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 	__acquires(&timer->base->lock)
168 {
169 	struct hrtimer_clock_base *base;
170 
171 	for (;;) {
172 		base = READ_ONCE(timer->base);
173 		if (likely(base != &migration_base)) {
174 			raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
175 			if (likely(base == timer->base))
176 				return base;
177 			/* The timer has migrated to another CPU: */
178 			raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
179 		}
180 		cpu_relax();
181 	}
182 }
183 
184 /*
185  * We do not migrate the timer when it is expiring before the next
186  * event on the target cpu. When high resolution is enabled, we cannot
187  * reprogram the target cpu hardware and we would cause it to fire
188  * late. To keep it simple, we handle the high resolution enabled and
189  * disabled case similar.
190  *
191  * Called with cpu_base->lock of target cpu held.
192  */
193 static int
hrtimer_check_target(struct hrtimer * timer,struct hrtimer_clock_base * new_base)194 hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
195 {
196 	ktime_t expires;
197 
198 	expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
199 	return expires < new_base->cpu_base->expires_next;
200 }
201 
202 static inline
get_target_base(struct hrtimer_cpu_base * base,int pinned)203 struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
204 					 int pinned)
205 {
206 #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
207 	if (static_branch_likely(&timers_migration_enabled) && !pinned)
208 		return &per_cpu(hrtimer_bases, get_nohz_timer_target());
209 #endif
210 	return base;
211 }
212 
213 /*
214  * We switch the timer base to a power-optimized selected CPU target,
215  * if:
216  *	- NO_HZ_COMMON is enabled
217  *	- timer migration is enabled
218  *	- the timer callback is not running
219  *	- the timer is not the first expiring timer on the new target
220  *
221  * If one of the above requirements is not fulfilled we move the timer
222  * to the current CPU or leave it on the previously assigned CPU if
223  * the timer callback is currently running.
224  */
225 static inline struct hrtimer_clock_base *
switch_hrtimer_base(struct hrtimer * timer,struct hrtimer_clock_base * base,int pinned)226 switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
227 		    int pinned)
228 {
229 	struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
230 	struct hrtimer_clock_base *new_base;
231 	int basenum = base->index;
232 
233 	this_cpu_base = this_cpu_ptr(&hrtimer_bases);
234 	new_cpu_base = get_target_base(this_cpu_base, pinned);
235 again:
236 	new_base = &new_cpu_base->clock_base[basenum];
237 
238 	if (base != new_base) {
239 		/*
240 		 * We are trying to move timer to new_base.
241 		 * However we can't change timer's base while it is running,
242 		 * so we keep it on the same CPU. No hassle vs. reprogramming
243 		 * the event source in the high resolution case. The softirq
244 		 * code will take care of this when the timer function has
245 		 * completed. There is no conflict as we hold the lock until
246 		 * the timer is enqueued.
247 		 */
248 		if (unlikely(hrtimer_callback_running(timer)))
249 			return base;
250 
251 		/* See the comment in lock_hrtimer_base() */
252 		WRITE_ONCE(timer->base, &migration_base);
253 		raw_spin_unlock(&base->cpu_base->lock);
254 		raw_spin_lock(&new_base->cpu_base->lock);
255 
256 		if (new_cpu_base != this_cpu_base &&
257 		    hrtimer_check_target(timer, new_base)) {
258 			raw_spin_unlock(&new_base->cpu_base->lock);
259 			raw_spin_lock(&base->cpu_base->lock);
260 			new_cpu_base = this_cpu_base;
261 			WRITE_ONCE(timer->base, base);
262 			goto again;
263 		}
264 		WRITE_ONCE(timer->base, new_base);
265 	} else {
266 		if (new_cpu_base != this_cpu_base &&
267 		    hrtimer_check_target(timer, new_base)) {
268 			new_cpu_base = this_cpu_base;
269 			goto again;
270 		}
271 	}
272 	return new_base;
273 }
274 
275 #else /* CONFIG_SMP */
276 
is_migration_base(struct hrtimer_clock_base * base)277 static inline bool is_migration_base(struct hrtimer_clock_base *base)
278 {
279 	return false;
280 }
281 
282 static inline struct hrtimer_clock_base *
lock_hrtimer_base(const struct hrtimer * timer,unsigned long * flags)283 lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
284 	__acquires(&timer->base->cpu_base->lock)
285 {
286 	struct hrtimer_clock_base *base = timer->base;
287 
288 	raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
289 
290 	return base;
291 }
292 
293 # define switch_hrtimer_base(t, b, p)	(b)
294 
295 #endif	/* !CONFIG_SMP */
296 
297 /*
298  * Functions for the union type storage format of ktime_t which are
299  * too large for inlining:
300  */
301 #if BITS_PER_LONG < 64
302 /*
303  * Divide a ktime value by a nanosecond value
304  */
__ktime_divns(const ktime_t kt,s64 div)305 s64 __ktime_divns(const ktime_t kt, s64 div)
306 {
307 	int sft = 0;
308 	s64 dclc;
309 	u64 tmp;
310 
311 	dclc = ktime_to_ns(kt);
312 	tmp = dclc < 0 ? -dclc : dclc;
313 
314 	/* Make sure the divisor is less than 2^32: */
315 	while (div >> 32) {
316 		sft++;
317 		div >>= 1;
318 	}
319 	tmp >>= sft;
320 	do_div(tmp, (u32) div);
321 	return dclc < 0 ? -tmp : tmp;
322 }
323 EXPORT_SYMBOL_GPL(__ktime_divns);
324 #endif /* BITS_PER_LONG >= 64 */
325 
326 /*
327  * Add two ktime values and do a safety check for overflow:
328  */
ktime_add_safe(const ktime_t lhs,const ktime_t rhs)329 ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
330 {
331 	ktime_t res = ktime_add_unsafe(lhs, rhs);
332 
333 	/*
334 	 * We use KTIME_SEC_MAX here, the maximum timeout which we can
335 	 * return to user space in a timespec:
336 	 */
337 	if (res < 0 || res < lhs || res < rhs)
338 		res = ktime_set(KTIME_SEC_MAX, 0);
339 
340 	return res;
341 }
342 
343 EXPORT_SYMBOL_GPL(ktime_add_safe);
344 
345 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
346 
347 static const struct debug_obj_descr hrtimer_debug_descr;
348 
hrtimer_debug_hint(void * addr)349 static void *hrtimer_debug_hint(void *addr)
350 {
351 	return ((struct hrtimer *) addr)->function;
352 }
353 
354 /*
355  * fixup_init is called when:
356  * - an active object is initialized
357  */
hrtimer_fixup_init(void * addr,enum debug_obj_state state)358 static bool hrtimer_fixup_init(void *addr, enum debug_obj_state state)
359 {
360 	struct hrtimer *timer = addr;
361 
362 	switch (state) {
363 	case ODEBUG_STATE_ACTIVE:
364 		hrtimer_cancel(timer);
365 		debug_object_init(timer, &hrtimer_debug_descr);
366 		return true;
367 	default:
368 		return false;
369 	}
370 }
371 
372 /*
373  * fixup_activate is called when:
374  * - an active object is activated
375  * - an unknown non-static object is activated
376  */
hrtimer_fixup_activate(void * addr,enum debug_obj_state state)377 static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
378 {
379 	switch (state) {
380 	case ODEBUG_STATE_ACTIVE:
381 		WARN_ON(1);
382 		fallthrough;
383 	default:
384 		return false;
385 	}
386 }
387 
388 /*
389  * fixup_free is called when:
390  * - an active object is freed
391  */
hrtimer_fixup_free(void * addr,enum debug_obj_state state)392 static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state)
393 {
394 	struct hrtimer *timer = addr;
395 
396 	switch (state) {
397 	case ODEBUG_STATE_ACTIVE:
398 		hrtimer_cancel(timer);
399 		debug_object_free(timer, &hrtimer_debug_descr);
400 		return true;
401 	default:
402 		return false;
403 	}
404 }
405 
406 static const struct debug_obj_descr hrtimer_debug_descr = {
407 	.name		= "hrtimer",
408 	.debug_hint	= hrtimer_debug_hint,
409 	.fixup_init	= hrtimer_fixup_init,
410 	.fixup_activate	= hrtimer_fixup_activate,
411 	.fixup_free	= hrtimer_fixup_free,
412 };
413 
debug_hrtimer_init(struct hrtimer * timer)414 static inline void debug_hrtimer_init(struct hrtimer *timer)
415 {
416 	debug_object_init(timer, &hrtimer_debug_descr);
417 }
418 
debug_hrtimer_activate(struct hrtimer * timer,enum hrtimer_mode mode)419 static inline void debug_hrtimer_activate(struct hrtimer *timer,
420 					  enum hrtimer_mode mode)
421 {
422 	debug_object_activate(timer, &hrtimer_debug_descr);
423 }
424 
debug_hrtimer_deactivate(struct hrtimer * timer)425 static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
426 {
427 	debug_object_deactivate(timer, &hrtimer_debug_descr);
428 }
429 
430 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
431 			   enum hrtimer_mode mode);
432 
hrtimer_init_on_stack(struct hrtimer * timer,clockid_t clock_id,enum hrtimer_mode mode)433 void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
434 			   enum hrtimer_mode mode)
435 {
436 	debug_object_init_on_stack(timer, &hrtimer_debug_descr);
437 	__hrtimer_init(timer, clock_id, mode);
438 }
439 EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
440 
441 static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
442 				   clockid_t clock_id, enum hrtimer_mode mode);
443 
hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper * sl,clockid_t clock_id,enum hrtimer_mode mode)444 void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
445 				   clockid_t clock_id, enum hrtimer_mode mode)
446 {
447 	debug_object_init_on_stack(&sl->timer, &hrtimer_debug_descr);
448 	__hrtimer_init_sleeper(sl, clock_id, mode);
449 }
450 EXPORT_SYMBOL_GPL(hrtimer_init_sleeper_on_stack);
451 
destroy_hrtimer_on_stack(struct hrtimer * timer)452 void destroy_hrtimer_on_stack(struct hrtimer *timer)
453 {
454 	debug_object_free(timer, &hrtimer_debug_descr);
455 }
456 EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
457 
458 #else
459 
debug_hrtimer_init(struct hrtimer * timer)460 static inline void debug_hrtimer_init(struct hrtimer *timer) { }
debug_hrtimer_activate(struct hrtimer * timer,enum hrtimer_mode mode)461 static inline void debug_hrtimer_activate(struct hrtimer *timer,
462 					  enum hrtimer_mode mode) { }
debug_hrtimer_deactivate(struct hrtimer * timer)463 static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
464 #endif
465 
466 static inline void
