Re: [PATCH bpf-next v4 7/9] libbpf: add bpf_map__inner_map API

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

On Wed, Apr 7, 2021 at 11:14 PM Yauheni Kaliuta
<yauheni.kaliuta@redhat.com> wrote:
>
> From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
>
> The API gives access to inner map for map in map types (array or
> hash of map). It will be used to dynamically set max_entries in it.
>
> Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
> ---
>  tools/lib/bpf/libbpf.c   | 10 ++++++++++
>  tools/lib/bpf/libbpf.h   |  1 +
>  tools/lib/bpf/libbpf.map |  1 +
>  3 files changed, 12 insertions(+)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 7aad78dbb4b4..ed5586cce227 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -2194,6 +2194,7 @@ static int parse_btf_map_def(struct bpf_object *obj,
>                         map->inner_map = calloc(1, sizeof(*map->inner_map));
>                         if (!map->inner_map)
>                                 return -ENOMEM;
> +                       map->inner_map->fd = -1;
>                         map->inner_map->sec_idx = obj->efile.btf_maps_shndx;
>                         map->inner_map->name = malloc(strlen(map->name) +
>                                                       sizeof(".inner") + 1);
> @@ -3845,6 +3846,14 @@ __u32 bpf_map__max_entries(const struct bpf_map *map)
>         return map->def.max_entries;
>  }
>
> +struct bpf_map *bpf_map__inner_map(struct bpf_map *map)
> +{
> +       if (!bpf_map_type__is_map_in_map(map->def.type))
> +               return NULL;
> +
> +       return map->inner_map;
> +}
> +
>  int bpf_map__set_max_entries(struct bpf_map *map, __u32 max_entries)
>  {
>         if (map->fd >= 0)
> @@ -9476,6 +9485,7 @@ int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd)
>                 pr_warn("error: inner_map_fd already specified\n");
>                 return -EINVAL;
>         }
> +       zfree(&map->inner_map);
>         map->inner_map_fd = fd;
>         return 0;
>  }
> diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h
> index f500621d28e5..bec4e6a6e31d 100644
> --- a/tools/lib/bpf/libbpf.h
> +++ b/tools/lib/bpf/libbpf.h
> @@ -480,6 +480,7 @@ LIBBPF_API int bpf_map__pin(struct bpf_map *map, const char *path);
>  LIBBPF_API int bpf_map__unpin(struct bpf_map *map, const char *path);
>
>  LIBBPF_API int bpf_map__set_inner_map_fd(struct bpf_map *map, int fd);
> +LIBBPF_API struct bpf_map *bpf_map__inner_map(struct bpf_map *map);
>
>  LIBBPF_API long libbpf_get_error(const void *ptr);
>
> diff --git a/tools/lib/bpf/libbpf.map b/tools/lib/bpf/libbpf.map
> index f5990f7208ce..9768daa75415 100644
> --- a/tools/lib/bpf/libbpf.map
> +++ b/tools/lib/bpf/libbpf.map
> @@ -349,6 +349,7 @@ LIBBPF_0.3.0 {
>                 ring_buffer__epoll_fd;
>                 xsk_setup_xdp_prog;
>                 xsk_socket__update_xskmap;
> +               bpf_map__inner_map;

This is neither in the right version (should be in 0.4.0) nor is in
alphabetical order (despite cover letter saying otherwise).
But I've fixed it up while applying. Please be more careful next time.

>  } LIBBPF_0.2.0;
>
>  LIBBPF_0.4.0 {

> --
> 2.31.1
>