6loWPAN: Fixes hang in loopback test.

net/sixlowpan/sixlowpan_framelist.c

@@ -511,19 +511,16 @@ int sixlowpan_queue_frames(FAR struct ieee802154_driver_s *ieee,
           qhead->io_pktlen += iob->io_len;
         }
 
-      /* Submit all of the fragments to the MAC */
+      /* Submit all of the fragments to the MAC.  We send all frames back-
+       * to-back like this to eliminate any possible condition where some
+       * frame which is not a fragment from this sequence from intervening.
+       */
 
-      while (qhead != NULL)
-      {
-        iob   = qhead;
-        qhead = iob->io_flink;
-
-        ret = sixlowpan_frame_submit(ieee, &meta, iob);
-        if (ret < 0)
-          {
-            nerr("ERROR: sixlowpan_frame_submit() failed: %d\n", ret);
-          }
-      }
+      ret = sixlowpan_frame_submit(ieee, &meta, qhead);
+      if (ret < 0)
+        {
+          nerr("ERROR: sixlowpan_frame_submit() failed: %d\n", ret);
+        }
 
       /* Update the datagram TAG value */
 

net/sixlowpan/sixlowpan_framer.c

@@ -66,33 +66,6 @@
  * Public Functions
  ****************************************************************************/
 
-/****************************************************************************
- * Name: sixlowpan_addrlen
- *
- * Description:
- *   Return the address length associated with a 2-bit address mode
- *
- * Input parameters:
- *   addrmode - The address mode
- *
- * Returned Value:
- *   The address length associated with the address mode.
- *
- ****************************************************************************/
-
-static inline uint8_t sixlowpan_addrlen(uint8_t addrmode)
-{
-  switch (addrmode)
-    {
-    case FRAME802154_SHORTADDRMODE:  /* 16-bit address */
-      return 2;
-    case FRAME802154_LONGADDRMODE:   /* 64-bit address */
-      return 8;
-    default:
-      return 0;
-    }
-}
-
 /****************************************************************************
  * Name: sixlowpan_addrnull
  *