debug_init(struct hrtimer * timer,clockid_t clockid,enum hrtimer_mode mode)467 debug_init(struct hrtimer *timer, clockid_t clockid,
468 	   enum hrtimer_mode mode)
469 {
470 	debug_hrtimer_init(timer);
471 	trace_hrtimer_init(timer, clockid, mode);
472 }
473 
debug_activate(struct hrtimer * timer,enum hrtimer_mode mode)474 static inline void debug_activate(struct hrtimer *timer,
475 				  enum hrtimer_mode mode)
476 {
477 	debug_hrtimer_activate(timer, mode);
478 	trace_hrtimer_start(timer, mode);
479 }
480 
debug_deactivate(struct hrtimer * timer)481 static inline void debug_deactivate(struct hrtimer *timer)
482 {
483 	debug_hrtimer_deactivate(timer);
484 	trace_hrtimer_cancel(timer);
485 }
486 
487 static struct hrtimer_clock_base *
__next_base(struct hrtimer_cpu_base * cpu_base,unsigned int * active)488 __next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
489 {
490 	unsigned int idx;
491 
492 	if (!*active)
493 		return NULL;
494 
495 	idx = __ffs(*active);
496 	*active &= ~(1U << idx);
497 
498 	return &cpu_base->clock_base[idx];
499 }
500 
501 #define for_each_active_base(base, cpu_base, active)	\
502 	while ((base = __next_base((cpu_base), &(active))))
503 
__hrtimer_next_event_base(struct hrtimer_cpu_base * cpu_base,const struct hrtimer * exclude,unsigned int active,ktime_t expires_next)504 static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
505 					 const struct hrtimer *exclude,
506 					 unsigned int active,
507 					 ktime_t expires_next)
508 {
509 	struct hrtimer_clock_base *base;
510 	ktime_t expires;
511 
512 	for_each_active_base(base, cpu_base, active) {
513 		struct timerqueue_node *next;
514 		struct hrtimer *timer;
515 
516 		next = timerqueue_getnext(&base->active);
517 		timer = container_of(next, struct hrtimer, node);
518 		if (timer == exclude) {
519 			/* Get to the next timer in the queue. */
520 			next = timerqueue_iterate_next(next);
521 			if (!next)
522 				continue;
523 
524 			timer = container_of(next, struct hrtimer, node);
525 		}
526 		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
527 		if (expires < expires_next) {
528 			expires_next = expires;
529 
530 			/* Skip cpu_base update if a timer is being excluded. */
531 			if (exclude)
532 				continue;
533 
534 			if (timer->is_soft)
535 				cpu_base->softirq_next_timer = timer;
536 			else
537 				cpu_base->next_timer = timer;
538 		}
539 	}
540 	/*
541 	 * clock_was_set() might have changed base->offset of any of
542 	 * the clock bases so the result might be negative. Fix it up
543 	 * to prevent a false positive in clockevents_program_event().
544 	 */
545 	if (expires_next < 0)
546 		expires_next = 0;
547 	return expires_next;
548 }
549 
550 /*
551  * Recomputes cpu_base::*next_timer and returns the earliest expires_next
552  * but does not set cpu_base::*expires_next, that is done by
553  * hrtimer[_force]_reprogram and hrtimer_interrupt only. When updating
554  * cpu_base::*expires_next right away, reprogramming logic would no longer
555  * work.
556  *
557  * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
558  * those timers will get run whenever the softirq gets handled, at the end of
559  * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
560  *
561  * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
562  * The !softirq values are the minima across HRTIMER_ACTIVE_ALL, unless an actual
563  * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
564  *
565  * @active_mask must be one of:
566  *  - HRTIMER_ACTIVE_ALL,
567  *  - HRTIMER_ACTIVE_SOFT, or
568  *  - HRTIMER_ACTIVE_HARD.
569  */
570 static ktime_t
__hrtimer_get_next_event(struct hrtimer_cpu_base * cpu_base,unsigned int active_mask)571 __hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
572 {
573 	unsigned int active;
574 	struct hrtimer *next_timer = NULL;
575 	ktime_t expires_next = KTIME_MAX;
576 
577 	if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
578 		active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
579 		cpu_base->softirq_next_timer = NULL;
580 		expires_next = __hrtimer_next_event_base(cpu_base, NULL,
581 							 active, KTIME_MAX);
582 
583 		next_timer = cpu_base->softirq_next_timer;
584 	}
585 
586 	if (active_mask & HRTIMER_ACTIVE_HARD) {
587 		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
588 		cpu_base->next_timer = next_timer;
589 		expires_next = __hrtimer_next_event_base(cpu_base, NULL, active,
590 							 expires_next);
591 	}
592 
593 	return expires_next;
594 }
595 
hrtimer_update_next_event(struct hrtimer_cpu_base * cpu_base)596 static ktime_t hrtimer_update_next_event(struct hrtimer_cpu_base *cpu_base)
597 {
598 	ktime_t expires_next, soft = KTIME_MAX;
599 
600 	/*
601 	 * If the soft interrupt has already been activated, ignore the
602 	 * soft bases. They will be handled in the already raised soft
603 	 * interrupt.
604 	 */
605 	if (!cpu_base->softirq_activated) {
606 		soft = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
607 		/*
608 		 * Update the soft expiry time. clock_settime() might have
609 		 * affected it.
610 		 */
611 		cpu_base->softirq_expires_next = soft;
612 	}
613 
614 	expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
615 	/*
616 	 * If a softirq timer is expiring first, update cpu_base->next_timer
617 	 * and program the hardware with the soft expiry time.
618 	 */
619 	if (expires_next > soft) {
620 		cpu_base->next_timer = cpu_base->softirq_next_timer;
621 		expires_next = soft;
622 	}
623 
624 	return expires_next;
625 }
626 
hrtimer_update_base(struct hrtimer_cpu_base * base)627 static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
628 {
629 	ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
630 	ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
631 	ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
632 
633 	ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
634 					    offs_real, offs_boot, offs_tai);
635 
636 	base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
637 	base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
638 	base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
639 
640 	return now;
641 }
642 
643 /*
644  * Is the high resolution mode active ?
645  */
__hrtimer_hres_active(struct hrtimer_cpu_base * cpu_base)646 static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
647 {
648 	return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
649 		cpu_base->hres_active : 0;
650 }
651 
hrtimer_hres_active(void)652 static inline int hrtimer_hres_active(void)
653 {
654 	return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
655 }
656 
__hrtimer_reprogram(struct hrtimer_cpu_base * cpu_base,struct hrtimer * next_timer,ktime_t expires_next)657 static void __hrtimer_reprogram(struct hrtimer_cpu_base *cpu_base,
658 				struct hrtimer *next_timer,
659 				ktime_t expires_next)
660 {
661 	cpu_base->expires_next = expires_next;
662 
663 	/*
664 	 * If hres is not active, hardware does not have to be
665 	 * reprogrammed yet.
666 	 *
667 	 * If a hang was detected in the last timer interrupt then we
668 	 * leave the hang delay active in the hardware. We want the
669 	 * system to make progress. That also prevents the following
670 	 * scenario:
671 	 * T1 expires 50ms from now
672 	 * T2 expires 5s from now
673 	 *
674 	 * T1 is removed, so this code is called and would reprogram
675 	 * the hardware to 5s from now. Any hrtimer_start after that
676 	 * will not reprogram the hardware due to hang_detected being
677 	 * set. So we'd effectively block all timers until the T2 event
678 	 * fires.
679 	 */
680 	if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
681 		return;
682 
683 	tick_program_event(expires_next, 1);
684 }
685 
686 /*
687  * Reprogram the event source with checking both queues for the
688  * next event
689  * Called with interrupts disabled and base->lock held
690  */
691 static void
hrtimer_force_reprogram(struct hrtimer_cpu_base * cpu_base,int skip_equal)692 hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
693 {
694 	ktime_t expires_next;
695 
696 	expires_next = hrtimer_update_next_event(cpu_base);
697 
698 	if (skip_equal && expires_next == cpu_base->expires_next)
699 		return;
700 
701 	__hrtimer_reprogram(cpu_base, cpu_base->next_timer, expires_next);
702 }
703 
704 /* High resolution timer related functions */
705 #ifdef CONFIG_HIGH_RES_TIMERS
706 
707 /*
708  * High resolution timer enabled ?
709  */
710 static bool hrtimer_hres_enabled __read_mostly  = true;
711 unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
712 EXPORT_SYMBOL_GPL(hrtimer_resolution);
713 
714 /*
715  * Enable / Disable high resolution mode
716  */
setup_hrtimer_hres(char * str)717 static int __init setup_hrtimer_hres(char *str)
718 {
719 	return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
720 }
721 
722 __setup("highres=", setup_hrtimer_hres);
723 
724 /*
725  * hrtimer_high_res_enabled - query, if the highres mode is enabled
726  */
hrtimer_is_hres_enabled(void)727 static inline int hrtimer_is_hres_enabled(void)
728 {
729 	return hrtimer_hres_enabled;
730 }
731 
732 static void retrigger_next_event(void *arg);
733 
734 /*
735  * Switch to high resolution mode
736  */
hrtimer_switch_to_hres(void)737 static void hrtimer_switch_to_hres(void)
738 {
739 	struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
740 
741 	if (tick_init_highres()) {
742 		pr_warn("Could not switch to high resolution mode on CPU %u\n",
743 			base->cpu);
744 		return;
745 	}
746 	base->hres_active = 1;
747 	hrtimer_resolution = HIGH_RES_NSEC;
748 
749 	tick_setup_sched_timer();
750 	/* "Retrigger" the interrupt to get things going */
751 	retrigger_next_event(NULL);
752 }
753 
754 #else
755 
hrtimer_is_hres_enabled(void)756 static inline int hrtimer_is_hres_enabled(void) { return 0; }
hrtimer_switch_to_hres(void)757 static inline void hrtimer_switch_to_hres(void) { }
758 
759 #endif /* CONFIG_HIGH_RES_TIMERS */
760 /*
761  * Retrigger next event is called after clock was set with interrupts
762  * disabled through an SMP function call or directly from low level
763  * resume code.
