xref: /dragonfly/sys/kern/subr_taskqueue.c (revision b608d1d3) 
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  * $FreeBSD: src/sys/kern/subr_taskqueue.c,v 1.69 2012/08/28 13:35:37 jhb Exp $"
27  */
28 
29 #include <sys/param.h>
30 #include <sys/queue.h>
31 #include <sys/systm.h>
32 #include <sys/kernel.h>
33 #include <sys/taskqueue.h>
34 #include <sys/interrupt.h>
35 #include <sys/lock.h>
36 #include <sys/malloc.h>
37 #include <sys/kthread.h>
38 #include <sys/spinlock.h>
39 #include <sys/spinlock2.h>
40 #include <sys/serialize.h>
41 #include <sys/proc.h>
42 
43 MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
44 
45 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
46 static struct lock	taskqueue_queues_lock;
47 
48 struct taskqueue {
49 	STAILQ_ENTRY(taskqueue)	tq_link;
50 	STAILQ_HEAD(, task)	tq_queue;
51 	const char		*tq_name;
52 	/* NOTE: tq must be locked before calling tq_enqueue */
53 	taskqueue_enqueue_fn	tq_enqueue;
54 	void			*tq_context;
55 
56 	struct task		*tq_running;
57 	struct spinlock		tq_lock;
58 	struct thread		**tq_threads;
59 	int			tq_tcount;
60 	int			tq_flags;
61 	int			tq_callouts;
62 };
63 
64 #define	TQ_FLAGS_ACTIVE		(1 << 0)
65 #define	TQ_FLAGS_BLOCKED	(1 << 1)
66 #define	TQ_FLAGS_PENDING	(1 << 2)
67 
68 #define	DT_CALLOUT_ARMED	(1 << 0)
69 
70 void
71 _timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
72     int priority, task_fn_t func, void *context)
73 {
74 
75 	TASK_INIT(&timeout_task->t, priority, func, context);
76 	callout_init(&timeout_task->c); /* XXX use callout_init_mp() */
77 	timeout_task->q = queue;
78 	timeout_task->f = 0;
79 }
80 
81 static void taskqueue_run(struct taskqueue *queue, int lock_held);
82 
83 static __inline void
84 TQ_LOCK_INIT(struct taskqueue *tq)
85 {
86 	spin_init(&tq->tq_lock, "tqlock");
87 }
88 
89 static __inline void
90 TQ_LOCK_UNINIT(struct taskqueue *tq)
91 {
92 	spin_uninit(&tq->tq_lock);
93 }
94 
95 static __inline void
96 TQ_LOCK(struct taskqueue *tq)
97 {
98 	spin_lock(&tq->tq_lock);
99 }
100 
101 static __inline void
102 TQ_UNLOCK(struct taskqueue *tq)
103 {
104 	spin_unlock(&tq->tq_lock);
105 }
106 
107 static __inline void
108 TQ_SLEEP(struct taskqueue *tq, void *ident, const char *wmesg)
109 {
110 	ssleep(ident, &tq->tq_lock, 0, wmesg, 0);
111 }
112 
113 struct taskqueue *
114 taskqueue_create(const char *name, int mflags,
115 		 taskqueue_enqueue_fn enqueue, void *context)
116 {
117 	struct taskqueue *queue;
118 
119 	queue = kmalloc(sizeof(*queue), M_TASKQUEUE, mflags | M_ZERO);
120 	if (!queue)
121 		return NULL;
122 	STAILQ_INIT(&queue->tq_queue);
123 	queue->tq_name = name;
124 	queue->tq_enqueue = enqueue;
125 	queue->tq_context = context;
126 	queue->tq_flags |= TQ_FLAGS_ACTIVE;
127 	TQ_LOCK_INIT(queue);
128 
129 	lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
130 	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
131 	lockmgr(&taskqueue_queues_lock, LK_RELEASE);
132 
133 	return queue;
134 }
135 
136 /* NOTE: tq must be locked */
137 static void
138 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
139 {
140 	while(tq->tq_tcount > 0) {
141 		/* Unlock spinlock before wakeup() */
142 		TQ_UNLOCK(tq);
143 		wakeup(tq);
144 		TQ_LOCK(tq);
145 		TQ_SLEEP(tq, pp, "taskqueue_terminate");
146 	}
147 }
148 
149 void
150 taskqueue_free(struct taskqueue *queue)
151 {
152 	TQ_LOCK(queue);
153 	queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
154 	taskqueue_run(queue, 1);
155 	taskqueue_terminate(queue->tq_threads, queue);
156 	TQ_UNLOCK(queue);
157 
158 	lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
159 	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
160 	lockmgr(&taskqueue_queues_lock, LK_RELEASE);
161 
162 	TQ_LOCK_UNINIT(queue);
163 
164 	kfree(queue, M_TASKQUEUE);
165 }
166 
167 struct taskqueue *
168 taskqueue_find(const char *name)
169 {
170 	struct taskqueue *queue;
171 
172 	lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
173 	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
174 		if (!strcmp(queue->tq_name, name)) {
175 			lockmgr(&taskqueue_queues_lock, LK_RELEASE);
176 			return queue;
177 		}
178 	}
179 	lockmgr(&taskqueue_queues_lock, LK_RELEASE);
180 	return NULL;
181 }
182 
183 /*
184  * NOTE!  If using the per-cpu taskqueues ``taskqueue_thread[mycpuid]'',
185  * be sure NOT TO SHARE the ``task'' between CPUs.  TASKS ARE NOT LOCKED.
