get_posts in cred_save

function calculate_score_save_data_action( $post_id, $form_data ) {

    //the ID of "rate and Approve CRED Form"
    if ( $form_data['id'] == 1205 ) {

        //get the current exam post
        $post = get_post($post_id);

        //get the current exams post id
        $post_in_loop_id = $post->ID;
        $post_author_id = get_post_field( 'post_author', $post_id );


        //get current exmas possible score (that numeric value is already set in the exam)
        $post_possible_exam_score = get_post_meta( $post_id, 'wpcf-possible-maximal-score-for-this-exam', true);

        // get all questions of this exam (childs of Exam)
        $all_questions = get_posts(array(
            'numberposts'   => -1,
            'post_type'     => 'question',
            'meta_key'      => '_wpcf_belongs_exam_id',
            'meta_value'    => $post_in_loop_id)
        );

        //if it returns some posts
        if( $all_questions ){

            //start the count on 0 for the scores sum later on (each question/answer has his "is" and "should" points)
            $single_question_possible_score_sum = 0;
            $single_question_real_score_sum = 0;

            //now get the single answers
            foreach( $all_questions as $single_question ){

                //get each questions post data
                $single_question_post = get_post($single_question);
                //get each ID
                $single_question_id = $single_question_post->ID;

                //get value of possible scores
                $single_question_possible_score_is = get_post_meta($single_question_id, 'wpcf-possible-maximum-score', true );
                //get value if real scores
                $single_question_real_score_is = get_post_meta($single_question_id, 'wpcf-real-maximum-score', true);
                //we need to sum this up BEFORE the if is closed and BEFORE the foreach is closed
                //Sum the possible scores of all questions
                $single_question_possible_score_sum+= $single_question_possible_score_is;
                //Sum the real scores of all questions
                $single_question_real_score_sum+= $single_question_real_score_is;
            }
        }

        //Update the Exams real score (total of all questions real score)
        update_post_meta( $post_id, 'wpcf-real-maximal-score-for-this-exam', $single_question_real_score_sum);


    }
}
add_action('cred_save_data', 'calculate_score_save_data_action',10,2);