xref: /freebsd/sys/kern/subr_taskqueue.c (revision 6f9c8e5b074419423648ffb89b83fd2f257e90b7)
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/lock.h>
37 #include <sys/malloc.h>
38 #include <sys/mutex.h>
39 #include <sys/proc.h>
40 #include <sys/sched.h>
41 #include <sys/taskqueue.h>
42 #include <sys/unistd.h>
43 #include <machine/stdarg.h>
44 
45 static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
46 static void	*taskqueue_giant_ih;
47 static void	*taskqueue_ih;
48 
49 struct taskqueue_busy {
50 	struct task	*tb_running;
51 	TAILQ_ENTRY(taskqueue_busy) tb_link;
52 };
53 
54 struct taskqueue {
55 	STAILQ_HEAD(, task)	tq_queue;
56 	taskqueue_enqueue_fn	tq_enqueue;
57 	void			*tq_context;
58 	TAILQ_HEAD(, taskqueue_busy) tq_active;
59 	struct mtx		tq_mutex;
60 	struct thread		**tq_threads;
61 	int			tq_tcount;
62 	int			tq_spin;
63 	int			tq_flags;
64 	int			tq_callouts;
65 };
66 
67 #define	TQ_FLAGS_ACTIVE		(1 << 0)
68 #define	TQ_FLAGS_BLOCKED	(1 << 1)
69 #define	TQ_FLAGS_PENDING	(1 << 2)
70 
71 #define	DT_CALLOUT_ARMED	(1 << 0)
72 
73 #define	TQ_LOCK(tq)							\
74 	do {								\
75 		if ((tq)->tq_spin)					\
76 			mtx_lock_spin(&(tq)->tq_mutex);			\
77 		else							\
78 			mtx_lock(&(tq)->tq_mutex);			\
79 	} while (0)
80 
81 #define	TQ_UNLOCK(tq)							\
82 	do {								\
83 		if ((tq)->tq_spin)					\
84 			mtx_unlock_spin(&(tq)->tq_mutex);		\
85 		else							\
86 			mtx_unlock(&(tq)->tq_mutex);			\
87 	} while (0)
88 
89 void
90 _timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
91     int priority, task_fn_t func, void *context)
92 {
93 
94 	TASK_INIT(&timeout_task->t, priority, func, context);
95 	callout_init_mtx(&timeout_task->c, &queue->tq_mutex, 0);
96 	timeout_task->q = queue;
97 	timeout_task->f = 0;
98 }
99 
100 static __inline int
101 TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm,
102     int t)
103 {
104 	if (tq->tq_spin)
105 		return (msleep_spin(p, m, wm, t));
106 	return (msleep(p, m, pri, wm, t));
107 }
108 
109 static struct taskqueue *
110 _taskqueue_create(const char *name __unused, int mflags,
111 		 taskqueue_enqueue_fn enqueue, void *context,
112 		 int mtxflags, const char *mtxname)
113 {
114 	struct taskqueue *queue;
115 
116 	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
117 	if (!queue)
118 		return NULL;
119 
120 	STAILQ_INIT(&queue->tq_queue);
121 	TAILQ_INIT(&queue->tq_active);
122 	queue->tq_enqueue = enqueue;
123 	queue->tq_context = context;
124 	queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
125 	queue->tq_flags |= TQ_FLAGS_ACTIVE;
126 	mtx_init(&queue->tq_mutex, mtxname, NULL, mtxflags);
127 
128 	return queue;
129 }
130 
131 struct taskqueue *
132 taskqueue_create(const char *name, int mflags,
133 		 taskqueue_enqueue_fn enqueue, void *context)
134 {
135 	return _taskqueue_create(name, mflags, enqueue, context,
136 			MTX_DEF, "taskqueue");
137 }
138 
139 /*
140  * Signal a taskqueue thread to terminate.
