diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 45e053e..1a78ad9 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -1023,11 +1023,18 @@
  */
 int devfreq_register_opp_notifier(struct device *dev, struct devfreq *devfreq)
 {
-	struct srcu_notifier_head *nh = opp_get_notifier(dev);
+	struct srcu_notifier_head *nh;
+	int ret = 0;
 
+	rcu_read_lock();
+	nh = opp_get_notifier(dev);
 	if (IS_ERR(nh))
-		return PTR_ERR(nh);
-	return srcu_notifier_chain_register(nh, &devfreq->nb);
+		ret = PTR_ERR(nh);
+	rcu_read_unlock();
+	if (!ret)
+		ret = srcu_notifier_chain_register(nh, &devfreq->nb);
+
+	return ret;
 }
 
 /**
@@ -1042,11 +1049,18 @@
  */
 int devfreq_unregister_opp_notifier(struct device *dev, struct devfreq *devfreq)
 {
-	struct srcu_notifier_head *nh = opp_get_notifier(dev);
+	struct srcu_notifier_head *nh;
+	int ret = 0;
 
+	rcu_read_lock();
+	nh = opp_get_notifier(dev);
 	if (IS_ERR(nh))
-		return PTR_ERR(nh);
-	return srcu_notifier_chain_unregister(nh, &devfreq->nb);
+		ret = PTR_ERR(nh);
+	rcu_read_unlock();
+	if (!ret)
+		ret = srcu_notifier_chain_unregister(nh, &devfreq->nb);
+
+	return ret;
 }
 
 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>");