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nf_conntrack: Use rcu_barrier()

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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).

Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
Signed-off-by: Patrick McHardy <kaber@trash.net>
This commit is contained in:
Jesper Dangaard Brouer 2009-06-25 16:32:52 +02:00 committed by Patrick McHardy
parent 28d0325ce6
commit 308ff823eb
2 changed files with 4 additions and 2 deletions
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4
net/netfilter/nf_conntrack_expect.c
View file

@ -617,8 +617,10 @@ err1:
void nf_conntrack_expect_fini(struct net *net)
{
exp_proc_remove(net);
if (net_eq(net, &init_net))
if (net_eq(net, &init_net)) {
rcu_barrier(); /* Wait for call_rcu() before destroy */
kmem_cache_destroy(nf_ct_expect_cachep);
}
nf_ct_free_hashtable(net->ct.expect_hash, net->ct.expect_vmalloc,
nf_ct_expect_hsize);
}

2
net/netfilter/nf_conntrack_extend.c
View file

@ -186,6 +186,6 @@ void nf_ct_extend_unregister(struct nf_ct_ext_type *type)
rcu_assign_pointer(nf_ct_ext_types[type->id], NULL);
update_alloc_size(type);
mutex_unlock(&nf_ct_ext_type_mutex);
synchronize_rcu();
rcu_barrier(); /* Wait for completion of call_rcu()'s */
}
EXPORT_SYMBOL_GPL(nf_ct_extend_unregister);