xref: /dragonfly/sys/kern/subr_taskqueue.c (revision c17e6018) 
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/thread2.h>
39 #include <sys/spinlock.h>
40 #include <sys/spinlock2.h>
41 #include <sys/serialize.h>
42 #include <sys/proc.h>
43 #include <machine/varargs.h>
44 
45 MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
46 
47 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
48 static struct lock	taskqueue_queues_lock;
49 
50 struct taskqueue {
51 	STAILQ_ENTRY(taskqueue)	tq_link;
52 	STAILQ_HEAD(, task)	tq_queue;
53 	const char		*tq_name;
54 	/* NOTE: tq must be locked before calling tq_enqueue */
55 	taskqueue_enqueue_fn	tq_enqueue;
56 	void			*tq_context;
57 
58 	struct task		*tq_running;
59 	struct spinlock		tq_lock;
60 	struct thread		**tq_threads;
61 	int			tq_tcount;
62 	int			tq_flags;
63 	int			tq_callouts;
64 };
65 
66 #define	TQ_FLAGS_ACTIVE		(1 << 0)
67 #define	TQ_FLAGS_BLOCKED	(1 << 1)
68 #define	TQ_FLAGS_PENDING	(1 << 2)
69 
70 #define	DT_CALLOUT_ARMED	(1 << 0)
71 
72 void
73 _timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
74     int priority, task_fn_t func, void *context)
75 {
76 
77 	TASK_INIT(&timeout_task->t, priority, func, context);
78 	callout_init(&timeout_task->c); /* XXX use callout_init_mp() */
79 	timeout_task->q = queue;
80 	timeout_task->f = 0;
81 }
82 
83 static void taskqueue_run(struct taskqueue *queue, int lock_held);
84 
85 static __inline void
86 TQ_LOCK_INIT(struct taskqueue *tq)
87 {
88 	spin_init(&tq->tq_lock, "tqlock");
89 }
90 
91 static __inline void
92 TQ_LOCK_UNINIT(struct taskqueue *tq)
93 {
94 	spin_uninit(&tq->tq_lock);
95 }
96 
97 static __inline void
98 TQ_LOCK(struct taskqueue *tq)
99 {
100 	spin_lock(&tq->tq_lock);
101 }
102 
103 static __inline void
104 TQ_UNLOCK(struct taskqueue *tq)
105 {
106 	spin_unlock(&tq->tq_lock);
107 }
108 
109 static __inline void
110 TQ_SLEEP(struct taskqueue *tq, void *ident, const char *wmesg)
111 {
112 	ssleep(ident, &tq->tq_lock, 0, wmesg, 0);
113 }
114 
115 struct taskqueue *
116 taskqueue_create(const char *name, int mflags,
117 		 taskqueue_enqueue_fn enqueue, void *context)
118 {
119 	struct taskqueue *queue;
120 
121 	queue = kmalloc(sizeof(*queue), M_TASKQUEUE, mflags | M_ZERO);
122 	if (!queue)
123 		return NULL;
124 	STAILQ_INIT(&queue->tq_queue);
125 	queue->tq_name = name;
126 	queue->tq_enqueue = enqueue;
127 	queue->tq_context = context;
128 	queue->tq_flags |= TQ_FLAGS_ACTIVE;
129 	TQ_LOCK_INIT(queue);
130 
131 	lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
132 	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
133 	lockmgr(&taskqueue_queues_lock, LK_RELEASE);
134 
135 	return queue;
136 }
137 
138 /* NOTE: tq must be locked */
139 static void
140 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
141 {
142 	while(tq->tq_tcount > 0) {
143 		/* Unlock spinlock before wakeup() */
144 		TQ_UNLOCK(tq);
145 		wakeup(tq);
146 		TQ_LOCK(tq);
147 		TQ_SLEEP(tq, pp, "taskqueue_terminate");
148 	}
149 }
150 
151 void
152 taskqueue_free(struct taskqueue *queue)
153 {
154 	TQ_LOCK(queue);
155 	queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
156 	taskqueue_run(queue, 1);
157 	taskqueue_terminate(queue->tq_threads, queue);
158 	TQ_UNLOCK(queue);
159 
160 	lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
161 	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
162 	lockmgr(&taskqueue_queues_lock, LK_RELEASE);
163 
164 	TQ_LOCK_UNINIT(queue);
165 
166 	kfree(queue, M_TASKQUEUE);
167 }
168 
169 struct taskqueue *
170 taskqueue_find(const char *name)
171 {
172 	struct taskqueue *queue;
173 
174 	lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
175 	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
176 		if (!strcmp(queue->tq_name, name)) {
177 			lockmgr(&taskqueue_queues_lock, LK_RELEASE);
178 			return queue;
179 		}
180 	}
181 	lockmgr(&taskqueue_queues_lock, LK_RELEASE);
182 	return NULL;
183 }
184 
185 /*
186  * NOTE!  If using the per-cpu taskqueues ``taskqueue_thread[mycpuid]'',
187  * be sure NOT TO SHARE the ``task'' between CPUs.  TASKS ARE NOT LOCKED.
