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 #include <linux/timer.h>
  25 #include <linux/timerqueue.h>
  26
  27 struct hrtimer_clock_base;
  28 struct hrtimer_cpu_base;
  29
  30 /*
  31  * Mode arguments of xxx_hrtimer functions:
  32  */
  33 enum 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  */
  44 enum 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_pid: timer statistics field to store the pid of the task which
 100  *              started the timer
 101  * @start_site: timer statistics field to store the site where the timer
 102  *              was started
 103  * @start_comm: timer statistics field to store the name of the process which
 104  *              started the timer
 105  *
 106  * The hrtimer structure must be initialized by hrtimer_init()
 107  */
 108 struct 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  */
 128 struct 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  * @get_time:           function to retrieve the current time of the clock
 141  * @softirq_time:       the time when running the hrtimer queue in the softirq
 142  * @offset:             offset of this clock to the monotonic base
 143  */
 144 struct hrtimer_clock_base {
 145         struct hrtimer_cpu_base *cpu_base;
 146         int                     index;
 147         clockid_t               clockid;
 148         struct timerqueue_head  active;
 149         ktime_t                 (*get_time)(void);
 150         ktime_t                 softirq_time;
 151         ktime_t                 offset;
 152 };
 153
 154 enum  hrtimer_base_type {
 155         HRTIMER_BASE_MONOTONIC,
 156         HRTIMER_BASE_REALTIME,
 157         HRTIMER_BASE_BOOTTIME,
 158         HRTIMER_BASE_TAI,
 159         HRTIMER_MAX_CLOCK_BASES,
 160 };
 161
 162 /*
 163  * struct hrtimer_cpu_base - the per cpu clock bases
 164  * @lock:               lock protecting the base and associated clock bases
 165  *                      and timers
 166  * @cpu:                cpu number
 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  * @in_hrtirq:          hrtimer_interrupt() is currently executing
 172  * @hres_active:        State of high resolution mode
 173  * @hang_detected:      The last hrtimer interrupt detected a hang
 174  * @nr_events:          Total number of hrtimer interrupt events
 175  * @nr_retries:         Total number of hrtimer interrupt retries
 176  * @nr_hangs:           Total number of hrtimer interrupt hangs
 177  * @max_hang_time:      Maximum time spent in hrtimer_interrupt
 178  * @clock_base:         array of clock bases for this cpu
 179  */
 180 struct hrtimer_cpu_base {
 181         raw_spinlock_t                  lock;
 182         unsigned int                    cpu;
 183         unsigned int                    active_bases;
 184         unsigned int                    clock_was_set;
 185 #ifdef CONFIG_HIGH_RES_TIMERS
 186         ktime_t                         expires_next;
 187         int                             in_hrtirq;
 188         int                             hres_active;
 189         int                             hang_detected;
 190         unsigned int                    nr_events;
 191         unsigned int                    nr_retries;
 192         unsigned int                    nr_hangs;
 193         unsigned int                    max_hang_time;
 194 #endif
 195         struct hrtimer_clock_base       clock_base[HRTIMER_MAX_CLOCK_BASES];
 196 };
 197
 198 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
 199 {
 200         timer->node.expires = time;
 201         timer->_softexpires = time;
 202 }
 203
 204 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
 205 {
 206         timer->_softexpires = time;
 207         timer->node.expires = ktime_add_safe(time, delta);
 208 }
 209
 210 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
 211 {
 212         timer->_softexpires = time;
 213         timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
 214 }
 215
 216 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
 217 {
 218         timer->node.expires.tv64 = tv64;
 219         timer->_softexpires.tv64 = tv64;
 220 }
 221
 222 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
 223 {
 224         timer->node.expires = ktime_add_safe(timer->node.expires, time);
 225         timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
 226 }
 227
 228 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
 229 {
 230         timer->node.expires = ktime_add_ns(timer->node.expires, ns);
 231         timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
 232 }
 233
 234 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
 235 {
 236         return timer->node.expires;
 237 }
 238
 239 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
 240 {
 241         return timer->_softexpires;
 242 }
 243
 244 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
 245 {
 246         return timer->node.expires.tv64;
 247 }
 248 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
 249 {
 250         return timer->_softexpires.tv64;
 251 }
 252
 253 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
 254 {
 255         return ktime_to_ns(timer->node.expires);
 256 }
 257
 258 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
 259 {
 260         return ktime_sub(timer->node.expires, timer->base->get_time());
 261 }
 262
 263 #ifdef CONFIG_HIGH_RES_TIMERS
 264 struct clock_event_device;
 265
 266 extern void hrtimer_interrupt(struct clock_event_device *dev);
 267
 268 /*
 269  * In high resolution mode the time reference must be read accurate
 270  */
 271 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 272 {
 273         return timer->base->get_time();
 274 }
 275
 276 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 277 {
 278         return timer->base->cpu_base->hres_active;
 279 }
 280
 281 extern void hrtimer_peek_ahead_timers(void);
 282
 283 /*
 284  * The resolution of the clocks. The resolution value is returned in
 285  * the clock_getres() system call to give application programmers an
 286  * idea of the (in)accuracy of timers. Timer values are rounded up to
 287  * this resolution values.
