On 9/3/24 11:19, 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 <jonas.gorski@xxxxxxxx>
> ---
> Changelog:
> V2:
> * always allow setting EXT_LEARN regardless if user entry
> * reworded the commit message a bit to match the new behavior
> * dropped the redundant code excerpt from the commit message as it's
> already in the context
>
> net/bridge/br_fdb.c | 6 ++----
> 1 file changed, 2 insertions(+), 4 deletions(-)
>
> diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
> index c77591e63841..ad7a42b505ef 100644
> --- a/net/bridge/br_fdb.c
> +++ b/net/bridge/br_fdb.c
> @@ -1469,12 +1469,10 @@ int br_fdb_external_learn_add(struct net_bridge *br, struct net_bridge_port *p,
> modified = true;
> }
>
> - if (test_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags)) {
> + if (test_and_set_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags)) {
> /* Refresh entry */
> fdb->used = jiffies;
> - } else if (!test_bit(BR_FDB_ADDED_BY_USER, &fdb->flags)) {
> - /* Take over SW learned entry */
> - set_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags);
> + } else {
> modified = true;
> }
>
Although the curly braces aren't needed, I don't mind in this case.
Acked-by: Nikolay Aleksandrov <razor@xxxxxxxxxxxxx>
