linux-kernel - [PATCH 4/7] RDMA: hfi1: simplify init_real_cpu

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Message-ID: <20250604193947.11834-5-yury.norov@gmail.com>
Date: Wed,  4 Jun 2025 15:39:40 -0400
From: Yury Norov <yury.norov@...il.com>
To: Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Leon Romanovsky <leon@...nel.org>,
	Yury Norov <yury.norov@...il.com>,
	Rasmus Villemoes <linux@...musvillemoes.dk>,
	linux-rdma@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/7] RDMA: hfi1: simplify init_real_cpu_mask()

From: "Yury Norov [NVIDIA]" <yury.norov@...il.com>

The function opencodes cpumask_nth() and cpumask_clear_cpus(). The
dedicated helpers are easier to use and  usually much faster than
opencoded for-loops.

While there, drop useless clear of real_cpu_mask.

Signed-off-by: Yury Norov [NVIDIA] <yury.norov@...il.com>
---
 drivers/infiniband/hw/hfi1/affinity.c | 19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/affinity.c b/drivers/infiniband/hw/hfi1/affinity.c
index 9ea80b777061..b2884226827a 100644
--- a/drivers/infiniband/hw/hfi1/affinity.c
+++ b/drivers/infiniband/hw/hfi1/affinity.c
@@ -92,9 +92,7 @@ static void cpu_mask_set_put(struct cpu_mask_set *set, int cpu)
 /* Initialize non-HT cpu cores mask */
 void init_real_cpu_mask(void)
 {
-	int possible, curr_cpu, i, ht;
-
-	cpumask_clear(&node_affinity.real_cpu_mask);
+	int possible, curr_cpu, ht;
 
 	/* Start with cpu online mask as the real cpu mask */
 	cpumask_copy(&node_affinity.real_cpu_mask, cpu_online_mask);
@@ -110,17 +108,10 @@ void init_real_cpu_mask(void)
 	 * "real" cores.  Assumes that HT cores are not enumerated in
 	 * succession (except in the single core case).
 	 */
-	curr_cpu = cpumask_first(&node_affinity.real_cpu_mask);
-	for (i = 0; i < possible / ht; i++)
-		curr_cpu = cpumask_next(curr_cpu, &node_affinity.real_cpu_mask);
-	/*
-	 * Step 2.  Remove the remaining HT siblings.  Use cpumask_next() to
-	 * skip any gaps.
-	 */
-	for (; i < possible; i++) {
-		cpumask_clear_cpu(curr_cpu, &node_affinity.real_cpu_mask);
-		curr_cpu = cpumask_next(curr_cpu, &node_affinity.real_cpu_mask);
-	}
+	curr_cpu = cpumask_nth(possible / ht, &node_affinity.real_cpu_mask) + 1;
+
+	/* Step 2.  Remove the remaining HT siblings. */
+	cpumask_clear_cpus(&node_affinity.real_cpu_mask, curr_cpu, nr_cpu_ids - curr_cpu);
 }
 
 int node_affinity_init(void)
-- 
2.43.0