Re: [PATCH] Provide an interface for getting the current tick length

[Paul Mackerras <paulus@samba.org>]

Andrew Morton writes:

> >  +	if ((time_adjust_step = time_adjust) != 0 ) {
> 
> <mutters something about coding style>

Seems perfectly plain to me, but if you don't like it I can change it.

> 
> >  +		/*
> >  +		 * Limit the amount of the step to be in the range
> >  +		 * -tickadj .. +tickadj
> >  +		 */
> >  +		time_adjust_step = min(time_adjust_step, (long)tickadj);
> >  +		time_adjust_step = max(time_adjust_step, (long)-tickadj);
> >  +	}
> >  +	delta_nsec = tick_nsec + time_adjust_step * 1000;
> 
> Is that going to overflow if sizeof(long) == 4?

No.  time_adjust_step is in microseconds and is restricted to the
range -tickadj .. tickadj, and tickadj is between 1 and 10 (assuming
HZ >= 50).  tick_nsec is around 1e9 / HZ.  There's no way delta_nsec
could end up less than 0 or larger than around 20 million for any
reasonable HZ value (i.e. >= 50).

Paul.
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