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Source at commit fbf123cd4cc0c097fe9a99c90109ebb2a5e94a50 created 10 years 3 months ago. By Lars-Peter Clausen, dma: jz4740: Dequeue descriptor from active list before completing it | |
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1 | /* |
2 | * kernel/workqueue.c - generic async execution with shared worker pool |
3 | * |
4 | * Copyright (C) 2002 Ingo Molnar |
5 | * |
6 | * Derived from the taskqueue/keventd code by: |
7 | * David Woodhouse <dwmw2@infradead.org> |
8 | * Andrew Morton |
9 | * Kai Petzke <wpp@marie.physik.tu-berlin.de> |
10 | * Theodore Ts'o <tytso@mit.edu> |
11 | * |
12 | * Made to use alloc_percpu by Christoph Lameter. |
13 | * |
14 | * Copyright (C) 2010 SUSE Linux Products GmbH |
15 | * Copyright (C) 2010 Tejun Heo <tj@kernel.org> |
16 | * |
17 | * This is the generic async execution mechanism. Work items as are |
18 | * executed in process context. The worker pool is shared and |
19 | * automatically managed. There are two worker pools for each CPU (one for |
20 | * normal work items and the other for high priority ones) and some extra |
21 | * pools for workqueues which are not bound to any specific CPU - the |
22 | * number of these backing pools is dynamic. |
23 | * |
24 | * Please read Documentation/workqueue.txt for details. |
25 | */ |
26 | |
27 | #include <linux/export.h> |
28 | #include <linux/kernel.h> |
29 | #include <linux/sched.h> |
30 | #include <linux/init.h> |
31 | #include <linux/signal.h> |
32 | #include <linux/completion.h> |
33 | #include <linux/workqueue.h> |
34 | #include <linux/slab.h> |
35 | #include <linux/cpu.h> |
36 | #include <linux/notifier.h> |
37 | #include <linux/kthread.h> |
38 | #include <linux/hardirq.h> |
39 | #include <linux/mempolicy.h> |
40 | #include <linux/freezer.h> |
41 | #include <linux/kallsyms.h> |
42 | #include <linux/debug_locks.h> |
43 | #include <linux/lockdep.h> |
44 | #include <linux/idr.h> |
45 | #include <linux/jhash.h> |
46 | #include <linux/hashtable.h> |
47 | #include <linux/rculist.h> |
48 | #include <linux/nodemask.h> |
49 | #include <linux/moduleparam.h> |
50 | #include <linux/uaccess.h> |
51 | |
52 | #include "workqueue_internal.h" |
53 | |
54 | enum { |
55 | /* |
56 | * worker_pool flags |
57 | * |
58 | * A bound pool is either associated or disassociated with its CPU. |
59 | * While associated (!DISASSOCIATED), all workers are bound to the |
60 | * CPU and none has %WORKER_UNBOUND set and concurrency management |
61 | * is in effect. |
62 | * |
63 | * While DISASSOCIATED, the cpu may be offline and all workers have |
64 | * %WORKER_UNBOUND set and concurrency management disabled, and may |
65 | * be executing on any CPU. The pool behaves as an unbound one. |
66 | * |
67 | * Note that DISASSOCIATED should be flipped only while holding |
68 | * attach_mutex to avoid changing binding state while |
69 | * worker_attach_to_pool() is in progress. |
70 | */ |
71 | POOL_DISASSOCIATED = 1 << 2, /* cpu can't serve workers */ |
72 | |
73 | /* worker flags */ |
74 | WORKER_DIE = 1 << 1, /* die die die */ |
75 | WORKER_IDLE = 1 << 2, /* is idle */ |
76 | WORKER_PREP = 1 << 3, /* preparing to run works */ |
77 | WORKER_CPU_INTENSIVE = 1 << 6, /* cpu intensive */ |
78 | WORKER_UNBOUND = 1 << 7, /* worker is unbound */ |
79 | WORKER_REBOUND = 1 << 8, /* worker was rebound */ |
80 | |
81 | WORKER_NOT_RUNNING = WORKER_PREP | WORKER_CPU_INTENSIVE | |
82 | WORKER_UNBOUND | WORKER_REBOUND, |
83 | |
84 | NR_STD_WORKER_POOLS = 2, /* # standard pools per cpu */ |
85 | |
86 | UNBOUND_POOL_HASH_ORDER = 6, /* hashed by pool->attrs */ |
87 | BUSY_WORKER_HASH_ORDER = 6, /* 64 pointers */ |
88 | |
89 | MAX_IDLE_WORKERS_RATIO = 4, /* 1/4 of busy can be idle */ |
90 | IDLE_WORKER_TIMEOUT = 300 * HZ, /* keep idle ones for 5 mins */ |
91 | |
92 | MAYDAY_INITIAL_TIMEOUT = HZ / 100 >= 2 ? HZ / 100 : 2, |
93 | /* call for help after 10ms |
94 | (min two ticks) */ |
95 | MAYDAY_INTERVAL = HZ / 10, /* and then every 100ms */ |
96 | CREATE_COOLDOWN = HZ, /* time to breath after fail */ |
97 | |
98 | /* |
99 | * Rescue workers are used only on emergencies and shared by |
100 | * all cpus. Give MIN_NICE. |
101 | */ |
102 | RESCUER_NICE_LEVEL = MIN_NICE, |
103 | HIGHPRI_NICE_LEVEL = MIN_NICE, |
104 | |
105 | WQ_NAME_LEN = 24, |
106 | }; |
107 | |
108 | /* |
109 | * Structure fields follow one of the following exclusion rules. |
110 | * |
111 | * I: Modifiable by initialization/destruction paths and read-only for |
112 | * everyone else. |
113 | * |
114 | * P: Preemption protected. Disabling preemption is enough and should |
115 | * only be modified and accessed from the local cpu. |
116 | * |
117 | * L: pool->lock protected. Access with pool->lock held. |
118 | * |
119 | * X: During normal operation, modification requires pool->lock and should |
120 | * be done only from local cpu. Either disabling preemption on local |
121 | * cpu or grabbing pool->lock is enough for read access. If |
122 | * POOL_DISASSOCIATED is set, it's identical to L. |
123 | * |
124 | * A: pool->attach_mutex protected. |
125 | * |
126 | * PL: wq_pool_mutex protected. |
127 | * |
128 | * PR: wq_pool_mutex protected for writes. Sched-RCU protected for reads. |
129 | * |
130 | * WQ: wq->mutex protected. |
131 | * |
132 | * WR: wq->mutex protected for writes. Sched-RCU protected for reads. |
133 | * |
134 | * MD: wq_mayday_lock protected. |
135 | */ |
136 | |
137 | /* struct worker is defined in workqueue_internal.h */ |
138 | |
139 | struct worker_pool { |
140 | spinlock_t lock; /* the pool lock */ |
141 | int cpu; /* I: the associated cpu */ |
142 | int node; /* I: the associated node ID */ |
143 | int id; /* I: pool ID */ |
144 | unsigned int flags; /* X: flags */ |
145 | |
146 | struct list_head worklist; /* L: list of pending works */ |
147 | int nr_workers; /* L: total number of workers */ |
148 | |
149 | /* nr_idle includes the ones off idle_list for rebinding */ |
150 | int nr_idle; /* L: currently idle ones */ |
151 | |
152 | struct list_head idle_list; /* X: list of idle workers */ |
153 | struct timer_list idle_timer; /* L: worker idle timeout */ |
154 | struct timer_list mayday_timer; /* L: SOS timer for workers */ |
155 | |
156 | /* a workers is either on busy_hash or idle_list, or the manager */ |
157 | DECLARE_HASHTABLE(busy_hash, BUSY_WORKER_HASH_ORDER); |
158 | /* L: hash of busy workers */ |
159 | |
160 | /* see manage_workers() for details on the two manager mutexes */ |
161 | struct mutex manager_arb; /* manager arbitration */ |
162 | struct mutex attach_mutex; /* attach/detach exclusion */ |
163 | struct list_head workers; /* A: attached workers */ |
164 | struct completion *detach_completion; /* all workers detached */ |
165 | |
166 | struct ida worker_ida; /* worker IDs for task name */ |
167 | |
168 | struct workqueue_attrs *attrs; /* I: worker attributes */ |
169 | struct hlist_node hash_node; /* PL: unbound_pool_hash node */ |
170 | int refcnt; /* PL: refcnt for unbound pools */ |
171 | |
172 | /* |
173 | * The current concurrency level. As it's likely to be accessed |
174 | * from other CPUs during try_to_wake_up(), put it in a separate |
175 | * cacheline. |
176 | */ |
177 | atomic_t nr_running ____cacheline_aligned_in_smp; |
178 | |
179 | /* |
180 | * Destruction of pool is sched-RCU protected to allow dereferences |
181 | * from get_work_pool(). |
182 | */ |
183 | struct rcu_head rcu; |
184 | } ____cacheline_aligned_in_smp; |
185 | |
186 | /* |
187 | * The per-pool workqueue. While queued, the lower WORK_STRUCT_FLAG_BITS |
188 | * of work_struct->data are used for flags and the remaining high bits |
189 | * point to the pwq; thus, pwqs need to be aligned at two's power of the |
190 | * number of flag bits. |
191 | */ |
192 | struct pool_workqueue { |
193 | struct worker_pool *pool; /* I: the associated pool */ |
194 | struct workqueue_struct *wq; /* I: the owning workqueue */ |
195 | int work_color; /* L: current color */ |
196 | int flush_color; /* L: flushing color */ |
197 | int refcnt; /* L: reference count */ |
198 | int nr_in_flight[WORK_NR_COLORS]; |
199 | /* L: nr of in_flight works */ |
200 | int nr_active; /* L: nr of active works */ |
201 | int max_active; /* L: max active works */ |
202 | struct list_head delayed_works; /* L: delayed works */ |
203 | struct list_head pwqs_node; /* WR: node on wq->pwqs */ |
204 | struct list_head mayday_node; /* MD: node on wq->maydays */ |
205 | |
206 | /* |
207 | * Release of unbound pwq is punted to system_wq. See put_pwq() |
208 | * and pwq_unbound_release_workfn() for details. pool_workqueue |
209 | * itself is also sched-RCU protected so that the first pwq can be |
210 | * determined without grabbing wq->mutex. |
211 | */ |
212 | struct work_struct unbound_release_work; |
213 | struct rcu_head rcu; |
214 | } __aligned(1 << WORK_STRUCT_FLAG_BITS); |
215 | |
216 | /* |
217 | * Structure used to wait for workqueue flush. |
218 | */ |
219 | struct wq_flusher { |
220 | struct list_head list; /* WQ: list of flushers */ |
221 | int flush_color; /* WQ: flush color waiting for */ |
222 | struct completion done; /* flush completion */ |
223 | }; |
224 | |
225 | struct wq_device; |
226 | |
227 | /* |
228 | * The externally visible workqueue. It relays the issued work items to |
229 | * the appropriate worker_pool through its pool_workqueues. |
230 | */ |
231 | struct workqueue_struct { |
232 | struct list_head pwqs; /* WR: all pwqs of this wq */ |
233 | struct list_head list; /* PL: list of all workqueues */ |
234 | |
235 | struct mutex mutex; /* protects this wq */ |
236 | int work_color; /* WQ: current work color */ |
237 | int flush_color; /* WQ: current flush color */ |
238 | atomic_t nr_pwqs_to_flush; /* flush in progress */ |
239 | struct wq_flusher *first_flusher; /* WQ: first flusher */ |
240 | struct list_head flusher_queue; /* WQ: flush waiters */ |
241 | struct list_head flusher_overflow; /* WQ: flush overflow list */ |
242 | |
243 | struct list_head maydays; /* MD: pwqs requesting rescue */ |
244 | struct worker *rescuer; /* I: rescue worker */ |
245 | |
246 | int nr_drainers; /* WQ: drain in progress */ |
247 | int saved_max_active; /* WQ: saved pwq max_active */ |
248 | |
249 | struct workqueue_attrs *unbound_attrs; /* WQ: only for unbound wqs */ |
250 | struct pool_workqueue *dfl_pwq; /* WQ: only for unbound wqs */ |
251 | |
252 | #ifdef CONFIG_SYSFS |
253 | struct wq_device *wq_dev; /* I: for sysfs interface */ |
254 | #endif |
255 | #ifdef CONFIG_LOCKDEP |
256 | struct lockdep_map lockdep_map; |
257 | #endif |
258 | char name[WQ_NAME_LEN]; /* I: workqueue name */ |
259 | |
260 | /* hot fields used during command issue, aligned to cacheline */ |
261 | unsigned int flags ____cacheline_aligned; /* WQ: WQ_* flags */ |
262 | struct pool_workqueue __percpu *cpu_pwqs; /* I: per-cpu pwqs */ |
263 | struct pool_workqueue __rcu *numa_pwq_tbl[]; /* FR: unbound pwqs indexed by node */ |
264 | }; |
265 | |
266 | static struct kmem_cache *pwq_cache; |
267 | |
268 | static int wq_numa_tbl_len; /* highest possible NUMA node id + 1 */ |
269 | static cpumask_var_t *wq_numa_possible_cpumask; |
270 | /* possible CPUs of each node */ |
271 | |
272 | static bool wq_disable_numa; |
273 | module_param_named(disable_numa, wq_disable_numa, bool, 0444); |
274 | |
275 | /* see the comment above the definition of WQ_POWER_EFFICIENT */ |
276 | #ifdef CONFIG_WQ_POWER_EFFICIENT_DEFAULT |
277 | static bool wq_power_efficient = true; |
278 | #else |
279 | static bool wq_power_efficient; |
280 | #endif |
281 | |
282 | module_param_named(power_efficient, wq_power_efficient, bool, 0444); |
283 | |
284 | static bool wq_numa_enabled; /* unbound NUMA affinity enabled */ |
285 | |
286 | /* buf for wq_update_unbound_numa_attrs(), protected by CPU hotplug exclusion */ |
287 | static struct workqueue_attrs *wq_update_unbound_numa_attrs_buf; |
288 | |
289 | static DEFINE_MUTEX(wq_pool_mutex); /* protects pools and workqueues list */ |
290 | static DEFINE_SPINLOCK(wq_mayday_lock); /* protects wq->maydays list */ |
291 | |
292 | static LIST_HEAD(workqueues); /* PL: list of all workqueues */ |
293 | static bool workqueue_freezing; /* PL: have wqs started freezing? */ |
294 | |
295 | /* the per-cpu worker pools */ |
296 | static DEFINE_PER_CPU_SHARED_ALIGNED(struct worker_pool [NR_STD_WORKER_POOLS], |
297 | cpu_worker_pools); |
298 | |
299 | static DEFINE_IDR(worker_pool_idr); /* PR: idr of all pools */ |
300 | |
301 | /* PL: hash of all unbound pools keyed by pool->attrs */ |
302 | static DEFINE_HASHTABLE(unbound_pool_hash, UNBOUND_POOL_HASH_ORDER); |
303 | |
304 | /* I: attributes used when instantiating standard unbound pools on demand */ |
305 | static struct workqueue_attrs *unbound_std_wq_attrs[NR_STD_WORKER_POOLS]; |
306 | |
307 | /* I: attributes used when instantiating ordered pools on demand */ |
308 | static struct workqueue_attrs *ordered_wq_attrs[NR_STD_WORKER_POOLS]; |
309 | |
310 | struct workqueue_struct *system_wq __read_mostly; |
311 | EXPORT_SYMBOL(system_wq); |
312 | struct workqueue_struct *system_highpri_wq __read_mostly; |
313 | EXPORT_SYMBOL_GPL(system_highpri_wq); |
314 | struct workqueue_struct *system_long_wq __read_mostly; |
315 | EXPORT_SYMBOL_GPL(system_long_wq); |
316 | struct workqueue_struct *system_unbound_wq __read_mostly; |
317 | EXPORT_SYMBOL_GPL(system_unbound_wq); |
318 | struct workqueue_struct *system_freezable_wq __read_mostly; |
319 | EXPORT_SYMBOL_GPL(system_freezable_wq); |
320 | struct workqueue_struct *system_power_efficient_wq __read_mostly; |
321 | EXPORT_SYMBOL_GPL(system_power_efficient_wq); |
322 | struct workqueue_struct *system_freezable_power_efficient_wq __read_mostly; |
323 | EXPORT_SYMBOL_GPL(system_freezable_power_efficient_wq); |
324 | |
325 | static int worker_thread(void *__worker); |
326 | static void copy_workqueue_attrs(struct workqueue_attrs *to, |
327 | const struct workqueue_attrs *from); |
328 | |
329 | #define CREATE_TRACE_POINTS |
330 | #include <trace/events/workqueue.h> |
331 | |
332 | #define assert_rcu_or_pool_mutex() \ |
333 | rcu_lockdep_assert(rcu_read_lock_sched_held() || \ |
334 | lockdep_is_held(&wq_pool_mutex), \ |
335 | "sched RCU or wq_pool_mutex should be held") |
336 | |
337 | #define assert_rcu_or_wq_mutex(wq) \ |
338 | rcu_lockdep_assert(rcu_read_lock_sched_held() || \ |
339 | lockdep_is_held(&wq->mutex), \ |
340 | "sched RCU or wq->mutex should be held") |
341 | |
342 | #define for_each_cpu_worker_pool(pool, cpu) \ |
343 | for ((pool) = &per_cpu(cpu_worker_pools, cpu)[0]; \ |
344 | (pool) < &per_cpu(cpu_worker_pools, cpu)[NR_STD_WORKER_POOLS]; \ |
345 | (pool)++) |
346 | |
347 | /** |
348 | * for_each_pool - iterate through all worker_pools in the system |
349 | * @pool: iteration cursor |
350 | * @pi: integer used for iteration |
351 | * |
352 | * This must be called either with wq_pool_mutex held or sched RCU read |
353 | * locked. If the pool needs to be used beyond the locking in effect, the |
354 | * caller is responsible for guaranteeing that the pool stays online. |
355 | * |
356 | * The if/else clause exists only for the lockdep assertion and can be |
357 | * ignored. |
358 | */ |
359 | #define for_each_pool(pool, pi) \ |
360 | idr_for_each_entry(&worker_pool_idr, pool, pi) \ |
361 | if (({ assert_rcu_or_pool_mutex(); false; })) { } \ |
362 | else |
363 | |
364 | /** |
365 | * for_each_pool_worker - iterate through all workers of a worker_pool |
366 | * @worker: iteration cursor |
367 | * @pool: worker_pool to iterate workers of |
368 | * |
369 | * This must be called with @pool->attach_mutex. |
370 | * |
371 | * The if/else clause exists only for the lockdep assertion and can be |
372 | * ignored. |
373 | */ |
374 | #define for_each_pool_worker(worker, pool) \ |
375 | list_for_each_entry((worker), &(pool)->workers, node) \ |
376 | if (({ lockdep_assert_held(&pool->attach_mutex); false; })) { } \ |
377 | else |
378 | |
379 | /** |
380 | * for_each_pwq - iterate through all pool_workqueues of the specified workqueue |
381 | * @pwq: iteration cursor |
382 | * @wq: the target workqueue |
383 | * |
384 | * This must be called either with wq->mutex held or sched RCU read locked. |
385 | * If the pwq needs to be used beyond the locking in effect, the caller is |
386 | * responsible for guaranteeing that the pwq stays online. |
387 | * |
388 | * The if/else clause exists only for the lockdep assertion and can be |
389 | * ignored. |
390 | */ |
391 | #define for_each_pwq(pwq, wq) \ |
392 | list_for_each_entry_rcu((pwq), &(wq)->pwqs, pwqs_node) \ |
393 | if (({ assert_rcu_or_wq_mutex(wq); false; })) { } \ |
394 | else |
395 | |
396 | #ifdef CONFIG_DEBUG_OBJECTS_WORK |
397 | |
398 | static struct debug_obj_descr work_debug_descr; |
399 | |
400 | static void *work_debug_hint(void *addr) |
401 | { |
402 | return ((struct work_struct *) addr)->func; |
403 | } |
404 | |
405 | /* |
406 | * fixup_init is called when: |
407 | * - an active object is initialized |
408 | */ |
409 | static int work_fixup_init(void *addr, enum debug_obj_state state) |
410 | { |
411 | struct work_struct *work = addr; |
412 | |
413 | switch (state) { |
414 | case ODEBUG_STATE_ACTIVE: |
415 | cancel_work_sync(work); |
416 | debug_object_init(work, &work_debug_descr); |
417 | return 1; |
418 | default: |
419 | return 0; |
420 | } |
421 | } |
422 | |
423 | /* |
424 | * fixup_activate is called when: |
425 | * - an active object is activated |
426 | * - an unknown object is activated (might be a statically initialized object) |
427 | */ |
428 | static int work_fixup_activate(void *addr, enum debug_obj_state state) |
429 | { |
430 | struct work_struct *work = addr; |
431 | |
432 | switch (state) { |
433 | |
434 | case ODEBUG_STATE_NOTAVAILABLE: |
435 | /* |
436 | * This is not really a fixup. The work struct was |
437 | * statically initialized. We just make sure that it |
438 | * is tracked in the object tracker. |
439 | */ |
440 | if (test_bit(WORK_STRUCT_STATIC_BIT, work_data_bits(work))) { |
441 | debug_object_init(work, &work_debug_descr); |
442 | debug_object_activate(work, &work_debug_descr); |
443 | return 0; |
444 | } |
445 | WARN_ON_ONCE(1); |
446 | return 0; |
447 | |
448 | case ODEBUG_STATE_ACTIVE: |
449 | WARN_ON(1); |
450 | |
451 | default: |
452 | return 0; |
453 | } |
454 | } |
455 | |
456 | /* |
457 | * fixup_free is called when: |
458 | * - an active object is freed |
459 | */ |
460 | static int work_fixup_free(void *addr, enum debug_obj_state state) |
461 | { |
462 | struct work_struct *work = addr; |
463 | |
464 | switch (state) { |
465 | case ODEBUG_STATE_ACTIVE: |
466 | cancel_work_sync(work); |
467 | debug_object_free(work, &work_debug_descr); |
468 | return 1; |
469 | default: |
470 | return 0; |
471 | } |
472 | } |
473 | |
474 | static struct debug_obj_descr work_debug_descr = { |
475 | .name = "work_struct", |
476 | .debug_hint = work_debug_hint, |
477 | .fixup_init = work_fixup_init, |
478 | .fixup_activate = work_fixup_activate, |
479 | .fixup_free = work_fixup_free, |
480 | }; |
481 | |
482 | static inline void debug_work_activate(struct work_struct *work) |
483 | { |
484 | debug_object_activate(work, &work_debug_descr); |
485 | } |
486 | |
487 | static inline void debug_work_deactivate(struct work_struct *work) |
488 | { |
489 | debug_object_deactivate(work, &work_debug_descr); |
490 | } |
491 | |
492 | void __init_work(struct work_struct *work, int onstack) |
493 | { |
494 | if (onstack) |
495 | debug_object_init_on_stack(work, &work_debug_descr); |
496 | else |
497 | debug_object_init(work, &work_debug_descr); |
498 | } |
499 | EXPORT_SYMBOL_GPL(__init_work); |
500 | |
501 | void destroy_work_on_stack(struct work_struct *work) |
502 | { |
503 | debug_object_free(work, &work_debug_descr); |
504 | } |
505 | EXPORT_SYMBOL_GPL(destroy_work_on_stack); |
506 | |
507 | void destroy_delayed_work_on_stack(struct delayed_work *work) |
508 | { |
509 | destroy_timer_on_stack(&work->timer); |
510 | debug_object_free(&work->work, &work_debug_descr); |
511 | } |
512 | EXPORT_SYMBOL_GPL(destroy_delayed_work_on_stack); |
513 | |
514 | #else |
515 | static inline void debug_work_activate(struct work_struct *work) { } |
516 | static inline void debug_work_deactivate(struct work_struct *work) { } |
517 | #endif |
518 | |
519 | /** |
520 | * worker_pool_assign_id - allocate ID and assing it to @pool |
521 | * @pool: the pool pointer of interest |
522 | * |
523 | * Returns 0 if ID in [0, WORK_OFFQ_POOL_NONE) is allocated and assigned |
524 | * successfully, -errno on failure. |
525 | */ |
526 | static int worker_pool_assign_id(struct worker_pool *pool) |
527 | { |
528 | int ret; |
529 | |
530 | lockdep_assert_held(&wq_pool_mutex); |
531 | |
532 | ret = idr_alloc(&worker_pool_idr, pool, 0, WORK_OFFQ_POOL_NONE, |
533 | GFP_KERNEL); |
534 | if (ret >= 0) { |
535 | pool->id = ret; |
536 | return 0; |
537 | } |
538 | return ret; |
539 | } |
540 | |
541 | /** |
542 | * unbound_pwq_by_node - return the unbound pool_workqueue for the given node |
543 | * @wq: the target workqueue |
544 | * @node: the node ID |
545 | * |
546 | * This must be called either with pwq_lock held or sched RCU read locked. |
547 | * If the pwq needs to be used beyond the locking in effect, the caller is |
548 | * responsible for guaranteeing that the pwq stays online. |
549 | * |
550 | * Return: The unbound pool_workqueue for @node. |
551 | */ |
552 | static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, |
553 | int node) |
554 | { |
555 | assert_rcu_or_wq_mutex(wq); |
556 | return rcu_dereference_raw(wq->numa_pwq_tbl[node]); |
557 | } |
558 | |
559 | static unsigned int work_color_to_flags(int color) |
560 | { |
561 | return color << WORK_STRUCT_COLOR_SHIFT; |
562 | } |
563 | |
564 | static int get_work_color(struct work_struct *work) |
565 | { |
566 | return (*work_data_bits(work) >> WORK_STRUCT_COLOR_SHIFT) & |
567 | ((1 << WORK_STRUCT_COLOR_BITS) - 1); |
568 | } |
569 | |
570 | static int work_next_color(int color) |
571 | { |
572 | return (color + 1) % WORK_NR_COLORS; |
573 | } |
574 | |
575 | /* |
576 | * While queued, %WORK_STRUCT_PWQ is set and non flag bits of a work's data |
577 | * contain the pointer to the queued pwq. Once execution starts, the flag |
