From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) (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 BE12224E019; Tue, 15 Jul 2025 15:17:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=148.251.105.195 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752592632; cv=none; b=G+PjovYtnDwx/ZWTuSASVOxZi7hhiixF/Z1s0KV+guaXMfj1K8EJ0HWJFmxhuKYvtPkecRXMJ515iZMiw1UlgND14tLniywicrs40oCgs0IZbcnTQypA6AUU2MUQvCoCE7VL0jXgoXCgz0XiMRwv0Jr2bU1HkIGmXGdOhYRZamg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752592632; c=relaxed/simple; bh=GaqTGAvm/SZ/WWXgNLPIL8I1p20P80a2MfUJbHC9h3k=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=BNX5mY1rGPjstrr0kD7mZ9zUi3E2CRtpGYZ+OB+KAI2XQM4ZE8aiCfAExRSqO2VECaNNYXFpnwq9IiMevX8y6cV4EODRZmPdepcHKGa7iPuvlSl/uSauEHQsRw3AiBY1rBUJ3rmLKV0jUxDtOXcNrdLIFP5hoSz2384vJ7TcZEk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com; spf=pass smtp.mailfrom=collabora.com; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b=ZqyKb15J; arc=none smtp.client-ip=148.251.105.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=collabora.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=collabora.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=collabora.com header.i=@collabora.com header.b="ZqyKb15J" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1752592629; bh=GaqTGAvm/SZ/WWXgNLPIL8I1p20P80a2MfUJbHC9h3k=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=ZqyKb15JfttsACE4yi6CDpPWljpdwgd4XnV/UnUFWiAqScpDByQHg0ZGvImkI0uUS jmcPYnzXqYg/y9Gn8ZEy0wQCB+X8K3PLNO8w2zM4qX57qzpgoMK0QJDZZUSc/Ej8YI nIXifLOnpUGOnp2yBeIa4hqXvXLkHKf8+sl0pbe4OzmLqbQh37uktloSh5EdeWOgY6 TB3m+4E6ZPHNZmsivu7x4WDEozf/I2tMmuGG8Hnt1fItvlDXKlWMJj0CtCr9FqYoXn NUKUFWgm0X8B1gypZd7TebG4AAtEizPCiw3TJbgv8cmXAckxzEQfNwJLOiyJs0cp9+ 4SSVvxpiIDV2g== Received: from [192.168.0.2] (unknown [IPv6:2804:14d:72b4:82f6:67c:16ff:fe57:b5a3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dwlsalmeida) by bali.collaboradmins.com (Postfix) with ESMTPSA id 40DCF17E1293; Tue, 15 Jul 2025 17:17:06 +0200 (CEST) From: Daniel Almeida Date: Tue, 15 Jul 2025 12:16:41 -0300 Subject: [PATCH v7 4/6] rust: irq: add support for threaded IRQs and handlers Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20250715-topics-tyr-request_irq2-v7-4-d469c0f37c07@collabora.com> References: <20250715-topics-tyr-request_irq2-v7-0-d469c0f37c07@collabora.com> In-Reply-To: <20250715-topics-tyr-request_irq2-v7-0-d469c0f37c07@collabora.com> To: Miguel Ojeda , Alex Gaynor , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Greg Kroah-Hartman , "Rafael J. Wysocki" , Thomas Gleixner , Bjorn Helgaas , =?utf-8?q?Krzysztof_Wilczy=C5=84ski?= , Benno Lossin Cc: linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-pci@vger.kernel.org, Daniel Almeida X-Mailer: b4 0.14.2 This patch adds support for threaded IRQs and handlers through irq::ThreadedRegistration and the irq::ThreadedHandler trait. Threaded interrupts are more permissive in the sense that further processing is possible in a kthread. This means that said execution takes place outside of interrupt context, which is rather restrictive in many ways. Registering a threaded irq is dependent upon having an IrqRequest that was previously allocated by a given device. This will be introduced in subsequent patches. Signed-off-by: Daniel Almeida --- rust/kernel/irq.rs | 5 +- rust/kernel/irq/request.rs | 227 ++++++++++++++++++++++++++++++++++++++++++++- 2 files changed, 229 insertions(+), 3 deletions(-) diff --git a/rust/kernel/irq.rs b/rust/kernel/irq.rs index 01bd08884b72c2a3a9460897bce751c732a19794..aaa40001bafca617c588c799bb41144921595cae 100644 --- a/rust/kernel/irq.rs +++ b/rust/kernel/irq.rs @@ -16,4 +16,7 @@ /// IRQ allocation and handling. pub mod request; -pub use request::{Handler, IrqRequest, IrqReturn, Registration}; +pub use request::{ + Handler, IrqRequest, IrqReturn, Registration, ThreadedHandler, ThreadedIrqReturn, + ThreadedRegistration, +}; diff --git a/rust/kernel/irq/request.rs b/rust/kernel/irq/request.rs index 2f4637d8bc4c9fda23cbc8307687035957b0042a..aa1b957fa18f927df2f14b18076393e1be2cf1d6 100644 --- a/rust/kernel/irq/request.rs +++ b/rust/kernel/irq/request.rs @@ -1,8 +1,9 @@ // SPDX-License-Identifier: GPL-2.0 // SPDX-FileCopyrightText: Copyright 2025 Collabora ltd. -//! This module provides types like [`Registration`] which allow users to -//! register handlers for a given IRQ line. +//! This module provides types like [`Registration`] and +//! [`ThreadedRegistration`], which allow users to register handlers for a given +//! IRQ line. use core::marker::PhantomPinned; @@ -265,3 +266,225 @@ pub fn synchronize(&self, dev: &Device) -> Result { let handler = unsafe { &*(ptr as *const T) }; T::handle(handler) as c_uint } + +/// The value that can be returned from `ThreadedHandler::handle_irq`. +#[repr(u32)] +pub enum ThreadedIrqReturn { + /// The interrupt was not from this device or was not handled. + None = bindings::irqreturn_IRQ_NONE, + + /// The interrupt was handled by this device. + Handled = bindings::irqreturn_IRQ_HANDLED, + + /// The handler wants the handler thread to wake up. + WakeThread = bindings::irqreturn_IRQ_WAKE_THREAD, +} + +/// Callbacks for a threaded IRQ handler. +pub trait ThreadedHandler: Sync { + /// The hard IRQ handler. + /// + /// This is executed in interrupt context, hence all corresponding + /// limitations do apply. All work that does not necessarily need to be + /// executed from interrupt context, should be deferred to the threaded + /// handler, i.e. [`ThreadedHandler::handle_threaded`]. + fn handle(&self) -> ThreadedIrqReturn; + + /// The threaded IRQ handler. + /// + /// This is executed in process context. The kernel creates a dedicated + /// kthread for this purpose. + fn handle_threaded(&self) -> IrqReturn; +} + +impl ThreadedHandler for Arc { + fn handle(&self) -> ThreadedIrqReturn { + T::handle(self) + } + + fn handle_threaded(&self) -> IrqReturn { + T::handle_threaded(self) + } +} + +impl ThreadedHandler for Box { + fn handle(&self) -> ThreadedIrqReturn { + T::handle(self) + } + + fn handle_threaded(&self) -> IrqReturn { + T::handle_threaded(self) + } +} + +/// A registration of a threaded IRQ handler for a given IRQ line. +/// +/// Two callbacks are required: one to handle the IRQ, and one to handle any +/// other work in a separate thread. +/// +/// The thread handler is only called if the IRQ handler returns `WakeThread`. +/// +/// # Examples +/// +/// The following is an example of using `ThreadedRegistration`. It uses a +/// [`AtomicU32`](core::sync::AtomicU32) to provide the interior mutability. +/// +/// ``` +/// use core::sync::atomic::AtomicU32; +/// use core::sync::atomic::Ordering; +/// +/// use kernel::prelude::*; +/// use kernel::device::Bound; +/// use kernel::irq::flags; +/// use kernel::irq::ThreadedIrqReturn; +/// use kernel::irq::ThreadedRegistration; +/// use kernel::irq::IrqRequest; +/// use kernel::irq::IrqReturn; +/// use kernel::sync::Arc; +/// use kernel::c_str; +/// use kernel::alloc::flags::GFP_KERNEL; +/// +/// // Declare a struct that will be passed in when the interrupt fires. The u32 +/// // merely serves as an example of some internal data. +/// struct Data(AtomicU32); +/// +/// // [`kernel::irq::request::ThreadedHandler::handle`] takes `&self`. This example +/// // illustrates how interior mutability can be used when sharing the data +/// // between process context and IRQ context. +/// type Handler = Data; +/// +/// impl kernel::irq::request::ThreadedHandler for Handler { +/// // This is executing in IRQ context in some CPU. Other CPUs can still +/// // try to access the data. +/// fn handle(&self) -> ThreadedIrqReturn { +/// self.0.fetch_add(1, Ordering::Relaxed); +/// // By returning `WakeThread`, we indicate to the system that the +/// // thread function should be called. Otherwise, return +/// // ThreadedIrqReturn::Handled. +/// ThreadedIrqReturn::WakeThread +/// } +/// +/// // This will run (in a separate kthread) if and only if `handle` +/// // returns `WakeThread`. +/// fn handle_threaded(&self) -> IrqReturn { +/// self.0.fetch_add(1, Ordering::Relaxed); +/// IrqReturn::Handled +/// } +/// } +/// +/// // Registers a threaded IRQ handler for the given IrqRequest. +/// // +/// // This is executing in process context and assumes that `request` was +/// // previously acquired from a device. +/// fn register_threaded_irq(handler: Handler, request: IrqRequest<'_>) -> Result>> { +/// let registration = ThreadedRegistration::new(request, flags::SHARED, c_str!("my_device"), handler); +/// +/// let registration = Arc::pin_init(registration, GFP_KERNEL)?; +/// +/// // The data can be accessed from process context too. +/// registration.handler().0.fetch_add(1, Ordering::Relaxed); +/// +/// Ok(registration) +/// } +/// # Ok::<(), Error>(()) +/// ``` +/// +/// # Invariants +/// +/// * We own an irq handler using `&T` as its private data. +/// +#[pin_data] +pub struct ThreadedRegistration { + #[pin] + inner: Devres, + + #[pin] + handler: T, + + /// Pinned because we need address stability so that we can pass a pointer + /// to the callback. + #[pin] + _pin: PhantomPinned, +} + +impl ThreadedRegistration { + /// Registers the IRQ handler with the system for the given IRQ number. + pub fn new<'a>( + request: IrqRequest<'a>, + flags: Flags, + name: &'static CStr, + handler: T, + ) -> impl PinInit + 'a { + try_pin_init!(&this in Self { + handler, + inner <- Devres::new( + request.dev, + try_pin_init!(RegistrationInner { + // SAFETY: `this` is a valid pointer to the `ThreadedRegistration` instance. + cookie: unsafe { &raw mut (*this.as_ptr()).handler }.cast(), + irq: { + // SAFETY: + // - The callbacks are valid for use with request_threaded_irq. + // - If this succeeds, the slot is guaranteed to be valid until the + // destructor of Self runs, which will deregister the callbacks + // before the memory location becomes invalid. + to_result(unsafe { + bindings::request_threaded_irq( + request.irq, + Some(handle_threaded_irq_callback::), + Some(thread_fn_callback::), + flags.into_inner() as usize, + name.as_char_ptr(), + (&raw mut (*this.as_ptr()).handler).cast(), + ) + })?; + request.irq + } + }) + ), + _pin: PhantomPinned, + }) + } + + /// Returns a reference to the handler that was registered with the system. + pub fn handler(&self) -> &T { + &self.handler + } + + /// Wait for pending IRQ handlers on other CPUs. + /// + /// This will attempt to access the inner [`Devres`] container. + pub fn try_synchronize(&self) -> Result { + let inner = self.inner.try_access().ok_or(ENODEV)?; + inner.synchronize(); + Ok(()) + } + + /// Wait for pending IRQ handlers on other CPUs. + pub fn synchronize(&self, dev: &Device) -> Result { + let inner = self.inner.access(dev)?; + inner.synchronize(); + Ok(()) + } +} + +/// # Safety +/// +/// This function should be only used as the callback in `request_threaded_irq`. +unsafe extern "C" fn handle_threaded_irq_callback( + _irq: i32, + ptr: *mut c_void, +) -> c_uint { + // SAFETY: `ptr` is a pointer to T set in `ThreadedRegistration::new` + let handler = unsafe { &*(ptr as *const T) }; + T::handle(handler) as c_uint +} + +/// # Safety +/// +/// This function should be only used as the callback in `request_threaded_irq`. +unsafe extern "C" fn thread_fn_callback(_irq: i32, ptr: *mut c_void) -> c_uint { + // SAFETY: `ptr` is a pointer to T set in `ThreadedRegistration::new` + let handler = unsafe { &*(ptr as *const T) }; + T::handle_threaded(handler) as c_uint +} -- 2.50.0