Re: [RFC PATCH 1/2] rcu: Add rcu_read_lock_notrace()

["Paul E. McKenney" <paulmck@kernel.org>]

Hello!

This is version 2 of a patch series introducing SRCU-fast to the
__DECLARE_TRACE() in place of the current preemption disabling.
This change enable preemption of BPF programs attached to tracepoints
in in, as is required for runtime use of BPF in real-time systems.

The patches are as follows:

1.	Move rcu_is_watching() checks to srcu_read_{,un}lock_fast().

2.	Add srcu_read_lock_fast_notrace() and
	srcu_read_unlock_fast_notrace().

3.	Add guards for notrace variants of SRCU-fast readers.

4.	Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast.

Changes since RFC version:

o	RFC patch 6/4 has been pulled into the shared RCU tree:
	e88c632a8698 ("srcu: Add guards for SRCU-fast readers")

o	RFC patch 5/4 (which removed the now-unnecessary special boot-time
	avoidance of SRCU) has been folded into patch 4/4 shown above,
	as suggested by Steven Rostedt.

						Thanx, Paul

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

 b/include/linux/srcu.h       |    4 ++++
 b/include/linux/srcutree.h   |    2 --
 b/include/linux/tracepoint.h |    6 ++++--
 b/kernel/tracepoint.c        |   21 ++++++++++++++++++++-
 include/linux/srcu.h         |   30 ++++++++++++++++++++++++++++++
 5 files changed, 58 insertions(+), 5 deletions(-)