[PATCH tip/core/rcu 0/12] Forward-progress changes for v5.1

[Paul E. McKenney]

Hello!

This series contains commits that improve RCU's ability to make forward
progress on grace periods:

1.	Accommodate zero jiffies_till_first_fqs and kthread kicking.

2-6.	Move per-CPU variables to rcu_data structure, now that rcu_data
	is strictly per-CPU itself due to there only being one flavor.
	Also remove rcu_cpu_kthread_loops and rcu_cpu_kthread_cpu,
	which are unused.

7.	Update outdated NOCB comments.

8.	Improve diagnostics for failed RCU grace-period start.

9.	Protect rcu_check_gp_kthread_starvation() access to ->gp_flags.

10.	Add sysrq rcu_node-dump capability to assist with debugging of
	forward-progress issues.

11.	Do RCU GP kthread self-wakeup from softirq and interrupt, thus
	fixing a grace-period hang, courtesy of Jun Zhang.

12.	Prevent needless ->gp_seq_needed update in __note_gp_changes(),
	courtesy of Jun Zhang.

							Thanx, Paul

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

 Documentation/admin-guide/kernel-parameters.txt |    5 +
 kernel/rcu/tree.c                               |  106 ++++++++++++++++--------
 kernel/rcu/tree.h                               |   19 ++--
 kernel/rcu/tree_plugin.h                        |   68 ++++++---------
 4 files changed, 117 insertions(+), 81 deletions(-)