xref: /openbmc/linux/kernel/time/hrtimer.c (revision 0e6774ec)
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  */
69 DEFINE_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 
117 static 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  */
138 static 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 
148 static 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  */
165 static
166 struct 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  */
194 static int
195 hrtimer_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 
203 static inline
204 struct 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  */
226 static inline struct hrtimer_clock_base *
227 switch_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);
236 again:
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 
278 static inline bool is_migration_base(struct hrtimer_clock_base *base)
279 {
280 	return false;
281 }
282 
283 static inline struct hrtimer_clock_base *
284 lock_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  */
306 s64 __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 }
324 EXPORT_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  */
330 ktime_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 
344 EXPORT_SYMBOL_GPL(ktime_add_safe);
345 
346 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
347 
348 static const struct debug_obj_descr hrtimer_debug_descr;
349 
350 static 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  */
359 static 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  */
378 static 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  */
393 static 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 
407 static 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 
415 static inline void debug_hrtimer_init(struct hrtimer *timer)
416 {
417 	debug_object_init(timer, &hrtimer_debug_descr);
418 }
419 
420 static inline void debug_hrtimer_activate(struct hrtimer *timer,
421 					  enum hrtimer_mode mode)
422 {
423 	debug_object_activate(timer, &hrtimer_debug_descr);
424 }
425 
426 static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
427 {
428 	debug_object_deactivate(timer, &hrtimer_debug_descr);
429 }
430 
431 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
432 			   enum hrtimer_mode mode);
433 
434 void 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 }
440 EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
441 
442 static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
443 				   clockid_t clock_id, enum hrtimer_mode mode);
444 
445 void 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 }
451 EXPORT_SYMBOL_GPL(hrtimer_init_sleeper_on_stack);
452 
453 void destroy_hrtimer_on_stack(struct hrtimer *timer)
454 {
455 	debug_object_free(timer, &hrtimer_debug_descr);
456 }
457 EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
458 
459 #else
460 
461 static inline void debug_hrtimer_init(struct hrtimer *timer) { }
462 static inline void debug_hrtimer_activate(struct hrtimer *timer,
463 					  enum hrtimer_mode mode) { }
464 static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
465 #endif
466 
467 static inline void
468 debug_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 
475 static 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 
482 static inline void debug_deactivate(struct hrtimer *timer)
483 {
484 	debug_hrtimer_deactivate(timer);
485 	trace_hrtimer_cancel(timer);
486 }
487 
488 static 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 
505 static 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  */
571 static 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 
597 static 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 
628 static 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  */
647 static 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 
653 static inline int hrtimer_hres_active(void)
654 {
655 	return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
656 }
657 
658 static 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  */
692 static void
693 hrtimer_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  */
711 static bool hrtimer_hres_enabled __read_mostly  = true;
712 unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
713 EXPORT_SYMBOL_GPL(hrtimer_resolution);
714 
715 /*
716  * Enable / Disable high resolution mode
717  */
718 static 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  */
728 static inline int hrtimer_is_hres_enabled(void)
729 {
730 	return hrtimer_hres_enabled;
731 }
732 
733 static void retrigger_next_event(void *arg);
734 
735 /*
736  * Switch to high resolution mode
737  */
738 static 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();
751 	/* "Retrigger" the interrupt to get things going */
752 	retrigger_next_event(NULL);
753 }
754 
755 #else
756 
757 static inline int hrtimer_is_hres_enabled(void) { return 0; }
758 static 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  */
774 static 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  */
811 static 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 
872 static 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  */
948 void 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 
982 out_timerfd:
983 	timerfd_clock_was_set();
984 }
985 
986 static void clock_was_set_work(struct work_struct *work)
987 {
988 	clock_was_set(CLOCK_SET_WALL);
989 }
990 
991 static 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  */
997 void 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  */
1007 void 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  */
1017 static inline
1018 void 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  * Returns the number of overruns.
1032  *
1033  * Can be safely called from the callback function of @timer. If
1034  * called from other contexts @timer must neither be enqueued nor
1035  * running the callback and the caller needs to take care of
1036  * serialization.
1037  *
1038  * Note: This only updates the timer expiry value and does not requeue
1039  * the timer.
