
->lock
);
3617 spin_unlock(&workqueue_lock
);
3621 * freeze_workqueues_busy - are freezable workqueues still busy?
3623 * Check whether freezing is complete. This function must be called
3624 * between freeze_workqueues_begin() and thaw_workqueues().
3627 * Grabs and releases workqueue_lock.
3630 * %true if some freezable workqueues are still busy. %false if freezing
3633 bool freeze_workqueues_busy(void)
3638 spin_lock(&workqueue_lock
);
3640 BUG_ON(!workqueue_freezing
);
3642 for_each_gcwq_cpu(cpu
) {
3643 struct workqueue_struct
*wq
;
3645 * nr_active is monotonically decreasing. It's safe
3646 * to peek without lock.
3648 list_for_each_entry(wq
, &workqueues
, list
) {
3649 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3651 if (!cwq
|| !(wq
->flags
& WQ_FREEZABLE
))
3654 BUG_ON(cwq
->nr_active
< 0);
3655 if (cwq
->nr_active
) {
3662 spin_unlock(&workqueue_lock
);
3667 * thaw_workqueues - thaw workqueues
3669 * Thaw workqueues. Normal queueing is restored and all collected
3670 * frozen works are transferred to their respective gcwq worklists.
3673 * Grabs and releases workqueue_lock and gcwq->lock's.
3675 void thaw_workqueues(void)
3679 spin_lock(&workqueue_lock
);
3681 if (!workqueue_freezing
)
3684 for_each_gcwq_cpu(cpu
) {
3685 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3686 struct worker_pool
*pool
;
3687 struct workqueue_struct
*wq
;
3689 spin_lock_irq(&gcwq
->lock
);
3691 BUG_ON(!(gcwq
->flags
& GCWQ_FREEZING
));
3692 gcwq
->flags
&= ~GCWQ_FREEZING
;
3694 list_for_each_entry(wq
, &workqueues
, list
) {
3695 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3697 if (!cwq
|| !(wq
->flags
& WQ_FREEZABLE
))
3700 /* restore max_active and repopulate worklist */
3701 cwq
->max_active
= wq
->saved_max_active
;
3703 while (!list_empty(&cwq
->delayed_works
) &&
3704 cwq
->nr_active
< cwq
->max_active
)
3705 cwq_activate_first_delayed(cwq
);
3708 for_each_worker_pool(pool
, gcwq
)
3709 wake_up_worker(pool
);
3711 spin_unlock_irq(&gcwq
->lock
);
3714 workqueue_freezing
= false;
3716 spin_unlock(&workqueue_lock
);
3718 #endif /* CONFIG_FREEZER */
3720 static int __init
init_workqueues(void)
3725 cpu_notifier(workqueue_cpu_up_callback
, CPU_PRI_WORKQUEUE_UP
);
3726 cpu_notifier(workqueue_cpu_down_callback
, CPU_PRI_WORKQUEUE_DOWN
);
3728 /* initialize gcwqs */
3729 for_each_gcwq_cpu(cpu
) {
3730 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3731 struct worker_pool
*pool
;
3733 spin_lock_init(&gcwq
->lock
);
3735 gcwq
->flags
|= GCWQ_DISASSOCIATED
;
3737 for (i
= 0; i
< BUSY_WORKER_HASH_SIZE
; i
++)
3738 INIT_HLIST_HEAD(&gcwq
->busy_hash
[i
]);
3740 for_each_worker_pool(pool
, gcwq
) {
3742 INIT_LIST_HEAD(&pool
->worklist
);
3743 INIT_LIST_HEAD(&pool
->idle_list
);
3745 init_timer_deferrable(&pool
->idle_timer
);
3746 pool
->idle_timer
.function
= idle_worker_timeout
;
3747 pool
->idle_timer
.data
= (unsigned long)pool
;
3749 setup_timer(&pool
->mayday_timer
, gcwq_mayday_timeout
,
3750 (unsigned long)pool
);
3752 mutex_init(&pool
->manager_mutex
);
3753 ida_init(&pool
->worker_ida
);
3756 init_waitqueue_head(&gcwq
->rebind_hold
);
3759 /* create the initial worker */
3760 for_each_online_gcwq_cpu(cpu
) {
3761 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3762 struct worker_pool
*pool
;
3764 if (cpu
!= WORK_CPU_UNBOUND
)
3765 gcwq
->flags
&= ~GCWQ_DISASSOCIATED
;
3767 for_each_worker_pool(pool
, gcwq
) {
3768 struct worker
*worker
;
3770 worker
= create_worker(pool
);
3772 spin_lock_irq(&gcwq
->lock
);
3773 start_worker(worker
);
3774 spin_unlock_irq(&gcwq
->lock
);
3778 system_wq
= alloc_workqueue("events", 0, 0);
3779 system_long_wq
= alloc_workqueue("events_long", 0, 0);
3780 system_nrt_wq
= alloc_workqueue("events_nrt", WQ_NON_REENTRANT
, 0);
3781 system_unbound_wq
= alloc_workqueue("events_unbound", WQ_UNBOUND
,
3782 WQ_UNBOUND_MAX_ACTIVE
);
3783 system_freezable_wq
= alloc_workqueue("events_freezable",
3785 system_nrt_freezable_wq
= alloc_workqueue("events_nrt_freezable",
3786 WQ_NON_REENTRANT
| WQ_FREEZABLE
, 0);
3787 BUG_ON(!system_wq
|| !system_long_wq
|| !system_nrt_wq
||
3788 !system_unbound_wq
|| !system_freezable_wq
||
3789 !system_nrt_freezable_wq
);
3792 early_initcall(init_workqueues
);