/*
   *  linux/kernel/timer.c
   *

   *  Kernel internal timers, basic process system calls

   *
   *  Copyright (C) 1991, 1992  Linus Torvalds
   *
   *  1997-01-28  Modified by Finn Arne Gangstad to make timers scale better.
   *
   *  1997-09-10  Updated NTP code according to technical memorandum Jan '96
   *              "A Kernel Model for Precision Timekeeping" by Dave Mills
   *  1998-12-24  Fixed a xtime SMP race (we need the xtime_lock rw spinlock to
   *              serialize accesses to xtime/lost_ticks).
   *                              Copyright (C) 1998  Andrea Arcangeli
   *  1999-03-10  Improved NTP compatibility by Ulrich Windl
   *  2002-05-31	Move sys_sysinfo here and make its locking sane, Robert Love
   *  2000-10-05  Implemented scalable SMP per-CPU timer handling.
   *                              Copyright (C) 2000, 2001, 2002  Ingo Molnar
   *              Designed by David S. Miller, Alexey Kuznetsov and Ingo Molnar
   */
  
  #include <linux/kernel_stat.h>
  #include <linux/module.h>
  #include <linux/interrupt.h>
  #include <linux/percpu.h>
  #include <linux/init.h>
  #include <linux/mm.h>
  #include <linux/swap.h>

  #include <linux/pid_namespace.h>

  #include <linux/notifier.h>
  #include <linux/thread_info.h>
  #include <linux/time.h>
  #include <linux/jiffies.h>
  #include <linux/posix-timers.h>
  #include <linux/cpu.h>
  #include <linux/syscalls.h>

  #include <linux/delay.h>

  #include <linux/tick.h>

  #include <linux/kallsyms.h>

  
  #include <asm/uaccess.h>
  #include <asm/unistd.h>
  #include <asm/div64.h>
  #include <asm/timex.h>
  #include <asm/io.h>

  u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
  
  EXPORT_SYMBOL(jiffies_64);

  /*
   * per-CPU timer vector definitions:
   */

  #define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6)
  #define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8)
  #define TVN_SIZE (1 << TVN_BITS)
  #define TVR_SIZE (1 << TVR_BITS)
  #define TVN_MASK (TVN_SIZE - 1)
  #define TVR_MASK (TVR_SIZE - 1)
  
  typedef struct tvec_s {
  	struct list_head vec[TVN_SIZE];
  } tvec_t;
  
  typedef struct tvec_root_s {
  	struct list_head vec[TVR_SIZE];
  } tvec_root_t;
  
  struct tvec_t_base_s {

  	spinlock_t lock;
  	struct timer_list *running_timer;

  	unsigned long timer_jiffies;

  	tvec_root_t tv1;
  	tvec_t tv2;
  	tvec_t tv3;
  	tvec_t tv4;
  	tvec_t tv5;

  } ____cacheline_aligned;

  
  typedef struct tvec_t_base_s tvec_base_t;

  tvec_base_t boot_tvec_bases;
  EXPORT_SYMBOL(boot_tvec_bases);

  static DEFINE_PER_CPU(tvec_base_t *, tvec_bases) = &boot_tvec_bases;

  /*
   * Note that all tvec_bases is 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
   */
  #define TBASE_DEFERRABLE_FLAG		(0x1)
  
  /* Functions below help us manage 'deferrable' flag */
  static inline unsigned int tbase_get_deferrable(tvec_base_t *base)
  {

  	return ((unsigned int)(unsigned long)base & TBASE_DEFERRABLE_FLAG);

  }
  
  static inline tvec_base_t *tbase_get_base(tvec_base_t *base)
  {

  	return ((tvec_base_t *)((unsigned long)base & ~TBASE_DEFERRABLE_FLAG));

  }
  
  static inline void timer_set_deferrable(struct timer_list *timer)
  {

  	timer->base = ((tvec_base_t *)((unsigned long)(timer->base) |

  				       TBASE_DEFERRABLE_FLAG));

  }
  
  static inline void
  timer_set_base(struct timer_list *timer, tvec_base_t *new_base)
  {

  	timer->base = (tvec_base_t *)((unsigned long)(new_base) |

  				      tbase_get_deferrable(timer->base));

  }

  /**
   * __round_jiffies - function to round jiffies to a full second
   * @j: the time in (absolute) jiffies that should be rounded
   * @cpu: the processor number on which the timeout will happen
   *

   * __round_jiffies() rounds an absolute time in the future (in jiffies)

   * up or down to (approximately) full seconds. This is useful for timers
   * for which the exact time they fire does not matter too much, as long as
   * they fire approximately every X seconds.
   *
   * By rounding these timers to whole seconds, all such timers will fire
   * at the same time, rather than at various times spread out. The goal
   * of this is to have the CPU wake up less, which saves power.
   *
   * The exact rounding is skewed for each processor to avoid all
   * processors firing at the exact same time, which could lead
   * to lock contention or spurious cache line bouncing.
   *

   * The return value is the rounded version of the @j parameter.

