subr_taskqueue.c revision 72238 
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 72238 2001-02-09 17:46:35Z jhb $
27 */
28
29#include <sys/param.h>
30#include <sys/bus.h>
31#include <sys/queue.h>
32#include <sys/systm.h>
33#include <sys/kernel.h>
34#include <sys/taskqueue.h>
35#include <sys/interrupt.h>
36#include <sys/ipl.h>
37#include <sys/malloc.h>
38
39static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
40
41static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
42
43static void	*taskqueue_ih;
44
45struct taskqueue {
46	STAILQ_ENTRY(taskqueue)	tq_link;
47	STAILQ_HEAD(, task)	tq_queue;
48	const char		*tq_name;
49	taskqueue_enqueue_fn	tq_enqueue;
50	void			*tq_context;
51	int			tq_draining;
52};
53
54struct taskqueue *
55taskqueue_create(const char *name, int mflags,
56		 taskqueue_enqueue_fn enqueue, void *context)
57{
58	struct taskqueue *queue;
59	static int once = 1;
60	int s;
61
62	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags);
63	if (!queue)
64		return 0;
65	STAILQ_INIT(&queue->tq_queue);
66	queue->tq_name = name;
67	queue->tq_enqueue = enqueue;
68	queue->tq_context = context;
69	queue->tq_draining = 0;
70
71	s = splhigh();
72	if (once) {
73		STAILQ_INIT(&taskqueue_queues);
74		once = 0;
75	}
76	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
77	splx(s);
78
79	return queue;
80}
81
82void
83taskqueue_free(struct taskqueue *queue)
84{
85	int s = splhigh();
86	queue->tq_draining = 1;
87	splx(s);
88
89	taskqueue_run(queue);
90
91	s = splhigh();
92	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
93	splx(s);
94
95	free(queue, M_TASKQUEUE);
96}
97
98struct taskqueue *
99taskqueue_find(const char *name)
100{
101	struct taskqueue *queue;
102	int s;
103
104	s = splhigh();
105	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link)
106		if (!strcmp(queue->tq_name, name)) {
107			splx(s);
108			return queue;
109		}
110	splx(s);
111	return 0;
112}
113
114int
115taskqueue_enqueue(struct taskqueue *queue, struct task *task)
116{
117	struct task *ins;
118	struct task *prev;
119
120	int s = splhigh();
121
122	/*
123	 * Don't allow new tasks on a queue which is being freed.
124	 */
125	if (queue->tq_draining) {
126		splx(s);
127		return EPIPE;
128	}
129
130	/*
131	 * Count multiple enqueues.
132	 */
133	if (task->ta_pending) {
134		task->ta_pending++;
135		splx(s);
136		return 0;
137	}
138
139	/*
140	 * Optimise the case when all tasks have the same priority.
141	 */
142	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
143	if (!prev || prev->ta_priority >= task->ta_priority) {
144		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
145	} else {
146		prev = 0;
147		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
148		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
149			if (ins->ta_priority < task->ta_priority)
150				break;
151
152		if (prev)
153			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
154		else
155			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
156	}
157
158	task->ta_pending = 1;
159	if (queue->tq_enqueue)
160		queue->tq_enqueue(queue->tq_context);
161
162	splx(s);
163
164	return 0;
165}
166
167void
168taskqueue_run(struct taskqueue *queue)
169{
170	int s;
171	struct task *task;
172	int pending;
173
174	s = splhigh();
175	while (STAILQ_FIRST(&queue->tq_queue)) {
176		/*
177		 * Carefully remove the first task from the queue and
178		 * zero its pending count.
179		 */
180		task = STAILQ_FIRST(&queue->tq_queue);
181		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
182		pending = task->ta_pending;
183		task->ta_pending = 0;
184		splx(s);
185
186		task->ta_func(task->ta_context, pending);
187
188		s = splhigh();
189	}
190	splx(s);
191}
192
193static void
194taskqueue_swi_enqueue(void *context)
195{
196	swi_sched(taskqueue_ih, SWI_NOSWITCH);
197}
198
199static void
200taskqueue_swi_run(void *dummy)
201{
202	taskqueue_run(taskqueue_swi);
203}
204
205TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
206		 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ, 0,
207		     &taskqueue_ih));
208