net: Implement SFEATURES compatibility for not updated drivers

Use discrete setting ops for not updated drivers. This will not make
them conform to full G/SFEATURES semantics, though.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 54d776c..aac3e2e 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -591,6 +591,9 @@
  *      Probably there are other device-specific constraints on some features
  *      in the set. When %ETHTOOL_F_UNSUPPORTED is set, .valid is considered
  *      here as though ignored bits were cleared.
+ *   %ETHTOOL_F_COMPAT - some or all changes requested were made by calling
+ *      compatibility functions. Requested offload state cannot be properly
+ *      managed by kernel.
  *
  * Meaning of bits in the masks are obtained by %ETHTOOL_GSSET_INFO (number of
  * bits in the arrays - always multiple of 32) and %ETHTOOL_GSTRINGS commands
@@ -600,10 +603,12 @@
 enum ethtool_sfeatures_retval_bits {
 	ETHTOOL_F_UNSUPPORTED__BIT,
 	ETHTOOL_F_WISH__BIT,
+	ETHTOOL_F_COMPAT__BIT,
 };
 
 #define ETHTOOL_F_UNSUPPORTED   (1 << ETHTOOL_F_UNSUPPORTED__BIT)
 #define ETHTOOL_F_WISH          (1 << ETHTOOL_F_WISH__BIT)
+#define ETHTOOL_F_COMPAT        (1 << ETHTOOL_F_COMPAT__BIT)
 
 #ifdef __KERNEL__