linux-kernel - Re: [PATCH 18/39] lmb: Add lmb_reserve_area_overlap

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Date:	Tue, 13 Apr 2010 14:21:16 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Miller <davem@...emloft.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Johannes Weiner <hannes@...xchg.org>,
	linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org
Subject: Re: [PATCH 18/39] lmb: Add lmb_reserve_area_overlap_ok()

On Thu, 2010-04-08 at 23:03 -0700, Yinghai Lu wrote:
> Some areas from firmware could be reserved several times from different callers.
> 
> If these area are overlapped, We may have overlapped entries in lmb.reserved.
> 
> Try to free the area at first, before rerserve them again.
> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> ---

> +
> +/*
> + * Could be used to avoid having overlap entries in lmb.reserved.region.
> + *  Don't need to use it with area that is from lmb_find_area()
> + *  Only use it for the area that fw hidden area.
> + */
> +void __init lmb_reserve_area_overlap_ok(u64 start, u64 end, char *name)
> +{
> +	if (start == end)
> +		return;
> +
> +	if (WARN_ONCE(start > end, "lmb_reserve_area_overlap_ok: wrong range [%#llx, %#llx]\n", start, end))
> +		return;
> +
> +	/* Free that region at first */
> +	lmb_free(start, end - start);
> +	__lmb_reserve_area(start, end, name);
>  }

That is going to only work with one overlap. IE. lmb_free() will not do
very well unless it's a one and only match.

You should modify it to work in a loop.

Besides, lmb_reserve_area_overlap_ok() sucks as a name :-)

Cheers,
Ben.




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