Re: e100 REGRESSION in 2.6.32

From: Roger Oksanen
Date: Wed Dec 16 2009 - 15:47:47 EST


On Wednesday 16 December 2009 21:50:38 Alan Stern wrote:
> On Wed, 16 Dec 2009, Brandeburg, Jesse wrote:
> > Alan thanks for the report, I wonder if
> > you can revert 98468efddb101f8a29af974101c17ba513b07be1 and see if that
> > fixes it?
>
> It does indeed. Thanks for the quick response.
>
> > Roger on the To: line made that change, which may have broken e100 for
> > your system.
>
> It looks simple enough, but obviously something is wrong with it.

I'm looking into this. Quite a baffling problem though. I have no idea what
causes the last 4 bytes to change slightly (6c 6b 6b a3). Perhaps the patch
only changed the timings to uncloak a lurking bug..
struct sk_buff has users as it's last member, so perhaps there is a preempt
point in dmapool that triggers a race with the rx path.

I'll try to reproduce this..

--
Roger Oksanen <roger.oksanen@xxxxxxxxxxxxxx>
http://www.cs.helsinki.fi/u/raoksane
+358 50 355 1990
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