Index: linux-2.6.33.2/kernel/irq/chip.c
===================================================================
--- linux-2.6.33.2.orig/kernel/irq/chip.c	2010-04-02 01:02:33.000000000 +0200
+++ linux-2.6.33.2/kernel/irq/chip.c	2010-04-02 23:37:40.000000000 +0200
@@ -650,6 +650,9 @@
 
 	kstat_incr_irqs_this_cpu(irq, desc);
 
+	if (unlikely(!desc->action || (desc->status & IRQ_DISABLED)))
+		return;
+
 	if (desc->chip->ack)
 		desc->chip->ack(irq);