On 2014/9/17 1:45, Thomas Gleixner wrote:

On Thu, 11 Sep 2014, Jiang Liu wrote:

quoted

+#ifdef	CONFIG_IRQ_DOMAIN_HIERARCHY
+void irq_chip_ack_parent(struct irq_data *data)
+{
+	data = data->parent_data;
+	if (data && data->chip && data->chip->irq_ack)
+		data->chip->irq_ack(data);

Why is this restricted to a single parent level and does not go down
the whole stack?

Hi Thomas,
	It happens to work on x86, and we want to achieve a bit
performance advantage by not walking down the whole stack.
If preferred, I will change it to walk the whole stack.
Regards!
Gerry

Thanks,

	tglx