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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
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/sched/isolation.h>
42#include <linux/timer.h>
43#include <linux/freezer.h>
44#include <linux/compat.h>
45
46#include <linux/uaccess.h>
47
48#include <trace/events/timer.h>
49
50#include "tick-internal.h"
51
52/*
53 * Masks for selecting the soft and hard context timers from
54 * cpu_base->active
55 */
56#define MASK_SHIFT (HRTIMER_BASE_MONOTONIC_SOFT)
57#define HRTIMER_ACTIVE_HARD ((1U << MASK_SHIFT) - 1)
58#define HRTIMER_ACTIVE_SOFT (HRTIMER_ACTIVE_HARD << MASK_SHIFT)
59#define HRTIMER_ACTIVE_ALL (HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD)
60
61/*
62 * The timer bases:
63 *
64 * There are more clockids than hrtimer bases. Thus, we index
65 * into the timer bases by the hrtimer_base_type enum. When trying
66 * to reach a base using a clockid, hrtimer_clockid_to_base()
67 * is used to convert from clockid to the proper hrtimer_base_type.
68 */
69DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
70{
71 .lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
72 .clock_base =
73 {
74 {
75 .index = HRTIMER_BASE_MONOTONIC,
76 .clockid = CLOCK_MONOTONIC,
77 .get_time = &ktime_get,
78 },
79 {
80 .index = HRTIMER_BASE_REALTIME,
81 .clockid = CLOCK_REALTIME,
82 .get_time = &ktime_get_real,
83 },
84 {
85 .index = HRTIMER_BASE_BOOTTIME,
86 .clockid = CLOCK_BOOTTIME,
87 .get_time = &ktime_get_boottime,
88 },
89 {
90 .index = HRTIMER_BASE_TAI,
91 .clockid = CLOCK_TAI,
92 .get_time = &ktime_get_clocktai,
93 },
94 {
95 .index = HRTIMER_BASE_MONOTONIC_SOFT,
96 .clockid = CLOCK_MONOTONIC,
97 .get_time = &ktime_get,
98 },
99 {
100 .index = HRTIMER_BASE_REALTIME_SOFT,
101 .clockid = CLOCK_REALTIME,
102 .get_time = &ktime_get_real,
103 },
104 {
105 .index = HRTIMER_BASE_BOOTTIME_SOFT,
106 .clockid = CLOCK_BOOTTIME,
107 .get_time = &ktime_get_boottime,
108 },
109 {
110 .index = HRTIMER_BASE_TAI_SOFT,
111 .clockid = CLOCK_TAI,
112 .get_time = &ktime_get_clocktai,
113 },
114 }
115};
116
117static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
118 /* Make sure we catch unsupported clockids */
119 [0 ... MAX_CLOCKS - 1] = HRTIMER_MAX_CLOCK_BASES,
120
121 [CLOCK_REALTIME] = HRTIMER_BASE_REALTIME,
122 [CLOCK_MONOTONIC] = HRTIMER_BASE_MONOTONIC,
123 [CLOCK_BOOTTIME] = HRTIMER_BASE_BOOTTIME,
124 [CLOCK_TAI] = HRTIMER_BASE_TAI,
125};
126
127/*
128 * Functions and macros which are different for UP/SMP systems are kept in a
129 * single place
130 */
131#ifdef CONFIG_SMP
132
133/*
134 * We require the migration_base for lock_hrtimer_base()/switch_hrtimer_base()
135 * such that hrtimer_callback_running() can unconditionally dereference
136 * timer->base->cpu_base
137 */
138static struct hrtimer_cpu_base migration_cpu_base = {
139 .clock_base = { {
140 .cpu_base = &migration_cpu_base,
141 .seq = SEQCNT_RAW_SPINLOCK_ZERO(migration_cpu_base.seq,
142 &migration_cpu_base.lock),
143 }, },
144};
145
146#define migration_base migration_cpu_base.clock_base[0]
147
148static inline bool is_migration_base(struct hrtimer_clock_base *base)
149{
150 return base == &migration_base;
151}
152
153/*
154 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
155 * means that all timers which are tied to this base via timer->base are
156 * locked, and the base itself is locked too.
157 *
158 * So __run_timers/migrate_timers can safely modify all timers which could
159 * be found on the lists/queues.
160 *
161 * When the timer's base is locked, and the timer removed from list, it is
162 * possible to set timer->base = &migration_base and drop the lock: the timer
163 * remains locked.
164 */
165static
166struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
167 unsigned long *flags)
168 __acquires(&timer->base->lock)
169{
170 struct hrtimer_clock_base *base;
171
172 for (;;) {
173 base = READ_ONCE(timer->base);
174 if (likely(base != &migration_base)) {
175 raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
176 if (likely(base == timer->base))
177 return base;
178 /* The timer has migrated to another CPU: */
179 raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
180 }
181 cpu_relax();
182 }
183}
184
185/*
186 * We do not migrate the timer when it is expiring before the next
187 * event on the target cpu. When high resolution is enabled, we cannot
188 * reprogram the target cpu hardware and we would cause it to fire
189 * late. To keep it simple, we handle the high resolution enabled and
190 * disabled case similar.
191 *
192 * Called with cpu_base->lock of target cpu held.
193 */
194static int
195hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
196{
197 ktime_t expires;
198
199 expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
200 return expires < new_base->cpu_base->expires_next;
201}
202
203static inline
204struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
205 int pinned)
206{
207#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
208 if (static_branch_likely(&timers_migration_enabled) && !pinned)
209 return &per_cpu(hrtimer_bases, get_nohz_timer_target());
210#endif
211 return base;
212}
213
214/*
215 * We switch the timer base to a power-optimized selected CPU target,
216 * if:
217 * - NO_HZ_COMMON is enabled
218 * - timer migration is enabled
219 * - the timer callback is not running
220 * - the timer is not the first expiring timer on the new target
221 *
222 * If one of the above requirements is not fulfilled we move the timer
223 * to the current CPU or leave it on the previously assigned CPU if
224 * the timer callback is currently running.
225 */
226static inline struct hrtimer_clock_base *
227switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
228 int pinned)
229{
230 struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
231 struct hrtimer_clock_base *new_base;
232 int basenum = base->index;
233
234 this_cpu_base = this_cpu_ptr(&hrtimer_bases);
235 new_cpu_base = get_target_base(this_cpu_base, pinned);
236again:
237 new_base = &new_cpu_base->clock_base[basenum];
238
239 if (base != new_base) {
240 /*
241 * We are trying to move timer to new_base.
242 * However we can't change timer's base while it is running,
243 * so we keep it on the same CPU. No hassle vs. reprogramming
244 * the event source in the high resolution case. The softirq
245 * code will take care of this when the timer function has
246 * completed. There is no conflict as we hold the lock until
247 * the timer is enqueued.
