From nobody Sun Feb 8 01:31:22 2026 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 A072CC7619A for ; Sat, 8 Apr 2023 12:25:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230171AbjDHMZh (ORCPT ); Sat, 8 Apr 2023 08:25:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60064 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229888AbjDHMZc (ORCPT ); Sat, 8 Apr 2023 08:25:32 -0400 Received: from mail-4322.protonmail.ch (mail-4322.protonmail.ch [185.70.43.22]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9399CFF0F; Sat, 8 Apr 2023 05:25:31 -0700 (PDT) Date: Sat, 08 Apr 2023 12:25:18 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956729; x=1681215929; bh=Li9vFOtyOn1yzZsM8xsVc5+dXMyMO7EVK2qob/N7lA8=; 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=TRYjC4gVMn/a6jq0zUpOGC9+Us99TXZ3EPJ9M/Q0Zr+iqSmQHT7eicBvYtlZ/cyES /e7gKccqGecOFm+XJgttupJD2mTcYygdSkR8nR+pInbH0zXY5Q9VL2i21cxRS9kJNP H+g69O7PNbPIlvR0lkH5+ivWTn4IcM44Nj4SSAOYQCV2+tJuXWgMGGwG6sAcy72CMv HCoV785h+6h/zg+2KrCYSUrHGIG+p8oby5HbBotBDaB6Mq4ox5ox2ZEMTEOQXwTUw8 bNM2MnwCzj47+E3yviTYfZwKCtdEr+AlpOkt/7iGSEe8LYCYeSJ4xRvPQS3cc5OSxa 4yCmUz7YhAWfg== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Alice Ryhl , Andreas Hindborg Subject: [PATCH v7 01/15] rust: enable the `pin_macro` feature Message-ID: <20230408122429.1103522-2-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" This feature enables the use of the `pin!` macro for the `stack_pin_init!` macro. This feature is already stabilized in Rust version 1.68. Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Reviewed-by: Andreas Hindborg Acked-by: Boqun Feng --- rust/kernel/lib.rs | 1 + scripts/Makefile.build | 2 +- 2 files changed, 2 insertions(+), 1 deletion(-) diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 223564f9f0cc..4317b6d5f50b 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -17,6 +17,7 @@ #![feature(core_ffi_c)] #![feature(dispatch_from_dyn)] #![feature(generic_associated_types)] +#![feature(pin_macro)] #![feature(receiver_trait)] #![feature(unsize)] diff --git a/scripts/Makefile.build b/scripts/Makefile.build index 76323201232a..ba4102b9d94d 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -277,7 +277,7 @@ $(obj)/%.lst: $(src)/%.c FORCE # Compile Rust sources (.rs) # ------------------------------------------------------------------------= --- -rust_allowed_features :=3D core_ffi_c +rust_allowed_features :=3D core_ffi_c,pin_macro rust_common_cmd =3D \ RUST_MODFILE=3D$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \ -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 A79ABC77B70 for ; Sat, 8 Apr 2023 12:25:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230093AbjDHMZj (ORCPT ); Sat, 8 Apr 2023 08:25:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229914AbjDHMZg (ORCPT ); Sat, 8 Apr 2023 08:25:36 -0400 Received: from mail-40133.protonmail.ch (mail-40133.protonmail.ch [185.70.40.133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62B49FF0E for ; Sat, 8 Apr 2023 05:25:35 -0700 (PDT) Date: Sat, 08 Apr 2023 12:25:23 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956733; x=1681215933; bh=K9JbIFZF8PegFhJuUFtlmmuNCJL0YgKAbcJnn1iYflI=; 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=xyxNIwI5rbLIDZRXv6V8QWw/emXcOZO2V0U++S4GLVil8TNtAseaDnoeznUnGmurX RQHjT5gNMUSagRlWnmJWeoyIfxzaSHrhbSph+8Sh5rCoF2GWB69LDHqOdzq4PKpd// MX4dRnj23UDTjI7PsNOf2PPnvq08qepMmmiuQU3fX0E/6oGVIalymfvUrE44V47P6G bDgG3c7e7djLmNm+qypzrWcxlvi7+B7NI8jH4bDMuuqxLi3El19b4wYGqLO/OsGMyF pV9ms3oQnFKdXNVlrychje6q0MaT6hMBnfuRA912x3lFBCX2zdC+z0CYodga3UA/qG WAE8i05K/bp5g== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg 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 v7 02/15] rust: macros: add `quote!` macro Message-ID: <20230408122429.1103522-3-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Gary Guo Add the `quote!` macro for creating `TokenStream`s directly via the given Rust tokens. It also supports repetitions using iterators. It will be used by the pin-init API proc-macros to generate code. Signed-off-by: Gary Guo Signed-off-by: Benno Lossin Reviewed-by: Andreas Hindborg Reviewed-by: Alice Ryhl --- rust/macros/lib.rs | 2 + rust/macros/quote.rs | 145 +++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 147 insertions(+) create mode 100644 rust/macros/quote.rs diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index c1d385e345b9..82b520f024dd 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -2,6 +2,8 @@ //! Crate for all kernel procedural macros. +#[macro_use] +mod quote; mod concat_idents; mod helpers; mod module; diff --git a/rust/macros/quote.rs b/rust/macros/quote.rs new file mode 100644 index 000000000000..94a6277182ee --- /dev/null +++ b/rust/macros/quote.rs @@ -0,0 +1,145 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +use proc_macro::{TokenStream, TokenTree}; + +pub(crate) trait ToTokens { + fn to_tokens(&self, tokens: &mut TokenStream); +} + +impl ToTokens for Option { + fn to_tokens(&self, tokens: &mut TokenStream) { + if let Some(v) =3D self { + v.to_tokens(tokens); + } + } +} + +impl ToTokens for proc_macro::Group { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.extend([TokenTree::from(self.clone())]); + } +} + +impl ToTokens for TokenTree { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.extend([self.clone()]); + } +} + +impl ToTokens for TokenStream { + fn to_tokens(&self, tokens: &mut TokenStream) { + tokens.extend(self.clone()); + } +} + +/// Converts tokens into [`proc_macro::TokenStream`] and performs variable= interpolations with +/// the given span. +/// +/// This is a similar to the +/// [`quote_spanned!`](https://docs.rs/quote/latest/quote/macro.quote_span= ned.html) macro from the +/// `quote` crate but provides only just enough functionality needed by th= e current `macros` crate. +#[allow(unused_macros)] +macro_rules! quote_spanned { + ($span:expr =3D> $($tt:tt)*) =3D> { + #[allow(clippy::vec_init_then_push)] + { + let mut tokens =3D ::std::vec::Vec::new(); + let span =3D $span; + quote_spanned!(@proc tokens span $($tt)*); + ::proc_macro::TokenStream::from_iter(tokens) + }}; + (@proc $v:ident $span:ident) =3D> {}; + (@proc $v:ident $span:ident #$id:ident $($tt:tt)*) =3D> { + let mut ts =3D ::proc_macro::TokenStream::new(); + $crate::quote::ToTokens::to_tokens(&$id, &mut ts); + $v.extend(ts); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident #(#$id:ident)* $($tt:tt)*) =3D> { + for token in $id { + let mut ts =3D ::proc_macro::TokenStream::new(); + $crate::quote::ToTokens::to_tokens(&token, &mut ts); + $v.extend(ts); + } + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident ( $($inner:tt)* ) $($tt:tt)*) =3D> { + let mut tokens =3D ::std::vec::Vec::new(); + quote_spanned!(@proc tokens $span $($inner)*); + $v.push(::proc_macro::TokenTree::Group(::proc_macro::Group::new( + ::proc_macro::Delimiter::Parenthesis, + ::proc_macro::TokenStream::from_iter(tokens) + ))); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident [ $($inner:tt)* ] $($tt:tt)*) =3D> { + let mut tokens =3D ::std::vec::Vec::new(); + quote_spanned!(@proc tokens $span $($inner)*); + $v.push(::proc_macro::TokenTree::Group(::proc_macro::Group::new( + ::proc_macro::Delimiter::Bracket, + ::proc_macro::TokenStream::from_iter(tokens) + ))); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident { $($inner:tt)* } $($tt:tt)*) =3D> { + let mut tokens =3D ::std::vec::Vec::new(); + quote_spanned!(@proc tokens $span $($inner)*); + $v.push(::proc_macro::TokenTree::Group(::proc_macro::Group::new( + ::proc_macro::Delimiter::Brace, + ::proc_macro::TokenStream::from_iter(tokens) + ))); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident :: $($tt:tt)*) =3D> { + $v.push(::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new(':', ::proc_macro::Spacing::Joint) + )); + $v.push(::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new(':', ::proc_macro::Spacing::Alone) + )); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident : $($tt:tt)*) =3D> { + $v.push(::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new(':', ::proc_macro::Spacing::Alone) + )); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident , $($tt:tt)*) =3D> { + $v.push(::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new(',', ::proc_macro::Spacing::Alone) + )); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident @ $($tt:tt)*) =3D> { + $v.push(::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new('@', ::proc_macro::Spacing::Alone) + )); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident ! $($tt:tt)*) =3D> { + $v.push(::proc_macro::TokenTree::Punct( + ::proc_macro::Punct::new('!', ::proc_macro::Spacing::Alone) + )); + quote_spanned!(@proc $v $span $($tt)*); + }; + (@proc $v:ident $span:ident $id:ident $($tt:tt)*) =3D> { + $v.push(::proc_macro::TokenTree::Ident(::proc_macro::Ident::new(st= ringify!($id), $span))); + quote_spanned!(@proc $v $span $($tt)*); + }; +} + +/// Converts tokens into [`proc_macro::TokenStream`] and performs variable= interpolations with +/// mixed site span ([`Span::mixed_site()`]). +/// +/// This is a similar to the [`quote!`](https://docs.rs/quote/latest/quote= /macro.quote.html) macro +/// from the `quote` crate but provides only just enough functionality nee= ded by the current +/// `macros` crate. +/// +/// [`Span::mixed_site()`]: https://doc.rust-lang.org/proc_macro/struct.Sp= an.html#method.mixed_site +#[allow(unused_macros)] +macro_rules! quote { + ($($tt:tt)*) =3D> { + quote_spanned!(::proc_macro::Span::mixed_site() =3D> $($tt)*) + } +} -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 F1AF1C77B71 for ; Sat, 8 Apr 2023 12:25:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230194AbjDHMZm (ORCPT ); Sat, 8 Apr 2023 08:25:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60164 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230170AbjDHMZh (ORCPT ); Sat, 8 Apr 2023 08:25:37 -0400 Received: from mail-4316.protonmail.ch (mail-4316.protonmail.ch [185.70.43.16]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 184BCFF2B for ; Sat, 8 Apr 2023 05:25:35 -0700 (PDT) Date: Sat, 08 Apr 2023 12:25:29 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956734; x=1681215934; bh=/3m6gBMij6Ax7PcQaOILDRRx86A/6McrrYe3eb+j60U=; 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=gmiZT8rEZ4T5b4rbZc4Llt40scAmwCy+zVC8Goi1+xfTTA9TQHB1/7NRbEODLxbNA ElegjFBERD91wYJVeZDAb4KnE58lNeyBvLG/lQ4Xs+7hMcKoUxbkz+CPDc/3LtBPhV DPRIA1MjRFy2kbfL+ISWZ0IKcBdFkoYMAA4lMiAl6pk0PagRKCCOX4P+0xCZG8rPqI /A9OKveMcD3pSPSNPv0rilXwCGcpG9Pr0wjs5rgu7Hvh0jY/trkFRh/FI8mM90jErr Uipnf+KhJnLI9hiVsHxtaq2Ky+ECE8HjwlaBxhWTF/VGA4tg5kEzsuoJ0vKnN/OyUx lTyx1YV3J2Idw== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg 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 v7 03/15] rust: sync: change error type of constructor functions Message-ID: <20230408122429.1103522-4-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Change the error type of the constructors of `Arc` and `UniqueArc` to be `AllocError` instead of `Error`. This makes the API more clear as to what can go wrong when calling `try_new` or its variants. Signed-off-by: Benno Lossin Reviewed-by: Andreas Hindborg Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo --- rust/kernel/sync/arc.rs | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index f2f1c83d72ba..aa7135f0f238 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -17,11 +17,11 @@ use crate::{ bindings, - error::Result, types::{ForeignOwnable, Opaque}, }; use alloc::boxed::Box; use core::{ + alloc::AllocError, marker::{PhantomData, Unsize}, mem::{ManuallyDrop, MaybeUninit}, ops::{Deref, DerefMut}, @@ -149,7 +149,7 @@ unsafe impl Sync for Arc {} impl Arc { /// Constructs a new reference counted instance of `T`. - pub fn try_new(contents: T) -> Result { + pub fn try_new(contents: T) -> Result { // INVARIANT: The refcount is initialised to a non-zero value. let value =3D ArcInner { // SAFETY: There are no safety requirements for this FFI call. @@ -469,7 +469,7 @@ pub struct UniqueArc { impl UniqueArc { /// Tries to allocate a new [`UniqueArc`] instance. - pub fn try_new(value: T) -> Result { + pub fn try_new(value: T) -> Result { Ok(Self { // INVARIANT: The newly-created object has a ref-count of 1. inner: Arc::try_new(value)?, @@ -477,7 +477,7 @@ impl UniqueArc { } /// Tries to allocate a new [`UniqueArc`] instance whose contents are = not initialised yet. - pub fn try_new_uninit() -> Result>> { + pub fn try_new_uninit() -> Result>, AllocErro= r> { Ok(UniqueArc::> { // INVARIANT: The newly-created object has a ref-count of 1. inner: Arc::try_new(MaybeUninit::uninit())?, -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 BB97DC7619A for ; Sat, 8 Apr 2023 12:26:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230327AbjDHM0H (ORCPT ); Sat, 8 Apr 2023 08:26:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32790 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230099AbjDHM0A (ORCPT ); Sat, 8 Apr 2023 08:26:00 -0400 Received: from mail-4322.protonmail.ch (mail-4322.protonmail.ch [185.70.43.22]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 750A9EF92 for ; Sat, 8 Apr 2023 05:25:43 -0700 (PDT) Date: Sat, 08 Apr 2023 12:25:34 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956741; x=1681215941; bh=35ec0Ze6x4vGPDCyxTq1eqzjMeEQtTPCRJPMgIkdSpQ=; 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=FYV5X6kKzH5aJLDgjemr4GztE2oe4Czvvz/JEScQv86bVFwyj0bZQ1YRQ1hXChD9m 3TfJzwTozZAHgbsWWOZFmPzRq+oxCGxUubp6HDE1DA/kfD2Jl3me0k1jwGXVMFL7z1 G3PtJmyAHAvFh4bu8fmOqU6fUhvBZ4zTl2OnBlgsn5wTU0dbtv4rMv8j6Hgx+MG3iv /jmRBJoVztPeM8++iv/hgDoghU2IlJTC/z5XU/5+0xPRd8G9p/+5WdM5jBE9tJkzxm bWSk1b7oP1fY8hLYYx7rVrfQl3Efnj57NMVrR1orrmdGJfkmE2/0WKmBJ1K/XEuJWK usrgK6JiuE8fg== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Wedson Almeida Filho , Andreas Hindborg , Alice Ryhl Subject: [PATCH v7 04/15] rust: sync: add `assume_init` to `UniqueArc` Message-ID: <20230408122429.1103522-5-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Adds the `assume_init` function to `UniqueArc>` that unsafely assumes the value to be initialized and yields a value of type `UniqueArc`. This function is used when manually initializing the pointee of an `UniqueArc`. Signed-off-by: Benno Lossin Reviewed-by: Wedson Almeida Filho Reviewed-by: Andreas Hindborg Reviewed-by: Alice Ryhl --- rust/kernel/sync/arc.rs | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index aa7135f0f238..eee7008e5e3e 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -489,6 +489,17 @@ impl UniqueArc> { /// Converts a `UniqueArc>` into a `UniqueArc` by wr= iting a value into it. pub fn write(mut self, value: T) -> UniqueArc { self.deref_mut().write(value); + // SAFETY: We just wrote the value to be initialized. + unsafe { self.assume_init() } + } + + /// Unsafely assume that `self` is initialized. + /// + /// # Safety + /// + /// The caller guarantees that the value behind this pointer has been = initialized. It is + /// *immediate* UB to call this when the value is not initialized. + pub unsafe fn assume_init(self) -> UniqueArc { let inner =3D ManuallyDrop::new(self).inner.ptr; UniqueArc { // SAFETY: The new `Arc` is taking over `ptr` from `self.inner= ` (which won't be -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 3B0DDC77B70 for ; Sat, 8 Apr 2023 12:26:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229908AbjDHM0n (ORCPT ); Sat, 8 Apr 2023 08:26:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34084 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230255AbjDHM0i (ORCPT ); Sat, 8 Apr 2023 08:26:38 -0400 Received: from mail-40134.protonmail.ch (mail-40134.protonmail.ch [185.70.40.134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F0A3113C0 for ; Sat, 8 Apr 2023 05:26:14 -0700 (PDT) Date: Sat, 08 Apr 2023 12:25:39 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956752; x=1681215952; bh=7rH6H6G+ATzJ5NdhnHFFoHIa5Qvd43Dus1uGWQ71zqY=; 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=wYbDYJmraPxCNtugfl+8EK4ojUD3Ko0hK6aHHcOlLx0R9+315OfBsZnO80StwEO6Z e+z7tdr+IvLyy2OkDHyMY7VLCRqEbPJ2YbCWtRnKhwvEAgPuxl6gK8O6H5p3PwuBg9 EcSz2h+L4QvVhF3wI7W28D2bNfDzrPi/B/kVMHjEksLKrpwmCkiOc1JJV0ZGs9GJpe MeYi2OeYZyw2OqmwL7jIJJ7jZwmCQTjsJs+cXVAPaN0Dt4UUiTnzV13VPhWLY1Tpct VZ2A97rSNk2LxUJ2S+YQaqJAPj5oxBNgTYC3miw+8jf9UmXRHijjf5QQ03P3JckqvD 97JWFxJ34j1NQ== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg 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 v7 05/15] rust: types: add `Opaque::raw_get` Message-ID: <20230408122429.1103522-6-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" This function mirrors `UnsafeCell::raw_get`. It avoids creating a reference and allows solely using raw pointers. The `pin-init` API will be using this, since uninitialized memory requires raw pointers. Signed-off-by: Benno Lossin Reviewed-by: Gary Guo Reviewed-by: Andreas Hindborg Reviewed-by: Alice Ryhl --- rust/kernel/types.rs | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs index 9d0fdbc55843..ff2b2fac951d 100644 --- a/rust/kernel/types.rs +++ b/rust/kernel/types.rs @@ -238,6 +238,14 @@ impl Opaque { pub fn get(&self) -> *mut T { UnsafeCell::raw_get(self.0.as_ptr()) } + + /// Gets the value behind `this`. + /// + /// This function is useful to get access to the value without creatin= g intermediate + /// references. + pub const fn raw_get(this: *const Self) -> *mut T { + UnsafeCell::raw_get(this.cast::>()) + } } /// A sum type that always holds either a value of type `L` or `R`. -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 03951C77B73 for ; Sat, 8 Apr 2023 12:26:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230361AbjDHM0s (ORCPT ); Sat, 8 Apr 2023 08:26:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230170AbjDHM0k (ORCPT ); Sat, 8 Apr 2023 08:26:40 -0400 Received: from mail-40134.protonmail.ch (mail-40134.protonmail.ch [185.70.40.134]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 171F4AF3F for ; Sat, 8 Apr 2023 05:26:16 -0700 (PDT) Date: Sat, 08 Apr 2023 12:25:45 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956754; x=1681215954; bh=VX/VWyHv56kwfDu4DNgq2aM6/hHa/tkwsMmN9X0A56g=; 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=xqxx7sW0xag15AlJIA1Er2w51SZh2wo8rSgU+pEme/QMVZvX4KEkV3pK8trXS3Lip sXeDy4BLYr29xuchuVaCtKR+7/etQZbm9RFLBvRRD83cTh33EwSELQjRFVFAeRVs92 QCh4dJcLvMAy3Qqjfl53AJ8Ol/nfKX/+mIPRbIVDSEBqXhQOXwYR13W7k9k7qHRGH/ fdka0o3AOZS29B8ztmptV/ftA2L4asL5fqb5+bn8Cs7e7SbkSg9SzvCMod5nqYz12J N9VQdUGDhDfI68lnQa9Zwlo++HlYYnzGJ6Dl3+6sdu/QL4dCHr3dJIBRWh0JP0P7hY hLSWjTA3WqJ2g== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Alice Ryhl , Andreas Hindborg Subject: [PATCH v7 06/15] rust: add pin-init API core Message-ID: <20230408122429.1103522-7-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" This API is used to facilitate safe pinned initialization of structs. It replaces cumbersome `unsafe` manual initialization with elegant safe macro invocations. Due to the size of this change it has been split into six commits: 1. This commit introducing the basic public interface: traits and functions to represent and create initializers. 2. Adds the `#[pin_data]`, `pin_init!`, `try_pin_init!`, `init!` and `try_init!` macros along with their internal types. 3. Adds the `InPlaceInit` trait that allows using an initializer to create an object inside of a `Box` and other smart pointers. 4. Adds the `PinnedDrop` trait and adds macro support for it in the `#[pin_data]` macro. 5. Adds the `stack_pin_init!` macro allowing to pin-initialize a struct on the stack. 6. Adds the `Zeroable` trait and `init::zeroed` function to initialize types that have `0x00` in all bytes as a valid bit pattern. -- In this section the problem that the new pin-init API solves is outlined. This message describes the entirety of the API, not just the parts introduced in this commit. For a more granular explanation and additional information on pinning and this issue, view [1]. Pinning is Rust's way of enforcing the address stability of a value. When a value gets pinned it will be impossible for safe code to move it to another location. This is done by wrapping pointers to said object with `Pin

