genirq: add reverse iterator for irq_desc

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 38bf89f2ade0e07a1c315218131db7a9a11038e1..31632aa65d16a335e5bc03ad651bc53aeb48a6c9 100644 (file)
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -21,6 +21,10 @@ extern int nr_irqs;
 
 # define for_each_irq_desc(irq, desc)          \
        for (irq = 0, desc = irq_desc; irq < nr_irqs; irq++, desc++)
+
+# define for_each_irq_desc_reverse(irq, desc)                  \
+       for (irq = nr_irqs -1, desc = irq_desc + (nr_irqs -1 ); \
+            irq > 0; irq--, desc--)
 #endif
 
 #ifndef CONFIG_S390