projects/linux·blob v5.13-rc7 · refs

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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright(C) 2005-2006, Thomas Gleixner <[email protected]>
4 * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
5 * Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner
6 *
7 * High-resolution kernel timers
8 *
9 * In contrast to the low-resolution timeout API, aka timer wheel,
10 * hrtimers provide finer resolution and accuracy depending on system
11 * configuration and capabilities.
12 *
13 * Started by: Thomas Gleixner and Ingo Molnar
14 *
15 * Credits:
16 * Based on the original timer wheel code
17 *
18 * Help, testing, suggestions, bugfixes, improvements were
19 * provided by:
20 *
21 * George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
22 * et. al.
23 */
24
25#include <linux/cpu.h>
26#include <linux/export.h>
27#include <linux/percpu.h>
28#include <linux/hrtimer.h>
29#include <linux/notifier.h>
30#include <linux/syscalls.h>
31#include <linux/interrupt.h>
32#include <linux/tick.h>
33#include <linux/err.h>
34#include <linux/debugobjects.h>
35#include <linux/sched/signal.h>
36#include <linux/sched/sysctl.h>
37#include <linux/sched/rt.h>
38#include <linux/sched/deadline.h>
39#include <linux/sched/nohz.h>
40#include <linux/sched/debug.h>
41#include <linux/timer.h>
42#include <linux/freezer.h>
43#include <linux/compat.h>
44
45#include <linux/uaccess.h>
46
47#include <trace/events/timer.h>
48
49#include "tick-internal.h"
50
51/*
52 * Masks for selecting the soft and hard context timers from
53 * cpu_base->active
54 */
55#define MASK_SHIFT (HRTIMER_BASE_MONOTONIC_SOFT)
56#define HRTIMER_ACTIVE_HARD ((1U << MASK_SHIFT) - 1)
57#define HRTIMER_ACTIVE_SOFT (HRTIMER_ACTIVE_HARD << MASK_SHIFT)
58#define HRTIMER_ACTIVE_ALL (HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD)
59
60/*
61 * The timer bases:
62 *
63 * There are more clockids than hrtimer bases. Thus, we index
64 * into the timer bases by the hrtimer_base_type enum. When trying
65 * to reach a base using a clockid, hrtimer_clockid_to_base()
66 * is used to convert from clockid to the proper hrtimer_base_type.
67 */
68DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
69{
70 .lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
71 .clock_base =
72 {
73 {
74 .index = HRTIMER_BASE_MONOTONIC,
75 .clockid = CLOCK_MONOTONIC,
76 .get_time = &ktime_get,
77 },
78 {
79 .index = HRTIMER_BASE_REALTIME,
80 .clockid = CLOCK_REALTIME,
81 .get_time = &ktime_get_real,
82 },
83 {
84 .index = HRTIMER_BASE_BOOTTIME,
85 .clockid = CLOCK_BOOTTIME,
86 .get_time = &ktime_get_boottime,
87 },
88 {
89 .index = HRTIMER_BASE_TAI,
90 .clockid = CLOCK_TAI,
91 .get_time = &ktime_get_clocktai,
92 },
93 {
94 .index = HRTIMER_BASE_MONOTONIC_SOFT,
95 .clockid = CLOCK_MONOTONIC,
96 .get_time = &ktime_get,
97 },
98 {
99 .index = HRTIMER_BASE_REALTIME_SOFT,
100 .clockid = CLOCK_REALTIME,
101 .get_time = &ktime_get_real,
102 },
103 {
104 .index = HRTIMER_BASE_BOOTTIME_SOFT,
105 .clockid = CLOCK_BOOTTIME,
106 .get_time = &ktime_get_boottime,
107 },
108 {
109 .index = HRTIMER_BASE_TAI_SOFT,
110 .clockid = CLOCK_TAI,
111 .get_time = &ktime_get_clocktai,
112 },
113 }
114};
115
116static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
117 /* Make sure we catch unsupported clockids */
118 [0 ... MAX_CLOCKS - 1] = HRTIMER_MAX_CLOCK_BASES,
119
120 [CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
121 [CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
122 [CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
123 [CLOCK_TAI] = HRTIMER_BASE_TAI,
124};
125
126/*
127 * Functions and macros which are different for UP/SMP systems are kept in a
128 * single place
129 */
130#ifdef CONFIG_SMP
131
132/*
133 * We require the migration_base for lock_hrtimer_base()/switch_hrtimer_base()
134 * such that hrtimer_callback_running() can unconditionally dereference
135 * timer->base->cpu_base
136 */
137static struct hrtimer_cpu_base migration_cpu_base = {
138 .clock_base = { {
139 .cpu_base = &migration_cpu_base,
140 .seq = SEQCNT_RAW_SPINLOCK_ZERO(migration_cpu_base.seq,
141 &migration_cpu_base.lock),
142 }, },
143};
144
145#define migration_base migration_cpu_base.clock_base[0]
146
147static inline bool is_migration_base(struct hrtimer_clock_base *base)
148{
149 return base == &migration_base;
150}
151
152/*
153 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
154 * means that all timers which are tied to this base via timer->base are
155 * locked, and the base itself is locked too.
156 *
157 * So __run_timers/migrate_timers can safely modify all timers which could
158 * be found on the lists/queues.
159 *
160 * When the timer's base is locked, and the timer removed from list, it is
161 * possible to set timer->base = &migration_base and drop the lock: the timer
162 * remains locked.
163 */
164static
165struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
166 unsigned long *flags)
167{
168 struct hrtimer_clock_base *base;
169
170 for (;;) {
171 base = READ_ONCE(timer->base);
172 if (likely(base != &migration_base)) {
173 raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
174 if (likely(base == timer->base))
175 return base;
176 /* The timer has migrated to another CPU: */
177 raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
178 }
179 cpu_relax();
180 }
181}
182
183/*
184 * We do not migrate the timer when it is expiring before the next
185 * event on the target cpu. When high resolution is enabled, we cannot
186 * reprogram the target cpu hardware and we would cause it to fire
187 * late. To keep it simple, we handle the high resolution enabled and
188 * disabled case similar.
189 *
190 * Called with cpu_base->lock of target cpu held.
191 */
192static int
193hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
194{
195 ktime_t expires;
196
197 expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
198 return expires < new_base->cpu_base->expires_next;
199}
200
201static inline
202struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
203 int pinned)
204{
205#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
206 if (static_branch_likely(&timers_migration_enabled) && !pinned)
207 return &per_cpu(hrtimer_bases, get_nohz_timer_target());
208#endif
209 return base;
210}
211
212/*
213 * We switch the timer base to a power-optimized selected CPU target,
214 * if:
215 * - NO_HZ_COMMON is enabled
216 * - timer migration is enabled
217 * - the timer callback is not running
218 * - the timer is not the first expiring timer on the new target
219 *
220 * If one of the above requirements is not fulfilled we move the timer
221 * to the current CPU or leave it on the previously assigned CPU if
222 * the timer callback is currently running.
223 */
224static inline struct hrtimer_clock_base *
225switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
226 int pinned)
227{
228 struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
229 struct hrtimer_clock_base *new_base;
230 int basenum = base->index;
231
232 this_cpu_base = this_cpu_ptr(&hrtimer_bases);
233 new_cpu_base = get_target_base(this_cpu_base, pinned);
234again:
235 new_base = &new_cpu_base->clock_base[basenum];
236
237 if (base != new_base) {
238 /*
239 * We are trying to move timer to new_base.
240 * However we can't change timer's base while it is running,
241 * so we keep it on the same CPU. No hassle vs. reprogramming
242 * the event source in the high resolution case. The softirq
243 * code will take care of this when the timer function has
244 * completed. There is no conflict as we hold the lock until
245 * the timer is enqueued.