1040  */
1041 u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
1042 {
1043 	u64 orun = 1;
1044 	ktime_t delta;
1045 
1046 	delta = ktime_sub(now, hrtimer_get_expires(timer));
1047 
1048 	if (delta < 0)
1049 		return 0;
1050 
1051 	if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
1052 		return 0;
1053 
1054 	if (interval < hrtimer_resolution)
1055 		interval = hrtimer_resolution;
1056 
1057 	if (unlikely(delta >= interval)) {
1058 		s64 incr = ktime_to_ns(interval);
1059 
1060 		orun = ktime_divns(delta, incr);
1061 		hrtimer_add_expires_ns(timer, incr * orun);
1062 		if (hrtimer_get_expires_tv64(timer) > now)
1063 			return orun;
1064 		/*
1065 		 * This (and the ktime_add() below) is the
1066 		 * correction for exact:
1067 		 */
1068 		orun++;
1069 	}
1070 	hrtimer_add_expires(timer, interval);
1071 
1072 	return orun;
1073 }
1074 EXPORT_SYMBOL_GPL(hrtimer_forward);
1075 
1076 /*
1077  * enqueue_hrtimer - internal function to (re)start a timer
1078  *
1079  * The timer is inserted in expiry order. Insertion into the
1080  * red black tree is O(log(n)). Must hold the base lock.
1081  *
1082  * Returns 1 when the new timer is the leftmost timer in the tree.
1083  */
1084 static int enqueue_hrtimer(struct hrtimer *timer,
1085 			   struct hrtimer_clock_base *base,
1086 			   enum hrtimer_mode mode)
1087 {
1088 	debug_activate(timer, mode);
1089 	WARN_ON_ONCE(!base->cpu_base->online);
1090 
1091 	base->cpu_base->active_bases |= 1 << base->index;
1092 
1093 	/* Pairs with the lockless read in hrtimer_is_queued() */
1094 	WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
1095 
1096 	return timerqueue_add(&base->active, &timer->node);
1097 }
1098 
1099 /*
1100  * __remove_hrtimer - internal function to remove a timer
1101  *
1102  * Caller must hold the base lock.
1103  *
1104  * High resolution timer mode reprograms the clock event device when the
1105  * timer is the one which expires next. The caller can disable this by setting
1106  * reprogram to zero. This is useful, when the context does a reprogramming
1107  * anyway (e.g. timer interrupt)
1108  */
1109 static void __remove_hrtimer(struct hrtimer *timer,
1110 			     struct hrtimer_clock_base *base,
1111 			     u8 newstate, int reprogram)
1112 {
1113 	struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1114 	u8 state = timer->state;
1115 
1116 	/* Pairs with the lockless read in hrtimer_is_queued() */
1117 	WRITE_ONCE(timer->state, newstate);
1118 	if (!(state & HRTIMER_STATE_ENQUEUED))
1119 		return;
1120 
1121 	if (!timerqueue_del(&base->active, &timer->node))
1122 		cpu_base->active_bases &= ~(1 << base->index);
1123 
1124 	/*
1125 	 * Note: If reprogram is false we do not update
1126 	 * cpu_base->next_timer. This happens when we remove the first
1127 	 * timer on a remote cpu. No harm as we never dereference
1128 	 * cpu_base->next_timer. So the worst thing what can happen is
1129 	 * an superfluous call to hrtimer_force_reprogram() on the
1130 	 * remote cpu later on if the same timer gets enqueued again.
1131 	 */
1132 	if (reprogram && timer == cpu_base->next_timer)
1133 		hrtimer_force_reprogram(cpu_base, 1);
1134 }
1135 
1136 /*
1137  * remove hrtimer, called with base lock held
1138  */
1139 static inline int
1140 remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base,
1141 	       bool restart, bool keep_local)
1142 {
1143 	u8 state = timer->state;
1144 
1145 	if (state & HRTIMER_STATE_ENQUEUED) {
1146 		bool reprogram;
1147 
1148 		/*
1149 		 * Remove the timer and force reprogramming when high
1150 		 * resolution mode is active and the timer is on the current
1151 		 * CPU. If we remove a timer on another CPU, reprogramming is
1152 		 * skipped. The interrupt event on this CPU is fired and
1153 		 * reprogramming happens in the interrupt handler. This is a
1154 		 * rare case and less expensive than a smp call.