`. This wrapper prevents safe code from creating mutable references to the object, preventing mutable access, which is needed to move the value. `Pin

` provides `unsafe` functions to circumvent this and allow modifications regardless. It is then the programmer's responsibility to uphold the pinning guarantee. Many kernel data structures require a stable address, because there are foreign pointers to them which would get invalidated by moving the structure. Since these data structures are usually embedded in structs to use them, this pinning property propagates to the container struct. Resulting in most structs in both Rust and C code needing to be pinned. So if we want to have a `mutex` field in a Rust struct, this struct also needs to be pinned, because a `mutex` contains a `list_head`. Additionally initializing a `list_head` requires already having the final memory location available, because it is initialized by pointing it to itself. But this presents another challenge in Rust: values have to be initialized at all times. There is the `MaybeUninit` wrapper type, which allows handling uninitialized memory, but this requires using the `unsafe` raw pointers and a casting the type to the initialized variant. This problem gets exacerbated when considering encapsulation and the normal safety requirements of Rust code. The fields of the Rust `Mutex` should not be accessible to normal driver code. After all if anyone can modify the fields, there is no way to ensure the invariants of the `Mutex` are upheld. But if the fields are inaccessible, then initialization of a `Mutex` needs to be somehow achieved via a function or a macro. Because the `Mutex` must be pinned in memory, the function cannot return it by value. It also cannot allocate a `Box` to put the `Mutex` into, because that is an unnecessary allocation and indirection which would hurt performance. The solution in the rust tree (e.g. this commit: [2]) that is replaced by this API is to split this function into two parts: 1. A `new` function that returns a partially initialized `Mutex`, 2. An `init` function that requires the `Mutex` to be pinned and that fully initializes the `Mutex`. Both of these functions have to be marked `unsafe`, since a call to `new` needs to be accompanied with a call to `init`, otherwise using the `Mutex` could result in UB. And because calling `init` twice also is not safe. While `Mutex` initialization cannot fail, other structs might also have to allocate memory, which would result in conditional successful initialization requiring even more manual accommodation work. Combine this with the problem of pin-projections -- the way of accessing fields of a pinned struct -- which also have an `unsafe` API, pinned initialization is riddled with `unsafe` resulting in very poor ergonomics. Not only that, but also having to call two functions possibly multiple lines apart makes it very easy to forget it outright or during refactoring. Here is an example of the current way of initializing a struct with two synchronization primitives (see [3] for the full example): struct SharedState { state_changed: CondVar, inner: Mutex, } impl SharedState { fn try_new() -> Result> { let mut state =3D Pin::from(UniqueArc::try_new(Self { // SAFETY: `condvar_init!` is called below. state_changed: unsafe { CondVar::new() }, // SAFETY: `mutex_init!` is called below. inner: unsafe { Mutex::new(SharedStateInner { token_count: 0 }) }, })?); // SAFETY: `state_changed` is pinned when `state` is. let pinned =3D unsafe { state.as_mut().map_unchecked_mut(|s| &mut s.state_changed) }; kernel::condvar_init!(pinned, "SharedState::state_changed"); // SAFETY: `inner` is pinned when `state` is. let pinned =3D unsafe { state.as_mut().map_unchecked_mut(|s| &mut s.inner) }; kernel::mutex_init!(pinned, "SharedState::inner"); Ok(state.into()) } } The pin-init API of this patch solves this issue by providing a comprehensive solution comprised of macros and traits. Here is the example from above using the pin-init API: #[pin_data] struct SharedState { #[pin] state_changed: CondVar, #[pin] inner: Mutex, } impl SharedState { fn new() -> impl PinInit { pin_init!(Self { state_changed <- new_condvar!("SharedState::state_changed"), inner <- new_mutex!( SharedStateInner { token_count: 0 }, "SharedState::inner", ), }) } } Notably the way the macro is used here requires no `unsafe` and thus comes with the usual Rust promise of safe code not introducing any memory violations. Additionally it is now up to the caller of `new()` to decide the memory location of the `SharedState`. They can choose at the moment `Arc`, `Box` or the stack. -- The API has the following architecture: 1. Initializer traits `PinInit` and `Init` that act like closures. 2. Macros to create these initializer traits safely. 3. Functions to allow manually writing initializers. The initializers (an `impl PinInit`) receive a raw pointer pointing to uninitialized memory and their job is to fully initialize a `T` at that location. If initialization fails, they return an error (`E`) by value. This way of initializing cannot be safely exposed to the user, since it relies upon these properties outside of the control of the trait: - the memory location (slot) needs to be valid memory, - if initialization fails, the slot should not be read from, - the value in the slot should be pinned, so it cannot move and the memory cannot be deallocated until the value is dropped. This is why using an initializer is facilitated by another trait that ensures these requirements. These initializers can be created manually by just supplying a closure that fulfills the same safety requirements as `PinInit`. But this is an `unsafe` operation. To allow safe initializer creation, the `pin_init!` is provided along with three other variants: `try_pin_init!`, `try_init!` and `init!`. These take a modified struct initializer as a parameter and generate a closure that initializes the fields in sequence. The macros take great care in upholding the safety requirements: - A shadowed struct type is used as the return type of the closure instead of `()`. This is to prevent early returns, as these would prevent full initialization. - To ensure every field is only initialized once, a normal struct initializer is placed in unreachable code. The type checker will emit errors if a field is missing or specified multiple times. - When initializing a field fails, the whole initializer will fail and automatically drop fields that have been initialized earlier. - Only the correct initializer type is allowed for unpinned fields. You cannot use a `impl PinInit` to initialize a structurally not pinned field. To ensure the last point, an additional macro `#[pin_data]` is needed. This macro annotates the struct itself and the user specifies structurally pinned and not pinned fields. Because dropping a pinned struct is also not allowed to break the pinning invariants, another macro attribute `#[pinned_drop]` is needed. This macro is introduced in a following commit. These two macros also have mechanisms to ensure the overall safety of the API. Additionally, they utilize a combined proc-macro, declarative macro design: first a proc-macro enables the outer attribute syntax `#[...]` and does some important pre-parsing. Notably this prepares the generics such that the declarative macro can handle them using token trees. Then the actual parsing of the structure and the emission of code is handled by a declarative macro. For pin-projections the crates `pin-project` [4] and `pin-project-lite` [5] had been considered, but were ultimately rejected: - `pin-project` depends on `syn` [6] which is a very big dependency, around 50k lines of code. - `pin-project-lite` is a more reasonable 5k lines of code, but contains a very complex declarative macro to parse generics. On top of that it would require modification that would need to be maintained independently. Link: https://rust-for-linux.com/the-safe-pinned-initialization-problem [1] Link: https://github.com/Rust-for-Linux/linux/tree/0a04dc4ddd671efb87eef54d= de0fb38e9074f4be [2] Link: https://github.com/Rust-for-Linux/linux/blob/f509ede33fc10a07eba3da14= aa00302bd4b5dddd/samples/rust/rust_miscdev.rs [3] Link: https://crates.io/crates/pin-project [4] Link: https://crates.io/crates/pin-project-lite [5] Link: https://crates.io/crates/syn [6] Co-developed-by: Gary Guo Signed-off-by: Gary Guo Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Wedson Almeida Filho Reviewed-by: Andreas Hindborg --- rust/kernel/init.rs | 187 +++++++++++++++++++++++++++++++++ rust/kernel/init/__internal.rs | 33 ++++++ rust/kernel/lib.rs | 7 ++ scripts/Makefile.build | 2 +- 4 files changed, 228 insertions(+), 1 deletion(-) create mode 100644 rust/kernel/init.rs create mode 100644 rust/kernel/init/__internal.rs diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs new file mode 100644 index 000000000000..d041f0daf71e --- /dev/null +++ b/rust/kernel/init.rs @@ -0,0 +1,187 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +//! API to safely and fallibly initialize pinned `struct`s using in-place = constructors. +//! +//! It also allows in-place initialization of big `struct`s that would oth= erwise produce a stack +//! overflow. +//! +//! Most `struct`s from the [`sync`] module need to be pinned, because the= y contain self-referential +//! `struct`s from C. [Pinning][pinning] is Rust's way of ensuring data do= es not move. +//! +//! # Overview +//! +//! To initialize a `struct` with an in-place constructor you will need tw= o things: +//! - an in-place constructor, +//! - a memory location that can hold your `struct`. +//! +//! To get an in-place constructor there are generally two options: +//! - a custom function/macro returning an in-place constructor provided b= y someone else, +//! - using the unsafe function [`pin_init_from_closure()`] to manually cr= eate an initializer. +//! +//! Aside from pinned initialization, this API also supports in-place cons= truction without pinning, +//! the macros/types/functions are generally named like the pinned variant= s without the `pin` +//! prefix. +//! +//! [`sync`]: kernel::sync +//! [pinning]: https://doc.rust-lang.org/std/pin/index.html +//! [structurally pinned fields]: +//! https://doc.rust-lang.org/std/pin/index.html#pinning-is-structural= -for-field +//! [`Arc`]: crate::sync::Arc +//! [`impl PinInit`]: PinInit +//! [`impl PinInit`]: PinInit +//! [`impl Init`]: Init +//! [`Opaque`]: kernel::types::Opaque +//! [`pin_data`]: ::macros::pin_data +//! [`UniqueArc`]: kernel::sync::UniqueArc +//! [`Box`]: alloc::boxed::Box + +use core::{convert::Infallible, marker::PhantomData, mem::MaybeUninit}; + +#[doc(hidden)] +pub mod __internal; + +/// 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`]. +/// +/// Also see the [module description](self). +/// +/// # Safety +/// +/// When implementing this type you will need to take great care. Also the= re are probably very few +/// cases where a manual implementation is necessary. Use [`pin_init_from_= closure`] where possible. +/// +/// The [`PinInit::__pinned_init`] function +/// - returns `Ok(())` if it initialized every field of `slot`, +/// - returns `Err(err)` if it encountered an error and then cleaned `slot= `, this means: +/// - `slot` can be deallocated without UB occurring, +/// - `slot` does not need to be dropped, +/// - `slot` is not partially initialized. +/// - while constructing the `T` at `slot` it upholds the pinning invarian= ts of `T`. +/// +/// [`Arc`]: crate::sync::Arc +/// [`Arc::pin_init`]: crate::sync::Arc::pin_init +/// [`UniqueArc`]: kernel::sync::UniqueArc +/// [`Box`]: alloc::boxed::Box +#[must_use =3D "An initializer must be used in order to create its value."] +pub unsafe trait PinInit: Sized { + /// Initializes `slot`. + /// + /// # Safety + /// + /// - `slot` is a valid pointer to uninitialized memory. + /// - the caller does not touch `slot` when `Err` is returned, they ar= e only permitted to + /// deallocate. + /// - `slot` will not move until it is dropped, i.e. it will be pinned. + unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E>; +} + +/// 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 +/// use every function that takes it as well. +/// +/// Also see the [module description](self). +/// +/// # Safety +/// +/// When implementing this type you will need to take great care. Also the= re are probably very few +/// cases where a manual implementation is necessary. Use [`init_from_clos= ure`] where possible. +/// +/// The [`Init::__init`] function +/// - returns `Ok(())` if it initialized every field of `slot`, +/// - returns `Err(err)` if it encountered an error and then cleaned `slot= `, this means: +/// - `slot` can be deallocated without UB occurring, +/// - `slot` does not need to be dropped, +/// - `slot` is not partially initialized. +/// - while constructing the `T` at `slot` it upholds the pinning invarian= ts of `T`. +/// +/// The `__pinned_init` function from the supertrait [`PinInit`] needs to = execute the exact same +/// code as `__init`. +/// +/// Contrary to its supertype [`PinInit`] the caller is allowed to +/// move the pointee after initialization. +/// +/// [`Arc`]: crate::sync::Arc +/// [`UniqueArc`]: kernel::sync::UniqueArc +/// [`Box`]: alloc::boxed::Box +#[must_use =3D "An initializer must be used in order to create its value."] +pub unsafe trait Init: Sized { + /// Initializes `slot`. + /// + /// # Safety + /// + /// - `slot` is a valid pointer to uninitialized memory. + /// - the caller does not touch `slot` when `Err` is returned, they ar= e only permitted to + /// deallocate. + unsafe fn __init(self, slot: *mut T) -> Result<(), E>; +} + +// SAFETY: Every in-place initializer can also be used as a pin-initialize= r. +unsafe impl PinInit for I +where + I: Init, +{ + unsafe fn __pinned_init(self, slot: *mut T) -> Result<(), E> { + // SAFETY: `__init` meets the same requirements as `__pinned_init`= , except that it does not + // require `slot` to not move after init. + unsafe { self.__init(slot) } + } +} + +/// Creates a new [`PinInit`] from the given closure. +/// +/// # Safety +/// +/// The closure: +/// - returns `Ok(())` if it initialized every field of `slot`, +/// - returns `Err(err)` if it encountered an error and then cleaned `slot= `, this means: +/// - `slot` can be deallocated without UB occurring, +/// - `slot` does not need to be dropped, +/// - `slot` is not partially initialized. +/// - may assume that the `slot` does not move if `T: !Unpin`, +/// - while constructing the `T` at `slot` it upholds the pinning invarian= ts of `T`. +#[inline] +pub const unsafe fn pin_init_from_closure( + f: impl FnOnce(*mut T) -> Result<(), E>, +) -> impl PinInit { + __internal::InitClosure(f, PhantomData) +} + +/// Creates a new [`Init`] from the given closure. +/// +/// # Safety +/// +/// The closure: +/// - returns `Ok(())` if it initialized every field of `slot`, +/// - returns `Err(err)` if it encountered an error and then cleaned `slot= `, this means: +/// - `slot` can be deallocated without UB occurring, +/// - `slot` does not need to be dropped, +/// - `slot` is not partially initialized. +/// - the `slot` may move after initialization. +/// - while constructing the `T` at `slot` it upholds the pinning invarian= ts of `T`. +#[inline] +pub const unsafe fn init_from_closure( + f: impl FnOnce(*mut T) -> Result<(), E>, +) -> impl Init { + __internal::InitClosure(f, PhantomData) +} + +/// An initializer that leaves the memory uninitialized. +/// +/// The initializer is a no-op. The `slot` memory is not changed. +#[inline] +pub fn uninit() -> impl Init, E> { + // SAFETY: The memory is allowed to be uninitialized. + unsafe { init_from_closure(|_| Ok(())) } +} + +// SAFETY: Every type can be initialized by-value. +unsafe impl Init for T { + unsafe fn __init(self, slot: *mut T) -> Result<(), Infallible> { + unsafe { slot.write(self) }; + Ok(()) + } +} diff --git a/rust/kernel/init/__internal.rs b/rust/kernel/init/__internal.rs new file mode 100644 index 000000000000..08cbb5333438 --- /dev/null +++ b/rust/kernel/init/__internal.rs @@ -0,0 +1,33 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +//! This module contains API-internal items for pin-init. +//! +//! These items must not be used outside of +//! - `kernel/init.rs` +//! - `macros/pin_data.rs` +//! - `macros/pinned_drop.rs` + +use super::*; + +/// See the [nomicon] for what subtyping is. See also [this table]. +/// +/// [nomicon]: https://doc.rust-lang.org/nomicon/subtyping.html +/// [this table]: https://doc.rust-lang.org/nomicon/phantom-data.html#tabl= e-of-phantomdata-patterns +type Invariant =3D PhantomData *mut T>; + +/// This is the module-internal type implementing `PinInit` and `Init`. It= is unsafe to create this +/// type, since the closure needs to fulfill the same safety requirement a= s the +/// `__pinned_init`/`__init` functions. +pub(crate) struct InitClosure(pub(crate) F, pub(crate) In= variant<(E, T)>); + +// SAFETY: While constructing the `InitClosure`, the user promised that it= upholds the +// `__init` invariants. +unsafe impl Init for InitClosure +where + F: FnOnce(*mut T) -> Result<(), E>, +{ + #[inline] + unsafe fn __init(self, slot: *mut T) -> Result<(), E> { + (self.0)(slot) + } +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 4317b6d5f50b..821bd067151c 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -16,7 +16,9 @@ #![feature(coerce_unsized)] #![feature(core_ffi_c)] #![feature(dispatch_from_dyn)] +#![feature(explicit_generic_args_with_impl_trait)] #![feature(generic_associated_types)] +#![feature(new_uninit)] #![feature(pin_macro)] #![feature(receiver_trait)] #![feature(unsize)] @@ -26,11 +28,16 @@ #[cfg(not(CONFIG_RUST))] compile_error!