From: "H. Peter Anvin" <hpa@zytor.com>
To: Christoph Lameter <cl@linux.com>
Cc: Tejun Heo <tj@kernel.org>,
akpm@linux-foundation.org, Pekka Enberg <penberg@cs.helsinki.fi>,
linux-kernel@vger.kernel.org,
Eric Dumazet <eric.dumazet@gmail.com>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [cpuops cmpxchg double V1 2/4] x86: this_cpu_cmpxchg_double() support
Date: Wed, 15 Dec 2010 08:32:40 -0800 [thread overview]
Message-ID: <4D08EDA8.90702@zytor.com> (raw)
In-Reply-To: <alpine.DEB.2.00.1012151011550.12186@router.home>
On 12/15/2010 08:12 AM, Christoph Lameter wrote:
> On Tue, 14 Dec 2010, H. Peter Anvin wrote:
>
>>> NAK on this. This is acceptable for cmpxchg8b only because we don't
>>> support SMP on 486s anymore. x86-64 is another matter...
>>>
>>
>> Hm, this is meant to be a CPU local operation, isn't it... it isn't very
>> clear from the comments or naming *in this file*.
>
> Ok. But the code is correct as far as I can tell. Its not a global cmpxchg
> but local. Interrupt disable is ok.
>
>> Could you make it a little clearer in the local code, please?
>
> ok.
>
Yes, that's what I meant... the code is correct, it's just not obvious
from someone who looks at the code that it is correct, because the
intended function of the code isn't obvious from that file by itself (in
fact, it looks almost exactly like the 486 cmpxchg ersatz code.)
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2010-12-15 16:33 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-14 17:48 [cpuops cmpxchg double V1 0/4] this_cpu_cmpxchg_double support Christoph Lameter
2010-12-14 17:48 ` [cpuops cmpxchg double V1 1/4] Generic support for this_cpu_cmpxchg_double Christoph Lameter
2010-12-18 14:47 ` Tejun Heo
2010-12-18 14:51 ` Tejun Heo
2010-12-21 22:36 ` Christoph Lameter
2010-12-21 23:24 ` H. Peter Anvin
2010-12-22 9:14 ` Tejun Heo
2010-12-24 0:16 ` Christoph Lameter
2010-12-24 0:22 ` H. Peter Anvin
2010-12-25 4:53 ` Christoph Lameter
2010-12-25 6:11 ` H. Peter Anvin
2010-12-25 16:52 ` Tejun Heo
2010-12-25 23:55 ` Christoph Lameter
2010-12-27 10:52 ` Tejun Heo
2011-01-03 22:43 ` Christoph Lameter
2010-12-14 17:48 ` [cpuops cmpxchg double V1 2/4] x86: this_cpu_cmpxchg_double() support Christoph Lameter
2010-12-15 0:46 ` H. Peter Anvin
2010-12-15 0:56 ` H. Peter Anvin
2010-12-15 16:12 ` Christoph Lameter
2010-12-15 16:20 ` Christoph Lameter
2010-12-15 17:36 ` H. Peter Anvin
2010-12-15 17:53 ` Christoph Lameter
2010-12-15 16:32 ` H. Peter Anvin [this message]
2010-12-15 16:41 ` Christoph Lameter
2010-12-14 17:48 ` [cpuops cmpxchg double V1 3/4] slub: Get rid of slab_free_hook_irq() Christoph Lameter
2010-12-14 17:48 ` [cpuops cmpxchg double V1 4/4] Lockless (and preemptless) fastpaths for slub Christoph Lameter
2010-12-15 16:51 ` Tejun Heo
2010-12-15 16:55 ` Pekka Enberg
2010-12-15 16:57 ` Tejun Heo
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