root/include/linux/hrtimer.h

INCLUDED FROM

DEFINITIONS

1. hrtimer_set_expires
2. hrtimer_set_expires_range
3. hrtimer_set_expires_range_ns
4. hrtimer_set_expires_tv64
5. hrtimer_add_expires
6. hrtimer_add_expires_ns
7. hrtimer_get_expires
8. hrtimer_get_softexpires
9. hrtimer_get_expires_tv64
10. hrtimer_get_softexpires_tv64
11. hrtimer_get_expires_ns
12. hrtimer_expires_remaining
13. hrtimer_cb_get_time
14. hrtimer_is_hres_active
15. clock_was_set_delayed
16. __hrtimer_expires_remaining_adjusted
17. hrtimer_expires_remaining_adjusted
18. timerfd_clock_was_set
19. hrtimer_cancel_wait_running
20. hrtimer_init_on_stack
21. hrtimer_init_sleeper_on_stack
22. destroy_hrtimer_on_stack
23. hrtimer_start
24. hrtimer_start_expires
25. hrtimer_restart
26. hrtimer_get_remaining
27. hrtimer_is_queued
28. hrtimer_callback_running
29. hrtimer_forward_now

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  hrtimers - High-resolution kernel timers
   4  *
   5  *   Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
   6  *   Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
   7  *
   8  *  data type definitions, declarations, prototypes
   9  *
  10  *  Started by: Thomas Gleixner and Ingo Molnar
  11  */
  12 #ifndef _LINUX_HRTIMER_H
  13 #define _LINUX_HRTIMER_H
  14 
  15 #include <linux/hrtimer_defs.h>
  16 #include <linux/rbtree.h>
  17 #include <linux/init.h>
  18 #include <linux/list.h>
  19 #include <linux/percpu.h>
  20 #include <linux/timer.h>
  21 #include <linux/timerqueue.h>
  22 
  23 struct hrtimer_clock_base;
  24 struct hrtimer_cpu_base;
  25 
  26 /*
  27  * Mode arguments of xxx_hrtimer functions:
  28  *
  29  * HRTIMER_MODE_ABS             - Time value is absolute
  30  * HRTIMER_MODE_REL             - Time value is relative to now
  31  * HRTIMER_MODE_PINNED          - Timer is bound to CPU (is only considered
  32  *                                when starting the timer)
  33  * HRTIMER_MODE_SOFT            - Timer callback function will be executed in
  34  *                                soft irq context
  35  * HRTIMER_MODE_HARD            - Timer callback function will be executed in
  36  *                                hard irq context even on PREEMPT_RT.
  37  */
  38 enum hrtimer_mode {
  39         HRTIMER_MODE_ABS        = 0x00,
  40         HRTIMER_MODE_REL        = 0x01,
  41         HRTIMER_MODE_PINNED     = 0x02,
  42         HRTIMER_MODE_SOFT       = 0x04,
  43         HRTIMER_MODE_HARD       = 0x08,
  44 
  45         HRTIMER_MODE_ABS_PINNED = HRTIMER_MODE_ABS | HRTIMER_MODE_PINNED,
  46         HRTIMER_MODE_REL_PINNED = HRTIMER_MODE_REL | HRTIMER_MODE_PINNED,
  47 
  48         HRTIMER_MODE_ABS_SOFT   = HRTIMER_MODE_ABS | HRTIMER_MODE_SOFT,
  49         HRTIMER_MODE_REL_SOFT   = HRTIMER_MODE_REL | HRTIMER_MODE_SOFT,
  50 
  51         HRTIMER_MODE_ABS_PINNED_SOFT = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_SOFT,
  52         HRTIMER_MODE_REL_PINNED_SOFT = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_SOFT,
  53 
  54         HRTIMER_MODE_ABS_HARD   = HRTIMER_MODE_ABS | HRTIMER_MODE_HARD,
  55         HRTIMER_MODE_REL_HARD   = HRTIMER_MODE_REL | HRTIMER_MODE_HARD,
  56 
  57         HRTIMER_MODE_ABS_PINNED_HARD = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_HARD,
  58         HRTIMER_MODE_REL_PINNED_HARD = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_HARD,
  59 };
  60 
  61 /*
  62  * Return values for the callback function
  63  */
  64 enum hrtimer_restart {
  65         HRTIMER_NORESTART,      /* Timer is not restarted */
  66         HRTIMER_RESTART,        /* Timer must be restarted */
  67 };
  68 
  69 /*
  70  * Values to track state of the timer
  71  *
  72  * Possible states:
  73  *
  74  * 0x00         inactive
  75  * 0x01         enqueued into rbtree
  76  *
  77  * The callback state is not part of the timer->state because clearing it would
  78  * mean touching the timer after the callback, this makes it impossible to free
  79  * the timer from the callback function.
