diff --git a/[refs] b/[refs]
index 36c1b46ee5b2..287df90bd7e2 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7727da22e820a96ab394db2fc0ab58f7f7ecb323
+refs/heads/master: 3aa713e76e8f562c0d28faf18873c4f1836b17c9
diff --git a/trunk/drivers/regulator/core.c b/trunk/drivers/regulator/core.c
index 711fa1722bce..27d062e1395c 100644
--- a/trunk/drivers/regulator/core.c
+++ b/trunk/drivers/regulator/core.c
@@ -1269,7 +1269,9 @@ static int _regulator_enable(struct regulator_dev *rdev)
 
 	/* do we need to enable the supply regulator first */
 	if (rdev->supply) {
+		mutex_lock(&rdev->supply->mutex);
 		ret = _regulator_enable(rdev->supply);
+		mutex_unlock(&rdev->supply->mutex);
 		if (ret < 0) {
 			printk(KERN_ERR "%s: failed to enable %s: %d\n",
 			       __func__, rdev_get_name(rdev), ret);