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"
48 /* global_cwq flags */
49 GCWQ_MANAGE_WORKERS
= 1 << 0, /* need to manage workers */
50 GCWQ_MANAGING_WORKERS
= 1 << 1, /* managing workers */
51 GCWQ_DISASSOCIATED
= 1 << 2, /* cpu can't serve workers */
52 GCWQ_FREEZING
= 1 << 3, /* freeze in progress */
53 GCWQ_HIGHPRI_PENDING
= 1 << 4, /* highpri works on queue */
56 WORKER_STARTED
= 1 << 0, /* started */
57 WORKER_DIE
= 1 << 1, /* die die die */
58 WORKER_IDLE
= 1 << 2, /* is idle */
59 WORKER_PREP
= 1 << 3, /* preparing to run works */
60 WORKER_ROGUE
= 1 << 4, /* not bound to any cpu */
61 WORKER_REBIND
= 1 << 5, /* mom is home, come back */
62 WORKER_CPU_INTENSIVE
= 1 << 6, /* cpu intensive */
63 WORKER_UNBOUND
= 1 << 7, /* worker is unbound */
65 WORKER_NOT_RUNNING
= WORKER_PREP
| WORKER_ROGUE
| WORKER_REBIND
|
66 WORKER_CPU_INTENSIVE
| WORKER_UNBOUND
,
68 /* gcwq->trustee_state */
69 TRUSTEE_START
= 0, /* start */
70 TRUSTEE_IN_CHARGE
= 1, /* trustee in charge of gcwq */
71 TRUSTEE_BUTCHER
= 2, /* butcher workers */
72 TRUSTEE_RELEASE
= 3, /* release workers */
73 TRUSTEE_DONE
= 4, /* trustee is done */
75 BUSY_WORKER_HASH_ORDER
= 6, /* 64 pointers */
76 BUSY_WORKER_HASH_SIZE
= 1 << BUSY_WORKER_HASH_ORDER
,
77 BUSY_WORKER_HASH_MASK
= BUSY_WORKER_HASH_SIZE
- 1,
79 MAX_IDLE_WORKERS_RATIO
= 4, /* 1/4 of busy can be idle */
80 IDLE_WORKER_TIMEOUT
= 300 * HZ
, /* keep idle ones for 5 mins */
82 MAYDAY_INITIAL_TIMEOUT
= HZ
/ 100 >= 2 ? HZ
/ 100 : 2,
83 /* call for help after 10ms
85 MAYDAY_INTERVAL
= HZ
/ 10, /* and then every 100ms */
86 CREATE_COOLDOWN
= HZ
, /* time to breath after fail */
87 TRUSTEE_COOLDOWN
= HZ
/ 10, /* for trustee draining */
90 * Rescue workers are used only on emergencies and shared by
93 RESCUER_NICE_LEVEL
= -20,
97 * Structure fields follow one of the following exclusion rules.
99 * I: Modifiable by initialization/destruction paths and read-only for
102 * P: Preemption protected. Disabling preemption is enough and should
103 * only be modified and accessed from the local cpu.
105 * L: gcwq->lock protected. Access with gcwq->lock held.
107 * X: During normal operation, modification requires gcwq->lock and
108 * should be done only from local cpu. Either disabling preemption
109 * on local cpu or grabbing gcwq->lock is enough for read access.
110 * If GCWQ_DISASSOCIATED is set, it's identical to L.
112 * F: wq->flush_mutex protected.
114 * W: workqueue_lock protected.
121 * The poor guys doing the actual heavy lifting. All on-duty workers
122 * are either serving the manager role, on idle list or on busy hash.
125 /* on idle list while idle, on busy hash table while busy */
127 struct list_head entry
; /* L: while idle */
128 struct hlist_node hentry
; /* L: while busy */
131 struct work_struct
*current_work
; /* L: work being processed */
132 struct cpu_workqueue_struct
*current_cwq
; /* L: current_work's cwq */
133 struct list_head scheduled
; /* L: scheduled works */
134 struct task_struct
*task
; /* I: worker task */
135 struct worker_pool
*pool
; /* I: the associated pool */
136 /* 64 bytes boundary on 64bit, 32 on 32bit */
137 unsigned long last_active
; /* L: last active timestamp */
138 unsigned int flags
; /* X: flags */
139 int id
; /* I: worker id */
140 struct work_struct rebind_work
; /* L: rebind worker to cpu */
144 struct global_cwq
*gcwq
; /* I: the owning gcwq */
146 struct list_head worklist
; /* L: list of pending works */
147 int nr_workers
; /* L: total number of workers */
148 int nr_idle
; /* L: currently idle ones */
150 struct list_head idle_list
; /* X: list of idle workers */
151 struct timer_list idle_timer
; /* L: worker idle timeout */
152 struct timer_list mayday_timer
; /* L: SOS timer for workers */
154 struct ida worker_ida
; /* L: for worker IDs */
155 struct worker
*first_idle
; /* L: first idle worker */
159 * Global per-cpu workqueue. There's one and only one for each cpu
160 * and all works are queued and processed here regardless of their
164 spinlock_t lock
; /* the gcwq lock */
165 unsigned int cpu
; /* I: the associated cpu */
166 unsigned int flags
; /* L: GCWQ_* flags */
168 /* workers are chained either in busy_hash or pool idle_list */
169 struct hlist_head busy_hash
[BUSY_WORKER_HASH_SIZE
];
170 /* L: hash of busy workers */
172 struct worker_pool pool
; /* the worker pools */
174 struct task_struct
*trustee
; /* L: for gcwq shutdown */
175 unsigned int trustee_state
; /* L: trustee state */
176 wait_queue_head_t trustee_wait
; /* trustee wait */
177 } ____cacheline_aligned_in_smp
;
180 * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of
181 * work_struct->data are used for flags and thus cwqs need to be
182 * aligned at two's power of the number of flag bits.
184 struct cpu_workqueue_struct
{
185 struct worker_pool
*pool
; /* I: the associated pool */
186 struct workqueue_struct
*wq
; /* I: the owning workqueue */
187 int work_color
; /* L: current color */
188 int flush_color
; /* L: flushing color */
189 int nr_in_flight
[WORK_NR_COLORS
];
190 /* L: nr of in_flight works */
191 int nr_active
; /* L: nr of active works */
192 int max_active
; /* L: max active works */
193 struct list_head delayed_works
; /* L: delayed works */
197 * Structure used to wait for workqueue flush.
200 struct list_head list
; /* F: list of flushers */
201 int flush_color
; /* F: flush color waiting for */
202 struct completion done
; /* flush completion */
206 * All cpumasks are assumed to be always set on UP and thus can't be
207 * used to determine whether there's something to be done.
210 typedef cpumask_var_t mayday_mask_t
;
211 #define mayday_test_and_set_cpu(cpu, mask) \
212 cpumask_test_and_set_cpu((cpu), (mask))
213 #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask))
214 #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask))
215 #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp))
216 #define free_mayday_mask(mask) free_cpumask_var((mask))
218 typedef unsigned long mayday_mask_t
;
219 #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask))
220 #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask))
221 #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask))
222 #define alloc_mayday_mask(maskp, gfp) true
223 #define free_mayday_mask(mask) do { } while (0)
227 * The externally visible workqueue abstraction is an array of
228 * per-CPU workqueues:
230 struct workqueue_struct
{
231 unsigned int flags
; /* W: WQ_* flags */
233 struct cpu_workqueue_struct __percpu
*pcpu
;
234 struct cpu_workqueue_struct
*single
;
236 } cpu_wq
; /* I: cwq's */
237 struct list_head list
; /* W: list of all workqueues */
239 struct mutex flush_mutex
; /* protects wq flushing */
240 int work_color
; /* F: current work color */
241 int flush_color
; /* F: current flush color */
242 atomic_t nr_cwqs_to_flush
; /* flush in progress */
243 struct wq_flusher
*first_flusher
; /* F: first flusher */
244 struct list_head flusher_queue
; /* F: flush waiters */
245 struct list_head flusher_overflow
; /* F: flush overflow list */
247 mayday_mask_t mayday_mask
; /* cpus requesting rescue */
248 struct worker
*rescuer
; /* I: rescue worker */
250 int nr_drainers
; /* W: drain in progress */
251 int saved_max_active
; /* W: saved cwq max_active */
252 #ifdef CONFIG_LOCKDEP
253 struct lockdep_map lockdep_map
;
255 char name
[]; /* I: workqueue name */
258 struct workqueue_struct
*system_wq __read_mostly
;
259 struct workqueue_struct
*system_long_wq __read_mostly
;
260 struct workqueue_struct
*system_nrt_wq __read_mostly
;
261 struct workqueue_struct
*system_unbound_wq __read_mostly
;
262 struct workqueue_struct
*system_freezable_wq __read_mostly
;
263 struct workqueue_struct
*system_nrt_freezable_wq __read_mostly
;
264 EXPORT_SYMBOL_GPL(system_wq
);
265 EXPORT_SYMBOL_GPL(system_long_wq
);
266 EXPORT_SYMBOL_GPL(system_nrt_wq
);
267 EXPORT_SYMBOL_GPL(system_unbound_wq
);
268 EXPORT_SYMBOL_GPL(system_freezable_wq
);
269 EXPORT_SYMBOL_GPL(system_nrt_freezable_wq
);
271 #define CREATE_TRACE_POINTS
272 #include <trace/events/workqueue.h>
274 #define for_each_busy_worker(worker, i, pos, gcwq) \
275 for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \
276 hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry)
278 static inline int __next_gcwq_cpu(int cpu
, const struct cpumask
*mask
,
281 if (cpu
< nr_cpu_ids
) {
283 cpu
= cpumask_next(cpu
, mask
);
284 if (cpu
< nr_cpu_ids
)
288 return WORK_CPU_UNBOUND
;
290 return WORK_CPU_NONE
;
293 static inline int __next_wq_cpu(int cpu
, const struct cpumask
*mask
,
294 struct workqueue_struct
*wq
)
296 return __next_gcwq_cpu(cpu
, mask
, !(wq
->flags
& WQ_UNBOUND
) ? 1 : 2);
302 * An extra gcwq is defined for an invalid cpu number
303 * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any
304 * specific CPU. The following iterators are similar to
305 * for_each_*_cpu() iterators but also considers the unbound gcwq.
307 * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND
308 * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND
309 * for_each_cwq_cpu() : possible CPUs for bound workqueues,
310 * WORK_CPU_UNBOUND for unbound workqueues
312 #define for_each_gcwq_cpu(cpu) \
313 for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \
314 (cpu) < WORK_CPU_NONE; \
315 (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3))
317 #define for_each_online_gcwq_cpu(cpu) \
318 for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \
319 (cpu) < WORK_CPU_NONE; \
320 (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3))
322 #define for_each_cwq_cpu(cpu, wq) \
323 for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \
324 (cpu) < WORK_CPU_NONE; \
325 (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq)))
327 #ifdef CONFIG_DEBUG_OBJECTS_WORK
329 static struct debug_obj_descr work_debug_descr
;
331 static void *work_debug_hint(void *addr
)
333 return ((struct work_struct
*) addr
)->func
;
337 * fixup_init is called when:
338 * - an active object is initialized
340 static int work_fixup_init(void *addr
, enum debug_obj_state state
)
342 struct work_struct
*work
= addr
;
345 case ODEBUG_STATE_ACTIVE
:
346 cancel_work_sync(work
);
347 debug_object_init(work
, &work_debug_descr
);
355 * fixup_activate is called when:
356 * - an active object is activated
357 * - an unknown object is activated (might be a statically initialized object)
359 static int work_fixup_activate(void *addr
, enum debug_obj_state state
)
361 struct work_struct
*work
= addr
;
365 case ODEBUG_STATE_NOTAVAILABLE
:
367 * This is not really a fixup. The work struct was
368 * statically initialized. We just make sure that it
369 * is tracked in the object tracker.
371 if (test_bit(WORK_STRUCT_STATIC_BIT
, work_data_bits(work
))) {
372 debug_object_init(work
, &work_debug_descr
);
373 debug_object_activate(work
, &work_debug_descr
);
379 case ODEBUG_STATE_ACTIVE
:
388 * fixup_free is called when:
389 * - an active object is freed
391 static int work_fixup_free(void *addr
, enum debug_obj_state state
)
393 struct work_struct
*work
= addr
;
396 case ODEBUG_STATE_ACTIVE
:
397 cancel_work_sync(work
);
398 debug_object_free(work
, &work_debug_descr
);
405 static struct debug_obj_descr work_debug_descr
= {
406 .name
= "work_struct",
407 .debug_hint
= work_debug_hint
,
408 .fixup_init
= work_fixup_init
,
409 .fixup_activate
= work_fixup_activate
,
410 .fixup_free
= work_fixup_free
,
413 static inline void debug_work_activate(struct work_struct
*work
)
415 debug_object_activate(work
, &work_debug_descr
);
418 static inline void debug_work_deactivate(struct work_struct
*work
)
420 debug_object_deactivate(work
, &work_debug_descr
);
423 void __init_work(struct work_struct
*work
, int onstack
)
426 debug_object_init_on_stack(work
, &work_debug_descr
);
428 debug_object_init(work
, &work_debug_descr
);
430 EXPORT_SYMBOL_GPL(__init_work
);
432 void destroy_work_on_stack(struct work_struct
*work
)
434 debug_object_free(work
, &work_debug_descr
);
436 EXPORT_SYMBOL_GPL(destroy_work_on_stack
);
439 static inline void debug_work_activate(struct work_struct
*work
) { }
440 static inline void debug_work_deactivate(struct work_struct
*work
) { }
443 /* Serializes the accesses to the list of workqueues. */
444 static DEFINE_SPINLOCK(workqueue_lock
);
445 static LIST_HEAD(workqueues
);
446 static bool workqueue_freezing
; /* W: have wqs started freezing? */
449 * The almighty global cpu workqueues. nr_running is the only field
450 * which is expected to be used frequently by other cpus via
451 * try_to_wake_up(). Put it in a separate cacheline.
453 static DEFINE_PER_CPU(struct global_cwq
, global_cwq
);
454 static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t
, gcwq_nr_running
);
457 * Global cpu workqueue and nr_running counter for unbound gcwq. The
458 * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its
459 * workers have WORKER_UNBOUND set.
