Re: [PATCH] expand_resource

[Russell King <rmk@arm.linux.org.uk>]

On Tue, Sep 30, 2003 at 10:04:10PM +0100, Matthew Wilcox wrote:
> Rewrite expand_resource() to be racefree and move it to kernel/resource.c.
> 
>...
> +/*
> + * Expand an existing resource by size amount.
> + */
> +int expand_resource(struct resource *res, unsigned long size,
> +			   unsigned long align)
> +{

Could we have the kerneldoc stuff added to this function?  My main
question though is - what is the intended purpose of "align" ?  As
it is implemented, it seems to have a weird behaviour:

- if we expand the "end" of the resource, we round it towards an
  address which is a multiple of align, but "start" may not be
  a multiple of align.
- if we expand "start", we round it down towards a multiple of
  align.  However, "end" may not be a multiple of align.

This may actually be of use to PCMCIA IO space handling - we only
have two windows, but we may need to expand them if we have a multi-
function card if we have more than 2 areas to map.  In this case,
we'd need to know whether "start" was expanded or "end" was expanded
since we can't change the use of the already-allocated resource.

It may make sense to do something more generic, like:

int adjust_resource(struct resource *res, unsigned long start,
		    unsigned long end);

so that the caller knows what he's requesting and knows whether that
change succeeded or failed.  However, it is something I'd need to
look deeper into when I have more time available to look at such
stuff, so please don't take the above as a well thought-out solution.

-- 
Russell King (rmk@arm.linux.org.uk)	http://www.arm.linux.org.uk/personal/
      Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
      maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                      2.6 Serial core