Re: [PATCH] bpftool: add support of pin prog by name

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Sat, Dec 4, 2021 at 8:51 PM <menglong8.dong@gmail.com> wrote:
>
> From: Menglong Dong <imagedong@tencent.com>
>
> For now, the command 'bpftool prog loadall' use section name as the
> name of the pin file. However, once there are prog with the same
> section name in ELF file, this command will failed with the error
> 'File Exist'.
>
> So, add the support of pin prog by function name with the 'pinbyname'
> argument.
>
> Signed-off-by: Menglong Dong <imagedong@tencent.com>
> ---

Doesn't [0] do that already?

  [0] https://patchwork.kernel.org/project/netdevbpf/patch/20211021214814.1236114-2-sdf@google.com/

>  tools/bpf/bpftool/prog.c | 7 +++++++
>  tools/lib/bpf/libbpf.c   | 5 +++++
>  tools/lib/bpf/libbpf.h   | 2 ++
>  3 files changed, 14 insertions(+)
>
> diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
> index e47e8b06cc3d..74e0aaebfefc 100644
> --- a/tools/bpf/bpftool/prog.c
> +++ b/tools/bpf/bpftool/prog.c
> @@ -1471,6 +1471,7 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
>         unsigned int old_map_fds = 0;
>         const char *pinmaps = NULL;
>         struct bpf_object *obj;
> +       bool pinbyname = false;
>         struct bpf_map *map;
>         const char *pinfile;
>         unsigned int i, j;
> @@ -1589,6 +1590,9 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
>                                 goto err_free_reuse_maps;
>
>                         pinmaps = GET_ARG();
> +               } else if (is_prefix(*argv, "pinbyname")) {
> +                       pinbyname = true;
> +                       NEXT_ARG();
>                 } else {
>                         p_err("expected no more arguments, 'type', 'map' or 'dev', got: '%s'?",
>                               *argv);
> @@ -1616,6 +1620,9 @@ static int load_with_options(int argc, char **argv, bool first_prog_only)
>                                 goto err_close_obj;
>                 }
>
> +               if (pinbyname)
> +                       bpf_program__set_pinname(pos,
> +                                                (char *)bpf_program__name(pos));
>                 bpf_program__set_ifindex(pos, ifindex);
>                 bpf_program__set_type(pos, prog_type);
>                 bpf_program__set_expected_attach_type(pos, expected_attach_type);
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index f6faa33c80fa..e8fc1d0fe16e 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -8119,6 +8119,11 @@ void bpf_program__set_ifindex(struct bpf_program *prog, __u32 ifindex)
>         prog->prog_ifindex = ifindex;
>  }
>
> +void bpf_program__set_pinname(struct bpf_program *prog, char *name)
> +{
> +       prog->pin_name = name;

BPF maps have bpf_map__set_pin_path(), setting a full path is more
flexible approach, I think, so if we had to do something here, it's
better to add bpf_program__set_ping_path().


> +}
> +
>  const char *bpf_program__name(const struct bpf_program *prog)
>  {
>         return prog->name;
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index 4ec69f224342..107cf736c2bb 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -216,6 +216,8 @@ LIBBPF_API int bpf_program__set_priv(struct bpf_program *prog, void *priv,
>  LIBBPF_API void *bpf_program__priv(const struct bpf_program *prog);
>  LIBBPF_API void bpf_program__set_ifindex(struct bpf_program *prog,
>                                          __u32 ifindex);
> +LIBBPF_API void bpf_program__set_pinname(struct bpf_program *prog,
> +                                        char *name);
>
>  LIBBPF_API const char *bpf_program__name(const struct bpf_program *prog);
>  LIBBPF_API const char *bpf_program__section_name(const struct bpf_program *prog);
> --
> 2.30.2
>