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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/module.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 | #define CREATE_TRACE_POINTS |
46 | #include <trace/events/workqueue.h> |
47 | |
48 | #include "workqueue_sched.h" |
49 | |
50 | enum { |
51 | /* global_cwq flags */ |
52 | GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ |
53 | GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */ |
54 | GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ |
55 | GCWQ_FREEZING = 1 << 3, /* freeze in progress */ |
56 | GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */ |
57 | |
58 | /* worker flags */ |
59 | WORKER_STARTED = 1 << 0, /* started */ |
60 | WORKER_DIE = 1 << 1, /* die die die */ |
61 | WORKER_IDLE = 1 << 2, /* is idle */ |
62 | WORKER_PREP = 1 << 3, /* preparing to run works */ |
63 | WORKER_ROGUE = 1 << 4, /* not bound to any cpu */ |
64 | WORKER_REBIND = 1 << 5, /* mom is home, come back */ |
65 | WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ |
66 | WORKER_UNBOUND = 1 << 7, /* worker is unbound */ |
67 | |
68 | WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND | |
69 | WORKER_CPU_INTENSIVE | WORKER_UNBOUND, |
70 | |
71 | /* gcwq->trustee_state */ |
72 | TRUSTEE_START = 0, /* start */ |
73 | TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */ |
74 | TRUSTEE_BUTCHER = 2, /* butcher workers */ |
75 | TRUSTEE_RELEASE = 3, /* release workers */ |
76 | TRUSTEE_DONE = 4, /* trustee is done */ |
77 | |
78 | BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ |
79 | BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, |
80 | BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, |
81 | |
82 | MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ |
83 | IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ |
84 | |
85 | MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */ |
86 | MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ |
87 | CREATE_COOLDOWN = HZ, /* time to breath after fail */ |
88 | TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */ |
89 | |
90 | /* |
91 | * Rescue workers are used only on emergencies and shared by |
92 | * all cpus. Give -20. |
93 | */ |
94 | RESCUER_NICE_LEVEL = -20, |
95 | }; |
96 | |
97 | /* |
98 | * Structure fields follow one of the following exclusion rules. |
99 | * |
100 | * I: Modifiable by initialization/destruction paths and read-only for |
101 | * everyone else. |
102 | * |
103 | * P: Preemption protected. Disabling preemption is enough and should |
104 | * only be modified and accessed from the local cpu. |
105 | * |
106 | * L: gcwq->lock protected. Access with gcwq->lock held. |
107 | * |
108 | * X: During normal operation, modification requires gcwq->lock and |
109 | * should be done only from local cpu. Either disabling preemption |
110 | * on local cpu or grabbing gcwq->lock is enough for read access. |
111 | * If GCWQ_DISASSOCIATED is set, it's identical to L. |
112 | * |
113 | * F: wq->flush_mutex protected. |
114 | * |
115 | * W: workqueue_lock protected. |
116 | */ |
117 | |
118 | struct global_cwq; |
119 | |
120 | /* |
121 | * The poor guys doing the actual heavy lifting. All on-duty workers |
122 | * are either serving the manager role, on idle list or on busy hash. |
123 | */ |
124 | struct worker { |
125 | /* on idle list while idle, on busy hash table while busy */ |
126 | union { |
127 | struct list_head entry; /* L: while idle */ |
128 | struct hlist_node hentry; /* L: while busy */ |
129 | }; |
130 | |
131 | struct work_struct *current_work; /* L: work being processed */ |
132 | struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ |
133 | struct list_head scheduled; /* L: scheduled works */ |
134 | struct task_struct *task; /* I: worker task */ |
135 | struct global_cwq *gcwq; /* I: the associated gcwq */ |
136 | /* 64 bytes boundary on 64bit, 32 on 32bit */ |
137 | unsigned long last_active; /* L: last active timestamp */ |
138 | unsigned int flags; /* X: flags */ |
139 | int id; /* I: worker id */ |
140 | struct work_struct rebind_work; /* L: rebind worker to cpu */ |
141 | }; |
142 | |
143 | /* |
144 | * Global per-cpu workqueue. There's one and only one for each cpu |
145 | * and all works are queued and processed here regardless of their |
146 | * target workqueues. |
147 | */ |
148 | struct global_cwq { |
149 | spinlock_t lock; /* the gcwq lock */ |
150 | struct list_head worklist; /* L: list of pending works */ |
151 | unsigned int cpu; /* I: the associated cpu */ |
152 | unsigned int flags; /* L: GCWQ_* flags */ |
153 | |
154 | int nr_workers; /* L: total number of workers */ |
155 | int nr_idle; /* L: currently idle ones */ |
156 | |
157 | /* workers are chained either in the idle_list or busy_hash */ |
158 | struct list_head idle_list; /* X: list of idle workers */ |
159 | struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; |
160 | /* L: hash of busy workers */ |
161 | |
162 | struct timer_list idle_timer; /* L: worker idle timeout */ |
163 | struct timer_list mayday_timer; /* L: SOS timer for dworkers */ |
164 | |
165 | struct ida worker_ida; /* L: for worker IDs */ |
166 | |
167 | struct task_struct *trustee; /* L: for gcwq shutdown */ |
168 | unsigned int trustee_state; /* L: trustee state */ |
169 | wait_queue_head_t trustee_wait; /* trustee wait */ |
170 | struct worker *first_idle; /* L: first idle worker */ |
171 | } ____cacheline_aligned_in_smp; |
172 | |
173 | /* |
174 | * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of |
175 | * work_struct->data are used for flags and thus cwqs need to be |
176 | * aligned at two's power of the number of flag bits. |
177 | */ |
178 | struct cpu_workqueue_struct { |
179 | struct global_cwq *gcwq; /* I: the associated gcwq */ |
180 | struct workqueue_struct *wq; /* I: the owning workqueue */ |
181 | int work_color; /* L: current color */ |
182 | int flush_color; /* L: flushing color */ |
183 | int nr_in_flight[WORK_NR_COLORS]; |
184 | /* L: nr of in_flight works */ |
185 | int nr_active; /* L: nr of active works */ |
186 | int max_active; /* L: max active works */ |
187 | struct list_head delayed_works; /* L: delayed works */ |
188 | }; |
189 | |
190 | /* |
191 | * Structure used to wait for workqueue flush. |
192 | */ |
193 | struct wq_flusher { |
194 | struct list_head list; /* F: list of flushers */ |
195 | int flush_color; /* F: flush color waiting for */ |
196 | struct completion done; /* flush completion */ |
197 | }; |
198 | |
199 | /* |
200 | * All cpumasks are assumed to be always set on UP and thus can't be |
201 | * used to determine whether there's something to be done. |
202 | */ |
203 | #ifdef CONFIG_SMP |
204 | typedef cpumask_var_t mayday_mask_t; |
205 | #define mayday_test_and_set_cpu(cpu, mask) \ |
206 | cpumask_test_and_set_cpu((cpu), (mask)) |
207 | #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) |
208 | #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) |
209 | #define alloc_mayday_mask(maskp, gfp) zalloc_cpumask_var((maskp), (gfp)) |
210 | #define free_mayday_mask(mask) free_cpumask_var((mask)) |
211 | #else |
212 | typedef unsigned long mayday_mask_t; |
213 | #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) |
214 | #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) |
215 | #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) |
216 | #define alloc_mayday_mask(maskp, gfp) true |
217 | #define free_mayday_mask(mask) do { } while (0) |
218 | #endif |
219 | |
220 | /* |
221 | * The externally visible workqueue abstraction is an array of |
222 | * per-CPU workqueues: |
223 | */ |
224 | struct workqueue_struct { |
225 | unsigned int flags; /* I: WQ_* flags */ |
226 | union { |
227 | struct cpu_workqueue_struct __percpu *pcpu; |
228 | struct cpu_workqueue_struct *single; |
229 | unsigned long v; |
230 | } cpu_wq; /* I: cwq's */ |
231 | struct list_head list; /* W: list of all workqueues */ |
232 | |
233 | struct mutex flush_mutex; /* protects wq flushing */ |
234 | int work_color; /* F: current work color */ |
235 | int flush_color; /* F: current flush color */ |
236 | atomic_t nr_cwqs_to_flush; /* flush in progress */ |
237 | struct wq_flusher *first_flusher; /* F: first flusher */ |
238 | struct list_head flusher_queue; /* F: flush waiters */ |
239 | struct list_head flusher_overflow; /* F: flush overflow list */ |
240 | |
241 | mayday_mask_t mayday_mask; /* cpus requesting rescue */ |
242 | struct worker *rescuer; /* I: rescue worker */ |
243 | |
244 | int saved_max_active; /* W: saved cwq max_active */ |
245 | const char *name; /* I: workqueue name */ |
246 | #ifdef CONFIG_LOCKDEP |
247 | struct lockdep_map lockdep_map; |
248 | #endif |
249 | }; |
250 | |
251 | struct workqueue_struct *system_wq __read_mostly; |
252 | struct workqueue_struct *system_long_wq __read_mostly; |
253 | struct workqueue_struct *system_nrt_wq __read_mostly; |
254 | struct workqueue_struct *system_unbound_wq __read_mostly; |
255 | EXPORT_SYMBOL_GPL(system_wq); |
256 | EXPORT_SYMBOL_GPL(system_long_wq); |
257 | EXPORT_SYMBOL_GPL(system_nrt_wq); |
258 | EXPORT_SYMBOL_GPL(system_unbound_wq); |
259 | |
260 | #define for_each_busy_worker(worker, i, pos, gcwq) \ |
261 | for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ |
262 | hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) |
263 | |
264 | static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask, |
265 | unsigned int sw) |
266 | { |
267 | if (cpu < nr_cpu_ids) { |
268 | if (sw & 1) { |
269 | cpu = cpumask_next(cpu, mask); |
270 | if (cpu < nr_cpu_ids) |
271 | return cpu; |
272 | } |
273 | if (sw & 2) |
274 | return WORK_CPU_UNBOUND; |
275 | } |
276 | return WORK_CPU_NONE; |
277 | } |
278 | |
279 | static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, |
280 | struct workqueue_struct *wq) |
281 | { |
282 | return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); |
283 | } |
284 | |
285 | /* |
286 | * CPU iterators |
287 | * |
288 | * An extra gcwq is defined for an invalid cpu number |
289 | * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any |
290 | * specific CPU. The following iterators are similar to |
291 | * for_each_*_cpu() iterators but also considers the unbound gcwq. |
292 | * |
293 | * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND |
294 | * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND |
295 | * for_each_cwq_cpu() : possible CPUs for bound workqueues, |
296 | * WORK_CPU_UNBOUND for unbound workqueues |
297 | */ |
298 | #define for_each_gcwq_cpu(cpu) \ |
299 | for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \ |
300 | (cpu) < WORK_CPU_NONE; \ |
301 | (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3)) |
302 | |
303 | #define for_each_online_gcwq_cpu(cpu) \ |
304 | for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \ |
305 | (cpu) < WORK_CPU_NONE; \ |
306 | (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3)) |
307 | |
308 | #define for_each_cwq_cpu(cpu, wq) \ |
309 | for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \ |
310 | (cpu) < WORK_CPU_NONE; \ |
311 | (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq))) |
312 | |
313 | #ifdef CONFIG_LOCKDEP |
314 | /** |
315 | * in_workqueue_context() - in context of specified workqueue? |
316 | * @wq: the workqueue of interest |
317 | * |
318 | * Checks lockdep state to see if the current task is executing from |
319 | * within a workqueue item. This function exists only if lockdep is |
320 | * enabled. |
321 | */ |
322 | int in_workqueue_context(struct workqueue_struct *wq) |
323 | { |
324 | return lock_is_held(&wq->lockdep_map); |
325 | } |
326 | #endif |
327 | |
328 | #ifdef CONFIG_DEBUG_OBJECTS_WORK |
329 | |
330 | static struct debug_obj_descr work_debug_descr; |
331 | |
332 | /* |
333 | * fixup_init is called when: |
334 | * - an active object is initialized |
335 | */ |
336 | static int work_fixup_init(void *addr, enum debug_obj_state state) |
337 | { |
338 | struct work_struct *work = addr; |
339 | |
340 | switch (state) { |
341 | case ODEBUG_STATE_ACTIVE: |
342 | cancel_work_sync(work); |
343 | debug_object_init(work, &work_debug_descr); |
344 | return 1; |
345 | default: |
346 | return 0; |
347 | } |
348 | } |
349 | |
350 | /* |
351 | * fixup_activate is called when: |
352 | * - an active object is activated |
353 | * - an unknown object is activated (might be a statically initialized object) |
354 | */ |
355 | static int work_fixup_activate(void *addr, enum debug_obj_state state) |
356 | { |
357 | struct work_struct *work = addr; |
358 | |
359 | switch (state) { |
360 | |
361 | case ODEBUG_STATE_NOTAVAILABLE: |
362 | /* |
363 | * This is not really a fixup. The work struct was |
364 | * statically initialized. We just make sure that it |
365 | * is tracked in the object tracker. |
366 | */ |
367 | if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
368 | debug_object_init(work, &work_debug_descr); |
369 | debug_object_activate(work, &work_debug_descr); |
370 | return 0; |
371 | } |
372 | WARN_ON_ONCE(1); |
373 | return 0; |
374 | |
375 | case ODEBUG_STATE_ACTIVE: |
376 | WARN_ON(1); |
377 | |
378 | default: |
379 | return 0; |
380 | } |
381 | } |
382 | |
383 | /* |
384 | * fixup_free is called when: |
385 | * - an active object is freed |
386 | */ |
387 | static int work_fixup_free(void *addr, enum debug_obj_state state) |
388 | { |
389 | struct work_struct *work = addr; |
390 | |
391 | switch (state) { |
392 | case ODEBUG_STATE_ACTIVE: |
393 | cancel_work_sync(work); |
394 | debug_object_free(work, &work_debug_descr); |
395 | return 1; |
396 | default: |
397 | return 0; |
398 | } |
399 | } |
400 | |
401 | static struct debug_obj_descr work_debug_descr = { |
402 | .name = "work_struct", |
403 | .fixup_init = work_fixup_init, |
404 | .fixup_activate = work_fixup_activate, |
405 | .fixup_free = work_fixup_free, |
406 | }; |
407 | |
408 | static inline void debug_work_activate(struct work_struct *work) |
409 | { |
410 | debug_object_activate(work, &work_debug_descr); |
411 | } |
412 | |
413 | static inline void debug_work_deactivate(struct work_struct *work) |
414 | { |
415 | debug_object_deactivate(work, &work_debug_descr); |
416 | } |
417 | |
418 | void __init_work(struct work_struct *work, int onstack) |
419 | { |
420 | if (onstack) |
421 | debug_object_init_on_stack(work, &work_debug_descr); |
422 | else |
423 | debug_object_init(work, &work_debug_descr); |
424 | } |
425 | EXPORT_SYMBOL_GPL(__init_work); |
426 | |
427 | void destroy_work_on_stack(struct work_struct *work) |
428 | { |
429 | debug_object_free(work, &work_debug_descr); |
430 | } |
431 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); |
432 | |
433 | #else |
434 | static inline void debug_work_activate(struct work_struct *work) { } |
435 | static inline void debug_work_deactivate(struct work_struct *work) { } |
436 | #endif |
437 | |
438 | /* Serializes the accesses to the list of workqueues. */ |
439 | static DEFINE_SPINLOCK(workqueue_lock); |
440 | static LIST_HEAD(workqueues); |
441 | static bool workqueue_freezing; /* W: have wqs started freezing? */ |
442 | |
443 | /* |
444 | * The almighty global cpu workqueues. nr_running is the only field |
445 | * which is expected to be used frequently by other cpus via |
446 | * try_to_wake_up(). Put it in a separate cacheline. |
447 | */ |
448 | static DEFINE_PER_CPU(struct global_cwq, global_cwq); |
449 | static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running); |
450 | |
451 | /* |
