linux/include/linux/hrtimer.h
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   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/wait.h>
  23#include <linux/percpu.h>
  24#include <linux/timer.h>
  25#include <linux/timerqueue.h>
  26
  27struct hrtimer_clock_base;
  28struct hrtimer_cpu_base;
  29
  30/*
  31 * Mode arguments of xxx_hrtimer functions:
  32 */
  33enum hrtimer_mode {
  34        HRTIMER_MODE_ABS = 0x0,         /* Time value is absolute */
  35        HRTIMER_MODE_REL = 0x1,         /* Time value is relative to now */
  36        HRTIMER_MODE_PINNED = 0x02,     /* Timer is bound to CPU */
  37        HRTIMER_MODE_ABS_PINNED = 0x02,
  38        HRTIMER_MODE_REL_PINNED = 0x03,
  39};
  40
  41/*
  42 * Return values for the callback function
  43 */
  44enum hrtimer_restart {
  45        HRTIMER_NORESTART,      /* Timer is not restarted */
  46        HRTIMER_RESTART,        /* Timer must be restarted */
  47};
  48
  49/*
  50 * Values to track state of the timer
  51 *
  52 * Possible states:
  53 *
  54 * 0x00         inactive
  55 * 0x01         enqueued into rbtree
  56 * 0x02         callback function running
  57 * 0x04         timer is migrated to another cpu
  58 *
  59 * Special cases:
  60 * 0x03         callback function running and enqueued
  61 *              (was requeued on another CPU)
  62 * 0x05         timer was migrated on CPU hotunplug
  63 *
  64 * The "callback function running and enqueued" status is only possible on
  65 * SMP. 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. We have to preserve the callback running state,
  69 * as otherwise the timer could be removed before the softirq code finishes the
  70 * the handling of the timer.
  71 *
  72 * The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state
  73 * to preserve the HRTIMER_STATE_CALLBACK in the above scenario. This
  74 * also affects HRTIMER_STATE_MIGRATE where the preservation is not
  75 * necessary. HRTIMER_STATE_MIGRATE is cleared after the timer is
  76 * enqueued on the new cpu.
  77 *
  78 * All state transitions are protected by cpu_base->lock.
  79 */
  80#define HRTIMER_STATE_INACTIVE  0x00
  81#define HRTIMER_STATE_ENQUEUED  0x01
  82#define HRTIMER_STATE_CALLBACK  0x02
  83#define HRTIMER_STATE_MIGRATE   0x04
  84
  85/**
  86 * struct hrtimer - the basic hrtimer structure
  87 * @node:       timerqueue node, which also manages node.expires,
  88 *              the absolute expiry time in the hrtimers internal
  89 *              representation. The time is related to the clock on
  90 *              which the timer is based. Is setup by adding
  91 *              slack to the _softexpires value. For non range timers
  92 *              identical to _softexpires.
  93 * @_softexpires: the absolute earliest expiry time of the hrtimer.
  94 *              The time which was given as expiry time when the timer
  95 *              was armed.
  96 * @function:   timer expiry callback function
  97 * @base:       pointer to the timer base (per cpu and per clock)
  98 * @state:      state information (See bit values above)
  99 * @start_site: timer statistics field to store the site where the timer
 100 *              was started
 101 * @start_comm: timer statistics field to store the name of the process which
 102 *              started the timer
 103 * @start_pid: timer statistics field to store the pid of the task which
 104 *              started the timer
 105 *
 106 * The hrtimer structure must be initialized by hrtimer_init()
 107 */
 108struct hrtimer {
 109        struct timerqueue_node          node;
 110        ktime_t                         _softexpires;
 111        enum hrtimer_restart            (*function)(struct hrtimer *);
 112        struct hrtimer_clock_base       *base;
 113        unsigned long                   state;
 114#ifdef CONFIG_TIMER_STATS
 115        int                             start_pid;
 116        void                            *start_site;
 117        char                            start_comm[16];
 118#endif
 119};
 120
 121/**
 122 * struct hrtimer_sleeper - simple sleeper structure
 123 * @timer:      embedded timer structure
 124 * @task:       task to wake up
 125 *
 126 * task is set to NULL, when the timer expires.
 127 */
 128struct hrtimer_sleeper {
 129        struct hrtimer timer;
 130        struct task_struct *task;
 131};
 132
 133/**
 134 * struct hrtimer_clock_base - the timer base for a specific clock
 135 * @cpu_base:           per cpu clock base
 136 * @index:              clock type index for per_cpu support when moving a
 137 *                      timer to a base on another cpu.
