Another small point:
Does your implementation support rcu_check_callbacks() with cpu !=
I don't think my locking would support it properly.
- cpu != smp_processor_id() doesn't work.
- stack space for a useless parameter.
- the explicit cpu parameter prevents the rcu code from using get_cpu_var().
What about modifying the rcu_check_callbacks() prototype? I'd propose to
remove the cpu parameter.