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1da177e4 LT |
1 | /* |
2 | * linux/kernel/workqueue.c | |
3 | * | |
4 | * Generic mechanism for defining kernel helper threads for running | |
5 | * arbitrary tasks in process context. | |
6 | * | |
7 | * Started by Ingo Molnar, Copyright (C) 2002 | |
8 | * | |
9 | * Derived from the taskqueue/keventd code by: | |
10 | * | |
11 | * David Woodhouse <dwmw2@infradead.org> | |
e1f8e874 | 12 | * Andrew Morton |
1da177e4 LT |
13 | * Kai Petzke <wpp@marie.physik.tu-berlin.de> |
14 | * Theodore Ts'o <tytso@mit.edu> | |
89ada679 | 15 | * |
cde53535 | 16 | * Made to use alloc_percpu by Christoph Lameter. |
1da177e4 LT |
17 | */ |
18 | ||
19 | #include <linux/module.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/sched.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/signal.h> | |
24 | #include <linux/completion.h> | |
25 | #include <linux/workqueue.h> | |
26 | #include <linux/slab.h> | |
27 | #include <linux/cpu.h> | |
28 | #include <linux/notifier.h> | |
29 | #include <linux/kthread.h> | |
1fa44eca | 30 | #include <linux/hardirq.h> |
46934023 | 31 | #include <linux/mempolicy.h> |
341a5958 | 32 | #include <linux/freezer.h> |
d5abe669 PZ |
33 | #include <linux/kallsyms.h> |
34 | #include <linux/debug_locks.h> | |
4e6045f1 | 35 | #include <linux/lockdep.h> |
1da177e4 | 36 | |
4690c4ab TH |
37 | /* |
38 | * Structure fields follow one of the following exclusion rules. | |
39 | * | |
40 | * I: Set during initialization and read-only afterwards. | |
41 | * | |
42 | * L: cwq->lock protected. Access with cwq->lock held. | |
43 | * | |
44 | * W: workqueue_lock protected. | |
45 | */ | |
46 | ||
1da177e4 | 47 | /* |
f756d5e2 NL |
48 | * The per-CPU workqueue (if single thread, we always use the first |
49 | * possible cpu). | |
1da177e4 LT |
50 | */ |
51 | struct cpu_workqueue_struct { | |
52 | ||
53 | spinlock_t lock; | |
54 | ||
1da177e4 LT |
55 | struct list_head worklist; |
56 | wait_queue_head_t more_work; | |
3af24433 | 57 | struct work_struct *current_work; |
1537663f | 58 | unsigned int cpu; |
1da177e4 | 59 | |
4690c4ab TH |
60 | struct workqueue_struct *wq; /* I: the owning workqueue */ |
61 | struct task_struct *thread; | |
1da177e4 LT |
62 | } ____cacheline_aligned; |
63 | ||
64 | /* | |
65 | * The externally visible workqueue abstraction is an array of | |
66 | * per-CPU workqueues: | |
67 | */ | |
68 | struct workqueue_struct { | |
97e37d7b | 69 | unsigned int flags; /* I: WQ_* flags */ |
4690c4ab TH |
70 | struct cpu_workqueue_struct *cpu_wq; /* I: cwq's */ |
71 | struct list_head list; /* W: list of all workqueues */ | |
72 | const char *name; /* I: workqueue name */ | |
4e6045f1 | 73 | #ifdef CONFIG_LOCKDEP |
4690c4ab | 74 | struct lockdep_map lockdep_map; |
4e6045f1 | 75 | #endif |
1da177e4 LT |
76 | }; |
77 | ||
dc186ad7 TG |
78 | #ifdef CONFIG_DEBUG_OBJECTS_WORK |
79 | ||
80 | static struct debug_obj_descr work_debug_descr; | |
81 | ||
82 | /* | |
83 | * fixup_init is called when: | |
84 | * - an active object is initialized | |
85 | */ | |
86 | static int work_fixup_init(void *addr, enum debug_obj_state state) | |
87 | { | |
88 | struct work_struct *work = addr; | |
89 | ||
90 | switch (state) { | |
91 | case ODEBUG_STATE_ACTIVE: | |
92 | cancel_work_sync(work); | |
93 | debug_object_init(work, &work_debug_descr); | |
94 | return 1; | |
95 | default: | |
96 | return 0; | |
97 | } | |
98 | } | |
99 | ||
100 | /* | |
101 | * fixup_activate is called when: | |
102 | * - an active object is activated | |
103 | * - an unknown object is activated (might be a statically initialized object) | |
104 | */ | |
105 | static int work_fixup_activate(void *addr, enum debug_obj_state state) | |
106 | { | |
107 | struct work_struct *work = addr; | |
108 | ||
109 | switch (state) { | |
110 | ||
111 | case ODEBUG_STATE_NOTAVAILABLE: | |
112 | /* | |
113 | * This is not really a fixup. The work struct was | |
114 | * statically initialized. We just make sure that it | |
115 | * is tracked in the object tracker. | |
116 | */ | |
22df02bb | 117 | if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
dc186ad7 TG |
118 | debug_object_init(work, &work_debug_descr); |
119 | debug_object_activate(work, &work_debug_descr); | |
120 | return 0; | |
121 | } | |
122 | WARN_ON_ONCE(1); | |
123 | return 0; | |
124 | ||
125 | case ODEBUG_STATE_ACTIVE: | |
126 | WARN_ON(1); | |
127 | ||
128 | default: | |
129 | return 0; | |
130 | } | |
131 | } | |
132 | ||
133 | /* | |
134 | * fixup_free is called when: | |
135 | * - an active object is freed | |
136 | */ | |
137 | static int work_fixup_free(void *addr, enum debug_obj_state state) | |
138 | { | |
139 | struct work_struct *work = addr; | |
140 | ||
141 | switch (state) { | |
142 | case ODEBUG_STATE_ACTIVE: | |
143 | cancel_work_sync(work); | |
144 | debug_object_free(work, &work_debug_descr); | |
145 | return 1; | |
146 | default: | |
147 | return 0; | |
148 | } | |
149 | } | |
150 | ||
151 | static struct debug_obj_descr work_debug_descr = { | |
152 | .name = "work_struct", | |
153 | .fixup_init = work_fixup_init, | |
154 | .fixup_activate = work_fixup_activate, | |
155 | .fixup_free = work_fixup_free, | |
156 | }; | |
157 | ||
158 | static inline void debug_work_activate(struct work_struct *work) | |
159 | { | |
160 | debug_object_activate(work, &work_debug_descr); | |
161 | } | |
162 | ||
163 | static inline void debug_work_deactivate(struct work_struct *work) | |
164 | { | |
165 | debug_object_deactivate(work, &work_debug_descr); | |
166 | } | |
167 | ||
168 | void __init_work(struct work_struct *work, int onstack) | |
169 | { | |
170 | if (onstack) | |
