timer: Pass timer_list pointer to callbacks unconditionally

Now that all timer callbacks are already taking their struct timer_list
pointer as the callback argument, just do this unconditionally and remove
the .data field.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

include/linux/timer.h

@@ -18,7 +18,6 @@ struct timer_list {
 	struct hlist_node	entry;
 	unsigned long		expires;
 	void			(*function)(unsigned long);
-	unsigned long		data;
 	u32			flags;
 
 #ifdef CONFIG_LOCKDEP
@@ -70,7 +69,6 @@ struct timer_list {
 #define __TIMER_INITIALIZER(_function, _data, _flags) {		\
 		.entry = { .next = TIMER_ENTRY_STATIC },	\
 		.function = (_function),			\
-		.data = (_data),				\
 		.flags = (_flags),				\
 		__TIMER_LOCKDEP_MAP_INITIALIZER(		\
 			__FILE__ ":" __stringify(__LINE__))	\
@@ -121,14 +119,12 @@ static inline void init_timer_on_stack_key(struct timer_list *timer,
 	do {								\
 		__init_timer((_timer), (_flags));			\
 		(_timer)->function = (_fn);				\
-		(_timer)->data = (_data);				\
 	} while (0)
 
 #define __setup_timer_on_stack(_timer, _fn, _data, _flags)		\
 	do {								\
 		__init_timer_on_stack((_timer), (_flags));		\
 		(_timer)->function = (_fn);				\
-		(_timer)->data = (_data);				\
 	} while (0)
 
 #ifndef CONFIG_LOCKDEP

kernel/time/timer.c

@@ -1107,12 +1107,12 @@ EXPORT_SYMBOL(timer_reduce);
  * add_timer - start a timer
  * @timer: the timer to be added
  *
- * The kernel will do a ->function(->data) callback from the
+ * The kernel will do a ->function(@timer) callback from the
  * timer interrupt at the ->expires point in the future. The
  * current time is 'jiffies'.
  *
- * The timer's ->expires, ->function (and if the handler uses it, ->data)
+ * The timer's ->expires, ->function fields must be set prior calling this
- * fields must be set prior calling this function.
+ * function.
  *
  * Timers with an ->expires field in the past will be executed in the next
  * timer tick.
@@ -1284,8 +1284,7 @@ int del_timer_sync(struct timer_list *timer)
 EXPORT_SYMBOL(del_timer_sync);
 #endif
 
-static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long),
+static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long))
-			  unsigned long data)
 {
 	int count = preempt_count();
 
@@ -1309,7 +1308,7 @@ static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long),
 	lock_map_acquire(&lockdep_map);
 
 	trace_timer_expire_entry(timer);
-	fn(data);
+	fn((TIMER_DATA_TYPE)timer);
 	trace_timer_expire_exit(timer);
 
 	lock_map_release(&lockdep_map);
@@ -1332,7 +1331,6 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head)
 	while (!hlist_empty(head)) {
 		struct timer_list *timer;
 		void (*fn)(unsigned long);
-		unsigned long data;
 
 		timer = hlist_entry(head->first, struct timer_list, entry);
 
@@ -1340,15 +1338,14 @@ static void expire_timers(struct timer_base *base, struct hlist_head *head)
 		detach_timer(timer, true);
 
 		fn = timer->function;
-		data = timer->data;
 
 		if (timer->flags & TIMER_IRQSAFE) {
 			raw_spin_unlock(&base->lock);
-			call_timer_fn(timer, fn, data);
+			call_timer_fn(timer, fn);
 			raw_spin_lock(&base->lock);
 		} else {
 			raw_spin_unlock_irq(&base->lock);
-			call_timer_fn(timer, fn, data);
+			call_timer_fn(timer, fn);
 			raw_spin_lock_irq(&base->lock);
 		}
 	}