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/wait.h>
  23 #include <linux/percpu.h>
  24
  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  * 0x02         callback function running
  56  *
  57  * Special cases:
  58  * 0x03         callback function running and enqueued
  59  *              (was requeued on another CPU)
  60  * 0x09         timer was migrated on CPU hotunplug
  61  * The "callback function running and enqueued" status is only possible on
  62  * SMP. It happens for example when a posix timer expired and the callback
  63  * queued a signal. Between dropping the lock which protects the posix timer
  64  * and reacquiring the base lock of the hrtimer, another CPU can deliver the
  65  * signal and rearm the timer. We have to preserve the callback running state,
  66  * as otherwise the timer could be removed before the softirq code finishes the
  67  * the handling of the timer.
  68  *
  69  * The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state to
  70  * preserve the HRTIMER_STATE_CALLBACK bit in the above scenario.
  71  *
  72  * All state transitions are protected by cpu_base->lock.
  73  */
  74 #define HRTIMER_STATE_INACTIVE  0x00
  75 #define HRTIMER_STATE_ENQUEUED  0x01
  76 #define HRTIMER_STATE_CALLBACK  0x02
  77 #define HRTIMER_STATE_MIGRATE   0x04
  78
  79 /**
  80  * struct hrtimer - the basic hrtimer structure
  81  * @node:       red black tree node for time ordered insertion
  82  * @_expires:   the absolute expiry time in the hrtimers internal
  83  *              representation. The time is related to the clock on
  84  *              which the timer is based. Is setup by adding
  85  *              slack to the _softexpires value. For non range timers
  86  *              identical to _softexpires.
  87  * @_softexpires: the absolute earliest expiry time of the hrtimer.
  88  *              The time which was given as expiry time when the timer
  89  *              was armed.
  90  * @function:   timer expiry callback function
  91  * @base:       pointer to the timer base (per cpu and per clock)
  92  * @state:      state information (See bit values above)
  93  * @cb_entry:   list head to enqueue an expired timer into the callback list
  94  * @start_site: timer statistics field to store the site where the timer
  95  *              was started
  96  * @start_comm: timer statistics field to store the name of the process which
  97  *              started the timer
  98  * @start_pid: timer statistics field to store the pid of the task which
  99  *              started the timer
 100  *
 101  * The hrtimer structure must be initialized by hrtimer_init()
 102  */
 103 struct hrtimer {
 104         struct rb_node                  node;
 105         ktime_t                         _expires;
 106         ktime_t                         _softexpires;
 107         enum hrtimer_restart            (*function)(struct hrtimer *);
 108         struct hrtimer_clock_base       *base;
 109         unsigned long                   state;
 110         struct list_head                cb_entry;
 111 #ifdef CONFIG_TIMER_STATS
 112         int                             start_pid;
 113         void                            *start_site;
 114         char                            start_comm[16];
 115 #endif
 116 };
 117
 118 /**
 119  * struct hrtimer_sleeper - simple sleeper structure
 120  * @timer:      embedded timer structure
 121  * @task:       task to wake up
 122  *
 123  * task is set to NULL, when the timer expires.
 124  */
 125 struct hrtimer_sleeper {
 126         struct hrtimer timer;
 127         struct task_struct *task;
 128 };
 129
 130 /**
 131  * struct hrtimer_clock_base - the timer base for a specific clock
 132  * @cpu_base:           per cpu clock base
 133  * @index:              clock type index for per_cpu support when moving a
 134  *                      timer to a base on another cpu.
 135  * @active:             red black tree root node for the active timers
 136  * @first:              pointer to the timer node which expires first
 137  * @resolution:         the resolution of the clock, in nanoseconds
 138  * @get_time:           function to retrieve the current time of the clock
 139  * @softirq_time:       the time when running the hrtimer queue in the softirq
 140  * @offset:             offset of this clock to the monotonic base
 141  */
 142 struct hrtimer_clock_base {
 143         struct hrtimer_cpu_base *cpu_base;
 144         clockid_t               index;
 145         struct rb_root          active;
 146         struct rb_node          *first;
 147         ktime_t                 resolution;
 148         ktime_t                 (*get_time)(void);
 149         ktime_t                 softirq_time;
 150 #ifdef CONFIG_HIGH_RES_TIMERS
 151         ktime_t                 offset;
 152 #endif
 153 };
 154
 155 #define HRTIMER_MAX_CLOCK_BASES 2
 156
 157 /*
 158  * struct hrtimer_cpu_base - the per cpu clock bases
 159  * @lock:               lock protecting the base and associated clock bases
 160  *                      and timers
 161  * @clock_base:         array of clock bases for this cpu
 162  * @curr_timer:         the timer which is executing a callback right now
 163  * @expires_next:       absolute time of the next event which was scheduled
 164  *                      via clock_set_next_event()
 165  * @hres_active:        State of high resolution mode
 166  * @check_clocks:       Indictator, when set evaluate time source and clock
 167  *                      event devices whether high resolution mode can be
 168  *                      activated.
