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 enum hrtimer_mode {
  33         HRTIMER_MODE_ABS = 0x0,         /* Time value is absolute */
  34         HRTIMER_MODE_REL = 0x1,         /* Time value is relative to now */
  35         HRTIMER_MODE_PINNED = 0x02,     /* Timer is bound to CPU */
  36         HRTIMER_MODE_ABS_PINNED = 0x02,
  37         HRTIMER_MODE_REL_PINNED = 0x03,
  38 };
  39
  40 /*
  41  * Return values for the callback function
  42  */
  43 enum hrtimer_restart {
  44         HRTIMER_NORESTART,      /* Timer is not restarted */
  45         HRTIMER_RESTART,        /* Timer must be restarted */
  46 };
  47
  48 /*
  49  * Values to track state of the timer
  50  *
  51  * Possible states:
  52  *
  53  * 0x00         inactive
  54  * 0x01         enqueued into rbtree
  55  *
  56  * The callback state is not part of the timer->state because clearing it would
  57  * mean touching the timer after the callback, this makes it impossible to free
  58  * the timer from the callback function.
  59  *
  60  * Therefore we track the callback state in:
  61  *
  62  *      timer->base->cpu_base->running == timer
  63  *
  64  * On SMP it is possible to have a "callback function running and enqueued"
  65  * status. It happens for example when a posix timer expired and the callback
  66  * queued a signal. Between dropping the lock which protects the posix timer
  67  * and reacquiring the base lock of the hrtimer, another CPU can deliver the
  68  * signal and rearm the timer.
  69  *
  70  * All state transitions are protected by cpu_base->lock.
  71  */
  72 #define HRTIMER_STATE_INACTIVE  0x00
  73 #define HRTIMER_STATE_ENQUEUED  0x01
  74
  75 /**
  76  * struct hrtimer - the basic hrtimer structure
  77  * @node:       timerqueue node, which also manages node.expires,
  78  *              the absolute expiry time in the hrtimers internal
  79  *              representation. The time is related to the clock on
  80  *              which the timer is based. Is setup by adding
  81  *              slack to the _softexpires value. For non range timers
  82  *              identical to _softexpires.
  83  * @_softexpires: the absolute earliest expiry time of the hrtimer.
  84  *              The time which was given as expiry time when the timer
  85  *              was armed.
  86  * @function:   timer expiry callback function
  87  * @base:       pointer to the timer base (per cpu and per clock)
  88  * @state:      state information (See bit values above)
  89  * @is_rel:     Set if the timer was armed relative
  90  *
  91  * The hrtimer structure must be initialized by hrtimer_init()
  92  */
  93 struct hrtimer {
  94         struct timerqueue_node          node;
  95         ktime_t                         _softexpires;
  96         enum hrtimer_restart            (*function)(struct hrtimer *);
  97         struct hrtimer_clock_base       *base;
  98         u8                              state;
  99         u8                              is_rel;
 100 };
 101
 102 /**
 103  * struct hrtimer_sleeper - simple sleeper structure
 104  * @timer:      embedded timer structure
 105  * @task:       task to wake up
 106  *
 107  * task is set to NULL, when the timer expires.
 108  */
 109 struct hrtimer_sleeper {
 110         struct hrtimer timer;
 111         struct task_struct *task;
 112 };
 113
 114 #ifdef CONFIG_64BIT
 115 # define HRTIMER_CLOCK_BASE_ALIGN       64
 116 #else
 117 # define HRTIMER_CLOCK_BASE_ALIGN       32
 118 #endif
 119
 120 /**
 121  * struct hrtimer_clock_base - the timer base for a specific clock
 122  * @cpu_base:           per cpu clock base
 123  * @index:              clock type index for per_cpu support when moving a
 124  *                      timer to a base on another cpu.
