From 1d45209d89e647e9f27e4afa1f47338df73bc112 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Tue, 24 Mar 2009 14:26:50 +0100 Subject: [PATCH] netfilter: nf_conntrack: Reduce conntrack count in nf_conntrack_free() We use RCU to defer freeing of conntrack structures. In DOS situation, RCU might accumulate about 10.000 elements per CPU in its internal queues. To get accurate conntrack counts (at the expense of slightly more RAM used), we might consider conntrack counter not taking into account "about to be freed elements, waiting in RCU queues". We thus decrement it in nf_conntrack_free(), not in the RCU callback. Signed-off-by: Eric Dumazet Tested-by: Joakim Tjernlund Signed-off-by: Patrick McHardy --- net/netfilter/nf_conntrack_core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index ebc27560012..55befe59e1c 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -517,16 +517,17 @@ EXPORT_SYMBOL_GPL(nf_conntrack_alloc); static void nf_conntrack_free_rcu(struct rcu_head *head) { struct nf_conn *ct = container_of(head, struct nf_conn, rcu); - struct net *net = nf_ct_net(ct); nf_ct_ext_free(ct); kmem_cache_free(nf_conntrack_cachep, ct); - atomic_dec(&net->ct.count); } void nf_conntrack_free(struct nf_conn *ct) { + struct net *net = nf_ct_net(ct); + nf_ct_ext_destroy(ct); + atomic_dec(&net->ct.count); call_rcu(&ct->rcu, nf_conntrack_free_rcu); } EXPORT_SYMBOL_GPL(nf_conntrack_free); -- 2.41.1