[PATCH rcu 0/21] SRCU updates for v5.19

[Paul E. McKenney]

Hello!

This series contains SRCU updates, primarily reducing the srcu_struct
structure's infamous memory footprint.

1.	Tighten cleanup_srcu_struct() GP checks.

2.	Fix s/is/if/ typo in srcu_node comment.

3.	Make srcu_funnel_gp_start() cache ->mynode in snp_leaf.

4.	Make Tree SRCU able to operate without snp_node array.

5.	Dynamically allocate srcu_node array.

6.	Add size-state transitioning code.

7.	Make rcutorture dump the SRCU size state.

8.	Compute snp_seq earlier in srcu_funnel_gp_start().

9.	Use invalid initial value for srcu_node GP sequence numbers.

10.	Ensure snp nodes tree is fully initialized before traversal,
	courtesy of Neeraj Upadhyay.

11.	Add boot-time control over srcu_node array allocation.

12.	Use export for srcu_struct defined by DEFINE_STATIC_SRCU(),
	courtesy of Alexander Aring.

13.	Avoid NULL dereference in srcu_torture_stats_print().

14.	Prevent cleanup_srcu_struct() from freeing non-dynamic ->sda.

15.	Explain srcu_funnel_gp_start() call to list_add() is safe.

16.	Create concurrency-safe helper for initiating size transition.

17.	Add contention-triggered addition of srcu_node tree.

18.	Automatically determine size-transition strategy at boot.

19.	Add contention check to call_srcu() srcu_data ->lock acquisition.

20.	Prevent expedited GPs and blocking readers from consuming CPU.

21.	Drop needless initialization of sdp in srcu_gp_start(), courtesy
	of Lukas Bulwahn.

						Thanx, Paul

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

 Documentation/admin-guide/kernel-parameters.txt   |   18 
 b/Documentation/admin-guide/kernel-parameters.txt |   13 
 b/include/linux/srcutree.h                        |    8 
 b/kernel/rcu/srcutree.c                           |    6 
 include/linux/srcutree.h                          |   24 
 kernel/rcu/srcutree.c                             |  751 +++++++++++++++-------
 6 files changed, 587 insertions(+), 233 deletions(-)