2 * include/linux/hrtimer.h
4 * hrtimers - High-resolution kernel timers
6 * Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
7 * Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
9 * data type definitions, declarations, prototypes
11 * Started by: Thomas Gleixner and Ingo Molnar
13 * For licencing details see kernel-base/COPYING
15 #ifndef _LINUX_HRTIMER_H
16 #define _LINUX_HRTIMER_H
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>
27 struct hrtimer_clock_base;
28 struct hrtimer_cpu_base;
31 * Mode arguments of xxx_hrtimer functions:
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,
42 * Return values for the callback function
44 enum hrtimer_restart {
45 HRTIMER_NORESTART, /* Timer is not restarted */
46 HRTIMER_RESTART, /* Timer must be restarted */
50 * Values to track state of the timer
55 * 0x01 enqueued into rbtree
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.
61 * Therefore we track the callback state in:
63 * timer->base->cpu_base->running == timer
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.
71 * All state transitions are protected by cpu_base->lock.
73 #define HRTIMER_STATE_INACTIVE 0x00
74 #define HRTIMER_STATE_ENQUEUED 0x01
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
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 * @cb_entry: list entry to defer timers from hardirq context
91 * @irqsafe: timer can run in hardirq context
92 * @praecox: timer expiry time if expired at the time of programming
93 * @is_rel: Set if the timer was armed relative
94 * @start_pid: timer statistics field to store the pid of the task which
96 * @start_site: timer statistics field to store the site where the timer
98 * @start_comm: timer statistics field to store the name of the process which
101 * The hrtimer structure must be initialized by hrtimer_init()
104 struct timerqueue_node node;
105 ktime_t _softexpires;
106 enum hrtimer_restart (*function)(struct hrtimer *);
107 struct hrtimer_clock_base *base;
109 struct list_head cb_entry;
111 #ifdef CONFIG_MISSED_TIMER_OFFSETS_HIST
115 #ifdef CONFIG_TIMER_STATS
123 * struct hrtimer_sleeper - simple sleeper structure
124 * @timer: embedded timer structure
125 * @task: task to wake up
127 * task is set to NULL, when the timer expires.
129 struct hrtimer_sleeper {
130 struct hrtimer timer;
131 struct task_struct *task;
134 # define HRTIMER_CLOCK_BASE_ALIGN 64
137 * struct hrtimer_clock_base - the timer base for a specific clock
138 * @cpu_base: per cpu clock base
139 * @index: clock type index for per_cpu support when moving a
140 * timer to a base on another cpu.
141 * @clockid: clock id for per_cpu support
142 * @active: red black tree root node for the active timers
143 * @expired: list head for deferred timers.
144 * @get_time: function to retrieve the current time of the clock
145 * @offset: offset of this clock to the monotonic base
147 struct hrtimer_clock_base {
148 struct hrtimer_cpu_base *cpu_base;
151 struct timerqueue_head active;
152 struct list_head expired;
153 ktime_t (*get_time)(void);
155 } __attribute__((__aligned__(HRTIMER_CLOCK_BASE_ALIGN)));
157 enum hrtimer_base_type {
158 HRTIMER_BASE_MONOTONIC,
159 HRTIMER_BASE_REALTIME,
160 HRTIMER_BASE_BOOTTIME,
162 HRTIMER_MAX_CLOCK_BASES,
166 * struct hrtimer_cpu_base - the per cpu clock bases
167 * @lock: lock protecting the base and associated clock bases
169 * @seq: seqcount around __run_hrtimer
170 * @running: pointer to the currently running hrtimer
172 * @active_bases: Bitfield to mark bases with active timers
173 * @clock_was_set_seq: Sequence counter of clock was set events
174 * @migration_enabled: The migration of hrtimers to other cpus is enabled
175 * @nohz_active: The nohz functionality is enabled
176 * @expires_next: absolute time of the next event which was scheduled
177 * via clock_set_next_event()
178 * @next_timer: Pointer to the first expiring timer
179 * @in_hrtirq: hrtimer_interrupt() is currently executing
180 * @hres_active: State of high resolution mode
181 * @hang_detected: The last hrtimer interrupt detected a hang
182 * @nr_events: Total number of hrtimer interrupt events
183 * @nr_retries: Total number of hrtimer interrupt retries
184 * @nr_hangs: Total number of hrtimer interrupt hangs
185 * @max_hang_time: Maximum time spent in hrtimer_interrupt
186 * @clock_base: array of clock bases for this cpu
188 * Note: next_timer is just an optimization for __remove_hrtimer().
