Re: [PATCH net-next v2 3/3] tun: AF_XDP Tx zero-copy support

[Willem de Bruijn]

Maciej Fijalkowski wrote:
> On Wed, Feb 28, 2024 at 07:05:56PM +0800, Yunjian Wang wrote:
> > This patch set allows TUN to support the AF_XDP Tx zero-copy feature,
> > which can significantly reduce CPU utilization for XDP programs.
> 
> Why no Rx ZC support though? What will happen if I try rxdrop xdpsock
> against tun with this patch? You clearly allow for that.

This is AF_XDP receive zerocopy, right?

The naming is always confusing with tun, but even though from a tun
PoV this happens on ndo_start_xmit, it is the AF_XDP equivalent to
tun_put_user.

So the implementation is more like other device's Rx ZC.

I would have preferred that name, but I think Jason asked for this
and given tun's weird status, there is something bo said for either.