Re: [GIT PULL] overlay filesystem v25

From: Al Viro
Date: Tue Oct 28 2014 - 18:55:26 EST


On Mon, Oct 27, 2014 at 09:11:27PM -0700, Paul E. McKenney wrote:
> On Tue, Oct 28, 2014 at 01:12:14AM +0000, Al Viro wrote:
> > On Mon, Oct 27, 2014 at 10:36:21AM -0700, Paul E. McKenney wrote:
> > > Code making direct use of smp_read_barrier_depends() is harder to read,
> > > in my experience, but good point on the sparse noise. Maybe a new
> > > lockless_dereference() primitive? Maybe something like the following?
> > > (Untested, probably does not even build.)
> > >
> > > #define lockless_dereference(p) \
> > > ({ \
> > > typeof(*p) *_________p1 = ACCESS_ONCE(p); \
> > > smp_read_barrier_depends(); /* Dependency order vs. p above. */ \
> > > _________p1; \
> > > })
> >
> > Hmm... Where would you prefer to put it? rcupdate.h?
>
> Good a place as any, I guess. Please see patch below. Left to myself,
> I would send this along for the next merge window, but please let me
> know if you would like it sooner.

It's needed sooner, unfortunately. Guys, could you take a look at
vfs.git#for-linus and comment?
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