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: releng/8.2/sys/kern/subr_taskqueue.c 215190 2010-11-12 18:09:06Z mdf $");
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/lock.h>
37 #include <sys/malloc.h>
38 #include <sys/mutex.h>
39 #include <sys/proc.h>
40 #include <sys/sched.h>
41 #include <sys/taskqueue.h>
42 #include <sys/unistd.h>
43 #include <machine/stdarg.h>
44
45 static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
46 static void *taskqueue_giant_ih;
47 static void *taskqueue_ih;
48
49 struct taskqueue_busy {
50 struct task *tb_running;
51 TAILQ_ENTRY(taskqueue_busy) tb_link;
52 };
53
54 struct taskqueue {
55 STAILQ_HEAD(, task) tq_queue;
56 const char *tq_name;
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 };
66
67 #define TQ_FLAGS_ACTIVE (1 << 0)
68 #define TQ_FLAGS_BLOCKED (1 << 1)
69 #define TQ_FLAGS_PENDING (1 << 2)
70
71 static void taskqueue_run_locked(struct taskqueue *);
72
73 static __inline void
74 TQ_LOCK(struct taskqueue *tq)
75 {
76 if (tq->tq_spin)
77 mtx_lock_spin(&tq->tq_mutex);
78 else
79 mtx_lock(&tq->tq_mutex);
80 }
81
82 static __inline void
83 TQ_UNLOCK(struct taskqueue *tq)
84 {
85 if (tq->tq_spin)
86 mtx_unlock_spin(&tq->tq_mutex);
87 else
88 mtx_unlock(&tq->tq_mutex);
89 }
90
91 static __inline int
92 TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm,
93 int t)
94 {
95 if (tq->tq_spin)
96 return (msleep_spin(p, m, wm, t));
97 return (msleep(p, m, pri, wm, t));
98 }
99
100 static struct taskqueue *
101 _taskqueue_create(const char *name, int mflags,
102 taskqueue_enqueue_fn enqueue, void *context,
103 int mtxflags, const char *mtxname)
104 {
105 struct taskqueue *queue;
106
107 queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
108 if (!queue)
109 return NULL;
110
111 STAILQ_INIT(&queue->tq_queue);
112 TAILQ_INIT(&queue->tq_active);
113 queue->tq_name = name;
114 queue->tq_enqueue = enqueue;
115 queue->tq_context = context;
116 queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
117 queue->tq_flags |= TQ_FLAGS_ACTIVE;
118 mtx_init(&queue->tq_mutex, mtxname, NULL, mtxflags);
119
120 return queue;
121 }
122
123 struct taskqueue *
124 taskqueue_create(const char *name, int mflags,
125 taskqueue_enqueue_fn enqueue, void *context)
126 {
127 return _taskqueue_create(name, mflags, enqueue, context,
128 MTX_DEF, "taskqueue");
129 }
130
131 /*
132 * Signal a taskqueue thread to terminate.
133 */
134 static void
135 taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
136 {
137
138 while (tq->tq_tcount > 0) {
139 wakeup(tq);
140 TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0);
141 }
142 }
143
144 void
145 taskqueue_free(struct taskqueue *queue)
146 {
147
148 TQ_LOCK(queue);
149 queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
150 taskqueue_run_locked(queue);
151 taskqueue_terminate(queue->tq_threads, queue);
152 KASSERT(TAILQ_EMPTY(&queue->tq_active), ("Tasks still running?"));
153 mtx_destroy(&queue->tq_mutex);
154 free(queue->tq_threads, M_TASKQUEUE);
155 free(queue, M_TASKQUEUE);
156 }
157
158 int
159 taskqueue_enqueue(struct taskqueue *queue, struct task *task)
160 {
161 struct task *ins;
162 struct task *prev;
163
164 TQ_LOCK(queue);
165
166 /*
167 * Count multiple enqueues.
168 */
169 if (task->ta_pending) {
170 task->ta_pending++;
171 TQ_UNLOCK(queue);
172 return 0;
173 }
174
175 /*
176 * Optimise the case when all tasks have the same priority.