578 | * is cleared and the high bits contain OFFQ flags and pool ID. |
579 | * |
580 | * set_work_pwq(), set_work_pool_and_clear_pending(), mark_work_canceling() |
581 | * and clear_work_data() can be used to set the pwq, pool or clear |
582 | * work->data. These functions should only be called while the work is |
583 | * owned - ie. while the PENDING bit is set. |
584 | * |
585 | * get_work_pool() and get_work_pwq() can be used to obtain the pool or pwq |
586 | * corresponding to a work. Pool is available once the work has been |
587 | * queued anywhere after initialization until it is sync canceled. pwq is |
588 | * available only while the work item is queued. |
589 | * |
590 | * %WORK_OFFQ_CANCELING is used to mark a work item which is being |
591 | * canceled. While being canceled, a work item may have its PENDING set |
592 | * but stay off timer and worklist for arbitrarily long and nobody should |
593 | * try to steal the PENDING bit. |
594 | */ |
595 | static inline void set_work_data(struct work_struct *work, unsigned long data, |
596 | unsigned long flags) |
597 | { |
598 | WARN_ON_ONCE(!work_pending(work)); |
599 | atomic_long_set(&work->data, data | flags | work_static(work)); |
600 | } |
601 | |
602 | static void set_work_pwq(struct work_struct *work, struct pool_workqueue *pwq, |
603 | unsigned long extra_flags) |
604 | { |
605 | set_work_data(work, (unsigned long)pwq, |
606 | WORK_STRUCT_PENDING | WORK_STRUCT_PWQ | extra_flags); |
607 | } |
608 | |
609 | static void set_work_pool_and_keep_pending(struct work_struct *work, |
610 | int pool_id) |
611 | { |
612 | set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, |
613 | WORK_STRUCT_PENDING); |
614 | } |
615 | |
616 | static void set_work_pool_and_clear_pending(struct work_struct *work, |
617 | int pool_id) |
618 | { |
619 | /* |
620 | * The following wmb is paired with the implied mb in |
621 | * test_and_set_bit(PENDING) and ensures all updates to @work made |
622 | * here are visible to and precede any updates by the next PENDING |
623 | * owner. |
624 | */ |
625 | smp_wmb(); |
626 | set_work_data(work, (unsigned long)pool_id << WORK_OFFQ_POOL_SHIFT, 0); |
627 | } |
628 | |
629 | static void clear_work_data(struct work_struct *work) |
630 | { |
631 | smp_wmb(); /* see set_work_pool_and_clear_pending() */ |
632 | set_work_data(work, WORK_STRUCT_NO_POOL, 0); |
633 | } |
634 | |
635 | static struct pool_workqueue *get_work_pwq(struct work_struct *work) |
636 | { |
637 | unsigned long data = atomic_long_read(&work->data); |
638 | |
639 | if (data & WORK_STRUCT_PWQ) |
640 | return (void *)(data & WORK_STRUCT_WQ_DATA_MASK); |
641 | else |
642 | return NULL; |
643 | } |
644 | |
645 | /** |
646 | * get_work_pool - return the worker_pool a given work was associated with |
647 | * @work: the work item of interest |
648 | * |
649 | * Pools are created and destroyed under wq_pool_mutex, and allows read |
650 | * access under sched-RCU read lock. As such, this function should be |
651 | * called under wq_pool_mutex or with preemption disabled. |
652 | * |
653 | * All fields of the returned pool are accessible as long as the above |
654 | * mentioned locking is in effect. If the returned pool needs to be used |
655 | * beyond the critical section, the caller is responsible for ensuring the |
656 | * returned pool is and stays online. |
657 | * |
658 | * Return: The worker_pool @work was last associated with. %NULL if none. |
659 | */ |
660 | static struct worker_pool *get_work_pool(struct work_struct *work) |
661 | { |
662 | unsigned long data = atomic_long_read(&work->data); |
663 | int pool_id; |
664 | |
665 | assert_rcu_or_pool_mutex(); |
666 | |
667 | if (data & WORK_STRUCT_PWQ) |
668 | return ((struct pool_workqueue *) |
669 | (data & WORK_STRUCT_WQ_DATA_MASK))->pool; |
670 | |
671 | pool_id = data >> WORK_OFFQ_POOL_SHIFT; |
672 | if (pool_id == WORK_OFFQ_POOL_NONE) |
673 | return NULL; |
674 | |
675 | return idr_find(&worker_pool_idr, pool_id); |
676 | } |
677 | |
678 | /** |
679 | * get_work_pool_id - return the worker pool ID a given work is associated with |
680 | * @work: the work item of interest |
681 | * |
682 | * Return: The worker_pool ID @work was last associated with. |
683 | * %WORK_OFFQ_POOL_NONE if none. |
684 | */ |
685 | static int get_work_pool_id(struct work_struct *work) |
686 | { |
687 | unsigned long data = atomic_long_read(&work->data); |
688 | |
689 | if (data & WORK_STRUCT_PWQ) |
690 | return ((struct pool_workqueue *) |
691 | (data & WORK_STRUCT_WQ_DATA_MASK))->pool->id; |
692 | |
693 | return data >> WORK_OFFQ_POOL_SHIFT; |
694 | } |
695 | |
696 | static void mark_work_canceling(struct work_struct *work) |
697 | { |
698 | unsigned long pool_id = get_work_pool_id(work); |
699 | |
700 | pool_id <<= WORK_OFFQ_POOL_SHIFT; |
701 | set_work_data(work, pool_id | WORK_OFFQ_CANCELING, WORK_STRUCT_PENDING); |
702 | } |
703 | |
704 | static bool work_is_canceling(struct work_struct *work) |
705 | { |
706 | unsigned long data = atomic_long_read(&work->data); |
707 | |
708 | return !(data & WORK_STRUCT_PWQ) && (data & WORK_OFFQ_CANCELING); |
709 | } |
710 | |
711 | /* |
712 | * Policy functions. These define the policies on how the global worker |
713 | * pools are managed. Unless noted otherwise, these functions assume that |
714 | * they're being called with pool->lock held. |
715 | */ |
716 | |
717 | static bool __need_more_worker(struct worker_pool *pool) |
718 | { |
719 | return !atomic_read(&pool->nr_running); |
720 | } |
721 | |
722 | /* |
723 | * Need to wake up a worker? Called from anything but currently |
724 | * running workers. |
725 | * |
726 | * Note that, because unbound workers never contribute to nr_running, this |
727 | * function will always return %true for unbound pools as long as the |
728 | * worklist isn't empty. |
729 | */ |
730 | static bool need_more_worker(struct worker_pool *pool) |
731 | { |
732 | return !list_empty(&pool->worklist) && __need_more_worker(pool); |
733 | } |
734 | |
735 | /* Can I start working? Called from busy but !running workers. */ |
736 | static bool may_start_working(struct worker_pool *pool) |
737 | { |
738 | return pool->nr_idle; |
739 | } |
740 | |
741 | /* Do I need to keep working? Called from currently running workers. */ |
742 | static bool keep_working(struct worker_pool *pool) |
743 | { |
744 | return !list_empty(&pool->worklist) && |
745 | atomic_read(&pool->nr_running) <= 1; |
746 | } |
747 | |
748 | /* Do we need a new worker? Called from manager. */ |
749 | static bool need_to_create_worker(struct worker_pool *pool) |
750 | { |
751 | return need_more_worker(pool) && !may_start_working(pool); |
752 | } |
753 | |
754 | /* Do we have too many workers and should some go away? */ |
755 | static bool too_many_workers(struct worker_pool *pool) |
756 | { |
757 | bool managing = mutex_is_locked(&pool->manager_arb); |
758 | int nr_idle = pool->nr_idle + managing; /* manager is considered idle */ |
759 | int nr_busy = pool->nr_workers - nr_idle; |
760 | |
761 | /* |
762 | * nr_idle and idle_list may disagree if idle rebinding is in |
763 | * progress. Never return %true if idle_list is empty. |
764 | */ |
765 | if (list_empty(&pool->idle_list)) |
766 | return false; |
767 | |
768 | return nr_idle > 2 && (nr_idle - 2) * MAX_IDLE_WORKERS_RATIO >= nr_busy; |
769 | } |
770 | |
771 | /* |
772 | * Wake up functions. |
773 | */ |
774 | |
775 | /* Return the first idle worker. Safe with preemption disabled */ |
776 | static struct worker *first_idle_worker(struct worker_pool *pool) |
777 | { |
778 | if (unlikely(list_empty(&pool->idle_list))) |
779 | return NULL; |
780 | |
781 | return list_first_entry(&pool->idle_list, struct worker, entry); |
782 | } |
783 | |
784 | /** |
785 | * wake_up_worker - wake up an idle worker |
786 | * @pool: worker pool to wake worker from |
787 | * |
788 | * Wake up the first idle worker of @pool. |
789 | * |
790 | * CONTEXT: |
791 | * spin_lock_irq(pool->lock). |
792 | */ |
793 | static void wake_up_worker(struct worker_pool *pool) |
794 | { |
795 | struct worker *worker = first_idle_worker(pool); |
796 | |
797 | if (likely(worker)) |
798 | wake_up_process(worker->task); |
799 | } |
800 | |
801 | /** |
802 | * wq_worker_waking_up - a worker is waking up |
803 | * @task: task waking up |
804 | * @cpu: CPU @task is waking up to |
805 | * |
806 | * This function is called during try_to_wake_up() when a worker is |
807 | * being awoken. |
808 | * |
809 | * CONTEXT: |
810 | * spin_lock_irq(rq->lock) |
811 | */ |
812 | void wq_worker_waking_up(struct task_struct *task, int cpu) |
813 | { |
814 | struct worker *worker = kthread_data(task); |
815 | |
816 | if (!(worker->flags & WORKER_NOT_RUNNING)) { |
817 | WARN_ON_ONCE(worker->pool->cpu != cpu); |
818 | atomic_inc(&worker->pool->nr_running); |
819 | } |
820 | } |
821 | |
822 | /** |
823 | * wq_worker_sleeping - a worker is going to sleep |
824 | * @task: task going to sleep |
825 | * @cpu: CPU in question, must be the current CPU number |
826 | * |
827 | * This function is called during schedule() when a busy worker is |
828 | * going to sleep. Worker on the same cpu can be woken up by |
829 | * returning pointer to its task. |
830 | * |
831 | * CONTEXT: |
832 | * spin_lock_irq(rq->lock) |
833 | * |
834 | * Return: |
835 | * Worker task on @cpu to wake up, %NULL if none. |
836 | */ |
837 | struct task_struct *wq_worker_sleeping(struct task_struct *task, int cpu) |
838 | { |
839 | struct worker *worker = kthread_data(task), *to_wakeup = NULL; |
840 | struct worker_pool *pool; |
841 | |
842 | /* |
843 | * Rescuers, which may not have all the fields set up like normal |
844 | * workers, also reach here, let's not access anything before |
845 | * checking NOT_RUNNING. |
846 | */ |
847 | if (worker->flags & WORKER_NOT_RUNNING) |
848 | return NULL; |
849 | |
850 | pool = worker->pool; |
851 | |
852 | /* this can only happen on the local cpu */ |
853 | if (WARN_ON_ONCE(cpu != raw_smp_processor_id())) |
854 | return NULL; |
855 | |
856 | /* |
857 | * The counterpart of the following dec_and_test, implied mb, |
858 | * worklist not empty test sequence is in insert_work(). |
859 | * Please read comment there. |
860 | * |
861 | * NOT_RUNNING is clear. This means that we're bound to and |
862 | * running on the local cpu w/ rq lock held and preemption |
863 | * disabled, which in turn means that none else could be |
864 | * manipulating idle_list, so dereferencing idle_list without pool |
865 | * lock is safe. |
866 | */ |
867 | if (atomic_dec_and_test(&pool->nr_running) && |
868 | !list_empty(&pool->worklist)) |
869 | to_wakeup = first_idle_worker(pool); |
870 | return to_wakeup ? to_wakeup->task : NULL; |
871 | } |
872 | |
873 | /** |
874 | * worker_set_flags - set worker flags and adjust nr_running accordingly |
875 | * @worker: self |
876 | * @flags: flags to set |
877 | * @wakeup: wakeup an idle worker if necessary |
878 | * |
879 | * Set @flags in @worker->flags and adjust nr_running accordingly. If |
880 | * nr_running becomes zero and @wakeup is %true, an idle worker is |
881 | * woken up. |
882 | * |
883 | * CONTEXT: |
884 | * spin_lock_irq(pool->lock) |
885 | */ |
886 | static inline void worker_set_flags(struct worker *worker, unsigned int flags, |
887 | bool wakeup) |
888 | { |
889 | struct worker_pool *pool = worker->pool; |
890 | |
891 | WARN_ON_ONCE(worker->task != current); |
892 | |
893 | /* |
894 | * If transitioning into NOT_RUNNING, adjust nr_running and |
895 | * wake up an idle worker as necessary if requested by |
896 | * @wakeup. |
897 | */ |
898 | if ((flags & WORKER_NOT_RUNNING) && |
899 | !(worker->flags & WORKER_NOT_RUNNING)) { |
900 | if (wakeup) { |
901 | if (atomic_dec_and_test(&pool->nr_running) && |
902 | !list_empty(&pool->worklist)) |
903 | wake_up_worker(pool); |
904 | } else |
905 | atomic_dec(&pool->nr_running); |
906 | } |
907 | |
908 | worker->flags |= flags; |
909 | } |
910 | |
911 | /** |
912 | * worker_clr_flags - clear worker flags and adjust nr_running accordingly |
913 | * @worker: self |
914 | * @flags: flags to clear |
915 | * |
916 | * Clear @flags in @worker->flags and adjust nr_running accordingly. |
917 | * |
918 | * CONTEXT: |
919 | * spin_lock_irq(pool->lock) |
920 | */ |
921 | static inline void worker_clr_flags(struct worker *worker, unsigned int flags) |
922 | { |
923 | struct worker_pool *pool = worker->pool; |
924 | unsigned int oflags = worker->flags; |
925 | |
926 | WARN_ON_ONCE(worker->task != current); |
927 | |
928 | worker->flags &= ~flags; |
929 | |
930 | /* |
931 | * If transitioning out of NOT_RUNNING, increment nr_running. Note |
932 | * that the nested NOT_RUNNING is not a noop. NOT_RUNNING is mask |
933 | * of multiple flags, not a single flag. |
934 | */ |
935 | if ((flags & WORKER_NOT_RUNNING) && (oflags & WORKER_NOT_RUNNING)) |
936 | if (!(worker->flags & WORKER_NOT_RUNNING)) |
937 | atomic_inc(&pool->nr_running); |
938 | } |
939 | |
940 | /** |
941 | * find_worker_executing_work - find worker which is executing a work |
942 | * @pool: pool of interest |
943 | * @work: work to find worker for |
944 | * |
945 | * Find a worker which is executing @work on @pool by searching |
946 | * @pool->busy_hash which is keyed by the address of @work. For a worker |
947 | * to match, its current execution should match the address of @work and |
948 | * its work function. This is to avoid unwanted dependency between |
949 | * unrelated work executions through a work item being recycled while still |
950 | * being executed. |
951 | * |
952 | * This is a bit tricky. A work item may be freed once its execution |
953 | * starts and nothing prevents the freed area from being recycled for |
954 | * another work item. If the same work item address ends up being reused |
955 | * before the original execution finishes, workqueue will identify the |
956 | * recycled work item as currently executing and make it wait until the |
957 | * current execution finishes, introducing an unwanted dependency. |
958 | * |
959 | * This function checks the work item address and work function to avoid |
960 | * false positives. Note that this isn't complete as one may construct a |
961 | * work function which can introduce dependency onto itself through a |
962 | * recycled work item. Well, if somebody wants to shoot oneself in the |
963 | * foot that badly, there's only so much we can do, and if such deadlock |
964 | * actually occurs, it should be easy to locate the culprit work function. |
965 | * |
966 | * CONTEXT: |
967 | * spin_lock_irq(pool->lock). |
968 | * |
969 | * Return: |
970 | * Pointer to worker which is executing @work if found, %NULL |
971 | * otherwise. |
972 | */ |
973 | static struct worker *find_worker_executing_work(struct worker_pool *pool, |
974 | struct work_struct *work) |
975 | { |
976 | struct worker *worker; |
977 | |
978 | hash_for_each_possible(pool->busy_hash, worker, hentry, |
979 | (unsigned long)work) |
980 | if (worker->current_work == work && |
981 | worker->current_func == work->func) |
982 | return worker; |
983 | |
984 | return NULL; |
985 | } |
986 | |
987 | /** |
988 | * move_linked_works - move linked works to a list |
989 | * @work: start of series of works to be scheduled |
990 | * @head: target list to append @work to |
991 | * @nextp: out paramter for nested worklist walking |
992 | * |
993 | * Schedule linked works starting from @work to @head. Work series to |
994 | * be scheduled starts at @work and includes any consecutive work with |
995 | * WORK_STRUCT_LINKED set in its predecessor. |
996 | * |
997 | * If @nextp is not NULL, it's updated to point to the next work of |
998 | * the last scheduled work. This allows move_linked_works() to be |
999 | * nested inside outer list_for_each_entry_safe(). |
1000 | * |
1001 | * CONTEXT: |
1002 | * spin_lock_irq(pool->lock). |
1003 | */ |
1004 | static void move_linked_works(struct work_struct *work, struct list_head *head, |
1005 | struct work_struct **nextp) |
1006 | { |
1007 | struct work_struct *n; |
1008 | |
1009 | /* |
1010 | * Linked worklist will always end before the end of the list, |
1011 | * use NULL for list head. |
1012 | */ |
1013 | list_for_each_entry_safe_from(work, n, NULL, entry) { |
1014 | list_move_tail(&work->entry, head); |
1015 | if (!(*work_data_bits(work) & WORK_STRUCT_LINKED)) |
1016 | break; |
1017 | } |
1018 | |
1019 | /* |
1020 | * If we're already inside safe list traversal and have moved |
1021 | * multiple works to the scheduled queue, the next position |
1022 | * needs to be updated. |
1023 | */ |
1024 | if (nextp) |
1025 | *nextp = n; |
1026 | } |
1027 | |
1028 | /** |
1029 | * get_pwq - get an extra reference on the specified pool_workqueue |
1030 | * @pwq: pool_workqueue to get |
1031 | * |
1032 | * Obtain an extra reference on @pwq. The caller should guarantee that |
1033 | * @pwq has positive refcnt and be holding the matching pool->lock. |
1034 | */ |
1035 | static void get_pwq(struct pool_workqueue *pwq) |
1036 | { |
1037 | lockdep_assert_held(&pwq->pool->lock); |
1038 | WARN_ON_ONCE(pwq->refcnt <= 0); |
1039 | pwq->refcnt++; |
1040 | } |
1041 | |
1042 | /** |
1043 | * put_pwq - put a pool_workqueue reference |
1044 | * @pwq: pool_workqueue to put |
1045 | * |
1046 | * Drop a reference of @pwq. If its refcnt reaches zero, schedule its |
1047 | * destruction. The caller should be holding the matching pool->lock. |
1048 | */ |
1049 | static void put_pwq(struct pool_workqueue *pwq) |
1050 | { |
1051 | lockdep_assert_held(&pwq->pool->lock); |
1052 | if (likely(--pwq->refcnt)) |
1053 | return; |
1054 | if (WARN_ON_ONCE(!(pwq->wq->flags & WQ_UNBOUND))) |
1055 | return; |
1056 | /* |
1057 | * @pwq can't be released under pool->lock, bounce to |
1058 | * pwq_unbound_release_workfn(). This never recurses on the same |
1059 | * pool->lock as this path is taken only for unbound workqueues and |
1060 | * the release work item is scheduled on a per-cpu workqueue. To |
1061 | * avoid lockdep warning, unbound pool->locks are given lockdep |
1062 | * subclass of 1 in get_unbound_pool(). |
1063 | */ |
1064 | schedule_work(&pwq->unbound_release_work); |
1065 | } |
1066 | |
1067 | /** |
1068 | * put_pwq_unlocked - put_pwq() with surrounding pool lock/unlock |
1069 | * @pwq: pool_workqueue to put (can be %NULL) |
1070 | * |
1071 | * put_pwq() with locking. This function also allows %NULL @pwq. |
1072 | */ |
1073 | static void put_pwq_unlocked(struct pool_workqueue *pwq) |
1074 | { |
1075 | if (pwq) { |
1076 | /* |
1077 | * As both pwqs and pools are sched-RCU protected, the |
1078 | * following lock operations are safe. |
1079 | */ |
1080 | spin_lock_irq(&pwq->pool->lock); |
1081 | put_pwq(pwq); |
1082 | spin_unlock_irq(&pwq->pool->lock); |
1083 | } |
1084 | } |
1085 | |
1086 | static void pwq_activate_delayed_work(struct work_struct *work) |
1087 | { |
1088 | struct pool_workqueue *pwq = get_work_pwq(work); |
1089 | |
1090 | trace_workqueue_activate_work(work); |
1091 | move_linked_works(work, &pwq->pool->worklist, NULL); |
1092 | __clear_bit(WORK_STRUCT_DELAYED_BIT, work_data_bits(work)); |
1093 | pwq->nr_active++; |
1094 | } |
1095 | |
1096 | static void pwq_activate_first_delayed(struct pool_workqueue *pwq) |
1097 | { |
1098 | struct work_struct *work = list_first_entry(&pwq->delayed_works, |
1099 | struct work_struct, entry); |
1100 | |
1101 | pwq_activate_delayed_work(work); |
1102 | } |
1103 | |
1104 | /** |
1105 | * pwq_dec_nr_in_flight - decrement pwq's nr_in_flight |
1106 | * @pwq: pwq of interest |
1107 | * @color: color of work which left the queue |
1108 | * |
1109 | * A work either has completed or is removed from pending queue, |
1110 | * decrement nr_in_flight of its pwq and handle workqueue flushing. |
1111 | * |
1112 | * CONTEXT: |
1113 | * spin_lock_irq(pool->lock). |
1114 | */ |
1115 | static void pwq_dec_nr_in_flight(struct pool_workqueue *pwq, int color) |
1116 | { |
1117 | /* uncolored work items don't participate in flushing or nr_active */ |
1118 | if (color == WORK_NO_COLOR) |
1119 | goto out_put; |
1120 | |
1121 | pwq->nr_in_flight[color]--; |
1122 | |
1123 | pwq->nr_active--; |
1124 | if (!list_empty(&pwq->delayed_works)) { |
1125 | /* one down, submit a delayed one */ |
1126 | if (pwq->nr_active < pwq->max_active) |
1127 | pwq_activate_first_delayed(pwq); |
1128 | } |
1129 | |
1130 | /* is flush in progress and are we at the flushing tip? */ |
1131 | if (likely(pwq->flush_color != color)) |
1132 | goto out_put; |
1133 | |
1134 | /* are there still in-flight works? */ |
1135 | if (pwq->nr_in_flight[color]) |
1136 | goto out_put; |
1137 | |
1138 | /* this pwq is done, clear flush_color */ |
1139 | pwq->flush_color = -1; |
1140 | |
1141 | /* |
1142 | * If this was the last pwq, wake up the first flusher. It |
1143 | * will handle the rest. |
1144 | */ |
1145 | if (atomic_dec_and_test(&pwq->wq->nr_pwqs_to_flush)) |
1146 | complete(&pwq->wq->first_flusher->done); |
1147 | out_put: |
1148 | put_pwq(pwq); |
1149 | } |
1150 | |
1151 | /** |
1152 | * try_to_grab_pending - steal work item from worklist and disable irq |
1153 | * @work: work item to steal |
1154 | * @is_dwork: @work is a delayed_work |
1155 | * @flags: place to store irq state |
1156 | * |
1157 | * Try to grab PENDING bit of @work. This function can handle @work in any |
1158 | * stable state - idle, on timer or on worklist. |
1159 | * |
1160 | * Return: |
1161 | * 1 if @work was pending and we successfully stole PENDING |
1162 | * 0 if @work was idle and we claimed PENDING |
1163 | * -EAGAIN if PENDING couldn't be grabbed at the moment, safe to busy-retry |
1164 | * -ENOENT if someone else is canceling @work, this state may persist |
1165 | * for arbitrarily long |
1166 | * |
1167 | * Note: |
1168 | * On >= 0 return, the caller owns @work's PENDING bit. To avoid getting |
1169 | * interrupted while holding PENDING and @work off queue, irq must be |
1170 | * disabled on entry. This, combined with delayed_work->timer being |
1171 | * irqsafe, ensures that we return -EAGAIN for finite short period of time. |
1172 | * |
1173 | * On successful return, >= 0, irq is disabled and the caller is |
1174 | * responsible for releasing it using local_irq_restore(*@flags). |
