geom_event.c revision 172354 
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 172354 2007-09-27 20:18:34Z 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	mtx_lock(&g_eventlock);
88	while (!TAILQ_EMPTY(&g_events))
89		msleep(&g_pending_events, &g_eventlock, PPAUSE,
90		    "g_waitidle", hz/5);
91	mtx_unlock(&g_eventlock);
92	curthread->td_pflags &= ~TDP_GEOM;
93}
94
95#if 0
96void
97g_waitidlelock(void)
98{
99
100	g_topology_assert();
101	mtx_lock(&g_eventlock);
102	while (!TAILQ_EMPTY(&g_events)) {
103		g_topology_unlock();
104		msleep(&g_pending_events, &g_eventlock, PPAUSE,
105		    "g_waitidlel", hz/5);
106		g_topology_lock();
107	}
108	mtx_unlock(&g_eventlock);
109}
110#endif
111
112void
113g_orphan_provider(struct g_provider *pp, int error)
114{
115
116	/* G_VALID_PROVIDER(pp)  We likely lack topology lock */
117	g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
118	    pp, pp->name, error);
119	KASSERT(error != 0,
120	    ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
121	     pp, pp->name));
122
123	pp->error = error;
124	mtx_lock(&g_eventlock);
125	KASSERT(!(pp->flags & G_PF_ORPHAN),
126	    ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
127	pp->flags |= G_PF_ORPHAN;
128	TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
129	mtx_unlock(&g_eventlock);
130	wakeup(&g_wait_event);
131}
132
133/*
134 * This function is called once on each provider which the event handler
135 * finds on its g_doorstep.
136 */
137
138static void
139g_orphan_register(struct g_provider *pp)
140{
141	struct g_consumer *cp, *cp2;
142	int wf;
143
144	g_topology_assert();
145	G_VALID_PROVIDER(pp);
146	g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
147
148	g_cancel_event(pp);
149
150	wf = pp->flags & G_PF_WITHER;
151	pp->flags &= ~G_PF_WITHER;
152
153	/*
154	 * Tell all consumers the bad news.
155	 * Don't be surprised if they self-destruct.
156	 */
157	cp = LIST_FIRST(&pp->consumers);
158	while (cp != NULL) {
159		cp2 = LIST_NEXT(cp, consumers);
160		KASSERT(cp->geom->orphan != NULL,
161		    ("geom %s has no orphan, class %s",
162		    cp->geom->name, cp->geom->class->name));
163		cp->geom->orphan(cp);
164		cp = cp2;
165	}
166	if (LIST_EMPTY(&pp->consumers) && wf)
167		g_destroy_provider(pp);
168	else
169		pp->flags |= wf;
170#ifdef notyet
171	cp = LIST_FIRST(&pp->consumers);
172	if (cp != NULL)
173		return;
174	if (pp->geom->flags & G_GEOM_WITHER)
175		g_destroy_provider(pp);
176#endif
177}
178
179static int
180one_event(void)
181{
182	struct g_event *ep;
183	struct g_provider *pp;
184
185	g_topology_lock();
186	for (;;) {
187		mtx_lock(&g_eventlock);
188		TAILQ_FOREACH(pp, &g_doorstep, orphan) {
189			if (pp->nstart == pp->nend)
190				break;
191		}
192		if (pp != NULL) {
193			G_VALID_PROVIDER(pp);
194			TAILQ_REMOVE(&g_doorstep, pp, orphan);
195		}
196		mtx_unlock(&g_eventlock);
197		if (pp == NULL)
198			break;
199		g_orphan_register(pp);
200	}
201	mtx_lock(&g_eventlock);
202	ep = TAILQ_FIRST(&g_events);
203	if (ep == NULL) {
204		wakeup(&g_pending_events);
205		mtx_unlock(&g_eventlock);
206		g_topology_unlock();
207		return (0);
208	}
209	mtx_unlock(&g_eventlock);
210	g_topology_assert();
211	ep->func(ep->arg, 0);
212	g_topology_assert();
213	mtx_lock(&g_eventlock);
214	TAILQ_REMOVE(&g_events, ep, events);
215	mtx_unlock(&g_eventlock);
216	if (ep->flag & EV_WAKEUP) {
217		ep->flag |= EV_DONE;
218		wakeup(ep);
219	} else {
220		g_free(ep);
221	}
222	g_topology_unlock();
223	return (1);
224}
