diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcupdate.c | 5 | ||||
| -rw-r--r-- | kernel/rcutree.c | 29 | ||||
| -rw-r--r-- | kernel/rcutree_plugin.h | 1 |
3 files changed, 35 insertions, 0 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index 2bc4e135ff23..a86f1741cc27 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -88,6 +88,9 @@ EXPORT_SYMBOL_GPL(debug_lockdep_rcu_enabled); * section. * * Check debug_lockdep_rcu_enabled() to prevent false positives during boot. + * + * Note that rcu_read_lock() is disallowed if the CPU is either idle or + * offline from an RCU perspective, so check for those as well. */ int rcu_read_lock_bh_held(void) { @@ -95,6 +98,8 @@ int rcu_read_lock_bh_held(void) return 1; if (rcu_is_cpu_idle()) return 0; + if (!rcu_lockdep_current_cpu_online()) + return 0; return in_softirq() || irqs_disabled(); } EXPORT_SYMBOL_GPL(rcu_read_lock_bh_held); diff --git a/kernel/rcutree.c b/kernel/rcutree.c index dccd2f78db4e..bcf7db2f2fd2 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -591,6 +591,35 @@ int rcu_is_cpu_idle(void) } EXPORT_SYMBOL(rcu_is_cpu_idle); +#ifdef CONFIG_HOTPLUG_CPU + +/* + * Is the current CPU online? Disable preemption to avoid false positives + * that could otherwise happen due to the current CPU number being sampled, + * this task being preempted, its old CPU being taken offline, resuming + * on some other CPU, then determining that its old CPU is now offline. + * It is OK to use RCU on an offline processor during initial boot, hence + * the check for rcu_scheduler_fully_active. + * + * Disable checking if in an NMI handler because we cannot safely report + * errors from NMI handlers anyway. + */ +bool rcu_lockdep_current_cpu_online(void) +{ + bool ret; + + if (in_nmi()) + return 1; + preempt_disable(); + ret = cpu_online(smp_processor_id()) || + !rcu_scheduler_fully_active; + preempt_enable(); + return ret; +} +EXPORT_SYMBOL_GPL(rcu_lockdep_current_cpu_online); + +#endif /* #ifdef CONFIG_HOTPLUG_CPU */ + #endif /* #ifdef CONFIG_PROVE_RCU */ /** diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h index aa93b074bb2f..cecea84f4f3f 100644 --- a/kernel/rcutree_plugin.h +++ b/kernel/rcutree_plugin.h @@ -1946,6 +1946,7 @@ void synchronize_sched_expedited(void) /* Note that atomic_inc_return() implies full memory barrier. */ firstsnap = snap = atomic_inc_return(&sync_sched_expedited_started); get_online_cpus(); + WARN_ON_ONCE(cpu_is_offline(smp_processor_id())); /* * Each pass through the following loop attempts to force a |