   */
  unsigned long __round_jiffies(unsigned long j, int cpu)
  {
  	int rem;
  	unsigned long original = j;
  
  	/*
  	 * We don't want all cpus firing their timers at once hitting the
  	 * same lock or cachelines, so we skew each extra cpu with an extra
  	 * 3 jiffies. This 3 jiffies came originally from the mm/ code which
  	 * already did this.
  	 * The skew is done by adding 3*cpunr, then round, then subtract this
  	 * extra offset again.
  	 */
  	j += cpu * 3;
  
  	rem = j % HZ;
  
  	/*
  	 * If the target jiffie is just after a whole second (which can happen
  	 * due to delays of the timer irq, long irq off times etc etc) then
  	 * we should round down to the whole second, not up. Use 1/4th second
  	 * as cutoff for this rounding as an extreme upper bound for this.
  	 */
  	if (rem < HZ/4) /* round down */
  		j = j - rem;
  	else /* round up */
  		j = j - rem + HZ;
  
  	/* now that we have rounded, subtract the extra skew again */
  	j -= cpu * 3;
  
  	if (j <= jiffies) /* rounding ate our timeout entirely; */
  		return original;
  	return j;
  }
  EXPORT_SYMBOL_GPL(__round_jiffies);
  
  /**
   * __round_jiffies_relative - function to round jiffies to a full second
   * @j: the time in (relative) jiffies that should be rounded
   * @cpu: the processor number on which the timeout will happen
   *

   * __round_jiffies_relative() rounds a time delta  in the future (in jiffies)

   * up or down to (approximately) full seconds. This is useful for timers
   * for which the exact time they fire does not matter too much, as long as
   * they fire approximately every X seconds.
   *
   * By rounding these timers to whole seconds, all such timers will fire
   * at the same time, rather than at various times spread out. The goal
   * of this is to have the CPU wake up less, which saves power.
   *
   * The exact rounding is skewed for each processor to avoid all
   * processors firing at the exact same time, which could lead
   * to lock contention or spurious cache line bouncing.
   *

   * The return value is the rounded version of the @j parameter.

   */
  unsigned long __round_jiffies_relative(unsigned long j, int cpu)
  {
  	/*
  	 * In theory the following code can skip a jiffy in case jiffies
  	 * increments right between the addition and the later subtraction.
  	 * However since the entire point of this function is to use approximate
  	 * timeouts, it's entirely ok to not handle that.
  	 */
  	return  __round_jiffies(j + jiffies, cpu) - jiffies;
  }
  EXPORT_SYMBOL_GPL(__round_jiffies_relative);
  
  /**
   * round_jiffies - function to round jiffies to a full second
   * @j: the time in (absolute) jiffies that should be rounded
   *

   * round_jiffies() rounds an absolute time in the future (in jiffies)

   * up or down to (approximately) full seconds. This is useful for timers
   * for which the exact time they fire does not matter too much, as long as
   * they fire approximately every X seconds.
   *
   * By rounding these timers to whole seconds, all such timers will fire
   * at the same time, rather than at various times spread out. The goal
   * of this is to have the CPU wake up less, which saves power.
   *

   * The return value is the rounded version of the @j parameter.

   */
  unsigned long round_jiffies(unsigned long j)
  {
  	return __round_jiffies(j, raw_smp_processor_id());
  }
  EXPORT_SYMBOL_GPL(round_jiffies);
  
  /**
   * round_jiffies_relative - function to round jiffies to a full second
   * @j: the time in (relative) jiffies that should be rounded
   *

   * round_jiffies_relative() rounds a time delta  in the future (in jiffies)

   * up or down to (approximately) full seconds. This is useful for timers
   * for which the exact time they fire does not matter too much, as long as
   * they fire approximately every X seconds.
   *
   * By rounding these timers to whole seconds, all such timers will fire
   * at the same time, rather than at various times spread out. The goal
   * of this is to have the CPU wake up less, which saves power.
   *

   * The return value is the rounded version of the @j parameter.

   */
  unsigned long round_jiffies_relative(unsigned long j)
  {
  	return __round_jiffies_relative(j, raw_smp_processor_id());
  }
  EXPORT_SYMBOL_GPL(round_jiffies_relative);

  static inline void set_running_timer(tvec_base_t *base,
  					struct timer_list *timer)
  {
  #ifdef CONFIG_SMP

  	base->running_timer = timer;

  #endif
  }

  static void internal_add_timer(tvec_base_t *base, struct timer_list *timer)
  {
  	unsigned long expires = timer->expires;
  	unsigned long idx = expires - base->timer_jiffies;
  	struct list_head *vec;
  
  	if (idx < TVR_SIZE) {
  		int i = expires & TVR_MASK;
  		vec = base->tv1.vec + i;
  	} else if (idx < 1 << (TVR_BITS + TVN_BITS)) {
  		int i = (expires >> TVR_BITS) & TVN_MASK;
  		vec = base->tv2.vec + i;
  	} else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) {
  		int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK;
  		vec = base->tv3.vec + i;
  	} else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) {
  		int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK;
  		vec = base->tv4.vec + i;
  	} else if ((signed long) idx < 0) {
  		/*
  		 * Can happen if you add a timer with expires == jiffies,
  		 * or you set a timer to go off in the past
  		 */
  		vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK);
  	} else {
  		int i;
  		/* If the timeout is larger than 0xffffffff on 64-bit
  		 * architectures then we use the maximum timeout:
  		 */
  		if (idx > 0xffffffffUL) {
  			idx = 0xffffffffUL;
  			expires = idx + base->timer_jiffies;
  		}
  		i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK;
  		vec = base->tv5.vec + i;
  	}
  	/*
  	 * Timers are FIFO:
  	 */
  	list_add_tail(&timer->entry, vec);
  }

