Re: [PATCHv4 04/11] PM: Use *_dec_not_zero instead of *_add_unless

Pavel Machek
2011-07-27T20:36:04Z

Hi!

> > atomic_dec_not_zero is defined for each architecture through
> > <linux/atomic.h> to provide the functionality of
> > atomic_add_unless(x, -1, 0).
> >
> > Signed-off-by: Sven Eckelmann <sven@narfation.org>
> > Cc: Len Brown <len.brown@intel.com>
> > Cc: Pavel Machek <pavel@ucw.cz>
> > Cc: Rafael J. Wysocki <rjw@sisk.pl>
> > Cc: linux-pm@lists.linux-foundation.org
>
> Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
>
> > ---
> > drivers/base/power/runtime.c | 4 ++--
> > include/linux/pm_runtime.h | 2 +-
> > kernel/power/hibernate.c | 4 ++--
> > kernel/power/user.c | 2 +-
> > 4 files changed, 6 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/base/power/runtime.c b/drivers/base/power/runtime.c
> > index 8dc247c..bda10d9 100644
> > --- a/drivers/base/power/runtime.c
> > +++ b/drivers/base/power/runtime.c
> > @@ -401,7 +401,7 @@ static int rpm_suspend(struct device *dev, int rpmflags)
> >
> > if (dev->parent) {
> > parent = dev->parent;
> > - atomic_add_unless(&parent->power.child_count, -1, 0);
> > + atomic_dec_not_zero(&parent->power.child_count);

I'd like to understand... Why not atomic_dec in the first place? Count
should be exact, anyway, or we run into problems, right?

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