On Fri, Sep 12, 2025 at 3:39 PM Greg Kroah-Hartman
[off-list ref] wrote:

I have no objection moving this to the cdev api, BUT given that 'struct
cdev' is embedded everywhere, I don't think it's going to be a simple
task, but rather have to be done one-driver-at-a-time like the patch in
this series does it.

I don't think cdev is the right place for this as user-space keeping a
reference to a file-descriptor whose "backend" disappeared is not the
only possible problem. We can easily create a use-case of a USB I2C
expander being used by some in-kernel consumer and then unplugged.
This has nothing to do with the character device. I believe the
sub-system level is the right place for this and every driver
subsystem would have to integrate it separately, taking its various
quirks into account.

Bartosz