iavf: fix err handling for MAC replace

Defer removal of current primary MAC until a replacement is successfully
added. Previous implementation would left filter list with no primary MAC.
This was found while reading the code.

The patch takes advantage of the fact that there can only be a single primary
MAC filter at any time ([1] by Piotr)

Piotr has also applied some review suggestions during our internal patch
submittal process.

[1] https://lore.kernel.org/netdev/20230614145302.902301-2-piotrx.gardocki@intel.com/

Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
Signed-off-by: Piotr Gardocki <piotrx.gardocki@intel.com>
Signed-off-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/iavf/iavf_main.c

@@ -1007,40 +1007,36 @@ int iavf_replace_primary_mac(struct iavf_adapter *adapter,
 			     const u8 *new_mac)
 {
 	struct iavf_hw *hw = &adapter->hw;
-	struct iavf_mac_filter *f;
+	struct iavf_mac_filter *new_f;
+	struct iavf_mac_filter *old_f;
 
 	spin_lock_bh(&adapter->mac_vlan_list_lock);
 
-	list_for_each_entry(f, &adapter->mac_filter_list, list) {
-		f->is_primary = false;
+	new_f = iavf_add_filter(adapter, new_mac);
+	if (!new_f) {
+		spin_unlock_bh(&adapter->mac_vlan_list_lock);
+		return -ENOMEM;
 	}
 
-	f = iavf_find_filter(adapter, hw->mac.addr);
-	if (f) {
-		f->remove = true;
+	old_f = iavf_find_filter(adapter, hw->mac.addr);
+	if (old_f) {
+		old_f->is_primary = false;
+		old_f->remove = true;
 		adapter->aq_required |= IAVF_FLAG_AQ_DEL_MAC_FILTER;
 	}
-
-	f = iavf_add_filter(adapter, new_mac);
-
-	if (f) {
-		/* Always send the request to add if changing primary MAC
-		 * even if filter is already present on the list
-		 */
-		f->is_primary = true;
-		f->add = true;
-		adapter->aq_required |= IAVF_FLAG_AQ_ADD_MAC_FILTER;
-		ether_addr_copy(hw->mac.addr, new_mac);
-	}
+	/* Always send the request to add if changing primary MAC,
+	 * even if filter is already present on the list
+	 */
+	new_f->is_primary = true;
+	new_f->add = true;
+	adapter->aq_required |= IAVF_FLAG_AQ_ADD_MAC_FILTER;
+	ether_addr_copy(hw->mac.addr, new_mac);
 
 	spin_unlock_bh(&adapter->mac_vlan_list_lock);
 
 	/* schedule the watchdog task to immediately process the request */
-	if (f) {
-		mod_delayed_work(adapter->wq, &adapter->watchdog_task, 0);
-		return 0;
-	}
-	return -ENOMEM;
+	mod_delayed_work(adapter->wq, &adapter->watchdog_task, 0);
+	return 0;
 }
 
 /**