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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DD6FC76188 for ; Mon, 3 Apr 2023 16:05:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233172AbjDCQFw (ORCPT ); Mon, 3 Apr 2023 12:05:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232892AbjDCQFp (ORCPT ); Mon, 3 Apr 2023 12:05:45 -0400 Received: from mail-40134.protonmail.ch (mail-40134.protonmail.ch [185.70.40.134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CF5412121 for ; Mon, 3 Apr 2023 09:05:43 -0700 (PDT) Date: Mon, 03 Apr 2023 16:05:22 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680537941; x=1680797141; bh=P8epafKhZXNsBb4h/KIdTrILNE/pnVEGDygcW+mztsA=; h=Date:To:From:Cc:Subject:Message-ID:In-Reply-To:References: Feedback-ID:From:To:Cc:Date:Subject:Reply-To:Feedback-ID: Message-ID:BIMI-Selector; b=r16AsU4NDng+C6NhWCe/YhavkKGPFLBu/XrA8YWh0M4qQ+0cpsWHWjBHL0LAff40u lhrsjDCuoZJj+RpXduVodd6ueJ/AZJ+OQAEx7iNynynr4dP82Tpc65UEVpM1Yk5QBQ E5fIkp5T5rMKIUn5wqP/tNElUeta7YHlTaLWCi+IagfyHFA8jYs5Oe/P7sFj05aoFe dVYb5ZpjQ9l7o6vFRYsElQA463EAjuFdg0tMnL4AKlFKpV++m4O/1hQek529RI3UgU wY9gBdV1c8K0Vjs3xdPLd3Lthq/MnuJfXwe4xUZ7+eb5xGzxbt1ymPxACLMcLy1iEz y2HDMF3N9MEkg== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Andreas Hindborg , Alice Ryhl Subject: [PATCH v5 08/15] rust: init/sync: add `InPlaceInit` trait to pin-initialize smart pointers Message-ID: <20230403160511.174894-1-y86-dev@protonmail.com> In-Reply-To: <20230403154422.168633-1-y86-dev@protonmail.com> References: <20230403154422.168633-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: rust-for-linux@vger.kernel.org The `InPlaceInit` trait that provides two functions, for initializing using `PinInit` and `Init`. It is implemented by `Arc`, `UniqueArc` and `Box`. Signed-off-by: Benno Lossin Cc: Andreas Hindborg Cc: Alice Ryhl Cc: Gary Guo --- rust/kernel/init.rs | 128 ++++++++++++++++++++++++++++++++++++---- rust/kernel/sync/arc.rs | 24 ++++++++ 2 files changed, 139 insertions(+), 13 deletions(-) diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index ecef0376d726..6499cf5c9c20 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -114,10 +114,16 @@ //! [`impl Init`]: Init //! [`Opaque`]: kernel::types::Opaque //! [`pin_data`]: ::macros::pin_data -//! [`UniqueArc`]: kernel::sync::UniqueArc +use crate::{ + error::{self, Error}, + sync::UniqueArc, +}; use alloc::boxed::Box; -use core::{cell::Cell, convert::Infallible, marker::PhantomData, mem::Mayb= eUninit, ptr}; +use core::{ + alloc::AllocError, cell::Cell, convert::Infallible, marker::PhantomDat= a, mem::MaybeUninit, + pin::Pin, ptr, +}; #[doc(hidden)] pub mod __internal; @@ -309,7 +315,6 @@ pub mod macros; /// /// [`try_pin_init!`]: kernel::try_pin_init /// [`NonNull`]: core::ptr::NonNull -/// [`Error`]: kernel::error::Error // For a detailed example of how this macro works, see the module document= ation of the hidden // module `__internal` inside of `init/__internal.rs`. #[macro_export] @@ -363,8 +368,6 @@ macro_rules! pin_init { /// } /// } /// ``` -/// -/// [`Error`]: kernel::error::Error // For a detailed example of how this macro works, see the module document= ation of the hidden // module `__internal` inside of `init/__internal.rs`. #[macro_export] @@ -586,8 +589,6 @@ macro_rules! try_pin_init { /// /// This initializer is for initializing data in-place that might later be= moved. If you want to /// pin-initialize, use [`pin_init!`]. -/// -/// [`Error`]: kernel::error::Error // For a detailed example of how this macro works, see the module document= ation of the hidden // module `__internal` inside of `init/__internal.rs`. #[macro_export] @@ -635,8 +636,6 @@ macro_rules! init { /// } /// } /// ``` -/// -/// [`Error`]: kernel::error::Error // For a detailed example of how this macro works, see the module document= ation of the hidden // module `__internal` inside of `init/__internal.rs`. #[macro_export] @@ -842,7 +841,8 @@ macro_rules! try_init { /// A pin-initializer for the type `T`. /// /// To use this initializer, you will need a suitable memory location that= can hold a `T`. This can -/// be [`Box`], [`Arc`], [`UniqueArc`]. +/// be [`Box`], [`Arc`], [`UniqueArc`]. Use the [`InPlaceInit::pi= n_init`] function of a +/// smart pointer like [`Arc`] on this. /// /// Also see the [module description](self). /// @@ -861,7 +861,6 @@ macro_rules! try_init { /// /// [`Arc`]: crate::sync::Arc /// [`Arc::pin_init`]: crate::sync::Arc::pin_init -/// [`UniqueArc`]: kernel::sync::UniqueArc #[must_use =3D "An initializer must be used in order to create its value."