1 files changed, 1736 insertions, 0 deletions

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
new file mode 100644
index 000000000000..aca5dfe2fa3d
--- /dev/null
+++ b/kernel/time/timer.c
@@ -0,0 +1,1736 @@
+/*
+ *  linux/kernel/timer.c
+ *
+ *  Kernel internal timers
+ *
+ *  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/sched/sysctl.h>
+#include <linux/slab.h>
+#include <linux/compat.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>
+
+__visible 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;
+        unsigned long all_timers;
+        int cpu;
+        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;
+
+        /*
+         * Make sure j is still in the future. Otherwise return the
+         * unmodified value.
+         */
+        return time_is_after_jiffies(j) ? j : original;
+}
+
+/**
+ * __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);
+
+/*
+ * If the list is empty, catch up ->timer_jiffies to the current time.
+ * The caller must hold the tvec_base lock.  Returns true if the list
+ * was empty and therefore ->timer_jiffies was updated.
+ */
+static bool catchup_timer_jiffies(struct tvec_base *base)
+{
+        if (!base->all_timers) {
+                base->timer_jiffies = jiffies;
+                return true;
+        }
+        return false;
+}
+
+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)
+{
+        (void)catchup_timer_jiffies(base);
+        __internal_add_timer(base, timer);
+        /*
+         * Update base->active_timers and base->next_timer
+         */
+        if (!tbase_get_deferrable(timer->base)) {
+                if (!base->active_timers++ ||
+                    time_before(timer->expires, base->next_timer))
+                        base->next_timer = timer->expires;
+        }
+        base->all_timers++;
+
+        /*
+         * Check whether the other CPU is in dynticks mode and needs
+         * to be triggered to reevaluate the timer wheel.
+         * 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 stop its tick can not
+         * evaluate the timer wheel.
+         *
+         * Spare the IPI for deferrable timers on idle targets though.
+         * The next busy ticks will take care of it. Except full dynticks
+         * require special care against races with idle_cpu(), lets deal
+         * with that later.
+         */
+        if (!tbase_get_deferrable(base) || tick_nohz_full_cpu(base->cpu))
+                wake_up_nohz_cpu(base->cpu);
+}
+
+#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--;
+        base->all_timers--;
+        (void)catchup_timer_jiffies(base);
+}
+
+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;
+        }
+        base->all_timers--;
+        (void)catchup_timer_jiffies(base);
+        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 = get_nohz_timer_target(pinned);
+        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 = (1UL << 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);
+        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 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 (count != preempt_count()) {
+                WARN_ONCE(1, "timer: %pF preempt leak: %08x -> %08x\n",
+                          fn, 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_set(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);
+        if (catchup_timer_jiffies(base)) {
+                spin_unlock_irq(&base->lock);
+                return;
+        }
+        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, head);
+                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_COMMON
+/*
+ * 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);
+#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
+
+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);
+
+static int init_timers_cpu(int cpu)
+{
+        int j;
+        struct tvec_base *base;
+        static char 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 = kzalloc_node(sizeof(*base), GFP_KERNEL,
+                                            cpu_to_node(cpu));
+                        if (!base)
+                                return -ENOMEM;
+
+                        /* Make sure tvec_base has TIMER_FLAG_MASK bits free */
+                        if (WARN_ON(base != tbase_get_base(base))) {
+                                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;
+                }
+                spin_lock_init(&base->lock);
+                tvec_base_done[cpu] = 1;
+                base->cpu = cpu;
+        } else {
+                base = per_cpu(tvec_bases, 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;
+        base->next_timer = base->timer_jiffies;
+        base->active_timers = 0;
+        base->all_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 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 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 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());
+        BUG_ON(err != NOTIFY_OK);
+
+        init_timer_stats();
+        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);