Revert "sched/fair: Move unused stub functions to header"

Revert commit 7aa55f2a ("sched/fair: Move unused stub functions to
header"), for while it has the right Changelog, the actual patch
content a revert of the previous 4 patches:

  f7df852a ("sched: Make task_vruntime_update() prototype visible")
  c0bdfd72 ("sched/fair: Hide unused init_cfs_bandwidth() stub")
  378be384 ("sched: Add schedule_user() declaration")
  d55ebae3 ("sched: Hide unused sched_update_scaling()")

So in effect this is a revert of a revert and re-applies those
patches.

Fixes: 7aa55f2a ("sched/fair: Move unused stub functions to header")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>

kernel/sched/fair.c

@@ -684,7 +684,7 @@ struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
 /**************************************************************
  * Scheduling class statistics methods:
  */
-
+#ifdef CONFIG_SMP
 int sched_update_scaling(void)
 {
 	unsigned int factor = get_update_sysctl_factor();
@@ -702,6 +702,7 @@ int sched_update_scaling(void)
 	return 0;
 }
 #endif
+#endif
 
 /*
  * delta /= w
@@ -6186,9 +6187,8 @@ static inline int throttled_lb_pair(struct task_group *tg,
 	return 0;
 }
 
-void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
-
 #ifdef CONFIG_FAIR_GROUP_SCHED
+void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
 static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
 #endif
 

kernel/sched/sched.h

@@ -1245,6 +1245,7 @@ static inline raw_spinlock_t *__rq_lockp(struct rq *rq)
 
 bool cfs_prio_less(const struct task_struct *a, const struct task_struct *b,
 			bool fi);
+void task_vruntime_update(struct rq *rq, struct task_struct *p, bool in_fi);
 
 /*
  * Helpers to check if the CPU's core cookie matches with the task's cookie
@@ -2398,6 +2399,7 @@ static inline struct cpuidle_state *idle_get_state(struct rq *rq)
 #endif
 
 extern void schedule_idle(void);
+asmlinkage void schedule_user(void);
 
 extern void sysrq_sched_debug_show(void);
 extern void sched_init_granularity(void);