1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 *  Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
   4 *  Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
   5 *  Copyright(C) 2006-2007  Timesys Corp., Thomas Gleixner
   6 *
   7 *  High-resolution kernel timers
   8 *
   9 *  In contrast to the low-resolution timeout API, aka timer wheel,
  10 *  hrtimers provide finer resolution and accuracy depending on system
  11 *  configuration and capabilities.
  12 *
  13 *  Started by: Thomas Gleixner and Ingo Molnar
  14 *
  15 *  Credits:
  16 *	Based on the original timer wheel code
  17 *
  18 *	Help, testing, suggestions, bugfixes, improvements were
  19 *	provided by:
  20 *
  21 *	George Anzinger, Andrew Morton, Steven Rostedt, Roman Zippel
  22 *	et. al.
  23 */
  24
  25#include <linux/cpu.h>
  26#include <linux/export.h>
  27#include <linux/percpu.h>
  28#include <linux/hrtimer.h>
  29#include <linux/notifier.h>
  30#include <linux/syscalls.h>
  31#include <linux/interrupt.h>
  32#include <linux/tick.h>
  33#include <linux/err.h>
  34#include <linux/debugobjects.h>
  35#include <linux/sched/signal.h>
  36#include <linux/sched/sysctl.h>
  37#include <linux/sched/rt.h>
  38#include <linux/sched/deadline.h>
  39#include <linux/sched/nohz.h>
  40#include <linux/sched/debug.h>
  41#include <linux/sched/isolation.h>
  42#include <linux/timer.h>
  43#include <linux/freezer.h>
  44#include <linux/compat.h>
  45
  46#include <linux/uaccess.h>
  47
  48#include <trace/events/timer.h>
  49
  50#include "tick-internal.h"
  51
  52/*
  53 * Masks for selecting the soft and hard context timers from
  54 * cpu_base->active
  55 */
  56#define MASK_SHIFT		(HRTIMER_BASE_MONOTONIC_SOFT)
  57#define HRTIMER_ACTIVE_HARD	((1U << MASK_SHIFT) - 1)
  58#define HRTIMER_ACTIVE_SOFT	(HRTIMER_ACTIVE_HARD << MASK_SHIFT)
  59#define HRTIMER_ACTIVE_ALL	(HRTIMER_ACTIVE_SOFT | HRTIMER_ACTIVE_HARD)
  60
  61/*
  62 * The timer bases:
  63 *
  64 * There are more clockids than hrtimer bases. Thus, we index
  65 * into the timer bases by the hrtimer_base_type enum. When trying
  66 * to reach a base using a clockid, hrtimer_clockid_to_base()
  67 * is used to convert from clockid to the proper hrtimer_base_type.
  68 */
  69DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
  70{
  71	.lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
  72	.clock_base =
  73	{
  74		{
  75			.index = HRTIMER_BASE_MONOTONIC,
  76			.clockid = CLOCK_MONOTONIC,
  77			.get_time = &ktime_get,
  78		},
  79		{
  80			.index = HRTIMER_BASE_REALTIME,
  81			.clockid = CLOCK_REALTIME,
  82			.get_time = &ktime_get_real,
  83		},
  84		{
  85			.index = HRTIMER_BASE_BOOTTIME,
  86			.clockid = CLOCK_BOOTTIME,
  87			.get_time = &ktime_get_boottime,
  88		},
  89		{
  90			.index = HRTIMER_BASE_TAI,
  91			.clockid = CLOCK_TAI,
  92			.get_time = &ktime_get_clocktai,
  93		},
  94		{
  95			.index = HRTIMER_BASE_MONOTONIC_SOFT,
  96			.clockid = CLOCK_MONOTONIC,
  97			.get_time = &ktime_get,
  98		},
  99		{
 100			.index = HRTIMER_BASE_REALTIME_SOFT,
 101			.clockid = CLOCK_REALTIME,
 102			.get_time = &ktime_get_real,
 103		},
 104		{
 105			.index = HRTIMER_BASE_BOOTTIME_SOFT,
 106			.clockid = CLOCK_BOOTTIME,
 107			.get_time = &ktime_get_boottime,
 108		},
 109		{
 110			.index = HRTIMER_BASE_TAI_SOFT,
 111			.clockid = CLOCK_TAI,
 112			.get_time = &ktime_get_clocktai,
 113		},
 114	}
 115};
 116
 117static const int hrtimer_clock_to_base_table[MAX_CLOCKS] = {
 118	/* Make sure we catch unsupported clockids */
 119	[0 ... MAX_CLOCKS - 1]	= HRTIMER_MAX_CLOCK_BASES,
 120
 121	[CLOCK_REALTIME]	= HRTIMER_BASE_REALTIME,
 122	[CLOCK_MONOTONIC]	= HRTIMER_BASE_MONOTONIC,
 123	[CLOCK_BOOTTIME]	= HRTIMER_BASE_BOOTTIME,
 124	[CLOCK_TAI]		= HRTIMER_BASE_TAI,
 125};
 126
 127/*
 128 * Functions and macros which are different for UP/SMP systems are kept in a
 129 * single place
 130 */
 131#ifdef CONFIG_SMP
 132
 133/*
 134 * We require the migration_base for lock_hrtimer_base()/switch_hrtimer_base()
 135 * such that hrtimer_callback_running() can unconditionally dereference
 136 * timer->base->cpu_base
 137 */
 138static struct hrtimer_cpu_base migration_cpu_base = {
 139	.clock_base = { {
 140		.cpu_base = &migration_cpu_base,
 141		.seq      = SEQCNT_RAW_SPINLOCK_ZERO(migration_cpu_base.seq,
 142						     &migration_cpu_base.lock),
 143	}, },
 144};
 145
 146#define migration_base	migration_cpu_base.clock_base[0]
 147
 148static inline bool is_migration_base(struct hrtimer_clock_base *base)
 149{
 150	return base == &migration_base;
 151}
 152
 153/*
 154 * We are using hashed locking: holding per_cpu(hrtimer_bases)[n].lock
 155 * means that all timers which are tied to this base via timer->base are
 156 * locked, and the base itself is locked too.
 157 *
 158 * So __run_timers/migrate_timers can safely modify all timers which could
 159 * be found on the lists/queues.
 160 *
 161 * When the timer's base is locked, and the timer removed from list, it is
 162 * possible to set timer->base = &migration_base and drop the lock: the timer
 163 * remains locked.
 164 */
 165static
 166struct hrtimer_clock_base *lock_hrtimer_base(const struct hrtimer *timer,
 167					     unsigned long *flags)
 168	__acquires(&timer->base->lock)
 169{
 170	struct hrtimer_clock_base *base;
 171
 172	for (;;) {
 173		base = READ_ONCE(timer->base);
 174		if (likely(base != &migration_base)) {
 175			raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
 176			if (likely(base == timer->base))
 177				return base;
 178			/* The timer has migrated to another CPU: */
 179			raw_spin_unlock_irqrestore(&base->cpu_base->lock, *flags);
 180		}
 181		cpu_relax();
 182	}
 183}
 184
 185/*
 186 * We do not migrate the timer when it is expiring before the next
 187 * event on the target cpu. When high resolution is enabled, we cannot
 188 * reprogram the target cpu hardware and we would cause it to fire
 189 * late. To keep it simple, we handle the high resolution enabled and
 190 * disabled case similar.
 191 *
 192 * Called with cpu_base->lock of target cpu held.
 193 */
 194static int
 195hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base)
 196{
 197	ktime_t expires;
 198
 199	expires = ktime_sub(hrtimer_get_expires(timer), new_base->offset);
 200	return expires < new_base->cpu_base->expires_next;
 201}
 202
 203static inline
 204struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
 205					 int pinned)
 206{
 207#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON)
 208	if (static_branch_likely(&timers_migration_enabled) && !pinned)
 209		return &per_cpu(hrtimer_bases, get_nohz_timer_target());
 210#endif
 211	return base;
 212}
 213
 214/*
 215 * We switch the timer base to a power-optimized selected CPU target,
 216 * if:
 217 *	- NO_HZ_COMMON is enabled
 218 *	- timer migration is enabled
 219 *	- the timer callback is not running
 220 *	- the timer is not the first expiring timer on the new target
 221 *
 222 * If one of the above requirements is not fulfilled we move the timer
 223 * to the current CPU or leave it on the previously assigned CPU if
 224 * the timer callback is currently running.
 225 */
 226static inline struct hrtimer_clock_base *
 227switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
 228		    int pinned)
 229{
 230	struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
 231	struct hrtimer_clock_base *new_base;
 232	int basenum = base->index;
 233
 234	this_cpu_base = this_cpu_ptr(&hrtimer_bases);
 235	new_cpu_base = get_target_base(this_cpu_base, pinned);
 236again:
 237	new_base = &new_cpu_base->clock_base[basenum];
 238
 239	if (base != new_base) {
 240		/*
 241		 * We are trying to move timer to new_base.
 242		 * However we can't change timer's base while it is running,
 243		 * so we keep it on the same CPU. No hassle vs. reprogramming
 244		 * the event source in the high resolution case. The softirq
 245		 * code will take care of this when the timer function has
 246		 * completed. There is no conflict as we hold the lock until
 247		 * the timer is enqueued.
 248		 */
 249		if (unlikely(hrtimer_callback_running(timer)))
 250			return base;
 251
 252		/* See the comment in lock_hrtimer_base() */
 253		WRITE_ONCE(timer->base, &migration_base);
 254		raw_spin_unlock(&base->cpu_base->lock);
 255		raw_spin_lock(&new_base->cpu_base->lock);
 256
 257		if (new_cpu_base != this_cpu_base &&
 258		    hrtimer_check_target(timer, new_base)) {
 259			raw_spin_unlock(&new_base->cpu_base->lock);
 260			raw_spin_lock(&base->cpu_base->lock);
 261			new_cpu_base = this_cpu_base;
 262			WRITE_ONCE(timer->base, base);
 263			goto again;
 264		}
 265		WRITE_ONCE(timer->base, new_base);
 266	} else {
 267		if (new_cpu_base != this_cpu_base &&
 268		    hrtimer_check_target(timer, new_base)) {
 269			new_cpu_base = this_cpu_base;
 270			goto again;
 271		}
 272	}
 273	return new_base;
 274}
 275
 276#else /* CONFIG_SMP */
 277
 278static inline bool is_migration_base(struct hrtimer_clock_base *base)
 279{
 280	return false;
 281}
 282
 283static inline struct hrtimer_clock_base *
 284lock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
 285	__acquires(&timer->base->cpu_base->lock)
 286{
 287	struct hrtimer_clock_base *base = timer->base;
 288
 289	raw_spin_lock_irqsave(&base->cpu_base->lock, *flags);
 290
 291	return base;
 292}
 293
 294# define switch_hrtimer_base(t, b, p)	(b)
 295
 296#endif	/* !CONFIG_SMP */
 297
 298/*
 299 * Functions for the union type storage format of ktime_t which are
 300 * too large for inlining:
 301 */
 302#if BITS_PER_LONG < 64
 303/*
 304 * Divide a ktime value by a nanosecond value
 305 */
 306s64 __ktime_divns(const ktime_t kt, s64 div)
 307{
 308	int sft = 0;
 309	s64 dclc;
 310	u64 tmp;
 311
 312	dclc = ktime_to_ns(kt);
 313	tmp = dclc < 0 ? -dclc : dclc;
 314
 315	/* Make sure the divisor is less than 2^32: */
 316	while (div >> 32) {
 317		sft++;
 318		div >>= 1;
 319	}
 320	tmp >>= sft;
 321	do_div(tmp, (u32) div);
 322	return dclc < 0 ? -tmp : tmp;
 323}
 324EXPORT_SYMBOL_GPL(__ktime_divns);
 325#endif /* BITS_PER_LONG >= 64 */
 326
 327/*
 328 * Add two ktime values and do a safety check for overflow:
 329 */
 330ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
 331{
 332	ktime_t res = ktime_add_unsafe(lhs, rhs);
 333
 334	/*
 335	 * We use KTIME_SEC_MAX here, the maximum timeout which we can
 336	 * return to user space in a timespec:
 337	 */
 338	if (res < 0 || res < lhs || res < rhs)
 339		res = ktime_set(KTIME_SEC_MAX, 0);
 340
 341	return res;
 342}
 343
 344EXPORT_SYMBOL_GPL(ktime_add_safe);
 345
 346#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 347
 348static const struct debug_obj_descr hrtimer_debug_descr;
 349
 350static void *hrtimer_debug_hint(void *addr)
 351{
 352	return ((struct hrtimer *) addr)->function;
 353}
 354
 355/*
 356 * fixup_init is called when:
 357 * - an active object is initialized
 358 */
 359static bool hrtimer_fixup_init(void *addr, enum debug_obj_state state)
 360{
 361	struct hrtimer *timer = addr;
 362
 363	switch (state) {
 364	case ODEBUG_STATE_ACTIVE:
 365		hrtimer_cancel(timer);
 366		debug_object_init(timer, &hrtimer_debug_descr);
 367		return true;
 368	default:
 369		return false;
 370	}
 371}
 372
 373/*
 374 * fixup_activate is called when:
 375 * - an active object is activated
 376 * - an unknown non-static object is activated
 377 */
 378static bool hrtimer_fixup_activate(void *addr, enum debug_obj_state state)
 379{
 380	switch (state) {
 381	case ODEBUG_STATE_ACTIVE:
 382		WARN_ON(1);
 383		fallthrough;
 384	default:
 385		return false;
 386	}
 387}
 388
 389/*
 390 * fixup_free is called when:
 391 * - an active object is freed
 392 */
 393static bool hrtimer_fixup_free(void *addr, enum debug_obj_state state)
 394{
 395	struct hrtimer *timer = addr;
 396
 397	switch (state) {
 398	case ODEBUG_STATE_ACTIVE:
 399		hrtimer_cancel(timer);
 400		debug_object_free(timer, &hrtimer_debug_descr);
 401		return true;
 402	default:
 403		return false;
 404	}
 405}
 406
 407static const struct debug_obj_descr hrtimer_debug_descr = {
 408	.name		= "hrtimer",
 409	.debug_hint	= hrtimer_debug_hint,
 410	.fixup_init	= hrtimer_fixup_init,
 411	.fixup_activate	= hrtimer_fixup_activate,
 412	.fixup_free	= hrtimer_fixup_free,
 413};
 414
 415static inline void debug_hrtimer_init(struct hrtimer *timer)
 416{
 417	debug_object_init(timer, &hrtimer_debug_descr);
 418}
 419
 420static inline void debug_hrtimer_activate(struct hrtimer *timer,
 421					  enum hrtimer_mode mode)
 422{
 423	debug_object_activate(timer, &hrtimer_debug_descr);
 424}
 425
 426static inline void debug_hrtimer_deactivate(struct hrtimer *timer)
 427{
 428	debug_object_deactivate(timer, &hrtimer_debug_descr);
 429}
 430
 
