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:   Tue, 26 Jun 2018 22:15:03 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc:     linux-kernel@vger.kernel.org, mingo@kernel.org,
        jiangshanlai@gmail.com, dipankar@in.ibm.com,
        akpm@linux-foundation.org, mathieu.desnoyers@efficios.com,
        josh@joshtriplett.org, tglx@linutronix.de, rostedt@goodmis.org,
        dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com,
        oleg@redhat.com, joel@joelfernandes.org
Subject: Re: [PATCH tip/core/rcu 16/27] rcu: Add comment documenting how
 rcu_seq_snap works
Message-ID: <20180626201503.GS2494@hirez.programming.kicks-ass.net>
References: <20180626003448.GA26209@linux.vnet.ibm.com>
 <20180626003513.27812-16-paulmck@linux.vnet.ibm.com>
 <20180626171454.GI2494@hirez.programming.kicks-ass.net>
 <20180626180855.GE3593@linux.vnet.ibm.com>
 <20180626192113.GM2494@hirez.programming.kicks-ass.net>
 <20180626193146.GK3593@linux.vnet.ibm.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20180626193146.GK3593@linux.vnet.ibm.com>
User-Agent: Mutt/1.10.0 (2018-05-17)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Jun 26, 2018 at 12:31:46PM -0700, Paul E. McKenney wrote:
> > Then the existing comment is misleading and really needs change.
> 
> Would it be sufficient to add something like "The memory barrier is
> required to support the many-to-many ordering guaranteed by RCU grace
> periods"?

What would lead me to wonder why after the load and not (also) before.