subr_taskqueue.c revision 111528 
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 111528 2003-02-26 03:15:42Z scottl $
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 void	*taskqueue_giant_ih;
45static struct mtx taskqueue_queues_mutex;
46
47struct taskqueue {
48	STAILQ_ENTRY(taskqueue)	tq_link;
49	STAILQ_HEAD(, task)	tq_queue;
50	const char		*tq_name;
51	taskqueue_enqueue_fn	tq_enqueue;
52	void			*tq_context;
53	int			tq_draining;
54	struct mtx		tq_mutex;
55};
56
57static void	init_taskqueue_list(void *data);
58
59static void
60init_taskqueue_list(void *data __unused)
61{
62
63	mtx_init(&taskqueue_queues_mutex, "taskqueue list", NULL, MTX_DEF);
64	STAILQ_INIT(&taskqueue_queues);
65}
66SYSINIT(taskqueue_list, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_taskqueue_list,
67    NULL);
68
69struct taskqueue *
70taskqueue_create(const char *name, int mflags,
71		 taskqueue_enqueue_fn enqueue, void *context)
72{
73	struct taskqueue *queue;
74
75	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
76	if (!queue)
77		return 0;
78
79	STAILQ_INIT(&queue->tq_queue);
80	queue->tq_name = name;
81	queue->tq_enqueue = enqueue;
82	queue->tq_context = context;
83	queue->tq_draining = 0;
84	mtx_init(&queue->tq_mutex, "taskqueue", NULL, MTX_DEF);
85
86	mtx_lock(&taskqueue_queues_mutex);
87	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
88	mtx_unlock(&taskqueue_queues_mutex);
89
90	return queue;
91}
92
93void
94taskqueue_free(struct taskqueue *queue)
95{
96
97	mtx_lock(&queue->tq_mutex);
98	KASSERT(queue->tq_draining == 0, ("free'ing a draining taskqueue"));
99	queue->tq_draining = 1;
100	mtx_unlock(&queue->tq_mutex);
101
102	taskqueue_run(queue);
103
104	mtx_lock(&taskqueue_queues_mutex);
105	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
106	mtx_unlock(&taskqueue_queues_mutex);
107
108	mtx_destroy(&queue->tq_mutex);
109	free(queue, M_TASKQUEUE);
110}
111
112/*
113 * Returns with the taskqueue locked.
114 */
115struct taskqueue *
116taskqueue_find(const char *name)
117{
118	struct taskqueue *queue;
119
120	mtx_lock(&taskqueue_queues_mutex);
121	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
122		mtx_lock(&queue->tq_mutex);
123		if (!strcmp(queue->tq_name, name)) {
124			mtx_unlock(&taskqueue_queues_mutex);
125			return queue;
126		}
127		mtx_unlock(&queue->tq_mutex);
128	}
129	mtx_unlock(&taskqueue_queues_mutex);
130	return 0;
131}
132
133int
134taskqueue_enqueue(struct taskqueue *queue, struct task *task)
135{
136	struct task *ins;
137	struct task *prev;
138
139	mtx_lock(&queue->tq_mutex);
140
141	/*
142	 * Don't allow new tasks on a queue which is being freed.
143	 */
144	if (queue->tq_draining) {
145		mtx_unlock(&queue->tq_mutex);
146		return EPIPE;
147	}
148
149	/*
150	 * Count multiple enqueues.
151	 */
152	if (task->ta_pending) {
153		task->ta_pending++;
154		mtx_unlock(&queue->tq_mutex);
155		return 0;
156	}
157
158	/*
159	 * Optimise the case when all tasks have the same priority.
160	 */
161	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
162	if (!prev || prev->ta_priority >= task->ta_priority) {
163		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
164	} else {
165		prev = 0;
166		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
167		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
168			if (ins->ta_priority < task->ta_priority)
169				break;
170
171		if (prev)
172			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
173		else
174			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
175	}
176
177	task->ta_pending = 1;
178	if (queue->tq_enqueue)
179		queue->tq_enqueue(queue->tq_context);
180
181	mtx_unlock(&queue->tq_mutex);
182
183	return 0;
184}
185
186void
187taskqueue_run(struct taskqueue *queue)
188{
189	struct task *task;
190	int pending;
191
192	mtx_lock(&queue->tq_mutex);
193	while (STAILQ_FIRST(&queue->tq_queue)) {
194		/*
195		 * Carefully remove the first task from the queue and
196		 * zero its pending count.
197		 */
198		task = STAILQ_FIRST(&queue->tq_queue);
199		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
200		pending = task->ta_pending;
201		task->ta_pending = 0;
202		mtx_unlock(&queue->tq_mutex);
203
204		task->ta_func(task->ta_context, pending);
205
206		mtx_lock(&queue->tq_mutex);
207	}
208	mtx_unlock(&queue->tq_mutex);
209}
210
211static void
212taskqueue_swi_enqueue(void *context)
213{
214	swi_sched(taskqueue_ih, 0);
215}
216
217static void
218taskqueue_swi_run(void *dummy)
219{
220	taskqueue_run(taskqueue_swi);
221}
222
223static void
224taskqueue_swi_giant_enqueue(void *context)
225{
226	swi_sched(taskqueue_giant_ih, 0);
227}
228
229static void
230taskqueue_swi_giant_run(void *dummy)
231{
232	taskqueue_run(taskqueue_swi_giant);
233}
234
235TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
236		 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
237		     INTR_MPSAFE, &taskqueue_ih));
238
239TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, 0,
240		 swi_add(NULL, "Giant task queue", taskqueue_swi_giant_run,
241		     NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
242