248 */
249 if (unlikely(hrtimer_callback_running(timer)))
250 return base;
251
252 /* See the comment in lock_hrtimer_base() */
253 WRITE_ONCE(timer->base, &migration_base);
254 raw_spin_unlock(&base->cpu_base->lock);
255 raw_spin_lock(&new_base->cpu_base->lock);
256
257 if (new_cpu_base != this_cpu_base &&
258 hrtimer_check_target(timer, new_base)) {
259 raw_spin_unlock(&new_base->cpu_base->lock);
260 raw_spin_lock(&base->cpu_base->lock);
261 new_cpu_base = this_cpu_base;
262 WRITE_ONCE(timer->base, base);
263 goto again;
264 }
265 WRITE_ONCE(timer->base, new_base);
266 } else {
267 if (new_cpu_base != this_cpu_base &&
268 hrtimer_check_target(timer, new_base)) {
269 new_cpu_base = this_cpu_base;
270 goto again;
271 }
272 }
273 return new_base;
274}
275
276#else /* CONFIG_SMP */
277
278static inline bool is_migration_base(struct hrtimer_clock_base *base)
279{
280 return false;
281}
282
283static inline struct hrtimer_clock_base *
284lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
285 __acquires(&timer->base->cpu_base->lock)
286{
287 struct hrtimer_clock_base *base = timer->base;
288
289 raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
290
291 return base;
292}
293
294# define switch_hrtimer_base(t, b, p) (b)
295
296#endif /* !CONFIG_SMP */
297
298/*
299 * Functions for the union type storage format of ktime_t which are
300 * too large for inlining:
301 */
302#if BITS_PER_LONG < 64
303/*
304 * Divide a ktime value by a nanosecond value
305 */
306s64 __ktime_divns(const ktime_t kt, s64 div)
307{
308 int sft = 0;
309 s64 dclc;
310 u64 tmp;
311
312 dclc = ktime_to_ns(kt);
313 tmp = dclc < 0 ? -dclc : dclc;
314
315 /* Make sure the divisor is less than 2^32: */
316 while (div >> 32) {
317 sft++;
318 div >>= 1;
319 }
320 tmp >>= sft;
321 do_div(tmp, (u32) div);
322 return dclc < 0 ? -tmp : tmp;
323}
324EXPORT_SYMBOL_GPL(__ktime_divns);
325#endif /* BITS_PER_LONG >= 64 */
326
327/*
328 * Add two ktime values and do a safety check for overflow:
329 */
330ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
331{
332 ktime_t res = ktime_add_unsafe(lhs, rhs);
333
334 /*
335 * We use KTIME_SEC_MAX here, the maximum timeout which we can
336 * return to user space in a timespec:
337 */
338 if (res < 0 || res < lhs || res < rhs)
339 res = ktime_set(KTIME_SEC_MAX, 0);
340
341 return res;
342}
343
344EXPORT_SYMBOL_GPL(ktime_add_safe);
345
346#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
347
348static const struct debug_obj_descr hrtimer_debug_descr;
349
350static void *hrtimer_debug_hint(void *addr)
351{
352 return ((struct hrtimer *) addr)->function;
353}
354
355/*
356 * fixup_init is called when:
357 * - an active object is initialized
358 */
359static bool hrtimer_fixup_init(void *addr, enum debug_obj_state state)
360{
361 struct hrtimer *timer = addr;
362
363 switch (state) {
364 case ODEBUG_STATE_ACTIVE:
365 hrtimer_cancel(timer);
366 debug_object_init(timer, &hrtimer_debug_descr);
367 return true;
368 default:
369 return false;
370 }
371}
372
373/*
374 * fixup_activate is called when:
375 * - an active object is activated
376 * - an unknown non-static object is activated
377 */
378static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
379{
380 switch (state) {
381 case ODEBUG_STATE_ACTIVE:
382 WARN_ON(1);
383 fallthrough;
384 default:
385 return false;
386 }
387}
388
389/*
390 * fixup_free is called when:
391 * - an active object is freed
392 */
393static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state)
394{
395 struct hrtimer *timer = addr;
396
397 switch (state) {
398 case ODEBUG_STATE_ACTIVE:
399 hrtimer_cancel(timer);
400 debug_object_free(timer, &hrtimer_debug_descr);
401 return true;
402 default:
403 return false;
404 }
405}
406
407static const struct debug_obj_descr hrtimer_debug_descr = {
408 .name = "hrtimer",
409 .debug_hint = hrtimer_debug_hint,
410 .fixup_init = hrtimer_fixup_init,
411 .fixup_activate = hrtimer_fixup_activate,
412 .fixup_free = hrtimer_fixup_free,
413};
414
415static inline void debug_hrtimer_init(struct hrtimer *timer)
416{
417 debug_object_init(timer, &hrtimer_debug_descr);
418}
419
420static inline void debug_hrtimer_activate(struct hrtimer *timer,
421 enum hrtimer_mode mode)
422{
423 debug_object_activate(timer, &hrtimer_debug_descr);
424}
425
426static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
427{
428 debug_object_deactivate(timer, &hrtimer_debug_descr);
429}
430
431static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
432 enum hrtimer_mode mode);
433
434void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
435 enum hrtimer_mode mode)
436{
437 debug_object_init_on_stack(timer, &hrtimer_debug_descr);
438 __hrtimer_init(timer, clock_id, mode);
439}
440EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
441
442static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
443 clockid_t clock_id, enum hrtimer_mode mode);
444
445void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
446 clockid_t clock_id, enum hrtimer_mode mode)
447{
448 debug_object_init_on_stack(&sl->timer, &hrtimer_debug_descr);
449 __hrtimer_init_sleeper(sl, clock_id, mode);
450}
451EXPORT_SYMBOL_GPL(hrtimer_init_sleeper_on_stack);
452
453void destroy_hrtimer_on_stack(struct hrtimer *timer)
454{
455 debug_object_free(timer, &hrtimer_debug_descr);
456}
457EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
458
459#else
460
461static inline void debug_hrtimer_init(struct hrtimer *timer) { }
462static inline void debug_hrtimer_activate(struct hrtimer *timer,
463 enum hrtimer_mode mode) { }
464static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
465#endif
466
467static inline void
468debug_init(struct hrtimer *timer, clockid_t clockid,
469 enum hrtimer_mode mode)
470{
471 debug_hrtimer_init(timer);
472 trace_hrtimer_init(timer, clockid, mode);
473}
474
475static inline void debug_activate(struct hrtimer *timer,
476 enum hrtimer_mode mode)
477{
478 debug_hrtimer_activate(timer, mode);
479 trace_hrtimer_start(timer, mode);
480}
481
482static inline void debug_deactivate(struct hrtimer *timer)
483{
484 debug_hrtimer_deactivate(timer);
485 trace_hrtimer_cancel(timer);
486}
487
488static struct hrtimer_clock_base *
489__next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
490{
491 unsigned int idx;
492
493 if (!*active)
494 return NULL;
495
496 idx = __ffs(*active);
497 *active &= ~(1U << idx);
498
499 return &cpu_base->clock_base[idx];
500}
501
502#define for_each_active_base(base, cpu_base, active) \
503 while ((base = __next_base((cpu_base), &(active))))
504
505static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
506 const struct hrtimer *exclude,
507 unsigned int active,
508 ktime_t expires_next)
509{
510 struct hrtimer_clock_base *base;
511 ktime_t expires;
512
513 for_each_active_base(base, cpu_base, active) {
514 struct timerqueue_node *next;
515 struct hrtimer *timer;
516
517 next = timerqueue_getnext(&base->active);
518 timer = container_of(next, struct hrtimer, node);
519 if (timer == exclude) {
520 /* Get to the next timer in the queue. */
521 next = timerqueue_iterate_next(next);
522 if (!next)
523 continue;
524
525 timer = container_of(next, struct hrtimer, node);
526 }
527 expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
528 if (expires < expires_next) {
529 expires_next = expires;
530
531 /* Skip cpu_base update if a timer is being excluded. */
532 if (exclude)
533 continue;
534
535 if (timer->is_soft)
536 cpu_base->softirq_next_timer = timer;
537 else
538 cpu_base->next_timer = timer;
539 }
540 }
541 /*
542 * clock_was_set() might have changed base->offset of any of
543 * the clock bases so the result might be negative. Fix it up
544 * to prevent a false positive in clockevents_program_event().
545 */
546 if (expires_next < 0)
547 expires_next = 0;
548 return expires_next;
549}
550
551/*
552 * Recomputes cpu_base::*next_timer and returns the earliest expires_next
553 * but does not set cpu_base::*expires_next, that is done by
554 * hrtimer[_force]_reprogram and hrtimer_interrupt only. When updating
555 * cpu_base::*expires_next right away, reprogramming logic would no longer
556 * work.
557 *
558 * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
559 * those timers will get run whenever the softirq gets handled, at the end of
560 * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
561 *
562 * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
563 * The !softirq values are the minima across HRTIMER_ACTIVE_ALL, unless an actual
564 * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
565 *
566 * @active_mask must be one of:
567 * - HRTIMER_ACTIVE_ALL,
568 * - HRTIMER_ACTIVE_SOFT, or
569 * - HRTIMER_ACTIVE_HARD.
570 */
571static ktime_t
572__hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
573{
574 unsigned int active;
575 struct hrtimer *next_timer = NULL;
576 ktime_t expires_next = KTIME_MAX;
577
578 if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
579 active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
580 cpu_base->softirq_next_timer = NULL;
581 expires_next = __hrtimer_next_event_base(cpu_base, NULL,
582 active, KTIME_MAX);
583
584 next_timer = cpu_base->softirq_next_timer;
585 }
586
587 if (active_mask & HRTIMER_ACTIVE_HARD) {
588 active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
589 cpu_base->next_timer = next_timer;
590 expires_next = __hrtimer_next_event_base(cpu_base, NULL, active,
591 expires_next);
592 }
593
594 return expires_next;
595}
596
597static ktime_t hrtimer_update_next_event(struct hrtimer_cpu_base *cpu_base)
598{
599 ktime_t expires_next, soft = KTIME_MAX;
600
601 /*
602 * If the soft interrupt has already been activated, ignore the
603 * soft bases. They will be handled in the already raised soft
604 * interrupt.
605 */
606 if (!cpu_base->softirq_activated) {
607 soft = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
608 /*
609 * Update the soft expiry time. clock_settime() might have
610 * affected it.
611 */
612 cpu_base->softirq_expires_next = soft;
613 }
614
615 expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
616 /*
617 * If a softirq timer is expiring first, update cpu_base->next_timer
618 * and program the hardware with the soft expiry time.
619 */
620 if (expires_next > soft) {
621 cpu_base->next_timer = cpu_base->softirq_next_timer;
622 expires_next = soft;
623 }
624
625 return expires_next;
626}
627
628static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
629{
630 ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
631 ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
632 ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
633
634 ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
635 offs_real, offs_boot, offs_tai);
636
637 base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
638 base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
639 base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
640
641 return now;
642}
643
644/*
645 * Is the high resolution mode active ?
646 */
647static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
648{
649 return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
650 cpu_base->hres_active : 0;
651}
652
653static inline int hrtimer_hres_active(void)
654{
655 return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
656}
657
658static void __hrtimer_reprogram(struct hrtimer_cpu_base *cpu_base,
659 struct hrtimer *next_timer,
660 ktime_t expires_next)
661{
662 cpu_base->expires_next = expires_next;
663
664 /*
665 * If hres is not active, hardware does not have to be
666 * reprogrammed yet.
