Re: [v3,11/41] mips: reuse asm-generic/barrier.h

From: Peter Zijlstra
Date: Fri Jan 15 2016 - 16:29:53 EST


On Fri, Jan 15, 2016 at 09:39:12AM -0800, Paul E. McKenney wrote:
> Should we start putting litmus tests for the various examples
> somewhere, perhaps in a litmus-tests directory within each participating
> architecture? I have a pile of powerpc-related litmus tests on my laptop,
> but they probably aren't doing all that much good there.

Yeah, or a version of them in C that we can 'compile'?
>
> commit 2cb4e83a1b5c89c8e39b8a64bd89269d05913e41
> Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
> Date: Fri Jan 15 09:30:42 2016 -0800
>
> documentation: Distinguish between local and global transitivity
>
> The introduction of smp_load_acquire() and smp_store_release() had
> the side effect of introducing a weaker notion of transitivity:
> The transitivity of full smp_mb() barriers is global, but that
> of smp_store_release()/smp_load_acquire() chains is local. This
> commit therefore introduces the notion of local transitivity and
> gives an example.
>
> Reported-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Reported-by: Will Deacon <will.deacon@xxxxxxx>
> Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>

I think it fails to mention smp_mb__after_release_acquire(), although I
suspect we didn't actually introduce the primitive yet, which raises the
point, do we want to?