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[2620:137:e000::1:20]) by mx.google.com with ESMTP id go8-20020a1709070d8800b00947de40ef34si5916959ejc.440.2023.04.08.01.04.10; Sat, 08 Apr 2023 01:04:34 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20210112 header.b=P+MG41Bt; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230029AbjDHHyK (ORCPT + 99 others); Sat, 8 Apr 2023 03:54:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229916AbjDHHyC (ORCPT ); Sat, 8 Apr 2023 03:54:02 -0400 Received: from mail-oi1-x236.google.com (mail-oi1-x236.google.com [IPv6:2607:f8b0:4864:20::236]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 85042E18D; Sat, 8 Apr 2023 00:54:01 -0700 (PDT) Received: by mail-oi1-x236.google.com with SMTP id f14so18830837oiw.10; Sat, 08 Apr 2023 00:54:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1680940441; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=VdK7JrX/rQUp7e2zQbiDuLx9MtRcIQVTQroy9sLX/Ho=; b=P+MG41Bt1xeXQU4EkCmu4OXlVwPAqqYePd9ipkYQyF+tlD42dm9J/Oju/lEpLN7Y9S YW4v+cRNoOYiYOp+t8GhpEaFox3UPyg6W/qveFG+GdjDfEUVvTT4ZyxUzupfNuhAKgc5 BI2OSKfL6Tlf9IzOE6gNmWgFybq9zZJJSS6HjIVNLr6Cf9P7pGtC1EnD5JSgN89BFHGj j/nFioLidzT9T5He7N85T19e+Qip75i8u4vlfkj8hL5wBeVx10ZGwJG5H4mzKCiOYaer rVrSwJqCjj6yooyC2kV30Eqz7kdGl5ONgXGujfc72VJgSn46U4iTjZWBaLR4N6vCnWGX ynAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680940441; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=VdK7JrX/rQUp7e2zQbiDuLx9MtRcIQVTQroy9sLX/Ho=; b=7xkiH603WhyF32JSjR48QWi8hVP9c6SXtVb084McwpUAMcMjr4nDBRXiW2muPZeofy qo6R5ZDRKiZU9qzOpWKnSuPPUeXA3AmKnIEneYvBn4ESeFEANgJ9VCrl6g3eMVa9TgjQ HKhGTzdk8kxSXRAPe35Uz1wiCcvnZ+tCuCngHuAYOHXdE8xqOTTUM432j3s3qjHr6Tdy GUhl7HnDbBglIICtxJyz+bZkxRzVD+q+c/JItVx4BoUsXBsVxkc66VKnCcM59QhwiHzY YqO6/fuAJeFV6XwXNB09XOQPhTOQhUNkaKO8cMy27Mpmq3iTUEUsyZS93L/HSVZNZqu5 z+LQ== X-Gm-Message-State: AAQBX9cLa+os2wgbGgyWsTSppNgVoIfso0Jh+Jdk3q4jCvIQ20wE5Kao 840U3t9CjUJv7ul85+vRgmaD62ONEfst2g== X-Received: by 2002:a05:6808:1396:b0:386:c879:d3ae with SMTP id c22-20020a056808139600b00386c879d3aemr7582840oiw.10.1680940440748; Sat, 08 Apr 2023 00:54:00 -0700 (PDT) Received: from wedsonaf-dev.home.lan ([189.124.190.154]) by smtp.googlemail.com with ESMTPSA id o6-20020a4a9586000000b0051ffe0fe11bsm2435175ooi.6.2023.04.08.00.53.57 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 08 Apr 2023 00:54:00 -0700 (PDT) From: Wedson Almeida Filho To: rust-for-linux@vger.kernel.org Cc: Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?B?= =?utf-8?q?j=C3=B6rn_Roy_Baron?= , linux-kernel@vger.kernel.org, Wedson Almeida Filho , Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long Subject: [PATCH v3 03/13] rust: lock: introduce `Mutex` Date: Sat, 8 Apr 2023 04:53:30 -0300 Message-Id: <20230408075340.25237-3-wedsonaf@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230408075340.25237-1-wedsonaf@gmail.com> References: <20230408075340.25237-1-wedsonaf@gmail.com> MIME-Version: 1.0 X-Spam-Status: No, score=-0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1762594467722240276?= X-GMAIL-MSGID: =?utf-8?q?1762594467722240276?= 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 Reviewed-by: Martin Rodriguez Reboredo --- 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) }; + } +}