linux-kernel - Re: [PATCH V3 1/2] mm/memblock.c: trivial code refine in memblock_is_region

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Message-ID: <20161222090648.GB6048@dhcp22.suse.cz>
Date:   Thu, 22 Dec 2016 10:06:48 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Wei Yang <richard.weiyang@...il.com>
Cc:     trivial@...nel.org, akpm@...ux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3 1/2] mm/memblock.c: trivial code refine in
 memblock_is_region_memory()

On Wed 21-12-16 23:30:32, Wei Yang wrote:
> memblock_is_region_memory() invoke memblock_search() to see whether the
> base address is in the memory region. If it fails, idx would be -1. Then,
> it returns 0.
> 
> If the memblock_search() returns a valid index, it means the base address
> is guaranteed to be in the range memblock.memory.regions[idx]. Because of
> this, it is not necessary to check the base again.
> 
> This patch removes the check on "base".

OK, the patch looks correct. I doubt it makes any real difference but I
do not see it being harmful.

> Signed-off-by: Wei Yang <richard.weiyang@...il.com>

Acked-by: Michal Hocko <mhocko@...e.com>

> ---
>  mm/memblock.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 7608bc3..4929e06 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -1615,8 +1615,7 @@ int __init_memblock memblock_is_region_memory(phys_addr_t base, phys_addr_t size
>  
>  	if (idx == -1)
>  		return 0;
> -	return memblock.memory.regions[idx].base <= base &&
> -		(memblock.memory.regions[idx].base +
> +	return (memblock.memory.regions[idx].base +
>  		 memblock.memory.regions[idx].size) >= end;
>  }
>  
> -- 
> 2.5.0

-- 
Michal Hocko
SUSE Labs