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

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