xref: /dragonfly/sys/kern/subr_taskqueue.c (revision 279dd846) 
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 	taskqueue_enqueue_fn	tq_enqueue;
55 	void			*tq_context;
56 
57 	struct task		*tq_running;
58 	struct spinlock		tq_lock;
59 	struct thread		**tq_threads;
60 	int			tq_tcount;
61 	int			tq_flags;
62 	int			tq_callouts;
63 };
64 
65 #define	TQ_FLAGS_ACTIVE		(1 << 0)
66 #define	TQ_FLAGS_BLOCKED	(1 << 1)
67 #define	TQ_FLAGS_PENDING	(1 << 2)
68 
69 #define	DT_CALLOUT_ARMED	(1 << 0)
70 
71 void
72 _timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
73     int priority, task_fn_t func, void *context)
74 {
75 
76 	TASK_INIT(&timeout_task->t, priority, func, context);
77 	callout_init(&timeout_task->c);
78 	timeout_task->q = queue;
79 	timeout_task->f = 0;
80 }
81 
82 static void taskqueue_run(struct taskqueue *queue, int lock_held);
83 
84 static __inline void
85 TQ_LOCK_INIT(struct taskqueue *tq)
86 {
87 	spin_init(&tq->tq_lock, "tqlock");
88 }
89 
90 static __inline void
91 TQ_LOCK_UNINIT(struct taskqueue *tq)
92 {
93 	spin_uninit(&tq->tq_lock);
94 }
95 
96 static __inline void
97 TQ_LOCK(struct taskqueue *tq)
98 {
99 	spin_lock(&tq->tq_lock);
100 }
101 
102 static __inline void
103 TQ_UNLOCK(struct taskqueue *tq)
104 {
105 	spin_unlock(&tq->tq_lock);
106 }
107 
108 static __inline void
109 TQ_SLEEP(struct taskqueue *tq, void *ident, const char *wmesg)
110 {
111 	ssleep(ident, &tq->tq_lock, 0, wmesg, 0);
112 }
113 
114 struct taskqueue *
115 taskqueue_create(const char *name, int mflags,
116 		 taskqueue_enqueue_fn enqueue, void *context)
117 {
118 	struct taskqueue *queue;
119 
120 	queue = kmalloc(sizeof(*queue), M_TASKQUEUE, mflags | M_ZERO);
121 	if (!queue)
122 		return NULL;
123 	STAILQ_INIT(&queue->tq_queue);
124 	queue->tq_name = name;
125 	queue->tq_enqueue = enqueue;
126 	queue->tq_context = context;
127 	queue->tq_flags |= TQ_FLAGS_ACTIVE;
128 	TQ_LOCK_INIT(queue);
129 
130 	lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
131 	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
132 	lockmgr(&taskqueue_queues_lock, LK_RELEASE);
133 
134 	return queue;
135 }
136 
137 static void
138 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
139 {
140 	while(tq->tq_tcount > 0) {
141 		wakeup(tq);
142 		TQ_SLEEP(tq, pp, "taskqueue_terminate");
143 	}
144 }
145 
146 void
147 taskqueue_free(struct taskqueue *queue)
148 {
149 	TQ_LOCK(queue);
150 	queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
151 	taskqueue_run(queue, 1);
152 	taskqueue_terminate(queue->tq_threads, queue);
153 	TQ_UNLOCK(queue);
154 
155 	lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
156 	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
157 	lockmgr(&taskqueue_queues_lock, LK_RELEASE);
158 
159 	TQ_LOCK_UNINIT(queue);
160 
161 	kfree(queue, M_TASKQUEUE);
162 }
163 
164 struct taskqueue *
165 taskqueue_find(const char *name)
166 {
167 	struct taskqueue *queue;
168 
169 	lockmgr(&taskqueue_queues_lock, LK_EXCLUSIVE);
170 	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
171 		if (!strcmp(queue->tq_name, name)) {
172 			lockmgr(&taskqueue_queues_lock, LK_RELEASE);
173 			return queue;
174 		}
175 	}
176 	lockmgr(&taskqueue_queues_lock, LK_RELEASE);
177 	return NULL;
178 }
179 
180 /*
181  * NOTE!  If using the per-cpu taskqueues ``taskqueue_thread[mycpuid]'',
182  * be sure NOT TO SHARE the ``task'' between CPUs.  TASKS ARE NOT LOCKED.