461 static struct global_cwq unbound_global_cwq
;
462 static atomic_t unbound_gcwq_nr_running
= ATOMIC_INIT(0); /* always 0 */
464 static int worker_thread(void *__worker
);
466 static struct global_cwq
*get_gcwq(unsigned int cpu
)
468 if (cpu
!= WORK_CPU_UNBOUND
)
469 return &per_cpu(global_cwq
, cpu
);
471 return &unbound_global_cwq
;
474 static atomic_t
*get_pool_nr_running(struct worker_pool
*pool
)
476 int cpu
= pool
->gcwq
->cpu
;
478 if (cpu
!= WORK_CPU_UNBOUND
)
479 return &per_cpu(gcwq_nr_running
, cpu
);
481 return &unbound_gcwq_nr_running
;
484 static struct cpu_workqueue_struct
*get_cwq(unsigned int cpu
,
485 struct workqueue_struct
*wq
)
487 if (!(wq
->flags
& WQ_UNBOUND
)) {
488 if (likely(cpu
< nr_cpu_ids
))
489 return per_cpu_ptr(wq
->cpu_wq
.pcpu
, cpu
);
490 } else if (likely(cpu
== WORK_CPU_UNBOUND
))
491 return wq
->cpu_wq
.single
;
495 static unsigned int work_color_to_flags(int color
)
497 return color
<< WORK_STRUCT_COLOR_SHIFT
;
500 static int get_work_color(struct work_struct
*work
)
502 return (*work_data_bits(work
) >> WORK_STRUCT_COLOR_SHIFT
) &
503 ((1 << WORK_STRUCT_COLOR_BITS
) - 1);
506 static int work_next_color(int color
)
508 return (color
+ 1) % WORK_NR_COLORS
;
512 * A work's data points to the cwq with WORK_STRUCT_CWQ set while the
513 * work is on queue. Once execution starts, WORK_STRUCT_CWQ is
514 * cleared and the work data contains the cpu number it was last on.
516 * set_work_{cwq|cpu}() and clear_work_data() can be used to set the
517 * cwq, cpu or clear work->data. These functions should only be
518 * called while the work is owned - ie. while the PENDING bit is set.
520 * get_work_[g]cwq() can be used to obtain the gcwq or cwq
521 * corresponding to a work. gcwq is available once the work has been
522 * queued anywhere after initialization. cwq is available only from
523 * queueing until execution starts.
525 static inline void set_work_data(struct work_struct
*work
, unsigned long data
,
528 BUG_ON(!work_pending(work
));
529 atomic_long_set(&work
->data
, data
| flags
| work_static(work
));
532 static void set_work_cwq(struct work_struct
*work
,
533 struct cpu_workqueue_struct
*cwq
,
534 unsigned long extra_flags
)
536 set_work_data(work
, (unsigned long)cwq
,
537 WORK_STRUCT_PENDING
| WORK_STRUCT_CWQ
| extra_flags
);
540 static void set_work_cpu(struct work_struct
*work
, unsigned int cpu
)
542 set_work_data(work
, cpu
<< WORK_STRUCT_FLAG_BITS
, WORK_STRUCT_PENDING
);
545 static void clear_work_data(struct work_struct
*work
)
547 set_work_data(work
, WORK_STRUCT_NO_CPU
, 0);
550 static struct cpu_workqueue_struct
*get_work_cwq(struct work_struct
*work
)
552 unsigned long data
= atomic_long_read(&work
->data
);
554 if (data
& WORK_STRUCT_CWQ
)
555 return (void *)(data
& WORK_STRUCT_WQ_DATA_MASK
);
560 static struct global_cwq
*get_work_gcwq(struct work_struct
*work
)
562 unsigned long data
= atomic_long_read(&work
->data
);
565 if (data
& WORK_STRUCT_CWQ
)
566 return ((struct cpu_workqueue_struct
*)
567 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
->gcwq
;
569 cpu
= data
>> WORK_STRUCT_FLAG_BITS
;
570 if (cpu
== WORK_CPU_NONE
)
573 BUG_ON(cpu
>= nr_cpu_ids
&& cpu
!= WORK_CPU_UNBOUND
);
574 return get_gcwq(cpu
);
578 * Policy functions. These define the policies on how the global
579 * worker pool is managed. Unless noted otherwise, these functions
580 * assume that they're being called with gcwq->lock held.
583 static bool __need_more_worker(struct worker_pool
*pool
)
585 return !atomic_read(get_pool_nr_running(pool
)) ||
586 pool
->gcwq
->flags
& GCWQ_HIGHPRI_PENDING
;
590 * Need to wake up a worker? Called from anything but currently
593 * Note that, because unbound workers never contribute to nr_running, this
594 * function will always return %true for unbound gcwq as long as the
595 * worklist isn't empty.
597 static bool need_more_worker(struct worker_pool
*pool
)
599 return !list_empty(&pool
->worklist
) && __need_more_worker(pool
);
602 /* Can I start working? Called from busy but !running workers. */
603 static bool may_start_working(struct worker_pool
*pool
)
605 return pool
->nr_idle
;
608 /* Do I need to keep working? Called from currently running workers. */
609 static bool keep_working(struct worker_pool
*pool
)
611 atomic_t
*nr_running
= get_pool_nr_running(pool
);
613 return !list_empty(&pool
->worklist
) &&
614 (atomic_read(nr_running
) <= 1 ||
615 pool
->gcwq
->flags
& GCWQ_HIGHPRI_PENDING
);
618 /* Do we need a new worker? Called from manager. */
619 static bool need_to_create_worker(struct worker_pool
*pool
)
621 return need_more_worker(pool
) && !may_start_working(pool
);
624 /* Do I need to be the manager? */
625 static bool need_to_manage_workers(struct worker_pool
*pool
)
627 return need_to_create_worker(pool
) ||
628 pool
->gcwq
->flags
& GCWQ_MANAGE_WORKERS
;
631 /* Do we have too many workers and should some go away? */
632 static bool too_many_workers(struct worker_pool
*pool
)
634 bool managing
= pool
->gcwq
->flags
& GCWQ_MANAGING_WORKERS
;
635 int nr_idle
= pool
->nr_idle
+ managing
; /* manager is considered idle */
636 int nr_busy
= pool
->nr_workers
- nr_idle
;
638 return nr_idle
> 2 && (nr_idle
- 2) * MAX_IDLE_WORKERS_RATIO
>= nr_busy
;
645 /* Return the first worker. Safe with preemption disabled */
646 static struct worker
*first_worker(struct worker_pool
*pool
)
648 if (unlikely(list_empty(&pool
->idle_list
)))
651 return list_first_entry(&pool
->idle_list
, struct worker
, entry
);
655 * wake_up_worker - wake up an idle worker
656 * @pool: worker pool to wake worker from
658 * Wake up the first idle worker of @pool.
661 * spin_lock_irq(gcwq->lock).
663 static void wake_up_worker(struct worker_pool
*pool
)
665 struct worker
*worker
= first_worker(pool
);
668 wake_up_process(worker
->task
);
672 * wq_worker_waking_up - a worker is waking up
673 * @task: task waking up
674 * @cpu: CPU @task is waking up to
676 * This function is called during try_to_wake_up() when a worker is
680 * spin_lock_irq(rq->lock)
682 void wq_worker_waking_up(struct task_struct
*task
, unsigned int cpu
)
684 struct worker
*worker
= kthread_data(task
);
686 if (!(worker
->flags
& WORKER_NOT_RUNNING
))
687 atomic_inc(get_pool_nr_running(worker
->pool
));
691 * wq_worker_sleeping - a worker is going to sleep
692 * @task: task going to sleep
693 * @cpu: CPU in question, must be the current CPU number
695 * This function is called during schedule() when a busy worker is
696 * going to sleep. Worker on the same cpu can be woken up by
697 * returning pointer to its task.
700 * spin_lock_irq(rq->lock)
703 * Worker task on @cpu to wake up, %NULL if none.
705 struct task_struct
*wq_worker_sleeping(struct task_struct
*task
,
708 struct worker
*worker
= kthread_data(task
), *to_wakeup
= NULL
;
709 struct worker_pool
*pool
= worker
->pool
;
710 atomic_t
*nr_running
= get_pool_nr_running(pool
);
712 if (worker
->flags
& WORKER_NOT_RUNNING
)
715 /* this can only happen on the local cpu */
716 BUG_ON(cpu
!= raw_smp_processor_id());
719 * The counterpart of the following dec_and_test, implied mb,
720 * worklist not empty test sequence is in insert_work().
721 * Please read comment there.
723 * NOT_RUNNING is clear. This means that trustee is not in
724 * charge and we're running on the local cpu w/ rq lock held
725 * and preemption disabled, which in turn means that none else
726 * could be manipulating idle_list, so dereferencing idle_list
727 * without gcwq lock is safe.
729 if (atomic_dec_and_test(nr_running
) && !list_empty(&pool
->worklist
))
730 to_wakeup
= first_worker(pool
);
731 return to_wakeup
? to_wakeup
->task
: NULL
;
735 * worker_set_flags - set worker flags and adjust nr_running accordingly
737 * @flags: flags to set
738 * @wakeup: wakeup an idle worker if necessary
740 * Set @flags in @worker->flags and adjust nr_running accordingly. If
741 * nr_running becomes zero and @wakeup is %true, an idle worker is
745 * spin_lock_irq(gcwq->lock)
747 static inline void worker_set_flags(struct worker
*worker
, unsigned int flags
,
750 struct worker_pool
*pool
= worker
->pool
;
752 WARN_ON_ONCE(worker
->task
!= current
);
755 * If transitioning into NOT_RUNNING, adjust nr_running and
756 * wake up an idle worker as necessary if requested by
759 if ((flags
& WORKER_NOT_RUNNING
) &&
760 !(worker
->flags
& WORKER_NOT_RUNNING
)) {
761 atomic_t
*nr_running
= get_pool_nr_running(pool
);
764 if (atomic_dec_and_test(nr_running
) &&
765 !list_empty(&pool
->worklist
))
766 wake_up_worker(pool
);
768 atomic_dec(nr_running
);
771 worker
->flags
|= flags
;
775 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
777 * @flags: flags to clear
779 * Clear @flags in @worker->flags and adjust nr_running accordingly.
782 * spin_lock_irq(gcwq->lock)
784 static inline void worker_clr_flags(struct worker
*worker
, unsigned int flags
)
786 struct worker_pool
*pool
= worker
->pool
;
787 unsigned int oflags
= worker
->flags
;
789 WARN_ON_ONCE(worker
->task
!= current
);
791 worker
->flags
&= ~flags
;
794 * If transitioning out of NOT_RUNNING, increment nr_running. Note
795 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
796 * of multiple flags, not a single flag.
798 if ((flags
& WORKER_NOT_RUNNING
) && (oflags
& WORKER_NOT_RUNNING
))
799 if (!(worker
->flags
& WORKER_NOT_RUNNING
))
800 atomic_inc(get_pool_nr_running(pool
));
804 * busy_worker_head - return the busy hash head for a work
805 * @gcwq: gcwq of interest
806 * @work: work to be hashed
808 * Return hash head of @gcwq for @work.
811 * spin_lock_irq(gcwq->lock).
814 * Pointer to the hash head.
816 static struct hlist_head
*busy_worker_head(struct global_cwq
*gcwq
,
817 struct work_struct
*work
)
819 const int base_shift
= ilog2(sizeof(struct work_struct
));
820 unsigned long v
= (unsigned long)work
;
822 /* simple shift and fold hash, do we need something better? */
824 v
+= v
>> BUSY_WORKER_HASH_ORDER
;
825 v
&= BUSY_WORKER_HASH_MASK
;
827 return &gcwq
->busy_hash
[v
];
831 * __find_worker_executing_work - find worker which is executing a work
832 * @gcwq: gcwq of interest
833 * @bwh: hash head as returned by busy_worker_head()
834 * @work: work to find worker for
836 * Find a worker which is executing @work on @gcwq. @bwh should be
837 * the hash head obtained by calling busy_worker_head() with the same
841 * spin_lock_irq(gcwq->lock).
844 * Pointer to worker which is executing @work if found, NULL
847 static struct worker
*__find_worker_executing_work(struct global_cwq
*gcwq
,
848 struct hlist_head
*bwh
,
849 struct work_struct
*work
)
851 struct worker
*worker
;
852 struct hlist_node
*tmp
;
854 hlist_for_each_entry(worker
, tmp
, bwh
, hentry
)
855 if (worker
->current_work
== work
)
861 * find_worker_executing_work - find worker which is executing a work
862 * @gcwq: gcwq of interest
863 * @work: work to find worker for
865 * Find a worker which is executing @work on @gcwq. This function is
866 * identical to __find_worker_executing_work() except that this
867 * function calculates @bwh itself.
870 * spin_lock_irq(gcwq->lock).
873 * Pointer to worker which is executing @work if found, NULL
876 static struct worker
*find_worker_executing_work(struct global_cwq
*gcwq
,
877 struct work_struct
*work
)
879 return __find_worker_executing_work(gcwq
, busy_worker_head(gcwq
, work
),
884 * pool_determine_ins_pos - find insertion position
885 * @pool: pool of interest
886 * @cwq: cwq a work is being queued for
888 * A work for @cwq is about to be queued on @pool, determine insertion
889 * position for the work. If @cwq is for HIGHPRI wq, the work is
890 * queued at the head of the queue but in FIFO order with respect to
891 * other HIGHPRI works; otherwise, at the end of the queue. This
892 * function also sets GCWQ_HIGHPRI_PENDING flag to hint @pool that
893 * there are HIGHPRI works pending.
896 * spin_lock_irq(gcwq->lock).
899 * Pointer to inserstion position.
901 static inline struct list_head
*pool_determine_ins_pos(struct worker_pool
*pool
,
902 struct cpu_workqueue_struct
*cwq
)
904 struct work_struct
*twork
;
906 if (likely(!(cwq
->wq
->flags
& WQ_HIGHPRI
)))
907 return &pool
->worklist
;
909 list_for_each_entry(twork
, &pool
->worklist
, entry
) {
910 struct cpu_workqueue_struct
*tcwq
= get_work_cwq(twork
);
912 if (!(tcwq
->wq
->flags
& WQ_HIGHPRI
))
916 pool
->gcwq
->flags
|= GCWQ_HIGHPRI_PENDING
;
917 return &twork
->entry
;
921 * insert_work - insert a work into gcwq
922 * @cwq: cwq @work belongs to
923 * @work: work to insert
924 * @head: insertion point
925 * @extra_flags: extra WORK_STRUCT_* flags to set
927 * Insert @work which belongs to @cwq into @gcwq after @head.
928 * @extra_flags is or'd to work_struct flags.
931 * spin_lock_irq(gcwq->lock).
933 static void insert_work(struct cpu_workqueue_struct
*cwq
,
934 struct work_struct
*work
, struct list_head
*head
,
935 unsigned int extra_flags
)
937 struct worker_pool
*pool
= cwq
->pool
;
939 /* we own @work, set data and link */
940 set_work_cwq(work
, cwq
, extra_flags
);
943 * Ensure that we get the right work->data if we see the
944 * result of list_add() below, see try_to_grab_pending().
948 list_add_tail(&work
->entry
, head
);
951 * Ensure either worker_sched_deactivated() sees the above
952 * list_add_tail() or we see zero nr_running to avoid workers
953 * lying around lazily while there are works to be processed.
957 if (__need_more_worker(pool
))
958 wake_up_worker(pool
);
962 * Test whether @work is being queued from another work executing on the
963 * same workqueue. This is rather expensive and should only be used from
966 static bool is_chained_work(struct workqueue_struct
*wq
)
971 for_each_gcwq_cpu(cpu
) {
972 struct global_cwq
*gcwq
= get_gcwq(cpu
);
973 struct worker
*worker
;
974 struct hlist_node
*pos
;
977 spin_lock_irqsave(&gcwq
->lock
, flags
);
978 for_each_busy_worker(worker
, i
, pos
, gcwq
) {
979 if (worker
->task
!= current
)
981 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
983 * I'm @worker, no locking necessary. See if @work
984 * is headed to the same workqueue.
