1/*
   2 *  linux/kernel/hrtimer.c
   3 *
   4 *  Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
   5 *  Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
   6 *  Copyright(C) 2006-2007  Timesys Corp., Thomas Gleixner
   7 *
   8 *  High-resolution kernel timers
   9 *
  10 *  In contrast to the low-resolution timeout API implemented in
  11 *  kernel/timer.c, hrtimers provide finer resolution and accuracy
  12 *  depending on system configuration and capabilities.
  13 *
  14 *  These timers are currently used for:
  15 *   - itimers
  16 *   - POSIX timers
  17 *   - nanosleep
  18 *   - precise in-kernel timing
  19 *
  20 *  Started by: Thomas Gleixner and Ingo Molnar
  21 *
  22 *  Credits:
  23 *	based on kernel/timer.c
  24 *
  25 *	Help, testing, suggestions, bugfixes, improvements were
  26 *	provided by:
  27 *
  28 *	George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
  29 *	et. al.
  30 *
  31 *  For licencing details see kernel-base/COPYING
  32 */
  33
  34#include <linux/cpu.h>
  35#include <linux/export.h>
  36#include <linux/percpu.h>
  37#include <linux/hrtimer.h>
  38#include <linux/notifier.h>
  39#include <linux/syscalls.h>
  40#include <linux/interrupt.h>
  41#include <linux/tick.h>
  42#include <linux/seq_file.h>
  43#include <linux/err.h>
  44#include <linux/debugobjects.h>
  45#include <linux/sched/signal.h>
  46#include <linux/sched/sysctl.h>
  47#include <linux/sched/rt.h>
  48#include <linux/sched/deadline.h>
  49#include <linux/sched/nohz.h>
  50#include <linux/sched/debug.h>
  51#include <linux/timer.h>
  52#include <linux/freezer.h>
  53#include <linux/compat.h>
  54
  55#include <linux/uaccess.h>
  56
  57#include <trace/events/timer.h>
  58
  59#include "tick-internal.h"
  60
  61/*
  62 * Masks for selecting the soft and hard context timers from
  63 * cpu_base->active
  64 */
  65#define MASK_SHIFT		(HRTIMER_BASE_MONOTONIC_SOFT)
  66#define HRTIMER_ACTIVE_HARD	((1U << MASK_SHIFT) - 1)
  67#define HRTIMER_ACTIVE_SOFT	(HRTIMER_ACTIVE_HARD << MASK_SHIFT)
  68#define HRTIMER_ACTIVE_ALL	(HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD)
  69
  70/*
  71 * The timer bases:
  72 *
  73 * There are more clockids than hrtimer bases. Thus, we index
  74 * into the timer bases by the hrtimer_base_type enum. When trying
  75 * to reach a base using a clockid, hrtimer_clockid_to_base()
  76 * is used to convert from clockid to the proper hrtimer_base_type.
  77 */
  78DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
  79{
  80	.lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
  81	.clock_base =
  82	{
  83		{
  84			.index = HRTIMER_BASE_MONOTONIC,
  85			.clockid = CLOCK_MONOTONIC,
  86			.get_time = &ktime_get,
  87		},
  88		{
  89			.index = HRTIMER_BASE_REALTIME,
  90			.clockid = CLOCK_REALTIME,
  91			.get_time = &ktime_get_real,
  92		},
  93		{
  94			.index = HRTIMER_BASE_BOOTTIME,
  95			.clockid = CLOCK_BOOTTIME,
  96			.get_time = &ktime_get_boottime,
  97		},
  98		{
  99			.index = HRTIMER_BASE_TAI,
 100			.clockid = CLOCK_TAI,
 101			.get_time = &ktime_get_clocktai,
 102		},
 103		{
 104			.index = HRTIMER_BASE_MONOTONIC_SOFT,
 105			.clockid = CLOCK_MONOTONIC,
 106			.get_time = &ktime_get,
 107		},
 108		{
 109			.index = HRTIMER_BASE_REALTIME_SOFT,
 110			.clockid = CLOCK_REALTIME,
 111			.get_time = &ktime_get_real,
 112		},
 113		{
 114			.index = HRTIMER_BASE_BOOTTIME_SOFT,
 115			.clockid = CLOCK_BOOTTIME,
 116			.get_time = &ktime_get_boottime,
 117		},
 118		{
 119			.index = HRTIMER_BASE_TAI_SOFT,
 120			.clockid = CLOCK_TAI,
 121			.get_time = &ktime_get_clocktai,
 122		},
 123	}
 124};
 125
 126static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
 127	/* Make sure we catch unsupported clockids */
 128	[0 ... MAX_CLOCKS - 1]	= HRTIMER_MAX_CLOCK_BASES,
 129
 130	[CLOCK_REALTIME]	= HRTIMER_BASE_REALTIME,
 131	[CLOCK_MONOTONIC]	= HRTIMER_BASE_MONOTONIC,
 132	[CLOCK_BOOTTIME]	= HRTIMER_BASE_BOOTTIME,
 133	[CLOCK_TAI]		= HRTIMER_BASE_TAI,
 134};
 135
 136/*
 137 * Functions and macros which are different for UP/SMP systems are kept in a
 138 * single place
 139 */
 140#ifdef CONFIG_SMP
 141
 142/*
 143 * We require the migration_base for lock_hrtimer_base()/switch_hrtimer_base()
 144 * such that hrtimer_callback_running() can unconditionally dereference
 145 * timer->base->cpu_base
 146 */
 147static struct hrtimer_cpu_base migration_cpu_base = {
 148	.clock_base = { { .cpu_base = &migration_cpu_base, }, },
 
 
 
 
 149};
 150
 151#define migration_base	migration_cpu_base.clock_base[0]
 152
 
 
 
 
 
 153/*
 154 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
 155 * means that all timers which are tied to this base via timer->base are
 156 * locked, and the base itself is locked too.
 157 *
 158 * So __run_timers/migrate_timers can safely modify all timers which could
 159 * be found on the lists/queues.
 160 *
 161 * When the timer's base is locked, and the timer removed from list, it is
 162 * possible to set timer->base = &migration_base and drop the lock: the timer
 163 * remains locked.
 164 */
 165static
 166struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
 167					     unsigned long *flags)
 168{
 169	struct hrtimer_clock_base *base;
 170
 171	for (;;) {
 172		base = 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 */
 193static int
 194hrtimer_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
 202static inline
 203struct 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 */
 225static inline struct hrtimer_clock_base *
 226switch_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);
 235again:
 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		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			timer->base = base;
 262			goto again;
 263		}
 264		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
 
 
 
 
 
