net: hns3: add NULL pointer check for hns3_set/get_ringparam()

When pci devices init failed and haven't reinit, priv->ring is
NULL and hns3_set/get_ringparam() will access priv->ring. it
causes call trace.

So, add NULL pointer check for hns3_set/get_ringparam() to
avoid this situation.

Fixes: 5668abd ("net: hns3: add support for set_ringparam")
Signed-off-by: Hao Chen <chenhao288@hisilicon.com>
Signed-off-by: Guangbin Huang <huangguangbin2@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Author: Hao Chen

drivers/net/ethernet/hisilicon/hns3/hns3_ethtool.c

@@ -653,8 +653,8 @@ static void hns3_get_ringparam(struct net_device *netdev,
 	struct hnae3_handle *h = priv->ae_handle;
 	int rx_queue_index = h->kinfo.num_tqps;
 
-	if (hns3_nic_resetting(netdev)) {
-		netdev_err(netdev, "dev resetting!");
+	if (hns3_nic_resetting(netdev) || !priv->ring) {
+		netdev_err(netdev, "failed to get ringparam value, due to dev resetting or uninited\n");
 		return;
 	}
 
@@ -1074,8 +1074,14 @@ static int hns3_check_ringparam(struct net_device *ndev,
 {
 #define RX_BUF_LEN_2K 2048
 #define RX_BUF_LEN_4K 4096
-	if (hns3_nic_resetting(ndev))
+
+	struct hns3_nic_priv *priv = netdev_priv(ndev);
+
+	if (hns3_nic_resetting(ndev) || !priv->ring) {
+		netdev_err(ndev, "failed to set ringparam value, due to dev resetting or uninited\n");
 		return -EBUSY;
+	}
+
 
 	if (param->rx_mini_pending || param->rx_jumbo_pending)
 		return -EINVAL;