Re: [PATCH bpf-next v5 0/3] libbpf: use func name when pinning programs with LIBBPF_STRICT_SEC_NAME

On Thu, Oct 21, 2021 at 2:48 PM Stanislav Fomichev [off-list ref] wrote:

Commit 15669e1dcd75 ("selftests/bpf: Normalize all the rest SEC() uses")
broke flow dissector tests. With the strict section names, bpftool isn't
able to pin all programs of the objects (all section names are the
same now). To bring it back to life let's do the following:

- teach libbpf to pin by func name with LIBBPF_STRICT_SEC_NAME
- enable strict mode in bpftool (breaking cli change)
- fix custom flow_dissector loader to use strict mode
- fix flow_dissector tests to use new pin names (func vs sec)

v5:
- get rid of error when retrying with '/' (Quentin Monnet)

v4:
- fix comment spelling (Quentin Monnet)
- retry progtype without / (Quentin Monnet)

v3:
- clarify program pinning in LIBBPF_STRICT_SEC_NAME,
  for real this time (Andrii Nakryiko)
- fix possible segfault in __bpf_program__pin_name (Andrii Nakryiko)

v2:
- add github issue (Andrii Nakryiko)
- remove sec_name from bpf_program.pin_name comment (Andrii Nakryiko)
- add cover letter (Andrii Nakryiko)

Stanislav Fomichev (3):
  libbpf: use func name when pinning programs with
    LIBBPF_STRICT_SEC_NAME
  bpftool: conditionally append / to the progtype
  selftests/bpf: fix flow dissector tests

I've applied patches #1 and #3, as they have to happen regardless of
how bpftool incompatibility is going to be handled. Please see
comments from John about bpftool. I think we should try to preserve
bpftool's backwards compatibility, or at the very least give users
some way to fall back to non-strict mode during the transition period.
I trust you, John and Quentin will figure out the best way forward
there.

Also, please move this flow_dissector_load selftest into test_progs,
so that we exercise it regularly.

 tools/bpf/bpftool/main.c                      |  4 +++
 tools/bpf/bpftool/prog.c                      | 35 ++++++++++---------
 tools/lib/bpf/libbpf.c                        | 13 +++++--
 tools/lib/bpf/libbpf_legacy.h                 |  3 ++
 .../selftests/bpf/flow_dissector_load.c       | 18 ++++++----
 .../selftests/bpf/flow_dissector_load.h       | 10 ++----
 .../selftests/bpf/test_flow_dissector.sh      | 10 +++---
 7 files changed, 55 insertions(+), 38 deletions(-)

--
2.33.0.1079.g6e70778dc9-goog