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

Pull core timer changes from Ingo Molnar:
 "It contains continued generic-NOHZ work by Frederic and smaller
  cleanups."

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  time: Kill xtime_lock, replacing it with jiffies_lock
  clocksource: arm_generic: use this_cpu_ptr per-cpu helper
  clocksource: arm_generic: use integer math helpers
  time/jiffies: Make clocksource_jiffies static
  clocksource: clean up parse_pmtmr()
  tick: Correct the comments for tick_sched_timer()
  tick: Conditionally build nohz specific code in tick handler
  tick: Consolidate tick handling for high and low res handlers
  tick: Consolidate timekeeping handling code

5 files changed, 70 insertions, 92 deletions

diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c
index 6629bf7b528..7a925ba456f 100644
--- a/kernel/time/jiffies.c
+++ b/kernel/time/jiffies.c
@@ -58,7 +58,7 @@ static cycle_t jiffies_read(struct clocksource *cs)
         return (cycle_t) jiffies;
 }
 
-struct clocksource clocksource_jiffies = {
+static struct clocksource clocksource_jiffies = {
         .name           = "jiffies",
         .rating         = 1, /* lowest valid rating*/
         .read           = jiffies_read,
@@ -67,6 +67,8 @@ struct clocksource clocksource_jiffies = {
         .shift          = JIFFIES_SHIFT,
 };
 
+__cacheline_aligned_in_smp DEFINE_SEQLOCK(jiffies_lock);
+
 #if (BITS_PER_LONG < 64)
 u64 get_jiffies_64(void)
 {
@@ -74,9 +76,9 @@ u64 get_jiffies_64(void)
         u64 ret;
 
         do {
-                seq = read_seqbegin(&xtime_lock);
+                seq = read_seqbegin(&jiffies_lock);
                 ret = jiffies_64;
-        } while (read_seqretry(&xtime_lock, seq));
+        } while (read_seqretry(&jiffies_lock, seq));
         return ret;
 }
 EXPORT_SYMBOL(get_jiffies_64);
diff --git a/kernel/time/tick-common.c b/kernel/time/tick-common.c
index da6c9ecad4e..b1600a6973f 100644
--- a/kernel/time/tick-common.c
+++ b/kernel/time/tick-common.c
@@ -63,13 +63,13 @@ int tick_is_oneshot_available(void)
 static void tick_periodic(int cpu)
 {
         if (tick_do_timer_cpu == cpu) {
-                write_seqlock(&xtime_lock);
+                write_seqlock(&jiffies_lock);
 
                 /* Keep track of the next tick event */
                 tick_next_period = ktime_add(tick_next_period, tick_period);
 
                 do_timer(1);
-                write_sequnlock(&xtime_lock);
+                write_sequnlock(&jiffies_lock);
         }
 
         update_process_times(user_mode(get_irq_regs()));
@@ -130,9 +130,9 @@ void tick_setup_periodic(struct clock_event_device *dev, int broadcast)
                 ktime_t next;
 
                 do {
-                        seq = read_seqbegin(&xtime_lock);
+                        seq = read_seqbegin(&jiffies_lock);
                         next = tick_next_period;
-                } while (read_seqretry(&xtime_lock, seq));
+                } while (read_seqretry(&jiffies_lock, seq));
 
                 clockevents_set_mode(dev, CLOCK_EVT_MODE_ONESHOT);
 
diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h
index 4e265b901fe..cf3e59ed6dc 100644
--- a/kernel/time/tick-internal.h
+++ b/kernel/time/tick-internal.h
@@ -141,4 +141,3 @@ static inline int tick_device_is_functional(struct clock_event_device *dev)
 #endif
 
 extern void do_timer(unsigned long ticks);
-extern seqlock_t xtime_lock;
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 80e061a9ed0..d58e552d9fd 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -31,7 +31,7 @@
 static DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched);
 
 /*
- * The time, when the last jiffy update happened. Protected by xtime_lock.
+ * The time, when the last jiffy update happened. Protected by jiffies_lock.
  */
 static ktime_t last_jiffies_update;
 
@@ -49,14 +49,14 @@ static void tick_do_update_jiffies64(ktime_t now)
         ktime_t delta;
 