("Missing kernel configuration for conditional compilation"); +#[allow(unused_extern_crates)] +// Allow proc-macros to refer to `::kernel` inside the `kernel` crate (thi= s crate). +extern crate self as kernel; + #[cfg(not(test))] #[cfg(not(testlib))] mod allocator; mod build_assert; pub mod error; +pub mod init; pub mod prelude; pub mod print; mod static_assert; diff --git a/scripts/Makefile.build b/scripts/Makefile.build index ba4102b9d94d..7aafb5f1bc53 100644 --- a/scripts/Makefile.build +++ b/scripts/Makefile.build @@ -277,7 +277,7 @@ $(obj)/%.lst: $(src)/%.c FORCE # Compile Rust sources (.rs) # ------------------------------------------------------------------------= --- -rust_allowed_features :=3D core_ffi_c,pin_macro +rust_allowed_features :=3D core_ffi_c,pin_macro,explicit_generic_args_with= _impl_trait rust_common_cmd =3D \ RUST_MODFILE=3D$(modfile) $(RUSTC_OR_CLIPPY) $(rust_flags) \ -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 61E2FC77B71 for ; Sat, 8 Apr 2023 12:26:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230267AbjDHM0p (ORCPT ); Sat, 8 Apr 2023 08:26:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33988 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229689AbjDHM0j (ORCPT ); Sat, 8 Apr 2023 08:26:39 -0400 Received: from mail-4316.protonmail.ch (mail-4316.protonmail.ch [185.70.43.16]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65A766EBA; Sat, 8 Apr 2023 05:26:15 -0700 (PDT) Date: Sat, 08 Apr 2023 12:25:51 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956754; x=1681215954; bh=9lvL8BsXMyJE9DRPXej4QZ0JmktlDAk9VuvBVnjIqPc=; 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=G76vLi6FHF767alejdEhm70BiFTbefXL5X2izV5Il1m7WwFusGYPrZVk93T5OjBBu dwoL+O2OEYE0c6h90Ty4QfY0MHzDiXIlTz+NNbHCi5k8Go1iFYvKAXXPdSlSpL5bOY SD0KWpX8CRjKithyM8b1zk4CHBAYl+n3ae1CmtEFHx8fQF45NHWWsRLchw/s4PlQDd e++BQpmKw63glVlsV9UPL3PSyP1U+dOjZURz2yRlUOwoIAntdKzcnXdOgwfIhHFgJJ 6oDNrerbMpToJ6WFgFmqFzKoz0mkJK7yiCMw5qVgQ8NZyPIfpcCEiXdwZ4IiI/Pv9c KifvRiICVy5gg== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Alice Ryhl , Andreas Hindborg Subject: [PATCH v7 07/15] rust: init: add initialization macros Message-ID: <20230408122429.1103522-8-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Add the following initializer macros: - `#[pin_data]` to annotate structurally pinned fields of structs, needed for `pin_init!` and `try_pin_init!` to select the correct initializer of fields. - `pin_init!` create a pin-initializer for a struct with the `Infallible` error type. - `try_pin_init!` create a pin-initializer for a struct with a custom error type (`kernel::error::Error` is the default). - `init!` create an in-place-initializer for a struct with the `Infallible` error type. - `try_init!` create an in-place-initializer for a struct with a custom error type (`kernel::error::Error` is the default). Also add their needed internal helper traits and structs. Co-developed-by: Gary Guo Signed-off-by: Gary Guo Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg --- rust/kernel/init.rs | 807 ++++++++++++++++++++++++++++++++- rust/kernel/init/__internal.rs | 130 ++++++ rust/kernel/init/macros.rs | 707 +++++++++++++++++++++++++++++ rust/macros/lib.rs | 29 ++ rust/macros/pin_data.rs | 79 ++++ rust/macros/quote.rs | 2 - 6 files changed, 1747 insertions(+), 7 deletions(-) create mode 100644 rust/kernel/init/macros.rs create mode 100644 rust/macros/pin_data.rs diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index d041f0daf71e..ecef0376d726 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -14,7 +14,8 @@ //! - an in-place constructor, //! - a memory location that can hold your `struct`. //! -//! To get an in-place constructor there are generally two options: +//! To get an in-place constructor there are generally three options: +//! - directly creating an in-place constructor using the [`pin_init!`] ma= cro, //! - a custom function/macro returning an in-place constructor provided b= y someone else, //! - using the unsafe function [`pin_init_from_closure()`] to manually cr= eate an initializer. //! @@ -22,6 +23,87 @@ //! the macros/types/functions are generally named like the pinned variant= s without the `pin` //! prefix. //! +//! # Examples +//! +//! ## Using the [`pin_init!`] macro +//! +//! If you want to use [`PinInit`], then you will have to annotate your `s= truct` with +//! `#[`[`pin_data`]`]`. It is a macro that uses `#[pin]` as a marker for +//! [structurally pinned fields]. After doing this, you can then create an= in-place constructor via +//! [`pin_init!`]. The syntax is almost the same as normal `struct` initia= lizers. The difference is +//! that you need to write `<-` instead of `:` for fields that you want to= initialize in-place. +//! +//! ```rust +//! # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +//! use kernel::{prelude::*, sync::Mutex, new_mutex}; +//! # use core::pin::Pin; +//! #[pin_data] +//! struct Foo { +//! #[pin] +//! a: Mutex, +//! b: u32, +//! } +//! +//! let foo =3D pin_init!(Foo { +//! a <- new_mutex!(42, "Foo::a"), +//! b: 24, +//! }); +//! ``` +//! +//! `foo` now is of the type [`impl PinInit`]. We can now use any sma= rt pointer that we like +//! (or just the stack) to actually initialize a `Foo`: +//! +//! ```rust +//! # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +//! # use kernel::{prelude::*, sync::Mutex, new_mutex}; +//! # use core::pin::Pin; +//! # #[pin_data] +//! # struct Foo { +//! # #[pin] +//! # a: Mutex, +//! # b: u32, +//! # } +//! # let foo =3D pin_init!(Foo { +//! # a <- new_mutex!(42, "Foo::a"), +//! # b: 24, +//! # }); +//! let foo: Result>> =3D Box::pin_init(foo); +//! ``` +//! +//! For more information see the [`pin_init!`] macro. +//! +//! ## Using a custom function/macro that returns an initializer +//! +//! Many types from the kernel supply a function/macro that returns an ini= tializer, because the +//! above method only works for types where you can access the fields. +//! +//! ```rust +//! # use kernel::{new_mutex, sync::{Arc, Mutex}}; +//! let mtx: Result>> =3D Arc::pin_init(new_mutex!(42, "e= xample::mtx")); +//! ``` +//! +//! To declare an init macro/function you just return an [`impl PinInit`]: +//! +//! ```rust +//! # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +//! # use kernel::{sync::Mutex, prelude::*, new_mutex, init::PinInit, try_= pin_init}; +//! #[pin_data] +//! struct DriverData { +//! #[pin] +//! status: Mutex, +//! buffer: Box<[u8; 1_000_000]>, +//! } +//! +//! impl DriverData { +//! fn new() -> impl PinInit { +//! try_pin_init!(Self { +//! status <- new_mutex!(0, "DriverData::status"), +//! buffer: Box::init(kernel::init::zeroed())?, +//! }) +//! } +//! } +//! ``` +//! //! [`sync`]: kernel::sync //! [pinning]: https://doc.rust-lang.org/std/pin/index.html //! [structurally pinned fields]: @@ -33,12 +115,729 @@ //! [`Opaque`]: kernel::types::Opaque //! [`pin_data`]: ::macros::pin_data //! [`UniqueArc`]: kernel::sync::UniqueArc -//! [`Box`]: alloc::boxed::Box -use core::{convert::Infallible, marker::PhantomData, mem::MaybeUninit}; +use alloc::boxed::Box; +use core::{cell::Cell, convert::Infallible, marker::PhantomData, mem::Mayb= eUninit, ptr}; #[doc(hidden)] pub mod __internal; +#[doc(hidden)] +pub mod macros; + +/// Construct an in-place, pinned initializer for `struct`s. +/// +/// This macro defaults the error to [`Infallible`]. If you need [`Error`]= , then use +/// [`try_pin_init!`]. +/// +/// The syntax is almost identical to that of a normal `struct` initialize= r: +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, macros::pin_data, init::*}; +/// # use core::pin::Pin; +/// #[pin_data] +/// struct Foo { +/// a: usize, +/// b: Bar, +/// } +/// +/// #[pin_data] +/// struct Bar { +/// x: u32, +/// } +/// +/// # fn demo() -> impl PinInit { +/// let a =3D 42; +/// +/// let initializer =3D pin_init!(Foo { +/// a, +/// b: Bar { +/// x: 64, +/// }, +/// }); +/// # initializer } +/// # Box::pin_init(demo()).unwrap(); +/// ``` +/// +/// Arbitrary Rust expressions can be used to set the value of a variable. +/// +/// The fields are initialized in the order that they appear in the initia= lizer. So it is possible +/// to read already initialized fields using raw pointers. +/// +/// IMPORTANT: You are not allowed to create references to fields of the s= truct inside of the +/// initializer. +/// +/// # Init-functions +/// +/// When working with this API it is often desired to let others construct= your types without +/// giving access to all fields. This is where you would normally write a = plain function `new` +/// that would return a new instance of your type. With this API that is a= lso possible. +/// However, there are a few extra things to keep in mind. +/// +/// To create an initializer function, simply declare it like this: +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, prelude::*, init::*}; +/// # use core::pin::Pin; +/// # #[pin_data] +/// # struct Foo { +/// # a: usize, +/// # b: Bar, +/// # } +/// # #[pin_data] +/// # struct Bar { +/// # x: u32, +/// # } +/// impl Foo { +/// fn new() -> impl PinInit { +/// pin_init!(Self { +/// a: 42, +/// b: Bar { +/// x: 64, +/// }, +/// }) +/// } +/// } +/// ``` +/// +/// Users of `Foo` can now create it like this: +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, macros::pin_data, init::*}; +/// # use core::pin::Pin; +/// # #[pin_data] +/// # struct Foo { +/// # a: usize, +/// # b: Bar, +/// # } +/// # #[pin_data] +/// # struct Bar { +/// # x: u32, +/// # } +/// # impl Foo { +/// # fn new() -> impl PinInit { +/// # pin_init!(Self { +/// # a: 42, +/// # b: Bar { +/// # x: 64, +/// # }, +/// # }) +/// # } +/// # } +/// let foo =3D Box::pin_init(Foo::new()); +/// ``` +/// +/// They can also easily embed it into their own `struct`s: +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, macros::pin_data, init::*}; +/// # use core::pin::Pin; +/// # #[pin_data] +/// # struct Foo { +/// # a: usize, +/// # b: Bar, +/// # } +/// # #[pin_data] +/// # struct Bar { +/// # x: u32, +/// # } +/// # impl Foo { +/// # fn new() -> impl PinInit { +/// # pin_init!(Self { +/// # a: 42, +/// # b: Bar { +/// # x: 64, +/// # }, +/// # }) +/// # } +/// # } +/// #[pin_data] +/// struct FooContainer { +/// #[pin] +/// foo1: Foo, +/// #[pin] +/// foo2: Foo, +/// other: u32, +/// } +/// +/// impl FooContainer { +/// fn new(other: u32) -> impl PinInit { +/// pin_init!(Self { +/// foo1 <- Foo::new(), +/// foo2 <- Foo::new(), +/// other, +/// }) +/// } +/// } +/// ``` +/// +/// Here we see that when using `pin_init!` with `PinInit`, one needs to w= rite `<-` instead of `:`. +/// This signifies that the given field is initialized in-place. As with `= struct` initializers, just +/// writing the field (in this case `other`) without `:` or `<-` means `ot= her: other,`. +/// +/// # Syntax +/// +/// As already mentioned in the examples above, inside of `pin_init!` a `s= truct` initializer with +/// the following modifications is expected: +/// - Fields that you want to initialize in-place have to use `<-` instead= of `:`. +/// - In front of the initializer you can write `&this in` to have access = to a [`NonNull`] +/// pointer named `this` inside of the initializer. +/// +/// For instance: +/// +/// ```rust +/// # use kernel::pin_init; +/// # use macros::pin_data; +/// # use core::{ptr::addr_of_mut, marker::PhantomPinned}; +/// #[pin_data] +/// struct Buf { +/// // `ptr` points into `buf`. +/// ptr: *mut u8, +/// buf: [u8; 64], +/// #[pin] +/// pin: PhantomPinned, +/// } +/// pin_init!(&this in Buf { +/// buf: [0; 64], +/// ptr: unsafe { addr_of_mut!((*this.as_ptr()).buf).cast() }, +/// pin: PhantomPinned, +/// }); +/// ``` +/// +/// [`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] +macro_rules! pin_init { + ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { + $($fields:tt)* + }) =3D> { + $crate::try_pin_init!( + @this($($this)?), + @typ($t $(::<$($generics),*>)?), + @fields($($fields)*), + @error(::core::convert::Infallible), + ) + }; +} + +/// Construct an in-place, fallible pinned initializer for `struct`s. +/// +/// If the initialization can complete without error (or [`Infallible`]), = then use [`pin_init!`]. +/// +/// You can use the `?` operator or use `return Err(err)` inside the initi= alizer to stop +/// initialization and return the error. +/// +/// IMPORTANT: if you have `unsafe` code inside of the initializer you hav= e to ensure that when +/// initialization fails, the memory can be safely deallocated without any= further modifications. +/// +/// This macro defaults the error to [`Error`]. +/// +/// The syntax is identical to [`pin_init!`] with the following exception:= you can append `? $type` +/// after the `struct` initializer to specify the error type you want to u= se. +/// +/// # Examples +/// +/// ```rust +/// # #![feature(new_uninit)] +/// use kernel::{init::{self, PinInit}, error::Error}; +/// #[pin_data] +/// struct BigBuf { +/// big: Box<[u8; 1024 * 1024 * 1024]>, +/// small: [u8; 1024 * 1024], +/// ptr: *mut u8, +/// } +/// +/// impl BigBuf { +/// fn new() -> impl PinInit { +/// try_pin_init!(Self { +/// big: Box::init(init::zeroed())?, +/// small: [0; 1024 * 1024], +/// ptr: core::ptr::null_mut(), +/// }? Error) +/// } +/// } +/// ``` +/// +/// [`Error`]: kernel::error::Error +// For a detailed example of how this macro works, see the module document= ation of the hidden +// module `__internal` inside of `init/__internal.rs`. +#[macro_export] +macro_rules! try_pin_init { + ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { + $($fields:tt)* + }) =3D> { + $crate::try_pin_init!( + @this($($this)?), + @typ($t $(::<$($generics),*>)? ), + @fields($($fields)*), + @error($crate::error::Error), + ) + }; + ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { + $($fields:tt)* + }? $err:ty) =3D> { + $crate::try_pin_init!( + @this($($this)?), + @typ($t $(::<$($generics),*>)? ), + @fields($($fields)*), + @error($err), + ) + }; + ( + @this($($this:ident)?), + @typ($t:ident $(::<$($generics:ty),*>)?), + @fields($($fields:tt)*), + @error($err:ty), + ) =3D> {{ + // We do not want to allow arbitrary returns, so we declare this t= ype as the `Ok` return + // type and shadow it later when we insert the arbitrary user code= . That way there will be + // no possibility of returning without `unsafe`. + struct __InitOk; + // Get the pin data from the supplied type. + let data =3D unsafe { + use $crate::init::__internal::HasPinData; + $t$(::<$($generics),*>)?::__pin_data() + }; + // Ensure that `data` really is of type `PinData` and help with ty= pe inference: + let init =3D $crate::init::__internal::PinData::make_closure::<_, = __InitOk, $err>( + data, + move |slot| { + { + // Shadow the structure so it cannot be used to return= early. + struct __InitOk; + // Create the `this` so it can be referenced by the us= er inside of the + // expressions creating the individual fields. + $(let $this =3D unsafe { ::core::ptr::NonNull::new_unc= hecked(slot) };)? + // Initialize every field. + $crate::try_pin_init!(init_slot: + @data(data), + @slot(slot), + @munch_fields($($fields)*,), + ); + // We use unreachable code to ensure that all fields h= ave been mentioned exactly + // once, this struct initializer will still be type-ch= ecked and complain with a + // very natural error message if a field is forgotten/= mentioned more than once. + #[allow(unreachable_code, clippy::diverging_sub_expres= sion)] + if false { + $crate::try_pin_init!(make_initializer: + @slot(slot), + @type_name($t), + @munch_fields($($fields)*,), + @acc(), + ); + } + // Forget all guards, since initialization was a succe= ss. + $crate::try_pin_init!(forget_guards: + @munch_fields($($fields)*,), + ); + } + Ok(__InitOk) + } + ); + let init =3D move |slot| -> ::core::result::Result<(), $err> { + init(slot).map(|__InitOk| ()) + }; + let init =3D unsafe { $crate::init::pin_init_from_closure::<_, $er= r>(init) }; + init + }}; + (init_slot: + @data($data:ident), + @slot($slot:ident), + @munch_fields($(,)?), + ) =3D> { + // Endpoint of munching, no fields are left. + }; + (init_slot: + @data($data:ident), + @slot($slot:ident), + // In-place initialization syntax. + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + ) =3D> { + let $field =3D $val; + // Call the initializer. + // + // SAFETY: `slot` is valid, because we are inside of an initialize= r closure, we + // return when an error/panic occurs. + // We also use the `data` to require the correct trait (`Init` or = `PinInit`) for `$field`. + unsafe { $data.$field(::core::ptr::addr_of_mut!((*$slot).$field), = $field)? }; + // Create the drop guard. + // + // We only give access to `&DropGuard`, so it cannot be forgotten = via safe code. + // + // SAFETY: We forget the guard later when initialization has succe= eded. + let $field =3D &unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_= mut!((*$slot).$field)) + }; + + $crate::try_pin_init!