FreeBSD-5.3/sys/geom/geom_event.c
/*-
* Copyright (c) 2002 Poul-Henning Kamp
* Copyright (c) 2002 Networks Associates Technology, Inc.
* All rights reserved.
*
* This software was developed for the FreeBSD Project by Poul-Henning Kamp
* and NAI Labs, the Security Research Division of Network Associates, Inc.
* under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the
* DARPA CHATS research program.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The names of the authors may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* XXX: How do we in general know that objects referenced in events
* have not been destroyed before we get around to handle the event ?
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/sys/geom/geom_event.c,v 1.50 2004/07/08 16:17:14 phk Exp $");
#include <sys/param.h>
#include <sys/malloc.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <machine/stdarg.h>
#include <sys/errno.h>
#include <sys/time.h>
#include <geom/geom.h>
#include <geom/geom_int.h>
TAILQ_HEAD(event_tailq_head, g_event);
static struct event_tailq_head g_events = TAILQ_HEAD_INITIALIZER(g_events);
static u_int g_pending_events;
static TAILQ_HEAD(,g_provider) g_doorstep = TAILQ_HEAD_INITIALIZER(g_doorstep);
static struct mtx g_eventlock;
static int g_wither_work;
#define G_N_EVENTREFS 20
struct g_event {
TAILQ_ENTRY(g_event) events;
g_event_t *func;
void *arg;
int flag;
void *ref[G_N_EVENTREFS];
};
#define EV_DONE 0x80000
#define EV_WAKEUP 0x40000
#define EV_CANCELED 0x20000
void
g_waitidle(void)
{
while (g_pending_events)
tsleep(&g_pending_events, PPAUSE, "g_waitidle", hz/5);
}
void
g_orphan_provider(struct g_provider *pp, int error)
{
/* G_VALID_PROVIDER(pp) We likely lack topology lock */
g_trace(G_T_TOPOLOGY, "g_orphan_provider(%p(%s), %d)",
pp, pp->name, error);
KASSERT(error != 0,
("g_orphan_provider(%p(%s), 0) error must be non-zero\n",
pp, pp->name));
pp->error = error;
mtx_lock(&g_eventlock);
KASSERT(!(pp->flags & G_PF_ORPHAN),
("g_orphan_provider(%p(%s)), already an orphan", pp, pp->name));
pp->flags |= G_PF_ORPHAN;
TAILQ_INSERT_TAIL(&g_doorstep, pp, orphan);
mtx_unlock(&g_eventlock);
wakeup(&g_wait_event);
}
/*
* This function is called once on each provider which the event handler
* finds on its g_doorstep.
*/
static void
g_orphan_register(struct g_provider *pp)
{
struct g_consumer *cp, *cp2;
int wf;
g_topology_assert();
G_VALID_PROVIDER(pp);
g_trace(G_T_TOPOLOGY, "g_orphan_register(%s)", pp->name);
wf = pp->flags & G_PF_WITHER;
pp->flags &= ~G_PF_WITHER;
/*
* Tell all consumers the bad news.
* Don't be surprised if they self-destruct.
*/
cp = LIST_FIRST(&pp->consumers);
while (cp != NULL) {
cp2 = LIST_NEXT(cp, consumers);
KASSERT(cp->geom->orphan != NULL,
("geom %s has no orphan, class %s",
cp->geom->name, cp->geom->class->name));
cp->geom->orphan(cp);
cp = cp2;
}
if (LIST_EMPTY(&pp->consumers) && wf)
g_destroy_provider(pp);
else
pp->flags |= wf;
#ifdef notyet
cp = LIST_FIRST(&pp->consumers);
if (cp != NULL)
return;
if (pp->geom->flags & G_GEOM_WITHER)
g_destroy_provider(pp);
#endif
}
static int
one_event(void)
{
struct g_event *ep;
struct g_provider *pp;
g_topology_lock();
for (;;) {
mtx_lock(&g_eventlock);
pp = TAILQ_FIRST(&g_doorstep);
if (pp != NULL) {
G_VALID_PROVIDER(pp);
TAILQ_REMOVE(&g_doorstep, pp, orphan);
}
mtx_unlock(&g_eventlock);
if (pp == NULL)
