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1da177e4 LT |
1 | /* |
2 | * linux/kernel/workqueue.c | |
3 | * | |
4 | * Generic mechanism for defining kernel helper threads for running | |
5 | * arbitrary tasks in process context. | |
6 | * | |
7 | * Started by Ingo Molnar, Copyright (C) 2002 | |
8 | * | |
9 | * Derived from the taskqueue/keventd code by: | |
10 | * | |
11 | * David Woodhouse <dwmw2@infradead.org> | |
e1f8e874 | 12 | * Andrew Morton |
1da177e4 LT |
13 | * Kai Petzke <wpp@marie.physik.tu-berlin.de> |
14 | * Theodore Ts'o <tytso@mit.edu> | |
89ada679 | 15 | * |
cde53535 | 16 | * Made to use alloc_percpu by Christoph Lameter. |
1da177e4 LT |
17 | */ |
18 | ||
19 | #include <linux/module.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/sched.h> | |
22 | #include <linux/init.h> | |
23 | #include <linux/signal.h> | |
24 | #include <linux/completion.h> | |
25 | #include <linux/workqueue.h> | |
26 | #include <linux/slab.h> | |
27 | #include <linux/cpu.h> | |
28 | #include <linux/notifier.h> | |
29 | #include <linux/kthread.h> | |
1fa44eca | 30 | #include <linux/hardirq.h> |
46934023 | 31 | #include <linux/mempolicy.h> |
341a5958 | 32 | #include <linux/freezer.h> |
d5abe669 PZ |
33 | #include <linux/kallsyms.h> |
34 | #include <linux/debug_locks.h> | |
4e6045f1 | 35 | #include <linux/lockdep.h> |
c34056a3 | 36 | #include <linux/idr.h> |
e22bee78 | 37 | |
e36c886a AV |
38 | #define CREATE_TRACE_POINTS |
39 | #include <trace/events/workqueue.h> | |
40 | ||
e22bee78 | 41 | #include "workqueue_sched.h" |
1da177e4 | 42 | |
c8e55f36 | 43 | enum { |
db7bccf4 | 44 | /* global_cwq flags */ |
e22bee78 TH |
45 | GCWQ_MANAGE_WORKERS = 1 << 0, /* need to manage workers */ |
46 | GCWQ_MANAGING_WORKERS = 1 << 1, /* managing workers */ | |
47 | GCWQ_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ | |
db7bccf4 | 48 | GCWQ_FREEZING = 1 << 3, /* freeze in progress */ |
649027d7 | 49 | GCWQ_HIGHPRI_PENDING = 1 << 4, /* highpri works on queue */ |
db7bccf4 | 50 | |
c8e55f36 TH |
51 | /* worker flags */ |
52 | WORKER_STARTED = 1 << 0, /* started */ | |
53 | WORKER_DIE = 1 << 1, /* die die die */ | |
54 | WORKER_IDLE = 1 << 2, /* is idle */ | |
e22bee78 | 55 | WORKER_PREP = 1 << 3, /* preparing to run works */ |
db7bccf4 | 56 | WORKER_ROGUE = 1 << 4, /* not bound to any cpu */ |
e22bee78 | 57 | WORKER_REBIND = 1 << 5, /* mom is home, come back */ |
fb0e7beb | 58 | WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ |
f3421797 | 59 | WORKER_UNBOUND = 1 << 7, /* worker is unbound */ |
e22bee78 | 60 | |
fb0e7beb | 61 | WORKER_NOT_RUNNING = WORKER_PREP | WORKER_ROGUE | WORKER_REBIND | |
f3421797 | 62 | WORKER_CPU_INTENSIVE | WORKER_UNBOUND, |
db7bccf4 TH |
63 | |
64 | /* gcwq->trustee_state */ | |
65 | TRUSTEE_START = 0, /* start */ | |
66 | TRUSTEE_IN_CHARGE = 1, /* trustee in charge of gcwq */ | |
67 | TRUSTEE_BUTCHER = 2, /* butcher workers */ | |
68 | TRUSTEE_RELEASE = 3, /* release workers */ | |
69 | TRUSTEE_DONE = 4, /* trustee is done */ | |
c8e55f36 TH |
70 | |
71 | BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ | |
72 | BUSY_WORKER_HASH_SIZE = 1 << BUSY_WORKER_HASH_ORDER, | |
73 | BUSY_WORKER_HASH_MASK = BUSY_WORKER_HASH_SIZE - 1, | |
db7bccf4 | 74 | |
e22bee78 TH |
75 | MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ |
76 | IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ | |
77 | ||
78 | MAYDAY_INITIAL_TIMEOUT = HZ / 100, /* call for help after 10ms */ | |
79 | MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ | |
80 | CREATE_COOLDOWN = HZ, /* time to breath after fail */ | |
db7bccf4 | 81 | TRUSTEE_COOLDOWN = HZ / 10, /* for trustee draining */ |
e22bee78 TH |
82 | |
83 | /* | |
84 | * Rescue workers are used only on emergencies and shared by | |
85 | * all cpus. Give -20. | |
86 | */ | |
87 | RESCUER_NICE_LEVEL = -20, | |
c8e55f36 | 88 | }; |
1da177e4 LT |
89 | |
90 | /* | |
4690c4ab TH |
91 | * Structure fields follow one of the following exclusion rules. |
92 | * | |
93 | * I: Set during initialization and read-only afterwards. | |
94 | * | |
e22bee78 TH |
95 | * P: Preemption protected. Disabling preemption is enough and should |
96 | * only be modified and accessed from the local cpu. | |
97 | * | |
8b03ae3c | 98 | * L: gcwq->lock protected. Access with gcwq->lock held. |
4690c4ab | 99 | * |
e22bee78 TH |
100 | * X: During normal operation, modification requires gcwq->lock and |
101 | * should be done only from local cpu. Either disabling preemption | |
102 | * on local cpu or grabbing gcwq->lock is enough for read access. | |
f3421797 | 103 | * If GCWQ_DISASSOCIATED is set, it's identical to L. |
e22bee78 | 104 | * |
73f53c4a TH |
105 | * F: wq->flush_mutex protected. |
106 | * | |
4690c4ab | 107 | * W: workqueue_lock protected. |
1da177e4 | 108 | */ |
1da177e4 | 109 | |
8b03ae3c | 110 | struct global_cwq; |
1da177e4 | 111 | |
e22bee78 TH |
112 | /* |
113 | * The poor guys doing the actual heavy lifting. All on-duty workers | |
114 | * are either serving the manager role, on idle list or on busy hash. | |
115 | */ | |
c34056a3 | 116 | struct worker { |
c8e55f36 TH |
117 | /* on idle list while idle, on busy hash table while busy */ |
118 | union { | |
119 | struct list_head entry; /* L: while idle */ | |
120 | struct hlist_node hentry; /* L: while busy */ | |
121 | }; | |
1da177e4 | 122 | |
c34056a3 | 123 | struct work_struct *current_work; /* L: work being processed */ |
8cca0eea | 124 | struct cpu_workqueue_struct *current_cwq; /* L: current_work's cwq */ |
affee4b2 | 125 | struct list_head scheduled; /* L: scheduled works */ |
c34056a3 | 126 | struct task_struct *task; /* I: worker task */ |
8b03ae3c | 127 | struct global_cwq *gcwq; /* I: the associated gcwq */ |
e22bee78 TH |
128 | /* 64 bytes boundary on 64bit, 32 on 32bit */ |
129 | unsigned long last_active; /* L: last active timestamp */ | |
130 | unsigned int flags; /* X: flags */ | |
c34056a3 | 131 | int id; /* I: worker id */ |
e22bee78 | 132 | struct work_struct rebind_work; /* L: rebind worker to cpu */ |
c34056a3 TH |
133 | }; |
134 | ||
8b03ae3c | 135 | /* |
e22bee78 TH |
136 | * Global per-cpu workqueue. There's one and only one for each cpu |
137 | * and all works are queued and processed here regardless of their | |
138 | * target workqueues. | |
8b03ae3c TH |
139 | */ |
140 | struct global_cwq { | |
141 | spinlock_t lock; /* the gcwq lock */ | |
7e11629d | 142 | struct list_head worklist; /* L: list of pending works */ |
8b03ae3c | 143 | unsigned int cpu; /* I: the associated cpu */ |
db7bccf4 | 144 | unsigned int flags; /* L: GCWQ_* flags */ |
c8e55f36 TH |
145 | |
146 | int nr_workers; /* L: total number of workers */ | |
147 | int nr_idle; /* L: currently idle ones */ | |
148 | ||
149 | /* workers are chained either in the idle_list or busy_hash */ | |
e22bee78 | 150 | struct list_head idle_list; /* X: list of idle workers */ |
c8e55f36 TH |
151 | struct hlist_head busy_hash[BUSY_WORKER_HASH_SIZE]; |
152 | /* L: hash of busy workers */ | |
153 | ||
e22bee78 TH |
154 | struct timer_list idle_timer; /* L: worker idle timeout */ |
155 | struct timer_list mayday_timer; /* L: SOS timer for dworkers */ | |
156 | ||
8b03ae3c | 157 | struct ida worker_ida; /* L: for worker IDs */ |
db7bccf4 TH |
158 | |
159 | struct task_struct *trustee; /* L: for gcwq shutdown */ | |
160 | unsigned int trustee_state; /* L: trustee state */ | |
161 | wait_queue_head_t trustee_wait; /* trustee wait */ | |
e22bee78 | 162 | struct worker *first_idle; /* L: first idle worker */ |
8b03ae3c TH |
163 | } ____cacheline_aligned_in_smp; |
164 | ||
1da177e4 | 165 | /* |
502ca9d8 | 166 | * The per-CPU workqueue. The lower WORK_STRUCT_FLAG_BITS of |
0f900049 TH |
167 | * work_struct->data are used for flags and thus cwqs need to be |
168 | * aligned at two's power of the number of flag bits. | |
1da177e4 LT |
169 | */ |
170 | struct cpu_workqueue_struct { | |
8b03ae3c | 171 | struct global_cwq *gcwq; /* I: the associated gcwq */ |
4690c4ab | 172 | struct workqueue_struct *wq; /* I: the owning workqueue */ |
73f53c4a TH |
173 | int work_color; /* L: current color */ |
174 | int flush_color; /* L: flushing color */ | |
175 | int nr_in_flight[WORK_NR_COLORS]; | |
176 | /* L: nr of in_flight works */ | |
1e19ffc6 | 177 | int nr_active; /* L: nr of active works */ |
a0a1a5fd | 178 | int max_active; /* L: max active works */ |
1e19ffc6 | 179 | struct list_head delayed_works; /* L: delayed works */ |
0f900049 | 180 | }; |
1da177e4 | 181 | |
73f53c4a TH |
182 | /* |
183 | * Structure used to wait for workqueue flush. | |
184 | */ | |
185 | struct wq_flusher { | |
186 | struct list_head list; /* F: list of flushers */ | |
187 | int flush_color; /* F: flush color waiting for */ | |
188 | struct completion done; /* flush completion */ | |
189 | }; | |
190 | ||
f2e005aa TH |
191 | /* |
192 | * All cpumasks are assumed to be always set on UP and thus can't be | |
193 | * used to determine whether there's something to be done. | |
194 | */ | |
195 | #ifdef CONFIG_SMP | |
196 | typedef cpumask_var_t mayday_mask_t; | |
197 | #define mayday_test_and_set_cpu(cpu, mask) \ | |
198 | cpumask_test_and_set_cpu((cpu), (mask)) | |
199 | #define mayday_clear_cpu(cpu, mask) cpumask_clear_cpu((cpu), (mask)) | |
200 | #define for_each_mayday_cpu(cpu, mask) for_each_cpu((cpu), (mask)) | |
201 | #define alloc_mayday_mask(maskp, gfp) alloc_cpumask_var((maskp), (gfp)) | |
202 | #define free_mayday_mask(mask) free_cpumask_var((mask)) | |
203 | #else | |
204 | typedef unsigned long mayday_mask_t; | |
205 | #define mayday_test_and_set_cpu(cpu, mask) test_and_set_bit(0, &(mask)) | |
206 | #define mayday_clear_cpu(cpu, mask) clear_bit(0, &(mask)) | |
207 | #define for_each_mayday_cpu(cpu, mask) if ((cpu) = 0, (mask)) | |
208 | #define alloc_mayday_mask(maskp, gfp) true | |
209 | #define free_mayday_mask(mask) do { } while (0) | |
210 | #endif | |
1da177e4 LT |
211 | |
212 | /* | |
213 | * The externally visible workqueue abstraction is an array of | |
214 | * per-CPU workqueues: | |
215 | */ | |
216 | struct workqueue_struct { | |
97e37d7b | 217 | unsigned int flags; /* I: WQ_* flags */ |
bdbc5dd7 TH |
218 | union { |
219 | struct cpu_workqueue_struct __percpu *pcpu; | |
220 | struct cpu_workqueue_struct *single; | |
221 | unsigned long v; | |
222 | } cpu_wq; /* I: cwq's */ | |
4690c4ab | 223 | struct list_head list; /* W: list of all workqueues */ |
73f53c4a TH |
224 | |
225 | struct mutex flush_mutex; /* protects wq flushing */ | |
226 | int work_color; /* F: current work color */ | |
227 | int flush_color; /* F: current flush color */ | |
228 | atomic_t nr_cwqs_to_flush; /* flush in progress */ | |
229 | struct wq_flusher *first_flusher; /* F: first flusher */ | |
230 | struct list_head flusher_queue; /* F: flush waiters */ | |
231 | struct list_head flusher_overflow; /* F: flush overflow list */ | |
232 | ||
f2e005aa | 233 | mayday_mask_t mayday_mask; /* cpus requesting rescue */ |
e22bee78 TH |
234 | struct worker *rescuer; /* I: rescue worker */ |
235 | ||
dcd989cb | 236 | int saved_max_active; /* W: saved cwq max_active */ |
4690c4ab | 237 | const char *name; /* I: workqueue name */ |
4e6045f1 | 238 | #ifdef CONFIG_LOCKDEP |
4690c4ab | 239 | struct lockdep_map lockdep_map; |
4e6045f1 | 240 | #endif |
1da177e4 LT |
241 | }; |
242 | ||
d320c038 TH |
243 | struct workqueue_struct *system_wq __read_mostly; |
244 | struct workqueue_struct *system_long_wq __read_mostly; | |
245 | struct workqueue_struct *system_nrt_wq __read_mostly; | |
f3421797 | 246 | struct workqueue_struct *system_unbound_wq __read_mostly; |
d320c038 TH |
247 | EXPORT_SYMBOL_GPL(system_wq); |
248 | EXPORT_SYMBOL_GPL(system_long_wq); | |
249 | EXPORT_SYMBOL_GPL(system_nrt_wq); | |
f3421797 | 250 | EXPORT_SYMBOL_GPL(system_unbound_wq); |
d320c038 | 251 | |
db7bccf4 TH |
252 | #define for_each_busy_worker(worker, i, pos, gcwq) \ |
253 | for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) \ | |
254 | hlist_for_each_entry(worker, pos, &gcwq->busy_hash[i], hentry) | |
255 | ||
f3421797 TH |
256 | static inline int __next_gcwq_cpu(int cpu, const struct cpumask *mask, |
257 | unsigned int sw) | |
258 | { | |
259 | if (cpu < nr_cpu_ids) { | |
260 | if (sw & 1) { | |
261 | cpu = cpumask_next(cpu, mask); | |
262 | if (cpu < nr_cpu_ids) | |
263 | return cpu; | |
264 | } | |
265 | if (sw & 2) | |
266 | return WORK_CPU_UNBOUND; | |
267 | } | |
268 | return WORK_CPU_NONE; | |
269 | } | |
270 | ||
271 | static inline int __next_wq_cpu(int cpu, const struct cpumask *mask, | |
272 | struct workqueue_struct *wq) | |
273 | { | |
274 | return __next_gcwq_cpu(cpu, mask, !(wq->flags & WQ_UNBOUND) ? 1 : 2); | |
275 | } | |
276 | ||
09884951 TH |
277 | /* |
278 | * CPU iterators | |
279 | * | |
280 | * An extra gcwq is defined for an invalid cpu number | |
281 | * (WORK_CPU_UNBOUND) to host workqueues which are not bound to any | |
282 | * specific CPU. The following iterators are similar to | |
283 | * for_each_*_cpu() iterators but also considers the unbound gcwq. | |
284 | * | |
285 | * for_each_gcwq_cpu() : possible CPUs + WORK_CPU_UNBOUND | |
286 | * for_each_online_gcwq_cpu() : online CPUs + WORK_CPU_UNBOUND | |
287 | * for_each_cwq_cpu() : possible CPUs for bound workqueues, | |
288 | * WORK_CPU_UNBOUND for unbound workqueues | |
289 | */ | |
f3421797 TH |
290 | #define for_each_gcwq_cpu(cpu) \ |
291 | for ((cpu) = __next_gcwq_cpu(-1, cpu_possible_mask, 3); \ | |
292 | (cpu) < WORK_CPU_NONE; \ | |
293 | (cpu) = __next_gcwq_cpu((cpu), cpu_possible_mask, 3)) | |
294 | ||
295 | #define for_each_online_gcwq_cpu(cpu) \ | |
296 | for ((cpu) = __next_gcwq_cpu(-1, cpu_online_mask, 3); \ | |
297 | (cpu) < WORK_CPU_NONE; \ | |
298 | (cpu) = __next_gcwq_cpu((cpu), cpu_online_mask, 3)) | |
299 | ||
300 | #define for_each_cwq_cpu(cpu, wq) \ | |
301 | for ((cpu) = __next_wq_cpu(-1, cpu_possible_mask, (wq)); \ | |
302 | (cpu) < WORK_CPU_NONE; \ | |
303 | (cpu) = __next_wq_cpu((cpu), cpu_possible_mask, (wq))) | |
304 | ||
a25909a4 PM |
305 | #ifdef CONFIG_LOCKDEP |
306 | /** | |
307 | * in_workqueue_context() - in context of specified workqueue? | |
308 | * @wq: the workqueue of interest | |
309 | * | |
310 | * Checks lockdep state to see if the current task is executing from | |
311 | * within a workqueue item. This function exists only if lockdep is | |
312 | * enabled. | |
313 | */ | |
314 | int in_workqueue_context(struct workqueue_struct *wq) | |
315 | { | |
316 | return lock_is_held(&wq->lockdep_map); | |
317 | } | |
318 | #endif | |
319 | ||
dc186ad7 TG |
320 | #ifdef CONFIG_DEBUG_OBJECTS_WORK |
321 | ||
322 | static struct debug_obj_descr work_debug_descr; | |
323 | ||
324 | /* | |
325 | * fixup_init is called when: | |
326 | * - an active object is initialized | |
327 | */ | |
328 | static int work_fixup_init(void *addr, enum debug_obj_state state) | |
329 | { | |
330 | struct work_struct *work = addr; | |
331 | ||
332 | switch (state) { | |
333 | case ODEBUG_STATE_ACTIVE: | |
334 | cancel_work_sync(work); | |
335 | debug_object_init(work, &work_debug_descr); | |
336 | return 1; | |
337 | default: | |
338 | return 0; | |
339 | } | |
340 | } | |
341 | ||
342 | /* | |
343 | * fixup_activate is called when: | |
344 | * - an active object is activated | |
345 | * - an unknown object is activated (might be a statically initialized object) | |
346 | */ | |
347 | static int work_fixup_activate(void *addr, enum debug_obj_state state) | |
348 | { | |
349 | struct work_struct *work = addr; | |
350 | ||
351 | switch (state) { | |
352 | ||
353 | case ODEBUG_STATE_NOTAVAILABLE: | |
354 | /* | |
355 | * This is not really a fixup. The work struct was | |
356 | * statically initialized. We just make sure that it | |
357 | * is tracked in the object tracker. | |
358 | */ | |
22df02bb | 359 | if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
dc186ad7 TG |
360 | debug_object_init(work, &work_debug_descr); |
361 | debug_object_activate(work, &work_debug_descr); | |
362 | return 0; | |
363 | } | |
364 | WARN_ON_ONCE(1); | |
365 | return 0; | |
366 | ||
367 | case ODEBUG_STATE_ACTIVE: | |
368 | WARN_ON(1); | |
369 | ||
370 | default: | |
371 | return 0; | |
372 | } | |
373 | } | |
374 | ||
375 | /* | |
376 | * fixup_free is called when: | |
377 | * - an active object is freed | |
378 | */ | |
379 | static int work_fixup_free(void *addr, enum debug_obj_state state) | |
380 | { | |
381 | struct work_struct *work = addr; | |
382 | ||
383 | switch (state) { | |
384 | case ODEBUG_STATE_ACTIVE: | |
385 | cancel_work_sync(work); | |
386 | debug_object_free(work, &work_debug_descr); | |
387 | return 1; | |
388 | default: | |
389 | return 0; | |
390 | } | |
391 | } | |
392 | ||
393 | static struct debug_obj_descr work_debug_descr = { | |
394 | .name = "work_struct", | |
395 | .fixup_init = work_fixup_init, | |
396 | .fixup_activate = work_fixup_activate, | |
397 | .fixup_free = work_fixup_free, | |
398 | }; | |
399 | ||
400 | static inline void debug_work_activate(struct work_struct *work) | |
401 | { | |
402 | debug_object_activate(work, &work_debug_descr); | |
403 | } | |
404 | ||
405 | static inline void debug_work_deactivate(struct work_struct *work) | |
406 | { | |
407 | debug_object_deactivate(work, &work_debug_descr); | |
408 | } | |
409 | ||
410 | void __init_work(struct work_struct *work, int onstack) | |
411 | { | |
412 | if (onstack) | |
413 | debug_object_init_on_stack(work, &work_debug_descr); | |
414 | else | |
415 | debug_object_init(work, &work_debug_descr); | |
416 | } | |
417 | EXPORT_SYMBOL_GPL(__init_work); | |
418 | ||
419 | void destroy_work_on_stack(struct work_struct *work) | |
420 | { | |
421 | debug_object_free(work, &work_debug_descr); | |
422 | } | |
423 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); | |
424 | ||
425 | #else | |
426 | static inline void debug_work_activate(struct work_struct *work) { } | |
427 | static inline void debug_work_deactivate(struct work_struct *work) { } | |
