Re: [PATCH bpf-next 0/2] libbpf: Support uniform BTF-defined key/value specification across all BPF maps

On Thu, Sep 30, 2021 at 9:15 AM Hengqi Chen [off-list ref] wrote:

Currently a bunch of (usually pretty specialized) BPF maps do not support
specifying BTF types for they key and value. For such maps, specifying
their definition like this:

  struct {
      __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY);
      __type(key, int);
      __type(value, int);
  } my_perf_buf SEC(".maps");

Would actually produce warnings about retrying BPF map creation without BTF.
Users are forced to know such nuances and use __uint(key_size, 4) instead.
This is non-uniform, annoying, and inconvenient.

This patch set teaches libbpf to recognize those specialized maps and removes
BTF type IDs when creating BPF map. Also, update existing BPF selftests to
exericse this change.

Hengqi Chen (2):
  libbpf: Support uniform BTF-defined key/value specification across all
    BPF maps
  selftests/bpf: Use BTF-defined key/value for map definitions

 tools/lib/bpf/libbpf.c                        | 24 +++++++++++++++++++
 tools/testing/selftests/bpf/progs/kfree_skb.c |  4 ++--
 .../selftests/bpf/progs/perf_event_stackmap.c |  4 ++--
 .../bpf/progs/sockmap_verdict_prog.c          | 12 +++++-----
 .../selftests/bpf/progs/test_btf_map_in_map.c | 14 +++++------
 .../selftests/bpf/progs/test_map_in_map.c     | 10 ++++----
 .../bpf/progs/test_map_in_map_invalid.c       |  2 +-
 .../bpf/progs/test_pe_preserve_elems.c        |  8 +++----
 .../selftests/bpf/progs/test_perf_buffer.c    |  4 ++--
 .../bpf/progs/test_select_reuseport_kern.c    |  4 ++--
 .../bpf/progs/test_stacktrace_build_id.c      |  4 ++--
 .../selftests/bpf/progs/test_stacktrace_map.c |  4 ++--
 .../selftests/bpf/progs/test_tcpnotify_kern.c |  4 ++--
 .../selftests/bpf/progs/test_xdp_bpf2bpf.c    |  4 ++--
 14 files changed, 62 insertions(+), 40 deletions(-)

--
2.30.2

Looks good. Applied to bpf-next, thanks.