Intel 82550 Pro/100 Ethernet and TSO troubles

[YongHyeon PYUN]

On Wed, Dec 14, 2011 at 03:22:06PM -0800, YongHyeon PYUN wrote:
> 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?

Sorry, it seems extra pull up for TCP payload may not be required
here.  Try this instead.
-------------- next part --------------
Index: sys/dev/fxp/if_fxp.c
===================================================================
--- sys/dev/fxp/if_fxp.c	(revision 228504)
+++ sys/dev/fxp/if_fxp.c	(working copy)
@@ -1454,7 +1454,7 @@
 			return (ENOBUFS);
 		}
 		tcp = (struct tcphdr *)(mtod(m, char *) + poff);
-		m = m_pullup(m, poff + sizeof(struct tcphdr) + tcp->th_off);
+		m = m_pullup(m, poff + (tcp->th_off << 2));
 		if (m == NULL) {
 			*m_head = NULL;
 			return (ENOBUFS);