428 | #endif | |
429 | ||
95402b38 GS |
430 | /* Serializes the accesses to the list of workqueues. */ |
431 | static DEFINE_SPINLOCK(workqueue_lock); | |
1da177e4 | 432 | static LIST_HEAD(workqueues); |
a0a1a5fd | 433 | static bool workqueue_freezing; /* W: have wqs started freezing? */ |
c34056a3 | 434 | |
e22bee78 TH |
435 | /* |
436 | * The almighty global cpu workqueues. nr_running is the only field | |
437 | * which is expected to be used frequently by other cpus via | |
438 | * try_to_wake_up(). Put it in a separate cacheline. | |
439 | */ | |
8b03ae3c | 440 | static DEFINE_PER_CPU(struct global_cwq, global_cwq); |
e22bee78 | 441 | static DEFINE_PER_CPU_SHARED_ALIGNED(atomic_t, gcwq_nr_running); |
8b03ae3c | 442 | |
f3421797 TH |
443 | /* |
444 | * Global cpu workqueue and nr_running counter for unbound gcwq. The | |
445 | * gcwq is always online, has GCWQ_DISASSOCIATED set, and all its | |
446 | * workers have WORKER_UNBOUND set. | |
447 | */ | |
448 | static struct global_cwq unbound_global_cwq; | |
449 | static atomic_t unbound_gcwq_nr_running = ATOMIC_INIT(0); /* always 0 */ | |
450 | ||
c34056a3 | 451 | static int worker_thread(void *__worker); |
1da177e4 | 452 | |
8b03ae3c TH |
453 | static struct global_cwq *get_gcwq(unsigned int cpu) |
454 | { | |
f3421797 TH |
455 | if (cpu != WORK_CPU_UNBOUND) |
456 | return &per_cpu(global_cwq, cpu); | |
457 | else | |
458 | return &unbound_global_cwq; | |
8b03ae3c TH |
459 | } |
460 | ||
e22bee78 TH |
461 | static atomic_t *get_gcwq_nr_running(unsigned int cpu) |
462 | { | |
f3421797 TH |
463 | if (cpu != WORK_CPU_UNBOUND) |
464 | return &per_cpu(gcwq_nr_running, cpu); | |
465 | else | |
466 | return &unbound_gcwq_nr_running; | |
e22bee78 TH |
467 | } |
468 | ||
1537663f TH |
469 | static struct cpu_workqueue_struct *get_cwq(unsigned int cpu, |
470 | struct workqueue_struct *wq) | |
b1f4ec17 | 471 | { |
f3421797 TH |
472 | if (!(wq->flags & WQ_UNBOUND)) { |
473 | if (likely(cpu < nr_cpu_ids)) { | |
474 | #ifdef CONFIG_SMP | |
475 | return per_cpu_ptr(wq->cpu_wq.pcpu, cpu); | |
bdbc5dd7 | 476 | #else |
f3421797 | 477 | return wq->cpu_wq.single; |
bdbc5dd7 | 478 | #endif |
f3421797 TH |
479 | } |
480 | } else if (likely(cpu == WORK_CPU_UNBOUND)) | |
481 | return wq->cpu_wq.single; | |
482 | return NULL; | |
b1f4ec17 ON |
483 | } |
484 | ||
73f53c4a TH |
485 | static unsigned int work_color_to_flags(int color) |
486 | { | |
487 | return color << WORK_STRUCT_COLOR_SHIFT; | |
488 | } | |
489 | ||
490 | static int get_work_color(struct work_struct *work) | |
491 | { | |
492 | return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & | |
493 | ((1 << WORK_STRUCT_COLOR_BITS) - 1); | |
494 | } | |
495 | ||
496 | static int work_next_color(int color) | |
497 | { | |
498 | return (color + 1) % WORK_NR_COLORS; | |
499 | } | |
1da177e4 | 500 | |
14441960 | 501 | /* |
e120153d TH |
502 | * A work's data points to the cwq with WORK_STRUCT_CWQ set while the |
503 | * work is on queue. Once execution starts, WORK_STRUCT_CWQ is | |
504 | * cleared and the work data contains the cpu number it was last on. | |
7a22ad75 TH |
505 | * |
506 | * set_work_{cwq|cpu}() and clear_work_data() can be used to set the | |
507 | * cwq, cpu or clear work->data. These functions should only be | |
508 | * called while the work is owned - ie. while the PENDING bit is set. | |
509 | * | |
510 | * get_work_[g]cwq() can be used to obtain the gcwq or cwq | |
511 | * corresponding to a work. gcwq is available once the work has been | |
512 | * queued anywhere after initialization. cwq is available only from | |
513 | * queueing until execution starts. | |
14441960 | 514 | */ |
7a22ad75 TH |
515 | static inline void set_work_data(struct work_struct *work, unsigned long data, |
516 | unsigned long flags) | |
365970a1 | 517 | { |
4594bf15 | 518 | BUG_ON(!work_pending(work)); |
7a22ad75 TH |
519 | atomic_long_set(&work->data, data | flags | work_static(work)); |
520 | } | |
365970a1 | 521 | |
7a22ad75 TH |
522 | static void set_work_cwq(struct work_struct *work, |
523 | struct cpu_workqueue_struct *cwq, | |
524 | unsigned long extra_flags) | |
525 | { | |
526 | set_work_data(work, (unsigned long)cwq, | |
e120153d | 527 | WORK_STRUCT_PENDING | WORK_STRUCT_CWQ | extra_flags); |
365970a1 DH |
528 | } |
529 | ||
7a22ad75 TH |
530 | static void set_work_cpu(struct work_struct *work, unsigned int cpu) |
531 | { | |
532 | set_work_data(work, cpu << WORK_STRUCT_FLAG_BITS, WORK_STRUCT_PENDING); | |
533 | } | |
f756d5e2 | 534 | |
7a22ad75 | 535 | static void clear_work_data(struct work_struct *work) |
1da177e4 | 536 | { |
7a22ad75 | 537 | set_work_data(work, WORK_STRUCT_NO_CPU, 0); |
1da177e4 LT |
538 | } |
539 | ||
7a22ad75 | 540 | static struct cpu_workqueue_struct *get_work_cwq(struct work_struct *work) |
b1f4ec17 | 541 | { |
e120153d | 542 | unsigned long data = atomic_long_read(&work->data); |
7a22ad75 | 543 | |
e120153d TH |
544 | if (data & WORK_STRUCT_CWQ) |
545 | return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); | |
546 | else | |
547 | return NULL; | |
4d707b9f ON |
548 | } |
549 | ||
7a22ad75 | 550 | static struct global_cwq *get_work_gcwq(struct work_struct *work) |
365970a1 | 551 | { |
e120153d | 552 | unsigned long data = atomic_long_read(&work->data); |
7a22ad75 TH |
553 | unsigned int cpu; |
554 | ||
e120153d TH |
555 | if (data & WORK_STRUCT_CWQ) |
556 | return ((struct cpu_workqueue_struct *) | |
557 | (data & WORK_STRUCT_WQ_DATA_MASK))->gcwq; | |
7a22ad75 TH |
558 | |
559 | cpu = data >> WORK_STRUCT_FLAG_BITS; | |
bdbc5dd7 | 560 | if (cpu == WORK_CPU_NONE) |
7a22ad75 TH |
561 | return NULL; |
562 | ||
f3421797 | 563 | BUG_ON(cpu >= nr_cpu_ids && cpu != WORK_CPU_UNBOUND); |
7a22ad75 | 564 | return get_gcwq(cpu); |
b1f4ec17 ON |
565 | } |
566 | ||
e22bee78 TH |
567 | /* |
568 | * Policy functions. These define the policies on how the global | |
569 | * worker pool is managed. Unless noted otherwise, these functions | |
570 | * assume that they're being called with gcwq->lock held. | |
571 | */ | |
572 | ||
649027d7 | 573 | static bool __need_more_worker(struct global_cwq *gcwq) |
a848e3b6 | 574 | { |
649027d7 TH |
575 | return !atomic_read(get_gcwq_nr_running(gcwq->cpu)) || |
576 | gcwq->flags & GCWQ_HIGHPRI_PENDING; | |
a848e3b6 ON |
577 | } |
578 | ||
4594bf15 | 579 | /* |
e22bee78 TH |
580 | * Need to wake up a worker? Called from anything but currently |
581 | * running workers. | |
4594bf15 | 582 | */ |
e22bee78 | 583 | static bool need_more_worker(struct global_cwq *gcwq) |
365970a1 | 584 | { |
649027d7 | 585 | return !list_empty(&gcwq->worklist) && __need_more_worker(gcwq); |
e22bee78 | 586 | } |
4594bf15 | 587 | |
e22bee78 TH |
588 | /* Can I start working? Called from busy but !running workers. */ |
589 | static bool may_start_working(struct global_cwq *gcwq) | |
590 | { | |
591 | return gcwq->nr_idle; | |
592 | } | |
593 | ||
594 | /* Do I need to keep working? Called from currently running workers. */ | |
595 | static bool keep_working(struct global_cwq *gcwq) | |
596 | { | |
597 | atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); | |
598 | ||
599 | return !list_empty(&gcwq->worklist) && atomic_read(nr_running) <= 1; | |
600 | } | |
601 | ||
602 | /* Do we need a new worker? Called from manager. */ | |
603 | static bool need_to_create_worker(struct global_cwq *gcwq) | |
604 | { | |
605 | return need_more_worker(gcwq) && !may_start_working(gcwq); | |
606 | } | |
365970a1 | 607 | |
e22bee78 TH |
608 | /* Do I need to be the manager? */ |
609 | static bool need_to_manage_workers(struct global_cwq *gcwq) | |
610 | { | |
611 | return need_to_create_worker(gcwq) || gcwq->flags & GCWQ_MANAGE_WORKERS; | |
612 | } | |
613 | ||
614 | /* Do we have too many workers and should some go away? */ | |
615 | static bool too_many_workers(struct global_cwq *gcwq) | |
616 | { | |
617 | bool managing = gcwq->flags & GCWQ_MANAGING_WORKERS; | |
618 | int nr_idle = gcwq->nr_idle + managing; /* manager is considered idle */ | |
619 | int nr_busy = gcwq->nr_workers - nr_idle; | |
620 | ||
621 | return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; | |
365970a1 DH |
622 | } |
623 | ||
4d707b9f | 624 | /* |
e22bee78 TH |
625 | * Wake up functions. |
626 | */ | |
627 | ||
7e11629d TH |
628 | /* Return the first worker. Safe with preemption disabled */ |
629 | static struct worker *first_worker(struct global_cwq *gcwq) | |
630 | { | |
631 | if (unlikely(list_empty(&gcwq->idle_list))) | |
632 | return NULL; | |
633 | ||
634 | return list_first_entry(&gcwq->idle_list, struct worker, entry); | |
635 | } | |
636 | ||
637 | /** | |
638 | * wake_up_worker - wake up an idle worker | |
639 | * @gcwq: gcwq to wake worker for | |
640 | * | |
641 | * Wake up the first idle worker of @gcwq. | |
642 | * | |
643 | * CONTEXT: | |
644 | * spin_lock_irq(gcwq->lock). | |
645 | */ | |
646 | static void wake_up_worker(struct global_cwq *gcwq) | |
647 | { | |
648 | struct worker *worker = first_worker(gcwq); | |
649 | ||
650 | if (likely(worker)) | |
651 | wake_up_process(worker->task); | |
652 | } | |
653 | ||
d302f017 | 654 | /** |
e22bee78 TH |
655 | * wq_worker_waking_up - a worker is waking up |
656 | * @task: task waking up | |
657 | * @cpu: CPU @task is waking up to | |
658 | * | |
659 | * This function is called during try_to_wake_up() when a worker is | |
660 | * being awoken. | |
661 | * | |
662 | * CONTEXT: | |
663 | * spin_lock_irq(rq->lock) | |
664 | */ | |
665 | void wq_worker_waking_up(struct task_struct *task, unsigned int cpu) | |
666 | { | |
667 | struct worker *worker = kthread_data(task); | |
668 | ||
669 | if (likely(!(worker->flags & WORKER_NOT_RUNNING))) | |
670 | atomic_inc(get_gcwq_nr_running(cpu)); | |
671 | } | |
672 | ||
673 | /** | |
674 | * wq_worker_sleeping - a worker is going to sleep | |
675 | * @task: task going to sleep | |
676 | * @cpu: CPU in question, must be the current CPU number | |
677 | * | |
678 | * This function is called during schedule() when a busy worker is | |
679 | * going to sleep. Worker on the same cpu can be woken up by | |
680 | * returning pointer to its task. | |
681 | * | |
682 | * CONTEXT: | |
683 | * spin_lock_irq(rq->lock) | |
684 | * | |
685 | * RETURNS: | |
686 | * Worker task on @cpu to wake up, %NULL if none. | |
687 | */ | |
688 | struct task_struct *wq_worker_sleeping(struct task_struct *task, | |
689 | unsigned int cpu) | |
690 | { | |
691 | struct worker *worker = kthread_data(task), *to_wakeup = NULL; | |
692 | struct global_cwq *gcwq = get_gcwq(cpu); | |
693 | atomic_t *nr_running = get_gcwq_nr_running(cpu); | |
694 | ||
695 | if (unlikely(worker->flags & WORKER_NOT_RUNNING)) | |
696 | return NULL; | |
697 | ||
698 | /* this can only happen on the local cpu */ | |
699 | BUG_ON(cpu != raw_smp_processor_id()); | |
700 | ||
701 | /* | |
702 | * The counterpart of the following dec_and_test, implied mb, | |
703 | * worklist not empty test sequence is in insert_work(). | |
704 | * Please read comment there. | |
705 | * | |
706 | * NOT_RUNNING is clear. This means that trustee is not in | |
707 | * charge and we're running on the local cpu w/ rq lock held | |
708 | * and preemption disabled, which in turn means that none else | |
709 | * could be manipulating idle_list, so dereferencing idle_list | |
710 | * without gcwq lock is safe. | |
711 | */ | |
712 | if (atomic_dec_and_test(nr_running) && !list_empty(&gcwq->worklist)) | |
713 | to_wakeup = first_worker(gcwq); | |
714 | return to_wakeup ? to_wakeup->task : NULL; | |
715 | } | |
716 | ||
717 | /** | |
718 | * worker_set_flags - set worker flags and adjust nr_running accordingly | |
cb444766 | 719 | * @worker: self |
d302f017 TH |
720 | * @flags: flags to set |
721 | * @wakeup: wakeup an idle worker if necessary | |
722 | * | |
e22bee78 TH |
723 | * Set @flags in @worker->flags and adjust nr_running accordingly. If |
724 | * nr_running becomes zero and @wakeup is %true, an idle worker is | |
725 | * woken up. | |
d302f017 | 726 | * |
cb444766 TH |
727 | * CONTEXT: |
728 | * spin_lock_irq(gcwq->lock) | |
d302f017 TH |
729 | */ |
730 | static inline void worker_set_flags(struct worker *worker, unsigned int flags, | |
731 | bool wakeup) | |
732 | { | |
e22bee78 TH |
733 | struct global_cwq *gcwq = worker->gcwq; |
734 | ||
cb444766 TH |
735 | WARN_ON_ONCE(worker->task != current); |
736 | ||
e22bee78 TH |
737 | /* |
738 | * If transitioning into NOT_RUNNING, adjust nr_running and | |
739 | * wake up an idle worker as necessary if requested by | |
740 | * @wakeup. | |
741 | */ | |
742 | if ((flags & WORKER_NOT_RUNNING) && | |
743 | !(worker->flags & WORKER_NOT_RUNNING)) { | |
744 | atomic_t *nr_running = get_gcwq_nr_running(gcwq->cpu); | |
745 | ||
746 | if (wakeup) { | |
747 | if (atomic_dec_and_test(nr_running) && | |
748 | !list_empty(&gcwq->worklist)) | |
749 | wake_up_worker(gcwq); | |
750 | } else | |
751 | atomic_dec(nr_running); | |
752 | } | |
753 | ||
d302f017 TH |
754 | worker->flags |= flags; |
755 | } | |
756 | ||
757 | /** | |
e22bee78 | 758 | * worker_clr_flags - clear worker flags and adjust nr_running accordingly |
cb444766 | 759 | * @worker: self |
d302f017 TH |
760 | * @flags: flags to clear |
761 | * | |
e22bee78 | 762 | * Clear @flags in @worker->flags and adjust nr_running accordingly. |
d302f017 | 763 | * |
cb444766 TH |
764 | * CONTEXT: |
765 | * spin_lock_irq(gcwq->lock) | |
d302f017 TH |
766 | */ |
767 | static inline void worker_clr_flags(struct worker *worker, unsigned int flags) | |
768 | { | |
e22bee78 TH |
769 | struct global_cwq *gcwq = worker->gcwq; |
770 | unsigned int oflags = worker->flags; | |
771 | ||
cb444766 TH |
772 | WARN_ON_ONCE(worker->task != current); |
773 | ||
d302f017 | 774 | worker->flags &= ~flags; |
e22bee78 TH |
775 | |
776 | /* if transitioning out of NOT_RUNNING, increment nr_running */ | |
777 | if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) | |
778 | if (!(worker->flags & WORKER_NOT_RUNNING)) | |
779 | atomic_inc(get_gcwq_nr_running(gcwq->cpu)); | |
d302f017 TH |
780 | } |
781 | ||
c8e55f36 TH |
782 | /** |
783 | * busy_worker_head - return the busy hash head for a work | |
784 | * @gcwq: gcwq of interest | |
785 | * @work: work to be hashed | |
786 | * | |
787 | * Return hash head of @gcwq for @work. | |
788 | * | |
789 | * CONTEXT: | |
790 | * spin_lock_irq(gcwq->lock). | |
791 | * | |
792 | * RETURNS: | |
793 | * Pointer to the hash head. | |
794 | */ | |
795 | static struct hlist_head *busy_worker_head(struct global_cwq *gcwq, | |
796 | struct work_struct *work) | |
797 | { | |
798 | const int base_shift = ilog2(sizeof(struct work_struct)); | |
799 | unsigned long v = (unsigned long)work; | |
800 | ||
801 | /* simple shift and fold hash, do we need something better? */ | |
802 | v >>= base_shift; | |
803 | v += v >> BUSY_WORKER_HASH_ORDER; | |
804 | v &= BUSY_WORKER_HASH_MASK; | |
805 | ||
806 | return &gcwq->busy_hash[v]; | |
807 | } | |
808 | ||
8cca0eea TH |
809 | /** |
810 | * __find_worker_executing_work - find worker which is executing a work | |
811 | * @gcwq: gcwq of interest | |
812 | * @bwh: hash head as returned by busy_worker_head() | |
813 | * @work: work to find worker for | |
814 | * | |
815 | * Find a worker which is executing @work on @gcwq. @bwh should be | |
816 | * the hash head obtained by calling busy_worker_head() with the same | |
817 | * work. | |
818 | * | |
819 | * CONTEXT: | |
820 | * spin_lock_irq(gcwq->lock). | |
821 | * | |
822 | * RETURNS: | |
823 | * Pointer to worker which is executing @work if found, NULL | |
824 | * otherwise. | |
825 | */ | |
826 | static struct worker *__find_worker_executing_work(struct global_cwq *gcwq, | |
827 | struct hlist_head *bwh, | |
828 | struct work_struct *work) | |
829 | { | |
830 | struct worker *worker; | |
831 | struct hlist_node *tmp; | |
832 | ||
833 | hlist_for_each_entry(worker, tmp, bwh, hentry) | |
834 | if (worker->current_work == work) | |
835 | return worker; | |
836 | return NULL; | |
837 | } | |
838 | ||
839 | /** | |
840 | * find_worker_executing_work - find worker which is executing a work | |
841 | * @gcwq: gcwq of interest | |
842 | * @work: work to find worker for | |
843 | * | |
844 | * Find a worker which is executing @work on @gcwq. This function is | |
845 | * identical to __find_worker_executing_work() except that this | |
846 | * function calculates @bwh itself. | |
847 | * | |
848 | * CONTEXT: | |
849 | * spin_lock_irq(gcwq->lock). | |
850 | * | |
851 | * RETURNS: | |
852 | * Pointer to worker which is executing @work if found, NULL | |
853 | * otherwise. | |
4d707b9f | 854 | */ |
8cca0eea TH |
855 | static struct worker *find_worker_executing_work(struct global_cwq *gcwq, |
856 | struct work_struct *work) | |
4d707b9f | 857 | { |
8cca0eea TH |
858 | return __find_worker_executing_work(gcwq, busy_worker_head(gcwq, work), |
859 | work); | |
4d707b9f ON |
860 | } |
861 | ||
649027d7 TH |
862 | /** |
863 | * gcwq_determine_ins_pos - find insertion position | |
864 | * @gcwq: gcwq of interest | |
865 | * @cwq: cwq a work is being queued for | |
866 | * | |
867 | * A work for @cwq is about to be queued on @gcwq, determine insertion | |
868 | * position for the work. If @cwq is for HIGHPRI wq, the work is | |
869 | * queued at the head of the queue but in FIFO order with respect to | |
870 | * other HIGHPRI works; otherwise, at the end of the queue. This | |
871 | * function also sets GCWQ_HIGHPRI_PENDING flag to hint @gcwq that | |
872 | * there are HIGHPRI works pending. | |
873 | * | |
874 | * CONTEXT: | |
875 | * spin_lock_irq(gcwq->lock). | |
876 | * | |
877 | * RETURNS: | |
878 | * Pointer to inserstion position. | |
879 | */ | |
880 | static inline struct list_head *gcwq_determine_ins_pos(struct global_cwq *gcwq, | |
881 | struct cpu_workqueue_struct *cwq) | |
365970a1 | 882 | { |
649027d7 TH |
883 | struct work_struct *twork; |
884 | ||
885 | if (likely(!(cwq->wq->flags & WQ_HIGHPRI))) | |
886 | return &gcwq->worklist; | |
