[RFC 32/60] cosched: Specialize parent_cfs_rq() for hierarchical runqueues

[Jan H. SchÃnherr]

Make parent_cfs_rq() coscheduling-aware.

Signed-off-by: Jan H. SchÃnherr <jschoenh@xxxxxxxxx>
---
 kernel/sched/fair.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 8504790944bf..8cba7b8fb6bd 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -284,12 +284,25 @@ static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
 	return grp->my_q;
 }
 
+#ifdef CONFIG_COSCHEDULING
+static inline struct cfs_rq *parent_cfs_rq(struct cfs_rq *cfs_rq)
+{
+	/*
+	 * Only return TG parent (if valid), don't switch levels.
+	 * Callers stay or expect to stay within the same level.
+	 */
+	if (!cfs_rq->sdrq.tg_parent || !cfs_rq->sdrq.is_root)
+		return NULL;
+	return cfs_rq->sdrq.tg_parent->cfs_rq;
+}
+#else /* !CONFIG_COSCHEDULING */
 static inline struct cfs_rq *parent_cfs_rq(struct cfs_rq *cfs_rq)
 {
 	if (!cfs_rq->tg->parent)
 		return NULL;
 	return cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))];
 }
+#endif /* !CONFIG_COSCHEDULING */
 
 static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
 {
-- 
2.9.3.1.gcba166c.dirty