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 __this_cpu_read(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        struct timerqueue_node *next;
520
521        next = timerqueue_getnext(&base->active);
522        if (!next)
523            continue;
524        timer = container_of(next, struct hrtimer, node);
525
526        expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
527        /*
528         * clock_was_set() has changed base->offset so the
529         * result might be negative. Fix it up to prevent a
530         * false positive in clockevents_program_event()
531         */
532        if (expires.tv64 < 0)
533            expires.tv64 = 0;
534        if (expires.tv64 < expires_next.tv64)
535            expires_next = expires;
536    }
537
538    if (skip_equal && expires_next.tv64 == cpu_base->expires_next.tv64)
539        return;
540
541    cpu_base->expires_next.tv64 = expires_next.tv64;
542
543    if (cpu_base->expires_next.tv64 != KTIME_MAX)
544        tick_program_event(cpu_base->expires_next, 1);
545}
546
547/*
548 * Shared reprogramming for clock_realtime and clock_monotonic
549 *
550 * When a timer is enqueued and expires earlier than the already enqueued
551 * timers, we have to check, whether it expires earlier than the timer for
552 * which the clock event device was armed.
553 *
554 * Called with interrupts disabled and base->cpu_base.lock held
555 */
556static int hrtimer_reprogram(struct hrtimer *timer,
557                 struct hrtimer_clock_base *base)
558{
559    struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
560    ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
561    int res;
562
563    WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
564
565    /*
566     * When the callback is running, we do not reprogram the clock event
567     * device. The timer callback is either running on a different CPU or
568     * the callback is executed in the hrtimer_interrupt context. The
569     * reprogramming is handled either by the softirq, which called the
570     * callback or at the end of the hrtimer_interrupt.
571     */
572    if (hrtimer_callback_running(timer))
573        return 0;
574
575    /*
576     * CLOCK_REALTIME timer might be requested with an absolute
577     * expiry time which is less than base->offset. Nothing wrong
578     * about that, just avoid to call into the tick code, which
579     * has now objections against negative expiry values.
580     */
581    if (expires.tv64 < 0)
582        return -ETIME;
583
584    if (expires.tv64 >= cpu_base->expires_next.tv64)
585        return 0;
586
587    /*
588     * If a hang was detected in the last timer interrupt then we
589     * do not schedule a timer which is earlier than the expiry
590     * which we enforced in the hang detection. We want the system
591     * to make progress.
592     */
593    if (cpu_base->hang_detected)
594        return 0;
595
596    /*
597     * Clockevents returns -ETIME, when the event was in the past.
598     */
599    res = tick_program_event(expires, 0);
600    if (!IS_ERR_VALUE(res))
601        cpu_base->expires_next = expires;
602    return res;
603}
604
605
606/*
607 * Retrigger next event is called after clock was set
608 *
609 * Called with interrupts disabled via on_each_cpu()
610 */
611static void retrigger_next_event(void *arg)
612{
613    struct hrtimer_cpu_base *base;
614    struct timespec realtime_offset, wtm;
615    unsigned long seq;
616
617    if (!hrtimer_hres_active())
618        return;
619
620    do {
621        seq = read_seqbegin(&xtime_lock);
622        wtm = __get_wall_to_monotonic();
623    } while (read_seqretry(&xtime_lock, seq));
624    set_normalized_timespec(&realtime_offset, -wtm.tv_sec, -wtm.tv_nsec);
625
626    base = &__get_cpu_var(hrtimer_bases);
627
628    /* Adjust CLOCK_REALTIME offset */
629    raw_spin_lock(&base->lock);
630    base->clock_base[CLOCK_REALTIME].offset =
631        timespec_to_ktime(realtime_offset);
632
633    hrtimer_force_reprogram(base, 0);
634    raw_spin_unlock(&base->lock);
635}
636
637/*
638 * Clock realtime was set
639 *
640 * Change the offset of the realtime clock vs. the monotonic
641 * clock.
642 *
643 * We might have to reprogram the high resolution timer interrupt. On
644 * SMP we call the architecture specific code to retrigger _all_ high
645 * resolution timer interrupts. On UP we just disable interrupts and
646 * call the high resolution interrupt code.
647 */
648void clock_was_set(void)
649{
650    /* Retrigger the CPU local events everywhere */
651    on_each_cpu(retrigger_next_event, NULL, 1);
652}
653
654/*
655 * During resume we might have to reprogram the high resolution timer
656 * interrupt (on the local CPU):
657 */
658void hres_timers_resume(void)
659{
660    WARN_ONCE(!irqs_disabled(),
661          KERN_INFO "hres_timers_resume() called with IRQs enabled!");
662
663    retrigger_next_event(NULL);
664}
665
666/*
667 * Initialize the high resolution related parts of cpu_base
668 */
669static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base)
670{
671    base->expires_next.tv64 = KTIME_MAX;
672    base->hres_active = 0;
673}
674
675/*
676 * Initialize the high resolution related parts of a hrtimer
677 */
678static inline void hrtimer_init_timer_hres(struct hrtimer *timer)
679{
680}
681
682
683/*
684 * When High resolution timers are active, try to reprogram. Note, that in case
685 * the state has HRTIMER_STATE_CALLBACK set, no reprogramming and no expiry
686 * check happens. The timer gets enqueued into the rbtree. The reprogramming
687 * and expiry check is done in the hrtimer_interrupt or in the softirq.