764  *
765  * This is only invoked when:
766  *	- CONFIG_HIGH_RES_TIMERS is enabled.
767  *	- CONFIG_NOHZ_COMMON is enabled
768  *
769  * For the other cases this function is empty and because the call sites
770  * are optimized out it vanishes as well, i.e. no need for lots of
771  * #ifdeffery.
772  */
retrigger_next_event(void * arg)773 static void retrigger_next_event(void *arg)
774 {
775 	struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
776 
777 	/*
778 	 * When high resolution mode or nohz is active, then the offsets of
779 	 * CLOCK_REALTIME/TAI/BOOTTIME have to be updated. Otherwise the
780 	 * next tick will take care of that.
781 	 *
782 	 * If high resolution mode is active then the next expiring timer
783 	 * must be reevaluated and the clock event device reprogrammed if
784 	 * necessary.
785 	 *
786 	 * In the NOHZ case the update of the offset and the reevaluation
787 	 * of the next expiring timer is enough. The return from the SMP
788 	 * function call will take care of the reprogramming in case the
789 	 * CPU was in a NOHZ idle sleep.
790 	 */
791 	if (!__hrtimer_hres_active(base) && !tick_nohz_active)
792 		return;
793 
794 	raw_spin_lock(&base->lock);
795 	hrtimer_update_base(base);
796 	if (__hrtimer_hres_active(base))
797 		hrtimer_force_reprogram(base, 0);
798 	else
799 		hrtimer_update_next_event(base);
800 	raw_spin_unlock(&base->lock);
801 }
802 
803 /*
804  * When a timer is enqueued and expires earlier than the already enqueued
805  * timers, we have to check, whether it expires earlier than the timer for
806  * which the clock event device was armed.
807  *
808  * Called with interrupts disabled and base->cpu_base.lock held
809  */
hrtimer_reprogram(struct hrtimer * timer,bool reprogram)810 static void hrtimer_reprogram(struct hrtimer *timer, bool reprogram)
811 {
812 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
813 	struct hrtimer_clock_base *base = timer->base;
814 	ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
815 
816 	WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
817 
818 	/*
819 	 * CLOCK_REALTIME timer might be requested with an absolute
820 	 * expiry time which is less than base->offset. Set it to 0.
821 	 */
822 	if (expires < 0)
823 		expires = 0;
824 
825 	if (timer->is_soft) {
826 		/*
827 		 * soft hrtimer could be started on a remote CPU. In this
828 		 * case softirq_expires_next needs to be updated on the
829 		 * remote CPU. The soft hrtimer will not expire before the
830 		 * first hard hrtimer on the remote CPU -
831 		 * hrtimer_check_target() prevents this case.
832 		 */
833 		struct hrtimer_cpu_base *timer_cpu_base = base->cpu_base;
834 
835 		if (timer_cpu_base->softirq_activated)
836 			return;
837 
838 		if (!ktime_before(expires, timer_cpu_base->softirq_expires_next))
839 			return;
840 
841 		timer_cpu_base->softirq_next_timer = timer;
842 		timer_cpu_base->softirq_expires_next = expires;
843 
844 		if (!ktime_before(expires, timer_cpu_base->expires_next) ||
845 		    !reprogram)
846 			return;
847 	}
848 
849 	/*
850 	 * If the timer is not on the current cpu, we cannot reprogram
851 	 * the other cpus clock event device.
852 	 */
853 	if (base->cpu_base != cpu_base)
854 		return;
855 
856 	if (expires >= cpu_base->expires_next)
857 		return;
858 
859 	/*
860 	 * If the hrtimer interrupt is running, then it will reevaluate the
861 	 * clock bases and reprogram the clock event device.
862 	 */
863 	if (cpu_base->in_hrtirq)
864 		return;
865 
866 	cpu_base->next_timer = timer;
867 
868 	__hrtimer_reprogram(cpu_base, timer, expires);
869 }
870 
update_needs_ipi(struct hrtimer_cpu_base * cpu_base,unsigned int active)871 static bool update_needs_ipi(struct hrtimer_cpu_base *cpu_base,
872 			     unsigned int active)
873 {
874 	struct hrtimer_clock_base *base;
875 	unsigned int seq;
876 	ktime_t expires;
877 
878 	/*
879 	 * Update the base offsets unconditionally so the following
880 	 * checks whether the SMP function call is required works.
881 	 *
882 	 * The update is safe even when the remote CPU is in the hrtimer
883 	 * interrupt or the hrtimer soft interrupt and expiring affected
884 	 * bases. Either it will see the update before handling a base or
885 	 * it will see it when it finishes the processing and reevaluates
886 	 * the next expiring timer.
887 	 */
888 	seq = cpu_base->clock_was_set_seq;
889 	hrtimer_update_base(cpu_base);
890 
891 	/*
892 	 * If the sequence did not change over the update then the
893 	 * remote CPU already handled it.
894 	 */
895 	if (seq == cpu_base->clock_was_set_seq)
896 		return false;
897 
898 	/*
899 	 * If the remote CPU is currently handling an hrtimer interrupt, it
900 	 * will reevaluate the first expiring timer of all clock bases
901 	 * before reprogramming. Nothing to do here.
902 	 */
903 	if (cpu_base->in_hrtirq)
904 		return false;
905 
906 	/*
907 	 * Walk the affected clock bases and check whether the first expiring
908 	 * timer in a clock base is moving ahead of the first expiring timer of
909 	 * @cpu_base. If so, the IPI must be invoked because per CPU clock
910 	 * event devices cannot be remotely reprogrammed.
911 	 */
912 	active &= cpu_base->active_bases;
913 
914 	for_each_active_base(base, cpu_base, active) {
915 		struct timerqueue_node *next;
916 
917 		next = timerqueue_getnext(&base->active);
918 		expires = ktime_sub(next->expires, base->offset);
919 		if (expires < cpu_base->expires_next)
920 			return true;
921 
922 		/* Extra check for softirq clock bases */
923 		if (base->clockid < HRTIMER_BASE_MONOTONIC_SOFT)
924 			continue;
925 		if (cpu_base->softirq_activated)
926 			continue;
927 		if (expires < cpu_base->softirq_expires_next)
928 			return true;
929 	}
930 	return false;
931 }
932 
933 /*
934  * Clock was set. This might affect CLOCK_REALTIME, CLOCK_TAI and
935  * CLOCK_BOOTTIME (for late sleep time injection).
936  *
937  * This requires to update the offsets for these clocks
938  * vs. CLOCK_MONOTONIC. When high resolution timers are enabled, then this
939  * also requires to eventually reprogram the per CPU clock event devices
940  * when the change moves an affected timer ahead of the first expiring
941  * timer on that CPU. Obviously remote per CPU clock event devices cannot
942  * be reprogrammed. The other reason why an IPI has to be sent is when the
943  * system is in !HIGH_RES and NOHZ mode. The NOHZ mode updates the offsets
944  * in the tick, which obviously might be stopped, so this has to bring out
945  * the remote CPU which might sleep in idle to get this sorted.
946  */
clock_was_set(unsigned int bases)947 void clock_was_set(unsigned int bases)
948 {
949 	struct hrtimer_cpu_base *cpu_base = raw_cpu_ptr(&hrtimer_bases);
950 	cpumask_var_t mask;
951 	int cpu;
952 
953 	if (!__hrtimer_hres_active(cpu_base) && !tick_nohz_active)
954 		goto out_timerfd;
955 
956 	if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
957 		on_each_cpu(retrigger_next_event, NULL, 1);
958 		goto out_timerfd;
959 	}
960 
961 	/* Avoid interrupting CPUs if possible */
962 	cpus_read_lock();
963 	for_each_online_cpu(cpu) {
964 		unsigned long flags;
965 
966 		cpu_base = &per_cpu(hrtimer_bases, cpu);
967 		raw_spin_lock_irqsave(&cpu_base->lock, flags);
968 
969 		if (update_needs_ipi(cpu_base, bases))
970 			cpumask_set_cpu(cpu, mask);
971 
972 		raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
973 	}
974 
975 	preempt_disable();
976 	smp_call_function_many(mask, retrigger_next_event, NULL, 1);
977 	preempt_enable();
978 	cpus_read_unlock();
979 	free_cpumask_var(mask);
980 
981 out_timerfd:
982 	timerfd_clock_was_set();
983 }
984 
clock_was_set_work(struct work_struct * work)985 static void clock_was_set_work(struct work_struct *work)
986 {
987 	clock_was_set(CLOCK_SET_WALL);
988 }
989 
990 static DECLARE_WORK(hrtimer_work, clock_was_set_work);
991 
992 /*
993  * Called from timekeeping code to reprogram the hrtimer interrupt device
994  * on all cpus and to notify timerfd.
995  */
clock_was_set_delayed(void)996 void clock_was_set_delayed(void)
997 {
998 	schedule_work(&hrtimer_work);
999 }
1000 
1001 /*
1002  * Called during resume either directly from via timekeeping_resume()
1003  * or in the case of s2idle from tick_unfreeze() to ensure that the
1004  * hrtimers are up to date.
1005  */
hrtimers_resume_local(void)1006 void hrtimers_resume_local(void)
1007 {
1008 	lockdep_assert_irqs_disabled();
1009 	/* Retrigger on the local CPU */
1010 	retrigger_next_event(NULL);
1011 }
1012 
1013 /*
1014  * Counterpart to lock_hrtimer_base above:
1015  */
1016 static inline
unlock_hrtimer_base(const struct hrtimer * timer,unsigned long * flags)1017 void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
1018 	__releases(&timer->base->cpu_base->lock)
1019 {
1020 	raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
1021 }
1022 
1023 /**
1024  * hrtimer_forward - forward the timer expiry
1025  * @timer:	hrtimer to forward
1026  * @now:	forward past this time
1027  * @interval:	the interval to forward
1028  *
1029  * Forward the timer expiry so it will expire in the future.
1030  * Returns the number of overruns.
1031  *
1032  * Can be safely called from the callback function of @timer. If
1033  * called from other contexts @timer must neither be enqueued nor
1034  * running the callback and the caller needs to take care of
1035  * serialization.
