Root/
Source at commit cdde9cf73945d547acd3e96f9508c79e84ad0bf1 created 12 years 9 months ago. By Maarten ter Huurne, MMC: JZ4740: Added support for CPU frequency changing | |
---|---|
1 | /* |
2 | * kernel/workqueue.c - generic async execution with shared worker pool |
3 | * |
4 | * Copyright (C) 2002 Ingo Molnar |
5 | * |
6 | * Derived from the taskqueue/keventd code by: |
7 | * David Woodhouse <dwmw2@infradead.org> |
8 | * Andrew Morton |
9 | * Kai Petzke <wpp@marie.physik.tu-berlin.de> |
10 | * Theodore Ts'o <tytso@mit.edu> |
11 | * |
12 | * Made to use alloc_percpu by Christoph Lameter. |
13 | * |
14 | * Copyright (C) 2010 SUSE Linux Products GmbH |
15 | * Copyright (C) 2010 Tejun Heo <tj@kernel.org> |
16 | * |
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. |
22 | * |
23 | * Please read Documentation/workqueue.txt for details. |
24 | */ |
25 | |
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 | |
45 | #include "workqueue_sched.h" |
46 | |
47 | enum { |
48 | /* |
49 | * global_cwq flags |
50 | * |
51 | * A bound gcwq is either associated or disassociated with its CPU. |
52 | * While associated (!DISASSOCIATED), all workers are bound to the |
53 | * CPU and none has %WORKER_UNBOUND set and concurrency management |
54 | * is in effect. |
55 | * |
56 | * While DISASSOCIATED, the cpu may be offline and all workers have |
57 | * %WORKER_UNBOUND set and concurrency management disabled, and may |
58 | * be executing on any CPU. The gcwq behaves as an unbound one. |
59 | * |
60 | * Note that DISASSOCIATED can be flipped only while holding |
61 | * managership of all pools on the gcwq to avoid changing binding |
62 | * state while create_worker() is in progress. |
63 | */ |
64 | GCWQ_DISASSOCIATED = 1 << 0, /* cpu can't serve workers */ |
65 | GCWQ_FREEZING = 1 << 1, /* freeze in progress */ |
66 | |
67 | /* pool flags */ |
68 | POOL_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ |
69 | POOL_MANAGING_WORKERS = 1 << 1, /* managing workers */ |
70 | |
71 | /* worker flags */ |
72 | WORKER_STARTED = 1 << 0, /* started */ |
73 | WORKER_DIE = 1 << 1, /* die die die */ |
74 | WORKER_IDLE = 1 << 2, /* is idle */ |
75 | WORKER_PREP = 1 << 3, /* preparing to run works */ |
76 | WORKER_REBIND = 1 << 5, /* mom is home, come back */ |
77 | WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ |
78 | WORKER_UNBOUND = 1 << 7, /* worker is unbound */ |
79 | |
80 | WORKER_NOT_RUNNING = WORKER_PREP | WORKER_REBIND | WORKER_UNBOUND | |
81 | WORKER_CPU_INTENSIVE, |
82 | |
83 | NR_WORKER_POOLS = 2, /* # worker pools per gcwq */ |
84 | |
85 | BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ |
86 | BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, |
87 | BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, |
88 | |
89 | MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ |
90 | IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ |
91 | |
92 | MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, |
93 | /* call for help after 10ms |
94 | (min two ticks) */ |
95 | MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ |
96 | CREATE_COOLDOWN = HZ, /* time to breath after fail */ |
97 | |
98 | /* |
99 | * Rescue workers are used only on emergencies and shared by |
100 | * all cpus. Give -20. |
101 | */ |
102 | RESCUER_NICE_LEVEL = -20, |
103 | HIGHPRI_NICE_LEVEL = -20, |
104 | }; |
105 | |
106 | /* |
107 | * Structure fields follow one of the following exclusion rules. |
108 | * |
109 | * I: Modifiable by initialization/destruction paths and read-only for |
110 | * everyone else. |
111 | * |
112 | * P: Preemption protected. Disabling preemption is enough and should |
113 | * only be modified and accessed from the local cpu. |
114 | * |
115 | * L: gcwq->lock protected. Access with gcwq->lock held. |
116 | * |
117 | * X: During normal operation, modification requires gcwq->lock and |
118 | * should be done only from local cpu. Either disabling preemption |
119 | * on local cpu or grabbing gcwq->lock is enough for read access. |
120 | * If GCWQ_DISASSOCIATED is set, it's identical to L. |
121 | * |
122 | * F: wq->flush_mutex protected. |
123 | * |
124 | * W: workqueue_lock protected. |
125 | */ |
126 | |
127 | struct global_cwq; |
128 | struct worker_pool; |
129 | struct idle_rebind; |
130 | |
131 | /* |
132 | * The poor guys doing the actual heavy lifting. All on-duty workers |
133 | * are either serving the manager role, on idle list or on busy hash. |
134 | */ |
135 | struct worker { |
136 | /* on idle list while idle, on busy hash table while busy */ |
137 | union { |
138 | struct list_head entry; /* L: while idle */ |
139 | struct hlist_node hentry; /* L: while busy */ |
140 | }; |
141 | |
142 | struct work_struct *current_work; /* L: work being processed */ |
143 | struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ |
144 | struct list_head scheduled; /* L: scheduled works */ |
145 | struct task_struct *task; /* I: worker task */ |
146 | struct worker_pool *pool; /* I: the associated pool */ |
147 | /* 64 bytes boundary on 64bit, 32 on 32bit */ |
148 | unsigned long last_active; /* L: last active timestamp */ |
149 | unsigned int flags; /* X: flags */ |
150 | int id; /* I: worker id */ |
151 | |
152 | /* for rebinding worker to CPU */ |
153 | struct idle_rebind *idle_rebind; /* L: for idle worker */ |
154 | struct work_struct rebind_work; /* L: for busy worker */ |
155 | }; |
156 | |
157 | struct worker_pool { |
158 | struct global_cwq *gcwq; /* I: the owning gcwq */ |
159 | unsigned int flags; /* X: flags */ |
160 | |
161 | struct list_head worklist; /* L: list of pending works */ |
162 | int nr_workers; /* L: total number of workers */ |
163 | int nr_idle; /* L: currently idle ones */ |
164 | |
165 | struct list_head idle_list; /* X: list of idle workers */ |
166 | struct timer_list idle_timer; /* L: worker idle timeout */ |
167 | struct timer_list mayday_timer; /* L: SOS timer for workers */ |
168 | |
169 | struct mutex manager_mutex; /* mutex manager should hold */ |
170 | struct ida worker_ida; /* L: for worker IDs */ |
171 | }; |
172 | |
173 | /* |
174 | * Global per-cpu workqueue. There's one and only one for each cpu |
175 | * and all works are queued and processed here regardless of their |
176 | * target workqueues. |
177 | */ |
178 | struct global_cwq { |
179 | spinlock_t lock; /* the gcwq lock */ |
180 | unsigned int cpu; /* I: the associated cpu */ |
181 | unsigned int flags; /* L: GCWQ_* flags */ |
182 | |
183 | /* workers are chained either in busy_hash or pool idle_list */ |
184 | struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; |
185 | /* L: hash of busy workers */ |
186 | |
187 | struct worker_pool pools[2]; /* normal and highpri pools */ |
188 | |
189 | wait_queue_head_t rebind_hold; /* rebind hold wait */ |
190 | } ____cacheline_aligned_in_smp; |
191 | |
192 | /* |
193 | * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of |
194 | * work_struct->data are used for flags and thus cwqs need to be |
195 | * aligned at two's power of the number of flag bits. |
196 | */ |
197 | struct cpu_workqueue_struct { |
198 | struct worker_pool *pool; /* I: the associated pool */ |
199 | struct workqueue_struct *wq; /* I: the owning workqueue */ |
200 | int work_color; /* L: current color */ |
201 | int flush_color; /* L: flushing color */ |
202 | int nr_in_flight[WORK_NR_COLORS]; |
203 | /* L: nr of in_flight works */ |
204 | int nr_active; /* L: nr of active works */ |
205 | int max_active; /* L: max active works */ |
206 | struct list_head delayed_works; /* L: delayed works */ |
207 | }; |
208 | |
209 | /* |
210 | * Structure used to wait for workqueue flush. |
211 | */ |
212 | struct wq_flusher { |
213 | struct list_head list; /* F: list of flushers */ |
214 | int flush_color; /* F: flush color waiting for */ |
215 | struct completion done; /* flush completion */ |
216 | }; |
217 | |
218 | /* |
219 | * All cpumasks are assumed to be always set on UP and thus can't be |
220 | * used to determine whether there's something to be done. |
221 | */ |
222 | #ifdef CONFIG_SMP |
223 | typedef cpumask_var_t mayday_mask_t; |
224 | #define mayday_test_and_set_cpu(cpu, mask) \ |
225 | cpumask_test_and_set_cpu((cpu), (mask)) |
226 | #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) |
227 | #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) |
228 | #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp)) |
229 | #define free_mayday_mask(mask) free_cpumask_var((mask)) |
230 | #else |
231 | typedef unsigned long mayday_mask_t; |
232 | #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) |
233 | #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) |
234 | #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) |
235 | #define alloc_mayday_mask(maskp, gfp) true |
236 | #define free_mayday_mask(mask) do { } while (0) |
237 | #endif |
238 | |
239 | /* |
240 | * The externally visible workqueue abstraction is an array of |
241 | * per-CPU workqueues: |
242 | */ |
243 | struct workqueue_struct { |
244 | unsigned int flags; /* W: WQ_* flags */ |
245 | union { |
246 | struct cpu_workqueue_struct __percpu *pcpu; |
247 | struct cpu_workqueue_struct *single; |
248 | unsigned long v; |
249 | } cpu_wq; /* I: cwq's */ |
250 | struct list_head list; /* W: list of all workqueues */ |
251 | |
252 | struct mutex flush_mutex; /* protects wq flushing */ |
253 | int work_color; /* F: current work color */ |
254 | int flush_color; /* F: current flush color */ |
255 | atomic_t nr_cwqs_to_flush; /* flush in progress */ |
256 | struct wq_flusher *first_flusher; /* F: first flusher */ |
257 | struct list_head flusher_queue; /* F: flush waiters */ |
258 | struct list_head flusher_overflow; /* F: flush overflow list */ |
259 | |
260 | mayday_mask_t mayday_mask; /* cpus requesting rescue */ |
261 | struct worker *rescuer; /* I: rescue worker */ |
262 | |
263 | int nr_drainers; /* W: drain in progress */ |
264 | int saved_max_active; /* W: saved cwq max_active */ |
265 | #ifdef CONFIG_LOCKDEP |
266 | struct lockdep_map lockdep_map; |
267 | #endif |
268 | char name[]; /* I: workqueue name */ |
269 | }; |
270 | |
271 | struct workqueue_struct *system_wq __read_mostly; |
272 | struct workqueue_struct *system_long_wq __read_mostly; |
273 | struct workqueue_struct *system_nrt_wq __read_mostly; |
274 | struct workqueue_struct *system_unbound_wq __read_mostly; |
275 | struct workqueue_struct *system_freezable_wq __read_mostly; |
276 | struct workqueue_struct *system_nrt_freezable_wq __read_mostly; |
277 | EXPORT_SYMBOL_GPL(system_wq); |
278 | EXPORT_SYMBOL_GPL(system_long_wq); |
279 | EXPORT_SYMBOL_GPL(system_nrt_wq); |
280 | EXPORT_SYMBOL_GPL(system_unbound_wq); |
281 | EXPORT_SYMBOL_GPL(system_freezable_wq); |
282 | EXPORT_SYMBOL_GPL(system_nrt_freezable_wq); |
283 | |
284 | #define CREATE_TRACE_POINTS |
285 | #include <trace/events/workqueue.h> |
286 | |
287 | #define for_each_worker_pool(pool, gcwq) \ |
288 | for ((pool) = &(gcwq)->pools[0]; \ |
289 | (pool) < &(gcwq)->pools[NR_WORKER_POOLS]; (pool)++) |
290 | |
291 | #define for_each_busy_worker(worker, i, pos, gcwq) \ |
292 | for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ |
293 | hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) |
294 | |
295 | static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask, |
296 | unsigned int sw) |
297 | { |
298 | if (cpu < nr_cpu_ids) { |
299 | if (sw & 1) { |
300 | cpu = cpumask_next(cpu, mask); |
301 | if (cpu < nr_cpu_ids) |
302 | return cpu; |
303 | } |
304 | if (sw & 2) |
305 | return WORK_CPU_UNBOUND; |
306 | } |
307 | return WORK_CPU_NONE; |
308 | } |
309 | |
310 | static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, |
311 | struct workqueue_struct *wq) |
312 | { |
313 | return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); |
314 | } |
315 | |
316 | /* |
317 | * CPU iterators |
318 | * |
319 | * An extra gcwq is defined for an invalid cpu number |
320 | * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any |
321 | * specific CPU. The following iterators are similar to |
322 | * for_each_*_cpu() iterators but also considers the unbound gcwq. |
323 | * |
324 | * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND |
325 | * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND |
326 | * for_each_cwq_cpu() : possible CPUs for bound workqueues, |
327 | * WORK_CPU_UNBOUND for unbound workqueues |
328 | */ |
329 | #define for_each_gcwq_cpu(cpu) \ |
330 | for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \ |
331 | (cpu) < WORK_CPU_NONE; \ |
332 | (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3)) |
333 | |
334 | #define for_each_online_gcwq_cpu(cpu) \ |
335 | for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \ |
336 | (cpu) < WORK_CPU_NONE; \ |
337 | (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3)) |
338 | |
339 | #define for_each_cwq_cpu(cpu, wq) \ |
340 | for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \ |
341 | (cpu) < WORK_CPU_NONE; \ |
342 | (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq))) |
343 | |
344 | #ifdef CONFIG_DEBUG_OBJECTS_WORK |
345 | |
346 | static struct debug_obj_descr work_debug_descr; |
347 | |
348 | static void *work_debug_hint(void *addr) |
349 | { |
350 | return ((struct work_struct *) addr)->func; |
351 | } |
352 | |
353 | /* |
354 | * fixup_init is called when: |
355 | * - an active object is initialized |
356 | */ |
357 | static int work_fixup_init(void *addr, enum debug_obj_state state) |
358 | { |
359 | struct work_struct *work = addr; |
360 | |
361 | switch (state) { |
362 | case ODEBUG_STATE_ACTIVE: |
363 | cancel_work_sync(work); |
364 | debug_object_init(work, &work_debug_descr); |
365 | return 1; |
366 | default: |
367 | return 0; |
368 | } |
369 | } |
370 | |
371 | /* |
372 | * fixup_activate is called when: |
373 | * - an active object is activated |
374 | * - an unknown object is activated (might be a statically initialized object) |
375 | */ |
376 | static int work_fixup_activate(void *addr, enum debug_obj_state state) |
377 | { |
378 | struct work_struct *work = addr; |
379 | |
380 | switch (state) { |
381 | |
382 | case ODEBUG_STATE_NOTAVAILABLE: |
383 | /* |
384 | * This is not really a fixup. The work struct was |
385 | * statically initialized. We just make sure that it |
386 | * is tracked in the object tracker. |
387 | */ |
388 | if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
389 | debug_object_init(work, &work_debug_descr); |
390 | debug_object_activate(work, &work_debug_descr); |
391 | return 0; |
392 | } |
393 | WARN_ON_ONCE(1); |
394 | return 0; |
395 | |
396 | case ODEBUG_STATE_ACTIVE: |
397 | WARN_ON(1); |
398 | |
399 | default: |
400 | return 0; |
401 | } |
402 | } |
403 | |
404 | /* |
405 | * fixup_free is called when: |
406 | * - an active object is freed |
407 | */ |
408 | static int work_fixup_free(void *addr, enum debug_obj_state state) |
409 | { |
410 | struct work_struct *work = addr; |
411 | |
412 | switch (state) { |
413 | case ODEBUG_STATE_ACTIVE: |
414 | cancel_work_sync(work); |
415 | debug_object_free(work, &work_debug_descr); |
416 | return 1; |
417 | default: |
418 | return 0; |
419 | } |
420 | } |
421 | |
422 | static struct debug_obj_descr work_debug_descr = { |
423 | .name = "work_struct", |
424 | .debug_hint = work_debug_hint, |
425 | .fixup_init = work_fixup_init, |
426 | .fixup_activate = work_fixup_activate, |
427 | .fixup_free = work_fixup_free, |
428 | }; |
429 | |
430 | static inline void debug_work_activate(struct work_struct *work) |
431 | { |
432 | debug_object_activate(work, &work_debug_descr); |
433 | } |
434 | |
435 | static inline void debug_work_deactivate(struct work_struct *work) |
436 | { |
437 | debug_object_deactivate(work, &work_debug_descr); |
438 | } |
439 | |
440 | void __init_work(struct work_struct *work, int onstack) |
441 | { |
442 | if (onstack) |
443 | debug_object_init_on_stack(work, &work_debug_descr); |
444 | else |
445 | debug_object_init(work, &work_debug_descr); |
446 | } |
447 | EXPORT_SYMBOL_GPL(__init_work); |
448 | |
449 | void destroy_work_on_stack(struct work_struct *work) |
450 | { |
451 | debug_object_free(work, &work_debug_descr); |
452 | } |
453 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); |
454 | |
455 | #else |
456 | static inline void debug_work_activate(struct work_struct *work) { } |
457 | static inline void debug_work_deactivate(struct work_struct *work) { } |
458 | #endif |
459 | |
460 | /* Serializes the accesses to the list of workqueues. */ |
461 | static DEFINE_SPINLOCK(workqueue_lock); |
462 | static LIST_HEAD(workqueues); |
463 | static bool workqueue_freezing; /* W: have wqs started freezing? */ |
464 | |
465 | /* |
466 | * The almighty global cpu workqueues. nr_running is the only field |
