Re: 2.5.40-mm2

[Andrew Morton]

Robert Love wrote:
> 
> On Sun, 2002-10-06 at 18:07, Andrew Morton wrote:
> 
> > > -                       while (base->running_timer == timer) {
> > > +                       while (base->running_timer == timer)
> > >                                 cpu_relax();
> > > -                               preempt_disable();
> > > -                               preempt_enable();
> 
> I am confused as to why Ingo would put these here.  He knows very well
> what he is doing... surely he had a reason.
> 
> If he intended to force a preemption point here, then the lines needs to
> be reversed.  This assumes, of course, preemption is disabled here.  But
> I do not think it is.
> 
> If he just wanted to check for preemption, we have a
> preempt_check_resched() which does just that (I even think he wrote
> it).  Note as long as interrupts are enabled this probably does not
> achieve much anyhow.
> 

I think it's a way of doing "cond_resched() if cond_resched() is
a legal thing to do right now".

I'm sure David isn't using preempt though.