Re: [patch 1/1] [RFC] uml: add and use generic hw_controller_type->release

[Chris Wedgwood <cw@f00f.org>]

On Fri, May 27, 2005 at 02:39:26AM +0200, blaisorblade@yahoo.it wrote:

> From: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>, Chris Wedgwood <cw@f00f.org>
> CC: Ingo Molnar <mingo@redhat.com>

[...]

> This is heavily based on some work by Chris Wedgwood, which however
> didn't get the patch merged for something I'd call a
> "misunderstanding" (the need for this patch wasn't cleanly
> explained, thus adding the generic hook was felt as undesirable).

Looks very reasonable to me and your explaination is much better than
mine was :-)

> diff -puN kernel/irq/manage.c~uml-gen-irq-release kernel/irq/manage.c
> --- linux-2.6.git/kernel/irq/manage.c~uml-gen-irq-release	2005-05-25 01:15:46.000000000 +0200
> +++ linux-2.6.git-paolo/kernel/irq/manage.c	2005-05-25 01:15:46.000000000 +0200
> @@ -255,6 +255,10 @@ void free_irq(unsigned int irq, void *de
>  
>  			/* Found it - now remove it from the list of entries */
>  			*pp = action->next;
> +
> +			if (desc->handler->release)
> +				desc->handler->release(irq, dev_id);
> +

Because right now we know the *only* port that needs a release method
is UML I wonder if we could do save a couple of bytes & cycles for
everyone else by doing something like #ifdef CONFIG_IRQ_HAS_RELEASE,
#endif around that and then letting the Kconfig magic set
CONFIG_IRQ_HAS_RELEASE as required?  If other arches need it thay can
do the same and if eventually almost everyone does we can kill the
#ifdef crud?

Longer term I wonder if some of the irq mechanics in UML couldn't end
up being a bit more like the s390 stuff too?