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("$FreeBSD$");
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(struct thread *td)
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", 0);
94 TSUNWAIT("GEOM events");
95 mtx_unlock(&g_eventlock);
96 td->td_pflags &= ~TDP_GEOM;
97 }
98
99 static void
100 ast_geom(struct thread *td, int tda __unused)
101 {
102 /*
103 * If this thread tickled GEOM, we need to wait for the giggling to
104 * stop before we return to userland.
105 */
106 g_waitidle(td);
107 }
108
109 static void
110 geom_event_init(void *arg __unused)
111 {
112 ast_register(TDA_GEOM, ASTR_ASTF_REQUIRED | ASTR_TDP | ASTR_KCLEAR,
113 TDP_GEOM, ast_geom);
114 }
115 SYSINIT(geom_event, SI_SUB_INTRINSIC, SI_ORDER_ANY, geom_event_init, NULL);
116
117 struct g_attrchanged_args {
118 struct g_provider *pp;
119 const char *attr;
120 };
121
122 static void
123 g_attr_changed_event(void *arg, int flag)
124 {
125 struct g_attrchanged_args *args;
126 struct g_provider *pp;
127 struct g_consumer *cp;
128 struct g_consumer *next_cp;
129
130 args = arg;
131 pp = args->pp;
132
133 g_topology_assert();
134 if (flag != EV_CANCEL && g_shutdown == 0) {
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 pp = TAILQ_FIRST(&g_doorstep);
245 if (pp != NULL) {
246 G_VALID_PROVIDER(pp);
247 TAILQ_REMOVE(&g_doorstep, pp, orphan);
248 mtx_unlock(&g_eventlock);
249 g_orphan_register(pp);
250 return (1);
251 }
252
253 ep = TAILQ_FIRST(&g_events);
254 if (ep == NULL) {
255 wakeup(&g_pending_events);
256 return (0);
257 }
258 ep->flag |= EV_INPROGRESS;
259 mtx_unlock(&g_eventlock);
260 g_topology_assert();
261 ep->func(ep->arg, 0);
262 g_topology_assert();
263 mtx_lock(&g_eventlock);
264 TSRELEASE("GEOM events");
265 TAILQ_REMOVE(&g_events, ep, events);
266 ep->flag &= ~EV_INPROGRESS;
267 if (ep->flag & EV_WAKEUP) {
268 ep->flag |= EV_DONE;
269 wakeup(ep);
270 mtx_unlock(&g_eventlock);
271 } else {
272 mtx_unlock(&g_eventlock);
273 g_free(ep);
274 }
275 return (1);
276 }
277
278 void
279 g_run_events(void)
280 {
281
282 for (;;) {
283 g_topology_lock();
284 while (one_event())
285 ;
286 mtx_assert(&g_eventlock, MA_OWNED);
287 if (g_wither_work) {
288 g_wither_work = 0;
289 mtx_unlock(&g_eventlock);
290 g_wither_washer();
291 g_topology_unlock();
292 } else {
293 g_topology_unlock();
294 msleep(&g_wait_event, &g_eventlock, PRIBIO | PDROP,
295 "-", 0);
296 }
297 }
298 /* NOTREACHED */
299 }
300
301 void
302 g_cancel_event(void *ref)
303 {
304 struct g_event *ep, *epn;
305 struct g_provider *pp;
306 u_int n;
307
308 mtx_lock(&g_eventlock);
309 TAILQ_FOREACH(pp, &g_doorstep, orphan) {
310 if (pp != ref)
311 continue;
312 TAILQ_REMOVE(&g_doorstep, pp, orphan);
313 break;
314 }
315 TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
316 if (ep->flag & EV_INPROGRESS)
317 continue;
318 for (n = 0; n < G_N_EVENTREFS; n++) {
319 if (ep->ref[n] == NULL)
320 break;
321 if (ep->ref[n] != ref)
322 continue;
323 TSRELEASE("GEOM events");
324 TAILQ_REMOVE(&g_events, ep, events);
325 ep->func(ep->arg, EV_CANCEL);
326 mtx_assert(&g_eventlock, MA_OWNED);
327 if (ep->flag & EV_WAKEUP) {
328 ep->flag |= (EV_DONE|EV_CANCELED);
329 wakeup(ep);
330 } else {
331 g_free(ep);
332 }
333 break;
334 }
335 }
336 if (TAILQ_EMPTY(&g_events))