break;
g_orphan_register(pp);
}
mtx_lock(&g_eventlock);
ep = TAILQ_FIRST(&g_events);
if (ep == NULL) {
mtx_unlock(&g_eventlock);
g_topology_unlock();
return (0);
}
TAILQ_REMOVE(&g_events, ep, events);
mtx_unlock(&g_eventlock);
g_topology_assert();
ep->func(ep->arg, 0);
g_topology_assert();
if (ep->flag & EV_WAKEUP) {
ep->flag |= EV_DONE;
wakeup(ep);
} else {
g_free(ep);
}
g_pending_events--;
if (g_pending_events == 0)
wakeup(&g_pending_events);
g_topology_unlock();
return (1);
}
void
g_run_events()
{
int i;
while (one_event())
;
g_topology_lock();
i = g_wither_work;
while (i) {
i = g_wither_washer();
g_wither_work = i & 1;
i &= 2;
}
g_topology_unlock();
}
void
g_cancel_event(void *ref)
{
struct g_event *ep, *epn;
struct g_provider *pp;
u_int n;
mtx_lock(&g_eventlock);
TAILQ_FOREACH(pp, &g_doorstep, orphan) {
if (pp != ref)
continue;
TAILQ_REMOVE(&g_doorstep, pp, orphan);
break;
}
for (ep = TAILQ_FIRST(&g_events); ep != NULL; ep = epn) {
epn = TAILQ_NEXT(ep, events);
for (n = 0; n < G_N_EVENTREFS; n++) {
if (ep->ref[n] == NULL)
break;
if (ep->ref[n] == ref) {
TAILQ_REMOVE(&g_events, ep, events);
ep->func(ep->arg, EV_CANCEL);
if (ep->flag & EV_WAKEUP) {
ep->flag |= EV_DONE;
ep->flag |= EV_CANCELED;
wakeup(ep);
} else {
g_free(ep);
}
if (--g_pending_events == 0)
wakeup(&g_pending_events);
break;
}
}
}
mtx_unlock(&g_eventlock);
}
static int
g_post_event_x(g_event_t *func, void *arg, int flag, int wuflag, struct g_event **epp, va_list ap)
{
struct g_event *ep;
void *p;
u_int n;
g_trace(G_T_TOPOLOGY, "g_post_event_x(%p, %p, %d, %d)",
func, arg, flag, wakeup);
KASSERT(wuflag == 0 || wuflag == EV_WAKEUP,
("Wrong wuflag in g_post_event_x(0x%x)", wuflag));
ep = g_malloc(sizeof *ep, flag | M_ZERO);
if (ep == NULL)
return (ENOMEM);
ep->flag = wuflag;
for (n = 0; n < G_N_EVENTREFS; n++) {
p = va_arg(ap, void *);
if (p == NULL)
break;
g_trace(G_T_TOPOLOGY, " ref %p", p);
ep->ref[n] = p;
}
KASSERT(p == NULL, ("Too many references to event"));
ep->func = func;
ep->arg = arg;
mtx_lock(&g_eventlock);
g_pending_events++;
TAILQ_INSERT_TAIL(&g_events, ep, events);
mtx_unlock(&g_eventlock);
wakeup(&g_wait_event);
if (epp != NULL)
*epp = ep;
return (0);
}
int
g_post_event(g_event_t *func, void *arg, int flag, ...)
{
va_list ap;
int i;
KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
("Wrong flag to g_post_event"));
va_start(ap, flag);
i = g_post_event_x(func, arg, flag, 0, NULL, ap);
va_end(ap);
return (i);
}
void
g_do_wither() {
g_wither_work = 1;
wakeup(&g_wait_event);
}
/*
* XXX: It might actually be useful to call this function with topology held.
* XXX: This would ensure that the event gets created before anything else
* XXX: changes. At present all users have a handle on things in some other
* XXX: way, so this remains an XXX for now.
*/
int
g_waitfor_event(g_event_t *func, void *arg, int flag, ...)
{
va_list ap;
struct g_event *ep;
int error;
g_topology_assert_not();
KASSERT(flag == M_WAITOK || flag == M_NOWAIT,
("Wrong flag to g_post_event"));
va_start(ap, flag);
error = g_post_event_x(func, arg, flag, EV_WAKEUP, &ep, ap);
va_end(ap);
if (error)
return (error);
do
tsleep(ep, PRIBIO, "g_waitfor_event", hz);
while (!(ep->flag & EV_DONE));
if (ep->flag & EV_CANCELED)
error = EAGAIN;
g_free(ep);
return (error);
}
void
g_event_init()
{
mtx_init(&g_eventlock, "GEOM orphanage", NULL, MTX_DEF);
}