  80  *
  81  * Therefore we track the callback state in:
  82  *
  83  *      timer->base->cpu_base->running == timer
  84  *
  85  * On SMP it is possible to have a "callback function running and enqueued"
  86  * status. It happens for example when a posix timer expired and the callback
  87  * queued a signal. Between dropping the lock which protects the posix timer
  88  * and reacquiring the base lock of the hrtimer, another CPU can deliver the
  89  * signal and rearm the timer.
  90  *
  91  * All state transitions are protected by cpu_base->lock.
  92  */
  93 #define HRTIMER_STATE_INACTIVE  0x00
  94 #define HRTIMER_STATE_ENQUEUED  0x01
  95 
  96 /**
  97  * struct hrtimer - the basic hrtimer structure
  98  * @node:       timerqueue node, which also manages node.expires,
  99  *              the absolute expiry time in the hrtimers internal
 100  *              representation. The time is related to the clock on
 101  *              which the timer is based. Is setup by adding
 102  *              slack to the _softexpires value. For non range timers
 103  *              identical to _softexpires.
 104  * @_softexpires: the absolute earliest expiry time of the hrtimer.
 105  *              The time which was given as expiry time when the timer
 106  *              was armed.
 107  * @function:   timer expiry callback function
 108  * @base:       pointer to the timer base (per cpu and per clock)
 109  * @state:      state information (See bit values above)
 110  * @is_rel:     Set if the timer was armed relative
 111  * @is_soft:    Set if hrtimer will be expired in soft interrupt context.
 112  * @is_hard:    Set if hrtimer will be expired in hard interrupt context
 113  *              even on RT.
 114  *
 115  * The hrtimer structure must be initialized by hrtimer_init()
 116  */
 117 struct hrtimer {
 118         struct timerqueue_node          node;
 119         ktime_t                         _softexpires;
 120         enum hrtimer_restart            (*function)(struct hrtimer *);
 121         struct hrtimer_clock_base       *base;
 122         u8                              state;
 123         u8                              is_rel;
 124         u8                              is_soft;
 125         u8                              is_hard;
 126 };
 127 
 128 /**
 129  * struct hrtimer_sleeper - simple sleeper structure
 130  * @timer:      embedded timer structure
 131  * @task:       task to wake up
 132  *
 133  * task is set to NULL, when the timer expires.
 134  */
 135 struct hrtimer_sleeper {
 136         struct hrtimer timer;
 137         struct task_struct *task;
 138 };
 139 
 140 #ifdef CONFIG_64BIT
 141 # define __hrtimer_clock_base_align     ____cacheline_aligned
 142 #else
 143 # define __hrtimer_clock_base_align
 144 #endif
 145 
 146 /**
 147  * struct hrtimer_clock_base - the timer base for a specific clock
 148  * @cpu_base:           per cpu clock base
 149  * @index:              clock type index for per_cpu support when moving a
 150  *                      timer to a base on another cpu.
