net: bridge: switchdev: differentiate new VLANs from changed ones

br_switchdev_port_vlan_add() currently emits a SWITCHDEV_PORT_OBJ_ADD
event with a SWITCHDEV_OBJ_ID_PORT_VLAN for 2 distinct cases:

- a struct net_bridge_vlan got created
- an existing struct net_bridge_vlan was modified

This makes it impossible for switchdev drivers to properly balance
PORT_OBJ_ADD with PORT_OBJ_DEL events, so if we want to allow that to
happen, we must provide a way for drivers to distinguish between a
VLAN with changed flags and a new one.

Annotate struct switchdev_obj_port_vlan with a "bool changed" that
distinguishes the 2 cases above.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: vladimiroltean

include/net/switchdev.h

@@ -81,6 +81,13 @@ struct switchdev_obj_port_vlan {
 	struct switchdev_obj obj;
 	u16 flags;
 	u16 vid;
+	/* If set, the notifier signifies a change of one of the following
+	 * flags for a VLAN that already exists:
+	 * - BRIDGE_VLAN_INFO_PVID
+	 * - BRIDGE_VLAN_INFO_UNTAGGED
+	 * Entries with BRIDGE_VLAN_INFO_BRENTRY unset are not notified at all.
+	 */
+	bool changed;
 };
 
 #define SWITCHDEV_OBJ_PORT_VLAN(OBJ) \

net/bridge/br_private.h

@@ -1985,7 +1985,7 @@ void br_switchdev_mdb_notify(struct net_device *dev,
 			     struct net_bridge_port_group *pg,
 			     int type);
 int br_switchdev_port_vlan_add(struct net_device *dev, u16 vid, u16 flags,
-			       struct netlink_ext_ack *extack);
+			       bool changed, struct netlink_ext_ack *extack);
 int br_switchdev_port_vlan_del(struct net_device *dev, u16 vid);
 void br_switchdev_init(struct net_bridge *br);
 
@@ -2052,8 +2052,8 @@ static inline int br_switchdev_set_port_flag(struct net_bridge_port *p,
 	return 0;
 }
 
-static inline int br_switchdev_port_vlan_add(struct net_device *dev,
-					     u16 vid, u16 flags,
+static inline int br_switchdev_port_vlan_add(struct net_device *dev, u16 vid,
+					     u16 flags, bool changed,
 					     struct netlink_ext_ack *extack)
 {
 	return -EOPNOTSUPP;

net/bridge/br_switchdev.c

@@ -160,13 +160,14 @@ br_switchdev_fdb_notify(struct net_bridge *br,
 }
 
 int br_switchdev_port_vlan_add(struct net_device *dev, u16 vid, u16 flags,
-			       struct netlink_ext_ack *extack)
+			       bool changed, struct netlink_ext_ack *extack)
 {
 	struct switchdev_obj_port_vlan v = {
 		.obj.orig_dev = dev,
 		.obj.id = SWITCHDEV_OBJ_ID_PORT_VLAN,
 		.flags = flags,
 		.vid = vid,
+		.changed = changed,
 	};
 
 	return switchdev_port_obj_add(dev, &v.obj, extack);

net/bridge/br_vlan.c

@@ -109,7 +109,7 @@ static int __vlan_vid_add(struct net_device *dev, struct net_bridge *br,
 	/* Try switchdev op first. In case it is not supported, fallback to
 	 * 8021q add.
 	 */
-	err = br_switchdev_port_vlan_add(dev, v->vid, flags, extack);
+	err = br_switchdev_port_vlan_add(dev, v->vid, flags, false, extack);
 	if (err == -EOPNOTSUPP)
 		return vlan_vid_add(dev, br->vlan_proto, v->vid);
 	v->priv_flags |= BR_VLFLAG_ADDED_BY_SWITCHDEV;
@@ -303,7 +303,7 @@ static int __vlan_add(struct net_bridge_vlan *v, u16 flags,
 	} else {
 		if (br_vlan_should_use(v)) {
 			err = br_switchdev_port_vlan_add(dev, v->vid, flags,
-							 extack);
+							 false, extack);
 			if (err && err != -EOPNOTSUPP)
 				goto out;
 		}
@@ -714,7 +714,7 @@ static int br_vlan_add_existing(struct net_bridge *br,
 	 */
 	if (becomes_brentry || would_change) {
 		err = br_switchdev_port_vlan_add(br->dev, vlan->vid, flags,
-						 extack);
+						 would_change, extack);
 		if (err && err != -EOPNOTSUPP)
 			return err;
 	}
@@ -1289,8 +1289,8 @@ int nbp_vlan_add(struct net_bridge_port *port, u16 vid, u16 flags,
 
 		if (would_change) {
 			/* Pass the flags to the hardware bridge */
-			ret = br_switchdev_port_vlan_add(port->dev, vid,
-							 flags, extack);
+			ret = br_switchdev_port_vlan_add(port->dev, vid, flags,
+							 true, extack);
 			if (ret && ret != -EOPNOTSUPP)
 				return ret;
 		}