Re: [PATCH 1/2] rust: bitmap: add MAX_LEN and NO_ALLOC_MAX_LEN constants

[Danilo Krummrich <dakr@kernel.org>]

On 10/20/25 3:33 PM, Alice Ryhl wrote:
> To avoid hard-coding these values in drivers, define constants for them
> that drivers can reference.
> 
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>

Yes, please! :)

Acked-by: Danilo Krummrich <dakr@kernel.org>

> @@ -238,11 +244,11 @@ pub fn new(nbits: usize, flags: Flags) -> Result<Self, AllocError> {
>                  nbits,
>              });
>          }
> -        if nbits > i32::MAX.try_into().unwrap() {
> +        if nbits > Self::MAX_LEN {
>              return Err(AllocError);
>          }
>          let nbits_u32 = u32::try_from(nbits).unwrap();

Can we also get rid of this please? :)

> -        // SAFETY: `BITS_PER_LONG < nbits` and `nbits <= i32::MAX`.
> +        // SAFETY: `BITS_PER_LONG < nbits` and `nbits <= MAX_LEN`.
>          let ptr = unsafe { bindings::bitmap_zalloc(nbits_u32, flags.as_raw()) };
>          let ptr = NonNull::new(ptr).ok_or(AllocError)?;
>          // INVARIANT: `ptr` returned by C `bitmap_zalloc` and `nbits` checked.