Root/kernel/hrtimer.c

1/*
2 * linux/kernel/hrtimer.c
3 *
4 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
5 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
6 * Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner
7 *
8 * High-resolution kernel timers
9 *
10 * In contrast to the low-resolution timeout API implemented in
11 * kernel/timer.c, hrtimers provide finer resolution and accuracy
12 * depending on system configuration and capabilities.
13 *
14 * These timers are currently used for:
15 * - itimers
16 * - POSIX timers
17 * - nanosleep
18 * - precise in-kernel timing
19 *
20 * Started by: Thomas Gleixner and Ingo Molnar
21 *
22 * Credits:
23 * based on kernel/timer.c
24 *
25 * Help, testing, suggestions, bugfixes, improvements were
26 * provided by:
27 *
28 * George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
29 * et. al.
30 *
31 * For licencing details see kernel-base/COPYING
32 */
33
34#include <linux/cpu.h>
35#include <linux/export.h>
36#include <linux/percpu.h>
37#include <linux/hrtimer.h>
38#include <linux/notifier.h>
39#include <linux/syscalls.h>
40#include <linux/kallsyms.h>
41#include <linux/interrupt.h>
42#include <linux/tick.h>
43#include <linux/seq_file.h>
44#include <linux/err.h>
45#include <linux/debugobjects.h>
46#include <linux/sched.h>
47#include <linux/sched/sysctl.h>
48#include <linux/sched/rt.h>
49#include <linux/sched/deadline.h>
50#include <linux/timer.h>
51#include <linux/freezer.h>
52
53#include <asm/uaccess.h>
54
55#include <trace/events/timer.h>
56
57/*
58 * The timer bases:
59 *
60 * There are more clockids then hrtimer bases. Thus, we index
61 * into the timer bases by the hrtimer_base_type enum. When trying
62 * to reach a base using a clockid, hrtimer_clockid_to_base()
63 * is used to convert from clockid to the proper hrtimer_base_type.
64 */
65DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
66{
67
68    .lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
69    .clock_base =
70    {
71        {
72            .index = HRTIMER_BASE_MONOTONIC,
73            .clockid = CLOCK_MONOTONIC,
74            .get_time = &ktime_get,
75            .resolution = KTIME_LOW_RES,
76        },
77        {
78            .index = HRTIMER_BASE_REALTIME,
79            .clockid = CLOCK_REALTIME,
80            .get_time = &ktime_get_real,
81            .resolution = KTIME_LOW_RES,
82        },
83        {
84            .index = HRTIMER_BASE_BOOTTIME,
85            .clockid = CLOCK_BOOTTIME,
86            .get_time = &ktime_get_boottime,
87            .resolution = KTIME_LOW_RES,
88        },
89        {
90            .index = HRTIMER_BASE_TAI,
91            .clockid = CLOCK_TAI,
92            .get_time = &ktime_get_clocktai,
93            .resolution = KTIME_LOW_RES,
94        },
95    }
96};
97
98static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
99    [CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
100    [CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
101    [CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
102    [CLOCK_TAI] = HRTIMER_BASE_TAI,
103};
104
105static inline int hrtimer_clockid_to_base(clockid_t clock_id)
106{
107    return hrtimer_clock_to_base_table[clock_id];
108}
109
110
111/*
112 * Get the coarse grained time at the softirq based on xtime and
113 * wall_to_monotonic.
114 */
115static void hrtimer_get_softirq_time(struct hrtimer_cpu_base *base)
116{
117    ktime_t xtim, mono, boot;
118    struct timespec xts, tom, slp;
119    s32 tai_offset;
120
121    get_xtime_and_monotonic_and_sleep_offset(&xts, &tom, &slp);
122    tai_offset = timekeeping_get_tai_offset();
123
124    xtim = timespec_to_ktime(xts);
125    mono = ktime_add(xtim, timespec_to_ktime(tom));
126    boot = ktime_add(mono, timespec_to_ktime(slp));
127    base->clock_base[HRTIMER_BASE_REALTIME].softirq_time = xtim;
128    base->clock_base[HRTIMER_BASE_MONOTONIC].softirq_time = mono;
129    base->clock_base[HRTIMER_BASE_BOOTTIME].softirq_time = boot;
130    base->clock_base[HRTIMER_BASE_TAI].softirq_time =
131                ktime_add(xtim, ktime_set(tai_offset, 0));
132}
133
134/*
135 * Functions and macros which are different for UP/SMP systems are kept in a
136 * single place
137 */
138#ifdef CONFIG_SMP
139
140/*
141 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
142 * means that all timers which are tied to this base via timer->base are
143 * locked, and the base itself is locked too.
144 *
145 * So __run_timers/migrate_timers can safely modify all timers which could
146 * be found on the lists/queues.
147 *
148 * When the timer's base is locked, and the timer removed from list, it is
149 * possible to set timer->base = NULL and drop the lock: the timer remains
150 * locked.
151 */
152static
153struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
154                         unsigned long *flags)
155{
156    struct hrtimer_clock_base *base;
157
158    for (;;) {
159        base = timer->base;
160        if (likely(base != NULL)) {
161            raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
162            if (likely(base == timer->base))
163                return base;
164            /* The timer has migrated to another CPU: */
165            raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
166        }
167        cpu_relax();
168    }
169}
170
171/*
172 * With HIGHRES=y we do not migrate the timer when it is expiring
173 * before the next event on the target cpu because we cannot reprogram
174 * the target cpu hardware and we would cause it to fire late.
175 *
176 * Called with cpu_base->lock of target cpu held.
177 */
178static int
179hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
180{
181#ifdef CONFIG_HIGH_RES_TIMERS
182    ktime_t expires;
183
184    if (!new_base->cpu_base->hres_active)
185        return 0;
186
187    expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
188    return expires.tv64 <= new_base->cpu_base->expires_next.tv64;
189#else
190    return 0;
191#endif
192}
193
194/*
195 * Switch the timer base to the current CPU when possible.
196 */
197static inline struct hrtimer_clock_base *
198switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
199            int pinned)
200{
201    struct hrtimer_clock_base *new_base;
202    struct hrtimer_cpu_base *new_cpu_base;
203    int this_cpu = smp_processor_id();
204    int cpu = get_nohz_timer_target(pinned);
205    int basenum = base->index;
206
207again:
208    new_cpu_base = &per_cpu(hrtimer_bases, cpu);
209    new_base = &new_cpu_base->clock_base[basenum];
210
211    if (base != new_base) {
212        /*
213         * We are trying to move timer to new_base.
214         * However we can't change timer's base while it is running,
215         * so we keep it on the same CPU. No hassle vs. reprogramming
216         * the event source in the high resolution case. The softirq
217         * code will take care of this when the timer function has
218         * completed. There is no conflict as we hold the lock until
219         * the timer is enqueued.
