geom_event.c revision 113937 
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 * $FreeBSD: head/sys/geom/geom_event.c 113937 2003-04-23 20:46:12Z phk $
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/param.h>
44#include <sys/malloc.h>
45#include <sys/systm.h>
46#include <sys/kernel.h>
47#include <sys/lock.h>
48#include <sys/mutex.h>
49#include <machine/stdarg.h>
50#include <sys/errno.h>
51#include <sys/time.h>
52#include <geom/geom.h>
53#include <geom/geom_int.h>
54
55static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
56static u_int g_pending_events;
57static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
58static struct mtx g_eventlock;
59static struct sx g_eventstall;
60
61void
62g_waitidle(void)
63{
64
65	while (g_pending_events)
66		tsleep(&g_pending_events, PPAUSE, "g_waitidle", hz/5);
67}
68
69void
70g_stall_events(void)
71{
72
73	sx_xlock(&g_eventstall);
74}
75
76void
77g_release_events(void)
78{
79
80	sx_xunlock(&g_eventstall);
81}
82
83void
84g_orphan_provider(struct g_provider *pp, int error)
85{
86
87	g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
88	    pp, pp->name, error);
89	KASSERT(error != 0,
90	    ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
91	     pp, pp->name));
92	pp->error = error;
93	mtx_lock(&g_eventlock);
94	TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
95	mtx_unlock(&g_eventlock);
96	wakeup(&g_wait_event);
97}
98
99/*
100 * This function is called once on each provider which the event handler
101 * finds on its g_doorstep.
102 */
103
104static void
105g_orphan_register(struct g_provider *pp)
106{
107	struct g_consumer *cp, *cp2;
108
109	g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
110	g_topology_assert();
111
112	/*
113	 * Tell all consumers the bad news.
114	 * Don't be surprised if they self-destruct.
115	 */
116	cp = LIST_FIRST(&pp->consumers);
117	while (cp != NULL) {
118		cp2 = LIST_NEXT(cp, consumers);
119		KASSERT(cp->geom->orphan != NULL,
120		    ("geom %s has no orphan, class %s",
121		    cp->geom->name, cp->geom->class->name));
122		cp->geom->orphan(cp);
123		cp = cp2;
124	}
125#ifdef notyet
126	cp = LIST_FIRST(&pp->consumers);
127	if (cp != NULL)
128		return;
129	if (pp->geom->flags & G_GEOM_WITHER)
130		g_destroy_provider(pp);
131#endif
132}
133
134static void
135g_destroy_event(struct g_event *ep)
136{
137
138	g_free(ep);
139}
140
141static int
142one_event(void)
143{
144	struct g_event *ep;
145	struct g_provider *pp;
146
147	sx_xlock(&g_eventstall);
148	g_topology_lock();
149	for (;;) {
150		mtx_lock(&g_eventlock);
151		pp = TAILQ_FIRST(&g_doorstep);
152		if (pp != NULL)
153			TAILQ_REMOVE(&g_doorstep, pp, orphan);
154		mtx_unlock(&g_eventlock);
155		if (pp == NULL)
156			break;
157		g_orphan_register(pp);
158	}
159	mtx_lock(&g_eventlock);
160	ep = TAILQ_FIRST(&g_events);
161	if (ep == NULL) {
162		mtx_unlock(&g_eventlock);
163		g_topology_unlock();
164		sx_xunlock(&g_eventstall);
165		return (0);
166	}
167	TAILQ_REMOVE(&g_events, ep, events);
168	mtx_unlock(&g_eventlock);
169	g_topology_assert();
170	ep->func(ep->arg, 0);
171	g_topology_assert();
172	g_destroy_event(ep);
173	g_pending_events--;
174	if (g_pending_events == 0)
175		wakeup(&g_pending_events);
176	g_topology_unlock();
177	sx_xunlock(&g_eventstall);
178	return (1);
179}
180
181void
182g_run_events()
183{
184
185	while (one_event())
186		;
187}
188
189void
190g_cancel_event(void *ref)
191{
192	struct g_event *ep, *epn;
193	u_int n;
194
195	mtx_lock(&g_eventlock);
196	for (ep = TAILQ_FIRST(&g_events); ep != NULL; ep = epn) {
197		epn = TAILQ_NEXT(ep, events);
198		for (n = 0; n < G_N_EVENTREFS; n++) {
199			if (ep->ref[n] == NULL)
200				break;
201			if (ep->ref[n] == ref) {
202				TAILQ_REMOVE(&g_events, ep, events);
203				ep->func(ep->arg, EV_CANCEL);
204				g_free(ep);
205				break;
206			}
207		}
208	}
209	mtx_unlock(&g_eventlock);
210}
211
212int
213g_post_event(g_event_t *func, void *arg, int flag, ...)
214{
215	struct g_event *ep;
216	va_list ap;
217	void *p;
218	u_int n;
219
220	g_trace(G_T_TOPOLOGY, "g_post_event(%p, %p, %d", func, arg, flag);
221	KASSERT(flag == M_NOWAIT || flag == M_WAITOK,
222	    ("Wrong flag to g_post_event"));
223	ep = g_malloc(sizeof *ep, flag | M_ZERO);
224	if (ep == NULL)
225		return (ENOMEM);
226	va_start(ap, flag);
227	for (n = 0; n < G_N_EVENTREFS; n++) {
228		p = va_arg(ap, void *);
229		if (p == NULL)
230			break;
231		g_trace(G_T_TOPOLOGY, "  ref %p", p);
232		ep->ref[n++] = p;
233	}
234	va_end(ap);
235	KASSERT(p == NULL, ("Too many references to event"));
236	ep->func = func;
237	ep->arg = arg;
238	mtx_lock(&g_eventlock);
239	g_pending_events++;
240	TAILQ_INSERT_TAIL(&g_events, ep, events);
241	mtx_unlock(&g_eventlock);
242	wakeup(&g_wait_event);
243	return (0);
244}
245
246
247void
248g_event_init()
249{
250
251	mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
252	sx_init(&g_eventstall, "GEOM event stalling");
253}
254