subr_taskqueue.c revision 66698 
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 66698 2000-10-05 23:09:57Z 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
39MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
40
41static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
42
43struct taskqueue {
44	STAILQ_ENTRY(taskqueue)	tq_link;
45	STAILQ_HEAD(, task)	tq_queue;
46	const char		*tq_name;
47	taskqueue_enqueue_fn	tq_enqueue;
48	void			*tq_context;
49	int			tq_draining;
50};
51
52struct taskqueue *
53taskqueue_create(const char *name, int mflags,
54		 taskqueue_enqueue_fn enqueue, void *context)
55{
56	struct taskqueue *queue;
57	static int once = 1;
58	int s;
59
60	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags);
61	if (!queue)
62		return 0;
63	STAILQ_INIT(&queue->tq_queue);
64	queue->tq_name = name;
65	queue->tq_enqueue = enqueue;
66	queue->tq_context = context;
67	queue->tq_draining = 0;
68
69	s = splhigh();
70	if (once) {
71		STAILQ_INIT(&taskqueue_queues);
72		once = 0;
73	}
74	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
75	splx(s);
76
77	return queue;
78}
79
80void
81taskqueue_free(struct taskqueue *queue)
82{
83	int s = splhigh();
84	queue->tq_draining = 1;
85	splx(s);
86
87	taskqueue_run(queue);
88
89	s = splhigh();
90	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
91	splx(s);
92
93	free(queue, M_TASKQUEUE);
94}
95
96struct taskqueue *
97taskqueue_find(const char *name)
98{
99	struct taskqueue *queue;
100	int s;
101
102	s = splhigh();
103	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link)
104		if (!strcmp(queue->tq_name, name)) {
105			splx(s);
106			return queue;
107		}
108	splx(s);
109	return 0;
110}
111
112int
113taskqueue_enqueue(struct taskqueue *queue, struct task *task)
114{
115	struct task *ins;
116	struct task *prev;
117
118	int s = splhigh();
119
120	/*
121	 * Don't allow new tasks on a queue which is being freed.
122	 */
123	if (queue->tq_draining) {
124		splx(s);
125		return EPIPE;
126	}
127
128	/*
129	 * Count multiple enqueues.
130	 */
131	if (task->ta_pending) {
132		task->ta_pending++;
133		splx(s);
134		return 0;
135	}
136
137	/*
138	 * Optimise the case when all tasks have the same priority.
139	 */
140	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
141	if (!prev || prev->ta_priority >= task->ta_priority) {
142		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
143	} else {
144		prev = 0;
145		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
146		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
147			if (ins->ta_priority < task->ta_priority)
148				break;
149
150		if (prev)
151			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
152		else
153			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
154	}
155
156	task->ta_pending = 1;
157	if (queue->tq_enqueue)
158		queue->tq_enqueue(queue->tq_context);
159
160	splx(s);
161
162	return 0;
163}
164
165void
166taskqueue_run(struct taskqueue *queue)
167{
168	int s;
169	struct task *task;
170	int pending;
171
172	s = splhigh();
173	while (STAILQ_FIRST(&queue->tq_queue)) {
174		/*
175		 * Carefully remove the first task from the queue and
176		 * zero its pending count.
177		 */
178		task = STAILQ_FIRST(&queue->tq_queue);
179		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
180		pending = task->ta_pending;
181		task->ta_pending = 0;
182		splx(s);
183
184		task->ta_func(task->ta_context, pending);
185
186		s = splhigh();
187	}
188	splx(s);
189}
190
191static void
192taskqueue_swi_enqueue(void *context)
193{
194	setsofttq();
195}
196
197static void
198taskqueue_swi_run(void)
199{
200	taskqueue_run(taskqueue_swi);
201}
202
203TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
204		 register_swi(SWI_TQ, taskqueue_swi_run));
205