From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4E5C6C77B61 for ; Sun, 9 Apr 2023 16:47:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229450AbjDIQrr (ORCPT ); Sun, 9 Apr 2023 12:47:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57654 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229485AbjDIQro (ORCPT ); Sun, 9 Apr 2023 12:47:44 -0400 Received: from mail-oa1-x35.google.com (mail-oa1-x35.google.com [IPv6:2001:4860:4864:20::35]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3711B3C30; Sun, 9 Apr 2023 09:47:39 -0700 (PDT) Received: by mail-oa1-x35.google.com with SMTP id 586e51a60fabf-183f4efa98aso9782369fac.2; Sun, 09 Apr 2023 09:47:39 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1681058858; h=content-transfer-encoding:in-reply-to:content-language:references :cc:to:subject:from:user-agent:mime-version:date:message-id:from:to :cc:subject:date:message-id:reply-to; bh=deA2mG9P5Qv3+gcJzpwWMdasscdax3dDxfQYVedCOVY=; b=ThOz8KWz4qaPGD5i8q2f+g6qAC3p4ylA+XwTKBmZObncjG+iTN/ykrhTtTxNy/5lXM b8NVEiem01hj8FxjdVu2mAmXbe+sAlbUnwkt0zmAipauFOdcI6/QhOxDjMjvhINyvnZO NFdld0vIHVnz7kG0l2i7U+MvHrAjh9efJZR7ZBpsGXh+GJuFfhkHOZhnLsrN9Puv18mH e6Wo4pAVOYLoAiR+EBPKiRs+ctkxOnlXWZyacs7FMXbpCE8SIzhaSoZKyaVcj8gC8erg ocbbeX/Lxrllap4ODS/YQomazLEr7q79RFpViWN8wYZwwCNlQ8i6ghCgB+Dhw/x05D8K IEWg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1681058858; h=content-transfer-encoding:in-reply-to:content-language:references :cc:to:subject:from:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=deA2mG9P5Qv3+gcJzpwWMdasscdax3dDxfQYVedCOVY=; b=Kz9v+AcXQb5bvTgbcMb2HzCi2lqgp+6euwtixE+BVf9oScWvvmKXu9go5FUvGXgCwL 8WJta8UdGu+AQ6At3A2xRiKFT1iYcudNnpGph7uRTreqRBugF6hD5cxK9wnqUpn/9Ynz tWFETrdZLt+/QhecsnwKS7G2Q5cQ6IULzXWcyvISdlohioWyqKSQ/SDAcdJsWLSaNcbO 993q9SnJaNL8IlaIWd+TlpB1ABzz/EYXfVtB+SUlljG11Ku/l10g8l3G0kNe/Gh/FTAJ 8VAEpq7WFEWG0NsunD8Tmv6uGUgALF+zd9/tMlrh67K9Lv6uVr/ugJC5N0xe03Qviv6e A/3w== X-Gm-Message-State: AAQBX9f7N57FQh9SFK8SFsn54XfY/jXekSyloO/1nRB4mf8HZ71JQp7b T2nar2fs9r9un8tqaj0nDfY= X-Google-Smtp-Source: AKy350aIoRM3P+1KsU7TjpArMkRj0cUkiHp2+VtNTNb2UjmOJoAeIV56CrKY8AY5An8z6hvQS5p+Sg== X-Received: by 2002:a05:6870:b003:b0:177:80e4:9a52 with SMTP id y3-20020a056870b00300b0017780e49a52mr4372910oae.6.1681058858329; Sun, 09 Apr 2023 09:47:38 -0700 (PDT) Received: from [192.168.54.90] (static.220.238.itcsa.net. [190.15.220.238]) by smtp.gmail.com with ESMTPSA id yx21-20020a056871251500b001842bb0a01csm1396748oab.27.2023.04.09.09.47.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 09 Apr 2023 09:47:37 -0700 (PDT) Message-ID: <3a08f406-c71e-c012-a8f3-c2048952e195@gmail.com> Date: Sun, 9 Apr 2023 13:47:34 -0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.1 From: Martin Rodriguez Reboredo Subject: Re: [PATCH v3 03/13] rust: lock: introduce `Mutex` To: Wedson Almeida Filho , rust-for-linux@vger.kernel.org Cc: Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?UTF-8?Q?Bj=c3=b6rn_Roy_Baron?