From: Chris Metcalf <cmetcalf@mellanox.com>
To: Peter Zijlstra <peterz@infradead.org>,
Will Deacon <will.deacon@arm.com>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Boqun Feng <boqun.feng@gmail.com>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
vgupta@synopsys.com, rkuo@codeaurora.org, james.hogan@imgtec.com,
jejb@parisc-linux.org, davem@davemloft.net
Subject: Re: [RFC][PATCH] atomic: Fix atomic_set_release() for 'funny' architectures
Date: Fri, 9 Jun 2017 10:03:40 -0400 [thread overview]
Message-ID: <5be546b5-e34a-0bce-8cf5-b7c3f7ff28fe@mellanox.com> (raw)
In-Reply-To: <20170609110506.yod47flaav3wgoj5@hirez.programming.kicks-ass.net>
On 6/9/2017 7:05 AM, Peter Zijlstra wrote:
> Subject: atomic: Fix atomic_set_release() for 'funny' architectures
>
> Those architectures that have a special atomic_set implementation also
> need a special atomic_set_release(), because for the very same reason
> WRITE_ONCE() is broken for them, smp_store_release() is too.
>
> The vast majority is architectures that have spinlock hash based atomic
> implementation except hexagon which seems to have a hardware 'feature'.
>
> The spinlock based atomics should be SC, that is, none of them appear to
> place extra barriers in atomic_cmpxchg() or any of the other SC atomic
> primitives and therefore seem to rely on their spinlock implementation
> being SC (I did not fully validate all that).
>
> Therefore, the normal atomic_set() is SC and can be used at
> atomic_set_release().
Acked-by: Chris Metcalf <cmetcalf@mellanox.com> [for tile]
--
Chris Metcalf, Mellanox Technologies
http://www.mellanox.com
next prev parent reply other threads:[~2017-06-09 14:03 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-09 9:24 [RFC][PATCH]: documentation,atomic: Add a new atomic_t document Peter Zijlstra
2017-06-09 11:05 ` [RFC][PATCH] atomic: Fix atomic_set_release() for 'funny' architectures Peter Zijlstra
2017-06-09 11:13 ` Peter Zijlstra
2017-06-09 17:28 ` Vineet Gupta
2017-06-09 18:49 ` Peter Zijlstra
2017-06-09 18:58 ` James Bottomley
2017-06-09 14:03 ` Chris Metcalf [this message]
2017-08-10 12:10 ` [tip:locking/core] locking/atomic: " tip-bot for Peter Zijlstra
2017-06-09 15:44 ` [RFC][PATCH]: documentation,atomic: Add a new atomic_t document Will Deacon
2017-06-09 19:36 ` Peter Zijlstra
2017-06-11 13:56 ` Boqun Feng
2017-06-12 14:49 ` Peter Zijlstra
2017-06-13 6:39 ` Boqun Feng
2017-06-14 12:33 ` Will Deacon
2017-07-12 12:53 ` Boqun Feng
2017-07-12 13:08 ` Peter Zijlstra
2017-07-12 19:13 ` Paul E. McKenney
2017-07-26 11:53 ` [RFC][PATCH v3]: documentation,atomic: Add new documents Peter Zijlstra
2017-07-26 12:47 ` Boqun Feng
2017-07-31 9:05 ` Peter Zijlstra
2017-07-31 11:04 ` Boqun Feng
2017-07-31 17:43 ` Paul E. McKenney
2017-08-01 2:14 ` Boqun Feng
2017-08-01 9:01 ` Peter Zijlstra
2017-08-01 10:19 ` Will Deacon
2017-08-01 11:47 ` Peter Zijlstra
2017-08-01 12:17 ` Will Deacon
2017-08-01 12:52 ` Peter Zijlstra
2017-08-01 16:14 ` Paul E. McKenney
2017-08-01 16:42 ` Peter Zijlstra
2017-08-01 16:53 ` Will Deacon
2017-08-01 22:18 ` Paul E. McKenney
2017-08-02 8:46 ` Will Deacon
2017-08-01 18:37 ` Paul E. McKenney
2017-08-02 9:45 ` Will Deacon
2017-08-02 16:17 ` Paul E. McKenney
2017-08-03 14:05 ` Boqun Feng
2017-08-03 14:55 ` Paul E. McKenney
2017-08-03 16:12 ` Will Deacon
2017-08-03 16:58 ` Paul E. McKenney
2017-08-01 13:35 ` Paul E. McKenney
2017-07-26 16:28 ` Randy Dunlap
2017-06-09 18:15 ` [RFC][PATCH]: documentation,atomic: Add a new atomic_t document Randy Dunlap
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