ANDROID: sched: allow access to critical common code for CPU Pause

Allow module access to critical functionality to support
CPU Pause from a vendor module.

Bug: 205164003
Change-Id: Ia04608dae076469e265071f8e0d53aee66d49cfa
Signed-off-by: Stephen Dickey <quic_dickey@quicinc.com>

include/linux/sched.h

@@ -299,6 +299,7 @@ extern void io_schedule_finish(int token);
 extern long io_schedule_timeout(long timeout);
 extern void io_schedule(void);
 extern struct task_struct *pick_migrate_task(struct rq *rq);
+extern int select_fallback_rq(int cpu, struct task_struct *p);
 
 /**
  * struct prev_cputime - snapshot of system and user cputime

kernel/sched/core.c

@@ -2305,8 +2305,8 @@ struct set_affinity_pending {
  * So we race with normal scheduler movements, but that's OK, as long
  * as the task is no longer on this CPU.
  */
-static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf,
-				 struct task_struct *p, int dest_cpu)
+struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf,
+			  struct task_struct *p, int dest_cpu)
 {
 	/* Affinity changed (again). */
 	if (!is_cpu_allowed(p, dest_cpu))
@@ -2317,6 +2317,7 @@ static struct rq *__migrate_task(struct rq *rq, struct rq_flags *rf,
 
 	return rq;
 }
+EXPORT_SYMBOL_GPL(__migrate_task);
 
 /*
  * migration_cpu_stop - this will be executed by a highprio stopper thread
@@ -3350,7 +3351,7 @@ EXPORT_SYMBOL_GPL(kick_process);
  * select_task_rq() below may allow selection of !active CPUs in order
  * to satisfy the above rules.
  */
-static int select_fallback_rq(int cpu, struct task_struct *p)
+int select_fallback_rq(int cpu, struct task_struct *p)
 {
 	int nid = cpu_to_node(cpu);
 	const struct cpumask *nodemask = NULL;
@@ -3424,6 +3425,7 @@ out:
 
 	return dest_cpu;
 }
+EXPORT_SYMBOL_GPL(select_fallback_rq);
 
 /*
  * The caller (fork, wakeup) owns p->pi_lock, ->cpus_ptr is stable.

kernel/stop_machine.c

@@ -152,6 +152,7 @@ int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
 	wait_for_completion(&done.completion);
 	return done.ret;
 }
+EXPORT_SYMBOL_GPL(stop_one_cpu);
 
 /* This controls the threads on each CPU. */
 enum multi_stop_state {