linux-kernel - [PATCH 09/14] sched: Make __do_set_cpus_allowed() use the sched

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Message-ID: <20250910155809.336621043@infradead.org>
Date: Wed, 10 Sep 2025 17:44:18 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: tj@...nel.org
Cc: linux-kernel@...r.kernel.org,
 peterz@...radead.org,
 mingo@...hat.com,
 juri.lelli@...hat.com,
 vincent.guittot@...aro.org,
 dietmar.eggemann@....com,
 rostedt@...dmis.org,
 bsegall@...gle.com,
 mgorman@...e.de,
 vschneid@...hat.com,
 longman@...hat.com,
 hannes@...xchg.org,
 mkoutny@...e.com,
 void@...ifault.com,
 arighi@...dia.com,
 changwoo@...lia.com,
 cgroups@...r.kernel.org,
 sched-ext@...ts.linux.dev,
 liuwenfang@...or.com,
 tglx@...utronix.de
Subject: [PATCH 09/14] sched: Make __do_set_cpus_allowed() use the sched_change pattern

Now that do_set_cpus_allowed() holds all the regular locks, convert it
to use the sched_change pattern helper.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
 kernel/sched/core.c |   26 +++++---------------------
 1 file changed, 5 insertions(+), 21 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2697,28 +2697,12 @@ void set_cpus_allowed_common(struct task
 static void
 do_set_cpus_allowed(struct task_struct *p, struct affinity_context *ctx)
 {
-	struct rq *rq = task_rq(p);
-	bool queued, running;
+	u32 flags = DEQUEUE_SAVE | DEQUEUE_NOCLOCK;
 
-	lockdep_assert_held(&p->pi_lock);
-	lockdep_assert_rq_held(rq);
-
-	queued = task_on_rq_queued(p);
-	running = task_current_donor(rq, p);
-
-	if (queued)
-		dequeue_task(rq, p, DEQUEUE_SAVE | DEQUEUE_NOCLOCK);
-
-	if (running)
-		put_prev_task(rq, p);
-
-	p->sched_class->set_cpus_allowed(p, ctx);
-	mm_set_cpus_allowed(p->mm, ctx->new_mask);
-
-	if (queued)
-		enqueue_task(rq, p, ENQUEUE_RESTORE | ENQUEUE_NOCLOCK);
-	if (running)
-		set_next_task(rq, p);
+	scoped_guard (sched_change, p, flags) {
+		p->sched_class->set_cpus_allowed(p, ctx);
+		mm_set_cpus_allowed(p->mm, ctx->new_mask);
+	}
 }
 
 /*