On Wed, Dec 11, 2024 at 02:45:14PM +0100, Greg KH wrote: > On Wed, Dec 11, 2024 at 02:31:07PM +0100, Danilo Krummrich wrote: > > On Wed, Dec 11, 2024 at 02:14:37PM +0100, Greg KH wrote: > > > On Wed, Dec 11, 2024 at 01:34:31PM +0100, Danilo Krummrich wrote: > > > > On Wed, Dec 11, 2024 at 01:22:33PM +0100, Danilo Krummrich wrote: > > > > > On Wed, Dec 11, 2024 at 12:05:10PM +0100, Greg KH wrote: > > > > > > On Wed, Dec 11, 2024 at 11:59:54AM +0100, Greg KH wrote: > > > > > > > On Wed, Dec 11, 2024 at 11:48:23AM +0100, Greg KH wrote: > > > > > > > > On Wed, Dec 11, 2024 at 11:45:20AM +0100, Greg KH wrote: > > > > > > > > > On Tue, Dec 10, 2024 at 11:46:28PM +0100, Danilo Krummrich wrote: > > > > > > > > > > In a subsequent patch we introduce the `Registration` abstraction used > > > > > > > > > > to register driver structures. Some subsystems require the module name on > > > > > > > > > > driver registration (e.g. PCI in __pci_register_driver()), hence pass > > > > > > > > > > the module name to `Module::init`. > > > > > > > > > > > > > > > > > > Nit, we don't need the NAME of the PCI driver (well, we do like it, but > > > > > > > > > that's not the real thing), we want the pointer to the module structure > > > > > > > > > in the register_driver call. > > > > > > > > > > > > > > > > > > Does this provide for that? I'm thinking it does, but it's not the > > > > > > > > > "name" that is the issue here. > > > > > > > > > > > > > > > > Wait, no, you really do want the name, don't you. You refer to > > > > > > > > "module.0" to get the module structure pointer (if I'm reading the code > > > > > > > > right), but as you have that pointer already, why can't you just use > > > > > > > > module->name there as well as you have a pointer to a valid module > > > > > > > > structure that has the name already embedded in it. > > > > > > > > > > > > > > In digging further, it's used by the pci code to call into lower layers, > > > > > > > but why it's using a different string other than the module name string > > > > > > > is beyond me. Looks like this goes way back before git was around, and > > > > > > > odds are it's my fault for something I wrote a long time ago. > > > > > > > > > > > > > > I'll see if I can just change the driver core to not need a name at all, > > > > > > > and pull it from the module which would make all of this go away in the > > > > > > > end. Odds are something will break but who knows... > > > > > > > > > > > > Nope, things break, the "name" is there to handle built-in modules (as > > > > > > the module pointer will be NULL.) > > > > > > > > > > > > So what you really want is not the module->name (as I don't think that > > > > > > will be set), but you want KBUILD_MODNAME which the build system sets. > > > > > > > > > > That's correct, and the reason why I pass through this name argument. > > > > > > > > > > Sorry I wasn't able to reply earlier to save you some time. > > > > > > > > > > > You shouldn't need to pass the name through all of the subsystems here, > > > > > > just rely on the build system instead. > > > > > > > > > > > > Or does the Rust side not have KBUILD_MODNAME? > > > > > > > > > > AFAIK, it doesn't (or didn't have at the time I wrote the patch). > > > > > > > > > > @Miguel: Can we access KBUILD_MODNAME conveniently? > > > > > > > > Actually, I now remember there was another reason why I pass it through in > > > > `Module::init`. > > > > > > > > Even if we had env!(KBUILD_MODNAME) already, I'd want to use it from the bus > > > > abstraction code, e.g. rust/kernel/pci.rs. But since this is generic code, it > > > > won't get the KBUILD_MODNAME from the module that is using the bus abstraction. > > > > > > Rust can't do that in a macro somehow that all pci rust drivers can pull > > > from? > > > > The problem is that register / unregister is encapsulated within methods of the > > abstraction types. So the C macro trick (while generally possible) isn't > > applicable. > > Really? You can't have something in a required "register()" type function? > Something for when the driver "instance" is created as part of > pci::Driver? You do that today in your sample driver for the id table: > const ID_TABLE: pci::IdTable<Self::IdInfo> = &PCI_TABLE; > > Something else called DRIVER_NAME that you could then set: > const DRIVER_NAME: env!(KBUILD_MODNAME); Sure, that's possible. But that means that the driver has to set it explicitly -- even when e.g. module_pci_driver! is used. In C you don't have that, because there it's implicit within the pci_register_driver() macro. (Regardless of whether it's a single module for a single driver or multiple drivers per module.) Anyways, like I mentioned, given that we have `env!(KBUILD_MODNAME)` (which we still need to add), there are other options to make it work similarly, e.g. add a parameter to `pci::Adapter` and bake this into `module_pci_driver!`. For this particular option, it would mean that for modules registering multiple drivers a corresponding name would need to be passed explicitly. > > Also, I think you will want this for when a single module registers > multiple drivers which I think can happen at times, so you could > manually override the DRIVER_NAME field. My proposal above would provide this option, but do we care? In C no one ever changes the name. There is zero users of __pci_register_driver(), everyone uses pci_register_driver() where the name is just KBUILD_MODNAME. Same for __platform_driver_register(). > > And if DRIVER_NAME doesn't get set, well, you just don't get the module > symlink in sysfs, just like what happens today if you don't provide that > field (but for PCI drivers, the .h file does it automatically for you.) > > Anyway, this is a driver issue, NOT a module issue, so having to "plumb" > the module name all the way down through this really isn't the best > abstraction to do here from what I can tell. > > thanks, > > greg k-h
