2 * kernel/workqueue.c - generic async execution with shared worker pool
4 * Copyright (C) 2002 Ingo Molnar
6 * Derived from the taskqueue/keventd code by:
7 * David Woodhouse <dwmw2@infradead.org>
9 * Kai Petzke <wpp@marie.physik.tu-berlin.de>
10 * Theodore Ts'o <tytso@mit.edu>
12 * Made to use alloc_percpu by Christoph Lameter.
14 * Copyright (C) 2010 SUSE Linux Products GmbH
15 * Copyright (C) 2010 Tejun Heo <tj@kernel.org>
17 * This is the generic async execution mechanism. Work items as are
18 * executed in process context. The worker pool is shared and
19 * automatically managed. There is one worker pool for each CPU and
20 * one extra for works which are better served by workers which are
21 * not bound to any specific CPU.
23 * Please read Documentation/workqueue.txt for details.
26 #include <linux/export.h>
27 #include <linux/kernel.h>
28 #include <linux/sched.h>
29 #include <linux/init.h>
30 #include <linux/signal.h>
31 #include <linux/completion.h>
32 #include <linux/workqueue.h>
33 #include <linux/slab.h>
34 #include <linux/cpu.h>
35 #include <linux/notifier.h>
36 #include <linux/kthread.h>
37 #include <linux/hardirq.h>
38 #include <linux/mempolicy.h>
39 #include <linux/freezer.h>
40 #include <linux/kallsyms.h>
41 #include <linux/debug_locks.h>
42 #include <linux/lockdep.h>
43 #include <linux/idr.h>
44 #include <linux/jhash.h>
45 #include <linux/hashtable.h>
46 #include <linux/rculist.h>
47 #include <linux/nodemask.h>
48 #include <linux/moduleparam.h>
49 #include <linux/uaccess.h>
51 #include "workqueue_internal.h"
57 * A bound pool is either associated or disassociated with its CPU.
58 * While associated (!DISASSOCIATED), all workers are bound to the
59 * CPU and none has %WORKER_UNBOUND set and concurrency management
62 * While DISASSOCIATED, the cpu may be offline and all workers have
63 * %WORKER_UNBOUND set and concurrency management disabled, and may
64 * be executing on any CPU. The pool behaves as an unbound one.
66 * Note that DISASSOCIATED should be flipped only while holding
67 * manager_mutex to avoid changing binding state while
68 * create_worker() is in progress.
70 POOL_MANAGE_WORKERS
= 1 << 0, /* need to manage workers */
71 POOL_DISASSOCIATED
= 1 << 2, /* cpu can't serve workers */
72 POOL_FREEZING
= 1 << 3, /* freeze in progress */
75 WORKER_STARTED
= 1 << 0, /* started */
76 WORKER_DIE
= 1 << 1, /* die die die */
77 WORKER_IDLE
= 1 << 2, /* is idle */
78 WORKER_PREP
= 1 << 3, /* preparing to run works */
79 WORKER_CPU_INTENSIVE
= 1 << 6, /* cpu intensive */
80 WORKER_UNBOUND
= 1 << 7, /* worker is unbound */
81 WORKER_REBOUND
= 1 << 8, /* worker was rebound */
83 WORKER_NOT_RUNNING
= WORKER_PREP
| WORKER_CPU_INTENSIVE
|
84 WORKER_UNBOUND
| WORKER_REBOUND
,
86 NR_STD_WORKER_POOLS
= 2, /* # standard pools per cpu */
88 UNBOUND_POOL_HASH_ORDER
= 6, /* hashed by pool->attrs */
89 BUSY_WORKER_HASH_ORDER
= 6, /* 64 pointers */
91 MAX_IDLE_WORKERS_RATIO
= 4, /* 1/4 of busy can be idle */
92 IDLE_WORKER_TIMEOUT
= 300 * HZ
, /* keep idle ones for 5 mins */
94 MAYDAY_INITIAL_TIMEOUT
= HZ
/ 100 >= 2 ? HZ
/ 100 : 2,
95 /* call for help after 10ms
97 MAYDAY_INTERVAL
= HZ
/ 10, /* and then every 100ms */
98 CREATE_COOLDOWN
= HZ
, /* time to breath after fail */
101 * Rescue workers are used only on emergencies and shared by
102 * all cpus. Give -20.
104 RESCUER_NICE_LEVEL
= -20,
105 HIGHPRI_NICE_LEVEL
= -20,
111 * Structure fields follow one of the following exclusion rules.
113 * I: Modifiable by initialization/destruction paths and read-only for
116 * P: Preemption protected. Disabling preemption is enough and should
117 * only be modified and accessed from the local cpu.
119 * L: pool->lock protected. Access with pool->lock held.
121 * X: During normal operation, modification requires pool->lock and should
122 * be done only from local cpu. Either disabling preemption on local
123 * cpu or grabbing pool->lock is enough for read access. If
124 * POOL_DISASSOCIATED is set, it's identical to L.
126 * MG: pool->manager_mutex and pool->lock protected. Writes require both
127 * locks. Reads can happen under either lock.
129 * PL: wq_pool_mutex protected.
131 * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads.
133 * WQ: wq->mutex protected.
135 * WR: wq->mutex protected for writes. Sched-RCU protected for reads.
137 * MD: wq_mayday_lock protected.
140 /* struct worker is defined in workqueue_internal.h */
143 spinlock_t lock
; /* the pool lock */
144 int cpu
; /* I: the associated cpu */
145 int node
; /* I: the associated node ID */
146 int id
; /* I: pool ID */
147 unsigned int flags
; /* X: flags */
149 struct list_head worklist
; /* L: list of pending works */
150 int nr_workers
; /* L: total number of workers */
152 /* nr_idle includes the ones off idle_list for rebinding */
153 int nr_idle
; /* L: currently idle ones */
155 struct list_head idle_list
; /* X: list of idle workers */
156 struct timer_list idle_timer
; /* L: worker idle timeout */
157 struct timer_list mayday_timer
; /* L: SOS timer for workers */
159 /* a workers is either on busy_hash or idle_list, or the manager */
160 DECLARE_HASHTABLE(busy_hash
, BUSY_WORKER_HASH_ORDER
);
161 /* L: hash of busy workers */
163 /* see manage_workers() for details on the two manager mutexes */
164 struct mutex manager_arb
; /* manager arbitration */
165 struct mutex manager_mutex
; /* manager exclusion */
166 struct idr worker_idr
; /* MG: worker IDs and iteration */
168 struct workqueue_attrs
*attrs
; /* I: worker attributes */
169 struct hlist_node hash_node
; /* PL: unbound_pool_hash node */
170 int refcnt
; /* PL: refcnt for unbound pools */
173 * The current concurrency level. As it's likely to be accessed
174 * from other CPUs during try_to_wake_up(), put it in a separate
177 atomic_t nr_running ____cacheline_aligned_in_smp
;
180 * Destruction of pool is sched-RCU protected to allow dereferences
181 * from get_work_pool().
184 } ____cacheline_aligned_in_smp
;
187 * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS
188 * of work_struct->data are used for flags and the remaining high bits
189 * point to the pwq; thus, pwqs need to be aligned at two's power of the
190 * number of flag bits.
192 struct pool_workqueue
{
193 struct worker_pool
*pool
; /* I: the associated pool */
194 struct workqueue_struct
*wq
; /* I: the owning workqueue */
195 int work_color
; /* L: current color */
196 int flush_color
; /* L: flushing color */
197 int refcnt
; /* L: reference count */
198 int nr_in_flight
[WORK_NR_COLORS
];
199 /* L: nr of in_flight works */
200 int nr_active
; /* L: nr of active works */
201 int max_active
; /* L: max active works */
202 struct list_head delayed_works
; /* L: delayed works */
203 struct list_head pwqs_node
; /* WR: node on wq->pwqs */
204 struct list_head mayday_node
; /* MD: node on wq->maydays */
207 * Release of unbound pwq is punted to system_wq. See put_pwq()
208 * and pwq_unbound_release_workfn() for details. pool_workqueue
209 * itself is also sched-RCU protected so that the first pwq can be
210 * determined without grabbing wq->mutex.
212 struct work_struct unbound_release_work
;
214 } __aligned(1 << WORK_STRUCT_FLAG_BITS
);
217 * Structure used to wait for workqueue flush.
220 struct list_head list
; /* WQ: list of flushers */
221 int flush_color
; /* WQ: flush color waiting for */
222 struct completion done
; /* flush completion */
228 * The externally visible workqueue. It relays the issued work items to
229 * the appropriate worker_pool through its pool_workqueues.
231 struct workqueue_struct
{
232 struct list_head pwqs
; /* WR: all pwqs of this wq */
233 struct list_head list
; /* PL: list of all workqueues */
235 struct mutex mutex
; /* protects this wq */
236 int work_color
; /* WQ: current work color */
237 int flush_color
; /* WQ: current flush color */
238 atomic_t nr_pwqs_to_flush
; /* flush in progress */
239 struct wq_flusher
*first_flusher
; /* WQ: first flusher */
240 struct list_head flusher_queue
; /* WQ: flush waiters */
241 struct list_head flusher_overflow
; /* WQ: flush overflow list */
243 struct list_head maydays
; /* MD: pwqs requesting rescue */
244 struct worker
*rescuer
; /* I: rescue worker */
246 int nr_drainers
; /* WQ: drain in progress */
247 int saved_max_active
; /* WQ: saved pwq max_active */
249 struct workqueue_attrs
*unbound_attrs
; /* WQ: only for unbound wqs */
250 struct pool_workqueue
*dfl_pwq
; /* WQ: only for unbound wqs */
253 struct wq_device
*wq_dev
; /* I: for sysfs interface */
255 #ifdef CONFIG_LOCKDEP
256 struct lockdep_map lockdep_map
;
258 char name
[WQ_NAME_LEN
]; /* I: workqueue name */
260 /* hot fields used during command issue, aligned to cacheline */
261 unsigned int flags ____cacheline_aligned
; /* WQ: WQ_* flags */
262 struct pool_workqueue __percpu
*cpu_pwqs
; /* I: per-cpu pwqs */
263 struct pool_workqueue __rcu
*numa_pwq_tbl
[]; /* FR: unbound pwqs indexed by node */
266 static struct kmem_cache
*pwq_cache
;
268 static int wq_numa_tbl_len
; /* highest possible NUMA node id + 1 */
269 static cpumask_var_t
*wq_numa_possible_cpumask
;
270 /* possible CPUs of each node */
272 static bool wq_disable_numa
;
273 module_param_named(disable_numa
, wq_disable_numa
, bool, 0444);
275 /* see the comment above the definition of WQ_POWER_EFFICIENT */
276 #ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT
277 static bool wq_power_efficient
= true;
279 static bool wq_power_efficient
;
282 module_param_named(power_efficient
, wq_power_efficient
, bool, 0444);
284 static bool wq_numa_enabled
; /* unbound NUMA affinity enabled */
286 /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */
287 static struct workqueue_attrs
*wq_update_unbound_numa_attrs_buf
;
289 static DEFINE_MUTEX(wq_pool_mutex
); /* protects pools and workqueues list */
290 static DEFINE_SPINLOCK(wq_mayday_lock
); /* protects wq->maydays list */
292 static LIST_HEAD(workqueues
); /* PL: list of all workqueues */
293 static bool workqueue_freezing
; /* PL: have wqs started freezing? */
295 /* the per-cpu worker pools */
296 static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool
[NR_STD_WORKER_POOLS
],
299 static DEFINE_IDR(worker_pool_idr
); /* PR: idr of all pools */
301 /* PL: hash of all unbound pools keyed by pool->attrs */
302 static DEFINE_HASHTABLE(unbound_pool_hash
, UNBOUND_POOL_HASH_ORDER
);
304 /* I: attributes used when instantiating standard unbound pools on demand */
305 static struct workqueue_attrs
*unbound_std_wq_attrs
[NR_STD_WORKER_POOLS
];
307 struct workqueue_struct
*system_wq __read_mostly
;
308 EXPORT_SYMBOL(system_wq
);
309 struct workqueue_struct
*system_highpri_wq __read_mostly
;
310 EXPORT_SYMBOL_GPL(system_highpri_wq
);
311 struct workqueue_struct
*system_long_wq __read_mostly
;
312 EXPORT_SYMBOL_GPL(system_long_wq
);
313 struct workqueue_struct
*system_unbound_wq __read_mostly
;
314 EXPORT_SYMBOL_GPL(system_unbound_wq
);
315 struct workqueue_struct
*system_freezable_wq __read_mostly
;
316 EXPORT_SYMBOL_GPL(system_freezable_wq
);
317 struct workqueue_struct
*system_power_efficient_wq __read_mostly
;
318 EXPORT_SYMBOL_GPL(system_power_efficient_wq
);
319 struct workqueue_struct
*system_freezable_power_efficient_wq __read_mostly
;
320 EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq
);
322 static int worker_thread(void *__worker
);
323 static void copy_workqueue_attrs(struct workqueue_attrs
*to
,
324 const struct workqueue_attrs
*from
);
326 #define CREATE_TRACE_POINTS
327 #include <trace/events/workqueue.h>
329 #define assert_rcu_or_pool_mutex() \
330 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
331 lockdep_is_held(&wq_pool_mutex), \
332 "sched RCU or wq_pool_mutex should be held")
334 #define assert_rcu_or_wq_mutex(wq) \
335 rcu_lockdep_assert(rcu_read_lock_sched_held() || \
336 lockdep_is_held(&wq->mutex), \
337 "sched RCU or wq->mutex should be held")
339 #ifdef CONFIG_LOCKDEP
340 #define assert_manager_or_pool_lock(pool) \
341 WARN_ONCE(debug_locks && \
342 !lockdep_is_held(&(pool)->manager_mutex) && \
343 !lockdep_is_held(&(pool)->lock), \
344 "pool->manager_mutex or ->lock should be held")
346 #define assert_manager_or_pool_lock(pool) do { } while (0)
349 #define for_each_cpu_worker_pool(pool, cpu) \
350 for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \
351 (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \
355 * for_each_pool - iterate through all worker_pools in the system
356 * @pool: iteration cursor
357 * @pi: integer used for iteration
359 * This must be called either with wq_pool_mutex held or sched RCU read
360 * locked. If the pool needs to be used beyond the locking in effect, the
361 * caller is responsible for guaranteeing that the pool stays online.
363 * The if/else clause exists only for the lockdep assertion and can be
366 #define for_each_pool(pool, pi) \
367 idr_for_each_entry(&worker_pool_idr, pool, pi) \
368 if (({ assert_rcu_or_pool_mutex(); false; })) { } \
372 * for_each_pool_worker - iterate through all workers of a worker_pool
373 * @worker: iteration cursor
374 * @wi: integer used for iteration
375 * @pool: worker_pool to iterate workers of
377 * This must be called with either @pool->manager_mutex or ->lock held.
379 * The if/else clause exists only for the lockdep assertion and can be
382 #define for_each_pool_worker(worker, wi, pool) \
383 idr_for_each_entry(&(pool)->worker_idr, (worker), (wi)) \
384 if (({ assert_manager_or_pool_lock((pool)); false; })) { } \
388 * for_each_pwq - iterate through all pool_workqueues of the specified workqueue
389 * @pwq: iteration cursor
390 * @wq: the target workqueue
392 * This must be called either with wq->mutex held or sched RCU read locked.
393 * If the pwq needs to be used beyond the locking in effect, the caller is
394 * responsible for guaranteeing that the pwq stays online.
396 * The if/else clause exists only for the lockdep assertion and can be
399 #define for_each_pwq(pwq, wq) \
400 list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \
401 if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \
404 #ifdef CONFIG_DEBUG_OBJECTS_WORK
406 static struct debug_obj_descr work_debug_descr
;
408 static void *work_debug_hint(void *addr
)
410 return ((struct work_struct
*) addr
)->func
;
414 * fixup_init is called when:
415 * - an active object is initialized
417 static int work_fixup_init(void *addr
, enum debug_obj_state state
)
419 struct work_struct
*work
= addr
;
422 case ODEBUG_STATE_ACTIVE
:
423 cancel_work_sync(work
);
424 debug_object_init(work
, &work_debug_descr
);
432 * fixup_activate is called when:
433 * - an active object is activated
434 * - an unknown object is activated (might be a statically initialized object)
436 static int work_fixup_activate(void *addr
, enum debug_obj_state state
)
438 struct work_struct
*work
= addr
;
442 case ODEBUG_STATE_NOTAVAILABLE
:
444 * This is not really a fixup. The work struct was
445 * statically initialized. We just make sure that it
446 * is tracked in the object tracker.
448 if (test_bit(WORK_STRUCT_STATIC_BIT
, work_data_bits(work
))) {
449 debug_object_init(work
, &work_debug_descr
);
450 debug_object_activate(work
, &work_debug_descr
);
456 case ODEBUG_STATE_ACTIVE
:
465 * fixup_free is called when:
466 * - an active object is freed
468 static int work_fixup_free(void *addr
, enum debug_obj_state state
)
470 struct work_struct
*work
= addr
;
473 case ODEBUG_STATE_ACTIVE
:
474 cancel_work_sync(work
);
475 debug_object_free(work
, &work_debug_descr
);
482 static struct debug_obj_descr work_debug_descr
= {
483 .name
= "work_struct",
484 .debug_hint
= work_debug_hint
,
485 .fixup_init
= work_fixup_init
,
486 .fixup_activate
= work_fixup_activate
,
487 .fixup_free
= work_fixup_free
,
490 static inline void debug_work_activate(struct work_struct
*work
)
492 debug_object_activate(work
, &work_debug_descr
);
495 static inline void debug_work_deactivate(struct work_struct
*work
)
497 debug_object_deactivate(work
, &work_debug_descr
);
500 void __init_work(struct work_struct
*work
, int onstack
)
503 debug_object_init_on_stack(work
, &work_debug_descr
);
505 debug_object_init(work
, &work_debug_descr
);
507 EXPORT_SYMBOL_GPL(__init_work
);
509 void destroy_work_on_stack(struct work_struct
*work
)
511 debug_object_free(work
, &work_debug_descr
);
513 EXPORT_SYMBOL_GPL(destroy_work_on_stack
);
516 static inline void debug_work_activate(struct work_struct
*work
) { }
517 static inline void debug_work_deactivate(struct work_struct
*work
) { }
520 /* allocate ID and assign it to @pool */
521 static int worker_pool_assign_id(struct worker_pool
*pool
)
525 lockdep_assert_held(&wq_pool_mutex
);
527 ret
= idr_alloc(&worker_pool_idr
, pool
, 0, 0, GFP_KERNEL
);
536 * unbound_pwq_by_node - return the unbound pool_workqueue for the given node
537 * @wq: the target workqueue
540 * This must be called either with pwq_lock held or sched RCU read locked.
541 * If the pwq needs to be used beyond the locking in effect, the caller is
542 * responsible for guaranteeing that the pwq stays online.
544 static struct pool_workqueue
*unbound_pwq_by_node(struct workqueue_struct
*wq
,
547 assert_rcu_or_wq_mutex(wq
);
548 return rcu_dereference_raw(wq
->numa_pwq_tbl
[node
]);
551 static unsigned int work_color_to_flags(int color
)
553 return color
<< WORK_STRUCT_COLOR_SHIFT
;
556 static int get_work_color(struct work_struct
*work
)
558 return (*work_data_bits(work
) >> WORK_STRUCT_COLOR_SHIFT
) &
559 ((1 << WORK_STRUCT_COLOR_BITS
) - 1);
562 static int work_next_color(int color
)
564 return (color
+ 1) % WORK_NR_COLORS
;
568 * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data
569 * contain the pointer to the queued pwq. Once execution starts, the flag
570 * is cleared and the high bits contain OFFQ flags and pool ID.
572 * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling()
573 * and clear_work_data() can be used to set the pwq, pool or clear
574 * work->data. These functions should only be called while the work is
575 * owned - ie. while the PENDING bit is set.
577 * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq
578 * corresponding to a work. Pool is available once the work has been
579 * queued anywhere after initialization until it is sync canceled. pwq is
580 * available only while the work item is queued.
