Re: [PATCH v9 bpf-next 01/14] net: skbuff: add data_len field to skb_shared_info

Alexander Duyck
2021-06-29T20:45:22Z

On Tue, Jun 29, 2021 at 12:18 PM Lorenzo Bianconi
<lorenzo.bianconi@redhat.com> wrote:
>
> >
> > On 29/06/2021 20.37, Jakub Kicinski wrote:
> > > On Tue, 29 Jun 2021 11:18:38 -0700 Alexander Duyck wrote:
> > > > On Tue, Jun 29, 2021 at 10:08 AM Jakub Kicinski <kuba@kernel.org> wrote:
> > > > > > ack, I agree. I will fix it in v10.
> > > > > Why is XDP mb incompatible with LRO? I thought that was one of the use
> > > > > cases (mentioned by Willem IIRC).
> > > > XDP is meant to be a per packet operation with support for TX and
> > > > REDIRECT, and LRO isn't routable. So we could put together a large LRO
> > > > frame but we wouldn't be able to break it apart again. If we allow
> > > > that then we are going to need a ton more exception handling added to
> > > > the XDP paths.
> > > >
> > > > As far as GSO it would require setting many more fields in order to
> > > > actually make it offloadable by any hardware.
> > > It would require more work, but TSO seems to be explicitly stated
> > > as what the series builds towards (in the cover letter). It's fine
> > > to make choices we'd need to redo later, I guess, I'm just trying
> > > to understand the why.
> >
> > This is also my understanding that LRO and TSO is what this patchset is
> > working towards.
> >
> > Sorry, I don't agree or understand this requested change.
> >
> >
>
> My understanding here is to use gso_size to store paged length of the
> xdp multi-buffer. When converting the xdp_frame to a skb we will need
> to overwrite it to support gro/lro. Is my understanding correct?

Yes, I was thinking just of the xdp_buff, not the xdp_frame. My focus
for right now is mostly around the Rx side of things, xdp_buff to skb,
and around the XDP_TX path. If we want to drop/move where we keep the
data length when doing the conversion I would be fine with that.