[PATCH RFC net-next 05/19] net: dsa: tag_ar9331: add GRO callbacks

Florian Fainelli f.fainelli at gmail.com
Tue Jan 14 13:56:11 PST 2020

On 1/13/20 2:28 AM, Vladimir Oltean wrote:
> On Mon, 13 Jan 2020 at 11:46, Alexander Lobakin <alobakin at dlink.ru> wrote:
>> Vladimir Oltean wrote 13.01.2020 12:42:
>>> Hi Alexander,
>>> On Mon, 13 Jan 2020 at 11:22, Alexander Lobakin <alobakin at dlink.ru>
>>> wrote:
>>>> CPU ports can't be bridged anyway
>>>> Regards,
>>>> ᚷ ᛖ ᚢ ᚦ ᚠ ᚱ
>>> The fact that CPU ports can't be bridged is already not ideal.
>>> One can have a DSA switch with cascaded switches on each port, so it
>>> acts like N DSA masters (not as DSA links, since the taggers are
>>> incompatible), with each switch forming its own tree. It is desirable
>>> that the ports of the DSA switch on top are bridged, so that
>>> forwarding between cascaded switches does not pass through the CPU.
>> Oh, I see. But currently DSA infra forbids the adding DSA masters to
>> bridges IIRC. Can't name it good or bad decision, but was introduced
>> to prevent accidental packet flow breaking on DSA setups.
> I just wanted to point out that some people are going to be looking at
> ways by which the ETH_P_XDSA handler can be made to play nice with the
> master's rx_handler, and that it would be nice to at least not make
> the limitation worse than it is by converting everything to
> rx_handlers (which "currently" can't be stacked, from the comments in
> netdevice.h).

I am not sure this would change the situation much, today we cannot have
anything but switch tags travel on the DSA master network device,
whether we accomplish the RX tap through a special skb->protocol value
or via rx_handler, it probably does not functionally matter, but it
could change the performance.

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