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/rbtree.h>
17#include <linux/init.h>
18#include <linux/list.h>
19#include <linux/percpu.h>
20#include <linux/seqlock.h>
21#include <linux/timer.h>
22#include <linux/timerqueue.h>
23
24struct hrtimer_clock_base;
25struct hrtimer_cpu_base;
26
27/*
28 * Mode arguments of xxx_hrtimer functions:
29 *
30 * HRTIMER_MODE_ABS - Time value is absolute
31 * HRTIMER_MODE_REL - Time value is relative to now
32 * HRTIMER_MODE_PINNED - Timer is bound to CPU (is only considered
33 * when starting the timer)
34 * HRTIMER_MODE_SOFT - Timer callback function will be executed in
35 * soft irq context
36 * HRTIMER_MODE_HARD - Timer callback function will be executed in
37 * hard irq context even on PREEMPT_RT.
38 */
39enum hrtimer_mode {
40 HRTIMER_MODE_ABS = 0x00,
41 HRTIMER_MODE_REL = 0x01,
42 HRTIMER_MODE_PINNED = 0x02,
43 HRTIMER_MODE_SOFT = 0x04,
44 HRTIMER_MODE_HARD = 0x08,
45
46 HRTIMER_MODE_ABS_PINNED = HRTIMER_MODE_ABS | HRTIMER_MODE_PINNED,
47 HRTIMER_MODE_REL_PINNED = HRTIMER_MODE_REL | HRTIMER_MODE_PINNED,
48
49 HRTIMER_MODE_ABS_SOFT = HRTIMER_MODE_ABS | HRTIMER_MODE_SOFT,
50 HRTIMER_MODE_REL_SOFT = HRTIMER_MODE_REL | HRTIMER_MODE_SOFT,
51
52 HRTIMER_MODE_ABS_PINNED_SOFT = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_SOFT,
53 HRTIMER_MODE_REL_PINNED_SOFT = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_SOFT,
54
55 HRTIMER_MODE_ABS_HARD = HRTIMER_MODE_ABS | HRTIMER_MODE_HARD,
56 HRTIMER_MODE_REL_HARD = HRTIMER_MODE_REL | HRTIMER_MODE_HARD,
57
58 HRTIMER_MODE_ABS_PINNED_HARD = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_HARD,
59 HRTIMER_MODE_REL_PINNED_HARD = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_HARD,
60};
61
62/*
63 * Return values for the callback function
64 */
65enum hrtimer_restart {
66 HRTIMER_NORESTART, /* Timer is not restarted */
67 HRTIMER_RESTART, /* Timer must be restarted */
68};
69
70/*
71 * Values to track state of the timer
72 *
73 * Possible states:
74 *
75 * 0x00 inactive
76 * 0x01 enqueued into rbtree
77 *
78 * The callback state is not part of the timer->state because clearing it would
79 * mean touching the timer after the callback, this makes it impossible to free
80 * the timer from the callback function.
81 *
82 * Therefore we track the callback state in:
83 *
84 * timer->base->cpu_base->running == timer
85 *
86 * On SMP it is possible to have a "callback function running and enqueued"
87 * status. It happens for example when a posix timer expired and the callback
88 * queued a signal. Between dropping the lock which protects the posix timer
89 * and reacquiring the base lock of the hrtimer, another CPU can deliver the
90 * signal and rearm the timer.
91 *
92 * All state transitions are protected by cpu_base->lock.
93 */
94#define HRTIMER_STATE_INACTIVE 0x00
95#define HRTIMER_STATE_ENQUEUED 0x01
96
97/**
98 * struct hrtimer - the basic hrtimer structure
99 * @node: timerqueue node, which also manages node.expires,
100 * the absolute expiry time in the hrtimers internal
101 * representation. The time is related to the clock on
102 * which the timer is based. Is setup by adding
103 * slack to the _softexpires value. For non range timers
104 * identical to _softexpires.
105 * @_softexpires: the absolute earliest expiry time of the hrtimer.
106 * The time which was given as expiry time when the timer
107 * was armed.
108 * @function: timer expiry callback function
109 * @base: pointer to the timer base (per cpu and per clock)
110 * @state: state information (See bit values above)
111 * @is_rel: Set if the timer was armed relative
112 * @is_soft: Set if hrtimer will be expired in soft interrupt context.
113 * @is_hard: Set if hrtimer will be expired in hard interrupt context
114 * even on RT.
