From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 2.6.11-rc2 11/29] ide: add ide_drive_t.sleeping Date: Fri, 04 Feb 2005 07:20:14 +0900 Message-ID: <4202A39E.8020004@home-tj.org> References: <20050202024017.GA621@htj.dyndns.org> <20050202025448.GL621@htj.dyndns.org> <58cb370e05020216476a8f403c@mail.gmail.com> <20050203113710.GV5710@suse.de> <58cb370e05020305304e5d504@mail.gmail.com> <20050203133228.GA2816@suse.de> <58cb370e05020305354cbb16ee@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit In-Reply-To: <58cb370e05020305354cbb16ee@mail.gmail.com> Sender: linux-kernel-owner@vger.kernel.org To: Bartlomiej Zolnierkiewicz Cc: Jens Axboe , linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org List-Id: linux-ide@vger.kernel.org Bartlomiej Zolnierkiewicz wrote: > On Thu, 3 Feb 2005 14:32:29 +0100, Jens Axboe wrote: > >>On Thu, Feb 03 2005, Bartlomiej Zolnierkiewicz wrote: >> >>>On Thu, 3 Feb 2005 12:37:10 +0100, Jens Axboe wrote: >>> >>>>On Thu, Feb 03 2005, Bartlomiej Zolnierkiewicz wrote: >>>> >>>>>On Wed, 2 Feb 2005 11:54:48 +0900, Tejun Heo wrote: >>>>> >>>>>>>11_ide_drive_sleeping_fix.patch >>>>>>> >>>>>>> ide_drive_t.sleeping field added. 0 in sleep field used to >>>>>>> indicate inactive sleeping but because 0 is a valid jiffy >>>>>>> value, though slim, there's a chance that something can go >>>>>>> weird. And while at it, explicit jiffy comparisons are >>>>>>> converted to use time_{after|before} macros. >>>>> >>>>>Same question as for "add ide_hwgroup_t.polling" patch. >>>>>AFAICS drive->sleep is either '0' or 'timeout + jiffies' (always > 0) >>>> >>>>Hmm, what if jiffies + timeout == 0? >>> >>>Hm, jiffies is unsigned and timeout is always > 0 >>>but this is still possible if jiffies + timeout wraps, right? >> >>Precisely, if jiffies is exactly 'timeout' away from wrapping to 0 it >>could happen. So I think the fix looks sane. > > > agreed Actually, jiffies is initialized to INITIAL_JIFFIES which is defined in such a way that it overflows after 5 min after boot to help finding bugs related to jiffies wrap. So, the chance of something weird happening in the bugs fixed in patches 11 and 12 isn't that exteremely slim. :-) -- tejun