= ] pub unsafe trait PinInit: Sized { /// Initializes `slot`. @@ -878,7 +877,8 @@ pub unsafe trait PinInit: = Sized { /// An initializer for `T`. /// /// To use this initializer, you will need a suitable memory location that= can hold a `T`. This can -/// be [`Box`], [`Arc`], [`UniqueArc`]. Because [`PinInit`]= is a super trait, you can +/// be [`Box`], [`Arc`], [`UniqueArc`]. Use the [`InPlaceInit::in= it`] function of a smart +/// pointer like [`Arc`] on this. Because [`PinInit`] is a super = trait, you can /// use every function that takes it as well. /// /// Also see the [module description](self). @@ -903,7 +903,6 @@ pub unsafe trait PinInit: = Sized { /// move the pointee after initialization. /// /// [`Arc`]: crate::sync::Arc -/// [`UniqueArc`]: kernel::sync::UniqueArc #[must_use =3D "An initializer must be used in order to create its value."= ] pub unsafe trait Init: Sized { /// Initializes `slot`. @@ -982,3 +981,106 @@ unsafe impl Init for T { Ok(()) } } + +/// Smart pointer that can initialize memory in-place. +pub trait InPlaceInit: Sized { + /// Use the given pin-initializer to pin-initialize a `T` inside of a = new smart pointer of this + /// type. + /// + /// If `T: !Unpin` it will not be able to move afterwards. + fn try_pin_init(init: impl PinInit) -> Result, E> + where + E: From; + + /// Use the given pin-initializer to pin-initialize a `T` inside of a = new smart pointer of this + /// type. + /// + /// If `T: !Unpin` it will not be able to move afterwards. + fn pin_init(init: impl PinInit) -> error::Result> + where + Error: From, + { + // SAFETY: We delegate to `init` and only change the error type. + let init =3D unsafe { + pin_init_from_closure(|slot| init.__pinned_init(slot).map_err(= |e| Error::from(e))) + }; + Self::try_pin_init(init) + } + + /// Use the given initializer to in-place initialize a `T`. + fn try_init(init: impl Init) -> Result + where + E: From; + + /// Use the given initializer to in-place initialize a `T`. + fn init(init: impl Init) -> error::Result + where + Error: From, + { + // SAFETY: We delegate to `init` and only change the error type. + let init =3D unsafe { + init_from_closure(|slot| init.__pinned_init(slot).map_err(|e| = Error::from(e))) + }; + Self::try_init(init) + } +} + +impl InPlaceInit for Box { + #[inline] + fn try_pin_init(init: impl PinInit) -> Result, E> + where + E: From, + { + let mut this =3D Box::try_new_uninit()?; + let slot =3D this.as_mut_ptr(); + // SAFETY: When init errors/panics, slot will get deallocated but = not dropped, + // slot is valid and will not be moved, because we pin it later. + unsafe { init.__pinned_init(slot)? }; + // SAFETY: All fields have been initialized. + Ok(unsafe { this.assume_init() }.into()) + } + + #[inline] + fn try_init(init: impl Init) -> Result + where + E: From, + { + let mut this =3D Box::try_new_uninit()?; + let slot =3D this.as_mut_ptr(); + // SAFETY: When init errors/panics, slot will get deallocated but = not dropped, + // slot is valid. + unsafe { init.__init(slot)? }; + // SAFETY: All fields have been initialized. + Ok(unsafe { this.assume_init() }) + } +} + +impl InPlaceInit for UniqueArc { + #[inline] + fn try_pin_init(init: impl PinInit) -> Result, E> + where + E: From, + { + let mut this =3D UniqueArc::try_new_uninit()?; + let slot =3D this.as_mut_ptr(); + // SAFETY: When init errors/panics, slot will get deallocated but = not dropped, + // slot is valid and will not be moved, because we pin it later. + unsafe { init.__pinned_init(slot)? }; + // SAFETY: All fields have been initialized. + Ok(unsafe { this.assume_init() }.into()) + } + + #[inline] + fn try_init(init: impl Init) -> Result + where + E: From, + { + let mut this =3D UniqueArc::try_new_uninit()?; + let slot =3D this.as_mut_ptr(); + // SAFETY: When init errors/panics, slot will get deallocated but = not dropped, + // slot is valid. + unsafe { init.__init(slot)? }; + // SAFETY: All fields have been initialized. + Ok(unsafe { this.assume_init() }) + } +} diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index eee7008e5e3e..43a53fbe175d 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -17,6 +17,8 @@ use crate::{ bindings, + error::{self, Error}, + init::{InPlaceInit, Init, PinInit}, types::{ForeignOwnable, Opaque}, }; use alloc::boxed::Box; @@ -163,6 +165,28 @@ impl Arc { // `Arc` object. Ok(unsafe { Self::from_inner(Box::leak(inner).into()) }) } + + /// Use the given initializer to in-place initialize a `T`. + /// + /// If `T: !Unpin` it will not be able to move afterwards. + #[inline] + pub fn pin_init(init: impl PinInit) -> error::Result + where + Error: From, + { + UniqueArc::pin_init(init).map(|u| u.into()) + } + + /// Use the given initializer to in-place initialize a `T`. + /// + /// This is equivalent to [`pin_init`], since an [`Arc`] is always pin= ned. + #[inline] + pub fn init(init: impl Init) -> error::Result + where + Error: From, + { + UniqueArc::init(init).map(|u| u.into()) + } } impl Arc { -- 2.39.2