[PATCH tip/core/rcu 74/88] rcu: Remove *_SLOW_* Kconfig options

From: Paul E. McKenney
Date: Thu May 25 2017 - 18:14:31 EST

The RCU_TORTURE_TEST_SLOW_PREINIT, RCU_TORTURE_TEST_SLOW_PREINIT_DELAY,
RCU_TORTURE_TEST_SLOW_PREINIT_DELAY, RCU_TORTURE_TEST_SLOW_INIT,
RCU_TORTURE_TEST_SLOW_INIT_DELAY, RCU_TORTURE_TEST_SLOW_CLEANUP,
and RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY Kconfig options are only
useful for torture testing, and there are the rcutree.gp_cleanup_delay,
rcutree.gp_init_delay, and rcutree.gp_preinit_delay kernel boot parameters
that rcutorture can use instead. The effect of these parameters is to
artificially slow down grace period initialization and cleanup in order
to make some types of race conditions happen more often.

This commit therefore simplifies Tree RCU a bit by removing the Kconfig
options and adding the corresponding kernel parameters to rcutorture's
.boot files instead. However, this commit also leaves out the kernel
parameters for TREE02, TREE04, and TREE07 in order to have about the
same number of tests slowed as not slowed. TREE01, TREE03, TREE05,
and TREE06 are slowed, and the rest are not slowed.

Reported-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/kernel-parameters.txt | 10 +--
kernel/rcu/tree.c | 26 ++------
kernel/rcu/tree_plugin.h | 6 +-
lib/Kconfig.debug | 75 ----------------------
.../selftests/rcutorture/configs/rcu/TREE01 | 3 -
.../selftests/rcutorture/configs/rcu/TREE01.boot | 3 +
.../selftests/rcutorture/configs/rcu/TREE02 | 3 -
.../selftests/rcutorture/configs/rcu/TREE03 | 3 -
.../selftests/rcutorture/configs/rcu/TREE03.boot | 3 +
.../selftests/rcutorture/configs/rcu/TREE04 | 3 -
.../selftests/rcutorture/configs/rcu/TREE05 | 3 -
.../selftests/rcutorture/configs/rcu/TREE05.boot | 3 +
.../selftests/rcutorture/configs/rcu/TREE06 | 3 -
.../selftests/rcutorture/configs/rcu/TREE06.boot | 3 +
.../selftests/rcutorture/configs/rcu/TREE07 | 3 -
.../selftests/rcutorture/doc/TREE_RCU-kconfig.txt | 9 ---
16 files changed, 24 insertions(+), 135 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 6671f9b60a86..f85bfe02f052 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3229,21 +3229,17 @@

rcutree.gp_cleanup_delay= [KNL]
Set the number of jiffies to delay each step of
- RCU grace-period cleanup. This only has effect
- when CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP is set.
+ RCU grace-period cleanup.

rcutree.gp_init_delay= [KNL]
Set the number of jiffies to delay each step of
- RCU grace-period initialization. This only has
- effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT
- is set.
+ RCU grace-period initialization.

rcutree.gp_preinit_delay= [KNL]
Set the number of jiffies to delay each step of
RCU grace-period pre-initialization, that is,
the propagation of recent CPU-hotplug changes up
- the rcu_node combining tree. This only has effect
- when CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT is set.
+ the rcu_node combining tree.

rcutree.rcu_fanout_exact= [KNL]
Disable autobalancing of the rcu_node combining
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index cac24f5d3fd2..bbbddd85906b 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -177,26 +177,12 @@ module_param(kthread_prio, int, 0644);

/* Delay in jiffies for grace-period initialization delays, debug only. */

-#ifdef CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT
-static int gp_preinit_delay = CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT_DELAY;
-module_param(gp_preinit_delay, int, 0644);
-#else /* #ifdef CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT */
-static const int gp_preinit_delay;
-#endif /* #else #ifdef CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT */
-
-#ifdef CONFIG_RCU_TORTURE_TEST_SLOW_INIT
-static int gp_init_delay = CONFIG_RCU_TORTURE_TEST_SLOW_INIT_DELAY;
-module_param(gp_init_delay, int, 0644);
-#else /* #ifdef CONFIG_RCU_TORTURE_TEST_SLOW_INIT */
-static const int gp_init_delay;
-#endif /* #else #ifdef CONFIG_RCU_TORTURE_TEST_SLOW_INIT */
-
-#ifdef CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP
-static int gp_cleanup_delay = CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY;
-module_param(gp_cleanup_delay, int, 0644);
-#else /* #ifdef CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP */
-static const int gp_cleanup_delay;
-#endif /* #else #ifdef CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP */
+static int gp_preinit_delay;
+module_param(gp_preinit_delay, int, 0444);
+static int gp_init_delay;
+module_param(gp_init_delay, int, 0444);
+static int gp_cleanup_delay;
+module_param(gp_cleanup_delay, int, 0444);

