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  * @is_rel:     Set if the timer was armed relative
  91  * @start_pid:  timer statistics field to store the pid of the task which
  92  *              started the timer
  93  * @start_site: timer statistics field to store the site where the timer
  94  *              was started
  95  * @start_comm: timer statistics field to store the name of the process which
  96  *              started the timer
  97  *
  98  * The hrtimer structure must be initialized by hrtimer_init()
  99  */
 100 struct hrtimer {
 101         struct timerqueue_node          node;
 102         ktime_t                         _softexpires;
 103         enum hrtimer_restart            (*function)(struct hrtimer *);
 104         struct hrtimer_clock_base       *base;
 105         u8                              state;
 106         u8                              is_rel;
 107 #ifdef CONFIG_TIMER_STATS
 108         int                             start_pid;
 109         void                            *start_site;
 110         char                            start_comm[16];
 111 #endif
 112 };
 113
 114 /**
 115  * struct hrtimer_sleeper - simple sleeper structure
 116  * @timer:      embedded timer structure
 117  * @task:       task to wake up
 118  *
 119  * task is set to NULL, when the timer expires.
 120  */
 121 struct hrtimer_sleeper {
 122         struct hrtimer timer;
 123         struct task_struct *task;
 124 };
 125
 126 #ifdef CONFIG_64BIT
 127 # define HRTIMER_CLOCK_BASE_ALIGN       64
 128 #else
 129 # define HRTIMER_CLOCK_BASE_ALIGN       32
 130 #endif
 131
 132 /**
 133  * struct hrtimer_clock_base - the timer base for a specific clock
 134  * @cpu_base:           per cpu clock base
 135  * @index:              clock type index for per_cpu support when moving a
 136  *                      timer to a base on another cpu.
 137  * @clockid:            clock id for per_cpu support
 138  * @active:             red black tree root node for the active timers
 139  * @get_time:           function to retrieve the current time of the clock
 140  * @offset:             offset of this clock to the monotonic base
 141  */
 142 struct hrtimer_clock_base {
 143         struct hrtimer_cpu_base *cpu_base;
 144         int                     index;
 145         clockid_t               clockid;
 146         struct timerqueue_head  active;
 147         ktime_t                 (*get_time)(void);
 148         ktime_t                 offset;
 149 } __attribute__((__aligned__(HRTIMER_CLOCK_BASE_ALIGN)));
 150
 151 enum  hrtimer_base_type {
 152         HRTIMER_BASE_MONOTONIC,
 153         HRTIMER_BASE_REALTIME,
 154         HRTIMER_BASE_BOOTTIME,
 155         HRTIMER_BASE_TAI,
 156         HRTIMER_MAX_CLOCK_BASES,
 157 };
 158
 159 /*
 160  * struct hrtimer_cpu_base - the per cpu clock bases
 161  * @lock:               lock protecting the base and associated clock bases
 162  *                      and timers
 163  * @seq:                seqcount around __run_hrtimer
 164  * @running:            pointer to the currently running hrtimer
 165  * @cpu:                cpu number
 166  * @active_bases:       Bitfield to mark bases with active timers
 167  * @clock_was_set_seq:  Sequence counter of clock was set events
 168  * @migration_enabled:  The migration of hrtimers to other cpus is enabled
 169  * @nohz_active:        The nohz functionality is enabled
 170  * @expires_next:       absolute time of the next event which was scheduled
 171  *                      via clock_set_next_event()
 172  * @next_timer:         Pointer to the first expiring timer
 173  * @in_hrtirq:          hrtimer_interrupt() is currently executing
 174  * @hres_active:        State of high resolution mode
 175  * @hang_detected:      The last hrtimer interrupt detected a hang
 176  * @nr_events:          Total number of hrtimer interrupt events
 177  * @nr_retries:         Total number of hrtimer interrupt retries
 178  * @nr_hangs:           Total number of hrtimer interrupt hangs
 179  * @max_hang_time:      Maximum time spent in hrtimer_interrupt
 180  * @clock_base:         array of clock bases for this cpu
 181  *
 182  * Note: next_timer is just an optimization for __remove_hrtimer().
 183  *       Do not dereference the pointer because it is not reliable on
 184  *       cross cpu removals.
