class_simple_device_remove(MKDEV(CPUID_MAJOR, cpu));
class_device_destroy(cpuid_class, MKDEV(CPUID_MAJOR, cpu));
static int __devinit cpuid_class_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu){	unsigned int cpu = (unsigned long)hcpu;	switch (action) {	case CPU_ONLINE:		cpuid_class_simple_device_add(cpu);		break;	case CPU_DEAD:		class_simple_device_remove(MKDEV(CPUID_MAJOR, cpu));		break;	}	return NOTIFY_OK;}