xref: /freebsd/sys/geom/geom_event.c (revision 1de7b4b805ddbf2429da511c053686ac4591ed89)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
3  *
4  * Copyright (c) 2002 Poul-Henning Kamp
5  * Copyright (c) 2002 Networks Associates Technology, Inc.
6  * All rights reserved.
7  *
8  * This software was developed for the FreeBSD Project by Poul-Henning Kamp
9  * and NAI Labs, the Security Research Division of Network Associates, Inc.
10  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
11  * DARPA CHATS research program.
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  * 1. Redistributions of source code must retain the above copyright
17  *    notice, this list of conditions and the following disclaimer.
18  * 2. Redistributions in binary form must reproduce the above copyright
19  *    notice, this list of conditions and the following disclaimer in the
20  *    documentation and/or other materials provided with the distribution.
21  * 3. The names of the authors may not be used to endorse or promote
22  *    products derived from this software without specific prior written
23  *    permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35  * SUCH DAMAGE.
36  */
37 
38 /*
39  * XXX: How do we in general know that objects referenced in events
40  * have not been destroyed before we get around to handle the event ?
41  */
42 
43 #include <sys/cdefs.h>
44 __FBSDID("$FreeBSD$");
45 
46 #include <sys/param.h>
47 #include <sys/malloc.h>
48 #include <sys/systm.h>
49 #include <sys/kernel.h>
50 #include <sys/lock.h>
51 #include <sys/mutex.h>
52 #include <sys/proc.h>
53 #include <sys/errno.h>
54 #include <sys/time.h>
55 #include <geom/geom.h>
56 #include <geom/geom_int.h>
57 
58 #include <machine/stdarg.h>
59 
60 TAILQ_HEAD(event_tailq_head, g_event);
61 
62 static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
63 static u_int g_pending_events;
64 static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
65 static struct mtx g_eventlock;
66 static int g_wither_work;
67 
68 #define G_N_EVENTREFS		20
69 
70 struct g_event {
71 	TAILQ_ENTRY(g_event)	events;
72 	g_event_t		*func;
73 	void			*arg;
74 	int			flag;
75 	void			*ref[G_N_EVENTREFS];
76 };
77 
78 #define EV_DONE		0x80000
79 #define EV_WAKEUP	0x40000
80 #define EV_CANCELED	0x20000
81 #define EV_INPROGRESS	0x10000
82 
83 void
84 g_waitidle(void)
85 {
86 
87 	g_topology_assert_not();
88 
89 	mtx_lock(&g_eventlock);
90 	while (!TAILQ_EMPTY(&g_events))
91 		msleep(&g_pending_events, &g_eventlock, PPAUSE,
92 		    "g_waitidle", hz/5);
93 	mtx_unlock(&g_eventlock);
94 	curthread->td_pflags &= ~TDP_GEOM;
95 }
96 
97 #if 0
98 void
99 g_waitidlelock(void)
100 {
101 
102 	g_topology_assert();
103 	mtx_lock(&g_eventlock);
104 	while (!TAILQ_EMPTY(&g_events)) {
105 		g_topology_unlock();
106 		msleep(&g_pending_events, &g_eventlock, PPAUSE,
107 		    "g_waitidlel", hz/5);
108 		g_topology_lock();
109 	}
110 	mtx_unlock(&g_eventlock);
111 }
112 #endif
113 
114 struct g_attrchanged_args {
115 	struct g_provider *pp;
116 	const char *attr;
117 };
118 
119 static void
120 g_attr_changed_event(void *arg, int flag)
121 {
122 	struct g_attrchanged_args *args;
123 	struct g_provider *pp;
124 	struct g_consumer *cp;
125 	struct g_consumer *next_cp;
126 
127 	args = arg;
128 	pp = args->pp;
129 
130 	g_topology_assert();
131 	if (flag != EV_CANCEL && g_shutdown == 0) {
132 
133 		/*
134 		 * Tell all consumers of the change.
