time/timers: Move all time(r) related files into kernel/time

Except for Kconfig.HZ. That needs a separate treatment.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 1915 insertions, 0 deletions

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
new file mode 100644
index 000000000000..3ab28993f6e0
--- /dev/null
+++ b/kernel/time/hrtimer.c
@@ -0,0 +1,1915 @@
+/*
+ *  linux/kernel/hrtimer.c
+ *
+ *  Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
+ *  Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
+ *  Copyright(C) 2006-2007  Timesys Corp., Thomas Gleixner
+ *
+ *  High-resolution kernel timers
+ *
+ *  In contrast to the low-resolution timeout API implemented in
+ *  kernel/timer.c, hrtimers provide finer resolution and accuracy
+ *  depending on system configuration and capabilities.
+ *
+ *  These timers are currently used for:
+ *   - itimers
+ *   - POSIX timers
+ *   - nanosleep
+ *   - precise in-kernel timing
+ *
+ *  Started by: Thomas Gleixner and Ingo Molnar
+ *
+ *  Credits:
+ *      based on kernel/timer.c
+ *
+ *      Help, testing, suggestions, bugfixes, improvements were
+ *      provided by:
+ *
+ *      George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
+ *      et. al.
+ *
+ *  For licencing details see kernel-base/COPYING
+ */
+
+#include <linux/cpu.h>
+#include <linux/export.h>
+#include <linux/percpu.h>
+#include <linux/hrtimer.h>
+#include <linux/notifier.h>
+#include <linux/syscalls.h>
+#include <linux/kallsyms.h>
+#include <linux/interrupt.h>
+#include <linux/tick.h>
+#include <linux/seq_file.h>
+#include <linux/err.h>
+#include <linux/debugobjects.h>
+#include <linux/sched.h>
+#include <linux/sched/sysctl.h>
+#include <linux/sched/rt.h>
+#include <linux/sched/deadline.h>
+#include <linux/timer.h>
+#include <linux/freezer.h>
+
+#include <asm/uaccess.h>
+
+#include <trace/events/timer.h>
+
+/*
+ * The timer bases:
+ *
+ * There are more clockids then hrtimer bases. Thus, we index
+ * into the timer bases by the hrtimer_base_type enum. When trying
+ * to reach a base using a clockid, hrtimer_clockid_to_base()
+ * is used to convert from clockid to the proper hrtimer_base_type.
+ */
+DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
+{
+
+        .lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
+        .clock_base =
+        {
+                {
+                        .index = HRTIMER_BASE_MONOTONIC,
+                        .clockid = CLOCK_MONOTONIC,
+                        .get_time = &ktime_get,
+                        .resolution = KTIME_LOW_RES,
+                },
+                {
+                        .index = HRTIMER_BASE_REALTIME,
+                        .clockid = CLOCK_REALTIME,
+                        .get_time = &ktime_get_real,
+                        .resolution = KTIME_LOW_RES,
+                },
+                {
+                        .index = HRTIMER_BASE_BOOTTIME,
+                        .clockid = CLOCK_BOOTTIME,
+                        .get_time = &ktime_get_boottime,
+                        .resolution = KTIME_LOW_RES,
+                },
+                {
+                        .index = HRTIMER_BASE_TAI,
+                        .clockid = CLOCK_TAI,
+                        .get_time = &ktime_get_clocktai,
+                        .resolution = KTIME_LOW_RES,
+                },
+        }
+};
+
+static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
+        [CLOCK_REALTIME]        = HRTIMER_BASE_REALTIME,
+        [CLOCK_MONOTONIC]       = HRTIMER_BASE_MONOTONIC,
+        [CLOCK_BOOTTIME]        = HRTIMER_BASE_BOOTTIME,
+        [CLOCK_TAI]             = HRTIMER_BASE_TAI,
+};
+
+static inline int hrtimer_clockid_to_base(clockid_t clock_id)
+{
+        return hrtimer_clock_to_base_table[clock_id];
+}
+
+
+/*
+ * Get the coarse grained time at the softirq based on xtime and
+ * wall_to_monotonic.
+ */
+static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base)
+{
+        ktime_t xtim, mono, boot;
+        struct timespec xts, tom, slp;
+        s32 tai_offset;
+
+        get_xtime_and_monotonic_and_sleep_offset(&xts, &tom, &slp);
+        tai_offset = timekeeping_get_tai_offset();
+
+        xtim = timespec_to_ktime(xts);
+        mono = ktime_add(xtim, timespec_to_ktime(tom));
+        boot = ktime_add(mono, timespec_to_ktime(slp));
+        base->clock_base[HRTIMER_BASE_REALTIME].softirq_time = xtim;
+        base->clock_base[HRTIMER_BASE_MONOTONIC].softirq_time = mono;
+        base->clock_base[HRTIMER_BASE_BOOTTIME].softirq_time = boot;
+        base->clock_base[HRTIMER_BASE_TAI].softirq_time =
+                                ktime_add(xtim, ktime_set(tai_offset, 0));
+}
+
+/*
+ * Functions and macros which are different for UP/SMP systems are kept in a
+ * single place
+ */
+#ifdef CONFIG_SMP
+
+/*
+ * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
+ * means that all timers which are tied to this base via timer->base are
+ * locked, and the base itself is locked too.
+ *
+ * So __run_timers/migrate_timers can safely modify all timers which could
+ * be found on the lists/queues.
+ *
+ * When the timer's base is locked, and the timer removed from list, it is
+ * possible to set timer->base = NULL and drop the lock: the timer remains
+ * locked.
+ */
+static
+struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
+                                             unsigned long *flags)
+{
+        struct hrtimer_clock_base *base;
+
+        for (;;) {
+                base = timer->base;
+                if (likely(base != NULL)) {
+                        raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
+                        if (likely(base == timer->base))
+                                return base;
+                        /* The timer has migrated to another CPU: */
+                        raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
+                }
+                cpu_relax();
+        }
+}
+
+/*
+ * With HIGHRES=y we do not migrate the timer when it is expiring
+ * before the next event on the target cpu because we cannot reprogram
+ * the target cpu hardware and we would cause it to fire late.
+ *
+ * Called with cpu_base->lock of target cpu held.
+ */
+static int
+hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
+{
+#ifdef CONFIG_HIGH_RES_TIMERS
+        ktime_t expires;
+
+        if (!new_base->cpu_base->hres_active)
+                return 0;
+
+        expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
+        return expires.tv64 <= new_base->cpu_base->expires_next.tv64;
+#else
+        return 0;
+#endif
+}
+
+/*
+ * Switch the timer base to the current CPU when possible.
+ */
+static inline struct hrtimer_clock_base *
+switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
+                    int pinned)
+{
+        struct hrtimer_clock_base *new_base;
+        struct hrtimer_cpu_base *new_cpu_base;
+        int this_cpu = smp_processor_id();
+        int cpu = get_nohz_timer_target(pinned);
+        int basenum = base->index;
+
+again:
+        new_cpu_base = &per_cpu(hrtimer_bases, cpu);
+        new_base = &new_cpu_base->clock_base[basenum];
+
+        if (base != new_base) {
+                /*
+                 * We are trying to move timer to new_base.
