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Commit e0454311 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

tick/broadcast: Sanity check the shutdown of the local clock_event 



The broadcast code shuts down the local clock event unconditionally
even if no broadcast device is installed or if the broadcast device is
hrtimer based.

Add proper sanity checks.

[ Split out from a larger combo patch ]

Reported-and-tested-by: default avatarSudeep Holla <sudeep.holla@arm.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Suzuki Poulose <Suzuki.Poulose@arm.com>
Cc: Lorenzo Pieralisi <Lorenzo.Pieralisi@arm.com>
Cc: Catalin Marinas <Catalin.Marinas@arm.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1507070929360.3916@nanos
parent 8eb23126

kernel/time/tick-broadcast.c

+16 −7
Original line number Diff line number Diff line
@@ -159,7 +159,7 @@ int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu) 
{

	struct clock_event_device *bc = tick_broadcast_device.evtdev;

	unsigned long flags;

	int ret;

	int ret = 0;



	raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
@@ -221,13 +221,14 @@ int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu) 
			 * If we kept the cpu in the broadcast mask,

			 * tell the caller to leave the per cpu device

			 * in shutdown state. The periodic interrupt

			 * is delivered by the broadcast device.

			 * is delivered by the broadcast device, if

			 * the broadcast device exists and is not

			 * hrtimer based.

			 */

			if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER))

				ret = cpumask_test_cpu(cpu, tick_broadcast_mask);

			break;

		default:

			/* Nothing to do */

			ret = 0;

			break;

		}

	}
@@ -373,8 +374,16 @@ void tick_broadcast_control(enum tick_broadcast_mode mode) 
	case TICK_BROADCAST_ON:

		cpumask_set_cpu(cpu, tick_broadcast_on);

		if (!cpumask_test_and_set_cpu(cpu, tick_broadcast_mask)) {

			if (tick_broadcast_device.mode ==

			    TICKDEV_MODE_PERIODIC)

			/*

			 * Only shutdown the cpu local device, if:

			 *

			 * - the broadcast device exists

			 * - the broadcast device is not a hrtimer based one

			 * - the broadcast device is in periodic mode to

			 *   avoid a hickup during switch to oneshot mode

			 */

			if (bc && !(bc->features & CLOCK_EVT_FEAT_HRTIMER) &&

			    tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)

				clockevents_shutdown(dev);

		}

		break;