summaryrefslogtreecommitdiffstats
path: root/sys/kern/subr_taskqueue.c
blob: c3ddb5f387655f95b0b69f873d95c0f1153ac33f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
/*-
 * Copyright (c) 2000 Doug Rabson
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/interrupt.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sched.h>
#include <sys/taskqueue.h>
#include <sys/unistd.h>
#include <machine/stdarg.h>

static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
static void	*taskqueue_giant_ih;
static void	*taskqueue_ih;
static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
static struct mtx taskqueue_queues_mutex;

struct taskqueue {
	STAILQ_ENTRY(taskqueue)	tq_link;
	STAILQ_HEAD(, task)	tq_queue;
	const char		*tq_name;
	taskqueue_enqueue_fn	tq_enqueue;
	void			*tq_context;
	struct task		*tq_running;
	struct mtx		tq_mutex;
	struct proc		**tq_pproc;
	int			tq_pcount;
	int			tq_spin;
	int			tq_flags;
};

#define	TQ_FLAGS_ACTIVE		(1 << 0)

static __inline void
TQ_LOCK(struct taskqueue *tq)
{
	if (tq->tq_spin)
		mtx_lock_spin(&tq->tq_mutex);
	else
		mtx_lock(&tq->tq_mutex);
}

static __inline void
TQ_UNLOCK(struct taskqueue *tq)
{
	if (tq->tq_spin)
		mtx_unlock_spin(&tq->tq_mutex);
	else
		mtx_unlock(&tq->tq_mutex);
}

static void	init_taskqueue_list(void *data);

static __inline int
TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm,
    int t)
{
	if (tq->tq_spin)
		return (msleep_spin(p, m, wm, t));
	return (msleep(p, m, pri, wm, t));
}

static void
init_taskqueue_list(void *data __unused)
{

	mtx_init(&taskqueue_queues_mutex, "taskqueue list", NULL, MTX_DEF);
	STAILQ_INIT(&taskqueue_queues);
}
SYSINIT(taskqueue_list, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_taskqueue_list,
    NULL);

static struct taskqueue *
_taskqueue_create(const char *name, int mflags,
		 taskqueue_enqueue_fn enqueue, void *context,
		 int mtxflags, const char *mtxname)
{
	struct taskqueue *queue;

	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
	if (!queue)
		return 0;

	STAILQ_INIT(&queue->tq_queue);
	queue->tq_name = name;
	queue->tq_enqueue = enqueue;
	queue->tq_context = context;
	queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
	queue->tq_flags |= TQ_FLAGS_ACTIVE;
	mtx_init(&queue->tq_mutex, mtxname, NULL, mtxflags);

	mtx_lock(&taskqueue_queues_mutex);
	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
	mtx_unlock(&taskqueue_queues_mutex);

	return queue;
}

struct taskqueue *
taskqueue_create(const char *name, int mflags,
		 taskqueue_enqueue_fn enqueue, void *context)
{
	return _taskqueue_create(name, mflags, enqueue, context,
			MTX_DEF, "taskqueue");
}

/*
 * Signal a taskqueue thread to terminate.
 */
static void
taskqueue_terminate(struct proc **pp, struct taskqueue *tq)
{

	while (tq->tq_pcount > 0) {
		wakeup(tq);
		TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0);
	}
}

void
taskqueue_free(struct taskqueue *queue)
{

	mtx_lock(&taskqueue_queues_mutex);
	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
	mtx_unlock(&taskqueue_queues_mutex);

	TQ_LOCK(queue);
	queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
	taskqueue_run(queue);
	taskqueue_terminate(queue->tq_pproc, queue);
	mtx_destroy(&queue->tq_mutex);
	free(queue->tq_pproc, M_TASKQUEUE);
	free(queue, M_TASKQUEUE);
}

/*
 * Returns with the taskqueue locked.
 */
struct taskqueue *
taskqueue_find(const char *name)
{
	struct taskqueue *queue;

	mtx_lock(&taskqueue_queues_mutex);
	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
		if (strcmp(queue->tq_name, name) == 0) {
			TQ_LOCK(queue);
			mtx_unlock(&taskqueue_queues_mutex);
			return queue;
		}
	}
	mtx_unlock(&taskqueue_queues_mutex);
	return NULL;
}

int
taskqueue_enqueue(struct taskqueue *queue, struct task *task)
{
	struct task *ins;
	struct task *prev;

	TQ_LOCK(queue);

	/*
	 * Count multiple enqueues.
	 */
	if (task->ta_pending) {
		task->ta_pending++;
		TQ_UNLOCK(queue);
		return 0;
	}

	/*
	 * Optimise the case when all tasks have the same priority.
	 */
	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
	if (!prev || prev->ta_priority >= task->ta_priority) {
		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
	} else {
		prev = 0;
		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
			if (ins->ta_priority < task->ta_priority)
				break;

		if (prev)
			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
		else
			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
	}

	task->ta_pending = 1;
	queue->tq_enqueue(queue->tq_context);

