net: dsa: assign a bridge number even without TX forwarding offload

The service where DSA assigns a unique bridge number for each forwarding
domain is useful even for drivers which do not implement the TX
forwarding offload feature.

For example, drivers might use the dp->bridge_num for FDB isolation.

So rename ds->num_fwd_offloading_bridges to ds->max_num_bridges, and
calculate a unique bridge_num for all drivers that set this value.
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Alvin Šipraga <alsi@bang-olufsen.dk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/mv88e6xxx/chip.c

@@ -3186,8 +3186,8 @@ static int mv88e6xxx_setup(struct dsa_switch *ds)
 	 * time.
 	 */
 	if (mv88e6xxx_has_pvt(chip))
-		ds->num_fwd_offloading_bridges = MV88E6XXX_MAX_PVT_SWITCHES -
-						 ds->dst->last_switch - 1;
+		ds->max_num_bridges = MV88E6XXX_MAX_PVT_SWITCHES -
+				      ds->dst->last_switch - 1;
 
 	mv88e6xxx_reg_lock(chip);
 

drivers/net/dsa/sja1105/sja1105_main.c

@@ -3139,7 +3139,7 @@ static int sja1105_setup(struct dsa_switch *ds)
 	ds->vlan_filtering_is_global = true;
 	ds->untag_bridge_pvid = true;
 	/* tag_8021q has 3 bits for the VBID, and the value 0 is reserved */
-	ds->num_fwd_offloading_bridges = 7;
+	ds->max_num_bridges = 7;
 
 	/* Advertise the 8 egress queues */
 	ds->num_tx_queues = SJA1105_NUM_TC;

include/net/dsa.h

@@ -413,12 +413,12 @@ struct dsa_switch {
 	 */
 	unsigned int		num_lag_ids;
 
-	/* Drivers that support bridge forwarding offload should set this to
-	 * the maximum number of bridges spanning the same switch tree (or all
-	 * trees, in the case of cross-tree bridging support) that can be
-	 * offloaded.
+	/* Drivers that support bridge forwarding offload or FDB isolation
+	 * should set this to the maximum number of bridges spanning the same
+	 * switch tree (or all trees, in the case of cross-tree bridging
+	 * support) that can be offloaded.
 	 */
-	unsigned int		num_fwd_offloading_bridges;
+	unsigned int		max_num_bridges;
 
 	size_t num_ports;
 };

net/dsa/dsa2.c

@@ -152,7 +152,9 @@ unsigned int dsa_bridge_num_get(const struct net_device *bridge_dev, int max)
 	unsigned int bridge_num = dsa_bridge_num_find(bridge_dev);
 
 	if (!bridge_num) {
-		/* First port that offloads TX forwarding for this bridge */
+		/* First port that requests FDB isolation or TX forwarding
+		 * offload for this bridge
+		 */
 		bridge_num = find_next_zero_bit(&dsa_fwd_offloading_bridges,
 						DSA_MAX_NUM_OFFLOADING_BRIDGES,
 						1);

net/dsa/port.c

@@ -271,19 +271,15 @@ static void dsa_port_switchdev_unsync_attrs(struct dsa_port *dp)
 }
 
 static void dsa_port_bridge_tx_fwd_unoffload(struct dsa_port *dp,
-					     struct net_device *bridge_dev)
+					     struct net_device *bridge_dev,
+					     unsigned int bridge_num)
 {
-	unsigned int bridge_num = dp->bridge_num;
 	struct dsa_switch *ds = dp->ds;
 
 	/* No bridge TX forwarding offload => do nothing */
-	if (!ds->ops->port_bridge_tx_fwd_unoffload || !dp->bridge_num)
+	if (!ds->ops->port_bridge_tx_fwd_unoffload || !bridge_num)
 		return;
 
-	dp->bridge_num = 0;
-
-	dsa_bridge_num_put(bridge_dev, bridge_num);
-
 	/* Notify the chips only once the offload has been deactivated, so
 	 * that they can update their configuration accordingly.
 	 */
@@ -292,31 +288,60 @@ static void dsa_port_bridge_tx_fwd_unoffload(struct dsa_port *dp,
 }
 
 static bool dsa_port_bridge_tx_fwd_offload(struct dsa_port *dp,
-					   struct net_device *bridge_dev)
+					   struct net_device *bridge_dev,
+					   unsigned int bridge_num)
 {
 	struct dsa_switch *ds = dp->ds;
-	unsigned int bridge_num;
 	int err;
 
