From: Peter Zijlstra <peterz@infradead.org>
To: David Daney <ddaney@caviumnetworks.com>
Cc: ralf@linux-mips.org, linux-kernel@vger.kernel.org,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Will Deacon <will.deacon@arm.com>,
torvalds@linux-foundation.org, boqun.feng@gmail.com
Subject: Re: [RFC][PATCH] mips: Fix arch_spin_unlock()
Date: Thu, 12 Nov 2015 19:00:03 +0100 [thread overview]
Message-ID: <20151112180003.GE17308@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <5644D08D.4080206@caviumnetworks.com>
On Thu, Nov 12, 2015 at 09:46:53AM -0800, David Daney wrote:
> For CONFIG_CPU_CAVIUM_OCTEON the proper thing would be:
>
> smp_wmb();
> smp_rmb();
>
> Which expands to exactly the same thing as wmb() because smp_rmb() expands
> to nothing.
OK, so the current code isn't broken because for Cavium wmb is suffient
because rmb is a no-op, and for !Cavium wmb expands to SYNC.
> You yourself seem to have added smp_store_release(), so we could even do:
>
> smp_store_release(&lock->h.serving_now, lock->h.serving_now + 1);
>
> That would leave us to cook up a proper definition of smp_store_release().
That is indeed the better solution.
next prev parent reply other threads:[~2015-11-12 18:00 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-12 12:31 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 [this message]
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
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