linux-stable.git/kernel/time/hrtimer.c, branch linux-6.16.y

hrtimers: Unconditionally update target CPU base after offline timer migration

2025-09-19T14:37:34+00:00

commit e895f8e29119c8c966ea794af9e9100b10becb88 upstream.

When testing softirq based hrtimers on an ARM32 board, with high resolution
mode and NOHZ inactive, softirq based hrtimers fail to expire after being
moved away from an offline CPU:

CPU0				CPU1
				hrtimer_start(..., HRTIMER_MODE_SOFT);
cpu_down(CPU1)			...
				hrtimers_cpu_dying()
				  // Migrate timers to CPU0
				  smp_call_function_single(CPU0, returgger_next_event);
  retrigger_next_event()
    if (!highres && !nohz)
        return;

As retrigger_next_event() is a NOOP when both high resolution timers and
NOHZ are inactive CPU0's hrtimer_cpu_base::softirq_expires_next is not
updated and the migrated softirq timers never expire unless there is a
softirq based hrtimer queued on CPU0 later.

Fix this by removing the hrtimer_hres_active() and tick_nohz_active() check
in retrigger_next_event(), which enforces a full update of the CPU base.
As this is not a fast path the extra cost does not matter.

[ tglx: Massaged change log ]

Fixes: 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier")
Co-developed-by: Frederic Weisbecker 
Signed-off-by: Frederic Weisbecker 
Signed-off-by: Xiongfeng Wang 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/all/20250805081025.54235-1-wangxiongfeng2@huawei.com
Signed-off-by: Greg Kroah-Hartman

hrtimer: Add missing ACCESS_PRIVATE() for hrtimer::function

2025-04-09T19:00:42+00:00

The "function" field of struct hrtimer has been changed to private, but
two instances have not been converted to use ACCESS_PRIVATE().

Convert them to use ACCESS_PRIVATE().

Fixes: 04257da0c99c ("hrtimers: Make callback function pointer private")
Reported-by: kernel test robot 
Signed-off-by: Nam Cao 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/all/20250408103854.1851093-1-namcao@linutronix.de
Closes: https://lore.kernel.org/oe-kbuild-all/202504071931.vOVl13tt-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202504072155.5UAZjYGU-lkp@intel.com/

tracing/timers: Rename the hrtimer_init event to hrtimer_setup

2025-04-05T08:30:17+00:00

The function hrtimer_init() doesn't exist anymore. It was replaced by
hrtimer_setup().

Thus, rename the hrtimer_init trace event to hrtimer_setup to keep it
consistent.

Signed-off-by: Nam Cao 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar 
Link: https://lore.kernel.org/all/cba84c3d853c5258aa3a262363a6eac08e2c7afc.1738746927.git.namcao@linutronix.de

hrtimers: Rename debug_init_on_stack() to debug_setup_on_stack()

2025-04-05T08:30:17+00:00

All the hrtimer_init*() functions have been renamed to hrtimer_setup*().
Rename debug_init_on_stack() to debug_setup_on_stack() as well, to keep the
names consistent.

Signed-off-by: Nam Cao 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar 
Link: https://lore.kernel.org/all/073cf6162779a2f5b12624677d4c49ee7eccc1ed.1738746927.git.namcao@linutronix.de

hrtimers: Rename debug_init() to debug_setup()

2025-04-05T08:30:17+00:00

All the hrtimer_init*() functions have been renamed to hrtimer_setup*().
Rename debug_init() to debug_setup() as well, to keep the names consistent.

Signed-off-by: Nam Cao 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar 
Link: https://lore.kernel.org/all/4b730c1f79648b16a1c5413f928fdc2e138dfc43.1738746927.git.namcao@linutronix.de

hrtimers: Rename __hrtimer_init_sleeper() to __hrtimer_setup_sleeper()

2025-04-05T08:30:17+00:00

All the hrtimer_init*() functions have been renamed to hrtimer_setup*().
Rename __hrtimer_init_sleeper() to __hrtimer_setup_sleeper() as well, to
keep the names consistent.

Signed-off-by: Nam Cao 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar 
Link: https://lore.kernel.org/all/807694aedad9353421c4a7347629a30c5c31026f.1738746927.git.namcao@linutronix.de

hrtimers: Remove unnecessary NULL check in hrtimer_start_range_ns()

2025-04-05T08:30:17+00:00

The struct hrtimer::function field can only be changed using
hrtimer_setup*() or hrtimer_update_function(), and both already null-check
'function'. Therefore, null-checking 'function' in hrtimer_start_range_ns()
is not necessary.

Signed-off-by: Nam Cao 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar 
Link: https://lore.kernel.org/all/4661c571ee87980c340ccc318fc1a473c0c8f6bc.1738746927.git.namcao@linutronix.de

hrtimers: Make callback function pointer private

2025-04-05T08:30:17+00:00

Make the struct hrtimer::function field private, to prevent users from
changing this field in an unsafe way. hrtimer_update_function() should be
used if the callback function needs to be changed.

Signed-off-by: Nam Cao 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar 
Link: https://lore.kernel.org/all/7d0e6e0c5c59a64a9bea940051aac05d750bc0c2.1738746927.git.namcao@linutronix.de

hrtimers: Merge __hrtimer_init() into __hrtimer_setup()

2025-04-05T08:30:17+00:00

__hrtimer_init() is only called by __hrtimer_setup(). Simplify by merging
__hrtimer_init() into __hrtimer_setup().

Signed-off-by: Nam Cao 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar 
Link: https://lore.kernel.org/all/8a0a847a35f711f66b2d05b57255aa44e7e61279.1738746927.git.namcao@linutronix.de

hrtimers: Switch to use __htimer_setup()

2025-04-05T08:30:17+00:00

__hrtimer_init_sleeper() calls __hrtimer_init() and also sets up the
callback function. But there is already __hrtimer_setup() which does both
actions.

Switch to use __hrtimer_setup() to simplify the code.

Signed-off-by: Nam Cao 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Ingo Molnar 
Link: https://lore.kernel.org/all/d9a45a51b6a8aa0045310d63f73753bf6b33f385.1738746927.git.namcao@linutronix.de