genirq: Warn when effective affinity is not updated

Emit a one time warning when the effective affinity mask is enabled in
Kconfig, but the interrupt chip does not update the mask in its
irq_set_affinity() callback,

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/alpine.DEB.2.20.1710042208400.2406@nanos

kernel/irq/manage.c

@@ -168,6 +168,19 @@ void irq_set_thread_affinity(struct irq_desc *desc)
 			set_bit(IRQTF_AFFINITY, &action->thread_flags);
 }
 
+static void irq_validate_effective_affinity(struct irq_data *data)
+{
+#ifdef CONFIG_GENERIC_IRQ_EFFECTIVE_AFF_MASK
+	const struct cpumask *m = irq_data_get_effective_affinity_mask(data);
+	struct irq_chip *chip = irq_data_get_irq_chip(data);
+
+	if (!cpumask_empty(m))
+		return;
+	pr_warn_once("irq_chip %s did not update eff. affinity mask of irq %u\n",
+		     chip->name, data->irq);
+#endif
+}
+
 int irq_do_set_affinity(struct irq_data *data, const struct cpumask *mask,
 			bool force)
 {
@@ -181,6 +194,7 @@ int irq_do_set_affinity(struct irq_data *data, const struct cpumask *mask,
 	case IRQ_SET_MASK_OK_DONE:
 		cpumask_copy(desc->irq_common_data.affinity, mask);
 	case IRQ_SET_MASK_OK_NOCOPY:
+		irq_validate_effective_affinity(data);
 		irq_set_thread_affinity(desc);
 		ret = 0;
 	}