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 * assoc_mutex 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 */
69 POOL_MANAGING_WORKERS
= 1 << 1, /* managing workers */
72 WORKER_STARTED
= 1 << 0, /* started */
73 WORKER_DIE
= 1 << 1, /* die die die */
74 WORKER_IDLE
= 1 << 2, /* is idle */
75 WORKER_PREP
= 1 << 3, /* preparing to run works */
76 WORKER_CPU_INTENSIVE
= 1 << 6, /* cpu intensive */
77 WORKER_UNBOUND
= 1 << 7, /* worker is unbound */
79 WORKER_NOT_RUNNING
= WORKER_PREP
| 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.
130 * The poor guys doing the actual heavy lifting. All on-duty workers
131 * are either serving the manager role, on idle list or on busy hash.
134 /* on idle list while idle, on busy hash table while busy */
136 struct list_head entry
; /* L: while idle */
137 struct hlist_node hentry
; /* L: while busy */
140 struct work_struct
*current_work
; /* L: work being processed */
141 struct cpu_workqueue_struct
*current_cwq
; /* L: current_work's cwq */
142 struct list_head scheduled
; /* L: scheduled works */
143 struct task_struct
*task
; /* I: worker task */
144 struct worker_pool
*pool
; /* I: the associated pool */
145 /* 64 bytes boundary on 64bit, 32 on 32bit */
146 unsigned long last_active
; /* L: last active timestamp */
147 unsigned int flags
; /* X: flags */
148 int id
; /* I: worker id */
150 /* for rebinding worker to CPU */
151 struct work_struct rebind_work
; /* L: for busy worker */
155 struct global_cwq
*gcwq
; /* I: the owning gcwq */
156 unsigned int flags
; /* X: flags */
158 struct list_head worklist
; /* L: list of pending works */
159 int nr_workers
; /* L: total number of workers */
161 /* nr_idle includes the ones off idle_list for rebinding */
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 assoc_mutex
; /* protect GCWQ_DISASSOCIATED */
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
[NR_WORKER_POOLS
];
187 /* normal and highpri pools */
188 } ____cacheline_aligned_in_smp
;
191 * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of
192 * work_struct->data are used for flags and thus cwqs need to be
193 * aligned at two's power of the number of flag bits.
195 struct cpu_workqueue_struct
{
196 struct worker_pool
*pool
; /* I: the associated pool */
197 struct workqueue_struct
*wq
; /* I: the owning workqueue */
198 int work_color
; /* L: current color */
199 int flush_color
; /* L: flushing color */
200 int nr_in_flight
[WORK_NR_COLORS
];
201 /* L: nr of in_flight works */
202 int nr_active
; /* L: nr of active works */
203 int max_active
; /* L: max active works */
204 struct list_head delayed_works
; /* L: delayed works */
208 * Structure used to wait for workqueue flush.
211 struct list_head list
; /* F: list of flushers */
212 int flush_color
; /* F: flush color waiting for */
213 struct completion done
; /* flush completion */
217 * All cpumasks are assumed to be always set on UP and thus can't be
218 * used to determine whether there's something to be done.
221 typedef cpumask_var_t mayday_mask_t
;
222 #define mayday_test_and_set_cpu(cpu, mask) \
223 cpumask_test_and_set_cpu((cpu), (mask))
224 #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask))
225 #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask))
226 #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp))
227 #define free_mayday_mask(mask) free_cpumask_var((mask))
229 typedef unsigned long mayday_mask_t
;
230 #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask))
231 #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask))
232 #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask))
233 #define alloc_mayday_mask(maskp, gfp) true
234 #define free_mayday_mask(mask) do { } while (0)
238 * The externally visible workqueue abstraction is an array of
239 * per-CPU workqueues:
241 struct workqueue_struct
{
242 unsigned int flags
; /* W: WQ_* flags */
244 struct cpu_workqueue_struct __percpu
*pcpu
;
245 struct cpu_workqueue_struct
*single
;
247 } cpu_wq
; /* I: cwq's */
248 struct list_head list
; /* W: list of all workqueues */
250 struct mutex flush_mutex
; /* protects wq flushing */
251 int work_color
; /* F: current work color */
252 int flush_color
; /* F: current flush color */
253 atomic_t nr_cwqs_to_flush
; /* flush in progress */
254 struct wq_flusher
*first_flusher
; /* F: first flusher */
255 struct list_head flusher_queue
; /* F: flush waiters */
256 struct list_head flusher_overflow
; /* F: flush overflow list */
258 mayday_mask_t mayday_mask
; /* cpus requesting rescue */
259 struct worker
*rescuer
; /* I: rescue worker */
261 int nr_drainers
; /* W: drain in progress */
262 int saved_max_active
; /* W: saved cwq max_active */
263 #ifdef CONFIG_LOCKDEP
264 struct lockdep_map lockdep_map
;
266 char name
[]; /* I: workqueue name */
269 struct workqueue_struct
*system_wq __read_mostly
;
270 EXPORT_SYMBOL_GPL(system_wq
);
271 struct workqueue_struct
*system_highpri_wq __read_mostly
;
272 EXPORT_SYMBOL_GPL(system_highpri_wq
);
273 struct workqueue_struct
*system_long_wq __read_mostly
;
274 EXPORT_SYMBOL_GPL(system_long_wq
);
275 struct workqueue_struct
*system_unbound_wq __read_mostly
;
276 EXPORT_SYMBOL_GPL(system_unbound_wq
);
277 struct workqueue_struct
*system_freezable_wq __read_mostly
;
278 EXPORT_SYMBOL_GPL(system_freezable_wq
);
280 #define CREATE_TRACE_POINTS
281 #include <trace/events/workqueue.h>
283 #define for_each_worker_pool(pool, gcwq) \
284 for ((pool) = &(gcwq)->pools[0]; \
285 (pool) < &(gcwq)->pools[NR_WORKER_POOLS]; (pool)++)
287 #define for_each_busy_worker(worker, i, pos, gcwq) \
288 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \
289 hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
291 static inline int __next_gcwq_cpu(int cpu
, const struct cpumask
*mask
,
294 if (cpu
< nr_cpu_ids
) {
296 cpu
= cpumask_next(cpu
, mask
);
297 if (cpu
< nr_cpu_ids
)
301 return WORK_CPU_UNBOUND
;
303 return WORK_CPU_NONE
;
306 static inline int __next_wq_cpu(int cpu
, const struct cpumask
*mask
,
307 struct workqueue_struct
*wq
)
309 return __next_gcwq_cpu(cpu
, mask
, !(wq
->flags
& WQ_UNBOUND
) ? 1 : 2);
315 * An extra gcwq is defined for an invalid cpu number
316 * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any
317 * specific CPU. The following iterators are similar to
318 * for_each_*_cpu() iterators but also considers the unbound gcwq.
320 * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND
321 * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND
322 * for_each_cwq_cpu() : possible CPUs for bound workqueues,
323 * WORK_CPU_UNBOUND for unbound workqueues
325 #define for_each_gcwq_cpu(cpu) \
326 for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \
327 (cpu) < WORK_CPU_NONE; \
328 (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3))
330 #define for_each_online_gcwq_cpu(cpu) \
331 for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \
332 (cpu) < WORK_CPU_NONE; \
333 (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3))
335 #define for_each_cwq_cpu(cpu, wq) \
336 for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \
337 (cpu) < WORK_CPU_NONE; \
338 (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq)))
340 #ifdef CONFIG_DEBUG_OBJECTS_WORK
342 static struct debug_obj_descr work_debug_descr
;
344 static void *work_debug_hint(void *addr
)
346 return ((struct work_struct
*) addr
)->func
;
350 * fixup_init is called when:
351 * - an active object is initialized
353 static int work_fixup_init(void *addr
, enum debug_obj_state state
)
355 struct work_struct
*work
= addr
;
358 case ODEBUG_STATE_ACTIVE
:
359 cancel_work_sync(work
);
360 debug_object_init(work
, &work_debug_descr
);
368 * fixup_activate is called when:
369 * - an active object is activated
370 * - an unknown object is activated (might be a statically initialized object)
372 static int work_fixup_activate(void *addr
, enum debug_obj_state state
)
374 struct work_struct
*work
= addr
;
378 case ODEBUG_STATE_NOTAVAILABLE
:
380 * This is not really a fixup. The work struct was
381 * statically initialized. We just make sure that it
382 * is tracked in the object tracker.
384 if (test_bit(WORK_STRUCT_STATIC_BIT
, work_data_bits(work
))) {
385 debug_object_init(work
, &work_debug_descr
);
386 debug_object_activate(work
, &work_debug_descr
);
392 case ODEBUG_STATE_ACTIVE
:
401 * fixup_free is called when:
402 * - an active object is freed
404 static int work_fixup_free(void *addr
, enum debug_obj_state state
)
406 struct work_struct
*work
= addr
;
409 case ODEBUG_STATE_ACTIVE
:
410 cancel_work_sync(work
);
411 debug_object_free(work
, &work_debug_descr
);
418 static struct debug_obj_descr work_debug_descr
= {
419 .name
= "work_struct",
420 .debug_hint
= work_debug_hint
,
421 .fixup_init
= work_fixup_init
,
422 .fixup_activate
= work_fixup_activate
,
423 .fixup_free
= work_fixup_free
,
426 static inline void debug_work_activate(struct work_struct
*work
)
428 debug_object_activate(work
, &work_debug_descr
);
431 static inline void debug_work_deactivate(struct work_struct
*work
)
433 debug_object_deactivate(work
, &work_debug_descr
);
436 void __init_work(struct work_struct
*work
, int onstack
)
439 debug_object_init_on_stack(work
, &work_debug_descr
);
441 debug_object_init(work
, &work_debug_descr
);
443 EXPORT_SYMBOL_GPL(__init_work
);
445 void destroy_work_on_stack(struct work_struct
*work
)
447 debug_object_free(work
, &work_debug_descr
);
449 EXPORT_SYMBOL_GPL(destroy_work_on_stack
);
452 static inline void debug_work_activate(struct work_struct
*work
) { }
453 static inline void debug_work_deactivate(struct work_struct
*work
) { }
456 /* Serializes the accesses to the list of workqueues. */
457 static DEFINE_SPINLOCK(workqueue_lock
);
458 static LIST_HEAD(workqueues
);
459 static bool workqueue_freezing
; /* W: have wqs started freezing? */
462 * The almighty global cpu workqueues. nr_running is the only field
463 * which is expected to be used frequently by other cpus via
464 * try_to_wake_up(). Put it in a separate cacheline.
466 static DEFINE_PER_CPU(struct global_cwq
, global_cwq
);
467 static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t
, pool_nr_running
[NR_WORKER_POOLS
]);
470 * Global cpu workqueue and nr_running counter for unbound gcwq. The
471 * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its
472 * workers have WORKER_UNBOUND set.
474 static struct global_cwq unbound_global_cwq
;
475 static atomic_t unbound_pool_nr_running
[NR_WORKER_POOLS
] = {
476 [0 ... NR_WORKER_POOLS
- 1] = ATOMIC_INIT(0), /* always 0 */
479 static int worker_thread(void *__worker
);
481 static int worker_pool_pri(struct worker_pool
*pool
)
483 return pool
- pool
->gcwq
->pools
;
486 static struct global_cwq
*get_gcwq(unsigned int cpu
)
488 if (cpu
!= WORK_CPU_UNBOUND
)
489 return &per_cpu(global_cwq
, cpu
);
491 return &unbound_global_cwq
;
494 static atomic_t
*get_pool_nr_running(struct worker_pool
*pool
)
496 int cpu
= pool
->gcwq
->cpu
;
497 int idx
= worker_pool_pri(pool
);
499 if (cpu
!= WORK_CPU_UNBOUND
)
500 return &per_cpu(pool_nr_running
, cpu
)[idx
];
502 return &unbound_pool_nr_running
[idx
];
505 static struct cpu_workqueue_struct
*get_cwq(unsigned int cpu
,
506 struct workqueue_struct
*wq
)
508 if (!(wq
->flags
& WQ_UNBOUND
)) {
509 if (likely(cpu
< nr_cpu_ids
))
510 return per_cpu_ptr(wq
->cpu_wq
.pcpu
, cpu
);
511 } else if (likely(cpu
== WORK_CPU_UNBOUND
))
512 return wq
->cpu_wq
.single
;
516 static unsigned int work_color_to_flags(int color
)
518 return color
<< WORK_STRUCT_COLOR_SHIFT
;
521 static int get_work_color(struct work_struct
*work
)
523 return (*work_data_bits(work
) >> WORK_STRUCT_COLOR_SHIFT
) &
524 ((1 << WORK_STRUCT_COLOR_BITS
) - 1);
527 static int work_next_color(int color
)
529 return (color
+ 1) % WORK_NR_COLORS
;
533 * While queued, %WORK_STRUCT_CWQ is set and non flag bits of a work's data
534 * contain the pointer to the queued cwq. Once execution starts, the flag
535 * is cleared and the high bits contain OFFQ flags and CPU number.
537 * set_work_cwq(), set_work_cpu_and_clear_pending(), mark_work_canceling()
538 * and clear_work_data() can be used to set the cwq, cpu or clear
539 * work->data. These functions should only be called while the work is
540 * owned - ie. while the PENDING bit is set.
542 * get_work_[g]cwq() can be used to obtain the gcwq or cwq corresponding to
543 * a work. gcwq is available once the work has been queued anywhere after
544 * initialization until it is sync canceled. cwq is available only while
545 * the work item is queued.
547 * %WORK_OFFQ_CANCELING is used to mark a work item which is being
548 * canceled. While being canceled, a work item may have its PENDING set
549 * but stay off timer and worklist for arbitrarily long and nobody should
550 * try to steal the PENDING bit.
