net: dpaa2-switch: refactor prechangeupper sanity checks

Make more room for some extra code in the NETDEV_PRECHANGEUPPER handler
by moving what already exists into a dedicated function.

Cc: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Acked-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/dpaa2/dpaa2-switch.c

@@ -2030,6 +2030,28 @@ static int dpaa2_switch_prevent_bridging_with_8021q_upper(struct net_device *net
 	return 0;
 }
 
+static int
+dpaa2_switch_prechangeupper_sanity_checks(struct net_device *netdev,
+					  struct net_device *upper_dev,
+					  struct netlink_ext_ack *extack)
+{
+	int err;
+
+	if (!br_vlan_enabled(upper_dev)) {
+		NL_SET_ERR_MSG_MOD(extack, "Cannot join a VLAN-unaware bridge");
+		return -EOPNOTSUPP;
+	}
+
+	err = dpaa2_switch_prevent_bridging_with_8021q_upper(netdev);
+	if (err) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "Cannot join a bridge while VLAN uppers are present");
+		return 0;
+	}
+
+	return 0;
+}
+
 static int dpaa2_switch_port_netdevice_event(struct notifier_block *nb,
 					     unsigned long event, void *ptr)
 {
@@ -2050,18 +2072,11 @@ static int dpaa2_switch_port_netdevice_event(struct notifier_block *nb,
 		if (!netif_is_bridge_master(upper_dev))
 			break;
 
-		if (!br_vlan_enabled(upper_dev)) {
-			NL_SET_ERR_MSG_MOD(extack, "Cannot join a VLAN-unaware bridge");
-			err = -EOPNOTSUPP;
+		err = dpaa2_switch_prechangeupper_sanity_checks(netdev,
+								upper_dev,
+								extack);
+		if (err)
 			goto out;
-		}
-
-		err = dpaa2_switch_prevent_bridging_with_8021q_upper(netdev);
-		if (err) {
-			NL_SET_ERR_MSG_MOD(extack,
-					   "Cannot join a bridge while VLAN uppers are present");
-			goto out;
-		}
 
 		break;
 	case NETDEV_CHANGEUPPER: