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ipvlan: improvise dev_id generation logic in IPvlan
The patch009146d117
("ipvlan: assign unique dev-id for each slave device.") used ida_simple_get() to generate dev_ids assigned to the slave devices. However (Eric has pointed out that) there is a shortcoming with that approach as it always uses the first available ID. This becomes a problem when a slave gets deleted and a new slave gets added. The ID gets reassigned causing the new slave to get the same link-local address. This side-effect is undesirable. This patch adds a per-port variable that keeps track of the IDs assigned and used as the stat-base for the IDR api. This base will be wrapped around when it reaches the MAX (0xFFFE) value possibly on a busy system where slaves are added and deleted routinely. Fixes:009146d117
("ipvlan: assign unique dev-id for each slave device.") Signed-off-by: Mahesh Bandewar <maheshb@google.com> CC: Eric Dumazet <edumazet@google.com> CC: David Miller <davem@davemloft.org> Signed-off-by: David S. Miller <davem@davemloft.net>
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de28c99d71
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2 changed files with 13 additions and 1 deletions
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@ -94,6 +94,7 @@ struct ipvl_port {
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struct hlist_head hlhead[IPVLAN_HASH_SIZE];
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struct list_head ipvlans;
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u16 mode;
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u16 dev_id_start;
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struct work_struct wq;
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struct sk_buff_head backlog;
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int count;
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@ -120,6 +120,7 @@ static int ipvlan_port_create(struct net_device *dev)
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skb_queue_head_init(&port->backlog);
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INIT_WORK(&port->wq, ipvlan_process_multicast);
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ida_init(&port->ida);
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port->dev_id_start = 1;
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err = netdev_rx_handler_register(dev, ipvlan_handle_frame, port);
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if (err)
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@ -534,15 +535,25 @@ static int ipvlan_link_new(struct net *src_net, struct net_device *dev,
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ipvlan_adjust_mtu(ipvlan, phy_dev);
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INIT_LIST_HEAD(&ipvlan->addrs);
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/* If the port-id base is at the MAX value, then wrap it around and
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* begin from 0x1 again. This may be due to a busy system where lots
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* of slaves are getting created and deleted.
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*/
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if (port->dev_id_start == 0xFFFE)
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port->dev_id_start = 0x1;
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/* Since L2 address is shared among all IPvlan slaves including
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* master, use unique 16 bit dev-ids to diffentiate among them.
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* Assign IDs between 0x1 and 0xFFFE (used by the master) to each
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* slave link [see addrconf_ifid_eui48()].
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*/
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err = ida_simple_get(&port->ida, 1, 0xFFFE, GFP_KERNEL);
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err = ida_simple_get(&port->ida, port->dev_id_start, 0xFFFE,
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GFP_KERNEL);
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if (err < 0)
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goto destroy_ipvlan_port;
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dev->dev_id = err;
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/* Increment id-base to the next slot for the future assignment */
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port->dev_id_start = err + 1;
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/* TODO Probably put random address here to be presented to the
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* world but keep using the physical-dev address for the outgoing
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