[PATCH net 1/1] net: stmmac: Prevent DSA tags from breaking COE

[Linus Walleij]

On Tue, Dec 19, 2023 at 2:07 PM Maxime Chevallier
<maxime.chevallier at bootlin.com> wrote:

> So it looks like an acceptable solution would be something along the
> lines of what Linus is suggesting here :
>
> https://lore.kernel.org/netdev/20231216-new-gemini-ethernet-regression-v2-2-64c269413dfa@linaro.org/
>
> If so, maybe it's worth adding a new helper for that check ?

Yeah it's a bit annoying when skb->protocol is not == ethertype of buffer.

I can certainly add a helper such as skb_eth_raw_ethertype()
to <linux/if_ether.h> that will inspect the actual ethertype in
skb->data.

It's the most straight-forward approach.

We could also add something like bool custom_ethertype; to
struct sk_buff and set that to true if the tagger adds a custom
ethertype. But I don't know how the network developers feel about
that.

Yours,
Linus Walleij