On Mon, Mar 27, 2023 at 02:34:02PM +0300, Matti Vaittinen wrote: > A few tests need to have a valid struct device. One such example is > tests which want to be testing devm-managed interfaces. > > Add kunit wrapper for root_device_[un]register(), which create a root > device and also add a kunit managed clean-up routine for the device > destruction upon test exit. I really do not like this as a "root device" is a horrible hack and should only be used if you have to hang other devices off of it and you don't have a real device to tie those devices to. Here you are abusing it and attempting to treat it as a real device, which it is not at all, because: > Special note: In some cases the device reference-count does not reach > zero and devm-unwinding is not done if device is not sitting on a bus. > The root_device_[un]register() are dealing with such devices and thus > this interface may not be usable by all in its current form. More > information can be found from: > https://lore.kernel.org/dri-devel/20221117165311.vovrc7usy4efiytl@houat/ See, not a real device, doesn't follow normal "struct device" rules and lifetimes, don't try to use it for a test as it will only cause problems and you will be forced to work around that in a test. Do the right thing here, create a fake bus and add devices to it. Heck, I'll even write that code if you want it, what's the requirement, something like: struct device *kunit_device_create(struct kunit *test, const char *name); void kunit_device_destroy(struct device *dev); ? Why do you want a "match" function? You don't provide documentation here for it so I have no idea. Anything else needed? > The use of root-devices in the kunit helpers is intended to be an > intermediate solution to allow tests which do not require device to sit > on a bus avoid directly abusing the root_device_[un]register() while > proper kunit device solution is being worked on. Related discussion can be > found from: > https://lore.kernel.org/lkml/CABVgOSmx3A4Vwos2_8xO-XQrQAw5gvY0nc5zLpLmcJ7FtA-dTQ@xxxxxxxxxxxxxx/ Again, no, please let's not get this wrong now and say "we will fix this later" as that's not how kernel development should work... thanks, greg k-h
