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 
24 struct hrtimer_clock_base;
25 struct 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  */
39 enum 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  */
65 enum 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  */
118 struct 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  */
136 struct 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  */
159 struct 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 
170 enum  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  * @online:		CPU is online from an hrtimers point of view
201  * @timer_waiters:	A hrtimer_cancel() invocation waits for the timer
202  *			callback to finish.
203  * @expires_next:	absolute time of the next event, is required for remote
204  *			hrtimer enqueue; it is the total first expiry time (hard
205  *			and soft hrtimer are taken into account)
206  * @next_timer:		Pointer to the first expiring timer
207  * @softirq_expires_next: Time to check, if soft queues needs also to be expired
208  * @softirq_next_timer: Pointer to the first expiring softirq based timer
209  * @clock_base:		array of clock bases for this cpu
210  *
211  * Note: next_timer is just an optimization for __remove_hrtimer().
212  *	 Do not dereference the pointer because it is not reliable on
213  *	 cross cpu removals.
214  */
215 struct hrtimer_cpu_base {
216 	raw_spinlock_t			lock;
217 	unsigned int			cpu;
218 	unsigned int			active_bases;
219 	unsigned int			clock_was_set_seq;
220 	unsigned int			hres_active		: 1,
221 					in_hrtirq		: 1,
222 					hang_detected		: 1,
223 					softirq_activated       : 1,
224 					online			: 1;
225 #ifdef CONFIG_HIGH_RES_TIMERS
226 	unsigned int			nr_events;
227 	unsigned short			nr_retries;
228 	unsigned short			nr_hangs;
229 	unsigned int			max_hang_time;
230 #endif
231 #ifdef CONFIG_PREEMPT_RT
232 	spinlock_t			softirq_expiry_lock;
233 	atomic_t			timer_waiters;
234 #endif
235 	ktime_t				expires_next;
236 	struct hrtimer			*next_timer;
237 	ktime_t				softirq_expires_next;
238 	struct hrtimer			*softirq_next_timer;
239 	struct hrtimer_clock_base	clock_base[HRTIMER_MAX_CLOCK_BASES];
240 } ____cacheline_aligned;
241 
hrtimer_set_expires(struct hrtimer * timer,ktime_t time)242 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
243 {
244 	timer->node.expires = time;
245 	timer->_softexpires = time;
246 }
247 
hrtimer_set_expires_range(struct hrtimer * timer,ktime_t time,ktime_t delta)248 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
249 {
250 	timer->_softexpires = time;
251 	timer->node.expires = ktime_add_safe(time, delta);
252 }
253 
hrtimer_set_expires_range_ns(struct hrtimer * timer,ktime_t time,u64 delta)254 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, u64 delta)
255 {
256 	timer->_softexpires = time;
257 	timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
258 }
259 
hrtimer_set_expires_tv64(struct hrtimer * timer,s64 tv64)260 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
261 {
262 	timer->node.expires = tv64;
263 	timer->_softexpires = tv64;
264 }
265 
hrtimer_add_expires(struct hrtimer * timer,ktime_t time)266 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
267 {
268 	timer->node.expires = ktime_add_safe(timer->node.expires, time);
269 	timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
270 }
271 
hrtimer_add_expires_ns(struct hrtimer * timer,u64 ns)272 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
273 {
274 	timer->node.expires = ktime_add_ns(timer->node.expires, ns);
275 	timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
276 }
277 
hrtimer_get_expires(const struct hrtimer * timer)278 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
279 {
280 	return timer->node.expires;
281 }
282 
hrtimer_get_softexpires(const struct hrtimer * timer)283 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
284 {
285 	return timer->_softexpires;
286 }
287 
hrtimer_get_expires_tv64(const struct hrtimer * timer)288 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
289 {
290 	return timer->node.expires;
291 }
hrtimer_get_softexpires_tv64(const struct hrtimer * timer)292 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
293 {
294 	return timer->_softexpires;
295 }
296 
hrtimer_get_expires_ns(const struct hrtimer * timer)297 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
298 {
299 	return ktime_to_ns(timer->node.expires);
300 }
301 
hrtimer_expires_remaining(const struct hrtimer * timer)302 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
303 {
304 	return ktime_sub(timer->node.expires, timer->base->get_time());
305 }
306 
hrtimer_cb_get_time(struct hrtimer * timer)307 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
308 {
309 	return timer->base->get_time();
310 }
311 
hrtimer_is_hres_active(struct hrtimer * timer)312 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
313 {
314 	return IS_ENABLED(CONFIG_HIGH_RES_TIMERS) ?
