Hi,

Attached a patch to use a slab for expectations, I think that this could 
increase a bit the performance in a system which has lots of expectations.

I also moved the increment of an expectation refcount to 
ip_conntrack_expect_alloc because we could use ip_conntrack_expect_put 
to release an expectation which we just allocated in a helper (well, in 
current helpers I didn't find any case but there are weird protocols 
outthere so I think that it's not a bad idea).

Patrick, if you consider that it's ok, would you be willing to add this 
to pom-ng? If I'm missing something, please let me know.

regards,
Pablo