582 * %WORK_OFFQ_CANCELING is used to mark a work item which is being
583 * canceled. While being canceled, a work item may have its PENDING set
584 * but stay off timer and worklist for arbitrarily long and nobody should
585 * try to steal the PENDING bit.
587 static inline void set_work_data(struct work_struct
*work
, unsigned long data
,
590 WARN_ON_ONCE(!work_pending(work
));
591 atomic_long_set(&work
->data
, data
| flags
| work_static(work
));
594 static void set_work_pwq(struct work_struct
*work
, struct pool_workqueue
*pwq
,
595 unsigned long extra_flags
)
597 set_work_data(work
, (unsigned long)pwq
,
598 WORK_STRUCT_PENDING
| WORK_STRUCT_PWQ
| extra_flags
);
601 static void set_work_pool_and_keep_pending(struct work_struct
*work
,
604 set_work_data(work
, (unsigned long)pool_id
<< WORK_OFFQ_POOL_SHIFT
,
605 WORK_STRUCT_PENDING
);
608 static void set_work_pool_and_clear_pending(struct work_struct
*work
,
612 * The following wmb is paired with the implied mb in
613 * test_and_set_bit(PENDING) and ensures all updates to @work made
614 * here are visible to and precede any updates by the next PENDING
618 set_work_data(work
, (unsigned long)pool_id
<< WORK_OFFQ_POOL_SHIFT
, 0);
621 static void clear_work_data(struct work_struct
*work
)
623 smp_wmb(); /* see set_work_pool_and_clear_pending() */
624 set_work_data(work
, WORK_STRUCT_NO_POOL
, 0);
627 static struct pool_workqueue
*get_work_pwq(struct work_struct
*work
)
629 unsigned long data
= atomic_long_read(&work
->data
);
631 if (data
& WORK_STRUCT_PWQ
)
632 return (void *)(data
& WORK_STRUCT_WQ_DATA_MASK
);
638 * get_work_pool - return the worker_pool a given work was associated with
639 * @work: the work item of interest
641 * Return the worker_pool @work was last associated with. %NULL if none.
643 * Pools are created and destroyed under wq_pool_mutex, and allows read
644 * access under sched-RCU read lock. As such, this function should be
645 * called under wq_pool_mutex or with preemption disabled.
647 * All fields of the returned pool are accessible as long as the above
648 * mentioned locking is in effect. If the returned pool needs to be used
649 * beyond the critical section, the caller is responsible for ensuring the
650 * returned pool is and stays online.
652 static struct worker_pool
*get_work_pool(struct work_struct
*work
)
654 unsigned long data
= atomic_long_read(&work
->data
);
657 assert_rcu_or_pool_mutex();
659 if (data
& WORK_STRUCT_PWQ
)
660 return ((struct pool_workqueue
*)
661 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
;
663 pool_id
= data
>> WORK_OFFQ_POOL_SHIFT
;
664 if (pool_id
== WORK_OFFQ_POOL_NONE
)
667 return idr_find(&worker_pool_idr
, pool_id
);
671 * get_work_pool_id - return the worker pool ID a given work is associated with
672 * @work: the work item of interest
674 * Return the worker_pool ID @work was last associated with.
675 * %WORK_OFFQ_POOL_NONE if none.
677 static int get_work_pool_id(struct work_struct
*work
)
679 unsigned long data
= atomic_long_read(&work
->data
);
681 if (data
& WORK_STRUCT_PWQ
)
682 return ((struct pool_workqueue
*)
683 (data
& WORK_STRUCT_WQ_DATA_MASK
))->pool
->id
;
685 return data
>> WORK_OFFQ_POOL_SHIFT
;
688 static void mark_work_canceling(struct work_struct
*work
)
690 unsigned long pool_id
= get_work_pool_id(work
);
692 pool_id
<<= WORK_OFFQ_POOL_SHIFT
;
693 set_work_data(work
, pool_id
| WORK_OFFQ_CANCELING
, WORK_STRUCT_PENDING
);
696 static bool work_is_canceling(struct work_struct
*work
)
698 unsigned long data
= atomic_long_read(&work
->data
);
700 return !(data
& WORK_STRUCT_PWQ
) && (data
& WORK_OFFQ_CANCELING
);
704 * Policy functions. These define the policies on how the global worker
705 * pools are managed. Unless noted otherwise, these functions assume that
706 * they're being called with pool->lock held.
709 static bool __need_more_worker(struct worker_pool
*pool
)
711 return !atomic_read(&pool
->nr_running
);
715 * Need to wake up a worker? Called from anything but currently
718 * Note that, because unbound workers never contribute to nr_running, this
719 * function will always return %true for unbound pools as long as the
720 * worklist isn't empty.
722 static bool need_more_worker(struct worker_pool
*pool
)
724 return !list_empty(&pool
->worklist
) && __need_more_worker(pool
);
727 /* Can I start working? Called from busy but !running workers. */
728 static bool may_start_working(struct worker_pool
*pool
)
730 return pool
->nr_idle
;
733 /* Do I need to keep working? Called from currently running workers. */
734 static bool keep_working(struct worker_pool
*pool
)
736 return !list_empty(&pool
->worklist
) &&
737 atomic_read(&pool
->nr_running
) <= 1;
740 /* Do we need a new worker? Called from manager. */
741 static bool need_to_create_worker(struct worker_pool
*pool
)
743 return need_more_worker(pool
) && !may_start_working(pool
);
746 /* Do I need to be the manager? */
747 static bool need_to_manage_workers(struct worker_pool
*pool
)
749 return need_to_create_worker(pool
) ||
750 (pool
->flags
& POOL_MANAGE_WORKERS
);
753 /* Do we have too many workers and should some go away? */
754 static bool too_many_workers(struct worker_pool
*pool
)
756 bool managing
= mutex_is_locked(&pool
->manager_arb
);
757 int nr_idle
= pool
->nr_idle
+ managing
; /* manager is considered idle */
758 int nr_busy
= pool
->nr_workers
- nr_idle
;
761 * nr_idle and idle_list may disagree if idle rebinding is in
762 * progress. Never return %true if idle_list is empty.
764 if (list_empty(&pool
->idle_list
))
767 return nr_idle
> 2 && (nr_idle
- 2) * MAX_IDLE_WORKERS_RATIO
>= nr_busy
;
774 /* Return the first worker. Safe with preemption disabled */
775 static struct worker
*first_worker(struct worker_pool
*pool
)
777 if (unlikely(list_empty(&pool
->idle_list
)))
780 return list_first_entry(&pool
->idle_list
, struct worker
, entry
);
784 * wake_up_worker - wake up an idle worker
785 * @pool: worker pool to wake worker from
787 * Wake up the first idle worker of @pool.
790 * spin_lock_irq(pool->lock).
792 static void wake_up_worker(struct worker_pool
*pool
)
794 struct worker
*worker
= first_worker(pool
);
797 wake_up_process(worker
->task
);
801 * wq_worker_waking_up - a worker is waking up
802 * @task: task waking up
803 * @cpu: CPU @task is waking up to
805 * This function is called during try_to_wake_up() when a worker is
809 * spin_lock_irq(rq->lock)
811 void wq_worker_waking_up(struct task_struct
*task
, int cpu
)
813 struct worker
*worker
= kthread_data(task
);
815 if (!(worker
->flags
& WORKER_NOT_RUNNING
)) {
816 WARN_ON_ONCE(worker
->pool
->cpu
!= cpu
);
817 atomic_inc(&worker
->pool
->nr_running
);
822 * wq_worker_sleeping - a worker is going to sleep
823 * @task: task going to sleep
824 * @cpu: CPU in question, must be the current CPU number
826 * This function is called during schedule() when a busy worker is
827 * going to sleep. Worker on the same cpu can be woken up by
828 * returning pointer to its task.
831 * spin_lock_irq(rq->lock)
834 * Worker task on @cpu to wake up, %NULL if none.
836 struct task_struct
*wq_worker_sleeping(struct task_struct
*task
, int cpu
)
838 struct worker
*worker
= kthread_data(task
), *to_wakeup
= NULL
;
839 struct worker_pool
*pool
;
842 * Rescuers, which may not have all the fields set up like normal
843 * workers, also reach here, let's not access anything before
844 * checking NOT_RUNNING.
846 if (worker
->flags
& WORKER_NOT_RUNNING
)
851 /* this can only happen on the local cpu */
852 if (WARN_ON_ONCE(cpu
!= raw_smp_processor_id()))
856 * The counterpart of the following dec_and_test, implied mb,
857 * worklist not empty test sequence is in insert_work().
858 * Please read comment there.
860 * NOT_RUNNING is clear. This means that we're bound to and
861 * running on the local cpu w/ rq lock held and preemption
862 * disabled, which in turn means that none else could be
863 * manipulating idle_list, so dereferencing idle_list without pool
866 if (atomic_dec_and_test(&pool
->nr_running
) &&
867 !list_empty(&pool
->worklist
))
868 to_wakeup
= first_worker(pool
);
869 return to_wakeup
? to_wakeup
->task
: NULL
;
873 * worker_set_flags - set worker flags and adjust nr_running accordingly
875 * @flags: flags to set
876 * @wakeup: wakeup an idle worker if necessary
878 * Set @flags in @worker->flags and adjust nr_running accordingly. If
879 * nr_running becomes zero and @wakeup is %true, an idle worker is
883 * spin_lock_irq(pool->lock)
885 static inline void worker_set_flags(struct worker
*worker
, unsigned int flags
,
888 struct worker_pool
*pool
= worker
->pool
;
890 WARN_ON_ONCE(worker
->task
!= current
);
893 * If transitioning into NOT_RUNNING, adjust nr_running and
894 * wake up an idle worker as necessary if requested by
897 if ((flags
& WORKER_NOT_RUNNING
) &&
898 !(worker
->flags
& WORKER_NOT_RUNNING
)) {
900 if (atomic_dec_and_test(&pool
->nr_running
) &&
901 !list_empty(&pool
->worklist
))
902 wake_up_worker(pool
);
904 atomic_dec(&pool
->nr_running
);
907 worker
->flags
|= flags
;
911 * worker_clr_flags - clear worker flags and adjust nr_running accordingly
913 * @flags: flags to clear
915 * Clear @flags in @worker->flags and adjust nr_running accordingly.
918 * spin_lock_irq(pool->lock)
920 static inline void worker_clr_flags(struct worker
*worker
, unsigned int flags
)
922 struct worker_pool
*pool
= worker
->pool
;
923 unsigned int oflags
= worker
->flags
;
925 WARN_ON_ONCE(worker
->task
!= current
);
927 worker
->flags
&= ~flags
;
930 * If transitioning out of NOT_RUNNING, increment nr_running. Note
931 * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask
932 * of multiple flags, not a single flag.
934 if ((flags
& WORKER_NOT_RUNNING
) && (oflags
& WORKER_NOT_RUNNING
))
935 if (!(worker
->flags
& WORKER_NOT_RUNNING
))
936 atomic_inc(&pool
->nr_running
);
940 * find_worker_executing_work - find worker which is executing a work
941 * @pool: pool of interest
942 * @work: work to find worker for
944 * Find a worker which is executing @work on @pool by searching
945 * @pool->busy_hash which is keyed by the address of @work. For a worker
946 * to match, its current execution should match the address of @work and
947 * its work function. This is to avoid unwanted dependency between
948 * unrelated work executions through a work item being recycled while still
951 * This is a bit tricky. A work item may be freed once its execution
952 * starts and nothing prevents the freed area from being recycled for
953 * another work item. If the same work item address ends up being reused
954 * before the original execution finishes, workqueue will identify the
955 * recycled work item as currently executing and make it wait until the
956 * current execution finishes, introducing an unwanted dependency.
958 * This function checks the work item address and work function to avoid
959 * false positives. Note that this isn't complete as one may construct a
960 * work function which can introduce dependency onto itself through a
961 * recycled work item. Well, if somebody wants to shoot oneself in the
962 * foot that badly, there's only so much we can do, and if such deadlock
963 * actually occurs, it should be easy to locate the culprit work function.
966 * spin_lock_irq(pool->lock).
969 * Pointer to worker which is executing @work if found, NULL
972 static struct worker
*find_worker_executing_work(struct worker_pool
*pool
,
973 struct work_struct
*work
)
975 struct worker
*worker
;
977 hash_for_each_possible(pool
->busy_hash
, worker
, hentry
,
979 if (worker
->current_work
== work
&&
980 worker
->current_func
== work
->func
)
987 * move_linked_works - move linked works to a list
988 * @work: start of series of works to be scheduled
989 * @head: target list to append @work to
990 * @nextp: out paramter for nested worklist walking
992 * Schedule linked works starting from @work to @head. Work series to
993 * be scheduled starts at @work and includes any consecutive work with
994 * WORK_STRUCT_LINKED set in its predecessor.
996 * If @nextp is not NULL, it's updated to point to the next work of
997 * the last scheduled work. This allows move_linked_works() to be
998 * nested inside outer list_for_each_entry_safe().
1001 * spin_lock_irq(pool->lock).
1003 static void move_linked_works(struct work_struct
*work
, struct list_head
*head
,
1004 struct work_struct
**nextp
)
1006 struct work_struct
*n
;
1009 * Linked worklist will always end before the end of the list,
1010 * use NULL for list head.
1012 list_for_each_entry_safe_from(work
, n
, NULL
, entry
) {
1013 list_move_tail(&work
->entry
, head
);
1014 if (!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))
1019 * If we're already inside safe list traversal and have moved
1020 * multiple works to the scheduled queue, the next position
1021 * needs to be updated.
1028 * get_pwq - get an extra reference on the specified pool_workqueue
1029 * @pwq: pool_workqueue to get
1031 * Obtain an extra reference on @pwq. The caller should guarantee that
1032 * @pwq has positive refcnt and be holding the matching pool->lock.
1034 static void get_pwq(struct pool_workqueue
*pwq
)
1036 lockdep_assert_held(&pwq
->pool
->lock
);
1037 WARN_ON_ONCE(pwq
->refcnt
<= 0);
1042 * put_pwq - put a pool_workqueue reference
1043 * @pwq: pool_workqueue to put
1045 * Drop a reference of @pwq. If its refcnt reaches zero, schedule its
1046 * destruction. The caller should be holding the matching pool->lock.
1048 static void put_pwq(struct pool_workqueue
*pwq
)
1050 lockdep_assert_held(&pwq
->pool
->lock
);
1051 if (likely(--pwq
->refcnt
))
1053 if (WARN_ON_ONCE(!(pwq
->wq
->flags
& WQ_UNBOUND
)))
1056 * @pwq can't be released under pool->lock, bounce to
1057 * pwq_unbound_release_workfn(). This never recurses on the same
1058 * pool->lock as this path is taken only for unbound workqueues and
1059 * the release work item is scheduled on a per-cpu workqueue. To
1060 * avoid lockdep warning, unbound pool->locks are given lockdep
1061 * subclass of 1 in get_unbound_pool().
1063 schedule_work(&pwq
->unbound_release_work
);
1067 * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock
1068 * @pwq: pool_workqueue to put (can be %NULL)
1070 * put_pwq() with locking. This function also allows %NULL @pwq.
1072 static void put_pwq_unlocked(struct pool_workqueue
*pwq
)
1076 * As both pwqs and pools are sched-RCU protected, the
1077 * following lock operations are safe.
1079 spin_lock_irq(&pwq
->pool
->lock
);
1081 spin_unlock_irq(&pwq
->pool
->lock
);
1085 static void pwq_activate_delayed_work(struct work_struct
*work
)
1087 struct pool_workqueue
*pwq
= get_work_pwq(work
);
1089 trace_workqueue_activate_work(work
);
1090 move_linked_works(work
, &pwq
->pool
->worklist
, NULL
);
1091 __clear_bit(WORK_STRUCT_DELAYED_BIT
, work_data_bits(work
));
1095 static void pwq_activate_first_delayed(struct pool_workqueue
*pwq
)
1097 struct work_struct
*work
= list_first_entry(&pwq
->delayed_works
,
1098 struct work_struct
, entry
);
1100 pwq_activate_delayed_work(work
);
1104 * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight
1105 * @pwq: pwq of interest
1106 * @color: color of work which left the queue
1108 * A work either has completed or is removed from pending queue,
1109 * decrement nr_in_flight of its pwq and handle workqueue flushing.
1112 * spin_lock_irq(pool->lock).
1114 static void pwq_dec_nr_in_flight(struct pool_workqueue
*pwq
, int color
)
1116 /* uncolored work items don't participate in flushing or nr_active */
1117 if (color
== WORK_NO_COLOR
)
1120 pwq
->nr_in_flight
[color
]--;
1123 if (!list_empty(&pwq
->delayed_works
)) {
1124 /* one down, submit a delayed one */
1125 if (pwq
->nr_active
< pwq
->max_active
)
1126 pwq_activate_first_delayed(pwq
);
1129 /* is flush in progress and are we at the flushing tip? */
1130 if (likely(pwq
->flush_color
!= color
))
1133 /* are there still in-flight works? */
1134 if (pwq
->nr_in_flight
[color
])
1137 /* this pwq is done, clear flush_color */
1138 pwq
->flush_color
= -1;
1141 * If this was the last pwq, wake up the first flusher. It
1142 * will handle the rest.
1144 if (atomic_dec_and_test(&pwq
->wq
->nr_pwqs_to_flush
))
1145 complete(&pwq
->wq
->first_flusher
->done
);
1151 * try_to_grab_pending - steal work item from worklist and disable irq
1152 * @work: work item to steal
1153 * @is_dwork: @work is a delayed_work
1154 * @flags: place to store irq state
1156 * Try to grab PENDING bit of @work. This function can handle @work in any
1157 * stable state - idle, on timer or on worklist. Return values are
1159 * 1 if @work was pending and we successfully stole PENDING
1160 * 0 if @work was idle and we claimed PENDING
1161 * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry
1162 * -ENOENT if someone else is canceling @work, this state may persist
1163 * for arbitrarily long
1165 * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting
1166 * interrupted while holding PENDING and @work off queue, irq must be
1167 * disabled on entry. This, combined with delayed_work->timer being
1168 * irqsafe, ensures that we return -EAGAIN for finite short period of time.
1170 * On successful return, >= 0, irq is disabled and the caller is
1171 * responsible for releasing it using local_irq_restore(*@flags).
1173 * This function is safe to call from any context including IRQ handler.
1175 static int try_to_grab_pending(struct work_struct
*work
, bool is_dwork
,
1176 unsigned long *flags
)
1178 struct worker_pool
*pool
;
1179 struct pool_workqueue
*pwq
;
1181 local_irq_save(*flags
);
1183 /* try to steal the timer if it exists */
1185 struct delayed_work
*dwork
= to_delayed_work(work
);
1188 * dwork->timer is irqsafe. If del_timer() fails, it's
1189 * guaranteed that the timer is not queued anywhere and not
1190 * running on the local CPU.
1192 if (likely(del_timer(&dwork
->timer
)))
1196 /* try to claim PENDING the normal way */
1197 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
)))
1201 * The queueing is in progress, or it is already queued. Try to
1202 * steal it from ->worklist without clearing WORK_STRUCT_PENDING.
1204 pool
= get_work_pool(work
);
1208 spin_lock(&pool
->lock
);
1210 * work->data is guaranteed to point to pwq only while the work
1211 * item is queued on pwq->wq, and both updating work->data to point
1212 * to pwq on queueing and to pool on dequeueing are done under
1213 * pwq->pool->lock. This in turn guarantees that, if work->data
1214 * points to pwq which is associated with a locked pool, the work
1215 * item is currently queued on that pool.
1217 pwq
= get_work_pwq(work
);
1218 if (pwq
&& pwq
->pool
== pool
) {
1219 debug_work_deactivate(work
);
1222 * A delayed work item cannot be grabbed directly because
1223 * it might have linked NO_COLOR work items which, if left
1224 * on the delayed_list, will confuse pwq->nr_active
1225 * management later on and cause stall. Make sure the work
1226 * item is activated before grabbing.
