Install the callbacks via the state machine and let the core invoke the callbacks on the already online CPUs.
Cc: [email protected] Signed-off-by: Sebastian Andrzej Siewior <[email protected]> Signed-off-by: Thomas Gleixner <[email protected]> --- arch/x86/kernel/msr.c | 56 +++++++++------------------------------------- include/linux/cpuhotplug.h | 1 + 2 files changed, 11 insertions(+), 46 deletions(-) diff --git a/arch/x86/kernel/msr.c b/arch/x86/kernel/msr.c index 7f3550acde1b..43a125b5c5dc 100644 --- a/arch/x86/kernel/msr.c +++ b/arch/x86/kernel/msr.c @@ -180,7 +180,7 @@ static const struct file_operations msr_fops = { .compat_ioctl = msr_ioctl, }; -static int msr_device_create(int cpu) +static int msr_device_create(unsigned int cpu) { struct device *dev; @@ -189,34 +189,12 @@ static int msr_device_create(int cpu) return PTR_ERR_OR_ZERO(dev); } -static void msr_device_destroy(int cpu) +static int msr_device_destroy(unsigned int cpu) { device_destroy(msr_class, MKDEV(MSR_MAJOR, cpu)); + return 0; } -static int msr_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 = msr_device_create(cpu); - break; - case CPU_UP_CANCELED: - case CPU_UP_CANCELED_FROZEN: - case CPU_DEAD: - msr_device_destroy(cpu); - break; - } - return notifier_from_errno(err); -} - -static struct notifier_block __refdata msr_class_cpu_notifier = { - .notifier_call = msr_class_cpu_callback, -}; - static char *msr_devnode(struct device *dev, umode_t *mode) { return kasprintf(GFP_KERNEL, "cpu/%u/msr", MINOR(dev->devt)); @@ -224,8 +202,7 @@ static char *msr_devnode(struct device *dev, umode_t *mode) static int __init msr_init(void) { - int i, err = 0; - i = 0; + int err; if (__register_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr", &msr_fops)) { pr_err("unable to get major %d for msr\n", MSR_MAJOR); @@ -239,23 +216,16 @@ static int __init msr_init(void) } msr_class->devnode = msr_devnode; - cpu_notifier_register_begin(); - for_each_online_cpu(i) { - err = msr_device_create(i); - if (err != 0) - goto out_class; - } - __register_hotcpu_notifier(&msr_class_cpu_notifier); - cpu_notifier_register_done(); + err = cpuhp_setup_state(CPUHP_X86_MSR_PREPARE, "x86/msr:prepare", + msr_device_create, msr_device_destroy); + if (err) + goto out_class; err = 0; goto out; out_class: - i = 0; - for_each_online_cpu(i) - msr_device_destroy(i); - cpu_notifier_register_done(); + cpuhp_remove_state(CPUHP_X86_MSR_PREPARE); class_destroy(msr_class); out_chrdev: __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); @@ -265,15 +235,9 @@ static int __init msr_init(void) static void __exit msr_exit(void) { - int cpu = 0; - - cpu_notifier_register_begin(); - for_each_online_cpu(cpu) - msr_device_destroy(cpu); class_destroy(msr_class); __unregister_chrdev(MSR_MAJOR, 0, NR_CPUS, "cpu/msr"); - __unregister_hotcpu_notifier(&msr_class_cpu_notifier); - cpu_notifier_register_done(); + cpuhp_remove_state(CPUHP_X86_MSR_PREPARE); } module_init(msr_init); diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index 2f9e083791c4..6506dce8343a 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -61,6 +61,7 @@ enum cpuhp_state { CPUHP_TOPOLOGY_PREPARE, CPUHP_X86_THERM_PREPARE, CPUHP_X86_CPUID_PREPARE, + CPUHP_X86_MSR_PREPARE, CPUHP_TIMERS_DEAD, CPUHP_NOTF_ERR_INJ_PREPARE, CPUHP_MIPS_SOC_PREPARE, -- 2.10.2
