Fix timing errors in futex_requeue_pi_signal_restart

Add a delay after the first signal to give the waiter time to restart
and block on f1. Increase the delay to 1ms from 100us in the various
loops. Change the restul from RET_ERROR to RET_FAIL where appropriate.

Signed-off-by: Darren Hart <dvhltc@us.ibm.com>

1 files changed, 13 insertions, 7 deletions

diff --git a/functional/futex_requeue_pi_signal_restart.c b/functional/futex_requeue_pi_signal_restart.c
index d4271b5..8140c79 100644
--- a/functional/futex_requeue_pi_signal_restart.c
+++ b/functional/futex_requeue_pi_signal_restart.c
@@ -44,6 +44,8 @@
 #include "futextest.h"
 #include "logging.h"
 
+#define DELAY_US 1000
+
 futex_t f1 = FUTEX_INITIALIZER;
 futex_t f2 = FUTEX_INITIALIZER;
 atomic_t requeued = ATOMIC_INITIALIZER;
@@ -115,11 +117,12 @@ void *waiterfn(void *arg)
 	old_val = f1;
 	res = futex_wait_requeue_pi(&f1, old_val, &(f2), NULL, FUTEX_PRIVATE_FLAG);
 	if (!requeued.val || errno != EWOULDBLOCK) {
-		error("unexpected return from futex_wait_requeue_pi\n", errno);
+		fail("unexpected return from futex_wait_requeue_pi: %d (%s)\n",
+		     res, strerror(errno));
 		info("w2:futex: %x\n", f2);
 		if (!res)
 			futex_unlock_pi(&f2, FUTEX_PRIVATE_FLAG);
-		waiter_ret = RET_ERROR;
+		waiter_ret = RET_FAIL;
 	}
 
 	info("Waiter exiting with %d\n", waiter_ret);
@@ -177,15 +180,17 @@ int main(int argc, char *argv[])
 
 	/* wait for the waiter to start running, then give it time to block */
 	while (!waiter_running.val)
-		usleep(100);
-	usleep(100);
+		usleep(DELAY_US);
+	usleep(DELAY_US);
 
 	/* 
 	 * signal the waiter before requeue, waiter should automatically
-	 * restart futex_wait_requeue_pi() in the kernel.
+	 * restart futex_wait_requeue_pi() in the kernel. Wait for the waiter
+	 * to block on f1 again.
 	 */
 	info("Issuing SIGUSR1 to waiter\n"); 
 	pthread_kill(waiter, SIGUSR1);
+	usleep(DELAY_US);
 
 	info("Waking waiter via FUTEX_CMP_REQUEUE_PI\n");
 	while (1) {
@@ -196,7 +201,8 @@ int main(int argc, char *argv[])
 			break;
 		error("Waiter was not ready for requeue. First signal was "
 		      "delivered too early\n", 0);
-		usleep(100);
+		ret = RET_ERROR;
+		usleep(DELAY_US);
 	}
 	if (res < 0) {
 		error("FUTEX_CMP_REQUEUE_PI failed\n", errno);
@@ -214,7 +220,7 @@ int main(int argc, char *argv[])
 	pthread_kill(waiter, SIGUSR1);
 
 	/* give the signal time to get to the waiter */
-	usleep(100);
+	usleep(DELAY_US);
 	info("Calling FUTEX_UNLOCK_PI on mutex=%x @ %p\n", f2, &f2);
 	futex_unlock_pi(&f2, FUTEX_PRIVATE_FLAG);