VisionFive2 Linux kernel

StarFive Tech Linux Kernel for VisionFive (JH7110) boards (mirror)

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author: Rik van Riel <riel@surriel.com> 2021-06-21 19:43:30 +0200 committer: Ingo Molnar <mingo@kernel.org> 2021-06-22 14:06:57 +0200 commit: fdaba61ef8a268d4136d0a113d153f7a89eb9984 parent: a96bfed64c8986d6404e553f18203cae1f5ac7e6
Commit Summary:
sched/fair: Ensure that the CFS parent is added after unthrottling
Diffstat:
1 file changed, 24 insertions, 0 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index bfaa6e1f6067..23663318fb81 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3298,6 +3298,31 @@ static inline void cfs_rq_util_change(struct cfs_rq *cfs_rq, int flags)
 
 #ifdef CONFIG_SMP
 #ifdef CONFIG_FAIR_GROUP_SCHED
+/*
+ * Because list_add_leaf_cfs_rq always places a child cfs_rq on the list
+ * immediately before a parent cfs_rq, and cfs_rqs are removed from the list
+ * bottom-up, we only have to test whether the cfs_rq before us on the list
+ * is our child.
+ * If cfs_rq is not on the list, test whether a child needs its to be added to
+ * connect a branch to the tree  * (see list_add_leaf_cfs_rq() for details).
+ */
+static inline bool child_cfs_rq_on_list(struct cfs_rq *cfs_rq)
+{
+	struct cfs_rq *prev_cfs_rq;
+	struct list_head *prev;
+
+	if (cfs_rq->on_list) {
+		prev = cfs_rq->leaf_cfs_rq_list.prev;
+	} else {
+		struct rq *rq = rq_of(cfs_rq);
+
+		prev = rq->tmp_alone_branch;
+	}
+
+	prev_cfs_rq = container_of(prev, struct cfs_rq, leaf_cfs_rq_list);
+
+	return (prev_cfs_rq->tg->parent == cfs_rq->tg);
+}
 
 static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
 {
@@ -3313,6 +3338,9 @@ static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
 	if (cfs_rq->avg.runnable_sum)
 		return false;
 
+	if (child_cfs_rq_on_list(cfs_rq))
+		return false;
+
 	return true;
 }