bridge: Add br_fdb_clear_offload()

When a driver unoffloads all FDB entries en bloc, it's inefficient to
send the switchdev notification one by one. Add a helper that unsets the
offload flag on FDB entries on a given bridge port and VLAN.
Signed-off-by: Petr Machata <petrm@mellanox.com>
Acked-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/if_bridge.h

@@ -119,6 +119,7 @@ static inline int br_vlan_get_info(const struct net_device *dev, u16 vid,
 struct net_device *br_fdb_find_port(const struct net_device *br_dev,
 				    const unsigned char *addr,
 				    __u16 vid);
+void br_fdb_clear_offload(const struct net_device *dev, u16 vid);
 bool br_port_flag_is_set(const struct net_device *dev, unsigned long flag);
 #else
 static inline struct net_device *
@@ -128,6 +129,11 @@ br_fdb_find_port(const struct net_device *br_dev,
 {
 	return NULL;
 }
+
+static inline void br_fdb_clear_offload(const struct net_device *dev, u16 vid)
+{
+}
+
 static inline bool
 br_port_flag_is_set(const struct net_device *dev, unsigned long flag)
 {

net/bridge/br_fdb.c

@@ -1164,3 +1164,23 @@ void br_fdb_offloaded_set(struct net_bridge *br, struct net_bridge_port *p,
 
 	spin_unlock_bh(&br->hash_lock);
 }
+
+void br_fdb_clear_offload(const struct net_device *dev, u16 vid)
+{
+	struct net_bridge_fdb_entry *f;
+	struct net_bridge_port *p;
+
+	ASSERT_RTNL();
+
+	p = br_port_get_rtnl(dev);
+	if (!p)
+		return;
+
+	spin_lock_bh(&p->br->hash_lock);
+	hlist_for_each_entry(f, &p->br->fdb_list, fdb_node) {
+		if (f->dst == p && f->key.vlan_id == vid)
+			f->offloaded = 0;
+	}
+	spin_unlock_bh(&p->br->hash_lock);
+}
+EXPORT_SYMBOL_GPL(br_fdb_clear_offload);