Re: [PATCH 3/4] x86/kvm: Resolve shadow warnings in macro expansion

[Paolo Bonzini <pbonzini@redhat.com>]

Il 25/07/2014 15:27, Jeff Kirsher ha scritto:
> From: Mark Rustad <mark.d.rustad@intel.com>
> 
> Resolve shadow warnings that appear in W=2 builds. In this case,
> a macro declared an inner local variable with the same name as an
> outer one. This can be a serious hazard in the event that the outer
> variable is ever passed as a parameter, as the inner variable will
> be referenced instead of what was intended. This macro doesn't have
> any parameters - at this time - but prepend an _ to all of the
> macro-declared variables as is the custom, to resolve the warnings
> and eliminate any future hazard.
> 
> Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> ---
>  arch/x86/kvm/mmutrace.h | 24 ++++++++++++------------
>  1 file changed, 12 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/x86/kvm/mmutrace.h b/arch/x86/kvm/mmutrace.h
> index 9d2e0ff..2d8d00c 100644
> --- a/arch/x86/kvm/mmutrace.h
> +++ b/arch/x86/kvm/mmutrace.h
> @@ -22,26 +22,26 @@
>  	__entry->unsync = sp->unsync;
>  
>  #define KVM_MMU_PAGE_PRINTK() ({				        \
> -	const char *ret = p->buffer + p->len;				\
> -	static const char *access_str[] = {			        \
> +	const char *_ret = p->buffer + p->len;				\
> +	static const char *_access_str[] = {			        \
>  		"---", "--x", "w--", "w-x", "-u-", "-ux", "wu-", "wux"  \
>  	};							        \
> -	union kvm_mmu_page_role role;				        \
> +	union kvm_mmu_page_role _role;				        \
>  								        \
> -	role.word = __entry->role;					\
> +	_role.word = __entry->role;					\
>  									\
>  	trace_seq_printf(p, "sp gen %lx gfn %llx %u%s q%u%s %s%s"	\
>  			 " %snxe root %u %s%c",	__entry->mmu_valid_gen,	\
> -			 __entry->gfn, role.level,			\
> -			 role.cr4_pae ? " pae" : "",			\
> -			 role.quadrant,					\
> -			 role.direct ? " direct" : "",			\
> -			 access_str[role.access],			\
> -			 role.invalid ? " invalid" : "",		\
> -			 role.nxe ? "" : "!",				\
> +			 __entry->gfn, _role.level,			\
> +			 _role.cr4_pae ? " pae" : "",			\
> +			 _role.quadrant,				\
> +			 _role.direct ? " direct" : "",			\
> +			 _access_str[_role.access],			\
> +			 _role.invalid ? " invalid" : "",		\
> +			 _role.nxe ? "" : "!",				\
>  			 __entry->root_count,				\
>  			 __entry->unsync ? "unsync" : "sync", 0);	\
> -	ret;								\
> +	_ret;								\
>  		})
>  
>  #define kvm_mmu_trace_pferr_flags       \
> 

I think this unnecessarily uglifies the code, so I am not applying it.
Gleb, what do you think?

Paolo