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

[Bart Van Assche]

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@xxxxxxxx/)
>
> 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 { }. BTW, my understanding is that neither the C standard nor the 
C++ standard guarantee anything about initialization of padding bytes 
nor about the initialization of unnamed bitfields for stack variables 
when using aggregate initialization.

Bart.