/*
   *  linux/kernel/hrtimer.c
   *

   *  Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>

   *  Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar

   *  Copyright(C) 2006-2007  Timesys Corp., Thomas Gleixner

   *
   *  High-resolution kernel timers
   *
   *  In contrast to the low-resolution timeout API implemented in
   *  kernel/timer.c, hrtimers provide finer resolution and accuracy
   *  depending on system configuration and capabilities.
   *
   *  These timers are currently used for:
   *   - itimers
   *   - POSIX timers
   *   - nanosleep
   *   - precise in-kernel timing
   *
   *  Started by: Thomas Gleixner and Ingo Molnar
   *
   *  Credits:
   *	based on kernel/timer.c
   *

   *	Help, testing, suggestions, bugfixes, improvements were
   *	provided by:
   *
   *	George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
   *	et. al.
   *

   *  For licencing details see kernel-base/COPYING
   */
  
  #include <linux/cpu.h>
  #include <linux/module.h>
  #include <linux/percpu.h>
  #include <linux/hrtimer.h>
  #include <linux/notifier.h>
  #include <linux/syscalls.h>

  #include <linux/kallsyms.h>

  #include <linux/interrupt.h>

  #include <linux/tick.h>

  #include <linux/seq_file.h>
  #include <linux/err.h>

  #include <linux/debugobjects.h>

  #include <linux/sched.h>
  #include <linux/timer.h>

  
  #include <asm/uaccess.h>

  #include <trace/events/timer.h>

  /*
   * The timer bases:

   *
   * Note: If we want to add new timer bases, we have to skip the two
   * clock ids captured by the cpu-timers. We do this by holding empty
   * entries rather than doing math adjustment of the clock ids.
   * This ensures that we capture erroneous accesses to these clock ids
   * rather than moving them into the range of valid clock id's.

   */

  DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =

  {

  
  	.clock_base =

  	{

  		{
  			.index = CLOCK_REALTIME,
  			.get_time = &ktime_get_real,

  			.resolution = KTIME_LOW_RES,

  		},
  		{
  			.index = CLOCK_MONOTONIC,
  			.get_time = &ktime_get,

  			.resolution = KTIME_LOW_RES,

  		},
  	}

  };

  /*

   * Get the coarse grained time at the softirq based on xtime and
   * wall_to_monotonic.
   */

  static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base)

  {
  	ktime_t xtim, tomono;

  	struct timespec xts, tom;

  	unsigned long seq;
  
  	do {
  		seq = read_seqbegin(&xtime_lock);

  		xts = current_kernel_time();

  		tom = wall_to_monotonic;

  	} while (read_seqretry(&xtime_lock, seq));

  	xtim = timespec_to_ktime(xts);

  	tomono = timespec_to_ktime(tom);

  	base->clock_base[CLOCK_REALTIME].softirq_time = xtim;
  	base->clock_base[CLOCK_MONOTONIC].softirq_time =
  		ktime_add(xtim, tomono);

  }
  
  /*

   * Functions and macros which are different for UP/SMP systems are kept in a
   * single place
   */
  #ifdef CONFIG_SMP

  /*
   * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
   * means that all timers which are tied to this base via timer->base are
   * locked, and the base itself is locked too.
   *
   * So __run_timers/migrate_timers can safely modify all timers which could
   * be found on the lists/queues.
   *
   * When the timer's base is locked, and the timer removed from list, it is
   * possible to set timer->base = NULL and drop the lock: the timer remains
   * locked.
   */

  static
  struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
  					     unsigned long *flags)

  {

  	struct hrtimer_clock_base *base;

  
  	for (;;) {
  		base = timer->base;
  		if (likely(base != NULL)) {

  			raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);

  			if (likely(base == timer->base))
  				return base;
  			/* The timer has migrated to another CPU: */

  			raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);

  		}
  		cpu_relax();
  	}
  }

  
  /*
   * Get the preferred target CPU for NOHZ
   */
  static int hrtimer_get_target(int this_cpu, int pinned)
  {
  #ifdef CONFIG_NO_HZ
  	if (!pinned && get_sysctl_timer_migration() && idle_cpu(this_cpu)) {
  		int preferred_cpu = get_nohz_load_balancer();
  
  		if (preferred_cpu >= 0)
  			return preferred_cpu;
  	}
  #endif
  	return this_cpu;
  }
  
  /*
   * With HIGHRES=y we do not migrate the timer when it is expiring
   * before the next event on the target cpu because we cannot reprogram
   * the target cpu hardware and we would cause it to fire late.
   *
   * Called with cpu_base->lock of target cpu held.
   */
  static int
  hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
  {
  #ifdef CONFIG_HIGH_RES_TIMERS
  	ktime_t expires;
  
  	if (!new_base->cpu_base->hres_active)
  		return 0;
  
  	expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
  	return expires.tv64 <= new_base->cpu_base->expires_next.tv64;
  #else
  	return 0;
  #endif
  }

  /*
   * Switch the timer base to the current CPU when possible.
   */

  static inline struct hrtimer_clock_base *

  switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
  		    int pinned)

  {

  	struct hrtimer_clock_base *new_base;
  	struct hrtimer_cpu_base *new_cpu_base;

  	int this_cpu = smp_processor_id();
  	int cpu = hrtimer_get_target(this_cpu, pinned);

  again:
  	new_cpu_base = &per_cpu(hrtimer_bases, cpu);

  	new_base = &new_cpu_base->clock_base[base->index];

  
  	if (base != new_base) {
  		/*

  		 * We are trying to move timer to new_base.

  		 * However we can't change timer's base while it is running,
  		 * so we keep it on the same CPU. No hassle vs. reprogramming
  		 * the event source in the high resolution case. The softirq
  		 * code will take care of this when the timer function has
  		 * completed. There is no conflict as we hold the lock until
  		 * the timer is enqueued.
  		 */

  		if (unlikely(hrtimer_callback_running(timer)))

  			return base;
  
  		/* See the comment in lock_timer_base() */
  		timer->base = NULL;

  		raw_spin_unlock(&base->cpu_base->lock);
  		raw_spin_lock(&new_base->cpu_base->lock);

  		if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
  			cpu = this_cpu;

  			raw_spin_unlock(&new_base->cpu_base->lock);
  			raw_spin_lock(&base->cpu_base->lock);

  			timer->base = base;
  			goto again;

