From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 91F5F4756B7 for ; Tue, 4 Aug 2026 16:15:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785860130; cv=none; b=QOa/F/4z5DGzVeHYGrYBTgWkU9Q5a73IzVebvy9QtmvdE4gNe3Wa1anDwi/DaQD/6PW2zVRcaFsiDgd3pp6QakMDJcjykjHRSq4b7nkUn2uO+yrVfUVZtH5EWZ+WaWxAZlXUaKJt88RrfX3f7V49MoGL5Wc2VHHWEVIZz9+2G3A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785860130; c=relaxed/simple; bh=kZU5uFqdjWiRbrVf1fTNRv9ePx+qKQEq8Hc6Bs6H2Cs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=BjAzRv4vba9wjTDyq8HJrzz8pLJeNxn751D9PBUR0ld38hOIjUOG93/0MHtjWtutSPmmRk+CwNNA6STUhD+ySE0dtAo1VS++F8UcCKt51z/l85nTv1CT5BXIDgoqbesZjBc8PeDqId0Q9FFxGbBNUHejpkbZKk2uUxAD0eMuPOg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BWEzvKpr; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BWEzvKpr" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5CC031F00A3F; Tue, 4 Aug 2026 16:15:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785860122; bh=2MYZgIP+osziR2bs888gmmBvgXIfwDVrZfFhcS+axXE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=BWEzvKprIWof6jEJHHyNb4i8vHe/Slyz+CGATfaa2/ueOxjhQuivs47yKwukEnBi5 o5a83COJ15flU+J/pRTw+jC9cDGQ1f+CB8f3O0WJkjjve4RxLaIDREQzZ8iJzjGIyw tcp/VZEnO5cpOSEaAZeUN1WSsuVIyMGRwq4b8LQHeMEtfiSqCBDJ5a0y5SUEEUoFLg lWFbtNLPr38HObFQjQgUXCBi214JQN9ykqtRF1NodLsCXGUHm51lrEQFXtIIiDUPcW BCVMXDdGalNlkm98xr999nl65NrxkFt0r8BO4JFpd3/RewKkDLODkYGg1TDndBWkQE 1RjYLxm7p24Bg== Received: from phl-compute-03.internal (phl-compute-03.internal [10.202.2.43]) by mailfauth.phl.internal (Postfix) with ESMTP id 9AD19F40066; Tue, 4 Aug 2026 12:15:21 -0400 (EDT) Received: from phl-frontend-03 ([10.202.2.162]) by phl-compute-03.internal (MEProxy); Tue, 04 Aug 2026 12:15:21 -0400 X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: dmFkZTGieA2PtfV9jSFchkBSUGRvAWb1NITTGgeikxrU+GWeOukLWTSA/NzmsBjdHwUYbe 0erteAkfc4UaRDf0dMOdxgNSF+x3Zu0BbdfmeM7AKPbfK0OPT0HLroc+sluO/cC9IMMPSf UC/oH0bN/7dDLlq3yKu6wzn2cf4YXKbKDiff65imTlvzFYVAi2jiR3u4/PsSuR9+0G3TT4 iRoMH87H0urJqIjMbAilmNI/FWk0WY51GTR9tXwGcnj+pTvT++vrrx98cMKjuNNccHsv3y mSjasO/eyTPpxx12FEV6IRjl72E/fAhMzSnlHo2hlR954mzd3YIM5xarphE6YabMo8hGcY oMCHhIEUbq4hK8080vy7dQkB1j0jHmE0hq1BwRdoXk3RLMqAcOFs5PsgB1ALvDUw+HJB5r uljmvzYM9jrhHULSya9H4yoYhTC/m/AKFxlOrGsF75H6KAYOlMNeBygl2hVkHd8rflL/19 RzJ8SpgRGesVWVf57MJDth0r0nlU89BCC0lmI0GShYRWqof3L2F0YK2e0F1BRv6WtiEvbD EkDHaWcYtxzZmCZ16PnAoCA7tVNjay+5brMnQEdzHYy/p1JIof4gdd+TxQ5s4kj8T3xqs4 XmWO2J8oye8LTSVV8RZXYim9vk3cY1Z7Hux0ZEul1KjIuuLT7nuPCjgk+p8Q X-ME-Proxy: Feedback-ID: i8dbe485b:Fastmail Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 4 Aug 2026 12:15:20 -0400 (EDT) From: Boqun Feng To: Peter Zijlstra Cc: "Ingo Molnar" , "Will Deacon" , "Boqun Feng" , "Waiman Long" , "Gary Guo" , "Alice Ryhl" , "Lyude Paul" , "Daniel Almeida" , =?UTF-8?q?Onur=20=C3=96zkan?= , "Miguel Ojeda" , "Danilo Krummrich" , linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org Subject: [PATCH v4 16/17] rust: sync: Add SpinLockIrq Date: Tue, 4 Aug 2026 09:14:38 -0700 Message-ID: <20260804161447.84806-17-boqun@kernel.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260804161447.84806-1-boqun@kernel.org> References: <20260804161447.84806-1-boqun@kernel.org> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Lyude Paul A variant of `SpinLock` that ensures interrupts are disabled in the critical section. `lock()` will ensure that either interrupts are already disabled or disable them. `unlock()` will reverse the respective operation. [Boqun: Port to use spin_lock_irq_disable() and spin_unlock_irq_enable()] Signed-off-by: Lyude Paul Reviewed-by: Gary Guo Signed-off-by: Boqun Feng --- rust/kernel/sync.rs | 9 +- rust/kernel/sync/lock/global.rs | 3 + rust/kernel/sync/lock/spinlock.rs | 230 ++++++++++++++++++++++++++++++ 3 files changed, 241 insertions(+), 1 deletion(-) diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs index 993dbf2caa0e..df4f2604ff9b 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -27,7 +27,14 @@ pub use condvar::{new_condvar, CondVar, CondVarTimeoutResult}; pub use lock::global::{global_lock, GlobalGuard, GlobalLock, GlobalLockBackend, GlobalLockedBy}; pub use lock::mutex::{new_mutex, Mutex, MutexGuard}; -pub use lock::spinlock::{new_spinlock, SpinLock, SpinLockGuard}; +pub use lock::spinlock::{ + new_spinlock, + new_spinlock_irq, + SpinLock, + SpinLockGuard, + SpinLockIrq, + SpinLockIrqGuard, // +}; pub use locked_by::LockedBy; pub use refcount::Refcount; pub use set_once::SetOnce; diff --git a/rust/kernel/sync/lock/global.rs b/rust/kernel/sync/lock/global.rs index ec2dd84316fc..ebb10521d8bd 100644 --- a/rust/kernel/sync/lock/global.rs +++ b/rust/kernel/sync/lock/global.rs @@ -306,4 +306,7 @@ macro_rules! global_lock_inner { (backend SpinLock) => { $crate::sync::lock::spinlock::SpinLockBackend }; + (backend SpinLockIrq) => { + $crate::sync::lock::spinlock::SpinLockIrqBackend + }; } diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs index d75af32218ba..872544948e5d 100644 --- a/rust/kernel/sync/lock/spinlock.rs +++ b/rust/kernel/sync/lock/spinlock.rs @@ -4,6 +4,7 @@ //! //! This module allows Rust code to use the kernel's `spinlock_t`. use super::*; +use crate::prelude::*; /// Creates a [`SpinLock`] initialiser with the given name and a newly-created lock class. /// @@ -143,3 +144,232 @@ unsafe fn assert_is_held(ptr: *mut Self::State) { unsafe { bindings::spin_assert_is_held(ptr) } } } + +/// Creates a [`SpinLockIrq`] initialiser with the given name and a newly-created lock class. +/// +/// It uses the name if one is given, otherwise it generates one based on the file name and line +/// number. +#[macro_export] +macro_rules! new_spinlock_irq { + ($inner:expr $(, $name:literal)? $(,)?) => { + $crate::sync::SpinLockIrq::new( + $inner, $crate::optional_name!($($name)?), $crate::static_lock_class!()) + }; +} +pub use new_spinlock_irq; + +/// A variant of `SpinLock` that ensures interrupts are disabled in the critical section. +/// +/// For more info on spinlocks, see [`SpinLock`]. For more information on interrupts, +/// [see the interrupt module](kernel::interrupt). +/// +/// # Examples +/// +/// The following example shows how to declare, allocate initialise and access a struct (`Example`) +/// that contains an inner struct (`Inner`) that is protected by a spinlock that requires local +/// processor interrupts to be disabled. +/// +/// ``` +/// use kernel::sync::{new_spinlock_irq, SpinLockIrq}; +/// +/// struct Inner { +/// a: u32, +/// b: u32, +/// } +/// +/// #[pin_data] +/// struct Example { +/// #[pin] +/// c: SpinLockIrq, +/// #[pin] +/// d: SpinLockIrq, +/// } +/// +/// impl Example { +/// fn new() -> impl PinInit { +/// pin_init!(Self { +/// c <- new_spinlock_irq!(Inner { a: 0, b: 10 }), +/// d <- new_spinlock_irq!(Inner { a: 20, b: 30 }), +/// }) +/// } +/// } +/// +/// // Allocate a boxed `Example` +/// let e = KBox::pin_init(Example::new(), GFP_KERNEL)?; +/// +/// // Accessing an `Example` from a context where interrupts may not be disabled already. +/// let c_guard = e.c.lock(); // interrupts are disabled now, +1 interrupt disable refcount +/// let d_guard = e.d.lock(); // no interrupt state change, +1 interrupt disable refcount +/// +/// assert_eq!(c_guard.a, 0); +/// assert_eq!(c_guard.b, 10); +/// assert_eq!(d_guard.a, 20); +/// assert_eq!