Author: jh
Date: Mon Nov 22 16:47:53 2010
New Revision: 215687
URL: http://svn.freebsd.org/changeset/base/215687
Log:
Use g_eventlock to protect against losing wakeups in the g_event process
and replace tsleep(9) with msleep(9) which doesn't use a timeout. The
previously used timeout caused the event process to wake up ten times
per second on an idle system.
one_event() is now called with the topology lock held and it returns
with both the topology and event locks held when there are no more
events in the queue.
Reported by: mav, Marius Nünnerich
Reviewed by: freebsd-geom
Modified:
head/sys/geom/geom_event.c
head/sys/geom/geom_kern.c
Modified: head/sys/geom/geom_event.c
==============================================================================
--- head/sys/geom/geom_event.c Mon Nov 22 16:43:05 2010 (r215686)
+++ head/sys/geom/geom_event.c Mon Nov 22 16:47:53 2010 (r215687)
@@ -183,33 +183,27 @@ one_event(void)
struct g_event *ep;
struct g_provider *pp;
- g_topology_lock();
- for (;;) {
- mtx_lock(&g_eventlock);
- TAILQ_FOREACH(pp, &g_doorstep, orphan) {
- if (pp->nstart == pp->nend)
- break;
- }
- if (pp != NULL) {
- G_VALID_PROVIDER(pp);
- TAILQ_REMOVE(&g_doorstep, pp, orphan);
- }
- mtx_unlock(&g_eventlock);
- if (pp == NULL)
+ g_topology_assert();
+ mtx_lock(&g_eventlock);
+ TAILQ_FOREACH(pp, &g_doorstep, orphan) {
+ if (pp->nstart == pp->nend)
break;
+ }
+ if (pp != NULL) {
+ G_VALID_PROVIDER(pp);
+ TAILQ_REMOVE(&g_doorstep, pp, orphan);
+ mtx_unlock(&g_eventlock);
g_orphan_register(pp);
+ return (1);
}
- mtx_lock(&g_eventlock);
+
ep = TAILQ_FIRST(&g_events);
if (ep == NULL) {
wakeup(&g_pending_events);
- mtx_unlock(&g_eventlock);
- g_topology_unlock();
return (0);
}
if (ep->flag & EV_INPROGRESS) {
mtx_unlock(&g_eventlock);
- g_topology_unlock();
return (1);
}
ep->flag |= EV_INPROGRESS;
@@ -228,7 +222,6 @@ one_event(void)
mtx_unlock(&g_eventlock);
g_free(ep);
}
- g_topology_unlock();
return (1);
}
@@ -237,16 +230,27 @@ 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;
+ for (;;) {
+ g_topology_lock();
+ while (one_event())
+ ;
+ mtx_assert(&g_eventlock, MA_OWNED);
+ i = g_wither_work;
+ if (i) {
+ mtx_unlock(&g_eventlock);
+ while (i) {
+ i = g_wither_washer();
+ g_wither_work = i & 1;
+ i &= 2;
+ }
+ g_topology_unlock();
+ } else {
+ g_topology_unlock();
+ msleep(&g_wait_event, &g_eventlock, PRIBIO | PDROP,
+ "-", 0);
+ }
}
- g_topology_unlock();
+ /* NOTREACHED */
}
void
@@ -338,9 +342,12 @@ g_post_event(g_event_t *func, void *arg,
}
void
-g_do_wither() {
+g_do_wither()
+{
+ mtx_lock(&g_eventlock);
g_wither_work = 1;
+ mtx_unlock(&g_eventlock);
wakeup(&g_wait_event);
}
Modified: head/sys/geom/geom_kern.c
==============================================================================
--- head/sys/geom/geom_kern.c Mon Nov 22 16:43:05 2010 (r215686)
+++ head/sys/geom/geom_kern.c Mon Nov 22 16:47:53 2010 (r215687)
@@ -137,10 +137,8 @@ g_event_procbody(void)
thread_lock(tp);
sched_prio(tp, PRIBIO);
thread_unlock(tp);
- for(;;) {
- g_run_events();
- tsleep(&g_wait_event, PRIBIO, "-", hz/10);
- }
+ g_run_events();
+ /* NOTREACHED */
}
static struct kproc_desc g_event_kp = {
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