  #ifdef CONFIG_TIMER_STATS
  void __timer_stats_timer_set_start_info(struct timer_list *timer, void *addr)
  {
  	if (timer->start_site)
  		return;
  
  	timer->start_site = addr;
  	memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
  	timer->start_pid = current->pid;
  }

  
  static void timer_stats_account_timer(struct timer_list *timer)
  {
  	unsigned int flag = 0;
  
  	if (unlikely(tbase_get_deferrable(timer->base)))
  		flag |= TIMER_STATS_FLAG_DEFERRABLE;
  
  	timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
  				 timer->function, timer->start_comm, flag);
  }
  
  #else
  static void timer_stats_account_timer(struct timer_list *timer) {}

  #endif

  /**

   * init_timer - initialize a timer.
   * @timer: the timer to be initialized
   *
   * init_timer() must be done to a timer prior calling *any* of the
   * other timer functions.
   */
  void fastcall init_timer(struct timer_list *timer)
  {
  	timer->entry.next = NULL;

  	timer->base = __raw_get_cpu_var(tvec_bases);

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

  }
  EXPORT_SYMBOL(init_timer);

  void fastcall init_timer_deferrable(struct timer_list *timer)
  {
  	init_timer(timer);
  	timer_set_deferrable(timer);
  }
  EXPORT_SYMBOL(init_timer_deferrable);

  static inline void detach_timer(struct timer_list *timer,

  				int clear_pending)

  {
  	struct list_head *entry = &timer->entry;
  
  	__list_del(entry->prev, entry->next);
  	if (clear_pending)
  		entry->next = NULL;
  	entry->prev = LIST_POISON2;
  }
  
  /*

   * We are using hashed locking: holding per_cpu(tvec_bases).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 ->tvX lists.
   *
   * 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 tvec_base_t *lock_timer_base(struct timer_list *timer,

  					unsigned long *flags)

  	__acquires(timer->base->lock)

  {

  	tvec_base_t *base;

  
  	for (;;) {

  		tvec_base_t *prelock_base = timer->base;
  		base = tbase_get_base(prelock_base);

  		if (likely(base != NULL)) {
  			spin_lock_irqsave(&base->lock, *flags);

  			if (likely(prelock_base == timer->base))

  				return base;
  			/* The timer has migrated to another CPU */
  			spin_unlock_irqrestore(&base->lock, *flags);
  		}
  		cpu_relax();
  	}
  }

  int __mod_timer(struct timer_list *timer, unsigned long expires)
  {

  	tvec_base_t *base, *new_base;

  	unsigned long flags;
  	int ret = 0;

  	timer_stats_timer_set_start_info(timer);

  	BUG_ON(!timer->function);

  	base = lock_timer_base(timer, &flags);
  
  	if (timer_pending(timer)) {
  		detach_timer(timer, 0);
  		ret = 1;
  	}

  	new_base = __get_cpu_var(tvec_bases);

  	if (base != new_base) {

  		/*

  		 * We are trying to schedule the timer on the local CPU.
  		 * However we can't change timer's base while it is running,
  		 * otherwise del_timer_sync() can't detect that the timer's
  		 * handler yet has not finished. This also guarantees that
  		 * the timer is serialized wrt itself.

  		 */

  		if (likely(base->running_timer != timer)) {

  			/* See the comment in lock_timer_base() */

  			timer_set_base(timer, NULL);

  			spin_unlock(&base->lock);

  			base = new_base;
  			spin_lock(&base->lock);

  			timer_set_base(timer, base);

  		}
  	}

  	timer->expires = expires;

  	internal_add_timer(base, timer);
  	spin_unlock_irqrestore(&base->lock, flags);

  
  	return ret;
  }
  
  EXPORT_SYMBOL(__mod_timer);

  /**

   * add_timer_on - start a timer on a particular CPU
   * @timer: the timer to be added
   * @cpu: the CPU to start it on
   *
   * This is not very scalable on SMP. Double adds are not possible.
   */
  void add_timer_on(struct timer_list *timer, int cpu)
  {

  	tvec_base_t *base = per_cpu(tvec_bases, cpu);

  	unsigned long flags;

  	timer_stats_timer_set_start_info(timer);

  	BUG_ON(timer_pending(timer) || !timer->function);

  	spin_lock_irqsave(&base->lock, flags);

  	timer_set_base(timer, base);

  	internal_add_timer(base, timer);

  	spin_unlock_irqrestore(&base->lock, flags);

  }

  /**

   * mod_timer - modify a timer's timeout
   * @timer: the timer to be modified

   * @expires: new timeout in jiffies

   *

   * mod_timer() is a more efficient way to update the expire field of an

   * active timer (if the timer is inactive it will be activated)
   *
   * mod_timer(timer, expires) is equivalent to:
   *
   *     del_timer(timer); timer->expires = expires; add_timer(timer);
   *
   * Note that if there are multiple unserialized concurrent users of the
   * same timer, then mod_timer() is the only safe way to modify the timeout,
   * since add_timer() cannot modify an already running timer.
   *
   * The function returns whether it has modified a pending timer or not.
   * (ie. mod_timer() of an inactive timer returns 0, mod_timer() of an
   * active timer returns 1.)
   */
  int mod_timer(struct timer_list *timer, unsigned long expires)
  {
  	BUG_ON(!timer->function);

  	timer_stats_timer_set_start_info(timer);

  	/*
  	 * This is a common optimization triggered by the
  	 * networking code - if the timer is re-modified
  	 * to be the same thing then just return:
  	 */
  	if (timer->expires == expires && timer_pending(timer))
  		return 1;
  
  	return __mod_timer(timer, expires);
  }
  
  EXPORT_SYMBOL(mod_timer);