452 | * Global cpu workqueue and nr_running counter for unbound gcwq. The |
453 | * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its |
454 | * workers have WORKER_UNBOUND set. |
455 | */ |
456 | static struct global_cwq unbound_global_cwq; |
457 | static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */ |
458 | |
459 | static int worker_thread(void *__worker); |
460 | |
461 | static struct global_cwq *get_gcwq(unsigned int cpu) |
462 | { |
463 | if (cpu != WORK_CPU_UNBOUND) |
464 | return &per_cpu(global_cwq, cpu); |
465 | else |
466 | return &unbound_global_cwq; |
467 | } |
468 | |
469 | static atomic_t *get_gcwq_nr_running(unsigned int cpu) |
470 | { |
471 | if (cpu != WORK_CPU_UNBOUND) |
472 | return &per_cpu(gcwq_nr_running, cpu); |
473 | else |
474 | return &unbound_gcwq_nr_running; |
475 | } |
476 | |
477 | static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, |
478 | struct workqueue_struct *wq) |
479 | { |
480 | if (!(wq->flags & WQ_UNBOUND)) { |
481 | if (likely(cpu < nr_cpu_ids)) { |
482 | #ifdef CONFIG_SMP |
483 | return per_cpu_ptr(wq->cpu_wq.pcpu, cpu); |
484 | #else |
485 | return wq->cpu_wq.single; |
486 | #endif |
487 | } |
488 | } else if (likely(cpu == WORK_CPU_UNBOUND)) |
489 | return wq->cpu_wq.single; |
490 | return NULL; |
491 | } |
492 | |
493 | static unsigned int work_color_to_flags(int color) |
494 | { |
495 | return color << WORK_STRUCT_COLOR_SHIFT; |
496 | } |
497 | |
498 | static int get_work_color(struct work_struct *work) |
499 | { |
500 | return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & |
501 | ((1 << WORK_STRUCT_COLOR_BITS) - 1); |
502 | } |
503 | |
504 | static int work_next_color(int color) |
505 | { |
506 | return (color + 1) % WORK_NR_COLORS; |
507 | } |
508 | |
509 | /* |
510 | * A work's data points to the cwq with WORK_STRUCT_CWQ set while the |
511 | * work is on queue. Once execution starts, WORK_STRUCT_CWQ is |
512 | * cleared and the work data contains the cpu number it was last on. |
513 | * |
514 | * set_work_{cwq|cpu}() and clear_work_data() can be used to set the |
515 | * cwq, cpu or clear work->data. These functions should only be |
516 | * called while the work is owned - ie. while the PENDING bit is set. |
517 | * |
518 | * get_work_[g]cwq() can be used to obtain the gcwq or cwq |
519 | * corresponding to a work. gcwq is available once the work has been |
520 | * queued anywhere after initialization. cwq is available only from |
521 | * queueing until execution starts. |
522 | */ |
523 | static inline void set_work_data(struct work_struct *work, unsigned long data, |
524 | unsigned long flags) |
525 | { |
526 | BUG_ON(!work_pending(work)); |
527 | atomic_long_set(&work->data, data | flags | work_static(work)); |
528 | } |
529 | |
530 | static void set_work_cwq(struct work_struct *work, |
531 | struct cpu_workqueue_struct *cwq, |
532 | unsigned long extra_flags) |
533 | { |
534 | set_work_data(work, (unsigned long)cwq, |
535 | WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); |
536 | } |
537 | |
538 | static void set_work_cpu(struct work_struct *work, unsigned int cpu) |
539 | { |
540 | set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); |
541 | } |
542 | |
543 | static void clear_work_data(struct work_struct *work) |
544 | { |
545 | set_work_data(work, WORK_STRUCT_NO_CPU, 0); |
546 | } |
547 | |
548 | static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) |
549 | { |
550 | unsigned long data = atomic_long_read(&work->data); |
551 | |
552 | if (data & WORK_STRUCT_CWQ) |
553 | return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); |
554 | else |
555 | return NULL; |
556 | } |
557 | |
558 | static struct global_cwq *get_work_gcwq(struct work_struct *work) |
559 | { |
560 | unsigned long data = atomic_long_read(&work->data); |
561 | unsigned int cpu; |
562 | |
563 | if (data & WORK_STRUCT_CWQ) |
564 | return ((struct cpu_workqueue_struct *) |
565 | (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq; |
566 | |
567 | cpu = data >> WORK_STRUCT_FLAG_BITS; |
568 | if (cpu == WORK_CPU_NONE) |
569 | return NULL; |
570 | |
571 | BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); |
572 | return get_gcwq(cpu); |
573 | } |
574 | |
575 | /* |
576 | * Policy functions. These define the policies on how the global |
577 | * worker pool is managed. Unless noted otherwise, these functions |
578 | * assume that they're being called with gcwq->lock held. |
579 | */ |
580 | |
581 | static bool __need_more_worker(struct global_cwq *gcwq) |
582 | { |
583 | return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) || |
584 | gcwq->flags & GCWQ_HIGHPRI_PENDING; |
585 | } |
586 | |
587 | /* |
588 | * Need to wake up a worker? Called from anything but currently |
589 | * running workers. |
590 | */ |
591 | static bool need_more_worker(struct global_cwq *gcwq) |
592 | { |
593 | return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq); |
594 | } |
595 | |
596 | /* Can I start working? Called from busy but !running workers. */ |
597 | static bool may_start_working(struct global_cwq *gcwq) |
598 | { |
599 | return gcwq->nr_idle; |
600 | } |
601 | |
602 | /* Do I need to keep working? Called from currently running workers. */ |
603 | static bool keep_working(struct global_cwq *gcwq) |
604 | { |
605 | atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); |
606 | |
607 | return !list_empty(&gcwq->worklist) && atomic_read(nr_running) <= 1; |
608 | } |
609 | |
610 | /* Do we need a new worker? Called from manager. */ |
611 | static bool need_to_create_worker(struct global_cwq *gcwq) |
612 | { |
613 | return need_more_worker(gcwq) && !may_start_working(gcwq); |
614 | } |
615 | |
616 | /* Do I need to be the manager? */ |
617 | static bool need_to_manage_workers(struct global_cwq *gcwq) |
618 | { |
619 | return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS; |
620 | } |
621 | |
622 | /* Do we have too many workers and should some go away? */ |
623 | static bool too_many_workers(struct global_cwq *gcwq) |
624 | { |
625 | bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS; |
626 | int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */ |
627 | int nr_busy = gcwq->nr_workers - nr_idle; |
628 | |
629 | return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; |
630 | } |
631 | |
632 | /* |
633 | * Wake up functions. |
634 | */ |
635 | |
636 | /* Return the first worker. Safe with preemption disabled */ |
637 | static struct worker *first_worker(struct global_cwq *gcwq) |
638 | { |
639 | if (unlikely(list_empty(&gcwq->idle_list))) |
640 | return NULL; |
641 | |
642 | return list_first_entry(&gcwq->idle_list, struct worker, entry); |
643 | } |
644 | |
645 | /** |
646 | * wake_up_worker - wake up an idle worker |
647 | * @gcwq: gcwq to wake worker for |
648 | * |
649 | * Wake up the first idle worker of @gcwq. |
650 | * |
651 | * CONTEXT: |
652 | * spin_lock_irq(gcwq->lock). |
653 | */ |
654 | static void wake_up_worker(struct global_cwq *gcwq) |
655 | { |
656 | struct worker *worker = first_worker(gcwq); |
657 | |
658 | if (likely(worker)) |
659 | wake_up_process(worker->task); |
660 | } |
661 | |
662 | /** |
663 | * wq_worker_waking_up - a worker is waking up |
664 | * @task: task waking up |
665 | * @cpu: CPU @task is waking up to |
666 | * |
667 | * This function is called during try_to_wake_up() when a worker is |
668 | * being awoken. |
669 | * |
670 | * CONTEXT: |
671 | * spin_lock_irq(rq->lock) |
672 | */ |
673 | void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) |
674 | { |
675 | struct worker *worker = kthread_data(task); |
676 | |
677 | if (likely(!(worker->flags & WORKER_NOT_RUNNING))) |
678 | atomic_inc(get_gcwq_nr_running(cpu)); |
679 | } |
680 | |
681 | /** |
682 | * wq_worker_sleeping - a worker is going to sleep |
683 | * @task: task going to sleep |
684 | * @cpu: CPU in question, must be the current CPU number |
685 | * |
686 | * This function is called during schedule() when a busy worker is |
687 | * going to sleep. Worker on the same cpu can be woken up by |
688 | * returning pointer to its task. |
689 | * |
690 | * CONTEXT: |
691 | * spin_lock_irq(rq->lock) |
692 | * |
693 | * RETURNS: |
694 | * Worker task on @cpu to wake up, %NULL if none. |
695 | */ |
696 | struct task_struct *wq_worker_sleeping(struct task_struct *task, |
697 | unsigned int cpu) |
698 | { |
699 | struct worker *worker = kthread_data(task), *to_wakeup = NULL; |
700 | struct global_cwq *gcwq = get_gcwq(cpu); |
701 | atomic_t *nr_running = get_gcwq_nr_running(cpu); |
702 | |
703 | if (unlikely(worker->flags & WORKER_NOT_RUNNING)) |
704 | return NULL; |
705 | |
706 | /* this can only happen on the local cpu */ |
707 | BUG_ON(cpu != raw_smp_processor_id()); |
708 | |
709 | /* |
710 | * The counterpart of the following dec_and_test, implied mb, |
711 | * worklist not empty test sequence is in insert_work(). |
712 | * Please read comment there. |
713 | * |
714 | * NOT_RUNNING is clear. This means that trustee is not in |
715 | * charge and we're running on the local cpu w/ rq lock held |
716 | * and preemption disabled, which in turn means that none else |
717 | * could be manipulating idle_list, so dereferencing idle_list |
718 | * without gcwq lock is safe. |
719 | */ |
720 | if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist)) |
721 | to_wakeup = first_worker(gcwq); |
722 | return to_wakeup ? to_wakeup->task : NULL; |
723 | } |
724 | |
725 | /** |
726 | * worker_set_flags - set worker flags and adjust nr_running accordingly |
727 | * @worker: self |
728 | * @flags: flags to set |
729 | * @wakeup: wakeup an idle worker if necessary |
730 | * |
731 | * Set @flags in @worker->flags and adjust nr_running accordingly. If |
732 | * nr_running becomes zero and @wakeup is %true, an idle worker is |
733 | * woken up. |
734 | * |
735 | * CONTEXT: |
736 | * spin_lock_irq(gcwq->lock) |
737 | */ |
738 | static inline void worker_set_flags(struct worker *worker, unsigned int flags, |
739 | bool wakeup) |
740 | { |
741 | struct global_cwq *gcwq = worker->gcwq; |
742 | |
743 | WARN_ON_ONCE(worker->task != current); |
744 | |
745 | /* |
746 | * If transitioning into NOT_RUNNING, adjust nr_running and |
747 | * wake up an idle worker as necessary if requested by |
748 | * @wakeup. |
749 | */ |
750 | if ((flags & WORKER_NOT_RUNNING) && |
751 | !(worker->flags & WORKER_NOT_RUNNING)) { |
752 | atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); |
753 | |
754 | if (wakeup) { |
755 | if (atomic_dec_and_test(nr_running) && |
756 | !list_empty(&gcwq->worklist)) |
757 | wake_up_worker(gcwq); |
758 | } else |
759 | atomic_dec(nr_running); |
760 | } |
761 | |
762 | worker->flags |= flags; |
763 | } |
764 | |
765 | /** |
766 | * worker_clr_flags - clear worker flags and adjust nr_running accordingly |
767 | * @worker: self |
768 | * @flags: flags to clear |
769 | * |
770 | * Clear @flags in @worker->flags and adjust nr_running accordingly. |
771 | * |
772 | * CONTEXT: |
773 | * spin_lock_irq(gcwq->lock) |
774 | */ |
775 | static inline void worker_clr_flags(struct worker *worker, unsigned int flags) |
776 | { |
777 | struct global_cwq *gcwq = worker->gcwq; |
778 | unsigned int oflags = worker->flags; |
779 | |
780 | WARN_ON_ONCE(worker->task != current); |
781 | |
782 | worker->flags &= ~flags; |
783 | |
784 | /* if transitioning out of NOT_RUNNING, increment nr_running */ |
785 | if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) |
786 | if (!(worker->flags & WORKER_NOT_RUNNING)) |
787 | atomic_inc(get_gcwq_nr_running(gcwq->cpu)); |
788 | } |
789 | |
790 | /** |
791 | * busy_worker_head - return the busy hash head for a work |
792 | * @gcwq: gcwq of interest |
793 | * @work: work to be hashed |
794 | * |
795 | * Return hash head of @gcwq for @work. |
796 | * |
797 | * CONTEXT: |
798 | * spin_lock_irq(gcwq->lock). |
799 | * |
800 | * RETURNS: |
801 | * Pointer to the hash head. |
802 | */ |
803 | static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, |
804 | struct work_struct *work) |
805 | { |
806 | const int base_shift = ilog2(sizeof(struct work_struct)); |
807 | unsigned long v = (unsigned long)work; |
808 | |
809 | /* simple shift and fold hash, do we need something better? */ |
810 | v >>= base_shift; |
811 | v += v >> BUSY_WORKER_HASH_ORDER; |
812 | v &= BUSY_WORKER_HASH_MASK; |
813 | |
814 | return &gcwq->busy_hash[v]; |
815 | } |
816 | |
817 | /** |
818 | * __find_worker_executing_work - find worker which is executing a work |
819 | * @gcwq: gcwq of interest |
820 | * @bwh: hash head as returned by busy_worker_head() |
821 | * @work: work to find worker for |
822 | * |
823 | * Find a worker which is executing @work on @gcwq. @bwh should be |
824 | * the hash head obtained by calling busy_worker_head() with the same |
825 | * work. |
826 | * |
827 | * CONTEXT: |
828 | * spin_lock_irq(gcwq->lock). |
829 | * |
830 | * RETURNS: |
831 | * Pointer to worker which is executing @work if found, NULL |
832 | * otherwise. |
833 | */ |
834 | static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, |
835 | struct hlist_head *bwh, |
836 | struct work_struct *work) |
837 | { |
838 | struct worker *worker; |
839 | struct hlist_node *tmp; |
840 | |
841 | hlist_for_each_entry(worker, tmp, bwh, hentry) |
842 | if (worker->current_work == work) |
843 | return worker; |
844 | return NULL; |
845 | } |
846 | |
847 | /** |
848 | * find_worker_executing_work - find worker which is executing a work |
849 | * @gcwq: gcwq of interest |
850 | * @work: work to find worker for |
851 | * |
852 | * Find a worker which is executing @work on @gcwq. This function is |
853 | * identical to __find_worker_executing_work() except that this |
854 | * function calculates @bwh itself. |
855 | * |
856 | * CONTEXT: |
857 | * spin_lock_irq(gcwq->lock). |
858 | * |
859 | * RETURNS: |
860 | * Pointer to worker which is executing @work if found, NULL |
861 | * otherwise. |
862 | */ |
863 | static struct worker *find_worker_executing_work(struct global_cwq *gcwq, |
864 | struct work_struct *work) |
865 | { |
866 | return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), |
867 | work); |
868 | } |
869 | |
870 | /** |
871 | * gcwq_determine_ins_pos - find insertion position |
872 | * @gcwq: gcwq of interest |
873 | * @cwq: cwq a work is being queued for |
874 | * |
875 | * A work for @cwq is about to be queued on @gcwq, determine insertion |
876 | * position for the work. If @cwq is for HIGHPRI wq, the work is |
877 | * queued at the head of the queue but in FIFO order with respect to |
878 | * other HIGHPRI works; otherwise, at the end of the queue. This |
879 | * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that |
880 | * there are HIGHPRI works pending. |
881 | * |
882 | * CONTEXT: |
883 | * spin_lock_irq(gcwq->lock). |
884 | * |
885 | * RETURNS: |
886 | * Pointer to inserstion position. |
887 | */ |
888 | static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq, |
889 | struct cpu_workqueue_struct *cwq) |
890 | { |
891 | struct work_struct *twork; |
892 | |
893 | if (likely(!(cwq->wq->flags & WQ_HIGHPRI))) |
894 | return &gcwq->worklist; |
895 | |
896 | list_for_each_entry(twork, &gcwq->worklist, entry) { |
897 | struct cpu_workqueue_struct *tcwq = get_work_cwq(twork); |
898 | |
899 | if (!(tcwq->wq->flags & WQ_HIGHPRI)) |
900 | break; |
901 | } |
902 | |
903 | gcwq->flags |= GCWQ_HIGHPRI_PENDING; |
904 | return &twork->entry; |
905 | } |
906 | |
907 | /** |
908 | * insert_work - insert a work into gcwq |
909 | * @cwq: cwq @work belongs to |
910 | * @work: work to insert |
