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From: Will Deacon <will.deacon@arm.com>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: "Boqun Feng" <boqun.feng@gmail.com>,
	"Peter Zijlstra" <peterz@infradead.org>,
	"Maciej W. Rozycki" <macro@imgtec.com>,
	"David Daney" <ddaney@caviumnetworks.com>,
	"Måns Rullgård" <mans@mansr.com>,
	"Ralf Baechle" <ralf@linux-mips.org>,
	linux-kernel@vger.kernel.org, torvalds@linux-foundation.org
Subject: Re: [RFC][PATCH] mips: Fix arch_spin_unlock()
Date: Tue, 2 Feb 2016 17:37:35 +0000	[thread overview]
Message-ID: <20160202173734.GN10166@arm.com> (raw)
In-Reply-To: <20160202171237.GL6719@linux.vnet.ibm.com>

On Tue, Feb 02, 2016 at 09:12:37AM -0800, Paul E. McKenney wrote:
> On Tue, Feb 02, 2016 at 12:20:25PM +0000, Will Deacon wrote:
> > On Tue, Feb 02, 2016 at 08:12:30PM +0800, Boqun Feng wrote:
> > > On Tue, Feb 02, 2016 at 11:45:59AM +0000, Will Deacon wrote:
> > > > Well, the following ISA2 test is permitted on ARM:
> > > > 
> > > > 
> > > > P0:
> > > > Wx=1
> > > > WyRel=1	// rcu_assign_pointer
> > > > 
> > > > P1:
> > > > Ry=1	// rcu_dereference
> > > 
> > > What if a <addr> dependency is added here? Same result?
> > 
> > Right, that fixes it. So if we're only considering things like:
> > 
> >   rcu_dereference
> >   <addr>
> >   RELEASE
> > 
> > then local transitivity should be preserved.
> 
> Whew!!!  ;-)
> 
> > I think the same applies to <ctrl>, which seems to match your later
> > example.
> 
> Could you please check?

I should've been more concrete here: it does indeed apply if you replace
the <addr> with a <ctrl> in the snippet above, I just hadn't got Boqun's
example paged in and didn't want to commit on the examples being identical.

Will

      reply	other threads:[~2016-02-02 17:37 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-11-12 12:31 [RFC][PATCH] mips: Fix arch_spin_unlock() Peter Zijlstra
2015-11-12 12:35 ` Peter Zijlstra
2015-11-12 13:31 ` Måns Rullgård
2015-11-12 14:32 ` Paul E. McKenney
2015-11-12 14:50   ` Måns Rullgård
2015-11-12 14:59     ` Paul E. McKenney
2015-11-12 17:46 ` David Daney
2015-11-12 18:00   ` Peter Zijlstra
2015-11-12 18:13   ` Måns Rullgård
2015-11-12 18:17     ` David Daney
2016-01-27  9:57       ` Maciej W. Rozycki
2016-01-27 11:43         ` Will Deacon
2016-01-27 12:41           ` Maciej W. Rozycki
2016-01-28  1:11             ` Boqun Feng
2016-01-27 14:54           ` Peter Zijlstra
2016-01-27 15:21             ` Will Deacon
2016-01-27 23:38               ` Paul E. McKenney
2016-01-28  9:57                 ` Will Deacon
2016-01-28 22:31                   ` Paul E. McKenney
2016-01-29  9:59                     ` Will Deacon
2016-01-29 10:22                       ` Paul E. McKenney
2016-02-01 13:56                         ` Will Deacon
2016-02-02  3:54                           ` Paul E. McKenney
2016-02-02  5:19                             ` Boqun Feng
2016-02-02  6:44                               ` Paul E. McKenney
2016-02-02  8:07                                 ` Linus Torvalds
2016-02-02  8:19                                   ` Linus Torvalds
2016-02-02  9:34                                     ` Boqun Feng
2016-02-02 17:30                                       ` Linus Torvalds
2016-02-02 17:51                                         ` Will Deacon
2016-02-02 18:06                                           ` Linus Torvalds
2016-02-02 19:30                                             ` Will Deacon
2016-02-02 19:55                                               ` Linus Torvalds
2016-02-03 19:13                                                 ` Will Deacon
2016-02-03  8:33                                               ` Ingo Molnar
2016-02-03 13:32                                                 ` Will Deacon
2016-02-03 19:03                                                   ` Will Deacon
2016-02-09 11:23                                                     ` Ingo Molnar
2016-02-09 11:42                                                       ` Will Deacon
2016-02-02 12:02                                     ` Paul E. McKenney
2016-02-02 17:56                                       ` Linus Torvalds
2016-02-02 22:30                                         ` Paul E. McKenney
2016-02-02 14:49                                     ` Ralf Baechle
2016-02-02 14:54                                       ` Måns Rullgård
2016-02-02 14:58                                         ` Ralf Baechle
2016-02-02 15:51                                           ` Måns Rullgård
2016-02-02 17:23                                 ` Peter Zijlstra
2016-02-02 22:38                                   ` Paul E. McKenney
2016-02-02 11:45                               ` Will Deacon
2016-02-02 12:12                                 ` Boqun Feng
2016-02-02 12:20                                   ` Will Deacon
2016-02-02 13:18                                     ` Boqun Feng
2016-02-02 17:12                                     ` Paul E. McKenney
2016-02-02 17:37                                       ` Will Deacon [this message]

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