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07fe7cb7 DH |
1 | /* Worker thread pool for slow items, such as filesystem lookups or mkdirs |
2 | * | |
3 | * Copyright (C) 2008 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public Licence | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the Licence, or (at your option) any later version. | |
8f0aa2f2 DH |
10 | * |
11 | * See Documentation/slow-work.txt | |
07fe7cb7 DH |
12 | */ |
13 | ||
14 | #include <linux/module.h> | |
15 | #include <linux/slow-work.h> | |
16 | #include <linux/kthread.h> | |
17 | #include <linux/freezer.h> | |
18 | #include <linux/wait.h> | |
f13a48bd | 19 | #include <linux/debugfs.h> |
8fba10a4 | 20 | #include "slow-work.h" |
3d7a641e | 21 | |
109d9272 DH |
22 | static void slow_work_cull_timeout(unsigned long); |
23 | static void slow_work_oom_timeout(unsigned long); | |
24 | ||
12e22c5e | 25 | #ifdef CONFIG_SYSCTL |
8d65af78 | 26 | static int slow_work_min_threads_sysctl(struct ctl_table *, int, |
12e22c5e DH |
27 | void __user *, size_t *, loff_t *); |
28 | ||
8d65af78 | 29 | static int slow_work_max_threads_sysctl(struct ctl_table *, int , |
12e22c5e DH |
30 | void __user *, size_t *, loff_t *); |
31 | #endif | |
32 | ||
07fe7cb7 DH |
33 | /* |
34 | * The pool of threads has at least min threads in it as long as someone is | |
35 | * using the facility, and may have as many as max. | |
36 | * | |
37 | * A portion of the pool may be processing very slow operations. | |
38 | */ | |
39 | static unsigned slow_work_min_threads = 2; | |
40 | static unsigned slow_work_max_threads = 4; | |
41 | static unsigned vslow_work_proportion = 50; /* % of threads that may process | |
42 | * very slow work */ | |
12e22c5e DH |
43 | |
44 | #ifdef CONFIG_SYSCTL | |
45 | static const int slow_work_min_min_threads = 2; | |
3d7a641e | 46 | static int slow_work_max_max_threads = SLOW_WORK_THREAD_LIMIT; |
12e22c5e DH |
47 | static const int slow_work_min_vslow = 1; |
48 | static const int slow_work_max_vslow = 99; | |
49 | ||
50 | ctl_table slow_work_sysctls[] = { | |
51 | { | |
52 | .ctl_name = CTL_UNNUMBERED, | |
53 | .procname = "min-threads", | |
54 | .data = &slow_work_min_threads, | |
55 | .maxlen = sizeof(unsigned), | |
56 | .mode = 0644, | |
57 | .proc_handler = slow_work_min_threads_sysctl, | |
58 | .extra1 = (void *) &slow_work_min_min_threads, | |
59 | .extra2 = &slow_work_max_threads, | |
60 | }, | |
61 | { | |
62 | .ctl_name = CTL_UNNUMBERED, | |
63 | .procname = "max-threads", | |
64 | .data = &slow_work_max_threads, | |
65 | .maxlen = sizeof(unsigned), | |
66 | .mode = 0644, | |
67 | .proc_handler = slow_work_max_threads_sysctl, | |
68 | .extra1 = &slow_work_min_threads, | |
69 | .extra2 = (void *) &slow_work_max_max_threads, | |
70 | }, | |
71 | { | |
72 | .ctl_name = CTL_UNNUMBERED, | |
73 | .procname = "vslow-percentage", | |
74 | .data = &vslow_work_proportion, | |
75 | .maxlen = sizeof(unsigned), | |
76 | .mode = 0644, | |
77 | .proc_handler = &proc_dointvec_minmax, | |
78 | .extra1 = (void *) &slow_work_min_vslow, | |
79 | .extra2 = (void *) &slow_work_max_vslow, | |
80 | }, | |
81 | { .ctl_name = 0 } | |
82 | }; | |
83 | #endif | |
84 | ||
85 | /* | |
86 | * The active state of the thread pool | |
87 | */ | |
07fe7cb7 DH |
88 | static atomic_t slow_work_thread_count; |
89 | static atomic_t vslow_work_executing_count; | |
90 | ||
109d9272 DH |
91 | static bool slow_work_may_not_start_new_thread; |
92 | static bool slow_work_cull; /* cull a thread due to lack of activity */ | |
93 | static DEFINE_TIMER(slow_work_cull_timer, slow_work_cull_timeout, 0, 0); | |
94 | static DEFINE_TIMER(slow_work_oom_timer, slow_work_oom_timeout, 0, 0); | |
95 | static struct slow_work slow_work_new_thread; /* new thread starter */ | |
96 | ||
3d7a641e DH |
97 | /* |
98 | * slow work ID allocation (use slow_work_queue_lock) | |
99 | */ | |
100 | static DECLARE_BITMAP(slow_work_ids, SLOW_WORK_THREAD_LIMIT); | |
101 | ||
102 | /* | |
103 | * Unregistration tracking to prevent put_ref() from disappearing during module | |
104 | * unload | |
105 | */ | |
106 | #ifdef CONFIG_MODULES | |
107 | static struct module *slow_work_thread_processing[SLOW_WORK_THREAD_LIMIT]; | |
108 | static struct module *slow_work_unreg_module; | |
109 | static struct slow_work *slow_work_unreg_work_item; | |
110 | static DECLARE_WAIT_QUEUE_HEAD(slow_work_unreg_wq); | |
111 | static DEFINE_MUTEX(slow_work_unreg_sync_lock); | |
fa1dae49 DH |
112 | |
113 | static void slow_work_set_thread_processing(int id, struct slow_work *work) | |
114 | { | |
115 | if (work) | |
116 | slow_work_thread_processing[id] = work->owner; | |
117 | } | |
118 | static void slow_work_done_thread_processing(int id, struct slow_work *work) | |
119 | { | |
120 | struct module *module = slow_work_thread_processing[id]; | |
121 | ||
122 | slow_work_thread_processing[id] = NULL; | |
123 | smp_mb(); | |
124 | if (slow_work_unreg_work_item == work || | |
125 | slow_work_unreg_module == module) | |
126 | wake_up_all(&slow_work_unreg_wq); | |
127 | } | |
128 | static void slow_work_clear_thread_processing(int id) | |
129 | { | |
130 | slow_work_thread_processing[id] = NULL; | |
131 | } | |
132 | #else | |
133 | static void slow_work_set_thread_processing(int id, struct slow_work *work) {} | |
