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Commit 98f8cdce authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

cpu/hotplug: Add sysfs state interface 



Add a sysfs interface so we can actually see in which state the cpus are in.

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/20160226182340.942257522@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent af1f4045

kernel/cpu.c

+100 −0
Original line number Diff line number Diff line
@@ -56,6 +56,7 @@ struct cpuhp_step { 
	bool		skip_onerr;

};



static DEFINE_MUTEX(cpuhp_state_mutex);

static struct cpuhp_step cpuhp_bp_states[];

static struct cpuhp_step cpuhp_ap_states[];
@@ -955,6 +956,105 @@ static struct cpuhp_step cpuhp_ap_states[] = { 
	},

};



static bool cpuhp_is_ap_state(enum cpuhp_state state)

{

	return (state > CPUHP_AP_OFFLINE && state < CPUHP_AP_ONLINE);

}



static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)

{

	struct cpuhp_step *sp;



	sp = cpuhp_is_ap_state(state) ? cpuhp_ap_states : cpuhp_bp_states;

	return sp + state;

}



#if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)

static ssize_t show_cpuhp_state(struct device *dev,

				struct device_attribute *attr, char *buf)

{

	struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);



	return sprintf(buf, "%d\n", st->state);

}

static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);



static ssize_t show_cpuhp_target(struct device *dev,

				 struct device_attribute *attr, char *buf)

{

	struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);



	return sprintf(buf, "%d\n", st->target);

}

static DEVICE_ATTR(target, 0444, show_cpuhp_target, NULL);



static struct attribute *cpuhp_cpu_attrs[] = {

	&dev_attr_state.attr,

	&dev_attr_target.attr,

	NULL

};



static struct attribute_group cpuhp_cpu_attr_group = {

	.attrs = cpuhp_cpu_attrs,

	.name = "hotplug",

	NULL

};



static ssize_t show_cpuhp_states(struct device *dev,

				 struct device_attribute *attr, char *buf)

{

	ssize_t cur, res = 0;

	int i;



	mutex_lock(&cpuhp_state_mutex);

	for (i = 0; i <= CPUHP_ONLINE; i++) {

		struct cpuhp_step *sp = cpuhp_get_step(i);



		if (sp->name) {

			cur = sprintf(buf, "%3d: %s\n", i, sp->name);

			buf += cur;

			res += cur;

		}

	}

	mutex_unlock(&cpuhp_state_mutex);

	return res;

}

static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL);



static struct attribute *cpuhp_cpu_root_attrs[] = {

	&dev_attr_states.attr,

	NULL

};



static struct attribute_group cpuhp_cpu_root_attr_group = {

	.attrs = cpuhp_cpu_root_attrs,

	.name = "hotplug",

	NULL

};



static int __init cpuhp_sysfs_init(void)

{

	int cpu, ret;



	ret = sysfs_create_group(&cpu_subsys.dev_root->kobj,

				 &cpuhp_cpu_root_attr_group);

	if (ret)

		return ret;



	for_each_possible_cpu(cpu) {

		struct device *dev = get_cpu_device(cpu);



		if (!dev)

			continue;

		ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group);

		if (ret)

			return ret;

	}

	return 0;

}

device_initcall(cpuhp_sysfs_init);

#endif



/*

 * cpu_bit_bitmap[] is a special, "compressed" data structure that

 * represents all NR_CPUS bits binary values of 1<<nr.