Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull the leap second fixes from Thomas Gleixner:
 "It's a rather large series, but well discussed, refined and reviewed.
  It got a massive testing by John, Prarit and tip.

  In theory we could split it into two parts.  The first two patches

    f55a6faa3843: hrtimer: Provide clock_was_set_delayed()
    4873fa070ae8: timekeeping: Fix leapsecond triggered load spike issue

  are merely preventing the stuff loops forever issues, which people
  have observed.

  But there is no point in delaying the other 4 commits which achieve
  full correctness into 3.6 as they are tagged for stable anyway.  And I
  rather prefer to have the full fixes merged in bulk than a "prevent
  the observable wreckage and deal with the hidden fallout later"
  approach."

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  hrtimer: Update hrtimer base offsets each hrtimer_interrupt
  timekeeping: Provide hrtimer update function
  hrtimers: Move lock held region in hrtimer_interrupt()
  timekeeping: Maintain ktime_t based offsets for hrtimers
  timekeeping: Fix leapsecond triggered load spike issue
  hrtimer: Provide clock_was_set_delayed()

2 files changed, 98 insertions, 18 deletions

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index ae34bf51682b..6db7a5ed52b5 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -657,6 +657,14 @@ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
         return 0;
 }
 
+static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
+{
+        ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
+        ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
+
+        return ktime_get_update_offsets(offs_real, offs_boot);
+}
+
 /*
  * Retrigger next event is called after clock was set
  *
@@ -665,22 +673,12 @@ static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
 static void retrigger_next_event(void *arg)
 {
         struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases);
-        struct timespec realtime_offset, xtim, wtm, sleep;
 
         if (!hrtimer_hres_active())
                 return;
 
-        /* Optimized out for !HIGH_RES */
-        get_xtime_and_monotonic_and_sleep_offset(&xtim, &wtm, &sleep);
-        set_normalized_timespec(&realtime_offset, -wtm.tv_sec, -wtm.tv_nsec);
-
-        /* Adjust CLOCK_REALTIME offset */
         raw_spin_lock(&base->lock);
-        base->clock_base[HRTIMER_BASE_REALTIME].offset =
-                timespec_to_ktime(realtime_offset);
-        base->clock_base[HRTIMER_BASE_BOOTTIME].offset =
-                timespec_to_ktime(sleep);
-
+        hrtimer_update_base(base);
         hrtimer_force_reprogram(base, 0);
         raw_spin_unlock(&base->lock);
 }
@@ -710,13 +708,25 @@ static int hrtimer_switch_to_hres(void)
                 base->clock_base[i].resolution = KTIME_HIGH_RES;
 
         tick_setup_sched_timer();
-
         /* "Retrigger" the interrupt to get things going */
         retrigger_next_event(NULL);
         local_irq_restore(flags);
         return 1;
 }
 
+/*
+ * Called from timekeeping code to reprogramm the hrtimer interrupt
+ * device. If called from the timer interrupt context we defer it to
+ * softirq context.
+ */
+void clock_was_set_delayed(void)
+{
+        struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
+
+        cpu_base->clock_was_set = 1;
+        __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+}
+
 #else
 
 static inline int hrtimer_hres_active(void) { return 0; }
@@ -1250,11 +1260,10 @@ void hrtimer_interrupt(struct clock_event_device *dev)
         cpu_base->nr_events++;
         dev->next_event.tv64 = KTIME_MAX;
 
-        entry_time = now = ktime_get();
+        raw_spin_lock(&cpu_base->lock);
+        entry_time = now = hrtimer_update_base(cpu_base);
 retry:
         expires_next.tv64 = KTIME_MAX;
-
-        raw_spin_lock(&cpu_base->lock);
         /*
          * We set expires_next to KTIME_MAX here with cpu_base->lock
          * held to prevent that a timer is enqueued in our queue via
@@ -1330,8 +1339,12 @@ retry:
          * We need to prevent that we loop forever in the hrtimer
          * interrupt routine. We give it 3 attempts to avoid
          * overreacting on some spurious event.
+         *
+         * Acquire base lock for updating the offsets and retrieving
+         * the current time.
          */
-        now = ktime_get();
+        raw_spin_lock(&cpu_base->lock);
+        now = hrtimer_update_base(cpu_base);
         cpu_base->nr_retries++;
         if (++retries < 3)
                 goto retry;
@@ -1343,6 +1356,7 @@ retry:
          */
         cpu_base->nr_hangs++;
         cpu_base->hang_detected = 1;
+        raw_spin_unlock(&cpu_base->lock);
         delta = ktime_sub(now, entry_time);
         if (delta.tv64 > cpu_base->max_hang_time.tv64)
                 cpu_base->max_hang_time = delta;
@@ -1395,6 +1409,13 @@ void hrtimer_peek_ahead_timers(void)
 
 static void run_hrtimer_softirq(struct softirq_action *h)
 {
+        struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
+
+        if (cpu_base->clock_was_set) {
+                cpu_base->clock_was_set = 0;
+                clock_was_set();
+        }
+
         hrtimer_peek_ahead_timers();
 }
 