986 return worker
->current_cwq
->wq
== wq
;
988 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
993 static void __queue_work(unsigned int cpu
, struct workqueue_struct
*wq
,
994 struct work_struct
*work
)
996 struct global_cwq
*gcwq
;
997 struct cpu_workqueue_struct
*cwq
;
998 struct list_head
*worklist
;
999 unsigned int work_flags
;
1000 unsigned long flags
;
1002 debug_work_activate(work
);
1004 /* if dying, only works from the same workqueue are allowed */
1005 if (unlikely(wq
->flags
& WQ_DRAINING
) &&
1006 WARN_ON_ONCE(!is_chained_work(wq
)))
1009 /* determine gcwq to use */
1010 if (!(wq
->flags
& WQ_UNBOUND
)) {
1011 struct global_cwq
*last_gcwq
;
1013 if (unlikely(cpu
== WORK_CPU_UNBOUND
))
1014 cpu
= raw_smp_processor_id();
1017 * It's multi cpu. If @wq is non-reentrant and @work
1018 * was previously on a different cpu, it might still
1019 * be running there, in which case the work needs to
1020 * be queued on that cpu to guarantee non-reentrance.
1022 gcwq
= get_gcwq(cpu
);
1023 if (wq
->flags
& WQ_NON_REENTRANT
&&
1024 (last_gcwq
= get_work_gcwq(work
)) && last_gcwq
!= gcwq
) {
1025 struct worker
*worker
;
1027 spin_lock_irqsave(&last_gcwq
->lock
, flags
);
1029 worker
= find_worker_executing_work(last_gcwq
, work
);
1031 if (worker
&& worker
->current_cwq
->wq
== wq
)
1034 /* meh... not running there, queue here */
1035 spin_unlock_irqrestore(&last_gcwq
->lock
, flags
);
1036 spin_lock_irqsave(&gcwq
->lock
, flags
);
1039 spin_lock_irqsave(&gcwq
->lock
, flags
);
1041 gcwq
= get_gcwq(WORK_CPU_UNBOUND
);
1042 spin_lock_irqsave(&gcwq
->lock
, flags
);
1045 /* gcwq determined, get cwq and queue */
1046 cwq
= get_cwq(gcwq
->cpu
, wq
);
1047 trace_workqueue_queue_work(cpu
, cwq
, work
);
1049 if (WARN_ON(!list_empty(&work
->entry
))) {
1050 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
1054 cwq
->nr_in_flight
[cwq
->work_color
]++;
1055 work_flags
= work_color_to_flags(cwq
->work_color
);
1057 if (likely(cwq
->nr_active
< cwq
->max_active
)) {
1058 trace_workqueue_activate_work(work
);
1060 worklist
= pool_determine_ins_pos(cwq
->pool
, cwq
);
1062 work_flags
|= WORK_STRUCT_DELAYED
;
1063 worklist
= &cwq
->delayed_works
;
1066 insert_work(cwq
, work
, worklist
, work_flags
);
1068 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
1072 * queue_work - queue work on a workqueue
1073 * @wq: workqueue to use
1074 * @work: work to queue
1076 * Returns 0 if @work was already on a queue, non-zero otherwise.
1078 * We queue the work to the CPU on which it was submitted, but if the CPU dies
1079 * it can be processed by another CPU.
1081 int queue_work(struct workqueue_struct
*wq
, struct work_struct
*work
)
1085 ret
= queue_work_on(get_cpu(), wq
, work
);
1090 EXPORT_SYMBOL_GPL(queue_work
);
1093 * queue_work_on - queue work on specific cpu
1094 * @cpu: CPU number to execute work on
1095 * @wq: workqueue to use
1096 * @work: work to queue
1098 * Returns 0 if @work was already on a queue, non-zero otherwise.
1100 * We queue the work to a specific CPU, the caller must ensure it
1104 queue_work_on(int cpu
, struct workqueue_struct
*wq
, struct work_struct
*work
)
1108 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1109 __queue_work(cpu
, wq
, work
);
1114 EXPORT_SYMBOL_GPL(queue_work_on
);
1116 static void delayed_work_timer_fn(unsigned long __data
)
1118 struct delayed_work
*dwork
= (struct delayed_work
*)__data
;
1119 struct cpu_workqueue_struct
*cwq
= get_work_cwq(&dwork
->work
);
1121 __queue_work(smp_processor_id(), cwq
->wq
, &dwork
->work
);
1125 * queue_delayed_work - queue work on a workqueue after delay
1126 * @wq: workqueue to use
1127 * @dwork: delayable work to queue
1128 * @delay: number of jiffies to wait before queueing
1130 * Returns 0 if @work was already on a queue, non-zero otherwise.
1132 int queue_delayed_work(struct workqueue_struct
*wq
,
1133 struct delayed_work
*dwork
, unsigned long delay
)
1136 return queue_work(wq
, &dwork
->work
);
1138 return queue_delayed_work_on(-1, wq
, dwork
, delay
);
1140 EXPORT_SYMBOL_GPL(queue_delayed_work
);
1143 * queue_delayed_work_on - queue work on specific CPU after delay
1144 * @cpu: CPU number to execute work on
1145 * @wq: workqueue to use
1146 * @dwork: work to queue
1147 * @delay: number of jiffies to wait before queueing
1149 * Returns 0 if @work was already on a queue, non-zero otherwise.
1151 int queue_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1152 struct delayed_work
*dwork
, unsigned long delay
)
1155 struct timer_list
*timer
= &dwork
->timer
;
1156 struct work_struct
*work
= &dwork
->work
;
1158 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1161 BUG_ON(timer_pending(timer
));
1162 BUG_ON(!list_empty(&work
->entry
));
1164 timer_stats_timer_set_start_info(&dwork
->timer
);
1167 * This stores cwq for the moment, for the timer_fn.
1168 * Note that the work's gcwq is preserved to allow
1169 * reentrance detection for delayed works.
1171 if (!(wq
->flags
& WQ_UNBOUND
)) {
1172 struct global_cwq
*gcwq
= get_work_gcwq(work
);
1174 if (gcwq
&& gcwq
->cpu
!= WORK_CPU_UNBOUND
)
1177 lcpu
= raw_smp_processor_id();
1179 lcpu
= WORK_CPU_UNBOUND
;
1181 set_work_cwq(work
, get_cwq(lcpu
, wq
), 0);
1183 timer
->expires
= jiffies
+ delay
;
1184 timer
->data
= (unsigned long)dwork
;
1185 timer
->function
= delayed_work_timer_fn
;
1187 if (unlikely(cpu
>= 0))
1188 add_timer_on(timer
, cpu
);
1195 EXPORT_SYMBOL_GPL(queue_delayed_work_on
);
1198 * worker_enter_idle - enter idle state
1199 * @worker: worker which is entering idle state
1201 * @worker is entering idle state. Update stats and idle timer if
1205 * spin_lock_irq(gcwq->lock).
1207 static void worker_enter_idle(struct worker
*worker
)
1209 struct worker_pool
*pool
= worker
->pool
;
1210 struct global_cwq
*gcwq
= pool
->gcwq
;
1212 BUG_ON(worker
->flags
& WORKER_IDLE
);
1213 BUG_ON(!list_empty(&worker
->entry
) &&
1214 (worker
->hentry
.next
|| worker
->hentry
.pprev
));
1216 /* can't use worker_set_flags(), also called from start_worker() */
1217 worker
->flags
|= WORKER_IDLE
;
1219 worker
->last_active
= jiffies
;
1221 /* idle_list is LIFO */
1222 list_add(&worker
->entry
, &pool
->idle_list
);
1224 if (likely(!(worker
->flags
& WORKER_ROGUE
))) {
1225 if (too_many_workers(pool
) && !timer_pending(&pool
->idle_timer
))
1226 mod_timer(&pool
->idle_timer
,
1227 jiffies
+ IDLE_WORKER_TIMEOUT
);
1229 wake_up_all(&gcwq
->trustee_wait
);
1232 * Sanity check nr_running. Because trustee releases gcwq->lock
1233 * between setting %WORKER_ROGUE and zapping nr_running, the
1234 * warning may trigger spuriously. Check iff trustee is idle.
1236 WARN_ON_ONCE(gcwq
->trustee_state
== TRUSTEE_DONE
&&
1237 pool
->nr_workers
== pool
->nr_idle
&&
1238 atomic_read(get_pool_nr_running(pool
)));
1242 * worker_leave_idle - leave idle state
1243 * @worker: worker which is leaving idle state
1245 * @worker is leaving idle state. Update stats.
1248 * spin_lock_irq(gcwq->lock).
1250 static void worker_leave_idle(struct worker
*worker
)
1252 struct worker_pool
*pool
= worker
->pool
;
1254 BUG_ON(!(worker
->flags
& WORKER_IDLE
));
1255 worker_clr_flags(worker
, WORKER_IDLE
);
1257 list_del_init(&worker
->entry
);
1261 * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq
1264 * Works which are scheduled while the cpu is online must at least be
1265 * scheduled to a worker which is bound to the cpu so that if they are
1266 * flushed from cpu callbacks while cpu is going down, they are
1267 * guaranteed to execute on the cpu.
1269 * This function is to be used by rogue workers and rescuers to bind
1270 * themselves to the target cpu and may race with cpu going down or
1271 * coming online. kthread_bind() can't be used because it may put the
1272 * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
1273 * verbatim as it's best effort and blocking and gcwq may be
1274 * [dis]associated in the meantime.
1276 * This function tries set_cpus_allowed() and locks gcwq and verifies
1277 * the binding against GCWQ_DISASSOCIATED which is set during
1278 * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters
1279 * idle state or fetches works without dropping lock, it can guarantee
1280 * the scheduling requirement described in the first paragraph.
1283 * Might sleep. Called without any lock but returns with gcwq->lock
1287 * %true if the associated gcwq is online (@worker is successfully
1288 * bound), %false if offline.
1290 static bool worker_maybe_bind_and_lock(struct worker
*worker
)
1291 __acquires(&gcwq
->lock
)
1293 struct global_cwq
*gcwq
= worker
->pool
->gcwq
;
1294 struct task_struct
*task
= worker
->task
;
1298 * The following call may fail, succeed or succeed
1299 * without actually migrating the task to the cpu if
1300 * it races with cpu hotunplug operation. Verify
1301 * against GCWQ_DISASSOCIATED.
1303 if (!(gcwq
->flags
& GCWQ_DISASSOCIATED
))
1304 set_cpus_allowed_ptr(task
, get_cpu_mask(gcwq
->cpu
));
1306 spin_lock_irq(&gcwq
->lock
);
1307 if (gcwq
->flags
& GCWQ_DISASSOCIATED
)
1309 if (task_cpu(task
) == gcwq
->cpu
&&
1310 cpumask_equal(¤t
->cpus_allowed
,
1311 get_cpu_mask(gcwq
->cpu
)))
1313 spin_unlock_irq(&gcwq
->lock
);
1316 * We've raced with CPU hot[un]plug. Give it a breather
1317 * and retry migration. cond_resched() is required here;
1318 * otherwise, we might deadlock against cpu_stop trying to
1319 * bring down the CPU on non-preemptive kernel.
1327 * Function for worker->rebind_work used to rebind rogue busy workers
1328 * to the associated cpu which is coming back online. This is
1329 * scheduled by cpu up but can race with other cpu hotplug operations
1330 * and may be executed twice without intervening cpu down.
1332 static void worker_rebind_fn(struct work_struct
*work
)
1334 struct worker
*worker
= container_of(work
, struct worker
, rebind_work
);
1335 struct global_cwq
*gcwq
= worker
->pool
->gcwq
;
1337 if (worker_maybe_bind_and_lock(worker
))
1338 worker_clr_flags(worker
, WORKER_REBIND
);
1340 spin_unlock_irq(&gcwq
->lock
);
1343 static struct worker
*alloc_worker(void)
1345 struct worker
*worker
;
1347 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
1349 INIT_LIST_HEAD(&worker
->entry
);
1350 INIT_LIST_HEAD(&worker
->scheduled
);
1351 INIT_WORK(&worker
->rebind_work
, worker_rebind_fn
);
1352 /* on creation a worker is in !idle && prep state */
1353 worker
->flags
= WORKER_PREP
;
1359 * create_worker - create a new workqueue worker
1360 * @pool: pool the new worker will belong to
1361 * @bind: whether to set affinity to @cpu or not
1363 * Create a new worker which is bound to @pool. The returned worker
1364 * can be started by calling start_worker() or destroyed using
1368 * Might sleep. Does GFP_KERNEL allocations.
1371 * Pointer to the newly created worker.
1373 static struct worker
*create_worker(struct worker_pool
*pool
, bool bind
)
1375 struct global_cwq
*gcwq
= pool
->gcwq
;
1376 bool on_unbound_cpu
= gcwq
->cpu
== WORK_CPU_UNBOUND
;
1377 struct worker
*worker
= NULL
;
1380 spin_lock_irq(&gcwq
->lock
);
1381 while (ida_get_new(&pool
->worker_ida
, &id
)) {
1382 spin_unlock_irq(&gcwq
->lock
);
1383 if (!ida_pre_get(&pool
->worker_ida
, GFP_KERNEL
))
1385 spin_lock_irq(&gcwq
->lock
);
1387 spin_unlock_irq(&gcwq
->lock
);
1389 worker
= alloc_worker();
1393 worker
->pool
= pool
;
1396 if (!on_unbound_cpu
)
1397 worker
->task
= kthread_create_on_node(worker_thread
,
1399 cpu_to_node(gcwq
->cpu
),
1400 "kworker/%u:%d", gcwq
->cpu
, id
);
1402 worker
->task
= kthread_create(worker_thread
, worker
,
1403 "kworker/u:%d", id
);
1404 if (IS_ERR(worker
->task
))
1408 * A rogue worker will become a regular one if CPU comes
1409 * online later on. Make sure every worker has
1410 * PF_THREAD_BOUND set.
1412 if (bind
&& !on_unbound_cpu
)
1413 kthread_bind(worker
->task
, gcwq
->cpu
);
1415 worker
->task
->flags
|= PF_THREAD_BOUND
;
1417 worker
->flags
|= WORKER_UNBOUND
;
1423 spin_lock_irq(&gcwq
->lock
);
1424 ida_remove(&pool
->worker_ida
, id
);
1425 spin_unlock_irq(&gcwq
->lock
);
1432 * start_worker - start a newly created worker
1433 * @worker: worker to start
1435 * Make the gcwq aware of @worker and start it.
1438 * spin_lock_irq(gcwq->lock).
1440 static void start_worker(struct worker
*worker
)
1442 worker
->flags
|= WORKER_STARTED
;
1443 worker
->pool
->nr_workers
++;
1444 worker_enter_idle(worker
);
1445 wake_up_process(worker
->task
);
1449 * destroy_worker - destroy a workqueue worker
1450 * @worker: worker to be destroyed
1452 * Destroy @worker and adjust @gcwq stats accordingly.