141  */
142 static void
143 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
144 {
145 
146 	while (tq->tq_tcount > 0 || tq->tq_callouts > 0) {
147 		wakeup(tq);
148 		TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0);
149 	}
150 }
151 
152 void
153 taskqueue_free(struct taskqueue *queue)
154 {
155 
156 	TQ_LOCK(queue);
157 	queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
158 	taskqueue_terminate(queue->tq_threads, queue);
159 	KASSERT(TAILQ_EMPTY(&queue->tq_active), ("Tasks still running?"));
160 	KASSERT(queue->tq_callouts == 0, ("Armed timeout tasks"));
161 	mtx_destroy(&queue->tq_mutex);
162 	free(queue->tq_threads, M_TASKQUEUE);
163 	free(queue, M_TASKQUEUE);
164 }
165 
166 static int
167 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
168 {
169 	struct task *ins;
170 	struct task *prev;
171 
172 	/*
173 	 * Count multiple enqueues.
174 	 */
175 	if (task->ta_pending) {
176 		task->ta_pending++;
177 		return (0);
178 	}
179 
180 	/*
181 	 * Optimise the case when all tasks have the same priority.
182 	 */
183 	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
184 	if (!prev || prev->ta_priority >= task->ta_priority) {
185 		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
186 	} else {
187 		prev = NULL;
188 		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
189 		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
190 			if (ins->ta_priority < task->ta_priority)
191 				break;
192 
193 		if (prev)
194 			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
195 		else
196 			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
197 	}
198 
199 	task->ta_pending = 1;
200 	if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0)
201 		queue->tq_enqueue(queue->tq_context);
202 	else
203 		queue->tq_flags |= TQ_FLAGS_PENDING;
204 
205 	return (0);
206 }
207 int
208 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
209 {
210 	int res;
211 
212 	TQ_LOCK(queue);
213 	res = taskqueue_enqueue_locked(queue, task);
214 	TQ_UNLOCK(queue);
215 
216 	return (res);
217 }
218 
219 static void
220 taskqueue_timeout_func(void *arg)
221 {
222 	struct taskqueue *queue;
223 	struct timeout_task *timeout_task;
224 
225 	timeout_task = arg;
226 	queue = timeout_task->q;
227 	KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
228 	timeout_task->f &= ~DT_CALLOUT_ARMED;
229 	queue->tq_callouts--;
230 	taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
231 }
232 
233 int
234 taskqueue_enqueue_timeout(struct taskqueue *queue,
235     struct timeout_task *timeout_task, int ticks)
236 {
237 	int res;
238 
239 	TQ_LOCK(queue);
240 	KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
241 	    ("Migrated queue"));
242 	KASSERT(!queue->tq_spin, ("Timeout for spin-queue"));
243 	timeout_task->q = queue;
244 	res = timeout_task->t.ta_pending;
245 	if (ticks == 0) {
246 		taskqueue_enqueue_locked(queue, &timeout_task->t);
247 	} else {
248 		if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
249 			res++;
250 		} else {
251 			queue->tq_callouts++;
252 			timeout_task->f |= DT_CALLOUT_ARMED;
253 		}
254 		callout_reset(&timeout_task->c, ticks, taskqueue_timeout_func,
255 		    timeout_task);
256 	}
257 	TQ_UNLOCK(queue);
258 	return (res);
259 }
260 
261 void
262 taskqueue_block(struct taskqueue *queue)
263 {
264 
265 	TQ_LOCK(queue);
266 	queue->tq_flags |= TQ_FLAGS_BLOCKED;
267 	TQ_UNLOCK(queue);
268 }
269 
270 void
271 taskqueue_unblock(struct taskqueue *queue)
272 {
273 
274 	TQ_LOCK(queue);
275 	queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
276 	if (queue->tq_flags & TQ_FLAGS_PENDING) {
277 		queue->tq_flags &= ~TQ_FLAGS_PENDING;
278 		queue->tq_enqueue(queue->tq_context);
279 	}
280 	TQ_UNLOCK(queue);
281 }
282 
283 static void
284 taskqueue_run_locked(struct taskqueue *queue)
285 {
286 	struct taskqueue_busy tb;
287 	struct task *task;
288 	int pending;
289 
290 	mtx_assert(&queue->tq_mutex, MA_OWNED);
291 	tb.tb_running = NULL;
292 	TAILQ_INSERT_TAIL(&queue->tq_active, &tb, tb_link);
293 
294 	while (STAILQ_FIRST(&queue->tq_queue)) {
295 		/*
296 		 * Carefully remove the first task from the queue and
297 		 * zero its pending count.
