Re: [PATCH -v2 1/4] Add Kconfig option ARCH_HAVE_NMI_SAFE_CMPXCHG

[Huang Ying]

On 04/08/2011 01:39 AM, Russell King - ARM Linux wrote:
> On Thu, Apr 07, 2011 at 09:29:03AM +0800, Huang Ying wrote:
>> cmpxchg() is widely used by lockless code, including NMI-safe lockless
>> code.  But on some architectures, the cmpxchg() implementation is not
>> NMI-safe, on these architectures the lockless code may need to a
>> spin_trylock_irqsave() based implementation.
>>
>> This patch adds a Kconfig option: ARCH_HAVE_NMI_SAFE_CMPXCHG, so that
>> NMI-safe lockless code can depend on it or provide different
>> implementation according to it.
>>
>> On many architectures, cmpxchg is only NMI-safe for several specific
>> operand sizes. So, ARCH_HAVE_NMI_SAFE_CMPXCHG define in this patch
>> only guarantees cmpxchg is NMI-safe for sizeof(unsigned long).
> 
> As this no longer touches any ARM code, I thinky you can drop me from the
> CC list.  Thanks.

OK.  Will do this.

Best Regards,
Huang Ying
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