+                 * However we can't change timer's base while it is running,
+                 * so we keep it on the same CPU. No hassle vs. reprogramming
+                 * the event source in the high resolution case. The softirq
+                 * code will take care of this when the timer function has
+                 * completed. There is no conflict as we hold the lock until
+                 * the timer is enqueued.
+                 */
+                if (unlikely(hrtimer_callback_running(timer)))
+                        return base;
+
+                /* See the comment in lock_timer_base() */
+                timer->base = NULL;
+                raw_spin_unlock(&base->cpu_base->lock);
+                raw_spin_lock(&new_base->cpu_base->lock);
+
+                if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
+                        cpu = this_cpu;
+                        raw_spin_unlock(&new_base->cpu_base->lock);
+                        raw_spin_lock(&base->cpu_base->lock);
+                        timer->base = base;
+                        goto again;
+                }
+                timer->base = new_base;
+        } else {
+                if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
+                        cpu = this_cpu;
+                        goto again;
+                }
+        }
+        return new_base;
+}
+
+#else /* CONFIG_SMP */
+
+static inline struct hrtimer_clock_base *
+lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
+{
+        struct hrtimer_clock_base *base = timer->base;
+
+        raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
+
+        return base;
+}
+
+# define switch_hrtimer_base(t, b, p)   (b)
+
+#endif  /* !CONFIG_SMP */
+
+/*
+ * Functions for the union type storage format of ktime_t which are
+ * too large for inlining:
+ */
+#if BITS_PER_LONG < 64
+# ifndef CONFIG_KTIME_SCALAR
+/**
+ * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
+ * @kt:         addend
+ * @nsec:       the scalar nsec value to add
+ *
+ * Returns the sum of kt and nsec in ktime_t format
+ */
+ktime_t ktime_add_ns(const ktime_t kt, u64 nsec)
+{
+        ktime_t tmp;
+
+        if (likely(nsec < NSEC_PER_SEC)) {
+                tmp.tv64 = nsec;
+        } else {
+                unsigned long rem = do_div(nsec, NSEC_PER_SEC);
+
+                /* Make sure nsec fits into long */
+                if (unlikely(nsec > KTIME_SEC_MAX))
+                        return (ktime_t){ .tv64 = KTIME_MAX };
+
+                tmp = ktime_set((long)nsec, rem);
+        }
+
+        return ktime_add(kt, tmp);
+}
+
+EXPORT_SYMBOL_GPL(ktime_add_ns);
+
+/**
+ * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
+ * @kt:         minuend
+ * @nsec:       the scalar nsec value to subtract
+ *
+ * Returns the subtraction of @nsec from @kt in ktime_t format
+ */
+ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec)
+{
+        ktime_t tmp;
+
+        if (likely(nsec < NSEC_PER_SEC)) {
+                tmp.tv64 = nsec;
+        } else {
+                unsigned long rem = do_div(nsec, NSEC_PER_SEC);
+
+                tmp = ktime_set((long)nsec, rem);
+        }
+
+        return ktime_sub(kt, tmp);
+}
+
+EXPORT_SYMBOL_GPL(ktime_sub_ns);
+# endif /* !CONFIG_KTIME_SCALAR */
+
+/*
+ * Divide a ktime value by a nanosecond value
+ */
+u64 ktime_divns(const ktime_t kt, s64 div)
+{
+        u64 dclc;
+        int sft = 0;
+
+        dclc = ktime_to_ns(kt);
+        /* Make sure the divisor is less than 2^32: */
+        while (div >> 32) {
+                sft++;
+                div >>= 1;
+        }
+        dclc >>= sft;
+        do_div(dclc, (unsigned long) div);
+
+        return dclc;
+}
+#endif /* BITS_PER_LONG >= 64 */
+
+/*
+ * Add two ktime values and do a safety check for overflow:
+ */
+ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
+{
+        ktime_t res = ktime_add(lhs, rhs);
+
+        /*
+         * We use KTIME_SEC_MAX here, the maximum timeout which we can
+         * return to user space in a timespec:
+         */
+        if (res.tv64 < 0 || res.tv64 < lhs.tv64 || res.tv64 < rhs.tv64)
+                res = ktime_set(KTIME_SEC_MAX, 0);
+
+        return res;
+}
+
+EXPORT_SYMBOL_GPL(ktime_add_safe);
+
+#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
+
+static struct debug_obj_descr hrtimer_debug_descr;
+
+static void *hrtimer_debug_hint(void *addr)
+{
+        return ((struct hrtimer *) addr)->function;
+}
+
+/*
+ * fixup_init is called when:
+ * - an active object is initialized
+ */
+static int hrtimer_fixup_init(void *addr, enum debug_obj_state state)
+{
+        struct hrtimer *timer = addr;
+
+        switch (state) {
+        case ODEBUG_STATE_ACTIVE:
+                hrtimer_cancel(timer);
+                debug_object_init(timer, &hrtimer_debug_descr);
+                return 1;
+        default:
+                return 0;
+        }
+}
+
+/*
+ * fixup_activate is called when:
+ * - an active object is activated
+ * - an unknown object is activated (might be a statically initialized object)
+ */
+static int hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
+{
+        switch (state) {
+
+        case ODEBUG_STATE_NOTAVAILABLE:
+                WARN_ON_ONCE(1);
+                return 0;
+
+        case ODEBUG_STATE_ACTIVE:
+                WARN_ON(1);
+
+        default:
+                return 0;
+        }
+}
+
+/*
+ * fixup_free is called when:
+ * - an active object is freed
+ */
+static int hrtimer_fixup_free(void *addr, enum debug_obj_state state)
+{
+        struct hrtimer *timer = addr;
+
+        switch (state) {
+        case ODEBUG_STATE_ACTIVE:
+                hrtimer_cancel(timer);
+                debug_object_free(timer, &hrtimer_debug_descr);
+                return 1;
+        default:
+                return 0;
+        }
+}
+
+static struct debug_obj_descr hrtimer_debug_descr = {
+        .name           = "hrtimer",
+        .debug_hint     = hrtimer_debug_hint,
+        .fixup_init     = hrtimer_fixup_init,
+        .fixup_activate = hrtimer_fixup_activate,
+        .fixup_free     = hrtimer_fixup_free,
+};
+
+static inline void debug_hrtimer_init(struct hrtimer *timer)
+{
+        debug_object_init(timer, &hrtimer_debug_descr);
+}
+
+static inline void debug_hrtimer_activate(struct hrtimer *timer)
+{
+        debug_object_activate(timer, &hrtimer_debug_descr);
+}
+
+static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
+{
+        debug_object_deactivate(timer, &hrtimer_debug_descr);
+}
+
+static inline void debug_hrtimer_free(struct hrtimer *timer)
+{
+        debug_object_free(timer, &hrtimer_debug_descr);
+}
+
+static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
+                           enum hrtimer_mode mode);
+
+void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
+                           enum hrtimer_mode mode)
+{
+        debug_object_init_on_stack(timer, &hrtimer_debug_descr);
+        __hrtimer_init(timer, clock_id, mode);
+}
+EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
+
+void destroy_hrtimer_on_stack(struct hrtimer *timer)
+{
+        debug_object_free(timer, &hrtimer_debug_descr);
+}
+
+#else
+static inline void debug_hrtimer_init(struct hrtimer *timer) { }
+static inline void debug_hrtimer_activate(struct hrtimer *timer) { }
+static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
+#endif
+
+static inline void
+debug_init(struct hrtimer *timer, clockid_t clockid,
+           enum hrtimer_mode mode)
+{
+        debug_hrtimer_init(timer);
+        trace_hrtimer_init(timer, clockid, mode);
+}
+
+static inline void debug_activate(struct hrtimer *timer)
+{
+        debug_hrtimer_activate(timer);
+        trace_hrtimer_start(timer);
+}
+
+static inline void debug_deactivate(struct hrtimer *timer)
+{
+        debug_hrtimer_deactivate(timer);
+        trace_hrtimer_cancel(timer);
+}
+
+/* High resolution timer related functions */
+#ifdef CONFIG_HIGH_RES_TIMERS
+
+/*
+ * High resolution timer enabled ?
