drivers: net: cpsw: discard dual emac default vlan configuration

In Dual EMAC, the default VLANs are used to segregate Rx packets between
the ports, so adding the same default VLAN to the switch will affect the
normal packet transfers. So returning error on addition of dual EMAC
default VLANs.

Even if EMAC 0 default port VLAN is added to EMAC 1, it will lead to
break dual EMAC port separations.

Fixes: d9ba8f9e6298 (driver: net: ethernet: cpsw: dual emac interface implementation)
Cc: <stable@vger.kernel.org> # v3.9+
Reported-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/cpsw.c

@@ -1683,6 +1683,19 @@ static int cpsw_ndo_vlan_rx_add_vid(struct net_device *ndev,
 	if (vid == priv->data.default_vlan)
 		return 0;
 
+	if (priv->data.dual_emac) {
+		/* In dual EMAC, reserved VLAN id should not be used for
+		 * creating VLAN interfaces as this can break the dual
+		 * EMAC port separation
+		 */
+		int i;
+
+		for (i = 0; i < priv->data.slaves; i++) {
+			if (vid == priv->slaves[i].port_vlan)
+				return -EINVAL;
+		}
+	}
+
 	dev_info(priv->dev, "Adding vlanid %d to vlan filter\n", vid);
 	return cpsw_add_vlan_ale_entry(priv, vid);
 }
@@ -1696,6 +1709,15 @@ static int cpsw_ndo_vlan_rx_kill_vid(struct net_device *ndev,
 	if (vid == priv->data.default_vlan)
 		return 0;
 
+	if (priv->data.dual_emac) {
+		int i;
+
+		for (i = 0; i < priv->data.slaves; i++) {
+			if (vid == priv->slaves[i].port_vlan)
+				return -EINVAL;
+		}
+	}
+
 	dev_info(priv->dev, "removing vlanid %d from vlan filter\n", vid);
 	ret = cpsw_ale_del_vlan(priv->ale, vid, 0);
 	if (ret != 0)