FreeBSD/Linux Kernel Cross Reference
sys/kernel/timer.c

     /*
      *  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/export.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 <linux/irq_work.h>
    #include <linux/sched.h>
    #include <linux/slab.h>
    
    #include <asm/uaccess.h>
    #include <asm/unistd.h>
    #include <asm/div64.h>
    #include <asm/timex.h>
    #include <asm/io.h>
    
    #define CREATE_TRACE_POINTS
    #include <trace/events/timer.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)
    #define MAX_TVAL ((unsigned long)((1ULL << (TVR_BITS + 4*TVN_BITS)) - 1))
    
    struct tvec {
            struct list_head vec[TVN_SIZE];
    };
    
    struct tvec_root {
            struct list_head vec[TVR_SIZE];
    };
    
    struct tvec_base {
            spinlock_t lock;
            struct timer_list *running_timer;
            unsigned long timer_jiffies;
            unsigned long next_timer;
            unsigned long active_timers;
            struct tvec_root tv1;
            struct tvec tv2;
            struct tvec tv3;
            struct tvec tv4;
            struct tvec tv5;
    } ____cacheline_aligned;
    
    struct tvec_base boot_tvec_bases;
    EXPORT_SYMBOL(boot_tvec_bases);
    static DEFINE_PER_CPU(struct tvec_base *, tvec_bases) = &boot_tvec_bases;
    
    /* Functions below help us manage 'deferrable' flag */
    static inline unsigned int tbase_get_deferrable(struct tvec_base *base)
    {
            return ((unsigned int)(unsigned long)base & TIMER_DEFERRABLE);
    }
    
    static inline unsigned int tbase_get_irqsafe(struct tvec_base *base)
   {
           return ((unsigned int)(unsigned long)base & TIMER_IRQSAFE);
   }
   
   static inline struct tvec_base *tbase_get_base(struct tvec_base *base)
   {
           return ((struct tvec_base *)((unsigned long)base & ~TIMER_FLAG_MASK));
   }
   
   static inline void
   timer_set_base(struct timer_list *timer, struct tvec_base *new_base)
   {
           unsigned long flags = (unsigned long)timer->base & TIMER_FLAG_MASK;
   
           timer->base = (struct tvec_base *)((unsigned long)(new_base) | flags);
   }
   
   static unsigned long round_jiffies_common(unsigned long j, int cpu,
                   bool force_up)
   {
           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.
            * But never round down if @force_up is set.
            */
           if (rem < HZ/4 && !force_up) /* 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;
   }
   
   /**
    * __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)
   {
           return round_jiffies_common(j, cpu, false);
   }
   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)
   {
           unsigned long j0 = jiffies;
   
           /* Use j0 because jiffies might change while we run */
           return round_jiffies_common(j + j0, cpu, false) - j0;
   }
   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_common(j, raw_smp_processor_id(), false);
   }
   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);
   
   /**
    * __round_jiffies_up - function to round jiffies up to a full second
    * @j: the time in (absolute) jiffies that should be rounded
    * @cpu: the processor number on which the timeout will happen
    *
    * This is the same as __round_jiffies() except that it will never
    * round down.  This is useful for timeouts for which the exact time
    * of firing does not matter too much, as long as they don't fire too
    * early.
    */
   unsigned long __round_jiffies_up(unsigned long j, int cpu)
   {
           return round_jiffies_common(j, cpu, true);
   }
   EXPORT_SYMBOL_GPL(__round_jiffies_up);
   
   /**
    * __round_jiffies_up_relative - function to round jiffies up to a full second
    * @j: the time in (relative) jiffies that should be rounded
    * @cpu: the processor number on which the timeout will happen
    *
    * This is the same as __round_jiffies_relative() except that it will never
    * round down.  This is useful for timeouts for which the exact time
    * of firing does not matter too much, as long as they don't fire too
    * early.
    */
   unsigned long __round_jiffies_up_relative(unsigned long j, int cpu)
   {
           unsigned long j0 = jiffies;
   
