diff options
Diffstat (limited to 'kernel/rcu/tree_nocb.h')
| -rw-r--r-- | kernel/rcu/tree_nocb.h | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index 97b99cd06923..2605dd234a13 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -554,13 +554,19 @@ static void __call_rcu_nocb_wake(struct rcu_data *rdp, bool was_alldone, rcu_nocb_unlock(rdp); wake_nocb_gp_defer(rdp, RCU_NOCB_WAKE_LAZY, TPS("WakeLazy")); - } else if (!irqs_disabled_flags(flags)) { + } else if (!irqs_disabled_flags(flags) && cpu_online(rdp->cpu)) { /* ... if queue was empty ... */ rcu_nocb_unlock(rdp); wake_nocb_gp(rdp, false); trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WakeEmpty")); } else { + /* + * Don't do the wake-up upfront on fragile paths. + * Also offline CPUs can't call swake_up_one_online() from + * (soft-)IRQs. Rely on the final deferred wake-up from + * rcutree_report_cpu_dead() + */ rcu_nocb_unlock(rdp); wake_nocb_gp_defer(rdp, RCU_NOCB_WAKE, TPS("WakeEmptyIsDeferred")); @@ -885,7 +891,18 @@ static void nocb_cb_wait(struct rcu_data *rdp) swait_event_interruptible_exclusive(rdp->nocb_cb_wq, nocb_cb_wait_cond(rdp)); if (kthread_should_park()) { - kthread_parkme(); + /* + * kthread_park() must be preceded by an rcu_barrier(). + * But yet another rcu_barrier() might have sneaked in between + * the barrier callback execution and the callbacks counter + * decrement. + */ + if (rdp->nocb_cb_sleep) { + rcu_nocb_lock_irqsave(rdp, flags); + WARN_ON_ONCE(rcu_segcblist_n_cbs(&rdp->cblist)); + rcu_nocb_unlock_irqrestore(rdp, flags); + kthread_parkme(); + } } else if (READ_ONCE(rdp->nocb_cb_sleep)) { WARN_ON(signal_pending(current)); trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("WokeEmpty")); |