include/linux/hrtimer.h

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