[Intel-wired-lan] [net PATCH 0/2] Don't use lco_csum to compute IPv4 checksum
Stephen Rothwell
sfr at canb.auug.org.au
Wed Jan 11 23:19:29 UTC 2017
Hi Dave,
On Tue, 29 Nov 2016 20:07:08 +1100 Stephen Rothwell <sfr at canb.auug.org.au> wrote:
>
> Hi Jeff,
>
> On Tue, 29 Nov 2016 10:43:04 +1100 Stephen Rothwell <sfr at canb.auug.org.au> wrote:
> >
> > On Mon, 28 Nov 2016 14:26:02 -0800 Jeff Kirsher <jeffrey.t.kirsher at intel.com> wrote:
> > >
> > > On Mon, 2016-11-28 at 10:42 -0500, Alexander Duyck wrote:
> > > > When I implemented the GSO partial support in the Intel drivers I was
> > > > using
> > > > lco_csum to compute the checksum that we needed to plug into the IPv4
> > > > checksum field in order to cancel out the data that was not a part of the
> > > > IPv4 header. However this didn't take into account that the transport
> > > > offset might be pointing to the inner transport header.
> > > >
> > > > Instead of using lco_csum I have just coded around it so that we can use
> > > > the outer IP header plus the IP header length to determine where we need
> > > > to
> > > > start our checksum and then just call csum_partial ourselves.
> > > >
> > > > This should fix the SIT issue reported on igb interfaces as well as
> > > > simliar
> > > > issues that would pop up on other Intel NICs.
> > > >
> > > > ---
> > > >
> > > > Alexander Duyck (2):
> > > > igb/igbvf: Don't use lco_csum to compute IPv4 checksum
> > > > ixgbe/ixgbevf: Don't use lco_csum to compute IPv4 checksum
> > >
> > > Stephen, I have applied Alex's patches to my net-queue tree. Can you
> > > confirm they resolve the bug seen?
> >
> > Its a bit tricky because the origin problem only happens on my
> > production server (ozlabs.org), but I will see if I can manage to just
> > remove and reload the driver ... though, the server is running a 4.7.8
> > kernel and I am wondering how well these patches will apply?
>
> We have a winner! This fixes my problem, so I can run at full speed
> with gso and tso enabled in the sit interface and tx-gso-partial
> enabled on the underlying ethernet.
>
> Thanks to everyone for diagnosis and solution.
>
> It would be nice if this fix went into the stable kernels as well so it
> will turn up in the distro kernels eventually.
It looks like these 2 commits:
516165a1e2f2 igb/igbvf: Don't use lco_csum to compute IPv4 checksum
c54cdc316dbd ixgbe/ixgbevf: Don't use lco_csum to compute IPv4 checksum
have not been sent to stable. They fix a bug introduced in v4.7-rc1
and so need to go into 4.7 and 4.8 stable trees.
--
Cheers,
Stephen Rothwell
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