cpufreq: Clean up after a failing light-weight initialization

If cpufreq_policy_restore() returns NULL during system resume,
__cpufreq_add_dev() should just fall back to the full initialization
instead of returning an error, because that may actually make things
work.  Moreover, it should not leave stale fallback data behind after
it has failed to restore a previously existing policy.

This change is based on Viresh Kumar's work.

Fixes: 5302c3fb2e62 ("cpufreq: Perform light-weight init/teardown during suspend/resume")
Reported-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Cc: 3.12+ <stable@vger.kernel.org> # 3.12+

drivers/cpufreq/cpufreq.c

@@ -1016,15 +1016,17 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif,
 	read_unlock_irqrestore(&cpufreq_driver_lock, flags);
 #endif
 
-	if (frozen)
-		/* Restore the saved policy when doing light-weight init */
-		policy = cpufreq_policy_restore(cpu);
-	else
+	/*
+	 * Restore the saved policy when doing light-weight init and fall back
+	 * to the full init if that fails.
+	 */
+	policy = frozen ? cpufreq_policy_restore(cpu) : NULL;
+	if (!policy) {
+		frozen = false;
 		policy = cpufreq_policy_alloc();
-
-	if (!policy)
-		goto nomem_out;
-
+		if (!policy)
+			goto nomem_out;
+	}
 
 	/*
 	 * In the resume path, since we restore a saved policy, the assignment
@@ -1118,8 +1120,11 @@ err_get_freq:
 	if (cpufreq_driver->exit)
 		cpufreq_driver->exit(policy);
 err_set_policy_cpu:
-	if (frozen)
+	if (frozen) {
+		/* Do not leave stale fallback data behind. */
+		per_cpu(cpufreq_cpu_data_fallback, cpu) = NULL;
 		cpufreq_policy_put_kobj(policy);
+	}
 	cpufreq_policy_free(policy);
 
 nomem_out: