ipvs: changes related to service usecnt

	Change the usage of svc usecnt during command execution:

- we check if svc is registered but we do not need to hold usecnt
reference while under __ip_vs_mutex, only the packet handling needs
it during scheduling

- change __ip_vs_service_get to __ip_vs_service_find and
__ip_vs_svc_fwm_get to __ip_vs_svc_fwm_find because now caller
will increase svc->usecnt

- put common code that calls update_service in __ip_vs_update_dest

- put common code in ip_vs_unlink_service() and use it to unregister
the service

- add comment that svc should not be accessed after ip_vs_del_service
anymore

- all IP_VS_WAIT_WHILE calls are now unified: usecnt > 0

- Properly log the app ports

	As result, some problems are fixed:

- possible use-after-free of svc in ip_vs_genl_set_cmd after
ip_vs_del_service because our usecnt reference does not guarantee that
svc is not freed on refcnt==0, eg. when no dests are moved to trash

- possible usecnt leak in do_ip_vs_set_ctl after ip_vs_del_service
when the service is not freed now, for example, when some
destionations are moved into trash and svc->refcnt remains above 0.
It is harmless because svc is not in hash anymore.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Patrick McHardy <kaber@trash.net>

net/netfilter/ipvs/ip_vs_app.c

@@ -103,8 +103,8 @@ ip_vs_app_inc_new(struct ip_vs_app *app, __u16 proto, __u16 port)
 		goto out;
 
 	list_add(&inc->a_list, &app->incs_list);
-	IP_VS_DBG(9, "%s application %s:%u registered\n",
-		  pp->name, inc->name, inc->port);
+	IP_VS_DBG(9, "%s App %s:%u registered\n",
+		  pp->name, inc->name, ntohs(inc->port));
 
 	return 0;
 
@@ -130,7 +130,7 @@ ip_vs_app_inc_release(struct ip_vs_app *inc)
 		pp->unregister_app(inc);
 
 	IP_VS_DBG(9, "%s App %s:%u unregistered\n",
-		  pp->name, inc->name, inc->port);
+		  pp->name, inc->name, ntohs(inc->port));
 
 	list_del(&inc->a_list);