On 6/7/2022 11:20 AM, Christoph Hellwig wrote:
On Tue, Jun 07, 2022 at 12:52:49AM +0530, Kirti Wankhede wrote:
void (*remove)(struct mdev_device *dev);
- struct attribute_group **supported_type_groups;
struct device_driver driver;
};
mdev_type should be part of mdev_parent, separating it from mdev_parent
could result in more errors while using mdev framework.
Why?
Similarly it should
be added as part of mdev_register_device. Below adding types is separated
from mdev_register_device which is more error prone.
How so?
Jason has already pointed that about udev event.
What if driver
registering to mdev doesn't add mdev_types? - mdev framework is un-usable
in that case.
Yes, so it is if you don't add it to the supported_type_groups field
in the current kernel. Basic programmer error, and trivially caught.
Current kernel version mandate supported_type_groups, otherwise mdev
registration fails. But this behavior is being changed with this patch.
We had kept it together with mdev registration so that
mdev_types should be mandatory to be defined by driver during registration.
How would you mandate mdev_type by such separation?
I would not. Registering a parent without types is perfectly valid from
the code correctness perspective. It just isn't very useful. Just
like say creating a kobject without attributes in the device model.
Creating kobject without kobj_type is not allowed in the kernel,
similarly mdev registration should not be allowed without its type.
Instead of exporting mdev_type_add/mdev_type_remove, these functions
might be called internally from registration function.
Thanks,
Kirti
