linux-kernel - [PATCH] genirq: Allow NULL affinity for setup_percpu

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Message-ID: <20251205091814.3944205-1-maz@kernel.org>
Date: Fri,  5 Dec 2025 09:18:14 +0000
From: Marc Zyngier <maz@...nel.org>
To: linux-kernel@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Daniel Thompson <danielt@...nel.org>
Subject: [PATCH] genirq: Allow NULL affinity for setup_percpu_irq()

setup_percpu_irq() was forgotten when the percpu_devid infrastructure
was updated to deal with CPU affinities.

In order to keep ignoring users of this legacy API, provide sensible
defaults by setting the affinity to cpu_online_mask if none was
provided by the caller.

Reported-by: Daniel Thompson <danielt@...nel.org>
Closes: https://lore.kernel.org/r/aTFozefMQRg7lYxh@aspen.lan
Fixes: bdf4e2ac295fe ("genirq: Allow per-cpu interrupt sharing for non-overlapping affinities")
Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 kernel/irq/manage.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 0bb29316b4362..8b1b4c8a4f54c 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -2470,6 +2470,9 @@ int setup_percpu_irq(unsigned int irq, struct irqaction *act)
 	if (retval < 0)
 		return retval;
 
+	if (!act->affinity)
+		act->affinity = cpu_online_mask;
+
 	retval = __setup_irq(irq, desc, act);
 
 	if (retval)
-- 
2.47.3