  		}

  		timer->base = new_base;
  	}
  	return new_base;
  }
  
  #else /* CONFIG_SMP */

  static inline struct hrtimer_clock_base *

  lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
  {

  	struct hrtimer_clock_base *base = timer->base;

  	raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);

  
  	return base;
  }

  # define switch_hrtimer_base(t, b, p)	(b)

  
  #endif	/* !CONFIG_SMP */
  
  /*
   * Functions for the union type storage format of ktime_t which are
   * too large for inlining:
   */
  #if BITS_PER_LONG < 64
  # ifndef CONFIG_KTIME_SCALAR
  /**
   * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable

   * @kt:		addend
   * @nsec:	the scalar nsec value to add
   *
   * Returns the sum of kt and nsec in ktime_t format
   */
  ktime_t ktime_add_ns(const ktime_t kt, u64 nsec)
  {
  	ktime_t tmp;
  
  	if (likely(nsec < NSEC_PER_SEC)) {
  		tmp.tv64 = nsec;
  	} else {
  		unsigned long rem = do_div(nsec, NSEC_PER_SEC);
  
  		tmp = ktime_set((long)nsec, rem);
  	}
  
  	return ktime_add(kt, tmp);
  }

  
  EXPORT_SYMBOL_GPL(ktime_add_ns);

  
  /**
   * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
   * @kt:		minuend
   * @nsec:	the scalar nsec value to subtract
   *
   * Returns the subtraction of @nsec from @kt in ktime_t format
   */
  ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec)
  {
  	ktime_t tmp;
  
  	if (likely(nsec < NSEC_PER_SEC)) {
  		tmp.tv64 = nsec;
  	} else {
  		unsigned long rem = do_div(nsec, NSEC_PER_SEC);
  
  		tmp = ktime_set((long)nsec, rem);
  	}
  
  	return ktime_sub(kt, tmp);
  }
  
  EXPORT_SYMBOL_GPL(ktime_sub_ns);

  # endif /* !CONFIG_KTIME_SCALAR */
  
  /*
   * Divide a ktime value by a nanosecond value
   */

  u64 ktime_divns(const ktime_t kt, s64 div)

  {

  	u64 dclc;

  	int sft = 0;

  	dclc = ktime_to_ns(kt);

  	/* Make sure the divisor is less than 2^32: */
  	while (div >> 32) {
  		sft++;
  		div >>= 1;
  	}
  	dclc >>= sft;
  	do_div(dclc, (unsigned long) div);

  	return dclc;

  }

  #endif /* BITS_PER_LONG >= 64 */

  /*

   * Add two ktime values and do a safety check for overflow:
   */
  ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
  {
  	ktime_t res = ktime_add(lhs, rhs);
  
  	/*
  	 * We use KTIME_SEC_MAX here, the maximum timeout which we can
  	 * return to user space in a timespec:
  	 */
  	if (res.tv64 < 0 || res.tv64 < lhs.tv64 || res.tv64 < rhs.tv64)
  		res = ktime_set(KTIME_SEC_MAX, 0);
  
  	return res;
  }

  EXPORT_SYMBOL_GPL(ktime_add_safe);

  #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
  
  static struct debug_obj_descr hrtimer_debug_descr;
  
  /*
   * fixup_init is called when:
   * - an active object is initialized
   */
  static int hrtimer_fixup_init(void *addr, enum debug_obj_state state)
  {
  	struct hrtimer *timer = addr;
  
  	switch (state) {
  	case ODEBUG_STATE_ACTIVE:
  		hrtimer_cancel(timer);
  		debug_object_init(timer, &hrtimer_debug_descr);
  		return 1;
  	default:
  		return 0;
  	}
  }
  
  /*
   * fixup_activate is called when:
   * - an active object is activated
   * - an unknown object is activated (might be a statically initialized object)
   */
  static int hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
  {
  	switch (state) {
  
  	case ODEBUG_STATE_NOTAVAILABLE:
  		WARN_ON_ONCE(1);
  		return 0;
  
  	case ODEBUG_STATE_ACTIVE:
  		WARN_ON(1);
  
  	default:
  		return 0;
  	}
  }
  
  /*
   * fixup_free is called when:
   * - an active object is freed
   */
  static int hrtimer_fixup_free(void *addr, enum debug_obj_state state)
  {
  	struct hrtimer *timer = addr;
  
  	switch (state) {
  	case ODEBUG_STATE_ACTIVE:
  		hrtimer_cancel(timer);
  		debug_object_free(timer, &hrtimer_debug_descr);
  		return 1;
  	default:
  		return 0;
  	}
  }
  
  static struct debug_obj_descr hrtimer_debug_descr = {
  	.name		= "hrtimer",
  	.fixup_init	= hrtimer_fixup_init,
  	.fixup_activate	= hrtimer_fixup_activate,
  	.fixup_free	= hrtimer_fixup_free,
  };
  
  static inline void debug_hrtimer_init(struct hrtimer *timer)
  {
  	debug_object_init(timer, &hrtimer_debug_descr);
  }
  
  static inline void debug_hrtimer_activate(struct hrtimer *timer)
  {
  	debug_object_activate(timer, &hrtimer_debug_descr);
  }
  
  static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
  {
  	debug_object_deactivate(timer, &hrtimer_debug_descr);
  }
  
  static inline void debug_hrtimer_free(struct hrtimer *timer)
  {
  	debug_object_free(timer, &hrtimer_debug_descr);
  }
  
  static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
  			   enum hrtimer_mode mode);
  
  void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
  			   enum hrtimer_mode mode)
  {
  	debug_object_init_on_stack(timer, &hrtimer_debug_descr);
  	__hrtimer_init(timer, clock_id, mode);
  }

  EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);

  
  void destroy_hrtimer_on_stack(struct hrtimer *timer)
  {
  	debug_object_free(timer, &hrtimer_debug_descr);
  }
  
  #else
  static inline void debug_hrtimer_init(struct hrtimer *timer) { }
  static inline void debug_hrtimer_activate(struct hrtimer *timer) { }
  static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
  #endif

  static inline void
  debug_init(struct hrtimer *timer, clockid_t clockid,
  	   enum hrtimer_mode mode)
  {
  	debug_hrtimer_init(timer);
  	trace_hrtimer_init(timer, clockid, mode);
  }
  
  static inline void debug_activate(struct hrtimer *timer)
  {
  	debug_hrtimer_activate(timer);
  	trace_hrtimer_start(timer);
  }
  
  static inline void debug_deactivate(struct hrtimer *timer)
  {
  	debug_hrtimer_deactivate(timer);
  	trace_hrtimer_cancel(timer);
  }

  /* High resolution timer related functions */
  #ifdef CONFIG_HIGH_RES_TIMERS
  
  /*
   * High resolution timer enabled ?
   */
  static int hrtimer_hres_enabled __read_mostly  = 1;
  
