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Commit 931ef163 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

cpu/hotplug: Unpark smpboot threads from the state machine 



Handle the smpboot threads in the state machine.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: Rik van Riel <riel@redhat.com>
Cc: Rafael Wysocki <rafael.j.wysocki@intel.com>
Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Sebastian Siewior <bigeasy@linutronix.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/r/20160226182341.295777684@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 949338e3

include/linux/cpu.h

+1 −6
Original line number Diff line number Diff line
@@ -78,7 +78,7 @@ enum { 
	/* migration should happen before other stuff but after perf */

	CPU_PRI_PERF		= 20,

	CPU_PRI_MIGRATION	= 10,

	CPU_PRI_SMPBOOT		= 9,



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

	CPU_PRI_WORKQUEUE_UP	= 5,

	CPU_PRI_WORKQUEUE_DOWN	= -5,
@@ -172,7 +172,6 @@ static inline void __unregister_cpu_notifier(struct notifier_block *nb) 
}

#endif



void smpboot_thread_init(void);

int cpu_up(unsigned int cpu);

void notify_cpu_starting(unsigned int cpu);

extern void cpu_maps_update_begin(void);
@@ -221,10 +220,6 @@ static inline void cpu_notifier_register_done(void) 
{

}



static inline void smpboot_thread_init(void)

{

}



#endif /* CONFIG_SMP */

extern struct bus_type cpu_subsys;

include/linux/cpuhotplug.h

+1 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ enum cpuhp_state { 
	CPUHP_AP_ONLINE,

	CPUHP_TEARDOWN_CPU,

	CPUHP_CPU_SET_ACTIVE,

	CPUHP_SMPBOOT_THREADS,

	CPUHP_NOTIFY_ONLINE,

	CPUHP_ONLINE_DYN,

	CPUHP_ONLINE_DYN_END		= CPUHP_ONLINE_DYN + 30,

init/main.c

+0 −1
Original line number Diff line number Diff line
@@ -388,7 +388,6 @@ static noinline void __init_refok rest_init(void) 
	int pid;



	rcu_scheduler_starting();

	smpboot_thread_init();

	/*

	 * We need to spawn init first so that it obtains pid 1, however

	 * the init task will end up wanting to create kthreads, which, if

kernel/cpu.c

+5 −34
Original line number Diff line number Diff line
@@ -481,8 +481,6 @@ static int takedown_cpu(unsigned int cpu) 
	else

		synchronize_rcu();



	smpboot_park_threads(cpu);



	/*

	 * Prevent irq alloc/free while the dying cpu reorganizes the

	 * interrupt affinities.
@@ -612,38 +610,6 @@ int cpu_down(unsigned int cpu) 
EXPORT_SYMBOL(cpu_down);

#endif /*CONFIG_HOTPLUG_CPU*/



/*

 * Unpark per-CPU smpboot kthreads at CPU-online time.

 */

static int smpboot_thread_call(struct notifier_block *nfb,

			       unsigned long action, void *hcpu)

{

	int cpu = (long)hcpu;



	switch (action & ~CPU_TASKS_FROZEN) {



	case CPU_DOWN_FAILED:

	case CPU_ONLINE:

		smpboot_unpark_threads(cpu);

		break;



	default:

		break;

	}



	return NOTIFY_OK;

}



static struct notifier_block smpboot_thread_notifier = {

	.notifier_call = smpboot_thread_call,

	.priority = CPU_PRI_SMPBOOT,

};



void smpboot_thread_init(void)

{

	register_cpu_notifier(&smpboot_thread_notifier);

}



/**

 * notify_cpu_starting(cpu) - call the CPU_STARTING notifiers

 * @cpu: cpu that just started
@@ -959,6 +925,11 @@ static struct cpuhp_step cpuhp_bp_states[] = { 
		.startup		= cpuhp_set_cpu_active,

		.teardown		= NULL,

	},

	[CPUHP_SMPBOOT_THREADS] = {

		.name			= "smpboot:threads",

		.startup		= smpboot_unpark_threads,

		.teardown		= smpboot_park_threads,

	},

	[CPUHP_NOTIFY_ONLINE] = {

		.name			= "notify:online",

		.startup		= notify_online,

kernel/smpboot.c

+4 −2
Original line number Diff line number Diff line
@@ -226,7 +226,7 @@ static void smpboot_unpark_thread(struct smp_hotplug_thread *ht, unsigned int cp 
		kthread_unpark(tsk);

}



void smpboot_unpark_threads(unsigned int cpu)

int smpboot_unpark_threads(unsigned int cpu)

{

	struct smp_hotplug_thread *cur;
@@ -235,6 +235,7 @@ void smpboot_unpark_threads(unsigned int cpu) 
		if (cpumask_test_cpu(cpu, cur->cpumask))

			smpboot_unpark_thread(cur, cpu);

	mutex_unlock(&smpboot_threads_lock);

	return 0;

}



static void smpboot_park_thread(struct smp_hotplug_thread *ht, unsigned int cpu)
@@ -245,7 +246,7 @@ static void smpboot_park_thread(struct smp_hotplug_thread *ht, unsigned int cpu) 
		kthread_park(tsk);

}



void smpboot_park_threads(unsigned int cpu)

int smpboot_park_threads(unsigned int cpu)

{

	struct smp_hotplug_thread *cur;
@@ -253,6 +254,7 @@ void smpboot_park_threads(unsigned int cpu) 
	list_for_each_entry_reverse(cur, &hotplug_threads, list)

		smpboot_park_thread(cur, cpu);

	mutex_unlock(&smpboot_threads_lock);

	return 0;

}



static void smpboot_destroy_threads(struct smp_hotplug_thread *ht)