186  * So either use a throwaway task which will only be enqueued once, or
187  * use one task per CPU!
188  */
189 static int
190 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
191 {
192 	struct task *ins;
193 	struct task *prev;
194 
195 	/*
196 	 * Don't allow new tasks on a queue which is being freed.
197 	 */
198 	if ((queue->tq_flags & TQ_FLAGS_ACTIVE) == 0)
199 		return EPIPE;
200 
201 	/*
202 	 * Count multiple enqueues.
203 	 */
204 	if (task->ta_pending) {
205 		task->ta_pending++;
206 		return 0;
207 	}
208 
209 	/*
210 	 * Optimise the case when all tasks have the same priority.
211 	 */
212 	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
213 	if (!prev || prev->ta_priority >= task->ta_priority) {
214 		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
215 	} else {
216 		prev = NULL;
217 		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
218 		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
219 			if (ins->ta_priority < task->ta_priority)
220 				break;
221 
222 		if (prev)
223 			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
224 		else
225 			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
226 	}
227 
228 	task->ta_pending = 1;
229 	if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0) {
230 		if (queue->tq_enqueue)
231 			queue->tq_enqueue(queue->tq_context);
232 	} else {
233 		queue->tq_flags |= TQ_FLAGS_PENDING;
234 	}
235 
236 	return 0;
237 }
238 
239 int
240 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
241 {
242 	int res;
243 
244 	TQ_LOCK(queue);
245 	res = taskqueue_enqueue_locked(queue, task);
246 	TQ_UNLOCK(queue);
247 
248 	return (res);
249 }
250 
251 static void
252 taskqueue_timeout_func(void *arg)
253 {
254 	struct taskqueue *queue;
255 	struct timeout_task *timeout_task;
256 
257 	timeout_task = arg;
258 	queue = timeout_task->q;
259 
260 	TQ_LOCK(queue);
261 	KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
262 	timeout_task->f &= ~DT_CALLOUT_ARMED;
263 	queue->tq_callouts--;
264 	taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
265 	TQ_UNLOCK(queue);
266 }
267 
268 int
269 taskqueue_enqueue_timeout(struct taskqueue *queue,
270     struct timeout_task *timeout_task, int ticks)
271 {
272 	int res;
273 
274 	TQ_LOCK(queue);
275 	KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
276 		("Migrated queue"));
277 	timeout_task->q = queue;
278 	res = timeout_task->t.ta_pending;
279 	if (ticks == 0) {
280 		taskqueue_enqueue_locked(queue, &timeout_task->t);
281 		TQ_UNLOCK(queue);
282 	} else {
283 		if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
284 			res++;
285 		} else {
286 			queue->tq_callouts++;
287 			timeout_task->f |= DT_CALLOUT_ARMED;
288 		}
289 		TQ_UNLOCK(queue);
290 		callout_reset(&timeout_task->c, ticks, taskqueue_timeout_func,
291 			      timeout_task);
292 	}
293 	return (res);
294 }
295 
296 void
297 taskqueue_block(struct taskqueue *queue)
298 {
299 	TQ_LOCK(queue);
300 	queue->tq_flags |= TQ_FLAGS_BLOCKED;
301 	TQ_UNLOCK(queue);
302 }
303 
304 void
305 taskqueue_unblock(struct taskqueue *queue)
306 {
307 	TQ_LOCK(queue);
308 	queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
309 	if (queue->tq_flags & TQ_FLAGS_PENDING) {
310 		queue->tq_flags &= ~TQ_FLAGS_PENDING;
311 		if (queue->tq_enqueue)
312 			queue->tq_enqueue(queue->tq_context);
313 	}
314 	TQ_UNLOCK(queue);
315 }
316 
317 static void
318 taskqueue_run(struct taskqueue *queue, int lock_held)
319 {
320 	struct task *task;
321 	int pending;
322 
323 	if (lock_held == 0)
324 		TQ_LOCK(queue);
325 	while (STAILQ_FIRST(&queue->tq_queue)) {
326 		/*
327 		 * Carefully remove the first task from the queue and
328 		 * zero its pending count.
