percpu-rwsem patches for 4.4

Hello!

This series contains performance improvements and locktorture testing for percpu-rwsem:

1. Add rtmutex torturing to locktorture, courtesy of Davidlohr Bueso.

2. Add exports to allow locktorture to be built as a module.

3. Add torture tests for percpu-rwsem.

4. Consolidate cond_resched_rcu_qs() into stutter_wait().

5. Create rcu_sync infrastructure, courtesy of Oleg Nesterov.

6. Simplify rcu_sync using new rcu_sync_ops structure, courtesy
of Oleg Nesterov.

7. Add CONFIG_PROVE_RCU checks for rcu_sync, courtesy of Oleg Nesterov.

8. Introduce rcu_sync_dtor(), courtesy of Oleg Nesterov.

9. Make percpu_free_rwsem() after kzalloc() safe, courtesy of Oleg
Nesterov.

10. Make percpu-rwsem make use of rcu_sync, courtesy of Oleg Nesterov.

11. Fix the comments outdated by rcu_sync, courtesy of Oleg Nesterov.

12. Clean up the lockdep annotations in percpu_down_read(), courtesy
Peter Zijlstra and of Oleg Nesterov.

13. Cleanup the CONFIG_PROVE_RCU checks, courtesy of Oleg Nesterov.

Thanx, Paul

------------------------------------------------------------------------

 b/Documentation/locking/locktorture.txt                       |    3 
 b/include/linux/percpu-rwsem.h                                |    3 
 b/include/linux/rcu_sync.h                                    |  168 ++++--
 b/kernel/locking/locktorture.c                                |  158 +++++
 b/kernel/locking/percpu-rwsem.c                               |   90 +--
 b/kernel/rcu/Makefile                                         |    2 
 b/kernel/rcu/rcutorture.c                                     |    2 
 b/kernel/rcu/sync.c                                           |  269 +++++++++-
 b/kernel/torture.c                                            |    1 
 b/tools/testing/selftests/rcutorture/configs/lock/CFLIST      |    4 
 b/tools/testing/selftests/rcutorture/configs/lock/LOCK05      |    6 
 b/tools/testing/selftests/rcutorture/configs/lock/LOCK05.boot |    1 
 b/tools/testing/selftests/rcutorture/configs/lock/LOCK06      |    6 
 b/tools/testing/selftests/rcutorture/configs/lock/LOCK06.boot |    1 
 14 files changed, 588 insertions(+), 126 deletions(-)