 277static inline struct hrtimer_clock_base *
 278lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
 279{
 280	struct hrtimer_clock_base *base = timer->base;
 281
 282	raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
 283
 284	return base;
 285}
 286
 287# define switch_hrtimer_base(t, b, p)	(b)
 288
 289#endif	/* !CONFIG_SMP */
 290
 291/*
 292 * Functions for the union type storage format of ktime_t which are
 293 * too large for inlining:
 294 */
 295#if BITS_PER_LONG < 64
 296/*
 297 * Divide a ktime value by a nanosecond value
 298 */
 299s64 __ktime_divns(const ktime_t kt, s64 div)
 300{
 301	int sft = 0;
 302	s64 dclc;
 303	u64 tmp;
 304
 305	dclc = ktime_to_ns(kt);
 306	tmp = dclc < 0 ? -dclc : dclc;
 307
 308	/* Make sure the divisor is less than 2^32: */
 309	while (div >> 32) {
 310		sft++;
 311		div >>= 1;
 312	}
 313	tmp >>= sft;
 314	do_div(tmp, (unsigned long) div);
 315	return dclc < 0 ? -tmp : tmp;
 316}
 317EXPORT_SYMBOL_GPL(__ktime_divns);
 318#endif /* BITS_PER_LONG >= 64 */
 319
 320/*
 321 * Add two ktime values and do a safety check for overflow:
 322 */
 323ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
 324{
 325	ktime_t res = ktime_add_unsafe(lhs, rhs);
 326
 327	/*
 328	 * We use KTIME_SEC_MAX here, the maximum timeout which we can
 329	 * return to user space in a timespec:
 330	 */
 331	if (res < 0 || res < lhs || res < rhs)
 332		res = ktime_set(KTIME_SEC_MAX, 0);
 333
 334	return res;
 335}
 336
 337EXPORT_SYMBOL_GPL(ktime_add_safe);
 338
 339#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 340
 341static struct debug_obj_descr hrtimer_debug_descr;
 342
 343static void *hrtimer_debug_hint(void *addr)
 344{
 345	return ((struct hrtimer *) addr)->function;
 346}
 347
 348/*
 349 * fixup_init is called when:
 350 * - an active object is initialized
 351 */
 352static bool hrtimer_fixup_init(void *addr, enum debug_obj_state state)
 353{
 354	struct hrtimer *timer = addr;
 355
 356	switch (state) {
 357	case ODEBUG_STATE_ACTIVE:
 358		hrtimer_cancel(timer);
 359		debug_object_init(timer, &hrtimer_debug_descr);
 360		return true;
 361	default:
 362		return false;
 363	}
 364}
 365
 366/*
 367 * fixup_activate is called when:
 368 * - an active object is activated
 369 * - an unknown non-static object is activated
 370 */
 371static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
 372{
 373	switch (state) {
 374	case ODEBUG_STATE_ACTIVE:
 375		WARN_ON(1);
 376
 377	default:
 378		return false;
 379	}
 380}
 381
 382/*
 383 * fixup_free is called when:
 384 * - an active object is freed
 385 */
 386static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state)
 387{
 388	struct hrtimer *timer = addr;
 389
 390	switch (state) {
 391	case ODEBUG_STATE_ACTIVE:
 392		hrtimer_cancel(timer);
 393		debug_object_free(timer, &hrtimer_debug_descr);
 394		return true;
 395	default:
 396		return false;
 397	}
 398}
 399
 400static struct debug_obj_descr hrtimer_debug_descr = {
 401	.name		= "hrtimer",
 402	.debug_hint	= hrtimer_debug_hint,
 403	.fixup_init	= hrtimer_fixup_init,
 404	.fixup_activate	= hrtimer_fixup_activate,
 405	.fixup_free	= hrtimer_fixup_free,
 406};
 407
 408static inline void debug_hrtimer_init(struct hrtimer *timer)
 409{
 410	debug_object_init(timer, &hrtimer_debug_descr);
 411}
 412
 413static inline void debug_hrtimer_activate(struct hrtimer *timer,
 414					  enum hrtimer_mode mode)
 415{
 416	debug_object_activate(timer, &hrtimer_debug_descr);
 417}
 418
 419static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
 420{
 421	debug_object_deactivate(timer, &hrtimer_debug_descr);
 422}
 423
 424static inline void debug_hrtimer_free(struct hrtimer *timer)
 425{
 426	debug_object_free(timer, &hrtimer_debug_descr);
 427}
 428
 429static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 430			   enum hrtimer_mode mode);
 431
 432void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
 433			   enum hrtimer_mode mode)
 434{
 435	debug_object_init_on_stack(timer, &hrtimer_debug_descr);
 436	__hrtimer_init(timer, clock_id, mode);
 437}
 438EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
 439
 
 
 
 
 
 
 
 
 
 
 
