netdev - Re: [v2,2/2] tools: bpftool: add net detach command to detach XDP on interface

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Date:   Thu, 1 Aug 2019 23:25:26 -0700
From:   Y Song <ys114321@...il.com>
To:     "Daniel T. Lee" <danieltimlee@...il.com>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Alexei Starovoitov <ast@...nel.org>,
        netdev <netdev@...r.kernel.org>
Subject: Re: [v2,2/2] tools: bpftool: add net detach command to detach XDP on interface

On Thu, Aug 1, 2019 at 2:04 AM Daniel T. Lee <danieltimlee@...il.com> wrote:
>
> By this commit, using `bpftool net detach`, the attached XDP prog can
> be detached. Detaching the BPF prog will be done through libbpf
> 'bpf_set_link_xdp_fd' with the progfd set to -1.
>
> Signed-off-by: Daniel T. Lee <danieltimlee@...il.com>
> ---
> Changes in v2:
>   - command 'unload' changed to 'detach' for the consistency
>
>  tools/bpf/bpftool/net.c | 55 ++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 54 insertions(+), 1 deletion(-)
>
> diff --git a/tools/bpf/bpftool/net.c b/tools/bpf/bpftool/net.c
> index f3b57660b303..2ae9a613b05c 100644
> --- a/tools/bpf/bpftool/net.c
> +++ b/tools/bpf/bpftool/net.c
> @@ -281,6 +281,31 @@ static int parse_attach_args(int argc, char **argv, int *progfd,
>         return 0;
>  }
>
> +static int parse_detach_args(int argc, char **argv,
> +                            enum net_attach_type *attach_type, int *ifindex)
> +{
> +       if (!REQ_ARGS(2))
> +               return -EINVAL;
> +
> +       *attach_type = parse_attach_type(*argv);
> +       if (*attach_type == __MAX_NET_ATTACH_TYPE) {
> +               p_err("invalid net attach/detach type");
> +               return -EINVAL;
> +       }
> +
> +       NEXT_ARG();
> +       if (!REQ_ARGS(1))
> +               return -EINVAL;
> +
> +       *ifindex = if_nametoindex(*argv);
> +       if (!*ifindex) {
> +               p_err("Invalid ifname");
> +               return -EINVAL;
> +       }
> +
> +       return 0;
> +}
> +
>  static int do_attach_detach_xdp(int *progfd, enum net_attach_type *attach_type,
>                                 int *ifindex)
>  {
> @@ -323,6 +348,31 @@ static int do_attach(int argc, char **argv)
>         return 0;
>  }
>
> +static int do_detach(int argc, char **argv)
> +{
> +       enum net_attach_type attach_type;
> +       int err, progfd, ifindex;
> +
> +       err = parse_detach_args(argc, argv, &attach_type, &ifindex);
> +       if (err)
> +               return err;
> +
> +       /* to detach xdp prog */
> +       progfd = -1;
> +       if (is_prefix("xdp", attach_type_strings[attach_type]))
> +               err = do_attach_detach_xdp(&progfd, &attach_type, &ifindex);

Similar to previous patch, parameters no need to be pointer.

> +
> +       if (err < 0) {
> +               p_err("link set %s failed", attach_type_strings[attach_type]);
> +               return -1;

Maybe "return err"?

> +       }
> +
> +       if (json_output)
> +               jsonw_null(json_wtr);
> +
> +       return 0;
> +}
> +
>  static int do_show(int argc, char **argv)
>  {
>         struct bpf_attach_info attach_info = {};
> @@ -406,6 +456,7 @@ static int do_help(int argc, char **argv)
>         fprintf(stderr,
>                 "Usage: %s %s { show | list } [dev <devname>]\n"
>                 "       %s %s attach PROG LOAD_TYPE <devname>\n"
> +               "       %s %s detach LOAD_TYPE <devname>\n"
>                 "       %s %s help\n"
>                 "\n"
>                 "       " HELP_SPEC_PROGRAM "\n"
> @@ -415,7 +466,8 @@ static int do_help(int argc, char **argv)
>                 "      to dump program attachments. For program types\n"
>                 "      sk_{filter,skb,msg,reuseport} and lwt/seg6, please\n"
>                 "      consult iproute2.\n",
> -               bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2]);
> +               bin_name, argv[-2], bin_name, argv[-2], bin_name, argv[-2],
> +               bin_name, argv[-2]);
>
>         return 0;
>  }
> @@ -424,6 +476,7 @@ static const struct cmd cmds[] = {
>         { "show",       do_show },
>         { "list",       do_show },
>         { "attach",     do_attach },
> +       { "detach",     do_detach },
>         { "help",       do_help },
>         { 0 }
>  };
> --
> 2.20.1
>