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/timer.h>
42 #include <linux/freezer.h>
43 #include <linux/compat.h>
44 
45 #include <linux/uaccess.h>
46 
47 #include <trace/events/timer.h>
48 
49 #include "tick-internal.h"
50 
51 /*
52  * Masks for selecting the soft and hard context timers from
53  * cpu_base->active
54  */
55 #define MASK_SHIFT		(HRTIMER_BASE_MONOTONIC_SOFT)
56 #define HRTIMER_ACTIVE_HARD	((1U << MASK_SHIFT) - 1)
57 #define HRTIMER_ACTIVE_SOFT	(HRTIMER_ACTIVE_HARD << MASK_SHIFT)
58 #define HRTIMER_ACTIVE_ALL	(HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD)
59 
60 /*
61  * The timer bases:
62  *
63  * There are more clockids than hrtimer bases. Thus, we index
64  * into the timer bases by the hrtimer_base_type enum. When trying
65  * to reach a base using a clockid, hrtimer_clockid_to_base()
66  * is used to convert from clockid to the proper hrtimer_base_type.
67  */
68 DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
69 {
70 	.lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
71 	.clock_base =
72 	{
73 		{
74 			.index = HRTIMER_BASE_MONOTONIC,
75 			.clockid = CLOCK_MONOTONIC,
76 			.get_time = &ktime_get,
77 		},
78 		{
79 			.index = HRTIMER_BASE_REALTIME,
80 			.clockid = CLOCK_REALTIME,
81 			.get_time = &ktime_get_real,
82 		},
83 		{
84 			.index = HRTIMER_BASE_BOOTTIME,
85 			.clockid = CLOCK_BOOTTIME,
86 			.get_time = &ktime_get_boottime,
87 		},
88 		{
89 			.index = HRTIMER_BASE_TAI,
90 			.clockid = CLOCK_TAI,
91 			.get_time = &ktime_get_clocktai,
92 		},
93 		{
94 			.index = HRTIMER_BASE_MONOTONIC_SOFT,
95 			.clockid = CLOCK_MONOTONIC,
96 			.get_time = &ktime_get,
97 		},
98 		{
99 			.index = HRTIMER_BASE_REALTIME_SOFT,
100 			.clockid = CLOCK_REALTIME,
101 			.get_time = &ktime_get_real,
102 		},
103 		{
104 			.index = HRTIMER_BASE_BOOTTIME_SOFT,
105 			.clockid = CLOCK_BOOTTIME,
106 			.get_time = &ktime_get_boottime,
107 		},
108 		{
109 			.index = HRTIMER_BASE_TAI_SOFT,
110 			.clockid = CLOCK_TAI,
111 			.get_time = &ktime_get_clocktai,
112 		},
113 	}
114 };
115 
116 static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
117 	/* Make sure we catch unsupported clockids */
118 	[0 ... MAX_CLOCKS - 1]	= HRTIMER_MAX_CLOCK_BASES,
119 
120 	[CLOCK_REALTIME]	= HRTIMER_BASE_REALTIME,
121 	[CLOCK_MONOTONIC]	= HRTIMER_BASE_MONOTONIC,
122 	[CLOCK_BOOTTIME]	= HRTIMER_BASE_BOOTTIME,
123 	[CLOCK_TAI]		= HRTIMER_BASE_TAI,
124 };
125 
126 /*
127  * Functions and macros which are different for UP/SMP systems are kept in a
128  * single place
129  */
130 #ifdef CONFIG_SMP
131 
132 /*
133  * We require the migration_base for lock_hrtimer_base()/switch_hrtimer_base()
134  * such that hrtimer_callback_running() can unconditionally dereference
135  * timer->base->cpu_base
136  */
137 static struct hrtimer_cpu_base migration_cpu_base = {
138 	.clock_base = { {
139 		.cpu_base = &migration_cpu_base,
140 		.seq      = SEQCNT_RAW_SPINLOCK_ZERO(migration_cpu_base.seq,
141 						     &migration_cpu_base.lock),
142 	}, },
143 };
144 
145 #define migration_base	migration_cpu_base.clock_base[0]
146 
is_migration_base(struct hrtimer_clock_base * base)147 static inline bool is_migration_base(struct hrtimer_clock_base *base)
148 {
149 	return base == &migration_base;
150 }
151 
152 /*
153  * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
154  * means that all timers which are tied to this base via timer->base are
155  * locked, and the base itself is locked too.
156  *
157  * So __run_timers/migrate_timers can safely modify all timers which could
158  * be found on the lists/queues.
159  *
160  * When the timer's base is locked, and the timer removed from list, it is
161  * possible to set timer->base = &migration_base and drop the lock: the timer
162  * remains locked.
163  */
164 static
lock_hrtimer_base(const struct hrtimer * timer,unsigned long * flags)165 struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
166 					     unsigned long *flags)
167 {
168 	struct hrtimer_clock_base *base;
169 
170 	for (;;) {
171 		base = READ_ONCE(timer->base);
172 		if (likely(base != &migration_base)) {
173 			raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
174 			if (likely(base == timer->base))
175 				return base;
176 			/* The timer has migrated to another CPU: */
177 			raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
178 		}
179 		cpu_relax();
180 	}
181 }
182 
183 /*
184  * We do not migrate the timer when it is expiring before the next
185  * event on the target cpu. When high resolution is enabled, we cannot
186  * reprogram the target cpu hardware and we would cause it to fire
187  * late. To keep it simple, we handle the high resolution enabled and
188  * disabled case similar.
189  *
190  * Called with cpu_base->lock of target cpu held.
191  */
192 static int
hrtimer_check_target(struct hrtimer * timer,struct hrtimer_clock_base * new_base)193 hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
194 {
195 	ktime_t expires;
196 
197 	expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
198 	return expires < new_base->cpu_base->expires_next;
199 }
200 
201 static inline
get_target_base(struct hrtimer_cpu_base * base,int pinned)202 struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
203 					 int pinned)
204 {
205 #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
206 	if (static_branch_likely(&timers_migration_enabled) && !pinned)
207 		return &per_cpu(hrtimer_bases, get_nohz_timer_target());
208 #endif
209 	return base;
210 }
211 
212 /*
213  * We switch the timer base to a power-optimized selected CPU target,
214  * if:
215  *	- NO_HZ_COMMON is enabled
216  *	- timer migration is enabled
217  *	- the timer callback is not running
218  *	- the timer is not the first expiring timer on the new target
219  *
220  * If one of the above requirements is not fulfilled we move the timer
221  * to the current CPU or leave it on the previously assigned CPU if
222  * the timer callback is currently running.
223  */
224 static inline struct hrtimer_clock_base *
switch_hrtimer_base(struct hrtimer * timer,struct hrtimer_clock_base * base,int pinned)225 switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
226 		    int pinned)
227 {
228 	struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
229 	struct hrtimer_clock_base *new_base;
230 	int basenum = base->index;
231 
232 	this_cpu_base = this_cpu_ptr(&hrtimer_bases);
233 	new_cpu_base = get_target_base(this_cpu_base, pinned);
234 again:
235 	new_base = &new_cpu_base->clock_base[basenum];
236 
237 	if (base != new_base) {
238 		/*
239 		 * We are trying to move timer to new_base.
240 		 * However we can't change timer's base while it is running,
241 		 * so we keep it on the same CPU. No hassle vs. reprogramming
242 		 * the event source in the high resolution case. The softirq
243 		 * code will take care of this when the timer function has
244 		 * completed. There is no conflict as we hold the lock until
245 		 * the timer is enqueued.
246 		 */
247 		if (unlikely(hrtimer_callback_running(timer)))
248 			return base;
249 
250 		/* See the comment in lock_hrtimer_base() */
251 		WRITE_ONCE(timer->base, &migration_base);
252 		raw_spin_unlock(&base->cpu_base->lock);
253 		raw_spin_lock(&new_base->cpu_base->lock);
254 
255 		if (new_cpu_base != this_cpu_base &&
256 		    hrtimer_check_target(timer, new_base)) {
257 			raw_spin_unlock(&new_base->cpu_base->lock);
258 			raw_spin_lock(&base->cpu_base->lock);
259 			new_cpu_base = this_cpu_base;
260 			WRITE_ONCE(timer->base, base);
261 			goto again;
262 		}
263 		WRITE_ONCE(timer->base, new_base);
264 	} else {
265 		if (new_cpu_base != this_cpu_base &&
266 		    hrtimer_check_target(timer, new_base)) {
267 			new_cpu_base = this_cpu_base;
268 			goto again;
269 		}
270 	}
271 	return new_base;
272 }
273 
274 #else /* CONFIG_SMP */
275 
is_migration_base(struct hrtimer_clock_base * base)276 static inline bool is_migration_base(struct hrtimer_clock_base *base)
277 {
278 	return false;
279 }
280 
281 static inline struct hrtimer_clock_base *
lock_hrtimer_base(const struct hrtimer * timer,unsigned long * flags)282 lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
283 {
284 	struct hrtimer_clock_base *base = timer->base;
285 
286 	raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
287 
288 	return base;
289 }
290 
291 # define switch_hrtimer_base(t, b, p)	(b)
292 
293 #endif	/* !CONFIG_SMP */
294 
295 /*
296  * Functions for the union type storage format of ktime_t which are
297  * too large for inlining:
298  */
299 #if BITS_PER_LONG < 64
300 /*
301  * Divide a ktime value by a nanosecond value
302  */
__ktime_divns(const ktime_t kt,s64 div)303 s64 __ktime_divns(const ktime_t kt, s64 div)
304 {
305 	int sft = 0;
306 	s64 dclc;
307 	u64 tmp;
308 
309 	dclc = ktime_to_ns(kt);
310 	tmp = dclc < 0 ? -dclc : dclc;
311 
312 	/* Make sure the divisor is less than 2^32: */
313 	while (div >> 32) {
314 		sft++;
315 		div >>= 1;
316 	}
317 	tmp >>= sft;
318 	do_div(tmp, (u32) div);
319 	return dclc < 0 ? -tmp : tmp;
320 }
321 EXPORT_SYMBOL_GPL(__ktime_divns);
322 #endif /* BITS_PER_LONG >= 64 */
323 
324 /*
325  * Add two ktime values and do a safety check for overflow:
326  */
ktime_add_safe(const ktime_t lhs,const ktime_t rhs)327 ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
328 {
329 	ktime_t res = ktime_add_unsafe(lhs, rhs);
330 
331 	/*
332 	 * We use KTIME_SEC_MAX here, the maximum timeout which we can
333 	 * return to user space in a timespec:
334 	 */
335 	if (res < 0 || res < lhs || res < rhs)
336 		res = ktime_set(KTIME_SEC_MAX, 0);
337 
338 	return res;
339 }
340 
341 EXPORT_SYMBOL_GPL(ktime_add_safe);
342 
343 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
344 
345 static const struct debug_obj_descr hrtimer_debug_descr;
346 
hrtimer_debug_hint(void * addr)347 static void *hrtimer_debug_hint(void *addr)
348 {
349 	return ((struct hrtimer *) addr)->function;
350 }
351 
352 /*
353  * fixup_init is called when:
354  * - an active object is initialized
355  */
hrtimer_fixup_init(void * addr,enum debug_obj_state state)356 static bool hrtimer_fixup_init(void *addr, enum debug_obj_state state)
357 {
358 	struct hrtimer *timer = addr;
359 
360 	switch (state) {
361 	case ODEBUG_STATE_ACTIVE:
362 		hrtimer_cancel(timer);
363 		debug_object_init(timer, &hrtimer_debug_descr);
364 		return true;
365 	default:
366 		return false;
367 	}
368 }
