Re: [PATCH 2/3] Make IRQ handlers typesafe.

This patch lets interrupt handler functions have their natural type
(ie. exactly match the data pointer type); for transition it allows
the old irq_handler_t type as well.

To do this it uses a gcc extension, cast-to-union, which allows a type
to be cast to any type within the union.  When used in a wrapper
macro, it's a simple way of allowing one of several types.

(Some drivers now need to be cleaned up to compile, previous patch).

Signed-off-by: Rusty Russell <redacted>
---
 include/linux/interrupt.h |   17 +++++++++++++++--
 include/linux/kernel.h    |    7 +++++++
 kernel/irq/devres.c       |   10 +++++-----
 kernel/irq/manage.c       |    6 +++---
 4 files changed, 30 insertions(+), 10 deletions(-)

diff -r 0fe1a980708b include/linux/interrupt.h

--- a/include/linux/interrupt.h	Thu Jan 17 14:48:56 2008 +1100
+++ b/include/linux/interrupt.h	Thu Jan 17 15:42:01 2008 +1100

@@ -69,13 +69,26 @@ struct irqaction {
 };
 
 extern irqreturn_t no_action(int cpl, void *dev_id);
-extern int __must_check request_irq(unsigned int, irq_handler_t handler,
+
+/* Typesafe version of request_irq.  Also takes old-style void * handlers. */
+#define request_irq(irq, handler, flags, name, dev_id)			\
+	__request_irq((irq),						\
+		      check_either_type((handler), irq_handler_t,	\
+					int (*)(int, typeof(dev_id))),	\
+		      (flags), (name), (dev_id))
+
+extern int __must_check __request_irq(unsigned int, irq_handler_t handler,
 		       unsigned long, const char *, void *);
 extern void free_irq(unsigned int, void *);
 
 struct device;
 
-extern int __must_check devm_request_irq(struct device *dev, unsigned int irq,
+#define devm_request_irq(dev, irq, handler, flags, name, dev_id)	\
+	__devm_request_irq((dev), (irq),				\
+		      check_either_type((handler), irq_handler_t,	\
+					int (*)(int, typeof(dev_id))),	\
+		      (flags), (name), (dev_id))
+extern int __must_check __devm_request_irq(struct device *dev, unsigned int irq,
 			    irq_handler_t handler, unsigned long irqflags,
 			    const char *devname, void *dev_id);