From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 91E3E1F76C0; Tue, 17 Dec 2024 15:56:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734451017; cv=none; b=JeWB0wfHx1JNaYCoDk4b93HAfv+v2GiysF5uPjP49GOtcN/K5SjWK0K95JcMTjlF/o9QGc2wbl8PKbl0C5ON6L5rOIdtyAvPykZpgdVtEGmDQ0dRNHBhMTjEM15JvM1HPQS9fKhYziCxXI8znoeIB6X3/vq2D38rFmR0hAcAUyE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734451017; c=relaxed/simple; bh=XA1cD9dyHs4PM1ZV8ZO3BjAUlvYxEt2jsMm2z6jdQDk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Rvpz8E3dGau/E5zcCi+S3S8Nd/4Flf9wH0pIhcFtS1ldkkzKRpimUen42lEYjS95AvpYuLM1HCurr0Uaglj9lQeiaIkb2wAx6uhNTzqA7/24JFWHlctQJdjBJewBvF+RS6jRhg8Ea/SGAlIkuYb3IbVZUFkCFOosAXOlZ0FKNLY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=MM1YEsyn; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="MM1YEsyn" Received: by smtp.kernel.org (Postfix) with ESMTPSA id DA00AC4CED3; Tue, 17 Dec 2024 15:56:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1734451017; bh=XA1cD9dyHs4PM1ZV8ZO3BjAUlvYxEt2jsMm2z6jdQDk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MM1YEsynpd3Ipr0yJCLluQiT0Axt5AyQBFYWTvVMqtEY3mfAN3Iffwa1IKB2egOZR j4eCxDLMUbrVJrOmIjX5fVIwiNc6k4cklolqs+/brvN9nrFwImA5xMv9RneKKiYTOu 8K+NUAmT9KmcsxYARcGi6RnXewMk9pYzlY1g3BSj6wypAaFTA84wZoz+yrsXt/9vVR E4MjSpBytErdLIgVM5494g7ThLNmsPEn2/Q7WNHgWvyHvaoGDu71pTpTIS8pyGL/4W zBrbLP54ayAagGkxcoxIzUMNScywX5a++PikjRnnkYvrzH4JjU+tuGO970YKW9sL+A aQsyHRsH+3EYw== Date: Tue, 17 Dec 2024 16:56:54 +0100 From: Frederic Weisbecker To: Andreas Hindborg Cc: Miguel Ojeda , Anna-Maria Behnsen , Thomas Gleixner , Danilo Krummrich , Alex Gaynor , Boqun Feng , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Alice Ryhl , Trevor Gross , Lyude Paul , Guangbo Cui <2407018371@qq.com>, Dirk Behme , Daniel Almeida , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v5 02/14] rust: hrtimer: introduce hrtimer support Message-ID: References: <20241217-hrtimer-v3-v6-12-rc2-v5-0-b34c20ac2cb7@kernel.org> <20241217-hrtimer-v3-v6-12-rc2-v5-2-b34c20ac2cb7@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20241217-hrtimer-v3-v6-12-rc2-v5-2-b34c20ac2cb7@kernel.org> Le Tue, Dec 17, 2024 at 04:17:33PM +0100, Andreas Hindborg a écrit : > This patch adds support for intrusive use of the hrtimer system. For now, > only one timer can be embedded in a Rust struct. > > The hrtimer Rust API is based on the intrusive style pattern introduced by > the Rust workqueue API. > > Signed-off-by: Andreas Hindborg > --- > rust/kernel/time.rs | 2 + > rust/kernel/time/hrtimer.rs | 296 ++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 298 insertions(+) > > diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs > index f59e0fea79d3acfddd922f601f569353609aeec1..51c3532eee0184495ed5b7d717860c9980ff2a43 100644 > --- a/rust/kernel/time.rs > +++ b/rust/kernel/time.rs > @@ -10,6 +10,8 @@ > > use core::convert::Into; > > +pub mod hrtimer; > + > /// The number of nanoseconds per millisecond. > pub const NSEC_PER_MSEC: i64 = bindings::NSEC_PER_MSEC as i64; > > diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs > new file mode 100644 > index 0000000000000000000000000000000000000000..b09bdb8bc2037bf116a9a87b16271f4045f53aa9 > --- /dev/null > +++ b/rust/kernel/time/hrtimer.rs > @@ -0,0 +1,296 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +//! Intrusive high resolution timers. > +//! > +//! Allows running timer callbacks without doing allocations at the time of > +//! starting the timer. For now, only one timer per type is allowed. > +//! > +//! # Vocabulary > +//! > +//! A timer is initialized in the **stopped** state. A stopped timer can be > +//! **started** with an **expiry** time. After the timer is started, it is > +//! **running**. When the timer **expires**, the timer handler is executed. > +//! After the handler has executed, the timer may be **restarted** or > +//! **stopped**. A running timer can be **cancelled** before it's handler is > +//! executed. A timer that is cancelled enters the **stopped** state. > +//! > +//! States: > +//! > +//! * Stopped > +//! * Running > +//! > +//! Operations: > +//! > +//! * Start > +//! * Cancel > +//! * Stop > +//! * Restart > +//! > +//! Events: > +//! > +//! * Expire > + > +use crate::{init::PinInit, prelude::*, time::Ktime, types::Opaque}; > +use core::marker::PhantomData; > + > +/// A timer backed by a C `struct hrtimer`. > +/// > +/// # Invariants > +/// > +/// * `self.timer` is initialized by `bindings::hrtimer_setup`. > +#[pin_data] > +#[repr(C)] > +pub struct Timer { I seem to remember we had a debate on that. Why not call that Hrtimer? Timer is a bit too generic for a name. I suspect you'll need to introduce jiffies based timer bindings in the future as well and then some confusion may arise. > + #[pin] > + timer: Opaque, > + _t: PhantomData, > +} > + > +// SAFETY: A `Timer` can be moved to other threads and used/dropped from there. > +unsafe impl Send for Timer {} > + > +// SAFETY: Timer operations are locked on C side, so it is safe to operate on a > +// timer from multiple threads > +unsafe impl Sync for Timer {} > + > +impl Timer { > + /// Return an initializer for a new timer instance. > + pub fn new() -> impl PinInit > + where > + T: TimerCallback, > + { > + pin_init!