177 */
178 prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
179 if (!prev || prev->ta_priority >= task->ta_priority) {
180 STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
181 } else {
182 prev = NULL;
183 for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
184 prev = ins, ins = STAILQ_NEXT(ins, ta_link))
185 if (ins->ta_priority < task->ta_priority)
186 break;
187
188 if (prev)
189 STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
190 else
191 STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
192 }
193
194 task->ta_pending = 1;
195 if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0)
196 queue->tq_enqueue(queue->tq_context);
197 else
198 queue->tq_flags |= TQ_FLAGS_PENDING;
199
200 TQ_UNLOCK(queue);
201
202 return 0;
203 }
204
205 void
206 taskqueue_block(struct taskqueue *queue)
207 {
208
209 TQ_LOCK(queue);
210 queue->tq_flags |= TQ_FLAGS_BLOCKED;
211 TQ_UNLOCK(queue);
212 }
213
214 void
215 taskqueue_unblock(struct taskqueue *queue)
216 {
217
218 TQ_LOCK(queue);
219 queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
220 if (queue->tq_flags & TQ_FLAGS_PENDING) {
221 queue->tq_flags &= ~TQ_FLAGS_PENDING;
222 queue->tq_enqueue(queue->tq_context);
223 }
224 TQ_UNLOCK(queue);
225 }
226
227 static void
228 taskqueue_run_locked(struct taskqueue *queue)
229 {
230 struct taskqueue_busy tb;
231 struct task *task;
232 int pending;
233
234 mtx_assert(&queue->tq_mutex, MA_OWNED);
235 tb.tb_running = NULL;
236 TAILQ_INSERT_TAIL(&queue->tq_active, &tb, tb_link);
237
238 while (STAILQ_FIRST(&queue->tq_queue)) {
239 /*
240 * Carefully remove the first task from the queue and
241 * zero its pending count.
242 */
243 task = STAILQ_FIRST(&queue->tq_queue);
244 STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
245 pending = task->ta_pending;
246 task->ta_pending = 0;
247 tb.tb_running = task;
248 TQ_UNLOCK(queue);
249
250 task->ta_func(task->ta_context, pending);
251
252 TQ_LOCK(queue);
253 tb.tb_running = NULL;
254 wakeup(task);
255 }
256 TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
257 }
258
259 void
260 taskqueue_run(struct taskqueue *queue)
261 {
262
263 TQ_LOCK(queue);
264 taskqueue_run_locked(queue);
265 TQ_UNLOCK(queue);
266 }
267
268 static int
269 task_is_running(struct taskqueue *queue, struct task *task)
270 {
271 struct taskqueue_busy *tb;
272
273 mtx_assert(&queue->tq_mutex, MA_OWNED);
274 TAILQ_FOREACH(tb, &queue->tq_active, tb_link) {
275 if (tb->tb_running == task)
276 return (1);
277 }
278 return (0);
279 }
280
281 void
282 taskqueue_drain(struct taskqueue *queue, struct task *task)
283 {
284 if (queue->tq_spin) { /* XXX */
285 mtx_lock_spin(&queue->tq_mutex);
286 while (task->ta_pending != 0 || task_is_running(queue, task))
287 msleep_spin(task, &queue->tq_mutex, "-", 0);
288 mtx_unlock_spin(&queue->tq_mutex);
289 } else {
290 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
291
292 mtx_lock(&queue->tq_mutex);
293 while (task->ta_pending != 0 || task_is_running(queue, task))
294 msleep(task, &queue->tq_mutex, PWAIT, "-", 0);
295 mtx_unlock(&queue->tq_mutex);
296 }
297 }
298
299 static void
300 taskqueue_swi_enqueue(void *context)
301 {
302 swi_sched(taskqueue_ih, 0);
303 }
304
305 static void
306 taskqueue_swi_run(void *dummy)
307 {
308 taskqueue_run(taskqueue_swi);
309 }
310
311 static void
312 taskqueue_swi_giant_enqueue(void *context)
313 {
314 swi_sched(taskqueue_giant_ih, 0);
315 }
316
317 static void
318 taskqueue_swi_giant_run(void *dummy)
319 {
320 taskqueue_run(taskqueue_swi_giant);
321 }
322
323 int
324 taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
325 const char *name, ...)
