diff options
| -rw-r--r-- | Documentation/kernel-parameters.txt | 16 | ||||
| -rw-r--r-- | kernel/rcu/tree.c | 29 | ||||
| -rw-r--r-- | lib/Kconfig.debug | 54 | ||||
| -rw-r--r-- | tools/testing/selftests/rcutorture/configs/rcu/CFcommon | 2 |
4 files changed, 93 insertions, 8 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 61ab1628a057..10a4fb80c033 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -2992,11 +2992,23 @@ bytes respectively. Such letter suffixes can also be entirely omitted. Set maximum number of finished RCU callbacks to process in one batch. + 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. + 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. + effect when CONFIG_RCU_TORTURE_TEST_SLOW_INIT + is set. + + 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. rcutree.rcu_fanout_leaf= [KNL] Increase the number of CPUs assigned to each diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 9b076b284695..2f3cb5513ca3 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -163,6 +163,14 @@ static int kthread_prio = CONFIG_RCU_KTHREAD_PRIO; 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); @@ -170,6 +178,13 @@ module_param(gp_init_delay, int, 0644); 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 */ + /* * Number of grace periods between delays, normalized by the duration of * the delay. The longer the the delay, the more the grace periods between @@ -1742,6 +1757,13 @@ static void note_gp_changes(struct rcu_state *rsp, struct rcu_data *rdp) rcu_gp_kthread_wake(rsp); } +static void rcu_gp_slow(struct rcu_state *rsp, int delay) +{ + if (delay > 0 && + !(rsp->gpnum % (rcu_num_nodes * PER_RCU_NODE_PERIOD * delay))) + schedule_timeout_uninterruptible(delay); +} + /* * Initialize a new grace period. Return 0 if no grace period required. */ @@ -1784,6 +1806,7 @@ static int rcu_gp_init(struct rcu_state *rsp) * will handle subsequent offline CPUs. */ rcu_for_each_leaf_node(rsp, rnp) { + rcu_gp_slow(rsp, gp_preinit_delay); raw_spin_lock_irq(&rnp->lock); smp_mb__after_unlock_lock(); if (rnp->qsmaskinit == rnp->qsmaskinitnext && @@ -1840,6 +1863,7 @@ static int rcu_gp_init(struct rcu_state *rsp) * process finishes, because this kthread handles both. */ rcu_for_each_node_breadth_first(rsp, rnp) { + rcu_gp_slow(rsp, gp_init_delay); raw_spin_lock_irq(&rnp->lock); smp_mb__after_unlock_lock(); rdp = this_cpu_ptr(rsp->rda); @@ -1857,10 +1881,6 @@ static int rcu_gp_init(struct rcu_state *rsp) raw_spin_unlock_irq(&rnp->lock); cond_resched_rcu_qs(); WRITE_ONCE(rsp->gp_activity, jiffies); - if (gp_init_delay > 0 && - !(rsp->gpnum % - (rcu_num_nodes * PER_RCU_NODE_PERIOD * gp_init_delay))) - schedule_timeout_uninterruptible(gp_init_delay); } return 1; @@ -1955,6 +1975,7 @@ static void rcu_gp_cleanup(struct rcu_state *rsp) raw_spin_unlock_irq(&rnp->lock); cond_resched_rcu_qs(); WRITE_ONCE(rsp->gp_activity, jiffies); + rcu_gp_slow(rsp, gp_cleanup_delay); } rnp = rcu_get_root(rsp); raw_spin_lock_irq(&rnp->lock); diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index ba2b0c87e65b..e1af93ae246b 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1261,12 +1261,38 @@ 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_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 makes grace-period initialization block for a - few jiffies between initializing each pair of consecutive + 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 @@ -1286,6 +1312,30 @@ config RCU_TORTURE_TEST_SLOW_INIT_DELAY 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/CFcommon b/tools/testing/selftests/rcutorture/configs/rcu/CFcommon index 49701218dc62..f824b4c9d9d9 100644 --- a/tools/testing/selftests/rcutorture/configs/rcu/CFcommon +++ b/tools/testing/selftests/rcutorture/configs/rcu/CFcommon @@ -1,3 +1,5 @@ CONFIG_RCU_TORTURE_TEST=y CONFIG_PRINTK_TIME=y +CONFIG_RCU_TORTURE_TEST_SLOW_CLEANUP=y CONFIG_RCU_TORTURE_TEST_SLOW_INIT=y +CONFIG_RCU_TORTURE_TEST_SLOW_PREINIT=y |