Merge git://git.infradead.org/users/dwmw2/atm

David Woodhouse says:

====================
This is the result of pulling on the thread started by Krzysztof Mazur's
original patch 'pppoatm: don't send frames to destroyed vcc'.

Various problems in the pppoatm and br2684 code are solved, some of which
were easily triggered and would panic the kernel.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>