Fix the sem_timedwait(3) test.

The recent clock_getres(2) changes made it so that clock_getres(2) returns
the granularity of the active timecounter.  This is usually much finer
than that of hardclock(9), so we can no longer use clock_getres(2) to
fudge our upper timeout return bound.  The test is failing because it
thinks our sem_timedwait(3) call is returning with too much latency.

We can still get the hardclock(9) granularity via the kern.clockrate
sysctl(2), though, so just use that to fudge the upper bound.

While here, we ought to be checking that we return after the requested
absolute timeout, not that we were asleep for a particular interval.

Breakage reported by mpi@.

ok mpi@

1 files changed, 25 insertions, 9 deletions

diff --git a/regress/lib/libpthread/semaphore/sem_timedwait/sem_timedwait.c b/regress/lib/libpthread/semaphore/sem_timedwait/sem_timedwait.c
index 203d41c5e61..dc39cea75a8 100644
--- a/regress/lib/libpthread/semaphore/sem_timedwait/sem_timedwait.c
+++ b/regress/lib/libpthread/semaphore/sem_timedwait/sem_timedwait.c
@@ -1,8 +1,11 @@
-/*	$OpenBSD: sem_timedwait.c,v 1.3 2018/04/27 11:31:17 pirofti Exp $	*/
+/*	$OpenBSD: sem_timedwait.c,v 1.4 2019/12/20 23:39:01 cheloha Exp $	*/
 /*
  * Martin Pieuchot <mpi@openbsd.org>, 2011. Public Domain.
  */
 
+#include <sys/types.h>
+#include <sys/sysctl.h>
+
 #include <err.h>
 #include <errno.h>
 #include <unistd.h>
@@ -29,8 +32,11 @@ int
 main(int argc, char **argv)
 {
 	pthread_t th;
+	struct clockinfo info;
 	struct sigaction sa;
-	struct timespec ts, ts2;
+	struct timespec delay, ts, ts2;
+	size_t infosize = sizeof(info);
+	int mib[] = { CTL_KERN, KERN_CLOCKRATE };
 
 	CHECKr(clock_gettime(CLOCK_REALTIME, &ts));
 	ts.tv_sec += 3;
@@ -76,13 +82,23 @@ main(int argc, char **argv)
 	CHECKn(sem_timedwait(&sem, &ts));
 	ASSERT(errno == ETIMEDOUT);
 	CHECKr(clock_gettime(CLOCK_REALTIME, &ts2));
-	if (timespeccmp(&ts, &ts2, < ))
-		timespecsub(&ts2, &ts, &ts);
-	else
-		timespecsub(&ts, &ts2, &ts);
-	CHECKr(clock_getres(CLOCK_REALTIME, &ts2));
-	timespecadd(&ts2, &ts2, &ts2);	/* 2 * resolution slop */
-	ASSERT(timespeccmp(&ts, &ts2, < ));
+
+	fprintf(stderr, "timeout: expected %lld.%09ld actual %lld.%09ld\n",
+	    ts.tv_sec, ts.tv_nsec, ts2.tv_sec, ts2.tv_nsec);
+
+	/* Check that we don't return early. */
+	ASSERT(timespeccmp(&ts, &ts2, <=));
+
+	/*
+	 * Check that we don't return unusually late.  Something might be
+	 * off if the wait returns more than two ticks after our timeout.
+	 */
+	CHECKr(sysctl(mib, 2, &info, &infosize, NULL, 0));
+	delay.tv_sec = 0;
+	delay.tv_nsec = info.tick * 1000;	/* usecs -> nsecs */
+	timespecadd(&delay, &delay, &delay);	/* up to two ticks of delay */
+	timespecadd(&ts, &delay, &ts);
+	ASSERT(timespeccmp(&ts2, &ts, <=));
 
 	CHECKe(sem_destroy(&sem));