1175 | * |
1176 | * This function is safe to call from any context including IRQ handler. |
1177 | */ |
1178 | static int try_to_grab_pending(struct work_struct *work, bool is_dwork, |
1179 | unsigned long *flags) |
1180 | { |
1181 | struct worker_pool *pool; |
1182 | struct pool_workqueue *pwq; |
1183 | |
1184 | local_irq_save(*flags); |
1185 | |
1186 | /* try to steal the timer if it exists */ |
1187 | if (is_dwork) { |
1188 | struct delayed_work *dwork = to_delayed_work(work); |
1189 | |
1190 | /* |
1191 | * dwork->timer is irqsafe. If del_timer() fails, it's |
1192 | * guaranteed that the timer is not queued anywhere and not |
1193 | * running on the local CPU. |
1194 | */ |
1195 | if (likely(del_timer(&dwork->timer))) |
1196 | return 1; |
1197 | } |
1198 | |
1199 | /* try to claim PENDING the normal way */ |
1200 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) |
1201 | return 0; |
1202 | |
1203 | /* |
1204 | * The queueing is in progress, or it is already queued. Try to |
1205 | * steal it from ->worklist without clearing WORK_STRUCT_PENDING. |
1206 | */ |
1207 | pool = get_work_pool(work); |
1208 | if (!pool) |
1209 | goto fail; |
1210 | |
1211 | spin_lock(&pool->lock); |
1212 | /* |
1213 | * work->data is guaranteed to point to pwq only while the work |
1214 | * item is queued on pwq->wq, and both updating work->data to point |
1215 | * to pwq on queueing and to pool on dequeueing are done under |
1216 | * pwq->pool->lock. This in turn guarantees that, if work->data |
1217 | * points to pwq which is associated with a locked pool, the work |
1218 | * item is currently queued on that pool. |
1219 | */ |
1220 | pwq = get_work_pwq(work); |
1221 | if (pwq && pwq->pool == pool) { |
1222 | debug_work_deactivate(work); |
1223 | |
1224 | /* |
1225 | * A delayed work item cannot be grabbed directly because |
1226 | * it might have linked NO_COLOR work items which, if left |
1227 | * on the delayed_list, will confuse pwq->nr_active |
1228 | * management later on and cause stall. Make sure the work |
1229 | * item is activated before grabbing. |
1230 | */ |
1231 | if (*work_data_bits(work) & WORK_STRUCT_DELAYED) |
1232 | pwq_activate_delayed_work(work); |
1233 | |
1234 | list_del_init(&work->entry); |
1235 | pwq_dec_nr_in_flight(get_work_pwq(work), get_work_color(work)); |
1236 | |
1237 | /* work->data points to pwq iff queued, point to pool */ |
1238 | set_work_pool_and_keep_pending(work, pool->id); |
1239 | |
1240 | spin_unlock(&pool->lock); |
1241 | return 1; |
1242 | } |
1243 | spin_unlock(&pool->lock); |
1244 | fail: |
1245 | local_irq_restore(*flags); |
1246 | if (work_is_canceling(work)) |
1247 | return -ENOENT; |
1248 | cpu_relax(); |
1249 | return -EAGAIN; |
1250 | } |
1251 | |
1252 | /** |
1253 | * insert_work - insert a work into a pool |
1254 | * @pwq: pwq @work belongs to |
1255 | * @work: work to insert |
1256 | * @head: insertion point |
1257 | * @extra_flags: extra WORK_STRUCT_* flags to set |
1258 | * |
1259 | * Insert @work which belongs to @pwq after @head. @extra_flags is or'd to |
1260 | * work_struct flags. |
1261 | * |
1262 | * CONTEXT: |
1263 | * spin_lock_irq(pool->lock). |
1264 | */ |
1265 | static void insert_work(struct pool_workqueue *pwq, struct work_struct *work, |
1266 | struct list_head *head, unsigned int extra_flags) |
1267 | { |
1268 | struct worker_pool *pool = pwq->pool; |
1269 | |
1270 | /* we own @work, set data and link */ |
1271 | set_work_pwq(work, pwq, extra_flags); |
1272 | list_add_tail(&work->entry, head); |
1273 | get_pwq(pwq); |
1274 | |
1275 | /* |
1276 | * Ensure either wq_worker_sleeping() sees the above |
1277 | * list_add_tail() or we see zero nr_running to avoid workers lying |
1278 | * around lazily while there are works to be processed. |
1279 | */ |
1280 | smp_mb(); |
1281 | |
1282 | if (__need_more_worker(pool)) |
1283 | wake_up_worker(pool); |
1284 | } |
1285 | |
1286 | /* |
1287 | * Test whether @work is being queued from another work executing on the |
1288 | * same workqueue. |
1289 | */ |
1290 | static bool is_chained_work(struct workqueue_struct *wq) |
1291 | { |
1292 | struct worker *worker; |
1293 | |
1294 | worker = current_wq_worker(); |
1295 | /* |
1296 | * Return %true iff I'm a worker execuing a work item on @wq. If |
1297 | * I'm @worker, it's safe to dereference it without locking. |
1298 | */ |
1299 | return worker && worker->current_pwq->wq == wq; |
1300 | } |
1301 | |
1302 | static void __queue_work(int cpu, struct workqueue_struct *wq, |
1303 | struct work_struct *work) |
1304 | { |
1305 | struct pool_workqueue *pwq; |
1306 | struct worker_pool *last_pool; |
1307 | struct list_head *worklist; |
1308 | unsigned int work_flags; |
1309 | unsigned int req_cpu = cpu; |
1310 | |
1311 | /* |
1312 | * While a work item is PENDING && off queue, a task trying to |
1313 | * steal the PENDING will busy-loop waiting for it to either get |
1314 | * queued or lose PENDING. Grabbing PENDING and queueing should |
1315 | * happen with IRQ disabled. |
1316 | */ |
1317 | WARN_ON_ONCE(!irqs_disabled()); |
1318 | |
1319 | debug_work_activate(work); |
1320 | |
1321 | /* if draining, only works from the same workqueue are allowed */ |
1322 | if (unlikely(wq->flags & __WQ_DRAINING) && |
1323 | WARN_ON_ONCE(!is_chained_work(wq))) |
1324 | return; |
1325 | retry: |
1326 | if (req_cpu == WORK_CPU_UNBOUND) |
1327 | cpu = raw_smp_processor_id(); |
1328 | |
1329 | /* pwq which will be used unless @work is executing elsewhere */ |
1330 | if (!(wq->flags & WQ_UNBOUND)) |
1331 | pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); |
1332 | else |
1333 | pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); |
1334 | |
1335 | /* |
1336 | * If @work was previously on a different pool, it might still be |
1337 | * running there, in which case the work needs to be queued on that |
1338 | * pool to guarantee non-reentrancy. |
1339 | */ |
1340 | last_pool = get_work_pool(work); |
1341 | if (last_pool && last_pool != pwq->pool) { |
1342 | struct worker *worker; |
1343 | |
1344 | spin_lock(&last_pool->lock); |
1345 | |
1346 | worker = find_worker_executing_work(last_pool, work); |
1347 | |
1348 | if (worker && worker->current_pwq->wq == wq) { |
1349 | pwq = worker->current_pwq; |
1350 | } else { |
1351 | /* meh... not running there, queue here */ |
1352 | spin_unlock(&last_pool->lock); |
1353 | spin_lock(&pwq->pool->lock); |
1354 | } |
1355 | } else { |
1356 | spin_lock(&pwq->pool->lock); |
1357 | } |
1358 | |
1359 | /* |
1360 | * pwq is determined and locked. For unbound pools, we could have |
1361 | * raced with pwq release and it could already be dead. If its |
1362 | * refcnt is zero, repeat pwq selection. Note that pwqs never die |
1363 | * without another pwq replacing it in the numa_pwq_tbl or while |
1364 | * work items are executing on it, so the retrying is guaranteed to |
1365 | * make forward-progress. |
1366 | */ |
1367 | if (unlikely(!pwq->refcnt)) { |
1368 | if (wq->flags & WQ_UNBOUND) { |
1369 | spin_unlock(&pwq->pool->lock); |
1370 | cpu_relax(); |
1371 | goto retry; |
1372 | } |
1373 | /* oops */ |
1374 | WARN_ONCE(true, "workqueue: per-cpu pwq for %s on cpu%d has 0 refcnt", |
1375 | wq->name, cpu); |
1376 | } |
1377 | |
1378 | /* pwq determined, queue */ |
1379 | trace_workqueue_queue_work(req_cpu, pwq, work); |
1380 | |
1381 | if (WARN_ON(!list_empty(&work->entry))) { |
1382 | spin_unlock(&pwq->pool->lock); |
1383 | return; |
1384 | } |
1385 | |
1386 | pwq->nr_in_flight[pwq->work_color]++; |
1387 | work_flags = work_color_to_flags(pwq->work_color); |
1388 | |
1389 | if (likely(pwq->nr_active < pwq->max_active)) { |
1390 | trace_workqueue_activate_work(work); |
1391 | pwq->nr_active++; |
1392 | worklist = &pwq->pool->worklist; |
1393 | } else { |
1394 | work_flags |= WORK_STRUCT_DELAYED; |
1395 | worklist = &pwq->delayed_works; |
1396 | } |
1397 | |
1398 | insert_work(pwq, work, worklist, work_flags); |
1399 | |
1400 | spin_unlock(&pwq->pool->lock); |
1401 | } |
1402 | |
1403 | /** |
1404 | * queue_work_on - queue work on specific cpu |
1405 | * @cpu: CPU number to execute work on |
1406 | * @wq: workqueue to use |
1407 | * @work: work to queue |
1408 | * |
1409 | * We queue the work to a specific CPU, the caller must ensure it |
1410 | * can't go away. |
1411 | * |
1412 | * Return: %false if @work was already on a queue, %true otherwise. |
1413 | */ |
1414 | bool queue_work_on(int cpu, struct workqueue_struct *wq, |
1415 | struct work_struct *work) |
1416 | { |
1417 | bool ret = false; |
1418 | unsigned long flags; |
1419 | |
1420 | local_irq_save(flags); |
1421 | |
1422 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1423 | __queue_work(cpu, wq, work); |
1424 | ret = true; |
1425 | } |
1426 | |
1427 | local_irq_restore(flags); |
1428 | return ret; |
1429 | } |
1430 | EXPORT_SYMBOL(queue_work_on); |
1431 | |
1432 | void delayed_work_timer_fn(unsigned long __data) |
1433 | { |
1434 | struct delayed_work *dwork = (struct delayed_work *)__data; |
1435 | |
1436 | /* should have been called from irqsafe timer with irq already off */ |
1437 | __queue_work(dwork->cpu, dwork->wq, &dwork->work); |
1438 | } |
1439 | EXPORT_SYMBOL(delayed_work_timer_fn); |
1440 | |
1441 | static void __queue_delayed_work(int cpu, struct workqueue_struct *wq, |
1442 | struct delayed_work *dwork, unsigned long delay) |
1443 | { |
1444 | struct timer_list *timer = &dwork->timer; |
1445 | struct work_struct *work = &dwork->work; |
1446 | |
1447 | WARN_ON_ONCE(timer->function != delayed_work_timer_fn || |
1448 | timer->data != (unsigned long)dwork); |
1449 | WARN_ON_ONCE(timer_pending(timer)); |
1450 | WARN_ON_ONCE(!list_empty(&work->entry)); |
1451 | |
1452 | /* |
1453 | * If @delay is 0, queue @dwork->work immediately. This is for |
1454 | * both optimization and correctness. The earliest @timer can |
1455 | * expire is on the closest next tick and delayed_work users depend |
1456 | * on that there's no such delay when @delay is 0. |
1457 | */ |
1458 | if (!delay) { |
1459 | __queue_work(cpu, wq, &dwork->work); |
1460 | return; |
1461 | } |
1462 | |
1463 | timer_stats_timer_set_start_info(&dwork->timer); |
1464 | |
1465 | dwork->wq = wq; |
1466 | dwork->cpu = cpu; |
1467 | timer->expires = jiffies + delay; |
1468 | |
1469 | if (unlikely(cpu != WORK_CPU_UNBOUND)) |
1470 | add_timer_on(timer, cpu); |
1471 | else |
1472 | add_timer(timer); |
1473 | } |
1474 | |
1475 | /** |
1476 | * queue_delayed_work_on - queue work on specific CPU after delay |
1477 | * @cpu: CPU number to execute work on |
1478 | * @wq: workqueue to use |
1479 | * @dwork: work to queue |
1480 | * @delay: number of jiffies to wait before queueing |
1481 | * |
1482 | * Return: %false if @work was already on a queue, %true otherwise. If |
1483 | * @delay is zero and @dwork is idle, it will be scheduled for immediate |
1484 | * execution. |
1485 | */ |
1486 | bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq, |
1487 | struct delayed_work *dwork, unsigned long delay) |
1488 | { |
1489 | struct work_struct *work = &dwork->work; |
1490 | bool ret = false; |
1491 | unsigned long flags; |
1492 | |
1493 | /* read the comment in __queue_work() */ |
1494 | local_irq_save(flags); |
1495 | |
1496 | if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) { |
1497 | __queue_delayed_work(cpu, wq, dwork, delay); |
1498 | ret = true; |
1499 | } |
1500 | |
1501 | local_irq_restore(flags); |
1502 | return ret; |
1503 | } |
1504 | EXPORT_SYMBOL(queue_delayed_work_on); |
1505 | |
1506 | /** |
1507 | * mod_delayed_work_on - modify delay of or queue a delayed work on specific CPU |
1508 | * @cpu: CPU number to execute work on |
1509 | * @wq: workqueue to use |
1510 | * @dwork: work to queue |
1511 | * @delay: number of jiffies to wait before queueing |
1512 | * |
1513 | * If @dwork is idle, equivalent to queue_delayed_work_on(); otherwise, |
1514 | * modify @dwork's timer so that it expires after @delay. If @delay is |
1515 | * zero, @work is guaranteed to be scheduled immediately regardless of its |
1516 | * current state. |
1517 | * |
1518 | * Return: %false if @dwork was idle and queued, %true if @dwork was |
1519 | * pending and its timer was modified. |
1520 | * |
1521 | * This function is safe to call from any context including IRQ handler. |
1522 | * See try_to_grab_pending() for details. |
1523 | */ |
1524 | bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq, |
1525 | struct delayed_work *dwork, unsigned long delay) |
1526 | { |
1527 | unsigned long flags; |
1528 | int ret; |
1529 | |
1530 | do { |
1531 | ret = try_to_grab_pending(&dwork->work, true, &flags); |
1532 | } while (unlikely(ret == -EAGAIN)); |
1533 | |
1534 | if (likely(ret >= 0)) { |
1535 | __queue_delayed_work(cpu, wq, dwork, delay); |
1536 | local_irq_restore(flags); |
1537 | } |
1538 | |
1539 | /* -ENOENT from try_to_grab_pending() becomes %true */ |
1540 | return ret; |
1541 | } |
1542 | EXPORT_SYMBOL_GPL(mod_delayed_work_on); |
1543 | |
1544 | /** |
1545 | * worker_enter_idle - enter idle state |
1546 | * @worker: worker which is entering idle state |
1547 | * |
1548 | * @worker is entering idle state. Update stats and idle timer if |
1549 | * necessary. |
1550 | * |
1551 | * LOCKING: |
1552 | * spin_lock_irq(pool->lock). |
1553 | */ |
1554 | static void worker_enter_idle(struct worker *worker) |
1555 | { |
1556 | struct worker_pool *pool = worker->pool; |
1557 | |
1558 | if (WARN_ON_ONCE(worker->flags & WORKER_IDLE) || |
1559 | WARN_ON_ONCE(!list_empty(&worker->entry) && |
1560 | (worker->hentry.next || worker->hentry.pprev))) |
1561 | return; |
1562 | |
1563 | /* can't use worker_set_flags(), also called from start_worker() */ |
1564 | worker->flags |= WORKER_IDLE; |
1565 | pool->nr_idle++; |
1566 | worker->last_active = jiffies; |
1567 | |
1568 | /* idle_list is LIFO */ |
1569 | list_add(&worker->entry, &pool->idle_list); |
1570 | |
1571 | if (too_many_workers(pool) && !timer_pending(&pool->idle_timer)) |
1572 | mod_timer(&pool->idle_timer, jiffies + IDLE_WORKER_TIMEOUT); |
1573 | |
1574 | /* |
1575 | * Sanity check nr_running. Because wq_unbind_fn() releases |
1576 | * pool->lock between setting %WORKER_UNBOUND and zapping |
1577 | * nr_running, the warning may trigger spuriously. Check iff |
1578 | * unbind is not in progress. |
1579 | */ |
1580 | WARN_ON_ONCE(!(pool->flags & POOL_DISASSOCIATED) && |
1581 | pool->nr_workers == pool->nr_idle && |
1582 | atomic_read(&pool->nr_running)); |
1583 | } |
1584 | |
1585 | /** |
1586 | * worker_leave_idle - leave idle state |
1587 | * @worker: worker which is leaving idle state |
1588 | * |
1589 | * @worker is leaving idle state. Update stats. |
1590 | * |
1591 | * LOCKING: |
1592 | * spin_lock_irq(pool->lock). |
1593 | */ |
1594 | static void worker_leave_idle(struct worker *worker) |
1595 | { |
1596 | struct worker_pool *pool = worker->pool; |
1597 | |
1598 | if (WARN_ON_ONCE(!(worker->flags & WORKER_IDLE))) |
1599 | return; |
1600 | worker_clr_flags(worker, WORKER_IDLE); |
1601 | pool->nr_idle--; |
1602 | list_del_init(&worker->entry); |
1603 | } |
1604 | |
1605 | static struct worker *alloc_worker(void) |
1606 | { |
1607 | struct worker *worker; |
1608 | |
1609 | worker = kzalloc(sizeof(*worker), GFP_KERNEL); |
1610 | if (worker) { |
1611 | INIT_LIST_HEAD(&worker->entry); |
1612 | INIT_LIST_HEAD(&worker->scheduled); |
1613 | INIT_LIST_HEAD(&worker->node); |
1614 | /* on creation a worker is in !idle && prep state */ |
1615 | worker->flags = WORKER_PREP; |
1616 | } |
1617 | return worker; |
1618 | } |
1619 | |
1620 | /** |
1621 | * worker_attach_to_pool() - attach a worker to a pool |
1622 | * @worker: worker to be attached |
1623 | * @pool: the target pool |
1624 | * |
1625 | * Attach @worker to @pool. Once attached, the %WORKER_UNBOUND flag and |
1626 | * cpu-binding of @worker are kept coordinated with the pool across |
1627 | * cpu-[un]hotplugs. |
1628 | */ |
1629 | static void worker_attach_to_pool(struct worker *worker, |
1630 | struct worker_pool *pool) |
1631 | { |
1632 | mutex_lock(&pool->attach_mutex); |
1633 | |
1634 | /* |
1635 | * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any |
1636 | * online CPUs. It'll be re-applied when any of the CPUs come up. |
1637 | */ |
1638 | set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); |
1639 | |
1640 | /* |
1641 | * The pool->attach_mutex ensures %POOL_DISASSOCIATED remains |
1642 | * stable across this function. See the comments above the |
1643 | * flag definition for details. |
1644 | */ |
1645 | if (pool->flags & POOL_DISASSOCIATED) |
1646 | worker->flags |= WORKER_UNBOUND; |
1647 | |
1648 | list_add_tail(&worker->node, &pool->workers); |
1649 | |
1650 | mutex_unlock(&pool->attach_mutex); |
1651 | } |
1652 | |
1653 | /** |
1654 | * worker_detach_from_pool() - detach a worker from its pool |
1655 | * @worker: worker which is attached to its pool |
1656 | * @pool: the pool @worker is attached to |
1657 | * |
1658 | * Undo the attaching which had been done in worker_attach_to_pool(). The |
1659 | * caller worker shouldn't access to the pool after detached except it has |
1660 | * other reference to the pool. |
1661 | */ |
1662 | static void worker_detach_from_pool(struct worker *worker, |
1663 | struct worker_pool *pool) |
1664 | { |
1665 | struct completion *detach_completion = NULL; |
1666 | |
1667 | mutex_lock(&pool->attach_mutex); |
1668 | list_del(&worker->node); |
1669 | if (list_empty(&pool->workers)) |
1670 | detach_completion = pool->detach_completion; |
1671 | mutex_unlock(&pool->attach_mutex); |
1672 | |
1673 | if (detach_completion) |
1674 | complete(detach_completion); |
1675 | } |
1676 | |
1677 | /** |
1678 | * create_worker - create a new workqueue worker |
1679 | * @pool: pool the new worker will belong to |
1680 | * |
1681 | * Create a new worker which is attached to @pool. The new worker must be |
1682 | * started by start_worker(). |
1683 | * |
1684 | * CONTEXT: |
1685 | * Might sleep. Does GFP_KERNEL allocations. |
1686 | * |
1687 | * Return: |
1688 | * Pointer to the newly created worker. |
1689 | */ |
1690 | static struct worker *create_worker(struct worker_pool *pool) |
1691 | { |
1692 | struct worker *worker = NULL; |
1693 | int id = -1; |
1694 | char id_buf[16]; |
1695 | |
1696 | /* ID is needed to determine kthread name */ |
1697 | id = ida_simple_get(&pool->worker_ida, 0, 0, GFP_KERNEL); |
1698 | if (id < 0) |
1699 | goto fail; |
1700 | |
1701 | worker = alloc_worker(); |
1702 | if (!worker) |
1703 | goto fail; |
1704 | |
1705 | worker->pool = pool; |
1706 | worker->id = id; |
1707 | |
1708 | if (pool->cpu >= 0) |
1709 | snprintf(id_buf, sizeof(id_buf), "%d:%d%s", pool->cpu, id, |
1710 | pool->attrs->nice < 0 ? "H" : ""); |
1711 | else |
1712 | snprintf(id_buf, sizeof(id_buf), "u%d:%d", pool->id, id); |
1713 | |
1714 | worker->task = kthread_create_on_node(worker_thread, worker, pool->node, |
1715 | "kworker/%s", id_buf); |
1716 | if (IS_ERR(worker->task)) |
1717 | goto fail; |
1718 | |
1719 | set_user_nice(worker->task, pool->attrs->nice); |
1720 | |
1721 | /* prevent userland from meddling with cpumask of workqueue workers */ |
1722 | worker->task->flags |= PF_NO_SETAFFINITY; |
1723 | |
1724 | /* successful, attach the worker to the pool */ |
1725 | worker_attach_to_pool(worker, pool); |
1726 | |
1727 | return worker; |
1728 | |
1729 | fail: |
1730 | if (id >= 0) |
1731 | ida_simple_remove(&pool->worker_ida, id); |
1732 | kfree(worker); |
1733 | return NULL; |
1734 | } |
1735 | |
1736 | /** |
1737 | * start_worker - start a newly created worker |
1738 | * @worker: worker to start |
1739 | * |
1740 | * Make the pool aware of @worker and start it. |
1741 | * |
1742 | * CONTEXT: |
1743 | * spin_lock_irq(pool->lock). |
1744 | */ |
1745 | static void start_worker(struct worker *worker) |
1746 | { |
1747 | worker->pool->nr_workers++; |
1748 | worker_enter_idle(worker); |
1749 | wake_up_process(worker->task); |
1750 | } |
1751 | |
1752 | /** |
1753 | * create_and_start_worker - create and start a worker for a pool |
1754 | * @pool: the target pool |
1755 | * |
1756 | * Grab the managership of @pool and create and start a new worker for it. |
1757 | * |
1758 | * Return: 0 on success. A negative error code otherwise. |
1759 | */ |
1760 | static int create_and_start_worker(struct worker_pool *pool) |
1761 | { |
1762 | struct worker *worker; |
1763 | |
1764 | worker = create_worker(pool); |
1765 | if (worker) { |
1766 | spin_lock_irq(&pool->lock); |
1767 | start_worker(worker); |
1768 | spin_unlock_irq(&pool->lock); |
1769 | } |
1770 | |
1771 | return worker ? 0 : -ENOMEM; |
1772 | } |
1773 | |
1774 | /** |
1775 | * destroy_worker - destroy a workqueue worker |
1776 | * @worker: worker to be destroyed |
1777 | * |
1778 | * Destroy @worker and adjust @pool stats accordingly. The worker should |
1779 | * be idle. |
1780 | * |
1781 | * CONTEXT: |
1782 | * spin_lock_irq(pool->lock). |
1783 | */ |
1784 | static void destroy_worker(struct worker *worker) |
1785 | { |
1786 | struct worker_pool *pool = worker->pool; |
1787 | |
1788 | lockdep_assert_held(&pool->lock); |
1789 | |
1790 | /* sanity check frenzy */ |
1791 | if (WARN_ON(worker->current_work) || |
1792 | WARN_ON(!list_empty(&worker->scheduled)) || |
1793 | WARN_ON(!(worker->flags & WORKER_IDLE))) |
1794 | return; |
1795 | |
1796 | pool->nr_workers--; |
1797 | pool->nr_idle--; |
1798 | |
1799 | list_del_init(&worker->entry); |
1800 | worker->flags |= WORKER_DIE; |
1801 | wake_up_process(worker->task); |
1802 | } |
1803 | |
1804 | static void idle_worker_timeout(unsigned long __pool) |
1805 | { |
1806 | struct worker_pool *pool = (void *)__pool; |
1807 | |
1808 | spin_lock_irq(&pool->lock); |
1809 | |
1810 | while (too_many_workers(pool)) { |
1811 | struct worker *worker; |
1812 | unsigned long expires; |
1813 | |
1814 | /* idle_list is kept in LIFO order, check the last one */ |
1815 | worker = list_entry(pool->idle_list.prev, struct worker, entry); |
1816 | expires = worker->last_active + IDLE_WORKER_TIMEOUT; |
1817 | |
1818 | if (time_before(jiffies, expires)) { |
1819 | mod_timer(&pool->idle_timer, expires); |
1820 | break; |
1821 | } |
1822 | |
1823 | destroy_worker(worker); |
1824 | } |
1825 | |