246 */
247 if (unlikely(hrtimer_callback_running(timer)))
248 return base;
249
250 /* See the comment in lock_hrtimer_base() */
251 WRITE_ONCE(timer->base, &migration_base);
252 raw_spin_unlock(&base->cpu_base->lock);
253 raw_spin_lock(&new_base->cpu_base->lock);
254
255 if (new_cpu_base != this_cpu_base &&
256 hrtimer_check_target(timer, new_base)) {
257 raw_spin_unlock(&new_base->cpu_base->lock);
258 raw_spin_lock(&base->cpu_base->lock);
259 new_cpu_base = this_cpu_base;
260 WRITE_ONCE(timer->base, base);
261 goto again;
262 }
263 WRITE_ONCE(timer->base, new_base);
264 } else {
265 if (new_cpu_base != this_cpu_base &&
266 hrtimer_check_target(timer, new_base)) {
267 new_cpu_base = this_cpu_base;
268 goto again;
269 }
270 }
271 return new_base;
272}
273
274#else /* CONFIG_SMP */
275
276static inline bool is_migration_base(struct hrtimer_clock_base *base)
277{
278 return false;
279}
280
281static inline struct hrtimer_clock_base *
282lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
283{
284 struct hrtimer_clock_base *base = timer->base;
285
286 raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
287
288 return base;
289}
290
291# define switch_hrtimer_base(t, b, p) (b)
292
293#endif /* !CONFIG_SMP */
294
295/*
296 * Functions for the union type storage format of ktime_t which are
297 * too large for inlining:
298 */
299#if BITS_PER_LONG < 64
300/*
301 * Divide a ktime value by a nanosecond value
302 */
303s64 __ktime_divns(const ktime_t kt, s64 div)
304{
305 int sft = 0;
306 s64 dclc;
307 u64 tmp;
308
309 dclc = ktime_to_ns(kt);
310 tmp = dclc < 0 ? -dclc : dclc;
311
312 /* Make sure the divisor is less than 2^32: */
313 while (div >> 32) {
314 sft++;
315 div >>= 1;
316 }
317 tmp >>= sft;
318 do_div(tmp, (u32) div);
319 return dclc < 0 ? -tmp : tmp;
320}
321EXPORT_SYMBOL_GPL(__ktime_divns);
322#endif /* BITS_PER_LONG >= 64 */
323
324/*
325 * Add two ktime values and do a safety check for overflow:
326 */
327ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
328{
329 ktime_t res = ktime_add_unsafe(lhs, rhs);
330
331 /*
332 * We use KTIME_SEC_MAX here, the maximum timeout which we can
333 * return to user space in a timespec:
334 */
335 if (res < 0 || res < lhs || res < rhs)
336 res = ktime_set(KTIME_SEC_MAX, 0);
337
338 return res;
339}
340
341EXPORT_SYMBOL_GPL(ktime_add_safe);
342
343#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
344
345static const struct debug_obj_descr hrtimer_debug_descr;
346
347static void *hrtimer_debug_hint(void *addr)
348{
349 return ((struct hrtimer *) addr)->function;
350}
351
352/*
353 * fixup_init is called when:
354 * - an active object is initialized
355 */
356static bool hrtimer_fixup_init(void *addr, enum debug_obj_state state)
357{
358 struct hrtimer *timer = addr;
359
360 switch (state) {
361 case ODEBUG_STATE_ACTIVE:
362 hrtimer_cancel(timer);
363 debug_object_init(timer, &hrtimer_debug_descr);
364 return true;
365 default:
366 return false;
367 }
368}
369
370/*
371 * fixup_activate is called when:
372 * - an active object is activated
373 * - an unknown non-static object is activated
374 */
375static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
376{
377 switch (state) {
378 case ODEBUG_STATE_ACTIVE:
379 WARN_ON(1);
380 fallthrough;
381 default:
382 return false;
383 }
384}
385
386/*
387 * fixup_free is called when:
388 * - an active object is freed
389 */
390static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state)
391{
392 struct hrtimer *timer = addr;
393
394 switch (state) {
395 case ODEBUG_STATE_ACTIVE:
396 hrtimer_cancel(timer);
397 debug_object_free(timer, &hrtimer_debug_descr);
398 return true;
399 default:
400 return false;
401 }
402}
403
404static const struct debug_obj_descr hrtimer_debug_descr = {
405 .name = "hrtimer",
406 .debug_hint = hrtimer_debug_hint,
407 .fixup_init = hrtimer_fixup_init,
408 .fixup_activate = hrtimer_fixup_activate,
409 .fixup_free = hrtimer_fixup_free,
410};
411
412static inline void debug_hrtimer_init(struct hrtimer *timer)
413{
414 debug_object_init(timer, &hrtimer_debug_descr);
415}
416
417static inline void debug_hrtimer_activate(struct hrtimer *timer,
418 enum hrtimer_mode mode)
419{
420 debug_object_activate(timer, &hrtimer_debug_descr);
421}
422
423static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
424{
425 debug_object_deactivate(timer, &hrtimer_debug_descr);
426}
427
428static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
429 enum hrtimer_mode mode);
430
431void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
432 enum hrtimer_mode mode)
433{
434 debug_object_init_on_stack(timer, &hrtimer_debug_descr);
435 __hrtimer_init(timer, clock_id, mode);
436}
437EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
438
439static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
440 clockid_t clock_id, enum hrtimer_mode mode);
441
442void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
443 clockid_t clock_id, enum hrtimer_mode mode)
444{
445 debug_object_init_on_stack(&sl->timer, &hrtimer_debug_descr);
446 __hrtimer_init_sleeper(sl, clock_id, mode);
447}
448EXPORT_SYMBOL_GPL(hrtimer_init_sleeper_on_stack);
449
450void destroy_hrtimer_on_stack(struct hrtimer *timer)
451{
452 debug_object_free(timer, &hrtimer_debug_descr);
453}
454EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
455
456#else
457
458static inline void debug_hrtimer_init(struct hrtimer *timer) { }
459static inline void debug_hrtimer_activate(struct hrtimer *timer,
460 enum hrtimer_mode mode) { }
461static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
462#endif
463
464static inline void
465debug_init(struct hrtimer *timer, clockid_t clockid,
466 enum hrtimer_mode mode)
467{
468 debug_hrtimer_init(timer);
469 trace_hrtimer_init(timer, clockid, mode);
470}
471
472static inline void debug_activate(struct hrtimer *timer,
473 enum hrtimer_mode mode)
474{
475 debug_hrtimer_activate(timer, mode);
476 trace_hrtimer_start(timer, mode);
477}
478
479static inline void debug_deactivate(struct hrtimer *timer)
480{
481 debug_hrtimer_deactivate(timer);
482 trace_hrtimer_cancel(timer);
483}
484
485static struct hrtimer_clock_base *
486__next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
487{
488 unsigned int idx;
489
490 if (!*active)
491 return NULL;
492
493 idx = __ffs(*active);
494 *active &= ~(1U << idx);
495
496 return &cpu_base->clock_base[idx];
497}
498
499#define for_each_active_base(base, cpu_base, active) \
500 while ((base = __next_base((cpu_base), &(active))))
501
502static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
503 const struct hrtimer *exclude,
504 unsigned int active,
505 ktime_t expires_next)
506{
507 struct hrtimer_clock_base *base;
508 ktime_t expires;
509
510 for_each_active_base(base, cpu_base, active) {
511 struct timerqueue_node *next;
512 struct hrtimer *timer;
513
514 next = timerqueue_getnext(&base->active);
515 timer = container_of(next, struct hrtimer, node);
516 if (timer == exclude) {
517 /* Get to the next timer in the queue. */
518 next = timerqueue_iterate_next(next);
519 if (!next)
520 continue;
521
522 timer = container_of(next, struct hrtimer, node);
523 }
524 expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
525 if (expires < expires_next) {
526 expires_next = expires;
527
528 /* Skip cpu_base update if a timer is being excluded. */
529 if (exclude)
530 continue;
531
532 if (timer->is_soft)
533 cpu_base->softirq_next_timer = timer;
534 else
535 cpu_base->next_timer = timer;
536 }
537 }
538 /*
539 * clock_was_set() might have changed base->offset of any of
540 * the clock bases so the result might be negative. Fix it up
541 * to prevent a false positive in clockevents_program_event().
542 */
543 if (expires_next < 0)
544 expires_next = 0;
545 return expires_next;
546}
547
548/*
549 * Recomputes cpu_base::*next_timer and returns the earliest expires_next
550 * but does not set cpu_base::*expires_next, that is done by
551 * hrtimer[_force]_reprogram and hrtimer_interrupt only. When updating
552 * cpu_base::*expires_next right away, reprogramming logic would no longer
553 * work.
554 *
555 * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
556 * those timers will get run whenever the softirq gets handled, at the end of
557 * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
558 *
559 * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
560 * The !softirq values are the minima across HRTIMER_ACTIVE_ALL, unless an actual
561 * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
562 *
563 * @active_mask must be one of:
564 * - HRTIMER_ACTIVE_ALL,
565 * - HRTIMER_ACTIVE_SOFT, or
566 * - HRTIMER_ACTIVE_HARD.