134 | static void slow_work_done_thread_processing(int id, struct slow_work *work) {} | |
135 | static void slow_work_clear_thread_processing(int id) {} | |
3d7a641e DH |
136 | #endif |
137 | ||
8fba10a4 DH |
138 | /* |
139 | * Data for tracking currently executing items for indication through /proc | |
140 | */ | |
f13a48bd | 141 | #ifdef CONFIG_SLOW_WORK_DEBUG |
8fba10a4 DH |
142 | struct slow_work *slow_work_execs[SLOW_WORK_THREAD_LIMIT]; |
143 | pid_t slow_work_pids[SLOW_WORK_THREAD_LIMIT]; | |
144 | DEFINE_RWLOCK(slow_work_execs_lock); | |
145 | #endif | |
146 | ||
07fe7cb7 DH |
147 | /* |
148 | * The queues of work items and the lock governing access to them. These are | |
149 | * shared between all the CPUs. It doesn't make sense to have per-CPU queues | |
150 | * as the number of threads bears no relation to the number of CPUs. | |
151 | * | |
152 | * There are two queues of work items: one for slow work items, and one for | |
153 | * very slow work items. | |
154 | */ | |
8fba10a4 DH |
155 | LIST_HEAD(slow_work_queue); |
156 | LIST_HEAD(vslow_work_queue); | |
157 | DEFINE_SPINLOCK(slow_work_queue_lock); | |
07fe7cb7 | 158 | |
3bde31a4 DH |
159 | /* |
160 | * The following are two wait queues that get pinged when a work item is placed | |
161 | * on an empty queue. These allow work items that are hogging a thread by | |
162 | * sleeping in a way that could be deferred to yield their thread and enqueue | |
163 | * themselves. | |
164 | */ | |
165 | static DECLARE_WAIT_QUEUE_HEAD(slow_work_queue_waits_for_occupation); | |
166 | static DECLARE_WAIT_QUEUE_HEAD(vslow_work_queue_waits_for_occupation); | |
167 | ||
07fe7cb7 DH |
168 | /* |
169 | * The thread controls. A variable used to signal to the threads that they | |
170 | * should exit when the queue is empty, a waitqueue used by the threads to wait | |
171 | * for signals, and a completion set by the last thread to exit. | |
172 | */ | |
173 | static bool slow_work_threads_should_exit; | |
174 | static DECLARE_WAIT_QUEUE_HEAD(slow_work_thread_wq); | |
175 | static DECLARE_COMPLETION(slow_work_last_thread_exited); | |
176 | ||
177 | /* | |
178 | * The number of users of the thread pool and its lock. Whilst this is zero we | |
179 | * have no threads hanging around, and when this reaches zero, we wait for all | |
180 | * active or queued work items to complete and kill all the threads we do have. | |
181 | */ | |
182 | static int slow_work_user_count; | |
183 | static DEFINE_MUTEX(slow_work_user_lock); | |
184 | ||
4d8bb2cb JA |
185 | static inline int slow_work_get_ref(struct slow_work *work) |
186 | { | |
187 | if (work->ops->get_ref) | |
188 | return work->ops->get_ref(work); | |
189 | ||
190 | return 0; | |
191 | } | |
192 | ||
193 | static inline void slow_work_put_ref(struct slow_work *work) | |
194 | { | |
195 | if (work->ops->put_ref) | |
196 | work->ops->put_ref(work); | |
197 | } | |
198 | ||
07fe7cb7 DH |
199 | /* |
200 | * Calculate the maximum number of active threads in the pool that are | |
201 | * permitted to process very slow work items. | |
202 | * | |
203 | * The answer is rounded up to at least 1, but may not equal or exceed the | |
204 | * maximum number of the threads in the pool. This means we always have at | |
205 | * least one thread that can process slow work items, and we always have at | |
206 | * least one thread that won't get tied up doing so. | |
207 | */ | |
208 | static unsigned slow_work_calc_vsmax(void) | |
209 | { | |
210 | unsigned vsmax; | |
211 | ||
212 | vsmax = atomic_read(&slow_work_thread_count) * vslow_work_proportion; | |
213 | vsmax /= 100; | |
214 | vsmax = max(vsmax, 1U); | |
215 | return min(vsmax, slow_work_max_threads - 1); | |
216 | } | |
217 | ||
218 | /* | |
219 | * Attempt to execute stuff queued on a slow thread. Return true if we managed | |
220 | * it, false if there was nothing to do. | |
221 | */ | |
8fba10a4 | 222 | static noinline bool slow_work_execute(int id) |
07fe7cb7 DH |
223 | { |
224 | struct slow_work *work = NULL; | |
225 | unsigned vsmax; | |
226 | bool very_slow; | |
227 | ||
228 | vsmax = slow_work_calc_vsmax(); | |
229 | ||
109d9272 DH |
230 | /* see if we can schedule a new thread to be started if we're not |
231 | * keeping up with the work */ | |
232 | if (!waitqueue_active(&slow_work_thread_wq) && | |
233 | (!list_empty(&slow_work_queue) || !list_empty(&vslow_work_queue)) && | |
234 | atomic_read(&slow_work_thread_count) < slow_work_max_threads && | |
235 | !slow_work_may_not_start_new_thread) | |
236 | slow_work_enqueue(&slow_work_new_thread); | |
237 | ||
07fe7cb7 DH |
238 | /* find something to execute */ |
239 | spin_lock_irq(&slow_work_queue_lock); | |
240 | if (!list_empty(&vslow_work_queue) && | |
241 | atomic_read(&vslow_work_executing_count) < vsmax) { | |
242 | work = list_entry(vslow_work_queue.next, | |
243 | struct slow_work, link); | |
244 | if (test_and_set_bit_lock(SLOW_WORK_EXECUTING, &work->flags)) | |
245 | BUG(); | |
246 | list_del_init(&work->link); | |
247 | atomic_inc(&vslow_work_executing_count); | |
248 | very_slow = true; | |
249 | } else if (!list_empty(&slow_work_queue)) { | |
250 | work = list_entry(slow_work_queue.next, | |
251 | struct slow_work, link); | |
