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("$FreeBSD$");
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#define EV_INPROGRESS	0x10000
80
81void
82g_waitidle(void)
83{
84
85	g_topology_assert_not();
86	mtx_assert(&Giant, MA_NOTOWNED);
87
88	mtx_lock(&g_eventlock);
89	while (!TAILQ_EMPTY(&g_events))
90		msleep(&g_pending_events, &g_eventlock, PPAUSE,
91		    "g_waitidle", hz/5);
92	mtx_unlock(&g_eventlock);
93	curthread->td_pflags &= ~TDP_GEOM;
94}
95
96#if 0
97void
98g_waitidlelock(void)
99{
100
101	g_topology_assert();
102	mtx_lock(&g_eventlock);
103	while (!TAILQ_EMPTY(&g_events)) {
104		g_topology_unlock();
105		msleep(&g_pending_events, &g_eventlock, PPAUSE,
106		    "g_waitidlel", hz/5);
107		g_topology_lock();
108	}
109	mtx_unlock(&g_eventlock);
110}
111#endif
112
113struct g_attrchanged_args {
114	struct g_provider *pp;
115	const char *attr;
116};
117
118static void
119g_attr_changed_event(void *arg, int flag)
120{
121	struct g_attrchanged_args *args;
122	struct g_provider *pp;
123	struct g_consumer *cp;
124	struct g_consumer *next_cp;
125
126	args = arg;
127	pp = args->pp;
128
129	g_topology_assert();
130	if (flag != EV_CANCEL && g_shutdown == 0) {
131
132		/*
133		 * Tell all consumers of the change.
134		 */
135		LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, next_cp) {
136			if (cp->geom->attrchanged != NULL)
137				cp->geom->attrchanged(cp, args->attr);
138		}
139	}
140	g_free(args);
141}
142
143int
144g_attr_changed(struct g_provider *pp, const char *attr, int flag)
145{
146	struct g_attrchanged_args *args;
147	int error;
148
149	args = g_malloc(sizeof *args, flag);
150	if (args == NULL)
151		return (ENOMEM);
152	args->pp = pp;
153	args->attr = attr;
154	error = g_post_event(g_attr_changed_event, args, flag, pp, NULL);
155	if (error != 0)
156		g_free(args);
157	return (error);
158}
159
160void
161g_orphan_provider(struct g_provider *pp, int error)
162{
163
164	/* G_VALID_PROVIDER(pp)  We likely lack topology lock */
165	g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
166	    pp, pp->name, error);
167	KASSERT(error != 0,
168	    ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
169	     pp, pp->name));
170
171	pp->error = error;
172	mtx_lock(&g_eventlock);
173	KASSERT(!(pp->flags & G_PF_ORPHAN),
174	    ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
175	pp->flags |= G_PF_ORPHAN;
176	TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
177	mtx_unlock(&g_eventlock);
178	wakeup(&g_wait_event);
179}
180
181/*
182 * This function is called once on each provider which the event handler
183 * finds on its g_doorstep.
184 */
185
186static void
187g_orphan_register(struct g_provider *pp)
188{
189	struct g_consumer *cp, *cp2;
190	int wf;
191
192	g_topology_assert();
193	G_VALID_PROVIDER(pp);
194	g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
195
196	g_cancel_event(pp);
197
198	wf = pp->flags & G_PF_WITHER;
199	pp->flags &= ~G_PF_WITHER;
200
201	/*
202	 * Tell all consumers the bad news.
203	 * Don't be surprised if they self-destruct.
204	 */
205	LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, cp2) {
206		KASSERT(cp->geom->orphan != NULL,
207		    ("geom %s has no orphan, class %s",
208		    cp->geom->name, cp->geom->class->name));
209		/*
210		 * XXX: g_dev_orphan method does deferred destroying
211		 * and it is possible, that other event could already
212		 * call the orphan method. Check consumer's flags to
213		 * do not schedule it twice.
