igc: Refactor igc_mac_entry_can_be_used()

The helper igc_mac_entry_can_be_used() implementation is a bit
convoluted since it does two different things: find a not-in-use slot
in mac_table or find an in-use slot where the address and address type
match. This patch does a code refactoring and break it up into two
helper functions.

With this patch we might traverse mac_table twice in some situations,
but this is not harmful performance-wise (mac_table has only 16 entries
and adding mac filters is not hot-path), and it improves igc_add_mac_
filter() readability considerably.
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_main.c

@@ -2176,25 +2176,44 @@ static void igc_nfc_filter_restore(struct igc_adapter *adapter)
 	spin_unlock(&adapter->nfc_lock);
 }
 
-/* If the filter to be added and an already existing filter express
- * the same address and address type, it should be possible to only
- * override the other configurations, for example the queue to steer
- * traffic.
- */
-static bool igc_mac_entry_can_be_used(const struct igc_mac_addr *entry,
-				      const u8 *addr, const u8 flags)
+static int igc_find_mac_filter(struct igc_adapter *adapter, const u8 *addr,
+			       u8 flags)
 {
-	if (!(entry->state & IGC_MAC_STATE_IN_USE))
-		return true;
+	int max_entries = adapter->hw.mac.rar_entry_count;
+	struct igc_mac_addr *entry;
+	int i;
 
-	if ((entry->state & IGC_MAC_STATE_SRC_ADDR) !=
-	    (flags & IGC_MAC_STATE_SRC_ADDR))
-		return false;
+	for (i = 0; i < max_entries; i++) {
+		entry = &adapter->mac_table[i];
 
-	if (!ether_addr_equal(addr, entry->addr))
-		return false;
+		if (!(entry->state & IGC_MAC_STATE_IN_USE))
+			continue;
+		if (!ether_addr_equal(addr, entry->addr))
+			continue;
+		if ((entry->state & IGC_MAC_STATE_SRC_ADDR) !=
+		    (flags & IGC_MAC_STATE_SRC_ADDR))
+			continue;
 
-	return true;
+		return i;
+	}
+
+	return -1;
+}
+
+static int igc_get_avail_mac_filter_slot(struct igc_adapter *adapter)
+{
+	int max_entries = adapter->hw.mac.rar_entry_count;
+	struct igc_mac_addr *entry;
+	int i;
+
+	for (i = 0; i < max_entries; i++) {
+		entry = &adapter->mac_table[i];
+
+		if (!(entry->state & IGC_MAC_STATE_IN_USE))
+			return i;
+	}
+
+	return -1;
 }
 
 /**
@@ -2212,33 +2231,28 @@ static bool igc_mac_entry_can_be_used(const struct igc_mac_addr *entry,
 int igc_add_mac_filter(struct igc_adapter *adapter, const u8 *addr,
 		       const s8 queue, const u8 flags)
 {
-	struct igc_hw *hw = &adapter->hw;
-	int rar_entries = hw->mac.rar_entry_count;
-	int i;
+	int index;
 
 	if (!is_valid_ether_addr(addr))
 		return -EINVAL;
 	if (flags & IGC_MAC_STATE_SRC_ADDR)
 		return -ENOTSUPP;
 
-	/* Search for the first empty entry in the MAC table.
-	 * Do not touch entries at the end of the table reserved for the VF MAC
-	 * addresses.
-	 */
-	for (i = 0; i < rar_entries; i++) {
-		if (!igc_mac_entry_can_be_used(&adapter->mac_table[i],
-					       addr, flags))
-			continue;
+	index = igc_find_mac_filter(adapter, addr, flags);
+	if (index >= 0)
+		goto update_queue_assignment;
 
-		ether_addr_copy(adapter->mac_table[i].addr, addr);
-		adapter->mac_table[i].queue = queue;
-		adapter->mac_table[i].state |= IGC_MAC_STATE_IN_USE | flags;
+	index = igc_get_avail_mac_filter_slot(adapter);
+	if (index < 0)
+		return -ENOSPC;
 
-		igc_set_mac_filter_hw(adapter, i, addr, queue);
-		return 0;
-	}
+	ether_addr_copy(adapter->mac_table[index].addr, addr);
+	adapter->mac_table[index].state |= IGC_MAC_STATE_IN_USE | flags;
+update_queue_assignment:
+	adapter->mac_table[index].queue = queue;
 
-	return -ENOSPC;
+	igc_set_mac_filter_hw(adapter, index, addr, queue);
+	return 0;
 }
 
 /**