1 /* $NetBSD: sysmon_taskq.c,v 1.23 2021/12/31 14:29:14 riastradh 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 1.23 2021/12/31 14:29:14 riastradh 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
57 struct 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
64 static TAILQ_HEAD(, sysmon_task) sysmon_task_queue =
65 TAILQ_HEAD_INITIALIZER(sysmon_task_queue);
66
67 static kmutex_t sysmon_task_queue_mtx;
68 static kmutex_t sysmon_task_queue_init_mtx;
69 static kcondvar_t sysmon_task_queue_cv;
70
71 static int sysmon_task_queue_initialized;
72 static int sysmon_task_queue_cleanup_sem;
73 static struct lwp *sysmon_task_queue_lwp;
74 static void sysmon_task_queue_thread(void *);
75
76 MODULE(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 accommodate 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
97 ONCE_DECL(once_tq);
98
99 static int
tq_preinit(void)100 tq_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 */
116 void
sysmon_task_queue_init(void)117 sysmon_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 */
145 int
sysmon_task_queue_fini(void)146 sysmon_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 */
172 static void
sysmon_task_queue_thread(void * arg)173 sysmon_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 static void
sysmon_task_queue_sched_task(struct sysmon_task * st)206 sysmon_task_queue_sched_task(struct sysmon_task *st)
207 {
208 struct sysmon_task *lst;
209
210 mutex_enter(&sysmon_task_queue_mtx);
211 TAILQ_FOREACH(lst, &sysmon_task_queue, st_list) {
212 if (st->st_pri > lst->st_pri) {
213 TAILQ_INSERT_BEFORE(lst, st, st_list);
214 break;
215 }
216 }
217
218 if (lst == NULL)
219 TAILQ_INSERT_TAIL(&sysmon_task_queue, st, st_list);
220
221 cv_broadcast(&sysmon_task_queue_cv);
222 mutex_exit(&sysmon_task_queue_mtx);
223 }
224
225 /*
226 * sysmon_task_queue_sched:
227 *
228 * Schedule a task for deferred execution.
229 */
230 int
sysmon_task_queue_sched(u_int pri,void (* func)(void *),void * arg)231 sysmon_task_queue_sched(u_int pri, void (*func)(void *), void *arg)
232 {
233 struct sysmon_task *st;
234
235 (void)RUN_ONCE(&once_tq, tq_preinit);
236
237 if (sysmon_task_queue_lwp == NULL)
238 aprint_debug("WARNING: Callback scheduled before sysmon "
239 "task queue thread present\n");
240
241 if (func == NULL)
242 return EINVAL;
243
244 st = malloc(sizeof(*st), M_TEMP, M_NOWAIT);
245 if (st == NULL)
246 return ENOMEM;
247
248 st->st_func = func;
249 st->st_arg = arg;
250 st->st_pri = pri;
251
252 sysmon_task_queue_sched_task(st);
253
254 return 0;
255 }
256
257 struct tqbarrier {
258 kmutex_t lock;
259 kcondvar_t cv;
260 bool done;
261 };
262
263 static void
tqbarrier_task(void * cookie)264 tqbarrier_task(void *cookie)
265 {
266 struct tqbarrier *bar = cookie;
267
268 mutex_enter(&bar->lock);
269 bar->done = true;
270 cv_broadcast(&bar->cv);
271 mutex_exit(&bar->lock);
272 }
273
274 /*
275 * sysmon_task_queue_barrier:
276 *
277 * Wait for the completion of all tasks at priority pri or lower
278 * currently queued at the time of the call.
279 */
280 void
sysmon_task_queue_barrier(u_int pri)281 sysmon_task_queue_barrier(u_int pri)
282 {
283 struct sysmon_task *st;
284 struct tqbarrier bar;
285
286 (void)RUN_ONCE(&once_tq, tq_preinit);
287
288 KASSERT(sysmon_task_queue_lwp);
289 KASSERT(curlwp != sysmon_task_queue_lwp);
290
291 mutex_init(&bar.lock, MUTEX_DEFAULT, IPL_NONE);
292 cv_init(&bar.cv, "sysmontq");
293 bar.done = false;
294
295 st = malloc(sizeof(*st), M_TEMP, M_WAITOK);
296 st->st_func = &tqbarrier_task;
297 st->st_arg = &bar;
298 st->st_pri = pri;
299
300 sysmon_task_queue_sched_task(st);
301
302 mutex_enter(&bar.lock);
303 while (!bar.done)
304 cv_wait(&bar.cv, &bar.lock);
305 mutex_exit(&bar.lock);
306
307 cv_destroy(&bar.cv);
308 mutex_destroy(&bar.lock);
309 }
310
311 static int
sysmon_taskq_modcmd(modcmd_t cmd,void * arg)312 sysmon_taskq_modcmd(modcmd_t cmd, void *arg)
313 {
314 int ret;
315
316 switch (cmd) {
317 case MODULE_CMD_INIT:
318 sysmon_task_queue_init();
319 ret = 0;
320 break;
321 case MODULE_CMD_FINI:
322 ret = sysmon_task_queue_fini();
323 break;
324 case MODULE_CMD_STAT:
325 default:
326 ret = ENOTTY;
327 }
328
329 return ret;
330 }
331