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 <machine/stdarg.h> 51 #include <sys/errno.h> 52 #include <sys/time.h> 53 #include <geom/geom.h> 54 #include <geom/geom_int.h> 55 56 TAILQ_HEAD(event_tailq_head, g_event); 57 58 static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events); 59 static u_int g_pending_events; 60 static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep); 61 static struct mtx g_eventlock; 62 static struct sx g_eventstall; 63 64 #define G_N_EVENTREFS 20 65 66 struct g_event { 67 TAILQ_ENTRY(g_event) events; 68 g_event_t *func; 69 void *arg; 70 int flag; 71 void *ref[G_N_EVENTREFS]; 72 }; 73 74 #define EV_DONE 0x80000 75 #define EV_WAKEUP 0x40000 76 #define EV_CANCELED 0x20000 77 78 void 79 g_waitidle(void) 80 { 81 82 while (g_pending_events) 83 tsleep(&g_pending_events, PPAUSE, "g_waitidle", hz/5); 84 } 85 86 void 87 g_stall_events(void) 88 { 89 90 sx_xlock(&g_eventstall); 91 } 92 93 void 94 g_release_events(void) 95 { 96 97 sx_xunlock(&g_eventstall); 98 } 99 100 void 101 g_orphan_provider(struct g_provider *pp, int error) 102 { 103 104 g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)", 105 pp, pp->name, error); 106 KASSERT(error != 0, 107 ("g_orphan_provider(%p(%s), 0) error must be non-zero\n", 108 pp, pp->name)); 109 110 pp->error = error; 111 mtx_lock(&g_eventlock); 112 KASSERT(!(pp->flags & G_PF_ORPHAN), 113 ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name)); 114 pp->flags |= G_PF_ORPHAN; 115 TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan); 116 mtx_unlock(&g_eventlock); 117 wakeup(&g_wait_event); 118 } 119 120 /* 121 * This function is called once on each provider which the event handler 122 * finds on its g_doorstep. 123 */ 124 125 static void 126 g_orphan_register(struct g_provider *pp) 127 { 128 struct g_consumer *cp, *cp2; 129 130 g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name); 131 g_topology_assert(); 132 133 /* 134 * Tell all consumers the bad news. 135 * Don't be surprised if they self-destruct. 136 */ 137 cp = LIST_FIRST(&pp->consumers); 138 while (cp != NULL) { 139 cp2 = LIST_NEXT(cp, consumers); 140 KASSERT(cp->geom->orphan != NULL, 141 ("geom %s has no orphan, class %s", 142 cp->geom->name, cp->geom->class->name)); 143 cp->geom->orphan(cp); 144 cp = cp2; 145 } 146 if (LIST_EMPTY(&pp->consumers) && (pp->flags & G_PF_WITHER)) 147 g_destroy_provider(pp); 148 #ifdef notyet 149 cp = LIST_FIRST(&pp->consumers); 150 if (cp != NULL) 151 return; 152 if (pp->geom->flags & G_GEOM_WITHER) 153 g_destroy_provider(pp); 154 #endif 155 } 156 157 static int 158 one_event(void) 159 { 160 struct g_event *ep; 161 struct g_provider *pp; 162 163 sx_xlock(&g_eventstall); 164 g_topology_lock(); 165 for (;;) { 166 mtx_lock(&g_eventlock); 167 pp = TAILQ_FIRST(&g_doorstep); 168 if (pp != NULL) 169 TAILQ_REMOVE(&g_doorstep, pp, orphan); 170 mtx_unlock(&g_eventlock); 171 if (pp == NULL) 172 break; 173 g_orphan_register(pp); 174 } 175 mtx_lock(&g_eventlock); 176 ep = TAILQ_FIRST(&g_events); 177 if (ep == NULL) { 178 mtx_unlock(&g_eventlock); 179 g_topology_unlock(); 180 sx_xunlock(&g_eventstall); 181 return (0); 182 } 183 TAILQ_REMOVE(&g_events, ep, events); 184 mtx_unlock(&g_eventlock); 185 g_topology_assert(); 186 ep->func(ep->arg, 0); 187 g_topology_assert(); 188 if (ep->flag & EV_WAKEUP) { 189 ep->flag |= EV_DONE; 190 wakeup(ep); 191 } else { 192 g_free(ep); 193 } 194 g_pending_events--; 195 if (g_pending_events == 0) 196 wakeup(&g_pending_events); 197 g_topology_unlock(); 198 sx_xunlock(&g_eventstall); 199 return (1); 200 } 201 202 void 203 g_run_events() 204 { 205 206 while (one_event()) 207 ; 208 } 209 210 void 211 g_cancel_event(void *ref) 212 { 213 struct g_event *ep, *epn; 214 struct g_provider *pp; 215 u_int n; 216 217 mtx_lock(&g_eventlock); 218 TAILQ_FOREACH(pp, &g_doorstep, orphan) { 219 if (pp != ref) 220 continue; 221 TAILQ_REMOVE(&g_doorstep, pp, orphan); 222 break; 223 } 224 for (ep = TAILQ_FIRST(&g_events); ep != NULL; ep = epn) { 225 epn = TAILQ_NEXT(ep, events); 226 for (n = 0; n < G_N_EVENTREFS; n++) { 227 if (ep->ref[n] == NULL) 228 break; 229 if (ep->ref[n] == ref) { 230 TAILQ_REMOVE(&g_events, ep, events); 231 ep->func(ep->arg, EV_CANCEL); 232 if (ep->flag & EV_WAKEUP) { 233 ep->flag |= EV_DONE; 234 ep->flag |= EV_CANCELED; 235 wakeup(ep); 236 } else { 237 g_free(ep); 238 } 239 break; 240 } 241 } 242 } 243 mtx_unlock(&g_eventlock); 244 } 245 246 static int 247 g_post_event_x(g_event_t *func, void *arg, int flag, struct g_event **epp, va_list ap) 248 { 249 struct g_event *ep; 250 void *p; 251 u_int n; 252 253 g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d)", func, arg, flag); 254 ep = g_malloc(sizeof *ep, flag | M_ZERO); 255 if (ep == NULL) 256 return (ENOMEM); 257 ep->flag = flag; 258 for (n = 0; n < G_N_EVENTREFS; n++) { 259 p = va_arg(ap, void *); 260 if (p == NULL) 261 break; 262 g_trace(G_T_TOPOLOGY, " ref %p", p); 263 ep->ref[n] = p; 264 } 265 KASSERT(p == NULL, ("Too many references to event")); 266 ep->func = func; 267 ep->arg = arg; 268 mtx_lock(&g_eventlock); 269 g_pending_events++; 270 TAILQ_INSERT_TAIL(&g_events, ep, events); 271 mtx_unlock(&g_eventlock); 272 wakeup(&g_wait_event); 273 if (epp != NULL) 274 *epp = ep; 275 return (0); 276 } 277 278 int 279 g_post_event(g_event_t *func, void *arg, int flag, ...) 280 { 281 va_list ap; 282 int i; 283 284 KASSERT(flag == M_WAITOK || flag == M_NOWAIT, 285 ("Wrong flag to g_post_event")); 286 va_start(ap, flag); 287 i = g_post_event_x(func, arg, flag, NULL, ap); 288 va_end(ap); 289 return (i); 290 } 291 292 293 /* 294 * XXX: It might actually be useful to call this function with topology held. 295 * XXX: This would ensure that the event gets created before anything else 296 * XXX: changes. At present all users have a handle on things in some other 297 * XXX: way, so this remains an XXX for now. 298 */ 299 300 int 301 g_waitfor_event(g_event_t *func, void *arg, int flag, ...) 302 { 303 va_list ap; 304 struct g_event *ep; 305 int error; 306 307 /* g_topology_assert_not(); */ 308 KASSERT(flag == M_WAITOK || flag == M_NOWAIT, 309 ("Wrong flag to g_post_event")); 310 va_start(ap, flag); 311 error = g_post_event_x(func, arg, flag | EV_WAKEUP, &ep, ap); 312 va_end(ap); 313 if (error) 314 return (error); 315 do 316 tsleep(ep, PRIBIO, "g_waitfor_event", hz); 317 while (!(ep->flag & EV_DONE)); 318 if (ep->flag & EV_CANCELED) 319 error = EAGAIN; 320 g_free(ep); 321 return (error); 322 } 323 324 void 325 g_event_init() 326 { 327 328 mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF); 329 sx_init(&g_eventstall, "GEOM event stalling"); 330 } 331