369 
370 /*
371  * fixup_activate is called when:
372  * - an active object is activated
373  * - an unknown non-static object is activated
374  */
hrtimer_fixup_activate(void * addr,enum debug_obj_state state)375 static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
376 {
377 	switch (state) {
378 	case ODEBUG_STATE_ACTIVE:
379 		WARN_ON(1);
380 		fallthrough;
381 	default:
382 		return false;
383 	}
384 }
385 
386 /*
387  * fixup_free is called when:
388  * - an active object is freed
389  */
hrtimer_fixup_free(void * addr,enum debug_obj_state state)390 static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state)
391 {
392 	struct hrtimer *timer = addr;
393 
394 	switch (state) {
395 	case ODEBUG_STATE_ACTIVE:
396 		hrtimer_cancel(timer);
397 		debug_object_free(timer, &hrtimer_debug_descr);
398 		return true;
399 	default:
400 		return false;
401 	}
402 }
403 
404 static const struct debug_obj_descr hrtimer_debug_descr = {
405 	.name		= "hrtimer",
406 	.debug_hint	= hrtimer_debug_hint,
407 	.fixup_init	= hrtimer_fixup_init,
408 	.fixup_activate	= hrtimer_fixup_activate,
409 	.fixup_free	= hrtimer_fixup_free,
410 };
411 
debug_hrtimer_init(struct hrtimer * timer)412 static inline void debug_hrtimer_init(struct hrtimer *timer)
413 {
414 	debug_object_init(timer, &hrtimer_debug_descr);
415 }
416 
debug_hrtimer_activate(struct hrtimer * timer,enum hrtimer_mode mode)417 static inline void debug_hrtimer_activate(struct hrtimer *timer,
418 					  enum hrtimer_mode mode)
419 {
420 	debug_object_activate(timer, &hrtimer_debug_descr);
421 }
422 
debug_hrtimer_deactivate(struct hrtimer * timer)423 static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
424 {
425 	debug_object_deactivate(timer, &hrtimer_debug_descr);
426 }
427 
428 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
429 			   enum hrtimer_mode mode);
430 
hrtimer_init_on_stack(struct hrtimer * timer,clockid_t clock_id,enum hrtimer_mode mode)431 void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
432 			   enum hrtimer_mode mode)
433 {
434 	debug_object_init_on_stack(timer, &hrtimer_debug_descr);
435 	__hrtimer_init(timer, clock_id, mode);
436 }
437 EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
438 
439 static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
440 				   clockid_t clock_id, enum hrtimer_mode mode);
441 
hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper * sl,clockid_t clock_id,enum hrtimer_mode mode)442 void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
443 				   clockid_t clock_id, enum hrtimer_mode mode)
444 {
445 	debug_object_init_on_stack(&sl->timer, &hrtimer_debug_descr);
446 	__hrtimer_init_sleeper(sl, clock_id, mode);
447 }
448 EXPORT_SYMBOL_GPL(hrtimer_init_sleeper_on_stack);
449 
destroy_hrtimer_on_stack(struct hrtimer * timer)450 void destroy_hrtimer_on_stack(struct hrtimer *timer)
451 {
452 	debug_object_free(timer, &hrtimer_debug_descr);
453 }
454 EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
455 
456 #else
457 
debug_hrtimer_init(struct hrtimer * timer)458 static inline void debug_hrtimer_init(struct hrtimer *timer) { }
debug_hrtimer_activate(struct hrtimer * timer,enum hrtimer_mode mode)459 static inline void debug_hrtimer_activate(struct hrtimer *timer,
460 					  enum hrtimer_mode mode) { }
debug_hrtimer_deactivate(struct hrtimer * timer)461 static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
462 #endif
463 
464 static inline void
debug_init(struct hrtimer * timer,clockid_t clockid,enum hrtimer_mode mode)465 debug_init(struct hrtimer *timer, clockid_t clockid,
466 	   enum hrtimer_mode mode)
467 {
468 	debug_hrtimer_init(timer);
469 	trace_hrtimer_init(timer, clockid, mode);
470 }
471 
debug_activate(struct hrtimer * timer,enum hrtimer_mode mode)472 static inline void debug_activate(struct hrtimer *timer,
473 				  enum hrtimer_mode mode)
474 {
475 	debug_hrtimer_activate(timer, mode);
476 	trace_hrtimer_start(timer, mode);
477 }
478 
debug_deactivate(struct hrtimer * timer)479 static inline void debug_deactivate(struct hrtimer *timer)
480 {
481 	debug_hrtimer_deactivate(timer);
482 	trace_hrtimer_cancel(timer);
483 }
484 
485 static struct hrtimer_clock_base *
__next_base(struct hrtimer_cpu_base * cpu_base,unsigned int * active)486 __next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
487 {
488 	unsigned int idx;
489 
490 	if (!*active)
491 		return NULL;
492 
493 	idx = __ffs(*active);
494 	*active &= ~(1U << idx);
495 
496 	return &cpu_base->clock_base[idx];
497 }
498 
499 #define for_each_active_base(base, cpu_base, active)	\
500 	while ((base = __next_base((cpu_base), &(active))))
501 
__hrtimer_next_event_base(struct hrtimer_cpu_base * cpu_base,const struct hrtimer * exclude,unsigned int active,ktime_t expires_next)502 static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
503 					 const struct hrtimer *exclude,
504 					 unsigned int active,
505 					 ktime_t expires_next)
506 {
507 	struct hrtimer_clock_base *base;
508 	ktime_t expires;
509 
510 	for_each_active_base(base, cpu_base, active) {
511 		struct timerqueue_node *next;
512 		struct hrtimer *timer;
513 
514 		next = timerqueue_getnext(&base->active);
515 		timer = container_of(next, struct hrtimer, node);
516 		if (timer == exclude) {
517 			/* Get to the next timer in the queue. */
518 			next = timerqueue_iterate_next(next);
519 			if (!next)
520 				continue;
521 
522 			timer = container_of(next, struct hrtimer, node);
523 		}
524 		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
525 		if (expires < expires_next) {
526 			expires_next = expires;
527 
528 			/* Skip cpu_base update if a timer is being excluded. */
529 			if (exclude)
530 				continue;
531 
532 			if (timer->is_soft)
533 				cpu_base->softirq_next_timer = timer;
534 			else
535 				cpu_base->next_timer = timer;
536 		}
537 	}
538 	/*
539 	 * clock_was_set() might have changed base->offset of any of
540 	 * the clock bases so the result might be negative. Fix it up
541 	 * to prevent a false positive in clockevents_program_event().
542 	 */
543 	if (expires_next < 0)
544 		expires_next = 0;
545 	return expires_next;
546 }
547 
548 /*
549  * Recomputes cpu_base::*next_timer and returns the earliest expires_next
550  * but does not set cpu_base::*expires_next, that is done by
551  * hrtimer[_force]_reprogram and hrtimer_interrupt only. When updating
552  * cpu_base::*expires_next right away, reprogramming logic would no longer
553  * work.
554  *
555  * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
556  * those timers will get run whenever the softirq gets handled, at the end of
557  * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
558  *
559  * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
560  * The !softirq values are the minima across HRTIMER_ACTIVE_ALL, unless an actual
561  * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
562  *
563  * @active_mask must be one of:
564  *  - HRTIMER_ACTIVE_ALL,
565  *  - HRTIMER_ACTIVE_SOFT, or
566  *  - HRTIMER_ACTIVE_HARD.
567  */
568 static ktime_t
__hrtimer_get_next_event(struct hrtimer_cpu_base * cpu_base,unsigned int active_mask)569 __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
570 {
571 	unsigned int active;
572 	struct hrtimer *next_timer = NULL;
573 	ktime_t expires_next = KTIME_MAX;
574 
575 	if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
576 		active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
577 		cpu_base->softirq_next_timer = NULL;
578 		expires_next = __hrtimer_next_event_base(cpu_base, NULL,
579 							 active, KTIME_MAX);
580 
581 		next_timer = cpu_base->softirq_next_timer;
582 	}
583 
584 	if (active_mask & HRTIMER_ACTIVE_HARD) {
585 		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
586 		cpu_base->next_timer = next_timer;
587 		expires_next = __hrtimer_next_event_base(cpu_base, NULL, active,
588 							 expires_next);
589 	}
590 
591 	return expires_next;
592 }
593 
hrtimer_update_next_event(struct hrtimer_cpu_base * cpu_base)594 static ktime_t hrtimer_update_next_event(struct hrtimer_cpu_base *cpu_base)
595 {
596 	ktime_t expires_next, soft = KTIME_MAX;
597 
598 	/*
599 	 * If the soft interrupt has already been activated, ignore the
600 	 * soft bases. They will be handled in the already raised soft
601 	 * interrupt.
602 	 */
603 	if (!cpu_base->softirq_activated) {
604 		soft = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
605 		/*
606 		 * Update the soft expiry time. clock_settime() might have
607 		 * affected it.
608 		 */
609 		cpu_base->softirq_expires_next = soft;
610 	}
611 
612 	expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
613 	/*
614 	 * If a softirq timer is expiring first, update cpu_base->next_timer
615 	 * and program the hardware with the soft expiry time.
616 	 */
617 	if (expires_next > soft) {
618 		cpu_base->next_timer = cpu_base->softirq_next_timer;
619 		expires_next = soft;
620 	}
621 
622 	return expires_next;
623 }
624 
hrtimer_update_base(struct hrtimer_cpu_base * base)625 static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
626 {
627 	ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
628 	ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
629 	ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
630 
631 	ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
632 					    offs_real, offs_boot, offs_tai);
633 
634 	base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
635 	base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
636 	base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
637 
638 	return now;
639 }
640 
641 /*
642  * Is the high resolution mode active ?
643  */
__hrtimer_hres_active(struct hrtimer_cpu_base * cpu_base)644 static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
645 {
646 	return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
647 		cpu_base->hres_active : 0;
648 }
649 
hrtimer_hres_active(void)650 static inline int hrtimer_hres_active(void)
651 {
652 	return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
653 }
654 
__hrtimer_reprogram(struct hrtimer_cpu_base * cpu_base,struct hrtimer * next_timer,ktime_t expires_next)655 static void __hrtimer_reprogram(struct hrtimer_cpu_base *cpu_base,
656 				struct hrtimer *next_timer,
657 				ktime_t expires_next)
658 {
659 	cpu_base->expires_next = expires_next;
660 
661 	/*
662 	 * If hres is not active, hardware does not have to be
663 	 * reprogrammed yet.
