Subject: Re: [PATCH RESEND bpf-next 10/15] ice: Implement VLAN tag hint

From: Stanislav Fomichev <[email-masked]>
Date: Fri, 12 May 2023 11:31:21 -0700

On 05/12, Larysa Zaremba wrote:
> Implement .xmo_rx_vlan_tag callback to allow XDP code to read
> packet's VLAN tag.
> 
> Signed-off-by: Larysa Zaremba <[email-masked]>
> ---
>  drivers/net/ethernet/intel/ice/ice_txrx_lib.c | 44 +++++++++++++++++++
>  1 file changed, 44 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_txrx_lib.c b/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> index 1caa73644e7b..39547feb6106 100644
> --- a/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> +++ b/drivers/net/ethernet/intel/ice/ice_txrx_lib.c
> @@ -627,7 +627,51 @@ static int ice_xdp_rx_hash(const struct xdp_md *ctx, u32 *hash,
>  	return 0;
>  }
>  
> +/**
> + * ice_xdp_rx_ctag - VLAN tag XDP hint handler
> + * @ctx: XDP buff pointer
> + * @vlan_tag: destination address
> + *
> + * Copy VLAN tag (if was stripped) to the destination address.
> + */
> +static int ice_xdp_rx_ctag(const struct xdp_md *ctx, u16 *vlan_tag)
> +{
> +	const struct ice_xdp_buff *xdp_ext = (void *)ctx;
> +	netdev_features_t features;
> +

[..]

> +	features = xdp_ext->rx_ring->netdev->features;
> +
> +	if (!(features & NETIF_F_HW_VLAN_CTAG_RX))
> +		return -EINVAL;

Passing-by comment: why do we need to check features?
ice_get_vlan_tag_from_rx_desc seems to be checking a bunch of
fields in the descriptors, so that should be enough?

> +
> +	*vlan_tag = ice_get_vlan_tag_from_rx_desc(xdp_ext->eop_desc);

Should we also do the following:

if (!*vlan_tag)
	return -ENODATA;

?

> +	return 0;
> +}
> +
> +/**
> + * ice_xdp_rx_stag - VLAN s-tag XDP hint handler
> + * @ctx: XDP buff pointer
> + * @vlan_tag: destination address
> + *
> + * Copy VLAN s-tag (if was stripped) to the destination address.
> + */
> +static int ice_xdp_rx_stag(const struct xdp_md *ctx, u16 *vlan_tag)
> +{
> +	const struct ice_xdp_buff *xdp_ext = (void *)ctx;
> +	netdev_features_t features;
> +
> +	features = xdp_ext->rx_ring->netdev->features;
> +
> +	if (!(features & NETIF_F_HW_VLAN_STAG_RX))
> +		return -EINVAL;
> +
> +	*vlan_tag = ice_get_vlan_tag_from_rx_desc(xdp_ext->eop_desc);
> +	return 0;
> +}
> +
>  const struct xdp_metadata_ops ice_xdp_md_ops = {
>  	.xmo_rx_timestamp		= ice_xdp_rx_hw_ts,
>  	.xmo_rx_hash			= ice_xdp_rx_hash,
> +	.xmo_rx_ctag			= ice_xdp_rx_ctag,
> +	.xmo_rx_stag			= ice_xdp_rx_stag,
>  };
> -- 
> 2.35.3
>