  /**

   * del_timer - deactive a timer.
   * @timer: the timer to be deactivated
   *
   * del_timer() deactivates a timer - this works on both active and inactive
   * timers.
   *
   * The function returns whether it has deactivated a pending timer or not.
   * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
   * active timer returns 1.)
   */
  int del_timer(struct timer_list *timer)
  {

  	tvec_base_t *base;

  	unsigned long flags;

  	int ret = 0;

  	timer_stats_timer_clear_start_info(timer);

  	if (timer_pending(timer)) {
  		base = lock_timer_base(timer, &flags);
  		if (timer_pending(timer)) {
  			detach_timer(timer, 1);
  			ret = 1;
  		}

  		spin_unlock_irqrestore(&base->lock, flags);

  	}

  	return ret;

  }
  
  EXPORT_SYMBOL(del_timer);
  
  #ifdef CONFIG_SMP

  /**
   * try_to_del_timer_sync - Try to deactivate a timer
   * @timer: timer do del
   *

   * This function tries to deactivate a timer. Upon successful (ret >= 0)
   * exit the timer is not queued and the handler is not running on any CPU.
   *
   * It must not be called from interrupt contexts.
   */
  int try_to_del_timer_sync(struct timer_list *timer)
  {

  	tvec_base_t *base;

  	unsigned long flags;
  	int ret = -1;
  
  	base = lock_timer_base(timer, &flags);
  
  	if (base->running_timer == timer)
  		goto out;
  
  	ret = 0;
  	if (timer_pending(timer)) {
  		detach_timer(timer, 1);
  		ret = 1;
  	}
  out:
  	spin_unlock_irqrestore(&base->lock, flags);
  
  	return ret;
  }

  EXPORT_SYMBOL(try_to_del_timer_sync);

  /**

   * del_timer_sync - deactivate a timer and wait for the handler to finish.
   * @timer: the timer to be deactivated
   *
   * This function only differs from del_timer() on SMP: besides deactivating
   * the timer it also makes sure the handler has finished executing on other
   * CPUs.
   *

   * Synchronization rules: Callers must prevent restarting of the timer,

   * otherwise this function is meaningless. It must not be called from
   * interrupt contexts. The caller must not hold locks which would prevent

   * completion of the timer's handler. The timer's handler must not call
   * add_timer_on(). Upon exit the timer is not queued and the handler is
   * not running on any CPU.

   *
   * The function returns whether it has deactivated a pending timer or not.

   */
  int del_timer_sync(struct timer_list *timer)
  {

  	for (;;) {
  		int ret = try_to_del_timer_sync(timer);
  		if (ret >= 0)
  			return ret;

  		cpu_relax();

  	}

  }

  EXPORT_SYMBOL(del_timer_sync);

  #endif
  
  static int cascade(tvec_base_t *base, tvec_t *tv, int index)
  {
  	/* cascade all the timers from tv up one level */

  	struct timer_list *timer, *tmp;
  	struct list_head tv_list;
  
  	list_replace_init(tv->vec + index, &tv_list);

  	/*

  	 * We are removing _all_ timers from the list, so we
  	 * don't have to detach them individually.

  	 */

  	list_for_each_entry_safe(timer, tmp, &tv_list, entry) {

  		BUG_ON(tbase_get_base(timer->base) != base);

  		internal_add_timer(base, timer);

  	}

  
  	return index;
  }

  #define INDEX(N) ((base->timer_jiffies >> (TVR_BITS + (N) * TVN_BITS)) & TVN_MASK)
  
  /**

   * __run_timers - run all expired timers (if any) on this CPU.
   * @base: the timer vector to be processed.
   *
   * This function cascades all vectors and executes all expired timer
   * vectors.
   */

  static inline void __run_timers(tvec_base_t *base)
  {
  	struct timer_list *timer;

  	spin_lock_irq(&base->lock);

  	while (time_after_eq(jiffies, base->timer_jiffies)) {

  		struct list_head work_list;

  		struct list_head *head = &work_list;

  		int index = base->timer_jiffies & TVR_MASK;

  		/*
  		 * Cascade timers:
  		 */
  		if (!index &&
  			(!cascade(base, &base->tv2, INDEX(0))) &&
  				(!cascade(base, &base->tv3, INDEX(1))) &&
  					!cascade(base, &base->tv4, INDEX(2)))
  			cascade(base, &base->tv5, INDEX(3));

  		++base->timer_jiffies;
  		list_replace_init(base->tv1.vec + index, &work_list);

  		while (!list_empty(head)) {

  			void (*fn)(unsigned long);
  			unsigned long data;

  			timer = list_first_entry(head, struct timer_list,entry);

  			fn = timer->function;
  			data = timer->data;

  			timer_stats_account_timer(timer);

  			set_running_timer(base, timer);

  			detach_timer(timer, 1);

  			spin_unlock_irq(&base->lock);

  			{

  				int preempt_count = preempt_count();

  				fn(data);
  				if (preempt_count != preempt_count()) {

  					printk(KERN_WARNING "huh, entered %p "
  					       "with preempt_count %08x, exited"
  					       " with %08x?
  ",
  					       fn, preempt_count,
  					       preempt_count());

  					BUG();
  				}
  			}

  			spin_lock_irq(&base->lock);

  		}
  	}
  	set_running_timer(base, NULL);

  	spin_unlock_irq(&base->lock);

  }

  #if defined(CONFIG_NO_IDLE_HZ) || defined(CONFIG_NO_HZ)