 125  * @clockid:            clock id for per_cpu support
 126  * @active:             red black tree root node for the active timers
 127  * @get_time:           function to retrieve the current time of the clock
 128  * @offset:             offset of this clock to the monotonic base
 129  */
 130 struct hrtimer_clock_base {
 131         struct hrtimer_cpu_base *cpu_base;
 132         int                     index;
 133         clockid_t               clockid;
 134         struct timerqueue_head  active;
 135         ktime_t                 (*get_time)(void);
 136         ktime_t                 offset;
 137 } __attribute__((__aligned__(HRTIMER_CLOCK_BASE_ALIGN)));
 138
 139 enum  hrtimer_base_type {
 140         HRTIMER_BASE_MONOTONIC,
 141         HRTIMER_BASE_REALTIME,
 142         HRTIMER_BASE_BOOTTIME,
 143         HRTIMER_BASE_TAI,
 144         HRTIMER_MAX_CLOCK_BASES,
 145 };
 146
 147 /*
 148  * struct hrtimer_cpu_base - the per cpu clock bases
 149  * @lock:               lock protecting the base and associated clock bases
 150  *                      and timers
 151  * @seq:                seqcount around __run_hrtimer
 152  * @running:            pointer to the currently running hrtimer
 153  * @cpu:                cpu number
 154  * @active_bases:       Bitfield to mark bases with active timers
 155  * @clock_was_set_seq:  Sequence counter of clock was set events
 156  * @migration_enabled:  The migration of hrtimers to other cpus is enabled
 157  * @nohz_active:        The nohz functionality is enabled
 158  * @expires_next:       absolute time of the next event which was scheduled
 159  *                      via clock_set_next_event()
 160  * @next_timer:         Pointer to the first expiring timer
 161  * @in_hrtirq:          hrtimer_interrupt() is currently executing
 162  * @hres_active:        State of high resolution mode
 163  * @hang_detected:      The last hrtimer interrupt detected a hang
 164  * @nr_events:          Total number of hrtimer interrupt events
 165  * @nr_retries:         Total number of hrtimer interrupt retries
 166  * @nr_hangs:           Total number of hrtimer interrupt hangs
 167  * @max_hang_time:      Maximum time spent in hrtimer_interrupt
 168  * @clock_base:         array of clock bases for this cpu
 169  *
 170  * Note: next_timer is just an optimization for __remove_hrtimer().
 171  *       Do not dereference the pointer because it is not reliable on
 172  *       cross cpu removals.
 173  */
 174 struct hrtimer_cpu_base {
 175         raw_spinlock_t                  lock;
 176         seqcount_t                      seq;
 177         struct hrtimer                  *running;
 178         unsigned int                    cpu;
 179         unsigned int                    active_bases;
 180         unsigned int                    clock_was_set_seq;
 181         bool                            migration_enabled;
 182         bool                            nohz_active;
 183 #ifdef CONFIG_HIGH_RES_TIMERS
 184         unsigned int                    in_hrtirq       : 1,
 185                                         hres_active     : 1,
 186                                         hang_detected   : 1;
 187         ktime_t                         expires_next;
 188         struct hrtimer                  *next_timer;
 189         unsigned int                    nr_events;
 190         unsigned int                    nr_retries;
 191         unsigned int                    nr_hangs;
 192         unsigned int                    max_hang_time;
 193 #endif
 194         struct hrtimer_clock_base       clock_base[HRTIMER_MAX_CLOCK_BASES];
 195 } ____cacheline_aligned;
 196
 197 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
 198 {
 199         BUILD_BUG_ON(sizeof(struct hrtimer_clock_base) > HRTIMER_CLOCK_BASE_ALIGN);
 200
 201         timer->node.expires = time;
 202         timer->_softexpires = time;
 203 }
 204
 205 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
 206 {
 207         timer->_softexpires = time;
 208         timer->node.expires = ktime_add_safe(time, delta);
 209 }
 210
 211 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, u64 delta)
 212 {
 213         timer->_softexpires = time;
 214         timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
 215 }
 216
 217 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
 218 {
 219         timer->node.expires = tv64;
 220         timer->_softexpires = tv64;
 221 }
 222
 223 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
 224 {
