geom_event.c revision 136837 
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 136837 2004-10-23 20:49:17Z 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 <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
80void
81g_waitidle(void)
82{
83
84	g_topology_assert_not();
85	mtx_assert(&Giant, MA_NOTOWNED);
86
87	while (g_pending_events)
88		tsleep(&g_pending_events, PPAUSE, "g_waitidle", hz/5);
89	curthread->td_pflags &= ~TDP_GEOM;
90}
91
92void
93g_orphan_provider(struct g_provider *pp, int error)
94{
95
96	/* G_VALID_PROVIDER(pp)  We likely lack topology lock */
97	g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
98	    pp, pp->name, error);
99	KASSERT(error != 0,
100	    ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
101	     pp, pp->name));
102
103	pp->error = error;
104	mtx_lock(&g_eventlock);
105	KASSERT(!(pp->flags & G_PF_ORPHAN),
106	    ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
107	pp->flags |= G_PF_ORPHAN;
108	TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
109	mtx_unlock(&g_eventlock);
110	wakeup(&g_wait_event);
111}
112
113/*
114 * This function is called once on each provider which the event handler
115 * finds on its g_doorstep.
116 */
117
118static void
119g_orphan_register(struct g_provider *pp)
120{
121	struct g_consumer *cp, *cp2;
122	int wf;
123
124	g_topology_assert();
125	G_VALID_PROVIDER(pp);
126	g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
127
128	wf = pp->flags & G_PF_WITHER;
129	pp->flags &= ~G_PF_WITHER;
130
131	/*
132	 * Tell all consumers the bad news.
133	 * Don't be surprised if they self-destruct.
134	 */
135	cp = LIST_FIRST(&pp->consumers);
136	while (cp != NULL) {
137		cp2 = LIST_NEXT(cp, consumers);
138		KASSERT(cp->geom->orphan != NULL,
139		    ("geom %s has no orphan, class %s",
140		    cp->geom->name, cp->geom->class->name));
141		cp->geom->orphan(cp);
142		cp = cp2;
143	}
144	if (LIST_EMPTY(&pp->consumers) && wf)
145		g_destroy_provider(pp);
146	else
147		pp->flags |= wf;
148#ifdef notyet
149	cp = LIST_FIRST(&pp->consumers);
150	if (cp != NULL)
151		return;
152	if (pp->geom->flags & G_GEOM_WITHER)
153		g_destroy_provider(pp);
154#endif
155}
156
157static int
158one_event(void)
159{
160	struct g_event *ep;
161	struct g_provider *pp;
162
163	g_topology_lock();
164	for (;;) {
165		mtx_lock(&g_eventlock);
166		pp = TAILQ_FIRST(&g_doorstep);
167		if (pp != NULL) {
168			G_VALID_PROVIDER(pp);
169			TAILQ_REMOVE(&g_doorstep, pp, orphan);
170		}
171		mtx_unlock(&g_eventlock);
172		if (pp == NULL)
173			break;
174		g_orphan_register(pp);
175	}
176	mtx_lock(&g_eventlock);
177	ep = TAILQ_FIRST(&g_events);
178	if (ep == NULL) {
179		mtx_unlock(&g_eventlock);
180		g_topology_unlock();
181		return (0);
182	}
183	TAILQ_REMOVE(&g_events, ep, events);
184	mtx_unlock(&g_eventlock);
185	g_topology_assert();
186	ep->func(ep->arg, 0);
187	g_topology_assert();
188	if (ep->flag & EV_WAKEUP) {
189		ep->flag |= EV_DONE;
190		wakeup(ep);
191	} else {
192		g_free(ep);
193	}
194	g_pending_events--;
195	if (g_pending_events == 0)
196		wakeup(&g_pending_events);
197	g_topology_unlock();
198	return (1);
199}
200
201void
202g_run_events()
203{
204	int i;
205
206	while (one_event())
207		;
208	g_topology_lock();
209	i = g_wither_work;
210	while (i) {
211		i = g_wither_washer();
212		g_wither_work = i & 1;
