FreeBSD/Linux Kernel Cross Reference
sys/geom/geom_event.c
1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 2002 Poul-Henning Kamp
5 * Copyright (c) 2002 Networks Associates Technology, Inc.
6 * All rights reserved.
7 *
8 * This software was developed for the FreeBSD Project by Poul-Henning Kamp
9 * and NAI Labs, the Security Research Division of Network Associates, Inc.
10 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
11 * DARPA CHATS research program.
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. The names of the authors may not be used to endorse or promote
22 * products derived from this software without specific prior written
23 * permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35 * SUCH DAMAGE.
36 */
37
38 /*
39 * XXX: How do we in general know that objects referenced in events
40 * have not been destroyed before we get around to handle the event ?
41 */
42
43 #include <sys/cdefs.h>
44 __FBSDID("$FreeBSD: releng/12.0/sys/geom/geom_event.c 327430 2017-12-31 09:23:52Z cperciva $");
45
46 #include <sys/param.h>
47 #include <sys/malloc.h>
48 #include <sys/systm.h>
49 #include <sys/kernel.h>
50 #include <sys/lock.h>
51 #include <sys/mutex.h>
52 #include <sys/proc.h>
53 #include <sys/errno.h>
54 #include <sys/time.h>
55 #include <geom/geom.h>
56 #include <geom/geom_int.h>
57
58 #include <machine/stdarg.h>
59
60 TAILQ_HEAD(event_tailq_head, g_event);
61
62 static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
63 static u_int g_pending_events;
64 static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
65 static struct mtx g_eventlock;
66 static int g_wither_work;
67
68 #define G_N_EVENTREFS 20
69
70 struct g_event {
71 TAILQ_ENTRY(g_event) events;
72 g_event_t *func;
73 void *arg;
74 int flag;
75 void *ref[G_N_EVENTREFS];
76 };
77
78 #define EV_DONE 0x80000
79 #define EV_WAKEUP 0x40000
80 #define EV_CANCELED 0x20000
81 #define EV_INPROGRESS 0x10000
82
83 void
84 g_waitidle(void)
85 {
86
87 g_topology_assert_not();
88
89 mtx_lock(&g_eventlock);
90 TSWAIT("GEOM events");
91 while (!TAILQ_EMPTY(&g_events))
92 msleep(&g_pending_events, &g_eventlock, PPAUSE,
93 "g_waitidle", hz/5);
94 TSUNWAIT("GEOM events");
95 mtx_unlock(&g_eventlock);
96 curthread->td_pflags &= ~TDP_GEOM;
97 }
98
99 #if 0
100 void
101 g_waitidlelock(void)
102 {
103
104 g_topology_assert();
105 mtx_lock(&g_eventlock);
106 while (!TAILQ_EMPTY(&g_events)) {
107 g_topology_unlock();
108 msleep(&g_pending_events, &g_eventlock, PPAUSE,
109 "g_waitidlel", hz/5);
110 g_topology_lock();
111 }
112 mtx_unlock(&g_eventlock);
113 }
114 #endif
115
116 struct g_attrchanged_args {
117 struct g_provider *pp;
118 const char *attr;
119 };
120
121 static void
122 g_attr_changed_event(void *arg, int flag)
123 {
124 struct g_attrchanged_args *args;
125 struct g_provider *pp;
126 struct g_consumer *cp;
127 struct g_consumer *next_cp;
128
129 args = arg;
130 pp = args->pp;
131
132 g_topology_assert();
133 if (flag != EV_CANCEL && g_shutdown == 0) {
134
135 /*
136 * Tell all consumers of the change.