 288  */
 289 # define HIGH_RES_NSEC          1
 290 # define KTIME_HIGH_RES         (ktime_t) { .tv64 = HIGH_RES_NSEC }
 291 # define MONOTONIC_RES_NSEC     HIGH_RES_NSEC
 292 # define KTIME_MONOTONIC_RES    KTIME_HIGH_RES
 293
 294 extern void clock_was_set_delayed(void);
 295
 296 extern unsigned int hrtimer_resolution;
 297
 298 #else
 299
 300 # define MONOTONIC_RES_NSEC     LOW_RES_NSEC
 301 # define KTIME_MONOTONIC_RES    KTIME_LOW_RES
 302
 303 #define hrtimer_resolution      LOW_RES_NSEC
 304
 305 static inline void hrtimer_peek_ahead_timers(void) { }
 306
 307 /*
 308  * In non high resolution mode the time reference is taken from
 309  * the base softirq time variable.
 310  */
 311 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 312 {
 313         return timer->base->softirq_time;
 314 }
 315
 316 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 317 {
 318         return 0;
 319 }
 320
 321 static inline void clock_was_set_delayed(void) { }
 322
 323 #endif
 324
 325 extern void clock_was_set(void);
 326 #ifdef CONFIG_TIMERFD
 327 extern void timerfd_clock_was_set(void);
 328 #else
 329 static inline void timerfd_clock_was_set(void) { }
 330 #endif
 331 extern void hrtimers_resume(void);
 332
 333 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
 334
 335
 336 /* Exported timer functions: */
 337
 338 /* Initialize timers: */
 339 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 340                          enum hrtimer_mode mode);
 341
 342 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 343 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
 344                                   enum hrtimer_mode mode);
 345
 346 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
 347 #else
 348 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
 349                                          clockid_t which_clock,
 350                                          enum hrtimer_mode mode)
 351 {
 352         hrtimer_init(timer, which_clock, mode);
 353 }
 354 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
 355 #endif
 356
 357 /* Basic timer operations: */
 358 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
 359                          const enum hrtimer_mode mode);
 360 extern int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 361                         unsigned long range_ns, const enum hrtimer_mode mode);
 362 extern int
 363 __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 364                          unsigned long delta_ns,
 365                          const enum hrtimer_mode mode, int wakeup);
 366
 367 extern int hrtimer_cancel(struct hrtimer *timer);
 368 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 369
 370 static inline int hrtimer_start_expires(struct hrtimer *timer,
 371                                                 enum hrtimer_mode mode)
 372 {
 373         unsigned long delta;
 374         ktime_t soft, hard;
 375         soft = hrtimer_get_softexpires(timer);
 376         hard = hrtimer_get_expires(timer);
 377         delta = ktime_to_ns(ktime_sub(hard, soft));
 378         return hrtimer_start_range_ns(timer, soft, delta, mode);
 379 }
 380
 381 static inline int hrtimer_restart(struct hrtimer *timer)
 382 {
 383         return hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 384 }
 385
 386 /* Query timers: */
 387 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 388
 389 extern 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  */
 396 static 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  */
 404 static 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  */
 413 static 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: */
 419 extern u64
 420 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 421
 422 /**
 423  * hrtimer_forward_now - forward the timer expiry so it expires after now
 424  * @timer:      hrtimer to forward
 425  * @interval:   the interval to forward
 426  *
 427  * Forward the timer expiry so it will expire after the current time
 428  * of the hrtimer clock base. Returns the number of overruns.
 429  *
 430  * Can be safely called from the callback function of @timer. If
 431  * called from other contexts @timer must neither be enqueued nor
 432  * running the callback and the caller needs to take care of
 433  * serialization.
 434  *
 435  * Note: This only updates the timer expiry value and does not requeue
 436  * the timer.
 437  */
 438 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 439                                       ktime_t interval)
 440 {
 441         return hrtimer_forward(timer, timer->base->get_time(), interval);
 442 }
 443
 444 /* Precise sleep: */
 445 extern long hrtimer_nanosleep(struct timespec *rqtp,
 446                               struct timespec __user *rmtp,
 447                               const enum hrtimer_mode mode,
 448                               const clockid_t clockid);
 449 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
 450
 451 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 452                                  struct task_struct *tsk);
 453
 454 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
 455                                                 const enum hrtimer_mode mode);
 456 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
 457                 unsigned long delta, const enum hrtimer_mode mode, int clock);
 458 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
 459
 460 /* Soft interrupt function to run the hrtimer queues: */
 461 extern void hrtimer_run_queues(void);
 462 extern void hrtimer_run_pending(void);
 463
 464 /* Bootup initialization: */
 465 extern void __init hrtimers_init(void);
 466
 467 /* Show pending timers: */
 468 extern void sysrq_timer_list_show(void);
 469
 470 #endif