911 | * @head: insertion point |
912 | * @extra_flags: extra WORK_STRUCT_* flags to set |
913 | * |
914 | * Insert @work which belongs to @cwq into @gcwq after @head. |
915 | * @extra_flags is or'd to work_struct flags. |
916 | * |
917 | * CONTEXT: |
918 | * spin_lock_irq(gcwq->lock). |
919 | */ |
920 | static void insert_work(struct cpu_workqueue_struct *cwq, |
921 | struct work_struct *work, struct list_head *head, |
922 | unsigned int extra_flags) |
923 | { |
924 | struct global_cwq *gcwq = cwq->gcwq; |
925 | |
926 | /* we own @work, set data and link */ |
927 | set_work_cwq(work, cwq, extra_flags); |
928 | |
929 | /* |
930 | * Ensure that we get the right work->data if we see the |
931 | * result of list_add() below, see try_to_grab_pending(). |
932 | */ |
933 | smp_wmb(); |
934 | |
935 | list_add_tail(&work->entry, head); |
936 | |
937 | /* |
938 | * Ensure either worker_sched_deactivated() sees the above |
939 | * list_add_tail() or we see zero nr_running to avoid workers |
940 | * lying around lazily while there are works to be processed. |
941 | */ |
942 | smp_mb(); |
943 | |
944 | if (__need_more_worker(gcwq)) |
945 | wake_up_worker(gcwq); |
946 | } |
947 | |
948 | static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, |
949 | struct work_struct *work) |
950 | { |
951 | struct global_cwq *gcwq; |
952 | struct cpu_workqueue_struct *cwq; |
953 | struct list_head *worklist; |
954 | unsigned int work_flags; |
955 | unsigned long flags; |
956 | |
957 | debug_work_activate(work); |
958 | |
959 | if (WARN_ON_ONCE(wq->flags & WQ_DYING)) |
960 | return; |
961 | |
962 | /* determine gcwq to use */ |
963 | if (!(wq->flags & WQ_UNBOUND)) { |
964 | struct global_cwq *last_gcwq; |
965 | |
966 | if (unlikely(cpu == WORK_CPU_UNBOUND)) |
967 | cpu = raw_smp_processor_id(); |
968 | |
969 | /* |
970 | * It's multi cpu. If @wq is non-reentrant and @work |
971 | * was previously on a different cpu, it might still |
972 | * be running there, in which case the work needs to |
973 | * be queued on that cpu to guarantee non-reentrance. |
974 | */ |
975 | gcwq = get_gcwq(cpu); |
976 | if (wq->flags & WQ_NON_REENTRANT && |
977 | (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { |
978 | struct worker *worker; |
979 | |
980 | spin_lock_irqsave(&last_gcwq->lock, flags); |
981 | |
982 | worker = find_worker_executing_work(last_gcwq, work); |
983 | |
984 | if (worker && worker->current_cwq->wq == wq) |
985 | gcwq = last_gcwq; |
986 | else { |
987 | /* meh... not running there, queue here */ |
988 | spin_unlock_irqrestore(&last_gcwq->lock, flags); |
989 | spin_lock_irqsave(&gcwq->lock, flags); |
990 | } |
991 | } else |
992 | spin_lock_irqsave(&gcwq->lock, flags); |
993 | } else { |
994 | gcwq = get_gcwq(WORK_CPU_UNBOUND); |
995 | spin_lock_irqsave(&gcwq->lock, flags); |
996 | } |
997 | |
998 | /* gcwq determined, get cwq and queue */ |
999 | cwq = get_cwq(gcwq->cpu, wq); |
1000 | |
1001 | BUG_ON(!list_empty(&work->entry)); |
1002 | |
1003 | cwq->nr_in_flight[cwq->work_color]++; |
1004 | work_flags = work_color_to_flags(cwq->work_color); |
1005 | |
1006 | if (likely(cwq->nr_active < cwq->max_active)) { |
1007 | cwq->nr_active++; |
1008 | worklist = gcwq_determine_ins_pos(gcwq, cwq); |
1009 | } else { |
1010 | work_flags |= WORK_STRUCT_DELAYED; |
1011 | worklist = &cwq->delayed_works; |
1012 | } |
1013 | |
1014 | insert_work(cwq, work, worklist, work_flags); |
1015 | |
1016 | spin_unlock_irqrestore(&gcwq->lock, flags); |
1017 | } |
1018 | |
1019 | /** |
1020 | * queue_work - queue work on a workqueue |
1021 | * @wq: workqueue to use |
1022 | * @work: work to queue |
1023 | * |
1024 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1025 | * |
1026 | * We queue the work to the CPU on which it was submitted, but if the CPU dies |
1027 | * it can be processed by another CPU. |
1028 | */ |
1029 | int queue_work(struct workqueue_struct *wq, struct work_struct *work) |
1030 | { |
1031 | int ret; |
1032 | |
1033 | ret = queue_work_on(get_cpu(), wq, work); |
1034 | put_cpu(); |
1035 | |
1036 | return ret; |
1037 | } |
1038 | EXPORT_SYMBOL_GPL(queue_work); |
1039 | |
1040 | /** |
1041 | * queue_work_on - queue work on specific cpu |
1042 | * @cpu: CPU number to execute work on |
1043 | * @wq: workqueue to use |
1044 | * @work: work to queue |
1045 | * |
1046 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1047 | * |
1048 | * We queue the work to a specific CPU, the caller must ensure it |
1049 | * can't go away. |
1050 | */ |
1051 | int |
1052 | queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) |
1053 | { |
1054 | int ret = 0; |
1055 | |
1056 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1057 | __queue_work(cpu, wq, work); |
1058 | ret = 1; |
1059 | } |
1060 | return ret; |
1061 | } |
1062 | EXPORT_SYMBOL_GPL(queue_work_on); |
1063 | |
1064 | static void delayed_work_timer_fn(unsigned long __data) |
1065 | { |
1066 | struct delayed_work *dwork = (struct delayed_work *)__data; |
1067 | struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); |
1068 | |
1069 | __queue_work(smp_processor_id(), cwq->wq, &dwork->work); |
1070 | } |
1071 | |
1072 | /** |
1073 | * queue_delayed_work - queue work on a workqueue after delay |
1074 | * @wq: workqueue to use |
1075 | * @dwork: delayable work to queue |
1076 | * @delay: number of jiffies to wait before queueing |
1077 | * |
1078 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1079 | */ |
1080 | int queue_delayed_work(struct workqueue_struct *wq, |
1081 | struct delayed_work *dwork, unsigned long delay) |
1082 | { |
1083 | if (delay == 0) |
1084 | return queue_work(wq, &dwork->work); |
1085 | |
1086 | return queue_delayed_work_on(-1, wq, dwork, delay); |
1087 | } |
1088 | EXPORT_SYMBOL_GPL(queue_delayed_work); |
1089 | |
1090 | /** |
1091 | * queue_delayed_work_on - queue work on specific CPU after delay |
1092 | * @cpu: CPU number to execute work on |
1093 | * @wq: workqueue to use |
1094 | * @dwork: work to queue |
1095 | * @delay: number of jiffies to wait before queueing |
1096 | * |
1097 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1098 | */ |
1099 | int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
1100 | struct delayed_work *dwork, unsigned long delay) |
1101 | { |
1102 | int ret = 0; |
1103 | struct timer_list *timer = &dwork->timer; |
1104 | struct work_struct *work = &dwork->work; |
1105 | |
1106 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1107 | unsigned int lcpu; |
1108 | |
1109 | BUG_ON(timer_pending(timer)); |
1110 | BUG_ON(!list_empty(&work->entry)); |
1111 | |
1112 | timer_stats_timer_set_start_info(&dwork->timer); |
1113 | |
1114 | /* |
1115 | * This stores cwq for the moment, for the timer_fn. |
1116 | * Note that the work's gcwq is preserved to allow |
1117 | * reentrance detection for delayed works. |
1118 | */ |
1119 | if (!(wq->flags & WQ_UNBOUND)) { |
1120 | struct global_cwq *gcwq = get_work_gcwq(work); |
1121 | |
1122 | if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND) |
1123 | lcpu = gcwq->cpu; |
1124 | else |
1125 | lcpu = raw_smp_processor_id(); |
1126 | } else |
1127 | lcpu = WORK_CPU_UNBOUND; |
1128 | |
1129 | set_work_cwq(work, get_cwq(lcpu, wq), 0); |
1130 | |
1131 | timer->expires = jiffies + delay; |
1132 | timer->data = (unsigned long)dwork; |
1133 | timer->function = delayed_work_timer_fn; |
1134 | |
1135 | if (unlikely(cpu >= 0)) |
1136 | add_timer_on(timer, cpu); |
1137 | else |
1138 | add_timer(timer); |
1139 | ret = 1; |
1140 | } |
1141 | return ret; |
1142 | } |
1143 | EXPORT_SYMBOL_GPL(queue_delayed_work_on); |
1144 | |
1145 | /** |
1146 | * worker_enter_idle - enter idle state |
1147 | * @worker: worker which is entering idle state |
1148 | * |
1149 | * @worker is entering idle state. Update stats and idle timer if |
1150 | * necessary. |
1151 | * |
1152 | * LOCKING: |
1153 | * spin_lock_irq(gcwq->lock). |
1154 | */ |
1155 | static void worker_enter_idle(struct worker *worker) |
1156 | { |
1157 | struct global_cwq *gcwq = worker->gcwq; |
1158 | |
1159 | BUG_ON(worker->flags & WORKER_IDLE); |
1160 | BUG_ON(!list_empty(&worker->entry) && |
1161 | (worker->hentry.next || worker->hentry.pprev)); |
1162 | |
1163 | /* can't use worker_set_flags(), also called from start_worker() */ |
1164 | worker->flags |= WORKER_IDLE; |
1165 | gcwq->nr_idle++; |
1166 | worker->last_active = jiffies; |
1167 | |
1168 | /* idle_list is LIFO */ |
1169 | list_add(&worker->entry, &gcwq->idle_list); |
1170 | |
1171 | if (likely(!(worker->flags & WORKER_ROGUE))) { |
1172 | if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer)) |
1173 | mod_timer(&gcwq->idle_timer, |
1174 | jiffies + IDLE_WORKER_TIMEOUT); |
1175 | } else |
1176 | wake_up_all(&gcwq->trustee_wait); |
1177 | |
1178 | /* sanity check nr_running */ |
1179 | WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle && |
1180 | atomic_read(get_gcwq_nr_running(gcwq->cpu))); |
1181 | } |
1182 | |
1183 | /** |
1184 | * worker_leave_idle - leave idle state |
1185 | * @worker: worker which is leaving idle state |
1186 | * |
1187 | * @worker is leaving idle state. Update stats. |
1188 | * |
1189 | * LOCKING: |
1190 | * spin_lock_irq(gcwq->lock). |
1191 | */ |
1192 | static void worker_leave_idle(struct worker *worker) |
1193 | { |
1194 | struct global_cwq *gcwq = worker->gcwq; |
1195 | |
1196 | BUG_ON(!(worker->flags & WORKER_IDLE)); |
1197 | worker_clr_flags(worker, WORKER_IDLE); |
1198 | gcwq->nr_idle--; |
1199 | list_del_init(&worker->entry); |
1200 | } |
1201 | |
1202 | /** |
1203 | * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq |
1204 | * @worker: self |
1205 | * |
1206 | * Works which are scheduled while the cpu is online must at least be |
1207 | * scheduled to a worker which is bound to the cpu so that if they are |
1208 | * flushed from cpu callbacks while cpu is going down, they are |
1209 | * guaranteed to execute on the cpu. |
1210 | * |
1211 | * This function is to be used by rogue workers and rescuers to bind |
1212 | * themselves to the target cpu and may race with cpu going down or |
1213 | * coming online. kthread_bind() can't be used because it may put the |
1214 | * worker to already dead cpu and set_cpus_allowed_ptr() can't be used |
1215 | * verbatim as it's best effort and blocking and gcwq may be |
1216 | * [dis]associated in the meantime. |
1217 | * |
1218 | * This function tries set_cpus_allowed() and locks gcwq and verifies |
1219 | * the binding against GCWQ_DISASSOCIATED which is set during |
1220 | * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters |
1221 | * idle state or fetches works without dropping lock, it can guarantee |
1222 | * the scheduling requirement described in the first paragraph. |
1223 | * |
1224 | * CONTEXT: |
1225 | * Might sleep. Called without any lock but returns with gcwq->lock |
1226 | * held. |
1227 | * |
1228 | * RETURNS: |
1229 | * %true if the associated gcwq is online (@worker is successfully |
1230 | * bound), %false if offline. |
1231 | */ |
1232 | static bool worker_maybe_bind_and_lock(struct worker *worker) |
1233 | __acquires(&gcwq->lock) |
1234 | { |
1235 | struct global_cwq *gcwq = worker->gcwq; |
1236 | struct task_struct *task = worker->task; |
1237 | |
1238 | while (true) { |
1239 | /* |
1240 | * The following call may fail, succeed or succeed |
1241 | * without actually migrating the task to the cpu if |
1242 | * it races with cpu hotunplug operation. Verify |
1243 | * against GCWQ_DISASSOCIATED. |
1244 | */ |
1245 | if (!(gcwq->flags & GCWQ_DISASSOCIATED)) |
1246 | set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); |
1247 | |
1248 | spin_lock_irq(&gcwq->lock); |
1249 | if (gcwq->flags & GCWQ_DISASSOCIATED) |
1250 | return false; |
1251 | if (task_cpu(task) == gcwq->cpu && |
1252 | cpumask_equal(¤t->cpus_allowed, |
1253 | get_cpu_mask(gcwq->cpu))) |
1254 | return true; |
1255 | spin_unlock_irq(&gcwq->lock); |
1256 | |
1257 | /* CPU has come up inbetween, retry migration */ |
1258 | cpu_relax(); |
1259 | } |
1260 | } |
1261 | |
1262 | /* |
1263 | * Function for worker->rebind_work used to rebind rogue busy workers |
1264 | * to the associated cpu which is coming back online. This is |
1265 | * scheduled by cpu up but can race with other cpu hotplug operations |
1266 | * and may be executed twice without intervening cpu down. |
1267 | */ |
1268 | static void worker_rebind_fn(struct work_struct *work) |
1269 | { |
1270 | struct worker *worker = container_of(work, struct worker, rebind_work); |
1271 | struct global_cwq *gcwq = worker->gcwq; |
1272 | |
1273 | if (worker_maybe_bind_and_lock(worker)) |
1274 | worker_clr_flags(worker, WORKER_REBIND); |
1275 | |
1276 | spin_unlock_irq(&gcwq->lock); |
1277 | } |
1278 | |
1279 | static struct worker *alloc_worker(void) |
1280 | { |
1281 | struct worker *worker; |
1282 | |
1283 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); |
1284 | if (worker) { |
1285 | INIT_LIST_HEAD(&worker->entry); |
1286 | INIT_LIST_HEAD(&worker->scheduled); |
1287 | INIT_WORK(&worker->rebind_work, worker_rebind_fn); |
1288 | /* on creation a worker is in !idle && prep state */ |
1289 | worker->flags = WORKER_PREP; |
1290 | } |
1291 | return worker; |
1292 | } |
1293 | |
1294 | /** |
1295 | * create_worker - create a new workqueue worker |
1296 | * @gcwq: gcwq the new worker will belong to |
1297 | * @bind: whether to set affinity to @cpu or not |
1298 | * |
1299 | * Create a new worker which is bound to @gcwq. The returned worker |
1300 | * can be started by calling start_worker() or destroyed using |
1301 | * destroy_worker(). |
1302 | * |
1303 | * CONTEXT: |
1304 | * Might sleep. Does GFP_KERNEL allocations. |
1305 | * |
1306 | * RETURNS: |
1307 | * Pointer to the newly created worker. |
1308 | */ |
1309 | static struct worker *create_worker(struct global_cwq *gcwq, bool bind) |
1310 | { |
1311 | bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND; |
1312 | struct worker *worker = NULL; |
1313 | int id = -1; |
1314 | |
1315 | spin_lock_irq(&gcwq->lock); |
1316 | while (ida_get_new(&gcwq->worker_ida, &id)) { |
1317 | spin_unlock_irq(&gcwq->lock); |
1318 | if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) |
1319 | goto fail; |
1320 | spin_lock_irq(&gcwq->lock); |
1321 | } |
1322 | spin_unlock_irq(&gcwq->lock); |
1323 | |
1324 | worker = alloc_worker(); |
1325 | if (!worker) |
1326 | goto fail; |
1327 | |
1328 | worker->gcwq = gcwq; |
1329 | worker->id = id; |
1330 | |
1331 | if (!on_unbound_cpu) |
1332 | worker->task = kthread_create(worker_thread, worker, |
1333 | "kworker/%u:%d", gcwq->cpu, id); |
1334 | else |
1335 | worker->task = kthread_create(worker_thread, worker, |
1336 | "kworker/u:%d", id); |
1337 | if (IS_ERR(worker->task)) |
1338 | goto fail; |
1339 | |
1340 | /* |
1341 | * A rogue worker will become a regular one if CPU comes |
1342 | * online later on. Make sure every worker has |
1343 | * PF_THREAD_BOUND set. |
1344 | */ |
1345 | if (bind && !on_unbound_cpu) |
1346 | kthread_bind(worker->task, gcwq->cpu); |
1347 | else { |
1348 | worker->task->flags |= PF_THREAD_BOUND; |
1349 | if (on_unbound_cpu) |
1350 | worker->flags |= WORKER_UNBOUND; |
1351 | } |
1352 | |
1353 | return worker; |
1354 | fail: |
1355 | if (id >= 0) { |
1356 | spin_lock_irq(&gcwq->lock); |
1357 | ida_remove(&gcwq->worker_ida, id); |
1358 | spin_unlock_irq(&gcwq->lock); |
1359 | } |
1360 | kfree(worker); |
1361 | return NULL; |
1362 | } |
1363 | |
1364 | /** |
1365 | * start_worker - start a newly created worker |
1366 | * @worker: worker to start |