252 | if (test_and_set_bit_lock(SLOW_WORK_EXECUTING, &work->flags)) | |
253 | BUG(); | |
254 | list_del_init(&work->link); | |
255 | very_slow = false; | |
256 | } else { | |
257 | very_slow = false; /* avoid the compiler warning */ | |
258 | } | |
3d7a641e | 259 | |
fa1dae49 | 260 | slow_work_set_thread_processing(id, work); |
8fba10a4 DH |
261 | if (work) { |
262 | slow_work_mark_time(work); | |
263 | slow_work_begin_exec(id, work); | |
264 | } | |
3d7a641e | 265 | |
07fe7cb7 DH |
266 | spin_unlock_irq(&slow_work_queue_lock); |
267 | ||
268 | if (!work) | |
269 | return false; | |
270 | ||
271 | if (!test_and_clear_bit(SLOW_WORK_PENDING, &work->flags)) | |
272 | BUG(); | |
273 | ||
01609502 JA |
274 | /* don't execute if the work is in the process of being cancelled */ |
275 | if (!test_bit(SLOW_WORK_CANCELLING, &work->flags)) | |
276 | work->ops->execute(work); | |
07fe7cb7 DH |
277 | |
278 | if (very_slow) | |
279 | atomic_dec(&vslow_work_executing_count); | |
280 | clear_bit_unlock(SLOW_WORK_EXECUTING, &work->flags); | |
281 | ||
01609502 JA |
282 | /* wake up anyone waiting for this work to be complete */ |
283 | wake_up_bit(&work->flags, SLOW_WORK_EXECUTING); | |
284 | ||
8fba10a4 DH |
285 | slow_work_end_exec(id, work); |
286 | ||
07fe7cb7 DH |
287 | /* if someone tried to enqueue the item whilst we were executing it, |
288 | * then it'll be left unenqueued to avoid multiple threads trying to | |
289 | * execute it simultaneously | |
290 | * | |
291 | * there is, however, a race between us testing the pending flag and | |
292 | * getting the spinlock, and between the enqueuer setting the pending | |
293 | * flag and getting the spinlock, so we use a deferral bit to tell us | |
294 | * if the enqueuer got there first | |
295 | */ | |
296 | if (test_bit(SLOW_WORK_PENDING, &work->flags)) { | |
297 | spin_lock_irq(&slow_work_queue_lock); | |
298 | ||
299 | if (!test_bit(SLOW_WORK_EXECUTING, &work->flags) && | |
300 | test_and_clear_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags)) | |
301 | goto auto_requeue; | |
302 | ||
303 | spin_unlock_irq(&slow_work_queue_lock); | |
304 | } | |
305 | ||
3d7a641e | 306 | /* sort out the race between module unloading and put_ref() */ |
4d8bb2cb | 307 | slow_work_put_ref(work); |
fa1dae49 | 308 | slow_work_done_thread_processing(id, work); |
3d7a641e | 309 | |
07fe7cb7 DH |
310 | return true; |
311 | ||
312 | auto_requeue: | |
313 | /* we must complete the enqueue operation | |
314 | * - we transfer our ref on the item back to the appropriate queue | |
315 | * - don't wake another thread up as we're awake already | |
316 | */ | |
8fba10a4 | 317 | slow_work_mark_time(work); |
07fe7cb7 DH |
318 | if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags)) |
319 | list_add_tail(&work->link, &vslow_work_queue); | |
320 | else | |
321 | list_add_tail(&work->link, &slow_work_queue); | |
322 | spin_unlock_irq(&slow_work_queue_lock); | |
fa1dae49 | 323 | slow_work_clear_thread_processing(id); |
07fe7cb7 DH |
324 | return true; |
325 | } | |
326 | ||
3bde31a4 DH |
327 | /** |
328 | * slow_work_sleep_till_thread_needed - Sleep till thread needed by other work | |
329 | * work: The work item under execution that wants to sleep | |
330 | * _timeout: Scheduler sleep timeout | |
331 | * | |
332 | * Allow a requeueable work item to sleep on a slow-work processor thread until | |
333 | * that thread is needed to do some other work or the sleep is interrupted by | |
334 | * some other event. | |
335 | * | |
336 | * The caller must set up a wake up event before calling this and must have set | |
337 | * the appropriate sleep mode (such as TASK_UNINTERRUPTIBLE) and tested its own | |
338 | * condition before calling this function as no test is made here. | |
339 | * | |
340 | * False is returned if there is nothing on the queue; true is returned if the | |
341 | * work item should be requeued | |
342 | */ | |
343 | bool slow_work_sleep_till_thread_needed(struct slow_work *work, | |
344 | signed long *_timeout) | |
345 | { | |
346 | wait_queue_head_t *wfo_wq; | |
347 | struct list_head *queue; | |
348 | ||
349 | DEFINE_WAIT(wait); | |
350 | ||
351 | if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags)) { | |
352 | wfo_wq = &vslow_work_queue_waits_for_occupation; | |
353 | queue = &vslow_work_queue; | |
354 | } else { | |
355 | wfo_wq = &slow_work_queue_waits_for_occupation; | |
356 | queue = &slow_work_queue; | |
357 | } | |
358 | ||
359 | if (!list_empty(queue)) | |
360 | return true; | |
361 | ||
362 | add_wait_queue_exclusive(wfo_wq, &wait); | |
363 | if (list_empty(queue)) | |
364 | *_timeout = schedule_timeout(*_timeout); | |
365 | finish_wait(wfo_wq, &wait); | |
366 | ||
367 | return !list_empty(queue); | |
368 | } | |
369 | EXPORT_SYMBOL(slow_work_sleep_till_thread_needed); | |
370 | ||
07fe7cb7 DH |
371 | /** |
372 | * slow_work_enqueue - Schedule a slow work item for processing | |
373 | * @work: The work item to queue | |
374 | * | |
375 | * Schedule a slow work item for processing. If the item is already undergoing | |
376 | * execution, this guarantees not to re-enter the execution routine until the | |
377 | * first execution finishes. | |
378 | * | |
379 | * The item is pinned by this function as it retains a reference to it, managed | |
