From: Patrick McHardy <kaber@trash.net>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Jesper Dangaard Brouer <hawk@diku.dk>,
paulmck@linux.vnet.ibm.com, Changli Gao <xiaosuo@gmail.com>,
hawk@comx.dk,
Linux Kernel Network Hackers <netdev@vger.kernel.org>,
Netfilter Developers <netfilter-devel@vger.kernel.org>
Subject: Re: DDoS attack causing bad effect on conntrack searches
Date: Fri, 23 Apr 2010 13:06:45 +0200 [thread overview]
Message-ID: <4BD17F45.3030802@trash.net> (raw)
In-Reply-To: <1272020717.7895.7974.camel@edumazet-laptop>
Eric Dumazet wrote:
> Le vendredi 23 avril 2010 à 12:55 +0200, Patrick McHardy a écrit :
>> Eric Dumazet wrote:
>>> OK but a lookup last a fraction of a micro second, unless interrupted by
>>> hard irq.
>>>
>>> Probability of a change during a lookup should be very very small.
>>>
>>> Note that the scenario for a restart is :
>>>
>>> The lookup go through the chain.
>>> While it is examining one object, this object is deleted.
>>> The object is re-allocated by another cpu and inserted to a new chain.
>> I think another scenario that seems a bit more likely would be
>> that a new entry is added to the chain after it was fully searched.
>> Perhaps we could continue searching at the last position if the
>> last entry is not a nulls entry to improve this.
>
> But the last entry is always a nulls entry, what do you mean exactly ?
>
> When an unsert (of a fresh object, not a reused one) is done, this
> doesnt affect lookups in any way, since its done at the head of list.
Right, I missed that :)
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next prev parent reply other threads:[~2010-04-23 11:06 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-22 12:58 DDoS attack causing bad effect on conntrack searches Jesper Dangaard Brouer
2010-04-22 13:13 ` Changli Gao
2010-04-22 13:17 ` Patrick McHardy
2010-04-22 14:36 ` Eric Dumazet
2010-04-22 14:53 ` Eric Dumazet
2010-04-22 15:51 ` Paul E. McKenney
2010-04-22 16:02 ` Eric Dumazet
2010-04-22 16:34 ` Paul E. McKenney
2010-04-22 20:38 ` Jesper Dangaard Brouer
2010-04-22 21:03 ` Eric Dumazet
2010-04-22 21:14 ` Eric Dumazet
2010-04-22 23:44 ` David Miller
2010-04-23 5:44 ` Eric Dumazet
2010-04-23 8:13 ` David Miller
2010-04-23 8:18 ` David Miller
2010-04-23 8:40 ` Jesper Dangaard Brouer
2010-04-23 10:36 ` Patrick McHardy
2010-04-23 11:06 ` Eric Dumazet
2010-04-22 21:28 ` Jesper Dangaard Brouer
2010-04-23 7:23 ` Jan Engelhardt
2010-04-23 7:46 ` Eric Dumazet
2010-04-23 7:55 ` Jan Engelhardt
2010-04-23 9:23 ` Eric Dumazet
2010-04-23 10:55 ` Patrick McHardy
2010-04-23 11:05 ` Eric Dumazet
2010-04-23 11:06 ` Patrick McHardy [this message]
2010-04-23 20:57 ` Eric Dumazet
2010-04-24 11:11 ` Jesper Dangaard Brouer
2010-04-24 20:11 ` Eric Dumazet
2010-04-26 14:36 ` Jesper Dangaard Brouer
2010-05-31 21:21 ` Eric Dumazet
2010-06-01 0:28 ` Changli Gao
2010-06-01 5:05 ` Eric Dumazet
2010-06-01 5:48 ` Changli Gao
2010-06-01 10:18 ` Patrick McHardy
2010-06-01 10:31 ` Eric Dumazet
2010-06-01 10:41 ` Patrick McHardy
2010-06-01 16:20 ` [RFC nf-next-2.6] conntrack: per cpu nf_conntrack_untracked Eric Dumazet
2010-06-04 11:40 ` Patrick McHardy
2010-06-04 12:10 ` Changli Gao
2010-06-04 12:29 ` Patrick McHardy
2010-06-04 12:36 ` Eric Dumazet
2010-06-04 16:25 ` [PATCH nf-next-2.6] conntrack: IPS_UNTRACKED bit Eric Dumazet
2010-06-04 20:15 ` [PATCH nf-next-2.6 2/2] conntrack: per_cpu untracking Eric Dumazet
2010-06-08 14:29 ` Patrick McHardy
2010-06-08 14:52 ` Eric Dumazet
2010-06-08 15:12 ` Eric Dumazet
2010-06-09 12:45 ` Patrick McHardy
2010-06-08 14:12 ` [PATCH nf-next-2.6] conntrack: IPS_UNTRACKED bit Patrick McHardy
2010-04-23 10:56 ` DDoS attack causing bad effect on conntrack searches Patrick McHardy
2010-04-23 12:45 ` Jesper Dangaard Brouer
2010-04-23 13:57 ` Patrick McHardy
2010-04-22 13:31 ` Jesper Dangaard Brouer
2010-04-23 10:35 ` Patrick McHardy
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