kselftests: set-timer-lat: test one-shot timers

PATCH New Greg Hackmann 1 participant 3 messages Jul 25, 2017

Subsystems (3)

Kselftest Timekeeping, clocksource core, NTP, alarmtimer High-resolution timers, timer wheel, clockevents

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Greg Hackmann

author

2017-07-25 21:37 UTC #0 lore raw

cover kselftests: set-timer-lat: test one-shot timers

This patchset expands set-timer-lat to cover one-shot timers. This is inspired by a recent regression in the -stable tree, which caused one-shot alarm timers to repeat at a 1 ns interval.

The first patch adjusts how early-firing timers are reported, so faulty kernels won't cause the test to spam the console with failure messages. The second patch actually adds the one-shot testcases.

Greg Hackmann (2):
kselftests: set-timer-lat: tweak reporting when timer fires early
kselftests: set-timer-lat: add one-shot timer test cases

 tools/testing/selftests/timers/set-timer-lat.c | 103 +++++++++++++++++++++----
 1 file changed, 90 insertions(+), 13 deletions(-)

Signature · 1 line

2.14.0.rc0.400.g1c36432dff-goog

Greg Hackmann

author

2017-07-25 21:37 UTC #1 lore raw

PATCH 1/2 kselftests: set-timer-lat: tweak reporting when timer fires early

Rather than printing an error inside the alarm signal handler, set a flag that we check later. This keeps the test from spamming the console every time the alarm fires early. It also fixes the test exiting with error code 0 if this was the only test failure.

Signed-off-by Greg Hackmann <[email protected]>

---
 tools/testing/selftests/timers/set-timer-lat.c | 33 +++++++++++++++++++-------
 1 file changed, 25 insertions(+), 8 deletions(-)

tools/testing/selftests/timers/set-timer-lat.c +25 -8

index 4fc98c5b0899..10c2e18737c0 100644
@@ -63,6 +63,7 @@ int alarmcount;
 int clock_id;
 struct timespec start_time;
 long long max_latency_ns;
+int timer_fired_early;
 
 char *clockstring(int clockid)
 {

@@ -115,12 +116,19 @@ void sigalarm(int signo)
 	delta_ns -= NSEC_PER_SEC * TIMER_SECS * alarmcount;
 
 	if (delta_ns < 0)
-		printf("%s timer fired early: FAIL\n", clockstring(clock_id));
+		timer_fired_early = 1;
 
 	if (delta_ns > max_latency_ns)
 		max_latency_ns = delta_ns;
 }
 
+void describe_timer(int flags)
+{
+	printf("%-22s %s ",
+			clockstring(clock_id),
+			flags ? "ABSTIME":"RELTIME");
+}
+
 int do_timer(int clock_id, int flags)
 {
 	struct sigevent se;

@@ -136,6 +144,7 @@ int do_timer(int clock_id, int flags)
 
 	max_latency_ns = 0;
 	alarmcount = 0;
+	timer_fired_early = 0;
 
 	err = timer_create(clock_id, &se, &tm1);
 	if (err) {

@@ -170,18 +179,26 @@ int do_timer(int clock_id, int flags)
 	while (alarmcount < 5)
 		sleep(1);
 
-	printf("%-22s %s max latency: %10lld ns : ",
-			clockstring(clock_id),
-			flags ? "ABSTIME":"RELTIME",
-			max_latency_ns);
+	describe_timer(flags);
+	printf("timer fired early: %7d : ", timer_fired_early);
+	if (!timer_fired_early) {
+		printf("[OK]\n");
+	} else {
+		printf("[FAILED]\n");
+		err = -1;
+	}
+
+	describe_timer(flags);
+	printf("max latency: %10lld ns : ", max_latency_ns);
 
 	timer_delete(tm1);
 	if (max_latency_ns < UNRESONABLE_LATENCY) {
 		printf("[OK]\n");
-		return 0;
+	} else {
+		printf("[FAILED]\n");
+		err = -1;
 	}
-	printf("[FAILED]\n");
-	return -1;
+	return err;
 }
 
 int main(void)

Signature · 1 line

2.14.0.rc0.400.g1c36432dff-goog

Greg Hackmann

author

2017-07-25 21:37 UTC #2 lore raw

PATCH 2/2 kselftests: set-timer-lat: add one-shot timer test cases

In reply to Greg Hackmann

These testcases are motivated by a recent alarmtimer regression, which caused one-shot CLOCK_{BOOTTIME,REALTIME}_ALARM timers to become periodic timers.

The new testcases are very similar to the existing testcases for repeating timers. But rather than waiting for 5 alarms, they wait for 5 seconds and verify that the alarm fired exactly once.