887 | ||
888 | list_for_each_entry(twork, &gcwq->worklist, entry) { | |
889 | struct cpu_workqueue_struct *tcwq = get_work_cwq(twork); | |
890 | ||
891 | if (!(tcwq->wq->flags & WQ_HIGHPRI)) | |
892 | break; | |
893 | } | |
894 | ||
895 | gcwq->flags |= GCWQ_HIGHPRI_PENDING; | |
896 | return &twork->entry; | |
365970a1 DH |
897 | } |
898 | ||
4690c4ab | 899 | /** |
7e11629d | 900 | * insert_work - insert a work into gcwq |
4690c4ab TH |
901 | * @cwq: cwq @work belongs to |
902 | * @work: work to insert | |
903 | * @head: insertion point | |
904 | * @extra_flags: extra WORK_STRUCT_* flags to set | |
905 | * | |
7e11629d TH |
906 | * Insert @work which belongs to @cwq into @gcwq after @head. |
907 | * @extra_flags is or'd to work_struct flags. | |
4690c4ab TH |
908 | * |
909 | * CONTEXT: | |
8b03ae3c | 910 | * spin_lock_irq(gcwq->lock). |
4690c4ab | 911 | */ |
b89deed3 | 912 | static void insert_work(struct cpu_workqueue_struct *cwq, |
4690c4ab TH |
913 | struct work_struct *work, struct list_head *head, |
914 | unsigned int extra_flags) | |
b89deed3 | 915 | { |
e22bee78 TH |
916 | struct global_cwq *gcwq = cwq->gcwq; |
917 | ||
4690c4ab | 918 | /* we own @work, set data and link */ |
7a22ad75 | 919 | set_work_cwq(work, cwq, extra_flags); |
e1d8aa9f | 920 | |
6e84d644 ON |
921 | /* |
922 | * Ensure that we get the right work->data if we see the | |
923 | * result of list_add() below, see try_to_grab_pending(). | |
924 | */ | |
925 | smp_wmb(); | |
4690c4ab | 926 | |
1a4d9b0a | 927 | list_add_tail(&work->entry, head); |
e22bee78 TH |
928 | |
929 | /* | |
930 | * Ensure either worker_sched_deactivated() sees the above | |
931 | * list_add_tail() or we see zero nr_running to avoid workers | |
932 | * lying around lazily while there are works to be processed. | |
933 | */ | |
934 | smp_mb(); | |
935 | ||
649027d7 | 936 | if (__need_more_worker(gcwq)) |
e22bee78 | 937 | wake_up_worker(gcwq); |
b89deed3 ON |
938 | } |
939 | ||
4690c4ab | 940 | static void __queue_work(unsigned int cpu, struct workqueue_struct *wq, |
1da177e4 LT |
941 | struct work_struct *work) |
942 | { | |
502ca9d8 TH |
943 | struct global_cwq *gcwq; |
944 | struct cpu_workqueue_struct *cwq; | |
1e19ffc6 | 945 | struct list_head *worklist; |
1da177e4 LT |
946 | unsigned long flags; |
947 | ||
dc186ad7 | 948 | debug_work_activate(work); |
1e19ffc6 | 949 | |
c7fc77f7 TH |
950 | /* determine gcwq to use */ |
951 | if (!(wq->flags & WQ_UNBOUND)) { | |
18aa9eff TH |
952 | struct global_cwq *last_gcwq; |
953 | ||
c7fc77f7 TH |
954 | if (unlikely(cpu == WORK_CPU_UNBOUND)) |
955 | cpu = raw_smp_processor_id(); | |
956 | ||
18aa9eff TH |
957 | /* |
958 | * It's multi cpu. If @wq is non-reentrant and @work | |
959 | * was previously on a different cpu, it might still | |
960 | * be running there, in which case the work needs to | |
961 | * be queued on that cpu to guarantee non-reentrance. | |
962 | */ | |
502ca9d8 | 963 | gcwq = get_gcwq(cpu); |
18aa9eff TH |
964 | if (wq->flags & WQ_NON_REENTRANT && |
965 | (last_gcwq = get_work_gcwq(work)) && last_gcwq != gcwq) { | |
966 | struct worker *worker; | |
967 | ||
968 | spin_lock_irqsave(&last_gcwq->lock, flags); | |
969 | ||
970 | worker = find_worker_executing_work(last_gcwq, work); | |
971 | ||
972 | if (worker && worker->current_cwq->wq == wq) | |
973 | gcwq = last_gcwq; | |
974 | else { | |
975 | /* meh... not running there, queue here */ | |
976 | spin_unlock_irqrestore(&last_gcwq->lock, flags); | |
977 | spin_lock_irqsave(&gcwq->lock, flags); | |
978 | } | |
979 | } else | |
980 | spin_lock_irqsave(&gcwq->lock, flags); | |
f3421797 TH |
981 | } else { |
982 | gcwq = get_gcwq(WORK_CPU_UNBOUND); | |
983 | spin_lock_irqsave(&gcwq->lock, flags); | |
502ca9d8 TH |
984 | } |
985 | ||
986 | /* gcwq determined, get cwq and queue */ | |
987 | cwq = get_cwq(gcwq->cpu, wq); | |
988 | ||
4690c4ab | 989 | BUG_ON(!list_empty(&work->entry)); |
1e19ffc6 | 990 | |
73f53c4a | 991 | cwq->nr_in_flight[cwq->work_color]++; |
1e19ffc6 TH |
992 | |
993 | if (likely(cwq->nr_active < cwq->max_active)) { | |
994 | cwq->nr_active++; | |
649027d7 | 995 | worklist = gcwq_determine_ins_pos(gcwq, cwq); |
1e19ffc6 TH |
996 | } else |
997 | worklist = &cwq->delayed_works; | |
998 | ||
999 | insert_work(cwq, work, worklist, work_color_to_flags(cwq->work_color)); | |
1000 | ||
8b03ae3c | 1001 | spin_unlock_irqrestore(&gcwq->lock, flags); |
1da177e4 LT |
1002 | } |
1003 | ||
0fcb78c2 REB |
1004 | /** |
1005 | * queue_work - queue work on a workqueue | |
1006 | * @wq: workqueue to use | |
1007 | * @work: work to queue | |
1008 | * | |
057647fc | 1009 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
1da177e4 | 1010 | * |
00dfcaf7 ON |
1011 | * We queue the work to the CPU on which it was submitted, but if the CPU dies |
1012 | * it can be processed by another CPU. | |
1da177e4 | 1013 | */ |
7ad5b3a5 | 1014 | int queue_work(struct workqueue_struct *wq, struct work_struct *work) |
1da177e4 | 1015 | { |
ef1ca236 ON |
1016 | int ret; |
1017 | ||
1018 | ret = queue_work_on(get_cpu(), wq, work); | |
1019 | put_cpu(); | |
1020 | ||
1da177e4 LT |
1021 | return ret; |
1022 | } | |
ae90dd5d | 1023 | EXPORT_SYMBOL_GPL(queue_work); |
1da177e4 | 1024 | |
c1a220e7 ZR |
1025 | /** |
1026 | * queue_work_on - queue work on specific cpu | |
1027 | * @cpu: CPU number to execute work on | |
1028 | * @wq: workqueue to use | |
1029 | * @work: work to queue | |
1030 | * | |
1031 | * Returns 0 if @work was already on a queue, non-zero otherwise. | |
1032 | * | |
1033 | * We queue the work to a specific CPU, the caller must ensure it | |
1034 | * can't go away. | |
1035 | */ | |
1036 | int | |
1037 | queue_work_on(int cpu, struct workqueue_struct *wq, struct work_struct *work) | |
1038 | { | |
1039 | int ret = 0; | |
1040 | ||
22df02bb | 1041 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
4690c4ab | 1042 | __queue_work(cpu, wq, work); |
c1a220e7 ZR |
1043 | ret = 1; |
1044 | } | |
1045 | return ret; | |
1046 | } | |
1047 | EXPORT_SYMBOL_GPL(queue_work_on); | |
1048 | ||
6d141c3f | 1049 | static void delayed_work_timer_fn(unsigned long __data) |
1da177e4 | 1050 | { |
52bad64d | 1051 | struct delayed_work *dwork = (struct delayed_work *)__data; |
7a22ad75 | 1052 | struct cpu_workqueue_struct *cwq = get_work_cwq(&dwork->work); |
1da177e4 | 1053 | |
4690c4ab | 1054 | __queue_work(smp_processor_id(), cwq->wq, &dwork->work); |
1da177e4 LT |
1055 | } |
1056 | ||
0fcb78c2 REB |
1057 | /** |
1058 | * queue_delayed_work - queue work on a workqueue after delay | |
1059 | * @wq: workqueue to use | |
af9997e4 | 1060 | * @dwork: delayable work to queue |
0fcb78c2 REB |
1061 | * @delay: number of jiffies to wait before queueing |
1062 | * | |
057647fc | 1063 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
0fcb78c2 | 1064 | */ |
7ad5b3a5 | 1065 | int queue_delayed_work(struct workqueue_struct *wq, |
52bad64d | 1066 | struct delayed_work *dwork, unsigned long delay) |
1da177e4 | 1067 | { |
52bad64d | 1068 | if (delay == 0) |
63bc0362 | 1069 | return queue_work(wq, &dwork->work); |
1da177e4 | 1070 | |
63bc0362 | 1071 | return queue_delayed_work_on(-1, wq, dwork, delay); |
1da177e4 | 1072 | } |
ae90dd5d | 1073 | EXPORT_SYMBOL_GPL(queue_delayed_work); |
1da177e4 | 1074 | |
0fcb78c2 REB |
1075 | /** |
1076 | * queue_delayed_work_on - queue work on specific CPU after delay | |
1077 | * @cpu: CPU number to execute work on | |
1078 | * @wq: workqueue to use | |
af9997e4 | 1079 | * @dwork: work to queue |
0fcb78c2 REB |
1080 | * @delay: number of jiffies to wait before queueing |
1081 | * | |
057647fc | 1082 | * Returns 0 if @work was already on a queue, non-zero otherwise. |
0fcb78c2 | 1083 | */ |
7a6bc1cd | 1084 | int queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
52bad64d | 1085 | struct delayed_work *dwork, unsigned long delay) |
7a6bc1cd VP |
1086 | { |
1087 | int ret = 0; | |
52bad64d DH |
1088 | struct timer_list *timer = &dwork->timer; |
1089 | struct work_struct *work = &dwork->work; | |
7a6bc1cd | 1090 | |
22df02bb | 1091 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
c7fc77f7 | 1092 | unsigned int lcpu; |
7a22ad75 | 1093 | |
7a6bc1cd VP |
1094 | BUG_ON(timer_pending(timer)); |
1095 | BUG_ON(!list_empty(&work->entry)); | |
1096 | ||
8a3e77cc AL |
1097 | timer_stats_timer_set_start_info(&dwork->timer); |
1098 | ||
7a22ad75 TH |
1099 | /* |
1100 | * This stores cwq for the moment, for the timer_fn. | |
1101 | * Note that the work's gcwq is preserved to allow | |
1102 | * reentrance detection for delayed works. | |
1103 | */ | |
c7fc77f7 TH |
1104 | if (!(wq->flags & WQ_UNBOUND)) { |
1105 | struct global_cwq *gcwq = get_work_gcwq(work); | |
1106 | ||
1107 | if (gcwq && gcwq->cpu != WORK_CPU_UNBOUND) | |
1108 | lcpu = gcwq->cpu; | |
1109 | else | |
1110 | lcpu = raw_smp_processor_id(); | |
1111 | } else | |
1112 | lcpu = WORK_CPU_UNBOUND; | |
1113 | ||
7a22ad75 | 1114 | set_work_cwq(work, get_cwq(lcpu, wq), 0); |
c7fc77f7 | 1115 | |
7a6bc1cd | 1116 | timer->expires = jiffies + delay; |
52bad64d | 1117 | timer->data = (unsigned long)dwork; |
7a6bc1cd | 1118 | timer->function = delayed_work_timer_fn; |
63bc0362 ON |
1119 | |
1120 | if (unlikely(cpu >= 0)) | |
1121 | add_timer_on(timer, cpu); | |
1122 | else | |
1123 | add_timer(timer); | |
7a6bc1cd VP |
1124 | ret = 1; |
1125 | } | |
1126 | return ret; | |
1127 | } | |
ae90dd5d | 1128 | EXPORT_SYMBOL_GPL(queue_delayed_work_on); |
1da177e4 | 1129 | |
c8e55f36 TH |
1130 | /** |
1131 | * worker_enter_idle - enter idle state | |
1132 | * @worker: worker which is entering idle state | |
1133 | * | |
1134 | * @worker is entering idle state. Update stats and idle timer if | |
1135 | * necessary. | |
1136 | * | |
1137 | * LOCKING: | |
1138 | * spin_lock_irq(gcwq->lock). | |
1139 | */ | |
1140 | static void worker_enter_idle(struct worker *worker) | |
1da177e4 | 1141 | { |
c8e55f36 TH |
1142 | struct global_cwq *gcwq = worker->gcwq; |
1143 | ||
1144 | BUG_ON(worker->flags & WORKER_IDLE); | |
1145 | BUG_ON(!list_empty(&worker->entry) && | |
1146 | (worker->hentry.next || worker->hentry.pprev)); | |
1147 | ||
cb444766 TH |
1148 | /* can't use worker_set_flags(), also called from start_worker() */ |
1149 | worker->flags |= WORKER_IDLE; | |
c8e55f36 | 1150 | gcwq->nr_idle++; |
e22bee78 | 1151 | worker->last_active = jiffies; |
c8e55f36 TH |
1152 | |
1153 | /* idle_list is LIFO */ | |
1154 | list_add(&worker->entry, &gcwq->idle_list); | |
db7bccf4 | 1155 | |
e22bee78 TH |
1156 | if (likely(!(worker->flags & WORKER_ROGUE))) { |
1157 | if (too_many_workers(gcwq) && !timer_pending(&gcwq->idle_timer)) | |
1158 | mod_timer(&gcwq->idle_timer, | |
1159 | jiffies + IDLE_WORKER_TIMEOUT); | |
1160 | } else | |
db7bccf4 | 1161 | wake_up_all(&gcwq->trustee_wait); |
cb444766 TH |
1162 | |
1163 | /* sanity check nr_running */ | |
1164 | WARN_ON_ONCE(gcwq->nr_workers == gcwq->nr_idle && | |
1165 | atomic_read(get_gcwq_nr_running(gcwq->cpu))); | |
c8e55f36 TH |
1166 | } |
1167 | ||
1168 | /** | |
1169 | * worker_leave_idle - leave idle state | |
1170 | * @worker: worker which is leaving idle state | |
1171 | * | |
1172 | * @worker is leaving idle state. Update stats. | |
1173 | * | |
1174 | * LOCKING: | |
1175 | * spin_lock_irq(gcwq->lock). | |
1176 | */ | |
1177 | static void worker_leave_idle(struct worker *worker) | |
1178 | { | |
1179 | struct global_cwq *gcwq = worker->gcwq; | |
1180 | ||
1181 | BUG_ON(!(worker->flags & WORKER_IDLE)); | |
d302f017 | 1182 | worker_clr_flags(worker, WORKER_IDLE); |
c8e55f36 TH |
1183 | gcwq->nr_idle--; |
1184 | list_del_init(&worker->entry); | |
1185 | } | |
1186 | ||
e22bee78 TH |
1187 | /** |
1188 | * worker_maybe_bind_and_lock - bind worker to its cpu if possible and lock gcwq | |
1189 | * @worker: self | |
1190 | * | |
1191 | * Works which are scheduled while the cpu is online must at least be | |
1192 | * scheduled to a worker which is bound to the cpu so that if they are | |
1193 | * flushed from cpu callbacks while cpu is going down, they are | |
1194 | * guaranteed to execute on the cpu. | |
1195 | * | |
1196 | * This function is to be used by rogue workers and rescuers to bind | |
1197 | * themselves to the target cpu and may race with cpu going down or | |
1198 | * coming online. kthread_bind() can't be used because it may put the | |
1199 | * worker to already dead cpu and set_cpus_allowed_ptr() can't be used | |
1200 | * verbatim as it's best effort and blocking and gcwq may be | |
1201 | * [dis]associated in the meantime. | |
1202 | * | |
1203 | * This function tries set_cpus_allowed() and locks gcwq and verifies | |
1204 | * the binding against GCWQ_DISASSOCIATED which is set during | |
1205 | * CPU_DYING and cleared during CPU_ONLINE, so if the worker enters | |
1206 | * idle state or fetches works without dropping lock, it can guarantee | |
1207 | * the scheduling requirement described in the first paragraph. | |
1208 | * | |
1209 | * CONTEXT: | |
1210 | * Might sleep. Called without any lock but returns with gcwq->lock | |
1211 | * held. | |
1212 | * | |
1213 | * RETURNS: | |
1214 | * %true if the associated gcwq is online (@worker is successfully | |
1215 | * bound), %false if offline. | |
1216 | */ | |
1217 | static bool worker_maybe_bind_and_lock(struct worker *worker) | |
1218 | { | |
1219 | struct global_cwq *gcwq = worker->gcwq; | |
1220 | struct task_struct *task = worker->task; | |
1221 | ||
1222 | while (true) { | |
4e6045f1 | 1223 | /* |
e22bee78 TH |
1224 | * The following call may fail, succeed or succeed |
1225 | * without actually migrating the task to the cpu if | |
1226 | * it races with cpu hotunplug operation. Verify | |
1227 | * against GCWQ_DISASSOCIATED. | |
4e6045f1 | 1228 | */ |
f3421797 TH |
1229 | if (!(gcwq->flags & GCWQ_DISASSOCIATED)) |
1230 | set_cpus_allowed_ptr(task, get_cpu_mask(gcwq->cpu)); | |
e22bee78 TH |
1231 | |
1232 | spin_lock_irq(&gcwq->lock); | |
1233 | if (gcwq->flags & GCWQ_DISASSOCIATED) | |
1234 | return false; | |
1235 | if (task_cpu(task) == gcwq->cpu && | |
1236 | cpumask_equal(¤t->cpus_allowed, | |
1237 | get_cpu_mask(gcwq->cpu))) | |
1238 | return true; | |
1239 | spin_unlock_irq(&gcwq->lock); | |
1240 | ||
1241 | /* CPU has come up inbetween, retry migration */ | |
1242 | cpu_relax(); | |
1243 | } | |
1244 | } | |
1245 | ||
1246 | /* | |
1247 | * Function for worker->rebind_work used to rebind rogue busy workers | |
1248 | * to the associated cpu which is coming back online. This is | |
1249 | * scheduled by cpu up but can race with other cpu hotplug operations | |
1250 | * and may be executed twice without intervening cpu down. | |
1251 | */ | |
1252 | static void worker_rebind_fn(struct work_struct *work) | |
1253 | { | |
1254 | struct worker *worker = container_of(work, struct worker, rebind_work); | |
1255 | struct global_cwq *gcwq = worker->gcwq; | |
1256 | ||
1257 | if (worker_maybe_bind_and_lock(worker)) | |
1258 | worker_clr_flags(worker, WORKER_REBIND); | |
1259 | ||
1260 | spin_unlock_irq(&gcwq->lock); | |
1261 | } | |
1262 | ||
c34056a3 TH |
1263 | static struct worker *alloc_worker(void) |
1264 | { | |
1265 | struct worker *worker; | |
1266 | ||
1267 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); | |
c8e55f36 TH |
1268 | if (worker) { |
1269 | INIT_LIST_HEAD(&worker->entry); | |
affee4b2 | 1270 | INIT_LIST_HEAD(&worker->scheduled); |
e22bee78 TH |
1271 | INIT_WORK(&worker->rebind_work, worker_rebind_fn); |
1272 | /* on creation a worker is in !idle && prep state */ | |
1273 | worker->flags = WORKER_PREP; | |
c8e55f36 | 1274 | } |
c34056a3 TH |
1275 | return worker; |
1276 | } | |
1277 | ||
1278 | /** | |
1279 | * create_worker - create a new workqueue worker | |
7e11629d | 1280 | * @gcwq: gcwq the new worker will belong to |
c34056a3 TH |
1281 | * @bind: whether to set affinity to @cpu or not |
1282 | * | |
7e11629d | 1283 | * Create a new worker which is bound to @gcwq. The returned worker |
c34056a3 TH |
1284 | * can be started by calling start_worker() or destroyed using |
1285 | * destroy_worker(). | |
1286 | * | |
1287 | * CONTEXT: | |
1288 | * Might sleep. Does GFP_KERNEL allocations. | |
1289 | * | |
1290 | * RETURNS: | |
1291 | * Pointer to the newly created worker. | |
1292 | */ | |
7e11629d | 1293 | static struct worker *create_worker(struct global_cwq *gcwq, bool bind) |
c34056a3 | 1294 | { |
f3421797 | 1295 | bool on_unbound_cpu = gcwq->cpu == WORK_CPU_UNBOUND; |
c34056a3 | 1296 | struct worker *worker = NULL; |
f3421797 | 1297 | int id = -1; |
c34056a3 | 1298 | |
8b03ae3c TH |
1299 | spin_lock_irq(&gcwq->lock); |
1300 | while (ida_get_new(&gcwq->worker_ida, &id)) { | |
1301 | spin_unlock_irq(&gcwq->lock); | |
1302 | if (!ida_pre_get(&gcwq->worker_ida, GFP_KERNEL)) | |
c34056a3 | 1303 | goto fail; |
8b03ae3c | 1304 | spin_lock_irq(&gcwq->lock); |
c34056a3 | 1305 | } |
8b03ae3c | 1306 | spin_unlock_irq(&gcwq->lock); |
c34056a3 TH |
1307 | |
1308 | worker = alloc_worker(); | |
1309 | if (!worker) | |
1310 | goto fail; | |
1311 | ||
8b03ae3c | 1312 | worker->gcwq = gcwq; |
c34056a3 TH |
1313 | worker->id = id; |
1314 | ||
f3421797 TH |
1315 | if (!on_unbound_cpu) |
1316 | worker->task = kthread_create(worker_thread, worker, | |
1317 | "kworker/%u:%d", gcwq->cpu, id); | |
1318 | else | |
1319 | worker->task = kthread_create(worker_thread, worker, | |
1320 | "kworker/u:%d", id); | |
c34056a3 TH |
1321 | if (IS_ERR(worker->task)) |
1322 | goto fail; | |
1323 | ||
db7bccf4 TH |
1324 | /* |
1325 | * A rogue worker will become a regular one if CPU comes | |
1326 | * online later on. Make sure every worker has | |
1327 | * PF_THREAD_BOUND set. | |
1328 | */ | |
f3421797 | 1329 | if (bind && !on_unbound_cpu) |
8b03ae3c | 1330 | kthread_bind(worker->task, gcwq->cpu); |
f3421797 | 1331 | else { |
db7bccf4 | 1332 | worker->task->flags |= PF_THREAD_BOUND; |
f3421797 TH |
1333 | if (on_unbound_cpu) |
1334 | worker->flags |= WORKER_UNBOUND; | |
1335 | } | |
c34056a3 TH |
1336 | |
