On 6/25/25 11:05, Christian Brauner wrote: > On Tue, Jun 24, 2025 at 11:02:16AM +0200, Christian Brauner wrote: > I don't understand that argument. I don't care if out-of-tree users > abuse some symbol because: > > * If they ever show up with a complaint we'll tell them to go away. > * If they want to be merged upstream, we'll tell them to either change > the code in question to not rely on the offending symbol or we decide > that it's ok for them to use it and allow-list them. > > I do however very much care about in-tree consumers even for non-GPLd > symbols. I want anyone who tries to use a symbol that we decided > requires substantial arguments to be used to come to us and justify it. > So EXPORT_*_FOR_MODULES() would certainly help with that. > > The other things is that using EXPORT_SYMBOL() or even > EXPORT_SYMBOL_GPL() sends the wrong message to other module-like > wanna-be consumers of these functions. I'm specifically thinking about > bpf. They more than once argued that anything exposed to modules can > also be exposed as a bpf kfunc as the stability guarantees are > comparable. > > And it is not an insane argument. Being able to use > EXPOR_SYMBOL_FOR_MODULES() would also allow to communicate "Hey, this > very much just exists for the purpose of this one-off consumer that > really can't do without it or without some other ugly hack.". > > Because this is where the pain for us is: If you do large-scale > refactorings (/me glares at Al, Christoph, and in the mirror) the worst > case is finding out that some special-purpose helper has grown N new > users with a bunch of them using it completely wrong and now having to > massage core code to not break something that's technically inherently > broken. > > Out-of-tree consumers have zero relevance for all of this. For all I > care they don't exist. It's about the maintainers ability to chop off > the Kraken's tentacles. Then I think you can just use EXPORT_SYMBOL_GPL_FOR_MODULES() as it is today. It's intended for a particular in-tree module, which is by definition going to be GPL. I doubt anyone will come complaining that you've cut off their ability to fake the name of the in-tree module while having non-GPL license. So I don't really see the danger of causing holy license wars there. The _FOR_MODULES() part is restricting enough even without _GPL_. But if we can indeed enforce in-tree-ness and drop _GPL_ from the name, it would be cleaner IMHO.
