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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Tue, 29 Jun 2021 21:18:09 +0200
From:   Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
To:     Jesper Dangaard Brouer <jbrouer@...hat.com>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        Alexander Duyck <alexander.duyck@...il.com>,
        Lorenzo Bianconi <lorenzo@...nel.org>,
        bpf <bpf@...r.kernel.org>, Netdev <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, shayagr@...zon.com,
        "Jubran, Samih" <sameehj@...zon.com>,
        John Fastabend <john.fastabend@...il.com>,
        David Ahern <dsahern@...nel.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Eelco Chaudron <echaudro@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Saeed Mahameed <saeed@...nel.org>,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>,
        "Karlsson, Magnus" <magnus.karlsson@...el.com>,
        Tirthendu <tirthendu.sarkar@...el.com>
Subject: Re: [PATCH v9 bpf-next 01/14] net: skbuff: add data_len field to
 skb_shared_info

> 
> 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@...nel.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?

Regards,
Lorenzo

Download attachment "signature.asc" of type "application/pgp-signature" (229 bytes)