1 files changed, 17 insertions, 2 deletions

diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index a1086fb0c0c7..74ead9eca126 100644
--- a/net/core/ethtool.c
+++ b/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) |
@@ -513,7 +528,7 @@ static int ethtool_set_one_feature(struct net_device *dev,
         }
 }
 
-static int __ethtool_set_flags(struct net_device *dev, u32 data)
+int __ethtool_set_flags(struct net_device *dev, u32 data)
 {
         u32 changed;