137 */
138 LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, next_cp) {
139 if (cp->geom->attrchanged != NULL)
140 cp->geom->attrchanged(cp, args->attr);
141 }
142 }
143 g_free(args);
144 }
145
146 int
147 g_attr_changed(struct g_provider *pp, const char *attr, int flag)
148 {
149 struct g_attrchanged_args *args;
150 int error;
151
152 args = g_malloc(sizeof *args, flag);
153 if (args == NULL)
154 return (ENOMEM);
155 args->pp = pp;
156 args->attr = attr;
157 error = g_post_event(g_attr_changed_event, args, flag, pp, NULL);
158 if (error != 0)
159 g_free(args);
160 return (error);
161 }
162
163 void
164 g_orphan_provider(struct g_provider *pp, int error)
165 {
166
167 /* G_VALID_PROVIDER(pp) We likely lack topology lock */
168 g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
169 pp, pp->name, error);
170 KASSERT(error != 0,
171 ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
172 pp, pp->name));
173
174 pp->error = error;
175 mtx_lock(&g_eventlock);
176 KASSERT(!(pp->flags & G_PF_ORPHAN),
177 ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
178 pp->flags |= G_PF_ORPHAN;
179 TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
180 mtx_unlock(&g_eventlock);
181 wakeup(&g_wait_event);
182 }
183
184 /*
185 * This function is called once on each provider which the event handler
186 * finds on its g_doorstep.
187 */
188
189 static void
190 g_orphan_register(struct g_provider *pp)
191 {
192 struct g_consumer *cp, *cp2;
193 int wf;
194
195 g_topology_assert();
196 G_VALID_PROVIDER(pp);
197 g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
198
199 g_cancel_event(pp);
200
201 wf = pp->flags & G_PF_WITHER;
202 pp->flags &= ~G_PF_WITHER;
203
204 /*
205 * Tell all consumers the bad news.
206 * Don't be surprised if they self-destruct.
207 */
208 LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, cp2) {
209 KASSERT(cp->geom->orphan != NULL,
210 ("geom %s has no orphan, class %s",
211 cp->geom->name, cp->geom->class->name));
212 /*
213 * XXX: g_dev_orphan method does deferred destroying
214 * and it is possible, that other event could already
215 * call the orphan method. Check consumer's flags to
216 * do not schedule it twice.
217 */
218 if (cp->flags & G_CF_ORPHAN)
219 continue;
220 cp->flags |= G_CF_ORPHAN;
221 cp->geom->orphan(cp);
222 }
223 if (LIST_EMPTY(&pp->consumers) && wf)
224 g_destroy_provider(pp);
225 else
226 pp->flags |= wf;
227 #ifdef notyet
228 cp = LIST_FIRST(&pp->consumers);
229 if (cp != NULL)
230 return;
231 if (pp->geom->flags & G_GEOM_WITHER)
232 g_destroy_provider(pp);
233 #endif
234 }
235
236 static int
237 one_event(void)
238 {
239 struct g_event *ep;
240 struct g_provider *pp;
241
242 g_topology_assert();
243 mtx_lock(&g_eventlock);
244 TAILQ_FOREACH(pp, &g_doorstep, orphan) {
245 if (pp->nstart == pp->nend)
246 break;
247 }
248 if (pp != NULL) {
249 G_VALID_PROVIDER(pp);
250 TAILQ_REMOVE(&g_doorstep, pp, orphan);
251 mtx_unlock(&g_eventlock);
252 g_orphan_register(pp);
253 return (1);
254 }
255
256 ep = TAILQ_FIRST(&g_events);
257 if (ep == NULL) {
258 wakeup(&g_pending_events);
259 return (0);
260 }
261 if (ep->flag & EV_INPROGRESS) {
262 mtx_unlock(&g_eventlock);
263 return (1);
264 }
265 ep->flag |= EV_INPROGRESS;
266 mtx_unlock(&g_eventlock);
267 g_topology_assert();
268 ep->func(ep->arg, 0);
269 g_topology_assert();
270 mtx_lock(&g_eventlock);
271 TSRELEASE("GEOM events");
272 TAILQ_REMOVE(&g_events, ep, events);
273 ep->flag &= ~EV_INPROGRESS;
274 if (ep->flag & EV_WAKEUP) {
275 ep->flag |= EV_DONE;
276 mtx_unlock(&g_eventlock);
277 wakeup(ep);
278 } else {
279 mtx_unlock(&g_eventlock);
280 g_free(ep);
281 }
282 return (1);
283 }
284
285 void
286 g_run_events()
287 {
288
289 for (;;) {
290 g_topology_lock();
291 while (one_event())
292 ;
293 mtx_assert(&g_eventlock, MA_OWNED);
