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net: Fix userspace RTM_NEWLINK notifications.

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I received some bug reports about userspace programs having problems
because after RTM_NEWLINK was received they could not immediate access
files under /proc/sys/net/ because they had not been registered yet.

The original problem was trivially fixed by moving the userspace
notification from rtnetlink_event() to the end of
register_netdevice().

When testing that change I discovered I was still getting RTM_NEWLINK
events before I could access proc and I was also getting RTM_NEWLINK
events after I was seeing RTM_DELLINK.  Things practically guaranteed
to confuse userspace.

After a little more investigation these extra notifications proved to
be from the new notifiers NETDEV_POST_INIT and NETDEV_UNREGISTER_BATCH
hitting the default case in rtnetlink_event, and triggering
unnecessary RTM_NEWLINK messages.

rtnetlink_event now explicitly handles NETDEV_UNREGISTER_BATCH and
NETDEV_POST_INIT to avoid sending the incorrect userspace
notifications.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric W. Biederman 2009-12-12 22:11:15 +00:00 committed by David S. Miller
parent 5781b2356c
commit d90a909e1f
2 changed files with 14 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
net/core/dev.c
View file

@ -5035,6 +5035,11 @@ int register_netdevice(struct net_device *dev)
rollback_registered(dev);
dev->reg_state = NETREG_UNREGISTERED;
}
/*
* Prevent userspace races by waiting until the network
* device is fully setup before sending notifications.
*/
rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);
out:
return ret;
@ -5597,6 +5602,12 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char
/* Notify protocols, that a new device appeared. */
call_netdevice_notifiers(NETDEV_REGISTER, dev);
/*
* Prevent userspace races by waiting until the network
* device is fully setup before sending notifications.
*/
rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);
synchronize_net();
err = 0;
out:

6
net/core/rtnetlink.c
View file

@ -1364,15 +1364,15 @@ static int rtnetlink_event(struct notifier_block *this, unsigned long event, voi
case NETDEV_UNREGISTER:
rtmsg_ifinfo(RTM_DELLINK, dev, ~0U);
break;
case NETDEV_REGISTER:
rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);
break;
case NETDEV_UP:
case NETDEV_DOWN:
rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
break;
case NETDEV_POST_INIT:
case NETDEV_REGISTER:
case NETDEV_CHANGE:
case NETDEV_GOING_DOWN:
case NETDEV_UNREGISTER_BATCH:
break;
default:
rtmsg_ifinfo(RTM_NEWLINK, dev, 0);