hrtimer.h

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 *  hrtimers - High-resolution kernel timers
  4 *
  5 *   Copyright(C) 2005, Linutronix GmbH, Thomas Gleixner <tglx@kernel.org>
  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 */
 35enum 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 */
 92struct hrtimer_sleeper {
 93	struct hrtimer timer;
 94	struct task_struct *task;
 95};
 96
 97static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
 98{
 99	timer->node.expires = time;
100	timer->_softexpires = time;
101}
102
103static 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
109static 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
115static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
116{
117	timer->node.expires = tv64;
118	timer->_softexpires = tv64;
119}
120
121static 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
127static 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
133static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
134{
135	return timer->node.expires;
136}
137
138static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
139{
140	return timer->_softexpires;
141}
142
143static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
144{
145	return timer->node.expires;
146}
147static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
148{
149	return timer->_softexpires;
150}
151
152static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
153{
154	return ktime_to_ns(timer->node.expires);
155}
156
157ktime_t hrtimer_cb_get_time(const struct hrtimer *timer);
158
159static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
160{
161	return ktime_sub(timer->node.expires, hrtimer_cb_get_time(timer));
162}
163
164static inline int hrtimer_is_hres_active(struct hrtimer *timer)
165{
166	return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
167		timer->base->cpu_base->hres_active : 0;
168}
169
170#ifdef CONFIG_HIGH_RES_TIMERS
171struct clock_event_device;
172
173extern void hrtimer_interrupt(struct clock_event_device *dev);
174
175extern unsigned int hrtimer_resolution;
176
177#else
178
179#define hrtimer_resolution	(unsigned int)LOW_RES_NSEC
180
181#endif
182
183static inline ktime_t
184__hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now)
185{
186	ktime_t rem = ktime_sub(timer->node.expires, now);
187
188	/*
189	 * Adjust relative timers for the extra we added in
190	 * hrtimer_start_range_ns() to prevent short timeouts.
191	 */
192	if (IS_ENABLED(CONFIG_TIME_LOW_RES) && timer->is_rel)
193		rem -= hrtimer_resolution;
194	return rem;
195}
196
197static inline ktime_t
198hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
199{
200	return __hrtimer_expires_remaining_adjusted(timer, hrtimer_cb_get_time(timer));
201}
202
203#ifdef CONFIG_TIMERFD
204extern void timerfd_clock_was_set(void);
205extern void timerfd_resume(void);
206#else
207static inline void timerfd_clock_was_set(void) { }
208static inline void timerfd_resume(void) { }
209#endif
210
211DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
212
213#ifdef CONFIG_PREEMPT_RT
214void hrtimer_cancel_wait_running(const struct hrtimer *timer);
215#else
216static inline void hrtimer_cancel_wait_running(struct hrtimer *timer)
217{
218	cpu_relax();
219}
220#endif
221
222static inline enum hrtimer_restart hrtimer_dummy_timeout(struct hrtimer *unused)
223{
224	return HRTIMER_NORESTART;
225}
226
227/* Exported timer functions: */
228
229/* Initialize timers: */
230extern void hrtimer_setup(struct hrtimer *timer, enum hrtimer_restart (*function)(struct hrtimer *),
231			  clockid_t clock_id, enum hrtimer_mode mode);
232extern void hrtimer_setup_on_stack(struct hrtimer *timer,
233				   enum hrtimer_restart (*function)(struct hrtimer *),
234				   clockid_t clock_id, enum hrtimer_mode mode);
235extern void hrtimer_setup_sleeper_on_stack(struct hrtimer_sleeper *sl, clockid_t clock_id,
236					   enum hrtimer_mode mode);
237
238#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
239extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
240#else
241static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
242#endif
243
244/* Basic timer operations: */
245extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
246				   u64 range_ns, const enum hrtimer_mode mode);
247
248/**
249 * hrtimer_start - (re)start an hrtimer
250 * @timer:	the timer to be added
251 * @tim:	expiry time
252 * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
253 *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
254 *		softirq based mode is considered for debug purpose only!
