subr_taskqueue.c revision 243341 
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: head/sys/kern/subr_taskqueue.c 243341 2012-11-20 15:33:48Z kib $");
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
46static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
47static void	*taskqueue_giant_ih;
48static void	*taskqueue_ih;
49
50struct taskqueue_busy {
51	struct task	*tb_running;
52	TAILQ_ENTRY(taskqueue_busy) tb_link;
53};
54
55struct 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};
67
68#define	TQ_FLAGS_ACTIVE		(1 << 0)
69#define	TQ_FLAGS_BLOCKED	(1 << 1)
70#define	TQ_FLAGS_PENDING	(1 << 2)
71
72#define	DT_CALLOUT_ARMED	(1 << 0)
73
74#define	TQ_LOCK(tq)							\
75	do {								\
76		if ((tq)->tq_spin)					\
77			mtx_lock_spin(&(tq)->tq_mutex);			\
78		else							\
79			mtx_lock(&(tq)->tq_mutex);			\
80	} while (0)
81
82#define	TQ_UNLOCK(tq)							\
83	do {								\
84		if ((tq)->tq_spin)					\
85			mtx_unlock_spin(&(tq)->tq_mutex);		\
86		else							\
87			mtx_unlock(&(tq)->tq_mutex);			\
88	} while (0)
89
90void
91_timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
92    int priority, task_fn_t func, void *context)
93{
94
95	TASK_INIT(&timeout_task->t, priority, func, context);
96	callout_init_mtx(&timeout_task->c, &queue->tq_mutex, 0);
97	timeout_task->q = queue;
98	timeout_task->f = 0;
99}
100
101static __inline int
102TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm,
103    int t)
104{
105	if (tq->tq_spin)
106		return (msleep_spin(p, m, wm, t));
107	return (msleep(p, m, pri, wm, t));
108}
109
110static struct taskqueue *
111_taskqueue_create(const char *name __unused, int mflags,
112		 taskqueue_enqueue_fn enqueue, void *context,
113		 int mtxflags, const char *mtxname)
114{
115	struct taskqueue *queue;
116
117	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
118	if (!queue)
119		return NULL;
120
121	STAILQ_INIT(&queue->tq_queue);
122	TAILQ_INIT(&queue->tq_active);
123	queue->tq_enqueue = enqueue;
124	queue->tq_context = context;
125	queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
126	queue->tq_flags |= TQ_FLAGS_ACTIVE;
127	mtx_init(&queue->tq_mutex, mtxname, NULL, mtxflags);
128
129	return queue;
130}
131
132struct taskqueue *
133taskqueue_create(const char *name, int mflags,
134		 taskqueue_enqueue_fn enqueue, void *context)
135{
136	return _taskqueue_create(name, mflags, enqueue, context,
137			MTX_DEF, "taskqueue");
138}
139
140/*
141 * Signal a taskqueue thread to terminate.
142 */
143static void
144taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
145{
146
147	while (tq->tq_tcount > 0 || tq->tq_callouts > 0) {
148		wakeup(tq);
149		TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0);
150	}
151}
152
153void
154taskqueue_free(struct taskqueue *queue)
155{
156
157	TQ_LOCK(queue);
158	queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
159	taskqueue_terminate(queue->tq_threads, queue);
160	KASSERT(TAILQ_EMPTY(&queue->tq_active), ("Tasks still running?"));
161	KASSERT(queue->tq_callouts == 0, ("Armed timeout tasks"));
162	mtx_destroy(&queue->tq_mutex);
163	free(queue->tq_threads, M_TASKQUEUE);
164	free(queue, M_TASKQUEUE);
165}
166
167static int
168taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
169{
170	struct task *ins;
171	struct task *prev;
172
173	/*
174	 * Count multiple enqueues.
175	 */
176	if (task->ta_pending) {
177		if (task->ta_pending < USHRT_MAX)
178			task->ta_pending++;
179		return (0);
180	}
181
182	/*
183	 * Optimise the case when all tasks have the same priority.
