linux-kernel - Re: [PATCH 04/13] resource: Provide new functions to walk through resources

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Message-ID: <20140604102420.GC4105@pd.tnic>
Date:	Wed, 4 Jun 2014 12:24:20 +0200
From:	Borislav Petkov <bp@...en8.de>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
	ebiederm@...ssion.com, hpa@...or.com, mjg59@...f.ucam.org,
	greg@...ah.com, jkosina@...e.cz, dyoung@...hat.com,
	chaowang@...hat.com, bhe@...hat.com, akpm@...ux-foundation.org,
	Yinghai Lu <yinghai@...nel.org>
Subject: Re: [PATCH 04/13] resource: Provide new functions to walk through
 resources

On Tue, Jun 03, 2014 at 09:06:53AM -0400, Vivek Goyal wrote:
> @@ -322,7 +327,71 @@ int release_resource(struct resource *old)
>  
>  EXPORT_SYMBOL(release_resource);
>  
> -#if !defined(CONFIG_ARCH_HAS_WALK_MEMORY)
> +/*
> + * Finds the lowest iomem reosurce exists with-in [res->start.res->end)
> + * the caller must specify res->start, res->end, res->flags and "name".
> + * If found, returns 0, res is overwritten, if not found, returns -1.
> + * This walks through whole tree and not just first level children.
> + */
> +static int find_next_iomem_res(struct resource *res, char *name)
> +{
> +	resource_size_t start, end;
> +	struct resource *p;
> +
> +	BUG_ON(!res);
> +
> +	start = res->start;
> +	end = res->end;
> +	BUG_ON(start >= end);
> +
> +	read_lock(&resource_lock);
> +	p = &iomem_resource;
> +	while ((p = next_resource(p))) {

Just a thought - this function differs from find_next_system_ram() only
in the traversal mode through resources. I wonder if next_resource()
could be given a flag, say TRAVERSE_SIBLINGS_ONLY or so and be called
from both, once with the flag set and once without and thus save us the
code duplication.

> +		if (p->flags != res->flags)
> +			continue;
> +		if (name && strcmp(p->name, name))
> +			continue;
> +		if (p->start > end) {
> +			p = NULL;
> +			break;
> +		}
> +		if ((p->end >= start) && (p->start < end))
> +			break;
> +	}
> +
> +	read_unlock(&resource_lock);
> +	if (!p)
> +		return -1;
> +	/* copy data */
> +	if (res->start < p->start)
> +		res->start = p->start;
> +	if (res->end > p->end)
> +		res->end = p->end;
> +	return 0;
> +}

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
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