467 | * which is expected to be used frequently by other cpus via |
468 | * try_to_wake_up(). Put it in a separate cacheline. |
469 | */ |
470 | static DEFINE_PER_CPU(struct global_cwq, global_cwq); |
471 | static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, pool_nr_running[NR_WORKER_POOLS]); |
472 | |
473 | /* |
474 | * Global cpu workqueue and nr_running counter for unbound gcwq. The |
475 | * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its |
476 | * workers have WORKER_UNBOUND set. |
477 | */ |
478 | static struct global_cwq unbound_global_cwq; |
479 | static atomic_t unbound_pool_nr_running[NR_WORKER_POOLS] = { |
480 | [0 ... NR_WORKER_POOLS - 1] = ATOMIC_INIT(0), /* always 0 */ |
481 | }; |
482 | |
483 | static int worker_thread(void *__worker); |
484 | |
485 | static int worker_pool_pri(struct worker_pool *pool) |
486 | { |
487 | return pool - pool->gcwq->pools; |
488 | } |
489 | |
490 | static struct global_cwq *get_gcwq(unsigned int cpu) |
491 | { |
492 | if (cpu != WORK_CPU_UNBOUND) |
493 | return &per_cpu(global_cwq, cpu); |
494 | else |
495 | return &unbound_global_cwq; |
496 | } |
497 | |
498 | static atomic_t *get_pool_nr_running(struct worker_pool *pool) |
499 | { |
500 | int cpu = pool->gcwq->cpu; |
501 | int idx = worker_pool_pri(pool); |
502 | |
503 | if (cpu != WORK_CPU_UNBOUND) |
504 | return &per_cpu(pool_nr_running, cpu)[idx]; |
505 | else |
506 | return &unbound_pool_nr_running[idx]; |
507 | } |
508 | |
509 | static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, |
510 | struct workqueue_struct *wq) |
511 | { |
512 | if (!(wq->flags & WQ_UNBOUND)) { |
513 | if (likely(cpu < nr_cpu_ids)) |
514 | return per_cpu_ptr(wq->cpu_wq.pcpu, cpu); |
515 | } else if (likely(cpu == WORK_CPU_UNBOUND)) |
516 | return wq->cpu_wq.single; |
517 | return NULL; |
518 | } |
519 | |
520 | static unsigned int work_color_to_flags(int color) |
521 | { |
522 | return color << WORK_STRUCT_COLOR_SHIFT; |
523 | } |
524 | |
525 | static int get_work_color(struct work_struct *work) |
526 | { |
527 | return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & |
528 | ((1 << WORK_STRUCT_COLOR_BITS) - 1); |
529 | } |
530 | |
531 | static int work_next_color(int color) |
532 | { |
533 | return (color + 1) % WORK_NR_COLORS; |
534 | } |
535 | |
536 | /* |
537 | * A work's data points to the cwq with WORK_STRUCT_CWQ set while the |
538 | * work is on queue. Once execution starts, WORK_STRUCT_CWQ is |
539 | * cleared and the work data contains the cpu number it was last on. |
540 | * |
541 | * set_work_{cwq|cpu}() and clear_work_data() can be used to set the |
542 | * cwq, cpu or clear work->data. These functions should only be |
543 | * called while the work is owned - ie. while the PENDING bit is set. |
544 | * |
545 | * get_work_[g]cwq() can be used to obtain the gcwq or cwq |
546 | * corresponding to a work. gcwq is available once the work has been |
547 | * queued anywhere after initialization. cwq is available only from |
548 | * queueing until execution starts. |
549 | */ |
550 | static inline void set_work_data(struct work_struct *work, unsigned long data, |
551 | unsigned long flags) |
552 | { |
553 | BUG_ON(!work_pending(work)); |
554 | atomic_long_set(&work->data, data | flags | work_static(work)); |
555 | } |
556 | |
557 | static void set_work_cwq(struct work_struct *work, |
558 | struct cpu_workqueue_struct *cwq, |
559 | unsigned long extra_flags) |
560 | { |
561 | set_work_data(work, (unsigned long)cwq, |
562 | WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); |
563 | } |
564 | |
565 | static void set_work_cpu(struct work_struct *work, unsigned int cpu) |
566 | { |
567 | set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); |
568 | } |
569 | |
570 | static void clear_work_data(struct work_struct *work) |
571 | { |
572 | set_work_data(work, WORK_STRUCT_NO_CPU, 0); |
573 | } |
574 | |
575 | static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) |
576 | { |
577 | unsigned long data = atomic_long_read(&work->data); |
578 | |
579 | if (data & WORK_STRUCT_CWQ) |
580 | return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); |
581 | else |
582 | return NULL; |
583 | } |
584 | |
585 | static struct global_cwq *get_work_gcwq(struct work_struct *work) |
586 | { |
587 | unsigned long data = atomic_long_read(&work->data); |
588 | unsigned int cpu; |
589 | |
590 | if (data & WORK_STRUCT_CWQ) |
591 | return ((struct cpu_workqueue_struct *) |
592 | (data & WORK_STRUCT_WQ_DATA_MASK))->pool->gcwq; |
593 | |
594 | cpu = data >> WORK_STRUCT_FLAG_BITS; |
595 | if (cpu == WORK_CPU_NONE) |
596 | return NULL; |
597 | |
598 | BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); |
599 | return get_gcwq(cpu); |
600 | } |
601 | |
602 | /* |
603 | * Policy functions. These define the policies on how the global worker |
604 | * pools are managed. Unless noted otherwise, these functions assume that |
605 | * they're being called with gcwq->lock held. |
606 | */ |
607 | |
608 | static bool __need_more_worker(struct worker_pool *pool) |
609 | { |
610 | return !atomic_read(get_pool_nr_running(pool)); |
611 | } |
612 | |
613 | /* |
614 | * Need to wake up a worker? Called from anything but currently |
615 | * running workers. |
616 | * |
617 | * Note that, because unbound workers never contribute to nr_running, this |
618 | * function will always return %true for unbound gcwq as long as the |
619 | * worklist isn't empty. |
620 | */ |
621 | static bool need_more_worker(struct worker_pool *pool) |
622 | { |
623 | return !list_empty(&pool->worklist) && __need_more_worker(pool); |
624 | } |
625 | |
626 | /* Can I start working? Called from busy but !running workers. */ |
627 | static bool may_start_working(struct worker_pool *pool) |
628 | { |
629 | return pool->nr_idle; |
630 | } |
631 | |
632 | /* Do I need to keep working? Called from currently running workers. */ |
633 | static bool keep_working(struct worker_pool *pool) |
634 | { |
635 | atomic_t *nr_running = get_pool_nr_running(pool); |
636 | |
637 | return !list_empty(&pool->worklist) && atomic_read(nr_running) <= 1; |
638 | } |
639 | |
640 | /* Do we need a new worker? Called from manager. */ |
641 | static bool need_to_create_worker(struct worker_pool *pool) |
642 | { |
643 | return need_more_worker(pool) && !may_start_working(pool); |
644 | } |
645 | |
646 | /* Do I need to be the manager? */ |
647 | static bool need_to_manage_workers(struct worker_pool *pool) |
648 | { |
649 | return need_to_create_worker(pool) || |
650 | (pool->flags & POOL_MANAGE_WORKERS); |
651 | } |
652 | |
653 | /* Do we have too many workers and should some go away? */ |
654 | static bool too_many_workers(struct worker_pool *pool) |
655 | { |
656 | bool managing = pool->flags & POOL_MANAGING_WORKERS; |
657 | int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ |
658 | int nr_busy = pool->nr_workers - nr_idle; |
659 | |
660 | return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; |
661 | } |
662 | |
663 | /* |
664 | * Wake up functions. |
665 | */ |
666 | |
667 | /* Return the first worker. Safe with preemption disabled */ |
668 | static struct worker *first_worker(struct worker_pool *pool) |
669 | { |
670 | if (unlikely(list_empty(&pool->idle_list))) |
671 | return NULL; |
672 | |
673 | return list_first_entry(&pool->idle_list, struct worker, entry); |
674 | } |
675 | |
676 | /** |
677 | * wake_up_worker - wake up an idle worker |
678 | * @pool: worker pool to wake worker from |
679 | * |
680 | * Wake up the first idle worker of @pool. |
681 | * |
682 | * CONTEXT: |
683 | * spin_lock_irq(gcwq->lock). |
684 | */ |
685 | static void wake_up_worker(struct worker_pool *pool) |
686 | { |
687 | struct worker *worker = first_worker(pool); |
688 | |
689 | if (likely(worker)) |
690 | wake_up_process(worker->task); |
691 | } |
692 | |
693 | /** |
694 | * wq_worker_waking_up - a worker is waking up |
695 | * @task: task waking up |
696 | * @cpu: CPU @task is waking up to |
697 | * |
698 | * This function is called during try_to_wake_up() when a worker is |
699 | * being awoken. |
700 | * |
701 | * CONTEXT: |
702 | * spin_lock_irq(rq->lock) |
703 | */ |
704 | void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) |
705 | { |
706 | struct worker *worker = kthread_data(task); |
707 | |
708 | if (!(worker->flags & WORKER_NOT_RUNNING)) |
709 | atomic_inc(get_pool_nr_running(worker->pool)); |
710 | } |
711 | |
712 | /** |
713 | * wq_worker_sleeping - a worker is going to sleep |
714 | * @task: task going to sleep |
715 | * @cpu: CPU in question, must be the current CPU number |
716 | * |
717 | * This function is called during schedule() when a busy worker is |
718 | * going to sleep. Worker on the same cpu can be woken up by |
719 | * returning pointer to its task. |
720 | * |
721 | * CONTEXT: |
722 | * spin_lock_irq(rq->lock) |
723 | * |
724 | * RETURNS: |
725 | * Worker task on @cpu to wake up, %NULL if none. |
726 | */ |
727 | struct task_struct *wq_worker_sleeping(struct task_struct *task, |
728 | unsigned int cpu) |
729 | { |
730 | struct worker *worker = kthread_data(task), *to_wakeup = NULL; |
731 | struct worker_pool *pool = worker->pool; |
732 | atomic_t *nr_running = get_pool_nr_running(pool); |
733 | |
734 | if (worker->flags & WORKER_NOT_RUNNING) |
735 | return NULL; |
736 | |
737 | /* this can only happen on the local cpu */ |
738 | BUG_ON(cpu != raw_smp_processor_id()); |
739 | |
740 | /* |
741 | * The counterpart of the following dec_and_test, implied mb, |
742 | * worklist not empty test sequence is in insert_work(). |
743 | * Please read comment there. |
744 | * |
745 | * NOT_RUNNING is clear. This means that we're bound to and |
746 | * running on the local cpu w/ rq lock held and preemption |
747 | * disabled, which in turn means that none else could be |
748 | * manipulating idle_list, so dereferencing idle_list without gcwq |
749 | * lock is safe. |
750 | */ |
751 | if (atomic_dec_and_test(nr_running) && !list_empty(&pool->worklist)) |
752 | to_wakeup = first_worker(pool); |
753 | return to_wakeup ? to_wakeup->task : NULL; |
754 | } |
755 | |
756 | /** |
757 | * worker_set_flags - set worker flags and adjust nr_running accordingly |
758 | * @worker: self |
759 | * @flags: flags to set |
760 | * @wakeup: wakeup an idle worker if necessary |
761 | * |
762 | * Set @flags in @worker->flags and adjust nr_running accordingly. If |
763 | * nr_running becomes zero and @wakeup is %true, an idle worker is |
764 | * woken up. |
765 | * |
766 | * CONTEXT: |
767 | * spin_lock_irq(gcwq->lock) |
768 | */ |
769 | static inline void worker_set_flags(struct worker *worker, unsigned int flags, |
770 | bool wakeup) |
771 | { |
772 | struct worker_pool *pool = worker->pool; |
773 | |
774 | WARN_ON_ONCE(worker->task != current); |
775 | |
776 | /* |
777 | * If transitioning into NOT_RUNNING, adjust nr_running and |
778 | * wake up an idle worker as necessary if requested by |
779 | * @wakeup. |
780 | */ |
781 | if ((flags & WORKER_NOT_RUNNING) && |
782 | !(worker->flags & WORKER_NOT_RUNNING)) { |
783 | atomic_t *nr_running = get_pool_nr_running(pool); |
784 | |
785 | if (wakeup) { |
786 | if (atomic_dec_and_test(nr_running) && |
787 | !list_empty(&pool->worklist)) |
788 | wake_up_worker(pool); |
789 | } else |
790 | atomic_dec(nr_running); |
791 | } |
792 | |
793 | worker->flags |= flags; |
794 | } |
795 | |
796 | /** |
797 | * worker_clr_flags - clear worker flags and adjust nr_running accordingly |
798 | * @worker: self |
799 | * @flags: flags to clear |
800 | * |
801 | * Clear @flags in @worker->flags and adjust nr_running accordingly. |
802 | * |
803 | * CONTEXT: |
804 | * spin_lock_irq(gcwq->lock) |
805 | */ |
806 | static inline void worker_clr_flags(struct worker *worker, unsigned int flags) |
807 | { |
808 | struct worker_pool *pool = worker->pool; |
809 | unsigned int oflags = worker->flags; |
810 | |
811 | WARN_ON_ONCE(worker->task != current); |
812 | |
813 | worker->flags &= ~flags; |
814 | |
815 | /* |
816 | * If transitioning out of NOT_RUNNING, increment nr_running. Note |
817 | * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask |
818 | * of multiple flags, not a single flag. |
819 | */ |
820 | if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) |
821 | if (!(worker->flags & WORKER_NOT_RUNNING)) |
822 | atomic_inc(get_pool_nr_running(pool)); |
823 | } |
824 | |
825 | /** |
826 | * busy_worker_head - return the busy hash head for a work |
827 | * @gcwq: gcwq of interest |
828 | * @work: work to be hashed |
829 | * |
830 | * Return hash head of @gcwq for @work. |
831 | * |
832 | * CONTEXT: |
833 | * spin_lock_irq(gcwq->lock). |
834 | * |
835 | * RETURNS: |
836 | * Pointer to the hash head. |
837 | */ |
838 | static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, |
839 | struct work_struct *work) |
840 | { |
841 | const int base_shift = ilog2(sizeof(struct work_struct)); |
842 | unsigned long v = (unsigned long)work; |
843 | |
844 | /* simple shift and fold hash, do we need something better? */ |
845 | v >>= base_shift; |
846 | v += v >> BUSY_WORKER_HASH_ORDER; |
847 | v &= BUSY_WORKER_HASH_MASK; |
848 | |
849 | return &gcwq->busy_hash[v]; |
850 | } |
851 | |
852 | /** |
853 | * __find_worker_executing_work - find worker which is executing a work |
854 | * @gcwq: gcwq of interest |
855 | * @bwh: hash head as returned by busy_worker_head() |
856 | * @work: work to find worker for |
857 | * |
858 | * Find a worker which is executing @work on @gcwq. @bwh should be |
859 | * the hash head obtained by calling busy_worker_head() with the same |
860 | * work. |
861 | * |
862 | * CONTEXT: |
863 | * spin_lock_irq(gcwq->lock). |
864 | * |
865 | * RETURNS: |
866 | * Pointer to worker which is executing @work if found, NULL |
867 | * otherwise. |
868 | */ |
869 | static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, |
870 | struct hlist_head *bwh, |
871 | struct work_struct *work) |
872 | { |
873 | struct worker *worker; |
874 | struct hlist_node *tmp; |
875 | |
876 | hlist_for_each_entry(worker, tmp, bwh, hentry) |
877 | if (worker->current_work == work) |
878 | return worker; |
879 | return NULL; |
880 | } |
881 | |
882 | /** |
883 | * find_worker_executing_work - find worker which is executing a work |
884 | * @gcwq: gcwq of interest |
885 | * @work: work to find worker for |
886 | * |
887 | * Find a worker which is executing @work on @gcwq. This function is |
888 | * identical to __find_worker_executing_work() except that this |
889 | * function calculates @bwh itself. |
890 | * |
891 | * CONTEXT: |
892 | * spin_lock_irq(gcwq->lock). |
893 | * |
894 | * RETURNS: |
895 | * Pointer to worker which is executing @work if found, NULL |
896 | * otherwise. |
897 | */ |
898 | static struct worker *find_worker_executing_work(struct global_cwq *gcwq, |
899 | struct work_struct *work) |
900 | { |
901 | return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), |
902 | work); |
903 | } |
904 | |
905 | /** |
906 | * insert_work - insert a work into gcwq |
907 | * @cwq: cwq @work belongs to |
908 | * @work: work to insert |
909 | * @head: insertion point |
910 | * @extra_flags: extra WORK_STRUCT_* flags to set |
911 | * |
912 | * Insert @work which belongs to @cwq into @gcwq after @head. |
913 | * @extra_flags is or'd to work_struct flags. |
914 | * |
915 | * CONTEXT: |
916 | * spin_lock_irq(gcwq->lock). |
917 | */ |
918 | static void insert_work(struct cpu_workqueue_struct *cwq, |
919 | struct work_struct *work, struct list_head *head, |
920 | unsigned int extra_flags) |
921 | { |
922 | struct worker_pool *pool = cwq->pool; |
923 | |
924 | /* we own @work, set data and link */ |
925 | set_work_cwq(work, cwq, extra_flags); |
926 | |
927 | /* |
928 | * Ensure that we get the right work->data if we see the |
929 | * result of list_add() below, see try_to_grab_pending(). |
930 | */ |
931 | smp_wmb(); |
932 | |
933 | list_add_tail(&work->entry, head); |
934 | |
935 | /* |
936 | * Ensure either worker_sched_deactivated() sees the above |
937 | * list_add_tail() or we see zero nr_running to avoid workers |
938 | * lying around lazily while there are works to be processed. |
939 | */ |
940 | smp_mb(); |
941 | |
942 | if (__need_more_worker(pool)) |
943 | wake_up_worker(pool); |
944 | } |
945 | |
946 | /* |
947 | * Test whether @work is being queued from another work executing on the |
948 | * same workqueue. This is rather expensive and should only be used from |
949 | * cold paths. |
950 | */ |
951 | static bool is_chained_work(struct workqueue_struct *wq) |
952 | { |
953 | unsigned long flags; |
954 | unsigned int cpu; |
955 | |
956 | for_each_gcwq_cpu(cpu) { |
957 | struct global_cwq *gcwq = get_gcwq(cpu); |