1367 | * |
1368 | * Make the gcwq aware of @worker and start it. |
1369 | * |
1370 | * CONTEXT: |
1371 | * spin_lock_irq(gcwq->lock). |
1372 | */ |
1373 | static void start_worker(struct worker *worker) |
1374 | { |
1375 | worker->flags |= WORKER_STARTED; |
1376 | worker->gcwq->nr_workers++; |
1377 | worker_enter_idle(worker); |
1378 | wake_up_process(worker->task); |
1379 | } |
1380 | |
1381 | /** |
1382 | * destroy_worker - destroy a workqueue worker |
1383 | * @worker: worker to be destroyed |
1384 | * |
1385 | * Destroy @worker and adjust @gcwq stats accordingly. |
1386 | * |
1387 | * CONTEXT: |
1388 | * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
1389 | */ |
1390 | static void destroy_worker(struct worker *worker) |
1391 | { |
1392 | struct global_cwq *gcwq = worker->gcwq; |
1393 | int id = worker->id; |
1394 | |
1395 | /* sanity check frenzy */ |
1396 | BUG_ON(worker->current_work); |
1397 | BUG_ON(!list_empty(&worker->scheduled)); |
1398 | |
1399 | if (worker->flags & WORKER_STARTED) |
1400 | gcwq->nr_workers--; |
1401 | if (worker->flags & WORKER_IDLE) |
1402 | gcwq->nr_idle--; |
1403 | |
1404 | list_del_init(&worker->entry); |
1405 | worker->flags |= WORKER_DIE; |
1406 | |
1407 | spin_unlock_irq(&gcwq->lock); |
1408 | |
1409 | kthread_stop(worker->task); |
1410 | kfree(worker); |
1411 | |
1412 | spin_lock_irq(&gcwq->lock); |
1413 | ida_remove(&gcwq->worker_ida, id); |
1414 | } |
1415 | |
1416 | static void idle_worker_timeout(unsigned long __gcwq) |
1417 | { |
1418 | struct global_cwq *gcwq = (void *)__gcwq; |
1419 | |
1420 | spin_lock_irq(&gcwq->lock); |
1421 | |
1422 | if (too_many_workers(gcwq)) { |
1423 | struct worker *worker; |
1424 | unsigned long expires; |
1425 | |
1426 | /* idle_list is kept in LIFO order, check the last one */ |
1427 | worker = list_entry(gcwq->idle_list.prev, struct worker, entry); |
1428 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
1429 | |
1430 | if (time_before(jiffies, expires)) |
1431 | mod_timer(&gcwq->idle_timer, expires); |
1432 | else { |
1433 | /* it's been idle for too long, wake up manager */ |
1434 | gcwq->flags |= GCWQ_MANAGE_WORKERS; |
1435 | wake_up_worker(gcwq); |
1436 | } |
1437 | } |
1438 | |
1439 | spin_unlock_irq(&gcwq->lock); |
1440 | } |
1441 | |
1442 | static bool send_mayday(struct work_struct *work) |
1443 | { |
1444 | struct cpu_workqueue_struct *cwq = get_work_cwq(work); |
1445 | struct workqueue_struct *wq = cwq->wq; |
1446 | unsigned int cpu; |
1447 | |
1448 | if (!(wq->flags & WQ_RESCUER)) |
1449 | return false; |
1450 | |
1451 | /* mayday mayday mayday */ |
1452 | cpu = cwq->gcwq->cpu; |
1453 | /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ |
1454 | if (cpu == WORK_CPU_UNBOUND) |
1455 | cpu = 0; |
1456 | if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) |
1457 | wake_up_process(wq->rescuer->task); |
1458 | return true; |
1459 | } |
1460 | |
1461 | static void gcwq_mayday_timeout(unsigned long __gcwq) |
1462 | { |
1463 | struct global_cwq *gcwq = (void *)__gcwq; |
1464 | struct work_struct *work; |
1465 | |
1466 | spin_lock_irq(&gcwq->lock); |
1467 | |
1468 | if (need_to_create_worker(gcwq)) { |
1469 | /* |
1470 | * We've been trying to create a new worker but |
1471 | * haven't been successful. We might be hitting an |
1472 | * allocation deadlock. Send distress signals to |
1473 | * rescuers. |
1474 | */ |
1475 | list_for_each_entry(work, &gcwq->worklist, entry) |
1476 | send_mayday(work); |
1477 | } |
1478 | |
1479 | spin_unlock_irq(&gcwq->lock); |
1480 | |
1481 | mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL); |
1482 | } |
1483 | |
1484 | /** |
1485 | * maybe_create_worker - create a new worker if necessary |
1486 | * @gcwq: gcwq to create a new worker for |
1487 | * |
1488 | * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to |
1489 | * have at least one idle worker on return from this function. If |
1490 | * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is |
1491 | * sent to all rescuers with works scheduled on @gcwq to resolve |
1492 | * possible allocation deadlock. |
1493 | * |
1494 | * On return, need_to_create_worker() is guaranteed to be false and |
1495 | * may_start_working() true. |
1496 | * |
1497 | * LOCKING: |
1498 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
1499 | * multiple times. Does GFP_KERNEL allocations. Called only from |
1500 | * manager. |
1501 | * |
1502 | * RETURNS: |
1503 | * false if no action was taken and gcwq->lock stayed locked, true |
1504 | * otherwise. |
1505 | */ |
1506 | static bool maybe_create_worker(struct global_cwq *gcwq) |
1507 | __releases(&gcwq->lock) |
1508 | __acquires(&gcwq->lock) |
1509 | { |
1510 | if (!need_to_create_worker(gcwq)) |
1511 | return false; |
1512 | restart: |
1513 | spin_unlock_irq(&gcwq->lock); |
1514 | |
1515 | /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ |
1516 | mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); |
1517 | |
1518 | while (true) { |
1519 | struct worker *worker; |
1520 | |
1521 | worker = create_worker(gcwq, true); |
1522 | if (worker) { |
1523 | del_timer_sync(&gcwq->mayday_timer); |
1524 | spin_lock_irq(&gcwq->lock); |
1525 | start_worker(worker); |
1526 | BUG_ON(need_to_create_worker(gcwq)); |
1527 | return true; |
1528 | } |
1529 | |
1530 | if (!need_to_create_worker(gcwq)) |
1531 | break; |
1532 | |
1533 | __set_current_state(TASK_INTERRUPTIBLE); |
1534 | schedule_timeout(CREATE_COOLDOWN); |
1535 | |
1536 | if (!need_to_create_worker(gcwq)) |
1537 | break; |
1538 | } |
1539 | |
1540 | del_timer_sync(&gcwq->mayday_timer); |
1541 | spin_lock_irq(&gcwq->lock); |
1542 | if (need_to_create_worker(gcwq)) |
1543 | goto restart; |
1544 | return true; |
1545 | } |
1546 | |
1547 | /** |
1548 | * maybe_destroy_worker - destroy workers which have been idle for a while |
1549 | * @gcwq: gcwq to destroy workers for |
1550 | * |
1551 | * Destroy @gcwq workers which have been idle for longer than |
1552 | * IDLE_WORKER_TIMEOUT. |
1553 | * |
1554 | * LOCKING: |
1555 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
1556 | * multiple times. Called only from manager. |
1557 | * |
1558 | * RETURNS: |
1559 | * false if no action was taken and gcwq->lock stayed locked, true |
1560 | * otherwise. |
1561 | */ |
1562 | static bool maybe_destroy_workers(struct global_cwq *gcwq) |
1563 | { |
1564 | bool ret = false; |
1565 | |
1566 | while (too_many_workers(gcwq)) { |
1567 | struct worker *worker; |
1568 | unsigned long expires; |
1569 | |
1570 | worker = list_entry(gcwq->idle_list.prev, struct worker, entry); |
1571 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
1572 | |
1573 | if (time_before(jiffies, expires)) { |
1574 | mod_timer(&gcwq->idle_timer, expires); |
1575 | break; |
1576 | } |
1577 | |
1578 | destroy_worker(worker); |
1579 | ret = true; |
1580 | } |
1581 | |
1582 | return ret; |
1583 | } |
1584 | |
1585 | /** |
1586 | * manage_workers - manage worker pool |
1587 | * @worker: self |
1588 | * |
1589 | * Assume the manager role and manage gcwq worker pool @worker belongs |
1590 | * to. At any given time, there can be only zero or one manager per |
1591 | * gcwq. The exclusion is handled automatically by this function. |
1592 | * |
1593 | * The caller can safely start processing works on false return. On |
1594 | * true return, it's guaranteed that need_to_create_worker() is false |
1595 | * and may_start_working() is true. |
1596 | * |
1597 | * CONTEXT: |
1598 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
1599 | * multiple times. Does GFP_KERNEL allocations. |
1600 | * |
1601 | * RETURNS: |
1602 | * false if no action was taken and gcwq->lock stayed locked, true if |
1603 | * some action was taken. |
1604 | */ |
1605 | static bool manage_workers(struct worker *worker) |
1606 | { |
1607 | struct global_cwq *gcwq = worker->gcwq; |
1608 | bool ret = false; |
1609 | |
1610 | if (gcwq->flags & GCWQ_MANAGING_WORKERS) |
1611 | return ret; |
1612 | |
1613 | gcwq->flags &= ~GCWQ_MANAGE_WORKERS; |
1614 | gcwq->flags |= GCWQ_MANAGING_WORKERS; |
1615 | |
1616 | /* |
1617 | * Destroy and then create so that may_start_working() is true |
1618 | * on return. |
1619 | */ |
1620 | ret |= maybe_destroy_workers(gcwq); |
1621 | ret |= maybe_create_worker(gcwq); |
1622 | |
1623 | gcwq->flags &= ~GCWQ_MANAGING_WORKERS; |
1624 | |
1625 | /* |
1626 | * The trustee might be waiting to take over the manager |
1627 | * position, tell it we're done. |
1628 | */ |
1629 | if (unlikely(gcwq->trustee)) |
1630 | wake_up_all(&gcwq->trustee_wait); |
1631 | |
1632 | return ret; |
1633 | } |
1634 | |
1635 | /** |
1636 | * move_linked_works - move linked works to a list |
1637 | * @work: start of series of works to be scheduled |
1638 | * @head: target list to append @work to |
1639 | * @nextp: out paramter for nested worklist walking |
1640 | * |
1641 | * Schedule linked works starting from @work to @head. Work series to |
1642 | * be scheduled starts at @work and includes any consecutive work with |
1643 | * WORK_STRUCT_LINKED set in its predecessor. |
1644 | * |
1645 | * If @nextp is not NULL, it's updated to point to the next work of |
1646 | * the last scheduled work. This allows move_linked_works() to be |
1647 | * nested inside outer list_for_each_entry_safe(). |
1648 | * |
1649 | * CONTEXT: |
1650 | * spin_lock_irq(gcwq->lock). |
1651 | */ |
1652 | static void move_linked_works(struct work_struct *work, struct list_head *head, |
1653 | struct work_struct **nextp) |
1654 | { |
1655 | struct work_struct *n; |
1656 | |
1657 | /* |
1658 | * Linked worklist will always end before the end of the list, |
1659 | * use NULL for list head. |
1660 | */ |
1661 | list_for_each_entry_safe_from(work, n, NULL, entry) { |
1662 | list_move_tail(&work->entry, head); |
1663 | if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) |
1664 | break; |
1665 | } |
1666 | |
1667 | /* |
1668 | * If we're already inside safe list traversal and have moved |
1669 | * multiple works to the scheduled queue, the next position |
1670 | * needs to be updated. |
1671 | */ |
1672 | if (nextp) |
1673 | *nextp = n; |
1674 | } |
1675 | |
1676 | static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) |
1677 | { |
1678 | struct work_struct *work = list_first_entry(&cwq->delayed_works, |
1679 | struct work_struct, entry); |
1680 | struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq); |
1681 | |
1682 | move_linked_works(work, pos, NULL); |
1683 | __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); |
1684 | cwq->nr_active++; |
1685 | } |
1686 | |
1687 | /** |
1688 | * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight |
1689 | * @cwq: cwq of interest |
1690 | * @color: color of work which left the queue |
1691 | * @delayed: for a delayed work |
1692 | * |
1693 | * A work either has completed or is removed from pending queue, |
1694 | * decrement nr_in_flight of its cwq and handle workqueue flushing. |
1695 | * |
1696 | * CONTEXT: |
1697 | * spin_lock_irq(gcwq->lock). |
1698 | */ |
1699 | static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color, |
1700 | bool delayed) |
1701 | { |
1702 | /* ignore uncolored works */ |
1703 | if (color == WORK_NO_COLOR) |
1704 | return; |
1705 | |
1706 | cwq->nr_in_flight[color]--; |
1707 | |
1708 | if (!delayed) { |
1709 | cwq->nr_active--; |
1710 | if (!list_empty(&cwq->delayed_works)) { |
1711 | /* one down, submit a delayed one */ |
1712 | if (cwq->nr_active < cwq->max_active) |
1713 | cwq_activate_first_delayed(cwq); |
1714 | } |
1715 | } |
1716 | |
1717 | /* is flush in progress and are we at the flushing tip? */ |
1718 | if (likely(cwq->flush_color != color)) |
1719 | return; |
1720 | |
1721 | /* are there still in-flight works? */ |
1722 | if (cwq->nr_in_flight[color]) |
1723 | return; |
1724 | |
1725 | /* this cwq is done, clear flush_color */ |
1726 | cwq->flush_color = -1; |
1727 | |
1728 | /* |
1729 | * If this was the last cwq, wake up the first flusher. It |
1730 | * will handle the rest. |
1731 | */ |
1732 | if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) |
1733 | complete(&cwq->wq->first_flusher->done); |
1734 | } |
1735 | |
1736 | /** |
1737 | * process_one_work - process single work |
1738 | * @worker: self |
1739 | * @work: work to process |
1740 | * |
1741 | * Process @work. This function contains all the logics necessary to |
1742 | * process a single work including synchronization against and |
1743 | * interaction with other workers on the same cpu, queueing and |
1744 | * flushing. As long as context requirement is met, any worker can |
1745 | * call this function to process a work. |
1746 | * |
1747 | * CONTEXT: |
1748 | * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
1749 | */ |
1750 | static void process_one_work(struct worker *worker, struct work_struct *work) |
1751 | __releases(&gcwq->lock) |
1752 | __acquires(&gcwq->lock) |
1753 | { |
1754 | struct cpu_workqueue_struct *cwq = get_work_cwq(work); |
1755 | struct global_cwq *gcwq = cwq->gcwq; |
1756 | struct hlist_head *bwh = busy_worker_head(gcwq, work); |
1757 | bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; |
1758 | work_func_t f = work->func; |
1759 | int work_color; |
1760 | struct worker *collision; |
1761 | #ifdef CONFIG_LOCKDEP |
1762 | /* |
1763 | * It is permissible to free the struct work_struct from |
1764 | * inside the function that is called from it, this we need to |
1765 | * take into account for lockdep too. To avoid bogus "held |
1766 | * lock freed" warnings as well as problems when looking into |
1767 | * work->lockdep_map, make a copy and use that here. |
1768 | */ |
1769 | struct lockdep_map lockdep_map = work->lockdep_map; |
1770 | #endif |
1771 | /* |
1772 | * A single work shouldn't be executed concurrently by |
1773 | * multiple workers on a single cpu. Check whether anyone is |
1774 | * already processing the work. If so, defer the work to the |
1775 | * currently executing one. |
1776 | */ |
1777 | collision = __find_worker_executing_work(gcwq, bwh, work); |
1778 | if (unlikely(collision)) { |
1779 | move_linked_works(work, &collision->scheduled, NULL); |
1780 | return; |
1781 | } |
1782 | |
1783 | /* claim and process */ |
1784 | debug_work_deactivate(work); |
1785 | hlist_add_head(&worker->hentry, bwh); |
1786 | worker->current_work = work; |
1787 | worker->current_cwq = cwq; |
1788 | work_color = get_work_color(work); |
1789 | |
1790 | /* record the current cpu number in the work data and dequeue */ |
1791 | set_work_cpu(work, gcwq->cpu); |
1792 | list_del_init(&work->entry); |
1793 | |
1794 | /* |
1795 | * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI, |
1796 | * wake up another worker; otherwise, clear HIGHPRI_PENDING. |
1797 | */ |
1798 | if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) { |
1799 | struct work_struct *nwork = list_first_entry(&gcwq->worklist, |
1800 | struct work_struct, entry); |
1801 | |
1802 | if (!list_empty(&gcwq->worklist) && |
1803 | get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI) |
1804 | wake_up_worker(gcwq); |
1805 | else |
1806 | gcwq->flags &= ~GCWQ_HIGHPRI_PENDING; |
1807 | } |
1808 | |
1809 | /* |
1810 | * CPU intensive works don't participate in concurrency |
1811 | * management. They're the scheduler's responsibility. |
1812 | */ |
1813 | if (unlikely(cpu_intensive)) |
1814 | worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); |
1815 | |
1816 | spin_unlock_irq(&gcwq->lock); |
1817 | |
1818 | work_clear_pending(work); |
1819 | lock_map_acquire(&cwq->wq->lockdep_map); |
