Merge "perf/core: Fix crash in perf_event_read()"

static int perf_event_read(struct perf_event *event, bool group)

{

	int ret = 0;

	int event_cpu, ret = 0;

	/*

	 * If event is enabled and currently active on a CPU, update the

	 * value in the event structure:

	 */

	event_cpu = READ_ONCE(event->oncpu);

	if (event->state == PERF_EVENT_STATE_ACTIVE &&

						!cpu_isolated(event->oncpu)) {

						!cpu_isolated(event_cpu)) {

		struct perf_read_data data = {

			.event = event,

			.group = group,

			.ret = 0,

		};

		if ((unsigned int)event_cpu >= nr_cpu_ids)

			return 0;

		if (!event->attr.exclude_idle ||

					!per_cpu(is_idle, event->oncpu)) {

			smp_call_function_single(event->oncpu,

					!per_cpu(is_idle, event_cpu)) {

			smp_call_function_single(event_cpu,

				__perf_event_read, &data, 1);

			ret = data.ret;

		}