         /*
-         * Do a quick check without holding xtime_lock:
+         * Do a quick check without holding jiffies_lock:
          */
         delta = ktime_sub(now, last_jiffies_update);
         if (delta.tv64 < tick_period.tv64)
                 return;
 
-        /* Reevalute with xtime_lock held */
-        write_seqlock(&xtime_lock);
+        /* Reevalute with jiffies_lock held */
+        write_seqlock(&jiffies_lock);
 
         delta = ktime_sub(now, last_jiffies_update);
         if (delta.tv64 >= tick_period.tv64) {
@@ -79,7 +79,7 @@ static void tick_do_update_jiffies64(ktime_t now)
                 /* Keep the tick_next_period variable up to date */
                 tick_next_period = ktime_add(last_jiffies_update, tick_period);
         }
-        write_sequnlock(&xtime_lock);
+        write_sequnlock(&jiffies_lock);
 }
 
 /*
@@ -89,15 +89,58 @@ static ktime_t tick_init_jiffy_update(void)
 {
         ktime_t period;
 
-        write_seqlock(&xtime_lock);
+        write_seqlock(&jiffies_lock);
         /* Did we start the jiffies update yet ? */
         if (last_jiffies_update.tv64 == 0)
                 last_jiffies_update = tick_next_period;
         period = last_jiffies_update;
-        write_sequnlock(&xtime_lock);
+        write_sequnlock(&jiffies_lock);
         return period;
 }
 
+
+static void tick_sched_do_timer(ktime_t now)
+{
+        int cpu = smp_processor_id();
+
+#ifdef CONFIG_NO_HZ
+        /*
+         * Check if the do_timer duty was dropped. We don't care about
+         * concurrency: This happens only when the cpu in charge went
+         * into a long sleep. If two cpus happen to assign themself to
+         * this duty, then the jiffies update is still serialized by
+         * jiffies_lock.
+         */
+        if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
+                tick_do_timer_cpu = cpu;
+#endif
+
+        /* Check, if the jiffies need an update */
+        if (tick_do_timer_cpu == cpu)
+                tick_do_update_jiffies64(now);
+}
+
+static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs)
+{
+#ifdef CONFIG_NO_HZ
+        /*
+         * When we are idle and the tick is stopped, we have to touch
+         * the watchdog as we might not schedule for a really long
+         * time. This happens on complete idle SMP systems while
+         * waiting on the login prompt. We also increment the "start of
+         * idle" jiffy stamp so the idle accounting adjustment we do
+         * when we go busy again does not account too much ticks.
+         */
+        if (ts->tick_stopped) {
+                touch_softlockup_watchdog();
+                if (is_idle_task(current))
+                        ts->idle_jiffies++;
+        }
+#endif
+        update_process_times(user_mode(regs));
+        profile_tick(CPU_PROFILING);
+}
+
 /*
  * NOHZ - aka dynamic tick functionality
  */
@@ -282,11 +325,11 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
 
         /* Read jiffies and the time when jiffies were updated last */
         do {
-                seq = read_seqbegin(&xtime_lock);
+                seq = read_seqbegin(&jiffies_lock);
                 last_update = last_jiffies_update;
                 last_jiffies = jiffies;
                 time_delta = timekeeping_max_deferment();
-        } while (read_seqretry(&xtime_lock, seq));
+        } while (read_seqretry(&jiffies_lock, seq));
 
         if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || printk_needs_cpu(cpu) ||
             arch_needs_cpu(cpu)) {
@@ -652,40 +695,12 @@ static void tick_nohz_handler(struct clock_event_device *dev)
 {
         struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
         struct pt_regs *regs = get_irq_regs();
-        int cpu = smp_processor_id();
         ktime_t now = ktime_get();
 
         dev->next_event.tv64 = KTIME_MAX;
 
