net: dsa: program VLAN on CPU port from slave

DSA currently programs a VLAN on the CPU port implicitly after the
related notifier is received by a switch.

While we still need to do this transparent programmation of the DSA
links in the fabric, programming the CPU port this way may cause
problems in some corners such as the tag_8021q driver.

Because the dedicated CPU port is specific to a slave, make their
programmation explicit a few layers up, in the slave code.

Note that technically, DSA links have a dedicated CPU port as well,
but since they are only used as conduit between interconnected switches
of a fabric, programming them transparently this way is what we want.
Signed-off-by: Vivien Didelot <vivien.didelot@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dsa/slave.c

@@ -332,6 +332,10 @@ static int dsa_slave_vlan_add(struct net_device *dev,
 	if (err)
 		return err;
 
+	err = dsa_port_vlan_add(dp->cpu_dp, &vlan, trans);
+	if (err)
+		return err;
+
 	return 0;
 }
 
@@ -383,6 +387,9 @@ static int dsa_slave_vlan_del(struct net_device *dev,
 	if (dp->bridge_dev && !br_vlan_enabled(dp->bridge_dev))
 		return 0;
 
+	/* Do not deprogram the CPU port as it may be shared with other user
+	 * ports which can be members of this VLAN as well.
+	 */
 	return dsa_port_vlan_del(dp, SWITCHDEV_OBJ_PORT_VLAN(obj));
 }
 
@@ -1121,6 +1128,10 @@ static int dsa_slave_vlan_rx_add_vid(struct net_device *dev, __be16 proto,
 	if (ret && ret != -EOPNOTSUPP)
 		return ret;
 
+	ret = dsa_port_vid_add(dp->cpu_dp, vid, 0);
+	if (ret && ret != -EOPNOTSUPP)
+		return ret;
+
 	return 0;
 }
 
@@ -1151,6 +1162,9 @@ static int dsa_slave_vlan_rx_kill_vid(struct net_device *dev, __be16 proto,
 	if (ret == -EOPNOTSUPP)
 		ret = 0;
 
+	/* Do not deprogram the CPU port as it may be shared with other user
+	 * ports which can be members of this VLAN as well.
+	 */
 	return ret;
 }
 

net/dsa/switch.c

@@ -232,7 +232,7 @@ static bool dsa_switch_vlan_match(struct dsa_switch *ds, int port,
 	if (ds->index == info->sw_index && port == info->port)
 		return true;
 
-	if (dsa_is_cpu_port(ds, port) || dsa_is_dsa_port(ds, port))
+	if (dsa_is_dsa_port(ds, port))
 		return true;
 
 	return false;
@@ -288,6 +288,9 @@ static int dsa_switch_vlan_del(struct dsa_switch *ds,
 	if (ds->index == info->sw_index)
 		return ds->ops->port_vlan_del(ds, info->port, info->vlan);
 
+	/* Do not deprogram the DSA links as they may be used as conduit
+	 * for other VLAN members in the fabric.
+	 */
 	return 0;
 }