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: <AANLkTinic7H0r7kAgsBiRAbn7MCeqxA0Gme7oOkmPUdJ@mail.gmail.com>
Date:	Fri, 20 Aug 2010 23:36:44 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	Eric Dumazet <eric.dumazet@...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

On Fri, Aug 20, 2010 at 11:29 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> 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.
>

Yes, and it isn't critical. I think this fix should be in a separate patch.


-- 
Regards,
Changli Gao(xiaosuo@...il.com)
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