329 		 */
330 		task = STAILQ_FIRST(&queue->tq_queue);
331 		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
332 		pending = task->ta_pending;
333 		task->ta_pending = 0;
334 		queue->tq_running = task;
335 
336 		TQ_UNLOCK(queue);
337 		task->ta_func(task->ta_context, pending);
338 		queue->tq_running = NULL;
339 		wakeup(task);
340 		TQ_LOCK(queue);
341 	}
342 	if (lock_held == 0)
343 		TQ_UNLOCK(queue);
344 }
345 
346 static int
347 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
348     u_int *pendp)
349 {
350 
351 	if (task->ta_pending > 0)
352 		STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
353 	if (pendp != NULL)
354 		*pendp = task->ta_pending;
355 	task->ta_pending = 0;
356 	return (task == queue->tq_running ? EBUSY : 0);
357 }
358 
359 int
360 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
361 {
362 	int error;
363 
364 	TQ_LOCK(queue);
365 	error = taskqueue_cancel_locked(queue, task, pendp);
366 	TQ_UNLOCK(queue);
367 
368 	return (error);
369 }
370 
371 int
372 taskqueue_cancel_timeout(struct taskqueue *queue,
373 			 struct timeout_task *timeout_task, u_int *pendp)
374 {
375 	u_int pending, pending1;
376 	int error;
377 
378 	pending = !!callout_stop(&timeout_task->c);
379 	TQ_LOCK(queue);
380 	error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
381 	if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
382 		timeout_task->f &= ~DT_CALLOUT_ARMED;
383 		queue->tq_callouts--;
384 	}
385 	TQ_UNLOCK(queue);
386 
387 	if (pendp != NULL)
388 		*pendp = pending + pending1;
389 	return (error);
390 }
391 
392 void
393 taskqueue_drain(struct taskqueue *queue, struct task *task)
394 {
395 	TQ_LOCK(queue);
396 	while (task->ta_pending != 0 || task == queue->tq_running)
397 		TQ_SLEEP(queue, task, "-");
398 	TQ_UNLOCK(queue);
399 }
400 
401 void
402 taskqueue_drain_timeout(struct taskqueue *queue,
403     struct timeout_task *timeout_task)
404 {
405 	callout_cancel(&timeout_task->c);
406 	taskqueue_drain(queue, &timeout_task->t);
407 }
408 
409 static void
410 taskqueue_swi_enqueue(void *context)
411 {
412 	setsofttq();
413 }
414 
415 static void
416 taskqueue_swi_run(void *arg, void *frame)
417 {
418 	taskqueue_run(taskqueue_swi, 0);
419 }
420 
421 static void
422 taskqueue_swi_mp_run(void *arg, void *frame)
423 {
424 	taskqueue_run(taskqueue_swi_mp, 0);
425 }
426 
427 int
428 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri, int ncpu,
429 			const char *fmt, ...)
