diff options
Diffstat (limited to 'kernel/rcu/tree_stall.h')
-rw-r--r-- | kernel/rcu/tree_stall.h | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h new file mode 100644 index 000000000000..682189f4d083 --- /dev/null +++ b/kernel/rcu/tree_stall.h @@ -0,0 +1,63 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * RCU CPU stall warnings for normal RCU grace periods + * + * Copyright IBM Corporation, 2019 + * + * Author: Paul E. McKenney <paulmck@linux.ibm.com> + */ + + +#ifdef CONFIG_PROVE_RCU +#define RCU_STALL_DELAY_DELTA (5 * HZ) +#else +#define RCU_STALL_DELAY_DELTA 0 +#endif + +int rcu_jiffies_till_stall_check(void) +{ + int till_stall_check = READ_ONCE(rcu_cpu_stall_timeout); + + /* + * Limit check must be consistent with the Kconfig limits + * for CONFIG_RCU_CPU_STALL_TIMEOUT. + */ + if (till_stall_check < 3) { + WRITE_ONCE(rcu_cpu_stall_timeout, 3); + till_stall_check = 3; + } else if (till_stall_check > 300) { + WRITE_ONCE(rcu_cpu_stall_timeout, 300); + till_stall_check = 300; + } + return till_stall_check * HZ + RCU_STALL_DELAY_DELTA; +} +EXPORT_SYMBOL_GPL(rcu_jiffies_till_stall_check); + +void rcu_sysrq_start(void) +{ + if (!rcu_cpu_stall_suppress) + rcu_cpu_stall_suppress = 2; +} + +void rcu_sysrq_end(void) +{ + if (rcu_cpu_stall_suppress == 2) + rcu_cpu_stall_suppress = 0; +} + +static int rcu_panic(struct notifier_block *this, unsigned long ev, void *ptr) +{ + rcu_cpu_stall_suppress = 1; + return NOTIFY_DONE; +} + +static struct notifier_block rcu_panic_block = { + .notifier_call = rcu_panic, +}; + +static int __init check_cpu_stall_init(void) +{ + atomic_notifier_chain_register(&panic_notifier_list, &rcu_panic_block); + return 0; +} +early_initcall(check_cpu_stall_init); |