1228 if (*work_data_bits(work
) & WORK_STRUCT_DELAYED
)
1229 pwq_activate_delayed_work(work
);
1231 list_del_init(&work
->entry
);
1232 pwq_dec_nr_in_flight(get_work_pwq(work
), get_work_color(work
));
1234 /* work->data points to pwq iff queued, point to pool */
1235 set_work_pool_and_keep_pending(work
, pool
->id
);
1237 spin_unlock(&pool
->lock
);
1240 spin_unlock(&pool
->lock
);
1242 local_irq_restore(*flags
);
1243 if (work_is_canceling(work
))
1250 * insert_work - insert a work into a pool
1251 * @pwq: pwq @work belongs to
1252 * @work: work to insert
1253 * @head: insertion point
1254 * @extra_flags: extra WORK_STRUCT_* flags to set
1256 * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to
1257 * work_struct flags.
1260 * spin_lock_irq(pool->lock).
1262 static void insert_work(struct pool_workqueue
*pwq
, struct work_struct
*work
,
1263 struct list_head
*head
, unsigned int extra_flags
)
1265 struct worker_pool
*pool
= pwq
->pool
;
1267 /* we own @work, set data and link */
1268 set_work_pwq(work
, pwq
, extra_flags
);
1269 list_add_tail(&work
->entry
, head
);
1273 * Ensure either wq_worker_sleeping() sees the above
1274 * list_add_tail() or we see zero nr_running to avoid workers lying
1275 * around lazily while there are works to be processed.
1279 if (__need_more_worker(pool
))
1280 wake_up_worker(pool
);
1284 * Test whether @work is being queued from another work executing on the
1287 static bool is_chained_work(struct workqueue_struct
*wq
)
1289 struct worker
*worker
;
1291 worker
= current_wq_worker();
1293 * Return %true iff I'm a worker execuing a work item on @wq. If
1294 * I'm @worker, it's safe to dereference it without locking.
1296 return worker
&& worker
->current_pwq
->wq
== wq
;
1299 static void __queue_work(int cpu
, struct workqueue_struct
*wq
,
1300 struct work_struct
*work
)
1302 struct pool_workqueue
*pwq
;
1303 struct worker_pool
*last_pool
;
1304 struct list_head
*worklist
;
1305 unsigned int work_flags
;
1306 unsigned int req_cpu
= cpu
;
1309 * While a work item is PENDING && off queue, a task trying to
1310 * steal the PENDING will busy-loop waiting for it to either get
1311 * queued or lose PENDING. Grabbing PENDING and queueing should
1312 * happen with IRQ disabled.
1314 WARN_ON_ONCE(!irqs_disabled());
1316 debug_work_activate(work
);
1318 /* if dying, only works from the same workqueue are allowed */
1319 if (unlikely(wq
->flags
& __WQ_DRAINING
) &&
1320 WARN_ON_ONCE(!is_chained_work(wq
)))
1323 if (req_cpu
== WORK_CPU_UNBOUND
)
1324 cpu
= raw_smp_processor_id();
1326 /* pwq which will be used unless @work is executing elsewhere */
1327 if (!(wq
->flags
& WQ_UNBOUND
))
1328 pwq
= per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
1330 pwq
= unbound_pwq_by_node(wq
, cpu_to_node(cpu
));
1333 * If @work was previously on a different pool, it might still be
1334 * running there, in which case the work needs to be queued on that
1335 * pool to guarantee non-reentrancy.
1337 last_pool
= get_work_pool(work
);
1338 if (last_pool
&& last_pool
!= pwq
->pool
) {
1339 struct worker
*worker
;
1341 spin_lock(&last_pool
->lock
);
1343 worker
= find_worker_executing_work(last_pool
, work
);
1345 if (worker
&& worker
->current_pwq
->wq
== wq
) {
1346 pwq
= worker
->current_pwq
;
1348 /* meh... not running there, queue here */
1349 spin_unlock(&last_pool
->lock
);
1350 spin_lock(&pwq
->pool
->lock
);
1353 spin_lock(&pwq
->pool
->lock
);
1357 * pwq is determined and locked. For unbound pools, we could have
1358 * raced with pwq release and it could already be dead. If its
1359 * refcnt is zero, repeat pwq selection. Note that pwqs never die
1360 * without another pwq replacing it in the numa_pwq_tbl or while
1361 * work items are executing on it, so the retrying is guaranteed to
1362 * make forward-progress.
1364 if (unlikely(!pwq
->refcnt
)) {
1365 if (wq
->flags
& WQ_UNBOUND
) {
1366 spin_unlock(&pwq
->pool
->lock
);
1371 WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt",
1375 /* pwq determined, queue */
1376 trace_workqueue_queue_work(req_cpu
, pwq
, work
);
1378 if (WARN_ON(!list_empty(&work
->entry
))) {
1379 spin_unlock(&pwq
->pool
->lock
);
1383 pwq
->nr_in_flight
[pwq
->work_color
]++;
1384 work_flags
= work_color_to_flags(pwq
->work_color
);
1386 if (likely(pwq
->nr_active
< pwq
->max_active
)) {
1387 trace_workqueue_activate_work(work
);
1389 worklist
= &pwq
->pool
->worklist
;
1391 work_flags
|= WORK_STRUCT_DELAYED
;
1392 worklist
= &pwq
->delayed_works
;
1395 insert_work(pwq
, work
, worklist
, work_flags
);
1397 spin_unlock(&pwq
->pool
->lock
);
1401 * queue_work_on - queue work on specific cpu
1402 * @cpu: CPU number to execute work on
1403 * @wq: workqueue to use
1404 * @work: work to queue
1406 * Returns %false if @work was already on a queue, %true otherwise.
1408 * We queue the work to a specific CPU, the caller must ensure it
1411 bool queue_work_on(int cpu
, struct workqueue_struct
*wq
,
1412 struct work_struct
*work
)
1415 unsigned long flags
;
1417 local_irq_save(flags
);
1419 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1420 __queue_work(cpu
, wq
, work
);
1424 local_irq_restore(flags
);
1427 EXPORT_SYMBOL(queue_work_on
);
1429 void delayed_work_timer_fn(unsigned long __data
)
1431 struct delayed_work
*dwork
= (struct delayed_work
*)__data
;
1433 /* should have been called from irqsafe timer with irq already off */
1434 __queue_work(dwork
->cpu
, dwork
->wq
, &dwork
->work
);
1436 EXPORT_SYMBOL(delayed_work_timer_fn
);
1438 static void __queue_delayed_work(int cpu
, struct workqueue_struct
*wq
,
1439 struct delayed_work
*dwork
, unsigned long delay
)
1441 struct timer_list
*timer
= &dwork
->timer
;
1442 struct work_struct
*work
= &dwork
->work
;
1444 WARN_ON_ONCE(timer
->function
!= delayed_work_timer_fn
||
1445 timer
->data
!= (unsigned long)dwork
);
1446 WARN_ON_ONCE(timer_pending(timer
));
1447 WARN_ON_ONCE(!list_empty(&work
->entry
));
1450 * If @delay is 0, queue @dwork->work immediately. This is for
1451 * both optimization and correctness. The earliest @timer can
1452 * expire is on the closest next tick and delayed_work users depend
1453 * on that there's no such delay when @delay is 0.
1456 __queue_work(cpu
, wq
, &dwork
->work
);
1460 timer_stats_timer_set_start_info(&dwork
->timer
);
1464 timer
->expires
= jiffies
+ delay
;
1466 if (unlikely(cpu
!= WORK_CPU_UNBOUND
))
1467 add_timer_on(timer
, cpu
);
1473 * queue_delayed_work_on - queue work on specific CPU after delay
1474 * @cpu: CPU number to execute work on
1475 * @wq: workqueue to use
1476 * @dwork: work to queue
1477 * @delay: number of jiffies to wait before queueing
1479 * Returns %false if @work was already on a queue, %true otherwise. If
1480 * @delay is zero and @dwork is idle, it will be scheduled for immediate
1483 bool queue_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1484 struct delayed_work
*dwork
, unsigned long delay
)
1486 struct work_struct
*work
= &dwork
->work
;
1488 unsigned long flags
;
1490 /* read the comment in __queue_work() */
1491 local_irq_save(flags
);
1493 if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(work
))) {
1494 __queue_delayed_work(cpu
, wq
, dwork
, delay
);
1498 local_irq_restore(flags
);
1501 EXPORT_SYMBOL(queue_delayed_work_on
);
1504 * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU
1505 * @cpu: CPU number to execute work on
1506 * @wq: workqueue to use
1507 * @dwork: work to queue
1508 * @delay: number of jiffies to wait before queueing
1510 * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise,
1511 * modify @dwork's timer so that it expires after @delay. If @delay is
1512 * zero, @work is guaranteed to be scheduled immediately regardless of its
1515 * Returns %false if @dwork was idle and queued, %true if @dwork was
1516 * pending and its timer was modified.
1518 * This function is safe to call from any context including IRQ handler.
1519 * See try_to_grab_pending() for details.
1521 bool mod_delayed_work_on(int cpu
, struct workqueue_struct
*wq
,
1522 struct delayed_work
*dwork
, unsigned long delay
)
1524 unsigned long flags
;
1528 ret
= try_to_grab_pending(&dwork
->work
, true, &flags
);
1529 } while (unlikely(ret
== -EAGAIN
));
1531 if (likely(ret
>= 0)) {
1532 __queue_delayed_work(cpu
, wq
, dwork
, delay
);
1533 local_irq_restore(flags
);
1536 /* -ENOENT from try_to_grab_pending() becomes %true */
1539 EXPORT_SYMBOL_GPL(mod_delayed_work_on
);
1542 * worker_enter_idle - enter idle state
1543 * @worker: worker which is entering idle state
1545 * @worker is entering idle state. Update stats and idle timer if
1549 * spin_lock_irq(pool->lock).
1551 static void worker_enter_idle(struct worker
*worker
)
1553 struct worker_pool
*pool
= worker
->pool
;
1555 if (WARN_ON_ONCE(worker
->flags
& WORKER_IDLE
) ||
1556 WARN_ON_ONCE(!list_empty(&worker
->entry
) &&
1557 (worker
->hentry
.next
|| worker
->hentry
.pprev
)))
1560 /* can't use worker_set_flags(), also called from start_worker() */
1561 worker
->flags
|= WORKER_IDLE
;
1563 worker
->last_active
= jiffies
;
1565 /* idle_list is LIFO */
1566 list_add(&worker
->entry
, &pool
->idle_list
);
1568 if (too_many_workers(pool
) && !timer_pending(&pool
->idle_timer
))
1569 mod_timer(&pool
->idle_timer
, jiffies
+ IDLE_WORKER_TIMEOUT
);
1572 * Sanity check nr_running. Because wq_unbind_fn() releases
1573 * pool->lock between setting %WORKER_UNBOUND and zapping
1574 * nr_running, the warning may trigger spuriously. Check iff
1575 * unbind is not in progress.
1577 WARN_ON_ONCE(!(pool
->flags
& POOL_DISASSOCIATED
) &&
1578 pool
->nr_workers
== pool
->nr_idle
&&
1579 atomic_read(&pool
->nr_running
));
1583 * worker_leave_idle - leave idle state
1584 * @worker: worker which is leaving idle state
1586 * @worker is leaving idle state. Update stats.
1589 * spin_lock_irq(pool->lock).
1591 static void worker_leave_idle(struct worker
*worker
)
1593 struct worker_pool
*pool
= worker
->pool
;
1595 if (WARN_ON_ONCE(!(worker
->flags
& WORKER_IDLE
)))
1597 worker_clr_flags(worker
, WORKER_IDLE
);
1599 list_del_init(&worker
->entry
);
1603 * worker_maybe_bind_and_lock - try to bind %current to worker_pool and lock it
1604 * @pool: target worker_pool
1606 * Bind %current to the cpu of @pool if it is associated and lock @pool.
1608 * Works which are scheduled while the cpu is online must at least be
1609 * scheduled to a worker which is bound to the cpu so that if they are
1610 * flushed from cpu callbacks while cpu is going down, they are
1611 * guaranteed to execute on the cpu.
1613 * This function is to be used by unbound workers and rescuers to bind
1614 * themselves to the target cpu and may race with cpu going down or
1615 * coming online. kthread_bind() can't be used because it may put the
1616 * worker to already dead cpu and set_cpus_allowed_ptr() can't be used
1617 * verbatim as it's best effort and blocking and pool may be
1618 * [dis]associated in the meantime.
1620 * This function tries set_cpus_allowed() and locks pool and verifies the
1621 * binding against %POOL_DISASSOCIATED which is set during
1622 * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker
1623 * enters idle state or fetches works without dropping lock, it can
1624 * guarantee the scheduling requirement described in the first paragraph.
1627 * Might sleep. Called without any lock but returns with pool->lock
1631 * %true if the associated pool is online (@worker is successfully
1632 * bound), %false if offline.
1634 static bool worker_maybe_bind_and_lock(struct worker_pool
*pool
)
1635 __acquires(&pool
->lock
)
1639 * The following call may fail, succeed or succeed
1640 * without actually migrating the task to the cpu if
1641 * it races with cpu hotunplug operation. Verify
1642 * against POOL_DISASSOCIATED.
1644 if (!(pool
->flags
& POOL_DISASSOCIATED
))
1645 set_cpus_allowed_ptr(current
, pool
->attrs
->cpumask
);
1647 spin_lock_irq(&pool
->lock
);
1648 if (pool
->flags
& POOL_DISASSOCIATED
)
1650 if (task_cpu(current
) == pool
->cpu
&&
1651 cpumask_equal(¤t
->cpus_allowed
, pool
->attrs
->cpumask
))
1653 spin_unlock_irq(&pool
->lock
);
1656 * We've raced with CPU hot[un]plug. Give it a breather
1657 * and retry migration. cond_resched() is required here;
1658 * otherwise, we might deadlock against cpu_stop trying to
1659 * bring down the CPU on non-preemptive kernel.
1666 static struct worker
*alloc_worker(void)
1668 struct worker
*worker
;
1670 worker
= kzalloc(sizeof(*worker
), GFP_KERNEL
);
1672 INIT_LIST_HEAD(&worker
->entry
);
1673 INIT_LIST_HEAD(&worker
->scheduled
);
1674 /* on creation a worker is in !idle && prep state */
1675 worker
->flags
= WORKER_PREP
;
1681 * create_worker - create a new workqueue worker
1682 * @pool: pool the new worker will belong to
1684 * Create a new worker which is bound to @pool. The returned worker
1685 * can be started by calling start_worker() or destroyed using
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 lockdep_assert_held(&pool
->manager_mutex
);
1703 * ID is needed to determine kthread name. Allocate ID first
1704 * without installing the pointer.
1706 idr_preload(GFP_KERNEL
);
1707 spin_lock_irq(&pool
->lock
);
1709 id
= idr_alloc(&pool
->worker_idr
, NULL
, 0, 0, GFP_NOWAIT
);
1711 spin_unlock_irq(&pool
->lock
);
1716 worker
= alloc_worker();
1720 worker
->pool
= pool
;
1724 snprintf(id_buf
, sizeof(id_buf
), "%d:%d%s", pool
->cpu
, id
,
1725 pool
->attrs
->nice
< 0 ? "H" : "");
1727 snprintf(id_buf
, sizeof(id_buf
), "u%d:%d", pool
->id
, id
);
1729 worker
->task
= kthread_create_on_node(worker_thread
, worker
, pool
->node
,
1730 "kworker/%s", id_buf
);
1731 if (IS_ERR(worker
->task
))
1735 * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any
1736 * online CPUs. It'll be re-applied when any of the CPUs come up.
1738 set_user_nice(worker
->task
, pool
->attrs
->nice
);
1739 set_cpus_allowed_ptr(worker
->task
, pool
->attrs
->cpumask
);
1741 /* prevent userland from meddling with cpumask of workqueue workers */
1742 worker
->task
->flags
|= PF_NO_SETAFFINITY
;
1745 * The caller is responsible for ensuring %POOL_DISASSOCIATED
1746 * remains stable across this function. See the comments above the
1747 * flag definition for details.
1749 if (pool
->flags
& POOL_DISASSOCIATED
)
1750 worker
->flags
|= WORKER_UNBOUND
;
1752 /* successful, commit the pointer to idr */
1753 spin_lock_irq(&pool
->lock
);
1754 idr_replace(&pool
->worker_idr
, worker
, worker
->id
);
1755 spin_unlock_irq(&pool
->lock
);
1761 spin_lock_irq(&pool
->lock
);
1762 idr_remove(&pool
->worker_idr
, id
);
1763 spin_unlock_irq(&pool
->lock
);
1770 * start_worker - start a newly created worker
1771 * @worker: worker to start
1773 * Make the pool aware of @worker and start it.
1776 * spin_lock_irq(pool->lock).
1778 static void start_worker(struct worker
*worker
)
1780 worker
->flags
|= WORKER_STARTED
;
1781 worker
->pool
->nr_workers
++;
1782 worker_enter_idle(worker
);
1783 wake_up_process(worker
->task
);
1787 * create_and_start_worker - create and start a worker for a pool
1788 * @pool: the target pool
1790 * Grab the managership of @pool and create and start a new worker for it.
1792 static int create_and_start_worker(struct worker_pool
*pool
)
1794 struct worker
*worker
;
1796 mutex_lock(&pool
->manager_mutex
);
1798 worker
= create_worker(pool
);
1800 spin_lock_irq(&pool
->lock
);
1801 start_worker(worker
);
1802 spin_unlock_irq(&pool
->lock
);
1805 mutex_unlock(&pool
->manager_mutex
);
1807 return worker
? 0 : -ENOMEM
;
1811 * destroy_worker - destroy a workqueue worker
1812 * @worker: worker to be destroyed
1814 * Destroy @worker and adjust @pool stats accordingly.
1817 * spin_lock_irq(pool->lock) which is released and regrabbed.
1819 static void destroy_worker(struct worker
*worker
)
1821 struct worker_pool
*pool
= worker
->pool
;
1823 lockdep_assert_held(&pool
->manager_mutex
);
1824 lockdep_assert_held(&pool
->lock
);
1826 /* sanity check frenzy */
1827 if (WARN_ON(worker
->current_work
) ||
1828 WARN_ON(!list_empty(&worker
->scheduled
)))
1831 if (worker
->flags
& WORKER_STARTED
)
1833 if (worker
->flags
& WORKER_IDLE
)
1836 list_del_init(&worker
->entry
);
1837 worker
->flags
|= WORKER_DIE
;
1839 idr_remove(&pool
->worker_idr
, worker
->id
);
1841 spin_unlock_irq(&pool
->lock
);
1843 kthread_stop(worker
->task
);
1846 spin_lock_irq(&pool
->lock
);
1849 static void idle_worker_timeout(unsigned long __pool
)
1851 struct worker_pool
*pool
= (void *)__pool
;
1853 spin_lock_irq(&pool
->lock
);
1855 if (too_many_workers(pool
)) {
1856 struct worker
*worker
;
1857 unsigned long expires
;
1859 /* idle_list is kept in LIFO order, check the last one */
1860 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
1861 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
1863 if (time_before(jiffies
, expires
))
1864 mod_timer(&pool
->idle_timer
, expires
);
1866 /* it's been idle for too long, wake up manager */
1867 pool
->flags
|= POOL_MANAGE_WORKERS
;
1868 wake_up_worker(pool
);
1872 spin_unlock_irq(&pool
->lock
);
1875 static void send_mayday(struct work_struct
*work
)
1877 struct pool_workqueue
*pwq
= get_work_pwq(work
);
1878 struct workqueue_struct
*wq
= pwq
->wq
;
1880 lockdep_assert_held(&wq_mayday_lock
);
1885 /* mayday mayday mayday */
1886 if (list_empty(&pwq
->mayday_node
)) {
1887 list_add_tail(&pwq
->mayday_node
, &wq
->maydays
);
1888 wake_up_process(wq
->rescuer
->task
);
1892 static void pool_mayday_timeout(unsigned long __pool
)
1894 struct worker_pool
*pool
= (void *)__pool
;
1895 struct work_struct
*work
;
1897 spin_lock_irq(&wq_mayday_lock
); /* for wq->maydays */
1898 spin_lock(&pool
->lock
);
1900 if (need_to_create_worker(pool
)) {
1902 * We've been trying to create a new worker but
1903 * haven't been successful. We might be hitting an
1904 * allocation deadlock. Send distress signals to
1907 list_for_each_entry(work
, &pool
->worklist
, entry
)
1911 spin_unlock(&pool
->lock
);
1912 spin_unlock_irq(&wq_mayday_lock
);
1914 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INTERVAL
);
1918 * maybe_create_worker - create a new worker if necessary
1919 * @pool: pool to create a new worker for
1921 * Create a new worker for @pool if necessary. @pool is guaranteed to
1922 * have at least one idle worker on return from this function. If
1923 * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is
1924 * sent to all rescuers with works scheduled on @pool to resolve
1925 * possible allocation deadlock.