213		i &= 2;
214	}
215	g_topology_unlock();
216}
217
218void
219g_cancel_event(void *ref)
220{
221	struct g_event *ep, *epn;
222	struct g_provider *pp;
223	u_int n;
224
225	mtx_lock(&g_eventlock);
226	TAILQ_FOREACH(pp, &g_doorstep, orphan) {
227		if (pp != ref)
228			continue;
229		TAILQ_REMOVE(&g_doorstep, pp, orphan);
230		break;
231	}
232	for (ep = TAILQ_FIRST(&g_events); ep != NULL; ep = epn) {
233		epn = TAILQ_NEXT(ep, events);
234		for (n = 0; n < G_N_EVENTREFS; n++) {
235			if (ep->ref[n] == NULL)
236				break;
237			if (ep->ref[n] == ref) {
238				TAILQ_REMOVE(&g_events, ep, events);
239				ep->func(ep->arg, EV_CANCEL);
240				if (ep->flag & EV_WAKEUP) {
241					ep->flag |= EV_DONE;
242					ep->flag |= EV_CANCELED;
243					wakeup(ep);
244				} else {
245					g_free(ep);
246				}
247				if (--g_pending_events == 0)
248					wakeup(&g_pending_events);
249				break;
250			}
251		}
252	}
253	mtx_unlock(&g_eventlock);
254}
255
256static int
257g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
258{
259	struct g_event *ep;
260	void *p;
261	u_int n;
262
263	g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
264	    func, arg, flag, wakeup);
265	KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
266	    ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
267	ep = g_malloc(sizeof *ep, flag | M_ZERO);
268	if (ep == NULL)
269		return (ENOMEM);
270	ep->flag = wuflag;
271	for (n = 0; n < G_N_EVENTREFS; n++) {
272		p = va_arg(ap, void *);
273		if (p == NULL)
274			break;
275		g_trace(G_T_TOPOLOGY, "  ref %p", p);
276		ep->ref[n] = p;
277	}
278	KASSERT(p == NULL, ("Too many references to event"));
279	ep->func = func;
280	ep->arg = arg;
281	mtx_lock(&g_eventlock);
282	g_pending_events++;
283	TAILQ_INSERT_TAIL(&g_events, ep, events);
284	mtx_unlock(&g_eventlock);
285	wakeup(&g_wait_event);
286	if (epp != NULL)
287		*epp = ep;
288	curthread->td_pflags |= TDP_GEOM;
289	return (0);
290}
291
292int
293g_post_event(g_event_t *func, void *arg, int flag, ...)
294{
295	va_list ap;
296	int i;
297
298	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
299	    ("Wrong flag to g_post_event"));
300	va_start(ap, flag);
301	i = g_post_event_x(func, arg, flag, 0, NULL, ap);
302	va_end(ap);
303	return (i);
304}
305
306void
307g_do_wither() {
308
309	g_wither_work = 1;
310	wakeup(&g_wait_event);
311}
312
313/*
314 * XXX: It might actually be useful to call this function with topology held.
315 * XXX: This would ensure that the event gets created before anything else
316 * XXX: changes.  At present all users have a handle on things in some other
317 * XXX: way, so this remains an XXX for now.
318 */
319
320int
321g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
322{
323	va_list ap;
324	struct g_event *ep;
325	int error;
326
327	g_topology_assert_not();
328	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
329	    ("Wrong flag to g_post_event"));
330	va_start(ap, flag);
331	error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
332	va_end(ap);
333	if (error)
334		return (error);
335	do
336		tsleep(ep, PRIBIO, "g_waitfor_event", hz);
337	while (!(ep->flag & EV_DONE));
338	if (ep->flag & EV_CANCELED)
339		error = EAGAIN;
340	g_free(ep);
341	return (error);
342}
343
344void
345g_event_init()
346{
347
348	mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
349}
350