From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5986E25C804; Mon, 24 Aug 2026 11:19:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787570379; cv=none; b=PpUWCL3BJyRp5ufGGeIPhK6qYsYHhY/UKWybf4gDpjjOsDLKcQqBB8fvcgUGriUKVUj12DvbBiBiXVBQMThMIvVssuPE56B+8k868IC7E5dDj7CG9ZXTpmrnVwc6J4/oyLaGjOTLIvBdx5HCLUCcMq6IMg5phD4MMAemqLor8Ew= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787570379; c=relaxed/simple; bh=2rKgaZ9YnwK1gJkiYXVWR75zXX3xU5rSz64pVhI43qg=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=L9WHWOI8PNkVQby9DNhOleJ+ZK3O9j347yOATm3YYOIlDJJvHjbGP5jZ611GYvBoOEF2lL5pGJ9HMtqtmpQ2SkzCf6/rUHAXAiWX2eHhQNvxb9WgFY4+2bX5Wuoe0MVWVogb3WWoT9rBJ7lpULzhFxW8F9NR/qIrdjJnO5mrCQ8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=k4gAMO5B; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="k4gAMO5B" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CACAD1F000E9; Mon, 24 Aug 2026 11:19:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787570378; bh=FUl4cpxwoEAMk39ePpTbKQbCsCUQnhH3/2ILTsycWVk=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=k4gAMO5BvwRCt6he2XnMfQcxhipMLBwDNolB13eUen1E2wn7fAu3MBJqkfNdJr30p KtBtxAdupxFiZDW1l3khlIZo5i166WHgK9Pn+A7sa/vSe0+LeDbm8p0/efMQ/maOqb hFezxfgre2Rzvka0kHj7n6QCtLOkxvS1Bhg8inibr4T+JjjYrvDkZMTqYAfmi3k8j6 4oZ3KfuTIluGjYRLDL3kpp5vQXxd0TrKsfEdrDg/46DEbmuJqIMh5WqnKUbNs6hYOp zCXrqyY2xBjvOlklJqNgAt31S5TnrB+Usy8srISghFadNqdqLbUUZaoejrbb6VneEk HBGz5hSJfgoxA== From: Andreas Hindborg Date: Mon, 24 Aug 2026 13:17:55 +0200 Subject: [PATCH v20 3/8] rust: implement `ForeignOwnable` for `Owned` Precedence: bulk X-Mailing-List: driver-core@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260824-unique-ref-v20-3-490735672187@kernel.org> References: <20260824-unique-ref-v20-0-490735672187@kernel.org> In-Reply-To: <20260824-unique-ref-v20-0-490735672187@kernel.org> To: Danilo Krummrich , Lorenzo Stoakes , Vlastimil Babka , "Liam R. Howlett" , Uladzislau Rezki , Miguel Ojeda , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Alice Ryhl , Trevor Gross , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , =?utf-8?q?Onur_=C3=96zkan?= , Lyude Paul , Greg Kroah-Hartman , =?utf-8?q?Arve_Hj=C3=B8nnev=C3=A5g?= , Todd Kjos , Christian Brauner , Carlos Llamas , "Rafael J. Wysocki" , Dave Ertman , Leon Romanovsky , Paul Moore , Serge Hallyn , David Airlie , Simona Vetter , Alexander Viro , Jan Kara , Igor Korotin , Viresh Kumar , Nishanth Menon , Stephen Boyd , Bjorn Helgaas , =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= , Pavel Tikhomirov , Michal Wilczynski , Ira Weiny , Ira Weiny Cc: Andreas Hindborg , Philipp Stanner , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, driver-core@lists.linux.dev, linux-block@vger.kernel.org, linux-security-module@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-fsdevel@vger.kernel.org, linux-pm@vger.kernel.org, linux-pci@vger.kernel.org, linux-pwm@vger.kernel.org, linux-usb@vger.kernel.org X-Mailer: b4 0.16-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=2774; i=a.hindborg@kernel.org; h=from:subject:message-id; bh=2rKgaZ9YnwK1gJkiYXVWR75zXX3xU5rSz64pVhI43qg=; b=owEBbQKS/ZANAwAKAfpQKQiqxb3QAcsmYgBqjCiCraxhcJ+w4vvZV1SY4iZnHh7vyhYoBDHKn