geom_event.c revision 146353 
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 146353 2005-05-18 21:53:08Z pjd $");
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_waitidlelock(void)
94{
95
96	g_topology_assert();
97	while (g_pending_events) {
98		g_topology_unlock();
99		tsleep(&g_pending_events, PPAUSE, "g_waitidle", hz/5);
100		g_topology_lock();
101	}
102}
103
104void
105g_orphan_provider(struct g_provider *pp, int error)
106{
107
108	/* G_VALID_PROVIDER(pp)  We likely lack topology lock */
109	g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
110	    pp, pp->name, error);
111	KASSERT(error != 0,
112	    ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
113	     pp, pp->name));
114
115	pp->error = error;
116	mtx_lock(&g_eventlock);
117	KASSERT(!(pp->flags & G_PF_ORPHAN),
118	    ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
119	pp->flags |= G_PF_ORPHAN;
120	TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
121	mtx_unlock(&g_eventlock);
122	wakeup(&g_wait_event);
123}
124
125/*
126 * This function is called once on each provider which the event handler
127 * finds on its g_doorstep.
128 */
129
130static void
131g_orphan_register(struct g_provider *pp)
132{
133	struct g_consumer *cp, *cp2;
134	int wf;
135
136	g_topology_assert();
137	G_VALID_PROVIDER(pp);
138	g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
139
140	wf = pp->flags & G_PF_WITHER;
141	pp->flags &= ~G_PF_WITHER;
142
143	/*
144	 * Tell all consumers the bad news.
145	 * Don't be surprised if they self-destruct.
146	 */
147	cp = LIST_FIRST(&pp->consumers);
148	while (cp != NULL) {
149		cp2 = LIST_NEXT(cp, consumers);
150		KASSERT(cp->geom->orphan != NULL,
151		    ("geom %s has no orphan, class %s",
152		    cp->geom->name, cp->geom->class->name));
153		cp->geom->orphan(cp);
154		cp = cp2;
155	}
156	if (LIST_EMPTY(&pp->consumers) && wf)
157		g_destroy_provider(pp);
158	else
159		pp->flags |= wf;
160#ifdef notyet
161	cp = LIST_FIRST(&pp->consumers);
162	if (cp != NULL)
163		return;
164	if (pp->geom->flags & G_GEOM_WITHER)
165		g_destroy_provider(pp);
166#endif
167}
168
169static int
170one_event(void)
171{
172	struct g_event *ep;
173	struct g_provider *pp;
174
175	g_topology_lock();
176	for (;;) {
177		mtx_lock(&g_eventlock);
178		pp = TAILQ_FIRST(&g_doorstep);
179		if (pp != NULL) {
180			G_VALID_PROVIDER(pp);
181			TAILQ_REMOVE(&g_doorstep, pp, orphan);
182		}
183		mtx_unlock(&g_eventlock);
184		if (pp == NULL)
185			break;
186		g_orphan_register(pp);
187	}
188	mtx_lock(&g_eventlock);
189	ep = TAILQ_FIRST(&g_events);
190	if (ep == NULL) {
191		mtx_unlock(&g_eventlock);
192		g_topology_unlock();
193		return (0);
194	}
195	TAILQ_REMOVE(&g_events, ep, events);
196	mtx_unlock(&g_eventlock);
197	g_topology_assert();
198	ep->func(ep->arg, 0);
199	g_topology_assert();
200	if (ep->flag & EV_WAKEUP) {
201		ep->flag |= EV_DONE;
202		wakeup(ep);
203	} else {
204		g_free(ep);
205	}
206	g_pending_events--;
207	if (g_pending_events == 0)
208		wakeup(&g_pending_events);
209	g_topology_unlock();
210	return (1);
211}
212
213void
214g_run_events()
215{
216	int i;
217
218	while (one_event())
219		;
220	g_topology_lock();
221	i = g_wither_work;
222	while (i) {
223		i = g_wither_washer();
224		g_wither_work = i & 1;
225		i &= 2;
226	}
227	g_topology_unlock();
