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,       /* Time value is absolute */
  34         HRTIMER_MODE_REL,       /* Time value is relative to now */
  35 };
  36
  37 /*
  38  * Return values for the callback function
  39  */
  40 enum hrtimer_restart {
  41         HRTIMER_NORESTART,      /* Timer is not restarted */
  42         HRTIMER_RESTART,        /* Timer must be restarted */
  43 };
  44
  45 /*
  46  * Values to track state of the timer
  47  *
  48  * Possible states:
  49  *
  50  * 0x00         inactive
  51  * 0x01         enqueued into rbtree
  52  * 0x02         callback function running
  53  *
  54  * Special cases:
  55  * 0x03         callback function running and enqueued
  56  *              (was requeued on another CPU)
  57  * 0x09         timer was migrated on CPU hotunplug
  58  * The "callback function running and enqueued" status is only possible on
  59  * SMP. It happens for example when a posix timer expired and the callback
  60  * queued a signal. Between dropping the lock which protects the posix timer
  61  * and reacquiring the base lock of the hrtimer, another CPU can deliver the
  62  * signal and rearm the timer. We have to preserve the callback running state,
  63  * as otherwise the timer could be removed before the softirq code finishes the
  64  * the handling of the timer.
  65  *
  66  * The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state to
  67  * preserve the HRTIMER_STATE_CALLBACK bit in the above scenario.
  68  *
  69  * All state transitions are protected by cpu_base->lock.
  70  */
  71 #define HRTIMER_STATE_INACTIVE  0x00
  72 #define HRTIMER_STATE_ENQUEUED  0x01
  73 #define HRTIMER_STATE_CALLBACK  0x02
  74 #define HRTIMER_STATE_MIGRATE   0x04
  75
  76 /**
  77  * struct hrtimer - the basic hrtimer structure
  78  * @node:       red black tree node for time ordered insertion
  79  * @_expires:   the absolute expiry time in the hrtimers internal
  80  *              representation. The time is related to the clock on
  81  *              which the timer is based. Is setup by adding
  82  *              slack to the _softexpires value. For non range timers
  83  *              identical to _softexpires.
  84  * @_softexpires: the absolute earliest expiry time of the hrtimer.
  85  *              The time which was given as expiry time when the timer
  86  *              was armed.
  87  * @function:   timer expiry callback function
  88  * @base:       pointer to the timer base (per cpu and per clock)
  89  * @state:      state information (See bit values above)
  90  * @cb_entry:   list head to enqueue an expired timer into the callback list
  91  * @start_site: timer statistics field to store the site where the timer
  92  *              was started
  93  * @start_comm: timer statistics field to store the name of the process which
  94  *              started the timer
  95  * @start_pid: timer statistics field to store the pid of the task which
  96  *              started the timer
  97  *
  98  * The hrtimer structure must be initialized by hrtimer_init()
  99  */
 100 struct hrtimer {
 101         struct rb_node                  node;
 102         ktime_t                         _expires;
 103         ktime_t                         _softexpires;
 104         enum hrtimer_restart            (*function)(struct hrtimer *);
 105         struct hrtimer_clock_base       *base;
 106         unsigned long                   state;
 107         struct list_head                cb_entry;
 108 #ifdef CONFIG_TIMER_STATS
 109         int                             start_pid;
 110         void                            *start_site;
 111         char                            start_comm[16];
 112 #endif
 113 };
 114
 115 /**
 116  * struct hrtimer_sleeper - simple sleeper structure
 117  * @timer:      embedded timer structure
 118  * @task:       task to wake up
 119  *
 120  * task is set to NULL, when the timer expires.
 121  */
 122 struct hrtimer_sleeper {
 123         struct hrtimer timer;
 124         struct task_struct *task;
 125 };
 126
 127 /**
 128  * struct hrtimer_clock_base - the timer base for a specific clock
 129  * @cpu_base:           per cpu clock base
 130  * @index:              clock type index for per_cpu support when moving a
 131  *                      timer to a base on another cpu.
