Re: [PATCH bpf-next 0/8] PROG_TEST_RUN support for sk_lookup programs

[Andrii Nakryiko <andrii.nakryiko@gmail.com>]

On Tue, Feb 16, 2021 at 2:58 AM Lorenz Bauer <lmb@cloudflare.com> wrote:
>
> We don't have PROG_TEST_RUN support for sk_lookup programs at the
> moment. So far this hasn't been a problem, since we can run our
> tests in a separate network namespace. For benchmarking it's nice
> to have PROG_TEST_RUN, so I've gone and implemented it.
>
> Multiple sk_lookup programs can be attached at once to the same
> netns. This can't be expressed with the current PROG_TEST_RUN
> API, so I'm proposing to extend it with an array of prog_fd.
>
> Patches 1-2 are clean ups. Patches 3-4 add the new UAPI and
> implement PROG_TEST_RUN for sk_lookup. Patch 5 adds a new
> function to libbpf to access multi prog tests. Patches 6-8 add
> tests.
>
> Andrii, for patch 4 I decided on the following API:
>
>     int bpf_prog_test_run_array(__u32 *prog_fds, __u32 prog_fds_cnt,
>                                 struct bpf_test_run_opts *opts)
>
> To be consistent with the rest of libbpf it would be better
> to take int *prog_fds, but I think then the function would have to
> convert the array to account for platforms where
>
>     sizeof(int) != sizeof(__u32)

Curious, is there any supported architecture where this is not the
case? I think it's fine to be consistent, tbh, and use int. Worst
case, in some obscure architecture we'd need to create a copy of an
array. Doesn't seem like a big deal (and highly unlikely anyways).

>
> Please let me know what your preference is.
>
> Lorenz Bauer (8):
>   bpf: consolidate shared test timing code
>   bpf: add for_each_bpf_prog helper
>   bpf: allow multiple programs in BPF_PROG_TEST_RUN
>   bpf: add PROG_TEST_RUN support for sk_lookup programs
>   tools: libbpf: allow testing program types with multi-prog semantics
>   selftests: bpf: convert sk_lookup multi prog tests to PROG_TEST_RUN
>   selftests: bpf: convert sk_lookup ctx access tests to PROG_TEST_RUN
>   selftests: bpf: check that PROG_TEST_RUN repeats as requested
>
>  include/linux/bpf-netns.h                     |   2 +
>  include/linux/bpf.h                           |  24 +-
>  include/linux/filter.h                        |   4 +-
>  include/uapi/linux/bpf.h                      |  11 +-
>  kernel/bpf/net_namespace.c                    |   2 +-
>  kernel/bpf/syscall.c                          |  73 +++++-
>  net/bpf/test_run.c                            | 230 +++++++++++++-----
>  net/core/filter.c                             |   1 +
>  tools/include/uapi/linux/bpf.h                |  11 +-
>  tools/lib/bpf/bpf.c                           |  16 +-
>  tools/lib/bpf/bpf.h                           |   3 +
>  tools/lib/bpf/libbpf.map                      |   1 +
>  .../selftests/bpf/prog_tests/prog_run_xattr.c |  51 +++-
>  .../selftests/bpf/prog_tests/sk_lookup.c      | 172 +++++++++----
>  .../selftests/bpf/progs/test_sk_lookup.c      |  62 +++--
>  15 files changed, 499 insertions(+), 164 deletions(-)
>
> --
> 2.27.0
>