The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/geom/geom_event.c

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    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  * $FreeBSD: releng/5.1/sys/geom/geom_event.c 114490 2003-05-02 05:26:19Z phk $
   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/param.h>
   44 #include <sys/malloc.h>
   45 #include <sys/systm.h>
   46 #include <sys/kernel.h>
   47 #include <sys/lock.h>
   48 #include <sys/mutex.h>
   49 #include <machine/stdarg.h>
   50 #include <sys/errno.h>
   51 #include <sys/time.h>
   52 #include <geom/geom.h>
   53 #include <geom/geom_int.h>
   54 
   55 TAILQ_HEAD(event_tailq_head, g_event);
   56 
   57 static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
   58 static u_int g_pending_events;
   59 static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
   60 static struct mtx g_eventlock;
   61 static struct sx g_eventstall;
   62 
   63 #define G_N_EVENTREFS           20
   64 
   65 struct g_event {
   66         TAILQ_ENTRY(g_event)    events;
   67         g_event_t               *func;
   68         void                    *arg;
   69         int                     flag;
   70         void                    *ref[G_N_EVENTREFS];
   71 };
   72 
   73 #define EV_DONE         0x80000
   74 #define EV_WAKEUP       0x40000
   75 #define EV_CANCELED     0x20000
   76 
   77 void
   78 g_waitidle(void)
   79 {
   80 
   81         while (g_pending_events)
   82                 tsleep(&g_pending_events, PPAUSE, "g_waitidle", hz/5);
   83 }
   84 
   85 void
   86 g_stall_events(void)
   87 {
   88 
   89         sx_xlock(&g_eventstall);
   90 }
   91 
   92 void
   93 g_release_events(void)
   94 {
   95 
   96         sx_xunlock(&g_eventstall);
   97 }
   98 
   99 void
  100 g_orphan_provider(struct g_provider *pp, int error)
  101 {
  102 
  103         g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
  104             pp, pp->name, error);
  105         KASSERT(error != 0,
  106             ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
  107              pp, pp->name));
  108         pp->error = error;
  109         mtx_lock(&g_eventlock);
  110         TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
  111         mtx_unlock(&g_eventlock);
  112         wakeup(&g_wait_event);
  113 }
  114 
  115 /*
  116  * This function is called once on each provider which the event handler
  117  * finds on its g_doorstep.
  118  */
  119 
  120 static void
  121 g_orphan_register(struct g_provider *pp)
  122 {
  123         struct g_consumer *cp, *cp2;
  124 
  125         g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
  126         g_topology_assert();
  127 
  128         /*
  129          * Tell all consumers the bad news.
  130          * Don't be surprised if they self-destruct.
  131          */
  132         cp = LIST_FIRST(&pp->consumers);
  133         while (cp != NULL) {
  134                 cp2 = LIST_NEXT(cp, consumers);
  135                 KASSERT(cp->geom->orphan != NULL,
  136                     ("geom %s has no orphan, class %s",
  137                     cp->geom->name, cp->geom->class->name));
  138                 cp->geom->orphan(cp);
  139                 cp = cp2;
  140         }
  141 #ifdef notyet
  142         cp = LIST_FIRST(&pp->consumers);
  143         if (cp != NULL)
  144                 return;
  145         if (pp->geom->flags & G_GEOM_WITHER)
  146                 g_destroy_provider(pp);
  147 #endif
  148 }
  149 
  150 static int
  151 one_event(void)
  152 {
  153         struct g_event *ep;
  154         struct g_provider *pp;
  155 
  156         sx_xlock(&g_eventstall);
  157         g_topology_lock();
  158         for (;;) {
  159                 mtx_lock(&g_eventlock);
  160                 pp = TAILQ_FIRST(&g_doorstep);
  161                 if (pp != NULL)
  162                         TAILQ_REMOVE(&g_doorstep, pp, orphan);
  163                 mtx_unlock(&g_eventlock);
  164                 if (pp == NULL)
  165                         break;
  166                 g_orphan_register(pp);
  167         }
  168         mtx_lock(&g_eventlock);
  169         ep = TAILQ_FIRST(&g_events);
  170         if (ep == NULL) {
  171                 mtx_unlock(&g_eventlock);
  172                 g_topology_unlock();
  173                 sx_xunlock(&g_eventstall);
  174                 return (0);
  175         }
  176         TAILQ_REMOVE(&g_events, ep, events);
  177         mtx_unlock(&g_eventlock);
  178         g_topology_assert();
  179         ep->func(ep->arg, 0);
  180         g_topology_assert();
  181         if (ep->flag & EV_WAKEUP) {
  182                 ep->flag |= EV_DONE;
  183                 wakeup(ep);
  184         } else {
