net: bonding: Add extack messages for some enslave failures

A number of bond_enslave errors are logged using the netdev_err API.
Return those messages to userspace via the extack facility.

Signed-off-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_main.c

@@ -1348,12 +1348,14 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
 
 	/* already in-use? */
 	if (netdev_is_rx_handler_busy(slave_dev)) {
+		NL_SET_ERR_MSG(extack, "Device is in use and cannot be enslaved");
 		netdev_err(bond_dev,
 			   "Error: Device is in use and cannot be enslaved\n");
 		return -EBUSY;
 	}
 
 	if (bond_dev == slave_dev) {
+		NL_SET_ERR_MSG(extack, "Cannot enslave bond to itself.");
 		netdev_err(bond_dev, "cannot enslave bond to itself.\n");
 		return -EPERM;
 	}
@@ -1364,6 +1366,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
 		netdev_dbg(bond_dev, "%s is NETIF_F_VLAN_CHALLENGED\n",
 			   slave_dev->name);
 		if (vlan_uses_dev(bond_dev)) {
+			NL_SET_ERR_MSG(extack, "Can not enslave VLAN challenged device to VLAN enabled bond");
 			netdev_err(bond_dev, "Error: cannot enslave VLAN challenged slave %s on VLAN enabled bond %s\n",
 				   slave_dev->name, bond_dev->name);
 			return -EPERM;
@@ -1383,6 +1386,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
 	 * enslaving it; the old ifenslave will not.
 	 */
 	if (slave_dev->flags & IFF_UP) {
+		NL_SET_ERR_MSG(extack, "Device can not be enslaved while up");
 		netdev_err(bond_dev, "%s is up - this may be due to an out of date ifenslave\n",
 			   slave_dev->name);
 		return -EPERM;
@@ -1423,6 +1427,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
 						 bond_dev);
 		}
 	} else if (bond_dev->type != slave_dev->type) {
+		NL_SET_ERR_MSG(extack, "Device type is different from other slaves");
 		netdev_err(bond_dev, "%s ether type (%d) is different from other slaves (%d), can not enslave it\n",
 			   slave_dev->name, slave_dev->type, bond_dev->type);
 		return -EINVAL;
@@ -1430,6 +1435,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
 
 	if (slave_dev->type == ARPHRD_INFINIBAND &&
 	    BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
+		NL_SET_ERR_MSG(extack, "Only active-backup mode is supported for infiniband slaves");
 		netdev_warn(bond_dev, "Type (%d) supports only active-backup mode\n",
 			    slave_dev->type);
 		res = -EOPNOTSUPP;
@@ -1445,6 +1451,7 @@ int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
 				bond->params.fail_over_mac = BOND_FOM_ACTIVE;
 				netdev_warn(bond_dev, "Setting fail_over_mac to active for active-backup mode\n");
 			} else {
+				NL_SET_ERR_MSG(extack, "Slave device does not support setting the MAC address, but fail_over_mac is not set to active");
 				netdev_err(bond_dev, "The slave device specified does not support setting the MAC address, but fail_over_mac is not set to active\n");
 				res = -EOPNOTSUPP;
 				goto err_undo_flags;