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Linux/include/linux/hrtimer.h

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  1 /*
  2  *  include/linux/hrtimer.h
  3  *
  4  *  hrtimers - High-resolution kernel timers
  5  *
  6  *   Copyright(C) 2005, Thomas Gleixner <tglx@linutronix.de>
  7  *   Copyright(C) 2005, Red Hat, Inc., Ingo Molnar
  8  *
  9  *  data type definitions, declarations, prototypes
 10  *
 11  *  Started by: Thomas Gleixner and Ingo Molnar
 12  *
 13  *  For licencing details see kernel-base/COPYING
 14  */
 15 #ifndef _LINUX_HRTIMER_H
 16 #define _LINUX_HRTIMER_H
 17 
 18 #include <linux/rbtree.h>
 19 #include <linux/ktime.h>
 20 #include <linux/init.h>
 21 #include <linux/list.h>
 22 #include <linux/wait.h>
 23 #include <linux/percpu.h>
 24 #include <linux/timer.h>
 25 #include <linux/timerqueue.h>
 26 
 27 struct hrtimer_clock_base;
 28 struct hrtimer_cpu_base;
 29 
 30 /*
 31  * Mode arguments of xxx_hrtimer functions:
 32  */
 33 enum hrtimer_mode {
 34         HRTIMER_MODE_ABS = 0x0,         /* Time value is absolute */
 35         HRTIMER_MODE_REL = 0x1,         /* Time value is relative to now */
 36         HRTIMER_MODE_PINNED = 0x02,     /* Timer is bound to CPU */
 37         HRTIMER_MODE_ABS_PINNED = 0x02,
 38         HRTIMER_MODE_REL_PINNED = 0x03,
 39 };
 40 
 41 /*
 42  * Return values for the callback function
 43  */
 44 enum hrtimer_restart {
 45         HRTIMER_NORESTART,      /* Timer is not restarted */
 46         HRTIMER_RESTART,        /* Timer must be restarted */
 47 };
 48 
 49 /*
 50  * Values to track state of the timer
 51  *
 52  * Possible states:
 53  *
 54  * 0x00         inactive
 55  * 0x01         enqueued into rbtree
 56  *
 57  * The callback state is not part of the timer->state because clearing it would
 58  * mean touching the timer after the callback, this makes it impossible to free
 59  * the timer from the callback function.
 60  *
 61  * Therefore we track the callback state in:
 62  *
 63  *      timer->base->cpu_base->running == timer
 64  *
 65  * On SMP it is possible to have a "callback function running and enqueued"
 66  * status. It happens for example when a posix timer expired and the callback
 67  * queued a signal. Between dropping the lock which protects the posix timer
 68  * and reacquiring the base lock of the hrtimer, another CPU can deliver the
 69  * signal and rearm the timer.
 70  *
 71  * All state transitions are protected by cpu_base->lock.
 72  */
 73 #define HRTIMER_STATE_INACTIVE  0x00
 74 #define HRTIMER_STATE_ENQUEUED  0x01
 75 
 76 /**
 77  * struct hrtimer - the basic hrtimer structure
 78  * @node:       timerqueue node, which also manages node.expires,
 79  *              the absolute expiry time in the hrtimers internal
 80  *              representation. The time is related to the clock on
 81  *              which the timer is based. Is setup by adding
 82  *              slack to the _softexpires value. For non range timers
 83  *              identical to _softexpires.
 84  * @_softexpires: the absolute earliest expiry time of the hrtimer.
 85  *              The time which was given as expiry time when the timer
 86  *              was armed.
 87  * @function:   timer expiry callback function
 88  * @base:       pointer to the timer base (per cpu and per clock)
 89  * @state:      state information (See bit values above)
 90  * @is_rel:     Set if the timer was armed relative
 91  * @start_pid:  timer statistics field to store the pid of the task which
 92  *              started the timer
 93  * @start_site: timer statistics field to store the site where the timer
 94  *              was started
 95  * @start_comm: timer statistics field to store the name of the process which
 96  *              started the timer
 97  *
 98  * The hrtimer structure must be initialized by hrtimer_init()
 99  */
100 struct hrtimer {
101         struct timerqueue_node          node;
102         ktime_t                         _softexpires;
103         enum hrtimer_restart            (*function)(struct hrtimer *);
104         struct hrtimer_clock_base       *base;
105         u8                              state;
106         u8                              is_rel;
107 #ifdef CONFIG_TIMER_STATS
108         int                             start_pid;
109         void                            *start_site;
110         char                            start_comm[16];
111 #endif
112 };
113 
114 /**
115  * struct hrtimer_sleeper - simple sleeper structure
116  * @timer:      embedded timer structure
117  * @task:       task to wake up
118  *
119  * task is set to NULL, when the timer expires.