(init_slot: + @data($data), + @slot($slot), + @munch_fields($($rest)*), + ); + }; + (init_slot: + @data($data:ident), + @slot($slot:ident), + // Direct value init, this is safe for every field. + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + ) =3D> { + $(let $field =3D $val;)? + // Initialize the field. + // + // SAFETY: The memory at `slot` is uninitialized. + unsafe { ::core::ptr::write(::core::ptr::addr_of_mut!((*$slot).$fi= eld), $field) }; + // Create the drop guard: + // + // We only give access to `&DropGuard`, so it cannot be accidental= ly forgotten. + // + // SAFETY: We forget the guard later when initialization has succe= eded. + let $field =3D &unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_= mut!((*$slot).$field)) + }; + + $crate::try_pin_init!(init_slot: + @data($data), + @slot($slot), + @munch_fields($($rest)*), + ); + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($(,)?), + @acc($($acc:tt)*), + ) =3D> { + // Endpoint, nothing more to munch, create the initializer. + // Since we are in the `if false` branch, this will never get exec= uted. We abuse `slot` to + // get the correct type inference here: + unsafe { + ::core::ptr::write($slot, $t { + $($acc)* + }); + } + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + @acc($($acc:tt)*), + ) =3D> { + $crate::try_pin_init!(make_initializer: + @slot($slot), + @type_name($t), + @munch_fields($($rest)*), + @acc($($acc)* $field: ::core::panic!(),), + ); + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + @acc($($acc:tt)*), + ) =3D> { + $crate::try_pin_init!(make_initializer: + @slot($slot), + @type_name($t), + @munch_fields($($rest)*), + @acc($($acc)* $field: ::core::panic!(),), + ); + }; + (forget_guards: + @munch_fields($(,)?), + ) =3D> { + // Munching finished. + }; + (forget_guards: + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + ) =3D> { + unsafe { $crate::init::__internal::DropGuard::forget($field) }; + + $crate::try_pin_init!(forget_guards: + @munch_fields($($rest)*), + ); + }; + (forget_guards: + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + ) =3D> { + unsafe { $crate::init::__internal::DropGuard::forget($field) }; + + $crate::try_pin_init!(forget_guards: + @munch_fields($($rest)*), + ); + }; +} + +/// Construct an in-place initializer for `struct`s. +/// +/// This macro defaults the error to [`Infallible`]. If you need [`Error`]= , then use +/// [`try_init!`]. +/// +/// The syntax is identical to [`pin_init!`] and its safety caveats also a= pply: +/// - `unsafe` code must guarantee either full initialization or return an= error and allow +/// deallocation of the memory. +/// - the fields are initialized in the order given in the initializer. +/// - no references to fields are allowed to be created inside of the init= ializer. +/// +/// This initializer is for initializing data in-place that might later be= moved. If you want to +/// pin-initialize, use [`pin_init!`]. +/// +/// [`Error`]: kernel::error::Error +// For a detailed example of how this macro works, see the module document= ation of the hidden +// module `__internal` inside of `init/__internal.rs`. +#[macro_export] +macro_rules! init { + ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { + $($fields:tt)* + }) =3D> { + $crate::try_init!( + @this($($this)?), + @typ($t $(::<$($generics),*>)?), + @fields($($fields)*), + @error(::core::convert::Infallible), + ) + } +} + +/// Construct an in-place fallible initializer for `struct`s. +/// +/// This macro defaults the error to [`Error`]. If you need [`Infallible`]= , then use +/// [`init!`]. +/// +/// The syntax is identical to [`try_pin_init!`]. If you want to specify a= custom error, +/// append `? $type` after the `struct` initializer. +/// The safety caveats from [`try_pin_init!`] also apply: +/// - `unsafe` code must guarantee either full initialization or return an= error and allow +/// deallocation of the memory. +/// - the fields are initialized in the order given in the initializer. +/// - no references to fields are allowed to be created inside of the init= ializer. +/// +/// # Examples +/// +/// ```rust +/// use kernel::{init::PinInit, error::Error, InPlaceInit}; +/// struct BigBuf { +/// big: Box<[u8; 1024 * 1024 * 1024]>, +/// small: [u8; 1024 * 1024], +/// } +/// +/// impl BigBuf { +/// fn new() -> impl Init { +/// try_init!(Self { +/// big: Box::init(zeroed())?, +/// small: [0; 1024 * 1024], +/// }? Error) +/// } +/// } +/// ``` +/// +/// [`Error`]: kernel::error::Error +// For a detailed example of how this macro works, see the module document= ation of the hidden +// module `__internal` inside of `init/__internal.rs`. +#[macro_export] +macro_rules! try_init { + ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { + $($fields:tt)* + }) =3D> { + $crate::try_init!( + @this($($this)?), + @typ($t $(::<$($generics),*>)?), + @fields($($fields)*), + @error($crate::error::Error), + ) + }; + ($(&$this:ident in)? $t:ident $(::<$($generics:ty),* $(,)?>)? { + $($fields:tt)* + }? $err:ty) =3D> { + $crate::try_init!( + @this($($this)?), + @typ($t $(::<$($generics),*>)?), + @fields($($fields)*), + @error($err), + ) + }; + ( + @this($($this:ident)?), + @typ($t:ident $(::<$($generics:ty),*>)?), + @fields($($fields:tt)*), + @error($err:ty), + ) =3D> {{ + // We do not want to allow arbitrary returns, so we declare this t= ype as the `Ok` return + // type and shadow it later when we insert the arbitrary user code= . That way there will be + // no possibility of returning without `unsafe`. + struct __InitOk; + // Get the init data from the supplied type. + let data =3D unsafe { + use $crate::init::__internal::HasInitData; + $t$(::<$($generics),*>)?::__init_data() + }; + // Ensure that `data` really is of type `InitData` and help with t= ype inference: + let init =3D $crate::init::__internal::InitData::make_closure::<_,= __InitOk, $err>( + data, + move |slot| { + { + // Shadow the structure so it cannot be used to return= early. + struct __InitOk; + // Create the `this` so it can be referenced by the us= er inside of the + // expressions creating the individual fields. + $(let $this =3D unsafe { ::core::ptr::NonNull::new_unc= hecked(slot) };)? + // Initialize every field. + $crate::try_init!(init_slot: + @slot(slot), + @munch_fields($($fields)*,), + ); + // We use unreachable code to ensure that all fields h= ave been mentioned exactly + // once, this struct initializer will still be type-ch= ecked and complain with a + // very natural error message if a field is forgotten/= mentioned more than once. + #[allow(unreachable_code, clippy::diverging_sub_expres= sion)] + if false { + $crate::try_init!(make_initializer: + @slot(slot), + @type_name($t), + @munch_fields($($fields)*,), + @acc(), + ); + } + // Forget all guards, since initialization was a succe= ss. + $crate::try_init!(forget_guards: + @munch_fields($($fields)*,), + ); + } + Ok(__InitOk) + } + ); + let init =3D move |slot| -> ::core::result::Result<(), $err> { + init(slot).map(|__InitOk| ()) + }; + let init =3D unsafe { $crate::init::init_from_closure::<_, $err>(i= nit) }; + init + }}; + (init_slot: + @slot($slot:ident), + @munch_fields( $(,)?), + ) =3D> { + // Endpoint of munching, no fields are left. + }; + (init_slot: + @slot($slot:ident), + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + ) =3D> { + let $field =3D $val; + // Call the initializer. + // + // SAFETY: `slot` is valid, because we are inside of an initialize= r closure, we + // return when an error/panic occurs. + unsafe { + $crate::init::Init::__init($field, ::core::ptr::addr_of_mut!((= *$slot).$field))?; + } + // Create the drop guard. + // + // We only give access to `&DropGuard`, so it cannot be accidental= ly forgotten. + // + // SAFETY: We forget the guard later when initialization has succe= eded. + let $field =3D &unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_= mut!((*$slot).$field)) + }; + + $crate::try_init!(init_slot: + @slot($slot), + @munch_fields($($rest)*), + ); + }; + (init_slot: + @slot($slot:ident), + // Direct value init. + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + ) =3D> { + $(let $field =3D $val;)? + // Call the initializer. + // + // SAFETY: The memory at `slot` is uninitialized. + unsafe { ::core::ptr::write(::core::ptr::addr_of_mut!((*$slot).$fi= eld), $field) }; + // Create the drop guard. + // + // We only give access to `&DropGuard`, so it cannot be accidental= ly forgotten. + // + // SAFETY: We forget the guard later when initialization has succe= eded. + let $field =3D &unsafe { + $crate::init::__internal::DropGuard::new(::core::ptr::addr_of_= mut!((*$slot).$field)) + }; + + $crate::try_init!(init_slot: + @slot($slot), + @munch_fields($($rest)*), + ); + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields( $(,)?), + @acc($($acc:tt)*), + ) =3D> { + // Endpoint, nothing more to munch, create the initializer. + // Since we are in the `if false` branch, this will never get exec= uted. We abuse `slot` to + // get the correct type inference here: + unsafe { + ::core::ptr::write($slot, $t { + $($acc)* + }); + } + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + @acc($($acc:tt)*), + ) =3D> { + $crate::try_init!(make_initializer: + @slot($slot), + @type_name($t), + @munch_fields($($rest)*), + @acc($($acc)*$field: ::core::panic!(),), + ); + }; + (make_initializer: + @slot($slot:ident), + @type_name($t:ident), + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + @acc($($acc:tt)*), + ) =3D> { + $crate::try_init!(make_initializer: + @slot($slot), + @type_name($t), + @munch_fields($($rest)*), + @acc($($acc)*$field: ::core::panic!(),), + ); + }; + (forget_guards: + @munch_fields($(,)?), + ) =3D> { + // Munching finished. + }; + (forget_guards: + @munch_fields($field:ident <- $val:expr, $($rest:tt)*), + ) =3D> { + unsafe { $crate::init::__internal::DropGuard::forget($field) }; + + $crate::try_init!(forget_guards: + @munch_fields($($rest)*), + ); + }; + (forget_guards: + @munch_fields($field:ident $(: $val:expr)?, $($rest:tt)*), + ) =3D> { + unsafe { $crate::init::__internal::DropGuard::forget($field) }; + + $crate::try_init!(forget_guards: + @munch_fields($($rest)*), + ); + }; +} /// A pin-initializer for the type `T`. /// @@ -63,7 +862,6 @@ pub mod __internal; /// [`Arc`]: crate::sync::Arc /// [`Arc::pin_init`]: crate::sync::Arc::pin_init /// [`UniqueArc`]: kernel::sync::UniqueArc -/// [`Box`]: alloc::boxed::Box #[must_use =3D "An initializer must be used in order to create its value."] pub unsafe trait PinInit: Sized { /// Initializes `slot`. @@ -106,7 +904,6 @@ pub unsafe trait PinInit: = Sized { /// /// [`Arc`]: crate::sync::Arc /// [`UniqueArc`]: kernel::sync::UniqueArc -/// [`Box`]: alloc::boxed::Box #[must_use =3D "An initializer must be used in order to create its value."] pub unsafe trait Init: Sized { /// Initializes `slot`. diff --git a/rust/kernel/init/__internal.rs b/rust/kernel/init/__internal.rs index 08cbb5333438..7aab9a8b0336 100644 --- a/rust/kernel/init/__internal.rs +++ b/rust/kernel/init/__internal.rs @@ -31,3 +31,133 @@ where (self.0)(slot) } } + +/// This trait is only implemented via the `#[pin_data]` proc-macro. It is= used to facilitate +/// the pin projections within the initializers. +/// +/// # Safety +/// +/// Only the `init` module is allowed to use this trait. +pub unsafe trait HasPinData { + type PinData: PinData; + + unsafe fn __pin_data() -> Self::PinData; +} + +/// Marker trait for pinning data of structs. +/// +/// # Safety +/// +/// Only the `init` module is allowed to use this trait. +pub unsafe trait PinData: Copy { + type Datee: ?Sized + HasPinData; + + /// Type inference helper function. + fn make_closure(self, f: F) -> F + where + F: FnOnce(*mut Self::Datee) -> Result, + { + f + } +} + +/// This trait is automatically implemented for every type. It aims to pro= vide the same type +/// inference help as `HasPinData`. +/// +/// # Safety +/// +/// Only the `init` module is allowed to use this trait. +pub unsafe trait HasInitData { + type InitData: InitData; + + unsafe fn __init_data() -> Self::InitData; +} + +/// Same function as `PinData`, but for arbitrary data. +/// +/// # Safety +/// +/// Only the `init` module is allowed to use this trait. +pub unsafe trait InitData: Copy { + type Datee: ?Sized + HasInitData; + + /// Type inference helper function. + fn make_closure(self, f: F) -> F + where + F: FnOnce(*mut Self::Datee) -> Result, + { + f + } +} + +pub struct AllData(PhantomData) -> Box>); + +impl Clone for AllData { + fn clone(&self) -> Self { + *self + } +} + +impl Copy for AllData {} + +unsafe impl InitData for AllData { + type Datee =3D T; +} + +unsafe impl HasInitData for T { + type InitData =3D AllData; + + unsafe fn __init_data() -> Self::InitData { + AllData(PhantomData) + } +} + +/// When a value of this type is dropped, it drops a `T`. +/// +/// Can be forgotton to prevent the drop. +pub struct DropGuard { + ptr: *mut T, + do_drop: Cell, +} + +impl DropGuard { + /// Creates a new [`DropGuard`]. It will [`ptr::drop_in_place`] `pt= r` when it gets dropped. + /// + /// # Safety + /// + /// `ptr` must be a valid pointer. + /// + /// It is the callers responsibility that `self` will only get dropped= if the pointee of `ptr`: + /// - has not been dropped, + /// - is not accessible by any other means, + /// - will not be dropped by any other means. + #[inline] + pub unsafe fn new(ptr: *mut T) -> Self { + Self { + ptr, + do_drop: Cell::new(true), + } + } + + /// Prevents this guard from dropping the supplied pointer. + /// + /// # Safety + /// + /// This function is unsafe in order to prevent safe code from forgett= ing this guard. It should + /// only be called by the macros in this module. + #[inline] + pub unsafe fn forget(&self) { + self.do_drop.set(false); + } +} + +impl Drop for DropGuard { + #[inline] + fn drop(&mut self) { + if self.do_drop.get() { + // SAFETY: A `DropGuard` can only be constructed using the uns= afe `new` function + // ensuring that this operation is safe. + unsafe { ptr::drop_in_place(self.ptr) } + } + } +} diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs new file mode 100644 index 000000000000..e27c309c7ffd --- /dev/null +++ b/rust/kernel/init/macros.rs @@ -0,0 +1,707 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +//! This module provides the macros that actually implement the proc-macro= s `pin_data` and +//! `pinned_drop`. +//! +//! These macros should never be called directly, since they expect their = input to be +//! in a certain format which is internal. Use the proc-macros instead. +//! +//! This architecture has been chosen because the kernel does not yet have= access to `syn` which +//! would make matters a lot easier for implementing these as proc-macros. +//! +//! # Macro expansion example +//! +//! This section is intended for readers trying to understand the macros i= n this module and the +//! `pin_init!` macros from `init.rs`. +//! +//! We will look at the following example: +//! +//! ```rust +//! # use kernel::init::*; +//! #[pin_data] +//! #[repr(C)] +//! struct Bar { +//! #[pin] +//! t: T, +//! pub x: usize, +//! } +//! +//! impl Bar { +//! fn new(t: T) -> impl PinInit { +//! pin_init!(Self { t, x: 0 }) +//! } +//! } +//! ``` +//! +//! This example includes the most common and important features of the pi= n-init API. +//! +//! Below you can find individual section about the different macro invoca= tions. Here are some +//! general things we need to take into account when designing macros: +//! - use global paths, similarly to file paths, these start with the sepa= rator: `::core::panic!()` +//! this ensures that the correct item is used, since users could define= their own `mod core {}` +//! and then their own `panic!