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Linux/include/linux/hrtimer.h

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

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