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netfilter: use jump_label for nf_hooks

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On configs where CONFIG_JUMP_LABEL=y, we can replace in fast path a
load/compare/conditional jump by a single jump with no dcache reference.

Jump target is modified as soon as nf_hooks[pf][hook] switches from
empty state to non empty states. jump_label state is kept outside of
nf_hooks array so has no cost on cpu caches.

This patch removes the test on CONFIG_NETFILTER_DEBUG : No need to call
nf_hook_slow() at all if nf_hooks[pf][hook] is empty, this didnt give
useful information, but slowed down things a lot.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Patrick McHardy <kaber@trash.net>
CC: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2011-11-18 17:32:46 +00:00
committed by David S. Miller
parent 9205fd9cca
commit a2d7ec58ac
2 changed files with 33 additions and 6 deletions
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13
net/netfilter/core.c
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@@ -54,6 +54,12 @@ EXPORT_SYMBOL_GPL(nf_unregister_afinfo);
struct list_head nf_hooks[NFPROTO_NUMPROTO][NF_MAX_HOOKS] __read_mostly;
EXPORT_SYMBOL(nf_hooks);
#if defined(CONFIG_JUMP_LABEL)
struct jump_label_key nf_hooks_needed[NFPROTO_NUMPROTO][NF_MAX_HOOKS];
EXPORT_SYMBOL(nf_hooks_needed);
#endif
static DEFINE_MUTEX(nf_hook_mutex);
int nf_register_hook(struct nf_hook_ops *reg)
@@ -70,6 +76,9 @@ int nf_register_hook(struct nf_hook_ops *reg)
}
list_add_rcu(&reg->list, elem->list.prev);
mutex_unlock(&nf_hook_mutex);
#if defined(CONFIG_JUMP_LABEL)
jump_label_inc(&nf_hooks_needed[reg->pf][reg->hooknum]);
#endif
return 0;
}
EXPORT_SYMBOL(nf_register_hook);
@@ -79,7 +88,9 @@ void nf_unregister_hook(struct nf_hook_ops *reg)
mutex_lock(&nf_hook_mutex);
list_del_rcu(&reg->list);
mutex_unlock(&nf_hook_mutex);
#if defined(CONFIG_JUMP_LABEL)
jump_label_dec(&nf_hooks_needed[reg->pf][reg->hooknum]);
#endif
synchronize_net();
}
EXPORT_SYMBOL(nf_unregister_hook);