xref: /freebsd/sys/kern/subr_taskqueue.c (revision cc16dea626cf2fc80cde667ac4798065108e596c) 
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("$FreeBSD$");
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 void
289 taskqueue_block(struct taskqueue *queue)
290 {
291 
292 	TQ_LOCK(queue);
293 	queue->tq_flags |= TQ_FLAGS_BLOCKED;
294 	TQ_UNLOCK(queue);
295 }
296 
297 void
298 taskqueue_unblock(struct taskqueue *queue)
299 {
300 
301 	TQ_LOCK(queue);
302 	queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
303 	if (queue->tq_flags & TQ_FLAGS_PENDING) {
304 		queue->tq_flags &= ~TQ_FLAGS_PENDING;
305 		queue->tq_enqueue(queue->tq_context);
306 	}
307 	TQ_UNLOCK(queue);
308 }
309 
310 static void
311 taskqueue_run_locked(struct taskqueue *queue)
312 {
313 	struct taskqueue_busy tb;
314 	struct task *task;
315 	int pending;
316 
317 	TQ_ASSERT_LOCKED(queue);
318 	tb.tb_running = NULL;
319 	TAILQ_INSERT_TAIL(&queue->tq_active, &tb, tb_link);
320 
321 	while (STAILQ_FIRST(&queue->tq_queue)) {
322 		/*
323 		 * Carefully remove the first task from the queue and
324 		 * zero its pending count.
325 		 */
326 		task = STAILQ_FIRST(&queue->tq_queue);
327 		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
328 		pending = task->ta_pending;
329 		task->ta_pending = 0;
330 		tb.tb_running = task;
331 		TQ_UNLOCK(queue);
332 
333 		task->ta_func(task->ta_context, pending);
334 
335 		TQ_LOCK(queue);
336 		tb.tb_running = NULL;
337 		wakeup(task);
338 	}
339 	TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
340 }
341 
342 void
343 taskqueue_run(struct taskqueue *queue)
344 {
345 
346 	TQ_LOCK(queue);
347 	taskqueue_run_locked(queue);
348 	TQ_UNLOCK(queue);
349 }
350 
351 static int
352 task_is_running(struct taskqueue *queue, struct task *task)
353 {
354 	struct taskqueue_busy *tb;
355 
356 	TQ_ASSERT_LOCKED(queue);
357 	TAILQ_FOREACH(tb, &queue->tq_active, tb_link) {
358 		if (tb->tb_running == task)
359 			return (1);
360 	}
361 	return (0);
362 }
363 
364 static int
365 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
366     u_int *pendp)
367 {
368 
369 	if (task->ta_pending > 0)
370 		STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
371 	if (pendp != NULL)
372 		*pendp = task->ta_pending;
373 	task->ta_pending = 0;
374 	return (task_is_running(queue, task) ? EBUSY : 0);
375 }
376 
377 int
378 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
379 {
380 	u_int pending;
381 	int error;
382 
383 	TQ_LOCK(queue);
384 	pending = task->ta_pending;
385 	error = taskqueue_cancel_locked(queue, task, pendp);
386 	TQ_UNLOCK(queue);
387 
388 	return (error);
389 }
390 
391 int
392 taskqueue_cancel_timeout(struct taskqueue *queue,
393     struct timeout_task *timeout_task, u_int *pendp)
394 {
395 	u_int pending, pending1;
396 	int error;
397 
398 	TQ_LOCK(queue);
399 	pending = !!callout_stop(&timeout_task->c);
400 	error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
401 	if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
402 		timeout_task->f &= ~DT_CALLOUT_ARMED;
403 		queue->tq_callouts--;
404 	}
405 	TQ_UNLOCK(queue);
406 
407 	if (pendp != NULL)
408 		*pendp = pending + pending1;
409 	return (error);
410 }
411 
412 void
413 taskqueue_drain(struct taskqueue *queue, struct task *task)
414 {
415 
416 	if (!queue->tq_spin)
417 		WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
418 
419 	TQ_LOCK(queue);
420 	while (task->ta_pending != 0 || task_is_running(queue, task))
421 		TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
422 	TQ_UNLOCK(queue);
423 }
424 
425 void
426 taskqueue_drain_timeout(struct taskqueue *queue,
427     struct timeout_task *timeout_task)
428 {
429 
430 	callout_drain(&timeout_task->c);
431 	taskqueue_drain(queue, &timeout_task->t);
432 }
433 
434 static void
435 taskqueue_swi_enqueue(void *context)
436 {
437 	swi_sched(taskqueue_ih, 0);
438 }
439 
440 static void
441 taskqueue_swi_run(void *dummy)
442 {
443 	taskqueue_run(taskqueue_swi);
444 }
445 
446 static void
447 taskqueue_swi_giant_enqueue(void *context)
448 {
449 	swi_sched(taskqueue_giant_ih, 0);
450 }
451 
452 static void
453 taskqueue_swi_giant_run(void *dummy)
454 {
455 	taskqueue_run(taskqueue_swi_giant);
456 }
457 
458 int
459 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
460 			const char *name, ...)