171 | debug_object_init_on_stack(work, &work_debug_descr); | |
172 | else | |
173 | debug_object_init(work, &work_debug_descr); | |
174 | } | |
175 | EXPORT_SYMBOL_GPL(__init_work); | |
176 | ||
177 | void destroy_work_on_stack(struct work_struct *work) | |
178 | { | |
179 | debug_object_free(work, &work_debug_descr); | |
180 | } | |
181 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); | |
182 | ||
183 | #else | |
184 | static inline void debug_work_activate(struct work_struct *work) { } | |
185 | static inline void debug_work_deactivate(struct work_struct *work) { } | |
186 | #endif | |
187 | ||
95402b38 GS |
188 | /* Serializes the accesses to the list of workqueues. */ |
189 | static DEFINE_SPINLOCK(workqueue_lock); | |
1da177e4 LT |
190 | static LIST_HEAD(workqueues); |
191 | ||
3af24433 | 192 | static int singlethread_cpu __read_mostly; |
1da177e4 | 193 | |
1537663f TH |
194 | static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, |
195 | struct workqueue_struct *wq) | |
b1f4ec17 | 196 | { |
1537663f | 197 | return per_cpu_ptr(wq->cpu_wq, cpu); |
b1f4ec17 ON |
198 | } |
199 | ||
1537663f TH |
200 | static struct cpu_workqueue_struct *target_cwq(unsigned int cpu, |
201 | struct workqueue_struct *wq) | |
a848e3b6 | 202 | { |
1537663f | 203 | if (unlikely(wq->flags & WQ_SINGLE_THREAD)) |
a848e3b6 | 204 | cpu = singlethread_cpu; |
1537663f | 205 | return get_cwq(cpu, wq); |
a848e3b6 ON |
206 | } |
207 | ||
4594bf15 DH |
208 | /* |
209 | * Set the workqueue on which a work item is to be run | |
210 | * - Must *only* be called if the pending flag is set | |
211 | */ | |
ed7c0fee | 212 | static inline void set_wq_data(struct work_struct *work, |
4690c4ab TH |
213 | struct cpu_workqueue_struct *cwq, |
214 | unsigned long extra_flags) | |
365970a1 | 215 | { |
4594bf15 | 216 | BUG_ON(!work_pending(work)); |
365970a1 | 217 | |
4690c4ab | 218 | atomic_long_set(&work->data, (unsigned long)cwq | work_static(work) | |
22df02bb | 219 | WORK_STRUCT_PENDING | extra_flags); |
365970a1 DH |
220 | } |
221 | ||
4d707b9f ON |
222 | /* |
223 | * Clear WORK_STRUCT_PENDING and the workqueue on which it was queued. | |
224 | */ | |
225 | static inline void clear_wq_data(struct work_struct *work) | |
226 | { | |
4690c4ab | 227 | atomic_long_set(&work->data, work_static(work)); |
4d707b9f ON |
228 | } |
229 | ||
64166699 | 230 | static inline struct cpu_workqueue_struct *get_wq_data(struct work_struct *work) |
365970a1 | 231 | { |
64166699 TH |
232 | return (void *)(atomic_long_read(&work->data) & |
233 | WORK_STRUCT_WQ_DATA_MASK); | |
365970a1 DH |
234 | } |
235 | ||
4690c4ab TH |
236 | /** |
237 | * insert_work - insert a work into cwq | |
238 | * @cwq: cwq @work belongs to | |
239 | * @work: work to insert | |
240 | * @head: insertion point | |
241 | * @extra_flags: extra WORK_STRUCT_* flags to set | |
242 | * | |
243 | * Insert @work into @cwq after @head. | |
244 | * | |
245 | * CONTEXT: | |
246 | * spin_lock_irq(cwq->lock). | |
247 | */ | |
b89deed3 | 248 | static void insert_work(struct cpu_workqueue_struct *cwq, |
4690c4ab TH |
249 | struct work_struct *work, struct list_head *head, |
250 | unsigned int extra_flags) | |
b89deed3 | 251 | { |
4690c4ab TH |
252 | /* we own @work, set data and link */ |
253 | set_wq_data(work, cwq, extra_flags); | |
254 | ||
6e84d644 ON |
255 | /* |
256 | * Ensure that we get the right work->data if we see the | |
257 | * result of list_add() below, see try_to_grab_pending(). | |
258 | */ | |
259 | smp_wmb(); | |
4690c4ab | 260 | |
1a4d9b0a | 261 | list_add_tail(&work->entry, head); |
b89deed3 ON |
262 | wake_up(&cwq->more_work); |
263 | } | |
264 | ||
4690c4ab | 265 | static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, |
1da177e4 LT |
266 | struct work_struct *work) |
267 | { | |
1537663f | 268 | struct cpu_workqueue_struct *cwq = target_cwq(cpu, wq); |
1da177e4 LT |
269 | unsigned long flags; |
270 | ||
dc186ad7 | 271 | debug_work_activate(work); |
1da177e4 | 272 | spin_lock_irqsave(&cwq->lock, flags); |
4690c4ab TH |
273 | BUG_ON(!list_empty(&work->entry)); |
274 | insert_work(cwq, work, &cwq->worklist, 0); | |
1da177e4 LT |
275 | spin_unlock_irqrestore(&cwq->lock, flags); |
276 | } | |
277 | ||
0fcb78c2 REB |
278 | /** |
279 | * queue_work - queue work on a workqueue | |
280 | * @wq: workqueue to use | |
281 | * @work: work to queue | |
282 | * | |
057647fc | 283 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1da177e4 | 284 | * |
00dfcaf7 ON |
285 | * We queue the work to the CPU on which it was submitted, but if the CPU dies |
286 | * it can be processed by another CPU. | |
1da177e4 | 287 | */ |
7ad5b3a5 | 288 | int queue_work(struct workqueue_struct *wq, struct work_struct *work) |
1da177e4 | 289 | { |
ef1ca236 ON |
290 | int ret; |
291 | ||
292 | ret = queue_work_on(get_cpu(), wq, work); | |
293 | put_cpu(); | |
294 | ||
1da177e4 LT |
295 | return ret; |
296 | } | |
ae90dd5d | 297 | EXPORT_SYMBOL_GPL(queue_work); |
1da177e4 | 298 | |
c1a220e7 ZR |
299 | /** |
300 | * queue_work_on - queue work on specific cpu | |
301 | * @cpu: CPU number to execute work on | |
302 | * @wq: workqueue to use | |
303 | * @work: work to queue | |
304 | * | |
305 | * Returns 0 if @work was already on a queue, non-zero otherwise. | |
306 | * | |
307 | * We queue the work to a specific CPU, the caller must ensure it | |
308 | * can't go away. | |
309 | */ | |
310 | int | |
311 | queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) | |
312 | { | |
313 | int ret = 0; | |
314 | ||
22df02bb | 315 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
4690c4ab | 316 | __queue_work(cpu, wq, work); |
