From: Hannes Frederic Sowa <redacted>
Date: Thu, 27 Mar 2014 18:28:07 +0100

addrconf_join_solict and addrconf_join_anycast may cause actions which
need rtnl locked, especially on first address creation.

A new DAD state is introduced which deferres processing of the initial
DAD processing into a workqueue.

To get rtnl lock we need to push the code paths which depend on those
calls up to workqueues, specifically addrconf_verify and the DAD
processing.

(v2)
addrconf_dad_failure needs to be queued up to the workqueue, too. This
patch introduces a new DAD state and stop the DAD processing in the
workqueue (this is because of the possible ipv6_del_addr processing
which removes the solicited multicast address from the device).

addrconf_verify_lock is removed, too. After the transition it is not
needed any more.

As we are not processing in bottom half anymore we need to be a bit more
careful about disabling bottom half out when we lock spin_locks which are also
used in bh.

Relevant backtrace:

 ...

Hunks and backtrace stolen from a patch by Stephen Hemminger.

Reported-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: Hannes Frederic Sowa <redacted>
---
v3 (only minor change):
* reword pr_notice in inet6_ifa_finish_destroy (thanks, David!)

Applied, thanks a lot Hannes.