664 	 *
665 	 * If a hang was detected in the last timer interrupt then we
666 	 * leave the hang delay active in the hardware. We want the
667 	 * system to make progress. That also prevents the following
668 	 * scenario:
669 	 * T1 expires 50ms from now
670 	 * T2 expires 5s from now
671 	 *
672 	 * T1 is removed, so this code is called and would reprogram
673 	 * the hardware to 5s from now. Any hrtimer_start after that
674 	 * will not reprogram the hardware due to hang_detected being
675 	 * set. So we'd effectively block all timers until the T2 event
676 	 * fires.
677 	 */
678 	if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
679 		return;
680 
681 	tick_program_event(expires_next, 1);
682 }
683 
684 /*
685  * Reprogram the event source with checking both queues for the
686  * next event
687  * Called with interrupts disabled and base->lock held
688  */
689 static void
hrtimer_force_reprogram(struct hrtimer_cpu_base * cpu_base,int skip_equal)690 hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
691 {
692 	ktime_t expires_next;
693 
694 	expires_next = hrtimer_update_next_event(cpu_base);
695 
696 	if (skip_equal && expires_next == cpu_base->expires_next)
697 		return;
698 
699 	__hrtimer_reprogram(cpu_base, cpu_base->next_timer, expires_next);
700 }
701 
702 /* High resolution timer related functions */
703 #ifdef CONFIG_HIGH_RES_TIMERS
704 
705 /*
706  * High resolution timer enabled ?
707  */
708 static bool hrtimer_hres_enabled __read_mostly  = true;
709 unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
710 EXPORT_SYMBOL_GPL(hrtimer_resolution);
711 
712 /*
713  * Enable / Disable high resolution mode
714  */
setup_hrtimer_hres(char * str)715 static int __init setup_hrtimer_hres(char *str)
716 {
717 	return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
718 }
719 
720 __setup("highres=", setup_hrtimer_hres);
721 
722 /*
723  * hrtimer_high_res_enabled - query, if the highres mode is enabled
724  */
hrtimer_is_hres_enabled(void)725 static inline int hrtimer_is_hres_enabled(void)
726 {
727 	return hrtimer_hres_enabled;
728 }
729 
730 static void retrigger_next_event(void *arg);
731 
732 /*
733  * Switch to high resolution mode
734  */
hrtimer_switch_to_hres(void)735 static void hrtimer_switch_to_hres(void)
736 {
737 	struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
738 
739 	if (tick_init_highres()) {
740 		pr_warn("Could not switch to high resolution mode on CPU %u\n",
741 			base->cpu);
742 		return;
743 	}
744 	base->hres_active = 1;
745 	hrtimer_resolution = HIGH_RES_NSEC;
746 
747 	tick_setup_sched_timer();
748 	/* "Retrigger" the interrupt to get things going */
749 	retrigger_next_event(NULL);
750 }
751 
752 #else
753 
hrtimer_is_hres_enabled(void)754 static inline int hrtimer_is_hres_enabled(void) { return 0; }
hrtimer_switch_to_hres(void)755 static inline void hrtimer_switch_to_hres(void) { }
756 
757 #endif /* CONFIG_HIGH_RES_TIMERS */
758 /*
759  * Retrigger next event is called after clock was set with interrupts
760  * disabled through an SMP function call or directly from low level
761  * resume code.
762  *
763  * This is only invoked when:
764  *	- CONFIG_HIGH_RES_TIMERS is enabled.
765  *	- CONFIG_NOHZ_COMMON is enabled
766  *
767  * For the other cases this function is empty and because the call sites
768  * are optimized out it vanishes as well, i.e. no need for lots of
769  * #ifdeffery.
770  */
retrigger_next_event(void * arg)771 static void retrigger_next_event(void *arg)
772 {
773 	struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
774 
775 	/*
776 	 * When high resolution mode or nohz is active, then the offsets of
777 	 * CLOCK_REALTIME/TAI/BOOTTIME have to be updated. Otherwise the
778 	 * next tick will take care of that.
779 	 *
780 	 * If high resolution mode is active then the next expiring timer
781 	 * must be reevaluated and the clock event device reprogrammed if
782 	 * necessary.
783 	 *
784 	 * In the NOHZ case the update of the offset and the reevaluation
785 	 * of the next expiring timer is enough. The return from the SMP
786 	 * function call will take care of the reprogramming in case the
787 	 * CPU was in a NOHZ idle sleep.
788 	 */
789 	if (!__hrtimer_hres_active(base) && !tick_nohz_active)
790 		return;
791 
792 	raw_spin_lock(&base->lock);
793 	hrtimer_update_base(base);
794 	if (__hrtimer_hres_active(base))
795 		hrtimer_force_reprogram(base, 0);
796 	else
797 		hrtimer_update_next_event(base);
798 	raw_spin_unlock(&base->lock);
799 }
800 
801 /*
802  * When a timer is enqueued and expires earlier than the already enqueued
803  * timers, we have to check, whether it expires earlier than the timer for
804  * which the clock event device was armed.
805  *
806  * Called with interrupts disabled and base->cpu_base.lock held
807  */
hrtimer_reprogram(struct hrtimer * timer,bool reprogram)808 static void hrtimer_reprogram(struct hrtimer *timer, bool reprogram)
809 {
810 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
811 	struct hrtimer_clock_base *base = timer->base;
812 	ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
813 
814 	WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
815 
816 	/*
817 	 * CLOCK_REALTIME timer might be requested with an absolute
818 	 * expiry time which is less than base->offset. Set it to 0.
819 	 */
820 	if (expires < 0)
821 		expires = 0;
822 
823 	if (timer->is_soft) {
824 		/*
825 		 * soft hrtimer could be started on a remote CPU. In this
826 		 * case softirq_expires_next needs to be updated on the
827 		 * remote CPU. The soft hrtimer will not expire before the
828 		 * first hard hrtimer on the remote CPU -
829 		 * hrtimer_check_target() prevents this case.
830 		 */
831 		struct hrtimer_cpu_base *timer_cpu_base = base->cpu_base;
832 
833 		if (timer_cpu_base->softirq_activated)
834 			return;
835 
836 		if (!ktime_before(expires, timer_cpu_base->softirq_expires_next))
837 			return;
838 
839 		timer_cpu_base->softirq_next_timer = timer;
840 		timer_cpu_base->softirq_expires_next = expires;
841 
842 		if (!ktime_before(expires, timer_cpu_base->expires_next) ||
843 		    !reprogram)
844 			return;
845 	}
846 
847 	/*
848 	 * If the timer is not on the current cpu, we cannot reprogram
849 	 * the other cpus clock event device.
850 	 */
851 	if (base->cpu_base != cpu_base)
852 		return;
853 
854 	if (expires >= cpu_base->expires_next)
855 		return;
856 
857 	/*
858 	 * If the hrtimer interrupt is running, then it will reevaluate the
859 	 * clock bases and reprogram the clock event device.
860 	 */
861 	if (cpu_base->in_hrtirq)
862 		return;
863 
864 	cpu_base->next_timer = timer;
865 
866 	__hrtimer_reprogram(cpu_base, timer, expires);
867 }
868 
update_needs_ipi(struct hrtimer_cpu_base * cpu_base,unsigned int active)869 static bool update_needs_ipi(struct hrtimer_cpu_base *cpu_base,
870 			     unsigned int active)
871 {
872 	struct hrtimer_clock_base *base;
873 	unsigned int seq;
874 	ktime_t expires;
875 
876 	/*
877 	 * Update the base offsets unconditionally so the following
878 	 * checks whether the SMP function call is required works.
879 	 *
880 	 * The update is safe even when the remote CPU is in the hrtimer
881 	 * interrupt or the hrtimer soft interrupt and expiring affected
882 	 * bases. Either it will see the update before handling a base or
883 	 * it will see it when it finishes the processing and reevaluates
884 	 * the next expiring timer.
885 	 */
886 	seq = cpu_base->clock_was_set_seq;
887 	hrtimer_update_base(cpu_base);
888 
889 	/*
890 	 * If the sequence did not change over the update then the
891 	 * remote CPU already handled it.
892 	 */
893 	if (seq == cpu_base->clock_was_set_seq)
894 		return false;
895 
896 	/*
897 	 * If the remote CPU is currently handling an hrtimer interrupt, it
898 	 * will reevaluate the first expiring timer of all clock bases
899 	 * before reprogramming. Nothing to do here.
900 	 */
901 	if (cpu_base->in_hrtirq)
902 		return false;
903 
904 	/*
905 	 * Walk the affected clock bases and check whether the first expiring
906 	 * timer in a clock base is moving ahead of the first expiring timer of
907 	 * @cpu_base. If so, the IPI must be invoked because per CPU clock
908 	 * event devices cannot be remotely reprogrammed.
909 	 */
910 	active &= cpu_base->active_bases;
911 
912 	for_each_active_base(base, cpu_base, active) {
913 		struct timerqueue_node *next;
914 
915 		next = timerqueue_getnext(&base->active);
916 		expires = ktime_sub(next->expires, base->offset);
917 		if (expires < cpu_base->expires_next)
918 			return true;
919 
920 		/* Extra check for softirq clock bases */
921 		if (base->clockid < HRTIMER_BASE_MONOTONIC_SOFT)
922 			continue;
923 		if (cpu_base->softirq_activated)
924 			continue;
925 		if (expires < cpu_base->softirq_expires_next)
926 			return true;
927 	}
928 	return false;
929 }
930 
931 /*
932  * Clock was set. This might affect CLOCK_REALTIME, CLOCK_TAI and
933  * CLOCK_BOOTTIME (for late sleep time injection).
934  *
935  * This requires to update the offsets for these clocks
936  * vs. CLOCK_MONOTONIC. When high resolution timers are enabled, then this
937  * also requires to eventually reprogram the per CPU clock event devices
938  * when the change moves an affected timer ahead of the first expiring
939  * timer on that CPU. Obviously remote per CPU clock event devices cannot
940  * be reprogrammed. The other reason why an IPI has to be sent is when the
941  * system is in !HIGH_RES and NOHZ mode. The NOHZ mode updates the offsets
942  * in the tick, which obviously might be stopped, so this has to bring out
943  * the remote CPU which might sleep in idle to get this sorted.