+ */
+static int hrtimer_hres_enabled __read_mostly  = 1;
+
+/*
+ * Enable / Disable high resolution mode
+ */
+static int __init setup_hrtimer_hres(char *str)
+{
+        if (!strcmp(str, "off"))
+                hrtimer_hres_enabled = 0;
+        else if (!strcmp(str, "on"))
+                hrtimer_hres_enabled = 1;
+        else
+                return 0;
+        return 1;
+}
+
+__setup("highres=", setup_hrtimer_hres);
+
+/*
+ * hrtimer_high_res_enabled - query, if the highres mode is enabled
+ */
+static inline int hrtimer_is_hres_enabled(void)
+{
+        return hrtimer_hres_enabled;
+}
+
+/*
+ * Is the high resolution mode active ?
+ */
+static inline int hrtimer_hres_active(void)
+{
+        return __this_cpu_read(hrtimer_bases.hres_active);
+}
+
+/*
+ * Reprogram the event source with checking both queues for the
+ * next event
+ * Called with interrupts disabled and base->lock held
+ */
+static void
+hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
+{
+        int i;
+        struct hrtimer_clock_base *base = cpu_base->clock_base;
+        ktime_t expires, expires_next;
+
+        expires_next.tv64 = KTIME_MAX;
+
+        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
+                struct hrtimer *timer;
+                struct timerqueue_node *next;
+
+                next = timerqueue_getnext(&base->active);
+                if (!next)
+                        continue;
+                timer = container_of(next, struct hrtimer, node);
+
+                expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
+                /*
+                 * clock_was_set() has changed base->offset so the
+                 * result might be negative. Fix it up to prevent a
+                 * false positive in clockevents_program_event()
+                 */
+                if (expires.tv64 < 0)
+                        expires.tv64 = 0;
+                if (expires.tv64 < expires_next.tv64)
+                        expires_next = expires;
+        }
+
+        if (skip_equal && expires_next.tv64 == cpu_base->expires_next.tv64)
+                return;
+
+        cpu_base->expires_next.tv64 = expires_next.tv64;
+
+        /*
+         * If a hang was detected in the last timer interrupt then we
+         * leave the hang delay active in the hardware. We want the
+         * system to make progress. That also prevents the following
+         * scenario:
+         * T1 expires 50ms from now
+         * T2 expires 5s from now
+         *
+         * T1 is removed, so this code is called and would reprogram
+         * the hardware to 5s from now. Any hrtimer_start after that
+         * will not reprogram the hardware due to hang_detected being
+         * set. So we'd effectivly block all timers until the T2 event
+         * fires.
+         */
+        if (cpu_base->hang_detected)
+                return;
+
+        if (cpu_base->expires_next.tv64 != KTIME_MAX)
+                tick_program_event(cpu_base->expires_next, 1);
+}
+
+/*
+ * Shared reprogramming for clock_realtime and clock_monotonic
+ *
+ * When a timer is enqueued and expires earlier than the already enqueued
+ * timers, we have to check, whether it expires earlier than the timer for
+ * which the clock event device was armed.
+ *
+ * Called with interrupts disabled and base->cpu_base.lock held
+ */
+static int hrtimer_reprogram(struct hrtimer *timer,
+                             struct hrtimer_clock_base *base)
+{
+        struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
+        ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
+        int res;
+
+        WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
+
+        /*
+         * When the callback is running, we do not reprogram the clock event
+         * device. The timer callback is either running on a different CPU or
+         * the callback is executed in the hrtimer_interrupt context. The
+         * reprogramming is handled either by the softirq, which called the
+         * callback or at the end of the hrtimer_interrupt.
+         */
+        if (hrtimer_callback_running(timer))
+                return 0;
+
+        /*
+         * CLOCK_REALTIME timer might be requested with an absolute
+         * expiry time which is less than base->offset. Nothing wrong
+         * about that, just avoid to call into the tick code, which
+         * has now objections against negative expiry values.
+         */
+        if (expires.tv64 < 0)
+                return -ETIME;
+
+        if (expires.tv64 >= cpu_base->expires_next.tv64)
+                return 0;
+
+        /*
+         * If a hang was detected in the last timer interrupt then we
+         * do not schedule a timer which is earlier than the expiry
+         * which we enforced in the hang detection. We want the system
+         * to make progress.
+         */
+        if (cpu_base->hang_detected)
+                return 0;
+
+        /*
+         * Clockevents returns -ETIME, when the event was in the past.
+         */
+        res = tick_program_event(expires, 0);
+        if (!IS_ERR_VALUE(res))
+                cpu_base->expires_next = expires;
+        return res;
+}
+
+/*
+ * Initialize the high resolution related parts of cpu_base
+ */
+static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
+{
+        base->expires_next.tv64 = KTIME_MAX;
+        base->hres_active = 0;
+}
+
+/*
+ * When High resolution timers are active, try to reprogram. Note, that in case
+ * the state has HRTIMER_STATE_CALLBACK set, no reprogramming and no expiry
+ * check happens. The timer gets enqueued into the rbtree. The reprogramming
+ * and expiry check is done in the hrtimer_interrupt or in the softirq.
+ */
+static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
+                                            struct hrtimer_clock_base *base)
+{
+        return base->cpu_base->hres_active && hrtimer_reprogram(timer, base);
+}
+
+static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
+{
+        ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
+        ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
+        ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
+
+        return ktime_get_update_offsets(offs_real, offs_boot, offs_tai);
+}
+
+/*
+ * Retrigger next event is called after clock was set
+ *
+ * Called with interrupts disabled via on_each_cpu()
+ */
+static void retrigger_next_event(void *arg)
+{
+        struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases);
+
+        if (!hrtimer_hres_active())
+                return;
+
+        raw_spin_lock(&base->lock);
+        hrtimer_update_base(base);
+        hrtimer_force_reprogram(base, 0);
+        raw_spin_unlock(&base->lock);
+}
+
+/*
+ * Switch to high resolution mode
+ */
+static int hrtimer_switch_to_hres(void)
+{
+        int i, cpu = smp_processor_id();
+        struct hrtimer_cpu_base *base = &per_cpu(hrtimer_bases, cpu);
+        unsigned long flags;
+
+        if (base->hres_active)
+                return 1;
+
+        local_irq_save(flags);
+
+        if (tick_init_highres()) {
+                local_irq_restore(flags);
+                printk(KERN_WARNING "Could not switch to high resolution "
+                                    "mode on CPU %d\n", cpu);
+                return 0;
+        }
+        base->hres_active = 1;
+        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)
+                base->clock_base[i].resolution = KTIME_HIGH_RES;
+
+        tick_setup_sched_timer();
+        /* "Retrigger" the interrupt to get things going */
+        retrigger_next_event(NULL);
+        local_irq_restore(flags);
+        return 1;
+}
+
+static void clock_was_set_work(struct work_struct *work)
+{
+        clock_was_set();
+}
+
+static DECLARE_WORK(hrtimer_work, clock_was_set_work);
+
+/*
+ * Called from timekeeping and resume code to reprogramm the hrtimer
+ * interrupt device on all cpus.
