linux-kernel - Re: [PATCH] mm: remove a redundant condition in the for loop

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Message-ID: <CA+PpKPnuWDZL_KgoBZhokhSA_9Ydh=xmhUc3sPufAyaJs4NtLQ@mail.gmail.com>
Date:   Tue, 20 Jun 2017 09:39:17 +0800
From:   Hao Lee <haolee.swjtu@...il.com>
To:     Rasmus Villemoes <linux@...musvillemoes.dk>
Cc:     Vlastimil Babka <vbabka@...e.cz>, akpm@...ux-foundation.org,
        mgorman@...hsingularity.net, mhocko@...e.com,
        Johannes Weiner <hannes@...xchg.org>, iamjoonsoo.kim@....com,
        minchan@...nel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: remove a redundant condition in the for loop

On Tue, Jun 20, 2017 at 3:05 AM, Rasmus Villemoes
<linux@...musvillemoes.dk> wrote:
> On Mon, Jun 19 2017, Vlastimil Babka <vbabka@...e.cz> wrote:
>
>> On 06/19/2017 03:54 PM, Hao Lee wrote:
>>> The variable current_order decreases from MAX_ORDER-1 to order, so the
>>> condition current_order <= MAX_ORDER-1 is always true.
>>>
>>> Signed-off-by: Hao Lee <haolee.swjtu@...il.com>
>>
>> Sounds right.
>>
>> Acked-by: Vlastimil Babka <vbabka@...e.cz>
>
> current_order and order are both unsigned, and if order==0,
> current_order >= order is always true, and we may decrement
> current_order past 0 making it UINT_MAX... A comment would be in order,
> though.

Thanks, I didn't notice unsigned subtraction. Sorry about that.