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

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Message-ID: <47910F8F.3040107@pobox.com>
Date:	Fri, 18 Jan 2008 15:43:59 -0500
From:	Jeff Garzik <jgarzik@...ox.com>
To:	Rusty Russell <rusty@...tcorp.com.au>
CC:	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ash Willis <ashwillis@...grammer.net>,
	linux-pcmcia@...ts.infradead.org,
	virtualization@...ts.linux-foundation.org,
	Tejun Heo <htejun@...il.com>
Subject: Re: [PATCH 2/3] Make IRQ handlers typesafe.

Rusty Russell wrote:
> 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 <rusty@...tcorp.com.au>
> ---
>  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);

This is ugly and unnecessary.

Anything that does not use irq_handler_t is broken and should be fixed 
(as noted in last email, I think I've covered all this driver work already)

And if by definition everything uses irq_handler_t, there is no need for 
any of this "check_either_type" silliness.

	Jeff


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