+ */
+void clock_was_set_delayed(void)
+{
+        schedule_work(&hrtimer_work);
+}
+
+#else
+
+static inline int hrtimer_hres_active(void) { return 0; }
+static inline int hrtimer_is_hres_enabled(void) { return 0; }
+static inline int hrtimer_switch_to_hres(void) { return 0; }
+static inline void
+hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
+static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
+                                            struct hrtimer_clock_base *base)
+{
+        return 0;
+}
+static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
+static inline void retrigger_next_event(void *arg) { }
+
+#endif /* CONFIG_HIGH_RES_TIMERS */
+
+/*
+ * Clock realtime was set
+ *
+ * Change the offset of the realtime clock vs. the monotonic
+ * clock.
+ *
+ * We might have to reprogram the high resolution timer interrupt. On
+ * SMP we call the architecture specific code to retrigger _all_ high
+ * resolution timer interrupts. On UP we just disable interrupts and
+ * call the high resolution interrupt code.
+ */
+void clock_was_set(void)
+{
+#ifdef CONFIG_HIGH_RES_TIMERS
+        /* Retrigger the CPU local events everywhere */
+        on_each_cpu(retrigger_next_event, NULL, 1);
+#endif
+        timerfd_clock_was_set();
+}
+
+/*
+ * During resume we might have to reprogram the high resolution timer
+ * interrupt on all online CPUs.  However, all other CPUs will be
+ * stopped with IRQs interrupts disabled so the clock_was_set() call
+ * must be deferred.
+ */
+void hrtimers_resume(void)
+{
+        WARN_ONCE(!irqs_disabled(),
+                  KERN_INFO "hrtimers_resume() called with IRQs enabled!");
+
+        /* Retrigger on the local CPU */
+        retrigger_next_event(NULL);
+        /* And schedule a retrigger for all others */
+        clock_was_set_delayed();
+}
+
+static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
+{
+#ifdef CONFIG_TIMER_STATS
+        if (timer->start_site)
+                return;
+        timer->start_site = __builtin_return_address(0);
+        memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
+        timer->start_pid = current->pid;
+#endif
+}
+
+static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
+{
+#ifdef CONFIG_TIMER_STATS
+        timer->start_site = NULL;
+#endif
+}
+
+static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
+{
+#ifdef CONFIG_TIMER_STATS
+        if (likely(!timer_stats_active))
+                return;
+        timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
+                                 timer->function, timer->start_comm, 0);
+#endif
+}
+
+/*
+ * Counterpart to lock_hrtimer_base above:
+ */
+static inline
+void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
+{
+        raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
+}
+
+/**
+ * hrtimer_forward - forward the timer expiry
+ * @timer:      hrtimer to forward
+ * @now:        forward past this time
+ * @interval:   the interval to forward
+ *
+ * Forward the timer expiry so it will expire in the future.
+ * Returns the number of overruns.
+ */
+u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
+{
+        u64 orun = 1;
+        ktime_t delta;
+
+        delta = ktime_sub(now, hrtimer_get_expires(timer));
+
+        if (delta.tv64 < 0)
+                return 0;
+
+        if (interval.tv64 < timer->base->resolution.tv64)
+                interval.tv64 = timer->base->resolution.tv64;
+
+        if (unlikely(delta.tv64 >= interval.tv64)) {
+                s64 incr = ktime_to_ns(interval);
+
+                orun = ktime_divns(delta, incr);
+                hrtimer_add_expires_ns(timer, incr * orun);
+                if (hrtimer_get_expires_tv64(timer) > now.tv64)
+                        return orun;
+                /*
+                 * This (and the ktime_add() below) is the
+                 * correction for exact:
+                 */
+                orun++;
+        }
+        hrtimer_add_expires(timer, interval);
+
+        return orun;
+}
+EXPORT_SYMBOL_GPL(hrtimer_forward);
+
+/*
+ * enqueue_hrtimer - internal function to (re)start a timer
+ *
+ * The timer is inserted in expiry order. Insertion into the
+ * red black tree is O(log(n)). Must hold the base lock.
+ *
+ * Returns 1 when the new timer is the leftmost timer in the tree.
+ */
+static int enqueue_hrtimer(struct hrtimer *timer,
+                           struct hrtimer_clock_base *base)
+{
+        debug_activate(timer);
+
+        timerqueue_add(&base->active, &timer->node);
+        base->cpu_base->active_bases |= 1 << base->index;
+
+        /*
+         * HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the
+         * state of a possibly running callback.
+         */
+        timer->state |= HRTIMER_STATE_ENQUEUED;
+
+        return (&timer->node == base->active.next);
+}
+
+/*
+ * __remove_hrtimer - internal function to remove a timer
+ *
+ * Caller must hold the base lock.
+ *
+ * High resolution timer mode reprograms the clock event device when the
+ * timer is the one which expires next. The caller can disable this by setting
+ * reprogram to zero. This is useful, when the context does a reprogramming
+ * anyway (e.g. timer interrupt)
+ */
+static void __remove_hrtimer(struct hrtimer *timer,
+                             struct hrtimer_clock_base *base,
+                             unsigned long newstate, int reprogram)
+{
+        struct timerqueue_node *next_timer;
+        if (!(timer->state & HRTIMER_STATE_ENQUEUED))
+                goto out;
+
+        next_timer = timerqueue_getnext(&base->active);
+        timerqueue_del(&base->active, &timer->node);
+        if (&timer->node == next_timer) {
+#ifdef CONFIG_HIGH_RES_TIMERS
+                /* Reprogram the clock event device. if enabled */
+                if (reprogram && hrtimer_hres_active()) {
+                        ktime_t expires;
+
+                        expires = ktime_sub(hrtimer_get_expires(timer),
+                                            base->offset);
+                        if (base->cpu_base->expires_next.tv64 == expires.tv64)
+                                hrtimer_force_reprogram(base->cpu_base, 1);
+                }
+#endif
+        }
+        if (!timerqueue_getnext(&base->active))
+                base->cpu_base->active_bases &= ~(1 << base->index);
+out:
+        timer->state = newstate;
+}
+
+/*
+ * remove hrtimer, called with base lock held
+ */
+static inline int
+remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
+{
+        if (hrtimer_is_queued(timer)) {
+                unsigned long state;
+                int reprogram;
+
+                /*
+                 * Remove the timer and force reprogramming when high
+                 * resolution mode is active and the timer is on the current
+                 * CPU. If we remove a timer on another CPU, reprogramming is
+                 * skipped. The interrupt event on this CPU is fired and
+                 * reprogramming happens in the interrupt handler. This is a
+                 * rare case and less expensive than a smp call.
+                 */
+                debug_deactivate(timer);
+                timer_stats_hrtimer_clear_start_info(timer);
+                reprogram = base->cpu_base == &__get_cpu_var(hrtimer_bases);
+                /*
+                 * We must preserve the CALLBACK state flag here,
+                 * otherwise we could move the timer base in
+                 * switch_hrtimer_base.
