projects/linux·blob v5.19-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
655static void __hrtimer_reprogram(struct hrtimer_cpu_base *cpu_base,
656 struct hrtimer *next_timer,
657 ktime_t expires_next)
658{
659 cpu_base->expires_next = expires_next;
660
661 /*
662 * If hres is not active, hardware does not have to be
663 * reprogrammed yet.
664 *
665 * If a hang was detected in the last timer interrupt then we
666 * leave the hang delay active in the hardware. We want the
667 * system to make progress. That also prevents the following
668 * scenario:
669 * T1 expires 50ms from now
670 * T2 expires 5s from now
671 *
672 * T1 is removed, so this code is called and would reprogram
673 * the hardware to 5s from now. Any hrtimer_start after that
674 * will not reprogram the hardware due to hang_detected being
675 * set. So we'd effectively block all timers until the T2 event
676 * fires.
677 */
678 if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
679 return;
680
681 tick_program_event(expires_next, 1);
682}
683
684/*
685 * Reprogram the event source with checking both queues for the
686 * next event
687 * Called with interrupts disabled and base->lock held
688 */
689static void
690hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
691{
692 ktime_t expires_next;
693
694 expires_next = hrtimer_update_next_event(cpu_base);
695
696 if (skip_equal && expires_next == cpu_base->expires_next)
697 return;
698
699 __hrtimer_reprogram(cpu_base, cpu_base->next_timer, expires_next);
700}
701
702/* High resolution timer related functions */
703#ifdef CONFIG_HIGH_RES_TIMERS
704
705/*
706 * High resolution timer enabled ?
707 */
708static bool hrtimer_hres_enabled __read_mostly = true;
709unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
710EXPORT_SYMBOL_GPL(hrtimer_resolution);
711
712/*
713 * Enable / Disable high resolution mode
714 */
715static int __init setup_hrtimer_hres(char *str)
716{
717 return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
718}
719
720__setup("highres=", setup_hrtimer_hres);
721
722/*
723 * hrtimer_high_res_enabled - query, if the highres mode is enabled
724 */
725static inline int hrtimer_is_hres_enabled(void)
726{
727 return hrtimer_hres_enabled;
728}
729
730static void retrigger_next_event(void *arg);
731
732/*
733 * Switch to high resolution mode
734 */
735static void hrtimer_switch_to_hres(void)
736{
737 struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
738
739 if (tick_init_highres()) {
740 pr_warn("Could not switch to high resolution mode on CPU %u\n",
741 base->cpu);
742 return;
743 }
744 base->hres_active = 1;
745 hrtimer_resolution = HIGH_RES_NSEC;
746
747 tick_setup_sched_timer();
748 /* "Retrigger" the interrupt to get things going */
749 retrigger_next_event(NULL);
750}
751
752#else
753
754static inline int hrtimer_is_hres_enabled(void) { return 0; }
755static inline void hrtimer_switch_to_hres(void) { }
756
757#endif /* CONFIG_HIGH_RES_TIMERS */
758/*
759 * Retrigger next event is called after clock was set with interrupts
760 * disabled through an SMP function call or directly from low level
761 * resume code.
762 *
763 * This is only invoked when:
764 * - CONFIG_HIGH_RES_TIMERS is enabled.
765 * - CONFIG_NOHZ_COMMON is enabled
766 *
767 * For the other cases this function is empty and because the call sites
768 * are optimized out it vanishes as well, i.e. no need for lots of
769 * #ifdeffery.
770 */
771static void retrigger_next_event(void *arg)
772{
773 struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
774
775 /*
776 * When high resolution mode or nohz is active, then the offsets of
777 * CLOCK_REALTIME/TAI/BOOTTIME have to be updated. Otherwise the
778 * next tick will take care of that.
779 *
780 * If high resolution mode is active then the next expiring timer
781 * must be reevaluated and the clock event device reprogrammed if
782 * necessary.
783 *
784 * In the NOHZ case the update of the offset and the reevaluation
785 * of the next expiring timer is enough. The return from the SMP
786 * function call will take care of the reprogramming in case the
787 * CPU was in a NOHZ idle sleep.
788 */
789 if (!__hrtimer_hres_active(base) && !tick_nohz_active)
790 return;
791
792 raw_spin_lock(&base->lock);
793 hrtimer_update_base(base);
794 if (__hrtimer_hres_active(base))
795 hrtimer_force_reprogram(base, 0);
796 else
797 hrtimer_update_next_event(base);
798 raw_spin_unlock(&base->lock);
799}
800
801/*
802 * When a timer is enqueued and expires earlier than the already enqueued
803 * timers, we have to check, whether it expires earlier than the timer for
804 * which the clock event device was armed.
805 *
806 * Called with interrupts disabled and base->cpu_base.lock held
807 */
808static void hrtimer_reprogram(struct hrtimer *timer, bool reprogram)
809{
810 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
811 struct hrtimer_clock_base *base = timer->base;
812 ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
813
814 WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
815
816 /*
817 * CLOCK_REALTIME timer might be requested with an absolute
818 * expiry time which is less than base->offset. Set it to 0.
819 */
820 if (expires < 0)
821 expires = 0;
822
823 if (timer->is_soft) {
824 /*
825 * soft hrtimer could be started on a remote CPU. In this
826 * case softirq_expires_next needs to be updated on the
827 * remote CPU. The soft hrtimer will not expire before the
828 * first hard hrtimer on the remote CPU -
829 * hrtimer_check_target() prevents this case.
830 */
831 struct hrtimer_cpu_base *timer_cpu_base = base->cpu_base;
832
833 if (timer_cpu_base->softirq_activated)
834 return;
835
836 if (!ktime_before(expires, timer_cpu_base->softirq_expires_next))
837 return;
838
839 timer_cpu_base->softirq_next_timer = timer;
840 timer_cpu_base->softirq_expires_next = expires;
841
842 if (!ktime_before(expires, timer_cpu_base->expires_next) ||
843 !reprogram)
844 return;
845 }
846
847 /*
848 * If the timer is not on the current cpu, we cannot reprogram
849 * the other cpus clock event device.
850 */
851 if (base->cpu_base != cpu_base)
852 return;
853
854 if (expires >= cpu_base->expires_next)
855 return;
856
857 /*
858 * If the hrtimer interrupt is running, then it will reevaluate the
859 * clock bases and reprogram the clock event device.
860 */
861 if (cpu_base->in_hrtirq)
862 return;
863
864 cpu_base->next_timer = timer;
865
866 __hrtimer_reprogram(cpu_base, timer, expires);
867}
868
869static bool update_needs_ipi(struct hrtimer_cpu_base *cpu_base,
870 unsigned int active)
871{
872 struct hrtimer_clock_base *base;
873 unsigned int seq;
874 ktime_t expires;
875
876 /*
877 * Update the base offsets unconditionally so the following
878 * checks whether the SMP function call is required works.
879 *
880 * The update is safe even when the remote CPU is in the hrtimer
881 * interrupt or the hrtimer soft interrupt and expiring affected
882 * bases. Either it will see the update before handling a base or
883 * it will see it when it finishes the processing and reevaluates
884 * the next expiring timer.