 132  * @active:             red black tree root node for the active timers
 133  * @first:              pointer to the timer node which expires first
 134  * @resolution:         the resolution of the clock, in nanoseconds
 135  * @get_time:           function to retrieve the current time of the clock
 136  * @softirq_time:       the time when running the hrtimer queue in the softirq
 137  * @offset:             offset of this clock to the monotonic base
 138  */
 139 struct hrtimer_clock_base {
 140         struct hrtimer_cpu_base *cpu_base;
 141         clockid_t               index;
 142         struct rb_root          active;
 143         struct rb_node          *first;
 144         ktime_t                 resolution;
 145         ktime_t                 (*get_time)(void);
 146         ktime_t                 softirq_time;
 147 #ifdef CONFIG_HIGH_RES_TIMERS
 148         ktime_t                 offset;
 149 #endif
 150 };
 151
 152 #define HRTIMER_MAX_CLOCK_BASES 2
 153
 154 /*
 155  * struct hrtimer_cpu_base - the per cpu clock bases
 156  * @lock:               lock protecting the base and associated clock bases
 157  *                      and timers
 158  * @clock_base:         array of clock bases for this cpu
 159  * @curr_timer:         the timer which is executing a callback right now
 160  * @expires_next:       absolute time of the next event which was scheduled
 161  *                      via clock_set_next_event()
 162  * @hres_active:        State of high resolution mode
 163  * @check_clocks:       Indictator, when set evaluate time source and clock
 164  *                      event devices whether high resolution mode can be
 165  *                      activated.
 166  * @nr_events:          Total number of timer interrupt events
 167  */
 168 struct hrtimer_cpu_base {
 169         spinlock_t                      lock;
 170         struct hrtimer_clock_base       clock_base[HRTIMER_MAX_CLOCK_BASES];
 171 #ifdef CONFIG_HIGH_RES_TIMERS
 172         ktime_t                         expires_next;
 173         int                             hres_active;
 174         unsigned long                   nr_events;
 175 #endif
 176 };
 177
 178 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
 179 {
 180         timer->_expires = time;
 181         timer->_softexpires = time;
 182 }
 183
 184 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
 185 {
 186         timer->_softexpires = time;
 187         timer->_expires = ktime_add_safe(time, delta);
 188 }
 189
 190 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
 191 {
 192         timer->_softexpires = time;
 193         timer->_expires = ktime_add_safe(time, ns_to_ktime(delta));
 194 }
 195
 196 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
 197 {
 198         timer->_expires.tv64 = tv64;
 199         timer->_softexpires.tv64 = tv64;
 200 }
 201
 202 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
 203 {
 204         timer->_expires = ktime_add_safe(timer->_expires, time);
 205         timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
 206 }
 207
 208 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
 209 {
 210         timer->_expires = ktime_add_ns(timer->_expires, ns);
 211         timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
 212 }
 213
 214 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
 215 {
 216         return timer->_expires;
 217 }
 218
 219 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
 220 {
 221         return timer->_softexpires;
 222 }
 223
 224 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
 225 {
 226         return timer->_expires.tv64;
 227 }
 228 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
 229 {
 230         return timer->_softexpires.tv64;
 231 }
 232
 233 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
 234 {
 235         return ktime_to_ns(timer->_expires);
 236 }
 237
 238 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
 239 {
 240     return ktime_sub(timer->_expires, timer->base->get_time());
 241 }
 242
 243 #ifdef CONFIG_HIGH_RES_TIMERS
 244 struct clock_event_device;
 245
 246 extern void clock_was_set(void);
 247 extern void hres_timers_resume(void);
 248 extern void hrtimer_interrupt(struct clock_event_device *dev);
 249
 250 /*
 251  * In high resolution mode the time reference must be read accurate
 252  */
 253 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 254 {
 255         return timer->base->get_time();
 256 }
 257
 258 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 259 {
 260         return timer->base->cpu_base->hres_active;
 261 }
 262
 263 extern void hrtimer_peek_ahead_timers(void);
 264
 265 /*
 266  * The resolution of the clocks. The resolution value is returned in
 267  * the clock_getres() system call to give application programmers an
 268  * idea of the (in)accuracy of timers. Timer values are rounded up to
 269  * this resolution values.
 270  */
 271 # define HIGH_RES_NSEC          1
 272 # define KTIME_HIGH_RES         (ktime_t) { .tv64 = HIGH_RES_NSEC }
 273 # define MONOTONIC_RES_NSEC     HIGH_RES_NSEC
 274 # define KTIME_MONOTONIC_RES    KTIME_HIGH_RES
 275
 276 #else
 277
 278 # define MONOTONIC_RES_NSEC     LOW_RES_NSEC
 279 # define KTIME_MONOTONIC_RES    KTIME_LOW_RES
 280
 281 /*
 282  * clock_was_set() is a NOP for non- high-resolution systems. The
 283  * time-sorted order guarantees that a timer does not expire early and
 284  * is expired in the next softirq when the clock was advanced.
 285  */
 286 static inline void clock_was_set(void) { }
 287 static inline void hrtimer_peek_ahead_timers(void) { }
 288
 289 static inline void hres_timers_resume(void) { }
 290
 291 /*
 292  * In non high resolution mode the time reference is taken from
 293  * the base softirq time variable.