958 | struct worker *worker; |
959 | struct hlist_node *pos; |
960 | int i; |
961 | |
962 | spin_lock_irqsave(&gcwq->lock, flags); |
963 | for_each_busy_worker(worker, i, pos, gcwq) { |
964 | if (worker->task != current) |
965 | continue; |
966 | spin_unlock_irqrestore(&gcwq->lock, flags); |
967 | /* |
968 | * I'm @worker, no locking necessary. See if @work |
969 | * is headed to the same workqueue. |
970 | */ |
971 | return worker->current_cwq->wq == wq; |
972 | } |
973 | spin_unlock_irqrestore(&gcwq->lock, flags); |
974 | } |
975 | return false; |
976 | } |
977 | |
978 | static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, |
979 | struct work_struct *work) |
980 | { |
981 | struct global_cwq *gcwq; |
982 | struct cpu_workqueue_struct *cwq; |
983 | struct list_head *worklist; |
984 | unsigned int work_flags; |
985 | unsigned long flags; |
986 | |
987 | debug_work_activate(work); |
988 | |
989 | /* if dying, only works from the same workqueue are allowed */ |
990 | if (unlikely(wq->flags & WQ_DRAINING) && |
991 | WARN_ON_ONCE(!is_chained_work(wq))) |
992 | return; |
993 | |
994 | /* determine gcwq to use */ |
995 | if (!(wq->flags & WQ_UNBOUND)) { |
996 | struct global_cwq *last_gcwq; |
997 | |
998 | if (unlikely(cpu == WORK_CPU_UNBOUND)) |
999 | cpu = raw_smp_processor_id(); |
1000 | |
1001 | /* |
1002 | * It's multi cpu. If @wq is non-reentrant and @work |
1003 | * was previously on a different cpu, it might still |
1004 | * be running there, in which case the work needs to |
1005 | * be queued on that cpu to guarantee non-reentrance. |
1006 | */ |
1007 | gcwq = get_gcwq(cpu); |
1008 | if (wq->flags & WQ_NON_REENTRANT && |
1009 | (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { |
1010 | struct worker *worker; |
1011 | |
1012 | spin_lock_irqsave(&last_gcwq->lock, flags); |
1013 | |
1014 | worker = find_worker_executing_work(last_gcwq, work); |
1015 | |
1016 | if (worker && worker->current_cwq->wq == wq) |
1017 | gcwq = last_gcwq; |
1018 | else { |
1019 | /* meh... not running there, queue here */ |
1020 | spin_unlock_irqrestore(&last_gcwq->lock, flags); |
1021 | spin_lock_irqsave(&gcwq->lock, flags); |
1022 | } |
1023 | } else |
1024 | spin_lock_irqsave(&gcwq->lock, flags); |
1025 | } else { |
1026 | gcwq = get_gcwq(WORK_CPU_UNBOUND); |
1027 | spin_lock_irqsave(&gcwq->lock, flags); |
1028 | } |
1029 | |
1030 | /* gcwq determined, get cwq and queue */ |
1031 | cwq = get_cwq(gcwq->cpu, wq); |
1032 | trace_workqueue_queue_work(cpu, cwq, work); |
1033 | |
1034 | if (WARN_ON(!list_empty(&work->entry))) { |
1035 | spin_unlock_irqrestore(&gcwq->lock, flags); |
1036 | return; |
1037 | } |
1038 | |
1039 | cwq->nr_in_flight[cwq->work_color]++; |
1040 | work_flags = work_color_to_flags(cwq->work_color); |
1041 | |
1042 | if (likely(cwq->nr_active < cwq->max_active)) { |
1043 | trace_workqueue_activate_work(work); |
1044 | cwq->nr_active++; |
1045 | worklist = &cwq->pool->worklist; |
1046 | } else { |
1047 | work_flags |= WORK_STRUCT_DELAYED; |
1048 | worklist = &cwq->delayed_works; |
1049 | } |
1050 | |
1051 | insert_work(cwq, work, worklist, work_flags); |
1052 | |
1053 | spin_unlock_irqrestore(&gcwq->lock, flags); |
1054 | } |
1055 | |
1056 | /** |
1057 | * queue_work - queue work on a workqueue |
1058 | * @wq: workqueue to use |
1059 | * @work: work to queue |
1060 | * |
1061 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1062 | * |
1063 | * We queue the work to the CPU on which it was submitted, but if the CPU dies |
1064 | * it can be processed by another CPU. |
1065 | */ |
1066 | int queue_work(struct workqueue_struct *wq, struct work_struct *work) |
1067 | { |
1068 | int ret; |
1069 | |
1070 | ret = queue_work_on(get_cpu(), wq, work); |
1071 | put_cpu(); |
1072 | |
1073 | return ret; |
1074 | } |
1075 | EXPORT_SYMBOL_GPL(queue_work); |
1076 | |
1077 | /** |
1078 | * queue_work_on - queue work on specific cpu |
1079 | * @cpu: CPU number to execute work on |
1080 | * @wq: workqueue to use |
1081 | * @work: work to queue |
1082 | * |
1083 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1084 | * |
1085 | * We queue the work to a specific CPU, the caller must ensure it |
1086 | * can't go away. |
1087 | */ |
1088 | int |
1089 | queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) |
1090 | { |
1091 | int ret = 0; |
1092 | |
1093 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1094 | __queue_work(cpu, wq, work); |
1095 | ret = 1; |
1096 | } |
1097 | return ret; |
1098 | } |
1099 | EXPORT_SYMBOL_GPL(queue_work_on); |
1100 | |
1101 | static void delayed_work_timer_fn(unsigned long __data) |
1102 | { |
1103 | struct delayed_work *dwork = (struct delayed_work *)__data; |
1104 | struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); |
1105 | |
1106 | __queue_work(smp_processor_id(), cwq->wq, &dwork->work); |
1107 | } |
1108 | |
1109 | /** |
1110 | * queue_delayed_work - queue work on a workqueue after delay |
1111 | * @wq: workqueue to use |
1112 | * @dwork: delayable work to queue |
1113 | * @delay: number of jiffies to wait before queueing |
1114 | * |
1115 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1116 | */ |
1117 | int queue_delayed_work(struct workqueue_struct *wq, |
1118 | struct delayed_work *dwork, unsigned long delay) |
1119 | { |
1120 | if (delay == 0) |
1121 | return queue_work(wq, &dwork->work); |
1122 | |
1123 | return queue_delayed_work_on(-1, wq, dwork, delay); |
1124 | } |
1125 | EXPORT_SYMBOL_GPL(queue_delayed_work); |
1126 | |
1127 | /** |
1128 | * queue_delayed_work_on - queue work on specific CPU after delay |
1129 | * @cpu: CPU number to execute work on |
1130 | * @wq: workqueue to use |
1131 | * @dwork: work to queue |
1132 | * @delay: number of jiffies to wait before queueing |
1133 | * |
1134 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1135 | */ |
1136 | int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
1137 | struct delayed_work *dwork, unsigned long delay) |
1138 | { |
1139 | int ret = 0; |
1140 | struct timer_list *timer = &dwork->timer; |
1141 | struct work_struct *work = &dwork->work; |
1142 | |
1143 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1144 | unsigned int lcpu; |
1145 | |
1146 | BUG_ON(timer_pending(timer)); |
1147 | BUG_ON(!list_empty(&work->entry)); |
1148 | |
1149 | timer_stats_timer_set_start_info(&dwork->timer); |
1150 | |
1151 | /* |
1152 | * This stores cwq for the moment, for the timer_fn. |
1153 | * Note that the work's gcwq is preserved to allow |
1154 | * reentrance detection for delayed works. |
1155 | */ |
1156 | if (!(wq->flags & WQ_UNBOUND)) { |
1157 | struct global_cwq *gcwq = get_work_gcwq(work); |
1158 | |
1159 | if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND) |
1160 | lcpu = gcwq->cpu; |
1161 | else |
1162 | lcpu = raw_smp_processor_id(); |
1163 | } else |
1164 | lcpu = WORK_CPU_UNBOUND; |
1165 | |
1166 | set_work_cwq(work, get_cwq(lcpu, wq), 0); |
1167 | |
1168 | timer->expires = jiffies + delay; |
1169 | timer->data = (unsigned long)dwork; |
1170 | timer->function = delayed_work_timer_fn; |
1171 | |
1172 | if (unlikely(cpu >= 0)) |
1173 | add_timer_on(timer, cpu); |
1174 | else |
1175 | add_timer(timer); |
1176 | ret = 1; |
1177 | } |
1178 | return ret; |
1179 | } |
1180 | EXPORT_SYMBOL_GPL(queue_delayed_work_on); |
1181 | |
1182 | /** |
1183 | * worker_enter_idle - enter idle state |
1184 | * @worker: worker which is entering idle state |
1185 | * |
1186 | * @worker is entering idle state. Update stats and idle timer if |
1187 | * necessary. |
1188 | * |
1189 | * LOCKING: |
1190 | * spin_lock_irq(gcwq->lock). |
1191 | */ |
1192 | static void worker_enter_idle(struct worker *worker) |
1193 | { |
1194 | struct worker_pool *pool = worker->pool; |
1195 | struct global_cwq *gcwq = pool->gcwq; |
1196 | |
1197 | BUG_ON(worker->flags & WORKER_IDLE); |
1198 | BUG_ON(!list_empty(&worker->entry) && |
1199 | (worker->hentry.next || worker->hentry.pprev)); |
1200 | |
1201 | /* can't use worker_set_flags(), also called from start_worker() */ |
1202 | worker->flags |= WORKER_IDLE; |
1203 | pool->nr_idle++; |
1204 | worker->last_active = jiffies; |
1205 | |
1206 | /* idle_list is LIFO */ |
1207 | list_add(&worker->entry, &pool->idle_list); |
1208 | |
1209 | if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) |
1210 | mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); |
1211 | |
1212 | /* |
1213 | * Sanity check nr_running. Because gcwq_unbind_fn() releases |
1214 | * gcwq->lock between setting %WORKER_UNBOUND and zapping |
1215 | * nr_running, the warning may trigger spuriously. Check iff |
1216 | * unbind is not in progress. |
1217 | */ |
1218 | WARN_ON_ONCE(!(gcwq->flags & GCWQ_DISASSOCIATED) && |
1219 | pool->nr_workers == pool->nr_idle && |
1220 | atomic_read(get_pool_nr_running(pool))); |
1221 | } |
1222 | |
1223 | /** |
1224 | * worker_leave_idle - leave idle state |
1225 | * @worker: worker which is leaving idle state |
1226 | * |
1227 | * @worker is leaving idle state. Update stats. |
1228 | * |
1229 | * LOCKING: |
1230 | * spin_lock_irq(gcwq->lock). |
1231 | */ |
1232 | static void worker_leave_idle(struct worker *worker) |
1233 | { |
1234 | struct worker_pool *pool = worker->pool; |
1235 | |
1236 | BUG_ON(!(worker->flags & WORKER_IDLE)); |
1237 | worker_clr_flags(worker, WORKER_IDLE); |
1238 | pool->nr_idle--; |
1239 | list_del_init(&worker->entry); |
1240 | } |
1241 | |
1242 | /** |
1243 | * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq |
1244 | * @worker: self |
1245 | * |
1246 | * Works which are scheduled while the cpu is online must at least be |
1247 | * scheduled to a worker which is bound to the cpu so that if they are |
1248 | * flushed from cpu callbacks while cpu is going down, they are |
1249 | * guaranteed to execute on the cpu. |
1250 | * |
1251 | * This function is to be used by rogue workers and rescuers to bind |
1252 | * themselves to the target cpu and may race with cpu going down or |
1253 | * coming online. kthread_bind() can't be used because it may put the |
1254 | * worker to already dead cpu and set_cpus_allowed_ptr() can't be used |
1255 | * verbatim as it's best effort and blocking and gcwq may be |
1256 | * [dis]associated in the meantime. |
1257 | * |
1258 | * This function tries set_cpus_allowed() and locks gcwq and verifies the |
1259 | * binding against %GCWQ_DISASSOCIATED which is set during |
1260 | * %CPU_DOWN_PREPARE and cleared during %CPU_ONLINE, so if the worker |
1261 | * enters idle state or fetches works without dropping lock, it can |
1262 | * guarantee the scheduling requirement described in the first paragraph. |
1263 | * |
1264 | * CONTEXT: |
1265 | * Might sleep. Called without any lock but returns with gcwq->lock |
1266 | * held. |
1267 | * |
1268 | * RETURNS: |
1269 | * %true if the associated gcwq is online (@worker is successfully |
1270 | * bound), %false if offline. |
1271 | */ |
1272 | static bool worker_maybe_bind_and_lock(struct worker *worker) |
1273 | __acquires(&gcwq->lock) |
1274 | { |
1275 | struct global_cwq *gcwq = worker->pool->gcwq; |
1276 | struct task_struct *task = worker->task; |
1277 | |
1278 | while (true) { |
1279 | /* |
1280 | * The following call may fail, succeed or succeed |
1281 | * without actually migrating the task to the cpu if |
1282 | * it races with cpu hotunplug operation. Verify |
1283 | * against GCWQ_DISASSOCIATED. |
1284 | */ |
1285 | if (!(gcwq->flags & GCWQ_DISASSOCIATED)) |
1286 | set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); |
1287 | |
1288 | spin_lock_irq(&gcwq->lock); |
1289 | if (gcwq->flags & GCWQ_DISASSOCIATED) |
1290 | return false; |
1291 | if (task_cpu(task) == gcwq->cpu && |
1292 | cpumask_equal(¤t->cpus_allowed, |
1293 | get_cpu_mask(gcwq->cpu))) |
1294 | return true; |
1295 | spin_unlock_irq(&gcwq->lock); |
1296 | |
1297 | /* |
1298 | * We've raced with CPU hot[un]plug. Give it a breather |
1299 | * and retry migration. cond_resched() is required here; |
1300 | * otherwise, we might deadlock against cpu_stop trying to |
1301 | * bring down the CPU on non-preemptive kernel. |
1302 | */ |
1303 | cpu_relax(); |
1304 | cond_resched(); |
1305 | } |
1306 | } |
1307 | |
1308 | struct idle_rebind { |
1309 | int cnt; /* # workers to be rebound */ |
1310 | struct completion done; /* all workers rebound */ |
1311 | }; |
1312 | |
1313 | /* |
1314 | * Rebind an idle @worker to its CPU. During CPU onlining, this has to |
1315 | * happen synchronously for idle workers. worker_thread() will test |
1316 | * %WORKER_REBIND before leaving idle and call this function. |
1317 | */ |
1318 | static void idle_worker_rebind(struct worker *worker) |
1319 | { |
1320 | struct global_cwq *gcwq = worker->pool->gcwq; |
1321 | |
1322 | /* CPU must be online at this point */ |
1323 | WARN_ON(!worker_maybe_bind_and_lock(worker)); |
1324 | if (!--worker->idle_rebind->cnt) |
1325 | complete(&worker->idle_rebind->done); |
1326 | spin_unlock_irq(&worker->pool->gcwq->lock); |
1327 | |
1328 | /* we did our part, wait for rebind_workers() to finish up */ |
1329 | wait_event(gcwq->rebind_hold, !(worker->flags & WORKER_REBIND)); |
1330 | |
1331 | /* |
1332 | * rebind_workers() shouldn't finish until all workers passed the |
1333 | * above WORKER_REBIND wait. Tell it when done. |
1334 | */ |
1335 | spin_lock_irq(&worker->pool->gcwq->lock); |
1336 | if (!--worker->idle_rebind->cnt) |
1337 | complete(&worker->idle_rebind->done); |
1338 | spin_unlock_irq(&worker->pool->gcwq->lock); |
1339 | } |
1340 | |
1341 | /* |
1342 | * Function for @worker->rebind.work used to rebind unbound busy workers to |
1343 | * the associated cpu which is coming back online. This is scheduled by |
1344 | * cpu up but can race with other cpu hotplug operations and may be |
1345 | * executed twice without intervening cpu down. |
1346 | */ |
1347 | static void busy_worker_rebind_fn(struct work_struct *work) |
1348 | { |
1349 | struct worker *worker = container_of(work, struct worker, rebind_work); |
1350 | struct global_cwq *gcwq = worker->pool->gcwq; |
1351 | |
1352 | worker_maybe_bind_and_lock(worker); |
1353 | |
1354 | /* |
1355 | * %WORKER_REBIND must be cleared even if the above binding failed; |
1356 | * otherwise, we may confuse the next CPU_UP cycle or oops / get |
1357 | * stuck by calling idle_worker_rebind() prematurely. If CPU went |
1358 | * down again inbetween, %WORKER_UNBOUND would be set, so clearing |
1359 | * %WORKER_REBIND is always safe. |
1360 | */ |
1361 | worker_clr_flags(worker, WORKER_REBIND); |
1362 | |
1363 | spin_unlock_irq(&gcwq->lock); |
1364 | } |
1365 | |
1366 | /** |
1367 | * rebind_workers - rebind all workers of a gcwq to the associated CPU |
1368 | * @gcwq: gcwq of interest |
1369 | * |
1370 | * @gcwq->cpu is coming online. Rebind all workers to the CPU. Rebinding |
1371 | * is different for idle and busy ones. |
1372 | * |
1373 | * The idle ones should be rebound synchronously and idle rebinding should |
1374 | * be complete before any worker starts executing work items with |
1375 | * concurrency management enabled; otherwise, scheduler may oops trying to |
1376 | * wake up non-local idle worker from wq_worker_sleeping(). |
1377 | * |
1378 | * This is achieved by repeatedly requesting rebinding until all idle |
1379 | * workers are known to have been rebound under @gcwq->lock and holding all |
1380 | * idle workers from becoming busy until idle rebinding is complete. |
1381 | * |
1382 | * Once idle workers are rebound, busy workers can be rebound as they |
1383 | * finish executing their current work items. Queueing the rebind work at |
1384 | * the head of their scheduled lists is enough. Note that nr_running will |
1385 | * be properbly bumped as busy workers rebind. |
1386 | * |
1387 | * On return, all workers are guaranteed to either be bound or have rebind |
1388 | * work item scheduled. |
1389 | */ |
1390 | static void rebind_workers(struct global_cwq *gcwq) |
1391 | __releases(&gcwq->lock) __acquires(&gcwq->lock) |
1392 | { |
1393 | struct idle_rebind idle_rebind; |
1394 | struct worker_pool *pool; |
1395 | struct worker *worker; |
1396 | struct hlist_node *pos; |
1397 | int i; |
1398 | |
1399 | lockdep_assert_held(&gcwq->lock); |
1400 | |
1401 | for_each_worker_pool(pool, gcwq) |
1402 | lockdep_assert_held(&pool->manager_mutex); |
1403 | |
1404 | /* |
1405 | * Rebind idle workers. Interlocked both ways. We wait for |
1406 | * workers to rebind via @idle_rebind.done. Workers will wait for |
1407 | * us to finish up by watching %WORKER_REBIND. |
1408 | */ |
1409 | init_completion(&idle_rebind.done); |
1410 | retry: |
1411 | idle_rebind.cnt = 1; |
1412 | INIT_COMPLETION(idle_rebind.done); |
1413 | |
1414 | /* set REBIND and kick idle ones, we'll wait for these later */ |
