include/linux/hrtimer.h

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  hrtimers - High-resolution kernel timers
   4  *
   5  *   Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
   6  *   Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
   7  *
   8  *  data type definitions, declarations, prototypes
   9  *
  10  *  Started by: Thomas Gleixner and Ingo Molnar
  11  */
  12 #ifndef _LINUX_HRTIMER_H
  13 #define _LINUX_HRTIMER_H
  14
  15 #include <linux/hrtimer_defs.h>
  16 #include <linux/hrtimer_types.h>
  17 #include <linux/init.h>
  18 #include <linux/list.h>
  19 #include <linux/percpu-defs.h>
  20 #include <linux/rbtree.h>
  21 #include <linux/timer.h>
  22
  23 /*
  24  * Mode arguments of xxx_hrtimer functions:
  25  *
  26  * HRTIMER_MODE_ABS             - Time value is absolute
  27  * HRTIMER_MODE_REL             - Time value is relative to now
  28  * HRTIMER_MODE_PINNED          - Timer is bound to CPU (is only considered
  29  *                                when starting the timer)
  30  * HRTIMER_MODE_SOFT            - Timer callback function will be executed in
  31  *                                soft irq context
  32  * HRTIMER_MODE_HARD            - Timer callback function will be executed in
  33  *                                hard irq context even on PREEMPT_RT.
  34  */
  35 enum hrtimer_mode {
  36         HRTIMER_MODE_ABS        = 0x00,
  37         HRTIMER_MODE_REL        = 0x01,
  38         HRTIMER_MODE_PINNED     = 0x02,
  39         HRTIMER_MODE_SOFT       = 0x04,
  40         HRTIMER_MODE_HARD       = 0x08,
  41
  42         HRTIMER_MODE_ABS_PINNED = HRTIMER_MODE_ABS | HRTIMER_MODE_PINNED,
  43         HRTIMER_MODE_REL_PINNED = HRTIMER_MODE_REL | HRTIMER_MODE_PINNED,
  44
  45         HRTIMER_MODE_ABS_SOFT   = HRTIMER_MODE_ABS | HRTIMER_MODE_SOFT,
  46         HRTIMER_MODE_REL_SOFT   = HRTIMER_MODE_REL | HRTIMER_MODE_SOFT,
  47
  48         HRTIMER_MODE_ABS_PINNED_SOFT = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_SOFT,
  49         HRTIMER_MODE_REL_PINNED_SOFT = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_SOFT,
  50
  51         HRTIMER_MODE_ABS_HARD   = HRTIMER_MODE_ABS | HRTIMER_MODE_HARD,
  52         HRTIMER_MODE_REL_HARD   = HRTIMER_MODE_REL | HRTIMER_MODE_HARD,
  53
  54         HRTIMER_MODE_ABS_PINNED_HARD = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_HARD,
  55         HRTIMER_MODE_REL_PINNED_HARD = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_HARD,
  56 };
  57
  58 /*
  59  * Values to track state of the timer
  60  *
  61  * Possible states:
  62  *
  63  * 0x00         inactive
  64  * 0x01         enqueued into rbtree
  65  *
  66  * The callback state is not part of the timer->state because clearing it would
  67  * mean touching the timer after the callback, this makes it impossible to free
  68  * the timer from the callback function.
  69  *
  70  * Therefore we track the callback state in:
  71  *
  72  *      timer->base->cpu_base->running == timer
  73  *
  74  * On SMP it is possible to have a "callback function running and enqueued"
  75  * status. It happens for example when a posix timer expired and the callback
  76  * queued a signal. Between dropping the lock which protects the posix timer
  77  * and reacquiring the base lock of the hrtimer, another CPU can deliver the
  78  * signal and rearm the timer.
  79  *
  80  * All state transitions are protected by cpu_base->lock.
  81  */
  82 #define HRTIMER_STATE_INACTIVE  0x00
  83 #define HRTIMER_STATE_ENQUEUED  0x01
  84
  85 /**
  86  * struct hrtimer_sleeper - simple sleeper structure
  87  * @timer:      embedded timer structure
  88  * @task:       task to wake up
  89  *
  90  * task is set to NULL, when the timer expires.
