[RFC PATCH 12/18] tick/nohz: Introduce tick_nohz_full_update_cpus() to update tick_nohz_full_mask

[Waiman Long <longman@redhat.com>]

When the list of HK_FLAG_KERNEL_NOISE housekeeping CPUs are changed,
we will need to update tick_nohz_full_mask so that dynticks can work
correctly. Introduce a new tick_nohz_full_update_cpus() function
that can be called at run time to update tick_nohz_full_mask.

Signed-off-by: Waiman Long <longman@redhat.com>
---
 include/linux/tick.h     | 2 ++
 kernel/time/tick-sched.c | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/include/linux/tick.h b/include/linux/tick.h
index ac76ae9fa36d..34907c0b632c 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -272,6 +272,7 @@ static inline void tick_dep_clear_signal(struct signal_struct *signal,
 extern void tick_nohz_full_kick_cpu(int cpu);
 extern void __tick_nohz_task_switch(void);
 extern void __init tick_nohz_full_setup(cpumask_var_t cpumask);
+extern void tick_nohz_full_update_cpus(cpumask_var_t cpumask);
 #else
 static inline bool tick_nohz_full_enabled(void) { return false; }
 static inline bool tick_nohz_full_cpu(int cpu) { return false; }
@@ -297,6 +298,7 @@ static inline void tick_dep_clear_signal(struct signal_struct *signal,
 static inline void tick_nohz_full_kick_cpu(int cpu) { }
 static inline void __tick_nohz_task_switch(void) { }
 static inline void tick_nohz_full_setup(cpumask_var_t cpumask) { }
+static inline void tick_nohz_full_update_cpus(cpumask_var_t cpumask) { return false; }
 #endif
 
 static inline void tick_nohz_task_switch(void)
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 87b26a4471e7..9204808b7a55 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -604,6 +604,12 @@ void __init tick_nohz_full_setup(cpumask_var_t cpumask)
 	tick_nohz_full_running = true;
 }
 
+/* Get the new set of run-time nohz CPU list from cpuset */
+void tick_nohz_full_update_cpus(cpumask_var_t cpumask)
+{
+	cpumask_copy(tick_nohz_full_mask, cpumask);
+}
+
 bool tick_nohz_cpu_hotpluggable(unsigned int cpu)
 {
 	/*
-- 
2.50.0