xref: /freebsd/sys/geom/geom_event.c (revision 195ebc7e9e4b129de810833791a19dfb4349d6a9)
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 
58 TAILQ_HEAD(event_tailq_head, g_event);
59 
60 static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
61 static u_int g_pending_events;
62 static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
63 static struct mtx g_eventlock;
64 static int g_wither_work;
65 
66 #define G_N_EVENTREFS		20
67 
68 struct 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 
80 void
81 g_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
96 void
97 g_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 
112 void
113 g_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 
138 static void
139 g_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 
179 static int
180 one_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 
226 void
227 g_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 
243 void
244 g_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 
280 static int
281 g_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 
315 int
316 g_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 
329 void
330 g_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 
343 int
344 g_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 
367 void
368 g_event_init()
369 {
370 
371 	mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
372 }
373