255 */
256static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
257				 const enum hrtimer_mode mode)
258{
259	hrtimer_start_range_ns(timer, tim, 0, mode);
260}
261
262extern int hrtimer_cancel(struct hrtimer *timer);
263extern int hrtimer_try_to_cancel(struct hrtimer *timer);
264
265static inline void hrtimer_start_expires(struct hrtimer *timer,
266					 enum hrtimer_mode mode)
267{
268	u64 delta;
269	ktime_t soft, hard;
270	soft = hrtimer_get_softexpires(timer);
271	hard = hrtimer_get_expires(timer);
272	delta = ktime_to_ns(ktime_sub(hard, soft));
273	hrtimer_start_range_ns(timer, soft, delta, mode);
274}
275
276void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
277				   enum hrtimer_mode mode);
278
279static inline void hrtimer_restart(struct hrtimer *timer)
280{
281	hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
282}
283
284/* Query timers: */
285extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);
286
287/**
288 * hrtimer_get_remaining - get remaining time for the timer
289 * @timer:	the timer to read
290 */
291static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
292{
293	return __hrtimer_get_remaining(timer, false);
294}
295
296extern u64 hrtimer_get_next_event(void);
297extern u64 hrtimer_next_event_without(const struct hrtimer *exclude);
298
299extern bool hrtimer_active(const struct hrtimer *timer);
300
301/**
302 * hrtimer_is_queued - check, whether the timer is on one of the queues
303 * @timer:	Timer to check
304 *
305 * Returns: True if the timer is queued, false otherwise
306 *
307 * The function can be used lockless, but it gives only a current snapshot.
308 */
309static inline bool hrtimer_is_queued(struct hrtimer *timer)
310{
311	/* The READ_ONCE pairs with the update functions of timer->state */
312	return !!(READ_ONCE(timer->state) & HRTIMER_STATE_ENQUEUED);
313}
314
315/*
316 * Helper function to check, whether the timer is running the callback
317 * function
318 */
319static inline int hrtimer_callback_running(struct hrtimer *timer)
320{
321	return timer->base->running == timer;
322}
323
324/**
325 * hrtimer_update_function - Update the timer's callback function
326 * @timer:	Timer to update
327 * @function:	New callback function
328 *
329 * Only safe to call if the timer is not enqueued. Can be called in the callback function if the
330 * timer is not enqueued at the same time (see the comments above HRTIMER_STATE_ENQUEUED).
331 */
332static inline void hrtimer_update_function(struct hrtimer *timer,
333					   enum hrtimer_restart (*function)(struct hrtimer *))
334{
335#ifdef CONFIG_PROVE_LOCKING
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#endif
344	ACCESS_PRIVATE(timer, function) = function;
345}
346
347/* Forward a hrtimer so it expires after now: */
348extern u64
349hrtimer_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 */
359static inline u64 hrtimer_forward_now(struct hrtimer *timer,
360				      ktime_t interval)
361{
362	return hrtimer_forward(timer, hrtimer_cb_get_time(timer), interval);
363}
364
365/* Precise sleep: */
366
367extern int nanosleep_copyout(struct restart_block *, struct timespec64 *);
368extern long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
369			      const clockid_t clockid);
370
371extern int schedule_hrtimeout_range(ktime_t *expires, u64 delta,
372				    const enum hrtimer_mode mode);
373extern int schedule_hrtimeout_range_clock(ktime_t *expires,
374					  u64 delta,
375					  const enum hrtimer_mode mode,
376					  clockid_t clock_id);
377extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
378
379/* Soft interrupt function to run the hrtimer queues: */
380extern void hrtimer_run_queues(void);
381
382/* Bootup initialization: */
383extern void __init hrtimers_init(void);
384
385/* Show pending timers: */
386extern void sysrq_timer_list_show(void);
387
388int hrtimers_prepare_cpu(unsigned int cpu);
389int hrtimers_cpu_starting(unsigned int cpu);
390#ifdef CONFIG_HOTPLUG_CPU
391int hrtimers_cpu_dying(unsigned int cpu);
392#else
393#define hrtimers_cpu_dying	NULL
394#endif
395
396#endif