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13652c4b MD |
1 | #ifndef _URCU_WORKQUEUE_FIFO_H |
2 | #define _URCU_WORKQUEUE_FIFO_H | |
3 | ||
4 | /* | |
5 | * urcu/workqueue-fifo.h | |
6 | * | |
7 | * Userspace RCU library - work queue scheme with FIFO semantic | |
8 | * | |
9 | * Copyright (c) 2014 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
10 | * | |
11 | * This library is free software; you can redistribute it and/or | |
12 | * modify it under the terms of the GNU Lesser General Public | |
13 | * License as published by the Free Software Foundation; either | |
14 | * version 2.1 of the License, or (at your option) any later version. | |
15 | * | |
16 | * This library is distributed in the hope that it will be useful, | |
17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
19 | * Lesser General Public License for more details. | |
20 | * | |
21 | * You should have received a copy of the GNU Lesser General Public | |
22 | * License along with this library; if not, write to the Free Software | |
23 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
24 | */ | |
25 | ||
26 | #include <urcu/uatomic.h> | |
7a618cf7 | 27 | #include <urcu/lfstack.h> |
13652c4b MD |
28 | #include <urcu/waitqueue-lifo.h> |
29 | #include <urcu/wfcqueue.h> | |
30 | #include <urcu/rculist.h> | |
31 | #include <pthread.h> | |
e10c65b3 | 32 | #include <assert.h> |
13652c4b | 33 | |
1b0a9891 MD |
34 | enum urcu_accept_ret { |
35 | URCU_ACCEPT_WORK = 0, | |
36 | URCU_ACCEPT_SHUTDOWN = 1, | |
37 | }; | |
38 | ||
8a2c74fe MD |
39 | enum urcu_enqueue_ret { |
40 | URCU_ENQUEUE_OK = 0, | |
41 | URCU_ENQUEUE_FULL = 1, | |
42 | }; | |
43 | ||
13652c4b MD |
44 | /* |
45 | * We use RCU to steal work from siblings. Therefore, one of RCU flavors | |
46 | * need to be included before this header. All worker that participate | |
47 | * in stealing (initialized with the URCU_WORKER_STEAL flag) need to be | |
48 | * registered RCU readers threads. | |
49 | */ | |
50 | ||
51 | struct urcu_work { | |
52 | struct cds_wfcq_node node; | |
53 | }; | |
54 | ||
55 | struct urcu_workqueue { | |
56 | /* FIFO work queue */ | |
57 | struct __cds_wfcq_head head; | |
58 | struct cds_wfcq_tail tail; | |
59 | ||
60 | /* Associated wait queue for LIFO wait/wakeup */ | |
61 | struct urcu_wait_queue waitqueue; | |
62 | ||
63 | /* RCU linked list head of siblings for work stealing. */ | |
64 | struct cds_list_head sibling_head; | |
65 | pthread_mutex_t sibling_lock; /* Protect sibling list updates */ | |
1b0a9891 | 66 | |
8a2c74fe MD |
67 | /* Maximum number of work entries (approximate). 0 means infinite. */ |
68 | unsigned long nr_work_max; | |
69 | unsigned long nr_work; /* Current number of work items */ | |
2f02be5c MD |
70 | |
71 | int worker_flags; /* Worker flags */ | |
b19099fe | 72 | int shutdown; /* Shutdown performed */ |
13652c4b MD |
73 | }; |
74 | ||
75 | struct urcu_worker { | |
a6492159 | 76 | /* Workqueue which can be either used by worker, or stolen. */ |
13652c4b MD |
77 | struct cds_wfcq_head head; |
78 | struct cds_wfcq_tail tail; | |
79 | ||
a6492159 MD |
80 | /* Work belonging to worker. Cannot be stolen. */ |
81 | struct urcu_work *own; | |
82 | ||
13652c4b MD |
83 | struct urcu_wait_node wait_node; |
84 | /* RCU linked list node of siblings for work stealing. */ | |
85 | struct cds_list_head sibling_node; | |
8a2c74fe | 86 | struct urcu_workqueue *queue; |
13652c4b MD |
87 | int flags; /* enum urcu_worker_flags */ |
88 | }; | |
89 | ||