326 {
327 va_list ap;
328 struct thread *td;
329 struct taskqueue *tq;
330 int i, error;
331 char ktname[MAXCOMLEN + 1];
332
333 if (count <= 0)
334 return (EINVAL);
335
336 tq = *tqp;
337
338 va_start(ap, name);
339 vsnprintf(ktname, sizeof(ktname), name, ap);
340 va_end(ap);
341
342 tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
343 M_NOWAIT | M_ZERO);
344 if (tq->tq_threads == NULL) {
345 printf("%s: no memory for %s threads\n", __func__, ktname);
346 return (ENOMEM);
347 }
348
349 for (i = 0; i < count; i++) {
350 if (count == 1)
351 error = kthread_add(taskqueue_thread_loop, tqp, NULL,
352 &tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname);
353 else
354 error = kthread_add(taskqueue_thread_loop, tqp, NULL,
355 &tq->tq_threads[i], RFSTOPPED, 0,
356 "%s_%d", ktname, i);
357 if (error) {
358 /* should be ok to continue, taskqueue_free will dtrt */
359 printf("%s: kthread_add(%s): error %d", __func__,
360 ktname, error);
361 tq->tq_threads[i] = NULL; /* paranoid */
362 } else
363 tq->tq_tcount++;
364 }
365 for (i = 0; i < count; i++) {
366 if (tq->tq_threads[i] == NULL)
367 continue;
368 td = tq->tq_threads[i];
369 thread_lock(td);
370 sched_prio(td, pri);
371 sched_add(td, SRQ_BORING);
372 thread_unlock(td);
373 }
374
375 return (0);
376 }
377
378 void
379 taskqueue_thread_loop(void *arg)
380 {
381 struct taskqueue **tqp, *tq;
382
383 tqp = arg;
384 tq = *tqp;
385 TQ_LOCK(tq);
386 while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
387 taskqueue_run_locked(tq);
388 /*
389 * Because taskqueue_run() can drop tq_mutex, we need to
390 * check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
391 * meantime, which means we missed a wakeup.
392 */
393 if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
394 break;
395 TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
396 }
397
398 /* rendezvous with thread that asked us to terminate */
399 tq->tq_tcount--;
400 wakeup_one(tq->tq_threads);
401 TQ_UNLOCK(tq);
402 kthread_exit();
403 }
404
405 void
406 taskqueue_thread_enqueue(void *context)
407 {
408 struct taskqueue **tqp, *tq;
409
410 tqp = context;
411 tq = *tqp;
412
413 mtx_assert(&tq->tq_mutex, MA_OWNED);
414 wakeup_one(tq);
415 }
416
417 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
418 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
419 INTR_MPSAFE, &taskqueue_ih));
420
421 TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
422 swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
423 NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
424
425 TASKQUEUE_DEFINE_THREAD(thread);
426
427 struct taskqueue *
428 taskqueue_create_fast(const char *name, int mflags,
429 taskqueue_enqueue_fn enqueue, void *context)
430 {
431 return _taskqueue_create(name, mflags, enqueue, context,
432 MTX_SPIN, "fast_taskqueue");
433 }
434
435 /* NB: for backwards compatibility */
436 int
437 taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
438 {
439 return taskqueue_enqueue(queue, task);
440 }
441
442 static void *taskqueue_fast_ih;
443
444 static void
445 taskqueue_fast_enqueue(void *context)
446 {
447 swi_sched(taskqueue_fast_ih, 0);
448 }
449
450 static void
451 taskqueue_fast_run(void *dummy)
452 {
453 taskqueue_run(taskqueue_fast);
454 }
455
456 TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
457 swi_add(NULL, "Fast task queue", taskqueue_fast_run, NULL,
458 SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
459
460 int
461 taskqueue_member(struct taskqueue *queue, struct thread *td)
462 {
463 int i, j, ret = 0;
464
465 TQ_LOCK(queue);
466 for (i = 0, j = 0; ; i++) {
467 if (queue->tq_threads[i] == NULL)
468 continue;
469 if (queue->tq_threads[i] == td) {
470 ret = 1;
471 break;
472 }
473 if (++j >= queue->tq_tcount)
474 break;
475 }
476 TQ_UNLOCK(queue);
477 return (ret);
478 }
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