 185  */
 186 struct hrtimer_cpu_base {
 187         raw_spinlock_t                  lock;
 188         seqcount_t                      seq;
 189         struct hrtimer                  *running;
 190         unsigned int                    cpu;
 191         unsigned int                    active_bases;
 192         unsigned int                    clock_was_set_seq;
 193         bool                            migration_enabled;
 194         bool                            nohz_active;
 195 #ifdef CONFIG_HIGH_RES_TIMERS
 196         unsigned int                    in_hrtirq       : 1,
 197                                         hres_active     : 1,
 198                                         hang_detected   : 1;
 199         ktime_t                         expires_next;
 200         struct hrtimer                  *next_timer;
 201         unsigned int                    nr_events;
 202         unsigned int                    nr_retries;
 203         unsigned int                    nr_hangs;
 204         unsigned int                    max_hang_time;
 205 #endif
 206         struct hrtimer_clock_base       clock_base[HRTIMER_MAX_CLOCK_BASES];
 207 } ____cacheline_aligned;
 208
 209 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
 210 {
 211         BUILD_BUG_ON(sizeof(struct hrtimer_clock_base) > HRTIMER_CLOCK_BASE_ALIGN);
 212
 213         timer->node.expires = time;
 214         timer->_softexpires = time;
 215 }
 216
 217 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
 218 {
 219         timer->_softexpires = time;
 220         timer->node.expires = ktime_add_safe(time, delta);
 221 }
 222
 223 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, u64 delta)
 224 {
 225         timer->_softexpires = time;
 226         timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
 227 }
 228
 229 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
 230 {
 231         timer->node.expires.tv64 = tv64;
 232         timer->_softexpires.tv64 = tv64;
 233 }
 234
 235 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
 236 {
 237         timer->node.expires = ktime_add_safe(timer->node.expires, time);
 238         timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
 239 }
 240
 241 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
 242 {
 243         timer->node.expires = ktime_add_ns(timer->node.expires, ns);
 244         timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
 245 }
 246
 247 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
 248 {
 249         return timer->node.expires;
 250 }
 251
 252 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
 253 {
 254         return timer->_softexpires;
 255 }
 256
 257 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
 258 {
 259         return timer->node.expires.tv64;
 260 }
 261 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
 262 {
 263         return timer->_softexpires.tv64;
 264 }
 265
 266 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
 267 {
 268         return ktime_to_ns(timer->node.expires);
 269 }
 270
 271 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
 272 {
 273         return ktime_sub(timer->node.expires, timer->base->get_time());
 274 }
 275
 276 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 277 {
 278         return timer->base->get_time();
 279 }
 280
 281 #ifdef CONFIG_HIGH_RES_TIMERS
 282 struct clock_event_device;
 283
 284 extern void hrtimer_interrupt(struct clock_event_device *dev);
 285
 286 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 287 {
 288         return timer->base->cpu_base->hres_active;
 289 }
 290
 291 extern void hrtimer_peek_ahead_timers(void);
 292
 293 /*
 294  * The resolution of the clocks. The resolution value is returned in
 295  * the clock_getres() system call to give application programmers an
 296  * idea of the (in)accuracy of timers. Timer values are rounded up to
 297  * this resolution values.
 298  */
 299 # define HIGH_RES_NSEC          1
 300 # define KTIME_HIGH_RES         (ktime_t) { .tv64 = HIGH_RES_NSEC }
 301 # define MONOTONIC_RES_NSEC     HIGH_RES_NSEC
 302 # define KTIME_MONOTONIC_RES    KTIME_HIGH_RES
 303
 304 extern void clock_was_set_delayed(void);
 305
 306 extern unsigned int hrtimer_resolution;
 307
 308 #else
 309
 310 # define MONOTONIC_RES_NSEC     LOW_RES_NSEC
 311 # define KTIME_MONOTONIC_RES    KTIME_LOW_RES
 312
 313 #define hrtimer_resolution      (unsigned int)LOW_RES_NSEC
 314
 315 static inline void hrtimer_peek_ahead_timers(void) { }
 316
 317 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 318 {
 319         return 0;
 320 }
 321
 322 static inline void clock_was_set_delayed(void) { }
 323
 324 #endif
 325
 326 static inline ktime_t
 327 __hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now)
 328 {
 329         ktime_t rem = ktime_sub(timer->node.expires, now);
 330
 331         /*
 332          * Adjust relative timers for the extra we added in
 333          * hrtimer_start_range_ns() to prevent short timeouts.