1455 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1457 static void destroy_worker(struct worker
*worker
)
1459 struct worker_pool
*pool
= worker
->pool
;
1460 struct global_cwq
*gcwq
= pool
->gcwq
;
1461 int id
= worker
->id
;
1463 /* sanity check frenzy */
1464 BUG_ON(worker
->current_work
);
1465 BUG_ON(!list_empty(&worker
->scheduled
));
1467 if (worker
->flags
& WORKER_STARTED
)
1469 if (worker
->flags
& WORKER_IDLE
)
1472 list_del_init(&worker
->entry
);
1473 worker
->flags
|= WORKER_DIE
;
1475 spin_unlock_irq(&gcwq
->lock
);
1477 kthread_stop(worker
->task
);
1480 spin_lock_irq(&gcwq
->lock
);
1481 ida_remove(&pool
->worker_ida
, id
);
1484 static void idle_worker_timeout(unsigned long __pool
)
1486 struct worker_pool
*pool
= (void *)__pool
;
1487 struct global_cwq
*gcwq
= pool
->gcwq
;
1489 spin_lock_irq(&gcwq
->lock
);
1491 if (too_many_workers(pool
)) {
1492 struct worker
*worker
;
1493 unsigned long expires
;
1495 /* idle_list is kept in LIFO order, check the last one */
1496 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
1497 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
1499 if (time_before(jiffies
, expires
))
1500 mod_timer(&pool
->idle_timer
, expires
);
1502 /* it's been idle for too long, wake up manager */
1503 gcwq
->flags
|= GCWQ_MANAGE_WORKERS
;
1504 wake_up_worker(pool
);
1508 spin_unlock_irq(&gcwq
->lock
);
1511 static bool send_mayday(struct work_struct
*work
)
1513 struct cpu_workqueue_struct
*cwq
= get_work_cwq(work
);
1514 struct workqueue_struct
*wq
= cwq
->wq
;
1517 if (!(wq
->flags
& WQ_RESCUER
))
1520 /* mayday mayday mayday */
1521 cpu
= cwq
->pool
->gcwq
->cpu
;
1522 /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */
1523 if (cpu
== WORK_CPU_UNBOUND
)
1525 if (!mayday_test_and_set_cpu(cpu
, wq
->mayday_mask
))
1526 wake_up_process(wq
->rescuer
->task
);
1530 static void gcwq_mayday_timeout(unsigned long __pool
)
1532 struct worker_pool
*pool
= (void *)__pool
;
1533 struct global_cwq
*gcwq
= pool
->gcwq
;
1534 struct work_struct
*work
;
1536 spin_lock_irq(&gcwq
->lock
);
1538 if (need_to_create_worker(pool
)) {
1540 * We've been trying to create a new worker but
1541 * haven't been successful. We might be hitting an
1542 * allocation deadlock. Send distress signals to
1545 list_for_each_entry(work
, &pool
->worklist
, entry
)
1549 spin_unlock_irq(&gcwq
->lock
);
1551 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INTERVAL
);
1555 * maybe_create_worker - create a new worker if necessary
1556 * @pool: pool to create a new worker for
1558 * Create a new worker for @pool if necessary. @pool is guaranteed to
1559 * have at least one idle worker on return from this function. If
1560 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1561 * sent to all rescuers with works scheduled on @pool to resolve
1562 * possible allocation deadlock.
1564 * On return, need_to_create_worker() is guaranteed to be false and
1565 * may_start_working() true.
1568 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1569 * multiple times. Does GFP_KERNEL allocations. Called only from
1573 * false if no action was taken and gcwq->lock stayed locked, true
1576 static bool maybe_create_worker(struct worker_pool
*pool
)
1577 __releases(&gcwq
->lock
)
1578 __acquires(&gcwq
->lock
)
1580 struct global_cwq
*gcwq
= pool
->gcwq
;
1582 if (!need_to_create_worker(pool
))
1585 spin_unlock_irq(&gcwq
->lock
);
1587 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1588 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INITIAL_TIMEOUT
);
1591 struct worker
*worker
;
1593 worker
= create_worker(pool
, true);
1595 del_timer_sync(&pool
->mayday_timer
);
1596 spin_lock_irq(&gcwq
->lock
);
1597 start_worker(worker
);
1598 BUG_ON(need_to_create_worker(pool
));
1602 if (!need_to_create_worker(pool
))
1605 __set_current_state(TASK_INTERRUPTIBLE
);
1606 schedule_timeout(CREATE_COOLDOWN
);
1608 if (!need_to_create_worker(pool
))
1612 del_timer_sync(&pool
->mayday_timer
);
1613 spin_lock_irq(&gcwq
->lock
);
1614 if (need_to_create_worker(pool
))
1620 * maybe_destroy_worker - destroy workers which have been idle for a while
1621 * @pool: pool to destroy workers for
1623 * Destroy @pool workers which have been idle for longer than
1624 * IDLE_WORKER_TIMEOUT.
1627 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1628 * multiple times. Called only from manager.
1631 * false if no action was taken and gcwq->lock stayed locked, true
1634 static bool maybe_destroy_workers(struct worker_pool
*pool
)
1638 while (too_many_workers(pool
)) {
1639 struct worker
*worker
;
1640 unsigned long expires
;
1642 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
1643 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
1645 if (time_before(jiffies
, expires
)) {
1646 mod_timer(&pool
->idle_timer
, expires
);
1650 destroy_worker(worker
);
1658 * manage_workers - manage worker pool
1661 * Assume the manager role and manage gcwq worker pool @worker belongs
1662 * to. At any given time, there can be only zero or one manager per
1663 * gcwq. The exclusion is handled automatically by this function.
1665 * The caller can safely start processing works on false return. On
1666 * true return, it's guaranteed that need_to_create_worker() is false
1667 * and may_start_working() is true.
1670 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1671 * multiple times. Does GFP_KERNEL allocations.
1674 * false if no action was taken and gcwq->lock stayed locked, true if
1675 * some action was taken.
1677 static bool manage_workers(struct worker
*worker
)
1679 struct worker_pool
*pool
= worker
->pool
;
1680 struct global_cwq
*gcwq
= pool
->gcwq
;
1683 if (gcwq
->flags
& GCWQ_MANAGING_WORKERS
)
1686 gcwq
->flags
&= ~GCWQ_MANAGE_WORKERS
;
1687 gcwq
->flags
|= GCWQ_MANAGING_WORKERS
;
1690 * Destroy and then create so that may_start_working() is true
1693 ret
|= maybe_destroy_workers(pool
);
1694 ret
|= maybe_create_worker(pool
);
1696 gcwq
->flags
&= ~GCWQ_MANAGING_WORKERS
;
1699 * The trustee might be waiting to take over the manager
1700 * position, tell it we're done.
1702 if (unlikely(gcwq
->trustee
))
1703 wake_up_all(&gcwq
->trustee_wait
);
1709 * move_linked_works - move linked works to a list
1710 * @work: start of series of works to be scheduled
1711 * @head: target list to append @work to
1712 * @nextp: out paramter for nested worklist walking
1714 * Schedule linked works starting from @work to @head. Work series to
1715 * be scheduled starts at @work and includes any consecutive work with
1716 * WORK_STRUCT_LINKED set in its predecessor.
1718 * If @nextp is not NULL, it's updated to point to the next work of
1719 * the last scheduled work. This allows move_linked_works() to be
1720 * nested inside outer list_for_each_entry_safe().
1723 * spin_lock_irq(gcwq->lock).
1725 static void move_linked_works(struct work_struct
*work
, struct list_head
*head
,
1726 struct work_struct
**nextp
)
1728 struct work_struct
*n
;
1731 * Linked worklist will always end before the end of the list,
1732 * use NULL for list head.
1734 list_for_each_entry_safe_from(work
, n
, NULL
, entry
) {
1735 list_move_tail(&work
->entry
, head
);
1736 if (!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))
1741 * If we're already inside safe list traversal and have moved
1742 * multiple works to the scheduled queue, the next position
1743 * needs to be updated.
1749 static void cwq_activate_first_delayed(struct cpu_workqueue_struct
*cwq
)
1751 struct work_struct
*work
= list_first_entry(&cwq
->delayed_works
,
1752 struct work_struct
, entry
);
1753 struct list_head
*pos
= pool_determine_ins_pos(cwq
->pool
, cwq
);
1755 trace_workqueue_activate_work(work
);
1756 move_linked_works(work
, pos
, NULL
);
1757 __clear_bit(WORK_STRUCT_DELAYED_BIT
, work_data_bits(work
));
1762 * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight
1763 * @cwq: cwq of interest
1764 * @color: color of work which left the queue
1765 * @delayed: for a delayed work
1767 * A work either has completed or is removed from pending queue,
1768 * decrement nr_in_flight of its cwq and handle workqueue flushing.
1771 * spin_lock_irq(gcwq->lock).
1773 static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct
*cwq
, int color
,
1776 /* ignore uncolored works */
1777 if (color
== WORK_NO_COLOR
)
1780 cwq
->nr_in_flight
[color
]--;
1784 if (!list_empty(&cwq
->delayed_works
)) {
1785 /* one down, submit a delayed one */
1786 if (cwq
->nr_active
< cwq
->max_active
)
1787 cwq_activate_first_delayed(cwq
);
1791 /* is flush in progress and are we at the flushing tip? */
1792 if (likely(cwq
->flush_color
!= color
))
1795 /* are there still in-flight works? */
1796 if (cwq
->nr_in_flight
[color
])
1799 /* this cwq is done, clear flush_color */
1800 cwq
->flush_color
= -1;
1803 * If this was the last cwq, wake up the first flusher. It
1804 * will handle the rest.
1806 if (atomic_dec_and_test(&cwq
->wq
->nr_cwqs_to_flush
))
1807 complete(&cwq
->wq
->first_flusher
->done
);
1811 * process_one_work - process single work
1813 * @work: work to process
1815 * Process @work. This function contains all the logics necessary to
1816 * process a single work including synchronization against and
1817 * interaction with other workers on the same cpu, queueing and
1818 * flushing. As long as context requirement is met, any worker can
1819 * call this function to process a work.
1822 * spin_lock_irq(gcwq->lock) which is released and regrabbed.
1824 static void process_one_work(struct worker
*worker
, struct work_struct
*work
)
1825 __releases(&gcwq
->lock
)
1826 __acquires(&gcwq
->lock
)
1828 struct cpu_workqueue_struct
*cwq
= get_work_cwq(work
);
1829 struct worker_pool
*pool
= worker
->pool
;
1830 struct global_cwq
*gcwq
= pool
->gcwq
;
1831 struct hlist_head
*bwh
= busy_worker_head(gcwq
, work
);
1832 bool cpu_intensive
= cwq
->wq
->flags
& WQ_CPU_INTENSIVE
;
1833 work_func_t f
= work
->func
;
1835 struct worker
*collision
;
1836 #ifdef CONFIG_LOCKDEP
1838 * It is permissible to free the struct work_struct from
1839 * inside the function that is called from it, this we need to
1840 * take into account for lockdep too. To avoid bogus "held
1841 * lock freed" warnings as well as problems when looking into
1842 * work->lockdep_map, make a copy and use that here.
1844 struct lockdep_map lockdep_map
;
1846 lockdep_copy_map(&lockdep_map
, &work
->lockdep_map
);
1849 * A single work shouldn't be executed concurrently by
1850 * multiple workers on a single cpu. Check whether anyone is
1851 * already processing the work. If so, defer the work to the
1852 * currently executing one.
1854 collision
= __find_worker_executing_work(gcwq
, bwh
, work
);
1855 if (unlikely(collision
)) {
1856 move_linked_works(work
, &collision
->scheduled
, NULL
);
1860 /* claim and process */
1861 debug_work_deactivate(work
);
1862 hlist_add_head(&worker
->hentry
, bwh
);
1863 worker
->current_work
= work
;
1864 worker
->current_cwq
= cwq
;
1865 work_color
= get_work_color(work
);
1867 /* record the current cpu number in the work data and dequeue */
1868 set_work_cpu(work
, gcwq
->cpu
);
1869 list_del_init(&work
->entry
);
1872 * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI,
1873 * wake up another worker; otherwise, clear HIGHPRI_PENDING.
1875 if (unlikely(gcwq
->flags
& GCWQ_HIGHPRI_PENDING
)) {
1876 struct work_struct
*nwork
= list_first_entry(&pool
->worklist
,
1877 struct work_struct
, entry
);
1879 if (!list_empty(&pool
->worklist
) &&
1880 get_work_cwq(nwork
)->wq
->flags
& WQ_HIGHPRI
)
1881 wake_up_worker(pool
);
1883 gcwq
->flags
&= ~GCWQ_HIGHPRI_PENDING
;
1887 * CPU intensive works don't participate in concurrency
1888 * management. They're the scheduler's responsibility.
1890 if (unlikely(cpu_intensive
))
1891 worker_set_flags(worker
, WORKER_CPU_INTENSIVE
, true);
1894 * Unbound gcwq isn't concurrency managed and work items should be
1895 * executed ASAP. Wake up another worker if necessary.
1897 if ((worker
->flags
& WORKER_UNBOUND
) && need_more_worker(pool
))
1898 wake_up_worker(pool
);
1900 spin_unlock_irq(&gcwq
->lock
);
1902 work_clear_pending(work
);
1903 lock_map_acquire_read(&cwq
->wq
->lockdep_map
);
1904 lock_map_acquire(&lockdep_map
);
1905 trace_workqueue_execute_start(work
);
1908 * While we must be careful to not use "work" after this, the trace
1909 * point will only record its address.
1911 trace_workqueue_execute_end(work
);
1912 lock_map_release(&lockdep_map
);
1913 lock_map_release(&cwq
->wq
->lockdep_map
);
1915 if (unlikely(in_atomic() || lockdep_depth(current
) > 0)) {
1916 printk(KERN_ERR
"BUG: workqueue leaked lock or atomic: "
1918 current
->comm
, preempt_count(), task_pid_nr(current
));
1919 printk(KERN_ERR
" last function: ");
1920 print_symbol("%s\n", (unsigned long)f
);
1921 debug_show_held_locks(current
);
1925 spin_lock_irq(&gcwq
->lock
);
1927 /* clear cpu intensive status */
1928 if (unlikely(cpu_intensive
))
1929 worker_clr_flags(worker
, WORKER_CPU_INTENSIVE
);
1931 /* we're done with it, release */
1932 hlist_del_init(&worker
->hentry
);
1933 worker
->current_work
= NULL
;
1934 worker
->current_cwq
= NULL
;
1935 cwq_dec_nr_in_flight(cwq
, work_color
, false);
1939 * process_scheduled_works - process scheduled works
1942 * Process all scheduled works. Please note that the scheduled list
1943 * may change while processing a work, so this function repeatedly
1944 * fetches a work from the top and executes it.