1337 | return worker; | |
1338 | fail: | |
1339 | if (id >= 0) { | |
8b03ae3c TH |
1340 | spin_lock_irq(&gcwq->lock); |
1341 | ida_remove(&gcwq->worker_ida, id); | |
1342 | spin_unlock_irq(&gcwq->lock); | |
c34056a3 TH |
1343 | } |
1344 | kfree(worker); | |
1345 | return NULL; | |
1346 | } | |
1347 | ||
1348 | /** | |
1349 | * start_worker - start a newly created worker | |
1350 | * @worker: worker to start | |
1351 | * | |
c8e55f36 | 1352 | * Make the gcwq aware of @worker and start it. |
c34056a3 TH |
1353 | * |
1354 | * CONTEXT: | |
8b03ae3c | 1355 | * spin_lock_irq(gcwq->lock). |
c34056a3 TH |
1356 | */ |
1357 | static void start_worker(struct worker *worker) | |
1358 | { | |
cb444766 | 1359 | worker->flags |= WORKER_STARTED; |
c8e55f36 TH |
1360 | worker->gcwq->nr_workers++; |
1361 | worker_enter_idle(worker); | |
c34056a3 TH |
1362 | wake_up_process(worker->task); |
1363 | } | |
1364 | ||
1365 | /** | |
1366 | * destroy_worker - destroy a workqueue worker | |
1367 | * @worker: worker to be destroyed | |
1368 | * | |
c8e55f36 TH |
1369 | * Destroy @worker and adjust @gcwq stats accordingly. |
1370 | * | |
1371 | * CONTEXT: | |
1372 | * spin_lock_irq(gcwq->lock) which is released and regrabbed. | |
c34056a3 TH |
1373 | */ |
1374 | static void destroy_worker(struct worker *worker) | |
1375 | { | |
8b03ae3c | 1376 | struct global_cwq *gcwq = worker->gcwq; |
c34056a3 TH |
1377 | int id = worker->id; |
1378 | ||
1379 | /* sanity check frenzy */ | |
1380 | BUG_ON(worker->current_work); | |
affee4b2 | 1381 | BUG_ON(!list_empty(&worker->scheduled)); |
c34056a3 | 1382 | |
c8e55f36 TH |
1383 | if (worker->flags & WORKER_STARTED) |
1384 | gcwq->nr_workers--; | |
1385 | if (worker->flags & WORKER_IDLE) | |
1386 | gcwq->nr_idle--; | |
1387 | ||
1388 | list_del_init(&worker->entry); | |
cb444766 | 1389 | worker->flags |= WORKER_DIE; |
c8e55f36 TH |
1390 | |
1391 | spin_unlock_irq(&gcwq->lock); | |
1392 | ||
c34056a3 TH |
1393 | kthread_stop(worker->task); |
1394 | kfree(worker); | |
1395 | ||
8b03ae3c TH |
1396 | spin_lock_irq(&gcwq->lock); |
1397 | ida_remove(&gcwq->worker_ida, id); | |
c34056a3 TH |
1398 | } |
1399 | ||
e22bee78 TH |
1400 | static void idle_worker_timeout(unsigned long __gcwq) |
1401 | { | |
1402 | struct global_cwq *gcwq = (void *)__gcwq; | |
1403 | ||
1404 | spin_lock_irq(&gcwq->lock); | |
1405 | ||
1406 | if (too_many_workers(gcwq)) { | |
1407 | struct worker *worker; | |
1408 | unsigned long expires; | |
1409 | ||
1410 | /* idle_list is kept in LIFO order, check the last one */ | |
1411 | worker = list_entry(gcwq->idle_list.prev, struct worker, entry); | |
1412 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; | |
1413 | ||
1414 | if (time_before(jiffies, expires)) | |
1415 | mod_timer(&gcwq->idle_timer, expires); | |
1416 | else { | |
1417 | /* it's been idle for too long, wake up manager */ | |
1418 | gcwq->flags |= GCWQ_MANAGE_WORKERS; | |
1419 | wake_up_worker(gcwq); | |
d5abe669 | 1420 | } |
e22bee78 TH |
1421 | } |
1422 | ||
1423 | spin_unlock_irq(&gcwq->lock); | |
1424 | } | |
d5abe669 | 1425 | |
e22bee78 TH |
1426 | static bool send_mayday(struct work_struct *work) |
1427 | { | |
1428 | struct cpu_workqueue_struct *cwq = get_work_cwq(work); | |
1429 | struct workqueue_struct *wq = cwq->wq; | |
f3421797 | 1430 | unsigned int cpu; |
e22bee78 TH |
1431 | |
1432 | if (!(wq->flags & WQ_RESCUER)) | |
1433 | return false; | |
1434 | ||
1435 | /* mayday mayday mayday */ | |
f3421797 TH |
1436 | cpu = cwq->gcwq->cpu; |
1437 | /* WORK_CPU_UNBOUND can't be set in cpumask, use cpu 0 instead */ | |
1438 | if (cpu == WORK_CPU_UNBOUND) | |
1439 | cpu = 0; | |
f2e005aa | 1440 | if (!mayday_test_and_set_cpu(cpu, wq->mayday_mask)) |
e22bee78 TH |
1441 | wake_up_process(wq->rescuer->task); |
1442 | return true; | |
1443 | } | |
1444 | ||
1445 | static void gcwq_mayday_timeout(unsigned long __gcwq) | |
1446 | { | |
1447 | struct global_cwq *gcwq = (void *)__gcwq; | |
1448 | struct work_struct *work; | |
1449 | ||
1450 | spin_lock_irq(&gcwq->lock); | |
1451 | ||
1452 | if (need_to_create_worker(gcwq)) { | |
1453 | /* | |
1454 | * We've been trying to create a new worker but | |
1455 | * haven't been successful. We might be hitting an | |
1456 | * allocation deadlock. Send distress signals to | |
1457 | * rescuers. | |
1458 | */ | |
1459 | list_for_each_entry(work, &gcwq->worklist, entry) | |
1460 | send_mayday(work); | |
1da177e4 | 1461 | } |
e22bee78 TH |
1462 | |
1463 | spin_unlock_irq(&gcwq->lock); | |
1464 | ||
1465 | mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INTERVAL); | |
1da177e4 LT |
1466 | } |
1467 | ||
e22bee78 TH |
1468 | /** |
1469 | * maybe_create_worker - create a new worker if necessary | |
1470 | * @gcwq: gcwq to create a new worker for | |
1471 | * | |
1472 | * Create a new worker for @gcwq if necessary. @gcwq is guaranteed to | |
1473 | * have at least one idle worker on return from this function. If | |
1474 | * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is | |
1475 | * sent to all rescuers with works scheduled on @gcwq to resolve | |
1476 | * possible allocation deadlock. | |
1477 | * | |
1478 | * On return, need_to_create_worker() is guaranteed to be false and | |
1479 | * may_start_working() true. | |
1480 | * | |
1481 | * LOCKING: | |
1482 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed | |
1483 | * multiple times. Does GFP_KERNEL allocations. Called only from | |
1484 | * manager. | |
1485 | * | |
1486 | * RETURNS: | |
1487 | * false if no action was taken and gcwq->lock stayed locked, true | |
1488 | * otherwise. | |
1489 | */ | |
1490 | static bool maybe_create_worker(struct global_cwq *gcwq) | |
1da177e4 | 1491 | { |
e22bee78 TH |
1492 | if (!need_to_create_worker(gcwq)) |
1493 | return false; | |
1494 | restart: | |
9f9c2364 TH |
1495 | spin_unlock_irq(&gcwq->lock); |
1496 | ||
e22bee78 TH |
1497 | /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ |
1498 | mod_timer(&gcwq->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); | |
1499 | ||
1500 | while (true) { | |
1501 | struct worker *worker; | |
1502 | ||
e22bee78 TH |
1503 | worker = create_worker(gcwq, true); |
1504 | if (worker) { | |
1505 | del_timer_sync(&gcwq->mayday_timer); | |
1506 | spin_lock_irq(&gcwq->lock); | |
1507 | start_worker(worker); | |
1508 | BUG_ON(need_to_create_worker(gcwq)); | |
1509 | return true; | |
1510 | } | |
1511 | ||
1512 | if (!need_to_create_worker(gcwq)) | |
1513 | break; | |
1da177e4 | 1514 | |
e22bee78 TH |
1515 | __set_current_state(TASK_INTERRUPTIBLE); |
1516 | schedule_timeout(CREATE_COOLDOWN); | |
9f9c2364 | 1517 | |
e22bee78 TH |
1518 | if (!need_to_create_worker(gcwq)) |
1519 | break; | |
1520 | } | |
1521 | ||
e22bee78 TH |
1522 | del_timer_sync(&gcwq->mayday_timer); |
1523 | spin_lock_irq(&gcwq->lock); | |
1524 | if (need_to_create_worker(gcwq)) | |
1525 | goto restart; | |
1526 | return true; | |
1527 | } | |
1528 | ||
1529 | /** | |
1530 | * maybe_destroy_worker - destroy workers which have been idle for a while | |
1531 | * @gcwq: gcwq to destroy workers for | |
1532 | * | |
1533 | * Destroy @gcwq workers which have been idle for longer than | |
1534 | * IDLE_WORKER_TIMEOUT. | |
1535 | * | |
1536 | * LOCKING: | |
1537 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed | |
1538 | * multiple times. Called only from manager. | |
1539 | * | |
1540 | * RETURNS: | |
1541 | * false if no action was taken and gcwq->lock stayed locked, true | |
1542 | * otherwise. | |
1543 | */ | |
1544 | static bool maybe_destroy_workers(struct global_cwq *gcwq) | |
1545 | { | |
1546 | bool ret = false; | |
1da177e4 | 1547 | |
e22bee78 TH |
1548 | while (too_many_workers(gcwq)) { |
1549 | struct worker *worker; | |
1550 | unsigned long expires; | |
3af24433 | 1551 | |
e22bee78 TH |
1552 | worker = list_entry(gcwq->idle_list.prev, struct worker, entry); |
1553 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; | |
85f4186a | 1554 | |
e22bee78 TH |
1555 | if (time_before(jiffies, expires)) { |
1556 | mod_timer(&gcwq->idle_timer, expires); | |
3af24433 | 1557 | break; |
e22bee78 | 1558 | } |
1da177e4 | 1559 | |
e22bee78 TH |
1560 | destroy_worker(worker); |
1561 | ret = true; | |
1da177e4 | 1562 | } |
3af24433 | 1563 | |
e22bee78 TH |
1564 | return ret; |
1565 | } | |
1566 | ||
1567 | /** | |
1568 | * manage_workers - manage worker pool | |
1569 | * @worker: self | |
1570 | * | |
1571 | * Assume the manager role and manage gcwq worker pool @worker belongs | |
1572 | * to. At any given time, there can be only zero or one manager per | |
1573 | * gcwq. The exclusion is handled automatically by this function. | |
1574 | * | |
1575 | * The caller can safely start processing works on false return. On | |
1576 | * true return, it's guaranteed that need_to_create_worker() is false | |
1577 | * and may_start_working() is true. | |
1578 | * | |
1579 | * CONTEXT: | |
1580 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed | |
1581 | * multiple times. Does GFP_KERNEL allocations. | |
1582 | * | |
1583 | * RETURNS: | |
1584 | * false if no action was taken and gcwq->lock stayed locked, true if | |
1585 | * some action was taken. | |
1586 | */ | |
1587 | static bool manage_workers(struct worker *worker) | |
1588 | { | |
1589 | struct global_cwq *gcwq = worker->gcwq; | |
1590 | bool ret = false; | |
1591 | ||
1592 | if (gcwq->flags & GCWQ_MANAGING_WORKERS) | |
1593 | return ret; | |
1594 | ||
1595 | gcwq->flags &= ~GCWQ_MANAGE_WORKERS; | |
1596 | gcwq->flags |= GCWQ_MANAGING_WORKERS; | |
1597 | ||
1598 | /* | |
1599 | * Destroy and then create so that may_start_working() is true | |
1600 | * on return. | |
1601 | */ | |
1602 | ret |= maybe_destroy_workers(gcwq); | |
1603 | ret |= maybe_create_worker(gcwq); | |
1604 | ||
1605 | gcwq->flags &= ~GCWQ_MANAGING_WORKERS; | |
1606 | ||
1607 | /* | |
1608 | * The trustee might be waiting to take over the manager | |
1609 | * position, tell it we're done. | |
1610 | */ | |
1611 | if (unlikely(gcwq->trustee)) | |
1612 | wake_up_all(&gcwq->trustee_wait); | |
1613 | ||
1614 | return ret; | |
1615 | } | |
1616 | ||
affee4b2 TH |
1617 | /** |
1618 | * move_linked_works - move linked works to a list | |
1619 | * @work: start of series of works to be scheduled | |
1620 | * @head: target list to append @work to | |
1621 | * @nextp: out paramter for nested worklist walking | |
1622 | * | |
1623 | * Schedule linked works starting from @work to @head. Work series to | |
1624 | * be scheduled starts at @work and includes any consecutive work with | |
1625 | * WORK_STRUCT_LINKED set in its predecessor. | |
1626 | * | |
1627 | * If @nextp is not NULL, it's updated to point to the next work of | |
1628 | * the last scheduled work. This allows move_linked_works() to be | |
1629 | * nested inside outer list_for_each_entry_safe(). | |
1630 | * | |
1631 | * CONTEXT: | |
8b03ae3c | 1632 | * spin_lock_irq(gcwq->lock). |
affee4b2 TH |
1633 | */ |
1634 | static void move_linked_works(struct work_struct *work, struct list_head *head, | |
1635 | struct work_struct **nextp) | |
1636 | { | |
1637 | struct work_struct *n; | |
1638 | ||
1639 | /* | |
1640 | * Linked worklist will always end before the end of the list, | |
1641 | * use NULL for list head. | |
1642 | */ | |
1643 | list_for_each_entry_safe_from(work, n, NULL, entry) { | |
1644 | list_move_tail(&work->entry, head); | |
1645 | if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) | |
1646 | break; | |
1647 | } | |
1648 | ||
1649 | /* | |
1650 | * If we're already inside safe list traversal and have moved | |
1651 | * multiple works to the scheduled queue, the next position | |
1652 | * needs to be updated. | |
1653 | */ | |
1654 | if (nextp) | |
1655 | *nextp = n; | |
1656 | } | |
1657 | ||
1e19ffc6 TH |
1658 | static void cwq_activate_first_delayed(struct cpu_workqueue_struct *cwq) |
1659 | { | |
1660 | struct work_struct *work = list_first_entry(&cwq->delayed_works, | |
1661 | struct work_struct, entry); | |
649027d7 | 1662 | struct list_head *pos = gcwq_determine_ins_pos(cwq->gcwq, cwq); |
1e19ffc6 | 1663 | |
649027d7 | 1664 | move_linked_works(work, pos, NULL); |
1e19ffc6 TH |
1665 | cwq->nr_active++; |
1666 | } | |
1667 | ||
73f53c4a TH |
1668 | /** |
1669 | * cwq_dec_nr_in_flight - decrement cwq's nr_in_flight | |
1670 | * @cwq: cwq of interest | |
1671 | * @color: color of work which left the queue | |
1672 | * | |
1673 | * A work either has completed or is removed from pending queue, | |
1674 | * decrement nr_in_flight of its cwq and handle workqueue flushing. | |
1675 | * | |
1676 | * CONTEXT: | |
8b03ae3c | 1677 | * spin_lock_irq(gcwq->lock). |
73f53c4a TH |
1678 | */ |
1679 | static void cwq_dec_nr_in_flight(struct cpu_workqueue_struct *cwq, int color) | |
1680 | { | |
1681 | /* ignore uncolored works */ | |
1682 | if (color == WORK_NO_COLOR) | |
1683 | return; | |
1684 | ||
1685 | cwq->nr_in_flight[color]--; | |
1e19ffc6 TH |
1686 | cwq->nr_active--; |
1687 | ||
502ca9d8 TH |
1688 | if (!list_empty(&cwq->delayed_works)) { |
1689 | /* one down, submit a delayed one */ | |
1690 | if (cwq->nr_active < cwq->max_active) | |
1691 | cwq_activate_first_delayed(cwq); | |
502ca9d8 | 1692 | } |
73f53c4a TH |
1693 | |
1694 | /* is flush in progress and are we at the flushing tip? */ | |
1695 | if (likely(cwq->flush_color != color)) | |
1696 | return; | |
1697 | ||
1698 | /* are there still in-flight works? */ | |
1699 | if (cwq->nr_in_flight[color]) | |
1700 | return; | |
1701 | ||
1702 | /* this cwq is done, clear flush_color */ | |
1703 | cwq->flush_color = -1; | |
1704 | ||
1705 | /* | |
1706 | * If this was the last cwq, wake up the first flusher. It | |
1707 | * will handle the rest. | |
1708 | */ | |
1709 | if (atomic_dec_and_test(&cwq->wq->nr_cwqs_to_flush)) | |
1710 | complete(&cwq->wq->first_flusher->done); | |
1711 | } | |
1712 | ||
a62428c0 TH |
1713 | /** |
1714 | * process_one_work - process single work | |
c34056a3 | 1715 | * @worker: self |
a62428c0 TH |
1716 | * @work: work to process |
1717 | * | |
1718 | * Process @work. This function contains all the logics necessary to | |
1719 | * process a single work including synchronization against and | |
1720 | * interaction with other workers on the same cpu, queueing and | |
1721 | * flushing. As long as context requirement is met, any worker can | |
1722 | * call this function to process a work. | |
1723 | * | |
1724 | * CONTEXT: | |
8b03ae3c | 1725 | * spin_lock_irq(gcwq->lock) which is released and regrabbed. |
a62428c0 | 1726 | */ |
c34056a3 | 1727 | static void process_one_work(struct worker *worker, struct work_struct *work) |
a62428c0 | 1728 | { |
7e11629d | 1729 | struct cpu_workqueue_struct *cwq = get_work_cwq(work); |
8b03ae3c | 1730 | struct global_cwq *gcwq = cwq->gcwq; |
c8e55f36 | 1731 | struct hlist_head *bwh = busy_worker_head(gcwq, work); |
fb0e7beb | 1732 | bool cpu_intensive = cwq->wq->flags & WQ_CPU_INTENSIVE; |
a62428c0 | 1733 | work_func_t f = work->func; |
73f53c4a | 1734 | int work_color; |
7e11629d | 1735 | struct worker *collision; |
a62428c0 TH |
1736 | #ifdef CONFIG_LOCKDEP |
1737 | /* | |
1738 | * It is permissible to free the struct work_struct from | |
1739 | * inside the function that is called from it, this we need to | |
1740 | * take into account for lockdep too. To avoid bogus "held | |
1741 | * lock freed" warnings as well as problems when looking into | |
1742 | * work->lockdep_map, make a copy and use that here. | |
1743 | */ | |
1744 | struct lockdep_map lockdep_map = work->lockdep_map; | |
1745 | #endif | |
7e11629d TH |
1746 | /* |
1747 | * A single work shouldn't be executed concurrently by | |
1748 | * multiple workers on a single cpu. Check whether anyone is | |
1749 | * already processing the work. If so, defer the work to the | |
1750 | * currently executing one. | |
1751 | */ | |
1752 | collision = __find_worker_executing_work(gcwq, bwh, work); | |
1753 | if (unlikely(collision)) { | |
1754 | move_linked_works(work, &collision->scheduled, NULL); | |
1755 | return; | |
1756 | } | |
1757 | ||
a62428c0 | 1758 | /* claim and process */ |
a62428c0 | 1759 | debug_work_deactivate(work); |
c8e55f36 | 1760 | hlist_add_head(&worker->hentry, bwh); |
c34056a3 | 1761 | worker->current_work = work; |
8cca0eea | 1762 | worker->current_cwq = cwq; |
73f53c4a | 1763 | work_color = get_work_color(work); |
7a22ad75 | 1764 | |
7a22ad75 TH |
1765 | /* record the current cpu number in the work data and dequeue */ |
1766 | set_work_cpu(work, gcwq->cpu); | |
a62428c0 TH |
1767 | list_del_init(&work->entry); |
1768 | ||
649027d7 TH |
1769 | /* |
1770 | * If HIGHPRI_PENDING, check the next work, and, if HIGHPRI, | |
1771 | * wake up another worker; otherwise, clear HIGHPRI_PENDING. | |
1772 | */ | |
1773 | if (unlikely(gcwq->flags & GCWQ_HIGHPRI_PENDING)) { | |
1774 | struct work_struct *nwork = list_first_entry(&gcwq->worklist, | |
1775 | struct work_struct, entry); | |
1776 | ||
1777 | if (!list_empty(&gcwq->worklist) && | |
1778 | get_work_cwq(nwork)->wq->flags & WQ_HIGHPRI) | |
1779 | wake_up_worker(gcwq); | |
1780 | else | |
1781 | gcwq->flags &= ~GCWQ_HIGHPRI_PENDING; | |
1782 | } | |
1783 | ||
fb0e7beb TH |
1784 | /* |
1785 | * CPU intensive works don't participate in concurrency | |
1786 | * management. They're the scheduler's responsibility. | |
1787 | */ | |
1788 | if (unlikely(cpu_intensive)) | |
1789 | worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); | |
1790 | ||
8b03ae3c | 1791 | spin_unlock_irq(&gcwq->lock); |
a62428c0 | 1792 | |
a62428c0 TH |
1793 | work_clear_pending(work); |
1794 | lock_map_acquire(&cwq->wq->lockdep_map); | |
1795 | lock_map_acquire(&lockdep_map); | |
e36c886a | 1796 | trace_workqueue_execute_start(work); |
a62428c0 | 1797 | f(work); |
e36c886a AV |
1798 | /* |
1799 | * While we must be careful to not use "work" after this, the trace | |
1800 | * point will only record its address. | |
1801 | */ | |
1802 | trace_workqueue_execute_end(work); | |
a62428c0 TH |
