[PATCH] hrtimers: remove data field

The nanosleep cleanup allows to remove the data field of hrtimer.  The
callback function can use container_of() to get it's own data.  Since the
hrtimer structure is anyway embedded in other structures, this adds no
overhead.

Signed-off-by: Roman Zippel <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: Roman Zippel

fs/exec.c

@@ -632,7 +632,7 @@ static int de_thread(struct task_struct *tsk)
 		 * synchronize with any firing (by calling del_timer_sync)
 		 * before we can safely let the old group leader die.
 		 */
-		sig->real_timer.data = current;
+		sig->tsk = current;
 		spin_unlock_irq(lock);
 		if (hrtimer_cancel(&sig->real_timer))
 			hrtimer_restart(&sig->real_timer);

include/linux/hrtimer.h

@@ -45,18 +45,15 @@ struct hrtimer_base;
  * @expires:	the absolute expiry time in the hrtimers internal
  *		representation. The time is related to the clock on
  *		which the timer is based.
- * @state:	state of the timer
  * @function:	timer expiry callback function
- * @data:	argument for the callback function
  * @base:	pointer to the timer base (per cpu and per clock)
  *
  * The hrtimer structure must be initialized by init_hrtimer_#CLOCKTYPE()
  */
 struct hrtimer {
 	struct rb_node		node;
 	ktime_t			expires;
-	int			(*function)(void *);
-	void			*data;
+	int			(*function)(struct hrtimer *);
 	struct hrtimer_base	*base;
 };
 

include/linux/sched.h

@@ -402,6 +402,7 @@ struct signal_struct {
 
 	/* ITIMER_REAL timer for the process */
 	struct hrtimer real_timer;
+	struct task_struct *tsk;
 	ktime_t it_real_incr;
 
 	/* ITIMER_PROF and ITIMER_VIRTUAL timers for the process */

include/linux/timer.h

@@ -96,6 +96,7 @@ static inline void add_timer(struct timer_list *timer)
 
 extern void init_timers(void);
 extern void run_local_timers(void);
-extern int it_real_fn(void *);
+struct hrtimer;
+extern int it_real_fn(struct hrtimer *);
 
 #endif

kernel/fork.c

@@ -848,7 +848,7 @@ static inline int copy_signal(unsigned long clone_flags, struct task_struct * ts
 	hrtimer_init(&sig->real_timer, CLOCK_MONOTONIC, HRTIMER_REL);
 	sig->it_real_incr.tv64 = 0;
 	sig->real_timer.function = it_real_fn;
-	sig->real_timer.data = tsk;
+	sig->tsk = tsk;
 
 	sig->it_virt_expires = cputime_zero;
 	sig->it_virt_incr = cputime_zero;

kernel/hrtimer.c

@@ -613,21 +613,19 @@ static inline void run_hrtimer_queue(struct hrtimer_base *base)
 
 	while ((node = base->first)) {
 		struct hrtimer *timer;
-		int (*fn)(void *);
+		int (*fn)(struct hrtimer *);
 		int restart;
-		void *data;
 
 		timer = rb_entry(node, struct hrtimer, node);
 		if (base->softirq_time.tv64 <= timer->expires.tv64)
 			break;
 
 		fn = timer->function;
-		data = timer->data;
 		set_curr_timer(base, timer);
 		__remove_hrtimer(timer, base);
 		spin_unlock_irq(&base->lock);
 
-		restart = fn(data);
+		restart = fn(timer);
 
 		spin_lock_irq(&base->lock);
 
@@ -664,9 +662,10 @@ struct sleep_hrtimer {
 	int expired;
 };
 
-static int nanosleep_wakeup(void *data)
+static int nanosleep_wakeup(struct hrtimer *timer)
 {
-	struct sleep_hrtimer *t = data;
+	struct sleep_hrtimer *t =
+		container_of(timer, struct sleep_hrtimer, timer);
 
 	t->expired = 1;
 	wake_up_process(t->task);
@@ -677,7 +676,6 @@ static int nanosleep_wakeup(void *data)
 static int __sched do_nanosleep(struct sleep_hrtimer *t, enum hrtimer_mode mode)
 {
 	t->timer.function = nanosleep_wakeup;
-	t->timer.data = t;
 	t->task = current;
 	t->expired = 0;
 

kernel/itimer.c

@@ -128,17 +128,16 @@ asmlinkage long sys_getitimer(int which, struct itimerval __user *value)
 /*
  * The timer is automagically restarted, when interval != 0
  */
-int it_real_fn(void *data)
+int it_real_fn(struct hrtimer *timer)
 {
-	struct task_struct *tsk = (struct task_struct *) data;
+	struct signal_struct *sig =
+	    container_of(timer, struct signal_struct, real_timer);
 
-	send_group_sig_info(SIGALRM, SEND_SIG_PRIV, tsk);
-
-	if (tsk->signal->it_real_incr.tv64 != 0) {
-		hrtimer_forward(&tsk->signal->real_timer,
-				tsk->signal->real_timer.base->softirq_time,
-				tsk->signal->it_real_incr);
+	send_group_sig_info(SIGALRM, SEND_SIG_PRIV, sig->tsk);
 
+	if (sig->it_real_incr.tv64 != 0) {
+		hrtimer_forward(timer, timer->base->softirq_time,
+				sig->it_real_incr);
 		return HRTIMER_RESTART;
 	}
 	return HRTIMER_NORESTART;

kernel/posix-timers.c

@@ -145,7 +145,7 @@ static int common_timer_set(struct k_itimer *, int,
 			    struct itimerspec *, struct itimerspec *);
 static int common_timer_del(struct k_itimer *timer);
 
-static int posix_timer_fn(void *data);
+static int posix_timer_fn(struct hrtimer *data);
 
 static struct k_itimer *lock_timer(timer_t timer_id, unsigned long *flags);
 
@@ -334,14 +334,14 @@ EXPORT_SYMBOL_GPL(posix_timer_event);
 
  * This code is for CLOCK_REALTIME* and CLOCK_MONOTONIC* timers.
  */
-static int posix_timer_fn(void *data)
+static int posix_timer_fn(struct hrtimer *timer)
 {
-	struct k_itimer *timr = data;
-	struct hrtimer *timer = &timr->it.real.timer;
+	struct k_itimer *timr;
 	unsigned long flags;
 	int si_private = 0;
 	int ret = HRTIMER_NORESTART;
 
+	timr = container_of(timer, struct k_itimer, it.real.timer);
 	spin_lock_irqsave(&timr->it_lock, flags);
 
 	if (timr->it.real.interval.tv64 != 0)
@@ -725,7 +725,6 @@ common_timer_set(struct k_itimer *timr, int flags,
 
 	mode = flags & TIMER_ABSTIME ? HRTIMER_ABS : HRTIMER_REL;
 	hrtimer_init(&timr->it.real.timer, timr->it_clock, mode);
-	timr->it.real.timer.data = timr;
 	timr->it.real.timer.function = posix_timer_fn;
 
 	timer->expires = timespec_to_ktime(new_setting->it_value);