667 *
668 * If a hang was detected in the last timer interrupt then we
669 * leave the hang delay active in the hardware. We want the
670 * system to make progress. That also prevents the following
671 * scenario:
672 * T1 expires 50ms from now
673 * T2 expires 5s from now
674 *
675 * T1 is removed, so this code is called and would reprogram
676 * the hardware to 5s from now. Any hrtimer_start after that
677 * will not reprogram the hardware due to hang_detected being
678 * set. So we'd effectively block all timers until the T2 event
679 * fires.
680 */
681 if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
682 return;
683
684 tick_program_event(expires_next, 1);
685}
686
687/*
688 * Reprogram the event source with checking both queues for the
689 * next event
690 * Called with interrupts disabled and base->lock held
691 */
692static void
693hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
694{
695 ktime_t expires_next;
696
697 expires_next = hrtimer_update_next_event(cpu_base);
698
699 if (skip_equal && expires_next == cpu_base->expires_next)
700 return;
701
702 __hrtimer_reprogram(cpu_base, cpu_base->next_timer, expires_next);
703}
704
705/* High resolution timer related functions */
706#ifdef CONFIG_HIGH_RES_TIMERS
707
708/*
709 * High resolution timer enabled ?
710 */
711static bool hrtimer_hres_enabled __read_mostly = true;
712unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
713EXPORT_SYMBOL_GPL(hrtimer_resolution);
714
715/*
716 * Enable / Disable high resolution mode
717 */
718static int __init setup_hrtimer_hres(char *str)
719{
720 return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
721}
722
723__setup("highres=", setup_hrtimer_hres);
724
725/*
726 * hrtimer_high_res_enabled - query, if the highres mode is enabled
727 */
728static inline int hrtimer_is_hres_enabled(void)
729{
730 return hrtimer_hres_enabled;
731}
732
733static void retrigger_next_event(void *arg);
734
735/*
736 * Switch to high resolution mode
737 */
738static void hrtimer_switch_to_hres(void)
739{
740 struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
741
742 if (tick_init_highres()) {
743 pr_warn("Could not switch to high resolution mode on CPU %u\n",
744 base->cpu);
745 return;
746 }
747 base->hres_active = 1;
748 hrtimer_resolution = HIGH_RES_NSEC;
749
750 tick_setup_sched_timer(true);
751 /* "Retrigger" the interrupt to get things going */
752 retrigger_next_event(NULL);
753}
754
755#else
756
757static inline int hrtimer_is_hres_enabled(void) { return 0; }
758static inline void hrtimer_switch_to_hres(void) { }
759
760#endif /* CONFIG_HIGH_RES_TIMERS */
761/*
762 * Retrigger next event is called after clock was set with interrupts
763 * disabled through an SMP function call or directly from low level
764 * resume code.
765 *
766 * This is only invoked when:
767 * - CONFIG_HIGH_RES_TIMERS is enabled.
768 * - CONFIG_NOHZ_COMMON is enabled
769 *
770 * For the other cases this function is empty and because the call sites
771 * are optimized out it vanishes as well, i.e. no need for lots of
772 * #ifdeffery.
773 */
774static void retrigger_next_event(void *arg)
775{
776 struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
777
778 /*
779 * When high resolution mode or nohz is active, then the offsets of
780 * CLOCK_REALTIME/TAI/BOOTTIME have to be updated. Otherwise the
781 * next tick will take care of that.
782 *
783 * If high resolution mode is active then the next expiring timer
784 * must be reevaluated and the clock event device reprogrammed if
785 * necessary.
786 *
787 * In the NOHZ case the update of the offset and the reevaluation
788 * of the next expiring timer is enough. The return from the SMP
789 * function call will take care of the reprogramming in case the
790 * CPU was in a NOHZ idle sleep.
791 */
792 if (!__hrtimer_hres_active(base) && !tick_nohz_active)
793 return;
794
795 raw_spin_lock(&base->lock);
796 hrtimer_update_base(base);
797 if (__hrtimer_hres_active(base))
798 hrtimer_force_reprogram(base, 0);
799 else
800 hrtimer_update_next_event(base);
801 raw_spin_unlock(&base->lock);
802}
803
804/*
805 * When a timer is enqueued and expires earlier than the already enqueued
806 * timers, we have to check, whether it expires earlier than the timer for
807 * which the clock event device was armed.
808 *
809 * Called with interrupts disabled and base->cpu_base.lock held
810 */
811static void hrtimer_reprogram(struct hrtimer *timer, bool reprogram)
812{
813 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
814 struct hrtimer_clock_base *base = timer->base;
815 ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
816
817 WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
818
819 /*
820 * CLOCK_REALTIME timer might be requested with an absolute
821 * expiry time which is less than base->offset. Set it to 0.
822 */
823 if (expires < 0)
824 expires = 0;
825
826 if (timer->is_soft) {
827 /*
828 * soft hrtimer could be started on a remote CPU. In this
829 * case softirq_expires_next needs to be updated on the
830 * remote CPU. The soft hrtimer will not expire before the
831 * first hard hrtimer on the remote CPU -
832 * hrtimer_check_target() prevents this case.
833 */
834 struct hrtimer_cpu_base *timer_cpu_base = base->cpu_base;
835
836 if (timer_cpu_base->softirq_activated)
837 return;
838
839 if (!ktime_before(expires, timer_cpu_base->softirq_expires_next))
840 return;
841
842 timer_cpu_base->softirq_next_timer = timer;
843 timer_cpu_base->softirq_expires_next = expires;
844
845 if (!ktime_before(expires, timer_cpu_base->expires_next) ||
846 !reprogram)
847 return;
848 }
849
850 /*
851 * If the timer is not on the current cpu, we cannot reprogram
852 * the other cpus clock event device.
853 */
854 if (base->cpu_base != cpu_base)
855 return;
856
857 if (expires >= cpu_base->expires_next)
858 return;
859
860 /*
861 * If the hrtimer interrupt is running, then it will reevaluate the
862 * clock bases and reprogram the clock event device.
863 */
864 if (cpu_base->in_hrtirq)
865 return;
866
867 cpu_base->next_timer = timer;
868
869 __hrtimer_reprogram(cpu_base, timer, expires);
870}
871
872static bool update_needs_ipi(struct hrtimer_cpu_base *cpu_base,
873 unsigned int active)
874{
875 struct hrtimer_clock_base *base;
876 unsigned int seq;
877 ktime_t expires;
878
879 /*
880 * Update the base offsets unconditionally so the following
881 * checks whether the SMP function call is required works.
882 *
883 * The update is safe even when the remote CPU is in the hrtimer
884 * interrupt or the hrtimer soft interrupt and expiring affected
885 * bases. Either it will see the update before handling a base or
886 * it will see it when it finishes the processing and reevaluates
887 * the next expiring timer.
888 */
889 seq = cpu_base->clock_was_set_seq;
890 hrtimer_update_base(cpu_base);
891
892 /*
893 * If the sequence did not change over the update then the
894 * remote CPU already handled it.
895 */
896 if (seq == cpu_base->clock_was_set_seq)
897 return false;
898
899 /*
900 * If the remote CPU is currently handling an hrtimer interrupt, it
901 * will reevaluate the first expiring timer of all clock bases
902 * before reprogramming. Nothing to do here.
903 */
904 if (cpu_base->in_hrtirq)
905 return false;
906
907 /*
908 * Walk the affected clock bases and check whether the first expiring
909 * timer in a clock base is moving ahead of the first expiring timer of
910 * @cpu_base. If so, the IPI must be invoked because per CPU clock
911 * event devices cannot be remotely reprogrammed.
912 */
913 active &= cpu_base->active_bases;
914
915 for_each_active_base(base, cpu_base, active) {
916 struct timerqueue_node *next;
917
918 next = timerqueue_getnext(&base->active);
919 expires = ktime_sub(next->expires, base->offset);
920 if (expires < cpu_base->expires_next)
921 return true;
922
923 /* Extra check for softirq clock bases */
924 if (base->clockid < HRTIMER_BASE_MONOTONIC_SOFT)
925 continue;
926 if (cpu_base->softirq_activated)
927 continue;
928 if (expires < cpu_base->softirq_expires_next)
929 return true;
930 }
931 return false;
932}
933
934/*
935 * Clock was set. This might affect CLOCK_REALTIME, CLOCK_TAI and
936 * CLOCK_BOOTTIME (for late sleep time injection).
937 *
938 * This requires to update the offsets for these clocks
939 * vs. CLOCK_MONOTONIC. When high resolution timers are enabled, then this
940 * also requires to eventually reprogram the per CPU clock event devices
941 * when the change moves an affected timer ahead of the first expiring
942 * timer on that CPU. Obviously remote per CPU clock event devices cannot
943 * be reprogrammed. The other reason why an IPI has to be sent is when the
944 * system is in !HIGH_RES and NOHZ mode. The NOHZ mode updates the offsets
945 * in the tick, which obviously might be stopped, so this has to bring out
946 * the remote CPU which might sleep in idle to get this sorted.
