1 files changed, 32 insertions, 9 deletions

diff --git a/kernel/timer.c b/kernel/timer.c
index efde11e197c4..97bf05baade7 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -90,8 +90,13 @@ static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
 
 /*
  * Note that all tvec_bases are 2 byte aligned and lower bit of
- * base in timer_list is guaranteed to be zero. Use the LSB for
- * the new flag to indicate whether the timer is deferrable
+ * base in timer_list is guaranteed to be zero. Use the LSB to
+ * indicate whether the timer is deferrable.
+ *
+ * A deferrable timer will work normally when the system is busy, but
+ * will not cause a CPU to come out of idle just to service it; instead,
+ * the timer will be serviced when the CPU eventually wakes up with a
+ * subsequent non-deferrable timer.
  */
 #define TBASE_DEFERRABLE_FLAG           (0x1)
 
@@ -321,6 +326,7 @@ EXPORT_SYMBOL_GPL(round_jiffies_up_relative);
 
 /**
  * set_timer_slack - set the allowed slack for a timer
+ * @timer: the timer to be modified
  * @slack_hz: the amount of time (in jiffies) allowed for rounding
  *
  * Set the amount of time, in jiffies, that a certain timer has
@@ -692,12 +698,8 @@ __mod_timer(struct timer_list *timer, unsigned long expires,
         cpu = smp_processor_id();
 
 #if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP)
-        if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu)) {
-                int preferred_cpu = get_nohz_load_balancer();
-
-                if (preferred_cpu >= 0)
-                        cpu = preferred_cpu;
-        }
+        if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu))
+                cpu = get_nohz_timer_target();
 #endif
         new_base = per_cpu(tvec_bases, cpu);
 
@@ -1302,7 +1304,6 @@ void run_local_timers(void)
 {
         hrtimer_run_queues();
         raise_softirq(TIMER_SOFTIRQ);
-        softlockup_tick();
 }
 
 /*
@@ -1763,3 +1764,25 @@ unsigned long msleep_interruptible(unsigned int msecs)
 }
 
 EXPORT_SYMBOL(msleep_interruptible);
+
+static int __sched do_usleep_range(unsigned long min, unsigned long max)
+{
+        ktime_t kmin;
+        unsigned long delta;
+
+        kmin = ktime_set(0, min * NSEC_PER_USEC);
+        delta = (max - min) * NSEC_PER_USEC;
+        return schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL);
+}
+
+/**
+ * usleep_range - Drop in replacement for udelay where wakeup is flexible
+ * @min: Minimum time in usecs to sleep
+ * @max: Maximum time in usecs to sleep
+ */
+void usleep_range(unsigned long min, unsigned long max)
+{
+        __set_current_state(TASK_UNINTERRUPTIBLE);
+        do_usleep_range(min, max);
+}
+EXPORT_SYMBOL(usleep_range);