netdev - Re: [PATCH] Reorder ACK/RST checking in LISTEN state

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Message-Id: <20080212.230824.263037704.davem@davemloft.net>
Date:	Tue, 12 Feb 2008 23:08:24 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	katterjohn@...il.com
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH] Reorder ACK/RST checking in LISTEN state

From: Kris Katterjohn <katterjohn@...il.com>
Date: Wed, 13 Feb 2008 00:38:13 -0600

> I've attached a patch that changes the order of the ACK and RST checking 
> in the LISTEN state in tcp_rcv_state_process() in tcp_input.c
> 
> Before:  If an ACK/RST packet is received, then tcp_rcv_state_process() 
> would return 1 because of the ACK.  Then (following the function calls 
> in tcp_ipv4.c and tcp_minisocks.c), tcp_v4_send_reset() is called--but 
> since there is a RST in the packet it just returns.  After this, the 
> kfree_skb() is called.  The same goes in tcp_ipv6.c as well.
> 
> But if the order of the ACK and RST checking is reversed, __kfree_skb() 
> is called in tcp_rcv_state_process() because of the RST and the function 
> returns 0, which skips that other useless stuff.
> 
> This is the order specified on page 65 of RFC 793 anyway.
> 
> Signed-off-by: Kris Katterjohn <katterjohn@...il.com>

This code has been like this for I don't know how many years,
the end result is the same both before and after your patch,
and the added expense of the existing code is frankly trivial.

I really don't want to apply this, it doesn't buy us anything,
sorry.
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