1820 | lock_map_acquire(&lockdep_map); |
1821 | trace_workqueue_execute_start(work); |
1822 | f(work); |
1823 | /* |
1824 | * While we must be careful to not use "work" after this, the trace |
1825 | * point will only record its address. |
1826 | */ |
1827 | trace_workqueue_execute_end(work); |
1828 | lock_map_release(&lockdep_map); |
1829 | lock_map_release(&cwq->wq->lockdep_map); |
1830 | |
1831 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { |
1832 | printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " |
1833 | "%s/0x%08x/%d\n", |
1834 | current->comm, preempt_count(), task_pid_nr(current)); |
1835 | printk(KERN_ERR " last function: "); |
1836 | print_symbol("%s\n", (unsigned long)f); |
1837 | debug_show_held_locks(current); |
1838 | dump_stack(); |
1839 | } |
1840 | |
1841 | spin_lock_irq(&gcwq->lock); |
1842 | |
1843 | /* clear cpu intensive status */ |
1844 | if (unlikely(cpu_intensive)) |
1845 | worker_clr_flags(worker, WORKER_CPU_INTENSIVE); |
1846 | |
1847 | /* we're done with it, release */ |
1848 | hlist_del_init(&worker->hentry); |
1849 | worker->current_work = NULL; |
1850 | worker->current_cwq = NULL; |
1851 | cwq_dec_nr_in_flight(cwq, work_color, false); |
1852 | } |
1853 | |
1854 | /** |
1855 | * process_scheduled_works - process scheduled works |
1856 | * @worker: self |
1857 | * |
1858 | * Process all scheduled works. Please note that the scheduled list |
1859 | * may change while processing a work, so this function repeatedly |
1860 | * fetches a work from the top and executes it. |
1861 | * |
1862 | * CONTEXT: |
1863 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
1864 | * multiple times. |
1865 | */ |
1866 | static void process_scheduled_works(struct worker *worker) |
1867 | { |
1868 | while (!list_empty(&worker->scheduled)) { |
1869 | struct work_struct *work = list_first_entry(&worker->scheduled, |
1870 | struct work_struct, entry); |
1871 | process_one_work(worker, work); |
1872 | } |
1873 | } |
1874 | |
1875 | /** |
1876 | * worker_thread - the worker thread function |
1877 | * @__worker: self |
1878 | * |
1879 | * The gcwq worker thread function. There's a single dynamic pool of |
1880 | * these per each cpu. These workers process all works regardless of |
1881 | * their specific target workqueue. The only exception is works which |
1882 | * belong to workqueues with a rescuer which will be explained in |
1883 | * rescuer_thread(). |
1884 | */ |
1885 | static int worker_thread(void *__worker) |
1886 | { |
1887 | struct worker *worker = __worker; |
1888 | struct global_cwq *gcwq = worker->gcwq; |
1889 | |
1890 | /* tell the scheduler that this is a workqueue worker */ |
1891 | worker->task->flags |= PF_WQ_WORKER; |
1892 | woke_up: |
1893 | spin_lock_irq(&gcwq->lock); |
1894 | |
1895 | /* DIE can be set only while we're idle, checking here is enough */ |
1896 | if (worker->flags & WORKER_DIE) { |
1897 | spin_unlock_irq(&gcwq->lock); |
1898 | worker->task->flags &= ~PF_WQ_WORKER; |
1899 | return 0; |
1900 | } |
1901 | |
1902 | worker_leave_idle(worker); |
1903 | recheck: |
1904 | /* no more worker necessary? */ |
1905 | if (!need_more_worker(gcwq)) |
1906 | goto sleep; |
1907 | |
1908 | /* do we need to manage? */ |
1909 | if (unlikely(!may_start_working(gcwq)) && manage_workers(worker)) |
1910 | goto recheck; |
1911 | |
1912 | /* |
1913 | * ->scheduled list can only be filled while a worker is |
1914 | * preparing to process a work or actually processing it. |
1915 | * Make sure nobody diddled with it while I was sleeping. |
1916 | */ |
1917 | BUG_ON(!list_empty(&worker->scheduled)); |
1918 | |
1919 | /* |
1920 | * When control reaches this point, we're guaranteed to have |
1921 | * at least one idle worker or that someone else has already |
1922 | * assumed the manager role. |
1923 | */ |
1924 | worker_clr_flags(worker, WORKER_PREP); |
1925 | |
1926 | do { |
1927 | struct work_struct *work = |
1928 | list_first_entry(&gcwq->worklist, |
1929 | struct work_struct, entry); |
1930 | |
1931 | if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { |
1932 | /* optimization path, not strictly necessary */ |
1933 | process_one_work(worker, work); |
1934 | if (unlikely(!list_empty(&worker->scheduled))) |
1935 | process_scheduled_works(worker); |
1936 | } else { |
1937 | move_linked_works(work, &worker->scheduled, NULL); |
1938 | process_scheduled_works(worker); |
1939 | } |
1940 | } while (keep_working(gcwq)); |
1941 | |
1942 | worker_set_flags(worker, WORKER_PREP, false); |
1943 | sleep: |
1944 | if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker)) |
1945 | goto recheck; |
1946 | |
1947 | /* |
1948 | * gcwq->lock is held and there's no work to process and no |
1949 | * need to manage, sleep. Workers are woken up only while |
1950 | * holding gcwq->lock or from local cpu, so setting the |
1951 | * current state before releasing gcwq->lock is enough to |
1952 | * prevent losing any event. |
1953 | */ |
1954 | worker_enter_idle(worker); |
1955 | __set_current_state(TASK_INTERRUPTIBLE); |
1956 | spin_unlock_irq(&gcwq->lock); |
1957 | schedule(); |
1958 | goto woke_up; |
1959 | } |
1960 | |
1961 | /** |
1962 | * rescuer_thread - the rescuer thread function |
1963 | * @__wq: the associated workqueue |
1964 | * |
1965 | * Workqueue rescuer thread function. There's one rescuer for each |
1966 | * workqueue which has WQ_RESCUER set. |
1967 | * |
1968 | * Regular work processing on a gcwq may block trying to create a new |
1969 | * worker which uses GFP_KERNEL allocation which has slight chance of |
1970 | * developing into deadlock if some works currently on the same queue |
1971 | * need to be processed to satisfy the GFP_KERNEL allocation. This is |
1972 | * the problem rescuer solves. |
1973 | * |
1974 | * When such condition is possible, the gcwq summons rescuers of all |
1975 | * workqueues which have works queued on the gcwq and let them process |
1976 | * those works so that forward progress can be guaranteed. |
1977 | * |
1978 | * This should happen rarely. |
1979 | */ |
1980 | static int rescuer_thread(void *__wq) |
1981 | { |
1982 | struct workqueue_struct *wq = __wq; |
1983 | struct worker *rescuer = wq->rescuer; |
1984 | struct list_head *scheduled = &rescuer->scheduled; |
1985 | bool is_unbound = wq->flags & WQ_UNBOUND; |
1986 | unsigned int cpu; |
1987 | |
1988 | set_user_nice(current, RESCUER_NICE_LEVEL); |
1989 | repeat: |
1990 | set_current_state(TASK_INTERRUPTIBLE); |
1991 | |
1992 | if (kthread_should_stop()) |
1993 | return 0; |
1994 | |
1995 | /* |
1996 | * See whether any cpu is asking for help. Unbounded |
1997 | * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. |
1998 | */ |
1999 | for_each_mayday_cpu(cpu, wq->mayday_mask) { |
2000 | unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; |
2001 | struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); |
2002 | struct global_cwq *gcwq = cwq->gcwq; |
2003 | struct work_struct *work, *n; |
2004 | |
2005 | __set_current_state(TASK_RUNNING); |
2006 | mayday_clear_cpu(cpu, wq->mayday_mask); |
2007 | |
2008 | /* migrate to the target cpu if possible */ |
2009 | rescuer->gcwq = gcwq; |
2010 | worker_maybe_bind_and_lock(rescuer); |
2011 | |
2012 | /* |
2013 | * Slurp in all works issued via this workqueue and |
2014 | * process'em. |
2015 | */ |
2016 | BUG_ON(!list_empty(&rescuer->scheduled)); |
2017 | list_for_each_entry_safe(work, n, &gcwq->worklist, entry) |
2018 | if (get_work_cwq(work) == cwq) |
2019 | move_linked_works(work, scheduled, &n); |
2020 | |
2021 | process_scheduled_works(rescuer); |
2022 | spin_unlock_irq(&gcwq->lock); |
2023 | } |
2024 | |
2025 | schedule(); |
2026 | goto repeat; |
2027 | } |
2028 | |
2029 | struct wq_barrier { |
2030 | struct work_struct work; |
2031 | struct completion done; |
2032 | }; |
2033 | |
2034 | static void wq_barrier_func(struct work_struct *work) |
2035 | { |
2036 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); |
2037 | complete(&barr->done); |
2038 | } |
2039 | |
2040 | /** |
2041 | * insert_wq_barrier - insert a barrier work |
2042 | * @cwq: cwq to insert barrier into |
2043 | * @barr: wq_barrier to insert |
2044 | * @target: target work to attach @barr to |
2045 | * @worker: worker currently executing @target, NULL if @target is not executing |
2046 | * |
2047 | * @barr is linked to @target such that @barr is completed only after |
2048 | * @target finishes execution. Please note that the ordering |
2049 | * guarantee is observed only with respect to @target and on the local |
2050 | * cpu. |
2051 | * |
2052 | * Currently, a queued barrier can't be canceled. This is because |
2053 | * try_to_grab_pending() can't determine whether the work to be |
2054 | * grabbed is at the head of the queue and thus can't clear LINKED |
2055 | * flag of the previous work while there must be a valid next work |
2056 | * after a work with LINKED flag set. |
2057 | * |
2058 | * Note that when @worker is non-NULL, @target may be modified |
2059 | * underneath us, so we can't reliably determine cwq from @target. |
2060 | * |
2061 | * CONTEXT: |
2062 | * spin_lock_irq(gcwq->lock). |
2063 | */ |
2064 | static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, |
2065 | struct wq_barrier *barr, |
2066 | struct work_struct *target, struct worker *worker) |
2067 | { |
2068 | struct list_head *head; |
2069 | unsigned int linked = 0; |
2070 | |
2071 | /* |
2072 | * debugobject calls are safe here even with gcwq->lock locked |
2073 | * as we know for sure that this will not trigger any of the |
2074 | * checks and call back into the fixup functions where we |
2075 | * might deadlock. |
2076 | */ |
2077 | INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); |
2078 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
2079 | init_completion(&barr->done); |
2080 | |
2081 | /* |
2082 | * If @target is currently being executed, schedule the |
2083 | * barrier to the worker; otherwise, put it after @target. |
2084 | */ |
2085 | if (worker) |
2086 | head = worker->scheduled.next; |
2087 | else { |
2088 | unsigned long *bits = work_data_bits(target); |
2089 | |
2090 | head = target->entry.next; |
2091 | /* there can already be other linked works, inherit and set */ |
2092 | linked = *bits & WORK_STRUCT_LINKED; |
2093 | __set_bit(WORK_STRUCT_LINKED_BIT, bits); |
2094 | } |
2095 | |
2096 | debug_work_activate(&barr->work); |
2097 | insert_work(cwq, &barr->work, head, |
2098 | work_color_to_flags(WORK_NO_COLOR) | linked); |
2099 | } |
2100 | |
2101 | /** |
2102 | * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing |
2103 | * @wq: workqueue being flushed |
2104 | * @flush_color: new flush color, < 0 for no-op |
2105 | * @work_color: new work color, < 0 for no-op |
2106 | * |
2107 | * Prepare cwqs for workqueue flushing. |
2108 | * |
2109 | * If @flush_color is non-negative, flush_color on all cwqs should be |
2110 | * -1. If no cwq has in-flight commands at the specified color, all |
2111 | * cwq->flush_color's stay at -1 and %false is returned. If any cwq |
2112 | * has in flight commands, its cwq->flush_color is set to |
2113 | * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq |
2114 | * wakeup logic is armed and %true is returned. |
2115 | * |
2116 | * The caller should have initialized @wq->first_flusher prior to |
2117 | * calling this function with non-negative @flush_color. If |
2118 | * @flush_color is negative, no flush color update is done and %false |
2119 | * is returned. |
2120 | * |
2121 | * If @work_color is non-negative, all cwqs should have the same |
2122 | * work_color which is previous to @work_color and all will be |
2123 | * advanced to @work_color. |
2124 | * |
2125 | * CONTEXT: |
2126 | * mutex_lock(wq->flush_mutex). |
2127 | * |
2128 | * RETURNS: |
2129 | * %true if @flush_color >= 0 and there's something to flush. %false |
2130 | * otherwise. |
2131 | */ |
2132 | static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, |
2133 | int flush_color, int work_color) |
2134 | { |
2135 | bool wait = false; |
2136 | unsigned int cpu; |
2137 | |
2138 | if (flush_color >= 0) { |
2139 | BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); |
2140 | atomic_set(&wq->nr_cwqs_to_flush, 1); |
2141 | } |
2142 | |
2143 | for_each_cwq_cpu(cpu, wq) { |
2144 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
2145 | struct global_cwq *gcwq = cwq->gcwq; |
2146 | |
2147 | spin_lock_irq(&gcwq->lock); |
2148 | |
2149 | if (flush_color >= 0) { |
2150 | BUG_ON(cwq->flush_color != -1); |
2151 | |
2152 | if (cwq->nr_in_flight[flush_color]) { |
2153 | cwq->flush_color = flush_color; |
2154 | atomic_inc(&wq->nr_cwqs_to_flush); |
2155 | wait = true; |
2156 | } |
2157 | } |
2158 | |
2159 | if (work_color >= 0) { |
2160 | BUG_ON(work_color != work_next_color(cwq->work_color)); |
2161 | cwq->work_color = work_color; |
2162 | } |
2163 | |
2164 | spin_unlock_irq(&gcwq->lock); |
2165 | } |
2166 | |
2167 | if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) |
2168 | complete(&wq->first_flusher->done); |
2169 | |
2170 | return wait; |
2171 | } |
2172 | |
2173 | /** |
2174 | * flush_workqueue - ensure that any scheduled work has run to completion. |
2175 | * @wq: workqueue to flush |
2176 | * |
2177 | * Forces execution of the workqueue and blocks until its completion. |
2178 | * This is typically used in driver shutdown handlers. |
2179 | * |
2180 | * We sleep until all works which were queued on entry have been handled, |
2181 | * but we are not livelocked by new incoming ones. |
2182 | */ |
2183 | void flush_workqueue(struct workqueue_struct *wq) |
2184 | { |
2185 | struct wq_flusher this_flusher = { |
2186 | .list = LIST_HEAD_INIT(this_flusher.list), |
2187 | .flush_color = -1, |
2188 | .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), |
2189 | }; |
2190 | int next_color; |
2191 | |
2192 | lock_map_acquire(&wq->lockdep_map); |
2193 | lock_map_release(&wq->lockdep_map); |
2194 | |
2195 | mutex_lock(&wq->flush_mutex); |
2196 | |
2197 | /* |
2198 | * Start-to-wait phase |
2199 | */ |
2200 | next_color = work_next_color(wq->work_color); |
2201 | |
2202 | if (next_color != wq->flush_color) { |
2203 | /* |
2204 | * Color space is not full. The current work_color |
2205 | * becomes our flush_color and work_color is advanced |
2206 | * by one. |
2207 | */ |
2208 | BUG_ON(!list_empty(&wq->flusher_overflow)); |
2209 | this_flusher.flush_color = wq->work_color; |
2210 | wq->work_color = next_color; |
2211 | |
2212 | if (!wq->first_flusher) { |
2213 | /* no flush in progress, become the first flusher */ |
2214 | BUG_ON(wq->flush_color != this_flusher.flush_color); |
2215 | |
2216 | wq->first_flusher = &this_flusher; |
2217 | |
2218 | if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, |
2219 | wq->work_color)) { |
2220 | /* nothing to flush, done */ |
2221 | wq->flush_color = next_color; |
2222 | wq->first_flusher = NULL; |
2223 | goto out_unlock; |
2224 | } |
2225 | } else { |
2226 | /* wait in queue */ |
2227 | BUG_ON(wq->flush_color == this_flusher.flush_color); |
2228 | list_add_tail(&this_flusher.list, &wq->flusher_queue); |
2229 | flush_workqueue_prep_cwqs(wq, -1, wq->work_color); |
2230 | } |
2231 | } else { |
2232 | /* |
2233 | * Oops, color space is full, wait on overflow queue. |
2234 | * The next flush completion will assign us |
2235 | * flush_color and transfer to flusher_queue. |
2236 | */ |
2237 | list_add_tail(&this_flusher.list, &wq->flusher_overflow); |
2238 | } |
2239 | |
2240 | mutex_unlock(&wq->flush_mutex); |
2241 | |
