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> 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) { Is READ_ONCE() not required here? - Neeraj > + 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"));