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authorStephen Boyd <sboyd@codeaurora.org>2013-07-11 07:00:59 -0700
committerThomas Gleixner <tglx@linutronix.de>2013-07-12 12:35:40 +0200
commita272dcca1802a7e265a56e60b0d0a6715b0a8ac2 (patch)
tree3bc6e5294be0ff0fed757752dab4b2e4d52dde03 /kernel/time
parentf2006e27396f55276f24434f56e208d86e7f9908 (diff)
tick: broadcast: Check broadcast mode on CPU hotplug
On ARM systems the dummy clockevent is registered with the cpu hotplug notifier chain before any other per-cpu clockevent. This has the side-effect of causing the dummy clockevent to be registered first in every hotplug sequence. Because the dummy is first, we'll try to turn the broadcast source on but the code in tick_device_uses_broadcast() assumes the broadcast source is in periodic mode and calls tick_broadcast_start_periodic() unconditionally. On boot this isn't a problem because we typically haven't switched into oneshot mode yet (if at all). During hotplug, if the broadcast source isn't in periodic mode we'll replace the broadcast oneshot handler with the broadcast periodic handler and start emulating oneshot mode when we shouldn't. Due to the way the broadcast oneshot handler programs the next_event it's possible for it to contain KTIME_MAX and cause us to hang the system when the periodic handler tries to program the next tick. Fix this by using the appropriate function to start the broadcast source. Reported-by: Stephen Warren <swarren@nvidia.com> Tested-by: Stephen Warren <swarren@nvidia.com> Signed-off-by: Stephen Boyd <sboyd@codeaurora.org> Cc: Mark Rutland <Mark.Rutland@arm.com> Cc: Marc Zyngier <marc.zyngier@arm.com> Cc: ARM kernel mailing list <linux-arm-kernel@lists.infradead.org> Cc: John Stultz <john.stultz@linaro.org> Cc: Joseph Lo <josephl@nvidia.com> Link: http://lkml.kernel.org/r/20130711140059.GA27430@codeaurora.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/tick-broadcast.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 6d3f91631de..218bcb565fe 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -157,7 +157,10 @@ int tick_device_uses_broadcast(struct clock_event_device *dev, int cpu)
dev->event_handler = tick_handle_periodic;
tick_device_setup_broadcast_func(dev);
cpumask_set_cpu(cpu, tick_broadcast_mask);
- tick_broadcast_start_periodic(bc);
+ if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
+ tick_broadcast_start_periodic(bc);
+ else
+ tick_broadcast_setup_oneshot(bc);
ret = 1;
} else {
/*