kernel: Don't allow IRQ affinity masks to have more than one CPU

Even with an affinity mask that has multiple CPUs set, IRQs always run on the first CPU in their affinity mask. Drivers that register an IRQ affinity notifier (such as pm_qos) will therefore have an incorrect assumption of where an IRQ is affined. Fix the IRQ affinity mask deception by forcing it to only contain one set CPU. Signed-off-by: Sultan Alsawaf <[email protected]> Signed-off-by: celtare21 <[email protected]>
celtare21 · Dec 16, 2022 · 321dd8d · 321dd8d
1 parent f33472a
commit 321dd8d
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
@@ -228,6 +228,9 @@ int irq_do_set_affinity(struct irq_data *data, const struct cpumask *mask,
 	if (!chip || !chip->irq_set_affinity)
 		return -EINVAL;
 
+	/* IRQs only run on the first CPU in the affinity mask; reflect that */
+	mask = cpumask_of(cpumask_first(mask));
+
 	/*
 	 * If this is a managed interrupt and housekeeping is enabled on
 	 * it check whether the requested affinity mask intersects with