Studying how Linux boots up its radix trees...

After some validation it allocates a kmem-cache & hands off to another helper via wrappers altering the type-signature & grabbing locks.
After some additional validation & locks this other helper calls to possibly-update some state while storing some callbacks, propagates any errors or invalid states, & iterates over each CPU core.

For each CPU core it retrieves a per-core pointer & the state within, ...

1/2!