[dpdk-dev] [PATCH 1/2] net/mlx4: fix Rx after updating number of queues

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

When not in isolated mode, internal flow rules are automatically maintained
by the PMD to receive traffic according to global device settings (MAC,
VLAN, promiscuous mode and so on).

Since RSS support was added to the mix, it must also check whether Rx queue
configuration has changed when refreshing flow rules to prevent the
following from happening:

- With a smaller number of Rx queues, traffic is implicitly dropped since
  the existing RSS context cannot be re-applied.
- With a larger number of Rx queues, traffic remains balanced within the
  original (smaller) set of queues.

One workaround before this commit was to temporarily enter/leave isolated
mode to make it regenerate internal flow rules.

Fixes: 7d8675956f57 ("net/mlx4: add RSS support outside flow API")

Signed-off-by: Adrien Mazarguil <adrien.mazarguil@6wind.com>
---
 drivers/net/mlx4/mlx4_flow.c | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/drivers/net/mlx4/mlx4_flow.c b/drivers/net/mlx4/mlx4_flow.c
index 7a6097f..86bac1b 100644
--- a/drivers/net/mlx4/mlx4_flow.c
+++ b/drivers/net/mlx4/mlx4_flow.c
@@ -1342,6 +1342,7 @@ mlx4_flow_internal(struct priv *priv, struct rte_flow_error *error)
 			assert(flow->ibv_attr->type == IBV_FLOW_ATTR_NORMAL);
 			assert(flow->ibv_attr->num_of_specs == 1);
 			assert(eth->type == IBV_FLOW_SPEC_ETH);
+			assert(flow->rss);
 			if (rule_vlan &&
 			    (eth->val.vlan_tag != *rule_vlan ||
 			     eth->mask.vlan_tag != RTE_BE16(0x0fff)))
@@ -1354,8 +1355,13 @@ mlx4_flow_internal(struct priv *priv, struct rte_flow_error *error)
 				    eth->val.src_mac[j] != UINT8_C(0x00) ||
 				    eth->mask.src_mac[j] != UINT8_C(0x00))
 					break;
-			if (j == sizeof(mac->addr_bytes))
-				break;
+			if (j != sizeof(mac->addr_bytes))
+				continue;
+			if (flow->rss->queues != queues ||
+			    memcmp(flow->rss->queue_id, rss_conf->queue,
+				   queues * sizeof(flow->rss->queue_id[0])))
+				continue;
+			break;
 		}
 		if (!flow || !flow->internal) {
 			/* Not found, create a new flow rule. */
@@ -1389,6 +1395,13 @@ mlx4_flow_internal(struct priv *priv, struct rte_flow_error *error)
 					break;
 			}
 		}
+		if (flow && flow->internal) {
+			assert(flow->rss);
+			if (flow->rss->queues != queues ||
+			    memcmp(flow->rss->queue_id, rss_conf->queue,
+				   queues * sizeof(flow->rss->queue_id[0])))
+				flow = NULL;
+		}
 		if (!flow || !flow->internal) {
 			/* Not found, create a new flow rule. */
 			if (priv->dev->data->promiscuous) {
-- 
2.1.4