-	if (!ds->ops->port_bridge_tx_fwd_offload)
-		return false;
-
-	bridge_num = dsa_bridge_num_get(bridge_dev,
-					ds->num_fwd_offloading_bridges);
-	if (!bridge_num)
+	/* FDB isolation is required for TX forwarding offload */
+	if (!ds->ops->port_bridge_tx_fwd_offload || !bridge_num)
 		return false;
 
-	dp->bridge_num = bridge_num;
-
 	/* Notify the driver */
 	err = ds->ops->port_bridge_tx_fwd_offload(ds, dp->index, bridge_dev,
 						  bridge_num);
-	if (err) {
-		dsa_port_bridge_tx_fwd_unoffload(dp, bridge_dev);
-		return false;
+
+	return err ? false : true;
+}
+
+static int dsa_port_bridge_create(struct dsa_port *dp,
+				  struct net_device *br,
+				  struct netlink_ext_ack *extack)
+{
+	struct dsa_switch *ds = dp->ds;
+	unsigned int bridge_num;
+
+	dp->bridge_dev = br;
+
+	if (!ds->max_num_bridges)
+		return 0;
+
+	bridge_num = dsa_bridge_num_get(br, ds->max_num_bridges);
+	if (!bridge_num) {
+		NL_SET_ERR_MSG_MOD(extack,
+				   "Range of offloadable bridges exceeded");
+		return -EOPNOTSUPP;
 	}
 
-	return true;
+	dp->bridge_num = bridge_num;
+
+	return 0;
+}
+
+static void dsa_port_bridge_destroy(struct dsa_port *dp,
+				    const struct net_device *br)
+{
+	struct dsa_switch *ds = dp->ds;
+
+	dp->bridge_dev = NULL;
+
+	if (ds->max_num_bridges) {
+		int bridge_num = dp->bridge_num;
+
+		dp->bridge_num = 0;
+		dsa_bridge_num_put(br, bridge_num);
+	}
 }
 
 int dsa_port_bridge_join(struct dsa_port *dp, struct net_device *br,
@@ -336,7 +361,9 @@ int dsa_port_bridge_join(struct dsa_port *dp, struct net_device *br,
 	/* Here the interface is already bridged. Reflect the current
 	 * configuration so that drivers can program their chips accordingly.
 	 */
-	dp->bridge_dev = br;
+	err = dsa_port_bridge_create(dp, br, extack);
+	if (err)
+		return err;
 
 	brport_dev = dsa_port_to_bridge_port(dp);
 
@@ -344,7 +371,8 @@ int dsa_port_bridge_join(struct dsa_port *dp, struct net_device *br,
 	if (err)
 		goto out_rollback;
 
-	tx_fwd_offload = dsa_port_bridge_tx_fwd_offload(dp, br);
+	tx_fwd_offload = dsa_port_bridge_tx_fwd_offload(dp, br,
+							dp->bridge_num);
 
 	err = switchdev_bridge_port_offload(brport_dev, dev, dp,
 					    &dsa_slave_switchdev_notifier,
@@ -366,7 +394,7 @@ int dsa_port_bridge_join(struct dsa_port *dp, struct net_device *br,
 out_rollback_unbridge:
 	dsa_broadcast(DSA_NOTIFIER_BRIDGE_LEAVE, &info);
 out_rollback:
-	dp->bridge_dev = NULL;
+	dsa_port_bridge_destroy(dp, br);
 	return err;
 }
 
@@ -393,14 +421,15 @@ void dsa_port_bridge_leave(struct dsa_port *dp, struct net_device *br)
 		.port = dp->index,
 		.br = br,
 	};
+	int bridge_num = dp->bridge_num;
 	int err;
 
 	/* Here the port is already unbridged. Reflect the current configuration
 	 * so that drivers can program their chips accordingly.
 	 */
-	dp->bridge_dev = NULL;
+	dsa_port_bridge_destroy(dp, br);
 
-	dsa_port_bridge_tx_fwd_unoffload(dp, br);
+	dsa_port_bridge_tx_fwd_unoffload(dp, br, bridge_num);
 
 	err = dsa_broadcast(DSA_NOTIFIER_BRIDGE_LEAVE, &info);
 	if (err)