315 		timer->base->cpu_base->hres_active : 0;
316 }
317 
318 #ifdef CONFIG_HIGH_RES_TIMERS
319 struct clock_event_device;
320 
321 extern void hrtimer_interrupt(struct clock_event_device *dev);
322 
323 extern unsigned int hrtimer_resolution;
324 
325 #else
326 
327 #define hrtimer_resolution	(unsigned int)LOW_RES_NSEC
328 
329 #endif
330 
331 static inline ktime_t
__hrtimer_expires_remaining_adjusted(const struct hrtimer * timer,ktime_t now)332 __hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now)
333 {
334 	ktime_t rem = ktime_sub(timer->node.expires, now);
335 
336 	/*
337 	 * Adjust relative timers for the extra we added in
338 	 * hrtimer_start_range_ns() to prevent short timeouts.
339 	 */
340 	if (IS_ENABLED(CONFIG_TIME_LOW_RES) && timer->is_rel)
341 		rem -= hrtimer_resolution;
342 	return rem;
343 }
344 
345 static inline ktime_t
hrtimer_expires_remaining_adjusted(const struct hrtimer * timer)346 hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
347 {
348 	return __hrtimer_expires_remaining_adjusted(timer,
349 						    timer->base->get_time());
350 }
351 
352 #ifdef CONFIG_TIMERFD
353 extern void timerfd_clock_was_set(void);
354 extern void timerfd_resume(void);
355 #else
timerfd_clock_was_set(void)356 static inline void timerfd_clock_was_set(void) { }
timerfd_resume(void)357 static inline void timerfd_resume(void) { }
358 #endif
359 
360 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
361 
362 #ifdef CONFIG_PREEMPT_RT
363 void hrtimer_cancel_wait_running(const struct hrtimer *timer);
364 #else
hrtimer_cancel_wait_running(struct hrtimer * timer)365 static inline void hrtimer_cancel_wait_running(struct hrtimer *timer)
366 {
367 	cpu_relax();
368 }
369 #endif
370 
371 /* Exported timer functions: */
372 
373 /* Initialize timers: */
374 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
375 			 enum hrtimer_mode mode);
376 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl, clockid_t clock_id,
377 				 enum hrtimer_mode mode);
378 
379 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
380 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
381 				  enum hrtimer_mode mode);
382 extern void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
383 					  clockid_t clock_id,
384 					  enum hrtimer_mode mode);
385 
386 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
387 #else
hrtimer_init_on_stack(struct hrtimer * timer,clockid_t which_clock,enum hrtimer_mode mode)388 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
389 					 clockid_t which_clock,
390 					 enum hrtimer_mode mode)
391 {
392 	hrtimer_init(timer, which_clock, mode);
393 }
394 
hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper * sl,clockid_t clock_id,enum hrtimer_mode mode)395 static inline void hrtimer_init_sleeper_on_stack(struct hrtimer_sleeper *sl,
396 						 clockid_t clock_id,
397 						 enum hrtimer_mode mode)
398 {
399 	hrtimer_init_sleeper(sl, clock_id, mode);
400 }
401 
destroy_hrtimer_on_stack(struct hrtimer * timer)402 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
403 #endif
404 
405 /* Basic timer operations: */
406 extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
407 				   u64 range_ns, const enum hrtimer_mode mode);
408 
409 /**
410  * hrtimer_start - (re)start an hrtimer
411  * @timer:	the timer to be added
412  * @tim:	expiry time
413  * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
414  *		relative (HRTIMER_MODE_REL), and pinned (HRTIMER_MODE_PINNED);
415  *		softirq based mode is considered for debug purpose only!