135 		 */
136 		LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, next_cp) {
137 			if (cp->geom->attrchanged != NULL)
138 				cp->geom->attrchanged(cp, args->attr);
139 		}
140 	}
141 	g_free(args);
142 }
143 
144 int
145 g_attr_changed(struct g_provider *pp, const char *attr, int flag)
146 {
147 	struct g_attrchanged_args *args;
148 	int error;
149 
150 	args = g_malloc(sizeof *args, flag);
151 	if (args == NULL)
152 		return (ENOMEM);
153 	args->pp = pp;
154 	args->attr = attr;
155 	error = g_post_event(g_attr_changed_event, args, flag, pp, NULL);
156 	if (error != 0)
157 		g_free(args);
158 	return (error);
159 }
160 
161 void
162 g_orphan_provider(struct g_provider *pp, int error)
163 {
164 
165 	/* G_VALID_PROVIDER(pp)  We likely lack topology lock */
166 	g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
167 	    pp, pp->name, error);
168 	KASSERT(error != 0,
169 	    ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
170 	     pp, pp->name));
171 
172 	pp->error = error;
173 	mtx_lock(&g_eventlock);
174 	KASSERT(!(pp->flags & G_PF_ORPHAN),
175 	    ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
176 	pp->flags |= G_PF_ORPHAN;
177 	TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
178 	mtx_unlock(&g_eventlock);
179 	wakeup(&g_wait_event);
180 }
181 
182 /*
183  * This function is called once on each provider which the event handler
184  * finds on its g_doorstep.
185  */
186 
187 static void
188 g_orphan_register(struct g_provider *pp)
189 {
190 	struct g_consumer *cp, *cp2;
191 	int wf;
192 
193 	g_topology_assert();
194 	G_VALID_PROVIDER(pp);
195 	g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
196 
197 	g_cancel_event(pp);
198 
199 	wf = pp->flags & G_PF_WITHER;
200 	pp->flags &= ~G_PF_WITHER;
201 
202 	/*
203 	 * Tell all consumers the bad news.
204 	 * Don't be surprised if they self-destruct.
205 	 */
206 	LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, cp2) {
207 		KASSERT(cp->geom->orphan != NULL,
208 		    ("geom %s has no orphan, class %s",
209 		    cp->geom->name, cp->geom->class->name));
210 		/*
211 		 * XXX: g_dev_orphan method does deferred destroying
212 		 * and it is possible, that other event could already
213 		 * call the orphan method. Check consumer's flags to
214 		 * do not schedule it twice.
215 		 */
216 		if (cp->flags & G_CF_ORPHAN)
217 			continue;
218 		cp->flags |= G_CF_ORPHAN;
219 		cp->geom->orphan(cp);
220 	}
221 	if (LIST_EMPTY(&pp->consumers) && wf)
222 		g_destroy_provider(pp);
223 	else
224 		pp->flags |= wf;
225 #ifdef notyet
226 	cp = LIST_FIRST(&pp->consumers);
227 	if (cp != NULL)
228 		return;
229 	if (pp->geom->flags & G_GEOM_WITHER)
230 		g_destroy_provider(pp);
231 #endif
232 }
233 
234 static int
235 one_event(void)
236 {
237 	struct g_event *ep;
238 	struct g_provider *pp;
239 
240 	g_topology_assert();
241 	mtx_lock(&g_eventlock);
242 	TAILQ_FOREACH(pp, &g_doorstep, orphan) {
243 		if (pp->nstart == pp->nend)
244 			break;
245 	}
246 	if (pp != NULL) {
247 		G_VALID_PROVIDER(pp);
248 		TAILQ_REMOVE(&g_doorstep, pp, orphan);
249 		mtx_unlock(&g_eventlock);
250 		g_orphan_register(pp);
251 		return (1);
252 	}
253 
254 	ep = TAILQ_FIRST(&g_events);
255 	if (ep == NULL) {
256 		wakeup(&g_pending_events);
257 		return (0);
258 	}
259 	if (ep->flag & EV_INPROGRESS) {
260 		mtx_unlock(&g_eventlock);
261 		return (1);
262 	}
263 	ep->flag |= EV_INPROGRESS;
264 	mtx_unlock(&g_eventlock);
265 	g_topology_assert();
266 	ep->func(ep->arg, 0);
267 	g_topology_assert();
268 	mtx_lock(&g_eventlock);
269 	TAILQ_REMOVE(&g_events, ep, events);
270 	ep->flag &= ~EV_INPROGRESS;
271 	if (ep->flag & EV_WAKEUP) {
272 		ep->flag |= EV_DONE;
273 		mtx_unlock(&g_eventlock);
274 		wakeup(ep);
275 	} else {
276 		mtx_unlock(&g_eventlock);
277 		g_free(ep);
278 	}
279 	return (1);
280 }
281 
282 void
283 g_run_events()
284 {
285 
286 	for (;;) {
287 		g_topology_lock();
288 		while (one_event())
