[RFC PATCH v2 2/5] sched: Add group_se() helper

["Michal Koutný" <mkoutny@suse.com>]

No functional change, unify cfs_rq to sched_entity conversion (and move
closer to use where possible). The helper is used only by
CONFIG_FAIR_GROUP_SCHED code, i.e. no dummy variant is defined.

Signed-off-by: Michal Koutný <mkoutny@suse.com>
---
 kernel/sched/fair.c  | 9 +++------
 kernel/sched/sched.h | 8 ++++++++
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2c41a9007928..905f95b91a7a 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4824,8 +4824,6 @@ static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
 	if (!dequeue)
 		return false;  /* Throttle no longer required. */
 
-	se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
-
 	/* freeze hierarchy runnable averages while throttled */
 	rcu_read_lock();
 	walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
@@ -4833,6 +4831,7 @@ static bool throttle_cfs_rq(struct cfs_rq *cfs_rq)
 
 	task_delta = cfs_rq->h_nr_running;
 	idle_task_delta = cfs_rq->idle_h_nr_running;
+	se = group_se(cfs_rq);
 	for_each_sched_entity(se) {
 		struct cfs_rq *qcfs_rq = cfs_rq_of(se);
 		/* throttled entity or throttle-on-deactivate */
@@ -4884,8 +4883,6 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
 	struct sched_entity *se;
 	long task_delta, idle_task_delta;
 
-	se = cfs_rq->tg->se[cpu_of(rq)];
-
 	cfs_rq->throttled = 0;
 
 	update_rq_clock(rq);
@@ -4898,6 +4895,7 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
 	/* update hierarchical throttle state */
 	walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
 
+	se = group_se(cfs_rq);
 	if (!cfs_rq->load.weight) {
 		/* Nothing to run but something to decay? Complete the branch */
 		if (cfs_rq->on_list)
@@ -8163,8 +8161,7 @@ static bool __update_blocked_fair(struct rq *rq, bool *done)
  */
 static void update_cfs_rq_h_load(struct cfs_rq *cfs_rq)
 {
-	struct rq *rq = rq_of(cfs_rq);
-	struct sched_entity *se = cfs_rq->tg->se[cpu_of(rq)];
+	struct sched_entity *se = group_se(cfs_rq);
 	unsigned long now = jiffies;
 	unsigned long load;
 
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 14a41a243f7b..219ee463fe64 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1383,6 +1383,14 @@ static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
 	return grp->my_q;
 }
 
+/* sched entity representing the cfs_rq, NULL for root */
+static inline struct sched_entity *group_se(struct cfs_rq *cfs_rq)
+{
+	int cpu = cpu_of(rq_of(cfs_rq));
+
+	return cfs_rq->tg->se[cpu];
+}
+
 #else
 
 static inline struct task_struct *task_of(struct sched_entity *se)
-- 
2.32.0