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>
44 #include <linux/jhash.h>
45 #include <linux/hashtable.h>
46 #include <linux/rculist.h>
48 #include "workqueue_internal.h"
54 * A bound pool is either associated or disassociated with its CPU.
55 * While associated (!DISASSOCIATED), all workers are bound to the
56 * CPU and none has %WORKER_UNBOUND set and concurrency management
59 * While DISASSOCIATED, the cpu may be offline and all workers have
60 * %WORKER_UNBOUND set and concurrency management disabled, and may
61 * be executing on any CPU. The pool behaves as an unbound one.
63 * Note that DISASSOCIATED can be flipped only while holding
64 * assoc_mutex to avoid changing binding state while
65 * create_worker() is in progress.
67 POOL_MANAGE_WORKERS
= 1 << 0, /* need to manage workers */
68 POOL_DISASSOCIATED
= 1 << 2, /* cpu can't serve workers */
69 POOL_FREEZING
= 1 << 3, /* freeze in progress */
72 WORKER_STARTED
= 1 << 0, /* started */
73 WORKER_DIE
= 1 << 1, /* die die die */
74 WORKER_IDLE
= 1 << 2, /* is idle */
75 WORKER_PREP
= 1 << 3, /* preparing to run works */
76 WORKER_CPU_INTENSIVE
= 1 << 6, /* cpu intensive */
77 WORKER_UNBOUND
= 1 << 7, /* worker is unbound */
79 WORKER_NOT_RUNNING
= WORKER_PREP
| WORKER_UNBOUND
|
82 NR_STD_WORKER_POOLS
= 2, /* # standard pools per cpu */
84 UNBOUND_POOL_HASH_ORDER
= 6, /* hashed by pool->attrs */
85 BUSY_WORKER_HASH_ORDER
= 6, /* 64 pointers */
87 MAX_IDLE_WORKERS_RATIO
= 4, /* 1/4 of busy can be idle */
88 IDLE_WORKER_TIMEOUT
= 300 * HZ
, /* keep idle ones for 5 mins */
90 MAYDAY_INITIAL_TIMEOUT
= HZ
/ 100 >= 2 ? HZ
/ 100 : 2,
91 /* call for help after 10ms
93 MAYDAY_INTERVAL
= HZ
/ 10, /* and then every 100ms */
94 CREATE_COOLDOWN
= HZ
, /* time to breath after fail */
97 * Rescue workers are used only on emergencies and shared by
100 RESCUER_NICE_LEVEL
= -20,
101 HIGHPRI_NICE_LEVEL
= -20,
105 * Structure fields follow one of the following exclusion rules.
107 * I: Modifiable by initialization/destruction paths and read-only for
110 * P: Preemption protected. Disabling preemption is enough and should
111 * only be modified and accessed from the local cpu.
113 * L: pool->lock protected. Access with pool->lock held.
115 * X: During normal operation, modification requires pool->lock and should
116 * be done only from local cpu. Either disabling preemption on local
117 * cpu or grabbing pool->lock is enough for read access. If
118 * POOL_DISASSOCIATED is set, it's identical to L.
120 * F: wq->flush_mutex protected.
122 * W: workqueue_lock protected.
124 * R: workqueue_lock protected for writes. Sched-RCU protected for reads.
127 /* struct worker is defined in workqueue_internal.h */
130 spinlock_t lock
; /* the pool lock */
131 int cpu
; /* I: the associated cpu */
132 int id
; /* I: pool ID */
133 unsigned int flags
; /* X: flags */
135 struct list_head worklist
; /* L: list of pending works */
136 int nr_workers
; /* L: total number of workers */
138 /* nr_idle includes the ones off idle_list for rebinding */
139 int nr_idle
; /* L: currently idle ones */
141 struct list_head idle_list
; /* X: list of idle workers */
142 struct timer_list idle_timer
; /* L: worker idle timeout */
143 struct timer_list mayday_timer
; /* L: SOS timer for workers */
145 /* workers are chained either in busy_hash or idle_list */
146 DECLARE_HASHTABLE(busy_hash
, BUSY_WORKER_HASH_ORDER
);
147 /* L: hash of busy workers */
149 struct mutex manager_arb
; /* manager arbitration */
150 struct mutex assoc_mutex
; /* protect POOL_DISASSOCIATED */
151 struct ida worker_ida
; /* L: for worker IDs */
153 struct workqueue_attrs
*attrs
; /* I: worker attributes */
154 struct hlist_node hash_node
; /* R: unbound_pool_hash node */
155 int refcnt
; /* refcnt for unbound pools */
158 * The current concurrency level. As it's likely to be accessed
159 * from other CPUs during try_to_wake_up(), put it in a separate
162 atomic_t nr_running ____cacheline_aligned_in_smp
;
165 * Destruction of pool is sched-RCU protected to allow dereferences
166 * from get_work_pool().
169 } ____cacheline_aligned_in_smp
;
172 * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
173 * of work_struct->data are used for flags and the remaining high bits
174 * point to the pwq; thus, pwqs need to be aligned at two's power of the
175 * number of flag bits.
177 struct pool_workqueue
{
178 struct worker_pool
*pool
; /* I: the associated pool */
179 struct workqueue_struct
*wq
; /* I: the owning workqueue */
180 int work_color
; /* L: current color */
181 int flush_color
; /* L: flushing color */
182 int nr_in_flight
[WORK_NR_COLORS
];
183 /* L: nr of in_flight works */
184 int nr_active
; /* L: nr of active works */
185 int max_active
; /* L: max active works */
186 struct list_head delayed_works
; /* L: delayed works */
187 struct list_head pwqs_node
; /* R: node on wq->pwqs */
188 struct list_head mayday_node
; /* W: node on wq->maydays */
189 } __aligned(1 << WORK_STRUCT_FLAG_BITS
);
192 * Structure used to wait for workqueue flush.
195 struct list_head list
; /* F: list of flushers */
196 int flush_color
; /* F: flush color waiting for */
197 struct completion done
; /* flush completion */
201 * The externally visible workqueue abstraction is an array of
202 * per-CPU workqueues:
204 struct workqueue_struct
{
205 unsigned int flags
; /* W: WQ_* flags */
206 struct pool_workqueue __percpu
*cpu_pwqs
; /* I: per-cpu pwq's */
207 struct list_head pwqs
; /* R: all pwqs of this wq */
208 struct list_head list
; /* W: list of all workqueues */
210 struct mutex flush_mutex
; /* protects wq flushing */
211 int work_color
; /* F: current work color */
212 int flush_color
; /* F: current flush color */
213 atomic_t nr_pwqs_to_flush
; /* flush in progress */
214 struct wq_flusher
*first_flusher
; /* F: first flusher */
215 struct list_head flusher_queue
; /* F: flush waiters */
216 struct list_head flusher_overflow
; /* F: flush overflow list */
218 struct list_head maydays
; /* W: pwqs requesting rescue */
219 struct worker
*rescuer
; /* I: rescue worker */
221 int nr_drainers
; /* W: drain in progress */
222 int saved_max_active
; /* W: saved pwq max_active */
223 #ifdef CONFIG_LOCKDEP
224 struct lockdep_map lockdep_map
;
226 char name
[]; /* I: workqueue name */
229 static struct kmem_cache
*pwq_cache
;
231 /* hash of all unbound pools keyed by pool->attrs */
232 static DEFINE_HASHTABLE(unbound_pool_hash
, UNBOUND_POOL_HASH_ORDER
);
234 static struct workqueue_attrs
*unbound_std_wq_attrs
[NR_STD_WORKER_POOLS
];
236 struct workqueue_struct
*system_wq __read_mostly
;
237 EXPORT_SYMBOL_GPL(system_wq
);
238 struct workqueue_struct
*system_highpri_wq __read_mostly
;
239 EXPORT_SYMBOL_GPL(system_highpri_wq
);
240 struct workqueue_struct
*system_long_wq __read_mostly
;
241 EXPORT_SYMBOL_GPL(system_long_wq
);
242 struct workqueue_struct
*system_unbound_wq __read_mostly
;
243 EXPORT_SYMBOL_GPL(system_unbound_wq
);
244 struct workqueue_struct
*system_freezable_wq __read_mostly
;
245 EXPORT_SYMBOL_GPL(system_freezable_wq
);
247 #define CREATE_TRACE_POINTS
248 #include <trace/events/workqueue.h>
250 #define assert_rcu_or_wq_lock() \
251 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
252 lockdep_is_held(&workqueue_lock), \
253 "sched RCU or workqueue lock should be held")
255 #define for_each_cpu_worker_pool(pool, cpu) \
256 for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
257 (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
260 #define for_each_busy_worker(worker, i, pool) \
261 hash_for_each(pool->busy_hash, i, worker, hentry)
264 * for_each_pool - iterate through all worker_pools in the system
265 * @pool: iteration cursor
266 * @id: integer used for iteration
268 * This must be called either with workqueue_lock held or sched RCU read
269 * locked. If the pool needs to be used beyond the locking in effect, the
270 * caller is responsible for guaranteeing that the pool stays online.
272 * The if/else clause exists only for the lockdep assertion and can be
275 #define for_each_pool(pool, id) \
276 idr_for_each_entry(&worker_pool_idr, pool, id) \
277 if (({ assert_rcu_or_wq_lock(); false; })) { } \
281 * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
282 * @pwq: iteration cursor
283 * @wq: the target workqueue
285 * This must be called either with workqueue_lock held or sched RCU read
286 * locked. If the pwq needs to be used beyond the locking in effect, the
287 * caller is responsible for guaranteeing that the pwq stays online.
289 * The if/else clause exists only for the lockdep assertion and can be
292 #define for_each_pwq(pwq, wq) \
293 list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
294 if (({ assert_rcu_or_wq_lock(); false; })) { } \
297 #ifdef CONFIG_DEBUG_OBJECTS_WORK
299 static struct debug_obj_descr work_debug_descr
;
301 static void *work_debug_hint(void *addr
)
303 return ((struct work_struct
*) addr
)->func
;
307 * fixup_init is called when:
308 * - an active object is initialized
310 static int work_fixup_init(void *addr
, enum debug_obj_state state
)
312 struct work_struct
*work
= addr
;
315 case ODEBUG_STATE_ACTIVE
:
316 cancel_work_sync(work
);
317 debug_object_init(work
, &work_debug_descr
);
325 * fixup_activate is called when:
326 * - an active object is activated
327 * - an unknown object is activated (might be a statically initialized object)
329 static int work_fixup_activate(void *addr
, enum debug_obj_state state
)
331 struct work_struct
*work
= addr
;
335 case ODEBUG_STATE_NOTAVAILABLE
:
337 * This is not really a fixup. The work struct was
338 * statically initialized. We just make sure that it
339 * is tracked in the object tracker.
341 if (test_bit(WORK_STRUCT_STATIC_BIT
, work_data_bits(work
))) {
342 debug_object_init(work
, &work_debug_descr
);
343 debug_object_activate(work
, &work_debug_descr
);
349 case ODEBUG_STATE_ACTIVE
:
358 * fixup_free is called when:
359 * - an active object is freed
361 static int work_fixup_free(void *addr
, enum debug_obj_state state
)
363 struct work_struct
*work
= addr
;
366 case ODEBUG_STATE_ACTIVE
:
367 cancel_work_sync(work
);
368 debug_object_free(work
, &work_debug_descr
);
375 static struct debug_obj_descr work_debug_descr
= {
376 .name
= "work_struct",
377 .debug_hint
= work_debug_hint
,
378 .fixup_init
= work_fixup_init
,
379 .fixup_activate
= work_fixup_activate
,
380 .fixup_free
= work_fixup_free
,
383 static inline void debug_work_activate(struct work_struct
*work
)
385 debug_object_activate(work
, &work_debug_descr
);
388 static inline void debug_work_deactivate(struct work_struct
*work
)
390 debug_object_deactivate(work
, &work_debug_descr
);
393 void __init_work(struct work_struct
*work
, int onstack
)
396 debug_object_init_on_stack(work
, &work_debug_descr
);
398 debug_object_init(work
, &work_debug_descr
);
400 EXPORT_SYMBOL_GPL(__init_work
);
402 void destroy_work_on_stack(struct work_struct
*work
)
404 debug_object_free(work
, &work_debug_descr
);
406 EXPORT_SYMBOL_GPL(destroy_work_on_stack
);
409 static inline void debug_work_activate(struct work_struct
*work
) { }
410 static inline void debug_work_deactivate(struct work_struct
*work
) { }
413 /* Serializes the accesses to the list of workqueues. */
414 static DEFINE_SPINLOCK(workqueue_lock
);
415 static LIST_HEAD(workqueues
);
416 static bool workqueue_freezing
; /* W: have wqs started freezing? */
419 * The CPU and unbound standard worker pools. The unbound ones have
420 * POOL_DISASSOCIATED set, and their workers have WORKER_UNBOUND set.
422 static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool
[NR_STD_WORKER_POOLS
],
426 * idr of all pools. Modifications are protected by workqueue_lock. Read
427 * accesses are protected by sched-RCU protected.
429 static DEFINE_IDR(worker_pool_idr
);
431 static int worker_thread(void *__worker
);
433 /* allocate ID and assign it to @pool */
434 static int worker_pool_assign_id(struct worker_pool
*pool
)
439 if (!idr_pre_get(&worker_pool_idr
, GFP_KERNEL
))
442 spin_lock_irq(&workqueue_lock
);
443 ret
= idr_get_new(&worker_pool_idr
, pool
, &pool
->id
);
444 spin_unlock_irq(&workqueue_lock
);
445 } while (ret
== -EAGAIN
);
451 * first_pwq - return the first pool_workqueue of the specified workqueue
452 * @wq: the target workqueue
454 * This must be called either with workqueue_lock held or sched RCU read
455 * locked. If the pwq needs to be used beyond the locking in effect, the
456 * caller is responsible for guaranteeing that the pwq stays online.
458 static struct pool_workqueue
*first_pwq(struct workqueue_struct
*wq
)
460 assert_rcu_or_wq_lock();
461 return list_first_or_null_rcu(&wq
->pwqs
, struct pool_workqueue
,
465 static unsigned int work_color_to_flags(int color
)
467 return color
<< WORK_STRUCT_COLOR_SHIFT
;
470 static int get_work_color(struct work_struct
*work
)
472 return (*work_data_bits(work
) >> WORK_STRUCT_COLOR_SHIFT
) &
473 ((1 << WORK_STRUCT_COLOR_BITS
) - 1);
476 static int work_next_color(int color
)
478 return (color
+ 1) % WORK_NR_COLORS
;
482 * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
483 * contain the pointer to the queued pwq. Once execution starts, the flag
484 * is cleared and the high bits contain OFFQ flags and pool ID.
486 * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
487 * and clear_work_data() can be used to set the pwq, pool or clear
488 * work->data. These functions should only be called while the work is
489 * owned - ie. while the PENDING bit is set.
491 * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
492 * corresponding to a work. Pool is available once the work has been
493 * queued anywhere after initialization until it is sync canceled. pwq is
494 * available only while the work item is queued.
496 * %WORK_OFFQ_CANCELING is used to mark a work item which is being
497 * canceled. While being canceled, a work item may have its PENDING set
498 * but stay off timer and worklist for arbitrarily long and nobody should
499 * try to steal the PENDING bit.
