Re: [PATCH V2] IPv6 : add multicast routing verify which net_device is lo

From: Gao feng <redacted>
Date: Tue, 20 Dec 2011 19:10:24 +0800

In currently routing subsystem, when we lookup a multicast routing
to send muticast packets to outside, rt6_device_match will return
the rt6_info which it's match first. If we add a multicast route on
loopback devices beforce the others interface, rt6_device_match will
retrun the rt6_info which rt6i_dev->name is "lo". But, obviously,
we can't send a muticast packet to outside using loopback devices.
It case all multicast packets blocking.

Commit 4af04aba93f47699e disabled kernel add multicast route on lo
automatically. However,  we can't surmise the routing-add order or
interdict add multicast routing on loopback devices in user space.
The bug still exist. So, i think, more stronger routing subsystem is
necessary.

Signed-off-by: Wang xingtong <redacted>

Ok, this is getting rediculious.  I want to revert all of this
stuff.

How about, instead, we stop userland adding explicit addresses to the
loopback device since that's what started behaving differently
recently and causes these problems in the first place?