120  */
121 struct hrtimer_sleeper {
122         struct hrtimer timer;
123         struct task_struct *task;
124 };
125 
126 #ifdef CONFIG_64BIT
127 # define HRTIMER_CLOCK_BASE_ALIGN       64
128 #else
129 # define HRTIMER_CLOCK_BASE_ALIGN       32
130 #endif
131 
132 /**
133  * struct hrtimer_clock_base - the timer base for a specific clock
134  * @cpu_base:           per cpu clock base
135  * @index:              clock type index for per_cpu support when moving a
136  *                      timer to a base on another cpu.
137  * @clockid:            clock id for per_cpu support
138  * @active:             red black tree root node for the active timers
139  * @get_time:           function to retrieve the current time of the clock
140  * @offset:             offset of this clock to the monotonic base
141  */
142 struct hrtimer_clock_base {
143         struct hrtimer_cpu_base *cpu_base;
144         int                     index;
145         clockid_t               clockid;
146         struct timerqueue_head  active;
147         ktime_t                 (*get_time)(void);
148         ktime_t                 offset;
149 } __attribute__((__aligned__(HRTIMER_CLOCK_BASE_ALIGN)));
150 
151 enum  hrtimer_base_type {
152         HRTIMER_BASE_MONOTONIC,
153         HRTIMER_BASE_REALTIME,
154         HRTIMER_BASE_BOOTTIME,
155         HRTIMER_BASE_TAI,
156         HRTIMER_MAX_CLOCK_BASES,
157 };
158 
159 /*
160  * struct hrtimer_cpu_base - the per cpu clock bases
161  * @lock:               lock protecting the base and associated clock bases
162  *                      and timers
163  * @seq:                seqcount around __run_hrtimer
164  * @running:            pointer to the currently running hrtimer
165  * @cpu:                cpu number
166  * @active_bases:       Bitfield to mark bases with active timers
167  * @clock_was_set_seq:  Sequence counter of clock was set events
168  * @migration_enabled:  The migration of hrtimers to other cpus is enabled
169  * @nohz_active:        The nohz functionality is enabled
170  * @expires_next:       absolute time of the next event which was scheduled
171  *                      via clock_set_next_event()
172  * @next_timer:         Pointer to the first expiring timer
173  * @in_hrtirq:          hrtimer_interrupt() is currently executing
174  * @hres_active:        State of high resolution mode
175  * @hang_detected:      The last hrtimer interrupt detected a hang
176  * @nr_events:          Total number of hrtimer interrupt events
177  * @nr_retries:         Total number of hrtimer interrupt retries
178  * @nr_hangs:           Total number of hrtimer interrupt hangs
179  * @max_hang_time:      Maximum time spent in hrtimer_interrupt
180  * @clock_base:         array of clock bases for this cpu
181  *
182  * Note: next_timer is just an optimization for __remove_hrtimer().
183  *       Do not dereference the pointer because it is not reliable on
184  *       cross cpu removals.
185  */
186 struct hrtimer_cpu_base {
187         raw_spinlock_t                  lock;
188         seqcount_t                      seq;
189         struct hrtimer                  *running;
190         unsigned int                    cpu;
191         unsigned int                    active_bases;
192         unsigned int                    clock_was_set_seq;
193         bool                            migration_enabled;
194         bool                            nohz_active;
195 #ifdef CONFIG_HIGH_RES_TIMERS
196         unsigned int                    in_hrtirq       : 1,
197                                         hres_active     : 1,
198                                         hang_detected   : 1;
199         ktime_t                         expires_next;
200         struct hrtimer                  *next_timer;
201         unsigned int                    nr_events;
202         unsigned int                    nr_retries;
203         unsigned int                    nr_hangs;
204         unsigned int                    max_hang_time;
205 #endif
206         struct hrtimer_clock_base       clock_base[HRTIMER_MAX_CLOCK_BASES];
207 } ____cacheline_aligned;
208 
209 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
210 {
211         BUILD_BUG_ON(sizeof(struct hrtimer_clock_base) > HRTIMER_CLOCK_BASE_ALIGN);
212 
213         timer->node.expires = time;
214         timer->_softexpires = time;
215 }
216 
217 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
218 {
219         timer->_softexpires = time;
220         timer->node.expires = ktime_add_safe(time, delta);
221 }
222 
223 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
224 {
225         timer->_softexpires = time;
226         timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
227 }
228 
229 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
230 {
231         timer->node.expires.tv64 = tv64;
232         timer->_softexpires.tv64 = tv64;
233 }
234 
235 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
236 {
237         timer->node.expires = ktime_add_safe(timer->node.expires, time);
238         timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
239 }
240 
241 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
242 {
243         timer->node.expires = ktime_add_ns(timer->node.expires, ns);
244         timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
245 }
246 
247 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
248 {
249         return timer->node.expires;
250 }
251 
252 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
253 {
254         return timer->_softexpires;
255 }
256 
257 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
258 {
259         return timer->node.expires.tv64;
260 }
261 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
262 {
263         return timer->_softexpires.tv64;
264 }
265 
266 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
267 {
268         return ktime_to_ns(timer->node.expires);
269 }
270 
271 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
272 {
273         return ktime_sub(timer->node.expires, timer->base->get_time());
274 }
275 
276 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
277 {
278         return timer->base->get_time();
279 }
280 
281 #ifdef CONFIG_HIGH_RES_TIMERS
282 struct clock_event_device;
283 
284 extern void hrtimer_interrupt(struct clock_event_device *dev);
285 
286 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
287 {
288         return timer->base->cpu_base->hres_active;
289 }
290 
291 extern void hrtimer_peek_ahead_timers(void);
292 
293 /*
294  * The resolution of the clocks. The resolution value is returned in
295  * the clock_getres() system call to give application programmers an
296  * idea of the (in)accuracy of timers. Timer values are rounded up to
297  * this resolution values.