380 | * through the item operations. The item is unpinned once it has been | |
381 | * executed. | |
382 | * | |
383 | * An item may hog the thread that is running it for a relatively large amount | |
384 | * of time, sufficient, for example, to perform several lookup, mkdir, create | |
385 | * and setxattr operations. It may sleep on I/O and may sleep to obtain locks. | |
386 | * | |
387 | * Conversely, if a number of items are awaiting processing, it may take some | |
388 | * time before any given item is given attention. The number of threads in the | |
389 | * pool may be increased to deal with demand, but only up to a limit. | |
390 | * | |
391 | * If SLOW_WORK_VERY_SLOW is set on the work item, then it will be placed in | |
392 | * the very slow queue, from which only a portion of the threads will be | |
393 | * allowed to pick items to execute. This ensures that very slow items won't | |
394 | * overly block ones that are just ordinarily slow. | |
395 | * | |
01609502 JA |
396 | * Returns 0 if successful, -EAGAIN if not (or -ECANCELED if cancelled work is |
397 | * attempted queued) | |
07fe7cb7 DH |
398 | */ |
399 | int slow_work_enqueue(struct slow_work *work) | |
400 | { | |
3bde31a4 DH |
401 | wait_queue_head_t *wfo_wq; |
402 | struct list_head *queue; | |
07fe7cb7 | 403 | unsigned long flags; |
01609502 JA |
404 | int ret; |
405 | ||
406 | if (test_bit(SLOW_WORK_CANCELLING, &work->flags)) | |
407 | return -ECANCELED; | |
07fe7cb7 DH |
408 | |
409 | BUG_ON(slow_work_user_count <= 0); | |
410 | BUG_ON(!work); | |
411 | BUG_ON(!work->ops); | |
07fe7cb7 DH |
412 | |
413 | /* when honouring an enqueue request, we only promise that we will run | |
414 | * the work function in the future; we do not promise to run it once | |
415 | * per enqueue request | |
416 | * | |
417 | * we use the PENDING bit to merge together repeat requests without | |
418 | * having to disable IRQs and take the spinlock, whilst still | |
419 | * maintaining our promise | |
420 | */ | |
421 | if (!test_and_set_bit_lock(SLOW_WORK_PENDING, &work->flags)) { | |
3bde31a4 DH |
422 | if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags)) { |
423 | wfo_wq = &vslow_work_queue_waits_for_occupation; | |
424 | queue = &vslow_work_queue; | |
425 | } else { | |
426 | wfo_wq = &slow_work_queue_waits_for_occupation; | |
427 | queue = &slow_work_queue; | |
428 | } | |
429 | ||
07fe7cb7 DH |
430 | spin_lock_irqsave(&slow_work_queue_lock, flags); |
431 | ||
01609502 JA |
432 | if (unlikely(test_bit(SLOW_WORK_CANCELLING, &work->flags))) |
433 | goto cancelled; | |
434 | ||
07fe7cb7 DH |
435 | /* we promise that we will not attempt to execute the work |
436 | * function in more than one thread simultaneously | |
437 | * | |
438 | * this, however, leaves us with a problem if we're asked to | |
439 | * enqueue the work whilst someone is executing the work | |
440 | * function as simply queueing the work immediately means that | |
441 | * another thread may try executing it whilst it is already | |
442 | * under execution | |
443 | * | |
444 | * to deal with this, we set the ENQ_DEFERRED bit instead of | |
445 | * enqueueing, and the thread currently executing the work | |
446 | * function will enqueue the work item when the work function | |
447 | * returns and it has cleared the EXECUTING bit | |
448 | */ | |
449 | if (test_bit(SLOW_WORK_EXECUTING, &work->flags)) { | |
450 | set_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags); | |
451 | } else { | |
01609502 JA |
452 | ret = slow_work_get_ref(work); |
453 | if (ret < 0) | |
454 | goto failed; | |
8fba10a4 | 455 | slow_work_mark_time(work); |
3bde31a4 | 456 | list_add_tail(&work->link, queue); |
07fe7cb7 | 457 | wake_up(&slow_work_thread_wq); |
3bde31a4 DH |
458 | |
459 | /* if someone who could be requeued is sleeping on a | |
460 | * thread, then ask them to yield their thread */ | |
461 | if (work->link.prev == queue) | |
462 | wake_up(wfo_wq); | |
07fe7cb7 DH |
463 | } |
464 | ||
465 | spin_unlock_irqrestore(&slow_work_queue_lock, flags); | |
466 | } | |
467 | return 0; | |
468 | ||
01609502 JA |
469 | cancelled: |
470 | ret = -ECANCELED; | |
471 | failed: | |
07fe7cb7 | 472 | spin_unlock_irqrestore(&slow_work_queue_lock, flags); |
01609502 | 473 | return ret; |
07fe7cb7 DH |
474 | } |
475 | EXPORT_SYMBOL(slow_work_enqueue); | |
476 | ||
01609502 JA |
477 | static int slow_work_wait(void *word) |
478 | { | |
479 | schedule(); | |
480 | return 0; | |
481 | } | |
482 | ||
483 | /** | |
484 | * slow_work_cancel - Cancel a slow work item | |
485 | * @work: The work item to cancel | |
486 | * | |
487 | * This function will cancel a previously enqueued work item. If we cannot | |
488 | * cancel the work item, it is guarenteed to have run when this function | |
489 | * returns. | |
490 | */ | |
491 | void slow_work_cancel(struct slow_work *work) | |
492 | { | |
493 | bool wait = true, put = false; | |
494 | ||
495 | set_bit(SLOW_WORK_CANCELLING, &work->flags); | |
6b8268b1 JA |
496 | smp_mb(); |
497 | ||
498 | /* if the work item is a delayed work item with an active timer, we | |
499 | * need to wait for the timer to finish _before_ getting the spinlock, | |
500 | * lest we deadlock against the timer routine | |
501 | * | |
