[xdp-hints] Re: [PATCH bpf-next v2 5/8] selftests/bpf: Verify xdp_metadata xdp->af_xdp path

[Anton Protopopov <aspsk@isovalent.com>]

On 22/11/21 10:25, Stanislav Fomichev wrote:
>
> [...]
>
> +
> +	if (bpf_xdp_metadata_rx_timestamp_supported(ctx))
> +		meta->rx_timestamp = bpf_xdp_metadata_rx_timestamp(ctx);
> +
> +	if (bpf_xdp_metadata_rx_hash_supported(ctx))
> +		meta->rx_hash = bpf_xdp_metadata_rx_hash(ctx);

Is there a case when F_supported and F are not called in a sequence? If not,
then you can join them:

	bool (*ndo_xdp_rx_timestamp)(const struct xdp_md *ctx, u64 *timestamp);

so that a calling XDP program does one indirect call instead of two for one
field

	if (bpf_xdp_metadata_rx_timestamp(ctx, &meta->rx_timestamp)) {
		/* ... couldn't get the timestamp */
	}