linux-kernel - Re: [RFC][PATCH v3]: documentation,atomic: Add new documents

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Message-ID: <20170801165357.GC12027@arm.com>
Date:   Tue, 1 Aug 2017 17:53:58 +0100
From:   Will Deacon <will.deacon@....com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Boqun Feng <boqun.feng@...il.com>,
        linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [RFC][PATCH v3]: documentation,atomic: Add new documents

On Tue, Aug 01, 2017 at 06:42:00PM +0200, Peter Zijlstra wrote:
> On Tue, Aug 01, 2017 at 09:14:12AM -0700, Paul E. McKenney wrote:
> > So if ARM really needs the litmus test with smp_rmb() to be allowed,
> > we need to adjust the Linux-kernel memory model appropriately.  Which
> > means that one of us needs to reach out to the usual suspects.  Would
> > you like to do that, or would you like me to?
> 
> I'm really sad ARM8.1 LSE breaks this stuff.. It is rather counter
> intuitive (then again, we _are_ talking barriers).

I can upgrade smp_rmb to smp_mb if I have to, but I still think that
code using smp_rmb() to order an operation that doesn't return a value is
weird.

Will