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 are two worker pools for each CPU (one for
20 * normal work items and the other for high priority ones) and some extra
21 * pools for workqueues which are not bound to any specific CPU - the
22 * number of these backing pools is dynamic.
24 * Please read Documentation/workqueue.txt for details.
27 #include <linux/export.h>
28 #include <linux/kernel.h>
29 #include <linux/sched.h>
30 #include <linux/init.h>
31 #include <linux/signal.h>
32 #include <linux/completion.h>
33 #include <linux/workqueue.h>
34 #include <linux/slab.h>
35 #include <linux/cpu.h>
36 #include <linux/notifier.h>
37 #include <linux/kthread.h>
38 #include <linux/hardirq.h>
39 #include <linux/mempolicy.h>
40 #include <linux/freezer.h>
41 #include <linux/kallsyms.h>
42 #include <linux/debug_locks.h>
43 #include <linux/lockdep.h>
44 #include <linux/idr.h>
45 #include <linux/jhash.h>
46 #include <linux/hashtable.h>
47 #include <linux/rculist.h>
48 #include <linux/nodemask.h>
49 #include <linux/moduleparam.h>
50 #include <linux/uaccess.h>
52 #include "workqueue_internal.h"
58 * A bound pool is either associated or disassociated with its CPU.
59 * While associated (!DISASSOCIATED), all workers are bound to the
60 * CPU and none has %WORKER_UNBOUND set and concurrency management
63 * While DISASSOCIATED, the cpu may be offline and all workers have
64 * %WORKER_UNBOUND set and concurrency management disabled, and may
65 * be executing on any CPU. The pool behaves as an unbound one.
67 * Note that DISASSOCIATED should be flipped only while holding
68 * attach_mutex to avoid changing binding state while
69 * worker_attach_to_pool() is in progress.
71 POOL_DISASSOCIATED
= 1 << 2, /* cpu can't serve workers */
74 WORKER_DIE
= 1 << 1, /* die die die */
75 WORKER_IDLE
= 1 << 2, /* is idle */
76 WORKER_PREP
= 1 << 3, /* preparing to run works */
77 WORKER_CPU_INTENSIVE
= 1 << 6, /* cpu intensive */
78 WORKER_UNBOUND
= 1 << 7, /* worker is unbound */
79 WORKER_REBOUND
= 1 << 8, /* worker was rebound */
81 WORKER_NOT_RUNNING
= WORKER_PREP
| WORKER_CPU_INTENSIVE
|
82 WORKER_UNBOUND
| WORKER_REBOUND
,
84 NR_STD_WORKER_POOLS
= 2, /* # standard pools per cpu */
86 UNBOUND_POOL_HASH_ORDER
= 6, /* hashed by pool->attrs */
87 BUSY_WORKER_HASH_ORDER
= 6, /* 64 pointers */
89 MAX_IDLE_WORKERS_RATIO
= 4, /* 1/4 of busy can be idle */
90 IDLE_WORKER_TIMEOUT
= 300 * HZ
, /* keep idle ones for 5 mins */
92 MAYDAY_INITIAL_TIMEOUT
= HZ
/ 100 >= 2 ? HZ
/ 100 : 2,
93 /* call for help after 10ms
95 MAYDAY_INTERVAL
= HZ
/ 10, /* and then every 100ms */
96 CREATE_COOLDOWN
= HZ
, /* time to breath after fail */
99 * Rescue workers are used only on emergencies and shared by
100 * all cpus. Give MIN_NICE.
102 RESCUER_NICE_LEVEL
= MIN_NICE
,
103 HIGHPRI_NICE_LEVEL
= MIN_NICE
,
109 * Structure fields follow one of the following exclusion rules.
111 * I: Modifiable by initialization/destruction paths and read-only for
114 * P: Preemption protected. Disabling preemption is enough and should
115 * only be modified and accessed from the local cpu.
117 * L: pool->lock protected. Access with pool->lock held.
119 * X: During normal operation, modification requires pool->lock and should
120 * be done only from local cpu. Either disabling preemption on local
121 * cpu or grabbing pool->lock is enough for read access. If
122 * POOL_DISASSOCIATED is set, it's identical to L.
124 * A: pool->attach_mutex protected.
126 * PL: wq_pool_mutex protected.
128 * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads.
130 * PW: wq_pool_mutex and wq->mutex protected for writes. Either for reads.
132 * PWR: wq_pool_mutex and wq->mutex protected for writes. Either or
133 * sched-RCU for reads.
135 * WQ: wq->mutex protected.
137 * WR: wq->mutex protected for writes. Sched-RCU protected for reads.
139 * MD: wq_mayday_lock protected.
142 /* struct worker is defined in workqueue_internal.h */
145 spinlock_t lock
; /* the pool lock */
146 int cpu
; /* I: the associated cpu */
147 int node
; /* I: the associated node ID */
148 int id
; /* I: pool ID */
149 unsigned int flags
; /* X: flags */
151 struct list_head worklist
; /* L: list of pending works */
152 int nr_workers
; /* L: total number of workers */
154 /* nr_idle includes the ones off idle_list for rebinding */
155 int nr_idle
; /* L: currently idle ones */
157 struct list_head idle_list
; /* X: list of idle workers */
158 struct timer_list idle_timer
; /* L: worker idle timeout */
159 struct timer_list mayday_timer
; /* L: SOS timer for workers */
161 /* a workers is either on busy_hash or idle_list, or the manager */
162 DECLARE_HASHTABLE(busy_hash
, BUSY_WORKER_HASH_ORDER
);
163 /* L: hash of busy workers */
165 /* see manage_workers() for details on the two manager mutexes */
166 struct mutex manager_arb
; /* manager arbitration */
167 struct worker
*manager
; /* L: purely informational */
168 struct mutex attach_mutex
; /* attach/detach exclusion */
169 struct list_head workers
; /* A: attached workers */
170 struct completion
*detach_completion
; /* all workers detached */
172 struct ida worker_ida
; /* worker IDs for task name */
174 struct workqueue_attrs
*attrs
; /* I: worker attributes */
175 struct hlist_node hash_node
; /* PL: unbound_pool_hash node */
176 int refcnt
; /* PL: refcnt for unbound pools */
179 * The current concurrency level. As it's likely to be accessed
180 * from other CPUs during try_to_wake_up(), put it in a separate
183 atomic_t nr_running ____cacheline_aligned_in_smp
;
186 * Destruction of pool is sched-RCU protected to allow dereferences
187 * from get_work_pool().
190 } ____cacheline_aligned_in_smp
;
193 * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
194 * of work_struct->data are used for flags and the remaining high bits
195 * point to the pwq; thus, pwqs need to be aligned at two's power of the
196 * number of flag bits.
198 struct pool_workqueue
{
199 struct worker_pool
*pool
; /* I: the associated pool */
200 struct workqueue_struct
*wq
; /* I: the owning workqueue */
201 int work_color
; /* L: current color */
202 int flush_color
; /* L: flushing color */
203 int refcnt
; /* L: reference count */
204 int nr_in_flight
[WORK_NR_COLORS
];
205 /* L: nr of in_flight works */
206 int nr_active
; /* L: nr of active works */
207 int max_active
; /* L: max active works */
208 struct list_head delayed_works
; /* L: delayed works */
209 struct list_head pwqs_node
; /* WR: node on wq->pwqs */
210 struct list_head mayday_node
; /* MD: node on wq->maydays */
213 * Release of unbound pwq is punted to system_wq. See put_pwq()
214 * and pwq_unbound_release_workfn() for details. pool_workqueue
215 * itself is also sched-RCU protected so that the first pwq can be
216 * determined without grabbing wq->mutex.
218 struct work_struct unbound_release_work
;
220 } __aligned(1 << WORK_STRUCT_FLAG_BITS
);
223 * Structure used to wait for workqueue flush.
226 struct list_head list
; /* WQ: list of flushers */
227 int flush_color
; /* WQ: flush color waiting for */
228 struct completion done
; /* flush completion */
234 * The externally visible workqueue. It relays the issued work items to
235 * the appropriate worker_pool through its pool_workqueues.
237 struct workqueue_struct
{
238 struct list_head pwqs
; /* WR: all pwqs of this wq */
239 struct list_head list
; /* PR: list of all workqueues */
241 struct mutex mutex
; /* protects this wq */
242 int work_color
; /* WQ: current work color */
243 int flush_color
; /* WQ: current flush color */
244 atomic_t nr_pwqs_to_flush
; /* flush in progress */
245 struct wq_flusher
*first_flusher
; /* WQ: first flusher */
246 struct list_head flusher_queue
; /* WQ: flush waiters */
247 struct list_head flusher_overflow
; /* WQ: flush overflow list */
249 struct list_head maydays
; /* MD: pwqs requesting rescue */
250 struct worker
*rescuer
; /* I: rescue worker */
252 int nr_drainers
; /* WQ: drain in progress */
253 int saved_max_active
; /* WQ: saved pwq max_active */
255 struct workqueue_attrs
*unbound_attrs
; /* PW: only for unbound wqs */
256 struct pool_workqueue
*dfl_pwq
; /* PW: only for unbound wqs */
259 struct wq_device
*wq_dev
; /* I: for sysfs interface */
261 #ifdef CONFIG_LOCKDEP
262 struct lockdep_map lockdep_map
;
264 char name
[WQ_NAME_LEN
]; /* I: workqueue name */
267 * Destruction of workqueue_struct is sched-RCU protected to allow
268 * walking the workqueues list without grabbing wq_pool_mutex.
269 * This is used to dump all workqueues from sysrq.
273 /* hot fields used during command issue, aligned to cacheline */
274 unsigned int flags ____cacheline_aligned
; /* WQ: WQ_* flags */
275 struct pool_workqueue __percpu
*cpu_pwqs
; /* I: per-cpu pwqs */
276 struct pool_workqueue __rcu
*numa_pwq_tbl
[]; /* PWR: unbound pwqs indexed by node */
279 static struct kmem_cache
*pwq_cache
;
281 static cpumask_var_t
*wq_numa_possible_cpumask
;
282 /* possible CPUs of each node */
284 static bool wq_disable_numa
;
285 module_param_named(disable_numa
, wq_disable_numa
, bool, 0444);
287 /* see the comment above the definition of WQ_POWER_EFFICIENT */
288 #ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT
289 static bool wq_power_efficient
= true;
291 static bool wq_power_efficient
;
294 module_param_named(power_efficient
, wq_power_efficient
, bool, 0444);
296 static bool wq_numa_enabled
; /* unbound NUMA affinity enabled */
298 /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
299 static struct workqueue_attrs
*wq_update_unbound_numa_attrs_buf
;
301 static DEFINE_MUTEX(wq_pool_mutex
); /* protects pools and workqueues list */
302 static DEFINE_SPINLOCK(wq_mayday_lock
); /* protects wq->maydays list */
304 static LIST_HEAD(workqueues
); /* PR: list of all workqueues */
305 static bool workqueue_freezing
; /* PL: have wqs started freezing? */
307 static cpumask_var_t wq_unbound_cpumask
; /* PL: low level cpumask for all unbound wqs */
309 /* the per-cpu worker pools */
310 static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool
[NR_STD_WORKER_POOLS
],
313 static DEFINE_IDR(worker_pool_idr
); /* PR: idr of all pools */
315 /* PL: hash of all unbound pools keyed by pool->attrs */
316 static DEFINE_HASHTABLE(unbound_pool_hash
, UNBOUND_POOL_HASH_ORDER
);
318 /* I: attributes used when instantiating standard unbound pools on demand */
319 static struct workqueue_attrs
*unbound_std_wq_attrs
[NR_STD_WORKER_POOLS
];
321 /* I: attributes used when instantiating ordered pools on demand */
322 static struct workqueue_attrs
*ordered_wq_attrs
[NR_STD_WORKER_POOLS
];
324 struct workqueue_struct
*system_wq __read_mostly
;
325 EXPORT_SYMBOL(system_wq
);
326 struct workqueue_struct
*system_highpri_wq __read_mostly
;
327 EXPORT_SYMBOL_GPL(system_highpri_wq
);
328 struct workqueue_struct
*system_long_wq __read_mostly
;
329 EXPORT_SYMBOL_GPL(system_long_wq
);
330 struct workqueue_struct
*system_unbound_wq __read_mostly
;
331 EXPORT_SYMBOL_GPL(system_unbound_wq
);
332 struct workqueue_struct
*system_freezable_wq __read_mostly
;
333 EXPORT_SYMBOL_GPL(system_freezable_wq
);
334 struct workqueue_struct
*system_power_efficient_wq __read_mostly
;
335 EXPORT_SYMBOL_GPL(system_power_efficient_wq
);
336 struct workqueue_struct
*system_freezable_power_efficient_wq __read_mostly
;
337 EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq
);
339 static int worker_thread(void *__worker
);
340 static void copy_workqueue_attrs(struct workqueue_attrs
*to
,
341 const struct workqueue_attrs
*from
);
342 static void workqueue_sysfs_unregister(struct workqueue_struct
*wq
);
344 #define CREATE_TRACE_POINTS
345 #include <trace/events/workqueue.h>
347 #define assert_rcu_or_pool_mutex() \
348 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
349 lockdep_is_held(&wq_pool_mutex), \
350 "sched RCU or wq_pool_mutex should be held")
352 #define assert_rcu_or_wq_mutex(wq) \
353 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
354 lockdep_is_held(&wq->mutex), \
355 "sched RCU or wq->mutex should be held")
357 #define assert_rcu_or_wq_mutex_or_pool_mutex(wq) \
358 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
359 lockdep_is_held(&wq->mutex) || \
360 lockdep_is_held(&wq_pool_mutex), \
361 "sched RCU, wq->mutex or wq_pool_mutex should be held")
363 #define for_each_cpu_worker_pool(pool, cpu) \
364 for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
365 (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
369 * for_each_pool - iterate through all worker_pools in the system
370 * @pool: iteration cursor
371 * @pi: integer used for iteration
373 * This must be called either with wq_pool_mutex held or sched RCU read
374 * locked. If the pool needs to be used beyond the locking in effect, the
375 * caller is responsible for guaranteeing that the pool stays online.
377 * The if/else clause exists only for the lockdep assertion and can be
380 #define for_each_pool(pool, pi) \
381 idr_for_each_entry(&worker_pool_idr, pool, pi) \
382 if (({ assert_rcu_or_pool_mutex(); false; })) { } \
386 * for_each_pool_worker - iterate through all workers of a worker_pool
387 * @worker: iteration cursor
388 * @pool: worker_pool to iterate workers of
390 * This must be called with @pool->attach_mutex.
392 * The if/else clause exists only for the lockdep assertion and can be
395 #define for_each_pool_worker(worker, pool) \
396 list_for_each_entry((worker), &(pool)->workers, node) \
397 if (({ lockdep_assert_held(&pool->attach_mutex); false; })) { } \
401 * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
402 * @pwq: iteration cursor
403 * @wq: the target workqueue
405 * This must be called either with wq->mutex held or sched RCU read locked.
406 * If the pwq needs to be used beyond the locking in effect, the caller is
407 * responsible for guaranteeing that the pwq stays online.
409 * The if/else clause exists only for the lockdep assertion and can be
412 #define for_each_pwq(pwq, wq) \
413 list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
414 if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
417 #ifdef CONFIG_DEBUG_OBJECTS_WORK
419 static struct debug_obj_descr work_debug_descr
;
421 static void *work_debug_hint(void *addr
)
423 return ((struct work_struct
*) addr
)->func
;
427 * fixup_init is called when:
428 * - an active object is initialized
430 static int work_fixup_init(void *addr
, enum debug_obj_state state
)
432 struct work_struct
*work
= addr
;
435 case ODEBUG_STATE_ACTIVE
:
436 cancel_work_sync(work
);
437 debug_object_init(work
, &work_debug_descr
);
445 * fixup_activate is called when:
446 * - an active object is activated
447 * - an unknown object is activated (might be a statically initialized object)
449 static int work_fixup_activate(void *addr
, enum debug_obj_state state
)
451 struct work_struct
*work
= addr
;
455 case ODEBUG_STATE_NOTAVAILABLE
:
457 * This is not really a fixup. The work struct was
458 * statically initialized. We just make sure that it
459 * is tracked in the object tracker.
461 if (test_bit(WORK_STRUCT_STATIC_BIT
, work_data_bits(work
))) {
462 debug_object_init(work
, &work_debug_descr
);
463 debug_object_activate(work
, &work_debug_descr
);
469 case ODEBUG_STATE_ACTIVE
:
478 * fixup_free is called when:
479 * - an active object is freed
481 static int work_fixup_free(void *addr
, enum debug_obj_state state
)
483 struct work_struct
*work
= addr
;
486 case ODEBUG_STATE_ACTIVE
:
487 cancel_work_sync(work
);
488 debug_object_free(work
, &work_debug_descr
);
495 static struct debug_obj_descr work_debug_descr
= {
496 .name
= "work_struct",
497 .debug_hint
= work_debug_hint
,
498 .fixup_init
= work_fixup_init
,
499 .fixup_activate
= work_fixup_activate
,
500 .fixup_free
= work_fixup_free
,
503 static inline void debug_work_activate(struct work_struct
*work
)
505 debug_object_activate(work
, &work_debug_descr
);
508 static inline void debug_work_deactivate(struct work_struct
*work
)
510 debug_object_deactivate(work
, &work_debug_descr
);
513 void __init_work(struct work_struct
*work
, int onstack
)
516 debug_object_init_on_stack(work
, &work_debug_descr
);
518 debug_object_init(work
, &work_debug_descr
);
520 EXPORT_SYMBOL_GPL(__init_work
);
522 void destroy_work_on_stack(struct work_struct
*work
)
524 debug_object_free(work
, &work_debug_descr
);
526 EXPORT_SYMBOL_GPL(destroy_work_on_stack
);
528 void destroy_delayed_work_on_stack(struct delayed_work
*work
)
530 destroy_timer_on_stack(&work
->timer
);
531 debug_object_free(&work
->work
, &work_debug_descr
);
533 EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack
);
536 static inline void debug_work_activate(struct work_struct
*work
) { }
537 static inline void debug_work_deactivate(struct work_struct
*work
) { }
541 * worker_pool_assign_id - allocate ID and assing it to @pool
542 * @pool: the pool pointer of interest
544 * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned
545 * successfully, -errno on failure.
547 static int worker_pool_assign_id(struct worker_pool
*pool
)
551 lockdep_assert_held(&wq_pool_mutex
);
553 ret
= idr_alloc(&worker_pool_idr
, pool
, 0, WORK_OFFQ_POOL_NONE
,
563 * unbound_pwq_by_node - return the unbound pool_workqueue for the given node
564 * @wq: the target workqueue
567 * This must be called with any of wq_pool_mutex, wq->mutex or sched RCU
569 * If the pwq needs to be used beyond the locking in effect, the caller is
570 * responsible for guaranteeing that the pwq stays online.
572 * Return: The unbound pool_workqueue for @node.
574 static struct pool_workqueue
*unbound_pwq_by_node(struct workqueue_struct
*wq
,
577 assert_rcu_or_wq_mutex_or_pool_mutex(wq
);
578 return rcu_dereference_raw(wq
->numa_pwq_tbl
[node
]);
581 static unsigned int work_color_to_flags(int color
)
583 return color
<< WORK_STRUCT_COLOR_SHIFT
;
586 static int get_work_color(struct work_struct
*work
)
588 return (*work_data_bits(work
) >> WORK_STRUCT_COLOR_SHIFT
) &
589 ((1 << WORK_STRUCT_COLOR_BITS
) - 1);
592 static int work_next_color(int color
)
594 return (color
+ 1) % WORK_NR_COLORS
;
598 * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
599 * contain the pointer to the queued pwq. Once execution starts, the flag
600 * is cleared and the high bits contain OFFQ flags and pool ID.
602 * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
603 * and clear_work_data() can be used to set the pwq, pool or clear
604 * work->data. These functions should only be called while the work is
605 * owned - ie. while the PENDING bit is set.
607 * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
608 * corresponding to a work. Pool is available once the work has been
609 * queued anywhere after initialization until it is sync canceled. pwq is
610 * available only while the work item is queued.
612 * %WORK_OFFQ_CANCELING is used to mark a work item which is being
613 * canceled. While being canceled, a work item may have its PENDING set
614 * but stay off timer and worklist for arbitrarily long and nobody should
615 * try to steal the PENDING bit.
