genirq: add reverse iterator for irq_desc

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

1 files changed, 4 insertions, 0 deletions

diff --git a/include/linux/irq.h b/include/linux/irq.h
index 38bf89f2ade0..31632aa65d16 100644
--- 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