 
 
 
 
 431static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 432			   enum hrtimer_mode mode);
 433
 434void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t clock_id,
 435			   enum hrtimer_mode mode)
 436{
 437	debug_object_init_on_stack(timer, &hrtimer_debug_descr);
 438	__hrtimer_init(timer, clock_id, mode);
 439}
 440EXPORT_SYMBOL_GPL(hrtimer_init_on_stack);
 441
 442static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 443				   clockid_t clock_id, enum hrtimer_mode mode);
 444
 445void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
 446				   clockid_t clock_id, enum hrtimer_mode mode)
 447{
 448	debug_object_init_on_stack(&sl->timer, &hrtimer_debug_descr);
 449	__hrtimer_init_sleeper(sl, clock_id, mode);
 450}
 451EXPORT_SYMBOL_GPL(hrtimer_init_sleeper_on_stack);
 452
 453void destroy_hrtimer_on_stack(struct hrtimer *timer)
 454{
 455	debug_object_free(timer, &hrtimer_debug_descr);
 456}
 457EXPORT_SYMBOL_GPL(destroy_hrtimer_on_stack);
 458
 459#else
 460
 461static inline void debug_hrtimer_init(struct hrtimer *timer) { }
 462static inline void debug_hrtimer_activate(struct hrtimer *timer,
 463					  enum hrtimer_mode mode) { }
 464static inline void debug_hrtimer_deactivate(struct hrtimer *timer) { }
 465#endif
 466
 467static inline void
 468debug_init(struct hrtimer *timer, clockid_t clockid,
 469	   enum hrtimer_mode mode)
 470{
 471	debug_hrtimer_init(timer);
 472	trace_hrtimer_init(timer, clockid, mode);
 473}
 474
 475static inline void debug_activate(struct hrtimer *timer,
 476				  enum hrtimer_mode mode)
 477{
 478	debug_hrtimer_activate(timer, mode);
 479	trace_hrtimer_start(timer, mode);
 480}
 481
 482static inline void debug_deactivate(struct hrtimer *timer)
 483{
 484	debug_hrtimer_deactivate(timer);
 485	trace_hrtimer_cancel(timer);
 486}
 487
 488static struct hrtimer_clock_base *
 489__next_base(struct hrtimer_cpu_base *cpu_base, unsigned int *active)
 490{
 491	unsigned int idx;
 492
 493	if (!*active)
 494		return NULL;
 495
 496	idx = __ffs(*active);
 497	*active &= ~(1U << idx);
 498
 499	return &cpu_base->clock_base[idx];
 500}
 501
 502#define for_each_active_base(base, cpu_base, active)	\
 503	while ((base = __next_base((cpu_base), &(active))))
 504
 505static ktime_t __hrtimer_next_event_base(struct hrtimer_cpu_base *cpu_base,
 506					 const struct hrtimer *exclude,
 507					 unsigned int active,
 508					 ktime_t expires_next)
 509{
 510	struct hrtimer_clock_base *base;
 511	ktime_t expires;
 512
 513	for_each_active_base(base, cpu_base, active) {
 514		struct timerqueue_node *next;
 515		struct hrtimer *timer;
 516
 517		next = timerqueue_getnext(&base->active);
 518		timer = container_of(next, struct hrtimer, node);
 519		if (timer == exclude) {
 520			/* Get to the next timer in the queue. */
 521			next = timerqueue_iterate_next(next);
 522			if (!next)
 523				continue;
 524
 525			timer = container_of(next, struct hrtimer, node);
 526		}
 527		expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
 528		if (expires < expires_next) {
 529			expires_next = expires;
 530
 531			/* Skip cpu_base update if a timer is being excluded. */
 532			if (exclude)
 533				continue;
 534
 535			if (timer->is_soft)
 536				cpu_base->softirq_next_timer = timer;
 537			else
 538				cpu_base->next_timer = timer;
 539		}
 540	}
 541	/*
 542	 * clock_was_set() might have changed base->offset of any of
 543	 * the clock bases so the result might be negative. Fix it up
 544	 * to prevent a false positive in clockevents_program_event().
 545	 */
 546	if (expires_next < 0)
 547		expires_next = 0;
 548	return expires_next;
 549}
 550
 551/*
 552 * Recomputes cpu_base::*next_timer and returns the earliest expires_next
 553 * but does not set cpu_base::*expires_next, that is done by
 554 * hrtimer[_force]_reprogram and hrtimer_interrupt only. When updating
 555 * cpu_base::*expires_next right away, reprogramming logic would no longer
 556 * work.
 557 *
 558 * When a softirq is pending, we can ignore the HRTIMER_ACTIVE_SOFT bases,
 559 * those timers will get run whenever the softirq gets handled, at the end of
 560 * hrtimer_run_softirq(), hrtimer_update_softirq_timer() will re-add these bases.
 561 *
 562 * Therefore softirq values are those from the HRTIMER_ACTIVE_SOFT clock bases.
 563 * The !softirq values are the minima across HRTIMER_ACTIVE_ALL, unless an actual
 564 * softirq is pending, in which case they're the minima of HRTIMER_ACTIVE_HARD.
 565 *
 566 * @active_mask must be one of:
 567 *  - HRTIMER_ACTIVE_ALL,
 568 *  - HRTIMER_ACTIVE_SOFT, or
 569 *  - HRTIMER_ACTIVE_HARD.
 570 */
 571static ktime_t
 572__hrtimer_get_next_event(struct hrtimer_cpu_base *cpu_base, unsigned int active_mask)
 573{
 574	unsigned int active;
 575	struct hrtimer *next_timer = NULL;
 576	ktime_t expires_next = KTIME_MAX;
 577
 578	if (!cpu_base->softirq_activated && (active_mask & HRTIMER_ACTIVE_SOFT)) {
 579		active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
 580		cpu_base->softirq_next_timer = NULL;
 581		expires_next = __hrtimer_next_event_base(cpu_base, NULL,
 582							 active, KTIME_MAX);
 583
 584		next_timer = cpu_base->softirq_next_timer;
 585	}
 586
 587	if (active_mask & HRTIMER_ACTIVE_HARD) {
 588		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
 589		cpu_base->next_timer = next_timer;
 590		expires_next = __hrtimer_next_event_base(cpu_base, NULL, active,
 591							 expires_next);
 592	}
 593
 594	return expires_next;
 595}
 596
 597static ktime_t hrtimer_update_next_event(struct hrtimer_cpu_base *cpu_base)
 598{
 599	ktime_t expires_next, soft = KTIME_MAX;
 600
 601	/*
 602	 * If the soft interrupt has already been activated, ignore the
 603	 * soft bases. They will be handled in the already raised soft
 604	 * interrupt.
 605	 */
 606	if (!cpu_base->softirq_activated) {
 607		soft = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
 608		/*
 609		 * Update the soft expiry time. clock_settime() might have
 610		 * affected it.
 611		 */
 612		cpu_base->softirq_expires_next = soft;
 613	}
 614
 615	expires_next = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_HARD);
 616	/*
 617	 * If a softirq timer is expiring first, update cpu_base->next_timer
 618	 * and program the hardware with the soft expiry time.
 619	 */
 620	if (expires_next > soft) {
 621		cpu_base->next_timer = cpu_base->softirq_next_timer;
 622		expires_next = soft;
 623	}
 624
 625	return expires_next;
 626}
 627
 628static inline ktime_t hrtimer_update_base(struct hrtimer_cpu_base *base)
 629{
 630	ktime_t *offs_real = &base->clock_base[HRTIMER_BASE_REALTIME].offset;
 631	ktime_t *offs_boot = &base->clock_base[HRTIMER_BASE_BOOTTIME].offset;
 632	ktime_t *offs_tai = &base->clock_base[HRTIMER_BASE_TAI].offset;
 633
 634	ktime_t now = ktime_get_update_offsets_now(&base->clock_was_set_seq,
 635					    offs_real, offs_boot, offs_tai);
 636
 637	base->clock_base[HRTIMER_BASE_REALTIME_SOFT].offset = *offs_real;
 638	base->clock_base[HRTIMER_BASE_BOOTTIME_SOFT].offset = *offs_boot;
 639	base->clock_base[HRTIMER_BASE_TAI_SOFT].offset = *offs_tai;
 640
 641	return now;
 642}
 643
 644/*
 645 * Is the high resolution mode active ?
 646 */
 647static inline int __hrtimer_hres_active(struct hrtimer_cpu_base *cpu_base)
 648{
 649	return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
 650		cpu_base->hres_active : 0;
 651}
 652
 653static inline int hrtimer_hres_active(void)
 654{
 655	return __hrtimer_hres_active(this_cpu_ptr(&hrtimer_bases));
 656}
 657
 658static void __hrtimer_reprogram(struct hrtimer_cpu_base *cpu_base,
 659				struct hrtimer *next_timer,
 660				ktime_t expires_next)
 