502 | * the timer routine will leave DELAYED set if it notices the | |
503 | * CANCELLING flag in time | |
504 | */ | |
505 | if (test_bit(SLOW_WORK_DELAYED, &work->flags)) { | |
506 | struct delayed_slow_work *dwork = | |
507 | container_of(work, struct delayed_slow_work, work); | |
508 | del_timer_sync(&dwork->timer); | |
509 | } | |
01609502 JA |
510 | |
511 | spin_lock_irq(&slow_work_queue_lock); | |
512 | ||
6b8268b1 JA |
513 | if (test_bit(SLOW_WORK_DELAYED, &work->flags)) { |
514 | /* the timer routine aborted or never happened, so we are left | |
515 | * holding the timer's reference on the item and should just | |
516 | * drop the pending flag and wait for any ongoing execution to | |
517 | * finish */ | |
518 | struct delayed_slow_work *dwork = | |
519 | container_of(work, struct delayed_slow_work, work); | |
520 | ||
521 | BUG_ON(timer_pending(&dwork->timer)); | |
522 | BUG_ON(!list_empty(&work->link)); | |
523 | ||
524 | clear_bit(SLOW_WORK_DELAYED, &work->flags); | |
525 | put = true; | |
526 | clear_bit(SLOW_WORK_PENDING, &work->flags); | |
527 | ||
528 | } else if (test_bit(SLOW_WORK_PENDING, &work->flags) && | |
529 | !list_empty(&work->link)) { | |
01609502 JA |
530 | /* the link in the pending queue holds a reference on the item |
531 | * that we will need to release */ | |
532 | list_del_init(&work->link); | |
533 | wait = false; | |
534 | put = true; | |
535 | clear_bit(SLOW_WORK_PENDING, &work->flags); | |
536 | ||
537 | } else if (test_and_clear_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags)) { | |
538 | /* the executor is holding our only reference on the item, so | |
539 | * we merely need to wait for it to finish executing */ | |
540 | clear_bit(SLOW_WORK_PENDING, &work->flags); | |
541 | } | |
542 | ||
543 | spin_unlock_irq(&slow_work_queue_lock); | |
544 | ||
545 | /* the EXECUTING flag is set by the executor whilst the spinlock is set | |
546 | * and before the item is dequeued - so assuming the above doesn't | |
547 | * actually dequeue it, simply waiting for the EXECUTING flag to be | |
548 | * released here should be sufficient */ | |
549 | if (wait) | |
550 | wait_on_bit(&work->flags, SLOW_WORK_EXECUTING, slow_work_wait, | |
551 | TASK_UNINTERRUPTIBLE); | |
552 | ||
553 | clear_bit(SLOW_WORK_CANCELLING, &work->flags); | |
554 | if (put) | |
555 | slow_work_put_ref(work); | |
556 | } | |
557 | EXPORT_SYMBOL(slow_work_cancel); | |
558 | ||
6b8268b1 JA |
559 | /* |
560 | * Handle expiry of the delay timer, indicating that a delayed slow work item | |
561 | * should now be queued if not cancelled | |
562 | */ | |
563 | static void delayed_slow_work_timer(unsigned long data) | |
564 | { | |
3bde31a4 DH |
565 | wait_queue_head_t *wfo_wq; |
566 | struct list_head *queue; | |
6b8268b1 JA |
567 | struct slow_work *work = (struct slow_work *) data; |
568 | unsigned long flags; | |
3bde31a4 DH |
569 | bool queued = false, put = false, first = false; |
570 | ||
571 | if (test_bit(SLOW_WORK_VERY_SLOW, &work->flags)) { | |
572 | wfo_wq = &vslow_work_queue_waits_for_occupation; | |
573 | queue = &vslow_work_queue; | |
574 | } else { | |
575 | wfo_wq = &slow_work_queue_waits_for_occupation; | |
576 | queue = &slow_work_queue; | |
577 | } | |
6b8268b1 JA |
578 | |
579 | spin_lock_irqsave(&slow_work_queue_lock, flags); | |
580 | if (likely(!test_bit(SLOW_WORK_CANCELLING, &work->flags))) { | |
581 | clear_bit(SLOW_WORK_DELAYED, &work->flags); | |
582 | ||
583 | if (test_bit(SLOW_WORK_EXECUTING, &work->flags)) { | |
584 | /* we discard the reference the timer was holding in | |
585 | * favour of the one the executor holds */ | |
586 | set_bit(SLOW_WORK_ENQ_DEFERRED, &work->flags); | |
587 | put = true; | |
588 | } else { | |
8fba10a4 | 589 | slow_work_mark_time(work); |
3bde31a4 | 590 | list_add_tail(&work->link, queue); |
6b8268b1 | 591 | queued = true; |
3bde31a4 DH |
592 | if (work->link.prev == queue) |
593 | first = true; | |
6b8268b1 JA |
594 | } |
595 | } | |
596 | ||
597 | spin_unlock_irqrestore(&slow_work_queue_lock, flags); | |
598 | if (put) | |
599 | slow_work_put_ref(work); | |
3bde31a4 DH |
600 | if (first) |
601 | wake_up(wfo_wq); | |
6b8268b1 JA |
602 | if (queued) |
603 | wake_up(&slow_work_thread_wq); | |
604 | } | |
605 | ||
606 | /** | |
607 | * delayed_slow_work_enqueue - Schedule a delayed slow work item for processing | |
608 | * @dwork: The delayed work item to queue | |
609 | * @delay: When to start executing the work, in jiffies from now | |
610 | * | |
611 | * This is similar to slow_work_enqueue(), but it adds a delay before the work | |
612 | * is actually queued for processing. | |
613 | * | |
614 | * The item can have delayed processing requested on it whilst it is being | |
615 | * executed. The delay will begin immediately, and if it expires before the | |
616 | * item finishes executing, the item will be placed back on the queue when it | |
617 | * has done executing. | |
618 | */ | |
619 | int delayed_slow_work_enqueue(struct delayed_slow_work *dwork, | |
620 | unsigned long delay) | |
621 | { | |
622 | struct slow_work *work = &dwork->work; | |
623 | unsigned long flags; | |
624 | int ret; | |
625 | ||
626 | if (delay == 0) | |
627 | return slow_work_enqueue(&dwork->work); | |
628 | ||
629 | BUG_ON(slow_work_user_count <= 0); | |
