Subject: Re: [PATCH] net: Fix userspace RTM_NEWLINK notifications.

From: Marcel Holtmann <[email-masked]>
Date: Mon, 14 Dec 2009 03:05:36 +0100

Hi Eric,

> 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.

the POST_INIT and UNREGISTER_BATCH are not 2.6.32 features. They are
2.6.33 features and thus you need to create a separate patch for -stable
if you wanna fix the /proc access issue.

Regards

Marcel