Inline::C hash access

[fireartist]

I've not attempted to use Inline::C since my last flirt, 3 years ago (Inline::C - object accessor failure) and my C knowledge is still almost non-existent.
However, I've got some methods which are called hundreds of thousands of times, and I'm trying to get the runtime down - and I'm hoping someone will offer to translate this particular one into Inline::C for me, so I can see if it makes a difference.
I've tried lots of variations of dealing with the SV** returned by hv_fetch() - but to be honest, I don't have a clue what I'm doing!
Here's the original perl method:
(btw - in the c-code, it would be sufficient to just check exists $self->{parent} rather than defined)

sub root {
    my $self = shift;

    while ( defined ( my $parent = $self->{parent} ) ) {
        $self = $parent;
    }

    return $self;
}