linux-kernel - [RFC 09/60] sched: Do not require a CFS in init_tg_cfs

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Message-Id: <20180907214047.26914-10-jschoenh@amazon.de>
Date:   Fri,  7 Sep 2018 23:39:56 +0200
From:   Jan H. Schönherr <jschoenh@...zon.de>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Jan H. Schönherr <jschoenh@...zon.de>,
        linux-kernel@...r.kernel.org
Subject: [RFC 09/60] sched: Do not require a CFS in init_tg_cfs_entry()

Just like init_tg_cfs_entry() does something useful without a scheduling
entity, let it do something useful without a CFS runqueue.

This prepares for the addition of new types of SEs.

Signed-off-by: Jan H. Schönherr <jschoenh@...zon.de>
---
 kernel/sched/fair.c | 28 +++++++++++++++-------------
 1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2b3fd7cd9fde..bccd7a66858e 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9903,21 +9903,23 @@ void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
 		       struct sched_entity *se, struct rq *rq,
 		       struct cfs_rq *parent)
 {
-	cfs_rq->tg = tg;
-	cfs_rq->rq = rq;
-	cfs_rq->my_se = se;
-	init_cfs_rq_runtime(cfs_rq);
-
-	/* se could be NULL for root_task_group */
-	if (!se)
-		return;
+	/* cfs_rq may be NULL for certain types of SE */
+	if (cfs_rq) {
+		cfs_rq->tg = tg;
+		cfs_rq->rq = rq;
+		cfs_rq->my_se = se;
+		init_cfs_rq_runtime(cfs_rq);
+	}
 
-	set_entity_cfs(se, parent);
-	se->my_q = cfs_rq;
+	/* se is NULL for root_task_group */
+	if (se) {
+		set_entity_cfs(se, parent);
+		se->my_q = cfs_rq;
 
-	/* guarantee group entities always have weight */
-	update_load_set(&se->load, NICE_0_LOAD);
-	init_entity_runnable_average(se);
+		/* guarantee group entities always have weight */
+		update_load_set(&se->load, NICE_0_LOAD);
+		init_entity_runnable_average(se);
+	}
 }
 
 static DEFINE_MUTEX(shares_mutex);
-- 
2.9.3.1.gcba166c.dirty