688 */
689static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
690                        struct hrtimer_clock_base *base,
691                        int wakeup)
692{
693    if (base->cpu_base->hres_active && hrtimer_reprogram(timer, base)) {
694        if (wakeup) {
695            raw_spin_unlock(&base->cpu_base->lock);
696            raise_softirq_irqoff(HRTIMER_SOFTIRQ);
697            raw_spin_lock(&base->cpu_base->lock);
698        } else
699            __raise_softirq_irqoff(HRTIMER_SOFTIRQ);
700
701        return 1;
702    }
703
704    return 0;
705}
706
707/*
708 * Switch to high resolution mode
709 */
710static int hrtimer_switch_to_hres(void)
711{
712    int cpu = smp_processor_id();
713    struct hrtimer_cpu_base *base = &per_cpu(hrtimer_bases, cpu);
714    unsigned long flags;
715
716    if (base->hres_active)
717        return 1;
718
719    local_irq_save(flags);
720
721    if (tick_init_highres()) {
722        local_irq_restore(flags);
723        printk(KERN_WARNING "Could not switch to high resolution "
724                    "mode on CPU %d\n", cpu);
725        return 0;
726    }
727    base->hres_active = 1;
728    base->clock_base[CLOCK_REALTIME].resolution = KTIME_HIGH_RES;
729    base->clock_base[CLOCK_MONOTONIC].resolution = KTIME_HIGH_RES;
730
731    tick_setup_sched_timer();
732
733    /* "Retrigger" the interrupt to get things going */
734    retrigger_next_event(NULL);
735    local_irq_restore(flags);
736    return 1;
737}
738
739#else
740
741static inline int hrtimer_hres_active(void) { return 0; }
742static inline int hrtimer_is_hres_enabled(void) { return 0; }
743static inline int hrtimer_switch_to_hres(void) { return 0; }
744static inline void
745hrtimer_force_reprogram(struct hrtimer_cpu_base *base, int skip_equal) { }
746static inline int hrtimer_enqueue_reprogram(struct hrtimer *timer,
747                        struct hrtimer_clock_base *base,
748                        int wakeup)
749{
750    return 0;
751}
752static inline void hrtimer_init_hres(struct hrtimer_cpu_base *base) { }
753static inline void hrtimer_init_timer_hres(struct hrtimer *timer) { }
754
755#endif /* CONFIG_HIGH_RES_TIMERS */
756
757static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
758{
759#ifdef CONFIG_TIMER_STATS
760    if (timer->start_site)
761        return;
762    timer->start_site = __builtin_return_address(0);
763    memcpy(timer->start_comm, current->comm, TASK_COMM_LEN);
764    timer->start_pid = current->pid;
765#endif
766}
767
768static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
769{
770#ifdef CONFIG_TIMER_STATS
771    timer->start_site = NULL;
772#endif
773}
774
775static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
776{
777#ifdef CONFIG_TIMER_STATS
778    if (likely(!timer_stats_active))
779        return;
780    timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
781                 timer->function, timer->start_comm, 0);
782#endif
783}
784
785/*
786 * Counterpart to lock_hrtimer_base above:
787 */
788static inline
789void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
790{
791    raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
792}
793
794/**
795 * hrtimer_forward - forward the timer expiry
796 * @timer: hrtimer to forward
797 * @now: forward past this time
798 * @interval: the interval to forward
799 *
800 * Forward the timer expiry so it will expire in the future.
801 * Returns the number of overruns.
802 */
803u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
804{
805    u64 orun = 1;
806    ktime_t delta;
807
808    delta = ktime_sub(now, hrtimer_get_expires(timer));
809
810    if (delta.tv64 < 0)
811        return 0;
812
813    if (interval.tv64 < timer->base->resolution.tv64)
814        interval.tv64 = timer->base->resolution.tv64;
815
816    if (unlikely(delta.tv64 >= interval.tv64)) {
817        s64 incr = ktime_to_ns(interval);
818
819        orun = ktime_divns(delta, incr);
820        hrtimer_add_expires_ns(timer, incr * orun);
821        if (hrtimer_get_expires_tv64(timer) > now.tv64)
822            return orun;
823        /*
824         * This (and the ktime_add() below) is the
825         * correction for exact:
826         */
827        orun++;
828    }
829    hrtimer_add_expires(timer, interval);
830
831    return orun;
832}
833EXPORT_SYMBOL_GPL(hrtimer_forward);
834
835/*
836 * enqueue_hrtimer - internal function to (re)start a timer
837 *
838 * The timer is inserted in expiry order. Insertion into the
839 * red black tree is O(log(n)). Must hold the base lock.
840 *
841 * Returns 1 when the new timer is the leftmost timer in the tree.
842 */
843static int enqueue_hrtimer(struct hrtimer *timer,
844               struct hrtimer_clock_base *base)
845{
846    debug_activate(timer);
847
848    timerqueue_add(&base->active, &timer->node);
849
850    /*
851     * HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the
852     * state of a possibly running callback.
853     */
854    timer->state |= HRTIMER_STATE_ENQUEUED;
855
856    return (&timer->node == base->active.next);
857}
858
859/*
860 * __remove_hrtimer - internal function to remove a timer
861 *
862 * Caller must hold the base lock.
