Bug 593040

Description of problem:

Customer has an application that receives a connection and keeps
receiving data without sending anything back, just pure ACKs. After 
some time receiving periodic data from the client, the server starts 
to send keepalive packets.

The upstream commit fixes this problem:

Date: Mon, 26 Apr 2010 18:33:27 +0000 (+0000)
Subject: TCP: avoid to send keepalive probes if receiving data
X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fdavem%2Fnet-next-2.6.git;a=commitdiff_plain;h=6c37e5de456987f5bc80879afde05aa120784095

TCP: avoid to send keepalive probes if receiving data

RFC 1122 says the following:
...
  Keep-alive packets MUST only be sent when no data or
  acknowledgement packets have been received for the
  connection within an interval.
...

The acknowledgement packet is reseting the keepalive
timer but the data packet isn't. This patch fixes it by
checking the timestamp of the last received data packet
too when the keepalive timer expires.

Signed-off-by: Flavio Leitner <fleitner>
Signed-off-by: Eric Dumazet <eric.dumazet>
Acked-by: Ilpo Järvinen <ilpo.jarvinen>
Signed-off-by: David S. Miller <davem>
---

Version-Release number of selected component (if applicable):
all - including upstream before the commit above

How reproducible:
Always

Steps to Reproduce:
1. Run the server script on one system
2. Run the client script on another system
3. Watch the traffic dump and the time, even after the server had received
   data packet, it will send a keepalive packet.
  
Expected results:
No keepalive sent as the data exchanged proves the connection is alive.

Additional info:
Brew build url with the upstream patch backported and applied:
https://brewweb.devel.redhat.com/taskinfo?taskID=2444536