netdev - Re: [PATCH net-next 2/4] net: bridge: rearrange flood vs unicast receive paths

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Date:	Fri, 15 Jul 2016 10:35:16 -0700
From:	Cong Wang <xiyou.wangcong@...il.com>
To:	Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Cc:	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	roopa@...ulusnetworks.com,
	Stephen Hemminger <stephen@...workplumber.org>,
	David Miller <davem@...emloft.net>,
	bridge@...ts.linux-foundation.org
Subject: Re: [PATCH net-next 2/4] net: bridge: rearrange flood vs unicast
 receive paths

On Wed, Jul 13, 2016 at 8:10 PM, Nikolay Aleksandrov
<nikolay@...ulusnetworks.com> wrote:
> This patch removes one conditional from the unicast path by using the fact
> that skb is NULL only when the packet is multicast or is local.
>
> Signed-off-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
> ---
>  net/bridge/br_input.c | 29 ++++++++++++++---------------
>  1 file changed, 14 insertions(+), 15 deletions(-)
>
> diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
> index 0b6d32619468..c20c5be6fc22 100644
> --- a/net/bridge/br_input.c
> +++ b/net/bridge/br_input.c
> @@ -134,10 +134,10 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
>         struct net_bridge_port *p = br_port_get_rcu(skb->dev);
>         const unsigned char *dest = eth_hdr(skb)->h_dest;
>         struct net_bridge_fdb_entry *dst = NULL;
> +       bool mcast_hit = false, unicast = true;
>         struct net_bridge_mdb_entry *mdst;
>         struct net_bridge *br;
>         struct sk_buff *skb2;
> -       bool unicast = true;
>         u16 vid = 0;
>
>         if (!p || p->state == BR_STATE_DISABLED)
> @@ -177,30 +177,29 @@ int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb
>                 if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
>                     br_multicast_querier_exists(br, eth_hdr(skb))) {
>                         if ((mdst && mdst->mglist) ||
> -                           br_multicast_is_router(br))
> +                           br_multicast_is_router(br)) {
>                                 skb2 = skb;
> -                       br_multicast_forward(mdst, skb, skb2);
> -                       skb = NULL;
> -                       if (!skb2)
> -                               goto out;
> +                               br->dev->stats.multicast++;
> +                       }
> +                       mcast_hit = true;
>                 } else {
>                         skb2 = skb;
> +                       br->dev->stats.multicast++;
>                 }
>                 unicast = false;
> -               br->dev->stats.multicast++;


Looks like you change the unconditional increment of this counter,
is this intended?