kernel: DSA roaming fix for Marvell mv88e6xxx

Marvell mv88e6xxx switch series cannot perform MAC learning from
CPU-injected (FROM_CPU) DSA frames, which results in 2 issues.
- excessive flooding, due to the fact that DSA treats those addresses
as unknown
- the risk of stale routes, which can lead to temporary packet loss

Backport those patch series from netdev mailing list, which solve these
issues by adding and clearing static entries to the switch's FDB.

Add a hack patch to set default VID to 1 in port_fdb_{add,del}. Otherwise
the static entries will be added to the switch's private FDB if VLAN
filtering disabled, which will not work.

The switch may generate an "ATU violation" warning when a client moves
from the CPU port to a switch port because the static ATU entry added by
DSA core still points to the CPU port. DSA core will then clear the static
entry so it is not fatal. Disable the warning so it will not confuse users.

Link: https://lore.kernel.org/netdev/20210106095136.224739-1-olteanv@gmail.com/
Link: https://lore.kernel.org/netdev/20210116012515.3152-1-tobias@waldekranz.com/
Ref: https://gitlab.nic.cz/turris/turris-build/-/issues/165
Signed-off-by: DENG Qingfang <dqfext@gmail.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/target/linux/generic/backport-5.4/771-v5.12-net-dsa-be-louder-when-a-non-legacy-FDB-operation-fa.patch b/target/linux/generic/backport-5.4/771-v5.12-net-dsa-be-louder-when-a-non-legacy-FDB-operation-fa.patch
new file mode 100644
index 0000000000..967502f022
--- /dev/null
+++ b/target/linux/generic/backport-5.4/771-v5.12-net-dsa-be-louder-when-a-non-legacy-FDB-operation-fa.patch
@@ -0,0 +1,52 @@
+From 2fd186501b1cff155cc4a755c210793cfc0dffb5 Mon Sep 17 00:00:00 2001
+From: Vladimir Oltean <vladimir.oltean@nxp.com>
+Date: Wed, 6 Jan 2021 11:51:31 +0200
+Subject: [PATCH] net: dsa: be louder when a non-legacy FDB operation fails
+
+The dev_close() call was added in commit c9eb3e0f8701 ("net: dsa: Add
+support for learning FDB through notification") "to indicate inconsistent
+situation" when we could not delete an FDB entry from the port.
+
+bridge fdb del d8:58:d7:00:ca:6d dev swp0 self master
+
+It is a bit drastic and at the same time not helpful if the above fails
+to only print with netdev_dbg log level, but on the other hand to bring
+the interface down.
+
+So increase the verbosity of the error message, and drop dev_close().
+
+Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
+Reviewed-by: Andrew Lunn <andrew@lunn.ch>
+Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
+Signed-off-by: Jakub Kicinski <kuba@kernel.org>
+---
+ net/dsa/slave.c | 10 +++++++---
+ 1 file changed, 7 insertions(+), 3 deletions(-)
+
+--- a/net/dsa/slave.c
++++ b/net/dsa/slave.c
+@@ -1590,7 +1590,9 @@ static void dsa_slave_switchdev_event_wo
+ 
+ 		err = dsa_port_fdb_add(dp, fdb_info->addr, fdb_info->vid);
+ 		if (err) {
+-			netdev_dbg(dev, "fdb add failed err=%d\n", err);
++			netdev_err(dev,
++				   "failed to add %pM vid %d to fdb: %d\n",
++				   fdb_info->addr, fdb_info->vid, err);
+ 			break;
+ 		}
+ 		fdb_info->offloaded = true;
+@@ -1605,9 +1607,11 @@ static void dsa_slave_switchdev_event_wo
+ 
+ 		err = dsa_port_fdb_del(dp, fdb_info->addr, fdb_info->vid);
+ 		if (err) {
+-			netdev_dbg(dev, "fdb del failed err=%d\n", err);
+-			dev_close(dev);
++			netdev_err(dev,
++				   "failed to delete %pM vid %d from fdb: %d\n",
++				   fdb_info->addr, fdb_info->vid, err);
+ 		}
++
+ 		break;
+ 	}
+ 	rtnl_unlock();