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The idle path reads and clears it via tick_nohz_idle_got_tick() to detect whether the tick handler has run. The flag is accessed locklessly from hardirq and task context. A concurrent set can be overwritten by the clear. Use READ_ONCE() and WRITE_ONCE() to annotate the lockless accesses. Signed-off-by: Kunwu Chan --- kernel/time/tick-sched.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 6c3fea386713..c0ab32e543b3 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -269,7 +269,7 @@ static void tick_sched_do_timer(struct tick_sched *ts, ktime_t now) } if (tick_sched_flag_test(ts, TS_FLAG_INIDLE)) - ts->got_idle_tick = 1; + WRITE_ONCE(ts->got_idle_tick, 1); } static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) @@ -1248,8 +1248,8 @@ bool tick_nohz_idle_got_tick(void) { struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); - if (ts->got_idle_tick) { - ts->got_idle_tick = 0; + if (READ_ONCE(ts->got_idle_tick)) { + WRITE_ONCE(ts->got_idle_tick, 0); return true; } return false; -- 2.43.0