 294  */
 295 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 296 {
 297         return timer->base->softirq_time;
 298 }
 299
 300 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 301 {
 302         return 0;
 303 }
 304 #endif
 305
 306 extern ktime_t ktime_get(void);
 307 extern ktime_t ktime_get_real(void);
 308
 309
 310 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
 311
 312
 313 /* Exported timer functions: */
 314
 315 /* Initialize timers: */
 316 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 317                          enum hrtimer_mode mode);
 318
 319 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 320 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
 321                                   enum hrtimer_mode mode);
 322
 323 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
 324 #else
 325 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
 326                                          clockid_t which_clock,
 327                                          enum hrtimer_mode mode)
 328 {
 329         hrtimer_init(timer, which_clock, mode);
 330 }
 331 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
 332 #endif
 333
 334 /* Basic timer operations: */
 335 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
 336                          const enum hrtimer_mode mode);
 337 extern int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 338                         unsigned long range_ns, const enum hrtimer_mode mode);
 339 extern int
 340 __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 341                          unsigned long delta_ns,
 342                          const enum hrtimer_mode mode, int wakeup);
 343
 344 extern int hrtimer_cancel(struct hrtimer *timer);
 345 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 346
 347 static inline int hrtimer_start_expires(struct hrtimer *timer,
 348                                                 enum hrtimer_mode mode)
 349 {
 350         unsigned long delta;
 351         ktime_t soft, hard;
 352         soft = hrtimer_get_softexpires(timer);
 353         hard = hrtimer_get_expires(timer);
 354         delta = ktime_to_ns(ktime_sub(hard, soft));
 355         return hrtimer_start_range_ns(timer, soft, delta, mode);
 356 }
 357
 358 static inline int hrtimer_restart(struct hrtimer *timer)
 359 {
 360         return hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 361 }
 362
 363 /* Query timers: */
 364 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 365 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
 366
 367 extern ktime_t hrtimer_get_next_event(void);
 368
 369 /*
 370  * A timer is active, when it is enqueued into the rbtree or the callback
 371  * function is running.
 372  */
 373 static inline int hrtimer_active(const struct hrtimer *timer)
 374 {
 375         return timer->state != HRTIMER_STATE_INACTIVE;
 376 }
 377
 378 /*
 379  * Helper function to check, whether the timer is on one of the queues
 380  */
 381 static inline int hrtimer_is_queued(struct hrtimer *timer)
 382 {
 383         return timer->state & HRTIMER_STATE_ENQUEUED;
 384 }
 385
 386 /*
 387  * Helper function to check, whether the timer is running the callback
 388  * function
 389  */
 390 static inline int hrtimer_callback_running(struct hrtimer *timer)
 391 {
 392         return timer->state & HRTIMER_STATE_CALLBACK;
 393 }
 394
 395 /* Forward a hrtimer so it expires after now: */
 396 extern u64
 397 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 398
 399 /* Forward a hrtimer so it expires after the hrtimer's current now */
 400 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 401                                       ktime_t interval)
 402 {
 403         return hrtimer_forward(timer, timer->base->get_time(), interval);
 404 }
 405
 406 /* Precise sleep: */
 407 extern long hrtimer_nanosleep(struct timespec *rqtp,
 408                               struct timespec __user *rmtp,
 409                               const enum hrtimer_mode mode,
 410                               const clockid_t clockid);
 411 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
 412
 413 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 414                                  struct task_struct *tsk);
 415
 416 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
 417                                                 const enum hrtimer_mode mode);
 418 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
 419
 420 /* Soft interrupt function to run the hrtimer queues: */
 421 extern void hrtimer_run_queues(void);
 422 extern void hrtimer_run_pending(void);
 423
 424 /* Bootup initialization: */
 425 extern void __init hrtimers_init(void);
 426
 427 #if BITS_PER_LONG < 64
 428 extern u64 ktime_divns(const ktime_t kt, s64 div);
 429 #else /* BITS_PER_LONG < 64 */
 430 # define ktime_divns(kt, div)           (u64)((kt).tv64 / (div))
 431 #endif
 432
 433 /* Show pending timers: */
 434 extern void sysrq_timer_list_show(void);
 435
 436 /*
 437  * Timer-statistics info:
 438  */
 439 #ifdef CONFIG_TIMER_STATS
 440
 441 extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
 442                                      void *timerf, char *comm,
 443                                      unsigned int timer_flag);
 444
 445 static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
 446 {
 447         timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
 448                                  timer->function, timer->start_comm, 0);
 449 }
 450
 451 extern void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer,
 452                                                  void *addr);
 453
 454 static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
 455 {
 456         __timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0));
 457 }
 458
 459 static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
 460 {
 461         timer->start_site = NULL;
 462 }
 463 #else
 464 static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
 465 {
 466 }
 467
 468 static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
 469 {
 470 }
 471
 472 static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
 473 {
 474 }
 475 #endif
 476
 477 #endif