1415 | for_each_worker_pool(pool, gcwq) { |
1416 | list_for_each_entry(worker, &pool->idle_list, entry) { |
1417 | unsigned long worker_flags = worker->flags; |
1418 | |
1419 | if (worker->flags & WORKER_REBIND) |
1420 | continue; |
1421 | |
1422 | /* morph UNBOUND to REBIND atomically */ |
1423 | worker_flags &= ~WORKER_UNBOUND; |
1424 | worker_flags |= WORKER_REBIND; |
1425 | ACCESS_ONCE(worker->flags) = worker_flags; |
1426 | |
1427 | idle_rebind.cnt++; |
1428 | worker->idle_rebind = &idle_rebind; |
1429 | |
1430 | /* worker_thread() will call idle_worker_rebind() */ |
1431 | wake_up_process(worker->task); |
1432 | } |
1433 | } |
1434 | |
1435 | if (--idle_rebind.cnt) { |
1436 | spin_unlock_irq(&gcwq->lock); |
1437 | wait_for_completion(&idle_rebind.done); |
1438 | spin_lock_irq(&gcwq->lock); |
1439 | /* busy ones might have become idle while waiting, retry */ |
1440 | goto retry; |
1441 | } |
1442 | |
1443 | /* all idle workers are rebound, rebind busy workers */ |
1444 | for_each_busy_worker(worker, i, pos, gcwq) { |
1445 | struct work_struct *rebind_work = &worker->rebind_work; |
1446 | unsigned long worker_flags = worker->flags; |
1447 | |
1448 | /* morph UNBOUND to REBIND atomically */ |
1449 | worker_flags &= ~WORKER_UNBOUND; |
1450 | worker_flags |= WORKER_REBIND; |
1451 | ACCESS_ONCE(worker->flags) = worker_flags; |
1452 | |
1453 | if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, |
1454 | work_data_bits(rebind_work))) |
1455 | continue; |
1456 | |
1457 | /* wq doesn't matter, use the default one */ |
1458 | debug_work_activate(rebind_work); |
1459 | insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work, |
1460 | worker->scheduled.next, |
1461 | work_color_to_flags(WORK_NO_COLOR)); |
1462 | } |
1463 | |
1464 | /* |
1465 | * All idle workers are rebound and waiting for %WORKER_REBIND to |
1466 | * be cleared inside idle_worker_rebind(). Clear and release. |
1467 | * Clearing %WORKER_REBIND from this foreign context is safe |
1468 | * because these workers are still guaranteed to be idle. |
1469 | * |
1470 | * We need to make sure all idle workers passed WORKER_REBIND wait |
1471 | * in idle_worker_rebind() before returning; otherwise, workers can |
1472 | * get stuck at the wait if hotplug cycle repeats. |
1473 | */ |
1474 | idle_rebind.cnt = 1; |
1475 | INIT_COMPLETION(idle_rebind.done); |
1476 | |
1477 | for_each_worker_pool(pool, gcwq) { |
1478 | list_for_each_entry(worker, &pool->idle_list, entry) { |
1479 | worker->flags &= ~WORKER_REBIND; |
1480 | idle_rebind.cnt++; |
1481 | } |
1482 | } |
1483 | |
1484 | wake_up_all(&gcwq->rebind_hold); |
1485 | |
1486 | if (--idle_rebind.cnt) { |
1487 | spin_unlock_irq(&gcwq->lock); |
1488 | wait_for_completion(&idle_rebind.done); |
1489 | spin_lock_irq(&gcwq->lock); |
1490 | } |
1491 | } |
1492 | |
1493 | static struct worker *alloc_worker(void) |
1494 | { |
1495 | struct worker *worker; |
1496 | |
1497 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); |
1498 | if (worker) { |
1499 | INIT_LIST_HEAD(&worker->entry); |
1500 | INIT_LIST_HEAD(&worker->scheduled); |
1501 | INIT_WORK(&worker->rebind_work, busy_worker_rebind_fn); |
1502 | /* on creation a worker is in !idle && prep state */ |
1503 | worker->flags = WORKER_PREP; |
1504 | } |
1505 | return worker; |
1506 | } |
1507 | |
1508 | /** |
1509 | * create_worker - create a new workqueue worker |
1510 | * @pool: pool the new worker will belong to |
1511 | * |
1512 | * Create a new worker which is bound to @pool. The returned worker |
1513 | * can be started by calling start_worker() or destroyed using |
1514 | * destroy_worker(). |
1515 | * |
1516 | * CONTEXT: |
1517 | * Might sleep. Does GFP_KERNEL allocations. |
1518 | * |
1519 | * RETURNS: |
1520 | * Pointer to the newly created worker. |
1521 | */ |
1522 | static struct worker *create_worker(struct worker_pool *pool) |
1523 | { |
1524 | struct global_cwq *gcwq = pool->gcwq; |
1525 | const char *pri = worker_pool_pri(pool) ? "H" : ""; |
1526 | struct worker *worker = NULL; |
1527 | int id = -1; |
1528 | |
1529 | spin_lock_irq(&gcwq->lock); |
1530 | while (ida_get_new(&pool->worker_ida, &id)) { |
1531 | spin_unlock_irq(&gcwq->lock); |
1532 | if (!ida_pre_get(&pool->worker_ida, GFP_KERNEL)) |
1533 | goto fail; |
1534 | spin_lock_irq(&gcwq->lock); |
1535 | } |
1536 | spin_unlock_irq(&gcwq->lock); |
1537 | |
1538 | worker = alloc_worker(); |
1539 | if (!worker) |
1540 | goto fail; |
1541 | |
1542 | worker->pool = pool; |
1543 | worker->id = id; |
1544 | |
1545 | if (gcwq->cpu != WORK_CPU_UNBOUND) |
1546 | worker->task = kthread_create_on_node(worker_thread, |
1547 | worker, cpu_to_node(gcwq->cpu), |
1548 | "kworker/%u:%d%s", gcwq->cpu, id, pri); |
1549 | else |
1550 | worker->task = kthread_create(worker_thread, worker, |
1551 | "kworker/u:%d%s", id, pri); |
1552 | if (IS_ERR(worker->task)) |
1553 | goto fail; |
1554 | |
1555 | if (worker_pool_pri(pool)) |
1556 | set_user_nice(worker->task, HIGHPRI_NICE_LEVEL); |
1557 | |
1558 | /* |
1559 | * Determine CPU binding of the new worker depending on |
1560 | * %GCWQ_DISASSOCIATED. The caller is responsible for ensuring the |
1561 | * flag remains stable across this function. See the comments |
1562 | * above the flag definition for details. |
1563 | * |
1564 | * As an unbound worker may later become a regular one if CPU comes |
1565 | * online, make sure every worker has %PF_THREAD_BOUND set. |
1566 | */ |
1567 | if (!(gcwq->flags & GCWQ_DISASSOCIATED)) { |
1568 | kthread_bind(worker->task, gcwq->cpu); |
1569 | } else { |
1570 | worker->task->flags |= PF_THREAD_BOUND; |
1571 | worker->flags |= WORKER_UNBOUND; |
1572 | } |
1573 | |
1574 | return worker; |
1575 | fail: |
1576 | if (id >= 0) { |
1577 | spin_lock_irq(&gcwq->lock); |
1578 | ida_remove(&pool->worker_ida, id); |
1579 | spin_unlock_irq(&gcwq->lock); |
1580 | } |
1581 | kfree(worker); |
1582 | return NULL; |
1583 | } |
1584 | |
1585 | /** |
1586 | * start_worker - start a newly created worker |
1587 | * @worker: worker to start |
1588 | * |
1589 | * Make the gcwq aware of @worker and start it. |
1590 | * |
1591 | * CONTEXT: |
1592 | * spin_lock_irq(gcwq->lock). |
1593 | */ |
1594 | static void start_worker(struct worker *worker) |
1595 | { |
1596 | worker->flags |= WORKER_STARTED; |
1597 | worker->pool->nr_workers++; |
1598 | worker_enter_idle(worker); |
1599 | wake_up_process(worker->task); |
1600 | } |
1601 | |
1602 | /** |
1603 | * destroy_worker - destroy a workqueue worker |
1604 | * @worker: worker to be destroyed |
1605 | * |
1606 | * Destroy @worker and adjust @gcwq stats accordingly. |
1607 | * |
1608 | * CONTEXT: |
1609 | * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
1610 | */ |
1611 | static void destroy_worker(struct worker *worker) |
1612 | { |
1613 | struct worker_pool *pool = worker->pool; |
1614 | struct global_cwq *gcwq = pool->gcwq; |
1615 | int id = worker->id; |
1616 | |
1617 | /* sanity check frenzy */ |
1618 | BUG_ON(worker->current_work); |
1619 | BUG_ON(!list_empty(&worker->scheduled)); |
1620 | |
1621 | if (worker->flags & WORKER_STARTED) |
1622 | pool->nr_workers--; |
1623 | if (worker->flags & WORKER_IDLE) |
1624 | pool->nr_idle--; |
1625 | |
1626 | list_del_init(&worker->entry); |
1627 | worker->flags |= WORKER_DIE; |
1628 | |
1629 | spin_unlock_irq(&gcwq->lock); |
1630 | |
1631 | kthread_stop(worker->task); |
1632 | kfree(worker); |
1633 | |
1634 | spin_lock_irq(&gcwq->lock); |
1635 | ida_remove(&pool->worker_ida, id); |
1636 | } |
1637 | |
1638 | static void idle_worker_timeout(unsigned long __pool) |
1639 | { |
1640 | struct worker_pool *pool = (void *)__pool; |
1641 | struct global_cwq *gcwq = pool->gcwq; |
1642 | |
1643 | spin_lock_irq(&gcwq->lock); |
1644 | |
1645 | if (too_many_workers(pool)) { |
1646 | struct worker *worker; |
1647 | unsigned long expires; |
1648 | |
1649 | /* idle_list is kept in LIFO order, check the last one */ |
1650 | worker = list_entry(pool->idle_list.prev, struct worker, entry); |
1651 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
1652 | |
1653 | if (time_before(jiffies, expires)) |
1654 | mod_timer(&pool->idle_timer, expires); |
1655 | else { |
1656 | /* it's been idle for too long, wake up manager */ |
1657 | pool->flags |= POOL_MANAGE_WORKERS; |
1658 | wake_up_worker(pool); |
1659 | } |
1660 | } |
1661 | |
1662 | spin_unlock_irq(&gcwq->lock); |
1663 | } |
1664 | |
1665 | static bool send_mayday(struct work_struct *work) |
1666 | { |
1667 | struct cpu_workqueue_struct *cwq = get_work_cwq(work); |
1668 | struct workqueue_struct *wq = cwq->wq; |
1669 | unsigned int cpu; |
1670 | |
1671 | if (!(wq->flags & WQ_RESCUER)) |
1672 | return false; |
1673 | |
1674 | /* mayday mayday mayday */ |
1675 | cpu = cwq->pool->gcwq->cpu; |
1676 | /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ |
1677 | if (cpu == WORK_CPU_UNBOUND) |
1678 | cpu = 0; |
1679 | if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) |
1680 | wake_up_process(wq->rescuer->task); |
1681 | return true; |
1682 | } |
1683 | |
1684 | static void gcwq_mayday_timeout(unsigned long __pool) |
1685 | { |
1686 | struct worker_pool *pool = (void *)__pool; |
1687 | struct global_cwq *gcwq = pool->gcwq; |
1688 | struct work_struct *work; |
1689 | |
1690 | spin_lock_irq(&gcwq->lock); |
1691 | |
1692 | if (need_to_create_worker(pool)) { |
1693 | /* |
1694 | * We've been trying to create a new worker but |
1695 | * haven't been successful. We might be hitting an |
1696 | * allocation deadlock. Send distress signals to |
1697 | * rescuers. |
1698 | */ |
1699 | list_for_each_entry(work, &pool->worklist, entry) |
1700 | send_mayday(work); |
1701 | } |
1702 | |
1703 | spin_unlock_irq(&gcwq->lock); |
1704 | |
1705 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); |
1706 | } |
1707 | |
1708 | /** |
1709 | * maybe_create_worker - create a new worker if necessary |
1710 | * @pool: pool to create a new worker for |
1711 | * |
1712 | * Create a new worker for @pool if necessary. @pool is guaranteed to |
1713 | * have at least one idle worker on return from this function. If |
1714 | * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is |
1715 | * sent to all rescuers with works scheduled on @pool to resolve |
1716 | * possible allocation deadlock. |
1717 | * |
1718 | * On return, need_to_create_worker() is guaranteed to be false and |
1719 | * may_start_working() true. |
1720 | * |
1721 | * LOCKING: |
1722 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
1723 | * multiple times. Does GFP_KERNEL allocations. Called only from |
1724 | * manager. |
1725 | * |
1726 | * RETURNS: |
1727 | * false if no action was taken and gcwq->lock stayed locked, true |
1728 | * otherwise. |
1729 | */ |
1730 | static bool maybe_create_worker(struct worker_pool *pool) |
1731 | __releases(&gcwq->lock) |
1732 | __acquires(&gcwq->lock) |
1733 | { |
1734 | struct global_cwq *gcwq = pool->gcwq; |
1735 | |
1736 | if (!need_to_create_worker(pool)) |
1737 | return false; |
1738 | restart: |
1739 | spin_unlock_irq(&gcwq->lock); |
1740 | |
1741 | /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ |
1742 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); |
1743 | |
1744 | while (true) { |
1745 | struct worker *worker; |
1746 | |
1747 | worker = create_worker(pool); |
1748 | if (worker) { |
1749 | del_timer_sync(&pool->mayday_timer); |
1750 | spin_lock_irq(&gcwq->lock); |
1751 | start_worker(worker); |
1752 | BUG_ON(need_to_create_worker(pool)); |
1753 | return true; |
1754 | } |
1755 | |
1756 | if (!need_to_create_worker(pool)) |
1757 | break; |
1758 | |
1759 | __set_current_state(TASK_INTERRUPTIBLE); |
1760 | schedule_timeout(CREATE_COOLDOWN); |
1761 | |
1762 | if (!need_to_create_worker(pool)) |
1763 | break; |
1764 | } |
1765 | |
1766 | del_timer_sync(&pool->mayday_timer); |
1767 | spin_lock_irq(&gcwq->lock); |
1768 | if (need_to_create_worker(pool)) |
1769 | goto restart; |
1770 | return true; |
1771 | } |
1772 | |
1773 | /** |
1774 | * maybe_destroy_worker - destroy workers which have been idle for a while |
1775 | * @pool: pool to destroy workers for |
1776 | * |
1777 | * Destroy @pool workers which have been idle for longer than |
1778 | * IDLE_WORKER_TIMEOUT. |
1779 | * |
1780 | * LOCKING: |
1781 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
1782 | * multiple times. Called only from manager. |
1783 | * |
1784 | * RETURNS: |
1785 | * false if no action was taken and gcwq->lock stayed locked, true |
1786 | * otherwise. |
1787 | */ |
1788 | static bool maybe_destroy_workers(struct worker_pool *pool) |
1789 | { |
1790 | bool ret = false; |
1791 | |
1792 | while (too_many_workers(pool)) { |
1793 | struct worker *worker; |
1794 | unsigned long expires; |
1795 | |
1796 | worker = list_entry(pool->idle_list.prev, struct worker, entry); |
1797 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
1798 | |
1799 | if (time_before(jiffies, expires)) { |
1800 | mod_timer(&pool->idle_timer, expires); |
1801 | break; |
1802 | } |
1803 | |
1804 | destroy_worker(worker); |
1805 | ret = true; |
1806 | } |
1807 | |
1808 | return ret; |
1809 | } |
1810 | |
1811 | /** |
1812 | * manage_workers - manage worker pool |
1813 | * @worker: self |
1814 | * |
1815 | * Assume the manager role and manage gcwq worker pool @worker belongs |
1816 | * to. At any given time, there can be only zero or one manager per |
1817 | * gcwq. The exclusion is handled automatically by this function. |
1818 | * |
1819 | * The caller can safely start processing works on false return. On |
1820 | * true return, it's guaranteed that need_to_create_worker() is false |
1821 | * and may_start_working() is true. |
1822 | * |
1823 | * CONTEXT: |
1824 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
1825 | * multiple times. Does GFP_KERNEL allocations. |
1826 | * |
1827 | * RETURNS: |
1828 | * false if no action was taken and gcwq->lock stayed locked, true if |
1829 | * some action was taken. |
1830 | */ |
1831 | static bool manage_workers(struct worker *worker) |
1832 | { |
1833 | struct worker_pool *pool = worker->pool; |
1834 | bool ret = false; |
1835 | |
1836 | if (pool->flags & POOL_MANAGING_WORKERS) |
1837 | return ret; |
1838 | |
1839 | pool->flags |= POOL_MANAGING_WORKERS; |
1840 | |
1841 | /* |
1842 | * To simplify both worker management and CPU hotplug, hold off |
1843 | * management while hotplug is in progress. CPU hotplug path can't |
1844 | * grab %POOL_MANAGING_WORKERS to achieve this because that can |
1845 | * lead to idle worker depletion (all become busy thinking someone |
1846 | * else is managing) which in turn can result in deadlock under |
1847 | * extreme circumstances. Use @pool->manager_mutex to synchronize |
1848 | * manager against CPU hotplug. |
1849 | * |
1850 | * manager_mutex would always be free unless CPU hotplug is in |
1851 | * progress. trylock first without dropping @gcwq->lock. |
1852 | */ |
1853 | if (unlikely(!mutex_trylock(&pool->manager_mutex))) { |
1854 | spin_unlock_irq(&pool->gcwq->lock); |
1855 | mutex_lock(&pool->manager_mutex); |
1856 | /* |
1857 | * CPU hotplug could have happened while we were waiting |
1858 | * for manager_mutex. Hotplug itself can't handle us |
1859 | * because manager isn't either on idle or busy list, and |
1860 | * @gcwq's state and ours could have deviated. |
1861 | * |
1862 | * As hotplug is now excluded via manager_mutex, we can |
1863 | * simply try to bind. It will succeed or fail depending |
1864 | * on @gcwq's current state. Try it and adjust |
1865 | * %WORKER_UNBOUND accordingly. |
1866 | */ |
1867 | if (worker_maybe_bind_and_lock(worker)) |
1868 | worker->flags &= ~WORKER_UNBOUND; |
1869 | else |
1870 | worker->flags |= WORKER_UNBOUND; |
1871 | |
1872 | ret = true; |
1873 | } |
1874 | |
1875 | pool->flags &= ~POOL_MANAGE_WORKERS; |
1876 | |
1877 | /* |
1878 | * Destroy and then create so that may_start_working() is true |
1879 | * on return. |
1880 | */ |
1881 | ret |= maybe_destroy_workers(pool); |
1882 | ret |= maybe_create_worker(pool); |
1883 | |
1884 | pool->flags &= ~POOL_MANAGING_WORKERS; |
1885 | mutex_unlock(&pool->manager_mutex); |
1886 | return ret; |
1887 | } |
1888 | |
1889 | /** |
1890 | * move_linked_works - move linked works to a list |
1891 | * @work: start of series of works to be scheduled |
1892 | * @head: target list to append @work to |
1893 | * @nextp: out paramter for nested worklist walking |
1894 | * |
1895 | * Schedule linked works starting from @work to @head. Work series to |
1896 | * be scheduled starts at @work and includes any consecutive work with |
1897 | * WORK_STRUCT_LINKED set in its predecessor. |
1898 | * |
1899 | * If @nextp is not NULL, it's updated to point to the next work of |
1900 | * the last scheduled work. This allows move_linked_works() to be |