 440void destroy_hrtimer_on_stack(struct hrtimer *timer)
 441{
 442	debug_object_free(timer, &hrtimer_debug_descr);
 443}
 444EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
 445
 446#else
 447
 448static inline void debug_hrtimer_init(struct hrtimer *timer) { }
 449static inline void debug_hrtimer_activate(struct hrtimer *timer,
 450					  enum hrtimer_mode mode) { }
 451static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
 452#endif
 453
 454static inline void
 455debug_init(struct hrtimer *timer, clockid_t clockid,
 456	   enum hrtimer_mode mode)
 457{
 458	debug_hrtimer_init(timer);
 459	trace_hrtimer_init(timer, clockid, mode);
 460}
 461
 462static inline void debug_activate(struct hrtimer *timer,
 463				  enum hrtimer_mode mode)
 464{
 465	debug_hrtimer_activate(timer, mode);
 466	trace_hrtimer_start(timer, mode);
 467}
 468
 469static inline void debug_deactivate(struct hrtimer *timer)
 470{
 471	debug_hrtimer_deactivate(timer);
 472	trace_hrtimer_cancel(timer);
 473}
 474
 475static struct hrtimer_clock_base *
 476__next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
 477{
 478	unsigned int idx;
 479
 480	if (!*active)
 481		return NULL;
 482
 483	idx = __ffs(*active);
 484	*active &= ~(1U << idx);
 485
 486	return &cpu_base->clock_base[idx];
 487}
 488
 489#define for_each_active_base(base, cpu_base, active)	\
 490	while ((base = __next_base((cpu_base), &(active))))
 491
 492static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
 493					 const struct hrtimer *exclude,
 494					 unsigned int active,
 495					 ktime_t expires_next)
 496{
 497	struct hrtimer_clock_base *base;
 498	ktime_t expires;
 499
 500	for_each_active_base(base, cpu_base, active) {
 501		struct timerqueue_node *next;
 502		struct hrtimer *timer;
 503
 504		next = timerqueue_getnext(&base->active);
 505		timer = container_of(next, struct hrtimer, node);
 506		if (timer == exclude) {
 507			/* Get to the next timer in the queue. */
 508			next = timerqueue_iterate_next(next);
 509			if (!next)
 510				continue;
 511
 512			timer = container_of(next, struct hrtimer, node);
 513		}
 514		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
 515		if (expires < expires_next) {
 516			expires_next = expires;
 517
 518			/* Skip cpu_base update if a timer is being excluded. */
 519			if (exclude)
 520				continue;
 521
 522			if (timer->is_soft)
 523				cpu_base->softirq_next_timer = timer;
 524			else
 525				cpu_base->next_timer = timer;
 526		}
 527	}
 528	/*
 529	 * clock_was_set() might have changed base->offset of any of
 530	 * the clock bases so the result might be negative. Fix it up
 531	 * to prevent a false positive in clockevents_program_event().
 532	 */
 533	if (expires_next < 0)
 534		expires_next = 0;
 535	return expires_next;
 536}
 537
 538/*
 539 * Recomputes cpu_base::*next_timer and returns the earliest expires_next but
 540 * does not set cpu_base::*expires_next, that is done by hrtimer_reprogram.
 541 *
 542 * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
 543 * those timers will get run whenever the softirq gets handled, at the end of
 544 * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
 545 *
 546 * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
 547 * The !softirq values are the minima across HRTIMER_ACTIVE_ALL, unless an actual
 548 * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
 549 *
 550 * @active_mask must be one of:
 551 *  - HRTIMER_ACTIVE_ALL,
 552 *  - HRTIMER_ACTIVE_SOFT, or
 553 *  - HRTIMER_ACTIVE_HARD.
 554 */
 555static ktime_t
 556__hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
 557{
 558	unsigned int active;
 559	struct hrtimer *next_timer = NULL;
 560	ktime_t expires_next = KTIME_MAX;
 561
 562	if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
 563		active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
 564		cpu_base->softirq_next_timer = NULL;
 565		expires_next = __hrtimer_next_event_base(cpu_base, NULL,
 566							 active, KTIME_MAX);
 567
 568		next_timer = cpu_base->softirq_next_timer;
 569	}
 570
 571	if (active_mask & HRTIMER_ACTIVE_HARD) {
 572		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
 573		cpu_base->next_timer = next_timer;
 574		expires_next = __hrtimer_next_event_base(cpu_base, NULL, active,
 575							 expires_next);
 576	}
 577
 578	return expires_next;
 579}
 580
 581static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
 582{
 583	ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
 584	ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
 585	ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
 586
 587	ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
 588					    offs_real, offs_boot, offs_tai);
 589
 590	base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
 591	base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
 592	base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
 593
 594	return now;
 595}
 596
 597/*
 598 * Is the high resolution mode active ?
 599 */
 600static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
 601{
 602	return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
 603		cpu_base->hres_active : 0;
 604}
 605
 606static inline int hrtimer_hres_active(void)
 607{
 608	return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
 609}
 610
 611/*
 612 * Reprogram the event source with checking both queues for the
 613 * next event
 614 * Called with interrupts disabled and base->lock held
 615 */
 616static void
 617hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
 618{
 619	ktime_t expires_next;
 620
 621	/*
 622	 * Find the current next expiration time.
 623	 */
 624	expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
 625
 626	if (cpu_base->next_timer && cpu_base->next_timer->is_soft) {
 627		/*
 628		 * When the softirq is activated, hrtimer has to be
 629		 * programmed with the first hard hrtimer because soft
 630		 * timer interrupt could occur too late.
 631		 */
 632		if (cpu_base->softirq_activated)
 633			expires_next = __hrtimer_get_next_event(cpu_base,
 634								HRTIMER_ACTIVE_HARD);
 635		else
 636			cpu_base->softirq_expires_next = expires_next;
 637	}
 638
 639	if (skip_equal && expires_next == cpu_base->expires_next)
 640		return;
 641
 642	cpu_base->expires_next = expires_next;
 643
 644	/*
 645	 * If hres is not active, hardware does not have to be
 646	 * reprogrammed yet.
 647	 *
 648	 * If a hang was detected in the last timer interrupt then we
 649	 * leave the hang delay active in the hardware. We want the
 650	 * system to make progress. That also prevents the following
 651	 * scenario:
 652	 * T1 expires 50ms from now
 653	 * T2 expires 5s from now
 654	 *
 655	 * T1 is removed, so this code is called and would reprogram
 656	 * the hardware to 5s from now. Any hrtimer_start after that
 657	 * will not reprogram the hardware due to hang_detected being
 658	 * set. So we'd effectivly block all timers until the T2 event
 659	 * fires.
 660	 */
 661	if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
 662		return;
 663
 664	tick_program_event(cpu_base->expires_next, 1);
 665}
 666
 667/* High resolution timer related functions */
 668#ifdef CONFIG_HIGH_RES_TIMERS
 669
 670/*
 671 * High resolution timer enabled ?
 672 */
 673static bool hrtimer_hres_enabled __read_mostly  = true;
 674unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
 675EXPORT_SYMBOL_GPL(hrtimer_resolution);
 676
 677/*
 678 * Enable / Disable high resolution mode
 679 */
 680static int __init setup_hrtimer_hres(char *str)
 681{
 682	return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
 683}
 684
 685__setup("highres=", setup_hrtimer_hres);
 686
 687/*
 688 * hrtimer_high_res_enabled - query, if the highres mode is enabled
 689 */
 690static inline int hrtimer_is_hres_enabled(void)
 691{
 692	return hrtimer_hres_enabled;
 693}
 694
 695/*
 696 * Retrigger next event is called after clock was set
 697 *
 698 * Called with interrupts disabled via on_each_cpu()
 699 */
 700static void retrigger_next_event(void *arg)
 701{
 702	struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
 703
 704	if (!__hrtimer_hres_active(base))
 705		return;
 706
 707	raw_spin_lock(&base->lock);
 708	hrtimer_update_base(base);
 709	hrtimer_force_reprogram(base, 0);
 710	raw_spin_unlock(&base->lock);
 711}
 712
 713/*
 714 * Switch to high resolution mode
 715 */
 716static void hrtimer_switch_to_hres(void)
 717{
 718	struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
 719
 720	if (tick_init_highres()) {
 721		printk(KERN_WARNING "Could not switch to high resolution "
 722				    "mode on CPU %d\n", base->cpu);
 723		return;
 724	}
 725	base->hres_active = 1;
 726	hrtimer_resolution = HIGH_RES_NSEC;
 727
 728	tick_setup_sched_timer();
 729	/* "Retrigger" the interrupt to get things going */
 730	retrigger_next_event(NULL);
 731}
 732
 733static void clock_was_set_work(struct work_struct *work)
 734{
 735	clock_was_set();
 736}
 737
 738static DECLARE_WORK(hrtimer_work, clock_was_set_work);
 739
 740/*
 741 * Called from timekeeping and resume code to reprogram the hrtimer
 742 * interrupt device on all cpus.
 743 */
 744void clock_was_set_delayed(void)
 745{
 746	schedule_work(&hrtimer_work);
 747}
 748
 749#else
 750
 751static inline int hrtimer_is_hres_enabled(void) { return 0; }
 752static inline void hrtimer_switch_to_hres(void) { }
 753static inline void retrigger_next_event(void *arg) { }
 754
 755#endif /* CONFIG_HIGH_RES_TIMERS */
 756
 757/*
 758 * When a timer is enqueued and expires earlier than the already enqueued
 759 * timers, we have to check, whether it expires earlier than the timer for
 760 * which the clock event device was armed.
 761 *
 762 * Called with interrupts disabled and base->cpu_base.lock held
 763 */
 764static void hrtimer_reprogram(struct hrtimer *timer, bool reprogram)
 765{
 766	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
 767	struct hrtimer_clock_base *base = timer->base;
 768	ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
 769
 770	WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
 771
 772	/*
 773	 * CLOCK_REALTIME timer might be requested with an absolute
 774	 * expiry time which is less than base->offset. Set it to 0.
 775	 */
 776	if (expires < 0)
 777		expires = 0;
 778
 779	if (timer->is_soft) {
 780		/*
 781		 * soft hrtimer could be started on a remote CPU. In this
 782		 * case softirq_expires_next needs to be updated on the
 783		 * remote CPU. The soft hrtimer will not expire before the
 784		 * first hard hrtimer on the remote CPU -
 785		 * hrtimer_check_target() prevents this case.
 786		 */
 787		struct hrtimer_cpu_base *timer_cpu_base = base->cpu_base;
 788
 789		if (timer_cpu_base->softirq_activated)
 790			return;
 791
 792		if (!ktime_before(expires, timer_cpu_base->softirq_expires_next))
 793			return;
 794
 795		timer_cpu_base->softirq_next_timer = timer;
 796		timer_cpu_base->softirq_expires_next = expires;
 797
 798		if (!ktime_before(expires, timer_cpu_base->expires_next) ||
 799		    !reprogram)
 800			return;
 801	}
 802
 803	/*
 804	 * If the timer is not on the current cpu, we cannot reprogram
 805	 * the other cpus clock event device.
 806	 */
 807	if (base->cpu_base != cpu_base)
 808		return;
 809
 810	/*
 811	 * If the hrtimer interrupt is running, then it will
 812	 * reevaluate the clock bases and reprogram the clock event
 813	 * device. The callbacks are always executed in hard interrupt
 814	 * context so we don't need an extra check for a running
 815	 * callback.
 816	 */
 817	if (cpu_base->in_hrtirq)
 818		return;
 819
 820	if (expires >= cpu_base->expires_next)
 821		return;
 822
 823	/* Update the pointer to the next expiring timer */
 824	cpu_base->next_timer = timer;
 825	cpu_base->expires_next = expires;
 826
 827	/*
 828	 * If hres is not active, hardware does not have to be
 829	 * programmed yet.
 830	 *
 831	 * If a hang was detected in the last timer interrupt then we
 832	 * do not schedule a timer which is earlier than the expiry
 833	 * which we enforced in the hang detection. We want the system
 834	 * to make progress.
 835	 */
 836	if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
 837		return;
 838
 839	/*
 840	 * Program the timer hardware. We enforce the expiry for
 841	 * events which are already in the past.
 842	 */
 843	tick_program_event(expires, 1);
 844}
 845
 846/*
 847 * Clock realtime was set
 848 *
 849 * Change the offset of the realtime clock vs. the monotonic
 850 * clock.
 851 *
 852 * We might have to reprogram the high resolution timer interrupt. On
 853 * SMP we call the architecture specific code to retrigger _all_ high
 854 * resolution timer interrupts. On UP we just disable interrupts and
 855 * call the high resolution interrupt code.
 856 */
 857void clock_was_set(void)
 858{
 859#ifdef CONFIG_HIGH_RES_TIMERS
 860	/* Retrigger the CPU local events everywhere */
 861	on_each_cpu(retrigger_next_event, NULL, 1);
 862#endif
 863	timerfd_clock_was_set();
 864}
 865
 866/*
 867 * During resume we might have to reprogram the high resolution timer
 868 * interrupt on all online CPUs.  However, all other CPUs will be
 869 * stopped with IRQs interrupts disabled so the clock_was_set() call
 870 * must be deferred.
 871 */
 872void hrtimers_resume(void)
 873{
 874	lockdep_assert_irqs_disabled();
 875	/* Retrigger on the local CPU */
 876	retrigger_next_event(NULL);
 877	/* And schedule a retrigger for all others */
 878	clock_was_set_delayed();
 879}
 880
 881/*
 882 * Counterpart to lock_hrtimer_base above:
 883 */
 884static inline
 885void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
 886{
 887	raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
 888}
 889
 890/**
 891 * hrtimer_forward - forward the timer expiry
 892 * @timer:	hrtimer to forward
 893 * @now:	forward past this time
 894 * @interval:	the interval to forward
 895 *
 896 * Forward the timer expiry so it will expire in the future.
 897 * Returns the number of overruns.
 898 *
 899 * Can be safely called from the callback function of @timer. If
 900 * called from other contexts @timer must neither be enqueued nor
 901 * running the callback and the caller needs to take care of
 902 * serialization.
 903 *
 904 * Note: This only updates the timer expiry value and does not requeue
 905 * the timer.
 906 */
 907u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
 908{
 909	u64 orun = 1;
 910	ktime_t delta;
 911
 912	delta = ktime_sub(now, hrtimer_get_expires(timer));
 913
 914	if (delta < 0)
 915		return 0;
 916
 917	if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
 918		return 0;
 919
 920	if (interval < hrtimer_resolution)
 921		interval = hrtimer_resolution;
 922
 923	if (unlikely(delta >= interval)) {
 924		s64 incr = ktime_to_ns(interval);
 925
 926		orun = ktime_divns(delta, incr);
 927		hrtimer_add_expires_ns(timer, incr * orun);
 928		if (hrtimer_get_expires_tv64(timer) > now)
 929			return orun;
 930		/*
 931		 * This (and the ktime_add() below) is the
 932		 * correction for exact:
 933		 */
 934		orun++;
 935	}
 936	hrtimer_add_expires(timer, interval);
 937
 938	return orun;
 939}
 940EXPORT_SYMBOL_GPL(hrtimer_forward);
 941
 942/*
 943 * enqueue_hrtimer - internal function to (re)start a timer
 944 *
 945 * The timer is inserted in expiry order. Insertion into the
 946 * red black tree is O(log(n)). Must hold the base lock.
 947 *
 948 * Returns 1 when the new timer is the leftmost timer in the tree.
 949 */
 950static int enqueue_hrtimer(struct hrtimer *timer,
 951			   struct hrtimer_clock_base *base,
 952			   enum hrtimer_mode mode)
 953{
 954	debug_activate(timer, mode);
 955
 956	base->cpu_base->active_bases |= 1 << base->index;
 957
 958	timer->state = HRTIMER_STATE_ENQUEUED;
 