501 static inline void set_work_data(struct work_struct
*work
, unsigned long data
,
504 WARN_ON_ONCE(!work_pending(work
));
505 atomic_long_set(&work
->data
, data
| flags
| work_static(work
));
508 static void set_work_pwq(struct work_struct
*work
, struct pool_workqueue
*pwq
,
509 unsigned long extra_flags
)
511 set_work_data(work
, (unsigned long)pwq
,
512 WORK_STRUCT_PENDING
| WORK_STRUCT_PWQ
| extra_flags
);
515 static void set_work_pool_and_keep_pending(struct work_struct
*work
,
518 set_work_data(work
, (unsigned long)pool_id
<< WORK_OFFQ_POOL_SHIFT
,
519 WORK_STRUCT_PENDING
);
522 static void set_work_pool_and_clear_pending(struct work_struct
*work
,
526 * The following wmb is paired with the implied mb in
527 * test_and_set_bit(PENDING) and ensures all updates to @work made
528 * here are visible to and precede any updates by the next PENDING
532 set_work_data(work
, (unsigned long)pool_id
<< WORK_OFFQ_POOL_SHIFT
, 0);
535 static void clear_work_data(struct work_struct
*work
)
537 smp_wmb(); /* see set_work_pool_and_clear_pending() */
538 set_work_data(work
, WORK_STRUCT_NO_POOL
, 0);
541 static struct pool_workqueue
*get_work_pwq(struct work_struct
*work
)
543 unsigned long data
= atomic_long_read(&work
->data
);
545 if (data
& WORK_STRUCT_PWQ
)
546 return (void *)(data
& WORK_STRUCT_WQ_DATA_MASK
);
552 * get_work_pool - return the worker_pool a given work was associated with
553 * @work: the work item of interest
555 * Return the worker_pool @work was last associated with. %NULL if none.
557 * Pools are created and destroyed under workqueue_lock, and allows read
558 * access under sched-RCU read lock. As such, this function should be
559 * called under workqueue_lock or with preemption disabled.
561 * All fields of the returned pool are accessible as long as the above
562 * mentioned locking is in effect. If the returned pool needs to be used
563 * beyond the critical section, the caller is responsible for ensuring the
564 * returned pool is and stays online.
566 static struct worker_pool
*get_work_pool(struct work_struct
*work
)
568 unsigned long data
= atomic_long_read(&work
->data
);
571 assert_rcu_or_wq_lock();
573 if (data
& WORK_STRUCT_PWQ
)
574 return ((struct pool_workqueue
*)
575 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
;
577 pool_id
= data
>> WORK_OFFQ_POOL_SHIFT
;
578 if (pool_id
== WORK_OFFQ_POOL_NONE
)
581 return idr_find(&worker_pool_idr
, pool_id
);
585 * get_work_pool_id - return the worker pool ID a given work is associated with
586 * @work: the work item of interest
588 * Return the worker_pool ID @work was last associated with.
589 * %WORK_OFFQ_POOL_NONE if none.
591 static int get_work_pool_id(struct work_struct
*work
)
593 unsigned long data
= atomic_long_read(&work
->data
);
595 if (data
& WORK_STRUCT_PWQ
)
596 return ((struct pool_workqueue
*)
597 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
->id
;
599 return data
>> WORK_OFFQ_POOL_SHIFT
;
602 static void mark_work_canceling(struct work_struct
*work
)
604 unsigned long pool_id
= get_work_pool_id(work
);
606 pool_id
<<= WORK_OFFQ_POOL_SHIFT
;
607 set_work_data(work
, pool_id
| WORK_OFFQ_CANCELING
, WORK_STRUCT_PENDING
);
610 static bool work_is_canceling(struct work_struct
*work
)
612 unsigned long data
= atomic_long_read(&work
->data
);
614 return !(data
& WORK_STRUCT_PWQ
) && (data
& WORK_OFFQ_CANCELING
);
618 * Policy functions. These define the policies on how the global worker
619 * pools are managed. Unless noted otherwise, these functions assume that
620 * they're being called with pool->lock held.
623 static bool __need_more_worker(struct worker_pool
*pool
)
625 return !atomic_read(&pool
->nr_running
);
629 * Need to wake up a worker? Called from anything but currently
632 * Note that, because unbound workers never contribute to nr_running, this
633 * function will always return %true for unbound pools as long as the
634 * worklist isn't empty.
636 static bool need_more_worker(struct worker_pool
*pool
)
638 return !list_empty(&pool
->worklist
) && __need_more_worker(pool
);
641 /* Can I start working? Called from busy but !running workers. */
642 static bool may_start_working(struct worker_pool
*pool
)
644 return pool
->nr_idle
;
647 /* Do I need to keep working? Called from currently running workers. */
648 static bool keep_working(struct worker_pool
*pool
)
650 return !list_empty(&pool
->worklist
) &&
651 atomic_read(&pool
->nr_running
) <= 1;
654 /* Do we need a new worker? Called from manager. */
655 static bool need_to_create_worker(struct worker_pool
*pool
)
657 return need_more_worker(pool
) && !may_start_working(pool
);
660 /* Do I need to be the manager? */
661 static bool need_to_manage_workers(struct worker_pool
*pool
)
663 return need_to_create_worker(pool
) ||
664 (pool
->flags
& POOL_MANAGE_WORKERS
);
667 /* Do we have too many workers and should some go away? */
668 static bool too_many_workers(struct worker_pool
*pool
)
670 bool managing
= mutex_is_locked(&pool
->manager_arb
);
671 int nr_idle
= pool
->nr_idle
+ managing
; /* manager is considered idle */
672 int nr_busy
= pool
->nr_workers
- nr_idle
;
675 * nr_idle and idle_list may disagree if idle rebinding is in
676 * progress. Never return %true if idle_list is empty.
678 if (list_empty(&pool
->idle_list
))
681 return nr_idle
> 2 && (nr_idle
- 2) * MAX_IDLE_WORKERS_RATIO
>= nr_busy
;
688 /* Return the first worker. Safe with preemption disabled */
689 static struct worker
*first_worker(struct worker_pool
*pool
)
691 if (unlikely(list_empty(&pool
->idle_list
)))
694 return list_first_entry(&pool
->idle_list
, struct worker
, entry
);
698 * wake_up_worker - wake up an idle worker
699 * @pool: worker pool to wake worker from
701 * Wake up the first idle worker of @pool.
704 * spin_lock_irq(pool->lock).
706 static void wake_up_worker(struct worker_pool
*pool
)
708 struct worker
*worker
= first_worker(pool
);
711 wake_up_process(worker
->task
);
715 * wq_worker_waking_up - a worker is waking up
716 * @task: task waking up
717 * @cpu: CPU @task is waking up to
719 * This function is called during try_to_wake_up() when a worker is
723 * spin_lock_irq(rq->lock)
725 void wq_worker_waking_up(struct task_struct
*task
, int cpu
)
727 struct worker
*worker
= kthread_data(task
);
729 if (!(worker
->flags
& WORKER_NOT_RUNNING
)) {
730 WARN_ON_ONCE(worker
->pool
->cpu
!= cpu
);
731 atomic_inc(&worker
->pool
->nr_running
);
736 * wq_worker_sleeping - a worker is going to sleep
737 * @task: task going to sleep
738 * @cpu: CPU in question, must be the current CPU number
740 * This function is called during schedule() when a busy worker is
741 * going to sleep. Worker on the same cpu can be woken up by
742 * returning pointer to its task.
745 * spin_lock_irq(rq->lock)
748 * Worker task on @cpu to wake up, %NULL if none.
750 struct task_struct
*wq_worker_sleeping(struct task_struct
*task
, int cpu
)
752 struct worker
*worker
= kthread_data(task
), *to_wakeup
= NULL
;
753 struct worker_pool
*pool
;
756 * Rescuers, which may not have all the fields set up like normal
757 * workers, also reach here, let's not access anything before
758 * checking NOT_RUNNING.
760 if (worker
->flags
& WORKER_NOT_RUNNING
)
765 /* this can only happen on the local cpu */
766 if (WARN_ON_ONCE(cpu
!= raw_smp_processor_id()))
770 * The counterpart of the following dec_and_test, implied mb,
771 * worklist not empty test sequence is in insert_work().
772 * Please read comment there.
774 * NOT_RUNNING is clear. This means that we're bound to and
775 * running on the local cpu w/ rq lock held and preemption
776 * disabled, which in turn means that none else could be
777 * manipulating idle_list, so dereferencing idle_list without pool
780 if (atomic_dec_and_test(&pool
->nr_running
) &&
781 !list_empty(&pool
->worklist
))
782 to_wakeup
= first_worker(pool
);
783 return to_wakeup
? to_wakeup
->task
: NULL
;
787 * worker_set_flags - set worker flags and adjust nr_running accordingly
789 * @flags: flags to set
790 * @wakeup: wakeup an idle worker if necessary
792 * Set @flags in @worker->flags and adjust nr_running accordingly. If
793 * nr_running becomes zero and @wakeup is %true, an idle worker is
797 * spin_lock_irq(pool->lock)
799 static inline void worker_set_flags(struct worker
*worker
, unsigned int flags
,
802 struct worker_pool
*pool
= worker
->pool
;
804 WARN_ON_ONCE(worker
->task
!= current
);
807 * If transitioning into NOT_RUNNING, adjust nr_running and
808 * wake up an idle worker as necessary if requested by
811 if ((flags
& WORKER_NOT_RUNNING
) &&
812 !(worker
->flags
& WORKER_NOT_RUNNING
)) {
814 if (atomic_dec_and_test(&pool
->nr_running
) &&
815 !list_empty(&pool
->worklist
))
816 wake_up_worker(pool
);
818 atomic_dec(&pool
->nr_running
);
821 worker
->flags
|= flags
;
825 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
827 * @flags: flags to clear
829 * Clear @flags in @worker->flags and adjust nr_running accordingly.
832 * spin_lock_irq(pool->lock)
834 static inline void worker_clr_flags(struct worker
*worker
, unsigned int flags
)
836 struct worker_pool
*pool
= worker
->pool
;
837 unsigned int oflags
= worker
->flags
;
839 WARN_ON_ONCE(worker
->task
!= current
);
841 worker
->flags
&= ~flags
;
844 * If transitioning out of NOT_RUNNING, increment nr_running. Note
845 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
846 * of multiple flags, not a single flag.
848 if ((flags
& WORKER_NOT_RUNNING
) && (oflags
& WORKER_NOT_RUNNING
))
849 if (!(worker
->flags
& WORKER_NOT_RUNNING
))
850 atomic_inc(&pool
->nr_running
);
854 * find_worker_executing_work - find worker which is executing a work
855 * @pool: pool of interest
856 * @work: work to find worker for
858 * Find a worker which is executing @work on @pool by searching
859 * @pool->busy_hash which is keyed by the address of @work. For a worker
860 * to match, its current execution should match the address of @work and
861 * its work function. This is to avoid unwanted dependency between
862 * unrelated work executions through a work item being recycled while still
865 * This is a bit tricky. A work item may be freed once its execution
866 * starts and nothing prevents the freed area from being recycled for
867 * another work item. If the same work item address ends up being reused
868 * before the original execution finishes, workqueue will identify the
869 * recycled work item as currently executing and make it wait until the
870 * current execution finishes, introducing an unwanted dependency.
872 * This function checks the work item address, work function and workqueue
873 * to avoid false positives. Note that this isn't complete as one may
874 * construct a work function which can introduce dependency onto itself
875 * through a recycled work item. Well, if somebody wants to shoot oneself
876 * in the foot that badly, there's only so much we can do, and if such
877 * deadlock actually occurs, it should be easy to locate the culprit work
881 * spin_lock_irq(pool->lock).
884 * Pointer to worker which is executing @work if found, NULL
887 static struct worker
*find_worker_executing_work(struct worker_pool
*pool
,
888 struct work_struct
*work
)
890 struct worker
*worker
;
892 hash_for_each_possible(pool
->busy_hash
, worker
, hentry
,
894 if (worker
->current_work
== work
&&
895 worker
->current_func
== work
->func
)
902 * move_linked_works - move linked works to a list
903 * @work: start of series of works to be scheduled
904 * @head: target list to append @work to
905 * @nextp: out paramter for nested worklist walking
907 * Schedule linked works starting from @work to @head. Work series to
908 * be scheduled starts at @work and includes any consecutive work with
909 * WORK_STRUCT_LINKED set in its predecessor.
911 * If @nextp is not NULL, it's updated to point to the next work of
912 * the last scheduled work. This allows move_linked_works() to be
913 * nested inside outer list_for_each_entry_safe().
916 * spin_lock_irq(pool->lock).
918 static void move_linked_works(struct work_struct
*work
, struct list_head
*head
,
919 struct work_struct
**nextp
)
921 struct work_struct
*n
;
924 * Linked worklist will always end before the end of the list,
925 * use NULL for list head.
927 list_for_each_entry_safe_from(work
, n
, NULL
, entry
) {
928 list_move_tail(&work
->entry
, head
);
929 if (!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))
934 * If we're already inside safe list traversal and have moved
935 * multiple works to the scheduled queue, the next position
936 * needs to be updated.
942 static void pwq_activate_delayed_work(struct work_struct
*work
)
944 struct pool_workqueue
*pwq
= get_work_pwq(work
);
946 trace_workqueue_activate_work(work
);
947 move_linked_works(work
, &pwq
->pool
->worklist
, NULL
);
948 __clear_bit(WORK_STRUCT_DELAYED_BIT
, work_data_bits(work
));
952 static void pwq_activate_first_delayed(struct pool_workqueue
*pwq
)
954 struct work_struct
*work
= list_first_entry(&pwq
->delayed_works
,
955 struct work_struct
, entry
);
957 pwq_activate_delayed_work(work
);
961 * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
962 * @pwq: pwq of interest
963 * @color: color of work which left the queue
965 * A work either has completed or is removed from pending queue,
966 * decrement nr_in_flight of its pwq and handle workqueue flushing.
969 * spin_lock_irq(pool->lock).
971 static void pwq_dec_nr_in_flight(struct pool_workqueue
*pwq
, int color
)
973 /* ignore uncolored works */
974 if (color
== WORK_NO_COLOR
)
977 pwq
->nr_in_flight
[color
]--;
980 if (!list_empty(&pwq
->delayed_works
)) {
981 /* one down, submit a delayed one */
982 if (pwq
->nr_active
< pwq
->max_active
)
983 pwq_activate_first_delayed(pwq
);
986 /* is flush in progress and are we at the flushing tip? */
987 if (likely(pwq
->flush_color
!= color
))
990 /* are there still in-flight works? */
991 if (pwq
->nr_in_flight
[color
])
994 /* this pwq is done, clear flush_color */
995 pwq
->flush_color
= -1;
998 * If this was the last pwq, wake up the first flusher. It
999 * will handle the rest.
1001 if (atomic_dec_and_test(&pwq
->wq
->nr_pwqs_to_flush
))
1002 complete(&pwq
->wq
->first_flusher
->done
);
1006 * try_to_grab_pending - steal work item from worklist and disable irq
1007 * @work: work item to steal
1008 * @is_dwork: @work is a delayed_work
1009 * @flags: place to store irq state
1011 * Try to grab PENDING bit of @work. This function can handle @work in any
1012 * stable state - idle, on timer or on worklist. Return values are
1014 * 1 if @work was pending and we successfully stole PENDING
1015 * 0 if @work was idle and we claimed PENDING
1016 * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
1017 * -ENOENT if someone else is canceling @work, this state may persist
1018 * for arbitrarily long
1020 * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
1021 * interrupted while holding PENDING and @work off queue, irq must be
1022 * disabled on entry. This, combined with delayed_work->timer being
1023 * irqsafe, ensures that we return -EAGAIN for finite short period of time.
1025 * On successful return, >= 0, irq is disabled and the caller is
1026 * responsible for releasing it using local_irq_restore(*@flags).
1028 * This function is safe to call from any context including IRQ handler.