 151  * @clockid:            clock id for per_cpu support
 152  * @seq:                seqcount around __run_hrtimer
 153  * @running:            pointer to the currently running hrtimer
 154  * @active:             red black tree root node for the active timers
 155  * @get_time:           function to retrieve the current time of the clock
 156  * @offset:             offset of this clock to the monotonic base
 157  */
 158 struct hrtimer_clock_base {
 159         struct hrtimer_cpu_base *cpu_base;
 160         unsigned int            index;
 161         clockid_t               clockid;
 162         seqcount_t              seq;
 163         struct hrtimer          *running;
 164         struct timerqueue_head  active;
 165         ktime_t                 (*get_time)(void);
 166         ktime_t                 offset;
 167 } __hrtimer_clock_base_align;
 168 
 169 enum  hrtimer_base_type {
 170         HRTIMER_BASE_MONOTONIC,
 171         HRTIMER_BASE_REALTIME,
 172         HRTIMER_BASE_BOOTTIME,
 173         HRTIMER_BASE_TAI,
 174         HRTIMER_BASE_MONOTONIC_SOFT,
 175         HRTIMER_BASE_REALTIME_SOFT,
 176         HRTIMER_BASE_BOOTTIME_SOFT,
 177         HRTIMER_BASE_TAI_SOFT,
 178         HRTIMER_MAX_CLOCK_BASES,
 179 };
 180 
 181 /**
 182  * struct hrtimer_cpu_base - the per cpu clock bases
 183  * @lock:               lock protecting the base and associated clock bases
 184  *                      and timers
 185  * @cpu:                cpu number
 186  * @active_bases:       Bitfield to mark bases with active timers
 187  * @clock_was_set_seq:  Sequence counter of clock was set events
 188  * @hres_active:        State of high resolution mode
 189  * @in_hrtirq:          hrtimer_interrupt() is currently executing
 190  * @hang_detected:      The last hrtimer interrupt detected a hang
 191  * @softirq_activated:  displays, if the softirq is raised - update of softirq
 192  *                      related settings is not required then.
 193  * @nr_events:          Total number of hrtimer interrupt events
 194  * @nr_retries:         Total number of hrtimer interrupt retries
 195  * @nr_hangs:           Total number of hrtimer interrupt hangs
 196  * @max_hang_time:      Maximum time spent in hrtimer_interrupt
 197  * @softirq_expiry_lock: Lock which is taken while softirq based hrtimer are
 198  *                       expired
 199  * @timer_waiters:      A hrtimer_cancel() invocation waits for the timer
 200  *                      callback to finish.
 201  * @expires_next:       absolute time of the next event, is required for remote
 202  *                      hrtimer enqueue; it is the total first expiry time (hard
 203  *                      and soft hrtimer are taken into account)
 204  * @next_timer:         Pointer to the first expiring timer
 205  * @softirq_expires_next: Time to check, if soft queues needs also to be expired
 206  * @softirq_next_timer: Pointer to the first expiring softirq based timer
 207  * @clock_base:         array of clock bases for this cpu
 208  *
 209  * Note: next_timer is just an optimization for __remove_hrtimer().
 210  *       Do not dereference the pointer because it is not reliable on
 211  *       cross cpu removals.
 212  */
 213 struct hrtimer_cpu_base {
 214         raw_spinlock_t                  lock;
 215         unsigned int                    cpu;
 216         unsigned int                    active_bases;
 217         unsigned int                    clock_was_set_seq;
 218         unsigned int                    hres_active             : 1,
 219                                         in_hrtirq               : 1,
 220                                         hang_detected           : 1,
 221                                         softirq_activated       : 1;
 222 #ifdef CONFIG_HIGH_RES_TIMERS
 223         unsigned int                    nr_events;
 224         unsigned short                  nr_retries;
 225         unsigned short                  nr_hangs;
 226         unsigned int                    max_hang_time;
 227 #endif
 228 #ifdef CONFIG_PREEMPT_RT
 229         spinlock_t                      softirq_expiry_lock;
 230         atomic_t                        timer_waiters;
 231 #endif
 232         ktime_t                         expires_next;
 233         struct hrtimer                  *next_timer;
 234         ktime_t                         softirq_expires_next;
 235         struct hrtimer                  *softirq_next_timer;
 236         struct hrtimer_clock_base       clock_base[HRTIMER_MAX_CLOCK_BASES];
 237 } ____cacheline_aligned;
 238 
 239 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
 240 {
 241         timer->node.expires = time;
 242         timer->_softexpires = time;
 243 }
 244 
 245 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
 246 {
 247         timer->_softexpires = time;
 248         timer->node.expires = ktime_add_safe(time, delta);
 249 }
 250 
 251 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, u64 delta)
 252 {
 253         timer->_softexpires = time;
 254         timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
 255 }
 256 
 257 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
 258 {
 259         timer->node.expires = tv64;
