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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
801c1419 | 2 | |
b8a21626 PZ |
3 | /* |
4 | * Generic wait-for-completion handler; | |
5 | * | |
6 | * It differs from semaphores in that their default case is the opposite, | |
7 | * wait_for_completion default blocks whereas semaphore default non-block. The | |
8 | * interface also makes it easy to 'complete' multiple waiting threads, | |
9 | * something which isn't entirely natural for semaphores. | |
10 | * | |
11 | * But more importantly, the primitive documents the usage. Semaphores would | |
12 | * typically be used for exclusion which gives rise to priority inversion. | |
13 | * Waiting for completion is a typically sync point, but not an exclusion point. | |
14 | */ | |
b8a21626 | 15 | |
6f63904c AV |
16 | static void complete_with_flags(struct completion *x, int wake_flags) |
17 | { | |
18 | unsigned long flags; | |
19 | ||
20 | raw_spin_lock_irqsave(&x->wait.lock, flags); | |
21 | ||
22 | if (x->done != UINT_MAX) | |
23 | x->done++; | |
24 | swake_up_locked(&x->wait, wake_flags); | |
25 | raw_spin_unlock_irqrestore(&x->wait.lock, flags); | |
26 | } | |
27 | ||
28 | void complete_on_current_cpu(struct completion *x) | |
29 | { | |
30 | return complete_with_flags(x, WF_CURRENT_CPU); | |
31 | } | |
32 | ||
b8a21626 PZ |
33 | /** |
34 | * complete: - signals a single thread waiting on this completion | |
35 | * @x: holds the state of this particular completion | |
36 | * | |
37 | * This will wake up a single thread waiting on this completion. Threads will be | |
38 | * awakened in the same order in which they were queued. | |
39 | * | |
40 | * See also complete_all(), wait_for_completion() and related routines. | |
41 | * | |
7696f991 AP |
42 | * If this function wakes up a task, it executes a full memory barrier before |
43 | * accessing the task state. | |
b8a21626 PZ |
44 | */ |
45 | void complete(struct completion *x) | |
46 | { | |
6f63904c | 47 | complete_with_flags(x, 0); |
b8a21626 PZ |
48 | } |
49 | EXPORT_SYMBOL(complete); | |
50 | ||
51 | /** | |
52 | * complete_all: - signals all threads waiting on this completion | |
53 | * @x: holds the state of this particular completion | |
54 | * | |
55 | * This will wake up all threads waiting on this particular completion event. | |
56 | * | |
7696f991 AP |
57 | * If this function wakes up a task, it executes a full memory barrier before |
58 | * accessing the task state. | |
9c878320 SR |
59 | * |
60 | * Since complete_all() sets the completion of @x permanently to done | |
61 | * to allow multiple waiters to finish, a call to reinit_completion() | |
62 | * must be used on @x if @x is to be used again. The code must make | |
63 | * sure that all waiters have woken and finished before reinitializing | |
64 | * @x. Also note that the function completion_done() can not be used | |
65 | * to know if there are still waiters after complete_all() has been called. | |
b8a21626 PZ |
66 | */ |
67 | void complete_all(struct completion *x) | |
68 | { | |
69 | unsigned long flags; | |
70 | ||
8bf6c677 | 71 | lockdep_assert_RT_in_threaded_ctx(); |
a5c6234e TG |
72 | |
73 | raw_spin_lock_irqsave(&x->wait.lock, flags); | |
da9647e0 | 74 | x->done = UINT_MAX; |
a5c6234e TG |
75 | swake_up_all_locked(&x->wait); |
76 | raw_spin_unlock_irqrestore(&x->wait.lock, flags); | |
b8a21626 PZ |
77 | } |
78 | EXPORT_SYMBOL(complete_all); | |
79 | ||
80 | static inline long __sched | |
81 | do_wait_for_common(struct completion *x, | |
82 | long (*action)(long), long timeout, int state) | |
83 | { | |
84 | if (!x->done) { | |
