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From: Andrew Morton <akpm@linux-foundation.org>
To: Roman Zippel <zippel@linux-m68k.org>
Cc: john stultz <johnstul@us.ibm.com>, Ingo Molnar <mingo@elte.hu>,
	Thomas Gleixner <tglx@linutronix.de>,
	lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Avoid time_offset overflows
Date: Sun, 25 Mar 2007 01:09:03 -0800	[thread overview]
Message-ID: <20070325010903.a0e6e624.akpm@linux-foundation.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0703240153220.14457@scrub.home>

On Sat, 24 Mar 2007 06:20:45 +0100 (CET) Roman Zippel <zippel@linux-m68k.org> wrote:

> Hi,
> 
> On Fri, 23 Mar 2007, john stultz wrote:
> 
> > @@ -314,8 +314,8 @@ #endif
> >  		    freq_adj += time_freq;
> >  		    freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
> >  		    time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
> > -		    time_offset = (time_offset / NTP_INTERVAL_FREQ)
> > -		    			<< SHIFT_UPDATE;
> > +		    do_div(time_offset, NTP_INTERVAL_FREQ);
> > +		    time_offset <<= SHIFT_UPDATE;
> >  		} /* STA_PLL */
> >  	    } /* txc->modes & ADJ_OFFSET */
> >  	    if (txc->modes & ADJ_TICK)
> 
> This is wrong, time_offset is signed and do_div is unsigned.
> In general I planned to do the same change, but the do_div API could use a 
> little cleanup to provide some clear function for signed/unsigned divide 
> (hopefully with a better name than div_long_long_rem_signed or 
> do_div_llr).
> 

Can we do a minimal thing for 2.6.21, worry about API beautification later?

  reply	other threads:[~2007-03-25  9:10 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-03-24  0:40 john stultz
2007-03-24  5:20 ` Roman Zippel
2007-03-25  9:09   ` Andrew Morton [this message]
2007-03-25 11:07     ` Thomas Gleixner
2007-03-25 11:14       ` [patch] ntp: avoid integer overflow in do_adjtimex() Ingo Molnar
2007-03-25 13:01         ` Thomas Gleixner

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