552 static inline void set_work_data(struct work_struct
*work
, unsigned long data
,
555 BUG_ON(!work_pending(work
));
556 atomic_long_set(&work
->data
, data
| flags
| work_static(work
));
559 static void set_work_cwq(struct work_struct
*work
,
560 struct cpu_workqueue_struct
*cwq
,
561 unsigned long extra_flags
)
563 set_work_data(work
, (unsigned long)cwq
,
564 WORK_STRUCT_PENDING
| WORK_STRUCT_CWQ
| extra_flags
);
567 static void set_work_cpu_and_clear_pending(struct work_struct
*work
,
571 * The following wmb is paired with the implied mb in
572 * test_and_set_bit(PENDING) and ensures all updates to @work made
573 * here are visible to and precede any updates by the next PENDING
577 set_work_data(work
, (unsigned long)cpu
<< WORK_OFFQ_CPU_SHIFT
, 0);
580 static void clear_work_data(struct work_struct
*work
)
582 smp_wmb(); /* see set_work_cpu_and_clear_pending() */
583 set_work_data(work
, WORK_STRUCT_NO_CPU
, 0);
586 static struct cpu_workqueue_struct
*get_work_cwq(struct work_struct
*work
)
588 unsigned long data
= atomic_long_read(&work
->data
);
590 if (data
& WORK_STRUCT_CWQ
)
591 return (void *)(data
& WORK_STRUCT_WQ_DATA_MASK
);
596 static struct global_cwq
*get_work_gcwq(struct work_struct
*work
)
598 unsigned long data
= atomic_long_read(&work
->data
);
601 if (data
& WORK_STRUCT_CWQ
)
602 return ((struct cpu_workqueue_struct
*)
603 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
->gcwq
;
605 cpu
= data
>> WORK_OFFQ_CPU_SHIFT
;
606 if (cpu
== WORK_CPU_NONE
)
609 BUG_ON(cpu
>= nr_cpu_ids
&& cpu
!= WORK_CPU_UNBOUND
);
610 return get_gcwq(cpu
);
613 static void mark_work_canceling(struct work_struct
*work
)
615 struct global_cwq
*gcwq
= get_work_gcwq(work
);
616 unsigned long cpu
= gcwq
? gcwq
->cpu
: WORK_CPU_NONE
;
618 set_work_data(work
, (cpu
<< WORK_OFFQ_CPU_SHIFT
) | WORK_OFFQ_CANCELING
,
619 WORK_STRUCT_PENDING
);
622 static bool work_is_canceling(struct work_struct
*work
)
624 unsigned long data
= atomic_long_read(&work
->data
);
626 return !(data
& WORK_STRUCT_CWQ
) && (data
& WORK_OFFQ_CANCELING
);
630 * Policy functions. These define the policies on how the global worker
631 * pools are managed. Unless noted otherwise, these functions assume that
632 * they're being called with gcwq->lock held.
635 static bool __need_more_worker(struct worker_pool
*pool
)
637 return !atomic_read(get_pool_nr_running(pool
));
641 * Need to wake up a worker? Called from anything but currently
644 * Note that, because unbound workers never contribute to nr_running, this
645 * function will always return %true for unbound gcwq as long as the
646 * worklist isn't empty.
648 static bool need_more_worker(struct worker_pool
*pool
)
650 return !list_empty(&pool
->worklist
) && __need_more_worker(pool
);
653 /* Can I start working? Called from busy but !running workers. */
654 static bool may_start_working(struct worker_pool
*pool
)
656 return pool
->nr_idle
;
659 /* Do I need to keep working? Called from currently running workers. */
660 static bool keep_working(struct worker_pool
*pool
)
662 atomic_t
*nr_running
= get_pool_nr_running(pool
);
664 return !list_empty(&pool
->worklist
) && atomic_read(nr_running
) <= 1;
667 /* Do we need a new worker? Called from manager. */
668 static bool need_to_create_worker(struct worker_pool
*pool
)
670 return need_more_worker(pool
) && !may_start_working(pool
);
673 /* Do I need to be the manager? */
674 static bool need_to_manage_workers(struct worker_pool
*pool
)
676 return need_to_create_worker(pool
) ||
677 (pool
->flags
& POOL_MANAGE_WORKERS
);
680 /* Do we have too many workers and should some go away? */
681 static bool too_many_workers(struct worker_pool
*pool
)
683 bool managing
= pool
->flags
& POOL_MANAGING_WORKERS
;
684 int nr_idle
= pool
->nr_idle
+ managing
; /* manager is considered idle */
685 int nr_busy
= pool
->nr_workers
- nr_idle
;
688 * nr_idle and idle_list may disagree if idle rebinding is in
689 * progress. Never return %true if idle_list is empty.
691 if (list_empty(&pool
->idle_list
))
694 return nr_idle
> 2 && (nr_idle
- 2) * MAX_IDLE_WORKERS_RATIO
>= nr_busy
;
701 /* Return the first worker. Safe with preemption disabled */
702 static struct worker
*first_worker(struct worker_pool
*pool
)
704 if (unlikely(list_empty(&pool
->idle_list
)))
707 return list_first_entry(&pool
->idle_list
, struct worker
, entry
);
711 * wake_up_worker - wake up an idle worker
712 * @pool: worker pool to wake worker from
714 * Wake up the first idle worker of @pool.
717 * spin_lock_irq(gcwq->lock).
719 static void wake_up_worker(struct worker_pool
*pool
)
721 struct worker
*worker
= first_worker(pool
);
724 wake_up_process(worker
->task
);
728 * wq_worker_waking_up - a worker is waking up
729 * @task: task waking up
730 * @cpu: CPU @task is waking up to
732 * This function is called during try_to_wake_up() when a worker is
736 * spin_lock_irq(rq->lock)
738 void wq_worker_waking_up(struct task_struct
*task
, unsigned int cpu
)
740 struct worker
*worker
= kthread_data(task
);
742 if (!(worker
->flags
& WORKER_NOT_RUNNING
))
743 atomic_inc(get_pool_nr_running(worker
->pool
));
747 * wq_worker_sleeping - a worker is going to sleep
748 * @task: task going to sleep
749 * @cpu: CPU in question, must be the current CPU number
751 * This function is called during schedule() when a busy worker is
752 * going to sleep. Worker on the same cpu can be woken up by
753 * returning pointer to its task.
756 * spin_lock_irq(rq->lock)
759 * Worker task on @cpu to wake up, %NULL if none.
761 struct task_struct
*wq_worker_sleeping(struct task_struct
*task
,
764 struct worker
*worker
= kthread_data(task
), *to_wakeup
= NULL
;
765 struct worker_pool
*pool
= worker
->pool
;
766 atomic_t
*nr_running
= get_pool_nr_running(pool
);
768 if (worker
->flags
& WORKER_NOT_RUNNING
)
771 /* this can only happen on the local cpu */
772 BUG_ON(cpu
!= raw_smp_processor_id());
775 * The counterpart of the following dec_and_test, implied mb,
776 * worklist not empty test sequence is in insert_work().
777 * Please read comment there.
779 * NOT_RUNNING is clear. This means that we're bound to and
780 * running on the local cpu w/ rq lock held and preemption
781 * disabled, which in turn means that none else could be
782 * manipulating idle_list, so dereferencing idle_list without gcwq
785 if (atomic_dec_and_test(nr_running
) && !list_empty(&pool
->worklist
))
786 to_wakeup
= first_worker(pool
);
787 return to_wakeup
? to_wakeup
->task
: NULL
;
791 * worker_set_flags - set worker flags and adjust nr_running accordingly
793 * @flags: flags to set
794 * @wakeup: wakeup an idle worker if necessary
796 * Set @flags in @worker->flags and adjust nr_running accordingly. If
797 * nr_running becomes zero and @wakeup is %true, an idle worker is
801 * spin_lock_irq(gcwq->lock)
803 static inline void worker_set_flags(struct worker
*worker
, unsigned int flags
,
806 struct worker_pool
*pool
= worker
->pool
;
808 WARN_ON_ONCE(worker
->task
!= current
);
811 * If transitioning into NOT_RUNNING, adjust nr_running and
812 * wake up an idle worker as necessary if requested by
815 if ((flags
& WORKER_NOT_RUNNING
) &&
816 !(worker
->flags
& WORKER_NOT_RUNNING
)) {
817 atomic_t
*nr_running
= get_pool_nr_running(pool
);
820 if (atomic_dec_and_test(nr_running
) &&
821 !list_empty(&pool
->worklist
))
822 wake_up_worker(pool
);
824 atomic_dec(nr_running
);
827 worker
->flags
|= flags
;
831 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
833 * @flags: flags to clear
835 * Clear @flags in @worker->flags and adjust nr_running accordingly.
838 * spin_lock_irq(gcwq->lock)
840 static inline void worker_clr_flags(struct worker
*worker
, unsigned int flags
)
842 struct worker_pool
*pool
= worker
->pool
;
843 unsigned int oflags
= worker
->flags
;
845 WARN_ON_ONCE(worker
->task
!= current
);
847 worker
->flags
&= ~flags
;
850 * If transitioning out of NOT_RUNNING, increment nr_running. Note
851 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
852 * of multiple flags, not a single flag.
854 if ((flags
& WORKER_NOT_RUNNING
) && (oflags
& WORKER_NOT_RUNNING
))
855 if (!(worker
->flags
& WORKER_NOT_RUNNING
))
856 atomic_inc(get_pool_nr_running(pool
));
860 * busy_worker_head - return the busy hash head for a work
861 * @gcwq: gcwq of interest
862 * @work: work to be hashed
864 * Return hash head of @gcwq for @work.
867 * spin_lock_irq(gcwq->lock).
870 * Pointer to the hash head.
872 static struct hlist_head
*busy_worker_head(struct global_cwq
*gcwq
,
873 struct work_struct
*work
)
875 const int base_shift
= ilog2(sizeof(struct work_struct
));
876 unsigned long v
= (unsigned long)work
;
878 /* simple shift and fold hash, do we need something better? */
880 v
+= v
>> BUSY_WORKER_HASH_ORDER
;
881 v
&= BUSY_WORKER_HASH_MASK
;
883 return &gcwq
->busy_hash
[v
];
887 * __find_worker_executing_work - find worker which is executing a work
888 * @gcwq: gcwq of interest
889 * @bwh: hash head as returned by busy_worker_head()
890 * @work: work to find worker for
892 * Find a worker which is executing @work on @gcwq. @bwh should be
893 * the hash head obtained by calling busy_worker_head() with the same
897 * spin_lock_irq(gcwq->lock).
900 * Pointer to worker which is executing @work if found, NULL
903 static struct worker
*__find_worker_executing_work(struct global_cwq
*gcwq
,
904 struct hlist_head
*bwh
,
905 struct work_struct
*work
)
907 struct worker
*worker
;
908 struct hlist_node
*tmp
;
910 hlist_for_each_entry(worker
, tmp
, bwh
, hentry
)
911 if (worker
->current_work
== work
)
917 * find_worker_executing_work - find worker which is executing a work
918 * @gcwq: gcwq of interest
919 * @work: work to find worker for
921 * Find a worker which is executing @work on @gcwq. This function is
922 * identical to __find_worker_executing_work() except that this
923 * function calculates @bwh itself.
926 * spin_lock_irq(gcwq->lock).
929 * Pointer to worker which is executing @work if found, NULL
932 static struct worker
*find_worker_executing_work(struct global_cwq
*gcwq
,
933 struct work_struct
*work
)
935 return __find_worker_executing_work(gcwq
, busy_worker_head(gcwq
, work
),
940 * move_linked_works - move linked works to a list
941 * @work: start of series of works to be scheduled
942 * @head: target list to append @work to
943 * @nextp: out paramter for nested worklist walking
945 * Schedule linked works starting from @work to @head. Work series to
946 * be scheduled starts at @work and includes any consecutive work with
947 * WORK_STRUCT_LINKED set in its predecessor.
949 * If @nextp is not NULL, it's updated to point to the next work of
950 * the last scheduled work. This allows move_linked_works() to be
951 * nested inside outer list_for_each_entry_safe().
954 * spin_lock_irq(gcwq->lock).
956 static void move_linked_works(struct work_struct
*work
, struct list_head
*head
,
957 struct work_struct
**nextp
)
959 struct work_struct
*n
;
962 * Linked worklist will always end before the end of the list,
963 * use NULL for list head.
965 list_for_each_entry_safe_from(work
, n
, NULL
, entry
) {
966 list_move_tail(&work
->entry
, head
);
967 if (!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))
972 * If we're already inside safe list traversal and have moved
973 * multiple works to the scheduled queue, the next position
974 * needs to be updated.
980 static void cwq_activate_first_delayed(struct cpu_workqueue_struct
*cwq
)
982 struct work_struct
*work
= list_first_entry(&cwq
->delayed_works
,
983 struct work_struct
, entry
);
985 trace_workqueue_activate_work(work
);
986 move_linked_works(work
, &cwq
->pool
->worklist
, NULL
);
987 __clear_bit(WORK_STRUCT_DELAYED_BIT
, work_data_bits(work
));
992 * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
993 * @cwq: cwq of interest
994 * @color: color of work which left the queue
995 * @delayed: for a delayed work
997 * A work either has completed or is removed from pending queue,
998 * decrement nr_in_flight of its cwq and handle workqueue flushing.
1001 * spin_lock_irq(gcwq->lock).
1003 static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct
*cwq
, int color
,
1006 /* ignore uncolored works */
1007 if (color
== WORK_NO_COLOR
)
1010 cwq
->nr_in_flight
[color
]--;
1014 if (!list_empty(&cwq
->delayed_works
)) {
1015 /* one down, submit a delayed one */
1016 if (cwq
->nr_active
< cwq
->max_active
)
1017 cwq_activate_first_delayed(cwq
);
1021 /* is flush in progress and are we at the flushing tip? */
1022 if (likely(cwq
->flush_color
!= color
))
1025 /* are there still in-flight works? */
1026 if (cwq
->nr_in_flight
[color
])
1029 /* this cwq is done, clear flush_color */
1030 cwq
->flush_color
= -1;
1033 * If this was the last cwq, wake up the first flusher. It
1034 * will handle the rest.
1036 if (atomic_dec_and_test(&cwq
->wq
->nr_cwqs_to_flush
))
1037 complete(&cwq
->wq
->first_flusher
->done
);
1041 * try_to_grab_pending - steal work item from worklist and disable irq
1042 * @work: work item to steal
1043 * @is_dwork: @work is a delayed_work
1044 * @flags: place to store irq state
1046 * Try to grab PENDING bit of @work. This function can handle @work in any
1047 * stable state - idle, on timer or on worklist. Return values are
1049 * 1 if @work was pending and we successfully stole PENDING
1050 * 0 if @work was idle and we claimed PENDING
1051 * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
1052 * -ENOENT if someone else is canceling @work, this state may persist
1053 * for arbitrarily long
1055 * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
1056 * interrupted while holding PENDING and @work off queue, irq must be
1057 * disabled on entry. This, combined with delayed_work->timer being
1058 * irqsafe, ensures that we return -EAGAIN for finite short period of time.
1060 * On successful return, >= 0, irq is disabled and the caller is
1061 * responsible for releasing it using local_irq_restore(*@flags).
1063 * This function is safe to call from any context including IRQ handler.
