On Mon, Mar 27, 2023 at 03:20:06PM +0300, Matti Vaittinen wrote:
On 3/27/23 15:01, Greg Kroah-Hartman wrote:
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.
Ok. I understood using the root-device has been a work-around in some other tests. Thus continuing use it for tests where we don't need the bus until we have a proper alternative was suggested by David.
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);
Thanks for the offer Greg. This, however, is being already worked on by David. I don't want to step on his toes by writing the same thing, nor do I think I should be pushing him to rush on his work.
Ok, David, my offer stands, if you want me to write this I will be glad to do so.
thanks,
greg k-h