geom_event.c

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    1 /*-
    2  * SPDX-License-Identifier: BSD-3-Clause
    3  *
    4  * Copyright (c) 2002 Poul-Henning Kamp
    5  * Copyright (c) 2002 Networks Associates Technology, Inc.
    6  * All rights reserved.
    7  *
    8  * This software was developed for the FreeBSD Project by Poul-Henning Kamp
    9  * and NAI Labs, the Security Research Division of Network Associates, Inc.
   10  * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
   11  * DARPA CHATS research program.
   12  *
   13  * Redistribution and use in source and binary forms, with or without
   14  * modification, are permitted provided that the following conditions
   15  * are met:
   16  * 1. Redistributions of source code must retain the above copyright
   17  *    notice, this list of conditions and the following disclaimer.
   18  * 2. Redistributions in binary form must reproduce the above copyright
   19  *    notice, this list of conditions and the following disclaimer in the
   20  *    documentation and/or other materials provided with the distribution.
   21  * 3. The names of the authors may not be used to endorse or promote
   22  *    products derived from this software without specific prior written
   23  *    permission.
   24  *
   25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   35  * SUCH DAMAGE.
   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/cdefs.h>
   44 __FBSDID("$FreeBSD: releng/12.0/sys/geom/geom_event.c 327430 2017-12-31 09:23:52Z cperciva $");
   45 
   46 #include <sys/param.h>
   47 #include <sys/malloc.h>
   48 #include <sys/systm.h>
   49 #include <sys/kernel.h>
   50 #include <sys/lock.h>
   51 #include <sys/mutex.h>
   52 #include <sys/proc.h>
   53 #include <sys/errno.h>
   54 #include <sys/time.h>
   55 #include <geom/geom.h>
   56 #include <geom/geom_int.h>
   57 
   58 #include <machine/stdarg.h>
   59 
   60 TAILQ_HEAD(event_tailq_head, g_event);
   61 
   62 static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
   63 static u_int g_pending_events;
   64 static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
   65 static struct mtx g_eventlock;
   66 static int g_wither_work;
   67 
   68 #define G_N_EVENTREFS           20
   69 
   70 struct g_event {
   71         TAILQ_ENTRY(g_event)    events;
   72         g_event_t               *func;
   73         void                    *arg;
   74         int                     flag;
   75         void                    *ref[G_N_EVENTREFS];
   76 };
   77 
   78 #define EV_DONE         0x80000
   79 #define EV_WAKEUP       0x40000
   80 #define EV_CANCELED     0x20000
   81 #define EV_INPROGRESS   0x10000
   82 
   83 void
   84 g_waitidle(void)
   85 {
   86 
   87         g_topology_assert_not();
   88 
   89         mtx_lock(&g_eventlock);
   90         TSWAIT("GEOM events");
   91         while (!TAILQ_EMPTY(&g_events))
   92                 msleep(&g_pending_events, &g_eventlock, PPAUSE,
   93                     "g_waitidle", hz/5);
   94         TSUNWAIT("GEOM events");
   95         mtx_unlock(&g_eventlock);
   96         curthread->td_pflags &= ~TDP_GEOM;
   97 }
   98 
   99 #if 0
  100 void
  101 g_waitidlelock(void)
  102 {
  103 
  104         g_topology_assert();
  105         mtx_lock(&g_eventlock);
  106         while (!TAILQ_EMPTY(&g_events)) {
  107                 g_topology_unlock();
  108                 msleep(&g_pending_events, &g_eventlock, PPAUSE,
  109                     "g_waitidlel", hz/5);
  110                 g_topology_lock();
  111         }
  112         mtx_unlock(&g_eventlock);
  113 }
  114 #endif
  115 
  116 struct g_attrchanged_args {
  117         struct g_provider *pp;
  118         const char *attr;
  119 };
  120 
  121 static void
  122 g_attr_changed_event(void *arg, int flag)
  123 {
  124         struct g_attrchanged_args *args;
  125         struct g_provider *pp;
  126         struct g_consumer *cp;
  127         struct g_consumer *next_cp;
  128 
  129         args = arg;
  130         pp = args->pp;
  131 
  132         g_topology_assert();
  133         if (flag != EV_CANCEL && g_shutdown == 0) {
  134 
  135                 /*
  136                  * Tell all consumers of the change.
