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 A2D772EE263 for ; Thu, 24 Jul 2025 18:53:06 +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=1753383188; cv=none; b=GN8XRHiOod/YrjHw8hgdsjRxn+C4RGYULaoMXZ0UqSuC7c1nzm16M8DHlzkaP9qjdWKanUuvjbhYuXCUdLK9WrL3qrkuFAvqSbKLwecq2ZSwWNCQ7lGpdUEeKKCQvqEaZmg4bX3632P8j5KqCMyMO65LhiTvUm3ci6inG9nxres= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753383188; c=relaxed/simple; bh=I6r/hVojm9kPsiME3lDLV24WqEKZE1S6dw/IIfQTPIg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=n2w6MGnHi6DYGimmUqAAYnrF/Ukj5BFJF6BwVoCtWwLvazcUgteBgi4QfcrMPuvZWOp74RJgSTrrK3BO9V0kGj85Y/o1I7GsY3WueTPxOnitSzSnFBKu/xm2Nf3uv87MjrNizxoghEOKRAdhejo7jzwE6EkrHYZhx6wSDROBUxw= 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=JVHE62GW; 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="JVHE62GW" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1753383185; 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=SIvhLLPtzfNF63KacAB5y6ueD7cnnwqEnQG82pg+xts=; b=JVHE62GWTYA0nH7Yh7FX8cibOzWKvHhwPUM1uohYRV8zr389tbHmUkEvTecKRRSYPcS5MX /2gmeWtkhC49LjP6AnjkxBub+AHdf7Q2pXfMKJKNJnbwPiOVnrWfWwvsZhDMqjMKwOobFL JI3mmwjfbcRtDF5gvNrVgSMNoEBl3Wo= 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-408-WA3DVNVAPbi3ox1JdACujA-1; Thu, 24 Jul 2025 14:52:59 -0400 X-MC-Unique: WA3DVNVAPbi3ox1JdACujA-1 X-Mimecast-MFC-AGG-ID: WA3DVNVAPbi3ox1JdACujA_1753383175 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 B6CDC180098E; Thu, 24 Jul 2025 18:52:55 +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 76AA21956096; Thu, 24 Jul 2025 18:52:51 +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 3/7] rust: hrtimer: Add HrTimer::raw_forward() and forward() Date: Thu, 24 Jul 2025 14:49:29 -0400 Message-ID: <20250724185236.556482-4-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 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) V6: * Remove the reference to HrTimerCallbackContext::forward() until this function gets added. Signed-off-by: Lyude Paul --- 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..5ccdd1b0b8021 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`. + // - 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`]. -- 2.50.0