Re: [PATCH net-next 08/10] bpf: nfp: Report bpf_prog ID during XDP_QUERY_PROG

[Jakub Kicinski]

On Mon, 12 Jun 2017 18:00:23 -0700, Martin KaFai Lau wrote:
> +     case XDP_QUERY_PROG: {
> +             const struct bpf_prog *xdp_prog;
> +
> +             xdp_prog = READ_ONCE(nn->dp.xdp_prog);
> +             if (xdp_prog)
> +                     xdp->prog_id = xdp_prog->aux->id;
> +             else
> +                     xdp->prog_id = 0;
>               return 0;
> +     }
>       default:
>               return -EINVAL;
>       }

Why READ_ONCE?  I thought .ndo_xdp is always called under RTNL.