Signed-off-by Greg Hackmann <[email protected]>

---
 tools/testing/selftests/timers/set-timer-lat.c | 86 ++++++++++++++++++++++----
 1 file changed, 73 insertions(+), 13 deletions(-)

tools/testing/selftests/timers/set-timer-lat.c +73 ~~-13~~

index 10c2e18737c0..15434da23b04 100644
@@ -20,6 +20,7 @@
  */
 
 
+#include <errno.h>
 #include <stdio.h>
 #include <unistd.h>
 #include <time.h>

@@ -122,17 +123,17 @@ void sigalarm(int signo)
 		max_latency_ns = delta_ns;
 }
 
-void describe_timer(int flags)
+void describe_timer(int flags, int interval)
 {
-	printf("%-22s %s ",
+	printf("%-22s %s %s ",
 			clockstring(clock_id),
-			flags ? "ABSTIME":"RELTIME");
+			flags ? "ABSTIME":"RELTIME",
+			interval ? "PERIODIC":"ONE-SHOT");
 }
 
-int do_timer(int clock_id, int flags)
+int setup_timer(int clock_id, int flags, int interval, timer_t *tm1)
 {
 	struct sigevent se;
-	timer_t tm1;
 	struct itimerspec its1, its2;
 	int err;

@@ -146,7 +147,7 @@ int do_timer(int clock_id, int flags)
 	alarmcount = 0;
 	timer_fired_early = 0;
 
-	err = timer_create(clock_id, &se, &tm1);
+	err = timer_create(clock_id, &se, tm1);
 	if (err) {
 		if ((clock_id == CLOCK_REALTIME_ALARM) ||
 		    (clock_id == CLOCK_BOOTTIME_ALARM)) {

@@ -167,19 +168,23 @@ int do_timer(int clock_id, int flags)
 		its1.it_value.tv_sec = TIMER_SECS;
 		its1.it_value.tv_nsec = 0;
 	}
-	its1.it_interval.tv_sec = TIMER_SECS;
+	its1.it_interval.tv_sec = interval;
 	its1.it_interval.tv_nsec = 0;
 
-	err = timer_settime(tm1, flags, &its1, &its2);
+	err = timer_settime(*tm1, flags, &its1, &its2);
 	if (err) {
 		printf("%s - timer_settime() failed\n", clockstring(clock_id));
 		return -1;
 	}
 
-	while (alarmcount < 5)
-		sleep(1);
+	return 0;
+}
 
-	describe_timer(flags);
+int check_timer_latency(int flags, int interval)
+{
+	int err = 0;
+
+	describe_timer(flags, interval);
 	printf("timer fired early: %7d : ", timer_fired_early);
 	if (!timer_fired_early) {
 		printf("[OK]\n");

@@ -188,10 +193,9 @@ int do_timer(int clock_id, int flags)
 		err = -1;
 	}
 
-	describe_timer(flags);
+	describe_timer(flags, interval);
 	printf("max latency: %10lld ns : ", max_latency_ns);
 
-	timer_delete(tm1);
 	if (max_latency_ns < UNRESONABLE_LATENCY) {
 		printf("[OK]\n");
 	} else {

@@ -201,6 +205,60 @@ int do_timer(int clock_id, int flags)
 	return err;
 }
 
+int check_alarmcount(int flags, int interval)
+{
+	describe_timer(flags, interval);
+	printf("count: %19d : ", alarmcount);
+	if (alarmcount == 1) {
+		printf("[OK]\n");
+		return 0;
+	}
+	printf("[FAILED]\n");
+	return -1;
+}
+
+int do_timer(int clock_id, int flags)
+{
+	timer_t tm1;
+	const int interval = TIMER_SECS;
+	int err;
+
+	err = setup_timer(clock_id, flags, interval, &tm1);
+	if (err)
+		return err;
+
+	while (alarmcount < 5)
+		sleep(1);
+
+	timer_delete(tm1);
+	return check_timer_latency(flags, interval);
+}
+
+int do_timer_oneshot(int clock_id, int flags)
+{
+	timer_t tm1;
+	const int interval = 0;
+	struct timeval timeout;
+	fd_set fds;
+	int err;
+
+	err = setup_timer(clock_id, flags, interval, &tm1);
+	if (err)
+		return err;
+
+	memset(&timeout, 0, sizeof(timeout));
+	timeout.tv_sec = 5;
+	FD_ZERO(&fds);
+	do {
+		err = select(FD_SETSIZE, &fds, NULL, NULL, &timeout);
+	} while (err == -1 && errno == EINTR);
+
+	timer_delete(tm1);
+	err = check_timer_latency(flags, interval);
+	err |= check_alarmcount(flags, interval);
+	return err;
+}
+
 int main(void)
 {
 	struct sigaction act;

@@ -226,6 +284,8 @@ int main(void)
 
 		ret |= do_timer(clock_id, TIMER_ABSTIME);
 		ret |= do_timer(clock_id, 0);
+		ret |= do_timer_oneshot(clock_id, TIMER_ABSTIME);
+		ret |= do_timer_oneshot(clock_id, 0);
 	}
 	if (ret)
 		return ksft_exit_fail();

Signature · 1 line

2.14.0.rc0.400.g1c36432dff-goog