[PATCH] sched/uclamp: Fix rq->uclamp_max not set on first enqueue

Qais Yousef
2021-11-25T16:54:53Z

Commit d81ae8aac85c ("sched/uclamp: Fix initialization of struct
uclamp_rq") introduced a bug where uclamp_max of the rq is not reset to
match the woken up task's uclamp_max when the rq is idle. This only
impacts the first wake up after enabling the static key. And it only
matters if the uclamp_max of this task is < 1024 since only then its
uclamp_max will be effectively ignored.

Fix it by properly initializing rq->uclamp_flags = UCLAMP_FLAG_IDLE to
ensure we reset rq uclamp_max when waking up from idle.

Fixes: d81ae8aac85c ("sched/uclamp: Fix initialization of struct uclamp_rq")
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
---
kernel/sched/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index beaa8be6241e..52b0c7513a32 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1929,7 +1929,7 @@ static void __init init_uclamp_rq(struct rq *rq)
};
}

- rq->uclamp_flags = 0;
+ rq->uclamp_flags = UCLAMP_FLAG_IDLE;
}

static void __init init_uclamp(void)
--
2.25.1