linux-kernel - [RFC PATCH v4 06/28] sched/rt: Remove rq field in struct rt

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Message-ID: <20251201124205.11169-7-yurand2000@gmail.com>
Date: Mon,  1 Dec 2025 13:41:39 +0100
From: Yuri Andriaccio <yurand2000@...il.com>
To: Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Juri Lelli <juri.lelli@...hat.com>,
	Vincent Guittot <vincent.guittot@...aro.org>,
	Dietmar Eggemann <dietmar.eggemann@....com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ben Segall <bsegall@...gle.com>,
	Mel Gorman <mgorman@...e.de>,
	Valentin Schneider <vschneid@...hat.com>
Cc: linux-kernel@...r.kernel.org,
	Luca Abeni <luca.abeni@...tannapisa.it>,
	Yuri Andriaccio <yuri.andriaccio@...tannapisa.it>
Subject: [RFC PATCH v4 06/28] sched/rt: Remove rq field in struct rt_rq

The rq field now is just caching the pointer to the global runqueue of the
given rt_rq, so it is unnecessary as the global runqueue can be retrieved
in other ways.

Signed-off-by: Yuri Andriaccio <yurand2000@...il.com>
---
 kernel/sched/rt.c    |  7 ++-----
 kernel/sched/sched.h | 19 +++++++++++++------
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 74038b27f8..21f4e94235 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -100,10 +100,7 @@ void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
 		struct sched_rt_entity *rt_se, int cpu,
 		struct sched_rt_entity *parent)
 {
-	struct rq *rq = cpu_rq(cpu);
-
 	rt_rq->highest_prio.curr = MAX_RT_PRIO-1;
-	rt_rq->rq = rq;
 	rt_rq->tg = tg;
 
 	tg->rt_rq[cpu] = rt_rq;
@@ -183,7 +180,7 @@ static void pull_rt_task(struct rq *);
 
 static inline void rt_queue_push_tasks(struct rt_rq *rt_rq)
 {
-	struct rq *rq = container_of(rt_rq, struct rq, rt);
+	struct rq *rq = served_rq_of_rt_rq(rt_rq);
 
 	if (!has_pushable_tasks(rt_rq))
 		return;
@@ -193,7 +190,7 @@ static inline void rt_queue_push_tasks(struct rt_rq *rt_rq)
 
 static inline void rt_queue_pull_task(struct rt_rq *rt_rq)
 {
-	struct rq *rq = container_of(rt_rq, struct rq, rt);
+	struct rq *rq = served_rq_of_rt_rq(rt_rq);
 
 	queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);
 }
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 5c48d6a5e6..1896c4e247 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -3074,11 +3074,16 @@ static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
 	return container_of(rt_se, struct task_struct, rt);
 }
 
+static inline struct rq *served_rq_of_rt_rq(struct rt_rq *rt_rq)
+{
+	WARN_ON(!rt_group_sched_enabled() && rt_rq->tg != &root_task_group);
+	return container_of(rt_rq, struct rq, rt);
+}
+
 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
 {
 	/* Cannot fold with non-CONFIG_RT_GROUP_SCHED version, layout */
-	WARN_ON(!rt_group_sched_enabled() && rt_rq->tg != &root_task_group);
-	return rt_rq->rq;
+	return cpu_rq(served_rq_of_rt_rq(rt_rq)->cpu);
 }
 
 static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
@@ -3089,10 +3094,7 @@ static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
 
 static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
 {
-	struct rt_rq *rt_rq = rt_se->rt_rq;
-
-	WARN_ON(!rt_group_sched_enabled() && rt_rq->tg != &root_task_group);
-	return rt_rq->rq;
+	return rq_of_rt_rq(rt_se->rt_rq);
 }
 #else
 static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
@@ -3100,6 +3102,11 @@ static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
 	return container_of(rt_se, struct task_struct, rt);
 }
 
+static inline struct rq *served_rq_of_rt_rq(struct rt_rq *rt_rq)
+{
+	return container_of(rt_rq, struct rq, rt);
+}
+
 static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
 {
 	return container_of(rt_rq, struct rq, rt);
-- 
2.51.0