linux/kernel/time
Xiongfeng Wang e895f8e291 hrtimers: Unconditionally update target CPU base after offline timer migration
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: 5c0930ccaa ("hrtimers: Push pending hrtimers away from outgoing CPU earlier")
Co-developed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Xiongfeng Wang <wangxiongfeng2@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250805081025.54235-1-wangxiongfeng2@huawei.com
2025-09-09 14:05:16 +02:00
..
alarmtimer.c alarmtimer: Switch spin_{lock,unlock}_irqsave() to guards 2025-04-30 09:06:23 +02:00
clockevents.c clockevents: Shutdown and unregister current clockevents at CPUHP_AP_TICK_DYING 2024-10-31 10:41:42 +01:00
clocksource-wdtest.c clocksource/wdtest: Print time values for short udelay(1) 2025-01-15 19:49:13 +01:00
clocksource.c bitmap-for-6.17 2025-07-31 16:52:32 -07:00
hrtimer.c hrtimers: Unconditionally update target CPU base after offline timer migration 2025-09-09 14:05:16 +02:00
itimer.c signal: Confine POSIX_TIMERS properly 2024-10-29 11:43:18 +01:00
jiffies.c time/jiffies: Change register_refined_jiffies() to void __init 2025-04-30 09:06:23 +02:00
Kconfig time: Introduce auxiliary POSIX clocks 2025-06-19 14:28:22 +02:00
Makefile tracing: Disable branch profiling in noinstr code 2025-03-22 09:49:26 +01:00
namespace.c vdso/vsyscall: Update auxiliary clock data in the datapage 2025-07-18 13:45:33 +02:00
ntp.c ntp: Use ktime_get_ntp_seconds() 2025-06-19 14:28:24 +02:00
ntp_internal.h ntp: Rename __do_adjtimex() to ntp_adjtimex() 2025-06-19 14:28:23 +02:00
posix-clock.c Networking changes for 6.15. 2025-03-26 21:48:21 -07:00
posix-cpu-timers.c posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del() 2025-06-13 10:55:49 -07:00
posix-stubs.c
posix-timers.c timekeeping: Add minimal posix-timers support for auxiliary clocks 2025-06-27 20:13:12 +02:00
posix-timers.h timekeeping: Add minimal posix-timers support for auxiliary clocks 2025-06-27 20:13:12 +02:00
sched_clock.c time: Switch to hrtimer_setup() 2025-02-18 10:32:33 +01:00
sleep_timeout.c treewide, timers: Rename from_timer() to timer_container_of() 2025-06-08 09:07:37 +02:00
test_udelay.c
tick-broadcast-hrtimer.c time: Switch to hrtimer_setup() 2025-02-18 10:32:33 +01:00
tick-broadcast.c tick/broadcast: Add kernel-doc for function parameters 2025-01-15 19:49:14 +01:00
tick-common.c timekeeping: Add a lockdep override in tick_freeze() 2025-04-09 22:30:39 +02:00
tick-internal.h clockevents: Shutdown and unregister current clockevents at CPUHP_AP_TICK_DYING 2024-10-31 10:41:42 +01:00
tick-legacy.c
tick-oneshot.c
tick-sched.c time: Switch to hrtimer_setup() 2025-02-18 10:32:33 +01:00
tick-sched.h
time.c time: Fix references to _msecs_to_jiffies() handling of values 2024-10-25 19:50:10 +02:00
time_test.c
timeconst.bc
timeconv.c
timecounter.c time/timecounter: Fix the lie that struct cyclecounter is const 2025-07-01 15:38:25 +02:00
timekeeping.c vdso/vsyscall: Avoid slow division loop in auxiliary clock update 2025-09-03 11:55:11 +02:00
timekeeping.h
timekeeping_debug.c timekeeping: Add percpu counter for tracking floor swap events 2024-10-10 10:20:46 +02:00
timekeeping_internal.h timekeeping: Provide ktime_get_ntp_seconds() 2025-06-19 14:28:23 +02:00
timer.c Updates for the time/timer core code: 2025-05-27 09:04:15 -07:00
timer_list.c hrtimers: Make callback function pointer private 2025-04-05 10:30:17 +02:00
timer_migration.c timers/migration: Clean up the loop in tmigr_quick_check() 2025-06-12 21:03:45 +02:00
timer_migration.h timer/migration: Fix kernel-doc warnings for union tmigr_state 2025-01-15 19:49:14 +01:00
vsyscall.c vdso/vsyscall: Avoid slow division loop in auxiliary clock update 2025-09-03 11:55:11 +02:00