 138 * @clockid:            clock id for per_cpu support
 139 * @active:             red black tree root node for the active timers
 140 * @resolution:         the resolution of the clock, in nanoseconds
 141 * @get_time:           function to retrieve the current time of the clock
 142 * @softirq_time:       the time when running the hrtimer queue in the softirq
 143 * @offset:             offset of this clock to the monotonic base
 144 */
 145struct hrtimer_clock_base {
 146        struct hrtimer_cpu_base *cpu_base;
 147        int                     index;
 148        clockid_t               clockid;
 149        struct timerqueue_head  active;
 150        ktime_t                 resolution;
 151        ktime_t                 (*get_time)(void);
 152        ktime_t                 softirq_time;
 153        ktime_t                 offset;
 154};
 155
 156enum  hrtimer_base_type {
 157        HRTIMER_BASE_MONOTONIC,
 158        HRTIMER_BASE_REALTIME,
 159        HRTIMER_BASE_BOOTTIME,
 160        HRTIMER_MAX_CLOCK_BASES,
 161};
 162
 163/*
 164 * struct hrtimer_cpu_base - the per cpu clock bases
 165 * @lock:               lock protecting the base and associated clock bases
 166 *                      and timers
 167 * @active_bases:       Bitfield to mark bases with active timers
 168 * @clock_was_set:      Indicates that clock was set from irq context.
 169 * @expires_next:       absolute time of the next event which was scheduled
 170 *                      via clock_set_next_event()
 171 * @hres_active:        State of high resolution mode
 172 * @hang_detected:      The last hrtimer interrupt detected a hang
 173 * @nr_events:          Total number of hrtimer interrupt events
 174 * @nr_retries:         Total number of hrtimer interrupt retries
 175 * @nr_hangs:           Total number of hrtimer interrupt hangs
 176 * @max_hang_time:      Maximum time spent in hrtimer_interrupt
 177 * @clock_base:         array of clock bases for this cpu
 178 */
 179struct hrtimer_cpu_base {
 180        raw_spinlock_t                  lock;
 181        unsigned int                    active_bases;
 182        unsigned int                    clock_was_set;
 183#ifdef CONFIG_HIGH_RES_TIMERS
 184        ktime_t                         expires_next;
 185        int                             hres_active;
 186        int                             hang_detected;
 187        unsigned long                   nr_events;
 188        unsigned long                   nr_retries;
 189        unsigned long                   nr_hangs;
 190        ktime_t                         max_hang_time;
 191#endif
 192        struct hrtimer_clock_base       clock_base[HRTIMER_MAX_CLOCK_BASES];
 193};
 194
 195static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
 196{
 197        timer->node.expires = time;
 198        timer->_softexpires = time;
 199}
 200
 201static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
 202{
 203        timer->_softexpires = time;
 204        timer->node.expires = ktime_add_safe(time, delta);
 205}
 206
 207static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
 208{
 209        timer->_softexpires = time;
 210        timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
 211}
 212
 213static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
 214{
 215        timer->node.expires.tv64 = tv64;
 216        timer->_softexpires.tv64 = tv64;
 217}
 218
 219static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
 220{
 221        timer->node.expires = ktime_add_safe(timer->node.expires, time);
 222        timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
 223}
 224
 225static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
 226{
 227        timer->node.expires = ktime_add_ns(timer->node.expires, ns);
 228        timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
 229}
 230
 231static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
 232{
 233        return timer->node.expires;
 234}
 235
 236static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
 237{
 238        return timer->_softexpires;
 239}
 240
 241static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
 242{
 243        return timer->node.expires.tv64;
 244}
 245static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
 246{
 247        return timer->_softexpires.tv64;
 248}
 249
 250static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
 251{
 252        return ktime_to_ns(timer->node.expires);
 253}
 254
 255static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
 256{
 257        return ktime_sub(timer->node.expires, timer->base->get_time());
 258}
 259
 260#ifdef CONFIG_HIGH_RES_TIMERS
 261struct clock_event_device;
 262
 263extern void hrtimer_interrupt(struct clock_event_device *dev);
 264
 265/*
 266 * In high resolution mode the time reference must be read accurate
 267 */
 268static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 269{
 270        return timer->base->get_time();
 271}
 272
 273static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 274{
 275        return timer->base->cpu_base->hres_active;
 276}
 277
 278extern void hrtimer_peek_ahead_timers(void);
 279
 280/*
 281 * The resolution of the clocks. The resolution value is returned in
 282 * the clock_getres() system call to give application programmers an
 283 * idea of the (in)accuracy of timers. Timer values are rounded up to
 284 * this resolution values.
 285 */
 286# define HIGH_RES_NSEC          1
 287# define KTIME_HIGH_RES         (ktime_t) { .tv64 = HIGH_RES_NSEC }
 288# define MONOTONIC_RES_NSEC     HIGH_RES_NSEC
 289# define KTIME_MONOTONIC_RES    KTIME_HIGH_RES
 290
 291extern void clock_was_set_delayed(void);
 292
 293#else
 294
 295# define MONOTONIC_RES_NSEC     LOW_RES_NSEC
 296# define KTIME_MONOTONIC_RES    KTIME_LOW_RES
 297
 298static inline void hrtimer_peek_ahead_timers(void) { }
 299
 300/*
 301 * In non high resolution mode the time reference is taken from
 302 * the base softirq time variable.