 
 
 
 661{
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 662	cpu_base->expires_next = expires_next;
 663
 664	/*
 665	 * If hres is not active, hardware does not have to be
 666	 * reprogrammed yet.
 667	 *
 668	 * If a hang was detected in the last timer interrupt then we
 669	 * leave the hang delay active in the hardware. We want the
 670	 * system to make progress. That also prevents the following
 671	 * scenario:
 672	 * T1 expires 50ms from now
 673	 * T2 expires 5s from now
 674	 *
 675	 * T1 is removed, so this code is called and would reprogram
 676	 * the hardware to 5s from now. Any hrtimer_start after that
 677	 * will not reprogram the hardware due to hang_detected being
 678	 * set. So we'd effectively block all timers until the T2 event
 679	 * fires.
 680	 */
 681	if (!__hrtimer_hres_active(cpu_base) || cpu_base->hang_detected)
 682		return;
 683
 684	tick_program_event(expires_next, 1);
 685}
 686
 687/*
 688 * Reprogram the event source with checking both queues for the
 689 * next event
 690 * Called with interrupts disabled and base->lock held
 691 */
 692static void
 693hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
 694{
 695	ktime_t expires_next;
 696
 697	expires_next = hrtimer_update_next_event(cpu_base);
 698
 699	if (skip_equal && expires_next == cpu_base->expires_next)
 700		return;
 701
 702	__hrtimer_reprogram(cpu_base, cpu_base->next_timer, expires_next);
 703}
 704
 705/* High resolution timer related functions */
 706#ifdef CONFIG_HIGH_RES_TIMERS
 707
 708/*
 709 * High resolution timer enabled ?
 710 */
 711static bool hrtimer_hres_enabled __read_mostly  = true;
 712unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
 713EXPORT_SYMBOL_GPL(hrtimer_resolution);
 714
 715/*
 716 * Enable / Disable high resolution mode
 717 */
 718static int __init setup_hrtimer_hres(char *str)
 719{
 720	return (kstrtobool(str, &hrtimer_hres_enabled) == 0);
 721}
 722
 723__setup("highres=", setup_hrtimer_hres);
 724
 725/*
 726 * hrtimer_high_res_enabled - query, if the highres mode is enabled
 727 */
 728static inline int hrtimer_is_hres_enabled(void)
 729{
 730	return hrtimer_hres_enabled;
 731}
 732
 733static void retrigger_next_event(void *arg);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 734
 735/*
 736 * Switch to high resolution mode
 737 */
 738static void hrtimer_switch_to_hres(void)
 739{
 740	struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
 741
 742	if (tick_init_highres()) {
 743		pr_warn("Could not switch to high resolution mode on CPU %u\n",
 744			base->cpu);
 745		return;
 746	}
 747	base->hres_active = 1;
 748	hrtimer_resolution = HIGH_RES_NSEC;
 749
 750	tick_setup_sched_timer(true);
 751	/* "Retrigger" the interrupt to get things going */
 752	retrigger_next_event(NULL);
 753}
 754
 755#else
 
 
 
 756
 757static inline int hrtimer_is_hres_enabled(void) { return 0; }
 758static inline void hrtimer_switch_to_hres(void) { }
 759
 760#endif /* CONFIG_HIGH_RES_TIMERS */
 761/*
 762 * Retrigger next event is called after clock was set with interrupts
 763 * disabled through an SMP function call or directly from low level
 764 * resume code.
 765 *
 766 * This is only invoked when:
 767 *	- CONFIG_HIGH_RES_TIMERS is enabled.
 768 *	- CONFIG_NOHZ_COMMON is enabled
 769 *
 770 * For the other cases this function is empty and because the call sites
 771 * are optimized out it vanishes as well, i.e. no need for lots of
 772 * #ifdeffery.
 773 */
 774static void retrigger_next_event(void *arg)
 775{
 776	struct hrtimer_cpu_base *base = this_cpu_ptr(&hrtimer_bases);
 
 777
 778	/*
 779	 * When high resolution mode or nohz is active, then the offsets of
 780	 * CLOCK_REALTIME/TAI/BOOTTIME have to be updated. Otherwise the
 781	 * next tick will take care of that.
 782	 *
 783	 * If high resolution mode is active then the next expiring timer
 784	 * must be reevaluated and the clock event device reprogrammed if
 785	 * necessary.
 786	 *
 787	 * In the NOHZ case the update of the offset and the reevaluation
 788	 * of the next expiring timer is enough. The return from the SMP
 789	 * function call will take care of the reprogramming in case the
 790	 * CPU was in a NOHZ idle sleep.
 791	 */
 792	if (!__hrtimer_hres_active(base) && !tick_nohz_active)
 793		return;
 794
 795	raw_spin_lock(&base->lock);
 796	hrtimer_update_base(base);
 797	if (__hrtimer_hres_active(base))
 798		hrtimer_force_reprogram(base, 0);
 799	else
 800		hrtimer_update_next_event(base);
 801	raw_spin_unlock(&base->lock);
 802}
 803
 804/*
 805 * When a timer is enqueued and expires earlier than the already enqueued
 806 * timers, we have to check, whether it expires earlier than the timer for
 807 * which the clock event device was armed.
 808 *
 809 * Called with interrupts disabled and base->cpu_base.lock held
 810 */
 811static void hrtimer_reprogram(struct hrtimer *timer, bool reprogram)
 812{
 813	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
 814	struct hrtimer_clock_base *base = timer->base;
 815	ktime_t expires = ktime_sub(hrtimer_get_expires(timer), base->offset);
 816
 817	WARN_ON_ONCE(hrtimer_get_expires_tv64(timer) < 0);
 818
 819	/*
 820	 * CLOCK_REALTIME timer might be requested with an absolute
 821	 * expiry time which is less than base->offset. Set it to 0.
 822	 */
 823	if (expires < 0)
 824		expires = 0;
 825
 826	if (timer->is_soft) {
 827		/*
 828		 * soft hrtimer could be started on a remote CPU. In this
 829		 * case softirq_expires_next needs to be updated on the
 830		 * remote CPU. The soft hrtimer will not expire before the
 831		 * first hard hrtimer on the remote CPU -
 832		 * hrtimer_check_target() prevents this case.
 833		 */
 834		struct hrtimer_cpu_base *timer_cpu_base = base->cpu_base;
 835
 836		if (timer_cpu_base->softirq_activated)
 837			return;
 838
 839		if (!ktime_before(expires, timer_cpu_base->softirq_expires_next))
 840			return;
 841
 842		timer_cpu_base->softirq_next_timer = timer;
 843		timer_cpu_base->softirq_expires_next = expires;
 844
 845		if (!ktime_before(expires, timer_cpu_base->expires_next) ||
 846		    !reprogram)
 847			return;
 848	}
 849
 850	/*
 851	 * If the timer is not on the current cpu, we cannot reprogram
 852	 * the other cpus clock event device.
 853	 */
 854	if (base->cpu_base != cpu_base)
 855		return;
 856
 857	if (expires >= cpu_base->expires_next)
 858		return;
 859
 860	/*
 861	 * If the hrtimer interrupt is running, then it will reevaluate the
 862	 * clock bases and reprogram the clock event device.
 
 
 
