Re: [PATCH 10/17] tty: remove MODULE_LICENSE in non-modules

[Greg Kroah-Hartman]

On Thu, Mar 09, 2023 at 02:38:10PM -0800, Luis Chamberlain wrote:
> On Thu, Mar 09, 2023 at 05:15:42PM +0100, Greg Kroah-Hartman wrote:
> > On Thu, Mar 02, 2023 at 09:17:52PM +0000, Nick Alcock wrote:
> > > Since commit 8b41fc4454e ("kbuild: create modules.builtin without
> > > Makefile.modbuiltin or tristate.conf"), MODULE_LICENSE declarations
> > > are used to identify modules. As a consequence, uses of the macro
> > > in non-modules will cause modprobe to misidentify their containing
> > > object file as a module when it is not (false positives), and modprobe
> > > might succeed rather than failing with a suitable error message.
> > > 
> > > So remove it in the files in this commit, none of which can be built as
> > > modules.
> > > 
> > > Signed-off-by: Nick Alcock <nick.alcock@xxxxxxxxxx>
> > > Suggested-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
> > > Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx>
> > > Cc: linux-modules@xxxxxxxxxxxxxxx
> > > Cc: linux-kernel@xxxxxxxxxxxxxxx
> > > Cc: Hitomi Hasegawa <hasegawa-hitomi@xxxxxxxxxxx>
> > > Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > > Cc: Jiri Slaby <jirislaby@xxxxxxxxxx>
> > > ---
> > >  drivers/tty/n_null.c | 1 -
> > >  1 file changed, 1 deletion(-)
> > > 
> > > diff --git a/drivers/tty/n_null.c b/drivers/tty/n_null.c
> > > index f913b665af725..c24f75942c49d 100644
> > > --- a/drivers/tty/n_null.c
> > > +++ b/drivers/tty/n_null.c
> > > @@ -63,7 +63,6 @@ static void __exit n_null_exit(void)
> > >  module_init(n_null_init);
> > >  module_exit(n_null_exit);
> > >  
> > > -MODULE_LICENSE("GPL");
> > >  MODULE_AUTHOR("Alan Cox");
> > >  MODULE_ALIAS_LDISC(N_NULL);
> > >  MODULE_DESCRIPTION("Null ldisc driver");
> > > -- 
> > > 2.39.1.268.g9de2f9a303
> > > 
> > 
> > Nope, sorry, this is not good to do, please fix kbuild instead of
> > forcing a tree-wide change like this.
> 
> Masahiro Yamada already NACK'd it such effort:
> 
> https://lkml.kernel.org/r/CAK7LNAQLttPD=Ae==e0CYeQtS78=o_JZFK+zxa29JnUYio52Ug@xxxxxxxxxxxxxx
> 
> And his descriptiuon of the reasoning and logic is explained here:              
> 
> https://lore.kernel.org/all/CAK7LNASL7_RgfASstBvN6AzhR=nMU=HsQvODf5q13Xud8tBWRQ@xxxxxxxxxxxxxx/
> 
> Let me summarize it though with a few quotes from him:
> 
> "Having false-positives in modules.builtin should be OK"
> "In this sense, having always-builtin entries in module.builtin is OK."

None of that matters, sorry.

Again, all I am saying is that you can not have some MODULE_() macros
that are ok for code that is built in, and some that are not, for
"reasons" that have to do how you all are treating the build system
infrastructure as you are now putting arbritrary requirements for all
driver authors (of which there are thousands) to know this.

Just change the macros to work properly in both cases, I can't believe
this is all that hard as obviously all of the other macros work both
ways, right?  That should not require any kbuild changes.

> The reason Nick wants to do this work is that his future patches
> (which have been under review for years and I'm starting to chew on
> it and provide guidance on now) extend our ability to have more
> elaborate symbol to address mapping with more metdata, which does
> include information such as if something came from a module. So
> long term *I* certainly am interested in a deterministic way to
> determine if something could be a module.
> 
> For a more elaborate attempt on my part to try to describe the problem
> and some side ideas I had if we wanted an alternative:
> 
> https://lore.kernel.org/all/Y/kXDqW+7d71C4wz@xxxxxxxxxxxxxxxxxxxxxx/
> 
> I should also mention Christoph has also suggested we eventually move
> towards automatically generating the module license tag from the SPDX
> tag:
> 
> https://lore.kernel.org/all/Y5BNCbFyvNA1Xp%2FX@xxxxxxxxxxxxx

That too would be wonderful, and I would love to see that, but it does
not remove the base problem here that you are somehow forcing all driver
authors to change their code for the build system changes which should
not be affecting them at all at this point in time.

If you all do trigger off of the SPDX tags, then the removal of all
MODULE_LICENSE() instances would be great too, but I don't think you are
there yet (and it also wouldn't require removal all at once as you could
just stub out that macro to be nothing.)  But this is not the real issue
here...

Maybe the solution is to stop triggering on MODULE_LICENSE() as
something magic for the build, as obviously that is the root problem
here.  Or something else, I don't know, but what you all are doing here
does not seem correct at all, sorry, and is only going to cause more
long-term problems with maintenance and headaches for driver authors.

thanks,

greg k-h