xref: /freebsd/sys/kern/subr_taskqueue.c (revision 38d120bc13ac1de5b739b67b87016b9122149374)
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/cpuset.h>
34 #include <sys/interrupt.h>
35 #include <sys/kernel.h>
36 #include <sys/kthread.h>
37 #include <sys/limits.h>
38 #include <sys/lock.h>
39 #include <sys/malloc.h>
40 #include <sys/mutex.h>
41 #include <sys/proc.h>
42 #include <sys/sched.h>
43 #include <sys/taskqueue.h>
44 #include <sys/unistd.h>
45 #include <machine/stdarg.h>
46 
47 static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
48 static void	*taskqueue_giant_ih;
49 static void	*taskqueue_ih;
50 static void	 taskqueue_fast_enqueue(void *);
51 static void	 taskqueue_swi_enqueue(void *);
52 static void	 taskqueue_swi_giant_enqueue(void *);
53 
54 struct taskqueue_busy {
55 	struct task	*tb_running;
56 	TAILQ_ENTRY(taskqueue_busy) tb_link;
57 };
58 
59 struct taskqueue {
60 	STAILQ_HEAD(, task)	tq_queue;
61 	taskqueue_enqueue_fn	tq_enqueue;
62 	void			*tq_context;
63 	TAILQ_HEAD(, taskqueue_busy) tq_active;
64 	struct mtx		tq_mutex;
65 	struct thread		**tq_threads;
66 	int			tq_tcount;
67 	int			tq_spin;
68 	int			tq_flags;
69 	int			tq_callouts;
70 	taskqueue_callback_fn	tq_callbacks[TASKQUEUE_NUM_CALLBACKS];
71 	void			*tq_cb_contexts[TASKQUEUE_NUM_CALLBACKS];
72 };
73 
74 #define	TQ_FLAGS_ACTIVE		(1 << 0)
75 #define	TQ_FLAGS_BLOCKED	(1 << 1)
76 #define	TQ_FLAGS_UNLOCKED_ENQUEUE	(1 << 2)
77 
78 #define	DT_CALLOUT_ARMED	(1 << 0)
79 
80 #define	TQ_LOCK(tq)							\
81 	do {								\
82 		if ((tq)->tq_spin)					\
83 			mtx_lock_spin(&(tq)->tq_mutex);			\
84 		else							\
85 			mtx_lock(&(tq)->tq_mutex);			\
86 	} while (0)
87 #define	TQ_ASSERT_LOCKED(tq)	mtx_assert(&(tq)->tq_mutex, MA_OWNED)
88 
89 #define	TQ_UNLOCK(tq)							\
90 	do {								\
91 		if ((tq)->tq_spin)					\
92 			mtx_unlock_spin(&(tq)->tq_mutex);		\
93 		else							\
94 			mtx_unlock(&(tq)->tq_mutex);			\
95 	} while (0)
96 #define	TQ_ASSERT_UNLOCKED(tq)	mtx_assert(&(tq)->tq_mutex, MA_NOTOWNED)
97 
98 void
99 _timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
100     int priority, task_fn_t func, void *context)
101 {
102 
103 	TASK_INIT(&timeout_task->t, priority, func, context);
104 	callout_init_mtx(&timeout_task->c, &queue->tq_mutex,
105 	    CALLOUT_RETURNUNLOCKED);
106 	timeout_task->q = queue;
107 	timeout_task->f = 0;
108 }
109 
110 static __inline int
111 TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm,
112     int t)
113 {
114 	if (tq->tq_spin)
115 		return (msleep_spin(p, m, wm, t));
116 	return (msleep(p, m, pri, wm, t));
117 }
118 
119 static struct taskqueue *
120 _taskqueue_create(const char *name __unused, int mflags,
121 		 taskqueue_enqueue_fn enqueue, void *context,
122 		 int mtxflags, const char *mtxname)
123 {
124 	struct taskqueue *queue;
125 
126 	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
127 	if (!queue)
128 		return NULL;
129 
130 	STAILQ_INIT(&queue->tq_queue);
131 	TAILQ_INIT(&queue->tq_active);
132 	queue->tq_enqueue = enqueue;
133 	queue->tq_context = context;
134 	queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
135 	queue->tq_flags |= TQ_FLAGS_ACTIVE;
136 	if (enqueue == taskqueue_fast_enqueue ||
137 	    enqueue == taskqueue_swi_enqueue ||
138 	    enqueue == taskqueue_swi_giant_enqueue ||
139 	    enqueue == taskqueue_thread_enqueue)
140 		queue->tq_flags |= TQ_FLAGS_UNLOCKED_ENQUEUE;
141 	mtx_init(&queue->tq_mutex, mtxname, NULL, mtxflags);
142 
143 	return queue;
144 }
145 
146 struct taskqueue *
147 taskqueue_create(const char *name, int mflags,
148 		 taskqueue_enqueue_fn enqueue, void *context)
149 {
150 	return _taskqueue_create(name, mflags, enqueue, context,
151 			MTX_DEF, "taskqueue");
152 }
153 
154 void
