Re: [PATCH bpf-next 00/12] libbpf: Textual representation of enums

[Yonghong Song <yhs@fb.com>]

On 5/16/22 10:35 AM, Daniel Müller wrote:
> This patch set introduces the means for querying a textual representation of
> the following BPF related enum types:
> - enum bpf_map_type
> - enum bpf_prog_type
> - enum bpf_attach_type
> - enum bpf_link_type
> 
> To make that possible, we introduce a new public function for each of the types:
> libbpf_bpf_<type>_type_str.
> 
> Having a way to query a textual representation has been asked for in the past
> (by systemd, among others). Such representations can generally be useful in
> tracing and logging contexts, among others. At this point, at least one client,
> bpftool, maintains such a mapping manually, which is prone to get out of date as
> new enum variants are introduced. libbpf is arguably best situated to keep this
> list complete and up-to-date. This patch series adds BTF based tests to ensure
> that exhaustiveness is upheld moving forward.
> 
> The libbpf provided textual representation can be inferred from the
> corresponding enum variant name by removing the prefix and lowercasing the
> remainder. E.g., BPF_PROG_TYPE_SOCKET_FILTER -> socket_filter. Unfortunately,
> bpftool does not use such a programmatic approach for some of the
> bpf_attach_type variants. We propose a work around keeping the existing behavior
> for the time being in the patch titled "bpftool: Use
> libbpf_bpf_attach_type_str".
> 
> The patch series is structured as follows:
> - for each enumeration type in {bpf_prog_type, bpf_map_type, bpf_attach_type,
>    bpf_link_type}:
>    - we first introduce the corresponding public libbpf API function
>    - we then add BTF based self-tests
>    - we lastly adjust bpftool to use the libbpf provided functionality
> 
> Signed-off-by: Daniel Müller <deso@posteo.net>
> 
> Daniel Müller (12):
>    libbpf: Introduce libbpf_bpf_prog_type_str
>    selftests/bpf: Add test for libbpf_bpf_prog_type_str
>    bpftool: Use libbpf_bpf_prog_type_str
>    libbpf: Introduce libbpf_bpf_map_type_str
>    selftests/bpf: Add test for libbpf_bpf_map_type_str
>    bpftool: Use libbpf_bpf_map_type_str
>    libbpf: Introduce libbpf_bpf_attach_type_str
>    selftests/bpf: Add test for libbpf_bpf_attach_type_str
>    bpftool: Use libbpf_bpf_attach_type_str
>    libbpf: Introduce libbpf_bpf_link_type_str
>    selftests/bpf: Add test for libbpf_bpf_link_type_str
>    bpftool: Use libbpf_bpf_link_type_str
> 
>   tools/bpf/bpftool/cgroup.c                    |  20 +-
>   tools/bpf/bpftool/common.c                    |  46 ----
>   tools/bpf/bpftool/feature.c                   |  87 +++++---
>   tools/bpf/bpftool/link.c                      |  61 +++---
>   tools/bpf/bpftool/main.h                      |   6 -
>   tools/bpf/bpftool/map.c                       |  82 +++----
>   tools/bpf/bpftool/prog.c                      |  51 +----
>   tools/lib/bpf/libbpf.c                        | 160 ++++++++++++++
>   tools/lib/bpf/libbpf.h                        |  36 ++++
>   tools/lib/bpf/libbpf.map                      |   4 +
>   .../selftests/bpf/prog_tests/libbpf_str.c     | 201 ++++++++++++++++++
>   11 files changed, 539 insertions(+), 215 deletions(-)
>   create mode 100644 tools/testing/selftests/bpf/prog_tests/libbpf_str.c

LGTM. Ack for the whole series.
Acked-by: Yonghong Song <yhs@fb.com>