Merge branch 'timers-fixes-for-linus' of...

Merge branch 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  time: Fix accumulation bug triggered by long delay.
  posix-cpu-timers: Reset expire cache when no timer is running
  timer stats: Fix del_timer_sync() and try_to_del_timer_sync()
  clockevents: Sanitize min_delta_ns adjustment and prevent overflows

include/linux/clockchips.h

@@ -73,6 +73,7 @@ enum clock_event_nofitiers {
  * @list:		list head for the management code
  * @mode:		operating mode assigned by the management code
  * @next_event:		local storage for the next event in oneshot mode
+ * @retries:		number of forced programming retries
  */
 struct clock_event_device {
 	const char		*name;
@@ -93,6 +94,7 @@ struct clock_event_device {
 	struct list_head	list;
 	enum clock_event_mode	mode;
 	ktime_t			next_event;
+	unsigned long		retries;
 };
 
 /*

kernel/posix-cpu-timers.c

@@ -1061,9 +1061,9 @@ static void check_thread_timers(struct task_struct *tsk,
 	}
 }
 
-static void stop_process_timers(struct task_struct *tsk)
+static void stop_process_timers(struct signal_struct *sig)
 {
-	struct thread_group_cputimer *cputimer = &tsk->signal->cputimer;
+	struct thread_group_cputimer *cputimer = &sig->cputimer;
 	unsigned long flags;
 
 	if (!cputimer->running)
@@ -1072,6 +1072,10 @@ static void stop_process_timers(struct task_struct *tsk)
 	spin_lock_irqsave(&cputimer->lock, flags);
 	cputimer->running = 0;
 	spin_unlock_irqrestore(&cputimer->lock, flags);
+
+	sig->cputime_expires.prof_exp = cputime_zero;
+	sig->cputime_expires.virt_exp = cputime_zero;
+	sig->cputime_expires.sched_exp = 0;
 }
 
 static u32 onecputick;
@@ -1133,7 +1137,7 @@ static void check_process_timers(struct task_struct *tsk,
 	    list_empty(&timers[CPUCLOCK_VIRT]) &&
 	    cputime_eq(sig->it[CPUCLOCK_VIRT].expires, cputime_zero) &&
 	    list_empty(&timers[CPUCLOCK_SCHED])) {
-		stop_process_timers(tsk);
+		stop_process_timers(sig);
 		return;
 	}
 

kernel/time/tick-oneshot.c

@@ -22,6 +22,29 @@
 
 #include "tick-internal.h"
 
+/* Limit min_delta to a jiffie */
+#define MIN_DELTA_LIMIT		(NSEC_PER_SEC / HZ)
+
+static int tick_increase_min_delta(struct clock_event_device *dev)
+{
+	/* Nothing to do if we already reached the limit */
+	if (dev->min_delta_ns >= MIN_DELTA_LIMIT)
+		return -ETIME;
+
+	if (dev->min_delta_ns < 5000)
+		dev->min_delta_ns = 5000;
+	else
+		dev->min_delta_ns += dev->min_delta_ns >> 1;
+
+	if (dev->min_delta_ns > MIN_DELTA_LIMIT)
+		dev->min_delta_ns = MIN_DELTA_LIMIT;
+
+	printk(KERN_WARNING "CE: %s increased min_delta_ns to %llu nsec\n",
+	       dev->name ? dev->name : "?",
+	       (unsigned long long) dev->min_delta_ns);
+	return 0;
+}
+
 /**
  * tick_program_event internal worker function
  */
@@ -37,23 +60,28 @@ int tick_dev_program_event(struct clock_event_device *dev, ktime_t expires,
 		if (!ret || !force)
 			return ret;
 
+		dev->retries++;
 		/*
-		 * We tried 2 times to program the device with the given
-		 * min_delta_ns. If that's not working then we double it
+		 * We tried 3 times to program the device with the given
+		 * min_delta_ns. If that's not working then we increase it
 		 * and emit a warning.
 		 */
 		if (++i > 2) {
 			/* Increase the min. delta and try again */
-			if (!dev->min_delta_ns)
-				dev->min_delta_ns = 5000;
-			else
-				dev->min_delta_ns += dev->min_delta_ns >> 1;
-
+			if (tick_increase_min_delta(dev)) {
+				/*
+				 * Get out of the loop if min_delta_ns
+				 * hit the limit already. That's
+				 * better than staying here forever.
+				 *
+				 * We clear next_event so we have a
+				 * chance that the box survives.
+				 */
 				printk(KERN_WARNING
-			       "CE: %s increasing min_delta_ns to %llu nsec\n",
-			       dev->name ? dev->name : "?",
-			       (unsigned long long) dev->min_delta_ns << 1);
-
+				       "CE: Reprogramming failure. Giving up\n");
+				dev->next_event.tv64 = KTIME_MAX;
+				return -ETIME;
+			}
 			i = 0;
 		}
 

kernel/time/timekeeping.c

@@ -818,6 +818,7 @@ void update_wall_time(void)
 	shift = min(shift, maxshift);
 	while (offset >= timekeeper.cycle_interval) {
 		offset = logarithmic_accumulation(offset, shift);
+		if(offset < timekeeper.cycle_interval<<shift)
 			shift--;
 	}
 

kernel/time/timer_list.c

@@ -228,6 +228,7 @@ print_tickdevice(struct seq_file *m, struct tick_device *td, int cpu)
 	SEQ_printf(m, " event_handler:  ");
 	print_name_offset(m, dev->event_handler);
 	SEQ_printf(m, "\n");
+	SEQ_printf(m, " retries:        %lu\n", dev->retries);
 }
 
 static void timer_list_show_tickdevices(struct seq_file *m)
@@ -257,7 +258,7 @@ static int timer_list_show(struct seq_file *m, void *v)
 	u64 now = ktime_to_ns(ktime_get());
 	int cpu;
 
-	SEQ_printf(m, "Timer List Version: v0.5\n");
+	SEQ_printf(m, "Timer List Version: v0.6\n");
 	SEQ_printf(m, "HRTIMER_MAX_CLOCK_BASES: %d\n", HRTIMER_MAX_CLOCK_BASES);
 	SEQ_printf(m, "now at %Ld nsecs\n", (unsigned long long)now);
 

kernel/timer.c

@@ -880,6 +880,7 @@ int try_to_del_timer_sync(struct timer_list *timer)
 	if (base->running_timer == timer)
 		goto out;
 
+	timer_stats_timer_clear_start_info(timer);
 	ret = 0;
 	if (timer_pending(timer)) {
 		detach_timer(timer, 1);