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 40A9C1A9FAB for ; Thu, 21 Aug 2025 19:33:37 +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=1755804819; cv=none; b=EWiHQ5jGnGzXRByOaanmj537Qx/SRp9/NbwD5dapB9dfzpOh+RckM8UJwCJA4wpADCNPrIDCHZBRUFpzxdDY+GGGvDe0InTY8fs9Ar7eivFu9ehA36NEwyeC13N78Q1Qk9zG/glwA0NMpfZkPhrQcsx7xYiLSVb5dPjdTUOYSds= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755804819; c=relaxed/simple; bh=1namyJhBXNTlgxWA4Sts203ok2F3Onjou2+vIHGaWMM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=sWw+OjkaIcqFY0NvyJswwALo+y/0CCcnmzVgysiYPSW9uwsjZhhuTyOFLzD/JY/6TgnlhzhAZgmTiGOttfFGua8iBwZdUE4wQP6EJFzhb9lNVonhxeJHaNEazNI3lvIW6EQYD2uckRUGYrqG4bis6DqJJMayPvt50JKOuYyMEYc= 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=EnKNVs7r; 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="EnKNVs7r" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1755804817; 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=IdZatwK7YZ40vNNmIn9rSFrBBk7bYVx1796BmwT3dbI=; b=EnKNVs7rO2jpadmUh+494tikqWGjUOR3jiuEmt7+r72q2tR4DeSQZ+9eXHma8Pxshi0cbF ynVhgcqG2k9IGaA/Nk1m0YyLkw+U64F36LyxYaZvVwHcfCC0uF8ehyGSj41bFK/FyEtwg5 im6Imh3leGSzqDJwr9vGbXp6GJVAYc4= 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-50-aHDaGrXrOeS9cJjhdq6Mxg-1; Thu, 21 Aug 2025 15:33:34 -0400 X-MC-Unique: aHDaGrXrOeS9cJjhdq6Mxg-1 X-Mimecast-MFC-AGG-ID: aHDaGrXrOeS9cJjhdq6Mxg_1755804810 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (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 114871956080; Thu, 21 Aug 2025 19:33:30 +0000 (UTC) Received: from chopper.redhat.com (unknown [10.22.89.200]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id D2146197768A; Thu, 21 Aug 2025 19:33:25 +0000 (UTC) From: Lyude Paul To: Cc: Daniel Almeida , Andreas Hindborg , 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 , rust-for-linux@vger.kernel.org (open list:DELAY, SLEEP, TIMEKEEPING, TIMERS [RUST]), linux-kernel@vger.kernel.org (open list) Subject: [PATCH v9 3/7] rust: hrtimer: Add HrTimer::raw_forward() and forward() Date: Thu, 21 Aug 2025 15:32:43 -0400 Message-ID: <20250821193259.964504-4-lyude@redhat.com> In-Reply-To: <20250821193259.964504-1-lyude@redhat.com> References: <20250821193259.964504-1-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 10.30.177.17 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 Reviewed-by: Daniel Almeida --- 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) V6: * Remove the reference to HrTimerCallbackContext::forward() until this function gets added. V7 * Split up Timer::forward() a bit, apply Andreas's SAFETY comment recommendations rust/kernel/time/hrtimer.rs | 40 +++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs index be1bad4aacaad..79fed14b2d98e 100644 --- a/rust/kernel/time/hrtimer.rs +++ b/rust/kernel/time/hrtimer.rs @@ -168,6 +168,46 @@ 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: HrTimerInstant, interval: Delta) -> u64 + where + T: HasHrTimer, + { + // 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`. + /// + /// Returns the number of overruns that occurred as a result of the timer expiry change. + pub fn forward(self: Pin<&mut Self>, now: HrTimerInstant, interval: Delta) -> u64 + where + T: HasHrTimer, + { + // SAFETY: `raw_forward` does not move `Self` + let this = unsafe { self.get_unchecked_mut() }; + + // SAFETY: By existence of `Pin<&mut Self>`, the pointer passed to `raw_forward` points to a + // valid `Self` that we have exclusive access to. + unsafe { Self::raw_forward(this, now, interval) } + } } /// Implemented by pointer types that point to structs that contain a [`HrTimer`]. -- 2.50.0