1826 | spin_unlock_irq(&pool->lock); |
1827 | } |
1828 | |
1829 | static void send_mayday(struct work_struct *work) |
1830 | { |
1831 | struct pool_workqueue *pwq = get_work_pwq(work); |
1832 | struct workqueue_struct *wq = pwq->wq; |
1833 | |
1834 | lockdep_assert_held(&wq_mayday_lock); |
1835 | |
1836 | if (!wq->rescuer) |
1837 | return; |
1838 | |
1839 | /* mayday mayday mayday */ |
1840 | if (list_empty(&pwq->mayday_node)) { |
1841 | /* |
1842 | * If @pwq is for an unbound wq, its base ref may be put at |
1843 | * any time due to an attribute change. Pin @pwq until the |
1844 | * rescuer is done with it. |
1845 | */ |
1846 | get_pwq(pwq); |
1847 | list_add_tail(&pwq->mayday_node, &wq->maydays); |
1848 | wake_up_process(wq->rescuer->task); |
1849 | } |
1850 | } |
1851 | |
1852 | static void pool_mayday_timeout(unsigned long __pool) |
1853 | { |
1854 | struct worker_pool *pool = (void *)__pool; |
1855 | struct work_struct *work; |
1856 | |
1857 | spin_lock_irq(&wq_mayday_lock); /* for wq->maydays */ |
1858 | spin_lock(&pool->lock); |
1859 | |
1860 | if (need_to_create_worker(pool)) { |
1861 | /* |
1862 | * We've been trying to create a new worker but |
1863 | * haven't been successful. We might be hitting an |
1864 | * allocation deadlock. Send distress signals to |
1865 | * rescuers. |
1866 | */ |
1867 | list_for_each_entry(work, &pool->worklist, entry) |
1868 | send_mayday(work); |
1869 | } |
1870 | |
1871 | spin_unlock(&pool->lock); |
1872 | spin_unlock_irq(&wq_mayday_lock); |
1873 | |
1874 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL); |
1875 | } |
1876 | |
1877 | /** |
1878 | * maybe_create_worker - create a new worker if necessary |
1879 | * @pool: pool to create a new worker for |
1880 | * |
1881 | * Create a new worker for @pool if necessary. @pool is guaranteed to |
1882 | * have at least one idle worker on return from this function. If |
1883 | * creating a new worker takes longer than MAYDAY_INTERVAL, mayday is |
1884 | * sent to all rescuers with works scheduled on @pool to resolve |
1885 | * possible allocation deadlock. |
1886 | * |
1887 | * On return, need_to_create_worker() is guaranteed to be %false and |
1888 | * may_start_working() %true. |
1889 | * |
1890 | * LOCKING: |
1891 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
1892 | * multiple times. Does GFP_KERNEL allocations. Called only from |
1893 | * manager. |
1894 | * |
1895 | * Return: |
1896 | * %false if no action was taken and pool->lock stayed locked, %true |
1897 | * otherwise. |
1898 | */ |
1899 | static bool maybe_create_worker(struct worker_pool *pool) |
1900 | __releases(&pool->lock) |
1901 | __acquires(&pool->lock) |
1902 | { |
1903 | if (!need_to_create_worker(pool)) |
1904 | return false; |
1905 | restart: |
1906 | spin_unlock_irq(&pool->lock); |
1907 | |
1908 | /* if we don't make progress in MAYDAY_INITIAL_TIMEOUT, call for help */ |
1909 | mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INITIAL_TIMEOUT); |
1910 | |
1911 | while (true) { |
1912 | struct worker *worker; |
1913 | |
1914 | worker = create_worker(pool); |
1915 | if (worker) { |
1916 | del_timer_sync(&pool->mayday_timer); |
1917 | spin_lock_irq(&pool->lock); |
1918 | start_worker(worker); |
1919 | if (WARN_ON_ONCE(need_to_create_worker(pool))) |
1920 | goto restart; |
1921 | return true; |
1922 | } |
1923 | |
1924 | if (!need_to_create_worker(pool)) |
1925 | break; |
1926 | |
1927 | __set_current_state(TASK_INTERRUPTIBLE); |
1928 | schedule_timeout(CREATE_COOLDOWN); |
1929 | |
1930 | if (!need_to_create_worker(pool)) |
1931 | break; |
1932 | } |
1933 | |
1934 | del_timer_sync(&pool->mayday_timer); |
1935 | spin_lock_irq(&pool->lock); |
1936 | if (need_to_create_worker(pool)) |
1937 | goto restart; |
1938 | return true; |
1939 | } |
1940 | |
1941 | /** |
1942 | * manage_workers - manage worker pool |
1943 | * @worker: self |
1944 | * |
1945 | * Assume the manager role and manage the worker pool @worker belongs |
1946 | * to. At any given time, there can be only zero or one manager per |
1947 | * pool. The exclusion is handled automatically by this function. |
1948 | * |
1949 | * The caller can safely start processing works on false return. On |
1950 | * true return, it's guaranteed that need_to_create_worker() is false |
1951 | * and may_start_working() is true. |
1952 | * |
1953 | * CONTEXT: |
1954 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
1955 | * multiple times. Does GFP_KERNEL allocations. |
1956 | * |
1957 | * Return: |
1958 | * %false if the pool don't need management and the caller can safely start |
1959 | * processing works, %true indicates that the function released pool->lock |
1960 | * and reacquired it to perform some management function and that the |
1961 | * conditions that the caller verified while holding the lock before |
1962 | * calling the function might no longer be true. |
1963 | */ |
1964 | static bool manage_workers(struct worker *worker) |
1965 | { |
1966 | struct worker_pool *pool = worker->pool; |
1967 | bool ret = false; |
1968 | |
1969 | /* |
1970 | * Anyone who successfully grabs manager_arb wins the arbitration |
1971 | * and becomes the manager. mutex_trylock() on pool->manager_arb |
1972 | * failure while holding pool->lock reliably indicates that someone |
1973 | * else is managing the pool and the worker which failed trylock |
1974 | * can proceed to executing work items. This means that anyone |
1975 | * grabbing manager_arb is responsible for actually performing |
1976 | * manager duties. If manager_arb is grabbed and released without |
1977 | * actual management, the pool may stall indefinitely. |
1978 | */ |
1979 | if (!mutex_trylock(&pool->manager_arb)) |
1980 | return ret; |
1981 | |
1982 | ret |= maybe_create_worker(pool); |
1983 | |
1984 | mutex_unlock(&pool->manager_arb); |
1985 | return ret; |
1986 | } |
1987 | |
1988 | /** |
1989 | * process_one_work - process single work |
1990 | * @worker: self |
1991 | * @work: work to process |
1992 | * |
1993 | * Process @work. This function contains all the logics necessary to |
1994 | * process a single work including synchronization against and |
1995 | * interaction with other workers on the same cpu, queueing and |
1996 | * flushing. As long as context requirement is met, any worker can |
1997 | * call this function to process a work. |
1998 | * |
1999 | * CONTEXT: |
2000 | * spin_lock_irq(pool->lock) which is released and regrabbed. |
2001 | */ |
2002 | static void process_one_work(struct worker *worker, struct work_struct *work) |
2003 | __releases(&pool->lock) |
2004 | __acquires(&pool->lock) |
2005 | { |
2006 | struct pool_workqueue *pwq = get_work_pwq(work); |
2007 | struct worker_pool *pool = worker->pool; |
2008 | bool cpu_intensive = pwq->wq->flags & WQ_CPU_INTENSIVE; |
2009 | int work_color; |
2010 | struct worker *collision; |
2011 | #ifdef CONFIG_LOCKDEP |
2012 | /* |
2013 | * It is permissible to free the struct work_struct from |
2014 | * inside the function that is called from it, this we need to |
2015 | * take into account for lockdep too. To avoid bogus "held |
2016 | * lock freed" warnings as well as problems when looking into |
2017 | * work->lockdep_map, make a copy and use that here. |
2018 | */ |
2019 | struct lockdep_map lockdep_map; |
2020 | |
2021 | lockdep_copy_map(&lockdep_map, &work->lockdep_map); |
2022 | #endif |
2023 | /* |
2024 | * Ensure we're on the correct CPU. DISASSOCIATED test is |
2025 | * necessary to avoid spurious warnings from rescuers servicing the |
2026 | * unbound or a disassociated pool. |
2027 | */ |
2028 | WARN_ON_ONCE(!(worker->flags & WORKER_UNBOUND) && |
2029 | !(pool->flags & POOL_DISASSOCIATED) && |
2030 | raw_smp_processor_id() != pool->cpu); |
2031 | |
2032 | /* |
2033 | * A single work shouldn't be executed concurrently by |
2034 | * multiple workers on a single cpu. Check whether anyone is |
2035 | * already processing the work. If so, defer the work to the |
2036 | * currently executing one. |
2037 | */ |
2038 | collision = find_worker_executing_work(pool, work); |
2039 | if (unlikely(collision)) { |
2040 | move_linked_works(work, &collision->scheduled, NULL); |
2041 | return; |
2042 | } |
2043 | |
2044 | /* claim and dequeue */ |
2045 | debug_work_deactivate(work); |
2046 | hash_add(pool->busy_hash, &worker->hentry, (unsigned long)work); |
2047 | worker->current_work = work; |
2048 | worker->current_func = work->func; |
2049 | worker->current_pwq = pwq; |
2050 | work_color = get_work_color(work); |
2051 | |
2052 | list_del_init(&work->entry); |
2053 | |
2054 | /* |
2055 | * CPU intensive works don't participate in concurrency |
2056 | * management. They're the scheduler's responsibility. |
2057 | */ |
2058 | if (unlikely(cpu_intensive)) |
2059 | worker_set_flags(worker, WORKER_CPU_INTENSIVE, true); |
2060 | |
2061 | /* |
2062 | * Unbound pool isn't concurrency managed and work items should be |
2063 | * executed ASAP. Wake up another worker if necessary. |
2064 | */ |
2065 | if ((worker->flags & WORKER_UNBOUND) && need_more_worker(pool)) |
2066 | wake_up_worker(pool); |
2067 | |
2068 | /* |
2069 | * Record the last pool and clear PENDING which should be the last |
2070 | * update to @work. Also, do this inside @pool->lock so that |
2071 | * PENDING and queued state changes happen together while IRQ is |
2072 | * disabled. |
2073 | */ |
2074 | set_work_pool_and_clear_pending(work, pool->id); |
2075 | |
2076 | spin_unlock_irq(&pool->lock); |
2077 | |
2078 | lock_map_acquire_read(&pwq->wq->lockdep_map); |
2079 | lock_map_acquire(&lockdep_map); |
2080 | trace_workqueue_execute_start(work); |
2081 | worker->current_func(work); |
2082 | /* |
2083 | * While we must be careful to not use "work" after this, the trace |
2084 | * point will only record its address. |
2085 | */ |
2086 | trace_workqueue_execute_end(work); |
2087 | lock_map_release(&lockdep_map); |
2088 | lock_map_release(&pwq->wq->lockdep_map); |
2089 | |
2090 | if (unlikely(in_atomic() || lockdep_depth(current) > 0)) { |
2091 | pr_err("BUG: workqueue leaked lock or atomic: %s/0x%08x/%d\n" |
2092 | " last function: %pf\n", |
2093 | current->comm, preempt_count(), task_pid_nr(current), |
2094 | worker->current_func); |
2095 | debug_show_held_locks(current); |
2096 | dump_stack(); |
2097 | } |
2098 | |
2099 | /* |
2100 | * The following prevents a kworker from hogging CPU on !PREEMPT |
2101 | * kernels, where a requeueing work item waiting for something to |
2102 | * happen could deadlock with stop_machine as such work item could |
2103 | * indefinitely requeue itself while all other CPUs are trapped in |
2104 | * stop_machine. |
2105 | */ |
2106 | cond_resched(); |
2107 | |
2108 | spin_lock_irq(&pool->lock); |
2109 | |
2110 | /* clear cpu intensive status */ |
2111 | if (unlikely(cpu_intensive)) |
2112 | worker_clr_flags(worker, WORKER_CPU_INTENSIVE); |
2113 | |
2114 | /* we're done with it, release */ |
2115 | hash_del(&worker->hentry); |
2116 | worker->current_work = NULL; |
2117 | worker->current_func = NULL; |
2118 | worker->current_pwq = NULL; |
2119 | worker->desc_valid = false; |
2120 | pwq_dec_nr_in_flight(pwq, work_color); |
2121 | } |
2122 | |
2123 | /** |
2124 | * process_scheduled_works - process scheduled works |
2125 | * @worker: self |
2126 | * |
2127 | * Process all scheduled works. Please note that the scheduled list |
2128 | * may change while processing a work, so this function repeatedly |
2129 | * fetches a work from the top and executes it. |
2130 | * |
2131 | * CONTEXT: |
2132 | * spin_lock_irq(pool->lock) which may be released and regrabbed |
2133 | * multiple times. |
2134 | */ |
2135 | static void process_scheduled_works(struct worker *worker) |
2136 | { |
2137 | while (!list_empty(&worker->scheduled)) { |
2138 | struct work_struct *work = list_first_entry(&worker->scheduled, |
2139 | struct work_struct, entry); |
2140 | process_one_work(worker, work); |
2141 | } |
2142 | } |
2143 | |
2144 | /** |
2145 | * worker_thread - the worker thread function |
2146 | * @__worker: self |
2147 | * |
2148 | * The worker thread function. All workers belong to a worker_pool - |
2149 | * either a per-cpu one or dynamic unbound one. These workers process all |
2150 | * work items regardless of their specific target workqueue. The only |
2151 | * exception is work items which belong to workqueues with a rescuer which |
2152 | * will be explained in rescuer_thread(). |
2153 | * |
2154 | * Return: 0 |
2155 | */ |
2156 | static int worker_thread(void *__worker) |
2157 | { |
2158 | struct worker *worker = __worker; |
2159 | struct worker_pool *pool = worker->pool; |
2160 | |
2161 | /* tell the scheduler that this is a workqueue worker */ |
2162 | worker->task->flags |= PF_WQ_WORKER; |
2163 | woke_up: |
2164 | spin_lock_irq(&pool->lock); |
2165 | |
2166 | /* am I supposed to die? */ |
2167 | if (unlikely(worker->flags & WORKER_DIE)) { |
2168 | spin_unlock_irq(&pool->lock); |
2169 | WARN_ON_ONCE(!list_empty(&worker->entry)); |
2170 | worker->task->flags &= ~PF_WQ_WORKER; |
2171 | |
2172 | set_task_comm(worker->task, "kworker/dying"); |
2173 | ida_simple_remove(&pool->worker_ida, worker->id); |
2174 | worker_detach_from_pool(worker, pool); |
2175 | kfree(worker); |
2176 | return 0; |
2177 | } |
2178 | |
2179 | worker_leave_idle(worker); |
2180 | recheck: |
2181 | /* no more worker necessary? */ |
2182 | if (!need_more_worker(pool)) |
2183 | goto sleep; |
2184 | |
2185 | /* do we need to manage? */ |
2186 | if (unlikely(!may_start_working(pool)) && manage_workers(worker)) |
2187 | goto recheck; |
2188 | |
2189 | /* |
2190 | * ->scheduled list can only be filled while a worker is |
2191 | * preparing to process a work or actually processing it. |
2192 | * Make sure nobody diddled with it while I was sleeping. |
2193 | */ |
2194 | WARN_ON_ONCE(!list_empty(&worker->scheduled)); |
2195 | |
2196 | /* |
2197 | * Finish PREP stage. We're guaranteed to have at least one idle |
2198 | * worker or that someone else has already assumed the manager |
2199 | * role. This is where @worker starts participating in concurrency |
2200 | * management if applicable and concurrency management is restored |
2201 | * after being rebound. See rebind_workers() for details. |
2202 | */ |
2203 | worker_clr_flags(worker, WORKER_PREP | WORKER_REBOUND); |
2204 | |
2205 | do { |
2206 | struct work_struct *work = |
2207 | list_first_entry(&pool->worklist, |
2208 | struct work_struct, entry); |
2209 | |
2210 | if (likely(!(*work_data_bits(work) & WORK_STRUCT_LINKED))) { |
2211 | /* optimization path, not strictly necessary */ |
2212 | process_one_work(worker, work); |
2213 | if (unlikely(!list_empty(&worker->scheduled))) |
2214 | process_scheduled_works(worker); |
2215 | } else { |
2216 | move_linked_works(work, &worker->scheduled, NULL); |
2217 | process_scheduled_works(worker); |
2218 | } |
2219 | } while (keep_working(pool)); |
2220 | |
2221 | worker_set_flags(worker, WORKER_PREP, false); |
2222 | sleep: |
2223 | /* |
2224 | * pool->lock is held and there's no work to process and no need to |
2225 | * manage, sleep. Workers are woken up only while holding |
2226 | * pool->lock or from local cpu, so setting the current state |
2227 | * before releasing pool->lock is enough to prevent losing any |
2228 | * event. |
2229 | */ |
2230 | worker_enter_idle(worker); |
2231 | __set_current_state(TASK_INTERRUPTIBLE); |
2232 | spin_unlock_irq(&pool->lock); |
2233 | schedule(); |
2234 | goto woke_up; |
2235 | } |
2236 | |
2237 | /** |
2238 | * rescuer_thread - the rescuer thread function |
2239 | * @__rescuer: self |
2240 | * |
2241 | * Workqueue rescuer thread function. There's one rescuer for each |
2242 | * workqueue which has WQ_MEM_RECLAIM set. |
2243 | * |
2244 | * Regular work processing on a pool may block trying to create a new |
2245 | * worker which uses GFP_KERNEL allocation which has slight chance of |
2246 | * developing into deadlock if some works currently on the same queue |
2247 | * need to be processed to satisfy the GFP_KERNEL allocation. This is |
2248 | * the problem rescuer solves. |
2249 | * |
2250 | * When such condition is possible, the pool summons rescuers of all |
2251 | * workqueues which have works queued on the pool and let them process |
2252 | * those works so that forward progress can be guaranteed. |
2253 | * |
2254 | * This should happen rarely. |
2255 | * |
2256 | * Return: 0 |
2257 | */ |
2258 | static int rescuer_thread(void *__rescuer) |
2259 | { |
2260 | struct worker *rescuer = __rescuer; |
2261 | struct workqueue_struct *wq = rescuer->rescue_wq; |
2262 | struct list_head *scheduled = &rescuer->scheduled; |
2263 | bool should_stop; |
2264 | |
2265 | set_user_nice(current, RESCUER_NICE_LEVEL); |
2266 | |
2267 | /* |
2268 | * Mark rescuer as worker too. As WORKER_PREP is never cleared, it |
2269 | * doesn't participate in concurrency management. |
2270 | */ |
2271 | rescuer->task->flags |= PF_WQ_WORKER; |
2272 | repeat: |
2273 | set_current_state(TASK_INTERRUPTIBLE); |
2274 | |
2275 | /* |
2276 | * By the time the rescuer is requested to stop, the workqueue |
2277 | * shouldn't have any work pending, but @wq->maydays may still have |
2278 | * pwq(s) queued. This can happen by non-rescuer workers consuming |
2279 | * all the work items before the rescuer got to them. Go through |
2280 | * @wq->maydays processing before acting on should_stop so that the |
2281 | * list is always empty on exit. |
2282 | */ |
2283 | should_stop = kthread_should_stop(); |
2284 | |
2285 | /* see whether any pwq is asking for help */ |
2286 | spin_lock_irq(&wq_mayday_lock); |
2287 | |
2288 | while (!list_empty(&wq->maydays)) { |
2289 | struct pool_workqueue *pwq = list_first_entry(&wq->maydays, |
2290 | struct pool_workqueue, mayday_node); |
2291 | struct worker_pool *pool = pwq->pool; |
2292 | struct work_struct *work, *n; |
2293 | |
2294 | __set_current_state(TASK_RUNNING); |
2295 | list_del_init(&pwq->mayday_node); |
2296 | |
2297 | spin_unlock_irq(&wq_mayday_lock); |
2298 | |
2299 | worker_attach_to_pool(rescuer, pool); |
2300 | |
2301 | spin_lock_irq(&pool->lock); |
2302 | rescuer->pool = pool; |
2303 | |
2304 | /* |
2305 | * Slurp in all works issued via this workqueue and |
2306 | * process'em. |
2307 | */ |
2308 | WARN_ON_ONCE(!list_empty(&rescuer->scheduled)); |
2309 | list_for_each_entry_safe(work, n, &pool->worklist, entry) |
2310 | if (get_work_pwq(work) == pwq) |
2311 | move_linked_works(work, scheduled, &n); |
2312 | |
2313 | process_scheduled_works(rescuer); |
2314 | spin_unlock_irq(&pool->lock); |
2315 | |
2316 | worker_detach_from_pool(rescuer, pool); |
2317 | |
2318 | spin_lock_irq(&pool->lock); |
2319 | |
2320 | /* |
2321 | * Put the reference grabbed by send_mayday(). @pool won't |
2322 | * go away while we're holding its lock. |
2323 | */ |
2324 | put_pwq(pwq); |
2325 | |
2326 | /* |
2327 | * Leave this pool. If keep_working() is %true, notify a |
2328 | * regular worker; otherwise, we end up with 0 concurrency |
2329 | * and stalling the execution. |
2330 | */ |
2331 | if (keep_working(pool)) |
2332 | wake_up_worker(pool); |
2333 | |
2334 | rescuer->pool = NULL; |
2335 | spin_unlock(&pool->lock); |
2336 | spin_lock(&wq_mayday_lock); |
2337 | } |
2338 | |
2339 | spin_unlock_irq(&wq_mayday_lock); |
2340 | |
2341 | if (should_stop) { |
2342 | __set_current_state(TASK_RUNNING); |
2343 | rescuer->task->flags &= ~PF_WQ_WORKER; |
2344 | return 0; |
2345 | } |
2346 | |
2347 | /* rescuers should never participate in concurrency management */ |
2348 | WARN_ON_ONCE(!(rescuer->flags & WORKER_NOT_RUNNING)); |
2349 | schedule(); |
2350 | goto repeat; |
2351 | } |
2352 | |
2353 | struct wq_barrier { |
2354 | struct work_struct work; |
2355 | struct completion done; |
2356 | }; |
2357 | |
2358 | static void wq_barrier_func(struct work_struct *work) |
2359 | { |
2360 | struct wq_barrier *barr = container_of(work, struct wq_barrier, work); |
2361 | complete(&barr->done); |
2362 | } |
2363 | |
2364 | /** |
2365 | * insert_wq_barrier - insert a barrier work |
2366 | * @pwq: pwq to insert barrier into |
2367 | * @barr: wq_barrier to insert |
2368 | * @target: target work to attach @barr to |
2369 | * @worker: worker currently executing @target, NULL if @target is not executing |
2370 | * |
2371 | * @barr is linked to @target such that @barr is completed only after |
2372 | * @target finishes execution. Please note that the ordering |
2373 | * guarantee is observed only with respect to @target and on the local |
2374 | * cpu. |
2375 | * |
2376 | * Currently, a queued barrier can't be canceled. This is because |
2377 | * try_to_grab_pending() can't determine whether the work to be |
2378 | * grabbed is at the head of the queue and thus can't clear LINKED |
2379 | * flag of the previous work while there must be a valid next work |
2380 | * after a work with LINKED flag set. |
2381 | * |
2382 | * Note that when @worker is non-NULL, @target may be modified |
2383 | * underneath us, so we can't reliably determine pwq from @target. |
2384 | * |
2385 | * CONTEXT: |
2386 | * spin_lock_irq(pool->lock). |
2387 | */ |
2388 | static void insert_wq_barrier(struct pool_workqueue *pwq, |
2389 | struct wq_barrier *barr, |
2390 | struct work_struct *target, struct worker *worker) |
2391 | { |
2392 | struct list_head *head; |
2393 | unsigned int linked = 0; |
2394 | |
2395 | /* |
2396 | * debugobject calls are safe here even with pool->lock locked |
2397 | * as we know for sure that this will not trigger any of the |
2398 | * checks and call back into the fixup functions where we |
2399 | * might deadlock. |
2400 | */ |
2401 | INIT_WORK_ONSTACK(&barr->work, wq_barrier_func); |
2402 | __set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(&barr->work)); |
2403 | init_completion(&barr->done); |
2404 | |
2405 | /* |
2406 | * If @target is currently being executed, schedule the |
2407 | * barrier to the worker; otherwise, put it after @target. |
2408 | */ |
2409 | if (worker) |
2410 | head = worker->scheduled.next; |
2411 | else { |
2412 | unsigned long *bits = work_data_bits(target); |
2413 | |
2414 | head = target->entry.next; |
2415 | /* there can already be other linked works, inherit and set */ |
2416 | linked = *bits & WORK_STRUCT_LINKED; |