-        /*
-         * Check if the do_timer duty was dropped. We don't care about
-         * concurrency: This happens only when the cpu in charge went
-         * into a long sleep. If two cpus happen to assign themself to
-         * this duty, then the jiffies update is still serialized by
-         * xtime_lock.
-         */
-        if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
-                tick_do_timer_cpu = cpu;
-
-        /* Check, if the jiffies need an update */
-        if (tick_do_timer_cpu == cpu)
-                tick_do_update_jiffies64(now);
-
-        /*
-         * When we are idle and the tick is stopped, we have to touch
-         * the watchdog as we might not schedule for a really long
-         * time. This happens on complete idle SMP systems while
-         * waiting on the login prompt. We also increment the "start
-         * of idle" jiffy stamp so the idle accounting adjustment we
-         * do when we go busy again does not account too much ticks.
-         */
-        if (ts->tick_stopped) {
-                touch_softlockup_watchdog();
-                ts->idle_jiffies++;
-        }
-
-        update_process_times(user_mode(regs));
-        profile_tick(CPU_PROFILING);
+        tick_sched_do_timer(now);
+        tick_sched_handle(ts, regs);
 
         while (tick_nohz_reprogram(ts, now)) {
                 now = ktime_get();
@@ -806,45 +821,15 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
                 container_of(timer, struct tick_sched, sched_timer);
         struct pt_regs *regs = get_irq_regs();
         ktime_t now = ktime_get();
-        int cpu = smp_processor_id();
 
-#ifdef CONFIG_NO_HZ
-        /*
-         * Check if the do_timer duty was dropped. We don't care about
-         * concurrency: This happens only when the cpu in charge went
-         * into a long sleep. If two cpus happen to assign themself to
-         * this duty, then the jiffies update is still serialized by
-         * xtime_lock.
-         */
-        if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
-                tick_do_timer_cpu = cpu;
-#endif
-
-        /* Check, if the jiffies need an update */
-        if (tick_do_timer_cpu == cpu)
-                tick_do_update_jiffies64(now);
+        tick_sched_do_timer(now);
 
         /*
          * Do not call, when we are not in irq context and have
          * no valid regs pointer
          */
-        if (regs) {
-                /*
-                 * When we are idle and the tick is stopped, we have to touch
-                 * the watchdog as we might not schedule for a really long
-                 * time. This happens on complete idle SMP systems while
-                 * waiting on the login prompt. We also increment the "start of
-                 * idle" jiffy stamp so the idle accounting adjustment we do
-                 * when we go busy again does not account too much ticks.
-                 */
-                if (ts->tick_stopped) {
-                        touch_softlockup_watchdog();
-                        if (is_idle_task(current))
-                                ts->idle_jiffies++;
-                }
-                update_process_times(user_mode(regs));
-                profile_tick(CPU_PROFILING);
-        }
+        if (regs)
+                tick_sched_handle(ts, regs);
 
         hrtimer_forward(timer, now, tick_period);
 
@@ -878,7 +863,7 @@ void tick_setup_sched_timer(void)
         /* Get the next period (per cpu) */
         hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update());
 
-        /* Offset the tick to avert xtime_lock contention. */
+        /* Offset the tick to avert jiffies_lock contention. */
         if (sched_skew_tick) {
                 u64 offset = ktime_to_ns(tick_period) >> 1;
                 do_div(offset, num_possible_cpus());
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index e424970bb56..4c7de02eacd 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -25,12 +25,6 @@
 
 static struct timekeeper timekeeper;
 
-/*
- * This read-write spinlock protects us from races in SMP while
- * playing with xtime.
- */
-__cacheline_aligned_in_smp DEFINE_SEQLOCK(xtime_lock);
-
 /* flag for if timekeeping is suspended */
 int __read_mostly timekeeping_suspended;
 
@@ -1299,9 +1293,7 @@ struct timespec get_monotonic_coarse(void)
 }
 
 /*
- * The 64-bit jiffies value is not atomic - you MUST NOT read it
- * without sampling the sequence number in xtime_lock.
- * jiffies is defined in the linker script...
+ * Must hold jiffies_lock
  */
 void do_timer(unsigned long ticks)
 {
@@ -1389,7 +1381,7 @@ EXPORT_SYMBOL_GPL(ktime_get_monotonic_offset);
  */
 void xtime_update(unsigned long ticks)
 {
-        write_seqlock(&xtime_lock);
+        write_seqlock(&jiffies_lock);
         do_timer(ticks);
-        write_sequnlock(&xtime_lock);
+        write_sequnlock(&jiffies_lock);
 }