220         */
221        if (unlikely(hrtimer_callback_running(timer)))
222            return base;
223
224        /* See the comment in lock_timer_base() */
225        timer->base = NULL;
226        raw_spin_unlock(&base->cpu_base->lock);
227        raw_spin_lock(&new_base->cpu_base->lock);
228
229        if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
230            cpu = this_cpu;
231            raw_spin_unlock(&new_base->cpu_base->lock);
232            raw_spin_lock(&base->cpu_base->lock);
233            timer->base = base;
234            goto again;
235        }
236        timer->base = new_base;
237    } else {
238        if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
239            cpu = this_cpu;
240            goto again;
241        }
242    }
243    return new_base;
244}
245
246#else /* CONFIG_SMP */
247
248static inline struct hrtimer_clock_base *
249lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
250{
251    struct hrtimer_clock_base *base = timer->base;
252
253    raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
254
255    return base;
256}
257
258# define switch_hrtimer_base(t, b, p) (b)
259
260#endif /* !CONFIG_SMP */
261
262/*
263 * Functions for the union type storage format of ktime_t which are
264 * too large for inlining:
265 */
266#if BITS_PER_LONG < 64
267# ifndef CONFIG_KTIME_SCALAR
268/**
269 * ktime_add_ns - Add a scalar nanoseconds value to a ktime_t variable
270 * @kt: addend
271 * @nsec: the scalar nsec value to add
272 *
273 * Returns the sum of kt and nsec in ktime_t format
274 */
275ktime_t ktime_add_ns(const ktime_t kt, u64 nsec)
276{
277    ktime_t tmp;
278
279    if (likely(nsec < NSEC_PER_SEC)) {
280        tmp.tv64 = nsec;
281    } else {
282        unsigned long rem = do_div(nsec, NSEC_PER_SEC);
283
284        /* Make sure nsec fits into long */
285        if (unlikely(nsec > KTIME_SEC_MAX))
286            return (ktime_t){ .tv64 = KTIME_MAX };
287
288        tmp = ktime_set((long)nsec, rem);
289    }
290
291    return ktime_add(kt, tmp);
292}
293
294EXPORT_SYMBOL_GPL(ktime_add_ns);
295
296/**
297 * ktime_sub_ns - Subtract a scalar nanoseconds value from a ktime_t variable
298 * @kt: minuend
299 * @nsec: the scalar nsec value to subtract
300 *
301 * Returns the subtraction of @nsec from @kt in ktime_t format
302 */
303ktime_t ktime_sub_ns(const ktime_t kt, u64 nsec)
304{
305    ktime_t tmp;
306
307    if (likely(nsec < NSEC_PER_SEC)) {
308        tmp.tv64 = nsec;
309    } else {
310        unsigned long rem = do_div(nsec, NSEC_PER_SEC);
311
312        tmp = ktime_set((long)nsec, rem);
313    }
314
315    return ktime_sub(kt, tmp);
316}
317
318EXPORT_SYMBOL_GPL(ktime_sub_ns);
319# endif /* !CONFIG_KTIME_SCALAR */
320
321/*
322 * Divide a ktime value by a nanosecond value
323 */
324u64 ktime_divns(const ktime_t kt, s64 div)
325{
326    u64 dclc;
327    int sft = 0;
328
329    dclc = ktime_to_ns(kt);
330    /* Make sure the divisor is less than 2^32: */
331    while (div >> 32) {
332        sft++;
333        div >>= 1;
334    }
335    dclc >>= sft;
336    do_div(dclc, (unsigned long) div);
337
338    return dclc;
339}
340#endif /* BITS_PER_LONG >= 64 */
341
342/*
343 * Add two ktime values and do a safety check for overflow:
344 */
345ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
346{
347    ktime_t res = ktime_add(lhs, rhs);
348
349    /*
350     * We use KTIME_SEC_MAX here, the maximum timeout which we can
351     * return to user space in a timespec:
352     */
353    if (res.tv64 < 0 || res.tv64 < lhs.tv64 || res.tv64 < rhs.tv64)
354        res = ktime_set(KTIME_SEC_MAX, 0);
355
356    return res;
357}
358
359EXPORT_SYMBOL_GPL(ktime_add_safe);
360
361#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
362
363static struct debug_obj_descr hrtimer_debug_descr;
364
365static void *hrtimer_debug_hint(void *addr)
366{
367    return ((struct hrtimer *) addr)->function;
368}
369
370/*
371 * fixup_init is called when:
372 * - an active object is initialized
373 */
374static int hrtimer_fixup_init(void *addr, enum debug_obj_state state)
375{
376    struct hrtimer *timer = addr;
377
378    switch (state) {
379    case ODEBUG_STATE_ACTIVE:
380        hrtimer_cancel(timer);
381        debug_object_init(timer, &hrtimer_debug_descr);
382        return 1;
383    default:
384        return 0;
385    }
386}
387
388/*
389 * fixup_activate is called when:
390 * - an active object is activated
391 * - an unknown object is activated (might be a statically initialized object)
392 */
393static int hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
394{
395    switch (state) {
396
397    case ODEBUG_STATE_NOTAVAILABLE:
398        WARN_ON_ONCE(1);
399        return 0;
400
401    case ODEBUG_STATE_ACTIVE:
402        WARN_ON(1);
403
404    default:
405        return 0;
406    }
407}
408
409/*
410 * fixup_free is called when:
411 * - an active object is freed
412 */
413static int hrtimer_fixup_free(void *addr, enum debug_obj_state state)
414{
415    struct hrtimer *timer = addr;
416
417    switch (state) {
418    case ODEBUG_STATE_ACTIVE:
419        hrtimer_cancel(timer);
420        debug_object_free(timer, &hrtimer_debug_descr);
421        return 1;
422    default:
423        return 0;
424    }
425}
426
427static struct debug_obj_descr hrtimer_debug_descr = {
428    .name = "hrtimer",
429    .debug_hint = hrtimer_debug_hint,
430    .fixup_init = hrtimer_fixup_init,
431    .fixup_activate = hrtimer_fixup_activate,
432    .fixup_free = hrtimer_fixup_free,
433};
434
435static inline void debug_hrtimer_init(struct hrtimer *timer)
436{
437    debug_object_init(timer, &hrtimer_debug_descr);
438}
439
440static inline void debug_hrtimer_activate(struct hrtimer *timer)
441{
442    debug_object_activate(timer, &hrtimer_debug_descr);
443}
444
445static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
446{
447    debug_object_deactivate(timer, &hrtimer_debug_descr);
448}
449
450static inline void debug_hrtimer_free(struct hrtimer *timer)
451{
452    debug_object_free(timer, &hrtimer_debug_descr);
453}
454
455static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
456               enum hrtimer_mode mode);
457
458void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
459               enum hrtimer_mode mode)
460{
461    debug_object_init_on_stack(timer, &hrtimer_debug_descr);
462    __hrtimer_init(timer, clock_id, mode);
463}
464EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
465
466void destroy_hrtimer_on_stack(struct hrtimer *timer)
467{
468    debug_object_free(timer, &hrtimer_debug_descr);
469}
470
471#else
472static inline void debug_hrtimer_init(struct hrtimer *timer) { }
473static inline void debug_hrtimer_activate(struct hrtimer *timer) { }
474static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
475#endif
476
477static inline void
478debug_init(struct hrtimer *timer, clockid_t clockid,
479       enum hrtimer_mode mode)
480{
481    debug_hrtimer_init(timer);
482    trace_hrtimer_init(timer, clockid, mode);
483}
484
485static inline void debug_activate(struct hrtimer *timer)
486{
487    debug_hrtimer_activate(timer);
488    trace_hrtimer_start(timer);
489}
490
491static inline void debug_deactivate(struct hrtimer *timer)
492{
493    debug_hrtimer_deactivate(timer);
494    trace_hrtimer_cancel(timer);
495}
496
497/* High resolution timer related functions */
498#ifdef CONFIG_HIGH_RES_TIMERS
499
500/*
501 * High resolution timer enabled ?