1036  *
1037  * Note: This only updates the timer expiry value and does not requeue
1038  * the timer.
1039  */
hrtimer_forward(struct hrtimer * timer,ktime_t now,ktime_t interval)1040 u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
1041 {
1042 	u64 orun = 1;
1043 	ktime_t delta;
1044 
1045 	delta = ktime_sub(now, hrtimer_get_expires(timer));
1046 
1047 	if (delta < 0)
1048 		return 0;
1049 
1050 	if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
1051 		return 0;
1052 
1053 	if (interval < hrtimer_resolution)
1054 		interval = hrtimer_resolution;
1055 
1056 	if (unlikely(delta >= interval)) {
1057 		s64 incr = ktime_to_ns(interval);
1058 
1059 		orun = ktime_divns(delta, incr);
1060 		hrtimer_add_expires_ns(timer, incr * orun);
1061 		if (hrtimer_get_expires_tv64(timer) > now)
1062 			return orun;
1063 		/*
1064 		 * This (and the ktime_add() below) is the
1065 		 * correction for exact:
1066 		 */
1067 		orun++;
1068 	}
1069 	hrtimer_add_expires(timer, interval);
1070 
1071 	return orun;
1072 }
1073 EXPORT_SYMBOL_GPL(hrtimer_forward);
1074 
1075 /*
1076  * enqueue_hrtimer - internal function to (re)start a timer
1077  *
1078  * The timer is inserted in expiry order. Insertion into the
1079  * red black tree is O(log(n)). Must hold the base lock.
1080  *
1081  * Returns 1 when the new timer is the leftmost timer in the tree.
1082  */
enqueue_hrtimer(struct hrtimer * timer,struct hrtimer_clock_base * base,enum hrtimer_mode mode)1083 static int enqueue_hrtimer(struct hrtimer *timer,
1084 			   struct hrtimer_clock_base *base,
1085 			   enum hrtimer_mode mode)
1086 {
1087 	debug_activate(timer, mode);
1088 	WARN_ON_ONCE(!base->cpu_base->online);
1089 
1090 	base->cpu_base->active_bases |= 1 << base->index;
1091 
1092 	/* Pairs with the lockless read in hrtimer_is_queued() */
1093 	WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
1094 
1095 	return timerqueue_add(&base->active, &timer->node);
1096 }
1097 
1098 /*
1099  * __remove_hrtimer - internal function to remove a timer
1100  *
1101  * Caller must hold the base lock.
1102  *
1103  * High resolution timer mode reprograms the clock event device when the
1104  * timer is the one which expires next. The caller can disable this by setting
1105  * reprogram to zero. This is useful, when the context does a reprogramming
1106  * anyway (e.g. timer interrupt)
1107  */
__remove_hrtimer(struct hrtimer * timer,struct hrtimer_clock_base * base,u8 newstate,int reprogram)1108 static void __remove_hrtimer(struct hrtimer *timer,
1109 			     struct hrtimer_clock_base *base,
1110 			     u8 newstate, int reprogram)
1111 {
1112 	struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1113 	u8 state = timer->state;
1114 
1115 	/* Pairs with the lockless read in hrtimer_is_queued() */
1116 	WRITE_ONCE(timer->state, newstate);
1117 	if (!(state & HRTIMER_STATE_ENQUEUED))
1118 		return;
1119 
1120 	if (!timerqueue_del(&base->active, &timer->node))
1121 		cpu_base->active_bases &= ~(1 << base->index);
1122 
1123 	/*
1124 	 * Note: If reprogram is false we do not update
1125 	 * cpu_base->next_timer. This happens when we remove the first
1126 	 * timer on a remote cpu. No harm as we never dereference
1127 	 * cpu_base->next_timer. So the worst thing what can happen is
1128 	 * an superfluous call to hrtimer_force_reprogram() on the
1129 	 * remote cpu later on if the same timer gets enqueued again.
1130 	 */
1131 	if (reprogram && timer == cpu_base->next_timer)
1132 		hrtimer_force_reprogram(cpu_base, 1);
1133 }
1134 
1135 /*
1136  * remove hrtimer, called with base lock held
1137  */
1138 static inline int
remove_hrtimer(struct hrtimer * timer,struct hrtimer_clock_base * base,bool restart,bool keep_local)1139 remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base,
1140 	       bool restart, bool keep_local)
1141 {
1142 	u8 state = timer->state;
1143 
1144 	if (state & HRTIMER_STATE_ENQUEUED) {
1145 		bool reprogram;
1146 
1147 		/*
1148 		 * Remove the timer and force reprogramming when high
1149 		 * resolution mode is active and the timer is on the current
1150 		 * CPU. If we remove a timer on another CPU, reprogramming is
1151 		 * skipped. The interrupt event on this CPU is fired and
1152 		 * reprogramming happens in the interrupt handler. This is a
1153 		 * rare case and less expensive than a smp call.
1154 		 */
1155 		debug_deactivate(timer);
1156 		reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1157 
1158 		/*
1159 		 * If the timer is not restarted then reprogramming is
1160 		 * required if the timer is local. If it is local and about
1161 		 * to be restarted, avoid programming it twice (on removal
1162 		 * and a moment later when it's requeued).
1163 		 */
1164 		if (!restart)
1165 			state = HRTIMER_STATE_INACTIVE;
1166 		else
1167 			reprogram &= !keep_local;
1168 
1169 		__remove_hrtimer(timer, base, state, reprogram);
1170 		return 1;
1171 	}
1172 	return 0;
1173 }
1174 
hrtimer_update_lowres(struct hrtimer * timer,ktime_t tim,const enum hrtimer_mode mode)1175 static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
1176 					    const enum hrtimer_mode mode)
1177 {
1178 #ifdef CONFIG_TIME_LOW_RES
1179 	/*
1180 	 * CONFIG_TIME_LOW_RES indicates that the system has no way to return
1181 	 * granular time values. For relative timers we add hrtimer_resolution
1182 	 * (i.e. one jiffie) to prevent short timeouts.
1183 	 */
1184 	timer->is_rel = mode & HRTIMER_MODE_REL;
1185 	if (timer->is_rel)
1186 		tim = ktime_add_safe(tim, hrtimer_resolution);
1187 #endif
1188 	return tim;
1189 }
1190 
1191 static void
hrtimer_update_softirq_timer(struct hrtimer_cpu_base * cpu_base,bool reprogram)1192 hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
1193 {
1194 	ktime_t expires;
1195 
1196 	/*
1197 	 * Find the next SOFT expiration.
1198 	 */
1199 	expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
1200 
1201 	/*
1202 	 * reprogramming needs to be triggered, even if the next soft
1203 	 * hrtimer expires at the same time than the next hard
1204 	 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
1205 	 */
1206 	if (expires == KTIME_MAX)
1207 		return;
1208 
1209 	/*
1210 	 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
1211 	 * cpu_base->*expires_next is only set by hrtimer_reprogram()
1212 	 */
1213 	hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
1214 }
1215 
__hrtimer_start_range_ns(struct hrtimer * timer,ktime_t tim,u64 delta_ns,const enum hrtimer_mode mode,struct hrtimer_clock_base * base)1216 static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1217 				    u64 delta_ns, const enum hrtimer_mode mode,
1218 				    struct hrtimer_clock_base *base)
1219 {
1220 	struct hrtimer_clock_base *new_base;
1221 	bool force_local, first;
1222 
1223 	/*
1224 	 * If the timer is on the local cpu base and is the first expiring
1225 	 * timer then this might end up reprogramming the hardware twice
1226 	 * (on removal and on enqueue). To avoid that by prevent the
1227 	 * reprogram on removal, keep the timer local to the current CPU
1228 	 * and enforce reprogramming after it is queued no matter whether
1229 	 * it is the new first expiring timer again or not.
1230 	 */
1231 	force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1232 	force_local &= base->cpu_base->next_timer == timer;
1233 
1234 	/*
1235 	 * Remove an active timer from the queue. In case it is not queued
1236 	 * on the current CPU, make sure that remove_hrtimer() updates the
1237 	 * remote data correctly.
1238 	 *
1239 	 * If it's on the current CPU and the first expiring timer, then
1240 	 * skip reprogramming, keep the timer local and enforce
1241 	 * reprogramming later if it was the first expiring timer.  This
1242 	 * avoids programming the underlying clock event twice (once at
1243 	 * removal and once after enqueue).
1244 	 */
1245 	remove_hrtimer(timer, base, true, force_local);
1246 
1247 	if (mode & HRTIMER_MODE_REL)
1248 		tim = ktime_add_safe(tim, base->get_time());
1249 
1250 	tim = hrtimer_update_lowres(timer, tim, mode);
1251 
1252 	hrtimer_set_expires_range_ns(timer, tim, delta_ns);
1253 
1254 	/* Switch the timer base, if necessary: */
1255 	if (!force_local) {
1256 		new_base = switch_hrtimer_base(timer, base,
1257 					       mode & HRTIMER_MODE_PINNED);
1258 	} else {
1259 		new_base = base;
1260 	}
1261 
1262 	first = enqueue_hrtimer(timer, new_base, mode);
1263 	if (!force_local)
1264 		return first;
1265 
1266 	/*
1267 	 * Timer was forced to stay on the current CPU to avoid
1268 	 * reprogramming on removal and enqueue. Force reprogram the
1269 	 * hardware by evaluating the new first expiring timer.
1270 	 */
1271 	hrtimer_force_reprogram(new_base->cpu_base, 1);
1272 	return 0;
1273 }
1274 
1275 /**
1276  * hrtimer_start_range_ns - (re)start an hrtimer
1277  * @timer:	the timer to be added
1278  * @tim:	expiry time
1279  * @delta_ns:	"slack" range for the timer
1280  * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
1281  *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
1282  *		softirq based mode is considered for debug purpose only!
1283  */
hrtimer_start_range_ns(struct hrtimer * timer,ktime_t tim,u64 delta_ns,const enum hrtimer_mode mode)1284 void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1285 			    u64 delta_ns, const enum hrtimer_mode mode)
1286 {
1287 	struct hrtimer_clock_base *base;
1288 	unsigned long flags;
1289 
1290 	/*
1291 	 * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
1292 	 * match on CONFIG_PREEMPT_RT = n. With PREEMPT_RT check the hard
1293 	 * expiry mode because unmarked timers are moved to softirq expiry.
