Re: [PATCH for -tip 4/4] irq: for_each_irq_desc() makes simplify

[KOSAKI Motohiro]

> Hi
> 
> >>  # define for_each_irq_desc(irq, desc)                                        \
> >>       for (irq = 0, desc = irq_to_desc(irq); irq < nr_irqs;           \
> >> -          irq++, desc = irq_to_desc(irq))
> >> +          irq++, desc = irq_to_desc(irq))                            \
> >> +             if (desc)
> >> +
> >> +
> >>  # define for_each_irq_desc_reverse(irq, desc)                                \
> >>       for (irq = nr_irqs - 1, desc = irq_to_desc(irq); irq >= 0;      \
> >> -          irq--, desc = irq_to_desc(irq))
> >> +          irq--, desc = irq_to_desc(irq))                            \
> >> +             if (desc)
> >
> > I know this has gone in, but isn't this naked 'if' unsafe.  Consider the
> > following hypothetical code:
> >
> >  if (safe)
> >    for_each_irq_desc(irq, desc) {
> >       ...
> >    }
> >  else
> >    panic();
> >
> > With the macro definition above, the loop would panic() each time !desc,
> > and _not_ panic() when !safe.  I'd consider this behaviour to be
> > unexpected, to say the least :-)
> 
> Correct.
> 
> > The fix is to change the
> >
> >  if (desc)
> >
> > in the macro to
> >
> >  if (!desc) ; else
> 
> Ok. I'll do that.
> Very thanks for good reviewing.

Done.
Thnaks Raja.

Ingo, could you please apply this patch to -tip tree?


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