[PATCH RFCv2 8/9] kernel/sched: Add cpu_rq_is_locked()

[Gavin Shan]

This adds API cpu_rq_is_locked() to check if the CPU's runqueue has been
locked or not. It's used in the subsequent patch to determine the task
wakeup should be executed immediately or delayed.

Signed-off-by: Gavin Shan <gshan@xxxxxxxxxx>
---
 include/linux/sched.h | 1 +
 kernel/sched/core.c   | 8 ++++++++
 2 files changed, 9 insertions(+)

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 4418f5cb8324..e68882443da7 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1691,6 +1691,7 @@ extern struct task_struct *find_task_by_pid_ns(pid_t nr, struct pid_namespace *n
  */
 extern struct task_struct *find_get_task_by_vpid(pid_t nr);
 
+extern bool cpu_rq_is_locked(int cpu);
 extern int wake_up_state(struct task_struct *tsk, unsigned int state);
 extern int wake_up_process(struct task_struct *tsk);
 extern void wake_up_new_task(struct task_struct *tsk);
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 9a2fbf98fd6f..30f4a8845495 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -73,6 +73,14 @@ __read_mostly int scheduler_running;
  */
 int sysctl_sched_rt_runtime = 950000;
 
+bool cpu_rq_is_locked(int cpu)
+{
+	struct rq *rq = cpu_rq(cpu);
+
+	return raw_spin_is_locked(&rq->lock) ? true :  false;
+}
+EXPORT_SYMBOL_GPL(cpu_rq_is_locked);
+
 /*
  * __task_rq_lock - lock the rq @p resides on.
  */
-- 
2.23.0