[PATCHv2,net-next,2/8] ethtool: Allow drivers to select RX NFC rule locations

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index b38bf69..d901714 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -489,7 +489,10 @@  struct ethtool_rx_flow_spec {
  * on return.
  *
  * For %ETHTOOL_GRXCLSRLCNT, @rule_cnt is set to the number of defined
- * rules on return.
+ * rules on return.  If @data is non-zero on return then it is the
+ * size of the rule table, plus the flag %RX_CLS_LOC_SPECIAL if the
+ * driver supports any special location values.  If that flag is not
+ * set in @data then special location values should not be used.
  *
  * For %ETHTOOL_GRXCLSRULE, @fs.@location specifies the location of an
  * existing rule on entry and @fs contains the rule on return.
@@ -501,10 +504,23 @@  struct ethtool_rx_flow_spec {
  * must use the second parameter to get_rxnfc() instead of @rule_locs.
  *
  * For %ETHTOOL_SRXCLSRLINS, @fs specifies the rule to add or update.
- * @fs.@location specifies the location to use and must not be ignored.
+ * @fs.@location either specifies the location to use or is a special
+ * location value with %RX_CLS_LOC_SPECIAL flag set.  On return,
+ * @fs.@location is the actual rule location.
  *
  * For %ETHTOOL_SRXCLSRLDEL, @fs.@location specifies the location of an
  * existing rule on entry.
+ *
+ * A driver supporting the special location values for
+ * %ETHTOOL_SRXCLSRLINS may add the rule at any suitable unused
+ * location, and may remove a rule at a later location (lower
+ * priority) that matches exactly the same set of flows.  The special
+ * values are: %RX_CLS_LOC_ANY, selecting any location;
+ * %RX_CLS_LOC_FIRST, selecting the first suitable location (maximum
+ * priority); and %RX_CLS_LOC_LAST, selecting the last suitable
+ * location (minimum priority).  Additional special values may be
+ * defined in future and drivers must return -%EINVAL for any
+ * unrecognised value.
  */
 struct ethtool_rxnfc {
 	__u32				cmd;
@@ -1141,6 +1157,12 @@  struct ethtool_ops {
 
 #define	RX_CLS_FLOW_DISC	0xffffffffffffffffULL
 
+/* Special RX classification rule insert location values */
+#define RX_CLS_LOC_SPECIAL	0x80000000	/* flag */
+#define RX_CLS_LOC_ANY		0xffffffff
+#define RX_CLS_LOC_FIRST	0xfffffffe
+#define RX_CLS_LOC_LAST		0xfffffffd
+
 /* Reset flags */
 /* The reset() operation must clear the flags for the components which
  * were actually reset.  On successful return, the flags indicate the
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 597732c..e88b80d 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -439,6 +439,7 @@  static noinline_for_stack int ethtool_set_rxnfc(struct net_device *dev,
 {
 	struct ethtool_rxnfc info;
 	size_t info_size = sizeof(info);
+	int rc;
 
 	if (!dev->ethtool_ops->set_rxnfc)
 		return -EOPNOTSUPP;
@@ -454,7 +455,15 @@  static noinline_for_stack int ethtool_set_rxnfc(struct net_device *dev,
 	if (copy_from_user(&info, useraddr, info_size))
 		return -EFAULT;
 
-	return dev->ethtool_ops->set_rxnfc(dev, &info);
+	rc = dev->ethtool_ops->set_rxnfc(dev, &info);
+	if (rc)
+		return rc;
+
+	if (cmd == ETHTOOL_SRXCLSRLINS &&
+	    copy_to_user(useraddr, &info, info_size))
+		return -EFAULT;
+
+	return 0;
 }
 
 static noinline_for_stack int ethtool_get_rxnfc(struct net_device *dev,
diff --git a/net/socket.c b/net/socket.c
index e62b4f0..2cad581 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2758,10 +2758,10 @@  static int ethtool_ioctl(struct net *net, struct compat_ifreq __user *ifr32)
 	case ETHTOOL_GRXRINGS:
 	case ETHTOOL_GRXCLSRLCNT:
 	case ETHTOOL_GRXCLSRULE:
+	case ETHTOOL_SRXCLSRLINS:
 		convert_out = true;
 		/* fall through */
 	case ETHTOOL_SRXCLSRLDEL:
-	case ETHTOOL_SRXCLSRLINS:
 		buf_size += sizeof(struct ethtool_rxnfc);
 		convert_in = true;
 		break;