 959
 960	return timerqueue_add(&base->active, &timer->node);
 961}
 962
 963/*
 964 * __remove_hrtimer - internal function to remove a timer
 965 *
 966 * Caller must hold the base lock.
 967 *
 968 * High resolution timer mode reprograms the clock event device when the
 969 * timer is the one which expires next. The caller can disable this by setting
 970 * reprogram to zero. This is useful, when the context does a reprogramming
 971 * anyway (e.g. timer interrupt)
 972 */
 973static void __remove_hrtimer(struct hrtimer *timer,
 974			     struct hrtimer_clock_base *base,
 975			     u8 newstate, int reprogram)
 976{
 977	struct hrtimer_cpu_base *cpu_base = base->cpu_base;
 978	u8 state = timer->state;
 979
 980	timer->state = newstate;
 
 981	if (!(state & HRTIMER_STATE_ENQUEUED))
 982		return;
 983
 984	if (!timerqueue_del(&base->active, &timer->node))
 985		cpu_base->active_bases &= ~(1 << base->index);
 986
 987	/*
 988	 * Note: If reprogram is false we do not update
 989	 * cpu_base->next_timer. This happens when we remove the first
 990	 * timer on a remote cpu. No harm as we never dereference
 991	 * cpu_base->next_timer. So the worst thing what can happen is
 992	 * an superflous call to hrtimer_force_reprogram() on the
 993	 * remote cpu later on if the same timer gets enqueued again.
 994	 */
 995	if (reprogram && timer == cpu_base->next_timer)
 996		hrtimer_force_reprogram(cpu_base, 1);
 997}
 998
 999/*
1000 * remove hrtimer, called with base lock held
1001 */
1002static inline int
1003remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base, bool restart)
1004{
1005	if (hrtimer_is_queued(timer)) {
1006		u8 state = timer->state;
 
1007		int reprogram;
1008
1009		/*
1010		 * Remove the timer and force reprogramming when high
1011		 * resolution mode is active and the timer is on the current
1012		 * CPU. If we remove a timer on another CPU, reprogramming is
1013		 * skipped. The interrupt event on this CPU is fired and
1014		 * reprogramming happens in the interrupt handler. This is a
1015		 * rare case and less expensive than a smp call.
1016		 */
1017		debug_deactivate(timer);
1018		reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1019
1020		if (!restart)
1021			state = HRTIMER_STATE_INACTIVE;
1022
1023		__remove_hrtimer(timer, base, state, reprogram);
1024		return 1;
1025	}
1026	return 0;
1027}
1028
1029static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
1030					    const enum hrtimer_mode mode)
1031{
1032#ifdef CONFIG_TIME_LOW_RES
1033	/*
1034	 * CONFIG_TIME_LOW_RES indicates that the system has no way to return
1035	 * granular time values. For relative timers we add hrtimer_resolution
1036	 * (i.e. one jiffie) to prevent short timeouts.
1037	 */
1038	timer->is_rel = mode & HRTIMER_MODE_REL;
1039	if (timer->is_rel)
1040		tim = ktime_add_safe(tim, hrtimer_resolution);
1041#endif
1042	return tim;
1043}
1044
1045static void
1046hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
1047{
1048	ktime_t expires;
1049
1050	/*
1051	 * Find the next SOFT expiration.
1052	 */
1053	expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
1054
1055	/*
1056	 * reprogramming needs to be triggered, even if the next soft
1057	 * hrtimer expires at the same time than the next hard
1058	 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
1059	 */
1060	if (expires == KTIME_MAX)
1061		return;
1062
1063	/*
1064	 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
1065	 * cpu_base->*expires_next is only set by hrtimer_reprogram()
1066	 */
1067	hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
1068}
1069
1070static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1071				    u64 delta_ns, const enum hrtimer_mode mode,
1072				    struct hrtimer_clock_base *base)
1073{
1074	struct hrtimer_clock_base *new_base;
1075
1076	/* Remove an active timer from the queue: */
1077	remove_hrtimer(timer, base, true);
1078
1079	if (mode & HRTIMER_MODE_REL)
1080		tim = ktime_add_safe(tim, base->get_time());
1081
1082	tim = hrtimer_update_lowres(timer, tim, mode);
1083
1084	hrtimer_set_expires_range_ns(timer, tim, delta_ns);
1085
1086	/* Switch the timer base, if necessary: */
1087	new_base = switch_hrtimer_base(timer, base, mode & HRTIMER_MODE_PINNED);
1088
1089	return enqueue_hrtimer(timer, new_base, mode);
1090}
1091
1092/**
1093 * hrtimer_start_range_ns - (re)start an hrtimer
1094 * @timer:	the timer to be added
1095 * @tim:	expiry time
1096 * @delta_ns:	"slack" range for the timer
1097 * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
1098 *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
1099 *		softirq based mode is considered for debug purpose only!
1100 */
1101void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1102			    u64 delta_ns, const enum hrtimer_mode mode)
1103{
1104	struct hrtimer_clock_base *base;
1105	unsigned long flags;
1106
1107	/*
1108	 * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
1109	 * match.
 