  137                  */
  138                 LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, next_cp) {
  139                         if (cp->geom->attrchanged != NULL)
  140                                 cp->geom->attrchanged(cp, args->attr);
  141                 }
  142         }
  143         g_free(args);
  144 }
  145 
  146 int
  147 g_attr_changed(struct g_provider *pp, const char *attr, int flag)
  148 {
  149         struct g_attrchanged_args *args;
  150         int error;
  151 
  152         args = g_malloc(sizeof *args, flag);
  153         if (args == NULL)
  154                 return (ENOMEM);
  155         args->pp = pp;
  156         args->attr = attr;
  157         error = g_post_event(g_attr_changed_event, args, flag, pp, NULL);
  158         if (error != 0)
  159                 g_free(args);
  160         return (error);
  161 }
  162 
  163 void
  164 g_orphan_provider(struct g_provider *pp, int error)
  165 {
  166 
  167         /* G_VALID_PROVIDER(pp)  We likely lack topology lock */
  168         g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
  169             pp, pp->name, error);
  170         KASSERT(error != 0,
  171             ("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
  172              pp, pp->name));
  173         
  174         pp->error = error;
  175         mtx_lock(&g_eventlock);
  176         KASSERT(!(pp->flags & G_PF_ORPHAN),
  177             ("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
  178         pp->flags |= G_PF_ORPHAN;
  179         TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
  180         mtx_unlock(&g_eventlock);
  181         wakeup(&g_wait_event);
  182 }
  183 
  184 /*
  185  * This function is called once on each provider which the event handler
  186  * finds on its g_doorstep.
  187  */
  188 
  189 static void
  190 g_orphan_register(struct g_provider *pp)
  191 {
  192         struct g_consumer *cp, *cp2;
  193         int wf;
  194 
  195         g_topology_assert();
  196         G_VALID_PROVIDER(pp);
  197         g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
  198 
  199         g_cancel_event(pp);
  200 
  201         wf = pp->flags & G_PF_WITHER;
  202         pp->flags &= ~G_PF_WITHER;
  203 
  204         /*
  205          * Tell all consumers the bad news.
  206          * Don't be surprised if they self-destruct.
  207          */
  208         LIST_FOREACH_SAFE(cp, &pp->consumers, consumers, cp2) {
  209                 KASSERT(cp->geom->orphan != NULL,
  210                     ("geom %s has no orphan, class %s",
  211                     cp->geom->name, cp->geom->class->name));
  212                 /*
  213                  * XXX: g_dev_orphan method does deferred destroying
  214                  * and it is possible, that other event could already
  215                  * call the orphan method. Check consumer's flags to
  216                  * do not schedule it twice.
  217                  */
  218                 if (cp->flags & G_CF_ORPHAN)
  219                         continue;
  220                 cp->flags |= G_CF_ORPHAN;
  221                 cp->geom->orphan(cp);
  222         }
  223         if (LIST_EMPTY(&pp->consumers) && wf)
  224                 g_destroy_provider(pp);
  225         else
  226                 pp->flags |= wf;
  227 #ifdef notyet
  228         cp = LIST_FIRST(&pp->consumers);
  229         if (cp != NULL)
  230                 return;
  231         if (pp->geom->flags & G_GEOM_WITHER)
  232                 g_destroy_provider(pp);
  233 #endif
  234 }
  235 
  236 static int
  237 one_event(void)
  238 {
  239         struct g_event *ep;
  240         struct g_provider *pp;
  241 
  242         g_topology_assert();
  243         mtx_lock(&g_eventlock);
  244         TAILQ_FOREACH(pp, &g_doorstep, orphan) {
  245                 if (pp->nstart == pp->nend)
  246                         break;
  247         }
  248         if (pp != NULL) {
  249                 G_VALID_PROVIDER(pp);
  250                 TAILQ_REMOVE(&g_doorstep, pp, orphan);
  251                 mtx_unlock(&g_eventlock);
  252                 g_orphan_register(pp);
  253                 return (1);
  254         }
  255 
  256         ep = TAILQ_FIRST(&g_events);
  257         if (ep == NULL) {
  258                 wakeup(&g_pending_events);
  259                 return (0);
  260         }
  261         if (ep->flag & EV_INPROGRESS) {
  262                 mtx_unlock(&g_eventlock);
  263                 return (1);
  264         }
  265         ep->flag |= EV_INPROGRESS;
  266         mtx_unlock(&g_eventlock);
  267         g_topology_assert();
  268         ep->func(ep->arg, 0);
  269         g_topology_assert();
  270         mtx_lock(&g_eventlock);
  271         TSRELEASE("GEOM events");
  272         TAILQ_REMOVE(&g_events, ep, events);
  273         ep->flag &= ~EV_INPROGRESS;
  274         if (ep->flag & EV_WAKEUP) {
  275                 ep->flag |= EV_DONE;
  276                 mtx_unlock(&g_eventlock);
  277                 wakeup(ep);
  278         } else {
  279                 mtx_unlock(&g_eventlock);
  280                 g_free(ep);
  281         }
  282         return (1);
  283 }
  284 
  285 void
  286 g_run_events()
  287 {
  288 
  289         for (;;) {
  290                 g_topology_lock();
  291                 while (one_event())
  292                         ;
  293                 mtx_assert(&g_eventlock, MA_OWNED);
  294                 if (g_wither_work) {
  295                         g_wither_work = 0;
