cpuidle: always return with interrupts enabled
authorKevin Hilman <khilman@deeprootsystems.com>
Mon, 26 Oct 2009 23:50:18 +0000 (16:50 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 29 Oct 2009 14:39:31 +0000 (07:39 -0700)
commit246eb7f0ed1a8aeddec5313137767658f378949b
tree25cfbdab4d133ebb1539b3c8b4e302f1ca7866b3
parent5e8d8f6f2844d4a663415c660ab5cc92e2e2477d
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>
drivers/cpuidle/cpuidle.c