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 
   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/10.0/sys/geom/geom_event.c 248674 2013-03-24 03:15:20Z mav $");
   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 #define EV_INPROGRESS   0x10000
   80 
   81 void
   82 g_waitidle(void)
   83 {
   84 
   85         g_topology_assert_not();
   86         mtx_assert(&Giant, MA_NOTOWNED);
   87 
   88         mtx_lock(&g_eventlock);
   89         while (!TAILQ_EMPTY(&g_events))
   90                 msleep(&g_pending_events, &g_eventlock, PPAUSE,
   91                     "g_waitidle", hz/5);
   92         mtx_unlock(&g_eventlock);
   93         curthread->td_pflags &= ~TDP_GEOM;
   94 }
   95 
   96 #if 0
   97 void
   98 g_waitidlelock(void)
   99 {
  100 
  101         g_topology_assert();
  102         mtx_lock(&g_eventlock);
  103         while (!TAILQ_EMPTY(&g_events)) {
  104                 g_topology_unlock();
  105                 msleep(&g_pending_events, &g_eventlock, PPAUSE,
  106                     "g_waitidlel", hz/5);
  107                 g_topology_lock();
  108         }
  109         mtx_unlock(&g_eventlock);
  110 }
  111 #endif
  112 
  113 struct g_attrchanged_args {
  114         struct g_provider *pp;
  115         const char *attr;
  116 };
  117 
  118 static void
  119 g_attr_changed_event(void *arg, int flag)
  120 {
  121         struct g_attrchanged_args *args;
  122         struct g_provider *pp;
  123         struct g_consumer *cp;
  124         struct g_consumer *next_cp;
  125 
  126         args = arg;
  127         pp = args->pp;
  128 
  129         g_topology_assert();
  130         if (flag != EV_CANCEL && g_shutdown == 0) {
  131 
  132                 /*
  133                  * Tell all consumers of the change.
  134                  */
  135                 LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, next_cp) {
  136                         if (cp->geom->attrchanged != NULL)
  137                                 cp->geom->attrchanged(cp, args->attr);
  138                 }
  139         }
  140         g_free(args);
  141 }
  142 
  143 int
  144 g_attr_changed(struct g_provider *pp, const char *attr, int flag)
  145 {
  146         struct g_attrchanged_args *args;
  147         int error;
  148 
  149         args = g_malloc(sizeof *args, flag);
  150         if (args == NULL)
  151                 return (ENOMEM);
  152         args->pp = pp;
  153         args->attr = attr;
  154         error = g_post_event(g_attr_changed_event, args, flag, pp, NULL);
  155         if (error != 0)
  156                 g_free(args);
  157         return (error);
  158 }
  159 
  160 void
  161 g_orphan_provider(struct g_provider *pp, int error)
  162 {
  163 
  164         /* G_VALID_PROVIDER(pp)  We likely lack topology lock */
  165         g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
  166             pp, pp->name, error);
  167         KASSERT(error != 0,
  168             ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
  169              pp, pp->name));
  170         
  171         pp->error = error;
  172         mtx_lock(&g_eventlock);
  173         KASSERT(!(pp->flags & G_PF_ORPHAN),
  174             ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
  175         pp->flags |= G_PF_ORPHAN;
  176         TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
  177         mtx_unlock(&g_eventlock);
  178         wakeup(&g_wait_event);
  179 }
  180 
  181 /*
  182  * This function is called once on each provider which the event handler
  183  * finds on its g_doorstep.
  184  */
  185 
  186 static void
  187 g_orphan_register(struct g_provider *pp)
  188 {
  189         struct g_consumer *cp, *cp2;
  190         int wf;
  191 
  192         g_topology_assert();
  193         G_VALID_PROVIDER(pp);
  194         g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
  195 
  196         g_cancel_event(pp);
  197 
  198         wf = pp->flags & G_PF_WITHER;
  199         pp->flags &= ~G_PF_WITHER;
  200 
  201         /*
  202          * Tell all consumers the bad news.
