4 files changed, 59 insertions, 3 deletions

diff --git a/kernel/relay.c b/kernel/relay.c
index 4c035a8a248c..d6204a485818 100644
--- a/kernel/relay.c
+++ b/kernel/relay.c
@@ -736,7 +736,7 @@ static int relay_file_open(struct inode *inode, struct file *filp)
         kref_get(&buf->kref);
         filp->private_data = buf;
 
-        return 0;
+        return nonseekable_open(inode, filp);
 }
 
 /**
@@ -1056,6 +1056,10 @@ static struct pipe_buf_operations relay_pipe_buf_ops = {
         .get = generic_pipe_buf_get,
 };
 
+static void relay_page_release(struct splice_pipe_desc *spd, unsigned int i)
+{
+}
+
 /*
  *      subbuf_splice_actor - splice up to one subbuf's worth of data
  */
@@ -1083,6 +1087,7 @@ static int subbuf_splice_actor(struct file *in,
                 .partial = partial,
                 .flags = flags,
                 .ops = &relay_pipe_buf_ops,
+                .spd_release = relay_page_release,
         };
 
         if (rbuf->subbufs_produced == rbuf->subbufs_consumed)
diff --git a/kernel/sched.c b/kernel/sched.c
index 28c73f07efb2..8dcdec6fe0fe 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1052,6 +1052,49 @@ static void resched_cpu(int cpu)
         resched_task(cpu_curr(cpu));
         spin_unlock_irqrestore(&rq->lock, flags);
 }
+
+#ifdef CONFIG_NO_HZ
+/*
+ * When add_timer_on() enqueues a timer into the timer wheel of an
+ * idle CPU then this timer might expire before the next timer event
+ * which is scheduled to wake up that CPU. In case of a completely
+ * idle system the next event might even be infinite time into the
+ * future. wake_up_idle_cpu() ensures that the CPU is woken up and
+ * leaves the inner idle loop so the newly added timer is taken into
+ * account when the CPU goes back to idle and evaluates the timer
+ * wheel for the next timer event.
+ */
+void wake_up_idle_cpu(int cpu)
+{
+        struct rq *rq = cpu_rq(cpu);
+
+        if (cpu == smp_processor_id())
+                return;
+
+        /*
+         * This is safe, as this function is called with the timer
+         * wheel base lock of (cpu) held. When the CPU is on the way
+         * to idle and has not yet set rq->curr to idle then it will
+         * be serialized on the timer wheel base lock and take the new
+         * timer into account automatically.
+         */
+        if (rq->curr != rq->idle)
+                return;
+
+        /*
+         * We can set TIF_RESCHED on the idle task of the other CPU
+         * lockless. The worst case is that the other CPU runs the
+         * idle task through an additional NOOP schedule()
+         */
+        set_tsk_thread_flag(rq->idle, TIF_NEED_RESCHED);
+
+        /* NEED_RESCHED must be visible before we test polling */
+        smp_mb();
+        if (!tsk_is_polling(rq->idle))
+                smp_send_reschedule(cpu);
+}
+#endif
+
 #else
 static void __resched_task(struct task_struct *p, int tif_bit)
 {
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
index 278534bbca95..7f60097d443a 100644
--- a/kernel/time/clocksource.c
+++ b/kernel/time/clocksource.c
@@ -174,7 +174,7 @@ static void clocksource_check_watchdog(struct clocksource *cs)
                         if (watchdog)
                                 del_timer(&watchdog_timer);
                         watchdog = cs;
-                        init_timer_deferrable(&watchdog_timer);
+                        init_timer(&watchdog_timer);
                         watchdog_timer.function = clocksource_watchdog;
 
                         /* Reset watchdog cycles */
diff --git a/kernel/timer.c b/kernel/timer.c
index 99b00a25f88b..b024106daa70 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -451,10 +451,18 @@ void add_timer_on(struct timer_list *timer, int cpu)
         spin_lock_irqsave(&base->lock, flags);
         timer_set_base(timer, base);
         internal_add_timer(base, timer);
+        /*
+         * Check whether the other CPU is idle and needs to be
+         * triggered to reevaluate the timer wheel when nohz is
+         * active. We are protected against the other CPU fiddling
+         * with the timer by holding the timer base lock. This also
+         * makes sure that a CPU on the way to idle can not evaluate
+         * the timer wheel.
+         */
+        wake_up_idle_cpu(cpu);
         spin_unlock_irqrestore(&base->lock, flags);
 }
 
-
 /**
  * mod_timer - modify a timer's timeout
  * @timer: the timer to be modified