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

Philipp Stanner
2024-03-28T15:21:44Z

On Thu, 2024-03-28 at 15:30 +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@arndb.de>
>
> clang-14 points out that v_size is always smaller than a 64KB
> page size if that is configured by the CPU architecture:
>
> 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.

nit:
It's not a warning, but actually a compile error, right?

(no idea why they make that an error btw. Warning would be perfectly
fine)

>
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Should / could that be backported to stable kernels in case people
start building those with clang-14?

Regards,
P.

> ---
>  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;
>
>         /*