1294 	 */
1295 	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
1296 		WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
1297 	else
1298 		WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard);
1299 
1300 	base = lock_hrtimer_base(timer, &flags);
1301 
1302 	if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
1303 		hrtimer_reprogram(timer, true);
1304 
1305 	unlock_hrtimer_base(timer, &flags);
1306 }
1307 EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1308 
1309 /**
1310  * hrtimer_try_to_cancel - try to deactivate a timer
1311  * @timer:	hrtimer to stop
1312  *
1313  * Returns:
1314  *
1315  *  *  0 when the timer was not active
1316  *  *  1 when the timer was active
1317  *  * -1 when the timer is currently executing the callback function and
1318  *    cannot be stopped
1319  */
hrtimer_try_to_cancel(struct hrtimer * timer)1320 int hrtimer_try_to_cancel(struct hrtimer *timer)
1321 {
1322 	struct hrtimer_clock_base *base;
1323 	unsigned long flags;
1324 	int ret = -1;
1325 
1326 	/*
1327 	 * Check lockless first. If the timer is not active (neither
1328 	 * enqueued nor running the callback, nothing to do here.  The
1329 	 * base lock does not serialize against a concurrent enqueue,
1330 	 * so we can avoid taking it.
1331 	 */
1332 	if (!hrtimer_active(timer))
1333 		return 0;
1334 
1335 	base = lock_hrtimer_base(timer, &flags);
1336 
1337 	if (!hrtimer_callback_running(timer))
1338 		ret = remove_hrtimer(timer, base, false, false);
1339 
1340 	unlock_hrtimer_base(timer, &flags);
1341 
1342 	return ret;
1343 
1344 }
1345 EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1346 
1347 #ifdef CONFIG_PREEMPT_RT
hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base * base)1348 static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
1349 {
1350 	spin_lock_init(&base->softirq_expiry_lock);
1351 }
1352 
hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base * base)1353 static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
1354 {
1355 	spin_lock(&base->softirq_expiry_lock);
1356 }
1357 
hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base * base)1358 static void hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base)
1359 {
1360 	spin_unlock(&base->softirq_expiry_lock);
1361 }
1362 
1363 /*
1364  * The counterpart to hrtimer_cancel_wait_running().
1365  *
1366  * If there is a waiter for cpu_base->expiry_lock, then it was waiting for
1367  * the timer callback to finish. Drop expiry_lock and reacquire it. That
1368  * allows the waiter to acquire the lock and make progress.
1369  */
hrtimer_sync_wait_running(struct hrtimer_cpu_base * cpu_base,unsigned long flags)1370 static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base,
1371 				      unsigned long flags)
1372 {
1373 	if (atomic_read(&cpu_base->timer_waiters)) {
1374 		raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1375 		spin_unlock(&cpu_base->softirq_expiry_lock);
1376 		spin_lock(&cpu_base->softirq_expiry_lock);
1377 		raw_spin_lock_irq(&cpu_base->lock);
1378 	}
1379 }
1380 
1381 /*
1382  * This function is called on PREEMPT_RT kernels when the fast path
1383  * deletion of a timer failed because the timer callback function was
1384  * running.
1385  *
1386  * This prevents priority inversion: if the soft irq thread is preempted
1387  * in the middle of a timer callback, then calling del_timer_sync() can
1388  * lead to two issues:
1389  *
1390  *  - If the caller is on a remote CPU then it has to spin wait for the timer
1391  *    handler to complete. This can result in unbound priority inversion.
1392  *
1393  *  - If the caller originates from the task which preempted the timer
1394  *    handler on the same CPU, then spin waiting for the timer handler to
1395  *    complete is never going to end.
1396  */
hrtimer_cancel_wait_running(const struct hrtimer * timer)1397 void hrtimer_cancel_wait_running(const struct hrtimer *timer)
1398 {
1399 	/* Lockless read. Prevent the compiler from reloading it below */
1400 	struct hrtimer_clock_base *base = READ_ONCE(timer->base);
1401 
1402 	/*
1403 	 * Just relax if the timer expires in hard interrupt context or if
1404 	 * it is currently on the migration base.
1405 	 */
1406 	if (!timer->is_soft || is_migration_base(base)) {
1407 		cpu_relax();
1408 		return;
1409 	}
1410 
1411 	/*
1412 	 * Mark the base as contended and grab the expiry lock, which is
1413 	 * held by the softirq across the timer callback. Drop the lock
1414 	 * immediately so the softirq can expire the next timer. In theory
1415 	 * the timer could already be running again, but that's more than
1416 	 * unlikely and just causes another wait loop.
1417 	 */
1418 	atomic_inc(&base->cpu_base->timer_waiters);
1419 	spin_lock_bh(&base->cpu_base->softirq_expiry_lock);
1420 	atomic_dec(&base->cpu_base->timer_waiters);
1421 	spin_unlock_bh(&base->cpu_base->softirq_expiry_lock);
1422 }
1423 #else
1424 static inline void
hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base * base)1425 hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
1426 static inline void
hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base * base)1427 hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
1428 static inline void
hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base * base)1429 hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
hrtimer_sync_wait_running(struct hrtimer_cpu_base * base,unsigned long flags)1430 static inline void hrtimer_sync_wait_running(struct hrtimer_cpu_base *base,
1431 					     unsigned long flags) { }
1432 #endif
1433 
1434 /**
1435  * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1436  * @timer:	the timer to be cancelled
1437  *
1438  * Returns:
1439  *  0 when the timer was not active
1440  *  1 when the timer was active
1441  */
hrtimer_cancel(struct hrtimer * timer)1442 int hrtimer_cancel(struct hrtimer *timer)
1443 {
1444 	int ret;
1445 
1446 	do {
1447 		ret = hrtimer_try_to_cancel(timer);
1448 
1449 		if (ret < 0)
1450 			hrtimer_cancel_wait_running(timer);
1451 	} while (ret < 0);
1452 	return ret;
1453 }
1454 EXPORT_SYMBOL_GPL(hrtimer_cancel);
1455 
1456 /**
1457  * __hrtimer_get_remaining - get remaining time for the timer
1458  * @timer:	the timer to read
1459  * @adjust:	adjust relative timers when CONFIG_TIME_LOW_RES=y
1460  */
__hrtimer_get_remaining(const struct hrtimer * timer,bool adjust)1461 ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
1462 {
1463 	unsigned long flags;
1464 	ktime_t rem;
1465 
1466 	lock_hrtimer_base(timer, &flags);
1467 	if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
1468 		rem = hrtimer_expires_remaining_adjusted(timer);
1469 	else
1470 		rem = hrtimer_expires_remaining(timer);
1471 	unlock_hrtimer_base(timer, &flags);
1472 
1473 	return rem;
1474 }
1475 EXPORT_SYMBOL_GPL(__hrtimer_get_remaining);
1476 
1477 #ifdef CONFIG_NO_HZ_COMMON
1478 /**
1479  * hrtimer_get_next_event - get the time until next expiry event
1480  *
1481  * Returns the next expiry time or KTIME_MAX if no timer is pending.
1482  */
hrtimer_get_next_event(void)1483 u64 hrtimer_get_next_event(void)
1484 {
1485 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1486 	u64 expires = KTIME_MAX;
1487 	unsigned long flags;
1488 
1489 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1490 
1491 	if (!__hrtimer_hres_active(cpu_base))
1492 		expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
1493 
1494 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1495 
1496 	return expires;
1497 }
1498 
1499 /**
1500  * hrtimer_next_event_without - time until next expiry event w/o one timer
1501  * @exclude:	timer to exclude
1502  *
1503  * Returns the next expiry time over all timers except for the @exclude one or
1504  * KTIME_MAX if none of them is pending.
1505  */
hrtimer_next_event_without(const struct hrtimer * exclude)1506 u64 hrtimer_next_event_without(const struct hrtimer *exclude)
1507 {
1508 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1509 	u64 expires = KTIME_MAX;
1510 	unsigned long flags;
1511 
1512 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1513 
1514 	if (__hrtimer_hres_active(cpu_base)) {
1515 		unsigned int active;
1516 
1517 		if (!cpu_base->softirq_activated) {
1518 			active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
1519 			expires = __hrtimer_next_event_base(cpu_base, exclude,
1520 							    active, KTIME_MAX);
1521 		}
1522 		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
1523 		expires = __hrtimer_next_event_base(cpu_base, exclude, active,
1524 						    expires);
1525 	}
1526 
1527 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1528 
1529 	return expires;
1530 }
1531 #endif
1532 
hrtimer_clockid_to_base(clockid_t clock_id)1533 static inline int hrtimer_clockid_to_base(clockid_t clock_id)
1534 {
1535 	if (likely(clock_id < MAX_CLOCKS)) {
1536 		int base = hrtimer_clock_to_base_table[clock_id];
1537 
1538 		if (likely(base != HRTIMER_MAX_CLOCK_BASES))
1539 			return base;
1540 	}
1541 	WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
1542 	return HRTIMER_BASE_MONOTONIC;
1543 }
1544 
__hrtimer_init(struct hrtimer * timer,clockid_t clock_id,enum hrtimer_mode mode)1545 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1546 			   enum hrtimer_mode mode)
1547 {
1548 	bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
1549 	struct hrtimer_cpu_base *cpu_base;
1550 	int base;
1551 
1552 	/*
1553 	 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1554 	 * marked for hard interrupt expiry mode are moved into soft
1555 	 * interrupt context for latency reasons and because the callbacks
1556 	 * can invoke functions which might sleep on RT, e.g. spin_lock().
1557 	 */
1558 	if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD))
1559 		softtimer = true;
1560 
1561 	memset(timer, 0, sizeof(struct hrtimer));
1562 
1563 	cpu_base = raw_cpu_ptr(&hrtimer_bases);
1564 
1565 	/*
1566 	 * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
1567 	 * clock modifications, so they needs to become CLOCK_MONOTONIC to
1568 	 * ensure POSIX compliance.
