From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966556AbcKOJSu (ORCPT ); Tue, 15 Nov 2016 04:18:50 -0500 Received: from mx2.suse.de ([195.135.220.15]:54498 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S941286AbcKOJSq (ORCPT ); Tue, 15 Nov 2016 04:18:46 -0500 Date: Tue, 15 Nov 2016 10:18:40 +0100 From: Johannes Thumshirn To: Bart Van Assche Cc: "Martin K . Petersen" , James Bottomley , Hannes Reinecke , Christoph Hellwig , Linux SCSI Mailinglist , Linux Kernel Mailinglist , Arnd Bergmann Subject: Re: [PATCH] libfc: fix seconds_since_last_reset miscalculation Message-ID: <20161115091840.7cldqui4dpi7nrz5@linux-x5ow.site> References: <1478594694-98847-1-git-send-email-jthumshirn@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 08, 2016 at 03:04:43PM +0000, Bart Van Assche wrote: [...] > Hello Johannes, > > I think the above code will miscalculate seconds_since_last_reset if > 'jiffies' wraps around after an lport has been created and before > seconds_since_last_reset is computed. Shouldn't seconds_since_last_reset > be computed as follows? > > fc_stats->seconds_since_last_reset = (jiffies - boot_time) / HZ; But what happens when jiffies - boot_time becomes negative? Then we reintroduce the bug again and have 'fcoeadm -s' show weird values. Byte, Johannes -- Johannes Thumshirn Storage jthumshirn@suse.de +49 911 74053 689 SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: Felix Imendörffer, Jane Smithard, Graham Norton HRB 21284 (AG Nürnberg) Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850