Re: [PATCH 4/4] UBI: Fastmap: Ensure that only one fastmap work is scheduled

[Tanya Brokhman]

On 9/30/2014 10:44 AM, Richard Weinberger wrote:
> Am 30.09.2014 09:39, schrieb Bityutskiy, Artem:
> > On Tue, 2014-09-30 at 08:59 +0200, Richard Weinberger wrote:
> > > Am 30.09.2014 08:45, schrieb Bityutskiy, Artem:
> > > > On Tue, 2014-09-30 at 00:20 +0200, Richard Weinberger wrote:
> > > > > +       spin_lock(&ubi->wl_lock);
> > > > > +       ubi->fm_work_scheduled = 0;
> > > > > +       spin_unlock(&ubi->wl_lock);
> > > >
> > > > Andrew Morton once said me that if I am protecting an integer change
> > > > like this with a spinlock, I have a problem in my locking design. He was
> > > > right for my particular case.
> > > >
> > > > Integer is changes atomic. The only other thing spinlock adds are the
> > > > barriers.
> > >
> > > I've added the spinlock to have a barrier in any case.
> >
> > Examples of any?
>
> You mean a case where the compiler would reorder code and the barrier is needed?
> I don't have one, but I'm not that creative as a modern C compiler.
> If you say that no barrier is needed I'll trust you. :-)

we just implemented the same thing :) It's being tested....
Why not use atomic_t fm_work_scheduled and save the spin_lock?

> Thanks,
> //richard
>
>
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