502 */
503static int hrtimer_hres_enabled __read_mostly = 1;
504
505/*
506 * Enable / Disable high resolution mode
507 */
508static int __init setup_hrtimer_hres(char *str)
509{
510    if (!strcmp(str, "off"))
511        hrtimer_hres_enabled = 0;
512    else if (!strcmp(str, "on"))
513        hrtimer_hres_enabled = 1;
514    else
515        return 0;
516    return 1;
517}
518
519__setup("highres=", setup_hrtimer_hres);
520
521/*
522 * hrtimer_high_res_enabled - query, if the highres mode is enabled
523 */
524static inline int hrtimer_is_hres_enabled(void)
525{
526    return hrtimer_hres_enabled;
527}
528
529/*
530 * Is the high resolution mode active ?
531 */
532static inline int hrtimer_hres_active(void)
533{
534    return __this_cpu_read(hrtimer_bases.hres_active);
535}
536
537/*
538 * Reprogram the event source with checking both queues for the
539 * next event
540 * Called with interrupts disabled and base->lock held
541 */
542static void
543hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
544{
545    int i;
546    struct hrtimer_clock_base *base = cpu_base->clock_base;
547    ktime_t expires, expires_next;
548
549    expires_next.tv64 = KTIME_MAX;
550
551    for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
552        struct hrtimer *timer;
553        struct timerqueue_node *next;
554
555        next = timerqueue_getnext(&base->active);
556        if (!next)
557            continue;
558        timer = container_of(next, struct hrtimer, node);
559
560        expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
561        /*
562         * clock_was_set() has changed base->offset so the
563         * result might be negative. Fix it up to prevent a
564         * false positive in clockevents_program_event()
565         */
566        if (expires.tv64 < 0)
567            expires.tv64 = 0;
568        if (expires.tv64 < expires_next.tv64)
569            expires_next = expires;
570    }
571
572    if (skip_equal && expires_next.tv64 == cpu_base->expires_next.tv64)
573        return;
574
575    cpu_base->expires_next.tv64 = expires_next.tv64;
576
577    /*
578     * If a hang was detected in the last timer interrupt then we
579     * leave the hang delay active in the hardware. We want the
580     * system to make progress. That also prevents the following
581     * scenario:
582     * T1 expires 50ms from now
583     * T2 expires 5s from now
584     *
585     * T1 is removed, so this code is called and would reprogram
586     * the hardware to 5s from now. Any hrtimer_start after that
587     * will not reprogram the hardware due to hang_detected being
588     * set. So we'd effectivly block all timers until the T2 event
589     * fires.
590     */
591    if (cpu_base->hang_detected)
592        return;
593
594    if (cpu_base->expires_next.tv64 != KTIME_MAX)
595        tick_program_event(cpu_base->expires_next, 1);
596}
597
598/*
599 * Shared reprogramming for clock_realtime and clock_monotonic
600 *
601 * When a timer is enqueued and expires earlier than the already enqueued
602 * timers, we have to check, whether it expires earlier than the timer for
603 * which the clock event device was armed.
604 *
605 * Called with interrupts disabled and base->cpu_base.lock held
606 */
607static int hrtimer_reprogram(struct hrtimer *timer,
608                 struct hrtimer_clock_base *base)
609{
610    struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
611    ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
612    int res;
613
614    WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
615
616    /*
617     * When the callback is running, we do not reprogram the clock event
618     * device. The timer callback is either running on a different CPU or
619     * the callback is executed in the hrtimer_interrupt context. The
620     * reprogramming is handled either by the softirq, which called the
621     * callback or at the end of the hrtimer_interrupt.
622     */
623    if (hrtimer_callback_running(timer))
624        return 0;
625
626    /*
627     * CLOCK_REALTIME timer might be requested with an absolute
628     * expiry time which is less than base->offset. Nothing wrong
629     * about that, just avoid to call into the tick code, which
630     * has now objections against negative expiry values.
631     */
632    if (expires.tv64 < 0)
633        return -ETIME;
634
635    if (expires.tv64 >= cpu_base->expires_next.tv64)
636        return 0;
637
638    /*
639     * If a hang was detected in the last timer interrupt then we
640     * do not schedule a timer which is earlier than the expiry
641     * which we enforced in the hang detection. We want the system
642     * to make progress.
643     */
644    if (cpu_base->hang_detected)
645        return 0;
646
647    /*
648     * Clockevents returns -ETIME, when the event was in the past.
649     */
650    res = tick_program_event(expires, 0);
651    if (!IS_ERR_VALUE(res))
652        cpu_base->expires_next = expires;
653    return res;
654}
655
656/*
657 * Initialize the high resolution related parts of cpu_base
658 */
659static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
660{
661    base->expires_next.tv64 = KTIME_MAX;
662    base->hres_active = 0;
663}
664
665/*
666 * When High resolution timers are active, try to reprogram. Note, that in case
667 * the state has HRTIMER_STATE_CALLBACK set, no reprogramming and no expiry
668 * check happens. The timer gets enqueued into the rbtree. The reprogramming
669 * and expiry check is done in the hrtimer_interrupt or in the softirq.
670 */
671static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
672                        struct hrtimer_clock_base *base)
673{
674    return base->cpu_base->hres_active && hrtimer_reprogram(timer, base);
675}
676
677static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
678{
679    ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
680    ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
681    ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
682
683    return ktime_get_update_offsets(offs_real, offs_boot, offs_tai);
684}
685
686/*
687 * Retrigger next event is called after clock was set
688 *
689 * Called with interrupts disabled via on_each_cpu()
690 */
691static void retrigger_next_event(void *arg)
692{
693    struct hrtimer_cpu_base *base = &__get_cpu_var(hrtimer_bases);
694
695    if (!hrtimer_hres_active())
696        return;
697
698    raw_spin_lock(&base->lock);
699    hrtimer_update_base(base);
700    hrtimer_force_reprogram(base, 0);
701    raw_spin_unlock(&base->lock);
702}
703
704/*
705 * Switch to high resolution mode
706 */
707static int hrtimer_switch_to_hres(void)
708{
709    int i, cpu = smp_processor_id();
710    struct hrtimer_cpu_base *base = &per_cpu(hrtimer_bases, cpu);
711    unsigned long flags;
712
713    if (base->hres_active)
714        return 1;
715
716    local_irq_save(flags);
717
718    if (tick_init_highres()) {
719        local_irq_restore(flags);
720        printk(KERN_WARNING "Could not switch to high resolution "
721                    "mode on CPU %d\n", cpu);
722        return 0;
723    }
724    base->hres_active = 1;
725    for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)
726        base->clock_base[i].resolution = KTIME_HIGH_RES;
727
728    tick_setup_sched_timer();
729    /* "Retrigger" the interrupt to get things going */
730    retrigger_next_event(NULL);
731    local_irq_restore(flags);
732    return 1;
733}
734
735static void clock_was_set_work(struct work_struct *work)
736{
737    clock_was_set();
738}
739
740static DECLARE_WORK(hrtimer_work, clock_was_set_work);
741
742/*
743 * Called from timekeeping and resume code to reprogramm the hrtimer
744 * interrupt device on all cpus.
745 */
746void clock_was_set_delayed(void)
747{
748    schedule_work(&hrtimer_work);
749}
750
751#else
752
753static inline int hrtimer_hres_active(void) { return 0; }
754static inline int hrtimer_is_hres_enabled(void) { return 0; }
755static inline int hrtimer_switch_to_hres(void) { return 0; }
756static inline void
757hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
758static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
759                        struct hrtimer_clock_base *base)
760{
761    return 0;
762}
763static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
764static inline void retrigger_next_event(void *arg) { }
765
766#endif /* CONFIG_HIGH_RES_TIMERS */
767
768/*
769 * Clock realtime was set
770 *
771 * Change the offset of the realtime clock vs. the monotonic
772 * clock.