885 */
886 seq = cpu_base->clock_was_set_seq;
887 hrtimer_update_base(cpu_base);
888
889 /*
890 * If the sequence did not change over the update then the
891 * remote CPU already handled it.
892 */
893 if (seq == cpu_base->clock_was_set_seq)
894 return false;
895
896 /*
897 * If the remote CPU is currently handling an hrtimer interrupt, it
898 * will reevaluate the first expiring timer of all clock bases
899 * before reprogramming. Nothing to do here.
900 */
901 if (cpu_base->in_hrtirq)
902 return false;
903
904 /*
905 * Walk the affected clock bases and check whether the first expiring
906 * timer in a clock base is moving ahead of the first expiring timer of
907 * @cpu_base. If so, the IPI must be invoked because per CPU clock
908 * event devices cannot be remotely reprogrammed.
909 */
910 active &= cpu_base->active_bases;
911
912 for_each_active_base(base, cpu_base, active) {
913 struct timerqueue_node *next;
914
915 next = timerqueue_getnext(&base->active);
916 expires = ktime_sub(next->expires, base->offset);
917 if (expires < cpu_base->expires_next)
918 return true;
919
920 /* Extra check for softirq clock bases */
921 if (base->clockid < HRTIMER_BASE_MONOTONIC_SOFT)
922 continue;
923 if (cpu_base->softirq_activated)
924 continue;
925 if (expires < cpu_base->softirq_expires_next)
926 return true;
927 }
928 return false;
929}
930
931/*
932 * Clock was set. This might affect CLOCK_REALTIME, CLOCK_TAI and
933 * CLOCK_BOOTTIME (for late sleep time injection).
934 *
935 * This requires to update the offsets for these clocks
936 * vs. CLOCK_MONOTONIC. When high resolution timers are enabled, then this
937 * also requires to eventually reprogram the per CPU clock event devices
938 * when the change moves an affected timer ahead of the first expiring
939 * timer on that CPU. Obviously remote per CPU clock event devices cannot
940 * be reprogrammed. The other reason why an IPI has to be sent is when the
941 * system is in !HIGH_RES and NOHZ mode. The NOHZ mode updates the offsets
942 * in the tick, which obviously might be stopped, so this has to bring out
943 * the remote CPU which might sleep in idle to get this sorted.
944 */
945void clock_was_set(unsigned int bases)
946{
947 struct hrtimer_cpu_base *cpu_base = raw_cpu_ptr(&hrtimer_bases);
948 cpumask_var_t mask;
949 int cpu;
950
951 if (!__hrtimer_hres_active(cpu_base) && !tick_nohz_active)
952 goto out_timerfd;
953
954 if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
955 on_each_cpu(retrigger_next_event, NULL, 1);
956 goto out_timerfd;
957 }
958
959 /* Avoid interrupting CPUs if possible */
960 cpus_read_lock();
961 for_each_online_cpu(cpu) {
962 unsigned long flags;
963
964 cpu_base = &per_cpu(hrtimer_bases, cpu);
965 raw_spin_lock_irqsave(&cpu_base->lock, flags);
966
967 if (update_needs_ipi(cpu_base, bases))
968 cpumask_set_cpu(cpu, mask);
969
970 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
971 }
972
973 preempt_disable();
974 smp_call_function_many(mask, retrigger_next_event, NULL, 1);
975 preempt_enable();
976 cpus_read_unlock();
977 free_cpumask_var(mask);
978
979out_timerfd:
980 timerfd_clock_was_set();
981}
982
983static void clock_was_set_work(struct work_struct *work)
984{
985 clock_was_set(CLOCK_SET_WALL);
986}
987
988static DECLARE_WORK(hrtimer_work, clock_was_set_work);
989
990/*
991 * Called from timekeeping code to reprogram the hrtimer interrupt device
992 * on all cpus and to notify timerfd.
993 */
994void clock_was_set_delayed(void)
995{
996 schedule_work(&hrtimer_work);
997}
998
999/*
1000 * Called during resume either directly from via timekeeping_resume()
1001 * or in the case of s2idle from tick_unfreeze() to ensure that the
1002 * hrtimers are up to date.
1003 */
1004void hrtimers_resume_local(void)
1005{
1006 lockdep_assert_irqs_disabled();
1007 /* Retrigger on the local CPU */
1008 retrigger_next_event(NULL);
1009}
1010
1011/*
1012 * Counterpart to lock_hrtimer_base above:
1013 */
1014static inline
1015void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
1016{
1017 raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
1018}
1019
1020/**
1021 * hrtimer_forward - forward the timer expiry
1022 * @timer: hrtimer to forward
1023 * @now: forward past this time
1024 * @interval: the interval to forward
1025 *
1026 * Forward the timer expiry so it will expire in the future.
1027 * Returns the number of overruns.
1028 *
1029 * Can be safely called from the callback function of @timer. If
1030 * called from other contexts @timer must neither be enqueued nor
1031 * running the callback and the caller needs to take care of
1032 * serialization.
1033 *
1034 * Note: This only updates the timer expiry value and does not requeue
1035 * the timer.
1036 */
1037u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
1038{
1039 u64 orun = 1;
1040 ktime_t delta;
1041
1042 delta = ktime_sub(now, hrtimer_get_expires(timer));
1043
1044 if (delta < 0)
1045 return 0;
1046
1047 if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
1048 return 0;
1049
1050 if (interval < hrtimer_resolution)
1051 interval = hrtimer_resolution;
1052
1053 if (unlikely(delta >= interval)) {
1054 s64 incr = ktime_to_ns(interval);
1055
1056 orun = ktime_divns(delta, incr);
1057 hrtimer_add_expires_ns(timer, incr * orun);
1058 if (hrtimer_get_expires_tv64(timer) > now)
1059 return orun;
1060 /*
1061 * This (and the ktime_add() below) is the
1062 * correction for exact:
1063 */
1064 orun++;
1065 }
1066 hrtimer_add_expires(timer, interval);
1067
1068 return orun;
1069}
1070EXPORT_SYMBOL_GPL(hrtimer_forward);
1071
1072/*
1073 * enqueue_hrtimer - internal function to (re)start a timer
1074 *
1075 * The timer is inserted in expiry order. Insertion into the
1076 * red black tree is O(log(n)). Must hold the base lock.
1077 *
1078 * Returns 1 when the new timer is the leftmost timer in the tree.
1079 */
1080static int enqueue_hrtimer(struct hrtimer *timer,
1081 struct hrtimer_clock_base *base,
1082 enum hrtimer_mode mode)
1083{
1084 debug_activate(timer, mode);
1085
1086 base->cpu_base->active_bases |= 1 << base->index;
1087
1088 /* Pairs with the lockless read in hrtimer_is_queued() */
1089 WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
1090
1091 return timerqueue_add(&base->active, &timer->node);
1092}
1093
1094/*
1095 * __remove_hrtimer - internal function to remove a timer
1096 *
1097 * Caller must hold the base lock.
