From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 0B70337188A; Fri, 26 Jun 2026 10:52:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782471127; cv=none; b=OCB+n/0uBT6QCBwy0kWjTYbtrEr+kyHYUmKbbEJEgkAdcHXwuIcBqLy3ALzz0y9cGc1wH1lWeKLlEHkpcFoVQ8Gv4NzwJSP6vbhUpTyPCDpYnXngVQCwks8ut4wbaTMEDnlqim/nyJx4qkeLkJrgu2l7MIb4cNdWNplK+6FTVXQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782471127; c=relaxed/simple; bh=u/6Vcsvfi9MhRelYL5eXpQCPOzlekhX3VQNSa4eanq4=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=OEwTHlyFAiGVJcRpg5+OpsfRKxiMWaB0lB147YBV6x3p9cBoNBBFidk2BzIzyAmCwfEYOWzk784/8yUpk4D4JC2XcEbXxtdwf/XdU67fcdBvfxWfA3b9L0Efnpxh9PPgFMkg2vOejOPf+3AT5oeuJvSFtzTVSk3+Y9Ghds5n/oU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=casper.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=nLEMOTF7; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=casper.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="nLEMOTF7" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=MIME-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=u/6Vcsvfi9MhRelYL5eXpQCPOzlekhX3VQNSa4eanq4=; b=nLEMOTF7/CByLzLTQFBZxSpOju Ub4QL9jAScdTl3qQe3MkBkDKj5fGktBGSZkuXRRB4cLM+ZLKZKcKqAALXC3SWMh3sShXsU/ZKCB47 osI0I/av8ssah9W4P31gUh3+T9q674RyjvU+0AinoXhq5zTxbR8eu7P569lqJTSjOIzqiMNMGmHHi lfcQ9/XIoKjT3Y5WBAxQOtojHNq5qFvkj3j4GEQ4sT84bYxUJyqOmmkw1nytDZachFkiwStMBs4Fz aA3sdzF09p1Cw5q6qGPaPojWjDdwOApD9GkLqxvjrMtE/7z6n2/6mdyNanPAkGSSWwBi/mISnYEX4 W9K/opfw==; Received: from [2001:8b0:10b:5:f3d6:3c0c:6c61:8d10] (helo=u09cd745991455d.ant.amazon.com) by casper.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1wd4AB-0000000BgPS-1Neh; Fri, 26 Jun 2026 10:51:59 +0000 Message-ID: <7b4538d42b25d711d0aa2fee5ec03a84230083fe.camel@infradead.org> Subject: Re: [patch 09/24] timekeeping: Add CLOCK_AUX support for ktime_get_snapshot_id() From: David Woodhouse To: Thomas =?ISO-8859-1?Q?Wei=DFschuh?= , Thomas Gleixner Cc: LKML , Miroslav Lichvar , John Stultz , Stephen Boyd , Anna-Maria Behnsen , Frederic Weisbecker , Arthur Kiyanovski , Rodolfo Giometti , Vincent Donnefort , Marc Zyngier , Oliver Upton , kvmarm@lists.linux.dev, Oliver Upton , Richard Cochran , netdev@vger.kernel.org, Takashi Iwai , Miri Korenblit , Johannes Berg , Jacob Keller , Tony Nguyen , Saeed Mahameed , Peter Hilber , "Michael S. Tsirkin" , virtualization@lists.linux.dev, linux-wireless@vger.kernel.org, linux-sound@vger.kernel.org Date: Fri, 26 Jun 2026 11:51:57 +0100 In-Reply-To: <20260626103359-66ab2b54-d36f-416b-94a4-3f3708dccced@linutronix.de> References: <20260526165826.392227559@kernel.org> <20260526171223.374814973@kernel.org> <20260626103359-66ab2b54-d36f-416b-94a4-3f3708dccced@linutronix.de> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-+6FvWBNSZK7HpnU+jSU6" User-Agent: Evolution 3.60.3-0ubuntu1~ppa6 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html --=-+6FvWBNSZK7HpnU+jSU6 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Fri, 2026-06-26 at 10:48 +0200, Thomas Wei=C3=9Fschuh wrote: > 'tkd' is also used to compute 'monoraw'. However 'tkr_raw' and 'tkr_mono' > are the same for auxilary clocks, so this will compute a wrong 'monoraw'. > Instead 'monoraw' should be computed based on 'tk_core'. > Which then also requires the sequence locking of 'tk_core'. >=20 > As you know I have a series which unifies the locking between the > different timekeepers. Maybe we revert this patch for 7.2 and I send > a fixed variant including the prerequisites for 7.3. >=20 > (The same goes for get_device_system_crosststamp()) No fundamental objection from me... but does it matter in practice? Is it even reachable? I think the only way these functions can end up being invoked for aux clocks is via PTP_SYS_OFFSET_EXTENDED, which since commit a6d799608e6 ("ptp: Switch to ktime_get_snapshot_id() for pre/post timestamps") and some other driver-specific changes in this series, can now invoke them with the user-requested clockid. But those callers *only* care about ::systime, don't they? So the problem never arises because there's no code path in which anything actually cares about ::monoraw for AUX clocks. If we back out the handling of AUX clocks in ktime_get_snapshot_id() we'd have to roll back much of that other plumbing too. If we *just* remove the 'case CLOCK_AUX ... CLOCK_AUX_LAST' hunk, we'd end up with users being able to trigger the 'default: WARN_ON_ONCE(1)' which follows. So while you're right, I *think* it's harmless in practice and reverting it safely is slightly more complex than it seems at first glance? --=-+6FvWBNSZK7HpnU+jSU6 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCD9Aw ggSOMIIDdqADAgECAhAOmiw0ECVD4cWj5DqVrT9PMA0GCSqGSIb3DQEBCwUAMGUxCzAJBgNVBAYT AlVTMRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5jb20xJDAi BgNVBAMTG0RpZ2lDZXJ0IEFzc3VyZWQgSUQgUm9vdCBDQTAeFw0yNDAxMzAwMDAwMDBaFw0zMTEx MDkyMzU5NTlaMEExCzAJBgNVBAYTAkFVMRAwDgYDVQQKEwdWZXJva2V5MSAwHgYDVQQDExdWZXJv a2V5IFNlY3VyZSBFbWFpbCBHMjCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMjvgLKj jfhCFqxYyRiW8g3cNFAvltDbK5AzcOaR7yVzVGadr4YcCVxjKrEJOgi7WEOH8rUgCNB5cTD8N/Et GfZI+LGqSv0YtNa54T9D1AWJy08ZKkWvfGGIXN9UFAPMJ6OLLH/UUEgFa+7KlrEvMUupDFGnnR06 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