773 *
774 * We might have to reprogram the high resolution timer interrupt. On
775 * SMP we call the architecture specific code to retrigger _all_ high
776 * resolution timer interrupts. On UP we just disable interrupts and
777 * call the high resolution interrupt code.
778 */
779void clock_was_set(void)
780{
781#ifdef CONFIG_HIGH_RES_TIMERS
782    /* Retrigger the CPU local events everywhere */
783    on_each_cpu(retrigger_next_event, NULL, 1);
784#endif
785    timerfd_clock_was_set();
786}
787
788/*
789 * During resume we might have to reprogram the high resolution timer
790 * interrupt on all online CPUs. However, all other CPUs will be
791 * stopped with IRQs interrupts disabled so the clock_was_set() call
792 * must be deferred.
793 */
794void hrtimers_resume(void)
795{
796    WARN_ONCE(!irqs_disabled(),
797          KERN_INFO "hrtimers_resume() called with IRQs enabled!");
798
799    /* Retrigger on the local CPU */
800    retrigger_next_event(NULL);
801    /* And schedule a retrigger for all others */
802    clock_was_set_delayed();
803}
804
805static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
806{
807#ifdef CONFIG_TIMER_STATS
808    if (timer->start_site)
809        return;
810    timer->start_site = __builtin_return_address(0);
811    memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
812    timer->start_pid = current->pid;
813#endif
814}
815
816static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
817{
818#ifdef CONFIG_TIMER_STATS
819    timer->start_site = NULL;
820#endif
821}
822
823static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
824{
825#ifdef CONFIG_TIMER_STATS
826    if (likely(!timer_stats_active))
827        return;
828    timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
829                 timer->function, timer->start_comm, 0);
830#endif
831}
832
833/*
834 * Counterpart to lock_hrtimer_base above:
835 */
836static inline
837void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
838{
839    raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
840}
841
842/**
843 * hrtimer_forward - forward the timer expiry
844 * @timer: hrtimer to forward
845 * @now: forward past this time
846 * @interval: the interval to forward
847 *
848 * Forward the timer expiry so it will expire in the future.
849 * Returns the number of overruns.
850 */
851u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
852{
853    u64 orun = 1;
854    ktime_t delta;
855
856    delta = ktime_sub(now, hrtimer_get_expires(timer));
857
858    if (delta.tv64 < 0)
859        return 0;
860
861    if (interval.tv64 < timer->base->resolution.tv64)
862        interval.tv64 = timer->base->resolution.tv64;
863
864    if (unlikely(delta.tv64 >= interval.tv64)) {
865        s64 incr = ktime_to_ns(interval);
866
867        orun = ktime_divns(delta, incr);
868        hrtimer_add_expires_ns(timer, incr * orun);
869        if (hrtimer_get_expires_tv64(timer) > now.tv64)
870            return orun;
871        /*
872         * This (and the ktime_add() below) is the
873         * correction for exact:
874         */
875        orun++;
876    }
877    hrtimer_add_expires(timer, interval);
878
879    return orun;
880}
881EXPORT_SYMBOL_GPL(hrtimer_forward);
882
883/*
884 * enqueue_hrtimer - internal function to (re)start a timer
885 *
886 * The timer is inserted in expiry order. Insertion into the
887 * red black tree is O(log(n)). Must hold the base lock.
888 *
889 * Returns 1 when the new timer is the leftmost timer in the tree.
890 */
891static int enqueue_hrtimer(struct hrtimer *timer,
892               struct hrtimer_clock_base *base)
893{
894    debug_activate(timer);
895
896    timerqueue_add(&base->active, &timer->node);
897    base->cpu_base->active_bases |= 1 << base->index;
898
899    /*
900     * HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the
901     * state of a possibly running callback.
902     */
903    timer->state |= HRTIMER_STATE_ENQUEUED;
904
905    return (&timer->node == base->active.next);
906}
907
908/*
909 * __remove_hrtimer - internal function to remove a timer
910 *
911 * Caller must hold the base lock.
912 *
913 * High resolution timer mode reprograms the clock event device when the
914 * timer is the one which expires next. The caller can disable this by setting
915 * reprogram to zero. This is useful, when the context does a reprogramming
916 * anyway (e.g. timer interrupt)
917 */
918static void __remove_hrtimer(struct hrtimer *timer,
919                 struct hrtimer_clock_base *base,
920                 unsigned long newstate, int reprogram)
921{
922    struct timerqueue_node *next_timer;
923    if (!(timer->state & HRTIMER_STATE_ENQUEUED))
924        goto out;
925
926    next_timer = timerqueue_getnext(&base->active);
927    timerqueue_del(&base->active, &timer->node);
928    if (&timer->node == next_timer) {
929#ifdef CONFIG_HIGH_RES_TIMERS
930        /* Reprogram the clock event device. if enabled */
931        if (reprogram && hrtimer_hres_active()) {
932            ktime_t expires;
933
934            expires = ktime_sub(hrtimer_get_expires(timer),
935                        base->offset);
936            if (base->cpu_base->expires_next.tv64 == expires.tv64)
937                hrtimer_force_reprogram(base->cpu_base, 1);
938        }
939#endif
940    }
941    if (!timerqueue_getnext(&base->active))
942        base->cpu_base->active_bases &= ~(1 << base->index);
943out:
944    timer->state = newstate;
945}
946
947/*
948 * remove hrtimer, called with base lock held
949 */
950static inline int
951remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
952{
953    if (hrtimer_is_queued(timer)) {
954        unsigned long state;
955        int reprogram;
956
957        /*
958         * Remove the timer and force reprogramming when high
959         * resolution mode is active and the timer is on the current
960         * CPU. If we remove a timer on another CPU, reprogramming is
961         * skipped. The interrupt event on this CPU is fired and
962         * reprogramming happens in the interrupt handler. This is a
963         * rare case and less expensive than a smp call.
964         */
965        debug_deactivate(timer);
966        timer_stats_hrtimer_clear_start_info(timer);
967        reprogram = base->cpu_base == &__get_cpu_var(hrtimer_bases);
968        /*
969         * We must preserve the CALLBACK state flag here,
970         * otherwise we could move the timer base in
971         * switch_hrtimer_base.
972         */
973        state = timer->state & HRTIMER_STATE_CALLBACK;
974        __remove_hrtimer(timer, base, state, reprogram);
975        return 1;
976    }
977    return 0;
978}
979
980int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
981        unsigned long delta_ns, const enum hrtimer_mode mode,
982        int wakeup)
983{
984    struct hrtimer_clock_base *base, *new_base;
985    unsigned long flags;
986    int ret, leftmost;
987
988    base = lock_hrtimer_base(timer, &flags);
989
990    /* Remove an active timer from the queue: */
991    ret = remove_hrtimer(timer, base);
992
993    if (mode & HRTIMER_MODE_REL) {
994        tim = ktime_add_safe(tim, base->get_time());
995        /*
996         * CONFIG_TIME_LOW_RES is a temporary way for architectures
997         * to signal that they simply return xtime in
998         * do_gettimeoffset(). In this case we want to round up by
999         * resolution when starting a relative timer, to avoid short
1000         * timeouts. This will go away with the GTOD framework.