           /* Use j0 because jiffies might change while we run */
           return round_jiffies_common(j + j0, cpu, true) - j0;
   }
   EXPORT_SYMBOL_GPL(__round_jiffies_up_relative);
   
   /**
    * round_jiffies_up - function to round jiffies up to a full second
    * @j: the time in (absolute) jiffies that should be rounded
    *
    * This is the same as round_jiffies() except that it will never
    * round down.  This is useful for timeouts for which the exact time
    * of firing does not matter too much, as long as they don't fire too
    * early.
    */
   unsigned long round_jiffies_up(unsigned long j)
   {
           return round_jiffies_common(j, raw_smp_processor_id(), true);
   }
   EXPORT_SYMBOL_GPL(round_jiffies_up);
   
   /**
    * round_jiffies_up_relative - function to round jiffies up to a full second
    * @j: the time in (relative) jiffies that should be rounded
    *
    * This is the same as round_jiffies_relative() except that it will never
    * round down.  This is useful for timeouts for which the exact time
    * of firing does not matter too much, as long as they don't fire too
    * early.
    */
   unsigned long round_jiffies_up_relative(unsigned long j)
   {
           return __round_jiffies_up_relative(j, raw_smp_processor_id());
   }
   EXPORT_SYMBOL_GPL(round_jiffies_up_relative);
   
   /**
    * set_timer_slack - set the allowed slack for a timer
    * @timer: the timer to be modified
    * @slack_hz: the amount of time (in jiffies) allowed for rounding
    *
    * Set the amount of time, in jiffies, that a certain timer has
    * in terms of slack. By setting this value, the timer subsystem
    * will schedule the actual timer somewhere between
    * the time mod_timer() asks for, and that time plus the slack.
    *
    * By setting the slack to -1, a percentage of the delay is used
    * instead.
    */
   void set_timer_slack(struct timer_list *timer, int slack_hz)
   {
           timer->slack = slack_hz;
   }
   EXPORT_SYMBOL_GPL(set_timer_slack);
   
   static void
   __internal_add_timer(struct tvec_base *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 MAX_TVAL (on 64-bit
                    * architectures or with CONFIG_BASE_SMALL=1) then we
                    * use the maximum timeout.
                    */
                   if (idx > MAX_TVAL) {
                           idx = MAX_TVAL;
                           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);
   }
   
   static void internal_add_timer(struct tvec_base *base, struct timer_list *timer)
   {
           __internal_add_timer(base, timer);
           /*
            * Update base->active_timers and base->next_timer
            */
           if (!tbase_get_deferrable(timer->base)) {
                   if (time_before(timer->expires, base->next_timer))
                           base->next_timer = timer->expires;
                   base->active_timers++;
           }
   }
   
   #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 (likely(!timer->start_site))
                   return;
           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
   
   #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
   
   static struct debug_obj_descr timer_debug_descr;
   
   static void *timer_debug_hint(void *addr)
   {
           return ((struct timer_list *) addr)->function;
   }
   
   /*
    * fixup_init is called when:
    * - an active object is initialized
    */
   static int timer_fixup_init(void *addr, enum debug_obj_state state)
   {
           struct timer_list *timer = addr;
   
           switch (state) {
           case ODEBUG_STATE_ACTIVE:
                   del_timer_sync(timer);
                   debug_object_init(timer, &timer_debug_descr);
                   return 1;
           default:
                   return 0;
           }
   }
   
   /* Stub timer callback for improperly used timers. */
   static void stub_timer(unsigned long data)
   {
           WARN_ON(1);
   }
   
   /*
    * fixup_activate is called when:
    * - an active object is activated
    * - an unknown object is activated (might be a statically initialized object)
    */
   static int timer_fixup_activate(void *addr, enum debug_obj_state state)
   {
           struct timer_list *timer = addr;
   
           switch (state) {
   
           case ODEBUG_STATE_NOTAVAILABLE:
                   /*
                    * This is not really a fixup. The timer was
                    * statically initialized. We just make sure that it
                    * is tracked in the object tracker.
                    */
                   if (timer->entry.next == NULL &&
                       timer->entry.prev == TIMER_ENTRY_STATIC) {
                           debug_object_init(timer, &timer_debug_descr);
                           debug_object_activate(timer, &timer_debug_descr);
                           return 0;
                   } else {
                           setup_timer(timer, stub_timer, 0);
                           return 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 timer_fixup_free(void *addr, enum debug_obj_state state)
   {
           struct timer_list *timer = addr;
   
           switch (state) {
           case ODEBUG_STATE_ACTIVE:
                   del_timer_sync(timer);
                   debug_object_free(timer, &timer_debug_descr);
                   return 1;
           default:
                   return 0;
           }
   }
   
