From mboxrd@z Thu Jan  1 00:00:00 1970
From: Chris Wright <chrisw-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [PATCH net-next 4/7] openvswitch: Reset upper layer
 protocol info on internal devices.
Date: Tue, 4 Sep 2012 11:23:04 -0700
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	David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
To: Jesse Gross <jesse-l0M0P4e3n4LQT0dZR+AlfA@public.gmane.org>
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* Jesse Gross (jesse-l0M0P4e3n4LQT0dZR+AlfA@public.gmane.org) wrote:
> On Mon, Sep 3, 2012 at 6:00 PM, David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org> wrote:
> > From: Jesse Gross <jesse-l0M0P4e3n4LQT0dZR+AlfA@public.gmane.org>
> > Date: Mon, 3 Sep 2012 17:57:39 -0700
> >
> >> On Fri, Jul 20, 2012 at 3:26 PM, Jesse Gross <jesse-l0M0P4e3n4LQT0dZR+AlfA@public.gmane.org> wrote:
> >>> It's possible that packets that are sent on internal devices (from
> >>> the OVS perspective) have already traversed the local IP stack.
> >>> After they go through the internal device, they will again travel
> >>> through the IP stack which may get confused by the presence of
> >>> existing information in the skb. The problem can be observed
> >>> when switching between namespaces. This clears out that information
> >>> to avoid problems but deliberately leaves other metadata alone.
> >>> This is to provide maximum flexibility in chaining together OVS
> >>> and other Linux components.
> >>>
> >>> Signed-off-by: Jesse Gross <jesse-l0M0P4e3n4LQT0dZR+AlfA@public.gmane.org>
> >>
> >> It was recently discovered that the bug that this patch fixes is
> >> causing problems in the real world.  Can you please queue this for
> >> stable in 3.4/3.5?  It's currently in Linus's tree as
> >> 7fe99e2d434eafeac0c57b279a77e5de39212636.
> >>
> >
> > What vendor is shipping openvswitch enabled and requires the fix to
> > be in -stable before they'll ship it to customers?
> >
> > That goes into what is 'real world'
> 
> Fedora is running into it I believe.  Chris Wright asked for it so he
> might be able to elaborate more on their plans.

I've not hit the bug myself, but been made aware of the issue from
OpenStack/Quantum folks.

There's a testing scenario that hits this as described in this launchpad
bug:

  https://bugs.launchpad.net/quantum/+bug/1044318

thanks,
-chris