Re: [PATCH] sched.c

[Daniel Phillips]

On Wednesday 28 August 2002 02:41, Andreas Dilger wrote:
> On Aug 28, 2002  02:13 +0200, Daniel Phillips wrote:
> > On Tuesday 27 August 2002 20:35, Andrew Morton wrote:
> > > Lahti Oy wrote:
> > > > - for (i = 0; i < NR_CPUS; i++)
> > > > + for (i = NR_CPUS; i; i--)
> > > >    sum += cpu_rq(i)->nr_running;
> > > 
> > > Off-by-one there.  You'd want
> > > 
> > > 	for (i = NR_CPUS; --i >= 0; )
> > > 
> > > or something similarly foul ;)
> > 
> > 	int i = NR_CPUS;
> > 
> > 	while (--i)
	       ^^^ i--
> 
> Actually, I prefer the following to avoid wrap-around conditions in
> strange circumstances (i.e. if 'i' is manipulated between setting
> and the while loop):
> 
> 	while (i-- > 0) {
> 		...
> 	}

Hi Andreas,

If this counter goes negative you have other, much bigger problems
and you better not try to cover them up.

Daniel