1 files changed, 49 insertions, 5 deletions

diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index 529143b4c8d2..59225b484e4e 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -46,6 +46,14 @@ ktime_t tick_period;
  *    procedure also covers cpu hotplug.
  */
 int tick_do_timer_cpu __read_mostly = TICK_DO_TIMER_BOOT;
+#ifdef CONFIG_NO_HZ_FULL
+/*
+ * tick_do_timer_boot_cpu indicates the boot CPU temporarily owns
+ * tick_do_timer_cpu and it should be taken over by an eligible secondary
+ * when one comes online.
+ */
+static int tick_do_timer_boot_cpu __read_mostly = -1;
+#endif
 
 /*
  * Debugging: see timer_list.c
@@ -149,7 +157,7 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
             !tick_broadcast_oneshot_active()) {
                 clockevents_switch_state(dev, CLOCK_EVT_STATE_PERIODIC);
         } else {
-                unsigned long seq;
+                unsigned int seq;
                 ktime_t next;
 
                 do {
@@ -167,6 +175,26 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
         }
 }
 
+#ifdef CONFIG_NO_HZ_FULL
+static void giveup_do_timer(void *info)
+{
+        int cpu = *(unsigned int *)info;
+
+        WARN_ON(tick_do_timer_cpu != smp_processor_id());
+
+        tick_do_timer_cpu = cpu;
+}
+
+static void tick_take_do_timer_from_boot(void)
+{
+        int cpu = smp_processor_id();
+        int from = tick_do_timer_boot_cpu;
+
+        if (from >= 0 && from != cpu)
+                smp_call_function_single(from, giveup_do_timer, &cpu, 1);
+}
+#endif
+
 /*
  * Setup the tick device
  */
@@ -186,12 +214,26 @@ static void tick_setup_device(struct tick_device *td,
                  * this cpu:
                  */
                 if (tick_do_timer_cpu == TICK_DO_TIMER_BOOT) {
-                        if (!tick_nohz_full_cpu(cpu))
-                                tick_do_timer_cpu = cpu;
-                        else
-                                tick_do_timer_cpu = TICK_DO_TIMER_NONE;
+                        tick_do_timer_cpu = cpu;
+
                         tick_next_period = ktime_get();
                         tick_period = NSEC_PER_SEC / HZ;
+#ifdef CONFIG_NO_HZ_FULL
+                        /*
+                         * The boot CPU may be nohz_full, in which case set
+                         * tick_do_timer_boot_cpu so the first housekeeping
+                         * secondary that comes up will take do_timer from
+                         * us.
+                         */
+                        if (tick_nohz_full_cpu(cpu))
+                                tick_do_timer_boot_cpu = cpu;
+
+                } else if (tick_do_timer_boot_cpu != -1 &&
+                                                !tick_nohz_full_cpu(cpu)) {
+                        tick_take_do_timer_from_boot();
+                        tick_do_timer_boot_cpu = -1;
+                        WARN_ON(tick_do_timer_cpu != cpu);
+#endif
                 }
 
                 /*
@@ -487,6 +529,7 @@ void tick_freeze(void)
                 trace_suspend_resume(TPS("timekeeping_freeze"),
                                      smp_processor_id(), true);
                 system_state = SYSTEM_SUSPEND;
+                sched_clock_suspend();
                 timekeeping_suspend();
         } else {
                 tick_suspend_local();
@@ -510,6 +553,7 @@ void tick_unfreeze(void)
 
         if (tick_freeze_depth == num_online_cpus()) {
                 timekeeping_resume();
+                sched_clock_resume();
                 system_state = SYSTEM_RUNNING;
                 trace_suspend_resume(TPS("timekeeping_freeze"),
                                      smp_processor_id(), false);