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.
  74  *
  75  * All state transitions are protected by cpu_base->lock.
  76  */
  77 #define HRTIMER_STATE_INACTIVE  0x00
  78 #define HRTIMER_STATE_ENQUEUED  0x01
  79 #define HRTIMER_STATE_CALLBACK  0x02
  80
  81 /**
  82  * struct hrtimer - the basic hrtimer structure
  83  * @node:       timerqueue node, which also manages node.expires,
  84  *              the absolute expiry time in the hrtimers internal
  85  *              representation. The time is related to the clock on
  86  *              which the timer is based. Is setup by adding
  87  *              slack to the _softexpires value. For non range timers
  88  *              identical to _softexpires.
  89  * @_softexpires: the absolute earliest expiry time of the hrtimer.
  90  *              The time which was given as expiry time when the timer
  91  *              was armed.
  92  * @function:   timer expiry callback function
  93  * @base:       pointer to the timer base (per cpu and per clock)
  94  * @state:      state information (See bit values above)
  95  * @start_pid: timer statistics field to store the pid of the task which
  96  *              started the timer
  97  * @start_site: timer statistics field to store the site where the timer
  98  *              was started
  99  * @start_comm: timer statistics field to store the name of the process which
 100  *              started the timer
 101  *
 102  * The hrtimer structure must be initialized by hrtimer_init()
 103  */
 104 struct hrtimer {
 105         struct timerqueue_node          node;
 106         ktime_t                         _softexpires;
 107         enum hrtimer_restart            (*function)(struct hrtimer *);
 108         struct hrtimer_clock_base       *base;
 109         unsigned long                   state;
 110 #ifdef CONFIG_TIMER_STATS
 111         int                             start_pid;
 112         void                            *start_site;
 113         char                            start_comm[16];
 114 #endif
 115 };
 116
 117 /**
 118  * struct hrtimer_sleeper - simple sleeper structure
 119  * @timer:      embedded timer structure
 120  * @task:       task to wake up
 121  *
 122  * task is set to NULL, when the timer expires.
 123  */
 124 struct hrtimer_sleeper {
 125         struct hrtimer timer;
 126         struct task_struct *task;
 127 };
 128
 129 #ifdef CONFIG_64BIT
 130 # define HRTIMER_CLOCK_BASE_ALIGN       64
 131 #else
 132 # define HRTIMER_CLOCK_BASE_ALIGN       32
 133 #endif
 134
 135 /**
 136  * struct hrtimer_clock_base - the timer base for a specific clock
 137  * @cpu_base:           per cpu clock base
 138  * @index:              clock type index for per_cpu support when moving a
 139  *                      timer to a base on another cpu.
 140  * @clockid:            clock id for per_cpu support
 141  * @active:             red black tree root node for the active timers
 142  * @get_time:           function to retrieve the current time of the clock
 143  * @offset:             offset of this clock to the monotonic base
 144  */
 145 struct 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                 (*get_time)(void);
 151         ktime_t                 offset;
 152 } __attribute__((__aligned__(HRTIMER_CLOCK_BASE_ALIGN)));
 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_seq:  Sequence counter of clock was set events
 169  * @expires_next:       absolute time of the next event which was scheduled
 170  *                      via clock_set_next_event()
 171  * @next_timer:         Pointer to the first expiring timer
 172  * @in_hrtirq:          hrtimer_interrupt() is currently executing
 173  * @hres_active:        State of high resolution mode
 174  * @hang_detected:      The last hrtimer interrupt detected a hang
 175  * @nr_events:          Total number of hrtimer interrupt events
 176  * @nr_retries:         Total number of hrtimer interrupt retries
 177  * @nr_hangs:           Total number of hrtimer interrupt hangs
 178  * @max_hang_time:      Maximum time spent in hrtimer_interrupt
 179  * @clock_base:         array of clock bases for this cpu
 180  *
 181  * Note: next_timer is just an optimization for __remove_hrtimer().
 182  *       Do not dereference the pointer because it is not reliable on
 183  *       cross cpu removals.