1001         */
1002#ifdef CONFIG_TIME_LOW_RES
1003        tim = ktime_add_safe(tim, base->resolution);
1004#endif
1005    }
1006
1007    hrtimer_set_expires_range_ns(timer, tim, delta_ns);
1008
1009    /* Switch the timer base, if necessary: */
1010    new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
1011
1012    timer_stats_hrtimer_set_start_info(timer);
1013
1014    leftmost = enqueue_hrtimer(timer, new_base);
1015
1016    /*
1017     * Only allow reprogramming if the new base is on this CPU.
1018     * (it might still be on another CPU if the timer was pending)
1019     *
1020     * XXX send_remote_softirq() ?
1021     */
1022    if (leftmost && new_base->cpu_base == &__get_cpu_var(hrtimer_bases)
1023        && hrtimer_enqueue_reprogram(timer, new_base)) {
1024        if (wakeup) {
1025            /*
1026             * We need to drop cpu_base->lock to avoid a
1027             * lock ordering issue vs. rq->lock.
1028             */
1029            raw_spin_unlock(&new_base->cpu_base->lock);
1030            raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1031            local_irq_restore(flags);
1032            return ret;
1033        } else {
1034            __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1035        }
1036    }
1037
1038    unlock_hrtimer_base(timer, &flags);
1039
1040    return ret;
1041}
1042
1043/**
1044 * hrtimer_start_range_ns - (re)start an hrtimer on the current CPU
1045 * @timer: the timer to be added
1046 * @tim: expiry time
1047 * @delta_ns: "slack" range for the timer
1048 * @mode: expiry mode: absolute (HRTIMER_MODE_ABS) or
1049 * relative (HRTIMER_MODE_REL)
1050 *
1051 * Returns:
1052 * 0 on success
1053 * 1 when the timer was active
1054 */
1055int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1056        unsigned long delta_ns, const enum hrtimer_mode mode)
1057{
1058    return __hrtimer_start_range_ns(timer, tim, delta_ns, mode, 1);
1059}
1060EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1061
1062/**
1063 * hrtimer_start - (re)start an hrtimer on the current CPU
1064 * @timer: the timer to be added
1065 * @tim: expiry time
1066 * @mode: expiry mode: absolute (HRTIMER_MODE_ABS) or
1067 * relative (HRTIMER_MODE_REL)
1068 *
1069 * Returns:
1070 * 0 on success
1071 * 1 when the timer was active
1072 */
1073int
1074hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
1075{
1076    return __hrtimer_start_range_ns(timer, tim, 0, mode, 1);
1077}
1078EXPORT_SYMBOL_GPL(hrtimer_start);
1079
1080
1081/**
1082 * hrtimer_try_to_cancel - try to deactivate a timer
1083 * @timer: hrtimer to stop
1084 *
1085 * Returns:
1086 * 0 when the timer was not active
1087 * 1 when the timer was active
1088 * -1 when the timer is currently excuting the callback function and
1089 * cannot be stopped
1090 */
1091int hrtimer_try_to_cancel(struct hrtimer *timer)
1092{
1093    struct hrtimer_clock_base *base;
1094    unsigned long flags;
1095    int ret = -1;
1096
1097    base = lock_hrtimer_base(timer, &flags);
1098
1099    if (!hrtimer_callback_running(timer))
1100        ret = remove_hrtimer(timer, base);
1101
1102    unlock_hrtimer_base(timer, &flags);
1103
1104    return ret;
1105
1106}
1107EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1108
1109/**
1110 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1111 * @timer: the timer to be cancelled
1112 *
1113 * Returns:
1114 * 0 when the timer was not active
1115 * 1 when the timer was active
1116 */
1117int hrtimer_cancel(struct hrtimer *timer)
1118{
1119    for (;;) {
1120        int ret = hrtimer_try_to_cancel(timer);
1121
1122        if (ret >= 0)
1123            return ret;
1124        cpu_relax();
1125    }
1126}
1127EXPORT_SYMBOL_GPL(hrtimer_cancel);
1128
1129/**
1130 * hrtimer_get_remaining - get remaining time for the timer
1131 * @timer: the timer to read
1132 */
1133ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
1134{
1135    unsigned long flags;
1136    ktime_t rem;
1137
1138    lock_hrtimer_base(timer, &flags);
1139    rem = hrtimer_expires_remaining(timer);
1140    unlock_hrtimer_base(timer, &flags);
1141
1142    return rem;
1143}
1144EXPORT_SYMBOL_GPL(hrtimer_get_remaining);
1145
1146#ifdef CONFIG_NO_HZ_COMMON
1147/**
1148 * hrtimer_get_next_event - get the time until next expiry event
1149 *
1150 * Returns the delta to the next expiry event or KTIME_MAX if no timer
1151 * is pending.
1152 */
1153ktime_t hrtimer_get_next_event(void)
1154{
1155    struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1156    struct hrtimer_clock_base *base = cpu_base->clock_base;
1157    ktime_t delta, mindelta = { .tv64 = KTIME_MAX };
1158    unsigned long flags;
1159    int i;
1160
1161    raw_spin_lock_irqsave(&cpu_base->lock, flags);
1162
1163    if (!hrtimer_hres_active()) {
1164        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
1165            struct hrtimer *timer;
1166            struct timerqueue_node *next;
1167
1168            next = timerqueue_getnext(&base->active);
1169            if (!next)
1170                continue;
1171
1172            timer = container_of(next, struct hrtimer, node);
1173            delta.tv64 = hrtimer_get_expires_tv64(timer);
1174            delta = ktime_sub(delta, base->get_time());
1175            if (delta.tv64 < mindelta.tv64)
1176                mindelta.tv64 = delta.tv64;
1177        }
1178    }
1179
1180    raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1181
1182    if (mindelta.tv64 < 0)
1183        mindelta.tv64 = 0;
1184    return mindelta;
1185}
1186#endif
1187
1188static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1189               enum hrtimer_mode mode)
1190{
1191    struct hrtimer_cpu_base *cpu_base;
1192    int base;
1193
1194    memset(timer, 0, sizeof(struct hrtimer));
1195
1196    cpu_base = &__raw_get_cpu_var(hrtimer_bases);
1197
1198    if (clock_id == CLOCK_REALTIME && mode != HRTIMER_MODE_ABS)
1199        clock_id = CLOCK_MONOTONIC;
1200
1201    base = hrtimer_clockid_to_base(clock_id);
1202    timer->base = &cpu_base->clock_base[base];
1203    timerqueue_init(&timer->node);
1204
1205#ifdef CONFIG_TIMER_STATS
1206    timer->start_site = NULL;
1207    timer->start_pid = -1;
1208    memset(timer->start_comm, 0, TASK_COMM_LEN);
1209#endif
1210}
1211
1212/**
1213 * hrtimer_init - initialize a timer to the given clock
1214 * @timer: the timer to be initialized
1215 * @clock_id: the clock to be used
1216 * @mode: timer mode abs/rel
1217 */
1218void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1219          enum hrtimer_mode mode)
1220{
1221    debug_init(timer, clock_id, mode);
1222    __hrtimer_init(timer, clock_id, mode);
1223}
1224EXPORT_SYMBOL_GPL(hrtimer_init);
1225
1226/**
1227 * hrtimer_get_res - get the timer resolution for a clock
1228 * @which_clock: which clock to query
1229 * @tp: pointer to timespec variable to store the resolution
1230 *
1231 * Store the resolution of the clock selected by @which_clock in the
1232 * variable pointed to by @tp.
