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 * @start_pid: timer statistics field to store the pid of the task which
92 * @start_site: timer statistics field to store the site where the timer
94 * @start_comm: timer statistics field to store the name of the process which
97 * The hrtimer structure must be initialized by hrtimer_init()
100 struct timerqueue_node node;
101 ktime_t _softexpires;
102 enum hrtimer_restart (*function)(struct hrtimer *);
103 struct hrtimer_clock_base *base;
105 #ifdef CONFIG_TIMER_STATS
113 * struct hrtimer_sleeper - simple sleeper structure
114 * @timer: embedded timer structure
115 * @task: task to wake up
117 * task is set to NULL, when the timer expires.
119 struct hrtimer_sleeper {
120 struct hrtimer timer;
121 struct task_struct *task;
125 # define HRTIMER_CLOCK_BASE_ALIGN 64
127 # define HRTIMER_CLOCK_BASE_ALIGN 32
131 * struct hrtimer_clock_base - the timer base for a specific clock
132 * @cpu_base: per cpu clock base
133 * @index: clock type index for per_cpu support when moving a
134 * timer to a base on another cpu.
135 * @clockid: clock id for per_cpu support
136 * @active: red black tree root node for the active timers
137 * @get_time: function to retrieve the current time of the clock
138 * @offset: offset of this clock to the monotonic base
140 struct hrtimer_clock_base {
141 struct hrtimer_cpu_base *cpu_base;
144 struct timerqueue_head active;
145 ktime_t (*get_time)(void);
147 } __attribute__((__aligned__(HRTIMER_CLOCK_BASE_ALIGN)));
149 enum hrtimer_base_type {
150 HRTIMER_BASE_MONOTONIC,
151 HRTIMER_BASE_REALTIME,
152 HRTIMER_BASE_BOOTTIME,
154 HRTIMER_MAX_CLOCK_BASES,
158 * struct hrtimer_cpu_base - the per cpu clock bases
159 * @lock: lock protecting the base and associated clock bases
161 * @seq: seqcount around __run_hrtimer
162 * @running: pointer to the currently running hrtimer
164 * @active_bases: Bitfield to mark bases with active timers
165 * @clock_was_set_seq: Sequence counter of clock was set events
166 * @expires_next: absolute time of the next event which was scheduled
167 * via clock_set_next_event()
168 * @next_timer: Pointer to the first expiring timer
169 * @in_hrtirq: hrtimer_interrupt() is currently executing
170 * @hres_active: State of high resolution mode
171 * @hang_detected: The last hrtimer interrupt detected a hang
172 * @nr_events: Total number of hrtimer interrupt events
173 * @nr_retries: Total number of hrtimer interrupt retries
174 * @nr_hangs: Total number of hrtimer interrupt hangs
175 * @max_hang_time: Maximum time spent in hrtimer_interrupt
176 * @clock_base: array of clock bases for this cpu
178 * Note: next_timer is just an optimization for __remove_hrtimer().
179 * Do not dereference the pointer because it is not reliable on
180 * cross cpu removals.
182 struct hrtimer_cpu_base {
185 struct hrtimer *running;
187 unsigned int active_bases;
188 unsigned int clock_was_set_seq;
189 #ifdef CONFIG_HIGH_RES_TIMERS
190 unsigned int in_hrtirq : 1,
193 ktime_t expires_next;
194 struct hrtimer *next_timer;
195 unsigned int nr_events;
196 unsigned int nr_retries;
197 unsigned int nr_hangs;
198 unsigned int max_hang_time;
200 struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
201 } ____cacheline_aligned;
203 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
205 BUILD_BUG_ON(sizeof(struct hrtimer_clock_base) > HRTIMER_CLOCK_BASE_ALIGN);
207 timer->node.expires = time;
208 timer->_softexpires = time;
211 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
213 timer->_softexpires = time;
214 timer->node.expires = ktime_add_safe(time, delta);
217 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
219 timer->_softexpires = time;
220 timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
223 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
225 timer->node.expires.tv64 = tv64;
226 timer->_softexpires.tv64 = tv64;
229 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
231 timer->node.expires = ktime_add_safe(timer->node.expires, time);
232 timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
235 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
237 timer->node.expires = ktime_add_ns(timer->node.expires, ns);
238 timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
241 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
243 return timer->node.expires;
246 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
248 return timer->_softexpires;
251 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
253 return timer->node.expires.tv64;
255 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
257 return timer->_softexpires.tv64;
260 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
262 return ktime_to_ns(timer->node.expires);
265 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
267 return ktime_sub(timer->node.expires, timer->base->get_time());
270 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
272 return timer->base->get_time();
275 #ifdef CONFIG_HIGH_RES_TIMERS
276 struct clock_event_device;
278 extern void hrtimer_interrupt(struct clock_event_device *dev);
280 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
282 return timer->base->cpu_base->hres_active;
285 extern void hrtimer_peek_ahead_timers(void);
288 * The resolution of the clocks. The resolution value is returned in
289 * the clock_getres() system call to give application programmers an
290 * idea of the (in)accuracy of timers. Timer values are rounded up to
291 * this resolution values.
