Commit f2b4dd70 authored by Alice Ryhl's avatar Alice Ryhl Committed by Danilo Krummrich
Browse files

rust: alloc: add Vec::pop 



This introduces a basic method that our custom Vec is missing. I expect
that it will be used in many places, but at the time of writing, Rust
Binder has six calls to Vec::pop.

Signed-off-by: default avatarAlice Ryhl <aliceryhl@google.com>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: default avatarBenno Lossin <lossin@kernel.org>
Link: https://lore.kernel.org/r/20250502-vec-methods-v5-2-06d20ad9366f@google.com


Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
parent a1e4d5c9

rust/kernel/alloc/kvec.rs

+31 −0
Original line number Diff line number Diff line
@@ -320,6 +320,37 @@ pub fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> { 
        Ok(())

    }



    /// Removes the last element from a vector and returns it, or `None` if it is empty.

    ///

    /// # Examples

    ///

    /// ```

    /// let mut v = KVec::new();

    /// v.push(1, GFP_KERNEL)?;

    /// v.push(2, GFP_KERNEL)?;

    /// assert_eq!(&v, &[1, 2]);

    ///

    /// assert_eq!(v.pop(), Some(2));

    /// assert_eq!(v.pop(), Some(1));

    /// assert_eq!(v.pop(), None);

    /// # Ok::<(), Error>(())

    /// ```

    pub fn pop(&mut self) -> Option<T> {

        if self.is_empty() {

            return None;

        }



        let removed: *mut T = {

            // SAFETY: We just checked that the length is at least one.

            let slice = unsafe { self.dec_len(1) };

            // SAFETY: The argument to `dec_len` was 1 so this returns a slice of length 1.

            unsafe { slice.get_unchecked_mut(0) }

        };



        // SAFETY: The guarantees of `dec_len` allow us to take ownership of this value.

        Some(unsafe { removed.read() })

    }



    /// Creates a new [`Vec`] instance with at least the given capacity.

    ///

    /// # Examples