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Commit e26fbffd authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

sched: Allow hotplug notifiers to be setup early 



Prevent the SMP scheduler related notifiers to be executed before the smp
scheduler is initialized and install them early.

This is a preparatory change for further consolidation of the hotplug notifier
maze.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 9cf7243d

kernel/sched/core.c

+36 −23
Original line number Diff line number Diff line
@@ -5195,6 +5195,8 @@ int task_can_attach(struct task_struct *p, 


#ifdef CONFIG_SMP



static bool sched_smp_initialized __read_mostly;



#ifdef CONFIG_NUMA_BALANCING

/* Migrate current task p to target_cpu */

int migrate_task_to(struct task_struct *p, int target_cpu)
@@ -5513,25 +5515,6 @@ int sched_cpu_starting(unsigned int cpu) 
	return 0;

}



static int __init migration_init(void)

{

	void *cpu = (void *)(long)smp_processor_id();

	int err;



	/* Initialize migration for the boot CPU */

	err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);

	BUG_ON(err == NOTIFY_BAD);

	migration_call(&migration_notifier, CPU_ONLINE, cpu);

	register_cpu_notifier(&migration_notifier);



	/* Register cpu active notifiers */

	cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);

	cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);



	return 0;

}

early_initcall(migration_init);



static cpumask_var_t sched_domains_tmpmask; /* sched_domains_mutex */



#ifdef CONFIG_SCHED_DEBUG
@@ -6711,6 +6694,9 @@ static int sched_domains_numa_masks_update(struct notifier_block *nfb, 
{

	int cpu = (long)hcpu;



	if (!sched_smp_initialized)

		return NOTIFY_DONE;



	switch (action & ~CPU_TASKS_FROZEN) {

	case CPU_ONLINE:

		sched_domains_numa_masks_set(cpu);
@@ -7129,6 +7115,9 @@ static int num_cpus_frozen; /* used to mark begin/end of suspend/resume */ 
static int cpuset_cpu_active(struct notifier_block *nfb, unsigned long action,

			     void *hcpu)

{

	if (!sched_smp_initialized)

		return NOTIFY_DONE;



	switch (action) {

	case CPU_ONLINE_FROZEN:

	case CPU_DOWN_FAILED_FROZEN:
@@ -7169,6 +7158,9 @@ static int cpuset_cpu_inactive(struct notifier_block *nfb, unsigned long action, 
	bool overflow;

	int cpus;



	if (!sched_smp_initialized)

		return NOTIFY_DONE;



	switch (action) {

	case CPU_DOWN_PREPARE:

		rcu_read_lock_sched();
@@ -7216,10 +7208,6 @@ void __init sched_init_smp(void) 
		cpumask_set_cpu(smp_processor_id(), non_isolated_cpus);

	mutex_unlock(&sched_domains_mutex);



	hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);

	hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);

	hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);



	init_hrtick();



	/* Move init over to a non-isolated CPU */
@@ -7230,7 +7218,32 @@ void __init sched_init_smp(void) 


	init_sched_rt_class();

	init_sched_dl_class();

	sched_smp_initialized = true;

}



static int __init migration_init(void)

{

	void *cpu = (void *)(long)smp_processor_id();

	int err;



	/* Initialize migration for the boot CPU */

	err = migration_call(&migration_notifier, CPU_UP_PREPARE, cpu);

	BUG_ON(err == NOTIFY_BAD);

	migration_call(&migration_notifier, CPU_ONLINE, cpu);

	register_cpu_notifier(&migration_notifier);



	/* Register cpu active notifiers */

	cpu_notifier(sched_cpu_active, CPU_PRI_SCHED_ACTIVE);

	cpu_notifier(sched_cpu_inactive, CPU_PRI_SCHED_INACTIVE);



	hotcpu_notifier(sched_domains_numa_masks_update, CPU_PRI_SCHED_ACTIVE);

	hotcpu_notifier(cpuset_cpu_active, CPU_PRI_CPUSET_ACTIVE);

	hotcpu_notifier(cpuset_cpu_inactive, CPU_PRI_CPUSET_INACTIVE);



	return 0;

}

early_initcall(migration_init);



#else

void __init sched_init_smp(void)

{