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[2620:137:e000::1:20]) by mx.google.com with ESMTP id z13-20020a170906814d00b00939f6198089si11373755ejw.859.2023.04.05.10.53.29; Wed, 05 Apr 2023 10:53:53 -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="j/E0lBnN"; 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 S232400AbjDERwQ (ORCPT + 99 others); Wed, 5 Apr 2023 13:52:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38952 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232224AbjDERwL (ORCPT ); Wed, 5 Apr 2023 13:52:11 -0400 Received: from mail-oi1-x235.google.com (mail-oi1-x235.google.com [IPv6:2607:f8b0:4864:20::235]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 05583729F; Wed, 5 Apr 2023 10:52:04 -0700 (PDT) Received: by mail-oi1-x235.google.com with SMTP id bi31so27219302oib.9; Wed, 05 Apr 2023 10:52:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1680717124; 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=Rc5vjhZEE+1JaJ4UEjyTi+WD/ZvoFrZiKdNDQzYgVUE=; b=j/E0lBnN3bsNNdU6EfTb9bTo+6dfMsVCWvhvg/Jv1LGwm77sY12q+idQBNN98xPCfc Ms1D+qiPvYQMBMy0HPe+wXIBo4deBoopUtZ1vGzUcP4Omoa1+0568ay9+lrL8aj5f/Yn rpA8qEOuGnGstfHQKNwsVWzkdirj1+eJA8UbOJgp37Mk20XaiQKXfVxj8ajgiFcztxDI tS/o0qi/oZnWuUv3KQR+9HIWdRkhs66slyVID4XKC7TbFb42zx1xiNRIWRqqX7foP6h3 jzuvQK68oGdMH0DWH24Pg4IpD+5DnOFRMf1b3zQ1FbJRrOrmGd3IQ9OldNCX66AJR/GV hceQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680717124; 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=Rc5vjhZEE+1JaJ4UEjyTi+WD/ZvoFrZiKdNDQzYgVUE=; b=viCRDQG7a4XDwkrq7jnxWkNVjHRvxbLxa1BXESWnxQf8PD3zxxmx9djS5w0CBn4Axk aVn2jIHst3FWQQxKucnWUI5Pk1qhF/uAllyHnhuLoP6OiqSK6h3vnmiculhoHPMuVVrj YZ+/csf/19l+Te3JCQaf/ys7jzILTLd/gjZy507+6P++xUdKvAVZh1Spx5LkJ0KvE57B zmaQn++LR6Ogj2zkaA9sGlGCp7zw+2kLqjDsJl/matm94qU+K9DOpCcIoHYQrGET86xy w0waYWxaOGIZvjbM9yMLHVLon+Z7f8BgI4uPn2wyU3RzGkdDOZQvaFMTqPyibjGBKyM0 b2nA== X-Gm-Message-State: AAQBX9c3EczyhjwVpXQ+Csex/17vjH0R7DzwqPW3266CLgmcwxWEpnp0 egwUZ2ifuRz6qq3XAKhiI/G1R2QgjlLE4Q== X-Received: by 2002:a05:6808:179d:b0:378:a144:f7ad with SMTP id bg29-20020a056808179d00b00378a144f7admr1777799oib.17.1680717123367; Wed, 05 Apr 2023 10:52:03 -0700 (PDT) Received: from wedsonaf-dev.home.lan ([189.124.190.154]) by smtp.googlemail.com with ESMTPSA id w185-20020aca62c2000000b003896e31867esm6604045oib.49.2023.04.05.10.51.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Apr 2023 10:52:03 -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 v2 05/13] rust: lock: introduce `SpinLock` Date: Wed, 5 Apr 2023 14:51:03 -0300 Message-Id: <20230405175111.5974-5-wedsonaf@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230405175111.5974-1-wedsonaf@gmail.com> References: <20230405175111.5974-1-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?1762359753719251347?= X-GMAIL-MSGID: =?utf-8?q?1762359753719251347?= From: Wedson Almeida Filho This is the `spinlock_t` lock backend and allows Rust code to use the kernel spinlock idiomatically. Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Will Deacon Cc: Waiman Long Signed-off-by: Wedson Almeida Filho --- v1 -> v2: No changes rust/helpers.c | 24 +++++++ rust/kernel/sync.rs | 2 +- rust/kernel/sync/lock.rs | 1 + rust/kernel/sync/lock/spinlock.rs | 116 ++++++++++++++++++++++++++++++ 4 files changed, 142 insertions(+), 1 deletion(-) create mode 100644 rust/kernel/sync/lock/spinlock.rs diff --git a/rust/helpers.c b/rust/helpers.c index 3010a2ec26e2..05694e3f8f70 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -22,6 +22,7 @@ #include #include #include +#include __noreturn void rust_helper_BUG(void) { @@ -35,6 +36,29 @@ void rust_helper_mutex_lock(struct mutex *lock) } EXPORT_SYMBOL_GPL(rust_helper_mutex_lock); +void rust_helper___spin_lock_init(spinlock_t *lock, const char *name, + struct lock_class_key *key) +{ +#ifdef CONFIG_DEBUG_SPINLOCK + spin_lock_init_with_key(lock, name, key); +#else + spin_lock_init(lock); +#endif +} +EXPORT_SYMBOL_GPL(rust_helper___spin_lock_init); + +void rust_helper_spin_lock(spinlock_t *lock) +{ + spin_lock(lock); +} +EXPORT_SYMBOL_GPL(rust_helper_spin_lock); + +void rust_helper_spin_unlock(spinlock_t *lock) +{ + spin_unlock(lock); +} +EXPORT_SYMBOL_GPL(rust_helper_spin_unlock); + 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 9ff116b2eebe..ed07437d7d55 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -11,7 +11,7 @@ mod arc; pub mod lock; pub use arc::{Arc, ArcBorrow, UniqueArc}; -pub use lock::mutex::Mutex; +pub use lock::{mutex::Mutex, spinlock::SpinLock}; /// 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 cec1d68bab86..bca9af2a9a5a 100644 --- a/rust/kernel/sync/lock.rs +++ b/rust/kernel/sync/lock.rs @@ -11,6 +11,7 @@ use core::{cell::UnsafeCell, marker::PhantomData, marker::PhantomPinned}; use macros::pin_data; pub mod mutex; +pub mod spinlock; /// The "backend" of a lock. /// diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs new file mode 100644 index 000000000000..a52d20fc9755 --- /dev/null +++ b/rust/kernel/sync/lock/spinlock.rs @@ -0,0 +1,116 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! A kernel spinlock. +//! +//! This module allows Rust code to use the kernel's `spinlock_t`. + +use crate::bindings; + +/// Creates a [`SpinLock`] 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_spinlock { + ($inner:expr $(, $name:literal)? $(,)?) => { + $crate::sync::SpinLock::new( + $inner, $crate::optional_name!($($name)?), $crate::static_lock_class!()) + }; +} + +/// A spinlock. +/// +/// Exposes the kernel's [`spinlock_t`]. When multiple CPUs attempt to lock the same spinlock, only +/// one at a time is allowed to progress, the others will block (spinning) until the spinlock is +/// unlocked, at which point another CPU will be allowed to make progress. +/// +/// Instances of [`SpinLock`] 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_spinlock`] 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 spinlock. +/// +/// ``` +/// use kernel::{init::InPlaceInit, init::PinInit, new_spinlock, pin_init, sync::SpinLock}; +/// +/// struct Inner { +/// a: u32, +/// b: u32, +/// } +/// +/// #[pin_data] +/// struct Example { +/// c: u32, +/// #[pin] +/// d: SpinLock, +/// } +/// +/// impl Example { +/// fn new() -> impl PinInit { +/// pin_init!(Self { +/// c: 10, +/// d <- new_spinlock!(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 spinlock despite only having a shared reference: +/// +/// ``` +/// use kernel::sync::SpinLock; +/// +/// struct Example { +/// a: u32, +/// b: u32, +/// } +/// +/// fn example(m: &SpinLock) { +/// let mut guard = m.lock(); +/// guard.a += 10; +/// guard.b += 20; +/// } +/// ``` +/// +/// [`spinlock_t`]: ../../../../include/linux/spinlock.h +pub type SpinLock = super::Lock; + +/// A kernel `spinlock_t` lock backend. +pub struct SpinLockBackend; + +// SAFETY: The underlying kernel `spinlock_t` object ensures mutual exclusion. +unsafe impl super::Backend for SpinLockBackend { + type State = bindings::spinlock_t; + 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::__spin_lock_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::spin_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::spin_unlock(ptr) } + } +}