linux-kernel - Re: Control dependency between prior load in while condition and later store?

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Message-ID: <20180405145650.GT4043@hirez.programming.kicks-ass.net>
Date:   Thu, 5 Apr 2018 16:56:50 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Alan Stern <stern@...land.harvard.edu>
Cc:     Daniel Jordan <daniel.m.jordan@...cle.com>, parri.andrea@...il.com,
        will.deacon@....com, boqun.feng@...il.com, npiggin@...il.com,
        dhowells@...hat.com, j.alglave@....ac.uk, luc.maranget@...ia.fr,
        paulmck@...ux.vnet.ibm.com, akiyks@...il.com,
        linux-kernel@...r.kernel.org,
        Steven Sistare <steven.sistare@...cle.com>,
        Pasha Tatashin <pasha.tatashin@...cle.com>
Subject: Re: Control dependency between prior load in while condition and
 later store?

On Thu, Apr 05, 2018 at 10:35:22AM -0400, Alan Stern wrote:
> In this example, READ_ONCE() is in fact a volatile access, so we're 
> okay.

But our documentation clearly states a control-dep can only be from a
READ_ONCE() (or something stronger), right? So we should be good
irrespectively.