298 		 */
299 		task = STAILQ_FIRST(&queue->tq_queue);
300 		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
301 		pending = task->ta_pending;
302 		task->ta_pending = 0;
303 		tb.tb_running = task;
304 		TQ_UNLOCK(queue);
305 
306 		task->ta_func(task->ta_context, pending);
307 
308 		TQ_LOCK(queue);
309 		tb.tb_running = NULL;
310 		wakeup(task);
311 	}
312 	TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
313 }
314 
315 void
316 taskqueue_run(struct taskqueue *queue)
317 {
318 
319 	TQ_LOCK(queue);
320 	taskqueue_run_locked(queue);
321 	TQ_UNLOCK(queue);
322 }
323 
324 static int
325 task_is_running(struct taskqueue *queue, struct task *task)
326 {
327 	struct taskqueue_busy *tb;
328 
329 	mtx_assert(&queue->tq_mutex, MA_OWNED);
330 	TAILQ_FOREACH(tb, &queue->tq_active, tb_link) {
331 		if (tb->tb_running == task)
332 			return (1);
333 	}
334 	return (0);
335 }
336 
337 static int
338 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
339     u_int *pendp)
340 {
341 
342 	if (task->ta_pending > 0)
343 		STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
344 	if (pendp != NULL)
345 		*pendp = task->ta_pending;
346 	task->ta_pending = 0;
347 	return (task_is_running(queue, task) ? EBUSY : 0);
348 }
349 
350 int
351 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
352 {
353 	u_int pending;
354 	int error;
355 
356 	TQ_LOCK(queue);
357 	pending = task->ta_pending;
358 	error = taskqueue_cancel_locked(queue, task, pendp);
359 	TQ_UNLOCK(queue);
360 
361 	return (error);
362 }
363 
364 int
365 taskqueue_cancel_timeout(struct taskqueue *queue,
366     struct timeout_task *timeout_task, u_int *pendp)
367 {
368 	u_int pending, pending1;
369 	int error;
370 
371 	TQ_LOCK(queue);
372 	pending = !!callout_stop(&timeout_task->c);
373 	error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
374 	if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
375 		timeout_task->f &= ~DT_CALLOUT_ARMED;
376 		queue->tq_callouts--;
377 	}
378 	TQ_UNLOCK(queue);
379 
380 	if (pendp != NULL)
381 		*pendp = pending + pending1;
382 	return (error);
383 }
384 
385 void
386 taskqueue_drain(struct taskqueue *queue, struct task *task)
387 {
388 
389 	if (!queue->tq_spin)
390 		WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
391 
392 	TQ_LOCK(queue);
393 	while (task->ta_pending != 0 || task_is_running(queue, task))
394 		TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
395 	TQ_UNLOCK(queue);
396 }
397 
398 void
399 taskqueue_drain_timeout(struct taskqueue *queue,
400     struct timeout_task *timeout_task)
401 {
402 
403 	callout_drain(&timeout_task->c);
404 	taskqueue_drain(queue, &timeout_task->t);
405 }
406 
407 static void
408 taskqueue_swi_enqueue(void *context)
409 {
410 	swi_sched(taskqueue_ih, 0);
411 }
412 
413 static void
414 taskqueue_swi_run(void *dummy)
415 {
416 	taskqueue_run(taskqueue_swi);
417 }
418 
419 static void
420 taskqueue_swi_giant_enqueue(void *context)
421 {
422 	swi_sched(taskqueue_giant_ih, 0);
423 }
424 
425 static void
426 taskqueue_swi_giant_run(void *dummy)
427 {
428 	taskqueue_run(taskqueue_swi_giant);
429 }
430 
431 int
432 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
433 			const char *name, ...)
