summaryrefslogtreecommitdiff
path: root/include/linux/hrtimer.h
blob: 0ee140176f102f4eed0986f6eebb41c9ec839870 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
// SPDX-License-Identifier: GPL-2.0
/*
 *  hrtimers - High-resolution kernel timers
 *
 *   Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
 *   Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
 *
 *  data type definitions, declarations, prototypes
 *
 *  Started by: Thomas Gleixner and Ingo Molnar
 */
#ifndef _LINUX_HRTIMER_H
#define _LINUX_HRTIMER_H

#include <linux/hrtimer_defs.h>
#include <linux/rbtree.h>
#include <linux/init.h>
#include <linux/list.h>
#include <linux/percpu.h>
#include <linux/seqlock.h>
#include <linux/timer.h>
#include <linux/timerqueue.h>

struct hrtimer_clock_base;
struct hrtimer_cpu_base;

/*
 * Mode arguments of xxx_hrtimer functions:
 *
 * HRTIMER_MODE_ABS		- Time value is absolute
 * HRTIMER_MODE_REL		- Time value is relative to now
 * HRTIMER_MODE_PINNED		- Timer is bound to CPU (is only considered
 *				  when starting the timer)
 * HRTIMER_MODE_SOFT		- Timer callback function will be executed in
 *				  soft irq context
 * HRTIMER_MODE_HARD		- Timer callback function will be executed in
 *				  hard irq context even on PREEMPT_RT.
 */
enum hrtimer_mode {
	HRTIMER_MODE_ABS	= 0x00,
	HRTIMER_MODE_REL	= 0x01,
	HRTIMER_MODE_PINNED	= 0x02,
	HRTIMER_MODE_SOFT	= 0x04,
	HRTIMER_MODE_HARD	= 0x08,

	HRTIMER_MODE_ABS_PINNED = HRTIMER_MODE_ABS | HRTIMER_MODE_PINNED,
	HRTIMER_MODE_REL_PINNED = HRTIMER_MODE_REL | HRTIMER_MODE_PINNED,

	HRTIMER_MODE_ABS_SOFT	= HRTIMER_MODE_ABS | HRTIMER_MODE_SOFT,
	HRTIMER_MODE_REL_SOFT	= HRTIMER_MODE_REL | HRTIMER_MODE_SOFT,

	HRTIMER_MODE_ABS_PINNED_SOFT = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_SOFT,
	HRTIMER_MODE_REL_PINNED_SOFT = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_SOFT,

	HRTIMER_MODE_ABS_HARD	= HRTIMER_MODE_ABS | HRTIMER_MODE_HARD,
	HRTIMER_MODE_REL_HARD	= HRTIMER_MODE_REL | HRTIMER_MODE_HARD,

	HRTIMER_MODE_ABS_PINNED_HARD = HRTIMER_MODE_ABS_PINNED | HRTIMER_MODE_HARD,
	HRTIMER_MODE_REL_PINNED_HARD = HRTIMER_MODE_REL_PINNED | HRTIMER_MODE_HARD,
};

/*
 * Return values for the callback function
 */
enum hrtimer_restart {
	HRTIMER_NORESTART,	/* Timer is not restarted */
	HRTIMER_RESTART,	/* Timer must be restarted */
};

/*
 * Values to track state of the timer
 *
 * Possible states:
 *
 * 0x00		inactive
 * 0x01		enqueued into rbtree
 *
 * The callback state is not part of the timer->state because clearing it would
 * mean touching the timer after the callback, this makes it impossible to free
 * the timer from the callback function.
 *
 * Therefore we track the callback state in:
 *
 *	timer->base->cpu_base->running == timer
 *
 * On SMP it is possible to have a "callback function running and enqueued"
 * status. It happens for example when a posix timer expired and the callback
 * queued a signal. Between dropping the lock which protects the posix timer
 * and reacquiring the base lock of the hrtimer, another CPU can deliver the
 * signal and rearm the timer.
 *
 * All state transitions are protected by cpu_base->lock.
 */
#define HRTIMER_STATE_INACTIVE	0x00
#define HRTIMER_STATE_ENQUEUED	0x01