228}
229
230void
231g_cancel_event(void *ref)
232{
233	struct g_event *ep, *epn;
234	struct g_provider *pp;
235	u_int n;
236
237	mtx_lock(&g_eventlock);
238	TAILQ_FOREACH(pp, &g_doorstep, orphan) {
239		if (pp != ref)
240			continue;
241		TAILQ_REMOVE(&g_doorstep, pp, orphan);
242		break;
243	}
244	for (ep = TAILQ_FIRST(&g_events); ep != NULL; ep = epn) {
245		epn = TAILQ_NEXT(ep, events);
246		for (n = 0; n < G_N_EVENTREFS; n++) {
247			if (ep->ref[n] == NULL)
248				break;
249			if (ep->ref[n] == ref) {
250				TAILQ_REMOVE(&g_events, ep, events);
251				ep->func(ep->arg, EV_CANCEL);
252				if (ep->flag & EV_WAKEUP) {
253					ep->flag |= EV_DONE;
254					ep->flag |= EV_CANCELED;
255					wakeup(ep);
256				} else {
257					g_free(ep);
258				}
259				if (--g_pending_events == 0)
260					wakeup(&g_pending_events);
261				break;
262			}
263		}
264	}
265	mtx_unlock(&g_eventlock);
266}
267
268static int
269g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
270{
271	struct g_event *ep;
272	void *p;
273	u_int n;
274
275	g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
276	    func, arg, flag, wuflag);
277	KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
278	    ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
279	ep = g_malloc(sizeof *ep, flag | M_ZERO);
280	if (ep == NULL)
281		return (ENOMEM);
282	ep->flag = wuflag;
283	for (n = 0; n < G_N_EVENTREFS; n++) {
284		p = va_arg(ap, void *);
285		if (p == NULL)
286			break;
287		g_trace(G_T_TOPOLOGY, "  ref %p", p);
288		ep->ref[n] = p;
289	}
290	KASSERT(p == NULL, ("Too many references to event"));
291	ep->func = func;
292	ep->arg = arg;
293	mtx_lock(&g_eventlock);
294	g_pending_events++;
295	TAILQ_INSERT_TAIL(&g_events, ep, events);
296	mtx_unlock(&g_eventlock);
297	wakeup(&g_wait_event);
298	if (epp != NULL)
299		*epp = ep;
300	curthread->td_pflags |= TDP_GEOM;
301	return (0);
302}
303
304int
305g_post_event(g_event_t *func, void *arg, int flag, ...)
306{
307	va_list ap;
308	int i;
309
310	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
311	    ("Wrong flag to g_post_event"));
312	va_start(ap, flag);
313	i = g_post_event_x(func, arg, flag, 0, NULL, ap);
314	va_end(ap);
315	return (i);
316}
317
318void
319g_do_wither() {
320
321	g_wither_work = 1;
322	wakeup(&g_wait_event);
323}
324
325/*
326 * XXX: It might actually be useful to call this function with topology held.
327 * XXX: This would ensure that the event gets created before anything else
328 * XXX: changes.  At present all users have a handle on things in some other
329 * XXX: way, so this remains an XXX for now.
330 */
331
332int
333g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
334{
335	va_list ap;
336	struct g_event *ep;
337	int error;
338
339	g_topology_assert_not();
340	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
341	    ("Wrong flag to g_post_event"));
342	va_start(ap, flag);
343	error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
344	va_end(ap);
345	if (error)
346		return (error);
347	do
348		tsleep(ep, PRIBIO, "g_waitfor_event", hz);
349	while (!(ep->flag & EV_DONE));
350	if (ep->flag & EV_CANCELED)
351		error = EAGAIN;
352	g_free(ep);
353	return (error);
354}
355
356void
357g_event_init()
358{
359
360	mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
361}
362