how to iterate through all tasks on a specific run queue?

[nad gam]

I would like create a system call that iterate over all tasks in a
specific run queue .
the signature would be "iterateTasks(int cpu_x)",
which means - iterate over tasks in run queue belong to cpu number x .

 how do I do that?
I saw someone suggestion doing so from init_task with
"list_for_each_safe" macro, though Im not sure how to access init_task
of a specific cpu ?

Thanks