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
56 * 0x02 callback function running
57 * 0x04 timer is migrated to another cpu
60 * 0x03 callback function running and enqueued
61 * (was requeued on another CPU)
62 * 0x05 timer was migrated on CPU hotunplug
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.
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.
78 * All state transitions are protected by cpu_base->lock.
80 #define HRTIMER_STATE_INACTIVE 0x00
81 #define HRTIMER_STATE_ENQUEUED 0x01
82 #define HRTIMER_STATE_CALLBACK 0x02
83 #define HRTIMER_STATE_MIGRATE 0x04
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
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
101 * @start_site: timer statistics field to store the site where the timer
103 * @start_comm: timer statistics field to store the name of the process which
106 * The hrtimer structure must be initialized by hrtimer_init()
109 struct timerqueue_node node;
110 ktime_t _softexpires;
111 enum hrtimer_restart (*function)(struct hrtimer *);
112 struct hrtimer_clock_base *base;
114 #ifdef CONFIG_TIMER_STATS
122 * struct hrtimer_sleeper - simple sleeper structure
123 * @timer: embedded timer structure
124 * @task: task to wake up
126 * task is set to NULL, when the timer expires.
128 struct hrtimer_sleeper {
129 struct hrtimer timer;
130 struct task_struct *task;
134 # define HRTIMER_CLOCK_BASE_ALIGN 64
136 # define HRTIMER_CLOCK_BASE_ALIGN 32
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
149 struct hrtimer_clock_base {
150 struct hrtimer_cpu_base *cpu_base;
153 struct timerqueue_head active;
154 ktime_t (*get_time)(void);
156 } __attribute__((__aligned__(HRTIMER_CLOCK_BASE_ALIGN)));
158 enum hrtimer_base_type {
159 HRTIMER_BASE_MONOTONIC,
160 HRTIMER_BASE_REALTIME,
161 HRTIMER_BASE_BOOTTIME,
163 HRTIMER_MAX_CLOCK_BASES,
167 * struct hrtimer_cpu_base - the per cpu clock bases
168 * @lock: lock protecting the base and associated clock bases
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
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.
189 struct hrtimer_cpu_base {
192 unsigned int active_bases;
193 unsigned int clock_was_set_seq;
194 #ifdef CONFIG_HIGH_RES_TIMERS
195 unsigned int in_hrtirq : 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;
205 struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
206 } ____cacheline_aligned;
208 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
210 BUILD_BUG_ON(sizeof(struct hrtimer_clock_base) > HRTIMER_CLOCK_BASE_ALIGN);
212 timer->node.expires = time;
213 timer->_softexpires = time;
216 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
218 timer->_softexpires = time;
219 timer->node.expires = ktime_add_safe(time, delta);
222 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
224 timer->_softexpires = time;
225 timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
228 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
230 timer->node.expires.tv64 = tv64;
231 timer->_softexpires.tv64 = tv64;
234 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
236 timer->node.expires = ktime_add_safe(timer->node.expires, time);
237 timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
240 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
242 timer->node.expires = ktime_add_ns(timer->node.expires, ns);
243 timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
246 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
248 return timer->node.expires;
251 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
253 return timer->_softexpires;
256 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
258 return timer->node.expires.tv64;
260 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
262 return timer->_softexpires.tv64;
265 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
267 return ktime_to_ns(timer->node.expires);
270 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
272 return ktime_sub(timer->node.expires, timer->base->get_time());
275 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
277 return timer->base->get_time();
280 #ifdef CONFIG_HIGH_RES_TIMERS
281 struct clock_event_device;
283 extern void hrtimer_interrupt(struct clock_event_device *dev);
285 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
287 return timer->base->cpu_base->hres_active;
290 extern void hrtimer_peek_ahead_timers(void);
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.
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
303 extern void clock_was_set_delayed(void);
305 extern unsigned int hrtimer_resolution;
309 # define MONOTONIC_RES_NSEC LOW_RES_NSEC
310 # define KTIME_MONOTONIC_RES KTIME_LOW_RES
312 #define hrtimer_resolution LOW_RES_NSEC
314 static inline void hrtimer_peek_ahead_timers(void) { }
316 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
321 static inline void clock_was_set_delayed(void) { }
325 extern void clock_was_set(void);
326 #ifdef CONFIG_TIMERFD
327 extern void timerfd_clock_was_set(void);
329 static inline void timerfd_clock_was_set(void) { }
331 extern void hrtimers_resume(void);
333 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
336 /* Exported timer functions: */
338 /* Initialize timers: */
339 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
340 enum hrtimer_mode mode);
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);
346 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
348 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
349 clockid_t which_clock,
350 enum hrtimer_mode mode)
352 hrtimer_init(timer, which_clock, mode);
354 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
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);
363 __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
364 unsigned long delta_ns,
365 const enum hrtimer_mode mode, int wakeup);
367 extern int hrtimer_cancel(struct hrtimer *timer);
368 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
370 static inline int hrtimer_start_expires(struct hrtimer *timer,
371 enum hrtimer_mode mode)
375 soft = hrtimer_get_softexpires(timer);
376 hard = hrtimer_get_expires(timer);
377 delta = ktime_to_ns(ktime_sub(hard, soft));
378 return hrtimer_start_range_ns(timer, soft, delta, mode);
381 static inline int hrtimer_restart(struct hrtimer *timer)
383 return hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
387 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
389 extern ktime_t hrtimer_get_next_event(void);
392 * A timer is active, when it is enqueued into the rbtree or the
393 * callback function is running or it's in the state of being migrated
396 static inline int hrtimer_active(const struct hrtimer *timer)
398 return timer->state != HRTIMER_STATE_INACTIVE;
402 * Helper function to check, whether the timer is on one of the queues
404 static inline int hrtimer_is_queued(struct hrtimer *timer)
406 return timer->state & HRTIMER_STATE_ENQUEUED;
410 * Helper function to check, whether the timer is running the callback
413 static inline int hrtimer_callback_running(struct hrtimer *timer)
415 return timer->state & HRTIMER_STATE_CALLBACK;
418 /* Forward a hrtimer so it expires after now: */
420 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
423 * hrtimer_forward_now - forward the timer expiry so it expires after now
424 * @timer: hrtimer to forward
425 * @interval: the interval to forward
427 * Forward the timer expiry so it will expire after the current time
428 * of the hrtimer clock base. Returns the number of overruns.
430 * Can be safely called from the callback function of @timer. If
431 * called from other contexts @timer must neither be enqueued nor
432 * running the callback and the caller needs to take care of
435 * Note: This only updates the timer expiry value and does not requeue
438 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
441 return hrtimer_forward(timer, timer->base->get_time(), interval);
445 extern long hrtimer_nanosleep(struct timespec *rqtp,
446 struct timespec __user *rmtp,
447 const enum hrtimer_mode mode,
448 const clockid_t clockid);
449 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
451 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
452 struct task_struct *tsk);
454 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
455 const enum hrtimer_mode mode);
456 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
457 unsigned long delta, const enum hrtimer_mode mode, int clock);
458 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
460 /* Soft interrupt function to run the hrtimer queues: */
461 extern void hrtimer_run_queues(void);
463 /* Bootup initialization: */
464 extern void __init hrtimers_init(void);
466 /* Show pending timers: */
467 extern void sysrq_timer_list_show(void);