 169  * @nr_events:          Total number of timer interrupt events
 170  */
 171 struct hrtimer_cpu_base {
 172         spinlock_t                      lock;
 173         struct hrtimer_clock_base       clock_base[HRTIMER_MAX_CLOCK_BASES];
 174 #ifdef CONFIG_HIGH_RES_TIMERS
 175         ktime_t                         expires_next;
 176         int                             hres_active;
 177         unsigned long                   nr_events;
 178 #endif
 179 };
 180
 181 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
 182 {
 183         timer->_expires = time;
 184         timer->_softexpires = time;
 185 }
 186
 187 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
 188 {
 189         timer->_softexpires = time;
 190         timer->_expires = ktime_add_safe(time, delta);
 191 }
 192
 193 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
 194 {
 195         timer->_softexpires = time;
 196         timer->_expires = ktime_add_safe(time, ns_to_ktime(delta));
 197 }
 198
 199 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
 200 {
 201         timer->_expires.tv64 = tv64;
 202         timer->_softexpires.tv64 = tv64;
 203 }
 204
 205 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
 206 {
 207         timer->_expires = ktime_add_safe(timer->_expires, time);
 208         timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
 209 }
 210
 211 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
 212 {
 213         timer->_expires = ktime_add_ns(timer->_expires, ns);
 214         timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
 215 }
 216
 217 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
 218 {
 219         return timer->_expires;
 220 }
 221
 222 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
 223 {
 224         return timer->_softexpires;
 225 }
 226
 227 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
 228 {
 229         return timer->_expires.tv64;
 230 }
 231 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
 232 {
 233         return timer->_softexpires.tv64;
 234 }
 235
 236 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
 237 {
 238         return ktime_to_ns(timer->_expires);
 239 }
 240
 241 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
 242 {
 243     return ktime_sub(timer->_expires, timer->base->get_time());
 244 }
 245
 246 #ifdef CONFIG_HIGH_RES_TIMERS
 247 struct clock_event_device;
 248
 249 extern void clock_was_set(void);
 250 extern void hres_timers_resume(void);
 251 extern void hrtimer_interrupt(struct clock_event_device *dev);
 252
 253 /*
 254  * In high resolution mode the time reference must be read accurate
 255  */
 256 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 257 {
 258         return timer->base->get_time();
 259 }
 260
 261 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 262 {
 263         return timer->base->cpu_base->hres_active;
 264 }
 265
 266 extern void hrtimer_peek_ahead_timers(void);
 267
 268 /*
 269  * The resolution of the clocks. The resolution value is returned in
 270  * the clock_getres() system call to give application programmers an
 271  * idea of the (in)accuracy of timers. Timer values are rounded up to
 272  * this resolution values.
 273  */
 274 # define HIGH_RES_NSEC          1
 275 # define KTIME_HIGH_RES         (ktime_t) { .tv64 = HIGH_RES_NSEC }
 276 # define MONOTONIC_RES_NSEC     HIGH_RES_NSEC
 277 # define KTIME_MONOTONIC_RES    KTIME_HIGH_RES
 278
 279 #else
 280
 281 # define MONOTONIC_RES_NSEC     LOW_RES_NSEC
 282 # define KTIME_MONOTONIC_RES    KTIME_LOW_RES
 283
 284 /*
 285  * clock_was_set() is a NOP for non- high-resolution systems. The
 286  * time-sorted order guarantees that a timer does not expire early and
 287  * is expired in the next softirq when the clock was advanced.
 288  */
 289 static inline void clock_was_set(void) { }
 290 static inline void hrtimer_peek_ahead_timers(void) { }
 291
 292 static inline void hres_timers_resume(void) { }
 293
 294 /*
 295  * In non high resolution mode the time reference is taken from
 296  * the base softirq time variable.
