From 9bae6592d7d74dbb409e0dd8004f13af8b8d569e Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Sun, 18 Jan 2015 18:01:21 -0800 Subject: rcu: Drive PROVE_RCU directly off of PROVE_LOCKING In the past, it has been useful to enable PROVE_LOCKING without also enabling PROVE_RCU. However, experience with PROVE_RCU over the past few years has demonstrated its usefulness, so this commit makes PROVE_LOCKING directly imply PROVE_RCU. Signed-off-by: Paul E. McKenney --- lib/Kconfig.debug | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) (limited to 'lib/Kconfig.debug') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c5cefb3c009c..0766672e4c5f 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1180,16 +1180,7 @@ config DEBUG_CREDENTIALS menu "RCU Debugging" config PROVE_RCU - bool "RCU debugging: prove RCU correctness" - depends on PROVE_LOCKING - default n - help - This feature enables lockdep extensions that check for correct - use of RCU APIs. This is currently under development. Say Y - if you want to debug RCU usage or help work on the PROVE_RCU - feature. - - Say N if you are unsure. + def_bool PROVE_LOCKING config PROVE_RCU_REPEATEDLY bool "RCU debugging: don't disable PROVE_RCU on first splat" -- cgit v1.2.1 From 37745d281069682d901f00c0121949a7d224195f Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 22 Jan 2015 18:24:08 -0800 Subject: rcu: Provide diagnostic option to slow down grace-period initialization Grace-period initialization normally proceeds quite quickly, so that it is very difficult to reproduce races against grace-period initialization. This commit therefore allows grace-period initialization to be artificially slowed down, increasing race-reproduction probability. A pair of new Kconfig parameters are provided, CONFIG_RCU_TORTURE_TEST_SLOW_INIT to enable the slowdowns, and CONFIG_RCU_TORTURE_TEST_SLOW_INIT_DELAY to specify the number of jiffies of slowdown to apply. A boot-time parameter named rcutree.gp_init_delay allows boot-time delay to be specified. By default, no delay will be applied even if CONFIG_RCU_TORTURE_TEST_SLOW_INIT is set. Signed-off-by: Paul E. McKenney --- lib/Kconfig.debug | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'lib/Kconfig.debug') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index c5cefb3c009c..feee8dab441e 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1257,6 +1257,30 @@ config RCU_TORTURE_TEST_RUNNABLE Say N here if you want the RCU torture tests to start only after being manually enabled via /proc. +config RCU_TORTURE_TEST_SLOW_INIT + bool "Slow down RCU grace-period initialization to expose races" + depends on RCU_TORTURE_TEST + help + This option makes grace-period initialization block 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 0 + help + This option specifies the number of jiffies to wait between + each rcu_node structure initialization. + config RCU_CPU_STALL_TIMEOUT int "RCU CPU stall timeout in seconds" depends on RCU_STALL_COMMON -- cgit v1.2.1 From 186bea5d35c821d49e70015d0a6eb73fe9f55d8c Mon Sep 17 00:00:00 2001 From: "Paul E. McKenney" Date: Thu, 29 Jan 2015 16:37:19 -0800 Subject: rcutorture: Default to grace-period-initialization delays Given that CPU-hotplug events are now applied only at the starts of grace periods, it makes sense to unconditionally enable slow grace-period initialization for rcutorture testing. Signed-off-by: Paul E. McKenney --- lib/Kconfig.debug | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'lib/Kconfig.debug') diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index feee8dab441e..1173afc308ad 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1276,7 +1276,7 @@ config RCU_TORTURE_TEST_SLOW_INIT config RCU_TORTURE_TEST_SLOW_INIT_DELAY int "How much to slow down RCU grace-period initialization" range 0 5 - default 0 + default 3 help This option specifies the number of jiffies to wait between each rcu_node structure initialization. -- cgit v1.2.1