Re: [PATCH -next v4 1/7] x86, powerpc: fix function define in copy_mc_to_user

[Kefeng Wang <wangkefeng.wang@huawei.com>]

On 2022/5/3 9:06, Tong Tiangen wrote:
>
>
> 在 2022/5/2 22:24, Christophe Leroy 写道:
>>
>>
>> Le 20/04/2022 à 05:04, Tong Tiangen a écrit :
>>> x86/powerpc has it's implementation of copy_mc_to_user but not use 
>>> #define
>>> to declare.
>>>
>>> This may cause problems, for example, if other architectures open
>>> CONFIG_ARCH_HAS_COPY_MC, but want to use copy_mc_to_user() outside the
>>> architecture, the code add to include/linux/uaddess.h is as follows:
>>>
>>>       #ifndef copy_mc_to_user
>>>       static inline unsigned long __must_check
>>>       copy_mc_to_user(void *dst, const void *src, size_t cnt)
>>>       {
>>>         ...
>>>       }
>>>       #endif
>>>
>>> Then this definition will conflict with the implementation of 
>>> x86/powerpc
>>> and cause compilation errors as follow:
>>>
>>> Fixes: ec6347bb4339 ("x86, powerpc: Rename memcpy_mcsafe() to 
>>> copy_mc_to_{user, kernel}()")
>>
>> I don't understand, what does it fix really ? What was the
>> (existing/real) bug introduced by that patch and that your are fixing ?
>>
>> If those defined had been expected and missing, we would have had a
>> build failure. If you have one, can you describe it ?
>
It could prevent future problems when patch3 is introduced， and yes，for 
now，

this patch won't fix any issue，we could drop the fix tag, and update the 
changelog.


> There will be build failure after patch 3 is added, there is a little
> confusing for a reader of this commit in isolation.
> In the next version, I will put this patch after patch 3.
This is an alternative.
>
> Thanks,
> Tong.
> .