linux-kernel - Re: [PATCH 5/5] rust: alloc: add Vec::retain

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Message-ID: <D8LFZZXODIR4.5XCGWBP93NNX@proton.me>
Date: Thu, 20 Mar 2025 22:21:56 +0000
From: Benno Lossin <benno.lossin@...ton.me>
To: Alice Ryhl <aliceryhl@...gle.com>, Danilo Krummrich <dakr@...nel.org>
Cc: rust-for-linux@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/5] rust: alloc: add Vec::retain

On Thu Mar 20, 2025 at 2:53 PM CET, Alice Ryhl wrote:
> diff --git a/rust/kernel/alloc/kvec.rs b/rust/kernel/alloc/kvec.rs
> index 303198509885f5e24b74da5a92382b518de3e1c0..00dabea8ea6c8a742a7fc95954d8de58be124493 100644
> --- a/rust/kernel/alloc/kvec.rs
> +++ b/rust/kernel/alloc/kvec.rs
> @@ -588,6 +588,20 @@ pub fn drain_all(&mut self) -> DrainAll<'_, T> {
>              elements: self.spare_capacity_mut()[..len].iter_mut(),
>          }
>      }
> +
> +    /// Removes all elements that don't match the provided closure.

Can you also add an example here? Otherwise the code looks good.

---
Cheers,
Benno

> +    pub fn retain(&mut self, mut f: impl FnMut(&mut T) -> bool) {
> +        let mut num_kept = 0;
> +        let mut next_to_check = 0;
> +        while let Some(to_check) = self.get_mut(next_to_check) {
> +            if f(to_check) {
> +                self.swap(num_kept, next_to_check);
> +                num_kept += 1;
> +            }
> +            next_to_check += 1;
> +        }
> +        self.truncate(num_kept);
> +    }
>  }
>  
>  impl<T: Clone, A: Allocator> Vec<T, A> {