1947 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
1950 static void process_scheduled_works(struct worker
*worker
)
1952 while (!list_empty(&worker
->scheduled
)) {
1953 struct work_struct
*work
= list_first_entry(&worker
->scheduled
,
1954 struct work_struct
, entry
);
1955 process_one_work(worker
, work
);
1960 * worker_thread - the worker thread function
1963 * The gcwq worker thread function. There's a single dynamic pool of
1964 * these per each cpu. These workers process all works regardless of
1965 * their specific target workqueue. The only exception is works which
1966 * belong to workqueues with a rescuer which will be explained in
1969 static int worker_thread(void *__worker
)
1971 struct worker
*worker
= __worker
;
1972 struct worker_pool
*pool
= worker
->pool
;
1973 struct global_cwq
*gcwq
= pool
->gcwq
;
1975 /* tell the scheduler that this is a workqueue worker */
1976 worker
->task
->flags
|= PF_WQ_WORKER
;
1978 spin_lock_irq(&gcwq
->lock
);
1980 /* DIE can be set only while we're idle, checking here is enough */
1981 if (worker
->flags
& WORKER_DIE
) {
1982 spin_unlock_irq(&gcwq
->lock
);
1983 worker
->task
->flags
&= ~PF_WQ_WORKER
;
1987 worker_leave_idle(worker
);
1989 /* no more worker necessary? */
1990 if (!need_more_worker(pool
))
1993 /* do we need to manage? */
1994 if (unlikely(!may_start_working(pool
)) && manage_workers(worker
))
1998 * ->scheduled list can only be filled while a worker is
1999 * preparing to process a work or actually processing it.
2000 * Make sure nobody diddled with it while I was sleeping.
2002 BUG_ON(!list_empty(&worker
->scheduled
));
2005 * When control reaches this point, we're guaranteed to have
2006 * at least one idle worker or that someone else has already
2007 * assumed the manager role.
2009 worker_clr_flags(worker
, WORKER_PREP
);
2012 struct work_struct
*work
=
2013 list_first_entry(&pool
->worklist
,
2014 struct work_struct
, entry
);
2016 if (likely(!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))) {
2017 /* optimization path, not strictly necessary */
2018 process_one_work(worker
, work
);
2019 if (unlikely(!list_empty(&worker
->scheduled
)))
2020 process_scheduled_works(worker
);
2022 move_linked_works(work
, &worker
->scheduled
, NULL
);
2023 process_scheduled_works(worker
);
2025 } while (keep_working(pool
));
2027 worker_set_flags(worker
, WORKER_PREP
, false);
2029 if (unlikely(need_to_manage_workers(pool
)) && manage_workers(worker
))
2033 * gcwq->lock is held and there's no work to process and no
2034 * need to manage, sleep. Workers are woken up only while
2035 * holding gcwq->lock or from local cpu, so setting the
2036 * current state before releasing gcwq->lock is enough to
2037 * prevent losing any event.
2039 worker_enter_idle(worker
);
2040 __set_current_state(TASK_INTERRUPTIBLE
);
2041 spin_unlock_irq(&gcwq
->lock
);
2047 * rescuer_thread - the rescuer thread function
2048 * @__wq: the associated workqueue
2050 * Workqueue rescuer thread function. There's one rescuer for each
2051 * workqueue which has WQ_RESCUER set.
2053 * Regular work processing on a gcwq may block trying to create a new
2054 * worker which uses GFP_KERNEL allocation which has slight chance of
2055 * developing into deadlock if some works currently on the same queue
2056 * need to be processed to satisfy the GFP_KERNEL allocation. This is
2057 * the problem rescuer solves.
2059 * When such condition is possible, the gcwq summons rescuers of all
2060 * workqueues which have works queued on the gcwq and let them process
2061 * those works so that forward progress can be guaranteed.
2063 * This should happen rarely.
2065 static int rescuer_thread(void *__wq
)
2067 struct workqueue_struct
*wq
= __wq
;
2068 struct worker
*rescuer
= wq
->rescuer
;
2069 struct list_head
*scheduled
= &rescuer
->scheduled
;
2070 bool is_unbound
= wq
->flags
& WQ_UNBOUND
;
2073 set_user_nice(current
, RESCUER_NICE_LEVEL
);
2075 set_current_state(TASK_INTERRUPTIBLE
);
2077 if (kthread_should_stop())
2081 * See whether any cpu is asking for help. Unbounded
2082 * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND.
2084 for_each_mayday_cpu(cpu
, wq
->mayday_mask
) {
2085 unsigned int tcpu
= is_unbound
? WORK_CPU_UNBOUND
: cpu
;
2086 struct cpu_workqueue_struct
*cwq
= get_cwq(tcpu
, wq
);
2087 struct worker_pool
*pool
= cwq
->pool
;
2088 struct global_cwq
*gcwq
= pool
->gcwq
;
2089 struct work_struct
*work
, *n
;
2091 __set_current_state(TASK_RUNNING
);
2092 mayday_clear_cpu(cpu
, wq
->mayday_mask
);
2094 /* migrate to the target cpu if possible */
2095 rescuer
->pool
= pool
;
2096 worker_maybe_bind_and_lock(rescuer
);
2099 * Slurp in all works issued via this workqueue and
2102 BUG_ON(!list_empty(&rescuer
->scheduled
));
2103 list_for_each_entry_safe(work
, n
, &pool
->worklist
, entry
)
2104 if (get_work_cwq(work
) == cwq
)
2105 move_linked_works(work
, scheduled
, &n
);
2107 process_scheduled_works(rescuer
);
2110 * Leave this gcwq. If keep_working() is %true, notify a
2111 * regular worker; otherwise, we end up with 0 concurrency
2112 * and stalling the execution.
2114 if (keep_working(pool
))
2115 wake_up_worker(pool
);
2117 spin_unlock_irq(&gcwq
->lock
);
2125 struct work_struct work
;
2126 struct completion done
;
2129 static void wq_barrier_func(struct work_struct
*work
)
2131 struct wq_barrier
*barr
= container_of(work
, struct wq_barrier
, work
);
2132 complete(&barr
->done
);
2136 * insert_wq_barrier - insert a barrier work
2137 * @cwq: cwq to insert barrier into
2138 * @barr: wq_barrier to insert
2139 * @target: target work to attach @barr to
2140 * @worker: worker currently executing @target, NULL if @target is not executing
2142 * @barr is linked to @target such that @barr is completed only after
2143 * @target finishes execution. Please note that the ordering
2144 * guarantee is observed only with respect to @target and on the local
2147 * Currently, a queued barrier can't be canceled. This is because
2148 * try_to_grab_pending() can't determine whether the work to be
2149 * grabbed is at the head of the queue and thus can't clear LINKED
2150 * flag of the previous work while there must be a valid next work
2151 * after a work with LINKED flag set.
2153 * Note that when @worker is non-NULL, @target may be modified
2154 * underneath us, so we can't reliably determine cwq from @target.
2157 * spin_lock_irq(gcwq->lock).
2159 static void insert_wq_barrier(struct cpu_workqueue_struct
*cwq
,
2160 struct wq_barrier
*barr
,
2161 struct work_struct
*target
, struct worker
*worker
)
2163 struct list_head
*head
;
2164 unsigned int linked
= 0;
2167 * debugobject calls are safe here even with gcwq->lock locked
2168 * as we know for sure that this will not trigger any of the
2169 * checks and call back into the fixup functions where we
2172 INIT_WORK_ONSTACK(&barr
->work
, wq_barrier_func
);
2173 __set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(&barr
->work
));
2174 init_completion(&barr
->done
);
2177 * If @target is currently being executed, schedule the
2178 * barrier to the worker; otherwise, put it after @target.
2181 head
= worker
->scheduled
.next
;
2183 unsigned long *bits
= work_data_bits(target
);
2185 head
= target
->entry
.next
;
2186 /* there can already be other linked works, inherit and set */
2187 linked
= *bits
& WORK_STRUCT_LINKED
;
2188 __set_bit(WORK_STRUCT_LINKED_BIT
, bits
);
2191 debug_work_activate(&barr
->work
);
2192 insert_work(cwq
, &barr
->work
, head
,
2193 work_color_to_flags(WORK_NO_COLOR
) | linked
);
2197 * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing
2198 * @wq: workqueue being flushed
2199 * @flush_color: new flush color, < 0 for no-op
2200 * @work_color: new work color, < 0 for no-op
2202 * Prepare cwqs for workqueue flushing.
2204 * If @flush_color is non-negative, flush_color on all cwqs should be
2205 * -1. If no cwq has in-flight commands at the specified color, all
2206 * cwq->flush_color's stay at -1 and %false is returned. If any cwq
2207 * has in flight commands, its cwq->flush_color is set to
2208 * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq
2209 * wakeup logic is armed and %true is returned.
2211 * The caller should have initialized @wq->first_flusher prior to
2212 * calling this function with non-negative @flush_color. If
2213 * @flush_color is negative, no flush color update is done and %false
2216 * If @work_color is non-negative, all cwqs should have the same
2217 * work_color which is previous to @work_color and all will be
2218 * advanced to @work_color.
2221 * mutex_lock(wq->flush_mutex).
2224 * %true if @flush_color >= 0 and there's something to flush. %false
2227 static bool flush_workqueue_prep_cwqs(struct workqueue_struct
*wq
,
2228 int flush_color
, int work_color
)
2233 if (flush_color
>= 0) {
2234 BUG_ON(atomic_read(&wq
->nr_cwqs_to_flush
));
2235 atomic_set(&wq
->nr_cwqs_to_flush
, 1);
2238 for_each_cwq_cpu(cpu
, wq
) {
2239 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
2240 struct global_cwq
*gcwq
= cwq
->pool
->gcwq
;
2242 spin_lock_irq(&gcwq
->lock
);
2244 if (flush_color
>= 0) {
2245 BUG_ON(cwq
->flush_color
!= -1);
2247 if (cwq
->nr_in_flight
[flush_color
]) {
2248 cwq
->flush_color
= flush_color
;
2249 atomic_inc(&wq
->nr_cwqs_to_flush
);
2254 if (work_color
>= 0) {
2255 BUG_ON(work_color
!= work_next_color(cwq
->work_color
));
2256 cwq
->work_color
= work_color
;
2259 spin_unlock_irq(&gcwq
->lock
);
2262 if (flush_color
>= 0 && atomic_dec_and_test(&wq
->nr_cwqs_to_flush
))
2263 complete(&wq
->first_flusher
->done
);
2269 * flush_workqueue - ensure that any scheduled work has run to completion.
2270 * @wq: workqueue to flush
2272 * Forces execution of the workqueue and blocks until its completion.
2273 * This is typically used in driver shutdown handlers.
2275 * We sleep until all works which were queued on entry have been handled,
2276 * but we are not livelocked by new incoming ones.
2278 void flush_workqueue(struct workqueue_struct
*wq
)
2280 struct wq_flusher this_flusher
= {
2281 .list
= LIST_HEAD_INIT(this_flusher
.list
),
2283 .done
= COMPLETION_INITIALIZER_ONSTACK(this_flusher
.done
),
2287 lock_map_acquire(&wq
->lockdep_map
);
2288 lock_map_release(&wq
->lockdep_map
);
2290 mutex_lock(&wq
->flush_mutex
);
2293 * Start-to-wait phase
2295 next_color
= work_next_color(wq
->work_color
);
2297 if (next_color
!= wq
->flush_color
) {
2299 * Color space is not full. The current work_color
2300 * becomes our flush_color and work_color is advanced
2303 BUG_ON(!list_empty(&wq
->flusher_overflow
));
2304 this_flusher
.flush_color
= wq
->work_color
;
2305 wq
->work_color
= next_color
;
2307 if (!wq
->first_flusher
) {
2308 /* no flush in progress, become the first flusher */
2309 BUG_ON(wq
->flush_color
!= this_flusher
.flush_color
);
2311 wq
->first_flusher
= &this_flusher
;
2313 if (!flush_workqueue_prep_cwqs(wq
, wq
->flush_color
,
2315 /* nothing to flush, done */
2316 wq
->flush_color
= next_color
;
2317 wq
->first_flusher
= NULL
;
2322 BUG_ON(wq
->flush_color
== this_flusher
.flush_color
);
2323 list_add_tail(&this_flusher
.list
, &wq
->flusher_queue
);
2324 flush_workqueue_prep_cwqs(wq
, -1, wq
->work_color
);
2328 * Oops, color space is full, wait on overflow queue.
2329 * The next flush completion will assign us
2330 * flush_color and transfer to flusher_queue.
2332 list_add_tail(&this_flusher
.list
, &wq
->flusher_overflow
);
2335 mutex_unlock(&wq
->flush_mutex
);
2337 wait_for_completion(&this_flusher
.done
);
2340 * Wake-up-and-cascade phase
2342 * First flushers are responsible for cascading flushes and
2343 * handling overflow. Non-first flushers can simply return.
2345 if (wq
->first_flusher
!= &this_flusher
)
2348 mutex_lock(&wq
->flush_mutex
);
2350 /* we might have raced, check again with mutex held */
2351 if (wq
->first_flusher
!= &this_flusher
)
2354 wq
->first_flusher
= NULL
;
2356 BUG_ON(!list_empty(&this_flusher
.list
));
2357 BUG_ON(wq
->flush_color
!= this_flusher
.flush_color
);
2360 struct wq_flusher
*next
, *tmp
;
2362 /* complete all the flushers sharing the current flush color */
2363 list_for_each_entry_safe(next
, tmp
, &wq
->flusher_queue
, list
) {
2364 if (next
->flush_color
!= wq
->flush_color
)
2366 list_del_init(&next
->list
);
2367 complete(&next
->done
);
2370 BUG_ON(!list_empty(&wq
->flusher_overflow
) &&
2371 wq
->flush_color
!= work_next_color(wq
->work_color
));
2373 /* this flush_color is finished, advance by one */
2374 wq
->flush_color
= work_next_color(wq
->flush_color
);
2376 /* one color has been freed, handle overflow queue */
2377 if (!list_empty(&wq
->flusher_overflow
)) {
2379 * Assign the same color to all overflowed
2380 * flushers, advance work_color and append to
2381 * flusher_queue. This is the start-to-wait
2382 * phase for these overflowed flushers.
2384 list_for_each_entry(tmp
, &wq
->flusher_overflow
, list
)
2385 tmp
->flush_color
= wq
->work_color
;
2387 wq
->work_color
= work_next_color(wq
->work_color
);
2389 list_splice_tail_init(&wq
->flusher_overflow
,
2390 &wq
->flusher_queue
);
2391 flush_workqueue_prep_cwqs(wq
, -1, wq
->work_color
);
2394 if (list_empty(&wq
->flusher_queue
)) {
2395 BUG_ON(wq
->flush_color
!= wq
->work_color
);
2400 * Need to flush more colors. Make the next flusher
2401 * the new first flusher and arm cwqs.
2403 BUG_ON(wq
->flush_color
== wq
->work_color
);
2404 BUG_ON(wq
->flush_color
!= next
->flush_color
);
2406 list_del_init(&next
->list
);
2407 wq
->first_flusher
= next
;
2409 if (flush_workqueue_prep_cwqs(wq
, wq
->flush_color
, -1))
2413 * Meh... this color is already done, clear first
2414 * flusher and repeat cascading.
