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From:   Yajun Deng <yajun.deng@linux.dev>
To:     mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
        bristot@redhat.com, vschneid@redhat.com
Cc:     linux-kernel@vger.kernel.org, Yajun Deng <yajun.deng@linux.dev>
Subject: [PATCH v7 2/3] sched/rt: Init 'back' in init_tg_rt_entry
Date:   Mon,  9 Oct 2023 20:22:43 +0800
Message-Id: <20231009122244.2394336-3-yajun.deng@linux.dev>
In-Reply-To: <20231009122244.2394336-1-yajun.deng@linux.dev>
References: <20231009122244.2394336-1-yajun.deng@linux.dev>
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The member 'back' in struct sched_rt_entity only related to
CONFIG_RT_GROUP_SCHED, so there is no need to init it in dequeue_rt_stack.

Init the member 'back' in init_tg_rt_entry.

Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
---
v7: Init 'back' in init_tg_rt_entry.
v6: Independent patch.
v5: Resend it.
v4: Missed rt_se = root in dequeue_rt_stack().
v3: Keep parent is NULL in init_tg_rt_entry().
v2: Add WARN_ON_ONCE in init_tg_rt_entry().
v1: https://lore.kernel.org/all/20230801062714.3424299-1-yajun.deng@linux.dev/
---
 kernel/sched/rt.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 642edbd24ffb..0d9e83c6fb71 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -233,8 +233,10 @@ void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
 
 	if (!parent)
 		rt_se->rt_rq = &rq->rt;
-	else
+	else {
 		rt_se->rt_rq = parent->my_q;
+		parent->back = rt_se;
+	}
 
 	rt_se->my_q = rt_rq;
 	rt_se->parent = parent;
@@ -1444,10 +1446,8 @@ static void dequeue_rt_stack(struct sched_rt_entity *rt_se, unsigned int flags)
 	struct sched_rt_entity *back = NULL;
 	unsigned int rt_nr_running;
 
-	for_each_sched_rt_entity(rt_se) {
-		rt_se->back = back;
+	for_each_sched_rt_entity(rt_se)
 		back = rt_se;
-	}
 
 	rt_nr_running = rt_rq_of_se(back)->rt_nr_running;
 
-- 
2.25.1