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Commit 8c07b494 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Thomas Gleixner
Browse files

x86/cpuid: Convert to hotplug state machine 



Install the callbacks via the state machine and let the core invoke
the callbacks on the already online CPUs.

Signed-off-by: default avatarSebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: rt@linuxtronix.de
Link: http://lkml.kernel.org/r/20161117183541.8588-3-bigeasy@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 33d97302

arch/x86/kernel/cpuid.c

+11 −53
Original line number Diff line number Diff line
@@ -115,7 +115,7 @@ static const struct file_operations cpuid_fops = { 
	.open = cpuid_open,

};



static int cpuid_device_create(int cpu)

static int cpuid_device_create(unsigned int cpu)

{

	struct device *dev;
@@ -124,35 +124,12 @@ static int cpuid_device_create(int cpu) 
	return PTR_ERR_OR_ZERO(dev);

}



static void cpuid_device_destroy(int cpu)

static int cpuid_device_destroy(unsigned int cpu)

{

	device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));

	return 0;

}



static int cpuid_class_cpu_callback(struct notifier_block *nfb,

				    unsigned long action, void *hcpu)

{

	unsigned int cpu = (unsigned long)hcpu;

	int err = 0;



	switch (action) {

	case CPU_UP_PREPARE:

		err = cpuid_device_create(cpu);

		break;

	case CPU_UP_CANCELED:

	case CPU_UP_CANCELED_FROZEN:

	case CPU_DEAD:

		cpuid_device_destroy(cpu);

		break;

	}

	return notifier_from_errno(err);

}



static struct notifier_block cpuid_class_cpu_notifier =

{

	.notifier_call = cpuid_class_cpu_callback,

};



static char *cpuid_devnode(struct device *dev, umode_t *mode)

{

	return kasprintf(GFP_KERNEL, "cpu/%u/cpuid", MINOR(dev->devt));
@@ -160,15 +137,13 @@ static char *cpuid_devnode(struct device *dev, umode_t *mode) 


static int __init cpuid_init(void)

{

	int i, err = 0;

	i = 0;

	int err;



	if (__register_chrdev(CPUID_MAJOR, 0, NR_CPUS,

			      "cpu/cpuid", &cpuid_fops)) {

		printk(KERN_ERR "cpuid: unable to get major %d for cpuid\n",

		       CPUID_MAJOR);

		err = -EBUSY;

		goto out;

		return -EBUSY;

	}

	cpuid_class = class_create(THIS_MODULE, "cpuid");

	if (IS_ERR(cpuid_class)) {
@@ -177,42 +152,25 @@ static int __init cpuid_init(void) 
	}

	cpuid_class->devnode = cpuid_devnode;



	cpu_notifier_register_begin();

	for_each_online_cpu(i) {

		err = cpuid_device_create(i);

		if (err != 0)

	err = cpuhp_setup_state(CPUHP_X86_CPUID_PREPARE, "x86/cpuid:prepare",

				cpuid_device_create, cpuid_device_destroy);

	if (err)

		goto out_class;

	}

	__register_hotcpu_notifier(&cpuid_class_cpu_notifier);

	cpu_notifier_register_done();



	err = 0;

	goto out;

	return 0;



out_class:

	i = 0;

	for_each_online_cpu(i) {

		cpuid_device_destroy(i);

	}

	cpu_notifier_register_done();

	class_destroy(cpuid_class);

out_chrdev:

	__unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");

out:

	return err;

}



static void __exit cpuid_exit(void)

{

	int cpu = 0;



	cpu_notifier_register_begin();

	for_each_online_cpu(cpu)

		cpuid_device_destroy(cpu);

	cpuhp_remove_state(CPUHP_X86_CPUID_PREPARE);

	class_destroy(cpuid_class);

	__unregister_chrdev(CPUID_MAJOR, 0, NR_CPUS, "cpu/cpuid");

	__unregister_hotcpu_notifier(&cpuid_class_cpu_notifier);

	cpu_notifier_register_done();

}



module_init(cpuid_init);

include/linux/cpuhotplug.h

+1 −0
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ enum cpuhp_state { 
	CPUHP_BLK_MQ_PREPARE,

	CPUHP_NET_FLOW_PREPARE,

	CPUHP_TOPOLOGY_PREPARE,

	CPUHP_X86_CPUID_PREPARE,

	CPUHP_TIMERS_DEAD,

	CPUHP_NOTF_ERR_INJ_PREPARE,

	CPUHP_MIPS_SOC_PREPARE,