 260         timer->_softexpires = tv64;
 261 }
 262 
 263 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
 264 {
 265         timer->node.expires = ktime_add_safe(timer->node.expires, time);
 266         timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
 267 }
 268 
 269 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
 270 {
 271         timer->node.expires = ktime_add_ns(timer->node.expires, ns);
 272         timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
 273 }
 274 
 275 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
 276 {
 277         return timer->node.expires;
 278 }
 279 
 280 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
 281 {
 282         return timer->_softexpires;
 283 }
 284 
 285 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
 286 {
 287         return timer->node.expires;
 288 }
 289 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
 290 {
 291         return timer->_softexpires;
 292 }
 293 
 294 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
 295 {
 296         return ktime_to_ns(timer->node.expires);
 297 }
 298 
 299 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
 300 {
 301         return ktime_sub(timer->node.expires, timer->base->get_time());
 302 }
 303 
 304 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 305 {
 306         return timer->base->get_time();
 307 }
 308 
 309 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 310 {
 311         return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
 312                 timer->base->cpu_base->hres_active : 0;
 313 }
 314 
 315 #ifdef CONFIG_HIGH_RES_TIMERS
 316 struct clock_event_device;
 317 
 318 extern void hrtimer_interrupt(struct clock_event_device *dev);
 319 
 320 extern void clock_was_set_delayed(void);
 321 
 322 extern unsigned int hrtimer_resolution;
 323 
 324 #else
 325 
 326 #define hrtimer_resolution      (unsigned int)LOW_RES_NSEC
 327 
 328 static inline void clock_was_set_delayed(void) { }
 329 
 330 #endif
 331 
 332 static inline ktime_t
 333 __hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now)
 334 {
 335         ktime_t rem = ktime_sub(timer->node.expires, now);
 336 
 337         /*
 338          * Adjust relative timers for the extra we added in
 339          * hrtimer_start_range_ns() to prevent short timeouts.
 340          */
 341         if (IS_ENABLED(CONFIG_TIME_LOW_RES) && timer->is_rel)
 342                 rem -= hrtimer_resolution;
 343         return rem;
 344 }
 345 
 346 static inline ktime_t
 347 hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
 348 {
 349         return __hrtimer_expires_remaining_adjusted(timer,
 350                                                     timer->base->get_time());
 351 }
 352 
 353 extern void clock_was_set(void);
 354 #ifdef CONFIG_TIMERFD
 355 extern void timerfd_clock_was_set(void);
 356 #else
 357 static inline void timerfd_clock_was_set(void) { }
 358 #endif
 359 extern void hrtimers_resume(void);
 360 
 361 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
 362 
 363 #ifdef CONFIG_PREEMPT_RT
 364 void hrtimer_cancel_wait_running(const struct hrtimer *timer);
 365 #else
 366 static inline void hrtimer_cancel_wait_running(struct hrtimer *timer)
 367 {
 368         cpu_relax();
 369 }
 370 #endif
 371 
 372 /* Exported timer functions: */
 373 
 374 /* Initialize timers: */
 375 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 376                          enum hrtimer_mode mode);
 377 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
 378                                  enum hrtimer_mode mode);
 379 
 380 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 381 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
 382                                   enum hrtimer_mode mode);
 383 extern void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
 384                                           clockid_t clock_id,
 385                                           enum hrtimer_mode mode);
 386 
 387 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
 388 #else
 389 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
 390                                          clockid_t which_clock,
 391                                          enum hrtimer_mode mode)
 392 {
 393         hrtimer_init(timer, which_clock, mode);
 394 }
 395 
 396 static inline void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
 397                                                  clockid_t clock_id,
 398                                                  enum hrtimer_mode mode)
 399 {
 400         hrtimer_init_sleeper(sl, clock_id, mode);
 401 }
 402 
 403 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
 404 #endif
 405 
 406 /* Basic timer operations: */
 407 extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 408                                    u64 range_ns, const enum hrtimer_mode mode);
 409 
 410 /**
 411  * hrtimer_start - (re)start an hrtimer
 412  * @timer:      the timer to be added
 413  * @tim:        expiry time
 414  * @mode:       timer mode: absolute (HRTIMER_MODE_ABS) or
 415  *              relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
 416  *              softirq based mode is considered for debug purpose only!
