Re: [PATCH 2/2] tools/memory-model: Add write ordering by release-acquire and by locks
From: Andrea Parri
Date: Thu Jul 05 2018 - 13:07:00 EST
On Thu, Jul 05, 2018 at 09:58:48AM -0700, Paul E. McKenney wrote:
> On Thu, Jul 05, 2018 at 05:39:06PM +0200, Andrea Parri wrote:
> > > > At any rate, it looks like instead of strengthening the relation, I
> > > > should write a patch that removes it entirely. I also will add new,
> > > > stronger relations for use with locking, essentially making spin_lock
> > > > and spin_unlock be RCsc.
> > >
> > > Only in the presence of smp_mb__after_unlock_lock() or
> > > smp_mb__after_spinlock(), correct? Or am I confused about RCsc?
> > There are at least two definitions of RCsc: one as documented in the header
> > comment for smp_mb__after_spinlock() or rather in the patch under review...,
> > one as processor architects used to intend it. ;-)
> Searching isn't working for me all that well this morning, so could you
> please send me a pointer to that patch?
Sorry, I meant in _this patch_: "RCsc" as ordering everything except for
W -> R, without the barriers above (_informally, the current LKMM misses
the W -> W order only).
> Thanx, Paul