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Commit f2785ddb authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

sched/hotplug: Move migration CPU_DYING to sched_cpu_dying() 



Remove the hotplug notifier and make it an explicit state.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPeter Zijlstra <peterz@infradead.org>
Cc: rt@linutronix.de
Link: http://lkml.kernel.org/r/20160310120025.502222097@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 7d976699

include/linux/cpu.h

+0 −2
Original line number Diff line number Diff line
@@ -59,9 +59,7 @@ struct notifier_block; 
 * CPU notifier priorities.

 */

enum {

	/* migration should happen before other stuff but after perf */

	CPU_PRI_PERF		= 20,

	CPU_PRI_MIGRATION	= 10,



	/* bring up workqueues before normal notifiers and down after */

	CPU_PRI_WORKQUEUE_UP	= 5,

include/linux/sched.h

+6 −0
Original line number Diff line number Diff line
@@ -376,6 +376,12 @@ extern int sched_cpu_starting(unsigned int cpu); 
extern int sched_cpu_activate(unsigned int cpu);

extern int sched_cpu_deactivate(unsigned int cpu);



#ifdef CONFIG_HOTPLUG_CPU

extern int sched_cpu_dying(unsigned int cpu);

#else

# define sched_cpu_dying	NULL

#endif



extern void sched_show_task(struct task_struct *p);



#ifdef CONFIG_LOCKUP_DETECTOR

kernel/cpu.c

+1 −1
Original line number Diff line number Diff line
@@ -1223,7 +1223,7 @@ static struct cpuhp_step cpuhp_ap_states[] = { 
	[CPUHP_AP_SCHED_STARTING] = {

		.name			= "sched:starting",

		.startup		= sched_cpu_starting,

		.teardown		= NULL,

		.teardown		= sched_cpu_dying,

	},

	/*

	 * Low level startup/teardown notifiers. Run with interrupts

kernel/sched/core.c

+22 −50
Original line number Diff line number Diff line
@@ -5411,51 +5411,6 @@ static void set_rq_offline(struct rq *rq) 
	}

}



/*

 * migration_call - callback that gets triggered when a CPU is added.

 * Here we can start up the necessary migration thread for the new CPU.

 */

static int

migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)

{

	int cpu = (long)hcpu;

	unsigned long flags;

	struct rq *rq = cpu_rq(cpu);



	switch (action & ~CPU_TASKS_FROZEN) {



#ifdef CONFIG_HOTPLUG_CPU

	case CPU_DYING:

		sched_ttwu_pending();

		/* Update our root-domain */

		raw_spin_lock_irqsave(&rq->lock, flags);

		if (rq->rd) {

			BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));

			set_rq_offline(rq);

		}

		migrate_tasks(rq);

		BUG_ON(rq->nr_running != 1); /* the migration thread */

		raw_spin_unlock_irqrestore(&rq->lock, flags);

		calc_load_migrate(rq);

		break;

#endif

	}



	update_max_interval();



	return NOTIFY_OK;

}



/*

 * Register at high priority so that task migration (migrate_all_tasks)

 * happens before everything else.  This has to be lower priority than

 * the notifier in the perf_event subsystem, though.

 */

static struct notifier_block migration_notifier = {

	.notifier_call = migration_call,

	.priority = CPU_PRI_MIGRATION,

};



static void set_cpu_rq_start_time(unsigned int cpu)

{

	struct rq *rq = cpu_rq(cpu);
@@ -7158,6 +7113,28 @@ int sched_cpu_starting(unsigned int cpu) 
	return 0;

}



#ifdef CONFIG_HOTPLUG_CPU

int sched_cpu_dying(unsigned int cpu)

{

	struct rq *rq = cpu_rq(cpu);

	unsigned long flags;



	/* Handle pending wakeups and then migrate everything off */

	sched_ttwu_pending();

	raw_spin_lock_irqsave(&rq->lock, flags);

	if (rq->rd) {

		BUG_ON(!cpumask_test_cpu(cpu, rq->rd->span));

		set_rq_offline(rq);

	}

	migrate_tasks(rq);

	BUG_ON(rq->nr_running != 1);

	raw_spin_unlock_irqrestore(&rq->lock, flags);

	calc_load_migrate(rq);

	update_max_interval();

	return 0;

}

#endif



void __init sched_init_smp(void)

{

	cpumask_var_t non_isolated_cpus;
@@ -7194,12 +7171,7 @@ void __init sched_init_smp(void) 


static int __init migration_init(void)

{

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



	sched_rq_cpu_starting(smp_processor_id());

	migration_call(&migration_notifier, CPU_ONLINE, cpu);

	register_cpu_notifier(&migration_notifier);



	return 0;

}

early_initcall(migration_init);