 417  */
 418 static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
 419                                  const enum hrtimer_mode mode)
 420 {
 421         hrtimer_start_range_ns(timer, tim, 0, mode);
 422 }
 423 
 424 extern int hrtimer_cancel(struct hrtimer *timer);
 425 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 426 
 427 static inline void hrtimer_start_expires(struct hrtimer *timer,
 428                                          enum hrtimer_mode mode)
 429 {
 430         u64 delta;
 431         ktime_t soft, hard;
 432         soft = hrtimer_get_softexpires(timer);
 433         hard = hrtimer_get_expires(timer);
 434         delta = ktime_to_ns(ktime_sub(hard, soft));
 435         hrtimer_start_range_ns(timer, soft, delta, mode);
 436 }
 437 
 438 void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
 439                                    enum hrtimer_mode mode);
 440 
 441 static inline void hrtimer_restart(struct hrtimer *timer)
 442 {
 443         hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 444 }
 445 
 446 /* Query timers: */
 447 extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);
 448 
 449 static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
 450 {
 451         return __hrtimer_get_remaining(timer, false);
 452 }
 453 
 454 extern u64 hrtimer_get_next_event(void);
 455 extern u64 hrtimer_next_event_without(const struct hrtimer *exclude);
 456 
 457 extern bool hrtimer_active(const struct hrtimer *timer);
 458 
 459 /**
 460  * hrtimer_is_queued = check, whether the timer is on one of the queues
 461  * @timer:      Timer to check
 462  *
 463  * Returns: True if the timer is queued, false otherwise
 464  *
 465  * The function can be used lockless, but it gives only a current snapshot.
 466  */
 467 static inline bool hrtimer_is_queued(struct hrtimer *timer)
 468 {
 469         /* The READ_ONCE pairs with the update functions of timer->state */
 470         return !!(READ_ONCE(timer->state) & HRTIMER_STATE_ENQUEUED);
 471 }
 472 
 473 /*
 474  * Helper function to check, whether the timer is running the callback
 475  * function
 476  */
 477 static inline int hrtimer_callback_running(struct hrtimer *timer)
 478 {
 479         return timer->base->running == timer;
 480 }
 481 
 482 /* Forward a hrtimer so it expires after now: */
 483 extern u64
 484 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 485 
 486 /**
 487  * hrtimer_forward_now - forward the timer expiry so it expires after now
 488  * @timer:      hrtimer to forward
 489  * @interval:   the interval to forward
 490  *
 491  * Forward the timer expiry so it will expire after the current time
 492  * of the hrtimer clock base. Returns the number of overruns.
 493  *
 494  * Can be safely called from the callback function of @timer. If
 495  * called from other contexts @timer must neither be enqueued nor
 496  * running the callback and the caller needs to take care of
 497  * serialization.
 498  *
 499  * Note: This only updates the timer expiry value and does not requeue
 500  * the timer.
 501  */
 502 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 503                                       ktime_t interval)
 504 {
 505         return hrtimer_forward(timer, timer->base->get_time(), interval);
 506 }
 507 
 508 /* Precise sleep: */
 509 
 510 extern int nanosleep_copyout(struct restart_block *, struct timespec64 *);
 511 extern long hrtimer_nanosleep(const struct timespec64 *rqtp,
 512                               const enum hrtimer_mode mode,
 513                               const clockid_t clockid);
 514 
 515 extern int schedule_hrtimeout_range(ktime_t *expires, u64 delta,
 516                                     const enum hrtimer_mode mode);
 517 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
 518                                           u64 delta,
 519                                           const enum hrtimer_mode mode,
 520                                           clockid_t clock_id);
 521 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
 522 
 523 /* Soft interrupt function to run the hrtimer queues: */
 524 extern void hrtimer_run_queues(void);
 525 
 526 /* Bootup initialization: */
 527 extern void __init hrtimers_init(void);
 528 
 529 /* Show pending timers: */
 530 extern void sysrq_timer_list_show(void);
 531 
 532 int hrtimers_prepare_cpu(unsigned int cpu);
 533 #ifdef CONFIG_HOTPLUG_CPU
 534 int hrtimers_dead_cpu(unsigned int cpu);
 535 #else
 536 #define hrtimers_dead_cpu       NULL
 537 #endif
 538 
 539 #endif