1110	 */
1111	WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
 
 
 
1112
1113	base = lock_hrtimer_base(timer, &flags);
1114
1115	if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
1116		hrtimer_reprogram(timer, true);
1117
1118	unlock_hrtimer_base(timer, &flags);
1119}
1120EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1121
1122/**
1123 * hrtimer_try_to_cancel - try to deactivate a timer
1124 * @timer:	hrtimer to stop
1125 *
1126 * Returns:
1127 *  0 when the timer was not active
1128 *  1 when the timer was active
1129 * -1 when the timer is currently executing the callback function and
 
1130 *    cannot be stopped
1131 */
1132int hrtimer_try_to_cancel(struct hrtimer *timer)
1133{
1134	struct hrtimer_clock_base *base;
1135	unsigned long flags;
1136	int ret = -1;
1137
1138	/*
1139	 * Check lockless first. If the timer is not active (neither
1140	 * enqueued nor running the callback, nothing to do here.  The
1141	 * base lock does not serialize against a concurrent enqueue,
1142	 * so we can avoid taking it.
1143	 */
1144	if (!hrtimer_active(timer))
1145		return 0;
1146
1147	base = lock_hrtimer_base(timer, &flags);
1148
1149	if (!hrtimer_callback_running(timer))
1150		ret = remove_hrtimer(timer, base, false);
1151
1152	unlock_hrtimer_base(timer, &flags);
1153
1154	return ret;
1155
1156}
1157EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1158
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1159/**
1160 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1161 * @timer:	the timer to be cancelled
1162 *
1163 * Returns:
1164 *  0 when the timer was not active
1165 *  1 when the timer was active
1166 */
1167int hrtimer_cancel(struct hrtimer *timer)
1168{
1169	for (;;) {
1170		int ret = hrtimer_try_to_cancel(timer);
1171
1172		if (ret >= 0)
1173			return ret;
1174		cpu_relax();
1175	}
 
 
 
1176}
1177EXPORT_SYMBOL_GPL(hrtimer_cancel);
1178
1179/**
1180 * hrtimer_get_remaining - get remaining time for the timer
1181 * @timer:	the timer to read
1182 * @adjust:	adjust relative timers when CONFIG_TIME_LOW_RES=y
1183 */
1184ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
1185{
1186	unsigned long flags;
1187	ktime_t rem;
1188
1189	lock_hrtimer_base(timer, &flags);
1190	if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
1191		rem = hrtimer_expires_remaining_adjusted(timer);
1192	else
1193		rem = hrtimer_expires_remaining(timer);
1194	unlock_hrtimer_base(timer, &flags);
1195
1196	return rem;
1197}
1198EXPORT_SYMBOL_GPL(__hrtimer_get_remaining);
1199
1200#ifdef CONFIG_NO_HZ_COMMON
1201/**
1202 * hrtimer_get_next_event - get the time until next expiry event
1203 *
1204 * Returns the next expiry time or KTIME_MAX if no timer is pending.
1205 */
1206u64 hrtimer_get_next_event(void)
1207{
1208	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1209	u64 expires = KTIME_MAX;
1210	unsigned long flags;
1211
1212	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1213
1214	if (!__hrtimer_hres_active(cpu_base))
1215		expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
1216
1217	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1218
1219	return expires;
1220}
1221
1222/**
1223 * hrtimer_next_event_without - time until next expiry event w/o one timer
1224 * @exclude:	timer to exclude
1225 *
1226 * Returns the next expiry time over all timers except for the @exclude one or
1227 * KTIME_MAX if none of them is pending.
1228 */
1229u64 hrtimer_next_event_without(const struct hrtimer *exclude)
1230{
1231	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1232	u64 expires = KTIME_MAX;
1233	unsigned long flags;
1234
1235	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1236
1237	if (__hrtimer_hres_active(cpu_base)) {
1238		unsigned int active;
1239
1240		if (!cpu_base->softirq_activated) {
1241			active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
1242			expires = __hrtimer_next_event_base(cpu_base, exclude,
1243							    active, KTIME_MAX);
1244		}
1245		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
1246		expires = __hrtimer_next_event_base(cpu_base, exclude, active,
1247						    expires);
1248	}
1249
1250	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1251
1252	return expires;
1253}
1254#endif
1255
1256static inline int hrtimer_clockid_to_base(clockid_t clock_id)
1257{
1258	if (likely(clock_id < MAX_CLOCKS)) {
1259		int base = hrtimer_clock_to_base_table[clock_id];
1260
1261		if (likely(base != HRTIMER_MAX_CLOCK_BASES))
1262			return base;
1263	}
1264	WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
1265	return HRTIMER_BASE_MONOTONIC;
1266}
1267
1268static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1269			   enum hrtimer_mode mode)
1270{
1271	bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
1272	int base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
1273	struct hrtimer_cpu_base *cpu_base;
 
 
 
 
 
 
 
 
 
 
1274
1275	memset(timer, 0, sizeof(struct hrtimer));
1276
1277	cpu_base = raw_cpu_ptr(&hrtimer_bases);
1278
1279	/*
1280	 * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
1281	 * clock modifications, so they needs to become CLOCK_MONOTONIC to
1282	 * ensure POSIX compliance.
1283	 */
1284	if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
1285		clock_id = CLOCK_MONOTONIC;
1286
 
1287	base += hrtimer_clockid_to_base(clock_id);
1288	timer->is_soft = softtimer;
 