  185                 g_free(ep);
  186         }
  187         g_pending_events--;
  188         if (g_pending_events == 0)
  189                 wakeup(&g_pending_events);
  190         g_topology_unlock();
  191         sx_xunlock(&g_eventstall);
  192         return (1);
  193 }
  194 
  195 void
  196 g_run_events()
  197 {
  198 
  199         while (one_event())
  200                 ;
  201 }
  202 
  203 void
  204 g_cancel_event(void *ref)
  205 {
  206         struct g_event *ep, *epn;
  207         struct g_provider *pp;
  208         u_int n;
  209 
  210         mtx_lock(&g_eventlock);
  211         TAILQ_FOREACH(pp, &g_doorstep, orphan) {
  212                 if (pp != ref)
  213                         continue;
  214                 TAILQ_REMOVE(&g_doorstep, pp, orphan);
  215                 break;
  216         }
  217         for (ep = TAILQ_FIRST(&g_events); ep != NULL; ep = epn) {
  218                 epn = TAILQ_NEXT(ep, events);
  219                 for (n = 0; n < G_N_EVENTREFS; n++) {
  220                         if (ep->ref[n] == NULL)
  221                                 break;
  222                         if (ep->ref[n] == ref) {
  223                                 TAILQ_REMOVE(&g_events, ep, events);
  224                                 ep->func(ep->arg, EV_CANCEL);
  225                                 if (ep->flag & EV_WAKEUP) {
  226                                         ep->flag |= EV_DONE;
  227                                         ep->flag |= EV_CANCELED;
  228                                         wakeup(ep);
  229                                 } else {
  230                                         g_free(ep);
  231                                 }
  232                                 break;
  233                         }
  234                 }
  235         }
  236         mtx_unlock(&g_eventlock);
  237 }
  238 
  239 static int
  240 g_post_event_x(g_event_t *func, void *arg, int flag, struct g_event **epp, va_list ap)
  241 {
  242         struct g_event *ep;
  243         void *p;
  244         u_int n;
  245 
  246         g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d", func, arg, flag);
  247         ep = g_malloc(sizeof *ep, flag | M_ZERO);
  248         if (ep == NULL)
  249                 return (ENOMEM);
  250         ep->flag = flag;
  251         for (n = 0; n < G_N_EVENTREFS; n++) {
  252                 p = va_arg(ap, void *);
  253                 if (p == NULL)
  254                         break;
  255                 g_trace(G_T_TOPOLOGY, "  ref %p", p);
  256                 ep->ref[n++] = p;
  257         }
  258         va_end(ap);
  259         KASSERT(p == NULL, ("Too many references to event"));
  260         ep->func = func;
  261         ep->arg = arg;
  262         mtx_lock(&g_eventlock);
  263         g_pending_events++;
  264         TAILQ_INSERT_TAIL(&g_events, ep, events);
  265         mtx_unlock(&g_eventlock);
  266         wakeup(&g_wait_event);
  267         if (epp != NULL)
  268                 *epp = ep;
  269         return (0);
  270 }
  271 
  272 int
  273 g_post_event(g_event_t *func, void *arg, int flag, ...)
  274 {
  275         va_list ap;
  276 
  277         va_start(ap, flag);
  278         KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
  279             ("Wrong flag to g_post_event"));
  280         return (g_post_event_x(func, arg, flag, NULL, ap));
  281 }
  282 
  283 
  284 /*
  285  * XXX: It might actually be useful to call this function with topology held.
  286  * XXX: This would ensure that the event gets created before anything else
  287  * XXX: changes.  At present all users have a handle on things in some other
  288  * XXX: way, so this remains an XXX for now.
  289  */
  290 
  291 int
  292 g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
  293 {
  294         va_list ap;
  295         struct g_event *ep;
  296         int error;
  297 
  298         /* g_topology_assert_not(); */
  299         va_start(ap, flag);
  300         KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
  301             ("Wrong flag to g_post_event"));
  302         error = g_post_event_x(func, arg, flag | EV_WAKEUP, &ep, ap);
  303         if (error)
  304                 return (error);
  305         do 
  306                 tsleep(ep, PRIBIO, "g_waitfor_event", hz);
  307         while (!(ep->flag & EV_DONE));
  308         if (ep->flag & EV_CANCELED)
  309                 error = EAGAIN;
  310         g_free(ep);
  311         return (error);
  312 }
  313 
  314 void
  315 g_event_init()
  316 {
  317 
  318         mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
  319         sx_init(&g_eventstall, "GEOM event stalling");
  320 }

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