 303 */
 304static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 305{
 306        return timer->base->softirq_time;
 307}
 308
 309static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 310{
 311        return 0;
 312}
 313
 314static inline void clock_was_set_delayed(void) { }
 315
 316#endif
 317
 318extern void clock_was_set(void);
 319#ifdef CONFIG_TIMERFD
 320extern void timerfd_clock_was_set(void);
 321#else
 322static inline void timerfd_clock_was_set(void) { }
 323#endif
 324extern void hrtimers_resume(void);
 325
 326extern ktime_t ktime_get(void);
 327extern ktime_t ktime_get_real(void);
 328extern ktime_t ktime_get_boottime(void);
 329extern ktime_t ktime_get_monotonic_offset(void);
 330extern ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot);
 331
 332DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
 333
 334
 335/* Exported timer functions: */
 336
 337/* Initialize timers: */
 338extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 339                         enum hrtimer_mode mode);
 340
 341#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 342extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
 343                                  enum hrtimer_mode mode);
 344
 345extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
 346#else
 347static inline void hrtimer_init_on_stack(struct hrtimer *timer,
 348                                         clockid_t which_clock,
 349                                         enum hrtimer_mode mode)
 350{
 351        hrtimer_init(timer, which_clock, mode);
 352}
 353static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
 354#endif
 355
 356/* Basic timer operations: */
 357extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
 358                         const enum hrtimer_mode mode);
 359extern int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 360                        unsigned long range_ns, const enum hrtimer_mode mode);
 361extern int
 362__hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 363                         unsigned long delta_ns,
 364                         const enum hrtimer_mode mode, int wakeup);
 365
 366extern int hrtimer_cancel(struct hrtimer *timer);
 367extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 368
 369static inline int hrtimer_start_expires(struct hrtimer *timer,
 370                                                enum hrtimer_mode mode)
 371{
 372        unsigned long delta;
 373        ktime_t soft, hard;
 374        soft = hrtimer_get_softexpires(timer);
 375        hard = hrtimer_get_expires(timer);
 376        delta = ktime_to_ns(ktime_sub(hard, soft));
 377        return hrtimer_start_range_ns(timer, soft, delta, mode);
 378}
 379
 380static inline int hrtimer_restart(struct hrtimer *timer)
 381{
 382        return hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 383}
 384
 385/* Query timers: */
 386extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 387extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
 388
 389extern ktime_t hrtimer_get_next_event(void);
 390
 391/*
 392 * A timer is active, when it is enqueued into the rbtree or the
 393 * callback function is running or it's in the state of being migrated
 394 * to another cpu.
 395 */
 396static inline int hrtimer_active(const struct hrtimer *timer)
 397{
 398        return timer->state != HRTIMER_STATE_INACTIVE;
 399}
 400
 401/*
 402 * Helper function to check, whether the timer is on one of the queues
 403 */
 404static inline int hrtimer_is_queued(struct hrtimer *timer)
 405{
 406        return timer->state & HRTIMER_STATE_ENQUEUED;
 407}
 408
 409/*
 410 * Helper function to check, whether the timer is running the callback
 411 * function
 412 */
 413static inline int hrtimer_callback_running(struct hrtimer *timer)
 414{
 415        return timer->state & HRTIMER_STATE_CALLBACK;
 416}
 417
 418/* Forward a hrtimer so it expires after now: */
 419extern u64
 420hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 421
 422/* Forward a hrtimer so it expires after the hrtimer's current now */
 423static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 424                                      ktime_t interval)
 425{
 426        return hrtimer_forward(timer, timer->base->get_time(), interval);
 427}
 428
 429/* Precise sleep: */
 430extern long hrtimer_nanosleep(struct timespec *rqtp,
 431                              struct timespec __user *rmtp,
 432                              const enum hrtimer_mode mode,
 433                              const clockid_t clockid);
 434extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
 435
 436extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 437                                 struct task_struct *tsk);
 438
 439extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
 440                                                const enum hrtimer_mode mode);
 441extern int schedule_hrtimeout_range_clock(ktime_t *expires,
 442                unsigned long delta, const enum hrtimer_mode mode, int clock);
 443extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
 444
 445/* Soft interrupt function to run the hrtimer queues: */
 446extern void hrtimer_run_queues(void);
 447extern void hrtimer_run_pending(void);
 448
 449/* Bootup initialization: */
 450extern void __init hrtimers_init(void);
 451
 452#if BITS_PER_LONG < 64
 453extern u64 ktime_divns(const ktime_t kt, s64 div);
 454#else /* BITS_PER_LONG < 64 */
 455# define ktime_divns(kt, div)           (u64)((kt).tv64 / (div))
 456#endif
 457
 458/* Show pending timers: */
 459extern void sysrq_timer_list_show(void);
 460
 461#endif
 462
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