Re: [RFC PATCH v2 net-next 15/16] net: dsa: return -EOPNOTSUPP when driver does not implement .port_lag_join

From: Tobias Waldekranz
Date: Mon Mar 22 2021 - 11:59:12 EST

On Fri, Mar 19, 2021 at 01:18, Vladimir Oltean <olteanv@xxxxxxxxx> wrote:
> From: Vladimir Oltean <vladimir.oltean@xxxxxxx>
> The DSA core has a layered structure, and even though we end up
> returning 0 (success) to user space when setting a bonding/team upper
> that can't be offloaded, some parts of the framework actually need to
> know that we couldn't offload that.
> For example, if dsa_switch_lag_join returns 0 as it currently does,
> dsa_port_lag_join has no way to tell a successful offload from a
> software fallback, and it will call dsa_port_bridge_join afterwards.
> Then we'll think we're offloading the bridge master of the LAG, when in
> fact we're not even offloading the LAG. In turn, this will make us set
> skb->offload_fwd_mark = true, which is incorrect and the bridge doesn't
> like it.
> Signed-off-by: Vladimir Oltean <vladimir.oltean@xxxxxxx>
> ---

Reviewed-by: Tobias Waldekranz <tobias@xxxxxxxxxxxxxx>