1030 static int try_to_grab_pending(struct work_struct
*work
, bool is_dwork
,
1031 unsigned long *flags
)
1033 struct worker_pool
*pool
;
1034 struct pool_workqueue
*pwq
;
1036 local_irq_save(*flags
);
1038 /* try to steal the timer if it exists */
1040 struct delayed_work
*dwork
= to_delayed_work(work
);
1043 * dwork->timer is irqsafe. If del_timer() fails, it's
1044 * guaranteed that the timer is not queued anywhere and not
1045 * running on the local CPU.
1047 if (likely(del_timer(&dwork
->timer
)))
1051 /* try to claim PENDING the normal way */
1052 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
)))
1056 * The queueing is in progress, or it is already queued. Try to
1057 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
1059 pool
= get_work_pool(work
);
1063 spin_lock(&pool
->lock
);
1065 * work->data is guaranteed to point to pwq only while the work
1066 * item is queued on pwq->wq, and both updating work->data to point
1067 * to pwq on queueing and to pool on dequeueing are done under
1068 * pwq->pool->lock. This in turn guarantees that, if work->data
1069 * points to pwq which is associated with a locked pool, the work
1070 * item is currently queued on that pool.
1072 pwq
= get_work_pwq(work
);
1073 if (pwq
&& pwq
->pool
== pool
) {
1074 debug_work_deactivate(work
);
1077 * A delayed work item cannot be grabbed directly because
1078 * it might have linked NO_COLOR work items which, if left
1079 * on the delayed_list, will confuse pwq->nr_active
1080 * management later on and cause stall. Make sure the work
1081 * item is activated before grabbing.
1083 if (*work_data_bits(work
) & WORK_STRUCT_DELAYED
)
1084 pwq_activate_delayed_work(work
);
1086 list_del_init(&work
->entry
);
1087 pwq_dec_nr_in_flight(get_work_pwq(work
), get_work_color(work
));
1089 /* work->data points to pwq iff queued, point to pool */
1090 set_work_pool_and_keep_pending(work
, pool
->id
);
1092 spin_unlock(&pool
->lock
);
1095 spin_unlock(&pool
->lock
);
1097 local_irq_restore(*flags
);
1098 if (work_is_canceling(work
))
1105 * insert_work - insert a work into a pool
1106 * @pwq: pwq @work belongs to
1107 * @work: work to insert
1108 * @head: insertion point
1109 * @extra_flags: extra WORK_STRUCT_* flags to set
1111 * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
1112 * work_struct flags.
1115 * spin_lock_irq(pool->lock).
1117 static void insert_work(struct pool_workqueue
*pwq
, struct work_struct
*work
,
1118 struct list_head
*head
, unsigned int extra_flags
)
1120 struct worker_pool
*pool
= pwq
->pool
;
1122 /* we own @work, set data and link */
1123 set_work_pwq(work
, pwq
, extra_flags
);
1124 list_add_tail(&work
->entry
, head
);
1127 * Ensure either worker_sched_deactivated() sees the above
1128 * list_add_tail() or we see zero nr_running to avoid workers
1129 * lying around lazily while there are works to be processed.
1133 if (__need_more_worker(pool
))
1134 wake_up_worker(pool
);
1138 * Test whether @work is being queued from another work executing on the
1141 static bool is_chained_work(struct workqueue_struct
*wq
)
1143 struct worker
*worker
;
1145 worker
= current_wq_worker();
1147 * Return %true iff I'm a worker execuing a work item on @wq. If
1148 * I'm @worker, it's safe to dereference it without locking.
1150 return worker
&& worker
->current_pwq
->wq
== wq
;
1153 static void __queue_work(int cpu
, struct workqueue_struct
*wq
,
1154 struct work_struct
*work
)
1156 struct pool_workqueue
*pwq
;
1157 struct list_head
*worklist
;
1158 unsigned int work_flags
;
1159 unsigned int req_cpu
= cpu
;
1162 * While a work item is PENDING && off queue, a task trying to
1163 * steal the PENDING will busy-loop waiting for it to either get
1164 * queued or lose PENDING. Grabbing PENDING and queueing should
1165 * happen with IRQ disabled.
1167 WARN_ON_ONCE(!irqs_disabled());
1169 debug_work_activate(work
);
1171 /* if dying, only works from the same workqueue are allowed */
1172 if (unlikely(wq
->flags
& WQ_DRAINING
) &&
1173 WARN_ON_ONCE(!is_chained_work(wq
)))
1176 /* determine the pwq to use */
1177 if (!(wq
->flags
& WQ_UNBOUND
)) {
1178 struct worker_pool
*last_pool
;
1180 if (cpu
== WORK_CPU_UNBOUND
)
1181 cpu
= raw_smp_processor_id();
1184 * It's multi cpu. If @work was previously on a different
1185 * cpu, it might still be running there, in which case the
1186 * work needs to be queued on that cpu to guarantee
1189 pwq
= per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
1190 last_pool
= get_work_pool(work
);
1192 if (last_pool
&& last_pool
!= pwq
->pool
) {
1193 struct worker
*worker
;
1195 spin_lock(&last_pool
->lock
);
1197 worker
= find_worker_executing_work(last_pool
, work
);
1199 if (worker
&& worker
->current_pwq
->wq
== wq
) {
1200 pwq
= per_cpu_ptr(wq
->cpu_pwqs
, last_pool
->cpu
);
1202 /* meh... not running there, queue here */
1203 spin_unlock(&last_pool
->lock
);
1204 spin_lock(&pwq
->pool
->lock
);
1207 spin_lock(&pwq
->pool
->lock
);
1210 pwq
= first_pwq(wq
);
1211 spin_lock(&pwq
->pool
->lock
);
1214 /* pwq determined, queue */
1215 trace_workqueue_queue_work(req_cpu
, pwq
, work
);
1217 if (WARN_ON(!list_empty(&work
->entry
))) {
1218 spin_unlock(&pwq
->pool
->lock
);
1222 pwq
->nr_in_flight
[pwq
->work_color
]++;
1223 work_flags
= work_color_to_flags(pwq
->work_color
);
1225 if (likely(pwq
->nr_active
< pwq
->max_active
)) {
1226 trace_workqueue_activate_work(work
);
1228 worklist
= &pwq
->pool
->worklist
;
1230 work_flags
|= WORK_STRUCT_DELAYED
;
1231 worklist
= &pwq
->delayed_works
;
1234 insert_work(pwq
, work
, worklist
, work_flags
);
1236 spin_unlock(&pwq
->pool
->lock
);
1240 * queue_work_on - queue work on specific cpu
1241 * @cpu: CPU number to execute work on
1242 * @wq: workqueue to use
1243 * @work: work to queue
1245 * Returns %false if @work was already on a queue, %true otherwise.
1247 * We queue the work to a specific CPU, the caller must ensure it
1250 bool queue_work_on(int cpu
, struct workqueue_struct
*wq
,
1251 struct work_struct
*work
)
1254 unsigned long flags
;
1256 local_irq_save(flags
);
1258 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1259 __queue_work(cpu
, wq
, work
);
1263 local_irq_restore(flags
);
1266 EXPORT_SYMBOL_GPL(queue_work_on
);
1269 * queue_work - queue work on a workqueue
1270 * @wq: workqueue to use
1271 * @work: work to queue
1273 * Returns %false if @work was already on a queue, %true otherwise.
1275 * We queue the work to the CPU on which it was submitted, but if the CPU dies
1276 * it can be processed by another CPU.
1278 bool queue_work(struct workqueue_struct
*wq
, struct work_struct
*work
)
1280 return queue_work_on(WORK_CPU_UNBOUND
, wq
, work
);
1282 EXPORT_SYMBOL_GPL(queue_work
);
1284 void delayed_work_timer_fn(unsigned long __data
)
1286 struct delayed_work
*dwork
= (struct delayed_work
*)__data
;
1288 /* should have been called from irqsafe timer with irq already off */
1289 __queue_work(dwork
->cpu
, dwork
->wq
, &dwork
->work
);
1291 EXPORT_SYMBOL(delayed_work_timer_fn
);
1293 static void __queue_delayed_work(int cpu
, struct workqueue_struct
*wq
,
1294 struct delayed_work
*dwork
, unsigned long delay
)
1296 struct timer_list
*timer
= &dwork
->timer
;
1297 struct work_struct
*work
= &dwork
->work
;
1299 WARN_ON_ONCE(timer
->function
!= delayed_work_timer_fn
||
1300 timer
->data
!= (unsigned long)dwork
);
1301 WARN_ON_ONCE(timer_pending(timer
));
1302 WARN_ON_ONCE(!list_empty(&work
->entry
));
1305 * If @delay is 0, queue @dwork->work immediately. This is for
1306 * both optimization and correctness. The earliest @timer can
1307 * expire is on the closest next tick and delayed_work users depend
1308 * on that there's no such delay when @delay is 0.
1311 __queue_work(cpu
, wq
, &dwork
->work
);
1315 timer_stats_timer_set_start_info(&dwork
->timer
);
1319 timer
->expires
= jiffies
+ delay
;
1321 if (unlikely(cpu
!= WORK_CPU_UNBOUND
))
1322 add_timer_on(timer
, cpu
);
1328 * queue_delayed_work_on - queue work on specific CPU after delay
1329 * @cpu: CPU number to execute work on
1330 * @wq: workqueue to use
1331 * @dwork: work to queue
1332 * @delay: number of jiffies to wait before queueing
1334 * Returns %false if @work was already on a queue, %true otherwise. If
1335 * @delay is zero and @dwork is idle, it will be scheduled for immediate
1338 bool queue_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1339 struct delayed_work
*dwork
, unsigned long delay
)
1341 struct work_struct
*work
= &dwork
->work
;
1343 unsigned long flags
;
1345 /* read the comment in __queue_work() */
1346 local_irq_save(flags
);
1348 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1349 __queue_delayed_work(cpu
, wq
, dwork
, delay
);
1353 local_irq_restore(flags
);
1356 EXPORT_SYMBOL_GPL(queue_delayed_work_on
);
1359 * queue_delayed_work - queue work on a workqueue after delay
1360 * @wq: workqueue to use
1361 * @dwork: delayable work to queue
1362 * @delay: number of jiffies to wait before queueing
1364 * Equivalent to queue_delayed_work_on() but tries to use the local CPU.
1366 bool queue_delayed_work(struct workqueue_struct
*wq
,
1367 struct delayed_work
*dwork
, unsigned long delay
)
1369 return queue_delayed_work_on(WORK_CPU_UNBOUND
, wq
, dwork
, delay
);
1371 EXPORT_SYMBOL_GPL(queue_delayed_work
);
1374 * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
1375 * @cpu: CPU number to execute work on
1376 * @wq: workqueue to use
1377 * @dwork: work to queue
1378 * @delay: number of jiffies to wait before queueing
1380 * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
1381 * modify @dwork's timer so that it expires after @delay. If @delay is
1382 * zero, @work is guaranteed to be scheduled immediately regardless of its
1385 * Returns %false if @dwork was idle and queued, %true if @dwork was
1386 * pending and its timer was modified.
1388 * This function is safe to call from any context including IRQ handler.
1389 * See try_to_grab_pending() for details.
1391 bool mod_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1392 struct delayed_work
*dwork
, unsigned long delay
)
1394 unsigned long flags
;
1398 ret
= try_to_grab_pending(&dwork
->work
, true, &flags
);
1399 } while (unlikely(ret
== -EAGAIN
));
1401 if (likely(ret
>= 0)) {
1402 __queue_delayed_work(cpu
, wq
, dwork
, delay
);
1403 local_irq_restore(flags
);
1406 /* -ENOENT from try_to_grab_pending() becomes %true */
1409 EXPORT_SYMBOL_GPL(mod_delayed_work_on
);
1412 * mod_delayed_work - modify delay of or queue a delayed work
1413 * @wq: workqueue to use
1414 * @dwork: work to queue
1415 * @delay: number of jiffies to wait before queueing
1417 * mod_delayed_work_on() on local CPU.
1419 bool mod_delayed_work(struct workqueue_struct
*wq
, struct delayed_work
*dwork
,
1420 unsigned long delay
)
1422 return mod_delayed_work_on(WORK_CPU_UNBOUND
, wq
, dwork
, delay
);
1424 EXPORT_SYMBOL_GPL(mod_delayed_work
);
1427 * worker_enter_idle - enter idle state
1428 * @worker: worker which is entering idle state
1430 * @worker is entering idle state. Update stats and idle timer if
1434 * spin_lock_irq(pool->lock).
1436 static void worker_enter_idle(struct worker
*worker
)
1438 struct worker_pool
*pool
= worker
->pool
;
1440 if (WARN_ON_ONCE(worker
->flags
& WORKER_IDLE
) ||
1441 WARN_ON_ONCE(!list_empty(&worker
->entry
) &&
1442 (worker
->hentry
.next
|| worker
->hentry
.pprev
)))
1445 /* can't use worker_set_flags(), also called from start_worker() */
1446 worker
->flags
|= WORKER_IDLE
;
1448 worker
->last_active
= jiffies
;
1450 /* idle_list is LIFO */
1451 list_add(&worker
->entry
, &pool
->idle_list
);
1453 if (too_many_workers(pool
) && !timer_pending(&pool
->idle_timer
))
1454 mod_timer(&pool
->idle_timer
, jiffies
+ IDLE_WORKER_TIMEOUT
);
1457 * Sanity check nr_running. Because wq_unbind_fn() releases
1458 * pool->lock between setting %WORKER_UNBOUND and zapping
1459 * nr_running, the warning may trigger spuriously. Check iff
1460 * unbind is not in progress.
1462 WARN_ON_ONCE(!(pool
->flags
& POOL_DISASSOCIATED
) &&
1463 pool
->nr_workers
== pool
->nr_idle
&&
1464 atomic_read(&pool
->nr_running
));
1468 * worker_leave_idle - leave idle state
1469 * @worker: worker which is leaving idle state
1471 * @worker is leaving idle state. Update stats.
1474 * spin_lock_irq(pool->lock).
1476 static void worker_leave_idle(struct worker
*worker
)
1478 struct worker_pool
*pool
= worker
->pool
;
1480 if (WARN_ON_ONCE(!(worker
->flags
& WORKER_IDLE
)))
1482 worker_clr_flags(worker
, WORKER_IDLE
);
1484 list_del_init(&worker
->entry
);
1488 * worker_maybe_bind_and_lock - try to bind %current to worker_pool and lock it
1489 * @pool: target worker_pool
1491 * Bind %current to the cpu of @pool if it is associated and lock @pool.
1493 * Works which are scheduled while the cpu is online must at least be
1494 * scheduled to a worker which is bound to the cpu so that if they are
1495 * flushed from cpu callbacks while cpu is going down, they are
1496 * guaranteed to execute on the cpu.
1498 * This function is to be used by unbound workers and rescuers to bind
1499 * themselves to the target cpu and may race with cpu going down or
1500 * coming online. kthread_bind() can't be used because it may put the
1501 * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
1502 * verbatim as it's best effort and blocking and pool may be
1503 * [dis]associated in the meantime.
1505 * This function tries set_cpus_allowed() and locks pool and verifies the
1506 * binding against %POOL_DISASSOCIATED which is set during
1507 * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker
1508 * enters idle state or fetches works without dropping lock, it can
1509 * guarantee the scheduling requirement described in the first paragraph.
1512 * Might sleep. Called without any lock but returns with pool->lock
1516 * %true if the associated pool is online (@worker is successfully
1517 * bound), %false if offline.
1519 static bool worker_maybe_bind_and_lock(struct worker_pool
*pool
)
1520 __acquires(&pool
->lock
)
1524 * The following call may fail, succeed or succeed
1525 * without actually migrating the task to the cpu if
1526 * it races with cpu hotunplug operation. Verify
1527 * against POOL_DISASSOCIATED.