a5c6234e | 85 | DECLARE_SWAITQUEUE(wait); |
b8a21626 | 86 | |
b8a21626 PZ |
87 | do { |
88 | if (signal_pending_state(state, current)) { | |
89 | timeout = -ERESTARTSYS; | |
90 | break; | |
91 | } | |
a5c6234e | 92 | __prepare_to_swait(&x->wait, &wait); |
b8a21626 | 93 | __set_current_state(state); |
a5c6234e | 94 | raw_spin_unlock_irq(&x->wait.lock); |
b8a21626 | 95 | timeout = action(timeout); |
a5c6234e | 96 | raw_spin_lock_irq(&x->wait.lock); |
b8a21626 | 97 | } while (!x->done && timeout); |
a5c6234e | 98 | __finish_swait(&x->wait, &wait); |
b8a21626 PZ |
99 | if (!x->done) |
100 | return timeout; | |
101 | } | |
da9647e0 PZ |
102 | if (x->done != UINT_MAX) |
103 | x->done--; | |
b8a21626 PZ |
104 | return timeout ?: 1; |
105 | } | |
106 | ||
107 | static inline long __sched | |
108 | __wait_for_common(struct completion *x, | |
109 | long (*action)(long), long timeout, int state) | |
110 | { | |
111 | might_sleep(); | |
112 | ||
cd8084f9 BP |
113 | complete_acquire(x); |
114 | ||
a5c6234e | 115 | raw_spin_lock_irq(&x->wait.lock); |
b8a21626 | 116 | timeout = do_wait_for_common(x, action, timeout, state); |
a5c6234e | 117 | raw_spin_unlock_irq(&x->wait.lock); |
cd8084f9 BP |
118 | |
119 | complete_release(x); | |
120 | ||
b8a21626 PZ |
121 | return timeout; |
122 | } | |
123 | ||
124 | static long __sched | |
125 | wait_for_common(struct completion *x, long timeout, int state) | |
126 | { | |
127 | return __wait_for_common(x, schedule_timeout, timeout, state); | |
128 | } | |
129 | ||
130 | static long __sched | |
131 | wait_for_common_io(struct completion *x, long timeout, int state) | |
132 | { | |
133 | return __wait_for_common(x, io_schedule_timeout, timeout, state); | |
134 | } | |
135 | ||
136 | /** | |
137 | * wait_for_completion: - waits for completion of a task | |
138 | * @x: holds the state of this particular completion | |
139 | * | |
140 | * This waits to be signaled for completion of a specific task. It is NOT | |
141 | * interruptible and there is no timeout. | |
142 | * | |
143 | * See also similar routines (i.e. wait_for_completion_timeout()) with timeout | |
144 | * and interrupt capability. Also see complete(). | |
145 | */ | |
146 | void __sched wait_for_completion(struct completion *x) | |
147 | { | |
148 | wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE); | |
149 | } | |
150 | EXPORT_SYMBOL(wait_for_completion); | |
151 | ||
152 | /** | |
153 | * wait_for_completion_timeout: - waits for completion of a task (w/timeout) | |
154 | * @x: holds the state of this particular completion | |
155 | * @timeout: timeout value in jiffies | |
156 | * | |
157 | * This waits for either a completion of a specific task to be signaled or for a | |
158 | * specified timeout to expire. The timeout is in jiffies. It is not | |
159 | * interruptible. | |
160 | * | |
161 | * Return: 0 if timed out, and positive (at least 1, or number of jiffies left | |
162 | * till timeout) if completed. | |
163 | */ | |
164 | unsigned long __sched | |
165 | wait_for_completion_timeout(struct completion *x, unsigned long timeout) | |
166 | { | |
167 | return wait_for_common(x, timeout, TASK_UNINTERRUPTIBLE); | |
168 | } | |
169 | EXPORT_SYMBOL(wait_for_completion_timeout); | |
170 | ||
171 | /** | |
172 | * wait_for_completion_io: - waits for completion of a task | |
173 | * @x: holds the state of this particular completion | |
174 | * | |
175 | * This waits to be signaled for completion of a specific task. It is NOT | |
176 | * interruptible and there is no timeout. The caller is accounted as waiting | |
a1bd5373 | 177 | * for IO (which traditionally means blkio only). |