	TQ_UNLOCK(queue);

	return 0;
}

void
taskqueue_run(struct taskqueue *queue)
{
	struct task *task;
	int owned, pending;

	owned = mtx_owned(&queue->tq_mutex);
	if (!owned)
		TQ_LOCK(queue);
	while (STAILQ_FIRST(&queue->tq_queue)) {
		/*
		 * Carefully remove the first task from the queue and
		 * zero its pending count.
		 */
		task = STAILQ_FIRST(&queue->tq_queue);
		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
		pending = task->ta_pending;
		task->ta_pending = 0;
		queue->tq_running = task;
		TQ_UNLOCK(queue);

		task->ta_func(task->ta_context, pending);

		TQ_LOCK(queue);
		queue->tq_running = NULL;
		wakeup(task);
	}

	/*
	 * For compatibility, unlock on return if the queue was not locked
	 * on entry, although this opens a race window.
	 */
	if (!owned)
		TQ_UNLOCK(queue);
}

void
taskqueue_drain(struct taskqueue *queue, struct task *task)
{
	if (queue->tq_spin) {		/* XXX */
		mtx_lock_spin(&queue->tq_mutex);
		while (task->ta_pending != 0 || task == queue->tq_running)
			msleep_spin(task, &queue->tq_mutex, "-", 0);
		mtx_unlock_spin(&queue->tq_mutex);
	} else {
		WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);

		mtx_lock(&queue->tq_mutex);
		while (task->ta_pending != 0 || task == queue->tq_running)
			msleep(task, &queue->tq_mutex, PWAIT, "-", 0);
		mtx_unlock(&queue->tq_mutex);
	}
}

static void
taskqueue_swi_enqueue(void *context)
{
	swi_sched(taskqueue_ih, 0);
}

static void
taskqueue_swi_run(void *dummy)
{
	taskqueue_run(taskqueue_swi);
}

static void
taskqueue_swi_giant_enqueue(void *context)
{
	swi_sched(taskqueue_giant_ih, 0);
}

static void
taskqueue_swi_giant_run(void *dummy)
{
	taskqueue_run(taskqueue_swi_giant);
}

int
taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
			const char *name, ...)
{
	va_list ap;
	struct taskqueue *tq;
	struct thread *td;
	char ktname[MAXCOMLEN];
	int i, error;

	if (count <= 0)
		return (EINVAL);
	tq = *tqp;

	va_start(ap, name);
	vsnprintf(ktname, MAXCOMLEN, name, ap);
	va_end(ap);

	tq->tq_pproc = malloc(sizeof(struct proc *) * count, M_TASKQUEUE,
	    M_NOWAIT | M_ZERO);
	if (tq->tq_pproc == NULL) {
		printf("%s: no memory for %s threads\n", __func__, ktname);
		return (ENOMEM);
	}

	for (i = 0; i < count; i++) {
		if (count == 1)
			error = kproc_create(taskqueue_thread_loop, tqp,
			    &tq->tq_pproc[i], RFSTOPPED, 0, ktname);
		else
			error = kproc_create(taskqueue_thread_loop, tqp,
			    &tq->tq_pproc[i], RFSTOPPED, 0, "%s_%d", ktname, i);
		if (error) {
			/* should be ok to continue, taskqueue_free will dtrt */
			printf("%s: kproc_create(%s): error %d",
				__func__, ktname, error);
			tq->tq_pproc[i] = NULL;		/* paranoid */
		} else
			tq->tq_pcount++;
	}
	for (i = 0; i < count; i++) {
		if (tq->tq_pproc[i] == NULL)
			continue;
		td = FIRST_THREAD_IN_PROC(tq->tq_pproc[i]);
		thread_lock(td);
		sched_prio(td, pri);
		sched_add(td, SRQ_BORING);
		thread_unlock(td);
	}

	return (0);
}

void
taskqueue_thread_loop(void *arg)
{
	struct taskqueue **tqp, *tq;

	tqp = arg;
	tq = *tqp;
	TQ_LOCK(tq);
	do {
		taskqueue_run(tq);
		TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
	} while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0);

	/* rendezvous with thread that asked us to terminate */
	tq->tq_pcount--;
	wakeup_one(tq->tq_pproc);
	TQ_UNLOCK(tq);
	kproc_exit(0);
}

void
taskqueue_thread_enqueue(void *context)
{
	struct taskqueue **tqp, *tq;

	tqp = context;
	tq = *tqp;

	mtx_assert(&tq->tq_mutex, MA_OWNED);
	wakeup_one(tq);
}

TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
		 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
		     INTR_MPSAFE, &taskqueue_ih)); 

TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, 0,
		 swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
		     NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih)); 

TASKQUEUE_DEFINE_THREAD(thread);

struct taskqueue *
taskqueue_create_fast(const char *name, int mflags,
		 taskqueue_enqueue_fn enqueue, void *context)
{
	return _taskqueue_create(name, mflags, enqueue, context,
			MTX_SPIN, "fast_taskqueue");
}

/* NB: for backwards compatibility */
int
taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
{
	return taskqueue_enqueue(queue, task);
}

static void	*taskqueue_fast_ih;

static void
taskqueue_fast_enqueue(void *context)
{
	swi_sched(taskqueue_fast_ih, 0);
}

static void
taskqueue_fast_run(void *dummy)
{
	taskqueue_run(taskqueue_fast);
}

TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, 0,
	swi_add(NULL, "Fast task queue", taskqueue_fast_run, NULL,
	SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
OpenPOWER on IntegriCloud