Patchwork netfilter 02/12: nf_conntrack: use hlist_add_head_rcu() in nf_conntrack_set_hashsize()

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Submitter Patrick McHardy
Date March 26, 2009, 7:02 p.m.
Message ID <20090326190227.23365.25636.sendpatchset@x2.localnet>
Download mbox | patch
Permalink /patch/25167/
State Accepted
Delegated to: David Miller
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Comments

Patrick McHardy - March 26, 2009, 7:02 p.m.
commit 78f3648601fdc7a8166748bbd6d0555a88efa24a
Author: Eric Dumazet <dada1@cosmosbay.com>
Date:   Wed Mar 25 17:24:34 2009 +0100

    netfilter: nf_conntrack: use hlist_add_head_rcu() in nf_conntrack_set_hashsize()
    
    Using hlist_add_head() in nf_conntrack_set_hashsize() is quite dangerous.
    Without any barrier, one CPU could see a loop while doing its lookup.
    Its true new table cannot be seen by another cpu, but previous table is still
    readable.
    
    Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
    Signed-off-by: Patrick McHardy <kaber@trash.net>

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Patch

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 55befe5..54e983f 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1121,7 +1121,7 @@  int nf_conntrack_set_hashsize(const char *val, struct kernel_param *kp)
 					struct nf_conntrack_tuple_hash, hnode);
 			hlist_del_rcu(&h->hnode);
 			bucket = __hash_conntrack(&h->tuple, hashsize, rnd);
-			hlist_add_head(&h->hnode, &hash[bucket]);
+			hlist_add_head_rcu(&h->hnode, &hash[bucket]);
 		}
 	}
 	old_size = nf_conntrack_htable_size;