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Date:   Tue, 1 Feb 2022 16:32:27 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     =?iso-8859-1?Q?Ma=EDra?= Canal <maira.canal@usp.br>
Cc:     gregkh@linuxfoundation.org, tj@kernel.org, nathan@kernel.org,
        ndesaulniers@google.com, willy@infradead.org,
        linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        llvm@lists.linux.dev
Subject: Re: [PATCH v3] seq_file: fix NULL pointer arithmetic warning
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On Mon, Jan 31, 2022 at 03:22:42PM -0300, Ma?ra Canal wrote:
> Implement conditional logic in order to replace NULL pointer arithmetic.
> 
> The use of NULL pointer arithmetic was pointed out by clang with the
> following warning:
> 
> fs/kernfs/file.c:128:15: warning: performing pointer arithmetic on a
> null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>                 return NULL + !*ppos;
>                        ~~~~ ^
> fs/seq_file.c:559:14: warning: performing pointer arithmetic on a
> null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>         return NULL + (*pos == 0);
> 
> Signed-off-by: Ma?ra Canal <maira.canal@usp.br>
> ---
> V1 -> V2:
> - Use SEQ_START_TOKEN instead of open-coding it
> - kernfs_seq_start call single_start instead of open-coding it
> V2 -> V3:
> - Remove the EXPORT of the single_start symbol

Applied.