From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Fri, 19 Mar 2010 05:37:18 +0000 (+0000)
Subject: tcp: Add SNMP counter for DEFER_ACCEPT
X-Git-Tag: v2.6.35-rc1~473^2~725
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=907cdda5205b012eec7513f66713749b293188c9;p=pandora-kernel.git

tcp: Add SNMP counter for DEFER_ACCEPT

Its currently hard to diagnose when ACK frames are dropped because an
application set TCP_DEFER_ACCEPT on its listening socket.

See http://bugzilla.kernel.org/show_bug.cgi?id=15507

This patch adds a SNMP value, named TCPDeferAcceptDrop

netstat -s | grep TCPDeferAcceptDrop
    TCPDeferAcceptDrop: 0

This counter is incremented every time we drop a pure ACK frame received
by a socket in SYN_RECV state because its SYNACK retrans count is lower
than defer_accept value.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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