/**
 * struct hrtimer - the basic hrtimer structure
 * @node:	timerqueue node, which also manages node.expires,
 *		the absolute expiry time in the hrtimers internal
 *		representation. The time is related to the clock on
 *		which the timer is based. Is setup by adding
 *		slack to the _softexpires value. For non range timers
 *		identical to _softexpires.
 * @_softexpires: the absolute earliest expiry time of the hrtimer.
 *		The time which was given as expiry time when the timer
 *		was armed.
 * @function:	timer expiry callback function
 * @base:	pointer to the timer base (per cpu and per clock)
 * @state:	state information (See bit values above)
 * @is_rel:	Set if the timer was armed relative
 * @is_soft:	Set if hrtimer will be expired in soft interrupt context.
 * @is_hard:	Set if hrtimer will be expired in hard interrupt context
 *		even on RT.
 *
 * The hrtimer structure must be initialized by hrtimer_init()
 */
struct hrtimer {
	struct timerqueue_node		node;
	ktime_t				_softexpires;
	enum hrtimer_restart		(*function)(struct hrtimer *);
	struct hrtimer_clock_base	*base;
	u8				state;
	u8				is_rel;
	u8				is_soft;
	u8				is_hard;
};

/**
 * struct hrtimer_sleeper - simple sleeper structure
 * @timer:	embedded timer structure
 * @task:	task to wake up
 *
 * task is set to NULL, when the timer expires.
 */
struct hrtimer_sleeper {
	struct hrtimer timer;
	struct task_struct *task;
};

#ifdef CONFIG_64BIT
# define __hrtimer_clock_base_align	____cacheline_aligned
#else
# define __hrtimer_clock_base_align
#endif

/**
 * struct hrtimer_clock_base - the timer base for a specific clock
 * @cpu_base:		per cpu clock base
 * @index:		clock type index for per_cpu support when moving a
 *			timer to a base on another cpu.
 * @clockid:		clock id for per_cpu support
 * @seq:		seqcount around __run_hrtimer
 * @running:		pointer to the currently running hrtimer
 * @active:		red black tree root node for the active timers
 * @get_time:		function to retrieve the current time of the clock
 * @offset:		offset of this clock to the monotonic base
 */
struct hrtimer_clock_base {
	struct hrtimer_cpu_base	*cpu_base;
	unsigned int		index;
	clockid_t		clockid;
	seqcount_raw_spinlock_t	seq;
	struct hrtimer		*running;
	struct timerqueue_head	active;
	ktime_t			(*get_time)(void);
	ktime_t			offset;
} __hrtimer_clock_base_align;

enum  hrtimer_base_type {
	HRTIMER_BASE_MONOTONIC,
	HRTIMER_BASE_REALTIME,
	HRTIMER_BASE_BOOTTIME,
	HRTIMER_BASE_TAI,
	HRTIMER_BASE_MONOTONIC_SOFT,
	HRTIMER_BASE_REALTIME_SOFT,
	HRTIMER_BASE_BOOTTIME_SOFT,
	HRTIMER_BASE_TAI_SOFT,
	HRTIMER_MAX_CLOCK_BASES,
};