  /*
   * Enable / Disable high resolution mode
   */
  static int __init setup_hrtimer_hres(char *str)
  {
  	if (!strcmp(str, "off"))
  		hrtimer_hres_enabled = 0;
  	else if (!strcmp(str, "on"))
  		hrtimer_hres_enabled = 1;
  	else
  		return 0;
  	return 1;
  }
  
  __setup("highres=", setup_hrtimer_hres);
  
  /*
   * hrtimer_high_res_enabled - query, if the highres mode is enabled
   */
  static inline int hrtimer_is_hres_enabled(void)
  {
  	return hrtimer_hres_enabled;
  }
  
  /*
   * Is the high resolution mode active ?
   */
  static inline int hrtimer_hres_active(void)
  {
  	return __get_cpu_var(hrtimer_bases).hres_active;
  }
  
  /*
   * Reprogram the event source with checking both queues for the
   * next event
   * Called with interrupts disabled and base->lock held
   */

  static void
  hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)

  {
  	int i;
  	struct hrtimer_clock_base *base = cpu_base->clock_base;

  	ktime_t expires, expires_next;

  	expires_next.tv64 = KTIME_MAX;

  
  	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
  		struct hrtimer *timer;
  
  		if (!base->first)
  			continue;
  		timer = rb_entry(base->first, struct hrtimer, node);

  		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);

  		/*
  		 * clock_was_set() has changed base->offset so the
  		 * result might be negative. Fix it up to prevent a
  		 * false positive in clockevents_program_event()
  		 */
  		if (expires.tv64 < 0)
  			expires.tv64 = 0;

  		if (expires.tv64 < expires_next.tv64)
  			expires_next = expires;

  	}

  	if (skip_equal && expires_next.tv64 == cpu_base->expires_next.tv64)
  		return;
  
  	cpu_base->expires_next.tv64 = expires_next.tv64;

  	if (cpu_base->expires_next.tv64 != KTIME_MAX)
  		tick_program_event(cpu_base->expires_next, 1);
  }
  
  /*
   * Shared reprogramming for clock_realtime and clock_monotonic
   *
   * When a timer is enqueued and expires earlier than the already enqueued
   * timers, we have to check, whether it expires earlier than the timer for
   * which the clock event device was armed.
   *
   * Called with interrupts disabled and base->cpu_base.lock held
   */
  static int hrtimer_reprogram(struct hrtimer *timer,
  			     struct hrtimer_clock_base *base)
  {

  	struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);

  	ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);

  	int res;

  	WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);

  	/*
  	 * When the callback is running, we do not reprogram the clock event
  	 * device. The timer callback is either running on a different CPU or

  	 * the callback is executed in the hrtimer_interrupt context. The

  	 * reprogramming is handled either by the softirq, which called the
  	 * callback or at the end of the hrtimer_interrupt.
  	 */
  	if (hrtimer_callback_running(timer))
  		return 0;

  	/*
  	 * CLOCK_REALTIME timer might be requested with an absolute
  	 * expiry time which is less than base->offset. Nothing wrong
  	 * about that, just avoid to call into the tick code, which
  	 * has now objections against negative expiry values.
  	 */
  	if (expires.tv64 < 0)
  		return -ETIME;

  	if (expires.tv64 >= cpu_base->expires_next.tv64)
  		return 0;
  
  	/*
  	 * If a hang was detected in the last timer interrupt then we
  	 * do not schedule a timer which is earlier than the expiry
  	 * which we enforced in the hang detection. We want the system
  	 * to make progress.
  	 */
  	if (cpu_base->hang_detected)

  		return 0;
  
  	/*
  	 * Clockevents returns -ETIME, when the event was in the past.
  	 */
  	res = tick_program_event(expires, 0);
  	if (!IS_ERR_VALUE(res))

  		cpu_base->expires_next = expires;

  	return res;
  }
  
  
  /*
   * Retrigger next event is called after clock was set
   *
   * Called with interrupts disabled via on_each_cpu()
   */
  static void retrigger_next_event(void *arg)
  {
  	struct hrtimer_cpu_base *base;
  	struct timespec realtime_offset;
  	unsigned long seq;
  
  	if (!hrtimer_hres_active())
  		return;
  
  	do {
  		seq = read_seqbegin(&xtime_lock);
  		set_normalized_timespec(&realtime_offset,
  					-wall_to_monotonic.tv_sec,
  					-wall_to_monotonic.tv_nsec);
  	} while (read_seqretry(&xtime_lock, seq));
  
  	base = &__get_cpu_var(hrtimer_bases);
  
  	/* Adjust CLOCK_REALTIME offset */

  	raw_spin_lock(&base->lock);

  	base->clock_base[CLOCK_REALTIME].offset =
  		timespec_to_ktime(realtime_offset);

  	hrtimer_force_reprogram(base, 0);

  	raw_spin_unlock(&base->lock);

  }
  
  /*
   * Clock realtime was set
   *
   * Change the offset of the realtime clock vs. the monotonic
   * clock.
   *
   * We might have to reprogram the high resolution timer interrupt. On
   * SMP we call the architecture specific code to retrigger _all_ high
   * resolution timer interrupts. On UP we just disable interrupts and
   * call the high resolution interrupt code.
   */
  void clock_was_set(void)
  {
  	/* Retrigger the CPU local events everywhere */

  	on_each_cpu(retrigger_next_event, NULL, 1);

  }
  
  /*

   * During resume we might have to reprogram the high resolution timer
   * interrupt (on the local CPU):
   */
  void hres_timers_resume(void)
  {

  	WARN_ONCE(!irqs_disabled(),
  		  KERN_INFO "hres_timers_resume() called with IRQs enabled!");

  	retrigger_next_event(NULL);
  }
  
  /*

   * Initialize the high resolution related parts of cpu_base
   */
  static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
  {
  	base->expires_next.tv64 = KTIME_MAX;
  	base->hres_active = 0;

  }
  
  /*
   * Initialize the high resolution related parts of a hrtimer
   */
  static inline void hrtimer_init_timer_hres(struct hrtimer *timer)
  {

  }

  /*
   * When High resolution timers are active, try to reprogram. Note, that in case
   * the state has HRTIMER_STATE_CALLBACK set, no reprogramming and no expiry
   * check happens. The timer gets enqueued into the rbtree. The reprogramming
   * and expiry check is done in the hrtimer_interrupt or in the softirq.
   */
  static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,

  					    struct hrtimer_clock_base *base,
  					    int wakeup)

  {
  	if (base->cpu_base->hres_active && hrtimer_reprogram(timer, base)) {

  		if (wakeup) {

  			raw_spin_unlock(&base->cpu_base->lock);

  			raise_softirq_irqoff(HRTIMER_SOFTIRQ);

  			raw_spin_lock(&base->cpu_base->lock);