/*
* Number of grace periods between delays, normalized by the duration of
diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h
index 116cf8339826..0553d9fed7d7 100644
--- a/kernel/rcu/tree_plugin.h
+++ b/kernel/rcu/tree_plugin.h
@@ -109,11 +109,11 @@ static void __init rcu_bootup_announce_oddness(void)
pr_info("\tKick kthreads if too-long grace period.\n");
if (IS_ENABLED(CONFIG_DEBUG_OBJECTS_RCU_HEAD))
pr_info("\tRCU callback double-/use-after-free debug enabled.\n");
- if (IS_ENABLED(CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT))
+ if (gp_preinit_delay)
pr_info("\tRCU debug GP pre-init slowdown %d jiffies.\n", gp_preinit_delay);
- if (IS_ENABLED(CONFIG_RCU_TORTURE_TEST_SLOW_INIT))
+ if (gp_init_delay)
pr_info("\tRCU debug GP init slowdown %d jiffies.\n", gp_init_delay);
- if (IS_ENABLED(CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP))
+ if (gp_cleanup_delay)
pr_info("\tRCU debug GP init slowdown %d jiffies.\n", gp_cleanup_delay);
if (IS_ENABLED(CONFIG_RCU_EQS_DEBUG))
pr_info("\tRCU debug extended QS entry/exit.\n");
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index e4587ebe52c7..960c5d2d3c03 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1373,81 +1373,6 @@ config RCU_TORTURE_TEST
Say M if you want the RCU torture tests to build as a module.
Say N if you are unsure.