863 *
864 * High resolution timer mode reprograms the clock event device when the
865 * timer is the one which expires next. The caller can disable this by setting
866 * reprogram to zero. This is useful, when the context does a reprogramming
867 * anyway (e.g. timer interrupt)
868 */
869static void __remove_hrtimer(struct hrtimer *timer,
870                 struct hrtimer_clock_base *base,
871                 unsigned long newstate, int reprogram)
872{
873    if (!(timer->state & HRTIMER_STATE_ENQUEUED))
874        goto out;
875
876    if (&timer->node == timerqueue_getnext(&base->active)) {
877#ifdef CONFIG_HIGH_RES_TIMERS
878        /* Reprogram the clock event device. if enabled */
879        if (reprogram && hrtimer_hres_active()) {
880            ktime_t expires;
881
882            expires = ktime_sub(hrtimer_get_expires(timer),
883                        base->offset);
884            if (base->cpu_base->expires_next.tv64 == expires.tv64)
885                hrtimer_force_reprogram(base->cpu_base, 1);
886        }
887#endif
888    }
889    timerqueue_del(&base->active, &timer->node);
890out:
891    timer->state = newstate;
892}
893
894/*
895 * remove hrtimer, called with base lock held
896 */
897static inline int
898remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base)
899{
900    if (hrtimer_is_queued(timer)) {
901        unsigned long state;
902        int reprogram;
903
904        /*
905         * Remove the timer and force reprogramming when high
906         * resolution mode is active and the timer is on the current
907         * CPU. If we remove a timer on another CPU, reprogramming is
908         * skipped. The interrupt event on this CPU is fired and
909         * reprogramming happens in the interrupt handler. This is a
910         * rare case and less expensive than a smp call.
911         */
912        debug_deactivate(timer);
913        timer_stats_hrtimer_clear_start_info(timer);
914        reprogram = base->cpu_base == &__get_cpu_var(hrtimer_bases);
915        /*
916         * We must preserve the CALLBACK state flag here,
917         * otherwise we could move the timer base in
918         * switch_hrtimer_base.
919         */
920        state = timer->state & HRTIMER_STATE_CALLBACK;
921        __remove_hrtimer(timer, base, state, reprogram);
922        return 1;
923    }
924    return 0;
925}
926
927int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
928        unsigned long delta_ns, const enum hrtimer_mode mode,
929        int wakeup)
930{
931    struct hrtimer_clock_base *base, *new_base;
932    unsigned long flags;
933    int ret, leftmost;
934
935    base = lock_hrtimer_base(timer, &flags);
936
937    /* Remove an active timer from the queue: */
938    ret = remove_hrtimer(timer, base);
939
940    /* Switch the timer base, if necessary: */
941    new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
942
943    if (mode & HRTIMER_MODE_REL) {
944        tim = ktime_add_safe(tim, new_base->get_time());
945        /*
946         * CONFIG_TIME_LOW_RES is a temporary way for architectures
947         * to signal that they simply return xtime in
948         * do_gettimeoffset(). In this case we want to round up by
949         * resolution when starting a relative timer, to avoid short
950         * timeouts. This will go away with the GTOD framework.
951         */
952#ifdef CONFIG_TIME_LOW_RES
953        tim = ktime_add_safe(tim, base->resolution);
954#endif
955    }
956
957    hrtimer_set_expires_range_ns(timer, tim, delta_ns);
958
959    timer_stats_hrtimer_set_start_info(timer);
960
961    leftmost = enqueue_hrtimer(timer, new_base);
962
963    /*
964     * Only allow reprogramming if the new base is on this CPU.
965     * (it might still be on another CPU if the timer was pending)
966     *
967     * XXX send_remote_softirq() ?
968     */
969    if (leftmost && new_base->cpu_base == &__get_cpu_var(hrtimer_bases))
970        hrtimer_enqueue_reprogram(timer, new_base, wakeup);
971
972    unlock_hrtimer_base(timer, &flags);
973
974    return ret;
975}
976
977/**
978 * hrtimer_start_range_ns - (re)start an hrtimer on the current CPU
979 * @timer: the timer to be added
980 * @tim: expiry time
981 * @delta_ns: "slack" range for the timer
982 * @mode: expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
983 *
984 * Returns:
985 * 0 on success
986 * 1 when the timer was active
987 */
988int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
989        unsigned long delta_ns, const enum hrtimer_mode mode)
990{
991    return __hrtimer_start_range_ns(timer, tim, delta_ns, mode, 1);
992}
993EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
994
995/**
996 * hrtimer_start - (re)start an hrtimer on the current CPU
997 * @timer: the timer to be added
998 * @tim: expiry time
999 * @mode: expiry mode: absolute (HRTIMER_ABS) or relative (HRTIMER_REL)
1000 *
1001 * Returns:
1002 * 0 on success
1003 * 1 when the timer was active
1004 */
1005int
1006hrtimer_start(struct hrtimer *timer, ktime_t tim, const enum hrtimer_mode mode)
1007{
1008    return __hrtimer_start_range_ns(timer, tim, 0, mode, 1);
1009}
1010EXPORT_SYMBOL_GPL(hrtimer_start);
1011
1012
1013/**
1014 * hrtimer_try_to_cancel - try to deactivate a timer
1015 * @timer: hrtimer to stop
1016 *
1017 * Returns:
1018 * 0 when the timer was not active
1019 * 1 when the timer was active
1020 * -1 when the timer is currently excuting the callback function and
1021 * cannot be stopped
1022 */
1023int hrtimer_try_to_cancel(struct hrtimer *timer)
1024{
1025    struct hrtimer_clock_base *base;
1026    unsigned long flags;
1027    int ret = -1;
1028
1029    base = lock_hrtimer_base(timer, &flags);
1030
1031    if (!hrtimer_callback_running(timer))
1032        ret = remove_hrtimer(timer, base);
1033
1034    unlock_hrtimer_base(timer, &flags);
1035
1036    return ret;
1037
1038}
1039EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1040
1041/**
1042 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1043 * @timer: the timer to be cancelled
1044 *
1045 * Returns:
1046 * 0 when the timer was not active
1047 * 1 when the timer was active
1048 */
1049int hrtimer_cancel(struct hrtimer *timer)
1050{
1051    for (;;) {
1052        int ret = hrtimer_try_to_cancel(timer);
1053
1054        if (ret >= 0)
1055            return ret;
1056        cpu_relax();
1057    }
1058}
1059EXPORT_SYMBOL_GPL(hrtimer_cancel);
1060
1061/**
1062 * hrtimer_get_remaining - get remaining time for the timer
1063 * @timer: the timer to read
1064 */
1065ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
1066{
1067    unsigned long flags;
1068    ktime_t rem;
1069
1070    lock_hrtimer_base(timer, &flags);
1071    rem = hrtimer_expires_remaining(timer);
1072    unlock_hrtimer_base(timer, &flags);
1073
1074    return rem;
1075}
1076EXPORT_SYMBOL_GPL(hrtimer_get_remaining);
1077
1078#ifdef CONFIG_NO_HZ
1079/**
1080 * hrtimer_get_next_event - get the time until next expiry event
1081 *
1082 * Returns the delta to the next expiry event or KTIME_MAX if no timer
1083 * is pending.
