netdev - Re: rcu_read_lock lost its compiler barrier

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Date:   Wed, 5 Jun 2019 23:05:11 -0700
From:   "Paul E. McKenney" <paulmck@...ux.ibm.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     Alan Stern <stern@...land.harvard.edu>,
        Boqun Feng <boqun.feng@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Fengguang Wu <fengguang.wu@...el.com>, LKP <lkp@...org>,
        LKML <linux-kernel@...r.kernel.org>,
        Netdev <netdev@...r.kernel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Andrea Parri <andrea.parri@...rulasolutions.com>,
        Luc Maranget <luc.maranget@...ia.fr>,
        Jade Alglave <j.alglave@....ac.uk>
Subject: Re: rcu_read_lock lost its compiler barrier

On Thu, Jun 06, 2019 at 12:51:09PM +0800, Herbert Xu wrote:
> On Tue, Jun 04, 2019 at 10:44:18AM -0400, Alan Stern wrote:
> >
> > Currently the LKMM says the test is allowed and there is a data race, 
> > but this answer clearly is wrong since it would violate the RCU 
> > guarantee.
> 
> Thank you! This is what I tried to say all along in this thread
> but you expressed it in a much better way :)

In case you were wondering, the reason that I was giving you such
a hard time was that from what I could see, you were pushing for no
{READ,WRITE}_ONCE() at all.  ;-)

							Thanx, Paul