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Commit 2dba13f0 authored by Paul E. McKenney's avatar Paul E. McKenney
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rcu: Switch urgent quiescent-state requests to rcu_data structure 



This commit removes ->rcu_need_heavy_qs and ->rcu_urgent_qs from the
rcu_dynticks structure and updates the code to access them from the
rcu_data structure.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
parent c458a89e

kernel/rcu/tree.c

+6 −6
Original line number Diff line number Diff line
@@ -362,7 +362,7 @@ static void __maybe_unused rcu_momentary_dyntick_idle(void) 
	struct rcu_dynticks *rdtp = this_cpu_ptr(&rcu_dynticks);

	int special;



	raw_cpu_write(rcu_dynticks.rcu_need_heavy_qs, false);

	raw_cpu_write(rcu_data.rcu_need_heavy_qs, false);

	special = atomic_add_return(2 * RCU_DYNTICK_CTRL_CTR, &rdtp->dynticks);

	/* It is illegal to call this from idle state. */

	WARN_ON_ONCE(!(special & RCU_DYNTICK_CTRL_CTR));
@@ -928,7 +928,7 @@ void rcu_request_urgent_qs_task(struct task_struct *t) 
	cpu = task_cpu(t);

	if (!task_curr(t))

		return; /* This task is not running on that CPU. */

	smp_store_release(per_cpu_ptr(&rcu_dynticks.rcu_urgent_qs, cpu), true);

	smp_store_release(per_cpu_ptr(&rcu_data.rcu_urgent_qs, cpu), true);

}



#if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU)
@@ -1081,8 +1081,8 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) 
	 * is set way high.

	 */

	jtsq = READ_ONCE(jiffies_to_sched_qs);

	ruqp = per_cpu_ptr(&rcu_dynticks.rcu_urgent_qs, rdp->cpu);

	rnhqp = &per_cpu(rcu_dynticks.rcu_need_heavy_qs, rdp->cpu);

	ruqp = per_cpu_ptr(&rcu_data.rcu_urgent_qs, rdp->cpu);

	rnhqp = &per_cpu(rcu_data.rcu_need_heavy_qs, rdp->cpu);

	if (!READ_ONCE(*rnhqp) &&

	    (time_after(jiffies, rcu_state.gp_start + jtsq * 2) ||

	     time_after(jiffies, rcu_state.jiffies_resched))) {
@@ -2499,13 +2499,13 @@ void rcu_check_callbacks(int user) 
	trace_rcu_utilization(TPS("Start scheduler-tick"));

	raw_cpu_inc(rcu_data.ticks_this_gp);

	/* The load-acquire pairs with the store-release setting to true. */

	if (smp_load_acquire(this_cpu_ptr(&rcu_dynticks.rcu_urgent_qs))) {

	if (smp_load_acquire(this_cpu_ptr(&rcu_data.rcu_urgent_qs))) {

		/* Idle and userspace execution already are quiescent states. */

		if (!rcu_is_cpu_rrupt_from_idle() && !user) {

			set_tsk_need_resched(current);

			set_preempt_need_resched();

		}

		__this_cpu_write(rcu_dynticks.rcu_urgent_qs, false);

		__this_cpu_write(rcu_data.rcu_urgent_qs, false);

	}

	rcu_flavor_check_callbacks(user);

	if (rcu_pending())

kernel/rcu/tree.h

+0 −2
Original line number Diff line number Diff line
@@ -41,8 +41,6 @@ struct rcu_dynticks { 
	long dynticks_nesting;      /* Track process nesting level. */

	long dynticks_nmi_nesting;  /* Track irq/NMI nesting level. */

	atomic_t dynticks;	    /* Even value for idle, else odd. */

	bool rcu_need_heavy_qs;     /* GP old, need heavy quiescent state. */

	bool rcu_urgent_qs;	    /* GP old need light quiescent state. */

};



/* Communicate arguments to a workqueue handler. */

kernel/rcu/tree_exp.h

+1 −1
Original line number Diff line number Diff line
@@ -780,7 +780,7 @@ static void sync_sched_exp_handler(void *unused) 
	}

	__this_cpu_write(rcu_data.cpu_no_qs.b.exp, true);

	/* Store .exp before .rcu_urgent_qs. */

	smp_store_release(this_cpu_ptr(&rcu_dynticks.rcu_urgent_qs), true);

	smp_store_release(this_cpu_ptr(&rcu_data.rcu_urgent_qs), true);

	set_tsk_need_resched(current);

	set_preempt_need_resched();

}

kernel/rcu/tree_plugin.h

+7 −7
Original line number Diff line number Diff line
@@ -967,17 +967,17 @@ void rcu_all_qs(void) 
{

	unsigned long flags;



	if (!raw_cpu_read(rcu_dynticks.rcu_urgent_qs))

	if (!raw_cpu_read(rcu_data.rcu_urgent_qs))

		return;

	preempt_disable();

	/* Load rcu_urgent_qs before other flags. */

	if (!smp_load_acquire(this_cpu_ptr(&rcu_dynticks.rcu_urgent_qs))) {

	if (!smp_load_acquire(this_cpu_ptr(&rcu_data.rcu_urgent_qs))) {

		preempt_enable();

		return;

	}

	this_cpu_write(rcu_dynticks.rcu_urgent_qs, false);

	this_cpu_write(rcu_data.rcu_urgent_qs, false);

	barrier(); /* Avoid RCU read-side critical sections leaking down. */

	if (unlikely(raw_cpu_read(rcu_dynticks.rcu_need_heavy_qs))) {

	if (unlikely(raw_cpu_read(rcu_data.rcu_need_heavy_qs))) {

		local_irq_save(flags);

		rcu_momentary_dyntick_idle();

		local_irq_restore(flags);
@@ -997,10 +997,10 @@ void rcu_note_context_switch(bool preempt) 
	trace_rcu_utilization(TPS("Start context switch"));

	rcu_qs();

	/* Load rcu_urgent_qs before other flags. */

	if (!smp_load_acquire(this_cpu_ptr(&rcu_dynticks.rcu_urgent_qs)))

	if (!smp_load_acquire(this_cpu_ptr(&rcu_data.rcu_urgent_qs)))

		goto out;

	this_cpu_write(rcu_dynticks.rcu_urgent_qs, false);

	if (unlikely(raw_cpu_read(rcu_dynticks.rcu_need_heavy_qs)))

	this_cpu_write(rcu_data.rcu_urgent_qs, false);

	if (unlikely(raw_cpu_read(rcu_data.rcu_need_heavy_qs)))

		rcu_momentary_dyntick_idle();

	if (!preempt)

		rcu_tasks_qs(current);