locking/rtmutex: Another crack at spin on owner

Hi,

This is a (painfully late) followup to proposal sometime ago to add
spin on owner to rtmutexes. My first attempt was rather liberal in that
I tried avoiding the pi-dance and let the lock be stolen. However, due to
-rt constraints this series only deals with top-waiter, based on what we
do in the preempt rt patchset.

First two patches are trivial and the whole patchset as survived a week
of locktorture+pi_stress pounding at the same time without anything
breaking. That said, I'm sure it needs more testing and eyeballs, these
paths make my head hurt.

Thanks!

Davidlohr Bueso (3):
  rtmutex: Delete save_state member of struct rt_mutex
  rtmutex: Add rt_mutex_init_waiter helper
  rtmutex: Reduce top-waiter blocking on a lock

 include/linux/rtmutex.h         |  1 -
 kernel/Kconfig.locks            |  4 ++
 kernel/futex.c                  |  5 +--
 kernel/locking/rtmutex.c        | 82 +++++++++++++++++++++++++++++++++++------
 kernel/locking/rtmutex_common.h | 17 ++++++++-
 5 files changed, 92 insertions(+), 17 deletions(-)

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2.1.4