2416 wq
->first_flusher
= NULL
;
2420 mutex_unlock(&wq
->flush_mutex
);
2422 EXPORT_SYMBOL_GPL(flush_workqueue
);
2425 * drain_workqueue - drain a workqueue
2426 * @wq: workqueue to drain
2428 * Wait until the workqueue becomes empty. While draining is in progress,
2429 * only chain queueing is allowed. IOW, only currently pending or running
2430 * work items on @wq can queue further work items on it. @wq is flushed
2431 * repeatedly until it becomes empty. The number of flushing is detemined
2432 * by the depth of chaining and should be relatively short. Whine if it
2435 void drain_workqueue(struct workqueue_struct
*wq
)
2437 unsigned int flush_cnt
= 0;
2441 * __queue_work() needs to test whether there are drainers, is much
2442 * hotter than drain_workqueue() and already looks at @wq->flags.
2443 * Use WQ_DRAINING so that queue doesn't have to check nr_drainers.
2445 spin_lock(&workqueue_lock
);
2446 if (!wq
->nr_drainers
++)
2447 wq
->flags
|= WQ_DRAINING
;
2448 spin_unlock(&workqueue_lock
);
2450 flush_workqueue(wq
);
2452 for_each_cwq_cpu(cpu
, wq
) {
2453 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
2456 spin_lock_irq(&cwq
->pool
->gcwq
->lock
);
2457 drained
= !cwq
->nr_active
&& list_empty(&cwq
->delayed_works
);
2458 spin_unlock_irq(&cwq
->pool
->gcwq
->lock
);
2463 if (++flush_cnt
== 10 ||
2464 (flush_cnt
% 100 == 0 && flush_cnt
<= 1000))
2465 pr_warning("workqueue %s: flush on destruction isn't complete after %u tries\n",
2466 wq
->name
, flush_cnt
);
2470 spin_lock(&workqueue_lock
);
2471 if (!--wq
->nr_drainers
)
2472 wq
->flags
&= ~WQ_DRAINING
;
2473 spin_unlock(&workqueue_lock
);
2475 EXPORT_SYMBOL_GPL(drain_workqueue
);
2477 static bool start_flush_work(struct work_struct
*work
, struct wq_barrier
*barr
,
2478 bool wait_executing
)
2480 struct worker
*worker
= NULL
;
2481 struct global_cwq
*gcwq
;
2482 struct cpu_workqueue_struct
*cwq
;
2485 gcwq
= get_work_gcwq(work
);
2489 spin_lock_irq(&gcwq
->lock
);
2490 if (!list_empty(&work
->entry
)) {
2492 * See the comment near try_to_grab_pending()->smp_rmb().
2493 * If it was re-queued to a different gcwq under us, we
2494 * are not going to wait.
2497 cwq
= get_work_cwq(work
);
2498 if (unlikely(!cwq
|| gcwq
!= cwq
->pool
->gcwq
))
2500 } else if (wait_executing
) {
2501 worker
= find_worker_executing_work(gcwq
, work
);
2504 cwq
= worker
->current_cwq
;
2508 insert_wq_barrier(cwq
, barr
, work
, worker
);
2509 spin_unlock_irq(&gcwq
->lock
);
2512 * If @max_active is 1 or rescuer is in use, flushing another work
2513 * item on the same workqueue may lead to deadlock. Make sure the
2514 * flusher is not running on the same workqueue by verifying write
2517 if (cwq
->wq
->saved_max_active
== 1 || cwq
->wq
->flags
& WQ_RESCUER
)
2518 lock_map_acquire(&cwq
->wq
->lockdep_map
);
2520 lock_map_acquire_read(&cwq
->wq
->lockdep_map
);
2521 lock_map_release(&cwq
->wq
->lockdep_map
);
2525 spin_unlock_irq(&gcwq
->lock
);
2530 * flush_work - wait for a work to finish executing the last queueing instance
2531 * @work: the work to flush
2533 * Wait until @work has finished execution. This function considers
2534 * only the last queueing instance of @work. If @work has been
2535 * enqueued across different CPUs on a non-reentrant workqueue or on
2536 * multiple workqueues, @work might still be executing on return on
2537 * some of the CPUs from earlier queueing.
2539 * If @work was queued only on a non-reentrant, ordered or unbound
2540 * workqueue, @work is guaranteed to be idle on return if it hasn't
2541 * been requeued since flush started.
2544 * %true if flush_work() waited for the work to finish execution,
2545 * %false if it was already idle.
2547 bool flush_work(struct work_struct
*work
)
2549 struct wq_barrier barr
;
2551 lock_map_acquire(&work
->lockdep_map
);
2552 lock_map_release(&work
->lockdep_map
);
2554 if (start_flush_work(work
, &barr
, true)) {
2555 wait_for_completion(&barr
.done
);
2556 destroy_work_on_stack(&barr
.work
);
2561 EXPORT_SYMBOL_GPL(flush_work
);
2563 static bool wait_on_cpu_work(struct global_cwq
*gcwq
, struct work_struct
*work
)
2565 struct wq_barrier barr
;
2566 struct worker
*worker
;
2568 spin_lock_irq(&gcwq
->lock
);
2570 worker
= find_worker_executing_work(gcwq
, work
);
2571 if (unlikely(worker
))
2572 insert_wq_barrier(worker
->current_cwq
, &barr
, work
, worker
);
2574 spin_unlock_irq(&gcwq
->lock
);
2576 if (unlikely(worker
)) {
2577 wait_for_completion(&barr
.done
);
2578 destroy_work_on_stack(&barr
.work
);
2584 static bool wait_on_work(struct work_struct
*work
)
2591 lock_map_acquire(&work
->lockdep_map
);
2592 lock_map_release(&work
->lockdep_map
);
2594 for_each_gcwq_cpu(cpu
)
2595 ret
|= wait_on_cpu_work(get_gcwq(cpu
), work
);
2600 * flush_work_sync - wait until a work has finished execution
2601 * @work: the work to flush
2603 * Wait until @work has finished execution. On return, it's
2604 * guaranteed that all queueing instances of @work which happened
2605 * before this function is called are finished. In other words, if
2606 * @work hasn't been requeued since this function was called, @work is
2607 * guaranteed to be idle on return.
2610 * %true if flush_work_sync() waited for the work to finish execution,
2611 * %false if it was already idle.
2613 bool flush_work_sync(struct work_struct
*work
)
2615 struct wq_barrier barr
;
2616 bool pending
, waited
;
2618 /* we'll wait for executions separately, queue barr only if pending */
2619 pending
= start_flush_work(work
, &barr
, false);
2621 /* wait for executions to finish */
2622 waited
= wait_on_work(work
);
2624 /* wait for the pending one */
2626 wait_for_completion(&barr
.done
);
2627 destroy_work_on_stack(&barr
.work
);
2630 return pending
|| waited
;
2632 EXPORT_SYMBOL_GPL(flush_work_sync
);
2635 * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit,
2636 * so this work can't be re-armed in any way.
2638 static int try_to_grab_pending(struct work_struct
*work
)
2640 struct global_cwq
*gcwq
;
2643 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
)))
2647 * The queueing is in progress, or it is already queued. Try to
2648 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
2650 gcwq
= get_work_gcwq(work
);
2654 spin_lock_irq(&gcwq
->lock
);
2655 if (!list_empty(&work
->entry
)) {
2657 * This work is queued, but perhaps we locked the wrong gcwq.
2658 * In that case we must see the new value after rmb(), see
2659 * insert_work()->wmb().
2662 if (gcwq
== get_work_gcwq(work
)) {
2663 debug_work_deactivate(work
);
2664 list_del_init(&work
->entry
);
2665 cwq_dec_nr_in_flight(get_work_cwq(work
),
2666 get_work_color(work
),
2667 *work_data_bits(work
) & WORK_STRUCT_DELAYED
);
2671 spin_unlock_irq(&gcwq
->lock
);
2676 static bool __cancel_work_timer(struct work_struct
*work
,
2677 struct timer_list
* timer
)
2682 ret
= (timer
&& likely(del_timer(timer
)));
2684 ret
= try_to_grab_pending(work
);
2686 } while (unlikely(ret
< 0));
2688 clear_work_data(work
);
2693 * cancel_work_sync - cancel a work and wait for it to finish
2694 * @work: the work to cancel
2696 * Cancel @work and wait for its execution to finish. This function
2697 * can be used even if the work re-queues itself or migrates to
2698 * another workqueue. On return from this function, @work is
2699 * guaranteed to be not pending or executing on any CPU.
2701 * cancel_work_sync(&delayed_work->work) must not be used for
2702 * delayed_work's. Use cancel_delayed_work_sync() instead.
2704 * The caller must ensure that the workqueue on which @work was last
2705 * queued can't be destroyed before this function returns.
2708 * %true if @work was pending, %false otherwise.
2710 bool cancel_work_sync(struct work_struct
*work
)
2712 return __cancel_work_timer(work
, NULL
);
2714 EXPORT_SYMBOL_GPL(cancel_work_sync
);
2717 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2718 * @dwork: the delayed work to flush
2720 * Delayed timer is cancelled and the pending work is queued for
2721 * immediate execution. Like flush_work(), this function only
2722 * considers the last queueing instance of @dwork.
2725 * %true if flush_work() waited for the work to finish execution,
2726 * %false if it was already idle.
2728 bool flush_delayed_work(struct delayed_work
*dwork
)
2730 if (del_timer_sync(&dwork
->timer
))
2731 __queue_work(raw_smp_processor_id(),
2732 get_work_cwq(&dwork
->work
)->wq
, &dwork
->work
);
2733 return flush_work(&dwork
->work
);
2735 EXPORT_SYMBOL(flush_delayed_work
);
2738 * flush_delayed_work_sync - wait for a dwork to finish
2739 * @dwork: the delayed work to flush
2741 * Delayed timer is cancelled and the pending work is queued for
2742 * execution immediately. Other than timer handling, its behavior
2743 * is identical to flush_work_sync().
2746 * %true if flush_work_sync() waited for the work to finish execution,
2747 * %false if it was already idle.
2749 bool flush_delayed_work_sync(struct delayed_work
*dwork
)
2751 if (del_timer_sync(&dwork
->timer
))
2752 __queue_work(raw_smp_processor_id(),
2753 get_work_cwq(&dwork
->work
)->wq
, &dwork
->work
);
2754 return flush_work_sync(&dwork
->work
);
2756 EXPORT_SYMBOL(flush_delayed_work_sync
);
2759 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
2760 * @dwork: the delayed work cancel
2762 * This is cancel_work_sync() for delayed works.
2765 * %true if @dwork was pending, %false otherwise.
2767 bool cancel_delayed_work_sync(struct delayed_work
*dwork
)
2769 return __cancel_work_timer(&dwork
->work
, &dwork
->timer
);
2771 EXPORT_SYMBOL(cancel_delayed_work_sync
);
2774 * schedule_work - put work task in global workqueue
2775 * @work: job to be done
2777 * Returns zero if @work was already on the kernel-global workqueue and
2778 * non-zero otherwise.
2780 * This puts a job in the kernel-global workqueue if it was not already
2781 * queued and leaves it in the same position on the kernel-global
2782 * workqueue otherwise.
2784 int schedule_work(struct work_struct
*work
)
2786 return queue_work(system_wq
, work
);
2788 EXPORT_SYMBOL(schedule_work
);
2791 * schedule_work_on - put work task on a specific cpu
2792 * @cpu: cpu to put the work task on
2793 * @work: job to be done
2795 * This puts a job on a specific cpu
2797 int schedule_work_on(int cpu
, struct work_struct
*work
)
2799 return queue_work_on(cpu
, system_wq
, work
);
2801 EXPORT_SYMBOL(schedule_work_on
);
2804 * schedule_delayed_work - put work task in global workqueue after delay
2805 * @dwork: job to be done
2806 * @delay: number of jiffies to wait or 0 for immediate execution
2808 * After waiting for a given time this puts a job in the kernel-global
2811 int schedule_delayed_work(struct delayed_work
*dwork
,
2812 unsigned long delay
)
2814 return queue_delayed_work(system_wq
, dwork
, delay
);
2816 EXPORT_SYMBOL(schedule_delayed_work
);
2819 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
2821 * @dwork: job to be done
2822 * @delay: number of jiffies to wait
2824 * After waiting for a given time this puts a job in the kernel-global
2825 * workqueue on the specified CPU.
2827 int schedule_delayed_work_on(int cpu
,
2828 struct delayed_work
*dwork
, unsigned long delay
)
2830 return queue_delayed_work_on(cpu
, system_wq
, dwork
, delay
);
2832 EXPORT_SYMBOL(schedule_delayed_work_on
);
2835 * schedule_on_each_cpu - execute a function synchronously on each online CPU
2836 * @func: the function to call
2838 * schedule_on_each_cpu() executes @func on each online CPU using the
2839 * system workqueue and blocks until all CPUs have completed.
2840 * schedule_on_each_cpu() is very slow.
2843 * 0 on success, -errno on failure.
2845 int schedule_on_each_cpu(work_func_t func
)
2848 struct work_struct __percpu
*works
;
2850 works
= alloc_percpu(struct work_struct
);
2856 for_each_online_cpu(cpu
) {
2857 struct work_struct
*work
= per_cpu_ptr(works
, cpu
);
2859 INIT_WORK(work
, func
);
2860 schedule_work_on(cpu
, work
);
2863 for_each_online_cpu(cpu
)
2864 flush_work(per_cpu_ptr(works
, cpu
));
2872 * flush_scheduled_work - ensure that any scheduled work has run to completion.
2874 * Forces execution of the kernel-global workqueue and blocks until its
2877 * Think twice before calling this function! It's very easy to get into
2878 * trouble if you don't take great care. Either of the following situations
2879 * will lead to deadlock:
2881 * One of the work items currently on the workqueue needs to acquire
2882 * a lock held by your code or its caller.
2884 * Your code is running in the context of a work routine.
2886 * They will be detected by lockdep when they occur, but the first might not
2887 * occur very often. It depends on what work items are on the workqueue and
2888 * what locks they need, which you have no control over.
2890 * In most situations flushing the entire workqueue is overkill; you merely
2891 * need to know that a particular work item isn't queued and isn't running.
2892 * In such cases you should use cancel_delayed_work_sync() or
2893 * cancel_work_sync() instead.
2895 void flush_scheduled_work(void)
2897 flush_workqueue(system_wq
);
2899 EXPORT_SYMBOL(flush_scheduled_work
);
2902 * execute_in_process_context - reliably execute the routine with user context
2903 * @fn: the function to execute
2904 * @ew: guaranteed storage for the execute work structure (must
2905 * be available when the work executes)
2907 * Executes the function immediately if process context is available,
2908 * otherwise schedules the function for delayed execution.
2910 * Returns: 0 - function was executed
2911 * 1 - function was scheduled for execution
2913 int execute_in_process_context(work_func_t fn
, struct execute_work
*ew
)
2915 if (!in_interrupt()) {
2920 INIT_WORK(&ew
->work
, fn
);
2921 schedule_work(&ew
->work
);
2925 EXPORT_SYMBOL_GPL(execute_in_process_context
);
2927 int keventd_up(void)
2929 return system_wq
!= NULL
;
2932 static int alloc_cwqs(struct workqueue_struct
*wq
)
2935 * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS.
2936 * Make sure that the alignment isn't lower than that of
2937 * unsigned long long.