1084 */
1085ktime_t hrtimer_get_next_event(void)
1086{
1087    struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1088    struct hrtimer_clock_base *base = cpu_base->clock_base;
1089    ktime_t delta, mindelta = { .tv64 = KTIME_MAX };
1090    unsigned long flags;
1091    int i;
1092
1093    raw_spin_lock_irqsave(&cpu_base->lock, flags);
1094
1095    if (!hrtimer_hres_active()) {
1096        for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++, base++) {
1097            struct hrtimer *timer;
1098            struct timerqueue_node *next;
1099
1100            next = timerqueue_getnext(&base->active);
1101            if (!next)
1102                continue;
1103
1104            timer = container_of(next, struct hrtimer, node);
1105            delta.tv64 = hrtimer_get_expires_tv64(timer);
1106            delta = ktime_sub(delta, base->get_time());
1107            if (delta.tv64 < mindelta.tv64)
1108                mindelta.tv64 = delta.tv64;
1109        }
1110    }
1111
1112    raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1113
1114    if (mindelta.tv64 < 0)
1115        mindelta.tv64 = 0;
1116    return mindelta;
1117}
1118#endif
1119
1120static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1121               enum hrtimer_mode mode)
1122{
1123    struct hrtimer_cpu_base *cpu_base;
1124
1125    memset(timer, 0, sizeof(struct hrtimer));
1126
1127    cpu_base = &__raw_get_cpu_var(hrtimer_bases);
1128
1129    if (clock_id == CLOCK_REALTIME && mode != HRTIMER_MODE_ABS)
1130        clock_id = CLOCK_MONOTONIC;
1131
1132    timer->base = &cpu_base->clock_base[clock_id];
1133    hrtimer_init_timer_hres(timer);
1134    timerqueue_init(&timer->node);
1135
1136#ifdef CONFIG_TIMER_STATS
1137    timer->start_site = NULL;
1138    timer->start_pid = -1;
1139    memset(timer->start_comm, 0, TASK_COMM_LEN);
1140#endif
1141}
1142
1143/**
1144 * hrtimer_init - initialize a timer to the given clock
1145 * @timer: the timer to be initialized
1146 * @clock_id: the clock to be used
1147 * @mode: timer mode abs/rel
1148 */
1149void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1150          enum hrtimer_mode mode)
1151{
1152    debug_init(timer, clock_id, mode);
1153    __hrtimer_init(timer, clock_id, mode);
1154}
1155EXPORT_SYMBOL_GPL(hrtimer_init);
1156
1157/**
1158 * hrtimer_get_res - get the timer resolution for a clock
1159 * @which_clock: which clock to query
1160 * @tp: pointer to timespec variable to store the resolution
1161 *
1162 * Store the resolution of the clock selected by @which_clock in the
1163 * variable pointed to by @tp.
1164 */
1165int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
1166{
1167    struct hrtimer_cpu_base *cpu_base;
1168
1169    cpu_base = &__raw_get_cpu_var(hrtimer_bases);
1170    *tp = ktime_to_timespec(cpu_base->clock_base[which_clock].resolution);
1171
1172    return 0;
1173}
1174EXPORT_SYMBOL_GPL(hrtimer_get_res);
1175
1176static void __run_hrtimer(struct hrtimer *timer, ktime_t *now)
1177{
1178    struct hrtimer_clock_base *base = timer->base;
1179    struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1180    enum hrtimer_restart (*fn)(struct hrtimer *);
1181    int restart;
1182
1183    WARN_ON(!irqs_disabled());
1184
1185    debug_deactivate(timer);
1186    __remove_hrtimer(timer, base, HRTIMER_STATE_CALLBACK, 0);
1187    timer_stats_account_hrtimer(timer);
1188    fn = timer->function;
1189
1190    /*
1191     * Because we run timers from hardirq context, there is no chance
1192     * they get migrated to another cpu, therefore its safe to unlock
1193     * the timer base.
