Additional RCU-consolidation cleanups for v4.20/v5.0

Hello!

This series contains yet more cleanups for RCU flavor consolidation:

1. Inline the now-trivial increment_cpu_stall_ticks() into its sole
caller.

2. Pull the rcu_gp_kthread() function's force-quiescent-state loop
into a separate function

3. Consolidate RCU-bh update-side function definitions, putting
them all in one place at the end of rcupdate.h.

4. Consolidate RCU-sched update-side function definitions, putting
them all in one place at the end of rcupdate.h.

5. Add RCU-bh and RCU-sched support for extended readers, so that
rcutorture will mix and match all RCU read-side primitives.

6. Stop testing RCU-bh and RCU-sched.

7-8. Remove the "rcu_bh" and "sched" torture types.

9. Remove now-unused rcutorture APIs.

10-21. Clean up flavor-related definitions and comments.

22. Remove !PREEMPT code from rcu_note_voluntary_context_switch(),
since it now has meaning only in PREEMPT kernels.

23. Define rcu_all_qs() only in !PREEMPT builds, since that is
now the only place it is used.

24. Inline _rcu_barrier() into its sole remaining caller.

Thanx, Paul

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

 Documentation/admin-guide/kernel-parameters.txt            |    6 
 include/linux/rculist.h                                    |   32 -
 include/linux/rcupdate.h                                   |  100 ++-
 include/linux/rcupdate_wait.h                              |   14 
 include/linux/rcutiny.h                                    |   47 -
 include/linux/rcutree.h                                    |   28 
 include/trace/events/rcu.h                                 |   20 
 kernel/rcu/Kconfig                                         |   20 
 kernel/rcu/rcu.h                                           |   28 
 kernel/rcu/rcuperf.c                                       |   65 --
 kernel/rcu/rcutorture.c                                    |  125 ---
 kernel/rcu/srcutree.c                                      |    2 
 kernel/rcu/tiny.c                                          |   10 
 kernel/rcu/tree.c                                          |  414 +++----------
 kernel/rcu/tree.h                                          |    5 
 kernel/rcu/tree_exp.h                                      |   22 
 kernel/rcu/tree_plugin.h                                   |   83 +-
 kernel/rcu/update.c                                        |   58 -
 tools/testing/selftests/rcutorture/configs/rcu/TINY02.boot |    2 
 tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot |    2 
 tools/testing/selftests/rcutorture/configs/rcu/TREE04.boot |    2 
 tools/testing/selftests/rcutorture/configs/rcu/TREE05.boot |    2 
 tools/testing/selftests/rcutorture/configs/rcu/TREE06.boot |    2 
 tools/testing/selftests/rcutorture/configs/rcu/TREE08.boot |    2 
 24 files changed, 366 insertions(+), 725 deletions(-)