FreeBSD/Linux Kernel Cross Reference
sys/geom/geom_event.c
1 /*-
2 * Copyright (c) 2002 Poul-Henning Kamp
3 * Copyright (c) 2002 Networks Associates Technology, Inc.
4 * All rights reserved.
5 *
6 * This software was developed for the FreeBSD Project by Poul-Henning Kamp
7 * and NAI Labs, the Security Research Division of Network Associates, Inc.
8 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
9 * DARPA CHATS research program.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 * 3. The names of the authors may not be used to endorse or promote
20 * products derived from this software without specific prior written
21 * permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36 /*
37 * XXX: How do we in general know that objects referenced in events
38 * have not been destroyed before we get around to handle the event ?
39 */
40
41 #include <sys/cdefs.h>
42 __FBSDID("$FreeBSD: releng/8.3/sys/geom/geom_event.c 227227 2011-11-06 16:58:17Z mav $");
43
44 #include <sys/param.h>
45 #include <sys/malloc.h>
46 #include <sys/systm.h>
47 #include <sys/kernel.h>
48 #include <sys/lock.h>
49 #include <sys/mutex.h>
50 #include <sys/proc.h>
51 #include <sys/errno.h>
52 #include <sys/time.h>
53 #include <geom/geom.h>
54 #include <geom/geom_int.h>
55
56 #include <machine/stdarg.h>
57
58 TAILQ_HEAD(event_tailq_head, g_event);
59
60 static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
61 static u_int g_pending_events;
62 static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
63 static struct mtx g_eventlock;
64 static int g_wither_work;
65
66 #define G_N_EVENTREFS 20
67
68 struct g_event {
69 TAILQ_ENTRY(g_event) events;
70 g_event_t *func;
71 void *arg;
72 int flag;
73 void *ref[G_N_EVENTREFS];
74 };
75
76 #define EV_DONE 0x80000
77 #define EV_WAKEUP 0x40000
78 #define EV_CANCELED 0x20000
79 #define EV_INPROGRESS 0x10000
80
81 void
82 g_waitidle(void)
83 {
84
85 g_topology_assert_not();
86 mtx_assert(&Giant, MA_NOTOWNED);
87
88 mtx_lock(&g_eventlock);
89 while (!TAILQ_EMPTY(&g_events))
90 msleep(&g_pending_events, &g_eventlock, PPAUSE,
91 "g_waitidle", hz/5);
92 mtx_unlock(&g_eventlock);
93 curthread->td_pflags &= ~TDP_GEOM;
94 }
95
96 #if 0
97 void
98 g_waitidlelock(void)
99 {
100
101 g_topology_assert();
102 mtx_lock(&g_eventlock);
103 while (!TAILQ_EMPTY(&g_events)) {
104 g_topology_unlock();
105 msleep(&g_pending_events, &g_eventlock, PPAUSE,
106 "g_waitidlel", hz/5);
107 g_topology_lock();
108 }
109 mtx_unlock(&g_eventlock);
110 }
111 #endif
112
113 void
114 g_orphan_provider(struct g_provider *pp, int error)
115 {
116
117 /* G_VALID_PROVIDER(pp) We likely lack topology lock */
118 g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
119 pp, pp->name, error);
120 KASSERT(error != 0,
121 ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
122 pp, pp->name));
123
124 pp->error = error;
125 mtx_lock(&g_eventlock);
126 KASSERT(!(pp->flags & G_PF_ORPHAN),
127 ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
128 pp->flags |= G_PF_ORPHAN;
129 TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
130 mtx_unlock(&g_eventlock);
131 wakeup(&g_wait_event);
132 }
133
134 /*
135 * This function is called once on each provider which the event handler
136 * finds on its g_doorstep.
137 */
138
139 static void
140 g_orphan_register(struct g_provider *pp)
141 {
142 struct g_consumer *cp, *cp2;
143 int wf;
144
145 g_topology_assert();
146 G_VALID_PROVIDER(pp);
147 g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
148
149 g_cancel_event(pp);
150
151 wf = pp->flags & G_PF_WITHER;
152 pp->flags &= ~G_PF_WITHER;
153
154 /*
155 * Tell all consumers the bad news.
156 * Don't be surprised if they self-destruct.