b8a21626 PZ |
178 | */ |
179 | void __sched wait_for_completion_io(struct completion *x) | |
180 | { | |
181 | wait_for_common_io(x, MAX_SCHEDULE_TIMEOUT, TASK_UNINTERRUPTIBLE); | |
182 | } | |
183 | EXPORT_SYMBOL(wait_for_completion_io); | |
184 | ||
185 | /** | |
186 | * wait_for_completion_io_timeout: - waits for completion of a task (w/timeout) | |
187 | * @x: holds the state of this particular completion | |
188 | * @timeout: timeout value in jiffies | |
189 | * | |
190 | * This waits for either a completion of a specific task to be signaled or for a | |
191 | * specified timeout to expire. The timeout is in jiffies. It is not | |
a1bd5373 WS |
192 | * interruptible. The caller is accounted as waiting for IO (which traditionally |
193 | * means blkio only). | |
b8a21626 PZ |
194 | * |
195 | * Return: 0 if timed out, and positive (at least 1, or number of jiffies left | |
196 | * till timeout) if completed. | |
197 | */ | |
198 | unsigned long __sched | |
199 | wait_for_completion_io_timeout(struct completion *x, unsigned long timeout) | |
200 | { | |
201 | return wait_for_common_io(x, timeout, TASK_UNINTERRUPTIBLE); | |
202 | } | |
203 | EXPORT_SYMBOL(wait_for_completion_io_timeout); | |
204 | ||
205 | /** | |
206 | * wait_for_completion_interruptible: - waits for completion of a task (w/intr) | |
207 | * @x: holds the state of this particular completion | |
208 | * | |
209 | * This waits for completion of a specific task to be signaled. It is | |
210 | * interruptible. | |
211 | * | |
212 | * Return: -ERESTARTSYS if interrupted, 0 if completed. | |
213 | */ | |
214 | int __sched wait_for_completion_interruptible(struct completion *x) | |
215 | { | |
216 | long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_INTERRUPTIBLE); | |
929659ac | 217 | |
b8a21626 PZ |
218 | if (t == -ERESTARTSYS) |
219 | return t; | |
220 | return 0; | |
221 | } | |
222 | EXPORT_SYMBOL(wait_for_completion_interruptible); | |
223 | ||
224 | /** | |
225 | * wait_for_completion_interruptible_timeout: - waits for completion (w/(to,intr)) | |
226 | * @x: holds the state of this particular completion | |
227 | * @timeout: timeout value in jiffies | |
228 | * | |
229 | * This waits for either a completion of a specific task to be signaled or for a | |
230 | * specified timeout to expire. It is interruptible. The timeout is in jiffies. | |
231 | * | |
232 | * Return: -ERESTARTSYS if interrupted, 0 if timed out, positive (at least 1, | |
233 | * or number of jiffies left till timeout) if completed. | |
234 | */ | |
235 | long __sched | |
236 | wait_for_completion_interruptible_timeout(struct completion *x, | |
237 | unsigned long timeout) | |
238 | { | |
239 | return wait_for_common(x, timeout, TASK_INTERRUPTIBLE); | |
240 | } | |
241 | EXPORT_SYMBOL(wait_for_completion_interruptible_timeout); | |
242 | ||
243 | /** | |
244 | * wait_for_completion_killable: - waits for completion of a task (killable) | |
245 | * @x: holds the state of this particular completion | |
246 | * | |
247 | * This waits to be signaled for completion of a specific task. It can be | |
248 | * interrupted by a kill signal. | |
249 | * | |
250 | * Return: -ERESTARTSYS if interrupted, 0 if completed. | |
251 | */ | |
252 | int __sched wait_for_completion_killable(struct completion *x) | |
253 | { | |
254 | long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, TASK_KILLABLE); | |
929659ac | 255 | |
b8a21626 PZ |
256 | if (t == -ERESTARTSYS) |
257 | return t; | |
258 | return 0; | |
259 | } | |
260 | EXPORT_SYMBOL(wait_for_completion_killable); | |
261 | ||
929659ac PZ |
262 | int __sched wait_for_completion_state(struct completion *x, unsigned int state) |