617 static inline void set_work_data(struct work_struct
*work
, unsigned long data
,
620 WARN_ON_ONCE(!work_pending(work
));
621 atomic_long_set(&work
->data
, data
| flags
| work_static(work
));
624 static void set_work_pwq(struct work_struct
*work
, struct pool_workqueue
*pwq
,
625 unsigned long extra_flags
)
627 set_work_data(work
, (unsigned long)pwq
,
628 WORK_STRUCT_PENDING
| WORK_STRUCT_PWQ
| extra_flags
);
631 static void set_work_pool_and_keep_pending(struct work_struct
*work
,
634 set_work_data(work
, (unsigned long)pool_id
<< WORK_OFFQ_POOL_SHIFT
,
635 WORK_STRUCT_PENDING
);
638 static void set_work_pool_and_clear_pending(struct work_struct
*work
,
642 * The following wmb is paired with the implied mb in
643 * test_and_set_bit(PENDING) and ensures all updates to @work made
644 * here are visible to and precede any updates by the next PENDING
648 set_work_data(work
, (unsigned long)pool_id
<< WORK_OFFQ_POOL_SHIFT
, 0);
651 static void clear_work_data(struct work_struct
*work
)
653 smp_wmb(); /* see set_work_pool_and_clear_pending() */
654 set_work_data(work
, WORK_STRUCT_NO_POOL
, 0);
657 static struct pool_workqueue
*get_work_pwq(struct work_struct
*work
)
659 unsigned long data
= atomic_long_read(&work
->data
);
661 if (data
& WORK_STRUCT_PWQ
)
662 return (void *)(data
& WORK_STRUCT_WQ_DATA_MASK
);
668 * get_work_pool - return the worker_pool a given work was associated with
669 * @work: the work item of interest
671 * Pools are created and destroyed under wq_pool_mutex, and allows read
672 * access under sched-RCU read lock. As such, this function should be
673 * called under wq_pool_mutex or with preemption disabled.
675 * All fields of the returned pool are accessible as long as the above
676 * mentioned locking is in effect. If the returned pool needs to be used
677 * beyond the critical section, the caller is responsible for ensuring the
678 * returned pool is and stays online.
680 * Return: The worker_pool @work was last associated with. %NULL if none.
682 static struct worker_pool
*get_work_pool(struct work_struct
*work
)
684 unsigned long data
= atomic_long_read(&work
->data
);
687 assert_rcu_or_pool_mutex();
689 if (data
& WORK_STRUCT_PWQ
)
690 return ((struct pool_workqueue
*)
691 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
;
693 pool_id
= data
>> WORK_OFFQ_POOL_SHIFT
;
694 if (pool_id
== WORK_OFFQ_POOL_NONE
)
697 return idr_find(&worker_pool_idr
, pool_id
);
701 * get_work_pool_id - return the worker pool ID a given work is associated with
702 * @work: the work item of interest
704 * Return: The worker_pool ID @work was last associated with.
705 * %WORK_OFFQ_POOL_NONE if none.
707 static int get_work_pool_id(struct work_struct
*work
)
709 unsigned long data
= atomic_long_read(&work
->data
);
711 if (data
& WORK_STRUCT_PWQ
)
712 return ((struct pool_workqueue
*)
713 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
->id
;
715 return data
>> WORK_OFFQ_POOL_SHIFT
;
718 static void mark_work_canceling(struct work_struct
*work
)
720 unsigned long pool_id
= get_work_pool_id(work
);
722 pool_id
<<= WORK_OFFQ_POOL_SHIFT
;
723 set_work_data(work
, pool_id
| WORK_OFFQ_CANCELING
, WORK_STRUCT_PENDING
);
726 static bool work_is_canceling(struct work_struct
*work
)
728 unsigned long data
= atomic_long_read(&work
->data
);
730 return !(data
& WORK_STRUCT_PWQ
) && (data
& WORK_OFFQ_CANCELING
);
734 * Policy functions. These define the policies on how the global worker
735 * pools are managed. Unless noted otherwise, these functions assume that
736 * they're being called with pool->lock held.
739 static bool __need_more_worker(struct worker_pool
*pool
)
741 return !atomic_read(&pool
->nr_running
);
745 * Need to wake up a worker? Called from anything but currently
748 * Note that, because unbound workers never contribute to nr_running, this
749 * function will always return %true for unbound pools as long as the
750 * worklist isn't empty.
752 static bool need_more_worker(struct worker_pool
*pool
)
754 return !list_empty(&pool
->worklist
) && __need_more_worker(pool
);
757 /* Can I start working? Called from busy but !running workers. */
758 static bool may_start_working(struct worker_pool
*pool
)
760 return pool
->nr_idle
;
763 /* Do I need to keep working? Called from currently running workers. */
764 static bool keep_working(struct worker_pool
*pool
)
766 return !list_empty(&pool
->worklist
) &&
767 atomic_read(&pool
->nr_running
) <= 1;
770 /* Do we need a new worker? Called from manager. */
771 static bool need_to_create_worker(struct worker_pool
*pool
)
773 return need_more_worker(pool
) && !may_start_working(pool
);
776 /* Do we have too many workers and should some go away? */
777 static bool too_many_workers(struct worker_pool
*pool
)
779 bool managing
= mutex_is_locked(&pool
->manager_arb
);
780 int nr_idle
= pool
->nr_idle
+ managing
; /* manager is considered idle */
781 int nr_busy
= pool
->nr_workers
- nr_idle
;
783 return nr_idle
> 2 && (nr_idle
- 2) * MAX_IDLE_WORKERS_RATIO
>= nr_busy
;
790 /* Return the first idle worker. Safe with preemption disabled */
791 static struct worker
*first_idle_worker(struct worker_pool
*pool
)
793 if (unlikely(list_empty(&pool
->idle_list
)))
796 return list_first_entry(&pool
->idle_list
, struct worker
, entry
);
800 * wake_up_worker - wake up an idle worker
801 * @pool: worker pool to wake worker from
803 * Wake up the first idle worker of @pool.
806 * spin_lock_irq(pool->lock).
808 static void wake_up_worker(struct worker_pool
*pool
)
810 struct worker
*worker
= first_idle_worker(pool
);
813 wake_up_process(worker
->task
);
817 * wq_worker_waking_up - a worker is waking up
818 * @task: task waking up
819 * @cpu: CPU @task is waking up to
821 * This function is called during try_to_wake_up() when a worker is
825 * spin_lock_irq(rq->lock)
827 void wq_worker_waking_up(struct task_struct
*task
, int cpu
)
829 struct worker
*worker
= kthread_data(task
);
831 if (!(worker
->flags
& WORKER_NOT_RUNNING
)) {
832 WARN_ON_ONCE(worker
->pool
->cpu
!= cpu
);
833 atomic_inc(&worker
->pool
->nr_running
);
838 * wq_worker_sleeping - a worker is going to sleep
839 * @task: task going to sleep
840 * @cpu: CPU in question, must be the current CPU number
842 * This function is called during schedule() when a busy worker is
843 * going to sleep. Worker on the same cpu can be woken up by
844 * returning pointer to its task.
847 * spin_lock_irq(rq->lock)
850 * Worker task on @cpu to wake up, %NULL if none.
852 struct task_struct
*wq_worker_sleeping(struct task_struct
*task
, int cpu
)
854 struct worker
*worker
= kthread_data(task
), *to_wakeup
= NULL
;
855 struct worker_pool
*pool
;
858 * Rescuers, which may not have all the fields set up like normal
859 * workers, also reach here, let's not access anything before
860 * checking NOT_RUNNING.
862 if (worker
->flags
& WORKER_NOT_RUNNING
)
867 /* this can only happen on the local cpu */
868 if (WARN_ON_ONCE(cpu
!= raw_smp_processor_id() || pool
->cpu
!= cpu
))
872 * The counterpart of the following dec_and_test, implied mb,
873 * worklist not empty test sequence is in insert_work().
874 * Please read comment there.
876 * NOT_RUNNING is clear. This means that we're bound to and
877 * running on the local cpu w/ rq lock held and preemption
878 * disabled, which in turn means that none else could be
879 * manipulating idle_list, so dereferencing idle_list without pool
882 if (atomic_dec_and_test(&pool
->nr_running
) &&
883 !list_empty(&pool
->worklist
))
884 to_wakeup
= first_idle_worker(pool
);
885 return to_wakeup
? to_wakeup
->task
: NULL
;
889 * worker_set_flags - set worker flags and adjust nr_running accordingly
891 * @flags: flags to set
893 * Set @flags in @worker->flags and adjust nr_running accordingly.
896 * spin_lock_irq(pool->lock)
898 static inline void worker_set_flags(struct worker
*worker
, unsigned int flags
)
900 struct worker_pool
*pool
= worker
->pool
;
902 WARN_ON_ONCE(worker
->task
!= current
);
904 /* If transitioning into NOT_RUNNING, adjust nr_running. */
905 if ((flags
& WORKER_NOT_RUNNING
) &&
906 !(worker
->flags
& WORKER_NOT_RUNNING
)) {
907 atomic_dec(&pool
->nr_running
);
910 worker
->flags
|= flags
;
914 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
916 * @flags: flags to clear
918 * Clear @flags in @worker->flags and adjust nr_running accordingly.
921 * spin_lock_irq(pool->lock)
923 static inline void worker_clr_flags(struct worker
*worker
, unsigned int flags
)
925 struct worker_pool
*pool
= worker
->pool
;
926 unsigned int oflags
= worker
->flags
;
928 WARN_ON_ONCE(worker
->task
!= current
);
930 worker
->flags
&= ~flags
;
933 * If transitioning out of NOT_RUNNING, increment nr_running. Note
934 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
935 * of multiple flags, not a single flag.
937 if ((flags
& WORKER_NOT_RUNNING
) && (oflags
& WORKER_NOT_RUNNING
))
938 if (!(worker
->flags
& WORKER_NOT_RUNNING
))
939 atomic_inc(&pool
->nr_running
);
943 * find_worker_executing_work - find worker which is executing a work
944 * @pool: pool of interest
945 * @work: work to find worker for
947 * Find a worker which is executing @work on @pool by searching
948 * @pool->busy_hash which is keyed by the address of @work. For a worker
949 * to match, its current execution should match the address of @work and
950 * its work function. This is to avoid unwanted dependency between
951 * unrelated work executions through a work item being recycled while still
954 * This is a bit tricky. A work item may be freed once its execution
955 * starts and nothing prevents the freed area from being recycled for
956 * another work item. If the same work item address ends up being reused
957 * before the original execution finishes, workqueue will identify the
958 * recycled work item as currently executing and make it wait until the
959 * current execution finishes, introducing an unwanted dependency.
961 * This function checks the work item address and work function to avoid
962 * false positives. Note that this isn't complete as one may construct a
963 * work function which can introduce dependency onto itself through a
964 * recycled work item. Well, if somebody wants to shoot oneself in the
965 * foot that badly, there's only so much we can do, and if such deadlock
966 * actually occurs, it should be easy to locate the culprit work function.
969 * spin_lock_irq(pool->lock).
972 * Pointer to worker which is executing @work if found, %NULL
975 static struct worker
*find_worker_executing_work(struct worker_pool
*pool
,
976 struct work_struct
*work
)
978 struct worker
*worker
;
980 hash_for_each_possible(pool
->busy_hash
, worker
, hentry
,
982 if (worker
->current_work
== work
&&
983 worker
->current_func
== work
->func
)
990 * move_linked_works - move linked works to a list
991 * @work: start of series of works to be scheduled
992 * @head: target list to append @work to
993 * @nextp: out paramter for nested worklist walking
995 * Schedule linked works starting from @work to @head. Work series to
996 * be scheduled starts at @work and includes any consecutive work with
997 * WORK_STRUCT_LINKED set in its predecessor.
999 * If @nextp is not NULL, it's updated to point to the next work of
1000 * the last scheduled work. This allows move_linked_works() to be
1001 * nested inside outer list_for_each_entry_safe().
1004 * spin_lock_irq(pool->lock).
1006 static void move_linked_works(struct work_struct
*work
, struct list_head
*head
,
1007 struct work_struct
**nextp
)
1009 struct work_struct
*n
;
1012 * Linked worklist will always end before the end of the list,
1013 * use NULL for list head.
1015 list_for_each_entry_safe_from(work
, n
, NULL
, entry
) {
1016 list_move_tail(&work
->entry
, head
);
1017 if (!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))
1022 * If we're already inside safe list traversal and have moved
1023 * multiple works to the scheduled queue, the next position
1024 * needs to be updated.
1031 * get_pwq - get an extra reference on the specified pool_workqueue
1032 * @pwq: pool_workqueue to get
1034 * Obtain an extra reference on @pwq. The caller should guarantee that
1035 * @pwq has positive refcnt and be holding the matching pool->lock.
1037 static void get_pwq(struct pool_workqueue
*pwq
)
1039 lockdep_assert_held(&pwq
->pool
->lock
);
1040 WARN_ON_ONCE(pwq
->refcnt
<= 0);
1045 * put_pwq - put a pool_workqueue reference
1046 * @pwq: pool_workqueue to put
1048 * Drop a reference of @pwq. If its refcnt reaches zero, schedule its
1049 * destruction. The caller should be holding the matching pool->lock.
1051 static void put_pwq(struct pool_workqueue
*pwq
)
1053 lockdep_assert_held(&pwq
->pool
->lock
);
1054 if (likely(--pwq
->refcnt
))
1056 if (WARN_ON_ONCE(!(pwq
->wq
->flags
& WQ_UNBOUND
)))
1059 * @pwq can't be released under pool->lock, bounce to
1060 * pwq_unbound_release_workfn(). This never recurses on the same
1061 * pool->lock as this path is taken only for unbound workqueues and
1062 * the release work item is scheduled on a per-cpu workqueue. To
1063 * avoid lockdep warning, unbound pool->locks are given lockdep
1064 * subclass of 1 in get_unbound_pool().
1066 schedule_work(&pwq
->unbound_release_work
);
1070 * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
1071 * @pwq: pool_workqueue to put (can be %NULL)
1073 * put_pwq() with locking. This function also allows %NULL @pwq.
1075 static void put_pwq_unlocked(struct pool_workqueue
*pwq
)
1079 * As both pwqs and pools are sched-RCU protected, the
1080 * following lock operations are safe.
1082 spin_lock_irq(&pwq
->pool
->lock
);
1084 spin_unlock_irq(&pwq
->pool
->lock
);
1088 static void pwq_activate_delayed_work(struct work_struct
*work
)
1090 struct pool_workqueue
*pwq
= get_work_pwq(work
);
1092 trace_workqueue_activate_work(work
);
1093 move_linked_works(work
, &pwq
->pool
->worklist
, NULL
);
1094 __clear_bit(WORK_STRUCT_DELAYED_BIT
, work_data_bits(work
));
1098 static void pwq_activate_first_delayed(struct pool_workqueue
*pwq
)
1100 struct work_struct
*work
= list_first_entry(&pwq
->delayed_works
,
1101 struct work_struct
, entry
);
1103 pwq_activate_delayed_work(work
);
1107 * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
1108 * @pwq: pwq of interest
1109 * @color: color of work which left the queue
1111 * A work either has completed or is removed from pending queue,
1112 * decrement nr_in_flight of its pwq and handle workqueue flushing.
1115 * spin_lock_irq(pool->lock).
1117 static void pwq_dec_nr_in_flight(struct pool_workqueue
*pwq
, int color
)
1119 /* uncolored work items don't participate in flushing or nr_active */
1120 if (color
== WORK_NO_COLOR
)
1123 pwq
->nr_in_flight
[color
]--;
1126 if (!list_empty(&pwq
->delayed_works
)) {
1127 /* one down, submit a delayed one */
1128 if (pwq
->nr_active
< pwq
->max_active
)
1129 pwq_activate_first_delayed(pwq
);
1132 /* is flush in progress and are we at the flushing tip? */
1133 if (likely(pwq
->flush_color
!= color
))
1136 /* are there still in-flight works? */
1137 if (pwq
->nr_in_flight
[color
])
1140 /* this pwq is done, clear flush_color */
1141 pwq
->flush_color
= -1;
1144 * If this was the last pwq, wake up the first flusher. It
1145 * will handle the rest.
1147 if (atomic_dec_and_test(&pwq
->wq
->nr_pwqs_to_flush
))
1148 complete(&pwq
->wq
->first_flusher
->done
);
1154 * try_to_grab_pending - steal work item from worklist and disable irq
1155 * @work: work item to steal
1156 * @is_dwork: @work is a delayed_work
1157 * @flags: place to store irq state
1159 * Try to grab PENDING bit of @work. This function can handle @work in any
1160 * stable state - idle, on timer or on worklist.
1163 * 1 if @work was pending and we successfully stole PENDING
1164 * 0 if @work was idle and we claimed PENDING
1165 * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
1166 * -ENOENT if someone else is canceling @work, this state may persist
1167 * for arbitrarily long
1170 * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
1171 * interrupted while holding PENDING and @work off queue, irq must be
1172 * disabled on entry. This, combined with delayed_work->timer being
1173 * irqsafe, ensures that we return -EAGAIN for finite short period of time.
1175 * On successful return, >= 0, irq is disabled and the caller is
1176 * responsible for releasing it using local_irq_restore(*@flags).
1178 * This function is safe to call from any context including IRQ handler.
1180 static int try_to_grab_pending(struct work_struct
*work
, bool is_dwork
,
1181 unsigned long *flags
)
1183 struct worker_pool
*pool
;
1184 struct pool_workqueue
*pwq
;
1186 local_irq_save(*flags
);
1188 /* try to steal the timer if it exists */
1190 struct delayed_work
*dwork
= to_delayed_work(work
);
1193 * dwork->timer is irqsafe. If del_timer() fails, it's
1194 * guaranteed that the timer is not queued anywhere and not
1195 * running on the local CPU.
1197 if (likely(del_timer(&dwork
->timer
)))
1201 /* try to claim PENDING the normal way */
1202 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
)))
1206 * The queueing is in progress, or it is already queued. Try to
1207 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
1209 pool
= get_work_pool(work
);
1213 spin_lock(&pool
->lock
);
1215 * work->data is guaranteed to point to pwq only while the work
1216 * item is queued on pwq->wq, and both updating work->data to point
1217 * to pwq on queueing and to pool on dequeueing are done under
1218 * pwq->pool->lock. This in turn guarantees that, if work->data
1219 * points to pwq which is associated with a locked pool, the work
1220 * item is currently queued on that pool.
1222 pwq
= get_work_pwq(work
);
1223 if (pwq
&& pwq
->pool
== pool
) {
1224 debug_work_deactivate(work
);
1227 * A delayed work item cannot be grabbed directly because
1228 * it might have linked NO_COLOR work items which, if left
1229 * on the delayed_list, will confuse pwq->nr_active
1230 * management later on and cause stall. Make sure the work
1231 * item is activated before grabbing.
1233 if (*work_data_bits(work
) & WORK_STRUCT_DELAYED
)
1234 pwq_activate_delayed_work(work
);
1236 list_del_init(&work
->entry
);
1237 pwq_dec_nr_in_flight(pwq
, get_work_color(work
));
1239 /* work->data points to pwq iff queued, point to pool */
1240 set_work_pool_and_keep_pending(work
, pool
->id
);
1242 spin_unlock(&pool
->lock
);
1245 spin_unlock(&pool
->lock
);
1247 local_irq_restore(*flags
);
1248 if (work_is_canceling(work
))
1255 * insert_work - insert a work into a pool
1256 * @pwq: pwq @work belongs to
1257 * @work: work to insert
1258 * @head: insertion point
1259 * @extra_flags: extra WORK_STRUCT_* flags to set
1261 * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
1262 * work_struct flags.
1265 * spin_lock_irq(pool->lock).
1267 static void insert_work(struct pool_workqueue
*pwq
, struct work_struct
*work
,
1268 struct list_head
*head
, unsigned int extra_flags
)
1270 struct worker_pool
*pool
= pwq
->pool
;
1272 /* we own @work, set data and link */
1273 set_work_pwq(work
, pwq
, extra_flags
);
1274 list_add_tail(&work
->entry
, head
);
1278 * Ensure either wq_worker_sleeping() sees the above
1279 * list_add_tail() or we see zero nr_running to avoid workers lying
1280 * around lazily while there are works to be processed.
1284 if (__need_more_worker(pool
))
1285 wake_up_worker(pool
);
1289 * Test whether @work is being queued from another work executing on the
1292 static bool is_chained_work(struct workqueue_struct
*wq
)
1294 struct worker
*worker
;
1296 worker
= current_wq_worker();
1298 * Return %true iff I'm a worker execuing a work item on @wq. If
1299 * I'm @worker, it's safe to dereference it without locking.
1301 return worker
&& worker
->current_pwq
->wq
== wq
;
1304 static void __queue_work(int cpu
, struct workqueue_struct
*wq
,
1305 struct work_struct
*work
)
1307 struct pool_workqueue
*pwq
;
1308 struct worker_pool
*last_pool
;
1309 struct list_head
*worklist
;
1310 unsigned int work_flags
;
1311 unsigned int req_cpu
= cpu
;
1314 * While a work item is PENDING && off queue, a task trying to
1315 * steal the PENDING will busy-loop waiting for it to either get
1316 * queued or lose PENDING. Grabbing PENDING and queueing should
1317 * happen with IRQ disabled.
1319 WARN_ON_ONCE(!irqs_disabled());
1321 debug_work_activate(work
);
1323 /* if draining, only works from the same workqueue are allowed */
1324 if (unlikely(wq
->flags
& __WQ_DRAINING
) &&
1325 WARN_ON_ONCE(!is_chained_work(wq
)))
1328 if (req_cpu
== WORK_CPU_UNBOUND
)
1329 cpu
= raw_smp_processor_id();
1331 /* pwq which will be used unless @work is executing elsewhere */
1332 if (!(wq
->flags
& WQ_UNBOUND
))
1333 pwq
= per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
1335 pwq
= unbound_pwq_by_node(wq
, cpu_to_node(cpu
));
1338 * If @work was previously on a different pool, it might still be
1339 * running there, in which case the work needs to be queued on that
1340 * pool to guarantee non-reentrancy.