1155 		 */
1156 		debug_deactivate(timer);
1157 		reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1158 
1159 		/*
1160 		 * If the timer is not restarted then reprogramming is
1161 		 * required if the timer is local. If it is local and about
1162 		 * to be restarted, avoid programming it twice (on removal
1163 		 * and a moment later when it's requeued).
1164 		 */
1165 		if (!restart)
1166 			state = HRTIMER_STATE_INACTIVE;
1167 		else
1168 			reprogram &= !keep_local;
1169 
1170 		__remove_hrtimer(timer, base, state, reprogram);
1171 		return 1;
1172 	}
1173 	return 0;
1174 }
1175 
1176 static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
1177 					    const enum hrtimer_mode mode)
1178 {
1179 #ifdef CONFIG_TIME_LOW_RES
1180 	/*
1181 	 * CONFIG_TIME_LOW_RES indicates that the system has no way to return
1182 	 * granular time values. For relative timers we add hrtimer_resolution
1183 	 * (i.e. one jiffie) to prevent short timeouts.
1184 	 */
1185 	timer->is_rel = mode & HRTIMER_MODE_REL;
1186 	if (timer->is_rel)
1187 		tim = ktime_add_safe(tim, hrtimer_resolution);
1188 #endif
1189 	return tim;
1190 }
1191 
1192 static void
1193 hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
1194 {
1195 	ktime_t expires;
1196 
1197 	/*
1198 	 * Find the next SOFT expiration.
1199 	 */
1200 	expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
1201 
1202 	/*
1203 	 * reprogramming needs to be triggered, even if the next soft
1204 	 * hrtimer expires at the same time than the next hard
1205 	 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
1206 	 */
1207 	if (expires == KTIME_MAX)
1208 		return;
1209 
1210 	/*
1211 	 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
1212 	 * cpu_base->*expires_next is only set by hrtimer_reprogram()
1213 	 */
1214 	hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
1215 }
1216 
1217 static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1218 				    u64 delta_ns, const enum hrtimer_mode mode,
1219 				    struct hrtimer_clock_base *base)
1220 {
1221 	struct hrtimer_clock_base *new_base;
1222 	bool force_local, first;
1223 
1224 	/*
1225 	 * If the timer is on the local cpu base and is the first expiring
1226 	 * timer then this might end up reprogramming the hardware twice
1227 	 * (on removal and on enqueue). To avoid that by prevent the
1228 	 * reprogram on removal, keep the timer local to the current CPU
1229 	 * and enforce reprogramming after it is queued no matter whether
1230 	 * it is the new first expiring timer again or not.
1231 	 */
1232 	force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1233 	force_local &= base->cpu_base->next_timer == timer;
1234 
1235 	/*
1236 	 * Remove an active timer from the queue. In case it is not queued
1237 	 * on the current CPU, make sure that remove_hrtimer() updates the
1238 	 * remote data correctly.
1239 	 *
1240 	 * If it's on the current CPU and the first expiring timer, then
1241 	 * skip reprogramming, keep the timer local and enforce
1242 	 * reprogramming later if it was the first expiring timer.  This
1243 	 * avoids programming the underlying clock event twice (once at
1244 	 * removal and once after enqueue).
1245 	 */
1246 	remove_hrtimer(timer, base, true, force_local);
1247 
1248 	if (mode & HRTIMER_MODE_REL)
1249 		tim = ktime_add_safe(tim, base->get_time());
1250 
1251 	tim = hrtimer_update_lowres(timer, tim, mode);
1252 
1253 	hrtimer_set_expires_range_ns(timer, tim, delta_ns);
1254 
1255 	/* Switch the timer base, if necessary: */
1256 	if (!force_local) {
1257 		new_base = switch_hrtimer_base(timer, base,
1258 					       mode & HRTIMER_MODE_PINNED);
1259 	} else {
1260 		new_base = base;
1261 	}
1262 
1263 	first = enqueue_hrtimer(timer, new_base, mode);
1264 	if (!force_local)
1265 		return first;
1266 
1267 	/*
1268 	 * Timer was forced to stay on the current CPU to avoid
1269 	 * reprogramming on removal and enqueue. Force reprogram the
1270 	 * hardware by evaluating the new first expiring timer.