155 taskqueue_set_callback(struct taskqueue *queue,
156     enum taskqueue_callback_type cb_type, taskqueue_callback_fn callback,
157     void *context)
158 {
159 
160 	KASSERT(((cb_type >= TASKQUEUE_CALLBACK_TYPE_MIN) &&
161 	    (cb_type <= TASKQUEUE_CALLBACK_TYPE_MAX)),
162 	    ("Callback type %d not valid, must be %d-%d", cb_type,
163 	    TASKQUEUE_CALLBACK_TYPE_MIN, TASKQUEUE_CALLBACK_TYPE_MAX));
164 	KASSERT((queue->tq_callbacks[cb_type] == NULL),
165 	    ("Re-initialization of taskqueue callback?"));
166 
167 	queue->tq_callbacks[cb_type] = callback;
168 	queue->tq_cb_contexts[cb_type] = context;
169 }
170 
171 /*
172  * Signal a taskqueue thread to terminate.
173  */
174 static void
175 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
176 {
177 
178 	while (tq->tq_tcount > 0 || tq->tq_callouts > 0) {
179 		wakeup(tq);
180 		TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0);
181 	}
182 }
183 
184 void
185 taskqueue_free(struct taskqueue *queue)
186 {
187 
188 	TQ_LOCK(queue);
189 	queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
190 	taskqueue_terminate(queue->tq_threads, queue);
191 	KASSERT(TAILQ_EMPTY(&queue->tq_active), ("Tasks still running?"));
192 	KASSERT(queue->tq_callouts == 0, ("Armed timeout tasks"));
193 	mtx_destroy(&queue->tq_mutex);
194 	free(queue->tq_threads, M_TASKQUEUE);
195 	free(queue, M_TASKQUEUE);
196 }
197 
198 static int
199 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
200 {
201 	struct task *ins;
202 	struct task *prev;
203 
204 	/*
205 	 * Count multiple enqueues.
206 	 */
207 	if (task->ta_pending) {
208 		if (task->ta_pending < USHRT_MAX)
209 			task->ta_pending++;
210 		TQ_UNLOCK(queue);
211 		return (0);
212 	}
213 
214 	/*
215 	 * Optimise the case when all tasks have the same priority.
216 	 */
217 	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
218 	if (!prev || prev->ta_priority >= task->ta_priority) {
219 		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
220 	} else {
221 		prev = NULL;
222 		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
223 		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
224 			if (ins->ta_priority < task->ta_priority)
225 				break;
226 
227 		if (prev)
228 			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
229 		else
230 			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
231 	}
232 
233 	task->ta_pending = 1;
234 	if ((queue->tq_flags & TQ_FLAGS_UNLOCKED_ENQUEUE) != 0)
235 		TQ_UNLOCK(queue);
236 	if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0)
237 		queue->tq_enqueue(queue->tq_context);
238 	if ((queue->tq_flags & TQ_FLAGS_UNLOCKED_ENQUEUE) == 0)
239 		TQ_UNLOCK(queue);
240 
241 	/* Return with lock released. */
242 	return (0);
243 }
244 int
245 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
246 {
247 	int res;
248 
249 	TQ_LOCK(queue);
250 	res = taskqueue_enqueue_locked(queue, task);
251 	/* The lock is released inside. */
252 
253 	return (res);
254 }
255 
256 static void
257 taskqueue_timeout_func(void *arg)
258 {
259 	struct taskqueue *queue;
260 	struct timeout_task *timeout_task;
261 
262 	timeout_task = arg;
263 	queue = timeout_task->q;
264 	KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
265 	timeout_task->f &= ~DT_CALLOUT_ARMED;
266 	queue->tq_callouts--;
267 	taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
268 	/* The lock is released inside. */
269 }
270 
271 int
272 taskqueue_enqueue_timeout(struct taskqueue *queue,
273     struct timeout_task *timeout_task, int ticks)
274 {
275 	int res;
276 
277 	TQ_LOCK(queue);
278 	KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
279 	    ("Migrated queue"));
280 	KASSERT(!queue->tq_spin, ("Timeout for spin-queue"));
281 	timeout_task->q = queue;
282 	res = timeout_task->t.ta_pending;