434 {
435 	va_list ap;
436 	struct thread *td;
437 	struct taskqueue *tq;
438 	int i, error;
439 	char ktname[MAXCOMLEN + 1];
440 
441 	if (count <= 0)
442 		return (EINVAL);
443 
444 	tq = *tqp;
445 
446 	va_start(ap, name);
447 	vsnprintf(ktname, sizeof(ktname), name, ap);
448 	va_end(ap);
449 
450 	tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
451 	    M_NOWAIT | M_ZERO);
452 	if (tq->tq_threads == NULL) {
453 		printf("%s: no memory for %s threads\n", __func__, ktname);
454 		return (ENOMEM);
455 	}
456 
457 	for (i = 0; i < count; i++) {
458 		if (count == 1)
459 			error = kthread_add(taskqueue_thread_loop, tqp, NULL,
460 			    &tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname);
461 		else
462 			error = kthread_add(taskqueue_thread_loop, tqp, NULL,
463 			    &tq->tq_threads[i], RFSTOPPED, 0,
464 			    "%s_%d", ktname, i);
465 		if (error) {
466 			/* should be ok to continue, taskqueue_free will dtrt */
467 			printf("%s: kthread_add(%s): error %d", __func__,
468 			    ktname, error);
469 			tq->tq_threads[i] = NULL;		/* paranoid */
470 		} else
471 			tq->tq_tcount++;
472 	}
473 	for (i = 0; i < count; i++) {
474 		if (tq->tq_threads[i] == NULL)
475 			continue;
476 		td = tq->tq_threads[i];
477 		thread_lock(td);
478 		sched_prio(td, pri);
479 		sched_add(td, SRQ_BORING);
480 		thread_unlock(td);
481 	}
482 
483 	return (0);
484 }
485 
486 void
487 taskqueue_thread_loop(void *arg)
488 {
489 	struct taskqueue **tqp, *tq;
490 
491 	tqp = arg;
492 	tq = *tqp;
493 	TQ_LOCK(tq);
494 	while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
495 		taskqueue_run_locked(tq);
496 		/*
497 		 * Because taskqueue_run() can drop tq_mutex, we need to
498 		 * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
499 		 * meantime, which means we missed a wakeup.
500 		 */
501 		if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
502 			break;
503 		TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
504 	}
505 	taskqueue_run_locked(tq);
506 
507 	/* rendezvous with thread that asked us to terminate */
508 	tq->tq_tcount--;
509 	wakeup_one(tq->tq_threads);
510 	TQ_UNLOCK(tq);
511 	kthread_exit();
512 }
513 
514 void
515 taskqueue_thread_enqueue(void *context)
516 {
517 	struct taskqueue **tqp, *tq;
518 
519 	tqp = context;
520 	tq = *tqp;
521 
522 	mtx_assert(&tq->tq_mutex, MA_OWNED);
523 	wakeup_one(tq);
524 }
525 
526 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
527 		 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
528 		     INTR_MPSAFE, &taskqueue_ih));
529 
530 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
531 		 swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
532 		     NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
533 
534 TASKQUEUE_DEFINE_THREAD(thread);
535 
536 struct taskqueue *
537 taskqueue_create_fast(const char *name, int mflags,
538 		 taskqueue_enqueue_fn enqueue, void *context)
539 {
540 	return _taskqueue_create(name, mflags, enqueue, context,
541 			MTX_SPIN, "fast_taskqueue");
542 }
543 
544 /* NB: for backwards compatibility */
545 int
546 taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
547 {
548 	return taskqueue_enqueue(queue, task);
549 }
550 
551 static void	*taskqueue_fast_ih;
552 
553 static void
554 taskqueue_fast_enqueue(void *context)
555 {
556 	swi_sched(taskqueue_fast_ih, 0);
557 }
558 
559 static void
560 taskqueue_fast_run(void *dummy)
561 {
562 	taskqueue_run(taskqueue_fast);
563 }
564 
565 TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
566 	swi_add(NULL, "Fast task queue", taskqueue_fast_run, NULL,
567 	SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
568 
569 int
570 taskqueue_member(struct taskqueue *queue, struct thread *td)
571 {
572 	int i, j, ret = 0;
573 
574 	TQ_LOCK(queue);
575 	for (i = 0, j = 0; ; i++) {
576 		if (queue->tq_threads[i] == NULL)
577 			continue;
578 		if (queue->tq_threads[i] == td) {
579 			ret = 1;
580 			break;
581 		}
582 		if (++j >= queue->tq_tcount)
583 			break;
584 	}
585 	TQ_UNLOCK(queue);
586 	return (ret);
587 }
588