net: bridge: fdb: add support for fine-grained flushing

Add the ability to specify exactly which fdbs to be flushed. They are
described by a new structure - net_bridge_fdb_flush_desc. Currently it
can match on port/bridge ifindex, vlan id and fdb flags. It is used to
describe the existing dynamic fdb flush operation. Note that this flush
operation doesn't treat permanent entries in a special way (fdb_delete vs
fdb_delete_local), it will delete them regardless if any port is using
them, so currently it can't directly replace deletes which need to handle
that case, although we can extend it later for that too.
Signed-off-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_fdb.c

@@ -558,24 +558,49 @@ void br_fdb_cleanup(struct work_struct *work)
 	mod_delayed_work(system_long_wq, &br->gc_work, work_delay);
 }
 
-/* Completely flush all dynamic entries in forwarding database.*/
-void br_fdb_flush(struct net_bridge *br)
+static bool __fdb_flush_matches(const struct net_bridge *br,
+				const struct net_bridge_fdb_entry *f,
+				const struct net_bridge_fdb_flush_desc *desc)
+{
+	const struct net_bridge_port *dst = READ_ONCE(f->dst);
+	int port_ifidx = dst ? dst->dev->ifindex : br->dev->ifindex;
+
+	if (desc->vlan_id && desc->vlan_id != f->key.vlan_id)
+		return false;
+	if (desc->port_ifindex && desc->port_ifindex != port_ifidx)
+		return false;
+	if (desc->flags_mask && (f->flags & desc->flags_mask) != desc->flags)
+		return false;
+
+	return true;
+}
+
+/* Flush forwarding database entries matching the description */
+void br_fdb_flush(struct net_bridge *br,
+		  const struct net_bridge_fdb_flush_desc *desc)
 {
 	struct net_bridge_fdb_entry *f;
-	struct hlist_node *tmp;
+
+	rcu_read_lock();
+	hlist_for_each_entry_rcu(f, &br->fdb_list, fdb_node) {
+		if (!__fdb_flush_matches(br, f, desc))
+			continue;
 
 		spin_lock_bh(&br->hash_lock);
-	hlist_for_each_entry_safe(f, tmp, &br->fdb_list, fdb_node) {
-		if (!test_bit(BR_FDB_STATIC, &f->flags))
+		if (!hlist_unhashed(&f->fdb_node))
 			fdb_delete(br, f, true);
-	}
 		spin_unlock_bh(&br->hash_lock);
+	}
+	rcu_read_unlock();
 }
 
 int br_fdb_delete_bulk(struct ndmsg *ndm, struct nlattr *tb[],
 		       struct net_device *dev, u16 vid,
 		       struct netlink_ext_ack *extack)
 {
+	struct net_bridge_fdb_flush_desc desc = {
+		.flags_mask = BR_FDB_STATIC
+	};
 	struct net_bridge_port *p = NULL;
 	struct net_bridge *br;
 
@@ -590,7 +615,7 @@ int br_fdb_delete_bulk(struct ndmsg *ndm, struct nlattr *tb[],
 		br = p->br;
 	}
 
-	br_fdb_flush(br);
+	br_fdb_flush(br, &desc);
 
 	return 0;
 }

net/bridge/br_netlink.c

@@ -1326,8 +1326,13 @@ static int br_changelink(struct net_device *brdev, struct nlattr *tb[],
 		br_recalculate_fwd_mask(br);
 	}
 
-	if (data[IFLA_BR_FDB_FLUSH])
-		br_fdb_flush(br);
+	if (data[IFLA_BR_FDB_FLUSH]) {
+		struct net_bridge_fdb_flush_desc desc = {
+			.flags_mask = BR_FDB_STATIC
+		};
+
+		br_fdb_flush(br, &desc);
+	}
 
 #ifdef CONFIG_BRIDGE_IGMP_SNOOPING
 	if (data[IFLA_BR_MCAST_ROUTER]) {

net/bridge/br_private.h

@@ -274,6 +274,13 @@ struct net_bridge_fdb_entry {
 	struct rcu_head			rcu;
 };
 
+struct net_bridge_fdb_flush_desc {
+	unsigned long			flags;
+	unsigned long			flags_mask;
+	int				port_ifindex;
+	u16				vlan_id;
+};
+
 #define MDB_PG_FLAGS_PERMANENT	BIT(0)
 #define MDB_PG_FLAGS_OFFLOAD	BIT(1)
 #define MDB_PG_FLAGS_FAST_LEAVE	BIT(2)
@@ -759,7 +766,8 @@ int br_fdb_init(void);
 void br_fdb_fini(void);
 int br_fdb_hash_init(struct net_bridge *br);
 void br_fdb_hash_fini(struct net_bridge *br);
-void br_fdb_flush(struct net_bridge *br);
+void br_fdb_flush(struct net_bridge *br,
+		  const struct net_bridge_fdb_flush_desc *desc);
 void br_fdb_find_delete_local(struct net_bridge *br,
 			      const struct net_bridge_port *p,
 			      const unsigned char *addr, u16 vid);

net/bridge/br_sysfs_br.c

@@ -344,7 +344,11 @@ static DEVICE_ATTR_RW(group_addr);
 static int set_flush(struct net_bridge *br, unsigned long val,
 		     struct netlink_ext_ack *extack)
 {
-	br_fdb_flush(br);
+	struct net_bridge_fdb_flush_desc desc = {
+		.flags_mask = BR_FDB_STATIC
+	};
+
+	br_fdb_flush(br, &desc);
 	return 0;
 }