network: prevent unnecessary interface down/up cycles if no mac address change is requested

SVN-Revision: 16269

package/base-files/files/lib/network/config.sh

@@ -246,9 +246,10 @@ setup_interface() {
 	# Interface settings
 	config_get mtu "$config" mtu
 	config_get macaddr "$config" macaddr
-	grep "$iface:" /proc/net/dev > /dev/null && \
-		$DEBUG ifconfig "$iface" down && \
+	grep "$iface:" /proc/net/dev > /dev/null && {
+		[ -n "$macaddr" ] && $DEBUG ifconfig "$iface" down
 		$DEBUG ifconfig "$iface" ${macaddr:+hw ether "$macaddr"} ${mtu:+mtu $mtu} up
+	}
 	set_interface_ifname "$config" "$iface"
 
 	pidfile="/var/run/$iface.pid"