fixup_owner — Post lock pi_state and corner case management
|u32 __user * uaddr,|
|struct futex_q * q,|
user address of the futex
futex_q (contains pi_state and access to the rt_mutex)
if the attempt to take the rt_mutex succeeded (1) or not (0)
After attempting to lock an rt_mutex, this function is called to cleanup the pi_state owner as well as handle race conditions that may allow us to acquire the lock. Must be called with the hb lock held.