[3.5.y.z extended stable] Patch "intel_idle: Check cpu_idle_get_driver() for NULL before dereferencing" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    intel_idle: Check cpu_idle_get_driver() for NULL before dereferencing

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From b405ad5642840b37a953db5d741e550096aa035c Mon Sep 17 00:00:00 2001
From: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Date: Thu, 16 Aug 2012 22:06:55 +0200
Subject: intel_idle: Check cpu_idle_get_driver() for NULL before dereferencing
 it.

commit 3735d524da64b70b41c764359da36f88aded3610 upstream.

If the machine is booted without any cpu_idle driver set
(b/c disable_cpuidle() has been called) we should follow
other users of cpu_idle API and check the return value
for NULL before using it.

Reported-and-tested-by: Mark van Dijk <mark at internecto.net>
Suggested-by: Jan Beulich <JBeulich at suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk at oracle.com>
Signed-off-by: Rafael J. Wysocki <rjw at sisk.pl>
Cc: Daniel Kiper <daniel.kiper at oracle.com>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/idle/intel_idle.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index 674e352..9b09185 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -592,8 +592,9 @@ static int __init intel_idle_init(void)
 	intel_idle_cpuidle_driver_init();
 	retval = cpuidle_register_driver(&intel_idle_driver);
 	if (retval) {
+		struct cpuidle_driver *drv = cpuidle_get_driver();
 		printk(KERN_DEBUG PREFIX "intel_idle yielding to %s",
-			cpuidle_get_driver()->name);
+			drv ? drv->name : "none");
 		return retval;
 	}

--
1.9.1