From: Peter Zijlstra <peterz@infradead.org>
To: Davidlohr Bueso <dave@stgolabs.net>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Oleg Nesterov <oleg@redhat.com>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
mtk.manpages@gmail.com, dvhart@infradead.org,
Vineet.Gupta1@synopsys.com, ralf@linux-mips.org,
ddaney@caviumnetworks.com, Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org
Subject: Re: futex atomic vs ordering constraints
Date: Tue, 1 Sep 2015 18:38:12 +0200 [thread overview]
Message-ID: <20150901163812.GN16853@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1440811986.1831.9.camel@stgolabs.net>
On Fri, Aug 28, 2015 at 06:33:06PM -0700, Davidlohr Bueso wrote:
> On Wed, 2015-08-26 at 20:16 +0200, Peter Zijlstra wrote:
> > Of course, if anything else prior to futex_atomic_op_inuser() implies an
> > (RCsc) RELEASE or stronger the primitive can do without providing
> > anything itself.
> >
> > This turns out to be the case, a successful get_futex_key() implies a
> > full memory barrier; recent: 1d0dcb3ad9d3 ("futex: Implement lockless
> > wakeups").
>
> Hmm while it is certainly true that get_futex_key() implies a full
> barrier, I don't see why you're referring to the recent wake_q stuff;
D'oh, because I'm a sheep or so. I meant:
b0c29f79ecea (futexes: Avoid taking the hb->lock if there's nothing to wake up)
next prev parent reply other threads:[~2015-09-01 16:38 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-08-26 18:16 Peter Zijlstra
2015-08-29 1:33 ` Davidlohr Bueso
2015-09-01 16:38 ` Peter Zijlstra [this message]
2015-09-01 16:31 ` Will Deacon
2015-09-01 16:42 ` Peter Zijlstra
2015-09-01 16:47 ` Will Deacon
2015-09-01 19:05 ` Thomas Gleixner
2015-09-02 12:55 ` Peter Zijlstra
2015-09-02 16:10 ` Chris Metcalf
2015-09-02 17:00 ` Peter Zijlstra
2015-09-02 17:25 ` Chris Metcalf
2015-09-02 21:18 ` Linus Torvalds
2015-09-04 17:25 ` Chris Metcalf
2015-09-05 17:53 ` Peter Zijlstra
2015-09-07 9:30 ` Will Deacon
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