188  * So either use a throwaway task which will only be enqueued once, or
189  * use one task per CPU!
190  */
191 static int
192 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
193 {
194 	struct task *ins;
195 	struct task *prev;
196 
197 	/*
198 	 * Don't allow new tasks on a queue which is being freed.
199 	 */
200 	if ((queue->tq_flags & TQ_FLAGS_ACTIVE) == 0)
201 		return EPIPE;
202 
203 	/*
204 	 * Count multiple enqueues.
205 	 */
206 	if (task->ta_pending) {
207 		task->ta_pending++;
208 		return 0;
209 	}
210 
211 	/*
212 	 * Optimise the case when all tasks have the same priority.
213 	 */
214 	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
215 	if (!prev || prev->ta_priority >= task->ta_priority) {
216 		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
217 	} else {
218 		prev = NULL;
219 		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
220 		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
221 			if (ins->ta_priority < task->ta_priority)
222 				break;
223 
224 		if (prev)
225 			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
226 		else
227 			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
228 	}
229 
230 	task->ta_pending = 1;
231 	if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0) {
232 		if (queue->tq_enqueue)
233 			queue->tq_enqueue(queue->tq_context);
234 	} else {
235 		queue->tq_flags |= TQ_FLAGS_PENDING;
236 	}
237 
238 	return 0;
239 }
240 
241 int
242 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
243 {
244 	int res;
245 
246 	TQ_LOCK(queue);
247 	res = taskqueue_enqueue_locked(queue, task);
248 	TQ_UNLOCK(queue);
249 
250 	return (res);
251 }
252 
253 static void
254 taskqueue_timeout_func(void *arg)
255 {
256 	struct taskqueue *queue;
257 	struct timeout_task *timeout_task;
258 
259 	timeout_task = arg;
260 	queue = timeout_task->q;
261 
262 	TQ_LOCK(queue);
263 	KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
264 	timeout_task->f &= ~DT_CALLOUT_ARMED;
265 	queue->tq_callouts--;
266 	taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
267 	TQ_UNLOCK(queue);
268 }
269 
270 int
271 taskqueue_enqueue_timeout(struct taskqueue *queue,
272     struct timeout_task *timeout_task, int ticks)
273 {
274 	int res;
275 
276 	TQ_LOCK(queue);
277 	KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
278 		("Migrated queue"));
279 	timeout_task->q = queue;
280 	res = timeout_task->t.ta_pending;
281 	if (ticks == 0) {
282 		taskqueue_enqueue_locked(queue, &timeout_task->t);
283 		TQ_UNLOCK(queue);
284 	} else {
285 		if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
286 			res++;
287 		} else {
288 			queue->tq_callouts++;
289 			timeout_task->f |= DT_CALLOUT_ARMED;
290 		}
291 		TQ_UNLOCK(queue);
292 		callout_reset(&timeout_task->c, ticks, taskqueue_timeout_func,
293 			      timeout_task);
294 	}
295 	return (res);
296 }
297 
298 void
299 taskqueue_block(struct taskqueue *queue)
300 {
301 	TQ_LOCK(queue);
302 	queue->tq_flags |= TQ_FLAGS_BLOCKED;
303 	TQ_UNLOCK(queue);
304 }
305 
306 void
307 taskqueue_unblock(struct taskqueue *queue)
308 {
309 	TQ_LOCK(queue);
310 	queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
311 	if (queue->tq_flags & TQ_FLAGS_PENDING) {
312 		queue->tq_flags &= ~TQ_FLAGS_PENDING;
313 		if (queue->tq_enqueue)
314 			queue->tq_enqueue(queue->tq_context);
315 	}
316 	TQ_UNLOCK(queue);
317 }
318 
319 static void
320 taskqueue_run(struct taskqueue *queue, int lock_held)
321 {
322 	struct task *task;
323 	int pending;
324 
325 	if (lock_held == 0)
326 		TQ_LOCK(queue);
327 	while (STAILQ_FIRST(&queue->tq_queue)) {
328 		/*
329 		 * Carefully remove the first task from the queue and
330 		 * zero its pending count.