1194     */
1195    raw_spin_unlock(&cpu_base->lock);
1196    trace_hrtimer_expire_entry(timer, now);
1197    restart = fn(timer);
1198    trace_hrtimer_expire_exit(timer);
1199    raw_spin_lock(&cpu_base->lock);
1200
1201    /*
1202     * Note: We clear the CALLBACK bit after enqueue_hrtimer and
1203     * we do not reprogramm the event hardware. Happens either in
1204     * hrtimer_start_range_ns() or in hrtimer_interrupt()
1205     */
1206    if (restart != HRTIMER_NORESTART) {
1207        BUG_ON(timer->state != HRTIMER_STATE_CALLBACK);
1208        enqueue_hrtimer(timer, base);
1209    }
1210
1211    WARN_ON_ONCE(!(timer->state & HRTIMER_STATE_CALLBACK));
1212
1213    timer->state &= ~HRTIMER_STATE_CALLBACK;
1214}
1215
1216#ifdef CONFIG_HIGH_RES_TIMERS
1217
1218/*
1219 * High resolution timer interrupt
1220 * Called with interrupts disabled
1221 */
1222void hrtimer_interrupt(struct clock_event_device *dev)
1223{
1224    struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1225    struct hrtimer_clock_base *base;
1226    ktime_t expires_next, now, entry_time, delta;
1227    int i, retries = 0;
1228
1229    BUG_ON(!cpu_base->hres_active);
1230    cpu_base->nr_events++;
1231    dev->next_event.tv64 = KTIME_MAX;
1232
1233    entry_time = now = ktime_get();
1234retry:
1235    expires_next.tv64 = KTIME_MAX;
1236
1237    raw_spin_lock(&cpu_base->lock);
1238    /*
1239     * We set expires_next to KTIME_MAX here with cpu_base->lock
1240     * held to prevent that a timer is enqueued in our queue via
1241     * the migration code. This does not affect enqueueing of
1242     * timers which run their callback and need to be requeued on
1243     * this CPU.
1244     */
1245    cpu_base->expires_next.tv64 = KTIME_MAX;
1246
1247    base = cpu_base->clock_base;
1248
1249    for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1250        ktime_t basenow;
1251        struct timerqueue_node *node;
1252
1253        basenow = ktime_add(now, base->offset);
1254
1255        while ((node = timerqueue_getnext(&base->active))) {
1256            struct hrtimer *timer;
1257
1258            timer = container_of(node, struct hrtimer, node);
1259
1260            /*
1261             * The immediate goal for using the softexpires is
1262             * minimizing wakeups, not running timers at the
1263             * earliest interrupt after their soft expiration.
1264             * This allows us to avoid using a Priority Search
1265             * Tree, which can answer a stabbing querry for
1266             * overlapping intervals and instead use the simple
1267             * BST we already have.
1268             * We don't add extra wakeups by delaying timers that
1269             * are right-of a not yet expired timer, because that
1270             * timer will have to trigger a wakeup anyway.
1271             */
1272
1273            if (basenow.tv64 < hrtimer_get_softexpires_tv64(timer)) {
1274                ktime_t expires;
1275
1276                expires = ktime_sub(hrtimer_get_expires(timer),
1277                            base->offset);
1278                if (expires.tv64 < expires_next.tv64)
1279                    expires_next = expires;
1280                break;
1281            }
1282
1283            __run_hrtimer(timer, &basenow);
1284        }
1285        base++;
1286    }
1287
1288    /*
1289     * Store the new expiry value so the migration code can verify
1290     * against it.
1291     */
1292    cpu_base->expires_next = expires_next;
1293    raw_spin_unlock(&cpu_base->lock);
1294
1295    /* Reprogramming necessary ? */
1296    if (expires_next.tv64 == KTIME_MAX ||
1297        !tick_program_event(expires_next, 0)) {
1298        cpu_base->hang_detected = 0;
1299        return;
1300    }
1301
1302    /*
1303     * The next timer was already expired due to:
1304     * - tracing
1305     * - long lasting callbacks
1306     * - being scheduled away when running in a VM
1307     *
1308     * We need to prevent that we loop forever in the hrtimer
1309     * interrupt routine. We give it 3 attempts to avoid
1310     * overreacting on some spurious event.
1311     */
1312    now = ktime_get();
1313    cpu_base->nr_retries++;
1314    if (++retries < 3)
1315        goto retry;
1316    /*
1317     * Give the system a chance to do something else than looping
1318     * here. We stored the entry time, so we know exactly how long
1319     * we spent here. We schedule the next event this amount of
1320     * time away.
1321     */
1322    cpu_base->nr_hangs++;
1323    cpu_base->hang_detected = 1;
1324    delta = ktime_sub(now, entry_time);
1325    if (delta.tv64 > cpu_base->max_hang_time.tv64)
1326        cpu_base->max_hang_time = delta;
1327    /*
1328     * Limit it to a sensible value as we enforce a longer
1329     * delay. Give the CPU at least 100ms to catch up.
1330     */
1331    if (delta.tv64 > 100 * NSEC_PER_MSEC)
1332        expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1333    else
1334        expires_next = ktime_add(now, delta);
1335    tick_program_event(expires_next, 1);
1336    printk_once(KERN_WARNING "hrtimer: interrupt took %llu ns\n",
1337            ktime_to_ns(delta));
1338}
1339
1340/*
1341 * local version of hrtimer_peek_ahead_timers() called with interrupts
1342 * disabled.
1343 */
1344static void __hrtimer_peek_ahead_timers(void)
1345{
1346    struct tick_device *td;
1347
1348    if (!hrtimer_hres_active())
1349        return;
1350
1351    td = &__get_cpu_var(tick_cpu_device);
1352    if (td && td->evtdev)
1353        hrtimer_interrupt(td->evtdev);
1354}
1355
1356/**
1357 * hrtimer_peek_ahead_timers -- run soft-expired timers now
1358 *
1359 * hrtimer_peek_ahead_timers will peek at the timer queue of
1360 * the current cpu and check if there are any timers for which
1361 * the soft expires time has passed. If any such timers exist,
1362 * they are run immediately and then removed from the timer queue.