 863	 */
 864	if (cpu_base->in_hrtirq)
 865		return;
 866
 867	cpu_base->next_timer = timer;
 868
 869	__hrtimer_reprogram(cpu_base, timer, expires);
 870}
 871
 872static bool update_needs_ipi(struct hrtimer_cpu_base *cpu_base,
 873			     unsigned int active)
 874{
 875	struct hrtimer_clock_base *base;
 876	unsigned int seq;
 877	ktime_t expires;
 878
 879	/*
 880	 * Update the base offsets unconditionally so the following
 881	 * checks whether the SMP function call is required works.
 882	 *
 883	 * The update is safe even when the remote CPU is in the hrtimer
 884	 * interrupt or the hrtimer soft interrupt and expiring affected
 885	 * bases. Either it will see the update before handling a base or
 886	 * it will see it when it finishes the processing and reevaluates
 887	 * the next expiring timer.
 888	 */
 889	seq = cpu_base->clock_was_set_seq;
 890	hrtimer_update_base(cpu_base);
 891
 892	/*
 893	 * If the sequence did not change over the update then the
 894	 * remote CPU already handled it.
 895	 */
 896	if (seq == cpu_base->clock_was_set_seq)
 897		return false;
 898
 899	/*
 900	 * If the remote CPU is currently handling an hrtimer interrupt, it
 901	 * will reevaluate the first expiring timer of all clock bases
 902	 * before reprogramming. Nothing to do here.
 903	 */
 904	if (cpu_base->in_hrtirq)
 905		return false;
 906
 907	/*
 908	 * Walk the affected clock bases and check whether the first expiring
 909	 * timer in a clock base is moving ahead of the first expiring timer of
 910	 * @cpu_base. If so, the IPI must be invoked because per CPU clock
 911	 * event devices cannot be remotely reprogrammed.
 912	 */
 913	active &= cpu_base->active_bases;
 914
 915	for_each_active_base(base, cpu_base, active) {
 916		struct timerqueue_node *next;
 917
 918		next = timerqueue_getnext(&base->active);
 919		expires = ktime_sub(next->expires, base->offset);
 920		if (expires < cpu_base->expires_next)
 921			return true;
 922
 923		/* Extra check for softirq clock bases */
 924		if (base->clockid < HRTIMER_BASE_MONOTONIC_SOFT)
 925			continue;
 926		if (cpu_base->softirq_activated)
 927			continue;
 928		if (expires < cpu_base->softirq_expires_next)
 929			return true;
 930	}
 931	return false;
 932}
 933
 934/*
 935 * Clock was set. This might affect CLOCK_REALTIME, CLOCK_TAI and
 936 * CLOCK_BOOTTIME (for late sleep time injection).
 937 *
 938 * This requires to update the offsets for these clocks
 939 * vs. CLOCK_MONOTONIC. When high resolution timers are enabled, then this
 940 * also requires to eventually reprogram the per CPU clock event devices
 941 * when the change moves an affected timer ahead of the first expiring
 942 * timer on that CPU. Obviously remote per CPU clock event devices cannot
 943 * be reprogrammed. The other reason why an IPI has to be sent is when the
 944 * system is in !HIGH_RES and NOHZ mode. The NOHZ mode updates the offsets
 945 * in the tick, which obviously might be stopped, so this has to bring out
 946 * the remote CPU which might sleep in idle to get this sorted.
 947 */
 948void clock_was_set(unsigned int bases)
 949{
 950	struct hrtimer_cpu_base *cpu_base = raw_cpu_ptr(&hrtimer_bases);
 951	cpumask_var_t mask;
 952	int cpu;
 953
 954	if (!__hrtimer_hres_active(cpu_base) && !tick_nohz_active)
 955		goto out_timerfd;
 956
 957	if (!zalloc_cpumask_var(&mask, GFP_KERNEL)) {
 958		on_each_cpu(retrigger_next_event, NULL, 1);
 959		goto out_timerfd;
 960	}
 961
 962	/* Avoid interrupting CPUs if possible */
 963	cpus_read_lock();
 964	for_each_online_cpu(cpu) {
 965		unsigned long flags;
 966
 967		cpu_base = &per_cpu(hrtimer_bases, cpu);
 968		raw_spin_lock_irqsave(&cpu_base->lock, flags);
 969
 970		if (update_needs_ipi(cpu_base, bases))
 971			cpumask_set_cpu(cpu, mask);
 972
 973		raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
 974	}
 975
 976	preempt_disable();
 977	smp_call_function_many(mask, retrigger_next_event, NULL, 1);
 978	preempt_enable();
 979	cpus_read_unlock();
 980	free_cpumask_var(mask);
 981
 982out_timerfd:
 983	timerfd_clock_was_set();
 984}
 985
 986static void clock_was_set_work(struct work_struct *work)
 987{
 988	clock_was_set(CLOCK_SET_WALL);
 989}
 990
 991static DECLARE_WORK(hrtimer_work, clock_was_set_work);
 992
 993/*
 994 * Called from timekeeping code to reprogram the hrtimer interrupt device
 995 * on all cpus and to notify timerfd.
 996 */
 997void clock_was_set_delayed(void)
 998{
 999	schedule_work(&hrtimer_work);
 
 
 
 
1000}
1001
1002/*
1003 * Called during resume either directly from via timekeeping_resume()
1004 * or in the case of s2idle from tick_unfreeze() to ensure that the
1005 * hrtimers are up to date.
 
1006 */
1007void hrtimers_resume_local(void)
1008{
1009	lockdep_assert_irqs_disabled();
1010	/* Retrigger on the local CPU */
1011	retrigger_next_event(NULL);
 
 
1012}
1013
1014/*
1015 * Counterpart to lock_hrtimer_base above:
1016 */
1017static inline
1018void unlock_hrtimer_base(const struct hrtimer *timer, unsigned long *flags)
1019	__releases(&timer->base->cpu_base->lock)
1020{
1021	raw_spin_unlock_irqrestore(&timer->base->cpu_base->lock, *flags);
1022}
1023
1024/**
1025 * hrtimer_forward() - forward the timer expiry
1026 * @timer:	hrtimer to forward
1027 * @now:	forward past this time
1028 * @interval:	the interval to forward
1029 *
1030 * Forward the timer expiry so it will expire in the future.
 
1031 *
1032 * .. note::
1033 *  This only updates the timer expiry value and does not requeue the timer.
1034 *
1035 * There is also a variant of the function hrtimer_forward_now().
1036 *
1037 * Context: Can be safely called from the callback function of @timer. If called
1038 *          from other contexts @timer must neither be enqueued nor running the
1039 *          callback and the caller needs to take care of serialization.
1040 *
1041 * Return: The number of overruns are returned.
 
