RE: Fix unlock_buffer() to work the same way as bit_unlock()

From: Boehm, Hans
Date: Thu Mar 30 2006 - 17:23:58 EST


> From: Christoph Lameter
> On Thu, 30 Mar 2006, Nick Piggin wrote:
>
> > Zoltan Menyhart wrote:
> >
> > > However, I do not think your implementation would be
> efficient due
> > > to selecting the ordering mode at run time:
> > >
> > > > + switch (mode) {
> > > > + case MODE_NONE :
> > > > + case MODE_ACQUIRE :
> > > > + return cmpxchg_acq(m, old, new);
> > > > + case MODE_FENCE :
> > > > + smp_mb();
> > > > + /* Fall through */
> > > > + case MODE_RELEASE :
> > > > + return cmpxchg_rel(m, old, new);
> > >
> >
> > BTW. Isn't MODE_FENCE wrong? Seems like a read or write
> could be moved
> > above cmpxchg_rel?
>
> Hmmm.... We should call this MODE_BARRIER I guess...
>
I arrived at the conclusion that "fence" is a better term, at least in
user-level code. "Barrier" seems to generate confusion with
"pthread_barrier_wait" and similar constructs, which are a different
kind of beast.

Hans
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