On Mon, Jun 07, 2021 at 11:23:22AM +0200, Greg Kroah-Hartman wrote:
> On Mon, Jun 07, 2021 at 11:33:17AM +0300, Dan Carpenter wrote:
> > Greg asked about struct holes and the answer is "= {}" will zero out
> > struct holes but it's not important in this case. The "= {}" is a GCC
> > extension for zeroing structs and it's not part of the C standard.
> > The struct has a kernel pointer in it so we had better not be shairing
> > it to user space.
>
> I thought we proved that "= {}" will _NOT_ zero out holes in structures.
> Or did we really prove that? I can't remember now, do you?
>
Assigning a struct to a struct will not initialize the struct holes.
struct foo foo = *p;
We worried about = {} and people looked at the C standard. The
standard is not clear. But then people said that = {} is a GCC
extension and will initialize the struct holes.
The other thing is that in GCC they had intended "= {0};" to work
exactly the same as "= {};" and initialize the holes but there was a
version which had a bug and didn't. :P
regards,
dan carpenter
