net/tap: do not overwrite flow API errors

[ upstream commit 11b90b53c6716ca9bc713bab6cfba039fe8e38cb ]

All flow errors were ending up being reported as not supported,
even when the error path was previously setting a valid and
better error message.

Example, asking for a non-existent queue in flow.

Before:
testpmd> flow create 0 ingress pattern eth src is 06:05:04:03:02:01 \
  / end actions queue index 12 / end
port_flow_complain(): Caught PMD error type 16 (specific action):
cause: 0x7fffc46c1e18, action not supported: Operation not supported

After:
testpmd> flow create 0 ingress pattern eth src is 06:05:04:03:02:01 \
  / end actions queue index 12 / end
port_flow_complain(): Caught PMD error type 16 (specific action):
cause: 0x7fffa54e1d88, queue index out of range: Numerical result
       out of range

Fixes: f46900d ("net/tap: fix flow and port commands")
Fixes: de96fe6 ("net/tap: add basic flow API patterns and actions")

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>

drivers/net/tap/tap_flow.c

@@ -1082,8 +1082,11 @@ priv_flow_process(struct pmd_internals *pmd,
 		}
 		/* use flower filter type */
 		tap_nlattr_add(&flow->msg.nh, TCA_KIND, sizeof("flower"), "flower");
-		if (tap_nlattr_nested_start(&flow->msg, TCA_OPTIONS) < 0)
-			goto exit_item_not_supported;
+		if (tap_nlattr_nested_start(&flow->msg, TCA_OPTIONS) < 0) {
+			rte_flow_error_set(error, ENOMEM, RTE_FLOW_ERROR_TYPE_ACTION,
+					   actions, "could not allocated netlink msg");
+			goto exit_return_error;
+		}
 	}
 	for (; items->type != RTE_FLOW_ITEM_TYPE_END; ++items) {
 		const struct tap_flow_items *token = NULL;
@@ -1199,9 +1202,12 @@ priv_flow_process(struct pmd_internals *pmd,
 			if (action)
 				goto exit_action_not_supported;
 			action = 1;
-			if (!queue ||
-			    (queue->index > pmd->dev->data->nb_rx_queues - 1))
-				goto exit_action_not_supported;
+			if (queue->index >= pmd->dev->data->nb_rx_queues) {
+				rte_flow_error_set(error, ERANGE,
+						   RTE_FLOW_ERROR_TYPE_ACTION, actions,
+						   "queue index out of range");
+				goto exit_return_error;
+			}
 			if (flow) {
 				struct action_data adata = {
 					.id = "skbedit",
@@ -1227,15 +1233,15 @@ priv_flow_process(struct pmd_internals *pmd,
 			if (!pmd->rss_enabled) {
 				err = rss_enable(pmd, attr, error);
 				if (err)
-					goto exit_action_not_supported;
+					goto exit_return_error;
 			}
 			if (flow)
 				err = rss_add_actions(flow, pmd, rss, error);
 		} else {
 			goto exit_action_not_supported;
 		}
 		if (err)
-			goto exit_action_not_supported;
+			goto exit_return_error;
 	}
 	/* When fate is unknown, drop traffic. */
 	if (!action) {
@@ -1258,6 +1264,7 @@ priv_flow_process(struct pmd_internals *pmd,
 exit_action_not_supported:
 	rte_flow_error_set(error, ENOTSUP, RTE_FLOW_ERROR_TYPE_ACTION,
 			   actions, "action not supported");
+exit_return_error:
 	return -rte_errno;
 }