  /*
   * Find out when the next timer event is due to happen. This
   * is used on S/390 to stop all activity when a cpus is idle.
   * This functions needs to be called disabled.
   */

  static unsigned long __next_timer_interrupt(tvec_base_t *base)

  {

  	unsigned long timer_jiffies = base->timer_jiffies;

  	unsigned long expires = timer_jiffies + NEXT_TIMER_MAX_DELTA;

  	int index, slot, array, found = 0;

  	struct timer_list *nte;

  	tvec_t *varray[4];

  
  	/* Look for timer events in tv1. */

  	index = slot = timer_jiffies & TVR_MASK;

  	do {

  		list_for_each_entry(nte, base->tv1.vec + slot, entry) {

  			if (tbase_get_deferrable(nte->base))
  				continue;

  			found = 1;

  			expires = nte->expires;

  			/* Look at the cascade bucket(s)? */
  			if (!index || slot < index)
  				goto cascade;
  			return expires;

  		}

  		slot = (slot + 1) & TVR_MASK;
  	} while (slot != index);
  
  cascade:
  	/* Calculate the next cascade event */
  	if (index)
  		timer_jiffies += TVR_SIZE - index;
  	timer_jiffies >>= TVR_BITS;

  
  	/* Check tv2-tv5. */
  	varray[0] = &base->tv2;
  	varray[1] = &base->tv3;
  	varray[2] = &base->tv4;
  	varray[3] = &base->tv5;

  
  	for (array = 0; array < 4; array++) {
  		tvec_t *varp = varray[array];
  
  		index = slot = timer_jiffies & TVN_MASK;

  		do {

  			list_for_each_entry(nte, varp->vec + slot, entry) {
  				found = 1;

  				if (time_before(nte->expires, expires))
  					expires = nte->expires;

  			}
  			/*
  			 * Do we still search for the first timer or are
  			 * we looking up the cascade buckets ?
  			 */
  			if (found) {
  				/* Look at the cascade bucket(s)? */
  				if (!index || slot < index)
  					break;
  				return expires;
  			}
  			slot = (slot + 1) & TVN_MASK;
  		} while (slot != index);
  
  		if (index)
  			timer_jiffies += TVN_SIZE - index;
  		timer_jiffies >>= TVN_BITS;

  	}

  	return expires;
  }

  /*
   * Check, if the next hrtimer event is before the next timer wheel
   * event:
   */
  static unsigned long cmp_next_hrtimer_event(unsigned long now,
  					    unsigned long expires)
  {
  	ktime_t hr_delta = hrtimer_get_next_event();
  	struct timespec tsdelta;

  	unsigned long delta;

  
  	if (hr_delta.tv64 == KTIME_MAX)
  		return expires;

  	/*
  	 * Expired timer available, let it expire in the next tick
  	 */
  	if (hr_delta.tv64 <= 0)
  		return now + 1;

  	tsdelta = ktime_to_timespec(hr_delta);

  	delta = timespec_to_jiffies(&tsdelta);

  
  	/*
  	 * Limit the delta to the max value, which is checked in
  	 * tick_nohz_stop_sched_tick():
  	 */
  	if (delta > NEXT_TIMER_MAX_DELTA)
  		delta = NEXT_TIMER_MAX_DELTA;

  	/*
  	 * Take rounding errors in to account and make sure, that it
  	 * expires in the next tick. Otherwise we go into an endless
  	 * ping pong due to tick_nohz_stop_sched_tick() retriggering
  	 * the timer softirq
  	 */
  	if (delta < 1)
  		delta = 1;
  	now += delta;

  	if (time_before(now, expires))
  		return now;

  	return expires;
  }

  
  /**

   * get_next_timer_interrupt - return the jiffy of the next pending timer

   * @now: current time (in jiffies)

   */

  unsigned long get_next_timer_interrupt(unsigned long now)

  {
  	tvec_base_t *base = __get_cpu_var(tvec_bases);

  	unsigned long expires;

  
  	spin_lock(&base->lock);
  	expires = __next_timer_interrupt(base);
  	spin_unlock(&base->lock);
  
  	if (time_before_eq(expires, now))
  		return now;
  
  	return cmp_next_hrtimer_event(now, expires);
  }

  
  #ifdef CONFIG_NO_IDLE_HZ
  unsigned long next_timer_interrupt(void)
  {
  	return get_next_timer_interrupt(jiffies);
  }
  #endif

  #endif

  #ifndef CONFIG_VIRT_CPU_ACCOUNTING
  void account_process_tick(struct task_struct *p, int user_tick)
  {
  	if (user_tick) {
  		account_user_time(p, jiffies_to_cputime(1));
  		account_user_time_scaled(p, jiffies_to_cputime(1));
  	} else {
  		account_system_time(p, HARDIRQ_OFFSET, jiffies_to_cputime(1));
  		account_system_time_scaled(p, jiffies_to_cputime(1));
  	}
  }
  #endif

  /*

   * Called from the timer interrupt handler to charge one tick to the current

   * process.  user_tick is 1 if the tick is user time, 0 for system.
   */
  void update_process_times(int user_tick)
  {
  	struct task_struct *p = current;
  	int cpu = smp_processor_id();
  
  	/* Note: this timer irq context must be accounted for as well. */

  	account_process_tick(p, user_tick);

  	run_local_timers();
  	if (rcu_pending(cpu))
  		rcu_check_callbacks(cpu, user_tick);
  	scheduler_tick();

  	run_posix_cpu_timers(p);

  }
  
  /*
   * Nr of active tasks - counted in fixed-point numbers
   */
  static unsigned long count_active_tasks(void)
  {

  	return nr_active() * FIXED_1;

