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From: Luben Tuikov <luben@splentec.com>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, axboe@suse.de
Subject: Re: [PATCH]: jiffies wrap in ll_rw_blk.c
Date: Wed, 20 Nov 2002 16:00:44 -0500	[thread overview]
Message-ID: <3DDBF7FC.B0DBC75D@splentec.com> (raw)
In-Reply-To: 1037827173.3267.78.camel@irongate.swansea.linux.org.uk

Alan Cox wrote:
> 
> On Wed, 2002-11-20 at 20:44, Luben Tuikov wrote:
> > --- ll_rw_blk.c.old     Wed Nov 20 15:32:50 2002
> > +++ ll_rw_blk.c Wed Nov 20 15:33:06 2002
> > @@ -2092,7 +2092,7 @@
> >                 complete(req->waiting);
> >
> >         if (disk) {
> > -               unsigned long duration = jiffies - req->start_time;
> > +               unsigned long duration = (signed) jiffies - (signed) req->start_time;
> >                 switch (rq_data_dir(req)) {
> 
> It was right before. Your patch breaks it. Think about it in unsigned
> maths
> 
>               0x00000002 - 0xFFFFFFFF = 0x00000003

0x2 - (-0x1) = 0x2 + 0x1 = 0x3

Right! I thought (signed) does the job. I actually tried
it both ways and works all right. I guess either way works fine.

-- 
Luben

  reply	other threads:[~2002-11-20 20:53 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-11-20 20:44 [PATCH]: jiffies wrap in ll_rw_blk.c Luben Tuikov
2002-11-20 21:06 ` Benjamin LaHaise
2002-11-20 21:18   ` Luben Tuikov
2002-11-20 21:19 ` Alan Cox
2002-11-20 21:00   ` Luben Tuikov [this message]
2002-11-20 21:31     ` Alan Cox
2002-11-20 21:15       ` Luben Tuikov
2002-11-20 22:20   ` Olivier Galibert

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