From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 5 Sep 2002 17:23:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 5 Sep 2002 17:23:09 -0400 Received: from h24-67-14-151.cg.shawcable.net ([24.67.14.151]:54011 "EHLO webber.adilger.int") by vger.kernel.org with ESMTP id ; Thu, 5 Sep 2002 17:23:08 -0400 From: Andreas Dilger Date: Thu, 5 Sep 2002 15:25:16 -0600 To: "Richard B. Johnson" Cc: Peter Surda , linux-kernel@vger.kernel.org Subject: Re: Uptime timer-wrap Message-ID: <20020905212516.GN7887@clusterfs.com> Mail-Followup-To: "Richard B. Johnson" , Peter Surda , linux-kernel@vger.kernel.org References: <20020905180253.GC2567@noir.cb.ac.at> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4i X-GPG-Key: 1024D/0D35BED6 X-GPG-Fingerprint: 7A37 5D79 BF1B CECA D44F 8A29 A488 39F5 0D35 BED6 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sep 05, 2002 16:16 -0400, Richard B. Johnson wrote: > I tried to simulate your observation by making a driver that > set the 'jiffies' count upon an 'open'. The idea was to get > the jiffies count to something close to wrap so I didn't have to > wait a long time. > > Anyway, I found that setting the jiffies count to more than a > few hundred counts into the future, causes the machine to halt > with no interrupts (no Capslock, no NumLock, no network ping, etc). > > The machine just stops and I don't understand why. > > > spin_lock_irqsave(&xlock, flags); > jiffies += 0x1000; > spin_lock_irqrestore(&xlock, flags); > > ... works just fine, but, changing 0x1000 to 0x7fffffff causes > the machine to stop as reported. > > Does anybody have a clue? Yes, because now some kernel code is going to wait 147 days - 1s or something like that to finish. See Tim Schmielau patch for testing jiffies wrap. It _initializes_ jiffies to a high pre-wrap value, maybe 5 minutes before wrap, instead of playing around with the jiffies value after the system is running. Cheers, Andreas -- Andreas Dilger http://www-mddsp.enel.ucalgary.ca/People/adilger/ http://sourceforge.net/projects/ext2resize/