xref: /freebsd/sys/geom/geom_event.c (revision b1f9167f94059fd55c630891d359bcff987bd7eb)
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("$FreeBSD$");
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 struct g_attrchanged_args {
114 	struct g_provider *pp;
115 	const char *attr;
116 };
117 
118 static void
119 g_attr_changed_event(void *arg, int flag)
120 {
121 	struct g_attrchanged_args *args;
122 	struct g_provider *pp;
123 	struct g_consumer *cp;
124 	struct g_consumer *next_cp;
125 
126 	args = arg;
127 	pp = args->pp;
128 
129 	g_topology_assert();
130 	if (flag != EV_CANCEL && g_shutdown == 0) {
131 
132 		/*
133 		 * Tell all consumers of the change.
134 		 */
135 		LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, next_cp) {
136 			if (cp->geom->attrchanged != NULL)
137 				cp->geom->attrchanged(cp, args->attr);
138 		}
139 	}
140 	g_free(args);
141 }
142 
143 int
144 g_attr_changed(struct g_provider *pp, const char *attr, int flag)
145 {
146 	struct g_attrchanged_args *args;
147 	int error;
148 
149 	args = g_malloc(sizeof *args, flag);
150 	if (args == NULL)
151 		return (ENOMEM);
152 	args->pp = pp;
153 	args->attr = attr;
154 	error = g_post_event(g_attr_changed_event, args, flag, pp, NULL);
155 	if (error != 0)
156 		g_free(args);
157 	return (error);
158 }
159 
160 void
161 g_orphan_provider(struct g_provider *pp, int error)
162 {
163 
164 	/* G_VALID_PROVIDER(pp)  We likely lack topology lock */
165 	g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
166 	    pp, pp->name, error);
167 	KASSERT(error != 0,
168 	    ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
169 	     pp, pp->name));
170 
171 	pp->error = error;
172 	mtx_lock(&g_eventlock);
173 	KASSERT(!(pp->flags & G_PF_ORPHAN),
174 	    ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
175 	pp->flags |= G_PF_ORPHAN;
176 	TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
177 	mtx_unlock(&g_eventlock);
178 	wakeup(&g_wait_event);
179 }
180 
181 /*
182  * This function is called once on each provider which the event handler
183  * finds on its g_doorstep.
184  */
185 
186 static void
187 g_orphan_register(struct g_provider *pp)
188 {
189 	struct g_consumer *cp, *cp2;
190 	int wf;
191 
192 	g_topology_assert();
193 	G_VALID_PROVIDER(pp);
194 	g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
195 
196 	g_cancel_event(pp);
197 
198 	wf = pp->flags & G_PF_WITHER;
199 	pp->flags &= ~G_PF_WITHER;
200 
201 	/*
202 	 * Tell all consumers the bad news.
203 	 * Don't be surprised if they self-destruct.
204 	 */
205 	LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, cp2) {
206 		KASSERT(cp->geom->orphan != NULL,
207 		    ("geom %s has no orphan, class %s",
208 		    cp->geom->name, cp->geom->class->name));
209 		/*
210 		 * XXX: g_dev_orphan method does deferred destroying
211 		 * and it is possible, that other event could already
212 		 * call the orphan method. Check consumer's flags to
213 		 * do not schedule it twice.
214 		 */
215 		if (cp->flags & G_CF_ORPHAN)
216 			continue;
217 		cp->flags |= G_CF_ORPHAN;
218 		cp->geom->orphan(cp);
219 	}
220 	if (LIST_EMPTY(&pp->consumers) && wf)
221 		g_destroy_provider(pp);
222 	else
223 		pp->flags |= wf;
224 #ifdef notyet
225 	cp = LIST_FIRST(&pp->consumers);
226 	if (cp != NULL)
227 		return;
228 	if (pp->geom->flags & G_GEOM_WITHER)
229 		g_destroy_provider(pp);
230 #endif
231 }
232 
233 static int
234 one_event(void)
235 {
236 	struct g_event *ep;
237 	struct g_provider *pp;
238 
239 	g_topology_assert();
240 	mtx_lock(&g_eventlock);
241 	TAILQ_FOREACH(pp, &g_doorstep, orphan) {
242 		if (pp->nstart == pp->nend)
243 			break;
244 	}
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 	if (ep->flag & EV_INPROGRESS) {
259 		mtx_unlock(&g_eventlock);
260 		return (1);
261 	}
262 	ep->flag |= EV_INPROGRESS;
263 	mtx_unlock(&g_eventlock);
264 	g_topology_assert();
265 	ep->func(ep->arg, 0);
266 	g_topology_assert();
267 	mtx_lock(&g_eventlock);
268 	TAILQ_REMOVE(&g_events, ep, events);