1901 | * nested inside outer list_for_each_entry_safe(). |
1902 | * |
1903 | * CONTEXT: |
1904 | * spin_lock_irq(gcwq->lock). |
1905 | */ |
1906 | static void move_linked_works(struct work_struct *work, struct list_head *head, |
1907 | struct work_struct **nextp) |
1908 | { |
1909 | struct work_struct *n; |
1910 | |
1911 | /* |
1912 | * Linked worklist will always end before the end of the list, |
1913 | * use NULL for list head. |
1914 | */ |
1915 | list_for_each_entry_safe_from(work, n, NULL, entry) { |
1916 | list_move_tail(&work->entry, head); |
1917 | if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) |
1918 | break; |
1919 | } |
1920 | |
1921 | /* |
1922 | * If we're already inside safe list traversal and have moved |
1923 | * multiple works to the scheduled queue, the next position |
1924 | * needs to be updated. |
1925 | */ |
1926 | if (nextp) |
1927 | *nextp = n; |
1928 | } |
1929 | |
1930 | static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) |
1931 | { |
1932 | struct work_struct *work = list_first_entry(&cwq->delayed_works, |
1933 | struct work_struct, entry); |
1934 | |
1935 | trace_workqueue_activate_work(work); |
1936 | move_linked_works(work, &cwq->pool->worklist, NULL); |
1937 | __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); |
1938 | cwq->nr_active++; |
1939 | } |
1940 | |
1941 | /** |
1942 | * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight |
1943 | * @cwq: cwq of interest |
1944 | * @color: color of work which left the queue |
1945 | * @delayed: for a delayed work |
1946 | * |
1947 | * A work either has completed or is removed from pending queue, |
1948 | * decrement nr_in_flight of its cwq and handle workqueue flushing. |
1949 | * |
1950 | * CONTEXT: |
1951 | * spin_lock_irq(gcwq->lock). |
1952 | */ |
1953 | static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color, |
1954 | bool delayed) |
1955 | { |
1956 | /* ignore uncolored works */ |
1957 | if (color == WORK_NO_COLOR) |
1958 | return; |
1959 | |
1960 | cwq->nr_in_flight[color]--; |
1961 | |
1962 | if (!delayed) { |
1963 | cwq->nr_active--; |
1964 | if (!list_empty(&cwq->delayed_works)) { |
1965 | /* one down, submit a delayed one */ |
1966 | if (cwq->nr_active < cwq->max_active) |
1967 | cwq_activate_first_delayed(cwq); |
1968 | } |
1969 | } |
1970 | |
1971 | /* is flush in progress and are we at the flushing tip? */ |
1972 | if (likely(cwq->flush_color != color)) |
1973 | return; |
1974 | |
1975 | /* are there still in-flight works? */ |
1976 | if (cwq->nr_in_flight[color]) |
1977 | return; |
1978 | |
1979 | /* this cwq is done, clear flush_color */ |
1980 | cwq->flush_color = -1; |
1981 | |
1982 | /* |
1983 | * If this was the last cwq, wake up the first flusher. It |
1984 | * will handle the rest. |
1985 | */ |
1986 | if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) |
1987 | complete(&cwq->wq->first_flusher->done); |
1988 | } |
1989 | |
1990 | /** |
1991 | * process_one_work - process single work |
1992 | * @worker: self |
1993 | * @work: work to process |
1994 | * |
1995 | * Process @work. This function contains all the logics necessary to |
1996 | * process a single work including synchronization against and |
1997 | * interaction with other workers on the same cpu, queueing and |
1998 | * flushing. As long as context requirement is met, any worker can |
1999 | * call this function to process a work. |
2000 | * |
2001 | * CONTEXT: |
2002 | * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
2003 | */ |
2004 | static void process_one_work(struct worker *worker, struct work_struct *work) |
2005 | __releases(&gcwq->lock) |
2006 | __acquires(&gcwq->lock) |
2007 | { |
2008 | struct cpu_workqueue_struct *cwq = get_work_cwq(work); |
2009 | struct worker_pool *pool = worker->pool; |
2010 | struct global_cwq *gcwq = pool->gcwq; |
2011 | struct hlist_head *bwh = busy_worker_head(gcwq, work); |
2012 | bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; |
2013 | work_func_t f = work->func; |
2014 | int work_color; |
2015 | struct worker *collision; |
2016 | #ifdef CONFIG_LOCKDEP |
2017 | /* |
2018 | * It is permissible to free the struct work_struct from |
2019 | * inside the function that is called from it, this we need to |
2020 | * take into account for lockdep too. To avoid bogus "held |
2021 | * lock freed" warnings as well as problems when looking into |
2022 | * work->lockdep_map, make a copy and use that here. |
2023 | */ |
2024 | struct lockdep_map lockdep_map; |
2025 | |
2026 | lockdep_copy_map(&lockdep_map, &work->lockdep_map); |
2027 | #endif |
2028 | /* |
2029 | * Ensure we're on the correct CPU. DISASSOCIATED test is |
2030 | * necessary to avoid spurious warnings from rescuers servicing the |
2031 | * unbound or a disassociated gcwq. |
2032 | */ |
2033 | WARN_ON_ONCE(!(worker->flags & (WORKER_UNBOUND | WORKER_REBIND)) && |
2034 | !(gcwq->flags & GCWQ_DISASSOCIATED) && |
2035 | raw_smp_processor_id() != gcwq->cpu); |
2036 | |
2037 | /* |
2038 | * A single work shouldn't be executed concurrently by |
2039 | * multiple workers on a single cpu. Check whether anyone is |
2040 | * already processing the work. If so, defer the work to the |
2041 | * currently executing one. |
2042 | */ |
2043 | collision = __find_worker_executing_work(gcwq, bwh, work); |
2044 | if (unlikely(collision)) { |
2045 | move_linked_works(work, &collision->scheduled, NULL); |
2046 | return; |
2047 | } |
2048 | |
2049 | /* claim and process */ |
2050 | debug_work_deactivate(work); |
2051 | hlist_add_head(&worker->hentry, bwh); |
2052 | worker->current_work = work; |
2053 | worker->current_cwq = cwq; |
2054 | work_color = get_work_color(work); |
2055 | |
2056 | /* record the current cpu number in the work data and dequeue */ |
2057 | set_work_cpu(work, gcwq->cpu); |
2058 | list_del_init(&work->entry); |
2059 | |
2060 | /* |
2061 | * CPU intensive works don't participate in concurrency |
2062 | * management. They're the scheduler's responsibility. |
2063 | */ |
2064 | if (unlikely(cpu_intensive)) |
2065 | worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); |
2066 | |
2067 | /* |
2068 | * Unbound gcwq isn't concurrency managed and work items should be |
2069 | * executed ASAP. Wake up another worker if necessary. |
2070 | */ |
2071 | if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) |
2072 | wake_up_worker(pool); |
2073 | |
2074 | spin_unlock_irq(&gcwq->lock); |
2075 | |
2076 | work_clear_pending(work); |
2077 | lock_map_acquire_read(&cwq->wq->lockdep_map); |
2078 | lock_map_acquire(&lockdep_map); |
2079 | trace_workqueue_execute_start(work); |
2080 | f(work); |
2081 | /* |
2082 | * While we must be careful to not use "work" after this, the trace |
2083 | * point will only record its address. |
2084 | */ |
2085 | trace_workqueue_execute_end(work); |
2086 | lock_map_release(&lockdep_map); |
2087 | lock_map_release(&cwq->wq->lockdep_map); |
2088 | |
2089 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { |
2090 | printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " |
2091 | "%s/0x%08x/%d\n", |
2092 | current->comm, preempt_count(), task_pid_nr(current)); |
2093 | printk(KERN_ERR " last function: "); |
2094 | print_symbol("%s\n", (unsigned long)f); |
2095 | debug_show_held_locks(current); |
2096 | dump_stack(); |
2097 | } |
2098 | |
2099 | spin_lock_irq(&gcwq->lock); |
2100 | |
2101 | /* clear cpu intensive status */ |
2102 | if (unlikely(cpu_intensive)) |
2103 | worker_clr_flags(worker, WORKER_CPU_INTENSIVE); |
2104 | |
2105 | /* we're done with it, release */ |
2106 | hlist_del_init(&worker->hentry); |
2107 | worker->current_work = NULL; |
2108 | worker->current_cwq = NULL; |
2109 | cwq_dec_nr_in_flight(cwq, work_color, false); |
2110 | } |
2111 | |
2112 | /** |
2113 | * process_scheduled_works - process scheduled works |
2114 | * @worker: self |
2115 | * |
2116 | * Process all scheduled works. Please note that the scheduled list |
2117 | * may change while processing a work, so this function repeatedly |
2118 | * fetches a work from the top and executes it. |
2119 | * |
2120 | * CONTEXT: |
2121 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
2122 | * multiple times. |
2123 | */ |
2124 | static void process_scheduled_works(struct worker *worker) |
2125 | { |
2126 | while (!list_empty(&worker->scheduled)) { |
2127 | struct work_struct *work = list_first_entry(&worker->scheduled, |
2128 | struct work_struct, entry); |
2129 | process_one_work(worker, work); |
2130 | } |
2131 | } |
2132 | |
2133 | /** |
2134 | * worker_thread - the worker thread function |
2135 | * @__worker: self |
2136 | * |
2137 | * The gcwq worker thread function. There's a single dynamic pool of |
2138 | * these per each cpu. These workers process all works regardless of |
2139 | * their specific target workqueue. The only exception is works which |
2140 | * belong to workqueues with a rescuer which will be explained in |
2141 | * rescuer_thread(). |
2142 | */ |
2143 | static int worker_thread(void *__worker) |
2144 | { |
2145 | struct worker *worker = __worker; |
2146 | struct worker_pool *pool = worker->pool; |
2147 | struct global_cwq *gcwq = pool->gcwq; |
2148 | |
2149 | /* tell the scheduler that this is a workqueue worker */ |
2150 | worker->task->flags |= PF_WQ_WORKER; |
2151 | woke_up: |
2152 | spin_lock_irq(&gcwq->lock); |
2153 | |
2154 | /* |
2155 | * DIE can be set only while idle and REBIND set while busy has |
2156 | * @worker->rebind_work scheduled. Checking here is enough. |
2157 | */ |
2158 | if (unlikely(worker->flags & (WORKER_REBIND | WORKER_DIE))) { |
2159 | spin_unlock_irq(&gcwq->lock); |
2160 | |
2161 | if (worker->flags & WORKER_DIE) { |
2162 | worker->task->flags &= ~PF_WQ_WORKER; |
2163 | return 0; |
2164 | } |
2165 | |
2166 | idle_worker_rebind(worker); |
2167 | goto woke_up; |
2168 | } |
2169 | |
2170 | worker_leave_idle(worker); |
2171 | recheck: |
2172 | /* no more worker necessary? */ |
2173 | if (!need_more_worker(pool)) |
2174 | goto sleep; |
2175 | |
2176 | /* do we need to manage? */ |
2177 | if (unlikely(!may_start_working(pool)) && manage_workers(worker)) |
2178 | goto recheck; |
2179 | |
2180 | /* |
2181 | * ->scheduled list can only be filled while a worker is |
2182 | * preparing to process a work or actually processing it. |
2183 | * Make sure nobody diddled with it while I was sleeping. |
2184 | */ |
2185 | BUG_ON(!list_empty(&worker->scheduled)); |
2186 | |
2187 | /* |
2188 | * When control reaches this point, we're guaranteed to have |
2189 | * at least one idle worker or that someone else has already |
2190 | * assumed the manager role. |
2191 | */ |
2192 | worker_clr_flags(worker, WORKER_PREP); |
2193 | |
2194 | do { |
2195 | struct work_struct *work = |
2196 | list_first_entry(&pool->worklist, |
2197 | struct work_struct, entry); |
2198 | |
2199 | if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { |
2200 | /* optimization path, not strictly necessary */ |
2201 | process_one_work(worker, work); |
2202 | if (unlikely(!list_empty(&worker->scheduled))) |
2203 | process_scheduled_works(worker); |
2204 | } else { |
2205 | move_linked_works(work, &worker->scheduled, NULL); |
2206 | process_scheduled_works(worker); |
2207 | } |
2208 | } while (keep_working(pool)); |
2209 | |
2210 | worker_set_flags(worker, WORKER_PREP, false); |
2211 | sleep: |
2212 | if (unlikely(need_to_manage_workers(pool)) && manage_workers(worker)) |
2213 | goto recheck; |
2214 | |
2215 | /* |
2216 | * gcwq->lock is held and there's no work to process and no |
2217 | * need to manage, sleep. Workers are woken up only while |
2218 | * holding gcwq->lock or from local cpu, so setting the |
2219 | * current state before releasing gcwq->lock is enough to |
2220 | * prevent losing any event. |
2221 | */ |
2222 | worker_enter_idle(worker); |
2223 | __set_current_state(TASK_INTERRUPTIBLE); |
2224 | spin_unlock_irq(&gcwq->lock); |
2225 | schedule(); |
2226 | goto woke_up; |
2227 | } |
2228 | |
2229 | /** |
2230 | * rescuer_thread - the rescuer thread function |
2231 | * @__wq: the associated workqueue |
2232 | * |
2233 | * Workqueue rescuer thread function. There's one rescuer for each |
2234 | * workqueue which has WQ_RESCUER set. |
2235 | * |
2236 | * Regular work processing on a gcwq may block trying to create a new |
2237 | * worker which uses GFP_KERNEL allocation which has slight chance of |
2238 | * developing into deadlock if some works currently on the same queue |
2239 | * need to be processed to satisfy the GFP_KERNEL allocation. This is |
2240 | * the problem rescuer solves. |
2241 | * |
2242 | * When such condition is possible, the gcwq summons rescuers of all |
2243 | * workqueues which have works queued on the gcwq and let them process |
2244 | * those works so that forward progress can be guaranteed. |
2245 | * |
2246 | * This should happen rarely. |
2247 | */ |
2248 | static int rescuer_thread(void *__wq) |
2249 | { |
2250 | struct workqueue_struct *wq = __wq; |
2251 | struct worker *rescuer = wq->rescuer; |
2252 | struct list_head *scheduled = &rescuer->scheduled; |
2253 | bool is_unbound = wq->flags & WQ_UNBOUND; |
2254 | unsigned int cpu; |
2255 | |
2256 | set_user_nice(current, RESCUER_NICE_LEVEL); |
2257 | repeat: |
2258 | set_current_state(TASK_INTERRUPTIBLE); |
2259 | |
2260 | if (kthread_should_stop()) |
2261 | return 0; |
2262 | |
2263 | /* |
2264 | * See whether any cpu is asking for help. Unbounded |
2265 | * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. |
2266 | */ |
2267 | for_each_mayday_cpu(cpu, wq->mayday_mask) { |
2268 | unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; |
2269 | struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); |
2270 | struct worker_pool *pool = cwq->pool; |
2271 | struct global_cwq *gcwq = pool->gcwq; |
2272 | struct work_struct *work, *n; |
2273 | |
2274 | __set_current_state(TASK_RUNNING); |
2275 | mayday_clear_cpu(cpu, wq->mayday_mask); |
2276 | |
2277 | /* migrate to the target cpu if possible */ |
2278 | rescuer->pool = pool; |
2279 | worker_maybe_bind_and_lock(rescuer); |
2280 | |
2281 | /* |
2282 | * Slurp in all works issued via this workqueue and |
2283 | * process'em. |
2284 | */ |
2285 | BUG_ON(!list_empty(&rescuer->scheduled)); |
2286 | list_for_each_entry_safe(work, n, &pool->worklist, entry) |
2287 | if (get_work_cwq(work) == cwq) |
2288 | move_linked_works(work, scheduled, &n); |
2289 | |
2290 | process_scheduled_works(rescuer); |
2291 | |
2292 | /* |
2293 | * Leave this gcwq. If keep_working() is %true, notify a |
2294 | * regular worker; otherwise, we end up with 0 concurrency |
2295 | * and stalling the execution. |
2296 | */ |
2297 | if (keep_working(pool)) |
2298 | wake_up_worker(pool); |
2299 | |
2300 | spin_unlock_irq(&gcwq->lock); |
2301 | } |
2302 | |
2303 | schedule(); |
2304 | goto repeat; |
2305 | } |
2306 | |
2307 | struct wq_barrier { |
2308 | struct work_struct work; |
2309 | struct completion done; |
2310 | }; |
2311 | |
2312 | static void wq_barrier_func(struct work_struct *work) |
2313 | { |
2314 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); |
2315 | complete(&barr->done); |
2316 | } |
2317 | |
2318 | /** |
2319 | * insert_wq_barrier - insert a barrier work |
2320 | * @cwq: cwq to insert barrier into |
2321 | * @barr: wq_barrier to insert |
2322 | * @target: target work to attach @barr to |
2323 | * @worker: worker currently executing @target, NULL if @target is not executing |
2324 | * |
2325 | * @barr is linked to @target such that @barr is completed only after |
2326 | * @target finishes execution. Please note that the ordering |
2327 | * guarantee is observed only with respect to @target and on the local |
2328 | * cpu. |
2329 | * |
2330 | * Currently, a queued barrier can't be canceled. This is because |
2331 | * try_to_grab_pending() can't determine whether the work to be |
2332 | * grabbed is at the head of the queue and thus can't clear LINKED |
2333 | * flag of the previous work while there must be a valid next work |
2334 | * after a work with LINKED flag set. |
2335 | * |
2336 | * Note that when @worker is non-NULL, @target may be modified |
2337 | * underneath us, so we can't reliably determine cwq from @target. |
2338 | * |
2339 | * CONTEXT: |
2340 | * spin_lock_irq(gcwq->lock). |
2341 | */ |
2342 | static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, |
2343 | struct wq_barrier *barr, |
2344 | struct work_struct *target, struct worker *worker) |
2345 | { |
2346 | struct list_head *head; |
2347 | unsigned int linked = 0; |
2348 | |
2349 | /* |
2350 | * debugobject calls are safe here even with gcwq->lock locked |
2351 | * as we know for sure that this will not trigger any of the |
2352 | * checks and call back into the fixup functions where we |
