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

[Waiman Long]

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@xxxxxxxxxx>
---
 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