[patch] Race condition #2 in arch/ppc/cpm2_io/fcc_enet.c

[Stefan Nickl]

The initialisation sequence of the fcc ethernet driver contains race
condition that will crash the machine when a packet is received in the
wrong moment during system boot.

The oops usually shows ip_route_input() as the responsible function, but
that is not where things go wrong.
The problem is that when fec_enet_init() calls init_fcc_startup() during
device setup, fcc_restart() enables the receiver and the device will
start to receive packets while the rest of networking is not yet
prepared for this -> crash.
This situation can easily be created when the system is loaded with a
flood ping during boot, it will almost certainly crash (ping the
broadcast address on a isolated network to be sure the booting device
really gets it's share).

The patch moves the calls to fcc_restart() to fcc_enet_open(), so
packets will only start to come in when the kernel is ready for it.

I'm not 100% about all the implications this could have, but it seems to
work fine.

-- 
Stefan Nickl
Kontron Modular Computers

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