1569 	 */
1570 	if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
1571 		clock_id = CLOCK_MONOTONIC;
1572 
1573 	base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
1574 	base += hrtimer_clockid_to_base(clock_id);
1575 	timer->is_soft = softtimer;
1576 	timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
1577 	timer->base = &cpu_base->clock_base[base];
1578 	timerqueue_init(&timer->node);
1579 }
1580 
1581 /**
1582  * hrtimer_init - initialize a timer to the given clock
1583  * @timer:	the timer to be initialized
1584  * @clock_id:	the clock to be used
1585  * @mode:       The modes which are relevant for initialization:
1586  *              HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
1587  *              HRTIMER_MODE_REL_SOFT
1588  *
1589  *              The PINNED variants of the above can be handed in,
1590  *              but the PINNED bit is ignored as pinning happens
1591  *              when the hrtimer is started
1592  */
hrtimer_init(struct hrtimer * timer,clockid_t clock_id,enum hrtimer_mode mode)1593 void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1594 		  enum hrtimer_mode mode)
1595 {
1596 	debug_init(timer, clock_id, mode);
1597 	__hrtimer_init(timer, clock_id, mode);
1598 }
1599 EXPORT_SYMBOL_GPL(hrtimer_init);
1600 
1601 /*
1602  * A timer is active, when it is enqueued into the rbtree or the
1603  * callback function is running or it's in the state of being migrated
1604  * to another cpu.
1605  *
1606  * It is important for this function to not return a false negative.
1607  */
hrtimer_active(const struct hrtimer * timer)1608 bool hrtimer_active(const struct hrtimer *timer)
1609 {
1610 	struct hrtimer_clock_base *base;
1611 	unsigned int seq;
1612 
1613 	do {
1614 		base = READ_ONCE(timer->base);
1615 		seq = raw_read_seqcount_begin(&base->seq);
1616 
1617 		if (timer->state != HRTIMER_STATE_INACTIVE ||
1618 		    base->running == timer)
1619 			return true;
1620 
1621 	} while (read_seqcount_retry(&base->seq, seq) ||
1622 		 base != READ_ONCE(timer->base));
1623 
1624 	return false;
1625 }
1626 EXPORT_SYMBOL_GPL(hrtimer_active);
1627 
1628 /*
1629  * The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
1630  * distinct sections:
1631  *
1632  *  - queued:	the timer is queued
1633  *  - callback:	the timer is being ran
1634  *  - post:	the timer is inactive or (re)queued
1635  *
1636  * On the read side we ensure we observe timer->state and cpu_base->running
1637  * from the same section, if anything changed while we looked at it, we retry.
1638  * This includes timer->base changing because sequence numbers alone are
1639  * insufficient for that.
1640  *
1641  * The sequence numbers are required because otherwise we could still observe
1642  * a false negative if the read side got smeared over multiple consecutive
1643  * __run_hrtimer() invocations.
1644  */
1645 
__run_hrtimer(struct hrtimer_cpu_base * cpu_base,struct hrtimer_clock_base * base,struct hrtimer * timer,ktime_t * now,unsigned long flags)1646 static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
1647 			  struct hrtimer_clock_base *base,
1648 			  struct hrtimer *timer, ktime_t *now,
1649 			  unsigned long flags) __must_hold(&cpu_base->lock)
1650 {
1651 	enum hrtimer_restart (*fn)(struct hrtimer *);
1652 	bool expires_in_hardirq;
1653 	int restart;
1654 
1655 	lockdep_assert_held(&cpu_base->lock);
1656 
1657 	debug_deactivate(timer);
1658 	base->running = timer;
1659 
1660 	/*
1661 	 * Separate the ->running assignment from the ->state assignment.
1662 	 *
1663 	 * As with a regular write barrier, this ensures the read side in
1664 	 * hrtimer_active() cannot observe base->running == NULL &&
1665 	 * timer->state == INACTIVE.
1666 	 */
1667 	raw_write_seqcount_barrier(&base->seq);
1668 
1669 	__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
1670 	fn = timer->function;
1671 
1672 	/*
1673 	 * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
1674 	 * timer is restarted with a period then it becomes an absolute
1675 	 * timer. If its not restarted it does not matter.
1676 	 */
1677 	if (IS_ENABLED(CONFIG_TIME_LOW_RES))
1678 		timer->is_rel = false;
1679 
1680 	/*
1681 	 * The timer is marked as running in the CPU base, so it is
1682 	 * protected against migration to a different CPU even if the lock
1683 	 * is dropped.
1684 	 */
1685 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1686 	trace_hrtimer_expire_entry(timer, now);
1687 	expires_in_hardirq = lockdep_hrtimer_enter(timer);
1688 
1689 	restart = fn(timer);
1690 
1691 	lockdep_hrtimer_exit(expires_in_hardirq);
1692 	trace_hrtimer_expire_exit(timer);
1693 	raw_spin_lock_irq(&cpu_base->lock);
1694 
1695 	/*
1696 	 * Note: We clear the running state after enqueue_hrtimer and
1697 	 * we do not reprogram the event hardware. Happens either in
1698 	 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1699 	 *
1700 	 * Note: Because we dropped the cpu_base->lock above,
1701 	 * hrtimer_start_range_ns() can have popped in and enqueued the timer
1702 	 * for us already.
1703 	 */
1704 	if (restart != HRTIMER_NORESTART &&
1705 	    !(timer->state & HRTIMER_STATE_ENQUEUED))
1706 		enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
1707 
1708 	/*
1709 	 * Separate the ->running assignment from the ->state assignment.
1710 	 *
1711 	 * As with a regular write barrier, this ensures the read side in
1712 	 * hrtimer_active() cannot observe base->running.timer == NULL &&
1713 	 * timer->state == INACTIVE.
1714 	 */
1715 	raw_write_seqcount_barrier(&base->seq);
1716 
1717 	WARN_ON_ONCE(base->running != timer);
1718 	base->running = NULL;
1719 }
1720 
__hrtimer_run_queues(struct hrtimer_cpu_base * cpu_base,ktime_t now,unsigned long flags,unsigned int active_mask)1721 static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
1722 				 unsigned long flags, unsigned int active_mask)
1723 {
1724 	struct hrtimer_clock_base *base;
1725 	unsigned int active = cpu_base->active_bases & active_mask;
1726 
1727 	for_each_active_base(base, cpu_base, active) {
1728 		struct timerqueue_node *node;
1729 		ktime_t basenow;
1730 
1731 		basenow = ktime_add(now, base->offset);
1732 
1733 		while ((node = timerqueue_getnext(&base->active))) {
1734 			struct hrtimer *timer;
1735 
1736 			timer = container_of(node, struct hrtimer, node);
1737 
1738 			/*
1739 			 * The immediate goal for using the softexpires is
1740 			 * minimizing wakeups, not running timers at the
1741 			 * earliest interrupt after their soft expiration.
1742 			 * This allows us to avoid using a Priority Search
1743 			 * Tree, which can answer a stabbing query for
1744 			 * overlapping intervals and instead use the simple
1745 			 * BST we already have.
1746 			 * We don't add extra wakeups by delaying timers that
1747 			 * are right-of a not yet expired timer, because that
1748 			 * timer will have to trigger a wakeup anyway.
1749 			 */
1750 			if (basenow < hrtimer_get_softexpires_tv64(timer))
1751 				break;
1752 
1753 			__run_hrtimer(cpu_base, base, timer, &basenow, flags);
1754 			if (active_mask == HRTIMER_ACTIVE_SOFT)
1755 				hrtimer_sync_wait_running(cpu_base, flags);
1756 		}
1757 	}
1758 }
1759 
hrtimer_run_softirq(struct softirq_action * h)1760 static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
1761 {
1762 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1763 	unsigned long flags;
1764 	ktime_t now;
1765 
1766 	hrtimer_cpu_base_lock_expiry(cpu_base);
1767 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1768 
1769 	now = hrtimer_update_base(cpu_base);
1770 	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
1771 
1772 	cpu_base->softirq_activated = 0;
1773 	hrtimer_update_softirq_timer(cpu_base, true);
1774 
1775 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1776 	hrtimer_cpu_base_unlock_expiry(cpu_base);
1777 }
1778 
1779 #ifdef CONFIG_HIGH_RES_TIMERS
1780 
1781 /*
1782  * High resolution timer interrupt
1783  * Called with interrupts disabled
1784  */
hrtimer_interrupt(struct clock_event_device * dev)1785 void hrtimer_interrupt(struct clock_event_device *dev)
1786 {
1787 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1788 	ktime_t expires_next, now, entry_time, delta;
1789 	unsigned long flags;
1790 	int retries = 0;
1791 
1792 	BUG_ON(!cpu_base->hres_active);
1793 	cpu_base->nr_events++;
1794 	dev->next_event = KTIME_MAX;
1795 
1796 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1797 	entry_time = now = hrtimer_update_base(cpu_base);
1798 retry:
1799 	cpu_base->in_hrtirq = 1;
1800 	/*
1801 	 * We set expires_next to KTIME_MAX here with cpu_base->lock
1802 	 * held to prevent that a timer is enqueued in our queue via
1803 	 * the migration code. This does not affect enqueueing of
1804 	 * timers which run their callback and need to be requeued on
1805 	 * this CPU.
1806 	 */
1807 	cpu_base->expires_next = KTIME_MAX;
1808 
1809 	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1810 		cpu_base->softirq_expires_next = KTIME_MAX;
1811 		cpu_base->softirq_activated = 1;
1812 		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1813 	}
1814 
1815 	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1816 
1817 	/* Reevaluate the clock bases for the [soft] next expiry */
1818 	expires_next = hrtimer_update_next_event(cpu_base);
1819 	/*
1820 	 * Store the new expiry value so the migration code can verify
1821 	 * against it.
1822 	 */
1823 	cpu_base->expires_next = expires_next;
1824 	cpu_base->in_hrtirq = 0;
1825 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1826 
1827 	/* Reprogramming necessary ? */
1828 	if (!tick_program_event(expires_next, 0)) {
1829 		cpu_base->hang_detected = 0;
1830 		return;
1831 	}
1832 
1833 	/*
1834 	 * The next timer was already expired due to:
1835 	 * - tracing
1836 	 * - long lasting callbacks
1837 	 * - being scheduled away when running in a VM
1838 	 *
1839 	 * We need to prevent that we loop forever in the hrtimer
1840 	 * interrupt routine. We give it 3 attempts to avoid
1841 	 * overreacting on some spurious event.
1842 	 *
1843 	 * Acquire base lock for updating the offsets and retrieving
1844 	 * the current time.