1529 if (!(pool
->flags
& POOL_DISASSOCIATED
))
1530 set_cpus_allowed_ptr(current
, pool
->attrs
->cpumask
);
1532 spin_lock_irq(&pool
->lock
);
1533 if (pool
->flags
& POOL_DISASSOCIATED
)
1535 if (task_cpu(current
) == pool
->cpu
&&
1536 cpumask_equal(¤t
->cpus_allowed
, pool
->attrs
->cpumask
))
1538 spin_unlock_irq(&pool
->lock
);
1541 * We've raced with CPU hot[un]plug. Give it a breather
1542 * and retry migration. cond_resched() is required here;
1543 * otherwise, we might deadlock against cpu_stop trying to
1544 * bring down the CPU on non-preemptive kernel.
1552 * Rebind an idle @worker to its CPU. worker_thread() will test
1553 * list_empty(@worker->entry) before leaving idle and call this function.
1555 static void idle_worker_rebind(struct worker
*worker
)
1557 /* CPU may go down again inbetween, clear UNBOUND only on success */
1558 if (worker_maybe_bind_and_lock(worker
->pool
))
1559 worker_clr_flags(worker
, WORKER_UNBOUND
);
1561 /* rebind complete, become available again */
1562 list_add(&worker
->entry
, &worker
->pool
->idle_list
);
1563 spin_unlock_irq(&worker
->pool
->lock
);
1567 * Function for @worker->rebind.work used to rebind unbound busy workers to
1568 * the associated cpu which is coming back online. This is scheduled by
1569 * cpu up but can race with other cpu hotplug operations and may be
1570 * executed twice without intervening cpu down.
1572 static void busy_worker_rebind_fn(struct work_struct
*work
)
1574 struct worker
*worker
= container_of(work
, struct worker
, rebind_work
);
1576 if (worker_maybe_bind_and_lock(worker
->pool
))
1577 worker_clr_flags(worker
, WORKER_UNBOUND
);
1579 spin_unlock_irq(&worker
->pool
->lock
);
1583 * rebind_workers - rebind all workers of a pool to the associated CPU
1584 * @pool: pool of interest
1586 * @pool->cpu is coming online. Rebind all workers to the CPU. Rebinding
1587 * is different for idle and busy ones.
1589 * Idle ones will be removed from the idle_list and woken up. They will
1590 * add themselves back after completing rebind. This ensures that the
1591 * idle_list doesn't contain any unbound workers when re-bound busy workers
1592 * try to perform local wake-ups for concurrency management.
1594 * Busy workers can rebind after they finish their current work items.
1595 * Queueing the rebind work item at the head of the scheduled list is
1596 * enough. Note that nr_running will be properly bumped as busy workers
1599 * On return, all non-manager workers are scheduled for rebind - see
1600 * manage_workers() for the manager special case. Any idle worker
1601 * including the manager will not appear on @idle_list until rebind is
1602 * complete, making local wake-ups safe.
1604 static void rebind_workers(struct worker_pool
*pool
)
1606 struct worker
*worker
, *n
;
1609 lockdep_assert_held(&pool
->assoc_mutex
);
1610 lockdep_assert_held(&pool
->lock
);
1612 /* dequeue and kick idle ones */
1613 list_for_each_entry_safe(worker
, n
, &pool
->idle_list
, entry
) {
1615 * idle workers should be off @pool->idle_list until rebind
1616 * is complete to avoid receiving premature local wake-ups.
1618 list_del_init(&worker
->entry
);
1621 * worker_thread() will see the above dequeuing and call
1622 * idle_worker_rebind().
1624 wake_up_process(worker
->task
);
1627 /* rebind busy workers */
1628 for_each_busy_worker(worker
, i
, pool
) {
1629 struct work_struct
*rebind_work
= &worker
->rebind_work
;
1630 struct workqueue_struct
*wq
;
1632 if (test_and_set_bit(WORK_STRUCT_PENDING_BIT
,
1633 work_data_bits(rebind_work
)))
1636 debug_work_activate(rebind_work
);
1639 * wq doesn't really matter but let's keep @worker->pool
1640 * and @pwq->pool consistent for sanity.
1642 if (worker
->pool
->attrs
->nice
< 0)
1643 wq
= system_highpri_wq
;
1647 insert_work(per_cpu_ptr(wq
->cpu_pwqs
, pool
->cpu
), rebind_work
,
1648 worker
->scheduled
.next
,
1649 work_color_to_flags(WORK_NO_COLOR
));
1653 static struct worker
*alloc_worker(void)
1655 struct worker
*worker
;
1657 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
1659 INIT_LIST_HEAD(&worker
->entry
);
1660 INIT_LIST_HEAD(&worker
->scheduled
);
1661 INIT_WORK(&worker
->rebind_work
, busy_worker_rebind_fn
);
1662 /* on creation a worker is in !idle && prep state */
1663 worker
->flags
= WORKER_PREP
;
1669 * create_worker - create a new workqueue worker
1670 * @pool: pool the new worker will belong to
1672 * Create a new worker which is bound to @pool. The returned worker
1673 * can be started by calling start_worker() or destroyed using
1677 * Might sleep. Does GFP_KERNEL allocations.
1680 * Pointer to the newly created worker.
1682 static struct worker
*create_worker(struct worker_pool
*pool
)
1684 const char *pri
= pool
->attrs
->nice
< 0 ? "H" : "";
1685 struct worker
*worker
= NULL
;
1688 spin_lock_irq(&pool
->lock
);
1689 while (ida_get_new(&pool
->worker_ida
, &id
)) {
1690 spin_unlock_irq(&pool
->lock
);
1691 if (!ida_pre_get(&pool
->worker_ida
, GFP_KERNEL
))
1693 spin_lock_irq(&pool
->lock
);
1695 spin_unlock_irq(&pool
->lock
);
1697 worker
= alloc_worker();
1701 worker
->pool
= pool
;
1705 worker
->task
= kthread_create_on_node(worker_thread
,
1706 worker
, cpu_to_node(pool
->cpu
),
1707 "kworker/%d:%d%s", pool
->cpu
, id
, pri
);
1709 worker
->task
= kthread_create(worker_thread
, worker
,
1712 if (IS_ERR(worker
->task
))
1715 set_user_nice(worker
->task
, pool
->attrs
->nice
);
1716 set_cpus_allowed_ptr(worker
->task
, pool
->attrs
->cpumask
);
1719 * %PF_THREAD_BOUND is used to prevent userland from meddling with
1720 * cpumask of workqueue workers. This is an abuse. We need
1721 * %PF_NO_SETAFFINITY.
1723 worker
->task
->flags
|= PF_THREAD_BOUND
;
1726 * The caller is responsible for ensuring %POOL_DISASSOCIATED
1727 * remains stable across this function. See the comments above the
1728 * flag definition for details.
1730 if (pool
->flags
& POOL_DISASSOCIATED
)
1731 worker
->flags
|= WORKER_UNBOUND
;
1736 spin_lock_irq(&pool
->lock
);
1737 ida_remove(&pool
->worker_ida
, id
);
1738 spin_unlock_irq(&pool
->lock
);
1745 * start_worker - start a newly created worker
1746 * @worker: worker to start
1748 * Make the pool aware of @worker and start it.
1751 * spin_lock_irq(pool->lock).
1753 static void start_worker(struct worker
*worker
)
1755 worker
->flags
|= WORKER_STARTED
;
1756 worker
->pool
->nr_workers
++;
1757 worker_enter_idle(worker
);
1758 wake_up_process(worker
->task
);
1762 * destroy_worker - destroy a workqueue worker
1763 * @worker: worker to be destroyed
1765 * Destroy @worker and adjust @pool stats accordingly.
1768 * spin_lock_irq(pool->lock) which is released and regrabbed.
1770 static void destroy_worker(struct worker
*worker
)
1772 struct worker_pool
*pool
= worker
->pool
;
1773 int id
= worker
->id
;
1775 /* sanity check frenzy */
1776 if (WARN_ON(worker
->current_work
) ||
1777 WARN_ON(!list_empty(&worker
->scheduled
)))
1780 if (worker
->flags
& WORKER_STARTED
)
1782 if (worker
->flags
& WORKER_IDLE
)
1785 list_del_init(&worker
->entry
);
1786 worker
->flags
|= WORKER_DIE
;
1788 spin_unlock_irq(&pool
->lock
);
1790 kthread_stop(worker
->task
);
1793 spin_lock_irq(&pool
->lock
);
1794 ida_remove(&pool
->worker_ida
, id
);
1797 static void idle_worker_timeout(unsigned long __pool
)
1799 struct worker_pool
*pool
= (void *)__pool
;
1801 spin_lock_irq(&pool
->lock
);
1803 if (too_many_workers(pool
)) {
1804 struct worker
*worker
;
1805 unsigned long expires
;
1807 /* idle_list is kept in LIFO order, check the last one */
1808 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
1809 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
1811 if (time_before(jiffies
, expires
))
1812 mod_timer(&pool
->idle_timer
, expires
);
1814 /* it's been idle for too long, wake up manager */
1815 pool
->flags
|= POOL_MANAGE_WORKERS
;
1816 wake_up_worker(pool
);
1820 spin_unlock_irq(&pool
->lock
);
1823 static void send_mayday(struct work_struct
*work
)
1825 struct pool_workqueue
*pwq
= get_work_pwq(work
);
1826 struct workqueue_struct
*wq
= pwq
->wq
;
1828 lockdep_assert_held(&workqueue_lock
);
1830 if (!(wq
->flags
& WQ_RESCUER
))
1833 /* mayday mayday mayday */
1834 if (list_empty(&pwq
->mayday_node
)) {
1835 list_add_tail(&pwq
->mayday_node
, &wq
->maydays
);
1836 wake_up_process(wq
->rescuer
->task
);
1840 static void pool_mayday_timeout(unsigned long __pool
)
1842 struct worker_pool
*pool
= (void *)__pool
;
1843 struct work_struct
*work
;
1845 spin_lock_irq(&workqueue_lock
); /* for wq->maydays */
1846 spin_lock(&pool
->lock
);
1848 if (need_to_create_worker(pool
)) {
1850 * We've been trying to create a new worker but
1851 * haven't been successful. We might be hitting an
1852 * allocation deadlock. Send distress signals to
1855 list_for_each_entry(work
, &pool
->worklist
, entry
)
1859 spin_unlock(&pool
->lock
);
1860 spin_unlock_irq(&workqueue_lock
);
1862 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INTERVAL
);
1866 * maybe_create_worker - create a new worker if necessary
1867 * @pool: pool to create a new worker for
1869 * Create a new worker for @pool if necessary. @pool is guaranteed to
1870 * have at least one idle worker on return from this function. If
1871 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1872 * sent to all rescuers with works scheduled on @pool to resolve
1873 * possible allocation deadlock.
1875 * On return, need_to_create_worker() is guaranteed to be false and
1876 * may_start_working() true.
1879 * spin_lock_irq(pool->lock) which may be released and regrabbed
1880 * multiple times. Does GFP_KERNEL allocations. Called only from
1884 * false if no action was taken and pool->lock stayed locked, true
1887 static bool maybe_create_worker(struct worker_pool
*pool
)
1888 __releases(&pool
->lock
)
1889 __acquires(&pool
->lock
)
1891 if (!need_to_create_worker(pool
))
1894 spin_unlock_irq(&pool
->lock
);
1896 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1897 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INITIAL_TIMEOUT
);
1900 struct worker
*worker
;
1902 worker
= create_worker(pool
);
1904 del_timer_sync(&pool
->mayday_timer
);
1905 spin_lock_irq(&pool
->lock
);
1906 start_worker(worker
);
1907 if (WARN_ON_ONCE(need_to_create_worker(pool
)))
1912 if (!need_to_create_worker(pool
))
1915 __set_current_state(TASK_INTERRUPTIBLE
);
1916 schedule_timeout(CREATE_COOLDOWN
);
1918 if (!need_to_create_worker(pool
))
1922 del_timer_sync(&pool
->mayday_timer
);
1923 spin_lock_irq(&pool
->lock
);
1924 if (need_to_create_worker(pool
))
1930 * maybe_destroy_worker - destroy workers which have been idle for a while
1931 * @pool: pool to destroy workers for
1933 * Destroy @pool workers which have been idle for longer than
1934 * IDLE_WORKER_TIMEOUT.
1937 * spin_lock_irq(pool->lock) which may be released and regrabbed
1938 * multiple times. Called only from manager.
1941 * false if no action was taken and pool->lock stayed locked, true
1944 static bool maybe_destroy_workers(struct worker_pool
*pool
)
1948 while (too_many_workers(pool
)) {
1949 struct worker
*worker
;
1950 unsigned long expires
;
1952 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
1953 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
1955 if (time_before(jiffies
, expires
)) {
1956 mod_timer(&pool
->idle_timer
, expires
);
1960 destroy_worker(worker
);
1968 * manage_workers - manage worker pool
1971 * Assume the manager role and manage the worker pool @worker belongs
1972 * to. At any given time, there can be only zero or one manager per
1973 * pool. The exclusion is handled automatically by this function.
1975 * The caller can safely start processing works on false return. On
1976 * true return, it's guaranteed that need_to_create_worker() is false
1977 * and may_start_working() is true.
1980 * spin_lock_irq(pool->lock) which may be released and regrabbed
1981 * multiple times. Does GFP_KERNEL allocations.
1984 * spin_lock_irq(pool->lock) which may be released and regrabbed
1985 * multiple times. Does GFP_KERNEL allocations.
1987 static bool manage_workers(struct worker
*worker
)
1989 struct worker_pool
*pool
= worker
->pool
;
1992 if (!mutex_trylock(&pool
->manager_arb
))
1996 * To simplify both worker management and CPU hotplug, hold off
1997 * management while hotplug is in progress. CPU hotplug path can't
1998 * grab @pool->manager_arb to achieve this because that can lead to
1999 * idle worker depletion (all become busy thinking someone else is
2000 * managing) which in turn can result in deadlock under extreme
2001 * circumstances. Use @pool->assoc_mutex to synchronize manager
2002 * against CPU hotplug.
2004 * assoc_mutex would always be free unless CPU hotplug is in
2005 * progress. trylock first without dropping @pool->lock.
2007 if (unlikely(!mutex_trylock(&pool
->assoc_mutex
))) {
2008 spin_unlock_irq(&pool
->lock
);
2009 mutex_lock(&pool
->assoc_mutex
);
2011 * CPU hotplug could have happened while we were waiting
2012 * for assoc_mutex. Hotplug itself can't handle us
2013 * because manager isn't either on idle or busy list, and
2014 * @pool's state and ours could have deviated.
2016 * As hotplug is now excluded via assoc_mutex, we can
2017 * simply try to bind. It will succeed or fail depending
2018 * on @pool's current state. Try it and adjust
2019 * %WORKER_UNBOUND accordingly.
2021 if (worker_maybe_bind_and_lock(pool
))
2022 worker
->flags
&= ~WORKER_UNBOUND
;
2024 worker
->flags
|= WORKER_UNBOUND
;
2029 pool
->flags
&= ~POOL_MANAGE_WORKERS
;
2032 * Destroy and then create so that may_start_working() is true
2035 ret
|= maybe_destroy_workers(pool
);
2036 ret
|= maybe_create_worker(pool
);
2038 mutex_unlock(&pool
->assoc_mutex
);
2039 mutex_unlock(&pool
->manager_arb
);
2044 * process_one_work - process single work
2046 * @work: work to process
2048 * Process @work. This function contains all the logics necessary to
2049 * process a single work including synchronization against and
2050 * interaction with other workers on the same cpu, queueing and
2051 * flushing. As long as context requirement is met, any worker can
2052 * call this function to process a work.
2055 * spin_lock_irq(pool->lock) which is released and regrabbed.