2939 const size_t size
= sizeof(struct cpu_workqueue_struct
);
2940 const size_t align
= max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS
,
2941 __alignof__(unsigned long long));
2943 if (!(wq
->flags
& WQ_UNBOUND
))
2944 wq
->cpu_wq
.pcpu
= __alloc_percpu(size
, align
);
2949 * Allocate enough room to align cwq and put an extra
2950 * pointer at the end pointing back to the originally
2951 * allocated pointer which will be used for free.
2953 ptr
= kzalloc(size
+ align
+ sizeof(void *), GFP_KERNEL
);
2955 wq
->cpu_wq
.single
= PTR_ALIGN(ptr
, align
);
2956 *(void **)(wq
->cpu_wq
.single
+ 1) = ptr
;
2960 /* just in case, make sure it's actually aligned */
2961 BUG_ON(!IS_ALIGNED(wq
->cpu_wq
.v
, align
));
2962 return wq
->cpu_wq
.v
? 0 : -ENOMEM
;
2965 static void free_cwqs(struct workqueue_struct
*wq
)
2967 if (!(wq
->flags
& WQ_UNBOUND
))
2968 free_percpu(wq
->cpu_wq
.pcpu
);
2969 else if (wq
->cpu_wq
.single
) {
2970 /* the pointer to free is stored right after the cwq */
2971 kfree(*(void **)(wq
->cpu_wq
.single
+ 1));
2975 static int wq_clamp_max_active(int max_active
, unsigned int flags
,
2978 int lim
= flags
& WQ_UNBOUND
? WQ_UNBOUND_MAX_ACTIVE
: WQ_MAX_ACTIVE
;
2980 if (max_active
< 1 || max_active
> lim
)
2981 printk(KERN_WARNING
"workqueue: max_active %d requested for %s "
2982 "is out of range, clamping between %d and %d\n",
2983 max_active
, name
, 1, lim
);
2985 return clamp_val(max_active
, 1, lim
);
2988 struct workqueue_struct
*__alloc_workqueue_key(const char *fmt
,
2991 struct lock_class_key
*key
,
2992 const char *lock_name
, ...)
2994 va_list args
, args1
;
2995 struct workqueue_struct
*wq
;
2999 /* determine namelen, allocate wq and format name */
3000 va_start(args
, lock_name
);
3001 va_copy(args1
, args
);
3002 namelen
= vsnprintf(NULL
, 0, fmt
, args
) + 1;
3004 wq
= kzalloc(sizeof(*wq
) + namelen
, GFP_KERNEL
);
3008 vsnprintf(wq
->name
, namelen
, fmt
, args1
);
3013 * Workqueues which may be used during memory reclaim should
3014 * have a rescuer to guarantee forward progress.
3016 if (flags
& WQ_MEM_RECLAIM
)
3017 flags
|= WQ_RESCUER
;
3019 max_active
= max_active
?: WQ_DFL_ACTIVE
;
3020 max_active
= wq_clamp_max_active(max_active
, flags
, wq
->name
);
3024 wq
->saved_max_active
= max_active
;
3025 mutex_init(&wq
->flush_mutex
);
3026 atomic_set(&wq
->nr_cwqs_to_flush
, 0);
3027 INIT_LIST_HEAD(&wq
->flusher_queue
);
3028 INIT_LIST_HEAD(&wq
->flusher_overflow
);
3030 lockdep_init_map(&wq
->lockdep_map
, lock_name
, key
, 0);
3031 INIT_LIST_HEAD(&wq
->list
);
3033 if (alloc_cwqs(wq
) < 0)
3036 for_each_cwq_cpu(cpu
, wq
) {
3037 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3038 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3040 BUG_ON((unsigned long)cwq
& WORK_STRUCT_FLAG_MASK
);
3041 cwq
->pool
= &gcwq
->pool
;
3043 cwq
->flush_color
= -1;
3044 cwq
->max_active
= max_active
;
3045 INIT_LIST_HEAD(&cwq
->delayed_works
);
3048 if (flags
& WQ_RESCUER
) {
3049 struct worker
*rescuer
;
3051 if (!alloc_mayday_mask(&wq
->mayday_mask
, GFP_KERNEL
))
3054 wq
->rescuer
= rescuer
= alloc_worker();
3058 rescuer
->task
= kthread_create(rescuer_thread
, wq
, "%s",
3060 if (IS_ERR(rescuer
->task
))
3063 rescuer
->task
->flags
|= PF_THREAD_BOUND
;
3064 wake_up_process(rescuer
->task
);
3068 * workqueue_lock protects global freeze state and workqueues
3069 * list. Grab it, set max_active accordingly and add the new
3070 * workqueue to workqueues list.
3072 spin_lock(&workqueue_lock
);
3074 if (workqueue_freezing
&& wq
->flags
& WQ_FREEZABLE
)
3075 for_each_cwq_cpu(cpu
, wq
)
3076 get_cwq(cpu
, wq
)->max_active
= 0;
3078 list_add(&wq
->list
, &workqueues
);
3080 spin_unlock(&workqueue_lock
);
3086 free_mayday_mask(wq
->mayday_mask
);
3092 EXPORT_SYMBOL_GPL(__alloc_workqueue_key
);
3095 * destroy_workqueue - safely terminate a workqueue
3096 * @wq: target workqueue
3098 * Safely destroy a workqueue. All work currently pending will be done first.
3100 void destroy_workqueue(struct workqueue_struct
*wq
)
3104 /* drain it before proceeding with destruction */
3105 drain_workqueue(wq
);
3108 * wq list is used to freeze wq, remove from list after
3109 * flushing is complete in case freeze races us.
3111 spin_lock(&workqueue_lock
);
3112 list_del(&wq
->list
);
3113 spin_unlock(&workqueue_lock
);
3116 for_each_cwq_cpu(cpu
, wq
) {
3117 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3120 for (i
= 0; i
< WORK_NR_COLORS
; i
++)
3121 BUG_ON(cwq
->nr_in_flight
[i
]);
3122 BUG_ON(cwq
->nr_active
);
3123 BUG_ON(!list_empty(&cwq
->delayed_works
));
3126 if (wq
->flags
& WQ_RESCUER
) {
3127 kthread_stop(wq
->rescuer
->task
);
3128 free_mayday_mask(wq
->mayday_mask
);
3135 EXPORT_SYMBOL_GPL(destroy_workqueue
);
3138 * workqueue_set_max_active - adjust max_active of a workqueue
3139 * @wq: target workqueue
3140 * @max_active: new max_active value.
3142 * Set max_active of @wq to @max_active.
3145 * Don't call from IRQ context.
3147 void workqueue_set_max_active(struct workqueue_struct
*wq
, int max_active
)
3151 max_active
= wq_clamp_max_active(max_active
, wq
->flags
, wq
->name
);
3153 spin_lock(&workqueue_lock
);
3155 wq
->saved_max_active
= max_active
;
3157 for_each_cwq_cpu(cpu
, wq
) {
3158 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3160 spin_lock_irq(&gcwq
->lock
);
3162 if (!(wq
->flags
& WQ_FREEZABLE
) ||
3163 !(gcwq
->flags
& GCWQ_FREEZING
))
3164 get_cwq(gcwq
->cpu
, wq
)->max_active
= max_active
;
3166 spin_unlock_irq(&gcwq
->lock
);
3169 spin_unlock(&workqueue_lock
);
3171 EXPORT_SYMBOL_GPL(workqueue_set_max_active
);
3174 * workqueue_congested - test whether a workqueue is congested
3175 * @cpu: CPU in question
3176 * @wq: target workqueue
3178 * Test whether @wq's cpu workqueue for @cpu is congested. There is
3179 * no synchronization around this function and the test result is
3180 * unreliable and only useful as advisory hints or for debugging.
3183 * %true if congested, %false otherwise.
3185 bool workqueue_congested(unsigned int cpu
, struct workqueue_struct
*wq
)
3187 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3189 return !list_empty(&cwq
->delayed_works
);
3191 EXPORT_SYMBOL_GPL(workqueue_congested
);
3194 * work_cpu - return the last known associated cpu for @work
3195 * @work: the work of interest
3198 * CPU number if @work was ever queued. WORK_CPU_NONE otherwise.
3200 unsigned int work_cpu(struct work_struct
*work
)
3202 struct global_cwq
*gcwq
= get_work_gcwq(work
);
3204 return gcwq
? gcwq
->cpu
: WORK_CPU_NONE
;
3206 EXPORT_SYMBOL_GPL(work_cpu
);
3209 * work_busy - test whether a work is currently pending or running
3210 * @work: the work to be tested
3212 * Test whether @work is currently pending or running. There is no
3213 * synchronization around this function and the test result is
3214 * unreliable and only useful as advisory hints or for debugging.
3215 * Especially for reentrant wqs, the pending state might hide the
3219 * OR'd bitmask of WORK_BUSY_* bits.
3221 unsigned int work_busy(struct work_struct
*work
)
3223 struct global_cwq
*gcwq
= get_work_gcwq(work
);
3224 unsigned long flags
;
3225 unsigned int ret
= 0;
3230 spin_lock_irqsave(&gcwq
->lock
, flags
);
3232 if (work_pending(work
))
3233 ret
|= WORK_BUSY_PENDING
;
3234 if (find_worker_executing_work(gcwq
, work
))
3235 ret
|= WORK_BUSY_RUNNING
;
3237 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
3241 EXPORT_SYMBOL_GPL(work_busy
);
3246 * There are two challenges in supporting CPU hotplug. Firstly, there
3247 * are a lot of assumptions on strong associations among work, cwq and
3248 * gcwq which make migrating pending and scheduled works very
3249 * difficult to implement without impacting hot paths. Secondly,
3250 * gcwqs serve mix of short, long and very long running works making
3251 * blocked draining impractical.
3253 * This is solved by allowing a gcwq to be detached from CPU, running
3254 * it with unbound (rogue) workers and allowing it to be reattached
3255 * later if the cpu comes back online. A separate thread is created
3256 * to govern a gcwq in such state and is called the trustee of the
3259 * Trustee states and their descriptions.
3261 * START Command state used on startup. On CPU_DOWN_PREPARE, a
3262 * new trustee is started with this state.
3264 * IN_CHARGE Once started, trustee will enter this state after
3265 * assuming the manager role and making all existing
3266 * workers rogue. DOWN_PREPARE waits for trustee to
3267 * enter this state. After reaching IN_CHARGE, trustee
3268 * tries to execute the pending worklist until it's empty
3269 * and the state is set to BUTCHER, or the state is set
3272 * BUTCHER Command state which is set by the cpu callback after
3273 * the cpu has went down. Once this state is set trustee
3274 * knows that there will be no new works on the worklist
3275 * and once the worklist is empty it can proceed to
3276 * killing idle workers.
3278 * RELEASE Command state which is set by the cpu callback if the
3279 * cpu down has been canceled or it has come online
3280 * again. After recognizing this state, trustee stops
3281 * trying to drain or butcher and clears ROGUE, rebinds
3282 * all remaining workers back to the cpu and releases
3285 * DONE Trustee will enter this state after BUTCHER or RELEASE
3288 * trustee CPU draining
3289 * took over down complete
3290 * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE
3292 * | CPU is back online v return workers |
3293 * ----------------> RELEASE --------------
3297 * trustee_wait_event_timeout - timed event wait for trustee
3298 * @cond: condition to wait for
3299 * @timeout: timeout in jiffies
3301 * wait_event_timeout() for trustee to use. Handles locking and
3302 * checks for RELEASE request.
3305 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3306 * multiple times. To be used by trustee.
3309 * Positive indicating left time if @cond is satisfied, 0 if timed
3310 * out, -1 if canceled.
3312 #define trustee_wait_event_timeout(cond, timeout) ({ \
3313 long __ret = (timeout); \
3314 while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \
3316 spin_unlock_irq(&gcwq->lock); \
3317 __wait_event_timeout(gcwq->trustee_wait, (cond) || \
3318 (gcwq->trustee_state == TRUSTEE_RELEASE), \
3320 spin_lock_irq(&gcwq->lock); \
3322 gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \
3326 * trustee_wait_event - event wait for trustee
3327 * @cond: condition to wait for
3329 * wait_event() for trustee to use. Automatically handles locking and
3330 * checks for CANCEL request.
3333 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3334 * multiple times. To be used by trustee.
3337 * 0 if @cond is satisfied, -1 if canceled.
3339 #define trustee_wait_event(cond) ({ \
3341 __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\
3342 __ret1 < 0 ? -1 : 0; \
3345 static int __cpuinit
trustee_thread(void *__gcwq
)
3347 struct global_cwq
*gcwq
= __gcwq
;
3348 struct worker
*worker
;
3349 struct work_struct
*work
;
3350 struct hlist_node
*pos
;
3354 BUG_ON(gcwq
->cpu
!= smp_processor_id());
3356 spin_lock_irq(&gcwq
->lock
);
3358 * Claim the manager position and make all workers rogue.
3359 * Trustee must be bound to the target cpu and can't be
3362 BUG_ON(gcwq
->cpu
!= smp_processor_id());
3363 rc
= trustee_wait_event(!(gcwq
->flags
& GCWQ_MANAGING_WORKERS
));
3366 gcwq
->flags
|= GCWQ_MANAGING_WORKERS
;
3368 list_for_each_entry(worker
, &gcwq
->pool
.idle_list
, entry
)
3369 worker
->flags
|= WORKER_ROGUE
;
3371 for_each_busy_worker(worker
, i
, pos
, gcwq
)
3372 worker
->flags
|= WORKER_ROGUE
;
3375 * Call schedule() so that we cross rq->lock and thus can
3376 * guarantee sched callbacks see the rogue flag. This is
3377 * necessary as scheduler callbacks may be invoked from other
3380 spin_unlock_irq(&gcwq
->lock
);
3382 spin_lock_irq(&gcwq
->lock
);
3385 * Sched callbacks are disabled now. Zap nr_running. After
3386 * this, nr_running stays zero and need_more_worker() and
3387 * keep_working() are always true as long as the worklist is
3390 atomic_set(get_pool_nr_running(&gcwq
->pool
), 0);
3392 spin_unlock_irq(&gcwq
->lock
);
3393 del_timer_sync(&gcwq
->pool
.idle_timer
);
3394 spin_lock_irq(&gcwq
->lock
);
3397 * We're now in charge. Notify and proceed to drain. We need
3398 * to keep the gcwq running during the whole CPU down
3399 * procedure as other cpu hotunplug callbacks may need to
3400 * flush currently running tasks.
3402 gcwq
->trustee_state
= TRUSTEE_IN_CHARGE
;
3403 wake_up_all(&gcwq
->trustee_wait
);
3406 * The original cpu is in the process of dying and may go away
3407 * anytime now. When that happens, we and all workers would
3408 * be migrated to other cpus. Try draining any left work. We
3409 * want to get it over with ASAP - spam rescuers, wake up as
3410 * many idlers as necessary and create new ones till the
3411 * worklist is empty. Note that if the gcwq is frozen, there
3412 * may be frozen works in freezable cwqs. Don't declare
3413 * completion while frozen.
