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/6.0/sys/geom/geom_event.c 151064 2005-10-07 15:06:27Z phk $");
   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         wf = pp->flags & G_PF_WITHER;
  149         pp->flags &= ~G_PF_WITHER;
  150 
  151         /*
  152          * Tell all consumers the bad news.
  153          * Don't be surprised if they self-destruct.
  154          */
  155         cp = LIST_FIRST(&pp->consumers);
  156         while (cp != NULL) {
  157                 cp2 = LIST_NEXT(cp, consumers);
  158                 KASSERT(cp->geom->orphan != NULL,
  159                     ("geom %s has no orphan, class %s",
  160                     cp->geom->name, cp->geom->class->name));
  161                 cp->geom->orphan(cp);
  162                 cp = cp2;
  163         }
  164         if (LIST_EMPTY(&pp->consumers) && wf)
  165                 g_destroy_provider(pp);
  166         else
  167                 pp->flags |= wf;
  168 #ifdef notyet
  169         cp = LIST_FIRST(&pp->consumers);
  170         if (cp != NULL)
  171                 return;
  172         if (pp->geom->flags & G_GEOM_WITHER)
  173                 g_destroy_provider(pp);
  174 #endif
  175 }
  176 
  177 static int
  178 one_event(void)
  179 {
  180         struct g_event *ep;
  181         struct g_provider *pp;
  182 
  183         g_topology_lock();
  184         for (;;) {
  185                 mtx_lock(&g_eventlock);
  186                 pp = TAILQ_FIRST(&g_doorstep);
  187                 if (pp != NULL) {
  188                         G_VALID_PROVIDER(pp);
  189                         TAILQ_REMOVE(&g_doorstep, pp, orphan);
  190                 }
  191                 mtx_unlock(&g_eventlock);
  192                 if (pp == NULL)
  193                         break;
  194                 g_orphan_register(pp);
  195         }
  196         mtx_lock(&g_eventlock);
  197         ep = TAILQ_FIRST(&g_events);
  198         if (ep == NULL) {
  199                 wakeup(&g_pending_events);
  200                 mtx_unlock(&g_eventlock);
  201                 g_topology_unlock();
  202                 return (0);
  203         }
  204         mtx_unlock(&g_eventlock);
  205         g_topology_assert();
  206         ep->func(ep->arg, 0);
  207         g_topology_assert();
  208         mtx_lock(&g_eventlock);
  209         TAILQ_REMOVE(&g_events, ep, events);
  210         mtx_unlock(&g_eventlock);
  211         if (ep->flag & EV_WAKEUP) {
  212                 ep->flag |= EV_DONE;
  213                 wakeup(ep);
  214         } else {
  215                 g_free(ep);
  216         }
  217         g_topology_unlock();
  218         return (1);
  219 }
  220 
  221 void
  222 g_run_events()
  223 {
  224         int i;
  225 
  226         while (one_event())
  227                 ;
  228         g_topology_lock();
  229         i = g_wither_work;
  230         while (i) {
  231                 i = g_wither_washer();
  232                 g_wither_work = i & 1;
  233                 i &= 2;
  234         }
  235         g_topology_unlock();
  236 }
  237 
  238 void
  239 g_cancel_event(void *ref)
  240 {
  241         struct g_event *ep, *epn;
  242         struct g_provider *pp;
  243         u_int n;
  244 
  245         mtx_lock(&g_eventlock);
  246         TAILQ_FOREACH(pp, &g_doorstep, orphan) {
  247                 if (pp != ref)
  248                         continue;
  249                 TAILQ_REMOVE(&g_doorstep, pp, orphan);
  250                 break;
  251         }
  252         TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
  253                 for (n = 0; n < G_N_EVENTREFS; n++) {
  254                         if (ep->ref[n] == NULL)
  255                                 break;
  256                         if (ep->ref[n] != ref)
  257                                 continue;
  258                         TAILQ_REMOVE(&g_events, ep, events);
  259                         ep->func(ep->arg, EV_CANCEL);
  260                         mtx_assert(&g_eventlock, MA_OWNED);
  261                         if (ep->flag & EV_WAKEUP) {
  262                                 ep->flag |= (EV_DONE|EV_CANCELED);
  263                                 wakeup(ep);
  264                         } else {
  265                                 g_free(ep);
  266                         }
  267                         break;
  268                 }
  269         }
  270         if (TAILQ_EMPTY(&g_events))
  271                 wakeup(&g_pending_events);
  272         mtx_unlock(&g_eventlock);
  273 }
  274 
  275 static int
  276 g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
  277 {
  278         struct g_event *ep;
  279         void *p;
  280         u_int n;
  281 
  282         g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
  283             func, arg, flag, wuflag);
  284         KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
  285             ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
  286         ep = g_malloc(sizeof *ep, flag | M_ZERO);
  287         if (ep == NULL)
  288                 return (ENOMEM);
  289         ep->flag = wuflag;
  290         for (n = 0; n < G_N_EVENTREFS; n++) {
  291                 p = va_arg(ap, void *);
  292                 if (p == NULL)
  293                         break;
  294                 g_trace(G_T_TOPOLOGY, "  ref %p", p);
  295                 ep->ref[n] = p;
  296         }
  297         KASSERT(p == NULL, ("Too many references to event"));
  298         ep->func = func;
  299         ep->arg = arg;
  300         mtx_lock(&g_eventlock);
  301         TAILQ_INSERT_TAIL(&g_events, ep, events);
  302         mtx_unlock(&g_eventlock);
  303         wakeup(&g_wait_event);
  304         if (epp != NULL)
  305                 *epp = ep;
  306         curthread->td_pflags |= TDP_GEOM;
  307         return (0);
  308 }
  309 
  310 int
  311 g_post_event(g_event_t *func, void *arg, int flag, ...)
  312 {
  313         va_list ap;
  314         int i;
  315 
  316         KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
  317             ("Wrong flag to g_post_event"));
  318         va_start(ap, flag);
  319         i = g_post_event_x(func, arg, flag, 0, NULL, ap);
  320         va_end(ap);
  321         return (i);
  322 }
  323 
  324 void
  325 g_do_wither() {
  326 
  327         g_wither_work = 1;
  328         wakeup(&g_wait_event);
  329 }
  330 
  331 /*
  332  * XXX: It might actually be useful to call this function with topology held.
  333  * XXX: This would ensure that the event gets created before anything else
  334  * XXX: changes.  At present all users have a handle on things in some other
  335  * XXX: way, so this remains an XXX for now.
  336  */
  337 
  338 int
  339 g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
  340 {
  341         va_list ap;
  342         struct g_event *ep;
  343         int error;
  344 
  345         g_topology_assert_not();
  346         KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
  347             ("Wrong flag to g_post_event"));
  348         va_start(ap, flag);
  349         error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
  350         va_end(ap);
  351         if (error)
  352                 return (error);
  353         do 
  354                 tsleep(ep, PRIBIO, "g_waitfor_event", hz);
  355         while (!(ep->flag & EV_DONE));
  356         if (ep->flag & EV_CANCELED)
  357                 error = EAGAIN;
  358         g_free(ep);
  359         return (error);
  360 }
  361 
  362 void
  363 g_event_init()
  364 {
  365 
  366         mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
  367 }
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FreeBSD/Linux Kernel Cross Reference sys/geom/geom_event.c

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