Re: [PATCH v17 02/10] rust: types: Add Ownable/Owned types
From: Alice Ryhl <aliceryhl@google.com>
Date: 2026-06-16 11:54:39
Also in:
dri-devel, driver-core, linux-block, linux-fsdevel, linux-mm, linux-pci, linux-pm, lkml, rust-for-linux
On Thu, Jun 04, 2026 at 10:11:14PM +0200, Andreas Hindborg wrote:
From: Asahi Lina <redacted> By analogy to `AlwaysRefCounted` and `ARef`, an `Ownable` type is a (typically C FFI) type that *may* be owned by Rust, but need not be. Unlike `AlwaysRefCounted`, this mechanism expects the reference to be unique within Rust, and does not allow cloning. Conceptually, this is similar to a `KBox<T>`, except that it delegates resource management to the `T` instead of using a generic allocator. [ om: - Split code into separate file and `pub use` it from types.rs. - Make from_raw() and into_raw() public. - Remove OwnableMut, and make DerefMut dependent on Unpin instead. - Usage example/doctest for Ownable/Owned. - Fixes to documentation and commit message. ] Link: https://lore.kernel.org/all/20250202-rust-page-v1-1-e3170d7fe55e@asahilina.net/ (local) Signed-off-by: Asahi Lina <redacted> Co-developed-by: Oliver Mangold <redacted> Signed-off-by: Oliver Mangold <redacted> Reviewed-by: Boqun Feng <redacted> Reviewed-by: Daniel Almeida <daniel.almeida@collabora.com> [ Andreas: Updated documentation, examples, and formatting. Change safety requirements, safety comments. Use a reference for `release`. ] Reviewed-by: Gary Guo <gary@garyguo.net> Co-developed-by: Andreas Hindborg <a.hindborg@kernel.org> Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
Overall looks good to me, but two nits below. With them fixed: Reviewed-by: Alice Ryhl <aliceryhl@google.com>
+pub trait Ownable {
+ /// Tear down this `Ownable`.
+ ///
+ /// Implementers of `Ownable` can use this function to clean up the use of `Self`. This can
+ /// include freeing the underlying object.
+ ///
+ /// # Safety
+ ///
+ /// Callers must ensure that the caller has exclusive ownership of `T`, and this ownership can
+ /// be transferred to the `release` method.
+ unsafe fn release(&mut self);I'd make this take a raw pointer because the pointer can be freed during the execution of release(), which references don't allow.
quoted hunk ↗ jump to hunk
diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs index 4329d3c2c2e5..4aec7b699269 100644 --- a/rust/kernel/types.rs +++ b/rust/kernel/types.rs@@ -11,6 +11,17 @@ }; use pin_init::{PinInit, Wrapper, Zeroable}; +pub use crate::{ + owned::{ + Ownable, + Owned, // + }, + sync::aref::{ + ARef, + AlwaysRefCounted, // + }, // +};
We removed the types::ARef re-export, so you shouldn't add it back. Alice