Intel 82550 Pro/100 Ethernet and TSO troubles

[YongHyeon PYUN]

On Wed, Dec 14, 2011 at 01:32:42PM -0800, YongHyeon PYUN wrote:
> On Wed, Dec 14, 2011 at 10:17:41PM +0100, Andrea Venturoli wrote:
> > On 12/14/11 20:59, YongHyeon PYUN wrote:
> > 
> > >AFAIK the firmware of controller has no known TSO issue so it
> > >indicates a bug in driver.
> > >What makes me wonder is ICMP ECHO packet should not be affected by
> > >TSO and I have no clue at this moment.
> > 
> > I wasn't talking about ICMP ECHO.
> > 
> > What happened was:
> > a) the client connected to my server, advertising a TCP MSS of X;
> > b) my server started sending with packets larger than X (possibly it 
> > misinterpreted MSS size???);
> > c) an ICMP packet arrived, asking my server to send packets no larger 
> > than Y (I guess it was ignored);
> > d) my server kept resending the same (too big) packets;
> > e) it eventually reduced packet size, but it was still larger than Y;
> > ...
> > 
> > Wireshark showed some wrong checksums (I believe on the ICMP packet, but 
> > I might remember wrong).
> 
> You can check whether you received bad checksummed frames with
> netstat(1).
> 
> > Of course this made a bell ring and removing TSO solved everything.
> > 
> > 
> > 
> > >(Here, I assume you've
> > >captured packets on receiver side since bpf sees packets before
> > >hardware computes checksum.)
> > 
> > Yes, although I don't have them anymore.
> > 
> > 
> > 
> > >If you have a reliable way that reproduces the issue, let me know.
> > 
> > I can turn TSO on again, save the packets and send them to you.
> > I just hope nothing changes on the Internet in between the server and 
> > the client.
> > Let me know if you need/want this and I'll arrange in the next few days.
> > 
> 
> Let me know MSS of both client and server.
> Is simple downloading from client to server is enough to trigger
> the issue?  Packet capture that shows the problem would be great to
> know what's going on here.
> 

Would you try attached patch and let me know it goes?
-------------- next part --------------
A non-text attachment was scrubbed...
Name: fxp.tso.diff
Type: text/x-diff
Size: 484 bytes
Desc: not available
Url : http://lists.freebsd.org/pipermail/freebsd-net/attachments/20111214/ecf1e3b0/fxp.tso.bin