` inside to execute arbitrary code inside = of our macro. +//! - macro `unsafe` hygene: we need to ensure that we do not expand arbit= rary, user-supplied +//! expressions inside of an `unsafe` block in the macro, because this w= ould allow users to do +//! `unsafe` operations without an associated `unsafe` block. +//! +//! ## `#[pin_data]` on `Bar` +//! +//! This macro is used to specify which fields are structurally pinned and= which fields are not. It +//! is placed on the struct definition and allows `#[pin]` to be placed on= the fields. +//! +//! Here is the definition of `Bar` from our example: +//! +//! ```rust +//! # use kernel::init::*; +//! #[pin_data] +//! #[repr(C)] +//! struct Bar { +//! t: T, +//! pub x: usize, +//! } +//! ``` +//! +//! This expands to the following code: +//! +//! ```rust +//! // Firstly the normal definition of the struct, attributes are preserv= ed: +//! #[repr(C)] +//! struct Bar { +//! t: T, +//! pub x: usize, +//! } +//! // Then an anonymous constant is defined, this is because we do not wa= nt any code to access the +//! // types that we define inside: +//! const _: () =3D { +//! // We define the pin-data carrying struct, it is a ZST and needs t= o have the same generics, +//! // since we need to implement access functions for each field and = thus need to know its +//! // type. +//! struct __ThePinData { +//! __phantom: ::core::marker::PhantomData) -> Bar>, +//! } +//! // We implement `Copy` for the pin-data struct, since all function= s it defines will take +//! // `self` by value. +//! impl ::core::clone::Clone for __ThePinData { +//! fn clone(&self) -> Self { +//! *self +//! } +//! } +//! impl ::core::marker::Copy for __ThePinData {} +//! // For every field of `Bar`, the pin-data struct will define a fun= ction with the same name +//! // and accessor (`pub` or `pub(crate)` etc.). This function will t= ake a pointer to the +//! // field (`slot`) and a `PinInit` or `Init` depending on the proje= ction kind of the field +//! // (if pinning is structural for the field, then `PinInit` otherwi= se `Init`). +//! #[allow(dead_code)] +//! impl __ThePinData { +//! unsafe fn t( +//! self, +//! slot: *mut T, +//! init: impl ::kernel::init::Init, +//! ) -> ::core::result::Result<(), E> { +//! unsafe { ::kernel::init::Init::__init(init, slot) } +//! } +//! pub unsafe fn x( +//! self, +//! slot: *mut usize, +//! init: impl ::kernel::init::Init, +//! ) -> ::core::result::Result<(), E> { +//! unsafe { ::kernel::init::Init::__init(init, slot) } +//! } +//! } +//! // Implement the internal `HasPinData` trait that associates `Bar`= with the pin-data struct +//! // that we constructed beforehand. +//! unsafe impl ::kernel::init::__internal::HasPinData for Bar { +//! type PinData =3D __ThePinData; +//! unsafe fn __pin_data() -> Self::PinData { +//! __ThePinData { +//! __phantom: ::core::marker::PhantomData, +//! } +//! } +//! } +//! // Implement the internal `PinData` trait that marks the pin-data = struct as a pin-data +//! // struct. This is important to ensure that no user can implement = a rouge `__pin_data` +//! // function without using `unsafe`. +//! unsafe impl ::kernel::init::__internal::PinData for __ThePinDat= a { +//! type Datee =3D Bar; +//! } +//! // Now we only want to implement `Unpin` for `Bar` when every stru= cturally pinned field is +//! // `Unpin`. In other words, whether `Bar` is `Unpin` only depends = on structurally pinned +//! // fields (those marked with `#[pin]`). These fields will be liste= d in this struct, in our +//! // case no such fields exist, hence this is almost empty. The two = phantomdata fields exist +//! // for two reasons: +//! // - `__phantom`: every generic must be used, since we cannot real= ly know which generics +//! // are used, we declere all and then use everything here once. +//! // - `__phantom_pin`: uses the `'__pin` lifetime and ensures that = this struct is invariant +//! // over it. The lifetime is needed to work around the limitation= that trait bounds must +//! // not be trivial, e.g. the user has a `#[pin] PhantomPinned` fi= eld -- this is +//! // unconditionally `!Unpin` and results in an error. The lifetim= e tricks the compiler +//! // into accepting these bounds regardless. +//! #[allow(dead_code)] +//! struct __Unpin<'__pin, T> { +//! __phantom_pin: ::core::marker::PhantomData &= '__pin ()>, +//! __phantom: ::core::marker::PhantomData) -> Bar>, +//! } +//! #[doc(hidden)] +//! impl<'__pin, T> +//! ::core::marker::Unpin for Bar where __Unpin<'__pin, T>: ::c= ore::marker::Unpin {} +//! // Now we need to ensure that `Bar` does not implement `Drop`, sin= ce that would give users +//! // access to `&mut self` inside of `drop` even if the struct was p= inned. This could lead to +//! // UB with only safe code, so we disallow this by giving a trait i= mplementation error using +//! // a direct impl and a blanket implementation. +//! trait MustNotImplDrop {} +//! // Normally `Drop` bounds do not have the correct semantics, but f= or this purpose they do +//! // (normally people want to know if a type has any kind of drop gl= ue at all, here we want +//! // to know if it has any kind of custom drop glue, which is exactl= y what this bound does). +//! #[allow(drop_bounds)] +//! impl MustNotImplDrop for T {} +//! impl MustNotImplDrop for Bar {} +//! }; +//! ``` +//! +//! ## `pin_init!` in `impl Bar` +//! +//! This macro creates an pin-initializer for the given struct. It require= s that the struct is +//! annotated by `#[pin_data]`. +//! +//! Here is the impl on `Bar` defining the new function: +//! +//! ```rust +//! impl Bar { +//! fn new(t: T) -> impl PinInit { +//! pin_init!(Self { t, x: 0 }) +//! } +//! } +//! ``` +//! +//! This expands to the following code: +//! +//! ```rust +//! impl Bar { +//! fn new(t: T) -> impl PinInit { +//! { +//! // We do not want to allow arbitrary returns, so we declar= e this type as the `Ok` +//! // return type and shadow it later when we insert the arbi= trary user code. That way +//! // there will be no possibility of returning without `unsa= fe`. +//! struct __InitOk; +//! // Get the pin-data type from the initialized type. +//! // - the function is unsafe, hence the unsafe block +//! // - we `use` the `HasPinData` trait in the block, it is o= nly available in that +//! // scope. +//! let data =3D unsafe { +//! use ::kernel::init::__internal::HasPinData; +//! Self::__pin_data() +//! }; +//! // Use `data` to help with type inference, the closure sup= plied will have the type +//! // `FnOnce(*mut Self) -> Result<__InitOk, Infallible>`. +//! let init =3D ::kernel::init::__internal::PinData::make_clo= sure::< +//! _, +//! __InitOk, +//! ::core::convert::Infallible, +//! >(data, move |slot| { +//! { +//! // Shadow the structure so it cannot be used to re= turn early. If a user +//! // tries to write `return Ok(__InitOk)`, then they= get a type error, since +//! // that will refer to this struct instead of the o= ne defined above. +//! struct __InitOk; +//! // This is the expansion of `t,`, which is syntact= ic sugar for `t: t,`. +//! unsafe { ::core::ptr::write(&raw mut (*slot).t, t)= }; +//! // Since initialization could fail later (not in t= his case, since the error +//! // type is `Infallible`) we will need to drop this= field if it fails. This +//! // `DropGuard` will drop the field when it gets dr= opped and has not yet +//! // been forgotten. We make a reference to it, so u= sers cannot `mem::forget` +//! // it from the initializer, since the name is the = same as the field. +//! let t =3D &unsafe { +//! ::kernel::init::__internal::DropGuard::new(&ra= w mut (*slot).t) +//! }; +//! // Expansion of `x: 0,`: +//! // Since this can be an arbitrary expression we ca= nnot place it inside of +//! // the `unsafe` block, so we bind it here. +//! let x =3D 0; +//! unsafe { ::core::ptr::write(&raw mut (*slot).x, x)= }; +//! let x =3D &unsafe { +//! ::kernel::init::__internal::DropGuard::new(&ra= w mut (*slot).x) +//! }; +//! +//! // Here we use the type checker to ensuer that eve= ry field has been +//! // initialized exactly once, since this is `if fal= se` it will never get +//! // executed, but still type-checked. +//! // Additionally we abuse `slot` to automatically i= nfer the correct type for +//! // the struct. This is also another check that eve= ry field is accessible +//! // from this scope. +//! #[allow(unreachable_code, clippy::diverging_sub_ex= pression)] +//! if false { +//! unsafe { +//! ::core::ptr::write( +//! slot, +//! Self { +//! // We only care about typecheck fi= nding every field here, +//! // the expression does not matter,= just conjure one using +//! // `panic!()`: +//! t: ::core::panic!(), +//! x: ::core::panic!(), +//! }, +//! ); +//! }; +//! } +//! // Since initialization has successfully completed= , we can now forget the +//! // guards. +//! unsafe { ::kernel::init::__internal::DropGuard::fo= rget(t) }; +//! unsafe { ::kernel::init::__internal::DropGuard::fo= rget(x) }; +//! } +//! // We leave the scope above and gain access to the pre= viously shadowed +//! // `__InitOk` that we need to return. +//! Ok(__InitOk) +//! }); +//! // Change the return type of the closure. +//! let init =3D move |slot| -> ::core::result::Result<(), ::c= ore::convert::Infallible> { +//! init(slot).map(|__InitOk| ()) +//! }; +//! // Construct the initializer. +//! let init =3D unsafe { +//! ::kernel::init::pin_init_from_closure::<_, ::core::con= vert::Infallible>(init) +//! }; +//! init +//! } +//! } +//! } +//! ``` + +/// This macro first parses the struct definition such that it separates p= inned and not pinned +/// fields. Afterwards it declares the struct and implement the `PinData` = trait safely. +#[doc(hidden)] +#[macro_export] +macro_rules! __pin_data { + // Proc-macro entry point, this is supplied by the proc-macro pre-pars= ing. + (parse_input: + @args($($pinned_drop:ident)?), + @sig( + $(#[$($struct_attr:tt)*])* + $vis:vis struct $name:ident + $(where $($whr:tt)*)? + ), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @body({ $($fields:tt)* }), + ) =3D> { + // We now use token munching to iterate through all of the fields.= While doing this we + // identify fields marked with `#[pin]`, these fields are the 'pin= ned fields'. The user + // wants these to be structurally pinned. The rest of the fields a= re the + // 'not pinned fields'. Additionally we collect all fields, since = we need them in the right + // order to declare the struct. + // + // In this call we also put some explaining comments for the param= eters. + $crate::__pin_data!(find_pinned_fields: + // Attributes on the struct itself, these will just be propaga= ted to be put onto the + // struct definition. + @struct_attrs($(#[$($struct_attr)*])*), + // The visibility of the struct. + @vis($vis), + // The name of the struct. + @name($name), + // The 'impl generics', the generics that will need to be spec= ified on the struct inside + // of an `impl<$ty_generics>` block. + @impl_generics($($impl_generics)*), + // The 'ty generics', the generics that will need to be specif= ied on the impl blocks. + @ty_generics($($ty_generics)*), + // The where clause of any impl block and the declaration. + @where($($($whr)*)?), + // The remaining fields tokens that need to be processed. + // We add a `,` at the end to ensure correct parsing. + @fields_munch($($fields)* ,), + // The pinned fields. + @pinned(), + // The not pinned fields. + @not_pinned(), + // All fields. + @fields(), + // The accumulator containing all attributes already parsed. + @accum(), + // Contains `yes` or `` to indicate if `#[pin]` was found on t= he current field. + @is_pinned(), + // The proc-macro argument, this should be `PinnedDrop` or ``. + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // We found a PhantomPinned field, this should generally be pinned! + @fields_munch($field:ident : $($($(::)?core::)?marker::)?PhantomPi= nned, $($rest:tt)*), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum($($accum:tt)*), + // This field is not pinned. + @is_pinned(), + @pinned_drop($($pinned_drop:ident)?), + ) =3D> { + ::core::compile_error!(concat!( + "The field `", + stringify!($field), + "` of type `PhantomPinned` only has an effect, if it has the `= #[pin]` attribute.", + )); + $crate::__pin_data!(find_pinned_fields: + @struct_attrs($($struct_attrs)*), + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @fields_munch($($rest)*), + @pinned($($pinned)* $($accum)* $field: ::core::marker::Phantom= Pinned,), + @not_pinned($($not_pinned)*), + @fields($($fields)* $($accum)* $field: ::core::marker::Phantom= Pinned,), + @accum(), + @is_pinned(), + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // We reached the field declaration. + @fields_munch($field:ident : $type:ty, $($rest:tt)*), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum($($accum:tt)*), + // This field is pinned. + @is_pinned(yes), + @pinned_drop($($pinned_drop:ident)?), + ) =3D> { + $crate::__pin_data!(find_pinned_fields: + @struct_attrs($($struct_attrs)*), + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @fields_munch($($rest)*), + @pinned($($pinned)* $($accum)* $field: $type,), + @not_pinned($($not_pinned)*), + @fields($($fields)* $($accum)* $field: $type,), + @accum(), + @is_pinned(), + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // We reached the field declaration. + @fields_munch($field:ident : $type:ty, $($rest:tt)*), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum($($accum:tt)*), + // This field is not pinned. + @is_pinned(), + @pinned_drop($($pinned_drop:ident)?), + ) =3D> { + $crate::__pin_data!(find_pinned_fields: + @struct_attrs($($struct_attrs)*), + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @fields_munch($($rest)*), + @pinned($($pinned)*), + @not_pinned($($not_pinned)* $($accum)* $field: $type,), + @fields($($fields)* $($accum)* $field: $type,), + @accum(), + @is_pinned(), + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // We found the `#[pin]` attr. + @fields_munch(#[pin] $($rest:tt)*), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum($($accum:tt)*), + @is_pinned($($is_pinned:ident)?), + @pinned_drop($($pinned_drop:ident)?), + ) =3D> { + $crate::__pin_data!(find_pinned_fields: + @struct_attrs($($struct_attrs)*), + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @fields_munch($($rest)*), + // We do not include `#[pin]` in the list of attributes, since= it is not actually an + // attribute that is defined somewhere. + @pinned($($pinned)*), + @not_pinned($($not_pinned)*), + @fields($($fields)*), + @accum($($accum)*), + // Set this to `yes`. + @is_pinned(yes), + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // We reached the field declaration with visibility, for simplicit= y we only munch the + // visibility and put it into `$accum`. + @fields_munch($fvis:vis $field:ident $($rest:tt)*), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum($($accum:tt)*), + @is_pinned($($is_pinned:ident)?), + @pinned_drop($($pinned_drop:ident)?), + ) =3D> { + $crate::__pin_data!(find_pinned_fields: + @struct_attrs($($struct_attrs)*), + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @fields_munch($field $($rest)*), + @pinned($($pinned)*), + @not_pinned($($not_pinned)*), + @fields($($fields)*), + @accum($($accum)* $fvis), + @is_pinned($($is_pinned)?), + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // Some other attribute, just put it into `$accum`. + @fields_munch(#[$($attr:tt)*] $($rest:tt)*), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum($($accum:tt)*), + @is_pinned($($is_pinned:ident)?), + @pinned_drop($($pinned_drop:ident)?), + ) =3D> { + $crate::__pin_data!(find_pinned_fields: + @struct_attrs($($struct_attrs)*), + @vis($vis), + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @fields_munch($($rest)*), + @pinned($($pinned)*), + @not_pinned($($not_pinned)*), + @fields($($fields)*), + @accum($($accum)* #[$($attr)*]), + @is_pinned($($is_pinned)?), + @pinned_drop($($pinned_drop)?), + ); + }; + (find_pinned_fields: + @struct_attrs($($struct_attrs:tt)*), + @vis($vis:vis), + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + // We reached the end of the fields, plus an optional additional c= omma, since we added one + // before and the user is also allowed to put a trailing comma. + @fields_munch($(,)?), + @pinned($($pinned:tt)*), + @not_pinned($($not_pinned:tt)*), + @fields($($fields:tt)*), + @accum(), + @is_pinned(), + @pinned_drop($($pinned_drop:ident)?), + ) =3D> { + // Declare the struct with all fields in the correct order. + $($struct_attrs)* + $vis struct $name <$($impl_generics)*> + where $($whr)* + { + $($fields)* + } + + // We put the rest into this const item, because it then will not = be accessible to anything + // outside. + const _: () =3D { + // We declare this struct which will host all of the projectio= n function for our type. + // it will be invariant over all generic parameters which are = inherited from the + // struct. + $vis struct __ThePinData<$($impl_generics)*> + where $($whr)* + { + __phantom: ::core::marker::PhantomData< + fn($name<$($ty_generics)*>) -> $name<$($ty_generics)*> + >, + } + + impl<$($impl_generics)*> ::core::clone::Clone for __ThePinData= <$($ty_generics)*> + where $($whr)* + { + fn clone(&self) -> Self { *self } + } + + impl<$($impl_generics)*> ::core::marker::Copy for __ThePinData= <$($ty_generics)*> + where $($whr)* + {} + + // Make all projection functions. + $crate::__pin_data!(make_pin_data: + @pin_data(__ThePinData), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @pinned($($pinned)*), + @not_pinned($($not_pinned)*), + ); + + // SAFETY: We have added the correct projection functions abov= e to `__ThePinData` and + // we also use the least restrictive generics possible. + unsafe impl<$($impl_generics)*> + $crate::init::__internal::HasPinData for $name<$($ty_gener= ics)*> + where $($whr)* + { + type PinData =3D __ThePinData<$($ty_generics)*>; + + unsafe fn __pin_data() -> Self::PinData { + __ThePinData { __phantom: ::core::marker::PhantomData } + } + } + + unsafe impl<$($impl_generics)*> + $crate::init::__internal::PinData for __ThePinData<$($ty_g= enerics)*> + where $($whr)* + { + type Datee =3D $name<$($ty_generics)*>; + } + + // This struct will be used for the unpin analysis. Since only= structurally pinned + // fields are relevant whether the struct should implement `Un= pin`. + #[allow(dead_code)] + struct __Unpin <'__pin, $($impl_generics)*> + where $($whr)* + { + __phantom_pin: ::core::marker::PhantomData &'__pin ()>, + __phantom: ::core::marker::PhantomData< + fn($name<$($ty_generics)*>) -> $name<$($ty_generics)*> + >, + // Only the pinned fields. + $($pinned)* + } + + #[doc(hidden)] + impl<'__pin, $($impl_generics)*> ::core::marker::Unpin for $na= me<$($ty_generics)*> + where + __Unpin<'__pin, $($ty_generics)*>: ::core::marker::Unpin, + $($whr)* + {} + + // We need to disallow normal `Drop` implementation, the exact= behavior depends on + // whether `PinnedDrop` was specified as the parameter. + $crate::__pin_data!(drop_prevention: + @name($name), + @impl_generics($($impl_generics)*), + @ty_generics($($ty_generics)*), + @where($($whr)*), + @pinned_drop($($pinned_drop)?), + ); + }; + }; + // When no `PinnedDrop` was specified, then we have to prevent impleme= nting drop. + (drop_prevention: + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + @pinned_drop(), + ) =3D> { + // We prevent this by creating a trait that will be implemented fo= r all types implementing + // `Drop`. Additionally we will implement this trait for the struc= t leading to a conflict, + // if it also implements `Drop` + trait MustNotImplDrop {} + #[allow(drop_bounds)] + impl MustNotImplDrop for T {} + impl<$($impl_generics)*> MustNotImplDrop for $name<$($ty_generics)= *> + where $($whr)* {} + }; + // If some other parameter was specified, we emit a readable error. + (drop_prevention: + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + @pinned_drop($($rest:tt)*), + ) =3D> { + compile_error!( + "Wrong parameters to `#[pin_data]`, expected nothing or `Pinne= dDrop`, got '{}'.", + stringify!