269 	ep->flag &= ~EV_INPROGRESS;
270 	if (ep->flag & EV_WAKEUP) {
271 		ep->flag |= EV_DONE;
272 		mtx_unlock(&g_eventlock);
273 		wakeup(ep);
274 	} else {
275 		mtx_unlock(&g_eventlock);
276 		g_free(ep);
277 	}
278 	return (1);
279 }
280 
281 void
282 g_run_events()
283 {
284 
285 	for (;;) {
286 		g_topology_lock();
287 		while (one_event())
288 			;
289 		mtx_assert(&g_eventlock, MA_OWNED);
290 		if (g_wither_work) {
291 			g_wither_work = 0;
292 			mtx_unlock(&g_eventlock);
293 			g_wither_washer();
294 			g_topology_unlock();
295 		} else {
296 			g_topology_unlock();
297 			msleep(&g_wait_event, &g_eventlock, PRIBIO | PDROP,
298 			    "-", TAILQ_EMPTY(&g_doorstep) ? 0 : hz / 10);
299 		}
300 	}
301 	/* NOTREACHED */
302 }
303 
304 void
305 g_cancel_event(void *ref)
306 {
307 	struct g_event *ep, *epn;
308 	struct g_provider *pp;
309 	u_int n;
310 
311 	mtx_lock(&g_eventlock);
312 	TAILQ_FOREACH(pp, &g_doorstep, orphan) {
313 		if (pp != ref)
314 			continue;
315 		TAILQ_REMOVE(&g_doorstep, pp, orphan);
316 		break;
317 	}
318 	TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
319 		if (ep->flag & EV_INPROGRESS)
320 			continue;
321 		for (n = 0; n < G_N_EVENTREFS; n++) {
322 			if (ep->ref[n] == NULL)
323 				break;
324 			if (ep->ref[n] != ref)
325 				continue;
326 			TAILQ_REMOVE(&g_events, ep, events);
327 			ep->func(ep->arg, EV_CANCEL);
328 			mtx_assert(&g_eventlock, MA_OWNED);
329 			if (ep->flag & EV_WAKEUP) {
330 				ep->flag |= (EV_DONE|EV_CANCELED);
331 				wakeup(ep);
332 			} else {
333 				g_free(ep);
334 			}
335 			break;
336 		}
337 	}
338 	if (TAILQ_EMPTY(&g_events))
339 		wakeup(&g_pending_events);
340 	mtx_unlock(&g_eventlock);
341 }
342 
343 static int
344 g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
345 {
346 	struct g_event *ep;
347 	void *p;
348 	u_int n;
349 
350 	g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
351 	    func, arg, flag, wuflag);
352 	KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
353 	    ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
354 	ep = g_malloc(sizeof *ep, flag | M_ZERO);
355 	if (ep == NULL)
356 		return (ENOMEM);
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 	TAILQ_INSERT_TAIL(&g_events, ep, events);
370 	mtx_unlock(&g_eventlock);
371 	wakeup(&g_wait_event);
372 	if (epp != NULL)
373 		*epp = ep;
374 	curthread->td_pflags |= TDP_GEOM;
375 	return (0);
376 }
377 
378 int
379 g_post_event(g_event_t *func, void *arg, int flag, ...)
380 {
381 	va_list ap;
382 	int i;
383 
384 	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
385 	    ("Wrong flag to g_post_event"));
386 	va_start(ap, flag);
387 	i = g_post_event_x(func, arg, flag, 0, NULL, ap);
388 	va_end(ap);
389 	return (i);
390 }
391 
392 void
393 g_do_wither()
394 {
395 
396 	mtx_lock(&g_eventlock);
397 	g_wither_work = 1;
398 	mtx_unlock(&g_eventlock);
399 	wakeup(&g_wait_event);
400 }
401 
402 /*
403  * XXX: It might actually be useful to call this function with topology held.
404  * XXX: This would ensure that the event gets created before anything else
405  * XXX: changes.  At present all users have a handle on things in some other
406  * XXX: way, so this remains an XXX for now.
407  */
408 
409 int
410 g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
411 {
412 	va_list ap;
413 	struct g_event *ep;
414 	int error;
415 
416 	g_topology_assert_not();
417 	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
418 	    ("Wrong flag to g_post_event"));
419 	va_start(ap, flag);
420 	error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
421 	va_end(ap);
422 	if (error)
423 		return (error);
424 
425 	mtx_lock(&g_eventlock);
426 	while (!(ep->flag & EV_DONE))
427 		msleep(ep, &g_eventlock, PRIBIO, "g_waitfor_event", hz);
428 	if (ep->flag & EV_CANCELED)
429 		error = EAGAIN;
430 	mtx_unlock(&g_eventlock);
431 
432 	g_free(ep);
433 	return (error);
434 }
435 
436 void
437 g_event_init()
438 {
439 
440 	mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
441 }
442