netdev - Re: [PATCH bpf-next 0/3] Add new-style bpf_object_

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Date:   Thu, 3 Oct 2019 22:33:34 -0700
From:   Andrii Nakryiko <andrii.nakryiko@...il.com>
To:     Andrii Nakryiko <andriin@...com>
Cc:     bpf <bpf@...r.kernel.org>, Networking <netdev@...r.kernel.org>,
        Alexei Starovoitov <ast@...com>,
        Daniel Borkmann <daniel@...earbox.net>,
        Kernel Team <kernel-team@...com>
Subject: Re: [PATCH bpf-next 0/3] Add new-style bpf_object__open APIs

On Thu, Oct 3, 2019 at 10:29 PM Andrii Nakryiko <andriin@...com> wrote:
>
> Add bpf_object__open_file() and bpf_object__open_mem() APIs that use a new
> approach to providing future-proof non-ABI-breaking API changes. It relies on
> APIs accepting optional self-describing "opts" struct, containing its own
> size, filled out and provided by potentially outdated (as well as
> newer-than-libbpf) user application. A set of internal helper macros
> (OPTS_VALID, OPTS_HAS, and OPTS_GET) streamline and simplify a graceful
> handling forward and backward compatibility for user applications dynamically
> linked against different versions of libbpf shared library.
>
> Users of libbpf are provided with convenience macro LIBBPF_OPTS that takes
> care of populating correct structure size and zero-initializes options struct,
> which helps avoid obscure issues of unitialized padding. Uninitialized padding
> in a struct might turn into garbage-populated new fields understood by future
> versions of libbpf.
>
> Patch #3 switches two of test_progs' tests to use new APIs as a validation
> that they work as expected.
>
> v1->v2:
> - use better approach for tracking last field in opts struct;
> - convert few tests to new APIs for validation;
> - fix bug with using offsetof(last_field) instead of offsetofend(last_field).
>
> Andrii Nakryiko (3):
>   libbpf: stop enforcing kern_version, populate it for users
>   libbpf: add bpf_object__open_{file,mem} w/ extensible opts
>   selftests/bpf: switch tests to new bpf_object__open_{file,mem}() APIs
>
>  tools/lib/bpf/libbpf.c                        | 128 +++++++++---------
>  tools/lib/bpf/libbpf.h                        |  38 +++++-
>  tools/lib/bpf/libbpf.map                      |   3 +
>  tools/lib/bpf/libbpf_internal.h               |  32 +++++
>  tools/testing/selftests/bpf/Makefile          |   2 +-
>  .../selftests/bpf/prog_tests/attach_probe.c   |  42 +++++-
>  .../bpf/prog_tests/reference_tracking.c       |   7 +-
>  .../selftests/bpf/progs/test_attach_probe.c   |   1 -
>  .../bpf/progs/test_get_stack_rawtp.c          |   1 -
>  .../selftests/bpf/progs/test_perf_buffer.c    |   1 -
>  .../selftests/bpf/progs/test_stacktrace_map.c |   1 -
>  11 files changed, 176 insertions(+), 80 deletions(-)
>
> --
> 2.17.1
>

Sorry for the spam! Forgot to bump to v2 in subject prefix, re-sending
v2 with correct prefix.