net: bridge: BROPT_FDB_LOCAL_VLAN_0: On port changeaddr, skip per-VLAN FDBs

When BROPT_FDB_LOCAL_VLAN_0 is enabled, the local FDB entries for member
ports should not be created per-VLAN, but instead only on VLAN 0. When the
member port address changes, the local FDB entries need to be updated,
which is done in br_fdb_changeaddr().

Under the VLAN-0 mode, only one local FDB entry will ever be added for a
port's address, and that on VLAN 0. Thus bail out of the delete loop early.
For the same reason, also skip adding the per-VLAN entries.

Reviewed-by: Ido Schimmel <[email protected]>
Signed-off-by: Petr Machata <[email protected]>
Acked-by: Nikolay Aleksandrov <[email protected]>
Link: https://patch.msgid.link/0cf9d41836d2a245b0ce07e1a16ee05ca506cbe9.1757004393.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <[email protected]>

Author: pmachata

net/bridge/br_fdb.c

@@ -459,6 +459,9 @@ void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
 	struct net_bridge_fdb_entry *f;
 	struct net_bridge *br = p->br;
 	struct net_bridge_vlan *v;
+	bool local_vlan_0;
+
+	local_vlan_0 = br_opt_get(br, BROPT_FDB_LOCAL_VLAN_0);
 
 	spin_lock_bh(&br->hash_lock);
 	vg = nbp_vlan_group(p);
@@ -468,11 +471,11 @@ void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
 			/* delete old one */
 			fdb_delete_local(br, p, f);
 
-			/* if this port has no vlan information
-			 * configured, we can safely be done at
-			 * this point.
+			/* if this port has no vlan information configured, or
+			 * local entries are only kept on VLAN 0, we can safely
+			 * be done at this point.
 			 */
-			if (!vg || !vg->num_vlans)
+			if (!vg || !vg->num_vlans || local_vlan_0)
 				goto insert;
 		}
 	}
@@ -481,7 +484,7 @@ void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
 	/* insert new address,  may fail if invalid address or dup. */
 	fdb_add_local(br, p, newaddr, 0);
 
-	if (!vg || !vg->num_vlans)
+	if (!vg || !vg->num_vlans || local_vlan_0)
 		goto done;
 
 	/* Now add entries for every VLAN configured on the port.