947 */
948void clock_was_set(unsigned int bases)
949{
950 struct hrtimer_cpu_base *cpu_base = raw_cpu_ptr(&hrtimer_bases);
951 cpumask_var_t mask;
952 int cpu;
953
954 if (!__hrtimer_hres_active(cpu_base) && !tick_nohz_active)
955 goto out_timerfd;
956
957 if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
958 on_each_cpu(retrigger_next_event, NULL, 1);
959 goto out_timerfd;
960 }
961
962 /* Avoid interrupting CPUs if possible */
963 cpus_read_lock();
964 for_each_online_cpu(cpu) {
965 unsigned long flags;
966
967 cpu_base = &per_cpu(hrtimer_bases, cpu);
968 raw_spin_lock_irqsave(&cpu_base->lock, flags);
969
970 if (update_needs_ipi(cpu_base, bases))
971 cpumask_set_cpu(cpu, mask);
972
973 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
974 }
975
976 preempt_disable();
977 smp_call_function_many(mask, retrigger_next_event, NULL, 1);
978 preempt_enable();
979 cpus_read_unlock();
980 free_cpumask_var(mask);
981
982out_timerfd:
983 timerfd_clock_was_set();
984}
985
986static void clock_was_set_work(struct work_struct *work)
987{
988 clock_was_set(CLOCK_SET_WALL);
989}
990
991static DECLARE_WORK(hrtimer_work, clock_was_set_work);
992
993/*
994 * Called from timekeeping code to reprogram the hrtimer interrupt device
995 * on all cpus and to notify timerfd.
996 */
997void clock_was_set_delayed(void)
998{
999 schedule_work(&hrtimer_work);
1000}
1001
1002/*
1003 * Called during resume either directly from via timekeeping_resume()
1004 * or in the case of s2idle from tick_unfreeze() to ensure that the
1005 * hrtimers are up to date.
1006 */
1007void hrtimers_resume_local(void)
1008{
1009 lockdep_assert_irqs_disabled();
1010 /* Retrigger on the local CPU */
1011 retrigger_next_event(NULL);
1012}
1013
1014/*
1015 * Counterpart to lock_hrtimer_base above:
1016 */
1017static inline
1018void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
1019 __releases(&timer->base->cpu_base->lock)
1020{
1021 raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
1022}
1023
1024/**
1025 * hrtimer_forward() - forward the timer expiry
1026 * @timer: hrtimer to forward
1027 * @now: forward past this time
1028 * @interval: the interval to forward
1029 *
1030 * Forward the timer expiry so it will expire in the future.
1031 *
1032 * .. note::
1033 * This only updates the timer expiry value and does not requeue the timer.
1034 *
1035 * There is also a variant of the function hrtimer_forward_now().
1036 *
1037 * Context: Can be safely called from the callback function of @timer. If called
1038 * from other contexts @timer must neither be enqueued nor running the
1039 * callback and the caller needs to take care of serialization.
1040 *
1041 * Return: The number of overruns are returned.
1042 */
1043u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
1044{
1045 u64 orun = 1;
1046 ktime_t delta;
1047
1048 delta = ktime_sub(now, hrtimer_get_expires(timer));
1049
1050 if (delta < 0)
1051 return 0;
1052
1053 if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
1054 return 0;
1055
1056 if (interval < hrtimer_resolution)
1057 interval = hrtimer_resolution;
1058
1059 if (unlikely(delta >= interval)) {
1060 s64 incr = ktime_to_ns(interval);
1061
1062 orun = ktime_divns(delta, incr);
1063 hrtimer_add_expires_ns(timer, incr * orun);
1064 if (hrtimer_get_expires_tv64(timer) > now)
1065 return orun;
1066 /*
1067 * This (and the ktime_add() below) is the
1068 * correction for exact:
1069 */
1070 orun++;
1071 }
1072 hrtimer_add_expires(timer, interval);
1073
1074 return orun;
1075}
1076EXPORT_SYMBOL_GPL(hrtimer_forward);
1077
1078/*
1079 * enqueue_hrtimer - internal function to (re)start a timer
1080 *
1081 * The timer is inserted in expiry order. Insertion into the
1082 * red black tree is O(log(n)). Must hold the base lock.
1083 *
1084 * Returns 1 when the new timer is the leftmost timer in the tree.
1085 */
1086static int enqueue_hrtimer(struct hrtimer *timer,
1087 struct hrtimer_clock_base *base,
1088 enum hrtimer_mode mode)
1089{
1090 debug_activate(timer, mode);
1091 WARN_ON_ONCE(!base->cpu_base->online);
1092
1093 base->cpu_base->active_bases |= 1 << base->index;
1094
1095 /* Pairs with the lockless read in hrtimer_is_queued() */
1096 WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
1097
1098 return timerqueue_add(&base->active, &timer->node);
1099}
1100
1101/*
1102 * __remove_hrtimer - internal function to remove a timer
1103 *
1104 * Caller must hold the base lock.
1105 *
1106 * High resolution timer mode reprograms the clock event device when the
1107 * timer is the one which expires next. The caller can disable this by setting
1108 * reprogram to zero. This is useful, when the context does a reprogramming
1109 * anyway (e.g. timer interrupt)
1110 */
1111static void __remove_hrtimer(struct hrtimer *timer,
1112 struct hrtimer_clock_base *base,
1113 u8 newstate, int reprogram)
1114{
1115 struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1116 u8 state = timer->state;
1117
1118 /* Pairs with the lockless read in hrtimer_is_queued() */
1119 WRITE_ONCE(timer->state, newstate);
1120 if (!(state & HRTIMER_STATE_ENQUEUED))
1121 return;
1122
1123 if (!timerqueue_del(&base->active, &timer->node))
1124 cpu_base->active_bases &= ~(1 << base->index);
1125
1126 /*
1127 * Note: If reprogram is false we do not update
1128 * cpu_base->next_timer. This happens when we remove the first
1129 * timer on a remote cpu. No harm as we never dereference
1130 * cpu_base->next_timer. So the worst thing what can happen is
1131 * an superfluous call to hrtimer_force_reprogram() on the
1132 * remote cpu later on if the same timer gets enqueued again.
1133 */
1134 if (reprogram && timer == cpu_base->next_timer)
1135 hrtimer_force_reprogram(cpu_base, 1);
1136}
1137
1138/*
1139 * remove hrtimer, called with base lock held
1140 */
1141static inline int
1142remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base,
1143 bool restart, bool keep_local)
1144{
1145 u8 state = timer->state;
1146
1147 if (state & HRTIMER_STATE_ENQUEUED) {
1148 bool reprogram;
1149
1150 /*
1151 * Remove the timer and force reprogramming when high
1152 * resolution mode is active and the timer is on the current
1153 * CPU. If we remove a timer on another CPU, reprogramming is
1154 * skipped. The interrupt event on this CPU is fired and
1155 * reprogramming happens in the interrupt handler. This is a
1156 * rare case and less expensive than a smp call.
1157 */
1158 debug_deactivate(timer);
1159 reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1160
1161 /*
1162 * If the timer is not restarted then reprogramming is
1163 * required if the timer is local. If it is local and about
1164 * to be restarted, avoid programming it twice (on removal
1165 * and a moment later when it's requeued).
1166 */
1167 if (!restart)
1168 state = HRTIMER_STATE_INACTIVE;
1169 else
1170 reprogram &= !keep_local;
1171
1172 __remove_hrtimer(timer, base, state, reprogram);
1173 return 1;
1174 }
1175 return 0;
1176}
1177
1178static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
1179 const enum hrtimer_mode mode)
1180{
1181#ifdef CONFIG_TIME_LOW_RES
1182 /*
1183 * CONFIG_TIME_LOW_RES indicates that the system has no way to return
1184 * granular time values. For relative timers we add hrtimer_resolution
1185 * (i.e. one jiffie) to prevent short timeouts.
1186 */
1187 timer->is_rel = mode & HRTIMER_MODE_REL;
1188 if (timer->is_rel)
1189 tim = ktime_add_safe(tim, hrtimer_resolution);
1190#endif
1191 return tim;
1192}
1193
1194static void
1195hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
1196{
1197 ktime_t expires;
1198
1199 /*
1200 * Find the next SOFT expiration.
1201 */
1202 expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
1203
1204 /*
1205 * reprogramming needs to be triggered, even if the next soft
1206 * hrtimer expires at the same time than the next hard
1207 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
1208 */
1209 if (expires == KTIME_MAX)
1210 return;
1211
1212 /*
1213 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
1214 * cpu_base->*expires_next is only set by hrtimer_reprogram()
1215 */
1216 hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
1217}
1218
1219static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1220 u64 delta_ns, const enum hrtimer_mode mode,
1221 struct hrtimer_clock_base *base)
1222{
1223 struct hrtimer_clock_base *new_base;
1224 bool force_local, first;
1225
1226 /*
1227 * If the timer is on the local cpu base and is the first expiring
1228 * timer then this might end up reprogramming the hardware twice
1229 * (on removal and on enqueue). To avoid that by prevent the
1230 * reprogram on removal, keep the timer local to the current CPU
1231 * and enforce reprogramming after it is queued no matter whether
1232 * it is the new first expiring timer again or not.
1233 */
1234 force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1235 force_local &= base->cpu_base->next_timer == timer;
1236
1237 /*
1238 * Remove an active timer from the queue. In case it is not queued
1239 * on the current CPU, make sure that remove_hrtimer() updates the
1240 * remote data correctly.