1233 */
1234int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
1235{
1236    struct hrtimer_cpu_base *cpu_base;
1237    int base = hrtimer_clockid_to_base(which_clock);
1238
1239    cpu_base = &__raw_get_cpu_var(hrtimer_bases);
1240    *tp = ktime_to_timespec(cpu_base->clock_base[base].resolution);
1241
1242    return 0;
1243}
1244EXPORT_SYMBOL_GPL(hrtimer_get_res);
1245
1246static void __run_hrtimer(struct hrtimer *timer, ktime_t *now)
1247{
1248    struct hrtimer_clock_base *base = timer->base;
1249    struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1250    enum hrtimer_restart (*fn)(struct hrtimer *);
1251    int restart;
1252
1253    WARN_ON(!irqs_disabled());
1254
1255    debug_deactivate(timer);
1256    __remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0);
1257    timer_stats_account_hrtimer(timer);
1258    fn = timer->function;
1259
1260    /*
1261     * Because we run timers from hardirq context, there is no chance
1262     * they get migrated to another cpu, therefore its safe to unlock
1263     * the timer base.
1264     */
1265    raw_spin_unlock(&cpu_base->lock);
1266    trace_hrtimer_expire_entry(timer, now);
1267    restart = fn(timer);
1268    trace_hrtimer_expire_exit(timer);
1269    raw_spin_lock(&cpu_base->lock);
1270
1271    /*
1272     * Note: We clear the CALLBACK bit after enqueue_hrtimer and
1273     * we do not reprogramm the event hardware. Happens either in
1274     * hrtimer_start_range_ns() or in hrtimer_interrupt()
1275     */
1276    if (restart != HRTIMER_NORESTART) {
1277        BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
1278        enqueue_hrtimer(timer, base);
1279    }
1280
1281    WARN_ON_ONCE(!(timer->state & HRTIMER_STATE_CALLBACK));
1282
1283    timer->state &= ~HRTIMER_STATE_CALLBACK;
1284}
1285
1286#ifdef CONFIG_HIGH_RES_TIMERS
1287
1288/*
1289 * High resolution timer interrupt
1290 * Called with interrupts disabled
1291 */
1292void hrtimer_interrupt(struct clock_event_device *dev)
1293{
1294    struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1295    ktime_t expires_next, now, entry_time, delta;
1296    int i, retries = 0;
1297
1298    BUG_ON(!cpu_base->hres_active);
1299    cpu_base->nr_events++;
1300    dev->next_event.tv64 = KTIME_MAX;
1301
1302    raw_spin_lock(&cpu_base->lock);
1303    entry_time = now = hrtimer_update_base(cpu_base);
1304retry:
1305    expires_next.tv64 = KTIME_MAX;
1306    /*
1307     * We set expires_next to KTIME_MAX here with cpu_base->lock
1308     * held to prevent that a timer is enqueued in our queue via
1309     * the migration code. This does not affect enqueueing of
1310     * timers which run their callback and need to be requeued on
1311     * this CPU.
1312     */
1313    cpu_base->expires_next.tv64 = KTIME_MAX;
1314
1315    for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1316        struct hrtimer_clock_base *base;
1317        struct timerqueue_node *node;
1318        ktime_t basenow;
1319
1320        if (!(cpu_base->active_bases & (1 << i)))
1321            continue;
1322
1323        base = cpu_base->clock_base + i;
1324        basenow = ktime_add(now, base->offset);
1325
1326        while ((node = timerqueue_getnext(&base->active))) {
1327            struct hrtimer *timer;
1328
1329            timer = container_of(node, struct hrtimer, node);
1330
1331            /*
1332             * The immediate goal for using the softexpires is
1333             * minimizing wakeups, not running timers at the
1334             * earliest interrupt after their soft expiration.
1335             * This allows us to avoid using a Priority Search
1336             * Tree, which can answer a stabbing querry for
1337             * overlapping intervals and instead use the simple
1338             * BST we already have.
1339             * We don't add extra wakeups by delaying timers that
1340             * are right-of a not yet expired timer, because that
1341             * timer will have to trigger a wakeup anyway.
1342             */
1343
1344            if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer)) {
1345                ktime_t expires;
1346
1347                expires = ktime_sub(hrtimer_get_expires(timer),
1348                            base->offset);
1349                if (expires.tv64 < 0)
1350                    expires.tv64 = KTIME_MAX;
1351                if (expires.tv64 < expires_next.tv64)
1352                    expires_next = expires;
1353                break;
1354            }
1355
1356            __run_hrtimer(timer, &basenow);
1357        }
1358    }
1359
1360    /*
1361     * Store the new expiry value so the migration code can verify
1362     * against it.
1363     */
1364    cpu_base->expires_next = expires_next;
1365    raw_spin_unlock(&cpu_base->lock);
1366
1367    /* Reprogramming necessary ? */
1368    if (expires_next.tv64 == KTIME_MAX ||
1369        !tick_program_event(expires_next, 0)) {
1370        cpu_base->hang_detected = 0;
1371        return;
1372    }
1373
1374    /*
1375     * The next timer was already expired due to:
1376     * - tracing
1377     * - long lasting callbacks
1378     * - being scheduled away when running in a VM
1379     *
1380     * We need to prevent that we loop forever in the hrtimer
1381     * interrupt routine. We give it 3 attempts to avoid
1382     * overreacting on some spurious event.
1383     *
1384     * Acquire base lock for updating the offsets and retrieving
1385     * the current time.
1386     */
1387    raw_spin_lock(&cpu_base->lock);
1388    now = hrtimer_update_base(cpu_base);
1389    cpu_base->nr_retries++;
1390    if (++retries < 3)
1391        goto retry;
1392    /*
1393     * Give the system a chance to do something else than looping
1394     * here. We stored the entry time, so we know exactly how long
1395     * we spent here. We schedule the next event this amount of
1396     * time away.
1397     */
1398    cpu_base->nr_hangs++;
1399    cpu_base->hang_detected = 1;
1400    raw_spin_unlock(&cpu_base->lock);
1401    delta = ktime_sub(now, entry_time);
1402    if (delta.tv64 > cpu_base->max_hang_time.tv64)
1403        cpu_base->max_hang_time = delta;
1404    /*
1405     * Limit it to a sensible value as we enforce a longer
1406     * delay. Give the CPU at least 100ms to catch up.
1407     */
1408    if (delta.tv64 > 100 * NSEC_PER_MSEC)
1409        expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1410    else
1411        expires_next = ktime_add(now, delta);
1412    tick_program_event(expires_next, 1);
1413    printk_once(KERN_WARNING "hrtimer: interrupt took %llu ns\n",
1414            ktime_to_ns(delta));
1415}
1416
1417/*
1418 * local version of hrtimer_peek_ahead_timers() called with interrupts
1419 * disabled.
1420 */
1421static void __hrtimer_peek_ahead_timers(void)
1422{
1423    struct tick_device *td;
1424
1425    if (!hrtimer_hres_active())
1426        return;
1427
1428    td = &__get_cpu_var(tick_cpu_device);
1429    if (td && td->evtdev)
1430        hrtimer_interrupt(td->evtdev);
1431}
1432
1433/**
1434 * hrtimer_peek_ahead_timers -- run soft-expired timers now
1435 *
1436 * hrtimer_peek_ahead_timers will peek at the timer queue of
1437 * the current cpu and check if there are any timers for which
1438 * the soft expires time has passed. If any such timers exist,
1439 * they are run immediately and then removed from the timer queue.
