bonding: clean the primary slave if there is no slave matching new primary

If the new primay is not matching any slave in the bond, the bond should
record it to params, clean the primary slave and select a new active slave.
Signed-off-by: Ding Tianhong <dingtianhong@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_options.c

@@ -1021,6 +1021,12 @@ int bond_option_primary_set(struct bonding *bond, struct bond_opt_value *newval)
 		}
 	}
 
+	if (bond->primary_slave) {
+		pr_info("%s: Setting primary slave to None.\n",
+			bond->dev->name);
+		bond->primary_slave = NULL;
+		bond_select_active_slave(bond);
+	}
 	strncpy(bond->params.primary, primary, IFNAMSIZ);
 	bond->params.primary[IFNAMSIZ - 1] = 0;