On 1/28/19 11:16 AM, Maciej Fijalkowski wrote:
> From: Maciej Fijalkowski <[email protected]>
>
> Since we have a dedicated netlink attributes for xdp setup on a
> particular interface, it is now possible to retrieve the program id that
> is currently attached to the interface. The use case is targeted for
> sample xdp programs, which will store the program id just after loading
> bpf program onto iface. On shutdown, the sample will make sure that it
> can unload the program by querying again the iface and verifying that
> both program id's matches.
>
> Signed-off-by: Maciej Fijalkowski <[email protected]>
> Reviewed-by: Jakub Kicinski <[email protected]>
> ---
small nit.
> +
> +int bpf_get_link_xdp_id(int ifindex, __u32 *prog_id, __u32 flags)
> +{
> + struct xdp_id_md xdp_id = {};
> + int sock, ret;
> + __u32 nl_pid;
> + __u32 mask;
> +
> + if (flags & ~XDP_FLAGS_MASK)
> + return -EINVAL;
> +
> + /* Check whether the single {HW,DRV,SKB} mode is set */
> + flags &= XDP_FLAGS_MODES;
> + mask = flags - 1;
> + if (flags && flags & mask)
> + return -EINVAL;
> +
> + sock = libbpf_netlink_open(&nl_pid);
> + if (sock < 0)
> + return sock;
> +
> + xdp_id.ifindex = ifindex;
> + xdp_id.flags = flags;
> +
> + ret = libbpf_nl_get_link(sock, nl_pid, get_xdp_id, &xdp_id);
> + *prog_id = xdp_id.id;
just a nit but should we really set prog_id from user if there is
an error. Probably friendlier not to set caller data in error
case.
> +
> + close(sock);
> + return ret;
> +}
> +
> int libbpf_nl_get_link(int sock, unsigned int nl_pid,
> libbpf_dump_nlmsg_t dump_link_nlmsg, void *cookie)
> {
>