115 *
116 * The hrtimer structure must be initialized by hrtimer_init()
117 */
118struct hrtimer {
119 struct timerqueue_node node;
120 ktime_t _softexpires;
121 enum hrtimer_restart (*function)(struct hrtimer *);
122 struct hrtimer_clock_base *base;
123 u8 state;
124 u8 is_rel;
125 u8 is_soft;
126 u8 is_hard;
127};
128
129/**
130 * struct hrtimer_sleeper - simple sleeper structure
131 * @timer: embedded timer structure
132 * @task: task to wake up
133 *
134 * task is set to NULL, when the timer expires.
135 */
136struct hrtimer_sleeper {
137 struct hrtimer timer;
138 struct task_struct *task;
139};
140
141#ifdef CONFIG_64BIT
142# define __hrtimer_clock_base_align ____cacheline_aligned
143#else
144# define __hrtimer_clock_base_align
145#endif
146
147/**
148 * struct hrtimer_clock_base - the timer base for a specific clock
149 * @cpu_base: per cpu clock base
150 * @index: clock type index for per_cpu support when moving a
151 * timer to a base on another cpu.
152 * @clockid: clock id for per_cpu support
153 * @seq: seqcount around __run_hrtimer
154 * @running: pointer to the currently running hrtimer
155 * @active: red black tree root node for the active timers
156 * @get_time: function to retrieve the current time of the clock
157 * @offset: offset of this clock to the monotonic base
158 */
159struct hrtimer_clock_base {
160 struct hrtimer_cpu_base *cpu_base;
161 unsigned int index;
162 clockid_t clockid;
163 seqcount_raw_spinlock_t seq;
164 struct hrtimer *running;
165 struct timerqueue_head active;
166 ktime_t (*get_time)(void);
167 ktime_t offset;
168} __hrtimer_clock_base_align;
169
170enum hrtimer_base_type {
171 HRTIMER_BASE_MONOTONIC,
172 HRTIMER_BASE_REALTIME,
173 HRTIMER_BASE_BOOTTIME,
174 HRTIMER_BASE_TAI,
175 HRTIMER_BASE_MONOTONIC_SOFT,
176 HRTIMER_BASE_REALTIME_SOFT,
177 HRTIMER_BASE_BOOTTIME_SOFT,
178 HRTIMER_BASE_TAI_SOFT,
179 HRTIMER_MAX_CLOCK_BASES,
180};
181
182/**
183 * struct hrtimer_cpu_base - the per cpu clock bases
184 * @lock: lock protecting the base and associated clock bases
185 * and timers
186 * @cpu: cpu number
187 * @active_bases: Bitfield to mark bases with active timers
188 * @clock_was_set_seq: Sequence counter of clock was set events
189 * @hres_active: State of high resolution mode
190 * @in_hrtirq: hrtimer_interrupt() is currently executing
191 * @hang_detected: The last hrtimer interrupt detected a hang
192 * @softirq_activated: displays, if the softirq is raised - update of softirq
193 * related settings is not required then.
194 * @nr_events: Total number of hrtimer interrupt events
195 * @nr_retries: Total number of hrtimer interrupt retries
196 * @nr_hangs: Total number of hrtimer interrupt hangs
197 * @max_hang_time: Maximum time spent in hrtimer_interrupt
198 * @softirq_expiry_lock: Lock which is taken while softirq based hrtimer are
199 * expired
200 * @timer_waiters: A hrtimer_cancel() invocation waits for the timer
201 * callback to finish.
202 * @expires_next: absolute time of the next event, is required for remote
203 * hrtimer enqueue; it is the total first expiry time (hard
204 * and soft hrtimer are taken into account)
205 * @next_timer: Pointer to the first expiring timer
206 * @softirq_expires_next: Time to check, if soft queues needs also to be expired
207 * @softirq_next_timer: Pointer to the first expiring softirq based timer
208 * @clock_base: array of clock bases for this cpu
209 *
210 * Note: next_timer is just an optimization for __remove_hrtimer().
211 * Do not dereference the pointer because it is not reliable on
212 * cross cpu removals.
