Re: drivers/block/rbd.c: atomic_inc_return_safe() & atomic_dec_return_safe()

[Shuah Khan]

On 10/2/20 5:44 PM, Jens Axboe wrote:
> On 10/2/20 4:34 PM, Shuah Khan wrote:
> > All,
> >
> > I came across these atomic_inc_return_safe() & atomic_dec_return_safe()
> > functions that hold the counters at safe values.
> >
> > atomic_inc_return_safe()
> >
> > If the counter is already 0 it will not be incremented.
> > If the counter is already at its maximum value returns
> > -EINVAL without updating it.
> >
> > atomic_dec_return_safe()
> >
> > Decrement the counter.  Return the resulting value, or -EINVAL
> >
> > These two routines are static and only used in rbd.c.
> >
> > Can these become part of atomic_t ops?
>
> I think you just want to use refcount_t for this use case. They
> have safe guards for under/overflow.

Makes sense. Guess these came before refcount_t.

I will track this for refcount_t conversion.

thanks,
-- Shuah