(Self { > + // INVARIANTS: We initialize `timer` with `hrtimer_setup` below. > + timer <- Opaque::ffi_init(move |place: *mut bindings::hrtimer| { > + // SAFETY: By design of `pin_init!`, `place` is a pointer live > + // allocation. hrtimer_setup will initialize `place` and does > + // not require `place` to be initialized prior to the call. > + unsafe { > + bindings::hrtimer_setup( > + place, > + Some(T::CallbackTarget::run), > + bindings::CLOCK_MONOTONIC as i32, > + bindings::hrtimer_mode_HRTIMER_MODE_REL, Always relative? > + ); > + } > + }), > + _t: PhantomData, > + }) > + } > + > + /// Get a pointer to the contained `bindings::hrtimer`. > + /// > + /// # Safety > + /// > + /// `ptr` must point to a live allocation of at least the size of `Self`. > + unsafe fn raw_get(ptr: *const Self) -> *mut bindings::hrtimer { > + // SAFETY: The field projection to `timer` does not go out of bounds, > + // because the caller of this function promises that `ptr` points to an > + // allocation of at least the size of `Self`. > + unsafe { Opaque::raw_get(core::ptr::addr_of!((*ptr).timer)) } > + } > + > + /// Cancel an initialized and potentially running timer. > + /// > + /// If the timer handler is running, this will block until the handler is > + /// finished. > + /// > + /// # Safety > + /// > + /// `self_ptr` must point to a valid `Self`. > + #[allow(dead_code)] > + pub(crate) unsafe fn raw_cancel(self_ptr: *const Self) -> bool { > + // SAFETY: timer_ptr points to an allocation of at least `Timer` size. > + let c_timer_ptr = unsafe { Timer::raw_get(self_ptr) }; > + > + // If handler is running, this will wait for handler to finish before > + // returning. > + // SAFETY: `c_timer_ptr` is initialized and valid. Synchronization is > + // handled on C side. > + unsafe { bindings::hrtimer_cancel(c_timer_ptr) != 0 } > + } > +} > + > +/// Implemented by pointer types that point to structs that embed a [`Timer`]. > +/// > +/// Typical implementers would be [`Box`], [`Arc`], [`ARef`] where `T` > +/// has a field of type `Timer`. > +/// > +/// Target must be [`Sync`] because timer callbacks happen in another thread of > +/// execution (hard or soft interrupt context). > +/// > +/// Starting a timer returns a [`TimerHandle`] that can be used to manipulate > +/// the timer. Note that it is OK to call the start function repeatedly, and > +/// that more than one [`TimerHandle`] associated with a `TimerPointer` may > +/// exist. A timer can be manipulated through any of the handles, and a handle > +/// may represent a cancelled timer. > +/// > +/// [`Box`]: Box > +/// [`Arc`]: crate::sync::Arc > +/// [`ARef`]: crate::types::ARef > +pub trait TimerPointer: Sync + Sized { > + /// A handle representing a running timer. > + /// > + /// If the timer is running or if the timer callback is executing when the > + /// handle is dropped, the drop method of `TimerHandle` should not return > + /// until the timer is stopped and the callback has completed. > + /// > + /// Note: It must be safe to leak the handle. > + type TimerHandle: TimerHandle; > + > + /// Start the timer with expiry after `expires` time units. If the timer was > + /// already running, it is restarted with the new expiry time. > + fn start(self, expires: Ktime) -> Self::TimerHandle; > +} > + > +/// Implemented by [`TimerPointer`] implementers to give the C timer callback a > +/// function to call. > +// This is split from `TimerPointer` to make it easier to specify trait bounds. > +pub trait RawTimerCallback { RawHrtimerCallback ? > + /// Callback to be called from C when timer fires. > + /// > + /// # Safety > + /// > + /// Only to be called by C code in `hrtimer` subsystem. `ptr` must point to > + /// the `bindings::hrtimer` structure that was used to start the timer. > + unsafe extern "C" fn run(ptr: *mut bindings::hrtimer) -> bindings::hrtimer_restart; > +} > + > +/// Implemented by structs that can the target of a timer callback. > +pub trait TimerCallback { HrtimerCallback ? etc... Thanks.