   /*
    * fixup_assert_init is called when:
    * - an untracked/uninit-ed object is found
    */
   static int timer_fixup_assert_init(void *addr, enum debug_obj_state state)
   {
           struct timer_list *timer = addr;
   
           switch (state) {
           case ODEBUG_STATE_NOTAVAILABLE:
                   if (timer->entry.prev == TIMER_ENTRY_STATIC) {
                           /*
                            * This is not really a fixup. The timer was
                            * statically initialized. We just make sure that it
                            * is tracked in the object tracker.
                            */
                           debug_object_init(timer, &timer_debug_descr);
                           return 0;
                   } else {
                           setup_timer(timer, stub_timer, 0);
                           return 1;
                   }
           default:
                   return 0;
           }
   }
   
   static struct debug_obj_descr timer_debug_descr = {
           .name                   = "timer_list",
           .debug_hint             = timer_debug_hint,
           .fixup_init             = timer_fixup_init,
           .fixup_activate         = timer_fixup_activate,
           .fixup_free             = timer_fixup_free,
           .fixup_assert_init      = timer_fixup_assert_init,
   };
   
   static inline void debug_timer_init(struct timer_list *timer)
   {
           debug_object_init(timer, &timer_debug_descr);
   }
   
   static inline void debug_timer_activate(struct timer_list *timer)
   {
           debug_object_activate(timer, &timer_debug_descr);
   }
   
   static inline void debug_timer_deactivate(struct timer_list *timer)
   {
           debug_object_deactivate(timer, &timer_debug_descr);
   }
   
   static inline void debug_timer_free(struct timer_list *timer)
   {
           debug_object_free(timer, &timer_debug_descr);
   }
   
   static inline void debug_timer_assert_init(struct timer_list *timer)
   {
           debug_object_assert_init(timer, &timer_debug_descr);
   }
   
   static void do_init_timer(struct timer_list *timer, unsigned int flags,
                             const char *name, struct lock_class_key *key);
   
   void init_timer_on_stack_key(struct timer_list *timer, unsigned int flags,
                                const char *name, struct lock_class_key *key)
   {
           debug_object_init_on_stack(timer, &timer_debug_descr);
           do_init_timer(timer, flags, name, key);
   }
   EXPORT_SYMBOL_GPL(init_timer_on_stack_key);
   
   void destroy_timer_on_stack(struct timer_list *timer)
   {
           debug_object_free(timer, &timer_debug_descr);
   }
   EXPORT_SYMBOL_GPL(destroy_timer_on_stack);
   
   #else
   static inline void debug_timer_init(struct timer_list *timer) { }
   static inline void debug_timer_activate(struct timer_list *timer) { }
   static inline void debug_timer_deactivate(struct timer_list *timer) { }
   static inline void debug_timer_assert_init(struct timer_list *timer) { }
   #endif
   
   static inline void debug_init(struct timer_list *timer)
   {
           debug_timer_init(timer);
           trace_timer_init(timer);
   }
   
   static inline void
   debug_activate(struct timer_list *timer, unsigned long expires)
   {
           debug_timer_activate(timer);
           trace_timer_start(timer, expires);
   }
   
   static inline void debug_deactivate(struct timer_list *timer)
   {
           debug_timer_deactivate(timer);
           trace_timer_cancel(timer);
   }
   
   static inline void debug_assert_init(struct timer_list *timer)
   {
           debug_timer_assert_init(timer);
   }
   
   static void do_init_timer(struct timer_list *timer, unsigned int flags,
                             const char *name, struct lock_class_key *key)
   {
           struct tvec_base *base = __raw_get_cpu_var(tvec_bases);
   
           timer->entry.next = NULL;
           timer->base = (void *)((unsigned long)base | flags);
           timer->slack = -1;
   #ifdef CONFIG_TIMER_STATS
           timer->start_site = NULL;
           timer->start_pid = -1;
           memset(timer->start_comm, 0, TASK_COMM_LEN);
   #endif
           lockdep_init_map(&timer->lockdep_map, name, key, 0);
   }
   