189 * Do not dereference the pointer because it is not reliable on
190 * cross cpu removals.
192 struct hrtimer_cpu_base {
195 struct hrtimer *running;
196 struct hrtimer *running_soft;
198 unsigned int active_bases;
199 unsigned int clock_was_set_seq;
200 bool migration_enabled;
202 #ifdef CONFIG_HIGH_RES_TIMERS
203 unsigned int in_hrtirq : 1,
206 ktime_t expires_next;
207 struct hrtimer *next_timer;
208 unsigned int nr_events;
209 unsigned int nr_retries;
210 unsigned int nr_hangs;
211 unsigned int max_hang_time;
213 #ifdef CONFIG_PREEMPT_RT_BASE
214 wait_queue_head_t wait;
216 struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
217 } ____cacheline_aligned;
219 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
221 BUILD_BUG_ON(sizeof(struct hrtimer_clock_base) > HRTIMER_CLOCK_BASE_ALIGN);
223 timer->node.expires = time;
224 timer->_softexpires = time;
227 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
229 timer->_softexpires = time;
230 timer->node.expires = ktime_add_safe(time, delta);
233 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
235 timer->_softexpires = time;
236 timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
239 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
241 timer->node.expires.tv64 = tv64;
242 timer->_softexpires.tv64 = tv64;
245 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
247 timer->node.expires = ktime_add_safe(timer->node.expires, time);
248 timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
251 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
253 timer->node.expires = ktime_add_ns(timer->node.expires, ns);
254 timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
257 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
259 return timer->node.expires;
262 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
264 return timer->_softexpires;
267 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
269 return timer->node.expires.tv64;
271 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
273 return timer->_softexpires.tv64;
276 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
278 return ktime_to_ns(timer->node.expires);
281 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
283 return ktime_sub(timer->node.expires, timer->base->get_time());
286 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
288 return timer->base->get_time();
291 #ifdef CONFIG_HIGH_RES_TIMERS
292 struct clock_event_device;
294 extern void hrtimer_interrupt(struct clock_event_device *dev);
296 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
298 return timer->base->cpu_base->hres_active;
301 extern void hrtimer_peek_ahead_timers(void);
304 * The resolution of the clocks. The resolution value is returned in
305 * the clock_getres() system call to give application programmers an
306 * idea of the (in)accuracy of timers. Timer values are rounded up to
307 * this resolution values.
309 # define HIGH_RES_NSEC 1
310 # define KTIME_HIGH_RES (ktime_t) { .tv64 = HIGH_RES_NSEC }
311 # define MONOTONIC_RES_NSEC HIGH_RES_NSEC
312 # define KTIME_MONOTONIC_RES KTIME_HIGH_RES
314 extern void clock_was_set_delayed(void);
316 extern unsigned int hrtimer_resolution;
320 # define MONOTONIC_RES_NSEC LOW_RES_NSEC
321 # define KTIME_MONOTONIC_RES KTIME_LOW_RES
323 #define hrtimer_resolution (unsigned int)LOW_RES_NSEC
325 static inline void hrtimer_peek_ahead_timers(void) { }
327 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
332 static inline void clock_was_set_delayed(void) { }
336 static inline ktime_t
337 __hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now)
339 ktime_t rem = ktime_sub(timer->node.expires, now);
342 * Adjust relative timers for the extra we added in
343 * hrtimer_start_range_ns() to prevent short timeouts.