1803 | lock_map_release(&lockdep_map); |
1804 | lock_map_release(&cwq->wq->lockdep_map); | |
1805 | ||
1806 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { | |
1807 | printk(KERN_ERR "BUG: workqueue leaked lock or atomic: " | |
1808 | "%s/0x%08x/%d\n", | |
1809 | current->comm, preempt_count(), task_pid_nr(current)); | |
1810 | printk(KERN_ERR " last function: "); | |
1811 | print_symbol("%s\n", (unsigned long)f); | |
1812 | debug_show_held_locks(current); | |
1813 | dump_stack(); | |
1814 | } | |
1815 | ||
8b03ae3c | 1816 | spin_lock_irq(&gcwq->lock); |
a62428c0 | 1817 | |
fb0e7beb TH |
1818 | /* clear cpu intensive status */ |
1819 | if (unlikely(cpu_intensive)) | |
1820 | worker_clr_flags(worker, WORKER_CPU_INTENSIVE); | |
1821 | ||
a62428c0 | 1822 | /* we're done with it, release */ |
c8e55f36 | 1823 | hlist_del_init(&worker->hentry); |
c34056a3 | 1824 | worker->current_work = NULL; |
8cca0eea | 1825 | worker->current_cwq = NULL; |
73f53c4a | 1826 | cwq_dec_nr_in_flight(cwq, work_color); |
a62428c0 TH |
1827 | } |
1828 | ||
affee4b2 TH |
1829 | /** |
1830 | * process_scheduled_works - process scheduled works | |
1831 | * @worker: self | |
1832 | * | |
1833 | * Process all scheduled works. Please note that the scheduled list | |
1834 | * may change while processing a work, so this function repeatedly | |
1835 | * fetches a work from the top and executes it. | |
1836 | * | |
1837 | * CONTEXT: | |
8b03ae3c | 1838 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed |
affee4b2 TH |
1839 | * multiple times. |
1840 | */ | |
1841 | static void process_scheduled_works(struct worker *worker) | |
1da177e4 | 1842 | { |
affee4b2 TH |
1843 | while (!list_empty(&worker->scheduled)) { |
1844 | struct work_struct *work = list_first_entry(&worker->scheduled, | |
1da177e4 | 1845 | struct work_struct, entry); |
c34056a3 | 1846 | process_one_work(worker, work); |
1da177e4 | 1847 | } |
1da177e4 LT |
1848 | } |
1849 | ||
4690c4ab TH |
1850 | /** |
1851 | * worker_thread - the worker thread function | |
c34056a3 | 1852 | * @__worker: self |
4690c4ab | 1853 | * |
e22bee78 TH |
1854 | * The gcwq worker thread function. There's a single dynamic pool of |
1855 | * these per each cpu. These workers process all works regardless of | |
1856 | * their specific target workqueue. The only exception is works which | |
1857 | * belong to workqueues with a rescuer which will be explained in | |
1858 | * rescuer_thread(). | |
4690c4ab | 1859 | */ |
c34056a3 | 1860 | static int worker_thread(void *__worker) |
1da177e4 | 1861 | { |
c34056a3 | 1862 | struct worker *worker = __worker; |
8b03ae3c | 1863 | struct global_cwq *gcwq = worker->gcwq; |
1da177e4 | 1864 | |
e22bee78 TH |
1865 | /* tell the scheduler that this is a workqueue worker */ |
1866 | worker->task->flags |= PF_WQ_WORKER; | |
c8e55f36 | 1867 | woke_up: |
c8e55f36 | 1868 | spin_lock_irq(&gcwq->lock); |
1da177e4 | 1869 | |
c8e55f36 TH |
1870 | /* DIE can be set only while we're idle, checking here is enough */ |
1871 | if (worker->flags & WORKER_DIE) { | |
1872 | spin_unlock_irq(&gcwq->lock); | |
e22bee78 | 1873 | worker->task->flags &= ~PF_WQ_WORKER; |
c8e55f36 TH |
1874 | return 0; |
1875 | } | |
affee4b2 | 1876 | |
c8e55f36 | 1877 | worker_leave_idle(worker); |
db7bccf4 | 1878 | recheck: |
e22bee78 TH |
1879 | /* no more worker necessary? */ |
1880 | if (!need_more_worker(gcwq)) | |
1881 | goto sleep; | |
1882 | ||
1883 | /* do we need to manage? */ | |
1884 | if (unlikely(!may_start_working(gcwq)) && manage_workers(worker)) | |
1885 | goto recheck; | |
1886 | ||
c8e55f36 TH |
1887 | /* |
1888 | * ->scheduled list can only be filled while a worker is | |
1889 | * preparing to process a work or actually processing it. | |
1890 | * Make sure nobody diddled with it while I was sleeping. | |
1891 | */ | |
1892 | BUG_ON(!list_empty(&worker->scheduled)); | |
1893 | ||
e22bee78 TH |
1894 | /* |
1895 | * When control reaches this point, we're guaranteed to have | |
1896 | * at least one idle worker or that someone else has already | |
1897 | * assumed the manager role. | |
1898 | */ | |
1899 | worker_clr_flags(worker, WORKER_PREP); | |
1900 | ||
1901 | do { | |
c8e55f36 | 1902 | struct work_struct *work = |
7e11629d | 1903 | list_first_entry(&gcwq->worklist, |
c8e55f36 TH |
1904 | struct work_struct, entry); |
1905 | ||
1906 | if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { | |
1907 | /* optimization path, not strictly necessary */ | |
1908 | process_one_work(worker, work); | |
1909 | if (unlikely(!list_empty(&worker->scheduled))) | |
affee4b2 | 1910 | process_scheduled_works(worker); |
c8e55f36 TH |
1911 | } else { |
1912 | move_linked_works(work, &worker->scheduled, NULL); | |
1913 | process_scheduled_works(worker); | |
affee4b2 | 1914 | } |
e22bee78 TH |
1915 | } while (keep_working(gcwq)); |
1916 | ||
1917 | worker_set_flags(worker, WORKER_PREP, false); | |
d313dd85 | 1918 | sleep: |
e22bee78 TH |
1919 | if (unlikely(need_to_manage_workers(gcwq)) && manage_workers(worker)) |
1920 | goto recheck; | |
d313dd85 | 1921 | |
c8e55f36 | 1922 | /* |
e22bee78 TH |
1923 | * gcwq->lock is held and there's no work to process and no |
1924 | * need to manage, sleep. Workers are woken up only while | |
1925 | * holding gcwq->lock or from local cpu, so setting the | |
1926 | * current state before releasing gcwq->lock is enough to | |
1927 | * prevent losing any event. | |
c8e55f36 TH |
1928 | */ |
1929 | worker_enter_idle(worker); | |
1930 | __set_current_state(TASK_INTERRUPTIBLE); | |
1931 | spin_unlock_irq(&gcwq->lock); | |
1932 | schedule(); | |
1933 | goto woke_up; | |
1da177e4 LT |
1934 | } |
1935 | ||
e22bee78 TH |
1936 | /** |
1937 | * rescuer_thread - the rescuer thread function | |
1938 | * @__wq: the associated workqueue | |
1939 | * | |
1940 | * Workqueue rescuer thread function. There's one rescuer for each | |
1941 | * workqueue which has WQ_RESCUER set. | |
1942 | * | |
1943 | * Regular work processing on a gcwq may block trying to create a new | |
1944 | * worker which uses GFP_KERNEL allocation which has slight chance of | |
1945 | * developing into deadlock if some works currently on the same queue | |
1946 | * need to be processed to satisfy the GFP_KERNEL allocation. This is | |
1947 | * the problem rescuer solves. | |
1948 | * | |
1949 | * When such condition is possible, the gcwq summons rescuers of all | |
1950 | * workqueues which have works queued on the gcwq and let them process | |
1951 | * those works so that forward progress can be guaranteed. | |
1952 | * | |
1953 | * This should happen rarely. | |
1954 | */ | |
1955 | static int rescuer_thread(void *__wq) | |
1956 | { | |
1957 | struct workqueue_struct *wq = __wq; | |
1958 | struct worker *rescuer = wq->rescuer; | |
1959 | struct list_head *scheduled = &rescuer->scheduled; | |
f3421797 | 1960 | bool is_unbound = wq->flags & WQ_UNBOUND; |
e22bee78 TH |
1961 | unsigned int cpu; |
1962 | ||
1963 | set_user_nice(current, RESCUER_NICE_LEVEL); | |
1964 | repeat: | |
1965 | set_current_state(TASK_INTERRUPTIBLE); | |
1966 | ||
1967 | if (kthread_should_stop()) | |
1968 | return 0; | |
1969 | ||
f3421797 TH |
1970 | /* |
1971 | * See whether any cpu is asking for help. Unbounded | |
1972 | * workqueues use cpu 0 in mayday_mask for CPU_UNBOUND. | |
1973 | */ | |
f2e005aa | 1974 | for_each_mayday_cpu(cpu, wq->mayday_mask) { |
f3421797 TH |
1975 | unsigned int tcpu = is_unbound ? WORK_CPU_UNBOUND : cpu; |
1976 | struct cpu_workqueue_struct *cwq = get_cwq(tcpu, wq); | |
e22bee78 TH |
1977 | struct global_cwq *gcwq = cwq->gcwq; |
1978 | struct work_struct *work, *n; | |
1979 | ||
1980 | __set_current_state(TASK_RUNNING); | |
f2e005aa | 1981 | mayday_clear_cpu(cpu, wq->mayday_mask); |
e22bee78 TH |
1982 | |
1983 | /* migrate to the target cpu if possible */ | |
1984 | rescuer->gcwq = gcwq; | |
1985 | worker_maybe_bind_and_lock(rescuer); | |
1986 | ||
1987 | /* | |
1988 | * Slurp in all works issued via this workqueue and | |
1989 | * process'em. | |
1990 | */ | |
1991 | BUG_ON(!list_empty(&rescuer->scheduled)); | |
1992 | list_for_each_entry_safe(work, n, &gcwq->worklist, entry) | |
1993 | if (get_work_cwq(work) == cwq) | |
1994 | move_linked_works(work, scheduled, &n); | |
1995 | ||
1996 | process_scheduled_works(rescuer); | |
1997 | spin_unlock_irq(&gcwq->lock); | |
1998 | } | |
1999 | ||
2000 | schedule(); | |
2001 | goto repeat; | |
1da177e4 LT |
2002 | } |
2003 | ||
fc2e4d70 ON |
2004 | struct wq_barrier { |
2005 | struct work_struct work; | |
2006 | struct completion done; | |
2007 | }; | |
2008 | ||
2009 | static void wq_barrier_func(struct work_struct *work) | |
2010 | { | |
2011 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); | |
2012 | complete(&barr->done); | |
2013 | } | |
2014 | ||
4690c4ab TH |
2015 | /** |
2016 | * insert_wq_barrier - insert a barrier work | |
2017 | * @cwq: cwq to insert barrier into | |
2018 | * @barr: wq_barrier to insert | |
affee4b2 TH |
2019 | * @target: target work to attach @barr to |
2020 | * @worker: worker currently executing @target, NULL if @target is not executing | |
4690c4ab | 2021 | * |
affee4b2 TH |
2022 | * @barr is linked to @target such that @barr is completed only after |
2023 | * @target finishes execution. Please note that the ordering | |
2024 | * guarantee is observed only with respect to @target and on the local | |
2025 | * cpu. | |
2026 | * | |
2027 | * Currently, a queued barrier can't be canceled. This is because | |
2028 | * try_to_grab_pending() can't determine whether the work to be | |
2029 | * grabbed is at the head of the queue and thus can't clear LINKED | |
2030 | * flag of the previous work while there must be a valid next work | |
2031 | * after a work with LINKED flag set. | |
2032 | * | |
2033 | * Note that when @worker is non-NULL, @target may be modified | |
2034 | * underneath us, so we can't reliably determine cwq from @target. | |
4690c4ab TH |
2035 | * |
2036 | * CONTEXT: | |
8b03ae3c | 2037 | * spin_lock_irq(gcwq->lock). |
4690c4ab | 2038 | */ |
83c22520 | 2039 | static void insert_wq_barrier(struct cpu_workqueue_struct *cwq, |
affee4b2 TH |
2040 | struct wq_barrier *barr, |
2041 | struct work_struct *target, struct worker *worker) | |
fc2e4d70 | 2042 | { |
affee4b2 TH |
2043 | struct list_head *head; |
2044 | unsigned int linked = 0; | |
2045 | ||
dc186ad7 | 2046 | /* |
8b03ae3c | 2047 | * debugobject calls are safe here even with gcwq->lock locked |
dc186ad7 TG |
2048 | * as we know for sure that this will not trigger any of the |
2049 | * checks and call back into the fixup functions where we | |
2050 | * might deadlock. | |
2051 | */ | |
2052 | INIT_WORK_ON_STACK(&barr->work, wq_barrier_func); | |
22df02bb | 2053 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
fc2e4d70 | 2054 | init_completion(&barr->done); |
83c22520 | 2055 | |
affee4b2 TH |
2056 | /* |
2057 | * If @target is currently being executed, schedule the | |
2058 | * barrier to the worker; otherwise, put it after @target. | |
2059 | */ | |
2060 | if (worker) | |
2061 | head = worker->scheduled.next; | |
2062 | else { | |
2063 | unsigned long *bits = work_data_bits(target); | |
2064 | ||
2065 | head = target->entry.next; | |
2066 | /* there can already be other linked works, inherit and set */ | |
2067 | linked = *bits & WORK_STRUCT_LINKED; | |
2068 | __set_bit(WORK_STRUCT_LINKED_BIT, bits); | |
2069 | } | |
2070 | ||
dc186ad7 | 2071 | debug_work_activate(&barr->work); |
affee4b2 TH |
2072 | insert_work(cwq, &barr->work, head, |
2073 | work_color_to_flags(WORK_NO_COLOR) | linked); | |
fc2e4d70 ON |
2074 | } |
2075 | ||
73f53c4a TH |
2076 | /** |
2077 | * flush_workqueue_prep_cwqs - prepare cwqs for workqueue flushing | |
2078 | * @wq: workqueue being flushed | |
2079 | * @flush_color: new flush color, < 0 for no-op | |
2080 | * @work_color: new work color, < 0 for no-op | |
2081 | * | |
2082 | * Prepare cwqs for workqueue flushing. | |
2083 | * | |
2084 | * If @flush_color is non-negative, flush_color on all cwqs should be | |
2085 | * -1. If no cwq has in-flight commands at the specified color, all | |
2086 | * cwq->flush_color's stay at -1 and %false is returned. If any cwq | |
2087 | * has in flight commands, its cwq->flush_color is set to | |
2088 | * @flush_color, @wq->nr_cwqs_to_flush is updated accordingly, cwq | |
2089 | * wakeup logic is armed and %true is returned. | |
2090 | * | |
2091 | * The caller should have initialized @wq->first_flusher prior to | |
2092 | * calling this function with non-negative @flush_color. If | |
2093 | * @flush_color is negative, no flush color update is done and %false | |
2094 | * is returned. | |
2095 | * | |
2096 | * If @work_color is non-negative, all cwqs should have the same | |
2097 | * work_color which is previous to @work_color and all will be | |
2098 | * advanced to @work_color. | |
2099 | * | |
2100 | * CONTEXT: | |
2101 | * mutex_lock(wq->flush_mutex). | |
2102 | * | |
2103 | * RETURNS: | |
2104 | * %true if @flush_color >= 0 and there's something to flush. %false | |
2105 | * otherwise. | |
2106 | */ | |
2107 | static bool flush_workqueue_prep_cwqs(struct workqueue_struct *wq, | |
2108 | int flush_color, int work_color) | |
1da177e4 | 2109 | { |
73f53c4a TH |
2110 | bool wait = false; |
2111 | unsigned int cpu; | |
1da177e4 | 2112 | |
73f53c4a TH |
2113 | if (flush_color >= 0) { |
2114 | BUG_ON(atomic_read(&wq->nr_cwqs_to_flush)); | |
2115 | atomic_set(&wq->nr_cwqs_to_flush, 1); | |
1da177e4 | 2116 | } |
2355b70f | 2117 | |
f3421797 | 2118 | for_each_cwq_cpu(cpu, wq) { |
73f53c4a | 2119 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
8b03ae3c | 2120 | struct global_cwq *gcwq = cwq->gcwq; |
fc2e4d70 | 2121 | |
8b03ae3c | 2122 | spin_lock_irq(&gcwq->lock); |
83c22520 | 2123 | |
73f53c4a TH |
2124 | if (flush_color >= 0) { |
2125 | BUG_ON(cwq->flush_color != -1); | |
fc2e4d70 | 2126 | |
73f53c4a TH |
2127 | if (cwq->nr_in_flight[flush_color]) { |
2128 | cwq->flush_color = flush_color; | |
2129 | atomic_inc(&wq->nr_cwqs_to_flush); | |
2130 | wait = true; | |
2131 | } | |
2132 | } | |
1da177e4 | 2133 | |
73f53c4a TH |
2134 | if (work_color >= 0) { |
2135 | BUG_ON(work_color != work_next_color(cwq->work_color)); | |
2136 | cwq->work_color = work_color; | |
2137 | } | |
1da177e4 | 2138 | |
8b03ae3c | 2139 | spin_unlock_irq(&gcwq->lock); |
1da177e4 | 2140 | } |
2355b70f | 2141 | |
73f53c4a TH |
2142 | if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_cwqs_to_flush)) |
2143 | complete(&wq->first_flusher->done); | |
14441960 | 2144 | |
73f53c4a | 2145 | return wait; |
1da177e4 LT |
2146 | } |
2147 | ||
0fcb78c2 | 2148 | /** |
1da177e4 | 2149 | * flush_workqueue - ensure that any scheduled work has run to completion. |
0fcb78c2 | 2150 | * @wq: workqueue to flush |
1da177e4 LT |
2151 | * |
2152 | * Forces execution of the workqueue and blocks until its completion. | |
2153 | * This is typically used in driver shutdown handlers. | |
2154 | * | |
fc2e4d70 ON |
2155 | * We sleep until all works which were queued on entry have been handled, |
2156 | * but we are not livelocked by new incoming ones. | |
1da177e4 | 2157 | */ |
7ad5b3a5 | 2158 | void flush_workqueue(struct workqueue_struct *wq) |
1da177e4 | 2159 | { |
73f53c4a TH |
2160 | struct wq_flusher this_flusher = { |
2161 | .list = LIST_HEAD_INIT(this_flusher.list), | |
2162 | .flush_color = -1, | |
2163 | .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), | |
2164 | }; | |
2165 | int next_color; | |
1da177e4 | 2166 | |
3295f0ef IM |
2167 | lock_map_acquire(&wq->lockdep_map); |
2168 | lock_map_release(&wq->lockdep_map); | |
73f53c4a TH |
2169 | |
2170 | mutex_lock(&wq->flush_mutex); | |
2171 | ||
2172 | /* | |
2173 | * Start-to-wait phase | |
2174 | */ | |
2175 | next_color = work_next_color(wq->work_color); | |
2176 | ||
2177 | if (next_color != wq->flush_color) { | |
2178 | /* | |
2179 | * Color space is not full. The current work_color | |
2180 | * becomes our flush_color and work_color is advanced | |
2181 | * by one. | |
2182 | */ | |
2183 | BUG_ON(!list_empty(&wq->flusher_overflow)); | |
2184 | this_flusher.flush_color = wq->work_color; | |
2185 | wq->work_color = next_color; | |
2186 | ||
2187 | if (!wq->first_flusher) { | |
2188 | /* no flush in progress, become the first flusher */ | |
2189 | BUG_ON(wq->flush_color != this_flusher.flush_color); | |
2190 | ||
2191 | wq->first_flusher = &this_flusher; | |
2192 | ||
2193 | if (!flush_workqueue_prep_cwqs(wq, wq->flush_color, | |
2194 | wq->work_color)) { | |
2195 | /* nothing to flush, done */ | |
2196 | wq->flush_color = next_color; | |
2197 | wq->first_flusher = NULL; | |
2198 | goto out_unlock; | |
2199 | } | |
2200 | } else { | |
2201 | /* wait in queue */ | |
2202 | BUG_ON(wq->flush_color == this_flusher.flush_color); | |
2203 | list_add_tail(&this_flusher.list, &wq->flusher_queue); | |
2204 | flush_workqueue_prep_cwqs(wq, -1, wq->work_color); | |
2205 | } | |
2206 | } else { | |
2207 | /* | |
2208 | * Oops, color space is full, wait on overflow queue. | |
2209 | * The next flush completion will assign us | |
2210 | * flush_color and transfer to flusher_queue. | |
2211 | */ | |
2212 | list_add_tail(&this_flusher.list, &wq->flusher_overflow); | |
2213 | } | |
2214 | ||
2215 | mutex_unlock(&wq->flush_mutex); | |
2216 | ||
2217 | wait_for_completion(&this_flusher.done); | |
2218 | ||
2219 | /* | |
2220 | * Wake-up-and-cascade phase | |
2221 | * | |
2222 | * First flushers are responsible for cascading flushes and | |
2223 | * handling overflow. Non-first flushers can simply return. | |
2224 | */ | |
2225 | if (wq->first_flusher != &this_flusher) | |
2226 | return; | |
2227 | ||
2228 | mutex_lock(&wq->flush_mutex); | |
2229 | ||
4ce48b37 TH |
2230 | /* we might have raced, check again with mutex held */ |
2231 | if (wq->first_flusher != &this_flusher) | |
2232 | goto out_unlock; | |
2233 | ||
73f53c4a TH |
2234 | wq->first_flusher = NULL; |
2235 | ||
