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: src/sys/geom/geom_event.c,v 1.50.2.1 2005/02/28 19:32:24 phk Exp $");
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 <machine/stdarg.h>
52 #include <sys/errno.h>
53 #include <sys/time.h>
54 #include <geom/geom.h>
55 #include <geom/geom_int.h>
56
57 TAILQ_HEAD(event_tailq_head, g_event);
58
59 static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
60 static u_int g_pending_events;
61 static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
62 static struct mtx g_eventlock;
63 static int g_wither_work;
64
65 #define G_N_EVENTREFS 20
66
67 struct g_event {
68 TAILQ_ENTRY(g_event) events;
69 g_event_t *func;
70 void *arg;
71 int flag;
72 void *ref[G_N_EVENTREFS];
73 };
74
75 #define EV_DONE 0x80000
76 #define EV_WAKEUP 0x40000
77 #define EV_CANCELED 0x20000
78
79 void
80 g_waitidle(void)
81 {
82
83 g_topology_assert_not();
84 mtx_assert(&Giant, MA_NOTOWNED);
85
86 while (g_pending_events)
87 tsleep(&g_pending_events, PPAUSE, "g_waitidle", hz/5);
88 curthread->td_pflags &= ~TDP_GEOM;
89 }
90
91 void
92 g_orphan_provider(struct g_provider *pp, int error)
93 {
94
95 /* G_VALID_PROVIDER(pp) We likely lack topology lock */
96 g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
97 pp, pp->name, error);
98 KASSERT(error != 0,
99 ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
100 pp, pp->name));
101
102 pp->error = error;
103 mtx_lock(&g_eventlock);
104 KASSERT(!(pp->flags & G_PF_ORPHAN),
105 ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
106 pp->flags |= G_PF_ORPHAN;
107 TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
108 mtx_unlock(&g_eventlock);
109 wakeup(&g_wait_event);
110 }
111
112 /*
113 * This function is called once on each provider which the event handler
114 * finds on its g_doorstep.
115 */
116
117 static void
118 g_orphan_register(struct g_provider *pp)
119 {
120 struct g_consumer *cp, *cp2;
121 int wf;
122
123 g_topology_assert();
124 G_VALID_PROVIDER(pp);
125 g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
126
127 wf = pp->flags & G_PF_WITHER;
128 pp->flags &= ~G_PF_WITHER;
129
130 /*
131 * Tell all consumers the bad news.
132 * Don't be surprised if they self-destruct.
133 */
134 cp = LIST_FIRST(&pp->consumers);
135 while (cp != NULL) {
136 cp2 = LIST_NEXT(cp, consumers);
137 KASSERT(cp->geom->orphan != NULL,
138 ("geom %s has no orphan, class %s",
139 cp->geom->name, cp->geom->class->name));
140 cp->geom->orphan(cp);
141 cp = cp2;
142 }
143 if (LIST_EMPTY(&pp->consumers) && wf)
144 g_destroy_provider(pp);
145 else
146 pp->flags |= wf;
147 #ifdef notyet
148 cp = LIST_FIRST(&pp->consumers);
149 if (cp != NULL)
150 return;
151 if (pp->geom->flags & G_GEOM_WITHER)
152 g_destroy_provider(pp);
153 #endif
154 }
155
156 static int
157 one_event(void)
158 {
159 struct g_event *ep;
160 struct g_provider *pp;
161
162 g_topology_lock();
163 for (;;) {
164 mtx_lock(&g_eventlock);
165 pp = TAILQ_FIRST(&g_doorstep);
166 if (pp != NULL) {
167 G_VALID_PROVIDER(pp);
168 TAILQ_REMOVE(&g_doorstep, pp, orphan);
169 }
170 mtx_unlock(&g_eventlock);
171 if (pp == NULL)
172 break;
173 g_orphan_register(pp);
174 }
175 mtx_lock(&g_eventlock);
176 ep = TAILQ_FIRST(&g_events);
177 if (ep == NULL) {
178 mtx_unlock(&g_eventlock);
179 g_topology_unlock();
180 return (0);
181 }
182 TAILQ_REMOVE(&g_events, ep, events);
183 mtx_unlock(&g_eventlock);
184 g_topology_assert();
185 ep->func(ep->arg, 0);
186 g_topology_assert();
187 if (ep->flag & EV_WAKEUP) {
188 ep->flag |= EV_DONE;
189 wakeup(ep);
190 } else {
191 g_free(ep);
192 }
193 g_pending_events--;
194 if (g_pending_events == 0)
