What does an empty run queue entry points to?

I'm trying to figure out the technicalit开发者_运维技巧ies of scheduling in Linux. What I can't figure out is what happens with those entries in the run_queue where there are no running processes. In the run_queue we have a bitmap, a counter, and the array of lists themselves. For a list that is empty because there are no running tasks with its priority, what do the next and prev pointers point to?

If you're talking about the struct rt_prio_array structure, empty lists have next and prev pointers that point to the struct list_head in the struct rt_prio_array itself.

This is true of all the list.h lists. The list_empty() function is provided to test for this condition.