1241 *
1242 * If it's on the current CPU and the first expiring timer, then
1243 * skip reprogramming, keep the timer local and enforce
1244 * reprogramming later if it was the first expiring timer. This
1245 * avoids programming the underlying clock event twice (once at
1246 * removal and once after enqueue).
1247 */
1248 remove_hrtimer(timer, base, true, force_local);
1249
1250 if (mode & HRTIMER_MODE_REL)
1251 tim = ktime_add_safe(tim, base->get_time());
1252
1253 tim = hrtimer_update_lowres(timer, tim, mode);
1254
1255 hrtimer_set_expires_range_ns(timer, tim, delta_ns);
1256
1257 /* Switch the timer base, if necessary: */
1258 if (!force_local) {
1259 new_base = switch_hrtimer_base(timer, base,
1260 mode & HRTIMER_MODE_PINNED);
1261 } else {
1262 new_base = base;
1263 }
1264
1265 first = enqueue_hrtimer(timer, new_base, mode);
1266 if (!force_local)
1267 return first;
1268
1269 /*
1270 * Timer was forced to stay on the current CPU to avoid
1271 * reprogramming on removal and enqueue. Force reprogram the
1272 * hardware by evaluating the new first expiring timer.
1273 */
1274 hrtimer_force_reprogram(new_base->cpu_base, 1);
1275 return 0;
1276}
1277
1278/**
1279 * hrtimer_start_range_ns - (re)start an hrtimer
1280 * @timer: the timer to be added
1281 * @tim: expiry time
1282 * @delta_ns: "slack" range for the timer
1283 * @mode: timer mode: absolute (HRTIMER_MODE_ABS) or
1284 * relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
1285 * softirq based mode is considered for debug purpose only!
1286 */
1287void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1288 u64 delta_ns, const enum hrtimer_mode mode)
1289{
1290 struct hrtimer_clock_base *base;
1291 unsigned long flags;
1292
1293 /*
1294 * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
1295 * match on CONFIG_PREEMPT_RT = n. With PREEMPT_RT check the hard
1296 * expiry mode because unmarked timers are moved to softirq expiry.
1297 */
1298 if (!IS_ENABLED(CONFIG_PREEMPT_RT))
1299 WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
1300 else
1301 WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard);
1302
1303 base = lock_hrtimer_base(timer, &flags);
1304
1305 if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
1306 hrtimer_reprogram(timer, true);
1307
1308 unlock_hrtimer_base(timer, &flags);
1309}
1310EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1311
1312/**
1313 * hrtimer_try_to_cancel - try to deactivate a timer
1314 * @timer: hrtimer to stop
1315 *
1316 * Returns:
1317 *
1318 * * 0 when the timer was not active
1319 * * 1 when the timer was active
1320 * * -1 when the timer is currently executing the callback function and
1321 * cannot be stopped
1322 */
1323int hrtimer_try_to_cancel(struct hrtimer *timer)
1324{
1325 struct hrtimer_clock_base *base;
1326 unsigned long flags;
1327 int ret = -1;
1328
1329 /*
1330 * Check lockless first. If the timer is not active (neither
1331 * enqueued nor running the callback, nothing to do here. The
1332 * base lock does not serialize against a concurrent enqueue,
1333 * so we can avoid taking it.
1334 */
1335 if (!hrtimer_active(timer))
1336 return 0;
1337
1338 base = lock_hrtimer_base(timer, &flags);
1339
1340 if (!hrtimer_callback_running(timer))
1341 ret = remove_hrtimer(timer, base, false, false);
1342
1343 unlock_hrtimer_base(timer, &flags);
1344
1345 return ret;
1346
1347}
1348EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1349
1350#ifdef CONFIG_PREEMPT_RT
1351static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
1352{
1353 spin_lock_init(&base->softirq_expiry_lock);
1354}
1355
1356static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
1357{
1358 spin_lock(&base->softirq_expiry_lock);
1359}
1360
1361static void hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base)
1362{
1363 spin_unlock(&base->softirq_expiry_lock);
1364}
1365
1366/*
1367 * The counterpart to hrtimer_cancel_wait_running().
1368 *
1369 * If there is a waiter for cpu_base->expiry_lock, then it was waiting for
1370 * the timer callback to finish. Drop expiry_lock and reacquire it. That
1371 * allows the waiter to acquire the lock and make progress.
1372 */
1373static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base,
1374 unsigned long flags)
1375{
1376 if (atomic_read(&cpu_base->timer_waiters)) {
1377 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1378 spin_unlock(&cpu_base->softirq_expiry_lock);
1379 spin_lock(&cpu_base->softirq_expiry_lock);
1380 raw_spin_lock_irq(&cpu_base->lock);
1381 }
1382}
1383
1384/*
1385 * This function is called on PREEMPT_RT kernels when the fast path
1386 * deletion of a timer failed because the timer callback function was
1387 * running.
1388 *
1389 * This prevents priority inversion: if the soft irq thread is preempted
1390 * in the middle of a timer callback, then calling del_timer_sync() can
1391 * lead to two issues:
1392 *
1393 * - If the caller is on a remote CPU then it has to spin wait for the timer
1394 * handler to complete. This can result in unbound priority inversion.
1395 *
1396 * - If the caller originates from the task which preempted the timer
1397 * handler on the same CPU, then spin waiting for the timer handler to
1398 * complete is never going to end.
1399 */
1400void hrtimer_cancel_wait_running(const struct hrtimer *timer)
1401{
1402 /* Lockless read. Prevent the compiler from reloading it below */
1403 struct hrtimer_clock_base *base = READ_ONCE(timer->base);
1404
1405 /*
1406 * Just relax if the timer expires in hard interrupt context or if
1407 * it is currently on the migration base.
1408 */
1409 if (!timer->is_soft || is_migration_base(base)) {
1410 cpu_relax();
1411 return;
1412 }
1413
1414 /*
1415 * Mark the base as contended and grab the expiry lock, which is
1416 * held by the softirq across the timer callback. Drop the lock
1417 * immediately so the softirq can expire the next timer. In theory
1418 * the timer could already be running again, but that's more than
1419 * unlikely and just causes another wait loop.
1420 */
1421 atomic_inc(&base->cpu_base->timer_waiters);
1422 spin_lock_bh(&base->cpu_base->softirq_expiry_lock);
1423 atomic_dec(&base->cpu_base->timer_waiters);
1424 spin_unlock_bh(&base->cpu_base->softirq_expiry_lock);
1425}
1426#else
1427static inline void
1428hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
1429static inline void
1430hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
1431static inline void
1432hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
1433static inline void hrtimer_sync_wait_running(struct hrtimer_cpu_base *base,
1434 unsigned long flags) { }
1435#endif
1436
1437/**
1438 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1439 * @timer: the timer to be cancelled
1440 *
1441 * Returns:
1442 * 0 when the timer was not active
1443 * 1 when the timer was active
1444 */
1445int hrtimer_cancel(struct hrtimer *timer)
1446{
1447 int ret;
1448
1449 do {
1450 ret = hrtimer_try_to_cancel(timer);
1451
1452 if (ret < 0)
1453 hrtimer_cancel_wait_running(timer);
1454 } while (ret < 0);
1455 return ret;
1456}
1457EXPORT_SYMBOL_GPL(hrtimer_cancel);
1458
1459/**
1460 * __hrtimer_get_remaining - get remaining time for the timer
1461 * @timer: the timer to read
1462 * @adjust: adjust relative timers when CONFIG_TIME_LOW_RES=y
1463 */
1464ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
1465{
1466 unsigned long flags;
1467 ktime_t rem;
1468
1469 lock_hrtimer_base(timer, &flags);
1470 if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
1471 rem = hrtimer_expires_remaining_adjusted(timer);
1472 else
1473 rem = hrtimer_expires_remaining(timer);
1474 unlock_hrtimer_base(timer, &flags);
1475
1476 return rem;
1477}
1478EXPORT_SYMBOL_GPL(__hrtimer_get_remaining);
1479
1480#ifdef CONFIG_NO_HZ_COMMON
1481/**
1482 * hrtimer_get_next_event - get the time until next expiry event
1483 *
1484 * Returns the next expiry time or KTIME_MAX if no timer is pending.
1485 */
1486u64 hrtimer_get_next_event(void)
1487{
1488 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1489 u64 expires = KTIME_MAX;
1490 unsigned long flags;
1491
1492 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1493
1494 if (!__hrtimer_hres_active(cpu_base))
1495 expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
1496
1497 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1498
1499 return expires;
1500}
1501
1502/**
1503 * hrtimer_next_event_without - time until next expiry event w/o one timer
1504 * @exclude: timer to exclude
1505 *
1506 * Returns the next expiry time over all timers except for the @exclude one or
1507 * KTIME_MAX if none of them is pending.