  203          * Don't be surprised if they self-destruct.
  204          */
  205         LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, cp2) {
  206                 KASSERT(cp->geom->orphan != NULL,
  207                     ("geom %s has no orphan, class %s",
  208                     cp->geom->name, cp->geom->class->name));
  209                 cp->flags |= G_CF_ORPHAN;
  210                 cp->geom->orphan(cp);
  211         }
  212         if (LIST_EMPTY(&pp->consumers) && wf)
  213                 g_destroy_provider(pp);
  214         else
  215                 pp->flags |= wf;
  216 #ifdef notyet
  217         cp = LIST_FIRST(&pp->consumers);
  218         if (cp != NULL)
  219                 return;
  220         if (pp->geom->flags & G_GEOM_WITHER)
  221                 g_destroy_provider(pp);
  222 #endif
  223 }
  224 
  225 static int
  226 one_event(void)
  227 {
  228         struct g_event *ep;
  229         struct g_provider *pp;
  230 
  231         g_topology_assert();
  232         mtx_lock(&g_eventlock);
  233         TAILQ_FOREACH(pp, &g_doorstep, orphan) {
  234                 if (pp->nstart == pp->nend)
  235                         break;
  236         }
  237         if (pp != NULL) {
  238                 G_VALID_PROVIDER(pp);
  239                 TAILQ_REMOVE(&g_doorstep, pp, orphan);
  240                 mtx_unlock(&g_eventlock);
  241                 g_orphan_register(pp);
  242                 return (1);
  243         }
  244 
  245         ep = TAILQ_FIRST(&g_events);
  246         if (ep == NULL) {
  247                 wakeup(&g_pending_events);
  248                 return (0);
  249         }
  250         if (ep->flag & EV_INPROGRESS) {
  251                 mtx_unlock(&g_eventlock);
  252                 return (1);
  253         }
  254         ep->flag |= EV_INPROGRESS;
  255         mtx_unlock(&g_eventlock);
  256         g_topology_assert();
  257         ep->func(ep->arg, 0);
  258         g_topology_assert();
  259         mtx_lock(&g_eventlock);
  260         TAILQ_REMOVE(&g_events, ep, events);
  261         ep->flag &= ~EV_INPROGRESS;
  262         if (ep->flag & EV_WAKEUP) {
  263                 ep->flag |= EV_DONE;
  264                 mtx_unlock(&g_eventlock);
  265                 wakeup(ep);
  266         } else {
  267                 mtx_unlock(&g_eventlock);
  268                 g_free(ep);
  269         }
  270         return (1);
  271 }
  272 
  273 void
  274 g_run_events()
  275 {
  276 
  277         for (;;) {
  278                 g_topology_lock();
  279                 while (one_event())
  280                         ;
  281                 mtx_assert(&g_eventlock, MA_OWNED);
  282                 if (g_wither_work) {
  283                         g_wither_work = 0;
  284                         mtx_unlock(&g_eventlock);
  285                         g_wither_washer();
  286                         g_topology_unlock();
  287                 } else {
  288                         g_topology_unlock();
  289                         msleep(&g_wait_event, &g_eventlock, PRIBIO | PDROP,
  290                             "-", TAILQ_EMPTY(&g_doorstep) ? 0 : hz / 10);
  291                 }
  292         }
  293         /* NOTREACHED */
  294 }
  295 
  296 void
  297 g_cancel_event(void *ref)
  298 {
  299         struct g_event *ep, *epn;
  300         struct g_provider *pp;
  301         u_int n;
  302 
  303         mtx_lock(&g_eventlock);
  304         TAILQ_FOREACH(pp, &g_doorstep, orphan) {
  305                 if (pp != ref)
  306                         continue;
  307                 TAILQ_REMOVE(&g_doorstep, pp, orphan);
  308                 break;
  309         }
  310         TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
  311                 if (ep->flag & EV_INPROGRESS)
  312                         continue;
  313                 for (n = 0; n < G_N_EVENTREFS; n++) {
  314                         if (ep->ref[n] == NULL)
  315                                 break;
  316                         if (ep->ref[n] != ref)