1271 	 */
1272 	hrtimer_force_reprogram(new_base->cpu_base, 1);
1273 	return 0;
1274 }
1275 
1276 /**
1277  * hrtimer_start_range_ns - (re)start an hrtimer
1278  * @timer:	the timer to be added
1279  * @tim:	expiry time
1280  * @delta_ns:	"slack" range for the timer
1281  * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
1282  *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
1283  *		softirq based mode is considered for debug purpose only!
1284  */
1285 void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1286 			    u64 delta_ns, const enum hrtimer_mode mode)
1287 {
1288 	struct hrtimer_clock_base *base;
1289 	unsigned long flags;
1290 
1291 	if (WARN_ON_ONCE(!timer->function))
1292 		return;
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 }
1310 EXPORT_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  */
1323 int 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 }
1348 EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1349 
1350 #ifdef CONFIG_PREEMPT_RT
1351 static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
1352 {
1353 	spin_lock_init(&base->softirq_expiry_lock);
1354 }
1355 
1356 static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
1357 {
1358 	spin_lock(&base->softirq_expiry_lock);
1359 }
1360 
1361 static 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  */
1373 static 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  */
1400 void 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
1427 static inline void
1428 hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
1429 static inline void
1430 hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
1431 static inline void
1432 hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
1433 static 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  */
1445 int 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 }
1457 EXPORT_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  */
1464 ktime_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 }
1478 EXPORT_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  */
1486 u64 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  */
1509 u64 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 
1536 static 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 
1548 static 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  */
1596 void 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 }
1602 EXPORT_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  */
1611 bool 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 }
1629 EXPORT_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 
1649 static 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 
1724 static 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 
1763 static __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  */
1788 void 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);
1801 retry:
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 */
1880 static 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 
1894 static 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  */
1901 void 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  */
1938 static 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  */
1959 void 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 }
1974 EXPORT_SYMBOL_GPL(hrtimer_sleeper_start_expires);
1975 
1976 static 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  */
2014 void 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 }
2021 EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
2022 
2023 int 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 
2042 static 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 = &current->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 
2077 static 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 
2090 long 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 = &current->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);
2118 out:
2119 	destroy_hrtimer_on_stack(&t.timer);
2120 	return ret;
2121 }
2122 
2123 #ifdef CONFIG_64BIT
2124 
2125 SYSCALL_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 
2147 SYSCALL_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  */
2169 int 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 
2197 static 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 
2227 int 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 	tick_cancel_sched_timer(dying_cpu);
2233 
2234 	old_base = this_cpu_ptr(&hrtimer_bases);
2235 	new_base = &per_cpu(hrtimer_bases, ncpu);
2236 
2237 	/*
2238 	 * The caller is globally serialized and nobody else
2239 	 * takes two locks at once, deadlock is not possible.
2240 	 */
2241 	raw_spin_lock(&old_base->lock);
2242 	raw_spin_lock_nested(&new_base->lock, SINGLE_DEPTH_NESTING);
2243 
2244 	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2245 		migrate_hrtimer_list(&old_base->clock_base[i],
2246 				     &new_base->clock_base[i]);
2247 	}
2248 
2249 	/*
2250 	 * The migration might have changed the first expiring softirq
2251 	 * timer on this CPU. Update it.
2252 	 */
2253 	__hrtimer_get_next_event(new_base, HRTIMER_ACTIVE_SOFT);
2254 	/* Tell the other CPU to retrigger the next event */
2255 	smp_call_function_single(ncpu, retrigger_next_event, NULL, 0);
2256 
2257 	raw_spin_unlock(&new_base->lock);
2258 	old_base->online = 0;
2259 	raw_spin_unlock(&old_base->lock);
2260 
2261 	return 0;
2262 }
2263 
2264 #endif /* CONFIG_HOTPLUG_CPU */
2265 
2266 void __init hrtimers_init(void)
2267 {
2268 	hrtimers_prepare_cpu(smp_processor_id());
2269 	open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
2270 }
2271 
2272 /**
2273  * schedule_hrtimeout_range_clock - sleep until timeout
2274  * @expires:	timeout value (ktime_t)
2275  * @delta:	slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2276  * @mode:	timer mode
2277  * @clock_id:	timer clock to be used
2278  */
2279 int __sched
2280 schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
2281 			       const enum hrtimer_mode mode, clockid_t clock_id)
2282 {
2283 	struct hrtimer_sleeper t;
2284 
2285 	/*
2286 	 * Optimize when a zero timeout value is given. It does not
2287 	 * matter whether this is an absolute or a relative time.