1927 * On return, need_to_create_worker() is guaranteed to be %false and
1928 * may_start_working() %true.
1931 * spin_lock_irq(pool->lock) which may be released and regrabbed
1932 * multiple times. Does GFP_KERNEL allocations. Called only from
1936 * %false if no action was taken and pool->lock stayed locked, %true
1939 static bool maybe_create_worker(struct worker_pool
*pool
)
1940 __releases(&pool
->lock
)
1941 __acquires(&pool
->lock
)
1943 if (!need_to_create_worker(pool
))
1946 spin_unlock_irq(&pool
->lock
);
1948 /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */
1949 mod_timer(&pool
->mayday_timer
, jiffies
+ MAYDAY_INITIAL_TIMEOUT
);
1952 struct worker
*worker
;
1954 worker
= create_worker(pool
);
1956 del_timer_sync(&pool
->mayday_timer
);
1957 spin_lock_irq(&pool
->lock
);
1958 start_worker(worker
);
1959 if (WARN_ON_ONCE(need_to_create_worker(pool
)))
1964 if (!need_to_create_worker(pool
))
1967 __set_current_state(TASK_INTERRUPTIBLE
);
1968 schedule_timeout(CREATE_COOLDOWN
);
1970 if (!need_to_create_worker(pool
))
1974 del_timer_sync(&pool
->mayday_timer
);
1975 spin_lock_irq(&pool
->lock
);
1976 if (need_to_create_worker(pool
))
1982 * maybe_destroy_worker - destroy workers which have been idle for a while
1983 * @pool: pool to destroy workers for
1985 * Destroy @pool workers which have been idle for longer than
1986 * IDLE_WORKER_TIMEOUT.
1989 * spin_lock_irq(pool->lock) which may be released and regrabbed
1990 * multiple times. Called only from manager.
1993 * %false if no action was taken and pool->lock stayed locked, %true
1996 static bool maybe_destroy_workers(struct worker_pool
*pool
)
2000 while (too_many_workers(pool
)) {
2001 struct worker
*worker
;
2002 unsigned long expires
;
2004 worker
= list_entry(pool
->idle_list
.prev
, struct worker
, entry
);
2005 expires
= worker
->last_active
+ IDLE_WORKER_TIMEOUT
;
2007 if (time_before(jiffies
, expires
)) {
2008 mod_timer(&pool
->idle_timer
, expires
);
2012 destroy_worker(worker
);
2020 * manage_workers - manage worker pool
2023 * Assume the manager role and manage the worker pool @worker belongs
2024 * to. At any given time, there can be only zero or one manager per
2025 * pool. The exclusion is handled automatically by this function.
2027 * The caller can safely start processing works on false return. On
2028 * true return, it's guaranteed that need_to_create_worker() is false
2029 * and may_start_working() is true.
2032 * spin_lock_irq(pool->lock) which may be released and regrabbed
2033 * multiple times. Does GFP_KERNEL allocations.
2036 * spin_lock_irq(pool->lock) which may be released and regrabbed
2037 * multiple times. Does GFP_KERNEL allocations.
2039 static bool manage_workers(struct worker
*worker
)
2041 struct worker_pool
*pool
= worker
->pool
;
2045 * Managership is governed by two mutexes - manager_arb and
2046 * manager_mutex. manager_arb handles arbitration of manager role.
2047 * Anyone who successfully grabs manager_arb wins the arbitration
2048 * and becomes the manager. mutex_trylock() on pool->manager_arb
2049 * failure while holding pool->lock reliably indicates that someone
2050 * else is managing the pool and the worker which failed trylock
2051 * can proceed to executing work items. This means that anyone
2052 * grabbing manager_arb is responsible for actually performing
2053 * manager duties. If manager_arb is grabbed and released without
2054 * actual management, the pool may stall indefinitely.
2056 * manager_mutex is used for exclusion of actual management
2057 * operations. The holder of manager_mutex can be sure that none
2058 * of management operations, including creation and destruction of
2059 * workers, won't take place until the mutex is released. Because
2060 * manager_mutex doesn't interfere with manager role arbitration,
2061 * it is guaranteed that the pool's management, while may be
2062 * delayed, won't be disturbed by someone else grabbing
2065 if (!mutex_trylock(&pool
->manager_arb
))
2069 * With manager arbitration won, manager_mutex would be free in
2070 * most cases. trylock first without dropping @pool->lock.
2072 if (unlikely(!mutex_trylock(&pool
->manager_mutex
))) {
2073 spin_unlock_irq(&pool
->lock
);
2074 mutex_lock(&pool
->manager_mutex
);
2075 spin_lock_irq(&pool
->lock
);
2079 pool
->flags
&= ~POOL_MANAGE_WORKERS
;
2082 * Destroy and then create so that may_start_working() is true
2085 ret
|= maybe_destroy_workers(pool
);
2086 ret
|= maybe_create_worker(pool
);
2088 mutex_unlock(&pool
->manager_mutex
);
2089 mutex_unlock(&pool
->manager_arb
);
2094 * process_one_work - process single work
2096 * @work: work to process
2098 * Process @work. This function contains all the logics necessary to
2099 * process a single work including synchronization against and
2100 * interaction with other workers on the same cpu, queueing and
2101 * flushing. As long as context requirement is met, any worker can
2102 * call this function to process a work.
2105 * spin_lock_irq(pool->lock) which is released and regrabbed.
2107 static void process_one_work(struct worker
*worker
, struct work_struct
*work
)
2108 __releases(&pool
->lock
)
2109 __acquires(&pool
->lock
)
2111 struct pool_workqueue
*pwq
= get_work_pwq(work
);
2112 struct worker_pool
*pool
= worker
->pool
;
2113 bool cpu_intensive
= pwq
->wq
->flags
& WQ_CPU_INTENSIVE
;
2115 struct worker
*collision
;
2116 #ifdef CONFIG_LOCKDEP
2118 * It is permissible to free the struct work_struct from
2119 * inside the function that is called from it, this we need to
2120 * take into account for lockdep too. To avoid bogus "held
2121 * lock freed" warnings as well as problems when looking into
2122 * work->lockdep_map, make a copy and use that here.
2124 struct lockdep_map lockdep_map
;
2126 lockdep_copy_map(&lockdep_map
, &work
->lockdep_map
);
2129 * Ensure we're on the correct CPU. DISASSOCIATED test is
2130 * necessary to avoid spurious warnings from rescuers servicing the
2131 * unbound or a disassociated pool.
2133 WARN_ON_ONCE(!(worker
->flags
& WORKER_UNBOUND
) &&
2134 !(pool
->flags
& POOL_DISASSOCIATED
) &&
2135 raw_smp_processor_id() != pool
->cpu
);
2138 * A single work shouldn't be executed concurrently by
2139 * multiple workers on a single cpu. Check whether anyone is
2140 * already processing the work. If so, defer the work to the
2141 * currently executing one.
2143 collision
= find_worker_executing_work(pool
, work
);
2144 if (unlikely(collision
)) {
2145 move_linked_works(work
, &collision
->scheduled
, NULL
);
2149 /* claim and dequeue */
2150 debug_work_deactivate(work
);
2151 hash_add(pool
->busy_hash
, &worker
->hentry
, (unsigned long)work
);
2152 worker
->current_work
= work
;
2153 worker
->current_func
= work
->func
;
2154 worker
->current_pwq
= pwq
;
2155 work_color
= get_work_color(work
);
2157 list_del_init(&work
->entry
);
2160 * CPU intensive works don't participate in concurrency
2161 * management. They're the scheduler's responsibility.
2163 if (unlikely(cpu_intensive
))
2164 worker_set_flags(worker
, WORKER_CPU_INTENSIVE
, true);
2167 * Unbound pool isn't concurrency managed and work items should be
2168 * executed ASAP. Wake up another worker if necessary.
2170 if ((worker
->flags
& WORKER_UNBOUND
) && need_more_worker(pool
))
2171 wake_up_worker(pool
);
2174 * Record the last pool and clear PENDING which should be the last
2175 * update to @work. Also, do this inside @pool->lock so that
2176 * PENDING and queued state changes happen together while IRQ is
2179 set_work_pool_and_clear_pending(work
, pool
->id
);
2181 spin_unlock_irq(&pool
->lock
);
2183 lock_map_acquire_read(&pwq
->wq
->lockdep_map
);
2184 lock_map_acquire(&lockdep_map
);
2185 trace_workqueue_execute_start(work
);
2186 worker
->current_func(work
);
2188 * While we must be careful to not use "work" after this, the trace
2189 * point will only record its address.
2191 trace_workqueue_execute_end(work
);
2192 lock_map_release(&lockdep_map
);
2193 lock_map_release(&pwq
->wq
->lockdep_map
);
2195 if (unlikely(in_atomic() || lockdep_depth(current
) > 0)) {
2196 pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n"
2197 " last function: %pf\n",
2198 current
->comm
, preempt_count(), task_pid_nr(current
),
2199 worker
->current_func
);
2200 debug_show_held_locks(current
);
2205 * The following prevents a kworker from hogging CPU on !PREEMPT
2206 * kernels, where a requeueing work item waiting for something to
2207 * happen could deadlock with stop_machine as such work item could
2208 * indefinitely requeue itself while all other CPUs are trapped in
2213 spin_lock_irq(&pool
->lock
);
2215 /* clear cpu intensive status */
2216 if (unlikely(cpu_intensive
))
2217 worker_clr_flags(worker
, WORKER_CPU_INTENSIVE
);
2219 /* we're done with it, release */
2220 hash_del(&worker
->hentry
);
2221 worker
->current_work
= NULL
;
2222 worker
->current_func
= NULL
;
2223 worker
->current_pwq
= NULL
;
2224 worker
->desc_valid
= false;
2225 pwq_dec_nr_in_flight(pwq
, work_color
);
2229 * process_scheduled_works - process scheduled works
2232 * Process all scheduled works. Please note that the scheduled list
2233 * may change while processing a work, so this function repeatedly
2234 * fetches a work from the top and executes it.
2237 * spin_lock_irq(pool->lock) which may be released and regrabbed
2240 static void process_scheduled_works(struct worker
*worker
)
2242 while (!list_empty(&worker
->scheduled
)) {
2243 struct work_struct
*work
= list_first_entry(&worker
->scheduled
,
2244 struct work_struct
, entry
);
2245 process_one_work(worker
, work
);
2250 * worker_thread - the worker thread function
2253 * The worker thread function. All workers belong to a worker_pool -
2254 * either a per-cpu one or dynamic unbound one. These workers process all
2255 * work items regardless of their specific target workqueue. The only
2256 * exception is work items which belong to workqueues with a rescuer which
2257 * will be explained in rescuer_thread().
2259 static int worker_thread(void *__worker
)
2261 struct worker
*worker
= __worker
;
2262 struct worker_pool
*pool
= worker
->pool
;
2264 /* tell the scheduler that this is a workqueue worker */
2265 worker
->task
->flags
|= PF_WQ_WORKER
;
2267 spin_lock_irq(&pool
->lock
);
2269 /* am I supposed to die? */
2270 if (unlikely(worker
->flags
& WORKER_DIE
)) {
2271 spin_unlock_irq(&pool
->lock
);
2272 WARN_ON_ONCE(!list_empty(&worker
->entry
));
2273 worker
->task
->flags
&= ~PF_WQ_WORKER
;
2277 worker_leave_idle(worker
);
2279 /* no more worker necessary? */
2280 if (!need_more_worker(pool
))
2283 /* do we need to manage? */
2284 if (unlikely(!may_start_working(pool
)) && manage_workers(worker
))
2288 * ->scheduled list can only be filled while a worker is
2289 * preparing to process a work or actually processing it.
2290 * Make sure nobody diddled with it while I was sleeping.
2292 WARN_ON_ONCE(!list_empty(&worker
->scheduled
));
2295 * Finish PREP stage. We're guaranteed to have at least one idle
2296 * worker or that someone else has already assumed the manager
2297 * role. This is where @worker starts participating in concurrency
2298 * management if applicable and concurrency management is restored
2299 * after being rebound. See rebind_workers() for details.
2301 worker_clr_flags(worker
, WORKER_PREP
| WORKER_REBOUND
);
2304 struct work_struct
*work
=
2305 list_first_entry(&pool
->worklist
,
2306 struct work_struct
, entry
);
2308 if (likely(!(*work_data_bits(work
) & WORK_STRUCT_LINKED
))) {
2309 /* optimization path, not strictly necessary */
2310 process_one_work(worker
, work
);
2311 if (unlikely(!list_empty(&worker
->scheduled
)))
2312 process_scheduled_works(worker
);
2314 move_linked_works(work
, &worker
->scheduled
, NULL
);
2315 process_scheduled_works(worker
);
2317 } while (keep_working(pool
));
2319 worker_set_flags(worker
, WORKER_PREP
, false);
2321 if (unlikely(need_to_manage_workers(pool
)) && manage_workers(worker
))
2325 * pool->lock is held and there's no work to process and no need to
2326 * manage, sleep. Workers are woken up only while holding
2327 * pool->lock or from local cpu, so setting the current state
2328 * before releasing pool->lock is enough to prevent losing any
2331 worker_enter_idle(worker
);
2332 __set_current_state(TASK_INTERRUPTIBLE
);
2333 spin_unlock_irq(&pool
->lock
);
2339 * rescuer_thread - the rescuer thread function
2342 * Workqueue rescuer thread function. There's one rescuer for each
2343 * workqueue which has WQ_MEM_RECLAIM set.
2345 * Regular work processing on a pool may block trying to create a new
2346 * worker which uses GFP_KERNEL allocation which has slight chance of
2347 * developing into deadlock if some works currently on the same queue
2348 * need to be processed to satisfy the GFP_KERNEL allocation. This is
2349 * the problem rescuer solves.
2351 * When such condition is possible, the pool summons rescuers of all
2352 * workqueues which have works queued on the pool and let them process
2353 * those works so that forward progress can be guaranteed.
2355 * This should happen rarely.
2357 static int rescuer_thread(void *__rescuer
)
2359 struct worker
*rescuer
= __rescuer
;
2360 struct workqueue_struct
*wq
= rescuer
->rescue_wq
;
2361 struct list_head
*scheduled
= &rescuer
->scheduled
;
2363 set_user_nice(current
, RESCUER_NICE_LEVEL
);
2366 * Mark rescuer as worker too. As WORKER_PREP is never cleared, it
2367 * doesn't participate in concurrency management.
2369 rescuer
->task
->flags
|= PF_WQ_WORKER
;
2371 set_current_state(TASK_INTERRUPTIBLE
);
2373 if (kthread_should_stop()) {
2374 __set_current_state(TASK_RUNNING
);
2375 rescuer
->task
->flags
&= ~PF_WQ_WORKER
;
2379 /* see whether any pwq is asking for help */
2380 spin_lock_irq(&wq_mayday_lock
);
2382 while (!list_empty(&wq
->maydays
)) {
2383 struct pool_workqueue
*pwq
= list_first_entry(&wq
->maydays
,
2384 struct pool_workqueue
, mayday_node
);
2385 struct worker_pool
*pool
= pwq
->pool
;
2386 struct work_struct
*work
, *n
;
2388 __set_current_state(TASK_RUNNING
);
2389 list_del_init(&pwq
->mayday_node
);
2391 spin_unlock_irq(&wq_mayday_lock
);
2393 /* migrate to the target cpu if possible */
2394 worker_maybe_bind_and_lock(pool
);
2395 rescuer
->pool
= pool
;
2398 * Slurp in all works issued via this workqueue and
2401 WARN_ON_ONCE(!list_empty(&rescuer
->scheduled
));
2402 list_for_each_entry_safe(work
, n
, &pool
->worklist
, entry
)
2403 if (get_work_pwq(work
) == pwq
)
2404 move_linked_works(work
, scheduled
, &n
);
2406 process_scheduled_works(rescuer
);
2409 * Leave this pool. If keep_working() is %true, notify a
2410 * regular worker; otherwise, we end up with 0 concurrency
2411 * and stalling the execution.
2413 if (keep_working(pool
))
2414 wake_up_worker(pool
);
2416 rescuer
->pool
= NULL
;
2417 spin_unlock(&pool
->lock
);
2418 spin_lock(&wq_mayday_lock
);
2421 spin_unlock_irq(&wq_mayday_lock
);
2423 /* rescuers should never participate in concurrency management */
2424 WARN_ON_ONCE(!(rescuer
->flags
& WORKER_NOT_RUNNING
));
2430 struct work_struct work
;
2431 struct completion done
;
2434 static void wq_barrier_func(struct work_struct
*work
)
2436 struct wq_barrier
*barr
= container_of(work
, struct wq_barrier
, work
);
2437 complete(&barr
->done
);
2441 * insert_wq_barrier - insert a barrier work
2442 * @pwq: pwq to insert barrier into
2443 * @barr: wq_barrier to insert
2444 * @target: target work to attach @barr to
2445 * @worker: worker currently executing @target, NULL if @target is not executing
2447 * @barr is linked to @target such that @barr is completed only after
2448 * @target finishes execution. Please note that the ordering
2449 * guarantee is observed only with respect to @target and on the local
2452 * Currently, a queued barrier can't be canceled. This is because
2453 * try_to_grab_pending() can't determine whether the work to be
2454 * grabbed is at the head of the queue and thus can't clear LINKED
2455 * flag of the previous work while there must be a valid next work
2456 * after a work with LINKED flag set.
2458 * Note that when @worker is non-NULL, @target may be modified
2459 * underneath us, so we can't reliably determine pwq from @target.
2462 * spin_lock_irq(pool->lock).
2464 static void insert_wq_barrier(struct pool_workqueue
*pwq
,
2465 struct wq_barrier
*barr
,
2466 struct work_struct
*target
, struct worker
*worker
)
2468 struct list_head
*head
;
2469 unsigned int linked
= 0;
2472 * debugobject calls are safe here even with pool->lock locked
2473 * as we know for sure that this will not trigger any of the
2474 * checks and call back into the fixup functions where we
2477 INIT_WORK_ONSTACK(&barr
->work
, wq_barrier_func
);
2478 __set_bit(WORK_STRUCT_PENDING_BIT
, work_data_bits(&barr
->work
));
2479 init_completion(&barr
->done
);
2482 * If @target is currently being executed, schedule the
2483 * barrier to the worker; otherwise, put it after @target.
2486 head
= worker
->scheduled
.next
;
2488 unsigned long *bits
= work_data_bits(target
);
2490 head
= target
->entry
.next
;
2491 /* there can already be other linked works, inherit and set */
2492 linked
= *bits
& WORK_STRUCT_LINKED
;
2493 __set_bit(WORK_STRUCT_LINKED_BIT
, bits
);
2496 debug_work_activate(&barr
->work
);
2497 insert_work(pwq
, &barr
->work
, head
,
2498 work_color_to_flags(WORK_NO_COLOR
) | linked
);
2502 * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing
2503 * @wq: workqueue being flushed
2504 * @flush_color: new flush color, < 0 for no-op
2505 * @work_color: new work color, < 0 for no-op
2507 * Prepare pwqs for workqueue flushing.
2509 * If @flush_color is non-negative, flush_color on all pwqs should be
2510 * -1. If no pwq has in-flight commands at the specified color, all
2511 * pwq->flush_color's stay at -1 and %false is returned. If any pwq
2512 * has in flight commands, its pwq->flush_color is set to
2513 * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq
2514 * wakeup logic is armed and %true is returned.
