From: Will Deacon <will.deacon@arm.com>
To: Daniel Lustig <dlustig@nvidia.com>
Cc: paulmck@linux.vnet.ibm.com,
Alan Stern <stern@rowland.harvard.edu>,
Andrea Parri <andrea.parri@amarulasolutions.com>,
LKMM Maintainers -- Akira Yokosawa <akiyks@gmail.com>,
Boqun Feng <boqun.feng@gmail.com>,
David Howells <dhowells@redhat.com>,
Jade Alglave <j.alglave@ucl.ac.uk>,
Luc Maranget <luc.maranget@inria.fr>,
Nicholas Piggin <npiggin@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Kernel development list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 2/2] tools/memory-model: Add write ordering by release-acquire and by locks
Date: Thu, 5 Jul 2018 17:22:26 +0100 [thread overview]
Message-ID: <20180705162225.GH14470@arm.com> (raw)
In-Reply-To: <b41849a8-76cd-2375-dd80-c1bdeb9ea7d2@nvidia.com>
On Thu, Jul 05, 2018 at 08:44:39AM -0700, Daniel Lustig wrote:
> On 7/5/2018 8:31 AM, Paul E. McKenney wrote:
> > On Thu, Jul 05, 2018 at 10:21:36AM -0400, Alan Stern wrote:
> >> At any rate, it looks like instead of strengthening the relation, I
> >> should write a patch that removes it entirely. I also will add new,
> >> stronger relations for use with locking, essentially making spin_lock
> >> and spin_unlock be RCsc.
> >
> > Only in the presence of smp_mb__after_unlock_lock() or
> > smp_mb__after_spinlock(), correct? Or am I confused about RCsc?
> >
> > Thanx, Paul
> >
>
> In terms of naming...is what you're asking for really RCsc? To me,
> that would imply that even stores in the first critical section would
> need to be ordered before loads in the second critical section.
> Meaning that even x86 would need an mfence in either lock() or unlock()?
I think a LOCK operation always implies an atomic RmW, which will give
full ordering guarantees on x86. I know there have been interesting issues
involving I/O accesses in the past, but I think that's still out of scope
for the memory model.
Peter will know.
Will
next prev parent reply other threads:[~2018-07-05 16:21 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-21 17:27 [PATCH 2/2] tools/memory-model: Add write ordering by release-acquire and by locks Alan Stern
2018-06-21 18:04 ` Peter Zijlstra
2018-06-22 3:34 ` Paul E. McKenney
2018-06-22 8:08 ` Peter Zijlstra
2018-06-22 8:09 ` Will Deacon
2018-06-22 9:55 ` Will Deacon
2018-06-22 10:31 ` Peter Zijlstra
2018-06-22 10:38 ` Will Deacon
2018-06-22 11:25 ` Andrea Parri
2018-06-22 16:40 ` Paul E. McKenney
2018-06-22 18:09 ` Alan Stern
2018-06-22 18:30 ` Will Deacon
2018-06-22 19:11 ` Alan Stern
2018-06-22 20:53 ` Paul E. McKenney
2018-07-04 11:53 ` Will Deacon
2018-06-25 8:19 ` Andrea Parri
2018-07-03 17:28 ` Alan Stern
2018-07-04 11:28 ` Paul E. McKenney
2018-07-04 12:13 ` Will Deacon
2018-07-05 14:23 ` Alan Stern
2018-07-05 15:31 ` Paul E. McKenney
2018-07-04 12:11 ` Will Deacon
2018-07-05 14:00 ` Andrea Parri
2018-07-05 14:44 ` Will Deacon
2018-07-05 15:16 ` Daniel Lustig
2018-07-05 15:35 ` Daniel Lustig
2018-07-05 14:21 ` Alan Stern
2018-07-05 14:46 ` Will Deacon
2018-07-05 14:57 ` Alan Stern
2018-07-05 15:15 ` Will Deacon
2018-07-05 15:09 ` Andrea Parri
2018-07-06 20:37 ` Alan Stern
2018-07-06 21:10 ` Paul E. McKenney
2018-07-09 16:52 ` Will Deacon
2018-07-09 17:29 ` Daniel Lustig
2018-07-09 19:18 ` Alan Stern
2018-07-05 15:31 ` Paul E. McKenney
2018-07-05 15:39 ` Andrea Parri
2018-07-05 16:58 ` Paul E. McKenney
2018-07-05 17:06 ` Andrea Parri
2018-07-05 15:44 ` Daniel Lustig
2018-07-05 16:22 ` Will Deacon [this message]
2018-07-05 16:56 ` Paul E. McKenney
2018-07-05 18:12 ` Daniel Lustig
2018-07-05 18:38 ` Andrea Parri
2018-07-05 18:44 ` Andrea Parri
2018-07-05 23:32 ` Paul E. McKenney
2018-07-05 23:31 ` Paul E. McKenney
2018-07-06 9:25 ` Will Deacon
2018-07-06 14:14 ` Paul E. McKenney
2018-06-25 7:32 ` Peter Zijlstra
2018-06-25 8:29 ` Andrea Parri
2018-06-25 9:06 ` Peter Zijlstra
2018-06-22 9:06 ` Andrea Parri
2018-06-22 19:23 ` Alan Stern
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