mlxsw: spectrum: Clear VLAN filters during port initialization

When a port is created, its VLAN filters are not cleared by the
firmware. This causes tagged packets to be later dropped by the ingress
STP filters, which default to DISCARD state.

The above did not matter much until commit b5ce611fd9 ("mlxsw:
spectrum: Add devlink-trap support") where we exposed the drop reason to
users.

Without this patch, the drop reason users will see is not consistent. If
a port is enslaved to a VLAN-aware bridge and a packet with an invalid
VLAN tries to ingress the bridge, it will be dropped due to ingress STP
filter. If the VLAN is later enabled and then disabled, the packet will
be dropped by the ingress VLAN filter despite the above being a
seemingly NOP operation.

Fix this by clearing all the VLAN filters during port initialization.
Adjust the test accordingly.

Fixes: b5ce611fd9 ("mlxsw: spectrum: Add devlink-trap support")
Reported-by: Alex Kushnarov <alexanderk@mellanox.com>
Tested-by: Alex Kushnarov <alexanderk@mellanox.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlxsw/spectrum.c

@@ -3771,6 +3771,14 @@ static int mlxsw_sp_port_create(struct mlxsw_sp *mlxsw_sp, u8 local_port,
 		goto err_port_qdiscs_init;
 	}
 
+	err = mlxsw_sp_port_vlan_set(mlxsw_sp_port, 0, VLAN_N_VID - 1, false,
+				     false);
+	if (err) {
+		dev_err(mlxsw_sp->bus_info->dev, "Port %d: Failed to clear VLAN filter\n",
+			mlxsw_sp_port->local_port);
+		goto err_port_vlan_clear;
+	}
+
 	err = mlxsw_sp_port_nve_init(mlxsw_sp_port);
 	if (err) {
 		dev_err(mlxsw_sp->bus_info->dev, "Port %d: Failed to initialize NVE\n",
@@ -3818,6 +3826,7 @@ err_port_vlan_create:
 err_port_pvid_set:
 	mlxsw_sp_port_nve_fini(mlxsw_sp_port);
 err_port_nve_init:
+err_port_vlan_clear:
 	mlxsw_sp_tc_qdisc_fini(mlxsw_sp_port);
 err_port_qdiscs_init:
 	mlxsw_sp_port_fids_fini(mlxsw_sp_port);

tools/testing/selftests/drivers/net/mlxsw/devlink_trap_l2_drops.sh

@@ -224,13 +224,6 @@ ingress_vlan_filter_test()
 	local vid=10
 
 	bridge vlan add vid $vid dev $swp2 master
-	# During initialization the firmware enables all the VLAN filters and
-	# the driver does not turn them off since the traffic will be discarded
-	# by the STP filter whose default is DISCARD state. Add the VID on the
-	# ingress bridge port and then remove it to make sure it is not member
-	# in the VLAN.
-	bridge vlan add vid $vid dev $swp1 master
-	bridge vlan del vid $vid dev $swp1 master
 
 	RET=0