Re: [RFC PATCH] checkpatch: check for function calls with struct or union on stack

[Joe Perches]

On Sat, 2018-07-28 at 08:25 +0200, Julia Lawall wrote:
> On Fri, 27 Jul 2018, Joe Perches wrote:
[]
> > It might make sense for this sort of check to be
> > added to coccinelle or maybe as a compiler warning
> > when the struct is larger than some size.
> > 
> > Original thread for Julia:
> > https://lore.kernel.org/patchwork/patch/967890/
> 
> Coccinelle doesn't directly know the size of the structure, but it can
> count the number of fields.  Maybe a case with an update in the function
> body

Perhaps this might be the most useful to check.

>  or at least 3 fields is worth reporting on?

a struct with 3 chars or bools might be faster
by value, but maybe for structs with arrays or
other structs.

For instance:

lib/vsprintf.c uses struct printf_spec which
is 16 bytes and that fits nicely in a