subr_taskqueue.c revision 93818 
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: head/sys/kern/subr_taskqueue.c 93818 2002-04-04 21:03:38Z jhb $
27 */
28
29#include <sys/param.h>
30#include <sys/systm.h>
31#include <sys/bus.h>
32#include <sys/interrupt.h>
33#include <sys/kernel.h>
34#include <sys/lock.h>
35#include <sys/malloc.h>
36#include <sys/mutex.h>
37#include <sys/taskqueue.h>
38
39static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
40
41static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
42
43static void	*taskqueue_ih;
44static struct mtx taskqueue_queues_mutex;
45
46struct taskqueue {
47	STAILQ_ENTRY(taskqueue)	tq_link;
48	STAILQ_HEAD(, task)	tq_queue;
49	const char		*tq_name;
50	taskqueue_enqueue_fn	tq_enqueue;
51	void			*tq_context;
52	int			tq_draining;
53	struct mtx		tq_mutex;
54};
55
56static void	init_taskqueue_list(void *data);
57
58static void
59init_taskqueue_list(void *data __unused)
60{
61
62	mtx_init(&taskqueue_queues_mutex, "taskqueue list", NULL, MTX_DEF);
63	STAILQ_INIT(&taskqueue_queues);
64}
65SYSINIT(taskqueue_list, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_taskqueue_list,
66    NULL);
67
68struct taskqueue *
69taskqueue_create(const char *name, int mflags,
70		 taskqueue_enqueue_fn enqueue, void *context)
71{
72	struct taskqueue *queue;
73
74	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
75	if (!queue)
76		return 0;
77
78	STAILQ_INIT(&queue->tq_queue);
79	queue->tq_name = name;
80	queue->tq_enqueue = enqueue;
81	queue->tq_context = context;
82	queue->tq_draining = 0;
83	mtx_init(&queue->tq_mutex, "taskqueue", NULL, MTX_DEF);
84
85	mtx_lock(&taskqueue_queues_mutex);
86	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
87	mtx_unlock(&taskqueue_queues_mutex);
88
89	return queue;
90}
91
92void
93taskqueue_free(struct taskqueue *queue)
94{
95
96	mtx_lock(&queue->tq_mutex);
97	queue->tq_draining = 1;
98	mtx_unlock(&queue->tq_mutex);
99
100	taskqueue_run(queue);
101
102	mtx_lock(&taskqueue_queues_mutex);
103	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
104	mtx_unlock(&taskqueue_queues_mutex);
105
106	mtx_destroy(&queue->tq_mutex);
107	free(queue, M_TASKQUEUE);
108}
109
110/*
111 * Returns with the taskqueue locked.
112 */
113struct taskqueue *
114taskqueue_find(const char *name)
115{
116	struct taskqueue *queue;
117
118	mtx_lock(&taskqueue_queues_mutex);
119	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
120		mtx_lock(&queue->tq_mutex);
121		if (!strcmp(queue->tq_name, name)) {
122			mtx_unlock(&taskqueue_queues_mutex);
123			return queue;
124		}
125		mtx_unlock(&queue->tq_mutex);
126	}
127	mtx_unlock(&taskqueue_queues_mutex);
128	return 0;
129}
130
131int
132taskqueue_enqueue(struct taskqueue *queue, struct task *task)
133{
134	struct task *ins;
135	struct task *prev;
136
137	mtx_lock(&queue->tq_mutex);
138
139	/*
140	 * Don't allow new tasks on a queue which is being freed.
141	 */
142	if (queue->tq_draining) {
143		mtx_unlock(&queue->tq_mutex);
144		return EPIPE;
145	}
146
147	/*
148	 * Count multiple enqueues.
149	 */
150	if (task->ta_pending) {
151		task->ta_pending++;
152		mtx_unlock(&queue->tq_mutex);
153		return 0;
154	}
155
156	/*
157	 * Optimise the case when all tasks have the same priority.
158	 */
159	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
160	if (!prev || prev->ta_priority >= task->ta_priority) {
161		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
162	} else {
163		prev = 0;
164		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
165		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
166			if (ins->ta_priority < task->ta_priority)
167				break;
168
169		if (prev)
170			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
171		else
172			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
173	}
174
175	task->ta_pending = 1;
176	if (queue->tq_enqueue)
177		queue->tq_enqueue(queue->tq_context);
178
179	mtx_unlock(&queue->tq_mutex);
180
181	return 0;
182}
183
184void
185taskqueue_run(struct taskqueue *queue)
186{
187	struct task *task;
188	int pending;
189
190	mtx_lock(&queue->tq_mutex);
191	while (STAILQ_FIRST(&queue->tq_queue)) {
192		/*
193		 * Carefully remove the first task from the queue and
194		 * zero its pending count.
195		 */
196		task = STAILQ_FIRST(&queue->tq_queue);
197		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
198		pending = task->ta_pending;
199		task->ta_pending = 0;
200		mtx_unlock(&queue->tq_mutex);
201
202		task->ta_func(task->ta_context, pending);
203
204		mtx_lock(&queue->tq_mutex);
205	}
206	mtx_unlock(&queue->tq_mutex);
207}
208
209static void
210taskqueue_swi_enqueue(void *context)
211{
212	swi_sched(taskqueue_ih, 0);
213}
214
215static void
216taskqueue_swi_run(void *dummy)
217{
218	taskqueue_run(taskqueue_swi);
219}
220
221TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
222		 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ, 0,
223		     &taskqueue_ih));
224