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ipvlan: improvise dev_id generation logic in IPvlan

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The patch 009146d117 ("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>
This commit is contained in:
Mahesh Bandewar 2017-01-09 15:05:54 -08:00 committed by David S. Miller
parent de28c99d71
commit da36e13cf6
2 changed files with 13 additions and 1 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
drivers/net/ipvlan/ipvlan.h
View file

@ -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;

13
drivers/net/ipvlan/ipvlan_main.c
View file

@ -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