  		} else
  			__raise_softirq_irqoff(HRTIMER_SOFTIRQ);

  		return 1;

  	}

  	return 0;
  }
  
  /*
   * Switch to high resolution mode
   */

  static int hrtimer_switch_to_hres(void)

  {

  	int cpu = smp_processor_id();
  	struct hrtimer_cpu_base *base = &per_cpu(hrtimer_bases, cpu);

  	unsigned long flags;
  
  	if (base->hres_active)

  		return 1;

  
  	local_irq_save(flags);
  
  	if (tick_init_highres()) {
  		local_irq_restore(flags);

  		printk(KERN_WARNING "Could not switch to high resolution "
  				    "mode on CPU %d
  ", cpu);

  		return 0;

  	}
  	base->hres_active = 1;
  	base->clock_base[CLOCK_REALTIME].resolution = KTIME_HIGH_RES;
  	base->clock_base[CLOCK_MONOTONIC].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;

  }
  
  #else
  
  static inline int hrtimer_hres_active(void) { return 0; }
  static inline int hrtimer_is_hres_enabled(void) { return 0; }

  static inline int hrtimer_switch_to_hres(void) { return 0; }

  static inline void
  hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }

  static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,

  					    struct hrtimer_clock_base *base,
  					    int wakeup)

  {
  	return 0;
  }

  static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
  static inline void hrtimer_init_timer_hres(struct hrtimer *timer) { }
  
  #endif /* CONFIG_HIGH_RES_TIMERS */

  static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)

  {

  #ifdef CONFIG_TIMER_STATS

  	if (timer->start_site)
  		return;

  	timer->start_site = __builtin_return_address(0);

  	memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
  	timer->start_pid = current->pid;

  #endif
  }
  
  static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
  {
  #ifdef CONFIG_TIMER_STATS
  	timer->start_site = NULL;
  #endif

  }

  
  static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
  {
  #ifdef CONFIG_TIMER_STATS
  	if (likely(!timer_stats_active))
  		return;
  	timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
  				 timer->function, timer->start_comm, 0);

  #endif

  }

  /*

   * Counterpart to lock_hrtimer_base above:

   */
  static inline
  void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
  {

  	raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);

  }
  
  /**
   * hrtimer_forward - forward the timer expiry

   * @timer:	hrtimer to forward

   * @now:	forward past this time

   * @interval:	the interval to forward
   *
   * Forward the timer expiry so it will expire in the future.

   * Returns the number of overruns.

   */

  u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)

  {

  	u64 orun = 1;

  	ktime_t delta;

  	delta = ktime_sub(now, hrtimer_get_expires(timer));

  
  	if (delta.tv64 < 0)
  		return 0;

  	if (interval.tv64 < timer->base->resolution.tv64)
  		interval.tv64 = timer->base->resolution.tv64;

  	if (unlikely(delta.tv64 >= interval.tv64)) {

  		s64 incr = ktime_to_ns(interval);

  
  		orun = ktime_divns(delta, incr);

  		hrtimer_add_expires_ns(timer, incr * orun);
  		if (hrtimer_get_expires_tv64(timer) > now.tv64)

  			return orun;
  		/*
  		 * This (and the ktime_add() below) is the
  		 * correction for exact:
  		 */
  		orun++;
  	}

  	hrtimer_add_expires(timer, interval);

  
  	return orun;
  }

  EXPORT_SYMBOL_GPL(hrtimer_forward);

  
  /*
   * enqueue_hrtimer - internal function to (re)start a timer
   *
   * The timer is inserted in expiry order. Insertion into the
   * red black tree is O(log(n)). Must hold the base lock.

   *
   * Returns 1 when the new timer is the leftmost timer in the tree.

   */

  static int enqueue_hrtimer(struct hrtimer *timer,
  			   struct hrtimer_clock_base *base)

  {
  	struct rb_node **link = &base->active.rb_node;

  	struct rb_node *parent = NULL;
  	struct hrtimer *entry;

  	int leftmost = 1;

  	debug_activate(timer);

  	/*
  	 * Find the right place in the rbtree:
  	 */
  	while (*link) {
  		parent = *link;
  		entry = rb_entry(parent, struct hrtimer, node);
  		/*
  		 * We dont care about collisions. Nodes with
  		 * the same expiry time stay together.
  		 */

  		if (hrtimer_get_expires_tv64(timer) <
  				hrtimer_get_expires_tv64(entry)) {

  			link = &(*link)->rb_left;

  		} else {

  			link = &(*link)->rb_right;

  			leftmost = 0;
  		}

  	}
  
  	/*

  	 * Insert the timer to the rbtree and check whether it
  	 * replaces the first pending timer

  	 */

  	if (leftmost)

  		base->first = &timer->node;

  	rb_link_node(&timer->node, parent, link);
  	rb_insert_color(&timer->node, &base->active);

  	/*
  	 * HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the
  	 * state of a possibly running callback.
  	 */
  	timer->state |= HRTIMER_STATE_ENQUEUED;

  
  	return leftmost;

  }

  
  /*
   * __remove_hrtimer - internal function to remove a timer
   *
   * Caller must hold the base lock.

   *
   * High resolution timer mode reprograms the clock event device when the
   * timer is the one which expires next. The caller can disable this by setting
   * reprogram to zero. This is useful, when the context does a reprogramming
   * anyway (e.g. timer interrupt)

   */

  static void __remove_hrtimer(struct hrtimer *timer,

  			     struct hrtimer_clock_base *base,

  			     unsigned long newstate, int reprogram)

  {

  	if (!(timer->state & HRTIMER_STATE_ENQUEUED))
  		goto out;
  
  	/*
  	 * Remove the timer from the rbtree and replace the first
  	 * entry pointer if necessary.
  	 */
  	if (base->first == &timer->node) {
  		base->first = rb_next(&timer->node);
  #ifdef CONFIG_HIGH_RES_TIMERS
  		/* Reprogram the clock event device. if enabled */
  		if (reprogram && hrtimer_hres_active()) {
  			ktime_t expires;
  
  			expires = ktime_sub(hrtimer_get_expires(timer),
  					    base->offset);
  			if (base->cpu_base->expires_next.tv64 == expires.tv64)
  				hrtimer_force_reprogram(base->cpu_base, 1);

  		}

  #endif

  	}

  	rb_erase(&timer->node, &base->active);
  out:

  	timer->state = newstate;

  }
  
  /*
   * remove hrtimer, called with base lock held
   */
  static inline int

  remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)

  {

  	if (hrtimer_is_queued(timer)) {

  		int reprogram;
  