2288 	 */
2289 	if (expires && *expires == 0) {
2290 		__set_current_state(TASK_RUNNING);
2291 		return 0;
2292 	}
2293 
2294 	/*
2295 	 * A NULL parameter means "infinite"
2296 	 */
2297 	if (!expires) {
2298 		schedule();
2299 		return -EINTR;
2300 	}
2301 
2302 	/*
2303 	 * Override any slack passed by the user if under
2304 	 * rt contraints.
2305 	 */
2306 	if (rt_task(current))
2307 		delta = 0;
2308 
2309 	hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
2310 	hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
2311 	hrtimer_sleeper_start_expires(&t, mode);
2312 
2313 	if (likely(t.task))
2314 		schedule();
2315 
2316 	hrtimer_cancel(&t.timer);
2317 	destroy_hrtimer_on_stack(&t.timer);
2318 
2319 	__set_current_state(TASK_RUNNING);
2320 
2321 	return !t.task ? 0 : -EINTR;
2322 }
2323 EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
2324 
2325 /**
2326  * schedule_hrtimeout_range - sleep until timeout
2327  * @expires:	timeout value (ktime_t)
2328  * @delta:	slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2329  * @mode:	timer mode
2330  *
2331  * Make the current task sleep until the given expiry time has
2332  * elapsed. The routine will return immediately unless
2333  * the current task state has been set (see set_current_state()).
2334  *
2335  * The @delta argument gives the kernel the freedom to schedule the
2336  * actual wakeup to a time that is both power and performance friendly
2337  * for regular (non RT/DL) tasks.
2338  * The kernel give the normal best effort behavior for "@expires+@delta",
2339  * but may decide to fire the timer earlier, but no earlier than @expires.
2340  *
2341  * You can set the task state as follows -
2342  *
2343  * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2344  * pass before the routine returns unless the current task is explicitly
2345  * woken up, (e.g. by wake_up_process()).
2346  *
2347  * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2348  * delivered to the current task or the current task is explicitly woken
2349  * up.
2350  *
2351  * The current task state is guaranteed to be TASK_RUNNING when this
2352  * routine returns.
2353  *
2354  * Returns 0 when the timer has expired. If the task was woken before the
2355  * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2356  * by an explicit wakeup, it returns -EINTR.
2357  */
2358 int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
2359 				     const enum hrtimer_mode mode)
2360 {
2361 	return schedule_hrtimeout_range_clock(expires, delta, mode,
2362 					      CLOCK_MONOTONIC);
2363 }
2364 EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
2365 
2366 /**
2367  * schedule_hrtimeout - sleep until timeout
2368  * @expires:	timeout value (ktime_t)
2369  * @mode:	timer mode
2370  *
2371  * Make the current task sleep until the given expiry time has
2372  * elapsed. The routine will return immediately unless
2373  * the current task state has been set (see set_current_state()).
2374  *
2375  * You can set the task state as follows -
2376  *
2377  * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2378  * pass before the routine returns unless the current task is explicitly
2379  * woken up, (e.g. by wake_up_process()).
2380  *
2381  * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2382  * delivered to the current task or the current task is explicitly woken
2383  * up.
2384  *
2385  * The current task state is guaranteed to be TASK_RUNNING when this
2386  * routine returns.
2387  *
2388  * Returns 0 when the timer has expired. If the task was woken before the
2389  * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2390  * by an explicit wakeup, it returns -EINTR.
2391  */
2392 int __sched schedule_hrtimeout(ktime_t *expires,
2393 			       const enum hrtimer_mode mode)
2394 {
2395 	return schedule_hrtimeout_range(expires, 0, mode);
2396 }
2397 EXPORT_SYMBOL_GPL(schedule_hrtimeout);
2398