From nobody Fri Dec 19 20:52:37 2025 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 AE0722512DC for ; Tue, 15 Apr 2025 19:51:01 +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=1744746663; cv=none; b=cw0UPmvZl8eeji/4sEpcIXl7eYw7BMpnV+o4Oc1ovikWEOoF3dhwk/v37iOKLLKCEk6iMnA7nIXpy6iSjB9QSRPnbbYgpqYQWuDk9pB8E9KnQFOQSK3FNMKUse/58acrEHw831GSKM1ECG9BDMBtOsRZA3vt46VKAwe/vRG/yzo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744746663; c=relaxed/simple; bh=7qcwkn32Fa0sfbLRLUeoYAai3MiiIaWCqHs+F9VCGZ8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MprIqeIdif50wYPTPcoaY66UTrmDvcTd0K44ekbBTqm0Q32eIQWPf1ZVqx0L/UoeuQf7on/Fjk8KniOFqTfpQc2kFu8p4t8KyeUTn2vmGXxuC5fI+BnOe3R6iICjXXiX/J8GTDAojbkNPDtnkdVZFBn59S759qtiKIJRw+yksZs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine 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=htnxiwXR; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine 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="htnxiwXR" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744746660; 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=2ryYGmJ3J41KdHRoTFjagDnmKVKLfVIOtjqIQ3uqQjs=; b=htnxiwXRHzmL18ESvinLfTeO6MJnDzgFwf0mrkMqmD+rQYLRhaSxL0+WOUUQSetgw7MFS2 6GOrmpLyDYN34pV2aoIXjQ57JjRa96fZCXNX68Oma9VhwEgr5CqVsT8eT6rVqk06lrgSAP jaAy+XtAex2KxoSQi6g2+Be5xpa7F+U= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-250-zmeoNb1RNfaU2f96RZ3cZg-1; Tue, 15 Apr 2025 15:50:53 -0400 X-MC-Unique: zmeoNb1RNfaU2f96RZ3cZg-1 X-Mimecast-MFC-AGG-ID: zmeoNb1RNfaU2f96RZ3cZg_1744746651 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 37CDD1800A38; Tue, 15 Apr 2025 19:50:49 +0000 (UTC) Received: from chopper.redhat.com (unknown [10.22.88.101]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 2EC3919560AD; Tue, 15 Apr 2025 19:50:45 +0000 (UTC) From: Lyude Paul To: rust-for-linux@vger.kernel.org, Andreas Hindborg , linux-kernel@vger.kernel.org Cc: Boqun Feng , FUJITA Tomonori , Frederic Weisbecker , Thomas Gleixner , Anna-Maria Behnsen , John Stultz , Stephen Boyd , Miguel Ojeda , Alex Gaynor , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Alice Ryhl , Trevor Gross , Danilo Krummrich Subject: [PATCH v2 3/8] rust: hrtimer: Add HrTimerCallbackContext and ::forward() Date: Tue, 15 Apr 2025 15:48:24 -0400 Message-ID: <20250415195020.413478-4-lyude@redhat.com> In-Reply-To: <20250415195020.413478-1-lyude@redhat.com> References: <20250415195020.413478-1-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 10.30.177.40 Content-Type: text/plain; charset="utf-8" With Linux's hrtimer API, there's a number of methods that can only be called in two situations: * When we have exclusive access to the hrtimer and it is not currently active * When we're within the context of an hrtimer callback context This commit handles the second situation and implements hrtimer_forward() support in the context of a timer callback. We do this by introducing a HrTimerCallbackContext type which is provided to users during the RawHrTimerCallback::run() callback, and then add a forward() function to the type. Signed-off-by: Lyude Paul --- V2: * Improve SAFETY comments for HrTimerCallbackContext uses (I forgot to mention that we're within RawHrTimerCallback::run() * Split forward into forward() and raw_forward() since we're going to have two contexts that we can call forward() from now. * Clarify contexts in which certain hrtimer methods can be called. * Make sure that we use a mutable reference for forward() here - just in case :). * Rename interval to duration Signed-off-by: Lyude