commit 9cc712efc708bf2d25b6a6c013c66c42f2cfccd0
author José Adolfo Galdámez <josegalre@pac-rom.com> Wed Oct 21 21:52:13 2015 -0600
committer William Bellavance <flintman@flintmancomputers.com> Wed Feb 10 20:04:59 2016 -0500
tree f4b7b9d2354b77f6a63eacded1c5b32282c18abc
parent 64c363146fe8b4b26285d36fad0fc01b9c8c1285

Merge tag 'v3.4.110' into mm-6.0

Change-Id: I0afc69bce474139d1b70e062d72c0b8054529833
Signed-off-by: José Adolfo Galdámez <josegalre@pac-rom.com>

kernel/hrtimer.c

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 3c9ca94..db4dc6b 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -854,6 +854,9 @@
 	if (delta.tv64 < 0)
 		return 0;
 
+	if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
+		return 0;
+
 	if (interval.tv64 < timer->base->resolution.tv64)
 		interval.tv64 = timer->base->resolution.tv64;
 
@@ -1266,11 +1269,14 @@
 	 * Note: We clear the CALLBACK bit after enqueue_hrtimer and
 	 * we do not reprogramm the event hardware. Happens either in
 	 * hrtimer_start_range_ns() or in hrtimer_interrupt()
+	 *
+	 * Note: Because we dropped the cpu_base->lock above,
+	 * hrtimer_start_range_ns() can have popped in and enqueued the timer
+	 * for us already.
 	 */
-	if (restart != HRTIMER_NORESTART) {
-		BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
+	if (restart != HRTIMER_NORESTART &&
+	    !(timer->state & HRTIMER_STATE_ENQUEUED))
 		enqueue_hrtimer(timer, base);
-	}
 
 	WARN_ON_ONCE(!(timer->state & HRTIMER_STATE_CALLBACK));