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 #ifdef CONFIG_64BIT
 134 # define HRTIMER_CLOCK_BASE_ALIGN       64
 135 #else
 136 # define HRTIMER_CLOCK_BASE_ALIGN       32
 137 #endif
 138
 139 /**
 140  * struct hrtimer_clock_base - the timer base for a specific clock
 141  * @cpu_base:           per cpu clock base
 142  * @index:              clock type index for per_cpu support when moving a
 143  *                      timer to a base on another cpu.
 144  * @clockid:            clock id for per_cpu support
 145  * @active:             red black tree root node for the active timers
 146  * @get_time:           function to retrieve the current time of the clock
 147  * @offset:             offset of this clock to the monotonic base
 148  */
 149 struct hrtimer_clock_base {
 150         struct hrtimer_cpu_base *cpu_base;
 151         int                     index;
 152         clockid_t               clockid;
 153         struct timerqueue_head  active;
 154         ktime_t                 (*get_time)(void);
 155         ktime_t                 offset;
 156 } __attribute__((__aligned__(HRTIMER_CLOCK_BASE_ALIGN)));
 157
 158 enum  hrtimer_base_type {
 159         HRTIMER_BASE_MONOTONIC,
 160         HRTIMER_BASE_REALTIME,
 161         HRTIMER_BASE_BOOTTIME,
 162         HRTIMER_BASE_TAI,
 163         HRTIMER_MAX_CLOCK_BASES,
 164 };
 165
 166 /*
 167  * struct hrtimer_cpu_base - the per cpu clock bases
 168  * @lock:               lock protecting the base and associated clock bases
 169  *                      and timers
 170  * @cpu:                cpu number
 171  * @active_bases:       Bitfield to mark bases with active timers
 172  * @clock_was_set_seq:  Sequence counter of clock was set events
 173  * @expires_next:       absolute time of the next event which was scheduled
 174  *                      via clock_set_next_event()
 175  * @next_timer:         Pointer to the first expiring timer
 176  * @in_hrtirq:          hrtimer_interrupt() is currently executing
 177  * @hres_active:        State of high resolution mode
 178  * @hang_detected:      The last hrtimer interrupt detected a hang
 179  * @nr_events:          Total number of hrtimer interrupt events
 180  * @nr_retries:         Total number of hrtimer interrupt retries
 181  * @nr_hangs:           Total number of hrtimer interrupt hangs
 182  * @max_hang_time:      Maximum time spent in hrtimer_interrupt
 183  * @clock_base:         array of clock bases for this cpu
 184  *
 185  * Note: next_timer is just an optimization for __remove_hrtimer().
 186  *       Do not dereference the pointer because it is not reliable on
 187  *       cross cpu removals.
 188  */
 189 struct hrtimer_cpu_base {
 190         raw_spinlock_t                  lock;
 191         unsigned int                    cpu;
 192         unsigned int                    active_bases;
 193         unsigned int                    clock_was_set_seq;
 194 #ifdef CONFIG_HIGH_RES_TIMERS
 195         unsigned int                    in_hrtirq       : 1,
 196                                         hres_active     : 1,
 197                                         hang_detected   : 1;
 198         ktime_t                         expires_next;
 199         struct hrtimer                  *next_timer;
 200         unsigned int                    nr_events;
 201         unsigned int                    nr_retries;
 202         unsigned int                    nr_hangs;
 203         unsigned int                    max_hang_time;
 204 #endif
 205         struct hrtimer_clock_base       clock_base[HRTIMER_MAX_CLOCK_BASES];
 206 } ____cacheline_aligned;
 207
 208 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
 209 {
 210         BUILD_BUG_ON(sizeof(struct hrtimer_clock_base) > HRTIMER_CLOCK_BASE_ALIGN);
 211
 212         timer->node.expires = time;
 213         timer->_softexpires = time;
 214 }
 215
 216 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
 217 {
 218         timer->_softexpires = time;
 219         timer->node.expires = ktime_add_safe(time, delta);
 220 }
 221
 222 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
 223 {
 224         timer->_softexpires = time;
 225         timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
 226 }
 227
 228 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
 229 {
 230         timer->node.expires.tv64 = tv64;
 231         timer->_softexpires.tv64 = tv64;
 232 }
 233
 234 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
 235 {
 236         timer->node.expires = ktime_add_safe(timer->node.expires, time);
 237         timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
 238 }
 239
 240 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
 241 {
 242         timer->node.expires = ktime_add_ns(timer->node.expires, ns);
 243         timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
 244 }
 245
 246 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
 247 {
 248         return timer->node.expires;
 249 }
 250
 251 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
 252 {
 253         return timer->_softexpires;
 254 }
 255
 256 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
 257 {
 258         return timer->node.expires.tv64;
 259 }
 260 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
 261 {
 262         return timer->_softexpires.tv64;
 263 }
 264
 265 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
 266 {
 267         return ktime_to_ns(timer->node.expires);
 268 }
 269
 270 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
 271 {
 272         return ktime_sub(timer->node.expires, timer->base->get_time());
 273 }
 274
 275 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 276 {
 277         return timer->base->get_time();
 278 }
 279
 280 #ifdef CONFIG_HIGH_RES_TIMERS
 281 struct clock_event_device;
 282
 283 extern void hrtimer_interrupt(struct clock_event_device *dev);
 284
 285 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 286 {
 287         return timer->base->cpu_base->hres_active;
 288 }
 289
 290 extern void hrtimer_peek_ahead_timers(void);
 291
 292 /*
 293  * The resolution of the clocks. The resolution value is returned in
 294  * the clock_getres() system call to give application programmers an
 295  * idea of the (in)accuracy of timers. Timer values are rounded up to
 296  * this resolution values.