  		/*
  		 * Remove the timer and force reprogramming when high
  		 * resolution mode is active and the timer is on the current
  		 * CPU. If we remove a timer on another CPU, reprogramming is
  		 * skipped. The interrupt event on this CPU is fired and
  		 * reprogramming happens in the interrupt handler. This is a
  		 * rare case and less expensive than a smp call.
  		 */

  		debug_deactivate(timer);

  		timer_stats_hrtimer_clear_start_info(timer);

  		reprogram = base->cpu_base == &__get_cpu_var(hrtimer_bases);
  		__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE,
  				 reprogram);

  		return 1;
  	}
  	return 0;
  }

  int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
  		unsigned long delta_ns, const enum hrtimer_mode mode,
  		int wakeup)

  {

  	struct hrtimer_clock_base *base, *new_base;

  	unsigned long flags;

  	int ret, leftmost;

  
  	base = lock_hrtimer_base(timer, &flags);
  
  	/* Remove an active timer from the queue: */
  	ret = remove_hrtimer(timer, base);
  
  	/* Switch the timer base, if necessary: */

  	new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);

  	if (mode & HRTIMER_MODE_REL) {

  		tim = ktime_add_safe(tim, new_base->get_time());

  		/*
  		 * CONFIG_TIME_LOW_RES is a temporary way for architectures
  		 * to signal that they simply return xtime in
  		 * do_gettimeoffset(). In this case we want to round up by
  		 * resolution when starting a relative timer, to avoid short
  		 * timeouts. This will go away with the GTOD framework.
  		 */
  #ifdef CONFIG_TIME_LOW_RES

  		tim = ktime_add_safe(tim, base->resolution);

  #endif
  	}

  	hrtimer_set_expires_range_ns(timer, tim, delta_ns);

  	timer_stats_hrtimer_set_start_info(timer);

  	leftmost = enqueue_hrtimer(timer, new_base);

  	/*
  	 * Only allow reprogramming if the new base is on this CPU.
  	 * (it might still be on another CPU if the timer was pending)

  	 *
  	 * XXX send_remote_softirq() ?

  	 */

  	if (leftmost && new_base->cpu_base == &__get_cpu_var(hrtimer_bases))

  		hrtimer_enqueue_reprogram(timer, new_base, wakeup);

  
  	unlock_hrtimer_base(timer, &flags);
  
  	return ret;
  }

  
  /**
   * hrtimer_start_range_ns - (re)start an hrtimer on the current CPU
   * @timer:	the timer to be added
   * @tim:	expiry time
   * @delta_ns:	"slack" range for the timer
   * @mode:	expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
   *
   * Returns:
   *  0 on success
   *  1 when the timer was active
   */
  int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
  		unsigned long delta_ns, const enum hrtimer_mode mode)
  {
  	return __hrtimer_start_range_ns(timer, tim, delta_ns, mode, 1);
  }

  EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
  
  /**

   * hrtimer_start - (re)start an hrtimer on the current CPU

   * @timer:	the timer to be added
   * @tim:	expiry time
   * @mode:	expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
   *
   * Returns:
   *  0 on success
   *  1 when the timer was active
   */
  int
  hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
  {

  	return __hrtimer_start_range_ns(timer, tim, 0, mode, 1);

  }

  EXPORT_SYMBOL_GPL(hrtimer_start);

  /**
   * hrtimer_try_to_cancel - try to deactivate a timer

   * @timer:	hrtimer to stop
   *
   * Returns:
   *  0 when the timer was not active
   *  1 when the timer was active
   * -1 when the timer is currently excuting the callback function and

   *    cannot be stopped

   */
  int hrtimer_try_to_cancel(struct hrtimer *timer)
  {

  	struct hrtimer_clock_base *base;

  	unsigned long flags;
  	int ret = -1;
  
  	base = lock_hrtimer_base(timer, &flags);

  	if (!hrtimer_callback_running(timer))

  		ret = remove_hrtimer(timer, base);
  
  	unlock_hrtimer_base(timer, &flags);
  
  	return ret;
  
  }

  EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);

  
  /**
   * hrtimer_cancel - cancel a timer and wait for the handler to finish.

   * @timer:	the timer to be cancelled
   *
   * Returns:
   *  0 when the timer was not active
   *  1 when the timer was active
   */
  int hrtimer_cancel(struct hrtimer *timer)
  {
  	for (;;) {
  		int ret = hrtimer_try_to_cancel(timer);
  
  		if (ret >= 0)
  			return ret;

  		cpu_relax();

  	}
  }

  EXPORT_SYMBOL_GPL(hrtimer_cancel);

  
  /**
   * hrtimer_get_remaining - get remaining time for the timer

   * @timer:	the timer to read
   */
  ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
  {

  	struct hrtimer_clock_base *base;

  	unsigned long flags;
  	ktime_t rem;
  
  	base = lock_hrtimer_base(timer, &flags);

  	rem = hrtimer_expires_remaining(timer);

  	unlock_hrtimer_base(timer, &flags);
  
  	return rem;
  }

  EXPORT_SYMBOL_GPL(hrtimer_get_remaining);

  #ifdef CONFIG_NO_HZ

  /**
   * hrtimer_get_next_event - get the time until next expiry event
   *
   * Returns the delta to the next expiry event or KTIME_MAX if no timer
   * is pending.
   */
  ktime_t hrtimer_get_next_event(void)
  {

  	struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
  	struct hrtimer_clock_base *base = cpu_base->clock_base;

  	ktime_t delta, mindelta = { .tv64 = KTIME_MAX };
  	unsigned long flags;
  	int i;

  	raw_spin_lock_irqsave(&cpu_base->lock, flags);

  	if (!hrtimer_hres_active()) {
  		for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
  			struct hrtimer *timer;

  			if (!base->first)
  				continue;

  			timer = rb_entry(base->first, struct hrtimer, node);

  			delta.tv64 = hrtimer_get_expires_tv64(timer);

  			delta = ktime_sub(delta, base->get_time());
  			if (delta.tv64 < mindelta.tv64)
  				mindelta.tv64 = delta.tv64;
  		}

  	}

  	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);

  	if (mindelta.tv64 < 0)
  		mindelta.tv64 = 0;
  	return mindelta;
  }
  #endif

  static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
  			   enum hrtimer_mode mode)

  {

  	struct hrtimer_cpu_base *cpu_base;

  	memset(timer, 0, sizeof(struct hrtimer));

  	cpu_base = &__raw_get_cpu_var(hrtimer_bases);

  	if (clock_id == CLOCK_REALTIME && mode != HRTIMER_MODE_ABS)

  		clock_id = CLOCK_MONOTONIC;

  	timer->base = &cpu_base->clock_base[clock_id];

  	hrtimer_init_timer_hres(timer);