567 */
568static ktime_t
569__hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
570{
571 unsigned int active;
572 struct hrtimer *next_timer = NULL;
573 ktime_t expires_next = KTIME_MAX;
574
575 if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
576 active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
577 cpu_base->softirq_next_timer = NULL;
578 expires_next = __hrtimer_next_event_base(cpu_base, NULL,
579 active, KTIME_MAX);
580
581 next_timer = cpu_base->softirq_next_timer;
582 }
583
584 if (active_mask & HRTIMER_ACTIVE_HARD) {
585 active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
586 cpu_base->next_timer = next_timer;
587 expires_next = __hrtimer_next_event_base(cpu_base, NULL, active,
588 expires_next);
589 }
590
591 return expires_next;
592}
593
594static ktime_t hrtimer_update_next_event(struct hrtimer_cpu_base *cpu_base)
595{
596 ktime_t expires_next, soft = KTIME_MAX;
597
598 /*
599 * If the soft interrupt has already been activated, ignore the
600 * soft bases. They will be handled in the already raised soft
601 * interrupt.
602 */
603 if (!cpu_base->softirq_activated) {
604 soft = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
605 /*
606 * Update the soft expiry time. clock_settime() might have
607 * affected it.
608 */
609 cpu_base->softirq_expires_next = soft;
610 }
611
612 expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
613 /*
614 * If a softirq timer is expiring first, update cpu_base->next_timer
615 * and program the hardware with the soft expiry time.
616 */
617 if (expires_next > soft) {
618 cpu_base->next_timer = cpu_base->softirq_next_timer;
619 expires_next = soft;
620 }
621
622 return expires_next;
623}
624
625static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
626{
627 ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
628 ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
629 ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
630
631 ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
632 offs_real, offs_boot, offs_tai);
633
634 base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
635 base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
636 base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
637
638 return now;
639}
640
641/*
642 * Is the high resolution mode active ?
643 */
644static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
645{
646 return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
647 cpu_base->hres_active : 0;
648}
649
650static inline int hrtimer_hres_active(void)
651{
652 return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
653}
654
655/*
656 * Reprogram the event source with checking both queues for the
657 * next event
658 * Called with interrupts disabled and base->lock held
659 */
660static void
661hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
662{
663 ktime_t expires_next;
664
665 expires_next = hrtimer_update_next_event(cpu_base);
666
667 if (skip_equal && expires_next == cpu_base->expires_next)
668 return;
669
670 cpu_base->expires_next = expires_next;
671
672 /*
673 * If hres is not active, hardware does not have to be
674 * reprogrammed yet.
675 *
676 * If a hang was detected in the last timer interrupt then we
677 * leave the hang delay active in the hardware. We want the
678 * system to make progress. That also prevents the following
679 * scenario:
680 * T1 expires 50ms from now
681 * T2 expires 5s from now
682 *
683 * T1 is removed, so this code is called and would reprogram
684 * the hardware to 5s from now. Any hrtimer_start after that
685 * will not reprogram the hardware due to hang_detected being
686 * set. So we'd effectively block all timers until the T2 event
687 * fires.
688 */
689 if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
690 return;
691
692 tick_program_event(cpu_base->expires_next, 1);
693}
694
695/* High resolution timer related functions */
696#ifdef CONFIG_HIGH_RES_TIMERS
697
698/*
699 * High resolution timer enabled ?
700 */
701static bool hrtimer_hres_enabled __read_mostly = true;
702unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
703EXPORT_SYMBOL_GPL(hrtimer_resolution);
704
705/*
706 * Enable / Disable high resolution mode
707 */
708static int __init setup_hrtimer_hres(char *str)
709{
710 return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
711}
712
713__setup("highres=", setup_hrtimer_hres);
714
715/*
716 * hrtimer_high_res_enabled - query, if the highres mode is enabled
717 */
718static inline int hrtimer_is_hres_enabled(void)
719{
720 return hrtimer_hres_enabled;
721}
722
723/*
724 * Retrigger next event is called after clock was set
725 *
726 * Called with interrupts disabled via on_each_cpu()
727 */
728static void retrigger_next_event(void *arg)
729{
730 struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
731
732 if (!__hrtimer_hres_active(base))
733 return;
734
735 raw_spin_lock(&base->lock);
736 hrtimer_update_base(base);
737 hrtimer_force_reprogram(base, 0);
738 raw_spin_unlock(&base->lock);
739}
740
741/*
742 * Switch to high resolution mode
743 */
744static void hrtimer_switch_to_hres(void)
745{
746 struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
747
748 if (tick_init_highres()) {
749 pr_warn("Could not switch to high resolution mode on CPU %u\n",
750 base->cpu);
751 return;
752 }
753 base->hres_active = 1;
754 hrtimer_resolution = HIGH_RES_NSEC;
755
756 tick_setup_sched_timer();
757 /* "Retrigger" the interrupt to get things going */
758 retrigger_next_event(NULL);
759}
760
761static void clock_was_set_work(struct work_struct *work)
762{
763 clock_was_set();
764}
765
766static DECLARE_WORK(hrtimer_work, clock_was_set_work);
767
768/*
769 * Called from timekeeping and resume code to reprogram the hrtimer
770 * interrupt device on all cpus.
771 */
772void clock_was_set_delayed(void)
773{
774 schedule_work(&hrtimer_work);
775}
776
777#else
778
779static inline int hrtimer_is_hres_enabled(void) { return 0; }
780static inline void hrtimer_switch_to_hres(void) { }
781static inline void retrigger_next_event(void *arg) { }
782
783#endif /* CONFIG_HIGH_RES_TIMERS */
784
785/*
786 * When a timer is enqueued and expires earlier than the already enqueued
787 * timers, we have to check, whether it expires earlier than the timer for
788 * which the clock event device was armed.
789 *
790 * Called with interrupts disabled and base->cpu_base.lock held
791 */
792static void hrtimer_reprogram(struct hrtimer *timer, bool reprogram)
793{
794 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
795 struct hrtimer_clock_base *base = timer->base;
796 ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
797
798 WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
799
800 /*
801 * CLOCK_REALTIME timer might be requested with an absolute
802 * expiry time which is less than base->offset. Set it to 0.
803 */
804 if (expires < 0)
805 expires = 0;
806
807 if (timer->is_soft) {
808 /*
809 * soft hrtimer could be started on a remote CPU. In this
810 * case softirq_expires_next needs to be updated on the
811 * remote CPU. The soft hrtimer will not expire before the
812 * first hard hrtimer on the remote CPU -
813 * hrtimer_check_target() prevents this case.
814 */
815 struct hrtimer_cpu_base *timer_cpu_base = base->cpu_base;
816
817 if (timer_cpu_base->softirq_activated)
818 return;
819
820 if (!ktime_before(expires, timer_cpu_base->softirq_expires_next))
821 return;
822
823 timer_cpu_base->softirq_next_timer = timer;
824 timer_cpu_base->softirq_expires_next = expires;
825
826 if (!ktime_before(expires, timer_cpu_base->expires_next) ||
827 !reprogram)
828 return;
829 }
830
831 /*
832 * If the timer is not on the current cpu, we cannot reprogram
833 * the other cpus clock event device.
834 */
835 if (base->cpu_base != cpu_base)
836 return;
837
838 /*
839 * If the hrtimer interrupt is running, then it will
840 * reevaluate the clock bases and reprogram the clock event
841 * device. The callbacks are always executed in hard interrupt
842 * context so we don't need an extra check for a running
843 * callback.
844 */
845 if (cpu_base->in_hrtirq)
846 return;
847
848 if (expires >= cpu_base->expires_next)
849 return;
850
851 /* Update the pointer to the next expiring timer */
852 cpu_base->next_timer = timer;
853 cpu_base->expires_next = expires;
854
855 /*
856 * If hres is not active, hardware does not have to be
857 * programmed yet.
858 *
859 * If a hang was detected in the last timer interrupt then we
860 * do not schedule a timer which is earlier than the expiry
861 * which we enforced in the hang detection. We want the system
862 * to make progress.
863 */
864 if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
865 return;
866
867 /*
868 * Program the timer hardware. We enforce the expiry for
869 * events which are already in the past.
870 */
871 tick_program_event(expires, 1);
872}
873
874/*
875 * Clock realtime was set
876 *
877 * Change the offset of the realtime clock vs. the monotonic
878 * clock.
879 *
880 * We might have to reprogram the high resolution timer interrupt. On
881 * SMP we call the architecture specific code to retrigger _all_ high
882 * resolution timer interrupts. On UP we just disable interrupts and
883 * call the high resolution interrupt code.
884 */
885void clock_was_set(void)
886{
887#ifdef CONFIG_HIGH_RES_TIMERS
888 /* Retrigger the CPU local events everywhere */
889 on_each_cpu(retrigger_next_event, NULL, 1);
890#endif
891 timerfd_clock_was_set();
892}
893
894/*
895 * During resume we might have to reprogram the high resolution timer
896 * interrupt on all online CPUs. However, all other CPUs will be
897 * stopped with IRQs interrupts disabled so the clock_was_set() call
898 * must be deferred.