1065 static int try_to_grab_pending(struct work_struct
*work
, bool is_dwork
,
1066 unsigned long *flags
)
1068 struct global_cwq
*gcwq
;
1070 WARN_ON_ONCE(in_irq());
1072 local_irq_save(*flags
);
1074 /* try to steal the timer if it exists */
1076 struct delayed_work
*dwork
= to_delayed_work(work
);
1079 * dwork->timer is irqsafe. If del_timer() fails, it's
1080 * guaranteed that the timer is not queued anywhere and not
1081 * running on the local CPU.
1083 if (likely(del_timer(&dwork
->timer
)))
1087 /* try to claim PENDING the normal way */
1088 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
)))
1092 * The queueing is in progress, or it is already queued. Try to
1093 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
1095 gcwq
= get_work_gcwq(work
);
1099 spin_lock(&gcwq
->lock
);
1100 if (!list_empty(&work
->entry
)) {
1102 * This work is queued, but perhaps we locked the wrong gcwq.
1103 * In that case we must see the new value after rmb(), see
1104 * insert_work()->wmb().
1107 if (gcwq
== get_work_gcwq(work
)) {
1108 debug_work_deactivate(work
);
1109 list_del_init(&work
->entry
);
1110 cwq_dec_nr_in_flight(get_work_cwq(work
),
1111 get_work_color(work
),
1112 *work_data_bits(work
) & WORK_STRUCT_DELAYED
);
1114 spin_unlock(&gcwq
->lock
);
1118 spin_unlock(&gcwq
->lock
);
1120 local_irq_restore(*flags
);
1121 if (work_is_canceling(work
))
1128 * insert_work - insert a work into gcwq
1129 * @cwq: cwq @work belongs to
1130 * @work: work to insert
1131 * @head: insertion point
1132 * @extra_flags: extra WORK_STRUCT_* flags to set
1134 * Insert @work which belongs to @cwq into @gcwq after @head.
1135 * @extra_flags is or'd to work_struct flags.
1138 * spin_lock_irq(gcwq->lock).
1140 static void insert_work(struct cpu_workqueue_struct
*cwq
,
1141 struct work_struct
*work
, struct list_head
*head
,
1142 unsigned int extra_flags
)
1144 struct worker_pool
*pool
= cwq
->pool
;
1146 /* we own @work, set data and link */
1147 set_work_cwq(work
, cwq
, extra_flags
);
1150 * Ensure that we get the right work->data if we see the
1151 * result of list_add() below, see try_to_grab_pending().
1155 list_add_tail(&work
->entry
, head
);
1158 * Ensure either worker_sched_deactivated() sees the above
1159 * list_add_tail() or we see zero nr_running to avoid workers
1160 * lying around lazily while there are works to be processed.
1164 if (__need_more_worker(pool
))
1165 wake_up_worker(pool
);
1169 * Test whether @work is being queued from another work executing on the
1170 * same workqueue. This is rather expensive and should only be used from
1173 static bool is_chained_work(struct workqueue_struct
*wq
)
1175 unsigned long flags
;
1178 for_each_gcwq_cpu(cpu
) {
1179 struct global_cwq
*gcwq
= get_gcwq(cpu
);
1180 struct worker
*worker
;
1181 struct hlist_node
*pos
;
1184 spin_lock_irqsave(&gcwq
->lock
, flags
);
1185 for_each_busy_worker(worker
, i
, pos
, gcwq
) {
1186 if (worker
->task
!= current
)
1188 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
1190 * I'm @worker, no locking necessary. See if @work
1191 * is headed to the same workqueue.
1193 return worker
->current_cwq
->wq
== wq
;
1195 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
1200 static void __queue_work(unsigned int cpu
, struct workqueue_struct
*wq
,
1201 struct work_struct
*work
)
1203 struct global_cwq
*gcwq
;
1204 struct cpu_workqueue_struct
*cwq
;
1205 struct list_head
*worklist
;
1206 unsigned int work_flags
;
1207 unsigned int req_cpu
= cpu
;
1210 * While a work item is PENDING && off queue, a task trying to
1211 * steal the PENDING will busy-loop waiting for it to either get
1212 * queued or lose PENDING. Grabbing PENDING and queueing should
1213 * happen with IRQ disabled.
1215 WARN_ON_ONCE(!irqs_disabled());
1217 debug_work_activate(work
);
1219 /* if dying, only works from the same workqueue are allowed */
1220 if (unlikely(wq
->flags
& WQ_DRAINING
) &&
1221 WARN_ON_ONCE(!is_chained_work(wq
)))
1224 /* determine gcwq to use */
1225 if (!(wq
->flags
& WQ_UNBOUND
)) {
1226 struct global_cwq
*last_gcwq
;
1228 if (cpu
== WORK_CPU_UNBOUND
)
1229 cpu
= raw_smp_processor_id();
1232 * It's multi cpu. If @work was previously on a different
1233 * cpu, it might still be running there, in which case the
1234 * work needs to be queued on that cpu to guarantee
1237 gcwq
= get_gcwq(cpu
);
1238 last_gcwq
= get_work_gcwq(work
);
1240 if (last_gcwq
&& last_gcwq
!= gcwq
) {
1241 struct worker
*worker
;
1243 spin_lock(&last_gcwq
->lock
);
1245 worker
= find_worker_executing_work(last_gcwq
, work
);
1247 if (worker
&& worker
->current_cwq
->wq
== wq
)
1250 /* meh... not running there, queue here */
1251 spin_unlock(&last_gcwq
->lock
);
1252 spin_lock(&gcwq
->lock
);
1255 spin_lock(&gcwq
->lock
);
1258 gcwq
= get_gcwq(WORK_CPU_UNBOUND
);
1259 spin_lock(&gcwq
->lock
);
1262 /* gcwq determined, get cwq and queue */
1263 cwq
= get_cwq(gcwq
->cpu
, wq
);
1264 trace_workqueue_queue_work(req_cpu
, cwq
, work
);
1266 if (WARN_ON(!list_empty(&work
->entry
))) {
1267 spin_unlock(&gcwq
->lock
);
1271 cwq
->nr_in_flight
[cwq
->work_color
]++;
1272 work_flags
= work_color_to_flags(cwq
->work_color
);
1274 if (likely(cwq
->nr_active
< cwq
->max_active
)) {
1275 trace_workqueue_activate_work(work
);
1277 worklist
= &cwq
->pool
->worklist
;
1279 work_flags
|= WORK_STRUCT_DELAYED
;
1280 worklist
= &cwq
->delayed_works
;
1283 insert_work(cwq
, work
, worklist
, work_flags
);
1285 spin_unlock(&gcwq
->lock
);
1289 * queue_work_on - queue work on specific cpu
1290 * @cpu: CPU number to execute work on
1291 * @wq: workqueue to use
1292 * @work: work to queue
1294 * Returns %false if @work was already on a queue, %true otherwise.
1296 * We queue the work to a specific CPU, the caller must ensure it
1299 bool queue_work_on(int cpu
, struct workqueue_struct
*wq
,
1300 struct work_struct
*work
)
1303 unsigned long flags
;
1305 local_irq_save(flags
);
1307 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1308 __queue_work(cpu
, wq
, work
);
1312 local_irq_restore(flags
);
1315 EXPORT_SYMBOL_GPL(queue_work_on
);
1318 * queue_work - queue work on a workqueue
1319 * @wq: workqueue to use
1320 * @work: work to queue
1322 * Returns %false if @work was already on a queue, %true otherwise.
1324 * We queue the work to the CPU on which it was submitted, but if the CPU dies
1325 * it can be processed by another CPU.
1327 bool queue_work(struct workqueue_struct
*wq
, struct work_struct
*work
)
1329 return queue_work_on(WORK_CPU_UNBOUND
, wq
, work
);
1331 EXPORT_SYMBOL_GPL(queue_work
);
1333 void delayed_work_timer_fn(unsigned long __data
)
1335 struct delayed_work
*dwork
= (struct delayed_work
*)__data
;
1336 struct cpu_workqueue_struct
*cwq
= get_work_cwq(&dwork
->work
);
1338 /* should have been called from irqsafe timer with irq already off */
1339 __queue_work(dwork
->cpu
, cwq
->wq
, &dwork
->work
);
1341 EXPORT_SYMBOL_GPL(delayed_work_timer_fn
);
1343 static void __queue_delayed_work(int cpu
, struct workqueue_struct
*wq
,
1344 struct delayed_work
*dwork
, unsigned long delay
)
1346 struct timer_list
*timer
= &dwork
->timer
;
1347 struct work_struct
*work
= &dwork
->work
;
1350 WARN_ON_ONCE(timer
->function
!= delayed_work_timer_fn
||
1351 timer
->data
!= (unsigned long)dwork
);
1352 BUG_ON(timer_pending(timer
));
1353 BUG_ON(!list_empty(&work
->entry
));
1355 timer_stats_timer_set_start_info(&dwork
->timer
);
1358 * This stores cwq for the moment, for the timer_fn. Note that the
1359 * work's gcwq is preserved to allow reentrance detection for
1362 if (!(wq
->flags
& WQ_UNBOUND
)) {
1363 struct global_cwq
*gcwq
= get_work_gcwq(work
);
1366 * If we cannot get the last gcwq from @work directly,
1367 * select the last CPU such that it avoids unnecessarily
1368 * triggering non-reentrancy check in __queue_work().
1373 if (lcpu
== WORK_CPU_UNBOUND
)
1374 lcpu
= raw_smp_processor_id();
1376 lcpu
= WORK_CPU_UNBOUND
;
1379 set_work_cwq(work
, get_cwq(lcpu
, wq
), 0);
1382 timer
->expires
= jiffies
+ delay
;
1384 if (unlikely(cpu
!= WORK_CPU_UNBOUND
))
1385 add_timer_on(timer
, cpu
);
1391 * queue_delayed_work_on - queue work on specific CPU after delay
1392 * @cpu: CPU number to execute work on
1393 * @wq: workqueue to use
1394 * @dwork: work to queue
1395 * @delay: number of jiffies to wait before queueing
1397 * Returns %false if @work was already on a queue, %true otherwise. If
1398 * @delay is zero and @dwork is idle, it will be scheduled for immediate
1401 bool queue_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1402 struct delayed_work
*dwork
, unsigned long delay
)
1404 struct work_struct
*work
= &dwork
->work
;
1406 unsigned long flags
;
1409 return queue_work_on(cpu
, wq
, &dwork
->work
);
1411 /* read the comment in __queue_work() */
1412 local_irq_save(flags
);
1414 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1415 __queue_delayed_work(cpu
, wq
, dwork
, delay
);
1419 local_irq_restore(flags
);
1422 EXPORT_SYMBOL_GPL(queue_delayed_work_on
);
1425 * queue_delayed_work - queue work on a workqueue after delay
1426 * @wq: workqueue to use
1427 * @dwork: delayable work to queue
1428 * @delay: number of jiffies to wait before queueing
1430 * Equivalent to queue_delayed_work_on() but tries to use the local CPU.
1432 bool queue_delayed_work(struct workqueue_struct
*wq
,
1433 struct delayed_work
*dwork
, unsigned long delay
)
1435 return queue_delayed_work_on(WORK_CPU_UNBOUND
, wq
, dwork
, delay
);
1437 EXPORT_SYMBOL_GPL(queue_delayed_work
);
1440 * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
1441 * @cpu: CPU number to execute work on
1442 * @wq: workqueue to use
1443 * @dwork: work to queue
1444 * @delay: number of jiffies to wait before queueing
1446 * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
1447 * modify @dwork's timer so that it expires after @delay. If @delay is
1448 * zero, @work is guaranteed to be scheduled immediately regardless of its
1451 * Returns %false if @dwork was idle and queued, %true if @dwork was
1452 * pending and its timer was modified.
1454 * This function is safe to call from any context including IRQ handler.
1455 * See try_to_grab_pending() for details.
1457 bool mod_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1458 struct delayed_work
*dwork
, unsigned long delay
)
1460 unsigned long flags
;
1464 ret
= try_to_grab_pending(&dwork
->work
, true, &flags
);
1465 } while (unlikely(ret
== -EAGAIN
));
1467 if (likely(ret
>= 0)) {
1468 __queue_delayed_work(cpu
, wq
, dwork
, delay
);
1469 local_irq_restore(flags
);
1472 /* -ENOENT from try_to_grab_pending() becomes %true */
1475 EXPORT_SYMBOL_GPL(mod_delayed_work_on
);
1478 * mod_delayed_work - modify delay of or queue a delayed work
1479 * @wq: workqueue to use
1480 * @dwork: work to queue
1481 * @delay: number of jiffies to wait before queueing
1483 * mod_delayed_work_on() on local CPU.
1485 bool mod_delayed_work(struct workqueue_struct
*wq
, struct delayed_work
*dwork
,
1486 unsigned long delay
)
1488 return mod_delayed_work_on(WORK_CPU_UNBOUND
, wq
, dwork
, delay
);
1490 EXPORT_SYMBOL_GPL(mod_delayed_work
);
1493 * worker_enter_idle - enter idle state
1494 * @worker: worker which is entering idle state
1496 * @worker is entering idle state. Update stats and idle timer if
1500 * spin_lock_irq(gcwq->lock).
1502 static void worker_enter_idle(struct worker
*worker
)
1504 struct worker_pool
*pool
= worker
->pool
;
1505 struct global_cwq
*gcwq
= pool
->gcwq
;
1507 BUG_ON(worker
->flags
& WORKER_IDLE
);
1508 BUG_ON(!list_empty(&worker
->entry
) &&
1509 (worker
->hentry
.next
|| worker
->hentry
.pprev
));
1511 /* can't use worker_set_flags(), also called from start_worker() */
1512 worker
->flags
|= WORKER_IDLE
;
1514 worker
->last_active
= jiffies
;
1516 /* idle_list is LIFO */
1517 list_add(&worker
->entry
, &pool
->idle_list
);
1519 if (too_many_workers(pool
) && !timer_pending(&pool
->idle_timer
))
1520 mod_timer(&pool
->idle_timer
, jiffies
+ IDLE_WORKER_TIMEOUT
);
1523 * Sanity check nr_running. Because gcwq_unbind_fn() releases
1524 * gcwq->lock between setting %WORKER_UNBOUND and zapping
1525 * nr_running, the warning may trigger spuriously. Check iff
1526 * unbind is not in progress.
1528 WARN_ON_ONCE(!(gcwq
->flags
& GCWQ_DISASSOCIATED
) &&
1529 pool
->nr_workers
== pool
->nr_idle
&&
1530 atomic_read(get_pool_nr_running(pool
)));
1534 * worker_leave_idle - leave idle state
1535 * @worker: worker which is leaving idle state
1537 * @worker is leaving idle state. Update stats.
1540 * spin_lock_irq(gcwq->lock).
