1 /*-
2 * Copyright (c) 2000 Doug Rabson
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD: releng/10.3/sys/kern/subr_taskqueue.c 262065 2014-02-17 15:32:08Z avg $");
29
30 #include <sys/param.h>
31 #include <sys/systm.h>
32 #include <sys/bus.h>
33 #include <sys/interrupt.h>
34 #include <sys/kernel.h>
35 #include <sys/kthread.h>
36 #include <sys/limits.h>
37 #include <sys/lock.h>
38 #include <sys/malloc.h>
39 #include <sys/mutex.h>
40 #include <sys/proc.h>
41 #include <sys/sched.h>
42 #include <sys/taskqueue.h>
43 #include <sys/unistd.h>
44 #include <machine/stdarg.h>
45
46 static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
47 static void *taskqueue_giant_ih;
48 static void *taskqueue_ih;
49
50 struct taskqueue_busy {
51 struct task *tb_running;
52 TAILQ_ENTRY(taskqueue_busy) tb_link;
53 };
54
55 struct taskqueue {
56 STAILQ_HEAD(, task) tq_queue;
57 taskqueue_enqueue_fn tq_enqueue;
58 void *tq_context;
59 TAILQ_HEAD(, taskqueue_busy) tq_active;
60 struct mtx tq_mutex;
61 struct thread **tq_threads;
62 int tq_tcount;
63 int tq_spin;
64 int tq_flags;
65 int tq_callouts;
66 taskqueue_callback_fn tq_callbacks[TASKQUEUE_NUM_CALLBACKS];
67 void *tq_cb_contexts[TASKQUEUE_NUM_CALLBACKS];
68 };
69
70 #define TQ_FLAGS_ACTIVE (1 << 0)
71 #define TQ_FLAGS_BLOCKED (1 << 1)
72 #define TQ_FLAGS_PENDING (1 << 2)
73
74 #define DT_CALLOUT_ARMED (1 << 0)
75
76 #define TQ_LOCK(tq) \
77 do { \
78 if ((tq)->tq_spin) \
79 mtx_lock_spin(&(tq)->tq_mutex); \
80 else \
81 mtx_lock(&(tq)->tq_mutex); \
82 } while (0)
83 #define TQ_ASSERT_LOCKED(tq) mtx_assert(&(tq)->tq_mutex, MA_OWNED)
84
85 #define TQ_UNLOCK(tq) \
86 do { \
87 if ((tq)->tq_spin) \
88 mtx_unlock_spin(&(tq)->tq_mutex); \
89 else \
90 mtx_unlock(&(tq)->tq_mutex); \
91 } while (0)
92 #define TQ_ASSERT_UNLOCKED(tq) mtx_assert(&(tq)->tq_mutex, MA_NOTOWNED)
93
94 void
95 _timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
96 int priority, task_fn_t func, void *context)
97 {
98
99 TASK_INIT(&timeout_task->t, priority, func, context);
100 callout_init_mtx(&timeout_task->c, &queue->tq_mutex, 0);
101 timeout_task->q = queue;
102 timeout_task->f = 0;
103 }
104
105 static __inline int
106 TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm,
107 int t)
108 {
109 if (tq->tq_spin)
110 return (msleep_spin(p, m, wm, t));
111 return (msleep(p, m, pri, wm, t));
112 }
113
114 static struct taskqueue *
115 _taskqueue_create(const char *name __unused, int mflags,
116 taskqueue_enqueue_fn enqueue, void *context,
117 int mtxflags, const char *mtxname)
118 {
119 struct taskqueue *queue;
120
121 queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
122 if (!queue)
123 return NULL;
124
125 STAILQ_INIT(&queue->tq_queue);
126 TAILQ_INIT(&queue->tq_active);
127 queue->tq_enqueue = enqueue;
128 queue->tq_context = context;
129 queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
130 queue->tq_flags |= TQ_FLAGS_ACTIVE;
131 mtx_init(&queue->tq_mutex, mtxname, NULL, mtxflags);
132
133 return queue;
134 }
135
136 struct taskqueue *
137 taskqueue_create(const char *name, int mflags,
138 taskqueue_enqueue_fn enqueue, void *context)
139 {
140 return _taskqueue_create(name, mflags, enqueue, context,
141 MTX_DEF, "taskqueue");
142 }
143
144 void
145 taskqueue_set_callback(struct taskqueue *queue,
146 enum taskqueue_callback_type cb_type, taskqueue_callback_fn callback,
147 void *context)
148 {
149
150 KASSERT(((cb_type >= TASKQUEUE_CALLBACK_TYPE_MIN) &&
151 (cb_type <= TASKQUEUE_CALLBACK_TYPE_MAX)),
152 ("Callback type %d not valid, must be %d-%d", cb_type,
153 TASKQUEUE_CALLBACK_TYPE_MIN, TASKQUEUE_CALLBACK_TYPE_MAX));
154 KASSERT((queue->tq_callbacks[cb_type] == NULL),
155 ("Re-initialization of taskqueue callback?"));
156
157 queue->tq_callbacks[cb_type] = callback;
158 queue->tq_cb_contexts[cb_type] = context;
159 }
160
161 /*
162 * Signal a taskqueue thread to terminate.