630 | BUG_ON(!work); | |
631 | BUG_ON(!work->ops); | |
632 | ||
633 | if (test_bit(SLOW_WORK_CANCELLING, &work->flags)) | |
634 | return -ECANCELED; | |
635 | ||
636 | if (!test_and_set_bit_lock(SLOW_WORK_PENDING, &work->flags)) { | |
637 | spin_lock_irqsave(&slow_work_queue_lock, flags); | |
638 | ||
639 | if (test_bit(SLOW_WORK_CANCELLING, &work->flags)) | |
640 | goto cancelled; | |
641 | ||
642 | /* the timer holds a reference whilst it is pending */ | |
643 | ret = work->ops->get_ref(work); | |
644 | if (ret < 0) | |
645 | goto cant_get_ref; | |
646 | ||
647 | if (test_and_set_bit(SLOW_WORK_DELAYED, &work->flags)) | |
648 | BUG(); | |
649 | dwork->timer.expires = jiffies + delay; | |
650 | dwork->timer.data = (unsigned long) work; | |
651 | dwork->timer.function = delayed_slow_work_timer; | |
652 | add_timer(&dwork->timer); | |
653 | ||
654 | spin_unlock_irqrestore(&slow_work_queue_lock, flags); | |
655 | } | |
656 | ||
657 | return 0; | |
658 | ||
659 | cancelled: | |
660 | ret = -ECANCELED; | |
661 | cant_get_ref: | |
662 | spin_unlock_irqrestore(&slow_work_queue_lock, flags); | |
663 | return ret; | |
664 | } | |
665 | EXPORT_SYMBOL(delayed_slow_work_enqueue); | |
666 | ||
009789f0 CP |
667 | /* |
668 | * Schedule a cull of the thread pool at some time in the near future | |
669 | */ | |
670 | static void slow_work_schedule_cull(void) | |
671 | { | |
672 | mod_timer(&slow_work_cull_timer, | |
673 | round_jiffies(jiffies + SLOW_WORK_CULL_TIMEOUT)); | |
674 | } | |
675 | ||
109d9272 DH |
676 | /* |
677 | * Worker thread culling algorithm | |
678 | */ | |
679 | static bool slow_work_cull_thread(void) | |
680 | { | |
681 | unsigned long flags; | |
682 | bool do_cull = false; | |
683 | ||
684 | spin_lock_irqsave(&slow_work_queue_lock, flags); | |
685 | ||
686 | if (slow_work_cull) { | |
687 | slow_work_cull = false; | |
688 | ||
689 | if (list_empty(&slow_work_queue) && | |
690 | list_empty(&vslow_work_queue) && | |
691 | atomic_read(&slow_work_thread_count) > | |
692 | slow_work_min_threads) { | |
009789f0 | 693 | slow_work_schedule_cull(); |
109d9272 DH |
694 | do_cull = true; |
695 | } | |
696 | } | |
697 | ||
698 | spin_unlock_irqrestore(&slow_work_queue_lock, flags); | |
699 | return do_cull; | |
700 | } | |
701 | ||
07fe7cb7 DH |
702 | /* |
703 | * Determine if there is slow work available for dispatch | |
704 | */ | |
705 | static inline bool slow_work_available(int vsmax) | |
706 | { | |
707 | return !list_empty(&slow_work_queue) || | |
708 | (!list_empty(&vslow_work_queue) && | |
709 | atomic_read(&vslow_work_executing_count) < vsmax); | |
710 | } | |
711 | ||
712 | /* | |
713 | * Worker thread dispatcher | |
714 | */ | |
715 | static int slow_work_thread(void *_data) | |
716 | { | |
3d7a641e | 717 | int vsmax, id; |
07fe7cb7 DH |
718 | |
719 | DEFINE_WAIT(wait); | |
720 | ||
721 | set_freezable(); | |
722 | set_user_nice(current, -5); | |
723 | ||
3d7a641e DH |
724 | /* allocate ourselves an ID */ |
725 | spin_lock_irq(&slow_work_queue_lock); | |
726 | id = find_first_zero_bit(slow_work_ids, SLOW_WORK_THREAD_LIMIT); | |
727 | BUG_ON(id < 0 || id >= SLOW_WORK_THREAD_LIMIT); | |
728 | __set_bit(id, slow_work_ids); | |
8fba10a4 | 729 | slow_work_set_thread_pid(id, current->pid); |
3d7a641e DH |
730 | spin_unlock_irq(&slow_work_queue_lock); |
731 | ||
732 | sprintf(current->comm, "kslowd%03u", id); | |
733 | ||
07fe7cb7 DH |
734 | for (;;) { |
735 | vsmax = vslow_work_proportion; | |
736 | vsmax *= atomic_read(&slow_work_thread_count); | |
737 | vsmax /= 100; | |
738 | ||
b415c49a ON |
739 | prepare_to_wait_exclusive(&slow_work_thread_wq, &wait, |
740 | TASK_INTERRUPTIBLE); | |
07fe7cb7 DH |
741 | if (!freezing(current) && |
742 | !slow_work_threads_should_exit && | |
109d9272 DH |
743 | !slow_work_available(vsmax) && |
744 | !slow_work_cull) | |
07fe7cb7 DH |
745 | schedule(); |
746 | finish_wait(&slow_work_thread_wq, &wait); | |
747 | ||
748 | try_to_freeze(); | |
749 | ||
750 | vsmax = vslow_work_proportion; | |
751 | vsmax *= atomic_read(&slow_work_thread_count); | |
752 | vsmax /= 100; | |
753 | ||
3d7a641e | 754 | if (slow_work_available(vsmax) && slow_work_execute(id)) { |
07fe7cb7 | 755 | cond_resched(); |
109d9272 DH |
756 | if (list_empty(&slow_work_queue) && |
757 | list_empty(&vslow_work_queue) && | |
758 | atomic_read(&slow_work_thread_count) > | |
759 | slow_work_min_threads) | |
009789f0 | 760 | slow_work_schedule_cull(); |
07fe7cb7 DH |
761 | continue; |
762 | } | |
763 | ||
764 | if (slow_work_threads_should_exit) | |
765 | break; | |
109d9272 DH |
766 | |
767 | if (slow_work_cull && slow_work_cull_thread()) | |
768 | break; | |
07fe7cb7 DH |
769 | } |
770 | ||
3d7a641e | 771 | spin_lock_irq(&slow_work_queue_lock); |
8fba10a4 | 772 | slow_work_set_thread_pid(id, 0); |
3d7a641e DH |
773 | __clear_bit(id, slow_work_ids); |
774 | spin_unlock_irq(&slow_work_queue_lock); | |
775 | ||
07fe7cb7 DH |
776 | if (atomic_dec_and_test(&slow_work_thread_count)) |
777 | complete_and_exit(&slow_work_last_thread_exited, 0); | |
778 | return 0; | |
779 | } | |
780 | ||
109d9272 DH |
781 | /* |
782 | * Handle thread cull timer expiration | |
783 | */ | |
784 | static void slow_work_cull_timeout(unsigned long data) | |
785 | { | |