294 if (g_wither_work) {
295 g_wither_work = 0;
296 mtx_unlock(&g_eventlock);
297 g_wither_washer();
298 g_topology_unlock();
299 } else {
300 g_topology_unlock();
301 msleep(&g_wait_event, &g_eventlock, PRIBIO | PDROP,
302 "-", TAILQ_EMPTY(&g_doorstep) ? 0 : hz / 10);
303 }
304 }
305 /* NOTREACHED */
306 }
307
308 void
309 g_cancel_event(void *ref)
310 {
311 struct g_event *ep, *epn;
312 struct g_provider *pp;
313 u_int n;
314
315 mtx_lock(&g_eventlock);
316 TAILQ_FOREACH(pp, &g_doorstep, orphan) {
317 if (pp != ref)
318 continue;
319 TAILQ_REMOVE(&g_doorstep, pp, orphan);
320 break;
321 }
322 TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
323 if (ep->flag & EV_INPROGRESS)
324 continue;
325 for (n = 0; n < G_N_EVENTREFS; n++) {
326 if (ep->ref[n] == NULL)
327 break;
328 if (ep->ref[n] != ref)
329 continue;
330 TSRELEASE("GEOM events");
331 TAILQ_REMOVE(&g_events, ep, events);
332 ep->func(ep->arg, EV_CANCEL);
333 mtx_assert(&g_eventlock, MA_OWNED);
334 if (ep->flag & EV_WAKEUP) {
335 ep->flag |= (EV_DONE|EV_CANCELED);
336 wakeup(ep);
337 } else {
338 g_free(ep);
339 }
340 break;
341 }
342 }
343 if (TAILQ_EMPTY(&g_events))
344 wakeup(&g_pending_events);
345 mtx_unlock(&g_eventlock);
346 }
347
348 static int
349 g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
350 {
351 struct g_event *ep;
352 void *p;
353 u_int n;
354
355 g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
356 func, arg, flag, wuflag);
357 KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
358 ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
359 ep = g_malloc(sizeof *ep, flag | M_ZERO);
360 if (ep == NULL)
361 return (ENOMEM);
362 ep->flag = wuflag;
363 for (n = 0; n < G_N_EVENTREFS; n++) {
364 p = va_arg(ap, void *);
365 if (p == NULL)
366 break;
367 g_trace(G_T_TOPOLOGY, " ref %p", p);
368 ep->ref[n] = p;
369 }
370 KASSERT(p == NULL, ("Too many references to event"));
371 ep->func = func;
372 ep->arg = arg;
373 mtx_lock(&g_eventlock);
374 TSHOLD("GEOM events");
375 TAILQ_INSERT_TAIL(&g_events, ep, events);
376 mtx_unlock(&g_eventlock);
377 wakeup(&g_wait_event);
378 if (epp != NULL)
379 *epp = ep;
380 curthread->td_pflags |= TDP_GEOM;
381 return (0);
382 }
383
384 int
385 g_post_event(g_event_t *func, void *arg, int flag, ...)
386 {
387 va_list ap;
388 int i;
389
390 KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
391 ("Wrong flag to g_post_event"));
392 va_start(ap, flag);
393 i = g_post_event_x(func, arg, flag, 0, NULL, ap);
394 va_end(ap);
395 return (i);
396 }
397
398 void
399 g_do_wither()
400 {
401
402 mtx_lock(&g_eventlock);
403 g_wither_work = 1;
404 mtx_unlock(&g_eventlock);
405 wakeup(&g_wait_event);
406 }
407
408 /*
409 * XXX: It might actually be useful to call this function with topology held.
410 * XXX: This would ensure that the event gets created before anything else
411 * XXX: changes. At present all users have a handle on things in some other
412 * XXX: way, so this remains an XXX for now.
413 */
414
415 int
416 g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
417 {
418 va_list ap;
419 struct g_event *ep;
420 int error;
421
422 g_topology_assert_not();
423 KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
424 ("Wrong flag to g_post_event"));
425 va_start(ap, flag);
426 error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
427 va_end(ap);
428 if (error)
429 return (error);
430
431 mtx_lock(&g_eventlock);
432 while (!(ep->flag & EV_DONE))
433 msleep(ep, &g_eventlock, PRIBIO, "g_waitfor_event", hz);
434 if (ep->flag & EV_CANCELED)
435 error = EAGAIN;
436 mtx_unlock(&g_eventlock);
437
438 g_free(ep);
439 return (error);
440 }
441
442 void
443 g_event_init()
444 {
445
446 mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
447 }
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