Re: [PATCH bpf-next] selftests/bpf: Skip test when perf_event_open returns EOPNOTSUPP

[Yonghong Song <yonghong.song@linux.dev>]

On 4/1/24 5:33 AM, Pu Lehui wrote:
> From: Pu Lehui <pulehui@huawei.com>
>
> For the bpf selftest, the semantics of perf_event_open returning ENOENT
> and EOPNOTSUPP imply that continuing the test is meaningless. Let’s skip
> test when perf_event_open returns EOPNOTSUPP, which has already been
> skipped in other test cases.

Could you explain when EOPNOTSUPP is returned for these two tests?
Is this riscv specific? If the EOPNOTSUPP is returned due to missing
config in tools/testing/selftests/bpf/config, we should add that to
ensure the test can execute properly.

>
> Signed-off-by: Pu Lehui <pulehui@huawei.com>
> ---
>   tools/testing/selftests/bpf/prog_tests/send_signal.c            | 2 +-
>   .../testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c  | 2 +-
>   2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/send_signal.c b/tools/testing/selftests/bpf/prog_tests/send_signal.c
> index b15b343ebb6b..920aee41bd58 100644
> --- a/tools/testing/selftests/bpf/prog_tests/send_signal.c
> +++ b/tools/testing/selftests/bpf/prog_tests/send_signal.c
> @@ -179,7 +179,7 @@ static void test_send_signal_nmi(bool signal_thread)
>   	pmu_fd = syscall(__NR_perf_event_open, &attr, 0 /* pid */,
>   			 -1 /* cpu */, -1 /* group_fd */, 0 /* flags */);
>   	if (pmu_fd == -1) {
> -		if (errno == ENOENT) {
> +		if (errno == ENOENT || errno == EOPNOTSUPP) {
>   			printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n",
>   			       __func__);
>   			test__skip();
> diff --git a/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c b/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c
> index 5db9eec24b5b..0832fd787457 100644
> --- a/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c
> +++ b/tools/testing/selftests/bpf/prog_tests/stacktrace_build_id_nmi.c
> @@ -35,7 +35,7 @@ void test_stacktrace_build_id_nmi(void)
>   	pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
>   			 0 /* cpu 0 */, -1 /* group id */,
>   			 0 /* flags */);
> -	if (pmu_fd < 0 && errno == ENOENT) {
> +	if (pmu_fd < 0 && (errno == ENOENT || errno == EOPNOTSUPP)) {
>   		printf("%s:SKIP:no PERF_COUNT_HW_CPU_CYCLES\n", __func__);
>   		test__skip();
>   		goto cleanup;