How do I make jQuery wait for an Ajax call to finish before it returns?

I have a server side function that requires login. If the user is logged in the function will return 1 on success. If not, the function will return the login-page.

I want to call the function using Ajax and jQuery. What I do is submit the request with an ordinary link, with a click-function applied on it. If the user is not logged in or the function fails, I want the Ajax-call to return true, so that the href triggers.

However, when I use the following code, the function exits before the Ajax call is done.

How can I redirect the user gracefully to the loginpage?

$(".my_link").click(
    function(){
    $.ajax({
        url: $(this).attr('href'),
        type: 'GET',
        cache: false,
        timeout: 30000,
        error: function(){
            return true;
        },
        success: function(msg){ 
            if (parseFloat(msg)){
                return false;
            } else {
                return true;
            }
        }
    });
});