2057 static void process_one_work(struct worker
*worker
, struct work_struct
*work
)
2058 __releases(&pool
->lock
)
2059 __acquires(&pool
->lock
)
2061 struct pool_workqueue
*pwq
= get_work_pwq(work
);
2062 struct worker_pool
*pool
= worker
->pool
;
2063 bool cpu_intensive
= pwq
->wq
->flags
& WQ_CPU_INTENSIVE
;
2065 struct worker
*collision
;
2066 #ifdef CONFIG_LOCKDEP
2068 * It is permissible to free the struct work_struct from
2069 * inside the function that is called from it, this we need to
2070 * take into account for lockdep too. To avoid bogus "held
2071 * lock freed" warnings as well as problems when looking into
2072 * work->lockdep_map, make a copy and use that here.
2074 struct lockdep_map lockdep_map
;
2076 lockdep_copy_map(&lockdep_map
, &work
->lockdep_map
);
2079 * Ensure we're on the correct CPU. DISASSOCIATED test is
2080 * necessary to avoid spurious warnings from rescuers servicing the
2081 * unbound or a disassociated pool.
2083 WARN_ON_ONCE(!(worker
->flags
& WORKER_UNBOUND
) &&
2084 !(pool
->flags
& POOL_DISASSOCIATED
) &&
2085 raw_smp_processor_id() != pool
->cpu
);
2088 * A single work shouldn't be executed concurrently by
2089 * multiple workers on a single cpu. Check whether anyone is
2090 * already processing the work. If so, defer the work to the
2091 * currently executing one.
2093 collision
= find_worker_executing_work(pool
, work
);
2094 if (unlikely(collision
)) {
2095 move_linked_works(work
, &collision
->scheduled
, NULL
);
2099 /* claim and dequeue */
2100 debug_work_deactivate(work
);
2101 hash_add(pool
->busy_hash
, &worker
->hentry
, (unsigned long)work
);
2102 worker
->current_work
= work
;
2103 worker
->current_func
= work
->func
;
2104 worker
->current_pwq
= pwq
;
2105 work_color
= get_work_color(work
);
2107 list_del_init(&work
->entry
);
2110 * CPU intensive works don't participate in concurrency
2111 * management. They're the scheduler's responsibility.
2113 if (unlikely(cpu_intensive
))
2114 worker_set_flags(worker
, WORKER_CPU_INTENSIVE
, true);
2117 * Unbound pool isn't concurrency managed and work items should be
2118 * executed ASAP. Wake up another worker if necessary.
2120 if ((worker
->flags
& WORKER_UNBOUND
) && need_more_worker(pool
))
2121 wake_up_worker(pool
);
2124 * Record the last pool and clear PENDING which should be the last
2125 * update to @work. Also, do this inside @pool->lock so that
2126 * PENDING and queued state changes happen together while IRQ is
2129 set_work_pool_and_clear_pending(work
, pool
->id
);
2131 spin_unlock_irq(&pool
->lock
);
2133 lock_map_acquire_read(&pwq
->wq
->lockdep_map
);
2134 lock_map_acquire(&lockdep_map
);
2135 trace_workqueue_execute_start(work
);
2136 worker
->current_func(work
);
2138 * While we must be careful to not use "work" after this, the trace
2139 * point will only record its address.
2141 trace_workqueue_execute_end(work
);
2142 lock_map_release(&lockdep_map
);
2143 lock_map_release(&pwq
->wq
->lockdep_map
);
2145 if (unlikely(in_atomic() || lockdep_depth(current
) > 0)) {
2146 pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
2147 " last function: %pf\n",
2148 current
->comm
, preempt_count(), task_pid_nr(current
),
2149 worker
->current_func
);
2150 debug_show_held_locks(current
);
2154 spin_lock_irq(&pool
->lock
);
2156 /* clear cpu intensive status */
2157 if (unlikely(cpu_intensive
))
2158 worker_clr_flags(worker
, WORKER_CPU_INTENSIVE
);
2160 /* we're done with it, release */
2161 hash_del(&worker
->hentry
);
2162 worker
->current_work
= NULL
;
2163 worker
->current_func
= NULL
;
2164 worker
->current_pwq
= NULL
;
2165 pwq_dec_nr_in_flight(pwq
, work_color
);
2169 * process_scheduled_works - process scheduled works
2172 * Process all scheduled works. Please note that the scheduled list
2173 * may change while processing a work, so this function repeatedly
2174 * fetches a work from the top and executes it.
2177 * spin_lock_irq(pool->lock) which may be released and regrabbed
2180 static void process_scheduled_works(struct worker
*worker
)
2182 while (!list_empty(&worker
->scheduled
)) {
2183 struct work_struct
*work
= list_first_entry(&worker
->scheduled
,
2184 struct work_struct
, entry
);
2185 process_one_work(worker
, work
);
2190 * worker_thread - the worker thread function
2193 * The worker thread function. There are NR_CPU_WORKER_POOLS dynamic pools
2194 * of these per each cpu. These workers process all works regardless of
2195 * their specific target workqueue. The only exception is works which
2196 * belong to workqueues with a rescuer which will be explained in
2199 static int worker_thread(void *__worker
)
2201 struct worker
*worker
= __worker
;
2202 struct worker_pool
*pool
= worker
->pool
;
2204 /* tell the scheduler that this is a workqueue worker */
2205 worker
->task
->flags
|= PF_WQ_WORKER
;
2207 spin_lock_irq(&pool
->lock
);
2209 /* we are off idle list if destruction or rebind is requested */
2210 if (unlikely(list_empty(&worker
->entry
))) {
2211 spin_unlock_irq(&pool
->lock
);
2213 /* if DIE is set, destruction is requested */
2214 if (worker
->flags
& WORKER_DIE
) {
2215 worker
->task
->flags
&= ~PF_WQ_WORKER
;
2219 /* otherwise, rebind */
2220 idle_worker_rebind(worker
);
2224 worker_leave_idle(worker
);
2226 /* no more worker necessary? */
2227 if (!need_more_worker(pool
))
2230 /* do we need to manage? */
2231 if (unlikely(!may_start_working(pool
)) && manage_workers(worker
))
2235 * ->scheduled list can only be filled while a worker is
2236 * preparing to process a work or actually processing it.
2237 * Make sure nobody diddled with it while I was sleeping.
2239 WARN_ON_ONCE(!list_empty(&worker
->scheduled
));
2242 * When control reaches this point, we're guaranteed to have
2243 * at least one idle worker or that someone else has already
2244 * assumed the manager role.
2246 worker_clr_flags(worker
, WORKER_PREP
);
2249 struct work_struct
*work
=
2250 list_first_entry(&pool
->worklist
,
2251 struct work_struct
, entry
);
2253 if (likely(!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))) {
2254 /* optimization path, not strictly necessary */
2255 process_one_work(worker
, work
);
2256 if (unlikely(!list_empty(&worker
->scheduled
)))
2257 process_scheduled_works(worker
);
2259 move_linked_works(work
, &worker
->scheduled
, NULL
);
2260 process_scheduled_works(worker
);
2262 } while (keep_working(pool
));
2264 worker_set_flags(worker
, WORKER_PREP
, false);
2266 if (unlikely(need_to_manage_workers(pool
)) && manage_workers(worker
))
2270 * pool->lock is held and there's no work to process and no need to
2271 * manage, sleep. Workers are woken up only while holding
2272 * pool->lock or from local cpu, so setting the current state
2273 * before releasing pool->lock is enough to prevent losing any
2276 worker_enter_idle(worker
);
2277 __set_current_state(TASK_INTERRUPTIBLE
);
2278 spin_unlock_irq(&pool
->lock
);
2284 * rescuer_thread - the rescuer thread function
2287 * Workqueue rescuer thread function. There's one rescuer for each
2288 * workqueue which has WQ_RESCUER set.
2290 * Regular work processing on a pool may block trying to create a new
2291 * worker which uses GFP_KERNEL allocation which has slight chance of
2292 * developing into deadlock if some works currently on the same queue
2293 * need to be processed to satisfy the GFP_KERNEL allocation. This is
2294 * the problem rescuer solves.
2296 * When such condition is possible, the pool summons rescuers of all
2297 * workqueues which have works queued on the pool and let them process
2298 * those works so that forward progress can be guaranteed.
2300 * This should happen rarely.
2302 static int rescuer_thread(void *__rescuer
)
2304 struct worker
*rescuer
= __rescuer
;
2305 struct workqueue_struct
*wq
= rescuer
->rescue_wq
;
2306 struct list_head
*scheduled
= &rescuer
->scheduled
;
2308 set_user_nice(current
, RESCUER_NICE_LEVEL
);
2311 * Mark rescuer as worker too. As WORKER_PREP is never cleared, it
2312 * doesn't participate in concurrency management.
2314 rescuer
->task
->flags
|= PF_WQ_WORKER
;
2316 set_current_state(TASK_INTERRUPTIBLE
);
2318 if (kthread_should_stop()) {
2319 __set_current_state(TASK_RUNNING
);
2320 rescuer
->task
->flags
&= ~PF_WQ_WORKER
;
2324 /* see whether any pwq is asking for help */
2325 spin_lock_irq(&workqueue_lock
);
2327 while (!list_empty(&wq
->maydays
)) {
2328 struct pool_workqueue
*pwq
= list_first_entry(&wq
->maydays
,
2329 struct pool_workqueue
, mayday_node
);
2330 struct worker_pool
*pool
= pwq
->pool
;
2331 struct work_struct
*work
, *n
;
2333 __set_current_state(TASK_RUNNING
);
2334 list_del_init(&pwq
->mayday_node
);
2336 spin_unlock_irq(&workqueue_lock
);
2338 /* migrate to the target cpu if possible */
2339 worker_maybe_bind_and_lock(pool
);
2340 rescuer
->pool
= pool
;
2343 * Slurp in all works issued via this workqueue and
2346 WARN_ON_ONCE(!list_empty(&rescuer
->scheduled
));
2347 list_for_each_entry_safe(work
, n
, &pool
->worklist
, entry
)
2348 if (get_work_pwq(work
) == pwq
)
2349 move_linked_works(work
, scheduled
, &n
);
2351 process_scheduled_works(rescuer
);
2354 * Leave this pool. If keep_working() is %true, notify a
2355 * regular worker; otherwise, we end up with 0 concurrency
2356 * and stalling the execution.
2358 if (keep_working(pool
))
2359 wake_up_worker(pool
);
2361 rescuer
->pool
= NULL
;
2362 spin_unlock(&pool
->lock
);
2363 spin_lock(&workqueue_lock
);
2366 spin_unlock_irq(&workqueue_lock
);
2368 /* rescuers should never participate in concurrency management */
2369 WARN_ON_ONCE(!(rescuer
->flags
& WORKER_NOT_RUNNING
));
2375 struct work_struct work
;
2376 struct completion done
;
2379 static void wq_barrier_func(struct work_struct
*work
)
2381 struct wq_barrier
*barr
= container_of(work
, struct wq_barrier
, work
);
2382 complete(&barr
->done
);
2386 * insert_wq_barrier - insert a barrier work
2387 * @pwq: pwq to insert barrier into
2388 * @barr: wq_barrier to insert
2389 * @target: target work to attach @barr to
2390 * @worker: worker currently executing @target, NULL if @target is not executing
2392 * @barr is linked to @target such that @barr is completed only after
2393 * @target finishes execution. Please note that the ordering
2394 * guarantee is observed only with respect to @target and on the local
2397 * Currently, a queued barrier can't be canceled. This is because
2398 * try_to_grab_pending() can't determine whether the work to be
2399 * grabbed is at the head of the queue and thus can't clear LINKED
2400 * flag of the previous work while there must be a valid next work
2401 * after a work with LINKED flag set.
2403 * Note that when @worker is non-NULL, @target may be modified
2404 * underneath us, so we can't reliably determine pwq from @target.
2407 * spin_lock_irq(pool->lock).
2409 static void insert_wq_barrier(struct pool_workqueue
*pwq
,
2410 struct wq_barrier
*barr
,
2411 struct work_struct
*target
, struct worker
*worker
)
2413 struct list_head
*head
;
2414 unsigned int linked
= 0;
2417 * debugobject calls are safe here even with pool->lock locked
2418 * as we know for sure that this will not trigger any of the
2419 * checks and call back into the fixup functions where we
2422 INIT_WORK_ONSTACK(&barr
->work
, wq_barrier_func
);
2423 __set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(&barr
->work
));
2424 init_completion(&barr
->done
);
2427 * If @target is currently being executed, schedule the
2428 * barrier to the worker; otherwise, put it after @target.
2431 head
= worker
->scheduled
.next
;
2433 unsigned long *bits
= work_data_bits(target
);
2435 head
= target
->entry
.next
;
2436 /* there can already be other linked works, inherit and set */
2437 linked
= *bits
& WORK_STRUCT_LINKED
;
2438 __set_bit(WORK_STRUCT_LINKED_BIT
, bits
);
2441 debug_work_activate(&barr
->work
);
2442 insert_work(pwq
, &barr
->work
, head
,
2443 work_color_to_flags(WORK_NO_COLOR
) | linked
);
2447 * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
2448 * @wq: workqueue being flushed
2449 * @flush_color: new flush color, < 0 for no-op
2450 * @work_color: new work color, < 0 for no-op
2452 * Prepare pwqs for workqueue flushing.
2454 * If @flush_color is non-negative, flush_color on all pwqs should be
2455 * -1. If no pwq has in-flight commands at the specified color, all
2456 * pwq->flush_color's stay at -1 and %false is returned. If any pwq
2457 * has in flight commands, its pwq->flush_color is set to
2458 * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
2459 * wakeup logic is armed and %true is returned.
2461 * The caller should have initialized @wq->first_flusher prior to
2462 * calling this function with non-negative @flush_color. If
2463 * @flush_color is negative, no flush color update is done and %false
2466 * If @work_color is non-negative, all pwqs should have the same
2467 * work_color which is previous to @work_color and all will be
2468 * advanced to @work_color.
2471 * mutex_lock(wq->flush_mutex).
2474 * %true if @flush_color >= 0 and there's something to flush. %false
2477 static bool flush_workqueue_prep_pwqs(struct workqueue_struct
*wq
,
2478 int flush_color
, int work_color
)
2481 struct pool_workqueue
*pwq
;
2483 if (flush_color
>= 0) {
2484 WARN_ON_ONCE(atomic_read(&wq
->nr_pwqs_to_flush
));
2485 atomic_set(&wq
->nr_pwqs_to_flush
, 1);
2488 local_irq_disable();
2490 for_each_pwq(pwq
, wq
) {
2491 struct worker_pool
*pool
= pwq
->pool
;
2493 spin_lock(&pool
->lock
);
2495 if (flush_color
>= 0) {
2496 WARN_ON_ONCE(pwq
->flush_color
!= -1);
2498 if (pwq
->nr_in_flight
[flush_color
]) {
2499 pwq
->flush_color
= flush_color
;
2500 atomic_inc(&wq
->nr_pwqs_to_flush
);
2505 if (work_color
>= 0) {
2506 WARN_ON_ONCE(work_color
!= work_next_color(pwq
->work_color
));
2507 pwq
->work_color
= work_color
;
2510 spin_unlock(&pool
->lock
);
2515 if (flush_color
>= 0 && atomic_dec_and_test(&wq
->nr_pwqs_to_flush
))
2516 complete(&wq
->first_flusher
->done
);
2522 * flush_workqueue - ensure that any scheduled work has run to completion.
2523 * @wq: workqueue to flush
2525 * Forces execution of the workqueue and blocks until its completion.
2526 * This is typically used in driver shutdown handlers.
2528 * We sleep until all works which were queued on entry have been handled,
2529 * but we are not livelocked by new incoming ones.
