Description of current state

rtr_start creates a thread in

which runs, as the thread main function, rtr_fsm_start(), which more or less directly proceeds into a loop:

Improvement

We (FRR) would really like some way to run some code in the freshly created thread before anything else. This could be done either with exposing rtr_fsm_start, or having some way to pass in a function pointer that will be called at the top of the new thread.

Useful links

The reason we need this is to initialize the per-thread RCU data, otherwise it's not possible to call FRR logging functions from other rtrlib callbacks.

https://github.com/FRRouting/frr/blob/e2bf684f9a137837b9bbf21ccf6fcce55f1ff961/lib/frrcu.c#L173-L194

(rcu_thread_prepare is called before creating the thread, rcu_thread_start after/inside.)