bonding:record primary when modify it via sysfs

If we modify primary via sysfs and it is not a valid slave,
we should record it for future use, and this behavior is the same with
bond_check_params().

Signed-off-by: Weiping Pan <wpan@redhat.com>
Acked-by: Nicolas de Pesloüan <nicolas.2p.debian@free.fr>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bonding/bond_sysfs.c

@@ -1082,8 +1082,12 @@ static ssize_t bonding_store_primary(struct device *d,
 		}
 	}
 
-	pr_info("%s: Unable to set %.*s as primary slave.\n",
-		bond->dev->name, (int)strlen(buf) - 1, buf);
+	strncpy(bond->params.primary, ifname, IFNAMSIZ);
+	bond->params.primary[IFNAMSIZ - 1] = 0;
+
+	pr_info("%s: Recording %s as primary, "
+		"but it has not been enslaved to %s yet.\n",
+		bond->dev->name, ifname, bond->dev->name);
 out:
 	write_unlock_bh(&bond->curr_slave_lock);
 	read_unlock(&bond->lock);