netfilter: convert hook list to an array

This converts the storage and layout of netfilter hook entries from a
linked list to an array.  After this commit, hook entries will be
stored adjacent in memory.  The next pointer is no longer required.

The ops pointers are stored at the end of the array as they are only
used in the register/unregister path and in the legacy br_netfilter code.

nf_unregister_net_hooks() is slower than needed as it just calls
nf_unregister_net_hook in a loop (i.e. at least n synchronize_net()
calls), this will be addressed in followup patch.

Test setup:
 - ixgbe 10gbit
 - netperf UDP_STREAM, 64 byte packets
 - 5 hooks: (raw + mangle prerouting, mangle+filter input, inet filter):
empty mangle and raw prerouting, mangle and filter input hooks:
353.9
this patch:
364.2

Signed-off-by: Aaron Conole <aconole@bytheb.org>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 11 insertions, 8 deletions

diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 626f4b2..c2eea1b 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -985,22 +985,25 @@ int br_nf_hook_thresh(unsigned int hook, struct net *net,
 		      int (*okfn)(struct net *, struct sock *,
 				  struct sk_buff *))
 {
-	struct nf_hook_entry *elem;
+	const struct nf_hook_entries *e;
 	struct nf_hook_state state;
+	struct nf_hook_ops **ops;
+	unsigned int i;
 	int ret;
 
-	for (elem = rcu_dereference(net->nf.hooks[NFPROTO_BRIDGE][hook]);
-	     elem && nf_hook_entry_priority(elem) <= NF_BR_PRI_BRNF;
-	     elem = rcu_dereference(elem->next))
-		;
-
-	if (!elem)
+	e = rcu_dereference(net->nf.hooks[NFPROTO_BRIDGE][hook]);
+	if (!e)
 		return okfn(net, sk, skb);
 
+	ops = nf_hook_entries_get_hook_ops(e);
+	for (i = 0; i < e->num_hook_entries &&
+	      ops[i]->priority <= NF_BR_PRI_BRNF; i++)
+		;
+
 	nf_hook_state_init(&state, hook, NFPROTO_BRIDGE, indev, outdev,
 			   sk, net, okfn);
 
-	ret = nf_hook_slow(skb, &state, elem);
+	ret = nf_hook_slow(skb, &state, e, i);
 	if (ret == 1)
 		ret = okfn(net, sk, skb);