1542 static void worker_leave_idle(struct worker
*worker
)
1544 struct worker_pool
*pool
= worker
->pool
;
1546 BUG_ON(!(worker
->flags
& WORKER_IDLE
));
1547 worker_clr_flags(worker
, WORKER_IDLE
);
1549 list_del_init(&worker
->entry
);
1553 * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq
1556 * Works which are scheduled while the cpu is online must at least be
1557 * scheduled to a worker which is bound to the cpu so that if they are
1558 * flushed from cpu callbacks while cpu is going down, they are
1559 * guaranteed to execute on the cpu.
1561 * This function is to be used by rogue workers and rescuers to bind
1562 * themselves to the target cpu and may race with cpu going down or
1563 * coming online. kthread_bind() can't be used because it may put the
1564 * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
1565 * verbatim as it's best effort and blocking and gcwq may be
1566 * [dis]associated in the meantime.
1568 * This function tries set_cpus_allowed() and locks gcwq and verifies the
1569 * binding against %GCWQ_DISASSOCIATED which is set during
1570 * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker
1571 * enters idle state or fetches works without dropping lock, it can
1572 * guarantee the scheduling requirement described in the first paragraph.
1575 * Might sleep. Called without any lock but returns with gcwq->lock
1579 * %true if the associated gcwq is online (@worker is successfully
1580 * bound), %false if offline.
1582 static bool worker_maybe_bind_and_lock(struct worker
*worker
)
1583 __acquires(&gcwq
->lock
)
1585 struct global_cwq
*gcwq
= worker
->pool
->gcwq
;
1586 struct task_struct
*task
= worker
->task
;
1590 * The following call may fail, succeed or succeed
1591 * without actually migrating the task to the cpu if
1592 * it races with cpu hotunplug operation. Verify
1593 * against GCWQ_DISASSOCIATED.
1595 if (!(gcwq
->flags
& GCWQ_DISASSOCIATED
))
1596 set_cpus_allowed_ptr(task
, get_cpu_mask(gcwq
->cpu
));
1598 spin_lock_irq(&gcwq
->lock
);
1599 if (gcwq
->flags
& GCWQ_DISASSOCIATED
)
1601 if (task_cpu(task
) == gcwq
->cpu
&&
1602 cpumask_equal(¤t
->cpus_allowed
,
1603 get_cpu_mask(gcwq
->cpu
)))
1605 spin_unlock_irq(&gcwq
->lock
);
1608 * We've raced with CPU hot[un]plug. Give it a breather
1609 * and retry migration. cond_resched() is required here;
1610 * otherwise, we might deadlock against cpu_stop trying to
1611 * bring down the CPU on non-preemptive kernel.
1619 * Rebind an idle @worker to its CPU. worker_thread() will test
1620 * list_empty(@worker->entry) before leaving idle and call this function.
1622 static void idle_worker_rebind(struct worker
*worker
)
1624 struct global_cwq
*gcwq
= worker
->pool
->gcwq
;
1626 /* CPU may go down again inbetween, clear UNBOUND only on success */
1627 if (worker_maybe_bind_and_lock(worker
))
1628 worker_clr_flags(worker
, WORKER_UNBOUND
);
1630 /* rebind complete, become available again */
1631 list_add(&worker
->entry
, &worker
->pool
->idle_list
);
1632 spin_unlock_irq(&gcwq
->lock
);
1636 * Function for @worker->rebind.work used to rebind unbound busy workers to
1637 * the associated cpu which is coming back online. This is scheduled by
1638 * cpu up but can race with other cpu hotplug operations and may be
1639 * executed twice without intervening cpu down.
1641 static void busy_worker_rebind_fn(struct work_struct
*work
)
1643 struct worker
*worker
= container_of(work
, struct worker
, rebind_work
);
1644 struct global_cwq
*gcwq
= worker
->pool
->gcwq
;
1646 if (worker_maybe_bind_and_lock(worker
))
1647 worker_clr_flags(worker
, WORKER_UNBOUND
);
1649 spin_unlock_irq(&gcwq
->lock
);
1653 * rebind_workers - rebind all workers of a gcwq to the associated CPU
1654 * @gcwq: gcwq of interest
1656 * @gcwq->cpu is coming online. Rebind all workers to the CPU. Rebinding
1657 * is different for idle and busy ones.
1659 * Idle ones will be removed from the idle_list and woken up. They will
1660 * add themselves back after completing rebind. This ensures that the
1661 * idle_list doesn't contain any unbound workers when re-bound busy workers
1662 * try to perform local wake-ups for concurrency management.
1664 * Busy workers can rebind after they finish their current work items.
1665 * Queueing the rebind work item at the head of the scheduled list is
1666 * enough. Note that nr_running will be properly bumped as busy workers
1669 * On return, all non-manager workers are scheduled for rebind - see
1670 * manage_workers() for the manager special case. Any idle worker
1671 * including the manager will not appear on @idle_list until rebind is
1672 * complete, making local wake-ups safe.
1674 static void rebind_workers(struct global_cwq
*gcwq
)
1676 struct worker_pool
*pool
;
1677 struct worker
*worker
, *n
;
1678 struct hlist_node
*pos
;
1681 lockdep_assert_held(&gcwq
->lock
);
1683 for_each_worker_pool(pool
, gcwq
)
1684 lockdep_assert_held(&pool
->assoc_mutex
);
1686 /* dequeue and kick idle ones */
1687 for_each_worker_pool(pool
, gcwq
) {
1688 list_for_each_entry_safe(worker
, n
, &pool
->idle_list
, entry
) {
1690 * idle workers should be off @pool->idle_list
1691 * until rebind is complete to avoid receiving
1692 * premature local wake-ups.
1694 list_del_init(&worker
->entry
);
1697 * worker_thread() will see the above dequeuing
1698 * and call idle_worker_rebind().
1700 wake_up_process(worker
->task
);
1704 /* rebind busy workers */
1705 for_each_busy_worker(worker
, i
, pos
, gcwq
) {
1706 struct work_struct
*rebind_work
= &worker
->rebind_work
;
1707 struct workqueue_struct
*wq
;
1709 if (test_and_set_bit(WORK_STRUCT_PENDING_BIT
,
1710 work_data_bits(rebind_work
)))
1713 debug_work_activate(rebind_work
);
1716 * wq doesn't really matter but let's keep @worker->pool
1717 * and @cwq->pool consistent for sanity.
1719 if (worker_pool_pri(worker
->pool
))
1720 wq
= system_highpri_wq
;
1724 insert_work(get_cwq(gcwq
->cpu
, wq
), rebind_work
,
1725 worker
->scheduled
.next
,
1726 work_color_to_flags(WORK_NO_COLOR
));
1730 static struct worker
*alloc_worker(void)
1732 struct worker
*worker
;
1734 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
1736 INIT_LIST_HEAD(&worker
->entry
);
1737 INIT_LIST_HEAD(&worker
->scheduled
);
1738 INIT_WORK(&worker
->rebind_work
, busy_worker_rebind_fn
);
1739 /* on creation a worker is in !idle && prep state */
1740 worker
->flags
= WORKER_PREP
;
1746 * create_worker - create a new workqueue worker
1747 * @pool: pool the new worker will belong to
1749 * Create a new worker which is bound to @pool. The returned worker
1750 * can be started by calling start_worker() or destroyed using
1754 * Might sleep. Does GFP_KERNEL allocations.
1757 * Pointer to the newly created worker.
1759 static struct worker
*create_worker(struct worker_pool
*pool
)
1761 struct global_cwq
*gcwq
= pool
->gcwq
;
1762 const char *pri
= worker_pool_pri(pool
) ? "H" : "";
1763 struct worker
*worker
= NULL
;
1766 spin_lock_irq(&gcwq
->lock
);
1767 while (ida_get_new(&pool
->worker_ida
, &id
)) {
1768 spin_unlock_irq(&gcwq
->lock
);
1769 if (!ida_pre_get(&pool
->worker_ida
, GFP_KERNEL
))
1771 spin_lock_irq(&gcwq
->lock
);
1773 spin_unlock_irq(&gcwq
->lock
);
1775 worker
= alloc_worker();
1779 worker
->pool
= pool
;
1782 if (gcwq
->cpu
!= WORK_CPU_UNBOUND
)
1783 worker
->task
= kthread_create_on_node(worker_thread
,
1784 worker
, cpu_to_node(gcwq
->cpu
),
1785 "kworker/%u:%d%s", gcwq
->cpu
, id
, pri
);
1787 worker
->task
= kthread_create(worker_thread
, worker
,
1788 "kworker/u:%d%s", id
, pri
);
1789 if (IS_ERR(worker
->task
))
1792 if (worker_pool_pri(pool
))
1793 set_user_nice(worker
->task
, HIGHPRI_NICE_LEVEL
);
1796 * Determine CPU binding of the new worker depending on
1797 * %GCWQ_DISASSOCIATED. The caller is responsible for ensuring the
1798 * flag remains stable across this function. See the comments
1799 * above the flag definition for details.
1801 * As an unbound worker may later become a regular one if CPU comes
1802 * online, make sure every worker has %PF_THREAD_BOUND set.
1804 if (!(gcwq
->flags
& GCWQ_DISASSOCIATED
)) {
1805 kthread_bind(worker
->task
, gcwq
->cpu
);
1807 worker
->task
->flags
|= PF_THREAD_BOUND
;
1808 worker
->flags
|= WORKER_UNBOUND
;
1814 spin_lock_irq(&gcwq
->lock
);
1815 ida_remove(&pool
->worker_ida
, id
);
1816 spin_unlock_irq(&gcwq
->lock
);
1823 * start_worker - start a newly created worker
1824 * @worker: worker to start
1826 * Make the gcwq aware of @worker and start it.
1829 * spin_lock_irq(gcwq->lock).
1831 static void start_worker(struct worker
*worker
)
1833 worker
->flags
|= WORKER_STARTED
;
1834 worker
->pool
->nr_workers
++;
1835 worker_enter_idle(worker
);
1836 wake_up_process(worker
->task
);
1840 * destroy_worker - destroy a workqueue worker
1841 * @worker: worker to be destroyed
1843 * Destroy @worker and adjust @gcwq stats accordingly.
1846 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1848 static void destroy_worker(struct worker
*worker
)
1850 struct worker_pool
*pool
= worker
->pool
;
1851 struct global_cwq
*gcwq
= pool
->gcwq
;
1852 int id
= worker
->id
;
1854 /* sanity check frenzy */
1855 BUG_ON(worker
->current_work
);
1856 BUG_ON(!list_empty(&worker
->scheduled
));
1858 if (worker
->flags
& WORKER_STARTED
)
1860 if (worker
->flags
& WORKER_IDLE
)
1863 list_del_init(&worker
->entry
);
1864 worker
->flags
|= WORKER_DIE
;
1866 spin_unlock_irq(&gcwq
->lock
);
1868 kthread_stop(worker
->task
);
1871 spin_lock_irq(&gcwq
->lock
);
1872 ida_remove(&pool
->worker_ida
, id
);
1875 static void idle_worker_timeout(unsigned long __pool
)
1877 struct worker_pool
*pool
= (void *)__pool
;
1878 struct global_cwq
*gcwq
= pool
->gcwq
;
1880 spin_lock_irq(&gcwq
->lock
);
1882 if (too_many_workers(pool
)) {
1883 struct worker
*worker
;
1884 unsigned long expires
;
1886 /* idle_list is kept in LIFO order, check the last one */
1887 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
1888 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
1890 if (time_before(jiffies
, expires
))
1891 mod_timer(&pool
->idle_timer
, expires
);
1893 /* it's been idle for too long, wake up manager */
1894 pool
->flags
|= POOL_MANAGE_WORKERS
;
1895 wake_up_worker(pool
);
1899 spin_unlock_irq(&gcwq
->lock
);
1902 static bool send_mayday(struct work_struct
*work
)
1904 struct cpu_workqueue_struct
*cwq
= get_work_cwq(work
);
1905 struct workqueue_struct
*wq
= cwq
->wq
;
1908 if (!(wq
->flags
& WQ_RESCUER
))
1911 /* mayday mayday mayday */
1912 cpu
= cwq
->pool
->gcwq
->cpu
;
1913 /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
1914 if (cpu
== WORK_CPU_UNBOUND
)
1916 if (!mayday_test_and_set_cpu(cpu
, wq
->mayday_mask
))
1917 wake_up_process(wq
->rescuer
->task
);
1921 static void gcwq_mayday_timeout(unsigned long __pool
)
1923 struct worker_pool
*pool
= (void *)__pool
;
1924 struct global_cwq
*gcwq
= pool
->gcwq
;
1925 struct work_struct
*work
;
1927 spin_lock_irq(&gcwq
->lock
);
1929 if (need_to_create_worker(pool
)) {
1931 * We've been trying to create a new worker but
1932 * haven't been successful. We might be hitting an
1933 * allocation deadlock. Send distress signals to
1936 list_for_each_entry(work
, &pool
->worklist
, entry
)
1940 spin_unlock_irq(&gcwq
->lock
);
1942 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INTERVAL
);
1946 * maybe_create_worker - create a new worker if necessary
1947 * @pool: pool to create a new worker for
1949 * Create a new worker for @pool if necessary. @pool is guaranteed to
1950 * have at least one idle worker on return from this function. If
1951 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1952 * sent to all rescuers with works scheduled on @pool to resolve
1953 * possible allocation deadlock.
1955 * On return, need_to_create_worker() is guaranteed to be false and
1956 * may_start_working() true.
1959 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1960 * multiple times. Does GFP_KERNEL allocations. Called only from
1964 * false if no action was taken and gcwq->lock stayed locked, true
1967 static bool maybe_create_worker(struct worker_pool
*pool
)
1968 __releases(&gcwq
->lock
)
1969 __acquires(&gcwq
->lock
)
1971 struct global_cwq
*gcwq
= pool
->gcwq
;
1973 if (!need_to_create_worker(pool
))
1976 spin_unlock_irq(&gcwq
->lock
);
1978 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1979 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INITIAL_TIMEOUT
);
1982 struct worker
*worker
;
1984 worker
= create_worker(pool
);
1986 del_timer_sync(&pool
->mayday_timer
);
1987 spin_lock_irq(&gcwq
->lock
);
1988 start_worker(worker
);
1989 BUG_ON(need_to_create_worker(pool
));
1993 if (!need_to_create_worker(pool
))
1996 __set_current_state(TASK_INTERRUPTIBLE
);
1997 schedule_timeout(CREATE_COOLDOWN
);
1999 if (!need_to_create_worker(pool
))
2003 del_timer_sync(&pool
->mayday_timer
);
2004 spin_lock_irq(&gcwq
->lock
);
2005 if (need_to_create_worker(pool
))
2011 * maybe_destroy_worker - destroy workers which have been idle for a while
2012 * @pool: pool to destroy workers for
2014 * Destroy @pool workers which have been idle for longer than
2015 * IDLE_WORKER_TIMEOUT.