1440 *
1441 */
1442void hrtimer_peek_ahead_timers(void)
1443{
1444    unsigned long flags;
1445
1446    local_irq_save(flags);
1447    __hrtimer_peek_ahead_timers();
1448    local_irq_restore(flags);
1449}
1450
1451static void run_hrtimer_softirq(struct softirq_action *h)
1452{
1453    hrtimer_peek_ahead_timers();
1454}
1455
1456#else /* CONFIG_HIGH_RES_TIMERS */
1457
1458static inline void __hrtimer_peek_ahead_timers(void) { }
1459
1460#endif /* !CONFIG_HIGH_RES_TIMERS */
1461
1462/*
1463 * Called from timer softirq every jiffy, expire hrtimers:
1464 *
1465 * For HRT its the fall back code to run the softirq in the timer
1466 * softirq context in case the hrtimer initialization failed or has
1467 * not been done yet.
1468 */
1469void hrtimer_run_pending(void)
1470{
1471    if (hrtimer_hres_active())
1472        return;
1473
1474    /*
1475     * This _is_ ugly: We have to check in the softirq context,
1476     * whether we can switch to highres and / or nohz mode. The
1477     * clocksource switch happens in the timer interrupt with
1478     * xtime_lock held. Notification from there only sets the
1479     * check bit in the tick_oneshot code, otherwise we might
1480     * deadlock vs. xtime_lock.
1481     */
1482    if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
1483        hrtimer_switch_to_hres();
1484}
1485
1486/*
1487 * Called from hardirq context every jiffy
1488 */
1489void hrtimer_run_queues(void)
1490{
1491    struct timerqueue_node *node;
1492    struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1493    struct hrtimer_clock_base *base;
1494    int index, gettime = 1;
1495
1496    if (hrtimer_hres_active())
1497        return;
1498
1499    for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {
1500        base = &cpu_base->clock_base[index];
1501        if (!timerqueue_getnext(&base->active))
1502            continue;
1503
1504        if (gettime) {
1505            hrtimer_get_softirq_time(cpu_base);
1506            gettime = 0;
1507        }
1508
1509        raw_spin_lock(&cpu_base->lock);
1510
1511        while ((node = timerqueue_getnext(&base->active))) {
1512            struct hrtimer *timer;
1513
1514            timer = container_of(node, struct hrtimer, node);
1515            if (base->softirq_time.tv64 <=
1516                    hrtimer_get_expires_tv64(timer))
1517                break;
1518
1519            __run_hrtimer(timer, &base->softirq_time);
1520        }
1521        raw_spin_unlock(&cpu_base->lock);
1522    }
1523}
1524
1525/*
1526 * Sleep related functions:
1527 */
1528static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1529{
1530    struct hrtimer_sleeper *t =
1531        container_of(timer, struct hrtimer_sleeper, timer);
1532    struct task_struct *task = t->task;
1533
1534    t->task = NULL;
1535    if (task)
1536        wake_up_process(task);
1537
1538    return HRTIMER_NORESTART;
1539}
1540
1541void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task)
1542{
1543    sl->timer.function = hrtimer_wakeup;
1544    sl->task = task;
1545}
1546EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
1547
1548static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
1549{
1550    hrtimer_init_sleeper(t, current);
1551
1552    do {
1553        set_current_state(TASK_INTERRUPTIBLE);
1554        hrtimer_start_expires(&t->timer, mode);
1555        if (!hrtimer_active(&t->timer))
1556            t->task = NULL;
1557
1558        if (likely(t->task))
1559            freezable_schedule();
1560
1561        hrtimer_cancel(&t->timer);
1562        mode = HRTIMER_MODE_ABS;
1563
1564    } while (t->task && !signal_pending(current));
1565
1566    __set_current_state(TASK_RUNNING);
1567
1568    return t->task == NULL;
1569}
1570
1571static int update_rmtp(struct hrtimer *timer, struct timespec __user *rmtp)
1572{
1573    struct timespec rmt;
1574    ktime_t rem;
1575
1576    rem = hrtimer_expires_remaining(timer);
1577    if (rem.tv64 <= 0)
1578        return 0;
1579    rmt = ktime_to_timespec(rem);
1580
1581    if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
1582        return -EFAULT;
1583
1584    return 1;
1585}
1586
1587long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
1588{
1589    struct hrtimer_sleeper t;
1590    struct timespec __user *rmtp;
1591    int ret = 0;
1592
1593    hrtimer_init_on_stack(&t.timer, restart->nanosleep.clockid,
1594                HRTIMER_MODE_ABS);
1595    hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
1596
1597    if (do_nanosleep(&t, HRTIMER_MODE_ABS))
1598        goto out;
1599
1600    rmtp = restart->nanosleep.rmtp;
1601    if (rmtp) {
1602        ret = update_rmtp(&t.timer, rmtp);
1603        if (ret <= 0)
1604            goto out;
1605    }
1606
1607    /* The other values in restart are already filled in */
1608    ret = -ERESTART_RESTARTBLOCK;
1609out:
1610    destroy_hrtimer_on_stack(&t.timer);
1611    return ret;
1612}
1613
1614long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
1615               const enum hrtimer_mode mode, const clockid_t clockid)
1616{
1617    struct restart_block *restart;
1618    struct hrtimer_sleeper t;
1619    int ret = 0;
1620    unsigned long slack;
1621
1622    slack = current->timer_slack_ns;
1623    if (dl_task(current) || rt_task(current))
1624        slack = 0;
1625
1626    hrtimer_init_on_stack(&t.timer, clockid, mode);
1627    hrtimer_set_expires_range_ns(&t.timer, timespec_to_ktime(*rqtp), slack);
1628    if (do_nanosleep(&t, mode))
1629        goto out;
1630
1631    /* Absolute timers do not update the rmtp value and restart: */
1632    if (mode == HRTIMER_MODE_ABS) {
1633        ret = -ERESTARTNOHAND;
1634        goto out;
1635    }
1636
1637    if (rmtp) {
1638        ret = update_rmtp(&t.timer, rmtp);
1639        if (ret <= 0)
1640            goto out;
1641    }
1642
1643    restart = &current_thread_info()->restart_block;
1644    restart->fn = hrtimer_nanosleep_restart;
1645    restart->nanosleep.clockid = t.timer.base->clockid;
1646    restart->nanosleep.rmtp = rmtp;
1647    restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
1648
1649    ret = -ERESTART_RESTARTBLOCK;
1650out:
1651    destroy_hrtimer_on_stack(&t.timer);
1652    return ret;
1653}
1654
1655SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
1656        struct timespec __user *, rmtp)
1657{
1658    struct timespec tu;
1659
1660    if (copy_from_user(&tu, rqtp, sizeof(tu)))
1661        return -EFAULT;
1662
1663    if (!timespec_valid(&tu))
1664        return -EINVAL;
1665
1666    return hrtimer_nanosleep(&tu, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
1667}
1668
1669/*
1670 * Functions related to boot-time initialization:
1671 */
1672static void init_hrtimers_cpu(int cpu)
1673{
1674    struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
1675    int i;
1676
1677    for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1678        cpu_base->clock_base[i].cpu_base = cpu_base;
1679        timerqueue_init_head(&cpu_base->clock_base[i].active);
1680    }
1681
1682    hrtimer_init_hres(cpu_base);
1683}
1684
1685#ifdef CONFIG_HOTPLUG_CPU
1686
1687static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
1688                struct hrtimer_clock_base *new_base)
1689{
1690    struct hrtimer *timer;
1691    struct timerqueue_node *node;
1692
1693    while ((node = timerqueue_getnext(&old_base->active))) {
1694        timer = container_of(node, struct hrtimer, node);
1695        BUG_ON(hrtimer_callback_running(timer));
1696        debug_deactivate(timer);
1697
1698        /*
1699         * Mark it as STATE_MIGRATE not INACTIVE otherwise the
1700         * timer could be seen as !active and just vanish away
1701         * under us on another CPU
1702         */
1703        __remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0);
1704        timer->base = new_base;
1705        /*
1706         * Enqueue the timers on the new cpu. This does not
1707         * reprogram the event device in case the timer
1708         * expires before the earliest on this CPU, but we run
1709         * hrtimer_interrupt after we migrated everything to
1710         * sort out already expired timers and reprogram the
1711         * event device.