1508 */
1509u64 hrtimer_next_event_without(const struct hrtimer *exclude)
1510{
1511 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1512 u64 expires = KTIME_MAX;
1513 unsigned long flags;
1514
1515 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1516
1517 if (__hrtimer_hres_active(cpu_base)) {
1518 unsigned int active;
1519
1520 if (!cpu_base->softirq_activated) {
1521 active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
1522 expires = __hrtimer_next_event_base(cpu_base, exclude,
1523 active, KTIME_MAX);
1524 }
1525 active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
1526 expires = __hrtimer_next_event_base(cpu_base, exclude, active,
1527 expires);
1528 }
1529
1530 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1531
1532 return expires;
1533}
1534#endif
1535
1536static inline int hrtimer_clockid_to_base(clockid_t clock_id)
1537{
1538 if (likely(clock_id < MAX_CLOCKS)) {
1539 int base = hrtimer_clock_to_base_table[clock_id];
1540
1541 if (likely(base != HRTIMER_MAX_CLOCK_BASES))
1542 return base;
1543 }
1544 WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
1545 return HRTIMER_BASE_MONOTONIC;
1546}
1547
1548static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1549 enum hrtimer_mode mode)
1550{
1551 bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
1552 struct hrtimer_cpu_base *cpu_base;
1553 int base;
1554
1555 /*
1556 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1557 * marked for hard interrupt expiry mode are moved into soft
1558 * interrupt context for latency reasons and because the callbacks
1559 * can invoke functions which might sleep on RT, e.g. spin_lock().
1560 */
1561 if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD))
1562 softtimer = true;
1563
1564 memset(timer, 0, sizeof(struct hrtimer));
1565
1566 cpu_base = raw_cpu_ptr(&hrtimer_bases);
1567
1568 /*
1569 * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
1570 * clock modifications, so they needs to become CLOCK_MONOTONIC to
1571 * ensure POSIX compliance.
1572 */
1573 if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
1574 clock_id = CLOCK_MONOTONIC;
1575
1576 base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
1577 base += hrtimer_clockid_to_base(clock_id);
1578 timer->is_soft = softtimer;
1579 timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
1580 timer->base = &cpu_base->clock_base[base];
1581 timerqueue_init(&timer->node);
1582}
1583
1584/**
1585 * hrtimer_init - initialize a timer to the given clock
1586 * @timer: the timer to be initialized
1587 * @clock_id: the clock to be used
1588 * @mode: The modes which are relevant for initialization:
1589 * HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
1590 * HRTIMER_MODE_REL_SOFT
1591 *
1592 * The PINNED variants of the above can be handed in,
1593 * but the PINNED bit is ignored as pinning happens
1594 * when the hrtimer is started
1595 */
1596void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1597 enum hrtimer_mode mode)
1598{
1599 debug_init(timer, clock_id, mode);
1600 __hrtimer_init(timer, clock_id, mode);
1601}
1602EXPORT_SYMBOL_GPL(hrtimer_init);
1603
1604/*
1605 * A timer is active, when it is enqueued into the rbtree or the
1606 * callback function is running or it's in the state of being migrated
1607 * to another cpu.
1608 *
1609 * It is important for this function to not return a false negative.
1610 */
1611bool hrtimer_active(const struct hrtimer *timer)
1612{
1613 struct hrtimer_clock_base *base;
1614 unsigned int seq;
1615
1616 do {
1617 base = READ_ONCE(timer->base);
1618 seq = raw_read_seqcount_begin(&base->seq);
1619
1620 if (timer->state != HRTIMER_STATE_INACTIVE ||
1621 base->running == timer)
1622 return true;
1623
1624 } while (read_seqcount_retry(&base->seq, seq) ||
1625 base != READ_ONCE(timer->base));
1626
1627 return false;
1628}
1629EXPORT_SYMBOL_GPL(hrtimer_active);
1630
1631/*
1632 * The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
1633 * distinct sections:
1634 *
1635 * - queued: the timer is queued
1636 * - callback: the timer is being ran
1637 * - post: the timer is inactive or (re)queued
1638 *
1639 * On the read side we ensure we observe timer->state and cpu_base->running
1640 * from the same section, if anything changed while we looked at it, we retry.
1641 * This includes timer->base changing because sequence numbers alone are
1642 * insufficient for that.
1643 *
1644 * The sequence numbers are required because otherwise we could still observe
1645 * a false negative if the read side got smeared over multiple consecutive
1646 * __run_hrtimer() invocations.
1647 */
1648
1649static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
1650 struct hrtimer_clock_base *base,
1651 struct hrtimer *timer, ktime_t *now,
1652 unsigned long flags) __must_hold(&cpu_base->lock)
1653{
1654 enum hrtimer_restart (*fn)(struct hrtimer *);
1655 bool expires_in_hardirq;
1656 int restart;
1657
1658 lockdep_assert_held(&cpu_base->lock);
1659
1660 debug_deactivate(timer);
1661 base->running = timer;
1662
1663 /*
1664 * Separate the ->running assignment from the ->state assignment.
1665 *
1666 * As with a regular write barrier, this ensures the read side in
1667 * hrtimer_active() cannot observe base->running == NULL &&
1668 * timer->state == INACTIVE.
1669 */
1670 raw_write_seqcount_barrier(&base->seq);
1671
1672 __remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
1673 fn = timer->function;
1674
1675 /*
1676 * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
1677 * timer is restarted with a period then it becomes an absolute
1678 * timer. If its not restarted it does not matter.
1679 */
1680 if (IS_ENABLED(CONFIG_TIME_LOW_RES))
1681 timer->is_rel = false;
1682
1683 /*
1684 * The timer is marked as running in the CPU base, so it is
1685 * protected against migration to a different CPU even if the lock
1686 * is dropped.
1687 */
1688 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1689 trace_hrtimer_expire_entry(timer, now);
1690 expires_in_hardirq = lockdep_hrtimer_enter(timer);
1691
1692 restart = fn(timer);
1693
1694 lockdep_hrtimer_exit(expires_in_hardirq);
1695 trace_hrtimer_expire_exit(timer);
1696 raw_spin_lock_irq(&cpu_base->lock);
1697
1698 /*
1699 * Note: We clear the running state after enqueue_hrtimer and
1700 * we do not reprogram the event hardware. Happens either in
1701 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1702 *
1703 * Note: Because we dropped the cpu_base->lock above,
1704 * hrtimer_start_range_ns() can have popped in and enqueued the timer
1705 * for us already.
1706 */
1707 if (restart != HRTIMER_NORESTART &&
1708 !(timer->state & HRTIMER_STATE_ENQUEUED))
1709 enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
1710
1711 /*
1712 * Separate the ->running assignment from the ->state assignment.
1713 *
1714 * As with a regular write barrier, this ensures the read side in
1715 * hrtimer_active() cannot observe base->running.timer == NULL &&
1716 * timer->state == INACTIVE.
1717 */
1718 raw_write_seqcount_barrier(&base->seq);
1719
1720 WARN_ON_ONCE(base->running != timer);
1721 base->running = NULL;
1722}
1723
1724static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
1725 unsigned long flags, unsigned int active_mask)
1726{
1727 struct hrtimer_clock_base *base;
1728 unsigned int active = cpu_base->active_bases & active_mask;
1729
1730 for_each_active_base(base, cpu_base, active) {
1731 struct timerqueue_node *node;
1732 ktime_t basenow;
1733
1734 basenow = ktime_add(now, base->offset);
1735
1736 while ((node = timerqueue_getnext(&base->active))) {
1737 struct hrtimer *timer;
1738
1739 timer = container_of(node, struct hrtimer, node);
1740
1741 /*
1742 * The immediate goal for using the softexpires is
1743 * minimizing wakeups, not running timers at the
1744 * earliest interrupt after their soft expiration.
1745 * This allows us to avoid using a Priority Search
1746 * Tree, which can answer a stabbing query for
1747 * overlapping intervals and instead use the simple
1748 * BST we already have.
1749 * We don't add extra wakeups by delaying timers that
1750 * are right-of a not yet expired timer, because that
1751 * timer will have to trigger a wakeup anyway.
1752 */
1753 if (basenow < hrtimer_get_softexpires_tv64(timer))
1754 break;
1755
1756 __run_hrtimer(cpu_base, base, timer, &basenow, flags);
1757 if (active_mask == HRTIMER_ACTIVE_SOFT)
1758 hrtimer_sync_wait_running(cpu_base, flags);
1759 }
1760 }
1761}
1762
1763static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
1764{
1765 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1766 unsigned long flags;
1767 ktime_t now;
1768
1769 hrtimer_cpu_base_lock_expiry(cpu_base);
1770 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1771
1772 now = hrtimer_update_base(cpu_base);
1773 __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
1774
1775 cpu_base->softirq_activated = 0;
1776 hrtimer_update_softirq_timer(cpu_base, true);
1777
1778 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1779 hrtimer_cpu_base_unlock_expiry(cpu_base);
1780}
1781
1782#ifdef CONFIG_HIGH_RES_TIMERS
1783
1784/*
1785 * High resolution timer interrupt
1786 * Called with interrupts disabled
1787 */
1788void hrtimer_interrupt(struct clock_event_device *dev)
1789{
1790 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1791 ktime_t expires_next, now, entry_time, delta;
1792 unsigned long flags;
1793 int retries = 0;
1794
1795 BUG_ON(!cpu_base->hres_active);
1796 cpu_base->nr_events++;
1797 dev->next_event = KTIME_MAX;
1798
1799 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1800 entry_time = now = hrtimer_update_base(cpu_base);
1801retry:
1802 cpu_base->in_hrtirq = 1;
1803 /*
1804 * We set expires_next to KTIME_MAX here with cpu_base->lock
1805 * held to prevent that a timer is enqueued in our queue via
1806 * the migration code. This does not affect enqueueing of
1807 * timers which run their callback and need to be requeued on
1808 * this CPU.
