linux/kernel/time
Thomas Gleixner f87cbcb345 timekeeping: Use READ/WRITE_ONCE() for tick_do_timer_cpu
tick_do_timer_cpu is used lockless to check which CPU needs to take care
of the per tick timekeeping duty. This is done to avoid a thundering
herd problem on jiffies_lock.

The read and writes are not annotated so KCSAN complains about data races:

  BUG: KCSAN: data-race in tick_nohz_idle_stop_tick / tick_nohz_next_event

  write to 0xffffffff8a2bda30 of 4 bytes by task 0 on cpu 26:
   tick_nohz_idle_stop_tick+0x3b1/0x4a0
   do_idle+0x1e3/0x250

  read to 0xffffffff8a2bda30 of 4 bytes by task 0 on cpu 16:
   tick_nohz_next_event+0xe7/0x1e0
   tick_nohz_get_sleep_length+0xa7/0xe0
   menu_select+0x82/0xb90
   cpuidle_select+0x44/0x60
   do_idle+0x1c2/0x250

  value changed: 0x0000001a -> 0xffffffff

Annotate them with READ/WRITE_ONCE() to document the intentional data race.

Reported-by: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sean Anderson <sean.anderson@seco.com>
Link: https://lore.kernel.org/r/87cyqy7rt3.ffs@tglx
2024-04-10 10:13:42 +02:00
..
alarmtimer.c rtc: class: make rtc_class constant 2024-03-08 12:05:10 +01:00
clockevents.c clockevents: Make clockevents_subsys const 2024-02-07 15:11:24 +01:00
clocksource-wdtest.c clocksource: Scale the watchdog read retries automatically 2024-02-21 12:00:42 +01:00
clocksource.c clocksource: Scale the watchdog read retries automatically 2024-02-21 12:00:42 +01:00
hrtimer.c tick: Split nohz and highres features from nohz_mode 2024-02-26 11:37:32 +01:00
itimer.c time: Prevent undefined behaviour in timespec64_to_ns() 2020-10-26 11:48:11 +01:00
jiffies.c clocksource: Make clocksource watchdog test safe for slow-HZ systems 2021-08-28 17:01:32 +02:00
Kconfig sched/idle: Conditionally handle tick broadcast in default_idle_call() 2024-03-01 21:04:27 +01:00
Makefile timers: Implement the hierarchical pull model 2024-02-22 17:52:32 +01:00
namespace.c vdso/timens: Refactor copy-pasted find_timens_vvar_page() helper into one copy 2022-12-01 11:35:40 +01:00
ntp_internal.h ntp: Make the RTC synchronization more reliable 2020-12-11 10:40:52 +01:00
ntp.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00
posix-clock.c Fix memory leak in posix_clock_open() 2024-03-27 09:03:22 -07:00
posix-cpu-timers.c posix-cpu-timers: Implement the missing timer_wait_running callback 2023-04-21 15:34:33 +02:00
posix-stubs.c posix-timers: Get rid of [COMPAT_]SYS_NI() uses 2023-12-20 21:30:27 -08:00
posix-timers.c posix-timers: Refer properly to CONFIG_HIGH_RES_TIMERS 2023-06-18 22:41:53 +02:00
posix-timers.h posix-clocks: Introduce clock_get_ktime() callback 2020-01-14 12:20:51 +01:00
sched_clock.c time/sched_clock: Provide sched_clock_noinstr() 2023-06-05 21:11:04 +02:00
test_udelay.c time/debug: Fix memory leak with using debugfs_lookup() 2023-02-09 20:12:27 +01:00
tick-broadcast-hrtimer.c time/tick-broadcast: Remove RCU_NONIDLE() usage 2023-01-13 11:48:16 +01:00
tick-broadcast.c tick/broadcast: Make broadcast device replacement work correctly 2023-05-08 23:18:16 +02:00
tick-common.c timekeeping: Use READ/WRITE_ONCE() for tick_do_timer_cpu 2024-04-10 10:13:42 +02:00
tick-internal.h tick: Move broadcast cancellation up to CPUHP_AP_TICK_DYING 2024-02-26 11:37:32 +01:00
tick-legacy.c timekeeping: remove xtime_update 2020-10-30 21:57:07 +01:00
tick-oneshot.c time: Fix various kernel-doc problems 2023-01-03 11:07:58 +01:00
tick-sched.c timekeeping: Use READ/WRITE_ONCE() for tick_do_timer_cpu 2024-04-10 10:13:42 +02:00
tick-sched.h tick/sched: Fix struct tick_sched doc warnings 2024-04-01 10:36:35 +02:00
time_test.c time: test: Fix incorrect format specifier 2024-02-27 15:26:08 -07:00
time.c time: add kernel-doc in time.c 2023-07-14 13:47:07 -06:00
timeconst.bc time: Add SPDX license identifiers 2018-11-23 11:51:20 +01:00
timeconv.c time: Improve performance of time64_to_tm() 2021-06-24 11:51:59 +02:00
timecounter.c time/timecounter: Mark 1st argument of timecounter_cyc2time() as const 2021-04-16 21:03:50 +02:00
timekeeping_debug.c timekeeping/debug: No need to check return value of debugfs_create functions 2019-01-29 20:08:41 +01:00
timekeeping_internal.h timekeeping/vsyscall: Provide vdso_update_begin/end() 2020-08-06 10:57:30 +02:00
timekeeping.c A large set of updates and features for timers and timekeeping: 2024-03-11 14:38:26 -07:00
timekeeping.h asm-generic: cross-architecture timer cleanup 2020-12-16 00:07:17 -08:00
timer_list.c tick: Split nohz and highres features from nohz_mode 2024-02-26 11:37:32 +01:00
timer_migration.c timers/migration: Return early on deactivation 2024-04-05 11:05:16 +02:00
timer_migration.h timers: Implement the hierarchical pull model 2024-02-22 17:52:32 +01:00
timer.c timers: Fix text inconsistencies and spelling 2024-04-01 10:36:35 +02:00
vsyscall.c timekeeping, clocksource: Fix various typos in comments 2021-03-22 23:06:48 +01:00