944  */
clock_was_set(unsigned int bases)945 void clock_was_set(unsigned int bases)
946 {
947 	struct hrtimer_cpu_base *cpu_base = raw_cpu_ptr(&hrtimer_bases);
948 	cpumask_var_t mask;
949 	int cpu;
950 
951 	if (!__hrtimer_hres_active(cpu_base) && !tick_nohz_active)
952 		goto out_timerfd;
953 
954 	if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
955 		on_each_cpu(retrigger_next_event, NULL, 1);
956 		goto out_timerfd;
957 	}
958 
959 	/* Avoid interrupting CPUs if possible */
960 	cpus_read_lock();
961 	for_each_online_cpu(cpu) {
962 		unsigned long flags;
963 
964 		cpu_base = &per_cpu(hrtimer_bases, cpu);
965 		raw_spin_lock_irqsave(&cpu_base->lock, flags);
966 
967 		if (update_needs_ipi(cpu_base, bases))
968 			cpumask_set_cpu(cpu, mask);
969 
970 		raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
971 	}
972 
973 	preempt_disable();
974 	smp_call_function_many(mask, retrigger_next_event, NULL, 1);
975 	preempt_enable();
976 	cpus_read_unlock();
977 	free_cpumask_var(mask);
978 
979 out_timerfd:
980 	timerfd_clock_was_set();
981 }
982 
clock_was_set_work(struct work_struct * work)983 static void clock_was_set_work(struct work_struct *work)
984 {
985 	clock_was_set(CLOCK_SET_WALL);
986 }
987 
988 static DECLARE_WORK(hrtimer_work, clock_was_set_work);
989 
990 /*
991  * Called from timekeeping code to reprogram the hrtimer interrupt device
992  * on all cpus and to notify timerfd.
993  */
clock_was_set_delayed(void)994 void clock_was_set_delayed(void)
995 {
996 	schedule_work(&hrtimer_work);
997 }
998 
999 /*
1000  * Called during resume either directly from via timekeeping_resume()
1001  * or in the case of s2idle from tick_unfreeze() to ensure that the
1002  * hrtimers are up to date.
1003  */
hrtimers_resume_local(void)1004 void hrtimers_resume_local(void)
1005 {
1006 	lockdep_assert_irqs_disabled();
1007 	/* Retrigger on the local CPU */
1008 	retrigger_next_event(NULL);
1009 }
1010 
1011 /*
1012  * Counterpart to lock_hrtimer_base above:
1013  */
1014 static inline
unlock_hrtimer_base(const struct hrtimer * timer,unsigned long * flags)1015 void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
1016 {
1017 	raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
1018 }
1019 
1020 /**
1021  * hrtimer_forward - forward the timer expiry
1022  * @timer:	hrtimer to forward
1023  * @now:	forward past this time
1024  * @interval:	the interval to forward
1025  *
1026  * Forward the timer expiry so it will expire in the future.
1027  * Returns the number of overruns.
1028  *
1029  * Can be safely called from the callback function of @timer. If
1030  * called from other contexts @timer must neither be enqueued nor
1031  * running the callback and the caller needs to take care of
1032  * serialization.
1033  *
1034  * Note: This only updates the timer expiry value and does not requeue
1035  * the timer.
1036  */
hrtimer_forward(struct hrtimer * timer,ktime_t now,ktime_t interval)1037 u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
1038 {
1039 	u64 orun = 1;
1040 	ktime_t delta;
1041 
1042 	delta = ktime_sub(now, hrtimer_get_expires(timer));
1043 
1044 	if (delta < 0)
1045 		return 0;
1046 
1047 	if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
1048 		return 0;
1049 
1050 	if (interval < hrtimer_resolution)
1051 		interval = hrtimer_resolution;
1052 
1053 	if (unlikely(delta >= interval)) {
1054 		s64 incr = ktime_to_ns(interval);
1055 
1056 		orun = ktime_divns(delta, incr);
1057 		hrtimer_add_expires_ns(timer, incr * orun);
1058 		if (hrtimer_get_expires_tv64(timer) > now)
1059 			return orun;
1060 		/*
1061 		 * This (and the ktime_add() below) is the
1062 		 * correction for exact:
1063 		 */
1064 		orun++;
1065 	}
1066 	hrtimer_add_expires(timer, interval);
1067 
1068 	return orun;
1069 }
1070 EXPORT_SYMBOL_GPL(hrtimer_forward);
1071 
1072 /*
1073  * enqueue_hrtimer - internal function to (re)start a timer
1074  *
1075  * The timer is inserted in expiry order. Insertion into the
1076  * red black tree is O(log(n)). Must hold the base lock.
1077  *
1078  * Returns 1 when the new timer is the leftmost timer in the tree.
1079  */
enqueue_hrtimer(struct hrtimer * timer,struct hrtimer_clock_base * base,enum hrtimer_mode mode)1080 static int enqueue_hrtimer(struct hrtimer *timer,
1081 			   struct hrtimer_clock_base *base,
1082 			   enum hrtimer_mode mode)
1083 {
1084 	debug_activate(timer, mode);
1085 
1086 	base->cpu_base->active_bases |= 1 << base->index;
1087 
1088 	/* Pairs with the lockless read in hrtimer_is_queued() */
1089 	WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
1090 
1091 	return timerqueue_add(&base->active, &timer->node);
1092 }
1093 
1094 /*
1095  * __remove_hrtimer - internal function to remove a timer
1096  *
1097  * Caller must hold the base lock.
1098  *
1099  * High resolution timer mode reprograms the clock event device when the
1100  * timer is the one which expires next. The caller can disable this by setting
1101  * reprogram to zero. This is useful, when the context does a reprogramming
1102  * anyway (e.g. timer interrupt)
1103  */
__remove_hrtimer(struct hrtimer * timer,struct hrtimer_clock_base * base,u8 newstate,int reprogram)1104 static void __remove_hrtimer(struct hrtimer *timer,
1105 			     struct hrtimer_clock_base *base,
1106 			     u8 newstate, int reprogram)
1107 {
1108 	struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1109 	u8 state = timer->state;
1110 
1111 	/* Pairs with the lockless read in hrtimer_is_queued() */
1112 	WRITE_ONCE(timer->state, newstate);
1113 	if (!(state & HRTIMER_STATE_ENQUEUED))
1114 		return;
1115 
1116 	if (!timerqueue_del(&base->active, &timer->node))
1117 		cpu_base->active_bases &= ~(1 << base->index);
1118 
1119 	/*
1120 	 * Note: If reprogram is false we do not update
1121 	 * cpu_base->next_timer. This happens when we remove the first
1122 	 * timer on a remote cpu. No harm as we never dereference
1123 	 * cpu_base->next_timer. So the worst thing what can happen is
1124 	 * an superfluous call to hrtimer_force_reprogram() on the
1125 	 * remote cpu later on if the same timer gets enqueued again.
1126 	 */
1127 	if (reprogram && timer == cpu_base->next_timer)
1128 		hrtimer_force_reprogram(cpu_base, 1);
1129 }
1130 
1131 /*
1132  * remove hrtimer, called with base lock held
1133  */
1134 static inline int
remove_hrtimer(struct hrtimer * timer,struct hrtimer_clock_base * base,bool restart,bool keep_local)1135 remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base,
1136 	       bool restart, bool keep_local)
1137 {
1138 	u8 state = timer->state;
1139 
1140 	if (state & HRTIMER_STATE_ENQUEUED) {
1141 		bool reprogram;
1142 
1143 		/*
1144 		 * Remove the timer and force reprogramming when high
1145 		 * resolution mode is active and the timer is on the current
1146 		 * CPU. If we remove a timer on another CPU, reprogramming is
1147 		 * skipped. The interrupt event on this CPU is fired and
1148 		 * reprogramming happens in the interrupt handler. This is a
1149 		 * rare case and less expensive than a smp call.
1150 		 */
1151 		debug_deactivate(timer);
1152 		reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1153 
1154 		/*
1155 		 * If the timer is not restarted then reprogramming is
1156 		 * required if the timer is local. If it is local and about
1157 		 * to be restarted, avoid programming it twice (on removal
1158 		 * and a moment later when it's requeued).
1159 		 */
1160 		if (!restart)
1161 			state = HRTIMER_STATE_INACTIVE;
1162 		else
1163 			reprogram &= !keep_local;
1164 
1165 		__remove_hrtimer(timer, base, state, reprogram);
1166 		return 1;
1167 	}
1168 	return 0;
1169 }
1170 
hrtimer_update_lowres(struct hrtimer * timer,ktime_t tim,const enum hrtimer_mode mode)1171 static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
1172 					    const enum hrtimer_mode mode)
1173 {
1174 #ifdef CONFIG_TIME_LOW_RES
1175 	/*
1176 	 * CONFIG_TIME_LOW_RES indicates that the system has no way to return
1177 	 * granular time values. For relative timers we add hrtimer_resolution
1178 	 * (i.e. one jiffie) to prevent short timeouts.
1179 	 */
1180 	timer->is_rel = mode & HRTIMER_MODE_REL;
1181 	if (timer->is_rel)
1182 		tim = ktime_add_safe(tim, hrtimer_resolution);
1183 #endif
1184 	return tim;
1185 }
1186 
1187 static void
hrtimer_update_softirq_timer(struct hrtimer_cpu_base * cpu_base,bool reprogram)1188 hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
1189 {
1190 	ktime_t expires;
1191 
1192 	/*
1193 	 * Find the next SOFT expiration.
1194 	 */
1195 	expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
1196 
1197 	/*
1198 	 * reprogramming needs to be triggered, even if the next soft
1199 	 * hrtimer expires at the same time than the next hard
1200 	 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
1201 	 */
1202 	if (expires == KTIME_MAX)
1203 		return;
1204 
1205 	/*
1206 	 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
1207 	 * cpu_base->*expires_next is only set by hrtimer_reprogram()
1208 	 */
1209 	hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
1210 }
1211 
__hrtimer_start_range_ns(struct hrtimer * timer,ktime_t tim,u64 delta_ns,const enum hrtimer_mode mode,struct hrtimer_clock_base * base)1212 static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1213 				    u64 delta_ns, const enum hrtimer_mode mode,
1214 				    struct hrtimer_clock_base *base)
1215 {
1216 	struct hrtimer_clock_base *new_base;
1217 	bool force_local, first;
1218 
1219 	/*
1220 	 * If the timer is on the local cpu base and is the first expiring
1221 	 * timer then this might end up reprogramming the hardware twice
1222 	 * (on removal and on enqueue). To avoid that by prevent the
1223 	 * reprogram on removal, keep the timer local to the current CPU
1224 	 * and enforce reprogramming after it is queued no matter whether
1225 	 * it is the new first expiring timer again or not.
1226 	 */
1227 	force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1228 	force_local &= base->cpu_base->next_timer == timer;
1229 
1230 	/*
1231 	 * Remove an active timer from the queue. In case it is not queued
1232 	 * on the current CPU, make sure that remove_hrtimer() updates the
1233 	 * remote data correctly.
1234 	 *
1235 	 * If it's on the current CPU and the first expiring timer, then
1236 	 * skip reprogramming, keep the timer local and enforce
1237 	 * reprogramming later if it was the first expiring timer.  This
1238 	 * avoids programming the underlying clock event twice (once at
1239 	 * removal and once after enqueue).
