ice: Respond to a NETDEV_UNREGISTER event for LAG

When the PF is a member of a link aggregate, and the driver
is removed, the process will hang unless we respond to the
NETDEV_UNREGISTER event that is sent to the event_handler
for LAG.

Add a case statement for the ice_lag_event_handler to unlink
the PF from the link aggregate.

Also remove code that was incorrectly applying a dev_hold to
peer_netdevs that were associated with the ice driver.

Fixes: df006dd4 ("ice: Add initial support framework for LAG")
Signed-off-by: Dave Ertman <david.m.ertman@intel.com>
Tested-by: Tony Brelinski <tony.brelinski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice_lag.c

@@ -100,9 +100,9 @@ static void ice_display_lag_info(struct ice_lag *lag)
  */
 static void ice_lag_info_event(struct ice_lag *lag, void *ptr)
 {
-	struct net_device *event_netdev, *netdev_tmp;
 	struct netdev_notifier_bonding_info *info;
 	struct netdev_bonding_info *bonding_info;
+	struct net_device *event_netdev;
 	const char *lag_netdev_name;
 
 	event_netdev = netdev_notifier_info_to_dev(ptr);
@@ -123,19 +123,6 @@ static void ice_lag_info_event(struct ice_lag *lag, void *ptr)
 		goto lag_out;
 	}
 
-	rcu_read_lock();
-	for_each_netdev_in_bond_rcu(lag->upper_netdev, netdev_tmp) {
-		if (!netif_is_ice(netdev_tmp))
-			continue;
-
-		if (netdev_tmp && netdev_tmp != lag->netdev &&
-		    lag->peer_netdev != netdev_tmp) {
-			dev_hold(netdev_tmp);
-			lag->peer_netdev = netdev_tmp;
-		}
-	}
-	rcu_read_unlock();
-
 	if (bonding_info->slave.state)
 		ice_lag_set_backup(lag);
 	else
@@ -319,6 +306,9 @@ ice_lag_event_handler(struct notifier_block *notif_blk, unsigned long event,
 	case NETDEV_BONDING_INFO:
 		ice_lag_info_event(lag, ptr);
 		break;
+	case NETDEV_UNREGISTER:
+		ice_lag_unlink(lag, ptr);
+		break;
 	default:
 		break;
 	}