net/cxgbe: fix jumbo frame flag condition

[ upstream commit 5dfbad5 ]

The jumbo frame uses the 'RTE_ETHER_MAX_LEN' as boundary condition.
If the Ether overhead is larger than 18 when it supports VLAN tag,
that will cause the jumbo flag rx offload is wrong when MTU size is
'RTE_ETHER_MTU'.

This fix will normalize the boundary condition with 'RTE_ETHER_MTU'
and overhead even though current overhead is 18.

Fixes: 4b2eff4 ("cxgbe: enable jumbo frames")
Fixes: 0ec33be ("cxgbe: allow to change mtu")

Signed-off-by: Steve Yang <stevex.yang@intel.com>
Reviewed-by: Ferruh Yigit <ferruh.yigit@intel.com>

drivers/net/cxgbe/cxgbe.h

@@ -19,6 +19,10 @@
 #define CXGBE_MAX_RX_PKTLEN (9000 + RTE_ETHER_HDR_LEN + \
 				RTE_ETHER_CRC_LEN) /* max pkt */
 
+/* The max frame size with default MTU */
+#define CXGBE_ETH_MAX_LEN (RTE_ETHER_MTU + \
+		RTE_ETHER_HDR_LEN + RTE_ETHER_CRC_LEN)
+
 /* Max poll time is 100 * 100msec = 10 sec */
 #define CXGBE_LINK_STATUS_POLL_MS 100 /* 100ms */
 #define CXGBE_LINK_STATUS_POLL_CNT 100 /* Max number of times to poll */

drivers/net/cxgbe/cxgbe_ethdev.c

@@ -300,7 +300,7 @@ int cxgbe_dev_mtu_set(struct rte_eth_dev *eth_dev, uint16_t mtu)
 		return -EINVAL;
 
 	/* set to jumbo mode if needed */
-	if (new_mtu > RTE_ETHER_MAX_LEN)
+	if (new_mtu > CXGBE_ETH_MAX_LEN)
 		eth_dev->data->dev_conf.rxmode.offloads |=
 			DEV_RX_OFFLOAD_JUMBO_FRAME;
 	else
@@ -669,7 +669,7 @@ int cxgbe_dev_rx_queue_setup(struct rte_eth_dev *eth_dev,
 		rxq->fl.size = temp_nb_desc;
 
 	/* Set to jumbo mode if necessary */
-	if (pkt_len > RTE_ETHER_MAX_LEN)
+	if (pkt_len > CXGBE_ETH_MAX_LEN)
 		eth_dev->data->dev_conf.rxmode.offloads |=
 			DEV_RX_OFFLOAD_JUMBO_FRAME;
 	else