Re: [PATCH 1/3] bitmap: generalize node_random()

[Andrew Morton <akpm@linux-foundation.org>]

On Wed,  4 Jun 2025 17:21:21 -0400 Yury Norov <yury.norov@gmail.com> wrote:

> Generalize node_random and make it available to general bitmaps and
> cpumasks users.

Seems sensible.

> --- a/lib/find_bit.c
> +++ b/lib/find_bit.c
>  
> +unsigned long find_random_bit(const unsigned long *addr, unsigned long size)
> +{
> +	int w = bitmap_weight(addr, size);
> +
> +	switch (w) {
> +	case 0:
> +		return size;
> +	case 1:
> +		return find_first_bit(addr, size);

Is the `1' special case useful?  The `default' case should still work OK?

> +	default:
> +		return find_nth_bit(addr, size, get_random_u32_below(w));
> +	}
> +}
> +EXPORT_SYMBOL(find_random_bit);

Some kerneldoc, please?

Of course, the hard-coding of get_random_u32_below() might be
unsuitable for some future potential callers but we can deal with that
if it ever occurs.