vcl: epoll out deq notifications only if fifo exists

Type: fix

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: Ia37d8474224f6074826c9ffb82feb919b2ef52f7
diff --git a/src/vcl/vppcom.c b/src/vcl/vppcom.c
index 80f0ad7..b576e1a 100644
--- a/src/vcl/vppcom.c
+++ b/src/vcl/vppcom.c
@@ -2658,10 +2658,13 @@
       s->vep.et_mask = VEP_DEFAULT_ET_MASK;
       s->vep.ev = *event;
       txf = vcl_session_is_ct (s) ? s->ct_tx_fifo : s->tx_fifo;
-      if (event->events & EPOLLOUT)
-	svm_fifo_add_want_deq_ntf (txf, SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL);
-      else
-	svm_fifo_del_want_deq_ntf (txf, SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL);
+      if (txf)
+	{
+	  if (event->events & EPOLLOUT)
+	    svm_fifo_add_want_deq_ntf (txf, SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL);
+	  else
+	    svm_fifo_del_want_deq_ntf (txf, SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL);
+	}
       VDBG (1, "EPOLL_CTL_MOD: vep_sh %u, sh %u, events 0x%x, data 0x%llx!",
 	    vep_handle, session_handle, event->events, event->data.u64);
       break;