  296                         mtx_unlock(&g_eventlock);
  297                         g_wither_washer();
  298                         g_topology_unlock();
  299                 } else {
  300                         g_topology_unlock();
  301                         msleep(&g_wait_event, &g_eventlock, PRIBIO | PDROP,
  302                             "-", TAILQ_EMPTY(&g_doorstep) ? 0 : hz / 10);
  303                 }
  304         }
  305         /* NOTREACHED */
  306 }
  307 
  308 void
  309 g_cancel_event(void *ref)
  310 {
  311         struct g_event *ep, *epn;
  312         struct g_provider *pp;
  313         u_int n;
  314 
  315         mtx_lock(&g_eventlock);
  316         TAILQ_FOREACH(pp, &g_doorstep, orphan) {
  317                 if (pp != ref)
  318                         continue;
  319                 TAILQ_REMOVE(&g_doorstep, pp, orphan);
  320                 break;
  321         }
  322         TAILQ_FOREACH_SAFE(ep, &g_events, events, epn) {
  323                 if (ep->flag & EV_INPROGRESS)
  324                         continue;
  325                 for (n = 0; n < G_N_EVENTREFS; n++) {
  326                         if (ep->ref[n] == NULL)
  327                                 break;
  328                         if (ep->ref[n] != ref)
  329                                 continue;
  330                         TSRELEASE("GEOM events");
  331                         TAILQ_REMOVE(&g_events, ep, events);
  332                         ep->func(ep->arg, EV_CANCEL);
  333                         mtx_assert(&g_eventlock, MA_OWNED);
  334                         if (ep->flag & EV_WAKEUP) {
  335                                 ep->flag |= (EV_DONE|EV_CANCELED);
  336                                 wakeup(ep);
  337                         } else {
  338                                 g_free(ep);
  339                         }
  340                         break;
  341                 }
  342         }
  343         if (TAILQ_EMPTY(&g_events))
  344                 wakeup(&g_pending_events);
  345         mtx_unlock(&g_eventlock);
  346 }
  347 
  348 static int
  349 g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
  350 {
  351         struct g_event *ep;
  352         void *p;
  353         u_int n;
  354 
  355         g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
  356             func, arg, flag, wuflag);
  357         KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
  358             ("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
  359         ep = g_malloc(sizeof *ep, flag | M_ZERO);
  360         if (ep == NULL)
  361                 return (ENOMEM);
  362         ep->flag = wuflag;
  363         for (n = 0; n < G_N_EVENTREFS; n++) {
  364                 p = va_arg(ap, void *);
  365                 if (p == NULL)
  366                         break;
  367                 g_trace(G_T_TOPOLOGY, "  ref %p", p);
  368                 ep->ref[n] = p;
  369         }
  370         KASSERT(p == NULL, ("Too many references to event"));
  371         ep->func = func;
  372         ep->arg = arg;
  373         mtx_lock(&g_eventlock);
  374         TSHOLD("GEOM events");
  375         TAILQ_INSERT_TAIL(&g_events, ep, events);
  376         mtx_unlock(&g_eventlock);
  377         wakeup(&g_wait_event);
  378         if (epp != NULL)
  379                 *epp = ep;
  380         curthread->td_pflags |= TDP_GEOM;
  381         return (0);
  382 }
  383 
  384 int
  385 g_post_event(g_event_t *func, void *arg, int flag, ...)
  386 {
  387         va_list ap;
  388         int i;
  389 
  390         KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
  391             ("Wrong flag to g_post_event"));
  392         va_start(ap, flag);
  393         i = g_post_event_x(func, arg, flag, 0, NULL, ap);
  394         va_end(ap);
  395         return (i);
  396 }
  397 
  398 void
  399 g_do_wither()
  400 {
  401 
  402         mtx_lock(&g_eventlock);
  403         g_wither_work = 1;
  404         mtx_unlock(&g_eventlock);
  405         wakeup(&g_wait_event);
  406 }
  407 
  408 /*
  409  * XXX: It might actually be useful to call this function with topology held.
  410  * XXX: This would ensure that the event gets created before anything else
  411  * XXX: changes.  At present all users have a handle on things in some other
  412  * XXX: way, so this remains an XXX for now.
  413  */
  414 
  415 int
  416 g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
  417 {
  418         va_list ap;
  419         struct g_event *ep;
  420         int error;
  421 
  422         g_topology_assert_not();
  423         KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
  424             ("Wrong flag to g_post_event"));
  425         va_start(ap, flag);
  426         error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
  427         va_end(ap);
  428         if (error)
  429                 return (error);
  430 
  431         mtx_lock(&g_eventlock);
  432         while (!(ep->flag & EV_DONE))
  433                 msleep(ep, &g_eventlock, PRIBIO, "g_waitfor_event", hz);
  434         if (ep->flag & EV_CANCELED)
  435                 error = EAGAIN;
  436         mtx_unlock(&g_eventlock);
  437 
  438         g_free(ep);
  439         return (error);
  440 }
  441 
  442 void
  443 g_event_init()
  444 {
  445 
  446         mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
  447 }
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FreeBSD/Linux Kernel Cross Reference sys/geom/geom_event.c

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