linux-kernel - [PATCH 2/4] lib/group_cpus: relax atomicity requirement in grp_spread_init

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Date:   Wed,  1 Nov 2023 15:58:18 -0700
From:   Yury Norov <yury.norov@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org
Cc:     Yury Norov <yury.norov@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>
Subject: [PATCH 2/4] lib/group_cpus: relax atomicity requirement in grp_spread_init_one()

Because the function is called with cpus_read_lock() held, all the masks
involved are stabilized, and thus any 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 aa3f6815bb12..b1e7d9cc9da9 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--;
 		}
 	}
-- 
2.39.2