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

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Date:   Sun, 24 Apr 2022 09:16:05 +0800
From:   Tong Tiangen <tongtiangen@...wei.com>
To:     Michael Ellerman <mpe@...erman.id.au>,
        Mark Rutland <mark.rutland@....com>,
        James Morse <james.morse@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Ingo Molnar" <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Robin Murphy <robin.murphy@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "Catalin Marinas" <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        "Alexander Viro" <viro@...iv.linux.org.uk>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>, <x86@...nel.org>,
        "H . Peter Anvin" <hpa@...or.com>
CC:     <linuxppc-dev@...ts.ozlabs.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        Kefeng Wang <wangkefeng.wang@...wei.com>,
        Xie XiuQi <xiexiuqi@...wei.com>,
        Guohanjun <guohanjun@...wei.com>
Subject: Re: [PATCH -next v4 1/7] x86, powerpc: fix function define in
 copy_mc_to_user



在 2022/4/22 17:45, Michael Ellerman 写道:
> Tong Tiangen <tongtiangen@...wei.com> writes:
>> 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
>       
> The above doesn't exist yet, you add it in patch 3, which is a little
> confusing for a reader of this commit in isolation.
> 
> I think you could safely move that into this patch, and then this patch
> would be ~= "Add generic fallback version of copy_mc_to_user()".
> 
> It's probably not worth doing a whole new version of the series just for
> that, but if you need to do a new version for some other reason I think
> it would be cleaner to introduce the fallback in this commit.
> 

Agreed, will do in next version.

Thanks,
Tong.

>> 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}()")
>> Signed-off-by: Tong Tiangen <tongtiangen@...wei.com>
>> ---
>>   arch/powerpc/include/asm/uaccess.h | 1 +
> 
> Acked-by: Michael Ellerman <mpe@...erman.id.au> (powerpc)
> 
> cheers
> .