cpuidle: Check the result of cpuidle_get_driver() against NULL

If the current CPU has no cpuidle driver, drv will be NULL in
cpuidle_driver_ref().  Check if that is the case before trying
to bump up the driver's refcount to prevent the kernel from
crashing.

[rjw: Subject and changelog]
Signed-off-by: Daniel Fu <danifu@nvidia.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/cpuidle/driver.c b/drivers/cpuidle/driver.c
index 3ac499d5a207..6e11701f0fca 100644
--- a/drivers/cpuidle/driver.c
+++ b/drivers/cpuidle/driver.c
@@ -331,7 +331,8 @@ struct cpuidle_driver *cpuidle_driver_ref(void)
         spin_lock(&cpuidle_driver_lock);
 
         drv = cpuidle_get_driver();
-        drv->refcnt++;
+        if (drv)
+                drv->refcnt++;
 
         spin_unlock(&cpuidle_driver_lock);
         return drv;