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Commit da36e13c authored by Mahesh Bandewar's avatar Mahesh Bandewar Committed by David S. Miller
Browse files

ipvlan: improvise dev_id generation logic in IPvlan 



The patch 009146d1 ("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: 009146d1 ("ipvlan: assign unique dev-id for each slave device.")
Signed-off-by: default avatarMahesh Bandewar <maheshb@google.com>
CC: Eric Dumazet <edumazet@google.com>
CC: David Miller <davem@davemloft.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent de28c99d

drivers/net/ipvlan/ipvlan.h

+1 −0
Original line number Diff line number Diff line
@@ -94,6 +94,7 @@ struct ipvl_port { 
	struct hlist_head	hlhead[IPVLAN_HASH_SIZE];

	struct list_head	ipvlans;

	u16			mode;

	u16			dev_id_start;

	struct work_struct	wq;

	struct sk_buff_head	backlog;

	int			count;

drivers/net/ipvlan/ipvlan_main.c

+12 −1
Original line number Diff line number Diff line
@@ -120,6 +120,7 @@ static int ipvlan_port_create(struct net_device *dev) 
	skb_queue_head_init(&port->backlog);

	INIT_WORK(&port->wq, ipvlan_process_multicast);

	ida_init(&port->ida);

	port->dev_id_start = 1;



	err = netdev_rx_handler_register(dev, ipvlan_handle_frame, port);

	if (err)
@@ -534,15 +535,25 @@ static int ipvlan_link_new(struct net *src_net, struct net_device *dev, 
	ipvlan_adjust_mtu(ipvlan, phy_dev);

	INIT_LIST_HEAD(&ipvlan->addrs);



	/* If the port-id base is at the MAX value, then wrap it around and

	 * begin from 0x1 again. This may be due to a busy system where lots

	 * of slaves are getting created and deleted.

	 */

	if (port->dev_id_start == 0xFFFE)

		port->dev_id_start = 0x1;



	/* Since L2 address is shared among all IPvlan slaves including

	 * master, use unique 16 bit dev-ids to diffentiate among them.

	 * Assign IDs between 0x1 and 0xFFFE (used by the master) to each

	 * slave link [see addrconf_ifid_eui48()].

	 */

	err = ida_simple_get(&port->ida, 1, 0xFFFE, GFP_KERNEL);

	err = ida_simple_get(&port->ida, port->dev_id_start, 0xFFFE,

			     GFP_KERNEL);

	if (err < 0)

		goto destroy_ipvlan_port;

	dev->dev_id = err;

	/* Increment id-base to the next slot for the future assignment */

	port->dev_id_start = err + 1;



	/* TODO Probably put random address here to be presented to the

	 * world but keep using the physical-dev address for the outgoing