c1a220e7 ZR |
317 | ret = 1; |
318 | } | |
319 | return ret; | |
320 | } | |
321 | EXPORT_SYMBOL_GPL(queue_work_on); | |
322 | ||
6d141c3f | 323 | static void delayed_work_timer_fn(unsigned long __data) |
1da177e4 | 324 | { |
52bad64d | 325 | struct delayed_work *dwork = (struct delayed_work *)__data; |
ed7c0fee | 326 | struct cpu_workqueue_struct *cwq = get_wq_data(&dwork->work); |
1da177e4 | 327 | |
4690c4ab | 328 | __queue_work(smp_processor_id(), cwq->wq, &dwork->work); |
1da177e4 LT |
329 | } |
330 | ||
0fcb78c2 REB |
331 | /** |
332 | * queue_delayed_work - queue work on a workqueue after delay | |
333 | * @wq: workqueue to use | |
af9997e4 | 334 | * @dwork: delayable work to queue |
0fcb78c2 REB |
335 | * @delay: number of jiffies to wait before queueing |
336 | * | |
057647fc | 337 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
0fcb78c2 | 338 | */ |
7ad5b3a5 | 339 | int queue_delayed_work(struct workqueue_struct *wq, |
52bad64d | 340 | struct delayed_work *dwork, unsigned long delay) |
1da177e4 | 341 | { |
52bad64d | 342 | if (delay == 0) |
63bc0362 | 343 | return queue_work(wq, &dwork->work); |
1da177e4 | 344 | |
63bc0362 | 345 | return queue_delayed_work_on(-1, wq, dwork, delay); |
1da177e4 | 346 | } |
ae90dd5d | 347 | EXPORT_SYMBOL_GPL(queue_delayed_work); |
1da177e4 | 348 | |
0fcb78c2 REB |
349 | /** |
350 | * queue_delayed_work_on - queue work on specific CPU after delay | |
351 | * @cpu: CPU number to execute work on | |
352 | * @wq: workqueue to use | |
af9997e4 | 353 | * @dwork: work to queue |
0fcb78c2 REB |
354 | * @delay: number of jiffies to wait before queueing |
355 | * | |
057647fc | 356 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
0fcb78c2 | 357 | */ |
7a6bc1cd | 358 | int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
52bad64d | 359 | struct delayed_work *dwork, unsigned long delay) |
7a6bc1cd VP |
360 | { |
361 | int ret = 0; | |
52bad64d DH |
362 | struct timer_list *timer = &dwork->timer; |
363 | struct work_struct *work = &dwork->work; | |
7a6bc1cd | 364 | |
22df02bb | 365 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
7a6bc1cd VP |
366 | BUG_ON(timer_pending(timer)); |
367 | BUG_ON(!list_empty(&work->entry)); | |
368 | ||
8a3e77cc AL |
369 | timer_stats_timer_set_start_info(&dwork->timer); |
370 | ||
ed7c0fee | 371 | /* This stores cwq for the moment, for the timer_fn */ |
1537663f | 372 | set_wq_data(work, target_cwq(raw_smp_processor_id(), wq), 0); |
7a6bc1cd | 373 | timer->expires = jiffies + delay; |
52bad64d | 374 | timer->data = (unsigned long)dwork; |
7a6bc1cd | 375 | timer->function = delayed_work_timer_fn; |
63bc0362 ON |
376 | |
377 | if (unlikely(cpu >= 0)) | |
378 | add_timer_on(timer, cpu); | |
379 | else | |
380 | add_timer(timer); | |
7a6bc1cd VP |
381 | ret = 1; |
382 | } | |
383 | return ret; | |
384 | } | |
ae90dd5d | 385 | EXPORT_SYMBOL_GPL(queue_delayed_work_on); |
1da177e4 | 386 | |
a62428c0 TH |
387 | /** |
388 | * process_one_work - process single work | |
389 | * @cwq: cwq to process work for | |
390 | * @work: work to process | |
391 | * | |
392 | * Process @work. This function contains all the logics necessary to | |
393 | * process a single work including synchronization against and | |
394 | * interaction with other workers on the same cpu, queueing and | |
395 | * flushing. As long as context requirement is met, any worker can | |
396 | * call this function to process a work. | |
397 | * | |
398 | * CONTEXT: | |
399 | * spin_lock_irq(cwq->lock) which is released and regrabbed. | |
400 | */ | |
401 | static void process_one_work(struct cpu_workqueue_struct *cwq, | |
402 | struct work_struct *work) | |
403 | { | |
404 | work_func_t f = work->func; | |
405 | #ifdef CONFIG_LOCKDEP | |
406 | /* | |
407 | * It is permissible to free the struct work_struct from | |
408 | * inside the function that is called from it, this we need to | |
409 | * take into account for lockdep too. To avoid bogus "held | |
410 | * lock freed" warnings as well as problems when looking into | |
411 | * work->lockdep_map, make a copy and use that here. | |
412 | */ | |
413 | struct lockdep_map lockdep_map = work->lockdep_map; | |
414 | #endif | |
415 | /* claim and process */ | |
a62428c0 TH |
416 | debug_work_deactivate(work); |
417 | cwq->current_work = work; | |
418 | list_del_init(&work->entry); | |
419 | ||
420 | spin_unlock_irq(&cwq->lock); | |
421 | ||
422 | BUG_ON(get_wq_data(work) != cwq); | |
423 | work_clear_pending(work); | |
424 | lock_map_acquire(&cwq->wq->lockdep_map); | |
425 | lock_map_acquire(&lockdep_map); | |
426 | f(work); | |
427 | lock_map_release(&lockdep_map); | |
428 | lock_map_release(&cwq->wq->lockdep_map); | |
429 | ||
430 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { | |
431 | printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " | |
432 | "%s/0x%08x/%d\n", | |
433 | current->comm, preempt_count(), task_pid_nr(current)); | |
434 | printk(KERN_ERR " last function: "); | |
435 | print_symbol("%s\n", (unsigned long)f); | |
436 | debug_show_held_locks(current); | |
437 | dump_stack(); | |
438 | } | |
439 | ||
440 | spin_lock_irq(&cwq->lock); | |
441 | ||
442 | /* we're done with it, release */ | |
443 | cwq->current_work = NULL; | |
444 | } | |
445 | ||
858119e1 | 446 | static void run_workqueue(struct cpu_workqueue_struct *cwq) |
1da177e4 | 447 | { |
f293ea92 | 448 | spin_lock_irq(&cwq->lock); |
1da177e4 LT |
449 | while (!list_empty(&cwq->worklist)) { |
450 | struct work_struct *work = list_entry(cwq->worklist.next, | |
451 | struct work_struct, entry); | |
a62428c0 | 452 | process_one_work(cwq, work); |
1da177e4 | 453 | } |