90 | enum urcu_worker_flags { | |
91 | URCU_WORKER_STEAL = (1 << 0), | |
92 | }; | |
93 | ||
94 | static inline | |
8a2c74fe | 95 | void urcu_workqueue_init(struct urcu_workqueue *queue, |
2f02be5c MD |
96 | unsigned long max_queue_len, |
97 | int worker_flags) | |
13652c4b MD |
98 | { |
99 | __cds_wfcq_init(&queue->head, &queue->tail); | |
100 | urcu_wait_queue_init(&queue->waitqueue); | |
101 | CDS_INIT_LIST_HEAD(&queue->sibling_head); | |
8313fa62 | 102 | pthread_mutex_init(&queue->sibling_lock, NULL); |
8a2c74fe MD |
103 | queue->nr_work_max = max_queue_len; |
104 | queue->nr_work = 0; | |
1b0a9891 | 105 | queue->shutdown = false; |
13652c4b MD |
106 | } |
107 | ||
108 | static inline | |
8a2c74fe MD |
109 | enum urcu_enqueue_ret urcu_queue_work(struct urcu_workqueue *queue, |
110 | struct urcu_work *work) | |
13652c4b MD |
111 | { |
112 | bool was_empty; | |
8a2c74fe MD |
113 | unsigned long nr_work_max; |
114 | ||
115 | nr_work_max = queue->nr_work_max; | |
116 | if (nr_work_max) { | |
117 | /* Approximate max queue size. */ | |
118 | if (uatomic_read(&queue->nr_work) >= nr_work_max) | |
119 | return URCU_ENQUEUE_FULL; | |
120 | uatomic_inc(&queue->nr_work); | |
121 | } | |
13652c4b MD |
122 | cds_wfcq_node_init(&work->node); |
123 | ||
124 | /* Enqueue work. */ | |
125 | was_empty = !cds_wfcq_enqueue(&queue->head, &queue->tail, | |
126 | &work->node); | |
127 | /* | |
128 | * If workqueue was previously empty, wakeup one worker thread. | |
129 | * It will eventually grab the entire content of the work-queue | |
130 | * (therefore grabbing a "work batch"). After having grabbed the | |
131 | * work batch, while that thread is running and taking care of | |
132 | * that work batch, when we enqueue more work, we will wake | |
133 | * another thread (if there is one waiting), which will | |
134 | * eventually grab the new batch, and so on. This scheme ensures | |
135 | * that contiguous batch of work are handled by the same thread | |
136 | * (for locality), and also ensures that we scale work to many | |
137 | * worker threads when threads are busy enough to still be | |
138 | * running when work is enqueued. | |
139 | */ | |
d3afe039 MD |
140 | if (was_empty) { |
141 | rcu_read_lock(); /* Protect stack dequeue */ | |
13652c4b | 142 | (void) urcu_dequeue_wake_single(&queue->waitqueue); |
d3afe039 MD |
143 | rcu_read_unlock(); /* Protect stack dequeue */ |
144 | } | |
8a2c74fe | 145 | return URCU_ENQUEUE_OK; |
13652c4b MD |
146 | } |
147 | ||
148 | static inline | |
1b0a9891 | 149 | void __urcu_workqueue_wakeup_all(struct urcu_workqueue *queue) |
13652c4b MD |
150 | { |
151 | struct urcu_waiters waiters; | |
152 | ||
d3afe039 | 153 | rcu_read_lock(); /* Protect stack dequeue */ |
13652c4b | 154 | urcu_move_waiters(&waiters, &queue->waitqueue); |
d3afe039 MD |
155 | rcu_read_unlock(); /* Protect stack dequeue */ |
156 | ||
13652c4b MD |
157 | (void) urcu_wake_all_waiters(&waiters); |
158 | } | |
159 | ||
160 | static inline | |
8a2c74fe | 161 | void urcu_worker_init(struct urcu_workqueue *queue, |
2f02be5c | 162 | struct urcu_worker *worker) |
13652c4b MD |
163 | { |
164 | cds_wfcq_init(&worker->head, &worker->tail); | |
13652c4b | 165 | urcu_wait_node_init(&worker->wait_node, URCU_WAIT_RUNNING); |
a6492159 | 166 | worker->own = NULL; |
db9916c6 | 167 | worker->wait_node.node.next = NULL; |
8a2c74fe | 168 | worker->queue = queue; |
2f02be5c | 169 | worker->flags = queue->worker_flags; |
13652c4b MD |
170 | } |
171 | ||
172 | static inline | |
