Date:	Sun, 24 Mar 2013 02:41:25 +0100
From:	Hannes Frederic Sowa <hannes@...essinduktion.org>
To:	Sven Hartge <sven@...nhartge.de>
Cc:	netdev@...r.kernel.org, Jie.Yang@...eros.com,
	xiong.huang@...eros.com
Subject: Re: Atheros Communications Inc. AR8121/AR8113/AR8114 Gigabit or Fast Ethernet (rev b0) 1.0.0.7 md5/sha1 corrupted using NFS and samba (updated) Version 2

On Sun, Mar 24, 2013 at 02:35:11AM +0100, Sven Hartge wrote:
> Hannes Frederic Sowa <hannes@...essinduktion.org> wrote:
> > On Sun, Mar 24, 2013 at 01:36:33AM +0100, Sven Hartge wrote:
> >> Hannes Frederic Sowa <hannes@...essinduktion.org> wrote:
> >> > On Sat, Mar 23, 2013 at 12:54:25AM -0400, rebelyouth wrote:
> >> >> I applied your patch on my the kernel 3.7.9 and look like the patch do 
> >> >> what you said before :
> >> >> 
> >> >> "This does not solve the real problem, which I have not yet understood 
> >> >> (wrong packets will be discarded now and will be hopefully resend). "
> >> >> 
> >> >> There are errors on the RX side of the server and the speed is 5~10% 
> >> >> less but the files are ok in nfsv4 , SFTP/FTP and samba.
> >> >> 
> >> >> Maybe the Atheros drivers for windows had a patch for the checksum 
> >> >> already in the drivers and the chipset  have some hardware bug, but for 
> >> >> me your patch is already an achievement and I really thank you for your 
> >> >> time and consideration.
> >> 
> >> > The upstream driver (which is a tarball I found with google
> >> > AR81Family-linux-v1.0.1.14.tar.gz) has this function ifdefed out. I have
> >> > a couple of more things I want to test as soon as I have access to the
> >> > hardware again.  If I don't find a better solution I will submit a patch
> >> > which disables rx checksumming as a whole for inclusion to net-next.
> >> 
> >> I remember having the some problem with an atl1e chip on my Asus
> >> PQ5-Pro. It would corrupt ethernet frames, resulting in dropped
> >> connections when using SSH (bailing out with a HMAC crypto error) etc.
> >> 
> >> After some conversations with an Atheros engineer (Jie Yang
> >> <Jie.Yang@...eros.com>) I got the following patch, which I applied for
> >> some time to my local Debian kernel packages. It fixed the problem for
> >> me, until I switched the board to a newer one.
> >> 
> >> As far as I understand, this patch rips out any checksumming function
> >> and just advertises the chip as not using and providing any.
> 
> > Yes, my patch does the same, just jumpes over the body of the function
> > and returns without updating the ip_summed field.
> 
> >> My mail archive indicates, this bug has been fixed in the upstream atl1e
> >> driver since version l1c-linux-v1.0.0.11-test.tar.gz.
> 
> > Yes, they ifdefed out the body of the function.
> 
> > What we have found so far:
> 
> > It seems packet content overwrites itself. We have not yet found a
> > pattern but it seems that some 16 bytes from the payload overwrite
> > other parts of the packet, even mulitple times (but the same 16 bytes
> > though).
> 
> > I also checked freebsd. Hardware rx checksumming is disabled there and
> > we did not see any checksum errors in the stack. So I assume they
> > don't have this problem.
> 
> I understand from my conversation with Jie Yang, that he reproduced the
> problem at Atheros and then decided to disable checksumming in the
> driver. My guess would be that is some kind of confirmation this feature
> is broken in that hardware and should not be used.

Added Jie Yang and Xiong Huang to Cc.

I don't know if checksumming is the cause of this problem. Perhaps the dma
transfers get corrupted and the data was correct in the card's buffers.

Greetings,

  Hannes

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