Re: [PATCH 1/3] cpuidle: coupled: disable interrupts after enteringsafe state

From: Prashant Gaikwad
Date: Thu Aug 29 2013 - 02:50:41 EST


On Saturday 24 August 2013 01:15 AM, Colin Cross wrote:
Calling cpuidle_enter_state is expected to return with interrupts
enabled, but interrupts must be disabled before starting the
ready loop synchronization stage. Call local_irq_disable after
each call to cpuidle_enter_state for the safe state.

CC: stable@xxxxxxxxxxxxxxx
Signed-off-by: Colin Cross <ccross@xxxxxxxxxxx>
---
drivers/cpuidle/coupled.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/drivers/cpuidle/coupled.c b/drivers/cpuidle/coupled.c
index 2a297f8..db92bcb 100644
--- a/drivers/cpuidle/coupled.c
+++ b/drivers/cpuidle/coupled.c
@@ -460,6 +460,7 @@ int cpuidle_enter_state_coupled(struct cpuidle_device *dev,
}
entered_state = cpuidle_enter_state(dev, drv,
dev->safe_state_index);
+ local_irq_disable();

Colin,

There is still some window where irq remains enabled after exiting safe state. It may introduce some corner case.
Instead of this can we pass a parameter to cpuidle_enter_state indicating that irq has to be enabled or not after exit from idle state, which would be false when entering safe state from coupled idle.

}
/* Read barrier ensures online_count is read after prevent is cleared */
@@ -485,6 +486,7 @@ retry:
entered_state = cpuidle_enter_state(dev, drv,
dev->safe_state_index);
+ local_irq_disable();
}
if (cpuidle_coupled_clear_pokes(dev->cpu)) {

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/