selftests: futex: Expand timeout test

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

Signed-off-by: André Almeida <andrealmeid@collabora.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20210427135328.11013-3-andrealmeid@collabora.com

diff --git a/tools/testing/selftests/futex/functional/futex_wait_timeout.c b/tools/testing/selftests/futex/functional/futex_wait_timeout.c
index ee55e6d..1f8f6da 100644 (file)
--- 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;
 }