1042 */
1043u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
1044{
1045	u64 orun = 1;
1046	ktime_t delta;
1047
1048	delta = ktime_sub(now, hrtimer_get_expires(timer));
1049
1050	if (delta < 0)
1051		return 0;
1052
1053	if (WARN_ON(timer->state & HRTIMER_STATE_ENQUEUED))
1054		return 0;
1055
1056	if (interval < hrtimer_resolution)
1057		interval = hrtimer_resolution;
1058
1059	if (unlikely(delta >= interval)) {
1060		s64 incr = ktime_to_ns(interval);
1061
1062		orun = ktime_divns(delta, incr);
1063		hrtimer_add_expires_ns(timer, incr * orun);
1064		if (hrtimer_get_expires_tv64(timer) > now)
1065			return orun;
1066		/*
1067		 * This (and the ktime_add() below) is the
1068		 * correction for exact:
1069		 */
1070		orun++;
1071	}
1072	hrtimer_add_expires(timer, interval);
1073
1074	return orun;
1075}
1076EXPORT_SYMBOL_GPL(hrtimer_forward);
1077
1078/*
1079 * enqueue_hrtimer - internal function to (re)start a timer
1080 *
1081 * The timer is inserted in expiry order. Insertion into the
1082 * red black tree is O(log(n)). Must hold the base lock.
1083 *
1084 * Returns 1 when the new timer is the leftmost timer in the tree.
1085 */
1086static int enqueue_hrtimer(struct hrtimer *timer,
1087			   struct hrtimer_clock_base *base,
1088			   enum hrtimer_mode mode)
1089{
1090	debug_activate(timer, mode);
1091	WARN_ON_ONCE(!base->cpu_base->online);
1092
1093	base->cpu_base->active_bases |= 1 << base->index;
1094
1095	/* Pairs with the lockless read in hrtimer_is_queued() */
1096	WRITE_ONCE(timer->state, HRTIMER_STATE_ENQUEUED);
1097
1098	return timerqueue_add(&base->active, &timer->node);
1099}
1100
1101/*
1102 * __remove_hrtimer - internal function to remove a timer
1103 *
1104 * Caller must hold the base lock.
1105 *
1106 * High resolution timer mode reprograms the clock event device when the
1107 * timer is the one which expires next. The caller can disable this by setting
1108 * reprogram to zero. This is useful, when the context does a reprogramming
1109 * anyway (e.g. timer interrupt)
1110 */
1111static void __remove_hrtimer(struct hrtimer *timer,
1112			     struct hrtimer_clock_base *base,
1113			     u8 newstate, int reprogram)
1114{
1115	struct hrtimer_cpu_base *cpu_base = base->cpu_base;
1116	u8 state = timer->state;
1117
1118	/* Pairs with the lockless read in hrtimer_is_queued() */
1119	WRITE_ONCE(timer->state, newstate);
1120	if (!(state & HRTIMER_STATE_ENQUEUED))
1121		return;
1122
1123	if (!timerqueue_del(&base->active, &timer->node))
1124		cpu_base->active_bases &= ~(1 << base->index);
1125
1126	/*
1127	 * Note: If reprogram is false we do not update
1128	 * cpu_base->next_timer. This happens when we remove the first
1129	 * timer on a remote cpu. No harm as we never dereference
1130	 * cpu_base->next_timer. So the worst thing what can happen is
1131	 * an superfluous call to hrtimer_force_reprogram() on the
1132	 * remote cpu later on if the same timer gets enqueued again.
1133	 */
1134	if (reprogram && timer == cpu_base->next_timer)
1135		hrtimer_force_reprogram(cpu_base, 1);
1136}
1137
1138/*
1139 * remove hrtimer, called with base lock held
1140 */
1141static inline int
1142remove_hrtimer(struct hrtimer *timer, struct hrtimer_clock_base *base,
1143	       bool restart, bool keep_local)
1144{
1145	u8 state = timer->state;
1146
1147	if (state & HRTIMER_STATE_ENQUEUED) {
1148		bool reprogram;
1149
1150		/*
1151		 * Remove the timer and force reprogramming when high
1152		 * resolution mode is active and the timer is on the current
1153		 * CPU. If we remove a timer on another CPU, reprogramming is
1154		 * skipped. The interrupt event on this CPU is fired and
1155		 * reprogramming happens in the interrupt handler. This is a
1156		 * rare case and less expensive than a smp call.
1157		 */
1158		debug_deactivate(timer);
1159		reprogram = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1160
1161		/*
1162		 * If the timer is not restarted then reprogramming is
1163		 * required if the timer is local. If it is local and about
1164		 * to be restarted, avoid programming it twice (on removal
1165		 * and a moment later when it's requeued).
1166		 */
1167		if (!restart)
1168			state = HRTIMER_STATE_INACTIVE;
1169		else
1170			reprogram &= !keep_local;
1171
1172		__remove_hrtimer(timer, base, state, reprogram);
1173		return 1;
1174	}
1175	return 0;
1176}
1177
1178static inline ktime_t hrtimer_update_lowres(struct hrtimer *timer, ktime_t tim,
1179					    const enum hrtimer_mode mode)
1180{
1181#ifdef CONFIG_TIME_LOW_RES
1182	/*
1183	 * CONFIG_TIME_LOW_RES indicates that the system has no way to return
1184	 * granular time values. For relative timers we add hrtimer_resolution
1185	 * (i.e. one jiffie) to prevent short timeouts.
1186	 */
1187	timer->is_rel = mode & HRTIMER_MODE_REL;
1188	if (timer->is_rel)
1189		tim = ktime_add_safe(tim, hrtimer_resolution);
1190#endif
1191	return tim;
1192}
1193
1194static void
1195hrtimer_update_softirq_timer(struct hrtimer_cpu_base *cpu_base, bool reprogram)
1196{
1197	ktime_t expires;
1198
1199	/*
1200	 * Find the next SOFT expiration.
1201	 */
1202	expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_SOFT);
1203
1204	/*
1205	 * reprogramming needs to be triggered, even if the next soft
1206	 * hrtimer expires at the same time than the next hard
1207	 * hrtimer. cpu_base->softirq_expires_next needs to be updated!
1208	 */
1209	if (expires == KTIME_MAX)
1210		return;
1211
1212	/*
1213	 * cpu_base->*next_timer is recomputed by __hrtimer_get_next_event()
1214	 * cpu_base->*expires_next is only set by hrtimer_reprogram()
1215	 */
1216	hrtimer_reprogram(cpu_base->softirq_next_timer, reprogram);
1217}
1218
1219static int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1220				    u64 delta_ns, const enum hrtimer_mode mode,
1221				    struct hrtimer_clock_base *base)
1222{
1223	struct hrtimer_clock_base *new_base;
1224	bool force_local, first;
1225
1226	/*
1227	 * If the timer is on the local cpu base and is the first expiring
1228	 * timer then this might end up reprogramming the hardware twice
1229	 * (on removal and on enqueue). To avoid that by prevent the
1230	 * reprogram on removal, keep the timer local to the current CPU
1231	 * and enforce reprogramming after it is queued no matter whether
1232	 * it is the new first expiring timer again or not.
1233	 */
1234	force_local = base->cpu_base == this_cpu_ptr(&hrtimer_bases);
1235	force_local &= base->cpu_base->next_timer == timer;
1236
1237	/*
1238	 * Remove an active timer from the queue. In case it is not queued
1239	 * on the current CPU, make sure that remove_hrtimer() updates the
1240	 * remote data correctly.
1241	 *
1242	 * If it's on the current CPU and the first expiring timer, then
1243	 * skip reprogramming, keep the timer local and enforce
1244	 * reprogramming later if it was the first expiring timer.  This
1245	 * avoids programming the underlying clock event twice (once at
1246	 * removal and once after enqueue).
1247	 */
1248	remove_hrtimer(timer, base, true, force_local);
1249
1250	if (mode & HRTIMER_MODE_REL)
1251		tim = ktime_add_safe(tim, base->get_time());
1252
1253	tim = hrtimer_update_lowres(timer, tim, mode);
1254
1255	hrtimer_set_expires_range_ns(timer, tim, delta_ns);
1256
1257	/* Switch the timer base, if necessary: */
1258	if (!force_local) {
1259		new_base = switch_hrtimer_base(timer, base,
1260					       mode & HRTIMER_MODE_PINNED);
1261	} else {
1262		new_base = base;
1263	}
1264
1265	first = enqueue_hrtimer(timer, new_base, mode);
1266	if (!force_local)
1267		return first;
1268
1269	/*
1270	 * Timer was forced to stay on the current CPU to avoid
1271	 * reprogramming on removal and enqueue. Force reprogram the
1272	 * hardware by evaluating the new first expiring timer.
1273	 */
1274	hrtimer_force_reprogram(new_base->cpu_base, 1);
1275	return 0;
1276}
1277
1278/**
1279 * hrtimer_start_range_ns - (re)start an hrtimer
1280 * @timer:	the timer to be added
1281 * @tim:	expiry time
1282 * @delta_ns:	"slack" range for the timer
1283 * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
1284 *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
1285 *		softirq based mode is considered for debug purpose only!
1286 */
1287void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
1288			    u64 delta_ns, const enum hrtimer_mode mode)
1289{
1290	struct hrtimer_clock_base *base;
1291	unsigned long flags;
1292
1293	/*
1294	 * Check whether the HRTIMER_MODE_SOFT bit and hrtimer.is_soft
1295	 * match on CONFIG_PREEMPT_RT = n. With PREEMPT_RT check the hard
1296	 * expiry mode because unmarked timers are moved to softirq expiry.
1297	 */
1298	if (!IS_ENABLED(CONFIG_PREEMPT_RT))
1299		WARN_ON_ONCE(!(mode & HRTIMER_MODE_SOFT) ^ !timer->is_soft);
1300	else
1301		WARN_ON_ONCE(!(mode & HRTIMER_MODE_HARD) ^ !timer->is_hard);
1302
1303	base = lock_hrtimer_base(timer, &flags);
1304
1305	if (__hrtimer_start_range_ns(timer, tim, delta_ns, mode, base))
1306		hrtimer_reprogram(timer, true);
1307
1308	unlock_hrtimer_base(timer, &flags);
1309}
1310EXPORT_SYMBOL_GPL(hrtimer_start_range_ns);
1311
1312/**
1313 * hrtimer_try_to_cancel - try to deactivate a timer
1314 * @timer:	hrtimer to stop
1315 *
1316 * Returns:
1317 *
1318 *  *  0 when the timer was not active
1319 *  *  1 when the timer was active
1320 *  * -1 when the timer is currently executing the callback function and
1321 *    cannot be stopped
1322 */
1323int hrtimer_try_to_cancel(struct hrtimer *timer)
1324{
1325	struct hrtimer_clock_base *base;
1326	unsigned long flags;
1327	int ret = -1;
1328
1329	/*
1330	 * Check lockless first. If the timer is not active (neither
1331	 * enqueued nor running the callback, nothing to do here.  The
1332	 * base lock does not serialize against a concurrent enqueue,
1333	 * so we can avoid taking it.
1334	 */
1335	if (!hrtimer_active(timer))
1336		return 0;
1337
1338	base = lock_hrtimer_base(timer, &flags);
1339
1340	if (!hrtimer_callback_running(timer))
1341		ret = remove_hrtimer(timer, base, false, false);
1342
1343	unlock_hrtimer_base(timer, &flags);
1344
1345	return ret;
1346
1347}
1348EXPORT_SYMBOL_GPL(hrtimer_try_to_cancel);
1349
1350#ifdef CONFIG_PREEMPT_RT
1351static void hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base)
1352{
1353	spin_lock_init(&base->softirq_expiry_lock);
1354}
1355
1356static void hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base)
1357{
1358	spin_lock(&base->softirq_expiry_lock);
1359}
1360
1361static void hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base)
1362{
1363	spin_unlock(&base->softirq_expiry_lock);
1364}
1365
1366/*
1367 * The counterpart to hrtimer_cancel_wait_running().
1368 *
1369 * If there is a waiter for cpu_base->expiry_lock, then it was waiting for
1370 * the timer callback to finish. Drop expiry_lock and reacquire it. That
1371 * allows the waiter to acquire the lock and make progress.
1372 */
1373static void hrtimer_sync_wait_running(struct hrtimer_cpu_base *cpu_base,
1374				      unsigned long flags)
1375{
1376	if (atomic_read(&cpu_base->timer_waiters)) {
1377		raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1378		spin_unlock(&cpu_base->softirq_expiry_lock);
1379		spin_lock(&cpu_base->softirq_expiry_lock);
1380		raw_spin_lock_irq(&cpu_base->lock);
1381	}
1382}
1383
1384/*
1385 * This function is called on PREEMPT_RT kernels when the fast path
1386 * deletion of a timer failed because the timer callback function was
1387 * running.
1388 *
1389 * This prevents priority inversion: if the soft irq thread is preempted
1390 * in the middle of a timer callback, then calling del_timer_sync() can
1391 * lead to two issues:
1392 *
1393 *  - If the caller is on a remote CPU then it has to spin wait for the timer
1394 *    handler to complete. This can result in unbound priority inversion.
1395 *
1396 *  - If the caller originates from the task which preempted the timer
1397 *    handler on the same CPU, then spin waiting for the timer handler to
1398 *    complete is never going to end.
1399 */
1400void hrtimer_cancel_wait_running(const struct hrtimer *timer)
1401{
1402	/* Lockless read. Prevent the compiler from reloading it below */
1403	struct hrtimer_clock_base *base = READ_ONCE(timer->base);
1404
1405	/*
1406	 * Just relax if the timer expires in hard interrupt context or if
1407	 * it is currently on the migration base.
1408	 */
1409	if (!timer->is_soft || is_migration_base(base)) {
1410		cpu_relax();
1411		return;
1412	}
1413
1414	/*
1415	 * Mark the base as contended and grab the expiry lock, which is
1416	 * held by the softirq across the timer callback. Drop the lock
1417	 * immediately so the softirq can expire the next timer. In theory
1418	 * the timer could already be running again, but that's more than
1419	 * unlikely and just causes another wait loop.
1420	 */
1421	atomic_inc(&base->cpu_base->timer_waiters);
1422	spin_lock_bh(&base->cpu_base->softirq_expiry_lock);
1423	atomic_dec(&base->cpu_base->timer_waiters);
1424	spin_unlock_bh(&base->cpu_base->softirq_expiry_lock);
1425}
1426#else
1427static inline void
1428hrtimer_cpu_base_init_expiry_lock(struct hrtimer_cpu_base *base) { }
1429static inline void
1430hrtimer_cpu_base_lock_expiry(struct hrtimer_cpu_base *base) { }
1431static inline void
1432hrtimer_cpu_base_unlock_expiry(struct hrtimer_cpu_base *base) { }
1433static inline void hrtimer_sync_wait_running(struct hrtimer_cpu_base *base,
1434					     unsigned long flags) { }
1435#endif
1436
1437/**
1438 * hrtimer_cancel - cancel a timer and wait for the handler to finish.
1439 * @timer:	the timer to be cancelled
1440 *
1441 * Returns:
1442 *  0 when the timer was not active
1443 *  1 when the timer was active
1444 */
1445int hrtimer_cancel(struct hrtimer *timer)
1446{
1447	int ret;
1448
1449	do {
1450		ret = hrtimer_try_to_cancel(timer);
1451
1452		if (ret < 0)
1453			hrtimer_cancel_wait_running(timer);
1454	} while (ret < 0);
1455	return ret;
1456}
1457EXPORT_SYMBOL_GPL(hrtimer_cancel);
1458
1459/**
1460 * __hrtimer_get_remaining - get remaining time for the timer
1461 * @timer:	the timer to read
1462 * @adjust:	adjust relative timers when CONFIG_TIME_LOW_RES=y
1463 */
1464ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust)
1465{
1466	unsigned long flags;
1467	ktime_t rem;
1468
1469	lock_hrtimer_base(timer, &flags);
1470	if (IS_ENABLED(CONFIG_TIME_LOW_RES) && adjust)
1471		rem = hrtimer_expires_remaining_adjusted(timer);
1472	else
1473		rem = hrtimer_expires_remaining(timer);
1474	unlock_hrtimer_base(timer, &flags);
1475
1476	return rem;
1477}
1478EXPORT_SYMBOL_GPL(__hrtimer_get_remaining);
1479
1480#ifdef CONFIG_NO_HZ_COMMON
1481/**
1482 * hrtimer_get_next_event - get the time until next expiry event
1483 *
1484 * Returns the next expiry time or KTIME_MAX if no timer is pending.
1485 */
1486u64 hrtimer_get_next_event(void)
1487{
1488	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1489	u64 expires = KTIME_MAX;
1490	unsigned long flags;
1491
1492	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1493
1494	if (!__hrtimer_hres_active(cpu_base))
1495		expires = __hrtimer_get_next_event(cpu_base, HRTIMER_ACTIVE_ALL);
1496
1497	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1498
1499	return expires;
1500}
1501
1502/**
1503 * hrtimer_next_event_without - time until next expiry event w/o one timer
1504 * @exclude:	timer to exclude
1505 *
1506 * Returns the next expiry time over all timers except for the @exclude one or
1507 * KTIME_MAX if none of them is pending.
1508 */
1509u64 hrtimer_next_event_without(const struct hrtimer *exclude)
1510{
1511	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1512	u64 expires = KTIME_MAX;
1513	unsigned long flags;
1514
1515	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1516
1517	if (__hrtimer_hres_active(cpu_base)) {
1518		unsigned int active;
1519
1520		if (!cpu_base->softirq_activated) {
1521			active = cpu_base->active_bases & HRTIMER_ACTIVE_SOFT;
1522			expires = __hrtimer_next_event_base(cpu_base, exclude,
1523							    active, KTIME_MAX);
1524		}
1525		active = cpu_base->active_bases & HRTIMER_ACTIVE_HARD;
1526		expires = __hrtimer_next_event_base(cpu_base, exclude, active,
1527						    expires);
1528	}
1529
1530	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1531
1532	return expires;
1533}
1534#endif
1535
1536static inline int hrtimer_clockid_to_base(clockid_t clock_id)
1537{
1538	if (likely(clock_id < MAX_CLOCKS)) {
1539		int base = hrtimer_clock_to_base_table[clock_id];
1540
1541		if (likely(base != HRTIMER_MAX_CLOCK_BASES))
1542			return base;
1543	}
1544	WARN(1, "Invalid clockid %d. Using MONOTONIC\n", clock_id);
1545	return HRTIMER_BASE_MONOTONIC;
1546}
1547
1548static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1549			   enum hrtimer_mode mode)
1550{
1551	bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
1552	struct hrtimer_cpu_base *cpu_base;
1553	int base;
1554
1555	/*
1556	 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1557	 * marked for hard interrupt expiry mode are moved into soft
1558	 * interrupt context for latency reasons and because the callbacks
1559	 * can invoke functions which might sleep on RT, e.g. spin_lock().
1560	 */
1561	if (IS_ENABLED(CONFIG_PREEMPT_RT) && !(mode & HRTIMER_MODE_HARD))
1562		softtimer = true;
1563
1564	memset(timer, 0, sizeof(struct hrtimer));
1565
1566	cpu_base = raw_cpu_ptr(&hrtimer_bases);
1567
1568	/*
1569	 * POSIX magic: Relative CLOCK_REALTIME timers are not affected by
1570	 * clock modifications, so they needs to become CLOCK_MONOTONIC to
1571	 * ensure POSIX compliance.
1572	 */
1573	if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
1574		clock_id = CLOCK_MONOTONIC;
1575
1576	base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
