On Fri, 2012-04-27 at 14:28 -0400, Benjamin Poirier wrote:

I think that the rcu usage in this code is pointless. It should either be
removed or, if it was intended to protect against something, it ought to make
that clear.

1) The code does not make use of the deferred deletion/wait for completion rcu
api (ie. synchronize_rcu(), call_rcu()).
2) It does not benefit from the barriers implied by the rcu primitives used.
The code deals with callback pointers. There's no need to order writes to the
function code (!) before writes to the function pointers here.
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At a first glance, this seems pretty wrong.

code can disappear under you, thats for sure.

CONFIG_NF_CT_NETLINK=m

hint : module unload contains an rcu barrier.