--- netmap_generic.c
+++ netmap_generic.c
@@ -319,9 +319,9 @@
  * by netmap to transmit a packet. This usually happens when
  * the NIC notifies the driver that transmission is completed.
  */
-static void
+static void __unused
 generic_mbuf_destructor(struct mbuf *m)
-{
+{	/* kept for documentation; never installed (DF-3427) */
 #ifdef RIG_TRACE
     kprintf("RIG: generic_mbuf_destructor CALLED m=%p "
         "(ABI-incoherent ext_free(ext_arg) entry)\n", m);
@@ -533,6 +533,7 @@
              * ring->avail == 0 || j != k
              */
             tx_ret = generic_xmit_frame(ifp, m, addr, len, ring_nr);
+            kring->tx_pool[j] = NULL;	/* DF-3426 fix */
 #ifdef RIG_TRACE
             if (tx_ret)
                 kprintf("RIG: xmit dispatch FAILED ret=%d j=%u ntc=%u "