vmxnet3: prevent div-by-zero panic when ring resizing uninitialized dev

Linux is free to call ethtool ops as soon as a netdev exists when probe
finishes. However, we only allocate vmxnet3 tx/rx queues and initialize the
rx_buf_per_pkt field in struct vmxnet3_adapter when the interface is
opened (UP).
Signed-off-by: Bhavesh Davda <bhavesh@vmware.com>
Signed-off-by: Shreyas N Bhatewara <sbhatewara@vmware.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/vmxnet3/vmxnet3_drv.c

@@ -2958,6 +2958,7 @@ vmxnet3_probe_device(struct pci_dev *pdev,
 
 	adapter->num_rx_queues = num_rx_queues;
 	adapter->num_tx_queues = num_tx_queues;
+	adapter->rx_buf_per_pkt = 1;
 
 	size = sizeof(struct Vmxnet3_TxQueueDesc) * adapter->num_tx_queues;
 	size += sizeof(struct Vmxnet3_RxQueueDesc) * adapter->num_rx_queues;

drivers/net/vmxnet3/vmxnet3_ethtool.c

@@ -472,6 +472,12 @@ vmxnet3_set_ringparam(struct net_device *netdev,
 						VMXNET3_RX_RING_MAX_SIZE)
 		return -EINVAL;
 
+	/* if adapter not yet initialized, do nothing */
+	if (adapter->rx_buf_per_pkt == 0) {
+		netdev_err(netdev, "adapter not completely initialized, "
+			   "ring size cannot be changed yet\n");
+		return -EOPNOTSUPP;
+	}
 
 	/* round it up to a multiple of VMXNET3_RING_SIZE_ALIGN */
 	new_tx_ring_size = (param->tx_pending + VMXNET3_RING_SIZE_MASK) &

drivers/net/vmxnet3/vmxnet3_int.h

@@ -70,10 +70,10 @@
 /*
  * Version numbers
  */
-#define VMXNET3_DRIVER_VERSION_STRING   "1.1.29.0-k"
+#define VMXNET3_DRIVER_VERSION_STRING   "1.1.30.0-k"
 
 /* a 32-bit int, each byte encode a verion number in VMXNET3_DRIVER_VERSION */
-#define VMXNET3_DRIVER_VERSION_NUM      0x01011D00
+#define VMXNET3_DRIVER_VERSION_NUM      0x01011E00
 
 #if defined(CONFIG_PCI_MSI)
 	/* RSS only makes sense if MSI-X is supported. */