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From: Waiman Long <waiman.long@hp.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>,
	linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
	paulmck@linux.vnet.ibm.com
Subject: Re: [PATCH v2 7/7] ARM: atomics: define our SMP atomics in terms of _relaxed operations
Date: Thu, 16 Jul 2015 20:00:34 -0400	[thread overview]
Message-ID: <55A845A2.20507@hp.com> (raw)
In-Reply-To: <20150716210821.GC19282@twins.programming.kicks-ass.net>

On 07/16/2015 05:08 PM, Peter Zijlstra wrote:
> On Thu, Jul 16, 2015 at 04:40:03PM -0400, Waiman Long wrote:
>> On 07/16/2015 11:32 AM, Will Deacon wrote:
>>> @@ -117,6 +115,8 @@ static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size
>>>   #error "SMP is not supported on this platform"
>               ^^^^^^^^^^^^^

That #error is only for ARMv5 or below.

>>>   #endif
>>>
>>> +#define xchg xchg_relaxed
>> Is that a typo? I think xchg() needs to be a full memory barrier.
> Pointless on UP.

  parent reply	other threads:[~2015-07-17  0:00 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-16 15:32 [PATCH v2 0/7] Add generic support for relaxed atomics Will Deacon
2015-07-16 15:32 ` Will Deacon
2015-07-16 15:32 ` [PATCH v2 1/7] atomics: add acquire/release/relaxed variants of some atomic operations Will Deacon
2015-07-16 15:32   ` Will Deacon
2015-07-17  0:07   ` Waiman Long
2015-07-17  9:40     ` Will Deacon
2015-07-17 17:19       ` Waiman Long
2015-07-17 17:19         ` Waiman Long
2015-07-17 17:30         ` Will Deacon
2015-07-16 15:32 ` [PATCH v2 2/7] asm-generic: rework atomic-long.h to avoid bulk code duplication Will Deacon
2015-07-16 15:32   ` Will Deacon
2015-07-16 15:32 ` [PATCH v2 3/7] asm-generic: add relaxed/acquire/release variants for atomic_long_t Will Deacon
2015-07-16 15:32   ` Will Deacon
2015-07-16 15:32 ` [PATCH v2 4/7] lockref: remove homebrew cmpxchg64_relaxed macro definition Will Deacon
2015-07-16 15:32   ` Will Deacon
2015-07-16 16:48   ` Peter Zijlstra
2015-07-16 17:00     ` Will Deacon
2015-07-16 15:32 ` [PATCH v2 5/7] locking/qrwlock: make use of acquire/release/relaxed atomics Will Deacon
2015-07-16 15:32   ` Will Deacon
2015-07-16 16:59   ` Peter Zijlstra
2015-07-16 18:13     ` Will Deacon
2015-07-16 18:13       ` Will Deacon
2015-07-16 15:32 ` [PATCH v2 6/7] include/llist: use linux/atomic.h instead of asm/cmpxchg.h Will Deacon
2015-07-16 15:32   ` Will Deacon
2015-07-16 15:32 ` [PATCH v2 7/7] ARM: atomics: define our SMP atomics in terms of _relaxed operations Will Deacon
2015-07-16 15:32   ` Will Deacon
2015-07-16 20:40   ` Waiman Long
2015-07-16 21:08     ` Peter Zijlstra
2015-07-16 21:08       ` Peter Zijlstra
2015-07-17  0:00       ` Waiman Long [this message]
2015-07-17  9:35         ` Will Deacon
2015-07-17  9:35           ` Will Deacon
2015-07-17 17:17           ` Waiman Long
2015-07-17 17:17             ` Waiman Long

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