1809 */
1810 cpu_base->expires_next = KTIME_MAX;
1811
1812 if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1813 cpu_base->softirq_expires_next = KTIME_MAX;
1814 cpu_base->softirq_activated = 1;
1815 raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1816 }
1817
1818 __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1819
1820 /* Reevaluate the clock bases for the [soft] next expiry */
1821 expires_next = hrtimer_update_next_event(cpu_base);
1822 /*
1823 * Store the new expiry value so the migration code can verify
1824 * against it.
1825 */
1826 cpu_base->expires_next = expires_next;
1827 cpu_base->in_hrtirq = 0;
1828 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1829
1830 /* Reprogramming necessary ? */
1831 if (!tick_program_event(expires_next, 0)) {
1832 cpu_base->hang_detected = 0;
1833 return;
1834 }
1835
1836 /*
1837 * The next timer was already expired due to:
1838 * - tracing
1839 * - long lasting callbacks
1840 * - being scheduled away when running in a VM
1841 *
1842 * We need to prevent that we loop forever in the hrtimer
1843 * interrupt routine. We give it 3 attempts to avoid
1844 * overreacting on some spurious event.
1845 *
1846 * Acquire base lock for updating the offsets and retrieving
1847 * the current time.
1848 */
1849 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1850 now = hrtimer_update_base(cpu_base);
1851 cpu_base->nr_retries++;
1852 if (++retries < 3)
1853 goto retry;
1854 /*
1855 * Give the system a chance to do something else than looping
1856 * here. We stored the entry time, so we know exactly how long
1857 * we spent here. We schedule the next event this amount of
1858 * time away.
1859 */
1860 cpu_base->nr_hangs++;
1861 cpu_base->hang_detected = 1;
1862 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1863
1864 delta = ktime_sub(now, entry_time);
1865 if ((unsigned int)delta > cpu_base->max_hang_time)
1866 cpu_base->max_hang_time = (unsigned int) delta;
1867 /*
1868 * Limit it to a sensible value as we enforce a longer
1869 * delay. Give the CPU at least 100ms to catch up.
1870 */
1871 if (delta > 100 * NSEC_PER_MSEC)
1872 expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1873 else
1874 expires_next = ktime_add(now, delta);
1875 tick_program_event(expires_next, 1);
1876 pr_warn_once("hrtimer: interrupt took %llu ns\n", ktime_to_ns(delta));
1877}
1878
1879/* called with interrupts disabled */
1880static inline void __hrtimer_peek_ahead_timers(void)
1881{
1882 struct tick_device *td;
1883
1884 if (!hrtimer_hres_active())
1885 return;
1886
1887 td = this_cpu_ptr(&tick_cpu_device);
1888 if (td && td->evtdev)
1889 hrtimer_interrupt(td->evtdev);
1890}
1891
1892#else /* CONFIG_HIGH_RES_TIMERS */
1893
1894static inline void __hrtimer_peek_ahead_timers(void) { }
1895
1896#endif /* !CONFIG_HIGH_RES_TIMERS */
1897
1898/*
1899 * Called from run_local_timers in hardirq context every jiffy
1900 */
1901void hrtimer_run_queues(void)
1902{
1903 struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1904 unsigned long flags;
1905 ktime_t now;
1906
1907 if (__hrtimer_hres_active(cpu_base))
1908 return;
1909
1910 /*
1911 * This _is_ ugly: We have to check periodically, whether we
1912 * can switch to highres and / or nohz mode. The clocksource
1913 * switch happens with xtime_lock held. Notification from
1914 * there only sets the check bit in the tick_oneshot code,
1915 * otherwise we might deadlock vs. xtime_lock.
1916 */
1917 if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
1918 hrtimer_switch_to_hres();
1919 return;
1920 }
1921
1922 raw_spin_lock_irqsave(&cpu_base->lock, flags);
1923 now = hrtimer_update_base(cpu_base);
1924
1925 if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1926 cpu_base->softirq_expires_next = KTIME_MAX;
1927 cpu_base->softirq_activated = 1;
1928 raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1929 }
1930
1931 __hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1932 raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1933}
1934
1935/*
1936 * Sleep related functions:
1937 */
1938static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1939{
1940 struct hrtimer_sleeper *t =
1941 container_of(timer, struct hrtimer_sleeper, timer);
1942 struct task_struct *task = t->task;
1943
1944 t->task = NULL;
1945 if (task)
1946 wake_up_process(task);
1947
1948 return HRTIMER_NORESTART;
1949}
1950
1951/**
1952 * hrtimer_sleeper_start_expires - Start a hrtimer sleeper timer
1953 * @sl: sleeper to be started
1954 * @mode: timer mode abs/rel
1955 *
1956 * Wrapper around hrtimer_start_expires() for hrtimer_sleeper based timers
1957 * to allow PREEMPT_RT to tweak the delivery mode (soft/hardirq context)
1958 */
1959void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
1960 enum hrtimer_mode mode)
1961{
1962 /*
1963 * Make the enqueue delivery mode check work on RT. If the sleeper
1964 * was initialized for hard interrupt delivery, force the mode bit.
1965 * This is a special case for hrtimer_sleepers because
1966 * hrtimer_init_sleeper() determines the delivery mode on RT so the
1967 * fiddling with this decision is avoided at the call sites.
1968 */
1969 if (IS_ENABLED(CONFIG_PREEMPT_RT) && sl->timer.is_hard)
1970 mode |= HRTIMER_MODE_HARD;
1971
1972 hrtimer_start_expires(&sl->timer, mode);
1973}
1974EXPORT_SYMBOL_GPL(hrtimer_sleeper_start_expires);
1975
1976static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
1977 clockid_t clock_id, enum hrtimer_mode mode)
1978{
1979 /*
1980 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1981 * marked for hard interrupt expiry mode are moved into soft
1982 * interrupt context either for latency reasons or because the
1983 * hrtimer callback takes regular spinlocks or invokes other
1984 * functions which are not suitable for hard interrupt context on
1985 * PREEMPT_RT.
1986 *
1987 * The hrtimer_sleeper callback is RT compatible in hard interrupt
1988 * context, but there is a latency concern: Untrusted userspace can
1989 * spawn many threads which arm timers for the same expiry time on
1990 * the same CPU. That causes a latency spike due to the wakeup of
1991 * a gazillion threads.
1992 *
1993 * OTOH, privileged real-time user space applications rely on the
1994 * low latency of hard interrupt wakeups. If the current task is in
1995 * a real-time scheduling class, mark the mode for hard interrupt
1996 * expiry.
