Re: [PATCH] Avoid time_offset overflows

2007-03-25 Thread Thomas Gleixner 
On Sun, 2007-03-25 at 01:09 -0800, Andrew Morton wrote:
> On Sat, 24 Mar 2007 06:20:45 +0100 (CET) Roman Zippel <[EMAIL PROTECTED]> 
> 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?

Here you go. It's ugly, but it should do the trick for now.

tglx

Index: linux-2.6/kernel/time/ntp.c
===
--- linux-2.6.orig/kernel/time/ntp.c
+++ linux-2.6/kernel/time/ntp.c
@@ -196,7 +196,7 @@ void __attribute__ ((weak)) notify_arch_
  */
 int do_adjtimex(struct timex *txc)
 {
-   long mtemp, save_adjust;
+   long mtemp, save_adjust, rem;
s64 freq_adj, temp64;
int result;
 
@@ -314,7 +314,9 @@ int do_adjtimex(struct timex *txc)
freq_adj += time_freq;
freq_adj = min(freq_adj, (s64)MAXFREQ_NSEC);
time_freq = max(freq_adj, (s64)-MAXFREQ_NSEC);
-   do_div(time_offset, NTP_INTERVAL_FREQ);
+   time_offset = div_long_long_rem_signed(time_offset,
+  NTP_INTERVAL_FREQ,
+  &rem);
time_offset <<= SHIFT_UPDATE;
} /* STA_PLL */
} /* txc->modes & ADJ_OFFSET */


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Re: [PATCH] Avoid time_offset overflows

2007-03-25 Thread Andrew Morton 
On Sat, 24 Mar 2007 06:20:45 +0100 (CET) Roman Zippel <[EMAIL PROTECTED]> 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?
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Re: [PATCH] Avoid time_offset overflows

2007-03-23 Thread Roman Zippel 
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).

bye, Roman
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