From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <dada1@cosmosbay.com>
Subject: Re: [PATCH] netfilter: use per-cpu spinlock rather than RCU (v3)
Date: Wed, 15 Apr 2009 23:07:29 +0200
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Cc: Patrick McHardy <kaber@trash.net>,
	Jeff Chua <jeff.chua.linux@gmail.com>,
	paulmck@linux.vnet.ibm.com, David Miller <davem@davemloft.net>,
	paulus@samba.org, mingo@elte.hu, torvalds@linux-foundation.org,
	laijs@cn.fujitsu.com, jengelh@medozas.de, r000n@r000n.net,
	linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org,
	netdev@vger.kernel.org, benh@kernel.crashing.org
To: Stephen Hemminger <shemminger@vyatta.com>
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Stephen Hemminger a =E9crit :
> Looks like there is some recursive path into ip_tables that makes the
> per-cpu spinlock break.  I get lockup's with KVM networking.
>=20
> Suggestions?

Well, it seems original patch was not so bad after all

http://lists.netfilter.org/pipermail/netfilter-devel/2006-January/02317=
5.html

So change per-cpu spinlocks to per-cpu rwlocks=20

and use read_lock() in ipt_do_table() to allow recursion...