 225         timer->node.expires = ktime_add_safe(timer->node.expires, time);
 226         timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
 227 }
 228
 229 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
 230 {
 231         timer->node.expires = ktime_add_ns(timer->node.expires, ns);
 232         timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
 233 }
 234
 235 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
 236 {
 237         return timer->node.expires;
 238 }
 239
 240 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
 241 {
 242         return timer->_softexpires;
 243 }
 244
 245 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
 246 {
 247         return timer->node.expires;
 248 }
 249 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
 250 {
 251         return timer->_softexpires;
 252 }
 253
 254 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
 255 {
 256         return ktime_to_ns(timer->node.expires);
 257 }
 258
 259 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
 260 {
 261         return ktime_sub(timer->node.expires, timer->base->get_time());
 262 }
 263
 264 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 265 {
 266         return timer->base->get_time();
 267 }
 268
 269 #ifdef CONFIG_HIGH_RES_TIMERS
 270 struct clock_event_device;
 271
 272 extern void hrtimer_interrupt(struct clock_event_device *dev);
 273
 274 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 275 {
 276         return timer->base->cpu_base->hres_active;
 277 }
 278
 279 extern void hrtimer_peek_ahead_timers(void);
 280
 281 /*
 282  * The resolution of the clocks. The resolution value is returned in
 283  * the clock_getres() system call to give application programmers an
 284  * idea of the (in)accuracy of timers. Timer values are rounded up to
 285  * this resolution values.
 286  */
 287 # define HIGH_RES_NSEC          1
 288 # define KTIME_HIGH_RES         (HIGH_RES_NSEC)
 289 # define MONOTONIC_RES_NSEC     HIGH_RES_NSEC
 290 # define KTIME_MONOTONIC_RES    KTIME_HIGH_RES
 291
 292 extern void clock_was_set_delayed(void);
 293
 294 extern unsigned int hrtimer_resolution;
 295
 296 #else
 297
 298 # define MONOTONIC_RES_NSEC     LOW_RES_NSEC
 299 # define KTIME_MONOTONIC_RES    KTIME_LOW_RES
 300
 301 #define hrtimer_resolution      (unsigned int)LOW_RES_NSEC
 302
 303 static inline void hrtimer_peek_ahead_timers(void) { }
 304
 305 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 306 {
 307         return 0;
 308 }
 309
 310 static inline void clock_was_set_delayed(void) { }
 311
 312 #endif
 313
 314 static inline ktime_t
 315 __hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now)
 316 {
 317         ktime_t rem = ktime_sub(timer->node.expires, now);
 318
 319         /*
 320          * Adjust relative timers for the extra we added in
 321          * hrtimer_start_range_ns() to prevent short timeouts.
 322          */
 323         if (IS_ENABLED(CONFIG_TIME_LOW_RES) && timer->is_rel)
 324                 rem -= hrtimer_resolution;
 325         return rem;
 326 }
 327
 328 static inline ktime_t
 329 hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
 330 {
 331         return __hrtimer_expires_remaining_adjusted(timer,
 332                                                     timer->base->get_time());
 333 }
 334
 335 extern void clock_was_set(void);
 336 #ifdef CONFIG_TIMERFD
 337 extern void timerfd_clock_was_set(void);
 338 #else
 339 static inline void timerfd_clock_was_set(void) { }
 340 #endif
 341 extern void hrtimers_resume(void);
 342
 343 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
 344
 345
 346 /* Exported timer functions: */
 347
 348 /* Initialize timers: */
 349 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 350                          enum hrtimer_mode mode);
 351
 352 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 353 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
 354                                   enum hrtimer_mode mode);
 355
 356 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
 357 #else
 358 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
 359                                          clockid_t which_clock,
 360                                          enum hrtimer_mode mode)
 361 {
 362         hrtimer_init(timer, which_clock, mode);
 363 }
 364 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
 365 #endif
 366
 367 /* Basic timer operations: */
 368 extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 369                                    u64 range_ns, const enum hrtimer_mode mode);
