subr_taskqueue.c revision 116182 
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: head/sys/kern/subr_taskqueue.c 116182 2003-06-11 00:56:59Z obrien $");
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/lock.h>
36#include <sys/malloc.h>
37#include <sys/mutex.h>
38#include <sys/taskqueue.h>
39
40static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
41
42static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
43
44static void	*taskqueue_ih;
45static void	*taskqueue_giant_ih;
46static struct mtx taskqueue_queues_mutex;
47
48struct taskqueue {
49	STAILQ_ENTRY(taskqueue)	tq_link;
50	STAILQ_HEAD(, task)	tq_queue;
51	const char		*tq_name;
52	taskqueue_enqueue_fn	tq_enqueue;
53	void			*tq_context;
54	int			tq_draining;
55	struct mtx		tq_mutex;
56};
57
58static void	init_taskqueue_list(void *data);
59
60static void
61init_taskqueue_list(void *data __unused)
62{
63
64	mtx_init(&taskqueue_queues_mutex, "taskqueue list", NULL, MTX_DEF);
65	STAILQ_INIT(&taskqueue_queues);
66}
67SYSINIT(taskqueue_list, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_taskqueue_list,
68    NULL);
69
70struct taskqueue *
71taskqueue_create(const char *name, int mflags,
72		 taskqueue_enqueue_fn enqueue, void *context)
73{
74	struct taskqueue *queue;
75
76	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
77	if (!queue)
78		return 0;
79
80	STAILQ_INIT(&queue->tq_queue);
81	queue->tq_name = name;
82	queue->tq_enqueue = enqueue;
83	queue->tq_context = context;
84	queue->tq_draining = 0;
85	mtx_init(&queue->tq_mutex, "taskqueue", NULL, MTX_DEF);
86
87	mtx_lock(&taskqueue_queues_mutex);
88	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
89	mtx_unlock(&taskqueue_queues_mutex);
90
91	return queue;
92}
93
94void
95taskqueue_free(struct taskqueue *queue)
96{
97
98	mtx_lock(&queue->tq_mutex);
99	KASSERT(queue->tq_draining == 0, ("free'ing a draining taskqueue"));
100	queue->tq_draining = 1;
101	mtx_unlock(&queue->tq_mutex);
102
103	taskqueue_run(queue);
104
105	mtx_lock(&taskqueue_queues_mutex);
106	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
107	mtx_unlock(&taskqueue_queues_mutex);
108
109	mtx_destroy(&queue->tq_mutex);
110	free(queue, M_TASKQUEUE);
111}
112
113/*
114 * Returns with the taskqueue locked.
115 */
116struct taskqueue *
117taskqueue_find(const char *name)
118{
119	struct taskqueue *queue;
120
121	mtx_lock(&taskqueue_queues_mutex);
122	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
123		mtx_lock(&queue->tq_mutex);
124		if (!strcmp(queue->tq_name, name)) {
125			mtx_unlock(&taskqueue_queues_mutex);
126			return queue;
127		}
128		mtx_unlock(&queue->tq_mutex);
129	}
130	mtx_unlock(&taskqueue_queues_mutex);
131	return 0;
132}
133
134int
135taskqueue_enqueue(struct taskqueue *queue, struct task *task)
136{
137	struct task *ins;
138	struct task *prev;
139
140	mtx_lock(&queue->tq_mutex);
141
142	/*
143	 * Don't allow new tasks on a queue which is being freed.
144	 */
145	if (queue->tq_draining) {
146		mtx_unlock(&queue->tq_mutex);
147		return EPIPE;
148	}
149
150	/*
151	 * Count multiple enqueues.
152	 */
153	if (task->ta_pending) {
154		task->ta_pending++;
155		mtx_unlock(&queue->tq_mutex);
156		return 0;
157	}
158
159	/*
160	 * Optimise the case when all tasks have the same priority.
161	 */
162	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
163	if (!prev || prev->ta_priority >= task->ta_priority) {
164		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
165	} else {
166		prev = 0;
167		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
168		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
169			if (ins->ta_priority < task->ta_priority)
170				break;
171
172		if (prev)
173			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
174		else
175			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
176	}
177
178	task->ta_pending = 1;
179	if (queue->tq_enqueue)
180		queue->tq_enqueue(queue->tq_context);
181
182	mtx_unlock(&queue->tq_mutex);
183
184	return 0;
185}
186
187void
188taskqueue_run(struct taskqueue *queue)
189{
190	struct task *task;
191	int pending;
192
193	mtx_lock(&queue->tq_mutex);
194	while (STAILQ_FIRST(&queue->tq_queue)) {
195		/*
196		 * Carefully remove the first task from the queue and
197		 * zero its pending count.
198		 */
199		task = STAILQ_FIRST(&queue->tq_queue);
200		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
201		pending = task->ta_pending;
202		task->ta_pending = 0;
203		mtx_unlock(&queue->tq_mutex);
204
205		task->ta_func(task->ta_context, pending);
206
207		mtx_lock(&queue->tq_mutex);
208	}
209	mtx_unlock(&queue->tq_mutex);
210}
211
212static void
213taskqueue_swi_enqueue(void *context)
214{
215	swi_sched(taskqueue_ih, 0);
216}
217
218static void
219taskqueue_swi_run(void *dummy)
220{
221	taskqueue_run(taskqueue_swi);
222}
223
224static void
225taskqueue_swi_giant_enqueue(void *context)
226{
227	swi_sched(taskqueue_giant_ih, 0);
228}
229
230static void
231taskqueue_swi_giant_run(void *dummy)
232{
233	taskqueue_run(taskqueue_swi_giant);
234}
235
236TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
237		 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
238		     INTR_MPSAFE, &taskqueue_ih));
239
240TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, 0,
241		 swi_add(NULL, "Giant task queue", taskqueue_swi_giant_run,
242		     NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
243