2018 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
2019 * multiple times. Called only from manager.
2022 * false if no action was taken and gcwq->lock stayed locked, true
2025 static bool maybe_destroy_workers(struct worker_pool
*pool
)
2029 while (too_many_workers(pool
)) {
2030 struct worker
*worker
;
2031 unsigned long expires
;
2033 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
2034 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
2036 if (time_before(jiffies
, expires
)) {
2037 mod_timer(&pool
->idle_timer
, expires
);
2041 destroy_worker(worker
);
2049 * manage_workers - manage worker pool
2052 * Assume the manager role and manage gcwq worker pool @worker belongs
2053 * to. At any given time, there can be only zero or one manager per
2054 * gcwq. The exclusion is handled automatically by this function.
2056 * The caller can safely start processing works on false return. On
2057 * true return, it's guaranteed that need_to_create_worker() is false
2058 * and may_start_working() is true.
2061 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
2062 * multiple times. Does GFP_KERNEL allocations.
2065 * false if no action was taken and gcwq->lock stayed locked, true if
2066 * some action was taken.
2068 static bool manage_workers(struct worker
*worker
)
2070 struct worker_pool
*pool
= worker
->pool
;
2073 if (pool
->flags
& POOL_MANAGING_WORKERS
)
2076 pool
->flags
|= POOL_MANAGING_WORKERS
;
2079 * To simplify both worker management and CPU hotplug, hold off
2080 * management while hotplug is in progress. CPU hotplug path can't
2081 * grab %POOL_MANAGING_WORKERS to achieve this because that can
2082 * lead to idle worker depletion (all become busy thinking someone
2083 * else is managing) which in turn can result in deadlock under
2084 * extreme circumstances. Use @pool->assoc_mutex to synchronize
2085 * manager against CPU hotplug.
2087 * assoc_mutex would always be free unless CPU hotplug is in
2088 * progress. trylock first without dropping @gcwq->lock.
2090 if (unlikely(!mutex_trylock(&pool
->assoc_mutex
))) {
2091 spin_unlock_irq(&pool
->gcwq
->lock
);
2092 mutex_lock(&pool
->assoc_mutex
);
2094 * CPU hotplug could have happened while we were waiting
2095 * for assoc_mutex. Hotplug itself can't handle us
2096 * because manager isn't either on idle or busy list, and
2097 * @gcwq's state and ours could have deviated.
2099 * As hotplug is now excluded via assoc_mutex, we can
2100 * simply try to bind. It will succeed or fail depending
2101 * on @gcwq's current state. Try it and adjust
2102 * %WORKER_UNBOUND accordingly.
2104 if (worker_maybe_bind_and_lock(worker
))
2105 worker
->flags
&= ~WORKER_UNBOUND
;
2107 worker
->flags
|= WORKER_UNBOUND
;
2112 pool
->flags
&= ~POOL_MANAGE_WORKERS
;
2115 * Destroy and then create so that may_start_working() is true
2118 ret
|= maybe_destroy_workers(pool
);
2119 ret
|= maybe_create_worker(pool
);
2121 pool
->flags
&= ~POOL_MANAGING_WORKERS
;
2122 mutex_unlock(&pool
->assoc_mutex
);
2127 * process_one_work - process single work
2129 * @work: work to process
2131 * Process @work. This function contains all the logics necessary to
2132 * process a single work including synchronization against and
2133 * interaction with other workers on the same cpu, queueing and
2134 * flushing. As long as context requirement is met, any worker can
2135 * call this function to process a work.
2138 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
2140 static void process_one_work(struct worker
*worker
, struct work_struct
*work
)
2141 __releases(&gcwq
->lock
)
2142 __acquires(&gcwq
->lock
)
2144 struct cpu_workqueue_struct
*cwq
= get_work_cwq(work
);
2145 struct worker_pool
*pool
= worker
->pool
;
2146 struct global_cwq
*gcwq
= pool
->gcwq
;
2147 struct hlist_head
*bwh
= busy_worker_head(gcwq
, work
);
2148 bool cpu_intensive
= cwq
->wq
->flags
& WQ_CPU_INTENSIVE
;
2149 work_func_t f
= work
->func
;
2151 struct worker
*collision
;
2152 #ifdef CONFIG_LOCKDEP
2154 * It is permissible to free the struct work_struct from
2155 * inside the function that is called from it, this we need to
2156 * take into account for lockdep too. To avoid bogus "held
2157 * lock freed" warnings as well as problems when looking into
2158 * work->lockdep_map, make a copy and use that here.
2160 struct lockdep_map lockdep_map
;
2162 lockdep_copy_map(&lockdep_map
, &work
->lockdep_map
);
2165 * Ensure we're on the correct CPU. DISASSOCIATED test is
2166 * necessary to avoid spurious warnings from rescuers servicing the
2167 * unbound or a disassociated gcwq.
2169 WARN_ON_ONCE(!(worker
->flags
& WORKER_UNBOUND
) &&
2170 !(gcwq
->flags
& GCWQ_DISASSOCIATED
) &&
2171 raw_smp_processor_id() != gcwq
->cpu
);
2174 * A single work shouldn't be executed concurrently by
2175 * multiple workers on a single cpu. Check whether anyone is
2176 * already processing the work. If so, defer the work to the
2177 * currently executing one.
2179 collision
= __find_worker_executing_work(gcwq
, bwh
, work
);
2180 if (unlikely(collision
)) {
2181 move_linked_works(work
, &collision
->scheduled
, NULL
);
2185 /* claim and dequeue */
2186 debug_work_deactivate(work
);
2187 hlist_add_head(&worker
->hentry
, bwh
);
2188 worker
->current_work
= work
;
2189 worker
->current_cwq
= cwq
;
2190 work_color
= get_work_color(work
);
2192 list_del_init(&work
->entry
);
2195 * CPU intensive works don't participate in concurrency
2196 * management. They're the scheduler's responsibility.
2198 if (unlikely(cpu_intensive
))
2199 worker_set_flags(worker
, WORKER_CPU_INTENSIVE
, true);
2202 * Unbound gcwq isn't concurrency managed and work items should be
2203 * executed ASAP. Wake up another worker if necessary.
2205 if ((worker
->flags
& WORKER_UNBOUND
) && need_more_worker(pool
))
2206 wake_up_worker(pool
);
2209 * Record the last CPU and clear PENDING which should be the last
2210 * update to @work. Also, do this inside @gcwq->lock so that
2211 * PENDING and queued state changes happen together while IRQ is
2214 set_work_cpu_and_clear_pending(work
, gcwq
->cpu
);
2216 spin_unlock_irq(&gcwq
->lock
);
2218 lock_map_acquire_read(&cwq
->wq
->lockdep_map
);
2219 lock_map_acquire(&lockdep_map
);
2220 trace_workqueue_execute_start(work
);
2223 * While we must be careful to not use "work" after this, the trace
2224 * point will only record its address.
2226 trace_workqueue_execute_end(work
);
2227 lock_map_release(&lockdep_map
);
2228 lock_map_release(&cwq
->wq
->lockdep_map
);
2230 if (unlikely(in_atomic() || lockdep_depth(current
) > 0)) {
2231 pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
2232 " last function: %pf\n",
2233 current
->comm
, preempt_count(), task_pid_nr(current
), f
);
2234 debug_show_held_locks(current
);
2238 spin_lock_irq(&gcwq
->lock
);
2240 /* clear cpu intensive status */
2241 if (unlikely(cpu_intensive
))
2242 worker_clr_flags(worker
, WORKER_CPU_INTENSIVE
);
2244 /* we're done with it, release */
2245 hlist_del_init(&worker
->hentry
);
2246 worker
->current_work
= NULL
;
2247 worker
->current_cwq
= NULL
;
2248 cwq_dec_nr_in_flight(cwq
, work_color
, false);
2252 * process_scheduled_works - process scheduled works
2255 * Process all scheduled works. Please note that the scheduled list
2256 * may change while processing a work, so this function repeatedly
2257 * fetches a work from the top and executes it.
2260 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
2263 static void process_scheduled_works(struct worker
*worker
)
2265 while (!list_empty(&worker
->scheduled
)) {
2266 struct work_struct
*work
= list_first_entry(&worker
->scheduled
,
2267 struct work_struct
, entry
);
2268 process_one_work(worker
, work
);
2273 * worker_thread - the worker thread function
2276 * The gcwq worker thread function. There's a single dynamic pool of
2277 * these per each cpu. These workers process all works regardless of
2278 * their specific target workqueue. The only exception is works which
2279 * belong to workqueues with a rescuer which will be explained in
2282 static int worker_thread(void *__worker
)
2284 struct worker
*worker
= __worker
;
2285 struct worker_pool
*pool
= worker
->pool
;
2286 struct global_cwq
*gcwq
= pool
->gcwq
;
2288 /* tell the scheduler that this is a workqueue worker */
2289 worker
->task
->flags
|= PF_WQ_WORKER
;
2291 spin_lock_irq(&gcwq
->lock
);
2293 /* we are off idle list if destruction or rebind is requested */
2294 if (unlikely(list_empty(&worker
->entry
))) {
2295 spin_unlock_irq(&gcwq
->lock
);
2297 /* if DIE is set, destruction is requested */
2298 if (worker
->flags
& WORKER_DIE
) {
2299 worker
->task
->flags
&= ~PF_WQ_WORKER
;
2303 /* otherwise, rebind */
2304 idle_worker_rebind(worker
);
2308 worker_leave_idle(worker
);
2310 /* no more worker necessary? */
2311 if (!need_more_worker(pool
))
2314 /* do we need to manage? */
2315 if (unlikely(!may_start_working(pool
)) && manage_workers(worker
))
2319 * ->scheduled list can only be filled while a worker is
2320 * preparing to process a work or actually processing it.
2321 * Make sure nobody diddled with it while I was sleeping.
2323 BUG_ON(!list_empty(&worker
->scheduled
));
2326 * When control reaches this point, we're guaranteed to have
2327 * at least one idle worker or that someone else has already
2328 * assumed the manager role.
2330 worker_clr_flags(worker
, WORKER_PREP
);
2333 struct work_struct
*work
=
2334 list_first_entry(&pool
->worklist
,
2335 struct work_struct
, entry
);
2337 if (likely(!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))) {
2338 /* optimization path, not strictly necessary */
2339 process_one_work(worker
, work
);
2340 if (unlikely(!list_empty(&worker
->scheduled
)))
2341 process_scheduled_works(worker
);
2343 move_linked_works(work
, &worker
->scheduled
, NULL
);
2344 process_scheduled_works(worker
);
2346 } while (keep_working(pool
));
2348 worker_set_flags(worker
, WORKER_PREP
, false);
2350 if (unlikely(need_to_manage_workers(pool
)) && manage_workers(worker
))
2354 * gcwq->lock is held and there's no work to process and no
2355 * need to manage, sleep. Workers are woken up only while
2356 * holding gcwq->lock or from local cpu, so setting the
2357 * current state before releasing gcwq->lock is enough to
2358 * prevent losing any event.
2360 worker_enter_idle(worker
);
2361 __set_current_state(TASK_INTERRUPTIBLE
);
2362 spin_unlock_irq(&gcwq
->lock
);
2368 * rescuer_thread - the rescuer thread function
2369 * @__wq: the associated workqueue
2371 * Workqueue rescuer thread function. There's one rescuer for each
2372 * workqueue which has WQ_RESCUER set.
2374 * Regular work processing on a gcwq may block trying to create a new
2375 * worker which uses GFP_KERNEL allocation which has slight chance of
2376 * developing into deadlock if some works currently on the same queue
2377 * need to be processed to satisfy the GFP_KERNEL allocation. This is
2378 * the problem rescuer solves.
2380 * When such condition is possible, the gcwq summons rescuers of all
2381 * workqueues which have works queued on the gcwq and let them process
2382 * those works so that forward progress can be guaranteed.
2384 * This should happen rarely.
2386 static int rescuer_thread(void *__wq
)
2388 struct workqueue_struct
*wq
= __wq
;
2389 struct worker
*rescuer
= wq
->rescuer
;
2390 struct list_head
*scheduled
= &rescuer
->scheduled
;
2391 bool is_unbound
= wq
->flags
& WQ_UNBOUND
;
2394 set_user_nice(current
, RESCUER_NICE_LEVEL
);
2396 set_current_state(TASK_INTERRUPTIBLE
);
2398 if (kthread_should_stop())
2402 * See whether any cpu is asking for help. Unbounded
2403 * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND.
2405 for_each_mayday_cpu(cpu
, wq
->mayday_mask
) {
2406 unsigned int tcpu
= is_unbound
? WORK_CPU_UNBOUND
: cpu
;
2407 struct cpu_workqueue_struct
*cwq
= get_cwq(tcpu
, wq
);
2408 struct worker_pool
*pool
= cwq
->pool
;
2409 struct global_cwq
*gcwq
= pool
->gcwq
;
2410 struct work_struct
*work
, *n
;
2412 __set_current_state(TASK_RUNNING
);
2413 mayday_clear_cpu(cpu
, wq
->mayday_mask
);
2415 /* migrate to the target cpu if possible */
2416 rescuer
->pool
= pool
;
2417 worker_maybe_bind_and_lock(rescuer
);
2420 * Slurp in all works issued via this workqueue and
2423 BUG_ON(!list_empty(&rescuer
->scheduled
));
2424 list_for_each_entry_safe(work
, n
, &pool
->worklist
, entry
)
2425 if (get_work_cwq(work
) == cwq
)
2426 move_linked_works(work
, scheduled
, &n
);
2428 process_scheduled_works(rescuer
);
2431 * Leave this gcwq. If keep_working() is %true, notify a
2432 * regular worker; otherwise, we end up with 0 concurrency
2433 * and stalling the execution.
2435 if (keep_working(pool
))
2436 wake_up_worker(pool
);
2438 spin_unlock_irq(&gcwq
->lock
);
2446 struct work_struct work
;
2447 struct completion done
;
2450 static void wq_barrier_func(struct work_struct
*work
)
2452 struct wq_barrier
*barr
= container_of(work
, struct wq_barrier
, work
);
2453 complete(&barr
->done
);
2457 * insert_wq_barrier - insert a barrier work
2458 * @cwq: cwq to insert barrier into
2459 * @barr: wq_barrier to insert
2460 * @target: target work to attach @barr to
2461 * @worker: worker currently executing @target, NULL if @target is not executing
2463 * @barr is linked to @target such that @barr is completed only after
2464 * @target finishes execution. Please note that the ordering
2465 * guarantee is observed only with respect to @target and on the local
2468 * Currently, a queued barrier can't be canceled. This is because
2469 * try_to_grab_pending() can't determine whether the work to be
2470 * grabbed is at the head of the queue and thus can't clear LINKED
2471 * flag of the previous work while there must be a valid next work
2472 * after a work with LINKED flag set.