2531 void flush_workqueue(struct workqueue_struct
*wq
)
2533 struct wq_flusher this_flusher
= {
2534 .list
= LIST_HEAD_INIT(this_flusher
.list
),
2536 .done
= COMPLETION_INITIALIZER_ONSTACK(this_flusher
.done
),
2540 lock_map_acquire(&wq
->lockdep_map
);
2541 lock_map_release(&wq
->lockdep_map
);
2543 mutex_lock(&wq
->flush_mutex
);
2546 * Start-to-wait phase
2548 next_color
= work_next_color(wq
->work_color
);
2550 if (next_color
!= wq
->flush_color
) {
2552 * Color space is not full. The current work_color
2553 * becomes our flush_color and work_color is advanced
2556 WARN_ON_ONCE(!list_empty(&wq
->flusher_overflow
));
2557 this_flusher
.flush_color
= wq
->work_color
;
2558 wq
->work_color
= next_color
;
2560 if (!wq
->first_flusher
) {
2561 /* no flush in progress, become the first flusher */
2562 WARN_ON_ONCE(wq
->flush_color
!= this_flusher
.flush_color
);
2564 wq
->first_flusher
= &this_flusher
;
2566 if (!flush_workqueue_prep_pwqs(wq
, wq
->flush_color
,
2568 /* nothing to flush, done */
2569 wq
->flush_color
= next_color
;
2570 wq
->first_flusher
= NULL
;
2575 WARN_ON_ONCE(wq
->flush_color
== this_flusher
.flush_color
);
2576 list_add_tail(&this_flusher
.list
, &wq
->flusher_queue
);
2577 flush_workqueue_prep_pwqs(wq
, -1, wq
->work_color
);
2581 * Oops, color space is full, wait on overflow queue.
2582 * The next flush completion will assign us
2583 * flush_color and transfer to flusher_queue.
2585 list_add_tail(&this_flusher
.list
, &wq
->flusher_overflow
);
2588 mutex_unlock(&wq
->flush_mutex
);
2590 wait_for_completion(&this_flusher
.done
);
2593 * Wake-up-and-cascade phase
2595 * First flushers are responsible for cascading flushes and
2596 * handling overflow. Non-first flushers can simply return.
2598 if (wq
->first_flusher
!= &this_flusher
)
2601 mutex_lock(&wq
->flush_mutex
);
2603 /* we might have raced, check again with mutex held */
2604 if (wq
->first_flusher
!= &this_flusher
)
2607 wq
->first_flusher
= NULL
;
2609 WARN_ON_ONCE(!list_empty(&this_flusher
.list
));
2610 WARN_ON_ONCE(wq
->flush_color
!= this_flusher
.flush_color
);
2613 struct wq_flusher
*next
, *tmp
;
2615 /* complete all the flushers sharing the current flush color */
2616 list_for_each_entry_safe(next
, tmp
, &wq
->flusher_queue
, list
) {
2617 if (next
->flush_color
!= wq
->flush_color
)
2619 list_del_init(&next
->list
);
2620 complete(&next
->done
);
2623 WARN_ON_ONCE(!list_empty(&wq
->flusher_overflow
) &&
2624 wq
->flush_color
!= work_next_color(wq
->work_color
));
2626 /* this flush_color is finished, advance by one */
2627 wq
->flush_color
= work_next_color(wq
->flush_color
);
2629 /* one color has been freed, handle overflow queue */
2630 if (!list_empty(&wq
->flusher_overflow
)) {
2632 * Assign the same color to all overflowed
2633 * flushers, advance work_color and append to
2634 * flusher_queue. This is the start-to-wait
2635 * phase for these overflowed flushers.
2637 list_for_each_entry(tmp
, &wq
->flusher_overflow
, list
)
2638 tmp
->flush_color
= wq
->work_color
;
2640 wq
->work_color
= work_next_color(wq
->work_color
);
2642 list_splice_tail_init(&wq
->flusher_overflow
,
2643 &wq
->flusher_queue
);
2644 flush_workqueue_prep_pwqs(wq
, -1, wq
->work_color
);
2647 if (list_empty(&wq
->flusher_queue
)) {
2648 WARN_ON_ONCE(wq
->flush_color
!= wq
->work_color
);
2653 * Need to flush more colors. Make the next flusher
2654 * the new first flusher and arm pwqs.
2656 WARN_ON_ONCE(wq
->flush_color
== wq
->work_color
);
2657 WARN_ON_ONCE(wq
->flush_color
!= next
->flush_color
);
2659 list_del_init(&next
->list
);
2660 wq
->first_flusher
= next
;
2662 if (flush_workqueue_prep_pwqs(wq
, wq
->flush_color
, -1))
2666 * Meh... this color is already done, clear first
2667 * flusher and repeat cascading.
2669 wq
->first_flusher
= NULL
;
2673 mutex_unlock(&wq
->flush_mutex
);
2675 EXPORT_SYMBOL_GPL(flush_workqueue
);
2678 * drain_workqueue - drain a workqueue
2679 * @wq: workqueue to drain
2681 * Wait until the workqueue becomes empty. While draining is in progress,
2682 * only chain queueing is allowed. IOW, only currently pending or running
2683 * work items on @wq can queue further work items on it. @wq is flushed
2684 * repeatedly until it becomes empty. The number of flushing is detemined
2685 * by the depth of chaining and should be relatively short. Whine if it
2688 void drain_workqueue(struct workqueue_struct
*wq
)
2690 unsigned int flush_cnt
= 0;
2691 struct pool_workqueue
*pwq
;
2694 * __queue_work() needs to test whether there are drainers, is much
2695 * hotter than drain_workqueue() and already looks at @wq->flags.
2696 * Use WQ_DRAINING so that queue doesn't have to check nr_drainers.
2698 spin_lock_irq(&workqueue_lock
);
2699 if (!wq
->nr_drainers
++)
2700 wq
->flags
|= WQ_DRAINING
;
2701 spin_unlock_irq(&workqueue_lock
);
2703 flush_workqueue(wq
);
2705 local_irq_disable();
2707 for_each_pwq(pwq
, wq
) {
2710 spin_lock(&pwq
->pool
->lock
);
2711 drained
= !pwq
->nr_active
&& list_empty(&pwq
->delayed_works
);
2712 spin_unlock(&pwq
->pool
->lock
);
2717 if (++flush_cnt
== 10 ||
2718 (flush_cnt
% 100 == 0 && flush_cnt
<= 1000))
2719 pr_warn("workqueue %s: flush on destruction isn't complete after %u tries\n",
2720 wq
->name
, flush_cnt
);
2726 spin_lock(&workqueue_lock
);
2727 if (!--wq
->nr_drainers
)
2728 wq
->flags
&= ~WQ_DRAINING
;
2729 spin_unlock(&workqueue_lock
);
2733 EXPORT_SYMBOL_GPL(drain_workqueue
);
2735 static bool start_flush_work(struct work_struct
*work
, struct wq_barrier
*barr
)
2737 struct worker
*worker
= NULL
;
2738 struct worker_pool
*pool
;
2739 struct pool_workqueue
*pwq
;
2743 local_irq_disable();
2744 pool
= get_work_pool(work
);
2750 spin_lock(&pool
->lock
);
2751 /* see the comment in try_to_grab_pending() with the same code */
2752 pwq
= get_work_pwq(work
);
2754 if (unlikely(pwq
->pool
!= pool
))
2757 worker
= find_worker_executing_work(pool
, work
);
2760 pwq
= worker
->current_pwq
;
2763 insert_wq_barrier(pwq
, barr
, work
, worker
);
2764 spin_unlock_irq(&pool
->lock
);
2767 * If @max_active is 1 or rescuer is in use, flushing another work
2768 * item on the same workqueue may lead to deadlock. Make sure the
2769 * flusher is not running on the same workqueue by verifying write
2772 if (pwq
->wq
->saved_max_active
== 1 || pwq
->wq
->flags
& WQ_RESCUER
)
2773 lock_map_acquire(&pwq
->wq
->lockdep_map
);
2775 lock_map_acquire_read(&pwq
->wq
->lockdep_map
);
2776 lock_map_release(&pwq
->wq
->lockdep_map
);
2780 spin_unlock_irq(&pool
->lock
);
2785 * flush_work - wait for a work to finish executing the last queueing instance
2786 * @work: the work to flush
2788 * Wait until @work has finished execution. @work is guaranteed to be idle
2789 * on return if it hasn't been requeued since flush started.
2792 * %true if flush_work() waited for the work to finish execution,
2793 * %false if it was already idle.
2795 bool flush_work(struct work_struct
*work
)
2797 struct wq_barrier barr
;
2799 lock_map_acquire(&work
->lockdep_map
);
2800 lock_map_release(&work
->lockdep_map
);
2802 if (start_flush_work(work
, &barr
)) {
2803 wait_for_completion(&barr
.done
);
2804 destroy_work_on_stack(&barr
.work
);
2810 EXPORT_SYMBOL_GPL(flush_work
);
2812 static bool __cancel_work_timer(struct work_struct
*work
, bool is_dwork
)
2814 unsigned long flags
;
2818 ret
= try_to_grab_pending(work
, is_dwork
, &flags
);
2820 * If someone else is canceling, wait for the same event it
2821 * would be waiting for before retrying.
2823 if (unlikely(ret
== -ENOENT
))
2825 } while (unlikely(ret
< 0));
2827 /* tell other tasks trying to grab @work to back off */
2828 mark_work_canceling(work
);
2829 local_irq_restore(flags
);
2832 clear_work_data(work
);
2837 * cancel_work_sync - cancel a work and wait for it to finish
2838 * @work: the work to cancel
2840 * Cancel @work and wait for its execution to finish. This function
2841 * can be used even if the work re-queues itself or migrates to
2842 * another workqueue. On return from this function, @work is
2843 * guaranteed to be not pending or executing on any CPU.
2845 * cancel_work_sync(&delayed_work->work) must not be used for
2846 * delayed_work's. Use cancel_delayed_work_sync() instead.
2848 * The caller must ensure that the workqueue on which @work was last
2849 * queued can't be destroyed before this function returns.
2852 * %true if @work was pending, %false otherwise.
2854 bool cancel_work_sync(struct work_struct
*work
)
2856 return __cancel_work_timer(work
, false);
2858 EXPORT_SYMBOL_GPL(cancel_work_sync
);
2861 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2862 * @dwork: the delayed work to flush
2864 * Delayed timer is cancelled and the pending work is queued for
2865 * immediate execution. Like flush_work(), this function only
2866 * considers the last queueing instance of @dwork.
2869 * %true if flush_work() waited for the work to finish execution,
2870 * %false if it was already idle.
2872 bool flush_delayed_work(struct delayed_work
*dwork
)
2874 local_irq_disable();
2875 if (del_timer_sync(&dwork
->timer
))
2876 __queue_work(dwork
->cpu
, dwork
->wq
, &dwork
->work
);
2878 return flush_work(&dwork
->work
);
2880 EXPORT_SYMBOL(flush_delayed_work
);
2883 * cancel_delayed_work - cancel a delayed work
2884 * @dwork: delayed_work to cancel
2886 * Kill off a pending delayed_work. Returns %true if @dwork was pending
2887 * and canceled; %false if wasn't pending. Note that the work callback
2888 * function may still be running on return, unless it returns %true and the
2889 * work doesn't re-arm itself. Explicitly flush or use
2890 * cancel_delayed_work_sync() to wait on it.
2892 * This function is safe to call from any context including IRQ handler.
2894 bool cancel_delayed_work(struct delayed_work
*dwork
)
2896 unsigned long flags
;
2900 ret
= try_to_grab_pending(&dwork
->work
, true, &flags
);
2901 } while (unlikely(ret
== -EAGAIN
));
2903 if (unlikely(ret
< 0))
2906 set_work_pool_and_clear_pending(&dwork
->work
,
2907 get_work_pool_id(&dwork
->work
));
2908 local_irq_restore(flags
);
2911 EXPORT_SYMBOL(cancel_delayed_work
);
2914 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
2915 * @dwork: the delayed work cancel
2917 * This is cancel_work_sync() for delayed works.
2920 * %true if @dwork was pending, %false otherwise.
2922 bool cancel_delayed_work_sync(struct delayed_work
*dwork
)
2924 return __cancel_work_timer(&dwork
->work
, true);
2926 EXPORT_SYMBOL(cancel_delayed_work_sync
);
2929 * schedule_work_on - put work task on a specific cpu
2930 * @cpu: cpu to put the work task on
2931 * @work: job to be done
2933 * This puts a job on a specific cpu
2935 bool schedule_work_on(int cpu
, struct work_struct
*work
)
2937 return queue_work_on(cpu
, system_wq
, work
);
2939 EXPORT_SYMBOL(schedule_work_on
);
2942 * schedule_work - put work task in global workqueue
2943 * @work: job to be done
2945 * Returns %false if @work was already on the kernel-global workqueue and
2948 * This puts a job in the kernel-global workqueue if it was not already
2949 * queued and leaves it in the same position on the kernel-global
2950 * workqueue otherwise.
2952 bool schedule_work(struct work_struct
*work
)
2954 return queue_work(system_wq
, work
);
2956 EXPORT_SYMBOL(schedule_work
);
2959 * schedule_delayed_work_on - queue work in global workqueue on CPU after delay
2961 * @dwork: job to be done
2962 * @delay: number of jiffies to wait
2964 * After waiting for a given time this puts a job in the kernel-global
2965 * workqueue on the specified CPU.
2967 bool schedule_delayed_work_on(int cpu
, struct delayed_work
*dwork
,
2968 unsigned long delay
)
2970 return queue_delayed_work_on(cpu
, system_wq
, dwork
, delay
);
2972 EXPORT_SYMBOL(schedule_delayed_work_on
);
2975 * schedule_delayed_work - put work task in global workqueue after delay
2976 * @dwork: job to be done
2977 * @delay: number of jiffies to wait or 0 for immediate execution
2979 * After waiting for a given time this puts a job in the kernel-global
2982 bool schedule_delayed_work(struct delayed_work
*dwork
, unsigned long delay
)
2984 return queue_delayed_work(system_wq
, dwork
, delay
);
2986 EXPORT_SYMBOL(schedule_delayed_work
);
2989 * schedule_on_each_cpu - execute a function synchronously on each online CPU
2990 * @func: the function to call
2992 * schedule_on_each_cpu() executes @func on each online CPU using the
2993 * system workqueue and blocks until all CPUs have completed.
2994 * schedule_on_each_cpu() is very slow.
2997 * 0 on success, -errno on failure.
2999 int schedule_on_each_cpu(work_func_t func
)
3002 struct work_struct __percpu
*works
;
3004 works
= alloc_percpu(struct work_struct
);
3010 for_each_online_cpu(cpu
) {
3011 struct work_struct
*work
= per_cpu_ptr(works
, cpu
);
3013 INIT_WORK(work
, func
);
3014 schedule_work_on(cpu
, work
);
3017 for_each_online_cpu(cpu
)
3018 flush_work(per_cpu_ptr(works
, cpu
));
3026 * flush_scheduled_work - ensure that any scheduled work has run to completion.
3028 * Forces execution of the kernel-global workqueue and blocks until its
3031 * Think twice before calling this function! It's very easy to get into
3032 * trouble if you don't take great care. Either of the following situations
3033 * will lead to deadlock:
3035 * One of the work items currently on the workqueue needs to acquire
3036 * a lock held by your code or its caller.
3038 * Your code is running in the context of a work routine.
3040 * They will be detected by lockdep when they occur, but the first might not
3041 * occur very often. It depends on what work items are on the workqueue and
3042 * what locks they need, which you have no control over.
3044 * In most situations flushing the entire workqueue is overkill; you merely
3045 * need to know that a particular work item isn't queued and isn't running.
3046 * In such cases you should use cancel_delayed_work_sync() or
3047 * cancel_work_sync() instead.
