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Commit 90040c9e authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Remove *_SLOW_* Kconfig options 



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: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent a3883df3

Documentation/admin-guide/kernel-parameters.txt

+3 −7
Original line number Diff line number Diff line
@@ -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

kernel/rcu/tree.c

+6 −20
Original line number Diff line number Diff line
@@ -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

kernel/rcu/tree_plugin.h

+3 −3
Original line number Diff line number Diff line
@@ -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");

lib/Kconfig.debug

+0 −75
Original line number Diff line number Diff line
@@ -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

tools/testing/selftests/rcutorture/configs/rcu/TREE01

+0 −3
Original line number Diff line number Diff line
@@ -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