igc: Fix NFC rule validation

If we try to overwrite an existing rule with the same filter but
different action, we get EEXIST error as shown below.

$ ethtool -N eth0 flow-type ether dst <MACADDR> action 1 loc 10
$ ethtool -N eth0 flow-type ether dst <MACADDR> action 2 loc 10
rmgr: Cannot insert RX class rule: File exists

The second command is expected to overwrite the previous rule in location
10 and succeed.

This patch fixes igc_ethtool_check_nfc_rule() so it also checks the
rules location. In case they match, the rule under evaluation should not
be considered invalid.
Signed-off-by: Andre Guedes <andre.guedes@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igc/igc_ethtool.c

@@ -1225,8 +1225,8 @@ static void igc_ethtool_init_nfc_rule(struct igc_nfc_rule *rule,
  * Rules with both destination and source MAC addresses are considered invalid
  * since the driver doesn't support them.
  *
- * Also, if there is already another rule with the same filter, @rule is
- * considered invalid.
+ * Also, if there is already another rule with the same filter in a different
+ * location, @rule is considered invalid.
  *
  * Context: Expects adapter->nfc_rule_lock to be held by caller.
  *
@@ -1252,7 +1252,8 @@ static int igc_ethtool_check_nfc_rule(struct igc_adapter *adapter,
 
 	list_for_each_entry(tmp, &adapter->nfc_rule_list, list) {
 		if (!memcmp(&rule->filter, &tmp->filter,
-			    sizeof(rule->filter))) {
+			    sizeof(rule->filter)) &&
+		    tmp->location != rule->location) {
 			netdev_dbg(dev, "Rule already exists\n");
 			return -EEXIST;
 		}