157 */
158 cp = LIST_FIRST(&pp->consumers);
159 while (cp != NULL) {
160 cp2 = LIST_NEXT(cp, consumers);
161 KASSERT(cp->geom->orphan != NULL,
162 ("geom %s has no orphan, class %s",
163 cp->geom->name, cp->geom->class->name));
164 cp->geom->orphan(cp);
165 cp = cp2;
166 }
167 if (LIST_EMPTY(&pp->consumers) && wf)
168 g_destroy_provider(pp);
169 else
170 pp->flags |= wf;
171 #ifdef notyet
172 cp = LIST_FIRST(&pp->consumers);
173 if (cp != NULL)
174 return;
175 if (pp->geom->flags & G_GEOM_WITHER)
176 g_destroy_provider(pp);
177 #endif
178 }
179
180 static int
181 one_event(void)
182 {
183 struct g_event *ep;
184 struct g_provider *pp;
185
186 g_topology_assert();
187 mtx_lock(&g_eventlock);
188 TAILQ_FOREACH(pp, &g_doorstep, orphan) {
189 if (pp->nstart == pp->nend)
190 break;
191 }
192 if (pp != NULL) {
193 G_VALID_PROVIDER(pp);
194 TAILQ_REMOVE(&g_doorstep, pp, orphan);
195 mtx_unlock(&g_eventlock);
196 g_orphan_register(pp);
197 return (1);
198 }
199
200 ep = TAILQ_FIRST(&g_events);
201 if (ep == NULL) {
202 wakeup(&g_pending_events);
203 return (0);
204 }
205 if (ep->flag & EV_INPROGRESS) {
206 mtx_unlock(&g_eventlock);
207 return (1);
208 }
209 ep->flag |= EV_INPROGRESS;
210 mtx_unlock(&g_eventlock);
211 g_topology_assert();
212 ep->func(ep->arg, 0);
213 g_topology_assert();
214 mtx_lock(&g_eventlock);
215 TAILQ_REMOVE(&g_events, ep, events);
216 ep->flag &= ~EV_INPROGRESS;
217 if (ep->flag & EV_WAKEUP) {
218 ep->flag |= EV_DONE;
219 mtx_unlock(&g_eventlock);
220 wakeup(ep);
221 } else {
222 mtx_unlock(&g_eventlock);
223 g_free(ep);
224 }
225 return (1);
226 }
227
228 void
229 g_run_events()
230 {
231 int i;
232
233 for (;;) {
234 g_topology_lock();
235 while (one_event())
236 ;
237 mtx_assert(&g_eventlock, MA_OWNED);
238 i = g_wither_work;
239 if (i) {
240 mtx_unlock(&g_eventlock);
241 while (i) {
242 i = g_wither_washer();
243 g_wither_work = i & 1;
244 i &= 2;
245 }
246 g_topology_unlock();
247 } else {
248 g_topology_unlock();
249 msleep(&g_wait_event, &g_eventlock, PRIBIO | PDROP,
250 "-", TAILQ_EMPTY(&g_doorstep) ? 0 : hz / 10);
251 }
252 }
253 /* NOTREACHED */
254 }
255
256 void
257 g_cancel_event(void *ref)
258 {
259 struct g_event *ep, *epn;
260 struct g_provider *pp;
261 u_int n;
262
263 mtx_lock(&g_eventlock);
264 TAILQ_FOREACH(pp, &g_doorstep, orphan) {
265 if (pp != ref)
266 continue;
267 TAILQ_REMOVE(&g_doorstep, pp, orphan);
268 break;
269 }
270 TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
271 if (ep->flag & EV_INPROGRESS)
272 continue;
273 for (n = 0; n < G_N_EVENTREFS; n++) {
274 if (ep->ref[n] == NULL)
275 break;
276 if (ep->ref[n] != ref)
277 continue;
278 TAILQ_REMOVE(&g_events, ep, events);
279 ep->func(ep->arg, EV_CANCEL);
280 mtx_assert(&g_eventlock, MA_OWNED);
281 if (ep->flag & EV_WAKEUP) {
282 ep->flag |= (EV_DONE|EV_CANCELED);
283 wakeup(ep);
284 } else {
285 g_free(ep);
286 }
287 break;
288 }
289 }
290 if (TAILQ_EMPTY(&g_events))
291 wakeup(&g_pending_events);
292 mtx_unlock(&g_eventlock);
293 }
294
295 static int
296 g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
297 {
298 struct g_event *ep;
299 void *p;
300 u_int n;
301
302 g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
303 func, arg, flag, wuflag);
304 KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
305 ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
306 ep = g_malloc(sizeof *ep, flag | M_ZERO);
307 if (ep == NULL)
308 return (ENOMEM);
309 ep->flag = wuflag;
310 for (n = 0; n < G_N_EVENTREFS; n++) {
311 p = va_arg(ap, void *);
312 if (p == NULL)
313 break;
314 g_trace(G_T_TOPOLOGY, " ref %p", p);
315 ep->ref[n] = p;
316 }
317 KASSERT(p == NULL, ("Too many references to event"));
318 ep->func = func;
319 ep->arg = arg;
320 mtx_lock(&g_eventlock);
321 TAILQ_INSERT_TAIL(&g_events, ep, events);
322 mtx_unlock(&g_eventlock);
323 wakeup(&g_wait_event);
324 if (epp != NULL)
325 *epp = ep;
326 curthread->td_pflags |= TDP_GEOM;
327 return (0);
328 }
329
330 int
331 g_post_event(g_event_t *func, void *arg, int flag, ...)
332 {
333 va_list ap;
334 int i;
335
336 KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
337 ("Wrong flag to g_post_event"));
338 va_start(ap, flag);
339 i = g_post_event_x(func, arg, flag, 0, NULL, ap);
340 va_end(ap);
341 return (i);
342 }
343
344 void
345 g_do_wither()
346 {
347
348 mtx_lock(&g_eventlock);
349 g_wither_work = 1;
350 mtx_unlock(&g_eventlock);
351 wakeup(&g_wait_event);
352 }
353
354 /*
355 * XXX: It might actually be useful to call this function with topology held.
356 * XXX: This would ensure that the event gets created before anything else
357 * XXX: changes. At present all users have a handle on things in some other
358 * XXX: way, so this remains an XXX for now.
359 */
360
361 int
362 g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
363 {
364 va_list ap;
365 struct g_event *ep;
366 int error;
367
368 g_topology_assert_not();
369 KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
370 ("Wrong flag to g_post_event"));
371 va_start(ap, flag);
372 error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
373 va_end(ap);
374 if (error)
375 return (error);
376
377 mtx_lock(&g_eventlock);
378 while (!(ep->flag & EV_DONE))
379 msleep(ep, &g_eventlock, PRIBIO, "g_waitfor_event", hz);
380 if (ep->flag & EV_CANCELED)
381 error = EAGAIN;
382 mtx_unlock(&g_eventlock);
383
384 g_free(ep);
385 return (error);
386 }
387
388 void
389 g_event_init()
390 {
391
392 mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
393 }
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