1240 	 */
1241 	remove_hrtimer(timer, base, true, force_local);
1242 
1243 	if (mode & HRTIMER_MODE_REL)
1244 		tim = ktime_add_safe(tim, base->get_time());
1245 
1246 	tim = hrtimer_update_lowres(timer, tim, mode);
1247 
1248 	hrtimer_set_expires_range_ns(timer, tim, delta_ns);
1249 
1250 	/* Switch the timer base, if necessary: */
1251 	if (!force_local) {
1252 		new_base = switch_hrtimer_base(timer, base,
1253 					       mode & HRTIMER_MODE_PINNED);
1254 	} else {
1255 		new_base = base;
1256 	}
1257 
1258 	first = enqueue_hrtimer(timer, new_base, mode);
1259 	if (!force_local)
1260 		return first;
1261 
1262 	/*
1263 	 * Timer was forced to stay on the current CPU to avoid
1264 	 * reprogramming on removal and enqueue. Force reprogram the
1265 	 * hardware by evaluating the new first expiring timer.
1266 	 */
1267 	hrtimer_force_reprogram(new_base->cpu_base, 1);
1268 	return 0;
1269 }
1270 
1271 /**
1272  * hrtimer_start_range_ns - (re)start an hrtimer
1273  * @timer:	the timer to be added
1274  * @tim:	expiry time
1275  * @delta_ns:	"slack" range for the timer
1276  * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
1277  *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
1278  *		softirq based mode is considered for debug purpose only!
1279  */
hrtimer_start_range_ns(struct hrtimer * timer,ktime_t tim,u64 delta_ns,const enum hrtimer_mode mode)1280 void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1281 			    u64 delta_ns, const enum hrtimer_mode mode)
1282 {
1283 	struct hrtimer_clock_base *base;
1284 	unsigned long flags;
1285 
1286 	/*
1287 	 * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
1288 	 * match on CONFIG_PREEMPT_RT = n. With PREEMPT_RT check the hard
1289 	 * expiry mode because unmarked timers are moved to softirq expiry.
1290 	 */
1291 	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
1292 		WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
1293 	else
1294 		WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard);
1295 
1296 	base = lock_hrtimer_base(timer, &flags);
1297 
1298 	if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
1299 		hrtimer_reprogram(timer, true);
1300 
1301 	unlock_hrtimer_base(timer, &flags);
1302 }
1303 EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1304 
1305 /**
1306  * hrtimer_try_to_cancel - try to deactivate a timer
1307  * @timer:	hrtimer to stop
1308  *
1309  * Returns:
1310  *
1311  *  *  0 when the timer was not active
1312  *  *  1 when the timer was active
1313  *  * -1 when the timer is currently executing the callback function and
1314  *    cannot be stopped
1315  */
hrtimer_try_to_cancel(struct hrtimer * timer)1316 int hrtimer_try_to_cancel(struct hrtimer *timer)
1317 {
1318 	struct hrtimer_clock_base *base;
1319 	unsigned long flags;
1320 	int ret = -1;
1321 
1322 	/*
1323 	 * Check lockless first. If the timer is not active (neither
1324 	 * enqueued nor running the callback, nothing to do here.  The
1325 	 * base lock does not serialize against a concurrent enqueue,
1326 	 * so we can avoid taking it.
1327 	 */
1328 	if (!hrtimer_active(timer))
1329 		return 0;
1330 
1331 	base = lock_hrtimer_base(timer, &flags);
1332 
1333 	if (!hrtimer_callback_running(timer))
1334 		ret = remove_hrtimer(timer, base, false, false);
1335 
1336 	unlock_hrtimer_base(timer, &flags);
1337 
1338 	return ret;
1339 
1340 }
1341 EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1342 
1343 #ifdef CONFIG_PREEMPT_RT
hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base * base)1344 static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
1345 {
1346 	spin_lock_init(&base->softirq_expiry_lock);
1347 }
1348 
hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base * base)1349 static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
1350 {
1351 	spin_lock(&base->softirq_expiry_lock);
1352 }
1353 
hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base * base)1354 static void hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base)
1355 {
1356 	spin_unlock(&base->softirq_expiry_lock);
1357 }
1358 
1359 /*
1360  * The counterpart to hrtimer_cancel_wait_running().
1361  *
1362  * If there is a waiter for cpu_base->expiry_lock, then it was waiting for
1363  * the timer callback to finish. Drop expiry_lock and reacquire it. That
1364  * allows the waiter to acquire the lock and make progress.
1365  */
hrtimer_sync_wait_running(struct hrtimer_cpu_base * cpu_base,unsigned long flags)1366 static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base,
1367 				      unsigned long flags)
1368 {
1369 	if (atomic_read(&cpu_base->timer_waiters)) {
1370 		raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1371 		spin_unlock(&cpu_base->softirq_expiry_lock);
1372 		spin_lock(&cpu_base->softirq_expiry_lock);
1373 		raw_spin_lock_irq(&cpu_base->lock);
1374 	}
1375 }
1376 
1377 /*
1378  * This function is called on PREEMPT_RT kernels when the fast path
1379  * deletion of a timer failed because the timer callback function was
1380  * running.
1381  *
1382  * This prevents priority inversion: if the soft irq thread is preempted
1383  * in the middle of a timer callback, then calling del_timer_sync() can
1384  * lead to two issues:
1385  *
1386  *  - If the caller is on a remote CPU then it has to spin wait for the timer
1387  *    handler to complete. This can result in unbound priority inversion.
1388  *
1389  *  - If the caller originates from the task which preempted the timer
1390  *    handler on the same CPU, then spin waiting for the timer handler to
1391  *    complete is never going to end.
1392  */
hrtimer_cancel_wait_running(const struct hrtimer * timer)1393 void hrtimer_cancel_wait_running(const struct hrtimer *timer)
1394 {
1395 	/* Lockless read. Prevent the compiler from reloading it below */
1396 	struct hrtimer_clock_base *base = READ_ONCE(timer->base);
1397 
1398 	/*
1399 	 * Just relax if the timer expires in hard interrupt context or if
1400 	 * it is currently on the migration base.
1401 	 */
1402 	if (!timer->is_soft || is_migration_base(base)) {
1403 		cpu_relax();
1404 		return;
1405 	}
1406 
1407 	/*
1408 	 * Mark the base as contended and grab the expiry lock, which is
1409 	 * held by the softirq across the timer callback. Drop the lock
1410 	 * immediately so the softirq can expire the next timer. In theory
1411 	 * the timer could already be running again, but that's more than
1412 	 * unlikely and just causes another wait loop.
1413 	 */
1414 	atomic_inc(&base->cpu_base->timer_waiters);
1415 	spin_lock_bh(&base->cpu_base->softirq_expiry_lock);
1416 	atomic_dec(&base->cpu_base->timer_waiters);
1417 	spin_unlock_bh(&base->cpu_base->softirq_expiry_lock);
1418 }
1419 #else
1420 static inline void
hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base * base)1421 hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
1422 static inline void
hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base * base)1423 hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
1424 static inline void
hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base * base)1425 hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
hrtimer_sync_wait_running(struct hrtimer_cpu_base * base,unsigned long flags)1426 static inline void hrtimer_sync_wait_running(struct hrtimer_cpu_base *base,
1427 					     unsigned long flags) { }
1428 #endif
1429 
1430 /**
1431  * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1432  * @timer:	the timer to be cancelled
1433  *
1434  * Returns:
1435  *  0 when the timer was not active
1436  *  1 when the timer was active
1437  */
hrtimer_cancel(struct hrtimer * timer)1438 int hrtimer_cancel(struct hrtimer *timer)
1439 {
1440 	int ret;
1441 
1442 	do {
1443 		ret = hrtimer_try_to_cancel(timer);
1444 
1445 		if (ret < 0)
1446 			hrtimer_cancel_wait_running(timer);
1447 	} while (ret < 0);
1448 	return ret;
1449 }
1450 EXPORT_SYMBOL_GPL(hrtimer_cancel);
1451 
1452 /**
1453  * __hrtimer_get_remaining - get remaining time for the timer
1454  * @timer:	the timer to read
1455  * @adjust:	adjust relative timers when CONFIG_TIME_LOW_RES=y
1456  */
__hrtimer_get_remaining(const struct hrtimer * timer,bool adjust)1457 ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
1458 {
1459 	unsigned long flags;
1460 	ktime_t rem;
1461 
1462 	lock_hrtimer_base(timer, &flags);
1463 	if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
1464 		rem = hrtimer_expires_remaining_adjusted(timer);
1465 	else
1466 		rem = hrtimer_expires_remaining(timer);
1467 	unlock_hrtimer_base(timer, &flags);
1468 
1469 	return rem;
1470 }
1471 EXPORT_SYMBOL_GPL(__hrtimer_get_remaining);
1472 
1473 #ifdef CONFIG_NO_HZ_COMMON
1474 /**
1475  * hrtimer_get_next_event - get the time until next expiry event
1476  *
1477  * Returns the next expiry time or KTIME_MAX if no timer is pending.
1478  */
hrtimer_get_next_event(void)1479 u64 hrtimer_get_next_event(void)
1480 {
1481 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1482 	u64 expires = KTIME_MAX;
1483 	unsigned long flags;
1484 
1485 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1486 
1487 	if (!__hrtimer_hres_active(cpu_base))
1488 		expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
1489 
1490 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1491 
1492 	return expires;
1493 }
1494 
1495 /**
1496  * hrtimer_next_event_without - time until next expiry event w/o one timer
1497  * @exclude:	timer to exclude
1498  *
1499  * Returns the next expiry time over all timers except for the @exclude one or
1500  * KTIME_MAX if none of them is pending.
1501  */
hrtimer_next_event_without(const struct hrtimer * exclude)1502 u64 hrtimer_next_event_without(const struct hrtimer *exclude)
1503 {
1504 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1505 	u64 expires = KTIME_MAX;
1506 	unsigned long flags;
1507 
1508 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1509 
1510 	if (__hrtimer_hres_active(cpu_base)) {
1511 		unsigned int active;
1512 
1513 		if (!cpu_base->softirq_activated) {
1514 			active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
1515 			expires = __hrtimer_next_event_base(cpu_base, exclude,
1516 							    active, KTIME_MAX);
1517 		}
1518 		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
1519 		expires = __hrtimer_next_event_base(cpu_base, exclude, active,
1520 						    expires);
1521 	}
1522 
1523 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1524 
1525 	return expires;
1526 }
1527 #endif
1528 
hrtimer_clockid_to_base(clockid_t clock_id)1529 static inline int hrtimer_clockid_to_base(clockid_t clock_id)
1530 {
1531 	if (likely(clock_id < MAX_CLOCKS)) {
1532 		int base = hrtimer_clock_to_base_table[clock_id];
1533 
1534 		if (likely(base != HRTIMER_MAX_CLOCK_BASES))
1535 			return base;
1536 	}
1537 	WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
1538 	return HRTIMER_BASE_MONOTONIC;
1539 }
1540 
__hrtimer_init(struct hrtimer * timer,clockid_t clock_id,enum hrtimer_mode mode)1541 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1542 			   enum hrtimer_mode mode)
1543 {
1544 	bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
1545 	struct hrtimer_cpu_base *cpu_base;
1546 	int base;
1547 
1548 	/*
1549 	 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1550 	 * marked for hard interrupt expiry mode are moved into soft
1551 	 * interrupt context for latency reasons and because the callbacks
1552 	 * can invoke functions which might sleep on RT, e.g. spin_lock().
