linux-stable.git/kernel/time/alarmtimer.c, branch v7.1.5

posix-timers: Expand timer_[re]arm() callbacks with a boolean return value

2026-07-24T14:21:26+00:00

commit 6fdb2677a594ab38eade927919bbd4d9688bfa1c upstream.

In order to catch expiry times which are already in the past the
timer_arm() and timer_rearm() callbacks need to be able to report back to
the caller whether the timer has been queued or not.

Change the function signature and let all implementations return true for
now. While at it simplify posix_cpu_timer_rearm().

No functional change intended.

Signed-off-by: Thomas Gleixner 
Reviewed-by: Frederic Weisbecker 
Acked-by: Peter Zijlstra (Intel) 
Acked-by: John Stultz 
Link: https://patch.msgid.link/20260408114952.130222296@kernel.org
Signed-off-by: Salvatore Bonaccorso 
Signed-off-by: Greg Kroah-Hartman

alarmtimer: Remove stale return description from alarm_handle_timer()

2026-07-24T14:19:09+00:00

[ Upstream commit ed3b3c4976686b63b28e44f9805a88abc20ff18a ]

alarm_handle_timer() was converted from returning enum alarmtimer_restart
to void, but the kernel-doc "Return:" line was not removed. Remove the
stale description.

Fixes: 2634303f8773 ("alarmtimers: Remove return value from alarm functions")
Signed-off-by: Zhan Xusheng 
Signed-off-by: Thomas Gleixner 
Link: https://patch.msgid.link/20260429080635.166790-1-zhanxusheng@xiaomi.com
Signed-off-by: Sasha Levin

Merge branch 'timers/urgent' into timers/core

2026-04-11T05:58:33+00:00

to resolve the conflict with urgent fixes.

alarmtimer: Access timerqueue node under lock in suspend

2026-04-07T17:14:26+00:00

In alarmtimer_suspend(), timerqueue_getnext() is called under
base->lock, but next->expires is read after the lock is released.

This is safe because suspend freezes all relevant task contexts,
but reading the node while holding the lock makes the code easier
to reason about and not worry about a theoretical UAF.

Signed-off-by: Zhan Xusheng 
Signed-off-by: Thomas Gleixner 
Link: https://patch.msgid.link/20260407143627.19405-1-zhanxusheng@xiaomi.com

alarmtimer: Fix argument order in alarm_timer_forward()

2026-03-24T22:17:14+00:00

alarm_timer_forward() passes arguments to alarm_forward() in the wrong
order:

  alarm_forward(alarm, timr->it_interval, now);

However, alarm_forward() is defined as:

  u64 alarm_forward(struct alarm *alarm, ktime_t now, ktime_t interval);

and uses the second argument as the current time:

  delta = ktime_sub(now, alarm->node.expires);

Passing the interval as "now" results in incorrect delta computation,
which can lead to missed expirations or incorrect overrun accounting.

This issue has been present since the introduction of
alarm_timer_forward().

Fix this by swapping the arguments.

Fixes: e7561f1633ac ("alarmtimer: Implement forward callback")
Signed-off-by: Zhan Xusheng 
Signed-off-by: Thomas Gleixner 
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260323061130.29991-1-zhanxusheng@xiaomi.com

time: Fix spelling mistakes in comments

2025-09-21T08:02:02+00:00

Correct several typos found in comments across various files in the
kernel/time directory.

No functional changes are introduced by these corrections.

Signed-off-by: Haofeng Li 
Signed-off-by: Thomas Gleixner

alarmtimer: Switch spin_{lock,unlock}_irqsave() to guards

2025-04-30T07:06:23+00:00

Using guard/scoped_guard() to simplify code. Using guard() to remove
'goto unlock' label is neater especially.

[ tglx: Brought back the scoped_guard()'s which were dropped in v2 and
  	simplified alarmtimer_rtc_add_device() ]

Signed-off-by: Su Hui 
Signed-off-by: Thomas Gleixner 
Acked-by: John Stultz 
Link: https://lore.kernel.org/all/20250430032734.2079290-4-suhui@nfschina.com

alarmtimer: Remove dead return value in clock2alarm()

2025-04-30T07:06:23+00:00

'clockid' can only be ALARM_REALTIME and ALARM_BOOTTIME. It's impossible to
return -1 and callers never check the return value.

Only alarm_clock_get_timespec(), alarm_clock_get_ktime(),
alarm_timer_create() and alarm_timer_nsleep() call clock2alarm(). These
callers use clockid_to_kclock() to get 'struct k_clock', which ensures
that clock2alarm() never returns -1.

Remove the impossible -1 return value, and add a warning to notify about any
future misuse of this function.

Signed-off-by: Su Hui 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/all/20250430032734.2079290-3-suhui@nfschina.com

alarmtimer: Switch to use hrtimer_setup() and hrtimer_setup_on_stack()

2024-11-07T01:47:07+00:00

hrtimer_setup() and hrtimer_setup_on_stack() take the callback function
pointer as argument and initialize the timer completely.

Replace the hrtimer_init*() variants and the open coded initialization of
hrtimer::function with the new setup mechanism.

Switch to use the new functions.

Signed-off-by: Nam Cao 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/all/2bae912336103405adcdab96b88d3ea0353b4228.1730386209.git.namcao@linutronix.de

alarmtimers: Remove return value from alarm functions

2024-11-07T01:14:46+00:00

Now that the SIG_IGN problem is solved in the core code, the alarmtimer
callbacks do not require a return value anymore.

Signed-off-by: Thomas Gleixner 
Acked-by: Peter Zijlstra (Intel) 
Acked-by: Frederic Weisbecker 
Link: https://lore.kernel.org/all/20241105064214.318837272@linutronix.de