Re: [PATCH] kselftest: Fix vdso_test_abi return status

Shuah Khan
2022-01-27T23:18:14Z

On 1/26/22 5:26 AM, Vincenzo Frascino wrote:
> vdso_test_abi contains a batch of tests that verify the validity of the
> vDSO ABI.
>
> When a vDSO symbol is not found the relevant test is skipped reporting
> KSFT_SKIP. All the tests return values are then added in a single
> variable which is checked to verify failures. This approach can have
> side effects which result in reporting the wrong kselftest exit status.
>
> Fix vdso_test_abi verifying the return code of each test separately.
>
> Cc: Shuah Khan <shuah@kernel.org>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Reported-by: Cristian Marussi <cristian.marussi@arm.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> ---
> tools/testing/selftests/vDSO/vdso_test_abi.c | 27 +++++++++++---------
> 1 file changed, 15 insertions(+), 12 deletions(-)
>
> diff --git a/tools/testing/selftests/vDSO/vdso_test_abi.c b/tools/testing/selftests/vDSO/vdso_test_abi.c
> index 3d603f1394af..3a4efb91b9b2 100644
> --- a/tools/testing/selftests/vDSO/vdso_test_abi.c
> +++ b/tools/testing/selftests/vDSO/vdso_test_abi.c
> @@ -184,10 +184,12 @@ static inline int vdso_test_clock(clockid_t clock_id)
> return ret0;
> }
>
> +#define VDSO_TESTS_MAX 9
> +
> int main(int argc, char **argv)
> {
> unsigned long sysinfo_ehdr = getauxval(AT_SYSINFO_EHDR);
> - int ret;
> + int ret[VDSO_TESTS_MAX] = {0};
>
> if (!sysinfo_ehdr) {
> printf("AT_SYSINFO_EHDR is not present!\n");
> @@ -201,44 +203,45 @@ int main(int argc, char **argv)
>
> vdso_init_from_sysinfo_ehdr(getauxval(AT_SYSINFO_EHDR));
>
> - ret = vdso_test_gettimeofday();
> + ret[0] = vdso_test_gettimeofday();
>
> #if _POSIX_TIMERS > 0
>
> #ifdef CLOCK_REALTIME
> - ret += vdso_test_clock(CLOCK_REALTIME);
> + ret[1] = vdso_test_clock(CLOCK_REALTIME);
> #endif
>
> #ifdef CLOCK_BOOTTIME
> - ret += vdso_test_clock(CLOCK_BOOTTIME);
> + ret[2] = vdso_test_clock(CLOCK_BOOTTIME);
> #endif
>
> #ifdef CLOCK_TAI
> - ret += vdso_test_clock(CLOCK_TAI);
> + ret[3] = vdso_test_clock(CLOCK_TAI);
> #endif
>
> #ifdef CLOCK_REALTIME_COARSE
> - ret += vdso_test_clock(CLOCK_REALTIME_COARSE);
> + ret[4] = vdso_test_clock(CLOCK_REALTIME_COARSE);
> #endif
>
> #ifdef CLOCK_MONOTONIC
> - ret += vdso_test_clock(CLOCK_MONOTONIC);
> + ret[5] = vdso_test_clock(CLOCK_MONOTONIC);
> #endif
>
> #ifdef CLOCK_MONOTONIC_RAW
> - ret += vdso_test_clock(CLOCK_MONOTONIC_RAW);
> + ret[6] = vdso_test_clock(CLOCK_MONOTONIC_RAW);
> #endif
>
> #ifdef CLOCK_MONOTONIC_COARSE
> - ret += vdso_test_clock(CLOCK_MONOTONIC_COARSE);
> + ret[7] = vdso_test_clock(CLOCK_MONOTONIC_COARSE);
> #endif
>
> #endif
>
> - ret += vdso_test_time();
> + ret[8] = vdso_test_time();
>
> - if (ret > 0)
> - return KSFT_FAIL;
> + for (int i = 0; i < VDSO_TESTS_MAX; i++)
> + if (ret[i] == KSFT_FAIL)
> + return KSFT_FAIL;
>
> return KSFT_PASS;
> }
>

You can use the ksft_* counts interfaces for this instead of adding
counts here. ksft_test_result_*() can be used to increment the right
result counters and then print counts at the end.

Either if there is a failure in any of the tests it will be fail with
clear indication on which tests failed. vdso_test_clock() test for
example is reporting false positives by overriding the Skip return
with a pass.

thanks,
-- Shuah