+                 */
+                state = timer->state & HRTIMER_STATE_CALLBACK;
+                __remove_hrtimer(timer, base, state, reprogram);
+                return 1;
+        }
+        return 0;
+}
+
+int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
+                unsigned long delta_ns, const enum hrtimer_mode mode,
+                int wakeup)
+{
+        struct hrtimer_clock_base *base, *new_base;
+        unsigned long flags;
+        int ret, leftmost;
+
+        base = lock_hrtimer_base(timer, &flags);
+
+        /* Remove an active timer from the queue: */
+        ret = remove_hrtimer(timer, base);
+
+        if (mode & HRTIMER_MODE_REL) {
+                tim = ktime_add_safe(tim, base->get_time());
+                /*
+                 * CONFIG_TIME_LOW_RES is a temporary way for architectures
+                 * to signal that they simply return xtime in
+                 * do_gettimeoffset(). In this case we want to round up by
+                 * resolution when starting a relative timer, to avoid short
+                 * timeouts. This will go away with the GTOD framework.
+                 */
+#ifdef CONFIG_TIME_LOW_RES
+                tim = ktime_add_safe(tim, base->resolution);
+#endif
+        }
+
+        hrtimer_set_expires_range_ns(timer, tim, delta_ns);
+
+        /* Switch the timer base, if necessary: */
+        new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
+
+        timer_stats_hrtimer_set_start_info(timer);
+
+        leftmost = enqueue_hrtimer(timer, new_base);
+
+        /*
+         * Only allow reprogramming if the new base is on this CPU.
+         * (it might still be on another CPU if the timer was pending)
+         *
+         * XXX send_remote_softirq() ?
+         */
+        if (leftmost && new_base->cpu_base == &__get_cpu_var(hrtimer_bases)
+                && hrtimer_enqueue_reprogram(timer, new_base)) {
+                if (wakeup) {
+                        /*
+                         * We need to drop cpu_base->lock to avoid a
+                         * lock ordering issue vs. rq->lock.
+                         */
+                        raw_spin_unlock(&new_base->cpu_base->lock);
+                        raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+                        local_irq_restore(flags);
+                        return ret;
+                } else {
+                        __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
+                }
+        }
+
+        unlock_hrtimer_base(timer, &flags);
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(__hrtimer_start_range_ns);
+
+/**
+ * hrtimer_start_range_ns - (re)start an hrtimer on the current CPU
+ * @timer:      the timer to be added
+ * @tim:        expiry time
+ * @delta_ns:   "slack" range for the timer
+ * @mode:       expiry mode: absolute (HRTIMER_MODE_ABS) or
+ *              relative (HRTIMER_MODE_REL)
+ *
+ * Returns:
+ *  0 on success
+ *  1 when the timer was active
+ */
+int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
+                unsigned long delta_ns, const enum hrtimer_mode mode)
+{
+        return __hrtimer_start_range_ns(timer, tim, delta_ns, mode, 1);
+}
+EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
+
+/**
+ * hrtimer_start - (re)start an hrtimer on the current CPU
+ * @timer:      the timer to be added
+ * @tim:        expiry time
+ * @mode:       expiry mode: absolute (HRTIMER_MODE_ABS) or
+ *              relative (HRTIMER_MODE_REL)
+ *
+ * Returns:
+ *  0 on success
+ *  1 when the timer was active
+ */
+int
+hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
+{
+        return __hrtimer_start_range_ns(timer, tim, 0, mode, 1);
+}
+EXPORT_SYMBOL_GPL(hrtimer_start);
+
+
+/**
+ * hrtimer_try_to_cancel - try to deactivate a timer
+ * @timer:      hrtimer to stop
+ *
+ * Returns:
+ *  0 when the timer was not active
+ *  1 when the timer was active
+ * -1 when the timer is currently excuting the callback function and
+ *    cannot be stopped
+ */
+int hrtimer_try_to_cancel(struct hrtimer *timer)
+{
+        struct hrtimer_clock_base *base;
+        unsigned long flags;
+        int ret = -1;
+
+        base = lock_hrtimer_base(timer, &flags);
+
+        if (!hrtimer_callback_running(timer))
+                ret = remove_hrtimer(timer, base);
+
+        unlock_hrtimer_base(timer, &flags);
+
+        return ret;
+
+}
+EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
+
+/**
+ * hrtimer_cancel - cancel a timer and wait for the handler to finish.
+ * @timer:      the timer to be cancelled
+ *
+ * Returns:
+ *  0 when the timer was not active
+ *  1 when the timer was active
+ */
+int hrtimer_cancel(struct hrtimer *timer)
+{
+        for (;;) {
+                int ret = hrtimer_try_to_cancel(timer);
+
+                if (ret >= 0)
+                        return ret;
+                cpu_relax();
+        }
+}
+EXPORT_SYMBOL_GPL(hrtimer_cancel);
+
+/**
+ * hrtimer_get_remaining - get remaining time for the timer
+ * @timer:      the timer to read
+ */
+ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
+{
+        unsigned long flags;
+        ktime_t rem;
+
+        lock_hrtimer_base(timer, &flags);
+        rem = hrtimer_expires_remaining(timer);
+        unlock_hrtimer_base(timer, &flags);
+
+        return rem;
+}
+EXPORT_SYMBOL_GPL(hrtimer_get_remaining);
+
+#ifdef CONFIG_NO_HZ_COMMON
+/**
+ * hrtimer_get_next_event - get the time until next expiry event
+ *
+ * Returns the delta to the next expiry event or KTIME_MAX if no timer
+ * is pending.
+ */
+ktime_t hrtimer_get_next_event(void)
+{
+        struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
+        struct hrtimer_clock_base *base = cpu_base->clock_base;
+        ktime_t delta, mindelta = { .tv64 = KTIME_MAX };
+        unsigned long flags;
+        int i;
+
+        raw_spin_lock_irqsave(&cpu_base->lock, flags);
+
+        if (!hrtimer_hres_active()) {
+                for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
+                        struct hrtimer *timer;
+                        struct timerqueue_node *next;
+
+                        next = timerqueue_getnext(&base->active);
+                        if (!next)
+                                continue;
+
+                        timer = container_of(next, struct hrtimer, node);
+                        delta.tv64 = hrtimer_get_expires_tv64(timer);
+                        delta = ktime_sub(delta, base->get_time());
+                        if (delta.tv64 < mindelta.tv64)
+                                mindelta.tv64 = delta.tv64;
+                }
+        }
+
+        raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
+
+        if (mindelta.tv64 < 0)
+                mindelta.tv64 = 0;
+        return mindelta;
+}
+#endif
+
+static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
+                           enum hrtimer_mode mode)
+{
+        struct hrtimer_cpu_base *cpu_base;
+        int base;
+
+        memset(timer, 0, sizeof(struct hrtimer));
+
+        cpu_base = &__raw_get_cpu_var(hrtimer_bases);
+
+        if (clock_id == CLOCK_REALTIME && mode != HRTIMER_MODE_ABS)
+                clock_id = CLOCK_MONOTONIC;
+
+        base = hrtimer_clockid_to_base(clock_id);
+        timer->base = &cpu_base->clock_base[base];
+        timerqueue_init(&timer->node);
+
+#ifdef CONFIG_TIMER_STATS
+        timer->start_site = NULL;
+        timer->start_pid = -1;
+        memset(timer->start_comm, 0, TASK_COMM_LEN);
+#endif
+}
+
+/**
+ * hrtimer_init - initialize a timer to the given clock
+ * @timer:      the timer to be initialized
+ * @clock_id:   the clock to be used
+ * @mode:       timer mode abs/rel
+ */
+void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
+                  enum hrtimer_mode mode)
+{
+        debug_init(timer, clock_id, mode);
+        __hrtimer_init(timer, clock_id, mode);
+}
+EXPORT_SYMBOL_GPL(hrtimer_init);
+
+/**
+ * hrtimer_get_res - get the timer resolution for a clock
+ * @which_clock: which clock to query
+ * @tp:          pointer to timespec variable to store the resolution
+ *
+ * Store the resolution of the clock selected by @which_clock in the
+ * variable pointed to by @tp.