183  * So either use a throwaway task which will only be enqueued once, or
184  * use one task per CPU!
185  */
186 static int
187 taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
188 {
189 	struct task *ins;
190 	struct task *prev;
191 
192 	/*
193 	 * Don't allow new tasks on a queue which is being freed.
194 	 */
195 	if ((queue->tq_flags & TQ_FLAGS_ACTIVE) == 0)
196 		return EPIPE;
197 
198 	/*
199 	 * Count multiple enqueues.
200 	 */
201 	if (task->ta_pending) {
202 		task->ta_pending++;
203 		return 0;
204 	}
205 
206 	/*
207 	 * Optimise the case when all tasks have the same priority.
208 	 */
209 	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
210 	if (!prev || prev->ta_priority >= task->ta_priority) {
211 		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
212 	} else {
213 		prev = NULL;
214 		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
215 		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
216 			if (ins->ta_priority < task->ta_priority)
217 				break;
218 
219 		if (prev)
220 			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
221 		else
222 			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
223 	}
224 
225 	task->ta_pending = 1;
226 	if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0) {
227 		if (queue->tq_enqueue)
228 			queue->tq_enqueue(queue->tq_context);
229 	} else {
230 		queue->tq_flags |= TQ_FLAGS_PENDING;
231 	}
232 
233 	return 0;
234 }
235 
236 int
237 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
238 {
239 	int res;
240 
241 	TQ_LOCK(queue);
242 	res = taskqueue_enqueue_locked(queue, task);
243 	TQ_UNLOCK(queue);
244 
245 	return (res);
246 }
247 
248 static void
249 taskqueue_timeout_func(void *arg)
250 {
251 	struct taskqueue *queue;
252 	struct timeout_task *timeout_task;
253 
254 	timeout_task = arg;
255 	queue = timeout_task->q;
256 	KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
257 	timeout_task->f &= ~DT_CALLOUT_ARMED;
258 	queue->tq_callouts--;
259 	taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
260 }
261 
262 int
263 taskqueue_enqueue_timeout(struct taskqueue *queue,
264     struct timeout_task *timeout_task, int ticks)
265 {
266 	int res;
267 
268 	TQ_LOCK(queue);
269 	KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
270 		("Migrated queue"));
271 	timeout_task->q = queue;
272 	res = timeout_task->t.ta_pending;
273 	if (ticks == 0) {
274 		taskqueue_enqueue_locked(queue, &timeout_task->t);
275 		TQ_UNLOCK(queue);
276 	} else {
277 		if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
278 			res++;
279 		} else {
280 			queue->tq_callouts++;
281 			timeout_task->f |= DT_CALLOUT_ARMED;
282 		}
283 		TQ_UNLOCK(queue);
284 		callout_reset(&timeout_task->c, ticks, taskqueue_timeout_func,
285 			      timeout_task);
286 	}
287 	return (res);
288 }
289 
290 void
291 taskqueue_block(struct taskqueue *queue)
292 {
293 	TQ_LOCK(queue);
294 	queue->tq_flags |= TQ_FLAGS_BLOCKED;
295 	TQ_UNLOCK(queue);
296 }
297 
298 void
299 taskqueue_unblock(struct taskqueue *queue)
300 {
301 	TQ_LOCK(queue);
302 	queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
303 	if (queue->tq_flags & TQ_FLAGS_PENDING) {
304 		queue->tq_flags &= ~TQ_FLAGS_PENDING;
305 		if (queue->tq_enqueue)
306 			queue->tq_enqueue(queue->tq_context);
307 	}
308 	TQ_UNLOCK(queue);
309 }
310 
311 static void
312 taskqueue_run(struct taskqueue *queue, int lock_held)
313 {
314 	struct task *task;
315 	int pending;
316 
317 	if (lock_held == 0)
318 		TQ_LOCK(queue);
319 	while (STAILQ_FIRST(&queue->tq_queue)) {
320 		/*
321 		 * Carefully remove the first task from the queue and
322 		 * zero its pending count.