2417 | __set_bit(WORK_STRUCT_LINKED_BIT, bits); |
2418 | } |
2419 | |
2420 | debug_work_activate(&barr->work); |
2421 | insert_work(pwq, &barr->work, head, |
2422 | work_color_to_flags(WORK_NO_COLOR) | linked); |
2423 | } |
2424 | |
2425 | /** |
2426 | * flush_workqueue_prep_pwqs - prepare pwqs for workqueue flushing |
2427 | * @wq: workqueue being flushed |
2428 | * @flush_color: new flush color, < 0 for no-op |
2429 | * @work_color: new work color, < 0 for no-op |
2430 | * |
2431 | * Prepare pwqs for workqueue flushing. |
2432 | * |
2433 | * If @flush_color is non-negative, flush_color on all pwqs should be |
2434 | * -1. If no pwq has in-flight commands at the specified color, all |
2435 | * pwq->flush_color's stay at -1 and %false is returned. If any pwq |
2436 | * has in flight commands, its pwq->flush_color is set to |
2437 | * @flush_color, @wq->nr_pwqs_to_flush is updated accordingly, pwq |
2438 | * wakeup logic is armed and %true is returned. |
2439 | * |
2440 | * The caller should have initialized @wq->first_flusher prior to |
2441 | * calling this function with non-negative @flush_color. If |
2442 | * @flush_color is negative, no flush color update is done and %false |
2443 | * is returned. |
2444 | * |
2445 | * If @work_color is non-negative, all pwqs should have the same |
2446 | * work_color which is previous to @work_color and all will be |
2447 | * advanced to @work_color. |
2448 | * |
2449 | * CONTEXT: |
2450 | * mutex_lock(wq->mutex). |
2451 | * |
2452 | * Return: |
2453 | * %true if @flush_color >= 0 and there's something to flush. %false |
2454 | * otherwise. |
2455 | */ |
2456 | static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq, |
2457 | int flush_color, int work_color) |
2458 | { |
2459 | bool wait = false; |
2460 | struct pool_workqueue *pwq; |
2461 | |
2462 | if (flush_color >= 0) { |
2463 | WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush)); |
2464 | atomic_set(&wq->nr_pwqs_to_flush, 1); |
2465 | } |
2466 | |
2467 | for_each_pwq(pwq, wq) { |
2468 | struct worker_pool *pool = pwq->pool; |
2469 | |
2470 | spin_lock_irq(&pool->lock); |
2471 | |
2472 | if (flush_color >= 0) { |
2473 | WARN_ON_ONCE(pwq->flush_color != -1); |
2474 | |
2475 | if (pwq->nr_in_flight[flush_color]) { |
2476 | pwq->flush_color = flush_color; |
2477 | atomic_inc(&wq->nr_pwqs_to_flush); |
2478 | wait = true; |
2479 | } |
2480 | } |
2481 | |
2482 | if (work_color >= 0) { |
2483 | WARN_ON_ONCE(work_color != work_next_color(pwq->work_color)); |
2484 | pwq->work_color = work_color; |
2485 | } |
2486 | |
2487 | spin_unlock_irq(&pool->lock); |
2488 | } |
2489 | |
2490 | if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush)) |
2491 | complete(&wq->first_flusher->done); |
2492 | |
2493 | return wait; |
2494 | } |
2495 | |
2496 | /** |
2497 | * flush_workqueue - ensure that any scheduled work has run to completion. |
2498 | * @wq: workqueue to flush |
2499 | * |
2500 | * This function sleeps until all work items which were queued on entry |
2501 | * have finished execution, but it is not livelocked by new incoming ones. |
2502 | */ |
2503 | void flush_workqueue(struct workqueue_struct *wq) |
2504 | { |
2505 | struct wq_flusher this_flusher = { |
2506 | .list = LIST_HEAD_INIT(this_flusher.list), |
2507 | .flush_color = -1, |
2508 | .done = COMPLETION_INITIALIZER_ONSTACK(this_flusher.done), |
2509 | }; |
2510 | int next_color; |
2511 | |
2512 | lock_map_acquire(&wq->lockdep_map); |
2513 | lock_map_release(&wq->lockdep_map); |
2514 | |
2515 | mutex_lock(&wq->mutex); |
2516 | |
2517 | /* |
2518 | * Start-to-wait phase |
2519 | */ |
2520 | next_color = work_next_color(wq->work_color); |
2521 | |
2522 | if (next_color != wq->flush_color) { |
2523 | /* |
2524 | * Color space is not full. The current work_color |
2525 | * becomes our flush_color and work_color is advanced |
2526 | * by one. |
2527 | */ |
2528 | WARN_ON_ONCE(!list_empty(&wq->flusher_overflow)); |
2529 | this_flusher.flush_color = wq->work_color; |
2530 | wq->work_color = next_color; |
2531 | |
2532 | if (!wq->first_flusher) { |
2533 | /* no flush in progress, become the first flusher */ |
2534 | WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); |
2535 | |
2536 | wq->first_flusher = &this_flusher; |
2537 | |
2538 | if (!flush_workqueue_prep_pwqs(wq, wq->flush_color, |
2539 | wq->work_color)) { |
2540 | /* nothing to flush, done */ |
2541 | wq->flush_color = next_color; |
2542 | wq->first_flusher = NULL; |
2543 | goto out_unlock; |
2544 | } |
2545 | } else { |
2546 | /* wait in queue */ |
2547 | WARN_ON_ONCE(wq->flush_color == this_flusher.flush_color); |
2548 | list_add_tail(&this_flusher.list, &wq->flusher_queue); |
2549 | flush_workqueue_prep_pwqs(wq, -1, wq->work_color); |
2550 | } |
2551 | } else { |
2552 | /* |
2553 | * Oops, color space is full, wait on overflow queue. |
2554 | * The next flush completion will assign us |
2555 | * flush_color and transfer to flusher_queue. |
2556 | */ |
2557 | list_add_tail(&this_flusher.list, &wq->flusher_overflow); |
2558 | } |
2559 | |
2560 | mutex_unlock(&wq->mutex); |
2561 | |
2562 | wait_for_completion(&this_flusher.done); |
2563 | |
2564 | /* |
2565 | * Wake-up-and-cascade phase |
2566 | * |
2567 | * First flushers are responsible for cascading flushes and |
2568 | * handling overflow. Non-first flushers can simply return. |
2569 | */ |
2570 | if (wq->first_flusher != &this_flusher) |
2571 | return; |
2572 | |
2573 | mutex_lock(&wq->mutex); |
2574 | |
2575 | /* we might have raced, check again with mutex held */ |
2576 | if (wq->first_flusher != &this_flusher) |
2577 | goto out_unlock; |
2578 | |
2579 | wq->first_flusher = NULL; |
2580 | |
2581 | WARN_ON_ONCE(!list_empty(&this_flusher.list)); |
2582 | WARN_ON_ONCE(wq->flush_color != this_flusher.flush_color); |
2583 | |
2584 | while (true) { |
2585 | struct wq_flusher *next, *tmp; |
2586 | |
2587 | /* complete all the flushers sharing the current flush color */ |
2588 | list_for_each_entry_safe(next, tmp, &wq->flusher_queue, list) { |
2589 | if (next->flush_color != wq->flush_color) |
2590 | break; |
2591 | list_del_init(&next->list); |
2592 | complete(&next->done); |
2593 | } |
2594 | |
2595 | WARN_ON_ONCE(!list_empty(&wq->flusher_overflow) && |
2596 | wq->flush_color != work_next_color(wq->work_color)); |
2597 | |
2598 | /* this flush_color is finished, advance by one */ |
2599 | wq->flush_color = work_next_color(wq->flush_color); |
2600 | |
2601 | /* one color has been freed, handle overflow queue */ |
2602 | if (!list_empty(&wq->flusher_overflow)) { |
2603 | /* |
2604 | * Assign the same color to all overflowed |
2605 | * flushers, advance work_color and append to |
2606 | * flusher_queue. This is the start-to-wait |
2607 | * phase for these overflowed flushers. |
2608 | */ |
2609 | list_for_each_entry(tmp, &wq->flusher_overflow, list) |
2610 | tmp->flush_color = wq->work_color; |
2611 | |
2612 | wq->work_color = work_next_color(wq->work_color); |
2613 | |
2614 | list_splice_tail_init(&wq->flusher_overflow, |
2615 | &wq->flusher_queue); |
2616 | flush_workqueue_prep_pwqs(wq, -1, wq->work_color); |
2617 | } |
2618 | |
2619 | if (list_empty(&wq->flusher_queue)) { |
2620 | WARN_ON_ONCE(wq->flush_color != wq->work_color); |
2621 | break; |
2622 | } |
2623 | |
2624 | /* |
2625 | * Need to flush more colors. Make the next flusher |
2626 | * the new first flusher and arm pwqs. |
2627 | */ |
2628 | WARN_ON_ONCE(wq->flush_color == wq->work_color); |
2629 | WARN_ON_ONCE(wq->flush_color != next->flush_color); |
2630 | |
2631 | list_del_init(&next->list); |
2632 | wq->first_flusher = next; |
2633 | |
2634 | if (flush_workqueue_prep_pwqs(wq, wq->flush_color, -1)) |
2635 | break; |
2636 | |
2637 | /* |
2638 | * Meh... this color is already done, clear first |
2639 | * flusher and repeat cascading. |
2640 | */ |
2641 | wq->first_flusher = NULL; |
2642 | } |
2643 | |
2644 | out_unlock: |
2645 | mutex_unlock(&wq->mutex); |
2646 | } |
2647 | EXPORT_SYMBOL_GPL(flush_workqueue); |
2648 | |
2649 | /** |
2650 | * drain_workqueue - drain a workqueue |
2651 | * @wq: workqueue to drain |
2652 | * |
2653 | * Wait until the workqueue becomes empty. While draining is in progress, |
2654 | * only chain queueing is allowed. IOW, only currently pending or running |
2655 | * work items on @wq can queue further work items on it. @wq is flushed |
2656 | * repeatedly until it becomes empty. The number of flushing is detemined |
2657 | * by the depth of chaining and should be relatively short. Whine if it |
2658 | * takes too long. |
2659 | */ |
2660 | void drain_workqueue(struct workqueue_struct *wq) |
2661 | { |
2662 | unsigned int flush_cnt = 0; |
2663 | struct pool_workqueue *pwq; |
2664 | |
2665 | /* |
2666 | * __queue_work() needs to test whether there are drainers, is much |
2667 | * hotter than drain_workqueue() and already looks at @wq->flags. |
2668 | * Use __WQ_DRAINING so that queue doesn't have to check nr_drainers. |
2669 | */ |
2670 | mutex_lock(&wq->mutex); |
2671 | if (!wq->nr_drainers++) |
2672 | wq->flags |= __WQ_DRAINING; |
2673 | mutex_unlock(&wq->mutex); |
2674 | reflush: |
2675 | flush_workqueue(wq); |
2676 | |
2677 | mutex_lock(&wq->mutex); |
2678 | |
2679 | for_each_pwq(pwq, wq) { |
2680 | bool drained; |
2681 | |
2682 | spin_lock_irq(&pwq->pool->lock); |
2683 | drained = !pwq->nr_active && list_empty(&pwq->delayed_works); |
2684 | spin_unlock_irq(&pwq->pool->lock); |
2685 | |
2686 | if (drained) |
2687 | continue; |
2688 | |
2689 | if (++flush_cnt == 10 || |
2690 | (flush_cnt % 100 == 0 && flush_cnt <= 1000)) |
2691 | pr_warn("workqueue %s: drain_workqueue() isn't complete after %u tries\n", |
2692 | wq->name, flush_cnt); |
2693 | |
2694 | mutex_unlock(&wq->mutex); |
2695 | goto reflush; |
2696 | } |
2697 | |
2698 | if (!--wq->nr_drainers) |
2699 | wq->flags &= ~__WQ_DRAINING; |
2700 | mutex_unlock(&wq->mutex); |
2701 | } |
2702 | EXPORT_SYMBOL_GPL(drain_workqueue); |
2703 | |
2704 | static bool start_flush_work(struct work_struct *work, struct wq_barrier *barr) |
2705 | { |
2706 | struct worker *worker = NULL; |
2707 | struct worker_pool *pool; |
2708 | struct pool_workqueue *pwq; |
2709 | |
2710 | might_sleep(); |
2711 | |
2712 | local_irq_disable(); |
2713 | pool = get_work_pool(work); |
2714 | if (!pool) { |
2715 | local_irq_enable(); |
2716 | return false; |
2717 | } |
2718 | |
2719 | spin_lock(&pool->lock); |
2720 | /* see the comment in try_to_grab_pending() with the same code */ |
2721 | pwq = get_work_pwq(work); |
2722 | if (pwq) { |
2723 | if (unlikely(pwq->pool != pool)) |
2724 | goto already_gone; |
2725 | } else { |
2726 | worker = find_worker_executing_work(pool, work); |
2727 | if (!worker) |
2728 | goto already_gone; |
2729 | pwq = worker->current_pwq; |
2730 | } |
2731 | |
2732 | insert_wq_barrier(pwq, barr, work, worker); |
2733 | spin_unlock_irq(&pool->lock); |
2734 | |
2735 | /* |
2736 | * If @max_active is 1 or rescuer is in use, flushing another work |
2737 | * item on the same workqueue may lead to deadlock. Make sure the |
2738 | * flusher is not running on the same workqueue by verifying write |
2739 | * access. |
2740 | */ |
2741 | if (pwq->wq->saved_max_active == 1 || pwq->wq->rescuer) |
2742 | lock_map_acquire(&pwq->wq->lockdep_map); |
2743 | else |
2744 | lock_map_acquire_read(&pwq->wq->lockdep_map); |
2745 | lock_map_release(&pwq->wq->lockdep_map); |
2746 | |
2747 | return true; |
2748 | already_gone: |
2749 | spin_unlock_irq(&pool->lock); |
2750 | return false; |
2751 | } |
2752 | |
2753 | /** |
2754 | * flush_work - wait for a work to finish executing the last queueing instance |
2755 | * @work: the work to flush |
2756 | * |
2757 | * Wait until @work has finished execution. @work is guaranteed to be idle |
2758 | * on return if it hasn't been requeued since flush started. |
2759 | * |
2760 | * Return: |
2761 | * %true if flush_work() waited for the work to finish execution, |
2762 | * %false if it was already idle. |
2763 | */ |
2764 | bool flush_work(struct work_struct *work) |
2765 | { |
2766 | struct wq_barrier barr; |
2767 | |
2768 | lock_map_acquire(&work->lockdep_map); |
2769 | lock_map_release(&work->lockdep_map); |
2770 | |
2771 | if (start_flush_work(work, &barr)) { |
2772 | wait_for_completion(&barr.done); |
2773 | destroy_work_on_stack(&barr.work); |
2774 | return true; |
2775 | } else { |
2776 | return false; |
2777 | } |
2778 | } |
2779 | EXPORT_SYMBOL_GPL(flush_work); |
2780 | |
2781 | static bool __cancel_work_timer(struct work_struct *work, bool is_dwork) |
2782 | { |
2783 | unsigned long flags; |
2784 | int ret; |
2785 | |
2786 | do { |
2787 | ret = try_to_grab_pending(work, is_dwork, &flags); |
2788 | /* |
2789 | * If someone else is canceling, wait for the same event it |
2790 | * would be waiting for before retrying. |
2791 | */ |
2792 | if (unlikely(ret == -ENOENT)) |
2793 | flush_work(work); |
2794 | } while (unlikely(ret < 0)); |
2795 | |
2796 | /* tell other tasks trying to grab @work to back off */ |
2797 | mark_work_canceling(work); |
2798 | local_irq_restore(flags); |
2799 | |
2800 | flush_work(work); |
2801 | clear_work_data(work); |
2802 | return ret; |
2803 | } |
2804 | |
2805 | /** |
2806 | * cancel_work_sync - cancel a work and wait for it to finish |
2807 | * @work: the work to cancel |
2808 | * |
2809 | * Cancel @work and wait for its execution to finish. This function |
2810 | * can be used even if the work re-queues itself or migrates to |
2811 | * another workqueue. On return from this function, @work is |
2812 | * guaranteed to be not pending or executing on any CPU. |
2813 | * |
2814 | * cancel_work_sync(&delayed_work->work) must not be used for |
2815 | * delayed_work's. Use cancel_delayed_work_sync() instead. |
2816 | * |
2817 | * The caller must ensure that the workqueue on which @work was last |
2818 | * queued can't be destroyed before this function returns. |
2819 | * |
2820 | * Return: |
2821 | * %true if @work was pending, %false otherwise. |
2822 | */ |
2823 | bool cancel_work_sync(struct work_struct *work) |
2824 | { |
2825 | return __cancel_work_timer(work, false); |
2826 | } |
2827 | EXPORT_SYMBOL_GPL(cancel_work_sync); |
2828 | |
2829 | /** |
2830 | * flush_delayed_work - wait for a dwork to finish executing the last queueing |
2831 | * @dwork: the delayed work to flush |
2832 | * |
2833 | * Delayed timer is cancelled and the pending work is queued for |
2834 | * immediate execution. Like flush_work(), this function only |
2835 | * considers the last queueing instance of @dwork. |
2836 | * |
2837 | * Return: |
2838 | * %true if flush_work() waited for the work to finish execution, |
2839 | * %false if it was already idle. |
2840 | */ |
2841 | bool flush_delayed_work(struct delayed_work *dwork) |
2842 | { |
2843 | local_irq_disable(); |
2844 | if (del_timer_sync(&dwork->timer)) |
2845 | __queue_work(dwork->cpu, dwork->wq, &dwork->work); |
2846 | local_irq_enable(); |
2847 | return flush_work(&dwork->work); |
2848 | } |
2849 | EXPORT_SYMBOL(flush_delayed_work); |
2850 | |
2851 | /** |
2852 | * cancel_delayed_work - cancel a delayed work |
2853 | * @dwork: delayed_work to cancel |
2854 | * |
2855 | * Kill off a pending delayed_work. |
2856 | * |
2857 | * Return: %true if @dwork was pending and canceled; %false if it wasn't |
2858 | * pending. |
2859 | * |
2860 | * Note: |
2861 | * The work callback function may still be running on return, unless |
2862 | * it returns %true and the work doesn't re-arm itself. Explicitly flush or |
2863 | * use cancel_delayed_work_sync() to wait on it. |
2864 | * |
2865 | * This function is safe to call from any context including IRQ handler. |
2866 | */ |
2867 | bool cancel_delayed_work(struct delayed_work *dwork) |
2868 | { |
2869 | unsigned long flags; |
2870 | int ret; |
2871 | |
2872 | do { |
2873 | ret = try_to_grab_pending(&dwork->work, true, &flags); |
2874 | } while (unlikely(ret == -EAGAIN)); |
2875 | |
2876 | if (unlikely(ret < 0)) |
2877 | return false; |
2878 | |
2879 | set_work_pool_and_clear_pending(&dwork->work, |
2880 | get_work_pool_id(&dwork->work)); |
2881 | local_irq_restore(flags); |
2882 | return ret; |
2883 | } |
2884 | EXPORT_SYMBOL(cancel_delayed_work); |
2885 | |
2886 | /** |
2887 | * cancel_delayed_work_sync - cancel a delayed work and wait for it to finish |
2888 | * @dwork: the delayed work cancel |
2889 | * |
2890 | * This is cancel_work_sync() for delayed works. |
2891 | * |
2892 | * Return: |
2893 | * %true if @dwork was pending, %false otherwise. |
2894 | */ |
2895 | bool cancel_delayed_work_sync(struct delayed_work *dwork) |
2896 | { |
2897 | return __cancel_work_timer(&dwork->work, true); |
2898 | } |
2899 | EXPORT_SYMBOL(cancel_delayed_work_sync); |
2900 | |
2901 | /** |
2902 | * schedule_on_each_cpu - execute a function synchronously on each online CPU |
2903 | * @func: the function to call |
2904 | * |
2905 | * schedule_on_each_cpu() executes @func on each online CPU using the |
2906 | * system workqueue and blocks until all CPUs have completed. |
2907 | * schedule_on_each_cpu() is very slow. |
2908 | * |
2909 | * Return: |
2910 | * 0 on success, -errno on failure. |
2911 | */ |
2912 | int schedule_on_each_cpu(work_func_t func) |
2913 | { |
2914 | int cpu; |
2915 | struct work_struct __percpu *works; |
2916 | |
2917 | works = alloc_percpu(struct work_struct); |
2918 | if (!works) |
2919 | return -ENOMEM; |
2920 | |
2921 | get_online_cpus(); |
2922 | |
2923 | for_each_online_cpu(cpu) { |
2924 | struct work_struct *work = per_cpu_ptr(works, cpu); |
2925 | |
2926 | INIT_WORK(work, func); |
2927 | schedule_work_on(cpu, work); |
2928 | } |
2929 | |
2930 | for_each_online_cpu(cpu) |
2931 | flush_work(per_cpu_ptr(works, cpu)); |
2932 | |
2933 | put_online_cpus(); |
2934 | free_percpu(works); |
2935 | return 0; |
2936 | } |
2937 | |
2938 | /** |
2939 | * flush_scheduled_work - ensure that any scheduled work has run to completion. |
2940 | * |
2941 | * Forces execution of the kernel-global workqueue and blocks until its |
2942 | * completion. |
2943 | * |
2944 | * Think twice before calling this function! It's very easy to get into |
2945 | * trouble if you don't take great care. Either of the following situations |
2946 | * will lead to deadlock: |
2947 | * |
2948 | * One of the work items currently on the workqueue needs to acquire |
2949 | * a lock held by your code or its caller. |
2950 | * |
2951 | * Your code is running in the context of a work routine. |
2952 | * |
2953 | * They will be detected by lockdep when they occur, but the first might not |
2954 | * occur very often. It depends on what work items are on the workqueue and |
2955 | * what locks they need, which you have no control over. |
2956 | * |
2957 | * In most situations flushing the entire workqueue is overkill; you merely |
2958 | * need to know that a particular work item isn't queued and isn't running. |
2959 | * In such cases you should use cancel_delayed_work_sync() or |
2960 | * cancel_work_sync() instead. |
2961 | */ |
2962 | void flush_scheduled_work(void) |
2963 | { |
2964 | flush_workqueue(system_wq); |
2965 | } |
2966 | EXPORT_SYMBOL(flush_scheduled_work); |
2967 | |
2968 | /** |
2969 | * execute_in_process_context - reliably execute the routine with user context |
2970 | * @fn: the function to execute |
2971 | * @ew: guaranteed storage for the execute work structure (must |
2972 | * be available when the work executes) |
2973 | * |
2974 | * Executes the function immediately if process context is available, |
2975 | * otherwise schedules the function for delayed execution. |
2976 | * |
2977 | * Return: 0 - function was executed |
2978 | * 1 - function was scheduled for execution |
2979 | */ |
2980 | int execute_in_process_context(work_func_t fn, struct execute_work *ew) |
2981 | { |
2982 | if (!in_interrupt()) { |
2983 | fn(&ew->work); |
2984 | return 0; |
2985 | } |
2986 | |
2987 | INIT_WORK(&ew->work, fn); |
2988 | schedule_work(&ew->work); |
2989 | |
2990 | return 1; |
2991 | } |
2992 | EXPORT_SYMBOL_GPL(execute_in_process_context); |
2993 | |
2994 | #ifdef CONFIG_SYSFS |
2995 | /* |
2996 | * Workqueues with WQ_SYSFS flag set is visible to userland via |
2997 | * /sys/bus/workqueue/devices/WQ_NAME. All visible workqueues have the |
2998 | * following attributes. |
2999 | * |
3000 | * per_cpu RO bool : whether the workqueue is per-cpu or unbound |
3001 | * max_active RW int : maximum number of in-flight work items |
3002 | * |
3003 | * Unbound workqueues have the following extra attributes. |
3004 | * |
3005 | * id RO int : the associated pool ID |
3006 | * nice RW int : nice value of the workers |
3007 | * cpumask RW mask : bitmask of allowed CPUs for the workers |
3008 | */ |
3009 | struct wq_device { |
3010 | struct workqueue_struct *wq; |
3011 | struct device dev; |
3012 | }; |
3013 | |
3014 | static struct workqueue_struct *dev_to_wq(struct device *dev) |
3015 | { |
3016 | struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); |
3017 | |
3018 | return wq_dev->wq; |
3019 | } |
3020 | |
3021 | static ssize_t per_cpu_show(struct device *dev, struct device_attribute *attr, |
3022 | char *buf) |
3023 | { |
3024 | struct workqueue_struct *wq = dev_to_wq(dev); |
3025 | |
3026 | return scnprintf(buf, PAGE_SIZE, "%d\n", (bool)!(wq->flags & WQ_UNBOUND)); |
3027 | } |
3028 | static DEVICE_ATTR_RO(per_cpu); |
3029 | |
3030 | static ssize_t max_active_show(struct device *dev, |
3031 | struct device_attribute *attr, char *buf) |
3032 | { |
3033 | struct workqueue_struct *wq = dev_to_wq(dev); |
3034 | |
3035 | return scnprintf(buf, PAGE_SIZE, "%d\n", wq->saved_max_active); |
3036 | } |
3037 | |
3038 | static ssize_t max_active_store(struct device *dev, |
3039 | struct device_attribute *attr, const char *buf, |
3040 | size_t count) |
3041 | { |
3042 | struct workqueue_struct *wq = dev_to_wq(dev); |
3043 | int val; |
3044 | |
3045 | if (sscanf(buf, "%d", &val) != 1 || val <= 0) |
3046 | return -EINVAL; |
3047 | |
3048 | workqueue_set_max_active(wq, val); |
3049 | return count; |
3050 | } |
3051 | static DEVICE_ATTR_RW(max_active); |
3052 | |
3053 | static struct attribute *wq_sysfs_attrs[] = { |
3054 | &dev_attr_per_cpu.attr, |
3055 | &dev_attr_max_active.attr, |
3056 | NULL, |
3057 | }; |
