linux-kernel - Re: linux-6.3-rc6/lib/maple

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Message-ID: <cd5b6ce1-3c2f-97f5-64c5-4c4c90c40627@bytedance.com>
Date:   Mon, 10 Apr 2023 16:23:42 +0800
From:   Peng Zhang <zhangpeng.00@...edance.com>
To:     David Binderman <dcb314@...mail.com>
Cc:     "Liam.Howlett@...cle.com" <Liam.Howlett@...cle.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        maple-tree@...ts.infradead.org
Subject: Re: linux-6.3-rc6/lib/maple_tree.c: Two style issues


在 2023/4/10 15:05, David Binderman 写道:
> Hello there,
>
> Static analyser cppcheck says:
>
> 1.
>
> linux-6.3-rc6/lib/maple_tree.c:1951:21: style: Array index 'split' is used before limits check. [arrayIndexThenCheck]
>
> Source code is
>
>          while (((bn->pivot[split] - min) < slot_count - 1) &&
>                 (split < slot_count - 1) && (b_end - split > slot_min))
>
> Suggest move limits check to before use.

Hi,

It should be fine here. The upper bound of split is b_end.
The initial state (split = b_end / 2) must not cross the boundary,
and (b_end - split > slot_min) ensures that it will not cross the 
boundary in the future.

>
> 2.
>
> linux-6.3-rc6/lib/maple_tree.c:3289:11: warning: Size of pointer 'pivs' used instead of size of its data. [pointerSize]
>
> Source code is
>
>             memset(pivs + tmp, 0,
>                     sizeof(unsigned long *) * (max_p - tmp));

It's not good here, I can fix it.

Thanks.

>
> but
>
>      unsigned long *l_pivs, *pivs, gap;
>
> Pointers and long don't have to be the same size. Suggest code rework.
>
> Regards
>
> David Binderman
>