1289	timer->base = &cpu_base->clock_base[base];
1290	timerqueue_init(&timer->node);
1291}
1292
1293/**
1294 * hrtimer_init - initialize a timer to the given clock
1295 * @timer:	the timer to be initialized
1296 * @clock_id:	the clock to be used
1297 * @mode:       The modes which are relevant for intitialization:
1298 *              HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
1299 *              HRTIMER_MODE_REL_SOFT
1300 *
1301 *              The PINNED variants of the above can be handed in,
1302 *              but the PINNED bit is ignored as pinning happens
1303 *              when the hrtimer is started
1304 */
1305void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1306		  enum hrtimer_mode mode)
1307{
1308	debug_init(timer, clock_id, mode);
1309	__hrtimer_init(timer, clock_id, mode);
1310}
1311EXPORT_SYMBOL_GPL(hrtimer_init);
1312
1313/*
1314 * A timer is active, when it is enqueued into the rbtree or the
1315 * callback function is running or it's in the state of being migrated
1316 * to another cpu.
1317 *
1318 * It is important for this function to not return a false negative.
1319 */
1320bool hrtimer_active(const struct hrtimer *timer)
1321{
1322	struct hrtimer_clock_base *base;
1323	unsigned int seq;
1324
1325	do {
1326		base = READ_ONCE(timer->base);
1327		seq = raw_read_seqcount_begin(&base->seq);
1328
1329		if (timer->state != HRTIMER_STATE_INACTIVE ||
1330		    base->running == timer)
1331			return true;
1332
1333	} while (read_seqcount_retry(&base->seq, seq) ||
1334		 base != READ_ONCE(timer->base));
1335
1336	return false;
1337}
1338EXPORT_SYMBOL_GPL(hrtimer_active);
1339
1340/*
1341 * The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
1342 * distinct sections:
1343 *
1344 *  - queued:	the timer is queued
1345 *  - callback:	the timer is being ran
1346 *  - post:	the timer is inactive or (re)queued
1347 *
1348 * On the read side we ensure we observe timer->state and cpu_base->running
1349 * from the same section, if anything changed while we looked at it, we retry.
1350 * This includes timer->base changing because sequence numbers alone are
1351 * insufficient for that.
1352 *
1353 * The sequence numbers are required because otherwise we could still observe
1354 * a false negative if the read side got smeared over multiple consequtive
1355 * __run_hrtimer() invocations.
1356 */
1357
1358static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
1359			  struct hrtimer_clock_base *base,
1360			  struct hrtimer *timer, ktime_t *now,
1361			  unsigned long flags)
1362{
1363	enum hrtimer_restart (*fn)(struct hrtimer *);
 
1364	int restart;
1365
1366	lockdep_assert_held(&cpu_base->lock);
1367
1368	debug_deactivate(timer);
1369	base->running = timer;
1370
1371	/*
1372	 * Separate the ->running assignment from the ->state assignment.
1373	 *
1374	 * As with a regular write barrier, this ensures the read side in
1375	 * hrtimer_active() cannot observe base->running == NULL &&
1376	 * timer->state == INACTIVE.
1377	 */
1378	raw_write_seqcount_barrier(&base->seq);
1379
1380	__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
1381	fn = timer->function;
1382
1383	/*
1384	 * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
1385	 * timer is restarted with a period then it becomes an absolute
1386	 * timer. If its not restarted it does not matter.
1387	 */
1388	if (IS_ENABLED(CONFIG_TIME_LOW_RES))
1389		timer->is_rel = false;
1390
1391	/*
1392	 * The timer is marked as running in the CPU base, so it is
1393	 * protected against migration to a different CPU even if the lock
1394	 * is dropped.
1395	 */
1396	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1397	trace_hrtimer_expire_entry(timer, now);
 
 
1398	restart = fn(timer);
 
 
1399	trace_hrtimer_expire_exit(timer);
1400	raw_spin_lock_irq(&cpu_base->lock);
1401
1402	/*
1403	 * Note: We clear the running state after enqueue_hrtimer and
1404	 * we do not reprogram the event hardware. Happens either in
1405	 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1406	 *
1407	 * Note: Because we dropped the cpu_base->lock above,
1408	 * hrtimer_start_range_ns() can have popped in and enqueued the timer
1409	 * for us already.
1410	 */
1411	if (restart != HRTIMER_NORESTART &&
1412	    !(timer->state & HRTIMER_STATE_ENQUEUED))
1413		enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
1414
1415	/*
1416	 * Separate the ->running assignment from the ->state assignment.
1417	 *
1418	 * As with a regular write barrier, this ensures the read side in
1419	 * hrtimer_active() cannot observe base->running.timer == NULL &&
1420	 * timer->state == INACTIVE.
1421	 */
1422	raw_write_seqcount_barrier(&base->seq);
1423
1424	WARN_ON_ONCE(base->running != timer);
1425	base->running = NULL;
1426}
1427
1428static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
1429				 unsigned long flags, unsigned int active_mask)
1430{
1431	struct hrtimer_clock_base *base;
1432	unsigned int active = cpu_base->active_bases & active_mask;
1433
1434	for_each_active_base(base, cpu_base, active) {
1435		struct timerqueue_node *node;
1436		ktime_t basenow;
1437
1438		basenow = ktime_add(now, base->offset);
1439
1440		while ((node = timerqueue_getnext(&base->active))) {
1441			struct hrtimer *timer;
1442
1443			timer = container_of(node, struct hrtimer, node);
1444
1445			/*
1446			 * The immediate goal for using the softexpires is
1447			 * minimizing wakeups, not running timers at the
1448			 * earliest interrupt after their soft expiration.
1449			 * This allows us to avoid using a Priority Search
1450			 * Tree, which can answer a stabbing querry for
1451			 * overlapping intervals and instead use the simple
1452			 * BST we already have.
1453			 * We don't add extra wakeups by delaying timers that
1454			 * are right-of a not yet expired timer, because that
1455			 * timer will have to trigger a wakeup anyway.
1456			 */
1457			if (basenow < hrtimer_get_softexpires_tv64(timer))
1458				break;
1459
1460			__run_hrtimer(cpu_base, base, timer, &basenow, flags);
 
 
1461		}
1462	}
1463}
1464
1465static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
1466{
1467	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1468	unsigned long flags;
1469	ktime_t now;
1470
 