786 | slow_work_cull = true; | |
787 | wake_up(&slow_work_thread_wq); | |
788 | } | |
789 | ||
109d9272 DH |
790 | /* |
791 | * Start a new slow work thread | |
792 | */ | |
793 | static void slow_work_new_thread_execute(struct slow_work *work) | |
794 | { | |
795 | struct task_struct *p; | |
796 | ||
797 | if (slow_work_threads_should_exit) | |
798 | return; | |
799 | ||
800 | if (atomic_read(&slow_work_thread_count) >= slow_work_max_threads) | |
801 | return; | |
802 | ||
803 | if (!mutex_trylock(&slow_work_user_lock)) | |
804 | return; | |
805 | ||
806 | slow_work_may_not_start_new_thread = true; | |
807 | atomic_inc(&slow_work_thread_count); | |
808 | p = kthread_run(slow_work_thread, NULL, "kslowd"); | |
809 | if (IS_ERR(p)) { | |
810 | printk(KERN_DEBUG "Slow work thread pool: OOM\n"); | |
811 | if (atomic_dec_and_test(&slow_work_thread_count)) | |
812 | BUG(); /* we're running on a slow work thread... */ | |
813 | mod_timer(&slow_work_oom_timer, | |
009789f0 | 814 | round_jiffies(jiffies + SLOW_WORK_OOM_TIMEOUT)); |
109d9272 DH |
815 | } else { |
816 | /* ratelimit the starting of new threads */ | |
817 | mod_timer(&slow_work_oom_timer, jiffies + 1); | |
818 | } | |
819 | ||
820 | mutex_unlock(&slow_work_user_lock); | |
821 | } | |
822 | ||
823 | static const struct slow_work_ops slow_work_new_thread_ops = { | |
3d7a641e | 824 | .owner = THIS_MODULE, |
109d9272 | 825 | .execute = slow_work_new_thread_execute, |
f13a48bd | 826 | #ifdef CONFIG_SLOW_WORK_DEBUG |
8fba10a4 DH |
827 | .desc = slow_work_new_thread_desc, |
828 | #endif | |
109d9272 DH |
829 | }; |
830 | ||
831 | /* | |
832 | * post-OOM new thread start suppression expiration | |
833 | */ | |
834 | static void slow_work_oom_timeout(unsigned long data) | |
835 | { | |
836 | slow_work_may_not_start_new_thread = false; | |
837 | } | |
838 | ||
12e22c5e DH |
839 | #ifdef CONFIG_SYSCTL |
840 | /* | |
841 | * Handle adjustment of the minimum number of threads | |
842 | */ | |
843 | static int slow_work_min_threads_sysctl(struct ctl_table *table, int write, | |
8d65af78 | 844 | void __user *buffer, |
12e22c5e DH |
845 | size_t *lenp, loff_t *ppos) |
846 | { | |
8d65af78 | 847 | int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
12e22c5e DH |
848 | int n; |
849 | ||
850 | if (ret == 0) { | |
851 | mutex_lock(&slow_work_user_lock); | |
852 | if (slow_work_user_count > 0) { | |
853 | /* see if we need to start or stop threads */ | |
854 | n = atomic_read(&slow_work_thread_count) - | |
855 | slow_work_min_threads; | |
856 | ||
857 | if (n < 0 && !slow_work_may_not_start_new_thread) | |
858 | slow_work_enqueue(&slow_work_new_thread); | |
859 | else if (n > 0) | |
009789f0 | 860 | slow_work_schedule_cull(); |
12e22c5e DH |
861 | } |
862 | mutex_unlock(&slow_work_user_lock); | |
863 | } | |
864 | ||
865 | return ret; | |
866 | } | |
867 | ||
868 | /* | |
869 | * Handle adjustment of the maximum number of threads | |
870 | */ | |
871 | static int slow_work_max_threads_sysctl(struct ctl_table *table, int write, | |
8d65af78 | 872 | void __user *buffer, |
12e22c5e DH |
873 | size_t *lenp, loff_t *ppos) |
874 | { | |
8d65af78 | 875 | int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos); |
12e22c5e DH |
876 | int n; |
877 | ||
878 | if (ret == 0) { | |
879 | mutex_lock(&slow_work_user_lock); | |
880 | if (slow_work_user_count > 0) { | |
881 | /* see if we need to stop threads */ | |
882 | n = slow_work_max_threads - | |
883 | atomic_read(&slow_work_thread_count); | |
884 | ||
885 | if (n < 0) | |
009789f0 | 886 | slow_work_schedule_cull(); |
12e22c5e DH |
887 | } |
888 | mutex_unlock(&slow_work_user_lock); | |
889 | } | |
890 | ||
891 | return ret; | |
892 | } | |
893 | #endif /* CONFIG_SYSCTL */ | |
894 | ||
07fe7cb7 DH |
895 | /** |
896 | * slow_work_register_user - Register a user of the facility | |
3d7a641e | 897 | * @module: The module about to make use of the facility |
07fe7cb7 DH |
898 | * |
899 | * Register a user of the facility, starting up the initial threads if there | |
900 | * aren't any other users at this point. This will return 0 if successful, or | |
901 | * an error if not. | |
902 | */ | |
3d7a641e | 903 | int slow_work_register_user(struct module *module) |
07fe7cb7 DH |
904 | { |
905 | struct task_struct *p; | |
906 | int loop; | |
907 | ||
908 | mutex_lock(&slow_work_user_lock); | |
909 | ||
910 | if (slow_work_user_count == 0) { | |
911 | printk(KERN_NOTICE "Slow work thread pool: Starting up\n"); | |
912 | init_completion(&slow_work_last_thread_exited); | |
913 | ||
914 | slow_work_threads_should_exit = false; | |
109d9272 DH |
915 | slow_work_init(&slow_work_new_thread, |
916 | &slow_work_new_thread_ops); | |
917 | slow_work_may_not_start_new_thread = false; | |
918 | slow_work_cull = false; | |
07fe7cb7 DH |
919 | |
920 | /* start the minimum number of threads */ | |
921 | for (loop = 0; loop < slow_work_min_threads; loop++) { | |
922 | atomic_inc(&slow_work_thread_count); | |
923 | p = kthread_run(slow_work_thread, NULL, "kslowd"); | |
924 | if (IS_ERR(p)) | |
925 | goto error; | |
926 | } | |
927 | printk(KERN_NOTICE "Slow work thread pool: Ready\n"); | |
928 | } | |
929 | ||
930 | slow_work_user_count++; | |
931 | mutex_unlock(&slow_work_user_lock); | |
932 | return 0; | |
933 | ||