2353 | * might deadlock. |
2354 | */ |
2355 | INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); |
2356 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
2357 | init_completion(&barr->done); |
2358 | |
2359 | /* |
2360 | * If @target is currently being executed, schedule the |
2361 | * barrier to the worker; otherwise, put it after @target. |
2362 | */ |
2363 | if (worker) |
2364 | head = worker->scheduled.next; |
2365 | else { |
2366 | unsigned long *bits = work_data_bits(target); |
2367 | |
2368 | head = target->entry.next; |
2369 | /* there can already be other linked works, inherit and set */ |
2370 | linked = *bits & WORK_STRUCT_LINKED; |
2371 | __set_bit(WORK_STRUCT_LINKED_BIT, bits); |
2372 | } |
2373 | |
2374 | debug_work_activate(&barr->work); |
2375 | insert_work(cwq, &barr->work, head, |
2376 | work_color_to_flags(WORK_NO_COLOR) | linked); |
2377 | } |
2378 | |
2379 | /** |
2380 | * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing |
2381 | * @wq: workqueue being flushed |
2382 | * @flush_color: new flush color, < 0 for no-op |
2383 | * @work_color: new work color, < 0 for no-op |
2384 | * |
2385 | * Prepare cwqs for workqueue flushing. |
2386 | * |
2387 | * If @flush_color is non-negative, flush_color on all cwqs should be |
2388 | * -1. If no cwq has in-flight commands at the specified color, all |
2389 | * cwq->flush_color's stay at -1 and %false is returned. If any cwq |
2390 | * has in flight commands, its cwq->flush_color is set to |
2391 | * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq |
2392 | * wakeup logic is armed and %true is returned. |
2393 | * |
2394 | * The caller should have initialized @wq->first_flusher prior to |
2395 | * calling this function with non-negative @flush_color. If |
2396 | * @flush_color is negative, no flush color update is done and %false |
2397 | * is returned. |
2398 | * |
2399 | * If @work_color is non-negative, all cwqs should have the same |
2400 | * work_color which is previous to @work_color and all will be |
2401 | * advanced to @work_color. |
2402 | * |
2403 | * CONTEXT: |
2404 | * mutex_lock(wq->flush_mutex). |
2405 | * |
2406 | * RETURNS: |
2407 | * %true if @flush_color >= 0 and there's something to flush. %false |
2408 | * otherwise. |
2409 | */ |
2410 | static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, |
2411 | int flush_color, int work_color) |
2412 | { |
2413 | bool wait = false; |
2414 | unsigned int cpu; |
2415 | |
2416 | if (flush_color >= 0) { |
2417 | BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); |
2418 | atomic_set(&wq->nr_cwqs_to_flush, 1); |
2419 | } |
2420 | |
2421 | for_each_cwq_cpu(cpu, wq) { |
2422 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
2423 | struct global_cwq *gcwq = cwq->pool->gcwq; |
2424 | |
2425 | spin_lock_irq(&gcwq->lock); |
2426 | |
2427 | if (flush_color >= 0) { |
2428 | BUG_ON(cwq->flush_color != -1); |
2429 | |
2430 | if (cwq->nr_in_flight[flush_color]) { |
2431 | cwq->flush_color = flush_color; |
2432 | atomic_inc(&wq->nr_cwqs_to_flush); |
2433 | wait = true; |
2434 | } |
2435 | } |
2436 | |
2437 | if (work_color >= 0) { |
2438 | BUG_ON(work_color != work_next_color(cwq->work_color)); |
2439 | cwq->work_color = work_color; |
2440 | } |
2441 | |
2442 | spin_unlock_irq(&gcwq->lock); |
2443 | } |
2444 | |
2445 | if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) |
2446 | complete(&wq->first_flusher->done); |
2447 | |
2448 | return wait; |
2449 | } |
2450 | |
2451 | /** |
2452 | * flush_workqueue - ensure that any scheduled work has run to completion. |
2453 | * @wq: workqueue to flush |
2454 | * |
2455 | * Forces execution of the workqueue and blocks until its completion. |
2456 | * This is typically used in driver shutdown handlers. |
2457 | * |
2458 | * We sleep until all works which were queued on entry have been handled, |
2459 | * but we are not livelocked by new incoming ones. |
2460 | */ |
2461 | void flush_workqueue(struct workqueue_struct *wq) |
2462 | { |
2463 | struct wq_flusher this_flusher = { |
2464 | .list = LIST_HEAD_INIT(this_flusher.list), |
2465 | .flush_color = -1, |
2466 | .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), |
2467 | }; |
2468 | int next_color; |
2469 | |
2470 | lock_map_acquire(&wq->lockdep_map); |
2471 | lock_map_release(&wq->lockdep_map); |
2472 | |
2473 | mutex_lock(&wq->flush_mutex); |
2474 | |
2475 | /* |
2476 | * Start-to-wait phase |
2477 | */ |
2478 | next_color = work_next_color(wq->work_color); |
2479 | |
2480 | if (next_color != wq->flush_color) { |
2481 | /* |
2482 | * Color space is not full. The current work_color |
2483 | * becomes our flush_color and work_color is advanced |
2484 | * by one. |
2485 | */ |
2486 | BUG_ON(!list_empty(&wq->flusher_overflow)); |
2487 | this_flusher.flush_color = wq->work_color; |
2488 | wq->work_color = next_color; |
2489 | |
2490 | if (!wq->first_flusher) { |
2491 | /* no flush in progress, become the first flusher */ |
2492 | BUG_ON(wq->flush_color != this_flusher.flush_color); |
2493 | |
2494 | wq->first_flusher = &this_flusher; |
2495 | |
2496 | if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, |
2497 | wq->work_color)) { |
2498 | /* nothing to flush, done */ |
2499 | wq->flush_color = next_color; |
2500 | wq->first_flusher = NULL; |
2501 | goto out_unlock; |
2502 | } |
2503 | } else { |
2504 | /* wait in queue */ |
2505 | BUG_ON(wq->flush_color == this_flusher.flush_color); |
2506 | list_add_tail(&this_flusher.list, &wq->flusher_queue); |
2507 | flush_workqueue_prep_cwqs(wq, -1, wq->work_color); |
2508 | } |
2509 | } else { |
2510 | /* |
2511 | * Oops, color space is full, wait on overflow queue. |
2512 | * The next flush completion will assign us |
2513 | * flush_color and transfer to flusher_queue. |
2514 | */ |
2515 | list_add_tail(&this_flusher.list, &wq->flusher_overflow); |
2516 | } |
2517 | |
2518 | mutex_unlock(&wq->flush_mutex); |
2519 | |
2520 | wait_for_completion(&this_flusher.done); |
2521 | |
2522 | /* |
2523 | * Wake-up-and-cascade phase |
2524 | * |
2525 | * First flushers are responsible for cascading flushes and |
2526 | * handling overflow. Non-first flushers can simply return. |
2527 | */ |
2528 | if (wq->first_flusher != &this_flusher) |
2529 | return; |
2530 | |
2531 | mutex_lock(&wq->flush_mutex); |
2532 | |
2533 | /* we might have raced, check again with mutex held */ |
2534 | if (wq->first_flusher != &this_flusher) |
2535 | goto out_unlock; |
2536 | |
2537 | wq->first_flusher = NULL; |
2538 | |
2539 | BUG_ON(!list_empty(&this_flusher.list)); |
2540 | BUG_ON(wq->flush_color != this_flusher.flush_color); |
2541 | |
2542 | while (true) { |
2543 | struct wq_flusher *next, *tmp; |
2544 | |
2545 | /* complete all the flushers sharing the current flush color */ |
2546 | list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { |
2547 | if (next->flush_color != wq->flush_color) |
2548 | break; |
2549 | list_del_init(&next->list); |
2550 | complete(&next->done); |
2551 | } |
2552 | |
2553 | BUG_ON(!list_empty(&wq->flusher_overflow) && |
2554 | wq->flush_color != work_next_color(wq->work_color)); |
2555 | |
2556 | /* this flush_color is finished, advance by one */ |
2557 | wq->flush_color = work_next_color(wq->flush_color); |
2558 | |
2559 | /* one color has been freed, handle overflow queue */ |
2560 | if (!list_empty(&wq->flusher_overflow)) { |
2561 | /* |
2562 | * Assign the same color to all overflowed |
2563 | * flushers, advance work_color and append to |
2564 | * flusher_queue. This is the start-to-wait |
2565 | * phase for these overflowed flushers. |
2566 | */ |
2567 | list_for_each_entry(tmp, &wq->flusher_overflow, list) |
2568 | tmp->flush_color = wq->work_color; |
2569 | |
2570 | wq->work_color = work_next_color(wq->work_color); |
2571 | |
2572 | list_splice_tail_init(&wq->flusher_overflow, |
2573 | &wq->flusher_queue); |
2574 | flush_workqueue_prep_cwqs(wq, -1, wq->work_color); |
2575 | } |
2576 | |
2577 | if (list_empty(&wq->flusher_queue)) { |
2578 | BUG_ON(wq->flush_color != wq->work_color); |
2579 | break; |
2580 | } |
2581 | |
2582 | /* |
2583 | * Need to flush more colors. Make the next flusher |
2584 | * the new first flusher and arm cwqs. |
2585 | */ |
2586 | BUG_ON(wq->flush_color == wq->work_color); |
2587 | BUG_ON(wq->flush_color != next->flush_color); |
2588 | |
2589 | list_del_init(&next->list); |
2590 | wq->first_flusher = next; |
2591 | |
2592 | if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) |
2593 | break; |
2594 | |
2595 | /* |
2596 | * Meh... this color is already done, clear first |
2597 | * flusher and repeat cascading. |
2598 | */ |
2599 | wq->first_flusher = NULL; |
2600 | } |
2601 | |
2602 | out_unlock: |
2603 | mutex_unlock(&wq->flush_mutex); |
2604 | } |
2605 | EXPORT_SYMBOL_GPL(flush_workqueue); |
2606 | |
2607 | /** |
2608 | * drain_workqueue - drain a workqueue |
2609 | * @wq: workqueue to drain |
2610 | * |
2611 | * Wait until the workqueue becomes empty. While draining is in progress, |
2612 | * only chain queueing is allowed. IOW, only currently pending or running |
2613 | * work items on @wq can queue further work items on it. @wq is flushed |
2614 | * repeatedly until it becomes empty. The number of flushing is detemined |
2615 | * by the depth of chaining and should be relatively short. Whine if it |
2616 | * takes too long. |
2617 | */ |
2618 | void drain_workqueue(struct workqueue_struct *wq) |
2619 | { |
2620 | unsigned int flush_cnt = 0; |
2621 | unsigned int cpu; |
2622 | |
2623 | /* |
2624 | * __queue_work() needs to test whether there are drainers, is much |
2625 | * hotter than drain_workqueue() and already looks at @wq->flags. |
2626 | * Use WQ_DRAINING so that queue doesn't have to check nr_drainers. |
2627 | */ |
2628 | spin_lock(&workqueue_lock); |
2629 | if (!wq->nr_drainers++) |
2630 | wq->flags |= WQ_DRAINING; |
2631 | spin_unlock(&workqueue_lock); |
2632 | reflush: |
2633 | flush_workqueue(wq); |
2634 | |
2635 | for_each_cwq_cpu(cpu, wq) { |
2636 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
2637 | bool drained; |
2638 | |
2639 | spin_lock_irq(&cwq->pool->gcwq->lock); |
2640 | drained = !cwq->nr_active && list_empty(&cwq->delayed_works); |
2641 | spin_unlock_irq(&cwq->pool->gcwq->lock); |
2642 | |
2643 | if (drained) |
2644 | continue; |
2645 | |
2646 | if (++flush_cnt == 10 || |
2647 | (flush_cnt % 100 == 0 && flush_cnt <= 1000)) |
2648 | pr_warning("workqueue %s: flush on destruction isn't complete after %u tries\n", |
2649 | wq->name, flush_cnt); |
2650 | goto reflush; |
2651 | } |
2652 | |
2653 | spin_lock(&workqueue_lock); |
2654 | if (!--wq->nr_drainers) |
2655 | wq->flags &= ~WQ_DRAINING; |
2656 | spin_unlock(&workqueue_lock); |
2657 | } |
2658 | EXPORT_SYMBOL_GPL(drain_workqueue); |
2659 | |
2660 | static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr, |
2661 | bool wait_executing) |
2662 | { |
2663 | struct worker *worker = NULL; |
2664 | struct global_cwq *gcwq; |
2665 | struct cpu_workqueue_struct *cwq; |
2666 | |
2667 | might_sleep(); |
2668 | gcwq = get_work_gcwq(work); |
2669 | if (!gcwq) |
2670 | return false; |
2671 | |
2672 | spin_lock_irq(&gcwq->lock); |
2673 | if (!list_empty(&work->entry)) { |
2674 | /* |
2675 | * See the comment near try_to_grab_pending()->smp_rmb(). |
2676 | * If it was re-queued to a different gcwq under us, we |
2677 | * are not going to wait. |
2678 | */ |
2679 | smp_rmb(); |
2680 | cwq = get_work_cwq(work); |
2681 | if (unlikely(!cwq || gcwq != cwq->pool->gcwq)) |
2682 | goto already_gone; |
2683 | } else if (wait_executing) { |
2684 | worker = find_worker_executing_work(gcwq, work); |
2685 | if (!worker) |
2686 | goto already_gone; |
2687 | cwq = worker->current_cwq; |
2688 | } else |
2689 | goto already_gone; |
2690 | |
2691 | insert_wq_barrier(cwq, barr, work, worker); |
2692 | spin_unlock_irq(&gcwq->lock); |
2693 | |
2694 | /* |
2695 | * If @max_active is 1 or rescuer is in use, flushing another work |
2696 | * item on the same workqueue may lead to deadlock. Make sure the |
2697 | * flusher is not running on the same workqueue by verifying write |
2698 | * access. |
2699 | */ |
2700 | if (cwq->wq->saved_max_active == 1 || cwq->wq->flags & WQ_RESCUER) |
2701 | lock_map_acquire(&cwq->wq->lockdep_map); |
2702 | else |
2703 | lock_map_acquire_read(&cwq->wq->lockdep_map); |
2704 | lock_map_release(&cwq->wq->lockdep_map); |
2705 | |
2706 | return true; |
2707 | already_gone: |
2708 | spin_unlock_irq(&gcwq->lock); |
2709 | return false; |
2710 | } |
2711 | |
2712 | /** |
2713 | * flush_work - wait for a work to finish executing the last queueing instance |
2714 | * @work: the work to flush |
2715 | * |
2716 | * Wait until @work has finished execution. This function considers |
2717 | * only the last queueing instance of @work. If @work has been |
2718 | * enqueued across different CPUs on a non-reentrant workqueue or on |
2719 | * multiple workqueues, @work might still be executing on return on |
2720 | * some of the CPUs from earlier queueing. |
2721 | * |
2722 | * If @work was queued only on a non-reentrant, ordered or unbound |
2723 | * workqueue, @work is guaranteed to be idle on return if it hasn't |
2724 | * been requeued since flush started. |
2725 | * |
2726 | * RETURNS: |
2727 | * %true if flush_work() waited for the work to finish execution, |
2728 | * %false if it was already idle. |
2729 | */ |
2730 | bool flush_work(struct work_struct *work) |
2731 | { |
2732 | struct wq_barrier barr; |
2733 | |
2734 | lock_map_acquire(&work->lockdep_map); |
2735 | lock_map_release(&work->lockdep_map); |
2736 | |
2737 | if (start_flush_work(work, &barr, true)) { |
2738 | wait_for_completion(&barr.done); |
2739 | destroy_work_on_stack(&barr.work); |
2740 | return true; |
2741 | } else |
2742 | return false; |
2743 | } |
2744 | EXPORT_SYMBOL_GPL(flush_work); |
2745 | |
2746 | static bool wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) |
2747 | { |
2748 | struct wq_barrier barr; |
2749 | struct worker *worker; |
2750 | |
2751 | spin_lock_irq(&gcwq->lock); |
2752 | |
2753 | worker = find_worker_executing_work(gcwq, work); |
2754 | if (unlikely(worker)) |
2755 | insert_wq_barrier(worker->current_cwq, &barr, work, worker); |
2756 | |
2757 | spin_unlock_irq(&gcwq->lock); |
2758 | |
2759 | if (unlikely(worker)) { |
2760 | wait_for_completion(&barr.done); |
2761 | destroy_work_on_stack(&barr.work); |
2762 | return true; |
2763 | } else |
2764 | return false; |
2765 | } |
2766 | |
2767 | static bool wait_on_work(struct work_struct *work) |
2768 | { |
2769 | bool ret = false; |
2770 | int cpu; |
2771 | |
2772 | might_sleep(); |
2773 | |
2774 | lock_map_acquire(&work->lockdep_map); |
2775 | lock_map_release(&work->lockdep_map); |
2776 | |
2777 | for_each_gcwq_cpu(cpu) |
2778 | ret |= wait_on_cpu_work(get_gcwq(cpu), work); |
2779 | return ret; |
2780 | } |
2781 | |
2782 | /** |
2783 | * flush_work_sync - wait until a work has finished execution |
2784 | * @work: the work to flush |
2785 | * |
2786 | * Wait until @work has finished execution. On return, it's |
2787 | * guaranteed that all queueing instances of @work which happened |
2788 | * before this function is called are finished. In other words, if |
2789 | * @work hasn't been requeued since this function was called, @work is |
2790 | * guaranteed to be idle on return. |
2791 | * |
2792 | * RETURNS: |
2793 | * %true if flush_work_sync() waited for the work to finish execution, |
2794 | * %false if it was already idle. |
2795 | */ |
2796 | bool flush_work_sync(struct work_struct *work) |
2797 | { |
2798 | struct wq_barrier barr; |
2799 | bool pending, waited; |
2800 | |
2801 | /* we'll wait for executions separately, queue barr only if pending */ |
2802 | pending = start_flush_work(work, &barr, false); |
2803 | |
2804 | /* wait for executions to finish */ |
2805 | waited = wait_on_work(work); |
2806 | |
2807 | /* wait for the pending one */ |
2808 | if (pending) { |
2809 | wait_for_completion(&barr.done); |
2810 | destroy_work_on_stack(&barr.work); |
2811 | } |
2812 | |
2813 | return pending || waited; |
2814 | } |
2815 | EXPORT_SYMBOL_GPL(flush_work_sync); |
2816 | |
2817 | /* |
2818 | * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, |
2819 | * so this work can't be re-armed in any way. |
2820 | */ |
2821 | static int try_to_grab_pending(struct work_struct *work) |
2822 | { |
2823 | struct global_cwq *gcwq; |
2824 | int ret = -1; |
2825 | |
2826 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
2827 | return 0; |
2828 | |
2829 | /* |
2830 | * The queueing is in progress, or it is already queued. Try to |
2831 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. |
2832 | */ |
2833 | gcwq = get_work_gcwq(work); |
2834 | if (!gcwq) |
