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Message-ID: [ref]
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.
From: Eric Dumazet <redacted>
To: Sander Eikelenboom <redacted>
Cc: Zoltan Kiss <redacted>, Ian Campbell
 [off-list ref],  "David S. Miller" [off-list ref],
 netdev@vger.kernel.org, xen-devel@lists.xen.org, Neal Cardwell
 [off-list ref]
Date: Fri, 02 May 2014 08:35:33 -0700
In-Reply-To: [ref]
References: [ref]
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On Thu, 2014-05-01 at 17:40 +0200, Sander Eikelenboom wrote:

quoted

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 )

I applied the patch from the thread above, but i still can't get it to work.

Hmm i'm trying to do it client-server over the bridge, since that is what i 
would like to test and from what i read from the sparse documentation that 
should be possible:

So on the xen guest (that is on a bridge) i run:
./packetdrill --wire_server

And on the host (dom0):
./packetdrill  -v --wire_client --wire_server_ip=192.168.1.9 --ip_version=ipv4  test-file

Only reaction i get is on the guest:
inbound injected packet:  0.100252 S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7>

But nothing more seems to happen after that, the test doesn't complete or return, but i also don't 
see any more traffic on the port (8081) used by packetdrill on the guest.

--
Sander