Re: [PATCH tip/core/rcu 21/21] drivers/vhost: Remove now-redundant read_barrier_depends()

[Peter Zijlstra]

On Tue, Dec 05, 2017 at 08:31:20PM +0200, Michael S. Tsirkin wrote:

> Apropos, READ_ONCE is now asymmetrical with WRITE_ONCE.
> 
> I can read a pointer with READ_ONCE and be sure the value
> is sane, but only if I also remember to put in smp_wmb before
> WRITE_ONCE. Otherwise the pointer is ok but no guarantees
> about the data pointed to.

That was already the case on everything except Alpha. And the canonical
match do the data dependency is store_release, not wmb.