[PATCH net v2 0/2] net: dsa: realtek: rtl8365mb: fix FDB lookups in VLAN-unaware bridges

[Stijn Cleynhens <stijncleynhens@gmail.com>]

In a VLAN-unaware bridge, DSA installs FDB and MDB entries with VID 0,
but the switch classifies untagged frames to the bridge PVID and looks up
VID 0 by FID, while the driver installs IVL entries. Nothing matches, so
a station that roams from behind a user port to behind the CPU port (a
Wi-Fi client moving between access points) stays unreachable until the
learned entry ages out.

Patch 1 makes VID 0 use IVL; patch 2 depends on it. Patch 2 keeps the
neutral PVID (VID 0) on ports of a VLAN-unaware bridge and only programs
the bridge PVID while the port filters VLANs. Tagged frames in a
VLAN-unaware bridge are not covered, see patch 2.

Tested on OpenWrt's 6.18 kernel, which carries the rtl8365mb backports up
to v7.4; the code these patches touch is the same as in net. A station
learned behind the uplink that moves behind the CPU port answers 10/10
pings, its learned entry replaced by the CPU one, with VLAN filtering
switched off at runtime: on an RTL8367S (TP-Link Deco X50-Outdoor), and
on an RTL8367S-VB (Deco X50-PoE, with the family D series applied and a
family D branch in rtl8365mb_vlan_pvid_port_commit()), where it also
passes with VLAN filtering on. Before these patches the RTL8367S
answered 0/10. Both patches build without warnings with W=1 C=1.

Note for Mieczyslaw's RTL8367S-VB series in net-next (v8): patch 2
replaces rtl8365mb_vlan_pvid_port_set() and
rtl8365mb_vlan_pvid_port_clear() with rtl8365mb_vlan_pvid_port_commit(),
which gets the target VID (0 for the neutral PVID) and the filtering
state. The family D paths that series adds to set and clear become one
branch there that writes the PVID register and the frame filter from
those two inputs. Happy to send that as a follow-up once both are in.

Changes in v2:
- Patch 1: add Alvin's Reviewed-by.
- Patch 2: replace rtl8365mb_vlan_pvid_port_set() and
  rtl8365mb_vlan_pvid_port_clear() with rtl8365mb_vlan_pvid_port_commit(),
  which is now the only place that sets the frame filter;
  rtl8365mb_port_vlan_filtering() no longer does (Alvin).
- Patch 2: one variable per declaration and an explicit else (Alvin).
- Patch 2: commit message: say what "the VID of the bridge entries" is
  and that the per-bridge EFID keeps lookups local (Alvin).
- v1: https://lore.kernel.org/netdev/20261104082514.2139278-1-stijncleynhens@gmail.com/

Stijn Cleynhens (2):
  net: dsa: realtek: rtl8365mb: use IVL in VLAN 0
  net: dsa: realtek: rtl8365mb: keep the neutral PVID in VLAN-unaware
    bridges

 drivers/net/dsa/realtek/rtl8365mb_main.c | 157 ++++++++-------
 drivers/net/dsa/realtek/rtl8365mb_vlan.c | 233 ++++++++++-------------
 drivers/net/dsa/realtek/rtl8365mb_vlan.h |   7 +-
 3 files changed, 191 insertions(+), 206 deletions(-)


base-commit: 787268686c64be60023743b527645a907e38ccca
-- 
2.56.0