Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a7dc19b8 authored by Mark Rutland's avatar Mark Rutland Committed by Thomas Gleixner
Browse files

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: default avatarMark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Jon Medhurst (Tixy) <tixy@linaro.org>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 6dbe51c2

kernel/time/tick-broadcast.c

+2 −1
Original line number Diff line number Diff line
@@ -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;