cpuidle: always return with interrupts enabled

In the case where cpuidle_idle_call() returns before changing state due to
a need_resched(), it was returning with IRQs disabled.

The idle path assumes that the platform specific idle code returns with
interrupts enabled (although this too is undocumented AFAICT) and on ARM
we have a WARN_ON(!(irqs_disabled()) when returning from the idle loop, so
the user-visible effects were only a warning since interrupts were
eventually re-enabled later.

On x86, this same problem exists, but there is no WARN_ON() to detect it.
As on ARM, the interrupts are eventually re-enabled, so I'm not sure of
any actual bugs triggered by this.  It's primarily a
correctness/consistency fix.

This patch ensures IRQs are (re)enabled before returning.

Reported-by: Hemanth V <[email protected]>
Signed-off-by: Kevin Hilman <[email protected]>
Cc: Arjan van de Ven <[email protected]>
Cc: Len Brown <[email protected]>
Cc: Venkatesh Pallipadi <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "Rafael J. Wysocki" <[email protected]>
Tested-by: Martin Michlmayr <[email protected]>
Cc: <[email protected]>		[2.6.31.x]
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index ad41f19b8e3fa22d008a4c1e3c1ce9ec79fa025e..12fdd3987a36c2b09ab65b9d598f276e51fbf5b7 100644 (file)
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -76,8 +76,11 @@ static void cpuidle_idle_call(void)
 #endif
        /* ask the governor for the next state */
        next_state = cpuidle_curr_governor->select(dev);
-       if (need_resched())
+       if (need_resched()) {
+               local_irq_enable();
                return;
+       }
+
        target_state = &dev->states[next_state];
 
        /* enter the state and update stats */