[PATCH] sched/fair: merge same code in enqueue_task_fair

[WangJinchao]

1. The code below is duplicated in two for loops and need to be
   consolidated
2. Fix the bug where a se's on_rq is true but its parent is not

```c
		cfs_rq->h_nr_running++;
		cfs_rq->idle_h_nr_running += idle_h_nr_running;

		if (cfs_rq_is_idle(cfs_rq))
			idle_h_nr_running = 1;

		/* end evaluation on encountering a throttled cfs_rq */
		if (cfs_rq_throttled(cfs_rq))
			goto enqueue_throttle;
```

Signed-off-by: WangJinchao <wangjinchao@xxxxxxxxxxx>
---
 kernel/sched/fair.c | 31 ++++++++-----------------------
 1 file changed, 8 insertions(+), 23 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index d7a3c63a2171..e1373bfd4f2e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6681,30 +6681,15 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
 		cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT);
 
 	for_each_sched_entity(se) {
-		if (se->on_rq)
-			break;
 		cfs_rq = cfs_rq_of(se);
-		enqueue_entity(cfs_rq, se, flags);
-
-		cfs_rq->h_nr_running++;
-		cfs_rq->idle_h_nr_running += idle_h_nr_running;
-
-		if (cfs_rq_is_idle(cfs_rq))
-			idle_h_nr_running = 1;
-
-		/* end evaluation on encountering a throttled cfs_rq */
-		if (cfs_rq_throttled(cfs_rq))
-			goto enqueue_throttle;
-
-		flags = ENQUEUE_WAKEUP;
-	}
-
-	for_each_sched_entity(se) {
-		cfs_rq = cfs_rq_of(se);
-
-		update_load_avg(cfs_rq, se, UPDATE_TG);
-		se_update_runnable(se);
-		update_cfs_group(se);
+		if (se->on_rq) {
+			update_load_avg(cfs_rq, se, UPDATE_TG);
+			se_update_runnable(se);
+			update_cfs_group(se);
+		} else {
+			enqueue_entity(cfs_rq, se, flags);
+			flags = ENQUEUE_WAKEUP;
+		}
 
 		cfs_rq->h_nr_running++;
 		cfs_rq->idle_h_nr_running += idle_h_nr_running;
-- 
2.40.0