289 			;
290 		mtx_assert(&g_eventlock, MA_OWNED);
291 		if (g_wither_work) {
292 			g_wither_work = 0;
293 			mtx_unlock(&g_eventlock);
294 			g_wither_washer();
295 			g_topology_unlock();
296 		} else {
297 			g_topology_unlock();
298 			msleep(&g_wait_event, &g_eventlock, PRIBIO | PDROP,
299 			    "-", TAILQ_EMPTY(&g_doorstep) ? 0 : hz / 10);
300 		}
301 	}
302 	/* NOTREACHED */
303 }
304 
305 void
306 g_cancel_event(void *ref)
307 {
308 	struct g_event *ep, *epn;
309 	struct g_provider *pp;
310 	u_int n;
311 
312 	mtx_lock(&g_eventlock);
313 	TAILQ_FOREACH(pp, &g_doorstep, orphan) {
314 		if (pp != ref)
315 			continue;
316 		TAILQ_REMOVE(&g_doorstep, pp, orphan);
317 		break;
318 	}
319 	TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
320 		if (ep->flag & EV_INPROGRESS)
321 			continue;
322 		for (n = 0; n < G_N_EVENTREFS; n++) {
323 			if (ep->ref[n] == NULL)
324 				break;
325 			if (ep->ref[n] != ref)
326 				continue;
327 			TAILQ_REMOVE(&g_events, ep, events);
328 			ep->func(ep->arg, EV_CANCEL);
329 			mtx_assert(&g_eventlock, MA_OWNED);
330 			if (ep->flag & EV_WAKEUP) {
331 				ep->flag |= (EV_DONE|EV_CANCELED);
332 				wakeup(ep);
333 			} else {
334 				g_free(ep);
335 			}
336 			break;
337 		}
338 	}
339 	if (TAILQ_EMPTY(&g_events))
340 		wakeup(&g_pending_events);
341 	mtx_unlock(&g_eventlock);
342 }
343 
344 static int
345 g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
346 {
347 	struct g_event *ep;
348 	void *p;
349 	u_int n;
350 
351 	g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
352 	    func, arg, flag, wuflag);
353 	KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
354 	    ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
355 	ep = g_malloc(sizeof *ep, flag | M_ZERO);
356 	if (ep == NULL)
357 		return (ENOMEM);
358 	ep->flag = wuflag;
359 	for (n = 0; n < G_N_EVENTREFS; n++) {
360 		p = va_arg(ap, void *);
361 		if (p == NULL)
362 			break;
363 		g_trace(G_T_TOPOLOGY, "  ref %p", p);
364 		ep->ref[n] = p;
365 	}
366 	KASSERT(p == NULL, ("Too many references to event"));
367 	ep->func = func;
368 	ep->arg = arg;
369 	mtx_lock(&g_eventlock);
370 	TAILQ_INSERT_TAIL(&g_events, ep, events);
371 	mtx_unlock(&g_eventlock);
372 	wakeup(&g_wait_event);
373 	if (epp != NULL)
374 		*epp = ep;
375 	curthread->td_pflags |= TDP_GEOM;
376 	return (0);
377 }
378 
379 int
380 g_post_event(g_event_t *func, void *arg, int flag, ...)
381 {
382 	va_list ap;
383 	int i;
384 
385 	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
386 	    ("Wrong flag to g_post_event"));
387 	va_start(ap, flag);
388 	i = g_post_event_x(func, arg, flag, 0, NULL, ap);
389 	va_end(ap);
390 	return (i);
391 }
392 
393 void
394 g_do_wither()
395 {
396 
397 	mtx_lock(&g_eventlock);
398 	g_wither_work = 1;
399 	mtx_unlock(&g_eventlock);
400 	wakeup(&g_wait_event);
401 }
402 
403 /*
404  * XXX: It might actually be useful to call this function with topology held.
405  * XXX: This would ensure that the event gets created before anything else
406  * XXX: changes.  At present all users have a handle on things in some other
407  * XXX: way, so this remains an XXX for now.
408  */
409 
410 int
411 g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
412 {
413 	va_list ap;
414 	struct g_event *ep;
415 	int error;
416 
417 	g_topology_assert_not();
418 	KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
419 	    ("Wrong flag to g_post_event"));
420 	va_start(ap, flag);
421 	error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
422 	va_end(ap);
423 	if (error)
424 		return (error);
425 
426 	mtx_lock(&g_eventlock);
427 	while (!(ep->flag & EV_DONE))
428 		msleep(ep, &g_eventlock, PRIBIO, "g_waitfor_event", hz);
429 	if (ep->flag & EV_CANCELED)
430 		error = EAGAIN;
431 	mtx_unlock(&g_eventlock);
432 
433 	g_free(ep);
434 	return (error);
435 }
436 
437 void
438 g_event_init()
439 {
440 
441 	mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
442 }
443