linux-kernel - [PATCH v2 4/7] irqchip/loongson-eiointc: Avoid explicit cpumask allocation on stack

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Date: Tue, 16 Apr 2024 16:54:51 +0800
From: Dawei Li <dawei.li@...ngroup.cn>
To: tglx@...utronix.de,
	yury.norov@...il.com,
	rafael@...nel.org
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,
	daniel.lezcano@...aro.org,
	linux-kernel@...r.kernel.org,
	Dawei Li <dawei.li@...ngroup.cn>
Subject: [PATCH v2 4/7] irqchip/loongson-eiointc: 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-loongson-eiointc.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/drivers/irqchip/irq-loongson-eiointc.c b/drivers/irqchip/irq-loongson-eiointc.c
index 4f5e6d21d77d..c7ddebf312ad 100644
--- a/drivers/irqchip/irq-loongson-eiointc.c
+++ b/drivers/irqchip/irq-loongson-eiointc.c
@@ -93,19 +93,15 @@ static int eiointc_set_irq_affinity(struct irq_data *d, const struct cpumask *af
 	unsigned int cpu;
 	unsigned long flags;
 	uint32_t vector, regaddr;
-	struct cpumask intersect_affinity;
 	struct eiointc_priv *priv = d->domain->host_data;
 
 	raw_spin_lock_irqsave(&affinity_lock, flags);
 
-	cpumask_and(&intersect_affinity, affinity, cpu_online_mask);
-	cpumask_and(&intersect_affinity, &intersect_affinity, &priv->cpuspan_map);
-
-	if (cpumask_empty(&intersect_affinity)) {
+	cpu = cpumask_first_and_and(&priv->cpuspan_map, affinity, cpu_online_mask);
+	if (cpu >= nr_cpu_ids) {
 		raw_spin_unlock_irqrestore(&affinity_lock, flags);
 		return -EINVAL;
 	}
-	cpu = cpumask_first(&intersect_affinity);
 
 	vector = d->hwirq;
 	regaddr = EIOINTC_REG_ENABLE + ((vector >> 5) << 2);
-- 
2.27.0