1363 *
1364 */
1365void hrtimer_peek_ahead_timers(void)
1366{
1367    unsigned long flags;
1368
1369    local_irq_save(flags);
1370    __hrtimer_peek_ahead_timers();
1371    local_irq_restore(flags);
1372}
1373
1374static void run_hrtimer_softirq(struct softirq_action *h)
1375{
1376    hrtimer_peek_ahead_timers();
1377}
1378
1379#else /* CONFIG_HIGH_RES_TIMERS */
1380
1381static inline void __hrtimer_peek_ahead_timers(void) { }
1382
1383#endif /* !CONFIG_HIGH_RES_TIMERS */
1384
1385/*
1386 * Called from timer softirq every jiffy, expire hrtimers:
1387 *
1388 * For HRT its the fall back code to run the softirq in the timer
1389 * softirq context in case the hrtimer initialization failed or has
1390 * not been done yet.
1391 */
1392void hrtimer_run_pending(void)
1393{
1394    if (hrtimer_hres_active())
1395        return;
1396
1397    /*
1398     * This _is_ ugly: We have to check in the softirq context,
1399     * whether we can switch to highres and / or nohz mode. The
1400     * clocksource switch happens in the timer interrupt with
1401     * xtime_lock held. Notification from there only sets the
1402     * check bit in the tick_oneshot code, otherwise we might
1403     * deadlock vs. xtime_lock.
1404     */
1405    if (tick_check_oneshot_change(!hrtimer_is_hres_enabled()))
1406        hrtimer_switch_to_hres();
1407}
1408
1409/*
1410 * Called from hardirq context every jiffy
1411 */
1412void hrtimer_run_queues(void)
1413{
1414    struct timerqueue_node *node;
1415    struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
1416    struct hrtimer_clock_base *base;
1417    int index, gettime = 1;
1418
1419    if (hrtimer_hres_active())
1420        return;
1421
1422    for (index = 0; index < HRTIMER_MAX_CLOCK_BASES; index++) {
1423        base = &cpu_base->clock_base[index];
1424        if (!timerqueue_getnext(&base->active))
1425            continue;
1426
1427        if (gettime) {
1428            hrtimer_get_softirq_time(cpu_base);
1429            gettime = 0;
1430        }
1431
1432        raw_spin_lock(&cpu_base->lock);
1433
1434        while ((node = timerqueue_getnext(&base->active))) {
1435            struct hrtimer *timer;
1436
1437            timer = container_of(node, struct hrtimer, node);
1438            if (base->softirq_time.tv64 <=
1439                    hrtimer_get_expires_tv64(timer))
1440                break;
1441
1442            __run_hrtimer(timer, &base->softirq_time);
1443        }
1444        raw_spin_unlock(&cpu_base->lock);
1445    }
1446}
1447
1448/*
1449 * Sleep related functions:
1450 */
1451static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1452{
1453    struct hrtimer_sleeper *t =
1454        container_of(timer, struct hrtimer_sleeper, timer);
1455    struct task_struct *task = t->task;
1456
1457    t->task = NULL;
1458    if (task)
1459        wake_up_process(task);
1460
1461    return HRTIMER_NORESTART;
1462}
1463
1464void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task)
1465{
1466    sl->timer.function = hrtimer_wakeup;
1467    sl->task = task;
1468}
1469EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
1470
1471static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
1472{
1473    hrtimer_init_sleeper(t, current);
1474
1475    do {
1476        set_current_state(TASK_INTERRUPTIBLE);
1477        hrtimer_start_expires(&t->timer, mode);
1478        if (!hrtimer_active(&t->timer))
1479            t->task = NULL;
1480
1481        if (likely(t->task))
1482            schedule();
1483
1484        hrtimer_cancel(&t->timer);
1485        mode = HRTIMER_MODE_ABS;
1486
1487    } while (t->task && !signal_pending(current));
1488
1489    __set_current_state(TASK_RUNNING);
1490
1491    return t->task == NULL;
1492}
1493
1494static int update_rmtp(struct hrtimer *timer, struct timespec __user *rmtp)
1495{
1496    struct timespec rmt;
1497    ktime_t rem;
1498
1499    rem = hrtimer_expires_remaining(timer);
1500    if (rem.tv64 <= 0)
1501        return 0;
1502    rmt = ktime_to_timespec(rem);
1503
1504    if (copy_to_user(rmtp, &rmt, sizeof(*rmtp)))
1505        return -EFAULT;
1506
1507    return 1;
1508}
1509
1510long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
1511{
1512    struct hrtimer_sleeper t;
1513    struct timespec __user *rmtp;
1514    int ret = 0;
1515
1516    hrtimer_init_on_stack(&t.timer, restart->nanosleep.index,
1517                HRTIMER_MODE_ABS);
1518    hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