163 */
164 static void
165 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
166 {
167
168 while (tq->tq_tcount > 0 || tq->tq_callouts > 0) {
169 wakeup(tq);
170 TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0);
171 }
172 }
173
174 void
175 taskqueue_free(struct taskqueue *queue)
176 {
177
178 TQ_LOCK(queue);
179 queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
180 taskqueue_terminate(queue->tq_threads, queue);
181 KASSERT(TAILQ_EMPTY(&queue->tq_active), ("Tasks still running?"));
182 KASSERT(queue->tq_callouts == 0, ("Armed timeout tasks"));
183 mtx_destroy(&queue->tq_mutex);
184 free(queue->tq_threads, M_TASKQUEUE);
185 free(queue, M_TASKQUEUE);
186 }
187
188 static int
189 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
190 {
191 struct task *ins;
192 struct task *prev;
193
194 /*
195 * Count multiple enqueues.
196 */
197 if (task->ta_pending) {
198 if (task->ta_pending < USHRT_MAX)
199 task->ta_pending++;
200 return (0);
201 }
202
203 /*
204 * Optimise the case when all tasks have the same priority.
205 */
206 prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
207 if (!prev || prev->ta_priority >= task->ta_priority) {
208 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
209 } else {
210 prev = NULL;
211 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
212 prev = ins, ins = STAILQ_NEXT(ins, ta_link))
213 if (ins->ta_priority < task->ta_priority)
214 break;
215
216 if (prev)
217 STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
218 else
219 STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
220 }
221
222 task->ta_pending = 1;
223 if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0)
224 queue->tq_enqueue(queue->tq_context);
225 else
226 queue->tq_flags |= TQ_FLAGS_PENDING;
227
228 return (0);
229 }
230 int
231 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
232 {
233 int res;
234
235 TQ_LOCK(queue);
236 res = taskqueue_enqueue_locked(queue, task);
237 TQ_UNLOCK(queue);
238
239 return (res);
240 }
241
242 static void
243 taskqueue_timeout_func(void *arg)
244 {
245 struct taskqueue *queue;
246 struct timeout_task *timeout_task;
247
248 timeout_task = arg;
249 queue = timeout_task->q;
250 KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
251 timeout_task->f &= ~DT_CALLOUT_ARMED;
252 queue->tq_callouts--;
253 taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
254 }
255
256 int
257 taskqueue_enqueue_timeout(struct taskqueue *queue,
258 struct timeout_task *timeout_task, int ticks)
259 {
260 int res;
261
262 TQ_LOCK(queue);
263 KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
264 ("Migrated queue"));
265 KASSERT(!queue->tq_spin, ("Timeout for spin-queue"));
266 timeout_task->q = queue;
267 res = timeout_task->t.ta_pending;
268 if (ticks == 0) {
269 taskqueue_enqueue_locked(queue, &timeout_task->t);
270 } else {
271 if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
272 res++;
273 } else {
274 queue->tq_callouts++;
275 timeout_task->f |= DT_CALLOUT_ARMED;
276 if (ticks < 0)
277 ticks = -ticks; /* Ignore overflow. */
278 }
279 if (ticks > 0) {
280 callout_reset(&timeout_task->c, ticks,
281 taskqueue_timeout_func, timeout_task);
282 }
283 }
284 TQ_UNLOCK(queue);
285 return (res);
286 }
287
288 static void
289 taskqueue_drain_running(struct taskqueue *queue)
290 {
291
292 while (!TAILQ_EMPTY(&queue->tq_active))
293 TQ_SLEEP(queue, &queue->tq_active, &queue->tq_mutex,
294 PWAIT, "-", 0);
295 }
296
297 void
298 taskqueue_block(struct taskqueue *queue)
299 {
300
301 TQ_LOCK(queue);
302 queue->tq_flags |= TQ_FLAGS_BLOCKED;
303 TQ_UNLOCK(queue);
304 }
305
306 void
307 taskqueue_unblock(struct taskqueue *queue)
308 {
309
310 TQ_LOCK(queue);
311 queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
312 if (queue->tq_flags & TQ_FLAGS_PENDING) {
313 queue->tq_flags &= ~TQ_FLAGS_PENDING;
314 queue->tq_enqueue(queue->tq_context);
315 }
316 TQ_UNLOCK(queue);
317 }
318
319 static void
320 taskqueue_run_locked(struct taskqueue *queue)
321 {
322 struct taskqueue_busy tb;
323 struct task *task;
324 int pending;
325
326 TQ_ASSERT_LOCKED(queue);
327 tb.tb_running = NULL;
328 TAILQ_INSERT_TAIL(&queue->tq_active, &tb, tb_link);
329
330 while (STAILQ_FIRST(&queue->tq_queue)) {
331 /*
332 * Carefully remove the first task from the queue and
333 * zero its pending count.