  
  #ifdef CONFIG_TIMER_STATS
  	timer->start_site = NULL;
  	timer->start_pid = -1;
  	memset(timer->start_comm, 0, TASK_COMM_LEN);
  #endif

  }

  
  /**
   * hrtimer_init - initialize a timer to the given clock
   * @timer:	the timer to be initialized
   * @clock_id:	the clock to be used
   * @mode:	timer mode abs/rel
   */
  void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
  		  enum hrtimer_mode mode)
  {

  	debug_init(timer, clock_id, mode);

  	__hrtimer_init(timer, clock_id, mode);
  }

  EXPORT_SYMBOL_GPL(hrtimer_init);

  
  /**
   * hrtimer_get_res - get the timer resolution for a clock

   * @which_clock: which clock to query
   * @tp:		 pointer to timespec variable to store the resolution
   *

   * Store the resolution of the clock selected by @which_clock in the
   * variable pointed to by @tp.

   */
  int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
  {

  	struct hrtimer_cpu_base *cpu_base;

  	cpu_base = &__raw_get_cpu_var(hrtimer_bases);
  	*tp = ktime_to_timespec(cpu_base->clock_base[which_clock].resolution);

  
  	return 0;
  }

  EXPORT_SYMBOL_GPL(hrtimer_get_res);

  static void __run_hrtimer(struct hrtimer *timer, ktime_t *now)

  {
  	struct hrtimer_clock_base *base = timer->base;
  	struct hrtimer_cpu_base *cpu_base = base->cpu_base;
  	enum hrtimer_restart (*fn)(struct hrtimer *);
  	int restart;

  	WARN_ON(!irqs_disabled());

  	debug_deactivate(timer);

  	__remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0);
  	timer_stats_account_hrtimer(timer);

  	fn = timer->function;

  
  	/*
  	 * Because we run timers from hardirq context, there is no chance
  	 * they get migrated to another cpu, therefore its safe to unlock
  	 * the timer base.
  	 */

  	raw_spin_unlock(&cpu_base->lock);

  	trace_hrtimer_expire_entry(timer, now);

  	restart = fn(timer);

  	trace_hrtimer_expire_exit(timer);

  	raw_spin_lock(&cpu_base->lock);

  
  	/*

  	 * Note: We clear the CALLBACK bit after enqueue_hrtimer and
  	 * we do not reprogramm the event hardware. Happens either in
  	 * hrtimer_start_range_ns() or in hrtimer_interrupt()

  	 */
  	if (restart != HRTIMER_NORESTART) {
  		BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);

  		enqueue_hrtimer(timer, base);

  	}
  	timer->state &= ~HRTIMER_STATE_CALLBACK;
  }

  #ifdef CONFIG_HIGH_RES_TIMERS
  
  /*
   * High resolution timer interrupt
   * Called with interrupts disabled
   */
  void hrtimer_interrupt(struct clock_event_device *dev)
  {
  	struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
  	struct hrtimer_clock_base *base;

  	ktime_t expires_next, now, entry_time, delta;
  	int i, retries = 0;

  
  	BUG_ON(!cpu_base->hres_active);
  	cpu_base->nr_events++;
  	dev->next_event.tv64 = KTIME_MAX;

  	entry_time = now = ktime_get();
  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
  	 * the migration code. This does not affect enqueueing of
  	 * timers which run their callback and need to be requeued on
  	 * this CPU.
  	 */
  	cpu_base->expires_next.tv64 = KTIME_MAX;

  	base = cpu_base->clock_base;
  
  	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
  		ktime_t basenow;
  		struct rb_node *node;

  		basenow = ktime_add(now, base->offset);
  
  		while ((node = base->first)) {
  			struct hrtimer *timer;
  
  			timer = rb_entry(node, struct hrtimer, node);

  			/*
  			 * The immediate goal for using the softexpires is
  			 * minimizing wakeups, not running timers at the
  			 * earliest interrupt after their soft expiration.
  			 * This allows us to avoid using a Priority Search
  			 * Tree, which can answer a stabbing querry for
  			 * overlapping intervals and instead use the simple
  			 * BST we already have.
  			 * We don't add extra wakeups by delaying timers that
  			 * are right-of a not yet expired timer, because that
  			 * timer will have to trigger a wakeup anyway.
  			 */
  
  			if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer)) {

  				ktime_t expires;

  				expires = ktime_sub(hrtimer_get_expires(timer),

  						    base->offset);
  				if (expires.tv64 < expires_next.tv64)
  					expires_next = expires;
  				break;
  			}

  			__run_hrtimer(timer, &basenow);

  		}

  		base++;
  	}

  	/*
  	 * Store the new expiry value so the migration code can verify
  	 * against it.
  	 */

  	cpu_base->expires_next = expires_next;

  	raw_spin_unlock(&cpu_base->lock);

  
  	/* Reprogramming necessary ? */

  	if (expires_next.tv64 == KTIME_MAX ||
  	    !tick_program_event(expires_next, 0)) {
  		cpu_base->hang_detected = 0;
  		return;

  	}

  
  	/*
  	 * The next timer was already expired due to:
  	 * - tracing
  	 * - long lasting callbacks
  	 * - being scheduled away when running in a VM
  	 *
  	 * 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.
  	 */
  	now = ktime_get();
  	cpu_base->nr_retries++;
  	if (++retries < 3)
  		goto retry;
  	/*
  	 * Give the system a chance to do something else than looping
  	 * here. We stored the entry time, so we know exactly how long
  	 * we spent here. We schedule the next event this amount of
  	 * time away.
  	 */
  	cpu_base->nr_hangs++;
  	cpu_base->hang_detected = 1;
  	delta = ktime_sub(now, entry_time);
  	if (delta.tv64 > cpu_base->max_hang_time.tv64)
  		cpu_base->max_hang_time = delta;
  	/*
  	 * Limit it to a sensible value as we enforce a longer
  	 * delay. Give the CPU at least 100ms to catch up.
  	 */
  	if (delta.tv64 > 100 * NSEC_PER_MSEC)
  		expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
  	else
  		expires_next = ktime_add(now, delta);
  	tick_program_event(expires_next, 1);
  	printk_once(KERN_WARNING "hrtimer: interrupt took %llu ns
  ",
  		    ktime_to_ns(delta));

  }

  /*
   * local version of hrtimer_peek_ahead_timers() called with interrupts
   * disabled.
   */
  static void __hrtimer_peek_ahead_timers(void)
  {
  	struct tick_device *td;
  
  	if (!hrtimer_hres_active())
  		return;
  
  	td = &__get_cpu_var(tick_cpu_device);
  	if (td && td->evtdev)
  		hrtimer_interrupt(td->evtdev);
  }

