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  *
  57  * The callback state is not part of the timer->state because clearing it would
  58  * mean touching the timer after the callback, this makes it impossible to free
  59  * the timer from the callback function.
  60  *
  61  * Therefore we track the callback state in:
  62  *
  63  *      timer->base->cpu_base->running == timer
  64  *
  65  * On SMP it is possible to have a "callback function running and enqueued"
  66  * status. It happens for example when a posix timer expired and the callback
  67  * queued a signal. Between dropping the lock which protects the posix timer
  68  * and reacquiring the base lock of the hrtimer, another CPU can deliver the
  69  * signal and rearm the timer.
  70  *
  71  * All state transitions are protected by cpu_base->lock.
  72  */
  73 #define HRTIMER_STATE_INACTIVE  0x00
  74 #define HRTIMER_STATE_ENQUEUED  0x01
  75
  76 /**
  77  * struct hrtimer - the basic hrtimer structure
  78  * @node:       timerqueue node, which also manages node.expires,
  79  *              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  * @start_pid: timer statistics field to store the pid of the task which
  91  *              started the timer
  92  * @start_site: timer statistics field to store the site where the timer
  93  *              was started
  94  * @start_comm: timer statistics field to store the name of the process which
  95  *              started the timer
  96  *
  97  * The hrtimer structure must be initialized by hrtimer_init()
  98  */
  99 struct hrtimer {
 100         struct timerqueue_node          node;
 101         ktime_t                         _softexpires;
 102         enum hrtimer_restart            (*function)(struct hrtimer *);
 103         struct hrtimer_clock_base       *base;
 104         unsigned long                   state;
 105 #ifdef CONFIG_TIMER_STATS
 106         int                             start_pid;
 107         void                            *start_site;
 108         char                            start_comm[16];
 109 #endif
 110 };
 111
 112 /**
 113  * struct hrtimer_sleeper - simple sleeper structure
 114  * @timer:      embedded timer structure
 115  * @task:       task to wake up
 116  *
 117  * task is set to NULL, when the timer expires.
 118  */
 119 struct hrtimer_sleeper {
 120         struct hrtimer timer;
 121         struct task_struct *task;
 122 };
 123
 124 #ifdef CONFIG_64BIT
 125 # define HRTIMER_CLOCK_BASE_ALIGN       64
 126 #else
 127 # define HRTIMER_CLOCK_BASE_ALIGN       32
 128 #endif
 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  * @clockid:            clock id for per_cpu support
 136  * @active:             red black tree root node for the active timers
 137  * @get_time:           function to retrieve the current time of the clock
 138  * @offset:             offset of this clock to the monotonic base
 139  */
 140 struct hrtimer_clock_base {
 141         struct hrtimer_cpu_base *cpu_base;
 142         int                     index;
 143         clockid_t               clockid;
 144         struct timerqueue_head  active;
 145         ktime_t                 (*get_time)(void);
 146         ktime_t                 offset;
 147 } __attribute__((__aligned__(HRTIMER_CLOCK_BASE_ALIGN)));
 148
 149 enum  hrtimer_base_type {
 150         HRTIMER_BASE_MONOTONIC,
 151         HRTIMER_BASE_REALTIME,
 152         HRTIMER_BASE_BOOTTIME,
 153         HRTIMER_BASE_TAI,
 154         HRTIMER_MAX_CLOCK_BASES,
 155 };
 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  * @seq:                seqcount around __run_hrtimer
 162  * @running:            pointer to the currently running hrtimer
 163  * @cpu:                cpu number
 164  * @active_bases:       Bitfield to mark bases with active timers
 165  * @clock_was_set_seq:  Sequence counter of clock was set events
 166  * @migration_enabled:  The migration of hrtimers to other cpus is enabled
 167  * @nohz_active:        The nohz functionality is enabled
 168  * @expires_next:       absolute time of the next event which was scheduled
 169  *                      via clock_set_next_event()
 170  * @next_timer:         Pointer to the first expiring timer
 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  * Note: next_timer is just an optimization for __remove_hrtimer().
 181  *       Do not dereference the pointer because it is not reliable on
 182  *       cross cpu removals.
