geom_event.c revision 125318 
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 125318 2004-02-02 10:58:07Z phk $");
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 <machine/stdarg.h>
51#include <sys/errno.h>
52#include <sys/time.h>
53#include <geom/geom.h>
54#include <geom/geom_int.h>
55
56TAILQ_HEAD(event_tailq_head, g_event);
57
58static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
59static u_int g_pending_events;
60static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
61static struct mtx g_eventlock;
62static struct sx g_eventstall;
63
64#define G_N_EVENTREFS		20
65
66struct g_event {
67	TAILQ_ENTRY(g_event)	events;
68	g_event_t		*func;
69	void			*arg;
70	int			flag;
71	void			*ref[G_N_EVENTREFS];
72};
73
74#define EV_DONE		0x80000
75#define EV_WAKEUP	0x40000
76#define EV_CANCELED	0x20000
77
78void
79g_waitidle(void)
80{
81
82	while (g_pending_events)
83		tsleep(&g_pending_events, PPAUSE, "g_waitidle", hz/5);
84}
85
86void
87g_stall_events(void)
88{
89
90	sx_xlock(&g_eventstall);
91}
92
93void
94g_release_events(void)
95{
96
97	sx_xunlock(&g_eventstall);
98}
99
100void
101g_orphan_provider(struct g_provider *pp, int error)
102{
103
104	g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
105	    pp, pp->name, error);
106	KASSERT(error != 0,
107	    ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
108	     pp, pp->name));
109
110	pp->error = error;
111	mtx_lock(&g_eventlock);
112	KASSERT(!(pp->flags & G_PF_ORPHAN),
113	    ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
114	pp->flags |= G_PF_ORPHAN;
115	TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
116	mtx_unlock(&g_eventlock);
117	wakeup(&g_wait_event);
118}
119
120/*
121 * This function is called once on each provider which the event handler
122 * finds on its g_doorstep.
123 */
124
125static void
126g_orphan_register(struct g_provider *pp)
127{
128	struct g_consumer *cp, *cp2;
129	int wf;
130
131	g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
132	g_topology_assert();
133
134	wf = pp->flags & G_PF_WITHER;
135	pp->flags &= ~G_PF_WITHER;
136
137	/*
138	 * Tell all consumers the bad news.
139	 * Don't be surprised if they self-destruct.
140	 */
141	cp = LIST_FIRST(&pp->consumers);
142	while (cp != NULL) {
143		cp2 = LIST_NEXT(cp, consumers);
144		KASSERT(cp->geom->orphan != NULL,
145		    ("geom %s has no orphan, class %s",
146		    cp->geom->name, cp->geom->class->name));
147		cp->geom->orphan(cp);
148		cp = cp2;
149	}
150	if (LIST_EMPTY(&pp->consumers) && wf)
151		g_destroy_provider(pp);
152	else
153		pp->flags |= wf;
154#ifdef notyet
155	cp = LIST_FIRST(&pp->consumers);
156	if (cp != NULL)
157		return;
158	if (pp->geom->flags & G_GEOM_WITHER)
159		g_destroy_provider(pp);
160#endif
161}
162
163static int
164one_event(void)
165{
166	struct g_event *ep;
167	struct g_provider *pp;
168
169	sx_xlock(&g_eventstall);
170	g_topology_lock();
171	for (;;) {
172		mtx_lock(&g_eventlock);
173		pp = TAILQ_FIRST(&g_doorstep);
174		if (pp != NULL)
175			TAILQ_REMOVE(&g_doorstep, pp, orphan);
176		mtx_unlock(&g_eventlock);
177		if (pp == NULL)
178			break;
179		g_orphan_register(pp);
180	}
181	mtx_lock(&g_eventlock);
182	ep = TAILQ_FIRST(&g_events);
183	if (ep == NULL) {
184		mtx_unlock(&g_eventlock);
185		g_topology_unlock();
186		sx_xunlock(&g_eventstall);
187		return (0);
188	}
189	TAILQ_REMOVE(&g_events, ep, events);
190	mtx_unlock(&g_eventlock);
191	g_topology_assert();
192	ep->func(ep->arg, 0);
193	g_topology_assert();
194	if (ep->flag & EV_WAKEUP) {