2474 * Note that when @worker is non-NULL, @target may be modified
2475 * underneath us, so we can't reliably determine cwq from @target.
2478 * spin_lock_irq(gcwq->lock).
2480 static void insert_wq_barrier(struct cpu_workqueue_struct
*cwq
,
2481 struct wq_barrier
*barr
,
2482 struct work_struct
*target
, struct worker
*worker
)
2484 struct list_head
*head
;
2485 unsigned int linked
= 0;
2488 * debugobject calls are safe here even with gcwq->lock locked
2489 * as we know for sure that this will not trigger any of the
2490 * checks and call back into the fixup functions where we
2493 INIT_WORK_ONSTACK(&barr
->work
, wq_barrier_func
);
2494 __set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(&barr
->work
));
2495 init_completion(&barr
->done
);
2498 * If @target is currently being executed, schedule the
2499 * barrier to the worker; otherwise, put it after @target.
2502 head
= worker
->scheduled
.next
;
2504 unsigned long *bits
= work_data_bits(target
);
2506 head
= target
->entry
.next
;
2507 /* there can already be other linked works, inherit and set */
2508 linked
= *bits
& WORK_STRUCT_LINKED
;
2509 __set_bit(WORK_STRUCT_LINKED_BIT
, bits
);
2512 debug_work_activate(&barr
->work
);
2513 insert_work(cwq
, &barr
->work
, head
,
2514 work_color_to_flags(WORK_NO_COLOR
) | linked
);
2518 * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing
2519 * @wq: workqueue being flushed
2520 * @flush_color: new flush color, < 0 for no-op
2521 * @work_color: new work color, < 0 for no-op
2523 * Prepare cwqs for workqueue flushing.
2525 * If @flush_color is non-negative, flush_color on all cwqs should be
2526 * -1. If no cwq has in-flight commands at the specified color, all
2527 * cwq->flush_color's stay at -1 and %false is returned. If any cwq
2528 * has in flight commands, its cwq->flush_color is set to
2529 * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq
2530 * wakeup logic is armed and %true is returned.
2532 * The caller should have initialized @wq->first_flusher prior to
2533 * calling this function with non-negative @flush_color. If
2534 * @flush_color is negative, no flush color update is done and %false
2537 * If @work_color is non-negative, all cwqs should have the same
2538 * work_color which is previous to @work_color and all will be
2539 * advanced to @work_color.
2542 * mutex_lock(wq->flush_mutex).
2545 * %true if @flush_color >= 0 and there's something to flush. %false
2548 static bool flush_workqueue_prep_cwqs(struct workqueue_struct
*wq
,
2549 int flush_color
, int work_color
)
2554 if (flush_color
>= 0) {
2555 BUG_ON(atomic_read(&wq
->nr_cwqs_to_flush
));
2556 atomic_set(&wq
->nr_cwqs_to_flush
, 1);
2559 for_each_cwq_cpu(cpu
, wq
) {
2560 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
2561 struct global_cwq
*gcwq
= cwq
->pool
->gcwq
;
2563 spin_lock_irq(&gcwq
->lock
);
2565 if (flush_color
>= 0) {
2566 BUG_ON(cwq
->flush_color
!= -1);
2568 if (cwq
->nr_in_flight
[flush_color
]) {
2569 cwq
->flush_color
= flush_color
;
2570 atomic_inc(&wq
->nr_cwqs_to_flush
);
2575 if (work_color
>= 0) {
2576 BUG_ON(work_color
!= work_next_color(cwq
->work_color
));
2577 cwq
->work_color
= work_color
;
2580 spin_unlock_irq(&gcwq
->lock
);
2583 if (flush_color
>= 0 && atomic_dec_and_test(&wq
->nr_cwqs_to_flush
))
2584 complete(&wq
->first_flusher
->done
);
2590 * flush_workqueue - ensure that any scheduled work has run to completion.
2591 * @wq: workqueue to flush
2593 * Forces execution of the workqueue and blocks until its completion.
2594 * This is typically used in driver shutdown handlers.
2596 * We sleep until all works which were queued on entry have been handled,
2597 * but we are not livelocked by new incoming ones.
2599 void flush_workqueue(struct workqueue_struct
*wq
)
2601 struct wq_flusher this_flusher
= {
2602 .list
= LIST_HEAD_INIT(this_flusher
.list
),
2604 .done
= COMPLETION_INITIALIZER_ONSTACK(this_flusher
.done
),
2608 lock_map_acquire(&wq
->lockdep_map
);
2609 lock_map_release(&wq
->lockdep_map
);
2611 mutex_lock(&wq
->flush_mutex
);
2614 * Start-to-wait phase
2616 next_color
= work_next_color(wq
->work_color
);
2618 if (next_color
!= wq
->flush_color
) {
2620 * Color space is not full. The current work_color
2621 * becomes our flush_color and work_color is advanced
2624 BUG_ON(!list_empty(&wq
->flusher_overflow
));
2625 this_flusher
.flush_color
= wq
->work_color
;
2626 wq
->work_color
= next_color
;
2628 if (!wq
->first_flusher
) {
2629 /* no flush in progress, become the first flusher */
2630 BUG_ON(wq
->flush_color
!= this_flusher
.flush_color
);
2632 wq
->first_flusher
= &this_flusher
;
2634 if (!flush_workqueue_prep_cwqs(wq
, wq
->flush_color
,
2636 /* nothing to flush, done */
2637 wq
->flush_color
= next_color
;
2638 wq
->first_flusher
= NULL
;
2643 BUG_ON(wq
->flush_color
== this_flusher
.flush_color
);
2644 list_add_tail(&this_flusher
.list
, &wq
->flusher_queue
);
2645 flush_workqueue_prep_cwqs(wq
, -1, wq
->work_color
);
2649 * Oops, color space is full, wait on overflow queue.
2650 * The next flush completion will assign us
2651 * flush_color and transfer to flusher_queue.
2653 list_add_tail(&this_flusher
.list
, &wq
->flusher_overflow
);
2656 mutex_unlock(&wq
->flush_mutex
);
2658 wait_for_completion(&this_flusher
.done
);
2661 * Wake-up-and-cascade phase
2663 * First flushers are responsible for cascading flushes and
2664 * handling overflow. Non-first flushers can simply return.
2666 if (wq
->first_flusher
!= &this_flusher
)
2669 mutex_lock(&wq
->flush_mutex
);
2671 /* we might have raced, check again with mutex held */
2672 if (wq
->first_flusher
!= &this_flusher
)
2675 wq
->first_flusher
= NULL
;
2677 BUG_ON(!list_empty(&this_flusher
.list
));
2678 BUG_ON(wq
->flush_color
!= this_flusher
.flush_color
);
2681 struct wq_flusher
*next
, *tmp
;
2683 /* complete all the flushers sharing the current flush color */
2684 list_for_each_entry_safe(next
, tmp
, &wq
->flusher_queue
, list
) {
2685 if (next
->flush_color
!= wq
->flush_color
)
2687 list_del_init(&next
->list
);
2688 complete(&next
->done
);
2691 BUG_ON(!list_empty(&wq
->flusher_overflow
) &&
2692 wq
->flush_color
!= work_next_color(wq
->work_color
));
2694 /* this flush_color is finished, advance by one */
2695 wq
->flush_color
= work_next_color(wq
->flush_color
);
2697 /* one color has been freed, handle overflow queue */
2698 if (!list_empty(&wq
->flusher_overflow
)) {
2700 * Assign the same color to all overflowed
2701 * flushers, advance work_color and append to
2702 * flusher_queue. This is the start-to-wait
2703 * phase for these overflowed flushers.
2705 list_for_each_entry(tmp
, &wq
->flusher_overflow
, list
)
2706 tmp
->flush_color
= wq
->work_color
;
2708 wq
->work_color
= work_next_color(wq
->work_color
);
2710 list_splice_tail_init(&wq
->flusher_overflow
,
2711 &wq
->flusher_queue
);
2712 flush_workqueue_prep_cwqs(wq
, -1, wq
->work_color
);
2715 if (list_empty(&wq
->flusher_queue
)) {
2716 BUG_ON(wq
->flush_color
!= wq
->work_color
);
2721 * Need to flush more colors. Make the next flusher
2722 * the new first flusher and arm cwqs.
2724 BUG_ON(wq
->flush_color
== wq
->work_color
);
2725 BUG_ON(wq
->flush_color
!= next
->flush_color
);
2727 list_del_init(&next
->list
);
2728 wq
->first_flusher
= next
;
2730 if (flush_workqueue_prep_cwqs(wq
, wq
->flush_color
, -1))
2734 * Meh... this color is already done, clear first
2735 * flusher and repeat cascading.
2737 wq
->first_flusher
= NULL
;
2741 mutex_unlock(&wq
->flush_mutex
);
2743 EXPORT_SYMBOL_GPL(flush_workqueue
);
2746 * drain_workqueue - drain a workqueue
2747 * @wq: workqueue to drain
2749 * Wait until the workqueue becomes empty. While draining is in progress,
2750 * only chain queueing is allowed. IOW, only currently pending or running
2751 * work items on @wq can queue further work items on it. @wq is flushed
2752 * repeatedly until it becomes empty. The number of flushing is detemined
2753 * by the depth of chaining and should be relatively short. Whine if it
2756 void drain_workqueue(struct workqueue_struct
*wq
)
2758 unsigned int flush_cnt
= 0;
2762 * __queue_work() needs to test whether there are drainers, is much
2763 * hotter than drain_workqueue() and already looks at @wq->flags.
2764 * Use WQ_DRAINING so that queue doesn't have to check nr_drainers.
2766 spin_lock(&workqueue_lock
);
2767 if (!wq
->nr_drainers
++)
2768 wq
->flags
|= WQ_DRAINING
;
2769 spin_unlock(&workqueue_lock
);
2771 flush_workqueue(wq
);
2773 for_each_cwq_cpu(cpu
, wq
) {
2774 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
2777 spin_lock_irq(&cwq
->pool
->gcwq
->lock
);
2778 drained
= !cwq
->nr_active
&& list_empty(&cwq
->delayed_works
);
2779 spin_unlock_irq(&cwq
->pool
->gcwq
->lock
);
2784 if (++flush_cnt
== 10 ||
2785 (flush_cnt
% 100 == 0 && flush_cnt
<= 1000))
2786 pr_warn("workqueue %s: flush on destruction isn't complete after %u tries\n",
2787 wq
->name
, flush_cnt
);
2791 spin_lock(&workqueue_lock
);
2792 if (!--wq
->nr_drainers
)
2793 wq
->flags
&= ~WQ_DRAINING
;
2794 spin_unlock(&workqueue_lock
);
2796 EXPORT_SYMBOL_GPL(drain_workqueue
);
2798 static bool start_flush_work(struct work_struct
*work
, struct wq_barrier
*barr
)
2800 struct worker
*worker
= NULL
;
2801 struct global_cwq
*gcwq
;
2802 struct cpu_workqueue_struct
*cwq
;
2805 gcwq
= get_work_gcwq(work
);
2809 spin_lock_irq(&gcwq
->lock
);
2810 if (!list_empty(&work
->entry
)) {
2812 * See the comment near try_to_grab_pending()->smp_rmb().
2813 * If it was re-queued to a different gcwq under us, we
2814 * are not going to wait.
2817 cwq
= get_work_cwq(work
);
2818 if (unlikely(!cwq
|| gcwq
!= cwq
->pool
->gcwq
))
2821 worker
= find_worker_executing_work(gcwq
, work
);
2824 cwq
= worker
->current_cwq
;
2827 insert_wq_barrier(cwq
, barr
, work
, worker
);
2828 spin_unlock_irq(&gcwq
->lock
);
2831 * If @max_active is 1 or rescuer is in use, flushing another work
2832 * item on the same workqueue may lead to deadlock. Make sure the
2833 * flusher is not running on the same workqueue by verifying write
2836 if (cwq
->wq
->saved_max_active
== 1 || cwq
->wq
->flags
& WQ_RESCUER
)
2837 lock_map_acquire(&cwq
->wq
->lockdep_map
);
2839 lock_map_acquire_read(&cwq
->wq
->lockdep_map
);
2840 lock_map_release(&cwq
->wq
->lockdep_map
);
2844 spin_unlock_irq(&gcwq
->lock
);
2849 * flush_work - wait for a work to finish executing the last queueing instance
2850 * @work: the work to flush
2852 * Wait until @work has finished execution. @work is guaranteed to be idle
2853 * on return if it hasn't been requeued since flush started.
2856 * %true if flush_work() waited for the work to finish execution,
2857 * %false if it was already idle.
2859 bool flush_work(struct work_struct
*work
)
2861 struct wq_barrier barr
;
2863 lock_map_acquire(&work
->lockdep_map
);
2864 lock_map_release(&work
->lockdep_map
);
2866 if (start_flush_work(work
, &barr
)) {
2867 wait_for_completion(&barr
.done
);
2868 destroy_work_on_stack(&barr
.work
);
2874 EXPORT_SYMBOL_GPL(flush_work
);
2876 static bool __cancel_work_timer(struct work_struct
*work
, bool is_dwork
)
2878 unsigned long flags
;
2882 ret
= try_to_grab_pending(work
, is_dwork
, &flags
);
2884 * If someone else is canceling, wait for the same event it
2885 * would be waiting for before retrying.
2887 if (unlikely(ret
== -ENOENT
))
2889 } while (unlikely(ret
< 0));
2891 /* tell other tasks trying to grab @work to back off */
2892 mark_work_canceling(work
);
2893 local_irq_restore(flags
);
2896 clear_work_data(work
);
2901 * cancel_work_sync - cancel a work and wait for it to finish
2902 * @work: the work to cancel
2904 * Cancel @work and wait for its execution to finish. This function
2905 * can be used even if the work re-queues itself or migrates to
2906 * another workqueue. On return from this function, @work is
2907 * guaranteed to be not pending or executing on any CPU.
2909 * cancel_work_sync(&delayed_work->work) must not be used for
2910 * delayed_work's. Use cancel_delayed_work_sync() instead.