1471	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1472
1473	now = hrtimer_update_base(cpu_base);
1474	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
1475
1476	cpu_base->softirq_activated = 0;
1477	hrtimer_update_softirq_timer(cpu_base, true);
1478
1479	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 
1480}
1481
1482#ifdef CONFIG_HIGH_RES_TIMERS
1483
1484/*
1485 * High resolution timer interrupt
1486 * Called with interrupts disabled
1487 */
1488void hrtimer_interrupt(struct clock_event_device *dev)
1489{
1490	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1491	ktime_t expires_next, now, entry_time, delta;
1492	unsigned long flags;
1493	int retries = 0;
1494
1495	BUG_ON(!cpu_base->hres_active);
1496	cpu_base->nr_events++;
1497	dev->next_event = KTIME_MAX;
1498
1499	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1500	entry_time = now = hrtimer_update_base(cpu_base);
1501retry:
1502	cpu_base->in_hrtirq = 1;
1503	/*
1504	 * We set expires_next to KTIME_MAX here with cpu_base->lock
1505	 * held to prevent that a timer is enqueued in our queue via
1506	 * the migration code. This does not affect enqueueing of
1507	 * timers which run their callback and need to be requeued on
1508	 * this CPU.
1509	 */
1510	cpu_base->expires_next = KTIME_MAX;
1511
1512	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1513		cpu_base->softirq_expires_next = KTIME_MAX;
1514		cpu_base->softirq_activated = 1;
1515		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1516	}
1517
1518	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1519
1520	/* Reevaluate the clock bases for the next expiry */
1521	expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
1522	/*
1523	 * Store the new expiry value so the migration code can verify
1524	 * against it.
1525	 */
1526	cpu_base->expires_next = expires_next;
1527	cpu_base->in_hrtirq = 0;
1528	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1529
1530	/* Reprogramming necessary ? */
1531	if (!tick_program_event(expires_next, 0)) {
1532		cpu_base->hang_detected = 0;
1533		return;
1534	}
1535
1536	/*
1537	 * The next timer was already expired due to:
1538	 * - tracing
1539	 * - long lasting callbacks
1540	 * - being scheduled away when running in a VM
1541	 *
1542	 * We need to prevent that we loop forever in the hrtimer
1543	 * interrupt routine. We give it 3 attempts to avoid
1544	 * overreacting on some spurious event.
1545	 *
1546	 * Acquire base lock for updating the offsets and retrieving
1547	 * the current time.
1548	 */
1549	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1550	now = hrtimer_update_base(cpu_base);
1551	cpu_base->nr_retries++;
1552	if (++retries < 3)
1553		goto retry;
1554	/*
1555	 * Give the system a chance to do something else than looping
1556	 * here. We stored the entry time, so we know exactly how long
1557	 * we spent here. We schedule the next event this amount of
1558	 * time away.
1559	 */
1560	cpu_base->nr_hangs++;
1561	cpu_base->hang_detected = 1;
1562	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1563
1564	delta = ktime_sub(now, entry_time);
1565	if ((unsigned int)delta > cpu_base->max_hang_time)
1566		cpu_base->max_hang_time = (unsigned int) delta;
1567	/*
1568	 * Limit it to a sensible value as we enforce a longer
1569	 * delay. Give the CPU at least 100ms to catch up.
1570	 */
1571	if (delta > 100 * NSEC_PER_MSEC)
1572		expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1573	else
1574		expires_next = ktime_add(now, delta);
1575	tick_program_event(expires_next, 1);
1576	printk_once(KERN_WARNING "hrtimer: interrupt took %llu ns\n",
1577		    ktime_to_ns(delta));
1578}
1579
1580/* called with interrupts disabled */
1581static inline void __hrtimer_peek_ahead_timers(void)
1582{
1583	struct tick_device *td;
1584
1585	if (!hrtimer_hres_active())
1586		return;
1587
1588	td = this_cpu_ptr(&tick_cpu_device);
1589	if (td && td->evtdev)
1590		hrtimer_interrupt(td->evtdev);
1591}
1592
1593#else /* CONFIG_HIGH_RES_TIMERS */
1594
1595static inline void __hrtimer_peek_ahead_timers(void) { }
1596
1597#endif	/* !CONFIG_HIGH_RES_TIMERS */
1598
1599/*
1600 * Called from run_local_timers in hardirq context every jiffy
1601 */
1602void hrtimer_run_queues(void)
1603{
1604	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1605	unsigned long flags;
1606	ktime_t now;
1607
1608	if (__hrtimer_hres_active(cpu_base))
1609		return;
1610
1611	/*
1612	 * This _is_ ugly: We have to check periodically, whether we
1613	 * can switch to highres and / or nohz mode. The clocksource
1614	 * switch happens with xtime_lock held. Notification from
1615	 * there only sets the check bit in the tick_oneshot code,
1616	 * otherwise we might deadlock vs. xtime_lock.
1617	 */
1618	if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
1619		hrtimer_switch_to_hres();
1620		return;
1621	}
1622
1623	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1624	now = hrtimer_update_base(cpu_base);
1625
1626	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1627		cpu_base->softirq_expires_next = KTIME_MAX;
1628		cpu_base->softirq_activated = 1;
1629		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1630	}
1631
1632	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1633	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1634}
1635
1636/*
1637 * Sleep related functions:
1638 */
1639static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1640{
1641	struct hrtimer_sleeper *t =
1642		container_of(timer, struct hrtimer_sleeper, timer);
1643	struct task_struct *task = t->task;
1644
1645	t->task = NULL;
1646	if (task)
1647		wake_up_process(task);
1648
1649	return HRTIMER_NORESTART;
1650}
1651
1652void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, struct task_struct *task)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1653{
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1654	sl->timer.function = hrtimer_wakeup;
1655	sl->task = task;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1656}
1657EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
1658
1659int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
1660{
1661	switch(restart->nanosleep.type) {
1662#ifdef CONFIG_COMPAT
1663	case TT_COMPAT:
1664		if (compat_put_timespec64(ts, restart->nanosleep.compat_rmtp))
1665			return -EFAULT;
1666		break;
1667#endif
1668	case TT_NATIVE:
1669		if (put_timespec64(ts, restart->nanosleep.rmtp))
1670			return -EFAULT;
1671		break;
1672	default:
1673		BUG();
1674	}
1675	return -ERESTART_RESTARTBLOCK;
1676}
1677
1678static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
1679{
1680	struct restart_block *restart;
1681
1682	hrtimer_init_sleeper(t, current);
1683
1684	do {
1685		set_current_state(TASK_INTERRUPTIBLE);
1686		hrtimer_start_expires(&t->timer, mode);
1687
1688		if (likely(t->task))
1689			freezable_schedule();
1690
1691		hrtimer_cancel(&t->timer);
1692		mode = HRTIMER_MODE_ABS;
1693
1694	} while (t->task && !signal_pending(current));
1695
1696	__set_current_state(TASK_RUNNING);
1697
1698	if (!t->task)
1699		return 0;
1700
1701	restart = &current->restart_block;
1702	if (restart->nanosleep.type != TT_NONE) {
1703		ktime_t rem = hrtimer_expires_remaining(&t->timer);
1704		struct timespec64 rmt;
1705
1706		if (rem <= 0)
1707			return 0;
1708		rmt = ktime_to_timespec64(rem);
1709
1710		return nanosleep_copyout(restart, &rmt);
1711	}
1712	return -ERESTART_RESTARTBLOCK;
1713}
1714
1715static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
1716{
1717	struct hrtimer_sleeper t;
1718	int ret;
1719
1720	hrtimer_init_on_stack(&t.timer, restart->nanosleep.clockid,
1721				HRTIMER_MODE_ABS);
1722	hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
1723
1724	ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
1725	destroy_hrtimer_on_stack(&t.timer);
1726	return ret;
1727}
1728
1729long hrtimer_nanosleep(const struct timespec64 *rqtp,
1730		       const enum hrtimer_mode mode, const clockid_t clockid)
1731{
1732	struct restart_block *restart;
1733	struct hrtimer_sleeper t;
1734	int ret = 0;
1735	u64 slack;
1736
1737	slack = current->timer_slack_ns;
1738	if (dl_task(current) || rt_task(current))
1739		slack = 0;
1740
1741	hrtimer_init_on_stack(&t.timer, clockid, mode);
1742	hrtimer_set_expires_range_ns(&t.timer, timespec64_to_ktime(*rqtp), slack);
1743	ret = do_nanosleep(&t, mode);
1744	if (ret != -ERESTART_RESTARTBLOCK)
1745		goto out;
1746
1747	/* Absolute timers do not update the rmtp value and restart: */
1748	if (mode == HRTIMER_MODE_ABS) {
1749		ret = -ERESTARTNOHAND;
1750		goto out;
1751	}
1752
1753	restart = &current->restart_block;
1754	restart->fn = hrtimer_nanosleep_restart;
1755	restart->nanosleep.clockid = t.timer.base->clockid;
1756	restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
1757out:
1758	destroy_hrtimer_on_stack(&t.timer);
1759	return ret;
1760}
1761
1762SYSCALL_DEFINE2(nanosleep, struct timespec __user *, rqtp,
1763		struct timespec __user *, rmtp)
 
 
1764{
1765	struct timespec64 tu;
1766
1767	if (get_timespec64(&tu, rqtp))
1768		return -EFAULT;
1769
1770	if (!timespec64_valid(&tu))
1771		return -EINVAL;
1772
1773	current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
1774	current->restart_block.nanosleep.rmtp = rmtp;
1775	return hrtimer_nanosleep(&tu, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
 
1776}
1777
1778#ifdef CONFIG_COMPAT
 
 
1779
1780COMPAT_SYSCALL_DEFINE2(nanosleep, struct compat_timespec __user *, rqtp,
1781		       struct compat_timespec __user *, rmtp)
1782{
1783	struct timespec64 tu;
1784
1785	if (compat_get_timespec64(&tu, rqtp))
1786		return -EFAULT;
1787
1788	if (!timespec64_valid(&tu))
1789		return -EINVAL;
1790
1791	current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
1792	current->restart_block.nanosleep.compat_rmtp = rmtp;
1793	return hrtimer_nanosleep(&tu, HRTIMER_MODE_REL, CLOCK_MONOTONIC);
 
