From nobody Wed Dec 17 13:30:27 2025 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 8355DC6FD18 for ; Wed, 19 Apr 2023 17:45:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233537AbjDSRpP (ORCPT ); Wed, 19 Apr 2023 13:45:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233263AbjDSRpC (ORCPT ); Wed, 19 Apr 2023 13:45:02 -0400 Received: from mail-oa1-x36.google.com (mail-oa1-x36.google.com [IPv6:2001:4860:4864:20::36]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8E09472A0; Wed, 19 Apr 2023 10:44:51 -0700 (PDT) Received: by mail-oa1-x36.google.com with SMTP id 586e51a60fabf-18777914805so297825fac.1; Wed, 19 Apr 2023 10:44:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1681926291; x=1684518291; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=+ROxF1m2E3+7Rhy4bCnkyAJPHzO/m6/QTfEY4C+9JAc=; b=AjM8E+kpHI+BtRFpFjJD8UQlP+oaY81H6l5eDMl0Zh+vOMI6VbCELcfvLZIJHrBsO9 8tFoiW/pbq8FdbtECcdG+zZCT1DBZlGsuXLstQIEQ1S20pKtmgd3tthlBLbNT0iFPX4H 0fJQfQAtLzuMNHTUXpo1lmey/1ThxoxRHwvcWIlBSsHKAGIwgJT4fWvCjDqkagQ9l02f 7TmlFGkxthw0Sx3/MqCT2DyK1RBvoUzpAszVYoX5oJKo8P2P55af7/5aW8lqOI5ySlBO ABJWmDdMfPxx8g4aJiiA/+/i+9bDNHdm0JqNSqIvmEo6oMXceazrT+loPSgQ3ELOQW5F 8sVw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681926291; x=1684518291; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=+ROxF1m2E3+7Rhy4bCnkyAJPHzO/m6/QTfEY4C+9JAc=; b=E76JXRM7DUgFMKBKowpOzucLIX335nMlPM7xjznb/0xCka7XkB7ds7qoxIl6t6iU31 cKkrpL2VJBGP9y6oL/t76Vvv6diEKcMZWj6jL/qCmPMktsUpnlTRHfb7ZRuLwYfI45GZ O8SCdEnhFb1nJcwzJWlqKjG7c8ZaFtvHMIloA8KEHv2CjiEmnUNfFJ76tKx09ePAJg+I BWdMBPgh6CFRrp0WXBzqJDHBW8jaC+kTzGP+VY6T4K4j3Uq9fiz2ufF6iLvFmM4Vg4QE U06eNPlW625QTMtbMgOS1TIH9GoeRYlqHrlczqm3JnJv0iM11s/wKdog5JGM2bVY4zCf qmSQ== X-Gm-Message-State: AAQBX9etjOHUuoMXKxR2rm72UtKtNw2OmZkAf0eny+8K6qsXc4vw4m/y OgTfE2VFnmeLfS9kF6soEXP5n0PRVCk= X-Google-Smtp-Source: AKy350YmNJ+gaYDWISkFj7OVb0ZtcGGu6qc0dfvsLYGxq02UG/b+4kbd6TPguNtreqZbDycVumqXXg== X-Received: by 2002:a05:6870:c0d0:b0:184:4216:4cb4 with SMTP id e16-20020a056870c0d000b0018442164cb4mr232989oad.21.1681926290815; Wed, 19 Apr 2023 10:44:50 -0700 (PDT) Received: from wedsonaf-dev.home.lan ([189.124.190.154]) by smtp.googlemail.com with ESMTPSA id du3-20020a0568703a0300b001723a2e84b6sm6987585oab.6.2023.04.19.10.44.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Apr 2023 10:44:50 -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?Bj=C3=B6rn=20Roy=20Baron?= , linux-kernel@vger.kernel.org, Wedson Almeida Filho , Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long , Martin Rodriguez Reboredo Subject: [PATCH v4.1] rust: lock: introduce `SpinLock` Date: Wed, 19 Apr 2023 14:44:26 -0300 Message-Id: <20230419174426.132207-1-wedsonaf@gmail.com> X-Mailer: git-send-email 2.34.1 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: 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 Reviewed-by: Martin Rodriguez Reboredo Signed-off-by: Wedson Almeida Filho --- v1 -> v2: No changes v2 -> v3: No changes v3 -> v4: No changes v4 -> v4.1: - Use __raw_spin_lock_init instead of spin_lock_init_with_key=20 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 86af099d2d66..1af5fcbd7f72 100644 --- a/rust/helpers.c +++ b/rust/helpers.c @@ -23,6 +23,7 @@ #include #include #include +#include =20 __noreturn void rust_helper_BUG(void) { @@ -36,6 +37,29 @@ void rust_helper_mutex_lock(struct mutex *lock) } EXPORT_SYMBOL_GPL(rust_helper_mutex_lock); =20 +void rust_helper___spin_lock_init(spinlock_t *lock, const char *name, + struct lock_class_key *key) +{ +#ifdef CONFIG_DEBUG_SPINLOCK + __raw_spin_lock_init(spinlock_check(lock), name, key, LD_WAIT_CONFIG); +#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 693f0b7f4e4f..c997ff7e951e 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -11,7 +11,7 @@ mod arc; pub mod lock; =20 pub use arc::{Arc, ArcBorrow, UniqueArc}; -pub use lock::mutex::Mutex; +pub use lock::{mutex::Mutex, spinlock::SpinLock}; =20 /// 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 98de109d9e40..08adc3747033 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; =20 pub mod mutex; +pub mod spinlock; =20 /// The "backend" of a lock. /// diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spin= lock.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-cre= ated 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)? $(,)?) =3D> { + $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 loc= k 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 reco= mmended 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 =3D 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 t= he 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 =3D m.lock(); +/// guard.a +=3D 10; +/// guard.b +=3D 20; +/// } +/// ``` +/// +/// [`spinlock_t`]: ../../../../include/linux/spinlock.h +pub type SpinLock =3D super::Lock; + +/// A kernel `spinlock_t` lock backend. +pub struct SpinLockBackend; + +// SAFETY: The underlying kernel `spinlock_t` object ensures mutual exclus= ion. +unsafe impl super::Backend for SpinLockBackend { + type State =3D bindings::spinlock_t; + type GuardState =3D (); + + 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 `p= tr` 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::GuardStat= e) { + // SAFETY: The safety requirements of this function ensure that `p= tr` is valid and that the + // caller is the owner of the mutex. + unsafe { bindings::spin_unlock(ptr) } + } +} --=20 2.34.1