3049 void flush_scheduled_work(void)
3051 flush_workqueue(system_wq
);
3053 EXPORT_SYMBOL(flush_scheduled_work
);
3056 * execute_in_process_context - reliably execute the routine with user context
3057 * @fn: the function to execute
3058 * @ew: guaranteed storage for the execute work structure (must
3059 * be available when the work executes)
3061 * Executes the function immediately if process context is available,
3062 * otherwise schedules the function for delayed execution.
3064 * Returns: 0 - function was executed
3065 * 1 - function was scheduled for execution
3067 int execute_in_process_context(work_func_t fn
, struct execute_work
*ew
)
3069 if (!in_interrupt()) {
3074 INIT_WORK(&ew
->work
, fn
);
3075 schedule_work(&ew
->work
);
3079 EXPORT_SYMBOL_GPL(execute_in_process_context
);
3081 int keventd_up(void)
3083 return system_wq
!= NULL
;
3087 * free_workqueue_attrs - free a workqueue_attrs
3088 * @attrs: workqueue_attrs to free
3090 * Undo alloc_workqueue_attrs().
3092 void free_workqueue_attrs(struct workqueue_attrs
*attrs
)
3095 free_cpumask_var(attrs
->cpumask
);
3101 * alloc_workqueue_attrs - allocate a workqueue_attrs
3102 * @gfp_mask: allocation mask to use
3104 * Allocate a new workqueue_attrs, initialize with default settings and
3105 * return it. Returns NULL on failure.
3107 struct workqueue_attrs
*alloc_workqueue_attrs(gfp_t gfp_mask
)
3109 struct workqueue_attrs
*attrs
;
3111 attrs
= kzalloc(sizeof(*attrs
), gfp_mask
);
3114 if (!alloc_cpumask_var(&attrs
->cpumask
, gfp_mask
))
3117 cpumask_setall(attrs
->cpumask
);
3120 free_workqueue_attrs(attrs
);
3124 static void copy_workqueue_attrs(struct workqueue_attrs
*to
,
3125 const struct workqueue_attrs
*from
)
3127 to
->nice
= from
->nice
;
3128 cpumask_copy(to
->cpumask
, from
->cpumask
);
3132 * Hacky implementation of jhash of bitmaps which only considers the
3133 * specified number of bits. We probably want a proper implementation in
3134 * include/linux/jhash.h.
3136 static u32
jhash_bitmap(const unsigned long *bitmap
, int bits
, u32 hash
)
3138 int nr_longs
= bits
/ BITS_PER_LONG
;
3139 int nr_leftover
= bits
% BITS_PER_LONG
;
3140 unsigned long leftover
= 0;
3143 hash
= jhash(bitmap
, nr_longs
* sizeof(long), hash
);
3145 bitmap_copy(&leftover
, bitmap
+ nr_longs
, nr_leftover
);
3146 hash
= jhash(&leftover
, sizeof(long), hash
);
3151 /* hash value of the content of @attr */
3152 static u32
wqattrs_hash(const struct workqueue_attrs
*attrs
)
3156 hash
= jhash_1word(attrs
->nice
, hash
);
3157 hash
= jhash_bitmap(cpumask_bits(attrs
->cpumask
), nr_cpu_ids
, hash
);
3161 /* content equality test */
3162 static bool wqattrs_equal(const struct workqueue_attrs
*a
,
3163 const struct workqueue_attrs
*b
)
3165 if (a
->nice
!= b
->nice
)
3167 if (!cpumask_equal(a
->cpumask
, b
->cpumask
))
3173 * init_worker_pool - initialize a newly zalloc'd worker_pool
3174 * @pool: worker_pool to initialize
3176 * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs.
3177 * Returns 0 on success, -errno on failure. Even on failure, all fields
3178 * inside @pool proper are initialized and put_unbound_pool() can be called
3179 * on @pool safely to release it.
3181 static int init_worker_pool(struct worker_pool
*pool
)
3183 spin_lock_init(&pool
->lock
);
3186 pool
->flags
|= POOL_DISASSOCIATED
;
3187 INIT_LIST_HEAD(&pool
->worklist
);
3188 INIT_LIST_HEAD(&pool
->idle_list
);
3189 hash_init(pool
->busy_hash
);
3191 init_timer_deferrable(&pool
->idle_timer
);
3192 pool
->idle_timer
.function
= idle_worker_timeout
;
3193 pool
->idle_timer
.data
= (unsigned long)pool
;
3195 setup_timer(&pool
->mayday_timer
, pool_mayday_timeout
,
3196 (unsigned long)pool
);
3198 mutex_init(&pool
->manager_arb
);
3199 mutex_init(&pool
->assoc_mutex
);
3200 ida_init(&pool
->worker_ida
);
3202 INIT_HLIST_NODE(&pool
->hash_node
);
3205 /* shouldn't fail above this point */
3206 pool
->attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3212 static void rcu_free_pool(struct rcu_head
*rcu
)
3214 struct worker_pool
*pool
= container_of(rcu
, struct worker_pool
, rcu
);
3216 ida_destroy(&pool
->worker_ida
);
3217 free_workqueue_attrs(pool
->attrs
);
3222 * put_unbound_pool - put a worker_pool
3223 * @pool: worker_pool to put
3225 * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU
3228 static void put_unbound_pool(struct worker_pool
*pool
)
3230 struct worker
*worker
;
3232 spin_lock_irq(&workqueue_lock
);
3233 if (--pool
->refcnt
) {
3234 spin_unlock_irq(&workqueue_lock
);
3239 if (WARN_ON(!(pool
->flags
& POOL_DISASSOCIATED
)) ||
3240 WARN_ON(!list_empty(&pool
->worklist
))) {
3241 spin_unlock_irq(&workqueue_lock
);
3245 /* release id and unhash */
3247 idr_remove(&worker_pool_idr
, pool
->id
);
3248 hash_del(&pool
->hash_node
);
3250 spin_unlock_irq(&workqueue_lock
);
3252 /* lock out manager and destroy all workers */
3253 mutex_lock(&pool
->manager_arb
);
3254 spin_lock_irq(&pool
->lock
);
3256 while ((worker
= first_worker(pool
)))
3257 destroy_worker(worker
);
3258 WARN_ON(pool
->nr_workers
|| pool
->nr_idle
);
3260 spin_unlock_irq(&pool
->lock
);
3261 mutex_unlock(&pool
->manager_arb
);
3263 /* shut down the timers */
3264 del_timer_sync(&pool
->idle_timer
);
3265 del_timer_sync(&pool
->mayday_timer
);
3267 /* sched-RCU protected to allow dereferences from get_work_pool() */
3268 call_rcu_sched(&pool
->rcu
, rcu_free_pool
);
3272 * get_unbound_pool - get a worker_pool with the specified attributes
3273 * @attrs: the attributes of the worker_pool to get
3275 * Obtain a worker_pool which has the same attributes as @attrs, bump the
3276 * reference count and return it. If there already is a matching
3277 * worker_pool, it will be used; otherwise, this function attempts to
3278 * create a new one. On failure, returns NULL.
3280 static struct worker_pool
*get_unbound_pool(const struct workqueue_attrs
*attrs
)
3282 static DEFINE_MUTEX(create_mutex
);
3283 u32 hash
= wqattrs_hash(attrs
);
3284 struct worker_pool
*pool
;
3285 struct worker
*worker
;
3287 mutex_lock(&create_mutex
);
3289 /* do we already have a matching pool? */
3290 spin_lock_irq(&workqueue_lock
);
3291 hash_for_each_possible(unbound_pool_hash
, pool
, hash_node
, hash
) {
3292 if (wqattrs_equal(pool
->attrs
, attrs
)) {
3297 spin_unlock_irq(&workqueue_lock
);
3299 /* nope, create a new one */
3300 pool
= kzalloc(sizeof(*pool
), GFP_KERNEL
);
3301 if (!pool
|| init_worker_pool(pool
) < 0)
3304 copy_workqueue_attrs(pool
->attrs
, attrs
);
3306 if (worker_pool_assign_id(pool
) < 0)
3309 /* create and start the initial worker */
3310 worker
= create_worker(pool
);
3314 spin_lock_irq(&pool
->lock
);
3315 start_worker(worker
);
3316 spin_unlock_irq(&pool
->lock
);
3319 spin_lock_irq(&workqueue_lock
);
3320 hash_add(unbound_pool_hash
, &pool
->hash_node
, hash
);
3322 spin_unlock_irq(&workqueue_lock
);
3323 mutex_unlock(&create_mutex
);
3326 mutex_unlock(&create_mutex
);
3328 put_unbound_pool(pool
);
3332 static int alloc_and_link_pwqs(struct workqueue_struct
*wq
)
3334 bool highpri
= wq
->flags
& WQ_HIGHPRI
;
3337 if (!(wq
->flags
& WQ_UNBOUND
)) {
3338 wq
->cpu_pwqs
= alloc_percpu(struct pool_workqueue
);
3342 for_each_possible_cpu(cpu
) {
3343 struct pool_workqueue
*pwq
=
3344 per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
3345 struct worker_pool
*cpu_pools
=
3346 per_cpu(cpu_worker_pools
, cpu
);
3348 pwq
->pool
= &cpu_pools
[highpri
];
3349 list_add_tail_rcu(&pwq
->pwqs_node
, &wq
->pwqs
);
3352 struct pool_workqueue
*pwq
;
3354 pwq
= kmem_cache_zalloc(pwq_cache
, GFP_KERNEL
);
3358 pwq
->pool
= get_unbound_pool(unbound_std_wq_attrs
[highpri
]);
3360 kmem_cache_free(pwq_cache
, pwq
);
3364 list_add_tail_rcu(&pwq
->pwqs_node
, &wq
->pwqs
);
3370 static void free_pwqs(struct workqueue_struct
*wq
)
3372 if (!(wq
->flags
& WQ_UNBOUND
))
3373 free_percpu(wq
->cpu_pwqs
);
3374 else if (!list_empty(&wq
->pwqs
))
3375 kmem_cache_free(pwq_cache
, list_first_entry(&wq
->pwqs
,
3376 struct pool_workqueue
, pwqs_node
));
3379 static int wq_clamp_max_active(int max_active
, unsigned int flags
,
3382 int lim
= flags
& WQ_UNBOUND
? WQ_UNBOUND_MAX_ACTIVE
: WQ_MAX_ACTIVE
;
3384 if (max_active
< 1 || max_active
> lim
)
3385 pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
3386 max_active
, name
, 1, lim
);
3388 return clamp_val(max_active
, 1, lim
);
3391 struct workqueue_struct
*__alloc_workqueue_key(const char *fmt
,
3394 struct lock_class_key
*key
,
3395 const char *lock_name
, ...)
3397 va_list args
, args1
;
3398 struct workqueue_struct
*wq
;
3399 struct pool_workqueue
*pwq
;
3402 /* determine namelen, allocate wq and format name */
3403 va_start(args
, lock_name
);
3404 va_copy(args1
, args
);
3405 namelen
= vsnprintf(NULL
, 0, fmt
, args
) + 1;
3407 wq
= kzalloc(sizeof(*wq
) + namelen
, GFP_KERNEL
);
3411 vsnprintf(wq
->name
, namelen
, fmt
, args1
);
3416 * Workqueues which may be used during memory reclaim should
3417 * have a rescuer to guarantee forward progress.
3419 if (flags
& WQ_MEM_RECLAIM
)
3420 flags
|= WQ_RESCUER
;
3422 max_active
= max_active
?: WQ_DFL_ACTIVE
;
3423 max_active
= wq_clamp_max_active(max_active
, flags
, wq
->name
);
3427 wq
->saved_max_active
= max_active
;
3428 mutex_init(&wq
->flush_mutex
);
3429 atomic_set(&wq
->nr_pwqs_to_flush
, 0);
3430 INIT_LIST_HEAD(&wq
->pwqs
);
3431 INIT_LIST_HEAD(&wq
->flusher_queue
);
3432 INIT_LIST_HEAD(&wq
->flusher_overflow
);
3433 INIT_LIST_HEAD(&wq
->maydays
);
3435 lockdep_init_map(&wq
->lockdep_map
, lock_name
, key
, 0);
3436 INIT_LIST_HEAD(&wq
->list
);
3438 if (alloc_and_link_pwqs(wq
) < 0)
3441 local_irq_disable();
3442 for_each_pwq(pwq
, wq
) {
3443 BUG_ON((unsigned long)pwq
& WORK_STRUCT_FLAG_MASK
);
3445 pwq
->flush_color
= -1;
3446 pwq
->max_active
= max_active
;
3447 INIT_LIST_HEAD(&pwq
->delayed_works
);
3448 INIT_LIST_HEAD(&pwq
->mayday_node
);
3452 if (flags
& WQ_RESCUER
) {
3453 struct worker
*rescuer
;
3455 wq
->rescuer
= rescuer
= alloc_worker();
3459 rescuer
->rescue_wq
= wq
;
3460 rescuer
->task
= kthread_create(rescuer_thread
, rescuer
, "%s",
3462 if (IS_ERR(rescuer
->task
))
3465 rescuer
->task
->flags
|= PF_THREAD_BOUND
;
3466 wake_up_process(rescuer
->task
);
3470 * workqueue_lock protects global freeze state and workqueues
3471 * list. Grab it, set max_active accordingly and add the new
3472 * workqueue to workqueues list.
3474 spin_lock_irq(&workqueue_lock
);
3476 if (workqueue_freezing
&& wq
->flags
& WQ_FREEZABLE
)
3477 for_each_pwq(pwq
, wq
)
3478 pwq
->max_active
= 0;
3480 list_add(&wq
->list
, &workqueues
);
3482 spin_unlock_irq(&workqueue_lock
);
3493 EXPORT_SYMBOL_GPL(__alloc_workqueue_key
);
3496 * destroy_workqueue - safely terminate a workqueue
3497 * @wq: target workqueue
3499 * Safely destroy a workqueue. All work currently pending will be done first.
3501 void destroy_workqueue(struct workqueue_struct
*wq
)
3503 struct pool_workqueue
*pwq
;
3505 /* drain it before proceeding with destruction */
3506 drain_workqueue(wq
);
3508 spin_lock_irq(&workqueue_lock
);
3511 for_each_pwq(pwq
, wq
) {
3514 for (i
= 0; i
< WORK_NR_COLORS
; i
++) {
3515 if (WARN_ON(pwq
->nr_in_flight
[i
])) {
3516 spin_unlock_irq(&workqueue_lock
);
3521 if (WARN_ON(pwq
->nr_active
) ||
3522 WARN_ON(!list_empty(&pwq
->delayed_works
))) {
3523 spin_unlock_irq(&workqueue_lock
);
3529 * wq list is used to freeze wq, remove from list after
3530 * flushing is complete in case freeze races us.
3532 list_del(&wq
->list
);
3534 spin_unlock_irq(&workqueue_lock
);
3536 if (wq
->flags
& WQ_RESCUER
) {
3537 kthread_stop(wq
->rescuer
->task
);
3542 * We're the sole accessor of @wq at this point. Directly access
3543 * the first pwq and put its pool.
3545 if (wq
->flags
& WQ_UNBOUND
) {
3546 pwq
= list_first_entry(&wq
->pwqs
, struct pool_workqueue
,
3548 put_unbound_pool(pwq
->pool
);
3553 EXPORT_SYMBOL_GPL(destroy_workqueue
);
3556 * pwq_set_max_active - adjust max_active of a pwq
3557 * @pwq: target pool_workqueue
3558 * @max_active: new max_active value.
3560 * Set @pwq->max_active to @max_active and activate delayed works if
3564 * spin_lock_irq(pool->lock).