345 if (IS_ENABLED(CONFIG_TIME_LOW_RES) && timer->is_rel)
346 rem.tv64 -= hrtimer_resolution;
350 static inline ktime_t
351 hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
353 return __hrtimer_expires_remaining_adjusted(timer,
354 timer->base->get_time());
357 extern void clock_was_set(void);
358 #ifdef CONFIG_TIMERFD
359 extern void timerfd_clock_was_set(void);
361 static inline void timerfd_clock_was_set(void) { }
363 extern void hrtimers_resume(void);
365 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
368 /* Exported timer functions: */
370 /* Initialize timers: */
371 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
372 enum hrtimer_mode mode);
374 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
375 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
376 enum hrtimer_mode mode);
378 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
380 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
381 clockid_t which_clock,
382 enum hrtimer_mode mode)
384 hrtimer_init(timer, which_clock, mode);
386 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
389 /* Basic timer operations: */
390 extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
391 unsigned long range_ns, const enum hrtimer_mode mode);
394 * hrtimer_start - (re)start an hrtimer on the current CPU
395 * @timer: the timer to be added
397 * @mode: expiry mode: absolute (HRTIMER_MODE_ABS) or
398 * relative (HRTIMER_MODE_REL)
400 static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
401 const enum hrtimer_mode mode)
403 hrtimer_start_range_ns(timer, tim, 0, mode);
406 extern int hrtimer_cancel(struct hrtimer *timer);
407 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
409 static inline void hrtimer_start_expires(struct hrtimer *timer,
410 enum hrtimer_mode mode)
414 soft = hrtimer_get_softexpires(timer);
415 hard = hrtimer_get_expires(timer);
416 delta = ktime_to_ns(ktime_sub(hard, soft));
417 hrtimer_start_range_ns(timer, soft, delta, mode);
420 static inline void hrtimer_restart(struct hrtimer *timer)
422 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
425 /* Softirq preemption could deadlock timer removal */
426 #ifdef CONFIG_PREEMPT_RT_BASE
427 extern void hrtimer_wait_for_timer(const struct hrtimer *timer);
429 # define hrtimer_wait_for_timer(timer) do { cpu_relax(); } while (0)
433 extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);
435 static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
437 return __hrtimer_get_remaining(timer, false);
440 extern u64 hrtimer_get_next_event(void);
442 extern bool hrtimer_active(const struct hrtimer *timer);
445 * Helper function to check, whether the timer is on one of the queues
447 static inline int hrtimer_is_queued(struct hrtimer *timer)
449 return timer->state & HRTIMER_STATE_ENQUEUED;
453 * Helper function to check, whether the timer is running the callback
456 static inline int hrtimer_callback_running(const struct hrtimer *timer)
458 return timer->base->cpu_base->running == timer;
461 /* Forward a hrtimer so it expires after now: */
463 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
466 * hrtimer_forward_now - forward the timer expiry so it expires after now
467 * @timer: hrtimer to forward
468 * @interval: the interval to forward
470 * Forward the timer expiry so it will expire after the current time
471 * of the hrtimer clock base. Returns the number of overruns.
473 * Can be safely called from the callback function of @timer. If
474 * called from other contexts @timer must neither be enqueued nor
475 * running the callback and the caller needs to take care of
478 * Note: This only updates the timer expiry value and does not requeue
481 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
484 return hrtimer_forward(timer, timer->base->get_time(), interval);
488 extern long hrtimer_nanosleep(struct timespec *rqtp,
489 struct timespec __user *rmtp,
490 const enum hrtimer_mode mode,
491 const clockid_t clockid);
492 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
494 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
495 struct task_struct *tsk);
497 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
498 const enum hrtimer_mode mode);
499 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
500 unsigned long delta, const enum hrtimer_mode mode, int clock);
501 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
503 /* Soft interrupt function to run the hrtimer queues: */
504 extern void hrtimer_run_queues(void);
506 /* Bootup initialization: */
507 extern void __init hrtimers_init(void);
509 /* Show pending timers: */
510 extern void sysrq_timer_list_show(void);