2912 * The caller must ensure that the workqueue on which @work was last
2913 * queued can't be destroyed before this function returns.
2916 * %true if @work was pending, %false otherwise.
2918 bool cancel_work_sync(struct work_struct
*work
)
2920 return __cancel_work_timer(work
, false);
2922 EXPORT_SYMBOL_GPL(cancel_work_sync
);
2925 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2926 * @dwork: the delayed work to flush
2928 * Delayed timer is cancelled and the pending work is queued for
2929 * immediate execution. Like flush_work(), this function only
2930 * considers the last queueing instance of @dwork.
2933 * %true if flush_work() waited for the work to finish execution,
2934 * %false if it was already idle.
2936 bool flush_delayed_work(struct delayed_work
*dwork
)
2938 local_irq_disable();
2939 if (del_timer_sync(&dwork
->timer
))
2940 __queue_work(dwork
->cpu
,
2941 get_work_cwq(&dwork
->work
)->wq
, &dwork
->work
);
2943 return flush_work(&dwork
->work
);
2945 EXPORT_SYMBOL(flush_delayed_work
);
2948 * cancel_delayed_work - cancel a delayed work
2949 * @dwork: delayed_work to cancel
2951 * Kill off a pending delayed_work. Returns %true if @dwork was pending
2952 * and canceled; %false if wasn't pending. Note that the work callback
2953 * function may still be running on return, unless it returns %true and the
2954 * work doesn't re-arm itself. Explicitly flush or use
2955 * cancel_delayed_work_sync() to wait on it.
2957 * This function is safe to call from any context including IRQ handler.
2959 bool cancel_delayed_work(struct delayed_work
*dwork
)
2961 unsigned long flags
;
2965 ret
= try_to_grab_pending(&dwork
->work
, true, &flags
);
2966 } while (unlikely(ret
== -EAGAIN
));
2968 if (unlikely(ret
< 0))
2971 set_work_cpu_and_clear_pending(&dwork
->work
, work_cpu(&dwork
->work
));
2972 local_irq_restore(flags
);
2975 EXPORT_SYMBOL(cancel_delayed_work
);
2978 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
2979 * @dwork: the delayed work cancel
2981 * This is cancel_work_sync() for delayed works.
2984 * %true if @dwork was pending, %false otherwise.
2986 bool cancel_delayed_work_sync(struct delayed_work
*dwork
)
2988 return __cancel_work_timer(&dwork
->work
, true);
2990 EXPORT_SYMBOL(cancel_delayed_work_sync
);
2993 * schedule_work_on - put work task on a specific cpu
2994 * @cpu: cpu to put the work task on
2995 * @work: job to be done
2997 * This puts a job on a specific cpu
2999 bool schedule_work_on(int cpu
, struct work_struct
*work
)
3001 return queue_work_on(cpu
, system_wq
, work
);
3003 EXPORT_SYMBOL(schedule_work_on
);
3006 * schedule_work - put work task in global workqueue
3007 * @work: job to be done
3009 * Returns %false if @work was already on the kernel-global workqueue and
3012 * This puts a job in the kernel-global workqueue if it was not already
3013 * queued and leaves it in the same position on the kernel-global
3014 * workqueue otherwise.
3016 bool schedule_work(struct work_struct
*work
)
3018 return queue_work(system_wq
, work
);
3020 EXPORT_SYMBOL(schedule_work
);
3023 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
3025 * @dwork: job to be done
3026 * @delay: number of jiffies to wait
3028 * After waiting for a given time this puts a job in the kernel-global
3029 * workqueue on the specified CPU.
3031 bool schedule_delayed_work_on(int cpu
, struct delayed_work
*dwork
,
3032 unsigned long delay
)
3034 return queue_delayed_work_on(cpu
, system_wq
, dwork
, delay
);
3036 EXPORT_SYMBOL(schedule_delayed_work_on
);
3039 * schedule_delayed_work - put work task in global workqueue after delay
3040 * @dwork: job to be done
3041 * @delay: number of jiffies to wait or 0 for immediate execution
3043 * After waiting for a given time this puts a job in the kernel-global
3046 bool schedule_delayed_work(struct delayed_work
*dwork
, unsigned long delay
)
3048 return queue_delayed_work(system_wq
, dwork
, delay
);
3050 EXPORT_SYMBOL(schedule_delayed_work
);
3053 * schedule_on_each_cpu - execute a function synchronously on each online CPU
3054 * @func: the function to call
3056 * schedule_on_each_cpu() executes @func on each online CPU using the
3057 * system workqueue and blocks until all CPUs have completed.
3058 * schedule_on_each_cpu() is very slow.
3061 * 0 on success, -errno on failure.
3063 int schedule_on_each_cpu(work_func_t func
)
3066 struct work_struct __percpu
*works
;
3068 works
= alloc_percpu(struct work_struct
);
3074 for_each_online_cpu(cpu
) {
3075 struct work_struct
*work
= per_cpu_ptr(works
, cpu
);
3077 INIT_WORK(work
, func
);
3078 schedule_work_on(cpu
, work
);
3081 for_each_online_cpu(cpu
)
3082 flush_work(per_cpu_ptr(works
, cpu
));
3090 * flush_scheduled_work - ensure that any scheduled work has run to completion.
3092 * Forces execution of the kernel-global workqueue and blocks until its
3095 * Think twice before calling this function! It's very easy to get into
3096 * trouble if you don't take great care. Either of the following situations
3097 * will lead to deadlock:
3099 * One of the work items currently on the workqueue needs to acquire
3100 * a lock held by your code or its caller.
3102 * Your code is running in the context of a work routine.
3104 * They will be detected by lockdep when they occur, but the first might not
3105 * occur very often. It depends on what work items are on the workqueue and
3106 * what locks they need, which you have no control over.
3108 * In most situations flushing the entire workqueue is overkill; you merely
3109 * need to know that a particular work item isn't queued and isn't running.
3110 * In such cases you should use cancel_delayed_work_sync() or
3111 * cancel_work_sync() instead.
3113 void flush_scheduled_work(void)
3115 flush_workqueue(system_wq
);
3117 EXPORT_SYMBOL(flush_scheduled_work
);
3120 * execute_in_process_context - reliably execute the routine with user context
3121 * @fn: the function to execute
3122 * @ew: guaranteed storage for the execute work structure (must
3123 * be available when the work executes)
3125 * Executes the function immediately if process context is available,
3126 * otherwise schedules the function for delayed execution.
3128 * Returns: 0 - function was executed
3129 * 1 - function was scheduled for execution
3131 int execute_in_process_context(work_func_t fn
, struct execute_work
*ew
)
3133 if (!in_interrupt()) {
3138 INIT_WORK(&ew
->work
, fn
);
3139 schedule_work(&ew
->work
);
3143 EXPORT_SYMBOL_GPL(execute_in_process_context
);
3145 int keventd_up(void)
3147 return system_wq
!= NULL
;
3150 static int alloc_cwqs(struct workqueue_struct
*wq
)
3153 * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
3154 * Make sure that the alignment isn't lower than that of
3155 * unsigned long long.
3157 const size_t size
= sizeof(struct cpu_workqueue_struct
);
3158 const size_t align
= max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS
,
3159 __alignof__(unsigned long long));
3161 if (!(wq
->flags
& WQ_UNBOUND
))
3162 wq
->cpu_wq
.pcpu
= __alloc_percpu(size
, align
);
3167 * Allocate enough room to align cwq and put an extra
3168 * pointer at the end pointing back to the originally
3169 * allocated pointer which will be used for free.
3171 ptr
= kzalloc(size
+ align
+ sizeof(void *), GFP_KERNEL
);
3173 wq
->cpu_wq
.single
= PTR_ALIGN(ptr
, align
);
3174 *(void **)(wq
->cpu_wq
.single
+ 1) = ptr
;
3178 /* just in case, make sure it's actually aligned */
3179 BUG_ON(!IS_ALIGNED(wq
->cpu_wq
.v
, align
));
3180 return wq
->cpu_wq
.v
? 0 : -ENOMEM
;
3183 static void free_cwqs(struct workqueue_struct
*wq
)
3185 if (!(wq
->flags
& WQ_UNBOUND
))
3186 free_percpu(wq
->cpu_wq
.pcpu
);
3187 else if (wq
->cpu_wq
.single
) {
3188 /* the pointer to free is stored right after the cwq */
3189 kfree(*(void **)(wq
->cpu_wq
.single
+ 1));
3193 static int wq_clamp_max_active(int max_active
, unsigned int flags
,
3196 int lim
= flags
& WQ_UNBOUND
? WQ_UNBOUND_MAX_ACTIVE
: WQ_MAX_ACTIVE
;
3198 if (max_active
< 1 || max_active
> lim
)
3199 pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
3200 max_active
, name
, 1, lim
);
3202 return clamp_val(max_active
, 1, lim
);
3205 struct workqueue_struct
*__alloc_workqueue_key(const char *fmt
,
3208 struct lock_class_key
*key
,
3209 const char *lock_name
, ...)
3211 va_list args
, args1
;
3212 struct workqueue_struct
*wq
;
3216 /* determine namelen, allocate wq and format name */
3217 va_start(args
, lock_name
);
3218 va_copy(args1
, args
);
3219 namelen
= vsnprintf(NULL
, 0, fmt
, args
) + 1;
3221 wq
= kzalloc(sizeof(*wq
) + namelen
, GFP_KERNEL
);
3225 vsnprintf(wq
->name
, namelen
, fmt
, args1
);
3230 * Workqueues which may be used during memory reclaim should
3231 * have a rescuer to guarantee forward progress.
3233 if (flags
& WQ_MEM_RECLAIM
)
3234 flags
|= WQ_RESCUER
;
3236 max_active
= max_active
?: WQ_DFL_ACTIVE
;
3237 max_active
= wq_clamp_max_active(max_active
, flags
, wq
->name
);
3241 wq
->saved_max_active
= max_active
;
3242 mutex_init(&wq
->flush_mutex
);
3243 atomic_set(&wq
->nr_cwqs_to_flush
, 0);
3244 INIT_LIST_HEAD(&wq
->flusher_queue
);
3245 INIT_LIST_HEAD(&wq
->flusher_overflow
);
3247 lockdep_init_map(&wq
->lockdep_map
, lock_name
, key
, 0);
3248 INIT_LIST_HEAD(&wq
->list
);
3250 if (alloc_cwqs(wq
) < 0)
3253 for_each_cwq_cpu(cpu
, wq
) {
3254 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3255 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3256 int pool_idx
= (bool)(flags
& WQ_HIGHPRI
);
3258 BUG_ON((unsigned long)cwq
& WORK_STRUCT_FLAG_MASK
);
3259 cwq
->pool
= &gcwq
->pools
[pool_idx
];
3261 cwq
->flush_color
= -1;
3262 cwq
->max_active
= max_active
;
3263 INIT_LIST_HEAD(&cwq
->delayed_works
);
3266 if (flags
& WQ_RESCUER
) {
3267 struct worker
*rescuer
;
3269 if (!alloc_mayday_mask(&wq
->mayday_mask
, GFP_KERNEL
))
3272 wq
->rescuer
= rescuer
= alloc_worker();
3276 rescuer
->task
= kthread_create(rescuer_thread
, wq
, "%s",
3278 if (IS_ERR(rescuer
->task
))
3281 rescuer
->task
->flags
|= PF_THREAD_BOUND
;
3282 wake_up_process(rescuer
->task
);
3286 * workqueue_lock protects global freeze state and workqueues
3287 * list. Grab it, set max_active accordingly and add the new
3288 * workqueue to workqueues list.
3290 spin_lock(&workqueue_lock
);
3292 if (workqueue_freezing
&& wq
->flags
& WQ_FREEZABLE
)
3293 for_each_cwq_cpu(cpu
, wq
)
3294 get_cwq(cpu
, wq
)->max_active
= 0;
3296 list_add(&wq
->list
, &workqueues
);
3298 spin_unlock(&workqueue_lock
);
3304 free_mayday_mask(wq
->mayday_mask
);
3310 EXPORT_SYMBOL_GPL(__alloc_workqueue_key
);
3313 * destroy_workqueue - safely terminate a workqueue
3314 * @wq: target workqueue
3316 * Safely destroy a workqueue. All work currently pending will be done first.
3318 void destroy_workqueue(struct workqueue_struct
*wq
)
3322 /* drain it before proceeding with destruction */
3323 drain_workqueue(wq
);
3326 * wq list is used to freeze wq, remove from list after
3327 * flushing is complete in case freeze races us.
3329 spin_lock(&workqueue_lock
);
3330 list_del(&wq
->list
);
3331 spin_unlock(&workqueue_lock
);
3334 for_each_cwq_cpu(cpu
, wq
) {
3335 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3338 for (i
= 0; i
< WORK_NR_COLORS
; i
++)
3339 BUG_ON(cwq
->nr_in_flight
[i
]);
3340 BUG_ON(cwq
->nr_active
);
3341 BUG_ON(!list_empty(&cwq
->delayed_works
));
3344 if (wq
->flags
& WQ_RESCUER
) {
3345 kthread_stop(wq
->rescuer
->task
);
3346 free_mayday_mask(wq
->mayday_mask
);
3353 EXPORT_SYMBOL_GPL(destroy_workqueue
);
3356 * workqueue_set_max_active - adjust max_active of a workqueue
3357 * @wq: target workqueue
3358 * @max_active: new max_active value.
3360 * Set max_active of @wq to @max_active.
3363 * Don't call from IRQ context.
3365 void workqueue_set_max_active(struct workqueue_struct
*wq
, int max_active
)
3369 max_active
= wq_clamp_max_active(max_active
, wq
->flags
, wq
->name
);
3371 spin_lock(&workqueue_lock
);
3373 wq
->saved_max_active
= max_active
;
3375 for_each_cwq_cpu(cpu
, wq
) {
3376 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3378 spin_lock_irq(&gcwq
->lock
);
3380 if (!(wq
->flags
& WQ_FREEZABLE
) ||
3381 !(gcwq
->flags
& GCWQ_FREEZING
))
3382 get_cwq(gcwq
->cpu
, wq
)->max_active
= max_active
;
3384 spin_unlock_irq(&gcwq
->lock
);
3387 spin_unlock(&workqueue_lock
);
3389 EXPORT_SYMBOL_GPL(workqueue_set_max_active
);
3392 * workqueue_congested - test whether a workqueue is congested
3393 * @cpu: CPU in question
3394 * @wq: target workqueue
3396 * Test whether @wq's cpu workqueue for @cpu is congested. There is
3397 * no synchronization around this function and the test result is
3398 * unreliable and only useful as advisory hints or for debugging.
3401 * %true if congested, %false otherwise.
