On Thu, 1 Aug 2019 10:18:49 +0200
Jesper Dangaard Brouer <brouer@xxxxxxxxxx> wrote:
[...]
> Cc. Stephen as this might be related to:
> commit 458bf2f224f0 ("net: core: support XDP generic on stacked devices.") (Author: Stephen Hemminger).
>
> On Wed, 31 Jul 2019 21:12:23 +0000 Brandon Cazander <brandon.cazander@xxxxxxxxxxxxxxx> wrote:
>
> > I am having an issue with xdpgeneric specifically when using XDP_PASS after
> > bpf_xdp_adjust_head to pop some headers off. My test environment is qemu using
> > virtio_net specifically, but it also happens with e1000 in qemu/physical devices.
> >
> > On a real NIC (ixgbe), the same program is successfully passing decapsulated
> > traffic, but fails in the same way when forcing xdpgeneric mode.
>
[...]
> > Kernel is 5.2.2-1-debug, OS is openSUSE Tumbleweed 20190724.
>
> Can you test an earlier kernel, specifically before: commit
> 458bf2f224f0 ("net: core: support XDP generic on stacked devices.")
> (Author: Stephen Hemminger)
>
> $ git describe --contains 458bf2f224f04
> v5.2-rc3~26^2~11^2
>
> I fear that this commit, which moved generic-XDP to a later call point,
> might cause this. Because it could be that the SKB network_header
> update, is now done before calling XDP program (... still looking at
> code details).
I now have a reproducer myself, and I can confirm that this commit
458bf2f224f0 ("net: core: support XDP generic on stacked devices.") is
the issue... reverting it fixes the problem. (I don't have a fix yet)
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
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