2236 | BUG_ON(!list_empty(&this_flusher.list)); | |
2237 | BUG_ON(wq->flush_color != this_flusher.flush_color); | |
2238 | ||
2239 | while (true) { | |
2240 | struct wq_flusher *next, *tmp; | |
2241 | ||
2242 | /* complete all the flushers sharing the current flush color */ | |
2243 | list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { | |
2244 | if (next->flush_color != wq->flush_color) | |
2245 | break; | |
2246 | list_del_init(&next->list); | |
2247 | complete(&next->done); | |
2248 | } | |
2249 | ||
2250 | BUG_ON(!list_empty(&wq->flusher_overflow) && | |
2251 | wq->flush_color != work_next_color(wq->work_color)); | |
2252 | ||
2253 | /* this flush_color is finished, advance by one */ | |
2254 | wq->flush_color = work_next_color(wq->flush_color); | |
2255 | ||
2256 | /* one color has been freed, handle overflow queue */ | |
2257 | if (!list_empty(&wq->flusher_overflow)) { | |
2258 | /* | |
2259 | * Assign the same color to all overflowed | |
2260 | * flushers, advance work_color and append to | |
2261 | * flusher_queue. This is the start-to-wait | |
2262 | * phase for these overflowed flushers. | |
2263 | */ | |
2264 | list_for_each_entry(tmp, &wq->flusher_overflow, list) | |
2265 | tmp->flush_color = wq->work_color; | |
2266 | ||
2267 | wq->work_color = work_next_color(wq->work_color); | |
2268 | ||
2269 | list_splice_tail_init(&wq->flusher_overflow, | |
2270 | &wq->flusher_queue); | |
2271 | flush_workqueue_prep_cwqs(wq, -1, wq->work_color); | |
2272 | } | |
2273 | ||
2274 | if (list_empty(&wq->flusher_queue)) { | |
2275 | BUG_ON(wq->flush_color != wq->work_color); | |
2276 | break; | |
2277 | } | |
2278 | ||
2279 | /* | |
2280 | * Need to flush more colors. Make the next flusher | |
2281 | * the new first flusher and arm cwqs. | |
2282 | */ | |
2283 | BUG_ON(wq->flush_color == wq->work_color); | |
2284 | BUG_ON(wq->flush_color != next->flush_color); | |
2285 | ||
2286 | list_del_init(&next->list); | |
2287 | wq->first_flusher = next; | |
2288 | ||
2289 | if (flush_workqueue_prep_cwqs(wq, wq->flush_color, -1)) | |
2290 | break; | |
2291 | ||
2292 | /* | |
2293 | * Meh... this color is already done, clear first | |
2294 | * flusher and repeat cascading. | |
2295 | */ | |
2296 | wq->first_flusher = NULL; | |
2297 | } | |
2298 | ||
2299 | out_unlock: | |
2300 | mutex_unlock(&wq->flush_mutex); | |
1da177e4 | 2301 | } |
ae90dd5d | 2302 | EXPORT_SYMBOL_GPL(flush_workqueue); |
1da177e4 | 2303 | |
db700897 ON |
2304 | /** |
2305 | * flush_work - block until a work_struct's callback has terminated | |
2306 | * @work: the work which is to be flushed | |
2307 | * | |
a67da70d ON |
2308 | * Returns false if @work has already terminated. |
2309 | * | |
db700897 ON |
2310 | * It is expected that, prior to calling flush_work(), the caller has |
2311 | * arranged for the work to not be requeued, otherwise it doesn't make | |
2312 | * sense to use this function. | |
2313 | */ | |
2314 | int flush_work(struct work_struct *work) | |
2315 | { | |
affee4b2 | 2316 | struct worker *worker = NULL; |
8b03ae3c | 2317 | struct global_cwq *gcwq; |
db700897 | 2318 | struct cpu_workqueue_struct *cwq; |
db700897 ON |
2319 | struct wq_barrier barr; |
2320 | ||
2321 | might_sleep(); | |
7a22ad75 TH |
2322 | gcwq = get_work_gcwq(work); |
2323 | if (!gcwq) | |
db700897 ON |
2324 | return 0; |
2325 | ||
8b03ae3c | 2326 | spin_lock_irq(&gcwq->lock); |
db700897 ON |
2327 | if (!list_empty(&work->entry)) { |
2328 | /* | |
2329 | * See the comment near try_to_grab_pending()->smp_rmb(). | |
7a22ad75 TH |
2330 | * If it was re-queued to a different gcwq under us, we |
2331 | * are not going to wait. | |
db700897 ON |
2332 | */ |
2333 | smp_rmb(); | |
7a22ad75 TH |
2334 | cwq = get_work_cwq(work); |
2335 | if (unlikely(!cwq || gcwq != cwq->gcwq)) | |
4690c4ab | 2336 | goto already_gone; |
db700897 | 2337 | } else { |
7a22ad75 | 2338 | worker = find_worker_executing_work(gcwq, work); |
affee4b2 | 2339 | if (!worker) |
4690c4ab | 2340 | goto already_gone; |
7a22ad75 | 2341 | cwq = worker->current_cwq; |
db700897 | 2342 | } |
db700897 | 2343 | |
affee4b2 | 2344 | insert_wq_barrier(cwq, &barr, work, worker); |
8b03ae3c | 2345 | spin_unlock_irq(&gcwq->lock); |
7a22ad75 TH |
2346 | |
2347 | lock_map_acquire(&cwq->wq->lockdep_map); | |
2348 | lock_map_release(&cwq->wq->lockdep_map); | |
db700897 ON |
2349 | |
2350 | wait_for_completion(&barr.done); | |
dc186ad7 | 2351 | destroy_work_on_stack(&barr.work); |
db700897 | 2352 | return 1; |
4690c4ab | 2353 | already_gone: |
8b03ae3c | 2354 | spin_unlock_irq(&gcwq->lock); |
4690c4ab | 2355 | return 0; |
db700897 ON |
2356 | } |
2357 | EXPORT_SYMBOL_GPL(flush_work); | |
2358 | ||
6e84d644 | 2359 | /* |
1f1f642e | 2360 | * Upon a successful return (>= 0), the caller "owns" WORK_STRUCT_PENDING bit, |
6e84d644 ON |
2361 | * so this work can't be re-armed in any way. |
2362 | */ | |
2363 | static int try_to_grab_pending(struct work_struct *work) | |
2364 | { | |
8b03ae3c | 2365 | struct global_cwq *gcwq; |
1f1f642e | 2366 | int ret = -1; |
6e84d644 | 2367 | |
22df02bb | 2368 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
1f1f642e | 2369 | return 0; |
6e84d644 ON |
2370 | |
2371 | /* | |
2372 | * The queueing is in progress, or it is already queued. Try to | |
2373 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. | |
2374 | */ | |
7a22ad75 TH |
2375 | gcwq = get_work_gcwq(work); |
2376 | if (!gcwq) | |
6e84d644 ON |
2377 | return ret; |
2378 | ||
8b03ae3c | 2379 | spin_lock_irq(&gcwq->lock); |
6e84d644 ON |
2380 | if (!list_empty(&work->entry)) { |
2381 | /* | |
7a22ad75 | 2382 | * This work is queued, but perhaps we locked the wrong gcwq. |
6e84d644 ON |
2383 | * In that case we must see the new value after rmb(), see |
2384 | * insert_work()->wmb(). | |
2385 | */ | |
2386 | smp_rmb(); | |
7a22ad75 | 2387 | if (gcwq == get_work_gcwq(work)) { |
dc186ad7 | 2388 | debug_work_deactivate(work); |
6e84d644 | 2389 | list_del_init(&work->entry); |
7a22ad75 TH |
2390 | cwq_dec_nr_in_flight(get_work_cwq(work), |
2391 | get_work_color(work)); | |
6e84d644 ON |
2392 | ret = 1; |
2393 | } | |
2394 | } | |
8b03ae3c | 2395 | spin_unlock_irq(&gcwq->lock); |
6e84d644 ON |
2396 | |
2397 | return ret; | |
2398 | } | |
2399 | ||
7a22ad75 | 2400 | static void wait_on_cpu_work(struct global_cwq *gcwq, struct work_struct *work) |
b89deed3 ON |
2401 | { |
2402 | struct wq_barrier barr; | |
affee4b2 | 2403 | struct worker *worker; |
b89deed3 | 2404 | |
8b03ae3c | 2405 | spin_lock_irq(&gcwq->lock); |
b89deed3 | 2406 | |
7a22ad75 TH |
2407 | worker = find_worker_executing_work(gcwq, work); |
2408 | if (unlikely(worker)) | |
2409 | insert_wq_barrier(worker->current_cwq, &barr, work, worker); | |
affee4b2 | 2410 | |
8b03ae3c | 2411 | spin_unlock_irq(&gcwq->lock); |
b89deed3 | 2412 | |
affee4b2 | 2413 | if (unlikely(worker)) { |
b89deed3 | 2414 | wait_for_completion(&barr.done); |
dc186ad7 TG |
2415 | destroy_work_on_stack(&barr.work); |
2416 | } | |
b89deed3 ON |
2417 | } |
2418 | ||
6e84d644 | 2419 | static void wait_on_work(struct work_struct *work) |
b89deed3 | 2420 | { |
b1f4ec17 | 2421 | int cpu; |
b89deed3 | 2422 | |
f293ea92 ON |
2423 | might_sleep(); |
2424 | ||
3295f0ef IM |
2425 | lock_map_acquire(&work->lockdep_map); |
2426 | lock_map_release(&work->lockdep_map); | |
4e6045f1 | 2427 | |
f3421797 | 2428 | for_each_gcwq_cpu(cpu) |
7a22ad75 | 2429 | wait_on_cpu_work(get_gcwq(cpu), work); |
6e84d644 ON |
2430 | } |
2431 | ||
1f1f642e ON |
2432 | static int __cancel_work_timer(struct work_struct *work, |
2433 | struct timer_list* timer) | |
2434 | { | |
2435 | int ret; | |
2436 | ||
2437 | do { | |
2438 | ret = (timer && likely(del_timer(timer))); | |
2439 | if (!ret) | |
2440 | ret = try_to_grab_pending(work); | |
2441 | wait_on_work(work); | |
2442 | } while (unlikely(ret < 0)); | |
2443 | ||
7a22ad75 | 2444 | clear_work_data(work); |
1f1f642e ON |
2445 | return ret; |
2446 | } | |
2447 | ||
6e84d644 ON |
2448 | /** |
2449 | * cancel_work_sync - block until a work_struct's callback has terminated | |
2450 | * @work: the work which is to be flushed | |
2451 | * | |
1f1f642e ON |
2452 | * Returns true if @work was pending. |
2453 | * | |
6e84d644 ON |
2454 | * cancel_work_sync() will cancel the work if it is queued. If the work's |
2455 | * callback appears to be running, cancel_work_sync() will block until it | |
2456 | * has completed. | |
2457 | * | |
2458 | * It is possible to use this function if the work re-queues itself. It can | |
2459 | * cancel the work even if it migrates to another workqueue, however in that | |
2460 | * case it only guarantees that work->func() has completed on the last queued | |
2461 | * workqueue. | |
2462 | * | |
2463 | * cancel_work_sync(&delayed_work->work) should be used only if ->timer is not | |
2464 | * pending, otherwise it goes into a busy-wait loop until the timer expires. | |
2465 | * | |
2466 | * The caller must ensure that workqueue_struct on which this work was last | |
2467 | * queued can't be destroyed before this function returns. | |
2468 | */ | |
1f1f642e | 2469 | int cancel_work_sync(struct work_struct *work) |
6e84d644 | 2470 | { |
1f1f642e | 2471 | return __cancel_work_timer(work, NULL); |
b89deed3 | 2472 | } |
28e53bdd | 2473 | EXPORT_SYMBOL_GPL(cancel_work_sync); |
b89deed3 | 2474 | |
6e84d644 | 2475 | /** |
f5a421a4 | 2476 | * cancel_delayed_work_sync - reliably kill off a delayed work. |
6e84d644 ON |
2477 | * @dwork: the delayed work struct |
2478 | * | |
1f1f642e ON |
2479 | * Returns true if @dwork was pending. |
2480 | * | |
6e84d644 ON |
2481 | * It is possible to use this function if @dwork rearms itself via queue_work() |
2482 | * or queue_delayed_work(). See also the comment for cancel_work_sync(). | |
2483 | */ | |
1f1f642e | 2484 | int cancel_delayed_work_sync(struct delayed_work *dwork) |
6e84d644 | 2485 | { |
1f1f642e | 2486 | return __cancel_work_timer(&dwork->work, &dwork->timer); |
6e84d644 | 2487 | } |
f5a421a4 | 2488 | EXPORT_SYMBOL(cancel_delayed_work_sync); |
1da177e4 | 2489 | |
0fcb78c2 REB |
2490 | /** |
2491 | * schedule_work - put work task in global workqueue | |
2492 | * @work: job to be done | |
2493 | * | |
5b0f437d BVA |
2494 | * Returns zero if @work was already on the kernel-global workqueue and |
2495 | * non-zero otherwise. | |
2496 | * | |
2497 | * This puts a job in the kernel-global workqueue if it was not already | |
2498 | * queued and leaves it in the same position on the kernel-global | |
2499 | * workqueue otherwise. | |
0fcb78c2 | 2500 | */ |
7ad5b3a5 | 2501 | int schedule_work(struct work_struct *work) |
1da177e4 | 2502 | { |
d320c038 | 2503 | return queue_work(system_wq, work); |
1da177e4 | 2504 | } |
ae90dd5d | 2505 | EXPORT_SYMBOL(schedule_work); |
1da177e4 | 2506 | |
c1a220e7 ZR |
2507 | /* |
2508 | * schedule_work_on - put work task on a specific cpu | |
2509 | * @cpu: cpu to put the work task on | |
2510 | * @work: job to be done | |
2511 | * | |
2512 | * This puts a job on a specific cpu | |
2513 | */ | |
2514 | int schedule_work_on(int cpu, struct work_struct *work) | |
2515 | { | |
d320c038 | 2516 | return queue_work_on(cpu, system_wq, work); |
c1a220e7 ZR |
2517 | } |
2518 | EXPORT_SYMBOL(schedule_work_on); | |
2519 | ||
0fcb78c2 REB |
2520 | /** |
2521 | * schedule_delayed_work - put work task in global workqueue after delay | |
52bad64d DH |
2522 | * @dwork: job to be done |
2523 | * @delay: number of jiffies to wait or 0 for immediate execution | |
0fcb78c2 REB |
2524 | * |
2525 | * After waiting for a given time this puts a job in the kernel-global | |
2526 | * workqueue. | |
2527 | */ | |
7ad5b3a5 | 2528 | int schedule_delayed_work(struct delayed_work *dwork, |
82f67cd9 | 2529 | unsigned long delay) |
1da177e4 | 2530 | { |
d320c038 | 2531 | return queue_delayed_work(system_wq, dwork, delay); |
1da177e4 | 2532 | } |
ae90dd5d | 2533 | EXPORT_SYMBOL(schedule_delayed_work); |
1da177e4 | 2534 | |
8c53e463 LT |
2535 | /** |
2536 | * flush_delayed_work - block until a dwork_struct's callback has terminated | |
2537 | * @dwork: the delayed work which is to be flushed | |
2538 | * | |
2539 | * Any timeout is cancelled, and any pending work is run immediately. | |
2540 | */ | |
2541 | void flush_delayed_work(struct delayed_work *dwork) | |
2542 | { | |
2543 | if (del_timer_sync(&dwork->timer)) { | |
7a22ad75 | 2544 | __queue_work(get_cpu(), get_work_cwq(&dwork->work)->wq, |
4690c4ab | 2545 | &dwork->work); |
8c53e463 LT |
2546 | put_cpu(); |
2547 | } | |
2548 | flush_work(&dwork->work); | |
2549 | } | |
2550 | EXPORT_SYMBOL(flush_delayed_work); | |
2551 | ||
0fcb78c2 REB |
2552 | /** |
2553 | * schedule_delayed_work_on - queue work in global workqueue on CPU after delay | |
2554 | * @cpu: cpu to use | |
52bad64d | 2555 | * @dwork: job to be done |
0fcb78c2 REB |
2556 | * @delay: number of jiffies to wait |
2557 | * | |
2558 | * After waiting for a given time this puts a job in the kernel-global | |
2559 | * workqueue on the specified CPU. | |
2560 | */ | |
1da177e4 | 2561 | int schedule_delayed_work_on(int cpu, |
52bad64d | 2562 | struct delayed_work *dwork, unsigned long delay) |
1da177e4 | 2563 | { |
d320c038 | 2564 | return queue_delayed_work_on(cpu, system_wq, dwork, delay); |
1da177e4 | 2565 | } |
ae90dd5d | 2566 | EXPORT_SYMBOL(schedule_delayed_work_on); |
1da177e4 | 2567 | |
b6136773 AM |
2568 | /** |
2569 | * schedule_on_each_cpu - call a function on each online CPU from keventd | |
2570 | * @func: the function to call | |
b6136773 AM |
2571 | * |
2572 | * Returns zero on success. | |
2573 | * Returns -ve errno on failure. | |
2574 | * | |
b6136773 AM |
2575 | * schedule_on_each_cpu() is very slow. |
2576 | */ | |
65f27f38 | 2577 | int schedule_on_each_cpu(work_func_t func) |
15316ba8 CL |
2578 | { |
2579 | int cpu; | |
38f51568 | 2580 | struct work_struct __percpu *works; |
15316ba8 | 2581 | |
b6136773 AM |
2582 | works = alloc_percpu(struct work_struct); |
2583 | if (!works) | |
15316ba8 | 2584 | return -ENOMEM; |
b6136773 | 2585 | |
93981800 TH |
2586 | get_online_cpus(); |
2587 | ||
15316ba8 | 2588 | for_each_online_cpu(cpu) { |
9bfb1839 IM |
2589 | struct work_struct *work = per_cpu_ptr(works, cpu); |
2590 | ||
2591 | INIT_WORK(work, func); | |
b71ab8c2 | 2592 | schedule_work_on(cpu, work); |
65a64464 | 2593 | } |
93981800 TH |
2594 | |
2595 | for_each_online_cpu(cpu) | |
2596 | flush_work(per_cpu_ptr(works, cpu)); | |
2597 | ||
95402b38 | 2598 | put_online_cpus(); |
b6136773 | 2599 | free_percpu(works); |
15316ba8 CL |
2600 | return 0; |
2601 | } | |
2602 | ||
eef6a7d5 AS |
2603 | /** |
2604 | * flush_scheduled_work - ensure that any scheduled work has run to completion. | |
2605 | * | |
2606 | * Forces execution of the kernel-global workqueue and blocks until its | |
2607 | * completion. | |
2608 | * | |
2609 | * Think twice before calling this function! It's very easy to get into | |
2610 | * trouble if you don't take great care. Either of the following situations | |
2611 | * will lead to deadlock: | |
2612 | * | |
2613 | * One of the work items currently on the workqueue needs to acquire | |
2614 | * a lock held by your code or its caller. | |
2615 | * | |
2616 | * Your code is running in the context of a work routine. | |
2617 | * | |
2618 | * They will be detected by lockdep when they occur, but the first might not | |
2619 | * occur very often. It depends on what work items are on the workqueue and | |
2620 | * what locks they need, which you have no control over. | |
2621 | * | |
2622 | * In most situations flushing the entire workqueue is overkill; you merely | |
2623 | * need to know that a particular work item isn't queued and isn't running. | |
2624 | * In such cases you should use cancel_delayed_work_sync() or | |
2625 | * cancel_work_sync() instead. | |
2626 | */ | |
1da177e4 LT |
2627 | void flush_scheduled_work(void) |
2628 | { | |
d320c038 | 2629 | flush_workqueue(system_wq); |
1da177e4 | 2630 | } |
ae90dd5d | 2631 | EXPORT_SYMBOL(flush_scheduled_work); |
1da177e4 | 2632 | |
1fa44eca JB |
2633 | /** |
2634 | * execute_in_process_context - reliably execute the routine with user context | |
2635 | * @fn: the function to execute | |
1fa44eca JB |
2636 | * @ew: guaranteed storage for the execute work structure (must |
2637 | * be available when the work executes) | |
2638 | * | |
2639 | * Executes the function immediately if process context is available, | |
2640 | * otherwise schedules the function for delayed execution. | |
2641 | * | |
2642 | * Returns: 0 - function was executed | |
2643 | * 1 - function was scheduled for execution | |
2644 | */ | |
65f27f38 | 2645 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
1fa44eca JB |
2646 | { |
2647 | if (!in_interrupt()) { | |
65f27f38 | 2648 | fn(&ew->work); |
1fa44eca JB |
2649 | return 0; |
2650 | } | |
2651 | ||
65f27f38 | 2652 | INIT_WORK(&ew->work, fn); |
1fa44eca JB |
2653 | schedule_work(&ew->work); |
2654 | ||
2655 | return 1; | |
2656 | } | |
2657 | EXPORT_SYMBOL_GPL(execute_in_process_context); | |
2658 | ||
1da177e4 LT |
2659 | int keventd_up(void) |
2660 | { | |
d320c038 | 2661 | return system_wq != NULL; |
1da177e4 LT |
2662 | } |
2663 | ||
bdbc5dd7 | 2664 | static int alloc_cwqs(struct workqueue_struct *wq) |
0f900049 | 2665 | { |
65a64464 | 2666 | /* |
0f900049 TH |
2667 | * cwqs are forced aligned according to WORK_STRUCT_FLAG_BITS. |
2668 | * Make sure that the alignment isn't lower than that of | |
2669 | * unsigned long long. | |
65a64464 | 2670 | */ |
0f900049 TH |
2671 | const size_t size = sizeof(struct cpu_workqueue_struct); |
2672 | const size_t align = max_t(size_t, 1 << WORK_STRUCT_FLAG_BITS, | |
2673 | __alignof__(unsigned long long)); | |
931ac77e TH |
2674 | #ifdef CONFIG_SMP |
2675 | bool percpu = !(wq->flags & WQ_UNBOUND); | |
2676 | #else | |
2677 | bool percpu = false; | |
2678 | #endif | |
65a64464 | 2679 | |
931ac77e | 2680 | if (percpu) |
f3421797 | 2681 | wq->cpu_wq.pcpu = __alloc_percpu(size, align); |