1342 last_pool
= get_work_pool(work
);
1343 if (last_pool
&& last_pool
!= pwq
->pool
) {
1344 struct worker
*worker
;
1346 spin_lock(&last_pool
->lock
);
1348 worker
= find_worker_executing_work(last_pool
, work
);
1350 if (worker
&& worker
->current_pwq
->wq
== wq
) {
1351 pwq
= worker
->current_pwq
;
1353 /* meh... not running there, queue here */
1354 spin_unlock(&last_pool
->lock
);
1355 spin_lock(&pwq
->pool
->lock
);
1358 spin_lock(&pwq
->pool
->lock
);
1362 * pwq is determined and locked. For unbound pools, we could have
1363 * raced with pwq release and it could already be dead. If its
1364 * refcnt is zero, repeat pwq selection. Note that pwqs never die
1365 * without another pwq replacing it in the numa_pwq_tbl or while
1366 * work items are executing on it, so the retrying is guaranteed to
1367 * make forward-progress.
1369 if (unlikely(!pwq
->refcnt
)) {
1370 if (wq
->flags
& WQ_UNBOUND
) {
1371 spin_unlock(&pwq
->pool
->lock
);
1376 WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
1380 /* pwq determined, queue */
1381 trace_workqueue_queue_work(req_cpu
, pwq
, work
);
1383 if (WARN_ON(!list_empty(&work
->entry
))) {
1384 spin_unlock(&pwq
->pool
->lock
);
1388 pwq
->nr_in_flight
[pwq
->work_color
]++;
1389 work_flags
= work_color_to_flags(pwq
->work_color
);
1391 if (likely(pwq
->nr_active
< pwq
->max_active
)) {
1392 trace_workqueue_activate_work(work
);
1394 worklist
= &pwq
->pool
->worklist
;
1396 work_flags
|= WORK_STRUCT_DELAYED
;
1397 worklist
= &pwq
->delayed_works
;
1400 insert_work(pwq
, work
, worklist
, work_flags
);
1402 spin_unlock(&pwq
->pool
->lock
);
1406 * queue_work_on - queue work on specific cpu
1407 * @cpu: CPU number to execute work on
1408 * @wq: workqueue to use
1409 * @work: work to queue
1411 * We queue the work to a specific CPU, the caller must ensure it
1414 * Return: %false if @work was already on a queue, %true otherwise.
1416 bool queue_work_on(int cpu
, struct workqueue_struct
*wq
,
1417 struct work_struct
*work
)
1420 unsigned long flags
;
1422 local_irq_save(flags
);
1424 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1425 __queue_work(cpu
, wq
, work
);
1429 local_irq_restore(flags
);
1432 EXPORT_SYMBOL(queue_work_on
);
1434 void delayed_work_timer_fn(unsigned long __data
)
1436 struct delayed_work
*dwork
= (struct delayed_work
*)__data
;
1438 /* should have been called from irqsafe timer with irq already off */
1439 __queue_work(dwork
->cpu
, dwork
->wq
, &dwork
->work
);
1441 EXPORT_SYMBOL(delayed_work_timer_fn
);
1443 static void __queue_delayed_work(int cpu
, struct workqueue_struct
*wq
,
1444 struct delayed_work
*dwork
, unsigned long delay
)
1446 struct timer_list
*timer
= &dwork
->timer
;
1447 struct work_struct
*work
= &dwork
->work
;
1449 WARN_ON_ONCE(timer
->function
!= delayed_work_timer_fn
||
1450 timer
->data
!= (unsigned long)dwork
);
1451 WARN_ON_ONCE(timer_pending(timer
));
1452 WARN_ON_ONCE(!list_empty(&work
->entry
));
1455 * If @delay is 0, queue @dwork->work immediately. This is for
1456 * both optimization and correctness. The earliest @timer can
1457 * expire is on the closest next tick and delayed_work users depend
1458 * on that there's no such delay when @delay is 0.
1461 __queue_work(cpu
, wq
, &dwork
->work
);
1465 timer_stats_timer_set_start_info(&dwork
->timer
);
1469 timer
->expires
= jiffies
+ delay
;
1471 if (unlikely(cpu
!= WORK_CPU_UNBOUND
))
1472 add_timer_on(timer
, cpu
);
1478 * queue_delayed_work_on - queue work on specific CPU after delay
1479 * @cpu: CPU number to execute work on
1480 * @wq: workqueue to use
1481 * @dwork: work to queue
1482 * @delay: number of jiffies to wait before queueing
1484 * Return: %false if @work was already on a queue, %true otherwise. If
1485 * @delay is zero and @dwork is idle, it will be scheduled for immediate
1488 bool queue_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1489 struct delayed_work
*dwork
, unsigned long delay
)
1491 struct work_struct
*work
= &dwork
->work
;
1493 unsigned long flags
;
1495 /* read the comment in __queue_work() */
1496 local_irq_save(flags
);
1498 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1499 __queue_delayed_work(cpu
, wq
, dwork
, delay
);
1503 local_irq_restore(flags
);
1506 EXPORT_SYMBOL(queue_delayed_work_on
);
1509 * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
1510 * @cpu: CPU number to execute work on
1511 * @wq: workqueue to use
1512 * @dwork: work to queue
1513 * @delay: number of jiffies to wait before queueing
1515 * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
1516 * modify @dwork's timer so that it expires after @delay. If @delay is
1517 * zero, @work is guaranteed to be scheduled immediately regardless of its
1520 * Return: %false if @dwork was idle and queued, %true if @dwork was
1521 * pending and its timer was modified.
1523 * This function is safe to call from any context including IRQ handler.
1524 * See try_to_grab_pending() for details.
1526 bool mod_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1527 struct delayed_work
*dwork
, unsigned long delay
)
1529 unsigned long flags
;
1533 ret
= try_to_grab_pending(&dwork
->work
, true, &flags
);
1534 } while (unlikely(ret
== -EAGAIN
));
1536 if (likely(ret
>= 0)) {
1537 __queue_delayed_work(cpu
, wq
, dwork
, delay
);
1538 local_irq_restore(flags
);
1541 /* -ENOENT from try_to_grab_pending() becomes %true */
1544 EXPORT_SYMBOL_GPL(mod_delayed_work_on
);
1547 * worker_enter_idle - enter idle state
1548 * @worker: worker which is entering idle state
1550 * @worker is entering idle state. Update stats and idle timer if
1554 * spin_lock_irq(pool->lock).
1556 static void worker_enter_idle(struct worker
*worker
)
1558 struct worker_pool
*pool
= worker
->pool
;
1560 if (WARN_ON_ONCE(worker
->flags
& WORKER_IDLE
) ||
1561 WARN_ON_ONCE(!list_empty(&worker
->entry
) &&
1562 (worker
->hentry
.next
|| worker
->hentry
.pprev
)))
1565 /* can't use worker_set_flags(), also called from create_worker() */
1566 worker
->flags
|= WORKER_IDLE
;
1568 worker
->last_active
= jiffies
;
1570 /* idle_list is LIFO */
1571 list_add(&worker
->entry
, &pool
->idle_list
);
1573 if (too_many_workers(pool
) && !timer_pending(&pool
->idle_timer
))
1574 mod_timer(&pool
->idle_timer
, jiffies
+ IDLE_WORKER_TIMEOUT
);
1577 * Sanity check nr_running. Because wq_unbind_fn() releases
1578 * pool->lock between setting %WORKER_UNBOUND and zapping
1579 * nr_running, the warning may trigger spuriously. Check iff
1580 * unbind is not in progress.
1582 WARN_ON_ONCE(!(pool
->flags
& POOL_DISASSOCIATED
) &&
1583 pool
->nr_workers
== pool
->nr_idle
&&
1584 atomic_read(&pool
->nr_running
));
1588 * worker_leave_idle - leave idle state
1589 * @worker: worker which is leaving idle state
1591 * @worker is leaving idle state. Update stats.
1594 * spin_lock_irq(pool->lock).
1596 static void worker_leave_idle(struct worker
*worker
)
1598 struct worker_pool
*pool
= worker
->pool
;
1600 if (WARN_ON_ONCE(!(worker
->flags
& WORKER_IDLE
)))
1602 worker_clr_flags(worker
, WORKER_IDLE
);
1604 list_del_init(&worker
->entry
);
1607 static struct worker
*alloc_worker(int node
)
1609 struct worker
*worker
;
1611 worker
= kzalloc_node(sizeof(*worker
), GFP_KERNEL
, node
);
1613 INIT_LIST_HEAD(&worker
->entry
);
1614 INIT_LIST_HEAD(&worker
->scheduled
);
1615 INIT_LIST_HEAD(&worker
->node
);
1616 /* on creation a worker is in !idle && prep state */
1617 worker
->flags
= WORKER_PREP
;
1623 * worker_attach_to_pool() - attach a worker to a pool
1624 * @worker: worker to be attached
1625 * @pool: the target pool
1627 * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and
1628 * cpu-binding of @worker are kept coordinated with the pool across
1631 static void worker_attach_to_pool(struct worker
*worker
,
1632 struct worker_pool
*pool
)
1634 mutex_lock(&pool
->attach_mutex
);
1637 * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
1638 * online CPUs. It'll be re-applied when any of the CPUs come up.
1640 set_cpus_allowed_ptr(worker
->task
, pool
->attrs
->cpumask
);
1643 * The pool->attach_mutex ensures %POOL_DISASSOCIATED remains
1644 * stable across this function. See the comments above the
1645 * flag definition for details.
1647 if (pool
->flags
& POOL_DISASSOCIATED
)
1648 worker
->flags
|= WORKER_UNBOUND
;
1650 list_add_tail(&worker
->node
, &pool
->workers
);
1652 mutex_unlock(&pool
->attach_mutex
);
1656 * worker_detach_from_pool() - detach a worker from its pool
1657 * @worker: worker which is attached to its pool
1658 * @pool: the pool @worker is attached to
1660 * Undo the attaching which had been done in worker_attach_to_pool(). The
1661 * caller worker shouldn't access to the pool after detached except it has
1662 * other reference to the pool.
1664 static void worker_detach_from_pool(struct worker
*worker
,
1665 struct worker_pool
*pool
)
1667 struct completion
*detach_completion
= NULL
;
1669 mutex_lock(&pool
->attach_mutex
);
1670 list_del(&worker
->node
);
1671 if (list_empty(&pool
->workers
))
1672 detach_completion
= pool
->detach_completion
;
1673 mutex_unlock(&pool
->attach_mutex
);
1675 /* clear leftover flags without pool->lock after it is detached */
1676 worker
->flags
&= ~(WORKER_UNBOUND
| WORKER_REBOUND
);
1678 if (detach_completion
)
1679 complete(detach_completion
);
1683 * create_worker - create a new workqueue worker
1684 * @pool: pool the new worker will belong to
1686 * Create and start a new worker which is attached to @pool.
1689 * Might sleep. Does GFP_KERNEL allocations.
1692 * Pointer to the newly created worker.
1694 static struct worker
*create_worker(struct worker_pool
*pool
)
1696 struct worker
*worker
= NULL
;
1700 /* ID is needed to determine kthread name */
1701 id
= ida_simple_get(&pool
->worker_ida
, 0, 0, GFP_KERNEL
);
1705 worker
= alloc_worker(pool
->node
);
1709 worker
->pool
= pool
;
1713 snprintf(id_buf
, sizeof(id_buf
), "%d:%d%s", pool
->cpu
, id
,
1714 pool
->attrs
->nice
< 0 ? "H" : "");
1716 snprintf(id_buf
, sizeof(id_buf
), "u%d:%d", pool
->id
, id
);
1718 worker
->task
= kthread_create_on_node(worker_thread
, worker
, pool
->node
,
1719 "kworker/%s", id_buf
);
1720 if (IS_ERR(worker
->task
))
1723 set_user_nice(worker
->task
, pool
->attrs
->nice
);
1725 /* prevent userland from meddling with cpumask of workqueue workers */
1726 worker
->task
->flags
|= PF_NO_SETAFFINITY
;
1728 /* successful, attach the worker to the pool */
1729 worker_attach_to_pool(worker
, pool
);
1731 /* start the newly created worker */
1732 spin_lock_irq(&pool
->lock
);
1733 worker
->pool
->nr_workers
++;
1734 worker_enter_idle(worker
);
1735 wake_up_process(worker
->task
);
1736 spin_unlock_irq(&pool
->lock
);
1742 ida_simple_remove(&pool
->worker_ida
, id
);
1748 * destroy_worker - destroy a workqueue worker
1749 * @worker: worker to be destroyed
1751 * Destroy @worker and adjust @pool stats accordingly. The worker should
1755 * spin_lock_irq(pool->lock).
1757 static void destroy_worker(struct worker
*worker
)
1759 struct worker_pool
*pool
= worker
->pool
;
1761 lockdep_assert_held(&pool
->lock
);
1763 /* sanity check frenzy */
1764 if (WARN_ON(worker
->current_work
) ||
1765 WARN_ON(!list_empty(&worker
->scheduled
)) ||
1766 WARN_ON(!(worker
->flags
& WORKER_IDLE
)))
1772 list_del_init(&worker
->entry
);
1773 worker
->flags
|= WORKER_DIE
;
1774 wake_up_process(worker
->task
);
1777 static void idle_worker_timeout(unsigned long __pool
)
1779 struct worker_pool
*pool
= (void *)__pool
;
1781 spin_lock_irq(&pool
->lock
);
1783 while (too_many_workers(pool
)) {
1784 struct worker
*worker
;
1785 unsigned long expires
;
1787 /* idle_list is kept in LIFO order, check the last one */
1788 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
1789 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
1791 if (time_before(jiffies
, expires
)) {
1792 mod_timer(&pool
->idle_timer
, expires
);
1796 destroy_worker(worker
);
1799 spin_unlock_irq(&pool
->lock
);
1802 static void send_mayday(struct work_struct
*work
)
1804 struct pool_workqueue
*pwq
= get_work_pwq(work
);
1805 struct workqueue_struct
*wq
= pwq
->wq
;
1807 lockdep_assert_held(&wq_mayday_lock
);
1812 /* mayday mayday mayday */
1813 if (list_empty(&pwq
->mayday_node
)) {
1815 * If @pwq is for an unbound wq, its base ref may be put at
1816 * any time due to an attribute change. Pin @pwq until the
1817 * rescuer is done with it.
1820 list_add_tail(&pwq
->mayday_node
, &wq
->maydays
);
1821 wake_up_process(wq
->rescuer
->task
);
1825 static void pool_mayday_timeout(unsigned long __pool
)
1827 struct worker_pool
*pool
= (void *)__pool
;
1828 struct work_struct
*work
;
1830 spin_lock_irq(&pool
->lock
);
1831 spin_lock(&wq_mayday_lock
); /* for wq->maydays */
1833 if (need_to_create_worker(pool
)) {
1835 * We've been trying to create a new worker but
1836 * haven't been successful. We might be hitting an
1837 * allocation deadlock. Send distress signals to
1840 list_for_each_entry(work
, &pool
->worklist
, entry
)
1844 spin_unlock(&wq_mayday_lock
);
1845 spin_unlock_irq(&pool
->lock
);
1847 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INTERVAL
);
1851 * maybe_create_worker - create a new worker if necessary
1852 * @pool: pool to create a new worker for
1854 * Create a new worker for @pool if necessary. @pool is guaranteed to
1855 * have at least one idle worker on return from this function. If
1856 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1857 * sent to all rescuers with works scheduled on @pool to resolve
1858 * possible allocation deadlock.
1860 * On return, need_to_create_worker() is guaranteed to be %false and
1861 * may_start_working() %true.
1864 * spin_lock_irq(pool->lock) which may be released and regrabbed
1865 * multiple times. Does GFP_KERNEL allocations. Called only from
1868 static void maybe_create_worker(struct worker_pool
*pool
)
1869 __releases(&pool
->lock
)
1870 __acquires(&pool
->lock
)
1873 spin_unlock_irq(&pool
->lock
);
1875 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1876 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INITIAL_TIMEOUT
);
1879 if (create_worker(pool
) || !need_to_create_worker(pool
))
1882 schedule_timeout_interruptible(CREATE_COOLDOWN
);
1884 if (!need_to_create_worker(pool
))
1888 del_timer_sync(&pool
->mayday_timer
);
1889 spin_lock_irq(&pool
->lock
);
1891 * This is necessary even after a new worker was just successfully
1892 * created as @pool->lock was dropped and the new worker might have
1893 * already become busy.
1895 if (need_to_create_worker(pool
))
1900 * manage_workers - manage worker pool
1903 * Assume the manager role and manage the worker pool @worker belongs
1904 * to. At any given time, there can be only zero or one manager per
1905 * pool. The exclusion is handled automatically by this function.
1907 * The caller can safely start processing works on false return. On
1908 * true return, it's guaranteed that need_to_create_worker() is false
1909 * and may_start_working() is true.
1912 * spin_lock_irq(pool->lock) which may be released and regrabbed
1913 * multiple times. Does GFP_KERNEL allocations.
1916 * %false if the pool doesn't need management and the caller can safely
1917 * start processing works, %true if management function was performed and
1918 * the conditions that the caller verified before calling the function may
1919 * no longer be true.
1921 static bool manage_workers(struct worker
*worker
)
1923 struct worker_pool
*pool
= worker
->pool
;
1926 * Anyone who successfully grabs manager_arb wins the arbitration
1927 * and becomes the manager. mutex_trylock() on pool->manager_arb
1928 * failure while holding pool->lock reliably indicates that someone
1929 * else is managing the pool and the worker which failed trylock
1930 * can proceed to executing work items. This means that anyone
1931 * grabbing manager_arb is responsible for actually performing
1932 * manager duties. If manager_arb is grabbed and released without
1933 * actual management, the pool may stall indefinitely.
1935 if (!mutex_trylock(&pool
->manager_arb
))
1937 pool
->manager
= worker
;
1939 maybe_create_worker(pool
);
1941 pool
->manager
= NULL
;
1942 mutex_unlock(&pool
->manager_arb
);
1947 * process_one_work - process single work
1949 * @work: work to process
1951 * Process @work. This function contains all the logics necessary to
1952 * process a single work including synchronization against and
1953 * interaction with other workers on the same cpu, queueing and
1954 * flushing. As long as context requirement is met, any worker can
1955 * call this function to process a work.
1958 * spin_lock_irq(pool->lock) which is released and regrabbed.
1960 static void process_one_work(struct worker
*worker
, struct work_struct
*work
)
1961 __releases(&pool
->lock
)
1962 __acquires(&pool
->lock
)
1964 struct pool_workqueue
*pwq
= get_work_pwq(work
);
1965 struct worker_pool
*pool
= worker
->pool
;
1966 bool cpu_intensive
= pwq
->wq
->flags
& WQ_CPU_INTENSIVE
;
1968 struct worker
*collision
;
1969 #ifdef CONFIG_LOCKDEP
1971 * It is permissible to free the struct work_struct from
1972 * inside the function that is called from it, this we need to
1973 * take into account for lockdep too. To avoid bogus "held
1974 * lock freed" warnings as well as problems when looking into
1975 * work->lockdep_map, make a copy and use that here.
1977 struct lockdep_map lockdep_map
;
1979 lockdep_copy_map(&lockdep_map
, &work
->lockdep_map
);
1981 /* ensure we're on the correct CPU */
1982 WARN_ON_ONCE(!(pool
->flags
& POOL_DISASSOCIATED
) &&
1983 raw_smp_processor_id() != pool
->cpu
);
1986 * A single work shouldn't be executed concurrently by
1987 * multiple workers on a single cpu. Check whether anyone is
1988 * already processing the work. If so, defer the work to the
1989 * currently executing one.
1991 collision
= find_worker_executing_work(pool
, work
);
1992 if (unlikely(collision
)) {
1993 move_linked_works(work
, &collision
->scheduled
, NULL
);
1997 /* claim and dequeue */
1998 debug_work_deactivate(work
);
1999 hash_add(pool
->busy_hash
, &worker
->hentry
, (unsigned long)work
);
2000 worker
->current_work
= work
;
2001 worker
->current_func
= work
->func
;
2002 worker
->current_pwq
= pwq
;
2003 work_color
= get_work_color(work
);
2005 list_del_init(&work
->entry
);
2008 * CPU intensive works don't participate in concurrency management.
2009 * They're the scheduler's responsibility. This takes @worker out
2010 * of concurrency management and the next code block will chain
2011 * execution of the pending work items.
2013 if (unlikely(cpu_intensive
))
2014 worker_set_flags(worker
, WORKER_CPU_INTENSIVE
);
2017 * Wake up another worker if necessary. The condition is always
2018 * false for normal per-cpu workers since nr_running would always
2019 * be >= 1 at this point. This is used to chain execution of the
2020 * pending work items for WORKER_NOT_RUNNING workers such as the
2021 * UNBOUND and CPU_INTENSIVE ones.
