Commit 779db373 authored by Danilo Krummrich's avatar Danilo Krummrich
Browse files

rust: alloc: kvec: implement AsPageIter for VVec 



Implement AsPageIter for VVec; this allows to iterate and borrow the
backing pages of a VVec. This, for instance, is useful in combination
with VVec backing a scatterlist.

Reviewed-by: default avatarAlice Ryhl <aliceryhl@google.com>
Reviewed-by: default avatarAlexandre Courbot <acourbot@nvidia.com>
Tested-by: default avatarAlexandre Courbot <acourbot@nvidia.com>
Reviewed-by: default avatarDaniel Almeida <daniel.almeida@collabora.com>
Link: https://lore.kernel.org/r/20250820145434.94745-8-dakr@kernel.org


Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
parent 9acb4e63

rust/kernel/alloc/kvec.rs

+39 −1
Original line number Diff line number Diff line
@@ -3,10 +3,11 @@ 
//! Implementation of [`Vec`].



use super::{

    allocator::{KVmalloc, Kmalloc, Vmalloc},

    allocator::{KVmalloc, Kmalloc, Vmalloc, VmallocPageIter},

    layout::ArrayLayout,

    AllocError, Allocator, Box, Flags,

};

use crate::page::AsPageIter;

use core::{

    borrow::{Borrow, BorrowMut},

    fmt,
@@ -1017,6 +1018,43 @@ fn into_iter(self) -> Self::IntoIter { 
    }

}



/// # Examples

///

/// ```

/// # use kernel::prelude::*;

/// use kernel::alloc::allocator::VmallocPageIter;

/// use kernel::page::{AsPageIter, PAGE_SIZE};

///

/// let mut vec = VVec::<u8>::new();

///

/// assert!(vec.page_iter().next().is_none());

///

/// vec.reserve(PAGE_SIZE, GFP_KERNEL)?;

///

/// let page = vec.page_iter().next().expect("At least one page should be available.\n");

///

/// // SAFETY: There is no concurrent read or write to the same page.

/// unsafe { page.fill_zero_raw(0, PAGE_SIZE)? };

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

/// ```

impl<T> AsPageIter for VVec<T> {

    type Iter<'a>

        = VmallocPageIter<'a>

    where

        T: 'a;



    fn page_iter(&mut self) -> Self::Iter<'_> {

        let ptr = self.ptr.cast();

        let size = self.layout.size();



        // SAFETY:

        // - `ptr` is a valid pointer to the beginning of a `Vmalloc` allocation.

        // - `ptr` is guaranteed to be valid for the lifetime of `'a`.

        // - `size` is the size of the `Vmalloc` allocation `ptr` points to.

        unsafe { VmallocPageIter::new(ptr, size) }

    }

}



/// An [`Iterator`] implementation for [`Vec`] that moves elements out of a vector.

///

/// This structure is created by the [`Vec::into_iter`] method on [`Vec`] (provided by the