Re: [PATCH v2 2/5] bitmap: Silence a clang -Wshorten-64-to-32 warning

[Yury Norov <yury.norov@gmail.com>]

Hi Ian,

On Wed, Apr 30, 2025 at 10:15:31AM -0700, Ian Rogers wrote:
> The clang warning -Wshorten-64-to-32 can be useful to catch
> inadvertent truncation. In some instances this truncation can lead to
> changing the sign of a result, for example, truncation to return an
> int to fit a sort routine. Silence the warning by making the implicit
> truncation explicit. This isn't to say the code is currently incorrect
> but without silencing the warning it is hard to spot the erroneous
> cases.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
>  include/linux/bitmap.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
> index 595217b7a6e7..4395e0a618f4 100644
> --- a/include/linux/bitmap.h
> +++ b/include/linux/bitmap.h
> @@ -442,7 +442,7 @@ static __always_inline
>  unsigned int bitmap_weight(const unsigned long *src, unsigned int nbits)
>  {
>  	if (small_const_nbits(nbits))
> -		return hweight_long(*src & BITMAP_LAST_WORD_MASK(nbits));
> +		return (int)hweight_long(*src & BITMAP_LAST_WORD_MASK(nbits));

This should return unsigned int, I guess?

Also, most of the functions you touch here have their copies in tools.
Can you please keep them synchronized?

Thanks,
Yury

>  	return __bitmap_weight(src, nbits);
>  }
>  
> -- 
> 2.49.0.906.g1f30a19c02-goog