[PATCH 11/23] hrtimer: Use RCU to protect access of HK_TYPE_TIMER cpumask

Waiman Long
2026-04-21T03:06:26Z

As HK_TYPE_TIMER cpumask is going to be changeable at run time, use
RCU to protect access to the cpumask.

The access of HK_TYPE_TIMER cpumask within hrtimers_cpu_dying() is
protected as interrupt is disabled and all the other CPUs are stopped
when this function is invoked as part of the CPU tear down process.

Signed-off-by: Waiman Long <longman@redhat.com>
---
kernel/time/hrtimer.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index 000fb6ba7d74..85495400a193 100644
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -242,8 +242,10 @@ static bool hrtimer_suitable_target(struct hrtimer *timer, struct hrtimer_clock_
static inline struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base, bool pinned)
{
if (!hrtimer_base_is_online(base)) {
- int cpu = cpumask_any_and(cpu_online_mask, housekeeping_cpumask(HK_TYPE_TIMER));
+ int cpu;

+ guard(rcu)();
+ cpu = cpumask_any_and(cpu_online_mask, housekeeping_cpumask(HK_TYPE_TIMER));
return &per_cpu(hrtimer_bases, cpu);
}

--
2.53.0