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

Bart Van Assche
2021-07-28T21:37:29Z

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 { }. 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.