netdev - Re: [net PATCH 0/2] Don't use lco_csum to compute IPv4 checksum

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Date:   Tue, 29 Nov 2016 10:43:04 +1100
From:   Stephen Rothwell <sfr@...b.auug.org.au>
To:     Jeff Kirsher <jeffrey.t.kirsher@...el.com>
Cc:     netdev@...r.kernel.org, intel-wired-lan@...ts.osuosl.org,
        Alexander Duyck <alexander.h.duyck@...el.com>,
        davem@...emloft.net
Subject: Re: [net PATCH 0/2] Don't use lco_csum to compute IPv4 checksum

Hi Jeff,

On Mon, 28 Nov 2016 14:26:02 -0800 Jeff Kirsher <jeffrey.t.kirsher@...el.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?

-- 
Cheers,
Stephen Rothwell