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hrtimer: Apply READ_ONCE() to lockless base->running loads

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Updates to base->running are protected by the hrtimer base lock, but some
loads are lockless.  Therefore, prevent compiler mischief by applying
READ_ONCE() to the lockless loads.

KCSAN located this issue.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260919001428.3133388-12-paulmck@kernel.org
This commit is contained in:
Paul E. McKenney 2026-09-18 17:14:28 -07:00 committed by Thomas Gleixner
parent ad80926d78
commit 5dffe33bfd
1 changed files with 3 additions and 3 deletions
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6
kernel/time/hrtimer.c
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@ -2004,7 +2004,7 @@ bool hrtimer_active(const struct hrtimer *timer)
base = READ_ONCE(timer->base);
seq = raw_read_seqcount_begin(&base->seq);
if (timer->is_queued || base->running == timer)
if (timer->is_queued || READ_ONCE(base->running) == timer)
return true;
} while (read_seqcount_retry(&base->seq, seq) || base != READ_ONCE(timer->base));
@ -2041,7 +2041,7 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base, struct hrtimer_cloc
lockdep_assert_held(&cpu_base->lock);
debug_hrtimer_deactivate(timer);
base->running = timer;
WRITE_ONCE(base->running, timer);
/*
* Separate the ->running assignment from the ->is_queued assignment.
@ -2100,7 +2100,7 @@ static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base, struct hrtimer_cloc
raw_write_seqcount_barrier(&base->seq);
WARN_ON_ONCE(base->running != timer);
base->running = NULL;
WRITE_ONCE(base->running, NULL);
}
static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,