netdev - Re: [PATCH net-next] bridge: Remove unnecessary vlan_put_tag in br_handle

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Date:	Wed, 22 Jan 2014 10:22:59 -0500
From:	Vlad Yasevich <vyasevic@...hat.com>
To:	Toshiaki Makita <makita.toshiaki@....ntt.co.jp>,
	"David S . Miller" <davem@...emloft.net>,
	Stephen Hemminger <stephen@...workplumber.org>,
	netdev@...r.kernel.org
Subject: Re: [PATCH net-next] bridge: Remove unnecessary vlan_put_tag in br_handle_vlan

On 01/21/2014 07:29 PM, Toshiaki Makita wrote:
> br_handle_vlan() pushes HW accelerated vlan tag into skbuff when outgoing
> port is the bridge device.
> This is unnecessary because __netif_receive_skb_core() can handle skbs
> with HW accelerated vlan tag. In current implementation,
> __netif_receive_skb_core() needs to extract the vlan tag embedded in skb
> data. This could cause low network performance especially when receiving
> frames at a high frame rate on the bridge device.
> 
> Signed-off-by: Toshiaki Makita <makita.toshiaki@....ntt.co.jp>

Acked-by: Vlad Yasevich <vyasevic@...hat.com>

-vlad

> ---
>  net/bridge/br_vlan.c | 21 ---------------------
>  1 file changed, 21 deletions(-)
> 
> diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
> index 7ffc801..4ca4d0a 100644
> --- a/net/bridge/br_vlan.c
> +++ b/net/bridge/br_vlan.c
> @@ -151,27 +151,6 @@ struct sk_buff *br_handle_vlan(struct net_bridge *br,
>  	br_vlan_get_tag(skb, &vid);
>  	if (test_bit(vid, pv->untagged_bitmap))
>  		skb = br_vlan_untag(skb);
> -	else {
> -		/* Egress policy says "send tagged".  If output device
> -		 * is the  bridge, we need to add the VLAN header
> -		 * ourselves since we'll be going through the RX path.
> -		 * Sending to ports puts the frame on the TX path and
> -		 * we let dev_hard_start_xmit() add the header.
> -		 */
> -		if (skb->protocol != htons(ETH_P_8021Q) &&
> -		    pv->port_idx == 0) {
> -			/* vlan_put_tag expects skb->data to point to
> -			 * mac header.
> -			 */
> -			skb_push(skb, ETH_HLEN);
> -			skb = __vlan_put_tag(skb, skb->vlan_proto, skb->vlan_tci);
> -			if (!skb)
> -				goto out;
> -			/* put skb->data back to where it was */
> -			skb_pull(skb, ETH_HLEN);
> -			skb->vlan_tci = 0;
> -		}
> -	}
>  
>  out:
>  	return skb;
> 

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