From nobody Thu Oct 31 02:20:51 2024 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 475BC188584 for ; Mon, 16 Sep 2024 21:31:11 +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=1726522273; cv=none; b=HNzSh5nOGRUSPM0ix2yNG83g0iFmpFnljcBODZzi1gjps2aLd6986hZhVGOUgCdusAn5dwTzjxZGPsBmAAfh8AO+yNoUZjgvZdGoYR+e1dOA58EQBlDb8M/PfK0tIclDGFs0j1ackcW6tlqf2K+wJ4hUgytogI0QWDdWqriPYCM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726522273; c=relaxed/simple; bh=J+Kj5kWHLs8eu489PKMmCyDBzk9cLXe8MqLBnhAzMxY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=B7XbPtYTmxIwIwadD1QcNnWwHe7VzeyDqUK+5iuCUAz0GrdV64j4QZLCbSDmMqf7dHQqjH0DoW3qPM+la0tUf0TjlrFDcFnA2bQ9TeDZ+Z2I+fjVNfXfGMcKPkJbI8ZhGY7Ef37wmuQ3o1Y+3Xx4dZx8ltp7IEaKF0bXSs9FiE8= 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=Nq8HVv43; 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="Nq8HVv43" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1726522270; 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=8oIvdAsWFPJzZrabfZBBzhpeBee144e8PLeqisrxPnQ=; b=Nq8HVv43RBaWeJkSvbfWJeNWf+jZdW9aLgIQjuU0+JU2sIQJYqy1dMgzAztvj/atNxVkux un10OprsTpccay3VHAI+KyoXwFoKayqgXfVprLFB9d0Vo+PcSYbTmAyJyxSZLtomF1jQ4Y NrG2os9tZB8+xOqFkQnMU+XY8IswRFY= Received: from mx-prod-mc-05.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-324-ZueokHCwNm2jw6RfDptEbA-1; Mon, 16 Sep 2024 17:31:05 -0400 X-MC-Unique: ZueokHCwNm2jw6RfDptEbA-1 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id A9AAC1955DCC; Mon, 16 Sep 2024 21:31:02 +0000 (UTC) Received: from chopper.redhat.com (unknown [10.22.33.131]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 8484619560AF; Mon, 16 Sep 2024 21:30:58 +0000 (UTC) From: Lyude Paul To: rust-for-linux@vger.kernel.org Cc: Danilo Krummrich , airlied@redhat.com, Ingo Molnar , Will Deacon , Waiman Long , Peter Zijlstra , Thomas Gleixner , linux-kernel@vger.kernel.org, Benno Lossin , Daniel Almeida , Gary Guo , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Andreas Hindborg , Alice Ryhl , Trevor Gross , Martin Rodriguez Reboredo , Valentin Obst Subject: [PATCH v6 3/3] rust: sync: Add SpinLockIrq Date: Mon, 16 Sep 2024 17:28:06 -0400 Message-ID: <20240916213025.477225-4-lyude@redhat.com> In-Reply-To: <20240916213025.477225-1-lyude@redhat.com> References: <20240916213025.477225-1-lyude@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Content-Type: text/plain; charset="utf-8" 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 Reviewed-by: Benno Lossin Reviewed-by: Daniel Almeida Reviewed-by: Gary Guo Reviewed-by: Boqun Feng Reviewed-by: Trevor Gross --- 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, SpinLoc= kIrq}; pub use locked_by::LockedBy; =20 /// 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/spin= lock.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::*; =20 /// Creates a [`SpinLock`] initialiser with the given name and a newly-cre= ated 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)? $(,)?) =3D> { + $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 inte= rrupts for the local CPU +/// are disabled. It requires that the user acquiring the lock provide pro= of that interrupts are +/// disabled through [`IrqDisabled`]. +/// +/// For more info, see [`SpinLock`]. +/// +/// # Examples +/// +/// The following example shows how to declare, allocate initialise and ac= cess a struct (`Example`) +/// that contains an inner struct (`Inner`) that is protected by a spinloc= k. +/// +/// ``` +/// 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 n= o-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 =3D Box::pin_init(Example::new(), GFP_KERNEL)?; +/// +/// // Accessing an `Example` from a context where IRQs may not be disable= d already. +/// let b =3D with_irqs_disabled(|irq| { +/// noirq_work(&e, irq); +/// e.d.lock_with(irq).b +/// }); +/// assert_eq!(b, 30); +/// # Ok::<(), Error>(()) +/// ``` +pub type SpinLockIrq =3D 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 =3D bindings::spinlock_t; + type GuardState =3D (); + type Context<'a> =3D 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 `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 spinlock. + unsafe { bindings::spin_unlock(ptr) } + } +} --=20 2.46.0