Re: [PATCH RFC 1/2] netfilter: conntrack: remove RCU usage in conntrack notifier

Eric Dumazet
2012-04-27T18:59:04Z

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.
> ---

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.