934 | error: | |
935 | if (atomic_dec_and_test(&slow_work_thread_count)) | |
936 | complete(&slow_work_last_thread_exited); | |
937 | if (loop > 0) { | |
938 | printk(KERN_ERR "Slow work thread pool:" | |
939 | " Aborting startup on ENOMEM\n"); | |
940 | slow_work_threads_should_exit = true; | |
941 | wake_up_all(&slow_work_thread_wq); | |
942 | wait_for_completion(&slow_work_last_thread_exited); | |
943 | printk(KERN_ERR "Slow work thread pool: Aborted\n"); | |
944 | } | |
945 | mutex_unlock(&slow_work_user_lock); | |
946 | return PTR_ERR(p); | |
947 | } | |
948 | EXPORT_SYMBOL(slow_work_register_user); | |
949 | ||
3d7a641e DH |
950 | /* |
951 | * wait for all outstanding items from the calling module to complete | |
952 | * - note that more items may be queued whilst we're waiting | |
953 | */ | |
954 | static void slow_work_wait_for_items(struct module *module) | |
955 | { | |
fa1dae49 | 956 | #ifdef CONFIG_MODULES |
3d7a641e DH |
957 | DECLARE_WAITQUEUE(myself, current); |
958 | struct slow_work *work; | |
959 | int loop; | |
960 | ||
961 | mutex_lock(&slow_work_unreg_sync_lock); | |
962 | add_wait_queue(&slow_work_unreg_wq, &myself); | |
963 | ||
964 | for (;;) { | |
965 | spin_lock_irq(&slow_work_queue_lock); | |
966 | ||
967 | /* first of all, we wait for the last queued item in each list | |
968 | * to be processed */ | |
969 | list_for_each_entry_reverse(work, &vslow_work_queue, link) { | |
970 | if (work->owner == module) { | |
971 | set_current_state(TASK_UNINTERRUPTIBLE); | |
972 | slow_work_unreg_work_item = work; | |
973 | goto do_wait; | |
974 | } | |
975 | } | |
976 | list_for_each_entry_reverse(work, &slow_work_queue, link) { | |
977 | if (work->owner == module) { | |
978 | set_current_state(TASK_UNINTERRUPTIBLE); | |
979 | slow_work_unreg_work_item = work; | |
980 | goto do_wait; | |
981 | } | |
982 | } | |
983 | ||
984 | /* then we wait for the items being processed to finish */ | |
985 | slow_work_unreg_module = module; | |
986 | smp_mb(); | |
987 | for (loop = 0; loop < SLOW_WORK_THREAD_LIMIT; loop++) { | |
988 | if (slow_work_thread_processing[loop] == module) | |
989 | goto do_wait; | |
990 | } | |
991 | spin_unlock_irq(&slow_work_queue_lock); | |
992 | break; /* okay, we're done */ | |
993 | ||
994 | do_wait: | |
995 | spin_unlock_irq(&slow_work_queue_lock); | |
996 | schedule(); | |
997 | slow_work_unreg_work_item = NULL; | |
998 | slow_work_unreg_module = NULL; | |
999 | } | |
1000 | ||
1001 | remove_wait_queue(&slow_work_unreg_wq, &myself); | |
1002 | mutex_unlock(&slow_work_unreg_sync_lock); | |
fa1dae49 | 1003 | #endif /* CONFIG_MODULES */ |
3d7a641e DH |
1004 | } |
1005 | ||
07fe7cb7 DH |
1006 | /** |
1007 | * slow_work_unregister_user - Unregister a user of the facility | |
3d7a641e | 1008 | * @module: The module whose items should be cleared |
07fe7cb7 DH |
1009 | * |
1010 | * Unregister a user of the facility, killing all the threads if this was the | |
1011 | * last one. | |
3d7a641e DH |
1012 | * |
1013 | * This waits for all the work items belonging to the nominated module to go | |
1014 | * away before proceeding. | |
07fe7cb7 | 1015 | */ |
3d7a641e | 1016 | void slow_work_unregister_user(struct module *module) |
07fe7cb7 | 1017 | { |
3d7a641e DH |
1018 | /* first of all, wait for all outstanding items from the calling module |
1019 | * to complete */ | |
1020 | if (module) | |
1021 | slow_work_wait_for_items(module); | |
1022 | ||
1023 | /* then we can actually go about shutting down the facility if need | |
1024 | * be */ | |
07fe7cb7 DH |
1025 | mutex_lock(&slow_work_user_lock); |
1026 | ||
1027 | BUG_ON(slow_work_user_count <= 0); | |
1028 | ||
1029 | slow_work_user_count--; | |
1030 | if (slow_work_user_count == 0) { | |
1031 | printk(KERN_NOTICE "Slow work thread pool: Shutting down\n"); | |
1032 | slow_work_threads_should_exit = true; | |
418df63c JC |
1033 | del_timer_sync(&slow_work_cull_timer); |
1034 | del_timer_sync(&slow_work_oom_timer); | |
07fe7cb7 DH |
1035 | wake_up_all(&slow_work_thread_wq); |
1036 | wait_for_completion(&slow_work_last_thread_exited); | |
1037 | printk(KERN_NOTICE "Slow work thread pool:" | |
1038 | " Shut down complete\n"); | |
1039 | } | |
1040 | ||
1041 | mutex_unlock(&slow_work_user_lock); | |
1042 | } | |
1043 | EXPORT_SYMBOL(slow_work_unregister_user); | |
1044 | ||
1045 | /* | |
1046 | * Initialise the slow work facility | |
1047 | */ | |
1048 | static int __init init_slow_work(void) | |
1049 | { | |
1050 | unsigned nr_cpus = num_possible_cpus(); | |
1051 | ||
12e22c5e | 1052 | if (slow_work_max_threads < nr_cpus) |
07fe7cb7 | 1053 | slow_work_max_threads = nr_cpus; |
12e22c5e DH |
1054 | #ifdef CONFIG_SYSCTL |
1055 | if (slow_work_max_max_threads < nr_cpus * 2) | |
1056 | slow_work_max_max_threads = nr_cpus * 2; | |
8fba10a4 | 1057 | #endif |
f13a48bd DH |
1058 | #ifdef CONFIG_SLOW_WORK_DEBUG |
1059 | { | |
1060 | struct dentry *dbdir; | |
1061 | ||
1062 | dbdir = debugfs_create_dir("slow_work", NULL); | |
1063 | if (dbdir && !IS_ERR(dbdir)) | |
1064 | debugfs_create_file("runqueue", S_IFREG | 0400, dbdir, | |
1065 | NULL, &slow_work_runqueue_fops); | |
1066 | } | |
12e22c5e | 1067 | #endif |
07fe7cb7 DH |
1068 | return 0; |
1069 | } | |
1070 | ||
1071 | subsys_initcall(init_slow_work); |