416  */
hrtimer_start(struct hrtimer * timer,ktime_t tim,const enum hrtimer_mode mode)417 static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
418 				 const enum hrtimer_mode mode)
419 {
420 	hrtimer_start_range_ns(timer, tim, 0, mode);
421 }
422 
423 extern int hrtimer_cancel(struct hrtimer *timer);
424 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
425 
hrtimer_start_expires(struct hrtimer * timer,enum hrtimer_mode mode)426 static inline void hrtimer_start_expires(struct hrtimer *timer,
427 					 enum hrtimer_mode mode)
428 {
429 	u64 delta;
430 	ktime_t soft, hard;
431 	soft = hrtimer_get_softexpires(timer);
432 	hard = hrtimer_get_expires(timer);
433 	delta = ktime_to_ns(ktime_sub(hard, soft));
434 	hrtimer_start_range_ns(timer, soft, delta, mode);
435 }
436 
437 void hrtimer_sleeper_start_expires(struct hrtimer_sleeper *sl,
438 				   enum hrtimer_mode mode);
439 
hrtimer_restart(struct hrtimer * timer)440 static inline void hrtimer_restart(struct hrtimer *timer)
441 {
442 	hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
443 }
444 
445 /* Query timers: */
446 extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);
447 
448 /**
449  * hrtimer_get_remaining - get remaining time for the timer
450  * @timer:	the timer to read
451  */
hrtimer_get_remaining(const struct hrtimer * timer)452 static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
453 {
454 	return __hrtimer_get_remaining(timer, false);
455 }
456 
457 extern u64 hrtimer_get_next_event(void);
458 extern u64 hrtimer_next_event_without(const struct hrtimer *exclude);
459 
460 extern bool hrtimer_active(const struct hrtimer *timer);
461 
462 /**
463  * hrtimer_is_queued - check, whether the timer is on one of the queues
464  * @timer:	Timer to check
465  *
466  * Returns: True if the timer is queued, false otherwise
467  *
468  * The function can be used lockless, but it gives only a current snapshot.
469  */
hrtimer_is_queued(struct hrtimer * timer)470 static inline bool hrtimer_is_queued(struct hrtimer *timer)
471 {
472 	/* The READ_ONCE pairs with the update functions of timer->state */
473 	return !!(READ_ONCE(timer->state) & HRTIMER_STATE_ENQUEUED);
474 }
475 
476 /*
477  * Helper function to check, whether the timer is running the callback
478  * function
479  */
hrtimer_callback_running(struct hrtimer * timer)480 static inline int hrtimer_callback_running(struct hrtimer *timer)
481 {
482 	return timer->base->running == timer;
483 }
484 
485 /* Forward a hrtimer so it expires after now: */
486 extern u64
487 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
488 
489 /**
490  * hrtimer_forward_now - forward the timer expiry so it expires after now
491  * @timer:	hrtimer to forward
492  * @interval:	the interval to forward
493  *
494  * Forward the timer expiry so it will expire after the current time
495  * of the hrtimer clock base. Returns the number of overruns.
496  *
497  * Can be safely called from the callback function of @timer. If
498  * called from other contexts @timer must neither be enqueued nor
499  * running the callback and the caller needs to take care of
500  * serialization.
501  *
502  * Note: This only updates the timer expiry value and does not requeue
503  * the timer.
504  */
hrtimer_forward_now(struct hrtimer * timer,ktime_t interval)505 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
506 				      ktime_t interval)
507 {
508 	return hrtimer_forward(timer, timer->base->get_time(), interval);
509 }
510 
511 /* Precise sleep: */
512 
513 extern int nanosleep_copyout(struct restart_block *, struct timespec64 *);
514 extern long hrtimer_nanosleep(ktime_t rqtp, const enum hrtimer_mode mode,
515 			      const clockid_t clockid);
516 
517 extern int schedule_hrtimeout_range(ktime_t *expires, u64 delta,
518 				    const enum hrtimer_mode mode);
519 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
520 					  u64 delta,
521 					  const enum hrtimer_mode mode,
522 					  clockid_t clock_id);
523 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
524 
525 /* Soft interrupt function to run the hrtimer queues: */
526 extern void hrtimer_run_queues(void);
527 
528 /* Bootup initialization: */
529 extern void __init hrtimers_init(void);
530 
531 /* Show pending timers: */
532 extern void sysrq_timer_list_show(void);
533 
534 int hrtimers_prepare_cpu(unsigned int cpu);
535 #ifdef CONFIG_HOTPLUG_CPU
536 int hrtimers_cpu_dying(unsigned int cpu);
537 #else
538 #define hrtimers_cpu_dying	NULL
539 #endif
540 
541 #endif
542