9197ce2ee5
This flag gets set whenever the thread posts an event on the GEOM event queue, and if the flag is set when the thread is prepared to return to userland from the kernel, g_waitidle() will be called to make sure that the posted events have completed. This can replace an insufficient number of g_waitidle() calls in various other places, and has the advantage of being failsafe: Any system call which does a VOP_OPEN()/VOP_CLOSE will now correctly wait for any geom events it posted as part of spoils or tastes. Assert that topology and Giant is not held in g_waitidle().
350 lines
8.3 KiB
C
350 lines
8.3 KiB
C
/*-
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* Copyright (c) 2002 Poul-Henning Kamp
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* Copyright (c) 2002 Networks Associates Technology, Inc.
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* All rights reserved.
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*
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* This software was developed for the FreeBSD Project by Poul-Henning Kamp
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* and NAI Labs, the Security Research Division of Network Associates, Inc.
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* under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
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* DARPA CHATS research program.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The names of the authors may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* XXX: How do we in general know that objects referenced in events
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* have not been destroyed before we get around to handle the event ?
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <sys/param.h>
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#include <sys/malloc.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/errno.h>
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#include <sys/time.h>
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#include <geom/geom.h>
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#include <geom/geom_int.h>
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#include <machine/stdarg.h>
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TAILQ_HEAD(event_tailq_head, g_event);
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static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
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static u_int g_pending_events;
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static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
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static struct mtx g_eventlock;
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static int g_wither_work;
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#define G_N_EVENTREFS 20
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struct g_event {
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TAILQ_ENTRY(g_event) events;
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g_event_t *func;
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void *arg;
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int flag;
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void *ref[G_N_EVENTREFS];
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};
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#define EV_DONE 0x80000
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#define EV_WAKEUP 0x40000
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#define EV_CANCELED 0x20000
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void
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g_waitidle(void)
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{
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g_topology_assert_not();
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mtx_assert(&Giant, MA_NOTOWNED);
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while (g_pending_events)
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tsleep(&g_pending_events, PPAUSE, "g_waitidle", hz/5);
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curthread->td_pflags &= ~TDP_GEOM;
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}
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void
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g_orphan_provider(struct g_provider *pp, int error)
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{
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/* G_VALID_PROVIDER(pp) We likely lack topology lock */
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g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
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pp, pp->name, error);
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KASSERT(error != 0,
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("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
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pp, pp->name));
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pp->error = error;
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mtx_lock(&g_eventlock);
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KASSERT(!(pp->flags & G_PF_ORPHAN),
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("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
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pp->flags |= G_PF_ORPHAN;
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TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
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mtx_unlock(&g_eventlock);
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wakeup(&g_wait_event);
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}
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/*
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* This function is called once on each provider which the event handler
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* finds on its g_doorstep.
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*/
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static void
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g_orphan_register(struct g_provider *pp)
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{
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struct g_consumer *cp, *cp2;
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int wf;
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g_topology_assert();
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G_VALID_PROVIDER(pp);
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g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
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wf = pp->flags & G_PF_WITHER;
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pp->flags &= ~G_PF_WITHER;
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/*
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* Tell all consumers the bad news.
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* Don't be surprised if they self-destruct.