173 | void urcu_worker_register(struct urcu_workqueue *queue, | |
174 | struct urcu_worker *worker) | |
175 | { | |
176 | if (worker->flags & URCU_WORKER_STEAL) { | |
177 | pthread_mutex_lock(&queue->sibling_lock); | |
178 | cds_list_add_rcu(&worker->sibling_node, &queue->sibling_head); | |
179 | pthread_mutex_unlock(&queue->sibling_lock); | |
180 | } | |
181 | } | |
182 | ||
183 | static inline | |
184 | void urcu_worker_unregister(struct urcu_workqueue *queue, | |
185 | struct urcu_worker *worker) | |
186 | { | |
187 | enum cds_wfcq_ret wfcq_ret; | |
188 | ||
189 | if (worker->flags & URCU_WORKER_STEAL) { | |
190 | pthread_mutex_lock(&queue->sibling_lock); | |
191 | cds_list_del_rcu(&worker->sibling_node); | |
192 | pthread_mutex_unlock(&queue->sibling_lock); | |
13652c4b MD |
193 | } |
194 | ||
d3afe039 | 195 | /* |
6e17009c | 196 | * Make sure we are removed from waitqueue. |
d3afe039 | 197 | */ |
aa46e09f | 198 | if (urcu_in_waitqueue(&worker->wait_node)) |
6e17009c | 199 | __urcu_workqueue_wakeup_all(queue); |
d3afe039 | 200 | |
13652c4b MD |
201 | /* |
202 | * Put any local work we still have back into the workqueue. | |
203 | */ | |
204 | wfcq_ret = __cds_wfcq_splice_blocking(&queue->head, | |
205 | &queue->tail, | |
206 | &worker->head, | |
207 | &worker->tail); | |
208 | if (wfcq_ret != CDS_WFCQ_RET_SRC_EMPTY | |
209 | && wfcq_ret == CDS_WFCQ_RET_DEST_EMPTY) { | |
210 | /* | |
211 | * Wakeup worker thread if we have put work back into | |
212 | * workqueue that was previously empty. | |
213 | */ | |
d3afe039 | 214 | rcu_read_lock(); /* Protect stack dequeue */ |
13652c4b | 215 | (void) urcu_dequeue_wake_single(&queue->waitqueue); |
d3afe039 | 216 | rcu_read_unlock(); /* Protect stack dequeue */ |
13652c4b | 217 | } |
6e17009c MD |
218 | |
219 | /* | |
220 | * Wait for grace period before freeing or reusing | |
221 | * "worker" because used by RCU linked list. | |
222 | * Also prevents ABA for waitqueue stack dequeue: matches RCU | |
223 | * read-side critical sections around dequeue and move all | |
224 | * operations on waitqueue). | |
225 | */ | |
226 | synchronize_rcu(); | |
13652c4b MD |
227 | } |
228 | ||
13652c4b | 229 | static inline |
a6492159 MD |
230 | bool ___urcu_grab_work(struct urcu_worker *worker, |
231 | cds_wfcq_head_ptr_t src_head, | |
232 | struct cds_wfcq_tail *src_tail, | |
233 | bool steal) | |
13652c4b | 234 | { |
e10c65b3 | 235 | enum cds_wfcq_ret splice_ret; |
8313fa62 | 236 | struct __cds_wfcq_head tmp_head; |
a6492159 MD |
237 | struct cds_wfcq_tail tmp_tail; |
238 | struct cds_wfcq_node *node; | |
e10c65b3 | 239 | |
30926570 | 240 | /* |
a6492159 | 241 | * Don't bother grabbing the src queue lock if it is empty. |
30926570 | 242 | */ |
a6492159 | 243 | if (cds_wfcq_empty(src_head, src_tail)) |
e10c65b3 | 244 | return false; |
8313fa62 | 245 | __cds_wfcq_init(&tmp_head, &tmp_tail); |
a6492159 MD |
246 | |
247 | /* Ensure that we preserve FIFO work order. */ | |
248 | assert(!steal || worker->own == NULL); | |
249 | ||
250 | /* Splice to temporary queue. */ | |
251 | if (steal) | |
252 | cds_wfcq_dequeue_lock(src_head.h, src_tail); | |
253 | splice_ret = __cds_wfcq_splice_blocking(&tmp_head, | |
254 | &tmp_tail, | |
255 | src_head, | |
256 | src_tail); | |
257 | if (steal) | |
258 | cds_wfcq_dequeue_unlock(src_head.h, src_tail); | |
259 | if (splice_ret == CDS_WFCQ_RET_SRC_EMPTY) | |
260 | return false; | |
261 | ||
262 | /* | |
263 | * Keep one work entry for ourself. This ensures forward | |