  }
  
  /*
   * Hmm.. Changed this, as the GNU make sources (load.c) seems to
   * imply that avenrun[] is the standard name for this kind of thing.
   * Nothing else seems to be standardized: the fractional size etc
   * all seem to differ on different machines.
   *
   * Requires xtime_lock to access.
   */
  unsigned long avenrun[3];
  
  EXPORT_SYMBOL(avenrun);
  
  /*
   * calc_load - given tick count, update the avenrun load estimates.
   * This is called while holding a write_lock on xtime_lock.
   */
  static inline void calc_load(unsigned long ticks)
  {
  	unsigned long active_tasks; /* fixed-point */
  	static int count = LOAD_FREQ;

  	count -= ticks;
  	if (unlikely(count < 0)) {
  		active_tasks = count_active_tasks();
  		do {
  			CALC_LOAD(avenrun[0], EXP_1, active_tasks);
  			CALC_LOAD(avenrun[1], EXP_5, active_tasks);
  			CALC_LOAD(avenrun[2], EXP_15, active_tasks);
  			count += LOAD_FREQ;
  		} while (count < 0);

  	}
  }

  /*

   * This function runs timers and the timer-tq in bottom half context.
   */
  static void run_timer_softirq(struct softirq_action *h)
  {

  	tvec_base_t *base = __get_cpu_var(tvec_bases);

  	hrtimer_run_queues();

  	if (time_after_eq(jiffies, base->timer_jiffies))
  		__run_timers(base);
  }
  
  /*
   * Called by the local, per-CPU timer interrupt on SMP.
   */
  void run_local_timers(void)
  {
  	raise_softirq(TIMER_SOFTIRQ);

  	softlockup_tick();

  }
  
  /*
   * Called by the timer interrupt. xtime_lock must already be taken
   * by the timer IRQ!
   */

  static inline void update_times(unsigned long ticks)

  {

  	update_wall_time();

  	calc_load(ticks);
  }

  /*
   * 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...
   */

  void do_timer(unsigned long ticks)

  {

  	jiffies_64 += ticks;
  	update_times(ticks);

  }
  
  #ifdef __ARCH_WANT_SYS_ALARM
  
  /*
   * For backwards compatibility?  This can be done in libc so Alpha
   * and all newer ports shouldn't need it.
   */
  asmlinkage unsigned long sys_alarm(unsigned int seconds)
  {

  	return alarm_setitimer(seconds);

  }
  
  #endif
  
  #ifndef __alpha__
  
  /*
   * The Alpha uses getxpid, getxuid, and getxgid instead.  Maybe this
   * should be moved into arch/i386 instead?
   */
  
  /**
   * sys_getpid - return the thread group id of the current process
   *
   * Note, despite the name, this returns the tgid not the pid.  The tgid and
   * the pid are identical unless CLONE_THREAD was specified on clone() in
   * which case the tgid is the same in all threads of the same group.
   *
   * This is SMP safe as current->tgid does not change.
   */
  asmlinkage long sys_getpid(void)
  {

  	return task_tgid_vnr(current);

  }
  
  /*

   * Accessing ->real_parent is not SMP-safe, it could
   * change from under us. However, we can use a stale
   * value of ->real_parent under rcu_read_lock(), see
   * release_task()->call_rcu(delayed_put_task_struct).

   */
  asmlinkage long sys_getppid(void)
  {
  	int pid;

  	rcu_read_lock();

  	pid = task_tgid_nr_ns(current->real_parent, current->nsproxy->pid_ns);

  	rcu_read_unlock();

  	return pid;
  }
  
  asmlinkage long sys_getuid(void)
  {
  	/* Only we change this so SMP safe */
  	return current->uid;
  }
  
  asmlinkage long sys_geteuid(void)
  {
  	/* Only we change this so SMP safe */
  	return current->euid;
  }
  
  asmlinkage long sys_getgid(void)
  {
  	/* Only we change this so SMP safe */
  	return current->gid;
  }
  
  asmlinkage long sys_getegid(void)
  {
  	/* Only we change this so SMP safe */
  	return  current->egid;
  }
  
  #endif
  
  static void process_timeout(unsigned long __data)
  {

  	wake_up_process((struct task_struct *)__data);

  }
  
  /**
   * schedule_timeout - sleep until timeout
   * @timeout: timeout value in jiffies
   *
   * Make the current task sleep until @timeout jiffies have
   * 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 jiffies are guaranteed to
   * pass before the routine returns. The routine will return 0
   *
   * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
   * delivered to the current task. In this case the remaining time
   * in jiffies will be returned, or 0 if the timer expired in time
   *
   * The current task state is guaranteed to be TASK_RUNNING when this
   * routine returns.
   *
   * Specifying a @timeout value of %MAX_SCHEDULE_TIMEOUT will schedule
   * the CPU away without a bound on the timeout. In this case the return
   * value will be %MAX_SCHEDULE_TIMEOUT.
   *
   * In all cases the return value is guaranteed to be non-negative.
   */
  fastcall signed long __sched schedule_timeout(signed long timeout)
  {
  	struct timer_list timer;
  	unsigned long expire;
  
  	switch (timeout)
  	{
  	case MAX_SCHEDULE_TIMEOUT:
  		/*
  		 * These two special cases are useful to be comfortable
  		 * in the caller. Nothing more. We could take
  		 * MAX_SCHEDULE_TIMEOUT from one of the negative value
  		 * but I' d like to return a valid offset (>=0) to allow
  		 * the caller to do everything it want with the retval.
  		 */
  		schedule();
  		goto out;
  	default:
  		/*
  		 * Another bit of PARANOID. Note that the retval will be
  		 * 0 since no piece of kernel is supposed to do a check
  		 * for a negative retval of schedule_timeout() (since it
  		 * should never happens anyway). You just have the printk()
  		 * that will tell you if something is gone wrong and where.
  		 */

  		if (timeout < 0) {

  			printk(KERN_ERR "schedule_timeout: wrong timeout "

