Commit 405966ef authored by Danilo Krummrich's avatar Danilo Krummrich Committed by Miguel Ojeda
Browse files

rust: alloc: remove `VecExt` extension 



Now that all existing `Vec` users were moved to the kernel `Vec` type,
remove the `VecExt` extension.

Reviewed-by: default avatarAlice Ryhl <aliceryhl@google.com>
Reviewed-by: default avatarBenno Lossin <benno.lossin@proton.me>
Reviewed-by: default avatarGary Guo <gary@garyguo.net>
Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
Link: https://lore.kernel.org/r/20241004154149.93856-21-dakr@kernel.org


Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent 58eff8e8

rust/kernel/alloc.rs

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Original line number Diff line number Diff line
@@ -7,7 +7,6 @@ 
pub mod kbox;

pub mod kvec;

pub mod layout;

pub mod vec_ext;



#[cfg(any(test, testlib))]

pub mod allocator_test;

rust/kernel/alloc/vec_ext.rs

deleted100644 → 0
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Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0



//! Extensions to [`Vec`] for fallible allocations.



use super::{AllocError, Flags};

use alloc::vec::Vec;



/// Extensions to [`Vec`].

pub trait VecExt<T>: Sized {

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

    ///

    /// # Examples

    ///

    /// ```

    /// let v = Vec::<u32>::with_capacity(20, GFP_KERNEL)?;

    ///

    /// assert!(v.capacity() >= 20);

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

    /// ```

    fn with_capacity(capacity: usize, flags: Flags) -> Result<Self, AllocError>;



    /// Appends an element to the back of the [`Vec`] instance.

    ///

    /// # Examples

    ///

    /// ```

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

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

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

    ///

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

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

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

    /// ```

    fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError>;



    /// Pushes clones of the elements of slice into the [`Vec`] instance.

    ///

    /// # Examples

    ///

    /// ```

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

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

    ///

    /// v.extend_from_slice(&[20, 30, 40], GFP_KERNEL)?;

    /// assert_eq!(&v, &[1, 20, 30, 40]);

    ///

    /// v.extend_from_slice(&[50, 60], GFP_KERNEL)?;

    /// assert_eq!(&v, &[1, 20, 30, 40, 50, 60]);

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

    /// ```

    fn extend_from_slice(&mut self, other: &[T], flags: Flags) -> Result<(), AllocError>

    where

        T: Clone;



    /// Ensures that the capacity exceeds the length by at least `additional` elements.

    ///

    /// # Examples

    ///

    /// ```

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

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

    ///

    /// v.reserve(10, GFP_KERNEL)?;

    /// let cap = v.capacity();

    /// assert!(cap >= 10);

    ///

    /// v.reserve(10, GFP_KERNEL)?;

    /// let new_cap = v.capacity();

    /// assert_eq!(new_cap, cap);

    ///

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

    /// ```

    fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError>;

}



impl<T> VecExt<T> for Vec<T> {

    fn with_capacity(capacity: usize, flags: Flags) -> Result<Self, AllocError> {

        let mut v = Vec::new();

        <Self as VecExt<_>>::reserve(&mut v, capacity, flags)?;

        Ok(v)

    }



    fn push(&mut self, v: T, flags: Flags) -> Result<(), AllocError> {

        <Self as VecExt<_>>::reserve(self, 1, flags)?;

        let s = self.spare_capacity_mut();

        s[0].write(v);



        // SAFETY: We just initialised the first spare entry, so it is safe to increase the length

        // by 1. We also know that the new length is <= capacity because of the previous call to

        // `reserve` above.

        unsafe { self.set_len(self.len() + 1) };

        Ok(())

    }



    fn extend_from_slice(&mut self, other: &[T], flags: Flags) -> Result<(), AllocError>

    where

        T: Clone,

    {

        <Self as VecExt<_>>::reserve(self, other.len(), flags)?;

        for (slot, item) in core::iter::zip(self.spare_capacity_mut(), other) {

            slot.write(item.clone());

        }



        // SAFETY: We just initialised the `other.len()` spare entries, so it is safe to increase

