Re: [PATCH] drivers/staging/lustre: Coding-guideline: Missing a blank line after declarations

Pushkar Jambhlekar
2017-04-04T10:05:37Z

((void)sizeof !!(exp)) => I believe it is for compiler to unflag
"unused variable" warning.

On Tue, Apr 4, 2017 at 3:08 PM, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> On Tue, Apr 04, 2017 at 02:45:26PM +0530, Pushkar Jambhlekar wrote:
>> diff --git a/drivers/staging/lustre/lustre/obdclass/cl_page.c b/drivers/staging/lustre/lustre/obdclass/cl_page.c
>> index cd9a40c..71fcc4c 100644
>> --- a/drivers/staging/lustre/lustre/obdclass/cl_page.c
>> +++ b/drivers/staging/lustre/lustre/obdclass/cl_page.c
>> @@ -482,6 +482,7 @@ void cl_page_disown0(const struct lu_env *env,
>> int cl_page_is_owned(const struct cl_page *pg, const struct cl_io *io)
>> {
>> struct cl_io *top = cl_io_top((struct cl_io *)io);
>> +
>> LINVRNT(cl_object_same(pg->cp_obj, io->ci_obj));
>> return pg->cp_state == CPS_OWNED && pg->cp_owner == top;
>> }
>
> This is not related to the patch but I don't understand CLOBINVRNT() and
> LINVRNT().
>
> # define LINVRNT(exp) LASSERT(exp)
> # define LINVRNT(exp) ((void)sizeof !!(exp))
>
> Why do we do the sizeof() instead of just an empty define? The compiler
> calculates the size at compile time and doesn't execute the expression
> so it's the same as an empty define so far as I can tell.
>
> regards,
> dan carpenter

--
Jambhlekar Pushkar Arun