Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 28 Nov 2018 21:45:23 +0100
From:   Andrea Parri <andrea.parri@amarulasolutions.com>
To:     David Howells <dhowells@redhat.com>
Cc:     "Paul E. McKenney" <paulmck@linux.ibm.com>,
        gregkh@linux-foundation.org,
        Kiran Kumar Modukuri <kiran.modukuri@gmail.com>,
        viro@zeniv.linux.org.uk, sandeen@redhat.com,
        linux-cachefs@redhat.com, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/4] fscache: Fix race in fscache_op_complete() due to
 split atomic_sub & read
Message-ID: <20181128204522.GA3183@andrea>
References: <20181126165606.GA11282@andrea>
 <20181017164848.GA9795@andrea>
 <20181017151134.GA8966@andrea>
 <153978619457.8478.3813964117489247515.stgit@warthog.procyon.org.uk>
 <153978621809.8478.2198040871218302573.stgit@warthog.procyon.org.uk>
 <14408.1539790333@warthog.procyon.org.uk>
 <26942.1543249596@warthog.procyon.org.uk>
 <4283.1543416204@warthog.procyon.org.uk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <4283.1543416204@warthog.procyon.org.uk>
User-Agent: Mutt/1.9.4 (2018-02-28)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

> > Sure.  My point was: those operations are currently not atomic _and_
> > they provide no ordering; I think that the above commit message does
> > a good work in explaining *why* we need atomicity, but can't say the
> > same for the memory-ordering requirement.
> 
> Having discussed it with Paul McKenney and thought about it some more, I think
> relaxed is probably okay since there isn't a pair of variables that need
> ordering.

Count several troubled, and exiting!, weekends spent "processing" (my)
conversations with Paul...  so been there! ;-)

Makes all sense to me of course, thank you for the clarification.

  Andrea


> 
> David