Commit a654a6e0 authored by Danilo Krummrich's avatar Danilo Krummrich Committed by Miguel Ojeda
Browse files

rust: alloc: separate `aligned_size` from `krealloc_aligned` 



Separate `aligned_size` from `krealloc_aligned`.

Subsequent patches implement `Allocator` derivates, such as `Kmalloc`,
that require `aligned_size` and replace the original `krealloc_aligned`.

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/20241004154149.93856-3-dakr@kernel.org


Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent b7a084ba

rust/kernel/alloc/allocator.rs

+12 −7
Original line number Diff line number Diff line
@@ -8,6 +8,17 @@ 


struct KernelAllocator;



/// Returns a proper size to alloc a new object aligned to `new_layout`'s alignment.

fn aligned_size(new_layout: Layout) -> usize {

    // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.

    let layout = new_layout.pad_to_align();



    // Note that `layout.size()` (after padding) is guaranteed to be a multiple of `layout.align()`

    // which together with the slab guarantees means the `krealloc` will return a properly aligned

    // object (see comments in `kmalloc()` for more information).

    layout.size()

}



/// Calls `krealloc` with a proper size to alloc a new object aligned to `new_layout`'s alignment.

///

/// # Safety
@@ -15,13 +26,7 @@ 
/// - `ptr` can be either null or a pointer which has been allocated by this allocator.

/// - `new_layout` must have a non-zero size.

pub(crate) unsafe fn krealloc_aligned(ptr: *mut u8, new_layout: Layout, flags: Flags) -> *mut u8 {

    // Customized layouts from `Layout::from_size_align()` can have size < align, so pad first.

    let layout = new_layout.pad_to_align();



    // Note that `layout.size()` (after padding) is guaranteed to be a multiple of `layout.align()`

    // which together with the slab guarantees means the `krealloc` will return a properly aligned

    // object (see comments in `kmalloc()` for more information).

    let size = layout.size();

    let size = aligned_size(new_layout);



    // SAFETY:

    // - `ptr` is either null or a pointer returned from a previous `k{re}alloc()` by the