1577	base += hrtimer_clockid_to_base(clock_id);
1578	timer->is_soft = softtimer;
1579	timer->is_hard = !!(mode & HRTIMER_MODE_HARD);
1580	timer->base = &cpu_base->clock_base[base];
1581	timerqueue_init(&timer->node);
1582}
1583
1584/**
1585 * hrtimer_init - initialize a timer to the given clock
1586 * @timer:	the timer to be initialized
1587 * @clock_id:	the clock to be used
1588 * @mode:       The modes which are relevant for initialization:
1589 *              HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
1590 *              HRTIMER_MODE_REL_SOFT
1591 *
1592 *              The PINNED variants of the above can be handed in,
1593 *              but the PINNED bit is ignored as pinning happens
1594 *              when the hrtimer is started
1595 */
1596void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
1597		  enum hrtimer_mode mode)
1598{
1599	debug_init(timer, clock_id, mode);
1600	__hrtimer_init(timer, clock_id, mode);
1601}
1602EXPORT_SYMBOL_GPL(hrtimer_init);
1603
1604/*
1605 * A timer is active, when it is enqueued into the rbtree or the
1606 * callback function is running or it's in the state of being migrated
1607 * to another cpu.
1608 *
1609 * It is important for this function to not return a false negative.
1610 */
1611bool hrtimer_active(const struct hrtimer *timer)
1612{
1613	struct hrtimer_clock_base *base;
1614	unsigned int seq;
1615
1616	do {
1617		base = READ_ONCE(timer->base);
1618		seq = raw_read_seqcount_begin(&base->seq);
1619
1620		if (timer->state != HRTIMER_STATE_INACTIVE ||
1621		    base->running == timer)
1622			return true;
1623
1624	} while (read_seqcount_retry(&base->seq, seq) ||
1625		 base != READ_ONCE(timer->base));
1626
1627	return false;
1628}
1629EXPORT_SYMBOL_GPL(hrtimer_active);
1630
1631/*
1632 * The write_seqcount_barrier()s in __run_hrtimer() split the thing into 3
1633 * distinct sections:
1634 *
1635 *  - queued:	the timer is queued
1636 *  - callback:	the timer is being ran
1637 *  - post:	the timer is inactive or (re)queued
1638 *
1639 * On the read side we ensure we observe timer->state and cpu_base->running
1640 * from the same section, if anything changed while we looked at it, we retry.
1641 * This includes timer->base changing because sequence numbers alone are
1642 * insufficient for that.
1643 *
1644 * The sequence numbers are required because otherwise we could still observe
1645 * a false negative if the read side got smeared over multiple consecutive
1646 * __run_hrtimer() invocations.
1647 */
1648
1649static void __run_hrtimer(struct hrtimer_cpu_base *cpu_base,
1650			  struct hrtimer_clock_base *base,
1651			  struct hrtimer *timer, ktime_t *now,
1652			  unsigned long flags) __must_hold(&cpu_base->lock)
1653{
1654	enum hrtimer_restart (*fn)(struct hrtimer *);
1655	bool expires_in_hardirq;
1656	int restart;
1657
1658	lockdep_assert_held(&cpu_base->lock);
1659
1660	debug_deactivate(timer);
1661	base->running = timer;
1662
1663	/*
1664	 * Separate the ->running assignment from the ->state assignment.
1665	 *
1666	 * As with a regular write barrier, this ensures the read side in
1667	 * hrtimer_active() cannot observe base->running == NULL &&
1668	 * timer->state == INACTIVE.
1669	 */
1670	raw_write_seqcount_barrier(&base->seq);
1671
1672	__remove_hrtimer(timer, base, HRTIMER_STATE_INACTIVE, 0);
1673	fn = timer->function;
1674
1675	/*
1676	 * Clear the 'is relative' flag for the TIME_LOW_RES case. If the
1677	 * timer is restarted with a period then it becomes an absolute
1678	 * timer. If its not restarted it does not matter.
1679	 */
1680	if (IS_ENABLED(CONFIG_TIME_LOW_RES))
1681		timer->is_rel = false;
1682
1683	/*
1684	 * The timer is marked as running in the CPU base, so it is
1685	 * protected against migration to a different CPU even if the lock
1686	 * is dropped.
1687	 */
1688	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1689	trace_hrtimer_expire_entry(timer, now);
1690	expires_in_hardirq = lockdep_hrtimer_enter(timer);
1691
1692	restart = fn(timer);
1693
1694	lockdep_hrtimer_exit(expires_in_hardirq);
1695	trace_hrtimer_expire_exit(timer);
1696	raw_spin_lock_irq(&cpu_base->lock);
1697
1698	/*
1699	 * Note: We clear the running state after enqueue_hrtimer and
1700	 * we do not reprogram the event hardware. Happens either in
1701	 * hrtimer_start_range_ns() or in hrtimer_interrupt()
1702	 *
1703	 * Note: Because we dropped the cpu_base->lock above,
1704	 * hrtimer_start_range_ns() can have popped in and enqueued the timer
1705	 * for us already.
1706	 */
1707	if (restart != HRTIMER_NORESTART &&
1708	    !(timer->state & HRTIMER_STATE_ENQUEUED))
1709		enqueue_hrtimer(timer, base, HRTIMER_MODE_ABS);
1710
1711	/*
1712	 * Separate the ->running assignment from the ->state assignment.
1713	 *
1714	 * As with a regular write barrier, this ensures the read side in
1715	 * hrtimer_active() cannot observe base->running.timer == NULL &&
1716	 * timer->state == INACTIVE.
1717	 */
1718	raw_write_seqcount_barrier(&base->seq);
1719
1720	WARN_ON_ONCE(base->running != timer);
1721	base->running = NULL;
1722}
1723
1724static void __hrtimer_run_queues(struct hrtimer_cpu_base *cpu_base, ktime_t now,
1725				 unsigned long flags, unsigned int active_mask)
1726{
1727	struct hrtimer_clock_base *base;
1728	unsigned int active = cpu_base->active_bases & active_mask;
1729
1730	for_each_active_base(base, cpu_base, active) {
1731		struct timerqueue_node *node;
1732		ktime_t basenow;
1733
1734		basenow = ktime_add(now, base->offset);
1735
1736		while ((node = timerqueue_getnext(&base->active))) {
1737			struct hrtimer *timer;
1738
1739			timer = container_of(node, struct hrtimer, node);
1740
1741			/*
1742			 * The immediate goal for using the softexpires is
1743			 * minimizing wakeups, not running timers at the
1744			 * earliest interrupt after their soft expiration.
1745			 * This allows us to avoid using a Priority Search
1746			 * Tree, which can answer a stabbing query for
1747			 * overlapping intervals and instead use the simple
1748			 * BST we already have.
1749			 * We don't add extra wakeups by delaying timers that
1750			 * are right-of a not yet expired timer, because that
1751			 * timer will have to trigger a wakeup anyway.
1752			 */
1753			if (basenow < hrtimer_get_softexpires_tv64(timer))
1754				break;
1755
1756			__run_hrtimer(cpu_base, base, timer, &basenow, flags);
1757			if (active_mask == HRTIMER_ACTIVE_SOFT)
1758				hrtimer_sync_wait_running(cpu_base, flags);
1759		}
1760	}
1761}
1762
1763static __latent_entropy void hrtimer_run_softirq(struct softirq_action *h)
1764{
1765	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1766	unsigned long flags;
1767	ktime_t now;
1768
1769	hrtimer_cpu_base_lock_expiry(cpu_base);
1770	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1771
1772	now = hrtimer_update_base(cpu_base);
1773	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_SOFT);
1774
1775	cpu_base->softirq_activated = 0;
1776	hrtimer_update_softirq_timer(cpu_base, true);
1777
1778	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1779	hrtimer_cpu_base_unlock_expiry(cpu_base);
1780}
1781
1782#ifdef CONFIG_HIGH_RES_TIMERS
1783
1784/*
1785 * High resolution timer interrupt
1786 * Called with interrupts disabled
1787 */
1788void hrtimer_interrupt(struct clock_event_device *dev)
1789{
1790	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1791	ktime_t expires_next, now, entry_time, delta;
1792	unsigned long flags;
1793	int retries = 0;
1794
1795	BUG_ON(!cpu_base->hres_active);
1796	cpu_base->nr_events++;
1797	dev->next_event = KTIME_MAX;
1798
1799	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1800	entry_time = now = hrtimer_update_base(cpu_base);
1801retry:
1802	cpu_base->in_hrtirq = 1;
1803	/*
1804	 * We set expires_next to KTIME_MAX here with cpu_base->lock
1805	 * held to prevent that a timer is enqueued in our queue via
1806	 * the migration code. This does not affect enqueueing of
1807	 * timers which run their callback and need to be requeued on
1808	 * this CPU.
1809	 */
1810	cpu_base->expires_next = KTIME_MAX;
1811
1812	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1813		cpu_base->softirq_expires_next = KTIME_MAX;
1814		cpu_base->softirq_activated = 1;
1815		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1816	}
1817
1818	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1819
1820	/* Reevaluate the clock bases for the [soft] next expiry */
1821	expires_next = hrtimer_update_next_event(cpu_base);
1822	/*
1823	 * Store the new expiry value so the migration code can verify
1824	 * against it.
1825	 */
1826	cpu_base->expires_next = expires_next;
1827	cpu_base->in_hrtirq = 0;
1828	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1829
1830	/* Reprogramming necessary ? */
1831	if (!tick_program_event(expires_next, 0)) {
1832		cpu_base->hang_detected = 0;
1833		return;
1834	}
1835
1836	/*
1837	 * The next timer was already expired due to:
1838	 * - tracing
1839	 * - long lasting callbacks
1840	 * - being scheduled away when running in a VM
1841	 *
1842	 * We need to prevent that we loop forever in the hrtimer
1843	 * interrupt routine. We give it 3 attempts to avoid
1844	 * overreacting on some spurious event.
1845	 *
1846	 * Acquire base lock for updating the offsets and retrieving
1847	 * the current time.
1848	 */
1849	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1850	now = hrtimer_update_base(cpu_base);
1851	cpu_base->nr_retries++;
1852	if (++retries < 3)
1853		goto retry;
1854	/*
1855	 * Give the system a chance to do something else than looping
1856	 * here. We stored the entry time, so we know exactly how long
1857	 * we spent here. We schedule the next event this amount of
1858	 * time away.
1859	 */
1860	cpu_base->nr_hangs++;
1861	cpu_base->hang_detected = 1;
1862	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1863
1864	delta = ktime_sub(now, entry_time);
1865	if ((unsigned int)delta > cpu_base->max_hang_time)
1866		cpu_base->max_hang_time = (unsigned int) delta;
1867	/*
1868	 * Limit it to a sensible value as we enforce a longer
1869	 * delay. Give the CPU at least 100ms to catch up.
1870	 */
1871	if (delta > 100 * NSEC_PER_MSEC)
1872		expires_next = ktime_add_ns(now, 100 * NSEC_PER_MSEC);
1873	else
1874		expires_next = ktime_add(now, delta);
1875	tick_program_event(expires_next, 1);
1876	pr_warn_once("hrtimer: interrupt took %llu ns\n", ktime_to_ns(delta));
1877}
1878
1879/* called with interrupts disabled */
1880static inline void __hrtimer_peek_ahead_timers(void)
1881{
1882	struct tick_device *td;
1883
1884	if (!hrtimer_hres_active())
1885		return;
1886
1887	td = this_cpu_ptr(&tick_cpu_device);
1888	if (td && td->evtdev)
1889		hrtimer_interrupt(td->evtdev);
1890}
1891
1892#else /* CONFIG_HIGH_RES_TIMERS */
1893
1894static inline void __hrtimer_peek_ahead_timers(void) { }
1895
1896#endif	/* !CONFIG_HIGH_RES_TIMERS */
1897
1898/*
1899 * Called from run_local_timers in hardirq context every jiffy
1900 */
1901void hrtimer_run_queues(void)
1902{
1903	struct hrtimer_cpu_base *cpu_base = this_cpu_ptr(&hrtimer_bases);
1904	unsigned long flags;
1905	ktime_t now;
1906
1907	if (__hrtimer_hres_active(cpu_base))
1908		return;
1909
1910	/*
1911	 * This _is_ ugly: We have to check periodically, whether we
1912	 * can switch to highres and / or nohz mode. The clocksource
1913	 * switch happens with xtime_lock held. Notification from
1914	 * there only sets the check bit in the tick_oneshot code,
1915	 * otherwise we might deadlock vs. xtime_lock.
1916	 */
1917	if (tick_check_oneshot_change(!hrtimer_is_hres_enabled())) {
1918		hrtimer_switch_to_hres();
1919		return;
1920	}
1921
1922	raw_spin_lock_irqsave(&cpu_base->lock, flags);
1923	now = hrtimer_update_base(cpu_base);
1924
1925	if (!ktime_before(now, cpu_base->softirq_expires_next)) {
1926		cpu_base->softirq_expires_next = KTIME_MAX;
1927		cpu_base->softirq_activated = 1;
1928		raise_softirq_irqoff(HRTIMER_SOFTIRQ);
1929	}
1930
1931	__hrtimer_run_queues(cpu_base, now, flags, HRTIMER_ACTIVE_HARD);
1932	raw_spin_unlock_irqrestore(&cpu_base->lock, flags);
1933}
1934
1935/*
1936 * Sleep related functions:
1937 */
1938static enum hrtimer_restart hrtimer_wakeup(struct hrtimer *timer)
1939{
1940	struct hrtimer_sleeper *t =
1941		container_of(timer, struct hrtimer_sleeper, timer);
1942	struct task_struct *task = t->task;
1943
1944	t->task = NULL;
1945	if (task)
1946		wake_up_process(task);
1947
1948	return HRTIMER_NORESTART;
1949}
1950
1951/**
1952 * hrtimer_sleeper_start_expires - Start a hrtimer sleeper timer
1953 * @sl:		sleeper to be started
1954 * @mode:	timer mode abs/rel
1955 *
1956 * Wrapper around hrtimer_start_expires() for hrtimer_sleeper based timers
1957 * to allow PREEMPT_RT to tweak the delivery mode (soft/hardirq context)
1958 */
1959void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
1960				   enum hrtimer_mode mode)
1961{
1962	/*
1963	 * Make the enqueue delivery mode check work on RT. If the sleeper
1964	 * was initialized for hard interrupt delivery, force the mode bit.
1965	 * This is a special case for hrtimer_sleepers because
1966	 * hrtimer_init_sleeper() determines the delivery mode on RT so the
1967	 * fiddling with this decision is avoided at the call sites.
1968	 */
1969	if (IS_ENABLED(CONFIG_PREEMPT_RT) && sl->timer.is_hard)
1970		mode |= HRTIMER_MODE_HARD;
1971
1972	hrtimer_start_expires(&sl->timer, mode);
1973}
1974EXPORT_SYMBOL_GPL(hrtimer_sleeper_start_expires);
1975
1976static void __hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
1977				   clockid_t clock_id, enum hrtimer_mode mode)
1978{
1979	/*
1980	 * On PREEMPT_RT enabled kernels hrtimers which are not explicitly
1981	 * marked for hard interrupt expiry mode are moved into soft
1982	 * interrupt context either for latency reasons or because the
1983	 * hrtimer callback takes regular spinlocks or invokes other
1984	 * functions which are not suitable for hard interrupt context on
1985	 * PREEMPT_RT.
1986	 *
1987	 * The hrtimer_sleeper callback is RT compatible in hard interrupt
1988	 * context, but there is a latency concern: Untrusted userspace can
1989	 * spawn many threads which arm timers for the same expiry time on
1990	 * the same CPU. That causes a latency spike due to the wakeup of
1991	 * a gazillion threads.
1992	 *
1993	 * OTOH, privileged real-time user space applications rely on the
1994	 * low latency of hard interrupt wakeups. If the current task is in
1995	 * a real-time scheduling class, mark the mode for hard interrupt
1996	 * expiry.
1997	 */
1998	if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
1999		if (task_is_realtime(current) && !(mode & HRTIMER_MODE_SOFT))
2000			mode |= HRTIMER_MODE_HARD;
2001	}
2002
2003	__hrtimer_init(&sl->timer, clock_id, mode);
2004	sl->timer.function = hrtimer_wakeup;
2005	sl->task = current;
2006}
2007
2008/**
2009 * hrtimer_init_sleeper - initialize sleeper to the given clock
2010 * @sl:		sleeper to be initialized
2011 * @clock_id:	the clock to be used
2012 * @mode:	timer mode abs/rel
2013 */
2014void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
2015			  enum hrtimer_mode mode)
2016{
2017	debug_init(&sl->timer, clock_id, mode);
2018	__hrtimer_init_sleeper(sl, clock_id, mode);
2019
2020}
2021EXPORT_SYMBOL_GPL(hrtimer_init_sleeper);
2022
2023int nanosleep_copyout(struct restart_block *restart, struct timespec64 *ts)
2024{
2025	switch(restart->nanosleep.type) {
2026#ifdef CONFIG_COMPAT_32BIT_TIME
2027	case TT_COMPAT:
2028		if (put_old_timespec32(ts, restart->nanosleep.compat_rmtp))
2029			return -EFAULT;
2030		break;
2031#endif
2032	case TT_NATIVE:
2033		if (put_timespec64(ts, restart->nanosleep.rmtp))
2034			return -EFAULT;
2035		break;
2036	default:
2037		BUG();
2038	}
2039	return -ERESTART_RESTARTBLOCK;
2040}
2041
2042static int __sched do_nanosleep(struct hrtimer_sleeper *t, enum hrtimer_mode mode)
2043{
2044	struct restart_block *restart;
2045
2046	do {
2047		set_current_state(TASK_INTERRUPTIBLE|TASK_FREEZABLE);
2048		hrtimer_sleeper_start_expires(t, mode);
2049
2050		if (likely(t->task))
2051			schedule();
2052
2053		hrtimer_cancel(&t->timer);
2054		mode = HRTIMER_MODE_ABS;
2055
2056	} while (t->task && !signal_pending(current));
2057
2058	__set_current_state(TASK_RUNNING);
2059
2060	if (!t->task)
2061		return 0;
2062
2063	restart = &current->restart_block;
2064	if (restart->nanosleep.type != TT_NONE) {
2065		ktime_t rem = hrtimer_expires_remaining(&t->timer);
2066		struct timespec64 rmt;
2067
2068		if (rem <= 0)
2069			return 0;
2070		rmt = ktime_to_timespec64(rem);
2071
2072		return nanosleep_copyout(restart, &rmt);
2073	}
2074	return -ERESTART_RESTARTBLOCK;
2075}
2076
2077static long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
2078{
2079	struct hrtimer_sleeper t;
2080	int ret;
2081
2082	hrtimer_init_sleeper_on_stack(&t, restart->nanosleep.clockid,
2083				      HRTIMER_MODE_ABS);
2084	hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
2085	ret = do_nanosleep(&t, HRTIMER_MODE_ABS);
2086	destroy_hrtimer_on_stack(&t.timer);
2087	return ret;
2088}
2089
2090long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
2091		       const clockid_t clockid)
2092{
2093	struct restart_block *restart;
2094	struct hrtimer_sleeper t;
2095	int ret = 0;
2096	u64 slack;
2097
2098	slack = current->timer_slack_ns;
2099	if (rt_task(current))
2100		slack = 0;
2101
2102	hrtimer_init_sleeper_on_stack(&t, clockid, mode);
2103	hrtimer_set_expires_range_ns(&t.timer, rqtp, slack);
2104	ret = do_nanosleep(&t, mode);
2105	if (ret != -ERESTART_RESTARTBLOCK)
2106		goto out;
2107
2108	/* Absolute timers do not update the rmtp value and restart: */
2109	if (mode == HRTIMER_MODE_ABS) {
2110		ret = -ERESTARTNOHAND;
2111		goto out;
2112	}
2113
2114	restart = &current->restart_block;
 