   /**
    * init_timer_key - initialize a timer
    * @timer: the timer to be initialized
    * @flags: timer flags
    * @name: name of the timer
    * @key: lockdep class key of the fake lock used for tracking timer
    *       sync lock dependencies
    *
    * init_timer_key() must be done to a timer prior calling *any* of the
    * other timer functions.
    */
   void init_timer_key(struct timer_list *timer, unsigned int flags,
                       const char *name, struct lock_class_key *key)
   {
           debug_init(timer);
           do_init_timer(timer, flags, name, key);
   }
   EXPORT_SYMBOL(init_timer_key);
   
   static inline void detach_timer(struct timer_list *timer, bool clear_pending)
   {
           struct list_head *entry = &timer->entry;
   
           debug_deactivate(timer);
   
           __list_del(entry->prev, entry->next);
           if (clear_pending)
                   entry->next = NULL;
           entry->prev = LIST_POISON2;
   }
   
   static inline void
   detach_expired_timer(struct timer_list *timer, struct tvec_base *base)
   {
           detach_timer(timer, true);
           if (!tbase_get_deferrable(timer->base))
                   base->active_timers--;
   }
   
   static int detach_if_pending(struct timer_list *timer, struct tvec_base *base,
                                bool clear_pending)
   {
           if (!timer_pending(timer))
                   return 0;
   
           detach_timer(timer, clear_pending);
           if (!tbase_get_deferrable(timer->base)) {
                   base->active_timers--;
                   if (timer->expires == base->next_timer)
                           base->next_timer = base->timer_jiffies;
           }
           return 1;
   }
   
   /*
    * 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 struct tvec_base *lock_timer_base(struct timer_list *timer,
                                           unsigned long *flags)
           __acquires(timer->base->lock)
   {
           struct tvec_base *base;
   
           for (;;) {
                   struct tvec_base *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();
           }
   }
   
   static inline int
   __mod_timer(struct timer_list *timer, unsigned long expires,
                                                   bool pending_only, int pinned)
   {
           struct tvec_base *base, *new_base;
           unsigned long flags;
           int ret = 0 , cpu;
   
           timer_stats_timer_set_start_info(timer);
           BUG_ON(!timer->function);
   
           base = lock_timer_base(timer, &flags);
   
           ret = detach_if_pending(timer, base, false);
           if (!ret && pending_only)
                   goto out_unlock;
   
           debug_activate(timer, expires);
   
           cpu = smp_processor_id();
   
   #if defined(CONFIG_NO_HZ) && defined(CONFIG_SMP)
           if (!pinned && get_sysctl_timer_migration() && idle_cpu(cpu))
                   cpu = get_nohz_timer_target();
   #endif
           new_base = per_cpu(tvec_bases, cpu);
   
           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);
   
   out_unlock:
           spin_unlock_irqrestore(&base->lock, flags);
   
           return ret;
   }
   
   /**
    * mod_timer_pending - modify a pending timer's timeout
    * @timer: the pending timer to be modified
    * @expires: new timeout in jiffies
    *
    * mod_timer_pending() is the same for pending timers as mod_timer(),
    * but will not re-activate and modify already deleted timers.
    *
    * It is useful for unserialized use of timers.
    */
   int mod_timer_pending(struct timer_list *timer, unsigned long expires)
   {
           return __mod_timer(timer, expires, true, TIMER_NOT_PINNED);
   }
   EXPORT_SYMBOL(mod_timer_pending);
   
