From: Pavel Emelianov <redacted>
Date: Wed, 18 Apr 2007 12:16:18 +0400

The proposal it to make sock_orphan before detaching the callback
in netlink_release() and to check for the sock to be SOCK_DEAD in
netlink_dump_start() before setting a new callback.

As discussed in this thread there might be other ways to a
approach this, but this fix is good for now.

Patch applied, thank you.