1712         */
1713        enqueue_hrtimer(timer, new_base);
1714
1715        /* Clear the migration state bit */
1716        timer->state &= ~HRTIMER_STATE_MIGRATE;
1717    }
1718}
1719
1720static void migrate_hrtimers(int scpu)
1721{
1722    struct hrtimer_cpu_base *old_base, *new_base;
1723    int i;
1724
1725    BUG_ON(cpu_online(scpu));
1726    tick_cancel_sched_timer(scpu);
1727
1728    local_irq_disable();
1729    old_base = &per_cpu(hrtimer_bases, scpu);
1730    new_base = &__get_cpu_var(hrtimer_bases);
1731    /*
1732     * The caller is globally serialized and nobody else
1733     * takes two locks at once, deadlock is not possible.
1734     */
1735    raw_spin_lock(&new_base->lock);
1736    raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1737
1738    for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1739        migrate_hrtimer_list(&old_base->clock_base[i],
1740                     &new_base->clock_base[i]);
1741    }
1742
1743    raw_spin_unlock(&old_base->lock);
1744    raw_spin_unlock(&new_base->lock);
1745
1746    /* Check, if we got expired work to do */
1747    __hrtimer_peek_ahead_timers();
1748    local_irq_enable();
1749}
1750
1751#endif /* CONFIG_HOTPLUG_CPU */
1752
1753static int hrtimer_cpu_notify(struct notifier_block *self,
1754                    unsigned long action, void *hcpu)
1755{
1756    int scpu = (long)hcpu;
1757
1758    switch (action) {
1759
1760    case CPU_UP_PREPARE:
1761    case CPU_UP_PREPARE_FROZEN:
1762        init_hrtimers_cpu(scpu);
1763        break;
1764
1765#ifdef CONFIG_HOTPLUG_CPU
1766    case CPU_DYING:
1767    case CPU_DYING_FROZEN:
1768        clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DYING, &scpu);
1769        break;
1770    case CPU_DEAD:
1771    case CPU_DEAD_FROZEN:
1772    {
1773        clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu);
1774        migrate_hrtimers(scpu);
1775        break;
1776    }
1777#endif
1778
1779    default:
1780        break;
1781    }
1782
1783    return NOTIFY_OK;
1784}
1785
1786static struct notifier_block hrtimers_nb = {
1787    .notifier_call = hrtimer_cpu_notify,
1788};
1789
1790void __init hrtimers_init(void)
1791{
1792    hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
1793              (void *)(long)smp_processor_id());
1794    register_cpu_notifier(&hrtimers_nb);
1795#ifdef CONFIG_HIGH_RES_TIMERS
1796    open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq);
1797#endif
1798}
1799
1800/**
1801 * schedule_hrtimeout_range_clock - sleep until timeout
1802 * @expires: timeout value (ktime_t)
1803 * @delta: slack in expires timeout (ktime_t)
1804 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1805 * @clock: timer clock, CLOCK_MONOTONIC or CLOCK_REALTIME
1806 */
1807int __sched
1808schedule_hrtimeout_range_clock(ktime_t *expires, unsigned long delta,
1809                   const enum hrtimer_mode mode, int clock)
1810{
1811    struct hrtimer_sleeper t;
1812
1813    /*
1814     * Optimize when a zero timeout value is given. It does not
1815     * matter whether this is an absolute or a relative time.
1816     */
1817    if (expires && !expires->tv64) {
1818        __set_current_state(TASK_RUNNING);
1819        return 0;
1820    }
1821
1822    /*
1823     * A NULL parameter means "infinite"
1824     */
1825    if (!expires) {
1826        schedule();
1827        __set_current_state(TASK_RUNNING);
1828        return -EINTR;
1829    }
1830
1831    hrtimer_init_on_stack(&t.timer, clock, mode);
1832    hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
1833
1834    hrtimer_init_sleeper(&t, current);
1835
1836    hrtimer_start_expires(&t.timer, mode);
1837    if (!hrtimer_active(&t.timer))
1838        t.task = NULL;
1839
1840    if (likely(t.task))
1841        schedule();
1842
1843    hrtimer_cancel(&t.timer);
1844    destroy_hrtimer_on_stack(&t.timer);
1845
1846    __set_current_state(TASK_RUNNING);
1847
1848    return !t.task ? 0 : -EINTR;
1849}
1850
1851/**
1852 * schedule_hrtimeout_range - sleep until timeout
1853 * @expires: timeout value (ktime_t)
1854 * @delta: slack in expires timeout (ktime_t)
1855 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1856 *
1857 * Make the current task sleep until the given expiry time has
1858 * elapsed. The routine will return immediately unless
1859 * the current task state has been set (see set_current_state()).
1860 *
1861 * The @delta argument gives the kernel the freedom to schedule the
1862 * actual wakeup to a time that is both power and performance friendly.
1863 * The kernel give the normal best effort behavior for "@expires+@delta",
1864 * but may decide to fire the timer earlier, but no earlier than @expires.
1865 *
1866 * You can set the task state as follows -
1867 *
1868 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1869 * pass before the routine returns.
1870 *
1871 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1872 * delivered to the current task.
1873 *
1874 * The current task state is guaranteed to be TASK_RUNNING when this
1875 * routine returns.
1876 *
1877 * Returns 0 when the timer has expired otherwise -EINTR
1878 */
1879int __sched schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
1880                     const enum hrtimer_mode mode)
1881{
1882    return schedule_hrtimeout_range_clock(expires, delta, mode,
1883                          CLOCK_MONOTONIC);
1884}
1885EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
1886
1887/**
1888 * schedule_hrtimeout - sleep until timeout
1889 * @expires: timeout value (ktime_t)
1890 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1891 *
1892 * Make the current task sleep until the given expiry time has
1893 * elapsed. The routine will return immediately unless
1894 * the current task state has been set (see set_current_state()).
1895 *
1896 * You can set the task state as follows -
1897 *
1898 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1899 * pass before the routine returns.
1900 *
1901 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1902 * delivered to the current task.
1903 *
1904 * The current task state is guaranteed to be TASK_RUNNING when this
1905 * routine returns.
1906 *
1907 * Returns 0 when the timer has expired otherwise -EINTR
1908 */
1909int __sched schedule_hrtimeout(ktime_t *expires,
1910                   const enum hrtimer_mode mode)
1911{
1912    return schedule_hrtimeout_range(expires, 0, mode);
1913}
1914EXPORT_SYMBOL_GPL(schedule_hrtimeout);
1915

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