net/decnet: Convert timers to use timer_setup()

In preparation for unconditionally passing the struct timer_list pointer to
all timer callbacks, switch to using the new timer_setup() and from_timer()
to pass the timer pointer explicitly.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: David Ahern <dsa@cumulusnetworks.com>
Cc: linux-decnet-user@lists.sourceforge.net
Cc: netdev@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/decnet/dn_dev.c b/net/decnet/dn_dev.c
index 4d339de..92dbaa3 100644
--- a/net/decnet/dn_dev.c
+++ b/net/decnet/dn_dev.c
@@ -1038,14 +1038,14 @@
 
 static void dn_dev_set_timer(struct net_device *dev);
 
-static void dn_dev_timer_func(unsigned long arg)
+static void dn_dev_timer_func(struct timer_list *t)
 {
-	struct net_device *dev = (struct net_device *)arg;
-	struct dn_dev *dn_db;
+	struct dn_dev *dn_db = from_timer(dn_db, t, timer);
+	struct net_device *dev;
 	struct dn_ifaddr *ifa;
 
 	rcu_read_lock();
-	dn_db = rcu_dereference(dev->dn_ptr);
+	dev = dn_db->dev;
 	if (dn_db->t3 <= dn_db->parms.t2) {
 		if (dn_db->parms.timer3) {
 			for (ifa = rcu_dereference(dn_db->ifa_list);
@@ -1070,8 +1070,6 @@
 	if (dn_db->parms.t2 > dn_db->parms.t3)
 		dn_db->parms.t2 = dn_db->parms.t3;
 
-	dn_db->timer.data = (unsigned long)dev;
-	dn_db->timer.function = dn_dev_timer_func;
 	dn_db->timer.expires = jiffies + (dn_db->parms.t2 * HZ);
 
 	add_timer(&dn_db->timer);
@@ -1100,7 +1098,7 @@
 
 	rcu_assign_pointer(dev->dn_ptr, dn_db);
 	dn_db->dev = dev;
-	init_timer(&dn_db->timer);
+	timer_setup(&dn_db->timer, dn_dev_timer_func, 0);
 
 	dn_db->uptime = jiffies;