2023 if (need_more_worker(pool
))
2024 wake_up_worker(pool
);
2027 * Record the last pool and clear PENDING which should be the last
2028 * update to @work. Also, do this inside @pool->lock so that
2029 * PENDING and queued state changes happen together while IRQ is
2032 set_work_pool_and_clear_pending(work
, pool
->id
);
2034 spin_unlock_irq(&pool
->lock
);
2036 lock_map_acquire_read(&pwq
->wq
->lockdep_map
);
2037 lock_map_acquire(&lockdep_map
);
2038 trace_workqueue_execute_start(work
);
2039 worker
->current_func(work
);
2041 * While we must be careful to not use "work" after this, the trace
2042 * point will only record its address.
2044 trace_workqueue_execute_end(work
);
2045 lock_map_release(&lockdep_map
);
2046 lock_map_release(&pwq
->wq
->lockdep_map
);
2048 if (unlikely(in_atomic() || lockdep_depth(current
) > 0)) {
2049 pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
2050 " last function: %pf\n",
2051 current
->comm
, preempt_count(), task_pid_nr(current
),
2052 worker
->current_func
);
2053 debug_show_held_locks(current
);
2058 * The following prevents a kworker from hogging CPU on !PREEMPT
2059 * kernels, where a requeueing work item waiting for something to
2060 * happen could deadlock with stop_machine as such work item could
2061 * indefinitely requeue itself while all other CPUs are trapped in
2062 * stop_machine. At the same time, report a quiescent RCU state so
2063 * the same condition doesn't freeze RCU.
2065 cond_resched_rcu_qs();
2067 spin_lock_irq(&pool
->lock
);
2069 /* clear cpu intensive status */
2070 if (unlikely(cpu_intensive
))
2071 worker_clr_flags(worker
, WORKER_CPU_INTENSIVE
);
2073 /* we're done with it, release */
2074 hash_del(&worker
->hentry
);
2075 worker
->current_work
= NULL
;
2076 worker
->current_func
= NULL
;
2077 worker
->current_pwq
= NULL
;
2078 worker
->desc_valid
= false;
2079 pwq_dec_nr_in_flight(pwq
, work_color
);
2083 * process_scheduled_works - process scheduled works
2086 * Process all scheduled works. Please note that the scheduled list
2087 * may change while processing a work, so this function repeatedly
2088 * fetches a work from the top and executes it.
2091 * spin_lock_irq(pool->lock) which may be released and regrabbed
2094 static void process_scheduled_works(struct worker
*worker
)
2096 while (!list_empty(&worker
->scheduled
)) {
2097 struct work_struct
*work
= list_first_entry(&worker
->scheduled
,
2098 struct work_struct
, entry
);
2099 process_one_work(worker
, work
);
2104 * worker_thread - the worker thread function
2107 * The worker thread function. All workers belong to a worker_pool -
2108 * either a per-cpu one or dynamic unbound one. These workers process all
2109 * work items regardless of their specific target workqueue. The only
2110 * exception is work items which belong to workqueues with a rescuer which
2111 * will be explained in rescuer_thread().
2115 static int worker_thread(void *__worker
)
2117 struct worker
*worker
= __worker
;
2118 struct worker_pool
*pool
= worker
->pool
;
2120 /* tell the scheduler that this is a workqueue worker */
2121 worker
->task
->flags
|= PF_WQ_WORKER
;
2123 spin_lock_irq(&pool
->lock
);
2125 /* am I supposed to die? */
2126 if (unlikely(worker
->flags
& WORKER_DIE
)) {
2127 spin_unlock_irq(&pool
->lock
);
2128 WARN_ON_ONCE(!list_empty(&worker
->entry
));
2129 worker
->task
->flags
&= ~PF_WQ_WORKER
;
2131 set_task_comm(worker
->task
, "kworker/dying");
2132 ida_simple_remove(&pool
->worker_ida
, worker
->id
);
2133 worker_detach_from_pool(worker
, pool
);
2138 worker_leave_idle(worker
);
2140 /* no more worker necessary? */
2141 if (!need_more_worker(pool
))
2144 /* do we need to manage? */
2145 if (unlikely(!may_start_working(pool
)) && manage_workers(worker
))
2149 * ->scheduled list can only be filled while a worker is
2150 * preparing to process a work or actually processing it.
2151 * Make sure nobody diddled with it while I was sleeping.
2153 WARN_ON_ONCE(!list_empty(&worker
->scheduled
));
2156 * Finish PREP stage. We're guaranteed to have at least one idle
2157 * worker or that someone else has already assumed the manager
2158 * role. This is where @worker starts participating in concurrency
2159 * management if applicable and concurrency management is restored
2160 * after being rebound. See rebind_workers() for details.
2162 worker_clr_flags(worker
, WORKER_PREP
| WORKER_REBOUND
);
2165 struct work_struct
*work
=
2166 list_first_entry(&pool
->worklist
,
2167 struct work_struct
, entry
);
2169 if (likely(!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))) {
2170 /* optimization path, not strictly necessary */
2171 process_one_work(worker
, work
);
2172 if (unlikely(!list_empty(&worker
->scheduled
)))
2173 process_scheduled_works(worker
);
2175 move_linked_works(work
, &worker
->scheduled
, NULL
);
2176 process_scheduled_works(worker
);
2178 } while (keep_working(pool
));
2180 worker_set_flags(worker
, WORKER_PREP
);
2183 * pool->lock is held and there's no work to process and no need to
2184 * manage, sleep. Workers are woken up only while holding
2185 * pool->lock or from local cpu, so setting the current state
2186 * before releasing pool->lock is enough to prevent losing any
2189 worker_enter_idle(worker
);
2190 __set_current_state(TASK_INTERRUPTIBLE
);
2191 spin_unlock_irq(&pool
->lock
);
2197 * rescuer_thread - the rescuer thread function
2200 * Workqueue rescuer thread function. There's one rescuer for each
2201 * workqueue which has WQ_MEM_RECLAIM set.
2203 * Regular work processing on a pool may block trying to create a new
2204 * worker which uses GFP_KERNEL allocation which has slight chance of
2205 * developing into deadlock if some works currently on the same queue
2206 * need to be processed to satisfy the GFP_KERNEL allocation. This is
2207 * the problem rescuer solves.
2209 * When such condition is possible, the pool summons rescuers of all
2210 * workqueues which have works queued on the pool and let them process
2211 * those works so that forward progress can be guaranteed.
2213 * This should happen rarely.
2217 static int rescuer_thread(void *__rescuer
)
2219 struct worker
*rescuer
= __rescuer
;
2220 struct workqueue_struct
*wq
= rescuer
->rescue_wq
;
2221 struct list_head
*scheduled
= &rescuer
->scheduled
;
2224 set_user_nice(current
, RESCUER_NICE_LEVEL
);
2227 * Mark rescuer as worker too. As WORKER_PREP is never cleared, it
2228 * doesn't participate in concurrency management.
2230 rescuer
->task
->flags
|= PF_WQ_WORKER
;
2232 set_current_state(TASK_INTERRUPTIBLE
);
2235 * By the time the rescuer is requested to stop, the workqueue
2236 * shouldn't have any work pending, but @wq->maydays may still have
2237 * pwq(s) queued. This can happen by non-rescuer workers consuming
2238 * all the work items before the rescuer got to them. Go through
2239 * @wq->maydays processing before acting on should_stop so that the
2240 * list is always empty on exit.
2242 should_stop
= kthread_should_stop();
2244 /* see whether any pwq is asking for help */
2245 spin_lock_irq(&wq_mayday_lock
);
2247 while (!list_empty(&wq
->maydays
)) {
2248 struct pool_workqueue
*pwq
= list_first_entry(&wq
->maydays
,
2249 struct pool_workqueue
, mayday_node
);
2250 struct worker_pool
*pool
= pwq
->pool
;
2251 struct work_struct
*work
, *n
;
2253 __set_current_state(TASK_RUNNING
);
2254 list_del_init(&pwq
->mayday_node
);
2256 spin_unlock_irq(&wq_mayday_lock
);
2258 worker_attach_to_pool(rescuer
, pool
);
2260 spin_lock_irq(&pool
->lock
);
2261 rescuer
->pool
= pool
;
2264 * Slurp in all works issued via this workqueue and
2267 WARN_ON_ONCE(!list_empty(scheduled
));
2268 list_for_each_entry_safe(work
, n
, &pool
->worklist
, entry
)
2269 if (get_work_pwq(work
) == pwq
)
2270 move_linked_works(work
, scheduled
, &n
);
2272 if (!list_empty(scheduled
)) {
2273 process_scheduled_works(rescuer
);
2276 * The above execution of rescued work items could
2277 * have created more to rescue through
2278 * pwq_activate_first_delayed() or chained
2279 * queueing. Let's put @pwq back on mayday list so
2280 * that such back-to-back work items, which may be
2281 * being used to relieve memory pressure, don't
2282 * incur MAYDAY_INTERVAL delay inbetween.
2284 if (need_to_create_worker(pool
)) {
2285 spin_lock(&wq_mayday_lock
);
2287 list_move_tail(&pwq
->mayday_node
, &wq
->maydays
);
2288 spin_unlock(&wq_mayday_lock
);
2293 * Put the reference grabbed by send_mayday(). @pool won't
2294 * go away while we're still attached to it.
2299 * Leave this pool. If need_more_worker() is %true, notify a
2300 * regular worker; otherwise, we end up with 0 concurrency
2301 * and stalling the execution.
2303 if (need_more_worker(pool
))
2304 wake_up_worker(pool
);
2306 rescuer
->pool
= NULL
;
2307 spin_unlock_irq(&pool
->lock
);
2309 worker_detach_from_pool(rescuer
, pool
);
2311 spin_lock_irq(&wq_mayday_lock
);
2314 spin_unlock_irq(&wq_mayday_lock
);
2317 __set_current_state(TASK_RUNNING
);
2318 rescuer
->task
->flags
&= ~PF_WQ_WORKER
;
2322 /* rescuers should never participate in concurrency management */
2323 WARN_ON_ONCE(!(rescuer
->flags
& WORKER_NOT_RUNNING
));
2329 struct work_struct work
;
2330 struct completion done
;
2331 struct task_struct
*task
; /* purely informational */
2334 static void wq_barrier_func(struct work_struct
*work
)
2336 struct wq_barrier
*barr
= container_of(work
, struct wq_barrier
, work
);
2337 complete(&barr
->done
);
2341 * insert_wq_barrier - insert a barrier work
2342 * @pwq: pwq to insert barrier into
2343 * @barr: wq_barrier to insert
2344 * @target: target work to attach @barr to
2345 * @worker: worker currently executing @target, NULL if @target is not executing
2347 * @barr is linked to @target such that @barr is completed only after
2348 * @target finishes execution. Please note that the ordering
2349 * guarantee is observed only with respect to @target and on the local
2352 * Currently, a queued barrier can't be canceled. This is because
2353 * try_to_grab_pending() can't determine whether the work to be
2354 * grabbed is at the head of the queue and thus can't clear LINKED
2355 * flag of the previous work while there must be a valid next work
2356 * after a work with LINKED flag set.
2358 * Note that when @worker is non-NULL, @target may be modified
2359 * underneath us, so we can't reliably determine pwq from @target.
2362 * spin_lock_irq(pool->lock).
2364 static void insert_wq_barrier(struct pool_workqueue
*pwq
,
2365 struct wq_barrier
*barr
,
2366 struct work_struct
*target
, struct worker
*worker
)
2368 struct list_head
*head
;
2369 unsigned int linked
= 0;
2372 * debugobject calls are safe here even with pool->lock locked
2373 * as we know for sure that this will not trigger any of the
2374 * checks and call back into the fixup functions where we
2377 INIT_WORK_ONSTACK(&barr
->work
, wq_barrier_func
);
2378 __set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(&barr
->work
));
2379 init_completion(&barr
->done
);
2380 barr
->task
= current
;
2383 * If @target is currently being executed, schedule the
2384 * barrier to the worker; otherwise, put it after @target.
2387 head
= worker
->scheduled
.next
;
2389 unsigned long *bits
= work_data_bits(target
);
2391 head
= target
->entry
.next
;
2392 /* there can already be other linked works, inherit and set */
2393 linked
= *bits
& WORK_STRUCT_LINKED
;
2394 __set_bit(WORK_STRUCT_LINKED_BIT
, bits
);
2397 debug_work_activate(&barr
->work
);
2398 insert_work(pwq
, &barr
->work
, head
,
2399 work_color_to_flags(WORK_NO_COLOR
) | linked
);
2403 * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
2404 * @wq: workqueue being flushed
2405 * @flush_color: new flush color, < 0 for no-op
2406 * @work_color: new work color, < 0 for no-op
2408 * Prepare pwqs for workqueue flushing.
2410 * If @flush_color is non-negative, flush_color on all pwqs should be
2411 * -1. If no pwq has in-flight commands at the specified color, all
2412 * pwq->flush_color's stay at -1 and %false is returned. If any pwq
2413 * has in flight commands, its pwq->flush_color is set to
2414 * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
2415 * wakeup logic is armed and %true is returned.
2417 * The caller should have initialized @wq->first_flusher prior to
2418 * calling this function with non-negative @flush_color. If
2419 * @flush_color is negative, no flush color update is done and %false
2422 * If @work_color is non-negative, all pwqs should have the same
2423 * work_color which is previous to @work_color and all will be
2424 * advanced to @work_color.
2427 * mutex_lock(wq->mutex).
2430 * %true if @flush_color >= 0 and there's something to flush. %false
2433 static bool flush_workqueue_prep_pwqs(struct workqueue_struct
*wq
,
2434 int flush_color
, int work_color
)
2437 struct pool_workqueue
*pwq
;
2439 if (flush_color
>= 0) {
2440 WARN_ON_ONCE(atomic_read(&wq
->nr_pwqs_to_flush
));
2441 atomic_set(&wq
->nr_pwqs_to_flush
, 1);
2444 for_each_pwq(pwq
, wq
) {
2445 struct worker_pool
*pool
= pwq
->pool
;
2447 spin_lock_irq(&pool
->lock
);
2449 if (flush_color
>= 0) {
2450 WARN_ON_ONCE(pwq
->flush_color
!= -1);
2452 if (pwq
->nr_in_flight
[flush_color
]) {
2453 pwq
->flush_color
= flush_color
;
2454 atomic_inc(&wq
->nr_pwqs_to_flush
);
2459 if (work_color
>= 0) {
2460 WARN_ON_ONCE(work_color
!= work_next_color(pwq
->work_color
));
2461 pwq
->work_color
= work_color
;
2464 spin_unlock_irq(&pool
->lock
);
2467 if (flush_color
>= 0 && atomic_dec_and_test(&wq
->nr_pwqs_to_flush
))
2468 complete(&wq
->first_flusher
->done
);
2474 * flush_workqueue - ensure that any scheduled work has run to completion.
2475 * @wq: workqueue to flush
2477 * This function sleeps until all work items which were queued on entry
2478 * have finished execution, but it is not livelocked by new incoming ones.
2480 void flush_workqueue(struct workqueue_struct
*wq
)
2482 struct wq_flusher this_flusher
= {
2483 .list
= LIST_HEAD_INIT(this_flusher
.list
),
2485 .done
= COMPLETION_INITIALIZER_ONSTACK(this_flusher
.done
),
2489 lock_map_acquire(&wq
->lockdep_map
);
2490 lock_map_release(&wq
->lockdep_map
);
2492 mutex_lock(&wq
->mutex
);
2495 * Start-to-wait phase
2497 next_color
= work_next_color(wq
->work_color
);
2499 if (next_color
!= wq
->flush_color
) {
2501 * Color space is not full. The current work_color
2502 * becomes our flush_color and work_color is advanced
2505 WARN_ON_ONCE(!list_empty(&wq
->flusher_overflow
));
2506 this_flusher
.flush_color
= wq
->work_color
;
2507 wq
->work_color
= next_color
;
2509 if (!wq
->first_flusher
) {
2510 /* no flush in progress, become the first flusher */
2511 WARN_ON_ONCE(wq
->flush_color
!= this_flusher
.flush_color
);
2513 wq
->first_flusher
= &this_flusher
;
2515 if (!flush_workqueue_prep_pwqs(wq
, wq
->flush_color
,
2517 /* nothing to flush, done */
2518 wq
->flush_color
= next_color
;
2519 wq
->first_flusher
= NULL
;
2524 WARN_ON_ONCE(wq
->flush_color
== this_flusher
.flush_color
);
2525 list_add_tail(&this_flusher
.list
, &wq
->flusher_queue
);
2526 flush_workqueue_prep_pwqs(wq
, -1, wq
->work_color
);
2530 * Oops, color space is full, wait on overflow queue.
2531 * The next flush completion will assign us
2532 * flush_color and transfer to flusher_queue.
2534 list_add_tail(&this_flusher
.list
, &wq
->flusher_overflow
);
2537 mutex_unlock(&wq
->mutex
);
2539 wait_for_completion(&this_flusher
.done
);
2542 * Wake-up-and-cascade phase
2544 * First flushers are responsible for cascading flushes and
2545 * handling overflow. Non-first flushers can simply return.
2547 if (wq
->first_flusher
!= &this_flusher
)
2550 mutex_lock(&wq
->mutex
);
2552 /* we might have raced, check again with mutex held */
2553 if (wq
->first_flusher
!= &this_flusher
)
2556 wq
->first_flusher
= NULL
;
2558 WARN_ON_ONCE(!list_empty(&this_flusher
.list
));
2559 WARN_ON_ONCE(wq
->flush_color
!= this_flusher
.flush_color
);
2562 struct wq_flusher
*next
, *tmp
;
2564 /* complete all the flushers sharing the current flush color */
2565 list_for_each_entry_safe(next
, tmp
, &wq
->flusher_queue
, list
) {
2566 if (next
->flush_color
!= wq
->flush_color
)
2568 list_del_init(&next
->list
);
2569 complete(&next
->done
);
2572 WARN_ON_ONCE(!list_empty(&wq
->flusher_overflow
) &&
2573 wq
->flush_color
!= work_next_color(wq
->work_color
));
2575 /* this flush_color is finished, advance by one */
2576 wq
->flush_color
= work_next_color(wq
->flush_color
);
2578 /* one color has been freed, handle overflow queue */
2579 if (!list_empty(&wq
->flusher_overflow
)) {
2581 * Assign the same color to all overflowed
2582 * flushers, advance work_color and append to
2583 * flusher_queue. This is the start-to-wait
2584 * phase for these overflowed flushers.
2586 list_for_each_entry(tmp
, &wq
->flusher_overflow
, list
)
2587 tmp
->flush_color
= wq
->work_color
;
2589 wq
->work_color
= work_next_color(wq
->work_color
);
2591 list_splice_tail_init(&wq
->flusher_overflow
,
2592 &wq
->flusher_queue
);
2593 flush_workqueue_prep_pwqs(wq
, -1, wq
->work_color
);
2596 if (list_empty(&wq
->flusher_queue
)) {
2597 WARN_ON_ONCE(wq
->flush_color
!= wq
->work_color
);
2602 * Need to flush more colors. Make the next flusher
2603 * the new first flusher and arm pwqs.
2605 WARN_ON_ONCE(wq
->flush_color
== wq
->work_color
);
2606 WARN_ON_ONCE(wq
->flush_color
!= next
->flush_color
);
2608 list_del_init(&next
->list
);
2609 wq
->first_flusher
= next
;
2611 if (flush_workqueue_prep_pwqs(wq
, wq
->flush_color
, -1))
2615 * Meh... this color is already done, clear first
2616 * flusher and repeat cascading.
2618 wq
->first_flusher
= NULL
;
2622 mutex_unlock(&wq
->mutex
);
2624 EXPORT_SYMBOL_GPL(flush_workqueue
);
2627 * drain_workqueue - drain a workqueue
2628 * @wq: workqueue to drain
2630 * Wait until the workqueue becomes empty. While draining is in progress,
2631 * only chain queueing is allowed. IOW, only currently pending or running
2632 * work items on @wq can queue further work items on it. @wq is flushed
2633 * repeatedly until it becomes empty. The number of flushing is determined
2634 * by the depth of chaining and should be relatively short. Whine if it
2637 void drain_workqueue(struct workqueue_struct
*wq
)
2639 unsigned int flush_cnt
= 0;
2640 struct pool_workqueue
*pwq
;
2643 * __queue_work() needs to test whether there are drainers, is much
2644 * hotter than drain_workqueue() and already looks at @wq->flags.