2242 | wait_for_completion(&this_flusher.done); |
2243 | |
2244 | /* |
2245 | * Wake-up-and-cascade phase |
2246 | * |
2247 | * First flushers are responsible for cascading flushes and |
2248 | * handling overflow. Non-first flushers can simply return. |
2249 | */ |
2250 | if (wq->first_flusher != &this_flusher) |
2251 | return; |
2252 | |
2253 | mutex_lock(&wq->flush_mutex); |
2254 | |
2255 | /* we might have raced, check again with mutex held */ |
2256 | if (wq->first_flusher != &this_flusher) |
2257 | goto out_unlock; |
2258 | |
2259 | wq->first_flusher = NULL; |
2260 | |
2261 | BUG_ON(!list_empty(&this_flusher.list)); |
2262 | BUG_ON(wq->flush_color != this_flusher.flush_color); |
2263 | |
2264 | while (true) { |
2265 | struct wq_flusher *next, *tmp; |
2266 | |
2267 | /* complete all the flushers sharing the current flush color */ |
2268 | list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { |
2269 | if (next->flush_color != wq->flush_color) |
2270 | break; |
2271 | list_del_init(&next->list); |
2272 | complete(&next->done); |
2273 | } |
2274 | |
2275 | BUG_ON(!list_empty(&wq->flusher_overflow) && |
2276 | wq->flush_color != work_next_color(wq->work_color)); |
2277 | |
2278 | /* this flush_color is finished, advance by one */ |
2279 | wq->flush_color = work_next_color(wq->flush_color); |
2280 | |
2281 | /* one color has been freed, handle overflow queue */ |
2282 | if (!list_empty(&wq->flusher_overflow)) { |
2283 | /* |
2284 | * Assign the same color to all overflowed |
2285 | * flushers, advance work_color and append to |
2286 | * flusher_queue. This is the start-to-wait |
2287 | * phase for these overflowed flushers. |
2288 | */ |
2289 | list_for_each_entry(tmp, &wq->flusher_overflow, list) |
2290 | tmp->flush_color = wq->work_color; |
2291 | |
2292 | wq->work_color = work_next_color(wq->work_color); |
2293 | |
2294 | list_splice_tail_init(&wq->flusher_overflow, |
2295 | &wq->flusher_queue); |
2296 | flush_workqueue_prep_cwqs(wq, -1, wq->work_color); |
2297 | } |
2298 | |
2299 | if (list_empty(&wq->flusher_queue)) { |
2300 | BUG_ON(wq->flush_color != wq->work_color); |
2301 | break; |
2302 | } |
2303 | |
2304 | /* |
2305 | * Need to flush more colors. Make the next flusher |
2306 | * the new first flusher and arm cwqs. |
2307 | */ |
2308 | BUG_ON(wq->flush_color == wq->work_color); |
2309 | BUG_ON(wq->flush_color != next->flush_color); |
2310 | |
2311 | list_del_init(&next->list); |
2312 | wq->first_flusher = next; |
2313 | |
2314 | if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) |
2315 | break; |
2316 | |
2317 | /* |
2318 | * Meh... this color is already done, clear first |
2319 | * flusher and repeat cascading. |
2320 | */ |
2321 | wq->first_flusher = NULL; |
2322 | } |
2323 | |
2324 | out_unlock: |
2325 | mutex_unlock(&wq->flush_mutex); |
2326 | } |
2327 | EXPORT_SYMBOL_GPL(flush_workqueue); |
2328 | |
2329 | /** |
2330 | * flush_work - block until a work_struct's callback has terminated |
2331 | * @work: the work which is to be flushed |
2332 | * |
2333 | * Returns false if @work has already terminated. |
2334 | * |
2335 | * It is expected that, prior to calling flush_work(), the caller has |
2336 | * arranged for the work to not be requeued, otherwise it doesn't make |
2337 | * sense to use this function. |
2338 | */ |
2339 | int flush_work(struct work_struct *work) |
2340 | { |
2341 | struct worker *worker = NULL; |
2342 | struct global_cwq *gcwq; |
2343 | struct cpu_workqueue_struct *cwq; |
2344 | struct wq_barrier barr; |
2345 | |
2346 | might_sleep(); |
2347 | gcwq = get_work_gcwq(work); |
2348 | if (!gcwq) |
2349 | return 0; |
2350 | |
2351 | spin_lock_irq(&gcwq->lock); |
2352 | if (!list_empty(&work->entry)) { |
2353 | /* |
2354 | * See the comment near try_to_grab_pending()->smp_rmb(). |
2355 | * If it was re-queued to a different gcwq under us, we |
2356 | * are not going to wait. |
2357 | */ |
2358 | smp_rmb(); |
2359 | cwq = get_work_cwq(work); |
2360 | if (unlikely(!cwq || gcwq != cwq->gcwq)) |
2361 | goto already_gone; |
2362 | } else { |
2363 | worker = find_worker_executing_work(gcwq, work); |
2364 | if (!worker) |
2365 | goto already_gone; |
2366 | cwq = worker->current_cwq; |
2367 | } |
2368 | |
2369 | insert_wq_barrier(cwq, &barr, work, worker); |
2370 | spin_unlock_irq(&gcwq->lock); |
2371 | |
2372 | lock_map_acquire(&cwq->wq->lockdep_map); |
2373 | lock_map_release(&cwq->wq->lockdep_map); |
2374 | |
2375 | wait_for_completion(&barr.done); |
2376 | destroy_work_on_stack(&barr.work); |
2377 | return 1; |
2378 | already_gone: |
2379 | spin_unlock_irq(&gcwq->lock); |
2380 | return 0; |
2381 | } |
2382 | EXPORT_SYMBOL_GPL(flush_work); |
2383 | |
2384 | /* |
2385 | * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, |
2386 | * so this work can't be re-armed in any way. |
2387 | */ |
2388 | static int try_to_grab_pending(struct work_struct *work) |
2389 | { |
2390 | struct global_cwq *gcwq; |
2391 | int ret = -1; |
2392 | |
2393 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
2394 | return 0; |
2395 | |
2396 | /* |
2397 | * The queueing is in progress, or it is already queued. Try to |
2398 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. |
2399 | */ |
2400 | gcwq = get_work_gcwq(work); |
2401 | if (!gcwq) |
2402 | return ret; |
2403 | |
2404 | spin_lock_irq(&gcwq->lock); |
2405 | if (!list_empty(&work->entry)) { |
2406 | /* |
2407 | * This work is queued, but perhaps we locked the wrong gcwq. |
2408 | * In that case we must see the new value after rmb(), see |
2409 | * insert_work()->wmb(). |
2410 | */ |
2411 | smp_rmb(); |
2412 | if (gcwq == get_work_gcwq(work)) { |
2413 | debug_work_deactivate(work); |
2414 | list_del_init(&work->entry); |
2415 | cwq_dec_nr_in_flight(get_work_cwq(work), |
2416 | get_work_color(work), |
2417 | *work_data_bits(work) & WORK_STRUCT_DELAYED); |
2418 | ret = 1; |
2419 | } |
2420 | } |
2421 | spin_unlock_irq(&gcwq->lock); |
2422 | |
2423 | return ret; |
2424 | } |
2425 | |
2426 | static void wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) |
2427 | { |
2428 | struct wq_barrier barr; |
2429 | struct worker *worker; |
2430 | |
2431 | spin_lock_irq(&gcwq->lock); |
2432 | |
2433 | worker = find_worker_executing_work(gcwq, work); |
2434 | if (unlikely(worker)) |
2435 | insert_wq_barrier(worker->current_cwq, &barr, work, worker); |
2436 | |
2437 | spin_unlock_irq(&gcwq->lock); |
2438 | |
2439 | if (unlikely(worker)) { |
2440 | wait_for_completion(&barr.done); |
2441 | destroy_work_on_stack(&barr.work); |
2442 | } |
2443 | } |
2444 | |
2445 | static void wait_on_work(struct work_struct *work) |
2446 | { |
2447 | int cpu; |
2448 | |
2449 | might_sleep(); |
2450 | |
2451 | lock_map_acquire(&work->lockdep_map); |
2452 | lock_map_release(&work->lockdep_map); |
2453 | |
2454 | for_each_gcwq_cpu(cpu) |
2455 | wait_on_cpu_work(get_gcwq(cpu), work); |
2456 | } |
2457 | |
2458 | static int __cancel_work_timer(struct work_struct *work, |
2459 | struct timer_list* timer) |
2460 | { |
2461 | int ret; |
2462 | |
2463 | do { |
2464 | ret = (timer && likely(del_timer(timer))); |
2465 | if (!ret) |
2466 | ret = try_to_grab_pending(work); |
2467 | wait_on_work(work); |
2468 | } while (unlikely(ret < 0)); |
2469 | |
2470 | clear_work_data(work); |
2471 | return ret; |
2472 | } |
2473 | |
2474 | /** |
2475 | * cancel_work_sync - block until a work_struct's callback has terminated |
2476 | * @work: the work which is to be flushed |
2477 | * |
2478 | * Returns true if @work was pending. |
2479 | * |
2480 | * cancel_work_sync() will cancel the work if it is queued. If the work's |
2481 | * callback appears to be running, cancel_work_sync() will block until it |
2482 | * has completed. |
2483 | * |
2484 | * It is possible to use this function if the work re-queues itself. It can |
2485 | * cancel the work even if it migrates to another workqueue, however in that |
2486 | * case it only guarantees that work->func() has completed on the last queued |
2487 | * workqueue. |
2488 | * |
2489 | * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not |
2490 | * pending, otherwise it goes into a busy-wait loop until the timer expires. |
2491 | * |
2492 | * The caller must ensure that workqueue_struct on which this work was last |
2493 | * queued can't be destroyed before this function returns. |
2494 | */ |
2495 | int cancel_work_sync(struct work_struct *work) |
2496 | { |
2497 | return __cancel_work_timer(work, NULL); |
2498 | } |
2499 | EXPORT_SYMBOL_GPL(cancel_work_sync); |
2500 | |
2501 | /** |
2502 | * cancel_delayed_work_sync - reliably kill off a delayed work. |
2503 | * @dwork: the delayed work struct |
2504 | * |
2505 | * Returns true if @dwork was pending. |
2506 | * |
2507 | * It is possible to use this function if @dwork rearms itself via queue_work() |
2508 | * or queue_delayed_work(). See also the comment for cancel_work_sync(). |
2509 | */ |
2510 | int cancel_delayed_work_sync(struct delayed_work *dwork) |
2511 | { |
2512 | return __cancel_work_timer(&dwork->work, &dwork->timer); |
2513 | } |
2514 | EXPORT_SYMBOL(cancel_delayed_work_sync); |
2515 | |
2516 | /** |
2517 | * schedule_work - put work task in global workqueue |
2518 | * @work: job to be done |
2519 | * |
2520 | * Returns zero if @work was already on the kernel-global workqueue and |
2521 | * non-zero otherwise. |
2522 | * |
2523 | * This puts a job in the kernel-global workqueue if it was not already |
2524 | * queued and leaves it in the same position on the kernel-global |
2525 | * workqueue otherwise. |
2526 | */ |
2527 | int schedule_work(struct work_struct *work) |
2528 | { |
2529 | return queue_work(system_wq, work); |
2530 | } |
2531 | EXPORT_SYMBOL(schedule_work); |
2532 | |
2533 | /* |
2534 | * schedule_work_on - put work task on a specific cpu |
2535 | * @cpu: cpu to put the work task on |
2536 | * @work: job to be done |
2537 | * |
2538 | * This puts a job on a specific cpu |
2539 | */ |
2540 | int schedule_work_on(int cpu, struct work_struct *work) |
2541 | { |
2542 | return queue_work_on(cpu, system_wq, work); |
2543 | } |
2544 | EXPORT_SYMBOL(schedule_work_on); |
2545 | |
2546 | /** |
2547 | * schedule_delayed_work - put work task in global workqueue after delay |
2548 | * @dwork: job to be done |
2549 | * @delay: number of jiffies to wait or 0 for immediate execution |
2550 | * |
2551 | * After waiting for a given time this puts a job in the kernel-global |
2552 | * workqueue. |
2553 | */ |
2554 | int schedule_delayed_work(struct delayed_work *dwork, |
2555 | unsigned long delay) |
2556 | { |
2557 | return queue_delayed_work(system_wq, dwork, delay); |
2558 | } |
2559 | EXPORT_SYMBOL(schedule_delayed_work); |
2560 | |
2561 | /** |
2562 | * flush_delayed_work - block until a dwork_struct's callback has terminated |
2563 | * @dwork: the delayed work which is to be flushed |
2564 | * |
2565 | * Any timeout is cancelled, and any pending work is run immediately. |
2566 | */ |
2567 | void flush_delayed_work(struct delayed_work *dwork) |
2568 | { |
2569 | if (del_timer_sync(&dwork->timer)) { |
2570 | __queue_work(get_cpu(), get_work_cwq(&dwork->work)->wq, |
2571 | &dwork->work); |
2572 | put_cpu(); |
2573 | } |
2574 | flush_work(&dwork->work); |
2575 | } |
2576 | EXPORT_SYMBOL(flush_delayed_work); |
2577 | |
2578 | /** |
2579 | * schedule_delayed_work_on - queue work in global workqueue on CPU after delay |
2580 | * @cpu: cpu to use |
2581 | * @dwork: job to be done |
2582 | * @delay: number of jiffies to wait |
2583 | * |
2584 | * After waiting for a given time this puts a job in the kernel-global |
2585 | * workqueue on the specified CPU. |
2586 | */ |
2587 | int schedule_delayed_work_on(int cpu, |
2588 | struct delayed_work *dwork, unsigned long delay) |
2589 | { |
2590 | return queue_delayed_work_on(cpu, system_wq, dwork, delay); |
2591 | } |
2592 | EXPORT_SYMBOL(schedule_delayed_work_on); |
2593 | |
2594 | /** |
2595 | * schedule_on_each_cpu - call a function on each online CPU from keventd |
2596 | * @func: the function to call |
2597 | * |
2598 | * Returns zero on success. |
2599 | * Returns -ve errno on failure. |
2600 | * |
2601 | * schedule_on_each_cpu() is very slow. |
2602 | */ |
2603 | int schedule_on_each_cpu(work_func_t func) |
2604 | { |
2605 | int cpu; |
2606 | struct work_struct __percpu *works; |
2607 | |
2608 | works = alloc_percpu(struct work_struct); |
2609 | if (!works) |
2610 | return -ENOMEM; |
2611 | |
2612 | get_online_cpus(); |
2613 | |
2614 | for_each_online_cpu(cpu) { |
2615 | struct work_struct *work = per_cpu_ptr(works, cpu); |
2616 | |
2617 | INIT_WORK(work, func); |
2618 | schedule_work_on(cpu, work); |
2619 | } |
2620 | |
2621 | for_each_online_cpu(cpu) |
2622 | flush_work(per_cpu_ptr(works, cpu)); |
2623 | |
2624 | put_online_cpus(); |
2625 | free_percpu(works); |
2626 | return 0; |
2627 | } |
2628 | |
2629 | /** |
2630 | * flush_scheduled_work - ensure that any scheduled work has run to completion. |
2631 | * |
2632 | * Forces execution of the kernel-global workqueue and blocks until its |
2633 | * completion. |
2634 | * |
2635 | * Think twice before calling this function! It's very easy to get into |
2636 | * trouble if you don't take great care. Either of the following situations |
2637 | * will lead to deadlock: |
2638 | * |
2639 | * One of the work items currently on the workqueue needs to acquire |
2640 | * a lock held by your code or its caller. |
2641 | * |
2642 | * Your code is running in the context of a work routine. |
2643 | * |
2644 | * They will be detected by lockdep when they occur, but the first might not |
2645 | * occur very often. It depends on what work items are on the workqueue and |
2646 | * what locks they need, which you have no control over. |
2647 | * |
2648 | * In most situations flushing the entire workqueue is overkill; you merely |
2649 | * need to know that a particular work item isn't queued and isn't running. |
2650 | * In such cases you should use cancel_delayed_work_sync() or |
2651 | * cancel_work_sync() instead. |
2652 | */ |
2653 | void flush_scheduled_work(void) |
2654 | { |
2655 | flush_workqueue(system_wq); |
2656 | } |
2657 | EXPORT_SYMBOL(flush_scheduled_work); |
2658 | |
2659 | /** |
2660 | * execute_in_process_context - reliably execute the routine with user context |
2661 | * @fn: the function to execute |
2662 | * @ew: guaranteed storage for the execute work structure (must |
2663 | * be available when the work executes) |
2664 | * |
2665 | * Executes the function immediately if process context is available, |
2666 | * otherwise schedules the function for delayed execution. |
2667 | * |
2668 | * Returns: 0 - function was executed |
2669 | * 1 - function was scheduled for execution |
2670 | */ |
2671 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
2672 | { |
2673 | if (!in_interrupt()) { |
2674 | fn(&ew->work); |
2675 | return 0; |
2676 | } |
2677 | |
2678 | INIT_WORK(&ew->work, fn); |
2679 | schedule_work(&ew->work); |
2680 | |
2681 | return 1; |
2682 | } |
2683 | EXPORT_SYMBOL_GPL(execute_in_process_context); |
2684 | |
2685 | int keventd_up(void) |
2686 | { |
2687 | return system_wq != NULL; |
2688 | } |
2689 | |
2690 | static int alloc_cwqs(struct workqueue_struct *wq) |
2691 | { |
2692 | /* |
2693 | * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. |
2694 | * Make sure that the alignment isn't lower than that of |
2695 | * unsigned long long. |
2696 | */ |
2697 | const size_t size = sizeof(struct cpu_workqueue_struct); |
2698 | const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, |