195 wakeup(&g_pending_events);
196 g_topology_unlock();
197 return (1);
198 }
199
200 void
201 g_run_events()
202 {
203 int i;
204
205 while (one_event())
206 ;
207 g_topology_lock();
208 i = g_wither_work;
209 while (i) {
210 i = g_wither_washer();
211 g_wither_work = i & 1;
212 i &= 2;
213 }
214 g_topology_unlock();
215 }
216
217 void
218 g_cancel_event(void *ref)
219 {
220 struct g_event *ep, *epn;
221 struct g_provider *pp;
222 u_int n;
223
224 mtx_lock(&g_eventlock);
225 TAILQ_FOREACH(pp, &g_doorstep, orphan) {
226 if (pp != ref)
227 continue;
228 TAILQ_REMOVE(&g_doorstep, pp, orphan);
229 break;
230 }
231 for (ep = TAILQ_FIRST(&g_events); ep != NULL; ep = epn) {
232 epn = TAILQ_NEXT(ep, events);
233 for (n = 0; n < G_N_EVENTREFS; n++) {
234 if (ep->ref[n] == NULL)
235 break;
236 if (ep->ref[n] == ref) {
237 TAILQ_REMOVE(&g_events, ep, events);
238 ep->func(ep->arg, EV_CANCEL);
239 if (ep->flag & EV_WAKEUP) {
240 ep->flag |= EV_DONE;
241 ep->flag |= EV_CANCELED;
242 wakeup(ep);
243 } else {
244 g_free(ep);
245 }
246 if (--g_pending_events == 0)
247 wakeup(&g_pending_events);
248 break;
249 }
250 }
251 }
252 mtx_unlock(&g_eventlock);
253 }
254
255 static int
256 g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
257 {
258 struct g_event *ep;
259 void *p;
260 u_int n;
261
262 g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
263 func, arg, flag, wakeup);
264 KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
265 ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
266 ep = g_malloc(sizeof *ep, flag | M_ZERO);
267 if (ep == NULL)
268 return (ENOMEM);
269 ep->flag = wuflag;
270 for (n = 0; n < G_N_EVENTREFS; n++) {
271 p = va_arg(ap, void *);
272 if (p == NULL)
273 break;
274 g_trace(G_T_TOPOLOGY, " ref %p", p);
275 ep->ref[n] = p;
276 }
277 KASSERT(p == NULL, ("Too many references to event"));
278 ep->func = func;
279 ep->arg = arg;
280 mtx_lock(&g_eventlock);
281 g_pending_events++;
282 TAILQ_INSERT_TAIL(&g_events, ep, events);
283 mtx_unlock(&g_eventlock);
284 wakeup(&g_wait_event);
285 if (epp != NULL)
286 *epp = ep;
287 curthread->td_pflags |= TDP_GEOM;
288 return (0);
289 }
290
291 int
292 g_post_event(g_event_t *func, void *arg, int flag, ...)
293 {
294 va_list ap;
295 int i;
296
297 KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
298 ("Wrong flag to g_post_event"));
299 va_start(ap, flag);
300 i = g_post_event_x(func, arg, flag, 0, NULL, ap);
301 va_end(ap);
302 return (i);
303 }
304
305 void
306 g_do_wither() {
307
308 g_wither_work = 1;
309 wakeup(&g_wait_event);
310 }
311
312 /*
313 * XXX: It might actually be useful to call this function with topology held.
314 * XXX: This would ensure that the event gets created before anything else
315 * XXX: changes. At present all users have a handle on things in some other
316 * XXX: way, so this remains an XXX for now.
317 */
318
319 int
320 g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
321 {
322 va_list ap;
323 struct g_event *ep;
324 int error;
325
326 g_topology_assert_not();
327 KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
328 ("Wrong flag to g_post_event"));
329 va_start(ap, flag);
330 error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
331 va_end(ap);
332 if (error)
333 return (error);
334 do
335 tsleep(ep, PRIBIO, "g_waitfor_event", hz);
336 while (!(ep->flag & EV_DONE));
337 if (ep->flag & EV_CANCELED)
338 error = EAGAIN;
339 g_free(ep);
340 return (error);
341 }
342
343 void
344 g_event_init()
345 {
346
347 mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
348 }
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