1098 *
1099 * High resolution timer mode reprograms the clock event device when the
1100 * timer is the one which expires next. The caller can disable this by setting
1101 * reprogram to zero. This is useful, when the context does a reprogramming
1102 * anyway (e.g. timer interrupt)
1103 */
1104static void __remove_hrtimer(struct hrtimer *timer,
1105 struct hrtimer_clock_base *base,
1106 u8 newstate, int reprogram)
1107{
1108 struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1109 u8 state = timer->state;
1110
1111 /* Pairs with the lockless read in hrtimer_is_queued() */
1112 WRITE_ONCE(timer->state, newstate);
1113 if (!(state & HRTIMER_STATE_ENQUEUED))
1114 return;
1115
1116 if (!timerqueue_del(&base->active, &timer->node))
1117 cpu_base->active_bases &= ~(1 << base->index);
1118
1119 /*
1120 * Note: If reprogram is false we do not update
1121 * cpu_base->next_timer. This happens when we remove the first
1122 * timer on a remote cpu. No harm as we never dereference
1123 * cpu_base->next_timer. So the worst thing what can happen is
1124 * an superfluous call to hrtimer_force_reprogram() on the
1125 * remote cpu later on if the same timer gets enqueued again.
1126 */
1127 if (reprogram && timer == cpu_base->next_timer)
1128 hrtimer_force_reprogram(cpu_base, 1);
1129}
1130
1131/*
1132 * remove hrtimer, called with base lock held
1133 */
1134static inline int
1135remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base,
1136 bool restart, bool keep_local)
1137{
1138 u8 state = timer->state;
1139
1140 if (state & HRTIMER_STATE_ENQUEUED) {
1141 bool reprogram;
1142
1143 /*
1144 * Remove the timer and force reprogramming when high
1145 * resolution mode is active and the timer is on the current
1146 * CPU. If we remove a timer on another CPU, reprogramming is
1147 * skipped. The interrupt event on this CPU is fired and
1148 * reprogramming happens in the interrupt handler. This is a
1149 * rare case and less expensive than a smp call.
1150 */
1151 debug_deactivate(timer);
1152 reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1153
1154 /*
1155 * If the timer is not restarted then reprogramming is
1156 * required if the timer is local. If it is local and about
1157 * to be restarted, avoid programming it twice (on removal
1158 * and a moment later when it's requeued).
1159 */
1160 if (!restart)
1161 state = HRTIMER_STATE_INACTIVE;
1162 else
1163 reprogram &= !keep_local;
1164
1165 __remove_hrtimer(timer, base, state, reprogram);
1166 return 1;
1167 }
1168 return 0;
1169}
1170
1171static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
1172 const enum hrtimer_mode mode)
1173{
1174#ifdef CONFIG_TIME_LOW_RES
1175 /*
1176 * CONFIG_TIME_LOW_RES indicates that the system has no way to return
1177 * granular time values. For relative timers we add hrtimer_resolution
1178 * (i.e. one jiffie) to prevent short timeouts.
1179 */
1180 timer->is_rel = mode & HRTIMER_MODE_REL;
1181 if (timer->is_rel)
1182 tim = ktime_add_safe(tim, hrtimer_resolution);
1183#endif
1184 return tim;
1185}
1186
1187static void
1188hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
1189{
1190 ktime_t expires;
1191
1192 /*
1193 * Find the next SOFT expiration.
1194 */
1195 expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
1196
1197 /*
1198 * reprogramming needs to be triggered, even if the next soft
1199 * hrtimer expires at the same time than the next hard
1200 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
1201 */
1202 if (expires == KTIME_MAX)
1203 return;
1204
1205 /*
1206 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
1207 * cpu_base->*expires_next is only set by hrtimer_reprogram()
1208 */
1209 hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
1210}
1211
1212static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1213 u64 delta_ns, const enum hrtimer_mode mode,
1214 struct hrtimer_clock_base *base)
1215{
1216 struct hrtimer_clock_base *new_base;
1217 bool force_local, first;
1218
1219 /*
1220 * If the timer is on the local cpu base and is the first expiring
1221 * timer then this might end up reprogramming the hardware twice
1222 * (on removal and on enqueue). To avoid that by prevent the
1223 * reprogram on removal, keep the timer local to the current CPU
1224 * and enforce reprogramming after it is queued no matter whether
1225 * it is the new first expiring timer again or not.
1226 */
1227 force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1228 force_local &= base->cpu_base->next_timer == timer;
1229
1230 /*
1231 * Remove an active timer from the queue. In case it is not queued
1232 * on the current CPU, make sure that remove_hrtimer() updates the
1233 * remote data correctly.
1234 *
1235 * If it's on the current CPU and the first expiring timer, then
1236 * skip reprogramming, keep the timer local and enforce
1237 * reprogramming later if it was the first expiring timer. This
1238 * avoids programming the underlying clock event twice (once at
1239 * removal and once after enqueue).
1240 */
1241 remove_hrtimer(timer, base, true, force_local);
1242
1243 if (mode & HRTIMER_MODE_REL)
1244 tim = ktime_add_safe(tim, base->get_time());
1245
1246 tim = hrtimer_update_lowres(timer, tim, mode);
1247
1248 hrtimer_set_expires_range_ns(timer, tim, delta_ns);
1249
1250 /* Switch the timer base, if necessary: */
1251 if (!force_local) {
1252 new_base = switch_hrtimer_base(timer, base,
1253 mode & HRTIMER_MODE_PINNED);
1254 } else {
1255 new_base = base;
1256 }
1257
1258 first = enqueue_hrtimer(timer, new_base, mode);
1259 if (!force_local)
1260 return first;
1261
1262 /*
1263 * Timer was forced to stay on the current CPU to avoid
1264 * reprogramming on removal and enqueue. Force reprogram the
1265 * hardware by evaluating the new first expiring timer.
1266 */
1267 hrtimer_force_reprogram(new_base->cpu_base, 1);
1268 return 0;
1269}
1270
1271/**
1272 * hrtimer_start_range_ns - (re)start an hrtimer
1273 * @timer: the timer to be added
1274 * @tim: expiry time
1275 * @delta_ns: "slack" range for the timer
1276 * @mode: timer mode: absolute (HRTIMER_MODE_ABS) or
1277 * relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
1278 * softirq based mode is considered for debug purpose only!
1279 */
1280void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1281 u64 delta_ns, const enum hrtimer_mode mode)
1282{
1283 struct hrtimer_clock_base *base;
1284 unsigned long flags;
1285
1286 /*
1287 * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
1288 * match on CONFIG_PREEMPT_RT = n. With PREEMPT_RT check the hard
1289 * expiry mode because unmarked timers are moved to softirq expiry.
