subr_taskqueue.c revision 64199 
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 64199 2000-08-03 16:37:46Z hsu $
27 */
28
29#include <sys/param.h>
30#include <sys/queue.h>
31#include <sys/systm.h>
32#include <sys/kernel.h>
33#include <sys/taskqueue.h>
34#include <sys/interrupt.h>
35#include <sys/malloc.h>
36#include <machine/ipl.h>
37
38MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
39
40static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
41
42struct taskqueue {
43	STAILQ_ENTRY(taskqueue)	tq_link;
44	STAILQ_HEAD(, task)	tq_queue;
45	const char		*tq_name;
46	taskqueue_enqueue_fn	tq_enqueue;
47	void			*tq_context;
48	int			tq_draining;
49};
50
51struct taskqueue *
52taskqueue_create(const char *name, int mflags,
53		 taskqueue_enqueue_fn enqueue, void *context)
54{
55	struct taskqueue *queue;
56	static int once = 1;
57	int s;
58
59	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags);
60	if (!queue)
61		return 0;
62	STAILQ_INIT(&queue->tq_queue);
63	queue->tq_name = name;
64	queue->tq_enqueue = enqueue;
65	queue->tq_context = context;
66	queue->tq_draining = 0;
67
68	s = splhigh();
69	if (once) {
70		STAILQ_INIT(&taskqueue_queues);
71		once = 0;
72	}
73	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
74	splx(s);
75
76	return queue;
77}
78
79void
80taskqueue_free(struct taskqueue *queue)
81{
82	int s = splhigh();
83	queue->tq_draining = 1;
84	splx(s);
85
86	taskqueue_run(queue);
87
88	s = splhigh();
89	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
90	splx(s);
91
92	free(queue, M_TASKQUEUE);
93}
94
95struct taskqueue *
96taskqueue_find(const char *name)
97{
98	struct taskqueue *queue;
99	int s;
100
101	s = splhigh();
102	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link)
103		if (!strcmp(queue->tq_name, name)) {
104			splx(s);
105			return queue;
106		}
107	splx(s);
108	return 0;
109}
110
111int
112taskqueue_enqueue(struct taskqueue *queue, struct task *task)
113{
114	struct task *ins;
115	struct task *prev;
116
117	int s = splhigh();
118
119	/*
120	 * Don't allow new tasks on a queue which is being freed.
121	 */
122	if (queue->tq_draining) {
123		splx(s);
124		return EPIPE;
125	}
126
127	/*
128	 * Count multiple enqueues.
129	 */
130	if (task->ta_pending) {
131		task->ta_pending++;
132		splx(s);
133		return 0;
134	}
135
136	/*
137	 * Optimise the case when all tasks have the same priority.
138	 */
139	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
140	if (!prev || prev->ta_priority >= task->ta_priority) {
141		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
142	} else {
143		prev = 0;
144		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
145		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
146			if (ins->ta_priority < task->ta_priority)
147				break;
148
149		if (prev)
150			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
151		else
152			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
153	}
154
155	task->ta_pending = 1;
156	if (queue->tq_enqueue)
157		queue->tq_enqueue(queue->tq_context);
158
159	splx(s);
160
161	return 0;
162}
163
164void
165taskqueue_run(struct taskqueue *queue)
166{
167	int s;
168	struct task *task;
169	int pending;
170
171	s = splhigh();
172	while (STAILQ_FIRST(&queue->tq_queue)) {
173		/*
174		 * Carefully remove the first task from the queue and
175		 * zero its pending count.
176		 */
177		task = STAILQ_FIRST(&queue->tq_queue);
178		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
179		pending = task->ta_pending;
180		task->ta_pending = 0;
181		splx(s);
182
183		task->ta_func(task->ta_context, pending);
184
185		s = splhigh();
186	}
187	splx(s);
188}
189
190static void
191taskqueue_swi_enqueue(void *context)
192{
193	setsofttq();
194}
195
196static void
197taskqueue_swi_run(void)
198{
199	taskqueue_run(taskqueue_swi);
200}
201
202TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
203		 register_swi(SWI_TQ, taskqueue_swi_run));
204