+ */
+int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
+{
+        struct hrtimer_cpu_base *cpu_base;
+        int base = hrtimer_clockid_to_base(which_clock);
+
+        cpu_base = &__raw_get_cpu_var(hrtimer_bases);
+        *tp = ktime_to_timespec(cpu_base->clock_base[base].resolution);
+
+        return 0;
+}
+EXPORT_SYMBOL_GPL(hrtimer_get_res);
+
+static void __run_hrtimer(struct hrtimer *timer, ktime_t *now)
+{
+        struct hrtimer_clock_base *base = timer->base;
+        struct hrtimer_cpu_base *cpu_base = base->cpu_base;
+        enum hrtimer_restart (*fn)(struct hrtimer *);
+        int restart;
+
+        WARN_ON(!irqs_disabled());
+
+        debug_deactivate(timer);
+        __remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0);
+        timer_stats_account_hrtimer(timer);
+        fn = timer->function;
+
+        /*
+         * Because we run timers from hardirq context, there is no chance
+         * they get migrated to another cpu, therefore its safe to unlock
+         * the timer base.
+         */
+        raw_spin_unlock(&cpu_base->lock);
+        trace_hrtimer_expire_entry(timer, now);
+        restart = fn(timer);
+        trace_hrtimer_expire_exit(timer);
+        raw_spin_lock(&cpu_base->lock);
+
+        /*
+         * Note: We clear the CALLBACK bit after enqueue_hrtimer and
+         * we do not reprogramm the event hardware. Happens either in
+         * hrtimer_start_range_ns() or in hrtimer_interrupt()
+         */
+        if (restart != HRTIMER_NORESTART) {
+                BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
+                enqueue_hrtimer(timer, base);
+        }
+
+        WARN_ON_ONCE(!(timer->state & HRTIMER_STATE_CALLBACK));
+
+        timer->state &= ~HRTIMER_STATE_CALLBACK;
+}
+
+#ifdef CONFIG_HIGH_RES_TIMERS
+
+/*
+ * High resolution timer interrupt
+ * Called with interrupts disabled
+ */
+void hrtimer_interrupt(struct clock_event_device *dev)
+{
+        struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
+        ktime_t expires_next, now, entry_time, delta;
+        int i, retries = 0;
+
+        BUG_ON(!cpu_base->hres_active);
+        cpu_base->nr_events++;
+        dev->next_event.tv64 = KTIME_MAX;
+
+        raw_spin_lock(&cpu_base->lock);
+        entry_time = now = hrtimer_update_base(cpu_base);
+retry:
+        expires_next.tv64 = KTIME_MAX;
+        /*
+         * We set expires_next to KTIME_MAX here with cpu_base->lock
+         * held to prevent that a timer is enqueued in our queue via
+         * the migration code. This does not affect enqueueing of
+         * timers which run their callback and need to be requeued on
+         * this CPU.
+         */
+        cpu_base->expires_next.tv64 = KTIME_MAX;
+
+        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
+                struct hrtimer_clock_base *base;
+                struct timerqueue_node *node;
+                ktime_t basenow;
+
+                if (!(cpu_base->active_bases & (1 << i)))
+                        continue;
+
+                base = cpu_base->clock_base + i;
+                basenow = ktime_add(now, base->offset);
+
+                while ((node = timerqueue_getnext(&base->active))) {
+                        struct hrtimer *timer;
+
+                        timer = container_of(node, struct hrtimer, node);
+
+                        /*
+                         * The immediate goal for using the softexpires is
+                         * minimizing wakeups, not running timers at the
+                         * earliest interrupt after their soft expiration.
+                         * This allows us to avoid using a Priority Search
+                         * Tree, which can answer a stabbing querry for
+                         * overlapping intervals and instead use the simple
+                         * BST we already have.
+                         * We don't add extra wakeups by delaying timers that
+                         * are right-of a not yet expired timer, because that
+                         * timer will have to trigger a wakeup anyway.
+                         */
+
+                        if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer)) {
+                                ktime_t expires;
+
+                                expires = ktime_sub(hrtimer_get_expires(timer),
+                                                    base->offset);
+                                if (expires.tv64 < 0)
+                                        expires.tv64 = KTIME_MAX;
+                                if (expires.tv64 < expires_next.tv64)
+                                        expires_next = expires;
+                                break;
+                        }
+
+                        __run_hrtimer(timer, &basenow);
+                }
+        }
+
+        /*
+         * Store the new expiry value so the migration code can verify
+         * against it.
+         */
+        cpu_base->expires_next = expires_next;
+        raw_spin_unlock(&cpu_base->lock);
+
+        /* Reprogramming necessary ? */
+        if (expires_next.tv64 == KTIME_MAX ||
+            !tick_program_event(expires_next, 0)) {
+                cpu_base->hang_detected = 0;
+                return;
+        }
+
+        /*
+         * The next timer was already expired due to:
+         * - tracing
+         * - long lasting callbacks
+         * - being scheduled away when running in a VM
+         *
+         * We need to prevent that we loop forever in the hrtimer
+         * interrupt routine. We give it 3 attempts to avoid
+         * overreacting on some spurious event.
+         *
+         * Acquire base lock for updating the offsets and retrieving
+         * the current time.
+         */
+        raw_spin_lock(&cpu_base->lock);
+        now = hrtimer_update_base(cpu_base);
+        cpu_base->nr_retries++;
+        if (++retries < 3)
+                goto retry;
+        /*
+         * Give the system a chance to do something else than looping
+         * here. We stored the entry time, so we know exactly how long
+         * we spent here. We schedule the next event this amount of
+         * time away.
+         */
+        cpu_base->nr_hangs++;
+        cpu_base->hang_detected = 1;
+        raw_spin_unlock(&cpu_base->lock);
+        delta = ktime_sub(now, entry_time);
+        if (delta.tv64 > cpu_base->max_hang_time.tv64)
+                cpu_base->max_hang_time = delta;
+        /*
+         * Limit it to a sensible value as we enforce a longer
+         * delay. Give the CPU at least 100ms to catch up.
+         */
+        if (delta.tv64 > 100 * NSEC_PER_MSEC)
+                expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
+        else
+                expires_next = ktime_add(now, delta);
+        tick_program_event(expires_next, 1);
+        printk_once(KERN_WARNING "hrtimer: interrupt took %llu ns\n",
+                    ktime_to_ns(delta));
+}
+
+/*
+ * local version of hrtimer_peek_ahead_timers() called with interrupts
+ * disabled.