225
226void
227g_run_events()
228{
229	int i;
230
231	while (one_event())
232		;
233	g_topology_lock();
234	i = g_wither_work;
235	while (i) {
236		i = g_wither_washer();
237		g_wither_work = i & 1;
238		i &= 2;
239	}
240	g_topology_unlock();
241}
242
243void
244g_cancel_event(void *ref)
245{
246	struct g_event *ep, *epn;
247	struct g_provider *pp;
248	u_int n;
249
250	mtx_lock(&g_eventlock);
251	TAILQ_FOREACH(pp, &g_doorstep, orphan) {
252		if (pp != ref)
253			continue;
254		TAILQ_REMOVE(&g_doorstep, pp, orphan);
255		break;
256	}
257	TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
258		for (n = 0; n < G_N_EVENTREFS; n++) {
259			if (ep->ref[n] == NULL)
260				break;
261			if (ep->ref[n] != ref)
262				continue;
263			TAILQ_REMOVE(&g_events, ep, events);
264			ep->func(ep->arg, EV_CANCEL);
265			mtx_assert(&g_eventlock, MA_OWNED);
266			if (ep->flag & EV_WAKEUP) {
267				ep->flag |= (EV_DONE|EV_CANCELED);
268				wakeup(ep);
269			} else {
270				g_free(ep);
271			}
272			break;
273		}
274	}
275	if (TAILQ_EMPTY(&g_events))
276		wakeup(&g_pending_events);
277	mtx_unlock(&g_eventlock);
278}
279
280static int
281g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
282{
283	struct g_event *ep;
284	void *p;
285	u_int n;
286
287	g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
288	    func, arg, flag, wuflag);
289	KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
290	    ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
291	ep = g_malloc(sizeof *ep, flag | M_ZERO);
292	if (ep == NULL)
293		return (ENOMEM);
294	ep->flag = wuflag;
295	for (n = 0; n < G_N_EVENTREFS; n++) {
296		p = va_arg(ap, void *);
297		if (p == NULL)
298			break;
299		g_trace(G_T_TOPOLOGY, "  ref %p", p);
300		ep->ref[n] = p;
301	}
302	KASSERT(p == NULL, ("Too many references to event"));
303	ep->func = func;
304	ep->arg = arg;
305	mtx_lock(&g_eventlock);
306	TAILQ_INSERT_TAIL(&g_events, ep, events);
307	mtx_unlock(&g_eventlock);
308	wakeup(&g_wait_event);
309	if (epp != NULL)
310		*epp = ep;
311	curthread->td_pflags |= TDP_GEOM;
312	return (0);
313}
314
315int
316g_post_event(g_event_t *func, void *arg, int flag, ...)
317{
318	va_list ap;
319	int i;
320
321	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
322	    ("Wrong flag to g_post_event"));
323	va_start(ap, flag);
324	i = g_post_event_x(func, arg, flag, 0, NULL, ap);
325	va_end(ap);
326	return (i);
327}
328
329void
330g_do_wither() {
331
332	g_wither_work = 1;
333	wakeup(&g_wait_event);
334}
335
336/*
337 * XXX: It might actually be useful to call this function with topology held.
338 * XXX: This would ensure that the event gets created before anything else
339 * XXX: changes.  At present all users have a handle on things in some other
340 * XXX: way, so this remains an XXX for now.
341 */
342
343int
344g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
345{
346	va_list ap;
347	struct g_event *ep;
348	int error;
349
350	g_topology_assert_not();
351	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
352	    ("Wrong flag to g_post_event"));
353	va_start(ap, flag);
354	error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
355	va_end(ap);
356	if (error)
357		return (error);
358	do
359		tsleep(ep, PRIBIO, "g_waitfor_event", hz);
360	while (!(ep->flag & EV_DONE));
361	if (ep->flag & EV_CANCELED)
362		error = EAGAIN;
363	g_free(ep);
364	return (error);
365}
366
367void
368g_event_init()
369{
370
371	mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
372}
373