net: dsa: request drivers to perform FDB isolation

For DSA, to encourage drivers to perform FDB isolation simply means to
track which bridge does each FDB and MDB entry belong to. It then
becomes the driver responsibility to use something that makes the FDB
entry from one bridge not match the FDB lookup of ports from other
bridges.

The top-level functions where the bridge is determined are:
- dsa_port_fdb_{add,del}
- dsa_port_host_fdb_{add,del}
- dsa_port_mdb_{add,del}
- dsa_port_host_mdb_{add,del}

aka the pre-crosschip-notifier functions.

Changing the API to pass a reference to a bridge is not superfluous, and
looking at the passed bridge argument is not the same as having the
driver look at dsa_to_port(ds, port)->bridge from the ->port_fdb_add()
method.

DSA installs FDB and MDB entries on shared (CPU and DSA) ports as well,
and those do not have any dp->bridge information to retrieve, because
they are not in any bridge - they are merely the pipes that serve the
user ports that are in one or multiple bridges.

The struct dsa_bridge associated with each FDB/MDB entry is encapsulated
in a larger "struct dsa_db" database. Although only databases associated
to bridges are notified for now, this API will be the starting point for
implementing IFF_UNICAST_FLT in DSA. There, the idea is to install FDB
entries on the CPU port which belong to the corresponding user port's
port database. These are supposed to match only when the port is
standalone.

It is better to introduce the API in its expected final form than to
introduce it for bridges first, then to have to change drivers which may
have made one or more assumptions.

Drivers can use the provided bridge.num, but they can also use a
different numbering scheme that is more convenient.

DSA must perform refcounting on the CPU and DSA ports by also taking
into account the bridge number. So if two bridges request the same local
address, DSA must notify the driver twice, once for each bridge.

In fact, if the driver supports FDB isolation, DSA must perform
refcounting per bridge, but if the driver doesn't, DSA must refcount
host addresses across all bridges, otherwise it would be telling the
driver to delete an FDB entry for a bridge and the driver would delete
it for all bridges. So introduce a bool fdb_isolation in drivers which
would make all bridge databases passed to the cross-chip notifier have
the same number (0). This makes dsa_mac_addr_find() -> dsa_db_equal()
say that all bridge databases are the same database - which is
essentially the legacy behavior.

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

1 files changed, 36 insertions, 6 deletions

diff --git a/include/net/dsa.h b/include/net/dsa.h
index 01faba89c987..87c5f18eb381 100644
--- a/include/net/dsa.h
+++ b/include/net/dsa.h
@@ -341,11 +341,28 @@ struct dsa_link {
 	struct list_head list;
 };
 
+enum dsa_db_type {
+	DSA_DB_PORT,
+	DSA_DB_LAG,
+	DSA_DB_BRIDGE,
+};
+
+struct dsa_db {
+	enum dsa_db_type type;
+
+	union {
+		const struct dsa_port *dp;
+		struct dsa_lag lag;
+		struct dsa_bridge bridge;
+	};
+};
+
 struct dsa_mac_addr {
 	unsigned char addr[ETH_ALEN];
 	u16 vid;
 	refcount_t refcount;
 	struct list_head list;
+	struct dsa_db db;
 };
 
 struct dsa_vlan {
@@ -409,6 +426,13 @@ struct dsa_switch {
 	 */
 	u32			mtu_enforcement_ingress:1;
 
+	/* Drivers that isolate the FDBs of multiple bridges must set this
+	 * to true to receive the bridge as an argument in .port_fdb_{add,del}
+	 * and .port_mdb_{add,del}. Otherwise, the bridge.num will always be
+	 * passed as zero.
+	 */
+	u32			fdb_isolation:1;
+
 	/* Listener for switch fabric events */
 	struct notifier_block	nb;
 
@@ -941,23 +965,29 @@ struct dsa_switch_ops {
 	 * Forwarding database
 	 */
 	int	(*port_fdb_add)(struct dsa_switch *ds, int port,
-				const unsigned char *addr, u16 vid);
+				const unsigned char *addr, u16 vid,
+				struct dsa_db db);
 	int	(*port_fdb_del)(struct dsa_switch *ds, int port,
-				const unsigned char *addr, u16 vid);
+				const unsigned char *addr, u16 vid,
+				struct dsa_db db);
 	int	(*port_fdb_dump)(struct dsa_switch *ds, int port,
 				 dsa_fdb_dump_cb_t *cb, void *data);
 	int	(*lag_fdb_add)(struct dsa_switch *ds, struct dsa_lag lag,
-			       const unsigned char *addr, u16 vid);
+			       const unsigned char *addr, u16 vid,
+			       struct dsa_db db);
 	int	(*lag_fdb_del)(struct dsa_switch *ds, struct dsa_lag lag,
-			       const unsigned char *addr, u16 vid);
+			       const unsigned char *addr, u16 vid,
+			       struct dsa_db db);
 
 	/*
 	 * Multicast database
 	 */
 	int	(*port_mdb_add)(struct dsa_switch *ds, int port,
-				const struct switchdev_obj_port_mdb *mdb);
+				const struct switchdev_obj_port_mdb *mdb,
+				struct dsa_db db);
 	int	(*port_mdb_del)(struct dsa_switch *ds, int port,
-				const struct switchdev_obj_port_mdb *mdb);
+				const struct switchdev_obj_port_mdb *mdb,
+				struct dsa_db db);
 	/*
 	 * RXNFC
 	 */