334 */
335 task = STAILQ_FIRST(&queue->tq_queue);
336 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
337 pending = task->ta_pending;
338 task->ta_pending = 0;
339 tb.tb_running = task;
340 TQ_UNLOCK(queue);
341
342 task->ta_func(task->ta_context, pending);
343
344 TQ_LOCK(queue);
345 tb.tb_running = NULL;
346 wakeup(task);
347 }
348 TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
349 if (TAILQ_EMPTY(&queue->tq_active))
350 wakeup(&queue->tq_active);
351 }
352
353 void
354 taskqueue_run(struct taskqueue *queue)
355 {
356
357 TQ_LOCK(queue);
358 taskqueue_run_locked(queue);
359 TQ_UNLOCK(queue);
360 }
361
362 static int
363 task_is_running(struct taskqueue *queue, struct task *task)
364 {
365 struct taskqueue_busy *tb;
366
367 TQ_ASSERT_LOCKED(queue);
368 TAILQ_FOREACH(tb, &queue->tq_active, tb_link) {
369 if (tb->tb_running == task)
370 return (1);
371 }
372 return (0);
373 }
374
375 static int
376 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
377 u_int *pendp)
378 {
379
380 if (task->ta_pending > 0)
381 STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
382 if (pendp != NULL)
383 *pendp = task->ta_pending;
384 task->ta_pending = 0;
385 return (task_is_running(queue, task) ? EBUSY : 0);
386 }
387
388 int
389 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
390 {
391 int error;
392
393 TQ_LOCK(queue);
394 error = taskqueue_cancel_locked(queue, task, pendp);
395 TQ_UNLOCK(queue);
396
397 return (error);
398 }
399
400 int
401 taskqueue_cancel_timeout(struct taskqueue *queue,
402 struct timeout_task *timeout_task, u_int *pendp)
403 {
404 u_int pending, pending1;
405 int error;
406
407 TQ_LOCK(queue);
408 pending = !!callout_stop(&timeout_task->c);
409 error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
410 if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
411 timeout_task->f &= ~DT_CALLOUT_ARMED;
412 queue->tq_callouts--;
413 }
414 TQ_UNLOCK(queue);
415
416 if (pendp != NULL)
417 *pendp = pending + pending1;
418 return (error);
419 }
420
421 void
422 taskqueue_drain(struct taskqueue *queue, struct task *task)
423 {
424
425 if (!queue->tq_spin)
426 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
427
428 TQ_LOCK(queue);
429 while (task->ta_pending != 0 || task_is_running(queue, task))
430 TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
431 TQ_UNLOCK(queue);
432 }
433
434 void
435 taskqueue_drain_all(struct taskqueue *queue)
436 {
437 struct task *task;
438
439 if (!queue->tq_spin)
440 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
441
442 TQ_LOCK(queue);
443 task = STAILQ_LAST(&queue->tq_queue, task, ta_link);
444 if (task != NULL)
445 while (task->ta_pending != 0)
446 TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
447 taskqueue_drain_running(queue);
448 KASSERT(STAILQ_EMPTY(&queue->tq_queue),
449 ("taskqueue queue is not empty after draining"));
450 TQ_UNLOCK(queue);
451 }
452
453 void
454 taskqueue_drain_timeout(struct taskqueue *queue,
455 struct timeout_task *timeout_task)
456 {
457
458 callout_drain(&timeout_task->c);
459 taskqueue_drain(queue, &timeout_task->t);
460 }
461
462 static void
463 taskqueue_swi_enqueue(void *context)
464 {
465 swi_sched(taskqueue_ih, 0);
466 }
467
468 static void
469 taskqueue_swi_run(void *dummy)
470 {
471 taskqueue_run(taskqueue_swi);
472 }
473
474 static void
475 taskqueue_swi_giant_enqueue(void *context)
476 {
477 swi_sched(taskqueue_giant_ih, 0);
478 }
479
480 static void
481 taskqueue_swi_giant_run(void *dummy)
482 {
483 taskqueue_run(taskqueue_swi_giant);
484 }
485
486 int
487 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
488 const char *name, ...)