   /*
    * Decide where to put the timer while taking the slack into account
    *
    * Algorithm:
    *   1) calculate the maximum (absolute) time
    *   2) calculate the highest bit where the expires and new max are different
    *   3) use this bit to make a mask
    *   4) use the bitmask to round down the maximum time, so that all last
    *      bits are zeros
    */
   static inline
   unsigned long apply_slack(struct timer_list *timer, unsigned long expires)
   {
           unsigned long expires_limit, mask;
           int bit;
   
           if (timer->slack >= 0) {
                   expires_limit = expires + timer->slack;
           } else {
                   long delta = expires - jiffies;
   
                   if (delta < 256)
                           return expires;
   
                   expires_limit = expires + delta / 256;
           }
           mask = expires ^ expires_limit;
           if (mask == 0)
                   return expires;
   
           bit = find_last_bit(&mask, BITS_PER_LONG);
   
           mask = (1 << bit) - 1;
   
           expires_limit = expires_limit & ~(mask);
   
           return expires_limit;
   }
   
   /**
    * 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)
   {
           expires = apply_slack(timer, expires);
   
           /*
            * 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_pending(timer) && timer->expires == expires)
                   return 1;
   
           return __mod_timer(timer, expires, false, TIMER_NOT_PINNED);
   }
   EXPORT_SYMBOL(mod_timer);
   
   /**
    * mod_timer_pinned - modify a timer's timeout
    * @timer: the timer to be modified
    * @expires: new timeout in jiffies
    *
    * mod_timer_pinned() is a way to update the expire field of an
    * active timer (if the timer is inactive it will be activated)
    * and to ensure that the timer is scheduled on the current CPU.
    *
    * Note that this does not prevent the timer from being migrated
    * when the current CPU goes offline.  If this is a problem for
    * you, use CPU-hotplug notifiers to handle it correctly, for
    * example, cancelling the timer when the corresponding CPU goes
    * offline.
    *
    * mod_timer_pinned(timer, expires) is equivalent to:
    *
    *     del_timer(timer); timer->expires = expires; add_timer(timer);
    */
   int mod_timer_pinned(struct timer_list *timer, unsigned long expires)
   {
           if (timer->expires == expires && timer_pending(timer))
                   return 1;
   
           return __mod_timer(timer, expires, false, TIMER_PINNED);
   }
   EXPORT_SYMBOL(mod_timer_pinned);
   
   /**
    * add_timer - start a timer
    * @timer: the timer to be added
    *
    * The kernel will do a ->function(->data) callback from the
    * timer interrupt at the ->expires point in the future. The
    * current time is 'jiffies'.
    *
    * The timer's ->expires, ->function (and if the handler uses it, ->data)
    * fields must be set prior calling this function.
    *
    * Timers with an ->expires field in the past will be executed in the next
    * timer tick.
    */
   void add_timer(struct timer_list *timer)
   {
           BUG_ON(timer_pending(timer));
           mod_timer(timer, timer->expires);
   }
   EXPORT_SYMBOL(add_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)
   {
           struct tvec_base *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);
           debug_activate(timer, timer->expires);
           internal_add_timer(base, timer);
           /*
            * Check whether the other CPU is idle and needs to be
            * triggered to reevaluate the timer wheel when nohz is
            * active. We are protected against the other CPU fiddling
            * with the timer by holding the timer base lock. This also
            * makes sure that a CPU on the way to idle can not evaluate
            * the timer wheel.
            */
           wake_up_idle_cpu(cpu);
           spin_unlock_irqrestore(&base->lock, flags);
   }
   EXPORT_SYMBOL_GPL(add_timer_on);
   
   /**
    * 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)
   {
           struct tvec_base *base;
           unsigned long flags;
           int ret = 0;
   
           debug_assert_init(timer);
   
           timer_stats_timer_clear_start_info(timer);
           if (timer_pending(timer)) {
                   base = lock_timer_base(timer, &flags);
                   ret = detach_if_pending(timer, base, true);
                   spin_unlock_irqrestore(&base->lock, flags);
           }
   
           return ret;
   }
   EXPORT_SYMBOL(del_timer);
   