3415 while (gcwq
->pool
.nr_workers
!= gcwq
->pool
.nr_idle
||
3416 gcwq
->flags
& GCWQ_FREEZING
||
3417 gcwq
->trustee_state
== TRUSTEE_IN_CHARGE
) {
3420 list_for_each_entry(work
, &gcwq
->pool
.worklist
, entry
) {
3425 list_for_each_entry(worker
, &gcwq
->pool
.idle_list
, entry
) {
3428 wake_up_process(worker
->task
);
3431 if (need_to_create_worker(&gcwq
->pool
)) {
3432 spin_unlock_irq(&gcwq
->lock
);
3433 worker
= create_worker(&gcwq
->pool
, false);
3434 spin_lock_irq(&gcwq
->lock
);
3436 worker
->flags
|= WORKER_ROGUE
;
3437 start_worker(worker
);
3441 /* give a breather */
3442 if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN
) < 0)
3447 * Either all works have been scheduled and cpu is down, or
3448 * cpu down has already been canceled. Wait for and butcher
3449 * all workers till we're canceled.
3452 rc
= trustee_wait_event(!list_empty(&gcwq
->pool
.idle_list
));
3453 while (!list_empty(&gcwq
->pool
.idle_list
))
3454 destroy_worker(list_first_entry(&gcwq
->pool
.idle_list
,
3455 struct worker
, entry
));
3456 } while (gcwq
->pool
.nr_workers
&& rc
>= 0);
3459 * At this point, either draining has completed and no worker
3460 * is left, or cpu down has been canceled or the cpu is being
3461 * brought back up. There shouldn't be any idle one left.
3462 * Tell the remaining busy ones to rebind once it finishes the
3463 * currently scheduled works by scheduling the rebind_work.
3465 WARN_ON(!list_empty(&gcwq
->pool
.idle_list
));
3467 for_each_busy_worker(worker
, i
, pos
, gcwq
) {
3468 struct work_struct
*rebind_work
= &worker
->rebind_work
;
3471 * Rebind_work may race with future cpu hotplug
3472 * operations. Use a separate flag to mark that
3473 * rebinding is scheduled.
3475 worker
->flags
|= WORKER_REBIND
;
3476 worker
->flags
&= ~WORKER_ROGUE
;
3478 /* queue rebind_work, wq doesn't matter, use the default one */
3479 if (test_and_set_bit(WORK_STRUCT_PENDING_BIT
,
3480 work_data_bits(rebind_work
)))
3483 debug_work_activate(rebind_work
);
3484 insert_work(get_cwq(gcwq
->cpu
, system_wq
), rebind_work
,
3485 worker
->scheduled
.next
,
3486 work_color_to_flags(WORK_NO_COLOR
));
3489 /* relinquish manager role */
3490 gcwq
->flags
&= ~GCWQ_MANAGING_WORKERS
;
3492 /* notify completion */
3493 gcwq
->trustee
= NULL
;
3494 gcwq
->trustee_state
= TRUSTEE_DONE
;
3495 wake_up_all(&gcwq
->trustee_wait
);
3496 spin_unlock_irq(&gcwq
->lock
);
3501 * wait_trustee_state - wait for trustee to enter the specified state
3502 * @gcwq: gcwq the trustee of interest belongs to
3503 * @state: target state to wait for
3505 * Wait for the trustee to reach @state. DONE is already matched.
3508 * spin_lock_irq(gcwq->lock) which may be released and regrabbed
3509 * multiple times. To be used by cpu_callback.
3511 static void __cpuinit
wait_trustee_state(struct global_cwq
*gcwq
, int state
)
3512 __releases(&gcwq
->lock
)
3513 __acquires(&gcwq
->lock
)
3515 if (!(gcwq
->trustee_state
== state
||
3516 gcwq
->trustee_state
== TRUSTEE_DONE
)) {
3517 spin_unlock_irq(&gcwq
->lock
);
3518 __wait_event(gcwq
->trustee_wait
,
3519 gcwq
->trustee_state
== state
||
3520 gcwq
->trustee_state
== TRUSTEE_DONE
);
3521 spin_lock_irq(&gcwq
->lock
);
3525 static int __devinit
workqueue_cpu_callback(struct notifier_block
*nfb
,
3526 unsigned long action
,
3529 unsigned int cpu
= (unsigned long)hcpu
;
3530 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3531 struct task_struct
*new_trustee
= NULL
;
3532 struct worker
*uninitialized_var(new_worker
);
3533 unsigned long flags
;
3535 action
&= ~CPU_TASKS_FROZEN
;
3538 case CPU_DOWN_PREPARE
:
3539 new_trustee
= kthread_create(trustee_thread
, gcwq
,
3540 "workqueue_trustee/%d\n", cpu
);
3541 if (IS_ERR(new_trustee
))
3542 return notifier_from_errno(PTR_ERR(new_trustee
));
3543 kthread_bind(new_trustee
, cpu
);
3545 case CPU_UP_PREPARE
:
3546 BUG_ON(gcwq
->pool
.first_idle
);
3547 new_worker
= create_worker(&gcwq
->pool
, false);
3550 kthread_stop(new_trustee
);
3555 /* some are called w/ irq disabled, don't disturb irq status */
3556 spin_lock_irqsave(&gcwq
->lock
, flags
);
3559 case CPU_DOWN_PREPARE
:
3560 /* initialize trustee and tell it to acquire the gcwq */
3561 BUG_ON(gcwq
->trustee
|| gcwq
->trustee_state
!= TRUSTEE_DONE
);
3562 gcwq
->trustee
= new_trustee
;
3563 gcwq
->trustee_state
= TRUSTEE_START
;
3564 wake_up_process(gcwq
->trustee
);
3565 wait_trustee_state(gcwq
, TRUSTEE_IN_CHARGE
);
3567 case CPU_UP_PREPARE
:
3568 BUG_ON(gcwq
->pool
.first_idle
);
3569 gcwq
->pool
.first_idle
= new_worker
;
3574 * Before this, the trustee and all workers except for
3575 * the ones which are still executing works from
3576 * before the last CPU down must be on the cpu. After
3577 * this, they'll all be diasporas.
3579 gcwq
->flags
|= GCWQ_DISASSOCIATED
;
3583 gcwq
->trustee_state
= TRUSTEE_BUTCHER
;
3585 case CPU_UP_CANCELED
:
3586 destroy_worker(gcwq
->pool
.first_idle
);
3587 gcwq
->pool
.first_idle
= NULL
;
3590 case CPU_DOWN_FAILED
:
3592 gcwq
->flags
&= ~GCWQ_DISASSOCIATED
;
3593 if (gcwq
->trustee_state
!= TRUSTEE_DONE
) {
3594 gcwq
->trustee_state
= TRUSTEE_RELEASE
;
3595 wake_up_process(gcwq
->trustee
);
3596 wait_trustee_state(gcwq
, TRUSTEE_DONE
);
3600 * Trustee is done and there might be no worker left.
3601 * Put the first_idle in and request a real manager to
3604 spin_unlock_irq(&gcwq
->lock
);
3605 kthread_bind(gcwq
->pool
.first_idle
->task
, cpu
);
3606 spin_lock_irq(&gcwq
->lock
);
3607 gcwq
->flags
|= GCWQ_MANAGE_WORKERS
;
3608 start_worker(gcwq
->pool
.first_idle
);
3609 gcwq
->pool
.first_idle
= NULL
;
3613 spin_unlock_irqrestore(&gcwq
->lock
, flags
);
3615 return notifier_from_errno(0);
3620 struct work_for_cpu
{
3621 struct completion completion
;
3627 static int do_work_for_cpu(void *_wfc
)
3629 struct work_for_cpu
*wfc
= _wfc
;
3630 wfc
->ret
= wfc
->fn(wfc
->arg
);
3631 complete(&wfc
->completion
);
3636 * work_on_cpu - run a function in user context on a particular cpu
3637 * @cpu: the cpu to run on
3638 * @fn: the function to run
3639 * @arg: the function arg
3641 * This will return the value @fn returns.
3642 * It is up to the caller to ensure that the cpu doesn't go offline.
3643 * The caller must not hold any locks which would prevent @fn from completing.
3645 long work_on_cpu(unsigned int cpu
, long (*fn
)(void *), void *arg
)
3647 struct task_struct
*sub_thread
;
3648 struct work_for_cpu wfc
= {
3649 .completion
= COMPLETION_INITIALIZER_ONSTACK(wfc
.completion
),
3654 sub_thread
= kthread_create(do_work_for_cpu
, &wfc
, "work_for_cpu");
3655 if (IS_ERR(sub_thread
))
3656 return PTR_ERR(sub_thread
);
3657 kthread_bind(sub_thread
, cpu
);
3658 wake_up_process(sub_thread
);
3659 wait_for_completion(&wfc
.completion
);
3662 EXPORT_SYMBOL_GPL(work_on_cpu
);
3663 #endif /* CONFIG_SMP */
3665 #ifdef CONFIG_FREEZER
3668 * freeze_workqueues_begin - begin freezing workqueues
3670 * Start freezing workqueues. After this function returns, all freezable
3671 * workqueues will queue new works to their frozen_works list instead of
3675 * Grabs and releases workqueue_lock and gcwq->lock's.
3677 void freeze_workqueues_begin(void)
3681 spin_lock(&workqueue_lock
);
3683 BUG_ON(workqueue_freezing
);
3684 workqueue_freezing
= true;
3686 for_each_gcwq_cpu(cpu
) {
3687 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3688 struct workqueue_struct
*wq
;
3690 spin_lock_irq(&gcwq
->lock
);
3692 BUG_ON(gcwq
->flags
& GCWQ_FREEZING
);
3693 gcwq
->flags
|= GCWQ_FREEZING
;
3695 list_for_each_entry(wq
, &workqueues
, list
) {
3696 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3698 if (cwq
&& wq
->flags
& WQ_FREEZABLE
)
3699 cwq
->max_active
= 0;
3702 spin_unlock_irq(&gcwq
->lock
);
3705 spin_unlock(&workqueue_lock
);
3709 * freeze_workqueues_busy - are freezable workqueues still busy?
3711 * Check whether freezing is complete. This function must be called
3712 * between freeze_workqueues_begin() and thaw_workqueues().
3715 * Grabs and releases workqueue_lock.
3718 * %true if some freezable workqueues are still busy. %false if freezing
3721 bool freeze_workqueues_busy(void)
3726 spin_lock(&workqueue_lock
);
3728 BUG_ON(!workqueue_freezing
);
3730 for_each_gcwq_cpu(cpu
) {
3731 struct workqueue_struct
*wq
;
3733 * nr_active is monotonically decreasing. It's safe
3734 * to peek without lock.
3736 list_for_each_entry(wq
, &workqueues
, list
) {
3737 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3739 if (!cwq
|| !(wq
->flags
& WQ_FREEZABLE
))
3742 BUG_ON(cwq
->nr_active
< 0);
3743 if (cwq
->nr_active
) {
3750 spin_unlock(&workqueue_lock
);
3755 * thaw_workqueues - thaw workqueues
3757 * Thaw workqueues. Normal queueing is restored and all collected
3758 * frozen works are transferred to their respective gcwq worklists.
3761 * Grabs and releases workqueue_lock and gcwq->lock's.
3763 void thaw_workqueues(void)
3767 spin_lock(&workqueue_lock
);
3769 if (!workqueue_freezing
)
3772 for_each_gcwq_cpu(cpu
) {
3773 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3774 struct workqueue_struct
*wq
;
3776 spin_lock_irq(&gcwq
->lock
);
3778 BUG_ON(!(gcwq
->flags
& GCWQ_FREEZING
));
3779 gcwq
->flags
&= ~GCWQ_FREEZING
;
3781 list_for_each_entry(wq
, &workqueues
, list
) {
3782 struct cpu_workqueue_struct
*cwq
= get_cwq(cpu
, wq
);
3784 if (!cwq
|| !(wq
->flags
& WQ_FREEZABLE
))
3787 /* restore max_active and repopulate worklist */
3788 cwq
->max_active
= wq
->saved_max_active
;
3790 while (!list_empty(&cwq
->delayed_works
) &&
3791 cwq
->nr_active
< cwq
->max_active
)
3792 cwq_activate_first_delayed(cwq
);
3795 wake_up_worker(&gcwq
->pool
);
3797 spin_unlock_irq(&gcwq
->lock
);
3800 workqueue_freezing
= false;
3802 spin_unlock(&workqueue_lock
);
3804 #endif /* CONFIG_FREEZER */
3806 static int __init
init_workqueues(void)
3811 cpu_notifier(workqueue_cpu_callback
, CPU_PRI_WORKQUEUE
);
3813 /* initialize gcwqs */
3814 for_each_gcwq_cpu(cpu
) {
3815 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3817 spin_lock_init(&gcwq
->lock
);
3818 gcwq
->pool
.gcwq
= gcwq
;
3819 INIT_LIST_HEAD(&gcwq
->pool
.worklist
);
3821 gcwq
->flags
|= GCWQ_DISASSOCIATED
;
3823 INIT_LIST_HEAD(&gcwq
->pool
.idle_list
);
3824 for (i
= 0; i
< BUSY_WORKER_HASH_SIZE
; i
++)
3825 INIT_HLIST_HEAD(&gcwq
->busy_hash
[i
]);
3827 init_timer_deferrable(&gcwq
->pool
.idle_timer
);
3828 gcwq
->pool
.idle_timer
.function
= idle_worker_timeout
;
3829 gcwq
->pool
.idle_timer
.data
= (unsigned long)&gcwq
->pool
;
3831 setup_timer(&gcwq
->pool
.mayday_timer
, gcwq_mayday_timeout
,
3832 (unsigned long)&gcwq
->pool
);
3834 ida_init(&gcwq
->pool
.worker_ida
);
3836 gcwq
->trustee_state
= TRUSTEE_DONE
;
3837 init_waitqueue_head(&gcwq
->trustee_wait
);
3840 /* create the initial worker */
3841 for_each_online_gcwq_cpu(cpu
) {
3842 struct global_cwq
*gcwq
= get_gcwq(cpu
);
3843 struct worker
*worker
;
3845 if (cpu
!= WORK_CPU_UNBOUND
)
3846 gcwq
->flags
&= ~GCWQ_DISASSOCIATED
;
3847 worker
= create_worker(&gcwq
->pool
, true);
3849 spin_lock_irq(&gcwq
->lock
);
3850 start_worker(worker
);
3851 spin_unlock_irq(&gcwq
->lock
);
3854 system_wq
= alloc_workqueue("events", 0, 0);
3855 system_long_wq
= alloc_workqueue("events_long", 0, 0);
3856 system_nrt_wq
= alloc_workqueue("events_nrt", WQ_NON_REENTRANT
, 0);
3857 system_unbound_wq
= alloc_workqueue("events_unbound", WQ_UNBOUND
,
3858 WQ_UNBOUND_MAX_ACTIVE
);
3859 system_freezable_wq
= alloc_workqueue("events_freezable",
3861 system_nrt_freezable_wq
= alloc_workqueue("events_nrt_freezable",
3862 WQ_NON_REENTRANT
| WQ_FREEZABLE
, 0);
3863 BUG_ON(!system_wq
|| !system_long_wq
|| !system_nrt_wq
||
3864 !system_unbound_wq
|| !system_freezable_wq
||
3865 !system_nrt_freezable_wq
);
3868 early_initcall(init_workqueues
);