 334          */
 335         if (IS_ENABLED(CONFIG_TIME_LOW_RES) && timer->is_rel)
 336                 rem.tv64 -= hrtimer_resolution;
 337         return rem;
 338 }
 339
 340 static inline ktime_t
 341 hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
 342 {
 343         return __hrtimer_expires_remaining_adjusted(timer,
 344                                                     timer->base->get_time());
 345 }
 346
 347 extern void clock_was_set(void);
 348 #ifdef CONFIG_TIMERFD
 349 extern void timerfd_clock_was_set(void);
 350 #else
 351 static inline void timerfd_clock_was_set(void) { }
 352 #endif
 353 extern void hrtimers_resume(void);
 354
 355 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
 356
 357
 358 /* Exported timer functions: */
 359
 360 /* Initialize timers: */
 361 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 362                          enum hrtimer_mode mode);
 363
 364 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 365 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
 366                                   enum hrtimer_mode mode);
 367
 368 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
 369 #else
 370 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
 371                                          clockid_t which_clock,
 372                                          enum hrtimer_mode mode)
 373 {
 374         hrtimer_init(timer, which_clock, mode);
 375 }
 376 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
 377 #endif
 378
 379 /* Basic timer operations: */
 380 extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 381                                    u64 range_ns, const enum hrtimer_mode mode);
 382
 383 /**
 384  * hrtimer_start - (re)start an hrtimer on the current CPU
 385  * @timer:      the timer to be added
 386  * @tim:        expiry time
 387  * @mode:       expiry mode: absolute (HRTIMER_MODE_ABS) or
 388  *              relative (HRTIMER_MODE_REL)
 389  */
 390 static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
 391                                  const enum hrtimer_mode mode)
 392 {
 393         hrtimer_start_range_ns(timer, tim, 0, mode);
 394 }
 395
 396 extern int hrtimer_cancel(struct hrtimer *timer);
 397 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 398
 399 static inline void hrtimer_start_expires(struct hrtimer *timer,
 400                                          enum hrtimer_mode mode)
 401 {
 402         u64 delta;
 403         ktime_t soft, hard;
 404         soft = hrtimer_get_softexpires(timer);
 405         hard = hrtimer_get_expires(timer);
 406         delta = ktime_to_ns(ktime_sub(hard, soft));
 407         hrtimer_start_range_ns(timer, soft, delta, mode);
 408 }
 409
 410 static inline void hrtimer_restart(struct hrtimer *timer)
 411 {
 412         hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 413 }
 414
 415 /* Query timers: */
 416 extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);
 417
 418 static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
 419 {
 420         return __hrtimer_get_remaining(timer, false);
 421 }
 422
 423 extern u64 hrtimer_get_next_event(void);
 424
 425 extern bool hrtimer_active(const struct hrtimer *timer);
 426
 427 /*
 428  * Helper function to check, whether the timer is on one of the queues
 429  */
 430 static inline int hrtimer_is_queued(struct hrtimer *timer)
 431 {
 432         return timer->state & HRTIMER_STATE_ENQUEUED;
 433 }
 434
 435 /*
 436  * Helper function to check, whether the timer is running the callback
 437  * function
 438  */
 439 static inline int hrtimer_callback_running(struct hrtimer *timer)
 440 {
 441         return timer->base->cpu_base->running == timer;
 442 }
 443
 444 /* Forward a hrtimer so it expires after now: */
 445 extern u64
 446 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 447
 448 /**
 449  * hrtimer_forward_now - forward the timer expiry so it expires after now
 450  * @timer:      hrtimer to forward
 451  * @interval:   the interval to forward
 452  *
 453  * Forward the timer expiry so it will expire after the current time
 454  * of the hrtimer clock base. Returns the number of overruns.
 455  *
 456  * Can be safely called from the callback function of @timer. If
 457  * called from other contexts @timer must neither be enqueued nor
 458  * running the callback and the caller needs to take care of
 459  * serialization.
 460  *
 461  * Note: This only updates the timer expiry value and does not requeue
 462  * the timer.
 463  */
 464 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 465                                       ktime_t interval)
 466 {
 467         return hrtimer_forward(timer, timer->base->get_time(), interval);
 468 }
 469
 470 /* Precise sleep: */
 471 extern long hrtimer_nanosleep(struct timespec *rqtp,
 472                               struct timespec __user *rmtp,
 473                               const enum hrtimer_mode mode,
 474                               const clockid_t clockid);
 475 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
 476
 477 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
 478                                  struct task_struct *tsk);
 479
 480 extern int schedule_hrtimeout_range(ktime_t *expires, u64 delta,
 481                                                 const enum hrtimer_mode mode);
 482 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
 483                                           u64 delta,
 484                                           const enum hrtimer_mode mode,
 485                                           int clock);
 486 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
 487
 488 /* Soft interrupt function to run the hrtimer queues: */
 489 extern void hrtimer_run_queues(void);
 490
 491 /* Bootup initialization: */
 492 extern void __init hrtimers_init(void);
 493
 494 /* Show pending timers: */
 495 extern void sysrq_timer_list_show(void);
 496
 497 #endif