   /**
    * 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.
    */
   int try_to_del_timer_sync(struct timer_list *timer)
   {
           struct tvec_base *base;
           unsigned long flags;
           int ret = -1;
   
           debug_assert_init(timer);
   
           base = lock_timer_base(timer, &flags);
   
           if (base->running_timer != timer) {
                   timer_stats_timer_clear_start_info(timer);
                   ret = detach_if_pending(timer, base, true);
           }
           spin_unlock_irqrestore(&base->lock, flags);
   
           return ret;
   }
   EXPORT_SYMBOL(try_to_del_timer_sync);
  
  #ifdef CONFIG_SMP
  /**
   * 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 unless the timer is an irqsafe one. 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.
   *
   * Note: For !irqsafe timers, you must not hold locks that are held in
   *   interrupt context while calling this function. Even if the lock has
   *   nothing to do with the timer in question.  Here's why:
   *
   *    CPU0                             CPU1
   *    ----                             ----
   *                                   <SOFTIRQ>
   *                                   call_timer_fn();
   *                                     base->running_timer = mytimer;
   *  spin_lock_irq(somelock);
   *                                     <IRQ>
   *                                        spin_lock(somelock);
   *  del_timer_sync(mytimer);
   *   while (base->running_timer == mytimer);
   *
   * Now del_timer_sync() will never return and never release somelock.
   * The interrupt on the other CPU is waiting to grab somelock but
   * it has interrupted the softirq that CPU0 is waiting to finish.
   *
   * The function returns whether it has deactivated a pending timer or not.
   */
  int del_timer_sync(struct timer_list *timer)
  {
  #ifdef CONFIG_LOCKDEP
          unsigned long flags;
  
          /*
           * If lockdep gives a backtrace here, please reference
           * the synchronization rules above.
           */
          local_irq_save(flags);
          lock_map_acquire(&timer->lockdep_map);
          lock_map_release(&timer->lockdep_map);
          local_irq_restore(flags);
  #endif
          /*
           * don't use it in hardirq context, because it
           * could lead to deadlock.
           */
          WARN_ON(in_irq() && !tbase_get_irqsafe(timer->base));
          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(struct tvec_base *base, struct tvec *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);
                  /* No accounting, while moving them */
                  __internal_add_timer(base, timer);
          }
  
          return index;
  }
  
  static void call_timer_fn(struct timer_list *timer, void (*fn)(unsigned long),
                            unsigned long data)
  {
          int preempt_count = preempt_count();
  
  #ifdef CONFIG_LOCKDEP
          /*
           * It is permissible to free the timer from inside the
           * function that is called from it, this we need to take into
           * account for lockdep too. To avoid bogus "held lock freed"
           * warnings as well as problems when looking into
           * timer->lockdep_map, make a copy and use that here.
           */
          struct lockdep_map lockdep_map;
  
          lockdep_copy_map(&lockdep_map, &timer->lockdep_map);
  #endif
          /*
           * Couple the lock chain with the lock chain at
           * del_timer_sync() by acquiring the lock_map around the fn()
           * call here and in del_timer_sync().
           */
          lock_map_acquire(&lockdep_map);
  
          trace_timer_expire_entry(timer);
          fn(data);
          trace_timer_expire_exit(timer);
  
          lock_map_release(&lockdep_map);
  
          if (preempt_count != preempt_count()) {
                  WARN_ONCE(1, "timer: %pF preempt leak: %08x -> %08x\n",
                            fn, preempt_count, preempt_count());
                  /*
                   * Restore the preempt count. That gives us a decent
                   * chance to survive and extract information. If the
                   * callback kept a lock held, bad luck, but not worse
                   * than the BUG() we had.
                   */
                  preempt_count() = preempt_count;
          }
  }
  
  #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(struct tvec_base *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;
                          bool irqsafe;
  
                          timer = list_first_entry(head, struct timer_list,entry);
                          fn = timer->function;
                          data = timer->data;
                          irqsafe = tbase_get_irqsafe(timer->base);
  
                          timer_stats_account_timer(timer);
  
                          base->running_timer = timer;
                          detach_expired_timer(timer, base);
  
