[PATCH 3/3] selftests/timers: Test timer_gettime() on a disarmed SIGEV_NONE timer

[Shashank Mohan Jain <jain.sm@gmail.com>]

Arm a SIGEV_NONE timer for 100 seconds, disarm it and check that
timer_gettime() reports a zero it_value.

Run the test for CLOCK_MONOTONIC, where it fails without the previous
patch, and for CLOCK_PROCESS_CPUTIME_ID, where it passes with and
without it.

Assisted-by: LLM
Signed-off-by: Shashank Mohan Jain <jain.sm@gmail.com>
---
Prepared with Claude Code (Anthropic), model Claude Opus 5.5
(claude-opus-5-5).

 tools/testing/selftests/timers/posix_timers.c | 38 ++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/timers/posix_timers.c b/tools/testing/selftests/timers/posix_timers.c
index a92d4b9577..b6e56c08ba 100644
--- a/tools/testing/selftests/timers/posix_timers.c
+++ b/tools/testing/selftests/timers/posix_timers.c
@@ -495,6 +495,40 @@ static void check_sigev_none(int which)
 			 "check_sigev_none %s\n", name);
 }
 
+static void check_sigev_none_disarm(int which)
+{
+	const char *name = clock_name(which);
+	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()");
+
+	/* Arm the timer to expire in 100 seconds and disarm it again */
+	memset(&its, 0, sizeof(its));
+	its.it_value.tv_sec = 100;
+	if (timer_settime(timerid, 0, &its, NULL))
+		fatal_error(name, "timer_settime()");
+
+	memset(&its, 0, sizeof(its));
+	if (timer_settime(timerid, 0, &its, NULL))
+		fatal_error(name, "timer_settime()");
+
+	/* A disarmed timer must report a zero it_value */
+	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_disarm %s\n", name);
+}
+
 static void check_gettime(int which)
 {
 	const char *name = clock_name(which);
@@ -680,7 +714,7 @@ int main(int argc, char **argv)
 
 	ksft_print_header();
 	if (run_sig_ign_tests) {
-		ksft_set_plan(19);
+		ksft_set_plan(21);
 	} else {
 		ksft_set_plan(10);
 	}
@@ -714,6 +748,8 @@ int main(int argc, char **argv)
 		check_delete();
 		check_sigev_none(CLOCK_MONOTONIC);
 		check_sigev_none(CLOCK_PROCESS_CPUTIME_ID);
+		check_sigev_none_disarm(CLOCK_MONOTONIC);
+		check_sigev_none_disarm(CLOCK_PROCESS_CPUTIME_ID);
 		check_gettime(CLOCK_MONOTONIC);
 		check_gettime(CLOCK_PROCESS_CPUTIME_ID);
 		check_gettime(CLOCK_THREAD_CPUTIME_ID);
-- 
2.43.0