From: Waiman Long <waiman.long@hp.com>
To: Will Deacon <will.deacon@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"paulmck@linux.vnet.ibm.com" <paulmck@linux.vnet.ibm.com>
Subject: Re: [PATCH v2 7/7] ARM: atomics: define our SMP atomics in terms of _relaxed operations
Date: Fri, 17 Jul 2015 13:17:10 -0400 [thread overview]
Message-ID: <55A93896.3090905@hp.com> (raw)
In-Reply-To: <20150717093555.GC18994@arm.com>
On 07/17/2015 05:35 AM, Will Deacon wrote:
> On Fri, Jul 17, 2015 at 01:00:34AM +0100, Waiman Long wrote:
>> 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.
> I don't see the problem here. As Peter pointed out, this code only gets
> looked at if !SMP and structuring it this way means I can have one
> definition of xchg_relaxed, regardless of architecture version.
>
> Will
I am sorry that I got confused as to where it is defined. It should be
OK in this case.
Cheers,
Longman
prev parent reply other threads:[~2015-07-17 17:17 UTC|newest]
Thread overview: 21+ 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 ` [PATCH v2 1/7] atomics: add acquire/release/relaxed variants of some atomic operations 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 17:30 ` 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 ` [PATCH v2 3/7] asm-generic: add relaxed/acquire/release variants for atomic_long_t Will Deacon
2015-07-16 15:32 ` [PATCH v2 4/7] lockref: remove homebrew cmpxchg64_relaxed macro definition 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 16:59 ` Peter Zijlstra
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 ` [PATCH v2 7/7] ARM: atomics: define our SMP atomics in terms of _relaxed operations Will Deacon
2015-07-16 20:40 ` Waiman Long
2015-07-16 21:08 ` Peter Zijlstra
2015-07-17 0:00 ` Waiman Long
2015-07-17 9:35 ` Will Deacon
2015-07-17 17:17 ` Waiman Long [this message]
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