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 
   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: releng/5.2/sys/geom/geom_event.c 124997 2004-01-26 05:18:35Z scottl $");
   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         int wf;
  130 
  131         g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
  132         g_topology_assert();
  133 
  134         wf = pp->flags & G_PF_WITHER;
  135         pp->flags &= ~G_PF_WITHER;
  136 
  137         /*
  138          * Tell all consumers the bad news.
  139          * Don't be surprised if they self-destruct.
  140          */
  141         cp = LIST_FIRST(&pp->consumers);
  142         while (cp != NULL) {
  143                 cp2 = LIST_NEXT(cp, consumers);
  144                 KASSERT(cp->geom->orphan != NULL,
  145                     ("geom %s has no orphan, class %s",
  146                     cp->geom->name, cp->geom->class->name));
  147                 cp->geom->orphan(cp);
  148                 cp = cp2;
  149         }
  150         if (LIST_EMPTY(&pp->consumers) && wf)
  151                 g_destroy_provider(pp);
  152         else
  153                 pp->flags |= wf;
  154 #ifdef notyet
  155         cp = LIST_FIRST(&pp->consumers);
  156         if (cp != NULL)
  157                 return;
  158         if (pp->geom->flags & G_GEOM_WITHER)
  159                 g_destroy_provider(pp);
  160 #endif
  161 }
  162 
  163 static int
  164 one_event(void)
  165 {
  166         struct g_event *ep;
  167         struct g_provider *pp;
  168 
  169         sx_xlock(&g_eventstall);
  170         g_topology_lock();
  171         for (;;) {
  172                 mtx_lock(&g_eventlock);
  173                 pp = TAILQ_FIRST(&g_doorstep);
  174                 if (pp != NULL)
  175                         TAILQ_REMOVE(&g_doorstep, pp, orphan);
  176                 mtx_unlock(&g_eventlock);
  177                 if (pp == NULL)
  178                         break;
  179                 g_orphan_register(pp);
  180         }
  181         mtx_lock(&g_eventlock);
  182         ep = TAILQ_FIRST(&g_events);
  183         if (ep == NULL) {
  184                 mtx_unlock(&g_eventlock);
  185                 g_topology_unlock();
  186                 sx_xunlock(&g_eventstall);
  187                 return (0);
  188         }
  189         TAILQ_REMOVE(&g_events, ep, events);
  190         mtx_unlock(&g_eventlock);
  191         g_topology_assert();
  192         ep->func(ep->arg, 0);
  193         g_topology_assert();
  194         if (ep->flag & EV_WAKEUP) {
  195                 ep->flag |= EV_DONE;
  196                 wakeup(ep);
  197         } else {
  198                 g_free(ep);
  199         }
  200         g_pending_events--;
  201         if (g_pending_events == 0)
  202                 wakeup(&g_pending_events);
  203         g_topology_unlock();
  204         sx_xunlock(&g_eventstall);
  205         return (1);
  206 }
  207 
  208 void
  209 g_run_events()
  210 {
  211 
  212         while (one_event())
  213                 ;
  214 }
  215 
  216 void
  217 g_cancel_event(void *ref)
  218 {
  219         struct g_event *ep, *epn;
  220         struct g_provider *pp;
  221         u_int n;
  222 
  223         mtx_lock(&g_eventlock);
  224         TAILQ_FOREACH(pp, &g_doorstep, orphan) {
  225                 if (pp != ref)
  226                         continue;
  227                 TAILQ_REMOVE(&g_doorstep, pp, orphan);
  228                 break;
  229         }
  230         for (ep = TAILQ_FIRST(&g_events); ep != NULL; ep = epn) {
  231                 epn = TAILQ_NEXT(ep, events);
  232                 for (n = 0; n < G_N_EVENTREFS; n++) {
  233                         if (ep->ref[n] == NULL)
  234                                 break;
  235                         if (ep->ref[n] == ref) {
  236                                 TAILQ_REMOVE(&g_events, ep, events);
  237                                 ep->func(ep->arg, EV_CANCEL);
  238                                 if (ep->flag & EV_WAKEUP) {
  239                                         ep->flag |= EV_DONE;
  240                                         ep->flag |= EV_CANCELED;
  241                                         wakeup(ep);
  242                                 } else {
  243                                         g_free(ep);
  244                                 }
  245                                 if (--g_pending_events == 0)
  246                                         wakeup(&g_pending_events);
  247                                 break;
  248                         }
  249                 }
  250         }
  251         mtx_unlock(&g_eventlock);
  252 }
  253 
  254 static int
  255 g_post_event_x(g_event_t *func, void *arg, int flag, struct g_event **epp, va_list ap)
  256 {
  257         struct g_event *ep;
  258         void *p;
  259         u_int n;
  260 
  261         g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d)", func, arg, flag);
  262         ep = g_malloc(sizeof *ep, flag | M_ZERO);
  263         if (ep == NULL)
  264                 return (ENOMEM);
  265         ep->flag = flag;
  266         for (n = 0; n < G_N_EVENTREFS; n++) {
  267                 p = va_arg(ap, void *);
  268                 if (p == NULL)
  269                         break;
  270                 g_trace(G_T_TOPOLOGY, "  ref %p", p);
  271                 ep->ref[n] = p;
  272         }
  273         KASSERT(p == NULL, ("Too many references to event"));
  274         ep->func = func;
  275         ep->arg = arg;
  276         mtx_lock(&g_eventlock);
  277         g_pending_events++;
  278         TAILQ_INSERT_TAIL(&g_events, ep, events);
  279         mtx_unlock(&g_eventlock);
  280         wakeup(&g_wait_event);
  281         if (epp != NULL)
  282                 *epp = ep;
  283         return (0);
  284 }
  285 
  286 int
  287 g_post_event(g_event_t *func, void *arg, int flag, ...)
  288 {
  289         va_list ap;
  290         int i;
  291 
  292         KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
  293             ("Wrong flag to g_post_event"));
  294         va_start(ap, flag);
  295         i = g_post_event_x(func, arg, flag, NULL, ap);
  296         va_end(ap);
  297         return (i);
  298 }
  299 
  300 
  301 /*
  302  * XXX: It might actually be useful to call this function with topology held.
  303  * XXX: This would ensure that the event gets created before anything else
  304  * XXX: changes.  At present all users have a handle on things in some other
  305  * XXX: way, so this remains an XXX for now.
  306  */
  307 
  308 int
  309 g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
  310 {
  311         va_list ap;
  312         struct g_event *ep;
  313         int error;
  314 
  315         /* g_topology_assert_not(); */
  316         KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
  317             ("Wrong flag to g_post_event"));
  318         va_start(ap, flag);
  319         error = g_post_event_x(func, arg, flag | EV_WAKEUP, &ep, ap);
  320         va_end(ap);
  321         if (error)
  322                 return (error);
  323         do 
  324                 tsleep(ep, PRIBIO, "g_waitfor_event", hz);
  325         while (!(ep->flag & EV_DONE));
  326         if (ep->flag & EV_CANCELED)
  327                 error = EAGAIN;
  328         g_free(ep);
  329         return (error);
  330 }
  331 
  332 void
  333 g_event_init()
  334 {
  335 
  336         mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
  337         sx_init(&g_eventstall, "GEOM event stalling");
  338 }
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FreeBSD/Linux Kernel Cross Reference sys/geom/geom_event.c

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