rcu: 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: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>

kernel/rcu/rcutorture.c

@@ -1076,7 +1076,7 @@ static void rcu_torture_timer_cb(struct rcu_head *rhp)
  * counter in the element should never be greater than 1, otherwise, the
  * RCU implementation is broken.
  */
-static void rcu_torture_timer(unsigned long unused)
+static void rcu_torture_timer(struct timer_list *unused)
 {
 	int idx;
 	unsigned long started;
@@ -1163,7 +1163,7 @@ rcu_torture_reader(void *arg)
 	VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
 	set_user_nice(current, MAX_NICE);
 	if (irqreader && cur_ops->irq_capable)
-		setup_timer_on_stack(&t, rcu_torture_timer, 0);
+		timer_setup_on_stack(&t, rcu_torture_timer, 0);
 
 	do {
 		if (irqreader && cur_ops->irq_capable) {

kernel/rcu/tree_plugin.h

@@ -2261,9 +2261,11 @@ static void do_nocb_deferred_wakeup_common(struct rcu_data *rdp)
 }
 
 /* Do a deferred wakeup of rcu_nocb_kthread() from a timer handler. */
-static void do_nocb_deferred_wakeup_timer(unsigned long x)
+static void do_nocb_deferred_wakeup_timer(struct timer_list *t)
 {
-	do_nocb_deferred_wakeup_common((struct rcu_data *)x);
+	struct rcu_data *rdp = from_timer(rdp, t, nocb_timer);
+
+	do_nocb_deferred_wakeup_common(rdp);
 }
 
 /*
@@ -2327,8 +2329,7 @@ static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp)
 	init_swait_queue_head(&rdp->nocb_wq);
 	rdp->nocb_follower_tail = &rdp->nocb_follower_head;
 	raw_spin_lock_init(&rdp->nocb_lock);
-	setup_timer(&rdp->nocb_timer, do_nocb_deferred_wakeup_timer,
-		    (unsigned long)rdp);
+	timer_setup(&rdp->nocb_timer, do_nocb_deferred_wakeup_timer, 0);
 }
 
 /*