899 */
900void hrtimers_resume(void)
901{
902 lockdep_assert_irqs_disabled();
903 /* Retrigger on the local CPU */
904 retrigger_next_event(NULL);
905 /* And schedule a retrigger for all others */
906 clock_was_set_delayed();
907}
908
909/*
910 * Counterpart to lock_hrtimer_base above:
911 */
912static inline
913void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
914{
915 raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
916}
917
918/**
919 * hrtimer_forward - forward the timer expiry
920 * @timer: hrtimer to forward
921 * @now: forward past this time
922 * @interval: the interval to forward
923 *
924 * Forward the timer expiry so it will expire in the future.
925 * Returns the number of overruns.
926 *
927 * Can be safely called from the callback function of @timer. If
928 * called from other contexts @timer must neither be enqueued nor
929 * running the callback and the caller needs to take care of
930 * serialization.
931 *
932 * Note: This only updates the timer expiry value and does not requeue
933 * the timer.
934 */
935u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
936{
937 u64 orun = 1;
938 ktime_t delta;
939
940 delta = ktime_sub(now, hrtimer_get_expires(timer));
941
942 if (delta < 0)
943 return 0;
944
945 if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
946 return 0;
947
948 if (interval < hrtimer_resolution)
949 interval = hrtimer_resolution;
950
951 if (unlikely(delta >= interval)) {
952 s64 incr = ktime_to_ns(interval);
953
954 orun = ktime_divns(delta, incr);
955 hrtimer_add_expires_ns(timer, incr * orun);
956 if (hrtimer_get_expires_tv64(timer) > now)
957 return orun;
958 /*
959 * This (and the ktime_add() below) is the
960 * correction for exact:
961 */
962 orun++;
963 }
964 hrtimer_add_expires(timer, interval);
965
966 return orun;
967}
968EXPORT_SYMBOL_GPL(hrtimer_forward);
969
970/*
971 * enqueue_hrtimer - internal function to (re)start a timer
972 *
973 * The timer is inserted in expiry order. Insertion into the
974 * red black tree is O(log(n)). Must hold the base lock.
975 *
976 * Returns 1 when the new timer is the leftmost timer in the tree.
977 */
978static int enqueue_hrtimer(struct hrtimer *timer,
979 struct hrtimer_clock_base *base,
980 enum hrtimer_mode mode)
981{
982 debug_activate(timer, mode);
983
984 base->cpu_base->active_bases |= 1 << base->index;
985
986 /* Pairs with the lockless read in hrtimer_is_queued() */
987 WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
988
989 return timerqueue_add(&base->active, &timer->node);
990}
991
992/*
993 * __remove_hrtimer - internal function to remove a timer
994 *
995 * Caller must hold the base lock.
996 *
997 * High resolution timer mode reprograms the clock event device when the
998 * timer is the one which expires next. The caller can disable this by setting
999 * reprogram to zero. This is useful, when the context does a reprogramming
1000 * anyway (e.g. timer interrupt)
1001 */
1002static void __remove_hrtimer(struct hrtimer *timer,
1003 struct hrtimer_clock_base *base,
1004 u8 newstate, int reprogram)
1005{
1006 struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1007 u8 state = timer->state;
1008
1009 /* Pairs with the lockless read in hrtimer_is_queued() */
1010 WRITE_ONCE(timer->state, newstate);
1011 if (!(state & HRTIMER_STATE_ENQUEUED))
1012 return;
1013
1014 if (!timerqueue_del(&base->active, &timer->node))
1015 cpu_base->active_bases &= ~(1 << base->index);
1016
1017 /*
1018 * Note: If reprogram is false we do not update
1019 * cpu_base->next_timer. This happens when we remove the first
1020 * timer on a remote cpu. No harm as we never dereference
1021 * cpu_base->next_timer. So the worst thing what can happen is
1022 * an superfluous call to hrtimer_force_reprogram() on the
1023 * remote cpu later on if the same timer gets enqueued again.
1024 */
1025 if (reprogram && timer == cpu_base->next_timer)
1026 hrtimer_force_reprogram(cpu_base, 1);
1027}
1028
1029/*
1030 * remove hrtimer, called with base lock held
1031 */
1032static inline int
1033remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool restart)
1034{
1035 u8 state = timer->state;
1036
1037 if (state & HRTIMER_STATE_ENQUEUED) {
1038 int reprogram;
1039
1040 /*
1041 * Remove the timer and force reprogramming when high
1042 * resolution mode is active and the timer is on the current
1043 * CPU. If we remove a timer on another CPU, reprogramming is
1044 * skipped. The interrupt event on this CPU is fired and
1045 * reprogramming happens in the interrupt handler. This is a
1046 * rare case and less expensive than a smp call.
1047 */
1048 debug_deactivate(timer);
1049 reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1050
1051 if (!restart)
1052 state = HRTIMER_STATE_INACTIVE;
1053
1054 __remove_hrtimer(timer, base, state, reprogram);
1055 return 1;
1056 }
1057 return 0;
1058}
1059
1060static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
1061 const enum hrtimer_mode mode)
1062{
1063#ifdef CONFIG_TIME_LOW_RES
1064 /*
1065 * CONFIG_TIME_LOW_RES indicates that the system has no way to return
1066 * granular time values. For relative timers we add hrtimer_resolution
1067 * (i.e. one jiffie) to prevent short timeouts.
1068 */
1069 timer->is_rel = mode & HRTIMER_MODE_REL;
1070 if (timer->is_rel)
1071 tim = ktime_add_safe(tim, hrtimer_resolution);
1072#endif
1073 return tim;
1074}
1075
1076static void
1077hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
1078{
1079 ktime_t expires;
1080
1081 /*
1082 * Find the next SOFT expiration.
1083 */
1084 expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
1085
1086 /*
1087 * reprogramming needs to be triggered, even if the next soft
1088 * hrtimer expires at the same time than the next hard
1089 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
1090 */
1091 if (expires == KTIME_MAX)
1092 return;
1093
1094 /*
1095 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
1096 * cpu_base->*expires_next is only set by hrtimer_reprogram()
1097 */
1098 hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
1099}
1100
1101static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1102 u64 delta_ns, const enum hrtimer_mode mode,
1103 struct hrtimer_clock_base *base)
1104{
1105 struct hrtimer_clock_base *new_base;
1106
1107 /* Remove an active timer from the queue: */
1108 remove_hrtimer(timer, base, true);
1109
1110 if (mode & HRTIMER_MODE_REL)
1111 tim = ktime_add_safe(tim, base->get_time());
1112
1113 tim = hrtimer_update_lowres(timer, tim, mode);
1114
1115 hrtimer_set_expires_range_ns(timer, tim, delta_ns);
1116
1117 /* Switch the timer base, if necessary: */
1118 new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
1119
1120 return enqueue_hrtimer(timer, new_base, mode);
1121}
1122
1123/**
1124 * hrtimer_start_range_ns - (re)start an hrtimer
1125 * @timer: the timer to be added
1126 * @tim: expiry time
1127 * @delta_ns: "slack" range for the timer
1128 * @mode: timer mode: absolute (HRTIMER_MODE_ABS) or
1129 * relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
1130 * softirq based mode is considered for debug purpose only!
1131 */
1132void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1133 u64 delta_ns, const enum hrtimer_mode mode)
1134{
1135 struct hrtimer_clock_base *base;
1136 unsigned long flags;
1137
1138 /*
1139 * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
1140 * match on CONFIG_PREEMPT_RT = n. With PREEMPT_RT check the hard
1141 * expiry mode because unmarked timers are moved to softirq expiry.
1142 */
1143 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
1144 WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
1145 else
1146 WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard);
1147
1148 base = lock_hrtimer_base(timer, &flags);
1149
1150 if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
1151 hrtimer_reprogram(timer, true);
1152
1153 unlock_hrtimer_base(timer, &flags);
1154}
1155EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1156
1157/**
1158 * hrtimer_try_to_cancel - try to deactivate a timer
1159 * @timer: hrtimer to stop
1160 *
1161 * Returns:
1162 *
1163 * * 0 when the timer was not active
1164 * * 1 when the timer was active
1165 * * -1 when the timer is currently executing the callback function and
1166 * cannot be stopped
1167 */
1168int hrtimer_try_to_cancel(struct hrtimer *timer)
1169{
1170 struct hrtimer_clock_base *base;
1171 unsigned long flags;
1172 int ret = -1;
1173
1174 /*
1175 * Check lockless first. If the timer is not active (neither
1176 * enqueued nor running the callback, nothing to do here. The
1177 * base lock does not serialize against a concurrent enqueue,
1178 * so we can avoid taking it.