1553 	 */
1554 	if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD))
1555 		softtimer = true;
1556 
1557 	memset(timer, 0, sizeof(struct hrtimer));
1558 
1559 	cpu_base = raw_cpu_ptr(&hrtimer_bases);
1560 
1561 	/*
1562 	 * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
1563 	 * clock modifications, so they needs to become CLOCK_MONOTONIC to
1564 	 * ensure POSIX compliance.
1565 	 */
1566 	if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
1567 		clock_id = CLOCK_MONOTONIC;
1568 
1569 	base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
1570 	base += hrtimer_clockid_to_base(clock_id);
1571 	timer->is_soft = softtimer;
1572 	timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
1573 	timer->base = &cpu_base->clock_base[base];
1574 	timerqueue_init(&timer->node);
1575 }
1576 
1577 /**
1578  * hrtimer_init - initialize a timer to the given clock
1579  * @timer:	the timer to be initialized
1580  * @clock_id:	the clock to be used
1581  * @mode:       The modes which are relevant for initialization:
1582  *              HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
1583  *              HRTIMER_MODE_REL_SOFT
1584  *
1585  *              The PINNED variants of the above can be handed in,
1586  *              but the PINNED bit is ignored as pinning happens
1587  *              when the hrtimer is started
1588  */
hrtimer_init(struct hrtimer * timer,clockid_t clock_id,enum hrtimer_mode mode)1589 void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1590 		  enum hrtimer_mode mode)
1591 {
1592 	debug_init(timer, clock_id, mode);
1593 	__hrtimer_init(timer, clock_id, mode);
1594 }
1595 EXPORT_SYMBOL_GPL(hrtimer_init);
1596 
1597 /*
1598  * A timer is active, when it is enqueued into the rbtree or the
1599  * callback function is running or it's in the state of being migrated
1600  * to another cpu.
1601  *
1602  * It is important for this function to not return a false negative.
1603  */
hrtimer_active(const struct hrtimer * timer)1604 bool hrtimer_active(const struct hrtimer *timer)
1605 {
1606 	struct hrtimer_clock_base *base;
1607 	unsigned int seq;
1608 
1609 	do {
1610 		base = READ_ONCE(timer->base);
1611 		seq = raw_read_seqcount_begin(&base->seq);
1612 
1613 		if (timer->state != HRTIMER_STATE_INACTIVE ||
1614 		    base->running == timer)
1615 			return true;
1616 
1617 	} while (read_seqcount_retry(&base->seq, seq) ||
1618 		 base != READ_ONCE(timer->base));
1619 
1620 	return false;
1621 }
1622 EXPORT_SYMBOL_GPL(hrtimer_active);
1623 
1624 /*
1625  * The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
1626  * distinct sections:
1627  *
1628  *  - queued:	the timer is queued
1629  *  - callback:	the timer is being ran
1630  *  - post:	the timer is inactive or (re)queued
1631  *
1632  * On the read side we ensure we observe timer->state and cpu_base->running
1633  * from the same section, if anything changed while we looked at it, we retry.
1634  * This includes timer->base changing because sequence numbers alone are
1635  * insufficient for that.
1636  *
1637  * The sequence numbers are required because otherwise we could still observe
1638  * a false negative if the read side got smeared over multiple consecutive
1639  * __run_hrtimer() invocations.
1640  */
1641 
__run_hrtimer(struct hrtimer_cpu_base * cpu_base,struct hrtimer_clock_base * base,struct hrtimer * timer,ktime_t * now,unsigned long flags)1642 static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
1643 			  struct hrtimer_clock_base *base,
1644 			  struct hrtimer *timer, ktime_t *now,
1645 			  unsigned long flags) __must_hold(&cpu_base->lock)
1646 {
1647 	enum hrtimer_restart (*fn)(struct hrtimer *);
1648 	bool expires_in_hardirq;
1649 	int restart;
1650 
1651 	lockdep_assert_held(&cpu_base->lock);
1652 
1653 	debug_deactivate(timer);
1654 	base->running = timer;
1655 
1656 	/*
1657 	 * Separate the ->running assignment from the ->state assignment.
1658 	 *
1659 	 * As with a regular write barrier, this ensures the read side in
1660 	 * hrtimer_active() cannot observe base->running == NULL &&
1661 	 * timer->state == INACTIVE.
1662 	 */
1663 	raw_write_seqcount_barrier(&base->seq);
1664 
1665 	__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
1666 	fn = timer->function;
1667 
1668 	/*
1669 	 * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
1670 	 * timer is restarted with a period then it becomes an absolute
1671 	 * timer. If its not restarted it does not matter.
1672 	 */
1673 	if (IS_ENABLED(CONFIG_TIME_LOW_RES))
1674 		timer->is_rel = false;
1675 
1676 	/*
1677 	 * The timer is marked as running in the CPU base, so it is
1678 	 * protected against migration to a different CPU even if the lock
1679 	 * is dropped.
1680 	 */
1681 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1682 	trace_hrtimer_expire_entry(timer, now);
1683 	expires_in_hardirq = lockdep_hrtimer_enter(timer);
1684 
1685 	restart = fn(timer);
1686 
1687 	lockdep_hrtimer_exit(expires_in_hardirq);
1688 	trace_hrtimer_expire_exit(timer);
1689 	raw_spin_lock_irq(&cpu_base->lock);
1690 
1691 	/*
1692 	 * Note: We clear the running state after enqueue_hrtimer and
1693 	 * we do not reprogram the event hardware. Happens either in
1694 	 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1695 	 *
1696 	 * Note: Because we dropped the cpu_base->lock above,
1697 	 * hrtimer_start_range_ns() can have popped in and enqueued the timer
1698 	 * for us already.
1699 	 */
1700 	if (restart != HRTIMER_NORESTART &&
1701 	    !(timer->state & HRTIMER_STATE_ENQUEUED))
1702 		enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
1703 
1704 	/*
1705 	 * Separate the ->running assignment from the ->state assignment.
1706 	 *
1707 	 * As with a regular write barrier, this ensures the read side in
1708 	 * hrtimer_active() cannot observe base->running.timer == NULL &&
1709 	 * timer->state == INACTIVE.
1710 	 */
1711 	raw_write_seqcount_barrier(&base->seq);
1712 
1713 	WARN_ON_ONCE(base->running != timer);
1714 	base->running = NULL;
1715 }
1716 
__hrtimer_run_queues(struct hrtimer_cpu_base * cpu_base,ktime_t now,unsigned long flags,unsigned int active_mask)1717 static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
1718 				 unsigned long flags, unsigned int active_mask)
1719 {
1720 	struct hrtimer_clock_base *base;
1721 	unsigned int active = cpu_base->active_bases & active_mask;
1722 
1723 	for_each_active_base(base, cpu_base, active) {
1724 		struct timerqueue_node *node;
1725 		ktime_t basenow;
1726 
1727 		basenow = ktime_add(now, base->offset);
1728 
1729 		while ((node = timerqueue_getnext(&base->active))) {
1730 			struct hrtimer *timer;
1731 
1732 			timer = container_of(node, struct hrtimer, node);
1733 
1734 			/*
1735 			 * The immediate goal for using the softexpires is
1736 			 * minimizing wakeups, not running timers at the
1737 			 * earliest interrupt after their soft expiration.
1738 			 * This allows us to avoid using a Priority Search
1739 			 * Tree, which can answer a stabbing query for
1740 			 * overlapping intervals and instead use the simple
1741 			 * BST we already have.
1742 			 * We don't add extra wakeups by delaying timers that
1743 			 * are right-of a not yet expired timer, because that
1744 			 * timer will have to trigger a wakeup anyway.
1745 			 */
1746 			if (basenow < hrtimer_get_softexpires_tv64(timer))
1747 				break;
1748 
1749 			__run_hrtimer(cpu_base, base, timer, &basenow, flags);
1750 			if (active_mask == HRTIMER_ACTIVE_SOFT)
1751 				hrtimer_sync_wait_running(cpu_base, flags);
1752 		}
1753 	}
1754 }
1755 
hrtimer_run_softirq(struct softirq_action * h)1756 static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
1757 {
1758 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1759 	unsigned long flags;
1760 	ktime_t now;
1761 
1762 	hrtimer_cpu_base_lock_expiry(cpu_base);
1763 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1764 
1765 	now = hrtimer_update_base(cpu_base);
1766 	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
1767 
1768 	cpu_base->softirq_activated = 0;
1769 	hrtimer_update_softirq_timer(cpu_base, true);
1770 
1771 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1772 	hrtimer_cpu_base_unlock_expiry(cpu_base);
1773 }
1774 
1775 #ifdef CONFIG_HIGH_RES_TIMERS
1776 
1777 /*
1778  * High resolution timer interrupt
1779  * Called with interrupts disabled
1780  */
hrtimer_interrupt(struct clock_event_device * dev)1781 void hrtimer_interrupt(struct clock_event_device *dev)
1782 {
1783 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1784 	ktime_t expires_next, now, entry_time, delta;
1785 	unsigned long flags;
1786 	int retries = 0;
1787 
1788 	BUG_ON(!cpu_base->hres_active);
1789 	cpu_base->nr_events++;
1790 	dev->next_event = KTIME_MAX;
1791 
1792 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1793 	entry_time = now = hrtimer_update_base(cpu_base);
1794 retry:
1795 	cpu_base->in_hrtirq = 1;
1796 	/*
1797 	 * We set expires_next to KTIME_MAX here with cpu_base->lock
1798 	 * held to prevent that a timer is enqueued in our queue via
1799 	 * the migration code. This does not affect enqueueing of
1800 	 * timers which run their callback and need to be requeued on
1801 	 * this CPU.
1802 	 */
1803 	cpu_base->expires_next = KTIME_MAX;
1804 
1805 	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1806 		cpu_base->softirq_expires_next = KTIME_MAX;
1807 		cpu_base->softirq_activated = 1;
1808 		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1809 	}
1810 
1811 	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1812 
1813 	/* Reevaluate the clock bases for the [soft] next expiry */
1814 	expires_next = hrtimer_update_next_event(cpu_base);
1815 	/*
1816 	 * Store the new expiry value so the migration code can verify
1817 	 * against it.