931ac77e | 2682 | else { |
f3421797 TH |
2683 | void *ptr; |
2684 | ||
2685 | /* | |
2686 | * Allocate enough room to align cwq and put an extra | |
2687 | * pointer at the end pointing back to the originally | |
2688 | * allocated pointer which will be used for free. | |
2689 | */ | |
2690 | ptr = kzalloc(size + align + sizeof(void *), GFP_KERNEL); | |
2691 | if (ptr) { | |
2692 | wq->cpu_wq.single = PTR_ALIGN(ptr, align); | |
2693 | *(void **)(wq->cpu_wq.single + 1) = ptr; | |
2694 | } | |
bdbc5dd7 | 2695 | } |
f3421797 | 2696 | |
0f900049 | 2697 | /* just in case, make sure it's actually aligned */ |
bdbc5dd7 TH |
2698 | BUG_ON(!IS_ALIGNED(wq->cpu_wq.v, align)); |
2699 | return wq->cpu_wq.v ? 0 : -ENOMEM; | |
0f900049 TH |
2700 | } |
2701 | ||
bdbc5dd7 | 2702 | static void free_cwqs(struct workqueue_struct *wq) |
0f900049 | 2703 | { |
931ac77e TH |
2704 | #ifdef CONFIG_SMP |
2705 | bool percpu = !(wq->flags & WQ_UNBOUND); | |
2706 | #else | |
2707 | bool percpu = false; | |
2708 | #endif | |
2709 | ||
2710 | if (percpu) | |
f3421797 TH |
2711 | free_percpu(wq->cpu_wq.pcpu); |
2712 | else if (wq->cpu_wq.single) { | |
2713 | /* the pointer to free is stored right after the cwq */ | |
bdbc5dd7 | 2714 | kfree(*(void **)(wq->cpu_wq.single + 1)); |
f3421797 | 2715 | } |
0f900049 TH |
2716 | } |
2717 | ||
f3421797 TH |
2718 | static int wq_clamp_max_active(int max_active, unsigned int flags, |
2719 | const char *name) | |
b71ab8c2 | 2720 | { |
f3421797 TH |
2721 | int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; |
2722 | ||
2723 | if (max_active < 1 || max_active > lim) | |
b71ab8c2 TH |
2724 | printk(KERN_WARNING "workqueue: max_active %d requested for %s " |
2725 | "is out of range, clamping between %d and %d\n", | |
f3421797 | 2726 | max_active, name, 1, lim); |
b71ab8c2 | 2727 | |
f3421797 | 2728 | return clamp_val(max_active, 1, lim); |
b71ab8c2 TH |
2729 | } |
2730 | ||
d320c038 TH |
2731 | struct workqueue_struct *__alloc_workqueue_key(const char *name, |
2732 | unsigned int flags, | |
2733 | int max_active, | |
2734 | struct lock_class_key *key, | |
2735 | const char *lock_name) | |
1da177e4 | 2736 | { |
1da177e4 | 2737 | struct workqueue_struct *wq; |
c34056a3 | 2738 | unsigned int cpu; |
1da177e4 | 2739 | |
f3421797 TH |
2740 | /* |
2741 | * Unbound workqueues aren't concurrency managed and should be | |
2742 | * dispatched to workers immediately. | |
2743 | */ | |
2744 | if (flags & WQ_UNBOUND) | |
2745 | flags |= WQ_HIGHPRI; | |
2746 | ||
d320c038 | 2747 | max_active = max_active ?: WQ_DFL_ACTIVE; |
f3421797 | 2748 | max_active = wq_clamp_max_active(max_active, flags, name); |
1e19ffc6 | 2749 | |
3af24433 ON |
2750 | wq = kzalloc(sizeof(*wq), GFP_KERNEL); |
2751 | if (!wq) | |
4690c4ab | 2752 | goto err; |
3af24433 | 2753 | |
97e37d7b | 2754 | wq->flags = flags; |
a0a1a5fd | 2755 | wq->saved_max_active = max_active; |
73f53c4a TH |
2756 | mutex_init(&wq->flush_mutex); |
2757 | atomic_set(&wq->nr_cwqs_to_flush, 0); | |
2758 | INIT_LIST_HEAD(&wq->flusher_queue); | |
2759 | INIT_LIST_HEAD(&wq->flusher_overflow); | |
502ca9d8 | 2760 | |
3af24433 | 2761 | wq->name = name; |
eb13ba87 | 2762 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
cce1a165 | 2763 | INIT_LIST_HEAD(&wq->list); |
3af24433 | 2764 | |
bdbc5dd7 TH |
2765 | if (alloc_cwqs(wq) < 0) |
2766 | goto err; | |
2767 | ||
f3421797 | 2768 | for_each_cwq_cpu(cpu, wq) { |
1537663f | 2769 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
8b03ae3c | 2770 | struct global_cwq *gcwq = get_gcwq(cpu); |
1537663f | 2771 | |
0f900049 | 2772 | BUG_ON((unsigned long)cwq & WORK_STRUCT_FLAG_MASK); |
8b03ae3c | 2773 | cwq->gcwq = gcwq; |
c34056a3 | 2774 | cwq->wq = wq; |
73f53c4a | 2775 | cwq->flush_color = -1; |
1e19ffc6 | 2776 | cwq->max_active = max_active; |
1e19ffc6 | 2777 | INIT_LIST_HEAD(&cwq->delayed_works); |
e22bee78 | 2778 | } |
1537663f | 2779 | |
e22bee78 TH |
2780 | if (flags & WQ_RESCUER) { |
2781 | struct worker *rescuer; | |
2782 | ||
f2e005aa | 2783 | if (!alloc_mayday_mask(&wq->mayday_mask, GFP_KERNEL)) |
e22bee78 TH |
2784 | goto err; |
2785 | ||
2786 | wq->rescuer = rescuer = alloc_worker(); | |
2787 | if (!rescuer) | |
2788 | goto err; | |
2789 | ||
2790 | rescuer->task = kthread_create(rescuer_thread, wq, "%s", name); | |
2791 | if (IS_ERR(rescuer->task)) | |
2792 | goto err; | |
2793 | ||
2794 | wq->rescuer = rescuer; | |
2795 | rescuer->task->flags |= PF_THREAD_BOUND; | |
2796 | wake_up_process(rescuer->task); | |
3af24433 ON |
2797 | } |
2798 | ||
a0a1a5fd TH |
2799 | /* |
2800 | * workqueue_lock protects global freeze state and workqueues | |
2801 | * list. Grab it, set max_active accordingly and add the new | |
2802 | * workqueue to workqueues list. | |
2803 | */ | |
1537663f | 2804 | spin_lock(&workqueue_lock); |
a0a1a5fd TH |
2805 | |
2806 | if (workqueue_freezing && wq->flags & WQ_FREEZEABLE) | |
f3421797 | 2807 | for_each_cwq_cpu(cpu, wq) |
a0a1a5fd TH |
2808 | get_cwq(cpu, wq)->max_active = 0; |
2809 | ||
1537663f | 2810 | list_add(&wq->list, &workqueues); |
a0a1a5fd | 2811 | |
1537663f TH |
2812 | spin_unlock(&workqueue_lock); |
2813 | ||
3af24433 | 2814 | return wq; |
4690c4ab TH |
2815 | err: |
2816 | if (wq) { | |
bdbc5dd7 | 2817 | free_cwqs(wq); |
f2e005aa | 2818 | free_mayday_mask(wq->mayday_mask); |
e22bee78 | 2819 | kfree(wq->rescuer); |
4690c4ab TH |
2820 | kfree(wq); |
2821 | } | |
2822 | return NULL; | |
3af24433 | 2823 | } |
d320c038 | 2824 | EXPORT_SYMBOL_GPL(__alloc_workqueue_key); |
1da177e4 | 2825 | |
3af24433 ON |
2826 | /** |
2827 | * destroy_workqueue - safely terminate a workqueue | |
2828 | * @wq: target workqueue | |
2829 | * | |
2830 | * Safely destroy a workqueue. All work currently pending will be done first. | |
2831 | */ | |
2832 | void destroy_workqueue(struct workqueue_struct *wq) | |
2833 | { | |
c8e55f36 | 2834 | unsigned int cpu; |
3af24433 | 2835 | |
a0a1a5fd TH |
2836 | flush_workqueue(wq); |
2837 | ||
2838 | /* | |
2839 | * wq list is used to freeze wq, remove from list after | |
2840 | * flushing is complete in case freeze races us. | |
2841 | */ | |
95402b38 | 2842 | spin_lock(&workqueue_lock); |
b1f4ec17 | 2843 | list_del(&wq->list); |
95402b38 | 2844 | spin_unlock(&workqueue_lock); |
3af24433 | 2845 | |
e22bee78 | 2846 | /* sanity check */ |
f3421797 | 2847 | for_each_cwq_cpu(cpu, wq) { |
73f53c4a TH |
2848 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
2849 | int i; | |
2850 | ||
73f53c4a TH |
2851 | for (i = 0; i < WORK_NR_COLORS; i++) |
2852 | BUG_ON(cwq->nr_in_flight[i]); | |
1e19ffc6 TH |
2853 | BUG_ON(cwq->nr_active); |
2854 | BUG_ON(!list_empty(&cwq->delayed_works)); | |
73f53c4a | 2855 | } |
9b41ea72 | 2856 | |
e22bee78 TH |
2857 | if (wq->flags & WQ_RESCUER) { |
2858 | kthread_stop(wq->rescuer->task); | |
f2e005aa | 2859 | free_mayday_mask(wq->mayday_mask); |
e22bee78 TH |
2860 | } |
2861 | ||
bdbc5dd7 | 2862 | free_cwqs(wq); |
3af24433 ON |
2863 | kfree(wq); |
2864 | } | |
2865 | EXPORT_SYMBOL_GPL(destroy_workqueue); | |
2866 | ||
dcd989cb TH |
2867 | /** |
2868 | * workqueue_set_max_active - adjust max_active of a workqueue | |
2869 | * @wq: target workqueue | |
2870 | * @max_active: new max_active value. | |
2871 | * | |
2872 | * Set max_active of @wq to @max_active. | |
2873 | * | |
2874 | * CONTEXT: | |
2875 | * Don't call from IRQ context. | |
2876 | */ | |
2877 | void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) | |
2878 | { | |
2879 | unsigned int cpu; | |
2880 | ||
f3421797 | 2881 | max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); |
dcd989cb TH |
2882 | |
2883 | spin_lock(&workqueue_lock); | |
2884 | ||
2885 | wq->saved_max_active = max_active; | |
2886 | ||
f3421797 | 2887 | for_each_cwq_cpu(cpu, wq) { |
dcd989cb TH |
2888 | struct global_cwq *gcwq = get_gcwq(cpu); |
2889 | ||
2890 | spin_lock_irq(&gcwq->lock); | |
2891 | ||
2892 | if (!(wq->flags & WQ_FREEZEABLE) || | |
2893 | !(gcwq->flags & GCWQ_FREEZING)) | |
2894 | get_cwq(gcwq->cpu, wq)->max_active = max_active; | |
9bfb1839 | 2895 | |
dcd989cb | 2896 | spin_unlock_irq(&gcwq->lock); |
65a64464 | 2897 | } |
93981800 | 2898 | |
dcd989cb | 2899 | spin_unlock(&workqueue_lock); |
15316ba8 | 2900 | } |
dcd989cb | 2901 | EXPORT_SYMBOL_GPL(workqueue_set_max_active); |
15316ba8 | 2902 | |
eef6a7d5 | 2903 | /** |
dcd989cb TH |
2904 | * workqueue_congested - test whether a workqueue is congested |
2905 | * @cpu: CPU in question | |
2906 | * @wq: target workqueue | |
eef6a7d5 | 2907 | * |
dcd989cb TH |
2908 | * Test whether @wq's cpu workqueue for @cpu is congested. There is |
2909 | * no synchronization around this function and the test result is | |
2910 | * unreliable and only useful as advisory hints or for debugging. | |
eef6a7d5 | 2911 | * |
dcd989cb TH |
2912 | * RETURNS: |
2913 | * %true if congested, %false otherwise. | |
eef6a7d5 | 2914 | */ |
dcd989cb | 2915 | bool workqueue_congested(unsigned int cpu, struct workqueue_struct *wq) |
1da177e4 | 2916 | { |
dcd989cb TH |
2917 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); |
2918 | ||
2919 | return !list_empty(&cwq->delayed_works); | |
1da177e4 | 2920 | } |
dcd989cb | 2921 | EXPORT_SYMBOL_GPL(workqueue_congested); |
1da177e4 | 2922 | |
1fa44eca | 2923 | /** |
dcd989cb TH |
2924 | * work_cpu - return the last known associated cpu for @work |
2925 | * @work: the work of interest | |
1fa44eca | 2926 | * |
dcd989cb | 2927 | * RETURNS: |
bdbc5dd7 | 2928 | * CPU number if @work was ever queued. WORK_CPU_NONE otherwise. |
1fa44eca | 2929 | */ |
dcd989cb | 2930 | unsigned int work_cpu(struct work_struct *work) |
1fa44eca | 2931 | { |
dcd989cb | 2932 | struct global_cwq *gcwq = get_work_gcwq(work); |
1fa44eca | 2933 | |
bdbc5dd7 | 2934 | return gcwq ? gcwq->cpu : WORK_CPU_NONE; |
1fa44eca | 2935 | } |
dcd989cb | 2936 | EXPORT_SYMBOL_GPL(work_cpu); |
1fa44eca | 2937 | |
dcd989cb TH |
2938 | /** |
2939 | * work_busy - test whether a work is currently pending or running | |
2940 | * @work: the work to be tested | |
2941 | * | |
2942 | * Test whether @work is currently pending or running. There is no | |
2943 | * synchronization around this function and the test result is | |
2944 | * unreliable and only useful as advisory hints or for debugging. | |
2945 | * Especially for reentrant wqs, the pending state might hide the | |
2946 | * running state. | |
2947 | * | |
2948 | * RETURNS: | |
2949 | * OR'd bitmask of WORK_BUSY_* bits. | |
2950 | */ | |
2951 | unsigned int work_busy(struct work_struct *work) | |
1da177e4 | 2952 | { |
dcd989cb TH |
2953 | struct global_cwq *gcwq = get_work_gcwq(work); |
2954 | unsigned long flags; | |
2955 | unsigned int ret = 0; | |
1da177e4 | 2956 | |
dcd989cb TH |
2957 | if (!gcwq) |
2958 | return false; | |
1da177e4 | 2959 | |
dcd989cb | 2960 | spin_lock_irqsave(&gcwq->lock, flags); |
1da177e4 | 2961 | |
dcd989cb TH |
2962 | if (work_pending(work)) |
2963 | ret |= WORK_BUSY_PENDING; | |
2964 | if (find_worker_executing_work(gcwq, work)) | |
2965 | ret |= WORK_BUSY_RUNNING; | |
1da177e4 | 2966 | |
dcd989cb | 2967 | spin_unlock_irqrestore(&gcwq->lock, flags); |
1da177e4 | 2968 | |
dcd989cb | 2969 | return ret; |
1da177e4 | 2970 | } |
dcd989cb | 2971 | EXPORT_SYMBOL_GPL(work_busy); |
1da177e4 | 2972 | |
db7bccf4 TH |
2973 | /* |
2974 | * CPU hotplug. | |
2975 | * | |
e22bee78 TH |
2976 | * There are two challenges in supporting CPU hotplug. Firstly, there |
2977 | * are a lot of assumptions on strong associations among work, cwq and | |
2978 | * gcwq which make migrating pending and scheduled works very | |
2979 | * difficult to implement without impacting hot paths. Secondly, | |
2980 | * gcwqs serve mix of short, long and very long running works making | |
2981 | * blocked draining impractical. | |
2982 | * | |
2983 | * This is solved by allowing a gcwq to be detached from CPU, running | |
2984 | * it with unbound (rogue) workers and allowing it to be reattached | |
2985 | * later if the cpu comes back online. A separate thread is created | |
2986 | * to govern a gcwq in such state and is called the trustee of the | |
2987 | * gcwq. | |
db7bccf4 TH |
2988 | * |
2989 | * Trustee states and their descriptions. | |
2990 | * | |
2991 | * START Command state used on startup. On CPU_DOWN_PREPARE, a | |
2992 | * new trustee is started with this state. | |
2993 | * | |
2994 | * IN_CHARGE Once started, trustee will enter this state after | |
e22bee78 TH |
2995 | * assuming the manager role and making all existing |
2996 | * workers rogue. DOWN_PREPARE waits for trustee to | |
2997 | * enter this state. After reaching IN_CHARGE, trustee | |
2998 | * tries to execute the pending worklist until it's empty | |
2999 | * and the state is set to BUTCHER, or the state is set | |
3000 | * to RELEASE. | |
db7bccf4 TH |
3001 | * |
3002 | * BUTCHER Command state which is set by the cpu callback after | |
3003 | * the cpu has went down. Once this state is set trustee | |
3004 | * knows that there will be no new works on the worklist | |
3005 | * and once the worklist is empty it can proceed to | |
3006 | * killing idle workers. | |
3007 | * | |
3008 | * RELEASE Command state which is set by the cpu callback if the | |
3009 | * cpu down has been canceled or it has come online | |
3010 | * again. After recognizing this state, trustee stops | |
e22bee78 TH |
3011 | * trying to drain or butcher and clears ROGUE, rebinds |
3012 | * all remaining workers back to the cpu and releases | |
3013 | * manager role. | |
db7bccf4 TH |
3014 | * |
3015 | * DONE Trustee will enter this state after BUTCHER or RELEASE | |
3016 | * is complete. | |
3017 | * | |
3018 | * trustee CPU draining | |
3019 | * took over down complete | |
3020 | * START -----------> IN_CHARGE -----------> BUTCHER -----------> DONE | |
3021 | * | | ^ | |
3022 | * | CPU is back online v return workers | | |
3023 | * ----------------> RELEASE -------------- | |
3024 | */ | |
1da177e4 | 3025 | |
db7bccf4 TH |
3026 | /** |
3027 | * trustee_wait_event_timeout - timed event wait for trustee | |
3028 | * @cond: condition to wait for | |
3029 | * @timeout: timeout in jiffies | |
3030 | * | |
3031 | * wait_event_timeout() for trustee to use. Handles locking and | |
3032 | * checks for RELEASE request. | |
3033 | * | |
3034 | * CONTEXT: | |
3035 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed | |
3036 | * multiple times. To be used by trustee. | |
3037 | * | |
3038 | * RETURNS: | |
3039 | * Positive indicating left time if @cond is satisfied, 0 if timed | |
3040 | * out, -1 if canceled. | |
3041 | */ | |
3042 | #define trustee_wait_event_timeout(cond, timeout) ({ \ | |
3043 | long __ret = (timeout); \ | |
3044 | while (!((cond) || (gcwq->trustee_state == TRUSTEE_RELEASE)) && \ | |
3045 | __ret) { \ | |
3046 | spin_unlock_irq(&gcwq->lock); \ | |
3047 | __wait_event_timeout(gcwq->trustee_wait, (cond) || \ | |
3048 | (gcwq->trustee_state == TRUSTEE_RELEASE), \ | |
3049 | __ret); \ | |
3050 | spin_lock_irq(&gcwq->lock); \ | |
3051 | } \ | |
3052 | gcwq->trustee_state == TRUSTEE_RELEASE ? -1 : (__ret); \ | |
3053 | }) | |
3af24433 | 3054 | |
db7bccf4 TH |
3055 | /** |
3056 | * trustee_wait_event - event wait for trustee | |
3057 | * @cond: condition to wait for | |
3058 | * | |
3059 | * wait_event() for trustee to use. Automatically handles locking and | |
3060 | * checks for CANCEL request. | |
3061 | * | |
3062 | * CONTEXT: | |
3063 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed | |
3064 | * multiple times. To be used by trustee. | |
3065 | * | |
3066 | * RETURNS: | |
3067 | * 0 if @cond is satisfied, -1 if canceled. | |
3068 | */ | |
3069 | #define trustee_wait_event(cond) ({ \ | |
3070 | long __ret1; \ | |
3071 | __ret1 = trustee_wait_event_timeout(cond, MAX_SCHEDULE_TIMEOUT);\ | |
3072 | __ret1 < 0 ? -1 : 0; \ | |
3073 | }) | |
1da177e4 | 3074 | |
db7bccf4 | 3075 | static int __cpuinit trustee_thread(void *__gcwq) |
3af24433 | 3076 | { |
db7bccf4 TH |
3077 | struct global_cwq *gcwq = __gcwq; |
3078 | struct worker *worker; | |
e22bee78 | 3079 | struct work_struct *work; |
db7bccf4 | 3080 | struct hlist_node *pos; |
e22bee78 | 3081 | long rc; |
db7bccf4 | 3082 | int i; |
3af24433 | 3083 | |
db7bccf4 TH |
3084 | BUG_ON(gcwq->cpu != smp_processor_id()); |
3085 | ||
3086 | spin_lock_irq(&gcwq->lock); | |
3af24433 | 3087 | /* |
e22bee78 TH |
3088 | * Claim the manager position and make all workers rogue. |
3089 | * Trustee must be bound to the target cpu and can't be | |
3090 | * cancelled. | |
3af24433 | 3091 | */ |
db7bccf4 | 3092 | BUG_ON(gcwq->cpu != smp_processor_id()); |
e22bee78 TH |
3093 | rc = trustee_wait_event(!(gcwq->flags & GCWQ_MANAGING_WORKERS)); |
3094 | BUG_ON(rc < 0); | |
3af24433 | 3095 | |
e22bee78 | 3096 | gcwq->flags |= GCWQ_MANAGING_WORKERS; |
e1d8aa9f | 3097 | |
db7bccf4 | 3098 | list_for_each_entry(worker, &gcwq->idle_list, entry) |
cb444766 | 3099 | worker->flags |= WORKER_ROGUE; |
3af24433 | 3100 | |
db7bccf4 | 3101 | for_each_busy_worker(worker, i, pos, gcwq) |
cb444766 | 3102 | worker->flags |= WORKER_ROGUE; |
06ba38a9 | 3103 | |
e22bee78 TH |
3104 | /* |
3105 | * Call schedule() so that we cross rq->lock and thus can | |
3106 | * guarantee sched callbacks see the rogue flag. This is | |
3107 | * necessary as scheduler callbacks may be invoked from other | |
3108 | * cpus. | |
3109 | */ | |
3110 | spin_unlock_irq(&gcwq->lock); | |
3111 | schedule(); | |
3112 | spin_lock_irq(&gcwq->lock); | |
06ba38a9 | 3113 | |
e22bee78 | 3114 | /* |
cb444766 TH |
3115 | * Sched callbacks are disabled now. Zap nr_running. After |
3116 | * this, nr_running stays zero and need_more_worker() and | |
3117 | * keep_working() are always true as long as the worklist is | |
3118 | * not empty. | |
e22bee78 | 3119 | */ |
cb444766 | 3120 | atomic_set(get_gcwq_nr_running(gcwq->cpu), 0); |
1da177e4 | 3121 | |
e22bee78 TH |
3122 | spin_unlock_irq(&gcwq->lock); |
3123 | del_timer_sync(&gcwq->idle_timer); | |
3124 | spin_lock_irq(&gcwq->lock); | |