2699 | __alignof__(unsigned long long)); |
2700 | #ifdef CONFIG_SMP |
2701 | bool percpu = !(wq->flags & WQ_UNBOUND); |
2702 | #else |
2703 | bool percpu = false; |
2704 | #endif |
2705 | |
2706 | if (percpu) |
2707 | wq->cpu_wq.pcpu = __alloc_percpu(size, align); |
2708 | else { |
2709 | void *ptr; |
2710 | |
2711 | /* |
2712 | * Allocate enough room to align cwq and put an extra |
2713 | * pointer at the end pointing back to the originally |
2714 | * allocated pointer which will be used for free. |
2715 | */ |
2716 | ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); |
2717 | if (ptr) { |
2718 | wq->cpu_wq.single = PTR_ALIGN(ptr, align); |
2719 | *(void **)(wq->cpu_wq.single + 1) = ptr; |
2720 | } |
2721 | } |
2722 | |
2723 | /* just in case, make sure it's actually aligned */ |
2724 | BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); |
2725 | return wq->cpu_wq.v ? 0 : -ENOMEM; |
2726 | } |
2727 | |
2728 | static void free_cwqs(struct workqueue_struct *wq) |
2729 | { |
2730 | #ifdef CONFIG_SMP |
2731 | bool percpu = !(wq->flags & WQ_UNBOUND); |
2732 | #else |
2733 | bool percpu = false; |
2734 | #endif |
2735 | |
2736 | if (percpu) |
2737 | free_percpu(wq->cpu_wq.pcpu); |
2738 | else if (wq->cpu_wq.single) { |
2739 | /* the pointer to free is stored right after the cwq */ |
2740 | kfree(*(void **)(wq->cpu_wq.single + 1)); |
2741 | } |
2742 | } |
2743 | |
2744 | static int wq_clamp_max_active(int max_active, unsigned int flags, |
2745 | const char *name) |
2746 | { |
2747 | int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; |
2748 | |
2749 | if (max_active < 1 || max_active > lim) |
2750 | printk(KERN_WARNING "workqueue: max_active %d requested for %s " |
2751 | "is out of range, clamping between %d and %d\n", |
2752 | max_active, name, 1, lim); |
2753 | |
2754 | return clamp_val(max_active, 1, lim); |
2755 | } |
2756 | |
2757 | struct workqueue_struct *__alloc_workqueue_key(const char *name, |
2758 | unsigned int flags, |
2759 | int max_active, |
2760 | struct lock_class_key *key, |
2761 | const char *lock_name) |
2762 | { |
2763 | struct workqueue_struct *wq; |
2764 | unsigned int cpu; |
2765 | |
2766 | /* |
2767 | * Unbound workqueues aren't concurrency managed and should be |
2768 | * dispatched to workers immediately. |
2769 | */ |
2770 | if (flags & WQ_UNBOUND) |
2771 | flags |= WQ_HIGHPRI; |
2772 | |
2773 | max_active = max_active ?: WQ_DFL_ACTIVE; |
2774 | max_active = wq_clamp_max_active(max_active, flags, name); |
2775 | |
2776 | wq = kzalloc(sizeof(*wq), GFP_KERNEL); |
2777 | if (!wq) |
2778 | goto err; |
2779 | |
2780 | wq->flags = flags; |
2781 | wq->saved_max_active = max_active; |
2782 | mutex_init(&wq->flush_mutex); |
2783 | atomic_set(&wq->nr_cwqs_to_flush, 0); |
2784 | INIT_LIST_HEAD(&wq->flusher_queue); |
2785 | INIT_LIST_HEAD(&wq->flusher_overflow); |
2786 | |
2787 | wq->name = name; |
2788 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
2789 | INIT_LIST_HEAD(&wq->list); |
2790 | |
2791 | if (alloc_cwqs(wq) < 0) |
2792 | goto err; |
2793 | |
2794 | for_each_cwq_cpu(cpu, wq) { |
2795 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
2796 | struct global_cwq *gcwq = get_gcwq(cpu); |
2797 | |
2798 | BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); |
2799 | cwq->gcwq = gcwq; |
2800 | cwq->wq = wq; |
2801 | cwq->flush_color = -1; |
2802 | cwq->max_active = max_active; |
2803 | INIT_LIST_HEAD(&cwq->delayed_works); |
2804 | } |
2805 | |
2806 | if (flags & WQ_RESCUER) { |
2807 | struct worker *rescuer; |
2808 | |
2809 | if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) |
2810 | goto err; |
2811 | |
2812 | wq->rescuer = rescuer = alloc_worker(); |
2813 | if (!rescuer) |
2814 | goto err; |
2815 | |
2816 | rescuer->task = kthread_create(rescuer_thread, wq, "%s", name); |
2817 | if (IS_ERR(rescuer->task)) |
2818 | goto err; |
2819 | |
2820 | rescuer->task->flags |= PF_THREAD_BOUND; |
2821 | wake_up_process(rescuer->task); |
2822 | } |
2823 | |
2824 | /* |
2825 | * workqueue_lock protects global freeze state and workqueues |
2826 | * list. Grab it, set max_active accordingly and add the new |
2827 | * workqueue to workqueues list. |
2828 | */ |
2829 | spin_lock(&workqueue_lock); |
2830 | |
2831 | if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) |
2832 | for_each_cwq_cpu(cpu, wq) |
2833 | get_cwq(cpu, wq)->max_active = 0; |
2834 | |
2835 | list_add(&wq->list, &workqueues); |
2836 | |
2837 | spin_unlock(&workqueue_lock); |
2838 | |
2839 | return wq; |
2840 | err: |
2841 | if (wq) { |
2842 | free_cwqs(wq); |
2843 | free_mayday_mask(wq->mayday_mask); |
2844 | kfree(wq->rescuer); |
2845 | kfree(wq); |
2846 | } |
2847 | return NULL; |
2848 | } |
2849 | EXPORT_SYMBOL_GPL(__alloc_workqueue_key); |
2850 | |
2851 | /** |
2852 | * destroy_workqueue - safely terminate a workqueue |
2853 | * @wq: target workqueue |
2854 | * |
2855 | * Safely destroy a workqueue. All work currently pending will be done first. |
2856 | */ |
2857 | void destroy_workqueue(struct workqueue_struct *wq) |
2858 | { |
2859 | unsigned int cpu; |
2860 | |
2861 | wq->flags |= WQ_DYING; |
2862 | flush_workqueue(wq); |
2863 | |
2864 | /* |
2865 | * wq list is used to freeze wq, remove from list after |
2866 | * flushing is complete in case freeze races us. |
2867 | */ |
2868 | spin_lock(&workqueue_lock); |
2869 | list_del(&wq->list); |
2870 | spin_unlock(&workqueue_lock); |
2871 | |
2872 | /* sanity check */ |
2873 | for_each_cwq_cpu(cpu, wq) { |
2874 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
2875 | int i; |
2876 | |
2877 | for (i = 0; i < WORK_NR_COLORS; i++) |
2878 | BUG_ON(cwq->nr_in_flight[i]); |
2879 | BUG_ON(cwq->nr_active); |
2880 | BUG_ON(!list_empty(&cwq->delayed_works)); |
2881 | } |
2882 | |
2883 | if (wq->flags & WQ_RESCUER) { |
2884 | kthread_stop(wq->rescuer->task); |
2885 | free_mayday_mask(wq->mayday_mask); |
2886 | kfree(wq->rescuer); |
2887 | } |
2888 | |
2889 | free_cwqs(wq); |
2890 | kfree(wq); |
2891 | } |
2892 | EXPORT_SYMBOL_GPL(destroy_workqueue); |
2893 | |
2894 | /** |
2895 | * workqueue_set_max_active - adjust max_active of a workqueue |
2896 | * @wq: target workqueue |
2897 | * @max_active: new max_active value. |
2898 | * |
2899 | * Set max_active of @wq to @max_active. |
2900 | * |
2901 | * CONTEXT: |
2902 | * Don't call from IRQ context. |
2903 | */ |
2904 | void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) |
2905 | { |
2906 | unsigned int cpu; |
2907 | |
2908 | max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); |
2909 | |
2910 | spin_lock(&workqueue_lock); |
2911 | |
2912 | wq->saved_max_active = max_active; |
2913 | |
2914 | for_each_cwq_cpu(cpu, wq) { |
2915 | struct global_cwq *gcwq = get_gcwq(cpu); |
2916 | |
2917 | spin_lock_irq(&gcwq->lock); |
2918 | |
2919 | if (!(wq->flags & WQ_FREEZEABLE) || |
2920 | !(gcwq->flags & GCWQ_FREEZING)) |
2921 | get_cwq(gcwq->cpu, wq)->max_active = max_active; |
2922 | |
2923 | spin_unlock_irq(&gcwq->lock); |
2924 | } |
2925 | |
2926 | spin_unlock(&workqueue_lock); |
2927 | } |
2928 | EXPORT_SYMBOL_GPL(workqueue_set_max_active); |
2929 | |
2930 | /** |
2931 | * workqueue_congested - test whether a workqueue is congested |
2932 | * @cpu: CPU in question |
2933 | * @wq: target workqueue |
2934 | * |
2935 | * Test whether @wq's cpu workqueue for @cpu is congested. There is |
2936 | * no synchronization around this function and the test result is |
2937 | * unreliable and only useful as advisory hints or for debugging. |
2938 | * |
2939 | * RETURNS: |
2940 | * %true if congested, %false otherwise. |
2941 | */ |
2942 | bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) |
2943 | { |
2944 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
2945 | |
2946 | return !list_empty(&cwq->delayed_works); |
2947 | } |
2948 | EXPORT_SYMBOL_GPL(workqueue_congested); |
2949 | |
2950 | /** |
2951 | * work_cpu - return the last known associated cpu for @work |
2952 | * @work: the work of interest |
2953 | * |
2954 | * RETURNS: |
2955 | * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. |
2956 | */ |
2957 | unsigned int work_cpu(struct work_struct *work) |
2958 | { |
2959 | struct global_cwq *gcwq = get_work_gcwq(work); |
2960 | |
2961 | return gcwq ? gcwq->cpu : WORK_CPU_NONE; |
2962 | } |
2963 | EXPORT_SYMBOL_GPL(work_cpu); |
2964 | |
2965 | /** |
2966 | * work_busy - test whether a work is currently pending or running |
2967 | * @work: the work to be tested |
2968 | * |
2969 | * Test whether @work is currently pending or running. There is no |
2970 | * synchronization around this function and the test result is |
2971 | * unreliable and only useful as advisory hints or for debugging. |
2972 | * Especially for reentrant wqs, the pending state might hide the |
2973 | * running state. |
2974 | * |
2975 | * RETURNS: |
2976 | * OR'd bitmask of WORK_BUSY_* bits. |
2977 | */ |
2978 | unsigned int work_busy(struct work_struct *work) |
2979 | { |
2980 | struct global_cwq *gcwq = get_work_gcwq(work); |
2981 | unsigned long flags; |
2982 | unsigned int ret = 0; |
2983 | |
2984 | if (!gcwq) |
2985 | return false; |
2986 | |
2987 | spin_lock_irqsave(&gcwq->lock, flags); |
2988 | |
2989 | if (work_pending(work)) |
2990 | ret |= WORK_BUSY_PENDING; |
2991 | if (find_worker_executing_work(gcwq, work)) |
2992 | ret |= WORK_BUSY_RUNNING; |
2993 | |
2994 | spin_unlock_irqrestore(&gcwq->lock, flags); |
2995 | |
2996 | return ret; |
2997 | } |
2998 | EXPORT_SYMBOL_GPL(work_busy); |
2999 | |
3000 | /* |
3001 | * CPU hotplug. |
3002 | * |
3003 | * There are two challenges in supporting CPU hotplug. Firstly, there |
3004 | * are a lot of assumptions on strong associations among work, cwq and |
3005 | * gcwq which make migrating pending and scheduled works very |
3006 | * difficult to implement without impacting hot paths. Secondly, |
3007 | * gcwqs serve mix of short, long and very long running works making |
3008 | * blocked draining impractical. |
3009 | * |
3010 | * This is solved by allowing a gcwq to be detached from CPU, running |
3011 | * it with unbound (rogue) workers and allowing it to be reattached |
3012 | * later if the cpu comes back online. A separate thread is created |
3013 | * to govern a gcwq in such state and is called the trustee of the |
3014 | * gcwq. |
3015 | * |
3016 | * Trustee states and their descriptions. |
3017 | * |
3018 | * START Command state used on startup. On CPU_DOWN_PREPARE, a |
3019 | * new trustee is started with this state. |
3020 | * |
3021 | * IN_CHARGE Once started, trustee will enter this state after |
3022 | * assuming the manager role and making all existing |
3023 | * workers rogue. DOWN_PREPARE waits for trustee to |
3024 | * enter this state. After reaching IN_CHARGE, trustee |
3025 | * tries to execute the pending worklist until it's empty |
3026 | * and the state is set to BUTCHER, or the state is set |
3027 | * to RELEASE. |
3028 | * |
3029 | * BUTCHER Command state which is set by the cpu callback after |
3030 | * the cpu has went down. Once this state is set trustee |
3031 | * knows that there will be no new works on the worklist |
3032 | * and once the worklist is empty it can proceed to |
3033 | * killing idle workers. |
3034 | * |
3035 | * RELEASE Command state which is set by the cpu callback if the |
3036 | * cpu down has been canceled or it has come online |
3037 | * again. After recognizing this state, trustee stops |
3038 | * trying to drain or butcher and clears ROGUE, rebinds |
3039 | * all remaining workers back to the cpu and releases |
3040 | * manager role. |
3041 | * |
3042 | * DONE Trustee will enter this state after BUTCHER or RELEASE |
3043 | * is complete. |
3044 | * |
3045 | * trustee CPU draining |
3046 | * took over down complete |
3047 | * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE |
3048 | * | | ^ |
3049 | * | CPU is back online v return workers | |
3050 | * ----------------> RELEASE -------------- |
3051 | */ |
3052 | |
3053 | /** |
3054 | * trustee_wait_event_timeout - timed event wait for trustee |
3055 | * @cond: condition to wait for |
3056 | * @timeout: timeout in jiffies |
3057 | * |
3058 | * wait_event_timeout() for trustee to use. Handles locking and |
3059 | * checks for RELEASE request. |
3060 | * |
3061 | * CONTEXT: |
3062 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
3063 | * multiple times. To be used by trustee. |
3064 | * |
3065 | * RETURNS: |
3066 | * Positive indicating left time if @cond is satisfied, 0 if timed |
3067 | * out, -1 if canceled. |
3068 | */ |
3069 | #define trustee_wait_event_timeout(cond, timeout) ({ \ |
3070 | long __ret = (timeout); \ |
3071 | while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ |
3072 | __ret) { \ |
3073 | spin_unlock_irq(&gcwq->lock); \ |
3074 | __wait_event_timeout(gcwq->trustee_wait, (cond) || \ |
3075 | (gcwq->trustee_state == TRUSTEE_RELEASE), \ |
3076 | __ret); \ |
3077 | spin_lock_irq(&gcwq->lock); \ |
3078 | } \ |
3079 | gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ |
3080 | }) |
3081 | |
3082 | /** |
3083 | * trustee_wait_event - event wait for trustee |
3084 | * @cond: condition to wait for |
3085 | * |
3086 | * wait_event() for trustee to use. Automatically handles locking and |
3087 | * checks for CANCEL request. |
3088 | * |
3089 | * CONTEXT: |
3090 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
3091 | * multiple times. To be used by trustee. |
3092 | * |
3093 | * RETURNS: |
3094 | * 0 if @cond is satisfied, -1 if canceled. |
3095 | */ |
3096 | #define trustee_wait_event(cond) ({ \ |
3097 | long __ret1; \ |
3098 | __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ |
3099 | __ret1 < 0 ? -1 : 0; \ |
3100 | }) |
3101 | |
3102 | static int __cpuinit trustee_thread(void *__gcwq) |
3103 | { |
3104 | struct global_cwq *gcwq = __gcwq; |
3105 | struct worker *worker; |
3106 | struct work_struct *work; |
3107 | struct hlist_node *pos; |
3108 | long rc; |
3109 | int i; |
3110 | |
3111 | BUG_ON(gcwq->cpu != smp_processor_id()); |
3112 | |
3113 | spin_lock_irq(&gcwq->lock); |
3114 | /* |
3115 | * Claim the manager position and make all workers rogue. |
3116 | * Trustee must be bound to the target cpu and can't be |
3117 | * cancelled. |
3118 | */ |
3119 | BUG_ON(gcwq->cpu != smp_processor_id()); |
3120 | rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS)); |
3121 | BUG_ON(rc < 0); |
3122 | |
3123 | gcwq->flags |= GCWQ_MANAGING_WORKERS; |
3124 | |
3125 | list_for_each_entry(worker, &gcwq->idle_list, entry) |
3126 | worker->flags |= WORKER_ROGUE; |
3127 | |
3128 | for_each_busy_worker(worker, i, pos, gcwq) |
3129 | worker->flags |= WORKER_ROGUE; |
3130 | |
3131 | /* |
3132 | * Call schedule() so that we cross rq->lock and thus can |
3133 | * guarantee sched callbacks see the rogue flag. This is |
3134 | * necessary as scheduler callbacks may be invoked from other |
3135 | * cpus. |
3136 | */ |
3137 | spin_unlock_irq(&gcwq->lock); |
3138 | schedule(); |
3139 | spin_lock_irq(&gcwq->lock); |
3140 | |
3141 | /* |
3142 | * Sched callbacks are disabled now. Zap nr_running. After |
3143 | * this, nr_running stays zero and need_more_worker() and |
3144 | * keep_working() are always true as long as the worklist is |
3145 | * not empty. |
3146 | */ |
3147 | atomic_set(get_gcwq_nr_running(gcwq->cpu), 0); |
3148 | |
3149 | spin_unlock_irq(&gcwq->lock); |
3150 | del_timer_sync(&gcwq->idle_timer); |
3151 | spin_lock_irq(&gcwq->lock); |
3152 | |
3153 | /* |
3154 | * We're now in charge. Notify and proceed to drain. We need |
3155 | * to keep the gcwq running during the whole CPU down |