1997 */
1998 if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
1999 if (task_is_realtime(current) && !(mode & HRTIMER_MODE_SOFT))
2000 mode |= HRTIMER_MODE_HARD;
2001 }
2002
2003 __hrtimer_init(&sl->timer, clock_id, mode);
2004 sl->timer.function = hrtimer_wakeup;
2005 sl->task = current;
2006}
2007
2008/**
2009 * hrtimer_init_sleeper - initialize sleeper to the given clock
2010 * @sl: sleeper to be initialized
2011 * @clock_id: the clock to be used
2012 * @mode: timer mode abs/rel
2013 */
2014void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
2015 enum hrtimer_mode mode)
2016{
2017 debug_init(&sl->timer, clock_id, mode);
2018 __hrtimer_init_sleeper(sl, clock_id, mode);
2019
2020}
2021EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
2022
2023int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
2024{
2025 switch(restart->nanosleep.type) {
2026#ifdef CONFIG_COMPAT_32BIT_TIME
2027 case TT_COMPAT:
2028 if (put_old_timespec32(ts, restart->nanosleep.compat_rmtp))
2029 return -EFAULT;
2030 break;
2031#endif
2032 case TT_NATIVE:
2033 if (put_timespec64(ts, restart->nanosleep.rmtp))
2034 return -EFAULT;
2035 break;
2036 default:
2037 BUG();
2038 }
2039 return -ERESTART_RESTARTBLOCK;
2040}
2041
2042static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
2043{
2044 struct restart_block *restart;
2045
2046 do {
2047 set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2048 hrtimer_sleeper_start_expires(t, mode);
2049
2050 if (likely(t->task))
2051 schedule();
2052
2053 hrtimer_cancel(&t->timer);
2054 mode = HRTIMER_MODE_ABS;
2055
2056 } while (t->task && !signal_pending(current));
2057
2058 __set_current_state(TASK_RUNNING);
2059
2060 if (!t->task)
2061 return 0;
2062
2063 restart = ¤t->restart_block;
2064 if (restart->nanosleep.type != TT_NONE) {
2065 ktime_t rem = hrtimer_expires_remaining(&t->timer);
2066 struct timespec64 rmt;
2067
2068 if (rem <= 0)
2069 return 0;
2070 rmt = ktime_to_timespec64(rem);
2071
2072 return nanosleep_copyout(restart, &rmt);
2073 }
2074 return -ERESTART_RESTARTBLOCK;
2075}
2076
2077static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
2078{
2079 struct hrtimer_sleeper t;
2080 int ret;
2081
2082 hrtimer_init_sleeper_on_stack(&t, restart->nanosleep.clockid,
2083 HRTIMER_MODE_ABS);
2084 hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
2085 ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
2086 destroy_hrtimer_on_stack(&t.timer);
2087 return ret;
2088}
2089
2090long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
2091 const clockid_t clockid)
2092{
2093 struct restart_block *restart;
2094 struct hrtimer_sleeper t;
2095 int ret = 0;
2096 u64 slack;
2097
2098 slack = current->timer_slack_ns;
2099 if (rt_task(current))
2100 slack = 0;
2101
2102 hrtimer_init_sleeper_on_stack(&t, clockid, mode);
2103 hrtimer_set_expires_range_ns(&t.timer, rqtp, slack);
2104 ret = do_nanosleep(&t, mode);
2105 if (ret != -ERESTART_RESTARTBLOCK)
2106 goto out;
2107
2108 /* Absolute timers do not update the rmtp value and restart: */
2109 if (mode == HRTIMER_MODE_ABS) {
2110 ret = -ERESTARTNOHAND;
2111 goto out;
2112 }
2113
2114 restart = ¤t->restart_block;
2115 restart->nanosleep.clockid = t.timer.base->clockid;
2116 restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
2117 set_restart_fn(restart, hrtimer_nanosleep_restart);
2118out:
2119 destroy_hrtimer_on_stack(&t.timer);
2120 return ret;
2121}
2122
2123#ifdef CONFIG_64BIT
2124
2125SYSCALL_DEFINE2(nanosleep, struct __kernel_timespec __user *, rqtp,
2126 struct __kernel_timespec __user *, rmtp)
2127{
2128 struct timespec64 tu;
2129
2130 if (get_timespec64(&tu, rqtp))
2131 return -EFAULT;
2132
2133 if (!timespec64_valid(&tu))
2134 return -EINVAL;
2135
2136 current->restart_block.fn = do_no_restart_syscall;
2137 current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
2138 current->restart_block.nanosleep.rmtp = rmtp;
2139 return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2140 CLOCK_MONOTONIC);
2141}
2142
2143#endif
2144
2145#ifdef CONFIG_COMPAT_32BIT_TIME
2146
2147SYSCALL_DEFINE2(nanosleep_time32, struct old_timespec32 __user *, rqtp,
2148 struct old_timespec32 __user *, rmtp)
2149{
2150 struct timespec64 tu;
2151
2152 if (get_old_timespec32(&tu, rqtp))
2153 return -EFAULT;
2154
2155 if (!timespec64_valid(&tu))
2156 return -EINVAL;
2157
2158 current->restart_block.fn = do_no_restart_syscall;
2159 current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
2160 current->restart_block.nanosleep.compat_rmtp = rmtp;
2161 return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2162 CLOCK_MONOTONIC);
2163}
2164#endif
2165
2166/*
2167 * Functions related to boot-time initialization:
2168 */
2169int hrtimers_prepare_cpu(unsigned int cpu)
2170{
2171 struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
2172 int i;
2173
2174 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2175 struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i];
2176
2177 clock_b->cpu_base = cpu_base;
2178 seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock);
2179 timerqueue_init_head(&clock_b->active);
2180 }
2181
2182 cpu_base->cpu = cpu;
2183 cpu_base->active_bases = 0;
2184 cpu_base->hres_active = 0;
2185 cpu_base->hang_detected = 0;
2186 cpu_base->next_timer = NULL;
2187 cpu_base->softirq_next_timer = NULL;
2188 cpu_base->expires_next = KTIME_MAX;
2189 cpu_base->softirq_expires_next = KTIME_MAX;
2190 cpu_base->online = 1;
2191 hrtimer_cpu_base_init_expiry_lock(cpu_base);
2192 return 0;
2193}
2194
2195#ifdef CONFIG_HOTPLUG_CPU
2196
2197static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
2198 struct hrtimer_clock_base *new_base)
2199{
2200 struct hrtimer *timer;
2201 struct timerqueue_node *node;
2202
2203 while ((node = timerqueue_getnext(&old_base->active))) {
2204 timer = container_of(node, struct hrtimer, node);
2205 BUG_ON(hrtimer_callback_running(timer));
2206 debug_deactivate(timer);
2207
2208 /*
2209 * Mark it as ENQUEUED not INACTIVE otherwise the
2210 * timer could be seen as !active and just vanish away
2211 * under us on another CPU
2212 */
2213 __remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
2214 timer->base = new_base;
2215 /*
2216 * Enqueue the timers on the new cpu. This does not
2217 * reprogram the event device in case the timer
2218 * expires before the earliest on this CPU, but we run
2219 * hrtimer_interrupt after we migrated everything to
2220 * sort out already expired timers and reprogram the
2221 * event device.
2222 */
2223 enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
2224 }
2225}
2226
2227int hrtimers_cpu_dying(unsigned int dying_cpu)
2228{
2229 int i, ncpu = cpumask_any_and(cpu_active_mask, housekeeping_cpumask(HK_TYPE_TIMER));
2230 struct hrtimer_cpu_base *old_base, *new_base;
2231
2232 old_base = this_cpu_ptr(&hrtimer_bases);
2233 new_base = &per_cpu(hrtimer_bases, ncpu);
2234
2235 /*
2236 * The caller is globally serialized and nobody else
2237 * takes two locks at once, deadlock is not possible.
2238 */
2239 raw_spin_lock(&old_base->lock);
2240 raw_spin_lock_nested(&new_base->lock, SINGLE_DEPTH_NESTING);
2241
2242 for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2243 migrate_hrtimer_list(&old_base->clock_base[i],
2244 &new_base->clock_base[i]);
2245 }
2246
2247 /*
2248 * The migration might have changed the first expiring softirq
2249 * timer on this CPU. Update it.
2250 */
2251 __hrtimer_get_next_event(new_base, HRTIMER_ACTIVE_SOFT);
2252 /* Tell the other CPU to retrigger the next event */
2253 smp_call_function_single(ncpu, retrigger_next_event, NULL, 0);
2254
2255 raw_spin_unlock(&new_base->lock);
2256 old_base->online = 0;
2257 raw_spin_unlock(&old_base->lock);
2258
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) for SCHED_OTHER tasks
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 /*
2301 * Override any slack passed by the user if under
2302 * rt contraints.
2303 */
2304 if (rt_task(current))
2305 delta = 0;
2306
2307 hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
2308 hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
2309 hrtimer_sleeper_start_expires(&t, mode);
2310
2311 if (likely(t.task))
2312 schedule();
2313
2314 hrtimer_cancel(&t.timer);
2315 destroy_hrtimer_on_stack(&t.timer);
2316
2317 __set_current_state(TASK_RUNNING);
2318
2319 return !t.task ? 0 : -EINTR;
2320}
2321EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
2322
2323/**
2324 * schedule_hrtimeout_range - sleep until timeout
2325 * @expires: timeout value (ktime_t)
2326 * @delta: slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2327 * @mode: timer mode
2328 *
2329 * Make the current task sleep until the given expiry time has
2330 * elapsed. The routine will return immediately unless
2331 * the current task state has been set (see set_current_state()).
2332 *
2333 * The @delta argument gives the kernel the freedom to schedule the
2334 * actual wakeup to a time that is both power and performance friendly
2335 * for regular (non RT/DL) tasks.
2336 * The kernel give the normal best effort behavior for "@expires+@delta",
2337 * but may decide to fire the timer earlier, but no earlier than @expires.
2338 *
2339 * You can set the task state as follows -
2340 *
2341 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2342 * pass before the routine returns unless the current task is explicitly
2343 * woken up, (e.g. by wake_up_process()).
2344 *
2345 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2346 * delivered to the current task or the current task is explicitly woken
2347 * up.
2348 *
2349 * The current task state is guaranteed to be TASK_RUNNING when this
2350 * routine returns.
2351 *
2352 * Returns 0 when the timer has expired. If the task was woken before the
2353 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2354 * by an explicit wakeup, it returns -EINTR.
2355 */
2356int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
2357 const enum hrtimer_mode mode)
2358{
2359 return schedule_hrtimeout_range_clock(expires, delta, mode,
2360 CLOCK_MONOTONIC);
2361}
2362EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
2363
2364/**
2365 * schedule_hrtimeout - sleep until timeout
2366 * @expires: timeout value (ktime_t)
2367 * @mode: timer mode
2368 *
2369 * Make the current task sleep until the given expiry time has
2370 * elapsed. The routine will return immediately unless
2371 * the current task state has been set (see set_current_state()).
2372 *
2373 * You can set the task state as follows -
2374 *
2375 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2376 * pass before the routine returns unless the current task is explicitly
2377 * woken up, (e.g. by wake_up_process()).
2378 *
2379 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2380 * delivered to the current task or the current task is explicitly woken
2381 * up.
2382 *
2383 * The current task state is guaranteed to be TASK_RUNNING when this
2384 * routine returns.
2385 *
2386 * Returns 0 when the timer has expired. If the task was woken before the
2387 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2388 * by an explicit wakeup, it returns -EINTR.
2389 */
2390int __sched schedule_hrtimeout(ktime_t *expires,
2391 const enum hrtimer_mode mode)
2392{
2393 return schedule_hrtimeout_range(expires, 0, mode);
2394}
2395EXPORT_SYMBOL_GPL(schedule_hrtimeout);