331 		 */
332 		task = STAILQ_FIRST(&queue->tq_queue);
333 		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
334 		pending = task->ta_pending;
335 		task->ta_pending = 0;
336 		queue->tq_running = task;
337 
338 		TQ_UNLOCK(queue);
339 		task->ta_func(task->ta_context, pending);
340 		queue->tq_running = NULL;
341 		wakeup(task);
342 		TQ_LOCK(queue);
343 	}
344 	if (lock_held == 0)
345 		TQ_UNLOCK(queue);
346 }
347 
348 static int
349 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
350     u_int *pendp)
351 {
352 
353 	if (task->ta_pending > 0)
354 		STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
355 	if (pendp != NULL)
356 		*pendp = task->ta_pending;
357 	task->ta_pending = 0;
358 	return (task == queue->tq_running ? EBUSY : 0);
359 }
360 
361 int
362 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
363 {
364 	int error;
365 
366 	TQ_LOCK(queue);
367 	error = taskqueue_cancel_locked(queue, task, pendp);
368 	TQ_UNLOCK(queue);
369 
370 	return (error);
371 }
372 
373 int
374 taskqueue_cancel_timeout(struct taskqueue *queue,
375 			 struct timeout_task *timeout_task, u_int *pendp)
376 {
377 	u_int pending, pending1;
378 	int error;
379 
380 	pending = !!callout_stop(&timeout_task->c);
381 	TQ_LOCK(queue);
382 	error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
383 	if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
384 		timeout_task->f &= ~DT_CALLOUT_ARMED;
385 		queue->tq_callouts--;
386 	}
387 	TQ_UNLOCK(queue);
388 
389 	if (pendp != NULL)
390 		*pendp = pending + pending1;
391 	return (error);
392 }
393 
394 void
395 taskqueue_drain(struct taskqueue *queue, struct task *task)
396 {
397 	TQ_LOCK(queue);
398 	while (task->ta_pending != 0 || task == queue->tq_running)
399 		TQ_SLEEP(queue, task, "-");
400 	TQ_UNLOCK(queue);
401 }
402 
403 void
404 taskqueue_drain_timeout(struct taskqueue *queue,
405     struct timeout_task *timeout_task)
406 {
407 
408 	callout_stop_sync(&timeout_task->c);
409 	taskqueue_drain(queue, &timeout_task->t);
410 }
411 
412 static void
413 taskqueue_swi_enqueue(void *context)
414 {
415 	setsofttq();
416 }
417 
418 static void
419 taskqueue_swi_run(void *arg, void *frame)
420 {
421 	taskqueue_run(taskqueue_swi, 0);
422 }
423 
424 static void
425 taskqueue_swi_mp_run(void *arg, void *frame)
426 {
427 	taskqueue_run(taskqueue_swi_mp, 0);
428 }
429 
430 int
431 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri, int ncpu,
432 			const char *fmt, ...)
