Re: mpd client timeouts (bisected) 2.6.35-rc3

From: markus@xxxxxxxxxxxxxxx
Date: Sun Jun 13 2010 - 16:59:31 EST

On Sun, Jun 13, 2010 at 01:36:30PM -0700, John Fastabend wrote:
> John Fastabend wrote:
> >David Miller wrote:
> >>From: Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx>
> >>Date: Sat, 12 Jun 2010 12:28:02 +0200
> >>
> >>>Commit 597a264b1a9c7e36d1728f677c66c5c1f7e3b837:
> >>>»net: deliver skbs on inactive slaves to exact matches«
> >>>
> >>>causes large timeouts when mpd clients try to connect to a locally
> >>>running mpd (music player demon) on my machine. This makes it
> >>>impossible to control mpd.
> >>>
> >>>I bisected this down to the commit mentioned above.
> >>>Reverting the commit from 2.6.35-rc3 also solves the problem.
> >>John, find an easy and fast way to fix this or else I am
> >>going to revert.
> >>
> >>Thanks.
> >
> >Looks like skbs are hitting loopback_xmit() with deliver_no_wcard
> >set. Then in the receive path these skbs are only delivered to
> >exact matches. Not sure why this bit is set here, I'll track this
> >down first thing tomorrow.
> >
> >Thanks,
> >John.
> >--
> Needed to set the wcard bit in copy_skb_header otherwise it will not
> be cleared when called from skb_clone. Which then hits the loopback
> device gets pushed into the rx path and is eventually dropped. The
> following patch fixes this. Hopefully, this is easy and fast enough
> for you Dave.
> [PATCH] net: fix deliver_no_wcard regression on loopback device

This solves the problem here. Thanks.

Tested-by: Markus Trippelsdorf <markus@xxxxxxxxxxxxxxx>
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