From: Patrick McHardy <kaber@trash.net>
To: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
netfilter-devel@vger.kernel.org,
Stephen Hemminger <shemminger@vyatta.com>
Subject: Re: [PATCH] netfilter: ctnetlink: fix (really) race condition between dump_table and destroy
Date: Mon, 24 Jan 2011 14:37:35 +0100 [thread overview]
Message-ID: <4D3D809F.30808@trash.net> (raw)
In-Reply-To: <4D3D7DD5.9020902@netfilter.org>
On 24.01.2011 14:25, Pablo Neira Ayuso wrote:
> On 24/01/11 14:12, Eric Dumazet wrote:
>> Le lundi 24 janvier 2011 à 14:06 +0100, Pablo Neira Ayuso a écrit :
>>
>>> Yes, we can use nf_conntrack_get (which does atomic_inc) instead. New
>>> patch attached.
>>
>> I feel now a bit uncomfortable, sorry ;)
>>
>> Are we sure the refcount cannot reach 0 while we hold
>> nf_conntrack_lock ?
>
> the ct deletion from the hash list is protected by spin lock, so
> whatever deletion would wait until we have left the dump section.
>
> with this patch, the code looks like it was in 2.6.24 before the rcu stuff.
Yeah, we definitely have a reference while the conntrack is contained
in the hash table, and removal requires taking nf_conntrack_lock,
therefor using the conntrack entry while holding the lock is valid.
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next prev parent reply other threads:[~2011-01-24 13:37 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-23 23:16 [PATCH] netfilter: ctnetlink: fix (really) race condition between dump_table and destroy Pablo Neira Ayuso
2011-01-24 6:41 ` Eric Dumazet
2011-01-24 7:04 ` Eric Dumazet
2011-01-24 11:57 ` Pablo Neira Ayuso
2011-01-24 12:46 ` Patrick McHardy
2011-01-24 12:54 ` Eric Dumazet
2011-01-24 13:06 ` Pablo Neira Ayuso
2011-01-24 13:12 ` Eric Dumazet
2011-01-24 13:25 ` Pablo Neira Ayuso
2011-01-24 13:37 ` Patrick McHardy [this message]
2011-01-24 14:06 ` Eric Dumazet
2011-01-24 17:53 ` Patrick McHardy
2011-01-24 18:01 ` Eric Dumazet
2011-01-24 18:16 ` Patrick McHardy
2011-02-20 20:48 ` Stephen Hemminger
2011-02-20 20:51 ` [PATCH 1/2] netfilter: fix race in conntrack " Stephen Hemminger
2011-02-20 20:51 ` [PATCH 2/2] netfilter: ctnetlink: fix missing refcount increment during dumps Stephen Hemminger
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