f293ea92 | 454 | spin_unlock_irq(&cwq->lock); |
1da177e4 LT |
455 | } |
456 | ||
4690c4ab TH |
457 | /** |
458 | * worker_thread - the worker thread function | |
459 | * @__cwq: cwq to serve | |
460 | * | |
461 | * The cwq worker thread function. | |
462 | */ | |
1da177e4 LT |
463 | static int worker_thread(void *__cwq) |
464 | { | |
465 | struct cpu_workqueue_struct *cwq = __cwq; | |
3af24433 | 466 | DEFINE_WAIT(wait); |
1da177e4 | 467 | |
97e37d7b | 468 | if (cwq->wq->flags & WQ_FREEZEABLE) |
83144186 | 469 | set_freezable(); |
1da177e4 | 470 | |
3af24433 | 471 | for (;;) { |
3af24433 | 472 | prepare_to_wait(&cwq->more_work, &wait, TASK_INTERRUPTIBLE); |
14441960 ON |
473 | if (!freezing(current) && |
474 | !kthread_should_stop() && | |
475 | list_empty(&cwq->worklist)) | |
1da177e4 | 476 | schedule(); |
3af24433 ON |
477 | finish_wait(&cwq->more_work, &wait); |
478 | ||
85f4186a ON |
479 | try_to_freeze(); |
480 | ||
14441960 | 481 | if (kthread_should_stop()) |
3af24433 | 482 | break; |
1da177e4 | 483 | |
1537663f TH |
484 | if (unlikely(!cpumask_equal(&cwq->thread->cpus_allowed, |
485 | get_cpu_mask(cwq->cpu)))) | |
486 | set_cpus_allowed_ptr(cwq->thread, | |
487 | get_cpu_mask(cwq->cpu)); | |
3af24433 | 488 | run_workqueue(cwq); |
1da177e4 | 489 | } |
3af24433 | 490 | |
1da177e4 LT |
491 | return 0; |
492 | } | |
493 | ||
fc2e4d70 ON |
494 | struct wq_barrier { |
495 | struct work_struct work; | |
496 | struct completion done; | |
497 | }; | |
498 | ||
499 | static void wq_barrier_func(struct work_struct *work) | |
500 | { | |
501 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); | |
502 | complete(&barr->done); | |
503 | } | |
504 | ||
4690c4ab TH |
505 | /** |
506 | * insert_wq_barrier - insert a barrier work | |
507 | * @cwq: cwq to insert barrier into | |
508 | * @barr: wq_barrier to insert | |
509 | * @head: insertion point | |
510 | * | |
511 | * Insert barrier @barr into @cwq before @head. | |
512 | * | |
513 | * CONTEXT: | |
514 | * spin_lock_irq(cwq->lock). | |
515 | */ | |
83c22520 | 516 | static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, |
1a4d9b0a | 517 | struct wq_barrier *barr, struct list_head *head) |
fc2e4d70 | 518 | { |
dc186ad7 TG |
519 | /* |
520 | * debugobject calls are safe here even with cwq->lock locked | |
521 | * as we know for sure that this will not trigger any of the | |
522 | * checks and call back into the fixup functions where we | |
523 | * might deadlock. | |
524 | */ | |
525 | INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); | |
22df02bb | 526 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
fc2e4d70 | 527 | init_completion(&barr->done); |
83c22520 | 528 | |
dc186ad7 | 529 | debug_work_activate(&barr->work); |
4690c4ab | 530 | insert_work(cwq, &barr->work, head, 0); |
fc2e4d70 ON |
531 | } |
532 | ||
14441960 | 533 | static int flush_cpu_workqueue(struct cpu_workqueue_struct *cwq) |
1da177e4 | 534 | { |
2355b70f LJ |
535 | int active = 0; |
536 | struct wq_barrier barr; | |
1da177e4 | 537 | |
2355b70f | 538 | WARN_ON(cwq->thread == current); |
1da177e4 | 539 | |
2355b70f LJ |
540 | spin_lock_irq(&cwq->lock); |
541 | if (!list_empty(&cwq->worklist) || cwq->current_work != NULL) { | |
542 | insert_wq_barrier(cwq, &barr, &cwq->worklist); | |
543 | active = 1; | |
1da177e4 | 544 | } |
2355b70f LJ |
545 | spin_unlock_irq(&cwq->lock); |
546 | ||
dc186ad7 | 547 | if (active) { |
2355b70f | 548 | wait_for_completion(&barr.done); |
dc186ad7 TG |
549 | destroy_work_on_stack(&barr.work); |
550 | } | |
14441960 ON |
551 | |
552 | return active; | |
1da177e4 LT |
553 | } |
554 | ||
0fcb78c2 | 555 | /** |
1da177e4 | 556 | * flush_workqueue - ensure that any scheduled work has run to completion. |
0fcb78c2 | 557 | * @wq: workqueue to flush |
1da177e4 LT |
558 | * |
559 | * Forces execution of the workqueue and blocks until its completion. | |
560 | * This is typically used in driver shutdown handlers. | |
561 | * | |
fc2e4d70 ON |
562 | * We sleep until all works which were queued on entry have been handled, |
563 | * but we are not livelocked by new incoming ones. | |
1da177e4 | 564 | */ |
7ad5b3a5 | 565 | void flush_workqueue(struct workqueue_struct *wq) |
1da177e4 | 566 | { |
cce1a165 | 567 | int cpu; |
1da177e4 | 568 | |
b1f4ec17 | 569 | might_sleep(); |
3295f0ef IM |
570 | lock_map_acquire(&wq->lockdep_map); |
571 | lock_map_release(&wq->lockdep_map); | |
1537663f TH |
572 | for_each_possible_cpu(cpu) |
573 | flush_cpu_workqueue(get_cwq(cpu, wq)); | |
1da177e4 | 574 | } |
ae90dd5d | 575 | EXPORT_SYMBOL_GPL(flush_workqueue); |
1da177e4 | 576 | |
db700897 ON |
577 | /** |
578 | * flush_work - block until a work_struct's callback has terminated | |
579 | * @work: the work which is to be flushed | |
580 | * | |
a67da70d ON |
581 | * Returns false if @work has already terminated. |
582 | * | |
db700897 ON |
583 | * It is expected that, prior to calling flush_work(), the caller has |
584 | * arranged for the work to not be requeued, otherwise it doesn't make | |
585 | * sense to use this function. | |
586 | */ | |
587 | int flush_work(struct work_struct *work) | |
588 | { | |
589 | struct cpu_workqueue_struct *cwq; | |
590 | struct list_head *prev; | |
591 | struct wq_barrier barr; | |
592 | ||
593 | might_sleep(); | |
594 | cwq = get_wq_data(work); | |
595 | if (!cwq) | |
596 | return 0; | |
597 | ||
3295f0ef IM |
598 | lock_map_acquire(&cwq->wq->lockdep_map); |
599 | lock_map_release(&cwq->wq->lockdep_map); | |
a67da70d | 600 | |
db700897 ON |
601 | spin_lock_irq(&cwq->lock); |
602 | if (!list_empty(&work->entry)) { | |
603 | /* | |
604 | * See the comment near try_to_grab_pending()->smp_rmb(). | |
