netdev - Re: [3.15-rc3] Bisected: xen-netback mangles packets between two guests on a bridge since merge of "TX grant mapping with SKBTX_DEV

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Message-ID: <1399044933.29914.242.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Fri, 02 May 2014 08:35:33 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Sander Eikelenboom <linux@...elenboom.it>
Cc:	Zoltan Kiss <zoltan.kiss@...rix.com>,
	Ian Campbell <Ian.Campbell@...rix.com>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	xen-devel@...ts.xen.org, Neal Cardwell <ncardwell@...gle.com>
Subject: Re: [3.15-rc3] Bisected: xen-netback mangles packets between two
 guests on a bridge since merge of "TX grant mapping with SKBTX_DEV_ZEROCOPY
 instead of copy" series.

On Thu, 2014-05-01 at 17:40 +0200, Sander Eikelenboom wrote:

> Yesterday i tried to get packetdrill (https://code.google.com/p/packetdrill/) to 
> work to see if i could reproduce with one of it's tests, but didn't get the 
> client server stuff working. It seems it has helped with finding and fixing 
> previous kernel networking bugs.

If you use recent net-next kernel, you need a packetdrill patch, Neal
might submit it shortly on packetdrill repo.

packetdrill currently does not consume the packets sent on the tun
device, so this triggers the new [1] TCP stack behavior detecting packet
did not yet leaved the host.

[1] :
( http://git.kernel.org/cgit/linux/kernel/git/davem/net-next.git/commit/?id=1f3279ae0c13cd742731726b0ed195d5f09b14e4 )



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