1179 */
1180 if (!hrtimer_active(timer))
1181 return 0;
1182
1183 base = lock_hrtimer_base(timer, &flags);
1184
1185 if (!hrtimer_callback_running(timer))
1186 ret = remove_hrtimer(timer, base, false);
1187
1188 unlock_hrtimer_base(timer, &flags);
1189
1190 return ret;
1191
1192}
1193EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1194
1195#ifdef CONFIG_PREEMPT_RT
1196static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
1197{
1198 spin_lock_init(&base->softirq_expiry_lock);
1199}
1200
1201static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
1202{
1203 spin_lock(&base->softirq_expiry_lock);
1204}
1205
1206static void hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base)
1207{
1208 spin_unlock(&base->softirq_expiry_lock);
1209}
1210
1211/*
1212 * The counterpart to hrtimer_cancel_wait_running().
1213 *
1214 * If there is a waiter for cpu_base->expiry_lock, then it was waiting for
1215 * the timer callback to finish. Drop expiry_lock and reacquire it. That
1216 * allows the waiter to acquire the lock and make progress.
1217 */
1218static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base,
1219 unsigned long flags)
1220{
1221 if (atomic_read(&cpu_base->timer_waiters)) {
1222 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1223 spin_unlock(&cpu_base->softirq_expiry_lock);
1224 spin_lock(&cpu_base->softirq_expiry_lock);
1225 raw_spin_lock_irq(&cpu_base->lock);
1226 }
1227}
1228
1229/*
1230 * This function is called on PREEMPT_RT kernels when the fast path
1231 * deletion of a timer failed because the timer callback function was
1232 * running.
1233 *
1234 * This prevents priority inversion: if the soft irq thread is preempted
1235 * in the middle of a timer callback, then calling del_timer_sync() can
1236 * lead to two issues:
1237 *
1238 * - If the caller is on a remote CPU then it has to spin wait for the timer
1239 * handler to complete. This can result in unbound priority inversion.
1240 *
1241 * - If the caller originates from the task which preempted the timer
1242 * handler on the same CPU, then spin waiting for the timer handler to
1243 * complete is never going to end.
1244 */
1245void hrtimer_cancel_wait_running(const struct hrtimer *timer)
1246{
1247 /* Lockless read. Prevent the compiler from reloading it below */
1248 struct hrtimer_clock_base *base = READ_ONCE(timer->base);
1249
1250 /*
1251 * Just relax if the timer expires in hard interrupt context or if
1252 * it is currently on the migration base.
1253 */
1254 if (!timer->is_soft || is_migration_base(base)) {
1255 cpu_relax();
1256 return;
1257 }
1258
1259 /*
1260 * Mark the base as contended and grab the expiry lock, which is
1261 * held by the softirq across the timer callback. Drop the lock
1262 * immediately so the softirq can expire the next timer. In theory
1263 * the timer could already be running again, but that's more than
1264 * unlikely and just causes another wait loop.
1265 */
1266 atomic_inc(&base->cpu_base->timer_waiters);
1267 spin_lock_bh(&base->cpu_base->softirq_expiry_lock);
1268 atomic_dec(&base->cpu_base->timer_waiters);
1269 spin_unlock_bh(&base->cpu_base->softirq_expiry_lock);
1270}
1271#else
1272static inline void
1273hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
1274static inline void
1275hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
1276static inline void
1277hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
1278static inline void hrtimer_sync_wait_running(struct hrtimer_cpu_base *base,
1279 unsigned long flags) { }
1280#endif
1281
1282/**
1283 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1284 * @timer: the timer to be cancelled
1285 *
1286 * Returns:
1287 * 0 when the timer was not active
1288 * 1 when the timer was active
1289 */
1290int hrtimer_cancel(struct hrtimer *timer)
1291{
1292 int ret;
1293
1294 do {
1295 ret = hrtimer_try_to_cancel(timer);
1296
1297 if (ret < 0)
1298 hrtimer_cancel_wait_running(timer);
1299 } while (ret < 0);
1300 return ret;
1301}
1302EXPORT_SYMBOL_GPL(hrtimer_cancel);
1303
1304/**
1305 * __hrtimer_get_remaining - get remaining time for the timer
1306 * @timer: the timer to read
1307 * @adjust: adjust relative timers when CONFIG_TIME_LOW_RES=y
1308 */
1309ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
1310{
1311 unsigned long flags;
1312 ktime_t rem;
1313
1314 lock_hrtimer_base(timer, &flags);
1315 if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
1316 rem = hrtimer_expires_remaining_adjusted(timer);
1317 else
1318 rem = hrtimer_expires_remaining(timer);
1319 unlock_hrtimer_base(timer, &flags);
1320
1321 return rem;
1322}
1323EXPORT_SYMBOL_GPL(__hrtimer_get_remaining);
1324
1325#ifdef CONFIG_NO_HZ_COMMON
1326/**
1327 * hrtimer_get_next_event - get the time until next expiry event
1328 *
1329 * Returns the next expiry time or KTIME_MAX if no timer is pending.
1330 */
1331u64 hrtimer_get_next_event(void)
1332{
1333 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1334 u64 expires = KTIME_MAX;
1335 unsigned long flags;
1336
1337 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1338
1339 if (!__hrtimer_hres_active(cpu_base))
1340 expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
1341
1342 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1343
1344 return expires;
1345}
1346
1347/**
1348 * hrtimer_next_event_without - time until next expiry event w/o one timer
1349 * @exclude: timer to exclude
1350 *
1351 * Returns the next expiry time over all timers except for the @exclude one or
1352 * KTIME_MAX if none of them is pending.
1353 */
1354u64 hrtimer_next_event_without(const struct hrtimer *exclude)
1355{
1356 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1357 u64 expires = KTIME_MAX;
1358 unsigned long flags;
1359
1360 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1361
1362 if (__hrtimer_hres_active(cpu_base)) {
1363 unsigned int active;
1364
1365 if (!cpu_base->softirq_activated) {
1366 active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
1367 expires = __hrtimer_next_event_base(cpu_base, exclude,
1368 active, KTIME_MAX);
1369 }
1370 active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
1371 expires = __hrtimer_next_event_base(cpu_base, exclude, active,
1372 expires);
1373 }
1374
1375 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1376
1377 return expires;
1378}
1379#endif
1380
1381static inline int hrtimer_clockid_to_base(clockid_t clock_id)
1382{
1383 if (likely(clock_id < MAX_CLOCKS)) {
1384 int base = hrtimer_clock_to_base_table[clock_id];
1385
1386 if (likely(base != HRTIMER_MAX_CLOCK_BASES))
1387 return base;
1388 }
1389 WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
1390 return HRTIMER_BASE_MONOTONIC;
1391}
1392
1393static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1394 enum hrtimer_mode mode)
1395{
1396 bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
1397 struct hrtimer_cpu_base *cpu_base;
1398 int base;
1399
1400 /*
1401 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1402 * marked for hard interrupt expiry mode are moved into soft
1403 * interrupt context for latency reasons and because the callbacks
1404 * can invoke functions which might sleep on RT, e.g. spin_lock().
1405 */
1406 if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD))
1407 softtimer = true;
1408
1409 memset(timer, 0, sizeof(struct hrtimer));
1410
1411 cpu_base = raw_cpu_ptr(&hrtimer_bases);
1412
1413 /*
1414 * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
1415 * clock modifications, so they needs to become CLOCK_MONOTONIC to
1416 * ensure POSIX compliance.
1417 */
1418 if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
1419 clock_id = CLOCK_MONOTONIC;
1420
1421 base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
1422 base += hrtimer_clockid_to_base(clock_id);
1423 timer->is_soft = softtimer;
1424 timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
1425 timer->base = &cpu_base->clock_base[base];
1426 timerqueue_init(&timer->node);
1427}
1428
1429/**
1430 * hrtimer_init - initialize a timer to the given clock
1431 * @timer: the timer to be initialized
1432 * @clock_id: the clock to be used
1433 * @mode: The modes which are relevant for initialization:
1434 * HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
1435 * HRTIMER_MODE_REL_SOFT
1436 *
1437 * The PINNED variants of the above can be handed in,
1438 * but the PINNED bit is ignored as pinning happens
1439 * when the hrtimer is started
1440 */
1441void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1442 enum hrtimer_mode mode)
1443{
1444 debug_init(timer, clock_id, mode);
1445 __hrtimer_init(timer, clock_id, mode);
1446}
1447EXPORT_SYMBOL_GPL(hrtimer_init);
1448
1449/*
1450 * A timer is active, when it is enqueued into the rbtree or the
1451 * callback function is running or it's in the state of being migrated
1452 * to another cpu.
1453 *
1454 * It is important for this function to not return a false negative.
