[patch V2 07/11] alarmtimer: Convert posix timer functions to alarm_start_timer()

Thomas Gleixner
2026-04-08T11:54:18Z

Use the new alarm_start_timer() for arming and rearming posix interval
timers and for clock_nanosleep() so that already expired timers do not go
through the full timer interrupt cycle.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: John Stultz <jstultz@google.com>
Cc: Stephen Boyd <sboyd@kernel.org>
---
V2: Rename to alarm_start_timer()
---
kernel/time/alarmtimer.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -560,8 +560,7 @@ static bool alarm_timer_rearm(struct k_i
struct alarm *alarm = &timr->it.alarm.alarmtimer;

timr->it_overrun += alarm_forward_now(alarm, timr->it_interval);
- alarm_start(alarm, alarm->node.expires);
- return true;
+ return alarm_start_timer(alarm, alarm->node.expires, false);
}

/**
@@ -625,11 +624,16 @@ static bool alarm_timer_arm(struct k_iti

if (!absolute)
expires = ktime_add_safe(expires, base->get_ktime());
- if (sigev_none)
+
+ /*
+ * sigev_none needs to update the expires value and pretend
+ * that the timer is queued
+ */
+ if (sigev_none) {
alarm->node.expires = expires;
- else
- alarm_start(&timr->it.alarm.alarmtimer, expires);
- return true;
+ return true;
+ }
+ return alarm_start_timer(&timr->it.alarm.alarmtimer, expires, false);
}

/**
@@ -736,7 +740,9 @@ static int alarmtimer_do_nsleep(struct a
alarm->data = (void *)current;
do {
set_current_state(TASK_INTERRUPTIBLE);
- alarm_start(alarm, absexp);
+ if (!alarm_start_timer(alarm, absexp, false))
+ alarm->data = NULL;
+
if (likely(alarm->data))
schedule();