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Date:   Thu, 5 Jul 2018 19:06:36 +0200
From:   Andrea Parri <andrea.parri@amarulasolutions.com>
To:     "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc:     Alan Stern <stern@rowland.harvard.edu>,
        Will Deacon <will.deacon@arm.com>,
        LKMM Maintainers -- Akira Yokosawa <akiyks@gmail.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        David Howells <dhowells@redhat.com>,
        Jade Alglave <j.alglave@ucl.ac.uk>,
        Luc Maranget <luc.maranget@inria.fr>,
        Nicholas Piggin <npiggin@gmail.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Kernel development list <linux-kernel@vger.kernel.org>,
        dlustig@nvidia.com
Subject: Re: [PATCH 2/2] tools/memory-model: Add write ordering by
 release-acquire and by locks
Message-ID: <20180705170636.GA2380@andrea>
References: <20180704121103.GB26941@arm.com>
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 <20180705153140.GO3593@linux.vnet.ibm.com>
 <20180705153906.GA2345@andrea>
 <20180705165848.GR3593@linux.vnet.ibm.com>
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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).

  Andrea

> 
> 							Thanx, Paul
>