605 | * If it was re-queued under us we are not going to wait. | |
606 | */ | |
607 | smp_rmb(); | |
608 | if (unlikely(cwq != get_wq_data(work))) | |
4690c4ab | 609 | goto already_gone; |
db700897 ON |
610 | prev = &work->entry; |
611 | } else { | |
612 | if (cwq->current_work != work) | |
4690c4ab | 613 | goto already_gone; |
db700897 ON |
614 | prev = &cwq->worklist; |
615 | } | |
616 | insert_wq_barrier(cwq, &barr, prev->next); | |
db700897 | 617 | |
4690c4ab | 618 | spin_unlock_irq(&cwq->lock); |
db700897 | 619 | wait_for_completion(&barr.done); |
dc186ad7 | 620 | destroy_work_on_stack(&barr.work); |
db700897 | 621 | return 1; |
4690c4ab TH |
622 | already_gone: |
623 | spin_unlock_irq(&cwq->lock); | |
624 | return 0; | |
db700897 ON |
625 | } |
626 | EXPORT_SYMBOL_GPL(flush_work); | |
627 | ||
6e84d644 | 628 | /* |
1f1f642e | 629 | * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, |
6e84d644 ON |
630 | * so this work can't be re-armed in any way. |
631 | */ | |
632 | static int try_to_grab_pending(struct work_struct *work) | |
633 | { | |
634 | struct cpu_workqueue_struct *cwq; | |
1f1f642e | 635 | int ret = -1; |
6e84d644 | 636 | |
22df02bb | 637 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
1f1f642e | 638 | return 0; |
6e84d644 ON |
639 | |
640 | /* | |
641 | * The queueing is in progress, or it is already queued. Try to | |
642 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. | |
643 | */ | |
644 | ||
645 | cwq = get_wq_data(work); | |
646 | if (!cwq) | |
647 | return ret; | |
648 | ||
649 | spin_lock_irq(&cwq->lock); | |
650 | if (!list_empty(&work->entry)) { | |
651 | /* | |
652 | * This work is queued, but perhaps we locked the wrong cwq. | |
653 | * In that case we must see the new value after rmb(), see | |
654 | * insert_work()->wmb(). | |
655 | */ | |
656 | smp_rmb(); | |
657 | if (cwq == get_wq_data(work)) { | |
dc186ad7 | 658 | debug_work_deactivate(work); |
6e84d644 ON |
659 | list_del_init(&work->entry); |
660 | ret = 1; | |
661 | } | |
662 | } | |
663 | spin_unlock_irq(&cwq->lock); | |
664 | ||
665 | return ret; | |
666 | } | |
667 | ||
668 | static void wait_on_cpu_work(struct cpu_workqueue_struct *cwq, | |
b89deed3 ON |
669 | struct work_struct *work) |
670 | { | |
671 | struct wq_barrier barr; | |
672 | int running = 0; | |
673 | ||
674 | spin_lock_irq(&cwq->lock); | |
675 | if (unlikely(cwq->current_work == work)) { | |
1a4d9b0a | 676 | insert_wq_barrier(cwq, &barr, cwq->worklist.next); |
b89deed3 ON |
677 | running = 1; |
678 | } | |
679 | spin_unlock_irq(&cwq->lock); | |
680 | ||
dc186ad7 | 681 | if (unlikely(running)) { |
b89deed3 | 682 | wait_for_completion(&barr.done); |
dc186ad7 TG |
683 | destroy_work_on_stack(&barr.work); |
684 | } | |
b89deed3 ON |
685 | } |
686 | ||
6e84d644 | 687 | static void wait_on_work(struct work_struct *work) |
b89deed3 ON |
688 | { |
689 | struct cpu_workqueue_struct *cwq; | |
28e53bdd | 690 | struct workqueue_struct *wq; |
b1f4ec17 | 691 | int cpu; |
b89deed3 | 692 | |
f293ea92 ON |
693 | might_sleep(); |
694 | ||
3295f0ef IM |
695 | lock_map_acquire(&work->lockdep_map); |
696 | lock_map_release(&work->lockdep_map); | |
4e6045f1 | 697 | |
b89deed3 | 698 | cwq = get_wq_data(work); |
b89deed3 | 699 | if (!cwq) |
3af24433 | 700 | return; |
b89deed3 | 701 | |
28e53bdd | 702 | wq = cwq->wq; |
28e53bdd | 703 | |
1537663f | 704 | for_each_possible_cpu(cpu) |
4690c4ab | 705 | wait_on_cpu_work(get_cwq(cpu, wq), work); |
6e84d644 ON |
706 | } |
707 | ||
1f1f642e ON |
708 | static int __cancel_work_timer(struct work_struct *work, |
709 | struct timer_list* timer) | |
710 | { | |
711 | int ret; | |
712 | ||
713 | do { | |
714 | ret = (timer && likely(del_timer(timer))); | |
715 | if (!ret) | |
716 | ret = try_to_grab_pending(work); | |
717 | wait_on_work(work); | |
718 | } while (unlikely(ret < 0)); | |
719 | ||
4d707b9f | 720 | clear_wq_data(work); |
1f1f642e ON |
721 | return ret; |
722 | } | |
723 | ||
6e84d644 ON |
724 | /** |
725 | * cancel_work_sync - block until a work_struct's callback has terminated | |
726 | * @work: the work which is to be flushed | |
727 | * | |
1f1f642e ON |
728 | * Returns true if @work was pending. |
729 | * | |
6e84d644 ON |
730 | * cancel_work_sync() will cancel the work if it is queued. If the work's |
731 | * callback appears to be running, cancel_work_sync() will block until it | |
732 | * has completed. | |
733 | * | |
734 | * It is possible to use this function if the work re-queues itself. It can | |
735 | * cancel the work even if it migrates to another workqueue, however in that | |
736 | * case it only guarantees that work->func() has completed on the last queued | |
737 | * workqueue. | |
738 | * | |
739 | * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not | |
740 | * pending, otherwise it goes into a busy-wait loop until the timer expires. | |
741 | * | |
742 | * The caller must ensure that workqueue_struct on which this work was last | |
743 | * queued can't be destroyed before this function returns. | |
744 | */ | |
1f1f642e | 745 | int cancel_work_sync(struct work_struct *work) |
6e84d644 | 746 | { |
1f1f642e | 747 | return __cancel_work_timer(work, NULL); |
b89deed3 | 748 | } |
28e53bdd | 749 | EXPORT_SYMBOL_GPL(cancel_work_sync); |
b89deed3 | 750 | |
6e84d644 | 751 | /** |
f5a421a4 | 752 | * cancel_delayed_work_sync - reliably kill off a delayed work. |
6e84d644 ON |
753 | * @dwork: the delayed work struct |
754 | * | |
1f1f642e ON |
755 | * Returns true if @dwork was pending. |
756 | * | |
6e84d644 ON |
757 | * It is possible to use this function if @dwork rearms itself via queue_work() |