3058 | ATTRIBUTE_GROUPS(wq_sysfs); |
3059 | |
3060 | static ssize_t wq_pool_ids_show(struct device *dev, |
3061 | struct device_attribute *attr, char *buf) |
3062 | { |
3063 | struct workqueue_struct *wq = dev_to_wq(dev); |
3064 | const char *delim = ""; |
3065 | int node, written = 0; |
3066 | |
3067 | rcu_read_lock_sched(); |
3068 | for_each_node(node) { |
3069 | written += scnprintf(buf + written, PAGE_SIZE - written, |
3070 | "%s%d:%d", delim, node, |
3071 | unbound_pwq_by_node(wq, node)->pool->id); |
3072 | delim = " "; |
3073 | } |
3074 | written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); |
3075 | rcu_read_unlock_sched(); |
3076 | |
3077 | return written; |
3078 | } |
3079 | |
3080 | static ssize_t wq_nice_show(struct device *dev, struct device_attribute *attr, |
3081 | char *buf) |
3082 | { |
3083 | struct workqueue_struct *wq = dev_to_wq(dev); |
3084 | int written; |
3085 | |
3086 | mutex_lock(&wq->mutex); |
3087 | written = scnprintf(buf, PAGE_SIZE, "%d\n", wq->unbound_attrs->nice); |
3088 | mutex_unlock(&wq->mutex); |
3089 | |
3090 | return written; |
3091 | } |
3092 | |
3093 | /* prepare workqueue_attrs for sysfs store operations */ |
3094 | static struct workqueue_attrs *wq_sysfs_prep_attrs(struct workqueue_struct *wq) |
3095 | { |
3096 | struct workqueue_attrs *attrs; |
3097 | |
3098 | attrs = alloc_workqueue_attrs(GFP_KERNEL); |
3099 | if (!attrs) |
3100 | return NULL; |
3101 | |
3102 | mutex_lock(&wq->mutex); |
3103 | copy_workqueue_attrs(attrs, wq->unbound_attrs); |
3104 | mutex_unlock(&wq->mutex); |
3105 | return attrs; |
3106 | } |
3107 | |
3108 | static ssize_t wq_nice_store(struct device *dev, struct device_attribute *attr, |
3109 | const char *buf, size_t count) |
3110 | { |
3111 | struct workqueue_struct *wq = dev_to_wq(dev); |
3112 | struct workqueue_attrs *attrs; |
3113 | int ret; |
3114 | |
3115 | attrs = wq_sysfs_prep_attrs(wq); |
3116 | if (!attrs) |
3117 | return -ENOMEM; |
3118 | |
3119 | if (sscanf(buf, "%d", &attrs->nice) == 1 && |
3120 | attrs->nice >= MIN_NICE && attrs->nice <= MAX_NICE) |
3121 | ret = apply_workqueue_attrs(wq, attrs); |
3122 | else |
3123 | ret = -EINVAL; |
3124 | |
3125 | free_workqueue_attrs(attrs); |
3126 | return ret ?: count; |
3127 | } |
3128 | |
3129 | static ssize_t wq_cpumask_show(struct device *dev, |
3130 | struct device_attribute *attr, char *buf) |
3131 | { |
3132 | struct workqueue_struct *wq = dev_to_wq(dev); |
3133 | int written; |
3134 | |
3135 | mutex_lock(&wq->mutex); |
3136 | written = cpumask_scnprintf(buf, PAGE_SIZE, wq->unbound_attrs->cpumask); |
3137 | mutex_unlock(&wq->mutex); |
3138 | |
3139 | written += scnprintf(buf + written, PAGE_SIZE - written, "\n"); |
3140 | return written; |
3141 | } |
3142 | |
3143 | static ssize_t wq_cpumask_store(struct device *dev, |
3144 | struct device_attribute *attr, |
3145 | const char *buf, size_t count) |
3146 | { |
3147 | struct workqueue_struct *wq = dev_to_wq(dev); |
3148 | struct workqueue_attrs *attrs; |
3149 | int ret; |
3150 | |
3151 | attrs = wq_sysfs_prep_attrs(wq); |
3152 | if (!attrs) |
3153 | return -ENOMEM; |
3154 | |
3155 | ret = cpumask_parse(buf, attrs->cpumask); |
3156 | if (!ret) |
3157 | ret = apply_workqueue_attrs(wq, attrs); |
3158 | |
3159 | free_workqueue_attrs(attrs); |
3160 | return ret ?: count; |
3161 | } |
3162 | |
3163 | static ssize_t wq_numa_show(struct device *dev, struct device_attribute *attr, |
3164 | char *buf) |
3165 | { |
3166 | struct workqueue_struct *wq = dev_to_wq(dev); |
3167 | int written; |
3168 | |
3169 | mutex_lock(&wq->mutex); |
3170 | written = scnprintf(buf, PAGE_SIZE, "%d\n", |
3171 | !wq->unbound_attrs->no_numa); |
3172 | mutex_unlock(&wq->mutex); |
3173 | |
3174 | return written; |
3175 | } |
3176 | |
3177 | static ssize_t wq_numa_store(struct device *dev, struct device_attribute *attr, |
3178 | const char *buf, size_t count) |
3179 | { |
3180 | struct workqueue_struct *wq = dev_to_wq(dev); |
3181 | struct workqueue_attrs *attrs; |
3182 | int v, ret; |
3183 | |
3184 | attrs = wq_sysfs_prep_attrs(wq); |
3185 | if (!attrs) |
3186 | return -ENOMEM; |
3187 | |
3188 | ret = -EINVAL; |
3189 | if (sscanf(buf, "%d", &v) == 1) { |
3190 | attrs->no_numa = !v; |
3191 | ret = apply_workqueue_attrs(wq, attrs); |
3192 | } |
3193 | |
3194 | free_workqueue_attrs(attrs); |
3195 | return ret ?: count; |
3196 | } |
3197 | |
3198 | static struct device_attribute wq_sysfs_unbound_attrs[] = { |
3199 | __ATTR(pool_ids, 0444, wq_pool_ids_show, NULL), |
3200 | __ATTR(nice, 0644, wq_nice_show, wq_nice_store), |
3201 | __ATTR(cpumask, 0644, wq_cpumask_show, wq_cpumask_store), |
3202 | __ATTR(numa, 0644, wq_numa_show, wq_numa_store), |
3203 | __ATTR_NULL, |
3204 | }; |
3205 | |
3206 | static struct bus_type wq_subsys = { |
3207 | .name = "workqueue", |
3208 | .dev_groups = wq_sysfs_groups, |
3209 | }; |
3210 | |
3211 | static int __init wq_sysfs_init(void) |
3212 | { |
3213 | return subsys_virtual_register(&wq_subsys, NULL); |
3214 | } |
3215 | core_initcall(wq_sysfs_init); |
3216 | |
3217 | static void wq_device_release(struct device *dev) |
3218 | { |
3219 | struct wq_device *wq_dev = container_of(dev, struct wq_device, dev); |
3220 | |
3221 | kfree(wq_dev); |
3222 | } |
3223 | |
3224 | /** |
3225 | * workqueue_sysfs_register - make a workqueue visible in sysfs |
3226 | * @wq: the workqueue to register |
3227 | * |
3228 | * Expose @wq in sysfs under /sys/bus/workqueue/devices. |
3229 | * alloc_workqueue*() automatically calls this function if WQ_SYSFS is set |
3230 | * which is the preferred method. |
3231 | * |
3232 | * Workqueue user should use this function directly iff it wants to apply |
3233 | * workqueue_attrs before making the workqueue visible in sysfs; otherwise, |
3234 | * apply_workqueue_attrs() may race against userland updating the |
3235 | * attributes. |
3236 | * |
3237 | * Return: 0 on success, -errno on failure. |
3238 | */ |
3239 | int workqueue_sysfs_register(struct workqueue_struct *wq) |
3240 | { |
3241 | struct wq_device *wq_dev; |
3242 | int ret; |
3243 | |
3244 | /* |
3245 | * Adjusting max_active or creating new pwqs by applyting |
3246 | * attributes breaks ordering guarantee. Disallow exposing ordered |
3247 | * workqueues. |
3248 | */ |
3249 | if (WARN_ON(wq->flags & __WQ_ORDERED)) |
3250 | return -EINVAL; |
3251 | |
3252 | wq->wq_dev = wq_dev = kzalloc(sizeof(*wq_dev), GFP_KERNEL); |
3253 | if (!wq_dev) |
3254 | return -ENOMEM; |
3255 | |
3256 | wq_dev->wq = wq; |
3257 | wq_dev->dev.bus = &wq_subsys; |
3258 | wq_dev->dev.init_name = wq->name; |
3259 | wq_dev->dev.release = wq_device_release; |
3260 | |
3261 | /* |
3262 | * unbound_attrs are created separately. Suppress uevent until |
3263 | * everything is ready. |
3264 | */ |
3265 | dev_set_uevent_suppress(&wq_dev->dev, true); |
3266 | |
3267 | ret = device_register(&wq_dev->dev); |
3268 | if (ret) { |
3269 | kfree(wq_dev); |
3270 | wq->wq_dev = NULL; |
3271 | return ret; |
3272 | } |
3273 | |
3274 | if (wq->flags & WQ_UNBOUND) { |
3275 | struct device_attribute *attr; |
3276 | |
3277 | for (attr = wq_sysfs_unbound_attrs; attr->attr.name; attr++) { |
3278 | ret = device_create_file(&wq_dev->dev, attr); |
3279 | if (ret) { |
3280 | device_unregister(&wq_dev->dev); |
3281 | wq->wq_dev = NULL; |
3282 | return ret; |
3283 | } |
3284 | } |
3285 | } |
3286 | |
3287 | dev_set_uevent_suppress(&wq_dev->dev, false); |
3288 | kobject_uevent(&wq_dev->dev.kobj, KOBJ_ADD); |
3289 | return 0; |
3290 | } |
3291 | |
3292 | /** |
3293 | * workqueue_sysfs_unregister - undo workqueue_sysfs_register() |
3294 | * @wq: the workqueue to unregister |
3295 | * |
3296 | * If @wq is registered to sysfs by workqueue_sysfs_register(), unregister. |
3297 | */ |
3298 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq) |
3299 | { |
3300 | struct wq_device *wq_dev = wq->wq_dev; |
3301 | |
3302 | if (!wq->wq_dev) |
3303 | return; |
3304 | |
3305 | wq->wq_dev = NULL; |
3306 | device_unregister(&wq_dev->dev); |
3307 | } |
3308 | #else /* CONFIG_SYSFS */ |
3309 | static void workqueue_sysfs_unregister(struct workqueue_struct *wq) { } |
3310 | #endif /* CONFIG_SYSFS */ |
3311 | |
3312 | /** |
3313 | * free_workqueue_attrs - free a workqueue_attrs |
3314 | * @attrs: workqueue_attrs to free |
3315 | * |
3316 | * Undo alloc_workqueue_attrs(). |
3317 | */ |
3318 | void free_workqueue_attrs(struct workqueue_attrs *attrs) |
3319 | { |
3320 | if (attrs) { |
3321 | free_cpumask_var(attrs->cpumask); |
3322 | kfree(attrs); |
3323 | } |
3324 | } |
3325 | |
3326 | /** |
3327 | * alloc_workqueue_attrs - allocate a workqueue_attrs |
3328 | * @gfp_mask: allocation mask to use |
3329 | * |
3330 | * Allocate a new workqueue_attrs, initialize with default settings and |
3331 | * return it. |
3332 | * |
3333 | * Return: The allocated new workqueue_attr on success. %NULL on failure. |
3334 | */ |
3335 | struct workqueue_attrs *alloc_workqueue_attrs(gfp_t gfp_mask) |
3336 | { |
3337 | struct workqueue_attrs *attrs; |
3338 | |
3339 | attrs = kzalloc(sizeof(*attrs), gfp_mask); |
3340 | if (!attrs) |
3341 | goto fail; |
3342 | if (!alloc_cpumask_var(&attrs->cpumask, gfp_mask)) |
3343 | goto fail; |
3344 | |
3345 | cpumask_copy(attrs->cpumask, cpu_possible_mask); |
3346 | return attrs; |
3347 | fail: |
3348 | free_workqueue_attrs(attrs); |
3349 | return NULL; |
3350 | } |
3351 | |
3352 | static void copy_workqueue_attrs(struct workqueue_attrs *to, |
3353 | const struct workqueue_attrs *from) |
3354 | { |
3355 | to->nice = from->nice; |
3356 | cpumask_copy(to->cpumask, from->cpumask); |
3357 | /* |
3358 | * Unlike hash and equality test, this function doesn't ignore |
3359 | * ->no_numa as it is used for both pool and wq attrs. Instead, |
3360 | * get_unbound_pool() explicitly clears ->no_numa after copying. |
3361 | */ |
3362 | to->no_numa = from->no_numa; |
3363 | } |
3364 | |
3365 | /* hash value of the content of @attr */ |
3366 | static u32 wqattrs_hash(const struct workqueue_attrs *attrs) |
3367 | { |
3368 | u32 hash = 0; |
3369 | |
3370 | hash = jhash_1word(attrs->nice, hash); |
3371 | hash = jhash(cpumask_bits(attrs->cpumask), |
3372 | BITS_TO_LONGS(nr_cpumask_bits) * sizeof(long), hash); |
3373 | return hash; |
3374 | } |
3375 | |
3376 | /* content equality test */ |
3377 | static bool wqattrs_equal(const struct workqueue_attrs *a, |
3378 | const struct workqueue_attrs *b) |
3379 | { |
3380 | if (a->nice != b->nice) |
3381 | return false; |
3382 | if (!cpumask_equal(a->cpumask, b->cpumask)) |
3383 | return false; |
3384 | return true; |
3385 | } |
3386 | |
3387 | /** |
3388 | * init_worker_pool - initialize a newly zalloc'd worker_pool |
3389 | * @pool: worker_pool to initialize |
3390 | * |
3391 | * Initiailize a newly zalloc'd @pool. It also allocates @pool->attrs. |
3392 | * |
3393 | * Return: 0 on success, -errno on failure. Even on failure, all fields |
3394 | * inside @pool proper are initialized and put_unbound_pool() can be called |
3395 | * on @pool safely to release it. |
3396 | */ |
3397 | static int init_worker_pool(struct worker_pool *pool) |
3398 | { |
3399 | spin_lock_init(&pool->lock); |
3400 | pool->id = -1; |
3401 | pool->cpu = -1; |
3402 | pool->node = NUMA_NO_NODE; |
3403 | pool->flags |= POOL_DISASSOCIATED; |
3404 | INIT_LIST_HEAD(&pool->worklist); |
3405 | INIT_LIST_HEAD(&pool->idle_list); |
3406 | hash_init(pool->busy_hash); |
3407 | |
3408 | init_timer_deferrable(&pool->idle_timer); |
3409 | pool->idle_timer.function = idle_worker_timeout; |
3410 | pool->idle_timer.data = (unsigned long)pool; |
3411 | |
3412 | setup_timer(&pool->mayday_timer, pool_mayday_timeout, |
3413 | (unsigned long)pool); |
3414 | |
3415 | mutex_init(&pool->manager_arb); |
3416 | mutex_init(&pool->attach_mutex); |
3417 | INIT_LIST_HEAD(&pool->workers); |
3418 | |
3419 | ida_init(&pool->worker_ida); |
3420 | INIT_HLIST_NODE(&pool->hash_node); |
3421 | pool->refcnt = 1; |
3422 | |
3423 | /* shouldn't fail above this point */ |
3424 | pool->attrs = alloc_workqueue_attrs(GFP_KERNEL); |
3425 | if (!pool->attrs) |
3426 | return -ENOMEM; |
3427 | return 0; |
3428 | } |
3429 | |
3430 | static void rcu_free_pool(struct rcu_head *rcu) |
3431 | { |
3432 | struct worker_pool *pool = container_of(rcu, struct worker_pool, rcu); |
3433 | |
3434 | ida_destroy(&pool->worker_ida); |
3435 | free_workqueue_attrs(pool->attrs); |
3436 | kfree(pool); |
3437 | } |
3438 | |
3439 | /** |
3440 | * put_unbound_pool - put a worker_pool |
3441 | * @pool: worker_pool to put |
3442 | * |
3443 | * Put @pool. If its refcnt reaches zero, it gets destroyed in sched-RCU |
3444 | * safe manner. get_unbound_pool() calls this function on its failure path |
3445 | * and this function should be able to release pools which went through, |
3446 | * successfully or not, init_worker_pool(). |
3447 | * |
3448 | * Should be called with wq_pool_mutex held. |
3449 | */ |
3450 | static void put_unbound_pool(struct worker_pool *pool) |
3451 | { |
3452 | DECLARE_COMPLETION_ONSTACK(detach_completion); |
3453 | struct worker *worker; |
3454 | |
3455 | lockdep_assert_held(&wq_pool_mutex); |
3456 | |
3457 | if (--pool->refcnt) |
3458 | return; |
3459 | |
3460 | /* sanity checks */ |
3461 | if (WARN_ON(!(pool->flags & POOL_DISASSOCIATED)) || |
3462 | WARN_ON(!list_empty(&pool->worklist))) |
3463 | return; |
3464 | |
3465 | /* release id and unhash */ |
3466 | if (pool->id >= 0) |
3467 | idr_remove(&worker_pool_idr, pool->id); |
3468 | hash_del(&pool->hash_node); |
3469 | |
3470 | /* |
3471 | * Become the manager and destroy all workers. Grabbing |
3472 | * manager_arb prevents @pool's workers from blocking on |
3473 | * attach_mutex. |
3474 | */ |
3475 | mutex_lock(&pool->manager_arb); |
3476 | |
3477 | spin_lock_irq(&pool->lock); |
3478 | while ((worker = first_idle_worker(pool))) |
3479 | destroy_worker(worker); |
3480 | WARN_ON(pool->nr_workers || pool->nr_idle); |
3481 | spin_unlock_irq(&pool->lock); |
3482 | |
3483 | mutex_lock(&pool->attach_mutex); |
3484 | if (!list_empty(&pool->workers)) |
3485 | pool->detach_completion = &detach_completion; |
3486 | mutex_unlock(&pool->attach_mutex); |
3487 | |
3488 | if (pool->detach_completion) |
3489 | wait_for_completion(pool->detach_completion); |
3490 | |
3491 | mutex_unlock(&pool->manager_arb); |
3492 | |
3493 | /* shut down the timers */ |
3494 | del_timer_sync(&pool->idle_timer); |
3495 | del_timer_sync(&pool->mayday_timer); |
3496 | |
3497 | /* sched-RCU protected to allow dereferences from get_work_pool() */ |
3498 | call_rcu_sched(&pool->rcu, rcu_free_pool); |
3499 | } |
3500 | |
3501 | /** |
3502 | * get_unbound_pool - get a worker_pool with the specified attributes |
3503 | * @attrs: the attributes of the worker_pool to get |
3504 | * |
3505 | * Obtain a worker_pool which has the same attributes as @attrs, bump the |
3506 | * reference count and return it. If there already is a matching |
3507 | * worker_pool, it will be used; otherwise, this function attempts to |
3508 | * create a new one. |
3509 | * |
3510 | * Should be called with wq_pool_mutex held. |
3511 | * |
3512 | * Return: On success, a worker_pool with the same attributes as @attrs. |
3513 | * On failure, %NULL. |
3514 | */ |
3515 | static struct worker_pool *get_unbound_pool(const struct workqueue_attrs *attrs) |
3516 | { |
3517 | u32 hash = wqattrs_hash(attrs); |
3518 | struct worker_pool *pool; |
3519 | int node; |
3520 | |
3521 | lockdep_assert_held(&wq_pool_mutex); |
3522 | |
3523 | /* do we already have a matching pool? */ |
3524 | hash_for_each_possible(unbound_pool_hash, pool, hash_node, hash) { |
3525 | if (wqattrs_equal(pool->attrs, attrs)) { |
3526 | pool->refcnt++; |
3527 | goto out_unlock; |
3528 | } |
3529 | } |
3530 | |
3531 | /* nope, create a new one */ |
3532 | pool = kzalloc(sizeof(*pool), GFP_KERNEL); |
3533 | if (!pool || init_worker_pool(pool) < 0) |
3534 | goto fail; |
3535 | |
3536 | lockdep_set_subclass(&pool->lock, 1); /* see put_pwq() */ |
3537 | copy_workqueue_attrs(pool->attrs, attrs); |
3538 | |
3539 | /* |
3540 | * no_numa isn't a worker_pool attribute, always clear it. See |
3541 | * 'struct workqueue_attrs' comments for detail. |
3542 | */ |
3543 | pool->attrs->no_numa = false; |
3544 | |
3545 | /* if cpumask is contained inside a NUMA node, we belong to that node */ |
3546 | if (wq_numa_enabled) { |
3547 | for_each_node(node) { |
3548 | if (cpumask_subset(pool->attrs->cpumask, |
3549 | wq_numa_possible_cpumask[node])) { |
3550 | pool->node = node; |
3551 | break; |
3552 | } |
3553 | } |
3554 | } |
3555 | |
3556 | if (worker_pool_assign_id(pool) < 0) |
3557 | goto fail; |
3558 | |
3559 | /* create and start the initial worker */ |
3560 | if (create_and_start_worker(pool) < 0) |
3561 | goto fail; |
3562 | |
3563 | /* install */ |
3564 | hash_add(unbound_pool_hash, &pool->hash_node, hash); |
3565 | out_unlock: |
3566 | return pool; |
3567 | fail: |
3568 | if (pool) |
3569 | put_unbound_pool(pool); |
3570 | return NULL; |
3571 | } |
3572 | |
3573 | static void rcu_free_pwq(struct rcu_head *rcu) |
3574 | { |
3575 | kmem_cache_free(pwq_cache, |
3576 | container_of(rcu, struct pool_workqueue, rcu)); |
3577 | } |
3578 | |
3579 | /* |
3580 | * Scheduled on system_wq by put_pwq() when an unbound pwq hits zero refcnt |
3581 | * and needs to be destroyed. |
3582 | */ |
3583 | static void pwq_unbound_release_workfn(struct work_struct *work) |
3584 | { |
3585 | struct pool_workqueue *pwq = container_of(work, struct pool_workqueue, |
3586 | unbound_release_work); |
3587 | struct workqueue_struct *wq = pwq->wq; |
3588 | struct worker_pool *pool = pwq->pool; |
3589 | bool is_last; |
3590 | |
3591 | if (WARN_ON_ONCE(!(wq->flags & WQ_UNBOUND))) |
3592 | return; |
3593 | |
3594 | /* |
3595 | * Unlink @pwq. Synchronization against wq->mutex isn't strictly |
3596 | * necessary on release but do it anyway. It's easier to verify |
3597 | * and consistent with the linking path. |
3598 | */ |
3599 | mutex_lock(&wq->mutex); |
3600 | list_del_rcu(&pwq->pwqs_node); |
3601 | is_last = list_empty(&wq->pwqs); |
3602 | mutex_unlock(&wq->mutex); |
3603 | |
3604 | mutex_lock(&wq_pool_mutex); |
3605 | put_unbound_pool(pool); |
3606 | mutex_unlock(&wq_pool_mutex); |
3607 | |
3608 | call_rcu_sched(&pwq->rcu, rcu_free_pwq); |
3609 | |
3610 | /* |
3611 | * If we're the last pwq going away, @wq is already dead and no one |
3612 | * is gonna access it anymore. Free it. |
3613 | */ |
3614 | if (is_last) { |
3615 | free_workqueue_attrs(wq->unbound_attrs); |
3616 | kfree(wq); |
3617 | } |
3618 | } |
3619 | |
3620 | /** |
3621 | * pwq_adjust_max_active - update a pwq's max_active to the current setting |
3622 | * @pwq: target pool_workqueue |
3623 | * |
3624 | * If @pwq isn't freezing, set @pwq->max_active to the associated |
3625 | * workqueue's saved_max_active and activate delayed work items |
3626 | * accordingly. If @pwq is freezing, clear @pwq->max_active to zero. |
3627 | */ |
3628 | static void pwq_adjust_max_active(struct pool_workqueue *pwq) |
3629 | { |
3630 | struct workqueue_struct *wq = pwq->wq; |
3631 | bool freezable = wq->flags & WQ_FREEZABLE; |
3632 | |
3633 | /* for @wq->saved_max_active */ |
3634 | lockdep_assert_held(&wq->mutex); |
3635 | |
3636 | /* fast exit for non-freezable wqs */ |
3637 | if (!freezable && pwq->max_active == wq->saved_max_active) |
3638 | return; |
3639 | |
3640 | spin_lock_irq(&pwq->pool->lock); |
3641 | |
3642 | /* |
3643 | * During [un]freezing, the caller is responsible for ensuring that |
3644 | * this function is called at least once after @workqueue_freezing |
3645 | * is updated and visible. |
3646 | */ |
3647 | if (!freezable || !workqueue_freezing) { |
3648 | pwq->max_active = wq->saved_max_active; |
3649 | |
3650 | while (!list_empty(&pwq->delayed_works) && |
3651 | pwq->nr_active < pwq->max_active) |
3652 | pwq_activate_first_delayed(pwq); |
3653 | |
3654 | /* |
3655 | * Need to kick a worker after thawed or an unbound wq's |
3656 | * max_active is bumped. It's a slow path. Do it always. |
3657 | */ |
3658 | wake_up_worker(pwq->pool); |
3659 | } else { |
3660 | pwq->max_active = 0; |
3661 | } |
3662 | |
3663 | spin_unlock_irq(&pwq->pool->lock); |
3664 | } |
3665 | |
3666 | /* initialize newly alloced @pwq which is associated with @wq and @pool */ |
3667 | static void init_pwq(struct pool_workqueue *pwq, struct workqueue_struct *wq, |
3668 | struct worker_pool *pool) |
3669 | { |
3670 | BUG_ON((unsigned long)pwq & WORK_STRUCT_FLAG_MASK); |
3671 | |
3672 | memset(pwq, 0, sizeof(*pwq)); |
3673 | |
3674 | pwq->pool = pool; |
3675 | pwq->wq = wq; |
3676 | pwq->flush_color = -1; |
3677 | pwq->refcnt = 1; |
3678 | INIT_LIST_HEAD(&pwq->delayed_works); |
3679 | INIT_LIST_HEAD(&pwq->pwqs_node); |
3680 | INIT_LIST_HEAD(&pwq->mayday_node); |
3681 | INIT_WORK(&pwq->unbound_release_work, pwq_unbound_release_workfn); |
3682 | } |
3683 | |
3684 | /* sync @pwq with the current state of its associated wq and link it */ |
3685 | static void link_pwq(struct pool_workqueue *pwq) |
3686 | { |
3687 | struct workqueue_struct *wq = pwq->wq; |
3688 | |
3689 | lockdep_assert_held(&wq->mutex); |
3690 | |
3691 | /* may be called multiple times, ignore if already linked */ |
3692 | if (!list_empty(&pwq->pwqs_node)) |
3693 | return; |
3694 | |
3695 | /* |
3696 | * Set the matching work_color. This is synchronized with |
3697 | * wq->mutex to avoid confusing flush_workqueue(). |
3698 | */ |
3699 | pwq->work_color = wq->work_color; |
3700 | |
3701 | /* sync max_active to the current setting */ |
3702 | pwq_adjust_max_active(pwq); |
3703 | |
3704 | /* link in @pwq */ |
3705 | list_add_rcu(&pwq->pwqs_node, &wq->pwqs); |
3706 | } |
3707 | |
3708 | /* obtain a pool matching @attr and create a pwq associating the pool and @wq */ |
3709 | static struct pool_workqueue *alloc_unbound_pwq(struct workqueue_struct *wq, |
3710 | const struct workqueue_attrs *attrs) |
3711 | { |
3712 | struct worker_pool *pool; |
3713 | struct pool_workqueue *pwq; |
3714 | |
3715 | lockdep_assert_held(&wq_pool_mutex); |
3716 | |
3717 | pool = get_unbound_pool(attrs); |
3718 | if (!pool) |
3719 | return NULL; |
3720 | |
3721 | pwq = kmem_cache_alloc_node(pwq_cache, GFP_KERNEL, pool->node); |
3722 | if (!pwq) { |
3723 | put_unbound_pool(pool); |
3724 | return NULL; |