= , linux-kernel@vger.kernel.org, Wedson Almeida Filho , Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long References: <20230408075340.25237-1-wedsonaf@gmail.com> <20230408075340.25237-3-wedsonaf@gmail.com> Content-Language: en-US In-Reply-To: <20230408075340.25237-3-wedsonaf@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: rust-for-linux@vger.kernel.org On 4/8/23 04:53, Wedson Almeida Filho wrote: > From: Wedson Almeida Filho > > This is the `struct mutex` lock backend and allows Rust code to use the > kernel mutex idiomatically. > > Cc: Peter Zijlstra > Cc: Ingo Molnar > Cc: Will Deacon > Cc: Waiman Long > Signed-off-by: Wedson Almeida Filho > --- > v1 -> v2: No changes > v2 -> v3: No changes > > rust/helpers.c | 7 ++ > rust/kernel/sync.rs | 1 + > rust/kernel/sync/lock.rs | 2 + > rust/kernel/sync/lock/mutex.rs | 118 +++++++++++++++++++++++++++++++++ > 4 files changed, 128 insertions(+) > create mode 100644 rust/kernel/sync/lock/mutex.rs > > diff --git a/rust/helpers.c b/rust/helpers.c > index 09a4d93f9d62..3010a2ec26e2 100644 > --- a/rust/helpers.c > +++ b/rust/helpers.c > @@ -21,6 +21,7 @@ > #include > #include > #include > +#include > > __noreturn void rust_helper_BUG(void) > { > @@ -28,6 +29,12 @@ __noreturn void rust_helper_BUG(void) > } > EXPORT_SYMBOL_GPL(rust_helper_BUG); > > +void rust_helper_mutex_lock(struct mutex *lock) > +{ > + mutex_lock(lock); > +} > +EXPORT_SYMBOL_GPL(rust_helper_mutex_lock); > + > refcount_t rust_helper_REFCOUNT_INIT(int n) > { > return (refcount_t)REFCOUNT_INIT(n); > diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs > index 81b0998eaa18..693f0b7f4e4f 100644 > --- a/rust/kernel/sync.rs > +++ b/rust/kernel/sync.rs > @@ -11,6 +11,7 @@ mod arc; > pub mod lock; > > pub use arc::{Arc, ArcBorrow, UniqueArc}; > +pub use lock::mutex::Mutex; > > /// Represents a lockdep class. It's a wrapper around C's `lock_class_key`. > #[repr(transparent)] > diff --git a/rust/kernel/sync/lock.rs b/rust/kernel/sync/lock.rs > index 3fa4eefde740..86669f771ee0 100644 > --- a/rust/kernel/sync/lock.rs > +++ b/rust/kernel/sync/lock.rs > @@ -10,6 +10,8 @@ use crate::{bindings, init::PinInit, pin_init, str::CStr, types::Opaque}; > use core::{cell::UnsafeCell, marker::PhantomData, marker::PhantomPinned}; > use macros::pin_data; > > +pub mod mutex; > + > /// The "backend" of a lock. > /// > /// It is the actual implementation of the lock, without the need to repeat patterns used in all > diff --git a/rust/kernel/sync/lock/mutex.rs b/rust/kernel/sync/lock/mutex.rs > new file mode 100644 > index 000000000000..923472f04af4 > --- /dev/null > +++ b/rust/kernel/sync/lock/mutex.rs > @@ -0,0 +1,118 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +//! A kernel mutex. > +//! > +//! This module allows Rust code to use the kernel's `struct mutex`. > + > +use crate::bindings; > + > +/// Creates a [`Mutex`] initialiser with the given name and a newly-created lock class. > +/// > +/// It uses the name if one is given, otherwise it generates one based on the file name and line > +/// number. > +#[macro_export] > +macro_rules! new_mutex { > + ($inner:expr $(, $name:literal)? $(,)?) => { > + $crate::sync::Mutex::new( > + $inner, $crate::optional_name!($($name)?), $crate::static_lock_class!