 183  */
 184 struct hrtimer_cpu_base {
 185         raw_spinlock_t                  lock;
 186         seqcount_t                      seq;
 187         struct hrtimer                  *running;
 188         unsigned int                    cpu;
 189         unsigned int                    active_bases;
 190         unsigned int                    clock_was_set_seq;
 191         bool                            migration_enabled;
 192         bool                            nohz_active;
 193 #ifdef CONFIG_HIGH_RES_TIMERS
 194         unsigned int                    in_hrtirq       : 1,
 195                                         hres_active     : 1,
 196                                         hang_detected   : 1;
 197         ktime_t                         expires_next;
 198         struct hrtimer                  *next_timer;
 199         unsigned int                    nr_events;
 200         unsigned int                    nr_retries;
 201         unsigned int                    nr_hangs;
 202         unsigned int                    max_hang_time;
 203 #endif
 204         struct hrtimer_clock_base       clock_base[HRTIMER_MAX_CLOCK_BASES];
 205 } ____cacheline_aligned;
 206
 207 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
 208 {
 209         BUILD_BUG_ON(sizeof(struct hrtimer_clock_base) > HRTIMER_CLOCK_BASE_ALIGN);
 210
 211         timer->node.expires = time;
 212         timer->_softexpires = time;
 213 }
 214
 215 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
 216 {
 217         timer->_softexpires = time;
 218         timer->node.expires = ktime_add_safe(time, delta);
 219 }
 220
 221 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
 222 {
 223         timer->_softexpires = time;
 224         timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
 225 }
 226
 227 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
 228 {
 229         timer->node.expires.tv64 = tv64;
 230         timer->_softexpires.tv64 = tv64;
 231 }
 232
 233 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
 234 {
 235         timer->node.expires = ktime_add_safe(timer->node.expires, time);
 236         timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
 237 }
 238
 239 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
 240 {
 241         timer->node.expires = ktime_add_ns(timer->node.expires, ns);
 242         timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
 243 }
 244
 245 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
 246 {
 247         return timer->node.expires;
 248 }
 249
 250 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
 251 {
 252         return timer->_softexpires;
 253 }
 254
 255 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
 256 {
 257         return timer->node.expires.tv64;
 258 }
 259 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
 260 {
 261         return timer->_softexpires.tv64;
 262 }
 263
 264 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
 265 {
 266         return ktime_to_ns(timer->node.expires);
 267 }
 268
 269 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
 270 {
 271         return ktime_sub(timer->node.expires, timer->base->get_time());
 272 }
 273
 274 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 275 {
 276         return timer->base->get_time();
 277 }
 278
 279 #ifdef CONFIG_HIGH_RES_TIMERS
 280 struct clock_event_device;
 281
 282 extern void hrtimer_interrupt(struct clock_event_device *dev);
 283
 284 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 285 {
 286         return timer->base->cpu_base->hres_active;
 287 }
 288
 289 extern void hrtimer_peek_ahead_timers(void);
 290
 291 /*
 292  * The resolution of the clocks. The resolution value is returned in
 293  * the clock_getres() system call to give application programmers an
 294  * idea of the (in)accuracy of timers. Timer values are rounded up to
 295  * this resolution values.