1845 	 */
1846 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1847 	now = hrtimer_update_base(cpu_base);
1848 	cpu_base->nr_retries++;
1849 	if (++retries < 3)
1850 		goto retry;
1851 	/*
1852 	 * Give the system a chance to do something else than looping
1853 	 * here. We stored the entry time, so we know exactly how long
1854 	 * we spent here. We schedule the next event this amount of
1855 	 * time away.
1856 	 */
1857 	cpu_base->nr_hangs++;
1858 	cpu_base->hang_detected = 1;
1859 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1860 
1861 	delta = ktime_sub(now, entry_time);
1862 	if ((unsigned int)delta > cpu_base->max_hang_time)
1863 		cpu_base->max_hang_time = (unsigned int) delta;
1864 	/*
1865 	 * Limit it to a sensible value as we enforce a longer
1866 	 * delay. Give the CPU at least 100ms to catch up.
1867 	 */
1868 	if (delta > 100 * NSEC_PER_MSEC)
1869 		expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1870 	else
1871 		expires_next = ktime_add(now, delta);
1872 	tick_program_event(expires_next, 1);
1873 	pr_warn_once("hrtimer: interrupt took %llu ns\n", ktime_to_ns(delta));
1874 }
1875 
1876 /* called with interrupts disabled */
__hrtimer_peek_ahead_timers(void)1877 static inline void __hrtimer_peek_ahead_timers(void)
1878 {
1879 	struct tick_device *td;
1880 
1881 	if (!hrtimer_hres_active())
1882 		return;
1883 
1884 	td = this_cpu_ptr(&tick_cpu_device);
1885 	if (td && td->evtdev)
1886 		hrtimer_interrupt(td->evtdev);
1887 }
1888 
1889 #else /* CONFIG_HIGH_RES_TIMERS */
1890 
__hrtimer_peek_ahead_timers(void)1891 static inline void __hrtimer_peek_ahead_timers(void) { }
1892 
1893 #endif	/* !CONFIG_HIGH_RES_TIMERS */
1894 
1895 /*
1896  * Called from run_local_timers in hardirq context every jiffy
1897  */
hrtimer_run_queues(void)1898 void hrtimer_run_queues(void)
1899 {
1900 	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1901 	unsigned long flags;
1902 	ktime_t now;
1903 
1904 	if (__hrtimer_hres_active(cpu_base))
1905 		return;
1906 
1907 	/*
1908 	 * This _is_ ugly: We have to check periodically, whether we
1909 	 * can switch to highres and / or nohz mode. The clocksource
1910 	 * switch happens with xtime_lock held. Notification from
1911 	 * there only sets the check bit in the tick_oneshot code,
1912 	 * otherwise we might deadlock vs. xtime_lock.
1913 	 */
1914 	if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
1915 		hrtimer_switch_to_hres();
1916 		return;
1917 	}
1918 
1919 	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1920 	now = hrtimer_update_base(cpu_base);
1921 
1922 	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1923 		cpu_base->softirq_expires_next = KTIME_MAX;
1924 		cpu_base->softirq_activated = 1;
1925 		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1926 	}
1927 
1928 	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1929 	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1930 }
1931 
1932 /*
1933  * Sleep related functions:
1934  */
hrtimer_wakeup(struct hrtimer * timer)1935 static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1936 {
1937 	struct hrtimer_sleeper *t =
1938 		container_of(timer, struct hrtimer_sleeper, timer);
1939 	struct task_struct *task = t->task;
1940 
1941 	t->task = NULL;
1942 	if (task)
1943 		wake_up_process(task);
1944 
1945 	return HRTIMER_NORESTART;
1946 }
1947 
1948 /**
1949  * hrtimer_sleeper_start_expires - Start a hrtimer sleeper timer
1950  * @sl:		sleeper to be started
1951  * @mode:	timer mode abs/rel
1952  *
1953  * Wrapper around hrtimer_start_expires() for hrtimer_sleeper based timers
1954  * to allow PREEMPT_RT to tweak the delivery mode (soft/hardirq context)
1955  */
hrtimer_sleeper_start_expires(struct hrtimer_sleeper * sl,enum hrtimer_mode mode)1956 void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
1957 				   enum hrtimer_mode mode)
1958 {
1959 	/*
1960 	 * Make the enqueue delivery mode check work on RT. If the sleeper
1961 	 * was initialized for hard interrupt delivery, force the mode bit.
1962 	 * This is a special case for hrtimer_sleepers because
1963 	 * hrtimer_init_sleeper() determines the delivery mode on RT so the
1964 	 * fiddling with this decision is avoided at the call sites.
1965 	 */
1966 	if (IS_ENABLED(CONFIG_PREEMPT_RT) && sl->timer.is_hard)
1967 		mode |= HRTIMER_MODE_HARD;
1968 
1969 	hrtimer_start_expires(&sl->timer, mode);
1970 }
1971 EXPORT_SYMBOL_GPL(hrtimer_sleeper_start_expires);
1972 
__hrtimer_init_sleeper(struct hrtimer_sleeper * sl,clockid_t clock_id,enum hrtimer_mode mode)1973 static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
1974 				   clockid_t clock_id, enum hrtimer_mode mode)
1975 {
1976 	/*
1977 	 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1978 	 * marked for hard interrupt expiry mode are moved into soft
1979 	 * interrupt context either for latency reasons or because the
1980 	 * hrtimer callback takes regular spinlocks or invokes other
1981 	 * functions which are not suitable for hard interrupt context on
1982 	 * PREEMPT_RT.
1983 	 *
1984 	 * The hrtimer_sleeper callback is RT compatible in hard interrupt
1985 	 * context, but there is a latency concern: Untrusted userspace can
1986 	 * spawn many threads which arm timers for the same expiry time on
1987 	 * the same CPU. That causes a latency spike due to the wakeup of
1988 	 * a gazillion threads.
1989 	 *
1990 	 * OTOH, privileged real-time user space applications rely on the
1991 	 * low latency of hard interrupt wakeups. If the current task is in
1992 	 * a real-time scheduling class, mark the mode for hard interrupt
1993 	 * expiry.
1994 	 */
1995 	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
1996 		if (task_is_realtime(current) && !(mode & HRTIMER_MODE_SOFT))
1997 			mode |= HRTIMER_MODE_HARD;
1998 	}
1999 
2000 	__hrtimer_init(&sl->timer, clock_id, mode);
2001 	sl->timer.function = hrtimer_wakeup;
2002 	sl->task = current;
2003 }
2004 
2005 /**
2006  * hrtimer_init_sleeper - initialize sleeper to the given clock
2007  * @sl:		sleeper to be initialized
2008  * @clock_id:	the clock to be used
2009  * @mode:	timer mode abs/rel
2010  */
hrtimer_init_sleeper(struct hrtimer_sleeper * sl,clockid_t clock_id,enum hrtimer_mode mode)2011 void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
2012 			  enum hrtimer_mode mode)
2013 {
2014 	debug_init(&sl->timer, clock_id, mode);
2015 	__hrtimer_init_sleeper(sl, clock_id, mode);
2016 
2017 }
2018 EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
2019 
nanosleep_copyout(struct restart_block * restart,struct timespec64 * ts)2020 int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
2021 {
2022 	switch(restart->nanosleep.type) {
2023 #ifdef CONFIG_COMPAT_32BIT_TIME
2024 	case TT_COMPAT:
2025 		if (put_old_timespec32(ts, restart->nanosleep.compat_rmtp))
2026 			return -EFAULT;
2027 		break;
2028 #endif
2029 	case TT_NATIVE:
2030 		if (put_timespec64(ts, restart->nanosleep.rmtp))
2031 			return -EFAULT;
2032 		break;
2033 	default:
2034 		BUG();
2035 	}
2036 	return -ERESTART_RESTARTBLOCK;
2037 }
2038 
do_nanosleep(struct hrtimer_sleeper * t,enum hrtimer_mode mode)2039 static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
2040 {
2041 	struct restart_block *restart;
2042 
2043 	do {
2044 		set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2045 		hrtimer_sleeper_start_expires(t, mode);
2046 
2047 		if (likely(t->task))
2048 			schedule();
2049 
2050 		hrtimer_cancel(&t->timer);
2051 		mode = HRTIMER_MODE_ABS;
2052 
2053 	} while (t->task && !signal_pending(current));
2054 
2055 	__set_current_state(TASK_RUNNING);
2056 
2057 	if (!t->task)
2058 		return 0;
2059 
2060 	restart = &current->restart_block;
2061 	if (restart->nanosleep.type != TT_NONE) {
2062 		ktime_t rem = hrtimer_expires_remaining(&t->timer);
2063 		struct timespec64 rmt;
2064 
2065 		if (rem <= 0)
2066 			return 0;
2067 		rmt = ktime_to_timespec64(rem);
2068 
2069 		return nanosleep_copyout(restart, &rmt);
2070 	}
2071 	return -ERESTART_RESTARTBLOCK;
2072 }
2073 
hrtimer_nanosleep_restart(struct restart_block * restart)2074 static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
2075 {
2076 	struct hrtimer_sleeper t;
2077 	int ret;
2078 
2079 	hrtimer_init_sleeper_on_stack(&t, restart->nanosleep.clockid,
2080 				      HRTIMER_MODE_ABS);
2081 	hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
2082 	ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
2083 	destroy_hrtimer_on_stack(&t.timer);
2084 	return ret;
2085 }
2086 
hrtimer_nanosleep(ktime_t rqtp,const enum hrtimer_mode mode,const clockid_t clockid)2087 long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
2088 		       const clockid_t clockid)
2089 {
2090 	struct restart_block *restart;
2091 	struct hrtimer_sleeper t;
2092 	int ret = 0;
2093 	u64 slack;
2094 
2095 	slack = current->timer_slack_ns;
2096 	if (rt_task(current))
2097 		slack = 0;
2098 
2099 	hrtimer_init_sleeper_on_stack(&t, clockid, mode);
2100 	hrtimer_set_expires_range_ns(&t.timer, rqtp, slack);
2101 	ret = do_nanosleep(&t, mode);
2102 	if (ret != -ERESTART_RESTARTBLOCK)
2103 		goto out;
2104 
2105 	/* Absolute timers do not update the rmtp value and restart: */
2106 	if (mode == HRTIMER_MODE_ABS) {
2107 		ret = -ERESTARTNOHAND;
2108 		goto out;
2109 	}
2110 
2111 	restart = &current->restart_block;
2112 	restart->nanosleep.clockid = t.timer.base->clockid;
2113 	restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
2114 	set_restart_fn(restart, hrtimer_nanosleep_restart);
2115 out:
2116 	destroy_hrtimer_on_stack(&t.timer);