264 | * progress amongst stealing co-workers. This also ensures that | |
265 | * when a worker grab some work from the global workqueue, it | |
266 | * will have at least one work item to deal with. | |
267 | */ | |
268 | if (worker->own == NULL) { | |
269 | if (!steal) { | |
270 | /* | |
271 | * Try to grab own work from worker workqueue to | |
272 | * preserve FIFO order. | |
273 | */ | |
274 | node = cds_wfcq_dequeue_blocking(&worker->head, | |
275 | &worker->tail); | |
276 | if (node) | |
277 | goto got_node; | |
278 | } | |
279 | node = __cds_wfcq_dequeue_blocking(&tmp_head, &tmp_tail); | |
280 | assert(node != NULL); | |
281 | got_node: | |
282 | worker->own = caa_container_of(node, struct urcu_work, node); | |
283 | } | |
284 | ||
285 | /* Splice into worker workqueue. */ | |
8313fa62 | 286 | splice_ret = __cds_wfcq_splice_blocking(&worker->head, |
13652c4b | 287 | &worker->tail, |
a6492159 MD |
288 | &tmp_head, |
289 | &tmp_tail); | |
e10c65b3 | 290 | /* Ensure that we preserve FIFO work order. */ |
a6492159 MD |
291 | assert(!steal || splice_ret != CDS_WFCQ_RET_DEST_NON_EMPTY); |
292 | return true; | |
293 | } | |
294 | ||
295 | /* | |
296 | * Try stealing work from siblings when we have nothing to do. | |
297 | */ | |
298 | static inline | |
299 | bool ___urcu_steal_work(struct urcu_worker *worker, | |
300 | struct urcu_worker *sibling) | |
301 | { | |
302 | return ___urcu_grab_work(worker, &sibling->head, &sibling->tail, 1); | |
13652c4b MD |
303 | } |
304 | ||
305 | static inline | |
e10c65b3 | 306 | bool __urcu_steal_work(struct urcu_workqueue *queue, |
13652c4b MD |
307 | struct urcu_worker *worker) |
308 | { | |
309 | struct urcu_worker *sibling_prev, *sibling_next; | |
310 | struct cds_list_head *sibling_node; | |
e10c65b3 | 311 | bool steal_performed = 0; |
13652c4b MD |
312 | |
313 | if (!(worker->flags & URCU_WORKER_STEAL)) | |
e10c65b3 | 314 | return false; |
13652c4b MD |
315 | |
316 | rcu_read_lock(); | |
317 | ||
318 | sibling_node = rcu_dereference(worker->sibling_node.next); | |
319 | if (sibling_node == &queue->sibling_head) | |
320 | sibling_node = rcu_dereference(sibling_node->next); | |
321 | sibling_next = caa_container_of(sibling_node, struct urcu_worker, | |
322 | sibling_node); | |
323 | if (sibling_next != worker) | |
e10c65b3 MD |
324 | steal_performed = ___urcu_steal_work(worker, sibling_next); |
325 | if (steal_performed) | |
326 | goto end; | |
13652c4b MD |
327 | |
328 | sibling_node = rcu_dereference(worker->sibling_node.prev); | |
329 | if (sibling_node == &queue->sibling_head) | |
330 | sibling_node = rcu_dereference(sibling_node->prev); | |
331 | sibling_prev = caa_container_of(sibling_node, struct urcu_worker, | |
332 | sibling_node); | |
333 | if (sibling_prev != worker && sibling_prev != sibling_next) | |
e10c65b3 MD |
334 | steal_performed = ___urcu_steal_work(worker, sibling_prev); |
335 | end: | |
13652c4b MD |
336 | rcu_read_unlock(); |
337 | ||
e10c65b3 | 338 | return steal_performed; |
13652c4b MD |
339 | } |
340 | ||
341 | static inline | |
5d30bf32 | 342 | bool ___urcu_wakeup_sibling(struct urcu_worker *sibling) |
13652c4b | 343 | { |
5d30bf32 | 344 | return urcu_adaptative_wake_up(&sibling->wait_node); |
13652c4b MD |
345 | } |
346 | ||
347 | static inline | |
5d30bf32 | 348 | bool __urcu_wakeup_siblings(struct urcu_workqueue *queue, |
13652c4b MD |
349 | struct urcu_worker *worker) |
350 | { | |
351 | struct urcu_worker *sibling_prev, *sibling_next; | |