323 		 */
324 		task = STAILQ_FIRST(&queue->tq_queue);
325 		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
326 		pending = task->ta_pending;
327 		task->ta_pending = 0;
328 		queue->tq_running = task;
329 
330 		TQ_UNLOCK(queue);
331 		task->ta_func(task->ta_context, pending);
332 		queue->tq_running = NULL;
333 		wakeup(task);
334 		TQ_LOCK(queue);
335 	}
336 	if (lock_held == 0)
337 		TQ_UNLOCK(queue);
338 }
339 
340 static int
341 taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
342     u_int *pendp)
343 {
344 
345 	if (task->ta_pending > 0)
346 		STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
347 	if (pendp != NULL)
348 		*pendp = task->ta_pending;
349 	task->ta_pending = 0;
350 	return (task == queue->tq_running ? EBUSY : 0);
351 }
352 
353 int
354 taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
355 {
356 	int error;
357 
358 	TQ_LOCK(queue);
359 	error = taskqueue_cancel_locked(queue, task, pendp);
360 	TQ_UNLOCK(queue);
361 
362 	return (error);
363 }
364 
365 int
366 taskqueue_cancel_timeout(struct taskqueue *queue,
367 			 struct timeout_task *timeout_task, u_int *pendp)
368 {
369 	u_int pending, pending1;
370 	int error;
371 
372 	pending = !!callout_stop(&timeout_task->c);
373 	TQ_LOCK(queue);
374 	error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
375 	if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
376 		timeout_task->f &= ~DT_CALLOUT_ARMED;
377 		queue->tq_callouts--;
378 	}
379 	TQ_UNLOCK(queue);
380 
381 	if (pendp != NULL)
382 		*pendp = pending + pending1;
383 	return (error);
384 }
385 
386 void
387 taskqueue_drain(struct taskqueue *queue, struct task *task)
388 {
389 	TQ_LOCK(queue);
390 	while (task->ta_pending != 0 || task == queue->tq_running)
391 		TQ_SLEEP(queue, task, "-");
392 	TQ_UNLOCK(queue);
393 }
394 
395 void
396 taskqueue_drain_timeout(struct taskqueue *queue,
397     struct timeout_task *timeout_task)
398 {
399 
400 	callout_stop_sync(&timeout_task->c);
401 	taskqueue_drain(queue, &timeout_task->t);
402 }
403 
404 static void
405 taskqueue_swi_enqueue(void *context)
406 {
407 	setsofttq();
408 }
409 
410 static void
411 taskqueue_swi_run(void *arg, void *frame)
412 {
413 	taskqueue_run(taskqueue_swi, 0);
414 }
415 
416 static void
417 taskqueue_swi_mp_run(void *arg, void *frame)
418 {
419 	taskqueue_run(taskqueue_swi_mp, 0);
420 }
421 
422 int
423 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri, int ncpu,
424 			const char *fmt, ...)