263 | { | |
264 | long t = wait_for_common(x, MAX_SCHEDULE_TIMEOUT, state); | |
265 | ||
266 | if (t == -ERESTARTSYS) | |
267 | return t; | |
268 | return 0; | |
269 | } | |
270 | EXPORT_SYMBOL(wait_for_completion_state); | |
271 | ||
b8a21626 PZ |
272 | /** |
273 | * wait_for_completion_killable_timeout: - waits for completion of a task (w/(to,killable)) | |
274 | * @x: holds the state of this particular completion | |
275 | * @timeout: timeout value in jiffies | |
276 | * | |
277 | * This waits for either a completion of a specific task to be | |
278 | * signaled or for a specified timeout to expire. It can be | |
279 | * interrupted by a kill signal. The timeout is in jiffies. | |
280 | * | |
281 | * Return: -ERESTARTSYS if interrupted, 0 if timed out, positive (at least 1, | |
282 | * or number of jiffies left till timeout) if completed. | |
283 | */ | |
284 | long __sched | |
285 | wait_for_completion_killable_timeout(struct completion *x, | |
286 | unsigned long timeout) | |
287 | { | |
288 | return wait_for_common(x, timeout, TASK_KILLABLE); | |
289 | } | |
290 | EXPORT_SYMBOL(wait_for_completion_killable_timeout); | |
291 | ||
292 | /** | |
293 | * try_wait_for_completion - try to decrement a completion without blocking | |
294 | * @x: completion structure | |
295 | * | |
296 | * Return: 0 if a decrement cannot be done without blocking | |
297 | * 1 if a decrement succeeded. | |
298 | * | |
299 | * If a completion is being used as a counting completion, | |
300 | * attempt to decrement the counter without blocking. This | |
301 | * enables us to avoid waiting if the resource the completion | |
302 | * is protecting is not available. | |
303 | */ | |
304 | bool try_wait_for_completion(struct completion *x) | |
305 | { | |
306 | unsigned long flags; | |
d17067e4 | 307 | bool ret = true; |
b8a21626 | 308 | |
7c34e318 NMG |
309 | /* |
310 | * Since x->done will need to be locked only | |
311 | * in the non-blocking case, we check x->done | |
312 | * first without taking the lock so we can | |
313 | * return early in the blocking case. | |
314 | */ | |
bc956015 | 315 | if (!READ_ONCE(x->done)) |
d17067e4 | 316 | return false; |
7c34e318 | 317 | |
a5c6234e | 318 | raw_spin_lock_irqsave(&x->wait.lock, flags); |
b8a21626 | 319 | if (!x->done) |
d17067e4 | 320 | ret = false; |
da9647e0 | 321 | else if (x->done != UINT_MAX) |
b8a21626 | 322 | x->done--; |
a5c6234e | 323 | raw_spin_unlock_irqrestore(&x->wait.lock, flags); |
b8a21626 PZ |
324 | return ret; |
325 | } | |
326 | EXPORT_SYMBOL(try_wait_for_completion); | |
327 | ||
328 | /** | |
329 | * completion_done - Test to see if a completion has any waiters | |
330 | * @x: completion structure | |
331 | * | |
332 | * Return: 0 if there are waiters (wait_for_completion() in progress) | |
333 | * 1 if there are no waiters. | |
334 | * | |
9c878320 | 335 | * Note, this will always return true if complete_all() was called on @X. |
b8a21626 PZ |
336 | */ |
337 | bool completion_done(struct completion *x) | |
338 | { | |
dec13c42 PM |
339 | unsigned long flags; |
340 | ||
bc956015 ON |
341 | if (!READ_ONCE(x->done)) |
342 | return false; | |
343 | ||
344 | /* | |
345 | * If ->done, we need to wait for complete() to release ->wait.lock | |
346 | * otherwise we can end up freeing the completion before complete() | |
347 | * is done referencing it. | |
bc956015 | 348 | */ |
a5c6234e TG |
349 | raw_spin_lock_irqsave(&x->wait.lock, flags); |
350 | raw_spin_unlock_irqrestore(&x->wait.lock, flags); | |
bc956015 | 351 | return true; |
b8a21626 PZ |
352 | } |
353 | EXPORT_SYMBOL(completion_done); |