1519
1520    if (do_nanosleep(&t, HRTIMER_MODE_ABS))
1521        goto out;
1522
1523    rmtp = restart->nanosleep.rmtp;
1524    if (rmtp) {
1525        ret = update_rmtp(&t.timer, rmtp);
1526        if (ret <= 0)
1527            goto out;
1528    }
1529
1530    /* The other values in restart are already filled in */
1531    ret = -ERESTART_RESTARTBLOCK;
1532out:
1533    destroy_hrtimer_on_stack(&t.timer);
1534    return ret;
1535}
1536
1537long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
1538               const enum hrtimer_mode mode, const clockid_t clockid)
1539{
1540    struct restart_block *restart;
1541    struct hrtimer_sleeper t;
1542    int ret = 0;
1543    unsigned long slack;
1544
1545    slack = current->timer_slack_ns;
1546    if (rt_task(current))
1547        slack = 0;
1548
1549    hrtimer_init_on_stack(&t.timer, clockid, mode);
1550    hrtimer_set_expires_range_ns(&t.timer, timespec_to_ktime(*rqtp), slack);
1551    if (do_nanosleep(&t, mode))
1552        goto out;
1553
1554    /* Absolute timers do not update the rmtp value and restart: */
1555    if (mode == HRTIMER_MODE_ABS) {
1556        ret = -ERESTARTNOHAND;
1557        goto out;
1558    }
1559
1560    if (rmtp) {
1561        ret = update_rmtp(&t.timer, rmtp);
1562        if (ret <= 0)
1563            goto out;
1564    }
1565
1566    restart = &current_thread_info()->restart_block;
1567    restart->fn = hrtimer_nanosleep_restart;
1568    restart->nanosleep.index = t.timer.base->index;
1569    restart->nanosleep.rmtp = rmtp;
1570    restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
1571
1572    ret = -ERESTART_RESTARTBLOCK;
1573out:
1574    destroy_hrtimer_on_stack(&t.timer);
1575    return ret;
1576}
1577
1578SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
1579        struct timespec __user *, rmtp)
1580{
1581    struct timespec tu;
1582
1583    if (copy_from_user(&tu, rqtp, sizeof(tu)))
1584        return -EFAULT;
1585
1586    if (!timespec_valid(&tu))
1587        return -EINVAL;
1588
1589    return hrtimer_nanosleep(&tu, rmtp, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
1590}
1591
1592/*
1593 * Functions related to boot-time initialization:
1594 */
1595static void __cpuinit init_hrtimers_cpu(int cpu)
1596{
1597    struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
1598    int i;
1599
1600    raw_spin_lock_init(&cpu_base->lock);
1601
1602    for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1603        cpu_base->clock_base[i].cpu_base = cpu_base;
1604        timerqueue_init_head(&cpu_base->clock_base[i].active);
1605    }
1606
1607    hrtimer_init_hres(cpu_base);
1608}
1609
1610#ifdef CONFIG_HOTPLUG_CPU
1611
1612static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
1613                struct hrtimer_clock_base *new_base)
1614{
1615    struct hrtimer *timer;
1616    struct timerqueue_node *node;
1617
1618    while ((node = timerqueue_getnext(&old_base->active))) {
1619        timer = container_of(node, struct hrtimer, node);
1620        BUG_ON(hrtimer_callback_running(timer));
1621        debug_deactivate(timer);
1622
1623        /*
1624         * Mark it as STATE_MIGRATE not INACTIVE otherwise the
1625         * timer could be seen as !active and just vanish away
1626         * under us on another CPU
1627         */
1628        __remove_hrtimer(timer, old_base, HRTIMER_STATE_MIGRATE, 0);
1629        timer->base = new_base;
1630        /*
1631         * Enqueue the timers on the new cpu. This does not
1632         * reprogram the event device in case the timer
1633         * expires before the earliest on this CPU, but we run
1634         * hrtimer_interrupt after we migrated everything to
1635         * sort out already expired timers and reprogram the
1636         * event device.
1637         */
1638        enqueue_hrtimer(timer, new_base);
1639
1640        /* Clear the migration state bit */
1641        timer->state &= ~HRTIMER_STATE_MIGRATE;
1642    }
1643}
1644
1645static void migrate_hrtimers(int scpu)
1646{
1647    struct hrtimer_cpu_base *old_base, *new_base;
1648    int i;
1649
1650    BUG_ON(cpu_online(scpu));
1651    tick_cancel_sched_timer(scpu);
1652
1653    local_irq_disable();
1654    old_base = &per_cpu(hrtimer_bases, scpu);
1655    new_base = &__get_cpu_var(hrtimer_bases);
1656    /*
1657     * The caller is globally serialized and nobody else
1658     * takes two locks at once, deadlock is not possible.