352 | struct cds_list_head *sibling_node; | |
5d30bf32 | 353 | bool wakeup_performed = 0; |
13652c4b MD |
354 | |
355 | if (!(worker->flags & URCU_WORKER_STEAL)) | |
356 | return; | |
357 | ||
358 | /* Only wakeup siblings if we have work in our own queue. */ | |
359 | if (cds_wfcq_empty(&worker->head, &worker->tail)) | |
360 | return; | |
361 | ||
362 | rcu_read_lock(); | |
363 | ||
364 | sibling_node = rcu_dereference(worker->sibling_node.next); | |
365 | if (sibling_node == &queue->sibling_head) | |
366 | sibling_node = rcu_dereference(sibling_node->next); | |
367 | sibling_next = caa_container_of(sibling_node, struct urcu_worker, | |
368 | sibling_node); | |
369 | if (sibling_next != worker) | |
5d30bf32 MD |
370 | wakeup_performed = ___urcu_wakeup_sibling(sibling_next); |
371 | if (wakeup_performed) | |
372 | goto end; | |
13652c4b MD |
373 | |
374 | sibling_node = rcu_dereference(worker->sibling_node.prev); | |
375 | if (sibling_node == &queue->sibling_head) | |
376 | sibling_node = rcu_dereference(sibling_node->prev); | |
377 | sibling_prev = caa_container_of(sibling_node, struct urcu_worker, | |
378 | sibling_node); | |
379 | if (sibling_prev != worker && sibling_prev != sibling_next) | |
5d30bf32 MD |
380 | wakeup_performed = ___urcu_wakeup_sibling(sibling_prev); |
381 | end: | |
13652c4b | 382 | rcu_read_unlock(); |
5d30bf32 MD |
383 | |
384 | return wakeup_performed; | |
13652c4b MD |
385 | } |
386 | ||
387 | static inline | |
8a2c74fe | 388 | enum urcu_accept_ret urcu_accept_work(struct urcu_worker *worker) |
13652c4b | 389 | { |
8a2c74fe | 390 | struct urcu_workqueue *queue = worker->queue; |
13652c4b | 391 | enum cds_wfcq_ret wfcq_ret; |
a6492159 | 392 | bool has_work; |
13652c4b | 393 | |
a6492159 | 394 | has_work = ___urcu_grab_work(worker, &queue->head, &queue->tail, 0); |
13652c4b | 395 | /* Don't wait if we have work to do. */ |
0a14cd14 MD |
396 | if (has_work || worker->own |
397 | || !cds_wfcq_empty(&worker->head, &worker->tail)) | |
13652c4b MD |
398 | goto do_work; |
399 | /* Try to steal work from sibling instead of blocking */ | |
400 | if (__urcu_steal_work(queue, worker)) | |
401 | goto do_work; | |
1b0a9891 MD |
402 | /* No more work to do, check shutdown state */ |
403 | if (CMM_LOAD_SHARED(queue->shutdown)) | |
404 | return URCU_ACCEPT_SHUTDOWN; | |
13652c4b MD |
405 | urcu_wait_set_state(&worker->wait_node, |
406 | URCU_WAIT_WAITING); | |
aa46e09f | 407 | if (!urcu_in_waitqueue(&worker->wait_node)) { |
13652c4b MD |
408 | int was_empty; |
409 | ||
d3afe039 MD |
410 | /* Protect stack dequeue against ABA */ |
411 | synchronize_rcu(); | |
13652c4b MD |
412 | was_empty = !urcu_wait_add(&queue->waitqueue, |
413 | &worker->wait_node); | |
414 | /* | |
415 | * If the wait queue was empty, it means we are the | |
416 | * first thread to be put back into an otherwise empty | |
417 | * wait queue. Re-check if work queue is empty after | |
418 | * adding ourself to wait queue, so we can wakeup the | |
419 | * top of wait queue since new work have appeared, and | |
420 | * work enqueuer may not have seen that it needed to do | |
421 | * a wake up. | |
422 | */ | |
423 | if (was_empty && !cds_wfcq_empty(&queue->head, | |
d3afe039 MD |
424 | &queue->tail)) { |
425 | rcu_read_lock(); /* Protect stack dequeue */ | |
13652c4b | 426 | (void) urcu_dequeue_wake_single(&queue->waitqueue); |
d3afe039 MD |
427 | rcu_read_unlock(); /* Protect stack dequeue */ |
428 | } | |
13652c4b MD |
429 | } else { |
430 | /* | |
aa46e09f MD |
