From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 77091C55183 for ; Fri, 20 Feb 2026 09:52:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D56B36B008A; Fri, 20 Feb 2026 04:52:01 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id CD9DA6B008C; Fri, 20 Feb 2026 04:52:01 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id BDC9C6B0092; Fri, 20 Feb 2026 04:52:01 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id AAB1A6B008A for ; Fri, 20 Feb 2026 04:52:01 -0500 (EST) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 6B2FD160C49 for ; Fri, 20 Feb 2026 09:52:01 +0000 (UTC) X-FDA: 84464368842.06.AC9F05F Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf30.hostedemail.com (Postfix) with ESMTP id 84CAE80016 for ; Fri, 20 Feb 2026 09:51:59 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=TBlUoq08; spf=pass (imf30.hostedemail.com: domain of a.hindborg@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=a.hindborg@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1771581119; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=fEYMJwatXgPu+YWsD6k99uwLF7wZEliuaUYi50HKU1Y=; b=A2Rtcwbb3JIjVeKekqOM0wglOF0PneSYqjLyjnb+kEqier+dxSZYYPPNs8ALD0kjMayrtk 8Ro9AzMh2XfaM0IASTnojoGrHQYDA/zN3SWMS5SJHd635N5tkMky2MUlNwmVLjKYjUoURd oNlR635HQpKIV2pzwMFGBMININIkRDE= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1771581119; a=rsa-sha256; cv=none; b=ZlGlZwdOddu/WPBS8Y6rw2XhUIx/OVCP4XmOkYUjanGze0caU4pw0NmowcqkLEpVYbEGvz iP9urox5vO/kJjC1OlvT4eh8DVlwOTsfCwoc6cn67vlYQdtV6hkz/TUrmzRKCGSUJyuAFP YQOvPZscaMPzW96l2VRtjxxRg9lsJZo= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=TBlUoq08; spf=pass (imf30.hostedemail.com: domain of a.hindborg@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=a.hindborg@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 5895943BE1; Fri, 20 Feb 2026 09:51:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2FC2AC116C6; Fri, 20 Feb 2026 09:51:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771581118; bh=B5FbaZHoWu3lXzLWsvxiL2xffXnxnFX4nBQhSLyFXlg=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=TBlUoq08h8THjyqgOPa5qFuSUJ9EA2rl/GDN9uRVQwt25XUkK2RxR0vWqjtTL+7yR cxoufxtl3dRE9KagTQfI7RkbgRykxBYpq8jJ357TWuSs3n6WeNy78TnJ/OsGZlbPKT Thm6Otw7Q8bFXfFocqjTXBUKiV7Vq5W/wpQDQS4W6T/s8x/iBPpgcY0S/jf3hOLE33 0EliLnOFmz9t6PWADdrJir83Vzp8lwr1ATpcd8KGS9kH3OtcrnuhXChO/0fBhJkudy zok60YIdfXuLJ3TKGwePrpf4o1T+iRXL6mZVb9VWayQRcEU3mgx8PQfbIuGjqMAxUD GWwJKsOvDrPrg== From: Andreas Hindborg Date: Fri, 20 Feb 2026 10:51:17 +0100 Subject: [PATCH v15 8/9] rust: implement `ForeignOwnable` for `Owned` MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260220-unique-ref-v15-8-893ed86b06cc@kernel.org> References: <20260220-unique-ref-v15-0-893ed86b06cc@kernel.org> In-Reply-To: <20260220-unique-ref-v15-0-893ed86b06cc@kernel.org> To: Miguel Ojeda , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Alice Ryhl , Trevor Gross , Danilo Krummrich , Greg Kroah-Hartman , Dave Ertman , Ira Weiny , Leon Romanovsky , Paul Moore , Serge Hallyn , "Rafael J. 