Re: [PATCH 2/3] rust: alloc: add Vec::resize method

[Danilo Krummrich <dakr@kernel.org>]

On Fri, Mar 14, 2025 at 09:42:34PM -0500, Andrew Ballance wrote:
> implemnts the equivalent of the rust std's Vec::resize
> on the kernel's Vec type.

Nit: It is preferred to use the imperative form, i.e. "Implement the equivalent
[...]".

> 
> Signed-off-by: Andrew Ballance <andrewjballance@gmail.com>
> ---
>  rust/kernel/alloc/kvec.rs | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs
> index 75e9feebb81f..cbfef2e56f9c 100644
> --- a/rust/kernel/alloc/kvec.rs
> +++ b/rust/kernel/alloc/kvec.rs
> @@ -554,6 +554,31 @@ pub fn from_elem(value: T, n: usize, flags: Flags) -> Result<Self, AllocError> {
>  
>          Ok(v)
>      }
> +
> +    /// Resizes the [`Vec`] so that `len` is equal to `new_len`.
> +    ///
> +    /// If `new_len` is smaller than `len`, the `Vec` is [`Vec::truncate`]d.
> +    /// If `new_len` is larger, each new slot is filled with clones of `value`.
> +    ///
> +    /// # Example

Nit: Please add an empty line after the heading.

> +    /// ```
> +    /// let mut v = kernel::kvec![1, 2, 3]?;
> +    /// v.resize(1, 42, GFP_KERNEL)?;
> +    /// assert_eq!(&v, &[1]);
> +    ///
> +    /// v.resize(3, 42, GFP_KERNEL)?;
> +    /// assert_eq!(&v, &[1, 42, 42]);
> +    ///
> +    /// # Ok::<(), Error>(())
> +    /// ```
> +    pub fn resize(&mut self, new_len: usize, value: T, flags: Flags) -> Result<(), AllocError> {
> +        if new_len > self.len() {
> +            self.extend_with(new_len - self.len(), value, flags)
> +        } else {
> +            self.truncate(new_len);
> +            Ok(())
> +        }
> +    }
>  }
>  
>  impl<T, A> Drop for Vec<T, A>
> -- 
> 2.48.1
>