Re: [PATCH v2 08/10] drivers/auxdisplay: add a KFuzzTest for parse_xy()

[Lukas Wunner <lukas@wunner.de>]

On Sat, Sep 20, 2025 at 02:08:01PM +0200, Alexander Potapenko wrote:
> On Sat, Sep 20, 2025 at 12:54 PM Andy Shevchenko <andy.shevchenko@gmail.com> wrote:
> > On Fri, Sep 19, 2025 at 5:58 PM Ethan Graham <ethan.w.s.graham@gmail.com> wrote:
> > > +++ b/drivers/auxdisplay/charlcd.c
> > > @@ -682,3 +682,11 @@ EXPORT_SYMBOL_GPL(charlcd_unregister);
> > >
> > >  MODULE_DESCRIPTION("Character LCD core support");
> > >  MODULE_LICENSE("GPL");
> > > +
> > > +/*
> > > + * When CONFIG_KFUZZTEST is enabled, we include this _kfuzz.c file to ensure
> > > + * that KFuzzTest targets are built.
> > > + */
> > > +#ifdef CONFIG_KFUZZTEST
> > > +#include "tests/charlcd_kfuzz.c"
> > > +#endif /* CONFIG_KFUZZTEST */
> >
> > No, NAK. We don't want to see these in each and every module. Please,
> > make sure that nothing, except maybe Kconfig, is modified in this
> > folder (yet, you may add a _separate_ test module, as you already have
> > done in this patch).
> 
> This is one of the cases in which we can't go without changing the
> original code, because parse_xy() is a static function.
> Including the test into the source is not the only option, we could as
> well make the function visible unconditionally, or introduce a macro
> similar to VISIBLE_IF_KUNIT.
> Do you prefer any of those?

Just add something like this to drivers/auxdisplay/Makefile:

ifeq ($(CONFIG_KFUZZTEST),y)
CFLAGS_charlcd.o := -include $(src)/tests/charlcd_kfuzz.c
endif

Alternatively, if the file in tests/ always has the same name
as the source file but with "_kfuzz.c" suffix, consider amending
scripts/Makefile.build to always include the "_kfuzz.c" file
if it exists and CONFIG_KFUZZTEST=y, thus avoiding the need
to amend all the individual Makefiles in the tree.

Thanks,

Lukas