2117 	return ret;
2118 }
2119 
2120 #ifdef CONFIG_64BIT
2121 
SYSCALL_DEFINE2(nanosleep,struct __kernel_timespec __user *,rqtp,struct __kernel_timespec __user *,rmtp)2122 SYSCALL_DEFINE2(nanosleep, struct __kernel_timespec __user *, rqtp,
2123 		struct __kernel_timespec __user *, rmtp)
2124 {
2125 	struct timespec64 tu;
2126 
2127 	if (get_timespec64(&tu, rqtp))
2128 		return -EFAULT;
2129 
2130 	if (!timespec64_valid(&tu))
2131 		return -EINVAL;
2132 
2133 	current->restart_block.fn = do_no_restart_syscall;
2134 	current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
2135 	current->restart_block.nanosleep.rmtp = rmtp;
2136 	return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2137 				 CLOCK_MONOTONIC);
2138 }
2139 
2140 #endif
2141 
2142 #ifdef CONFIG_COMPAT_32BIT_TIME
2143 
SYSCALL_DEFINE2(nanosleep_time32,struct old_timespec32 __user *,rqtp,struct old_timespec32 __user *,rmtp)2144 SYSCALL_DEFINE2(nanosleep_time32, struct old_timespec32 __user *, rqtp,
2145 		       struct old_timespec32 __user *, rmtp)
2146 {
2147 	struct timespec64 tu;
2148 
2149 	if (get_old_timespec32(&tu, rqtp))
2150 		return -EFAULT;
2151 
2152 	if (!timespec64_valid(&tu))
2153 		return -EINVAL;
2154 
2155 	current->restart_block.fn = do_no_restart_syscall;
2156 	current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
2157 	current->restart_block.nanosleep.compat_rmtp = rmtp;
2158 	return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2159 				 CLOCK_MONOTONIC);
2160 }
2161 #endif
2162 
2163 /*
2164  * Functions related to boot-time initialization:
2165  */
hrtimers_prepare_cpu(unsigned int cpu)2166 int hrtimers_prepare_cpu(unsigned int cpu)
2167 {
2168 	struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
2169 	int i;
2170 
2171 	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2172 		struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i];
2173 
2174 		clock_b->cpu_base = cpu_base;
2175 		seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock);
2176 		timerqueue_init_head(&clock_b->active);
2177 	}
2178 
2179 	cpu_base->cpu = cpu;
2180 	cpu_base->active_bases = 0;
2181 	cpu_base->hres_active = 0;
2182 	cpu_base->hang_detected = 0;
2183 	cpu_base->next_timer = NULL;
2184 	cpu_base->softirq_next_timer = NULL;
2185 	cpu_base->expires_next = KTIME_MAX;
2186 	cpu_base->softirq_expires_next = KTIME_MAX;
2187 	cpu_base->online = 1;
2188 	hrtimer_cpu_base_init_expiry_lock(cpu_base);
2189 	return 0;
2190 }
2191 
2192 #ifdef CONFIG_HOTPLUG_CPU
2193 
migrate_hrtimer_list(struct hrtimer_clock_base * old_base,struct hrtimer_clock_base * new_base)2194 static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
2195 				struct hrtimer_clock_base *new_base)
2196 {
2197 	struct hrtimer *timer;
2198 	struct timerqueue_node *node;
2199 
2200 	while ((node = timerqueue_getnext(&old_base->active))) {
2201 		timer = container_of(node, struct hrtimer, node);
2202 		BUG_ON(hrtimer_callback_running(timer));
2203 		debug_deactivate(timer);
2204 
2205 		/*
2206 		 * Mark it as ENQUEUED not INACTIVE otherwise the
2207 		 * timer could be seen as !active and just vanish away
2208 		 * under us on another CPU
2209 		 */
2210 		__remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
2211 		timer->base = new_base;
2212 		/*
2213 		 * Enqueue the timers on the new cpu. This does not
2214 		 * reprogram the event device in case the timer
2215 		 * expires before the earliest on this CPU, but we run
2216 		 * hrtimer_interrupt after we migrated everything to
2217 		 * sort out already expired timers and reprogram the
2218 		 * event device.
2219 		 */
2220 		enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
2221 	}
2222 }
2223 
hrtimers_cpu_dying(unsigned int dying_cpu)2224 int hrtimers_cpu_dying(unsigned int dying_cpu)
2225 {
2226 	struct hrtimer_cpu_base *old_base, *new_base;
2227 	int i, ncpu = cpumask_first(cpu_active_mask);
2228 
2229 	tick_cancel_sched_timer(dying_cpu);
2230 
2231 	old_base = this_cpu_ptr(&hrtimer_bases);
2232 	new_base = &per_cpu(hrtimer_bases, ncpu);
2233 
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(&old_base->lock);
2239 	raw_spin_lock_nested(&new_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_get_next_event(new_base, HRTIMER_ACTIVE_SOFT);
2251 	/* Tell the other CPU to retrigger the next event */
2252 	smp_call_function_single(ncpu, retrigger_next_event, NULL, 0);
2253 
2254 	raw_spin_unlock(&new_base->lock);
2255 	old_base->online = 0;
2256 	raw_spin_unlock(&old_base->lock);
2257 
2258 	return 0;
2259 }
2260 
2261 #endif /* CONFIG_HOTPLUG_CPU */
2262 
hrtimers_init(void)2263 void __init hrtimers_init(void)
2264 {
2265 	hrtimers_prepare_cpu(smp_processor_id());
2266 	open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
2267 }
2268 
2269 /**
2270  * schedule_hrtimeout_range_clock - sleep until timeout
2271  * @expires:	timeout value (ktime_t)
2272  * @delta:	slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2273  * @mode:	timer mode
2274  * @clock_id:	timer clock to be used
2275  */
2276 int __sched
schedule_hrtimeout_range_clock(ktime_t * expires,u64 delta,const enum hrtimer_mode mode,clockid_t clock_id)2277 schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
2278 			       const enum hrtimer_mode mode, clockid_t clock_id)
2279 {
2280 	struct hrtimer_sleeper t;
2281 
2282 	/*
2283 	 * Optimize when a zero timeout value is given. It does not
2284 	 * matter whether this is an absolute or a relative time.
2285 	 */
2286 	if (expires && *expires == 0) {
2287 		__set_current_state(TASK_RUNNING);
2288 		return 0;
2289 	}
2290 
2291 	/*
2292 	 * A NULL parameter means "infinite"
2293 	 */
2294 	if (!expires) {
2295 		schedule();
2296 		return -EINTR;
2297 	}
2298 
2299 	/*
2300 	 * Override any slack passed by the user if under
2301 	 * rt contraints.
2302 	 */
2303 	if (rt_task(current))
2304 		delta = 0;
2305 
2306 	hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
2307 	hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
2308 	hrtimer_sleeper_start_expires(&t, mode);
2309 
2310 	if (likely(t.task))
2311 		schedule();
2312 
2313 	hrtimer_cancel(&t.timer);
2314 	destroy_hrtimer_on_stack(&t.timer);
2315 
2316 	__set_current_state(TASK_RUNNING);
2317 
2318 	return !t.task ? 0 : -EINTR;
2319 }
2320 EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
2321 
2322 /**
2323  * schedule_hrtimeout_range - sleep until timeout
2324  * @expires:	timeout value (ktime_t)
2325  * @delta:	slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2326  * @mode:	timer mode
2327  *
2328  * Make the current task sleep until the given expiry time has
2329  * elapsed. The routine will return immediately unless
2330  * the current task state has been set (see set_current_state()).
2331  *
2332  * The @delta argument gives the kernel the freedom to schedule the
2333  * actual wakeup to a time that is both power and performance friendly
2334  * for regular (non RT/DL) tasks.
2335  * The kernel give the normal best effort behavior for "@expires+@delta",
2336  * but may decide to fire the timer earlier, but no earlier than @expires.
2337  *
2338  * You can set the task state as follows -
2339  *
2340  * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2341  * pass before the routine returns unless the current task is explicitly
2342  * woken up, (e.g. by wake_up_process()).
2343  *
2344  * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2345  * delivered to the current task or the current task is explicitly woken
2346  * up.
2347  *
2348  * The current task state is guaranteed to be TASK_RUNNING when this
2349  * routine returns.
2350  *
2351  * Returns 0 when the timer has expired. If the task was woken before the
2352  * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2353  * by an explicit wakeup, it returns -EINTR.
2354  */
schedule_hrtimeout_range(ktime_t * expires,u64 delta,const enum hrtimer_mode mode)2355 int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
2356 				     const enum hrtimer_mode mode)
2357 {
2358 	return schedule_hrtimeout_range_clock(expires, delta, mode,
2359 					      CLOCK_MONOTONIC);
2360 }
2361 EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
2362 
2363 /**
2364  * schedule_hrtimeout - sleep until timeout
2365  * @expires:	timeout value (ktime_t)
2366  * @mode:	timer mode
2367  *
2368  * Make the current task sleep until the given expiry time has
2369  * elapsed. The routine will return immediately unless
2370  * the current task state has been set (see set_current_state()).
2371  *
2372  * You can set the task state as follows -
2373  *
2374  * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2375  * pass before the routine returns unless the current task is explicitly
2376  * woken up, (e.g. by wake_up_process()).
2377  *
2378  * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2379  * delivered to the current task or the current task is explicitly woken
2380  * up.
2381  *
2382  * The current task state is guaranteed to be TASK_RUNNING when this
2383  * routine returns.
2384  *
2385  * Returns 0 when the timer has expired. If the task was woken before the
2386  * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2387  * by an explicit wakeup, it returns -EINTR.
2388  */
schedule_hrtimeout(ktime_t * expires,const enum hrtimer_mode mode)2389 int __sched schedule_hrtimeout(ktime_t *expires,
2390 			       const enum hrtimer_mode mode)
2391 {
2392 	return schedule_hrtimeout_range(expires, 0, mode);
2393 }
2394 EXPORT_SYMBOL_GPL(schedule_hrtimeout);
2395