Re: [PATCH 3/8] gnttab: Remove unused-but-set variable

[Michal Orzel <michal.orzel@xxxxxxx>]

Hi Jan,

On 27.04.2022 11:59, Jan Beulich wrote:
> On 27.04.2022 11:49, Michal Orzel wrote:
>> Function unmap_common_complete defines and sets a variable ld that is
>> later on passed to a macro gnttab_host_mapping_get_page_type. On arm
>> this macro does not make use of any arguments causing a compiler to
>> warn about unused-but-set variable (when -Wunused-but-set-variable is
>> enabled). Fix this by removing ld and directly passing current->domain
>> to gnttab_host_mapping_get_page_type.
> 
> I think we want to retain the ld / rd notation. Therefore I think it's
> rather the Arm macro which wants adjusting to not leave this argument
> unused.
> 
I would agree provided that the ld variable was used in more than one place.
As it is not, it does not seem very beneficial to keep a variable that is used
just in one place and stores the macro value.

When it comes to gnttab_host_mapping_get_page_type macro, on Arm it is defined 
as (0)
so modifying it seems to be a quite big overhead.

> Jan
> 

Cheers,
Michal