2516 * The caller should have initialized @wq->first_flusher prior to
2517 * calling this function with non-negative @flush_color. If
2518 * @flush_color is negative, no flush color update is done and %false
2521 * If @work_color is non-negative, all pwqs should have the same
2522 * work_color which is previous to @work_color and all will be
2523 * advanced to @work_color.
2526 * mutex_lock(wq->mutex).
2529 * %true if @flush_color >= 0 and there's something to flush. %false
2532 static bool flush_workqueue_prep_pwqs(struct workqueue_struct
*wq
,
2533 int flush_color
, int work_color
)
2536 struct pool_workqueue
*pwq
;
2538 if (flush_color
>= 0) {
2539 WARN_ON_ONCE(atomic_read(&wq
->nr_pwqs_to_flush
));
2540 atomic_set(&wq
->nr_pwqs_to_flush
, 1);
2543 for_each_pwq(pwq
, wq
) {
2544 struct worker_pool
*pool
= pwq
->pool
;
2546 spin_lock_irq(&pool
->lock
);
2548 if (flush_color
>= 0) {
2549 WARN_ON_ONCE(pwq
->flush_color
!= -1);
2551 if (pwq
->nr_in_flight
[flush_color
]) {
2552 pwq
->flush_color
= flush_color
;
2553 atomic_inc(&wq
->nr_pwqs_to_flush
);
2558 if (work_color
>= 0) {
2559 WARN_ON_ONCE(work_color
!= work_next_color(pwq
->work_color
));
2560 pwq
->work_color
= work_color
;
2563 spin_unlock_irq(&pool
->lock
);
2566 if (flush_color
>= 0 && atomic_dec_and_test(&wq
->nr_pwqs_to_flush
))
2567 complete(&wq
->first_flusher
->done
);
2573 * flush_workqueue - ensure that any scheduled work has run to completion.
2574 * @wq: workqueue to flush
2576 * This function sleeps until all work items which were queued on entry
2577 * have finished execution, but it is not livelocked by new incoming ones.
2579 void flush_workqueue(struct workqueue_struct
*wq
)
2581 struct wq_flusher this_flusher
= {
2582 .list
= LIST_HEAD_INIT(this_flusher
.list
),
2584 .done
= COMPLETION_INITIALIZER_ONSTACK(this_flusher
.done
),
2588 lock_map_acquire(&wq
->lockdep_map
);
2589 lock_map_release(&wq
->lockdep_map
);
2591 mutex_lock(&wq
->mutex
);
2594 * Start-to-wait phase
2596 next_color
= work_next_color(wq
->work_color
);
2598 if (next_color
!= wq
->flush_color
) {
2600 * Color space is not full. The current work_color
2601 * becomes our flush_color and work_color is advanced
2604 WARN_ON_ONCE(!list_empty(&wq
->flusher_overflow
));
2605 this_flusher
.flush_color
= wq
->work_color
;
2606 wq
->work_color
= next_color
;
2608 if (!wq
->first_flusher
) {
2609 /* no flush in progress, become the first flusher */
2610 WARN_ON_ONCE(wq
->flush_color
!= this_flusher
.flush_color
);
2612 wq
->first_flusher
= &this_flusher
;
2614 if (!flush_workqueue_prep_pwqs(wq
, wq
->flush_color
,
2616 /* nothing to flush, done */
2617 wq
->flush_color
= next_color
;
2618 wq
->first_flusher
= NULL
;
2623 WARN_ON_ONCE(wq
->flush_color
== this_flusher
.flush_color
);
2624 list_add_tail(&this_flusher
.list
, &wq
->flusher_queue
);
2625 flush_workqueue_prep_pwqs(wq
, -1, wq
->work_color
);
2629 * Oops, color space is full, wait on overflow queue.
2630 * The next flush completion will assign us
2631 * flush_color and transfer to flusher_queue.
2633 list_add_tail(&this_flusher
.list
, &wq
->flusher_overflow
);
2636 mutex_unlock(&wq
->mutex
);
2638 wait_for_completion(&this_flusher
.done
);
2641 * Wake-up-and-cascade phase
2643 * First flushers are responsible for cascading flushes and
2644 * handling overflow. Non-first flushers can simply return.
2646 if (wq
->first_flusher
!= &this_flusher
)
2649 mutex_lock(&wq
->mutex
);
2651 /* we might have raced, check again with mutex held */
2652 if (wq
->first_flusher
!= &this_flusher
)
2655 wq
->first_flusher
= NULL
;
2657 WARN_ON_ONCE(!list_empty(&this_flusher
.list
));
2658 WARN_ON_ONCE(wq
->flush_color
!= this_flusher
.flush_color
);
2661 struct wq_flusher
*next
, *tmp
;
2663 /* complete all the flushers sharing the current flush color */
2664 list_for_each_entry_safe(next
, tmp
, &wq
->flusher_queue
, list
) {
2665 if (next
->flush_color
!= wq
->flush_color
)
2667 list_del_init(&next
->list
);
2668 complete(&next
->done
);
2671 WARN_ON_ONCE(!list_empty(&wq
->flusher_overflow
) &&
2672 wq
->flush_color
!= work_next_color(wq
->work_color
));
2674 /* this flush_color is finished, advance by one */
2675 wq
->flush_color
= work_next_color(wq
->flush_color
);
2677 /* one color has been freed, handle overflow queue */
2678 if (!list_empty(&wq
->flusher_overflow
)) {
2680 * Assign the same color to all overflowed
2681 * flushers, advance work_color and append to
2682 * flusher_queue. This is the start-to-wait
2683 * phase for these overflowed flushers.
2685 list_for_each_entry(tmp
, &wq
->flusher_overflow
, list
)
2686 tmp
->flush_color
= wq
->work_color
;
2688 wq
->work_color
= work_next_color(wq
->work_color
);
2690 list_splice_tail_init(&wq
->flusher_overflow
,
2691 &wq
->flusher_queue
);
2692 flush_workqueue_prep_pwqs(wq
, -1, wq
->work_color
);
2695 if (list_empty(&wq
->flusher_queue
)) {
2696 WARN_ON_ONCE(wq
->flush_color
!= wq
->work_color
);
2701 * Need to flush more colors. Make the next flusher
2702 * the new first flusher and arm pwqs.
2704 WARN_ON_ONCE(wq
->flush_color
== wq
->work_color
);
2705 WARN_ON_ONCE(wq
->flush_color
!= next
->flush_color
);
2707 list_del_init(&next
->list
);
2708 wq
->first_flusher
= next
;
2710 if (flush_workqueue_prep_pwqs(wq
, wq
->flush_color
, -1))
2714 * Meh... this color is already done, clear first
2715 * flusher and repeat cascading.
2717 wq
->first_flusher
= NULL
;
2721 mutex_unlock(&wq
->mutex
);
2723 EXPORT_SYMBOL_GPL(flush_workqueue
);
2726 * drain_workqueue - drain a workqueue
2727 * @wq: workqueue to drain
2729 * Wait until the workqueue becomes empty. While draining is in progress,
2730 * only chain queueing is allowed. IOW, only currently pending or running
2731 * work items on @wq can queue further work items on it. @wq is flushed
2732 * repeatedly until it becomes empty. The number of flushing is detemined
2733 * by the depth of chaining and should be relatively short. Whine if it
2736 void drain_workqueue(struct workqueue_struct
*wq
)
2738 unsigned int flush_cnt
= 0;
2739 struct pool_workqueue
*pwq
;
2742 * __queue_work() needs to test whether there are drainers, is much
2743 * hotter than drain_workqueue() and already looks at @wq->flags.
2744 * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers.
2746 mutex_lock(&wq
->mutex
);
2747 if (!wq
->nr_drainers
++)
2748 wq
->flags
|= __WQ_DRAINING
;
2749 mutex_unlock(&wq
->mutex
);
2751 flush_workqueue(wq
);
2753 mutex_lock(&wq
->mutex
);
2755 for_each_pwq(pwq
, wq
) {
2758 spin_lock_irq(&pwq
->pool
->lock
);
2759 drained
= !pwq
->nr_active
&& list_empty(&pwq
->delayed_works
);
2760 spin_unlock_irq(&pwq
->pool
->lock
);
2765 if (++flush_cnt
== 10 ||
2766 (flush_cnt
% 100 == 0 && flush_cnt
<= 1000))
2767 pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n",
2768 wq
->name
, flush_cnt
);
2770 mutex_unlock(&wq
->mutex
);
2774 if (!--wq
->nr_drainers
)
2775 wq
->flags
&= ~__WQ_DRAINING
;
2776 mutex_unlock(&wq
->mutex
);
2778 EXPORT_SYMBOL_GPL(drain_workqueue
);
2780 static bool start_flush_work(struct work_struct
*work
, struct wq_barrier
*barr
)
2782 struct worker
*worker
= NULL
;
2783 struct worker_pool
*pool
;
2784 struct pool_workqueue
*pwq
;
2788 local_irq_disable();
2789 pool
= get_work_pool(work
);
2795 spin_lock(&pool
->lock
);
2796 /* see the comment in try_to_grab_pending() with the same code */
2797 pwq
= get_work_pwq(work
);
2799 if (unlikely(pwq
->pool
!= pool
))
2802 worker
= find_worker_executing_work(pool
, work
);
2805 pwq
= worker
->current_pwq
;
2808 insert_wq_barrier(pwq
, barr
, work
, worker
);
2809 spin_unlock_irq(&pool
->lock
);
2812 * If @max_active is 1 or rescuer is in use, flushing another work
2813 * item on the same workqueue may lead to deadlock. Make sure the
2814 * flusher is not running on the same workqueue by verifying write
2817 if (pwq
->wq
->saved_max_active
== 1 || pwq
->wq
->rescuer
)
2818 lock_map_acquire(&pwq
->wq
->lockdep_map
);
2820 lock_map_acquire_read(&pwq
->wq
->lockdep_map
);
2821 lock_map_release(&pwq
->wq
->lockdep_map
);
2825 spin_unlock_irq(&pool
->lock
);
2829 static bool __flush_work(struct work_struct
*work
)
2831 struct wq_barrier barr
;
2833 if (start_flush_work(work
, &barr
)) {
2834 wait_for_completion(&barr
.done
);
2835 destroy_work_on_stack(&barr
.work
);
2843 * flush_work - wait for a work to finish executing the last queueing instance
2844 * @work: the work to flush
2846 * Wait until @work has finished execution. @work is guaranteed to be idle
2847 * on return if it hasn't been requeued since flush started.
2850 * %true if flush_work() waited for the work to finish execution,
2851 * %false if it was already idle.
2853 bool flush_work(struct work_struct
*work
)
2855 lock_map_acquire(&work
->lockdep_map
);
2856 lock_map_release(&work
->lockdep_map
);
2858 return __flush_work(work
);
2860 EXPORT_SYMBOL_GPL(flush_work
);
2862 static bool __cancel_work_timer(struct work_struct
*work
, bool is_dwork
)
2864 unsigned long flags
;
2868 ret
= try_to_grab_pending(work
, is_dwork
, &flags
);
2870 * If someone else is canceling, wait for the same event it
2871 * would be waiting for before retrying.
2873 if (unlikely(ret
== -ENOENT
))
2875 } while (unlikely(ret
< 0));
2877 /* tell other tasks trying to grab @work to back off */
2878 mark_work_canceling(work
);
2879 local_irq_restore(flags
);
2882 clear_work_data(work
);
2887 * cancel_work_sync - cancel a work and wait for it to finish
2888 * @work: the work to cancel
2890 * Cancel @work and wait for its execution to finish. This function
2891 * can be used even if the work re-queues itself or migrates to
2892 * another workqueue. On return from this function, @work is
2893 * guaranteed to be not pending or executing on any CPU.
2895 * cancel_work_sync(&delayed_work->work) must not be used for
2896 * delayed_work's. Use cancel_delayed_work_sync() instead.
2898 * The caller must ensure that the workqueue on which @work was last
2899 * queued can't be destroyed before this function returns.
2902 * %true if @work was pending, %false otherwise.
2904 bool cancel_work_sync(struct work_struct
*work
)
2906 return __cancel_work_timer(work
, false);
2908 EXPORT_SYMBOL_GPL(cancel_work_sync
);
2911 * flush_delayed_work - wait for a dwork to finish executing the last queueing
2912 * @dwork: the delayed work to flush
2914 * Delayed timer is cancelled and the pending work is queued for
2915 * immediate execution. Like flush_work(), this function only
2916 * considers the last queueing instance of @dwork.
2919 * %true if flush_work() waited for the work to finish execution,
2920 * %false if it was already idle.
2922 bool flush_delayed_work(struct delayed_work
*dwork
)
2924 local_irq_disable();
2925 if (del_timer_sync(&dwork
->timer
))
2926 __queue_work(dwork
->cpu
, dwork
->wq
, &dwork
->work
);
2928 return flush_work(&dwork
->work
);
2930 EXPORT_SYMBOL(flush_delayed_work
);
2933 * cancel_delayed_work - cancel a delayed work
2934 * @dwork: delayed_work to cancel
2936 * Kill off a pending delayed_work. Returns %true if @dwork was pending
2937 * and canceled; %false if wasn't pending. Note that the work callback
2938 * function may still be running on return, unless it returns %true and the
2939 * work doesn't re-arm itself. Explicitly flush or use
2940 * cancel_delayed_work_sync() to wait on it.
2942 * This function is safe to call from any context including IRQ handler.
2944 bool cancel_delayed_work(struct delayed_work
*dwork
)
2946 unsigned long flags
;
2950 ret
= try_to_grab_pending(&dwork
->work
, true, &flags
);
2951 } while (unlikely(ret
== -EAGAIN
));
2953 if (unlikely(ret
< 0))
2956 set_work_pool_and_clear_pending(&dwork
->work
,
2957 get_work_pool_id(&dwork
->work
));
2958 local_irq_restore(flags
);
2961 EXPORT_SYMBOL(cancel_delayed_work
);
2964 * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish
2965 * @dwork: the delayed work cancel
2967 * This is cancel_work_sync() for delayed works.
2970 * %true if @dwork was pending, %false otherwise.
2972 bool cancel_delayed_work_sync(struct delayed_work
*dwork
)
2974 return __cancel_work_timer(&dwork
->work
, true);
2976 EXPORT_SYMBOL(cancel_delayed_work_sync
);
2979 * schedule_on_each_cpu - execute a function synchronously on each online CPU
2980 * @func: the function to call
2982 * schedule_on_each_cpu() executes @func on each online CPU using the
2983 * system workqueue and blocks until all CPUs have completed.
2984 * schedule_on_each_cpu() is very slow.
2987 * 0 on success, -errno on failure.
2989 int schedule_on_each_cpu(work_func_t func
)
2992 struct work_struct __percpu
*works
;
2994 works
= alloc_percpu(struct work_struct
);
3000 for_each_online_cpu(cpu
) {
3001 struct work_struct
*work
= per_cpu_ptr(works
, cpu
);
3003 INIT_WORK(work
, func
);
3004 schedule_work_on(cpu
, work
);
3007 for_each_online_cpu(cpu
)
3008 flush_work(per_cpu_ptr(works
, cpu
));
3016 * flush_scheduled_work - ensure that any scheduled work has run to completion.
3018 * Forces execution of the kernel-global workqueue and blocks until its
3021 * Think twice before calling this function! It's very easy to get into
3022 * trouble if you don't take great care. Either of the following situations
3023 * will lead to deadlock:
3025 * One of the work items currently on the workqueue needs to acquire
3026 * a lock held by your code or its caller.
3028 * Your code is running in the context of a work routine.
3030 * They will be detected by lockdep when they occur, but the first might not
3031 * occur very often. It depends on what work items are on the workqueue and
3032 * what locks they need, which you have no control over.
3034 * In most situations flushing the entire workqueue is overkill; you merely
3035 * need to know that a particular work item isn't queued and isn't running.
3036 * In such cases you should use cancel_delayed_work_sync() or
3037 * cancel_work_sync() instead.
3039 void flush_scheduled_work(void)
3041 flush_workqueue(system_wq
);
3043 EXPORT_SYMBOL(flush_scheduled_work
);
3046 * execute_in_process_context - reliably execute the routine with user context
3047 * @fn: the function to execute
3048 * @ew: guaranteed storage for the execute work structure (must
3049 * be available when the work executes)
3051 * Executes the function immediately if process context is available,
3052 * otherwise schedules the function for delayed execution.
3054 * Returns: 0 - function was executed
3055 * 1 - function was scheduled for execution
3057 int execute_in_process_context(work_func_t fn
, struct execute_work
*ew
)
3059 if (!in_interrupt()) {
3064 INIT_WORK(&ew
->work
, fn
);
3065 schedule_work(&ew
->work
);
3069 EXPORT_SYMBOL_GPL(execute_in_process_context
);
3073 * Workqueues with WQ_SYSFS flag set is visible to userland via
3074 * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the
3075 * following attributes.
3077 * per_cpu RO bool : whether the workqueue is per-cpu or unbound
3078 * max_active RW int : maximum number of in-flight work items
3080 * Unbound workqueues have the following extra attributes.