3156 | * procedure as other cpu hotunplug callbacks may need to |
3157 | * flush currently running tasks. |
3158 | */ |
3159 | gcwq->trustee_state = TRUSTEE_IN_CHARGE; |
3160 | wake_up_all(&gcwq->trustee_wait); |
3161 | |
3162 | /* |
3163 | * The original cpu is in the process of dying and may go away |
3164 | * anytime now. When that happens, we and all workers would |
3165 | * be migrated to other cpus. Try draining any left work. We |
3166 | * want to get it over with ASAP - spam rescuers, wake up as |
3167 | * many idlers as necessary and create new ones till the |
3168 | * worklist is empty. Note that if the gcwq is frozen, there |
3169 | * may be frozen works in freezeable cwqs. Don't declare |
3170 | * completion while frozen. |
3171 | */ |
3172 | while (gcwq->nr_workers != gcwq->nr_idle || |
3173 | gcwq->flags & GCWQ_FREEZING || |
3174 | gcwq->trustee_state == TRUSTEE_IN_CHARGE) { |
3175 | int nr_works = 0; |
3176 | |
3177 | list_for_each_entry(work, &gcwq->worklist, entry) { |
3178 | send_mayday(work); |
3179 | nr_works++; |
3180 | } |
3181 | |
3182 | list_for_each_entry(worker, &gcwq->idle_list, entry) { |
3183 | if (!nr_works--) |
3184 | break; |
3185 | wake_up_process(worker->task); |
3186 | } |
3187 | |
3188 | if (need_to_create_worker(gcwq)) { |
3189 | spin_unlock_irq(&gcwq->lock); |
3190 | worker = create_worker(gcwq, false); |
3191 | spin_lock_irq(&gcwq->lock); |
3192 | if (worker) { |
3193 | worker->flags |= WORKER_ROGUE; |
3194 | start_worker(worker); |
3195 | } |
3196 | } |
3197 | |
3198 | /* give a breather */ |
3199 | if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) |
3200 | break; |
3201 | } |
3202 | |
3203 | /* |
3204 | * Either all works have been scheduled and cpu is down, or |
3205 | * cpu down has already been canceled. Wait for and butcher |
3206 | * all workers till we're canceled. |
3207 | */ |
3208 | do { |
3209 | rc = trustee_wait_event(!list_empty(&gcwq->idle_list)); |
3210 | while (!list_empty(&gcwq->idle_list)) |
3211 | destroy_worker(list_first_entry(&gcwq->idle_list, |
3212 | struct worker, entry)); |
3213 | } while (gcwq->nr_workers && rc >= 0); |
3214 | |
3215 | /* |
3216 | * At this point, either draining has completed and no worker |
3217 | * is left, or cpu down has been canceled or the cpu is being |
3218 | * brought back up. There shouldn't be any idle one left. |
3219 | * Tell the remaining busy ones to rebind once it finishes the |
3220 | * currently scheduled works by scheduling the rebind_work. |
3221 | */ |
3222 | WARN_ON(!list_empty(&gcwq->idle_list)); |
3223 | |
3224 | for_each_busy_worker(worker, i, pos, gcwq) { |
3225 | struct work_struct *rebind_work = &worker->rebind_work; |
3226 | |
3227 | /* |
3228 | * Rebind_work may race with future cpu hotplug |
3229 | * operations. Use a separate flag to mark that |
3230 | * rebinding is scheduled. |
3231 | */ |
3232 | worker->flags |= WORKER_REBIND; |
3233 | worker->flags &= ~WORKER_ROGUE; |
3234 | |
3235 | /* queue rebind_work, wq doesn't matter, use the default one */ |
3236 | if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, |
3237 | work_data_bits(rebind_work))) |
3238 | continue; |
3239 | |
3240 | debug_work_activate(rebind_work); |
3241 | insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work, |
3242 | worker->scheduled.next, |
3243 | work_color_to_flags(WORK_NO_COLOR)); |
3244 | } |
3245 | |
3246 | /* relinquish manager role */ |
3247 | gcwq->flags &= ~GCWQ_MANAGING_WORKERS; |
3248 | |
3249 | /* notify completion */ |
3250 | gcwq->trustee = NULL; |
3251 | gcwq->trustee_state = TRUSTEE_DONE; |
3252 | wake_up_all(&gcwq->trustee_wait); |
3253 | spin_unlock_irq(&gcwq->lock); |
3254 | return 0; |
3255 | } |
3256 | |
3257 | /** |
3258 | * wait_trustee_state - wait for trustee to enter the specified state |
3259 | * @gcwq: gcwq the trustee of interest belongs to |
3260 | * @state: target state to wait for |
3261 | * |
3262 | * Wait for the trustee to reach @state. DONE is already matched. |
3263 | * |
3264 | * CONTEXT: |
3265 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
3266 | * multiple times. To be used by cpu_callback. |
3267 | */ |
3268 | static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) |
3269 | __releases(&gcwq->lock) |
3270 | __acquires(&gcwq->lock) |
3271 | { |
3272 | if (!(gcwq->trustee_state == state || |
3273 | gcwq->trustee_state == TRUSTEE_DONE)) { |
3274 | spin_unlock_irq(&gcwq->lock); |
3275 | __wait_event(gcwq->trustee_wait, |
3276 | gcwq->trustee_state == state || |
3277 | gcwq->trustee_state == TRUSTEE_DONE); |
3278 | spin_lock_irq(&gcwq->lock); |
3279 | } |
3280 | } |
3281 | |
3282 | static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, |
3283 | unsigned long action, |
3284 | void *hcpu) |
3285 | { |
3286 | unsigned int cpu = (unsigned long)hcpu; |
3287 | struct global_cwq *gcwq = get_gcwq(cpu); |
3288 | struct task_struct *new_trustee = NULL; |
3289 | struct worker *uninitialized_var(new_worker); |
3290 | unsigned long flags; |
3291 | |
3292 | action &= ~CPU_TASKS_FROZEN; |
3293 | |
3294 | switch (action) { |
3295 | case CPU_DOWN_PREPARE: |
3296 | new_trustee = kthread_create(trustee_thread, gcwq, |
3297 | "workqueue_trustee/%d\n", cpu); |
3298 | if (IS_ERR(new_trustee)) |
3299 | return notifier_from_errno(PTR_ERR(new_trustee)); |
3300 | kthread_bind(new_trustee, cpu); |
3301 | /* fall through */ |
3302 | case CPU_UP_PREPARE: |
3303 | BUG_ON(gcwq->first_idle); |
3304 | new_worker = create_worker(gcwq, false); |
3305 | if (!new_worker) { |
3306 | if (new_trustee) |
3307 | kthread_stop(new_trustee); |
3308 | return NOTIFY_BAD; |
3309 | } |
3310 | } |
3311 | |
3312 | /* some are called w/ irq disabled, don't disturb irq status */ |
3313 | spin_lock_irqsave(&gcwq->lock, flags); |
3314 | |
3315 | switch (action) { |
3316 | case CPU_DOWN_PREPARE: |
3317 | /* initialize trustee and tell it to acquire the gcwq */ |
3318 | BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); |
3319 | gcwq->trustee = new_trustee; |
3320 | gcwq->trustee_state = TRUSTEE_START; |
3321 | wake_up_process(gcwq->trustee); |
3322 | wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); |
3323 | /* fall through */ |
3324 | case CPU_UP_PREPARE: |
3325 | BUG_ON(gcwq->first_idle); |
3326 | gcwq->first_idle = new_worker; |
3327 | break; |
3328 | |
3329 | case CPU_DYING: |
3330 | /* |
3331 | * Before this, the trustee and all workers except for |
3332 | * the ones which are still executing works from |
3333 | * before the last CPU down must be on the cpu. After |
3334 | * this, they'll all be diasporas. |
3335 | */ |
3336 | gcwq->flags |= GCWQ_DISASSOCIATED; |
3337 | break; |
3338 | |
3339 | case CPU_POST_DEAD: |
3340 | gcwq->trustee_state = TRUSTEE_BUTCHER; |
3341 | /* fall through */ |
3342 | case CPU_UP_CANCELED: |
3343 | destroy_worker(gcwq->first_idle); |
3344 | gcwq->first_idle = NULL; |
3345 | break; |
3346 | |
3347 | case CPU_DOWN_FAILED: |
3348 | case CPU_ONLINE: |
3349 | gcwq->flags &= ~GCWQ_DISASSOCIATED; |
3350 | if (gcwq->trustee_state != TRUSTEE_DONE) { |
3351 | gcwq->trustee_state = TRUSTEE_RELEASE; |
3352 | wake_up_process(gcwq->trustee); |
3353 | wait_trustee_state(gcwq, TRUSTEE_DONE); |
3354 | } |
3355 | |
3356 | /* |
3357 | * Trustee is done and there might be no worker left. |
3358 | * Put the first_idle in and request a real manager to |
3359 | * take a look. |
3360 | */ |
3361 | spin_unlock_irq(&gcwq->lock); |
3362 | kthread_bind(gcwq->first_idle->task, cpu); |
3363 | spin_lock_irq(&gcwq->lock); |
3364 | gcwq->flags |= GCWQ_MANAGE_WORKERS; |
3365 | start_worker(gcwq->first_idle); |
3366 | gcwq->first_idle = NULL; |
3367 | break; |
3368 | } |
3369 | |
3370 | spin_unlock_irqrestore(&gcwq->lock, flags); |
3371 | |
3372 | return notifier_from_errno(0); |
3373 | } |
3374 | |
3375 | #ifdef CONFIG_SMP |
3376 | |
3377 | struct work_for_cpu { |
3378 | struct completion completion; |
3379 | long (*fn)(void *); |
3380 | void *arg; |
3381 | long ret; |
3382 | }; |
3383 | |
3384 | static int do_work_for_cpu(void *_wfc) |
3385 | { |
3386 | struct work_for_cpu *wfc = _wfc; |
3387 | wfc->ret = wfc->fn(wfc->arg); |
3388 | complete(&wfc->completion); |
3389 | return 0; |
3390 | } |
3391 | |
3392 | /** |
3393 | * work_on_cpu - run a function in user context on a particular cpu |
3394 | * @cpu: the cpu to run on |
3395 | * @fn: the function to run |
3396 | * @arg: the function arg |
3397 | * |
3398 | * This will return the value @fn returns. |
3399 | * It is up to the caller to ensure that the cpu doesn't go offline. |
3400 | * The caller must not hold any locks which would prevent @fn from completing. |
3401 | */ |
3402 | long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) |
3403 | { |
3404 | struct task_struct *sub_thread; |
3405 | struct work_for_cpu wfc = { |
3406 | .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), |
3407 | .fn = fn, |
3408 | .arg = arg, |
3409 | }; |
3410 | |
3411 | sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); |
3412 | if (IS_ERR(sub_thread)) |
3413 | return PTR_ERR(sub_thread); |
3414 | kthread_bind(sub_thread, cpu); |
3415 | wake_up_process(sub_thread); |
3416 | wait_for_completion(&wfc.completion); |
3417 | return wfc.ret; |
3418 | } |
3419 | EXPORT_SYMBOL_GPL(work_on_cpu); |
3420 | #endif /* CONFIG_SMP */ |
3421 | |
3422 | #ifdef CONFIG_FREEZER |
3423 | |
3424 | /** |
3425 | * freeze_workqueues_begin - begin freezing workqueues |
3426 | * |
3427 | * Start freezing workqueues. After this function returns, all |
3428 | * freezeable workqueues will queue new works to their frozen_works |
3429 | * list instead of gcwq->worklist. |
3430 | * |
3431 | * CONTEXT: |
3432 | * Grabs and releases workqueue_lock and gcwq->lock's. |
3433 | */ |
3434 | void freeze_workqueues_begin(void) |
3435 | { |
3436 | unsigned int cpu; |
3437 | |
3438 | spin_lock(&workqueue_lock); |
3439 | |
3440 | BUG_ON(workqueue_freezing); |
3441 | workqueue_freezing = true; |
3442 | |
3443 | for_each_gcwq_cpu(cpu) { |
3444 | struct global_cwq *gcwq = get_gcwq(cpu); |
3445 | struct workqueue_struct *wq; |
3446 | |
3447 | spin_lock_irq(&gcwq->lock); |
3448 | |
3449 | BUG_ON(gcwq->flags & GCWQ_FREEZING); |
3450 | gcwq->flags |= GCWQ_FREEZING; |
3451 | |
3452 | list_for_each_entry(wq, &workqueues, list) { |
3453 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3454 | |
3455 | if (cwq && wq->flags & WQ_FREEZEABLE) |
3456 | cwq->max_active = 0; |
3457 | } |
3458 | |
3459 | spin_unlock_irq(&gcwq->lock); |
3460 | } |
3461 | |
3462 | spin_unlock(&workqueue_lock); |
3463 | } |
3464 | |
3465 | /** |
3466 | * freeze_workqueues_busy - are freezeable workqueues still busy? |
3467 | * |
3468 | * Check whether freezing is complete. This function must be called |
3469 | * between freeze_workqueues_begin() and thaw_workqueues(). |
3470 | * |
3471 | * CONTEXT: |
3472 | * Grabs and releases workqueue_lock. |
3473 | * |
3474 | * RETURNS: |
3475 | * %true if some freezeable workqueues are still busy. %false if |
3476 | * freezing is complete. |
3477 | */ |
3478 | bool freeze_workqueues_busy(void) |
3479 | { |
3480 | unsigned int cpu; |
3481 | bool busy = false; |
3482 | |
3483 | spin_lock(&workqueue_lock); |
3484 | |
3485 | BUG_ON(!workqueue_freezing); |
3486 | |
3487 | for_each_gcwq_cpu(cpu) { |
3488 | struct workqueue_struct *wq; |
3489 | /* |
3490 | * nr_active is monotonically decreasing. It's safe |
3491 | * to peek without lock. |
3492 | */ |
3493 | list_for_each_entry(wq, &workqueues, list) { |
3494 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3495 | |
3496 | if (!cwq || !(wq->flags & WQ_FREEZEABLE)) |
3497 | continue; |
3498 | |
3499 | BUG_ON(cwq->nr_active < 0); |
3500 | if (cwq->nr_active) { |
3501 | busy = true; |
3502 | goto out_unlock; |
3503 | } |
3504 | } |
3505 | } |
3506 | out_unlock: |
3507 | spin_unlock(&workqueue_lock); |
3508 | return busy; |
3509 | } |
3510 | |
3511 | /** |
3512 | * thaw_workqueues - thaw workqueues |
3513 | * |
3514 | * Thaw workqueues. Normal queueing is restored and all collected |
3515 | * frozen works are transferred to their respective gcwq worklists. |
3516 | * |
3517 | * CONTEXT: |
3518 | * Grabs and releases workqueue_lock and gcwq->lock's. |
3519 | */ |
3520 | void thaw_workqueues(void) |
3521 | { |
3522 | unsigned int cpu; |
3523 | |
3524 | spin_lock(&workqueue_lock); |
3525 | |
3526 | if (!workqueue_freezing) |
3527 | goto out_unlock; |
3528 | |
3529 | for_each_gcwq_cpu(cpu) { |
3530 | struct global_cwq *gcwq = get_gcwq(cpu); |
3531 | struct workqueue_struct *wq; |
3532 | |
3533 | spin_lock_irq(&gcwq->lock); |
3534 | |
3535 | BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); |
3536 | gcwq->flags &= ~GCWQ_FREEZING; |
3537 | |
3538 | list_for_each_entry(wq, &workqueues, list) { |
3539 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
3540 | |
3541 | if (!cwq || !(wq->flags & WQ_FREEZEABLE)) |
3542 | continue; |
3543 | |
3544 | /* restore max_active and repopulate worklist */ |
3545 | cwq->max_active = wq->saved_max_active; |
3546 | |
3547 | while (!list_empty(&cwq->delayed_works) && |
3548 | cwq->nr_active < cwq->max_active) |
3549 | cwq_activate_first_delayed(cwq); |
3550 | } |
3551 | |
3552 | wake_up_worker(gcwq); |
3553 | |
3554 | spin_unlock_irq(&gcwq->lock); |
3555 | } |
3556 | |
3557 | workqueue_freezing = false; |
3558 | out_unlock: |
3559 | spin_unlock(&workqueue_lock); |
3560 | } |
3561 | #endif /* CONFIG_FREEZER */ |
3562 | |
3563 | static int __init init_workqueues(void) |
3564 | { |
3565 | unsigned int cpu; |
3566 | int i; |
3567 | |
3568 | cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); |
3569 | |
3570 | /* initialize gcwqs */ |
3571 | for_each_gcwq_cpu(cpu) { |
3572 | struct global_cwq *gcwq = get_gcwq(cpu); |
3573 | |
3574 | spin_lock_init(&gcwq->lock); |
3575 | INIT_LIST_HEAD(&gcwq->worklist); |
3576 | gcwq->cpu = cpu; |
3577 | gcwq->flags |= GCWQ_DISASSOCIATED; |
3578 | |
3579 | INIT_LIST_HEAD(&gcwq->idle_list); |
3580 | for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) |
3581 | INIT_HLIST_HEAD(&gcwq->busy_hash[i]); |
3582 | |
3583 | init_timer_deferrable(&gcwq->idle_timer); |
3584 | gcwq->idle_timer.function = idle_worker_timeout; |
3585 | gcwq->idle_timer.data = (unsigned long)gcwq; |
3586 | |
3587 | setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout, |
3588 | (unsigned long)gcwq); |
3589 | |
3590 | ida_init(&gcwq->worker_ida); |
3591 | |
3592 | gcwq->trustee_state = TRUSTEE_DONE; |
3593 | init_waitqueue_head(&gcwq->trustee_wait); |
3594 | } |
3595 | |
3596 | /* create the initial worker */ |
3597 | for_each_online_gcwq_cpu(cpu) { |
3598 | struct global_cwq *gcwq = get_gcwq(cpu); |
3599 | struct worker *worker; |
3600 | |
3601 | if (cpu != WORK_CPU_UNBOUND) |
3602 | gcwq->flags &= ~GCWQ_DISASSOCIATED; |
3603 | worker = create_worker(gcwq, true); |
3604 | BUG_ON(!worker); |
3605 | spin_lock_irq(&gcwq->lock); |
3606 | start_worker(worker); |
3607 | spin_unlock_irq(&gcwq->lock); |
3608 | } |
3609 | |
3610 | system_wq = alloc_workqueue("events", 0, 0); |
3611 | system_long_wq = alloc_workqueue("events_long", 0, 0); |
3612 | system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); |
3613 | system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, |
3614 | WQ_UNBOUND_MAX_ACTIVE); |
3615 | BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq); |
3616 | return 0; |
3617 | } |
3618 | early_initcall(init_workqueues); |
3619 |
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v2.6.34-rc5
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