Commit 0999f615 authored by Frederic Weisbecker's avatar Frederic Weisbecker Committed by Joel Fernandes
Browse files

rcu: Remove swake_up_one_online() bandaid 

It's now ok to perform a wake-up from an offline CPU because the
resulting armed scheduler bandwidth hrtimers are now correctly targeted
by hrtimer infrastructure.

Remove the obsolete hackerry.

Link: https://lore.kernel.org/all/20241231170712.149394-3-frederic@kernel.org/


Reviewed-by: default avatarUsama Arif <usamaarif642@gmail.com>
Reviewed-by: default avatarJoel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: default avatarFrederic Weisbecker <frederic@kernel.org>
Signed-off-by: default avatarJoel Fernandes <joelagnelf@nvidia.com>
parent 79b265a2

kernel/rcu/tree.c

+1 −33
Original line number Diff line number Diff line
@@ -1060,38 +1060,6 @@ static bool rcu_future_gp_cleanup(struct rcu_node *rnp) 
	return needmore;

}



static void swake_up_one_online_ipi(void *arg)

{

	struct swait_queue_head *wqh = arg;



	swake_up_one(wqh);

}



static void swake_up_one_online(struct swait_queue_head *wqh)

{

	int cpu = get_cpu();



	/*

	 * If called from rcutree_report_cpu_starting(), wake up

	 * is dangerous that late in the CPU-down hotplug process. The

	 * scheduler might queue an ignored hrtimer. Defer the wake up

	 * to an online CPU instead.

	 */

	if (unlikely(cpu_is_offline(cpu))) {

		int target;



		target = cpumask_any_and(housekeeping_cpumask(HK_TYPE_RCU),

					 cpu_online_mask);



		smp_call_function_single(target, swake_up_one_online_ipi,

					 wqh, 0);

		put_cpu();

	} else {

		put_cpu();

		swake_up_one(wqh);

	}

}



/*

 * Awaken the grace-period kthread.  Don't do a self-awaken (unless in an

 * interrupt or softirq handler, in which case we just might immediately
@@ -1116,7 +1084,7 @@ static void rcu_gp_kthread_wake(void) 
		return;

	WRITE_ONCE(rcu_state.gp_wake_time, jiffies);

	WRITE_ONCE(rcu_state.gp_wake_seq, READ_ONCE(rcu_state.gp_seq));

	swake_up_one_online(&rcu_state.gp_wq);

	swake_up_one(&rcu_state.gp_wq);

}



/*

kernel/rcu/tree_exp.h

+1 −1
Original line number Diff line number Diff line
@@ -200,7 +200,7 @@ static void __rcu_report_exp_rnp(struct rcu_node *rnp, 
		if (rnp->parent == NULL) {

			raw_spin_unlock_irqrestore_rcu_node(rnp, flags);

			if (wake)

				swake_up_one_online(&rcu_state.expedited_wq);

				swake_up_one(&rcu_state.expedited_wq);



			break;

		}

kernel/rcu/tree_nocb.h

+1 −1
Original line number Diff line number Diff line
@@ -216,7 +216,7 @@ static bool __wake_nocb_gp(struct rcu_data *rdp_gp, 
	raw_spin_unlock_irqrestore(&rdp_gp->nocb_gp_lock, flags);

	if (needwake) {

		trace_rcu_nocb_wake(rcu_state.name, rdp->cpu, TPS("DoWake"));

		swake_up_one_online(&rdp_gp->nocb_gp_wq);

		swake_up_one(&rdp_gp->nocb_gp_wq);

	}



	return needwake;