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: releng/5.0/sys/kern/subr_taskqueue.c 101154 2002-08-01 13:37:22Z 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
39 static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
40
41 static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
42
43 static void *taskqueue_ih;
44 static struct mtx taskqueue_queues_mutex;
45
46 struct 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
56 static void init_taskqueue_list(void *data);
57
58 static void
59 init_taskqueue_list(void *data __unused)
60 {
61
62 mtx_init(&taskqueue_queues_mutex, "taskqueue list", NULL, MTX_DEF);
63 STAILQ_INIT(&taskqueue_queues);
64 }
65 SYSINIT(taskqueue_list, SI_SUB_INTRINSIC, SI_ORDER_ANY, init_taskqueue_list,
66 NULL);
67
68 struct taskqueue *
69 taskqueue_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
92 void
93 taskqueue_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 */
114 struct taskqueue *
115 taskqueue_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
132 int
133 taskqueue_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
185 void
186 taskqueue_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
210 static void
211 taskqueue_swi_enqueue(void *context)
212 {
213 swi_sched(taskqueue_ih, 0);
214 }
215
216 static void
217 taskqueue_swi_run(void *dummy)
218 {
219 taskqueue_run(taskqueue_swi);
220 }
221
222 TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
223 swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ, 0,
224 &taskqueue_ih));
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