Re: [PATCH bpf-next 1/2] libbpf: Add btf__type_cnt() and btf__raw_data() APIs

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

On Sat, Oct 9, 2021 at 8:01 AM Hengqi Chen <hengqi.chen@gmail.com> wrote:
>
> Add btf__type_cnt() and btf__raw_data() APIs and deprecate
> btf__get_nr_type() and btf__get_raw_data() since the old APIs
> don't follow the libbpf naming convention for getters which
> omit 'get' in the name.[0] btf__raw_data() is just an alias to

nit: this ".[0]" looks out of place, please use it as a reference in a
sentence, e.g.,:

omit 'get' in the name (see [0]).

So that it reads naturally and fits the overall commit message.


> the existing btf__get_raw_data(). btf__type_cnt() now returns
> the number of all types of the BTF object including 'void'.
>
>   [0] Closes: https://github.com/libbpf/libbpf/issues/279
>
> Signed-off-by: Hengqi Chen <hengqi.chen@gmail.com>
> ---
>  tools/lib/bpf/btf.c      | 36 ++++++++++++++++++++++--------------
>  tools/lib/bpf/btf.h      |  4 ++++
>  tools/lib/bpf/btf_dump.c |  8 ++++----
>  tools/lib/bpf/libbpf.c   | 32 ++++++++++++++++----------------
>  tools/lib/bpf/libbpf.map |  2 ++
>  tools/lib/bpf/linker.c   | 28 ++++++++++++++--------------
>  6 files changed, 62 insertions(+), 48 deletions(-)
>

[...]

> diff --git a/tools/lib/bpf/btf.h b/tools/lib/bpf/btf.h
> index 864eb51753a1..49397a22d72b 100644
> --- a/tools/lib/bpf/btf.h
> +++ b/tools/lib/bpf/btf.h
> @@ -131,7 +131,9 @@ LIBBPF_API __s32 btf__find_by_name(const struct btf *btf,
>                                    const char *type_name);
>  LIBBPF_API __s32 btf__find_by_name_kind(const struct btf *btf,
>                                         const char *type_name, __u32 kind);
> +LIBBPF_DEPRECATED_SINCE(0, 6, "use btf__type_cnt() instead")

it has to be scheduled to 0.7 to have a release with new API
(btf__type_cnt) before we deprecate btf__get_nr_types(). It's probably
worth mentioning in the deprecation message that btf__type_cnt()
return is +1 from btf__get_nr_types(). Maybe something like:

LIBBPF_DEPRECATED_SINCE(0, 7, "use btf__type_cnt() instead; note that
btf__get_nr_types() == btf__type_cnt() - 1")

>  LIBBPF_API __u32 btf__get_nr_types(const struct btf *btf);
> +LIBBPF_API __u32 btf__type_cnt(const struct btf *btf);
>  LIBBPF_API const struct btf *btf__base_btf(const struct btf *btf);
>  LIBBPF_API const struct btf_type *btf__type_by_id(const struct btf *btf,
>                                                   __u32 id);
> @@ -144,7 +146,9 @@ LIBBPF_API int btf__resolve_type(const struct btf *btf, __u32 type_id);
>  LIBBPF_API int btf__align_of(const struct btf *btf, __u32 id);
>  LIBBPF_API int btf__fd(const struct btf *btf);
>  LIBBPF_API void btf__set_fd(struct btf *btf, int fd);
> +LIBBPF_DEPRECATED_SINCE(0, 6, "use btf__raw_data() instead")

same, 0.7+

>  LIBBPF_API const void *btf__get_raw_data(const struct btf *btf, __u32 *size);
> +LIBBPF_API const void *btf__raw_data(const struct btf *btf, __u32 *size);
>  LIBBPF_API const char *btf__name_by_offset(const struct btf *btf, __u32 offset);
>  LIBBPF_API const char *btf__str_by_offset(const struct btf *btf, __u32 offset);
>  LIBBPF_API int btf__get_map_kv_tids(const struct btf *btf, const char *map_name,

[...]