1659     */
1660    raw_spin_lock(&new_base->lock);
1661    raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1662
1663    for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1664        migrate_hrtimer_list(&old_base->clock_base[i],
1665                     &new_base->clock_base[i]);
1666    }
1667
1668    raw_spin_unlock(&old_base->lock);
1669    raw_spin_unlock(&new_base->lock);
1670
1671    /* Check, if we got expired work to do */
1672    __hrtimer_peek_ahead_timers();
1673    local_irq_enable();
1674}
1675
1676#endif /* CONFIG_HOTPLUG_CPU */
1677
1678static int __cpuinit hrtimer_cpu_notify(struct notifier_block *self,
1679                    unsigned long action, void *hcpu)
1680{
1681    int scpu = (long)hcpu;
1682
1683    switch (action) {
1684
1685    case CPU_UP_PREPARE:
1686    case CPU_UP_PREPARE_FROZEN:
1687        init_hrtimers_cpu(scpu);
1688        break;
1689
1690#ifdef CONFIG_HOTPLUG_CPU
1691    case CPU_DYING:
1692    case CPU_DYING_FROZEN:
1693        clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DYING, &scpu);
1694        break;
1695    case CPU_DEAD:
1696    case CPU_DEAD_FROZEN:
1697    {
1698        clockevents_notify(CLOCK_EVT_NOTIFY_CPU_DEAD, &scpu);
1699        migrate_hrtimers(scpu);
1700        break;
1701    }
1702#endif
1703
1704    default:
1705        break;
1706    }
1707
1708    return NOTIFY_OK;
1709}
1710
1711static struct notifier_block __cpuinitdata hrtimers_nb = {
1712    .notifier_call = hrtimer_cpu_notify,
1713};
1714
1715void __init hrtimers_init(void)
1716{
1717    hrtimer_cpu_notify(&hrtimers_nb, (unsigned long)CPU_UP_PREPARE,
1718              (void *)(long)smp_processor_id());
1719    register_cpu_notifier(&hrtimers_nb);
1720#ifdef CONFIG_HIGH_RES_TIMERS
1721    open_softirq(HRTIMER_SOFTIRQ, run_hrtimer_softirq);
1722#endif
1723}
1724
1725/**
1726 * schedule_hrtimeout_range_clock - sleep until timeout
1727 * @expires: timeout value (ktime_t)
1728 * @delta: slack in expires timeout (ktime_t)
1729 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1730 * @clock: timer clock, CLOCK_MONOTONIC or CLOCK_REALTIME
1731 */
1732int __sched
1733schedule_hrtimeout_range_clock(ktime_t *expires, unsigned long delta,
1734                   const enum hrtimer_mode mode, int clock)
1735{
1736    struct hrtimer_sleeper t;
1737
1738    /*
1739     * Optimize when a zero timeout value is given. It does not
1740     * matter whether this is an absolute or a relative time.
1741     */
1742    if (expires && !expires->tv64) {
1743        __set_current_state(TASK_RUNNING);
1744        return 0;
1745    }
1746
1747    /*
1748     * A NULL parameter means "infinite"
1749     */
1750    if (!expires) {
1751        schedule();
1752        __set_current_state(TASK_RUNNING);
1753        return -EINTR;
1754    }
1755
1756    hrtimer_init_on_stack(&t.timer, clock, mode);
1757    hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
1758
1759    hrtimer_init_sleeper(&t, current);
1760
1761    hrtimer_start_expires(&t.timer, mode);
1762    if (!hrtimer_active(&t.timer))
1763        t.task = NULL;
1764
1765    if (likely(t.task))
1766        schedule();
1767
1768    hrtimer_cancel(&t.timer);
1769    destroy_hrtimer_on_stack(&t.timer);
1770
1771    __set_current_state(TASK_RUNNING);
1772
1773    return !t.task ? 0 : -EINTR;
1774}
1775
1776/**
1777 * schedule_hrtimeout_range - sleep until timeout
1778 * @expires: timeout value (ktime_t)
1779 * @delta: slack in expires timeout (ktime_t)
1780 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1781 *
1782 * Make the current task sleep until the given expiry time has
1783 * elapsed. The routine will return immediately unless
1784 * the current task state has been set (see set_current_state()).
1785 *
1786 * The @delta argument gives the kernel the freedom to schedule the
1787 * actual wakeup to a time that is both power and performance friendly.
1788 * The kernel give the normal best effort behavior for "@expires+@delta",
1789 * but may decide to fire the timer earlier, but no earlier than @expires.
1790 *
1791 * You can set the task state as follows -
1792 *
1793 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1794 * pass before the routine returns.
1795 *
1796 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1797 * delivered to the current task.
1798 *
1799 * The current task state is guaranteed to be TASK_RUNNING when this
1800 * routine returns.
1801 *
1802 * Returns 0 when the timer has expired otherwise -EINTR
1803 */
1804int __sched schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
1805                     const enum hrtimer_mode mode)
1806{
1807    return schedule_hrtimeout_range_clock(expires, delta, mode,
1808                          CLOCK_MONOTONIC);
1809}
1810EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
1811
1812/**
1813 * schedule_hrtimeout - sleep until timeout
1814 * @expires: timeout value (ktime_t)
1815 * @mode: timer mode, HRTIMER_MODE_ABS or HRTIMER_MODE_REL
1816 *
1817 * Make the current task sleep until the given expiry time has
1818 * elapsed. The routine will return immediately unless
1819 * the current task state has been set (see set_current_state()).
1820 *
1821 * You can set the task state as follows -
1822 *
1823 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1824 * pass before the routine returns.
1825 *
1826 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1827 * delivered to the current task.
1828 *
1829 * The current task state is guaranteed to be TASK_RUNNING when this
1830 * routine returns.
1831 *
1832 * Returns 0 when the timer has expired otherwise -EINTR
1833 */
1834int __sched schedule_hrtimeout(ktime_t *expires,
1835                   const enum hrtimer_mode mode)
1836{
1837    return schedule_hrtimeout_range(expires, 0, mode);
1838}
1839EXPORT_SYMBOL_GPL(schedule_hrtimeout);
1840

Archive Download this file

Branches:
ben-wpan
ben-wpan-stefan
javiroman/ks7010
jz-2.6.34
jz-2.6.34-rc5
jz-2.6.34-rc6
jz-2.6.34-rc7
jz-2.6.35
jz-2.6.36
jz-2.6.37
jz-2.6.38
jz-2.6.39
jz-3.0
jz-3.1
jz-3.11
jz-3.12
jz-3.13
jz-3.15
jz-3.16
jz-3.18-dt
jz-3.2
jz-3.3
jz-3.4
jz-3.5
jz-3.6
jz-3.6-rc2-pwm
jz-3.9
jz-3.9-clk
jz-3.9-rc8
jz47xx
jz47xx-2.6.38
master

Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
v2.6.34-rc6
v2.6.34-rc7
v3.9



interactive