linux-kernel - Re: [PATCH 6/9] nilfs2: fix out-of-range warning

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Date: Thu, 28 Mar 2024 15:04:49 -0700
From: Justin Stitt <justinstitt@...gle.com>
To: Arnd Bergmann <arnd@...nel.org>
Cc: linux-kernel@...r.kernel.org, Ryusuke Konishi <konishi.ryusuke@...il.com>, 
	Nathan Chancellor <nathan@...nel.org>, Arnd Bergmann <arnd@...db.de>, 
	Nick Desaulniers <ndesaulniers@...gle.com>, Bill Wendling <morbo@...gle.com>, 
	Andrew Morton <akpm@...ux-foundation.org>, Philipp Stanner <pstanner@...hat.com>, 
	Christian Brauner <brauner@...nel.org>, Jeff Layton <jlayton@...nel.org>, 
	Thorsten Blum <thorsten.blum@...lux.com>, linux-nilfs@...r.kernel.org, 
	llvm@...ts.linux.dev
Subject: Re: [PATCH 6/9] nilfs2: fix out-of-range warning

On Thu, Mar 28, 2024 at 7:32 AM Arnd Bergmann <arnd@...nel.org> wrote:
>
> From: Arnd Bergmann <arnd@...db.de>
>
> clang-14 points out that v_size is always smaller than a 64KB
> page size if that is configured by the CPU architecture:

Is this only with clang-14?

>
> fs/nilfs2/ioctl.c:63:19: error: result of comparison of constant 65536 with expression of type '__u16' (aka 'unsigned short') is always false [-Werror,-Wtautological-constant-out-of-range-compare]
>         if (argv->v_size > PAGE_SIZE)
>             ~~~~~~~~~~~~ ^ ~~~~~~~~~
>
> This is ok, so just shut up that warning with a cast.
>
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

My question out of curiosity aside,

Reviewed-by: Justin Stitt <justinstitt@...gle.com>

> ---
>  fs/nilfs2/ioctl.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/nilfs2/ioctl.c b/fs/nilfs2/ioctl.c
> index f1a01c191cf5..8be471ce4f19 100644
> --- a/fs/nilfs2/ioctl.c
> +++ b/fs/nilfs2/ioctl.c
> @@ -60,7 +60,7 @@ static int nilfs_ioctl_wrap_copy(struct the_nilfs *nilfs,
>         if (argv->v_nmembs == 0)
>                 return 0;
>
> -       if (argv->v_size > PAGE_SIZE)
> +       if ((size_t)argv->v_size > PAGE_SIZE)
>                 return -EINVAL;
>
>         /*
> --
> 2.39.2
>