net: dsa: set configure_vlan_while_not_filtering to true by default

As explained in commit 54a0ed0df496 ("net: dsa: provide an option for
drivers to always receive bridge VLANs"), DSA has historically been
skipping VLAN switchdev operations when the bridge wasn't in
vlan_filtering mode, but the reason why it was doing that has never been
clear. So the configure_vlan_while_not_filtering option is there merely
to preserve functionality for existing drivers. It isn't some behavior
that drivers should opt into. Ideally, when all drivers leave this flag
set, we can delete the dsa_port_skip_vlan_configuration() function.

New drivers always seem to omit setting this flag, for some reason. So
let's reverse the logic: the DSA core sets it by default to true before
the .setup() callback, and legacy drivers can turn it off. This way, new
drivers get the new behavior by default, unless they explicitly set the
flag to false, which is more obvious during review.

Remove the assignment from drivers which were setting it to true, and
add the assignment to false for the drivers that didn't previously have
it. This way, it should be easier to see how many we have left.

The following drivers: lan9303, mv88e6060 were skipped from setting this
flag to false, because they didn't have any VLAN offload ops in the
first place.

The Broadcom Starfighter 2 driver calls the common b53_switch_alloc and
therefore also inherits the configure_vlan_while_not_filtering=true
behavior.

Also, print a message through netlink extack every time a VLAN has been
skipped. This is mildly annoying on purpose, so that (a) it is at least
clear that VLANs are being skipped - the legacy behavior in itself is
confusing, and the extack should be much more difficult to miss, unlike
kernel logs - and (b) people have one more incentive to convert to the
new behavior.

No behavior change except for the added prints is intended at this time.

$ ip link add br0 type bridge vlan_filtering 0
$ ip link set sw0p2 master br0
[   60.315148] br0: port 1(sw0p2) entered blocking state
[   60.320350] br0: port 1(sw0p2) entered disabled state
[   60.327839] device sw0p2 entered promiscuous mode
[   60.334905] br0: port 1(sw0p2) entered blocking state
[   60.340142] br0: port 1(sw0p2) entered forwarding state
Warning: dsa_core: skipping configuration of VLAN. # This was the pvid
$ bridge vlan add dev sw0p2 vid 100
Warning: dsa_core: skipping configuration of VLAN.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Kurt Kanzenbach <kurt@linutronix.de>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20210115231919.43834-1-vladimir.oltean@nxp.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/net/dsa/slave.c b/net/dsa/slave.c
index c5c81cba8259..f2fb433f3828 100644
--- a/net/dsa/slave.c
+++ b/net/dsa/slave.c
@@ -326,7 +326,8 @@ dsa_slave_vlan_check_for_8021q_uppers(struct net_device *slave,
 }
 
 static int dsa_slave_vlan_add(struct net_device *dev,
-			      const struct switchdev_obj *obj)
+			      const struct switchdev_obj *obj,
+			      struct netlink_ext_ack *extack)
 {
 	struct net_device *master = dsa_slave_to_master(dev);
 	struct dsa_port *dp = dsa_slave_to_port(dev);
@@ -336,8 +337,10 @@ static int dsa_slave_vlan_add(struct net_device *dev,
 	if (!dsa_port_offloads_netdev(dp, obj->orig_dev))
 		return -EOPNOTSUPP;
 
-	if (dsa_port_skip_vlan_configuration(dp))
+	if (dsa_port_skip_vlan_configuration(dp)) {
+		NL_SET_ERR_MSG_MOD(extack, "skipping configuration of VLAN");
 		return 0;
+	}
 
 	vlan = *SWITCHDEV_OBJ_PORT_VLAN(obj);
 
@@ -389,7 +392,7 @@ static int dsa_slave_port_obj_add(struct net_device *dev,
 		err = dsa_port_mdb_add(dp->cpu_dp, SWITCHDEV_OBJ_PORT_MDB(obj));
 		break;
 	case SWITCHDEV_OBJ_ID_PORT_VLAN:
-		err = dsa_slave_vlan_add(dev, obj);
+		err = dsa_slave_vlan_add(dev, obj, extack);
 		break;
 	default:
 		err = -EOPNOTSUPP;