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 F322FC77B6C for ; Wed, 5 Apr 2023 21:35:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232849AbjDEVfQ (ORCPT ); Wed, 5 Apr 2023 17:35:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50558 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232560AbjDEVfN (ORCPT ); Wed, 5 Apr 2023 17:35:13 -0400 Received: from mail-ed1-x531.google.com (mail-ed1-x531.google.com [IPv6:2a00:1450:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 16A6A7A9F for ; Wed, 5 Apr 2023 14:35:11 -0700 (PDT) Received: by mail-ed1-x531.google.com with SMTP id w9so144556946edc.3 for ; Wed, 05 Apr 2023 14:35:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=metaspace-dk.20210112.gappssmtp.com; s=20210112; t=1680730509; h=mime-version:message-id:in-reply-to:date:subject:cc:to:from :user-agent:references:from:to:cc:subject:date:message-id:reply-to; bh=XsbPLOoZy3IpCVle9f3gfXkiDPXo3wFa1tXKUWRKGVg=; b=p0m+HR1QQ3N+oi6geD/qwqW7kEa4uqZsXJHk3StcmFJTsjTxSXLBuJzEZeKbVTf69X kFBbgPdfJSIEl/j6MZSWFMzNZGHFg5HKSvg6l11ehsHq/GnWjreNi6Q1bZkhL9sYl95b 4Z25B1HJt1GmR9s+9S8Co0m+ZRaLZ4ybI+ycA+nqBqoG8oIP5cnStCEvCoy5dIDcNmhJ ngslMDl5mQT3FdIBE8Kvt9U7M09W8YG6drbBl7KKd5rxT3Sh/N4po3g64M7coBnRUg9S vtXRjhhaRDha82MZ8NK1Q5cptG4C0r7yeCUIwSSgB4sXhHpjyFnsjnwbVxrbLBud7xU4 oSnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680730509; h=mime-version:message-id:in-reply-to:date:subject:cc:to:from :user-agent:references:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=XsbPLOoZy3IpCVle9f3gfXkiDPXo3wFa1tXKUWRKGVg=; b=Fm7vh84slozWA0TNG1+LeS34twAYNpFkVSe7VRhIOdk4MR0RlncaZsCvXPHbO+a3W/ U8gbuz5KDl9wMivaOkRYgTmdrqe4S/EDMzJHx2HYcUkppRB65dqigggoDJvwej1VL86I JujMASa8HAQdauQq2LkPG5PgSHk7uMT7lmGFBlnWIyiLOsfQsy1/Ebztwqph3iyqOvaE F2t8XH1sv++jB8T5g0DNEpuZ8w+DFKjwOo4hR9P0+PgfLV+YN5RzQ1p9qQANaAvdHNb9 //pd+lv/EUbfU0Ry8H8LD0/hU2LxMSa9Yo8rggYhaP9WfB+otlVui0hoWrstg//bhGtG u4lA== X-Gm-Message-State: AAQBX9eDHsWD7h5gVU6M14cRRFhA0sE20LQ8Slfj5NNVa0Idjqvl1tk8 DhvTwGYpeYInonHbk50riuokwg== X-Google-Smtp-Source: AKy350Y1d7gbDVVNTMqhI+CI6pBTgOs7TRKtMFmndCYIelLHIglwKV/vWSWJO9AopwvBlNldCSA+6A== X-Received: by 2002:a17:906:d79b:b0:93f:9b68:a0f4 with SMTP id pj27-20020a170906d79b00b0093f9b68a0f4mr3707529ejb.26.1680730509442; Wed, 05 Apr 2023 14:35:09 -0700 (PDT) Received: from localhost ([79.142.230.34]) by smtp.gmail.com with ESMTPSA id qp24-20020a170907207800b0093f822321fesm7799826ejb.137.2023.04.05.14.35.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Apr 2023 14:35:09 -0700 (PDT) References: <20230405193445.745024-1-y86-dev@protonmail.com> <20230405193445.745024-9-y86-dev@protonmail.com> User-agent: mu4e 1.10.1; emacs 28.2.50 From: Andreas Hindborg To: Benno Lossin Cc: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn?= Roy Baron , Alice Ryhl , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Alice Ryhl , Andreas Hindborg Subject: Re: [PATCH v6 08/15] rust: init/sync: add `InPlaceInit` trait to pin-initialize smart pointers Date: Wed, 05 Apr 2023 23:34:35 +0200 In-reply-to: <20230405193445.745024-9-y86-dev@protonmail.com> Message-ID: <87355et3lf.fsf@metaspace.dk> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Benno Lossin writes: > 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 > Reviewed-by: Alice Ryhl > Reviewed-by: Gary Guo > Cc: Andreas Hindborg > --- Reviewed-by: Andreas Hindborg > 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::MaybeUninit, ptr}; > +use core::{ > + alloc::AllocError, cell::Cell, convert::Infallible, marker::PhantomData, 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 documentation 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 documentation 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 documentation 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 documentation 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::pin_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 = "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::init`] 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 = "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 = 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 = 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 = Box::try_new_uninit()?; > + let slot = 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 = Box::try_new_uninit()?; > + let slot = 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 = UniqueArc::try_new_uninit()?; > + let slot = 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 = UniqueArc::try_new_uninit()?; > + let slot = 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 pinned. > + #[inline] > + pub fn init(init: impl Init) -> error::Result > + where > + Error: From, > + { > + UniqueArc::init(init).map(|u| u.into()) > + } > } > > impl Arc {