1/* $NetBSD: sysmon_taskq.c,v 1.19 2015/04/28 11:58:49 martin Exp $ */
2
3/*
4 * Copyright (c) 2001, 2003 Wasabi Systems, Inc.
5 * All rights reserved.
6 *
7 * Written by Jason R. Thorpe for Wasabi Systems, Inc.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 * must display the following acknowledgement:
19 * This product includes software developed for the NetBSD Project by
20 * Wasabi Systems, Inc.
21 * 4. The name of Wasabi Systems, Inc. may not be used to endorse
22 * or promote products derived from this software without specific prior
23 * written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY WASABI SYSTEMS, INC. ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
27 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
28 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL WASABI SYSTEMS, INC
29 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
31 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
32 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
33 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
34 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
35 * POSSIBILITY OF SUCH DAMAGE.
36 */
37
38/*
39 * General purpose task queue for sysmon back-ends. This can be
40 * used to run callbacks that require thread context.
41 */
42
43#include <sys/cdefs.h>
44__KERNEL_RCSID(0, "$NetBSD: sysmon_taskq.c,v 1.19 2015/04/28 11:58:49 martin Exp $");
45
46#include <sys/param.h>
47#include <sys/malloc.h>
48#include <sys/queue.h>
49#include <sys/proc.h>
50#include <sys/kthread.h>
51#include <sys/systm.h>
52#include <sys/module.h>
53#include <sys/once.h>
54
55#include <dev/sysmon/sysmon_taskq.h>
56
57struct sysmon_task {
58 TAILQ_ENTRY(sysmon_task) st_list;
59 void (*st_func)(void *);
60 void *st_arg;
61 u_int st_pri;
62};
63
64static TAILQ_HEAD(, sysmon_task) sysmon_task_queue =
65 TAILQ_HEAD_INITIALIZER(sysmon_task_queue);
66
67static kmutex_t sysmon_task_queue_mtx;
68static kmutex_t sysmon_task_queue_init_mtx;
69static kcondvar_t sysmon_task_queue_cv;
70
71static int sysmon_task_queue_initialized;
72static int sysmon_task_queue_cleanup_sem;
73static struct lwp *sysmon_task_queue_lwp;
74static void sysmon_task_queue_thread(void *);
75
76MODULE(MODULE_CLASS_MISC, sysmon_taskq, NULL);
77
78/*
79 * XXX Normally, all initialization would be handled as part of
80 * the module(9) framework. However, there are a number of
81 * users of the sysmon_taskq facility that are not modular,
82 * and these can directly call sysmon_task_queue_init()
83 * directly. To accomodate these non-standard users, we
84 * make sure that sysmon_task_queue_init() handles multiple
85 * invocations. And we also ensure that, if any non-module
86 * user exists, we don't allow the module to be unloaded.
87 * (We can't use module_hold() for this, since the module(9)
88 * framework itself isn't necessarily initialized yet.)
89 */
90
91/*
92 * tq_preinit:
93 *
94 * Early one-time initialization of task-queue
95 */
96
97ONCE_DECL(once_tq);
98
99static int
100tq_preinit(void)
101{
102
103 mutex_init(&sysmon_task_queue_mtx, MUTEX_DEFAULT, IPL_VM);
104 mutex_init(&sysmon_task_queue_init_mtx, MUTEX_DEFAULT, IPL_NONE);
105 cv_init(&sysmon_task_queue_cv, "smtaskq");
106 sysmon_task_queue_initialized = 0;
107
108 return 0;
109}
110
111/*
112 * sysmon_task_queue_init:
113 *
114 * Initialize the sysmon task queue.
115 */
116void
117sysmon_task_queue_init(void)
118{
119 int error;
120
121 (void)RUN_ONCE(&once_tq, tq_preinit);
122
123 mutex_enter(&sysmon_task_queue_init_mtx);
124 if (sysmon_task_queue_initialized++) {
125 mutex_exit(&sysmon_task_queue_init_mtx);
126 return;
127 }
128
129 mutex_exit(&sysmon_task_queue_init_mtx);
130
131 error = kthread_create(PRI_NONE, KTHREAD_MPSAFE, NULL,
132 sysmon_task_queue_thread, NULL, &sysmon_task_queue_lwp, "sysmon");
133 if (error) {
134 printf("Unable to create sysmon task queue thread, "
135 "error = %d\n", error);
136 panic("sysmon_task_queue_init");
137 }
138}
139
140/*
141 * sysmon_task_queue_fini:
142 *
143 * Tear town the sysmon task queue.
