[PATCHv5] atomic: add *_dec_not_zero

[Benjamin Herrenschmidt]

On Mon, 2011-12-05 at 08:57 +0100, Sven Eckelmann wrote:
> On Monday 05 December 2011 09:41:55 Benjamin Herrenschmidt wrote:
> > On Sun, 2011-12-04 at 22:18 +0000, Russell King - ARM Linux wrote:
> > 
> >  .../...
> > 
> > > And really, I believe it would be a good cleanup if all the standard
> > > definitions for atomic64 ops (like atomic64_add_negative) were also
> > > defined in include/linux/atomic.h rather than individually in every
> > > atomic*.h header throughout the kernel source, except where an arch
> > > wants to explicitly override it.  Yet again, virtually all architectures
> > > define these in exactly the same way.
> > > 
> > > We have more than enough code in arch/ for any architecture to worry
> > > about, we don't need schemes to add more when there's simple and
> > > practical solutions to avoiding doing so if the right design were
> > > chosen (preferably from the outset.)
> > > 
> > > So, I'm not going to offer my ack for a change which I don't believe
> > > is the correct approach.
> > 
> > I agree with Russell, his approach is a lot easier to maintain long run,
> > we should even consider converting existing definitions.
> 
> I would rather go with "the existing definitions have to converted" and this 
> means "not by this patch".

Right. I didn't suggest -you- had to do it as a pre-req to your patch.

>  At the moment, the atomic64 stuff exist only as 
> separate generic or arch specific implementation. It is fine that Russell King 
> noticed that people like Arun Sharma did a lot of work to made it true for 
> atomic_t, but atomic64_t is a little bit different right now (at least as I 
> understand it).

Cheers,
Ben.