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 A85F03EFFC8; Thu, 28 May 2026 17:22:18 +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=1779988940; cv=none; b=TlkZlpewet79BFugdxZGPnVbtKPfj4dHsE0MdLzhEwbyFy3l1HT8CbCwEC47u0mabE/rjhqQUOsizlfPQjzbhAz0OCgXlz2hTXVdLjIOrNF22giCHMrjT3hejUgC6jcBAoSP/GCr32GeX/pwVe9aLkoPwB65q+qf2V/3XtKm4ug= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779988940; c=relaxed/simple; bh=i1P5+Xznndi8odiiiRl63REcOgMYs/V8a2xT/cXVUtc=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=ed14aNNO21HMx++G9rHLVQGqMi9rxPcYTRIQ1xSjkYg/FYnSMY70n9LTVQvDptrtrlASzT2xxRA0ZEZwzUaPEqlI46V4Pp4s6s1ZqJ2oQ2NqJFDna50FqSqETpXZw/FY4nQMnZBgVGcYRC9WgCYrnytblvDdMYBvWuwsTnAL1L0= 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=Mvg/QVln; 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="Mvg/QVln" 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=NYNUrl4i6PMnZ8nmqslcPbXTjjZX8ZFyFrdYrGsoxVo=; b=Mvg/QVlnTKhM/JFh0dhCXZmXpU Jz2wWtEPpf0q+XSXPyMji+TqazubaU8G7PGPF+FXzTFvlye+lwwICZnMCfYLXYk9J6DzS8ksoehww UEc27agF2BtGcvfAhm0PoGWTUl7ZMY3k1fyXA3qJi8HFq29mXZi16fIMXux8a59aTVw0IERttupvh gC1A6YJxV2v90/P7ObeWXsBiK4dEoIfXwrWTjUSQnnMc7hh2CT2VX851nhr2PRMFpmxQNTnHm3msW 5HTNH3mpQ1T9RLYO2Q2QuQPTcEEBmO8NyDPxCAa9w2BtR8VbBWTeV/ScsjF/rbwZswGTiddDkDzKR MrRp0Wyg==; Received: from 54-240-197-239.amazon.com ([54.240.197.239] helo=edge-cache-150.e-ind6.amazon.com) by casper.infradead.org with esmtpsa (Exim 4.99.1 #2 (Red Hat Linux)) id 1wSeQu-00000004ZkM-2ZLr; Thu, 28 May 2026 17:22:12 +0000 Message-ID: Subject: Re: [PATCH net-next v8 3/3] gve: implement PTP gettimex64 From: David Woodhouse To: Thomas Gleixner , Harshitha Ramamurthy , netdev@vger.kernel.org Cc: joshwash@google.com, andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, richardcochran@gmail.com, jstultz@google.com, sboyd@kernel.org, willemb@google.com, nktgrg@google.com, jfraker@google.com, ziweixiao@google.com, maolson@google.com, jordanrhee@google.com, thostet@google.com, alok.a.tiwari@oracle.com, pkaligineedi@google.com, horms@kernel.org, jacob.e.keller@intel.com, yyd@google.com, jefrogers@google.com, linux-kernel@vger.kernel.org, Naman Gulati Date: Thu, 28 May 2026 18:22:11 +0100 In-Reply-To: <87mrxtwzz9.ffs@tglx> References: <20260514225842.110706-1-hramamurthy@google.com> <20260514225842.110706-4-hramamurthy@google.com> <87mrxtwzz9.ffs@tglx> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-H/JTx8OIE3J/RE1kVdNA" User-Agent: Evolution 3.52.3-0ubuntu1.1 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 --=-H/JTx8OIE3J/RE1kVdNA Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2026-05-20 at 23:08 +0200, Thomas Gleixner wrote: >=20 > But what's worse and escaped the AI scrutiny is: >=20 > =C2=A0 Your attempt to convert these 'get_cycles()' time stamps after the > =C2=A0 fact and outside of the timekeeping core protection is fundamental= ly > =C2=A0 wrong. >=20 > get_device_system_crosststamp() does >=20 > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 do { > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 seq =3D read_seqcount_begin(&tk_cor= e.seq); > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 take_timestamps(...); > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0= =C2=A0=C2=A0=C2=A0 convert_timestamps(...) > =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 } while (read_seqcount_retry(&tk_core.seq,= seq)); >=20 > which covers the whole sequence of taking the snapshots from the > hardware and the conversion. >=20 > Your abuse of this is completely out of spec. Just because it did not > blow up in your face yet does not make it in any way correct. You do not > even get bonus points for creative abuse. I'm not sure I concur. As I understand it, the requirement is that the time stamp must be after the snapshot passed in to get_device_system_crosststamp() as its 'history_begin' argument. Not that the time stamp is literally within the do{} loop you mention. That loop literally has: interval_start =3D tk->tkr_mono.cycle_last; if (!timestamp_in_interval(interval_start, now, cycles)) { ... do_interp =3D true; ...which triggers the whole adjust_historical_crosststamp() thing further down, *none* of which would have any reason to exist if what you say above is true, surely? --=-H/JTx8OIE3J/RE1kVdNA Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCD9Aw ggSOMIIDdqADAgECAhAOmiw0ECVD4cWj5DqVrT9PMA0GCSqGSIb3DQEBCwUAMGUxCzAJBgNVBAYT AlVTMRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5jb20xJDAi BgNVBAMTG0RpZ2lDZXJ0IEFzc3VyZWQgSUQgUm9vdCBDQTAeFw0yNDAxMzAwMDAwMDBaFw0zMTEx MDkyMzU5NTlaMEExCzAJBgNVBAYTAkFVMRAwDgYDVQQKEwdWZXJva2V5MSAwHgYDVQQDExdWZXJv a2V5IFNlY3VyZSBFbWFpbCBHMjCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMjvgLKj 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