461 {
462 	va_list ap;
463 	struct thread *td;
464 	struct taskqueue *tq;
465 	int i, error;
466 	char ktname[MAXCOMLEN + 1];
467 
468 	if (count <= 0)
469 		return (EINVAL);
470 
471 	tq = *tqp;
472 
473 	va_start(ap, name);
474 	vsnprintf(ktname, sizeof(ktname), name, ap);
475 	va_end(ap);
476 
477 	tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
478 	    M_NOWAIT | M_ZERO);
479 	if (tq->tq_threads == NULL) {
480 		printf("%s: no memory for %s threads\n", __func__, ktname);
481 		return (ENOMEM);
482 	}
483 
484 	for (i = 0; i < count; i++) {
485 		if (count == 1)
486 			error = kthread_add(taskqueue_thread_loop, tqp, NULL,
487 			    &tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname);
488 		else
489 			error = kthread_add(taskqueue_thread_loop, tqp, NULL,
490 			    &tq->tq_threads[i], RFSTOPPED, 0,
491 			    "%s_%d", ktname, i);
492 		if (error) {
493 			/* should be ok to continue, taskqueue_free will dtrt */
494 			printf("%s: kthread_add(%s): error %d", __func__,
495 			    ktname, error);
496 			tq->tq_threads[i] = NULL;		/* paranoid */
497 		} else
498 			tq->tq_tcount++;
499 	}
500 	for (i = 0; i < count; i++) {
501 		if (tq->tq_threads[i] == NULL)
502 			continue;
503 		td = tq->tq_threads[i];
504 		thread_lock(td);
505 		sched_prio(td, pri);
506 		sched_add(td, SRQ_BORING);
507 		thread_unlock(td);
508 	}
509 
510 	return (0);
511 }
512 
513 static inline void
514 taskqueue_run_callback(struct taskqueue *tq,
515     enum taskqueue_callback_type cb_type)
516 {
517 	taskqueue_callback_fn tq_callback;
518 
519 	TQ_ASSERT_UNLOCKED(tq);
520 	tq_callback = tq->tq_callbacks[cb_type];
521 	if (tq_callback != NULL)
522 		tq_callback(tq->tq_cb_contexts[cb_type]);
523 }
524 
525 void
526 taskqueue_thread_loop(void *arg)
527 {
528 	struct taskqueue **tqp, *tq;
529 
530 	tqp = arg;
531 	tq = *tqp;
532 	taskqueue_run_callback(tq, TASKQUEUE_CALLBACK_TYPE_INIT);
533 	TQ_LOCK(tq);
534 	while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
535 		taskqueue_run_locked(tq);
536 		/*
537 		 * Because taskqueue_run() can drop tq_mutex, we need to
538 		 * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
539 		 * meantime, which means we missed a wakeup.
540 		 */
541 		if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
542 			break;
543 		TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
544 	}
545 	taskqueue_run_locked(tq);
546 
547 	/*
548 	 * This thread is on its way out, so just drop the lock temporarily
549 	 * in order to call the shutdown callback.  This allows the callback
550 	 * to look at the taskqueue, even just before it dies.
551 	 */
552 	TQ_UNLOCK(tq);
553 	taskqueue_run_callback(tq, TASKQUEUE_CALLBACK_TYPE_SHUTDOWN);
554 	TQ_LOCK(tq);
555 
556 	/* rendezvous with thread that asked us to terminate */
557 	tq->tq_tcount--;
558 	wakeup_one(tq->tq_threads);
559 	TQ_UNLOCK(tq);
560 	kthread_exit();
561 }
562 
563 void
564 taskqueue_thread_enqueue(void *context)
565 {
566 	struct taskqueue **tqp, *tq;
567 
568 	tqp = context;
569 	tq = *tqp;
570 
571 	TQ_ASSERT_LOCKED(tq);
572 	wakeup_one(tq);
573 }
574 
575 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
576 		 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
577 		     INTR_MPSAFE, &taskqueue_ih));
578 
579 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
580 		 swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
581 		     NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
582 
583 TASKQUEUE_DEFINE_THREAD(thread);
584 
585 struct taskqueue *
586 taskqueue_create_fast(const char *name, int mflags,
587 		 taskqueue_enqueue_fn enqueue, void *context)
588 {
589 	return _taskqueue_create(name, mflags, enqueue, context,
590 			MTX_SPIN, "fast_taskqueue");
591 }
592 
593 /* NB: for backwards compatibility */
594 int
595 taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
596 {
597 	return taskqueue_enqueue(queue, task);
598 }
599 
600 static void	*taskqueue_fast_ih;
601 
602 static void
603 taskqueue_fast_enqueue(void *context)
604 {
605 	swi_sched(taskqueue_fast_ih, 0);
606 }
607 
608 static void
609 taskqueue_fast_run(void *dummy)
610 {
611 	taskqueue_run(taskqueue_fast);
612 }
613 
614 TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
615 	swi_add(NULL, "fast taskq", taskqueue_fast_run, NULL,
616 	SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
617 
618 int
619 taskqueue_member(struct taskqueue *queue, struct thread *td)
620 {
621 	int i, j, ret = 0;
622 
623 	TQ_LOCK(queue);
624 	for (i = 0, j = 0; ; i++) {
625 		if (queue->tq_threads[i] == NULL)
626 			continue;
627 		if (queue->tq_threads[i] == td) {
628 			ret = 1;
629 			break;
630 		}
631 		if (++j >= queue->tq_tcount)
632 			break;
633 	}
634 	TQ_UNLOCK(queue);
635 	return (ret);
636 }
637