On Thu, Aug 28, 2025 at 1:15 AM Feng Yang <yangfeng59949@xxxxxxx> wrote:
>
> From: Feng Yang <yangfeng@xxxxxxxxxx>
>
> The error message printed here only uses the previous err value,
> which results in it being printed as 0.
> When bpf_map__attach_struct_ops encounters an error,
> it uses libbpf_err_ptr(err) to set errno = -err and returns NULL.
Yes, but libbpf_get_error() is better.
And decimal number is preferred as ASSERT_OK_PTR() macro does.
pw-bot: cr
> Therefore, strerror(errno) can be used to fix this issue.
>
> Fix before:
> run_subtest:FAIL:1019 bpf_map__attach_struct_ops failed for map pro_epilogue: err=0
>
> Fix after:
> run_subtest:FAIL:1019 bpf_map__attach_struct_ops failed for map pro_epilogue: Bad file descriptor
>
> Signed-off-by: Feng Yang <yangfeng@xxxxxxxxxx>
> ---
> tools/testing/selftests/bpf/test_loader.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/test_loader.c b/tools/testing/selftests/bpf/test_loader.c
> index f361c8aa1daf..686a7d7f87b1 100644
> --- a/tools/testing/selftests/bpf/test_loader.c
> +++ b/tools/testing/selftests/bpf/test_loader.c
> @@ -1008,8 +1008,8 @@ void run_subtest(struct test_loader *tester,
> }
> link = bpf_map__attach_struct_ops(map);
> if (!link) {
> - PRINT_FAIL("bpf_map__attach_struct_ops failed for map %s: err=%d\n",
> - bpf_map__name(map), err);
> + PRINT_FAIL("bpf_map__attach_struct_ops failed for map %s: %s\n",
> + bpf_map__name(map), strerror(errno));
> goto tobj_cleanup;
> }
> links[links_cnt++] = link;
> --
> 2.27.0
>