3725 | } |
3726 | |
3727 | init_pwq(pwq, wq, pool); |
3728 | return pwq; |
3729 | } |
3730 | |
3731 | /* undo alloc_unbound_pwq(), used only in the error path */ |
3732 | static void free_unbound_pwq(struct pool_workqueue *pwq) |
3733 | { |
3734 | lockdep_assert_held(&wq_pool_mutex); |
3735 | |
3736 | if (pwq) { |
3737 | put_unbound_pool(pwq->pool); |
3738 | kmem_cache_free(pwq_cache, pwq); |
3739 | } |
3740 | } |
3741 | |
3742 | /** |
3743 | * wq_calc_node_mask - calculate a wq_attrs' cpumask for the specified node |
3744 | * @attrs: the wq_attrs of interest |
3745 | * @node: the target NUMA node |
3746 | * @cpu_going_down: if >= 0, the CPU to consider as offline |
3747 | * @cpumask: outarg, the resulting cpumask |
3748 | * |
3749 | * Calculate the cpumask a workqueue with @attrs should use on @node. If |
3750 | * @cpu_going_down is >= 0, that cpu is considered offline during |
3751 | * calculation. The result is stored in @cpumask. |
3752 | * |
3753 | * If NUMA affinity is not enabled, @attrs->cpumask is always used. If |
3754 | * enabled and @node has online CPUs requested by @attrs, the returned |
3755 | * cpumask is the intersection of the possible CPUs of @node and |
3756 | * @attrs->cpumask. |
3757 | * |
3758 | * The caller is responsible for ensuring that the cpumask of @node stays |
3759 | * stable. |
3760 | * |
3761 | * Return: %true if the resulting @cpumask is different from @attrs->cpumask, |
3762 | * %false if equal. |
3763 | */ |
3764 | static bool wq_calc_node_cpumask(const struct workqueue_attrs *attrs, int node, |
3765 | int cpu_going_down, cpumask_t *cpumask) |
3766 | { |
3767 | if (!wq_numa_enabled || attrs->no_numa) |
3768 | goto use_dfl; |
3769 | |
3770 | /* does @node have any online CPUs @attrs wants? */ |
3771 | cpumask_and(cpumask, cpumask_of_node(node), attrs->cpumask); |
3772 | if (cpu_going_down >= 0) |
3773 | cpumask_clear_cpu(cpu_going_down, cpumask); |
3774 | |
3775 | if (cpumask_empty(cpumask)) |
3776 | goto use_dfl; |
3777 | |
3778 | /* yeap, return possible CPUs in @node that @attrs wants */ |
3779 | cpumask_and(cpumask, attrs->cpumask, wq_numa_possible_cpumask[node]); |
3780 | return !cpumask_equal(cpumask, attrs->cpumask); |
3781 | |
3782 | use_dfl: |
3783 | cpumask_copy(cpumask, attrs->cpumask); |
3784 | return false; |
3785 | } |
3786 | |
3787 | /* install @pwq into @wq's numa_pwq_tbl[] for @node and return the old pwq */ |
3788 | static struct pool_workqueue *numa_pwq_tbl_install(struct workqueue_struct *wq, |
3789 | int node, |
3790 | struct pool_workqueue *pwq) |
3791 | { |
3792 | struct pool_workqueue *old_pwq; |
3793 | |
3794 | lockdep_assert_held(&wq->mutex); |
3795 | |
3796 | /* link_pwq() can handle duplicate calls */ |
3797 | link_pwq(pwq); |
3798 | |
3799 | old_pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); |
3800 | rcu_assign_pointer(wq->numa_pwq_tbl[node], pwq); |
3801 | return old_pwq; |
3802 | } |
3803 | |
3804 | /** |
3805 | * apply_workqueue_attrs - apply new workqueue_attrs to an unbound workqueue |
3806 | * @wq: the target workqueue |
3807 | * @attrs: the workqueue_attrs to apply, allocated with alloc_workqueue_attrs() |
3808 | * |
3809 | * Apply @attrs to an unbound workqueue @wq. Unless disabled, on NUMA |
3810 | * machines, this function maps a separate pwq to each NUMA node with |
3811 | * possibles CPUs in @attrs->cpumask so that work items are affine to the |
3812 | * NUMA node it was issued on. Older pwqs are released as in-flight work |
3813 | * items finish. Note that a work item which repeatedly requeues itself |
3814 | * back-to-back will stay on its current pwq. |
3815 | * |
3816 | * Performs GFP_KERNEL allocations. |
3817 | * |
3818 | * Return: 0 on success and -errno on failure. |
3819 | */ |
3820 | int apply_workqueue_attrs(struct workqueue_struct *wq, |
3821 | const struct workqueue_attrs *attrs) |
3822 | { |
3823 | struct workqueue_attrs *new_attrs, *tmp_attrs; |
3824 | struct pool_workqueue **pwq_tbl, *dfl_pwq; |
3825 | int node, ret; |
3826 | |
3827 | /* only unbound workqueues can change attributes */ |
3828 | if (WARN_ON(!(wq->flags & WQ_UNBOUND))) |
3829 | return -EINVAL; |
3830 | |
3831 | /* creating multiple pwqs breaks ordering guarantee */ |
3832 | if (WARN_ON((wq->flags & __WQ_ORDERED) && !list_empty(&wq->pwqs))) |
3833 | return -EINVAL; |
3834 | |
3835 | pwq_tbl = kzalloc(wq_numa_tbl_len * sizeof(pwq_tbl[0]), GFP_KERNEL); |
3836 | new_attrs = alloc_workqueue_attrs(GFP_KERNEL); |
3837 | tmp_attrs = alloc_workqueue_attrs(GFP_KERNEL); |
3838 | if (!pwq_tbl || !new_attrs || !tmp_attrs) |
3839 | goto enomem; |
3840 | |
3841 | /* make a copy of @attrs and sanitize it */ |
3842 | copy_workqueue_attrs(new_attrs, attrs); |
3843 | cpumask_and(new_attrs->cpumask, new_attrs->cpumask, cpu_possible_mask); |
3844 | |
3845 | /* |
3846 | * We may create multiple pwqs with differing cpumasks. Make a |
3847 | * copy of @new_attrs which will be modified and used to obtain |
3848 | * pools. |
3849 | */ |
3850 | copy_workqueue_attrs(tmp_attrs, new_attrs); |
3851 | |
3852 | /* |
3853 | * CPUs should stay stable across pwq creations and installations. |
3854 | * Pin CPUs, determine the target cpumask for each node and create |
3855 | * pwqs accordingly. |
3856 | */ |
3857 | get_online_cpus(); |
3858 | |
3859 | mutex_lock(&wq_pool_mutex); |
3860 | |
3861 | /* |
3862 | * If something goes wrong during CPU up/down, we'll fall back to |
3863 | * the default pwq covering whole @attrs->cpumask. Always create |
3864 | * it even if we don't use it immediately. |
3865 | */ |
3866 | dfl_pwq = alloc_unbound_pwq(wq, new_attrs); |
3867 | if (!dfl_pwq) |
3868 | goto enomem_pwq; |
3869 | |
3870 | for_each_node(node) { |
3871 | if (wq_calc_node_cpumask(attrs, node, -1, tmp_attrs->cpumask)) { |
3872 | pwq_tbl[node] = alloc_unbound_pwq(wq, tmp_attrs); |
3873 | if (!pwq_tbl[node]) |
3874 | goto enomem_pwq; |
3875 | } else { |
3876 | dfl_pwq->refcnt++; |
3877 | pwq_tbl[node] = dfl_pwq; |
3878 | } |
3879 | } |
3880 | |
3881 | mutex_unlock(&wq_pool_mutex); |
3882 | |
3883 | /* all pwqs have been created successfully, let's install'em */ |
3884 | mutex_lock(&wq->mutex); |
3885 | |
3886 | copy_workqueue_attrs(wq->unbound_attrs, new_attrs); |
3887 | |
3888 | /* save the previous pwq and install the new one */ |
3889 | for_each_node(node) |
3890 | pwq_tbl[node] = numa_pwq_tbl_install(wq, node, pwq_tbl[node]); |
3891 | |
3892 | /* @dfl_pwq might not have been used, ensure it's linked */ |
3893 | link_pwq(dfl_pwq); |
3894 | swap(wq->dfl_pwq, dfl_pwq); |
3895 | |
3896 | mutex_unlock(&wq->mutex); |
3897 | |
3898 | /* put the old pwqs */ |
3899 | for_each_node(node) |
3900 | put_pwq_unlocked(pwq_tbl[node]); |
3901 | put_pwq_unlocked(dfl_pwq); |
3902 | |
3903 | put_online_cpus(); |
3904 | ret = 0; |
3905 | /* fall through */ |
3906 | out_free: |
3907 | free_workqueue_attrs(tmp_attrs); |
3908 | free_workqueue_attrs(new_attrs); |
3909 | kfree(pwq_tbl); |
3910 | return ret; |
3911 | |
3912 | enomem_pwq: |
3913 | free_unbound_pwq(dfl_pwq); |
3914 | for_each_node(node) |
3915 | if (pwq_tbl && pwq_tbl[node] != dfl_pwq) |
3916 | free_unbound_pwq(pwq_tbl[node]); |
3917 | mutex_unlock(&wq_pool_mutex); |
3918 | put_online_cpus(); |
3919 | enomem: |
3920 | ret = -ENOMEM; |
3921 | goto out_free; |
3922 | } |
3923 | |
3924 | /** |
3925 | * wq_update_unbound_numa - update NUMA affinity of a wq for CPU hot[un]plug |
3926 | * @wq: the target workqueue |
3927 | * @cpu: the CPU coming up or going down |
3928 | * @online: whether @cpu is coming up or going down |
3929 | * |
3930 | * This function is to be called from %CPU_DOWN_PREPARE, %CPU_ONLINE and |
3931 | * %CPU_DOWN_FAILED. @cpu is being hot[un]plugged, update NUMA affinity of |
3932 | * @wq accordingly. |
3933 | * |
3934 | * If NUMA affinity can't be adjusted due to memory allocation failure, it |
3935 | * falls back to @wq->dfl_pwq which may not be optimal but is always |
3936 | * correct. |
3937 | * |
3938 | * Note that when the last allowed CPU of a NUMA node goes offline for a |
3939 | * workqueue with a cpumask spanning multiple nodes, the workers which were |
3940 | * already executing the work items for the workqueue will lose their CPU |
3941 | * affinity and may execute on any CPU. This is similar to how per-cpu |
3942 | * workqueues behave on CPU_DOWN. If a workqueue user wants strict |
3943 | * affinity, it's the user's responsibility to flush the work item from |
3944 | * CPU_DOWN_PREPARE. |
3945 | */ |
3946 | static void wq_update_unbound_numa(struct workqueue_struct *wq, int cpu, |
3947 | bool online) |
3948 | { |
3949 | int node = cpu_to_node(cpu); |
3950 | int cpu_off = online ? -1 : cpu; |
3951 | struct pool_workqueue *old_pwq = NULL, *pwq; |
3952 | struct workqueue_attrs *target_attrs; |
3953 | cpumask_t *cpumask; |
3954 | |
3955 | lockdep_assert_held(&wq_pool_mutex); |
3956 | |
3957 | if (!wq_numa_enabled || !(wq->flags & WQ_UNBOUND)) |
3958 | return; |
3959 | |
3960 | /* |
3961 | * We don't wanna alloc/free wq_attrs for each wq for each CPU. |
3962 | * Let's use a preallocated one. The following buf is protected by |
3963 | * CPU hotplug exclusion. |
3964 | */ |
3965 | target_attrs = wq_update_unbound_numa_attrs_buf; |
3966 | cpumask = target_attrs->cpumask; |
3967 | |
3968 | mutex_lock(&wq->mutex); |
3969 | if (wq->unbound_attrs->no_numa) |
3970 | goto out_unlock; |
3971 | |
3972 | copy_workqueue_attrs(target_attrs, wq->unbound_attrs); |
3973 | pwq = unbound_pwq_by_node(wq, node); |
3974 | |
3975 | /* |
3976 | * Let's determine what needs to be done. If the target cpumask is |
3977 | * different from wq's, we need to compare it to @pwq's and create |
3978 | * a new one if they don't match. If the target cpumask equals |
3979 | * wq's, the default pwq should be used. |
3980 | */ |
3981 | if (wq_calc_node_cpumask(wq->unbound_attrs, node, cpu_off, cpumask)) { |
3982 | if (cpumask_equal(cpumask, pwq->pool->attrs->cpumask)) |
3983 | goto out_unlock; |
3984 | } else { |
3985 | goto use_dfl_pwq; |
3986 | } |
3987 | |
3988 | mutex_unlock(&wq->mutex); |
3989 | |
3990 | /* create a new pwq */ |
3991 | pwq = alloc_unbound_pwq(wq, target_attrs); |
3992 | if (!pwq) { |
3993 | pr_warn("workqueue: allocation failed while updating NUMA affinity of \"%s\"\n", |
3994 | wq->name); |
3995 | mutex_lock(&wq->mutex); |
3996 | goto use_dfl_pwq; |
3997 | } |
3998 | |
3999 | /* |
4000 | * Install the new pwq. As this function is called only from CPU |
4001 | * hotplug callbacks and applying a new attrs is wrapped with |
4002 | * get/put_online_cpus(), @wq->unbound_attrs couldn't have changed |
4003 | * inbetween. |
4004 | */ |
4005 | mutex_lock(&wq->mutex); |
4006 | old_pwq = numa_pwq_tbl_install(wq, node, pwq); |
4007 | goto out_unlock; |
4008 | |
4009 | use_dfl_pwq: |
4010 | spin_lock_irq(&wq->dfl_pwq->pool->lock); |
4011 | get_pwq(wq->dfl_pwq); |
4012 | spin_unlock_irq(&wq->dfl_pwq->pool->lock); |
4013 | old_pwq = numa_pwq_tbl_install(wq, node, wq->dfl_pwq); |
4014 | out_unlock: |
4015 | mutex_unlock(&wq->mutex); |
4016 | put_pwq_unlocked(old_pwq); |
4017 | } |
4018 | |
4019 | static int alloc_and_link_pwqs(struct workqueue_struct *wq) |
4020 | { |
4021 | bool highpri = wq->flags & WQ_HIGHPRI; |
4022 | int cpu, ret; |
4023 | |
4024 | if (!(wq->flags & WQ_UNBOUND)) { |
4025 | wq->cpu_pwqs = alloc_percpu(struct pool_workqueue); |
4026 | if (!wq->cpu_pwqs) |
4027 | return -ENOMEM; |
4028 | |
4029 | for_each_possible_cpu(cpu) { |
4030 | struct pool_workqueue *pwq = |
4031 | per_cpu_ptr(wq->cpu_pwqs, cpu); |
4032 | struct worker_pool *cpu_pools = |
4033 | per_cpu(cpu_worker_pools, cpu); |
4034 | |
4035 | init_pwq(pwq, wq, &cpu_pools[highpri]); |
4036 | |
4037 | mutex_lock(&wq->mutex); |
4038 | link_pwq(pwq); |
4039 | mutex_unlock(&wq->mutex); |
4040 | } |
4041 | return 0; |
4042 | } else if (wq->flags & __WQ_ORDERED) { |
4043 | ret = apply_workqueue_attrs(wq, ordered_wq_attrs[highpri]); |
4044 | /* there should only be single pwq for ordering guarantee */ |
4045 | WARN(!ret && (wq->pwqs.next != &wq->dfl_pwq->pwqs_node || |
4046 | wq->pwqs.prev != &wq->dfl_pwq->pwqs_node), |
4047 | "ordering guarantee broken for workqueue %s\n", wq->name); |
4048 | return ret; |
4049 | } else { |
4050 | return apply_workqueue_attrs(wq, unbound_std_wq_attrs[highpri]); |
4051 | } |
4052 | } |
4053 | |
4054 | static int wq_clamp_max_active(int max_active, unsigned int flags, |
4055 | const char *name) |
4056 | { |
4057 | int lim = flags & WQ_UNBOUND ? WQ_UNBOUND_MAX_ACTIVE : WQ_MAX_ACTIVE; |
4058 | |
4059 | if (max_active < 1 || max_active > lim) |
4060 | pr_warn("workqueue: max_active %d requested for %s is out of range, clamping between %d and %d\n", |
4061 | max_active, name, 1, lim); |
4062 | |
4063 | return clamp_val(max_active, 1, lim); |
4064 | } |
4065 | |
4066 | struct workqueue_struct *__alloc_workqueue_key(const char *fmt, |
4067 | unsigned int flags, |
4068 | int max_active, |
4069 | struct lock_class_key *key, |
4070 | const char *lock_name, ...) |
4071 | { |
4072 | size_t tbl_size = 0; |
4073 | va_list args; |
4074 | struct workqueue_struct *wq; |
4075 | struct pool_workqueue *pwq; |
4076 | |
4077 | /* see the comment above the definition of WQ_POWER_EFFICIENT */ |
4078 | if ((flags & WQ_POWER_EFFICIENT) && wq_power_efficient) |
4079 | flags |= WQ_UNBOUND; |
4080 | |
4081 | /* allocate wq and format name */ |
4082 | if (flags & WQ_UNBOUND) |
4083 | tbl_size = wq_numa_tbl_len * sizeof(wq->numa_pwq_tbl[0]); |
4084 | |
4085 | wq = kzalloc(sizeof(*wq) + tbl_size, GFP_KERNEL); |
4086 | if (!wq) |
4087 | return NULL; |
4088 | |
4089 | if (flags & WQ_UNBOUND) { |
4090 | wq->unbound_attrs = alloc_workqueue_attrs(GFP_KERNEL); |
4091 | if (!wq->unbound_attrs) |
4092 | goto err_free_wq; |
4093 | } |
4094 | |
4095 | va_start(args, lock_name); |
4096 | vsnprintf(wq->name, sizeof(wq->name), fmt, args); |
4097 | va_end(args); |
4098 | |
4099 | max_active = max_active ?: WQ_DFL_ACTIVE; |
4100 | max_active = wq_clamp_max_active(max_active, flags, wq->name); |
4101 | |
4102 | /* init wq */ |
4103 | wq->flags = flags; |
4104 | wq->saved_max_active = max_active; |
4105 | mutex_init(&wq->mutex); |
4106 | atomic_set(&wq->nr_pwqs_to_flush, 0); |
4107 | INIT_LIST_HEAD(&wq->pwqs); |
4108 | INIT_LIST_HEAD(&wq->flusher_queue); |
4109 | INIT_LIST_HEAD(&wq->flusher_overflow); |
4110 | INIT_LIST_HEAD(&wq->maydays); |
4111 | |
4112 | lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); |
4113 | INIT_LIST_HEAD(&wq->list); |
4114 | |
4115 | if (alloc_and_link_pwqs(wq) < 0) |
4116 | goto err_free_wq; |
4117 | |
4118 | /* |
4119 | * Workqueues which may be used during memory reclaim should |
4120 | * have a rescuer to guarantee forward progress. |
4121 | */ |
4122 | if (flags & WQ_MEM_RECLAIM) { |
4123 | struct worker *rescuer; |
4124 | |
4125 | rescuer = alloc_worker(); |
4126 | if (!rescuer) |
4127 | goto err_destroy; |
4128 | |
4129 | rescuer->rescue_wq = wq; |
4130 | rescuer->task = kthread_create(rescuer_thread, rescuer, "%s", |
4131 | wq->name); |
4132 | if (IS_ERR(rescuer->task)) { |
4133 | kfree(rescuer); |
4134 | goto err_destroy; |
4135 | } |
4136 | |
4137 | wq->rescuer = rescuer; |
4138 | rescuer->task->flags |= PF_NO_SETAFFINITY; |
4139 | wake_up_process(rescuer->task); |
4140 | } |
4141 | |
4142 | if ((wq->flags & WQ_SYSFS) && workqueue_sysfs_register(wq)) |
4143 | goto err_destroy; |
4144 | |
4145 | /* |
4146 | * wq_pool_mutex protects global freeze state and workqueues list. |
4147 | * Grab it, adjust max_active and add the new @wq to workqueues |
4148 | * list. |
4149 | */ |
4150 | mutex_lock(&wq_pool_mutex); |
4151 | |
4152 | mutex_lock(&wq->mutex); |
4153 | for_each_pwq(pwq, wq) |
4154 | pwq_adjust_max_active(pwq); |
4155 | mutex_unlock(&wq->mutex); |
4156 | |
4157 | list_add(&wq->list, &workqueues); |
4158 | |
4159 | mutex_unlock(&wq_pool_mutex); |
4160 | |
4161 | return wq; |
4162 | |
4163 | err_free_wq: |
4164 | free_workqueue_attrs(wq->unbound_attrs); |
4165 | kfree(wq); |
4166 | return NULL; |
4167 | err_destroy: |
4168 | destroy_workqueue(wq); |
4169 | return NULL; |
4170 | } |
4171 | EXPORT_SYMBOL_GPL(__alloc_workqueue_key); |
4172 | |
4173 | /** |
4174 | * destroy_workqueue - safely terminate a workqueue |
4175 | * @wq: target workqueue |
4176 | * |
4177 | * Safely destroy a workqueue. All work currently pending will be done first. |
4178 | */ |
4179 | void destroy_workqueue(struct workqueue_struct *wq) |
4180 | { |
4181 | struct pool_workqueue *pwq; |
4182 | int node; |
4183 | |
4184 | /* drain it before proceeding with destruction */ |
4185 | drain_workqueue(wq); |
4186 | |
4187 | /* sanity checks */ |
4188 | mutex_lock(&wq->mutex); |
4189 | for_each_pwq(pwq, wq) { |
4190 | int i; |
4191 | |
4192 | for (i = 0; i < WORK_NR_COLORS; i++) { |
4193 | if (WARN_ON(pwq->nr_in_flight[i])) { |
4194 | mutex_unlock(&wq->mutex); |
4195 | return; |
4196 | } |
4197 | } |
4198 | |
4199 | if (WARN_ON((pwq != wq->dfl_pwq) && (pwq->refcnt > 1)) || |
4200 | WARN_ON(pwq->nr_active) || |
4201 | WARN_ON(!list_empty(&pwq->delayed_works))) { |
4202 | mutex_unlock(&wq->mutex); |
4203 | return; |
4204 | } |
4205 | } |
4206 | mutex_unlock(&wq->mutex); |
4207 | |
4208 | /* |
4209 | * wq list is used to freeze wq, remove from list after |
4210 | * flushing is complete in case freeze races us. |
4211 | */ |
4212 | mutex_lock(&wq_pool_mutex); |
4213 | list_del_init(&wq->list); |
4214 | mutex_unlock(&wq_pool_mutex); |
4215 | |
4216 | workqueue_sysfs_unregister(wq); |
4217 | |
4218 | if (wq->rescuer) { |
4219 | kthread_stop(wq->rescuer->task); |
4220 | kfree(wq->rescuer); |
4221 | wq->rescuer = NULL; |
4222 | } |
4223 | |
4224 | if (!(wq->flags & WQ_UNBOUND)) { |
4225 | /* |
4226 | * The base ref is never dropped on per-cpu pwqs. Directly |
4227 | * free the pwqs and wq. |
4228 | */ |
4229 | free_percpu(wq->cpu_pwqs); |
4230 | kfree(wq); |
4231 | } else { |
4232 | /* |
4233 | * We're the sole accessor of @wq at this point. Directly |
4234 | * access numa_pwq_tbl[] and dfl_pwq to put the base refs. |
4235 | * @wq will be freed when the last pwq is released. |
4236 | */ |
4237 | for_each_node(node) { |
4238 | pwq = rcu_access_pointer(wq->numa_pwq_tbl[node]); |
4239 | RCU_INIT_POINTER(wq->numa_pwq_tbl[node], NULL); |
4240 | put_pwq_unlocked(pwq); |
4241 | } |
4242 | |
4243 | /* |
4244 | * Put dfl_pwq. @wq may be freed any time after dfl_pwq is |
4245 | * put. Don't access it afterwards. |
4246 | */ |
4247 | pwq = wq->dfl_pwq; |
4248 | wq->dfl_pwq = NULL; |
4249 | put_pwq_unlocked(pwq); |
4250 | } |
4251 | } |
4252 | EXPORT_SYMBOL_GPL(destroy_workqueue); |
4253 | |
4254 | /** |
4255 | * workqueue_set_max_active - adjust max_active of a workqueue |
4256 | * @wq: target workqueue |
4257 | * @max_active: new max_active value. |
4258 | * |
4259 | * Set max_active of @wq to @max_active. |
4260 | * |
4261 | * CONTEXT: |
4262 | * Don't call from IRQ context. |
4263 | */ |
4264 | void workqueue_set_max_active(struct workqueue_struct *wq, int max_active) |
4265 | { |
4266 | struct pool_workqueue *pwq; |
4267 | |
4268 | /* disallow meddling with max_active for ordered workqueues */ |
4269 | if (WARN_ON(wq->flags & __WQ_ORDERED)) |
4270 | return; |
4271 | |
4272 | max_active = wq_clamp_max_active(max_active, wq->flags, wq->name); |
4273 | |
4274 | mutex_lock(&wq->mutex); |
4275 | |
4276 | wq->saved_max_active = max_active; |
4277 | |
4278 | for_each_pwq(pwq, wq) |
4279 | pwq_adjust_max_active(pwq); |
4280 | |
4281 | mutex_unlock(&wq->mutex); |
4282 | } |
4283 | EXPORT_SYMBOL_GPL(workqueue_set_max_active); |
4284 | |
4285 | /** |
4286 | * current_is_workqueue_rescuer - is %current workqueue rescuer? |
4287 | * |
4288 | * Determine whether %current is a workqueue rescuer. Can be used from |
4289 | * work functions to determine whether it's being run off the rescuer task. |
4290 | * |
4291 | * Return: %true if %current is a workqueue rescuer. %false otherwise. |
4292 | */ |
4293 | bool current_is_workqueue_rescuer(void) |
4294 | { |
4295 | struct worker *worker = current_wq_worker(); |
4296 | |
4297 | return worker && worker->rescue_wq; |
4298 | } |
4299 | |
4300 | /** |
4301 | * workqueue_congested - test whether a workqueue is congested |
4302 | * @cpu: CPU in question |
4303 | * @wq: target workqueue |
4304 | * |
4305 | * Test whether @wq's cpu workqueue for @cpu is congested. There is |
4306 | * no synchronization around this function and the test result is |
4307 | * unreliable and only useful as advisory hints or for debugging. |
4308 | * |
4309 | * If @cpu is WORK_CPU_UNBOUND, the test is performed on the local CPU. |
4310 | * Note that both per-cpu and unbound workqueues may be associated with |
4311 | * multiple pool_workqueues which have separate congested states. A |
4312 | * workqueue being congested on one CPU doesn't mean the workqueue is also |
4313 | * contested on other CPUs / NUMA nodes. |
4314 | * |
4315 | * Return: |
4316 | * %true if congested, %false otherwise. |
4317 | */ |
4318 | bool workqueue_congested(int cpu, struct workqueue_struct *wq) |
4319 | { |
4320 | struct pool_workqueue *pwq; |
4321 | bool ret; |
4322 | |
4323 | rcu_read_lock_sched(); |
4324 | |
4325 | if (cpu == WORK_CPU_UNBOUND) |
4326 | cpu = smp_processor_id(); |
4327 | |
4328 | if (!(wq->flags & WQ_UNBOUND)) |
4329 | pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); |
4330 | else |
4331 | pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); |
4332 | |
4333 | ret = !list_empty(&pwq->delayed_works); |
4334 | rcu_read_unlock_sched(); |
4335 | |
4336 | return ret; |
4337 | } |
4338 | EXPORT_SYMBOL_GPL(workqueue_congested); |
4339 | |
4340 | /** |
4341 | * work_busy - test whether a work is currently pending or running |
4342 | * @work: the work to be tested |
4343 | * |
4344 | * Test whether @work is currently pending or running. There is no |
4345 | * synchronization around this function and the test result is |
4346 | * unreliable and only useful as advisory hints or for debugging. |
4347 | * |
4348 | * Return: |
4349 | * OR'd bitmask of WORK_BUSY_* bits. |
4350 | */ |
4351 | unsigned int work_busy(struct work_struct *work) |
4352 | { |
4353 | struct worker_pool *pool; |
4354 | unsigned long flags; |
4355 | unsigned int ret = 0; |
4356 | |
4357 | if (work_pending(work)) |
