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>

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index 3e146b2..a71376a 100644 (file)
--- 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];