3403 bool workqueue_congested(unsigned int cpu
, struct workqueue_struct
*wq
)
3405 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3407 return !list_empty(&cwq
->delayed_works
);
3409 EXPORT_SYMBOL_GPL(workqueue_congested
);
3412 * work_cpu - return the last known associated cpu for @work
3413 * @work: the work of interest
3416 * CPU number if @work was ever queued. WORK_CPU_NONE otherwise.
3418 unsigned int work_cpu(struct work_struct
*work
)
3420 struct global_cwq
*gcwq
= get_work_gcwq(work
);
3422 return gcwq
? gcwq
->cpu
: WORK_CPU_NONE
;
3424 EXPORT_SYMBOL_GPL(work_cpu
);
3427 * work_busy - test whether a work is currently pending or running
3428 * @work: the work to be tested
3430 * Test whether @work is currently pending or running. There is no
3431 * synchronization around this function and the test result is
3432 * unreliable and only useful as advisory hints or for debugging.
3433 * Especially for reentrant wqs, the pending state might hide the
3437 * OR'd bitmask of WORK_BUSY_* bits.
3439 unsigned int work_busy(struct work_struct
*work
)
3441 struct global_cwq
*gcwq
= get_work_gcwq(work
);
3442 unsigned long flags
;
3443 unsigned int ret
= 0;
3448 spin_lock_irqsave(&gcwq
->lock
, flags
);
3450 if (work_pending(work
))
3451 ret
|= WORK_BUSY_PENDING
;
3452 if (find_worker_executing_work(gcwq
, work
))
3453 ret
|= WORK_BUSY_RUNNING
;
3455 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
3459 EXPORT_SYMBOL_GPL(work_busy
);
3464 * There are two challenges in supporting CPU hotplug. Firstly, there
3465 * are a lot of assumptions on strong associations among work, cwq and
3466 * gcwq which make migrating pending and scheduled works very
3467 * difficult to implement without impacting hot paths. Secondly,
3468 * gcwqs serve mix of short, long and very long running works making
3469 * blocked draining impractical.
3471 * This is solved by allowing a gcwq to be disassociated from the CPU
3472 * running as an unbound one and allowing it to be reattached later if the
3473 * cpu comes back online.
3476 /* claim manager positions of all pools */
3477 static void gcwq_claim_assoc_and_lock(struct global_cwq
*gcwq
)
3479 struct worker_pool
*pool
;
3481 for_each_worker_pool(pool
, gcwq
)
3482 mutex_lock_nested(&pool
->assoc_mutex
, pool
- gcwq
->pools
);
3483 spin_lock_irq(&gcwq
->lock
);
3486 /* release manager positions */
3487 static void gcwq_release_assoc_and_unlock(struct global_cwq
*gcwq
)
3489 struct worker_pool
*pool
;
3491 spin_unlock_irq(&gcwq
->lock
);
3492 for_each_worker_pool(pool
, gcwq
)
3493 mutex_unlock(&pool
->assoc_mutex
);
3496 static void gcwq_unbind_fn(struct work_struct
*work
)
3498 struct global_cwq
*gcwq
= get_gcwq(smp_processor_id());
3499 struct worker_pool
*pool
;
3500 struct worker
*worker
;
3501 struct hlist_node
*pos
;
3504 BUG_ON(gcwq
->cpu
!= smp_processor_id());
3506 gcwq_claim_assoc_and_lock(gcwq
);
3509 * We've claimed all manager positions. Make all workers unbound
3510 * and set DISASSOCIATED. Before this, all workers except for the
3511 * ones which are still executing works from before the last CPU
3512 * down must be on the cpu. After this, they may become diasporas.
3514 for_each_worker_pool(pool
, gcwq
)
3515 list_for_each_entry(worker
, &pool
->idle_list
, entry
)
3516 worker
->flags
|= WORKER_UNBOUND
;
3518 for_each_busy_worker(worker
, i
, pos
, gcwq
)
3519 worker
->flags
|= WORKER_UNBOUND
;
3521 gcwq
->flags
|= GCWQ_DISASSOCIATED
;
3523 gcwq_release_assoc_and_unlock(gcwq
);
3526 * Call schedule() so that we cross rq->lock and thus can guarantee
3527 * sched callbacks see the %WORKER_UNBOUND flag. This is necessary
3528 * as scheduler callbacks may be invoked from other cpus.
3533 * Sched callbacks are disabled now. Zap nr_running. After this,
3534 * nr_running stays zero and need_more_worker() and keep_working()
3535 * are always true as long as the worklist is not empty. @gcwq now
3536 * behaves as unbound (in terms of concurrency management) gcwq
3537 * which is served by workers tied to the CPU.
3539 * On return from this function, the current worker would trigger
3540 * unbound chain execution of pending work items if other workers
3543 for_each_worker_pool(pool
, gcwq
)
3544 atomic_set(get_pool_nr_running(pool
), 0);
3548 * Workqueues should be brought up before normal priority CPU notifiers.
3549 * This will be registered high priority CPU notifier.
3551 static int __cpuinit
workqueue_cpu_up_callback(struct notifier_block
*nfb
,
3552 unsigned long action
,
3555 unsigned int cpu
= (unsigned long)hcpu
;
3556 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3557 struct worker_pool
*pool
;
3559 switch (action
& ~CPU_TASKS_FROZEN
) {
3560 case CPU_UP_PREPARE
:
3561 for_each_worker_pool(pool
, gcwq
) {
3562 struct worker
*worker
;
3564 if (pool
->nr_workers
)
3567 worker
= create_worker(pool
);
3571 spin_lock_irq(&gcwq
->lock
);
3572 start_worker(worker
);
3573 spin_unlock_irq(&gcwq
->lock
);
3577 case CPU_DOWN_FAILED
:
3579 gcwq_claim_assoc_and_lock(gcwq
);
3580 gcwq
->flags
&= ~GCWQ_DISASSOCIATED
;
3581 rebind_workers(gcwq
);
3582 gcwq_release_assoc_and_unlock(gcwq
);
3589 * Workqueues should be brought down after normal priority CPU notifiers.
3590 * This will be registered as low priority CPU notifier.
3592 static int __cpuinit
workqueue_cpu_down_callback(struct notifier_block
*nfb
,
3593 unsigned long action
,
3596 unsigned int cpu
= (unsigned long)hcpu
;
3597 struct work_struct unbind_work
;
3599 switch (action
& ~CPU_TASKS_FROZEN
) {
3600 case CPU_DOWN_PREPARE
:
3601 /* unbinding should happen on the local CPU */
3602 INIT_WORK_ONSTACK(&unbind_work
, gcwq_unbind_fn
);
3603 queue_work_on(cpu
, system_highpri_wq
, &unbind_work
);
3604 flush_work(&unbind_work
);
3612 struct work_for_cpu
{
3613 struct completion completion
;
3619 static int do_work_for_cpu(void *_wfc
)
3621 struct work_for_cpu
*wfc
= _wfc
;
3622 wfc
->ret
= wfc
->fn(wfc
->arg
);
3623 complete(&wfc
->completion
);
3628 * work_on_cpu - run a function in user context on a particular cpu
3629 * @cpu: the cpu to run on
3630 * @fn: the function to run
3631 * @arg: the function arg
3633 * This will return the value @fn returns.
3634 * It is up to the caller to ensure that the cpu doesn't go offline.
3635 * The caller must not hold any locks which would prevent @fn from completing.
3637 long work_on_cpu(unsigned int cpu
, long (*fn
)(void *), void *arg
)
3639 struct task_struct
*sub_thread
;
3640 struct work_for_cpu wfc
= {
3641 .completion
= COMPLETION_INITIALIZER_ONSTACK(wfc
.completion
),
3646 sub_thread
= kthread_create(do_work_for_cpu
, &wfc
, "work_for_cpu");
3647 if (IS_ERR(sub_thread
))
3648 return PTR_ERR(sub_thread
);
3649 kthread_bind(sub_thread
, cpu
);
3650 wake_up_process(sub_thread
);
3651 wait_for_completion(&wfc
.completion
);
3654 EXPORT_SYMBOL_GPL(work_on_cpu
);
3655 #endif /* CONFIG_SMP */
3657 #ifdef CONFIG_FREEZER
3660 * freeze_workqueues_begin - begin freezing workqueues
3662 * Start freezing workqueues. After this function returns, all freezable
3663 * workqueues will queue new works to their frozen_works list instead of
3667 * Grabs and releases workqueue_lock and gcwq->lock's.
3669 void freeze_workqueues_begin(void)
3673 spin_lock(&workqueue_lock
);
3675 BUG_ON(workqueue_freezing
);
3676 workqueue_freezing
= true;
3678 for_each_gcwq_cpu(cpu
) {
3679 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3680 struct workqueue_struct
*wq
;
3682 spin_lock_irq(&gcwq
->lock
);
3684 BUG_ON(gcwq
->flags
& GCWQ_FREEZING
);
3685 gcwq
->flags
|= GCWQ_FREEZING
;
3687 list_for_each_entry(wq
, &workqueues
, list
) {
3688 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3690 if (cwq
&& wq
->flags
& WQ_FREEZABLE
)
3691 cwq
->max_active
= 0;
3694 spin_unlock_irq(&gcwq
->lock
);
3697 spin_unlock(&workqueue_lock
);
3701 * freeze_workqueues_busy - are freezable workqueues still busy?
3703 * Check whether freezing is complete. This function must be called
3704 * between freeze_workqueues_begin() and thaw_workqueues().
3707 * Grabs and releases workqueue_lock.
3710 * %true if some freezable workqueues are still busy. %false if freezing
3713 bool freeze_workqueues_busy(void)
3718 spin_lock(&workqueue_lock
);
3720 BUG_ON(!workqueue_freezing
);
3722 for_each_gcwq_cpu(cpu
) {
3723 struct workqueue_struct
*wq
;
3725 * nr_active is monotonically decreasing. It's safe
3726 * to peek without lock.
3728 list_for_each_entry(wq
, &workqueues
, list
) {
3729 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3731 if (!cwq
|| !(wq
->flags
& WQ_FREEZABLE
))
3734 BUG_ON(cwq
->nr_active
< 0);
3735 if (cwq
->nr_active
) {
3742 spin_unlock(&workqueue_lock
);
3747 * thaw_workqueues - thaw workqueues
3749 * Thaw workqueues. Normal queueing is restored and all collected
3750 * frozen works are transferred to their respective gcwq worklists.
3753 * Grabs and releases workqueue_lock and gcwq->lock's.
3755 void thaw_workqueues(void)
3759 spin_lock(&workqueue_lock
);
3761 if (!workqueue_freezing
)
3764 for_each_gcwq_cpu(cpu
) {
3765 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3766 struct worker_pool
*pool
;
3767 struct workqueue_struct
*wq
;
3769 spin_lock_irq(&gcwq
->lock
);
3771 BUG_ON(!(gcwq
->flags
& GCWQ_FREEZING
));
3772 gcwq
->flags
&= ~GCWQ_FREEZING
;
3774 list_for_each_entry(wq
, &workqueues
, list
) {
3775 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3777 if (!cwq
|| !(wq
->flags
& WQ_FREEZABLE
))
3780 /* restore max_active and repopulate worklist */
3781 cwq
->max_active
= wq
->saved_max_active
;
3783 while (!list_empty(&cwq
->delayed_works
) &&
3784 cwq
->nr_active
< cwq
->max_active
)
3785 cwq_activate_first_delayed(cwq
);
3788 for_each_worker_pool(pool
, gcwq
)
3789 wake_up_worker(pool
);
3791 spin_unlock_irq(&gcwq
->lock
);
3794 workqueue_freezing
= false;
3796 spin_unlock(&workqueue_lock
);
3798 #endif /* CONFIG_FREEZER */
3800 static int __init
init_workqueues(void)
3805 /* make sure we have enough bits for OFFQ CPU number */
3806 BUILD_BUG_ON((1LU << (BITS_PER_LONG
- WORK_OFFQ_CPU_SHIFT
)) <
3809 cpu_notifier(workqueue_cpu_up_callback
, CPU_PRI_WORKQUEUE_UP
);
3810 hotcpu_notifier(workqueue_cpu_down_callback
, CPU_PRI_WORKQUEUE_DOWN
);
3812 /* initialize gcwqs */
3813 for_each_gcwq_cpu(cpu
) {
3814 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3815 struct worker_pool
*pool
;
3817 spin_lock_init(&gcwq
->lock
);
3819 gcwq
->flags
|= GCWQ_DISASSOCIATED
;
3821 for (i
= 0; i
< BUSY_WORKER_HASH_SIZE
; i
++)
3822 INIT_HLIST_HEAD(&gcwq
->busy_hash
[i
]);
3824 for_each_worker_pool(pool
, gcwq
) {
3826 INIT_LIST_HEAD(&pool
->worklist
);
3827 INIT_LIST_HEAD(&pool
->idle_list
);
3829 init_timer_deferrable(&pool
->idle_timer
);
3830 pool
->idle_timer
.function
= idle_worker_timeout
;
3831 pool
->idle_timer
.data
= (unsigned long)pool
;
3833 setup_timer(&pool
->mayday_timer
, gcwq_mayday_timeout
,
3834 (unsigned long)pool
);
3836 mutex_init(&pool
->assoc_mutex
);
3837 ida_init(&pool
->worker_ida
);
3841 /* create the initial worker */
3842 for_each_online_gcwq_cpu(cpu
) {
3843 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3844 struct worker_pool
*pool
;
3846 if (cpu
!= WORK_CPU_UNBOUND
)
3847 gcwq
->flags
&= ~GCWQ_DISASSOCIATED
;
3849 for_each_worker_pool(pool
, gcwq
) {
3850 struct worker
*worker
;
3852 worker
= create_worker(pool
);
3854 spin_lock_irq(&gcwq
->lock
);
3855 start_worker(worker
);
3856 spin_unlock_irq(&gcwq
->lock
);
3860 system_wq
= alloc_workqueue("events", 0, 0);
3861 system_highpri_wq
= alloc_workqueue("events_highpri", WQ_HIGHPRI
, 0);
3862 system_long_wq
= alloc_workqueue("events_long", 0, 0);
3863 system_unbound_wq
= alloc_workqueue("events_unbound", WQ_UNBOUND
,
3864 WQ_UNBOUND_MAX_ACTIVE
);
3865 system_freezable_wq
= alloc_workqueue("events_freezable",
3867 BUG_ON(!system_wq
|| !system_highpri_wq
|| !system_long_wq
||
3868 !system_unbound_wq
|| !system_freezable_wq
);
3871 early_initcall(init_workqueues
);