Re: [PATCH v4 05/28] rust: alloc: add module `allocator_test`

Benno Lossin
2024-08-06T16:54:18Z

On 05.08.24 17:19, Danilo Krummrich wrote:
> `Allocator`s, such as `Kmalloc`, will be used by e.g. `Box` and `Vec` in
> subsequent patches, and hence this dependency propagates throughout the
> whole kernel.
>
> Add the `allocator_test` module that provides an empty implementation
> for all `Allocator`s in the kernel, such that we don't break the
> `rusttest` make target in subsequent patches.

This is confusing, since you are talking about both our new `Allocator`
trait, allocators and the `alloc` crate `Allocator`.

> Reviewed-by: Alice Ryhl <aliceryhl@google.com>
> Signed-off-by: Danilo Krummrich <dakr@kernel.org>
> ---
> rust/kernel/alloc.rs | 9 +++++++--
> rust/kernel/alloc/allocator_test.rs | 19 +++++++++++++++++++
> 2 files changed, 26 insertions(+), 2 deletions(-)
> create mode 100644 rust/kernel/alloc/allocator_test.rs
>
> diff --git a/rust/kernel/alloc.rs b/rust/kernel/alloc.rs
> index bc01a17df5e0..942e2755f217 100644
> --- a/rust/kernel/alloc.rs
> +++ b/rust/kernel/alloc.rs
> @@ -2,12 +2,17 @@
>
> //! Extensions to the [`alloc`] crate.
>
> -#[cfg(not(test))]
> -#[cfg(not(testlib))]
> +#[cfg(not(any(test, testlib)))]
> pub mod allocator;
> pub mod box_ext;
> pub mod vec_ext;
>
> +#[cfg(any(test, testlib))]
> +pub mod allocator_test;
> +
> +#[cfg(any(test, testlib))]
> +pub use self::allocator_test as allocator;
> +
> /// Indicates an allocation error.
> #[derive(Copy, Clone, PartialEq, Eq, Debug)]
> pub struct AllocError;
> diff --git a/rust/kernel/alloc/allocator_test.rs b/rust/kernel/alloc/allocator_test.rs
> new file mode 100644
> index 000000000000..4785efc474a7
> --- /dev/null
> +++ b/rust/kernel/alloc/allocator_test.rs
> @@ -0,0 +1,19 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#![allow(missing_docs)]
> +
> +use super::{AllocError, Allocator, Flags};
> +use core::alloc::Layout;
> +use core::ptr::NonNull;
> +
> +pub struct Kmalloc;
> +
> +unsafe impl Allocator for Kmalloc {
> + unsafe fn realloc(
> + _ptr: Option<NonNull<u8>>,
> + _layout: Layout,
> + _flags: Flags,
> + ) -> Result<NonNull<[u8]>, AllocError> {
> + panic!();

Does `build_error!()` also work? If yes, then I would prefer that.

---
Cheers,
Benno

> + }
> +}
> --
> 2.45.2
>