1290 */
1291 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
1292 WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
1293 else
1294 WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard);
1295
1296 base = lock_hrtimer_base(timer, &flags);
1297
1298 if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
1299 hrtimer_reprogram(timer, true);
1300
1301 unlock_hrtimer_base(timer, &flags);
1302}
1303EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1304
1305/**
1306 * hrtimer_try_to_cancel - try to deactivate a timer
1307 * @timer: hrtimer to stop
1308 *
1309 * Returns:
1310 *
1311 * * 0 when the timer was not active
1312 * * 1 when the timer was active
1313 * * -1 when the timer is currently executing the callback function and
1314 * cannot be stopped
1315 */
1316int hrtimer_try_to_cancel(struct hrtimer *timer)
1317{
1318 struct hrtimer_clock_base *base;
1319 unsigned long flags;
1320 int ret = -1;
1321
1322 /*
1323 * Check lockless first. If the timer is not active (neither
1324 * enqueued nor running the callback, nothing to do here. The
1325 * base lock does not serialize against a concurrent enqueue,
1326 * so we can avoid taking it.
1327 */
1328 if (!hrtimer_active(timer))
1329 return 0;
1330
1331 base = lock_hrtimer_base(timer, &flags);
1332
1333 if (!hrtimer_callback_running(timer))
1334 ret = remove_hrtimer(timer, base, false, false);
1335
1336 unlock_hrtimer_base(timer, &flags);
1337
1338 return ret;
1339
1340}
1341EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1342
1343#ifdef CONFIG_PREEMPT_RT
1344static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
1345{
1346 spin_lock_init(&base->softirq_expiry_lock);
1347}
1348
1349static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
1350{
1351 spin_lock(&base->softirq_expiry_lock);
1352}
1353
1354static void hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base)
1355{
1356 spin_unlock(&base->softirq_expiry_lock);
1357}
1358
1359/*
1360 * The counterpart to hrtimer_cancel_wait_running().
1361 *
1362 * If there is a waiter for cpu_base->expiry_lock, then it was waiting for
1363 * the timer callback to finish. Drop expiry_lock and reacquire it. That
1364 * allows the waiter to acquire the lock and make progress.
1365 */
1366static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base,
1367 unsigned long flags)
1368{
1369 if (atomic_read(&cpu_base->timer_waiters)) {
1370 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1371 spin_unlock(&cpu_base->softirq_expiry_lock);
1372 spin_lock(&cpu_base->softirq_expiry_lock);
1373 raw_spin_lock_irq(&cpu_base->lock);
1374 }
1375}
1376
1377/*
1378 * This function is called on PREEMPT_RT kernels when the fast path
1379 * deletion of a timer failed because the timer callback function was
1380 * running.
1381 *
1382 * This prevents priority inversion: if the soft irq thread is preempted
1383 * in the middle of a timer callback, then calling del_timer_sync() can
1384 * lead to two issues:
1385 *
1386 * - If the caller is on a remote CPU then it has to spin wait for the timer
1387 * handler to complete. This can result in unbound priority inversion.
1388 *
1389 * - If the caller originates from the task which preempted the timer
1390 * handler on the same CPU, then spin waiting for the timer handler to
1391 * complete is never going to end.
1392 */
1393void hrtimer_cancel_wait_running(const struct hrtimer *timer)
1394{
1395 /* Lockless read. Prevent the compiler from reloading it below */
1396 struct hrtimer_clock_base *base = READ_ONCE(timer->base);
1397
1398 /*
1399 * Just relax if the timer expires in hard interrupt context or if
1400 * it is currently on the migration base.
1401 */
1402 if (!timer->is_soft || is_migration_base(base)) {
1403 cpu_relax();
1404 return;
1405 }
1406
1407 /*
1408 * Mark the base as contended and grab the expiry lock, which is
1409 * held by the softirq across the timer callback. Drop the lock
1410 * immediately so the softirq can expire the next timer. In theory
1411 * the timer could already be running again, but that's more than
1412 * unlikely and just causes another wait loop.
1413 */
1414 atomic_inc(&base->cpu_base->timer_waiters);
1415 spin_lock_bh(&base->cpu_base->softirq_expiry_lock);
1416 atomic_dec(&base->cpu_base->timer_waiters);
1417 spin_unlock_bh(&base->cpu_base->softirq_expiry_lock);
1418}
1419#else
1420static inline void
1421hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
1422static inline void
1423hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
1424static inline void
1425hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
1426static inline void hrtimer_sync_wait_running(struct hrtimer_cpu_base *base,
1427 unsigned long flags) { }
1428#endif
1429
1430/**
1431 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1432 * @timer: the timer to be cancelled
1433 *
1434 * Returns:
1435 * 0 when the timer was not active
1436 * 1 when the timer was active
1437 */
1438int hrtimer_cancel(struct hrtimer *timer)
1439{
1440 int ret;
1441
1442 do {
1443 ret = hrtimer_try_to_cancel(timer);
1444
1445 if (ret < 0)
1446 hrtimer_cancel_wait_running(timer);
1447 } while (ret < 0);
1448 return ret;
1449}
1450EXPORT_SYMBOL_GPL(hrtimer_cancel);
1451
1452/**
1453 * __hrtimer_get_remaining - get remaining time for the timer
1454 * @timer: the timer to read
1455 * @adjust: adjust relative timers when CONFIG_TIME_LOW_RES=y
1456 */
1457ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
1458{
1459 unsigned long flags;
1460 ktime_t rem;
1461
1462 lock_hrtimer_base(timer, &flags);
1463 if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
1464 rem = hrtimer_expires_remaining_adjusted(timer);
1465 else
1466 rem = hrtimer_expires_remaining(timer);
1467 unlock_hrtimer_base(timer, &flags);
1468
1469 return rem;
1470}
1471EXPORT_SYMBOL_GPL(__hrtimer_get_remaining);
1472
1473#ifdef CONFIG_NO_HZ_COMMON
1474/**
1475 * hrtimer_get_next_event - get the time until next expiry event
1476 *
1477 * Returns the next expiry time or KTIME_MAX if no timer is pending.
1478 */
1479u64 hrtimer_get_next_event(void)
1480{
1481 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1482 u64 expires = KTIME_MAX;
1483 unsigned long flags;
1484
1485 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1486
1487 if (!__hrtimer_hres_active(cpu_base))
1488 expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
1489
1490 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1491
1492 return expires;
1493}
1494
1495/**
1496 * hrtimer_next_event_without - time until next expiry event w/o one timer
1497 * @exclude: timer to exclude
1498 *
1499 * Returns the next expiry time over all timers except for the @exclude one or
1500 * KTIME_MAX if none of them is pending.
1501 */
1502u64 hrtimer_next_event_without(const struct hrtimer *exclude)
1503{
1504 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1505 u64 expires = KTIME_MAX;
1506 unsigned long flags;
1507
1508 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1509
1510 if (__hrtimer_hres_active(cpu_base)) {
1511 unsigned int active;
1512
1513 if (!cpu_base->softirq_activated) {
1514 active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
1515 expires = __hrtimer_next_event_base(cpu_base, exclude,
1516 active, KTIME_MAX);
1517 }
1518 active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
1519 expires = __hrtimer_next_event_base(cpu_base, exclude, active,
1520 expires);
1521 }
1522
1523 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1524
1525 return expires;
1526}
1527#endif
1528
1529static inline int hrtimer_clockid_to_base(clockid_t clock_id)
1530{
1531 if (likely(clock_id < MAX_CLOCKS)) {
1532 int base = hrtimer_clock_to_base_table[clock_id];
1533
1534 if (likely(base != HRTIMER_MAX_CLOCK_BASES))
1535 return base;
1536 }
1537 WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
1538 return HRTIMER_BASE_MONOTONIC;
1539}
1540
1541static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1542 enum hrtimer_mode mode)
1543{
1544 bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
1545 struct hrtimer_cpu_base *cpu_base;
1546 int base;
1547
1548 /*
1549 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1550 * marked for hard interrupt expiry mode are moved into soft
1551 * interrupt context for latency reasons and because the callbacks
1552 * can invoke functions which might sleep on RT, e.g. spin_lock().
