Bug#599816: Nested GRE locking bug

[David Miller <davem@davemloft.net>]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 14 Oct 2010 06:11:59 +0200

> net-next-2.6 contains a fix for this, adding the perc_cpu
> xmit_recursion limit. We might push it to net-2.6

We need to think a bit more about this.

We are essentially now saying that one can only configure
tunnels 3 levels deep, and no more.

I can guarentee you someone out there uses at least 4,
perhaps more.

And those people will be broken by the new limit.

So putting this into net-2.6 with such a low limit will
be quite dangerous.