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 6F409264609 for ; Tue, 29 Apr 2025 21:48:14 +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=1745963296; cv=none; b=MXVRzZhh2UwQtki3DWSxRf3oa8wbi+/pVOtV/QvQBG6zWq15mE/3LdexZduch5yiiXnBCxXaJ97oYGCber/00Au9VuLA8ck1vJ108yWwwTNKeNczdLE7lyrUpJDWcdlkqaH3wpkhCC13JuarVbTzywxy4Kdx4cfC/yk6up4SVHA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745963296; c=relaxed/simple; bh=MSF0qwmCf6ZWXrtsVfIP/yBIfGWSyTA2Js4oFfyZz3M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jC+RC3CfJR2jXII2qF5PxoDyF5R9X3EKizdPC9OZmf0eicgQArkCNnKUjDAxrnuKN7nHGVBKPxtWpb8s+DrAZ2Sbpcij0+dkbBfkT8Xem/xUxi8loz0J1URv6id3SrAZTHxPuKy4ECkqtIol2ZCBZRO+Ab5cuGVo3YJLjmYbTvw= 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=dGszl4de; 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="dGszl4de" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1745963293; 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=gZb82PbyGYSBKPulXkIr1Fg1XkWaJSRhe1YdKH7R7kE=; b=dGszl4deY0bQl/Gi1Eg8Pln2wl6lASi3ww034mjpYQ7gVgVvUH1QklYTW9MvGWZ5vHeReG oMi5CO7VKrU4Y7IK97/TS1STx6ag3SU9nLxFa1qjscDW4mY8wvmZ7Cs4fl05eca1p/pl3x F/goWV6SkeUQf5wt0Ca0nu9r9bG/1bw= 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-662-5sbtlesFPNCQxhQ6mYB1hw-1; Tue, 29 Apr 2025 17:48:10 -0400 X-MC-Unique: 5sbtlesFPNCQxhQ6mYB1hw-1 X-Mimecast-MFC-AGG-ID: 5sbtlesFPNCQxhQ6mYB1hw_1745963287 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-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 3A1391956094; Tue, 29 Apr 2025 21:48:07 +0000 (UTC) Received: from chopper.redhat.com (unknown [10.22.88.132]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 6767E19560A3; Tue, 29 Apr 2025 21:48:03 +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 v4 2/7] rust: hrtimer: Add HrTimer::raw_forward() and forward() Date: Tue, 29 Apr 2025 17:44:38 -0400 Message-ID: <20250429214752.1637859-3-lyude@redhat.com> In-Reply-To: <20250429214752.1637859-1-lyude@redhat.com> References: <20250429214752.1637859-1-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: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 Within the hrtimer API there are quite a number of functions that can only be safely called from one of two contexts: * When we have exclusive access to the hrtimer and the timer is not active. * When we're within the hrtimer's callback context as it is being executed. This commit adds bindings for hrtimer_forward() for the first such context, along with HrTimer::raw_forward() for later use in implementing the hrtimer_forward() in the latter context. Signed-off-by: Lyude Paul --- V4: * Fix the safety contract for raw_forward() * Require Pin<&mut Self>, not &mut self * Drop incorrect UniquePin example * Rewrite documentation a bit (re: Andreas) Signed-off-by: Lyude Paul --- rust/kernel/time/hrtimer.rs | 44 ++++++++++++++++++++++++++++++++++++- 1 file changed, 43 insertions(+), 1 deletion(-) diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs index ef96c7e2c21ff..76caf9fae8170 100644 --- a/rust/kernel/time/hrtimer.rs +++ b/rust/kernel/time/hrtimer.rs @@ -68,7 +68,11 @@ //! `start` operation. use super::ClockId; -use crate::{prelude::*, time::Instant, types::Opaque}; +use crate::{ + prelude::*, + time::{Delta, Instant}, + types::Opaque, +}; use core::marker::PhantomData; use pin_init::PinInit; @@ -164,6 +168,44 @@ pub(crate) unsafe fn raw_cancel(this: *const Self) -> bool { // handled on the C side. unsafe { bindings::hrtimer_cancel(c_timer_ptr) != 0 } } + + /// Forward the timer expiry for a given timer pointer. + /// + /// # Safety + /// + /// - `self_ptr` must point to a valid `Self`. + /// - The caller must either have exclusive access to the data pointed at by `self_ptr`, or be + /// within the context of the timer callback. + #[inline] + unsafe fn raw_forward(self_ptr: *mut Self, now: Instant, interval: Delta) -> u64 { + // SAFETY: + // * The C API requirements for this function are fulfilled by our safety contract. + // * `self_ptr` is guaranteed to point to a valid `Self` via our safety contract + unsafe { + bindings::hrtimer_forward(Self::raw_get(self_ptr), now.as_nanos(), interval.as_nanos()) + } + } + + /// Conditionally forward the timer. + /// + /// If the timer expires after `now`, this function does nothing and returns 0. If the timer + /// expired at or before `now`, this function forwards the timer by `interval` until the timer + /// expires after `now` and then returns the number of times the timer was forwarded by + /// `interval`. + /// + /// This function is mainly useful for timer types which can provide exclusive access to the + /// timer when the timer is not running. For forwarding the timer from within the timer callback + /// context, see [`HrTimerCallbackContext::forward()`]. + /// + /// Returns the number of overruns that occurred as a result of the timer expiry change. + pub fn forward(self: Pin<&mut Self>, now: Instant, interval: Delta) -> u64 { + // SAFETY: + // - `raw_forward` does not move `self`. + // - Self is a mutable reference and thus always points to a valid `HrTimer` + // - The only way that we could hold a mutable reference to `HrTimer` is if we have + // exclusive access to it - fulfilling the requirements of the C API. + unsafe { Self::raw_forward(self.get_unchecked_mut(), now, interval) } + } } /// Implemented by pointer types that point to structs that contain a [`HrTimer`]. -- 2.48.1