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*/
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cp = LIST_FIRST(&pp->consumers);
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while (cp != NULL) {
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cp2 = LIST_NEXT(cp, consumers);
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KASSERT(cp->geom->orphan != NULL,
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("geom %s has no orphan, class %s",
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cp->geom->name, cp->geom->class->name));
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cp->geom->orphan(cp);
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cp = cp2;
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}
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if (LIST_EMPTY(&pp->consumers) && wf)
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g_destroy_provider(pp);
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else
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pp->flags |= wf;
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#ifdef notyet
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cp = LIST_FIRST(&pp->consumers);
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if (cp != NULL)
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return;
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if (pp->geom->flags & G_GEOM_WITHER)
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g_destroy_provider(pp);
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#endif
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}
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static int
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one_event(void)
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{
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struct g_event *ep;
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struct g_provider *pp;
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g_topology_lock();
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for (;;) {
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mtx_lock(&g_eventlock);
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pp = TAILQ_FIRST(&g_doorstep);
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if (pp != NULL) {
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G_VALID_PROVIDER(pp);
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TAILQ_REMOVE(&g_doorstep, pp, orphan);
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}
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mtx_unlock(&g_eventlock);
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if (pp == NULL)
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break;
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g_orphan_register(pp);
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}
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mtx_lock(&g_eventlock);
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ep = TAILQ_FIRST(&g_events);
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if (ep == NULL) {
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mtx_unlock(&g_eventlock);
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g_topology_unlock();
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return (0);
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}
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TAILQ_REMOVE(&g_events, ep, events);
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mtx_unlock(&g_eventlock);
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g_topology_assert();
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ep->func(ep->arg, 0);
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g_topology_assert();
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if (ep->flag & EV_WAKEUP) {
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ep->flag |= EV_DONE;
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wakeup(ep);
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} else {
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g_free(ep);
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}
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g_pending_events--;
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if (g_pending_events == 0)
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wakeup(&g_pending_events);
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g_topology_unlock();
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return (1);
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}
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void
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g_run_events()
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{
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int i;
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while (one_event())
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;
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g_topology_lock();
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i = g_wither_work;
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while (i) {
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i = g_wither_washer();
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g_wither_work = i & 1;
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i &= 2;
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}
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g_topology_unlock();
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}
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void
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g_cancel_event(void *ref)
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{
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struct g_event *ep, *epn;
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struct g_provider *pp;
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u_int n;
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mtx_lock(&g_eventlock);
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TAILQ_FOREACH(pp, &g_doorstep, orphan) {
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if (pp != ref)
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continue;
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TAILQ_REMOVE(&g_doorstep, pp, orphan);
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break;
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}
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for (ep = TAILQ_FIRST(&g_events); ep != NULL; ep = epn) {
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epn = TAILQ_NEXT(ep, events);
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for (n = 0; n < G_N_EVENTREFS; n++) {
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if (ep->ref[n] == NULL)
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break;
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if (ep->ref[n] == ref) {
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TAILQ_REMOVE(&g_events, ep, events);
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ep->func(ep->arg, EV_CANCEL);
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if (ep->flag & EV_WAKEUP) {
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ep->flag |= EV_DONE;
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ep->flag |= EV_CANCELED;
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wakeup(ep);
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} else {
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g_free(ep);
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}
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if (--g_pending_events == 0)
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wakeup(&g_pending_events);
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break;
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}
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}
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}
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mtx_unlock(&g_eventlock);
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}
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static int
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g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
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{
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struct g_event *ep;
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void *p;
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u_int n;
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g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
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func, arg, flag, wakeup);
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KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
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("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
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ep = g_malloc(sizeof *ep, flag | M_ZERO);
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if (ep == NULL)
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return (ENOMEM);
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ep->flag = wuflag;
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for (n = 0; n < G_N_EVENTREFS; n++) {
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p = va_arg(ap, void *);
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if (p == NULL)
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break;
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g_trace(G_T_TOPOLOGY, " ref %p", p);
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ep->ref[n] = p;
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}
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KASSERT(p == NULL, ("Too many references to event"));
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ep->func = func;
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ep->arg = arg;
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mtx_lock(&g_eventlock);
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g_pending_events++;
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TAILQ_INSERT_TAIL(&g_events, ep, events);
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mtx_unlock(&g_eventlock);
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wakeup(&g_wait_event);
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if (epp != NULL)
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*epp = ep;
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curthread->td_pflags |= TDP_GEOM;
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return (0);
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}
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int
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g_post_event(g_event_t *func, void *arg, int flag, ...)
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{
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va_list ap;
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int i;
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KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
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("Wrong flag to g_post_event"));
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va_start(ap, flag);
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i = g_post_event_x(func, arg, flag, 0, NULL, ap);
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va_end(ap);
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return (i);
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}
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void
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g_do_wither() {
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g_wither_work = 1;
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wakeup(&g_wait_event);
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}
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/*
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* XXX: It might actually be useful to call this function with topology held.
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* XXX: This would ensure that the event gets created before anything else
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* XXX: changes. At present all users have a handle on things in some other
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* XXX: way, so this remains an XXX for now.
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*/
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int
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g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
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{
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va_list ap;
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struct g_event *ep;
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int error;
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g_topology_assert_not();
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KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
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("Wrong flag to g_post_event"));
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va_start(ap, flag);
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error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
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va_end(ap);
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if (error)
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return (error);
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do
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tsleep(ep, PRIBIO, "g_waitfor_event", hz);
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while (!(ep->flag & EV_DONE));
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if (ep->flag & EV_CANCELED)
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error = EAGAIN;
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g_free(ep);
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return (error);
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}
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void
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g_event_init()
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{
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mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
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}
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