static ssize_t cpu_configure_store()

in kernel/smp.c [1055:1118]

• 62 lines of code
• 20 McCabe index (conditional complexity)

static ssize_t cpu_configure_store(struct device *dev,
				   struct device_attribute *attr,
				   const char *buf, size_t count)
{
	struct pcpu *pcpu;
	int cpu, val, rc, i;
	char delim;

	if (sscanf(buf, "%d %c", &val, &delim) != 1)
		return -EINVAL;
	if (val != 0 && val != 1)
		return -EINVAL;
	cpus_read_lock();
	mutex_lock(&smp_cpu_state_mutex);
	rc = -EBUSY;
	/* disallow configuration changes of online cpus and cpu 0 */
	cpu = dev->id;
	cpu = smp_get_base_cpu(cpu);
	if (cpu == 0)
		goto out;
	for (i = 0; i <= smp_cpu_mtid; i++)
		if (cpu_online(cpu + i))
			goto out;
	pcpu = pcpu_devices + cpu;
	rc = 0;
	switch (val) {
	case 0:
		if (pcpu->state != CPU_STATE_CONFIGURED)
			break;
		rc = sclp_core_deconfigure(pcpu->address >> smp_cpu_mt_shift);
		if (rc)
			break;
		for (i = 0; i <= smp_cpu_mtid; i++) {
			if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
				continue;
			pcpu[i].state = CPU_STATE_STANDBY;
			smp_cpu_set_polarization(cpu + i,
						 POLARIZATION_UNKNOWN);
		}
		topology_expect_change();
		break;
	case 1:
		if (pcpu->state != CPU_STATE_STANDBY)
			break;
		rc = sclp_core_configure(pcpu->address >> smp_cpu_mt_shift);
		if (rc)
			break;
		for (i = 0; i <= smp_cpu_mtid; i++) {
			if (cpu + i >= nr_cpu_ids || !cpu_present(cpu + i))
				continue;
			pcpu[i].state = CPU_STATE_CONFIGURED;
			smp_cpu_set_polarization(cpu + i,
						 POLARIZATION_UNKNOWN);
		}
		topology_expect_change();
		break;
	default:
		break;
	}
out:
	mutex_unlock(&smp_cpu_state_mutex);
	cpus_read_unlock();
	return rc ? rc : count;
}