2835 | return ret; |
2836 | |
2837 | spin_lock_irq(&gcwq->lock); |
2838 | if (!list_empty(&work->entry)) { |
2839 | /* |
2840 | * This work is queued, but perhaps we locked the wrong gcwq. |
2841 | * In that case we must see the new value after rmb(), see |
2842 | * insert_work()->wmb(). |
2843 | */ |
2844 | smp_rmb(); |
2845 | if (gcwq == get_work_gcwq(work)) { |
2846 | debug_work_deactivate(work); |
2847 | list_del_init(&work->entry); |
2848 | cwq_dec_nr_in_flight(get_work_cwq(work), |
2849 | get_work_color(work), |
2850 | *work_data_bits(work) & WORK_STRUCT_DELAYED); |
2851 | ret = 1; |
2852 | } |
2853 | } |
2854 | spin_unlock_irq(&gcwq->lock); |
2855 | |
2856 | return ret; |
2857 | } |
2858 | |
2859 | static bool __cancel_work_timer(struct work_struct *work, |
2860 | struct timer_list* timer) |
2861 | { |
2862 | int ret; |
2863 | |
2864 | do { |
2865 | ret = (timer && likely(del_timer(timer))); |
2866 | if (!ret) |
2867 | ret = try_to_grab_pending(work); |
2868 | wait_on_work(work); |
2869 | } while (unlikely(ret < 0)); |
2870 | |
2871 | clear_work_data(work); |
2872 | return ret; |
2873 | } |
2874 | |
2875 | /** |
2876 | * cancel_work_sync - cancel a work and wait for it to finish |
2877 | * @work: the work to cancel |
2878 | * |
2879 | * Cancel @work and wait for its execution to finish. This function |
2880 | * can be used even if the work re-queues itself or migrates to |
2881 | * another workqueue. On return from this function, @work is |
2882 | * guaranteed to be not pending or executing on any CPU. |
2883 | * |
2884 | * cancel_work_sync(&delayed_work->work) must not be used for |
2885 | * delayed_work's. Use cancel_delayed_work_sync() instead. |
2886 | * |
2887 | * The caller must ensure that the workqueue on which @work was last |
2888 | * queued can't be destroyed before this function returns. |
2889 | * |
2890 | * RETURNS: |
2891 | * %true if @work was pending, %false otherwise. |
2892 | */ |
2893 | bool cancel_work_sync(struct work_struct *work) |
2894 | { |
2895 | return __cancel_work_timer(work, NULL); |
2896 | } |
2897 | EXPORT_SYMBOL_GPL(cancel_work_sync); |
2898 | |
2899 | /** |
2900 | * flush_delayed_work - wait for a dwork to finish executing the last queueing |
2901 | * @dwork: the delayed work to flush |
2902 | * |
2903 | * Delayed timer is cancelled and the pending work is queued for |
2904 | * immediate execution. Like flush_work(), this function only |
2905 | * considers the last queueing instance of @dwork. |
2906 | * |
2907 | * RETURNS: |
2908 | * %true if flush_work() waited for the work to finish execution, |
2909 | * %false if it was already idle. |
2910 | */ |
2911 | bool flush_delayed_work(struct delayed_work *dwork) |
2912 | { |
2913 | if (del_timer_sync(&dwork->timer)) |
2914 | __queue_work(raw_smp_processor_id(), |
2915 | get_work_cwq(&dwork->work)->wq, &dwork->work); |
2916 | return flush_work(&dwork->work); |
2917 | } |
2918 | EXPORT_SYMBOL(flush_delayed_work); |
2919 | |
2920 | /** |
2921 | * flush_delayed_work_sync - wait for a dwork to finish |
2922 | * @dwork: the delayed work to flush |
2923 | * |
2924 | * Delayed timer is cancelled and the pending work is queued for |
2925 | * execution immediately. Other than timer handling, its behavior |
2926 | * is identical to flush_work_sync(). |
2927 | * |
2928 | * RETURNS: |
2929 | * %true if flush_work_sync() waited for the work to finish execution, |
2930 | * %false if it was already idle. |
2931 | */ |
2932 | bool flush_delayed_work_sync(struct delayed_work *dwork) |
2933 | { |
2934 | if (del_timer_sync(&dwork->timer)) |
2935 | __queue_work(raw_smp_processor_id(), |
2936 | get_work_cwq(&dwork->work)->wq, &dwork->work); |
2937 | return flush_work_sync(&dwork->work); |
2938 | } |
2939 | EXPORT_SYMBOL(flush_delayed_work_sync); |
2940 | |
2941 | /** |
2942 | * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish |
2943 | * @dwork: the delayed work cancel |
2944 | * |
2945 | * This is cancel_work_sync() for delayed works. |
2946 | * |
2947 | * RETURNS: |
2948 | * %true if @dwork was pending, %false otherwise. |
2949 | */ |
2950 | bool cancel_delayed_work_sync(struct delayed_work *dwork) |
2951 | { |
2952 | return __cancel_work_timer(&dwork->work, &dwork->timer); |
2953 | } |
2954 | EXPORT_SYMBOL(cancel_delayed_work_sync); |
2955 | |
2956 | /** |
2957 | * schedule_work - put work task in global workqueue |
2958 | * @work: job to be done |
2959 | * |
2960 | * Returns zero if @work was already on the kernel-global workqueue and |
2961 | * non-zero otherwise. |
2962 | * |
2963 | * This puts a job in the kernel-global workqueue if it was not already |
2964 | * queued and leaves it in the same position on the kernel-global |
2965 | * workqueue otherwise. |
2966 | */ |
2967 | int schedule_work(struct work_struct *work) |
2968 | { |
2969 | return queue_work(system_wq, work); |
2970 | } |
2971 | EXPORT_SYMBOL(schedule_work); |
2972 | |
2973 | /* |
2974 | * schedule_work_on - put work task on a specific cpu |
2975 | * @cpu: cpu to put the work task on |
2976 | * @work: job to be done |
2977 | * |
2978 | * This puts a job on a specific cpu |
2979 | */ |
2980 | int schedule_work_on(int cpu, struct work_struct *work) |
2981 | { |
2982 | return queue_work_on(cpu, system_wq, work); |
2983 | } |
2984 | EXPORT_SYMBOL(schedule_work_on); |
2985 | |
2986 | /** |
2987 | * schedule_delayed_work - put work task in global workqueue after delay |
2988 | * @dwork: job to be done |
2989 | * @delay: number of jiffies to wait or 0 for immediate execution |
2990 | * |
2991 | * After waiting for a given time this puts a job in the kernel-global |
2992 | * workqueue. |
2993 | */ |
2994 | int schedule_delayed_work(struct delayed_work *dwork, |
2995 | unsigned long delay) |
2996 | { |
2997 | return queue_delayed_work(system_wq, dwork, delay); |
2998 | } |
2999 | EXPORT_SYMBOL(schedule_delayed_work); |
3000 | |
3001 | /** |
3002 | * schedule_delayed_work_on - queue work in global workqueue on CPU after delay |
3003 | * @cpu: cpu to use |
3004 | * @dwork: job to be done |
3005 | * @delay: number of jiffies to wait |
3006 | * |
3007 | * After waiting for a given time this puts a job in the kernel-global |
3008 | * workqueue on the specified CPU. |
3009 | */ |
3010 | int schedule_delayed_work_on(int cpu, |
3011 | struct delayed_work *dwork, unsigned long delay) |
3012 | { |
3013 | return queue_delayed_work_on(cpu, system_wq, dwork, delay); |
3014 | } |
3015 | EXPORT_SYMBOL(schedule_delayed_work_on); |
3016 | |
3017 | /** |
3018 | * schedule_on_each_cpu - execute a function synchronously on each online CPU |
3019 | * @func: the function to call |
3020 | * |
3021 | * schedule_on_each_cpu() executes @func on each online CPU using the |
3022 | * system workqueue and blocks until all CPUs have completed. |
3023 | * schedule_on_each_cpu() is very slow. |
3024 | * |
3025 | * RETURNS: |
3026 | * 0 on success, -errno on failure. |
3027 | */ |
3028 | int schedule_on_each_cpu(work_func_t func) |
3029 | { |
3030 | int cpu; |
3031 | struct work_struct __percpu *works; |
3032 | |
3033 | works = alloc_percpu(struct work_struct); |
3034 | if (!works) |
3035 | return -ENOMEM; |
3036 | |
3037 | get_online_cpus(); |
3038 | |
3039 | for_each_online_cpu(cpu) { |
3040 | struct work_struct *work = per_cpu_ptr(works, cpu); |
3041 | |
3042 | INIT_WORK(work, func); |
3043 | schedule_work_on(cpu, work); |
3044 | } |
3045 | |
3046 | for_each_online_cpu(cpu) |
3047 | flush_work(per_cpu_ptr(works, cpu)); |
3048 | |
3049 | put_online_cpus(); |
3050 | free_percpu(works); |
3051 | return 0; |
3052 | } |
3053 | |
3054 | /** |
3055 | * flush_scheduled_work - ensure that any scheduled work has run to completion. |
3056 | * |
3057 | * Forces execution of the kernel-global workqueue and blocks until its |
3058 | * completion. |
3059 | * |
3060 | * Think twice before calling this function! It's very easy to get into |
3061 | * trouble if you don't take great care. Either of the following situations |
3062 | * will lead to deadlock: |
3063 | * |
3064 | * One of the work items currently on the workqueue needs to acquire |
3065 | * a lock held by your code or its caller. |
3066 | * |
3067 | * Your code is running in the context of a work routine. |
3068 | * |
3069 | * They will be detected by lockdep when they occur, but the first might not |
3070 | * occur very often. It depends on what work items are on the workqueue and |
3071 | * what locks they need, which you have no control over. |
3072 | * |
3073 | * In most situations flushing the entire workqueue is overkill; you merely |
3074 | * need to know that a particular work item isn't queued and isn't running. |
3075 | * In such cases you should use cancel_delayed_work_sync() or |
3076 | * cancel_work_sync() instead. |
3077 | */ |
3078 | void flush_scheduled_work(void) |
3079 | { |
3080 | flush_workqueue(system_wq); |
3081 | } |
3082 | EXPORT_SYMBOL(flush_scheduled_work); |
3083 | |
3084 | /** |
3085 | * execute_in_process_context - reliably execute the routine with user context |
3086 | * @fn: the function to execute |
3087 | * @ew: guaranteed storage for the execute work structure (must |
3088 | * be available when the work executes) |
3089 | * |
3090 | * Executes the function immediately if process context is available, |
3091 | * otherwise schedules the function for delayed execution. |
3092 | * |
3093 | * Returns: 0 - function was executed |
3094 | * 1 - function was scheduled for execution |
3095 | */ |
3096 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
3097 | { |
3098 | if (!in_interrupt()) { |
3099 | fn(&ew->work); |
3100 | return 0; |
3101 | } |
3102 | |
3103 | INIT_WORK(&ew->work, fn); |
3104 | schedule_work(&ew->work); |
3105 | |
3106 | return 1; |
3107 | } |
3108 | EXPORT_SYMBOL_GPL(execute_in_process_context); |
3109 | |
3110 | int keventd_up(void) |
3111 | { |
3112 | return system_wq != NULL; |
3113 | } |
3114 | |
3115 | static int alloc_cwqs(struct workqueue_struct *wq) |
3116 | { |
3117 | /* |
3118 | * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. |
3119 | * Make sure that the alignment isn't lower than that of |
3120 | * unsigned long long. |
3121 | */ |
3122 | const size_t size = sizeof(struct cpu_workqueue_struct); |
3123 | const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, |
3124 | __alignof__(unsigned long long)); |
3125 | |
3126 | if (!(wq->flags & WQ_UNBOUND)) |
3127 | wq->cpu_wq.pcpu = __alloc_percpu(size, align); |
3128 | else { |
3129 | void *ptr; |
3130 | |
3131 | /* |
3132 | * Allocate enough room to align cwq and put an extra |
3133 | * pointer at the end pointing back to the originally |
3134 | * allocated pointer which will be used for free. |
3135 | */ |
3136 | ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); |
3137 | if (ptr) { |
3138 | wq->cpu_wq.single = PTR_ALIGN(ptr, align); |
3139 | *(void **)(wq->cpu_wq.single + 1) = ptr; |
3140 | } |
3141 | } |
3142 | |
3143 | /* just in case, make sure it's actually aligned */ |
3144 | BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); |
3145 | return wq->cpu_wq.v ? 0 : -ENOMEM; |
3146 | } |
3147 | |
3148 | static void free_cwqs(struct workqueue_struct *wq) |
3149 | { |
3150 | if (!(wq->flags & WQ_UNBOUND)) |
3151 | free_percpu(wq->cpu_wq.pcpu); |
3152 | else if (wq->cpu_wq.single) { |
3153 | /* the pointer to free is stored right after the cwq */ |
3154 | kfree(*(void **)(wq->cpu_wq.single + 1)); |
3155 | } |
3156 | } |
3157 | |
3158 | static int wq_clamp_max_active(int max_active, unsigned int flags, |
3159 | const char *name) |
3160 | { |
3161 | int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; |
3162 | |
3163 | if (max_active < 1 || max_active > lim) |
3164 | printk(KERN_WARNING "workqueue: max_active %d requested for %s " |
3165 | "is out of range, clamping between %d and %d\n", |
3166 | max_active, name, 1, lim); |
3167 | |
3168 | return clamp_val(max_active, 1, lim); |
3169 | } |
3170 | |
3171 | struct workqueue_struct *__alloc_workqueue_key(const char *fmt, |
3172 | unsigned int flags, |
3173 | int max_active, |
3174 | struct lock_class_key *key, |
3175 | const char *lock_name, ...) |
3176 | { |
3177 | va_list args, args1; |
3178 | struct workqueue_struct *wq; |
3179 | unsigned int cpu; |
3180 | size_t namelen; |
3181 | |
3182 | /* determine namelen, allocate wq and format name */ |
3183 | va_start(args, lock_name); |
3184 | va_copy(args1, args); |
3185 | namelen = vsnprintf(NULL, 0, fmt, args) + 1; |
3186 | |
3187 | wq = kzalloc(sizeof(*wq) + namelen, GFP_KERNEL); |
3188 | if (!wq) |
3189 | goto err; |
3190 | |
3191 | vsnprintf(wq->name, namelen, fmt, args1); |
3192 | va_end(args); |
3193 | va_end(args1); |
3194 | |
3195 | /* |
3196 | * Workqueues which may be used during memory reclaim should |
3197 | * have a rescuer to guarantee forward progress. |
3198 | */ |
3199 | if (flags & WQ_MEM_RECLAIM) |
3200 | flags |= WQ_RESCUER; |
3201 | |
3202 | max_active = max_active ?: WQ_DFL_ACTIVE; |
3203 | max_active = wq_clamp_max_active(max_active, flags, wq->name); |
3204 | |
3205 | /* init wq */ |
3206 | wq->flags = flags; |
3207 | wq->saved_max_active = max_active; |
3208 | mutex_init(&wq->flush_mutex); |
3209 | atomic_set(&wq->nr_cwqs_to_flush, 0); |
3210 | INIT_LIST_HEAD(&wq->flusher_queue); |
3211 | INIT_LIST_HEAD(&wq->flusher_overflow); |
3212 | |
3213 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
3214 | INIT_LIST_HEAD(&wq->list); |
3215 | |
3216 | if (alloc_cwqs(wq) < 0) |
3217 | goto err; |
3218 | |
3219 | for_each_cwq_cpu(cpu, wq) { |
3220 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3221 | struct global_cwq *gcwq = get_gcwq(cpu); |
3222 | int pool_idx = (bool)(flags & WQ_HIGHPRI); |
3223 | |
3224 | BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); |
3225 | cwq->pool = &gcwq->pools[pool_idx]; |
3226 | cwq->wq = wq; |
3227 | cwq->flush_color = -1; |
3228 | cwq->max_active = max_active; |
3229 | INIT_LIST_HEAD(&cwq->delayed_works); |
3230 | } |
3231 | |
3232 | if (flags & WQ_RESCUER) { |
3233 | struct worker *rescuer; |
3234 | |
3235 | if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) |
3236 | goto err; |
3237 | |
3238 | wq->rescuer = rescuer = alloc_worker(); |
3239 | if (!rescuer) |
3240 | goto err; |
3241 | |
3242 | rescuer->task = kthread_create(rescuer_thread, wq, "%s", |
3243 | wq->name); |
3244 | if (IS_ERR(rescuer->task)) |
3245 | goto err; |
3246 | |
3247 | rescuer->task->flags |= PF_THREAD_BOUND; |
3248 | wake_up_process(rescuer->task); |
3249 | } |
3250 | |
3251 | /* |
3252 | * workqueue_lock protects global freeze state and workqueues |
3253 | * list. Grab it, set max_active accordingly and add the new |
3254 | * workqueue to workqueues list. |
3255 | */ |
3256 | spin_lock(&workqueue_lock); |
3257 | |
3258 | if (workqueue_freezing && wq->flags & WQ_FREEZABLE) |
3259 | for_each_cwq_cpu(cpu, wq) |
3260 | get_cwq(cpu, wq)->max_active = 0; |
3261 | |
3262 | list_add(&wq->list, &workqueues); |
3263 | |
3264 | spin_unlock(&workqueue_lock); |
3265 | |
3266 | return wq; |
3267 | err: |
3268 | if (wq) { |
3269 | free_cwqs(wq); |
3270 | free_mayday_mask(wq->mayday_mask); |
3271 | kfree(wq->rescuer); |
3272 | kfree(wq); |
3273 | } |
3274 | return NULL; |
3275 | } |
3276 | EXPORT_SYMBOL_GPL(__alloc_workqueue_key); |
3277 | |
3278 | /** |
3279 | * destroy_workqueue - safely terminate a workqueue |
3280 | * @wq: target workqueue |
3281 | * |
3282 | * Safely destroy a workqueue. All work currently pending will be done first. |
3283 | */ |
3284 | void destroy_workqueue(struct workqueue_struct *wq) |
3285 | { |
3286 | unsigned int cpu; |
3287 | |
3288 | /* drain it before proceeding with destruction */ |
3289 | drain_workqueue(wq); |
3290 | |
3291 | /* |
3292 | * wq list is used to freeze wq, remove from list after |
3293 | * flushing is complete in case freeze races us. |
3294 | */ |
3295 | spin_lock(&workqueue_lock); |
3296 | list_del(&wq->list); |
3297 | spin_unlock(&workqueue_lock); |
3298 | |
3299 | /* sanity check */ |
3300 | for_each_cwq_cpu(cpu, wq) { |
3301 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3302 | int i; |
3303 | |
3304 | for (i = 0; i < WORK_NR_COLORS; i++) |
3305 | BUG_ON(cwq->nr_in_flight[i]); |
3306 | BUG_ON(cwq->nr_active); |
3307 | BUG_ON(!list_empty(&cwq->delayed_works)); |
3308 | } |
3309 | |
3310 | if (wq->flags & WQ_RESCUER) { |
3311 | kthread_stop(wq->rescuer->task); |
3312 | free_mayday_mask(wq->mayday_mask); |
3313 | kfree(wq->rescuer); |
3314 | } |
3315 | |
3316 | free_cwqs(wq); |
3317 | kfree(wq); |
3318 | } |
3319 | EXPORT_SYMBOL_GPL(destroy_workqueue); |
3320 | |
3321 | /** |
3322 | * workqueue_set_max_active - adjust max_active of a workqueue |
3323 | * @wq: target workqueue |
3324 | * @max_active: new max_active value. |
3325 | * |