3af24433 | 3125 | |
db7bccf4 TH |
3126 | /* |
3127 | * We're now in charge. Notify and proceed to drain. We need | |
3128 | * to keep the gcwq running during the whole CPU down | |
3129 | * procedure as other cpu hotunplug callbacks may need to | |
3130 | * flush currently running tasks. | |
3131 | */ | |
3132 | gcwq->trustee_state = TRUSTEE_IN_CHARGE; | |
3133 | wake_up_all(&gcwq->trustee_wait); | |
3af24433 | 3134 | |
db7bccf4 TH |
3135 | /* |
3136 | * The original cpu is in the process of dying and may go away | |
3137 | * anytime now. When that happens, we and all workers would | |
e22bee78 TH |
3138 | * be migrated to other cpus. Try draining any left work. We |
3139 | * want to get it over with ASAP - spam rescuers, wake up as | |
3140 | * many idlers as necessary and create new ones till the | |
3141 | * worklist is empty. Note that if the gcwq is frozen, there | |
3142 | * may be frozen works in freezeable cwqs. Don't declare | |
3143 | * completion while frozen. | |
db7bccf4 TH |
3144 | */ |
3145 | while (gcwq->nr_workers != gcwq->nr_idle || | |
3146 | gcwq->flags & GCWQ_FREEZING || | |
3147 | gcwq->trustee_state == TRUSTEE_IN_CHARGE) { | |
e22bee78 TH |
3148 | int nr_works = 0; |
3149 | ||
3150 | list_for_each_entry(work, &gcwq->worklist, entry) { | |
3151 | send_mayday(work); | |
3152 | nr_works++; | |
3153 | } | |
3af24433 | 3154 | |
e22bee78 TH |
3155 | list_for_each_entry(worker, &gcwq->idle_list, entry) { |
3156 | if (!nr_works--) | |
3157 | break; | |
3158 | wake_up_process(worker->task); | |
3159 | } | |
3160 | ||
3161 | if (need_to_create_worker(gcwq)) { | |
3162 | spin_unlock_irq(&gcwq->lock); | |
3163 | worker = create_worker(gcwq, false); | |
3164 | spin_lock_irq(&gcwq->lock); | |
3165 | if (worker) { | |
cb444766 | 3166 | worker->flags |= WORKER_ROGUE; |
e22bee78 TH |
3167 | start_worker(worker); |
3168 | } | |
1da177e4 | 3169 | } |
3af24433 | 3170 | |
db7bccf4 TH |
3171 | /* give a breather */ |
3172 | if (trustee_wait_event_timeout(false, TRUSTEE_COOLDOWN) < 0) | |
3173 | break; | |
3af24433 | 3174 | } |
1da177e4 | 3175 | |
14441960 | 3176 | /* |
e22bee78 TH |
3177 | * Either all works have been scheduled and cpu is down, or |
3178 | * cpu down has already been canceled. Wait for and butcher | |
3179 | * all workers till we're canceled. | |
14441960 | 3180 | */ |
e22bee78 TH |
3181 | do { |
3182 | rc = trustee_wait_event(!list_empty(&gcwq->idle_list)); | |
3183 | while (!list_empty(&gcwq->idle_list)) | |
3184 | destroy_worker(list_first_entry(&gcwq->idle_list, | |
3185 | struct worker, entry)); | |
3186 | } while (gcwq->nr_workers && rc >= 0); | |
4e6045f1 | 3187 | |
14441960 | 3188 | /* |
e22bee78 TH |
3189 | * At this point, either draining has completed and no worker |
3190 | * is left, or cpu down has been canceled or the cpu is being | |
3191 | * brought back up. There shouldn't be any idle one left. | |
3192 | * Tell the remaining busy ones to rebind once it finishes the | |
3193 | * currently scheduled works by scheduling the rebind_work. | |
14441960 | 3194 | */ |
e22bee78 TH |
3195 | WARN_ON(!list_empty(&gcwq->idle_list)); |
3196 | ||
3197 | for_each_busy_worker(worker, i, pos, gcwq) { | |
3198 | struct work_struct *rebind_work = &worker->rebind_work; | |
3199 | ||
3200 | /* | |
3201 | * Rebind_work may race with future cpu hotplug | |
3202 | * operations. Use a separate flag to mark that | |
3203 | * rebinding is scheduled. | |
3204 | */ | |
cb444766 TH |
3205 | worker->flags |= WORKER_REBIND; |
3206 | worker->flags &= ~WORKER_ROGUE; | |
e22bee78 TH |
3207 | |
3208 | /* queue rebind_work, wq doesn't matter, use the default one */ | |
3209 | if (test_and_set_bit(WORK_STRUCT_PENDING_BIT, | |
3210 | work_data_bits(rebind_work))) | |
3211 | continue; | |
3212 | ||
3213 | debug_work_activate(rebind_work); | |
d320c038 | 3214 | insert_work(get_cwq(gcwq->cpu, system_wq), rebind_work, |
e22bee78 TH |
3215 | worker->scheduled.next, |
3216 | work_color_to_flags(WORK_NO_COLOR)); | |
3217 | } | |
3218 | ||
3219 | /* relinquish manager role */ | |
3220 | gcwq->flags &= ~GCWQ_MANAGING_WORKERS; | |
3221 | ||
db7bccf4 TH |
3222 | /* notify completion */ |
3223 | gcwq->trustee = NULL; | |
3224 | gcwq->trustee_state = TRUSTEE_DONE; | |
3225 | wake_up_all(&gcwq->trustee_wait); | |
3226 | spin_unlock_irq(&gcwq->lock); | |
3227 | return 0; | |
3af24433 ON |
3228 | } |
3229 | ||
3230 | /** | |
db7bccf4 TH |
3231 | * wait_trustee_state - wait for trustee to enter the specified state |
3232 | * @gcwq: gcwq the trustee of interest belongs to | |
3233 | * @state: target state to wait for | |
3af24433 | 3234 | * |
db7bccf4 TH |
3235 | * Wait for the trustee to reach @state. DONE is already matched. |
3236 | * | |
3237 | * CONTEXT: | |
3238 | * spin_lock_irq(gcwq->lock) which may be released and regrabbed | |
3239 | * multiple times. To be used by cpu_callback. | |
3af24433 | 3240 | */ |
db7bccf4 | 3241 | static void __cpuinit wait_trustee_state(struct global_cwq *gcwq, int state) |
3af24433 | 3242 | { |
db7bccf4 TH |
3243 | if (!(gcwq->trustee_state == state || |
3244 | gcwq->trustee_state == TRUSTEE_DONE)) { | |
3245 | spin_unlock_irq(&gcwq->lock); | |
3246 | __wait_event(gcwq->trustee_wait, | |
3247 | gcwq->trustee_state == state || | |
3248 | gcwq->trustee_state == TRUSTEE_DONE); | |
3249 | spin_lock_irq(&gcwq->lock); | |
3250 | } | |
3af24433 | 3251 | } |
3af24433 ON |
3252 | |
3253 | static int __devinit workqueue_cpu_callback(struct notifier_block *nfb, | |
3254 | unsigned long action, | |
3255 | void *hcpu) | |
3256 | { | |
3257 | unsigned int cpu = (unsigned long)hcpu; | |
db7bccf4 TH |
3258 | struct global_cwq *gcwq = get_gcwq(cpu); |
3259 | struct task_struct *new_trustee = NULL; | |
e22bee78 | 3260 | struct worker *uninitialized_var(new_worker); |
db7bccf4 | 3261 | unsigned long flags; |
3af24433 | 3262 | |
8bb78442 RW |
3263 | action &= ~CPU_TASKS_FROZEN; |
3264 | ||
3af24433 | 3265 | switch (action) { |
db7bccf4 TH |
3266 | case CPU_DOWN_PREPARE: |
3267 | new_trustee = kthread_create(trustee_thread, gcwq, | |
3268 | "workqueue_trustee/%d\n", cpu); | |
3269 | if (IS_ERR(new_trustee)) | |
3270 | return notifier_from_errno(PTR_ERR(new_trustee)); | |
3271 | kthread_bind(new_trustee, cpu); | |
e22bee78 | 3272 | /* fall through */ |
3af24433 | 3273 | case CPU_UP_PREPARE: |
e22bee78 TH |
3274 | BUG_ON(gcwq->first_idle); |
3275 | new_worker = create_worker(gcwq, false); | |
3276 | if (!new_worker) { | |
3277 | if (new_trustee) | |
3278 | kthread_stop(new_trustee); | |
3279 | return NOTIFY_BAD; | |
3af24433 | 3280 | } |
1da177e4 LT |
3281 | } |
3282 | ||
db7bccf4 TH |
3283 | /* some are called w/ irq disabled, don't disturb irq status */ |
3284 | spin_lock_irqsave(&gcwq->lock, flags); | |
3af24433 | 3285 | |
00dfcaf7 | 3286 | switch (action) { |
db7bccf4 TH |
3287 | case CPU_DOWN_PREPARE: |
3288 | /* initialize trustee and tell it to acquire the gcwq */ | |
3289 | BUG_ON(gcwq->trustee || gcwq->trustee_state != TRUSTEE_DONE); | |
3290 | gcwq->trustee = new_trustee; | |
3291 | gcwq->trustee_state = TRUSTEE_START; | |
3292 | wake_up_process(gcwq->trustee); | |
3293 | wait_trustee_state(gcwq, TRUSTEE_IN_CHARGE); | |
e22bee78 TH |
3294 | /* fall through */ |
3295 | case CPU_UP_PREPARE: | |
3296 | BUG_ON(gcwq->first_idle); | |
3297 | gcwq->first_idle = new_worker; | |
3298 | break; | |
3299 | ||
3300 | case CPU_DYING: | |
3301 | /* | |
3302 | * Before this, the trustee and all workers except for | |
3303 | * the ones which are still executing works from | |
3304 | * before the last CPU down must be on the cpu. After | |
3305 | * this, they'll all be diasporas. | |
3306 | */ | |
3307 | gcwq->flags |= GCWQ_DISASSOCIATED; | |
db7bccf4 TH |
3308 | break; |
3309 | ||
3da1c84c | 3310 | case CPU_POST_DEAD: |
db7bccf4 | 3311 | gcwq->trustee_state = TRUSTEE_BUTCHER; |
e22bee78 TH |
3312 | /* fall through */ |
3313 | case CPU_UP_CANCELED: | |
3314 | destroy_worker(gcwq->first_idle); | |
3315 | gcwq->first_idle = NULL; | |
db7bccf4 TH |
3316 | break; |
3317 | ||
3318 | case CPU_DOWN_FAILED: | |
3319 | case CPU_ONLINE: | |
e22bee78 | 3320 | gcwq->flags &= ~GCWQ_DISASSOCIATED; |
db7bccf4 TH |
3321 | if (gcwq->trustee_state != TRUSTEE_DONE) { |
3322 | gcwq->trustee_state = TRUSTEE_RELEASE; | |
3323 | wake_up_process(gcwq->trustee); | |
3324 | wait_trustee_state(gcwq, TRUSTEE_DONE); | |
3af24433 | 3325 | } |
db7bccf4 | 3326 | |
e22bee78 TH |
3327 | /* |
3328 | * Trustee is done and there might be no worker left. | |
3329 | * Put the first_idle in and request a real manager to | |
3330 | * take a look. | |
3331 | */ | |
3332 | spin_unlock_irq(&gcwq->lock); | |
3333 | kthread_bind(gcwq->first_idle->task, cpu); | |
3334 | spin_lock_irq(&gcwq->lock); | |
3335 | gcwq->flags |= GCWQ_MANAGE_WORKERS; | |
3336 | start_worker(gcwq->first_idle); | |
3337 | gcwq->first_idle = NULL; | |
db7bccf4 | 3338 | break; |
00dfcaf7 ON |
3339 | } |
3340 | ||
db7bccf4 TH |
3341 | spin_unlock_irqrestore(&gcwq->lock, flags); |
3342 | ||
1537663f | 3343 | return notifier_from_errno(0); |
1da177e4 | 3344 | } |
1da177e4 | 3345 | |
2d3854a3 | 3346 | #ifdef CONFIG_SMP |
8ccad40d | 3347 | |
2d3854a3 | 3348 | struct work_for_cpu { |
6b44003e | 3349 | struct completion completion; |
2d3854a3 RR |
3350 | long (*fn)(void *); |
3351 | void *arg; | |
3352 | long ret; | |
3353 | }; | |
3354 | ||
6b44003e | 3355 | static int do_work_for_cpu(void *_wfc) |
2d3854a3 | 3356 | { |
6b44003e | 3357 | struct work_for_cpu *wfc = _wfc; |
2d3854a3 | 3358 | wfc->ret = wfc->fn(wfc->arg); |
6b44003e AM |
3359 | complete(&wfc->completion); |
3360 | return 0; | |
2d3854a3 RR |
3361 | } |
3362 | ||
3363 | /** | |
3364 | * work_on_cpu - run a function in user context on a particular cpu | |
3365 | * @cpu: the cpu to run on | |
3366 | * @fn: the function to run | |
3367 | * @arg: the function arg | |
3368 | * | |
31ad9081 RR |
3369 | * This will return the value @fn returns. |
3370 | * It is up to the caller to ensure that the cpu doesn't go offline. | |
6b44003e | 3371 | * The caller must not hold any locks which would prevent @fn from completing. |
2d3854a3 RR |
3372 | */ |
3373 | long work_on_cpu(unsigned int cpu, long (*fn)(void *), void *arg) | |
3374 | { | |
6b44003e AM |
3375 | struct task_struct *sub_thread; |
3376 | struct work_for_cpu wfc = { | |
3377 | .completion = COMPLETION_INITIALIZER_ONSTACK(wfc.completion), | |
3378 | .fn = fn, | |
3379 | .arg = arg, | |
3380 | }; | |
3381 | ||
3382 | sub_thread = kthread_create(do_work_for_cpu, &wfc, "work_for_cpu"); | |
3383 | if (IS_ERR(sub_thread)) | |
3384 | return PTR_ERR(sub_thread); | |
3385 | kthread_bind(sub_thread, cpu); | |
3386 | wake_up_process(sub_thread); | |
3387 | wait_for_completion(&wfc.completion); | |
2d3854a3 RR |
3388 | return wfc.ret; |
3389 | } | |
3390 | EXPORT_SYMBOL_GPL(work_on_cpu); | |
3391 | #endif /* CONFIG_SMP */ | |
3392 | ||
a0a1a5fd TH |
3393 | #ifdef CONFIG_FREEZER |
3394 | ||
3395 | /** | |
3396 | * freeze_workqueues_begin - begin freezing workqueues | |
3397 | * | |
3398 | * Start freezing workqueues. After this function returns, all | |
3399 | * freezeable workqueues will queue new works to their frozen_works | |
7e11629d | 3400 | * list instead of gcwq->worklist. |
a0a1a5fd TH |
3401 | * |
3402 | * CONTEXT: | |
8b03ae3c | 3403 | * Grabs and releases workqueue_lock and gcwq->lock's. |
a0a1a5fd TH |
3404 | */ |
3405 | void freeze_workqueues_begin(void) | |
3406 | { | |
a0a1a5fd TH |
3407 | unsigned int cpu; |
3408 | ||
3409 | spin_lock(&workqueue_lock); | |
3410 | ||
3411 | BUG_ON(workqueue_freezing); | |
3412 | workqueue_freezing = true; | |
3413 | ||
f3421797 | 3414 | for_each_gcwq_cpu(cpu) { |
8b03ae3c | 3415 | struct global_cwq *gcwq = get_gcwq(cpu); |
bdbc5dd7 | 3416 | struct workqueue_struct *wq; |
8b03ae3c TH |
3417 | |
3418 | spin_lock_irq(&gcwq->lock); | |
3419 | ||
db7bccf4 TH |
3420 | BUG_ON(gcwq->flags & GCWQ_FREEZING); |
3421 | gcwq->flags |= GCWQ_FREEZING; | |
3422 | ||
a0a1a5fd TH |
3423 | list_for_each_entry(wq, &workqueues, list) { |
3424 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
3425 | ||
f3421797 | 3426 | if (cwq && wq->flags & WQ_FREEZEABLE) |
a0a1a5fd | 3427 | cwq->max_active = 0; |
a0a1a5fd | 3428 | } |
8b03ae3c TH |
3429 | |
3430 | spin_unlock_irq(&gcwq->lock); | |
a0a1a5fd TH |
3431 | } |
3432 | ||
3433 | spin_unlock(&workqueue_lock); | |
3434 | } | |
3435 | ||
3436 | /** | |
3437 | * freeze_workqueues_busy - are freezeable workqueues still busy? | |
3438 | * | |
3439 | * Check whether freezing is complete. This function must be called | |
3440 | * between freeze_workqueues_begin() and thaw_workqueues(). | |
3441 | * | |
3442 | * CONTEXT: | |
3443 | * Grabs and releases workqueue_lock. | |
3444 | * | |
3445 | * RETURNS: | |
3446 | * %true if some freezeable workqueues are still busy. %false if | |
3447 | * freezing is complete. | |
3448 | */ | |
3449 | bool freeze_workqueues_busy(void) | |
3450 | { | |
a0a1a5fd TH |
3451 | unsigned int cpu; |
3452 | bool busy = false; | |
3453 | ||
3454 | spin_lock(&workqueue_lock); | |
3455 | ||
3456 | BUG_ON(!workqueue_freezing); | |
3457 | ||
f3421797 | 3458 | for_each_gcwq_cpu(cpu) { |
bdbc5dd7 | 3459 | struct workqueue_struct *wq; |
a0a1a5fd TH |
3460 | /* |
3461 | * nr_active is monotonically decreasing. It's safe | |
3462 | * to peek without lock. | |
3463 | */ | |
3464 | list_for_each_entry(wq, &workqueues, list) { | |
3465 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
3466 | ||
f3421797 | 3467 | if (!cwq || !(wq->flags & WQ_FREEZEABLE)) |
a0a1a5fd TH |
3468 | continue; |
3469 | ||
3470 | BUG_ON(cwq->nr_active < 0); | |
3471 | if (cwq->nr_active) { | |
3472 | busy = true; | |
3473 | goto out_unlock; | |
3474 | } | |
3475 | } | |
3476 | } | |
3477 | out_unlock: | |
3478 | spin_unlock(&workqueue_lock); | |
3479 | return busy; | |
3480 | } | |
3481 | ||
3482 | /** | |
3483 | * thaw_workqueues - thaw workqueues | |
3484 | * | |
3485 | * Thaw workqueues. Normal queueing is restored and all collected | |
7e11629d | 3486 | * frozen works are transferred to their respective gcwq worklists. |
a0a1a5fd TH |
3487 | * |
3488 | * CONTEXT: | |
8b03ae3c | 3489 | * Grabs and releases workqueue_lock and gcwq->lock's. |
a0a1a5fd TH |
3490 | */ |
3491 | void thaw_workqueues(void) | |
3492 | { | |
a0a1a5fd TH |
3493 | unsigned int cpu; |
3494 | ||
3495 | spin_lock(&workqueue_lock); | |
3496 | ||
3497 | if (!workqueue_freezing) | |
3498 | goto out_unlock; | |
3499 | ||
f3421797 | 3500 | for_each_gcwq_cpu(cpu) { |
8b03ae3c | 3501 | struct global_cwq *gcwq = get_gcwq(cpu); |
bdbc5dd7 | 3502 | struct workqueue_struct *wq; |
8b03ae3c TH |
3503 | |
3504 | spin_lock_irq(&gcwq->lock); | |
3505 | ||
db7bccf4 TH |
3506 | BUG_ON(!(gcwq->flags & GCWQ_FREEZING)); |
3507 | gcwq->flags &= ~GCWQ_FREEZING; | |
3508 | ||
a0a1a5fd TH |
3509 | list_for_each_entry(wq, &workqueues, list) { |
3510 | struct cpu_workqueue_struct *cwq = get_cwq(cpu, wq); | |
3511 | ||
f3421797 | 3512 | if (!cwq || !(wq->flags & WQ_FREEZEABLE)) |
a0a1a5fd TH |
3513 | continue; |
3514 | ||
a0a1a5fd TH |
3515 | /* restore max_active and repopulate worklist */ |
3516 | cwq->max_active = wq->saved_max_active; | |
3517 | ||
3518 | while (!list_empty(&cwq->delayed_works) && | |
3519 | cwq->nr_active < cwq->max_active) | |
3520 | cwq_activate_first_delayed(cwq); | |
a0a1a5fd | 3521 | } |
8b03ae3c | 3522 | |
e22bee78 TH |
3523 | wake_up_worker(gcwq); |
3524 | ||
8b03ae3c | 3525 | spin_unlock_irq(&gcwq->lock); |
a0a1a5fd TH |
3526 | } |
3527 | ||
3528 | workqueue_freezing = false; | |
3529 | out_unlock: | |
3530 | spin_unlock(&workqueue_lock); | |
3531 | } | |
3532 | #endif /* CONFIG_FREEZER */ | |
3533 | ||
6ee0578b | 3534 | static int __init init_workqueues(void) |
1da177e4 | 3535 | { |
c34056a3 | 3536 | unsigned int cpu; |
c8e55f36 | 3537 | int i; |
c34056a3 | 3538 | |
f6500947 | 3539 | cpu_notifier(workqueue_cpu_callback, CPU_PRI_WORKQUEUE); |
8b03ae3c TH |
3540 | |
3541 | /* initialize gcwqs */ | |
f3421797 | 3542 | for_each_gcwq_cpu(cpu) { |
8b03ae3c TH |
3543 | struct global_cwq *gcwq = get_gcwq(cpu); |
3544 | ||
3545 | spin_lock_init(&gcwq->lock); | |
7e11629d | 3546 | INIT_LIST_HEAD(&gcwq->worklist); |
8b03ae3c | 3547 | gcwq->cpu = cpu; |
f3421797 TH |
3548 | if (cpu == WORK_CPU_UNBOUND) |
3549 | gcwq->flags |= GCWQ_DISASSOCIATED; | |
8b03ae3c | 3550 | |
c8e55f36 TH |
3551 | INIT_LIST_HEAD(&gcwq->idle_list); |
3552 | for (i = 0; i < BUSY_WORKER_HASH_SIZE; i++) | |
3553 | INIT_HLIST_HEAD(&gcwq->busy_hash[i]); | |
3554 | ||
e22bee78 TH |
3555 | init_timer_deferrable(&gcwq->idle_timer); |
3556 | gcwq->idle_timer.function = idle_worker_timeout; | |
3557 | gcwq->idle_timer.data = (unsigned long)gcwq; | |
e7577c50 | 3558 | |
e22bee78 TH |
3559 | setup_timer(&gcwq->mayday_timer, gcwq_mayday_timeout, |
3560 | (unsigned long)gcwq); | |
3561 | ||
8b03ae3c | 3562 | ida_init(&gcwq->worker_ida); |
db7bccf4 TH |
3563 | |
3564 | gcwq->trustee_state = TRUSTEE_DONE; | |
3565 | init_waitqueue_head(&gcwq->trustee_wait); | |
8b03ae3c TH |
3566 | } |
3567 | ||
e22bee78 | 3568 | /* create the initial worker */ |
f3421797 | 3569 | for_each_online_gcwq_cpu(cpu) { |
e22bee78 TH |
3570 | struct global_cwq *gcwq = get_gcwq(cpu); |
3571 | struct worker *worker; | |
3572 | ||
3573 | worker = create_worker(gcwq, true); | |
3574 | BUG_ON(!worker); | |
3575 | spin_lock_irq(&gcwq->lock); | |
3576 | start_worker(worker); | |
3577 | spin_unlock_irq(&gcwq->lock); | |
3578 | } | |
3579 | ||
d320c038 TH |
3580 | system_wq = alloc_workqueue("events", 0, 0); |
3581 | system_long_wq = alloc_workqueue("events_long", 0, 0); | |
3582 | system_nrt_wq = alloc_workqueue("events_nrt", WQ_NON_REENTRANT, 0); | |
f3421797 TH |
3583 | system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, |
3584 | WQ_UNBOUND_MAX_ACTIVE); | |
d320c038 | 3585 | BUG_ON(!system_wq || !system_long_wq || !system_nrt_wq); |
6ee0578b | 3586 | return 0; |
1da177e4 | 3587 | } |
6ee0578b | 3588 | early_initcall(init_workqueues); |