Observed occassional failures in the futex_wait_timeout test:

ok 1 futex_wait relative succeeds ok 2 futex_wait_bitset realtime succeeds ok 3 futex_wait_bitset monotonic succeeds ok 4 futex_wait_requeue_pi realtime succeeds ok 5 futex_wait_requeue_pi monotonic succeeds not ok 6 futex_lock_pi realtime returned 0 ......

The test expects the child thread to complete some steps before the parent thread gets to run. There is an implicit expectation of the order of invocation of futex_lock_pi between the child thread and the parent thread. Make this order explicit. If the order is not met, the futex_lock_pi call in the parent thread succeeds and will not timeout.

Fixes: f4addd54b161 ("selftests: futex: Expand timeout test") Signed-off-by: Nysal Jan K.A nysal@linux.ibm.com --- .../selftests/futex/functional/futex_wait_timeout.c | 7 +++++++ 1 file changed, 7 insertions(+)

diff --git a/tools/testing/selftests/futex/functional/futex_wait_timeout.c b/tools/testing/selftests/futex/functional/futex_wait_timeout.c index 3651ce17beeb..d183f878360b 100644 --- a/tools/testing/selftests/futex/functional/futex_wait_timeout.c +++ b/tools/testing/selftests/futex/functional/futex_wait_timeout.c @@ -24,6 +24,7 @@

static long timeout_ns = 100000; /* 100us default timeout */ static futex_t futex_pi; +static pthread_barrier_t barrier;

void usage(char *prog) { @@ -48,6 +49,8 @@ void *get_pi_lock(void *arg) if (ret != 0) error("futex_lock_pi failed\n", ret);

+ pthread_barrier_wait(&barrier); + /* Blocks forever */ ret = futex_wait(&lock, 0, NULL, 0); error("futex_wait failed\n", ret); @@ -130,6 +133,7 @@ int main(int argc, char *argv[]) basename(argv[0])); ksft_print_msg("\tArguments: timeout=%ldns\n", timeout_ns);

+ pthread_barrier_init(&barrier, NULL, 2); pthread_create(&thread, NULL, get_pi_lock, NULL);

/* initialize relative timeout */ @@ -163,6 +167,9 @@ int main(int argc, char *argv[]) res = futex_wait_requeue_pi(&f1, f1, &futex_pi, &to, 0); test_timeout(res, &ret, "futex_wait_requeue_pi monotonic", ETIMEDOUT);

+ /* Wait until the other thread calls futex_lock_pi() */ + pthread_barrier_wait(&barrier); + pthread_barrier_destroy(&barrier); /* * FUTEX_LOCK_PI with CLOCK_REALTIME * Due to historical reasons, FUTEX_LOCK_PI supports only realtime