  317                                 continue;
  318                         TAILQ_REMOVE(&g_events, ep, events);
  319                         ep->func(ep->arg, EV_CANCEL);
  320                         mtx_assert(&g_eventlock, MA_OWNED);
  321                         if (ep->flag & EV_WAKEUP) {
  322                                 ep->flag |= (EV_DONE|EV_CANCELED);
  323                                 wakeup(ep);
  324                         } else {
  325                                 g_free(ep);
  326                         }
  327                         break;
  328                 }
  329         }
  330         if (TAILQ_EMPTY(&g_events))
  331                 wakeup(&g_pending_events);
  332         mtx_unlock(&g_eventlock);
  333 }
  334 
  335 static int
  336 g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
  337 {
  338         struct g_event *ep;
  339         void *p;
  340         u_int n;
  341 
  342         g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
  343             func, arg, flag, wuflag);
  344         KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
  345             ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
  346         ep = g_malloc(sizeof *ep, flag | M_ZERO);
  347         if (ep == NULL)
  348                 return (ENOMEM);
  349         ep->flag = wuflag;
  350         for (n = 0; n < G_N_EVENTREFS; n++) {
  351                 p = va_arg(ap, void *);
  352                 if (p == NULL)
  353                         break;
  354                 g_trace(G_T_TOPOLOGY, "  ref %p", p);
  355                 ep->ref[n] = p;
  356         }
  357         KASSERT(p == NULL, ("Too many references to event"));
  358         ep->func = func;
  359         ep->arg = arg;
  360         mtx_lock(&g_eventlock);
  361         TAILQ_INSERT_TAIL(&g_events, ep, events);
  362         mtx_unlock(&g_eventlock);
  363         wakeup(&g_wait_event);
  364         if (epp != NULL)
  365                 *epp = ep;
  366         curthread->td_pflags |= TDP_GEOM;
  367         return (0);
  368 }
  369 
  370 int
  371 g_post_event(g_event_t *func, void *arg, int flag, ...)
  372 {
  373         va_list ap;
  374         int i;
  375 
  376         KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
  377             ("Wrong flag to g_post_event"));
  378         va_start(ap, flag);
  379         i = g_post_event_x(func, arg, flag, 0, NULL, ap);
  380         va_end(ap);
  381         return (i);
  382 }
  383 
  384 void
  385 g_do_wither()
  386 {
  387 
  388         mtx_lock(&g_eventlock);
  389         g_wither_work = 1;
  390         mtx_unlock(&g_eventlock);
  391         wakeup(&g_wait_event);
  392 }
  393 
  394 /*
  395  * XXX: It might actually be useful to call this function with topology held.
  396  * XXX: This would ensure that the event gets created before anything else
  397  * XXX: changes.  At present all users have a handle on things in some other
  398  * XXX: way, so this remains an XXX for now.
  399  */
  400 
  401 int
  402 g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
  403 {
  404         va_list ap;
  405         struct g_event *ep;
  406         int error;
  407 
  408         g_topology_assert_not();
  409         KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
  410             ("Wrong flag to g_post_event"));
  411         va_start(ap, flag);
  412         error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
  413         va_end(ap);
  414         if (error)
  415                 return (error);
  416 
  417         mtx_lock(&g_eventlock);
  418         while (!(ep->flag & EV_DONE))
  419                 msleep(ep, &g_eventlock, PRIBIO, "g_waitfor_event", hz);
  420         if (ep->flag & EV_CANCELED)
  421                 error = EAGAIN;
  422         mtx_unlock(&g_eventlock);
  423 
  424         g_free(ep);
  425         return (error);
  426 }
  427 
  428 void
  429 g_event_init()
  430 {
  431 
  432         mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
  433 }

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