3082 * id RO int : the associated pool ID
3083 * nice RW int : nice value of the workers
3084 * cpumask RW mask : bitmask of allowed CPUs for the workers
3087 struct workqueue_struct
*wq
;
3091 static struct workqueue_struct
*dev_to_wq(struct device
*dev
)
3093 struct wq_device
*wq_dev
= container_of(dev
, struct wq_device
, dev
);
3098 static ssize_t
wq_per_cpu_show(struct device
*dev
,
3099 struct device_attribute
*attr
, char *buf
)
3101 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3103 return scnprintf(buf
, PAGE_SIZE
, "%d\n", (bool)!(wq
->flags
& WQ_UNBOUND
));
3106 static ssize_t
wq_max_active_show(struct device
*dev
,
3107 struct device_attribute
*attr
, char *buf
)
3109 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3111 return scnprintf(buf
, PAGE_SIZE
, "%d\n", wq
->saved_max_active
);
3114 static ssize_t
wq_max_active_store(struct device
*dev
,
3115 struct device_attribute
*attr
,
3116 const char *buf
, size_t count
)
3118 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3121 if (sscanf(buf
, "%d", &val
) != 1 || val
<= 0)
3124 workqueue_set_max_active(wq
, val
);
3128 static struct device_attribute wq_sysfs_attrs
[] = {
3129 __ATTR(per_cpu
, 0444, wq_per_cpu_show
, NULL
),
3130 __ATTR(max_active
, 0644, wq_max_active_show
, wq_max_active_store
),
3134 static ssize_t
wq_pool_ids_show(struct device
*dev
,
3135 struct device_attribute
*attr
, char *buf
)
3137 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3138 const char *delim
= "";
3139 int node
, written
= 0;
3141 rcu_read_lock_sched();
3142 for_each_node(node
) {
3143 written
+= scnprintf(buf
+ written
, PAGE_SIZE
- written
,
3144 "%s%d:%d", delim
, node
,
3145 unbound_pwq_by_node(wq
, node
)->pool
->id
);
3148 written
+= scnprintf(buf
+ written
, PAGE_SIZE
- written
, "\n");
3149 rcu_read_unlock_sched();
3154 static ssize_t
wq_nice_show(struct device
*dev
, struct device_attribute
*attr
,
3157 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3160 mutex_lock(&wq
->mutex
);
3161 written
= scnprintf(buf
, PAGE_SIZE
, "%d\n", wq
->unbound_attrs
->nice
);
3162 mutex_unlock(&wq
->mutex
);
3167 /* prepare workqueue_attrs for sysfs store operations */
3168 static struct workqueue_attrs
*wq_sysfs_prep_attrs(struct workqueue_struct
*wq
)
3170 struct workqueue_attrs
*attrs
;
3172 attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3176 mutex_lock(&wq
->mutex
);
3177 copy_workqueue_attrs(attrs
, wq
->unbound_attrs
);
3178 mutex_unlock(&wq
->mutex
);
3182 static ssize_t
wq_nice_store(struct device
*dev
, struct device_attribute
*attr
,
3183 const char *buf
, size_t count
)
3185 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3186 struct workqueue_attrs
*attrs
;
3189 attrs
= wq_sysfs_prep_attrs(wq
);
3193 if (sscanf(buf
, "%d", &attrs
->nice
) == 1 &&
3194 attrs
->nice
>= -20 && attrs
->nice
<= 19)
3195 ret
= apply_workqueue_attrs(wq
, attrs
);
3199 free_workqueue_attrs(attrs
);
3200 return ret
?: count
;
3203 static ssize_t
wq_cpumask_show(struct device
*dev
,
3204 struct device_attribute
*attr
, char *buf
)
3206 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3209 mutex_lock(&wq
->mutex
);
3210 written
= cpumask_scnprintf(buf
, PAGE_SIZE
, wq
->unbound_attrs
->cpumask
);
3211 mutex_unlock(&wq
->mutex
);
3213 written
+= scnprintf(buf
+ written
, PAGE_SIZE
- written
, "\n");
3217 static ssize_t
wq_cpumask_store(struct device
*dev
,
3218 struct device_attribute
*attr
,
3219 const char *buf
, size_t count
)
3221 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3222 struct workqueue_attrs
*attrs
;
3225 attrs
= wq_sysfs_prep_attrs(wq
);
3229 ret
= cpumask_parse(buf
, attrs
->cpumask
);
3231 ret
= apply_workqueue_attrs(wq
, attrs
);
3233 free_workqueue_attrs(attrs
);
3234 return ret
?: count
;
3237 static ssize_t
wq_numa_show(struct device
*dev
, struct device_attribute
*attr
,
3240 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3243 mutex_lock(&wq
->mutex
);
3244 written
= scnprintf(buf
, PAGE_SIZE
, "%d\n",
3245 !wq
->unbound_attrs
->no_numa
);
3246 mutex_unlock(&wq
->mutex
);
3251 static ssize_t
wq_numa_store(struct device
*dev
, struct device_attribute
*attr
,
3252 const char *buf
, size_t count
)
3254 struct workqueue_struct
*wq
= dev_to_wq(dev
);
3255 struct workqueue_attrs
*attrs
;
3258 attrs
= wq_sysfs_prep_attrs(wq
);
3263 if (sscanf(buf
, "%d", &v
) == 1) {
3264 attrs
->no_numa
= !v
;
3265 ret
= apply_workqueue_attrs(wq
, attrs
);
3268 free_workqueue_attrs(attrs
);
3269 return ret
?: count
;
3272 static struct device_attribute wq_sysfs_unbound_attrs
[] = {
3273 __ATTR(pool_ids
, 0444, wq_pool_ids_show
, NULL
),
3274 __ATTR(nice
, 0644, wq_nice_show
, wq_nice_store
),
3275 __ATTR(cpumask
, 0644, wq_cpumask_show
, wq_cpumask_store
),
3276 __ATTR(numa
, 0644, wq_numa_show
, wq_numa_store
),
3280 static struct bus_type wq_subsys
= {
3281 .name
= "workqueue",
3282 .dev_attrs
= wq_sysfs_attrs
,
3285 static int __init
wq_sysfs_init(void)
3287 return subsys_virtual_register(&wq_subsys
, NULL
);
3289 core_initcall(wq_sysfs_init
);
3291 static void wq_device_release(struct device
*dev
)
3293 struct wq_device
*wq_dev
= container_of(dev
, struct wq_device
, dev
);
3299 * workqueue_sysfs_register - make a workqueue visible in sysfs
3300 * @wq: the workqueue to register
3302 * Expose @wq in sysfs under /sys/bus/workqueue/devices.
3303 * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set
3304 * which is the preferred method.
3306 * Workqueue user should use this function directly iff it wants to apply
3307 * workqueue_attrs before making the workqueue visible in sysfs; otherwise,
3308 * apply_workqueue_attrs() may race against userland updating the
3311 * Returns 0 on success, -errno on failure.
3313 int workqueue_sysfs_register(struct workqueue_struct
*wq
)
3315 struct wq_device
*wq_dev
;
3319 * Adjusting max_active or creating new pwqs by applyting
3320 * attributes breaks ordering guarantee. Disallow exposing ordered
3323 if (WARN_ON(wq
->flags
& __WQ_ORDERED
))
3326 wq
->wq_dev
= wq_dev
= kzalloc(sizeof(*wq_dev
), GFP_KERNEL
);
3331 wq_dev
->dev
.bus
= &wq_subsys
;
3332 wq_dev
->dev
.init_name
= wq
->name
;
3333 wq_dev
->dev
.release
= wq_device_release
;
3336 * unbound_attrs are created separately. Suppress uevent until
3337 * everything is ready.
3339 dev_set_uevent_suppress(&wq_dev
->dev
, true);
3341 ret
= device_register(&wq_dev
->dev
);
3348 if (wq
->flags
& WQ_UNBOUND
) {
3349 struct device_attribute
*attr
;
3351 for (attr
= wq_sysfs_unbound_attrs
; attr
->attr
.name
; attr
++) {
3352 ret
= device_create_file(&wq_dev
->dev
, attr
);
3354 device_unregister(&wq_dev
->dev
);
3361 kobject_uevent(&wq_dev
->dev
.kobj
, KOBJ_ADD
);
3366 * workqueue_sysfs_unregister - undo workqueue_sysfs_register()
3367 * @wq: the workqueue to unregister
3369 * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister.
3371 static void workqueue_sysfs_unregister(struct workqueue_struct
*wq
)
3373 struct wq_device
*wq_dev
= wq
->wq_dev
;
3379 device_unregister(&wq_dev
->dev
);
3381 #else /* CONFIG_SYSFS */
3382 static void workqueue_sysfs_unregister(struct workqueue_struct
*wq
) { }
3383 #endif /* CONFIG_SYSFS */
3386 * free_workqueue_attrs - free a workqueue_attrs
3387 * @attrs: workqueue_attrs to free
3389 * Undo alloc_workqueue_attrs().
3391 void free_workqueue_attrs(struct workqueue_attrs
*attrs
)
3394 free_cpumask_var(attrs
->cpumask
);
3400 * alloc_workqueue_attrs - allocate a workqueue_attrs
3401 * @gfp_mask: allocation mask to use
3403 * Allocate a new workqueue_attrs, initialize with default settings and
3404 * return it. Returns NULL on failure.
3406 struct workqueue_attrs
*alloc_workqueue_attrs(gfp_t gfp_mask
)
3408 struct workqueue_attrs
*attrs
;
3410 attrs
= kzalloc(sizeof(*attrs
), gfp_mask
);
3413 if (!alloc_cpumask_var(&attrs
->cpumask
, gfp_mask
))
3416 cpumask_copy(attrs
->cpumask
, cpu_possible_mask
);
3419 free_workqueue_attrs(attrs
);
3423 static void copy_workqueue_attrs(struct workqueue_attrs
*to
,
3424 const struct workqueue_attrs
*from
)
3426 to
->nice
= from
->nice
;
3427 cpumask_copy(to
->cpumask
, from
->cpumask
);
3429 * Unlike hash and equality test, this function doesn't ignore
3430 * ->no_numa as it is used for both pool and wq attrs. Instead,
3431 * get_unbound_pool() explicitly clears ->no_numa after copying.
3433 to
->no_numa
= from
->no_numa
;
3436 /* hash value of the content of @attr */
3437 static u32
wqattrs_hash(const struct workqueue_attrs
*attrs
)
3441 hash
= jhash_1word(attrs
->nice
, hash
);
3442 hash
= jhash(cpumask_bits(attrs
->cpumask
),
3443 BITS_TO_LONGS(nr_cpumask_bits
) * sizeof(long), hash
);
3447 /* content equality test */
3448 static bool wqattrs_equal(const struct workqueue_attrs
*a
,
3449 const struct workqueue_attrs
*b
)
3451 if (a
->nice
!= b
->nice
)
3453 if (!cpumask_equal(a
->cpumask
, b
->cpumask
))
3459 * init_worker_pool - initialize a newly zalloc'd worker_pool
3460 * @pool: worker_pool to initialize
3462 * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs.
3463 * Returns 0 on success, -errno on failure. Even on failure, all fields
3464 * inside @pool proper are initialized and put_unbound_pool() can be called
3465 * on @pool safely to release it.
3467 static int init_worker_pool(struct worker_pool
*pool
)
3469 spin_lock_init(&pool
->lock
);
3472 pool
->node
= NUMA_NO_NODE
;
3473 pool
->flags
|= POOL_DISASSOCIATED
;
3474 INIT_LIST_HEAD(&pool
->worklist
);
3475 INIT_LIST_HEAD(&pool
->idle_list
);
3476 hash_init(pool
->busy_hash
);
3478 init_timer_deferrable(&pool
->idle_timer
);
3479 pool
->idle_timer
.function
= idle_worker_timeout
;
3480 pool
->idle_timer
.data
= (unsigned long)pool
;
3482 setup_timer(&pool
->mayday_timer
, pool_mayday_timeout
,
3483 (unsigned long)pool
);
3485 mutex_init(&pool
->manager_arb
);
3486 mutex_init(&pool
->manager_mutex
);
3487 idr_init(&pool
->worker_idr
);
3489 INIT_HLIST_NODE(&pool
->hash_node
);
3492 /* shouldn't fail above this point */
3493 pool
->attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3499 static void rcu_free_pool(struct rcu_head
*rcu
)
3501 struct worker_pool
*pool
= container_of(rcu
, struct worker_pool
, rcu
);
3503 idr_destroy(&pool
->worker_idr
);
3504 free_workqueue_attrs(pool
->attrs
);
3509 * put_unbound_pool - put a worker_pool
3510 * @pool: worker_pool to put
3512 * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU
3513 * safe manner. get_unbound_pool() calls this function on its failure path
3514 * and this function should be able to release pools which went through,
3515 * successfully or not, init_worker_pool().
3517 * Should be called with wq_pool_mutex held.
3519 static void put_unbound_pool(struct worker_pool
*pool
)
3521 struct worker
*worker
;
3523 lockdep_assert_held(&wq_pool_mutex
);
3529 if (WARN_ON(!(pool
->flags
& POOL_DISASSOCIATED
)) ||
3530 WARN_ON(!list_empty(&pool
->worklist
)))
3533 /* release id and unhash */
3535 idr_remove(&worker_pool_idr
, pool
->id
);
3536 hash_del(&pool
->hash_node
);
3539 * Become the manager and destroy all workers. Grabbing
3540 * manager_arb prevents @pool's workers from blocking on
3543 mutex_lock(&pool
->manager_arb
);
3544 mutex_lock(&pool
->manager_mutex
);
3545 spin_lock_irq(&pool
->lock
);
3547 while ((worker
= first_worker(pool
)))
3548 destroy_worker(worker
);
3549 WARN_ON(pool
->nr_workers
|| pool
->nr_idle
);
3551 spin_unlock_irq(&pool
->lock
);
3552 mutex_unlock(&pool
->manager_mutex
);
3553 mutex_unlock(&pool
->manager_arb
);
3555 /* shut down the timers */
3556 del_timer_sync(&pool
->idle_timer
);
3557 del_timer_sync(&pool
->mayday_timer
);
3559 /* sched-RCU protected to allow dereferences from get_work_pool() */
3560 call_rcu_sched(&pool
->rcu
, rcu_free_pool
);
3564 * get_unbound_pool - get a worker_pool with the specified attributes
3565 * @attrs: the attributes of the worker_pool to get
3567 * Obtain a worker_pool which has the same attributes as @attrs, bump the
3568 * reference count and return it. If there already is a matching
3569 * worker_pool, it will be used; otherwise, this function attempts to
3570 * create a new one. On failure, returns NULL.
3572 * Should be called with wq_pool_mutex held.
3574 static struct worker_pool
*get_unbound_pool(const struct workqueue_attrs
*attrs
)
3576 u32 hash
= wqattrs_hash(attrs
);
3577 struct worker_pool
*pool
;
3580 lockdep_assert_held(&wq_pool_mutex
);
3582 /* do we already have a matching pool? */
3583 hash_for_each_possible(unbound_pool_hash
, pool
, hash_node
, hash
) {
3584 if (wqattrs_equal(pool
->attrs
, attrs
)) {
3590 /* nope, create a new one */
3591 pool
= kzalloc(sizeof(*pool
), GFP_KERNEL
);
3592 if (!pool
|| init_worker_pool(pool
) < 0)
3595 if (workqueue_freezing
)
3596 pool
->flags
|= POOL_FREEZING
;
3598 lockdep_set_subclass(&pool
->lock
, 1); /* see put_pwq() */
3599 copy_workqueue_attrs(pool
->attrs
, attrs
);
3602 * no_numa isn't a worker_pool attribute, always clear it. See
3603 * 'struct workqueue_attrs' comments for detail.
3605 pool
->attrs
->no_numa
= false;
3607 /* if cpumask is contained inside a NUMA node, we belong to that node */
3608 if (wq_numa_enabled
) {
3609 for_each_node(node
) {
3610 if (cpumask_subset(pool
->attrs
->cpumask
,
3611 wq_numa_possible_cpumask
[node
])) {
3618 if (worker_pool_assign_id(pool
) < 0)
3621 /* create and start the initial worker */
3622 if (create_and_start_worker(pool
) < 0)
3626 hash_add(unbound_pool_hash
, &pool
->hash_node
, hash
);
3631 put_unbound_pool(pool
);
3635 static void rcu_free_pwq(struct rcu_head
*rcu
)
3637 kmem_cache_free(pwq_cache
,
3638 container_of(rcu
, struct pool_workqueue
, rcu
));
3642 * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt
3643 * and needs to be destroyed.
3645 static void pwq_unbound_release_workfn(struct work_struct
*work
)
3647 struct pool_workqueue
*pwq
= container_of(work
, struct pool_workqueue
,
3648 unbound_release_work
);
3649 struct workqueue_struct
*wq
= pwq
->wq
;
3650 struct worker_pool
*pool
= pwq
->pool
;
3653 if (WARN_ON_ONCE(!(wq
->flags
& WQ_UNBOUND
)))
3657 * Unlink @pwq. Synchronization against wq->mutex isn't strictly
3658 * necessary on release but do it anyway. It's easier to verify
3659 * and consistent with the linking path.
3661 mutex_lock(&wq
->mutex
);
3662 list_del_rcu(&pwq
->pwqs_node
);
3663 is_last
= list_empty(&wq
->pwqs
);
3664 mutex_unlock(&wq
->mutex
);
3666 mutex_lock(&wq_pool_mutex
);
3667 put_unbound_pool(pool
);
3668 mutex_unlock(&wq_pool_mutex
);
3670 call_rcu_sched(&pwq
->rcu
, rcu_free_pwq
);
3673 * If we're the last pwq going away, @wq is already dead and no one
3674 * is gonna access it anymore. Free it.
3677 free_workqueue_attrs(wq
->unbound_attrs
);
3683 * pwq_adjust_max_active - update a pwq's max_active to the current setting
3684 * @pwq: target pool_workqueue
3686 * If @pwq isn't freezing, set @pwq->max_active to the associated
3687 * workqueue's saved_max_active and activate delayed work items
3688 * accordingly. If @pwq is freezing, clear @pwq->max_active to zero.
3690 static void pwq_adjust_max_active(struct pool_workqueue
*pwq
)
3692 struct workqueue_struct
*wq
= pwq
->wq
;
3693 bool freezable
= wq
->flags
& WQ_FREEZABLE
;
3695 /* for @wq->saved_max_active */
3696 lockdep_assert_held(&wq
->mutex
);
3698 /* fast exit for non-freezable wqs */
3699 if (!freezable
&& pwq
->max_active
== wq
->saved_max_active
)
3702 spin_lock_irq(&pwq
->pool
->lock
);
3704 if (!freezable
|| !(pwq
->pool
->flags
& POOL_FREEZING
)) {
3705 pwq
->max_active
= wq
->saved_max_active
;
3707 while (!list_empty(&pwq
->delayed_works
) &&
3708 pwq
->nr_active
< pwq
->max_active
)
3709 pwq_activate_first_delayed(pwq
);
3712 * Need to kick a worker after thawed or an unbound wq's
3713 * max_active is bumped. It's a slow path. Do it always.
3715 wake_up_worker(pwq
->pool
);
3717 pwq
->max_active
= 0;
3720 spin_unlock_irq(&pwq
->pool
->lock
);
3723 /* initialize newly alloced @pwq which is associated with @wq and @pool */
3724 static void init_pwq(struct pool_workqueue
*pwq
, struct workqueue_struct
*wq
,
3725 struct worker_pool
*pool
)
3727 BUG_ON((unsigned long)pwq
& WORK_STRUCT_FLAG_MASK
);
3729 memset(pwq
, 0, sizeof(*pwq
));
3733 pwq
->flush_color
= -1;
3735 INIT_LIST_HEAD(&pwq
->delayed_works
);
3736 INIT_LIST_HEAD(&pwq
->pwqs_node
);
3737 INIT_LIST_HEAD(&pwq
->mayday_node
);
3738 INIT_WORK(&pwq
->unbound_release_work
, pwq_unbound_release_workfn
);
3741 /* sync @pwq with the current state of its associated wq and link it */
3742 static void link_pwq(struct pool_workqueue
*pwq
)
3744 struct workqueue_struct
*wq
= pwq
->wq
;
3746 lockdep_assert_held(&wq
->mutex
);
3748 /* may be called multiple times, ignore if already linked */
3749 if (!list_empty(&pwq
->pwqs_node
))
3753 * Set the matching work_color. This is synchronized with
3754 * wq->mutex to avoid confusing flush_workqueue().
3756 pwq
->work_color
= wq
->work_color
;
3758 /* sync max_active to the current setting */
3759 pwq_adjust_max_active(pwq
);
3762 list_add_rcu(&pwq
->pwqs_node
, &wq
->pwqs
);
3765 /* obtain a pool matching @attr and create a pwq associating the pool and @wq */
3766 static struct pool_workqueue
*alloc_unbound_pwq(struct workqueue_struct
*wq
,
3767 const struct workqueue_attrs
*attrs
)
3769 struct worker_pool
*pool
;
3770 struct pool_workqueue
*pwq
;
3772 lockdep_assert_held(&wq_pool_mutex
);
3774 pool
= get_unbound_pool(attrs
);
3778 pwq
= kmem_cache_alloc_node(pwq_cache
, GFP_KERNEL
, pool
->node
);
3780 put_unbound_pool(pool
);
3784 init_pwq(pwq
, wq
, pool
);
3788 /* undo alloc_unbound_pwq(), used only in the error path */
3789 static void free_unbound_pwq(struct pool_workqueue
*pwq
)
3791 lockdep_assert_held(&wq_pool_mutex
);
3794 put_unbound_pool(pwq
->pool
);
3795 kmem_cache_free(pwq_cache
, pwq
);
3800 * wq_calc_node_mask - calculate a wq_attrs' cpumask for the specified node
3801 * @attrs: the wq_attrs of interest
3802 * @node: the target NUMA node
3803 * @cpu_going_down: if >= 0, the CPU to consider as offline
3804 * @cpumask: outarg, the resulting cpumask
3806 * Calculate the cpumask a workqueue with @attrs should use on @node. If
3807 * @cpu_going_down is >= 0, that cpu is considered offline during
3808 * calculation. The result is stored in @cpumask. This function returns
3809 * %true if the resulting @cpumask is different from @attrs->cpumask,
3812 * If NUMA affinity is not enabled, @attrs->cpumask is always used. If
3813 * enabled and @node has online CPUs requested by @attrs, the returned
3814 * cpumask is the intersection of the possible CPUs of @node and
3817 * The caller is responsible for ensuring that the cpumask of @node stays
3820 static bool wq_calc_node_cpumask(const struct workqueue_attrs
*attrs
, int node
,
3821 int cpu_going_down
, cpumask_t
*cpumask
)
3823 if (!wq_numa_enabled
|| attrs
->no_numa
)
3826 /* does @node have any online CPUs @attrs wants? */
3827 cpumask_and(cpumask
, cpumask_of_node(node
), attrs
->cpumask
);
3828 if (cpu_going_down
>= 0)
3829 cpumask_clear_cpu(cpu_going_down
, cpumask
);
3831 if (cpumask_empty(cpumask
))
3834 /* yeap, return possible CPUs in @node that @attrs wants */
3835 cpumask_and(cpumask
, attrs
->cpumask
, wq_numa_possible_cpumask
[node
]);
3836 return !cpumask_equal(cpumask
, attrs
->cpumask
);
3839 cpumask_copy(cpumask
, attrs
->cpumask
);
3843 /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */
3844 static struct pool_workqueue
*numa_pwq_tbl_install(struct workqueue_struct
*wq
,
3846 struct pool_workqueue
*pwq
)
3848 struct pool_workqueue
*old_pwq
;
3850 lockdep_assert_held(&wq
->mutex
);
3852 /* link_pwq() can handle duplicate calls */
3855 old_pwq
= rcu_access_pointer(wq
->numa_pwq_tbl
[node
]);
3856 rcu_assign_pointer(wq
->numa_pwq_tbl
[node
], pwq
);
3861 * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue
3862 * @wq: the target workqueue
3863 * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs()
3865 * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA
3866 * machines, this function maps a separate pwq to each NUMA node with
3867 * possibles CPUs in @attrs->cpumask so that work items are affine to the
3868 * NUMA node it was issued on. Older pwqs are released as in-flight work
3869 * items finish. Note that a work item which repeatedly requeues itself
3870 * back-to-back will stay on its current pwq.
