commit 2b76b68c65c97fc11409088c3c30993324df8500
Author: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
Date:   Thu Jan 4 18:50:50 2018 +0100

    build: support for Linux 4.15
    
    Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>

diff --git a/extensions/pknock/xt_pknock.c b/extensions/pknock/xt_pknock.c
index 6fbdea4..31d4bc8 100644
--- a/extensions/pknock/xt_pknock.c
+++ b/extensions/pknock/xt_pknock.c
@@ -358,10 +358,20 @@ has_logged_during_this_minute(const struct peer *peer)
  * @r: rule
  */
 static void
-peer_gc(unsigned long r)
+peer_gc(
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 15, 0)
+	struct timer_list *tl
+#else
+	unsigned long r
+#endif
+)
 {
 	unsigned int i;
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 15, 0)
+	struct xt_pknock_rule *rule = from_timer(rule, tl, timer);
+#else
 	struct xt_pknock_rule *rule = (struct xt_pknock_rule *)r;
+#endif
 	struct peer *peer;
 	struct list_head *pos, *n;
 
@@ -469,9 +479,13 @@ add_rule(struct xt_pknock_mtinfo *info)
 	if (rule->peer_head == NULL)
 		goto out;
 
+#if LINUX_VERSION_CODE >= KERNEL_VERSION(4, 15, 0)
+	timer_setup(&rule->timer, peer_gc, 0);
+#else
 	init_timer(&rule->timer);
 	rule->timer.function	= peer_gc;
 	rule->timer.data	= (unsigned long)rule;
+#endif
 
 	rule->status_proc = proc_create_data(info->rule_name, 0, pde,
 	                    &pknock_proc_ops, rule);