/**
 * struct hrtimer_cpu_base - the per cpu clock bases
 * @lock:		lock protecting the base and associated clock bases
 *			and timers
 * @cpu:		cpu number
 * @active_bases:	Bitfield to mark bases with active timers
 * @clock_was_set_seq:	Sequence counter of clock was set events
 * @hres_active:	State of high resolution mode
 * @in_hrtirq:		hrtimer_interrupt() is currently executing
 * @hang_detected:	The last hrtimer interrupt detected a hang
 * @softirq_activated:	displays, if the softirq is raised - update of softirq
 *			related settings is not required then.
 * @nr_events:		Total number of hrtimer interrupt events
 * @nr_retries:		Total number of hrtimer interrupt retries
 * @nr_hangs:		Total number of hrtimer interrupt hangs
 * @max_hang_time:	Maximum time spent in hrtimer_interrupt
 * @softirq_expiry_lock: Lock which is taken while softirq based hrtimer are
 *			 expired
 * @timer_waiters:	A hrtimer_cancel() invocation waits for the timer
 *			callback to finish.
 * @expires_next:	absolute time of the next event, is required for remote
 *			hrtimer enqueue; it is the total first expiry time (hard
 *			and soft hrtimer are taken into account)
 * @next_timer:		Pointer to the first expiring timer
 * @softirq_expires_next: Time to check, if soft queues needs also to be expired
 * @softirq_next_timer: Pointer to the first expiring softirq based timer
 * @clock_base:		array of clock bases for this cpu
 *
 * Note: next_timer is just an optimization for __remove_hrtimer().
 *	 Do not dereference the pointer because it is not reliable on
 *	 cross cpu removals.
 */
struct hrtimer_cpu_base {
	raw_spinlock_t			lock;
	unsigned int			cpu;
	unsigned int			active_bases;
	unsigned int			clock_was_set_seq;
	unsigned int			hres_active		: 1,
					in_hrtirq		: 1,
					hang_detected		: 1,
					softirq_activated       : 1;
#ifdef CONFIG_HIGH_RES_TIMERS
	unsigned int			nr_events;
	unsigned short			nr_retries;
	unsigned short			nr_hangs;
	unsigned int			max_hang_time;
#endif
#ifdef CONFIG_PREEMPT_RT
	spinlock_t			softirq_expiry_lock;
	atomic_t			timer_waiters;
#endif
	ktime_t				expires_next;
	struct hrtimer			*next_timer;
	ktime_t				softirq_expires_next;
	struct hrtimer			*softirq_next_timer;
	struct hrtimer_clock_base	clock_base[HRTIMER_MAX_CLOCK_BASES];
} ____cacheline_aligned;

static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
{
	timer->node.expires = time;
	timer->_softexpires = time;
}

static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
{
	timer->_softexpires = time;
	timer->node.expires = ktime_add_safe(time, delta);
}

static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, u64 delta)
{
	timer->_softexpires = time;
	timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
}

static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
{
	timer->node.expires = tv64;
	timer->_softexpires = tv64;
}

static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
{
	timer->node.expires = ktime_add_safe(timer->node.expires, time);
	timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
}

static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
{
	timer->node.expires = ktime_add_ns(timer->node.expires, ns);
	timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
}

static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
{
	return timer->node.expires;
}

static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
{
	return timer->_softexpires;
}

static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
{
	return timer->node.expires;
}
static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
{
	return timer->_softexpires;
}

static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
{
	return ktime_to_ns(timer->node.expires);
}

static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
{
	return ktime_sub(timer->node.expires, timer->base->get_time());
}

static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
{
	return timer->base->get_time();
}

static inline int hrtimer_is_hres_active(struct hrtimer *timer)
{
	return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
		timer->base->cpu_base->hres_active : 0;
}

#ifdef CONFIG_HIGH_RES_TIMERS
struct clock_event_device;

extern void hrtimer_interrupt(struct clock_event_device *dev);

extern unsigned int hrtimer_resolution;

#else

#define hrtimer_resolution	(unsigned int)LOW_RES_NSEC

#endif

static inline ktime_t
__hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now)
{
	ktime_t rem = ktime_sub(timer->node.expires, now);

	/*
	 * Adjust relative timers for the extra we added in
	 * hrtimer_start_range_ns() to prevent short timeouts.
	 */
	if (IS_ENABLED(CONFIG_TIME_LOW_RES) && timer->is_rel)
		rem -= hrtimer_resolution;
	return rem;
}

static inline ktime_t
hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
{
	return __hrtimer_expires_remaining_adjusted(timer,
						    timer->base->get_time());
}

#ifdef CONFIG_TIMERFD
extern void timerfd_clock_was_set(void);
extern void timerfd_resume(void);
#else
static inline void timerfd_clock_was_set(void) { }
static inline void timerfd_resume(void) { }
#endif

DECLARE_PER_CPU(struct tick_device, tick_cpu_device);

#ifdef CONFIG_PREEMPT_RT
void hrtimer_cancel_wait_running(const struct hrtimer *timer);
#else
static inline void hrtimer_cancel_wait_running(struct hrtimer *timer)
{
	cpu_relax();
}
#endif

/* Exported timer functions: */

/* Initialize timers: */
extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
			 enum hrtimer_mode mode);
extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
				 enum hrtimer_mode mode);

