timer: Remove redundant __setup_timer*() macros

With __init_timer*() now matching __setup_timer*(), remove the redundant
internal interface, clean up the resulting definitions and add more
documentation.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Shaohua Li <shli@fb.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Kees Cook <keescook@chromium.org>

include/linux/kthread.h

@@ -164,9 +164,9 @@ extern void __kthread_init_worker(struct kthread_worker *worker,
 #define kthread_init_delayed_work(dwork, fn)				\
 	do {								\
 		kthread_init_work(&(dwork)->work, (fn));		\
-		__setup_timer(&(dwork)->timer,				\
-			      (TIMER_FUNC_TYPE)kthread_delayed_work_timer_fn,\
-			      TIMER_IRQSAFE);				\
+		__init_timer(&(dwork)->timer,				\
+			     kthread_delayed_work_timer_fn,		\
+			     TIMER_IRQSAFE);				\
 	} while (0)
 
 int kthread_worker_fn(void *worker_ptr);

include/linux/timer.h

@@ -78,6 +78,9 @@ struct timer_list {
 	struct timer_list _name =				\
 		__TIMER_INITIALIZER((TIMER_FUNC_TYPE)_function, 0)
 
+/*
+ * LOCKDEP and DEBUG timer interfaces.
+ */
 void init_timer_key(struct timer_list *timer,
 		    void (*func)(struct timer_list *), unsigned int flags,
 		    const char *name, struct lock_class_key *key);
@@ -87,9 +90,7 @@ extern void init_timer_on_stack_key(struct timer_list *timer,
 				    void (*func)(struct timer_list *),
 				    unsigned int flags, const char *name,
 				    struct lock_class_key *key);
-extern void destroy_timer_on_stack(struct timer_list *timer);
 #else
-static inline void destroy_timer_on_stack(struct timer_list *timer) { }
 static inline void init_timer_on_stack_key(struct timer_list *timer,
 					   void (*func)(struct timer_list *),
 					   unsigned int flags,
@@ -120,43 +121,26 @@ static inline void init_timer_on_stack_key(struct timer_list *timer,
 	init_timer_on_stack_key((_timer), (_fn), (_flags), NULL, NULL)
 #endif
 
-#define __setup_timer(_timer, _fn, _flags)				\
-	do {								\
-		__init_timer((_timer), (_fn), (_flags));		\
-	} while (0)
-
-#define __setup_timer_on_stack(_timer, _fn, _flags)			\
-	do {								\
-		__init_timer_on_stack((_timer), (_fn), (_flags));	\
-	} while (0)
+/**
+ * timer_setup - prepare a timer for first use
+ * @timer: the timer in question
+ * @callback: the function to call when timer expires
+ * @flags: any TIMER_* flags
+ *
+ * Regular timer initialization should use either DEFINE_TIMER() above,
+ * or timer_setup(). For timers on the stack, timer_setup_on_stack() must
+ * be used and must be balanced with a call to destroy_timer_on_stack().
+ */
+#define timer_setup(timer, callback, flags)			\
+	__init_timer((timer), (callback), (flags))
 
-#ifndef CONFIG_LOCKDEP
-static inline void timer_setup(struct timer_list *timer,
-			       void (*callback)(struct timer_list *),
-			       unsigned int flags)
-{
-	__setup_timer(timer, (TIMER_FUNC_TYPE)callback, flags);
-}
+#define timer_setup_on_stack(timer, callback, flags)		\
+	__init_timer_on_stack((timer), (callback), (flags))
 
-static inline void timer_setup_on_stack(struct timer_list *timer,
-			       void (*callback)(struct timer_list *),
-			       unsigned int flags)
-{
-	__setup_timer_on_stack(timer, (TIMER_FUNC_TYPE)callback, flags);
-}
+#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
+extern void destroy_timer_on_stack(struct timer_list *timer);
 #else
-/*
- * Under LOCKDEP, the timer lock_class_key (set up in __init_timer) needs
- * to be tied to the caller's context, so an inline (above) won't work. We
- * do want to keep the inline for argument type checking, though.
- */
-# define timer_setup(timer, callback, flags)				\
-		__setup_timer((timer), (TIMER_FUNC_TYPE)(callback),	\
-			      (flags))
-# define timer_setup_on_stack(timer, callback, flags)			\
-		__setup_timer_on_stack((timer),				\
-				       (TIMER_FUNC_TYPE)(callback),	\
-				       (flags))
+static inline void destroy_timer_on_stack(struct timer_list *timer) { }
 #endif
 
 #define from_timer(var, callback_timer, timer_fieldname) \

include/linux/workqueue.h

@@ -241,17 +241,17 @@ static inline unsigned int work_static(struct work_struct *work) { return 0; }
 #define __INIT_DELAYED_WORK(_work, _func, _tflags)			\
 	do {								\
 		INIT_WORK(&(_work)->work, (_func));			\
-		__setup_timer(&(_work)->timer,				\
-			      (TIMER_FUNC_TYPE)delayed_work_timer_fn,	\
-			      (_tflags) | TIMER_IRQSAFE);		\
+		__init_timer(&(_work)->timer,				\
+			     delayed_work_timer_fn,			\
+			     (_tflags) | TIMER_IRQSAFE);		\
 	} while (0)
 
 #define __INIT_DELAYED_WORK_ONSTACK(_work, _func, _tflags)		\
 	do {								\
 		INIT_WORK_ONSTACK(&(_work)->work, (_func));		\
-		__setup_timer_on_stack(&(_work)->timer,			\
-				       (TIMER_FUNC_TYPE)delayed_work_timer_fn,\
-				       (_tflags) | TIMER_IRQSAFE);	\
+		__init_timer_on_stack(&(_work)->timer,			\
+				      delayed_work_timer_fn,		\
+				      (_tflags) | TIMER_IRQSAFE);	\
 	} while (0)
 
 #define INIT_DELAYED_WORK(_work, _func)					\