+
+ /*
+ * from_backend calls term_out, but it can also be called from
+ * the ldisc if the ldisc is called _within_ term_out. So we
+ * have to guard against re-entrancy - if from_backend is
+ * called recursively like this, it will simply add data to the
+ * end of the buffer term_out is in the process of working
+ * through.
+ */
+ int in_term_out;