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 B8A04C77B6C for ; Sat, 8 Apr 2023 07:54:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230171AbjDHHyg (ORCPT ); Sat, 8 Apr 2023 03:54:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59274 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230024AbjDHHyM (ORCPT ); Sat, 8 Apr 2023 03:54:12 -0400 Received: from mail-oo1-xc32.google.com (mail-oo1-xc32.google.com [IPv6:2607:f8b0:4864:20::c32]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D8FACFF0B; Sat, 8 Apr 2023 00:54:08 -0700 (PDT) Received: by mail-oo1-xc32.google.com with SMTP id s19-20020a4adb93000000b00540fa505f2dso3510443oou.7; Sat, 08 Apr 2023 00:54:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; t=1680940448; 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=fCIy9oWgXj2uukTwz+wLvhTfnk8J7gqXwsBwYiH3dvY=; b=HbVGEVIoT0T84EpkWcmPKFN5zBz27O5/uACQftnKKGrdkvQPOxzhd3RooheEEuAv+4 XD9GCXT1LRa30jFL8xKBClRizjfsolMSAhB0ymtS/CRvx4ZRGjocS4rfTOPhD066pfMB Ik9qyZKBetG3xu5t8GceFwonWtpxjfrpaZdHA4LuJy/v/osTGKi216iw+ZZu/nJ/kbYv lM5VLYHEkRTGtk1eBLsc9hGBKZdDfagZ3RoUocJ6Bm8rZQcfmxoW3bLOcu+RpA6U6S3M OYg0Vp8pDTLeX6RBJCx4HAfttXC/4J/IGTQZMDrPfCk540tgfm3XoAPqwCS1i4EXzDBD rx4Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1680940448; 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=fCIy9oWgXj2uukTwz+wLvhTfnk8J7gqXwsBwYiH3dvY=; b=ZobwMu9lMyUSqgVyWSP2VrzoQy0a3dcc250WhI4bA64sDHfAXSfug6Ww+QGt95zRiJ RYNoAj36xRekM3zVXK8HAZZKfvI8HUKsiVsY5rgDufgrQTTNsUP3iG6LJJRWivXRrP2O Cp06vAEe9E6YBG66XzRaxEyuNy1tJ1xlLXsrM9dc1OTGwLtpIS1CjFMEpYmghrfqWqDO nL8U2aLhxa0f07u+5Ui8tCuI04LL+Z9gjZwBJixYvfLhCGT/NPj8miQaqLUAvOWoCr9v CEyhLU2CjCG/+9elmaxUqQS6bWjJbvw+g4ds7IDa3I20xdT3djG5IO7GDsiv7a1Nf2Lv HYmw== X-Gm-Message-State: AAQBX9dKJRukywZObT6VlARYvX2G3g7dDE9YyL/IDB6b8KwGY6MVloHH ot1Cg2rf3h52ghkNIV0XfkcPVQn+rMKSCg== X-Google-Smtp-Source: AKy350YwJ4UvILK8KrsNZUVN/ZPTCKS/KeafjPkwBu6tSOf7kjMqwLy/Bpq1kZKtNdtT1ak9EOIXSw== X-Received: by 2002:a4a:9613:0:b0:541:5644:3154 with SMTP id q19-20020a4a9613000000b0054156443154mr2029901ooi.8.1680940447914; Sat, 08 Apr 2023 00:54:07 -0700 (PDT) Received: from wedsonaf-dev.home.lan ([189.124.190.154]) by smtp.googlemail.com with ESMTPSA id o6-20020a4a9586000000b0051ffe0fe11bsm2435175ooi.6.2023.04.08.00.54.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 08 Apr 2023 00:54:07 -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 Subject: [PATCH v3 05/13] rust: lock: introduce `SpinLock` Date: Sat, 8 Apr 2023 04:53:32 -0300 Message-Id: <20230408075340.25237-5-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 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 v2 -> v3: 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 693f0b7f4e4f..c997ff7e951e 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 86669f771ee0..df43dff5af5c 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) } + } +} -- 2.34.1