  				"value %lx
  ", timeout);
  			dump_stack();

  			current->state = TASK_RUNNING;
  			goto out;
  		}
  	}
  
  	expire = timeout + jiffies;

  	setup_timer(&timer, process_timeout, (unsigned long)current);
  	__mod_timer(&timer, expire);

  	schedule();
  	del_singleshot_timer_sync(&timer);
  
  	timeout = expire - jiffies;
  
   out:
  	return timeout < 0 ? 0 : timeout;
  }

  EXPORT_SYMBOL(schedule_timeout);

  /*
   * We can use __set_current_state() here because schedule_timeout() calls
   * schedule() unconditionally.
   */

  signed long __sched schedule_timeout_interruptible(signed long timeout)
  {

  	__set_current_state(TASK_INTERRUPTIBLE);
  	return schedule_timeout(timeout);

  }
  EXPORT_SYMBOL(schedule_timeout_interruptible);
  
  signed long __sched schedule_timeout_uninterruptible(signed long timeout)
  {

  	__set_current_state(TASK_UNINTERRUPTIBLE);
  	return schedule_timeout(timeout);

  }
  EXPORT_SYMBOL(schedule_timeout_uninterruptible);

  /* Thread ID - the internal kernel "pid" */
  asmlinkage long sys_gettid(void)
  {

  	return task_pid_vnr(current);

  }

  /**

   * do_sysinfo - fill in sysinfo struct

   * @info: pointer to buffer to fill

   */

  int do_sysinfo(struct sysinfo *info)

  {

  	unsigned long mem_total, sav_total;
  	unsigned int mem_unit, bitcount;
  	unsigned long seq;

  	memset(info, 0, sizeof(struct sysinfo));

  
  	do {
  		struct timespec tp;
  		seq = read_seqbegin(&xtime_lock);
  
  		/*
  		 * This is annoying.  The below is the same thing
  		 * posix_get_clock_monotonic() does, but it wants to
  		 * take the lock which we want to cover the loads stuff
  		 * too.
  		 */
  
  		getnstimeofday(&tp);
  		tp.tv_sec += wall_to_monotonic.tv_sec;
  		tp.tv_nsec += wall_to_monotonic.tv_nsec;

  		monotonic_to_bootbased(&tp);

  		if (tp.tv_nsec - NSEC_PER_SEC >= 0) {
  			tp.tv_nsec = tp.tv_nsec - NSEC_PER_SEC;
  			tp.tv_sec++;
  		}

  		info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);

  		info->loads[0] = avenrun[0] << (SI_LOAD_SHIFT - FSHIFT);
  		info->loads[1] = avenrun[1] << (SI_LOAD_SHIFT - FSHIFT);
  		info->loads[2] = avenrun[2] << (SI_LOAD_SHIFT - FSHIFT);

  		info->procs = nr_threads;

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

  	si_meminfo(info);
  	si_swapinfo(info);

  
  	/*
  	 * If the sum of all the available memory (i.e. ram + swap)
  	 * is less than can be stored in a 32 bit unsigned long then
  	 * we can be binary compatible with 2.2.x kernels.  If not,
  	 * well, in that case 2.2.x was broken anyways...
  	 *
  	 *  -Erik Andersen <andersee@debian.org>
  	 */

  	mem_total = info->totalram + info->totalswap;
  	if (mem_total < info->totalram || mem_total < info->totalswap)

  		goto out;
  	bitcount = 0;

  	mem_unit = info->mem_unit;

  	while (mem_unit > 1) {
  		bitcount++;
  		mem_unit >>= 1;
  		sav_total = mem_total;
  		mem_total <<= 1;
  		if (mem_total < sav_total)
  			goto out;
  	}
  
  	/*
  	 * If mem_total did not overflow, multiply all memory values by

  	 * info->mem_unit and set it to 1.  This leaves things compatible

  	 * with 2.2.x, and also retains compatibility with earlier 2.4.x
  	 * kernels...
  	 */

  	info->mem_unit = 1;
  	info->totalram <<= bitcount;
  	info->freeram <<= bitcount;
  	info->sharedram <<= bitcount;
  	info->bufferram <<= bitcount;
  	info->totalswap <<= bitcount;
  	info->freeswap <<= bitcount;
  	info->totalhigh <<= bitcount;
  	info->freehigh <<= bitcount;
  
  out:
  	return 0;
  }
  
  asmlinkage long sys_sysinfo(struct sysinfo __user *info)
  {
  	struct sysinfo val;
  
  	do_sysinfo(&val);

  	if (copy_to_user(info, &val, sizeof(struct sysinfo)))
  		return -EFAULT;
  
  	return 0;
  }

  /*
   * lockdep: we want to track each per-CPU base as a separate lock-class,
   * but timer-bases are kmalloc()-ed, so we need to attach separate
   * keys to them:
   */
  static struct lock_class_key base_lock_keys[NR_CPUS];

  static int __cpuinit init_timers_cpu(int cpu)