3872 * Performs GFP_KERNEL allocations. Returns 0 on success and -errno on
3875 int apply_workqueue_attrs(struct workqueue_struct
*wq
,
3876 const struct workqueue_attrs
*attrs
)
3878 struct workqueue_attrs
*new_attrs
, *tmp_attrs
;
3879 struct pool_workqueue
**pwq_tbl
, *dfl_pwq
;
3882 /* only unbound workqueues can change attributes */
3883 if (WARN_ON(!(wq
->flags
& WQ_UNBOUND
)))
3886 /* creating multiple pwqs breaks ordering guarantee */
3887 if (WARN_ON((wq
->flags
& __WQ_ORDERED
) && !list_empty(&wq
->pwqs
)))
3890 pwq_tbl
= kzalloc(wq_numa_tbl_len
* sizeof(pwq_tbl
[0]), GFP_KERNEL
);
3891 new_attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3892 tmp_attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
3893 if (!pwq_tbl
|| !new_attrs
|| !tmp_attrs
)
3896 /* make a copy of @attrs and sanitize it */
3897 copy_workqueue_attrs(new_attrs
, attrs
);
3898 cpumask_and(new_attrs
->cpumask
, new_attrs
->cpumask
, cpu_possible_mask
);
3901 * We may create multiple pwqs with differing cpumasks. Make a
3902 * copy of @new_attrs which will be modified and used to obtain
3905 copy_workqueue_attrs(tmp_attrs
, new_attrs
);
3908 * CPUs should stay stable across pwq creations and installations.
3909 * Pin CPUs, determine the target cpumask for each node and create
3914 mutex_lock(&wq_pool_mutex
);
3917 * If something goes wrong during CPU up/down, we'll fall back to
3918 * the default pwq covering whole @attrs->cpumask. Always create
3919 * it even if we don't use it immediately.
3921 dfl_pwq
= alloc_unbound_pwq(wq
, new_attrs
);
3925 for_each_node(node
) {
3926 if (wq_calc_node_cpumask(attrs
, node
, -1, tmp_attrs
->cpumask
)) {
3927 pwq_tbl
[node
] = alloc_unbound_pwq(wq
, tmp_attrs
);
3932 pwq_tbl
[node
] = dfl_pwq
;
3936 mutex_unlock(&wq_pool_mutex
);
3938 /* all pwqs have been created successfully, let's install'em */
3939 mutex_lock(&wq
->mutex
);
3941 copy_workqueue_attrs(wq
->unbound_attrs
, new_attrs
);
3943 /* save the previous pwq and install the new one */
3945 pwq_tbl
[node
] = numa_pwq_tbl_install(wq
, node
, pwq_tbl
[node
]);
3947 /* @dfl_pwq might not have been used, ensure it's linked */
3949 swap(wq
->dfl_pwq
, dfl_pwq
);
3951 mutex_unlock(&wq
->mutex
);
3953 /* put the old pwqs */
3955 put_pwq_unlocked(pwq_tbl
[node
]);
3956 put_pwq_unlocked(dfl_pwq
);
3962 free_workqueue_attrs(tmp_attrs
);
3963 free_workqueue_attrs(new_attrs
);
3968 free_unbound_pwq(dfl_pwq
);
3970 if (pwq_tbl
&& pwq_tbl
[node
] != dfl_pwq
)
3971 free_unbound_pwq(pwq_tbl
[node
]);
3972 mutex_unlock(&wq_pool_mutex
);
3980 * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug
3981 * @wq: the target workqueue
3982 * @cpu: the CPU coming up or going down
3983 * @online: whether @cpu is coming up or going down
3985 * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and
3986 * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of
3989 * If NUMA affinity can't be adjusted due to memory allocation failure, it
3990 * falls back to @wq->dfl_pwq which may not be optimal but is always
3993 * Note that when the last allowed CPU of a NUMA node goes offline for a
3994 * workqueue with a cpumask spanning multiple nodes, the workers which were
3995 * already executing the work items for the workqueue will lose their CPU
3996 * affinity and may execute on any CPU. This is similar to how per-cpu
3997 * workqueues behave on CPU_DOWN. If a workqueue user wants strict
3998 * affinity, it's the user's responsibility to flush the work item from
4001 static void wq_update_unbound_numa(struct workqueue_struct
*wq
, int cpu
,
4004 int node
= cpu_to_node(cpu
);
4005 int cpu_off
= online
? -1 : cpu
;
4006 struct pool_workqueue
*old_pwq
= NULL
, *pwq
;
4007 struct workqueue_attrs
*target_attrs
;
4010 lockdep_assert_held(&wq_pool_mutex
);
4012 if (!wq_numa_enabled
|| !(wq
->flags
& WQ_UNBOUND
))
4016 * We don't wanna alloc/free wq_attrs for each wq for each CPU.
4017 * Let's use a preallocated one. The following buf is protected by
4018 * CPU hotplug exclusion.
4020 target_attrs
= wq_update_unbound_numa_attrs_buf
;
4021 cpumask
= target_attrs
->cpumask
;
4023 mutex_lock(&wq
->mutex
);
4024 if (wq
->unbound_attrs
->no_numa
)
4027 copy_workqueue_attrs(target_attrs
, wq
->unbound_attrs
);
4028 pwq
= unbound_pwq_by_node(wq
, node
);
4031 * Let's determine what needs to be done. If the target cpumask is
4032 * different from wq's, we need to compare it to @pwq's and create
4033 * a new one if they don't match. If the target cpumask equals
4034 * wq's, the default pwq should be used. If @pwq is already the
4035 * default one, nothing to do; otherwise, install the default one.
4037 if (wq_calc_node_cpumask(wq
->unbound_attrs
, node
, cpu_off
, cpumask
)) {
4038 if (cpumask_equal(cpumask
, pwq
->pool
->attrs
->cpumask
))
4041 if (pwq
== wq
->dfl_pwq
)
4047 mutex_unlock(&wq
->mutex
);
4049 /* create a new pwq */
4050 pwq
= alloc_unbound_pwq(wq
, target_attrs
);
4052 pr_warning("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n",
4058 * Install the new pwq. As this function is called only from CPU
4059 * hotplug callbacks and applying a new attrs is wrapped with
4060 * get/put_online_cpus(), @wq->unbound_attrs couldn't have changed
4063 mutex_lock(&wq
->mutex
);
4064 old_pwq
= numa_pwq_tbl_install(wq
, node
, pwq
);
4068 spin_lock_irq(&wq
->dfl_pwq
->pool
->lock
);
4069 get_pwq(wq
->dfl_pwq
);
4070 spin_unlock_irq(&wq
->dfl_pwq
->pool
->lock
);
4071 old_pwq
= numa_pwq_tbl_install(wq
, node
, wq
->dfl_pwq
);
4073 mutex_unlock(&wq
->mutex
);
4074 put_pwq_unlocked(old_pwq
);
4077 static int alloc_and_link_pwqs(struct workqueue_struct
*wq
)
4079 bool highpri
= wq
->flags
& WQ_HIGHPRI
;
4082 if (!(wq
->flags
& WQ_UNBOUND
)) {
4083 wq
->cpu_pwqs
= alloc_percpu(struct pool_workqueue
);
4087 for_each_possible_cpu(cpu
) {
4088 struct pool_workqueue
*pwq
=
4089 per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
4090 struct worker_pool
*cpu_pools
=
4091 per_cpu(cpu_worker_pools
, cpu
);
4093 init_pwq(pwq
, wq
, &cpu_pools
[highpri
]);
4095 mutex_lock(&wq
->mutex
);
4097 mutex_unlock(&wq
->mutex
);
4101 return apply_workqueue_attrs(wq
, unbound_std_wq_attrs
[highpri
]);
4105 static int wq_clamp_max_active(int max_active
, unsigned int flags
,
4108 int lim
= flags
& WQ_UNBOUND
? WQ_UNBOUND_MAX_ACTIVE
: WQ_MAX_ACTIVE
;
4110 if (max_active
< 1 || max_active
> lim
)
4111 pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n",
4112 max_active
, name
, 1, lim
);
4114 return clamp_val(max_active
, 1, lim
);
4117 struct workqueue_struct
*__alloc_workqueue_key(const char *fmt
,
4120 struct lock_class_key
*key
,
4121 const char *lock_name
, ...)
4123 size_t tbl_size
= 0;
4125 struct workqueue_struct
*wq
;
4126 struct pool_workqueue
*pwq
;
4128 /* see the comment above the definition of WQ_POWER_EFFICIENT */
4129 if ((flags
& WQ_POWER_EFFICIENT
) && wq_power_efficient
)
4130 flags
|= WQ_UNBOUND
;
4132 /* allocate wq and format name */
4133 if (flags
& WQ_UNBOUND
)
4134 tbl_size
= wq_numa_tbl_len
* sizeof(wq
->numa_pwq_tbl
[0]);
4136 wq
= kzalloc(sizeof(*wq
) + tbl_size
, GFP_KERNEL
);
4140 if (flags
& WQ_UNBOUND
) {
4141 wq
->unbound_attrs
= alloc_workqueue_attrs(GFP_KERNEL
);
4142 if (!wq
->unbound_attrs
)
4146 va_start(args
, lock_name
);
4147 vsnprintf(wq
->name
, sizeof(wq
->name
), fmt
, args
);
4150 max_active
= max_active
?: WQ_DFL_ACTIVE
;
4151 max_active
= wq_clamp_max_active(max_active
, flags
, wq
->name
);
4155 wq
->saved_max_active
= max_active
;
4156 mutex_init(&wq
->mutex
);
4157 atomic_set(&wq
->nr_pwqs_to_flush
, 0);
4158 INIT_LIST_HEAD(&wq
->pwqs
);
4159 INIT_LIST_HEAD(&wq
->flusher_queue
);
4160 INIT_LIST_HEAD(&wq
->flusher_overflow
);
4161 INIT_LIST_HEAD(&wq
->maydays
);
4163 lockdep_init_map(&wq
->lockdep_map
, lock_name
, key
, 0);
4164 INIT_LIST_HEAD(&wq
->list
);
4166 if (alloc_and_link_pwqs(wq
) < 0)
4170 * Workqueues which may be used during memory reclaim should
4171 * have a rescuer to guarantee forward progress.
4173 if (flags
& WQ_MEM_RECLAIM
) {
4174 struct worker
*rescuer
;
4176 rescuer
= alloc_worker();
4180 rescuer
->rescue_wq
= wq
;
4181 rescuer
->task
= kthread_create(rescuer_thread
, rescuer
, "%s",
4183 if (IS_ERR(rescuer
->task
)) {
4188 wq
->rescuer
= rescuer
;
4189 rescuer
->task
->flags
|= PF_NO_SETAFFINITY
;
4190 wake_up_process(rescuer
->task
);
4193 if ((wq
->flags
& WQ_SYSFS
) && workqueue_sysfs_register(wq
))
4197 * wq_pool_mutex protects global freeze state and workqueues list.
4198 * Grab it, adjust max_active and add the new @wq to workqueues
4201 mutex_lock(&wq_pool_mutex
);
4203 mutex_lock(&wq
->mutex
);
4204 for_each_pwq(pwq
, wq
)
4205 pwq_adjust_max_active(pwq
);
4206 mutex_unlock(&wq
->mutex
);
4208 list_add(&wq
->list
, &workqueues
);
4210 mutex_unlock(&wq_pool_mutex
);
4215 free_workqueue_attrs(wq
->unbound_attrs
);
4219 destroy_workqueue(wq
);
4222 EXPORT_SYMBOL_GPL(__alloc_workqueue_key
);
4225 * destroy_workqueue - safely terminate a workqueue
4226 * @wq: target workqueue
4228 * Safely destroy a workqueue. All work currently pending will be done first.
4230 void destroy_workqueue(struct workqueue_struct
*wq
)
4232 struct pool_workqueue
*pwq
;
4235 /* drain it before proceeding with destruction */
4236 drain_workqueue(wq
);
4239 mutex_lock(&wq
->mutex
);
4240 for_each_pwq(pwq
, wq
) {
4243 for (i
= 0; i
< WORK_NR_COLORS
; i
++) {
4244 if (WARN_ON(pwq
->nr_in_flight
[i
])) {
4245 mutex_unlock(&wq
->mutex
);
4250 if (WARN_ON((pwq
!= wq
->dfl_pwq
) && (pwq
->refcnt
> 1)) ||
4251 WARN_ON(pwq
->nr_active
) ||
4252 WARN_ON(!list_empty(&pwq
->delayed_works
))) {
4253 mutex_unlock(&wq
->mutex
);
4257 mutex_unlock(&wq
->mutex
);
4260 * wq list is used to freeze wq, remove from list after
4261 * flushing is complete in case freeze races us.
4263 mutex_lock(&wq_pool_mutex
);
4264 list_del_init(&wq
->list
);
4265 mutex_unlock(&wq_pool_mutex
);
4267 workqueue_sysfs_unregister(wq
);
4270 kthread_stop(wq
->rescuer
->task
);
4275 if (!(wq
->flags
& WQ_UNBOUND
)) {
4277 * The base ref is never dropped on per-cpu pwqs. Directly
4278 * free the pwqs and wq.
4280 free_percpu(wq
->cpu_pwqs
);
4284 * We're the sole accessor of @wq at this point. Directly
4285 * access numa_pwq_tbl[] and dfl_pwq to put the base refs.
4286 * @wq will be freed when the last pwq is released.
4288 for_each_node(node
) {
4289 pwq
= rcu_access_pointer(wq
->numa_pwq_tbl
[node
]);
4290 RCU_INIT_POINTER(wq
->numa_pwq_tbl
[node
], NULL
);
4291 put_pwq_unlocked(pwq
);
4295 * Put dfl_pwq. @wq may be freed any time after dfl_pwq is
4296 * put. Don't access it afterwards.
4300 put_pwq_unlocked(pwq
);
4303 EXPORT_SYMBOL_GPL(destroy_workqueue
);
4306 * workqueue_set_max_active - adjust max_active of a workqueue
4307 * @wq: target workqueue
4308 * @max_active: new max_active value.
4310 * Set max_active of @wq to @max_active.
4313 * Don't call from IRQ context.
4315 void workqueue_set_max_active(struct workqueue_struct
*wq
, int max_active
)
4317 struct pool_workqueue
*pwq
;
4319 /* disallow meddling with max_active for ordered workqueues */
4320 if (WARN_ON(wq
->flags
& __WQ_ORDERED
))
4323 max_active
= wq_clamp_max_active(max_active
, wq
->flags
, wq
->name
);
4325 mutex_lock(&wq
->mutex
);
4327 wq
->saved_max_active
= max_active
;
4329 for_each_pwq(pwq
, wq
)
4330 pwq_adjust_max_active(pwq
);
4332 mutex_unlock(&wq
->mutex
);
4334 EXPORT_SYMBOL_GPL(workqueue_set_max_active
);
4337 * current_is_workqueue_rescuer - is %current workqueue rescuer?
4339 * Determine whether %current is a workqueue rescuer. Can be used from
4340 * work functions to determine whether it's being run off the rescuer task.
4342 bool current_is_workqueue_rescuer(void)
4344 struct worker
*worker
= current_wq_worker();
4346 return worker
&& worker
->rescue_wq
;
4350 * workqueue_congested - test whether a workqueue is congested
4351 * @cpu: CPU in question
4352 * @wq: target workqueue
4354 * Test whether @wq's cpu workqueue for @cpu is congested. There is
4355 * no synchronization around this function and the test result is
4356 * unreliable and only useful as advisory hints or for debugging.
4358 * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU.
4359 * Note that both per-cpu and unbound workqueues may be associated with
4360 * multiple pool_workqueues which have separate congested states. A
4361 * workqueue being congested on one CPU doesn't mean the workqueue is also
4362 * contested on other CPUs / NUMA nodes.
4365 * %true if congested, %false otherwise.
4367 bool workqueue_congested(int cpu
, struct workqueue_struct
*wq
)
4369 struct pool_workqueue
*pwq
;
4372 rcu_read_lock_sched();
4374 if (cpu
== WORK_CPU_UNBOUND
)
4375 cpu
= smp_processor_id();
4377 if (!(wq
->flags
& WQ_UNBOUND
))
4378 pwq
= per_cpu_ptr(wq
->cpu_pwqs
, cpu
);
4380 pwq
= unbound_pwq_by_node(wq
, cpu_to_node(cpu
));
4382 ret
= !list_empty(&pwq
->delayed_works
);
4383 rcu_read_unlock_sched();
4387 EXPORT_SYMBOL_GPL(workqueue_congested
);
4390 * work_busy - test whether a work is currently pending or running
4391 * @work: the work to be tested
4393 * Test whether @work is currently pending or running. There is no
4394 * synchronization around this function and the test result is
4395 * unreliable and only useful as advisory hints or for debugging.
4398 * OR'd bitmask of WORK_BUSY_* bits.
4400 unsigned int work_busy(struct work_struct
*work
)
4402 struct worker_pool
*pool
;
4403 unsigned long flags
;
4404 unsigned int ret
= 0;
4406 if (work_pending(work
))
4407 ret
|= WORK_BUSY_PENDING
;
4409 local_irq_save(flags
);
4410 pool
= get_work_pool(work
);
4412 spin_lock(&pool
->lock
);
4413 if (find_worker_executing_work(pool
, work
))
4414 ret
|= WORK_BUSY_RUNNING
;
4415 spin_unlock(&pool
->lock
);
4417 local_irq_restore(flags
);
4421 EXPORT_SYMBOL_GPL(work_busy
);
4424 * set_worker_desc - set description for the current work item
4425 * @fmt: printf-style format string
4426 * @...: arguments for the format string
4428 * This function can be called by a running work function to describe what
4429 * the work item is about. If the worker task gets dumped, this
4430 * information will be printed out together to help debugging. The
4431 * description can be at most WORKER_DESC_LEN including the trailing '\0'.
4433 void set_worker_desc(const char *fmt
, ...)
4435 struct worker
*worker
= current_wq_worker();
4439 va_start(args
, fmt
);
4440 vsnprintf(worker
->desc
, sizeof(worker
->desc
), fmt
, args
);
4442 worker
->desc_valid
= true;
4447 * print_worker_info - print out worker information and description
4448 * @log_lvl: the log level to use when printing
4449 * @task: target task
4451 * If @task is a worker and currently executing a work item, print out the
4452 * name of the workqueue being serviced and worker description set with
4453 * set_worker_desc() by the currently executing work item.
4455 * This function can be safely called on any task as long as the
4456 * task_struct itself is accessible. While safe, this function isn't
4457 * synchronized and may print out mixups or garbages of limited length.
