openvswitch: Additional logging for -EINVAL on flow setups.

There are many possible ways that a flow can be invalid so we've
added logging for most of them. This adds logs for the remaining
possible cases so there isn't any ambiguity while debugging.

CC: Federico Iezzi <fiezzi@enter.it>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Thomas Graf <tgraf@noironetworks.com>
Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index a532a9c..04a26ae 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -817,10 +817,14 @@
 
 	/* Must have key and actions. */
 	error = -EINVAL;
-	if (!a[OVS_FLOW_ATTR_KEY])
+	if (!a[OVS_FLOW_ATTR_KEY]) {
+		OVS_NLERR("Flow key attribute not present in new flow.\n");
 		goto error;
-	if (!a[OVS_FLOW_ATTR_ACTIONS])
+	}
+	if (!a[OVS_FLOW_ATTR_ACTIONS]) {
+		OVS_NLERR("Flow actions attribute not present in new flow.\n");
 		goto error;
+	}
 
 	/* Most of the time we need to allocate a new flow, do it before
 	 * locking.
@@ -979,8 +983,10 @@
 
 	/* Extract key. */
 	error = -EINVAL;
-	if (!a[OVS_FLOW_ATTR_KEY])
+	if (!a[OVS_FLOW_ATTR_KEY]) {
+		OVS_NLERR("Flow key attribute not present in set flow.\n");
 		goto error;
+	}
 
 	ovs_match_init(&match, &key, &mask);
 	error = ovs_nla_get_match(&match,