1818 	 */
1819 	cpu_base->expires_next = expires_next;
1820 	cpu_base->in_hrtirq = 0;
1821 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1822 
1823 	/* Reprogramming necessary ? */
1824 	if (!tick_program_event(expires_next, 0)) {
1825 		cpu_base->hang_detected = 0;
1826 		return;
1827 	}
1828 
1829 	/*
1830 	 * The next timer was already expired due to:
1831 	 * - tracing
1832 	 * - long lasting callbacks
1833 	 * - being scheduled away when running in a VM
1834 	 *
1835 	 * We need to prevent that we loop forever in the hrtimer
1836 	 * interrupt routine. We give it 3 attempts to avoid
1837 	 * overreacting on some spurious event.
1838 	 *
1839 	 * Acquire base lock for updating the offsets and retrieving
1840 	 * the current time.
1841 	 */
1842 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1843 	now = hrtimer_update_base(cpu_base);
1844 	cpu_base->nr_retries++;
1845 	if (++retries < 3)
1846 		goto retry;
1847 	/*
1848 	 * Give the system a chance to do something else than looping
1849 	 * here. We stored the entry time, so we know exactly how long
1850 	 * we spent here. We schedule the next event this amount of
1851 	 * time away.
1852 	 */
1853 	cpu_base->nr_hangs++;
1854 	cpu_base->hang_detected = 1;
1855 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1856 
1857 	delta = ktime_sub(now, entry_time);
1858 	if ((unsigned int)delta > cpu_base->max_hang_time)
1859 		cpu_base->max_hang_time = (unsigned int) delta;
1860 	/*
1861 	 * Limit it to a sensible value as we enforce a longer
1862 	 * delay. Give the CPU at least 100ms to catch up.
1863 	 */
1864 	if (delta > 100 * NSEC_PER_MSEC)
1865 		expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1866 	else
1867 		expires_next = ktime_add(now, delta);
1868 	tick_program_event(expires_next, 1);
1869 	pr_warn_once("hrtimer: interrupt took %llu ns\n", ktime_to_ns(delta));
1870 }
1871 
1872 /* called with interrupts disabled */
__hrtimer_peek_ahead_timers(void)1873 static inline void __hrtimer_peek_ahead_timers(void)
1874 {
1875 	struct tick_device *td;
1876 
1877 	if (!hrtimer_hres_active())
1878 		return;
1879 
1880 	td = this_cpu_ptr(&tick_cpu_device);
1881 	if (td && td->evtdev)
1882 		hrtimer_interrupt(td->evtdev);
1883 }
1884 
1885 #else /* CONFIG_HIGH_RES_TIMERS */
1886 
__hrtimer_peek_ahead_timers(void)1887 static inline void __hrtimer_peek_ahead_timers(void) { }
1888 
1889 #endif	/* !CONFIG_HIGH_RES_TIMERS */
1890 
1891 /*
1892  * Called from run_local_timers in hardirq context every jiffy
1893  */
hrtimer_run_queues(void)1894 void hrtimer_run_queues(void)
1895 {
1896 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1897 	unsigned long flags;
1898 	ktime_t now;
1899 
1900 	if (__hrtimer_hres_active(cpu_base))
1901 		return;
1902 
1903 	/*
1904 	 * This _is_ ugly: We have to check periodically, whether we
1905 	 * can switch to highres and / or nohz mode. The clocksource
1906 	 * switch happens with xtime_lock held. Notification from
1907 	 * there only sets the check bit in the tick_oneshot code,
1908 	 * otherwise we might deadlock vs. xtime_lock.
1909 	 */
1910 	if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
1911 		hrtimer_switch_to_hres();
1912 		return;
1913 	}
1914 
1915 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1916 	now = hrtimer_update_base(cpu_base);
1917 
1918 	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1919 		cpu_base->softirq_expires_next = KTIME_MAX;
1920 		cpu_base->softirq_activated = 1;
1921 		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1922 	}
1923 
1924 	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1925 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1926 }
1927 
1928 /*
1929  * Sleep related functions:
1930  */
hrtimer_wakeup(struct hrtimer * timer)1931 static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1932 {
1933 	struct hrtimer_sleeper *t =
1934 		container_of(timer, struct hrtimer_sleeper, timer);
1935 	struct task_struct *task = t->task;
1936 
1937 	t->task = NULL;
1938 	if (task)
1939 		wake_up_process(task);
1940 
1941 	return HRTIMER_NORESTART;
1942 }
1943 
1944 /**
1945  * hrtimer_sleeper_start_expires - Start a hrtimer sleeper timer
1946  * @sl:		sleeper to be started
1947  * @mode:	timer mode abs/rel
1948  *
1949  * Wrapper around hrtimer_start_expires() for hrtimer_sleeper based timers
1950  * to allow PREEMPT_RT to tweak the delivery mode (soft/hardirq context)
1951  */
hrtimer_sleeper_start_expires(struct hrtimer_sleeper * sl,enum hrtimer_mode mode)1952 void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
1953 				   enum hrtimer_mode mode)
1954 {
1955 	/*
1956 	 * Make the enqueue delivery mode check work on RT. If the sleeper
1957 	 * was initialized for hard interrupt delivery, force the mode bit.
1958 	 * This is a special case for hrtimer_sleepers because
1959 	 * hrtimer_init_sleeper() determines the delivery mode on RT so the
1960 	 * fiddling with this decision is avoided at the call sites.
1961 	 */
1962 	if (IS_ENABLED(CONFIG_PREEMPT_RT) && sl->timer.is_hard)
1963 		mode |= HRTIMER_MODE_HARD;
1964 
1965 	hrtimer_start_expires(&sl->timer, mode);
1966 }
1967 EXPORT_SYMBOL_GPL(hrtimer_sleeper_start_expires);
1968 
__hrtimer_init_sleeper(struct hrtimer_sleeper * sl,clockid_t clock_id,enum hrtimer_mode mode)1969 static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
1970 				   clockid_t clock_id, enum hrtimer_mode mode)
1971 {
1972 	/*
1973 	 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1974 	 * marked for hard interrupt expiry mode are moved into soft
1975 	 * interrupt context either for latency reasons or because the
1976 	 * hrtimer callback takes regular spinlocks or invokes other
1977 	 * functions which are not suitable for hard interrupt context on
1978 	 * PREEMPT_RT.
1979 	 *
1980 	 * The hrtimer_sleeper callback is RT compatible in hard interrupt
1981 	 * context, but there is a latency concern: Untrusted userspace can
1982 	 * spawn many threads which arm timers for the same expiry time on
1983 	 * the same CPU. That causes a latency spike due to the wakeup of
1984 	 * a gazillion threads.
1985 	 *
1986 	 * OTOH, privileged real-time user space applications rely on the
1987 	 * low latency of hard interrupt wakeups. If the current task is in
1988 	 * a real-time scheduling class, mark the mode for hard interrupt
1989 	 * expiry.
1990 	 */
1991 	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
1992 		if (task_is_realtime(current) && !(mode & HRTIMER_MODE_SOFT))
1993 			mode |= HRTIMER_MODE_HARD;
1994 	}
1995 
1996 	__hrtimer_init(&sl->timer, clock_id, mode);
1997 	sl->timer.function = hrtimer_wakeup;
1998 	sl->task = current;
1999 }
2000 
2001 /**
2002  * hrtimer_init_sleeper - initialize sleeper to the given clock
2003  * @sl:		sleeper to be initialized
2004  * @clock_id:	the clock to be used
2005  * @mode:	timer mode abs/rel
2006  */
hrtimer_init_sleeper(struct hrtimer_sleeper * sl,clockid_t clock_id,enum hrtimer_mode mode)2007 void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
2008 			  enum hrtimer_mode mode)
2009 {
2010 	debug_init(&sl->timer, clock_id, mode);
2011 	__hrtimer_init_sleeper(sl, clock_id, mode);
2012 
2013 }
2014 EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
2015 
nanosleep_copyout(struct restart_block * restart,struct timespec64 * ts)2016 int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
2017 {
2018 	switch(restart->nanosleep.type) {
2019 #ifdef CONFIG_COMPAT_32BIT_TIME
2020 	case TT_COMPAT:
2021 		if (put_old_timespec32(ts, restart->nanosleep.compat_rmtp))
2022 			return -EFAULT;
2023 		break;
2024 #endif
2025 	case TT_NATIVE:
2026 		if (put_timespec64(ts, restart->nanosleep.rmtp))
2027 			return -EFAULT;
2028 		break;
2029 	default:
2030 		BUG();
2031 	}
2032 	return -ERESTART_RESTARTBLOCK;
2033 }
2034 
do_nanosleep(struct hrtimer_sleeper * t,enum hrtimer_mode mode)2035 static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
2036 {
2037 	struct restart_block *restart;
2038 
2039 	do {
2040 		set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2041 		hrtimer_sleeper_start_expires(t, mode);
2042 
2043 		if (likely(t->task))
2044 			schedule();
2045 
2046 		hrtimer_cancel(&t->timer);
2047 		mode = HRTIMER_MODE_ABS;
2048 
2049 	} while (t->task && !signal_pending(current));
2050 
2051 	__set_current_state(TASK_RUNNING);
2052 
2053 	if (!t->task)
2054 		return 0;
2055 
2056 	restart = &current->restart_block;
2057 	if (restart->nanosleep.type != TT_NONE) {
2058 		ktime_t rem = hrtimer_expires_remaining(&t->timer);
2059 		struct timespec64 rmt;
2060 
2061 		if (rem <= 0)
2062 			return 0;
2063 		rmt = ktime_to_timespec64(rem);
2064 
2065 		return nanosleep_copyout(restart, &rmt);
2066 	}
2067 	return -ERESTART_RESTARTBLOCK;
2068 }
2069 
hrtimer_nanosleep_restart(struct restart_block * restart)2070 static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
2071 {
2072 	struct hrtimer_sleeper t;
2073 	int ret;
2074 
2075 	hrtimer_init_sleeper_on_stack(&t, restart->nanosleep.clockid,
2076 				      HRTIMER_MODE_ABS);
2077 	hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
2078 	ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
2079 	destroy_hrtimer_on_stack(&t.timer);
2080 	return ret;
2081 }
2082 
hrtimer_nanosleep(ktime_t rqtp,const enum hrtimer_mode mode,const clockid_t clockid)2083 long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
2084 		       const clockid_t clockid)
2085 {
2086 	struct restart_block *restart;
2087 	struct hrtimer_sleeper t;
2088 	int ret = 0;
2089 	u64 slack;
2090 
2091 	slack = current->timer_slack_ns;
2092 	if (dl_task(current) || rt_task(current))
2093 		slack = 0;
2094 
2095 	hrtimer_init_sleeper_on_stack(&t, clockid, mode);
2096 	hrtimer_set_expires_range_ns(&t.timer, rqtp, slack);
2097 	ret = do_nanosleep(&t, mode);
2098 	if (ret != -ERESTART_RESTARTBLOCK)
2099 		goto out;
2100 
2101 	/* Absolute timers do not update the rmtp value and restart: */
2102 	if (mode == HRTIMER_MODE_ABS) {
2103 		ret = -ERESTARTNOHAND;
