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

[Hengqi Chen <hengqi.chen@gmail.com>]

On 2021/10/20 1:48 AM, Andrii Nakryiko wrote:
> 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.
> 
> 

Got it. Will do.

>> 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:
> 

I am a little confused about this scheduling. You mentioned that
we can deprecate old API on the development version (0.6). See [0].


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

Will take this in v2.

>>  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,
> 
> [...]
> 

  [0] https://lore.kernel.org/all/CAEf4BzZ_JB1VLAF0=7gu=2M0M735aXava=nPL8m8ewQWdS3m8g@mail.gmail.com/