selftests/timers/posix-timers: Validate SIGEV_NONE

Posix timers with a delivery mode of SIGEV_NONE deliver no signals but the
remaining expiry time must be readable via timer_gettime() for both one
shot and interval timers.

That's implemented correctly for regular posix timers but broken for posix
CPU timers.

Add a self test so the fixes can be verified.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>

tools/testing/selftests/timers/posix_timers.c

@@ -11,6 +11,7 @@
 #include <sys/types.h>
 #include <stdio.h>
 #include <signal.h>
+#include <stdint.h>
 #include <string.h>
 #include <unistd.h>
 #include <time.h>
@@ -20,6 +21,7 @@
 
 #define DELAY 2
 #define USECS_PER_SEC 1000000
+#define NSECS_PER_SEC 1000000000
 
 static void __fatal_error(const char *test, const char *name, const char *what)
 {
@@ -438,10 +440,57 @@ static void check_delete(void)
 	ksft_test_result(!tsig.signals, "check_delete\n");
 }
 
+static inline int64_t calcdiff_ns(struct timespec t1, struct timespec t2)
+{
+	int64_t diff;
+
+	diff = NSECS_PER_SEC * (int64_t)((int) t1.tv_sec - (int) t2.tv_sec);
+	diff += ((int) t1.tv_nsec - (int) t2.tv_nsec);
+	return diff;
+}
+
+static void check_sigev_none(int which, const char *name)
+{
+	struct timespec start, now;
+	struct itimerspec its;
+	struct sigevent sev;
+	timer_t timerid;
+
+	memset(&sev, 0, sizeof(sev));
+	sev.sigev_notify = SIGEV_NONE;
+
+	if (timer_create(which, &sev, &timerid))
+		fatal_error(name, "timer_create()");
+
+	/* Start the timer to expire in 100ms and 100ms intervals */
+	its.it_value.tv_sec = 0;
+	its.it_value.tv_nsec = 100000000;
+	its.it_interval.tv_sec = 0;
+	its.it_interval.tv_nsec = 100000000;
+	timer_settime(timerid, 0, &its, NULL);
+
+	if (clock_gettime(which, &start))
+		fatal_error(name, "clock_gettime()");
+
+	do {
+		if (clock_gettime(which, &now))
+			fatal_error(name, "clock_gettime()");
+	} while (calcdiff_ns(now, start) < NSECS_PER_SEC);
+
+	if (timer_gettime(timerid, &its))
+		fatal_error(name, "timer_gettime()");
+
+	if (timer_delete(timerid))
+		fatal_error(name, "timer_delete()");
+
+	ksft_test_result(its.it_value.tv_sec || its.it_value.tv_nsec,
+			 "check_sigev_none %s\n", name);
+}
+
 int main(int argc, char **argv)
 {
 	ksft_print_header();
-	ksft_set_plan(10);
+	ksft_set_plan(12);
 
 	ksft_print_msg("Testing posix timers. False negative may happen on CPU execution \n");
 	ksft_print_msg("based timers if other threads run on the CPU...\n");
@@ -467,6 +516,8 @@ int main(int argc, char **argv)
 	check_sig_ign(1);
 	check_rearm();
 	check_delete();
+	check_sigev_none(CLOCK_MONOTONIC, "CLOCK_MONOTONIC");
+	check_sigev_none(CLOCK_PROCESS_CPUTIME_ID, "CLOCK_PROCESS_CPUTIME_ID");
 
 	ksft_finished();
 }