 370
 371 /**
 372  * hrtimer_start - (re)start an hrtimer on the current CPU
 373  * @timer:      the timer to be added
 374  * @tim:        expiry time
 375  * @mode:       expiry mode: absolute (HRTIMER_MODE_ABS) or
 376  *              relative (HRTIMER_MODE_REL)
 377  */
 378 static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
 379                                  const enum hrtimer_mode mode)
 380 {
 381         hrtimer_start_range_ns(timer, tim, 0, mode);
 382 }
 383
 384 extern int hrtimer_cancel(struct hrtimer *timer);
 385 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 386
 387 static inline void hrtimer_start_expires(struct hrtimer *timer,
 388                                          enum hrtimer_mode mode)
 389 {
 390         u64 delta;
 391         ktime_t soft, hard;
 392         soft = hrtimer_get_softexpires(timer);
 393         hard = hrtimer_get_expires(timer);
 394         delta = ktime_to_ns(ktime_sub(hard, soft));
 395         hrtimer_start_range_ns(timer, soft, delta, mode);
 396 }
 397
 398 static inline void hrtimer_restart(struct hrtimer *timer)
 399 {
 400         hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 401 }
 402
 403 /* Query timers: */
 404 extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);
 405
 406 static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
 407 {
 408         return __hrtimer_get_remaining(timer, false);
 409 }
 410
 411 extern u64 hrtimer_get_next_event(void);
 412
 413 extern bool hrtimer_active(const struct hrtimer *timer);
 414
 415 /*
 416  * Helper function to check, whether the timer is on one of the queues
 417  */
 418 static inline int hrtimer_is_queued(struct hrtimer *timer)
 419 {
 420         return timer->state & HRTIMER_STATE_ENQUEUED;
 421 }
 422
 423 /*
 424  * Helper function to check, whether the timer is running the callback
 425  * function
 426  */
 427 static inline int hrtimer_callback_running(struct hrtimer *timer)
 428 {
 429         return timer->base->cpu_base->running == timer;
 430 }
 431
 432 /* Forward a hrtimer so it expires after now: */
 433 extern u64
 434 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 435
 436 /**
 437  * hrtimer_forward_now - forward the timer expiry so it expires after now
 438  * @timer:      hrtimer to forward
 439  * @interval:   the interval to forward
 440  *
 441  * Forward the timer expiry so it will expire after the current time
 442  * of the hrtimer clock base. Returns the number of overruns.
 443  *
 444  * Can be safely called from the callback function of @timer. If
 445  * called from other contexts @timer must neither be enqueued nor
 446  * running the callback and the caller needs to take care of
 447  * serialization.
 448  *
 449  * Note: This only updates the timer expiry value and does not requeue
 450  * the timer.
 451  */
 452 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 453                                       ktime_t interval)
 454 {
 455         return hrtimer_forward(timer, timer->base->get_time(), interval);
 456 }
 457
 458 /* Precise sleep: */
 459 extern long hrtimer_nanosleep(struct timespec *rqtp,
 460                               struct timespec __user *rmtp,
 461                               const enum hrtimer_mode mode,
 462                               const clockid_t clockid);
 463 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
 464
 465 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 466                                  struct task_struct *tsk);
 467
 468 extern int schedule_hrtimeout_range(ktime_t *expires, u64 delta,
 469                                                 const enum hrtimer_mode mode);
 470 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
 471                                           u64 delta,
 472                                           const enum hrtimer_mode mode,
 473                                           int clock);
 474 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
 475
 476 /* Soft interrupt function to run the hrtimer queues: */
 477 extern void hrtimer_run_queues(void);
 478
 479 /* Bootup initialization: */
 480 extern void __init hrtimers_init(void);
 481
 482 /* Show pending timers: */
 483 extern void sysrq_timer_list_show(void);
 484
 485 int hrtimers_prepare_cpu(unsigned int cpu);
 486 #ifdef CONFIG_HOTPLUG_CPU
 487 int hrtimers_dead_cpu(unsigned int cpu);
 488 #else
 489 #define hrtimers_dead_cpu       NULL
 490 #endif
 491
 492 #endif