bogus 0 len IP packet, was: Hang in VOP_LOCK1_APV on 8-STABLE with NFS.

[Pyun YongHyeon]

On Tue, Jan 18, 2011 at 07:35:30PM +0100, sthaug at nethelp.no wrote:
> > > I'm seeing the same problem with Broadcom NetXtreme (bce) cards:
> > > 
> > > bce0 at pci0:3:0:0:        class=0x020000 card=0x03421014 chip=0x164c14e4 rev=0x12 hdr=0x00
> > >     vendor     = 'Broadcom Corporation'
> > >     device     = 'Broadcom NetXtreme II Gigabit Ethernet Adapter (BCM5708)'
> > >     class      = network
> > >     subclass   = ethernet
> > > 
> > > This is with 8.2-PRERELEASE. Turning off TSO (ifconfig bce0 -tso)
> > > removes the problem.
> > > 
> > 
> > Is there a reliable way to trigger this on bce(4)? I don't have
> > BCM5708 but I have BCM5709 so I can verify that.
> 
> It showed up pretty much immediately when running a csup sessions
> against cvsup2.us.freebsd.org.
> 
> I have a pcap file from the session, if you're interested.
> 

I vaguely guess upper stack might pass less than MSS sized segment
to TSO capable driver with CSUM_TSO.
How about merging r212803 to stable/8?

> Steinar Haug, Nethelp consulting, sthaug at nethelp.no