758 | * or queue_delayed_work(). See also the comment for cancel_work_sync(). | |
759 | */ | |
1f1f642e | 760 | int cancel_delayed_work_sync(struct delayed_work *dwork) |
6e84d644 | 761 | { |
1f1f642e | 762 | return __cancel_work_timer(&dwork->work, &dwork->timer); |
6e84d644 | 763 | } |
f5a421a4 | 764 | EXPORT_SYMBOL(cancel_delayed_work_sync); |
1da177e4 | 765 | |
6e84d644 | 766 | static struct workqueue_struct *keventd_wq __read_mostly; |
1da177e4 | 767 | |
0fcb78c2 REB |
768 | /** |
769 | * schedule_work - put work task in global workqueue | |
770 | * @work: job to be done | |
771 | * | |
5b0f437d BVA |
772 | * Returns zero if @work was already on the kernel-global workqueue and |
773 | * non-zero otherwise. | |
774 | * | |
775 | * This puts a job in the kernel-global workqueue if it was not already | |
776 | * queued and leaves it in the same position on the kernel-global | |
777 | * workqueue otherwise. | |
0fcb78c2 | 778 | */ |
7ad5b3a5 | 779 | int schedule_work(struct work_struct *work) |
1da177e4 LT |
780 | { |
781 | return queue_work(keventd_wq, work); | |
782 | } | |
ae90dd5d | 783 | EXPORT_SYMBOL(schedule_work); |
1da177e4 | 784 | |
c1a220e7 ZR |
785 | /* |
786 | * schedule_work_on - put work task on a specific cpu | |
787 | * @cpu: cpu to put the work task on | |
788 | * @work: job to be done | |
789 | * | |
790 | * This puts a job on a specific cpu | |
791 | */ | |
792 | int schedule_work_on(int cpu, struct work_struct *work) | |
793 | { | |
794 | return queue_work_on(cpu, keventd_wq, work); | |
795 | } | |
796 | EXPORT_SYMBOL(schedule_work_on); | |
797 | ||
0fcb78c2 REB |
798 | /** |
799 | * schedule_delayed_work - put work task in global workqueue after delay | |
52bad64d DH |
800 | * @dwork: job to be done |
801 | * @delay: number of jiffies to wait or 0 for immediate execution | |
0fcb78c2 REB |
802 | * |
803 | * After waiting for a given time this puts a job in the kernel-global | |
804 | * workqueue. | |
805 | */ | |
7ad5b3a5 | 806 | int schedule_delayed_work(struct delayed_work *dwork, |
82f67cd9 | 807 | unsigned long delay) |
1da177e4 | 808 | { |
52bad64d | 809 | return queue_delayed_work(keventd_wq, dwork, delay); |
1da177e4 | 810 | } |
ae90dd5d | 811 | EXPORT_SYMBOL(schedule_delayed_work); |
1da177e4 | 812 | |
8c53e463 LT |
813 | /** |
814 | * flush_delayed_work - block until a dwork_struct's callback has terminated | |
815 | * @dwork: the delayed work which is to be flushed | |
816 | * | |
817 | * Any timeout is cancelled, and any pending work is run immediately. | |
818 | */ | |
819 | void flush_delayed_work(struct delayed_work *dwork) | |
820 | { | |
821 | if (del_timer_sync(&dwork->timer)) { | |
4690c4ab TH |
822 | __queue_work(get_cpu(), get_wq_data(&dwork->work)->wq, |
823 | &dwork->work); | |
8c53e463 LT |
824 | put_cpu(); |
825 | } | |
826 | flush_work(&dwork->work); | |
827 | } | |
828 | EXPORT_SYMBOL(flush_delayed_work); | |
829 | ||
0fcb78c2 REB |
830 | /** |
831 | * schedule_delayed_work_on - queue work in global workqueue on CPU after delay | |
832 | * @cpu: cpu to use | |
52bad64d | 833 | * @dwork: job to be done |
0fcb78c2 REB |
834 | * @delay: number of jiffies to wait |
835 | * | |
836 | * After waiting for a given time this puts a job in the kernel-global | |
837 | * workqueue on the specified CPU. | |
838 | */ | |
1da177e4 | 839 | int schedule_delayed_work_on(int cpu, |
52bad64d | 840 | struct delayed_work *dwork, unsigned long delay) |
1da177e4 | 841 | { |
52bad64d | 842 | return queue_delayed_work_on(cpu, keventd_wq, dwork, delay); |
1da177e4 | 843 | } |
ae90dd5d | 844 | EXPORT_SYMBOL(schedule_delayed_work_on); |
1da177e4 | 845 | |
b6136773 AM |
846 | /** |
847 | * schedule_on_each_cpu - call a function on each online CPU from keventd | |
848 | * @func: the function to call | |
b6136773 AM |
849 | * |
850 | * Returns zero on success. | |
851 | * Returns -ve errno on failure. | |
852 | * | |
b6136773 AM |
853 | * schedule_on_each_cpu() is very slow. |
854 | */ | |
65f27f38 | 855 | int schedule_on_each_cpu(work_func_t func) |
15316ba8 CL |
856 | { |
857 | int cpu; | |
65a64464 | 858 | int orig = -1; |
b6136773 | 859 | struct work_struct *works; |
15316ba8 | 860 | |
b6136773 AM |
861 | works = alloc_percpu(struct work_struct); |
862 | if (!works) | |
15316ba8 | 863 | return -ENOMEM; |
b6136773 | 864 | |
93981800 TH |
865 | get_online_cpus(); |
866 | ||
65a64464 | 867 | /* |
93981800 TH |
868 | * When running in keventd don't schedule a work item on |
869 | * itself. Can just call directly because the work queue is | |
870 | * already bound. This also is faster. | |
65a64464 | 871 | */ |
93981800 | 872 | if (current_is_keventd()) |
65a64464 | 873 | orig = raw_smp_processor_id(); |
65a64464 | 874 | |
15316ba8 | 875 | for_each_online_cpu(cpu) { |
9bfb1839 IM |
876 | struct work_struct *work = per_cpu_ptr(works, cpu); |
877 | ||
878 | INIT_WORK(work, func); | |
65a64464 | 879 | if (cpu != orig) |
93981800 | 880 | schedule_work_on(cpu, work); |
65a64464 | 881 | } |
93981800 TH |
882 | if (orig >= 0) |
883 | func(per_cpu_ptr(works, orig)); | |
884 | ||
885 | for_each_online_cpu(cpu) | |
886 | flush_work(per_cpu_ptr(works, cpu)); | |
887 | ||
95402b38 | 888 | put_online_cpus(); |
b6136773 | 889 | free_percpu(works); |
15316ba8 CL |
890 | return 0; |
891 | } | |
892 | ||
eef6a7d5 AS |
893 | /** |
894 | * flush_scheduled_work - ensure that any scheduled work has run to completion. | |
895 | * | |
896 | * Forces execution of the kernel-global workqueue and blocks until its | |
897 | * completion. | |
898 | * | |
899 | * Think twice before calling this function! It's very easy to get into | |