#ifdef CONFIG_DEBUG_OBJECTS_TIMERS
extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
				  enum hrtimer_mode mode);
extern void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
					  clockid_t clock_id,
					  enum hrtimer_mode mode);

extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
#else
static inline void hrtimer_init_on_stack(struct hrtimer *timer,
					 clockid_t which_clock,
					 enum hrtimer_mode mode)
{
	hrtimer_init(timer, which_clock, mode);
}

static inline void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
						 clockid_t clock_id,
						 enum hrtimer_mode mode)
{
	hrtimer_init_sleeper(sl, clock_id, mode);
}

static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
#endif

/* Basic timer operations: */
extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
				   u64 range_ns, const enum hrtimer_mode mode);

/**
 * hrtimer_start - (re)start an hrtimer
 * @timer:	the timer to be added
 * @tim:	expiry time
 * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
 *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
 *		softirq based mode is considered for debug purpose only!
 */
static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
				 const enum hrtimer_mode mode)
{
	hrtimer_start_range_ns(timer, tim, 0, mode);
}

extern int hrtimer_cancel(struct hrtimer *timer);
extern int hrtimer_try_to_cancel(struct hrtimer *timer);

static inline void hrtimer_start_expires(struct hrtimer *timer,
					 enum hrtimer_mode mode)
{
	u64 delta;
	ktime_t soft, hard;
	soft = hrtimer_get_softexpires(timer);
	hard = hrtimer_get_expires(timer);
	delta = ktime_to_ns(ktime_sub(hard, soft));
	hrtimer_start_range_ns(timer, soft, delta, mode);
}

void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
				   enum hrtimer_mode mode);

static inline void hrtimer_restart(struct hrtimer *timer)
{
	hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
}

/* Query timers: */
extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);

/**
 * hrtimer_get_remaining - get remaining time for the timer
 * @timer:	the timer to read
 */
static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
{
	return __hrtimer_get_remaining(timer, false);
}

extern u64 hrtimer_get_next_event(void);
extern u64 hrtimer_next_event_without(const struct hrtimer *exclude);

extern bool hrtimer_active(const struct hrtimer *timer);

/**
 * hrtimer_is_queued - check, whether the timer is on one of the queues
 * @timer:	Timer to check
 *
 * Returns: True if the timer is queued, false otherwise
 *
 * The function can be used lockless, but it gives only a current snapshot.
 */
static inline bool hrtimer_is_queued(struct hrtimer *timer)
{
	/* The READ_ONCE pairs with the update functions of timer->state */
	return !!(READ_ONCE(timer->state) & HRTIMER_STATE_ENQUEUED);
}

/*
 * Helper function to check, whether the timer is running the callback
 * function
 */
static inline int hrtimer_callback_running(struct hrtimer *timer)
{
	return timer->base->running == timer;
}

/* Forward a hrtimer so it expires after now: */
extern u64
hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);

/**
 * hrtimer_forward_now - forward the timer expiry so it expires after now
 * @timer:	hrtimer to forward
 * @interval:	the interval to forward
 *
 * Forward the timer expiry so it will expire after the current time
 * of the hrtimer clock base. Returns the number of overruns.
 *
 * Can be safely called from the callback function of @timer. If
 * called from other contexts @timer must neither be enqueued nor
 * running the callback and the caller needs to take care of
 * serialization.
 *
 * Note: This only updates the timer expiry value and does not requeue
 * the timer.
 */
static inline u64 hrtimer_forward_now(struct hrtimer *timer,
				      ktime_t interval)
{
	return hrtimer_forward(timer, timer->base->get_time(), interval);
}

/* Precise sleep: */

extern int nanosleep_copyout(struct restart_block *, struct timespec64 *);
extern long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
			      const clockid_t clockid);

extern int schedule_hrtimeout_range(ktime_t *expires, u64 delta,
				    const enum hrtimer_mode mode);
extern int schedule_hrtimeout_range_clock(ktime_t *expires,
					  u64 delta,
					  const enum hrtimer_mode mode,
					  clockid_t clock_id);
extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);

/* Soft interrupt function to run the hrtimer queues: */
extern void hrtimer_run_queues(void);

/* Bootup initialization: */
extern void __init hrtimers_init(void);

/* Show pending timers: */
extern void sysrq_timer_list_show(void);

int hrtimers_prepare_cpu(unsigned int cpu);
#ifdef CONFIG_HOTPLUG_CPU
int hrtimers_dead_cpu(unsigned int cpu);
#else
#define hrtimers_dead_cpu	NULL
#endif

#endif