From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 E2C605234 for ; Fri, 2 Aug 2024 00:15:36 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722557738; cv=none; b=P00TmXdpDok/m+rB10Lag8qVqsnEGrL2dG4LpJUMXvZ8OAnER9Rga5FPvG9/VsuTJxcJmdsfLZ/TzsYEJXZIMDxuphm+NuzmoJQTftzdoDnUjBcGr0QyDnHFkLOGJGX5/g16hfKZD68cjsVTByPkwXSYJnUVVwjBHjDNeHqsDxw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722557738; c=relaxed/simple; bh=ATaEraufn9NuoIBXG7cwNDQS7ZyNv5F9ORbQZ90V1+Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jr7l3oZGt9QU5ijb6WljimduZByEGAJ7NxURdVckPzGhxE5bP4MK6ypLgcmW0Yk4ihWUzo8//wC+QMHIEEzRRnSh8KONLxrjFcN13zG8LeV55WP8RPrcU3CdDqUOtP5iBMfDbeKv+msDigvO13/UkZInlthPQXiKaVeY4ixOhlY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=BTUxRq47; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BTUxRq47" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1722557735; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=WgXcZoSROwgBo7MuW9jRTAol2zy4WW/4zI71Tchl2TQ=; b=BTUxRq47xkyla06KJ+ph60IViQUnvaDqo3w6hfNDK0PKBty6dI/AksfE01dNPy9DUkxNQk zh9OVLkEHgMG4JNTXuHehLKO2ubwv8qp3GOYbs06tpFSstn3AqAB7rgQZ6LtGiVvOYXIQJ xpWoYWx3PM0WgDEUc615bHA3KShPSQw= Received: from mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-86-pDmwiqQDNwq1zBENVNFevA-1; Thu, 01 Aug 2024 20:15:31 -0400 X-MC-Unique: pDmwiqQDNwq1zBENVNFevA-1 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 89C2E1955D48; Fri, 2 Aug 2024 00:15:29 +0000 (UTC) Received: from emerald.lyude.net (unknown [10.22.9.60]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id A7A501955D42; Fri, 2 Aug 2024 00:15:25 +0000 (UTC) From: Lyude Paul To: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Danilo Krummrich , airlied@redhat.com, Ingo Molnar , Will Deacon , Waiman Long , Peter Zijlstra , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Martin Rodriguez Reboredo , Trevor Gross , Valentin Obst Subject: [PATCH v3 3/3] rust: sync: Add SpinLockIrq Date: Thu, 1 Aug 2024 20:10:02 -0400 Message-ID: <20240802001452.464985-4-lyude@redhat.com> In-Reply-To: <20240802001452.464985-1-lyude@redhat.com> References: <20240802001452.464985-1-lyude@redhat.com> 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 X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 A variant of SpinLock that is expected to be used in noirq contexts, and thus requires that the user provide an kernel::irq::IrqDisabled to prove they are in such a context upon lock acquisition. This is the rust equivalent of spin_lock_irqsave()/spin_lock_irqrestore(). Signed-off-by: Lyude Paul --- V2: * s/IrqSpinLock/SpinLockIrq/ * Implement `lock::Backend` now that we have `Context` * Add missing periods * Make sure rustdoc examples compile correctly * Add documentation suggestions --- rust/kernel/sync.rs | 2 +- rust/kernel/sync/lock/spinlock.rs | 104 ++++++++++++++++++++++++++++++ 2 files changed, 105 insertions(+), 1 deletion(-) diff --git a/rust/kernel/sync.rs b/rust/kernel/sync.rs index 0ab20975a3b5d..b028ee325f2a6 100644 --- a/rust/kernel/sync.rs +++ b/rust/kernel/sync.rs @@ -15,7 +15,7 @@ pub use arc::{Arc, ArcBorrow, UniqueArc}; pub use condvar::{new_condvar, CondVar, CondVarTimeoutResult}; pub use lock::mutex::{new_mutex, Mutex}; -pub use lock::spinlock::{new_spinlock, SpinLock}; +pub use lock::spinlock::{new_spinlock, new_spinlock_irq, SpinLock, SpinLockIrq}; pub use locked_by::LockedBy; /// Represents a lockdep class. It's a wrapper around C's `lock_class_key`. diff --git a/rust/kernel/sync/lock/spinlock.rs b/rust/kernel/sync/lock/spinlock.rs index 97d85a5576615..47c71d779062a 100644 --- a/rust/kernel/sync/lock/spinlock.rs +++ b/rust/kernel/sync/lock/spinlock.rs @@ -3,6 +3,7 @@ //! A kernel spinlock. //! //! This module allows Rust code to use the kernel's `spinlock_t`. +use kernel::irq::*; /// Creates a [`SpinLock`] initialiser with the given name and a newly-created lock class. /// @@ -116,3 +117,106 @@ unsafe fn unlock(ptr: *mut Self::State, _guard_state: &Self::GuardState) { unsafe { bindings::spin_unlock(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 spinlock that may be acquired when interrupts are disabled. +/// +/// A version of [`SpinLock`] that can only be used in contexts where interrupts for the local CPU +/// are disabled. It requires that the user acquiring the lock provide proof that interrupts are +/// disabled through [`IrqDisabled`]. +/// +/// For more info, see [`SpinLock`]. +/// +/// # 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. +/// +/// ``` +/// use kernel::{ +/// sync::{new_spinlock_irq, SpinLockIrq}, +/// irq::{with_irqs_disabled, IrqDisabled} +/// }; +/// +/// struct Inner { +/// a: u32, +/// b: u32, +/// } +/// +/// #[pin_data] +/// struct Example { +/// c: u32, +/// #[pin] +/// d: SpinLockIrq, +/// } +/// +/// impl Example { +/// fn new() -> impl PinInit { +/// pin_init!(Self { +/// c: 10, +/// d <- new_spinlock_irq!(Inner { a: 20, b: 30 }), +/// }) +/// } +/// } +/// +/// // Accessing an `Example` from a function that can only be called in no-irq contexts +/// fn noirq_work(e: &Example, irq: IrqDisabled<'_>) { +/// assert_eq!(e.c, 10); +/// assert_eq!(e.d.lock_with(irq).a, 20); +/// } +/// +/// // Allocate a boxed `Example` +/// let e = Box::pin_init(Example::new(), GFP_KERNEL)?; +/// +/// // Accessing an `Example` from a context where IRQs may not be disabled already. +/// let b = with_irqs_disabled(|irq| { +/// noirq_work(&e, irq); +/// e.d.lock_with(irq).b +/// }); +/// assert_eq!(b, 30); +/// # Ok::<(), Error>(()) +/// ``` +pub type SpinLockIrq = super::Lock; + +/// A kernel `spinlock_t` lock backend that is acquired in no-irq contexts. +pub struct SpinLockIrqBackend; + +unsafe impl super::Backend for SpinLockIrqBackend { + type State = bindings::spinlock_t; + type GuardState = (); + type Context<'a> = IrqDisabled<'a>; + + 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 spinlock. + unsafe { bindings::spin_unlock(ptr) } + } +} -- 2.45.2