337 wakeup(&g_pending_events);
338 mtx_unlock(&g_eventlock);
339 }
340
341 struct g_event *
342 g_alloc_event(int flag)
343 {
344 KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
345 ("Wrong flag to g_alloc_event"));
346
347 return (g_malloc(sizeof(struct g_event), flag | M_ZERO));
348 }
349
350 static void
351 g_post_event_ep_va(g_event_t *func, void *arg, int wuflag,
352 struct g_event *ep, va_list ap)
353 {
354 void *p;
355 u_int n;
356
357 ep->flag = wuflag;
358 for (n = 0; n < G_N_EVENTREFS; n++) {
359 p = va_arg(ap, void *);
360 if (p == NULL)
361 break;
362 g_trace(G_T_TOPOLOGY, " ref %p", p);
363 ep->ref[n] = p;
364 }
365 KASSERT(p == NULL, ("Too many references to event"));
366 ep->func = func;
367 ep->arg = arg;
368 mtx_lock(&g_eventlock);
369 TSHOLD("GEOM events");
370 TAILQ_INSERT_TAIL(&g_events, ep, events);
371 mtx_unlock(&g_eventlock);
372 wakeup(&g_wait_event);
373 curthread->td_pflags |= TDP_GEOM;
374 ast_sched(curthread, TDA_GEOM);
375 }
376
377 void
378 g_post_event_ep(g_event_t *func, void *arg, struct g_event *ep, ...)
379 {
380 va_list ap;
381
382 va_start(ap, ep);
383 g_post_event_ep_va(func, arg, 0, ep, ap);
384 va_end(ap);
385 }
386
387
388 static int
389 g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
390 {
391 struct g_event *ep;
392
393 g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
394 func, arg, flag, wuflag);
395 KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
396 ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
397 ep = g_alloc_event(flag);
398 if (ep == NULL)
399 return (ENOMEM);
400 if (epp != NULL)
401 *epp = ep;
402 g_post_event_ep_va(func, arg, wuflag, ep, ap);
403 return (0);
404 }
405
406 int
407 g_post_event(g_event_t *func, void *arg, int flag, ...)
408 {
409 va_list ap;
410 int i;
411
412 KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
413 ("Wrong flag to g_post_event"));
414 va_start(ap, flag);
415 i = g_post_event_x(func, arg, flag, 0, NULL, ap);
416 va_end(ap);
417 return (i);
418 }
419
420 void
421 g_do_wither(void)
422 {
423
424 mtx_lock(&g_eventlock);
425 g_wither_work = 1;
426 mtx_unlock(&g_eventlock);
427 wakeup(&g_wait_event);
428 }
429
430 /*
431 * XXX: It might actually be useful to call this function with topology held.
432 * XXX: This would ensure that the event gets created before anything else
433 * XXX: changes. At present all users have a handle on things in some other
434 * XXX: way, so this remains an XXX for now.
435 */
436
437 int
438 g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
439 {
440 va_list ap;
441 struct g_event *ep;
442 int error;
443
444 g_topology_assert_not();
445 KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
446 ("Wrong flag to g_post_event"));
447 va_start(ap, flag);
448 error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
449 va_end(ap);
450 if (error)
451 return (error);
452
453 mtx_lock(&g_eventlock);
454 while (!(ep->flag & EV_DONE))
455 msleep(ep, &g_eventlock, PRIBIO, "g_waitfor_event", 0);
456 if (ep->flag & EV_CANCELED)
457 error = EAGAIN;
458 mtx_unlock(&g_eventlock);
459
460 g_free(ep);
461 return (error);
462 }
463
464 void
465 g_event_init(void)
466 {
467
468 mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
469 }
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