netfilter: nf_nat_masquerade: add netns refcount tracker to masq_dev_work

If compiled with CONFIG_NET_NS_REFCNT_TRACKER=y,
using put_net_track() in iterate_cleanup_work()
and netns_tracker_alloc() in nf_nat_masq_schedule()
might help us finding netns refcount imbalances.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_nat_masquerade.c

@@ -12,6 +12,7 @@
 struct masq_dev_work {
 	struct work_struct work;
 	struct net *net;
+	netns_tracker ns_tracker;
 	union nf_inet_addr addr;
 	int ifindex;
 	int (*iter)(struct nf_conn *i, void *data);
@@ -82,7 +83,7 @@ static void iterate_cleanup_work(struct work_struct *work)
 
 	nf_ct_iterate_cleanup_net(w->net, w->iter, (void *)w, 0, 0);
 
-	put_net(w->net);
+	put_net_track(w->net, &w->ns_tracker);
 	kfree(w);
 	atomic_dec(&masq_worker_count);
 	module_put(THIS_MODULE);
@@ -119,6 +120,7 @@ static void nf_nat_masq_schedule(struct net *net, union nf_inet_addr *addr,
 		INIT_WORK(&w->work, iterate_cleanup_work);
 		w->ifindex = ifindex;
 		w->net = net;
+		netns_tracker_alloc(net, &w->ns_tracker, gfp_flags);
 		w->iter = iter;
 		if (addr)
 			w->addr = *addr;