  /**
   * hrtimer_peek_ahead_timers -- run soft-expired timers now
   *
   * hrtimer_peek_ahead_timers will peek at the timer queue of
   * the current cpu and check if there are any timers for which
   * the soft expires time has passed. If any such timers exist,
   * they are run immediately and then removed from the timer queue.
   *
   */
  void hrtimer_peek_ahead_timers(void)
  {

  	unsigned long flags;

  	local_irq_save(flags);

  	__hrtimer_peek_ahead_timers();

  	local_irq_restore(flags);
  }

  static void run_hrtimer_softirq(struct softirq_action *h)
  {
  	hrtimer_peek_ahead_timers();
  }

  #else /* CONFIG_HIGH_RES_TIMERS */
  
  static inline void __hrtimer_peek_ahead_timers(void) { }
  
  #endif	/* !CONFIG_HIGH_RES_TIMERS */

  /*
   * Called from timer softirq every jiffy, expire hrtimers:
   *
   * For HRT its the fall back code to run the softirq in the timer
   * softirq context in case the hrtimer initialization failed or has
   * not been done yet.
   */
  void hrtimer_run_pending(void)
  {

  	if (hrtimer_hres_active())
  		return;

  	/*
  	 * This _is_ ugly: We have to check in the softirq context,
  	 * whether we can switch to highres and / or nohz mode. The
  	 * clocksource switch happens in the timer interrupt with
  	 * xtime_lock held. Notification from there only sets the
  	 * check bit in the tick_oneshot code, otherwise we might
  	 * deadlock vs. xtime_lock.
  	 */
  	if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
  		hrtimer_switch_to_hres();

  }

  /*

   * Called from hardirq context every jiffy

   */

  void hrtimer_run_queues(void)

  {

  	struct rb_node *node;

  	struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
  	struct hrtimer_clock_base *base;
  	int index, gettime = 1;

  	if (hrtimer_hres_active())

  		return;

  	for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {
  		base = &cpu_base->clock_base[index];

  		if (!base->first)

  			continue;

  		if (gettime) {

  			hrtimer_get_softirq_time(cpu_base);
  			gettime = 0;

  		}

  		raw_spin_lock(&cpu_base->lock);

  		while ((node = base->first)) {
  			struct hrtimer *timer;

  			timer = rb_entry(node, struct hrtimer, node);

  			if (base->softirq_time.tv64 <=
  					hrtimer_get_expires_tv64(timer))

  				break;

  			__run_hrtimer(timer, &base->softirq_time);

  		}

  		raw_spin_unlock(&cpu_base->lock);

  	}

  }
  
  /*

   * Sleep related functions:
   */

  static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)

  {
  	struct hrtimer_sleeper *t =
  		container_of(timer, struct hrtimer_sleeper, timer);
  	struct task_struct *task = t->task;
  
  	t->task = NULL;
  	if (task)
  		wake_up_process(task);
  
  	return HRTIMER_NORESTART;
  }

  void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task)

  {
  	sl->timer.function = hrtimer_wakeup;
  	sl->task = task;
  }

  EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);

  static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)

  {

  	hrtimer_init_sleeper(t, current);

  	do {
  		set_current_state(TASK_INTERRUPTIBLE);

  		hrtimer_start_expires(&t->timer, mode);

  		if (!hrtimer_active(&t->timer))
  			t->task = NULL;

  		if (likely(t->task))
  			schedule();

  		hrtimer_cancel(&t->timer);

  		mode = HRTIMER_MODE_ABS;

  
  	} while (t->task && !signal_pending(current));

  	__set_current_state(TASK_RUNNING);

  	return t->task == NULL;

  }

  static int update_rmtp(struct hrtimer *timer, struct timespec __user *rmtp)
  {
  	struct timespec rmt;
  	ktime_t rem;

  	rem = hrtimer_expires_remaining(timer);

  	if (rem.tv64 <= 0)
  		return 0;
  	rmt = ktime_to_timespec(rem);
  
  	if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
  		return -EFAULT;
  
  	return 1;
  }

  long __sched hrtimer_nanosleep_restart(struct restart_block *restart)

  {

  	struct hrtimer_sleeper t;

  	struct timespec __user  *rmtp;

  	int ret = 0;

  	hrtimer_init_on_stack(&t.timer, restart->nanosleep.index,
  				HRTIMER_MODE_ABS);

  	hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);

  	if (do_nanosleep(&t, HRTIMER_MODE_ABS))

  		goto out;

  	rmtp = restart->nanosleep.rmtp;

  	if (rmtp) {

  		ret = update_rmtp(&t.timer, rmtp);

  		if (ret <= 0)

  			goto out;

  	}

  	/* The other values in restart are already filled in */

  	ret = -ERESTART_RESTARTBLOCK;
  out:
  	destroy_hrtimer_on_stack(&t.timer);
  	return ret;

  }

  long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,

  		       const enum hrtimer_mode mode, const clockid_t clockid)
  {
  	struct restart_block *restart;

  	struct hrtimer_sleeper t;

  	int ret = 0;

  	unsigned long slack;
  
  	slack = current->timer_slack_ns;
  	if (rt_task(current))
  		slack = 0;

  	hrtimer_init_on_stack(&t.timer, clockid, mode);

  	hrtimer_set_expires_range_ns(&t.timer, timespec_to_ktime(*rqtp), slack);

  	if (do_nanosleep(&t, mode))

  		goto out;

  	/* Absolute timers do not update the rmtp value and restart: */

  	if (mode == HRTIMER_MODE_ABS) {
  		ret = -ERESTARTNOHAND;
  		goto out;
  	}

  	if (rmtp) {

  		ret = update_rmtp(&t.timer, rmtp);

  		if (ret <= 0)

  			goto out;

  	}

  
  	restart = &current_thread_info()->restart_block;

  	restart->fn = hrtimer_nanosleep_restart;

  	restart->nanosleep.index = t.timer.base->index;
  	restart->nanosleep.rmtp = rmtp;

  	restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);

  	ret = -ERESTART_RESTARTBLOCK;
  out:
  	destroy_hrtimer_on_stack(&t.timer);
  	return ret;

  }

  SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
  		struct timespec __user *, rmtp)

  {

  	struct timespec tu;

  
  	if (copy_from_user(&tu, rqtp, sizeof(tu)))
  		return -EFAULT;
  
  	if (!timespec_valid(&tu))
  		return -EINVAL;

  	return hrtimer_nanosleep(&tu, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC);

