Merge branch 'for-mingo' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/rcu

Pull v4.20 RCU changes from Paul E. McKenney:

- Documentation updates, including some good-eye catches from
  Joel Fernandes.

- SRCU updates, most notably changes enabling call_srcu() to be
  invoked very early in the boot sequence.

- Torture-test updates, including some preliminary work towards
  making rcutorture better able to find problems that result in
  insufficient grace-period forward progress.

- Consolidate the RCU-bh, RCU-preempt, and RCU-sched flavors into
  a single flavor similar to RCU-sched in !PREEMPT kernels and
  into a single flavor similar to RCU-preempt (but also waiting
  on preempt-disabled sequences of code) in PREEMPT kernels.  This
  branch also includes a refactoring of rcu_{nmi,irq}_{enter,exit}()
  from Byungchul Park.

- Now that there is only one RCU flavor in any given running kernel,
  the many "rsp" pointers are no longer required, and this cleanup
  series removes them.

- This branch carries out additional cleanups made possible by
  the RCU flavor consolidation, including inlining how-trivial
  functions, updating comments and definitions, and removing
  now-unneeded rcutorture scenarios.

- Initial changes to RCU to better promote forward progress of
  grace periods, including fixing a bug found by Marius Hillenbrand
  and David Woodhouse, with the fix suggested by Peter Zijlstra.

- Now that there is only one flavor of RCU in any running kernel,
  there is also only on rcu_data structure per CPU.  This means
  that the rcu_dynticks structure can be merged into the rcu_data
  structure, a task taken on by this branch.  This branch also
  contains a -rt-related fix from Mike Galbraith.
Signed-off-by: Ingo Molnar <mingo@kernel.org>