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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: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: rt@linuxtronix.de
Link: http://lkml.kernel.org/r/20161117183541.8588-3-bigeasy@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Sebastian Andrzej Siewior 2016-11-17 19:35:23 +01:00 committed by Thomas Gleixner
parent 33d97302eb
commit 8c07b494ab
2 changed files with 12 additions and 53 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

64
arch/x86/kernel/cpuid.c
View File

@ -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)
goto out_class;
}
__register_hotcpu_notifier(&cpuid_class_cpu_notifier);
cpu_notifier_register_done();
err = cpuhp_setup_state(CPUHP_X86_CPUID_PREPARE, "x86/cpuid:prepare",
cpuid_device_create, cpuid_device_destroy);
if (err)
goto out_class;
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);

1
include/linux/cpuhotplug.h
View File

@ -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,