489 {
490 va_list ap;
491 struct thread *td;
492 struct taskqueue *tq;
493 int i, error;
494 char ktname[MAXCOMLEN + 1];
495
496 if (count <= 0)
497 return (EINVAL);
498
499 tq = *tqp;
500
501 va_start(ap, name);
502 vsnprintf(ktname, sizeof(ktname), name, ap);
503 va_end(ap);
504
505 tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
506 M_NOWAIT | M_ZERO);
507 if (tq->tq_threads == NULL) {
508 printf("%s: no memory for %s threads\n", __func__, ktname);
509 return (ENOMEM);
510 }
511
512 for (i = 0; i < count; i++) {
513 if (count == 1)
514 error = kthread_add(taskqueue_thread_loop, tqp, NULL,
515 &tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname);
516 else
517 error = kthread_add(taskqueue_thread_loop, tqp, NULL,
518 &tq->tq_threads[i], RFSTOPPED, 0,
519 "%s_%d", ktname, i);
520 if (error) {
521 /* should be ok to continue, taskqueue_free will dtrt */
522 printf("%s: kthread_add(%s): error %d", __func__,
523 ktname, error);
524 tq->tq_threads[i] = NULL; /* paranoid */
525 } else
526 tq->tq_tcount++;
527 }
528 for (i = 0; i < count; i++) {
529 if (tq->tq_threads[i] == NULL)
530 continue;
531 td = tq->tq_threads[i];
532 thread_lock(td);
533 sched_prio(td, pri);
534 sched_add(td, SRQ_BORING);
535 thread_unlock(td);
536 }
537
538 return (0);
539 }
540
541 static inline void
542 taskqueue_run_callback(struct taskqueue *tq,
543 enum taskqueue_callback_type cb_type)
544 {
545 taskqueue_callback_fn tq_callback;
546
547 TQ_ASSERT_UNLOCKED(tq);
548 tq_callback = tq->tq_callbacks[cb_type];
549 if (tq_callback != NULL)
550 tq_callback(tq->tq_cb_contexts[cb_type]);
551 }
552
553 void
554 taskqueue_thread_loop(void *arg)
555 {
556 struct taskqueue **tqp, *tq;
557
558 tqp = arg;
559 tq = *tqp;
560 taskqueue_run_callback(tq, TASKQUEUE_CALLBACK_TYPE_INIT);
561 TQ_LOCK(tq);
562 while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
563 taskqueue_run_locked(tq);
564 /*
565 * Because taskqueue_run() can drop tq_mutex, we need to
566 * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
567 * meantime, which means we missed a wakeup.
568 */
569 if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
570 break;
571 TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
572 }
573 taskqueue_run_locked(tq);
574
575 /*
576 * This thread is on its way out, so just drop the lock temporarily
577 * in order to call the shutdown callback. This allows the callback
578 * to look at the taskqueue, even just before it dies.
579 */
580 TQ_UNLOCK(tq);
581 taskqueue_run_callback(tq, TASKQUEUE_CALLBACK_TYPE_SHUTDOWN);
582 TQ_LOCK(tq);
583
584 /* rendezvous with thread that asked us to terminate */
585 tq->tq_tcount--;
586 wakeup_one(tq->tq_threads);
587 TQ_UNLOCK(tq);
588 kthread_exit();
589 }
590
591 void
592 taskqueue_thread_enqueue(void *context)
593 {
594 struct taskqueue **tqp, *tq;
595
596 tqp = context;
597 tq = *tqp;
598
599 TQ_ASSERT_LOCKED(tq);
600 wakeup_one(tq);
601 }
602
603 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
604 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
605 INTR_MPSAFE, &taskqueue_ih));
606
607 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
608 swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
609 NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
610
611 TASKQUEUE_DEFINE_THREAD(thread);
612
613 struct taskqueue *
614 taskqueue_create_fast(const char *name, int mflags,
615 taskqueue_enqueue_fn enqueue, void *context)
616 {
617 return _taskqueue_create(name, mflags, enqueue, context,
618 MTX_SPIN, "fast_taskqueue");
619 }
620
621 /* NB: for backwards compatibility */
622 int
623 taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
624 {
625 return taskqueue_enqueue(queue, task);
626 }
627
628 static void *taskqueue_fast_ih;
629
630 static void
631 taskqueue_fast_enqueue(void *context)
632 {
633 swi_sched(taskqueue_fast_ih, 0);
634 }
635
636 static void
637 taskqueue_fast_run(void *dummy)
638 {
639 taskqueue_run(taskqueue_fast);
640 }
641
642 TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
643 swi_add(NULL, "fast taskq", taskqueue_fast_run, NULL,
644 SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
645
646 int
647 taskqueue_member(struct taskqueue *queue, struct thread *td)
648 {
649 int i, j, ret = 0;
650
651 for (i = 0, j = 0; ; i++) {
652 if (queue->tq_threads[i] == NULL)
653 continue;
654 if (queue->tq_threads[i] == td) {
655 ret = 1;
656 break;
657 }
658 if (++j >= queue->tq_tcount)
659 break;
660 }
661 return (ret);
662 }
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