3326 | * Set max_active of @wq to @max_active. |
3327 | * |
3328 | * CONTEXT: |
3329 | * Don't call from IRQ context. |
3330 | */ |
3331 | void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) |
3332 | { |
3333 | unsigned int cpu; |
3334 | |
3335 | max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); |
3336 | |
3337 | spin_lock(&workqueue_lock); |
3338 | |
3339 | wq->saved_max_active = max_active; |
3340 | |
3341 | for_each_cwq_cpu(cpu, wq) { |
3342 | struct global_cwq *gcwq = get_gcwq(cpu); |
3343 | |
3344 | spin_lock_irq(&gcwq->lock); |
3345 | |
3346 | if (!(wq->flags & WQ_FREEZABLE) || |
3347 | !(gcwq->flags & GCWQ_FREEZING)) |
3348 | get_cwq(gcwq->cpu, wq)->max_active = max_active; |
3349 | |
3350 | spin_unlock_irq(&gcwq->lock); |
3351 | } |
3352 | |
3353 | spin_unlock(&workqueue_lock); |
3354 | } |
3355 | EXPORT_SYMBOL_GPL(workqueue_set_max_active); |
3356 | |
3357 | /** |
3358 | * workqueue_congested - test whether a workqueue is congested |
3359 | * @cpu: CPU in question |
3360 | * @wq: target workqueue |
3361 | * |
3362 | * Test whether @wq's cpu workqueue for @cpu is congested. There is |
3363 | * no synchronization around this function and the test result is |
3364 | * unreliable and only useful as advisory hints or for debugging. |
3365 | * |
3366 | * RETURNS: |
3367 | * %true if congested, %false otherwise. |
3368 | */ |
3369 | bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) |
3370 | { |
3371 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3372 | |
3373 | return !list_empty(&cwq->delayed_works); |
3374 | } |
3375 | EXPORT_SYMBOL_GPL(workqueue_congested); |
3376 | |
3377 | /** |
3378 | * work_cpu - return the last known associated cpu for @work |
3379 | * @work: the work of interest |
3380 | * |
3381 | * RETURNS: |
3382 | * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. |
3383 | */ |
3384 | unsigned int work_cpu(struct work_struct *work) |
3385 | { |
3386 | struct global_cwq *gcwq = get_work_gcwq(work); |
3387 | |
3388 | return gcwq ? gcwq->cpu : WORK_CPU_NONE; |
3389 | } |
3390 | EXPORT_SYMBOL_GPL(work_cpu); |
3391 | |
3392 | /** |
3393 | * work_busy - test whether a work is currently pending or running |
3394 | * @work: the work to be tested |
3395 | * |
3396 | * Test whether @work is currently pending or running. There is no |
3397 | * synchronization around this function and the test result is |
3398 | * unreliable and only useful as advisory hints or for debugging. |
3399 | * Especially for reentrant wqs, the pending state might hide the |
3400 | * running state. |
3401 | * |
3402 | * RETURNS: |
3403 | * OR'd bitmask of WORK_BUSY_* bits. |
3404 | */ |
3405 | unsigned int work_busy(struct work_struct *work) |
3406 | { |
3407 | struct global_cwq *gcwq = get_work_gcwq(work); |
3408 | unsigned long flags; |
3409 | unsigned int ret = 0; |
3410 | |
3411 | if (!gcwq) |
3412 | return false; |
3413 | |
3414 | spin_lock_irqsave(&gcwq->lock, flags); |
3415 | |
3416 | if (work_pending(work)) |
3417 | ret |= WORK_BUSY_PENDING; |
3418 | if (find_worker_executing_work(gcwq, work)) |
3419 | ret |= WORK_BUSY_RUNNING; |
3420 | |
3421 | spin_unlock_irqrestore(&gcwq->lock, flags); |
3422 | |
3423 | return ret; |
3424 | } |
3425 | EXPORT_SYMBOL_GPL(work_busy); |
3426 | |
3427 | /* |
3428 | * CPU hotplug. |
3429 | * |
3430 | * There are two challenges in supporting CPU hotplug. Firstly, there |
3431 | * are a lot of assumptions on strong associations among work, cwq and |
3432 | * gcwq which make migrating pending and scheduled works very |
3433 | * difficult to implement without impacting hot paths. Secondly, |
3434 | * gcwqs serve mix of short, long and very long running works making |
3435 | * blocked draining impractical. |
3436 | * |
3437 | * This is solved by allowing a gcwq to be disassociated from the CPU |
3438 | * running as an unbound one and allowing it to be reattached later if the |
3439 | * cpu comes back online. |
3440 | */ |
3441 | |
3442 | /* claim manager positions of all pools */ |
3443 | static void gcwq_claim_management_and_lock(struct global_cwq *gcwq) |
3444 | { |
3445 | struct worker_pool *pool; |
3446 | |
3447 | for_each_worker_pool(pool, gcwq) |
3448 | mutex_lock_nested(&pool->manager_mutex, pool - gcwq->pools); |
3449 | spin_lock_irq(&gcwq->lock); |
3450 | } |
3451 | |
3452 | /* release manager positions */ |
3453 | static void gcwq_release_management_and_unlock(struct global_cwq *gcwq) |
3454 | { |
3455 | struct worker_pool *pool; |
3456 | |
3457 | spin_unlock_irq(&gcwq->lock); |
3458 | for_each_worker_pool(pool, gcwq) |
3459 | mutex_unlock(&pool->manager_mutex); |
3460 | } |
3461 | |
3462 | static void gcwq_unbind_fn(struct work_struct *work) |
3463 | { |
3464 | struct global_cwq *gcwq = get_gcwq(smp_processor_id()); |
3465 | struct worker_pool *pool; |
3466 | struct worker *worker; |
3467 | struct hlist_node *pos; |
3468 | int i; |
3469 | |
3470 | BUG_ON(gcwq->cpu != smp_processor_id()); |
3471 | |
3472 | gcwq_claim_management_and_lock(gcwq); |
3473 | |
3474 | /* |
3475 | * We've claimed all manager positions. Make all workers unbound |
3476 | * and set DISASSOCIATED. Before this, all workers except for the |
3477 | * ones which are still executing works from before the last CPU |
3478 | * down must be on the cpu. After this, they may become diasporas. |
3479 | */ |
3480 | for_each_worker_pool(pool, gcwq) |
3481 | list_for_each_entry(worker, &pool->idle_list, entry) |
3482 | worker->flags |= WORKER_UNBOUND; |
3483 | |
3484 | for_each_busy_worker(worker, i, pos, gcwq) |
3485 | worker->flags |= WORKER_UNBOUND; |
3486 | |
3487 | gcwq->flags |= GCWQ_DISASSOCIATED; |
3488 | |
3489 | gcwq_release_management_and_unlock(gcwq); |
3490 | |
3491 | /* |
3492 | * Call schedule() so that we cross rq->lock and thus can guarantee |
3493 | * sched callbacks see the %WORKER_UNBOUND flag. This is necessary |
3494 | * as scheduler callbacks may be invoked from other cpus. |
3495 | */ |
3496 | schedule(); |
3497 | |
3498 | /* |
3499 | * Sched callbacks are disabled now. Zap nr_running. After this, |
3500 | * nr_running stays zero and need_more_worker() and keep_working() |
3501 | * are always true as long as the worklist is not empty. @gcwq now |
3502 | * behaves as unbound (in terms of concurrency management) gcwq |
3503 | * which is served by workers tied to the CPU. |
3504 | * |
3505 | * On return from this function, the current worker would trigger |
3506 | * unbound chain execution of pending work items if other workers |
3507 | * didn't already. |
3508 | */ |
3509 | for_each_worker_pool(pool, gcwq) |
3510 | atomic_set(get_pool_nr_running(pool), 0); |
3511 | } |
3512 | |
3513 | /* |
3514 | * Workqueues should be brought up before normal priority CPU notifiers. |
3515 | * This will be registered high priority CPU notifier. |
3516 | */ |
3517 | static int __devinit workqueue_cpu_up_callback(struct notifier_block *nfb, |
3518 | unsigned long action, |
3519 | void *hcpu) |
3520 | { |
3521 | unsigned int cpu = (unsigned long)hcpu; |
3522 | struct global_cwq *gcwq = get_gcwq(cpu); |
3523 | struct worker_pool *pool; |
3524 | |
3525 | switch (action & ~CPU_TASKS_FROZEN) { |
3526 | case CPU_UP_PREPARE: |
3527 | for_each_worker_pool(pool, gcwq) { |
3528 | struct worker *worker; |
3529 | |
3530 | if (pool->nr_workers) |
3531 | continue; |
3532 | |
3533 | worker = create_worker(pool); |
3534 | if (!worker) |
3535 | return NOTIFY_BAD; |
3536 | |
3537 | spin_lock_irq(&gcwq->lock); |
3538 | start_worker(worker); |
3539 | spin_unlock_irq(&gcwq->lock); |
3540 | } |
3541 | break; |
3542 | |
3543 | case CPU_DOWN_FAILED: |
3544 | case CPU_ONLINE: |
3545 | gcwq_claim_management_and_lock(gcwq); |
3546 | gcwq->flags &= ~GCWQ_DISASSOCIATED; |
3547 | rebind_workers(gcwq); |
3548 | gcwq_release_management_and_unlock(gcwq); |
3549 | break; |
3550 | } |
3551 | return NOTIFY_OK; |
3552 | } |
3553 | |
3554 | /* |
3555 | * Workqueues should be brought down after normal priority CPU notifiers. |
3556 | * This will be registered as low priority CPU notifier. |
3557 | */ |
3558 | static int __devinit workqueue_cpu_down_callback(struct notifier_block *nfb, |
3559 | unsigned long action, |
3560 | void *hcpu) |
3561 | { |
3562 | unsigned int cpu = (unsigned long)hcpu; |
3563 | struct work_struct unbind_work; |
3564 | |
3565 | switch (action & ~CPU_TASKS_FROZEN) { |
3566 | case CPU_DOWN_PREPARE: |
3567 | /* unbinding should happen on the local CPU */ |
3568 | INIT_WORK_ONSTACK(&unbind_work, gcwq_unbind_fn); |
3569 | schedule_work_on(cpu, &unbind_work); |
3570 | flush_work(&unbind_work); |
3571 | break; |
3572 | } |
3573 | return NOTIFY_OK; |
3574 | } |
3575 | |
3576 | #ifdef CONFIG_SMP |
3577 | |
3578 | struct work_for_cpu { |
3579 | struct work_struct work; |
3580 | long (*fn)(void *); |
3581 | void *arg; |
3582 | long ret; |
3583 | }; |
3584 | |
3585 | static void work_for_cpu_fn(struct work_struct *work) |
3586 | { |
3587 | struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); |
3588 | |
3589 | wfc->ret = wfc->fn(wfc->arg); |
3590 | } |
3591 | |
3592 | /** |
3593 | * work_on_cpu - run a function in user context on a particular cpu |
3594 | * @cpu: the cpu to run on |
3595 | * @fn: the function to run |
3596 | * @arg: the function arg |
3597 | * |
3598 | * This will return the value @fn returns. |
3599 | * It is up to the caller to ensure that the cpu doesn't go offline. |
3600 | * The caller must not hold any locks which would prevent @fn from completing. |
3601 | */ |
3602 | long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) |
3603 | { |
3604 | struct work_for_cpu wfc = { .fn = fn, .arg = arg }; |
3605 | |
3606 | INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); |
3607 | schedule_work_on(cpu, &wfc.work); |
3608 | flush_work(&wfc.work); |
3609 | return wfc.ret; |
3610 | } |
3611 | EXPORT_SYMBOL_GPL(work_on_cpu); |
3612 | #endif /* CONFIG_SMP */ |
3613 | |
3614 | #ifdef CONFIG_FREEZER |
3615 | |
3616 | /** |
3617 | * freeze_workqueues_begin - begin freezing workqueues |
3618 | * |
3619 | * Start freezing workqueues. After this function returns, all freezable |
3620 | * workqueues will queue new works to their frozen_works list instead of |
3621 | * gcwq->worklist. |
3622 | * |
3623 | * CONTEXT: |
3624 | * Grabs and releases workqueue_lock and gcwq->lock's. |
3625 | */ |
3626 | void freeze_workqueues_begin(void) |
3627 | { |
3628 | unsigned int cpu; |
3629 | |
3630 | spin_lock(&workqueue_lock); |
3631 | |
3632 | BUG_ON(workqueue_freezing); |
3633 | workqueue_freezing = true; |
3634 | |
3635 | for_each_gcwq_cpu(cpu) { |
3636 | struct global_cwq *gcwq = get_gcwq(cpu); |
3637 | struct workqueue_struct *wq; |
3638 | |
3639 | spin_lock_irq(&gcwq->lock); |
3640 | |
3641 | BUG_ON(gcwq->flags & GCWQ_FREEZING); |
3642 | gcwq->flags |= GCWQ_FREEZING; |
3643 | |
3644 | list_for_each_entry(wq, &workqueues, list) { |
3645 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3646 | |
3647 | if (cwq && wq->flags & WQ_FREEZABLE) |
3648 | cwq->max_active = 0; |
3649 | } |
3650 | |
3651 | spin_unlock_irq(&gcwq->lock); |
3652 | } |
3653 | |
3654 | spin_unlock(&workqueue_lock); |
3655 | } |
3656 | |
3657 | /** |
3658 | * freeze_workqueues_busy - are freezable workqueues still busy? |
3659 | * |
3660 | * Check whether freezing is complete. This function must be called |
3661 | * between freeze_workqueues_begin() and thaw_workqueues(). |
3662 | * |
3663 | * CONTEXT: |
3664 | * Grabs and releases workqueue_lock. |
3665 | * |
3666 | * RETURNS: |
3667 | * %true if some freezable workqueues are still busy. %false if freezing |
3668 | * is complete. |
3669 | */ |
3670 | bool freeze_workqueues_busy(void) |
3671 | { |
3672 | unsigned int cpu; |
3673 | bool busy = false; |
3674 | |
3675 | spin_lock(&workqueue_lock); |
3676 | |
3677 | BUG_ON(!workqueue_freezing); |
3678 | |
3679 | for_each_gcwq_cpu(cpu) { |
3680 | struct workqueue_struct *wq; |
3681 | /* |
3682 | * nr_active is monotonically decreasing. It's safe |
3683 | * to peek without lock. |
3684 | */ |
3685 | list_for_each_entry(wq, &workqueues, list) { |
3686 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3687 | |
3688 | if (!cwq || !(wq->flags & WQ_FREEZABLE)) |
3689 | continue; |
3690 | |
3691 | BUG_ON(cwq->nr_active < 0); |
3692 | if (cwq->nr_active) { |
3693 | busy = true; |
3694 | goto out_unlock; |
3695 | } |
3696 | } |
3697 | } |
3698 | out_unlock: |
3699 | spin_unlock(&workqueue_lock); |
3700 | return busy; |
3701 | } |
3702 | |
3703 | /** |
3704 | * thaw_workqueues - thaw workqueues |
3705 | * |
3706 | * Thaw workqueues. Normal queueing is restored and all collected |
3707 | * frozen works are transferred to their respective gcwq worklists. |
3708 | * |
3709 | * CONTEXT: |
3710 | * Grabs and releases workqueue_lock and gcwq->lock's. |
3711 | */ |
3712 | void thaw_workqueues(void) |
3713 | { |
3714 | unsigned int cpu; |
3715 | |
3716 | spin_lock(&workqueue_lock); |
3717 | |
3718 | if (!workqueue_freezing) |
3719 | goto out_unlock; |
3720 | |
3721 | for_each_gcwq_cpu(cpu) { |
3722 | struct global_cwq *gcwq = get_gcwq(cpu); |
3723 | struct worker_pool *pool; |
3724 | struct workqueue_struct *wq; |
3725 | |
3726 | spin_lock_irq(&gcwq->lock); |
3727 | |
3728 | BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); |
3729 | gcwq->flags &= ~GCWQ_FREEZING; |
3730 | |
3731 | list_for_each_entry(wq, &workqueues, list) { |
3732 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3733 | |
3734 | if (!cwq || !(wq->flags & WQ_FREEZABLE)) |
3735 | continue; |
3736 | |
3737 | /* restore max_active and repopulate worklist */ |
3738 | cwq->max_active = wq->saved_max_active; |
3739 | |
3740 | while (!list_empty(&cwq->delayed_works) && |
3741 | cwq->nr_active < cwq->max_active) |
3742 | cwq_activate_first_delayed(cwq); |
3743 | } |
3744 | |
3745 | for_each_worker_pool(pool, gcwq) |
3746 | wake_up_worker(pool); |
3747 | |
3748 | spin_unlock_irq(&gcwq->lock); |
3749 | } |
3750 | |
3751 | workqueue_freezing = false; |
3752 | out_unlock: |
3753 | spin_unlock(&workqueue_lock); |
3754 | } |
3755 | #endif /* CONFIG_FREEZER */ |
3756 | |
3757 | static int __init init_workqueues(void) |
3758 | { |
3759 | unsigned int cpu; |
3760 | int i; |
3761 | |
3762 | cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); |
3763 | cpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); |
3764 | |
3765 | /* initialize gcwqs */ |
3766 | for_each_gcwq_cpu(cpu) { |
3767 | struct global_cwq *gcwq = get_gcwq(cpu); |
3768 | struct worker_pool *pool; |
3769 | |
3770 | spin_lock_init(&gcwq->lock); |
3771 | gcwq->cpu = cpu; |
3772 | gcwq->flags |= GCWQ_DISASSOCIATED; |
3773 | |
3774 | for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) |
3775 | INIT_HLIST_HEAD(&gcwq->busy_hash[i]); |
3776 | |
3777 | for_each_worker_pool(pool, gcwq) { |
3778 | pool->gcwq = gcwq; |
3779 | INIT_LIST_HEAD(&pool->worklist); |
3780 | INIT_LIST_HEAD(&pool->idle_list); |
3781 | |
3782 | init_timer_deferrable(&pool->idle_timer); |
3783 | pool->idle_timer.function = idle_worker_timeout; |
3784 | pool->idle_timer.data = (unsigned long)pool; |
3785 | |
3786 | setup_timer(&pool->mayday_timer, gcwq_mayday_timeout, |
3787 | (unsigned long)pool); |
3788 | |
3789 | mutex_init(&pool->manager_mutex); |
3790 | ida_init(&pool->worker_ida); |
3791 | } |
3792 | |
3793 | init_waitqueue_head(&gcwq->rebind_hold); |
3794 | } |
3795 | |
3796 | /* create the initial worker */ |
3797 | for_each_online_gcwq_cpu(cpu) { |
3798 | struct global_cwq *gcwq = get_gcwq(cpu); |
3799 | struct worker_pool *pool; |
3800 | |
3801 | if (cpu != WORK_CPU_UNBOUND) |
3802 | gcwq->flags &= ~GCWQ_DISASSOCIATED; |
3803 | |
3804 | for_each_worker_pool(pool, gcwq) { |
3805 | struct worker *worker; |
3806 | |
3807 | worker = create_worker(pool); |
3808 | BUG_ON(!worker); |
3809 | spin_lock_irq(&gcwq->lock); |
3810 | start_worker(worker); |
3811 | spin_unlock_irq(&gcwq->lock); |
3812 | } |
3813 | } |
3814 | |
3815 | system_wq = alloc_workqueue("events", 0, 0); |
3816 | system_long_wq = alloc_workqueue("events_long", 0, 0); |
3817 | system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); |
3818 | system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, |
3819 | WQ_UNBOUND_MAX_ACTIVE); |
3820 | system_freezable_wq = alloc_workqueue("events_freezable", |
3821 | WQ_FREEZABLE, 0); |
3822 | system_nrt_freezable_wq = alloc_workqueue("events_nrt_freezable", |
3823 | WQ_NON_REENTRANT | WQ_FREEZABLE, 0); |
3824 | BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq || |
3825 | !system_unbound_wq || !system_freezable_wq || |
3826 | !system_nrt_freezable_wq); |
3827 | return 0; |
3828 | } |
3829 | early_initcall(init_workqueues); |
3830 |
Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master
Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9