  {
  	int j;
  	tvec_base_t *base;

  	static char __cpuinitdata tvec_base_done[NR_CPUS];

  	if (!tvec_base_done[cpu]) {

  		static char boot_done;

  		if (boot_done) {

  			/*
  			 * The APs use this path later in boot
  			 */

  			base = kmalloc_node(sizeof(*base),
  						GFP_KERNEL | __GFP_ZERO,

  						cpu_to_node(cpu));
  			if (!base)
  				return -ENOMEM;

  
  			/* Make sure that tvec_base is 2 byte aligned */
  			if (tbase_get_deferrable(base)) {
  				WARN_ON(1);
  				kfree(base);
  				return -ENOMEM;
  			}

  			per_cpu(tvec_bases, cpu) = base;

  		} else {

  			/*
  			 * This is for the boot CPU - we use compile-time
  			 * static initialisation because per-cpu memory isn't
  			 * ready yet and because the memory allocators are not
  			 * initialised either.
  			 */

  			boot_done = 1;

  			base = &boot_tvec_bases;

  		}

  		tvec_base_done[cpu] = 1;
  	} else {
  		base = per_cpu(tvec_bases, cpu);

  	}

  	spin_lock_init(&base->lock);

  	lockdep_set_class(&base->lock, base_lock_keys + cpu);

  	for (j = 0; j < TVN_SIZE; j++) {
  		INIT_LIST_HEAD(base->tv5.vec + j);
  		INIT_LIST_HEAD(base->tv4.vec + j);
  		INIT_LIST_HEAD(base->tv3.vec + j);
  		INIT_LIST_HEAD(base->tv2.vec + j);
  	}
  	for (j = 0; j < TVR_SIZE; j++)
  		INIT_LIST_HEAD(base->tv1.vec + j);
  
  	base->timer_jiffies = jiffies;

  	return 0;

  }
  
  #ifdef CONFIG_HOTPLUG_CPU

  static void migrate_timer_list(tvec_base_t *new_base, struct list_head *head)

  {
  	struct timer_list *timer;
  
  	while (!list_empty(head)) {

  		timer = list_first_entry(head, struct timer_list, entry);

  		detach_timer(timer, 0);

  		timer_set_base(timer, new_base);

  		internal_add_timer(new_base, timer);

  	}

  }
  
  static void __devinit migrate_timers(int cpu)
  {
  	tvec_base_t *old_base;
  	tvec_base_t *new_base;
  	int i;
  
  	BUG_ON(cpu_online(cpu));

  	old_base = per_cpu(tvec_bases, cpu);
  	new_base = get_cpu_var(tvec_bases);

  
  	local_irq_disable();

  	double_spin_lock(&new_base->lock, &old_base->lock,
  			 smp_processor_id() < cpu);

  
  	BUG_ON(old_base->running_timer);

  	for (i = 0; i < TVR_SIZE; i++)

  		migrate_timer_list(new_base, old_base->tv1.vec + i);
  	for (i = 0; i < TVN_SIZE; i++) {
  		migrate_timer_list(new_base, old_base->tv2.vec + i);
  		migrate_timer_list(new_base, old_base->tv3.vec + i);
  		migrate_timer_list(new_base, old_base->tv4.vec + i);
  		migrate_timer_list(new_base, old_base->tv5.vec + i);
  	}

  	double_spin_unlock(&new_base->lock, &old_base->lock,
  			   smp_processor_id() < cpu);

  	local_irq_enable();
  	put_cpu_var(tvec_bases);

  }
  #endif /* CONFIG_HOTPLUG_CPU */

  static int __cpuinit timer_cpu_notify(struct notifier_block *self,

  				unsigned long action, void *hcpu)
  {
  	long cpu = (long)hcpu;
  	switch(action) {
  	case CPU_UP_PREPARE:

  	case CPU_UP_PREPARE_FROZEN:

  		if (init_timers_cpu(cpu) < 0)
  			return NOTIFY_BAD;

  		break;
  #ifdef CONFIG_HOTPLUG_CPU
  	case CPU_DEAD:

  	case CPU_DEAD_FROZEN:

  		migrate_timers(cpu);
  		break;
  #endif
  	default:
  		break;
  	}
  	return NOTIFY_OK;
  }

  static struct notifier_block __cpuinitdata timers_nb = {

  	.notifier_call	= timer_cpu_notify,
  };
  
  
  void __init init_timers(void)
  {

  	int err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,

  				(void *)(long)smp_processor_id());

  	init_timer_stats();

  	BUG_ON(err == NOTIFY_BAD);

  	register_cpu_notifier(&timers_nb);
  	open_softirq(TIMER_SOFTIRQ, run_timer_softirq, NULL);
  }

  /**
   * msleep - sleep safely even with waitqueue interruptions
   * @msecs: Time in milliseconds to sleep for
   */
  void msleep(unsigned int msecs)
  {
  	unsigned long timeout = msecs_to_jiffies(msecs) + 1;

  	while (timeout)
  		timeout = schedule_timeout_uninterruptible(timeout);

  }
  
  EXPORT_SYMBOL(msleep);
  
  /**

   * msleep_interruptible - sleep waiting for signals

   * @msecs: Time in milliseconds to sleep for
   */
  unsigned long msleep_interruptible(unsigned int msecs)
  {
  	unsigned long timeout = msecs_to_jiffies(msecs) + 1;

  	while (timeout && !signal_pending(current))
  		timeout = schedule_timeout_interruptible(timeout);

  	return jiffies_to_msecs(timeout);
  }
  
  EXPORT_SYMBOL(msleep_interruptible);