 297  */
 298 # define HIGH_RES_NSEC          1
 299 # define KTIME_HIGH_RES         (ktime_t) { .tv64 = HIGH_RES_NSEC }
 300 # define MONOTONIC_RES_NSEC     HIGH_RES_NSEC
 301 # define KTIME_MONOTONIC_RES    KTIME_HIGH_RES
 302
 303 extern void clock_was_set_delayed(void);
 304
 305 extern unsigned int hrtimer_resolution;
 306
 307 #else
 308
 309 # define MONOTONIC_RES_NSEC     LOW_RES_NSEC
 310 # define KTIME_MONOTONIC_RES    KTIME_LOW_RES
 311
 312 #define hrtimer_resolution      LOW_RES_NSEC
 313
 314 static inline void hrtimer_peek_ahead_timers(void) { }
 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
 363 extern int hrtimer_cancel(struct hrtimer *timer);
 364 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 365
 366 static inline int hrtimer_start_expires(struct hrtimer *timer,
 367                                                 enum hrtimer_mode mode)
 368 {
 369         unsigned long delta;
 370         ktime_t soft, hard;
 371         soft = hrtimer_get_softexpires(timer);
 372         hard = hrtimer_get_expires(timer);
 373         delta = ktime_to_ns(ktime_sub(hard, soft));
 374         return hrtimer_start_range_ns(timer, soft, delta, mode);
 375 }
 376
 377 static inline int hrtimer_restart(struct hrtimer *timer)
 378 {
 379         return hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 380 }
 381
 382 /* Query timers: */
 383 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
 384
 385 extern u64 hrtimer_get_next_event(void);
 386
 387 /*
 388  * A timer is active, when it is enqueued into the rbtree or the
 389  * callback function is running or it's in the state of being migrated
 390  * to another cpu.
 391  */
 392 static inline int hrtimer_active(const struct hrtimer *timer)
 393 {
 394         return timer->state != HRTIMER_STATE_INACTIVE;
 395 }
 396
 397 /*
 398  * Helper function to check, whether the timer is on one of the queues
 399  */
 400 static inline int hrtimer_is_queued(struct hrtimer *timer)
 401 {
 402         return timer->state & HRTIMER_STATE_ENQUEUED;
 403 }
 404
 405 /*
 406  * Helper function to check, whether the timer is running the callback
 407  * function
 408  */
 409 static inline int hrtimer_callback_running(struct hrtimer *timer)
 410 {
 411         return timer->state & HRTIMER_STATE_CALLBACK;
 412 }
 413
 414 /* Forward a hrtimer so it expires after now: */
 415 extern u64
 416 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 417
 418 /**
 419  * hrtimer_forward_now - forward the timer expiry so it expires after now
 420  * @timer:      hrtimer to forward
 421  * @interval:   the interval to forward
 422  *
 423  * Forward the timer expiry so it will expire after the current time
 424  * of the hrtimer clock base. Returns the number of overruns.
 425  *
 426  * Can be safely called from the callback function of @timer. If
 427  * called from other contexts @timer must neither be enqueued nor
 428  * running the callback and the caller needs to take care of
 429  * serialization.
 430  *
 431  * Note: This only updates the timer expiry value and does not requeue
 432  * the timer.
 433  */
 434 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 435                                       ktime_t interval)
 436 {
 437         return hrtimer_forward(timer, timer->base->get_time(), interval);
 438 }
 439
 440 /* Precise sleep: */
 441 extern long hrtimer_nanosleep(struct timespec *rqtp,
 442                               struct timespec __user *rmtp,
 443                               const enum hrtimer_mode mode,
 444                               const clockid_t clockid);
 445 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
 446
 447 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 448                                  struct task_struct *tsk);
 449
 450 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
 451                                                 const enum hrtimer_mode mode);
 452 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
 453                 unsigned long delta, const enum hrtimer_mode mode, int clock);
 454 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
 455
 456 /* Soft interrupt function to run the hrtimer queues: */
 457 extern void hrtimer_run_queues(void);
 458
 459 /* Bootup initialization: */
 460 extern void __init hrtimers_init(void);
 461
 462 /* Show pending timers: */
 463 extern void sysrq_timer_list_show(void);
 464
 465 #endif