Subject: Re: [PATCH V1 5/6] net/mlx4_en: sk_prio <=> UP for untagged traffic

From: John Fastabend <[email-masked]>
Date: Wed, 21 Mar 2012 07:20:29 -0700

On 3/21/2012 2:25 AM, Amir Vadai wrote:
> From: Amir Vadai <[email-masked]>
> 
> Since vlan egress map is only good for tagged traffic, need to have other
> mapping to be used by untagged traffic.
> For that, the driver uses sch_mqprio mapping. This mapping could be set by
> using tc tool from iproute2 package.
> Mapped UP will be used by the HW for QoS purposes, but won't go out on the
> wire.
> 
> Signed-off-by: Amir Vadai <[email-masked]>
> ---

[...]

> diff --git a/drivers/net/ethernet/mellanox/mlx4/en_tx.c b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
> index 445a771..f228728 100644
> --- a/drivers/net/ethernet/mellanox/mlx4/en_tx.c
> +++ b/drivers/net/ethernet/mellanox/mlx4/en_tx.c
> @@ -570,15 +570,15 @@ static void build_inline_wqe(struct mlx4_en_tx_desc *tx_desc, struct sk_buff *sk
>  
>  u16 mlx4_en_select_queue(struct net_device *dev, struct sk_buff *skb)
>  {
> -	u16 vlan_tag = 0;
> +	int up = -1;
>  
> -	/* If we support per priority flow control and the packet contains
> -	 * a vlan tag, send the packet to the TX ring assigned to that priority
> -	 */
> -	if (vlan_tx_tag_present(skb)) {
> -		vlan_tag = vlan_tx_tag_get(skb);
> -		return MLX4_EN_NUM_TX_RINGS + (vlan_tag >> 13);
> -	}
> +	if (vlan_tx_tag_present(skb))
> +		up = (vlan_tx_tag_get(skb) >> 13);
> +	else if (dev->num_tc)
> +		up = netdev_get_prio_tc_map(dev, skb->priority);
> +
> +	if (up >= 0)
> +		return MLX4_EN_NUM_TX_RINGS + up;

I expected the else case covered by the netdev_set_tc_queue() setup above? Did
I miss something.

>  
>  	return __skb_tx_hash(dev, skb, MLX4_EN_NUM_TX_RINGS);
>  }