 297  */
 298 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 299 {
 300         return timer->base->softirq_time;
 301 }
 302
 303 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 304 {
 305         return 0;
 306 }
 307 #endif
 308
 309 extern ktime_t ktime_get(void);
 310 extern ktime_t ktime_get_real(void);
 311
 312
 313 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
 314
 315
 316 /* Exported timer functions: */
 317
 318 /* Initialize timers: */
 319 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 320                          enum hrtimer_mode mode);
 321
 322 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 323 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
 324                                   enum hrtimer_mode mode);
 325
 326 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
 327 #else
 328 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
 329                                          clockid_t which_clock,
 330                                          enum hrtimer_mode mode)
 331 {
 332         hrtimer_init(timer, which_clock, mode);
 333 }
 334 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
 335 #endif
 336
 337 /* Basic timer operations: */
 338 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
 339                          const enum hrtimer_mode mode);
 340 extern int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 341                         unsigned long range_ns, const enum hrtimer_mode mode);
 342 extern int
 343 __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 344                          unsigned long delta_ns,
 345                          const enum hrtimer_mode mode, int wakeup);
 346
 347 extern int hrtimer_cancel(struct hrtimer *timer);
 348 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 349
 350 static inline int hrtimer_start_expires(struct hrtimer *timer,
 351                                                 enum hrtimer_mode mode)
 352 {
 353         unsigned long delta;
 354         ktime_t soft, hard;
 355         soft = hrtimer_get_softexpires(timer);
 356         hard = hrtimer_get_expires(timer);
 357         delta = ktime_to_ns(ktime_sub(hard, soft));
 358         return hrtimer_start_range_ns(timer, soft, delta, mode);
 359 }
 360
 361 static inline int hrtimer_restart(struct hrtimer *timer)
 362 {
 363         return hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 364 }
 365
 366 /* Query timers: */
 367 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 368 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
 369
 370 extern ktime_t hrtimer_get_next_event(void);
 371
 372 /*
 373  * A timer is active, when it is enqueued into the rbtree or the callback
 374  * function is running.
 375  */
 376 static inline int hrtimer_active(const struct hrtimer *timer)
 377 {
 378         return timer->state != HRTIMER_STATE_INACTIVE;
 379 }
 380
 381 /*
 382  * Helper function to check, whether the timer is on one of the queues
 383  */
 384 static inline int hrtimer_is_queued(struct hrtimer *timer)
 385 {
 386         return timer->state & HRTIMER_STATE_ENQUEUED;
 387 }
 388
 389 /*
 390  * Helper function to check, whether the timer is running the callback
 391  * function
 392  */
 393 static inline int hrtimer_callback_running(struct hrtimer *timer)
 394 {
 395         return timer->state & HRTIMER_STATE_CALLBACK;
 396 }
 397
 398 /* Forward a hrtimer so it expires after now: */
 399 extern u64
 400 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 401
 402 /* Forward a hrtimer so it expires after the hrtimer's current now */
 403 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 404                                       ktime_t interval)
 405 {
 406         return hrtimer_forward(timer, timer->base->get_time(), interval);
 407 }
 408
 409 /* Precise sleep: */
 410 extern long hrtimer_nanosleep(struct timespec *rqtp,
 411                               struct timespec __user *rmtp,
 412                               const enum hrtimer_mode mode,
 413                               const clockid_t clockid);
 414 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
 415
 416 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 417                                  struct task_struct *tsk);
 418
 419 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
 420                                                 const enum hrtimer_mode mode);
 421 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
 422
 423 /* Soft interrupt function to run the hrtimer queues: */
 424 extern void hrtimer_run_queues(void);
 425 extern void hrtimer_run_pending(void);
 426
 427 /* Bootup initialization: */
 428 extern void __init hrtimers_init(void);
 429
 430 #if BITS_PER_LONG < 64
 431 extern u64 ktime_divns(const ktime_t kt, s64 div);
 432 #else /* BITS_PER_LONG < 64 */
 433 # define ktime_divns(kt, div)           (u64)((kt).tv64 / (div))
 434 #endif
 435
 436 /* Show pending timers: */
 437 extern void sysrq_timer_list_show(void);
 438
 439 /*
 440  * Timer-statistics info:
 441  */
 442 #ifdef CONFIG_TIMER_STATS
 443
 444 extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
 445                                      void *timerf, char *comm,
 446                                      unsigned int timer_flag);
 447
 448 static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
 449 {
 450         timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
 451                                  timer->function, timer->start_comm, 0);
 452 }
 453
 454 extern void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer,
 455                                                  void *addr);
 456
 457 static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
 458 {
 459         __timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0));
 460 }
 461
 462 static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
 463 {
 464         timer->start_site = NULL;
 465 }
 466 #else
 467 static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
 468 {
 469 }
 470
 471 static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
 472 {
 473 }
 474
 475 static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
 476 {
 477 }
 478 #endif
 479
 480 #endif