283 	if (ticks == 0) {
284 		taskqueue_enqueue_locked(queue, &timeout_task->t);
285 		/* The lock is released inside. */
286 	} else {
287 		if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
288 			res++;
289 		} else {
290 			queue->tq_callouts++;
291 			timeout_task->f |= DT_CALLOUT_ARMED;
292 			if (ticks < 0)
293 				ticks = -ticks; /* Ignore overflow. */
294 		}
295 		if (ticks > 0) {
296 			callout_reset(&timeout_task->c, ticks,
297 			    taskqueue_timeout_func, timeout_task);
298 		}
299 		TQ_UNLOCK(queue);
300 	}
301 	return (res);
302 }
303 
304 static void
305 taskqueue_drain_running(struct taskqueue *queue)
306 {
307 
308 	while (!TAILQ_EMPTY(&queue->tq_active))
309 		TQ_SLEEP(queue, &queue->tq_active, &queue->tq_mutex,
310 		    PWAIT, "-", 0);
311 }
312 
313 void
314 taskqueue_block(struct taskqueue *queue)
315 {
316 
317 	TQ_LOCK(queue);
318 	queue->tq_flags |= TQ_FLAGS_BLOCKED;
319 	TQ_UNLOCK(queue);
320 }
321 
322 void
323 taskqueue_unblock(struct taskqueue *queue)
324 {
325 
326 	TQ_LOCK(queue);
327 	queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
328 	if (!STAILQ_EMPTY(&queue->tq_queue))
329 		queue->tq_enqueue(queue->tq_context);
330 	TQ_UNLOCK(queue);
331 }
332 
333 static void
334 taskqueue_run_locked(struct taskqueue *queue)
335 {
336 	struct taskqueue_busy tb;
337 	struct task *task;
338 	int pending;
339 
340 	TQ_ASSERT_LOCKED(queue);
341 	tb.tb_running = NULL;
342 	TAILQ_INSERT_TAIL(&queue->tq_active, &tb, tb_link);
343 
344 	while (STAILQ_FIRST(&queue->tq_queue)) {
345 		/*
346 		 * Carefully remove the first task from the queue and
347 		 * zero its pending count.
348 		 */
349 		task = STAILQ_FIRST(&queue->tq_queue);
350 		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
351 		pending = task->ta_pending;
352 		task->ta_pending = 0;
353 		tb.tb_running = task;
354 		TQ_UNLOCK(queue);
355 
356 		task->ta_func(task->ta_context, pending);
357 
358 		TQ_LOCK(queue);
359 		tb.tb_running = NULL;
360 		wakeup(task);
361 	}
362 	TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
363 	if (TAILQ_EMPTY(&queue->tq_active))
364 		wakeup(&queue->tq_active);
365 }
366 
367 void
368 taskqueue_run(struct taskqueue *queue)
369 {
370 
371 	TQ_LOCK(queue);
372 	taskqueue_run_locked(queue);
373 	TQ_UNLOCK(queue);
374 }
375 
376 static int
377 task_is_running(struct taskqueue *queue, struct task *task)
378 {
379 	struct taskqueue_busy *tb;
380 
381 	TQ_ASSERT_LOCKED(queue);
382 	TAILQ_FOREACH(tb, &queue->tq_active, tb_link) {
383 		if (tb->tb_running == task)
384 			return (1);
385 	}
386 	return (0);
387 }
388 
389 static int
390 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
391     u_int *pendp)
392 {
393 
394 	if (task->ta_pending > 0)
395 		STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
396 	if (pendp != NULL)
397 		*pendp = task->ta_pending;
398 	task->ta_pending = 0;
399 	return (task_is_running(queue, task) ? EBUSY : 0);
400 }
401 
402 int
403 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
404 {
405 	int error;
406 
407 	TQ_LOCK(queue);
408 	error = taskqueue_cancel_locked(queue, task, pendp);
409 	TQ_UNLOCK(queue);
410 
411 	return (error);
412 }
413 
414 int
415 taskqueue_cancel_timeout(struct taskqueue *queue,
416     struct timeout_task *timeout_task, u_int *pendp)
417 {
418 	u_int pending, pending1;
419 	int error;
420 
421 	TQ_LOCK(queue);
422 	pending = !!callout_stop(&timeout_task->c);
423 	error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
424 	if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
425 		timeout_task->f &= ~DT_CALLOUT_ARMED;
426 		queue->tq_callouts--;
427 	}
428 	TQ_UNLOCK(queue);
429 
430 	if (pendp != NULL)
431 		*pendp = pending + pending1;
432 	return (error);
433 }
434 
435 void
