[PATCH 13/17] futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()

From: Peter Zijlstra commit cfafcd117da0216520568c195cb2f6cd1980c4bb upstream. By changing futex_lock_pi() to use rt_mutex_*_proxy_lock() all wait_list modifications are done under both hb->lock and wait_lock. This closes the obvious interleave pattern between futex_lock_pi() and

[PATCH 13/17] futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock()

From: Peter Zijlstra commit cfafcd117da0216520568c195cb2f6cd1980c4bb upstream. By changing futex_lock_pi() to use rt_mutex_*_proxy_lock() all wait_list modifications are done under both hb->lock and wait_lock. This closes the obvious interleave pattern between futex_lock_pi() and