linux-kernel - [PATCH v2 2/6] lib/group_cpus: relax atomicity requirement in grp_spread_init

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Message-Id: <20231207203900.859776-3-yury.norov@gmail.com>
Date:   Thu,  7 Dec 2023 12:38:56 -0800
From:   Yury Norov <yury.norov@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Cc:     Yury Norov <yury.norov@...il.com>, Ming Lei <ming.lei@...hat.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: [PATCH v2 2/6] lib/group_cpus: relax atomicity requirement in grp_spread_init_one()

Because nmsk and irqmsk are stable, extra atomicity is not required.

Signed-off-by: Yury Norov <yury.norov@...il.com>
---
 lib/group_cpus.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/lib/group_cpus.c b/lib/group_cpus.c
index ee272c4cefcc..8eb18c6bbf3b 100644
--- a/lib/group_cpus.c
+++ b/lib/group_cpus.c
@@ -24,8 +24,8 @@ static void grp_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
 		if (cpu >= nr_cpu_ids)
 			return;
 
-		cpumask_clear_cpu(cpu, nmsk);
-		cpumask_set_cpu(cpu, irqmsk);
+		__cpumask_clear_cpu(cpu, nmsk);
+		__cpumask_set_cpu(cpu, irqmsk);
 		cpus_per_grp--;
 
 		/* If the cpu has siblings, use them first */
@@ -34,9 +34,8 @@ static void grp_spread_init_one(struct cpumask *irqmsk, struct cpumask *nmsk,
 			sibl = cpumask_next(sibl, siblmsk);
 			if (sibl >= nr_cpu_ids)
 				break;
-			if (!cpumask_test_and_clear_cpu(sibl, nmsk))
-				continue;
-			cpumask_set_cpu(sibl, irqmsk);
+			__cpumask_clear_cpu(sibl, nmsk);
+			__cpumask_set_cpu(sibl, irqmsk);
 			cpus_per_grp--;
 		}
 	}
-- 
2.40.1