Subject: Re: [PATCH 2/7] igb: take vlan double header into account

From: Maciej Fijalkowski <[email-masked]>
Date: Wed, 7 Oct 2020 23:06:15 +0200

On Wed, Oct 07, 2020 at 05:25:01PM +0200, [email-masked] wrote:
> From: Sven Auhagen <[email-masked]>
> 
> Increase the packet header padding to include double VLAN tagging.
> This patch uses a macro for this.
> 
> Signed-off-by: Sven Auhagen <[email-masked]>
> ---
>  drivers/net/ethernet/intel/igb/igb.h      | 5 +++++
>  drivers/net/ethernet/intel/igb/igb_main.c | 7 +++----
>  2 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/igb/igb.h b/drivers/net/ethernet/intel/igb/igb.h
> index 0286d2fceee4..7afb67cf9b94 100644
> --- a/drivers/net/ethernet/intel/igb/igb.h
> +++ b/drivers/net/ethernet/intel/igb/igb.h
> @@ -138,6 +138,8 @@ struct vf_mac_filter {
>  /* this is the size past which hardware will drop packets when setting LPE=0 */
>  #define MAXIMUM_ETHERNET_VLAN_SIZE 1522
>  
> +#define IGB_ETH_PKT_HDR_PAD	(ETH_HLEN + ETH_FCS_LEN + (VLAN_HLEN * 2))
> +
>  /* Supported Rx Buffer Sizes */
>  #define IGB_RXBUFFER_256	256
>  #define IGB_RXBUFFER_1536	1536
> @@ -247,6 +249,9 @@ enum igb_tx_flags {
>  #define IGB_SFF_ADDRESSING_MODE		0x4
>  #define IGB_SFF_8472_UNSUP		0x00
>  
> +/* TX ressources are shared between XDP and netstack
> + * and we need to tag the buffer type to distinguish them
> + */

s/ressources/resources/

This comment sort of does not belong to this commit but I'm not sure what
place would be better.

>  enum igb_tx_buf_type {
>  	IGB_TYPE_SKB = 0,
>  	IGB_TYPE_XDP,
> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
> index 08cc6f59aa2e..0a9198037b98 100644
> --- a/drivers/net/ethernet/intel/igb/igb_main.c
> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> @@ -2826,7 +2826,7 @@ static int igb_setup_tc(struct net_device *dev, enum tc_setup_type type,
>  
>  static int igb_xdp_setup(struct net_device *dev, struct bpf_prog *prog)
>  {
> -	int i, frame_size = dev->mtu + ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN;
> +	int i, frame_size = dev->mtu + IGB_ETH_PKT_HDR_PAD;
>  	struct igb_adapter *adapter = netdev_priv(dev);
>  	bool running = netif_running(dev);
>  	struct bpf_prog *old_prog;
> @@ -3950,8 +3950,7 @@ static int igb_sw_init(struct igb_adapter *adapter)
>  	/* set default work limits */
>  	adapter->tx_work_limit = IGB_DEFAULT_TX_WORK;
>  
> -	adapter->max_frame_size = netdev->mtu + ETH_HLEN + ETH_FCS_LEN +
> -				  VLAN_HLEN;
> +	adapter->max_frame_size = netdev->mtu + IGB_ETH_PKT_HDR_PAD;
>  	adapter->min_frame_size = ETH_ZLEN + ETH_FCS_LEN;
>  
>  	spin_lock_init(&adapter->nfc_lock);
> @@ -6491,7 +6490,7 @@ static void igb_get_stats64(struct net_device *netdev,
>  static int igb_change_mtu(struct net_device *netdev, int new_mtu)
>  {
>  	struct igb_adapter *adapter = netdev_priv(netdev);
> -	int max_frame = new_mtu + ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN;
> +	int max_frame = new_mtu + IGB_ETH_PKT_HDR_PAD;
>  
>  	if (adapter->xdp_prog) {
>  		int i;
> -- 
> 2.20.1
>