linux-kernel - [PATCH 6/6] irqchip/sifive-plic: Avoid explicit cpumask allocation on stack

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Message-Id: <20240412105839.2896281-7-dawei.li@shingroup.cn>
Date: Fri, 12 Apr 2024 18:58:39 +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 6/6] irqchip/sifive-plic: 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-sifive-plic.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index f3d4cb9e34f7..bf5d2fc6396e 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -164,15 +164,13 @@ static int plic_set_affinity(struct irq_data *d,
 			     const struct cpumask *mask_val, bool force)
 {
 	unsigned int cpu;
-	struct cpumask amask;
 	struct plic_priv *priv = irq_data_get_irq_chip_data(d);
 
-	cpumask_and(&amask, &priv->lmask, mask_val);
-
 	if (force)
-		cpu = cpumask_first(&amask);
+		cpu = cpumask_first_and(&priv->lmask, mask_val);
 	else
-		cpu = cpumask_any_and(&amask, cpu_online_mask);
+		cpu = cpumask_first_and_and(&priv->lmask, mask_val,
+					    cpu_online_mask);
 
 	if (cpu >= nr_cpu_ids)
 		return -EINVAL;
-- 
2.27.0