QKMW9sWhP+JAjMEAAEKAB0WIQRXitnI2WZ2JirAaob6UCkIqsW90AUCaowoggAKCRD6UCkIqsW9 0B6WD/96ff4wxEK2+JhzJICtEMa7fDp5dNRnYJUPIXjrv2eWMvj/7PONFiDRsfxAKSkZRZMmnB9 O8A0AaNhAuNv8rwfY1LPeVRWoOiCTsp1FtojPmOmZ8dURwpe5dEv+/YqdstPb2rvHEig/phd/z5 NCWuo+l2Xrvz1UlV0ptcV1qvzkuHDDb9C4gdkt8O/or/0CzdFXUOvC7/ur8ccqxXbWjF2IbURHF oMHferZlysAgx2DAbuQvX83sEfBBqNF5bRU5mfV6ggL3IrKaybaJfh68KWrqtqIZilPrQvRgBap OWErwdXMZDQeb577fnBxvQw4QdwJmJ5yw/Wpv1USJjvFeaUoYn8NTL4nDhOIyv2k2J1f5a23npA PFFqRK9rTt1ZeDkkXVMwlw31/NUmu10MiiyLigWpyvfNrLfhNrDQ3QPxLtst2VmNQPIwlQgJTDi 4lgouA4IUoJ1/4cU8GMhSBGKiZYBLOZpa7FRvBOSz7fsmYljgCaD7lv30wlzIsMNnyBs7iXj5qU HUf5FqukUr9Mb/8kinmk7pIsCIaUEtRk9+rP7VO7tiZAbTp5Sn7fHOELtHTTWMLaNvbvqC0tYjT RMDYuRxK7Mjj/sV7REuFDiPZVGd5wZseUkzphLtK8XVVo0kHdyhHjWzqqaR0WCiSV7grNLz1RdX m9njpTvrY5w7MyA== X-Developer-Key: i=a.hindborg@kernel.org; a=openpgp; fpr=3108C10F46872E248D1FB221376EB100563EF7A7 Implement `ForeignOwnable` for `Owned`. This allows use of `Owned` in places such as the `XArray`. Note that `T` does not need to implement `ForeignOwnable` for `Owned` to implement `ForeignOwnable`. Signed-off-by: Andreas Hindborg Reviewed-by: Gary Guo Reviewed-by: Alice Ryhl --- rust/kernel/owned.rs | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/rust/kernel/owned.rs b/rust/kernel/owned.rs index 7fe9ec3e55126..93a5dfcc1e6f5 100644 --- a/rust/kernel/owned.rs +++ b/rust/kernel/owned.rs @@ -15,6 +15,8 @@ ptr::NonNull, // }; +use kernel::types::ForeignOwnable; + /// Types that specify their own way of performing allocation and destruction. Typically, this trait /// is implemented on types from the C side. /// @@ -186,3 +188,51 @@ fn drop(&mut self) { unsafe { T::release(self.ptr) }; } } + +// SAFETY: We derive the pointer to `T` from a valid `T`, so the returned +// pointer satisfy alignment requirements of `T`. +unsafe impl ForeignOwnable for Owned { + const FOREIGN_ALIGN: usize = core::mem::align_of::(); + + type Borrowed<'a> + = &'a T + where + Self: 'a; + type BorrowedMut<'a> + = Pin<&'a mut T> + where + Self: 'a; + + #[inline] + fn into_foreign(self) -> *mut kernel::ffi::c_void { + Owned::into_raw(self).as_ptr().cast() + } + + #[inline] + unsafe fn from_foreign(ptr: *mut kernel::ffi::c_void) -> Self { + // SAFETY: By function safety contract, `ptr` came from `into_foreign` and cannot be null. + let ptr = unsafe { NonNull::new_unchecked(ptr.cast()) }; + + // SAFETY: By the function safety contract, `ptr` was returned by `into_foreign`, which gave + // up exclusive ownership of a valid, pinned `T`; we retake that ownership here. + unsafe { Owned::from_raw(ptr) } + } + + #[inline] + unsafe fn borrow<'a>(ptr: *mut kernel::ffi::c_void) -> Self::Borrowed<'a> { + // SAFETY: By function safety requirements, `ptr` is valid for use as a + // reference for `'a`. + unsafe { &*ptr.cast() } + } + + #[inline] + unsafe fn borrow_mut<'a>(ptr: *mut kernel::ffi::c_void) -> Self::BorrowedMut<'a> { + // SAFETY: By function safety requirements, `ptr` is valid for use as a + // unique reference for `'a`. + let inner = unsafe { &mut *ptr.cast() }; + + // SAFETY: We never move out of inner, and we do not hand out mutable + // references when `T: !Unpin`. + unsafe { Pin::new_unchecked(inner) } + } +} -- 2.51.2