        // the length by the same amount. We also know that the new length is <= capacity because

        // of the previous call to `reserve` above.

        unsafe { self.set_len(self.len() + other.len()) };

        Ok(())

    }



    #[cfg(any(test, testlib))]

    fn reserve(&mut self, additional: usize, _flags: Flags) -> Result<(), AllocError> {

        Vec::reserve(self, additional);

        Ok(())

    }



    #[cfg(not(any(test, testlib)))]

    fn reserve(&mut self, additional: usize, flags: Flags) -> Result<(), AllocError> {

        let len = self.len();

        let cap = self.capacity();



        if cap - len >= additional {

            return Ok(());

        }



        if core::mem::size_of::<T>() == 0 {

            // The capacity is already `usize::MAX` for SZTs, we can't go higher.

            return Err(AllocError);

        }



        // We know cap is <= `isize::MAX` because `Layout::array` fails if the resulting byte size

        // is greater than `isize::MAX`. So the multiplication by two won't overflow.

        let new_cap = core::cmp::max(cap * 2, len.checked_add(additional).ok_or(AllocError)?);

        let layout = core::alloc::Layout::array::<T>(new_cap).map_err(|_| AllocError)?;



        let (old_ptr, len, cap) = destructure(self);



        // We need to make sure that `ptr` is either NULL or comes from a previous call to

        // `krealloc_aligned`. A `Vec<T>`'s `ptr` value is not guaranteed to be NULL and might be

        // dangling after being created with `Vec::new`. Instead, we can rely on `Vec<T>`'s capacity

        // to be zero if no memory has been allocated yet.

        let ptr = if cap == 0 {

            core::ptr::null_mut()

        } else {

            old_ptr

        };



        // SAFETY: `ptr` is valid because it's either NULL or comes from a previous call to

        // `krealloc_aligned`. We also verified that the type is not a ZST.

        let new_ptr = unsafe { super::allocator::krealloc_aligned(ptr.cast(), layout, flags) };

        if new_ptr.is_null() {

            // SAFETY: We are just rebuilding the existing `Vec` with no changes.

            unsafe { rebuild(self, old_ptr, len, cap) };

            Err(AllocError)

        } else {

            // SAFETY: `ptr` has been reallocated with the layout for `new_cap` elements. New cap

            // is greater than `cap`, so it continues to be >= `len`.

            unsafe { rebuild(self, new_ptr.cast::<T>(), len, new_cap) };

            Ok(())

        }

    }

}



#[cfg(not(any(test, testlib)))]

fn destructure<T>(v: &mut Vec<T>) -> (*mut T, usize, usize) {

    let mut tmp = Vec::new();

    core::mem::swap(&mut tmp, v);

    let mut tmp = core::mem::ManuallyDrop::new(tmp);

    let len = tmp.len();

    let cap = tmp.capacity();

    (tmp.as_mut_ptr(), len, cap)

}



/// Rebuilds a `Vec` from a pointer, length, and capacity.

///

/// # Safety

///

/// The same as [`Vec::from_raw_parts`].

#[cfg(not(any(test, testlib)))]

unsafe fn rebuild<T>(v: &mut Vec<T>, ptr: *mut T, len: usize, cap: usize) {

    // SAFETY: The safety requirements from this function satisfy those of `from_raw_parts`.

    let mut tmp = unsafe { Vec::from_raw_parts(ptr, len, cap) };

    core::mem::swap(&mut tmp, v);

}

rust/kernel/prelude.rs

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Original line number Diff line number Diff line
@@ -14,10 +14,7 @@ 
#[doc(no_inline)]

pub use core::pin::Pin;



pub use crate::alloc::{flags::*, vec_ext::VecExt, Box, KBox, KVBox, KVVec, KVec, VBox, VVec};



#[doc(no_inline)]

pub use alloc::vec::Vec;

pub use crate::alloc::{flags::*, Box, KBox, KVBox, KVVec, KVec, VBox, VVec};



#[doc(no_inline)]

pub use macros::{module, pin_data, pinned_drop, vtable, Zeroable};