 296  */
 297 # define HIGH_RES_NSEC          1
 298 # define KTIME_HIGH_RES         (ktime_t) { .tv64 = HIGH_RES_NSEC }
 299 # define MONOTONIC_RES_NSEC     HIGH_RES_NSEC
 300 # define KTIME_MONOTONIC_RES    KTIME_HIGH_RES
 301
 302 extern void clock_was_set_delayed(void);
 303
 304 extern unsigned int hrtimer_resolution;
 305
 306 #else
 307
 308 # define MONOTONIC_RES_NSEC     LOW_RES_NSEC
 309 # define KTIME_MONOTONIC_RES    KTIME_LOW_RES
 310
 311 #define hrtimer_resolution      (unsigned int)LOW_RES_NSEC
 312
 313 static inline void hrtimer_peek_ahead_timers(void) { }
 314
 315 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 316 {
 317         return 0;
 318 }
 319
 320 static inline void clock_was_set_delayed(void) { }
 321
 322 #endif
 323
 324 extern void clock_was_set(void);
 325 #ifdef CONFIG_TIMERFD
 326 extern void timerfd_clock_was_set(void);
 327 #else
 328 static inline void timerfd_clock_was_set(void) { }
 329 #endif
 330 extern void hrtimers_resume(void);
 331
 332 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
 333
 334
 335 /* Exported timer functions: */
 336
 337 /* Initialize timers: */
 338 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 339                          enum hrtimer_mode mode);
 340
 341 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 342 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
 343                                   enum hrtimer_mode mode);
 344
 345 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
 346 #else
 347 static 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 }
 353 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
 354 #endif
 355
 356 /* Basic timer operations: */
 357 extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 358                         unsigned long range_ns, const enum hrtimer_mode mode);
 359
 360 /**
 361  * hrtimer_start - (re)start an hrtimer on the current CPU
 362  * @timer:      the timer to be added
 363  * @tim:        expiry time
 364  * @mode:       expiry mode: absolute (HRTIMER_MODE_ABS) or
 365  *              relative (HRTIMER_MODE_REL)
 366  */
 367 static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
 368                                  const enum hrtimer_mode mode)
 369 {
 370         hrtimer_start_range_ns(timer, tim, 0, mode);
 371 }
 372
 373 extern int hrtimer_cancel(struct hrtimer *timer);
 374 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 375
 376 static inline void hrtimer_start_expires(struct hrtimer *timer,
 377                                          enum hrtimer_mode mode)
 378 {
 379         unsigned long delta;
 380         ktime_t soft, hard;
 381         soft = hrtimer_get_softexpires(timer);
 382         hard = hrtimer_get_expires(timer);
 383         delta = ktime_to_ns(ktime_sub(hard, soft));
 384         hrtimer_start_range_ns(timer, soft, delta, mode);
 385 }
 386
 387 static inline void hrtimer_restart(struct hrtimer *timer)
 388 {
 389         hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 390 }
 391
 392 /* Query timers: */
 393 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 394
 395 extern u64 hrtimer_get_next_event(void);
 396
 397 extern bool hrtimer_active(const struct hrtimer *timer);
 398
 399 /*
 400  * Helper function to check, whether the timer is on one of the queues
 401  */
 402 static inline int hrtimer_is_queued(struct hrtimer *timer)
 403 {
 404         return timer->state & HRTIMER_STATE_ENQUEUED;
 405 }
 406
 407 /*
 408  * Helper function to check, whether the timer is running the callback
 409  * function
 410  */
 411 static inline int hrtimer_callback_running(struct hrtimer *timer)
 412 {
 413         return timer->base->cpu_base->running == timer;
 414 }
 415
 416 /* Forward a hrtimer so it expires after now: */
 417 extern u64
 418 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 419
 420 /**
 421  * hrtimer_forward_now - forward the timer expiry so it expires after now
 422  * @timer:      hrtimer to forward
 423  * @interval:   the interval to forward
 424  *
 425  * Forward the timer expiry so it will expire after the current time
 426  * of the hrtimer clock base. Returns the number of overruns.
 427  *
 428  * Can be safely called from the callback function of @timer. If
 429  * called from other contexts @timer must neither be enqueued nor
 430  * running the callback and the caller needs to take care of
 431  * serialization.
 432  *
 433  * Note: This only updates the timer expiry value and does not requeue
 434  * the timer.
 435  */
 436 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 437                                       ktime_t interval)
 438 {
 439         return hrtimer_forward(timer, timer->base->get_time(), interval);
 440 }
 441
 442 /* Precise sleep: */
 443 extern long hrtimer_nanosleep(struct timespec *rqtp,
 444                               struct timespec __user *rmtp,
 445                               const enum hrtimer_mode mode,
 446                               const clockid_t clockid);
 447 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
 448
 449 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 450                                  struct task_struct *tsk);
 451
 452 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
 453                                                 const enum hrtimer_mode mode);
 454 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
 455                 unsigned long delta, const enum hrtimer_mode mode, int clock);
 456 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
 457
 458 /* Soft interrupt function to run the hrtimer queues: */
 459 extern void hrtimer_run_queues(void);
 460
 461 /* Bootup initialization: */
 462 extern void __init hrtimers_init(void);
 463
 464 /* Show pending timers: */
 465 extern void sysrq_timer_list_show(void);
 466
 467 #endif