clockevents: Don't allow dummy broadcast timers

Currently tick_check_broadcast_device doesn't reject clock_event_devices with CLOCK_EVT_FEAT_DUMMY, and may select them in preference to real hardware if they have a higher rating value. In this situation, the dummy timer is responsible for broadcasting to itself, and the core clockevents code may attempt to call non-existent callbacks for programming the dummy, eventually leading to a panic. This patch makes tick_check_broadcast_device always reject dummy timers, preventing this problem. Signed-off-by: Mark Rutland <[email protected]> Cc: [email protected] Cc: Jon Medhurst (Tixy) <[email protected]> Cc: [email protected] Signed-off-by: Thomas Gleixner <[email protected]>
Red54 · Mar 7, 2013 · a7dc19b · a7dc19b
1 parent 6dbe51c
commit a7dc19b
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
@@ -67,7 +67,8 @@ static void tick_broadcast_start_periodic(struct clock_event_device *bc)
  */
 int tick_check_broadcast_device(struct clock_event_device *dev)
 {
-	if ((tick_broadcast_device.evtdev &&
+	if ((dev->features & CLOCK_EVT_FEAT_DUMMY) ||
+	    (tick_broadcast_device.evtdev &&
 	     tick_broadcast_device.evtdev->rating >= dev->rating) ||
 	     (dev->features & CLOCK_EVT_FEAT_C3STOP))
 		return 0;