2115	restart->nanosleep.clockid = t.timer.base->clockid;
2116	restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
2117	set_restart_fn(restart, hrtimer_nanosleep_restart);
2118out:
2119	destroy_hrtimer_on_stack(&t.timer);
2120	return ret;
2121}
2122
2123#ifdef CONFIG_64BIT
2124
2125SYSCALL_DEFINE2(nanosleep, struct __kernel_timespec __user *, rqtp,
2126		struct __kernel_timespec __user *, rmtp)
2127{
2128	struct timespec64 tu;
2129
2130	if (get_timespec64(&tu, rqtp))
2131		return -EFAULT;
2132
2133	if (!timespec64_valid(&tu))
2134		return -EINVAL;
2135
2136	current->restart_block.fn = do_no_restart_syscall;
2137	current->restart_block.nanosleep.type = rmtp ? TT_NATIVE : TT_NONE;
2138	current->restart_block.nanosleep.rmtp = rmtp;
2139	return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2140				 CLOCK_MONOTONIC);
2141}
2142
2143#endif
2144
2145#ifdef CONFIG_COMPAT_32BIT_TIME
2146
2147SYSCALL_DEFINE2(nanosleep_time32, struct old_timespec32 __user *, rqtp,
2148		       struct old_timespec32 __user *, rmtp)
2149{
2150	struct timespec64 tu;
2151
2152	if (get_old_timespec32(&tu, rqtp))
2153		return -EFAULT;
2154
2155	if (!timespec64_valid(&tu))
2156		return -EINVAL;
2157
2158	current->restart_block.fn = do_no_restart_syscall;
2159	current->restart_block.nanosleep.type = rmtp ? TT_COMPAT : TT_NONE;
2160	current->restart_block.nanosleep.compat_rmtp = rmtp;
2161	return hrtimer_nanosleep(timespec64_to_ktime(tu), HRTIMER_MODE_REL,
2162				 CLOCK_MONOTONIC);
2163}
2164#endif
2165
2166/*
2167 * Functions related to boot-time initialization:
2168 */
2169int hrtimers_prepare_cpu(unsigned int cpu)
2170{
2171	struct hrtimer_cpu_base *cpu_base = &per_cpu(hrtimer_bases, cpu);
2172	int i;
2173
2174	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2175		struct hrtimer_clock_base *clock_b = &cpu_base->clock_base[i];
2176
2177		clock_b->cpu_base = cpu_base;
2178		seqcount_raw_spinlock_init(&clock_b->seq, &cpu_base->lock);
2179		timerqueue_init_head(&clock_b->active);
2180	}
2181
2182	cpu_base->cpu = cpu;
2183	cpu_base->active_bases = 0;
2184	cpu_base->hres_active = 0;
2185	cpu_base->hang_detected = 0;
2186	cpu_base->next_timer = NULL;
2187	cpu_base->softirq_next_timer = NULL;
2188	cpu_base->expires_next = KTIME_MAX;
2189	cpu_base->softirq_expires_next = KTIME_MAX;
2190	cpu_base->online = 1;
2191	hrtimer_cpu_base_init_expiry_lock(cpu_base);
2192	return 0;
2193}
2194
2195#ifdef CONFIG_HOTPLUG_CPU
2196
2197static void migrate_hrtimer_list(struct hrtimer_clock_base *old_base,
2198				struct hrtimer_clock_base *new_base)
2199{
2200	struct hrtimer *timer;
2201	struct timerqueue_node *node;
2202
2203	while ((node = timerqueue_getnext(&old_base->active))) {
2204		timer = container_of(node, struct hrtimer, node);
2205		BUG_ON(hrtimer_callback_running(timer));
2206		debug_deactivate(timer);
2207
2208		/*
2209		 * Mark it as ENQUEUED not INACTIVE otherwise the
2210		 * timer could be seen as !active and just vanish away
2211		 * under us on another CPU
2212		 */
2213		__remove_hrtimer(timer, old_base, HRTIMER_STATE_ENQUEUED, 0);
2214		timer->base = new_base;
2215		/*
2216		 * Enqueue the timers on the new cpu. This does not
2217		 * reprogram the event device in case the timer
2218		 * expires before the earliest on this CPU, but we run
2219		 * hrtimer_interrupt after we migrated everything to
2220		 * sort out already expired timers and reprogram the
2221		 * event device.
2222		 */
2223		enqueue_hrtimer(timer, new_base, HRTIMER_MODE_ABS);
2224	}
2225}
2226
2227int hrtimers_cpu_dying(unsigned int dying_cpu)
2228{
2229	int i, ncpu = cpumask_any_and(cpu_active_mask, housekeeping_cpumask(HK_TYPE_TIMER));
2230	struct hrtimer_cpu_base *old_base, *new_base;
 
