[PATCH net 2/5] ibmvnic: Fix MTU settings

[Thomas Falcon]

In the current driver, the MTU is set to the maximum value
capable for the backing device. This patch sets the MTU to the
default value for a Linux net device. It also corrects a
discrepancy between MTU values received from firmware, which includes
the ethernet header length, and net device MTU values. Finally, it removes
redundant min/max MTU assignments after device initialization.

Signed-off-by: Thomas Falcon <tlfalcon at linux.vnet.ibm.com>
---
 drivers/net/ethernet/ibm/ibmvnic.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/ibmvnic.c
index 48debde2..f95f6a4 100644
--- a/drivers/net/ethernet/ibm/ibmvnic.c
+++ b/drivers/net/ethernet/ibm/ibmvnic.c
@@ -1496,7 +1496,7 @@ static void init_sub_crqs(struct ibmvnic_adapter *adapter, int retry)
 		adapter->req_rx_queues = adapter->opt_rx_comp_queues;
 		adapter->req_rx_add_queues = adapter->max_rx_add_queues;
 
-		adapter->req_mtu = adapter->max_mtu;
+		adapter->req_mtu = adapter->netdev->mtu + ETH_HLEN;
 	}
 
 	total_queues = adapter->req_tx_queues + adapter->req_rx_queues;
@@ -2626,12 +2626,12 @@ static void handle_query_cap_rsp(union ibmvnic_crq *crq,
 		break;
 	case MIN_MTU:
 		adapter->min_mtu = be64_to_cpu(crq->query_capability.number);
-		netdev->min_mtu = adapter->min_mtu;
+		netdev->min_mtu = adapter->min_mtu - ETH_HLEN;
 		netdev_dbg(netdev, "min_mtu = %lld\n", adapter->min_mtu);
 		break;
 	case MAX_MTU:
 		adapter->max_mtu = be64_to_cpu(crq->query_capability.number);
-		netdev->max_mtu = adapter->max_mtu;
+		netdev->max_mtu = adapter->max_mtu - ETH_HLEN;
 		netdev_dbg(netdev, "max_mtu = %lld\n", adapter->max_mtu);
 		break;
 	case MAX_MULTICAST_FILTERS:
@@ -3672,9 +3672,7 @@ static void handle_crq_init_rsp(struct work_struct *work)
 		goto task_failed;
 
 	netdev->real_num_tx_queues = adapter->req_tx_queues;
-	netdev->mtu = adapter->req_mtu;
-	netdev->min_mtu = adapter->min_mtu;
-	netdev->max_mtu = adapter->max_mtu;
+	netdev->mtu = adapter->req_mtu - ETH_HLEN;
 
 	if (adapter->failover) {
 		adapter->failover = false;
@@ -3814,7 +3812,7 @@ static int ibmvnic_probe(struct vio_dev *dev, const struct vio_device_id *id)
 	}
 
 	netdev->real_num_tx_queues = adapter->req_tx_queues;
-	netdev->mtu = adapter->req_mtu;
+	netdev->mtu = adapter->req_mtu - ETH_HLEN;
 
 	rc = register_netdev(netdev);
 	if (rc) {
-- 
1.8.3.1