linux-kernel - Re: [PATCH] lib/genalloc.c: fix the end addr check in addr_in_gen

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Date:	Mon, 22 Dec 2014 13:05:39 -0800
From:	Andrew Morton <akpm@...ux-foundation.org>
To:	Toshi Kikuchi <toshik@...omium.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] lib/genalloc.c: fix the end addr check in
 addr_in_gen_pool()

On Thu, 18 Dec 2014 18:30:59 -0800 Toshi Kikuchi <toshik@...omium.org> wrote:

> Since chunk->end_addr is (chunk->start_addr + size - 1),
> the end address to compare should be (start + size - 1).
> 
> Signed-off-by: Toshi Kikuchi <toshik@...omium.org>
> ---
>  lib/genalloc.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/genalloc.c b/lib/genalloc.c
> index 2e65d20..42a95e9 100644
> --- a/lib/genalloc.c
> +++ b/lib/genalloc.c
> @@ -415,7 +415,7 @@ bool addr_in_gen_pool(struct gen_pool *pool, unsigned long start,
>  			size_t size)
>  {
>  	bool found = false;
> -	unsigned long end = start + size;
> +	unsigned long end = start + size - 1;
>  	struct gen_pool_chunk *chunk;
>  
>  	rcu_read_lock();

urgh.  gen_pool_chunk.end_addr should have been made exclusive, not
inclusive.  Or switch to start_addr/size.  The code would be
considerably nicer that way.

And the struct gen_pool_chunk definition should be moved into
genalloc.c.  I'm not sure what drivers/acpi/apei/ghes.c is doing
fiddling around with genalloc internals, but it should stop doing it.

Sigh :(
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