195		ep->flag |= EV_DONE;
196		wakeup(ep);
197	} else {
198		g_free(ep);
199	}
200	g_pending_events--;
201	if (g_pending_events == 0)
202		wakeup(&g_pending_events);
203	g_topology_unlock();
204	sx_xunlock(&g_eventstall);
205	return (1);
206}
207
208void
209g_run_events()
210{
211
212	while (one_event())
213		;
214}
215
216void
217g_cancel_event(void *ref)
218{
219	struct g_event *ep, *epn;
220	struct g_provider *pp;
221	u_int n;
222
223	mtx_lock(&g_eventlock);
224	TAILQ_FOREACH(pp, &g_doorstep, orphan) {
225		if (pp != ref)
226			continue;
227		TAILQ_REMOVE(&g_doorstep, pp, orphan);
228		break;
229	}
230	for (ep = TAILQ_FIRST(&g_events); ep != NULL; ep = epn) {
231		epn = TAILQ_NEXT(ep, events);
232		for (n = 0; n < G_N_EVENTREFS; n++) {
233			if (ep->ref[n] == NULL)
234				break;
235			if (ep->ref[n] == ref) {
236				TAILQ_REMOVE(&g_events, ep, events);
237				ep->func(ep->arg, EV_CANCEL);
238				if (ep->flag & EV_WAKEUP) {
239					ep->flag |= EV_DONE;
240					ep->flag |= EV_CANCELED;
241					wakeup(ep);
242				} else {
243					g_free(ep);
244				}
245				if (--g_pending_events == 0)
246					wakeup(&g_pending_events);
247				break;
248			}
249		}
250	}
251	mtx_unlock(&g_eventlock);
252}
253
254static int
255g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
256{
257	struct g_event *ep;
258	void *p;
259	u_int n;
260
261	g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
262	    func, arg, flag, wakeup);
263	KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
264	    ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
265	ep = g_malloc(sizeof *ep, flag | M_ZERO);
266	if (ep == NULL)
267		return (ENOMEM);
268	ep->flag = wuflag;
269	for (n = 0; n < G_N_EVENTREFS; n++) {
270		p = va_arg(ap, void *);
271		if (p == NULL)
272			break;
273		g_trace(G_T_TOPOLOGY, "  ref %p", p);
274		ep->ref[n] = p;
275	}
276	KASSERT(p == NULL, ("Too many references to event"));
277	ep->func = func;
278	ep->arg = arg;
279	mtx_lock(&g_eventlock);
280	g_pending_events++;
281	TAILQ_INSERT_TAIL(&g_events, ep, events);
282	mtx_unlock(&g_eventlock);
283	wakeup(&g_wait_event);
284	if (epp != NULL)
285		*epp = ep;
286	return (0);
287}
288
289int
290g_post_event(g_event_t *func, void *arg, int flag, ...)
291{
292	va_list ap;
293	int i;
294
295	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
296	    ("Wrong flag to g_post_event"));
297	va_start(ap, flag);
298	i = g_post_event_x(func, arg, flag, 0, NULL, ap);
299	va_end(ap);
300	return (i);
301}
302
303
304/*
305 * XXX: It might actually be useful to call this function with topology held.
306 * XXX: This would ensure that the event gets created before anything else
307 * XXX: changes.  At present all users have a handle on things in some other
308 * XXX: way, so this remains an XXX for now.
309 */
310
311int
312g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
313{
314	va_list ap;
315	struct g_event *ep;
316	int error;
317
318	/* g_topology_assert_not(); */
319	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
320	    ("Wrong flag to g_post_event"));
321	va_start(ap, flag);
322	error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
323	va_end(ap);
324	if (error)
325		return (error);
326	do
327		tsleep(ep, PRIBIO, "g_waitfor_event", hz);
328	while (!(ep->flag & EV_DONE));
329	if (ep->flag & EV_CANCELED)
330		error = EAGAIN;
331	g_free(ep);
332	return (error);
333}
334
335void
336g_event_init()
337{
338
339	mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
340	sx_init(&g_eventstall, "GEOM event stalling");
341}
342