Paul --- rust/kernel/time/hrtimer.rs | 51 +++++++++++++++++++++++++++-- rust/kernel/time/hrtimer/arc.rs | 9 ++++- rust/kernel/time/hrtimer/pin.rs | 9 ++++- rust/kernel/time/hrtimer/pin_mut.rs | 11 +++++-- rust/kernel/time/hrtimer/tbox.rs | 9 ++++- 5 files changed, 82 insertions(+), 7 deletions(-) diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs index aadae8666f7ea..507fff67f8ab2 100644 --- a/rust/kernel/time/hrtimer.rs +++ b/rust/kernel/time/hrtimer.rs @@ -73,7 +73,7 @@ time::{Delta, Instant}, types::Opaque, }; -use core::marker::PhantomData; +use core::{marker::PhantomData, ptr::NonNull}; use pin_init::PinInit; =20 /// A timer backed by a C `struct hrtimer`. @@ -314,7 +314,10 @@ pub trait HrTimerCallback { type Pointer<'a>: RawHrTimerCallback; =20 /// Called by the timer logic when the timer fires. - fn run(this: as RawHrTimerCallback>::CallbackTarget= <'_>) -> HrTimerRestart + fn run( + this: as RawHrTimerCallback>::CallbackTarget<'_= >, + ctx: HrTimerCallbackContext<'_, T>, + ) -> HrTimerRestart where Self: Sized; } @@ -507,6 +510,50 @@ fn into_c(self) -> bindings::hrtimer_mode { } } =20 +/// Privileged smart-pointer for a [`HrTimer`] callback context. +/// +/// Many [`HrTimer`] methods can only be called in two situations: +/// +/// * When the caller has exclusive access to the `HrTimer` and the `HrTim= er` is guaranteed not to +/// be running. +/// * From within the context of an `HrTimer`'s callback method. +/// +/// This type provides access to said methods from within a timer callback= context. +/// +/// # Invariants +/// +/// * The existence of this type means the caller is currently within the = callback for an +/// [`HrTimer`]. +/// * `self.0` always points to a live instance of [`HrTimer`]. +pub struct HrTimerCallbackContext<'a, T>(NonNull>, PhantomData<= &'a ()>); + +impl<'a, T> HrTimerCallbackContext<'a, T> { + /// Create a new [`HrTimerCallbackContext`]. + /// + /// # Safety + /// + /// This function relies on the caller being within the context of a t= imer callback, so it must + /// not be used anywhere except for within implementations of [`RawHrT= imerCallback::run`]. The + /// caller promises that `timer` points to a valid initialized instanc= e of + /// [`bindings::hrtimer`]. + pub(crate) unsafe fn from_raw(timer: *mut HrTimer) -> Self { + // SAFETY: The caller guarantees `timer` is a valid pointer to an = initialized + // `bindings::hrtimer` + Self(unsafe { NonNull::new_unchecked(timer) }, PhantomData) + } + + /// Forward the timer expiry so it expires at `duration` after `now`. + /// + /// Note that this does not requeue the timer, it simply updates its e= xpiry value. It returns + /// the number of overruns that have occurred as a result of the expir= y change. + pub fn forward(&mut self, now: Instant, duration: Delta) -> u64 { + // SAFETY: + // - We are guaranteed to be within the context of a timer callbac= k by our type invariants + // - By our type invariants, `self.0` always points to a valid `Hr= Timer` + unsafe { HrTimer::::raw_forward(self.0.as_ptr(), now, duration)= } + } +} + /// Use to implement the [`HasHrTimer`] trait. /// /// See [`module`] documentation for an example. diff --git a/rust/kernel/time/hrtimer/arc.rs b/rust/kernel/time/hrtimer/arc= .rs index acc70a0ea1be5..f30efd2d1094d 100644 --- a/rust/kernel/time/hrtimer/arc.rs +++ b/rust/kernel/time/hrtimer/arc.rs @@ -3,6 +3,7 @@ use super::HasHrTimer; use super::HrTimer; use super::HrTimerCallback; +use super::HrTimerCallbackContext; use super::HrTimerHandle; use super::HrTimerPointer; use