214		 */
215		if (cp->flags & G_CF_ORPHAN)
216			continue;
217		cp->flags |= G_CF_ORPHAN;
218		cp->geom->orphan(cp);
219	}
220	if (LIST_EMPTY(&pp->consumers) && wf)
221		g_destroy_provider(pp);
222	else
223		pp->flags |= wf;
224#ifdef notyet
225	cp = LIST_FIRST(&pp->consumers);
226	if (cp != NULL)
227		return;
228	if (pp->geom->flags & G_GEOM_WITHER)
229		g_destroy_provider(pp);
230#endif
231}
232
233static int
234one_event(void)
235{
236	struct g_event *ep;
237	struct g_provider *pp;
238
239	g_topology_assert();
240	mtx_lock(&g_eventlock);
241	TAILQ_FOREACH(pp, &g_doorstep, orphan) {
242		if (pp->nstart == pp->nend)
243			break;
244	}
245	if (pp != NULL) {
246		G_VALID_PROVIDER(pp);
247		TAILQ_REMOVE(&g_doorstep, pp, orphan);
248		mtx_unlock(&g_eventlock);
249		g_orphan_register(pp);
250		return (1);
251	}
252
253	ep = TAILQ_FIRST(&g_events);
254	if (ep == NULL) {
255		wakeup(&g_pending_events);
256		return (0);
257	}
258	if (ep->flag & EV_INPROGRESS) {
259		mtx_unlock(&g_eventlock);
260		return (1);
261	}
262	ep->flag |= EV_INPROGRESS;
263	mtx_unlock(&g_eventlock);
264	g_topology_assert();
265	ep->func(ep->arg, 0);
266	g_topology_assert();
267	mtx_lock(&g_eventlock);
268	TAILQ_REMOVE(&g_events, ep, events);
269	ep->flag &= ~EV_INPROGRESS;
270	if (ep->flag & EV_WAKEUP) {
271		ep->flag |= EV_DONE;
272		mtx_unlock(&g_eventlock);
273		wakeup(ep);
274	} else {
275		mtx_unlock(&g_eventlock);
276		g_free(ep);
277	}
278	return (1);
279}
280
281void
282g_run_events()
283{
284
285	for (;;) {
286		g_topology_lock();
287		while (one_event())
288			;
289		mtx_assert(&g_eventlock, MA_OWNED);
290		if (g_wither_work) {
291			g_wither_work = 0;
292			mtx_unlock(&g_eventlock);
293			g_wither_washer();
294			g_topology_unlock();
295		} else {
296			g_topology_unlock();
297			msleep(&g_wait_event, &g_eventlock, PRIBIO | PDROP,
298			    "-", TAILQ_EMPTY(&g_doorstep) ? 0 : hz / 10);
299		}
300	}
301	/* NOTREACHED */
302}
303
304void
305g_cancel_event(void *ref)
306{
307	struct g_event *ep, *epn;
308	struct g_provider *pp;
309	u_int n;
310
311	mtx_lock(&g_eventlock);
312	TAILQ_FOREACH(pp, &g_doorstep, orphan) {
313		if (pp != ref)
314			continue;
315		TAILQ_REMOVE(&g_doorstep, pp, orphan);
316		break;
317	}
318	TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
319		if (ep->flag & EV_INPROGRESS)
320			continue;
321		for (n = 0; n < G_N_EVENTREFS; n++) {
322			if (ep->ref[n] == NULL)
323				break;
324			if (ep->ref[n] != ref)
325				continue;
326			TAILQ_REMOVE(&g_events, ep, events);
327			ep->func(ep->arg, EV_CANCEL);
328			mtx_assert(&g_eventlock, MA_OWNED);
329			if (ep->flag & EV_WAKEUP) {
330				ep->flag |= (EV_DONE|EV_CANCELED);
331				wakeup(ep);
332			} else {
333				g_free(ep);
334			}
335			break;
336		}
337	}
338	if (TAILQ_EMPTY(&g_events))
339		wakeup(&g_pending_events);
340	mtx_unlock(&g_eventlock);
341}
342
343static int
344g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
345{
346	struct g_event *ep;
347	void *p;
348	u_int n;
349
350	g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
351	    func, arg, flag, wuflag);
352	KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
353	    ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
354	ep = g_malloc(sizeof *ep, flag | M_ZERO);
355	if (ep == NULL)
356		return (ENOMEM);
357	ep->flag = wuflag;
358	for (n = 0; n < G_N_EVENTREFS; n++) {
359		p = va_arg(ap, void *);
360		if (p == NULL)
361			break;
362		g_trace(G_T_TOPOLOGY, "  ref %p", p);
363		ep->ref[n] = p;
364	}
365	KASSERT(p == NULL, ("Too many references to event"));
366	ep->func = func;
367	ep->arg = arg;
368	mtx_lock(&g_eventlock);
369	TAILQ_INSERT_TAIL(&g_events, ep, events);
370	mtx_unlock(&g_eventlock);
371	wakeup(&g_wait_event);
372	if (epp != NULL)
373		*epp = ep;
374	curthread->td_pflags |= TDP_GEOM;
375	return (0);
376}
377
378int
379g_post_event(g_event_t *func, void *arg, int flag, ...)
380{
381	va_list ap;
382	int i;
383
384	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
385	    ("Wrong flag to g_post_event"));
386	va_start(ap, flag);
387	i = g_post_event_x(func, arg, flag, 0, NULL, ap);
388	va_end(ap);
389	return (i);
390}
391
392void
393g_do_wither()
394{
395
396	mtx_lock(&g_eventlock);
397	g_wither_work = 1;
398	mtx_unlock(&g_eventlock);
399	wakeup(&g_wait_event);
400}
401
402/*
403 * XXX: It might actually be useful to call this function with topology held.
404 * XXX: This would ensure that the event gets created before anything else
405 * XXX: changes.  At present all users have a handle on things in some other
406 * XXX: way, so this remains an XXX for now.
407 */
408
409int
410g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
411{
412	va_list ap;
413	struct g_event *ep;
414	int error;
415
416	g_topology_assert_not();
417	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
418	    ("Wrong flag to g_post_event"));
419	va_start(ap, flag);
420	error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
421	va_end(ap);
422	if (error)
423		return (error);
424
425	mtx_lock(&g_eventlock);
426	while (!(ep->flag & EV_DONE))
427		msleep(ep, &g_eventlock, PRIBIO, "g_waitfor_event", hz);
428	if (ep->flag & EV_CANCELED)
429		error = EAGAIN;
430	mtx_unlock(&g_eventlock);
431
432	g_free(ep);
433	return (error);
434}
435
436void
437g_event_init()
438{
439
440	mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
441}
442