linux-kernel - [PATCH 5/6] irqchip/riscv-aplic-direct: Avoid explicit cpumask allocation on stack

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Message-Id: <20240412105839.2896281-6-dawei.li@shingroup.cn>
Date: Fri, 12 Apr 2024 18:58:38 +0800
From: Dawei Li <dawei.li@...ngroup.cn>
To: tglx@...utronix.de,
	yury.norov@...il.com
Cc: akpm@...ux-foundation.org,
	maz@...nel.org,
	florian.fainelli@...adcom.com,
	chenhuacai@...nel.org,
	jiaxun.yang@...goat.com,
	anup@...infault.org,
	palmer@...belt.com,
	samuel.holland@...ive.com,
	linux@...musvillemoes.dk,
	linux-kernel@...r.kernel.org,
	Dawei Li <dawei.li@...ngroup.cn>
Subject: [PATCH 5/6] irqchip/riscv-aplic-direct: Avoid explicit cpumask allocation on stack

In general it's preferable to avoid placing cpumasks on the stack, as
for large values of NR_CPUS these can consume significant amounts of
stack space and make stack overflows more likely.

Use cpumask_first_and_and() to avoid the need for a temporary cpumask on
the stack.

Signed-off-by: Dawei Li <dawei.li@...ngroup.cn>
---
 drivers/irqchip/irq-riscv-aplic-direct.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/irqchip/irq-riscv-aplic-direct.c b/drivers/irqchip/irq-riscv-aplic-direct.c
index 06bace9b7497..5cb7d74d0927 100644
--- a/drivers/irqchip/irq-riscv-aplic-direct.c
+++ b/drivers/irqchip/irq-riscv-aplic-direct.c
@@ -54,15 +54,13 @@ static int aplic_direct_set_affinity(struct irq_data *d, const struct cpumask *m
 	struct aplic_direct *direct = container_of(priv, struct aplic_direct, priv);
 	struct aplic_idc *idc;
 	unsigned int cpu, val;
-	struct cpumask amask;
 	void __iomem *target;
 
-	cpumask_and(&amask, &direct->lmask, mask_val);
-
 	if (force)
-		cpu = cpumask_first(&amask);
+		cpu = cpumask_first_and(&direct->lmask, mask_val);
 	else
-		cpu = cpumask_any_and(&amask, cpu_online_mask);
+		cpu = cpumask_first_and_and(&direct->lmask, mask_val,
+					    cpu_online_mask);
 
 	if (cpu >= nr_cpu_ids)
 		return -EINVAL;
-- 
2.27.0