Re: [PATCH 33/38] mm/memblock.c: remove invalid check

From	Andrew Morton <akpm@linux-foundation.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH 33/38] mm/memblock.c: remove invalid check
Date	2015-09-21 23:40 +0200
Message-ID	<qbgYy-1Xv-13@gated-at.bofh.it> (permalink)
References	<qb9u2-83M-3@gated-at.bofh.it> <qb9DK-8gq-57@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Mon, 21 Sep 2015 15:34:05 +0200 Andrzej Hajda <a.hajda@samsung.com> wrote:

> Unsigned value cannot be lesser than zero.
> 
> The problem has been detected using proposed semantic patch
> scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci [1].
> 
> [1]: http://permalink.gmane.org/gmane.linux.kernel/2038576
> 
> ...
>
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -837,7 +837,7 @@ void __init_memblock __next_reserved_mem_region(u64 *idx,
>  {
>  	struct memblock_type *type = &memblock.reserved;
>  
> -	if (*idx >= 0 && *idx < type->cnt) {
> +	if (*idx < type->cnt) {

Linus has in the past expressed a preference for retaining checks such
as this.  iirc he finds it clearer.  And perhaps safer if the type
should change in the future.


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[PATCH 33/38] mm/memblock.c: remove invalid check Andrzej Hajda <a.hajda@samsung.com> - 2015-09-21 15:50 +0200
  Re: [PATCH 33/38] mm/memblock.c: remove invalid check Andrew Morton <akpm@linux-foundation.org> - 2015-09-21 23:40 +0200

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