1455 */
1456bool hrtimer_active(const struct hrtimer *timer)
1457{
1458 struct hrtimer_clock_base *base;
1459 unsigned int seq;
1460
1461 do {
1462 base = READ_ONCE(timer->base);
1463 seq = raw_read_seqcount_begin(&base->seq);
1464
1465 if (timer->state != HRTIMER_STATE_INACTIVE ||
1466 base->running == timer)
1467 return true;
1468
1469 } while (read_seqcount_retry(&base->seq, seq) ||
1470 base != READ_ONCE(timer->base));
1471
1472 return false;
1473}
1474EXPORT_SYMBOL_GPL(hrtimer_active);
1475
1476/*
1477 * The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
1478 * distinct sections:
1479 *
1480 * - queued: the timer is queued
1481 * - callback: the timer is being ran
1482 * - post: the timer is inactive or (re)queued
1483 *
1484 * On the read side we ensure we observe timer->state and cpu_base->running
1485 * from the same section, if anything changed while we looked at it, we retry.
1486 * This includes timer->base changing because sequence numbers alone are
1487 * insufficient for that.
1488 *
1489 * The sequence numbers are required because otherwise we could still observe
1490 * a false negative if the read side got smeared over multiple consecutive
1491 * __run_hrtimer() invocations.
1492 */
1493
1494static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
1495 struct hrtimer_clock_base *base,
1496 struct hrtimer *timer, ktime_t *now,
1497 unsigned long flags) __must_hold(&cpu_base->lock)
1498{
1499 enum hrtimer_restart (*fn)(struct hrtimer *);
1500 bool expires_in_hardirq;
1501 int restart;
1502
1503 lockdep_assert_held(&cpu_base->lock);
1504
1505 debug_deactivate(timer);
1506 base->running = timer;
1507
1508 /*
1509 * Separate the ->running assignment from the ->state assignment.
1510 *
1511 * As with a regular write barrier, this ensures the read side in
1512 * hrtimer_active() cannot observe base->running == NULL &&
1513 * timer->state == INACTIVE.
1514 */
1515 raw_write_seqcount_barrier(&base->seq);
1516
1517 __remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
1518 fn = timer->function;
1519
1520 /*
1521 * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
1522 * timer is restarted with a period then it becomes an absolute
1523 * timer. If its not restarted it does not matter.
1524 */
1525 if (IS_ENABLED(CONFIG_TIME_LOW_RES))
1526 timer->is_rel = false;
1527
1528 /*
1529 * The timer is marked as running in the CPU base, so it is
1530 * protected against migration to a different CPU even if the lock
1531 * is dropped.
1532 */
1533 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1534 trace_hrtimer_expire_entry(timer, now);
1535 expires_in_hardirq = lockdep_hrtimer_enter(timer);
1536
1537 restart = fn(timer);
1538
1539 lockdep_hrtimer_exit(expires_in_hardirq);
1540 trace_hrtimer_expire_exit(timer);
1541 raw_spin_lock_irq(&cpu_base->lock);
1542
1543 /*
1544 * Note: We clear the running state after enqueue_hrtimer and
1545 * we do not reprogram the event hardware. Happens either in
1546 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1547 *
1548 * Note: Because we dropped the cpu_base->lock above,
1549 * hrtimer_start_range_ns() can have popped in and enqueued the timer
1550 * for us already.
1551 */
1552 if (restart != HRTIMER_NORESTART &&
1553 !(timer->state & HRTIMER_STATE_ENQUEUED))
1554 enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
1555
1556 /*
1557 * Separate the ->running assignment from the ->state assignment.
1558 *
1559 * As with a regular write barrier, this ensures the read side in
1560 * hrtimer_active() cannot observe base->running.timer == NULL &&
1561 * timer->state == INACTIVE.
1562 */
1563 raw_write_seqcount_barrier(&base->seq);
1564
1565 WARN_ON_ONCE(base->running != timer);
1566 base->running = NULL;
1567}
1568
1569static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
1570 unsigned long flags, unsigned int active_mask)
1571{
1572 struct hrtimer_clock_base *base;
1573 unsigned int active = cpu_base->active_bases & active_mask;
1574
1575 for_each_active_base(base, cpu_base, active) {
1576 struct timerqueue_node *node;
1577 ktime_t basenow;
1578
1579 basenow = ktime_add(now, base->offset);
1580
1581 while ((node = timerqueue_getnext(&base->active))) {
1582 struct hrtimer *timer;
1583
1584 timer = container_of(node, struct hrtimer, node);
1585
1586 /*
1587 * The immediate goal for using the softexpires is
1588 * minimizing wakeups, not running timers at the
1589 * earliest interrupt after their soft expiration.
1590 * This allows us to avoid using a Priority Search
1591 * Tree, which can answer a stabbing query for
1592 * overlapping intervals and instead use the simple
1593 * BST we already have.
1594 * We don't add extra wakeups by delaying timers that
1595 * are right-of a not yet expired timer, because that
1596 * timer will have to trigger a wakeup anyway.
1597 */
1598 if (basenow < hrtimer_get_softexpires_tv64(timer))
1599 break;
1600
1601 __run_hrtimer(cpu_base, base, timer, &basenow, flags);
1602 if (active_mask == HRTIMER_ACTIVE_SOFT)
1603 hrtimer_sync_wait_running(cpu_base, flags);
1604 }
1605 }
1606}
1607
1608static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
1609{
1610 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1611 unsigned long flags;
1612 ktime_t now;
1613
1614 hrtimer_cpu_base_lock_expiry(cpu_base);
1615 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1616
1617 now = hrtimer_update_base(cpu_base);
1618 __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
1619
1620 cpu_base->softirq_activated = 0;
1621 hrtimer_update_softirq_timer(cpu_base, true);
1622
1623 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1624 hrtimer_cpu_base_unlock_expiry(cpu_base);
1625}
1626
1627#ifdef CONFIG_HIGH_RES_TIMERS
1628
1629/*
1630 * High resolution timer interrupt
1631 * Called with interrupts disabled
1632 */
1633void hrtimer_interrupt(struct clock_event_device *dev)
1634{
1635 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1636 ktime_t expires_next, now, entry_time, delta;
1637 unsigned long flags;
1638 int retries = 0;
1639
1640 BUG_ON(!cpu_base->hres_active);
1641 cpu_base->nr_events++;
1642 dev->next_event = KTIME_MAX;
1643
1644 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1645 entry_time = now = hrtimer_update_base(cpu_base);
1646retry:
1647 cpu_base->in_hrtirq = 1;
1648 /*
1649 * We set expires_next to KTIME_MAX here with cpu_base->lock
1650 * held to prevent that a timer is enqueued in our queue via
1651 * the migration code. This does not affect enqueueing of
1652 * timers which run their callback and need to be requeued on
1653 * this CPU.
1654 */
1655 cpu_base->expires_next = KTIME_MAX;
1656
1657 if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1658 cpu_base->softirq_expires_next = KTIME_MAX;
1659 cpu_base->softirq_activated = 1;
1660 raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1661 }
1662
1663 __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1664
1665 /* Reevaluate the clock bases for the [soft] next expiry */
1666 expires_next = hrtimer_update_next_event(cpu_base);
1667 /*
1668 * Store the new expiry value so the migration code can verify
1669 * against it.
1670 */
1671 cpu_base->expires_next = expires_next;
1672 cpu_base->in_hrtirq = 0;
1673 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1674
1675 /* Reprogramming necessary ? */
1676 if (!tick_program_event(expires_next, 0)) {
1677 cpu_base->hang_detected = 0;
1678 return;
1679 }
1680
1681 /*
1682 * The next timer was already expired due to:
1683 * - tracing
1684 * - long lasting callbacks
1685 * - being scheduled away when running in a VM
1686 *
1687 * We need to prevent that we loop forever in the hrtimer
1688 * interrupt routine. We give it 3 attempts to avoid
1689 * overreacting on some spurious event.
1690 *
1691 * Acquire base lock for updating the offsets and retrieving
1692 * the current time.
1693 */
1694 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1695 now = hrtimer_update_base(cpu_base);
1696 cpu_base->nr_retries++;
1697 if (++retries < 3)
1698 goto retry;
1699 /*
1700 * Give the system a chance to do something else than looping
1701 * here. We stored the entry time, so we know exactly how long
1702 * we spent here. We schedule the next event this amount of
1703 * time away.
1704 */
1705 cpu_base->nr_hangs++;
1706 cpu_base->hang_detected = 1;
1707 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1708
1709 delta = ktime_sub(now, entry_time);
1710 if ((unsigned int)delta > cpu_base->max_hang_time)
1711 cpu_base->max_hang_time = (unsigned int) delta;
1712 /*
1713 * Limit it to a sensible value as we enforce a longer
1714 * delay. Give the CPU at least 100ms to catch up.