super::RawHrTimerCallback; @@ -95,6 +96,12 @@ impl RawHrTimerCallback for Arc // allocation from other `Arc` clones. let receiver =3D unsafe { ArcBorrow::from_raw(data_ptr) }; =20 - T::run(receiver).into_c() + // SAFETY: + // - By C API contract `timer_ptr` is the pointer that we passed w= hen queuing the timer, so + // it is a valid pointer to a `HrTimer` embedded in a `T`. + // - We are within `RawHrTimerCallback::run` + let context =3D unsafe { HrTimerCallbackContext::from_raw(timer_pt= r) }; + + T::run(receiver, context).into_c() } } diff --git a/rust/kernel/time/hrtimer/pin.rs b/rust/kernel/time/hrtimer/pin= .rs index dba22d11a95f5..c694a96fcd9d5 100644 --- a/rust/kernel/time/hrtimer/pin.rs +++ b/rust/kernel/time/hrtimer/pin.rs @@ -3,6 +3,7 @@ use super::HasHrTimer; use super::HrTimer; use super::HrTimerCallback; +use super::HrTimerCallbackContext; use super::HrTimerHandle; use super::RawHrTimerCallback; use super::UnsafeHrTimerPointer; @@ -99,6 +100,12 @@ impl<'a, T> RawHrTimerCallback for Pin<&'a T> // here. let receiver_pin =3D unsafe { Pin::new_unchecked(receiver_ref) }; =20 - T::run(receiver_pin).into_c() + // SAFETY: + // - By C API contract `timer_ptr` is the pointer that we passed w= hen queuing the timer, so + // it is a valid pointer to a `HrTimer` embedded in a `T`. + // - We are within `RawHrTimerCallback::run` + let context =3D unsafe { HrTimerCallbackContext::from_raw(timer_pt= r) }; + + T::run(receiver_pin, context).into_c() } } diff --git a/rust/kernel/time/hrtimer/pin_mut.rs b/rust/kernel/time/hrtimer= /pin_mut.rs index aeff8e102e1dc..82242c79ee433 100644 --- a/rust/kernel/time/hrtimer/pin_mut.rs +++ b/rust/kernel/time/hrtimer/pin_mut.rs @@ -1,7 +1,8 @@ // SPDX-License-Identifier: GPL-2.0 =20 use super::{ - HasHrTimer, HrTimer, HrTimerCallback, HrTimerHandle, RawHrTimerCallbac= k, UnsafeHrTimerPointer, + HasHrTimer, HrTimer, HrTimerCallback, HrTimerCallbackContext, HrTimerH= andle, + RawHrTimerCallback, UnsafeHrTimerPointer, }; use crate::time::Instant; use core::{marker::PhantomData, pin::Pin, ptr::NonNull}; @@ -103,6 +104,12 @@ impl<'a, T> RawHrTimerCallback for Pin<&'a mut T> // here. let receiver_pin =3D unsafe { Pin::new_unchecked(receiver_ref) }; =20 - T::run(receiver_pin).into_c() + // SAFETY: + // - By C API contract `timer_ptr` is the pointer that we passed w= hen queuing the timer, so + // it is a valid pointer to a `HrTimer` embedded in a `T`. + // - We are within `RawHrTimerCallback::run` + let context =3D unsafe { HrTimerCallbackContext::from_raw(timer_pt= r) }; + + T::run(receiver_pin, context).into_c() } } diff --git a/rust/kernel/time/hrtimer/tbox.rs b/rust/kernel/time/hrtimer/tb= ox.rs index 3df4e359e9bb0..c5c952721cee2 100644 --- a/rust/kernel/time/hrtimer/tbox.rs +++ b/rust/kernel/time/hrtimer/tbox.rs @@ -3,6 +3,7 @@ use super::HasHrTimer; use super::HrTimer; use super::HrTimerCallback; +use super::HrTimerCallbackContext; use super::HrTimerHandle; use super::HrTimerPointer; use super::RawHrTimerCallback; @@ -115,6 +116,12 @@ impl RawHrTimerCallback for Pin> // `data_ptr` exist. let data_mut_ref =3D unsafe { Pin::new_unchecked(&mut *data_ptr) }; =20 - T::run(data_mut_ref).into_c() + // SAFETY: + // - By C API contract `timer_ptr` is the pointer that we passed w= hen queuing the timer, so + // it is a valid pointer to a `HrTimer` embedded in a `T`. + // - We are within `RawHrTimerCallback::run` + let context =3D unsafe { HrTimerCallbackContext::from_raw(timer_pt= r) }; + + T::run(data_mut_ref, context).into_c() } } --=20 2.48.1