vcl: avoid coalescing dgrams on read

Type: improvement

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: I035f1ef26202bbcf918548cbaa3cdbc17944bf8a
diff --git a/src/vcl/vppcom.c b/src/vcl/vppcom.c
index da7693f..6c85cee 100644
--- a/src/vcl/vppcom.c
+++ b/src/vcl/vppcom.c
@@ -1909,10 +1909,10 @@
 	  e->session_index = s->session_index;
 	}
     }
-  else if (PREDICT_FALSE (rv < n))
+  else if (PREDICT_FALSE (rv < n && !s->is_dgram))
     {
       /* More data enqueued while reading. Try to drain it
-       * or fill the buffer */
+       * or fill the buffer. Avoid doing that for dgrams */
       buf += rv;
       n -= rv;
       goto read_again;