4358 | ret |= WORK_BUSY_PENDING; |
4359 | |
4360 | local_irq_save(flags); |
4361 | pool = get_work_pool(work); |
4362 | if (pool) { |
4363 | spin_lock(&pool->lock); |
4364 | if (find_worker_executing_work(pool, work)) |
4365 | ret |= WORK_BUSY_RUNNING; |
4366 | spin_unlock(&pool->lock); |
4367 | } |
4368 | local_irq_restore(flags); |
4369 | |
4370 | return ret; |
4371 | } |
4372 | EXPORT_SYMBOL_GPL(work_busy); |
4373 | |
4374 | /** |
4375 | * set_worker_desc - set description for the current work item |
4376 | * @fmt: printf-style format string |
4377 | * @...: arguments for the format string |
4378 | * |
4379 | * This function can be called by a running work function to describe what |
4380 | * the work item is about. If the worker task gets dumped, this |
4381 | * information will be printed out together to help debugging. The |
4382 | * description can be at most WORKER_DESC_LEN including the trailing '\0'. |
4383 | */ |
4384 | void set_worker_desc(const char *fmt, ...) |
4385 | { |
4386 | struct worker *worker = current_wq_worker(); |
4387 | va_list args; |
4388 | |
4389 | if (worker) { |
4390 | va_start(args, fmt); |
4391 | vsnprintf(worker->desc, sizeof(worker->desc), fmt, args); |
4392 | va_end(args); |
4393 | worker->desc_valid = true; |
4394 | } |
4395 | } |
4396 | |
4397 | /** |
4398 | * print_worker_info - print out worker information and description |
4399 | * @log_lvl: the log level to use when printing |
4400 | * @task: target task |
4401 | * |
4402 | * If @task is a worker and currently executing a work item, print out the |
4403 | * name of the workqueue being serviced and worker description set with |
4404 | * set_worker_desc() by the currently executing work item. |
4405 | * |
4406 | * This function can be safely called on any task as long as the |
4407 | * task_struct itself is accessible. While safe, this function isn't |
4408 | * synchronized and may print out mixups or garbages of limited length. |
4409 | */ |
4410 | void print_worker_info(const char *log_lvl, struct task_struct *task) |
4411 | { |
4412 | work_func_t *fn = NULL; |
4413 | char name[WQ_NAME_LEN] = { }; |
4414 | char desc[WORKER_DESC_LEN] = { }; |
4415 | struct pool_workqueue *pwq = NULL; |
4416 | struct workqueue_struct *wq = NULL; |
4417 | bool desc_valid = false; |
4418 | struct worker *worker; |
4419 | |
4420 | if (!(task->flags & PF_WQ_WORKER)) |
4421 | return; |
4422 | |
4423 | /* |
4424 | * This function is called without any synchronization and @task |
4425 | * could be in any state. Be careful with dereferences. |
4426 | */ |
4427 | worker = probe_kthread_data(task); |
4428 | |
4429 | /* |
4430 | * Carefully copy the associated workqueue's workfn and name. Keep |
4431 | * the original last '\0' in case the original contains garbage. |
4432 | */ |
4433 | probe_kernel_read(&fn, &worker->current_func, sizeof(fn)); |
4434 | probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq)); |
4435 | probe_kernel_read(&wq, &pwq->wq, sizeof(wq)); |
4436 | probe_kernel_read(name, wq->name, sizeof(name) - 1); |
4437 | |
4438 | /* copy worker description */ |
4439 | probe_kernel_read(&desc_valid, &worker->desc_valid, sizeof(desc_valid)); |
4440 | if (desc_valid) |
4441 | probe_kernel_read(desc, worker->desc, sizeof(desc) - 1); |
4442 | |
4443 | if (fn || name[0] || desc[0]) { |
4444 | printk("%sWorkqueue: %s %pf", log_lvl, name, fn); |
4445 | if (desc[0]) |
4446 | pr_cont(" (%s)", desc); |
4447 | pr_cont("\n"); |
4448 | } |
4449 | } |
4450 | |
4451 | /* |
4452 | * CPU hotplug. |
4453 | * |
4454 | * There are two challenges in supporting CPU hotplug. Firstly, there |
4455 | * are a lot of assumptions on strong associations among work, pwq and |
4456 | * pool which make migrating pending and scheduled works very |
4457 | * difficult to implement without impacting hot paths. Secondly, |
4458 | * worker pools serve mix of short, long and very long running works making |
4459 | * blocked draining impractical. |
4460 | * |
4461 | * This is solved by allowing the pools to be disassociated from the CPU |
4462 | * running as an unbound one and allowing it to be reattached later if the |
4463 | * cpu comes back online. |
4464 | */ |
4465 | |
4466 | static void wq_unbind_fn(struct work_struct *work) |
4467 | { |
4468 | int cpu = smp_processor_id(); |
4469 | struct worker_pool *pool; |
4470 | struct worker *worker; |
4471 | |
4472 | for_each_cpu_worker_pool(pool, cpu) { |
4473 | WARN_ON_ONCE(cpu != smp_processor_id()); |
4474 | |
4475 | mutex_lock(&pool->attach_mutex); |
4476 | spin_lock_irq(&pool->lock); |
4477 | |
4478 | /* |
4479 | * We've blocked all attach/detach operations. Make all workers |
4480 | * unbound and set DISASSOCIATED. Before this, all workers |
4481 | * except for the ones which are still executing works from |
4482 | * before the last CPU down must be on the cpu. After |
4483 | * this, they may become diasporas. |
4484 | */ |
4485 | for_each_pool_worker(worker, pool) |
4486 | worker->flags |= WORKER_UNBOUND; |
4487 | |
4488 | pool->flags |= POOL_DISASSOCIATED; |
4489 | |
4490 | spin_unlock_irq(&pool->lock); |
4491 | mutex_unlock(&pool->attach_mutex); |
4492 | |
4493 | /* |
4494 | * Call schedule() so that we cross rq->lock and thus can |
4495 | * guarantee sched callbacks see the %WORKER_UNBOUND flag. |
4496 | * This is necessary as scheduler callbacks may be invoked |
4497 | * from other cpus. |
4498 | */ |
4499 | schedule(); |
4500 | |
4501 | /* |
4502 | * Sched callbacks are disabled now. Zap nr_running. |
4503 | * After this, nr_running stays zero and need_more_worker() |
4504 | * and keep_working() are always true as long as the |
4505 | * worklist is not empty. This pool now behaves as an |
4506 | * unbound (in terms of concurrency management) pool which |
4507 | * are served by workers tied to the pool. |
4508 | */ |
4509 | atomic_set(&pool->nr_running, 0); |
4510 | |
4511 | /* |
4512 | * With concurrency management just turned off, a busy |
4513 | * worker blocking could lead to lengthy stalls. Kick off |
4514 | * unbound chain execution of currently pending work items. |
4515 | */ |
4516 | spin_lock_irq(&pool->lock); |
4517 | wake_up_worker(pool); |
4518 | spin_unlock_irq(&pool->lock); |
4519 | } |
4520 | } |
4521 | |
4522 | /** |
4523 | * rebind_workers - rebind all workers of a pool to the associated CPU |
4524 | * @pool: pool of interest |
4525 | * |
4526 | * @pool->cpu is coming online. Rebind all workers to the CPU. |
4527 | */ |
4528 | static void rebind_workers(struct worker_pool *pool) |
4529 | { |
4530 | struct worker *worker; |
4531 | |
4532 | lockdep_assert_held(&pool->attach_mutex); |
4533 | |
4534 | /* |
4535 | * Restore CPU affinity of all workers. As all idle workers should |
4536 | * be on the run-queue of the associated CPU before any local |
4537 | * wake-ups for concurrency management happen, restore CPU affinty |
4538 | * of all workers first and then clear UNBOUND. As we're called |
4539 | * from CPU_ONLINE, the following shouldn't fail. |
4540 | */ |
4541 | for_each_pool_worker(worker, pool) |
4542 | WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, |
4543 | pool->attrs->cpumask) < 0); |
4544 | |
4545 | spin_lock_irq(&pool->lock); |
4546 | |
4547 | for_each_pool_worker(worker, pool) { |
4548 | unsigned int worker_flags = worker->flags; |
4549 | |
4550 | /* |
4551 | * A bound idle worker should actually be on the runqueue |
4552 | * of the associated CPU for local wake-ups targeting it to |
4553 | * work. Kick all idle workers so that they migrate to the |
4554 | * associated CPU. Doing this in the same loop as |
4555 | * replacing UNBOUND with REBOUND is safe as no worker will |
4556 | * be bound before @pool->lock is released. |
4557 | */ |
4558 | if (worker_flags & WORKER_IDLE) |
4559 | wake_up_process(worker->task); |
4560 | |
4561 | /* |
4562 | * We want to clear UNBOUND but can't directly call |
4563 | * worker_clr_flags() or adjust nr_running. Atomically |
4564 | * replace UNBOUND with another NOT_RUNNING flag REBOUND. |
4565 | * @worker will clear REBOUND using worker_clr_flags() when |
4566 | * it initiates the next execution cycle thus restoring |
4567 | * concurrency management. Note that when or whether |
4568 | * @worker clears REBOUND doesn't affect correctness. |
4569 | * |
4570 | * ACCESS_ONCE() is necessary because @worker->flags may be |
4571 | * tested without holding any lock in |
4572 | * wq_worker_waking_up(). Without it, NOT_RUNNING test may |
4573 | * fail incorrectly leading to premature concurrency |
4574 | * management operations. |
4575 | */ |
4576 | WARN_ON_ONCE(!(worker_flags & WORKER_UNBOUND)); |
4577 | worker_flags |= WORKER_REBOUND; |
4578 | worker_flags &= ~WORKER_UNBOUND; |
4579 | ACCESS_ONCE(worker->flags) = worker_flags; |
4580 | } |
4581 | |
4582 | spin_unlock_irq(&pool->lock); |
4583 | } |
4584 | |
4585 | /** |
4586 | * restore_unbound_workers_cpumask - restore cpumask of unbound workers |
4587 | * @pool: unbound pool of interest |
4588 | * @cpu: the CPU which is coming up |
4589 | * |
4590 | * An unbound pool may end up with a cpumask which doesn't have any online |
4591 | * CPUs. When a worker of such pool get scheduled, the scheduler resets |
4592 | * its cpus_allowed. If @cpu is in @pool's cpumask which didn't have any |
4593 | * online CPU before, cpus_allowed of all its workers should be restored. |
4594 | */ |
4595 | static void restore_unbound_workers_cpumask(struct worker_pool *pool, int cpu) |
4596 | { |
4597 | static cpumask_t cpumask; |
4598 | struct worker *worker; |
4599 | |
4600 | lockdep_assert_held(&pool->attach_mutex); |
4601 | |
4602 | /* is @cpu allowed for @pool? */ |
4603 | if (!cpumask_test_cpu(cpu, pool->attrs->cpumask)) |
4604 | return; |
4605 | |
4606 | /* is @cpu the only online CPU? */ |
4607 | cpumask_and(&cpumask, pool->attrs->cpumask, cpu_online_mask); |
4608 | if (cpumask_weight(&cpumask) != 1) |
4609 | return; |
4610 | |
4611 | /* as we're called from CPU_ONLINE, the following shouldn't fail */ |
4612 | for_each_pool_worker(worker, pool) |
4613 | WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task, |
4614 | pool->attrs->cpumask) < 0); |
4615 | } |
4616 | |
4617 | /* |
4618 | * Workqueues should be brought up before normal priority CPU notifiers. |
4619 | * This will be registered high priority CPU notifier. |
4620 | */ |
4621 | static int workqueue_cpu_up_callback(struct notifier_block *nfb, |
4622 | unsigned long action, |
4623 | void *hcpu) |
4624 | { |
4625 | int cpu = (unsigned long)hcpu; |
4626 | struct worker_pool *pool; |
4627 | struct workqueue_struct *wq; |
4628 | int pi; |
4629 | |
4630 | switch (action & ~CPU_TASKS_FROZEN) { |
4631 | case CPU_UP_PREPARE: |
4632 | for_each_cpu_worker_pool(pool, cpu) { |
4633 | if (pool->nr_workers) |
4634 | continue; |
4635 | if (create_and_start_worker(pool) < 0) |
4636 | return NOTIFY_BAD; |
4637 | } |
4638 | break; |
4639 | |
4640 | case CPU_DOWN_FAILED: |
4641 | case CPU_ONLINE: |
4642 | mutex_lock(&wq_pool_mutex); |
4643 | |
4644 | for_each_pool(pool, pi) { |
4645 | mutex_lock(&pool->attach_mutex); |
4646 | |
4647 | if (pool->cpu == cpu) { |
4648 | spin_lock_irq(&pool->lock); |
4649 | pool->flags &= ~POOL_DISASSOCIATED; |
4650 | spin_unlock_irq(&pool->lock); |
4651 | |
4652 | rebind_workers(pool); |
4653 | } else if (pool->cpu < 0) { |
4654 | restore_unbound_workers_cpumask(pool, cpu); |
4655 | } |
4656 | |
4657 | mutex_unlock(&pool->attach_mutex); |
4658 | } |
4659 | |
4660 | /* update NUMA affinity of unbound workqueues */ |
4661 | list_for_each_entry(wq, &workqueues, list) |
4662 | wq_update_unbound_numa(wq, cpu, true); |
4663 | |
4664 | mutex_unlock(&wq_pool_mutex); |
4665 | break; |
4666 | } |
4667 | return NOTIFY_OK; |
4668 | } |
4669 | |
4670 | /* |
4671 | * Workqueues should be brought down after normal priority CPU notifiers. |
4672 | * This will be registered as low priority CPU notifier. |
4673 | */ |
4674 | static int workqueue_cpu_down_callback(struct notifier_block *nfb, |
4675 | unsigned long action, |
4676 | void *hcpu) |
4677 | { |
4678 | int cpu = (unsigned long)hcpu; |
4679 | struct work_struct unbind_work; |
4680 | struct workqueue_struct *wq; |
4681 | |
4682 | switch (action & ~CPU_TASKS_FROZEN) { |
4683 | case CPU_DOWN_PREPARE: |
4684 | /* unbinding per-cpu workers should happen on the local CPU */ |
4685 | INIT_WORK_ONSTACK(&unbind_work, wq_unbind_fn); |
4686 | queue_work_on(cpu, system_highpri_wq, &unbind_work); |
4687 | |
4688 | /* update NUMA affinity of unbound workqueues */ |
4689 | mutex_lock(&wq_pool_mutex); |
4690 | list_for_each_entry(wq, &workqueues, list) |
4691 | wq_update_unbound_numa(wq, cpu, false); |
4692 | mutex_unlock(&wq_pool_mutex); |
4693 | |
4694 | /* wait for per-cpu unbinding to finish */ |
4695 | flush_work(&unbind_work); |
4696 | destroy_work_on_stack(&unbind_work); |
4697 | break; |
4698 | } |
4699 | return NOTIFY_OK; |
4700 | } |
4701 | |
4702 | #ifdef CONFIG_SMP |
4703 | |
4704 | struct work_for_cpu { |
4705 | struct work_struct work; |
4706 | long (*fn)(void *); |
4707 | void *arg; |
4708 | long ret; |
4709 | }; |
4710 | |
4711 | static void work_for_cpu_fn(struct work_struct *work) |
4712 | { |
4713 | struct work_for_cpu *wfc = container_of(work, struct work_for_cpu, work); |
4714 | |
4715 | wfc->ret = wfc->fn(wfc->arg); |
4716 | } |
4717 | |
4718 | /** |
4719 | * work_on_cpu - run a function in user context on a particular cpu |
4720 | * @cpu: the cpu to run on |
4721 | * @fn: the function to run |
4722 | * @arg: the function arg |
4723 | * |
4724 | * It is up to the caller to ensure that the cpu doesn't go offline. |
4725 | * The caller must not hold any locks which would prevent @fn from completing. |
4726 | * |
4727 | * Return: The value @fn returns. |
4728 | */ |
4729 | long work_on_cpu(int cpu, long (*fn)(void *), void *arg) |
4730 | { |
4731 | struct work_for_cpu wfc = { .fn = fn, .arg = arg }; |
4732 | |
4733 | INIT_WORK_ONSTACK(&wfc.work, work_for_cpu_fn); |
4734 | schedule_work_on(cpu, &wfc.work); |
4735 | flush_work(&wfc.work); |
4736 | destroy_work_on_stack(&wfc.work); |
4737 | return wfc.ret; |
4738 | } |
4739 | EXPORT_SYMBOL_GPL(work_on_cpu); |
4740 | #endif /* CONFIG_SMP */ |
4741 | |
4742 | #ifdef CONFIG_FREEZER |
4743 | |
4744 | /** |
4745 | * freeze_workqueues_begin - begin freezing workqueues |
4746 | * |
4747 | * Start freezing workqueues. After this function returns, all freezable |
4748 | * workqueues will queue new works to their delayed_works list instead of |
4749 | * pool->worklist. |
4750 | * |
4751 | * CONTEXT: |
4752 | * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. |
4753 | */ |
4754 | void freeze_workqueues_begin(void) |
4755 | { |
4756 | struct workqueue_struct *wq; |
4757 | struct pool_workqueue *pwq; |
4758 | |
4759 | mutex_lock(&wq_pool_mutex); |
4760 | |
4761 | WARN_ON_ONCE(workqueue_freezing); |
4762 | workqueue_freezing = true; |
4763 | |
4764 | list_for_each_entry(wq, &workqueues, list) { |
4765 | mutex_lock(&wq->mutex); |
4766 | for_each_pwq(pwq, wq) |
4767 | pwq_adjust_max_active(pwq); |
4768 | mutex_unlock(&wq->mutex); |
4769 | } |
4770 | |
4771 | mutex_unlock(&wq_pool_mutex); |
4772 | } |
4773 | |
4774 | /** |
4775 | * freeze_workqueues_busy - are freezable workqueues still busy? |
4776 | * |
4777 | * Check whether freezing is complete. This function must be called |
4778 | * between freeze_workqueues_begin() and thaw_workqueues(). |
4779 | * |
4780 | * CONTEXT: |
4781 | * Grabs and releases wq_pool_mutex. |
4782 | * |
4783 | * Return: |
4784 | * %true if some freezable workqueues are still busy. %false if freezing |
4785 | * is complete. |
4786 | */ |
4787 | bool freeze_workqueues_busy(void) |
4788 | { |
4789 | bool busy = false; |
4790 | struct workqueue_struct *wq; |
4791 | struct pool_workqueue *pwq; |
4792 | |
4793 | mutex_lock(&wq_pool_mutex); |
4794 | |
4795 | WARN_ON_ONCE(!workqueue_freezing); |
4796 | |
4797 | list_for_each_entry(wq, &workqueues, list) { |
4798 | if (!(wq->flags & WQ_FREEZABLE)) |
4799 | continue; |
4800 | /* |
4801 | * nr_active is monotonically decreasing. It's safe |
4802 | * to peek without lock. |
4803 | */ |
4804 | rcu_read_lock_sched(); |
4805 | for_each_pwq(pwq, wq) { |
4806 | WARN_ON_ONCE(pwq->nr_active < 0); |
4807 | if (pwq->nr_active) { |
4808 | busy = true; |
4809 | rcu_read_unlock_sched(); |
4810 | goto out_unlock; |
4811 | } |
4812 | } |
4813 | rcu_read_unlock_sched(); |
4814 | } |
4815 | out_unlock: |
4816 | mutex_unlock(&wq_pool_mutex); |
4817 | return busy; |
4818 | } |
4819 | |
4820 | /** |
4821 | * thaw_workqueues - thaw workqueues |
4822 | * |
4823 | * Thaw workqueues. Normal queueing is restored and all collected |
4824 | * frozen works are transferred to their respective pool worklists. |
4825 | * |
4826 | * CONTEXT: |
4827 | * Grabs and releases wq_pool_mutex, wq->mutex and pool->lock's. |
4828 | */ |
4829 | void thaw_workqueues(void) |
4830 | { |
4831 | struct workqueue_struct *wq; |
4832 | struct pool_workqueue *pwq; |
4833 | |
4834 | mutex_lock(&wq_pool_mutex); |
4835 | |
4836 | if (!workqueue_freezing) |
4837 | goto out_unlock; |
4838 | |
4839 | workqueue_freezing = false; |
4840 | |
4841 | /* restore max_active and repopulate worklist */ |
4842 | list_for_each_entry(wq, &workqueues, list) { |
4843 | mutex_lock(&wq->mutex); |
4844 | for_each_pwq(pwq, wq) |
4845 | pwq_adjust_max_active(pwq); |
4846 | mutex_unlock(&wq->mutex); |
4847 | } |
4848 | |
4849 | out_unlock: |
4850 | mutex_unlock(&wq_pool_mutex); |
4851 | } |
4852 | #endif /* CONFIG_FREEZER */ |
4853 | |
4854 | static void __init wq_numa_init(void) |
4855 | { |
4856 | cpumask_var_t *tbl; |
4857 | int node, cpu; |
4858 | |
4859 | /* determine NUMA pwq table len - highest node id + 1 */ |
4860 | for_each_node(node) |
4861 | wq_numa_tbl_len = max(wq_numa_tbl_len, node + 1); |
4862 | |
4863 | if (num_possible_nodes() <= 1) |
4864 | return; |
4865 | |
4866 | if (wq_disable_numa) { |
4867 | pr_info("workqueue: NUMA affinity support disabled\n"); |
4868 | return; |
4869 | } |
4870 | |
4871 | wq_update_unbound_numa_attrs_buf = alloc_workqueue_attrs(GFP_KERNEL); |
4872 | BUG_ON(!wq_update_unbound_numa_attrs_buf); |
4873 | |
4874 | /* |
4875 | * We want masks of possible CPUs of each node which isn't readily |
4876 | * available. Build one from cpu_to_node() which should have been |
4877 | * fully initialized by now. |
4878 | */ |
4879 | tbl = kzalloc(wq_numa_tbl_len * sizeof(tbl[0]), GFP_KERNEL); |
4880 | BUG_ON(!tbl); |
4881 | |
4882 | for_each_node(node) |
4883 | BUG_ON(!zalloc_cpumask_var_node(&tbl[node], GFP_KERNEL, |
4884 | node_online(node) ? node : NUMA_NO_NODE)); |
4885 | |
4886 | for_each_possible_cpu(cpu) { |
4887 | node = cpu_to_node(cpu); |
4888 | if (WARN_ON(node == NUMA_NO_NODE)) { |
4889 | pr_warn("workqueue: NUMA node mapping not available for cpu%d, disabling NUMA support\n", cpu); |
4890 | /* happens iff arch is bonkers, let's just proceed */ |
4891 | return; |
4892 | } |
4893 | cpumask_set_cpu(cpu, tbl[node]); |
4894 | } |
4895 | |
4896 | wq_numa_possible_cpumask = tbl; |
4897 | wq_numa_enabled = true; |
4898 | } |
4899 | |
4900 | static int __init init_workqueues(void) |
4901 | { |
4902 | int std_nice[NR_STD_WORKER_POOLS] = { 0, HIGHPRI_NICE_LEVEL }; |
4903 | int i, cpu; |
4904 | |
4905 | WARN_ON(__alignof__(struct pool_workqueue) < __alignof__(long long)); |
4906 | |
4907 | pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); |
4908 | |
4909 | cpu_notifier(workqueue_cpu_up_callback, CPU_PRI_WORKQUEUE_UP); |
4910 | hotcpu_notifier(workqueue_cpu_down_callback, CPU_PRI_WORKQUEUE_DOWN); |
4911 | |
4912 | wq_numa_init(); |
4913 | |
4914 | /* initialize CPU pools */ |
4915 | for_each_possible_cpu(cpu) { |
4916 | struct worker_pool *pool; |
4917 | |
4918 | i = 0; |
4919 | for_each_cpu_worker_pool(pool, cpu) { |
4920 | BUG_ON(init_worker_pool(pool)); |
4921 | pool->cpu = cpu; |
4922 | cpumask_copy(pool->attrs->cpumask, cpumask_of(cpu)); |
4923 | pool->attrs->nice = std_nice[i++]; |
4924 | pool->node = cpu_to_node(cpu); |
4925 | |
4926 | /* alloc pool ID */ |
4927 | mutex_lock(&wq_pool_mutex); |
4928 | BUG_ON(worker_pool_assign_id(pool)); |
4929 | mutex_unlock(&wq_pool_mutex); |
4930 | } |
4931 | } |
4932 | |
4933 | /* create the initial worker */ |
4934 | for_each_online_cpu(cpu) { |
4935 | struct worker_pool *pool; |
4936 | |
4937 | for_each_cpu_worker_pool(pool, cpu) { |
4938 | pool->flags &= ~POOL_DISASSOCIATED; |
4939 | BUG_ON(create_and_start_worker(pool) < 0); |
4940 | } |
4941 | } |
4942 | |
4943 | /* create default unbound and ordered wq attrs */ |
4944 | for (i = 0; i < NR_STD_WORKER_POOLS; i++) { |
4945 | struct workqueue_attrs *attrs; |
4946 | |
4947 | BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL))); |
4948 | attrs->nice = std_nice[i]; |
4949 | unbound_std_wq_attrs[i] = attrs; |
4950 | |
4951 | /* |
4952 | * An ordered wq should have only one pwq as ordering is |
4953 | * guaranteed by max_active which is enforced by pwqs. |
4954 | * Turn off NUMA so that dfl_pwq is used for all nodes. |
4955 | */ |
4956 | BUG_ON(!(attrs = alloc_workqueue_attrs(GFP_KERNEL))); |
4957 | attrs->nice = std_nice[i]; |
4958 | attrs->no_numa = true; |
4959 | ordered_wq_attrs[i] = attrs; |
4960 | } |
4961 | |
4962 | system_wq = alloc_workqueue("events", 0, 0); |
4963 | system_highpri_wq = alloc_workqueue("events_highpri", WQ_HIGHPRI, 0); |
4964 | system_long_wq = alloc_workqueue("events_long", 0, 0); |
4965 | system_unbound_wq = alloc_workqueue("events_unbound", WQ_UNBOUND, |
4966 | WQ_UNBOUND_MAX_ACTIVE); |
4967 | system_freezable_wq = alloc_workqueue("events_freezable", |
4968 | WQ_FREEZABLE, 0); |
4969 | system_power_efficient_wq = alloc_workqueue("events_power_efficient", |
4970 | WQ_POWER_EFFICIENT, 0); |
4971 | system_freezable_power_efficient_wq = alloc_workqueue("events_freezable_power_efficient", |
4972 | WQ_FREEZABLE | WQ_POWER_EFFICIENT, |
4973 | 0); |
4974 | BUG_ON(!system_wq || !system_highpri_wq || !system_long_wq || |
4975 | !system_unbound_wq || !system_freezable_wq || |
4976 | !system_power_efficient_wq || |
4977 | !system_freezable_power_efficient_wq); |
4978 | return 0; |
4979 | } |
4980 | early_initcall(init_workqueues); |
4981 |
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