                          if (irqsafe) {
                                  spin_unlock(&base->lock);
                                  call_timer_fn(timer, fn, data);
                                  spin_lock(&base->lock);
                          } else {
                                  spin_unlock_irq(&base->lock);
                                  call_timer_fn(timer, fn, data);
                                  spin_lock_irq(&base->lock);
                          }
                  }
          }
          base->running_timer = NULL;
          spin_unlock_irq(&base->lock);
  }
  
  #ifdef 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 CPU is idle.
   * This function needs to be called with interrupts disabled.
   */
  static unsigned long __next_timer_interrupt(struct tvec_base *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;
          struct tvec *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++) {
                  struct tvec *varp = varray[array];
  
                  index = slot = timer_jiffies & TVN_MASK;
                  do {
                          list_for_each_entry(nte, varp->vec + slot, entry) {
                                  if (tbase_get_deferrable(nte->base))
                                          continue;
  
                                  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)
  {
          struct tvec_base *base = __this_cpu_read(tvec_bases);
          unsigned long expires = now + NEXT_TIMER_MAX_DELTA;
  
          /*
           * Pretend that there is no timer pending if the cpu is offline.
           * Possible pending timers will be migrated later to an active cpu.
           */
          if (cpu_is_offline(smp_processor_id()))
                  return expires;
  
          spin_lock(&base->lock);
          if (base->active_timers) {
                  if (time_before_eq(base->next_timer, base->timer_jiffies))
                          base->next_timer = __next_timer_interrupt(base);
                  expires = base->next_timer;
          }
          spin_unlock(&base->lock);
  
          if (time_before_eq(expires, now))
                  return now;
  
          return cmp_next_hrtimer_event(now, expires);
  }
  #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();
          rcu_check_callbacks(cpu, user_tick);
          printk_tick();
  #ifdef CONFIG_IRQ_WORK
          if (in_irq())
                  irq_work_run();
  #endif
          scheduler_tick();
          run_posix_cpu_timers(p);
  }
  
  /*
   * This function runs timers and the timer-tq in bottom half context.
   */
  static void run_timer_softirq(struct softirq_action *h)
  {
          struct tvec_base *base = __this_cpu_read(tvec_bases);
  
          hrtimer_run_pending();
  
          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)
  {
          hrtimer_run_queues();
          raise_softirq(TIMER_SOFTIRQ);
  }
  
  #ifdef __ARCH_WANT_SYS_ALARM
  
  /*
   * For backwards compatibility?  This can be done in libc so Alpha
   * and all newer ports shouldn't need it.
   */
  SYSCALL_DEFINE1(alarm, unsigned int, seconds)
  {
          return alarm_setitimer(seconds);
  }
  
  #endif
  
  /**
   * 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.
   */
  SYSCALL_DEFINE0(getpid)
  {
          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).
   */
  SYSCALL_DEFINE0(getppid)
  {
          int pid;
  
          rcu_read_lock();
          pid = task_tgid_vnr(rcu_dereference(current->real_parent));
          rcu_read_unlock();
  
          return pid;
  }
  
  SYSCALL_DEFINE0(getuid)
  {
          /* Only we change this so SMP safe */
          return from_kuid_munged(current_user_ns(), current_uid());
  }
  
  SYSCALL_DEFINE0(geteuid)
  {
          /* Only we change this so SMP safe */
          return from_kuid_munged(current_user_ns(), current_euid());
  }
  
  SYSCALL_DEFINE0(getgid)
  {
          /* Only we change this so SMP safe */
          return from_kgid_munged(current_user_ns(), current_gid());
  }
  
  SYSCALL_DEFINE0(getegid)
  {
          /* Only we change this so SMP safe */
          return from_kgid_munged(current_user_ns(), current_egid());
  }
  
  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.
   */
  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\n", timeout);
                          dump_stack();
                          current->state = TASK_RUNNING;
                          goto out;
                  }
          }
  
          expire = timeout + jiffies;
  
          setup_timer_on_stack(&timer, process_timeout, (unsigned long)current);
          __mod_timer(&timer, expire, false, TIMER_NOT_PINNED);
          schedule();
          del_singleshot_timer_sync(&timer);
  