+ */
+static void __hrtimer_peek_ahead_timers(void)
+{
+        struct tick_device *td;
+
+        if (!hrtimer_hres_active())
+                return;
+
+        td = &__get_cpu_var(tick_cpu_device);
+        if (td && td->evtdev)
+                hrtimer_interrupt(td->evtdev);
+}
+
+/**
+ * hrtimer_peek_ahead_timers -- run soft-expired timers now
+ *
+ * hrtimer_peek_ahead_timers will peek at the timer queue of
+ * the current cpu and check if there are any timers for which
+ * the soft expires time has passed. If any such timers exist,
+ * they are run immediately and then removed from the timer queue.
+ *
+ */
+void hrtimer_peek_ahead_timers(void)
+{
+        unsigned long flags;
+
+        local_irq_save(flags);
+        __hrtimer_peek_ahead_timers();
+        local_irq_restore(flags);
+}
+
+static void run_hrtimer_softirq(struct softirq_action *h)
+{
+        hrtimer_peek_ahead_timers();
+}
+
+#else /* CONFIG_HIGH_RES_TIMERS */
+
+static inline void __hrtimer_peek_ahead_timers(void) { }
+
+#endif  /* !CONFIG_HIGH_RES_TIMERS */
+
+/*
+ * Called from timer softirq every jiffy, expire hrtimers:
+ *
+ * For HRT its the fall back code to run the softirq in the timer
+ * softirq context in case the hrtimer initialization failed or has
+ * not been done yet.
+ */
+void hrtimer_run_pending(void)
+{
+        if (hrtimer_hres_active())
+                return;
+
+        /*
+         * This _is_ ugly: We have to check in the softirq context,
+         * whether we can switch to highres and / or nohz mode. The
+         * clocksource switch happens in the timer interrupt with
+         * xtime_lock held. Notification from there only sets the
+         * check bit in the tick_oneshot code, otherwise we might
+         * deadlock vs. xtime_lock.
+         */
+        if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
+                hrtimer_switch_to_hres();
+}
+
+/*
+ * Called from hardirq context every jiffy
+ */
+void hrtimer_run_queues(void)
+{
+        struct timerqueue_node *node;
+        struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
+        struct hrtimer_clock_base *base;
+        int index, gettime = 1;
+
+        if (hrtimer_hres_active())
+                return;
+
+        for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {
+                base = &cpu_base->clock_base[index];
+                if (!timerqueue_getnext(&base->active))
+                        continue;
+
+                if (gettime) {
+                        hrtimer_get_softirq_time(cpu_base);
+                        gettime = 0;
+                }
+
+                raw_spin_lock(&cpu_base->lock);
+
+                while ((node = timerqueue_getnext(&base->active))) {
+                        struct hrtimer *timer;
+
+                        timer = container_of(node, struct hrtimer, node);
+                        if (base->softirq_time.tv64 <=
+                                        hrtimer_get_expires_tv64(timer))
+                                break;
+
+                        __run_hrtimer(timer, &base->softirq_time);
+                }
+                raw_spin_unlock(&cpu_base->lock);
+        }
+}
+
+/*
+ * Sleep related functions:
+ */
+static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
+{
+        struct hrtimer_sleeper *t =
+                container_of(timer, struct hrtimer_sleeper, timer);
+        struct task_struct *task = t->task;
+
+        t->task = NULL;
+        if (task)
+                wake_up_process(task);
+
+        return HRTIMER_NORESTART;
+}
+
+void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task)
+{
+        sl->timer.function = hrtimer_wakeup;
+        sl->task = task;
+}
+EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
+
+static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
+{
+        hrtimer_init_sleeper(t, current);
+
+        do {
+                set_current_state(TASK_INTERRUPTIBLE);
+                hrtimer_start_expires(&t->timer, mode);
+                if (!hrtimer_active(&t->timer))
+                        t->task = NULL;
+
+                if (likely(t->task))
+                        freezable_schedule();
+
+                hrtimer_cancel(&t->timer);
+                mode = HRTIMER_MODE_ABS;
+
+        } while (t->task && !signal_pending(current));
+
+        __set_current_state(TASK_RUNNING);
+
+        return t->task == NULL;
+}
+
+static int update_rmtp(struct hrtimer *timer, struct timespec __user *rmtp)
+{
+        struct timespec rmt;
+        ktime_t rem;
+
+        rem = hrtimer_expires_remaining(timer);
+        if (rem.tv64 <= 0)
+                return 0;
+        rmt = ktime_to_timespec(rem);
+
+        if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
+                return -EFAULT;
+
+        return 1;
+}
+
+long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
+{
+        struct hrtimer_sleeper t;
+        struct timespec __user  *rmtp;
+        int ret = 0;
+
+        hrtimer_init_on_stack(&t.timer, restart->nanosleep.clockid,
+                                HRTIMER_MODE_ABS);
+        hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
+
+        if (do_nanosleep(&t, HRTIMER_MODE_ABS))
+                goto out;
+
+        rmtp = restart->nanosleep.rmtp;
+        if (rmtp) {
+                ret = update_rmtp(&t.timer, rmtp);
+                if (ret <= 0)
+                        goto out;
+        }
+
+        /* The other values in restart are already filled in */
+        ret = -ERESTART_RESTARTBLOCK;
+out:
+        destroy_hrtimer_on_stack(&t.timer);
+        return ret;
+}
+
+long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
+                       const enum hrtimer_mode mode, const clockid_t clockid)
+{
+        struct restart_block *restart;
+        struct hrtimer_sleeper t;
+        int ret = 0;
+        unsigned long slack;
+
+        slack = current->timer_slack_ns;
+        if (dl_task(current) || rt_task(current))
+                slack = 0;
+
+        hrtimer_init_on_stack(&t.timer, clockid, mode);
+        hrtimer_set_expires_range_ns(&t.timer, timespec_to_ktime(*rqtp), slack);
+        if (do_nanosleep(&t, mode))
+                goto out;
+
+        /* Absolute timers do not update the rmtp value and restart: */
+        if (mode == HRTIMER_MODE_ABS) {
+                ret = -ERESTARTNOHAND;
+                goto out;
+        }
+
+        if (rmtp) {
+                ret = update_rmtp(&t.timer, rmtp);
+                if (ret <= 0)
+                        goto out;
+        }
+
+        restart = &current_thread_info()->restart_block;
+        restart->fn = hrtimer_nanosleep_restart;
+        restart->nanosleep.clockid = t.timer.base->clockid;
+        restart->nanosleep.rmtp = rmtp;
+        restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
+
+        ret = -ERESTART_RESTARTBLOCK;
+out:
+        destroy_hrtimer_on_stack(&t.timer);
+        return ret;
+}
+
+SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
+                struct timespec __user *, rmtp)
+{
+        struct timespec tu;
+
+        if (copy_from_user(&tu, rqtp, sizeof(tu)))
+                return -EFAULT;
+
+        if (!timespec_valid(&tu))
+                return -EINVAL;
+
+        return hrtimer_nanosleep(&tu, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
+}
+
+/*
+ * Functions related to boot-time initialization:
+ */
+static void init_hrtimers_cpu(int cpu)
+{
+        struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
+        int i;
+
+        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
+                cpu_base->clock_base[i].cpu_base = cpu_base;
+                timerqueue_init_head(&cpu_base->clock_base[i].active);
+        }
+
+        hrtimer_init_hres(cpu_base);
+}
+
+#ifdef CONFIG_HOTPLUG_CPU
+
+static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
+                                struct hrtimer_clock_base *new_base)
+{
+        struct hrtimer *timer;
+        struct timerqueue_node *node;
+
+        while ((node = timerqueue_getnext(&old_base->active))) {
+                timer = container_of(node, struct hrtimer, node);
+                BUG_ON(hrtimer_callback_running(timer));
+                debug_deactivate(timer);
+
+                /*
+                 * Mark it as STATE_MIGRATE not INACTIVE otherwise the
+                 * timer could be seen as !active and just vanish away
+                 * under us on another CPU
+                 */
+                __remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0);
+                timer->base = new_base;
+                /*
+                 * Enqueue the timers on the new cpu. This does not
+                 * reprogram the event device in case the timer
+                 * expires before the earliest on this CPU, but we run
+                 * hrtimer_interrupt after we migrated everything to
+                 * sort out already expired timers and reprogram the
+                 * event device.
