1 files changed, 27 insertions, 4 deletions

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index d55092ceee29..3ab28993f6e0 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -234,6 +234,11 @@ again:
                         goto again;
                 }
                 timer->base = new_base;
+        } else {
+                if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
+                        cpu = this_cpu;
+                        goto again;
+                }
         }
         return new_base;
 }
@@ -569,6 +574,23 @@ hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
 
         cpu_base->expires_next.tv64 = expires_next.tv64;
 
+        /*
+         * If a hang was detected in the last timer interrupt then we
+         * leave the hang delay active in the hardware. We want the
+         * system to make progress. That also prevents the following
+         * scenario:
+         * T1 expires 50ms from now
+         * T2 expires 5s from now
+         *
+         * T1 is removed, so this code is called and would reprogram
+         * the hardware to 5s from now. Any hrtimer_start after that
+         * will not reprogram the hardware due to hang_detected being
+         * set. So we'd effectivly block all timers until the T2 event
+         * fires.
+         */
+        if (cpu_base->hang_detected)
+                return;
+
         if (cpu_base->expires_next.tv64 != KTIME_MAX)
                 tick_program_event(cpu_base->expires_next, 1);
 }
@@ -968,11 +990,8 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
         /* Remove an active timer from the queue: */
         ret = remove_hrtimer(timer, base);
 
-        /* Switch the timer base, if necessary: */
-        new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
-
         if (mode & HRTIMER_MODE_REL) {
-                tim = ktime_add_safe(tim, new_base->get_time());
+                tim = ktime_add_safe(tim, base->get_time());
                 /*
                  * CONFIG_TIME_LOW_RES is a temporary way for architectures
                  * to signal that they simply return xtime in
@@ -987,6 +1006,9 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 
         hrtimer_set_expires_range_ns(timer, tim, delta_ns);
 
+        /* Switch the timer base, if necessary: */
+        new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
+
         timer_stats_hrtimer_set_start_info(timer);
 
         leftmost = enqueue_hrtimer(timer, new_base);
@@ -1017,6 +1039,7 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 
         return ret;
 }
+EXPORT_SYMBOL_GPL(__hrtimer_start_range_ns);
 
 /**
  * hrtimer_start_range_ns - (re)start an hrtimer on the current CPU