cpuidle: Check the result of cpuidle_get_driver() against NULL
commit
3b9c10e98021e1f92e6f8c7ce1778b86ba68db10 upstream.
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>
Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>