2104 		goto out;
2105 	}
2106 
2107 	restart = &current->restart_block;
2108 	restart->nanosleep.clockid = t.timer.base->clockid;
2109 	restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
2110 	set_restart_fn(restart, hrtimer_nanosleep_restart);
2111 out:
2112 	destroy_hrtimer_on_stack(&t.timer);
2113 	return ret;
2114 }
2115 
2116 #ifdef CONFIG_64BIT
2117 
SYSCALL_DEFINE2(nanosleep,struct __kernel_timespec __user *,rqtp,struct __kernel_timespec __user *,rmtp)2118 SYSCALL_DEFINE2(nanosleep, struct __kernel_timespec __user *, rqtp,
2119 		struct __kernel_timespec __user *, rmtp)
2120 {
2121 	struct timespec64 tu;
2122 
2123 	if (get_timespec64(&tu, rqtp))
2124 		return -EFAULT;
2125 
2126 	if (!timespec64_valid(&tu))
2127 		return -EINVAL;
2128 
2129 	current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
2130 	current->restart_block.nanosleep.rmtp = rmtp;
2131 	return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2132 				 CLOCK_MONOTONIC);
2133 }
2134 
2135 #endif
2136 
2137 #ifdef CONFIG_COMPAT_32BIT_TIME
2138 
SYSCALL_DEFINE2(nanosleep_time32,struct old_timespec32 __user *,rqtp,struct old_timespec32 __user *,rmtp)2139 SYSCALL_DEFINE2(nanosleep_time32, struct old_timespec32 __user *, rqtp,
2140 		       struct old_timespec32 __user *, rmtp)
2141 {
2142 	struct timespec64 tu;
2143 
2144 	if (get_old_timespec32(&tu, rqtp))
2145 		return -EFAULT;
2146 
2147 	if (!timespec64_valid(&tu))
2148 		return -EINVAL;
2149 
2150 	current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
2151 	current->restart_block.nanosleep.compat_rmtp = rmtp;
2152 	return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2153 				 CLOCK_MONOTONIC);
2154 }
2155 #endif
2156 
2157 /*
2158  * Functions related to boot-time initialization:
2159  */
hrtimers_prepare_cpu(unsigned int cpu)2160 int hrtimers_prepare_cpu(unsigned int cpu)
2161 {
2162 	struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
2163 	int i;
2164 
2165 	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2166 		struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i];
2167 
2168 		clock_b->cpu_base = cpu_base;
2169 		seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock);
2170 		timerqueue_init_head(&clock_b->active);
2171 	}
2172 
2173 	cpu_base->cpu = cpu;
2174 	cpu_base->active_bases = 0;
2175 	cpu_base->hres_active = 0;
2176 	cpu_base->hang_detected = 0;
2177 	cpu_base->next_timer = NULL;
2178 	cpu_base->softirq_next_timer = NULL;
2179 	cpu_base->expires_next = KTIME_MAX;
2180 	cpu_base->softirq_expires_next = KTIME_MAX;
2181 	hrtimer_cpu_base_init_expiry_lock(cpu_base);
2182 	return 0;
2183 }
2184 
2185 #ifdef CONFIG_HOTPLUG_CPU
2186 
migrate_hrtimer_list(struct hrtimer_clock_base * old_base,struct hrtimer_clock_base * new_base)2187 static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
2188 				struct hrtimer_clock_base *new_base)
2189 {
2190 	struct hrtimer *timer;
2191 	struct timerqueue_node *node;
2192 
2193 	while ((node = timerqueue_getnext(&old_base->active))) {
2194 		timer = container_of(node, struct hrtimer, node);
2195 		BUG_ON(hrtimer_callback_running(timer));
2196 		debug_deactivate(timer);
2197 
2198 		/*
2199 		 * Mark it as ENQUEUED not INACTIVE otherwise the
2200 		 * timer could be seen as !active and just vanish away
2201 		 * under us on another CPU
2202 		 */
2203 		__remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
2204 		timer->base = new_base;
2205 		/*
2206 		 * Enqueue the timers on the new cpu. This does not
2207 		 * reprogram the event device in case the timer
2208 		 * expires before the earliest on this CPU, but we run
2209 		 * hrtimer_interrupt after we migrated everything to
2210 		 * sort out already expired timers and reprogram the
2211 		 * event device.
2212 		 */
2213 		enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
2214 	}
2215 }
2216 
hrtimers_dead_cpu(unsigned int scpu)2217 int hrtimers_dead_cpu(unsigned int scpu)
2218 {
2219 	struct hrtimer_cpu_base *old_base, *new_base;
2220 	int i;
2221 
2222 	BUG_ON(cpu_online(scpu));
2223 	tick_cancel_sched_timer(scpu);
2224 
2225 	/*
2226 	 * this BH disable ensures that raise_softirq_irqoff() does
2227 	 * not wakeup ksoftirqd (and acquire the pi-lock) while
2228 	 * holding the cpu_base lock
2229 	 */
2230 	local_bh_disable();
2231 	local_irq_disable();
2232 	old_base = &per_cpu(hrtimer_bases, scpu);
2233 	new_base = this_cpu_ptr(&hrtimer_bases);
2234 	/*
2235 	 * The caller is globally serialized and nobody else
2236 	 * takes two locks at once, deadlock is not possible.
2237 	 */
2238 	raw_spin_lock(&new_base->lock);
2239 	raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
2240 
2241 	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2242 		migrate_hrtimer_list(&old_base->clock_base[i],
2243 				     &new_base->clock_base[i]);
2244 	}
2245 
2246 	/*
2247 	 * The migration might have changed the first expiring softirq
2248 	 * timer on this CPU. Update it.
2249 	 */
2250 	hrtimer_update_softirq_timer(new_base, false);
2251 
2252 	raw_spin_unlock(&old_base->lock);
2253 	raw_spin_unlock(&new_base->lock);
2254 
2255 	/* Check, if we got expired work to do */
2256 	__hrtimer_peek_ahead_timers();
2257 	local_irq_enable();
2258 	local_bh_enable();
2259 	return 0;
2260 }
2261 
2262 #endif /* CONFIG_HOTPLUG_CPU */
2263 
hrtimers_init(void)2264 void __init hrtimers_init(void)
2265 {
2266 	hrtimers_prepare_cpu(smp_processor_id());
2267 	open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
2268 }
2269 
2270 /**
2271  * schedule_hrtimeout_range_clock - sleep until timeout
2272  * @expires:	timeout value (ktime_t)
2273  * @delta:	slack in expires timeout (ktime_t)
2274  * @mode:	timer mode
2275  * @clock_id:	timer clock to be used
2276  */
2277 int __sched
schedule_hrtimeout_range_clock(ktime_t * expires,u64 delta,const enum hrtimer_mode mode,clockid_t clock_id)2278 schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
2279 			       const enum hrtimer_mode mode, clockid_t clock_id)
2280 {
2281 	struct hrtimer_sleeper t;
2282 
2283 	/*
2284 	 * Optimize when a zero timeout value is given. It does not
2285 	 * matter whether this is an absolute or a relative time.
2286 	 */
2287 	if (expires && *expires == 0) {
2288 		__set_current_state(TASK_RUNNING);
2289 		return 0;
2290 	}
2291 
2292 	/*
2293 	 * A NULL parameter means "infinite"
2294 	 */
2295 	if (!expires) {
2296 		schedule();
2297 		return -EINTR;
2298 	}
2299 
2300 	hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
2301 	hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
2302 	hrtimer_sleeper_start_expires(&t, mode);
2303 
2304 	if (likely(t.task))
2305 		schedule();
2306 
2307 	hrtimer_cancel(&t.timer);
2308 	destroy_hrtimer_on_stack(&t.timer);
2309 
2310 	__set_current_state(TASK_RUNNING);
2311 
2312 	return !t.task ? 0 : -EINTR;
2313 }
2314 EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
2315 
2316 /**
2317  * schedule_hrtimeout_range - sleep until timeout
2318  * @expires:	timeout value (ktime_t)
2319  * @delta:	slack in expires timeout (ktime_t)
2320  * @mode:	timer mode
2321  *
2322  * Make the current task sleep until the given expiry time has
2323  * elapsed. The routine will return immediately unless
2324  * the current task state has been set (see set_current_state()).
2325  *
2326  * The @delta argument gives the kernel the freedom to schedule the
2327  * actual wakeup to a time that is both power and performance friendly.
2328  * The kernel give the normal best effort behavior for "@expires+@delta",
2329  * but may decide to fire the timer earlier, but no earlier than @expires.
2330  *
2331  * You can set the task state as follows -
2332  *
2333  * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2334  * pass before the routine returns unless the current task is explicitly
2335  * woken up, (e.g. by wake_up_process()).
2336  *
2337  * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2338  * delivered to the current task or the current task is explicitly woken
2339  * up.
2340  *
2341  * The current task state is guaranteed to be TASK_RUNNING when this
2342  * routine returns.
2343  *
2344  * Returns 0 when the timer has expired. If the task was woken before the
2345  * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2346  * by an explicit wakeup, it returns -EINTR.
2347  */
schedule_hrtimeout_range(ktime_t * expires,u64 delta,const enum hrtimer_mode mode)2348 int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
2349 				     const enum hrtimer_mode mode)
2350 {
2351 	return schedule_hrtimeout_range_clock(expires, delta, mode,
2352 					      CLOCK_MONOTONIC);
2353 }
2354 EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
2355 
2356 /**
2357  * schedule_hrtimeout - sleep until timeout
2358  * @expires:	timeout value (ktime_t)
2359  * @mode:	timer mode
2360  *
2361  * Make the current task sleep until the given expiry time has
2362  * elapsed. The routine will return immediately unless
2363  * the current task state has been set (see set_current_state()).
2364  *
2365  * You can set the task state as follows -
2366  *
2367  * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2368  * pass before the routine returns unless the current task is explicitly
2369  * woken up, (e.g. by wake_up_process()).
2370  *
2371  * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2372  * delivered to the current task or the current task is explicitly woken
2373  * up.
2374  *
2375  * The current task state is guaranteed to be TASK_RUNNING when this
2376  * routine returns.
2377  *
2378  * Returns 0 when the timer has expired. If the task was woken before the
2379  * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2380  * by an explicit wakeup, it returns -EINTR.
2381  */
schedule_hrtimeout(ktime_t * expires,const enum hrtimer_mode mode)2382 int __sched schedule_hrtimeout(ktime_t *expires,
2383 			       const enum hrtimer_mode mode)
2384 {
2385 	return schedule_hrtimeout_range(expires, 0, mode);
2386 }
2387 EXPORT_SYMBOL_GPL(schedule_hrtimeout);
2388