netdev - RE: [PATCH 36/38] netfilter: connlimit: use keyed locks

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Message-ID: <063D6719AE5E284EB5DD2968C1650D6D0F6DF508@AcuExch.aculab.com>
Date:	Mon, 17 Mar 2014 14:40:36 +0000
From:	David Laight <David.Laight@...LAB.COM>
To:	'Florian Westphal' <fw@...len.de>
CC:	'Pablo Neira Ayuso' <pablo@...filter.org>,
	"netfilter-devel@...r.kernel.org" <netfilter-devel@...r.kernel.org>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH 36/38] netfilter: connlimit: use keyed locks

From: Florian Westphal
> David Laight <David.Laight@...LAB.COM> wrote:
> > From: Pablo Neira Ayuso
> > > +#define CONNLIMIT_SLOTS	256
> > > +#define CONNLIMIT_LOCK_SLOTS	32
> >
> > You might want to make these explicitly unsigned to ensure
> > the divisions are unsigned (so can be done with a simple mask).
> 
> I can do  this but I checked that at least on my machine gcc already
> emits a 'add' instruction to reduce the hash value.

I think you meant 'and' :-)
Yes the hash itself is probably unsigned so forces an unsigned modulus.
It just seemed better to force it from the other argument as well.

	David



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