144 */
145int
146sysmon_task_queue_fini(void)
147{
148
149 if (sysmon_task_queue_initialized > 1)
150 return EBUSY;
151
152 mutex_enter(&sysmon_task_queue_mtx);
153
154 sysmon_task_queue_cleanup_sem = 1;
155 cv_signal(&sysmon_task_queue_cv);
156
157 while (sysmon_task_queue_cleanup_sem != 0)
158 cv_wait(&sysmon_task_queue_cv,
159 &sysmon_task_queue_mtx);
160
161 mutex_exit(&sysmon_task_queue_mtx);
162
163 return 0;
164}
165
166/*
167 * sysmon_task_queue_thread:
168 *
169 * The sysmon task queue execution thread. We execute callbacks that
170 * have been queued for us.
171 */
172static void
173sysmon_task_queue_thread(void *arg)
174{
175 struct sysmon_task *st;
176
177 /*
178 * Run through all the tasks before we check for the exit
179 * condition; it's probably more important to actually run
180 * all the tasks before we exit.
181 */
182 mutex_enter(&sysmon_task_queue_mtx);
183 for (;;) {
184 st = TAILQ_FIRST(&sysmon_task_queue);
185 if (st != NULL) {
186 TAILQ_REMOVE(&sysmon_task_queue, st, st_list);
187 mutex_exit(&sysmon_task_queue_mtx);
188 (*st->st_func)(st->st_arg);
189 free(st, M_TEMP);
190 mutex_enter(&sysmon_task_queue_mtx);
191 } else {
192 /* Check for the exit condition. */
193 if (sysmon_task_queue_cleanup_sem != 0)
194 break;
195 cv_wait(&sysmon_task_queue_cv, &sysmon_task_queue_mtx);
196 }
197 }
198 /* Time to die. */
199 sysmon_task_queue_cleanup_sem = 0;
200 cv_broadcast(&sysmon_task_queue_cv);
201 mutex_exit(&sysmon_task_queue_mtx);
202 kthread_exit(0);
203}
204
205/*
206 * sysmon_task_queue_sched:
207 *
208 * Schedule a task for deferred execution.
209 */
210int
211sysmon_task_queue_sched(u_int pri, void (*func)(void *), void *arg)
212{
213 struct sysmon_task *st, *lst;
214
215 (void)RUN_ONCE(&once_tq, tq_preinit);
216
217 if (sysmon_task_queue_lwp == NULL)
218 aprint_debug("WARNING: Callback scheduled before sysmon "
219 "task queue thread present\n");
220
221 if (func == NULL)
222 return EINVAL;
223
224 st = malloc(sizeof(*st), M_TEMP, M_NOWAIT);
225 if (st == NULL)
226 return ENOMEM;
227
228 st->st_func = func;
229 st->st_arg = arg;
230 st->st_pri = pri;
231
232 mutex_enter(&sysmon_task_queue_mtx);
233 TAILQ_FOREACH(lst, &sysmon_task_queue, st_list) {
234 if (st->st_pri > lst->st_pri) {
235 TAILQ_INSERT_BEFORE(lst, st, st_list);
236 break;
237 }
238 }
239
240 if (lst == NULL)
241 TAILQ_INSERT_TAIL(&sysmon_task_queue, st, st_list);
242
243 cv_broadcast(&sysmon_task_queue_cv);
244 mutex_exit(&sysmon_task_queue_mtx);
245
246 return 0;
247}
248
249static
250int
251sysmon_taskq_modcmd(modcmd_t cmd, void *arg)
252{
253 int ret;
254
255 switch (cmd) {
256 case MODULE_CMD_INIT:
257 sysmon_task_queue_init();
258 ret = 0;
259 break;
260
261 case MODULE_CMD_FINI:
262 ret = sysmon_task_queue_fini();
263 break;
264
265 case MODULE_CMD_STAT:
266 default:
267 ret = ENOTTY;
268 }
269
270 return ret;
271}
272