()) > + }; > +} > + > +/// A mutual exclusion primitive. > +/// > +/// Exposes the kernel's [`struct mutex`]. When multiple threads attempt to lock the same mutex, > +/// only one at a time is allowed to progress, the others will block (sleep) until the mutex is > +/// unlocked, at which point another thread will be allowed to wake up and make progress. > +/// > +/// Since it may block, [`Mutex`] needs to be used with care in atomic contexts. > +/// > +/// Instances of [`Mutex`] need a lock class and to be pinned. The recommended way to create such > +/// instances is with the [`pin_init`](crate::pin_init) and [`new_mutex`] macros. > +/// > +/// # Examples > +/// > +/// The following example shows how to declare, allocate and initialise a struct (`Example`) that > +/// contains an inner struct (`Inner`) that is protected by a mutex. > +/// > +/// ``` > +/// use kernel::{init::InPlaceInit, init::PinInit, new_mutex, pin_init, sync::Mutex}; > +/// > +/// struct Inner { > +/// a: u32, > +/// b: u32, > +/// } > +/// > +/// #[pin_data] > +/// struct Example { > +/// c: u32, > +/// #[pin] > +/// d: Mutex, > +/// } > +/// > +/// impl Example { > +/// fn new() -> impl PinInit { > +/// pin_init!(Self { > +/// c: 10, > +/// d <- new_mutex!(Inner { a: 20, b: 30 }), > +/// }) > +/// } > +/// } > +/// > +/// // Allocate a boxed `Example`. > +/// let e = Box::pin_init(Example::new())?; > +/// assert_eq!(e.c, 10); > +/// assert_eq!(e.d.lock().a, 20); > +/// assert_eq!(e.d.lock().b, 30); > +/// ``` > +/// > +/// The following example shows how to use interior mutability to modify the contents of a struct > +/// protected by a mutex despite only having a shared reference: > +/// > +/// ``` > +/// use kernel::sync::Mutex; > +/// > +/// struct Example { > +/// a: u32, > +/// b: u32, > +/// } > +/// > +/// fn example(m: &Mutex) { > +/// let mut guard = m.lock(); > +/// guard.a += 10; > +/// guard.b += 20; > +/// } > +/// ``` > +/// > +/// [`struct mutex`]: ../../../../include/linux/mutex.h > +pub type Mutex = super::Lock; > + > +/// A kernel `struct mutex` lock backend. > +pub struct MutexBackend; > + > +// SAFETY: The underlying kernel `struct mutex` object ensures mutual exclusion. > +unsafe impl super::Backend for MutexBackend { > + type State = bindings::mutex; > + type GuardState = (); > + > + unsafe fn init( > + ptr: *mut Self::State, > + name: *const core::ffi::c_char, > + key: *mut bindings::lock_class_key, > + ) { > + // SAFETY: The safety requirements ensure that `ptr` is valid for writes, and `name` and > + // `key` are valid for read indefinitely. > + unsafe { bindings::__mutex_init(ptr, name, key) } > + } > + > + unsafe fn lock(ptr: *mut Self::State) -> Self::GuardState { > + // SAFETY: The safety requirements of this function ensure that `ptr` points to valid > + // memory, and that it has been initialised before. > + unsafe { bindings::mutex_lock(ptr) }; > + } > + > + unsafe fn unlock(ptr: *mut Self::State, _guard_state: &Self::GuardState) { > + // SAFETY: The safety requirements of this function ensure that `ptr` is valid and that the > + // caller is the owner of the mutex. > + unsafe { bindings::mutex_unlock(ptr) }; > + } > +} Reviewed-by: Martin Rodriguez Reboredo