subr_taskqueue.c revision 101154 
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 101153 2002-08-01 13:35:38Z 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	KASSERT(queue->tq_draining == 0, ("free'ing a draining taskqueue"));
98	queue->tq_draining = 1;
99	mtx_unlock(&queue->tq_mutex);
100
101	taskqueue_run(queue);
102
103	mtx_lock(&taskqueue_queues_mutex);
104	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
105	mtx_unlock(&taskqueue_queues_mutex);
106
107	mtx_destroy(&queue->tq_mutex);
108	free(queue, M_TASKQUEUE);
109}
110
111/*
112 * Returns with the taskqueue locked.
113 */
114struct taskqueue *
115taskqueue_find(const char *name)
116{
117	struct taskqueue *queue;
118
119	mtx_lock(&taskqueue_queues_mutex);
120	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
121		mtx_lock(&queue->tq_mutex);
122		if (!strcmp(queue->tq_name, name)) {
123			mtx_unlock(&taskqueue_queues_mutex);
124			return queue;
125		}
126		mtx_unlock(&queue->tq_mutex);
127	}
128	mtx_unlock(&taskqueue_queues_mutex);
129	return 0;
130}
131
132int
133taskqueue_enqueue(struct taskqueue *queue, struct task *task)
134{
135	struct task *ins;
136	struct task *prev;
137
138	mtx_lock(&queue->tq_mutex);
139
140	/*
141	 * Don't allow new tasks on a queue which is being freed.
142	 */
143	if (queue->tq_draining) {
144		mtx_unlock(&queue->tq_mutex);
145		return EPIPE;
146	}
147
148	/*
149	 * Count multiple enqueues.
150	 */
151	if (task->ta_pending) {
152		task->ta_pending++;
153		mtx_unlock(&queue->tq_mutex);
154		return 0;
155	}
156
157	/*
158	 * Optimise the case when all tasks have the same priority.
159	 */
160	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
161	if (!prev || prev->ta_priority >= task->ta_priority) {
162		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
163	} else {
164		prev = 0;
165		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
166		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
167			if (ins->ta_priority < task->ta_priority)
168				break;
169
170		if (prev)
171			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
172		else
173			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
174	}
175
176	task->ta_pending = 1;
177	if (queue->tq_enqueue)
178		queue->tq_enqueue(queue->tq_context);
179
180	mtx_unlock(&queue->tq_mutex);
181
182	return 0;
183}
184
185void
186taskqueue_run(struct taskqueue *queue)
187{
188	struct task *task;
189	int pending;
190
191	mtx_lock(&queue->tq_mutex);
192	while (STAILQ_FIRST(&queue->tq_queue)) {
193		/*
194		 * Carefully remove the first task from the queue and
195		 * zero its pending count.
196		 */
197		task = STAILQ_FIRST(&queue->tq_queue);
198		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
199		pending = task->ta_pending;
200		task->ta_pending = 0;
201		mtx_unlock(&queue->tq_mutex);
202
203		task->ta_func(task->ta_context, pending);
204
205		mtx_lock(&queue->tq_mutex);
206	}
207	mtx_unlock(&queue->tq_mutex);
208}
209
210static void
211taskqueue_swi_enqueue(void *context)
212{
213	swi_sched(taskqueue_ih, 0);
214}
215
216static void
217taskqueue_swi_run(void *dummy)
218{
219	taskqueue_run(taskqueue_swi);
220}
221
222TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
223		 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ, 0,
224		     &taskqueue_ih));
225