2645 * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
2647 mutex_lock(&wq
->mutex
);
2648 if (!wq
->nr_drainers
++)
2649 wq
->flags
|= __WQ_DRAINING
;
2650 mutex_unlock(&wq
->mutex
);
2652 flush_workqueue(wq
);
2654 mutex_lock(&wq
->mutex
);
2656 for_each_pwq(pwq
, wq
) {
2659 spin_lock_irq(&pwq
->pool
->lock
);
2660 drained
= !pwq
->nr_active
&& list_empty(&pwq
->delayed_works
);
2661 spin_unlock_irq(&pwq
->pool
->lock
);
2666 if (++flush_cnt
== 10 ||
2667 (flush_cnt
% 100 == 0 && flush_cnt
<= 1000))
2668 pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
2669 wq
->name
, flush_cnt
);
2671 mutex_unlock(&wq
->mutex
);
2675 if (!--wq
->nr_drainers
)
2676 wq
->flags
&= ~__WQ_DRAINING
;
2677 mutex_unlock(&wq
->mutex
);
2679 EXPORT_SYMBOL_GPL(drain_workqueue
);
2681 static bool start_flush_work(struct work_struct
*work
, struct wq_barrier
*barr
)
2683 struct worker
*worker
= NULL
;
2684 struct worker_pool
*pool
;
2685 struct pool_workqueue
*pwq
;
2689 local_irq_disable();
2690 pool
= get_work_pool(work
);
2696 spin_lock(&pool
->lock
);
2697 /* see the comment in try_to_grab_pending() with the same code */
2698 pwq
= get_work_pwq(work
);
2700 if (unlikely(pwq
->pool
!= pool
))
2703 worker
= find_worker_executing_work(pool
, work
);
2706 pwq
= worker
->current_pwq
;
2709 insert_wq_barrier(pwq
, barr
, work
, worker
);
2710 spin_unlock_irq(&pool
->lock
);
2713 * If @max_active is 1 or rescuer is in use, flushing another work
2714 * item on the same workqueue may lead to deadlock. Make sure the
2715 * flusher is not running on the same workqueue by verifying write
2718 if (pwq
->wq
->saved_max_active
== 1 || pwq
->wq
->rescuer
)
2719 lock_map_acquire(&pwq
->wq
->lockdep_map
);
2721 lock_map_acquire_read(&pwq
->wq
->lockdep_map
);
2722 lock_map_release(&pwq
->wq
->lockdep_map
);
2726 spin_unlock_irq(&pool
->lock
);
2731 * flush_work - wait for a work to finish executing the last queueing instance
2732 * @work: the work to flush
2734 * Wait until @work has finished execution. @work is guaranteed to be idle
2735 * on return if it hasn't been requeued since flush started.
2738 * %true if flush_work() waited for the work to finish execution,
2739 * %false if it was already idle.
2741 bool flush_work(struct work_struct
*work
)
2743 struct wq_barrier barr
;
2745 lock_map_acquire(&work
->lockdep_map
);
2746 lock_map_release(&work
->lockdep_map
);
2748 if (start_flush_work(work
, &barr
)) {
2749 wait_for_completion(&barr
.done
);
2750 destroy_work_on_stack(&barr
.work
);
2756 EXPORT_SYMBOL_GPL(flush_work
);
2760 struct work_struct
*work
;
2763 static int cwt_wakefn(wait_queue_t
*wait
, unsigned mode
, int sync
, void *key
)
2765 struct cwt_wait
*cwait
= container_of(wait
, struct cwt_wait
, wait
);
2767 if (cwait
->work
!= key
)
2769 return autoremove_wake_function(wait
, mode
, sync
, key
);
2772 static bool __cancel_work_timer(struct work_struct
*work
, bool is_dwork
)
2774 static DECLARE_WAIT_QUEUE_HEAD(cancel_waitq
);
2775 unsigned long flags
;
2779 ret
= try_to_grab_pending(work
, is_dwork
, &flags
);
2781 * If someone else is already canceling, wait for it to
2782 * finish. flush_work() doesn't work for PREEMPT_NONE
2783 * because we may get scheduled between @work's completion
2784 * and the other canceling task resuming and clearing
2785 * CANCELING - flush_work() will return false immediately
2786 * as @work is no longer busy, try_to_grab_pending() will
2787 * return -ENOENT as @work is still being canceled and the
2788 * other canceling task won't be able to clear CANCELING as
2789 * we're hogging the CPU.
2791 * Let's wait for completion using a waitqueue. As this
2792 * may lead to the thundering herd problem, use a custom
2793 * wake function which matches @work along with exclusive
2796 if (unlikely(ret
== -ENOENT
)) {
2797 struct cwt_wait cwait
;
2799 init_wait(&cwait
.wait
);
2800 cwait
.wait
.func
= cwt_wakefn
;
2803 prepare_to_wait_exclusive(&cancel_waitq
, &cwait
.wait
,
2804 TASK_UNINTERRUPTIBLE
);
2805 if (work_is_canceling(work
))
2807 finish_wait(&cancel_waitq
, &cwait
.wait
);
2809 } while (unlikely(ret
< 0));
2811 /* tell other tasks trying to grab @work to back off */
2812 mark_work_canceling(work
);
2813 local_irq_restore(flags
);
2816 clear_work_data(work
);
2819 * Paired with prepare_to_wait() above so that either
2820 * waitqueue_active() is visible here or !work_is_canceling() is
2824 if (waitqueue_active(&cancel_waitq
))
2825 __wake_up(&cancel_waitq
, TASK_NORMAL
, 1, work
);
2831 * cancel_work_sync - cancel a work and wait for it to finish
2832 * @work: the work to cancel
2834 * Cancel @work and wait for its execution to finish. This function
2835 * can be used even if the work re-queues itself or migrates to
2836 * another workqueue. On return from this function, @work is
2837 * guaranteed to be not pending or executing on any CPU.
2839 * cancel_work_sync(&delayed_work->work) must not be used for
2840 * delayed_work's. Use cancel_delayed_work_sync() instead.
2842 * The caller must ensure that the workqueue on which @work was last
2843 * queued can't be destroyed before this function returns.
2846 * %true if @work was pending, %false otherwise.
2848 bool cancel_work_sync(struct work_struct
*work
)
2850 return __cancel_work_timer(work
, false);
2852 EXPORT_SYMBOL_GPL(cancel_work_sync
);
2855 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2856 * @dwork: the delayed work to flush
2858 * Delayed timer is cancelled and the pending work is queued for
2859 * immediate execution. Like flush_work(), this function only
2860 * considers the last queueing instance of @dwork.
2863 * %true if flush_work() waited for the work to finish execution,
2864 * %false if it was already idle.
2866 bool flush_delayed_work(struct delayed_work
*dwork
)
2868 local_irq_disable();
2869 if (del_timer_sync(&dwork
->timer
))
2870 __queue_work(dwork
->cpu
, dwork
->wq
, &dwork
->work
);
2872 return flush_work(&dwork
->work
);
2874 EXPORT_SYMBOL(flush_delayed_work
);
2877 * cancel_delayed_work - cancel a delayed work
2878 * @dwork: delayed_work to cancel
2880 * Kill off a pending delayed_work.
2882 * Return: %true if @dwork was pending and canceled; %false if it wasn't
2886 * The work callback function may still be running on return, unless
2887 * it returns %true and the work doesn't re-arm itself. Explicitly flush or
2888 * use cancel_delayed_work_sync() to wait on it.
2890 * This function is safe to call from any context including IRQ handler.
2892 bool cancel_delayed_work(struct delayed_work
*dwork
)
2894 unsigned long flags
;
2898 ret
= try_to_grab_pending(&dwork
->work
, true, &flags
);
2899 } while (unlikely(ret
== -EAGAIN
));
2901 if (unlikely(ret
< 0))
2904 set_work_pool_and_clear_pending(&dwork
->work
,
2905 get_work_pool_id(&dwork
->work
));
2906 local_irq_restore(flags
);
2909 EXPORT_SYMBOL(cancel_delayed_work
);
2912 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
2913 * @dwork: the delayed work cancel
2915 * This is cancel_work_sync() for delayed works.
2918 * %true if @dwork was pending, %false otherwise.
2920 bool cancel_delayed_work_sync(struct delayed_work
*dwork
)
2922 return __cancel_work_timer(&dwork
->work
, true);
2924 EXPORT_SYMBOL(cancel_delayed_work_sync
);
2927 * schedule_on_each_cpu - execute a function synchronously on each online CPU
2928 * @func: the function to call
2930 * schedule_on_each_cpu() executes @func on each online CPU using the
2931 * system workqueue and blocks until all CPUs have completed.
2932 * schedule_on_each_cpu() is very slow.
2935 * 0 on success, -errno on failure.
2937 int schedule_on_each_cpu(work_func_t func
)
2940 struct work_struct __percpu
*works
;
2942 works
= alloc_percpu(struct work_struct
);
2948 for_each_online_cpu(cpu
) {
2949 struct work_struct
*work
= per_cpu_ptr(works
, cpu
);
2951 INIT_WORK(work
, func
);
2952 schedule_work_on(cpu
, work
);
2955 for_each_online_cpu(cpu
)
2956 flush_work(per_cpu_ptr(works
, cpu
));
2964 * flush_scheduled_work - ensure that any scheduled work has run to completion.
2966 * Forces execution of the kernel-global workqueue and blocks until its
2969 * Think twice before calling this function! It's very easy to get into
2970 * trouble if you don't take great care. Either of the following situations
2971 * will lead to deadlock:
2973 * One of the work items currently on the workqueue needs to acquire
2974 * a lock held by your code or its caller.
2976 * Your code is running in the context of a work routine.
2978 * They will be detected by lockdep when they occur, but the first might not
2979 * occur very often. It depends on what work items are on the workqueue and
2980 * what locks they need, which you have no control over.
2982 * In most situations flushing the entire workqueue is overkill; you merely
2983 * need to know that a particular work item isn't queued and isn't running.
2984 * In such cases you should use cancel_delayed_work_sync() or
2985 * cancel_work_sync() instead.
2987 void flush_scheduled_work(void)
2989 flush_workqueue(system_wq
);
2991 EXPORT_SYMBOL(flush_scheduled_work
);
2994 * execute_in_process_context - reliably execute the routine with user context
2995 * @fn: the function to execute
2996 * @ew: guaranteed storage for the execute work structure (must
2997 * be available when the work executes)
2999 * Executes the function immediately if process context is available,
3000 * otherwise schedules the function for delayed execution.
3002 * Return: 0 - function was executed
3003 * 1 - function was scheduled for execution
3005 int execute_in_process_context(work_func_t fn
, struct execute_work
*ew
)
3007 if (!in_interrupt()) {
3012 INIT_WORK(&ew
->work
, fn
);
3013 schedule_work(&ew
->work
);
3017 EXPORT_SYMBOL_GPL(execute_in_process_context
);
3020 * free_workqueue_attrs - free a workqueue_attrs
3021 * @attrs: workqueue_attrs to free
3023 * Undo alloc_workqueue_attrs().
3025 void free_workqueue_attrs(struct workqueue_attrs
*attrs
)
3028 free_cpumask_var(attrs
->cpumask
);
3034 * alloc_workqueue_attrs - allocate a workqueue_attrs
3035 * @gfp_mask: allocation mask to use
3037 * Allocate a new workqueue_attrs, initialize with default settings and
3040 * Return: The allocated new workqueue_attr on success. %NULL on failure.
3042 struct workqueue_attrs
*alloc_workqueue_attrs(gfp_t gfp_mask
)
3044 struct workqueue_attrs
*attrs
;
3046 attrs
= kzalloc(sizeof(*attrs
), gfp_mask
);
3049 if (!alloc_cpumask_var(&attrs
->cpumask
, gfp_mask
))
3052 cpumask_copy(attrs
->cpumask
, cpu_possible_mask
);
3055 free_workqueue_attrs(attrs
);
3059 static void copy_workqueue_attrs(struct workqueue_attrs
*to
,
3060 const struct workqueue_attrs
*from
)
3062 to
->nice
= from
->nice
;
3063 cpumask_copy(to
->cpumask
, from
->cpumask
);
3065 * Unlike hash and equality test, this function doesn't ignore
3066 * ->no_numa as it is used for both pool and wq attrs. Instead,
3067 * get_unbound_pool() explicitly clears ->no_numa after copying.
3069 to
->no_numa
= from
->no_numa
;
3072 /* hash value of the content of @attr */
3073 static u32
wqattrs_hash(const struct workqueue_attrs
*attrs
)
3077 hash
= jhash_1word(attrs
->nice
, hash
);
3078 hash
= jhash(cpumask_bits(attrs
->cpumask
),
3079 BITS_TO_LONGS(nr_cpumask_bits
) * sizeof(long), hash
);
3083 /* content equality test */
3084 static bool wqattrs_equal(const struct workqueue_attrs
*a
,
3085 const struct workqueue_attrs
*b
)
3087 if (a
->nice
!= b
->nice
)
3089 if (!cpumask_equal(a
->cpumask
, b
->cpumask
))
3095 * init_worker_pool - initialize a newly zalloc'd worker_pool
3096 * @pool: worker_pool to initialize
3098 * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs.
3100 * Return: 0 on success, -errno on failure. Even on failure, all fields
3101 * inside @pool proper are initialized and put_unbound_pool() can be called
3102 * on @pool safely to release it.
3104 static int init_worker_pool(struct worker_pool
*pool
)
3106 spin_lock_init(&pool
->lock
);
3109 pool
->node
= NUMA_NO_NODE
;
3110 pool
->flags
|= POOL_DISASSOCIATED
;
3111 INIT_LIST_HEAD(&pool
->worklist
);
3112 INIT_LIST_HEAD(&pool
->idle_list
);
3113 hash_init(pool
->busy_hash
);
3115 init_timer_deferrable(&pool
->idle_timer
);
3116 pool
->idle_timer
.function
= idle_worker_timeout
;
3117 pool
->idle_timer
.data
= (unsigned long)pool
;
3119 setup_timer(&pool
->mayday_timer
, pool_mayday_timeout
,
3120 (unsigned long)pool
);
3122 mutex_init(&pool
->manager_arb
);
3123 mutex_init(&pool
->attach_mutex
);
3124 INIT_LIST_HEAD(&pool
->workers
);
3126 ida_init(&pool
->worker_ida
);
3127 INIT_HLIST_NODE(&pool
->hash_node
);
3130 /* shouldn't fail above this point */
3131 pool
->attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3137 static void rcu_free_wq(struct rcu_head
*rcu
)
3139 struct workqueue_struct
*wq
=
3140 container_of(rcu
, struct workqueue_struct
, rcu
);
3142 if (!(wq
->flags
& WQ_UNBOUND
))
3143 free_percpu(wq
->cpu_pwqs
);
3145 free_workqueue_attrs(wq
->unbound_attrs
);
3151 static void rcu_free_pool(struct rcu_head
*rcu
)
3153 struct worker_pool
*pool
= container_of(rcu
, struct worker_pool
, rcu
);
3155 ida_destroy(&pool
->worker_ida
);
3156 free_workqueue_attrs(pool
->attrs
);
3161 * put_unbound_pool - put a worker_pool
3162 * @pool: worker_pool to put
3164 * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU
3165 * safe manner. get_unbound_pool() calls this function on its failure path
3166 * and this function should be able to release pools which went through,
3167 * successfully or not, init_worker_pool().
3169 * Should be called with wq_pool_mutex held.
3171 static void put_unbound_pool(struct worker_pool
*pool
)
3173 DECLARE_COMPLETION_ONSTACK(detach_completion
);
3174 struct worker
*worker
;
3176 lockdep_assert_held(&wq_pool_mutex
);
3182 if (WARN_ON(!(pool
->cpu
< 0)) ||
3183 WARN_ON(!list_empty(&pool
->worklist
)))
3186 /* release id and unhash */
3188 idr_remove(&worker_pool_idr
, pool
->id
);
3189 hash_del(&pool
->hash_node
);
3192 * Become the manager and destroy all workers. Grabbing
3193 * manager_arb prevents @pool's workers from blocking on
3196 mutex_lock(&pool
->manager_arb
);
3198 spin_lock_irq(&pool
->lock
);
3199 while ((worker
= first_idle_worker(pool
)))
3200 destroy_worker(worker
);
3201 WARN_ON(pool
->nr_workers
|| pool
->nr_idle
);
3202 spin_unlock_irq(&pool
->lock
);
3204 mutex_lock(&pool
->attach_mutex
);
3205 if (!list_empty(&pool
->workers
))
3206 pool
->detach_completion
= &detach_completion
;
3207 mutex_unlock(&pool
->attach_mutex
);
3209 if (pool
->detach_completion
)
3210 wait_for_completion(pool
->detach_completion
);
3212 mutex_unlock(&pool
->manager_arb
);
3214 /* shut down the timers */
3215 del_timer_sync(&pool
->idle_timer
);
3216 del_timer_sync(&pool
->mayday_timer
);
3218 /* sched-RCU protected to allow dereferences from get_work_pool() */
3219 call_rcu_sched(&pool
->rcu
, rcu_free_pool
);
3223 * get_unbound_pool - get a worker_pool with the specified attributes
3224 * @attrs: the attributes of the worker_pool to get
3226 * Obtain a worker_pool which has the same attributes as @attrs, bump the
3227 * reference count and return it. If there already is a matching
3228 * worker_pool, it will be used; otherwise, this function attempts to
3231 * Should be called with wq_pool_mutex held.
3233 * Return: On success, a worker_pool with the same attributes as @attrs.
3234 * On failure, %NULL.
3236 static struct worker_pool
*get_unbound_pool(const struct workqueue_attrs
*attrs
)
3238 u32 hash
= wqattrs_hash(attrs
);
3239 struct worker_pool
*pool
;
3242 lockdep_assert_held(&wq_pool_mutex
);
3244 /* do we already have a matching pool? */
3245 hash_for_each_possible(unbound_pool_hash
, pool
, hash_node
, hash
) {
3246 if (wqattrs_equal(pool
->attrs
, attrs
)) {
3252 /* nope, create a new one */
3253 pool
= kzalloc(sizeof(*pool
), GFP_KERNEL
);
3254 if (!pool
|| init_worker_pool(pool
) < 0)
3257 lockdep_set_subclass(&pool
->lock
, 1); /* see put_pwq() */
3258 copy_workqueue_attrs(pool
->attrs
, attrs
);
3261 * no_numa isn't a worker_pool attribute, always clear it. See
3262 * 'struct workqueue_attrs' comments for detail.
3264 pool
->attrs
->no_numa
= false;
3266 /* if cpumask is contained inside a NUMA node, we belong to that node */
3267 if (wq_numa_enabled
) {
3268 for_each_node(node
) {
3269 if (cpumask_subset(pool
->attrs
->cpumask
,
3270 wq_numa_possible_cpumask
[node
])) {
3277 if (worker_pool_assign_id(pool
) < 0)
3280 /* create and start the initial worker */
3281 if (!create_worker(pool
))
3285 hash_add(unbound_pool_hash
, &pool
->hash_node
, hash
);
3290 put_unbound_pool(pool
);
3294 static void rcu_free_pwq(struct rcu_head
*rcu
)
3296 kmem_cache_free(pwq_cache
,
3297 container_of(rcu
, struct pool_workqueue
, rcu
));
3301 * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt
3302 * and needs to be destroyed.
3304 static void pwq_unbound_release_workfn(struct work_struct
*work
)
3306 struct pool_workqueue
*pwq
= container_of(work
, struct pool_workqueue
,
3307 unbound_release_work
);
3308 struct workqueue_struct
*wq
= pwq
->wq
;
3309 struct worker_pool
*pool
= pwq
->pool
;
3312 if (WARN_ON_ONCE(!(wq
->flags
& WQ_UNBOUND
)))
3315 mutex_lock(&wq
->mutex
);
3316 list_del_rcu(&pwq
->pwqs_node
);
3317 is_last
= list_empty(&wq
->pwqs
);
3318 mutex_unlock(&wq
->mutex
);
3320 mutex_lock(&wq_pool_mutex
);
3321 put_unbound_pool(pool
);
3322 mutex_unlock(&wq_pool_mutex
);
3324 call_rcu_sched(&pwq
->rcu
, rcu_free_pwq
);
3327 * If we're the last pwq going away, @wq is already dead and no one
3328 * is gonna access it anymore. Schedule RCU free.
3331 call_rcu_sched(&wq
->rcu
, rcu_free_wq
);
3335 * pwq_adjust_max_active - update a pwq's max_active to the current setting
3336 * @pwq: target pool_workqueue
3338 * If @pwq isn't freezing, set @pwq->max_active to the associated
3339 * workqueue's saved_max_active and activate delayed work items
3340 * accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
3342 static void pwq_adjust_max_active(struct pool_workqueue
*pwq
)
3344 struct workqueue_struct
*wq
= pwq
->wq
;
3345 bool freezable
= wq
->flags
& WQ_FREEZABLE
;
3347 /* for @wq->saved_max_active */
3348 lockdep_assert_held(&wq
->mutex
);
3350 /* fast exit for non-freezable wqs */
3351 if (!freezable
&& pwq
->max_active
== wq
->saved_max_active
)
3354 spin_lock_irq(&pwq
->pool
->lock
);
3357 * During [un]freezing, the caller is responsible for ensuring that
3358 * this function is called at least once after @workqueue_freezing
3359 * is updated and visible.
3361 if (!freezable
|| !workqueue_freezing
) {
3362 pwq
->max_active
= wq
->saved_max_active
;
3364 while (!list_empty(&pwq
->delayed_works
) &&
3365 pwq
->nr_active
< pwq
->max_active
)
3366 pwq_activate_first_delayed(pwq
);
3369 * Need to kick a worker after thawed or an unbound wq's
3370 * max_active is bumped. It's a slow path. Do it always.
