netdev - Re: Problem with tcp (2.6.31) as first

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Message-Id: <20091130.125623.44579269.davem@davemloft.net>
Date:	Mon, 30 Nov 2009 12:56:23 -0800 (PST)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	ilpo.jarvinen@...sinki.fi, ole@....pl, herbert@...dor.apana.org.au,
	netdev@...r.kernel.org
Subject: Re: Problem with tcp (2.6.31) as first

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Mon, 30 Nov 2009 10:12:19 +0100

> [PATCH] tcp: tcp_disconnect() should clear window_clamp
> 
> NFS can reuse its TCP socket after calling tcp_disconnect().
> We noticed window scaling was not negotiated in SYN packet of next connection request.
> 
> Fix is to clear tp->window_clamp in tcp_disconnect().
> 
> Reported-by: Krzysztof Oledzki <ole@....pl>
> Tested-by: Krzysztof Oledzki <ole@....pl>
> Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>

Applied, thanks Eric.

You voiced some concerns about window clamp route and socket settings
and whatnot.  But I think the route side should be OK.  When a new
connect() occurs, TCP will reinitialize the window clamp setting based
upon the route metric and other values.

The TCP_WINDOW_CLAMP socket option case is tedious however.  If we
want to preserve such settings across disconnect operations we'll need
to store two pieces of state I believe.
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