436 taskqueue_drain(struct taskqueue *queue, struct task *task)
437 {
438 
439 	if (!queue->tq_spin)
440 		WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
441 
442 	TQ_LOCK(queue);
443 	while (task->ta_pending != 0 || task_is_running(queue, task))
444 		TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
445 	TQ_UNLOCK(queue);
446 }
447 
448 void
449 taskqueue_drain_all(struct taskqueue *queue)
450 {
451 	struct task *task;
452 
453 	if (!queue->tq_spin)
454 		WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
455 
456 	TQ_LOCK(queue);
457 	task = STAILQ_LAST(&queue->tq_queue, task, ta_link);
458 	if (task != NULL)
459 		while (task->ta_pending != 0)
460 			TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
461 	taskqueue_drain_running(queue);
462 	KASSERT(STAILQ_EMPTY(&queue->tq_queue),
463 	    ("taskqueue queue is not empty after draining"));
464 	TQ_UNLOCK(queue);
465 }
466 
467 void
468 taskqueue_drain_timeout(struct taskqueue *queue,
469     struct timeout_task *timeout_task)
470 {
471 
472 	callout_drain(&timeout_task->c);
473 	taskqueue_drain(queue, &timeout_task->t);
474 }
475 
476 static void
477 taskqueue_swi_enqueue(void *context)
478 {
479 	swi_sched(taskqueue_ih, 0);
480 }
481 
482 static void
483 taskqueue_swi_run(void *dummy)
484 {
485 	taskqueue_run(taskqueue_swi);
486 }
487 
488 static void
489 taskqueue_swi_giant_enqueue(void *context)
490 {
491 	swi_sched(taskqueue_giant_ih, 0);
492 }
493 
494 static void
495 taskqueue_swi_giant_run(void *dummy)
496 {
497 	taskqueue_run(taskqueue_swi_giant);
498 }
499 
500 static int
501 _taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
502     cpuset_t *mask, const char *ktname)
503 {
504 	struct thread *td;
505 	struct taskqueue *tq;
506 	int i, error;
507 
508 	if (count <= 0)
509 		return (EINVAL);
510 
511 	tq = *tqp;
512 
513 	tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
514 	    M_NOWAIT | M_ZERO);
515 	if (tq->tq_threads == NULL) {
516 		printf("%s: no memory for %s threads\n", __func__, ktname);
517 		return (ENOMEM);
518 	}
519 
520 	for (i = 0; i < count; i++) {
521 		if (count == 1)
522 			error = kthread_add(taskqueue_thread_loop, tqp, NULL,
523 			    &tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname);
524 		else
525 			error = kthread_add(taskqueue_thread_loop, tqp, NULL,
526 			    &tq->tq_threads[i], RFSTOPPED, 0,
527 			    "%s_%d", ktname, i);
528 		if (error) {
529 			/* should be ok to continue, taskqueue_free will dtrt */
530 			printf("%s: kthread_add(%s): error %d", __func__,
531 			    ktname, error);
532 			tq->tq_threads[i] = NULL;		/* paranoid */
533 		} else
534 			tq->tq_tcount++;
535 	}
536 	for (i = 0; i < count; i++) {
537 		if (tq->tq_threads[i] == NULL)
538 			continue;
539 		td = tq->tq_threads[i];
540 		if (mask) {
541 			error = cpuset_setthread(td->td_tid, mask);
542 			/*
543 			 * Failing to pin is rarely an actual fatal error;
544 			 * it'll just affect performance.
545 			 */
546 			if (error)
547 				printf("%s: curthread=%llu: can't pin; "
548 				    "error=%d\n",
549 				    __func__,
550 				    (unsigned long long) td->td_tid,
551 				    error);
552 		}
553 		thread_lock(td);
554 		sched_prio(td, pri);
555 		sched_add(td, SRQ_BORING);
556 		thread_unlock(td);
557 	}
558 
559 	return (0);
560 }
561 
562 int
563 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
564     const char *name, ...)
565 {
566 	char ktname[MAXCOMLEN + 1];
567 	va_list ap;
568 
569 	va_start(ap, name);
570 	vsnprintf(ktname, sizeof(ktname), name, ap);
571 	va_end(ap);
572 
573 	return (_taskqueue_start_threads(tqp, count, pri, NULL, ktname));
574 }
575 
576 int
577 taskqueue_start_threads_pinned(struct taskqueue **tqp, int count, int pri,
578     int cpu_id, const char *name, ...)