431 | * We are in the queue, or the dispatcher just removed |
432 | * us from it (after we read the next pointer), and is | |
433 | * therefore awakening us. The state will therefore have | |
434 | * been changed from WAITING to some other state, which | |
435 | * will let the busy wait pass through. | |
13652c4b MD |
436 | */ |
437 | } | |
438 | urcu_adaptative_busy_wait(&worker->wait_node); | |
439 | return; | |
440 | ||
441 | do_work: | |
442 | /* | |
443 | * We will be busy handling the work batch, awaken siblings so | |
444 | * they can steal from us. | |
445 | */ | |
5d30bf32 | 446 | (void) __urcu_wakeup_siblings(queue, worker); |
1b0a9891 | 447 | return URCU_ACCEPT_WORK; |
13652c4b MD |
448 | } |
449 | ||
450 | static inline | |
451 | struct urcu_work *urcu_dequeue_work(struct urcu_worker *worker) | |
452 | { | |
8a2c74fe | 453 | struct urcu_workqueue *queue = worker->queue; |
13652c4b | 454 | struct cds_wfcq_node *node; |
8a2c74fe | 455 | struct urcu_work *work; |
13652c4b | 456 | |
a6492159 | 457 | if (worker->own) { |
a6492159 MD |
458 | /* Process our own work entry. */ |
459 | work = worker->own; | |
460 | worker->own = NULL; | |
8a2c74fe | 461 | goto end; |
a6492159 | 462 | } |
13652c4b MD |
463 | /* |
464 | * If we are registered for work stealing, we need to dequeue | |
465 | * safely against siblings. | |
466 | */ | |
30926570 MD |
467 | if (worker->flags & URCU_WORKER_STEAL) { |
468 | /* | |
469 | * Don't bother grabbing the worker queue lock if it is | |
470 | * empty. | |
471 | */ | |
472 | if (cds_wfcq_empty(&worker->head, &worker->tail)) | |
473 | return NULL; | |
13652c4b MD |
474 | node = cds_wfcq_dequeue_blocking(&worker->head, |
475 | &worker->tail); | |
30926570 | 476 | } else { |
13652c4b MD |
477 | node = ___cds_wfcq_dequeue_with_state(&worker->head, |
478 | &worker->tail, NULL, 1, 0); | |
30926570 | 479 | } |
13652c4b MD |
480 | if (!node) |
481 | return NULL; | |
8a2c74fe MD |
482 | work = caa_container_of(node, struct urcu_work, node); |
483 | end: | |
484 | if (queue->nr_work_max) | |
485 | uatomic_dec(&queue->nr_work); | |
486 | return work; | |
13652c4b MD |
487 | } |
488 | ||
1b0a9891 MD |
489 | static inline |
490 | void urcu_workqueue_shutdown(struct urcu_workqueue *queue) | |
491 | { | |
492 | /* Set shutdown */ | |
493 | CMM_STORE_SHARED(queue->shutdown, true); | |
494 | /* Wakeup all workers */ | |
495 | __urcu_workqueue_wakeup_all(queue); | |
496 | } | |
497 | ||
f00ae188 MD |
498 | /* |
499 | * Use to let dispatcher steal work from the entire queue in case of | |
500 | * stall. The "worker" parameter need to be intialized, but is usually | |
501 | * not registered. | |
502 | */ | |
503 | static inline | |
504 | bool urcu_workqueue_steal_all(struct urcu_workqueue *queue, | |
505 | struct urcu_worker *worker) | |
506 | { | |
507 | struct urcu_worker *sibling; | |
508 | bool has_work = false; | |
509 | ||
2e1ced1f MD |
510 | if (worker->flags & URCU_WORKER_STEAL) { |
511 | rcu_read_lock(); | |
512 | /* Steal from each worker */ | |
513 | cds_list_for_each_entry_rcu(sibling, &queue->sibling_head, | |
514 | sibling_node) | |
515 | has_work |= ___urcu_grab_work(worker, &sibling->head, | |
516 | &sibling->tail, 1); | |
517 | rcu_read_unlock(); | |
518 | } | |
f00ae188 MD |
519 | |
520 | /* Steal from global workqueue */ | |
521 | has_work |= ___urcu_grab_work(worker, &queue->head, &queue->tail, 0); | |
522 | return has_work; | |
523 | } | |
524 | ||
13652c4b | 525 | #endif /* _URCU_WORKQUEUE_FIFO_H */ |