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From: Jaakko Heinonen <jh@FreeBSD.org>
Date: Wed, 3 Nov 2010 16:19:35 +0000 (UTC)
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Subject: svn commit: r214748 - head/sys/geom
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Author: jh
Date: Wed Nov  3 16:19:35 2010
New Revision: 214748
URL: http://svn.freebsd.org/changeset/base/214748

Log:
  Extend the g_eventlock mutex coverage in one_event() to include setting
  of the EV_DONE flag and use the mutex to protect against losing wakeups
  in g_waitfor_event().
  
  Reported by:	davidxu
  Tested by:	davidxu
  Discussed on:	freebsd-current

Modified:
  head/sys/geom/geom_event.c

Modified: head/sys/geom/geom_event.c
==============================================================================
--- head/sys/geom/geom_event.c	Wed Nov  3 15:54:50 2010	(r214747)
+++ head/sys/geom/geom_event.c	Wed Nov  3 16:19:35 2010	(r214748)
@@ -220,11 +220,12 @@ one_event(void)
 	mtx_lock(&g_eventlock);
 	TAILQ_REMOVE(&g_events, ep, events);
 	ep->flag &= ~EV_INPROGRESS;
-	mtx_unlock(&g_eventlock);
 	if (ep->flag & EV_WAKEUP) {
 		ep->flag |= EV_DONE;
+		mtx_unlock(&g_eventlock);
 		wakeup(ep);
 	} else {
+		mtx_unlock(&g_eventlock);
 		g_free(ep);
 	}
 	g_topology_unlock();
@@ -365,11 +366,14 @@ g_waitfor_event(g_event_t *func, void *a
 	va_end(ap);
 	if (error)
 		return (error);
-	do 
-		tsleep(ep, PRIBIO, "g_waitfor_event", hz);
-	while (!(ep->flag & EV_DONE));
+
+	mtx_lock(&g_eventlock);
+	while (!(ep->flag & EV_DONE))
+		msleep(ep, &g_eventlock, PRIBIO, "g_waitfor_event", hz);
 	if (ep->flag & EV_CANCELED)
 		error = EAGAIN;
+	mtx_unlock(&g_eventlock);
+
 	g_free(ep);
 	return (error);
 }