1553 */
1554 if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD))
1555 softtimer = true;
1556
1557 memset(timer, 0, sizeof(struct hrtimer));
1558
1559 cpu_base = raw_cpu_ptr(&hrtimer_bases);
1560
1561 /*
1562 * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
1563 * clock modifications, so they needs to become CLOCK_MONOTONIC to
1564 * ensure POSIX compliance.
1565 */
1566 if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
1567 clock_id = CLOCK_MONOTONIC;
1568
1569 base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
1570 base += hrtimer_clockid_to_base(clock_id);
1571 timer->is_soft = softtimer;
1572 timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
1573 timer->base = &cpu_base->clock_base[base];
1574 timerqueue_init(&timer->node);
1575}
1576
1577/**
1578 * hrtimer_init - initialize a timer to the given clock
1579 * @timer: the timer to be initialized
1580 * @clock_id: the clock to be used
1581 * @mode: The modes which are relevant for initialization:
1582 * HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
1583 * HRTIMER_MODE_REL_SOFT
1584 *
1585 * The PINNED variants of the above can be handed in,
1586 * but the PINNED bit is ignored as pinning happens
1587 * when the hrtimer is started
1588 */
1589void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1590 enum hrtimer_mode mode)
1591{
1592 debug_init(timer, clock_id, mode);
1593 __hrtimer_init(timer, clock_id, mode);
1594}
1595EXPORT_SYMBOL_GPL(hrtimer_init);
1596
1597/*
1598 * A timer is active, when it is enqueued into the rbtree or the
1599 * callback function is running or it's in the state of being migrated
1600 * to another cpu.
1601 *
1602 * It is important for this function to not return a false negative.
1603 */
1604bool hrtimer_active(const struct hrtimer *timer)
1605{
1606 struct hrtimer_clock_base *base;
1607 unsigned int seq;
1608
1609 do {
1610 base = READ_ONCE(timer->base);
1611 seq = raw_read_seqcount_begin(&base->seq);
1612
1613 if (timer->state != HRTIMER_STATE_INACTIVE ||
1614 base->running == timer)
1615 return true;
1616
1617 } while (read_seqcount_retry(&base->seq, seq) ||
1618 base != READ_ONCE(timer->base));
1619
1620 return false;
1621}
1622EXPORT_SYMBOL_GPL(hrtimer_active);
1623
1624/*
1625 * The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
1626 * distinct sections:
1627 *
1628 * - queued: the timer is queued
1629 * - callback: the timer is being ran
1630 * - post: the timer is inactive or (re)queued
1631 *
1632 * On the read side we ensure we observe timer->state and cpu_base->running
1633 * from the same section, if anything changed while we looked at it, we retry.
1634 * This includes timer->base changing because sequence numbers alone are
1635 * insufficient for that.
1636 *
1637 * The sequence numbers are required because otherwise we could still observe
1638 * a false negative if the read side got smeared over multiple consecutive
1639 * __run_hrtimer() invocations.
1640 */
1641
1642static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
1643 struct hrtimer_clock_base *base,
1644 struct hrtimer *timer, ktime_t *now,
1645 unsigned long flags) __must_hold(&cpu_base->lock)
1646{
1647 enum hrtimer_restart (*fn)(struct hrtimer *);
1648 bool expires_in_hardirq;
1649 int restart;
1650
1651 lockdep_assert_held(&cpu_base->lock);
1652
1653 debug_deactivate(timer);
1654 base->running = timer;
1655
1656 /*
1657 * Separate the ->running assignment from the ->state assignment.
1658 *
1659 * As with a regular write barrier, this ensures the read side in
1660 * hrtimer_active() cannot observe base->running == NULL &&
1661 * timer->state == INACTIVE.
1662 */
1663 raw_write_seqcount_barrier(&base->seq);
1664
1665 __remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
1666 fn = timer->function;
1667
1668 /*
1669 * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
1670 * timer is restarted with a period then it becomes an absolute
1671 * timer. If its not restarted it does not matter.
1672 */
1673 if (IS_ENABLED(CONFIG_TIME_LOW_RES))
1674 timer->is_rel = false;
1675
1676 /*
1677 * The timer is marked as running in the CPU base, so it is
1678 * protected against migration to a different CPU even if the lock
1679 * is dropped.
1680 */
1681 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1682 trace_hrtimer_expire_entry(timer, now);
1683 expires_in_hardirq = lockdep_hrtimer_enter(timer);
1684
1685 restart = fn(timer);
1686
1687 lockdep_hrtimer_exit(expires_in_hardirq);
1688 trace_hrtimer_expire_exit(timer);
1689 raw_spin_lock_irq(&cpu_base->lock);
1690
1691 /*
1692 * Note: We clear the running state after enqueue_hrtimer and
1693 * we do not reprogram the event hardware. Happens either in
1694 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1695 *
1696 * Note: Because we dropped the cpu_base->lock above,
1697 * hrtimer_start_range_ns() can have popped in and enqueued the timer
1698 * for us already.
1699 */
1700 if (restart != HRTIMER_NORESTART &&
1701 !(timer->state & HRTIMER_STATE_ENQUEUED))
1702 enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
1703
1704 /*
1705 * Separate the ->running assignment from the ->state assignment.
1706 *
1707 * As with a regular write barrier, this ensures the read side in
1708 * hrtimer_active() cannot observe base->running.timer == NULL &&
1709 * timer->state == INACTIVE.
1710 */
1711 raw_write_seqcount_barrier(&base->seq);
1712
1713 WARN_ON_ONCE(base->running != timer);
1714 base->running = NULL;
1715}
1716
1717static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
1718 unsigned long flags, unsigned int active_mask)
1719{
1720 struct hrtimer_clock_base *base;
1721 unsigned int active = cpu_base->active_bases & active_mask;
1722
1723 for_each_active_base(base, cpu_base, active) {
1724 struct timerqueue_node *node;
1725 ktime_t basenow;
1726
1727 basenow = ktime_add(now, base->offset);
1728
1729 while ((node = timerqueue_getnext(&base->active))) {
1730 struct hrtimer *timer;
1731
1732 timer = container_of(node, struct hrtimer, node);
1733
1734 /*
1735 * The immediate goal for using the softexpires is
1736 * minimizing wakeups, not running timers at the
1737 * earliest interrupt after their soft expiration.
1738 * This allows us to avoid using a Priority Search
1739 * Tree, which can answer a stabbing query for
1740 * overlapping intervals and instead use the simple
1741 * BST we already have.