900 | * trouble if you don't take great care. Either of the following situations | |
901 | * will lead to deadlock: | |
902 | * | |
903 | * One of the work items currently on the workqueue needs to acquire | |
904 | * a lock held by your code or its caller. | |
905 | * | |
906 | * Your code is running in the context of a work routine. | |
907 | * | |
908 | * They will be detected by lockdep when they occur, but the first might not | |
909 | * occur very often. It depends on what work items are on the workqueue and | |
910 | * what locks they need, which you have no control over. | |
911 | * | |
912 | * In most situations flushing the entire workqueue is overkill; you merely | |
913 | * need to know that a particular work item isn't queued and isn't running. | |
914 | * In such cases you should use cancel_delayed_work_sync() or | |
915 | * cancel_work_sync() instead. | |
916 | */ | |
1da177e4 LT |
917 | void flush_scheduled_work(void) |
918 | { | |
919 | flush_workqueue(keventd_wq); | |
920 | } | |
ae90dd5d | 921 | EXPORT_SYMBOL(flush_scheduled_work); |
1da177e4 | 922 | |
1fa44eca JB |
923 | /** |
924 | * execute_in_process_context - reliably execute the routine with user context | |
925 | * @fn: the function to execute | |
1fa44eca JB |
926 | * @ew: guaranteed storage for the execute work structure (must |
927 | * be available when the work executes) | |
928 | * | |
929 | * Executes the function immediately if process context is available, | |
930 | * otherwise schedules the function for delayed execution. | |
931 | * | |
932 | * Returns: 0 - function was executed | |
933 | * 1 - function was scheduled for execution | |
934 | */ | |
65f27f38 | 935 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
1fa44eca JB |
936 | { |
937 | if (!in_interrupt()) { | |
65f27f38 | 938 | fn(&ew->work); |
1fa44eca JB |
939 | return 0; |
940 | } | |
941 | ||
65f27f38 | 942 | INIT_WORK(&ew->work, fn); |
1fa44eca JB |
943 | schedule_work(&ew->work); |
944 | ||
945 | return 1; | |
946 | } | |
947 | EXPORT_SYMBOL_GPL(execute_in_process_context); | |
948 | ||
1da177e4 LT |
949 | int keventd_up(void) |
950 | { | |
951 | return keventd_wq != NULL; | |
952 | } | |
953 | ||
954 | int current_is_keventd(void) | |
955 | { | |
956 | struct cpu_workqueue_struct *cwq; | |
d243769d | 957 | int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */ |
1da177e4 LT |
958 | int ret = 0; |
959 | ||
960 | BUG_ON(!keventd_wq); | |
961 | ||
1537663f | 962 | cwq = get_cwq(cpu, keventd_wq); |
1da177e4 LT |
963 | if (current == cwq->thread) |
964 | ret = 1; | |
965 | ||
966 | return ret; | |
967 | ||
968 | } | |
969 | ||
3af24433 ON |
970 | static int create_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) |
971 | { | |
972 | struct workqueue_struct *wq = cwq->wq; | |
3af24433 ON |
973 | struct task_struct *p; |
974 | ||
1537663f | 975 | p = kthread_create(worker_thread, cwq, "%s/%d", wq->name, cpu); |
3af24433 ON |
976 | /* |
977 | * Nobody can add the work_struct to this cwq, | |
978 | * if (caller is __create_workqueue) | |
979 | * nobody should see this wq | |
980 | * else // caller is CPU_UP_PREPARE | |
981 | * cpu is not on cpu_online_map | |
982 | * so we can abort safely. | |
983 | */ | |
984 | if (IS_ERR(p)) | |
985 | return PTR_ERR(p); | |
3af24433 | 986 | cwq->thread = p; |
3af24433 ON |
987 | |
988 | return 0; | |
989 | } | |
990 | ||
06ba38a9 ON |
991 | static void start_workqueue_thread(struct cpu_workqueue_struct *cwq, int cpu) |
992 | { | |
993 | struct task_struct *p = cwq->thread; | |
994 | ||
995 | if (p != NULL) { | |
996 | if (cpu >= 0) | |
997 | kthread_bind(p, cpu); | |
998 | wake_up_process(p); | |
999 | } | |
1000 | } | |
1001 | ||
4e6045f1 | 1002 | struct workqueue_struct *__create_workqueue_key(const char *name, |
97e37d7b | 1003 | unsigned int flags, |
eb13ba87 JB |
1004 | struct lock_class_key *key, |
1005 | const char *lock_name) | |
1da177e4 | 1006 | { |
1537663f | 1007 | bool singlethread = flags & WQ_SINGLE_THREAD; |
1da177e4 | 1008 | struct workqueue_struct *wq; |
3af24433 | 1009 | int err = 0, cpu; |
1da177e4 | 1010 | |
3af24433 ON |
1011 | wq = kzalloc(sizeof(*wq), GFP_KERNEL); |
1012 | if (!wq) | |
4690c4ab | 1013 | goto err; |
3af24433 ON |
1014 | |
1015 | wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct); | |
4690c4ab TH |
1016 | if (!wq->cpu_wq) |
1017 | goto err; | |
3af24433 | 1018 | |
97e37d7b | 1019 | wq->flags = flags; |
3af24433 | 1020 | wq->name = name; |
eb13ba87 | 1021 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
cce1a165 | 1022 | INIT_LIST_HEAD(&wq->list); |
3af24433 | 1023 | |
1537663f TH |
1024 | cpu_maps_update_begin(); |
1025 | /* | |
1026 | * We must initialize cwqs for each possible cpu even if we | |
1027 | * are going to call destroy_workqueue() finally. Otherwise | |
1028 | * cpu_up() can hit the uninitialized cwq once we drop the | |
1029 | * lock. | |
1030 | */ | |
1031 | for_each_possible_cpu(cpu) { | |
1032 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
1033 | ||
1034 | cwq->wq = wq; | |
1035 | cwq->cpu = cpu; | |
1036 | spin_lock_init(&cwq->lock); | |
1037 | INIT_LIST_HEAD(&cwq->worklist); | |
1038 | init_waitqueue_head(&cwq->more_work); | |
1039 | ||
1040 | if (err) | |
1041 | continue; | |
1042 | err = create_workqueue_thread(cwq, cpu); | |
1043 | if (cpu_online(cpu) && !singlethread) | |
06ba38a9 | 1044 | start_workqueue_thread(cwq, cpu); |
1537663f TH |
1045 | else |
1046 | start_workqueue_thread(cwq, -1); | |
3af24433 ON |
1047 | } |
1048 | ||
1537663f TH |
1049 | spin_lock(&workqueue_lock); |
1050 | list_add(&wq->list, &workqueues); | |
1051 | spin_unlock(&workqueue_lock); | |