184	 */
185	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
186	if (!prev || prev->ta_priority >= task->ta_priority) {
187		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
188	} else {
189		prev = NULL;
190		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
191		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
192			if (ins->ta_priority < task->ta_priority)
193				break;
194
195		if (prev)
196			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
197		else
198			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
199	}
200
201	task->ta_pending = 1;
202	if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0)
203		queue->tq_enqueue(queue->tq_context);
204	else
205		queue->tq_flags |= TQ_FLAGS_PENDING;
206
207	return (0);
208}
209int
210taskqueue_enqueue(struct taskqueue *queue, struct task *task)
211{
212	int res;
213
214	TQ_LOCK(queue);
215	res = taskqueue_enqueue_locked(queue, task);
216	TQ_UNLOCK(queue);
217
218	return (res);
219}
220
221static void
222taskqueue_timeout_func(void *arg)
223{
224	struct taskqueue *queue;
225	struct timeout_task *timeout_task;
226
227	timeout_task = arg;
228	queue = timeout_task->q;
229	KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
230	timeout_task->f &= ~DT_CALLOUT_ARMED;
231	queue->tq_callouts--;
232	taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
233}
234
235int
236taskqueue_enqueue_timeout(struct taskqueue *queue,
237    struct timeout_task *timeout_task, int ticks)
238{
239	int res;
240
241	TQ_LOCK(queue);
242	KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
243	    ("Migrated queue"));
244	KASSERT(!queue->tq_spin, ("Timeout for spin-queue"));
245	timeout_task->q = queue;
246	res = timeout_task->t.ta_pending;
247	if (ticks == 0) {
248		taskqueue_enqueue_locked(queue, &timeout_task->t);
249	} else {
250		if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
251			res++;
252		} else {
253			queue->tq_callouts++;
254			timeout_task->f |= DT_CALLOUT_ARMED;
255			if (ticks < 0)
256				ticks = -ticks; /* Ignore overflow. */
257		}
258		if (ticks > 0) {
259			callout_reset(&timeout_task->c, ticks,
260			    taskqueue_timeout_func, timeout_task);
261		}
262	}
263	TQ_UNLOCK(queue);
264	return (res);
265}
266
267void
268taskqueue_block(struct taskqueue *queue)
269{
270
271	TQ_LOCK(queue);
272	queue->tq_flags |= TQ_FLAGS_BLOCKED;
273	TQ_UNLOCK(queue);
274}
275
276void
277taskqueue_unblock(struct taskqueue *queue)
278{
279
280	TQ_LOCK(queue);
281	queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
282	if (queue->tq_flags & TQ_FLAGS_PENDING) {
283		queue->tq_flags &= ~TQ_FLAGS_PENDING;
284		queue->tq_enqueue(queue->tq_context);
285	}
286	TQ_UNLOCK(queue);
287}
288
289static void
290taskqueue_run_locked(struct taskqueue *queue)
291{
292	struct taskqueue_busy tb;
293	struct task *task;
294	int pending;
295
296	mtx_assert(&queue->tq_mutex, MA_OWNED);
297	tb.tb_running = NULL;
298	TAILQ_INSERT_TAIL(&queue->tq_active, &tb, tb_link);
299
300	while (STAILQ_FIRST(&queue->tq_queue)) {
301		/*
302		 * Carefully remove the first task from the queue and
303		 * zero its pending count.
304		 */
305		task = STAILQ_FIRST(&queue->tq_queue);
306		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
307		pending = task->ta_pending;
308		task->ta_pending = 0;
309		tb.tb_running = task;
310		TQ_UNLOCK(queue);
311
312		task->ta_func(task->ta_context, pending);
313
314		TQ_LOCK(queue);
315		tb.tb_running = NULL;
316		wakeup(task);
317	}
318	TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
319}
320
321void
322taskqueue_run(struct taskqueue *queue)
323{
324
325	TQ_LOCK(queue);
326	taskqueue_run_locked(queue);
327	TQ_UNLOCK(queue);
328}
329
330static int
331task_is_running(struct taskqueue *queue, struct task *task)
332{
333	struct taskqueue_busy *tb;
334
335	mtx_assert(&queue->tq_mutex, MA_OWNED);
336	TAILQ_FOREACH(tb, &queue->tq_active, tb_link) {
337		if (tb->tb_running == task)
338			return (1);
339	}
340	return (0);
341}
342
343static int
344taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
345    u_int *pendp)
346{
347
348	if (task->ta_pending > 0)
349		STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
350	if (pendp != NULL)
351		*pendp = task->ta_pending;
352	task->ta_pending = 0;
353	return (task_is_running(queue, task) ? EBUSY : 0);
354}
355
356int
357taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
358{
359	u_int pending;
360	int error;
361
362	TQ_LOCK(queue);
363	pending = task->ta_pending;
364	error = taskqueue_cancel_locked(queue, task, pendp);
365	TQ_UNLOCK(queue);
366
367	return (error);
368}
369
370int
371taskqueue_cancel_timeout(struct taskqueue *queue,
372    struct timeout_task *timeout_task, u_int *pendp)
373{
374	u_int pending, pending1;
375	int error;
376
377	TQ_LOCK(queue);
378	pending = !!callout_stop(&timeout_task->c);
379	error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
380	if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
381		timeout_task->f &= ~DT_CALLOUT_ARMED;
382		queue->tq_callouts--;
383	}
384	TQ_UNLOCK(queue);
385
386	if (pendp != NULL)
387		*pendp = pending + pending1;
388	return (error);
389}
390
391void
392taskqueue_drain(struct taskqueue *queue, struct task *task)
393{
394
395	if (!queue->tq_spin)
396		WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
397
398	TQ_LOCK(queue);
399	while (task->ta_pending != 0 || task_is_running(queue, task))
400		TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
401	TQ_UNLOCK(queue);
402}
403
404void
405taskqueue_drain_timeout(struct taskqueue *queue,
406    struct timeout_task *timeout_task)
407{
408
409	callout_drain(&timeout_task->c);
410	taskqueue_drain(queue, &timeout_task->t);
411}
412
413static void
414taskqueue_swi_enqueue(void *context)
415{
416	swi_sched(taskqueue_ih, 0);
417}
418
419static void
420taskqueue_swi_run(void *dummy)
421{
422	taskqueue_run(taskqueue_swi);
423}
424
425static void
426taskqueue_swi_giant_enqueue(void *context)
427{
428	swi_sched(taskqueue_giant_ih, 0);
429}
430
431static void
432taskqueue_swi_giant_run(void *dummy)
433{
434	taskqueue_run(taskqueue_swi_giant);
435}
436
437int
438taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
439			const char *name, ...)