(d_guard.b, 30); +/// +/// drop(c_guard); // Dropping c_guard will not re-enable interrupts just yet, since d_guard is +/// // still in scope. +/// drop(d_guard); // Last interrupt disable reference dropped here, so interrupts are re-enabled +/// // now +/// # Ok::<(), Error>(()) +/// ``` +/// +/// [`lock()`]: SpinLockIrq::lock +pub type SpinLockIrq = super::Lock; + +/// A kernel `spinlock_t` lock backend that can only be acquired in interrupt disabled contexts. +pub struct SpinLockIrqBackend; + +/// A [`Guard`] acquired from locking a [`SpinLockIrq`] using [`lock()`]. +/// +/// This is simply a type alias for a [`Guard`] returned from locking a [`SpinLockIrq`] using +/// [`lock()`]. It will unlock the [`SpinLockIrq`] and decrement the local processor's interrupt +/// disablement refcount upon being dropped. +/// +/// [`lock()`]: SpinLockIrq::lock +pub type SpinLockIrqGuard<'a, T> = Guard<'a, T, SpinLockIrqBackend>; + +// SAFETY: The underlying kernel `spinlock_t` object ensures mutual exclusion. `relock` uses the +// default implementation that always calls the same locking method. +unsafe impl Backend for SpinLockIrqBackend { + type State = bindings::spinlock_t; + type GuardState = (); + + #[inline] + unsafe fn init( + ptr: *mut Self::State, + name: *const crate::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) } + } + + #[inline] + 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_irq_disable(ptr) } + } + + #[inline] + 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 spinlock. + unsafe { bindings::spin_unlock_irq_enable(ptr) } + } + + #[inline] + unsafe fn try_lock(ptr: *mut Self::State) -> Option { + // SAFETY: The `ptr` pointer is guaranteed to be valid and initialized before use. + let result = unsafe { bindings::spin_trylock_irq_disable(ptr) }; + + if result != 0 { + Some(()) + } else { + None + } + } + + #[inline] + unsafe fn assert_is_held(ptr: *mut Self::State) { + // SAFETY: The `ptr` pointer is guaranteed to be valid and initialized before use. + unsafe { bindings::spin_assert_is_held(ptr) } + } +} + +#[kunit_tests(rust_spinlock_irq_condvar)] +mod tests { + use super::*; + use crate::{ + sync::*, + workqueue::{ + self, + impl_has_work, + new_work, + Work, + WorkItem, // + }, + }; + + struct TestState { + value: u32, + waiter_ready: bool, + } + + #[pin_data] + struct Test { + #[pin] + state: SpinLockIrq, + + #[pin] + state_changed: CondVar, + + #[pin] + waiter_state_changed: CondVar, + + #[pin] + wait_work: Work, + } + + impl_has_work! { + impl HasWork for Test { self.wait_work } + } + + impl Test { + pub(crate) fn new() -> Result> { + Arc::try_pin_init( + try_pin_init!( + Self { + state <- new_spinlock_irq!(TestState { + value: 1, + waiter_ready: false + }), + state_changed <- new_condvar!(), + waiter_state_changed <- new_condvar!(), + wait_work <- new_work!("IrqCondvarTest::wait_work") + } + ), + GFP_KERNEL, + ) + } + } + + impl WorkItem for Test { + type Pointer = Arc; + + fn run(this: Arc) { + // Wait for the test to be ready to wait for us + let mut state = this.state.lock(); + + // Make sure the interrupts actually turned off + // SAFETY: It's always safe to call `lockdep_assert_irqs_disabled()` + unsafe { bindings::lockdep_assert_irqs_disabled() }; + + while !state.waiter_ready { + this.waiter_state_changed.wait(&mut state); + } + + // Deliver the exciting value update our test has been waiting for + state.value += 1; + this.state_changed.notify_sync(); + } + } + + #[test] + fn spinlock_irq_condvar() -> Result { + let testdata = Test::new()?; + + let _ = workqueue::system().enqueue(testdata.clone()); + + // Let the updater know when we're ready to wait + let mut state = testdata.state.lock(); + state.waiter_ready = true; + testdata.waiter_state_changed.notify_sync(); + + // Wait for the exciting value update + testdata.state_changed.wait(&mut state); + assert_eq!(state.value, 2); + Ok(()) + } +} -- 2.50.1 (Apple Git-155)