Bug 1889 - PointToPointNetDevive: In some cases MacTxDrop trace is not called

RELEASE_NOTES

@@ -62,6 +62,7 @@ Bugs fixed
 - Bug 1882 - int64x64 tests trigger valgrind bug
 - Bug 1883 - IPv6 don't consider the prefix and network when choosing output address
 - Bug 1887 - Point-to-point traces should contain PPP headers
+- Bug 1889 - PointToPointNetDevive: In some cases MacTxDrop trace is not called
 - Bug 1890 - UdpClientTrace: MPEG frame size is squeezed into (insufficient) 16 bit integer
 - Bug 1891 - UdpSocketImpl::GetSockName doesn't return the IPv6 address
 

src/point-to-point/model/point-to-point-net-device.cc

@@ -493,33 +493,26 @@ PointToPointNetDevice::Send (
   m_macTxTrace (packet);
 
   //
-  // If there's a transmission in progress, we enque the packet for later
-  // transmission; otherwise we send it now.
+  // We should enqueue and dequeue the packet to hit the tracing hooks.
   //
-  if (m_txMachineState == READY) 
+  if (m_queue->Enqueue (packet))
     {
-      // 
-      // Even if the transmitter is immediately available, we still enqueue and
-      // dequeue the packet to hit the tracing hooks.
       //
-      if (m_queue->Enqueue (packet) == true)
+      // If the channel is ready for transition we send the packet right now
+      // 
+      if (m_txMachineState == READY)
         {
           packet = m_queue->Dequeue ();
           m_snifferTrace (packet);
           m_promiscSnifferTrace (packet);
           return TransmitStart (packet);
         }
-      else
-        {
-          // Enqueue may fail (overflow)
-          m_macTxDropTrace (packet);
-          return false;
-        }
-    }
-  else
-    {
-      return m_queue->Enqueue (packet);
+      return true;
     }
+
+  // Enqueue may fail (overflow)
+  m_macTxDropTrace (packet);
+  return false;
 }
 
 bool