net: usb: asix: add error handling for asix_mdio_* functions

This usb devices can be removed at any time, so we need to forward
correct error value if device was detached.
Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/asix_common.c

@@ -485,18 +485,23 @@ int asix_mdio_read(struct net_device *netdev, int phy_id, int loc)
 		return ret;
 	}
 
-	asix_read_cmd(dev, AX_CMD_READ_MII_REG, phy_id,
-				(__u16)loc, 2, &res, 0);
-	asix_set_hw_mii(dev, 0);
+	ret = asix_read_cmd(dev, AX_CMD_READ_MII_REG, phy_id, (__u16)loc, 2,
+			    &res, 0);
+	if (ret < 0)
+		goto out;
+
+	ret = asix_set_hw_mii(dev, 0);
+out:
 	mutex_unlock(&dev->phy_mutex);
 
 	netdev_dbg(dev->net, "asix_mdio_read() phy_id=0x%02x, loc=0x%02x, returns=0x%04x\n",
 			phy_id, loc, le16_to_cpu(res));
 
-	return le16_to_cpu(res);
+	return ret < 0 ? ret : le16_to_cpu(res);
 }
 
-void asix_mdio_write(struct net_device *netdev, int phy_id, int loc, int val)
+static int __asix_mdio_write(struct net_device *netdev, int phy_id, int loc,
+			     int val)
 {
 	struct usbnet *dev = netdev_priv(netdev);
 	__le16 res = cpu_to_le16(val);
@@ -516,15 +521,25 @@ void asix_mdio_write(struct net_device *netdev, int phy_id, int loc, int val)
 		ret = asix_read_cmd(dev, AX_CMD_STATMNGSTS_REG,
 				    0, 0, 1, &smsr, 0);
 	} while (!(smsr & AX_HOST_EN) && (i++ < 30) && (ret != -ENODEV));
-	if (ret == -ENODEV) {
-		mutex_unlock(&dev->phy_mutex);
-		return;
-	}
 
-	asix_write_cmd(dev, AX_CMD_WRITE_MII_REG, phy_id,
-		       (__u16)loc, 2, &res, 0);
-	asix_set_hw_mii(dev, 0);
+	if (ret == -ENODEV)
+		goto out;
+
+	ret = asix_write_cmd(dev, AX_CMD_WRITE_MII_REG, phy_id, (__u16)loc, 2,
+			     &res, 0);
+	if (ret < 0)
+		goto out;
+
+	ret = asix_set_hw_mii(dev, 0);
+out:
 	mutex_unlock(&dev->phy_mutex);
+
+	return ret < 0 ? ret : 0;
+}
+
+void asix_mdio_write(struct net_device *netdev, int phy_id, int loc, int val)
+{
+	__asix_mdio_write(netdev, phy_id, loc, val);
 }
 
 /* MDIO read and write wrappers for phylib */
@@ -539,8 +554,7 @@ int asix_mdio_bus_write(struct mii_bus *bus, int phy_id, int regnum, u16 val)
 {
 	struct usbnet *priv = bus->priv;
 
-	asix_mdio_write(priv->net, phy_id, regnum, val);
-	return 0;
+	return __asix_mdio_write(priv->net, phy_id, regnum, val);
 }
 
 int asix_mdio_read_nopm(struct net_device *netdev, int phy_id, int loc)