293 # define HIGH_RES_NSEC 1
294 # define KTIME_HIGH_RES (ktime_t) { .tv64 = HIGH_RES_NSEC }
295 # define MONOTONIC_RES_NSEC HIGH_RES_NSEC
296 # define KTIME_MONOTONIC_RES KTIME_HIGH_RES
298 extern void clock_was_set_delayed(void);
300 extern unsigned int hrtimer_resolution;
304 # define MONOTONIC_RES_NSEC LOW_RES_NSEC
305 # define KTIME_MONOTONIC_RES KTIME_LOW_RES
307 #define hrtimer_resolution (unsigned int)LOW_RES_NSEC
309 static inline void hrtimer_peek_ahead_timers(void) { }
311 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
316 static inline void clock_was_set_delayed(void) { }
320 extern void clock_was_set(void);
321 #ifdef CONFIG_TIMERFD
322 extern void timerfd_clock_was_set(void);
324 static inline void timerfd_clock_was_set(void) { }
326 extern void hrtimers_resume(void);
328 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
331 /* Exported timer functions: */
333 /* Initialize timers: */
334 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
335 enum hrtimer_mode mode);
337 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
338 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
339 enum hrtimer_mode mode);
341 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
343 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
344 clockid_t which_clock,
345 enum hrtimer_mode mode)
347 hrtimer_init(timer, which_clock, mode);
349 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
352 /* Basic timer operations: */
353 extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
354 unsigned long range_ns, const enum hrtimer_mode mode);
357 * hrtimer_start - (re)start an hrtimer on the current CPU
358 * @timer: the timer to be added
360 * @mode: expiry mode: absolute (HRTIMER_MODE_ABS) or
361 * relative (HRTIMER_MODE_REL)
363 static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
364 const enum hrtimer_mode mode)
366 hrtimer_start_range_ns(timer, tim, 0, mode);
369 extern int hrtimer_cancel(struct hrtimer *timer);
370 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
372 static inline void hrtimer_start_expires(struct hrtimer *timer,
373 enum hrtimer_mode mode)
377 soft = hrtimer_get_softexpires(timer);
378 hard = hrtimer_get_expires(timer);
379 delta = ktime_to_ns(ktime_sub(hard, soft));
380 hrtimer_start_range_ns(timer, soft, delta, mode);
383 static inline void hrtimer_restart(struct hrtimer *timer)
385 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
389 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
391 extern u64 hrtimer_get_next_event(void);
393 extern bool hrtimer_active(const struct hrtimer *timer);
396 * Helper function to check, whether the timer is on one of the queues
398 static inline int hrtimer_is_queued(struct hrtimer *timer)
400 return timer->state & HRTIMER_STATE_ENQUEUED;
404 * Helper function to check, whether the timer is running the callback
407 static inline int hrtimer_callback_running(struct hrtimer *timer)
409 return timer->base->cpu_base->running == timer;
412 /* Forward a hrtimer so it expires after now: */
414 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
417 * hrtimer_forward_now - forward the timer expiry so it expires after now
418 * @timer: hrtimer to forward
419 * @interval: the interval to forward
421 * Forward the timer expiry so it will expire after the current time
422 * of the hrtimer clock base. Returns the number of overruns.
424 * Can be safely called from the callback function of @timer. If
425 * called from other contexts @timer must neither be enqueued nor
426 * running the callback and the caller needs to take care of
429 * Note: This only updates the timer expiry value and does not requeue
432 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
435 return hrtimer_forward(timer, timer->base->get_time(), interval);
439 extern long hrtimer_nanosleep(struct timespec *rqtp,
440 struct timespec __user *rmtp,
441 const enum hrtimer_mode mode,
442 const clockid_t clockid);
443 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
445 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
446 struct task_struct *tsk);
448 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
449 const enum hrtimer_mode mode);
450 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
451 unsigned long delta, const enum hrtimer_mode mode, int clock);
452 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
454 /* Soft interrupt function to run the hrtimer queues: */
455 extern void hrtimer_run_queues(void);
457 /* Bootup initialization: */
458 extern void __init hrtimers_init(void);
460 /* Show pending timers: */
461 extern void sysrq_timer_list_show(void);