3 files changed, 13 insertions, 5 deletions

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index ab80515008f4..ffca825d24bc 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -300,11 +300,10 @@ EXPORT_SYMBOL_GPL(ktime_sub_ns);
  */
 u64 ktime_divns(const ktime_t kt, s64 div)
 {
-        u64 dclc, inc, dns;
+        u64 dclc;
         int sft = 0;
 
-        dclc = dns = ktime_to_ns(kt);
-        inc = div;
+        dclc = ktime_to_ns(kt);
         /* Make sure the divisor is less than 2^32: */
         while (div >> 32) {
                 sft++;
@@ -632,8 +631,6 @@ void clock_was_set(void)
  */
 void hres_timers_resume(void)
 {
-        WARN_ON_ONCE(num_online_cpus() > 1);
-
         /* Retrigger the CPU local events: */
         retrigger_next_event(NULL);
 }
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index f1525ad06cb3..c42a03aef36f 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -1037,6 +1037,9 @@ static void check_thread_timers(struct task_struct *tsk,
                                 sig->rlim[RLIMIT_RTTIME].rlim_cur +=
                                                                 USEC_PER_SEC;
                         }
+                        printk(KERN_INFO
+                                "RT Watchdog Timeout: %s[%d]\n",
+                                tsk->comm, task_pid_nr(tsk));
                         __group_send_sig_info(SIGXCPU, SEND_SIG_PRIV, tsk);
                 }
         }
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index b854a895591e..86baa4f0dfe4 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -48,6 +48,13 @@ static void tick_do_update_jiffies64(ktime_t now)
         unsigned long ticks = 0;
         ktime_t delta;
 
+        /*
+         * Do a quick check without holding xtime_lock:
+         */
+        delta = ktime_sub(now, last_jiffies_update);
+        if (delta.tv64 < tick_period.tv64)
+                return;
+
         /* Reevalute with xtime_lock held */
         write_seqlock(&xtime_lock);
 
@@ -228,6 +235,7 @@ void tick_nohz_stop_sched_tick(void)
                                local_softirq_pending());
                         ratelimit++;
                 }
+                goto end;
         }
 
         ts->idle_calls++;