1742 * We don't add extra wakeups by delaying timers that
1743 * are right-of a not yet expired timer, because that
1744 * timer will have to trigger a wakeup anyway.
1745 */
1746 if (basenow < hrtimer_get_softexpires_tv64(timer))
1747 break;
1748
1749 __run_hrtimer(cpu_base, base, timer, &basenow, flags);
1750 if (active_mask == HRTIMER_ACTIVE_SOFT)
1751 hrtimer_sync_wait_running(cpu_base, flags);
1752 }
1753 }
1754}
1755
1756static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
1757{
1758 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1759 unsigned long flags;
1760 ktime_t now;
1761
1762 hrtimer_cpu_base_lock_expiry(cpu_base);
1763 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1764
1765 now = hrtimer_update_base(cpu_base);
1766 __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
1767
1768 cpu_base->softirq_activated = 0;
1769 hrtimer_update_softirq_timer(cpu_base, true);
1770
1771 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1772 hrtimer_cpu_base_unlock_expiry(cpu_base);
1773}
1774
1775#ifdef CONFIG_HIGH_RES_TIMERS
1776
1777/*
1778 * High resolution timer interrupt
1779 * Called with interrupts disabled
1780 */
1781void hrtimer_interrupt(struct clock_event_device *dev)
1782{
1783 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1784 ktime_t expires_next, now, entry_time, delta;
1785 unsigned long flags;
1786 int retries = 0;
1787
1788 BUG_ON(!cpu_base->hres_active);
1789 cpu_base->nr_events++;
1790 dev->next_event = KTIME_MAX;
1791
1792 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1793 entry_time = now = hrtimer_update_base(cpu_base);
1794retry:
1795 cpu_base->in_hrtirq = 1;
1796 /*
1797 * We set expires_next to KTIME_MAX here with cpu_base->lock
1798 * held to prevent that a timer is enqueued in our queue via
1799 * the migration code. This does not affect enqueueing of
1800 * timers which run their callback and need to be requeued on
1801 * this CPU.
1802 */
1803 cpu_base->expires_next = KTIME_MAX;
1804
1805 if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1806 cpu_base->softirq_expires_next = KTIME_MAX;
1807 cpu_base->softirq_activated = 1;
1808 raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1809 }
1810
1811 __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1812
1813 /* Reevaluate the clock bases for the [soft] next expiry */
1814 expires_next = hrtimer_update_next_event(cpu_base);
1815 /*
1816 * Store the new expiry value so the migration code can verify
1817 * against it.
1818 */
1819 cpu_base->expires_next = expires_next;
1820 cpu_base->in_hrtirq = 0;
1821 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1822
1823 /* Reprogramming necessary ? */
1824 if (!tick_program_event(expires_next, 0)) {
1825 cpu_base->hang_detected = 0;
1826 return;
1827 }
1828
1829 /*
1830 * The next timer was already expired due to:
1831 * - tracing
1832 * - long lasting callbacks
1833 * - being scheduled away when running in a VM
1834 *
1835 * We need to prevent that we loop forever in the hrtimer
1836 * interrupt routine. We give it 3 attempts to avoid
1837 * overreacting on some spurious event.
1838 *
1839 * Acquire base lock for updating the offsets and retrieving
1840 * the current time.
1841 */
1842 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1843 now = hrtimer_update_base(cpu_base);
1844 cpu_base->nr_retries++;
1845 if (++retries < 3)
1846 goto retry;
1847 /*
1848 * Give the system a chance to do something else than looping
1849 * here. We stored the entry time, so we know exactly how long
1850 * we spent here. We schedule the next event this amount of
1851 * time away.
1852 */
1853 cpu_base->nr_hangs++;
1854 cpu_base->hang_detected = 1;
1855 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1856
1857 delta = ktime_sub(now, entry_time);
1858 if ((unsigned int)delta > cpu_base->max_hang_time)
1859 cpu_base->max_hang_time = (unsigned int) delta;
1860 /*
1861 * Limit it to a sensible value as we enforce a longer
1862 * delay. Give the CPU at least 100ms to catch up.
1863 */
1864 if (delta > 100 * NSEC_PER_MSEC)
1865 expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1866 else
1867 expires_next = ktime_add(now, delta);
1868 tick_program_event(expires_next, 1);
1869 pr_warn_once("hrtimer: interrupt took %llu ns\n", ktime_to_ns(delta));
1870}
1871
1872/* called with interrupts disabled */
1873static inline void __hrtimer_peek_ahead_timers(void)
1874{
1875 struct tick_device *td;
1876
1877 if (!hrtimer_hres_active())
1878 return;
1879
1880 td = this_cpu_ptr(&tick_cpu_device);
1881 if (td && td->evtdev)
1882 hrtimer_interrupt(td->evtdev);
1883}
1884
1885#else /* CONFIG_HIGH_RES_TIMERS */
1886
1887static inline void __hrtimer_peek_ahead_timers(void) { }
1888
1889#endif /* !CONFIG_HIGH_RES_TIMERS */
1890
1891/*
1892 * Called from run_local_timers in hardirq context every jiffy
1893 */
1894void hrtimer_run_queues(void)
1895{
1896 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1897 unsigned long flags;
1898 ktime_t now;
1899
1900 if (__hrtimer_hres_active(cpu_base))
1901 return;
1902
1903 /*
1904 * This _is_ ugly: We have to check periodically, whether we
1905 * can switch to highres and / or nohz mode. The clocksource
1906 * switch happens with xtime_lock held. Notification from
1907 * there only sets the check bit in the tick_oneshot code,
1908 * otherwise we might deadlock vs. xtime_lock.
1909 */
1910 if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
1911 hrtimer_switch_to_hres();
1912 return;
1913 }
1914
1915 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1916 now = hrtimer_update_base(cpu_base);
1917
1918 if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1919 cpu_base->softirq_expires_next = KTIME_MAX;
1920 cpu_base->softirq_activated = 1;
1921 raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1922 }
1923
1924 __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1925 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1926}
1927
1928/*
1929 * Sleep related functions:
1930 */
1931static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1932{
1933 struct hrtimer_sleeper *t =
1934 container_of(timer, struct hrtimer_sleeper, timer);
1935 struct task_struct *task = t->task;
1936
1937 t->task = NULL;
1938 if (task)
1939 wake_up_process(task);
1940
1941 return HRTIMER_NORESTART;
1942}
1943
1944/**
1945 * hrtimer_sleeper_start_expires - Start a hrtimer sleeper timer
1946 * @sl: sleeper to be started
1947 * @mode: timer mode abs/rel
1948 *
1949 * Wrapper around hrtimer_start_expires() for hrtimer_sleeper based timers
1950 * to allow PREEMPT_RT to tweak the delivery mode (soft/hardirq context)
1951 */
1952void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
1953 enum hrtimer_mode mode)
1954{
1955 /*
1956 * Make the enqueue delivery mode check work on RT. If the sleeper
1957 * was initialized for hard interrupt delivery, force the mode bit.
1958 * This is a special case for hrtimer_sleepers because
1959 * hrtimer_init_sleeper() determines the delivery mode on RT so the
1960 * fiddling with this decision is avoided at the call sites.
