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x86/msr: Convert to hotplug state machine
Install the callbacks via the state machine and let the core invoke the callbacks on the already online CPUs. Move the callbacks to online/offline as there is no point in having the files around before the cpu is online and until its completely gone. [ tglx: Move the callbacks to online/offline ] Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: rt@linuxtronix.de Link: http://lkml.kernel.org/r/20161117183541.8588-4-bigeasy@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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@ -44,6 +44,7 @@
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#include <asm/msr.h>
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#include <asm/msr.h>
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static struct class *msr_class;
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static struct class *msr_class;
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static enum cpuhp_state cpuhp_msr_state;
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static ssize_t msr_read(struct file *file, char __user *buf,
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static ssize_t msr_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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size_t count, loff_t *ppos)
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@ -180,7 +181,7 @@ static const struct file_operations msr_fops = {
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.compat_ioctl = msr_ioctl,
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.compat_ioctl = msr_ioctl,
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};
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};
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static int msr_device_create(int cpu)
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static int msr_device_create(unsigned int cpu)
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{
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{
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struct device *dev;
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struct device *dev;
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@ -189,34 +190,12 @@ static int msr_device_create(int cpu)
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return PTR_ERR_OR_ZERO(dev);
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return PTR_ERR_OR_ZERO(dev);
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}
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}
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static void msr_device_destroy(int cpu)
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static int msr_device_destroy(unsigned int cpu)
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{
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{
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device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
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device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu));
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return 0;
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}
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}
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static int msr_class_cpu_callback(struct notifier_block *nfb,
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unsigned long action, void *hcpu)
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{
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unsigned int cpu = (unsigned long)hcpu;
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int err = 0;
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switch (action) {
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case CPU_UP_PREPARE:
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err = msr_device_create(cpu);
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break;
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case CPU_UP_CANCELED:
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case CPU_UP_CANCELED_FROZEN:
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case CPU_DEAD:
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msr_device_destroy(cpu);
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break;
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}
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return notifier_from_errno(err);
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}
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static struct notifier_block __refdata msr_class_cpu_notifier = {
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.notifier_call = msr_class_cpu_callback,
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};
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static char *msr_devnode(struct device *dev, umode_t *mode)
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static char *msr_devnode(struct device *dev, umode_t *mode)
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{
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{
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return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
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return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt));
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@ -224,13 +203,11 @@ static char *msr_devnode(struct device *dev, umode_t *mode)
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static int __init msr_init(void)
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static int __init msr_init(void)
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{
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{
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int i, err = 0;
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int err;
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i = 0;
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if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) {
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if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) {
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pr_err("unable to get major %d for msr\n", MSR_MAJOR);
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pr_err("unable to get major %d for msr\n", MSR_MAJOR);
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err = -EBUSY;
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return -EBUSY;
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goto out;
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}
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}
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msr_class = class_create(THIS_MODULE, "msr");
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msr_class = class_create(THIS_MODULE, "msr");
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if (IS_ERR(msr_class)) {
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if (IS_ERR(msr_class)) {
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@ -239,44 +216,28 @@ static int __init msr_init(void)
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}
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}
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msr_class->devnode = msr_devnode;
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msr_class->devnode = msr_devnode;
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cpu_notifier_register_begin();
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err = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/msr:online",
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for_each_online_cpu(i) {
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msr_device_create, msr_device_destroy);
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err = msr_device_create(i);
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if (err < 0)
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if (err != 0)
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goto out_class;
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goto out_class;
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}
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cpuhp_msr_state = err;
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__register_hotcpu_notifier(&msr_class_cpu_notifier);
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return 0;
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cpu_notifier_register_done();
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err = 0;
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goto out;
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out_class:
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out_class:
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i = 0;
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cpuhp_remove_state(cpuhp_msr_state);
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for_each_online_cpu(i)
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msr_device_destroy(i);
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cpu_notifier_register_done();
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class_destroy(msr_class);
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class_destroy(msr_class);
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out_chrdev:
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out_chrdev:
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__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
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__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
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out:
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return err;
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return err;
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}
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}
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module_init(msr_init);
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static void __exit msr_exit(void)
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static void __exit msr_exit(void)
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{
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{
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int cpu = 0;
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cpuhp_remove_state(cpuhp_msr_state);
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cpu_notifier_register_begin();
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for_each_online_cpu(cpu)
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msr_device_destroy(cpu);
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class_destroy(msr_class);
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class_destroy(msr_class);
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__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
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__unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr");
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__unregister_hotcpu_notifier(&msr_class_cpu_notifier);
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cpu_notifier_register_done();
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}
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}
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module_init(msr_init);
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module_exit(msr_exit)
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module_exit(msr_exit)
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MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
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MODULE_AUTHOR("H. Peter Anvin <hpa@zytor.com>");
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