genirq: Uninline and sanity check generic_handle_irq()

generic_handle_irq() is missing a NULL pointer check for the result of
irq_to_desc. This was a not a big problem, but we want to expose it to
drivers, so we better have sanity checks in place. Add a return value
as well, which indicates that the irq number was valid and the handler
was invoked.

Based on the pure code move from Jonathan Cameron.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jonathan Cameron <jic23@cam.ac.uk>

include/linux/irqdesc.h

@@ -111,10 +111,7 @@ static inline void generic_handle_irq_desc(unsigned int irq, struct irq_desc *de
 	desc->handle_irq(irq, desc);
 }
 
-static inline void generic_handle_irq(unsigned int irq)
-{
-	generic_handle_irq_desc(irq, irq_to_desc(irq));
-}
+int generic_handle_irq(unsigned int irq);
 
 /* Test to see if a driver has successfully requested an irq */
 static inline int irq_has_action(unsigned int irq)

kernel/irq/irqdesc.c

@@ -290,6 +290,21 @@ static int irq_expand_nr_irqs(unsigned int nr)
 
 #endif /* !CONFIG_SPARSE_IRQ */
 
+/**
+ * generic_handle_irq - Invoke the handler for a particular irq
+ * @irq:	The irq number to handle
+ *
+ */
+int generic_handle_irq(unsigned int irq)
+{
+	struct irq_desc *desc = irq_to_desc(irq);
+
+	if (!desc)
+		return -EINVAL;
+	generic_handle_irq_desc(irq, desc);
+	return 0;
+}
+
 /* Dynamic interrupt handling */
 
 /**