diff --git a/[refs] b/[refs]
index 016770946b4b..b321acbb4055 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a81135d90bf176e6139c352c7b96c03d00131836
+refs/heads/master: 313d7b003ceceb797e8c0d18ab085ed0638b4aff
diff --git a/trunk/drivers/xen/blkback/xenbus.c b/trunk/drivers/xen/blkback/xenbus.c
index a0534fc6a428..031bc3d7eec3 100644
--- a/trunk/drivers/xen/blkback/xenbus.c
+++ b/trunk/drivers/xen/blkback/xenbus.c
@@ -382,6 +382,11 @@ static void frontend_changed(struct xenbus_device *dev,
 		if (dev->state == XenbusStateConnected)
 			break;
 
+		/* Enforce precondition before potential leak point.
+		 * blkif_disconnect() is idempotent.
+		 */
+		blkif_disconnect(be->blkif);
+
 		err = connect_ring(be);
 		if (err)
 			break;
@@ -399,6 +404,7 @@ static void frontend_changed(struct xenbus_device *dev,
 			break;
 		/* fall through if not online */
 	case XenbusStateUnknown:
+		/* implies blkif_disconnect() via blkback_remove() */
 		device_unregister(&dev->dev);
 		break;