[PATCH] intel_idle: Check cpu_idle_get_driver() for NULL beforedereferencing it.

[Konrad Rzeszutek Wilk]

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-by: Mark van Dijk <mark@xxxxxxxxxxxxxx>
Tested-by: Mark van Dijk <mark@xxxxxxxxxxxxxx>
Suggested-by: Jan Beulich <JBeulich@xxxxxxxx>
[v1: Redo per Rafael's suggestion]
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 drivers/idle/intel_idle.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
index d0f59c3..6b313af 100644
--- a/drivers/idle/intel_idle.c
+++ b/drivers/idle/intel_idle.c
@@ -556,8 +556,9 @@ 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;
 	}
 
-- 
1.7.7.6

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