[PATCH tip/core/rcu 0/12] NO_HZ fixes for v5.5

[Paul E. McKenney]

Hello!

This series contains various fixes for NO_HZ and NO_HZ_FULL problems,
including re-enabling the tick during long-term kernel-mode execution.

1.	Add TICK_DEP_BIT_RCU (which allows RCU-specific tick re-enabling),
	courtesy of Frederic Weisbecker.

2.	Export tick start/stop functions for rcutorture.

3.	Force on tick when invoking lots of callbacks.

4.	Force on tick for rcutorture readers and callback flooders.

5.	Provide RCU quiescent state in multi_cpu_stop().

6.	Make CPU-hotplug removal operations enable tick.

7.	Use {READ,WRITE)_ONCE() for multi_cpu_stop() ->state.

8.	Force tick on for nohz_full CPUs not reaching quiescent states.

9.	Force nohz_full tick on upon irq enter instead of exit.

10.	Reset CPU hints when reporting a quiescent state, courtesy of
	Joel Fernandes.

11.	Confine ->core_needs_qs accesses to the corresponding CPU.

12.	Make kernel-mode nohz_full CPUs invoke the RCU core processing.

							Thanx, Paul

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

 include/linux/rcutree.h      |    1 
 include/linux/tick.h         |    7 ++
 include/trace/events/timer.h |    3 -
 kernel/rcu/rcutorture.c      |   20 +++++---
 kernel/rcu/tree.c            |  105 ++++++++++++++++++++++++++++++-------------
 kernel/rcu/tree.h            |    1 
 kernel/stop_machine.c        |    7 +-
 kernel/time/tick-sched.c     |   11 ++++
 8 files changed, 114 insertions(+), 41 deletions(-)