On Fri, Mar 12, 2021 at 10:23:26AM -0400, Jason Gunthorpe wrote:

This is rarely done, there should be a good reason to do it, as making
a private structure in a container_of system requires another memory
allocation.

'struct device' has this for instance, look at the 'p' member.

In this case I can't see much value

Agreed.  Moving this code to the normal kernel pattern really not just
helps to find bugs and reduce complexity, but also makes it much easier
for random kernel developers to actually be able to understand the code.