Commit 67161843 authored by Danilo Krummrich's avatar Danilo Krummrich
Browse files

rust: alloc: kbox: implement AsPageIter for VBox 



Implement AsPageIter for VBox; this allows to iterate and borrow the
backing pages of a VBox. This, for instance, is useful in combination
with VBox 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>
Link: https://lore.kernel.org/r/20250820145434.94745-6-dakr@kernel.org


Signed-off-by: default avatarDanilo Krummrich <dakr@kernel.org>
parent 866ec3ba

rust/kernel/alloc/kbox.rs

+39 −1
Original line number Diff line number Diff line
@@ -3,7 +3,7 @@ 
//! Implementation of [`Box`].



#[allow(unused_imports)] // Used in doc comments.

use super::allocator::{KVmalloc, Kmalloc, Vmalloc};

use super::allocator::{KVmalloc, Kmalloc, Vmalloc, VmallocPageIter};

use super::{AllocError, Allocator, Flags};

use core::alloc::Layout;

use core::borrow::{Borrow, BorrowMut};
@@ -18,6 +18,7 @@ 


use crate::ffi::c_void;

use crate::init::InPlaceInit;

use crate::page::AsPageIter;

use crate::types::ForeignOwnable;

use pin_init::{InPlaceWrite, Init, PinInit, ZeroableOption};
@@ -598,3 +599,40 @@ fn drop(&mut self) { 
        unsafe { A::free(self.0.cast(), layout) };

    }

}



/// # Examples

///

/// ```

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

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

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

///

/// let mut vbox = VBox::new((), GFP_KERNEL)?;

///

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

///

/// let mut vbox = VBox::<[u8; PAGE_SIZE]>::new_uninit(GFP_KERNEL)?;

///

/// let page = vbox.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 VBox<T> {

    type Iter<'a>

        = VmallocPageIter<'a>

    where

        T: 'a;



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

        let ptr = self.0.cast();

        let size = core::mem::size_of::<T>();



        // 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) }

    }

}