[RFC][PATCH 1/4] selftests: timers: Add leap-second timer edge testing to leap-a-day.c

[John Stultz]

Prarit reported an issue w/ timers around the leapsecond, where
a timer set for Midnight UTC (00:00:00) might fire a second early
right before the leapsecond (23:59:60 - though it appears as a
repeated 23:59:59) is applied.

So I've updated the leap-a-day.c test to integrate a similar
test, where we set a timer and check if it triggers at the
right time, and if the ntp state transition is managed
properly.

Currently this test will fail. But following patches correct
the issue.

Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Cc: Richard Cochran <richardcochran@xxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Jiri Bohac <jbohac@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
Reported-by: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
Reported-by: Prarit Bhargava <prarit@xxxxxxxxxx>
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
---
 tools/testing/selftests/timers/leap-a-day.c | 76 +++++++++++++++++++++++++++--
 1 file changed, 72 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/timers/leap-a-day.c b/tools/testing/selftests/timers/leap-a-day.c
index b8272e6..331c4f7 100644
--- a/tools/testing/selftests/timers/leap-a-day.c
+++ b/tools/testing/selftests/timers/leap-a-day.c
@@ -44,6 +44,7 @@
 #include <time.h>
 #include <sys/time.h>
 #include <sys/timex.h>
+#include <sys/errno.h>
 #include <string.h>
 #include <signal.h>
 #include <unistd.h>
@@ -63,6 +64,9 @@ static inline int ksft_exit_fail(void)
 #define NSEC_PER_SEC 1000000000ULL
 #define CLOCK_TAI 11
 
+time_t next_leap;
+int error_found;
+
 /* returns 1 if a <= b, 0 otherwise */
 static inline int in_order(struct timespec a, struct timespec b)
 {
@@ -134,6 +138,34 @@ void handler(int unused)
 	exit(0);
 }
 
+void sigalarm(int signo)
+{
+	struct timex tx;
+	char buf[26];
+	int ret;
+
+	tx.modes = 0;
+	ret = adjtimex(&tx);
+
+	ctime_r(&tx.time.tv_sec, buf);
+	buf[strlen(buf)-1] = 0; /*remove trailing\n */
+	printf("%s + %6ld us (%i)\t%s - TIMER FIRED\n",
+					buf,
+					tx.time.tv_usec,
+					tx.tai,
+					time_state_str(ret));
+
+	if (tx.time.tv_sec < next_leap) {
+		printf("Error: Early timer expiration!\n");
+		error_found = 1;
+	}
+	if (ret != TIME_WAIT) {
+		printf("Error: Incorrect NTP state?\n");
+		error_found = 1;
+	}
+}
+
+
 /* Test for known hrtimer failure */
 void test_hrtimer_failure(void)
 {
@@ -144,12 +176,19 @@ void test_hrtimer_failure(void)
 	clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, &target, NULL);
 	clock_gettime(CLOCK_REALTIME, &now);
 
-	if (!in_order(target, now))
+	if (!in_order(target, now)) {
 		printf("ERROR: hrtimer early expiration failure observed.\n");
+		error_found = 1;
+	}
 }
 
 int main(int argc, char **argv)
 {
+	timer_t tm1;
+	struct itimerspec its1;
+	struct sigevent se;
+	struct sigaction act;
+	int signum = SIGRTMAX;
 	int settime = 0;
 	int tai_time = 0;
 	int insert = 1;
@@ -191,6 +230,12 @@ int main(int argc, char **argv)
 	signal(SIGINT, handler);
 	signal(SIGKILL, handler);
 
+	/* Set up timer signal handler: */
+	sigfillset(&act.sa_mask);
+	act.sa_flags = 0;
+	act.sa_handler = sigalarm;
+	sigaction(signum, &act, NULL);
+
 	if (iterations < 0)
 		printf("This runs continuously. Press ctrl-c to stop\n");
 	else
@@ -201,7 +246,7 @@ int main(int argc, char **argv)
 		int ret;
 		struct timespec ts;
 		struct timex tx;
-		time_t now, next_leap;
+		time_t now;
 
 		/* Get the current time */
 		clock_gettime(CLOCK_REALTIME, &ts);
@@ -251,10 +296,27 @@ int main(int argc, char **argv)
 
 		printf("Scheduling leap second for %s", ctime(&next_leap));
 
+		/* Set up timer */
+		printf("Setting timer for %s", ctime(&next_leap));
+		memset(&se, 0, sizeof(se));
+		se.sigev_notify = SIGEV_SIGNAL;
+		se.sigev_signo = signum;
+		se.sigev_value.sival_int = 0;
+		if (timer_create(CLOCK_REALTIME, &se, &tm1) == -1) {
+			printf("Error: timer_create failed\n");
+			return ksft_exit_fail();
+		}
+		its1.it_value.tv_sec = next_leap;
+		its1.it_value.tv_nsec = 0;
+		its1.it_interval.tv_sec = 0;
+		its1.it_interval.tv_nsec = 0;
+		timer_settime(tm1, TIMER_ABSTIME, &its1, NULL);
+
 		/* Wake up 3 seconds before leap */
 		ts.tv_sec = next_leap - 3;
 		ts.tv_nsec = 0;
 
+
 		while (clock_nanosleep(CLOCK_REALTIME, TIMER_ABSTIME, &ts, NULL))
 			printf("Something woke us up, returning to sleep\n");
 
@@ -276,6 +338,7 @@ int main(int argc, char **argv)
 		while (now < next_leap + 2) {
 			char buf[26];
 			struct timespec tai;
+			int ret;
 
 			tx.modes = 0;
 			ret = adjtimex(&tx);
@@ -308,8 +371,13 @@ int main(int argc, char **argv)
 		/* Note if kernel has known hrtimer failure */
 		test_hrtimer_failure();
 
-		printf("Leap complete\n\n");
-
+		printf("Leap complete\n");
+		if (error_found) {
+			printf("Errors observed\n");
+			clear_time_state();
+			return ksft_exit_fail();
+		}
+		printf("\n");
 		if ((iterations != -1) && !(--iterations))
 			break;
 	}
-- 
1.9.1

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