  }

  /*

   * Functions related to boot-time initialization:
   */

  static void __cpuinit init_hrtimers_cpu(int cpu)

  {

  	struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);

  	int i;

  	raw_spin_lock_init(&cpu_base->lock);

  
  	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)
  		cpu_base->clock_base[i].cpu_base = cpu_base;

  	hrtimer_init_hres(cpu_base);

  }
  
  #ifdef CONFIG_HOTPLUG_CPU

  static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,

  				struct hrtimer_clock_base *new_base)

  {
  	struct hrtimer *timer;
  	struct rb_node *node;
  
  	while ((node = rb_first(&old_base->active))) {
  		timer = rb_entry(node, struct hrtimer, node);

  		BUG_ON(hrtimer_callback_running(timer));

  		debug_deactivate(timer);

  
  		/*
  		 * Mark it as STATE_MIGRATE not INACTIVE otherwise the
  		 * timer could be seen as !active and just vanish away
  		 * under us on another CPU
  		 */
  		__remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0);

  		timer->base = new_base;

  		/*

  		 * Enqueue the timers on the new cpu. This does not
  		 * reprogram the event device in case the timer
  		 * expires before the earliest on this CPU, but we run
  		 * hrtimer_interrupt after we migrated everything to
  		 * sort out already expired timers and reprogram the
  		 * event device.

  		 */

  		enqueue_hrtimer(timer, new_base);

  		/* Clear the migration state bit */
  		timer->state &= ~HRTIMER_STATE_MIGRATE;

  	}
  }

  static void migrate_hrtimers(int scpu)

  {

  	struct hrtimer_cpu_base *old_base, *new_base;

  	int i;

  	BUG_ON(cpu_online(scpu));

  	tick_cancel_sched_timer(scpu);

  
  	local_irq_disable();
  	old_base = &per_cpu(hrtimer_bases, scpu);
  	new_base = &__get_cpu_var(hrtimer_bases);

  	/*
  	 * The caller is globally serialized and nobody else
  	 * takes two locks at once, deadlock is not possible.
  	 */

  	raw_spin_lock(&new_base->lock);
  	raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);

  	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {

  		migrate_hrtimer_list(&old_base->clock_base[i],

  				     &new_base->clock_base[i]);

  	}

  	raw_spin_unlock(&old_base->lock);
  	raw_spin_unlock(&new_base->lock);

  	/* Check, if we got expired work to do */
  	__hrtimer_peek_ahead_timers();
  	local_irq_enable();

  }

  #endif /* CONFIG_HOTPLUG_CPU */

  static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self,

  					unsigned long action, void *hcpu)
  {

  	int scpu = (long)hcpu;

  
  	switch (action) {
  
  	case CPU_UP_PREPARE:

  	case CPU_UP_PREPARE_FROZEN:

  		init_hrtimers_cpu(scpu);

  		break;
  
  #ifdef CONFIG_HOTPLUG_CPU

  	case CPU_DYING:
  	case CPU_DYING_FROZEN:
  		clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DYING, &scpu);
  		break;

  	case CPU_DEAD:

  	case CPU_DEAD_FROZEN:

  	{

  		clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu);

  		migrate_hrtimers(scpu);

  		break;

  	}

  #endif
  
  	default:
  		break;
  	}
  
  	return NOTIFY_OK;
  }

  static struct notifier_block __cpuinitdata hrtimers_nb = {

  	.notifier_call = hrtimer_cpu_notify,
  };
  
  void __init hrtimers_init(void)
  {
  	hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
  			  (void *)(long)smp_processor_id());
  	register_cpu_notifier(&hrtimers_nb);

  #ifdef CONFIG_HIGH_RES_TIMERS
  	open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq);
  #endif

  }

  /**

   * schedule_hrtimeout_range - sleep until timeout

   * @expires:	timeout value (ktime_t)

   * @delta:	slack in expires timeout (ktime_t)

   * @mode:	timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
   *
   * Make the current task sleep until the given expiry time has
   * elapsed. The routine will return immediately unless
   * the current task state has been set (see set_current_state()).
   *

   * The @delta argument gives the kernel the freedom to schedule the
   * actual wakeup to a time that is both power and performance friendly.
   * The kernel give the normal best effort behavior for "@expires+@delta",
   * but may decide to fire the timer earlier, but no earlier than @expires.
   *

   * You can set the task state as follows -
   *
   * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
   * pass before the routine returns.
   *
   * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
   * delivered to the current task.
   *
   * The current task state is guaranteed to be TASK_RUNNING when this
   * routine returns.
   *
   * Returns 0 when the timer has expired otherwise -EINTR
   */

  int __sched schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,

  			       const enum hrtimer_mode mode)
  {
  	struct hrtimer_sleeper t;
  
  	/*
  	 * Optimize when a zero timeout value is given. It does not
  	 * matter whether this is an absolute or a relative time.
  	 */
  	if (expires && !expires->tv64) {
  		__set_current_state(TASK_RUNNING);
  		return 0;
  	}
  
  	/*
  	 * A NULL parameter means "inifinte"
  	 */
  	if (!expires) {
  		schedule();
  		__set_current_state(TASK_RUNNING);
  		return -EINTR;
  	}
  
  	hrtimer_init_on_stack(&t.timer, CLOCK_MONOTONIC, mode);

  	hrtimer_set_expires_range_ns(&t.timer, *expires, delta);

  
  	hrtimer_init_sleeper(&t, current);

  	hrtimer_start_expires(&t.timer, mode);

  	if (!hrtimer_active(&t.timer))
  		t.task = NULL;
  
  	if (likely(t.task))
  		schedule();
  
  	hrtimer_cancel(&t.timer);
  	destroy_hrtimer_on_stack(&t.timer);
  
  	__set_current_state(TASK_RUNNING);
  
  	return !t.task ? 0 : -EINTR;
  }

  EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
  
  /**
   * schedule_hrtimeout - sleep until timeout
   * @expires:	timeout value (ktime_t)
   * @mode:	timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
   *
   * Make the current task sleep until the given expiry time has
   * elapsed. The routine will return immediately unless
   * the current task state has been set (see set_current_state()).
   *
   * You can set the task state as follows -
   *
   * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
   * pass before the routine returns.
   *
   * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
   * delivered to the current task.
   *
   * The current task state is guaranteed to be TASK_RUNNING when this
   * routine returns.
   *
   * Returns 0 when the timer has expired otherwise -EINTR
   */
  int __sched schedule_hrtimeout(ktime_t *expires,
  			       const enum hrtimer_mode mode)
  {
  	return schedule_hrtimeout_range(expires, 0, mode);
  }

  EXPORT_SYMBOL_GPL(schedule_hrtimeout);