[PATCH stable backport] clockevents: Add missing resets of the next_event_forced flag

Thomas Gleixner
2026-04-21T06:26:23Z

commit 4096fd0e8eaea13ebe5206700b33f49635ae18e5 upstream.

The prevention mechanism against timer interrupt starvation missed to reset
the next_event_forced flag in a couple of places:

- When the clock event state changes. That can cause the flag to be
stale over a shutdown/startup sequence

- When a non-forced event is armed, which then prevents rearming before
that event. If that event is far out in the future this will cause
missed timer interrupts.

- In the suspend wakeup handler.

That led to stalls which have been reported by several people.

Add the missing resets, which fixes the problems for the reporters.

Fixes: d6e152d905bd ("clockevents: Prevent timer interrupt starvation")
Reported-by: Hanabishi <i.r.e.c.c.a.k.u.n+kernel.org@gmail.com>
Reported-by: Eric Naim <dnaim@cachyos.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Tested-by: Hanabishi <i.r.e.c.c.a.k.u.n+kernel.org@gmail.com>
Tested-by: Eric Naim <dnaim@cachyos.org>
Cc: stable@vger.kernel.org
Closes: https://lore.kernel.org/68d1e9ac-2780-4be3-8ee3-0788062dd3a4@gmail.com
Link: https://patch.msgid.link/87340xfeje.ffs@tglx

---
kernel/time/clockevents.c | 7 ++++++-
kernel/time/tick-broadcast.c | 1 +
2 files changed, 7 insertions(+), 1 deletion(-)

--- a/kernel/time/clockevents.c
+++ b/kernel/time/clockevents.c
@@ -94,6 +94,9 @@ static int __clockevents_switch_state(st
if (dev->features & CLOCK_EVT_FEAT_DUMMY)
return 0;

+ /* On state transitions clear the forced flag unconditionally */
+ dev->next_event_forced = 0;
+
/* Transition with new state-specific callbacks */
switch (state) {
case CLOCK_EVT_STATE_DETACHED:
@@ -332,8 +335,10 @@ int clockevents_program_event(struct clo
if (delta > (int64_t)dev->min_delta_ns) {
delta = min(delta, (int64_t) dev->max_delta_ns);
clc = ((unsigned long long) delta * dev->mult) >> dev->shift;
- if (!dev->set_next_event((unsigned long) clc, dev))
+ if (!dev->set_next_event((unsigned long) clc, dev)) {
+ dev->next_event_forced = 0;
return 0;
+ }
}

if (dev->next_event_forced)
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -108,6 +108,7 @@ static struct clock_event_device *tick_g

static void tick_oneshot_wakeup_handler(struct clock_event_device *wd)
{
+ wd->next_event_forced = 0;
/*
* If we woke up early and the tick was reprogrammed in the
* meantime then this may be spurious but harmless.