linux-kernel - [PATCH 3/3 v3] genirq: Remove cpumask availability check on kthread affinity setting

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Message-ID: <20251121143500.42111-4-frederic@kernel.org>
Date: Fri, 21 Nov 2025 15:35:00 +0100
From: Frederic Weisbecker <frederic@...nel.org>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>,
	Frederic Weisbecker <frederic@...nel.org>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Marco Crivellari <marco.crivellari@...e.com>,
	Waiman Long <llong@...hat.com>,
	cgroups@...r.kernel.org
Subject: [PATCH 3/3 v3] genirq: Remove cpumask availability check on kthread affinity setting

Failing to allocate the affinity mask of an interrupt descriptor fails the
whole descriptor initialization. It is then guaranteed that the cpumask is
always available whenever the related interrupt objects are alive, such as
the kthread handler.

Therefore remove the superfluous check since it is merely just a historical
leftover. Get rid also of the comments above it that are either obsolete or
useless.

Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Link: https://patch.msgid.link/20251118143052.68778-3-frederic@kernel.org
---
 kernel/irq/manage.c | 17 ++++-------------
 1 file changed, 4 insertions(+), 13 deletions(-)

diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 98b9b8b4de27..76c7b58f54c8 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -1001,7 +1001,6 @@ static irqreturn_t irq_forced_secondary_handler(int irq, void *dev_id)
 static void irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *action)
 {
 	cpumask_var_t mask;
-	bool valid = false;
 
 	if (!test_and_clear_bit(IRQTF_AFFINITY, &action->thread_flags))
 		return;
@@ -1018,21 +1017,13 @@ static void irq_thread_check_affinity(struct irq_desc *desc, struct irqaction *a
 	}
 
 	scoped_guard(raw_spinlock_irq, &desc->lock) {
-		/*
-		 * This code is triggered unconditionally. Check the affinity
-		 * mask pointer. For CPU_MASK_OFFSTACK=n this is optimized out.
-		 */
-		if (cpumask_available(desc->irq_common_data.affinity)) {
-			const struct cpumask *m;
+		const struct cpumask *m;
 
-			m = irq_data_get_effective_affinity_mask(&desc->irq_data);
-			cpumask_copy(mask, m);
-			valid = true;
-		}
+		m = irq_data_get_effective_affinity_mask(&desc->irq_data);
+		cpumask_copy(mask, m);
 	}
 
-	if (valid)
-		set_cpus_allowed_ptr(current, mask);
+	set_cpus_allowed_ptr(current, mask);
 	free_cpumask_var(mask);
 }
 #else
-- 
2.51.1