linux-kernel - [PATCH 3/7] RDMA: hfi1: simplify find_hw_thread

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Message-ID: <20250604193947.11834-4-yury.norov@gmail.com>
Date: Wed,  4 Jun 2025 15:39:39 -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 3/7] RDMA: hfi1: simplify find_hw_thread_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.

Signed-off-by: Yury Norov [NVIDIA] <yury.norov@...il.com>
---
 drivers/infiniband/hw/hfi1/affinity.c | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/affinity.c b/drivers/infiniband/hw/hfi1/affinity.c
index f2c530ab85a5..9ea80b777061 100644
--- a/drivers/infiniband/hw/hfi1/affinity.c
+++ b/drivers/infiniband/hw/hfi1/affinity.c
@@ -963,7 +963,7 @@ void hfi1_put_irq_affinity(struct hfi1_devdata *dd,
 static void find_hw_thread_mask(uint hw_thread_no, cpumask_var_t hw_thread_mask,
 				struct hfi1_affinity_node_list *affinity)
 {
-	int possible, curr_cpu, i;
+	int curr_cpu;
 	uint num_cores_per_socket;
 
 	cpumask_copy(hw_thread_mask, &affinity->proc.mask);
@@ -976,17 +976,9 @@ static void find_hw_thread_mask(uint hw_thread_no, cpumask_var_t hw_thread_mask,
 						node_affinity.num_online_nodes;
 
 	/* Removing other siblings not needed for now */
-	possible = cpumask_weight(hw_thread_mask);
-	curr_cpu = cpumask_first(hw_thread_mask);
-	for (i = 0;
-	     i < num_cores_per_socket * node_affinity.num_online_nodes;
-	     i++)
-		curr_cpu = cpumask_next(curr_cpu, hw_thread_mask);
-
-	for (; i < possible; i++) {
-		cpumask_clear_cpu(curr_cpu, hw_thread_mask);
-		curr_cpu = cpumask_next(curr_cpu, hw_thread_mask);
-	}
+	curr_cpu = cpumask_cpumask_nth(num_cores_per_socket *
+			node_affinity.num_online_nodes, hw_thread_mask) + 1;
+	cpumask_clear_cpus(hw_thread_mask, curr_cpu, nr_cpu_ids - curr_cpu);
 
 	/* Identifying correct HW threads within physical cores */
 	cpumask_shift_left(hw_thread_mask, hw_thread_mask,
-- 
2.43.0