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

[Tong Tiangen]

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 ?

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.

Thanks,
Tong.
> > Signed-off-by: Tong Tiangen <tongtiangen@xxxxxxxxxx>
> > ---
> >    arch/powerpc/include/asm/uaccess.h | 1 +
> >    arch/x86/include/asm/uaccess.h     | 1 +
> >    2 files changed, 2 insertions(+)
> >
> > diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
> > index 9b82b38ff867..58dbe8e2e318 100644
> > --- a/arch/powerpc/include/asm/uaccess.h
> > +++ b/arch/powerpc/include/asm/uaccess.h
> > @@ -358,6 +358,7 @@ copy_mc_to_user(void __user *to, const void *from, unsigned long n)
> >    
> >    	return n;
> >    }
> > +#define copy_mc_to_user copy_mc_to_user
> >    #endif
> >    
> >    extern long __copy_from_user_flushcache(void *dst, const void __user *src,
> > diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
> > index f78e2b3501a1..e18c5f098025 100644
> > --- a/arch/x86/include/asm/uaccess.h
> > +++ b/arch/x86/include/asm/uaccess.h
> > @@ -415,6 +415,7 @@ copy_mc_to_kernel(void *to, const void *from, unsigned len);
> >    
> >    unsigned long __must_check
> >    copy_mc_to_user(void *to, const void *from, unsigned len);
> > +#define copy_mc_to_user copy_mc_to_user
> >    #endif
> >    
> >    /*