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AFNElJ8e2g+XsShcJ06wDJ717yokX3o8JL+uRnSlk69DApaKNV3Z/WCoLS0ZW32GcU6+kU5EGTGqgniiJA==@kvack.org X-Gm-Message-State: AOJu0Yx0bYo/iPz1/Je37XhRmP7DNOoVOxzzN0CDZIHIovOaLBtQ+0PB ZfzkT/g9bvsJSZWWJRcos0jbqP/C8FqFBg0ylDUhrTJ5vK+wGTXVa7KutRxt/B0Hne48mjLMdZ9 22mLgbBo1sYK1wY75Xg== X-Received: from edrc26.prod.google.com ([2002:aa7:d61a:0:b0:68d:205:9a90]) (user=aliceryhl job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6402:35c5:b0:695:865:47cd with SMTP id 4fb4d7f45d1cf-695086ebec3mr1540972a12.7.1781610868582; Tue, 16 Jun 2026 04:54:28 -0700 (PDT) Date: Tue, 16 Jun 2026 11:54:27 +0000 In-Reply-To: <20260604-unique-ref-v17-2-7b4c3d2930b9@kernel.org> Mime-Version: 1.0 References: <20260604-unique-ref-v17-0-7b4c3d2930b9@kernel.org> <20260604-unique-ref-v17-2-7b4c3d2930b9@kernel.org> Message-ID: Subject: Re: [PATCH v17 02/10] rust: types: Add Ownable/Owned types From: Alice Ryhl To: Andreas Hindborg Cc: Miguel Ojeda , Gary Guo , "=?utf-8?B?QmrDtnJu?= Roy Baron" , Benno Lossin , Trevor Gross , Danilo Krummrich , Greg Kroah-Hartman , Dave Ertman , Ira Weiny , Leon Romanovsky , Paul Moore , Serge Hallyn , "Rafael J. Wysocki" , David Airlie , Simona Vetter , Alexander Viro , Christian Brauner , Jan Kara , Daniel Almeida , Viresh Kumar , Nishanth Menon , Stephen Boyd , Bjorn Helgaas , "Krzysztof =?utf-8?Q?Wilczy=C5=84ski?=" , Boqun Feng , Uladzislau Rezki , Lorenzo Stoakes , Vlastimil Babka , "Liam R. Howlett" , Igor Korotin , Pavel Tikhomirov , linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-block@vger.kernel.org, linux-security-module@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-pm@vger.kernel.org, linux-pci@vger.kernel.org, driver-core@lists.linux.dev, Asahi Lina , Oliver Mangold Content-Type: text/plain; charset="utf-8" X-Rspamd-Queue-Id: 1A1E320002 X-Rspam-User: X-Stat-Signature: 5w3cksinxogdoy3t8wpx1jw8zf4a9xex X-Rspamd-Server: rspam08 X-HE-Tag: 1781642564-450548 X-HE-Meta: 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 oGZVL4E7 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 NbG8gXVq YtzQJVxc7K4JKHQ1f2I9k6ks6Vb531/PYuBHI9GLrfVCBplYFY8mHrRki4X/dPSdoernPb14F0SSiPqeG2Whrw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Jun 04, 2026 at 10:11:14PM +0200, Andreas Hindborg wrote: > From: Asahi Lina > > 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`, 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/ > Signed-off-by: Asahi Lina > Co-developed-by: Oliver Mangold > Signed-off-by: Oliver Mangold > Reviewed-by: Boqun Feng > Reviewed-by: Daniel Almeida > [ Andreas: Updated documentation, examples, and formatting. Change safety > requirements, safety comments. Use a reference for `release`. ] > Reviewed-by: Gary Guo > Co-developed-by: Andreas Hindborg > Signed-off-by: Andreas Hindborg Overall looks good to me, but two nits below. With them fixed: Reviewed-by: Alice Ryhl > +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. > 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