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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: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Thomas 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
hifive-unleashed-5.1
Thomas Gleixner 2015-07-07 14:07:27 +02:00
parent 8eb231261f
commit e045431190
1 changed files with 16 additions and 7 deletions
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23
kernel/time/tick-broadcast.c
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@ -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.
*/
ret = cpumask_test_cpu(cpu, tick_broadcast_mask);
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;