net: fix ethtool->set_flags not intended -EINVAL return value

After commit d5dbda23804156ae6f35025ade5307a49d1db6d7 "ethtool: Add
support for vlan accleration.", drivers that have NETIF_F_HW_VLAN_TX,
and/or NETIF_F_HW_VLAN_RX feature, but do not allow enable/disable vlan
acceleration via ethtool set_flags, always return -EINVAL from that
function. Fix by returning -EINVAL only if requested features do not
match current settings and can not be changed by driver.

Change any driver that define ethtool->set_flags to use
ethtool_invalid_flags() to avoid similar problems in the future
(also on drivers that do not have the problem).

Tested with modified (to reproduce this bug) myri10ge driver.

Cc: stable@kernel.org # 2.6.37+
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/netxen/netxen_nic_ethtool.c

@@ -871,7 +871,7 @@ static int netxen_nic_set_flags(struct net_device *netdev, u32 data)
 	struct netxen_adapter *adapter = netdev_priv(netdev);
 	int hw_lro;
 
-	if (data & ~ETH_FLAG_LRO)
+	if (ethtool_invalid_flags(netdev, data, ETH_FLAG_LRO))
 		return -EINVAL;
 
 	if (!(adapter->capabilities & NX_FW_CAPABILITY_HW_LRO))

drivers/net/qlcnic/qlcnic_ethtool.c

@@ -1003,7 +1003,7 @@ static int qlcnic_set_flags(struct net_device *netdev, u32 data)
 	struct qlcnic_adapter *adapter = netdev_priv(netdev);
 	int hw_lro;
 
-	if (data & ~ETH_FLAG_LRO)
+	if (ethtool_invalid_flags(netdev, data, ETH_FLAG_LRO))
 		return -EINVAL;
 
 	if (!(adapter->capabilities & QLCNIC_FW_CAPABILITY_HW_LRO))

drivers/net/s2io.c

@@ -6726,7 +6726,7 @@ static int s2io_ethtool_set_flags(struct net_device *dev, u32 data)
 	int rc = 0;
 	int changed = 0;
 
-	if (data & ~ETH_FLAG_LRO)
+	if (ethtool_invalid_flags(dev, data, ETH_FLAG_LRO))
 		return -EINVAL;
 
 	if (data & ETH_FLAG_LRO) {

drivers/net/vmxnet3/vmxnet3_ethtool.c

@@ -304,8 +304,8 @@ vmxnet3_set_flags(struct net_device *netdev, u32 data)
 	u8 lro_present = (netdev->features & NETIF_F_LRO) == 0 ? 0 : 1;
 	unsigned long flags;
 
-	if (data & ~ETH_FLAG_LRO)
-		return -EOPNOTSUPP;
+	if (ethtool_invalid_flags(netdev, data, ETH_FLAG_LRO))
+		return -EINVAL;
 
 	if (lro_requested ^ lro_present) {
 		/* toggle the LRO feature*/

drivers/net/vxge/vxge-ethtool.c

@@ -1117,8 +1117,8 @@ static int vxge_set_flags(struct net_device *dev, u32 data)
 	struct vxgedev *vdev = netdev_priv(dev);
 	enum vxge_hw_status status;
 
-	if (data & ~ETH_FLAG_RXHASH)
-		return -EOPNOTSUPP;
+	if (ethtool_invalid_flags(dev, data, ETH_FLAG_RXHASH))
+		return -EINVAL;
 
 	if (!!(data & ETH_FLAG_RXHASH) == vdev->devh->config.rth_en)
 		return 0;

include/linux/ethtool.h

@@ -680,6 +680,7 @@ int ethtool_op_set_ufo(struct net_device *dev, u32 data);
 u32 ethtool_op_get_flags(struct net_device *dev);
 int ethtool_op_set_flags(struct net_device *dev, u32 data, u32 supported);
 void ethtool_ntuple_flush(struct net_device *dev);
+bool ethtool_invalid_flags(struct net_device *dev, u32 data, u32 supported);
 
 /**
  * &ethtool_ops - Alter and report network device settings

net/core/ethtool.c

@@ -141,9 +141,24 @@ u32 ethtool_op_get_flags(struct net_device *dev)
 }
 EXPORT_SYMBOL(ethtool_op_get_flags);
 
+/* Check if device can enable (or disable) particular feature coded in "data"
+ * argument. Flags "supported" describe features that can be toggled by device.
+ * If feature can not be toggled, it state (enabled or disabled) must match
+ * hardcoded device features state, otherwise flags are marked as invalid.
+ */
+bool ethtool_invalid_flags(struct net_device *dev, u32 data, u32 supported)
+{
+	u32 features = dev->features & flags_dup_features;
+	/* "data" can contain only flags_dup_features bits,
+	 * see __ethtool_set_flags */
+
+	return (features & ~supported) != (data & ~supported);
+}
+EXPORT_SYMBOL(ethtool_invalid_flags);
+
 int ethtool_op_set_flags(struct net_device *dev, u32 data, u32 supported)
 {
-	if (data & ~supported)
+	if (ethtool_invalid_flags(dev, data, supported))
 		return -EINVAL;
 
 	dev->features = ((dev->features & ~flags_dup_features) |