1 files changed, 47 insertions, 1 deletions

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 2b6e1757aedd..14bc9cfa6399 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -418,8 +418,19 @@ hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
         /* Switch the timer base, if necessary: */
         new_base = switch_hrtimer_base(timer, base);
 
-        if (mode == HRTIMER_REL)
+        if (mode == HRTIMER_REL) {
                 tim = ktime_add(tim, new_base->get_time());
+                /*
+                 * CONFIG_TIME_LOW_RES is a temporary way for architectures
+                 * to signal that they simply return xtime in
+                 * do_gettimeoffset(). In this case we want to round up by
+                 * resolution when starting a relative timer, to avoid short
+                 * timeouts. This will go away with the GTOD framework.
+                 */
+#ifdef CONFIG_TIME_LOW_RES
+                tim = ktime_add(tim, base->resolution);
+#endif
+        }
         timer->expires = tim;
 
         enqueue_hrtimer(timer, new_base);
@@ -494,6 +505,41 @@ ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
         return rem;
 }
 
+#ifdef CONFIG_NO_IDLE_HZ
+/**
+ * hrtimer_get_next_event - get the time until next expiry event
+ *
+ * Returns the delta to the next expiry event or KTIME_MAX if no timer
+ * is pending.
+ */
+ktime_t hrtimer_get_next_event(void)
+{
+        struct hrtimer_base *base = __get_cpu_var(hrtimer_bases);
+        ktime_t delta, mindelta = { .tv64 = KTIME_MAX };
+        unsigned long flags;
+        int i;
+
+        for (i = 0; i < MAX_HRTIMER_BASES; i++, base++) {
+                struct hrtimer *timer;
+
+                spin_lock_irqsave(&base->lock, flags);
+                if (!base->first) {
+                        spin_unlock_irqrestore(&base->lock, flags);
+                        continue;
+                }
+                timer = rb_entry(base->first, struct hrtimer, node);
+                delta.tv64 = timer->expires.tv64;
+                spin_unlock_irqrestore(&base->lock, flags);
+                delta = ktime_sub(delta, base->get_time());
+                if (delta.tv64 < mindelta.tv64)
+                        mindelta.tv64 = delta.tv64;
+        }
+        if (mindelta.tv64 < 0)
+                mindelta.tv64 = 0;
+        return mindelta;
+}
+#endif
+
 /**
  * hrtimer_init - initialize a timer to the given clock
  *