Merge "sched/fair: prevent possible infinite loop in compute_energy()" into msm-4.14

	int cpu;

	struct cpumask visit_cpus;

	struct sched_group *sg;

	int cpu_count;

	WARN_ON(!eenv->sg_top->sge);

	cpumask_copy(&visit_cpus, sched_group_span(eenv->sg_top));

	/* If a cpu is hotplugged in while we are in this function, it does

	 * not appear in the existing visit_cpus mask which came from the

	 * sched_group pointer of the sched_domain pointed at by sd_ea for

	 * either the prev or next cpu and was dereferenced in

	 * select_energy_cpu_idx.

	 * Since we will dereference sd_scs later as we iterate through the

	 * CPUs we expect to visit, new CPUs can be present which are not in

	 * the visit_cpus mask. Guard this with cpu_count.

	 */

	cpu_count = cpumask_weight(&visit_cpus);

	while (!cpumask_empty(&visit_cpus)) {

		struct sched_group *sg_shared_cap = NULL;

		cpu = cpumask_first(&visit_cpus);

		/*

		 * Is the group utilization affected by cpus outside this

		 * sched_group?

		 * This sd may have groups with cpus which were not present

		 * when we took visit_cpus.

		 */

		sd = rcu_dereference(per_cpu(sd_scs, cpu));

		if (sd && sd->parent)

		for_each_domain(cpu, sd) {

			sg = sd->groups;

			/* Has this sched_domain already been visited? */

			if (sd->child && group_first_cpu(sg) != cpu)

				break;

				calc_sg_energy(eenv);

				/* remove CPUs we have just visited */

				if (!sd->child)

				if (!sd->child) {

					/*

					 * cpu_count here is the number of

					 * cpus we expect to visit in this

					 * calculation. If we race against

					 * hotplug, we can have extra cpus

					 * added to the groups we are

					 * iterating which do not appear in

					 * the visit_cpus mask. In that case

					 * we are not able to calculate energy

					 * without restarting so we will bail

					 * out and use prev_cpu this time.

					 */

					if (!cpu_count)

						return -EINVAL;

					cpumask_xor(&visit_cpus, &visit_cpus, sched_group_span(sg));

					cpu_count--;

				}

				if (cpumask_equal(sched_group_span(sg), sched_group_span(eenv->sg_top)))

					goto next_cpu;