4459 void print_worker_info(const char *log_lvl
, struct task_struct
*task
)
4461 work_func_t
*fn
= NULL
;
4462 char name
[WQ_NAME_LEN
] = { };
4463 char desc
[WORKER_DESC_LEN
] = { };
4464 struct pool_workqueue
*pwq
= NULL
;
4465 struct workqueue_struct
*wq
= NULL
;
4466 bool desc_valid
= false;
4467 struct worker
*worker
;
4469 if (!(task
->flags
& PF_WQ_WORKER
))
4473 * This function is called without any synchronization and @task
4474 * could be in any state. Be careful with dereferences.
4476 worker
= probe_kthread_data(task
);
4479 * Carefully copy the associated workqueue's workfn and name. Keep
4480 * the original last '\0' in case the original contains garbage.
4482 probe_kernel_read(&fn
, &worker
->current_func
, sizeof(fn
));
4483 probe_kernel_read(&pwq
, &worker
->current_pwq
, sizeof(pwq
));
4484 probe_kernel_read(&wq
, &pwq
->wq
, sizeof(wq
));
4485 probe_kernel_read(name
, wq
->name
, sizeof(name
) - 1);
4487 /* copy worker description */
4488 probe_kernel_read(&desc_valid
, &worker
->desc_valid
, sizeof(desc_valid
));
4490 probe_kernel_read(desc
, worker
->desc
, sizeof(desc
) - 1);
4492 if (fn
|| name
[0] || desc
[0]) {
4493 printk("%sWorkqueue: %s %pf", log_lvl
, name
, fn
);
4495 pr_cont(" (%s)", desc
);
4503 * There are two challenges in supporting CPU hotplug. Firstly, there
4504 * are a lot of assumptions on strong associations among work, pwq and
4505 * pool which make migrating pending and scheduled works very
4506 * difficult to implement without impacting hot paths. Secondly,
4507 * worker pools serve mix of short, long and very long running works making
4508 * blocked draining impractical.
4510 * This is solved by allowing the pools to be disassociated from the CPU
4511 * running as an unbound one and allowing it to be reattached later if the
4512 * cpu comes back online.
4515 static void wq_unbind_fn(struct work_struct
*work
)
4517 int cpu
= smp_processor_id();
4518 struct worker_pool
*pool
;
4519 struct worker
*worker
;
4522 for_each_cpu_worker_pool(pool
, cpu
) {
4523 WARN_ON_ONCE(cpu
!= smp_processor_id());
4525 mutex_lock(&pool
->manager_mutex
);
4526 spin_lock_irq(&pool
->lock
);
4529 * We've blocked all manager operations. Make all workers
4530 * unbound and set DISASSOCIATED. Before this, all workers
4531 * except for the ones which are still executing works from
4532 * before the last CPU down must be on the cpu. After
4533 * this, they may become diasporas.
4535 for_each_pool_worker(worker
, wi
, pool
)
4536 worker
->flags
|= WORKER_UNBOUND
;
4538 pool
->flags
|= POOL_DISASSOCIATED
;
4540 spin_unlock_irq(&pool
->lock
);
4541 mutex_unlock(&pool
->manager_mutex
);
4544 * Call schedule() so that we cross rq->lock and thus can
4545 * guarantee sched callbacks see the %WORKER_UNBOUND flag.
4546 * This is necessary as scheduler callbacks may be invoked
4552 * Sched callbacks are disabled now. Zap nr_running.
4553 * After this, nr_running stays zero and need_more_worker()
4554 * and keep_working() are always true as long as the
4555 * worklist is not empty. This pool now behaves as an
4556 * unbound (in terms of concurrency management) pool which
4557 * are served by workers tied to the pool.
4559 atomic_set(&pool
->nr_running
, 0);
4562 * With concurrency management just turned off, a busy
4563 * worker blocking could lead to lengthy stalls. Kick off
4564 * unbound chain execution of currently pending work items.
4566 spin_lock_irq(&pool
->lock
);
4567 wake_up_worker(pool
);
4568 spin_unlock_irq(&pool
->lock
);
4573 * rebind_workers - rebind all workers of a pool to the associated CPU
4574 * @pool: pool of interest
4576 * @pool->cpu is coming online. Rebind all workers to the CPU.
4578 static void rebind_workers(struct worker_pool
*pool
)
4580 struct worker
*worker
;
4583 lockdep_assert_held(&pool
->manager_mutex
);
4586 * Restore CPU affinity of all workers. As all idle workers should
4587 * be on the run-queue of the associated CPU before any local
4588 * wake-ups for concurrency management happen, restore CPU affinty
4589 * of all workers first and then clear UNBOUND. As we're called
4590 * from CPU_ONLINE, the following shouldn't fail.
4592 for_each_pool_worker(worker
, wi
, pool
)
4593 WARN_ON_ONCE(set_cpus_allowed_ptr(worker
->task
,
4594 pool
->attrs
->cpumask
) < 0);
4596 spin_lock_irq(&pool
->lock
);
4598 for_each_pool_worker(worker
, wi
, pool
) {
4599 unsigned int worker_flags
= worker
->flags
;
4602 * A bound idle worker should actually be on the runqueue
4603 * of the associated CPU for local wake-ups targeting it to
4604 * work. Kick all idle workers so that they migrate to the
4605 * associated CPU. Doing this in the same loop as
4606 * replacing UNBOUND with REBOUND is safe as no worker will
4607 * be bound before @pool->lock is released.
4609 if (worker_flags
& WORKER_IDLE
)
4610 wake_up_process(worker
->task
);
4613 * We want to clear UNBOUND but can't directly call
4614 * worker_clr_flags() or adjust nr_running. Atomically
4615 * replace UNBOUND with another NOT_RUNNING flag REBOUND.
4616 * @worker will clear REBOUND using worker_clr_flags() when
4617 * it initiates the next execution cycle thus restoring
4618 * concurrency management. Note that when or whether
4619 * @worker clears REBOUND doesn't affect correctness.
4621 * ACCESS_ONCE() is necessary because @worker->flags may be
4622 * tested without holding any lock in
4623 * wq_worker_waking_up(). Without it, NOT_RUNNING test may
4624 * fail incorrectly leading to premature concurrency
4625 * management operations.
4627 WARN_ON_ONCE(!(worker_flags
& WORKER_UNBOUND
));
4628 worker_flags
|= WORKER_REBOUND
;
4629 worker_flags
&= ~WORKER_UNBOUND
;
4630 ACCESS_ONCE(worker
->flags
) = worker_flags
;
4633 spin_unlock_irq(&pool
->lock
);
4637 * restore_unbound_workers_cpumask - restore cpumask of unbound workers
4638 * @pool: unbound pool of interest
4639 * @cpu: the CPU which is coming up
4641 * An unbound pool may end up with a cpumask which doesn't have any online
4642 * CPUs. When a worker of such pool get scheduled, the scheduler resets
4643 * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any
4644 * online CPU before, cpus_allowed of all its workers should be restored.
4646 static void restore_unbound_workers_cpumask(struct worker_pool
*pool
, int cpu
)
4648 static cpumask_t cpumask
;
4649 struct worker
*worker
;
4652 lockdep_assert_held(&pool
->manager_mutex
);
4654 /* is @cpu allowed for @pool? */
4655 if (!cpumask_test_cpu(cpu
, pool
->attrs
->cpumask
))
4658 /* is @cpu the only online CPU? */
4659 cpumask_and(&cpumask
, pool
->attrs
->cpumask
, cpu_online_mask
);
4660 if (cpumask_weight(&cpumask
) != 1)
4663 /* as we're called from CPU_ONLINE, the following shouldn't fail */
4664 for_each_pool_worker(worker
, wi
, pool
)
4665 WARN_ON_ONCE(set_cpus_allowed_ptr(worker
->task
,
4666 pool
->attrs
->cpumask
) < 0);
4670 * Workqueues should be brought up before normal priority CPU notifiers.
4671 * This will be registered high priority CPU notifier.
4673 static int workqueue_cpu_up_callback(struct notifier_block
*nfb
,
4674 unsigned long action
,
4677 int cpu
= (unsigned long)hcpu
;
4678 struct worker_pool
*pool
;
4679 struct workqueue_struct
*wq
;
4682 switch (action
& ~CPU_TASKS_FROZEN
) {
4683 case CPU_UP_PREPARE
:
4684 for_each_cpu_worker_pool(pool
, cpu
) {
4685 if (pool
->nr_workers
)
4687 if (create_and_start_worker(pool
) < 0)
4692 case CPU_DOWN_FAILED
:
4694 mutex_lock(&wq_pool_mutex
);
4696 for_each_pool(pool
, pi
) {
4697 mutex_lock(&pool
->manager_mutex
);
4699 if (pool
->cpu
== cpu
) {
4700 spin_lock_irq(&pool
->lock
);
4701 pool
->flags
&= ~POOL_DISASSOCIATED
;
4702 spin_unlock_irq(&pool
->lock
);
4704 rebind_workers(pool
);
4705 } else if (pool
->cpu
< 0) {
4706 restore_unbound_workers_cpumask(pool
, cpu
);
4709 mutex_unlock(&pool
->manager_mutex
);
4712 /* update NUMA affinity of unbound workqueues */
4713 list_for_each_entry(wq
, &workqueues
, list
)
4714 wq_update_unbound_numa(wq
, cpu
, true);
4716 mutex_unlock(&wq_pool_mutex
);
4723 * Workqueues should be brought down after normal priority CPU notifiers.
4724 * This will be registered as low priority CPU notifier.
4726 static int workqueue_cpu_down_callback(struct notifier_block
*nfb
,
4727 unsigned long action
,
4730 int cpu
= (unsigned long)hcpu
;
4731 struct work_struct unbind_work
;
4732 struct workqueue_struct
*wq
;
4734 switch (action
& ~CPU_TASKS_FROZEN
) {
4735 case CPU_DOWN_PREPARE
:
4736 /* unbinding per-cpu workers should happen on the local CPU */
4737 INIT_WORK_ONSTACK(&unbind_work
, wq_unbind_fn
);
4738 queue_work_on(cpu
, system_highpri_wq
, &unbind_work
);
4740 /* update NUMA affinity of unbound workqueues */
4741 mutex_lock(&wq_pool_mutex
);
4742 list_for_each_entry(wq
, &workqueues
, list
)
4743 wq_update_unbound_numa(wq
, cpu
, false);
4744 mutex_unlock(&wq_pool_mutex
);
4746 /* wait for per-cpu unbinding to finish */
4747 flush_work(&unbind_work
);
4755 struct work_for_cpu
{
4756 struct work_struct work
;
4762 static void work_for_cpu_fn(struct work_struct
*work
)
4764 struct work_for_cpu
*wfc
= container_of(work
, struct work_for_cpu
, work
);
4766 wfc
->ret
= wfc
->fn(wfc
->arg
);
4770 * work_on_cpu - run a function in user context on a particular cpu
4771 * @cpu: the cpu to run on
4772 * @fn: the function to run
4773 * @arg: the function arg
4775 * This will return the value @fn returns.
4776 * It is up to the caller to ensure that the cpu doesn't go offline.
4777 * The caller must not hold any locks which would prevent @fn from completing.
4779 long work_on_cpu(int cpu
, long (*fn
)(void *), void *arg
)
4781 struct work_for_cpu wfc
= { .fn
= fn
, .arg
= arg
};
4783 INIT_WORK_ONSTACK(&wfc
.work
, work_for_cpu_fn
);
4784 schedule_work_on(cpu
, &wfc
.work
);
4787 * The work item is on-stack and can't lead to deadlock through
4788 * flushing. Use __flush_work() to avoid spurious lockdep warnings
4789 * when work_on_cpu()s are nested.
4791 __flush_work(&wfc
.work
);
4795 EXPORT_SYMBOL_GPL(work_on_cpu
);
4796 #endif /* CONFIG_SMP */
4798 #ifdef CONFIG_FREEZER
4801 * freeze_workqueues_begin - begin freezing workqueues
4803 * Start freezing workqueues. After this function returns, all freezable
4804 * workqueues will queue new works to their delayed_works list instead of
4808 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4810 void freeze_workqueues_begin(void)
4812 struct worker_pool
*pool
;
4813 struct workqueue_struct
*wq
;
4814 struct pool_workqueue
*pwq
;
4817 mutex_lock(&wq_pool_mutex
);
4819 WARN_ON_ONCE(workqueue_freezing
);
4820 workqueue_freezing
= true;
4823 for_each_pool(pool
, pi
) {
4824 spin_lock_irq(&pool
->lock
);
4825 WARN_ON_ONCE(pool
->flags
& POOL_FREEZING
);
4826 pool
->flags
|= POOL_FREEZING
;
4827 spin_unlock_irq(&pool
->lock
);
4830 list_for_each_entry(wq
, &workqueues
, list
) {
4831 mutex_lock(&wq
->mutex
);
4832 for_each_pwq(pwq
, wq
)
4833 pwq_adjust_max_active(pwq
);
4834 mutex_unlock(&wq
->mutex
);
4837 mutex_unlock(&wq_pool_mutex
);
4841 * freeze_workqueues_busy - are freezable workqueues still busy?
4843 * Check whether freezing is complete. This function must be called
4844 * between freeze_workqueues_begin() and thaw_workqueues().
4847 * Grabs and releases wq_pool_mutex.
4850 * %true if some freezable workqueues are still busy. %false if freezing
4853 bool freeze_workqueues_busy(void)
4856 struct workqueue_struct
*wq
;
4857 struct pool_workqueue
*pwq
;
4859 mutex_lock(&wq_pool_mutex
);
4861 WARN_ON_ONCE(!workqueue_freezing
);
4863 list_for_each_entry(wq
, &workqueues
, list
) {
4864 if (!(wq
->flags
& WQ_FREEZABLE
))
4867 * nr_active is monotonically decreasing. It's safe
4868 * to peek without lock.
4870 rcu_read_lock_sched();
4871 for_each_pwq(pwq
, wq
) {
4872 WARN_ON_ONCE(pwq
->nr_active
< 0);
4873 if (pwq
->nr_active
) {
4875 rcu_read_unlock_sched();
4879 rcu_read_unlock_sched();
4882 mutex_unlock(&wq_pool_mutex
);
4887 * thaw_workqueues - thaw workqueues
4889 * Thaw workqueues. Normal queueing is restored and all collected
4890 * frozen works are transferred to their respective pool worklists.
4893 * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's.
4895 void thaw_workqueues(void)
4897 struct workqueue_struct
*wq
;
4898 struct pool_workqueue
*pwq
;
4899 struct worker_pool
*pool
;
4902 mutex_lock(&wq_pool_mutex
);
4904 if (!workqueue_freezing
)
4907 /* clear FREEZING */
4908 for_each_pool(pool
, pi
) {
4909 spin_lock_irq(&pool
->lock
);
4910 WARN_ON_ONCE(!(pool
->flags
& POOL_FREEZING
));
4911 pool
->flags
&= ~POOL_FREEZING
;
4912 spin_unlock_irq(&pool
->lock
);
4915 /* restore max_active and repopulate worklist */
4916 list_for_each_entry(wq
, &workqueues
, list
) {
4917 mutex_lock(&wq
->mutex
);
4918 for_each_pwq(pwq
, wq
)
4919 pwq_adjust_max_active(pwq
);
4920 mutex_unlock(&wq
->mutex
);
4923 workqueue_freezing
= false;
4925 mutex_unlock(&wq_pool_mutex
);
4927 #endif /* CONFIG_FREEZER */
4929 static void __init
wq_numa_init(void)
4934 /* determine NUMA pwq table len - highest node id + 1 */
4936 wq_numa_tbl_len
= max(wq_numa_tbl_len
, node
+ 1);
4938 if (num_possible_nodes() <= 1)
4941 if (wq_disable_numa
) {
4942 pr_info("workqueue: NUMA affinity support disabled\n");
4946 wq_update_unbound_numa_attrs_buf
= alloc_workqueue_attrs(GFP_KERNEL
);
4947 BUG_ON(!wq_update_unbound_numa_attrs_buf
);
4950 * We want masks of possible CPUs of each node which isn't readily
4951 * available. Build one from cpu_to_node() which should have been
4952 * fully initialized by now.
4954 tbl
= kzalloc(wq_numa_tbl_len
* sizeof(tbl
[0]), GFP_KERNEL
);
4958 BUG_ON(!alloc_cpumask_var_node(&tbl
[node
], GFP_KERNEL
,
4959 node_online(node
) ? node
: NUMA_NO_NODE
));
4961 for_each_possible_cpu(cpu
) {
4962 node
= cpu_to_node(cpu
);
4963 if (WARN_ON(node
== NUMA_NO_NODE
)) {
4964 pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu
);
4965 /* happens iff arch is bonkers, let's just proceed */
4968 cpumask_set_cpu(cpu
, tbl
[node
]);
4971 wq_numa_possible_cpumask
= tbl
;
4972 wq_numa_enabled
= true;
4975 static int __init
init_workqueues(void)
4977 int std_nice
[NR_STD_WORKER_POOLS
] = { 0, HIGHPRI_NICE_LEVEL
};
4980 /* make sure we have enough bits for OFFQ pool ID */
4981 BUILD_BUG_ON((1LU << (BITS_PER_LONG
- WORK_OFFQ_POOL_SHIFT
)) <
4982 WORK_CPU_END
* NR_STD_WORKER_POOLS
);
4984 WARN_ON(__alignof__(struct pool_workqueue
) < __alignof__(long long));
4986 pwq_cache
= KMEM_CACHE(pool_workqueue
, SLAB_PANIC
);
4988 cpu_notifier(workqueue_cpu_up_callback
, CPU_PRI_WORKQUEUE_UP
);
4989 hotcpu_notifier(workqueue_cpu_down_callback
, CPU_PRI_WORKQUEUE_DOWN
);
4993 /* initialize CPU pools */
4994 for_each_possible_cpu(cpu
) {
4995 struct worker_pool
*pool
;
4998 for_each_cpu_worker_pool(pool
, cpu
) {
4999 BUG_ON(init_worker_pool(pool
));
5001 cpumask_copy(pool
->attrs
->cpumask
, cpumask_of(cpu
));
5002 pool
->attrs
->nice
= std_nice
[i
++];
5003 pool
->node
= cpu_to_node(cpu
);
5006 mutex_lock(&wq_pool_mutex
);
5007 BUG_ON(worker_pool_assign_id(pool
));
5008 mutex_unlock(&wq_pool_mutex
);
5012 /* create the initial worker */
5013 for_each_online_cpu(cpu
) {
5014 struct worker_pool
*pool
;
5016 for_each_cpu_worker_pool(pool
, cpu
) {
5017 pool
->flags
&= ~POOL_DISASSOCIATED
;
5018 BUG_ON(create_and_start_worker(pool
) < 0);
5022 /* create default unbound wq attrs */
5023 for (i
= 0; i
< NR_STD_WORKER_POOLS
; i
++) {
5024 struct workqueue_attrs
*attrs
;
5026 BUG_ON(!(attrs
= alloc_workqueue_attrs(GFP_KERNEL
)));
5027 attrs
->nice
= std_nice
[i
];
5028 unbound_std_wq_attrs
[i
] = attrs
;
5031 system_wq
= alloc_workqueue("events", 0, 0);
5032 system_highpri_wq
= alloc_workqueue("events_highpri", WQ_HIGHPRI
, 0);
5033 system_long_wq
= alloc_workqueue("events_long", 0, 0);
5034 system_unbound_wq
= alloc_workqueue("events_unbound", WQ_UNBOUND
,
5035 WQ_UNBOUND_MAX_ACTIVE
);
5036 system_freezable_wq
= alloc_workqueue("events_freezable",
5038 system_power_efficient_wq
= alloc_workqueue("events_power_efficient",
5039 WQ_POWER_EFFICIENT
, 0);
5040 system_freezable_power_efficient_wq
= alloc_workqueue("events_freezable_power_efficient",
5041 WQ_FREEZABLE
| WQ_POWER_EFFICIENT
,
5043 BUG_ON(!system_wq
|| !system_highpri_wq
|| !system_long_wq
||
5044 !system_unbound_wq
|| !system_freezable_wq
||
5045 !system_power_efficient_wq
||
5046 !system_freezable_power_efficient_wq
);
5049 early_initcall(init_workqueues
);