1794}
1795#endif
1796
1797/*
1798 * Functions related to boot-time initialization:
1799 */
1800int hrtimers_prepare_cpu(unsigned int cpu)
1801{
1802	struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
1803	int i;
1804
1805	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1806		cpu_base->clock_base[i].cpu_base = cpu_base;
1807		timerqueue_init_head(&cpu_base->clock_base[i].active);
 
 
 
1808	}
1809
1810	cpu_base->cpu = cpu;
1811	cpu_base->active_bases = 0;
1812	cpu_base->hres_active = 0;
1813	cpu_base->hang_detected = 0;
1814	cpu_base->next_timer = NULL;
1815	cpu_base->softirq_next_timer = NULL;
1816	cpu_base->expires_next = KTIME_MAX;
1817	cpu_base->softirq_expires_next = KTIME_MAX;
 
1818	return 0;
1819}
1820
1821#ifdef CONFIG_HOTPLUG_CPU
1822
1823static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
1824				struct hrtimer_clock_base *new_base)
1825{
1826	struct hrtimer *timer;
1827	struct timerqueue_node *node;
1828
1829	while ((node = timerqueue_getnext(&old_base->active))) {
1830		timer = container_of(node, struct hrtimer, node);
1831		BUG_ON(hrtimer_callback_running(timer));
1832		debug_deactivate(timer);
1833
1834		/*
1835		 * Mark it as ENQUEUED not INACTIVE otherwise the
1836		 * timer could be seen as !active and just vanish away
1837		 * under us on another CPU
1838		 */
1839		__remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
1840		timer->base = new_base;
1841		/*
1842		 * Enqueue the timers on the new cpu. This does not
1843		 * reprogram the event device in case the timer
1844		 * expires before the earliest on this CPU, but we run
1845		 * hrtimer_interrupt after we migrated everything to
1846		 * sort out already expired timers and reprogram the
1847		 * event device.
1848		 */
1849		enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
1850	}
1851}
1852
1853int hrtimers_dead_cpu(unsigned int scpu)
1854{
1855	struct hrtimer_cpu_base *old_base, *new_base;
1856	int i;
1857
1858	BUG_ON(cpu_online(scpu));
1859	tick_cancel_sched_timer(scpu);
1860
1861	/*
1862	 * this BH disable ensures that raise_softirq_irqoff() does
1863	 * not wakeup ksoftirqd (and acquire the pi-lock) while
1864	 * holding the cpu_base lock
1865	 */
1866	local_bh_disable();
1867	local_irq_disable();
1868	old_base = &per_cpu(hrtimer_bases, scpu);
1869	new_base = this_cpu_ptr(&hrtimer_bases);
1870	/*
1871	 * The caller is globally serialized and nobody else
1872	 * takes two locks at once, deadlock is not possible.
1873	 */
1874	raw_spin_lock(&new_base->lock);
1875	raw_spin_lock_nested(&old_base->lock, SINGLE_DEPTH_NESTING);
1876
1877	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
1878		migrate_hrtimer_list(&old_base->clock_base[i],
1879				     &new_base->clock_base[i]);
1880	}
1881
1882	/*
1883	 * The migration might have changed the first expiring softirq
1884	 * timer on this CPU. Update it.
1885	 */
1886	hrtimer_update_softirq_timer(new_base, false);
1887
1888	raw_spin_unlock(&old_base->lock);
1889	raw_spin_unlock(&new_base->lock);
1890
1891	/* Check, if we got expired work to do */
1892	__hrtimer_peek_ahead_timers();
1893	local_irq_enable();
1894	local_bh_enable();
1895	return 0;
1896}
1897
1898#endif /* CONFIG_HOTPLUG_CPU */
1899
1900void __init hrtimers_init(void)
1901{
1902	hrtimers_prepare_cpu(smp_processor_id());
1903	open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
1904}
1905
1906/**
1907 * schedule_hrtimeout_range_clock - sleep until timeout
1908 * @expires:	timeout value (ktime_t)
1909 * @delta:	slack in expires timeout (ktime_t)
1910 * @mode:	timer mode
1911 * @clock_id:	timer clock to be used
1912 */
1913int __sched
1914schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
1915			       const enum hrtimer_mode mode, clockid_t clock_id)
1916{
1917	struct hrtimer_sleeper t;
1918
1919	/*
1920	 * Optimize when a zero timeout value is given. It does not
1921	 * matter whether this is an absolute or a relative time.
1922	 */
1923	if (expires && *expires == 0) {
1924		__set_current_state(TASK_RUNNING);
1925		return 0;
1926	}
1927
1928	/*
1929	 * A NULL parameter means "infinite"
1930	 */
1931	if (!expires) {
1932		schedule();
1933		return -EINTR;
1934	}
1935
1936	hrtimer_init_on_stack(&t.timer, clock_id, mode);
1937	hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
1938
1939	hrtimer_init_sleeper(&t, current);
1940
1941	hrtimer_start_expires(&t.timer, mode);
1942
1943	if (likely(t.task))
1944		schedule();
1945
1946	hrtimer_cancel(&t.timer);
1947	destroy_hrtimer_on_stack(&t.timer);
1948
1949	__set_current_state(TASK_RUNNING);
1950
1951	return !t.task ? 0 : -EINTR;
1952}
1953
1954/**
1955 * schedule_hrtimeout_range - sleep until timeout
1956 * @expires:	timeout value (ktime_t)
1957 * @delta:	slack in expires timeout (ktime_t)
1958 * @mode:	timer mode
1959 *
1960 * Make the current task sleep until the given expiry time has
1961 * elapsed. The routine will return immediately unless
1962 * the current task state has been set (see set_current_state()).
1963 *
1964 * The @delta argument gives the kernel the freedom to schedule the
1965 * actual wakeup to a time that is both power and performance friendly.
1966 * The kernel give the normal best effort behavior for "@expires+@delta",
1967 * but may decide to fire the timer earlier, but no earlier than @expires.
1968 *
1969 * You can set the task state as follows -
1970 *
1971 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
1972 * pass before the routine returns unless the current task is explicitly
1973 * woken up, (e.g. by wake_up_process()).
1974 *
1975 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
1976 * delivered to the current task or the current task is explicitly woken
1977 * up.
1978 *
1979 * The current task state is guaranteed to be TASK_RUNNING when this
1980 * routine returns.
1981 *
1982 * Returns 0 when the timer has expired. If the task was woken before the
1983 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
1984 * by an explicit wakeup, it returns -EINTR.
1985 */
1986int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
1987				     const enum hrtimer_mode mode)
1988{
1989	return schedule_hrtimeout_range_clock(expires, delta, mode,
1990					      CLOCK_MONOTONIC);
1991}
1992EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
1993
1994/**
1995 * schedule_hrtimeout - sleep until timeout
1996 * @expires:	timeout value (ktime_t)
1997 * @mode:	timer mode
1998 *
1999 * Make the current task sleep until the given expiry time has
2000 * elapsed. The routine will return immediately unless
2001 * the current task state has been set (see set_current_state()).
2002 *
2003 * You can set the task state as follows -
2004 *
2005 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2006 * pass before the routine returns unless the current task is explicitly
2007 * woken up, (e.g. by wake_up_process()).
2008 *
2009 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2010 * delivered to the current task or the current task is explicitly woken
2011 * up.
2012 *
2013 * The current task state is guaranteed to be TASK_RUNNING when this
2014 * routine returns.
2015 *
2016 * Returns 0 when the timer has expired. If the task was woken before the
2017 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2018 * by an explicit wakeup, it returns -EINTR.
2019 */
2020int __sched schedule_hrtimeout(ktime_t *expires,
2021			       const enum hrtimer_mode mode)
2022{
2023	return schedule_hrtimeout_range(expires, 0, mode);
2024}
2025EXPORT_SYMBOL_GPL(schedule_hrtimeout);