Subject: Re: [PATCH bpf-next v2 17/20] veth: Implement VLAN tag and checksum level XDP hint

From: Stanislav Fomichev <[email-masked]>
Date: Wed, 5 Jul 2023 10:25:01 -0700

On 07/03, Larysa Zaremba wrote:
> In order to test VLAN tag and checksum level XDP hints in
> hardware-independent selfttests, implement newly added XDP hints in veth
> driver.
> 
> Signed-off-by: Larysa Zaremba <[email-masked]>
> ---
>  drivers/net/veth.c | 40 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 40 insertions(+)
> 
> diff --git a/drivers/net/veth.c b/drivers/net/veth.c
> index 614f3e3efab0..a7f2b679551d 100644
> --- a/drivers/net/veth.c
> +++ b/drivers/net/veth.c
> @@ -1732,6 +1732,44 @@ static int veth_xdp_rx_hash(const struct xdp_md *ctx, u32 *hash,
>  	return 0;
>  }
>  
> +static int veth_xdp_rx_vlan_tag(const struct xdp_md *ctx, u16 *vlan_tag,
> +				__be16 *vlan_proto)
> +{
> +	struct veth_xdp_buff *_ctx = (void *)ctx;
> +	struct sk_buff *skb = _ctx->skb;
> +	int err;
> +
> +	if (!skb)
> +		return -ENODATA;
> +

[..]

> +	err = __vlan_hwaccel_get_tag(skb, vlan_tag);

We probably need to open code __vlan_hwaccel_get_tag here. Because it
returns -EINVAL on !skb_vlan_tag_present where the expectation, for us,
I'm assuming is -ENODATA?

> +	if (err)
> +		return err;
> +
> +	*vlan_proto = skb->vlan_proto;
> +	return err;
> +}
> +
> +static int veth_xdp_rx_csum_lvl(const struct xdp_md *ctx, u8 *csum_level)
> +{
> +	struct veth_xdp_buff *_ctx = (void *)ctx;
> +	struct sk_buff *skb = _ctx->skb;
> +
> +	if (!skb)
> +		return -ENODATA;
> +
> +	if (skb->ip_summed == CHECKSUM_UNNECESSARY)
> +		*csum_level = skb->csum_level;
> +	else if (skb->ip_summed == CHECKSUM_PARTIAL &&
> +		 skb_checksum_start_offset(skb) == skb_transport_offset(skb) ||
> +		 skb->csum_valid)
> +		*csum_level = 0;
> +	else
> +		return -ENODATA;
> +
> +	return 0;
> +}
> +
>  static const struct net_device_ops veth_netdev_ops = {
>  	.ndo_init            = veth_dev_init,
>  	.ndo_open            = veth_open,
> @@ -1756,6 +1794,8 @@ static const struct net_device_ops veth_netdev_ops = {
>  static const struct xdp_metadata_ops veth_xdp_metadata_ops = {
>  	.xmo_rx_timestamp		= veth_xdp_rx_timestamp,
>  	.xmo_rx_hash			= veth_xdp_rx_hash,
> +	.xmo_rx_vlan_tag		= veth_xdp_rx_vlan_tag,
> +	.xmo_rx_csum_lvl		= veth_xdp_rx_csum_lvl,
>  };
>  
>  #define VETH_FEATURES (NETIF_F_SG | NETIF_F_FRAGLIST | NETIF_F_HW_CSUM | \
> -- 
> 2.41.0
>