6-CURRENT Network stack issues w/SMP? (Was: Re: TreeListfailed: Network write failure: ChannelMux.ProtocolError)

Robert Watson rwatson at FreeBSD.ORG
Sun Sep 12 07:57:58 PDT 2004

On Sun, 12 Sep 2004, Andre Guibert de Bruet wrote:

> On Sun, 12 Sep 2004, Kris Kennaway wrote:
> > On Sun, Sep 12, 2004 at 02:42:03AM -0400, Andre Guibert de Bruet wrote:
> >
> >>> I've also noticed data corruption in the form of failed CRCs (And hence
> >>> dropped SSH connections) while transferring large amounts of data via SSH
> >>> over gige to a machine on its subnet. These problems started occuring
> >>> after the giant-less networking megacommit. Older kernels check out
> >>> without any such issues.
> >
> > Does it go away if you turn off debug.mpsafenet?  If not, it's
> > probably not related to that commit.
> Setting debug.mpsafenet to 0 allows the SSH transfers to complete. The
> MD5 checksums and sizes match. Where do we go from here? 

I think I'd look at the following next:

- Does your network interface driver support checksum offload?  If so,
  what happens if you disable that?

- Is the network interface driver marked as INTR_MPSAFE and/or not
  IFF_NEEDSGIANT.  If either, try setting the driver to run with Giant by
  removing INTR_MPSAFE and adding IFF_NEEDSGIANT.

After that I think we want to try and produce a non-SSH reproduction
scenario using a very simple test program...

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert at fledge.watson.org      Principal Research Scientist, McAfee Research

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