From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755613AbXKNNKn (ORCPT ); Wed, 14 Nov 2007 08:10:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752150AbXKNNKg (ORCPT ); Wed, 14 Nov 2007 08:10:36 -0500 Received: from mho-02-bos.mailhop.org ([63.208.196.179]:51065 "EHLO mho-02-bos.mailhop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751386AbXKNNKf (ORCPT ); Wed, 14 Nov 2007 08:10:35 -0500 X-Mail-Handler: MailHop Outbound by DynDNS X-Originating-IP: 209.94.135.27 X-Report-Abuse-To: abuse@dyndns.com (see http://www.mailhop.org/outbound/abuse.html for abuse reporting information) X-MHO-User: U2FsdGVkX18UZQTxzM5w484h6FNjJtgh Message-ID: <473AF3BE.1010006@reed.com> Date: Wed, 14 Nov 2007 08:10:22 -0500 From: "David P. Reed" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.8.1.5) Gecko/20070727 Fedora/2.0.0.5-2.fc7 Thunderbird/2.0.0.5 Mnenhy/0.7.5.0 MIME-Version: 1.0 To: Thomas Gleixner CC: linux-kernel@vger.kernel.org, Allessandro Zummo Subject: Re: [PATCH] x86: fix locking and sync bugs in x86_64 RTC code in time_64.c References: <466F0941.9060201@reed.com> <1181682498.8176.224.camel@chaos> <469578CD.3080609@reed.com> <1184216528.12353.203.camel@chaos> <1184218962.12353.209.camel@chaos> <46964352.7040301@reed.com> <1184253339.12353.223.camel@chaos> <469697C6.50903@reed.com> <1184274754.12353.254.camel@chaos> <47388586.7010509@reed.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Will make two patches and resend. Thomas Gleixner wrote: > David, > > On Mon, 12 Nov 2007, David P. Reed wrote: > > >> From: David P. Reed >> >> Fix two bugs in arch/x86/kernel/time_64.c that affect the x86_64 kernel. 1) a >> repeatable hard freeze due to interrupts when the ntpd service calls >> update_persistent_clock(), 2) potentially unstable PC RTC timer values when >> timer is read. >> > > 1) Please send separate patches for separate problems. > > 2) Your patch is white space damaged and does not apply. Please run it > through scripts/checkpatch.pl before submitting, maybe send it to > yourself first and verify that it applies correctly. > > >> Signed-off-by: David P. Reed >> --- >> More explanation: >> 1) A repeatable but randomly timed freeze has been happening in Fedora 6 and 7 >> for the last year, whenever I run the ntpd service on my AMD64x2 HP Pavilion >> dv9000z laptop. This freeze is due to the use of spin_lock(&rtc_lock) under >> the assumption (per a bad comment) that set_rtc_mmss is called only with >> interrupts disabled. The call from ntp.c to update_persistent_clock is made >> with interrupts enabled. >> > > Good catch. > > >> 2) the use of an incorrect technique for reading the standard PC RTC timer, >> which is documented to "disconnect" time registers from the bus while updates >> are in progress. The use of UIP flag while interrupts are disabled to protect >> a 244 microsecond window is one of the Motorola spec sheet's documented ways >> to read the RTC time registers reliably. I realize that not all "clones" of >> the >> > > of the what ? > > Also put the detailed description into the patch comment, please. > > >> The patch updates the misleading comments and minimizes the amount of time >> that the kernel disables interrupts. >> >> I have thoroughly tested this patch on a number of x86_64 machines with >> various numbers of cores and chipsets, using 2.6.24rc2 kernel source. Note >> that while testing the ntp code I found another bug in kernel/time/ntp.c which >> is independent of this fix - neither patch requires the other. >> >> If possible, I'd love to see the patch merged with 2.6.24, and even with >> 2.6.23. >> > > Care to resend ? > > Thanks, > > tglx > >