-config RCU_TORTURE_TEST_SLOW_PREINIT
- bool "Slow down RCU grace-period pre-initialization to expose races"
- depends on RCU_TORTURE_TEST
- help
- This option delays grace-period pre-initialization (the
- propagation of CPU-hotplug changes up the rcu_node combining
- tree) for a few jiffies between initializing each pair of
- consecutive rcu_node structures. This helps to expose races
- involving grace-period pre-initialization, in other words, it
- makes your kernel less stable. It can also greatly increase
- grace-period latency, especially on systems with large numbers
- of CPUs. This is useful when torture-testing RCU, but in
- almost no other circumstance.
-
- Say Y here if you want your system to crash and hang more often.
- Say N if you want a sane system.
-
-config RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
- int "How much to slow down RCU grace-period pre-initialization"
- range 0 5
- default 3
- depends on RCU_TORTURE_TEST_SLOW_PREINIT
- help
- This option specifies the number of jiffies to wait between
- each rcu_node structure pre-initialization step.
-
-config RCU_TORTURE_TEST_SLOW_INIT
- bool "Slow down RCU grace-period initialization to expose races"
- depends on RCU_TORTURE_TEST
- help
- This option delays grace-period initialization for a few
- jiffies between initializing each pair of consecutive
- rcu_node structures. This helps to expose races involving
- grace-period initialization, in other words, it makes your
- kernel less stable. It can also greatly increase grace-period
- latency, especially on systems with large numbers of CPUs.
- This is useful when torture-testing RCU, but in almost no
- other circumstance.
-
- Say Y here if you want your system to crash and hang more often.
- Say N if you want a sane system.
-
-config RCU_TORTURE_TEST_SLOW_INIT_DELAY
- int "How much to slow down RCU grace-period initialization"
- range 0 5
- default 3
- depends on RCU_TORTURE_TEST_SLOW_INIT
- help
- This option specifies the number of jiffies to wait between
- each rcu_node structure initialization.
-
-config RCU_TORTURE_TEST_SLOW_CLEANUP
- bool "Slow down RCU grace-period cleanup to expose races"
- depends on RCU_TORTURE_TEST
- help
- This option delays grace-period cleanup for a few jiffies
- between cleaning up each pair of consecutive rcu_node
- structures. This helps to expose races involving grace-period
- cleanup, in other words, it makes your kernel less stable.
- It can also greatly increase grace-period latency, especially
- on systems with large numbers of CPUs. This is useful when
- torture-testing RCU, but in almost no other circumstance.
-
- Say Y here if you want your system to crash and hang more often.
- Say N if you want a sane system.
-
-config RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
- int "How much to slow down RCU grace-period cleanup"
- range 0 5
- default 3
- depends on RCU_TORTURE_TEST_SLOW_CLEANUP
- help
- This option specifies the number of jiffies to wait between
- each rcu_node structure cleanup operation.
-
config RCU_CPU_STALL_TIMEOUT
int "RCU CPU stall timeout in seconds"
depends on RCU_STALL_COMMON
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE01 b/tools/testing/selftests/rcutorture/configs/rcu/TREE01
index cc6c5815236e..92ca49f90ef9 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE01
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE01
@@ -17,6 +17,3 @@ CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_RCU_BOOST=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
-CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot b/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot
index adc3abc82fb8..89705ed79596 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE01.boot
@@ -1 +1,4 @@
rcutorture.torture_type=rcu_bh maxcpus=8
+rcutree.gp_preinit_delay=3
+rcutree.gp_init_delay=3
+rcutree.gp_cleanup_delay=3
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE02 b/tools/testing/selftests/rcutorture/configs/rcu/TREE02
index 1cecab330ba0..35e639e39366 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE02
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE02
@@ -19,8 +19,5 @@ CONFIG_DEBUG_LOCK_ALLOC=y
CONFIG_PROVE_LOCKING=n
CONFIG_RCU_BOOST=n
CONFIG_RCU_EXPERT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
-CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y
CONFIG_DEBUG_OBJECTS=y
CONFIG_DEBUG_OBJECTS_RCU_HEAD=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE03 b/tools/testing/selftests/rcutorture/configs/rcu/TREE03
index 3b93ee544e70..7a17c503b382 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE03
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE03
@@ -17,6 +17,3 @@ CONFIG_RCU_BOOST=y
CONFIG_RCU_KTHREAD_PRIO=2
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
-CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE03.boot b/tools/testing/selftests/rcutorture/configs/rcu/TREE03.boot
index 120c0c88d100..9ef3aed126e9 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE03.boot
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE03.boot
@@ -1 +1,4 @@
rcutorture.onoff_interval=1 rcutorture.onoff_holdoff=30
+rcutree.gp_preinit_delay=3
+rcutree.gp_init_delay=3
+rcutree.gp_cleanup_delay=3
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE04 b/tools/testing/selftests/rcutorture/configs/rcu/TREE04
index 851c01ae2cea..27d22695d64c 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE04
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE04
@@ -18,7 +18,4 @@ CONFIG_RCU_FANOUT_LEAF=3
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
-CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y
CONFIG_RCU_EQS_DEBUG=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE05 b/tools/testing/selftests/rcutorture/configs/rcu/TREE05
index d4cdc0d74e16..1257d3227b1e 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE05
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE05
@@ -19,6 +19,3 @@ CONFIG_PROVE_LOCKING=y
#CHECK#CONFIG_PROVE_RCU=y
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
-CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE05.boot b/tools/testing/selftests/rcutorture/configs/rcu/TREE05.boot
index 15b3e1a86f74..c7fd050dfcd9 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE05.boot
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE05.boot
@@ -1,2 +1,5 @@
rcutorture.torture_type=sched
rcupdate.rcu_self_test_sched=1
+rcutree.gp_preinit_delay=3
+rcutree.gp_init_delay=3
+rcutree.gp_cleanup_delay=3
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE06 b/tools/testing/selftests/rcutorture/configs/rcu/TREE06
index 9215827649bd..05a4eec3f27b 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE06
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE06
@@ -21,6 +21,3 @@ CONFIG_PROVE_LOCKING=y
CONFIG_DEBUG_OBJECTS=y
CONFIG_DEBUG_OBJECTS_RCU_HEAD=y
CONFIG_RCU_EXPERT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
-CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE06.boot b/tools/testing/selftests/rcutorture/configs/rcu/TREE06.boot
index dd90f28ed700..ad18b52a2cad 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE06.boot
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE06.boot
@@ -2,3 +2,6 @@ rcupdate.rcu_self_test=1
rcupdate.rcu_self_test_bh=1
rcupdate.rcu_self_test_sched=1
rcutree.rcu_fanout_exact=1
+rcutree.gp_preinit_delay=3
+rcutree.gp_init_delay=3
+rcutree.gp_cleanup_delay=3
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TREE07 b/tools/testing/selftests/rcutorture/configs/rcu/TREE07
index 99f04e4c5162..b9ddd3beeb9a 100644
--- a/tools/testing/selftests/rcutorture/configs/rcu/TREE07
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TREE07
@@ -17,6 +17,3 @@ CONFIG_RCU_FANOUT_LEAF=2
CONFIG_DEBUG_LOCK_ALLOC=n
CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
CONFIG_RCU_EXPERT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y
-CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y
-CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y
diff --git a/tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt b/tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt
index 364801b1a230..1dfec4657d95 100644
--- a/tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt
+++ b/tools/testing/selftests/rcutorture/doc/TREE_RCU-kconfig.txt
@@ -28,9 +28,6 @@ CONFIG_RCU_TRACE -- Do half.
CONFIG_SMP -- Need one !SMP for PREEMPT_RCU.
CONFIG_RCU_EXPERT=n -- Do a few, but these have to be vanilla configurations.
CONFIG_RCU_EQS_DEBUG -- Do at least one for CONFIG_NO_HZ_FULL and not.
-CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP -- Do for all but a couple TREE scenarios.
-CONFIG_RCU_TORTURE_TEST_SLOW_INIT -- Do for all but a couple TREE scenarios.
-CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT -- Do for all but a couple TREE scenarios.

RCU-bh: Do one with PREEMPT and one with !PREEMPT.
RCU-sched: Do one with PREEMPT but not BOOST.
@@ -78,12 +75,6 @@ CONFIG_RCU_TORTURE_TEST_RUNNABLE

Always used in KVM testing.

-CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT_DELAY
-CONFIG_RCU_TORTURE_TEST_SLOW_INIT_DELAY
-CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP_DELAY
-
- Inspection suffices, ignore.
-
CONFIG_PREEMPT_RCU
CONFIG_TREE_RCU
CONFIG_TINY_RCU
--
2.5.2