perf: Specialize perf_event_exit_task()

	 * Do destroy all inherited groups, we don't care about those

	 * and being thorough is better.

	 */

	perf_remove_from_context(child_event, !!child_event->parent);

	raw_spin_lock_irq(&child_ctx->lock);

	WARN_ON_ONCE(child_ctx->is_active);

	if (!!child_event->parent)

		perf_group_detach(child_event);

	list_del_event(child_event, child_ctx);

	raw_spin_unlock_irq(&child_ctx->lock);

	/*

	 * It can happen that the parent exits first, and has events

{

	struct perf_event *child_event, *next;

	struct perf_event_context *child_ctx, *clone_ctx = NULL;

	unsigned long flags;

	if (likely(!child->perf_event_ctxp[ctxn]))

		return;

	local_irq_save(flags);

	local_irq_disable();

	WARN_ON_ONCE(child != current);

	/*

	 * We can't reschedule here because interrupts are disabled,

	 * and either child is current or it is a task that can't be

	 * scheduled, so we are now safe from rescheduling changing

	 * our context.

	 * and child must be current.

	 */

	child_ctx = rcu_dereference_raw(child->perf_event_ctxp[ctxn]);

	 */

	clone_ctx = unclone_ctx(child_ctx);

	update_context_time(child_ctx);

	raw_spin_unlock_irqrestore(&child_ctx->lock, flags);

	raw_spin_unlock_irq(&child_ctx->lock);

	if (clone_ctx)

		put_ctx(clone_ctx);