 184  */
 185 struct hrtimer_cpu_base {
 186         raw_spinlock_t                  lock;
 187         unsigned int                    cpu;
 188         unsigned int                    active_bases;
 189         unsigned int                    clock_was_set_seq;
 190 #ifdef CONFIG_HIGH_RES_TIMERS
 191         unsigned int                    in_hrtirq       : 1,
 192                                         hres_active     : 1,
 193                                         hang_detected   : 1;
 194         ktime_t                         expires_next;
 195         struct hrtimer                  *next_timer;
 196         unsigned int                    nr_events;
 197         unsigned int                    nr_retries;
 198         unsigned int                    nr_hangs;
 199         unsigned int                    max_hang_time;
 200 #endif
 201         struct hrtimer_clock_base       clock_base[HRTIMER_MAX_CLOCK_BASES];
 202 } ____cacheline_aligned;
 203
 204 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
 205 {
 206         BUILD_BUG_ON(sizeof(struct hrtimer_clock_base) > HRTIMER_CLOCK_BASE_ALIGN);
 207
 208         timer->node.expires = time;
 209         timer->_softexpires = time;
 210 }
 211
 212 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
 213 {
 214         timer->_softexpires = time;
 215         timer->node.expires = ktime_add_safe(time, delta);
 216 }
 217
 218 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
 219 {
 220         timer->_softexpires = time;
 221         timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
 222 }
 223
 224 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
 225 {
 226         timer->node.expires.tv64 = tv64;
 227         timer->_softexpires.tv64 = tv64;
 228 }
 229
 230 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
 231 {
 232         timer->node.expires = ktime_add_safe(timer->node.expires, time);
 233         timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
 234 }
 235
 236 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
 237 {
 238         timer->node.expires = ktime_add_ns(timer->node.expires, ns);
 239         timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
 240 }
 241
 242 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
 243 {
 244         return timer->node.expires;
 245 }
 246
 247 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
 248 {
 249         return timer->_softexpires;
 250 }
 251
 252 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
 253 {
 254         return timer->node.expires.tv64;
 255 }
 256 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
 257 {
 258         return timer->_softexpires.tv64;
 259 }
 260
 261 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
 262 {
 263         return ktime_to_ns(timer->node.expires);
 264 }
 265
 266 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
 267 {
 268         return ktime_sub(timer->node.expires, timer->base->get_time());
 269 }
 270
 271 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 272 {
 273         return timer->base->get_time();
 274 }
 275
 276 #ifdef CONFIG_HIGH_RES_TIMERS
 277 struct clock_event_device;
 278
 279 extern void hrtimer_interrupt(struct clock_event_device *dev);
 280
 281 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 282 {
 283         return timer->base->cpu_base->hres_active;
 284 }
 285
 286 extern void hrtimer_peek_ahead_timers(void);
 287
 288 /*
 289  * The resolution of the clocks. The resolution value is returned in
 290  * the clock_getres() system call to give application programmers an
 291  * idea of the (in)accuracy of timers. Timer values are rounded up to
 292  * this resolution values.
 293  */
 294 # define HIGH_RES_NSEC          1
 295 # define KTIME_HIGH_RES         (ktime_t) { .tv64 = HIGH_RES_NSEC }
 296 # define MONOTONIC_RES_NSEC     HIGH_RES_NSEC
 297 # define KTIME_MONOTONIC_RES    KTIME_HIGH_RES
 298
 299 extern void clock_was_set_delayed(void);
 300
 301 extern unsigned int hrtimer_resolution;
 302
 303 #else
 304
 305 # define MONOTONIC_RES_NSEC     LOW_RES_NSEC
 306 # define KTIME_MONOTONIC_RES    KTIME_LOW_RES
 307
 308 #define hrtimer_resolution      (unsigned int)LOW_RES_NSEC
 309
 310 static inline void hrtimer_peek_ahead_timers(void) { }
 311
 312 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 313 {
 314         return 0;
 315 }
 316
 317 static inline void clock_was_set_delayed(void) { }
 318
 319 #endif
 320
 321 extern void clock_was_set(void);
 322 #ifdef CONFIG_TIMERFD
 323 extern void timerfd_clock_was_set(void);
 324 #else
 325 static inline void timerfd_clock_was_set(void) { }
 326 #endif
 327 extern void hrtimers_resume(void);
 328
 329 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
 330
 331
 332 /* Exported timer functions: */
 333
 334 /* Initialize timers: */
 335 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 336                          enum hrtimer_mode mode);
 337