3566 static void pwq_set_max_active(struct pool_workqueue
*pwq
, int max_active
)
3568 pwq
->max_active
= max_active
;
3570 while (!list_empty(&pwq
->delayed_works
) &&
3571 pwq
->nr_active
< pwq
->max_active
)
3572 pwq_activate_first_delayed(pwq
);
3576 * workqueue_set_max_active - adjust max_active of a workqueue
3577 * @wq: target workqueue
3578 * @max_active: new max_active value.
3580 * Set max_active of @wq to @max_active.
3583 * Don't call from IRQ context.
3585 void workqueue_set_max_active(struct workqueue_struct
*wq
, int max_active
)
3587 struct pool_workqueue
*pwq
;
3589 max_active
= wq_clamp_max_active(max_active
, wq
->flags
, wq
->name
);
3591 spin_lock_irq(&workqueue_lock
);
3593 wq
->saved_max_active
= max_active
;
3595 for_each_pwq(pwq
, wq
) {
3596 struct worker_pool
*pool
= pwq
->pool
;
3598 spin_lock(&pool
->lock
);
3600 if (!(wq
->flags
& WQ_FREEZABLE
) ||
3601 !(pool
->flags
& POOL_FREEZING
))
3602 pwq_set_max_active(pwq
, max_active
);
3604 spin_unlock(&pool
->lock
);
3607 spin_unlock_irq(&workqueue_lock
);
3609 EXPORT_SYMBOL_GPL(workqueue_set_max_active
);
3612 * workqueue_congested - test whether a workqueue is congested
3613 * @cpu: CPU in question
3614 * @wq: target workqueue
3616 * Test whether @wq's cpu workqueue for @cpu is congested. There is
3617 * no synchronization around this function and the test result is
3618 * unreliable and only useful as advisory hints or for debugging.
3621 * %true if congested, %false otherwise.
3623 bool workqueue_congested(int cpu
, struct workqueue_struct
*wq
)
3625 struct pool_workqueue
*pwq
;
3630 if (!(wq
->flags
& WQ_UNBOUND
))
3631 pwq
= per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
3633 pwq
= first_pwq(wq
);
3635 ret
= !list_empty(&pwq
->delayed_works
);
3640 EXPORT_SYMBOL_GPL(workqueue_congested
);
3643 * work_busy - test whether a work is currently pending or running
3644 * @work: the work to be tested
3646 * Test whether @work is currently pending or running. There is no
3647 * synchronization around this function and the test result is
3648 * unreliable and only useful as advisory hints or for debugging.
3651 * OR'd bitmask of WORK_BUSY_* bits.
3653 unsigned int work_busy(struct work_struct
*work
)
3655 struct worker_pool
*pool
;
3656 unsigned long flags
;
3657 unsigned int ret
= 0;
3659 if (work_pending(work
))
3660 ret
|= WORK_BUSY_PENDING
;
3662 local_irq_save(flags
);
3663 pool
= get_work_pool(work
);
3665 spin_lock(&pool
->lock
);
3666 if (find_worker_executing_work(pool
, work
))
3667 ret
|= WORK_BUSY_RUNNING
;
3668 spin_unlock(&pool
->lock
);
3670 local_irq_restore(flags
);
3674 EXPORT_SYMBOL_GPL(work_busy
);
3679 * There are two challenges in supporting CPU hotplug. Firstly, there
3680 * are a lot of assumptions on strong associations among work, pwq and
3681 * pool which make migrating pending and scheduled works very
3682 * difficult to implement without impacting hot paths. Secondly,
3683 * worker pools serve mix of short, long and very long running works making
3684 * blocked draining impractical.
3686 * This is solved by allowing the pools to be disassociated from the CPU
3687 * running as an unbound one and allowing it to be reattached later if the
3688 * cpu comes back online.
3691 static void wq_unbind_fn(struct work_struct
*work
)
3693 int cpu
= smp_processor_id();
3694 struct worker_pool
*pool
;
3695 struct worker
*worker
;
3698 for_each_cpu_worker_pool(pool
, cpu
) {
3699 WARN_ON_ONCE(cpu
!= smp_processor_id());
3701 mutex_lock(&pool
->assoc_mutex
);
3702 spin_lock_irq(&pool
->lock
);
3705 * We've claimed all manager positions. Make all workers
3706 * unbound and set DISASSOCIATED. Before this, all workers
3707 * except for the ones which are still executing works from
3708 * before the last CPU down must be on the cpu. After
3709 * this, they may become diasporas.
3711 list_for_each_entry(worker
, &pool
->idle_list
, entry
)
3712 worker
->flags
|= WORKER_UNBOUND
;
3714 for_each_busy_worker(worker
, i
, pool
)
3715 worker
->flags
|= WORKER_UNBOUND
;
3717 pool
->flags
|= POOL_DISASSOCIATED
;
3719 spin_unlock_irq(&pool
->lock
);
3720 mutex_unlock(&pool
->assoc_mutex
);
3724 * Call schedule() so that we cross rq->lock and thus can guarantee
3725 * sched callbacks see the %WORKER_UNBOUND flag. This is necessary
3726 * as scheduler callbacks may be invoked from other cpus.
3731 * Sched callbacks are disabled now. Zap nr_running. After this,
3732 * nr_running stays zero and need_more_worker() and keep_working()
3733 * are always true as long as the worklist is not empty. Pools on
3734 * @cpu now behave as unbound (in terms of concurrency management)
3735 * pools which are served by workers tied to the CPU.
3737 * On return from this function, the current worker would trigger
3738 * unbound chain execution of pending work items if other workers
3741 for_each_cpu_worker_pool(pool
, cpu
)
3742 atomic_set(&pool
->nr_running
, 0);
3746 * Workqueues should be brought up before normal priority CPU notifiers.
3747 * This will be registered high priority CPU notifier.
3749 static int __cpuinit
workqueue_cpu_up_callback(struct notifier_block
*nfb
,
3750 unsigned long action
,
3753 int cpu
= (unsigned long)hcpu
;
3754 struct worker_pool
*pool
;
3756 switch (action
& ~CPU_TASKS_FROZEN
) {
3757 case CPU_UP_PREPARE
:
3758 for_each_cpu_worker_pool(pool
, cpu
) {
3759 struct worker
*worker
;
3761 if (pool
->nr_workers
)
3764 worker
= create_worker(pool
);
3768 spin_lock_irq(&pool
->lock
);
3769 start_worker(worker
);
3770 spin_unlock_irq(&pool
->lock
);
3774 case CPU_DOWN_FAILED
:
3776 for_each_cpu_worker_pool(pool
, cpu
) {
3777 mutex_lock(&pool
->assoc_mutex
);
3778 spin_lock_irq(&pool
->lock
);
3780 pool
->flags
&= ~POOL_DISASSOCIATED
;
3781 rebind_workers(pool
);
3783 spin_unlock_irq(&pool
->lock
);
3784 mutex_unlock(&pool
->assoc_mutex
);
3792 * Workqueues should be brought down after normal priority CPU notifiers.
3793 * This will be registered as low priority CPU notifier.
3795 static int __cpuinit
workqueue_cpu_down_callback(struct notifier_block
*nfb
,
3796 unsigned long action
,
3799 int cpu
= (unsigned long)hcpu
;
3800 struct work_struct unbind_work
;
3802 switch (action
& ~CPU_TASKS_FROZEN
) {
3803 case CPU_DOWN_PREPARE
:
3804 /* unbinding should happen on the local CPU */
3805 INIT_WORK_ONSTACK(&unbind_work
, wq_unbind_fn
);
3806 queue_work_on(cpu
, system_highpri_wq
, &unbind_work
);
3807 flush_work(&unbind_work
);
3815 struct work_for_cpu
{
3816 struct work_struct work
;
3822 static void work_for_cpu_fn(struct work_struct
*work
)
3824 struct work_for_cpu
*wfc
= container_of(work
, struct work_for_cpu
, work
);
3826 wfc
->ret
= wfc
->fn(wfc
->arg
);
3830 * work_on_cpu - run a function in user context on a particular cpu
3831 * @cpu: the cpu to run on
3832 * @fn: the function to run
3833 * @arg: the function arg
3835 * This will return the value @fn returns.
3836 * It is up to the caller to ensure that the cpu doesn't go offline.
3837 * The caller must not hold any locks which would prevent @fn from completing.
3839 long work_on_cpu(int cpu
, long (*fn
)(void *), void *arg
)
3841 struct work_for_cpu wfc
= { .fn
= fn
, .arg
= arg
};
3843 INIT_WORK_ONSTACK(&wfc
.work
, work_for_cpu_fn
);
3844 schedule_work_on(cpu
, &wfc
.work
);
3845 flush_work(&wfc
.work
);
3848 EXPORT_SYMBOL_GPL(work_on_cpu
);
3849 #endif /* CONFIG_SMP */
3851 #ifdef CONFIG_FREEZER
3854 * freeze_workqueues_begin - begin freezing workqueues
3856 * Start freezing workqueues. After this function returns, all freezable
3857 * workqueues will queue new works to their frozen_works list instead of
3861 * Grabs and releases workqueue_lock and pool->lock's.
3863 void freeze_workqueues_begin(void)
3865 struct worker_pool
*pool
;
3866 struct workqueue_struct
*wq
;
3867 struct pool_workqueue
*pwq
;
3870 spin_lock_irq(&workqueue_lock
);
3872 WARN_ON_ONCE(workqueue_freezing
);
3873 workqueue_freezing
= true;
3876 for_each_pool(pool
, id
) {
3877 spin_lock(&pool
->lock
);
3878 WARN_ON_ONCE(pool
->flags
& POOL_FREEZING
);
3879 pool
->flags
|= POOL_FREEZING
;
3880 spin_unlock(&pool
->lock
);
3883 /* suppress further executions by setting max_active to zero */
3884 list_for_each_entry(wq
, &workqueues
, list
) {
3885 if (!(wq
->flags
& WQ_FREEZABLE
))
3888 for_each_pwq(pwq
, wq
) {
3889 spin_lock(&pwq
->pool
->lock
);
3890 pwq
->max_active
= 0;
3891 spin_unlock(&pwq
->pool
->lock
);
3895 spin_unlock_irq(&workqueue_lock
);
3899 * freeze_workqueues_busy - are freezable workqueues still busy?
3901 * Check whether freezing is complete. This function must be called
3902 * between freeze_workqueues_begin() and thaw_workqueues().
3905 * Grabs and releases workqueue_lock.
3908 * %true if some freezable workqueues are still busy. %false if freezing
3911 bool freeze_workqueues_busy(void)
3914 struct workqueue_struct
*wq
;
3915 struct pool_workqueue
*pwq
;
3917 spin_lock_irq(&workqueue_lock
);
3919 WARN_ON_ONCE(!workqueue_freezing
);
3921 list_for_each_entry(wq
, &workqueues
, list
) {
3922 if (!(wq
->flags
& WQ_FREEZABLE
))
3925 * nr_active is monotonically decreasing. It's safe
3926 * to peek without lock.
3928 for_each_pwq(pwq
, wq
) {
3929 WARN_ON_ONCE(pwq
->nr_active
< 0);
3930 if (pwq
->nr_active
) {
3937 spin_unlock_irq(&workqueue_lock
);
3942 * thaw_workqueues - thaw workqueues
3944 * Thaw workqueues. Normal queueing is restored and all collected
3945 * frozen works are transferred to their respective pool worklists.
3948 * Grabs and releases workqueue_lock and pool->lock's.
3950 void thaw_workqueues(void)
3952 struct workqueue_struct
*wq
;
3953 struct pool_workqueue
*pwq
;
3954 struct worker_pool
*pool
;
3957 spin_lock_irq(&workqueue_lock
);
3959 if (!workqueue_freezing
)
3962 /* clear FREEZING */
3963 for_each_pool(pool
, id
) {
3964 spin_lock(&pool
->lock
);
3965 WARN_ON_ONCE(!(pool
->flags
& POOL_FREEZING
));
3966 pool
->flags
&= ~POOL_FREEZING
;
3967 spin_unlock(&pool
->lock
);
3970 /* restore max_active and repopulate worklist */
3971 list_for_each_entry(wq
, &workqueues
, list
) {
3972 if (!(wq
->flags
& WQ_FREEZABLE
))
3975 for_each_pwq(pwq
, wq
) {
3976 spin_lock(&pwq
->pool
->lock
);
3977 pwq_set_max_active(pwq
, wq
->saved_max_active
);
3978 spin_unlock(&pwq
->pool
->lock
);
3983 for_each_pool(pool
, id
) {
3984 spin_lock(&pool
->lock
);
3985 wake_up_worker(pool
);
3986 spin_unlock(&pool
->lock
);
3989 workqueue_freezing
= false;
3991 spin_unlock_irq(&workqueue_lock
);
3993 #endif /* CONFIG_FREEZER */
3995 static int __init
init_workqueues(void)
3997 int std_nice
[NR_STD_WORKER_POOLS
] = { 0, HIGHPRI_NICE_LEVEL
};
4000 /* make sure we have enough bits for OFFQ pool ID */
4001 BUILD_BUG_ON((1LU << (BITS_PER_LONG
- WORK_OFFQ_POOL_SHIFT
)) <
4002 WORK_CPU_END
* NR_STD_WORKER_POOLS
);
4004 WARN_ON(__alignof__(struct pool_workqueue
) < __alignof__(long long));
4006 pwq_cache
= KMEM_CACHE(pool_workqueue
, SLAB_PANIC
);
4008 cpu_notifier(workqueue_cpu_up_callback
, CPU_PRI_WORKQUEUE_UP
);
4009 hotcpu_notifier(workqueue_cpu_down_callback
, CPU_PRI_WORKQUEUE_DOWN
);
4011 /* initialize CPU pools */
4012 for_each_possible_cpu(cpu
) {
4013 struct worker_pool
*pool
;
4016 for_each_cpu_worker_pool(pool
, cpu
) {
4017 BUG_ON(init_worker_pool(pool
));
4019 cpumask_copy(pool
->attrs
->cpumask
, cpumask_of(cpu
));
4020 pool
->attrs
->nice
= std_nice
[i
++];
4023 BUG_ON(worker_pool_assign_id(pool
));
4027 /* create the initial worker */
4028 for_each_online_cpu(cpu
) {
4029 struct worker_pool
*pool
;
4031 for_each_cpu_worker_pool(pool
, cpu
) {
4032 struct worker
*worker
;
4034 pool
->flags
&= ~POOL_DISASSOCIATED
;
4036 worker
= create_worker(pool
);
4038 spin_lock_irq(&pool
->lock
);
4039 start_worker(worker
);
4040 spin_unlock_irq(&pool
->lock
);
4044 /* create default unbound wq attrs */
4045 for (i
= 0; i
< NR_STD_WORKER_POOLS
; i
++) {
4046 struct workqueue_attrs
*attrs
;
4048 BUG_ON(!(attrs
= alloc_workqueue_attrs(GFP_KERNEL
)));
4050 attrs
->nice
= std_nice
[i
];
4051 cpumask_setall(attrs
->cpumask
);
4053 unbound_std_wq_attrs
[i
] = attrs
;
4056 system_wq
= alloc_workqueue("events", 0, 0);
4057 system_highpri_wq
= alloc_workqueue("events_highpri", WQ_HIGHPRI
, 0);
4058 system_long_wq
= alloc_workqueue("events_long", 0, 0);
4059 system_unbound_wq
= alloc_workqueue("events_unbound", WQ_UNBOUND
,
4060 WQ_UNBOUND_MAX_ACTIVE
);
4061 system_freezable_wq
= alloc_workqueue("events_freezable",
4063 BUG_ON(!system_wq
|| !system_highpri_wq
|| !system_long_wq
||
4064 !system_unbound_wq
|| !system_freezable_wq
);
4067 early_initcall(init_workqueues
);