($($rest)*), + ); + }; + (make_pin_data: + @pin_data($pin_data:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + @pinned($($(#[$($p_attr:tt)*])* $pvis:vis $p_field:ident : $p_type= :ty),* $(,)?), + @not_pinned($($(#[$($attr:tt)*])* $fvis:vis $field:ident : $type:t= y),* $(,)?), + ) =3D> { + // For every field, we create a projection function according to i= ts projection type. If a + // field is structurally pinned, then it must be initialized via `= PinInit`, if it is not + // structurally pinned, then it can be initialized via `Init`. + // + // The functions are `unsafe` to prevent accidentally calling them. + #[allow(dead_code)] + impl<$($impl_generics)*> $pin_data<$($ty_generics)*> + where $($whr)* + { + $( + $pvis unsafe fn $p_field( + self, + slot: *mut $p_type, + init: impl $crate::init::PinInit<$p_type, E>, + ) -> ::core::result::Result<(), E> { + unsafe { $crate::init::PinInit::__pinned_init(init, sl= ot) } + } + )* + $( + $fvis unsafe fn $field( + self, + slot: *mut $type, + init: impl $crate::init::Init<$type, E>, + ) -> ::core::result::Result<(), E> { + unsafe { $crate::init::Init::__init(init, slot) } + } + )* + } + }; +} diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index 82b520f024dd..4def038fe71a 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -7,6 +7,7 @@ mod quote; mod concat_idents; mod helpers; mod module; +mod pin_data; mod vtable; use proc_macro::TokenStream; @@ -168,3 +169,31 @@ pub fn vtable(attr: TokenStream, ts: TokenStream) -> T= okenStream { pub fn concat_idents(ts: TokenStream) -> TokenStream { concat_idents::concat_idents(ts) } + +/// Used to specify the pinning information of the fields of a struct. +/// +/// This is somewhat similar in purpose as +/// [pin-project-lite](https://crates.io/crates/pin-project-lite). +/// Place this macro on a struct definition and then `#[pin]` in front of = the attributes of each +/// field you want to structurally pin. +/// +/// This macro enables the use of the [`pin_init!`] macro. When pin-initia= lizing a `struct`, +/// then `#[pin]` directs the type of intializer that is required. +/// +/// # Examples +/// +/// ```rust,ignore +/// #[pin_data] +/// struct DriverData { +/// #[pin] +/// queue: Mutex>, +/// buf: Box<[u8; 1024 * 1024]>, +/// } +/// ``` +/// +/// [`pin_init!`]: ../kernel/macro.pin_init.html +// ^ cannot use direct link, since `kernel` is not a dependency of `macro= s`. +#[proc_macro_attribute] +pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream { + pin_data::pin_data(inner, item) +} diff --git a/rust/macros/pin_data.rs b/rust/macros/pin_data.rs new file mode 100644 index 000000000000..954149d77181 --- /dev/null +++ b/rust/macros/pin_data.rs @@ -0,0 +1,79 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +use proc_macro::{Punct, Spacing, TokenStream, TokenTree}; + +pub(crate) fn pin_data(args: TokenStream, input: TokenStream) -> TokenStre= am { + // This proc-macro only does some pre-parsing and then delegates the a= ctual parsing to + // `kernel::__pin_data!`. + // + // In here we only collect the generics, since parsing them in declara= tive macros is very + // elaborate. We also do not need to analyse their structure, we only = need to collect them. + + // `impl_generics`, the declared generics with their bounds. + let mut impl_generics =3D vec![]; + // Only the names of the generics, without any bounds. + let mut ty_generics =3D vec![]; + // Tokens not related to the generics e.g. the `impl` token. + let mut rest =3D vec![]; + // The current level of `<`. + let mut nesting =3D 0; + let mut toks =3D input.into_iter(); + // If we are at the beginning of a generic parameter. + let mut at_start =3D true; + for tt in &mut toks { + match tt.clone() { + TokenTree::Punct(p) if p.as_char() =3D=3D '<' =3D> { + if nesting >=3D 1 { + impl_generics.push(tt); + } + nesting +=3D 1; + } + TokenTree::Punct(p) if p.as_char() =3D=3D '>' =3D> { + if nesting =3D=3D 0 { + break; + } else { + nesting -=3D 1; + if nesting >=3D 1 { + impl_generics.push(tt); + } + if nesting =3D=3D 0 { + break; + } + } + } + tt =3D> { + if nesting =3D=3D 1 { + match &tt { + TokenTree::Ident(i) if i.to_string() =3D=3D "const= " =3D> {} + TokenTree::Ident(_) if at_start =3D> { + ty_generics.push(tt.clone()); + ty_generics.push(TokenTree::Punct(Punct::new('= ,', Spacing::Alone))); + at_start =3D false; + } + TokenTree::Punct(p) if p.as_char() =3D=3D ',' =3D>= at_start =3D true, + TokenTree::Punct(p) if p.as_char() =3D=3D '\'' && = at_start =3D> { + ty_generics.push(tt.clone()); + } + _ =3D> {} + } + } + if nesting >=3D 1 { + impl_generics.push(tt); + } else if nesting =3D=3D 0 { + rest.push(tt); + } + } + } + } + rest.extend(toks); + // This should be the body of the struct `{...}`. + let last =3D rest.pop(); + quote!(::kernel::__pin_data! { + parse_input: + @args(#args), + @sig(#(#rest)*), + @impl_generics(#(#impl_generics)*), + @ty_generics(#(#ty_generics)*), + @body(#last), + }) +} diff --git a/rust/macros/quote.rs b/rust/macros/quote.rs index 94a6277182ee..c8e08b3c1e4c 100644 --- a/rust/macros/quote.rs +++ b/rust/macros/quote.rs @@ -38,7 +38,6 @@ impl ToTokens for TokenStream { /// This is a similar to the /// [`quote_spanned!`](https://docs.rs/quote/latest/quote/macro.quote_span= ned.html) macro from the /// `quote` crate but provides only just enough functionality needed by th= e current `macros` crate. -#[allow(unused_macros)] macro_rules! quote_spanned { ($span:expr =3D> $($tt:tt)*) =3D> { #[allow(clippy::vec_init_then_push)] @@ -137,7 +136,6 @@ macro_rules! quote_spanned { /// `macros` crate. /// /// [`Span::mixed_site()`]: https://doc.rust-lang.org/proc_macro/struct.Sp= an.html#method.mixed_site -#[allow(unused_macros)] macro_rules! quote { ($($tt:tt)*) =3D> { quote_spanned!(::proc_macro::Span::mixed_site() =3D> $($tt)*) -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 5C259C77B6C for ; Sat, 8 Apr 2023 12:27:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230425AbjDHM1F (ORCPT ); Sat, 8 Apr 2023 08:27:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229898AbjDHM1B (ORCPT ); Sat, 8 Apr 2023 08:27:01 -0400 Received: from mail-40131.protonmail.ch (mail-40131.protonmail.ch [185.70.40.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A8C9EF92 for ; Sat, 8 Apr 2023 05:26:33 -0700 (PDT) Date: Sat, 08 Apr 2023 12:25:56 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956768; x=1681215968; bh=OXsy9FUf2/pTxzJkmYttEYBmHi/XjrZ4xyoTpAIdtLY=; 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=glEeAk6iqpzyq2UoWI6kNdaY6XyI00BxLikpkhTA3bdxQ8RIDxs6wB2POrSiAzynl t1lCS+bElTm0iOls3mTPod392aUgf/UY+aP+NIlPGkL0Q7huFxHUXikovPBuOqxEj0 CZz57T+gow84zN8iKVtTtAVKuY+E69wIWIPS7fa0Mp1OAukW7/rqw3WMsOHx8FcQ5h w7hryrSvdQdZJYkt5MpboPxq3OceGfo6g2LJrHq7Ans4q1TjECck4cbzczX/jG8CtG 1xSnPBDIovEfwpWwx0Oe8S2+LrCgAjEvIjAbjq2OA53UbH6hTvzS9Wc+zvaqnOJTC5 zzkeJ2wB9xXCA== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Alice Ryhl , Andreas Hindborg Subject: [PATCH v7 08/15] rust: init/sync: add `InPlaceInit` trait to pin-initialize smart pointers Message-ID: <20230408122429.1103522-9-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 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::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 From nobody Sun Feb 8 01:31:22 2026 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 97C4BC77B61 for ; Sat, 8 Apr 2023 12:27:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231311AbjDHM1L (ORCPT ); Sat, 8 Apr 2023 08:27:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35020 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231126AbjDHM1B (ORCPT ); Sat, 8 Apr 2023 08:27:01 -0400 Received: from mail-4316.protonmail.ch (mail-4316.protonmail.ch [185.70.43.16]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62422EFA1; Sat, 8 Apr 2023 05:26:35 -0700 (PDT) Date: Sat, 08 Apr 2023 12:26:01 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956768; x=1681215968; bh=FJbhO3VEiHokQvGY2M/ymGbQQklx1Tj5FLDg3VFtS04=; 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=f6NWYYnDjdOxGva93lALYdq3b4NudmPyas4+kshL7UR8Q2OQiKMWiq01uk92o+8Hl RcKbkd3I6ZOshq9QW89i3TuSM9gA7DM0+lcBbhgtVUinEIVkLckEy9Ascg8Lh8RPew JRoqowj7jPLYWIgVbGpBbAg5rikaZm9QCAB22i9ZjloBXaUCDt11XUT5PxW6xWUB1O u7pS4gweEHsw2/ffhb7uNnAmKhXyGOQxrCKWxuvUP/82e84knagaQsVO/NEKFzmytr NZZv3GA/2GHjEAwqo4bn4z+k5DE8uPFLOtHQetWLkVMBffb2cfgcjP88BCaMAj18u3 4XwWvdijsybSw== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Alice Ryhl , Andreas Hindborg Subject: [PATCH v7 09/15] rust: init: add `PinnedDrop` trait and macros Message-ID: <20230408122429.1103522-10-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The `PinnedDrop` trait that facilitates destruction of pinned types. It has to be implemented via the `#[pinned_drop]` macro, since the `drop` function should not be called by normal code, only by other destructors. It also only works on structs that are annotated with `#[pin_data(PinnedDrop)]`. Co-developed-by: Gary Guo Signed-off-by: Gary Guo Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg --- rust/kernel/init.rs | 111 ++++++++++++++ rust/kernel/init/__internal.rs | 15 ++ rust/kernel/init/macros.rs | 264 +++++++++++++++++++++++++++++++++ rust/macros/lib.rs | 49 ++++++ rust/macros/pinned_drop.rs | 49 ++++++ 5 files changed, 488 insertions(+) create mode 100644 rust/macros/pinned_drop.rs diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index 6499cf5c9c20..37e8159df24d 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -104,6 +104,78 @@ //! } //! ``` //! +//! ## Manual creation of an initializer +//! +//! Often when working with primitives the previous approaches are not suf= ficient. That is where +//! [`pin_init_from_closure()`] comes in. This `unsafe` function allows yo= u to create a +//! [`impl PinInit`] directly from a closure. Of course you have to = ensure that the closure +//! actually does the initialization in the correct way. Here are the thin= gs to look out for +//! (we are calling the parameter to the closure `slot`): +//! - when the closure returns `Ok(())`, then it has completed the initial= ization successfully, so +//! `slot` now contains a valid bit pattern for the type `T`, +//! - when the closure returns `Err(e)`, then the caller may deallocate th= e memory at `slot`, so +//! you need to take care to clean up anything if your initialization fa= ils mid-way, +//! - you may assume that `slot` will stay pinned even after the closure r= eturns until `drop` of +//! `slot` gets called. +//! +//! ```rust +//! use kernel::{prelude::*, init}; +//! use core::{ptr::addr_of_mut, marker::PhantomPinned, pin::Pin}; +//! # mod bindings { +//! # pub struct foo; +//! # pub unsafe fn init_foo(_ptr: *mut foo) {} +//! # pub unsafe fn destroy_foo(_ptr: *mut foo) {} +//! # pub unsafe fn enable_foo(_ptr: *mut foo, _flags: u32) -> i32 { 0= } +//! # } +//! /// # Invariants +//! /// +//! /// `foo` is always initialized +//! #[pin_data(PinnedDrop)] +//! pub struct RawFoo { +//! #[pin] +//! foo: Opaque, +//! #[pin] +//! _p: PhantomPinned, +//! } +//! +//! impl RawFoo { +//! pub fn new(flags: u32) -> impl PinInit { +//! // SAFETY: +//! // - when the closure returns `Ok(())`, then it has successful= ly initialized and +//! // enabled `foo`, +//! // - when it returns `Err(e)`, then it has cleaned up before +//! unsafe { +//! init::pin_init_from_closure(move |slot: *mut Self| { +//! // `slot` contains uninit memory, avoid creating a ref= erence. +//! let foo =3D addr_of_mut!((*slot).foo); +//! +//! // Initialize the `foo` +//! bindings::init_foo(Opaque::raw_get(foo)); +//! +//! // Try to enable it. +//! let err =3D bindings::enable_foo(Opaque::raw_get(foo),= flags); +//! if err !=3D 0 { +//! // Enabling has failed, first clean up the foo and= then return the error. +//! bindings::destroy_foo(Opaque::raw_get(foo)); +//! return Err(Error::from_kernel_errno(err)); +//! } +//! +//! // All fields of `RawFoo` have been initialized, since= `_p` is a ZST. +//! Ok(()) +//! }) +//! } +//! } +//! } +//! +//! #[pinned_drop] +//! impl PinnedDrop for RawFoo { +//! fn drop(self: Pin<&mut Self>) { +//! // SAFETY: Since `foo` is initialized, destroying is safe. +//! unsafe { bindings::destroy_foo(self.foo.get()) }; +//! } +//! } +//! ``` +//! //! [`sync`]: kernel::sync //! [pinning]: https://doc.rust-lang.org/std/pin/index.html //! [structurally pinned fields]: @@ -1084,3 +1156,42 @@ impl InPlaceInit for UniqueArc { Ok(unsafe { this.assume_init() }) } } + +/// Trait facilitating pinned destruction. +/// +/// Use [`pinned_drop`] to implement this trait safely: +/// +/// ```rust +/// # use kernel::sync::Mutex; +/// use kernel::macros::pinned_drop; +/// use core::pin::Pin; +/// #[pin_data(PinnedDrop)] +/// struct Foo { +/// #[pin] +/// mtx: Mutex, +/// } +/// +/// #[pinned_drop] +/// impl PinnedDrop for Foo { +/// fn drop(self: Pin<&mut Self>) { +/// pr_info!("Foo is being dropped!"); +/// } +/// } +/// ``` +/// +/// # Safety +/// +/// This trait must be implemented via the [`pinned_drop`] proc-macro attr= ibute on the impl. +/// +/// [`pinned_drop`]: kernel::macros::pinned_drop +pub unsafe trait PinnedDrop: __internal::HasPinData { + /// Executes the pinned destructor of this type. + /// + /// While this function is marked safe, it is actually unsafe to call = it manually. For this + /// reason it takes an additional parameter. This type can only be con= structed by `unsafe` code + /// and thus prevents this function from being called where it should = not. + /// + /// This extra parameter will be generated by the `#[pinned_drop]` pro= c-macro attribute + /// automatically. + fn drop(self: Pin<&mut Self>, only_call_from_drop: __internal::OnlyCal= lFromDrop); +} diff --git a/rust/kernel/init/__internal.rs b/rust/kernel/init/__internal.rs index 7aab9a8b0336..2445763ba97a 100644 --- a/rust/kernel/init/__internal.rs +++ b/rust/kernel/init/__internal.rs @@ -161,3 +161,18 @@ impl Drop for DropGuard { } } } + +/// Token used by `PinnedDrop` to prevent calling the function without cre= ating this unsafely +/// created struct. This is needed, because the `drop` function is safe, b= ut should not be called +/// manually. +pub struct OnlyCallFromDrop(()); + +impl OnlyCallFromDrop { + /// # Safety + /// + /// This function should only be called from the [`Drop::drop`] functi= on and only be used to + /// delegate the destruction to the pinned destructor [`PinnedDrop::dr= op`] of the same type. + pub unsafe fn new() -> Self { + Self(()) + } +} diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs index e27c309c7ffd..a1f555f305ff 100644 --- a/rust/kernel/init/macros.rs +++ b/rust/kernel/init/macros.rs @@ -31,6 +31,26 @@ //! pin_init!(Self { t, x: 0 }) //! } //! } +//! +//! #[pin_data(PinnedDrop)] +//! struct Foo { +//! a: usize, +//! #[pin] +//! b: Bar, +//! } +//! +//! #[pinned_drop] +//! impl PinnedDrop for Foo { +//! fn drop(self: Pin<&mut Self>) { +//! println!("{self:p} is getting dropped."); +//! } +//! } +//! +//! let a =3D 42; +//! let initializer =3D pin_init!(Foo { +//! a, +//! b <- Bar::new(36), +//! }); //! ``` //! //! This example includes the most common and important features of the pi= n-init API. @@ -155,6 +175,14 @@ //! #[allow(drop_bounds)] //! impl MustNotImplDrop for T {} //! impl MustNotImplDrop for Bar {} +//! // Here comes a convenience check, if one implemented `PinnedDrop`= , but forgot to add it to +//! // `#[pin_data]`, then this will error with the same mechanic as a= bove, this is not needed +//! // for safety, but a good sanity check, since no normal code calls= `PinnedDrop::drop`. +//! #[allow(non_camel_case_types)] +//! trait UselessPinnedDropImpl_you_need_to_specify_PinnedDrop {} +//! impl +//! UselessPinnedDropImpl_you_need_to_specify_PinnedDrop for T {} +//! impl UselessPinnedDropImpl_you_need_to_specify_PinnedDrop for B= ar {} //! }; //! ``` //! @@ -265,6 +293,210 @@ //! } //! } //! ``` +//! +//! ## `#[pin_data]` on `Foo` +//! +//! Since we already took a look at `#[pin_data]` on `Bar`, this section w= ill only explain the +//! differences/new things in the expansion of the `Foo` definition: +//! +//! ```rust +//! #[pin_data(PinnedDrop)] +//! struct Foo { +//! a: usize, +//! #[pin] +//! b: Bar, +//! } +//! ``` +//! +//! This expands to the following code: +//! +//! ```rust +//! struct Foo { +//! a: usize, +//! b: Bar, +//! } +//! const _: () =3D { +//! struct __ThePinData { +//! __phantom: ::core::marker::PhantomData Foo>, +//! } +//! impl ::core::clone::Clone for __ThePinData { +//! fn clone(&self) -> Self { +//! *self +//! } +//! } +//! impl ::core::marker::Copy for __ThePinData {} +//! #[allow(dead_code)] +//! impl __ThePinData { +//! unsafe fn b( +//! self, +//! slot: *mut Bar, +//! // Note that this is `PinInit` instead of `Init`, this is = because `b` is +//! // structurally pinned, as marked by the `#[pin]` attribut= e. +//! init: impl ::kernel::init::PinInit, E>, +//! ) -> ::core::result::Result<(), E> { +//! unsafe { ::kernel::init::PinInit::__pinned_init(init, slot= ) } +//! } +//! unsafe fn a( +//! self, +//! slot: *mut usize, +//! init: impl ::kernel::init::Init, +//! ) -> ::core::result::Result<(), E> { +//! unsafe { ::kernel::init::Init::__init(init, slot) } +//! } +//! } +//! unsafe impl ::kernel::init::__internal::HasPinData for Foo { +//! type PinData =3D __ThePinData; +//! unsafe fn __pin_data() -> Self::PinData { +//! __ThePinData { +//! __phantom: ::core::marker::PhantomData, +//! } +//! } +//! } +//! unsafe impl ::kernel::init::__internal::PinData for __ThePinData { +//! type Datee =3D Foo; +//! } +//! #[allow(dead_code)] +//! struct __Unpin<'__pin> { +//! __phantom_pin: ::core::marker::PhantomData &= '__pin ()>, +//! __phantom: ::core::marker::PhantomData Foo>, +//! // Since this field is `#[pin]`, it is listed here. +//! b: Bar, +//! } +//! #[doc(hidden)] +//! impl<'__pin> ::core::marker::Unpin for Foo where __Unpin<'__pin>: = ::core::marker::Unpin {} +//! // Since we specified `PinnedDrop` as the argument to `#[pin_data]= `, we expect `Foo` to +//! // implement `PinnedDrop`. Thus we do not need to prevent `Drop` i= mplementations like +//! // before, instead we implement it here and delegate to `PinnedDro= p`. +//! impl ::core::ops::Drop for Foo { +//! fn drop(&mut self) { +//! // Since we are getting dropped, no one else has a referen= ce to `self` and thus we +//! // can assume that we never move. +//! let pinned =3D unsafe { ::core::pin::Pin::new_unchecked(se= lf) }; +//! // Create the unsafe token that proves that we are inside = of a destructor, this +//! // type is only allowed to be created in a destructor. +//! let token =3D unsafe { ::kernel::init::__internal::OnlyCal= lFromDrop::new() }; +//! ::kernel::init::PinnedDrop::drop(pinned, token); +//! } +//! } +//! }; +//! ``` +//! +//! ## `#[pinned_drop]` on `impl PinnedDrop for Foo` +//! +//! This macro is used to implement the `PinnedDrop` trait, since that tra= it is `unsafe` and has an +//! extra parameter that should not be used at all. The macro hides that p= arameter. +//! +//! Here is the `PinnedDrop` impl for `Foo`: +//! +//! ```rust +//! #[pinned_drop] +//! impl PinnedDrop for Foo { +//! fn drop(self: Pin<&mut Self>) { +//! println!