static int centrino_target()

in speedstep-centrino.c [422:504]

• 58 lines of code
• 10 McCabe index (conditional complexity)

static int centrino_target(struct cpufreq_policy *policy, unsigned int index)
{
	unsigned int	msr, oldmsr = 0, h = 0, cpu = policy->cpu;
	int			retval = 0;
	unsigned int		j, first_cpu;
	struct cpufreq_frequency_table *op_points;
	cpumask_var_t covered_cpus;

	if (unlikely(!zalloc_cpumask_var(&covered_cpus, GFP_KERNEL)))
		return -ENOMEM;

	if (unlikely(per_cpu(centrino_model, cpu) == NULL)) {
		retval = -ENODEV;
		goto out;
	}

	first_cpu = 1;
	op_points = &per_cpu(centrino_model, cpu)->op_points[index];
	for_each_cpu(j, policy->cpus) {
		int good_cpu;

		/*
		 * Support for SMP systems.
		 * Make sure we are running on CPU that wants to change freq
		 */
		if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
			good_cpu = cpumask_any_and(policy->cpus,
						   cpu_online_mask);
		else
			good_cpu = j;

		if (good_cpu >= nr_cpu_ids) {
			pr_debug("couldn't limit to CPUs in this domain\n");
			retval = -EAGAIN;
			if (first_cpu) {
				/* We haven't started the transition yet. */
				goto out;
			}
			break;
		}

		msr = op_points->driver_data;

		if (first_cpu) {
			rdmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, &oldmsr, &h);
			if (msr == (oldmsr & 0xffff)) {
				pr_debug("no change needed - msr was and needs "
					"to be %x\n", oldmsr);
				retval = 0;
				goto out;
			}

			first_cpu = 0;
			/* all but 16 LSB are reserved, treat them with care */
			oldmsr &= ~0xffff;
			msr &= 0xffff;
			oldmsr |= msr;
		}

		wrmsr_on_cpu(good_cpu, MSR_IA32_PERF_CTL, oldmsr, h);
		if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY)
			break;

		cpumask_set_cpu(j, covered_cpus);
	}

	if (unlikely(retval)) {
		/*
		 * We have failed halfway through the frequency change.
		 * We have sent callbacks to policy->cpus and
		 * MSRs have already been written on coverd_cpus.
		 * Best effort undo..
		 */

		for_each_cpu(j, covered_cpus)
			wrmsr_on_cpu(j, MSR_IA32_PERF_CTL, oldmsr, h);
	}
	retval = 0;

out:
	free_cpumask_var(covered_cpus);
	return retval;
}