DETACH_GROUP
detach_flags |= DETACH_GROUP | DETACH_CHILD;
detach_flags |= DETACH_GROUP | DETACH_REVOKE;
__perf_remove_from_context(event, cpuctx, ctx, (void *)DETACH_GROUP);
if (flags & DETACH_GROUP)
perf_remove_from_context(event, DETACH_GROUP|DETACH_DEAD);
perf_remove_from_context(child, DETACH_GROUP | DETACH_CHILD);