Prevent access to custom login page for logged in users

by

You should redirect as early as possible. The best hook for this is template_redirect. Check for 2 conditions – if the page is ‘login’ and user is logged in:

function redirect_login_page() {

    if( is_page( 'login' ) && is_user_logged_in() ) {
        wp_redirect( home_url() );
        exit;
    }

}
add_action( 'template_redirect', 'redirect_login_page' );