diff --git a/include/linux/timer.h b/include/linux/timer.h
index ec86e4e55ea3..c5a3ff799c56 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -190,6 +190,10 @@ extern void add_timer_on(struct timer_list *timer, int cpu);
 extern int del_timer(struct timer_list * timer);
 extern int mod_timer(struct timer_list *timer, unsigned long expires);
 extern int mod_timer_pending(struct timer_list *timer, unsigned long expires);
+#ifdef CONFIG_SMP
+extern bool check_pending_deferrable_timers(int cpu);
+#endif
+extern int timer_reduce(struct timer_list *timer, unsigned long expires);
 
 /*
  * The jiffies value which is added to now, when there is no timer
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 29d07ce6e833..f250c6841b75 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -963,8 +963,11 @@ static struct timer_base *lock_timer_base(struct timer_list *timer,
 	}
 }
 
+#define MOD_TIMER_PENDING_ONLY		0x01
+#define MOD_TIMER_REDUCE		0x02
+
 static inline int
-__mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
+__mod_timer(struct timer_list *timer, unsigned long expires, unsigned int options)
 {
 	struct timer_base *base, *new_base;
 	unsigned int idx = UINT_MAX;
@@ -984,7 +987,11 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
 		 * larger granularity than you would get from adding a new
 		 * timer with this expiry.
 		 */
-		if (timer->expires == expires)
+		long diff = timer->expires - expires;
+
+		if (!diff)
+			return 1;
+		if (options & MOD_TIMER_REDUCE && diff <= 0)
 			return 1;
 
 		/*
@@ -996,6 +1003,12 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
 		base = lock_timer_base(timer, &flags);
 		forward_timer_base(base);
 
+		if (timer_pending(timer) && (options & MOD_TIMER_REDUCE) &&
+		    time_before_eq(timer->expires, expires)) {
+			ret = 1;
+			goto out_unlock;
+		}
+
 		clk = base->clk;
 		idx = calc_wheel_index(expires, clk);
 
@@ -1005,7 +1018,10 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
 		 * subsequent call will exit in the expires check above.
 		 */
 		if (idx == timer_get_idx(timer)) {
-			timer->expires = expires;
+			if (!(options & MOD_TIMER_REDUCE))
+				timer->expires = expires;
+			else if (time_after(timer->expires, expires))
+				timer->expires = expires;
 			ret = 1;
 			goto out_unlock;
 		}
@@ -1017,7 +1033,7 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
 	timer_stats_timer_set_start_info(timer);
 
 	ret = detach_if_pending(timer, base, false);
-	if (!ret && pending_only)
+	if (!ret && (options & MOD_TIMER_PENDING_ONLY))
 		goto out_unlock;
 
 	new_base = get_target_base(base, timer->flags);
@@ -1078,7 +1094,7 @@ out_unlock:
  */
 int mod_timer_pending(struct timer_list *timer, unsigned long expires)
 {
-	return __mod_timer(timer, expires, true);
+	return __mod_timer(timer, expires, MOD_TIMER_PENDING_ONLY);
 }
 EXPORT_SYMBOL(mod_timer_pending);
 
@@ -1104,10 +1120,25 @@ EXPORT_SYMBOL(mod_timer_pending);
  */
 int mod_timer(struct timer_list *timer, unsigned long expires)
 {
-	return __mod_timer(timer, expires, false);
+	return __mod_timer(timer, expires, 0);
 }
 EXPORT_SYMBOL(mod_timer);
 
+/**
+ * timer_reduce - Modify a timer's timeout if it would reduce the timeout
+ * @timer:	The timer to be modified
+ * @expires:	New timeout in jiffies
+ *
+ * timer_reduce() is very similar to mod_timer(), except that it will only
+ * modify a running timer if that would reduce the expiration time (it will
+ * start a timer that isn't running).
+ */
+int timer_reduce(struct timer_list *timer, unsigned long expires)
+{
+	return __mod_timer(timer, expires, MOD_TIMER_REDUCE);
+}
+EXPORT_SYMBOL(timer_reduce);
+
 /**
  * add_timer - start a timer
  * @timer: the timer to be added
@@ -1795,7 +1826,7 @@ signed long __sched schedule_timeout(signed long timeout)
 	expire = timeout + jiffies;
 
 	setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
-	__mod_timer(&timer, expire, false);
+	__mod_timer(&timer, expire, 0);
 	schedule();
 	del_singleshot_timer_sync(&timer);