Re: [PATCH 01/64] media: omap3isp: Extract struct group for memcpy() region

Greg Kroah-Hartman
2021-07-29T05:56:36Z

On Wed, Jul 28, 2021 at 11:37:30PM +0200, David Sterba wrote:
> On Wed, Jul 28, 2021 at 02:37:20PM -0700, Bart Van Assche wrote:
> > On 7/28/21 2:14 AM, Dan Carpenter wrote:
> > > On Wed, Jul 28, 2021 at 10:59:22AM +0200, David Sterba wrote:
> > >>> drivers/media/platform/omap3isp/ispstat.c | 5 +--
> > >>> include/uapi/linux/omap3isp.h | 44 +++++++++++++++++------
> > >>> 2 files changed, 36 insertions(+), 13 deletions(-)
> > >>>
> > >>> diff --git a/drivers/media/platform/omap3isp/ispstat.c b/drivers/media/platform/omap3isp/ispstat.c
> > >>> index 5b9b57f4d9bf..ea8222fed38e 100644
> > >>> --- a/drivers/media/platform/omap3isp/ispstat.c
> > >>> +++ b/drivers/media/platform/omap3isp/ispstat.c
> > >>> @@ -512,7 +512,7 @@ int omap3isp_stat_request_statistics(struct ispstat *stat,
> > >>> int omap3isp_stat_request_statistics_time32(struct ispstat *stat,
> > >>> struct omap3isp_stat_data_time32 *data)
> > >>> {
> > >>> - struct omap3isp_stat_data data64;
> > >>> + struct omap3isp_stat_data data64 = { };
> > >>
> > >> Should this be { 0 } ?
> > >>
> > >> We've seen patches trying to switch from { 0 } to { } but the answer
> > >> was that { 0 } is supposed to be used,
> > >> http://www.ex-parrot.com/~chris/random/initialise.html
> > >>
> > >> (from https://lore.kernel.org/lkml/fbddb15a-6e46-3f21-23ba-b18f66e3448a@suse.com/)
> > >
> > > In the kernel we don't care about portability so much. Use the = { }
> > > GCC extension. If the first member of the struct is a pointer then
> > > Sparse will complain about = { 0 }.
> >
> > +1 for { }.
>
> Oh, I thought the tendency is is to use { 0 } because that can also
> intialize the compound members, by a "scalar 0" as it appears in the
> code.
>

Holes in the structure might not be initialized to anything if you do
either one of these as well.

Or did we finally prove that is not the case? I can not remember
anymore...

greg k-h