[nf-next,RFC,03/10] netfilter: bridge: kill NF_HOOK_THRESH() and state->tresh

Patch c5136b15ea36 ("netfilter: bridge: add and use br_nf_hook_thresh")
introduced br_nf_hook_thresh().

Replace NF_HOOK_THRESH() by br_nf_hook_thresh from
br_nf_forward_finish(), so we have no more callers for this macro.

As a result, state->thresh and explicit thresh parameter in the hook
state structure is not required anymore.

And we can get rid of fast forward code in nf_iterate() in the core path
that is only used by br_netfilter to search for the filter hook.

Suggested-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
---
 include/linux/netfilter.h             | 50 +++++++++--------------------------
 include/linux/netfilter_ingress.h     |  2 +-
 net/bridge/br_netfilter_hooks.c       |  8 +++---
 net/bridge/netfilter/ebtable_broute.c |  2 +-
 net/netfilter/core.c                  |  4 ---
 net/netfilter/nf_queue.c              |  1 -
 6 files changed, 19 insertions(+), 48 deletions(-)

Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> Patch c5136b15ea36 ("netfilter: bridge: add and use br_nf_hook_thresh")
> introduced br_nf_hook_thresh().
> 
> Replace NF_HOOK_THRESH() by br_nf_hook_thresh from
> br_nf_forward_finish(), so we have no more callers for this macro.
> 
> As a result, state->thresh and explicit thresh parameter in the hook
> state structure is not required anymore.
> 
> And we can get rid of fast forward code in nf_iterate() in the core path
> that is only used by br_netfilter to search for the filter hook.

Note that you will need to move more parts of nf_hook_slow() into
br_nf_hook_thresh(); the bridge netfilter does need to thresh feature
that we have in nf_iterate().

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On Thu, Oct 13, 2016 at 02:25:45PM +0200, Florian Westphal wrote:
> Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > Patch c5136b15ea36 ("netfilter: bridge: add and use br_nf_hook_thresh")
> > introduced br_nf_hook_thresh().
> > 
> > Replace NF_HOOK_THRESH() by br_nf_hook_thresh from
> > br_nf_forward_finish(), so we have no more callers for this macro.
> > 
> > As a result, state->thresh and explicit thresh parameter in the hook
> > state structure is not required anymore.
> > 
> > And we can get rid of fast forward code in nf_iterate() in the core path
> > that is only used by br_netfilter to search for the filter hook.
> 
> Note that you will need to move more parts of nf_hook_slow() into
> br_nf_hook_thresh(); the bridge netfilter does need to thresh feature
> that we have in nf_iterate().

br_nf_hook_thresh() is already skipping hooks before NF_BR_PRI_BRNF to
emulate thresh. What else is missing?
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Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> On Thu, Oct 13, 2016 at 02:25:45PM +0200, Florian Westphal wrote:
> > Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > > Patch c5136b15ea36 ("netfilter: bridge: add and use br_nf_hook_thresh")
> > > introduced br_nf_hook_thresh().
> > > 
> > > Replace NF_HOOK_THRESH() by br_nf_hook_thresh from
> > > br_nf_forward_finish(), so we have no more callers for this macro.
> > > 
> > > As a result, state->thresh and explicit thresh parameter in the hook
> > > state structure is not required anymore.
> > > 
> > > And we can get rid of fast forward code in nf_iterate() in the core path
> > > that is only used by br_netfilter to search for the filter hook.
> > 
> > Note that you will need to move more parts of nf_hook_slow() into
> > br_nf_hook_thresh(); the bridge netfilter does need to thresh feature
> > that we have in nf_iterate().
> 
> br_nf_hook_thresh() is already skipping hooks before NF_BR_PRI_BRNF to
> emulate thresh. What else is missing?

AFAICS you are removing the NF_BR_PRI_BRNF skipping in this patch,
it relied on nf_hook_slow to do this (plus the state->thresh thing).
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On Thu, Oct 13, 2016 at 05:10:55PM +0200, Florian Westphal wrote:
> Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > On Thu, Oct 13, 2016 at 02:25:45PM +0200, Florian Westphal wrote:
> > > Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> > > > Patch c5136b15ea36 ("netfilter: bridge: add and use br_nf_hook_thresh")
> > > > introduced br_nf_hook_thresh().
> > > > 
> > > > Replace NF_HOOK_THRESH() by br_nf_hook_thresh from
> > > > br_nf_forward_finish(), so we have no more callers for this macro.
> > > > 
> > > > As a result, state->thresh and explicit thresh parameter in the hook
> > > > state structure is not required anymore.
> > > > 
> > > > And we can get rid of fast forward code in nf_iterate() in the core path
> > > > that is only used by br_netfilter to search for the filter hook.
> > > 
> > > Note that you will need to move more parts of nf_hook_slow() into
> > > br_nf_hook_thresh(); the bridge netfilter does need to thresh feature
> > > that we have in nf_iterate().
> > 
> > br_nf_hook_thresh() is already skipping hooks before NF_BR_PRI_BRNF to
> > emulate thresh. What else is missing?
> 
> AFAICS you are removing the NF_BR_PRI_BRNF skipping in this patch,
> it relied on nf_hook_slow to do this (plus the state->thresh thing).

int br_nf_hook_thresh(unsigned int hook, struct net *net,
                      struct sock *sk, struct sk_buff *skb,
                      struct net_device *indev,
                      struct net_device *outdev,
                      int (*okfn)(struct net *, struct sock *,
                                  struct sk_buff *))
{
        struct nf_hook_entry *elem;
        struct nf_hook_state state;
        int ret;

        elem = rcu_dereference(net->nf.hooks[NFPROTO_BRIDGE][hook]);

        while (elem && (elem->ops.priority <= NF_BR_PRI_BRNF))
                elem = rcu_dereference(elem->next);

        ...

        nf_hook_state_init(&state, elem, hook, NFPROTO_BRIDGE, indev, ...

Hm, but this code (before actually calling nf_hook_slow) is skipping
the hook until we get to NF_BR_PRI_BRNF + 1.

Then hook state sets hook_entry to elem.

Am I missing anything?
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Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> int br_nf_hook_thresh(unsigned int hook, struct net *net,
>                       struct sock *sk, struct sk_buff *skb,
>                       struct net_device *indev,
>                       struct net_device *outdev,
>                       int (*okfn)(struct net *, struct sock *,
>                                   struct sk_buff *))
> {
>         struct nf_hook_entry *elem;
>         struct nf_hook_state state;
>         int ret;
> 
>         elem = rcu_dereference(net->nf.hooks[NFPROTO_BRIDGE][hook]);
> 
>         while (elem && (elem->ops.priority <= NF_BR_PRI_BRNF))
>                 elem = rcu_dereference(elem->next);
> 
>         ...
> 
>         nf_hook_state_init(&state, elem, hook, NFPROTO_BRIDGE, indev, ...
> 
> Hm, but this code (before actually calling nf_hook_slow) is skipping
> the hook until we get to NF_BR_PRI_BRNF + 1.
> 
> Then hook state sets hook_entry to elem.
> 
> Am I missing anything?

Yes, I'm a moron -- Ignore.  I'll turn off the computer now.
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