213 */
214struct hrtimer_cpu_base {
215 raw_spinlock_t lock;
216 unsigned int cpu;
217 unsigned int active_bases;
218 unsigned int clock_was_set_seq;
219 unsigned int hres_active : 1,
220 in_hrtirq : 1,
221 hang_detected : 1,
222 softirq_activated : 1;
223#ifdef CONFIG_HIGH_RES_TIMERS
224 unsigned int nr_events;
225 unsigned short nr_retries;
226 unsigned short nr_hangs;
227 unsigned int max_hang_time;
228#endif
229#ifdef CONFIG_PREEMPT_RT
230 spinlock_t softirq_expiry_lock;
231 atomic_t timer_waiters;
232#endif
233 ktime_t expires_next;
234 struct hrtimer *next_timer;
235 ktime_t softirq_expires_next;
236 struct hrtimer *softirq_next_timer;
237 struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
238} ____cacheline_aligned;
239
240static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
241{
242 timer->node.expires = time;
243 timer->_softexpires = time;
244}
245
246static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
247{
248 timer->_softexpires = time;
249 timer->node.expires = ktime_add_safe(time, delta);
250}
251
252static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, u64 delta)
253{
254 timer->_softexpires = time;
255 timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
256}
257
258static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
259{
260 timer->node.expires = tv64;
261 timer->_softexpires = tv64;
262}
263
264static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
265{
266 timer->node.expires = ktime_add_safe(timer->node.expires, time);
267 timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
268}
269
270static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
271{
272 timer->node.expires = ktime_add_ns(timer->node.expires, ns);
273 timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
274}
275
276static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
277{
278 return timer->node.expires;
279}
280
281static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
282{
283 return timer->_softexpires;
284}
285
286static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
287{
288 return timer->node.expires;
289}
290static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
291{
292 return timer->_softexpires;
293}
294
295static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
296{
297 return ktime_to_ns(timer->node.expires);
298}
299
300static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
301{
302 return ktime_sub(timer->node.expires, timer->base->get_time());
303}
304
305static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
306{
307 return timer->base->get_time();
308}
309
310static inline int hrtimer_is_hres_active(struct hrtimer *timer)
311{
312 return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
313 timer->base->cpu_base->hres_active : 0;
314}
315
316#ifdef CONFIG_HIGH_RES_TIMERS
317struct clock_event_device;
318
319extern void hrtimer_interrupt(struct clock_event_device *dev);
320
321extern unsigned int hrtimer_resolution;
322
323#else
324
325#define hrtimer_resolution (unsigned int)LOW_RES_NSEC
326
327#endif
328
329static inline ktime_t
330__hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now)
331{
332 ktime_t rem = ktime_sub(timer->node.expires, now);
333
334 /*
335 * Adjust relative timers for the extra we added in
336 * hrtimer_start_range_ns() to prevent short timeouts.
337 */
338 if (IS_ENABLED(CONFIG_TIME_LOW_RES) && timer->is_rel)
339 rem -= hrtimer_resolution;
340 return rem;
341}
342
343static inline ktime_t
344hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
345{
346 return __hrtimer_expires_remaining_adjusted(timer,
347 timer->base->get_time());
348}
349
350#ifdef CONFIG_TIMERFD
351extern void timerfd_clock_was_set(void);
352extern void timerfd_resume(void);
353#else
354static inline void timerfd_clock_was_set(void) { }
355static inline void timerfd_resume(void) { }
356#endif
357
358DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
359
360#ifdef CONFIG_PREEMPT_RT
361void hrtimer_cancel_wait_running(const struct hrtimer *timer);
362#else
363static inline void hrtimer_cancel_wait_running(struct hrtimer *timer)
364{
365 cpu_relax();
366}
367#endif
368
369/* Exported timer functions: */
370
371/* Initialize timers: */
372extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
373 enum hrtimer_mode mode);
374extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
375 enum hrtimer_mode mode);
376
377#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
378extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
379 enum hrtimer_mode mode);
380extern void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
381 clockid_t clock_id,
382 enum hrtimer_mode mode);
383
384extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
385#else
386static inline void hrtimer_init_on_stack(struct hrtimer *timer,
387 clockid_t which_clock,
388 enum hrtimer_mode mode)
389{
390 hrtimer_init(timer, which_clock, mode);
391}
392
393static inline void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
394 clockid_t clock_id,
395 enum hrtimer_mode mode)
396{
397 hrtimer_init_sleeper(sl, clock_id, mode);
398}
399
400static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
401#endif
402
403/* Basic timer operations: */
404extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
405 u64 range_ns, const enum hrtimer_mode mode);
406
407/**
408 * hrtimer_start - (re)start an hrtimer
409 * @timer: the timer to be added
410 * @tim: expiry time
411 * @mode: timer mode: absolute (HRTIMER_MODE_ABS) or
412 * relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
413 * softirq based mode is considered for debug purpose only!