 338 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 339 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
 340                                   enum hrtimer_mode mode);
 341
 342 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
 343 #else
 344 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
 345                                          clockid_t which_clock,
 346                                          enum hrtimer_mode mode)
 347 {
 348         hrtimer_init(timer, which_clock, mode);
 349 }
 350 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
 351 #endif
 352
 353 /* Basic timer operations: */
 354 extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 355                         unsigned long range_ns, const enum hrtimer_mode mode);
 356
 357 /**
 358  * hrtimer_start - (re)start an hrtimer on the current CPU
 359  * @timer:      the timer to be added
 360  * @tim:        expiry time
 361  * @mode:       expiry mode: absolute (HRTIMER_MODE_ABS) or
 362  *              relative (HRTIMER_MODE_REL)
 363  */
 364 static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
 365                                  const enum hrtimer_mode mode)
 366 {
 367         hrtimer_start_range_ns(timer, tim, 0, mode);
 368 }
 369
 370 extern int hrtimer_cancel(struct hrtimer *timer);
 371 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 372
 373 static inline void hrtimer_start_expires(struct hrtimer *timer,
 374                                          enum hrtimer_mode mode)
 375 {
 376         unsigned long delta;
 377         ktime_t soft, hard;
 378         soft = hrtimer_get_softexpires(timer);
 379         hard = hrtimer_get_expires(timer);
 380         delta = ktime_to_ns(ktime_sub(hard, soft));
 381         hrtimer_start_range_ns(timer, soft, delta, mode);
 382 }
 383
 384 static inline void hrtimer_restart(struct hrtimer *timer)
 385 {
 386         hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 387 }
 388
 389 /* Query timers: */
 390 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 391
 392 extern u64 hrtimer_get_next_event(void);
 393
 394 /*
 395  * A timer is active, when it is enqueued into the rbtree or the
 396  * callback function is running or it's in the state of being migrated
 397  * to another cpu.
 398  */
 399 static inline int hrtimer_active(const struct hrtimer *timer)
 400 {
 401         return timer->state != HRTIMER_STATE_INACTIVE;
 402 }
 403
 404 /*
 405  * Helper function to check, whether the timer is on one of the queues
 406  */
 407 static inline int hrtimer_is_queued(struct hrtimer *timer)
 408 {
 409         return timer->state & HRTIMER_STATE_ENQUEUED;
 410 }
 411
 412 /*
 413  * Helper function to check, whether the timer is running the callback
 414  * function
 415  */
 416 static inline int hrtimer_callback_running(struct hrtimer *timer)
 417 {
 418         return timer->state & HRTIMER_STATE_CALLBACK;
 419 }
 420
 421 /* Forward a hrtimer so it expires after now: */
 422 extern u64
 423 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 424
 425 /**
 426  * hrtimer_forward_now - forward the timer expiry so it expires after now
 427  * @timer:      hrtimer to forward
 428  * @interval:   the interval to forward
 429  *
 430  * Forward the timer expiry so it will expire after the current time
 431  * of the hrtimer clock base. Returns the number of overruns.
 432  *
 433  * Can be safely called from the callback function of @timer. If
 434  * called from other contexts @timer must neither be enqueued nor
 435  * running the callback and the caller needs to take care of
 436  * serialization.
 437  *
 438  * Note: This only updates the timer expiry value and does not requeue
 439  * the timer.
 440  */
 441 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 442                                       ktime_t interval)
 443 {
 444         return hrtimer_forward(timer, timer->base->get_time(), interval);
 445 }
 446
 447 /* Precise sleep: */
 448 extern long hrtimer_nanosleep(struct timespec *rqtp,
 449                               struct timespec __user *rmtp,
 450                               const enum hrtimer_mode mode,
 451                               const clockid_t clockid);
 452 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
 453
 454 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 455                                  struct task_struct *tsk);
 456
 457 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
 458                                                 const enum hrtimer_mode mode);
 459 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
 460                 unsigned long delta, const enum hrtimer_mode mode, int clock);
 461 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
 462
 463 /* Soft interrupt function to run the hrtimer queues: */
 464 extern void hrtimer_run_queues(void);
 465
 466 /* Bootup initialization: */
 467 extern void __init hrtimers_init(void);
 468
 469 /* Show pending timers: */
 470 extern void sysrq_timer_list_show(void);
 471
 472 #endif