genirq: use inline function for irq_to_desc

For the non sparse irq case an inline function is perfectly fine.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/irq.h

@@ -204,8 +204,6 @@ struct irq_desc {
 	const char		*name;
 } ____cacheline_internodealigned_in_smp;
 
-extern struct irq_desc *irq_to_desc(unsigned int irq);
-extern struct irq_desc *irq_to_desc_alloc(unsigned int irq);
 
 #ifndef CONFIG_HAVE_SPARSE_IRQ
 
@@ -216,8 +214,21 @@ extern struct irq_desc irq_desc[NR_IRQS];
 extern struct irq_desc *irq_desc;
 #endif
 
+static inline struct irq_desc *irq_to_desc(unsigned int irq)
+{
+	return (irq < nr_irqs) ? irq_desc + irq : NULL;
+}
+
+static inline struct irq_desc *irq_to_desc_alloc(unsigned int irq)
+{
+	return irq_to_desc(irq);
+}
+
 #else
 
+extern struct irq_desc *irq_to_desc(unsigned int irq);
+extern struct irq_desc *irq_to_desc_alloc(unsigned int irq);
+
 extern struct irq_desc *sparse_irqs;
 #define for_each_irq_desc(irqX, desc)		\
 	for (desc = sparse_irqs, irqX = desc->irq; desc; desc = desc->next, irqX = desc ? desc->irq : -1U)

kernel/irq/handle.c

@@ -262,20 +262,6 @@ struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
 
 #endif
 
-#ifndef CONFIG_HAVE_SPARSE_IRQ
-struct irq_desc *irq_to_desc(unsigned int irq)
-{
-	if (irq < nr_irqs)
-		return &irq_desc[irq];
-
-	return NULL;
-}
-struct irq_desc *irq_to_desc_alloc(unsigned int irq)
-{
-	return irq_to_desc(irq);
-}
-#endif
-
 /*
  * What should we do if we get a hw irq event on an illegal vector?
  * Each architecture has to answer this themself.