          /* Remove the timer from the object tracker */
          destroy_timer_on_stack(&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_killable(signed long timeout)
  {
          __set_current_state(TASK_KILLABLE);
          return schedule_timeout(timeout);
  }
  EXPORT_SYMBOL(schedule_timeout_killable);
  
  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" */
  SYSCALL_DEFINE0(gettid)
  {
          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;
          struct timespec tp;
  
          memset(info, 0, sizeof(struct sysinfo));
  
          ktime_get_ts(&tp);
          monotonic_to_bootbased(&tp);
          info->uptime = tp.tv_sec + (tp.tv_nsec ? 1 : 0);
  
          get_avenrun(info->loads, 0, SI_LOAD_SHIFT - FSHIFT);
  
          info->procs = nr_threads;
  
          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;
  }
  
  SYSCALL_DEFINE1(sysinfo, struct sysinfo __user *, info)
  {
          struct sysinfo val;
  
          do_sysinfo(&val);
  
          if (copy_to_user(info, &val, sizeof(struct sysinfo)))
                  return -EFAULT;
  
          return 0;
  }
  
  static int __cpuinit init_timers_cpu(int cpu)
  {
          int j;
          struct tvec_base *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);
  
          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;
          base->next_timer = base->timer_jiffies;
          base->active_timers = 0;
          return 0;
  }
  
  #ifdef CONFIG_HOTPLUG_CPU
  static void migrate_timer_list(struct tvec_base *new_base, struct list_head *head)
  {
          struct timer_list *timer;
  
          while (!list_empty(head)) {
                  timer = list_first_entry(head, struct timer_list, entry);
                  /* We ignore the accounting on the dying cpu */
                  detach_timer(timer, false);
                  timer_set_base(timer, new_base);
                  internal_add_timer(new_base, timer);
          }
  }
  
  static void __cpuinit migrate_timers(int cpu)
  {
          struct tvec_base *old_base;
          struct tvec_base *new_base;
          int i;
  
          BUG_ON(cpu_online(cpu));
          old_base = per_cpu(tvec_bases, cpu);
          new_base = get_cpu_var(tvec_bases);
          /*
           * The caller is globally serialized and nobody else
           * takes two locks at once, deadlock is not possible.
           */
          spin_lock_irq(&new_base->lock);
          spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
  
          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);
          }
  
          spin_unlock(&old_base->lock);
          spin_unlock_irq(&new_base->lock);
          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;
          int err;
  
          switch(action) {
          case CPU_UP_PREPARE:
          case CPU_UP_PREPARE_FROZEN:
                  err = init_timers_cpu(cpu);
                  if (err < 0)
                          return notifier_from_errno(err);
                  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;
  
          /* ensure there are enough low bits for flags in timer->base pointer */
          BUILD_BUG_ON(__alignof__(struct tvec_base) & TIMER_FLAG_MASK);
  
          err = timer_cpu_notify(&timers_nb, (unsigned long)CPU_UP_PREPARE,
                                 (void *)(long)smp_processor_id());
          init_timer_stats();
  
          BUG_ON(err != NOTIFY_OK);
          register_cpu_notifier(&timers_nb);
          open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
  }
  
  /**
   * 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);
  
  static int __sched do_usleep_range(unsigned long min, unsigned long max)
  {
          ktime_t kmin;
          unsigned long delta;
  
          kmin = ktime_set(0, min * NSEC_PER_USEC);
          delta = (max - min) * NSEC_PER_USEC;
          return schedule_hrtimeout_range(&kmin, delta, HRTIMER_MODE_REL);
  }
  
  /**
   * usleep_range - Drop in replacement for udelay where wakeup is flexible
   * @min: Minimum time in usecs to sleep
   * @max: Maximum time in usecs to sleep
   */
  void usleep_range(unsigned long min, unsigned long max)
  {
          __set_current_state(TASK_UNINTERRUPTIBLE);
          do_usleep_range(min, max);
  }
  EXPORT_SYMBOL(usleep_range);

Cache object: dab0f4deefb06c556106515f401f164d