Improve futex timeout testing by checking all the operations that supports timeout and their available modes.

Signed-off-by: André Almeida andrealmeid@collabora.com --- .../futex/functional/futex_wait_timeout.c | 126 +++++++++++++++--- 1 file changed, 110 insertions(+), 16 deletions(-)

diff --git a/tools/testing/selftests/futex/functional/futex_wait_timeout.c b/tools/testing/selftests/futex/functional/futex_wait_timeout.c index ee55e6d389a3..1f8f6daaf1e7 100644 --- a/tools/testing/selftests/futex/functional/futex_wait_timeout.c +++ b/tools/testing/selftests/futex/functional/futex_wait_timeout.c @@ -11,21 +11,18 @@ * * HISTORY * 2009-Nov-6: Initial version by Darren Hart dvhart@linux.intel.com + * 2021-Apr-26: More test cases by André Almeida andrealmeid@collabora.com * *****************************************************************************/

-#include <errno.h> -#include <getopt.h> -#include <stdio.h> -#include <stdlib.h> -#include <string.h> -#include <time.h> +#include <pthread.h> #include "futextest.h" #include "logging.h"

#define TEST_NAME "futex-wait-timeout"

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

void usage(char *prog) { @@ -37,11 +34,67 @@ void usage(char *prog) VQUIET, VCRITICAL, VINFO); }

+/* + * Get a PI lock and hold it forever, so the main thread lock_pi will block + * and we can test the timeout + */ +void *get_pi_lock(void *arg) +{ + int ret; + volatile futex_t lock = 0; + + ret = futex_lock_pi(&futex_pi, NULL, 0, 0); + if (ret != 0) + error("futex_lock_pi failed\n", ret); + + /* Blocks forever */ + ret = futex_wait(&lock, 0, NULL, 0); + error("futex_wait failed\n", ret); + + return NULL; +} + +/* + * Check if the function returned the expected error + */ +static void test_timeout(int res, int *ret, char *test_name, int err) +{ + if (!res || errno != err) { + ksft_test_result_fail("%s returned %d\n", test_name, + res < 0 ? errno : res); + *ret = RET_FAIL; + } else { + ksft_test_result_pass("%s succeeds\n", test_name); + } +} + +/* + * Calculate absolute timeout and correct overflow + */ +static int futex_get_abs_timeout(clockid_t clockid, struct timespec *to, + long timeout_ns) +{ + if (clock_gettime(clockid, to)) { + error("clock_gettime failed\n", errno); + return errno; + } + + to->tv_nsec += timeout_ns; + + if (to->tv_nsec >= 1000000000) { + to->tv_sec++; + to->tv_nsec -= 1000000000; + } + + return 0; +} + int main(int argc, char *argv[]) { futex_t f1 = FUTEX_INITIALIZER; - struct timespec to; int res, ret = RET_PASS; + struct timespec to; + pthread_t thread; int c;

while ((c = getopt(argc, argv, "cht:v:")) != -1) { @@ -65,22 +118,63 @@ int main(int argc, char *argv[]) }

ksft_print_header(); - ksft_set_plan(1); + ksft_set_plan(7); ksft_print_msg("%s: Block on a futex and wait for timeout\n", basename(argv[0])); ksft_print_msg("\tArguments: timeout=%ldns\n", timeout_ns);

- /* initialize timeout */ + pthread_create(&thread, NULL, get_pi_lock, NULL); + + /* initialize relative timeout */ to.tv_sec = 0; to.tv_nsec = timeout_ns;

- info("Calling futex_wait on f1: %u @ %p\n", f1, &f1); - res = futex_wait(&f1, f1, &to, FUTEX_PRIVATE_FLAG); - if (!res || errno != ETIMEDOUT) { - fail("futex_wait returned %d\n", ret < 0 ? errno : ret); - ret = RET_FAIL; - } + res = futex_wait(&f1, f1, &to, 0); + test_timeout(res, &ret, "futex_wait relative", ETIMEDOUT); + + /* FUTEX_WAIT_BITSET with CLOCK_REALTIME */ + if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns)) + return RET_FAIL; + res = futex_wait_bitset(&f1, f1, &to, 1, FUTEX_CLOCK_REALTIME); + test_timeout(res, &ret, "futex_wait_bitset realtime", ETIMEDOUT); + + /* FUTEX_WAIT_BITSET with CLOCK_MONOTONIC */ + if (futex_get_abs_timeout(CLOCK_MONOTONIC, &to, timeout_ns)) + return RET_FAIL; + res = futex_wait_bitset(&f1, f1, &to, 1, 0); + test_timeout(res, &ret, "futex_wait_bitset monotonic", ETIMEDOUT); + + /* FUTEX_WAIT_REQUEUE_PI with CLOCK_REALTIME */ + if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns)) + return RET_FAIL; + res = futex_wait_requeue_pi(&f1, f1, &futex_pi, &to, FUTEX_CLOCK_REALTIME); + test_timeout(res, &ret, "futex_wait_requeue_pi realtime", ETIMEDOUT); + + /* FUTEX_WAIT_REQUEUE_PI with CLOCK_MONOTONIC */ + if (futex_get_abs_timeout(CLOCK_MONOTONIC, &to, timeout_ns)) + return RET_FAIL; + res = futex_wait_requeue_pi(&f1, f1, &futex_pi, &to, 0); + test_timeout(res, &ret, "futex_wait_requeue_pi monotonic", ETIMEDOUT); + + /* + * FUTEX_LOCK_PI with CLOCK_REALTIME + * Due to historical reasons, FUTEX_LOCK_PI supports only realtime + * clock, but requires the caller to not set CLOCK_REALTIME flag. + * + * If you call FUTEX_LOCK_PI with a monotonic clock, it'll be + * interpreted as a realtime clock, and (unless you mess your machine's + * time or your time machine) the monotonic clock value is always + * smaller than realtime and the syscall will timeout immediately. + */ + if (futex_get_abs_timeout(CLOCK_REALTIME, &to, timeout_ns)) + return RET_FAIL; + res = futex_lock_pi(&futex_pi, &to, 0, 0); + test_timeout(res, &ret, "futex_lock_pi realtime", ETIMEDOUT); + + /* Test operations that don't support FUTEX_CLOCK_REALTIME */ + res = futex_lock_pi(&futex_pi, NULL, 0, FUTEX_CLOCK_REALTIME); + test_timeout(res, &ret, "futex_lock_pi invalid timeout flag", ENOSYS);

- print_result(TEST_NAME, ret); + ksft_print_cnts(); return ret; }