[PATCH tip/core/rcu 0/12] RCU Kconfig fixes for v4.2

From: Paul E. McKenney
Date: Tue Apr 21 2015 - 15:55:50 EST


Hello!

This patch series reduces the number of questions that RCU asks Kconfig
users. After this series is applied, removing the RCU-related definitions
from .config and running "make oldconfig" results in only the following:

RCU Implementation
> 1. Tree-based hierarchical RCU (TREE_RCU) (NEW)
choice[1]: 1
Make expert-level adjustments to RCU configuration (RCU_EXPERT) [N/y/?] (NEW)

Those expert users wishing to tune RCU answer Y to this question.

The patches in this series are as follows:

1. Drive TASKS_RCU directly from Kconfig, for example, by having
RCU_TORTURE_TESTS select it.

2. Remove CONFIG_TASKS_RCU=y from the three TASKS_RCU test
scenarios, since this is set by virtue of having rcutorture
configured.

3. Drive RCU_USER_QS directly from Kconfig, relying on the fact
that NO_HZ_FULL selects it.

4. Convert CONFIG_RCU_FANOUT_EXACT to a boot parameter, where it
is used by rcutorture.

5. Update rcutorture test scenarios to use the boot parameter
created in #4 instead of the Kconfig parameter.

6. Create a boot parameter to do a diagnostic dump of the shape
of the rcu_node combining tree, which is useful for verifying
that intended changes to that tree actually happened.

7. Create an RCU_EXPERT Kconfig parameter and hide the
RCU_FAST_NO_HZ, RCU_BOOST, CONTEXT_TRACKING_FORCE, and
RCU_NOCB_CPU boolean parameters behind it.

8. Make rcutorture test scenarios force RCU_EXPERT, but have
SRCU-P, TASKS03, and TREE09 retain !RCU_EXPERT in order to
test the vanilla configuration.

9. Remove the dependency of RCU_FANOUT_LEAF on RCU_FANOUT.

10. Change RCU to allow it to tolerate an undefined RCU_FANOUT,
and then hide RCU_FANOUT behind RCU_EXPERT.

11. Change RCU to allow it to tolerate an undefined RCU_FANOUT_LEAF,
and then hide RCU_FANOUT_LEAF behind RCU_EXPERT.

12. Change RCU to allow it to tolerate an undefined RCU_KTHREAD_PRIO,
and then hide RCU_KTHREAD_PRIO behind RCU_EXPERT.

Thanx, Paul

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

b/Documentation/kernel-parameters.txt | 11 +
b/init/Kconfig | 62 ++++------
b/kernel/rcu/tree.c | 50 ++++++--
b/kernel/rcu/tree.h | 29 ++++
b/kernel/rcu/tree_plugin.h | 14 +-
b/lib/Kconfig.debug | 1
b/tools/testing/selftests/rcutorture/configs/rcu/SRCU-N | 1
b/tools/testing/selftests/rcutorture/configs/rcu/TASKS01 | 2
b/tools/testing/selftests/rcutorture/configs/rcu/TASKS02 | 1
b/tools/testing/selftests/rcutorture/configs/rcu/TASKS03 | 1
b/tools/testing/selftests/rcutorture/configs/rcu/TREE01 | 1
b/tools/testing/selftests/rcutorture/configs/rcu/TREE02 | 2
b/tools/testing/selftests/rcutorture/configs/rcu/TREE02-T | 1
b/tools/testing/selftests/rcutorture/configs/rcu/TREE03 | 2
b/tools/testing/selftests/rcutorture/configs/rcu/TREE04 | 2
b/tools/testing/selftests/rcutorture/configs/rcu/TREE05 | 2
b/tools/testing/selftests/rcutorture/configs/rcu/TREE06 | 2
b/tools/testing/selftests/rcutorture/configs/rcu/TREE06.boot | 1
b/tools/testing/selftests/rcutorture/configs/rcu/TREE07 | 2
b/tools/testing/selftests/rcutorture/configs/rcu/TREE08 | 2
b/tools/testing/selftests/rcutorture/configs/rcu/TREE08-T | 1
b/tools/testing/selftests/rcutorture/configs/rcu/TREE08-T.boot | 1
b/tools/testing/selftests/rcutorture/configs/rcu/TREE08.boot | 1
23 files changed, 127 insertions(+), 65 deletions(-)

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