# RE: \[PATCH net-next v3 1/7\] overflow: add DEFINE\_FLEX() for on-stack allocs

- From: David Laight \<hidden\>
- Date: 2023-08-18 10:50:07 
- List: netdev
- Page: https://ratatoskr.run/netdev/2023/08/11269944
- Thread: https://ratatoskr.run/netdev/2023/08/11269614/t.md

```text
From: Przemek Kitszel
> Sent: Friday, August 18, 2023 11:28 AM
...
> >>> I'm not sure you should be forcing the memset() either.
> >>
> >> This already got discussed: better to fail safe.
> >
> > Perhaps call it DEFINE_FLEX_Z() to make this clear and
> > give the option for a non-zeroing version later.
> > Not everyone wants the expense of zeroing everything.
> 
> per Kees, zeroing should be removed by compiler when not needed:
> https://lore.kernel.org/intel-wired-lan/202308101128.C4F0FA235@keescook/

Expect in the most trivial cases the compiler is pretty much never
going to remove the zeroing of the data[] part.

I'm also not at all sure what happens if there is a function
call between the initialisation and any assignments.

With a bit of effort you should be able to pass the '= {}'
through into an inner #define.
Possibly with the alternative of a caller-provider
 '= { .obj = call_supplied_initialiser }'
The 'not _Z' form would pass an empty argument.

	David

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```