3372 wake_up_worker(pwq
->pool
);
3374 pwq
->max_active
= 0;
3377 spin_unlock_irq(&pwq
->pool
->lock
);
3380 /* initialize newly alloced @pwq which is associated with @wq and @pool */
3381 static void init_pwq(struct pool_workqueue
*pwq
, struct workqueue_struct
*wq
,
3382 struct worker_pool
*pool
)
3384 BUG_ON((unsigned long)pwq
& WORK_STRUCT_FLAG_MASK
);
3386 memset(pwq
, 0, sizeof(*pwq
));
3390 pwq
->flush_color
= -1;
3392 INIT_LIST_HEAD(&pwq
->delayed_works
);
3393 INIT_LIST_HEAD(&pwq
->pwqs_node
);
3394 INIT_LIST_HEAD(&pwq
->mayday_node
);
3395 INIT_WORK(&pwq
->unbound_release_work
, pwq_unbound_release_workfn
);
3398 /* sync @pwq with the current state of its associated wq and link it */
3399 static void link_pwq(struct pool_workqueue
*pwq
)
3401 struct workqueue_struct
*wq
= pwq
->wq
;
3403 lockdep_assert_held(&wq
->mutex
);
3405 /* may be called multiple times, ignore if already linked */
3406 if (!list_empty(&pwq
->pwqs_node
))
3409 /* set the matching work_color */
3410 pwq
->work_color
= wq
->work_color
;
3412 /* sync max_active to the current setting */
3413 pwq_adjust_max_active(pwq
);
3416 list_add_rcu(&pwq
->pwqs_node
, &wq
->pwqs
);
3419 /* obtain a pool matching @attr and create a pwq associating the pool and @wq */
3420 static struct pool_workqueue
*alloc_unbound_pwq(struct workqueue_struct
*wq
,
3421 const struct workqueue_attrs
*attrs
)
3423 struct worker_pool
*pool
;
3424 struct pool_workqueue
*pwq
;
3426 lockdep_assert_held(&wq_pool_mutex
);
3428 pool
= get_unbound_pool(attrs
);
3432 pwq
= kmem_cache_alloc_node(pwq_cache
, GFP_KERNEL
, pool
->node
);
3434 put_unbound_pool(pool
);
3438 init_pwq(pwq
, wq
, pool
);
3443 * wq_calc_node_cpumask - calculate a wq_attrs' cpumask for the specified node
3444 * @attrs: the wq_attrs of the default pwq of the target workqueue
3445 * @node: the target NUMA node
3446 * @cpu_going_down: if >= 0, the CPU to consider as offline
3447 * @cpumask: outarg, the resulting cpumask
3449 * Calculate the cpumask a workqueue with @attrs should use on @node. If
3450 * @cpu_going_down is >= 0, that cpu is considered offline during
3451 * calculation. The result is stored in @cpumask.
3453 * If NUMA affinity is not enabled, @attrs->cpumask is always used. If
3454 * enabled and @node has online CPUs requested by @attrs, the returned
3455 * cpumask is the intersection of the possible CPUs of @node and
3458 * The caller is responsible for ensuring that the cpumask of @node stays
3461 * Return: %true if the resulting @cpumask is different from @attrs->cpumask,
3464 static bool wq_calc_node_cpumask(const struct workqueue_attrs
*attrs
, int node
,
3465 int cpu_going_down
, cpumask_t
*cpumask
)
3467 if (!wq_numa_enabled
|| attrs
->no_numa
)
3470 /* does @node have any online CPUs @attrs wants? */
3471 cpumask_and(cpumask
, cpumask_of_node(node
), attrs
->cpumask
);
3472 if (cpu_going_down
>= 0)
3473 cpumask_clear_cpu(cpu_going_down
, cpumask
);
3475 if (cpumask_empty(cpumask
))
3478 /* yeap, return possible CPUs in @node that @attrs wants */
3479 cpumask_and(cpumask
, attrs
->cpumask
, wq_numa_possible_cpumask
[node
]);
3480 return !cpumask_equal(cpumask
, attrs
->cpumask
);
3483 cpumask_copy(cpumask
, attrs
->cpumask
);
3487 /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
3488 static struct pool_workqueue
*numa_pwq_tbl_install(struct workqueue_struct
*wq
,
3490 struct pool_workqueue
*pwq
)
3492 struct pool_workqueue
*old_pwq
;
3494 lockdep_assert_held(&wq_pool_mutex
);
3495 lockdep_assert_held(&wq
->mutex
);
3497 /* link_pwq() can handle duplicate calls */
3500 old_pwq
= rcu_access_pointer(wq
->numa_pwq_tbl
[node
]);
3501 rcu_assign_pointer(wq
->numa_pwq_tbl
[node
], pwq
);
3505 /* context to store the prepared attrs & pwqs before applying */
3506 struct apply_wqattrs_ctx
{
3507 struct workqueue_struct
*wq
; /* target workqueue */
3508 struct workqueue_attrs
*attrs
; /* attrs to apply */
3509 struct list_head list
; /* queued for batching commit */
3510 struct pool_workqueue
*dfl_pwq
;
3511 struct pool_workqueue
*pwq_tbl
[];
3514 /* free the resources after success or abort */
3515 static void apply_wqattrs_cleanup(struct apply_wqattrs_ctx
*ctx
)
3521 put_pwq_unlocked(ctx
->pwq_tbl
[node
]);
3522 put_pwq_unlocked(ctx
->dfl_pwq
);
3524 free_workqueue_attrs(ctx
->attrs
);
3530 /* allocate the attrs and pwqs for later installation */
3531 static struct apply_wqattrs_ctx
*
3532 apply_wqattrs_prepare(struct workqueue_struct
*wq
,
3533 const struct workqueue_attrs
*attrs
)
3535 struct apply_wqattrs_ctx
*ctx
;
3536 struct workqueue_attrs
*new_attrs
, *tmp_attrs
;
3539 lockdep_assert_held(&wq_pool_mutex
);
3541 ctx
= kzalloc(sizeof(*ctx
) + nr_node_ids
* sizeof(ctx
->pwq_tbl
[0]),
3544 new_attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3545 tmp_attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3546 if (!ctx
|| !new_attrs
|| !tmp_attrs
)
3550 * Calculate the attrs of the default pwq.
3551 * If the user configured cpumask doesn't overlap with the
3552 * wq_unbound_cpumask, we fallback to the wq_unbound_cpumask.
3554 copy_workqueue_attrs(new_attrs
, attrs
);
3555 cpumask_and(new_attrs
->cpumask
, new_attrs
->cpumask
, wq_unbound_cpumask
);
3556 if (unlikely(cpumask_empty(new_attrs
->cpumask
)))
3557 cpumask_copy(new_attrs
->cpumask
, wq_unbound_cpumask
);
3560 * We may create multiple pwqs with differing cpumasks. Make a
3561 * copy of @new_attrs which will be modified and used to obtain
3564 copy_workqueue_attrs(tmp_attrs
, new_attrs
);
3567 * If something goes wrong during CPU up/down, we'll fall back to
3568 * the default pwq covering whole @attrs->cpumask. Always create
3569 * it even if we don't use it immediately.
3571 ctx
->dfl_pwq
= alloc_unbound_pwq(wq
, new_attrs
);
3575 for_each_node(node
) {
3576 if (wq_calc_node_cpumask(new_attrs
, node
, -1, tmp_attrs
->cpumask
)) {
3577 ctx
->pwq_tbl
[node
] = alloc_unbound_pwq(wq
, tmp_attrs
);
3578 if (!ctx
->pwq_tbl
[node
])
3581 ctx
->dfl_pwq
->refcnt
++;
3582 ctx
->pwq_tbl
[node
] = ctx
->dfl_pwq
;
3586 /* save the user configured attrs and sanitize it. */
3587 copy_workqueue_attrs(new_attrs
, attrs
);
3588 cpumask_and(new_attrs
->cpumask
, new_attrs
->cpumask
, cpu_possible_mask
);
3589 ctx
->attrs
= new_attrs
;
3592 free_workqueue_attrs(tmp_attrs
);
3596 free_workqueue_attrs(tmp_attrs
);
3597 free_workqueue_attrs(new_attrs
);
3598 apply_wqattrs_cleanup(ctx
);
3602 /* set attrs and install prepared pwqs, @ctx points to old pwqs on return */
3603 static void apply_wqattrs_commit(struct apply_wqattrs_ctx
*ctx
)
3607 /* all pwqs have been created successfully, let's install'em */
3608 mutex_lock(&ctx
->wq
->mutex
);
3610 copy_workqueue_attrs(ctx
->wq
->unbound_attrs
, ctx
->attrs
);
3612 /* save the previous pwq and install the new one */
3614 ctx
->pwq_tbl
[node
] = numa_pwq_tbl_install(ctx
->wq
, node
,
3615 ctx
->pwq_tbl
[node
]);
3617 /* @dfl_pwq might not have been used, ensure it's linked */
3618 link_pwq(ctx
->dfl_pwq
);
3619 swap(ctx
->wq
->dfl_pwq
, ctx
->dfl_pwq
);
3621 mutex_unlock(&ctx
->wq
->mutex
);
3624 static void apply_wqattrs_lock(void)
3626 /* CPUs should stay stable across pwq creations and installations */
3628 mutex_lock(&wq_pool_mutex
);
3631 static void apply_wqattrs_unlock(void)
3633 mutex_unlock(&wq_pool_mutex
);
3637 static int apply_workqueue_attrs_locked(struct workqueue_struct
*wq
,
3638 const struct workqueue_attrs
*attrs
)
3640 struct apply_wqattrs_ctx
*ctx
;
3643 /* only unbound workqueues can change attributes */
3644 if (WARN_ON(!(wq
->flags
& WQ_UNBOUND
)))
3647 /* creating multiple pwqs breaks ordering guarantee */
3648 if (WARN_ON((wq
->flags
& __WQ_ORDERED
) && !list_empty(&wq
->pwqs
)))
3651 ctx
= apply_wqattrs_prepare(wq
, attrs
);
3653 /* the ctx has been prepared successfully, let's commit it */
3655 apply_wqattrs_commit(ctx
);
3659 apply_wqattrs_cleanup(ctx
);
3665 * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
3666 * @wq: the target workqueue
3667 * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
3669 * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
3670 * machines, this function maps a separate pwq to each NUMA node with
3671 * possibles CPUs in @attrs->cpumask so that work items are affine to the
3672 * NUMA node it was issued on. Older pwqs are released as in-flight work
3673 * items finish. Note that a work item which repeatedly requeues itself
3674 * back-to-back will stay on its current pwq.
3676 * Performs GFP_KERNEL allocations.
3678 * Return: 0 on success and -errno on failure.
3680 int apply_workqueue_attrs(struct workqueue_struct
*wq
,
3681 const struct workqueue_attrs
*attrs
)
3685 apply_wqattrs_lock();
3686 ret
= apply_workqueue_attrs_locked(wq
, attrs
);
3687 apply_wqattrs_unlock();
3693 * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
3694 * @wq: the target workqueue
3695 * @cpu: the CPU coming up or going down
3696 * @online: whether @cpu is coming up or going down
3698 * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
3699 * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
3702 * If NUMA affinity can't be adjusted due to memory allocation failure, it
3703 * falls back to @wq->dfl_pwq which may not be optimal but is always
3706 * Note that when the last allowed CPU of a NUMA node goes offline for a
3707 * workqueue with a cpumask spanning multiple nodes, the workers which were
3708 * already executing the work items for the workqueue will lose their CPU
3709 * affinity and may execute on any CPU. This is similar to how per-cpu
3710 * workqueues behave on CPU_DOWN. If a workqueue user wants strict
3711 * affinity, it's the user's responsibility to flush the work item from
3714 static void wq_update_unbound_numa(struct workqueue_struct
*wq
, int cpu
,
3717 int node
= cpu_to_node(cpu
);
3718 int cpu_off
= online
? -1 : cpu
;
3719 struct pool_workqueue
*old_pwq
= NULL
, *pwq
;
3720 struct workqueue_attrs
*target_attrs
;
3723 lockdep_assert_held(&wq_pool_mutex
);
3725 if (!wq_numa_enabled
|| !(wq
->flags
& WQ_UNBOUND
) ||
3726 wq
->unbound_attrs
->no_numa
)
3730 * We don't wanna alloc/free wq_attrs for each wq for each CPU.
3731 * Let's use a preallocated one. The following buf is protected by
3732 * CPU hotplug exclusion.
3734 target_attrs
= wq_update_unbound_numa_attrs_buf
;
3735 cpumask
= target_attrs
->cpumask
;
3737 copy_workqueue_attrs(target_attrs
, wq
->unbound_attrs
);
3738 pwq
= unbound_pwq_by_node(wq
, node
);
3741 * Let's determine what needs to be done. If the target cpumask is
3742 * different from the default pwq's, we need to compare it to @pwq's
3743 * and create a new one if they don't match. If the target cpumask
3744 * equals the default pwq's, the default pwq should be used.
3746 if (wq_calc_node_cpumask(wq
->dfl_pwq
->pool
->attrs
, node
, cpu_off
, cpumask
)) {
3747 if (cpumask_equal(cpumask
, pwq
->pool
->attrs
->cpumask
))
3753 /* create a new pwq */
3754 pwq
= alloc_unbound_pwq(wq
, target_attrs
);
3756 pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
3761 /* Install the new pwq. */
3762 mutex_lock(&wq
->mutex
);
3763 old_pwq
= numa_pwq_tbl_install(wq
, node
, pwq
);
3767 mutex_lock(&wq
->mutex
);
3768 spin_lock_irq(&wq
->dfl_pwq
->pool
->lock
);
3769 get_pwq(wq
->dfl_pwq
);
3770 spin_unlock_irq(&wq
->dfl_pwq
->pool
->lock
);
3771 old_pwq
= numa_pwq_tbl_install(wq
, node
, wq
->dfl_pwq
);
3773 mutex_unlock(&wq
->mutex
);
3774 put_pwq_unlocked(old_pwq
);
3777 static int alloc_and_link_pwqs(struct workqueue_struct
*wq
)
3779 bool highpri
= wq
->flags
& WQ_HIGHPRI
;
3782 if (!(wq
->flags
& WQ_UNBOUND
)) {
3783 wq
->cpu_pwqs
= alloc_percpu(struct pool_workqueue
);
3787 for_each_possible_cpu(cpu
) {
3788 struct pool_workqueue
*pwq
=
3789 per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
3790 struct worker_pool
*cpu_pools
=
3791 per_cpu(cpu_worker_pools
, cpu
);
3793 init_pwq(pwq
, wq
, &cpu_pools
[highpri
]);
3795 mutex_lock(&wq
->mutex
);
3797 mutex_unlock(&wq
->mutex
);
3800 } else if (wq
->flags
& __WQ_ORDERED
) {
3801 ret
= apply_workqueue_attrs(wq
, ordered_wq_attrs
[highpri
]);
3802 /* there should only be single pwq for ordering guarantee */
3803 WARN(!ret
&& (wq
->pwqs
.next
!= &wq
->dfl_pwq
->pwqs_node
||
3804 wq
->pwqs
.prev
!= &wq
->dfl_pwq
->pwqs_node
),
3805 "ordering guarantee broken for workqueue %s\n", wq
->name
);
3808 return apply_workqueue_attrs(wq
, unbound_std_wq_attrs
[highpri
]);
3812 static int wq_clamp_max_active(int max_active
, unsigned int flags
,
3815 int lim
= flags
& WQ_UNBOUND
? WQ_UNBOUND_MAX_ACTIVE
: WQ_MAX_ACTIVE
;
3817 if (max_active
< 1 || max_active
> lim
)
3818 pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
3819 max_active
, name
, 1, lim
);
3821 return clamp_val(max_active
, 1, lim
);
3824 struct workqueue_struct
*__alloc_workqueue_key(const char *fmt
,
3827 struct lock_class_key
*key
,
3828 const char *lock_name
, ...)
3830 size_t tbl_size
= 0;
3832 struct workqueue_struct
*wq
;
3833 struct pool_workqueue
*pwq
;
3835 /* see the comment above the definition of WQ_POWER_EFFICIENT */
3836 if ((flags
& WQ_POWER_EFFICIENT
) && wq_power_efficient
)
3837 flags
|= WQ_UNBOUND
;
3839 /* allocate wq and format name */
3840 if (flags
& WQ_UNBOUND
)
3841 tbl_size
= nr_node_ids
* sizeof(wq
->numa_pwq_tbl
[0]);
3843 wq
= kzalloc(sizeof(*wq
) + tbl_size
, GFP_KERNEL
);
3847 if (flags
& WQ_UNBOUND
) {
3848 wq
->unbound_attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3849 if (!wq
->unbound_attrs
)
3853 va_start(args
, lock_name
);
3854 vsnprintf(wq
->name
, sizeof(wq
->name
), fmt
, args
);
3857 max_active
= max_active
?: WQ_DFL_ACTIVE
;
3858 max_active
= wq_clamp_max_active(max_active
, flags
, wq
->name
);
3862 wq
->saved_max_active
= max_active
;
3863 mutex_init(&wq
->mutex
);
3864 atomic_set(&wq
->nr_pwqs_to_flush
, 0);
3865 INIT_LIST_HEAD(&wq
->pwqs
);
3866 INIT_LIST_HEAD(&wq
->flusher_queue
);
3867 INIT_LIST_HEAD(&wq
->flusher_overflow
);
3868 INIT_LIST_HEAD(&wq
->maydays
);
3870 lockdep_init_map(&wq
->lockdep_map
, lock_name
, key
, 0);
3871 INIT_LIST_HEAD(&wq
->list
);
3873 if (alloc_and_link_pwqs(wq
) < 0)
3877 * Workqueues which may be used during memory reclaim should
3878 * have a rescuer to guarantee forward progress.
3880 if (flags
& WQ_MEM_RECLAIM
) {
3881 struct worker
*rescuer
;
3883 rescuer
= alloc_worker(NUMA_NO_NODE
);
3887 rescuer
->rescue_wq
= wq
;
3888 rescuer
->task
= kthread_create(rescuer_thread
, rescuer
, "%s",
3890 if (IS_ERR(rescuer
->task
)) {
3895 wq
->rescuer
= rescuer
;
3896 rescuer
->task
->flags
|= PF_NO_SETAFFINITY
;
3897 wake_up_process(rescuer
->task
);
3900 if ((wq
->flags
& WQ_SYSFS
) && workqueue_sysfs_register(wq
))
3904 * wq_pool_mutex protects global freeze state and workqueues list.
3905 * Grab it, adjust max_active and add the new @wq to workqueues
3908 mutex_lock(&wq_pool_mutex
);
3910 mutex_lock(&wq
->mutex
);
3911 for_each_pwq(pwq
, wq
)
3912 pwq_adjust_max_active(pwq
);
3913 mutex_unlock(&wq
->mutex
);
3915 list_add_tail_rcu(&wq
->list
, &workqueues
);
3917 mutex_unlock(&wq_pool_mutex
);
3922 free_workqueue_attrs(wq
->unbound_attrs
);
3926 destroy_workqueue(wq
);
3929 EXPORT_SYMBOL_GPL(__alloc_workqueue_key
);
3932 * destroy_workqueue - safely terminate a workqueue
3933 * @wq: target workqueue
3935 * Safely destroy a workqueue. All work currently pending will be done first.
3937 void destroy_workqueue(struct workqueue_struct
*wq
)
3939 struct pool_workqueue
*pwq
;
3942 /* drain it before proceeding with destruction */
3943 drain_workqueue(wq
);
3946 mutex_lock(&wq
->mutex
);
3947 for_each_pwq(pwq
, wq
) {
3950 for (i
= 0; i
< WORK_NR_COLORS
; i
++) {
3951 if (WARN_ON(pwq
->nr_in_flight
[i
])) {
3952 mutex_unlock(&wq
->mutex
);
3957 if (WARN_ON((pwq
!= wq
->dfl_pwq
) && (pwq
->refcnt
> 1)) ||
3958 WARN_ON(pwq
->nr_active
) ||
3959 WARN_ON(!list_empty(&pwq
->delayed_works
))) {
3960 mutex_unlock(&wq
->mutex
);
3964 mutex_unlock(&wq
->mutex
);
3967 * wq list is used to freeze wq, remove from list after
3968 * flushing is complete in case freeze races us.
3970 mutex_lock(&wq_pool_mutex
);
3971 list_del_rcu(&wq
->list
);
3972 mutex_unlock(&wq_pool_mutex
);
3974 workqueue_sysfs_unregister(wq
);
3977 kthread_stop(wq
->rescuer
->task
);
3979 if (!(wq
->flags
& WQ_UNBOUND
)) {
3981 * The base ref is never dropped on per-cpu pwqs. Directly
3982 * schedule RCU free.
3984 call_rcu_sched(&wq
->rcu
, rcu_free_wq
);
3987 * We're the sole accessor of @wq at this point. Directly
3988 * access numa_pwq_tbl[] and dfl_pwq to put the base refs.
3989 * @wq will be freed when the last pwq is released.
3991 for_each_node(node
) {
3992 pwq
= rcu_access_pointer(wq
->numa_pwq_tbl
[node
]);
3993 RCU_INIT_POINTER(wq
->numa_pwq_tbl
[node
], NULL
);
3994 put_pwq_unlocked(pwq
);
3998 * Put dfl_pwq. @wq may be freed any time after dfl_pwq is
3999 * put. Don't access it afterwards.
