my $root = {};
_create_node ($root,"pp1","first");
_create_node ($root->{pp1},"ppp1","second");
_create_node ($root->{ppp1},"pppp1","third");
_create_node ($root->{pppp1},"ppppp1","root");

my $infos = _go_through('p1');
#my $infos = _go_through($root); # doesn't work either

print Dumper $infos;

sub _create_node
  {
#    no strict 'refs';
    my ($node,$parent,$node_info) = @_;
    @{$node}{qw/parent info/} = ($parent,$node_info);
  }

sub _go_through
  {
    my ($node) = @_;
    return "" unless defined ${$node}{"info"};
    my @info_nodes;
    while (${$node}{"info"} ne "root"){
      push @info_nodes, (${$node}{"info"});
      $node = ${$node}{"parent"};  ## Line 33
    }
    return \@info_nodes;
  }