linux-kernel - Re: [PATCH 15/22] lmb: Add lmb_reserve_area_overlap

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Date:	Mon, 10 May 2010 16:34:41 +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 15/22] lmb: Add lmb_reserve_area_overlap_ok()

On Sat, 2010-05-08 at 08:17 -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.

I explained earlier that name sucked :-)

We just need to make lmb_reserve() capable of dealing with overlaps
instead. I like the idea of implementing that with a free.

Cheers,
Ben.

> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> ---
>  include/linux/lmb.h |    1 +
>  mm/lmb.c            |   27 +++++++++++++++++++++++++--
>  2 files changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/lmb.h b/include/linux/lmb.h
> index 90022c1..47b9d7f 100644
> --- a/include/linux/lmb.h
> +++ b/include/linux/lmb.h
> @@ -87,6 +87,7 @@ lmb_end_pfn(struct lmb_region *type, unsigned long region_nr)
>  }
>  
>  void lmb_reserve_area(u64 start, u64 end, char *name);
> +void lmb_reserve_area_overlap_ok(u64 start, u64 end, char *name);
>  void lmb_free_area(u64 start, u64 end);
>  void lmb_add_memory(u64 start, u64 end);
>  u64 __lmb_find_area(u64 ei_start, u64 ei_last, u64 start, u64 end,
> diff --git a/mm/lmb.c b/mm/lmb.c
> index 2870dd9..decea60 100644
> --- a/mm/lmb.c
> +++ b/mm/lmb.c
> @@ -605,6 +605,12 @@ void __init lmb_add_memory(u64 start, u64 end)
>  	__check_and_double_region_array(&lmb.memory, &lmb_memory_region[0]);
>  }
>  
> +static void __init __lmb_reserve_area(u64 start, u64 end, char *name)
> +{
> +	lmb_add_region(&lmb.reserved, start, end - start);
> +	__check_and_double_region_array(&lmb.reserved, &lmb_reserved_region[0]);
> +}
> +
>  void __init lmb_reserve_area(u64 start, u64 end, char *name)
>  {
>  	if (start == end)
> @@ -613,8 +619,25 @@ void __init lmb_reserve_area(u64 start, u64 end, char *name)
>  	if (WARN_ONCE(start > end, "lmb_reserve_area: wrong range [%#llx, %#llx]\n", start, end))
>  		return;
>  
> -	lmb_add_region(&lmb.reserved, start, end - start);
> -	__check_and_double_region_array(&lmb.reserved, &lmb_reserved_region[0]);
> +	__lmb_reserve_area(start, end, name);
> +}
> +
> +/*
> + * 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);
>  }
>  
>  void __init lmb_free_area(u64 start, u64 end)


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