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

On 1/13/20 2:28 AM, Vladimir Oltean wrote:

On Mon, 13 Jan 2020 at 11:46, Alexander Lobakin [off-list ref] wrote:

quoted

Vladimir Oltean wrote 13.01.2020 12:42:

quoted

Hi Alexander,

On Mon, 13 Jan 2020 at 11:22, Alexander Lobakin [off-list ref]
wrote:

quoted

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.
-- 
Florian

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