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Commit 9386c0b7 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu: Rationalize kthread spawning 



Currently, RCU spawns kthreads from several different early_initcall()
functions.  Although this has served RCU well for quite some time,
as more kthreads are added a more deterministic approach is required.
This commit therefore causes all of RCU's early-boot kthreads to be
spawned from a single early_initcall() function.

Signed-off-by: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: default avatarJosh Triplett <josh@joshtriplett.org>
Tested-by: default avatarPaul Gortmaker <paul.gortmaker@windriver.com>
parent f4aa84ba

kernel/rcu/tree.c

+3 −1
Original line number Diff line number Diff line
@@ -3489,7 +3489,7 @@ static int rcu_pm_notify(struct notifier_block *self, 
}



/*

 * Spawn the kthread that handles this RCU flavor's grace periods.

 * Spawn the kthreads that handle each RCU flavor's grace periods.

 */

static int __init rcu_spawn_gp_kthread(void)

{
@@ -3498,6 +3498,7 @@ static int __init rcu_spawn_gp_kthread(void) 
	struct rcu_state *rsp;

	struct task_struct *t;



	rcu_scheduler_fully_active = 1;

	for_each_rcu_flavor(rsp) {

		t = kthread_run(rcu_gp_kthread, rsp, "%s", rsp->name);

		BUG_ON(IS_ERR(t));
@@ -3507,6 +3508,7 @@ static int __init rcu_spawn_gp_kthread(void) 
		raw_spin_unlock_irqrestore(&rnp->lock, flags);

		rcu_spawn_nocb_kthreads(rsp);

	}

	rcu_spawn_boost_kthreads();

	return 0;

}

early_initcall(rcu_spawn_gp_kthread);

kernel/rcu/tree.h

+1 −0
Original line number Diff line number Diff line
@@ -572,6 +572,7 @@ static void rcu_preempt_do_callbacks(void); 
static int rcu_spawn_one_boost_kthread(struct rcu_state *rsp,

						 struct rcu_node *rnp);

#endif /* #ifdef CONFIG_RCU_BOOST */

static void __init rcu_spawn_boost_kthreads(void);

static void rcu_prepare_kthreads(int cpu);

static void rcu_cleanup_after_idle(int cpu);

static void rcu_prepare_for_idle(int cpu);

kernel/rcu/tree_plugin.h

+3 −9
Original line number Diff line number Diff line
@@ -1435,14 +1435,13 @@ static struct smp_hotplug_thread rcu_cpu_thread_spec = { 
};



/*

 * Spawn all kthreads -- called as soon as the scheduler is running.

 * Spawn boost kthreads -- called as soon as the scheduler is running.

 */

static int __init rcu_spawn_kthreads(void)

static void __init rcu_spawn_boost_kthreads(void)

{

	struct rcu_node *rnp;

	int cpu;



	rcu_scheduler_fully_active = 1;

	for_each_possible_cpu(cpu)

		per_cpu(rcu_cpu_has_work, cpu) = 0;

	BUG_ON(smpboot_register_percpu_thread(&rcu_cpu_thread_spec));
@@ -1452,9 +1451,7 @@ static int __init rcu_spawn_kthreads(void) 
		rcu_for_each_leaf_node(rcu_state_p, rnp)

			(void)rcu_spawn_one_boost_kthread(rcu_state_p, rnp);

	}

	return 0;

}

early_initcall(rcu_spawn_kthreads);



static void rcu_prepare_kthreads(int cpu)

{
@@ -1492,12 +1489,9 @@ static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu) 
{

}



static int __init rcu_scheduler_really_started(void)

static void __init rcu_spawn_boost_kthreads(void)

{

	rcu_scheduler_fully_active = 1;

	return 0;

}

early_initcall(rcu_scheduler_really_started);



static void rcu_prepare_kthreads(int cpu)

{