irq: Add irq_node() primitive

... to return irq_desc node info without #ifdefs at the callsites.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
LKML-Reference: <4A95C350.8060308@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

include/linux/irqnr.h

@@ -41,6 +41,12 @@ extern struct irq_desc *irq_to_desc(unsigned int irq);
 			;						\
 		else
 
+#ifdef CONFIG_SMP
+#define irq_node(irq)	(irq_to_desc(irq)->node)
+#else
+#define irq_node(irq)	0
+#endif
+
 #endif /* CONFIG_GENERIC_HARDIRQS */
 
 #define for_each_irq_nr(irq)                   \