linux-kernel - Re: [PATCH v3] netfilter: save the hash of the tuple in the original direction for latter use

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Message-ID: <1282318163.2484.212.camel@edumazet-laptop>
Date:	Fri, 20 Aug 2010 17:29:23 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Changli Gao <xiaosuo@...il.com>
Cc:	Patrick McHardy <kaber@...sh.net>,
	"David S. Miller" <davem@...emloft.net>,
	Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
	akpm@...ux-foundation.org, netfilter-devel@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] netfilter: save the hash of the tuple in the
 original direction for latter use

Le vendredi 20 août 2010 à 23:22 +0800, Changli Gao a écrit :

> I should keep the old way, but fix a race.
> 
>         if (unlikely(!nf_conntrack_hash_rnd_initted)) {
>                 get_random_bytes(&nf_conntrack_hash_rnd,
>                                 sizeof(nf_conntrack_hash_rnd));
>                 nf_conntrack_hash_rnd_initted = 1;
>         }
> 
> nf_conntrack_alloc() isn't called with in the nf_conntrack_lock. So
> the above code maybe executed more than once on different CPUs. It is
> easy to fix with the cmpxchg() trick.

Sure, please fix the race first.

But as I said, its not critical, if one or two conntracks are hashed on
wrong basis. They will eventually disappear after timeout.



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