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 C455D2ED843 for ; Thu, 24 Jul 2025 18:53:29 +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=1753383211; cv=none; b=dieaLjTc+y2dzwRYrerPtmHmv11tsrBzZBAkaJCt5fGfeZWi9SPEuGL4fS2yE4srE6KLbuzDnGIpUUnKOVE0RPmuoRxIxHUC+LttCjbRKD3gRL3IIWp1PZuuGKr0xzlPmzsOESkMJh2pqo33M/KEcewKPqUW9NlCTFOXf2W9x0s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753383211; c=relaxed/simple; bh=mUCzRYYIfWZf5GOkc293zl7pIfmGz+Gij1JSIuPXYco=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=tQ+KFOOFQ1RHOgYLmDANrCODZqd/AJHRG/jk7Uk+vi28UUpEHEjNSNRZgqc6X03c5YSSInTtP23wuf5N7PjJfZKoXAP3cC5Qefle6lo2USjaaSsrhIOyDYkHGbc+4H0i7ULsJ6m0oV8q0KRqRShS9pOma+rEB14wJ1lw0NY2hqc= 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=ZP89sSfK; 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="ZP89sSfK" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1753383208; 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=rZ2yVlJPs2PJNhdTn0DP3jFnAjUYOrYzBe58F8qZCwE=; b=ZP89sSfKqPDRhwdboSYyZe/krUJwk9R/wr0uI04v0VKlNB4/ilFQaLODhA+lZBSouwbsAz p1JIcyGduGnCtd835CV8jpQrgM+V/fJEEk+Dv1zTLys0UUujIY3Ano9rTjiNeICS8HxVkn mRyefmfpb4sp/aSM2WJZQi6+CKtHMcU= 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-656-wIqSM_-TOYuW2bJkayz6_Q-1; Thu, 24 Jul 2025 14:53:24 -0400 X-MC-Unique: wIqSM_-TOYuW2bJkayz6_Q-1 X-Mimecast-MFC-AGG-ID: wIqSM_-TOYuW2bJkayz6_Q_1753383201 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-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C5F531800264; Thu, 24 Jul 2025 18:53:21 +0000 (UTC) Received: from chopper.lyude.net (unknown [10.22.88.223]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 0575B1956096; Thu, 24 Jul 2025 18:53:17 +0000 (UTC) From: Lyude Paul To: rust-for-linux@vger.kernel.org, Thomas Gleixner , Boqun Feng , linux-kernel@vger.kernel.org, Andreas Hindborg , FUJITA Tomonori Cc: Frederic Weisbecker , 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 v6 7/7] rust: hrtimer: Add HrTimer::expires() Date: Thu, 24 Jul 2025 14:49:33 -0400 Message-ID: <20250724185236.556482-8-lyude@redhat.com> In-Reply-To: <20250724185236.556482-1-lyude@redhat.com> References: <20250724185236.556482-1-lyude@redhat.com> Precedence: bulk X-Mailing-List: rust-for-linux@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 Add a simple callback for retrieving the current expiry time for an HrTimer. In rvkms, we use the HrTimer expiry value in order to calculate the approximate vblank timestamp during each emulated vblank interrupt. Signed-off-by: Lyude Paul --- rust/kernel/time.rs | 1 - rust/kernel/time/hrtimer.rs | 23 +++++++++++++++++++++++ 2 files changed, 23 insertions(+), 1 deletion(-) diff --git a/rust/kernel/time.rs b/rust/kernel/time.rs index 75088d080b834..6d6e71710ebdc 100644 --- a/rust/kernel/time.rs +++ b/rust/kernel/time.rs @@ -211,7 +211,6 @@ pub(crate) fn as_nanos(&self) -> i64 { /// # Safety /// /// The caller promises that `nanos` is in the range from 0 to `KTIME_MAX`. - #[expect(unused)] #[inline] pub(crate) unsafe fn from_nanos(nanos: i64) -> Self { debug_assert!(nanos >= 0); diff --git a/rust/kernel/time/hrtimer.rs b/rust/kernel/time/hrtimer.rs index fa5a3ae81723b..2d52a1b3b39a0 100644 --- a/rust/kernel/time/hrtimer.rs +++ b/rust/kernel/time/hrtimer.rs @@ -223,6 +223,29 @@ pub fn forward_now(self: Pin<&mut Self>, interval: Delta) -> u64 { self.forward(HrTimerInstant::::now(), interval) } + + /// Return the time expiry for this [`HrTimer`]. + /// + /// This value should only be used as a snapshot, as the actual expiry time could change after + /// this function is called. + pub fn expires(&self) -> HrTimerInstant + where + T: HasHrTimer, + { + // SAFETY: `self` is an immutable reference and thus always points to a valid `HrTimer`. + let c_timer_ptr = unsafe { HrTimer::raw_get(self) }; + + // SAFETY: + // - `node.expires` is a ktime_t, so it must be within the range of `0` to `KTIME_MAX`. + // - There's no actual locking here, a racy read is fine and expected + unsafe { + Instant::from_nanos( + // This `read_volatile` is intended to correspond to a READ_ONCE call. + // FIXME(read_once): Replace with `read_once` when available on the Rust side. + core::ptr::read_volatile(&raw const ((*c_timer_ptr).node.expires)), + ) + } + } } /// Implemented by pointer types that point to structs that contain a [`HrTimer`]. -- 2.50.0