subr_taskqueue.c revision 76666 
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 76666 2001-05-16 02:52:06Z alfred $
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/malloc.h>
37
38static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
39
40static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
41
42static void	*taskqueue_ih;
43
44struct taskqueue {
45	STAILQ_ENTRY(taskqueue)	tq_link;
46	STAILQ_HEAD(, task)	tq_queue;
47	const char		*tq_name;
48	taskqueue_enqueue_fn	tq_enqueue;
49	void			*tq_context;
50	int			tq_draining;
51};
52
53struct taskqueue *
54taskqueue_create(const char *name, int mflags,
55		 taskqueue_enqueue_fn enqueue, void *context)
56{
57	struct taskqueue *queue;
58	static int once = 1;
59	int s;
60
61	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags);
62	if (!queue)
63		return 0;
64	STAILQ_INIT(&queue->tq_queue);
65	queue->tq_name = name;
66	queue->tq_enqueue = enqueue;
67	queue->tq_context = context;
68	queue->tq_draining = 0;
69
70	s = splhigh();
71	if (once) {
72		STAILQ_INIT(&taskqueue_queues);
73		once = 0;
74	}
75	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
76	splx(s);
77
78	return queue;
79}
80
81void
82taskqueue_free(struct taskqueue *queue)
83{
84	int s = splhigh();
85	queue->tq_draining = 1;
86	splx(s);
87
88	taskqueue_run(queue);
89
90	s = splhigh();
91	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
92	splx(s);
93
94	free(queue, M_TASKQUEUE);
95}
96
97struct taskqueue *
98taskqueue_find(const char *name)
99{
100	struct taskqueue *queue;
101	int s;
102
103	s = splhigh();
104	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link)
105		if (!strcmp(queue->tq_name, name)) {
106			splx(s);
107			return queue;
108		}
109	splx(s);
110	return 0;
111}
112
113int
114taskqueue_enqueue(struct taskqueue *queue, struct task *task)
115{
116	struct task *ins;
117	struct task *prev;
118
119	int s = splhigh();
120
121	/*
122	 * Don't allow new tasks on a queue which is being freed.
123	 */
124	if (queue->tq_draining) {
125		splx(s);
126		return EPIPE;
127	}
128
129	/*
130	 * Count multiple enqueues.
131	 */
132	if (task->ta_pending) {
133		task->ta_pending++;
134		splx(s);
135		return 0;
136	}
137
138	/*
139	 * Optimise the case when all tasks have the same priority.
140	 */
141	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
142	if (!prev || prev->ta_priority >= task->ta_priority) {
143		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
144	} else {
145		prev = 0;
146		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
147		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
148			if (ins->ta_priority < task->ta_priority)
149				break;
150
151		if (prev)
152			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
153		else
154			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
155	}
156
157	task->ta_pending = 1;
158	if (queue->tq_enqueue)
159		queue->tq_enqueue(queue->tq_context);
160
161	splx(s);
162
163	return 0;
164}
165
166void
167taskqueue_run(struct taskqueue *queue)
168{
169	int s;
170	struct task *task;
171	int pending;
172
173	s = splhigh();
174	while (STAILQ_FIRST(&queue->tq_queue)) {
175		/*
176		 * Carefully remove the first task from the queue and
177		 * zero its pending count.
178		 */
179		task = STAILQ_FIRST(&queue->tq_queue);
180		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
181		pending = task->ta_pending;
182		task->ta_pending = 0;
183		splx(s);
184
185		task->ta_func(task->ta_context, pending);
186
187		s = splhigh();
188	}
189	splx(s);
190}
191
192static void
193taskqueue_swi_enqueue(void *context)
194{
195	swi_sched(taskqueue_ih, SWI_NOSWITCH);
196}
197
198static void
199taskqueue_swi_run(void *dummy)
200{
201	taskqueue_run(taskqueue_swi);
202}
203
204TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
205		 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ, 0,
206		     &taskqueue_ih));
207