linux-yocto/kernel/time
Xiongfeng Wang 51d7f652b3 hrtimers: Unconditionally update target CPU base after offline timer migration
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: 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
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2025-09-19 16:35:47 +02:00
..
alarmtimer.c treewide: Fix wrong singular form of jiffies in comments 2024-09-08 20:47:40 +02:00
clockevents.c treewide: Fix wrong singular form of jiffies in comments 2024-09-08 20:47:40 +02:00
clocksource-wdtest.c
clocksource.c clocksource: Fix the CPUs' choice in the watchdog per CPU verification 2025-06-27 11:11:26 +01:00
hrtimer.c hrtimers: Unconditionally update target CPU base after offline timer migration 2025-09-19 16:35:47 +02:00
itimer.c
jiffies.c
Kconfig timekeeping: Always check for negative motion 2024-12-14 20:03:38 +01:00
Makefile
namespace.c
ntp_internal.h ntp: Make sure RTC is synchronized when time goes backwards 2024-09-10 13:50:40 +02:00
ntp.c ntp: Remove invalid cast in time offset math 2024-12-14 20:03:12 +01:00
posix-clock.c posix-clock: posix-clock: Fix unbalanced locking in pc_clock_settime() 2024-10-23 16:05:01 +02:00
posix-cpu-timers.c posix-cpu-timers: fix race between handle_posix_cpu_timers() and posix_cpu_timer_del() 2025-06-19 15:32:34 +02:00
posix-stubs.c
posix-timers.c posix-timers: Ensure that timer initialization is fully visible 2025-05-29 11:02:20 +02:00
posix-timers.h
sched_clock.c
test_udelay.c
tick-broadcast-hrtimer.c
tick-broadcast.c
tick-common.c timekeeping: Add a lockdep override in tick_freeze() 2025-05-02 07:59:25 +02:00
tick-internal.h
tick-legacy.c
tick-oneshot.c
tick-sched.c sched/fair: Fix external p->on_rq users 2024-10-14 09:14:35 +02:00
tick-sched.h
time_test.c
time.c time: Fix references to _msecs_to_jiffies() handling of values 2024-12-05 14:01:22 +01:00
timeconst.bc
timeconv.c
timecounter.c
timekeeping_debug.c
timekeeping_internal.h clocksource: Make negative motion detection more robust 2024-12-14 20:04:16 +01:00
timekeeping.c timekeeping: Zero initialize system_counterval when querying time from phc drivers 2025-08-01 09:48:42 +01:00
timekeeping.h
timer_list.c timer_list: Don't use %pK through printk() 2025-05-29 11:02:20 +02:00
timer_migration.c timers/migration: Fix off-by-one root mis-connection 2025-02-17 10:05:44 +01:00
timer_migration.h
timer.c timers: Add missing READ_ONCE() in __run_timer_base() 2024-12-05 14:01:22 +01:00
vsyscall.c