Re: [PATCH -v3 3/8] locking: Introduce smp_acquire__after_ctrl_dep

From: Peter Zijlstra
Date: Wed Jun 01 2016 - 12:23:17 EST


On Wed, Jun 01, 2016 at 09:52:14PM +0800, Boqun Feng wrote:
> On Tue, May 31, 2016 at 11:41:37AM +0200, Peter Zijlstra wrote:

> > @@ -292,7 +282,7 @@ static void sem_wait_array(struct sem_ar
> > sem = sma->sem_base + i;
> > spin_unlock_wait(&sem->lock);
> > }
> > - ipc_smp_acquire__after_spin_is_unlocked();
> > + smp_acquire__after_ctrl_dep();
>
> I wonder whether we can kill this barrier after updating
> spin_unlock_wait() to ACQUIRE?

See patch 5 doing that :-)