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Howlett" , Viresh Kumar , Nishanth Menon , Stephen Boyd , Bjorn Helgaas , =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= , Boqun Feng , Boqun Feng Cc: 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, Andreas Hindborg X-Mailer: b4 0.15-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=2835; i=a.hindborg@kernel.org; h=from:subject:message-id; bh=B5FbaZHoWu3lXzLWsvxiL2xffXnxnFX4nBQhSLyFXlg=; b=owEBbQKS/ZANAwAKAeG4Gj55KGN3AcsmYgBpmC6lQ8ViWhXfTBxkBwYXwCvpZEQQpsFdLjSWt Z/0DPcp01iJAjMEAAEKAB0WIQQSwflHVr98KhXWwBLhuBo+eShjdwUCaZgupQAKCRDhuBo+eShj dynCD/wPCHcbzgHFtI1xHdF07F3Sl7RvyuqebxX7QafkNthmS2wK+6fYvfrTUdnL1z/OBT1a29v Ekv+847w5ksZlRBgGMKWxazpNxfKF5eWQvBoKPWlYxkyWDMvo5kyar5hxw0w3x3COrfeu9QKl56 KhsRSpsbaevfgdJSut7YliqvTpAiGKoUhon8VZJN9MfpgxHFA8h4daaTbVL7VknN+9j2z7j7sy1 Sgk87Kl23zumku0CP8xCTL/v2iQdTZkeAo0DqBaYMIqW99TDPpzpfzfY0vMKWUdz3CKfi0NVOL1 ha+JjyDc1y9rbdiDLBax6CvmSMa3YTUcETVRBpfR1iK9Nv5jfwJ/ahTThdwfuq27a98NOsjeZM7 xSMg0DOPOZm2bogbOUFEwQxYUeZawSZw5998KQzSnn9YHKJwKEyRhqKqLDSfv8O35BgPsTCYfZx ulAarVM09f3S8iZXGFdpWCwIIZXvoyMEV5vsnhvNxrcgESzwem5PCkmknWlGyJB4BTjaB7CVwu4 EhB+2yo3w2A6G3YxFFEK2Y+4pBEXalKlRTVLSKaOAPoKkXmw4MtJptUOgpKFlnAlWsJJPvDVAPX Zj4fG0pZkGwmYQf3x8c6EhW/QFvUIWp3kCah+QYzszA1iz7lJcu0LsCpfHpmCOqa9mFhCq4JFVx H3Cwg/+isbapMRQ== X-Developer-Key: i=a.hindborg@kernel.org; a=openpgp; fpr=3108C10F46872E248D1FB221376EB100563EF7A7 X-Rspam-User: X-Stat-Signature: b59b7364f4cp7y3tjw3kjokm8qnj9by3 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 84CAE80016 X-HE-Tag: 1771581119-559713 X-HE-Meta: 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 Iw4gywFS WzAjm8H6rFxrRjIbqnhKlpN8tl9YHxghDeLa3TqES1NQXvkLV+w5ucpA/7VntREpOxPBhLilqp/nSVnH3aFIV2cJaPn4zodQy8/Ad82C7klEtkSc6lqVgKXAc6wte2Q9G49p851w3M2aKI6J4Ll+FwPm7qJOMv9cJCALzGj+8TINe4SmIUiurDAMw8XS32CTLYb1v13A4K+kcUO6FHQ4lZjIM84HeA7DXugTuShaR5DSQbO9jvmtqZ9h5653b59qH9gJ1Tu+K/z1tK7xW9PjB67QxgfteCPuTVu9uNbDHR4c7D/OzQccixExwPSeYirMZPE4W X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 --- rust/kernel/owned.rs | 45 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 44 insertions(+), 1 deletion(-) diff --git a/rust/kernel/owned.rs b/rust/kernel/owned.rs index a9bc871e07ce1..b115b4f3db6d0 100644 --- a/rust/kernel/owned.rs +++ b/rust/kernel/owned.rs @@ -16,7 +16,10 @@ }; use kernel::{ sync::aref::ARef, - types::RefCounted, // + types::{ + ForeignOwnable, // + RefCounted, + }, // }; /// Types that specify their own way of performing allocation and destruction. Typically, this trait @@ -120,6 +123,7 @@ pub unsafe trait Ownable { /// /// - The [`Owned`] has exclusive access to the instance of `T`. /// - The instance of `T` will stay alive at least as long as the [`Owned`] is alive. +#[repr(transparent)] pub struct Owned { ptr: NonNull, } @@ -201,6 +205,45 @@ fn drop(&mut self) { } } +// 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; + type BorrowedMut<'a> = Pin<&'a mut T>; + + fn into_foreign(self) -> *mut kernel::ffi::c_void { + let ptr = self.ptr.as_ptr().cast(); + core::mem::forget(self); + ptr + } + + unsafe fn from_foreign(ptr: *mut kernel::ffi::c_void) -> Self { + Self { + // SAFETY: By function safety contract, `ptr` came from + // `into_foreign` and cannot be null. + ptr: unsafe { NonNull::new_unchecked(ptr.cast()) }, + } + } + + 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() } + } + + 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) } + } +} + /// A trait for objects that can be wrapped in either one of the reference types [`Owned`] and /// [`ARef`]. /// -- 2.51.2