1961 */
1962 if (IS_ENABLED(CONFIG_PREEMPT_RT) && sl->timer.is_hard)
1963 mode |= HRTIMER_MODE_HARD;
1964
1965 hrtimer_start_expires(&sl->timer, mode);
1966}
1967EXPORT_SYMBOL_GPL(hrtimer_sleeper_start_expires);
1968
1969static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
1970 clockid_t clock_id, enum hrtimer_mode mode)
1971{
1972 /*
1973 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1974 * marked for hard interrupt expiry mode are moved into soft
1975 * interrupt context either for latency reasons or because the
1976 * hrtimer callback takes regular spinlocks or invokes other
1977 * functions which are not suitable for hard interrupt context on
1978 * PREEMPT_RT.
1979 *
1980 * The hrtimer_sleeper callback is RT compatible in hard interrupt
1981 * context, but there is a latency concern: Untrusted userspace can
1982 * spawn many threads which arm timers for the same expiry time on
1983 * the same CPU. That causes a latency spike due to the wakeup of
1984 * a gazillion threads.
1985 *
1986 * OTOH, privileged real-time user space applications rely on the
1987 * low latency of hard interrupt wakeups. If the current task is in
1988 * a real-time scheduling class, mark the mode for hard interrupt
1989 * expiry.
1990 */
1991 if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
1992 if (task_is_realtime(current) && !(mode & HRTIMER_MODE_SOFT))
1993 mode |= HRTIMER_MODE_HARD;
1994 }
1995
1996 __hrtimer_init(&sl->timer, clock_id, mode);
1997 sl->timer.function = hrtimer_wakeup;
1998 sl->task = current;
1999}
2000
2001/**
2002 * hrtimer_init_sleeper - initialize sleeper to the given clock
2003 * @sl: sleeper to be initialized
2004 * @clock_id: the clock to be used
2005 * @mode: timer mode abs/rel
2006 */
2007void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
2008 enum hrtimer_mode mode)
2009{
2010 debug_init(&sl->timer, clock_id, mode);
2011 __hrtimer_init_sleeper(sl, clock_id, mode);
2012
2013}
2014EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
2015
2016int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
2017{
2018 switch(restart->nanosleep.type) {
2019#ifdef CONFIG_COMPAT_32BIT_TIME
2020 case TT_COMPAT:
2021 if (put_old_timespec32(ts, restart->nanosleep.compat_rmtp))
2022 return -EFAULT;
2023 break;
2024#endif
2025 case TT_NATIVE:
2026 if (put_timespec64(ts, restart->nanosleep.rmtp))
2027 return -EFAULT;
2028 break;
2029 default:
2030 BUG();
2031 }
2032 return -ERESTART_RESTARTBLOCK;
2033}
2034
2035static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
2036{
2037 struct restart_block *restart;
2038
2039 do {
2040 set_current_state(TASK_INTERRUPTIBLE);
2041 hrtimer_sleeper_start_expires(t, mode);
2042
2043 if (likely(t->task))
2044 freezable_schedule();
2045
2046 hrtimer_cancel(&t->timer);
2047 mode = HRTIMER_MODE_ABS;
2048
2049 } while (t->task && !signal_pending(current));
2050
2051 __set_current_state(TASK_RUNNING);
2052
2053 if (!t->task)
2054 return 0;
2055
2056 restart = &current->restart_block;
2057 if (restart->nanosleep.type != TT_NONE) {
2058 ktime_t rem = hrtimer_expires_remaining(&t->timer);
2059 struct timespec64 rmt;
2060
2061 if (rem <= 0)
2062 return 0;
2063 rmt = ktime_to_timespec64(rem);
2064
2065 return nanosleep_copyout(restart, &rmt);
2066 }
2067 return -ERESTART_RESTARTBLOCK;
2068}
2069
2070static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
2071{
2072 struct hrtimer_sleeper t;
2073 int ret;
2074
2075 hrtimer_init_sleeper_on_stack(&t, restart->nanosleep.clockid,
2076 HRTIMER_MODE_ABS);
2077 hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
2078 ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
2079 destroy_hrtimer_on_stack(&t.timer);
2080 return ret;
2081}
2082
2083long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
2084 const clockid_t clockid)
2085{
2086 struct restart_block *restart;
2087 struct hrtimer_sleeper t;
2088 int ret = 0;
2089 u64 slack;
2090
2091 slack = current->timer_slack_ns;
2092 if (dl_task(current) || rt_task(current))
2093 slack = 0;
2094
2095 hrtimer_init_sleeper_on_stack(&t, clockid, mode);
2096 hrtimer_set_expires_range_ns(&t.timer, rqtp, slack);
2097 ret = do_nanosleep(&t, mode);
2098 if (ret != -ERESTART_RESTARTBLOCK)
2099 goto out;
2100
2101 /* Absolute timers do not update the rmtp value and restart: */
2102 if (mode == HRTIMER_MODE_ABS) {
2103 ret = -ERESTARTNOHAND;
2104 goto out;
2105 }
2106
2107 restart = &current->restart_block;
2108 restart->nanosleep.clockid = t.timer.base->clockid;
2109 restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
2110 set_restart_fn(restart, hrtimer_nanosleep_restart);
2111out:
2112 destroy_hrtimer_on_stack(&t.timer);
2113 return ret;
2114}
2115
2116#ifdef CONFIG_64BIT
2117
2118SYSCALL_DEFINE2(nanosleep, struct __kernel_timespec __user *, rqtp,
2119 struct __kernel_timespec __user *, rmtp)
2120{
2121 struct timespec64 tu;
2122
2123 if (get_timespec64(&tu, rqtp))
2124 return -EFAULT;
2125
2126 if (!timespec64_valid(&tu))
2127 return -EINVAL;
2128
2129 current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
2130 current->restart_block.nanosleep.rmtp = rmtp;
2131 return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2132 CLOCK_MONOTONIC);
2133}
2134
2135#endif
2136
2137#ifdef CONFIG_COMPAT_32BIT_TIME
2138
2139SYSCALL_DEFINE2(nanosleep_time32, struct old_timespec32 __user *, rqtp,
2140 struct old_timespec32 __user *, rmtp)
2141{
2142 struct timespec64 tu;
2143
2144 if (get_old_timespec32(&tu, rqtp))
2145 return -EFAULT;
2146
2147 if (!timespec64_valid(&tu))
2148 return -EINVAL;
2149
2150 current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
2151 current->restart_block.nanosleep.compat_rmtp = rmtp;
2152 return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2153 CLOCK_MONOTONIC);
2154}
2155#endif
2156
2157/*
2158 * Functions related to boot-time initialization:
2159 */
2160int hrtimers_prepare_cpu(unsigned int cpu)
2161{
2162 struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
2163 int i;
2164
2165 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2166 struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i];
2167
2168 clock_b->cpu_base = cpu_base;
2169 seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock);
2170 timerqueue_init_head(&clock_b->active);
2171 }
2172
2173 cpu_base->cpu = cpu;
2174 cpu_base->active_bases = 0;
2175 cpu_base->hres_active = 0;
2176 cpu_base->hang_detected = 0;
2177 cpu_base->next_timer = NULL;
2178 cpu_base->softirq_next_timer = NULL;
2179 cpu_base->expires_next = KTIME_MAX;
2180 cpu_base->softirq_expires_next = KTIME_MAX;
2181 hrtimer_cpu_base_init_expiry_lock(cpu_base);
2182 return 0;
2183}
2184
2185#ifdef CONFIG_HOTPLUG_CPU
2186
2187static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
2188 struct hrtimer_clock_base *new_base)
2189{
2190 struct hrtimer *timer;
2191 struct timerqueue_node *node;
2192
2193 while ((node = timerqueue_getnext(&old_base->active))) {
2194 timer = container_of(node, struct hrtimer, node);
2195 BUG_ON(hrtimer_callback_running(timer));
2196 debug_deactivate(timer);
2197
2198 /*
2199 * Mark it as ENQUEUED not INACTIVE otherwise the
2200 * timer could be seen as !active and just vanish away
2201 * under us on another CPU
2202 */
2203 __remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
2204 timer->base = new_base;
2205 /*
2206 * Enqueue the timers on the new cpu. This does not
2207 * reprogram the event device in case the timer
2208 * expires before the earliest on this CPU, but we run
2209 * hrtimer_interrupt after we migrated everything to
2210 * sort out already expired timers and reprogram the
2211 * event device.