1052 | ||
1053 | cpu_maps_update_done(); | |
1054 | ||
3af24433 ON |
1055 | if (err) { |
1056 | destroy_workqueue(wq); | |
1057 | wq = NULL; | |
1058 | } | |
1059 | return wq; | |
4690c4ab TH |
1060 | err: |
1061 | if (wq) { | |
1062 | free_percpu(wq->cpu_wq); | |
1063 | kfree(wq); | |
1064 | } | |
1065 | return NULL; | |
3af24433 | 1066 | } |
4e6045f1 | 1067 | EXPORT_SYMBOL_GPL(__create_workqueue_key); |
1da177e4 | 1068 | |
1e35eaa2 | 1069 | static void cleanup_workqueue_thread(struct cpu_workqueue_struct *cwq) |
3af24433 | 1070 | { |
14441960 | 1071 | /* |
3da1c84c ON |
1072 | * Our caller is either destroy_workqueue() or CPU_POST_DEAD, |
1073 | * cpu_add_remove_lock protects cwq->thread. | |
14441960 ON |
1074 | */ |
1075 | if (cwq->thread == NULL) | |
1076 | return; | |
3af24433 | 1077 | |
3295f0ef IM |
1078 | lock_map_acquire(&cwq->wq->lockdep_map); |
1079 | lock_map_release(&cwq->wq->lockdep_map); | |
4e6045f1 | 1080 | |
13c22168 | 1081 | flush_cpu_workqueue(cwq); |
14441960 | 1082 | /* |
3da1c84c | 1083 | * If the caller is CPU_POST_DEAD and cwq->worklist was not empty, |
13c22168 ON |
1084 | * a concurrent flush_workqueue() can insert a barrier after us. |
1085 | * However, in that case run_workqueue() won't return and check | |
1086 | * kthread_should_stop() until it flushes all work_struct's. | |
14441960 ON |
1087 | * When ->worklist becomes empty it is safe to exit because no |
1088 | * more work_structs can be queued on this cwq: flush_workqueue | |
1089 | * checks list_empty(), and a "normal" queue_work() can't use | |
1090 | * a dead CPU. | |
1091 | */ | |
14441960 ON |
1092 | kthread_stop(cwq->thread); |
1093 | cwq->thread = NULL; | |
3af24433 ON |
1094 | } |
1095 | ||
1096 | /** | |
1097 | * destroy_workqueue - safely terminate a workqueue | |
1098 | * @wq: target workqueue | |
1099 | * | |
1100 | * Safely destroy a workqueue. All work currently pending will be done first. | |
1101 | */ | |
1102 | void destroy_workqueue(struct workqueue_struct *wq) | |
1103 | { | |
b1f4ec17 | 1104 | int cpu; |
3af24433 | 1105 | |
3da1c84c | 1106 | cpu_maps_update_begin(); |
95402b38 | 1107 | spin_lock(&workqueue_lock); |
b1f4ec17 | 1108 | list_del(&wq->list); |
95402b38 | 1109 | spin_unlock(&workqueue_lock); |
1537663f | 1110 | cpu_maps_update_done(); |
3af24433 | 1111 | |
1537663f TH |
1112 | for_each_possible_cpu(cpu) |
1113 | cleanup_workqueue_thread(get_cwq(cpu, wq)); | |
9b41ea72 | 1114 | |
3af24433 ON |
1115 | free_percpu(wq->cpu_wq); |
1116 | kfree(wq); | |
1117 | } | |
1118 | EXPORT_SYMBOL_GPL(destroy_workqueue); | |
1119 | ||
1120 | static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, | |
1121 | unsigned long action, | |
1122 | void *hcpu) | |
1123 | { | |
1124 | unsigned int cpu = (unsigned long)hcpu; | |
1125 | struct cpu_workqueue_struct *cwq; | |
1126 | struct workqueue_struct *wq; | |
1127 | ||
8bb78442 RW |
1128 | action &= ~CPU_TASKS_FROZEN; |
1129 | ||
3af24433 | 1130 | list_for_each_entry(wq, &workqueues, list) { |
1537663f TH |
1131 | if (wq->flags & WQ_SINGLE_THREAD) |
1132 | continue; | |
3af24433 | 1133 | |
1537663f | 1134 | cwq = get_cwq(cpu, wq); |
3af24433 | 1135 | |
1537663f | 1136 | switch (action) { |
3da1c84c | 1137 | case CPU_POST_DEAD: |
1537663f TH |
1138 | lock_map_acquire(&cwq->wq->lockdep_map); |
1139 | lock_map_release(&cwq->wq->lockdep_map); | |
1140 | flush_cpu_workqueue(cwq); | |
3af24433 ON |
1141 | break; |
1142 | } | |
1da177e4 LT |
1143 | } |
1144 | ||
1537663f | 1145 | return notifier_from_errno(0); |
1da177e4 | 1146 | } |
1da177e4 | 1147 | |
2d3854a3 | 1148 | #ifdef CONFIG_SMP |
8ccad40d | 1149 | |
2d3854a3 | 1150 | struct work_for_cpu { |
6b44003e | 1151 | struct completion completion; |
2d3854a3 RR |
1152 | long (*fn)(void *); |
1153 | void *arg; | |
1154 | long ret; | |
1155 | }; | |
1156 | ||
6b44003e | 1157 | static int do_work_for_cpu(void *_wfc) |
2d3854a3 | 1158 | { |
6b44003e | 1159 | struct work_for_cpu *wfc = _wfc; |
2d3854a3 | 1160 | wfc->ret = wfc->fn(wfc->arg); |
6b44003e AM |
1161 | complete(&wfc->completion); |
1162 | return 0; | |
2d3854a3 RR |
1163 | } |
1164 | ||
1165 | /** | |
1166 | * work_on_cpu - run a function in user context on a particular cpu | |
1167 | * @cpu: the cpu to run on | |
1168 | * @fn: the function to run | |
1169 | * @arg: the function arg | |
1170 | * | |
31ad9081 RR |
1171 | * This will return the value @fn returns. |
1172 | * It is up to the caller to ensure that the cpu doesn't go offline. | |
6b44003e | 1173 | * The caller must not hold any locks which would prevent @fn from completing. |
2d3854a3 RR |
1174 | */ |
1175 | long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) | |
1176 | { | |
6b44003e AM |
1177 | struct task_struct *sub_thread; |
1178 | struct work_for_cpu wfc = { | |
1179 | .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), | |
1180 | .fn = fn, | |
1181 | .arg = arg, | |
1182 | }; | |
1183 | ||
1184 | sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); | |
1185 | if (IS_ERR(sub_thread)) | |
1186 | return PTR_ERR(sub_thread); | |
1187 | kthread_bind(sub_thread, cpu); | |
1188 | wake_up_process(sub_thread); | |
1189 | wait_for_completion(&wfc.completion); | |
2d3854a3 RR |
1190 | return wfc.ret; |
1191 | } | |
1192 | EXPORT_SYMBOL_GPL(work_on_cpu); | |
1193 | #endif /* CONFIG_SMP */ | |
1194 | ||
c12920d1 | 1195 | void __init init_workqueues(void) |
1da177e4 | 1196 | { |
e7577c50 | 1197 | singlethread_cpu = cpumask_first(cpu_possible_mask); |
1da177e4 LT |
1198 | hotcpu_notifier(workqueue_cpu_callback, 0); |
1199 | keventd_wq = create_workqueue("events"); | |
1200 | BUG_ON(!keventd_wq); | |
1201 | } |