On Wed, Dec 21, 2022 at 12:08:49PM -0800, Paul E. McKenney wrote:
> diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h
> index 249c2967d9e6c..7cc4856da0817 100644
> --- a/kernel/rcu/tree_exp.h
> +++ b/kernel/rcu/tree_exp.h
> @@ -594,6 +594,7 @@ static void synchronize_rcu_expedited_wait(void)
> struct rcu_data *rdp;
> struct rcu_node *rnp;
> struct rcu_node *rnp_root = rcu_get_root();
> + unsigned long flags;
>
> trace_rcu_exp_grace_period(rcu_state.name, rcu_exp_gp_seq_endval(), TPS("startwait"));
> jiffies_stall = rcu_exp_jiffies_till_stall_check();
> @@ -602,17 +603,17 @@ static void synchronize_rcu_expedited_wait(void)
> if (synchronize_rcu_expedited_wait_once(1))
> return;
> rcu_for_each_leaf_node(rnp) {
> + raw_spin_lock_irqsave_rcu_node(rnp, flags);
> mask = READ_ONCE(rnp->expmask);
> for_each_leaf_node_cpu_mask(rnp, cpu, mask) {
> rdp = per_cpu_ptr(&rcu_data, cpu);
> if (rdp->rcu_forced_tick_exp)
> continue;
> rdp->rcu_forced_tick_exp = true;
> - preempt_disable();
> if (cpu_online(cpu))
> tick_dep_set_cpu(cpu, TICK_DEP_BIT_RCU_EXP);
> - preempt_enable();
> }
> + raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
> }
> j = READ_ONCE(jiffies_till_first_fqs);
> if (synchronize_rcu_expedited_wait_once(j + HZ))
Reviewed-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
BTW why are we forcing the tick on the whole node?
And shouldn't we set the tick dependency from rcu_exp_handler() instead?
Thanks.