1715 */
1716 if (delta > 100 * NSEC_PER_MSEC)
1717 expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1718 else
1719 expires_next = ktime_add(now, delta);
1720 tick_program_event(expires_next, 1);
1721 pr_warn_once("hrtimer: interrupt took %llu ns\n", ktime_to_ns(delta));
1722}
1723
1724/* called with interrupts disabled */
1725static inline void __hrtimer_peek_ahead_timers(void)
1726{
1727 struct tick_device *td;
1728
1729 if (!hrtimer_hres_active())
1730 return;
1731
1732 td = this_cpu_ptr(&tick_cpu_device);
1733 if (td && td->evtdev)
1734 hrtimer_interrupt(td->evtdev);
1735}
1736
1737#else /* CONFIG_HIGH_RES_TIMERS */
1738
1739static inline void __hrtimer_peek_ahead_timers(void) { }
1740
1741#endif /* !CONFIG_HIGH_RES_TIMERS */
1742
1743/*
1744 * Called from run_local_timers in hardirq context every jiffy
1745 */
1746void hrtimer_run_queues(void)
1747{
1748 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1749 unsigned long flags;
1750 ktime_t now;
1751
1752 if (__hrtimer_hres_active(cpu_base))
1753 return;
1754
1755 /*
1756 * This _is_ ugly: We have to check periodically, whether we
1757 * can switch to highres and / or nohz mode. The clocksource
1758 * switch happens with xtime_lock held. Notification from
1759 * there only sets the check bit in the tick_oneshot code,
1760 * otherwise we might deadlock vs. xtime_lock.
1761 */
1762 if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
1763 hrtimer_switch_to_hres();
1764 return;
1765 }
1766
1767 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1768 now = hrtimer_update_base(cpu_base);
1769
1770 if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1771 cpu_base->softirq_expires_next = KTIME_MAX;
1772 cpu_base->softirq_activated = 1;
1773 raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1774 }
1775
1776 __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1777 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1778}
1779
1780/*
1781 * Sleep related functions:
1782 */
1783static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1784{
1785 struct hrtimer_sleeper *t =
1786 container_of(timer, struct hrtimer_sleeper, timer);
1787 struct task_struct *task = t->task;
1788
1789 t->task = NULL;
1790 if (task)
1791 wake_up_process(task);
1792
1793 return HRTIMER_NORESTART;
1794}
1795
1796/**
1797 * hrtimer_sleeper_start_expires - Start a hrtimer sleeper timer
1798 * @sl: sleeper to be started
1799 * @mode: timer mode abs/rel
1800 *
1801 * Wrapper around hrtimer_start_expires() for hrtimer_sleeper based timers
1802 * to allow PREEMPT_RT to tweak the delivery mode (soft/hardirq context)
1803 */
1804void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
1805 enum hrtimer_mode mode)
1806{
1807 /*
1808 * Make the enqueue delivery mode check work on RT. If the sleeper
1809 * was initialized for hard interrupt delivery, force the mode bit.
1810 * This is a special case for hrtimer_sleepers because
1811 * hrtimer_init_sleeper() determines the delivery mode on RT so the
1812 * fiddling with this decision is avoided at the call sites.
1813 */
1814 if (IS_ENABLED(CONFIG_PREEMPT_RT) && sl->timer.is_hard)
1815 mode |= HRTIMER_MODE_HARD;
1816
1817 hrtimer_start_expires(&sl->timer, mode);
1818}
1819EXPORT_SYMBOL_GPL(hrtimer_sleeper_start_expires);
1820
1821static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
1822 clockid_t clock_id, enum hrtimer_mode mode)
1823{
1824 /*
1825 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1826 * marked for hard interrupt expiry mode are moved into soft
1827 * interrupt context either for latency reasons or because the
1828 * hrtimer callback takes regular spinlocks or invokes other
1829 * functions which are not suitable for hard interrupt context on
1830 * PREEMPT_RT.
1831 *
1832 * The hrtimer_sleeper callback is RT compatible in hard interrupt
1833 * context, but there is a latency concern: Untrusted userspace can
1834 * spawn many threads which arm timers for the same expiry time on
1835 * the same CPU. That causes a latency spike due to the wakeup of
1836 * a gazillion threads.
1837 *
1838 * OTOH, privileged real-time user space applications rely on the
1839 * low latency of hard interrupt wakeups. If the current task is in
1840 * a real-time scheduling class, mark the mode for hard interrupt
1841 * expiry.
1842 */
1843 if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
1844 if (task_is_realtime(current) && !(mode & HRTIMER_MODE_SOFT))
1845 mode |= HRTIMER_MODE_HARD;
1846 }
1847
1848 __hrtimer_init(&sl->timer, clock_id, mode);
1849 sl->timer.function = hrtimer_wakeup;
1850 sl->task = current;
1851}
1852
1853/**
1854 * hrtimer_init_sleeper - initialize sleeper to the given clock
1855 * @sl: sleeper to be initialized
1856 * @clock_id: the clock to be used
1857 * @mode: timer mode abs/rel
1858 */
1859void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
1860 enum hrtimer_mode mode)
1861{
1862 debug_init(&sl->timer, clock_id, mode);
1863 __hrtimer_init_sleeper(sl, clock_id, mode);
1864
1865}
1866EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
1867
1868int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
1869{
1870 switch(restart->nanosleep.type) {
1871#ifdef CONFIG_COMPAT_32BIT_TIME
1872 case TT_COMPAT:
1873 if (put_old_timespec32(ts, restart->nanosleep.compat_rmtp))
1874 return -EFAULT;
1875 break;
1876#endif
1877 case TT_NATIVE:
1878 if (put_timespec64(ts, restart->nanosleep.rmtp))
1879 return -EFAULT;
1880 break;
1881 default:
1882 BUG();
1883 }
1884 return -ERESTART_RESTARTBLOCK;
1885}
1886
1887static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
1888{
1889 struct restart_block *restart;
1890
1891 do {
1892 set_current_state(TASK_INTERRUPTIBLE);
1893 hrtimer_sleeper_start_expires(t, mode);
1894
1895 if (likely(t->task))
1896 freezable_schedule();
1897
1898 hrtimer_cancel(&t->timer);
1899 mode = HRTIMER_MODE_ABS;
1900
1901 } while (t->task && !signal_pending(current));
1902
1903 __set_current_state(TASK_RUNNING);
1904
1905 if (!t->task)
1906 return 0;
1907
1908 restart = &current->restart_block;
1909 if (restart->nanosleep.type != TT_NONE) {
1910 ktime_t rem = hrtimer_expires_remaining(&t->timer);
1911 struct timespec64 rmt;
1912
1913 if (rem <= 0)
1914 return 0;
1915 rmt = ktime_to_timespec64(rem);
1916
1917 return nanosleep_copyout(restart, &rmt);
1918 }
1919 return -ERESTART_RESTARTBLOCK;
1920}
1921
1922static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
1923{
1924 struct hrtimer_sleeper t;
1925 int ret;
1926
1927 hrtimer_init_sleeper_on_stack(&t, restart->nanosleep.clockid,
1928 HRTIMER_MODE_ABS);
1929 hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
1930 ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
1931 destroy_hrtimer_on_stack(&t.timer);
1932 return ret;
1933}
1934
1935long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
1936 const clockid_t clockid)
1937{
1938 struct restart_block *restart;
1939 struct hrtimer_sleeper t;
1940 int ret = 0;
1941 u64 slack;
1942
1943 slack = current->timer_slack_ns;
1944 if (dl_task(current) || rt_task(current))
1945 slack = 0;
1946
1947 hrtimer_init_sleeper_on_stack(&t, clockid, mode);
1948 hrtimer_set_expires_range_ns(&t.timer, rqtp, slack);
1949 ret = do_nanosleep(&t, mode);
1950 if (ret != -ERESTART_RESTARTBLOCK)
1951 goto out;
1952
1953 /* Absolute timers do not update the rmtp value and restart: */
1954 if (mode == HRTIMER_MODE_ABS) {
1955 ret = -ERESTARTNOHAND;
1956 goto out;
1957 }
1958
1959 restart = &current->restart_block;
1960 restart->nanosleep.clockid = t.timer.base->clockid;
1961 restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
1962 set_restart_fn(restart, hrtimer_nanosleep_restart);
1963out:
1964 destroy_hrtimer_on_stack(&t.timer);
1965 return ret;
1966}
1967
1968#ifdef CONFIG_64BIT
1969
1970SYSCALL_DEFINE2(nanosleep, struct __kernel_timespec __user *, rqtp,
1971 struct __kernel_timespec __user *, rmtp)
1972{
1973 struct timespec64 tu;
1974
1975 if (get_timespec64(&tu, rqtp))
1976 return -EFAULT;
1977
1978 if (!timespec64_valid(&tu))
1979 return -EINVAL;
1980
1981 current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
1982 current->restart_block.nanosleep.rmtp = rmtp;
