From: Patrick McHardy <kaber@trash.net>
Subject: Re: [PATCH v3 10/10] nf_conntrack: Use rcu_barrier()
Date: Thu, 25 Jun 2009 16:33:44 +0200
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Cc: Christoph Lameter <cl@linux-foundation.org>, linux-mm@kvack.org,
	"David S. Miller" <davem@davemloft.net>,
	"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
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Jesper Dangaard Brouer wrote:
> RCU barriers, rcu_barrier(), is inserted two places.
> 
>  In nf_conntrack_expect.c nf_conntrack_expect_fini() before the
>  kmem_cache_destroy().  Firstly to make sure the callback to the
>  nf_ct_expect_free_rcu() code is still around.  Secondly because I'm
>  unsure about the consequence of having in flight
>  nf_ct_expect_free_rcu/kmem_cache_free() calls while doing a
>  kmem_cache_destroy() slab destroy.
> 
>  And in nf_conntrack_extend.c nf_ct_extend_unregister(), inorder to
>  wait for completion of callbacks to __nf_ct_ext_free_rcu(), which is
>  invoked by __nf_ct_ext_add().  It might be more efficient to call
>  rcu_barrier() in nf_conntrack_core.c nf_conntrack_cleanup_net(), but
>  thats make it more difficult to read the code (as the callback code
>  in located in nf_conntrack_extend.c).

Applied, thanks Jesper.