579 {
580 	char ktname[MAXCOMLEN + 1];
581 	va_list ap;
582 	cpuset_t mask;
583 
584 	va_start(ap, name);
585 	vsnprintf(ktname, sizeof(ktname), name, ap);
586 	va_end(ap);
587 
588 	/*
589 	 * In case someone passes in NOCPU, just fall back to the
590 	 * default behaviour of "don't pin".
591 	 */
592 	if (cpu_id != NOCPU) {
593 		CPU_ZERO(&mask);
594 		CPU_SET(cpu_id, &mask);
595 	}
596 
597 	return (_taskqueue_start_threads(tqp, count, pri,
598 	    cpu_id == NOCPU ? NULL : &mask, ktname));
599 }
600 
601 static inline void
602 taskqueue_run_callback(struct taskqueue *tq,
603     enum taskqueue_callback_type cb_type)
604 {
605 	taskqueue_callback_fn tq_callback;
606 
607 	TQ_ASSERT_UNLOCKED(tq);
608 	tq_callback = tq->tq_callbacks[cb_type];
609 	if (tq_callback != NULL)
610 		tq_callback(tq->tq_cb_contexts[cb_type]);
611 }
612 
613 void
614 taskqueue_thread_loop(void *arg)
615 {
616 	struct taskqueue **tqp, *tq;
617 
618 	tqp = arg;
619 	tq = *tqp;
620 	taskqueue_run_callback(tq, TASKQUEUE_CALLBACK_TYPE_INIT);
621 	TQ_LOCK(tq);
622 	while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
623 		taskqueue_run_locked(tq);
624 		/*
625 		 * Because taskqueue_run() can drop tq_mutex, we need to
626 		 * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
627 		 * meantime, which means we missed a wakeup.
628 		 */
629 		if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
630 			break;
631 		TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
632 	}
633 	taskqueue_run_locked(tq);
634 
635 	/*
636 	 * This thread is on its way out, so just drop the lock temporarily
637 	 * in order to call the shutdown callback.  This allows the callback
638 	 * to look at the taskqueue, even just before it dies.
639 	 */
640 	TQ_UNLOCK(tq);
641 	taskqueue_run_callback(tq, TASKQUEUE_CALLBACK_TYPE_SHUTDOWN);
642 	TQ_LOCK(tq);
643 
644 	/* rendezvous with thread that asked us to terminate */
645 	tq->tq_tcount--;
646 	wakeup_one(tq->tq_threads);
647 	TQ_UNLOCK(tq);
648 	kthread_exit();
649 }
650 
651 void
652 taskqueue_thread_enqueue(void *context)
653 {
654 	struct taskqueue **tqp, *tq;
655 
656 	tqp = context;
657 	tq = *tqp;
658 
659 	wakeup_one(tq);
660 }
661 
662 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
663 		 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
664 		     INTR_MPSAFE, &taskqueue_ih));
665 
666 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
667 		 swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
668 		     NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
669 
670 TASKQUEUE_DEFINE_THREAD(thread);
671 
672 struct taskqueue *
673 taskqueue_create_fast(const char *name, int mflags,
674 		 taskqueue_enqueue_fn enqueue, void *context)
675 {
676 	return _taskqueue_create(name, mflags, enqueue, context,
677 			MTX_SPIN, "fast_taskqueue");
678 }
679 
680 /* NB: for backwards compatibility */
681 int
682 taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
683 {
684 	return taskqueue_enqueue(queue, task);
685 }
686 
687 static void	*taskqueue_fast_ih;
688 
689 static void
690 taskqueue_fast_enqueue(void *context)
691 {
692 	swi_sched(taskqueue_fast_ih, 0);
693 }
694 
695 static void
696 taskqueue_fast_run(void *dummy)
697 {
698 	taskqueue_run(taskqueue_fast);
699 }
700 
701 TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
702 	swi_add(NULL, "fast taskq", taskqueue_fast_run, NULL,
703 	SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
704 
705 int
706 taskqueue_member(struct taskqueue *queue, struct thread *td)
707 {
708 	int i, j, ret = 0;
709 
710 	for (i = 0, j = 0; ; i++) {
711 		if (queue->tq_threads[i] == NULL)
712 			continue;
713 		if (queue->tq_threads[i] == td) {
714 			ret = 1;
715 			break;
716 		}
717 		if (++j >= queue->tq_tcount)
718 			break;
719 	}
720 	return (ret);
721 }
722