2212 */
2213 enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
2214 }
2215}
2216
2217int hrtimers_dead_cpu(unsigned int scpu)
2218{
2219 struct hrtimer_cpu_base *old_base, *new_base;
2220 int i;
2221
2222 BUG_ON(cpu_online(scpu));
2223 tick_cancel_sched_timer(scpu);
2224
2225 /*
2226 * this BH disable ensures that raise_softirq_irqoff() does
2227 * not wakeup ksoftirqd (and acquire the pi-lock) while
2228 * holding the cpu_base lock
2229 */
2230 local_bh_disable();
2231 local_irq_disable();
2232 old_base = &per_cpu(hrtimer_bases, scpu);
2233 new_base = this_cpu_ptr(&hrtimer_bases);
2234 /*
2235 * The caller is globally serialized and nobody else
2236 * takes two locks at once, deadlock is not possible.
2237 */
2238 raw_spin_lock(&new_base->lock);
2239 raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
2240
2241 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2242 migrate_hrtimer_list(&old_base->clock_base[i],
2243 &new_base->clock_base[i]);
2244 }
2245
2246 /*
2247 * The migration might have changed the first expiring softirq
2248 * timer on this CPU. Update it.
2249 */
2250 hrtimer_update_softirq_timer(new_base, false);
2251
2252 raw_spin_unlock(&old_base->lock);
2253 raw_spin_unlock(&new_base->lock);
2254
2255 /* Check, if we got expired work to do */
2256 __hrtimer_peek_ahead_timers();
2257 local_irq_enable();
2258 local_bh_enable();
2259 return 0;
2260}
2261
2262#endif /* CONFIG_HOTPLUG_CPU */
2263
2264void __init hrtimers_init(void)
2265{
2266 hrtimers_prepare_cpu(smp_processor_id());
2267 open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
2268}
2269
2270/**
2271 * schedule_hrtimeout_range_clock - sleep until timeout
2272 * @expires: timeout value (ktime_t)
2273 * @delta: slack in expires timeout (ktime_t)
2274 * @mode: timer mode
2275 * @clock_id: timer clock to be used
2276 */
2277int __sched
2278schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
2279 const enum hrtimer_mode mode, clockid_t clock_id)
2280{
2281 struct hrtimer_sleeper t;
2282
2283 /*
2284 * Optimize when a zero timeout value is given. It does not
2285 * matter whether this is an absolute or a relative time.
2286 */
2287 if (expires && *expires == 0) {
2288 __set_current_state(TASK_RUNNING);
2289 return 0;
2290 }
2291
2292 /*
2293 * A NULL parameter means "infinite"
2294 */
2295 if (!expires) {
2296 schedule();
2297 return -EINTR;
2298 }
2299
2300 hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
2301 hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
2302 hrtimer_sleeper_start_expires(&t, mode);
2303
2304 if (likely(t.task))
2305 schedule();
2306
2307 hrtimer_cancel(&t.timer);
2308 destroy_hrtimer_on_stack(&t.timer);
2309
2310 __set_current_state(TASK_RUNNING);
2311
2312 return !t.task ? 0 : -EINTR;
2313}
2314
2315/**
2316 * schedule_hrtimeout_range - sleep until timeout
2317 * @expires: timeout value (ktime_t)
2318 * @delta: slack in expires timeout (ktime_t)
2319 * @mode: timer mode
2320 *
2321 * Make the current task sleep until the given expiry time has
2322 * elapsed. The routine will return immediately unless
2323 * the current task state has been set (see set_current_state()).
2324 *
2325 * The @delta argument gives the kernel the freedom to schedule the
2326 * actual wakeup to a time that is both power and performance friendly.
2327 * The kernel give the normal best effort behavior for "@expires+@delta",
2328 * but may decide to fire the timer earlier, but no earlier than @expires.
2329 *
2330 * You can set the task state as follows -
2331 *
2332 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2333 * pass before the routine returns unless the current task is explicitly
2334 * woken up, (e.g. by wake_up_process()).
2335 *
2336 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2337 * delivered to the current task or the current task is explicitly woken
2338 * up.
2339 *
2340 * The current task state is guaranteed to be TASK_RUNNING when this
2341 * routine returns.
2342 *
2343 * Returns 0 when the timer has expired. If the task was woken before the
2344 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2345 * by an explicit wakeup, it returns -EINTR.
2346 */
2347int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
2348 const enum hrtimer_mode mode)
2349{
2350 return schedule_hrtimeout_range_clock(expires, delta, mode,
2351 CLOCK_MONOTONIC);
2352}
2353EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
2354
2355/**
2356 * schedule_hrtimeout - sleep until timeout
2357 * @expires: timeout value (ktime_t)
2358 * @mode: timer mode
2359 *
2360 * Make the current task sleep until the given expiry time has
2361 * elapsed. The routine will return immediately unless
2362 * the current task state has been set (see set_current_state()).
2363 *
2364 * You can set the task state as follows -
2365 *
2366 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2367 * pass before the routine returns unless the current task is explicitly
2368 * woken up, (e.g. by wake_up_process()).
2369 *
2370 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2371 * delivered to the current task or the current task is explicitly woken
2372 * up.
2373 *
2374 * The current task state is guaranteed to be TASK_RUNNING when this
2375 * routine returns.
2376 *
2377 * Returns 0 when the timer has expired. If the task was woken before the
2378 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2379 * by an explicit wakeup, it returns -EINTR.
2380 */
2381int __sched schedule_hrtimeout(ktime_t *expires,
2382 const enum hrtimer_mode mode)
2383{
2384 return schedule_hrtimeout_range(expires, 0, mode);
2385}
2386EXPORT_SYMBOL_GPL(schedule_hrtimeout);