geom_event.c revision 226985 
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: head/sys/geom/geom_event.c 226985 2011-11-01 08:57:49Z 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
58TAILQ_HEAD(event_tailq_head, g_event);
59
60static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
61static u_int g_pending_events;
62static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
63static struct mtx g_eventlock;
64static int g_wither_work;
65
66#define G_N_EVENTREFS		20
67
68struct 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
81void
82g_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
97void
98g_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
113struct g_attrchanged_args {
114	struct g_provider *pp;
115	const char *attr;
116};
117
118static void
119g_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
143int
144g_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
160void
161g_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
186static void
187g_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	cp = LIST_FIRST(&pp->consumers);
206	while (cp != NULL) {
207		cp2 = LIST_NEXT(cp, consumers);
208		KASSERT(cp->geom->orphan != NULL,
209		    ("geom %s has no orphan, class %s",
210		    cp->geom->name, cp->geom->class->name));
211		cp->geom->orphan(cp);
212		cp = cp2;
213	}
214	if (LIST_EMPTY(&pp->consumers) && wf)
215		g_destroy_provider(pp);
216	else
217		pp->flags |= wf;
218#ifdef notyet
219	cp = LIST_FIRST(&pp->consumers);
220	if (cp != NULL)
221		return;
222	if (pp->geom->flags & G_GEOM_WITHER)
223		g_destroy_provider(pp);
224#endif
225}
226
227static int
228one_event(void)
229{
230	struct g_event *ep;
231	struct g_provider *pp;
232
233	g_topology_assert();
234	mtx_lock(&g_eventlock);
235	TAILQ_FOREACH(pp, &g_doorstep, orphan) {
236		if (pp->nstart == pp->nend)
237			break;
238	}
239	if (pp != NULL) {
240		G_VALID_PROVIDER(pp);
241		TAILQ_REMOVE(&g_doorstep, pp, orphan);
242		mtx_unlock(&g_eventlock);
243		g_orphan_register(pp);
244		return (1);
245	}
246
247	ep = TAILQ_FIRST(&g_events);
248	if (ep == NULL) {
249		wakeup(&g_pending_events);
250		return (0);
251	}
252	if (ep->flag & EV_INPROGRESS) {
253		mtx_unlock(&g_eventlock);
254		return (1);
255	}
256	ep->flag |= EV_INPROGRESS;
257	mtx_unlock(&g_eventlock);
258	g_topology_assert();
259	ep->func(ep->arg, 0);
260	g_topology_assert();
261	mtx_lock(&g_eventlock);
262	TAILQ_REMOVE(&g_events, ep, events);
263	ep->flag &= ~EV_INPROGRESS;
264	if (ep->flag & EV_WAKEUP) {
265		ep->flag |= EV_DONE;
266		mtx_unlock(&g_eventlock);
267		wakeup(ep);
268	} else {
269		mtx_unlock(&g_eventlock);
270		g_free(ep);
271	}
272	return (1);
273}
274
275void
276g_run_events()
277{
278	int i;
279
280	for (;;) {
281		g_topology_lock();
282		while (one_event())
283			;
284		mtx_assert(&g_eventlock, MA_OWNED);
285		i = g_wither_work;
286		if (i) {
287			mtx_unlock(&g_eventlock);
288			while (i) {
289				i = g_wither_washer();
290				g_wither_work = i & 1;
291				i &= 2;
292			}
293			g_topology_unlock();
294		} else {
295			g_topology_unlock();
296			msleep(&g_wait_event, &g_eventlock, PRIBIO | PDROP,
297			    "-", TAILQ_EMPTY(&g_doorstep) ? 0 : hz / 10);
298		}
299	}
300	/* NOTREACHED */
301}
302
303void
304g_cancel_event(void *ref)
305{
306	struct g_event *ep, *epn;
307	struct g_provider *pp;
308	u_int n;
309
310	mtx_lock(&g_eventlock);
311	TAILQ_FOREACH(pp, &g_doorstep, orphan) {
312		if (pp != ref)
313			continue;
314		TAILQ_REMOVE(&g_doorstep, pp, orphan);
315		break;
316	}
317	TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
318		if (ep->flag & EV_INPROGRESS)
319			continue;
320		for (n = 0; n < G_N_EVENTREFS; n++) {
321			if (ep->ref[n] == NULL)
322				break;
323			if (ep->ref[n] != ref)
324				continue;
325			TAILQ_REMOVE(&g_events, ep, events);
326			ep->func(ep->arg, EV_CANCEL);
327			mtx_assert(&g_eventlock, MA_OWNED);
328			if (ep->flag & EV_WAKEUP) {
329				ep->flag |= (EV_DONE|EV_CANCELED);
330				wakeup(ep);
331			} else {
332				g_free(ep);
333			}
334			break;
335		}
336	}
337	if (TAILQ_EMPTY(&g_events))
338		wakeup(&g_pending_events);
339	mtx_unlock(&g_eventlock);
340}
341
342static int
343g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
344{
345	struct g_event *ep;
346	void *p;
347	u_int n;
348
349	g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
350	    func, arg, flag, wuflag);
351	KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
352	    ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
353	ep = g_malloc(sizeof *ep, flag | M_ZERO);
354	if (ep == NULL)
355		return (ENOMEM);
356	ep->flag = wuflag;
357	for (n = 0; n < G_N_EVENTREFS; n++) {
358		p = va_arg(ap, void *);
359		if (p == NULL)
360			break;
361		g_trace(G_T_TOPOLOGY, "  ref %p", p);
362		ep->ref[n] = p;
363	}
364	KASSERT(p == NULL, ("Too many references to event"));
365	ep->func = func;
366	ep->arg = arg;
367	mtx_lock(&g_eventlock);
368	TAILQ_INSERT_TAIL(&g_events, ep, events);
369	mtx_unlock(&g_eventlock);
370	wakeup(&g_wait_event);
371	if (epp != NULL)
372		*epp = ep;
373	curthread->td_pflags |= TDP_GEOM;
374	return (0);
375}
376
377int
378g_post_event(g_event_t *func, void *arg, int flag, ...)
379{
380	va_list ap;
381	int i;
382
383	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
384	    ("Wrong flag to g_post_event"));
385	va_start(ap, flag);
386	i = g_post_event_x(func, arg, flag, 0, NULL, ap);
387	va_end(ap);
388	return (i);
389}
390
391void
392g_do_wither()
393{
394
395	mtx_lock(&g_eventlock);
396	g_wither_work = 1;
397	mtx_unlock(&g_eventlock);
398	wakeup(&g_wait_event);
399}
400
401/*
402 * XXX: It might actually be useful to call this function with topology held.
403 * XXX: This would ensure that the event gets created before anything else
404 * XXX: changes.  At present all users have a handle on things in some other
405 * XXX: way, so this remains an XXX for now.
406 */
407
408int
409g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
410{
411	va_list ap;
412	struct g_event *ep;
413	int error;
414
415	g_topology_assert_not();
416	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
417	    ("Wrong flag to g_post_event"));
418	va_start(ap, flag);
419	error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
420	va_end(ap);
421	if (error)
422		return (error);
423
424	mtx_lock(&g_eventlock);
425	while (!(ep->flag & EV_DONE))
426		msleep(ep, &g_eventlock, PRIBIO, "g_waitfor_event", hz);
427	if (ep->flag & EV_CANCELED)
428		error = EAGAIN;
429	mtx_unlock(&g_eventlock);
430
431	g_free(ep);
432	return (error);
433}
434
435void
436g_event_init()
437{
438
439	mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
440}
441