414 */
415static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
416 const enum hrtimer_mode mode)
417{
418 hrtimer_start_range_ns(timer, tim, 0, mode);
419}
420
421extern int hrtimer_cancel(struct hrtimer *timer);
422extern int hrtimer_try_to_cancel(struct hrtimer *timer);
423
424static inline void hrtimer_start_expires(struct hrtimer *timer,
425 enum hrtimer_mode mode)
426{
427 u64 delta;
428 ktime_t soft, hard;
429 soft = hrtimer_get_softexpires(timer);
430 hard = hrtimer_get_expires(timer);
431 delta = ktime_to_ns(ktime_sub(hard, soft));
432 hrtimer_start_range_ns(timer, soft, delta, mode);
433}
434
435void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
436 enum hrtimer_mode mode);
437
438static inline void hrtimer_restart(struct hrtimer *timer)
439{
440 hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
441}
442
443/* Query timers: */
444extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);
445
446/**
447 * hrtimer_get_remaining - get remaining time for the timer
448 * @timer: the timer to read
449 */
450static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
451{
452 return __hrtimer_get_remaining(timer, false);
453}
454
455extern u64 hrtimer_get_next_event(void);
456extern u64 hrtimer_next_event_without(const struct hrtimer *exclude);
457
458extern bool hrtimer_active(const struct hrtimer *timer);
459
460/**
461 * hrtimer_is_queued - check, whether the timer is on one of the queues
462 * @timer: Timer to check
463 *
464 * Returns: True if the timer is queued, false otherwise
465 *
466 * The function can be used lockless, but it gives only a current snapshot.
467 */
468static inline bool hrtimer_is_queued(struct hrtimer *timer)
469{
470 /* The READ_ONCE pairs with the update functions of timer->state */
471 return !!(READ_ONCE(timer->state) & HRTIMER_STATE_ENQUEUED);
472}
473
474/*
475 * Helper function to check, whether the timer is running the callback
476 * function
477 */
478static inline int hrtimer_callback_running(struct hrtimer *timer)
479{
480 return timer->base->running == timer;
481}
482
483/* Forward a hrtimer so it expires after now: */
484extern u64
485hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
486
487/**
488 * hrtimer_forward_now - forward the timer expiry so it expires after now
489 * @timer: hrtimer to forward
490 * @interval: the interval to forward
491 *
492 * Forward the timer expiry so it will expire after the current time
493 * of the hrtimer clock base. Returns the number of overruns.
494 *
495 * Can be safely called from the callback function of @timer. If
496 * called from other contexts @timer must neither be enqueued nor
497 * running the callback and the caller needs to take care of
498 * serialization.
499 *
500 * Note: This only updates the timer expiry value and does not requeue
501 * the timer.
502 */
503static inline u64 hrtimer_forward_now(struct hrtimer *timer,
504 ktime_t interval)
505{
506 return hrtimer_forward(timer, timer->base->get_time(), interval);
507}
508
509/* Precise sleep: */
510
511extern int nanosleep_copyout(struct restart_block *, struct timespec64 *);
512extern long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
513 const clockid_t clockid);
514
515extern int schedule_hrtimeout_range(ktime_t *expires, u64 delta,
516 const enum hrtimer_mode mode);
517extern int schedule_hrtimeout_range_clock(ktime_t *expires,
518 u64 delta,
519 const enum hrtimer_mode mode,
520 clockid_t clock_id);
521extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
522
523/* Soft interrupt function to run the hrtimer queues: */
524extern void hrtimer_run_queues(void);
525
526/* Bootup initialization: */
527extern void __init hrtimers_init(void);
528
529/* Show pending timers: */
530extern void sysrq_timer_list_show(void);
531
532int hrtimers_prepare_cpu(unsigned int cpu);
533#ifdef CONFIG_HOTPLUG_CPU
534int hrtimers_dead_cpu(unsigned int cpu);
535#else
536#define hrtimers_dead_cpu NULL
537#endif
538
539#endif
540

source code of linux/include/linux/hrtimer.h