  91  */
  92 struct hrtimer_sleeper {
  93         struct hrtimer timer;
  94         struct task_struct *task;
  95 };
  96
  97 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
  98 {
  99         timer->node.expires = time;
 100         timer->_softexpires = time;
 101 }
 102
 103 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
 104 {
 105         timer->_softexpires = time;
 106         timer->node.expires = ktime_add_safe(time, delta);
 107 }
 108
 109 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, u64 delta)
 110 {
 111         timer->_softexpires = time;
 112         timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
 113 }
 114
 115 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
 116 {
 117         timer->node.expires = tv64;
 118         timer->_softexpires = tv64;
 119 }
 120
 121 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
 122 {
 123         timer->node.expires = ktime_add_safe(timer->node.expires, time);
 124         timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
 125 }
 126
 127 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
 128 {
 129         timer->node.expires = ktime_add_ns(timer->node.expires, ns);
 130         timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
 131 }
 132
 133 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
 134 {
 135         return timer->node.expires;
 136 }
 137
 138 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
 139 {
 140         return timer->_softexpires;
 141 }
 142
 143 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
 144 {
 145         return timer->node.expires;
 146 }
 147 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
 148 {
 149         return timer->_softexpires;
 150 }
 151
 152 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
 153 {
 154         return ktime_to_ns(timer->node.expires);
 155 }
 156
 157 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
 158 {
 159         return ktime_sub(timer->node.expires, timer->base->get_time());
 160 }
 161
 162 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
 163 {
 164         return timer->base->get_time();
 165 }
 166
 167 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
 168 {
 169         return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
 170                 timer->base->cpu_base->hres_active : 0;
 171 }
 172
 173 #ifdef CONFIG_HIGH_RES_TIMERS
 174 struct clock_event_device;
 175
 176 extern void hrtimer_interrupt(struct clock_event_device *dev);
 177
 178 extern unsigned int hrtimer_resolution;
 179
 180 #else
 181
 182 #define hrtimer_resolution      (unsigned int)LOW_RES_NSEC
 183
 184 #endif
 185
 186 static inline ktime_t
 187 __hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now)
 188 {
 189         ktime_t rem = ktime_sub(timer->node.expires, now);
 190
 191         /*
 192          * Adjust relative timers for the extra we added in
 193          * hrtimer_start_range_ns() to prevent short timeouts.
 194          */
 195         if (IS_ENABLED(CONFIG_TIME_LOW_RES) && timer->is_rel)
 196                 rem -= hrtimer_resolution;
 197         return rem;
 198 }
 199
 200 static inline ktime_t
 201 hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
 202 {
 203         return __hrtimer_expires_remaining_adjusted(timer,
 204                                                     timer->base->get_time());
 205 }
 206
 207 #ifdef CONFIG_TIMERFD
 208 extern void timerfd_clock_was_set(void);
 209 extern void timerfd_resume(void);
 210 #else
 211 static inline void timerfd_clock_was_set(void) { }
 212 static inline void timerfd_resume(void) { }
 213 #endif
 214
 215 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
 216
 217 #ifdef CONFIG_PREEMPT_RT
 218 void hrtimer_cancel_wait_running(const struct hrtimer *timer);
 219 #else
 220 static inline void hrtimer_cancel_wait_running(struct hrtimer *timer)
 221 {
 222         cpu_relax();
 223 }
 224 #endif
 225
 226 /* Exported timer functions: */
 227
 228 /* Initialize timers: */
 229 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
 230                          enum hrtimer_mode mode);
 231 extern void hrtimer_setup(struct hrtimer *timer, enum hrtimer_restart (*function)(struct hrtimer *),
 232                           clockid_t clock_id, enum hrtimer_mode mode);
 233 extern void hrtimer_setup_on_stack(struct hrtimer *timer,
 234                                    enum hrtimer_restart (*function)(struct hrtimer *),
 235                                    clockid_t clock_id, enum hrtimer_mode mode);
 236 extern void hrtimer_setup_sleeper_on_stack(struct hrtimer_sleeper *sl, clockid_t clock_id,
 237                                            enum hrtimer_mode mode);
 238
 239 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
 240 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
 241 #else
 242 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
 243 #endif
 244
 245 /* Basic timer operations: */
 246 extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
 247                                    u64 range_ns, const enum hrtimer_mode mode);
 248
 249 /**
 250  * hrtimer_start - (re)start an hrtimer
 251  * @timer:      the timer to be added
 252  * @tim:        expiry time
 253  * @mode:       timer mode: absolute (HRTIMER_MODE_ABS) or
 254  *              relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
 255  *              softirq based mode is considered for debug purpose only!
