[133/151] net: Fix userspace RTM_NEWLINK notifications.

Greg KH
2009-12-17T04:12:48Z

commit d90a909e1f3e006a1d57fe11fd417173b6494701 upstream.

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

The problem was trivailly fixed by moving the userspace
notification from rtnetlink_event to the end of register_netdevice.

Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
net/core/dev.c | 11 +++++++++++
net/core/rtnetlink.c | 4 +---
2 files changed, 12 insertions(+), 3 deletions(-)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4860,6 +4860,11 @@ int register_netdevice(struct net_device
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;
@@ -5398,6 +5403,12 @@ int dev_change_net_namespace(struct net_
/* 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:
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1334,13 +1334,11 @@ static int rtnetlink_event(struct notifi
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_REGISTER:
case NETDEV_CHANGE:
case NETDEV_GOING_DOWN:
break;