1983 return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
1984 CLOCK_MONOTONIC);
1985}
1986
1987#endif
1988
1989#ifdef CONFIG_COMPAT_32BIT_TIME
1990
1991SYSCALL_DEFINE2(nanosleep_time32, struct old_timespec32 __user *, rqtp,
1992 struct old_timespec32 __user *, rmtp)
1993{
1994 struct timespec64 tu;
1995
1996 if (get_old_timespec32(&tu, rqtp))
1997 return -EFAULT;
1998
1999 if (!timespec64_valid(&tu))
2000 return -EINVAL;
2001
2002 current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
2003 current->restart_block.nanosleep.compat_rmtp = rmtp;
2004 return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2005 CLOCK_MONOTONIC);
2006}
2007#endif
2008
2009/*
2010 * Functions related to boot-time initialization:
2011 */
2012int hrtimers_prepare_cpu(unsigned int cpu)
2013{
2014 struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
2015 int i;
2016
2017 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2018 struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i];
2019
2020 clock_b->cpu_base = cpu_base;
2021 seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock);
2022 timerqueue_init_head(&clock_b->active);
2023 }
2024
2025 cpu_base->cpu = cpu;
2026 cpu_base->active_bases = 0;
2027 cpu_base->hres_active = 0;
2028 cpu_base->hang_detected = 0;
2029 cpu_base->next_timer = NULL;
2030 cpu_base->softirq_next_timer = NULL;
2031 cpu_base->expires_next = KTIME_MAX;
2032 cpu_base->softirq_expires_next = KTIME_MAX;
2033 hrtimer_cpu_base_init_expiry_lock(cpu_base);
2034 return 0;
2035}
2036
2037#ifdef CONFIG_HOTPLUG_CPU
2038
2039static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
2040 struct hrtimer_clock_base *new_base)
2041{
2042 struct hrtimer *timer;
2043 struct timerqueue_node *node;
2044
2045 while ((node = timerqueue_getnext(&old_base->active))) {
2046 timer = container_of(node, struct hrtimer, node);
2047 BUG_ON(hrtimer_callback_running(timer));
2048 debug_deactivate(timer);
2049
2050 /*
2051 * Mark it as ENQUEUED not INACTIVE otherwise the
2052 * timer could be seen as !active and just vanish away
2053 * under us on another CPU
2054 */
2055 __remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
2056 timer->base = new_base;
2057 /*
2058 * Enqueue the timers on the new cpu. This does not
2059 * reprogram the event device in case the timer
2060 * expires before the earliest on this CPU, but we run
2061 * hrtimer_interrupt after we migrated everything to
2062 * sort out already expired timers and reprogram the
2063 * event device.
2064 */
2065 enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
2066 }
2067}
2068
2069int hrtimers_dead_cpu(unsigned int scpu)
2070{
2071 struct hrtimer_cpu_base *old_base, *new_base;
2072 int i;
2073
2074 BUG_ON(cpu_online(scpu));
2075 tick_cancel_sched_timer(scpu);
2076
2077 /*
2078 * this BH disable ensures that raise_softirq_irqoff() does
2079 * not wakeup ksoftirqd (and acquire the pi-lock) while
2080 * holding the cpu_base lock
2081 */
2082 local_bh_disable();
2083 local_irq_disable();
2084 old_base = &per_cpu(hrtimer_bases, scpu);
2085 new_base = this_cpu_ptr(&hrtimer_bases);
2086 /*
2087 * The caller is globally serialized and nobody else
2088 * takes two locks at once, deadlock is not possible.
2089 */
2090 raw_spin_lock(&new_base->lock);
2091 raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
2092
2093 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2094 migrate_hrtimer_list(&old_base->clock_base[i],
2095 &new_base->clock_base[i]);
2096 }
2097
2098 /*
2099 * The migration might have changed the first expiring softirq
2100 * timer on this CPU. Update it.
2101 */
2102 hrtimer_update_softirq_timer(new_base, false);
2103
2104 raw_spin_unlock(&old_base->lock);
2105 raw_spin_unlock(&new_base->lock);
2106
2107 /* Check, if we got expired work to do */
2108 __hrtimer_peek_ahead_timers();
2109 local_irq_enable();
2110 local_bh_enable();
2111 return 0;
2112}
2113
2114#endif /* CONFIG_HOTPLUG_CPU */
2115
2116void __init hrtimers_init(void)
2117{
2118 hrtimers_prepare_cpu(smp_processor_id());
2119 open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
2120}
2121
2122/**
2123 * schedule_hrtimeout_range_clock - sleep until timeout
2124 * @expires: timeout value (ktime_t)
2125 * @delta: slack in expires timeout (ktime_t)
2126 * @mode: timer mode
2127 * @clock_id: timer clock to be used
2128 */
2129int __sched
2130schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
2131 const enum hrtimer_mode mode, clockid_t clock_id)
2132{
2133 struct hrtimer_sleeper t;
2134
2135 /*
2136 * Optimize when a zero timeout value is given. It does not
2137 * matter whether this is an absolute or a relative time.
2138 */
2139 if (expires && *expires == 0) {
2140 __set_current_state(TASK_RUNNING);
2141 return 0;
2142 }
2143
2144 /*
2145 * A NULL parameter means "infinite"
2146 */
2147 if (!expires) {
2148 schedule();
2149 return -EINTR;
2150 }
2151
2152 hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
2153 hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
2154 hrtimer_sleeper_start_expires(&t, mode);
2155
2156 if (likely(t.task))
2157 schedule();
2158
2159 hrtimer_cancel(&t.timer);
2160 destroy_hrtimer_on_stack(&t.timer);
2161
2162 __set_current_state(TASK_RUNNING);
2163
2164 return !t.task ? 0 : -EINTR;
2165}
2166
2167/**
2168 * schedule_hrtimeout_range - sleep until timeout
2169 * @expires: timeout value (ktime_t)
2170 * @delta: slack in expires timeout (ktime_t)
2171 * @mode: timer mode
2172 *
2173 * Make the current task sleep until the given expiry time has
2174 * elapsed. The routine will return immediately unless
2175 * the current task state has been set (see set_current_state()).
2176 *
2177 * The @delta argument gives the kernel the freedom to schedule the
2178 * actual wakeup to a time that is both power and performance friendly.
2179 * The kernel give the normal best effort behavior for "@expires+@delta",
2180 * but may decide to fire the timer earlier, but no earlier than @expires.
2181 *
2182 * You can set the task state as follows -
2183 *
2184 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2185 * pass before the routine returns unless the current task is explicitly
2186 * woken up, (e.g. by wake_up_process()).
2187 *
2188 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2189 * delivered to the current task or the current task is explicitly woken
2190 * up.
2191 *
2192 * The current task state is guaranteed to be TASK_RUNNING when this
2193 * routine returns.
2194 *
2195 * Returns 0 when the timer has expired. If the task was woken before the
2196 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2197 * by an explicit wakeup, it returns -EINTR.
2198 */
2199int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
2200 const enum hrtimer_mode mode)
2201{
2202 return schedule_hrtimeout_range_clock(expires, delta, mode,
2203 CLOCK_MONOTONIC);
2204}
2205EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
2206
2207/**
2208 * schedule_hrtimeout - sleep until timeout
2209 * @expires: timeout value (ktime_t)
2210 * @mode: timer mode
2211 *
2212 * Make the current task sleep until the given expiry time has
2213 * elapsed. The routine will return immediately unless
2214 * the current task state has been set (see set_current_state()).
2215 *
2216 * You can set the task state as follows -
2217 *
2218 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2219 * pass before the routine returns unless the current task is explicitly
2220 * woken up, (e.g. by wake_up_process()).
2221 *
2222 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2223 * delivered to the current task or the current task is explicitly woken
2224 * up.
2225 *
2226 * The current task state is guaranteed to be TASK_RUNNING when this
2227 * routine returns.
2228 *
2229 * Returns 0 when the timer has expired. If the task was woken before the
2230 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2231 * by an explicit wakeup, it returns -EINTR.
2232 */
2233int __sched schedule_hrtimeout(ktime_t *expires,
2234 const enum hrtimer_mode mode)
2235{
2236 return schedule_hrtimeout_range(expires, 0, mode);
2237}
2238EXPORT_SYMBOL_GPL(schedule_hrtimeout);