 256  */
 257 static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
 258                                  const enum hrtimer_mode mode)
 259 {
 260         hrtimer_start_range_ns(timer, tim, 0, mode);
 261 }
 262
 263 extern int hrtimer_cancel(struct hrtimer *timer);
 264 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
 265
 266 static inline void hrtimer_start_expires(struct hrtimer *timer,
 267                                          enum hrtimer_mode mode)
 268 {
 269         u64 delta;
 270         ktime_t soft, hard;
 271         soft = hrtimer_get_softexpires(timer);
 272         hard = hrtimer_get_expires(timer);
 273         delta = ktime_to_ns(ktime_sub(hard, soft));
 274         hrtimer_start_range_ns(timer, soft, delta, mode);
 275 }
 276
 277 void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
 278                                    enum hrtimer_mode mode);
 279
 280 static inline void hrtimer_restart(struct hrtimer *timer)
 281 {
 282         hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
 283 }
 284
 285 /* Query timers: */
 286 extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);
 287
 288 /**
 289  * hrtimer_get_remaining - get remaining time for the timer
 290  * @timer:      the timer to read
 291  */
 292 static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
 293 {
 294         return __hrtimer_get_remaining(timer, false);
 295 }
 296
 297 extern u64 hrtimer_get_next_event(void);
 298 extern u64 hrtimer_next_event_without(const struct hrtimer *exclude);
 299
 300 extern bool hrtimer_active(const struct hrtimer *timer);
 301
 302 /**
 303  * hrtimer_is_queued - check, whether the timer is on one of the queues
 304  * @timer:      Timer to check
 305  *
 306  * Returns: True if the timer is queued, false otherwise
 307  *
 308  * The function can be used lockless, but it gives only a current snapshot.
 309  */
 310 static inline bool hrtimer_is_queued(struct hrtimer *timer)
 311 {
 312         /* The READ_ONCE pairs with the update functions of timer->state */
 313         return !!(READ_ONCE(timer->state) & HRTIMER_STATE_ENQUEUED);
 314 }
 315
 316 /*
 317  * Helper function to check, whether the timer is running the callback
 318  * function
 319  */
 320 static inline int hrtimer_callback_running(struct hrtimer *timer)
 321 {
 322         return timer->base->running == timer;
 323 }
 324
 325 /**
 326  * hrtimer_update_function - Update the timer's callback function
 327  * @timer:      Timer to update
 328  * @function:   New callback function
 329  *
 330  * Only safe to call if the timer is not enqueued. Can be called in the callback function if the
 331  * timer is not enqueued at the same time (see the comments above HRTIMER_STATE_ENQUEUED).
 332  */
 333 static inline void hrtimer_update_function(struct hrtimer *timer,
 334                                            enum hrtimer_restart (*function)(struct hrtimer *))
 335 {
 336         guard(raw_spinlock_irqsave)(&timer->base->cpu_base->lock);
 337
 338         if (WARN_ON_ONCE(hrtimer_is_queued(timer)))
 339                 return;
 340
 341         if (WARN_ON_ONCE(!function))
 342                 return;
 343
 344         timer->function = function;
 345 }
 346
 347 /* Forward a hrtimer so it expires after now: */
 348 extern u64
 349 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
 350
 351 /**
 352  * hrtimer_forward_now() - forward the timer expiry so it expires after now
 353  * @timer:      hrtimer to forward
 354  * @interval:   the interval to forward
 355  *
 356  * It is a variant of hrtimer_forward(). The timer will expire after the current
 357  * time of the hrtimer clock base. See hrtimer_forward() for details.
 358  */
 359 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
 360                                       ktime_t interval)
 361 {
 362         return hrtimer_forward(timer, timer->base->get_time(), interval);
 363 }
 364
 365 /* Precise sleep: */
 366
 367 extern int nanosleep_copyout(struct restart_block *, struct timespec64 *);
 368 extern long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
 369                               const clockid_t clockid);
 370
 371 extern int schedule_hrtimeout_range(ktime_t *expires, u64 delta,
 372                                     const enum hrtimer_mode mode);
 373 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
 374                                           u64 delta,
 375                                           const enum hrtimer_mode mode,
 376                                           clockid_t clock_id);
 377 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
 378
 379 /* Soft interrupt function to run the hrtimer queues: */
 380 extern void hrtimer_run_queues(void);
 381
 382 /* Bootup initialization: */
 383 extern void __init hrtimers_init(void);
 384
 385 /* Show pending timers: */
 386 extern void sysrq_timer_list_show(void);
 387
 388 int hrtimers_prepare_cpu(unsigned int cpu);
 389 #ifdef CONFIG_HOTPLUG_CPU
 390 int hrtimers_cpu_dying(unsigned int cpu);
 391 #else
 392 #define hrtimers_cpu_dying      NULL
 393 #endif
 394
 395 #endif