subr_taskqueue.c revision 85521 
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 85521 2001-10-26 06:32:21Z jhb $
27 */
28
29#include <sys/param.h>
30#include <sys/systm.h>
31#include <sys/bus.h>
32#include <sys/kernel.h>
33#include <sys/lock.h>
34#include <sys/interrupt.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", MTX_DEF);
63	STAILQ_INIT(&taskqueue_queues);
64}
65SYSINIT(taskqueue_list, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_taskqueue_list,
66    NULL);
67
68void
69task_init(struct task *task, int priority, task_fn_t *func, void *context)
70{
71
72	KASSERT(task != NULL, ("task == NULL"));
73
74	mtx_init(&task->ta_mutex, "task", MTX_DEF);
75	mtx_lock(&task->ta_mutex);
76	task->ta_pending = 0;
77	task->ta_priority = priority;
78	task->ta_func = func;
79	task->ta_context = context;
80	mtx_unlock(&task->ta_mutex);
81}
82
83void
84task_destroy(struct task *task)
85{
86
87	mtx_destroy(&task->ta_mutex);
88}
89
90struct taskqueue *
91taskqueue_create(const char *name, int mflags,
92		 taskqueue_enqueue_fn enqueue, void *context)
93{
94	struct taskqueue *queue;
95
96	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
97	if (!queue)
98		return 0;
99
100	STAILQ_INIT(&queue->tq_queue);
101	queue->tq_name = name;
102	queue->tq_enqueue = enqueue;
103	queue->tq_context = context;
104	queue->tq_draining = 0;
105	mtx_init(&queue->tq_mutex, "taskqueue", MTX_DEF);
106
107	mtx_lock(&taskqueue_queues_mutex);
108	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
109	mtx_unlock(&taskqueue_queues_mutex);
110
111	return queue;
112}
113
114void
115taskqueue_free(struct taskqueue *queue)
116{
117
118	mtx_lock(&queue->tq_mutex);
119	queue->tq_draining = 1;
120	mtx_unlock(&queue->tq_mutex);
121
122	taskqueue_run(queue);
123
124	mtx_lock(&taskqueue_queues_mutex);
125	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
126	mtx_unlock(&taskqueue_queues_mutex);
127
128	mtx_destroy(&queue->tq_mutex);
129	free(queue, M_TASKQUEUE);
130}
131
132/*
133 * Returns with the taskqueue locked.
134 */
135struct taskqueue *
136taskqueue_find(const char *name)
137{
138	struct taskqueue *queue;
139
140	mtx_lock(&taskqueue_queues_mutex);
141	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link) {
142		mtx_lock(&queue->tq_mutex);
143		if (!strcmp(queue->tq_name, name)) {
144			mtx_unlock(&taskqueue_queues_mutex);
145			return queue;
146		}
147		mtx_unlock(&queue->tq_mutex);
148	}
149	mtx_unlock(&taskqueue_queues_mutex);
150	return 0;
151}
152
153int
154taskqueue_enqueue(struct taskqueue *queue, struct task *task)
155{
156	struct task *ins;
157	struct task *prev;
158
159	/*
160	 * Don't allow new tasks on a queue which is being freed.
161	 */
162	mtx_lock(&queue->tq_mutex);
163	if (queue->tq_draining) {
164		mtx_unlock(&queue->tq_mutex);
165		return EPIPE;
166	}
167
168	/*
169	 * Count multiple enqueues.
170	 */
171	mtx_lock(&task->ta_mutex);
172	if (task->ta_pending) {
173		task->ta_pending++;
174		mtx_unlock(&task->ta_mutex);
175		mtx_unlock(&queue->tq_mutex);
176		return 0;
177	}
178
179	/*
180	 * Optimise the case when all tasks have the same priority.
181	 */
182	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
183	if (!prev || prev->ta_priority >= task->ta_priority) {
184		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
185	} else {
186		prev = 0;
187		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
188		     prev = ins, ins = STAILQ_NEXT(ins, ta_link))
189			if (ins->ta_priority < task->ta_priority)
190				break;
191
192		if (prev)
193			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
194		else
195			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
196	}
197
198	task->ta_pending = 1;
199	mtx_unlock(&task->ta_mutex);
200
201	if (queue->tq_enqueue)
202		queue->tq_enqueue(queue->tq_context);
203	mtx_unlock(&queue->tq_mutex);
204	return 0;
205}
206
207void
208taskqueue_run(struct taskqueue *queue)
209{
210	struct task *task;
211	task_fn_t *saved_func;
212	void *arg;
213	int pending;
214
215	mtx_lock(&queue->tq_mutex);
216	while (STAILQ_FIRST(&queue->tq_queue)) {
217		/*
218		 * Carefully remove the first task from the queue and
219		 * zero its pending count.
220		 */
221		task = STAILQ_FIRST(&queue->tq_queue);
222		mtx_lock(&task->ta_mutex);
223		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
224		mtx_unlock(&queue->tq_mutex);
225		pending = task->ta_pending;
226		task->ta_pending = 0;
227		saved_func = task->ta_func;
228		arg = task->ta_context;
229		mtx_unlock(&task->ta_mutex);
230
231		saved_func(arg, pending);
232
233		mtx_lock(&queue->tq_mutex);
234	}
235	mtx_unlock(&queue->tq_mutex);
236}
237
238static void
239taskqueue_swi_enqueue(void *context)
240{
241	swi_sched(taskqueue_ih, SWI_NOSWITCH);
242}
243
244static void
245taskqueue_swi_run(void *dummy)
246{
247	taskqueue_run(taskqueue_swi);
248}
249
250TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
251		 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ, 0,
252		     &taskqueue_ih));
253