433 {
434 	__va_list ap;
435 	struct thread *td;
436 	struct taskqueue *tq;
437 	int i, error, cpu;
438 	char ktname[MAXCOMLEN];
439 
440 	if (count <= 0)
441 		return EINVAL;
442 
443 	tq = *tqp;
444 	cpu = ncpu;
445 
446 	__va_start(ap, fmt);
447 	kvsnprintf(ktname, MAXCOMLEN, fmt, ap);
448 	__va_end(ap);
449 
450 	tq->tq_threads = kmalloc(sizeof(struct thread *) * count, M_TASKQUEUE,
451 	    M_WAITOK | M_ZERO);
452 
453 	for (i = 0; i < count; i++) {
454 		/*
455 		 * If no specific cpu was specified and more than one thread
456 		 * is to be created, we distribute the threads amongst all
457 		 * cpus.
458 		 */
459 		if ((ncpu <= -1) && (count > 1))
460 			cpu = i%ncpus;
461 
462 		if (count == 1) {
463 			error = lwkt_create(taskqueue_thread_loop, tqp,
464 					    &tq->tq_threads[i], NULL,
465 					    TDF_NOSTART, cpu,
466 					    "%s", ktname);
467 		} else {
468 			error = lwkt_create(taskqueue_thread_loop, tqp,
469 					    &tq->tq_threads[i], NULL,
470 					    TDF_NOSTART, cpu,
471 					    "%s_%d", ktname, i);
472 		}
473 		if (error) {
474 			kprintf("%s: lwkt_create(%s): error %d", __func__,
475 			    ktname, error);
476 			tq->tq_threads[i] = NULL;
477 		} else {
478 			td = tq->tq_threads[i];
479 			lwkt_setpri_initial(td, pri);
480 			lwkt_schedule(td);
481 			tq->tq_tcount++;
482 		}
483 	}
484 
485 	return 0;
486 }
487 
488 void
489 taskqueue_thread_loop(void *arg)
490 {
491 	struct taskqueue **tqp, *tq;
492 
493 	tqp = arg;
494 	tq = *tqp;
495 	TQ_LOCK(tq);
496 	while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
497 		taskqueue_run(tq, 1);
498 		TQ_SLEEP(tq, tq, "tqthr");
499 	}
500 
501 	/* rendezvous with thread that asked us to terminate */
502 	tq->tq_tcount--;
503 	TQ_UNLOCK(tq);
504 	wakeup_one(tq->tq_threads);
505 	lwkt_exit();
506 }
507 
508 /* NOTE: tq must be locked */
509 void
510 taskqueue_thread_enqueue(void *context)
511 {
512 	struct taskqueue **tqp, *tq;
513 
514 	tqp = context;
515 	tq = *tqp;
516 
517 	/* Unlock spinlock before wakeup_one() */
518 	TQ_UNLOCK(tq);
519 	wakeup_one(tq);
520 	TQ_LOCK(tq);
521 }
522 
523 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
524 	 register_swi(SWI_TQ, taskqueue_swi_run, NULL, "swi_taskq", NULL, -1));
525 /*
526  * XXX: possibly use a different SWI_TQ_MP or so.
527  * related: sys/interrupt.h
528  * related: platform/XXX/isa/ipl_funcs.c
529  */
530 TASKQUEUE_DEFINE(swi_mp, taskqueue_swi_enqueue, 0,
531     register_swi_mp(SWI_TQ, taskqueue_swi_mp_run, NULL, "swi_mp_taskq", NULL,
532 		    -1));
533 
534 struct taskqueue *taskqueue_thread[MAXCPU];
535 
536 static void
537 taskqueue_init(void)
538 {
539 	int cpu;
540 
541 	lockinit(&taskqueue_queues_lock, "tqqueues", 0, 0);
542 	STAILQ_INIT(&taskqueue_queues);
543 
544 	for (cpu = 0; cpu < ncpus; cpu++) {
545 		taskqueue_thread[cpu] = taskqueue_create("thread", M_INTWAIT,
546 		    taskqueue_thread_enqueue, &taskqueue_thread[cpu]);
547 		taskqueue_start_threads(&taskqueue_thread[cpu], 1,
548 		    TDPRI_KERN_DAEMON, cpu, "taskq_cpu %d", cpu);
549 	}
550 }
551 
552 SYSINIT(taskqueueinit, SI_SUB_PRE_DRIVERS, SI_ORDER_ANY, taskqueue_init, NULL);
553