("{self:p} is getting dropped."); +//! } +//! } +//! ``` +//! +//! This expands to the following code: +//! +//! ```rust +//! // `unsafe`, full path and the token parameter are added, everything e= lse stays the same. +//! unsafe impl ::kernel::init::PinnedDrop for Foo { +//! fn drop(self: Pin<&mut Self>, _: ::kernel::init::__internal::OnlyC= allFromDrop) { +//! println!("{self:p} is getting dropped."); +//! } +//! } +//! ``` +//! +//! ## `pin_init!` on `Foo` +//! +//! Since we already took a look at `pin_init!` on `Bar`, this section wil= l only explain the +//! differences/new things in the expansion of `pin_init!` on `Foo`: +//! +//! ```rust +//! let a =3D 42; +//! let initializer =3D pin_init!(Foo { +//! a, +//! b <- Bar::new(36), +//! }); +//! ``` +//! +//! This expands to the following code: +//! +//! ```rust +//! let a =3D 42; +//! let initializer =3D { +//! struct __InitOk; +//! let data =3D unsafe { +//! use ::kernel::init::__internal::HasPinData; +//! Foo::__pin_data() +//! }; +//! let init =3D ::kernel::init::__internal::PinData::make_closure::< +//! _, +//! __InitOk, +//! ::core::convert::Infallible, +//! >(data, move |slot| { +//! { +//! struct __InitOk; +//! unsafe { ::core::ptr::write(&raw mut (*slot).a, a) }; +//! let a =3D &unsafe { ::kernel::init::__internal::DropGuard:= :new(&raw mut (*slot).a) }; +//! let b =3D Bar::new(36); +//! // Here we use `data` to access the correct field and requ= ire that `b` is of type +//! // `PinInit, Infallible>`. +//! unsafe { data.b(&raw mut (*slot).b, b)? }; +//! let b =3D &unsafe { ::kernel::init::__internal::DropGuard:= :new(&raw mut (*slot).b) }; +//! +//! #[allow(unreachable_code, clippy::diverging_sub_expression= )] +//! if false { +//! unsafe { +//! ::core::ptr::write( +//! slot, +//! Foo { +//! a: ::core::panic!(), +//! b: ::core::panic!(), +//! }, +//! ); +//! }; +//! } +//! unsafe { ::kernel::init::__internal::DropGuard::forget(a) = }; +//! unsafe { ::kernel::init::__internal::DropGuard::forget(b) = }; +//! } +//! Ok(__InitOk) +//! }); +//! let init =3D move |slot| -> ::core::result::Result<(), ::core::con= vert::Infallible> { +//! init(slot).map(|__InitOk| ()) +//! }; +//! let init =3D unsafe { +//! ::kernel::init::pin_init_from_closure::<_, ::core::convert::In= fallible>(init) +//! }; +//! init +//! }; +//! ``` + +/// Creates a `unsafe impl<...> PinnedDrop for $type` block. +/// +/// See [`PinnedDrop`] for more information. +#[doc(hidden)] +#[macro_export] +macro_rules! __pinned_drop { + ( + @impl_sig($($impl_sig:tt)*), + @impl_body( + $(#[$($attr:tt)*])* + fn drop($($sig:tt)*) { + $($inner:tt)* + } + ), + ) =3D> { + unsafe $($impl_sig)* { + // Inherit all attributes and the type/ident tokens for the si= gnature. + $(#[$($attr)*])* + fn drop($($sig)*, _: $crate::init::__internal::OnlyCallFromDro= p) { + $($inner)* + } + } + } +} /// This macro first parses the struct definition such that it separates p= inned and not pinned /// fields. Afterwards it declares the struct and implement the `PinData` = trait safely. @@ -653,6 +885,38 @@ macro_rules! __pin_data { impl MustNotImplDrop for T {} impl<$($impl_generics)*> MustNotImplDrop for $name<$($ty_generics)= *> where $($whr)* {} + // We also take care to prevent users from writing a useless `Pinn= edDrop` implementation. + // They might implement `PinnedDrop` correctly for the struct, but= forget to give + // `PinnedDrop` as the parameter to `#[pin_data]`. + #[allow(non_camel_case_types)] + trait UselessPinnedDropImpl_you_need_to_specify_PinnedDrop {} + impl + UselessPinnedDropImpl_you_need_to_specify_PinnedDrop for T {} + impl<$($impl_generics)*> + UselessPinnedDropImpl_you_need_to_specify_PinnedDrop for $name= <$($ty_generics)*> + where $($whr)* {} + }; + // When `PinnedDrop` was specified we just implement `Drop` and delega= te. + (drop_prevention: + @name($name:ident), + @impl_generics($($impl_generics:tt)*), + @ty_generics($($ty_generics:tt)*), + @where($($whr:tt)*), + @pinned_drop(PinnedDrop), + ) =3D> { + impl<$($impl_generics)*> ::core::ops::Drop for $name<$($ty_generic= s)*> + where $($whr)* + { + fn drop(&mut self) { + // SAFETY: Since this is a destructor, `self` will not mov= e after this function + // terminates, since it is inaccessible. + let pinned =3D unsafe { ::core::pin::Pin::new_unchecked(se= lf) }; + // SAFETY: Since this is a drop function, we can create th= is token to call the + // pinned destructor of this type. + let token =3D unsafe { $crate::init::__internal::OnlyCallF= romDrop::new() }; + $crate::init::PinnedDrop::drop(pinned, token); + } + } }; // If some other parameter was specified, we emit a readable error. (drop_prevention: diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs index 4def038fe71a..86eb06f2d9fe 100644 --- a/rust/macros/lib.rs +++ b/rust/macros/lib.rs @@ -8,6 +8,7 @@ mod concat_idents; mod helpers; mod module; mod pin_data; +mod pinned_drop; mod vtable; use proc_macro::TokenStream; @@ -180,6 +181,10 @@ pub fn concat_idents(ts: TokenStream) -> TokenStream { /// This macro enables the use of the [`pin_init!`] macro. When pin-initia= lizing a `struct`, /// then `#[pin]` directs the type of intializer that is required. /// +/// If your `struct` implements `Drop`, then you need to add `PinnedDrop` = as arguments to this +/// macro, and change your `Drop` implementation to `PinnedDrop` annotated= with +/// `#[`[`macro@pinned_drop`]`]`, since dropping pinned values requires ex= tra care. +/// /// # Examples /// /// ```rust,ignore @@ -191,9 +196,53 @@ pub fn concat_idents(ts: TokenStream) -> TokenStream { /// } /// ``` /// +/// ```rust,ignore +/// #[pin_data(PinnedDrop)] +/// struct DriverData { +/// #[pin] +/// queue: Mutex>, +/// buf: Box<[u8; 1024 * 1024]>, +/// raw_info: *mut Info, +/// } +/// +/// #[pinned_drop] +/// impl PinnedDrop for DriverData { +/// fn drop(self: Pin<&mut Self>) { +/// unsafe { bindings::destroy_info(self.raw_info) }; +/// } +/// } +/// ``` +/// /// [`pin_init!`]: ../kernel/macro.pin_init.html // ^ cannot use direct link, since `kernel` is not a dependency of `macro= s`. #[proc_macro_attribute] pub fn pin_data(inner: TokenStream, item: TokenStream) -> TokenStream { pin_data::pin_data(inner, item) } + +/// Used to implement `PinnedDrop` safely. +/// +/// Only works on structs that are annotated via `#[`[`macro@pin_data`]`]`. +/// +/// # Examples +/// +/// ```rust,ignore +/// #[pin_data(PinnedDrop)] +/// struct DriverData { +/// #[pin] +/// queue: Mutex>, +/// buf: Box<[u8; 1024 * 1024]>, +/// raw_info: *mut Info, +/// } +/// +/// #[pinned_drop] +/// impl PinnedDrop for DriverData { +/// fn drop(self: Pin<&mut Self>) { +/// unsafe { bindings::destroy_info(self.raw_info) }; +/// } +/// } +/// ``` +#[proc_macro_attribute] +pub fn pinned_drop(args: TokenStream, input: TokenStream) -> TokenStream { + pinned_drop::pinned_drop(args, input) +} diff --git a/rust/macros/pinned_drop.rs b/rust/macros/pinned_drop.rs new file mode 100644 index 000000000000..88fb72b20660 --- /dev/null +++ b/rust/macros/pinned_drop.rs @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: Apache-2.0 OR MIT + +use proc_macro::{TokenStream, TokenTree}; + +pub(crate) fn pinned_drop(_args: TokenStream, input: TokenStream) -> Token= Stream { + let mut toks =3D input.into_iter().collect::>(); + assert!(!toks.is_empty()); + // Ensure that we have an `impl` item. + assert!(matches!(&toks[0], TokenTree::Ident(i) if i.to_string() =3D=3D= "impl")); + // Ensure that we are implementing `PinnedDrop`. + let mut nesting: usize =3D 0; + let mut pinned_drop_idx =3D None; + for (i, tt) in toks.iter().enumerate() { + match tt { + TokenTree::Punct(p) if p.as_char() =3D=3D '<' =3D> { + nesting +=3D 1; + } + TokenTree::Punct(p) if p.as_char() =3D=3D '>' =3D> { + nesting =3D nesting.checked_sub(1).unwrap(); + continue; + } + _ =3D> {} + } + if i >=3D 1 && nesting =3D=3D 0 { + // Found the end of the generics, this should be `PinnedDrop`. + assert!( + matches!(tt, TokenTree::Ident(i) if i.to_string() =3D=3D "= PinnedDrop"), + "expected 'PinnedDrop', found: '{:?}'", + tt + ); + pinned_drop_idx =3D Some(i); + break; + } + } + let idx =3D pinned_drop_idx + .unwrap_or_else(|| panic!("Expected an `impl` block implementing `= PinnedDrop`.")); + // Fully qualify the `PinnedDrop`, as to avoid any tampering. + toks.splice(idx..idx, quote!(::kernel::init::)); + // Take the `{}` body and call the declarative macro. + if let Some(TokenTree::Group(last)) =3D toks.pop() { + let last =3D last.stream(); + quote!(::kernel::__pinned_drop! { + @impl_sig(#(#toks)*), + @impl_body(#last), + }) + } else { + TokenStream::from_iter(toks) + } +} -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 606A4C77B61 for ; Sat, 8 Apr 2023 12:27:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231336AbjDHM1T (ORCPT ); Sat, 8 Apr 2023 08:27:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34950 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230170AbjDHM1D (ORCPT ); Sat, 8 Apr 2023 08:27:03 -0400 Received: from mail-4322.protonmail.ch (mail-4322.protonmail.ch [185.70.43.22]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ADB1910265 for ; Sat, 8 Apr 2023 05:26:41 -0700 (PDT) Date: Sat, 08 Apr 2023 12:26:07 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956777; x=1681215977; bh=hihuEoqXcXK159Nac/9KFKLP5s288mJML8r+SohUUyw=; 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=E9m2cS7KV4pzayV0x3UFSvXPwkPuFOTxjf7VrrKJfjKfc5yeqyVMQWDNad9sjEPY9 i/i2imYoUtt/QcDo11eGzwWdZUdnDl0soDYK46iLcqqVeH+8eaqt1UvAQ94r7IqoK3 7P89MfdrRCaZuMPErjTSYaKtl3q+gAcM6VcpfjrrLzZe8JpZRG9KUuaSIDMRmxvCRp f2D+ZjWeYsAh00Lc8dDvNxDVAOOAR9BLCFo7iRRNPJgaItKKiaG9i5qrrLPLF/0rMh dD/7nlchIqDKhrJsFcULPcuvnlR6opkX0labJxtn1//wWyPkP6Ow/KETN0IdksbXb+ AGwNNy0NmLN0g== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Alice Ryhl , Andreas Hindborg Subject: [PATCH v7 10/15] rust: init: add `stack_pin_init!` macro Message-ID: <20230408122429.1103522-11-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The `stack_pin_init!` macro allows pin-initializing a value on the stack. It accepts a `impl PinInit` to initialize a `T`. It allows propagating any errors via `?` or handling it normally via `match`. Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg Reviewed-by: Gary Guo --- rust/kernel/init.rs | 140 +++++++++++++++++++++++++++++++-- rust/kernel/init/__internal.rs | 57 ++++++++++++++ 2 files changed, 191 insertions(+), 6 deletions(-) diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index 37e8159df24d..99751375e7c8 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -12,7 +12,8 @@ //! //! To initialize a `struct` with an in-place constructor you will need tw= o things: //! - an in-place constructor, -//! - a memory location that can hold your `struct`. +//! - a memory location that can hold your `struct` (this can be the [stac= k], an [`Arc`], +//! [`UniqueArc`], [`Box`] or any other smart pointer that impleme= nts [`InPlaceInit`]). //! //! To get an in-place constructor there are generally three options: //! - directly creating an in-place constructor using the [`pin_init!`] ma= cro, @@ -180,6 +181,7 @@ //! [pinning]: https://doc.rust-lang.org/std/pin/index.html //! [structurally pinned fields]: //! https://doc.rust-lang.org/std/pin/index.html#pinning-is-structural= -for-field +//! [stack]: crate::stack_pin_init //! [`Arc`]: crate::sync::Arc //! [`impl PinInit`]: PinInit //! [`impl PinInit`]: PinInit @@ -202,6 +204,132 @@ pub mod __internal; #[doc(hidden)] pub mod macros; +/// Initialize and pin a type directly on the stack. +/// +/// # Examples +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, stack_pin_init, init::*, sync::Mutex, n= ew_mutex}; +/// # use macros::pin_data; +/// # use core::pin::Pin; +/// #[pin_data] +/// struct Foo { +/// #[pin] +/// a: Mutex, +/// b: Bar, +/// } +/// +/// #[pin_data] +/// struct Bar { +/// x: u32, +/// } +/// +/// stack_pin_init!(let foo =3D pin_init!(Foo { +/// a <- new_mutex!(42), +/// b: Bar { +/// x: 64, +/// }, +/// })); +/// let foo: Pin<&mut Foo> =3D foo; +/// pr_info!("a: {}", &*foo.a.lock()); +/// ``` +/// +/// # Syntax +/// +/// A normal `let` binding with optional type annotation. The expression i= s expected to implement +/// [`PinInit`]/[`Init`] with the error type [`Infallible`]. If you want t= o use a different error +/// type, then use [`stack_try_pin_init!`]. +#[macro_export] +macro_rules! stack_pin_init { + (let $var:ident $(: $t:ty)? =3D $val:expr) =3D> { + let val =3D $val; + let mut $var =3D ::core::pin::pin!($crate::init::__internal::Stack= Init$(::<$t>)?::uninit()); + let mut $var =3D match $crate::init::__internal::StackInit::init($= var, val) { + Ok(res) =3D> res, + Err(x) =3D> { + let x: ::core::convert::Infallible =3D x; + match x {} + } + }; + }; +} + +/// Initialize and pin a type directly on the stack. +/// +/// # Examples +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, stack_try_pin_init, init::*, sync::Mute= x, new_mutex}; +/// # use macros::pin_data; +/// # use core::{alloc::AllocError, pin::Pin}; +/// #[pin_data] +/// struct Foo { +/// #[pin] +/// a: Mutex, +/// b: Box, +/// } +/// +/// struct Bar { +/// x: u32, +/// } +/// +/// stack_try_pin_init!(let foo: Result, AllocError> =3D pin= _init!(Foo { +/// a <- new_mutex!(42), +/// b: Box::try_new(Bar { +/// x: 64, +/// })?, +/// })); +/// let foo =3D foo.unwrap(); +/// pr_info!("a: {}", &*foo.a.lock()); +/// ``` +/// +/// ```rust +/// # #![allow(clippy::disallowed_names, clippy::new_ret_no_self)] +/// # use kernel::{init, pin_init, stack_try_pin_init, init::*, sync::Mute= x, new_mutex}; +/// # use macros::pin_data; +/// # use core::{alloc::AllocError, pin::Pin}; +/// #[pin_data] +/// struct Foo { +/// #[pin] +/// a: Mutex, +/// b: Box, +/// } +/// +/// struct Bar { +/// x: u32, +/// } +/// +/// stack_try_pin_init!(let foo: Pin<&mut Foo> =3D? pin_init!(Foo { +/// a <- new_mutex!(42), +/// b: Box::try_new(Bar { +/// x: 64, +/// })?, +/// })); +/// pr_info!("a: {}", &*foo.a.lock()); +/// # Ok::<_, AllocError>(()) +/// ``` +/// +/// # Syntax +/// +/// A normal `let` binding with optional type annotation. The expression i= s expected to implement +/// [`PinInit`]/[`Init`]. This macro assigns a result to the given variabl= e, adding a `?` after the +/// `=3D` will propagate this error. +#[macro_export] +macro_rules! stack_try_pin_init { + (let $var:ident $(: $t:ty)? =3D $val:expr) =3D> { + let val =3D $val; + let mut $var =3D ::core::pin::pin!($crate::init::__internal::Stack= Init$(::<$t>)?::uninit()); + let mut $var =3D $crate::init::__internal::StackInit::init($var, v= al); + }; + (let $var:ident $(: $t:ty)? =3D? $val:expr) =3D> { + let val =3D $val; + let mut $var =3D ::core::pin::pin!($crate::init::__internal::Stack= Init$(::<$t>)?::uninit()); + let mut $var =3D $crate::init::__internal::StackInit::init($var, v= al)?; + }; +} + /// Construct an in-place, pinned initializer for `struct`s. /// /// This macro defaults the error to [`Infallible`]. If you need [`Error`]= , then use @@ -913,8 +1041,8 @@ 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`]. Use the [`InPlaceInit::pi= n_init`] function of a -/// smart pointer like [`Arc`] on this. +/// be [`Box`], [`Arc`], [`UniqueArc`] or even the stack (see [`s= tack_pin_init!`]). Use the +/// [`InPlaceInit::pin_init`] function of a smart pointer like [`Arc`] = on this. /// /// Also see the [module description](self). /// @@ -949,9 +1077,9 @@ 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`]. 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. +/// be [`Box`], [`Arc`], [`UniqueArc`] or even the stack (see [`s= tack_pin_init!`]). Use the +/// [`InPlaceInit::init`] function of a smart pointer like [`Arc`] on t= his. Because +/// [`PinInit`] is a super trait, you can use every function that ta= kes it as well. /// /// Also see the [module description](self). /// diff --git a/rust/kernel/init/__internal.rs b/rust/kernel/init/__internal.rs index 2445763ba97a..2e643fb2e651 100644 --- a/rust/kernel/init/__internal.rs +++ b/rust/kernel/init/__internal.rs @@ -112,6 +112,63 @@ unsafe impl HasInitData for T { } } +/// Stack initializer helper type. Use [`stack_pin_init`] instead of this = primitive. +/// +/// # Invariants +/// +/// If `self.is_init` is true, then `self.value` is initialized. +/// +/// [`stack_pin_init`]: kernel::stack_pin_init +pub struct StackInit { + value: MaybeUninit, + is_init: bool, +} + +impl Drop for StackInit { + #[inline] + fn drop(&mut self) { + if self.is_init { + // SAFETY: As we are being dropped, we only call this once. An= d since `self.is_init` is + // true, `self.value` is initialized. + unsafe { self.value.assume_init_drop() }; + } + } +} + +impl StackInit { + /// Creates a new [`StackInit`] that is uninitialized. Use [`stack_= pin_init`] instead of this + /// primitive. + /// + /// [`stack_pin_init`]: kernel::stack_pin_init + #[inline] + pub fn uninit() -> Self { + Self { + value: MaybeUninit::uninit(), + is_init: false, + } + } + + /// Initializes the contents and returns the result. + #[inline] + pub fn init(self: Pin<&mut Self>, init: impl PinInit) -> Resu= lt, E> { + // SAFETY: We never move out of `this`. + let this =3D unsafe { Pin::into_inner_unchecked(self) }; + // The value is currently initialized, so it needs to be dropped b= efore we can reuse + // the memory (this is a safety guarantee of `Pin`). + if this.is_init { + this.is_init =3D false; + // SAFETY: `this.is_init` was true and therefore `this.value` = is initialized. + unsafe { this.value.assume_init_drop() }; + } + // SAFETY: The memory slot is valid and this type ensures that it = will stay pinned. + unsafe { init.