[tproxy] Deadlock in tproxy

[Daniel]

I think there is deadlock in tproxy. Two CPUs will wait for each other, ip_conntrack_lock and ip_nat_lock will never be unlocked.
To reproduce this deadlock, we need ftp traffic(or other traffic which yields expect) and iptable_tproxy loaded.

Plz see call trace below:

CPU0 call trace:

run_timer_softirq <-- invoked by timer
death_by_timeout <-- write_lock_bh(&ip_conntrack_lock)
clean_from_lists
remove_expectations
unexpect_related
__unexpect_related
ip_conntrack_expect_put
ip_conntrack_expect_destroyed <-- hooked by nat_reservation patch
#######
#ifdef CONFIG_IP_NF_NAT_NRES
        ip_conntrack_expect_destroyed = &ip_nat_reserved_cleanup_expect;
#endif
#######
ip_nat_reserved_cleanup_expect
ip_nat_reserved_unregister_all <-- write_lock_bh(&ip_nat_lock) ##failed##
[waiting...]

CPU1 call trace:

ip_tproxy_fn
ip_tproxy_setup_nat
ip_tproxy_setup_nat_bidir <-- write_lock_bh(&ip_nat_lock)
ip_nat_setup_info
ip_conntrack_alter_reply <-- write_lock_bh(&ip_conntrack_lock) ##failed##
[waiting...]