+                 */
+                enqueue_hrtimer(timer, new_base);
+
+                /* Clear the migration state bit */
+                timer->state &= ~HRTIMER_STATE_MIGRATE;
+        }
+}
+
+static void migrate_hrtimers(int scpu)
+{
+        struct hrtimer_cpu_base *old_base, *new_base;
+        int i;
+
+        BUG_ON(cpu_online(scpu));
+        tick_cancel_sched_timer(scpu);
+
+        local_irq_disable();
+        old_base = &per_cpu(hrtimer_bases, scpu);
+        new_base = &__get_cpu_var(hrtimer_bases);
+        /*
+         * The caller is globally serialized and nobody else
+         * takes two locks at once, deadlock is not possible.
+         */
+        raw_spin_lock(&new_base->lock);
+        raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
+
+        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
+                migrate_hrtimer_list(&old_base->clock_base[i],
+                                     &new_base->clock_base[i]);
+        }
+
+        raw_spin_unlock(&old_base->lock);
+        raw_spin_unlock(&new_base->lock);
+
+        /* Check, if we got expired work to do */
+        __hrtimer_peek_ahead_timers();
+        local_irq_enable();
+}
+
+#endif /* CONFIG_HOTPLUG_CPU */
+
+static int hrtimer_cpu_notify(struct notifier_block *self,
+                                        unsigned long action, void *hcpu)
+{
+        int scpu = (long)hcpu;
+
+        switch (action) {
+
+        case CPU_UP_PREPARE:
+        case CPU_UP_PREPARE_FROZEN:
+                init_hrtimers_cpu(scpu);
+                break;
+
+#ifdef CONFIG_HOTPLUG_CPU
+        case CPU_DYING:
+        case CPU_DYING_FROZEN:
+                clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DYING, &scpu);
+                break;
+        case CPU_DEAD:
+        case CPU_DEAD_FROZEN:
+        {
+                clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu);
+                migrate_hrtimers(scpu);
+                break;
+        }
+#endif
+
+        default:
+                break;
+        }
+
+        return NOTIFY_OK;
+}
+
+static struct notifier_block hrtimers_nb = {
+        .notifier_call = hrtimer_cpu_notify,
+};
+
+void __init hrtimers_init(void)
+{
+        hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
+                          (void *)(long)smp_processor_id());
+        register_cpu_notifier(&hrtimers_nb);
+#ifdef CONFIG_HIGH_RES_TIMERS
+        open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq);
+#endif
+}
+
+/**
+ * schedule_hrtimeout_range_clock - sleep until timeout
+ * @expires:    timeout value (ktime_t)
+ * @delta:      slack in expires timeout (ktime_t)
+ * @mode:       timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
+ * @clock:      timer clock, CLOCK_MONOTONIC or CLOCK_REALTIME
+ */
+int __sched
+schedule_hrtimeout_range_clock(ktime_t *expires, unsigned long delta,
+                               const enum hrtimer_mode mode, int clock)
+{
+        struct hrtimer_sleeper t;
+
+        /*
+         * Optimize when a zero timeout value is given. It does not
+         * matter whether this is an absolute or a relative time.
+         */
+        if (expires && !expires->tv64) {
+                __set_current_state(TASK_RUNNING);
+                return 0;
+        }
+
+        /*
+         * A NULL parameter means "infinite"
+         */
+        if (!expires) {
+                schedule();
+                __set_current_state(TASK_RUNNING);
+                return -EINTR;
+        }
+
+        hrtimer_init_on_stack(&t.timer, clock, mode);
+        hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
+
+        hrtimer_init_sleeper(&t, current);
+
+        hrtimer_start_expires(&t.timer, mode);
+        if (!hrtimer_active(&t.timer))
+                t.task = NULL;
+
+        if (likely(t.task))
+                schedule();
+
+        hrtimer_cancel(&t.timer);
+        destroy_hrtimer_on_stack(&t.timer);
+
+        __set_current_state(TASK_RUNNING);
+
+        return !t.task ? 0 : -EINTR;
+}
+
+/**
+ * schedule_hrtimeout_range - sleep until timeout
+ * @expires:    timeout value (ktime_t)
+ * @delta:      slack in expires timeout (ktime_t)
+ * @mode:       timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
+ *
+ * Make the current task sleep until the given expiry time has
+ * elapsed. The routine will return immediately unless
+ * the current task state has been set (see set_current_state()).
+ *
+ * The @delta argument gives the kernel the freedom to schedule the
+ * actual wakeup to a time that is both power and performance friendly.
+ * The kernel give the normal best effort behavior for "@expires+@delta",
+ * but may decide to fire the timer earlier, but no earlier than @expires.
+ *
+ * You can set the task state as follows -
+ *
+ * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
+ * pass before the routine returns.
+ *
+ * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
+ * delivered to the current task.
+ *
+ * The current task state is guaranteed to be TASK_RUNNING when this
+ * routine returns.
+ *
+ * Returns 0 when the timer has expired otherwise -EINTR
+ */
+int __sched schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
+                                     const enum hrtimer_mode mode)
+{
+        return schedule_hrtimeout_range_clock(expires, delta, mode,
+                                              CLOCK_MONOTONIC);
+}
+EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
+
+/**
+ * schedule_hrtimeout - sleep until timeout
+ * @expires:    timeout value (ktime_t)
+ * @mode:       timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
+ *
+ * Make the current task sleep until the given expiry time has
+ * elapsed. The routine will return immediately unless
+ * the current task state has been set (see set_current_state()).
+ *
+ * You can set the task state as follows -
+ *
+ * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
+ * pass before the routine returns.
+ *
+ * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
+ * delivered to the current task.
+ *
+ * The current task state is guaranteed to be TASK_RUNNING when this
+ * routine returns.
+ *
+ * Returns 0 when the timer has expired otherwise -EINTR
+ */
+int __sched schedule_hrtimeout(ktime_t *expires,
+                               const enum hrtimer_mode mode)
+{
+        return schedule_hrtimeout_range(expires, 0, mode);
+}
+EXPORT_SYMBOL_GPL(schedule_hrtimeout);