From ee01e663373343c63e0e3d364d09f6155378dbcc Mon Sep 17 00:00:00 2001
From: Toshi Kani <toshi.kani@hp.com>
Date: Sat, 31 Mar 2012 21:37:02 -0600
Subject: [PATCH] cpuidle: Fix panic in CPU off-lining with no idle driver
Fix a NULL pointer dereference panic in cpuidle_play_dead() during
CPU off-lining when no cpuidle driver is registered. A cpuidle
driver may be registered at boot-time based on CPU type. This patch
allows an off-lined CPU to enter HLT-based idle in this condition.
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Cc: Boris Ostrovsky <boris.ostrovsky@amd.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Tested-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Len Brown <len.brown@intel.com>
---
drivers/cpuidle/cpuidle.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 3e146b2ada4a1..a71376a45d8e6 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -74,7 +74,7 @@ static cpuidle_enter_t cpuidle_enter_ops;
/**
* cpuidle_play_dead - cpu off-lining
*
- * Only returns in case of an error
+ * Returns in case of an error or no driver
*/
int cpuidle_play_dead(void)
{
@@ -83,6 +83,9 @@ int cpuidle_play_dead(void)
int i, dead_state = -1;
int power_usage = -1;
+ if (!drv)
+ return -ENODEV;
+
/* Find lowest-power state that supports long-term idle */
for (i = CPUIDLE_DRIVER_STATE_START; i < drv->state_count; i++) {
struct cpuidle_state *s = &drv->states[i];
--
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