__pinned_init(this.value.as_mut_ptr())? }; + // INVARIANT: `this.value` is initialized above. + this.is_init =3D true; + // SAFETY: The slot is now pinned, since we will never give access= to `&mut T`. + Ok(unsafe { Pin::new_unchecked(this.value.assume_init_mut()) }) + } +} + /// When a value of this type is dropped, it drops a `T`. /// /// Can be forgotton to prevent the drop. -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 DCBA1C77B6C for ; Sat, 8 Apr 2023 12:27:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231246AbjDHM13 (ORCPT ); Sat, 8 Apr 2023 08:27:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231286AbjDHM1E (ORCPT ); Sat, 8 Apr 2023 08:27:04 -0400 Received: from mail-40133.protonmail.ch (mail-40133.protonmail.ch [185.70.40.133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7050CFF31 for ; Sat, 8 Apr 2023 05:26:43 -0700 (PDT) Date: Sat, 08 Apr 2023 12:26:12 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956785; x=1681215985; bh=Wx+mkXJAMUZ55C6ki8WnDTtKcBxXLup6TKxHAyI1Z5o=; 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=LdlqORiSsNmxoIt4QRBloMSFoxTFyK6z0FRrncl/KmcMtLQebpjtxrOqTAeV+aSOa jOYaEZSgrxlwJHNrTMlLJAPfgiC9ivEVVTp44iEucDd7TetLNo1h+fVtuJRhsxMeWH +vsN4BlH7TRFQxqOBlt/RttSqT3zYaxNhlTRLRoYzN3+zKmvp1M1lF9jZVVtdtBo+/ 3V1dlq0lhm4BJjgVcwUcN2coxWhS/8KFrebSFZYDcnoE7w8RhlXWQqq0CG5vKh5wCe OqxKRf9ZR+DH8ohdsRBy3DnOEQx70CdQLsE/vAvGhmb7hAnkPSrDdq/2z6myjOK6AM 2+sNyW3knxJZg== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Alice Ryhl , Andreas Hindborg Subject: [PATCH v7 11/15] rust: init: add `Zeroable` trait and `init::zeroed` function Message-ID: <20230408122429.1103522-12-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Add the `Zeroable` trait which marks types that can be initialized by writing `0x00` to every byte of the type. Also add the `init::zeroed` function that creates an initializer for a `Zeroable` type that writes `0x00` to every byte. Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Reviewed-by: Andreas Hindborg --- rust/kernel/init.rs | 97 ++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 95 insertions(+), 2 deletions(-) diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index 99751375e7c8..ffd539e2f5ef 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -195,8 +195,14 @@ use crate::{ }; use alloc::boxed::Box; use core::{ - alloc::AllocError, cell::Cell, convert::Infallible, marker::PhantomDat= a, mem::MaybeUninit, - pin::Pin, ptr, + alloc::AllocError, + cell::Cell, + convert::Infallible, + marker::PhantomData, + mem::MaybeUninit, + num::*, + pin::Pin, + ptr::{self, NonNull}, }; #[doc(hidden)] @@ -1323,3 +1329,90 @@ pub unsafe trait PinnedDrop: __internal::HasPinData { /// automatically. fn drop(self: Pin<&mut Self>, only_call_from_drop: __internal::OnlyCal= lFromDrop); } + +/// Marker trait for types that can be initialized by writing just zeroes. +/// +/// # Safety +/// +/// The bit pattern consisting of only zeroes is a valid bit pattern for t= his type. In other words, +/// this is not UB: +/// +/// ```rust,ignore +/// let val: Self =3D unsafe { core::mem::zeroed() }; +/// ``` +pub unsafe trait Zeroable {} + +/// Create a new zeroed T. +/// +/// The returned initializer will write `0x00` to every byte of the given = `slot`. +#[inline] +pub fn zeroed() -> impl Init { + // SAFETY: Because `T: Zeroable`, all bytes zero is a valid bit patter= n for `T` + // and because we write all zeroes, the memory is initialized. + unsafe { + init_from_closure(|slot: *mut T| { + slot.write_bytes(0, 1); + Ok(()) + }) + } +} + +macro_rules! impl_zeroable { + ($($({$($generics:tt)*})? $t:ty, )*) =3D> { + $(unsafe impl$($($generics)*)? Zeroable for $t {})* + }; +} + +impl_zeroable! { + // SAFETY: All primitives that are allowed to be zero. + bool, + char, + u8, u16, u32, u64, u128, usize, + i8, i16, i32, i64, i128, isize, + f32, f64, + + // SAFETY: These are ZSTs, there is nothing to zero. + {} PhantomData, core::marker::PhantomPinned, Infallible,= (), + + // SAFETY: Type is allowed to take any value, including all zeros. + {} MaybeUninit, + + // SAFETY: All zeros is equivalent to `None` (option layout optimizati= on guarantee). + Option, Option, Option, Option, + Option, Option, + Option, Option, Option, Option, + Option, Option, + + // SAFETY: All zeros is equivalent to `None` (option layout optimizati= on guarantee). + // + // In this case we are allowed to use `T: ?Sized`, since all zeros is = the `None` variant. + {} Option>, + {} Option>, + + // SAFETY: `null` pointer is valid. + // + // We cannot use `T: ?Sized`, since the VTABLE pointer part of fat poi= nters is not allowed to be + // null. + // + // When `Pointee` gets stabilized, we could use + // `T: ?Sized where ::Metadata: Zeroable` + {} *mut T, {} *const T, + + // SAFETY: `null` pointer is valid and the metadata part of these fat = pointers is allowed to be + // zero. + {} *mut [T], {} *const [T], *mut str, *const str, + + // SAFETY: `T` is `Zeroable`. + {} [T; N], {} Wrapping, +} + +macro_rules! impl_tuple_zeroable { + ($(,)?) =3D> {}; + ($first:ident, $($t:ident),* $(,)?) =3D> { + // SAFETY: All elements are zeroable and padding can be zero. + unsafe impl<$first: Zeroable, $($t: Zeroable),*> Zeroable for ($fi= rst, $($t),*) {} + impl_tuple_zeroable!($($t),* ,); + } +} + +impl_tuple_zeroable!(A, B, C, D, E, F, G, H, I, J); -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 0C211C77B70 for ; Sat, 8 Apr 2023 12:27:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229898AbjDHM10 (ORCPT ); Sat, 8 Apr 2023 08:27:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231279AbjDHM1E (ORCPT ); Sat, 8 Apr 2023 08:27:04 -0400 Received: from mail-4322.protonmail.ch (mail-4322.protonmail.ch [185.70.43.22]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85D26EFA7 for ; Sat, 8 Apr 2023 05:26:43 -0700 (PDT) Date: Sat, 08 Apr 2023 12:26:17 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956785; x=1681215985; bh=gdEIW+2bBi1IvDlMbXGasea4+ibnJ2p7QwfZLUN+zQA=; 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=pIADBwX0173PFfDAF4r8e2kpng9MOS+XfnmIhLloRySMWkhT+hJFIwVqFCm70SlFk xe8aSwoKIBu9UndZ3hjYZWZab6m4Uw/3fjqRa/aq7mAP6Iia/pJC4YcxaZAvjKrRiM 13cqLprzI5htvsV8Qw03OTT/UxKhiqAYGp2O97EZ5OljSLHnNe1qMAKD87bZNhh3od pmMg0i2DbTTf/ocozFq7m+EFrT3ditbd6+EOODeSDnhZpo50KppqBzNJR0lSSDzOos m2lC4i4s3hwan7lUlWo3DbTS3z1WVJUwSq/VbL7qnN1KTH9fM45gKIMe7/peaq6Ep8 CC1NDL05UAKXg== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Alice Ryhl , Andreas Hindborg Subject: [PATCH v7 12/15] rust: prelude: add `pin-init` API items to prelude Message-ID: <20230408122429.1103522-13-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Add `pin-init` API macros and traits to the prelude. Signed-off-by: Benno Lossin Reviewed-by: Gary Guo Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg --- rust/kernel/prelude.rs | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/rust/kernel/prelude.rs b/rust/kernel/prelude.rs index 0bc1c97e5604..fcdc511d2ce8 100644 --- a/rust/kernel/prelude.rs +++ b/rust/kernel/prelude.rs @@ -18,7 +18,7 @@ pub use core::pin::Pin; pub use alloc::{boxed::Box, vec::Vec}; #[doc(no_inline)] -pub use macros::{module, vtable}; +pub use macros::{module, pin_data, pinned_drop, vtable}; pub use super::build_assert; @@ -27,8 +27,12 @@ pub use super::build_assert; pub use super::dbg; pub use super::{pr_alert, pr_crit, pr_debug, pr_emerg, pr_err, pr_info, pr= _notice, pr_warn}; +pub use super::{init, pin_init, try_init, try_pin_init}; + pub use super::static_assert; pub use super::error::{code::*, Error, Result}; pub use super::{str::CStr, ThisModule}; + +pub use super::init::{InPlaceInit, Init, PinInit}; -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 3FF02C77B61 for ; Sat, 8 Apr 2023 12:27:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231436AbjDHM1h (ORCPT ); Sat, 8 Apr 2023 08:27:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35240 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231168AbjDHM1H (ORCPT ); Sat, 8 Apr 2023 08:27:07 -0400 Received: from mail-4322.protonmail.ch (mail-4322.protonmail.ch [185.70.43.22]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 38B961024E; Sat, 8 Apr 2023 05:26:44 -0700 (PDT) Date: Sat, 08 Apr 2023 12:26:22 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956799; x=1681215999; bh=urI1ZTtOSmU+vvBI5jLuXdUyX7F1fydhihApnsXkfuk=; 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=ZTwQwHt1PVXtCb1HW9Zvd04Z1teTcHsADLp4vudwGRIZkQKxZsedjCCbm7TQog6kE 8Mkdcc3E9RtHlWOgyl0NMb15Vfppir4DYJrxPYeN2JKrCnTyVeESFpQungF7Bx3PvZ ioHU3csjoMbQFcNhvx8FHRP3I5EDALOOQO2qeWnl8WMZXhioRLppeWtWZG7zzL41df mHOzOQbZ5HkE0VeXR4jxJ6lghjJ1N2WUq9UAloiSxAnhW3e+tIAousLOlb6ZxP20WU 9V+/Zbuf5B/mJGS+gdxdNlhi1LZVD+aSFMgCVId33Q2vrviiZMJQxBTNcXRvNgsCoE 2p12dCL4o+AyA== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Alice Ryhl , Andreas Hindborg Subject: [PATCH v7 13/15] rust: types: add `Opaque::ffi_init` Message-ID: <20230408122429.1103522-14-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" This function allows to easily initialize `Opaque` with the pin-init API. `Opaque::ffi_init` takes a closure and returns a pin-initializer. This pin-initiailizer calls the given closure with a pointer to the inner `T`. Co-developed-by: Gary Guo Signed-off-by: Gary Guo Signed-off-by: Benno Lossin Cc: Alice Ryhl Cc: Andreas Hindborg Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg --- rust/kernel/init.rs | 9 +++++++++ rust/kernel/types.rs | 20 ++++++++++++++++++++ 2 files changed, 29 insertions(+) diff --git a/rust/kernel/init.rs b/rust/kernel/init.rs index ffd539e2f5ef..a1298c8bbda0 100644 --- a/rust/kernel/init.rs +++ b/rust/kernel/init.rs @@ -177,6 +177,14 @@ //! } //! ``` //! +//! For the special case where initializing a field is a single FFI-functi= on call that cannot fail, +//! there exist the helper function [`Opaque::ffi_init`]. This function in= itialize a single +//! [`Opaque`] field by just delegating to the supplied closure. You can u= se these in combination +//! with [`pin_init!`]. +//! +//! For more information on how to use [`pin_init_from_closure()`], take a= look at the uses inside +//! the `kernel` crate. The [`sync`] module is a good starting point. +//! //! [`sync`]: kernel::sync //! [pinning]: https://doc.rust-lang.org/std/pin/index.html //! [structurally pinned fields]: @@ -187,6 +195,7 @@ //! [`impl PinInit`]: PinInit //! [`impl Init`]: Init //! [`Opaque`]: kernel::types::Opaque +//! [`Opaque::ffi_init`]: kernel::types::Opaque::ffi_init //! [`pin_data`]: ::macros::pin_data use crate::{ diff --git a/rust/kernel/types.rs b/rust/kernel/types.rs index ff2b2fac951d..3a46ec1a00cd 100644 --- a/rust/kernel/types.rs +++ b/rust/kernel/types.rs @@ -2,6 +2,7 @@ //! Kernel types. +use crate::init::{self, PinInit}; use alloc::boxed::Box; use core::{ cell::UnsafeCell, @@ -234,6 +235,25 @@ impl Opaque { Self(MaybeUninit::uninit()) } + /// Creates a pin-initializer from the given initializer closure. + /// + /// The returned initializer calls the given closure with the pointer = to the inner `T` of this + /// `Opaque`. Since this memory is uninitialized, the closure is not a= llowed to read from it. + /// + /// This function is safe, because the `T` inside of an `Opaque` is al= lowed to be + /// uninitialized. Additionally, access to the inner `T` requires `uns= afe`, so the caller needs + /// to verify at that point that the inner value is valid. + pub fn ffi_init(init_func: impl FnOnce(*mut T)) -> impl PinInit { + // SAFETY: We contain a `MaybeUninit`, so it is OK for the `init_f= unc` to not fully + // initiailize the `T`. + unsafe { + init::pin_init_from_closure::<_, ::core::convert::Infallible>(= move |slot| { + init_func(Self::raw_get(slot)); + Ok(()) + }) + } + } + /// Returns a raw pointer to the opaque data. pub fn get(&self) -> *mut T { UnsafeCell::raw_get(self.0.as_ptr()) -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 81626C77B61 for ; Sat, 8 Apr 2023 12:27:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231305AbjDHM1e (ORCPT ); Sat, 8 Apr 2023 08:27:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35070 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231302AbjDHM1H (ORCPT ); Sat, 8 Apr 2023 08:27:07 -0400 Received: from mail-40133.protonmail.ch (mail-40133.protonmail.ch [185.70.40.133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C4D55113D3 for ; Sat, 8 Apr 2023 05:26:44 -0700 (PDT) Date: Sat, 08 Apr 2023 12:26:27 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956797; x=1681215997; bh=YjWJqyzY7rAxB/8T748G6J4lTdaIt8uzOIDk7TzSA8o=; 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=yJI2kW0bjVdmWEnbNqeuak4+eblElCb6I+DrB69qGiFObCyFe0TNVXjzucDlFNfcK 3bupOg9//vx2vp7dkOSCF/7fSzWBPsZ6rM0VjUUWWqwgg13oNwCa0BPDHmwfDRcAM1 v7j1UjxhQC+1Bhd/tolmiWccVVkd5w8EfZucU5lUATEn29hvrg/wxMfs1xxmIbjcL9 7NDlY7T9dbpyw2VtJf9MIwzk6OrFWsJIAE1ohjuam3cgORImgEicR5MQjUBIKwLUQO 7fMRssbNsGuEAuaium3EN9Put5zzj7l/cq0v+MDqWGwKa2Kmzr/itMLg2LJhzRXouk fnINbVCzhYZjg== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Alice Ryhl , Andreas Hindborg Subject: [PATCH v7 14/15] rust: sync: reduce stack usage of `UniqueArc::try_new_uninit` Message-ID: <20230408122429.1103522-15-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" `UniqueArc::try_new_uninit` calls `Arc::try_new(MaybeUninit::uninit())`. This results in the uninitialized memory being placed on the stack, which may be arbitrarily large due to the generic `T` and thus could cause a stack overflow for large types. Change the implementation to use the pin-init API which enables in-place initialization. In particular it avoids having to first construct and then move the uninitialized memory from the stack into the final location. Signed-off-by: Benno Lossin Reviewed-by: Alice Ryhl Reviewed-by: Gary Guo Reviewed-by: Andreas Hindborg --- rust/kernel/lib.rs | 1 - rust/kernel/sync/arc.rs | 16 +++++++++++++--- 2 files changed, 13 insertions(+), 4 deletions(-) diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index 821bd067151c..2d7606135ef6 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -28,7 +28,6 @@ #[cfg(not(CONFIG_RUST))] compile_error!("Missing kernel configuration for conditional compilation"); -#[allow(unused_extern_crates)] // Allow proc-macros to refer to `::kernel` inside the `kernel` crate (thi= s crate). extern crate self as kernel; diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index 43a53fbe175d..d05caa723718 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -18,7 +18,8 @@ use crate::{ bindings, error::{self, Error}, - init::{InPlaceInit, Init, PinInit}, + init::{self, InPlaceInit, Init, PinInit}, + try_init, types::{ForeignOwnable, Opaque}, }; use alloc::boxed::Box; @@ -30,6 +31,7 @@ use core::{ pin::Pin, ptr::NonNull, }; +use macros::pin_data; /// A reference-counted pointer to an instance of `T`. /// @@ -122,6 +124,7 @@ pub struct Arc { _p: PhantomData>, } +#[pin_data] #[repr(C)] struct ArcInner { refcount: Opaque, @@ -502,9 +505,16 @@ impl UniqueArc { /// Tries to allocate a new [`UniqueArc`] instance whose contents are = not initialised yet. pub fn try_new_uninit() -> Result>, AllocErro= r> { - Ok(UniqueArc::> { + // INVARIANT: The refcount is initialised to a non-zero value. + let inner =3D Box::try_init::(try_init!(ArcInner { + // SAFETY: There are no safety requirements for this FFI call. + refcount: Opaque::new(unsafe { bindings::REFCOUNT_INIT(1) }), + data <- init::uninit::(), + }? AllocError))?; + Ok(UniqueArc { // INVARIANT: The newly-created object has a ref-count of 1. - inner: Arc::try_new(MaybeUninit::uninit())?, + // SAFETY: The pointer from the `Box` is valid. + inner: unsafe { Arc::from_inner(Box::leak(inner).into()) }, }) } } -- 2.39.2 From nobody Sun Feb 8 01:31:22 2026 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 6075AC7619A for ; Sat, 8 Apr 2023 12:27:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231387AbjDHM1y (ORCPT ); Sat, 8 Apr 2023 08:27:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231372AbjDHM1Z (ORCPT ); Sat, 8 Apr 2023 08:27:25 -0400 Received: from mail-4322.protonmail.ch (mail-4322.protonmail.ch [185.70.43.22]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C3AF811678 for ; Sat, 8 Apr 2023 05:26:57 -0700 (PDT) Date: Sat, 08 Apr 2023 12:26:33 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=protonmail.com; s=protonmail3; t=1680956808; x=1681216008; bh=S5ndiOTk444R587cz6eQKsLf+C57xcupLszBquLvesM=; 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=OOrubc/LRQIdYFRctgkFbcNDLiGSXGD0U+/c1+PBFxg5roifhVsFIopbaVNtgQRce 3bNmW7rO4LCRdZaqzSGGI/6Muy+hQ36+5DBOFxNIIRvfAEqk007iyVmWvp9u76zWga VHTHg2hU7/Lonqx0eZeNfhytztlyZXkdOV0DV0fNtq8y9rxLUp3x92Zsr1CxWdlMXm IhznCMtgGp/B8cEIvFL00NjW7t0AEhD4+ZZMjpX32+TtHqtVOxPT+9YUCYH5snDFN+ zhm74iTuqbJGUy4Y+zIfAVAcYvjyQjnzkDkubwF46ysWgAM2km640rDebmaWQlO3Y5 wu81/QyW3onBw== To: Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?utf-8?Q?Bj=C3=B6rn_Roy_Baron?= , Alice Ryhl , Andreas Hindborg From: Benno Lossin Cc: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, Benno Lossin , Alice Ryhl , Andreas Hindborg Subject: [PATCH v7 15/15] rust: sync: add functions for initializing `UniqueArc>` Message-ID: <20230408122429.1103522-16-y86-dev@protonmail.com> In-Reply-To: <20230408122429.1103522-1-y86-dev@protonmail.com> References: <20230408122429.1103522-1-y86-dev@protonmail.com> Feedback-ID: 40624463:user:proton MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Add two functions `init_with` and `pin_init_with` to `UniqueArc>` to initialize the memory of already allocated `UniqueArc`s. This is useful when you want to allocate memory check some condition inside of a context where allocation is forbidden and then conditionally initialize an object. Signed-off-by: Benno Lossin Reviewed-by: Gary Guo Reviewed-by: Alice Ryhl Reviewed-by: Andreas Hindborg --- rust/kernel/sync/arc.rs | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/rust/kernel/sync/arc.rs b/rust/kernel/sync/arc.rs index d05caa723718..d1a79cce5e54 100644 --- a/rust/kernel/sync/arc.rs +++ b/rust/kernel/sync/arc.rs @@ -541,6 +541,30 @@ impl UniqueArc> { inner: unsafe { Arc::from_inner(inner.cast()) }, } } + + /// Initialize `self` using the given initializer. + pub fn init_with(mut self, init: impl Init) -> core::result::= Result, E> { + // SAFETY: The supplied pointer is valid for initialization. + match unsafe { init.__init(self.as_mut_ptr()) } { + // SAFETY: Initialization completed successfully. + Ok(()) =3D> Ok(unsafe { self.assume_init() }), + Err(err) =3D> Err(err), + } + } + + /// Pin-initialize `self` using the given pin-initializer. + pub fn pin_init_with( + mut self, + init: impl PinInit, + ) -> core::result::Result>, E> { + // SAFETY: The supplied pointer is valid for initialization and we= will later pin the value + // to ensure it does not move. + match unsafe { init.__pinned_init(self.as_mut_ptr()) } { + // SAFETY: Initialization completed successfully. + Ok(()) =3D> Ok(unsafe { self.assume_init() }.into()), + Err(err) =3D> Err(err), + } + } } impl From> for Pin> { -- 2.39.2