4003 put_pwq_unlocked(pwq
);
4006 EXPORT_SYMBOL_GPL(destroy_workqueue
);
4009 * workqueue_set_max_active - adjust max_active of a workqueue
4010 * @wq: target workqueue
4011 * @max_active: new max_active value.
4013 * Set max_active of @wq to @max_active.
4016 * Don't call from IRQ context.
4018 void workqueue_set_max_active(struct workqueue_struct
*wq
, int max_active
)
4020 struct pool_workqueue
*pwq
;
4022 /* disallow meddling with max_active for ordered workqueues */
4023 if (WARN_ON(wq
->flags
& __WQ_ORDERED
))
4026 max_active
= wq_clamp_max_active(max_active
, wq
->flags
, wq
->name
);
4028 mutex_lock(&wq
->mutex
);
4030 wq
->saved_max_active
= max_active
;
4032 for_each_pwq(pwq
, wq
)
4033 pwq_adjust_max_active(pwq
);
4035 mutex_unlock(&wq
->mutex
);
4037 EXPORT_SYMBOL_GPL(workqueue_set_max_active
);
4040 * current_is_workqueue_rescuer - is %current workqueue rescuer?
4042 * Determine whether %current is a workqueue rescuer. Can be used from
4043 * work functions to determine whether it's being run off the rescuer task.
4045 * Return: %true if %current is a workqueue rescuer. %false otherwise.
4047 bool current_is_workqueue_rescuer(void)
4049 struct worker
*worker
= current_wq_worker();
4051 return worker
&& worker
->rescue_wq
;
4055 * workqueue_congested - test whether a workqueue is congested
4056 * @cpu: CPU in question
4057 * @wq: target workqueue
4059 * Test whether @wq's cpu workqueue for @cpu is congested. There is
4060 * no synchronization around this function and the test result is
4061 * unreliable and only useful as advisory hints or for debugging.
4063 * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU.
4064 * Note that both per-cpu and unbound workqueues may be associated with
4065 * multiple pool_workqueues which have separate congested states. A
4066 * workqueue being congested on one CPU doesn't mean the workqueue is also
4067 * contested on other CPUs / NUMA nodes.
4070 * %true if congested, %false otherwise.
4072 bool workqueue_congested(int cpu
, struct workqueue_struct
*wq
)
4074 struct pool_workqueue
*pwq
;
4077 rcu_read_lock_sched();
4079 if (cpu
== WORK_CPU_UNBOUND
)
4080 cpu
= smp_processor_id();
4082 if (!(wq
->flags
& WQ_UNBOUND
))
4083 pwq
= per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
4085 pwq
= unbound_pwq_by_node(wq
, cpu_to_node(cpu
));
4087 ret
= !list_empty(&pwq
->delayed_works
);
4088 rcu_read_unlock_sched();
4092 EXPORT_SYMBOL_GPL(workqueue_congested
);
4095 * work_busy - test whether a work is currently pending or running
4096 * @work: the work to be tested
4098 * Test whether @work is currently pending or running. There is no
4099 * synchronization around this function and the test result is
4100 * unreliable and only useful as advisory hints or for debugging.
4103 * OR'd bitmask of WORK_BUSY_* bits.
4105 unsigned int work_busy(struct work_struct
*work
)
4107 struct worker_pool
*pool
;
4108 unsigned long flags
;
4109 unsigned int ret
= 0;
4111 if (work_pending(work
))
4112 ret
|= WORK_BUSY_PENDING
;
4114 local_irq_save(flags
);
4115 pool
= get_work_pool(work
);
4117 spin_lock(&pool
->lock
);
4118 if (find_worker_executing_work(pool
, work
))
4119 ret
|= WORK_BUSY_RUNNING
;
4120 spin_unlock(&pool
->lock
);
4122 local_irq_restore(flags
);
4126 EXPORT_SYMBOL_GPL(work_busy
);
4129 * set_worker_desc - set description for the current work item
4130 * @fmt: printf-style format string
4131 * @...: arguments for the format string
4133 * This function can be called by a running work function to describe what
4134 * the work item is about. If the worker task gets dumped, this
4135 * information will be printed out together to help debugging. The
4136 * description can be at most WORKER_DESC_LEN including the trailing '\0'.
4138 void set_worker_desc(const char *fmt
, ...)
4140 struct worker
*worker
= current_wq_worker();
4144 va_start(args
, fmt
);
4145 vsnprintf(worker
->desc
, sizeof(worker
->desc
), fmt
, args
);
4147 worker
->desc_valid
= true;
4152 * print_worker_info - print out worker information and description
4153 * @log_lvl: the log level to use when printing
4154 * @task: target task
4156 * If @task is a worker and currently executing a work item, print out the
4157 * name of the workqueue being serviced and worker description set with
4158 * set_worker_desc() by the currently executing work item.
4160 * This function can be safely called on any task as long as the
4161 * task_struct itself is accessible. While safe, this function isn't
4162 * synchronized and may print out mixups or garbages of limited length.
4164 void print_worker_info(const char *log_lvl
, struct task_struct
*task
)
4166 work_func_t
*fn
= NULL
;
4167 char name
[WQ_NAME_LEN
] = { };
4168 char desc
[WORKER_DESC_LEN
] = { };
4169 struct pool_workqueue
*pwq
= NULL
;
4170 struct workqueue_struct
*wq
= NULL
;
4171 bool desc_valid
= false;
4172 struct worker
*worker
;
4174 if (!(task
->flags
& PF_WQ_WORKER
))
4178 * This function is called without any synchronization and @task
4179 * could be in any state. Be careful with dereferences.
4181 worker
= probe_kthread_data(task
);
4184 * Carefully copy the associated workqueue's workfn and name. Keep
4185 * the original last '\0' in case the original contains garbage.
4187 probe_kernel_read(&fn
, &worker
->current_func
, sizeof(fn
));
4188 probe_kernel_read(&pwq
, &worker
->current_pwq
, sizeof(pwq
));
4189 probe_kernel_read(&wq
, &pwq
->wq
, sizeof(wq
));
4190 probe_kernel_read(name
, wq
->name
, sizeof(name
) - 1);
4192 /* copy worker description */
4193 probe_kernel_read(&desc_valid
, &worker
->desc_valid
, sizeof(desc_valid
));
4195 probe_kernel_read(desc
, worker
->desc
, sizeof(desc
) - 1);
4197 if (fn
|| name
[0] || desc
[0]) {
4198 printk("%sWorkqueue: %s %pf", log_lvl
, name
, fn
);
4200 pr_cont(" (%s)", desc
);
4205 static void pr_cont_pool_info(struct worker_pool
*pool
)
4207 pr_cont(" cpus=%*pbl", nr_cpumask_bits
, pool
->attrs
->cpumask
);
4208 if (pool
->node
!= NUMA_NO_NODE
)
4209 pr_cont(" node=%d", pool
->node
);
4210 pr_cont(" flags=0x%x nice=%d", pool
->flags
, pool
->attrs
->nice
);
4213 static void pr_cont_work(bool comma
, struct work_struct
*work
)
4215 if (work
->func
== wq_barrier_func
) {
4216 struct wq_barrier
*barr
;
4218 barr
= container_of(work
, struct wq_barrier
, work
);
4220 pr_cont("%s BAR(%d)", comma
? "," : "",
4221 task_pid_nr(barr
->task
));
4223 pr_cont("%s %pf", comma
? "," : "", work
->func
);
4227 static void show_pwq(struct pool_workqueue
*pwq
)
4229 struct worker_pool
*pool
= pwq
->pool
;
4230 struct work_struct
*work
;
4231 struct worker
*worker
;
4232 bool has_in_flight
= false, has_pending
= false;
4235 pr_info(" pwq %d:", pool
->id
);
4236 pr_cont_pool_info(pool
);
4238 pr_cont(" active=%d/%d%s\n", pwq
->nr_active
, pwq
->max_active
,
4239 !list_empty(&pwq
->mayday_node
) ? " MAYDAY" : "");
4241 hash_for_each(pool
->busy_hash
, bkt
, worker
, hentry
) {
4242 if (worker
->current_pwq
== pwq
) {
4243 has_in_flight
= true;
4247 if (has_in_flight
) {
4250 pr_info(" in-flight:");
4251 hash_for_each(pool
->busy_hash
, bkt
, worker
, hentry
) {
4252 if (worker
->current_pwq
!= pwq
)
4255 pr_cont("%s %d%s:%pf", comma
? "," : "",
4256 task_pid_nr(worker
->task
),
4257 worker
== pwq
->wq
->rescuer
? "(RESCUER)" : "",
4258 worker
->current_func
);
4259 list_for_each_entry(work
, &worker
->scheduled
, entry
)
4260 pr_cont_work(false, work
);
4266 list_for_each_entry(work
, &pool
->worklist
, entry
) {
4267 if (get_work_pwq(work
) == pwq
) {
4275 pr_info(" pending:");
4276 list_for_each_entry(work
, &pool
->worklist
, entry
) {
4277 if (get_work_pwq(work
) != pwq
)
4280 pr_cont_work(comma
, work
);
4281 comma
= !(*work_data_bits(work
) & WORK_STRUCT_LINKED
);
4286 if (!list_empty(&pwq
->delayed_works
)) {
4289 pr_info(" delayed:");
4290 list_for_each_entry(work
, &pwq
->delayed_works
, entry
) {
4291 pr_cont_work(comma
, work
);
4292 comma
= !(*work_data_bits(work
) & WORK_STRUCT_LINKED
);
4299 * show_workqueue_state - dump workqueue state
4301 * Called from a sysrq handler and prints out all busy workqueues and
4304 void show_workqueue_state(void)
4306 struct workqueue_struct
*wq
;
4307 struct worker_pool
*pool
;
4308 unsigned long flags
;
4311 rcu_read_lock_sched();
4313 pr_info("Showing busy workqueues and worker pools:\n");
4315 list_for_each_entry_rcu(wq
, &workqueues
, list
) {
4316 struct pool_workqueue
*pwq
;
4319 for_each_pwq(pwq
, wq
) {
4320 if (pwq
->nr_active
|| !list_empty(&pwq
->delayed_works
)) {
4328 pr_info("workqueue %s: flags=0x%x\n", wq
->name
, wq
->flags
);
4330 for_each_pwq(pwq
, wq
) {
4331 spin_lock_irqsave(&pwq
->pool
->lock
, flags
);
4332 if (pwq
->nr_active
|| !list_empty(&pwq
->delayed_works
))
4334 spin_unlock_irqrestore(&pwq
->pool
->lock
, flags
);
4338 for_each_pool(pool
, pi
) {
4339 struct worker
*worker
;
4342 spin_lock_irqsave(&pool
->lock
, flags
);
4343 if (pool
->nr_workers
== pool
->nr_idle
)
4346 pr_info("pool %d:", pool
->id
);
4347 pr_cont_pool_info(pool
);
4348 pr_cont(" workers=%d", pool
->nr_workers
);
4350 pr_cont(" manager: %d",
4351 task_pid_nr(pool
->manager
->task
));
4352 list_for_each_entry(worker
, &pool
->idle_list
, entry
) {
4353 pr_cont(" %s%d", first
? "idle: " : "",
4354 task_pid_nr(worker
->task
));
4359 spin_unlock_irqrestore(&pool
->lock
, flags
);
4362 rcu_read_unlock_sched();
4368 * There are two challenges in supporting CPU hotplug. Firstly, there
4369 * are a lot of assumptions on strong associations among work, pwq and
4370 * pool which make migrating pending and scheduled works very
4371 * difficult to implement without impacting hot paths. Secondly,
4372 * worker pools serve mix of short, long and very long running works making
4373 * blocked draining impractical.
4375 * This is solved by allowing the pools to be disassociated from the CPU
4376 * running as an unbound one and allowing it to be reattached later if the
4377 * cpu comes back online.
4380 static void wq_unbind_fn(struct work_struct
*work
)
4382 int cpu
= smp_processor_id();
4383 struct worker_pool
*pool
;
4384 struct worker
*worker
;
4386 for_each_cpu_worker_pool(pool
, cpu
) {
4387 mutex_lock(&pool
->attach_mutex
);
4388 spin_lock_irq(&pool
->lock
);
4391 * We've blocked all attach/detach operations. Make all workers
4392 * unbound and set DISASSOCIATED. Before this, all workers
4393 * except for the ones which are still executing works from
4394 * before the last CPU down must be on the cpu. After
4395 * this, they may become diasporas.
4397 for_each_pool_worker(worker
, pool
)
4398 worker
->flags
|= WORKER_UNBOUND
;
4400 pool
->flags
|= POOL_DISASSOCIATED
;
4402 spin_unlock_irq(&pool
->lock
);
4403 mutex_unlock(&pool
->attach_mutex
);
4406 * Call schedule() so that we cross rq->lock and thus can
4407 * guarantee sched callbacks see the %WORKER_UNBOUND flag.
4408 * This is necessary as scheduler callbacks may be invoked
4414 * Sched callbacks are disabled now. Zap nr_running.
4415 * After this, nr_running stays zero and need_more_worker()
4416 * and keep_working() are always true as long as the
4417 * worklist is not empty. This pool now behaves as an
4418 * unbound (in terms of concurrency management) pool which
4419 * are served by workers tied to the pool.
4421 atomic_set(&pool
->nr_running
, 0);
4424 * With concurrency management just turned off, a busy
4425 * worker blocking could lead to lengthy stalls. Kick off
4426 * unbound chain execution of currently pending work items.
4428 spin_lock_irq(&pool
->lock
);
4429 wake_up_worker(pool
);
4430 spin_unlock_irq(&pool
->lock
);
4435 * rebind_workers - rebind all workers of a pool to the associated CPU
4436 * @pool: pool of interest
4438 * @pool->cpu is coming online. Rebind all workers to the CPU.
4440 static void rebind_workers(struct worker_pool
*pool
)
4442 struct worker
*worker
;
4444 lockdep_assert_held(&pool
->attach_mutex
);
4447 * Restore CPU affinity of all workers. As all idle workers should
4448 * be on the run-queue of the associated CPU before any local
4449 * wake-ups for concurrency management happen, restore CPU affinty
4450 * of all workers first and then clear UNBOUND. As we're called
4451 * from CPU_ONLINE, the following shouldn't fail.
4453 for_each_pool_worker(worker
, pool
)
4454 WARN_ON_ONCE(set_cpus_allowed_ptr(worker
->task
,
4455 pool
->attrs
->cpumask
) < 0);
4457 spin_lock_irq(&pool
->lock
);
4458 pool
->flags
&= ~POOL_DISASSOCIATED
;
4460 for_each_pool_worker(worker
, pool
) {
4461 unsigned int worker_flags
= worker
->flags
;
4464 * A bound idle worker should actually be on the runqueue
4465 * of the associated CPU for local wake-ups targeting it to
4466 * work. Kick all idle workers so that they migrate to the
4467 * associated CPU. Doing this in the same loop as
4468 * replacing UNBOUND with REBOUND is safe as no worker will
4469 * be bound before @pool->lock is released.
4471 if (worker_flags
& WORKER_IDLE
)
4472 wake_up_process(worker
->task
);
4475 * We want to clear UNBOUND but can't directly call
4476 * worker_clr_flags() or adjust nr_running. Atomically
4477 * replace UNBOUND with another NOT_RUNNING flag REBOUND.
4478 * @worker will clear REBOUND using worker_clr_flags() when
4479 * it initiates the next execution cycle thus restoring
4480 * concurrency management. Note that when or whether
4481 * @worker clears REBOUND doesn't affect correctness.
4483 * ACCESS_ONCE() is necessary because @worker->flags may be
4484 * tested without holding any lock in
4485 * wq_worker_waking_up(). Without it, NOT_RUNNING test may
4486 * fail incorrectly leading to premature concurrency
4487 * management operations.
4489 WARN_ON_ONCE(!(worker_flags
& WORKER_UNBOUND
));
4490 worker_flags
|= WORKER_REBOUND
;
4491 worker_flags
&= ~WORKER_UNBOUND
;
4492 ACCESS_ONCE(worker
->flags
) = worker_flags
;
4495 spin_unlock_irq(&pool
->lock
);
4499 * restore_unbound_workers_cpumask - restore cpumask of unbound workers
4500 * @pool: unbound pool of interest
4501 * @cpu: the CPU which is coming up
4503 * An unbound pool may end up with a cpumask which doesn't have any online
4504 * CPUs. When a worker of such pool get scheduled, the scheduler resets
4505 * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
4506 * online CPU before, cpus_allowed of all its workers should be restored.
4508 static void restore_unbound_workers_cpumask(struct worker_pool
*pool
, int cpu
)
4510 static cpumask_t cpumask
;
4511 struct worker
*worker
;
4513 lockdep_assert_held(&pool
->attach_mutex
);
4515 /* is @cpu allowed for @pool? */
4516 if (!cpumask_test_cpu(cpu
, pool
->attrs
->cpumask
))
4519 /* is @cpu the only online CPU? */
4520 cpumask_and(&cpumask
, pool
->attrs
->cpumask
, cpu_online_mask
);
4521 if (cpumask_weight(&cpumask
) != 1)
4524 /* as we're called from CPU_ONLINE, the following shouldn't fail */
4525 for_each_pool_worker(worker
, pool
)
4526 WARN_ON_ONCE(set_cpus_allowed_ptr(worker
->task
,
4527 pool
->attrs
->cpumask
) < 0);
4531 * Workqueues should be brought up before normal priority CPU notifiers.
4532 * This will be registered high priority CPU notifier.
4534 static int workqueue_cpu_up_callback(struct notifier_block
*nfb
,
4535 unsigned long action
,
4538 int cpu
= (unsigned long)hcpu
;
4539 struct worker_pool
*pool
;
4540 struct workqueue_struct
*wq
;
4543 switch (action
& ~CPU_TASKS_FROZEN
) {
4544 case CPU_UP_PREPARE
:
4545 for_each_cpu_worker_pool(pool
, cpu
) {
4546 if (pool
->nr_workers
)
4548 if (!create_worker(pool
))
4553 case CPU_DOWN_FAILED
:
4555 mutex_lock(&wq_pool_mutex
);
4557 for_each_pool(pool
, pi
) {
4558 mutex_lock(&pool
->attach_mutex
);
4560 if (pool
->cpu
== cpu
)
4561 rebind_workers(pool
);
4562 else if (pool
->cpu
< 0)
4563 restore_unbound_workers_cpumask(pool
, cpu
);
4565 mutex_unlock(&pool
->attach_mutex
);
4568 /* update NUMA affinity of unbound workqueues */
4569 list_for_each_entry(wq
, &workqueues
, list
)
4570 wq_update_unbound_numa(wq
, cpu
, true);
4572 mutex_unlock(&wq_pool_mutex
);
4579 * Workqueues should be brought down after normal priority CPU notifiers.
4580 * This will be registered as low priority CPU notifier.
4582 static int workqueue_cpu_down_callback(struct notifier_block
*nfb
,
4583 unsigned long action
,
4586 int cpu
= (unsigned long)hcpu
;
4587 struct work_struct unbind_work
;
4588 struct workqueue_struct
*wq
;
4590 switch (action
& ~CPU_TASKS_FROZEN
) {
4591 case CPU_DOWN_PREPARE
:
4592 /* unbinding per-cpu workers should happen on the local CPU */
4593 INIT_WORK_ONSTACK(&unbind_work
, wq_unbind_fn
);
4594 queue_work_on(cpu
, system_highpri_wq
, &unbind_work
);
4596 /* update NUMA affinity of unbound workqueues */
4597 mutex_lock(&wq_pool_mutex
);
4598 list_for_each_entry(wq
, &workqueues
, list
)
4599 wq_update_unbound_numa(wq
, cpu
, false);
4600 mutex_unlock(&wq_pool_mutex
);
4602 /* wait for per-cpu unbinding to finish */
4603 flush_work(&unbind_work
);
4604 destroy_work_on_stack(&unbind_work
);
4612 struct work_for_cpu
{
4613 struct work_struct work
;
4619 static void work_for_cpu_fn(struct work_struct
*work
)
4621 struct work_for_cpu
*wfc
= container_of(work
, struct work_for_cpu
, work
);
4623 wfc
->ret
= wfc
->fn(wfc
->arg
);
4627 * work_on_cpu - run a function in user context on a particular cpu
4628 * @cpu: the cpu to run on
4629 * @fn: the function to run
4630 * @arg: the function arg
4632 * It is up to the caller to ensure that the cpu doesn't go offline.
4633 * The caller must not hold any locks which would prevent @fn from completing.
4635 * Return: The value @fn returns.
