Re: [PATCH net V2] net: bridge: br_fdb_external_learn_add(): always set EXT_LEARN

On Tue, Sep 03, 2024 at 10:19:57AM +0200, Jonas Gorski wrote:

When userspace wants to take over a fdb entry by setting it as
EXTERN_LEARNED, we set both flags BR_FDB_ADDED_BY_EXT_LEARN and
BR_FDB_ADDED_BY_USER in br_fdb_external_learn_add().

If the bridge updates the entry later because its port changed, we clear
the BR_FDB_ADDED_BY_EXT_LEARN flag, but leave the BR_FDB_ADDED_BY_USER
flag set.

If userspace then wants to take over the entry again,
br_fdb_external_learn_add() sees that BR_FDB_ADDED_BY_USER and skips
setting the BR_FDB_ADDED_BY_EXT_LEARN flags, thus silently ignores the
update.

Fix this by always allowing to set BR_FDB_ADDED_BY_EXT_LEARN regardless
if this was a user fdb entry or not.

Fixes: 710ae7287737 ("net: bridge: Mark FDB entries that were added by user as such")
Signed-off-by: Jonas Gorski <redacted>

Reviewed-by: Ido Schimmel <idosch@nvidia.com>