macvlan: Don't propagate IFF_ALLMULTI changes on down interfaces.

Clearing the IFF_ALLMULTI flag on a down interface could cause an allmulti
overflow on the underlying interface.

Attempting the set IFF_ALLMULTI on the underlying interface would cause an
error and the log message:

"allmulti touches root, set allmulti failed."
Signed-off-by: Peter Christensen <pch@ordbogen.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/macvlan.c

@@ -458,8 +458,10 @@ static void macvlan_change_rx_flags(struct net_device *dev, int change)
 	struct macvlan_dev *vlan = netdev_priv(dev);
 	struct net_device *lowerdev = vlan->lowerdev;
 
-	if (change & IFF_ALLMULTI)
-		dev_set_allmulti(lowerdev, dev->flags & IFF_ALLMULTI ? 1 : -1);
+	if (dev->flags & IFF_UP) {
+		if (change & IFF_ALLMULTI)
+			dev_set_allmulti(lowerdev, dev->flags & IFF_ALLMULTI ? 1 : -1);
+	}
 }
 
 static void macvlan_set_mac_lists(struct net_device *dev)