425 {
426 	__va_list ap;
427 	struct thread *td;
428 	struct taskqueue *tq;
429 	int i, error, cpu;
430 	char ktname[MAXCOMLEN];
431 
432 	if (count <= 0)
433 		return EINVAL;
434 
435 	tq = *tqp;
436 	cpu = ncpu;
437 
438 	__va_start(ap, fmt);
439 	kvsnprintf(ktname, MAXCOMLEN, fmt, ap);
440 	__va_end(ap);
441 
442 	tq->tq_threads = kmalloc(sizeof(struct thread *) * count, M_TASKQUEUE,
443 	    M_WAITOK | M_ZERO);
444 
445 	for (i = 0; i < count; i++) {
446 		/*
447 		 * If no specific cpu was specified and more than one thread
448 		 * is to be created, we distribute the threads amongst all
449 		 * cpus.
450 		 */
451 		if ((ncpu <= -1) && (count > 1))
452 			cpu = i%ncpus;
453 
454 		if (count == 1) {
455 			error = lwkt_create(taskqueue_thread_loop, tqp,
456 					    &tq->tq_threads[i], NULL,
457 					    TDF_NOSTART, cpu,
458 					    "%s", ktname);
459 		} else {
460 			error = lwkt_create(taskqueue_thread_loop, tqp,
461 					    &tq->tq_threads[i], NULL,
462 					    TDF_NOSTART, cpu,
463 					    "%s_%d", ktname, i);
464 		}
465 		if (error) {
466 			kprintf("%s: lwkt_create(%s): error %d", __func__,
467 			    ktname, error);
468 			tq->tq_threads[i] = NULL;
469 		} else {
470 			td = tq->tq_threads[i];
471 			lwkt_setpri_initial(td, pri);
472 			lwkt_schedule(td);
473 			tq->tq_tcount++;
474 		}
475 	}
476 
477 	return 0;
478 }
479 
480 void
481 taskqueue_thread_loop(void *arg)
482 {
483 	struct taskqueue **tqp, *tq;
484 
485 	tqp = arg;
486 	tq = *tqp;
487 	TQ_LOCK(tq);
488 	while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
489 		taskqueue_run(tq, 1);
490 		TQ_SLEEP(tq, tq, "tqthr");
491 	}
492 
493 	/* rendezvous with thread that asked us to terminate */
494 	tq->tq_tcount--;
495 	TQ_UNLOCK(tq);
496 	wakeup_one(tq->tq_threads);
497 	lwkt_exit();
498 }
499 
500 void
501 taskqueue_thread_enqueue(void *context)
502 {
503 	struct taskqueue **tqp, *tq;
504 
505 	tqp = context;
506 	tq = *tqp;
507 
508 	wakeup_one(tq);
509 }
510 
511 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
512 	 register_swi(SWI_TQ, taskqueue_swi_run, NULL, "swi_taskq", NULL, -1));
513 /*
514  * XXX: possibly use a different SWI_TQ_MP or so.
515  * related: sys/interrupt.h
516  * related: platform/XXX/isa/ipl_funcs.c
517  */
518 TASKQUEUE_DEFINE(swi_mp, taskqueue_swi_enqueue, 0,
519     register_swi_mp(SWI_TQ, taskqueue_swi_mp_run, NULL, "swi_mp_taskq", NULL,
520 		    -1));
521 
522 struct taskqueue *taskqueue_thread[MAXCPU];
523 
524 static void
525 taskqueue_init(void)
526 {
527 	int cpu;
528 
529 	lockinit(&taskqueue_queues_lock, "tqqueues", 0, 0);
530 	STAILQ_INIT(&taskqueue_queues);
531 
532 	for (cpu = 0; cpu < ncpus; cpu++) {
533 		taskqueue_thread[cpu] = taskqueue_create("thread", M_INTWAIT,
534 		    taskqueue_thread_enqueue, &taskqueue_thread[cpu]);
535 		taskqueue_start_threads(&taskqueue_thread[cpu], 1,
536 		    TDPRI_KERN_DAEMON, cpu, "taskq_cpu %d", cpu);
537 	}
538 }
539 
540 SYSINIT(taskqueueinit, SI_SUB_PRE_DRIVERS, SI_ORDER_ANY, taskqueue_init, NULL);
541