Re: [RFC PATCH net-next 3/5] net: dsa: tag_rtl8_4: add realtek 8 byte protocol 4 tag

[Vladimir Oltean]

On Sun, Aug 22, 2021 at 11:37:28PM +0000, Alvin Šipraga wrote:
> >>>> +	skb->offload_fwd_mark = 1;
> >>>
> >>> At the very least, please use
> >>>
> >>> 	dsa_default_offload_fwd_mark(skb);
> >>>
> >>> which does the right thing when the port is not offloading the bridge.
> >>
> >> Sure. Can you elaborate on what you mean by "at the very least"? Can it
> >> be improved even further?
> >
> > The elaboration is right below. skb->offload_fwd_mark should be set to
> > zero for packets that have been forwarded only to the host (like packets
> > that have hit a trapping rule). I guess the switch will denote this
> > piece of info through the REASON code.
>
> Yes, I think it will be communicated in REASON too. I haven't gotten to
> deciphering the contents of this field since it has not been needed so
> far: the ports are fully isolated and all bridging is done in software.

In that case, setting skb->offload_fwd_mark to true is absolutely wrong,
since the bridge is told that no software forwarding should be done
between ports, as it was already done in hardware (see nbp_switchdev_allowed_egress).

I wonder how this has ever worked? Are you completely sure that bridging
is done in software?