From: Feng Yang yangfeng@kylinos.cn

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. Therefore, Using -errno can 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: err=-9

Signed-off-by: Feng Yang yangfeng@kylinos.cn --- Changes in v3: - Use -errno here directly, thanks: Andrii Nakryiko. - Link to v2: https://lore.kernel.org/all/20250829014125.198653-1-yangfeng59949@163.com/ --- Changes in v2: - Use libbpf_get_error, thanks: Alexei Starovoitov. - Link to v1: https://lore.kernel.org/all/20250828081507.1380218-1-yangfeng59949@163.com/ --- tools/testing/selftests/bpf/test_loader.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/test_loader.c b/tools/testing/selftests/bpf/test_loader.c index 78423cf89e01..33d59c093a27 100644 --- a/tools/testing/selftests/bpf/test_loader.c +++ b/tools/testing/selftests/bpf/test_loader.c @@ -1083,7 +1083,7 @@ 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); + bpf_map__name(map), -errno); goto tobj_cleanup; } links[links_cnt++] = link;