2231
2232	old_base = this_cpu_ptr(&hrtimer_bases);
2233	new_base = &per_cpu(hrtimer_bases, ncpu);
2234
2235	/*
 
 
 
 
 
 
 
 
 
2236	 * The caller is globally serialized and nobody else
2237	 * takes two locks at once, deadlock is not possible.
2238	 */
2239	raw_spin_lock(&old_base->lock);
2240	raw_spin_lock_nested(&new_base->lock, SINGLE_DEPTH_NESTING);
2241
2242	for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
2243		migrate_hrtimer_list(&old_base->clock_base[i],
2244				     &new_base->clock_base[i]);
2245	}
2246
2247	/*
2248	 * The migration might have changed the first expiring softirq
2249	 * timer on this CPU. Update it.
2250	 */
2251	__hrtimer_get_next_event(new_base, HRTIMER_ACTIVE_SOFT);
2252	/* Tell the other CPU to retrigger the next event */
2253	smp_call_function_single(ncpu, retrigger_next_event, NULL, 0);
2254
2255	raw_spin_unlock(&new_base->lock);
2256	old_base->online = 0;
2257	raw_spin_unlock(&old_base->lock);
 
2258
 
 
 
 
2259	return 0;
2260}
2261
2262#endif /* CONFIG_HOTPLUG_CPU */
2263
2264void __init hrtimers_init(void)
2265{
2266	hrtimers_prepare_cpu(smp_processor_id());
2267	open_softirq(HRTIMER_SOFTIRQ, hrtimer_run_softirq);
2268}
2269
2270/**
2271 * schedule_hrtimeout_range_clock - sleep until timeout
2272 * @expires:	timeout value (ktime_t)
2273 * @delta:	slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2274 * @mode:	timer mode
2275 * @clock_id:	timer clock to be used
2276 */
2277int __sched
2278schedule_hrtimeout_range_clock(ktime_t *expires, u64 delta,
2279			       const enum hrtimer_mode mode, clockid_t clock_id)
2280{
2281	struct hrtimer_sleeper t;
2282
2283	/*
2284	 * Optimize when a zero timeout value is given. It does not
2285	 * matter whether this is an absolute or a relative time.
2286	 */
2287	if (expires && *expires == 0) {
2288		__set_current_state(TASK_RUNNING);
2289		return 0;
2290	}
2291
2292	/*
2293	 * A NULL parameter means "infinite"
2294	 */
2295	if (!expires) {
2296		schedule();
2297		return -EINTR;
2298	}
2299
2300	/*
2301	 * Override any slack passed by the user if under
2302	 * rt contraints.
2303	 */
2304	if (rt_task(current))
2305		delta = 0;
2306
2307	hrtimer_init_sleeper_on_stack(&t, clock_id, mode);
2308	hrtimer_set_expires_range_ns(&t.timer, *expires, delta);
2309	hrtimer_sleeper_start_expires(&t, mode);
2310
2311	if (likely(t.task))
2312		schedule();
2313
2314	hrtimer_cancel(&t.timer);
2315	destroy_hrtimer_on_stack(&t.timer);
2316
2317	__set_current_state(TASK_RUNNING);
2318
2319	return !t.task ? 0 : -EINTR;
2320}
2321EXPORT_SYMBOL_GPL(schedule_hrtimeout_range_clock);
2322
2323/**
2324 * schedule_hrtimeout_range - sleep until timeout
2325 * @expires:	timeout value (ktime_t)
2326 * @delta:	slack in expires timeout (ktime_t) for SCHED_OTHER tasks
2327 * @mode:	timer mode
2328 *
2329 * Make the current task sleep until the given expiry time has
2330 * elapsed. The routine will return immediately unless
2331 * the current task state has been set (see set_current_state()).
2332 *
2333 * The @delta argument gives the kernel the freedom to schedule the
2334 * actual wakeup to a time that is both power and performance friendly
2335 * for regular (non RT/DL) tasks.
2336 * The kernel give the normal best effort behavior for "@expires+@delta",
2337 * but may decide to fire the timer earlier, but no earlier than @expires.
2338 *
2339 * You can set the task state as follows -
2340 *
2341 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2342 * pass before the routine returns unless the current task is explicitly
2343 * woken up, (e.g. by wake_up_process()).
2344 *
2345 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2346 * delivered to the current task or the current task is explicitly woken
2347 * up.
2348 *
2349 * The current task state is guaranteed to be TASK_RUNNING when this
2350 * routine returns.
2351 *
2352 * Returns 0 when the timer has expired. If the task was woken before the
2353 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2354 * by an explicit wakeup, it returns -EINTR.
2355 */
2356int __sched schedule_hrtimeout_range(ktime_t *expires, u64 delta,
2357				     const enum hrtimer_mode mode)
2358{
2359	return schedule_hrtimeout_range_clock(expires, delta, mode,
2360					      CLOCK_MONOTONIC);
2361}
2362EXPORT_SYMBOL_GPL(schedule_hrtimeout_range);
2363
2364/**
2365 * schedule_hrtimeout - sleep until timeout
2366 * @expires:	timeout value (ktime_t)
2367 * @mode:	timer mode
2368 *
2369 * Make the current task sleep until the given expiry time has
2370 * elapsed. The routine will return immediately unless
2371 * the current task state has been set (see set_current_state()).
2372 *
2373 * You can set the task state as follows -
2374 *
2375 * %TASK_UNINTERRUPTIBLE - at least @timeout time is guaranteed to
2376 * pass before the routine returns unless the current task is explicitly
2377 * woken up, (e.g. by wake_up_process()).
2378 *
2379 * %TASK_INTERRUPTIBLE - the routine may return early if a signal is
2380 * delivered to the current task or the current task is explicitly woken
2381 * up.
2382 *
2383 * The current task state is guaranteed to be TASK_RUNNING when this
2384 * routine returns.
2385 *
2386 * Returns 0 when the timer has expired. If the task was woken before the
2387 * timer expired by a signal (only possible in state TASK_INTERRUPTIBLE) or
2388 * by an explicit wakeup, it returns -EINTR.
2389 */
2390int __sched schedule_hrtimeout(ktime_t *expires,
2391			       const enum hrtimer_mode mode)
2392{
2393	return schedule_hrtimeout_range(expires, 0, mode);
2394}
2395EXPORT_SYMBOL_GPL(schedule_hrtimeout);