4637 long work_on_cpu(int cpu
, long (*fn
)(void *), void *arg
)
4639 struct work_for_cpu wfc
= { .fn
= fn
, .arg
= arg
};
4641 INIT_WORK_ONSTACK(&wfc
.work
, work_for_cpu_fn
);
4642 schedule_work_on(cpu
, &wfc
.work
);
4643 flush_work(&wfc
.work
);
4644 destroy_work_on_stack(&wfc
.work
);
4647 EXPORT_SYMBOL_GPL(work_on_cpu
);
4648 #endif /* CONFIG_SMP */
4650 #ifdef CONFIG_FREEZER
4653 * freeze_workqueues_begin - begin freezing workqueues
4655 * Start freezing workqueues. After this function returns, all freezable
4656 * workqueues will queue new works to their delayed_works list instead of
4660 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4662 void freeze_workqueues_begin(void)
4664 struct workqueue_struct
*wq
;
4665 struct pool_workqueue
*pwq
;
4667 mutex_lock(&wq_pool_mutex
);
4669 WARN_ON_ONCE(workqueue_freezing
);
4670 workqueue_freezing
= true;
4672 list_for_each_entry(wq
, &workqueues
, list
) {
4673 mutex_lock(&wq
->mutex
);
4674 for_each_pwq(pwq
, wq
)
4675 pwq_adjust_max_active(pwq
);
4676 mutex_unlock(&wq
->mutex
);
4679 mutex_unlock(&wq_pool_mutex
);
4683 * freeze_workqueues_busy - are freezable workqueues still busy?
4685 * Check whether freezing is complete. This function must be called
4686 * between freeze_workqueues_begin() and thaw_workqueues().
4689 * Grabs and releases wq_pool_mutex.
4692 * %true if some freezable workqueues are still busy. %false if freezing
4695 bool freeze_workqueues_busy(void)
4698 struct workqueue_struct
*wq
;
4699 struct pool_workqueue
*pwq
;
4701 mutex_lock(&wq_pool_mutex
);
4703 WARN_ON_ONCE(!workqueue_freezing
);
4705 list_for_each_entry(wq
, &workqueues
, list
) {
4706 if (!(wq
->flags
& WQ_FREEZABLE
))
4709 * nr_active is monotonically decreasing. It's safe
4710 * to peek without lock.
4712 rcu_read_lock_sched();
4713 for_each_pwq(pwq
, wq
) {
4714 WARN_ON_ONCE(pwq
->nr_active
< 0);
4715 if (pwq
->nr_active
) {
4717 rcu_read_unlock_sched();
4721 rcu_read_unlock_sched();
4724 mutex_unlock(&wq_pool_mutex
);
4729 * thaw_workqueues - thaw workqueues
4731 * Thaw workqueues. Normal queueing is restored and all collected
4732 * frozen works are transferred to their respective pool worklists.
4735 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4737 void thaw_workqueues(void)
4739 struct workqueue_struct
*wq
;
4740 struct pool_workqueue
*pwq
;
4742 mutex_lock(&wq_pool_mutex
);
4744 if (!workqueue_freezing
)
4747 workqueue_freezing
= false;
4749 /* restore max_active and repopulate worklist */
4750 list_for_each_entry(wq
, &workqueues
, list
) {
4751 mutex_lock(&wq
->mutex
);
4752 for_each_pwq(pwq
, wq
)
4753 pwq_adjust_max_active(pwq
);
4754 mutex_unlock(&wq
->mutex
);
4758 mutex_unlock(&wq_pool_mutex
);
4760 #endif /* CONFIG_FREEZER */
4762 static int workqueue_apply_unbound_cpumask(void)
4766 struct workqueue_struct
*wq
;
4767 struct apply_wqattrs_ctx
*ctx
, *n
;
4769 lockdep_assert_held(&wq_pool_mutex
);
4771 list_for_each_entry(wq
, &workqueues
, list
) {
4772 if (!(wq
->flags
& WQ_UNBOUND
))
4774 /* creating multiple pwqs breaks ordering guarantee */
4775 if (wq
->flags
& __WQ_ORDERED
)
4778 ctx
= apply_wqattrs_prepare(wq
, wq
->unbound_attrs
);
4784 list_add_tail(&ctx
->list
, &ctxs
);
4787 list_for_each_entry_safe(ctx
, n
, &ctxs
, list
) {
4789 apply_wqattrs_commit(ctx
);
4790 apply_wqattrs_cleanup(ctx
);
4797 * workqueue_set_unbound_cpumask - Set the low-level unbound cpumask
4798 * @cpumask: the cpumask to set
4800 * The low-level workqueues cpumask is a global cpumask that limits
4801 * the affinity of all unbound workqueues. This function check the @cpumask
4802 * and apply it to all unbound workqueues and updates all pwqs of them.
4804 * Retun: 0 - Success
4805 * -EINVAL - Invalid @cpumask
4806 * -ENOMEM - Failed to allocate memory for attrs or pwqs.
4808 int workqueue_set_unbound_cpumask(cpumask_var_t cpumask
)
4811 cpumask_var_t saved_cpumask
;
4813 if (!zalloc_cpumask_var(&saved_cpumask
, GFP_KERNEL
))
4816 cpumask_and(cpumask
, cpumask
, cpu_possible_mask
);
4817 if (!cpumask_empty(cpumask
)) {
4818 apply_wqattrs_lock();
4820 /* save the old wq_unbound_cpumask. */
4821 cpumask_copy(saved_cpumask
, wq_unbound_cpumask
);
4823 /* update wq_unbound_cpumask at first and apply it to wqs. */
4824 cpumask_copy(wq_unbound_cpumask
, cpumask
);
4825 ret
= workqueue_apply_unbound_cpumask();
4827 /* restore the wq_unbound_cpumask when failed. */
4829 cpumask_copy(wq_unbound_cpumask
, saved_cpumask
);
4831 apply_wqattrs_unlock();
4834 free_cpumask_var(saved_cpumask
);
4840 * Workqueues with WQ_SYSFS flag set is visible to userland via
4841 * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
4842 * following attributes.
4844 * per_cpu RO bool : whether the workqueue is per-cpu or unbound
4845 * max_active RW int : maximum number of in-flight work items
4847 * Unbound workqueues have the following extra attributes.
4849 * id RO int : the associated pool ID
4850 * nice RW int : nice value of the workers
4851 * cpumask RW mask : bitmask of allowed CPUs for the workers
4854 struct workqueue_struct
*wq
;
4858 static struct workqueue_struct
*dev_to_wq(struct device
*dev
)
4860 struct wq_device
*wq_dev
= container_of(dev
, struct wq_device
, dev
);
4865 static ssize_t
per_cpu_show(struct device
*dev
, struct device_attribute
*attr
,
4868 struct workqueue_struct
*wq
= dev_to_wq(dev
);
4870 return scnprintf(buf
, PAGE_SIZE
, "%d\n", (bool)!(wq
->flags
& WQ_UNBOUND
));
4872 static DEVICE_ATTR_RO(per_cpu
);
4874 static ssize_t
max_active_show(struct device
*dev
,
4875 struct device_attribute
*attr
, char *buf
)
4877 struct workqueue_struct
*wq
= dev_to_wq(dev
);
4879 return scnprintf(buf
, PAGE_SIZE
, "%d\n", wq
->saved_max_active
);
4882 static ssize_t
max_active_store(struct device
*dev
,
4883 struct device_attribute
*attr
, const char *buf
,
4886 struct workqueue_struct
*wq
= dev_to_wq(dev
);
4889 if (sscanf(buf
, "%d", &val
) != 1 || val
<= 0)
4892 workqueue_set_max_active(wq
, val
);
4895 static DEVICE_ATTR_RW(max_active
);
4897 static struct attribute
*wq_sysfs_attrs
[] = {
4898 &dev_attr_per_cpu
.attr
,
4899 &dev_attr_max_active
.attr
,
4902 ATTRIBUTE_GROUPS(wq_sysfs
);
4904 static ssize_t
wq_pool_ids_show(struct device
*dev
,
4905 struct device_attribute
*attr
, char *buf
)
4907 struct workqueue_struct
*wq
= dev_to_wq(dev
);
4908 const char *delim
= "";
4909 int node
, written
= 0;
4911 rcu_read_lock_sched();
4912 for_each_node(node
) {
4913 written
+= scnprintf(buf
+ written
, PAGE_SIZE
- written
,
4914 "%s%d:%d", delim
, node
,
4915 unbound_pwq_by_node(wq
, node
)->pool
->id
);
4918 written
+= scnprintf(buf
+ written
, PAGE_SIZE
- written
, "\n");
4919 rcu_read_unlock_sched();
4924 static ssize_t
wq_nice_show(struct device
*dev
, struct device_attribute
*attr
,
4927 struct workqueue_struct
*wq
= dev_to_wq(dev
);
4930 mutex_lock(&wq
->mutex
);
4931 written
= scnprintf(buf
, PAGE_SIZE
, "%d\n", wq
->unbound_attrs
->nice
);
4932 mutex_unlock(&wq
->mutex
);
4937 /* prepare workqueue_attrs for sysfs store operations */
4938 static struct workqueue_attrs
*wq_sysfs_prep_attrs(struct workqueue_struct
*wq
)
4940 struct workqueue_attrs
*attrs
;
4942 attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
4946 mutex_lock(&wq
->mutex
);
4947 copy_workqueue_attrs(attrs
, wq
->unbound_attrs
);
4948 mutex_unlock(&wq
->mutex
);
4952 static ssize_t
wq_nice_store(struct device
*dev
, struct device_attribute
*attr
,
4953 const char *buf
, size_t count
)
4955 struct workqueue_struct
*wq
= dev_to_wq(dev
);
4956 struct workqueue_attrs
*attrs
;
4959 attrs
= wq_sysfs_prep_attrs(wq
);
4963 if (sscanf(buf
, "%d", &attrs
->nice
) == 1 &&
4964 attrs
->nice
>= MIN_NICE
&& attrs
->nice
<= MAX_NICE
)
4965 ret
= apply_workqueue_attrs(wq
, attrs
);
4969 free_workqueue_attrs(attrs
);
4970 return ret
?: count
;
4973 static ssize_t
wq_cpumask_show(struct device
*dev
,
4974 struct device_attribute
*attr
, char *buf
)
4976 struct workqueue_struct
*wq
= dev_to_wq(dev
);
4979 mutex_lock(&wq
->mutex
);
4980 written
= scnprintf(buf
, PAGE_SIZE
, "%*pb\n",
4981 cpumask_pr_args(wq
->unbound_attrs
->cpumask
));
4982 mutex_unlock(&wq
->mutex
);
4986 static ssize_t
wq_cpumask_store(struct device
*dev
,
4987 struct device_attribute
*attr
,
4988 const char *buf
, size_t count
)
4990 struct workqueue_struct
*wq
= dev_to_wq(dev
);
4991 struct workqueue_attrs
*attrs
;
4994 attrs
= wq_sysfs_prep_attrs(wq
);
4998 ret
= cpumask_parse(buf
, attrs
->cpumask
);
5000 ret
= apply_workqueue_attrs(wq
, attrs
);
5002 free_workqueue_attrs(attrs
);
5003 return ret
?: count
;
5006 static ssize_t
wq_numa_show(struct device
*dev
, struct device_attribute
*attr
,
5009 struct workqueue_struct
*wq
= dev_to_wq(dev
);
5012 mutex_lock(&wq
->mutex
);
5013 written
= scnprintf(buf
, PAGE_SIZE
, "%d\n",
5014 !wq
->unbound_attrs
->no_numa
);
5015 mutex_unlock(&wq
->mutex
);
5020 static ssize_t
wq_numa_store(struct device
*dev
, struct device_attribute
*attr
,
5021 const char *buf
, size_t count
)
5023 struct workqueue_struct
*wq
= dev_to_wq(dev
);
5024 struct workqueue_attrs
*attrs
;
5027 attrs
= wq_sysfs_prep_attrs(wq
);
5032 if (sscanf(buf
, "%d", &v
) == 1) {
5033 attrs
->no_numa
= !v
;
5034 ret
= apply_workqueue_attrs(wq
, attrs
);
5037 free_workqueue_attrs(attrs
);
5038 return ret
?: count
;
5041 static struct device_attribute wq_sysfs_unbound_attrs
[] = {
5042 __ATTR(pool_ids
, 0444, wq_pool_ids_show
, NULL
),
5043 __ATTR(nice
, 0644, wq_nice_show
, wq_nice_store
),
5044 __ATTR(cpumask
, 0644, wq_cpumask_show
, wq_cpumask_store
),
5045 __ATTR(numa
, 0644, wq_numa_show
, wq_numa_store
),
5049 static struct bus_type wq_subsys
= {
5050 .name
= "workqueue",
5051 .dev_groups
= wq_sysfs_groups
,
5054 static ssize_t
wq_unbound_cpumask_show(struct device
*dev
,
5055 struct device_attribute
*attr
, char *buf
)
5059 mutex_lock(&wq_pool_mutex
);
5060 written
= scnprintf(buf
, PAGE_SIZE
, "%*pb\n",
5061 cpumask_pr_args(wq_unbound_cpumask
));
5062 mutex_unlock(&wq_pool_mutex
);
5067 static ssize_t
wq_unbound_cpumask_store(struct device
*dev
,
5068 struct device_attribute
*attr
, const char *buf
, size_t count
)
5070 cpumask_var_t cpumask
;
5073 if (!zalloc_cpumask_var(&cpumask
, GFP_KERNEL
))
5076 ret
= cpumask_parse(buf
, cpumask
);
5078 ret
= workqueue_set_unbound_cpumask(cpumask
);
5080 free_cpumask_var(cpumask
);
5081 return ret
? ret
: count
;
5084 static struct device_attribute wq_sysfs_cpumask_attr
=
5085 __ATTR(cpumask
, 0644, wq_unbound_cpumask_show
,
5086 wq_unbound_cpumask_store
);
5088 static int __init
wq_sysfs_init(void)
5092 err
= subsys_virtual_register(&wq_subsys
, NULL
);
5096 return device_create_file(wq_subsys
.dev_root
, &wq_sysfs_cpumask_attr
);
5098 core_initcall(wq_sysfs_init
);
5100 static void wq_device_release(struct device
*dev
)
5102 struct wq_device
*wq_dev
= container_of(dev
, struct wq_device
, dev
);
5108 * workqueue_sysfs_register - make a workqueue visible in sysfs
5109 * @wq: the workqueue to register
5111 * Expose @wq in sysfs under /sys/bus/workqueue/devices.
5112 * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
5113 * which is the preferred method.
5115 * Workqueue user should use this function directly iff it wants to apply
5116 * workqueue_attrs before making the workqueue visible in sysfs; otherwise,
5117 * apply_workqueue_attrs() may race against userland updating the
5120 * Return: 0 on success, -errno on failure.
5122 int workqueue_sysfs_register(struct workqueue_struct
*wq
)
5124 struct wq_device
*wq_dev
;
5128 * Adjusting max_active or creating new pwqs by applyting
5129 * attributes breaks ordering guarantee. Disallow exposing ordered
5132 if (WARN_ON(wq
->flags
& __WQ_ORDERED
))
5135 wq
->wq_dev
= wq_dev
= kzalloc(sizeof(*wq_dev
), GFP_KERNEL
);
5140 wq_dev
->dev
.bus
= &wq_subsys
;
5141 wq_dev
->dev
.init_name
= wq
->name
;
5142 wq_dev
->dev
.release
= wq_device_release
;
5145 * unbound_attrs are created separately. Suppress uevent until
5146 * everything is ready.
5148 dev_set_uevent_suppress(&wq_dev
->dev
, true);
5150 ret
= device_register(&wq_dev
->dev
);
5157 if (wq
->flags
& WQ_UNBOUND
) {
5158 struct device_attribute
*attr
;
5160 for (attr
= wq_sysfs_unbound_attrs
; attr
->attr
.name
; attr
++) {
5161 ret
= device_create_file(&wq_dev
->dev
, attr
);
5163 device_unregister(&wq_dev
->dev
);
5170 dev_set_uevent_suppress(&wq_dev
->dev
, false);
5171 kobject_uevent(&wq_dev
->dev
.kobj
, KOBJ_ADD
);
5176 * workqueue_sysfs_unregister - undo workqueue_sysfs_register()
5177 * @wq: the workqueue to unregister
5179 * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
5181 static void workqueue_sysfs_unregister(struct workqueue_struct
*wq
)
5183 struct wq_device
*wq_dev
= wq
->wq_dev
;
5189 device_unregister(&wq_dev
->dev
);
5191 #else /* CONFIG_SYSFS */
5192 static void workqueue_sysfs_unregister(struct workqueue_struct
*wq
) { }
5193 #endif /* CONFIG_SYSFS */
5195 static void __init
wq_numa_init(void)
5200 if (num_possible_nodes() <= 1)
5203 if (wq_disable_numa
) {
5204 pr_info("workqueue: NUMA affinity support disabled\n");
5208 wq_update_unbound_numa_attrs_buf
= alloc_workqueue_attrs(GFP_KERNEL
);
5209 BUG_ON(!wq_update_unbound_numa_attrs_buf
);
5212 * We want masks of possible CPUs of each node which isn't readily
5213 * available. Build one from cpu_to_node() which should have been
5214 * fully initialized by now.
5216 tbl
= kzalloc(nr_node_ids
* sizeof(tbl
[0]), GFP_KERNEL
);
5220 BUG_ON(!zalloc_cpumask_var_node(&tbl
[node
], GFP_KERNEL
,
5221 node_online(node
) ? node
: NUMA_NO_NODE
));
5223 for_each_possible_cpu(cpu
) {
5224 node
= cpu_to_node(cpu
);
5225 if (WARN_ON(node
== NUMA_NO_NODE
)) {
5226 pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu
);
5227 /* happens iff arch is bonkers, let's just proceed */
5230 cpumask_set_cpu(cpu
, tbl
[node
]);
5233 wq_numa_possible_cpumask
= tbl
;
5234 wq_numa_enabled
= true;
5237 static int __init
init_workqueues(void)
5239 int std_nice
[NR_STD_WORKER_POOLS
] = { 0, HIGHPRI_NICE_LEVEL
};
5242 WARN_ON(__alignof__(struct pool_workqueue
) < __alignof__(long long));
5244 BUG_ON(!alloc_cpumask_var(&wq_unbound_cpumask
, GFP_KERNEL
));
5245 cpumask_copy(wq_unbound_cpumask
, cpu_possible_mask
);
5247 pwq_cache
= KMEM_CACHE(pool_workqueue
, SLAB_PANIC
);
5249 cpu_notifier(workqueue_cpu_up_callback
, CPU_PRI_WORKQUEUE_UP
);
5250 hotcpu_notifier(workqueue_cpu_down_callback
, CPU_PRI_WORKQUEUE_DOWN
);
5254 /* initialize CPU pools */
5255 for_each_possible_cpu(cpu
) {
5256 struct worker_pool
*pool
;
5259 for_each_cpu_worker_pool(pool
, cpu
) {
5260 BUG_ON(init_worker_pool(pool
));
5262 cpumask_copy(pool
->attrs
->cpumask
, cpumask_of(cpu
));
5263 pool
->attrs
->nice
= std_nice
[i
++];
5264 pool
->node
= cpu_to_node(cpu
);
5267 mutex_lock(&wq_pool_mutex
);
5268 BUG_ON(worker_pool_assign_id(pool
));
5269 mutex_unlock(&wq_pool_mutex
);
5273 /* create the initial worker */
5274 for_each_online_cpu(cpu
) {
5275 struct worker_pool
*pool
;
5277 for_each_cpu_worker_pool(pool
, cpu
) {
5278 pool
->flags
&= ~POOL_DISASSOCIATED
;
5279 BUG_ON(!create_worker(pool
));
5283 /* create default unbound and ordered wq attrs */
5284 for (i
= 0; i
< NR_STD_WORKER_POOLS
; i
++) {
5285 struct workqueue_attrs
*attrs
;
5287 BUG_ON(!(attrs
= alloc_workqueue_attrs(GFP_KERNEL
)));
5288 attrs
->nice
= std_nice
[i
];
5289 unbound_std_wq_attrs
[i
] = attrs
;
5292 * An ordered wq should have only one pwq as ordering is
5293 * guaranteed by max_active which is enforced by pwqs.
5294 * Turn off NUMA so that dfl_pwq is used for all nodes.
5296 BUG_ON(!(attrs
= alloc_workqueue_attrs(GFP_KERNEL
)));
5297 attrs
->nice
= std_nice
[i
];
5298 attrs
->no_numa
= true;
5299 ordered_wq_attrs
[i
] = attrs
;
5302 system_wq
= alloc_workqueue("events", 0, 0);
5303 system_highpri_wq
= alloc_workqueue("events_highpri", WQ_HIGHPRI
, 0);
5304 system_long_wq
= alloc_workqueue("events_long", 0, 0);
5305 system_unbound_wq
= alloc_workqueue("events_unbound", WQ_UNBOUND
,
5306 WQ_UNBOUND_MAX_ACTIVE
);
5307 system_freezable_wq
= alloc_workqueue("events_freezable",
5309 system_power_efficient_wq
= alloc_workqueue("events_power_efficient",
5310 WQ_POWER_EFFICIENT
, 0);
5311 system_freezable_power_efficient_wq
= alloc_workqueue("events_freezable_power_efficient",
5312 WQ_FREEZABLE
| WQ_POWER_EFFICIENT
,
5314 BUG_ON(!system_wq
|| !system_highpri_wq
|| !system_long_wq
||
5315 !system_unbound_wq
|| !system_freezable_wq
||
5316 !system_power_efficient_wq
||
5317 !system_freezable_power_efficient_wq
);
5320 early_initcall(init_workqueues
);