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

[Hammond, John]

> 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.

This is someone's attempt to avoid the unused variable warnings which would occur
in some places when LINVRNT(exp) is defined as ((void)0).