[PATCH 2/2] bitfield: Ensure the return value of type##_replace_bits() is checked

[Yury Norov]

Hi Ben,

On Thu, Jul 03, 2025 at 02:57:29PM +0100, Ben Horgan wrote:
> As type##_replace_bits() has no side effects it is only useful if its
> return value is checked. Add __must_check to enforce this usage. To have
> the bits replaced in-place typep##_replace_bits() can be used instead.
> 
> Signed-off-by: Ben Horgan <ben.horgan at arm.com>
> ---
>  include/linux/bitfield.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/bitfield.h b/include/linux/bitfield.h
> index 6d9a53db54b6..39333b80d22b 100644
> --- a/include/linux/bitfield.h
> +++ b/include/linux/bitfield.h
> @@ -195,8 +195,8 @@ static __always_inline __##type type##_encode_bits(base v, base field)	\
>  		__field_overflow();					\
>  	return to((v & field_mask(field)) * field_multiplier(field));	\
>  }									\
> -static __always_inline __##type type##_replace_bits(__##type old,	\
> -					base val, base field)		\
> +static __always_inline __##type __must_check type##_replace_bits(__##type old,	\
> +							base val, base field)	\
>  {									\
>  	return (old & ~to(field)) | type##_encode_bits(val, field);	\
>  }									\

So, would it make sense to mark _encode_bits() and _get_bits() as
__must_check as well? At least from the point of unification, it
would.

How would we move this - with my bitmap-for next or with arm branch?

Thanks,
Yury