From: Alan Stern <stern@rowland.harvard.edu>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>,
<linux-kernel@vger.kernel.org>, <linux-arch@vger.kernel.org>
Subject: Re: f68f031d ("Documentation: atomic_t.txt: Explain ordering provided by smp_mb__{before,after}_atomic()")
Date: Fri, 3 May 2019 12:19:21 -0400 (EDT) [thread overview]
Message-ID: <Pine.LNX.4.44L0.1905031216310.1437-100000@iolanthe.rowland.org> (raw)
In-Reply-To: <20190503151915.GD2606@hirez.programming.kicks-ass.net>
On Fri, 3 May 2019, Peter Zijlstra wrote:
> On Fri, May 03, 2019 at 07:53:26AM -0700, Paul E. McKenney wrote:
> > Hello, Alan,
> >
> > Just following up on the -rcu commit below. I believe that it needs
> > some adjustment given Peter Zijlstra's addition of "memory" to the x86
> > non-value-returning atomics, but thought I should double-check.
>
> Right; I should get back to that thread...
The real question, still outstanding, is whether smp_mb__before_atomic
orders anything following the RMW instruction (and similarly, whether
smp_mb__after_atomic orders anything preceding the RMW instruction).
The other changes in that patch (i.e., the second and third hunks) are
okay in any case, because they just flesh out an explanation that is
already present in the text.
Alan
next prev parent reply other threads:[~2019-05-03 16:19 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-03 14:53 f68f031d ("Documentation: atomic_t.txt: Explain ordering provided by smp_mb__{before,after}_atomic()") Paul E. McKenney
2019-05-03 15:19 ` Peter Zijlstra
2019-05-03 16:19 ` Alan Stern [this message]
2019-05-03 16:34 ` Peter Zijlstra
2019-05-03 16:52 ` Alan Stern
2019-05-03 17:13 ` [PATCH v2] Documentation: atomic_t.txt: Explain ordering provided by smp_mb__{before,after}_atomic() Alan Stern
2019-05-06 16:42 ` Andrea Parri
2019-05-12 3:28 ` Paul E. McKenney
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