linux-kernel - [patch V2 08/20] sched/mmcid: Use cpumask_or_and_calc

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Message-ID: <20251022110555.901055185@linutronix.de>
Date: Wed, 22 Oct 2025 14:55:29 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Peter Zijlstra <peterz@...radead.org>,
 Gabriele Monaco <gmonaco@...hat.com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Michael Jeanson <mjeanson@...icios.com>,
 Jens Axboe <axboe@...nel.dk>,
 "Paul E. McKenney" <paulmck@...nel.org>,
 "Gautham R. Shenoy" <gautham.shenoy@....com>,
 Florian Weimer <fweimer@...hat.com>,
 Tim Chen <tim.c.chen@...el.com>,
 Yury Norov <yury.norov@...il.com>
Subject: [patch V2 08/20] sched/mmcid: Use cpumask_or_and_calc_weight()

Use cpumask_or_and_calc_weight() instead of cpumask_or() and
cpumask_weight() on the result, which walks the same bitmap twice.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 kernel/sched/core.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -10375,6 +10375,7 @@ void call_trace_sched_update_nr_running(
 static inline void mm_update_cpus_allowed(struct mm_struct *mm, const struct cpumask *affmsk)
 {
 	struct cpumask *mm_allowed;
+	unsigned int weight;

 	if (!mm)
 		return;
@@ -10385,8 +10386,8 @@ static inline void mm_update_cpus_allowe
 	 */
 	guard(raw_spinlock)(&mm->mm_cid.lock);
 	mm_allowed = mm_cpus_allowed(mm);
-	cpumask_or(mm_allowed, mm_allowed, affmsk);
-	WRITE_ONCE(mm->mm_cid.nr_cpus_allowed, cpumask_weight(mm_allowed));
+	weight = cpumask_or_and_calc_weight(mm_allowed, mm_allowed, affmsk);
+	WRITE_ONCE(mm->mm_cid.nr_cpus_allowed, weight);
 }

 void sched_mm_cid_exit_signals(struct task_struct *t)