440{
441	va_list ap;
442	struct thread *td;
443	struct taskqueue *tq;
444	int i, error;
445	char ktname[MAXCOMLEN + 1];
446
447	if (count <= 0)
448		return (EINVAL);
449
450	tq = *tqp;
451
452	va_start(ap, name);
453	vsnprintf(ktname, sizeof(ktname), name, ap);
454	va_end(ap);
455
456	tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
457	    M_NOWAIT | M_ZERO);
458	if (tq->tq_threads == NULL) {
459		printf("%s: no memory for %s threads\n", __func__, ktname);
460		return (ENOMEM);
461	}
462
463	for (i = 0; i < count; i++) {
464		if (count == 1)
465			error = kthread_add(taskqueue_thread_loop, tqp, NULL,
466			    &tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname);
467		else
468			error = kthread_add(taskqueue_thread_loop, tqp, NULL,
469			    &tq->tq_threads[i], RFSTOPPED, 0,
470			    "%s_%d", ktname, i);
471		if (error) {
472			/* should be ok to continue, taskqueue_free will dtrt */
473			printf("%s: kthread_add(%s): error %d", __func__,
474			    ktname, error);
475			tq->tq_threads[i] = NULL;		/* paranoid */
476		} else
477			tq->tq_tcount++;
478	}
479	for (i = 0; i < count; i++) {
480		if (tq->tq_threads[i] == NULL)
481			continue;
482		td = tq->tq_threads[i];
483		thread_lock(td);
484		sched_prio(td, pri);
485		sched_add(td, SRQ_BORING);
486		thread_unlock(td);
487	}
488
489	return (0);
490}
491
492void
493taskqueue_thread_loop(void *arg)
494{
495	struct taskqueue **tqp, *tq;
496
497	tqp = arg;
498	tq = *tqp;
499	TQ_LOCK(tq);
500	while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
501		taskqueue_run_locked(tq);
502		/*
503		 * Because taskqueue_run() can drop tq_mutex, we need to
504		 * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
505		 * meantime, which means we missed a wakeup.
506		 */
507		if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
508			break;
509		TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
510	}
511	taskqueue_run_locked(tq);
512
513	/* rendezvous with thread that asked us to terminate */
514	tq->tq_tcount--;
515	wakeup_one(tq->tq_threads);
516	TQ_UNLOCK(tq);
517	kthread_exit();
518}
519
520void
521taskqueue_thread_enqueue(void *context)
522{
523	struct taskqueue **tqp, *tq;
524
525	tqp = context;
526	tq = *tqp;
527
528	mtx_assert(&tq->tq_mutex, MA_OWNED);
529	wakeup_one(tq);
530}
531
532TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
533		 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
534		     INTR_MPSAFE, &taskqueue_ih));
535
536TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
537		 swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
538		     NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
539
540TASKQUEUE_DEFINE_THREAD(thread);
541
542struct taskqueue *
543taskqueue_create_fast(const char *name, int mflags,
544		 taskqueue_enqueue_fn enqueue, void *context)
545{
546	return _taskqueue_create(name, mflags, enqueue, context,
547			MTX_SPIN, "fast_taskqueue");
548}
549
550/* NB: for backwards compatibility */
551int
552taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
553{
554	return taskqueue_enqueue(queue, task);
555}
556
557static void	*taskqueue_fast_ih;
558
559static void
560taskqueue_fast_enqueue(void *context)
561{
562	swi_sched(taskqueue_fast_ih, 0);
563}
564
565static void
566taskqueue_fast_run(void *dummy)
567{
568	taskqueue_run(taskqueue_fast);
569}
570
571TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
572	swi_add(NULL, "fast taskq", taskqueue_fast_run, NULL,
573	SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
574
575int
576taskqueue_member(struct taskqueue *queue, struct thread *td)
577{
578	int i, j, ret = 0;
579
580	TQ_LOCK(queue);
581	for (i = 0, j = 0; ; i++) {
582		if (queue->tq_threads[i] == NULL)
583			continue;
584		if (queue->tq_threads[i] == td) {
585			ret = 1;
586			break;
587		}
588		if (++j >= queue->tq_tcount)
589			break;
590	}
591	TQ_UNLOCK(queue);
592	return (ret);
593}
594