igb: Fix removal of unicast MAC filters of VFs

Move checking condition of VF MAC filter before clearing
or adding MAC filter to VF to prevent potential blackout caused
by removal of necessary and working VF's MAC filter.

Fixes: 1b8b062a ("igb: add VF trust infrastructure")
Signed-off-by: Karen Sornek <karen.sornek@intel.com>
Tested-by: Konrad Jankowski <konrad0.jankowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/igb/igb_main.c

@@ -7648,19 +7648,6 @@ static int igb_set_vf_mac_filter(struct igb_adapter *adapter, const int vf,
 	struct vf_mac_filter *entry = NULL;
 	int ret = 0;
 
-	switch (info) {
-	case E1000_VF_MAC_FILTER_CLR:
-		/* remove all unicast MAC filters related to the current VF */
-		list_for_each(pos, &adapter->vf_macs.l) {
-			entry = list_entry(pos, struct vf_mac_filter, l);
-			if (entry->vf == vf) {
-				entry->vf = -1;
-				entry->free = true;
-				igb_del_mac_filter(adapter, entry->vf_mac, vf);
-			}
-		}
-		break;
-	case E1000_VF_MAC_FILTER_ADD:
 	if ((vf_data->flags & IGB_VF_FLAG_PF_SET_MAC) &&
 	    !vf_data->trusted) {
 		dev_warn(&pdev->dev,
@@ -7675,6 +7662,19 @@ static int igb_set_vf_mac_filter(struct igb_adapter *adapter, const int vf,
 		return -EINVAL;
 	}
 
+	switch (info) {
+	case E1000_VF_MAC_FILTER_CLR:
+		/* remove all unicast MAC filters related to the current VF */
+		list_for_each(pos, &adapter->vf_macs.l) {
+			entry = list_entry(pos, struct vf_mac_filter, l);
+			if (entry->vf == vf) {
+				entry->vf = -1;
+				entry->free = true;
+				igb_del_mac_filter(adapter, entry->vf_mac, vf);
+			}
+		}
+		break;
+	case E1000_VF_MAC_FILTER_ADD:
 		/* try to find empty slot in the list */
 		list_for_each(pos, &adapter->vf_macs.l) {
 			entry = list_entry(pos, struct vf_mac_filter, l);