Re: [PATCH v3] rust: bitmap: document panics in `next_bit` and `next_zero_bit`

[Georgios Androutsopoulos]

On Tue, Sep 8, 2026 at 4:13 PM Georgios Androutsopoulos
<georgeandrout13@xxxxxxxxx> wrote:
>
> `next_bit()` and `next_zero_bit()` use `bitmap_assert!()` to check
> that `start` is less than `self.len()`, which panics when
> `CONFIG_RUST_BITMAP_HARDENED` is enabled. However, neither function
> has a `# Panics` section, and both document that `None` is returned
> for exactly the input that triggers the panic.
>
> Update the documentation of `next_bit()` and `next_zero_bit()` to add
> the missing `# Panics` sections, add the missing blank doc comment line
> before `Returns` in `next_zero_bit()`, and simplify the wording.
>
> Fixes: 11eca92a2cae ("rust: add bitmap API.")
> Closes: https://github.com/Rust-for-Linux/linux/issues/1252
> Reviewed-by: Alexandre Courbot <acourbot@xxxxxxxxxx>
> Signed-off-by: Georgios Androutsopoulos <georgeandrout13@xxxxxxxxx>
> ---
> Changes in v3:
> - Use Closes: instead of Link:, and add Fixes:, following feedback from
>   Alexandre Courbot and Miguel Ojeda.
> - Link to v2: https://lore.kernel.org/rust-for-linux/20260828133543.2259029-1-georgeandrout13@xxxxxxxxx/
>
> Changes in v2:
> - Simplify doc wording following feedback from Alice Ryhl.
> - Remove extra empty line between Link: and Signed-off-by:.
> - Link to v1: https://lore.kernel.org/rust-for-linux/20260827150719.109145-1-georgeandrout13@xxxxxxxxx/
> ---
>  rust/kernel/bitmap.rs | 17 +++++++++++++++--
>  1 file changed, 15 insertions(+), 2 deletions(-)
>
> diff --git a/rust/kernel/bitmap.rs b/rust/kernel/bitmap.rs
> index b27e0ec80d64..b51c8a96f1a8 100644
> --- a/rust/kernel/bitmap.rs
> +++ b/rust/kernel/bitmap.rs
> @@ -459,7 +459,13 @@ pub fn last_bit(&self) -> Option<usize> {
>
>      /// Finds next set bit, starting from `start`.
>      ///
> -    /// Returns `None` if `start` is greater or equal to `self.nbits`.
> +    /// Returns `None` if no bits are set on or after the given index. The
> +    /// index `start` must be in bounds.
> +    ///
> +    /// # Panics
> +    ///
> +    /// Panics if `CONFIG_RUST_BITMAP_HARDENED` is enabled and `start` is
> +    /// out of bounds.
>      #[inline]
>      pub fn next_bit(&self, start: usize) -> Option<usize> {
>          bitmap_assert!(
> @@ -479,7 +485,14 @@ pub fn next_bit(&self, start: usize) -> Option<usize> {
>      }
>
>      /// Finds next zero bit, starting from `start`.
> -    /// Returns `None` if `start` is greater than or equal to `self.len()`.
> +    ///
> +    /// Returns `None` if no bits are zero on or after the given index. The
> +    /// index `start` must be in bounds.
> +    ///
> +    /// # Panics
> +    ///
> +    /// Panics if `CONFIG_RUST_BITMAP_HARDENED` is enabled and `start` is
> +    /// out of bounds.
>      #[inline]
>      pub fn next_zero_bit(&self, start: usize) -> Option<usize> {
>          bitmap_assert!(
>
> base-commit: 73e3f0710014fe6d4ed98cfc02292f6121db7558
> --
> 2.47.3
>

Hi,

Just checking if there are any remaining concerns with this patch, or if
it can be picked up.

Thanks,
Georgios