netdev - Re: [PATCH] netfilter: don't scale the size of the window up twice

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Date:	Wed, 4 Apr 2012 21:05:26 +0200 (CEST)
From:	Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>
To:	Pablo Neira Ayuso <pablo@...filter.org>
cc:	Patrick McHardy <kaber@...sh.net>,
	"David S. Miller" <davem@...emloft.net>,
	netfilter-devel@...r.kernel.org, netdev@...r.kernel.org,
	Changli Gao <xiaosuo@...il.com>
Subject: Re: [PATCH] netfilter: don't scale the size of the window up twice

On Wed, 4 Apr 2012, Pablo Neira Ayuso wrote:

> On Mon, Apr 02, 2012 at 11:25:06AM +0800, Changli Gao wrote:
> > For a picked up connection, the window win is scaled twice: one is by the
> > initialization code, and the other is by the sender updating code.
> > 
> > I use the temporary variable swin instead of modifying the variable win.
> > 
> > Signed-off-by: Changli Gao <xiaosuo@...il.com>
> > ---
> >  net/netfilter/nf_conntrack_proto_tcp.c |    4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
> > index 361eade..0d07a1d 100644
> > --- a/net/netfilter/nf_conntrack_proto_tcp.c
> > +++ b/net/netfilter/nf_conntrack_proto_tcp.c
> > @@ -584,8 +584,8 @@ static bool tcp_in_window(const struct nf_conn *ct,
> >  			 * Let's try to use the data from the packet.
> >  			 */
> >  			sender->td_end = end;
> > -			win <<= sender->td_scale;
> > -			sender->td_maxwin = (win == 0 ? 1 : win);
> > +			swin = win << sender->td_scale;
> > +			sender->td_maxwin = (swin == 0 ? 1 : swin);
> >  			sender->td_maxend = end + sender->td_maxwin;
> >  			/*
> >  			 * We haven't seen traffic in the other direction yet
> 
> Jozsef, do you remember if this is intentional?

No, it's a good spotting.

Acked-by: Jozsef Kadlecsik <kadlec@...ckhole.kfki.hu>

> I'm going to test this patch in my testbed to make sure this does not
> break conntrackd.

A checking in a testbed doesn't hurt :-).

Best regards,
Jozsef
-
E-mail  : kadlec@...ckhole.kfki.hu, kadlecsik.jozsef@...ner.mta.hu
PGP key : http://www.kfki.hu/~kadlec/pgp_public_key.txt
Address : Wigner Research Centre for Physics, Hungarian Academy of Sciences
          H-1525 Budapest 114, POB. 49, Hungary
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