430 {
431 	__va_list ap;
432 	struct thread *td;
433 	struct taskqueue *tq;
434 	int i, error, cpu;
435 	char ktname[MAXCOMLEN];
436 
437 	if (count <= 0)
438 		return EINVAL;
439 	/* catch call argument mistakes */
440 	KKASSERT(pri > 0 && pri < TDPRI_MAX);
441 
442 	tq = *tqp;
443 	cpu = ncpu;
444 
445 	__va_start(ap, fmt);
446 	kvsnprintf(ktname, MAXCOMLEN, fmt, ap);
447 	__va_end(ap);
448 
449 	tq->tq_threads = kmalloc(sizeof(struct thread *) * count, M_TASKQUEUE,
450 	    M_WAITOK | M_ZERO);
451 
452 	for (i = 0; i < count; i++) {
453 		/*
454 		 * If no specific cpu was specified and more than one thread
455 		 * is to be created, we distribute the threads amongst all
456 		 * cpus.
457 		 */
458 		if ((ncpu <= -1) && (count > 1))
459 			cpu = i%ncpus;
460 
461 		if (count == 1) {
462 			error = lwkt_create(taskqueue_thread_loop, tqp,
463 					    &tq->tq_threads[i], NULL,
464 					    TDF_NOSTART, cpu,
465 					    "%s", ktname);
466 		} else {
467 			error = lwkt_create(taskqueue_thread_loop, tqp,
468 					    &tq->tq_threads[i], NULL,
469 					    TDF_NOSTART, cpu,
470 					    "%s_%d", ktname, i);
471 		}
472 		if (error) {
473 			kprintf("%s: lwkt_create(%s): error %d", __func__,
474 			    ktname, error);
475 			tq->tq_threads[i] = NULL;
476 		} else {
477 			td = tq->tq_threads[i];
478 			lwkt_setpri_initial(td, pri);
479 			lwkt_schedule(td);
480 			tq->tq_tcount++;
481 		}
482 	}
483 
484 	return 0;
485 }
486 
487 void
488 taskqueue_thread_loop(void *arg)
489 {
490 	struct taskqueue **tqp, *tq;
491 
492 	tqp = arg;
493 	tq = *tqp;
494 	TQ_LOCK(tq);
495 	while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
496 		taskqueue_run(tq, 1);
497 		TQ_SLEEP(tq, tq, "tqthr");
498 	}
499 
500 	/* rendezvous with thread that asked us to terminate */
501 	tq->tq_tcount--;
502 	TQ_UNLOCK(tq);
503 	wakeup_one(tq->tq_threads);
504 	lwkt_exit();
505 }
506 
507 /* NOTE: tq must be locked */
508 void
509 taskqueue_thread_enqueue(void *context)
510 {
511 	struct taskqueue **tqp, *tq;
512 
513 	tqp = context;
514 	tq = *tqp;
515 
516 	/* Unlock spinlock before wakeup_one() */
517 	TQ_UNLOCK(tq);
518 	wakeup_one(tq);
519 	TQ_LOCK(tq);
520 }
521 
522 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
523 	 register_swi(SWI_TQ, taskqueue_swi_run, NULL, "swi_taskq", NULL, -1));
524 /*
525  * XXX: possibly use a different SWI_TQ_MP or so.
526  * related: sys/interrupt.h
527  * related: platform/XXX/isa/ipl_funcs.c
528  */
529 TASKQUEUE_DEFINE(swi_mp, taskqueue_swi_enqueue, 0,
530     register_swi_mp(SWI_TQ, taskqueue_swi_mp_run, NULL, "swi_mp_taskq", NULL,
531 		    -1));
532 
533 struct taskqueue *taskqueue_thread[MAXCPU];
534 
535 static void
536 taskqueue_init(void)
537 {
538 	int cpu;
539 
540 	lockinit(&taskqueue_queues_lock, "tqqueues", 0, 0);
541 	STAILQ_INIT(&taskqueue_queues);
542 
543 	for (cpu = 0; cpu < ncpus; cpu++) {
544 		taskqueue_thread[cpu] = taskqueue_create("thread", M_INTWAIT,
545 		    taskqueue_thread_enqueue, &taskqueue_thread[cpu]);
546 		taskqueue_start_threads(&taskqueue_thread[cpu], 1,
547 		    TDPRI_KERN_DAEMON, cpu, "taskq_cpu %d", cpu);
548 	}
549 }
550 
551 SYSINIT(taskqueueinit, SI_SUB_PRE_DRIVERS, SI_ORDER_ANY, taskqueue_init, NULL);
552