The following commit has been merged in the linux branch: commit 246eb7f0ed1a8aeddec5313137767658f378949b Author: Kevin Hilman khilman@deeprootsystems.com Date: Mon Oct 26 16:50:18 2009 -0700

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 hemanthv@ti.com Signed-off-by: Kevin Hilman khilman@deeprootsystems.com Cc: Arjan van de Ven arjan@linux.intel.com Cc: Len Brown len.brown@intel.com Cc: Venkatesh Pallipadi venkatesh.pallipadi@intel.com Cc: Ingo Molnar mingo@elte.hu Cc: "Rafael J. Wysocki" rjw@sisk.pl Tested-by: Martin Michlmayr tbm@cyrius.com Cc: stable@kernel.org [2.6.31.x] Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index ad41f19..12fdd39 100644 --- 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 */