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 6f46a00a1e8a..269b1fe5f2ae 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -70,6 +70,12 @@ struct timekeeper {
         /* The raw monotonic time for the CLOCK_MONOTONIC_RAW posix clock. */
         struct timespec raw_time;
 
+        /* Offset clock monotonic -> clock realtime */
+        ktime_t offs_real;
+
+        /* Offset clock monotonic -> clock boottime */
+        ktime_t offs_boot;
+
         /* Seqlock for all timekeeper values */
         seqlock_t lock;
 };
@@ -172,6 +178,14 @@ static inline s64 timekeeping_get_ns_raw(void)
         return clocksource_cyc2ns(cycle_delta, clock->mult, clock->shift);
 }
 
+static void update_rt_offset(void)
+{
+        struct timespec tmp, *wtm = &timekeeper.wall_to_monotonic;
+
+        set_normalized_timespec(&tmp, -wtm->tv_sec, -wtm->tv_nsec);
+        timekeeper.offs_real = timespec_to_ktime(tmp);
+}
+
 /* must hold write on timekeeper.lock */
 static void timekeeping_update(bool clearntp)
 {
@@ -179,6 +193,7 @@ static void timekeeping_update(bool clearntp)
                 timekeeper.ntp_error = 0;
                 ntp_clear();
         }
+        update_rt_offset();
         update_vsyscall(&timekeeper.xtime, &timekeeper.wall_to_monotonic,
                          timekeeper.clock, timekeeper.mult);
 }
@@ -604,6 +619,7 @@ void __init timekeeping_init(void)
         }
         set_normalized_timespec(&timekeeper.wall_to_monotonic,
                                 -boot.tv_sec, -boot.tv_nsec);
+        update_rt_offset();
         timekeeper.total_sleep_time.tv_sec = 0;
         timekeeper.total_sleep_time.tv_nsec = 0;
         write_sequnlock_irqrestore(&timekeeper.lock, flags);
@@ -612,6 +628,12 @@ void __init timekeeping_init(void)
 /* time in seconds when suspend began */
 static struct timespec timekeeping_suspend_time;
 
+static void update_sleep_time(struct timespec t)
+{
+        timekeeper.total_sleep_time = t;
+        timekeeper.offs_boot = timespec_to_ktime(t);
+}
+
 /**
  * __timekeeping_inject_sleeptime - Internal function to add sleep interval
  * @delta: pointer to a timespec delta value
@@ -630,8 +652,7 @@ static void __timekeeping_inject_sleeptime(struct timespec *delta)
         timekeeper.xtime = timespec_add(timekeeper.xtime, *delta);
         timekeeper.wall_to_monotonic =
                         timespec_sub(timekeeper.wall_to_monotonic, *delta);
-        timekeeper.total_sleep_time = timespec_add(
-                                        timekeeper.total_sleep_time, *delta);
+        update_sleep_time(timespec_add(timekeeper.total_sleep_time, *delta));
 }
 
 
@@ -963,6 +984,8 @@ static cycle_t logarithmic_accumulation(cycle_t offset, int shift)
                 leap = second_overflow(timekeeper.xtime.tv_sec);
                 timekeeper.xtime.tv_sec += leap;
                 timekeeper.wall_to_monotonic.tv_sec -= leap;
+                if (leap)
+                        clock_was_set_delayed();
         }
 
         /* Accumulate raw time */
@@ -1079,6 +1102,8 @@ static void update_wall_time(void)
                 leap = second_overflow(timekeeper.xtime.tv_sec);
                 timekeeper.xtime.tv_sec += leap;
                 timekeeper.wall_to_monotonic.tv_sec -= leap;
+                if (leap)
+                        clock_was_set_delayed();
         }
 
         timekeeping_update(false);
@@ -1246,6 +1271,40 @@ void get_xtime_and_monotonic_and_sleep_offset(struct timespec *xtim,
         } while (read_seqretry(&timekeeper.lock, seq));
 }
 
+#ifdef CONFIG_HIGH_RES_TIMERS
+/**
+ * ktime_get_update_offsets - hrtimer helper
+ * @offs_real:  pointer to storage for monotonic -> realtime offset
+ * @offs_boot:  pointer to storage for monotonic -> boottime offset
+ *
+ * Returns current monotonic time and updates the offsets
+ * Called from hrtimer_interupt() or retrigger_next_event()
+ */
+ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot)
+{
+        ktime_t now;
+        unsigned int seq;
+        u64 secs, nsecs;
+
+        do {
+                seq = read_seqbegin(&timekeeper.lock);
+
+                secs = timekeeper.xtime.tv_sec;
+                nsecs = timekeeper.xtime.tv_nsec;
+                nsecs += timekeeping_get_ns();
+                /* If arch requires, add in gettimeoffset() */
+                nsecs += arch_gettimeoffset();
+
+                *offs_real = timekeeper.offs_real;
+                *offs_boot = timekeeper.offs_boot;
+        } while (read_seqretry(&timekeeper.lock, seq));
+
+        now = ktime_add_ns(ktime_set(secs, 0), nsecs);
+        now = ktime_sub(now, *offs_real);
+        return now;
+}
+#endif
+
 /**
  * ktime_get_monotonic_offset() - get wall_to_monotonic in ktime_t format
  */