298  */
299 # define HIGH_RES_NSEC          1
300 # define KTIME_HIGH_RES         (ktime_t) { .tv64 = HIGH_RES_NSEC }
301 # define MONOTONIC_RES_NSEC     HIGH_RES_NSEC
302 # define KTIME_MONOTONIC_RES    KTIME_HIGH_RES
303 
304 extern void clock_was_set_delayed(void);
305 
306 extern unsigned int hrtimer_resolution;
307 
308 #else
309 
310 # define MONOTONIC_RES_NSEC     LOW_RES_NSEC
311 # define KTIME_MONOTONIC_RES    KTIME_LOW_RES
312 
313 #define hrtimer_resolution      (unsigned int)LOW_RES_NSEC
314 
315 static inline void hrtimer_peek_ahead_timers(void) { }
316 
317 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
318 {
319         return 0;
320 }
321 
322 static inline void clock_was_set_delayed(void) { }
323 
324 #endif
325 
326 static inline ktime_t
327 __hrtimer_expires_remaining_adjusted(const struct hrtimer *timer, ktime_t now)
328 {
329         ktime_t rem = ktime_sub(timer->node.expires, now);
330 
331         /*
332          * Adjust relative timers for the extra we added in
333          * hrtimer_start_range_ns() to prevent short timeouts.
334          */
335         if (IS_ENABLED(CONFIG_TIME_LOW_RES) && timer->is_rel)
336                 rem.tv64 -= hrtimer_resolution;
337         return rem;
338 }
339 
340 static inline ktime_t
341 hrtimer_expires_remaining_adjusted(const struct hrtimer *timer)
342 {
343         return __hrtimer_expires_remaining_adjusted(timer,
344                                                     timer->base->get_time());
345 }
346 
347 extern void clock_was_set(void);
348 #ifdef CONFIG_TIMERFD
349 extern void timerfd_clock_was_set(void);
350 #else
351 static inline void timerfd_clock_was_set(void) { }
352 #endif
353 extern void hrtimers_resume(void);
354 
355 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
356 
357 
358 /* Exported timer functions: */
359 
360 /* Initialize timers: */
361 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
362                          enum hrtimer_mode mode);
363 
364 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
365 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
366                                   enum hrtimer_mode mode);
367 
368 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
369 #else
370 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
371                                          clockid_t which_clock,
372                                          enum hrtimer_mode mode)
373 {
374         hrtimer_init(timer, which_clock, mode);
375 }
376 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
377 #endif
378 
379 /* Basic timer operations: */
380 extern void hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
381                         unsigned long range_ns, const enum hrtimer_mode mode);
382 
383 /**
384  * hrtimer_start - (re)start an hrtimer on the current CPU
385  * @timer:      the timer to be added
386  * @tim:        expiry time
387  * @mode:       expiry mode: absolute (HRTIMER_MODE_ABS) or
388  *              relative (HRTIMER_MODE_REL)
389  */
390 static inline void hrtimer_start(struct hrtimer *timer, ktime_t tim,
391                                  const enum hrtimer_mode mode)
392 {
393         hrtimer_start_range_ns(timer, tim, 0, mode);
394 }
395 
396 extern int hrtimer_cancel(struct hrtimer *timer);
397 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
398 
399 static inline void hrtimer_start_expires(struct hrtimer *timer,
400                                          enum hrtimer_mode mode)
401 {
402         unsigned long delta;
403         ktime_t soft, hard;
404         soft = hrtimer_get_softexpires(timer);
405         hard = hrtimer_get_expires(timer);
406         delta = ktime_to_ns(ktime_sub(hard, soft));
407         hrtimer_start_range_ns(timer, soft, delta, mode);
408 }
409 
410 static inline void hrtimer_restart(struct hrtimer *timer)
411 {
412         hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
413 }
414 
415 /* Query timers: */
416 extern ktime_t __hrtimer_get_remaining(const struct hrtimer *timer, bool adjust);
417 
418 static inline ktime_t hrtimer_get_remaining(const struct hrtimer *timer)
419 {
420         return __hrtimer_get_remaining(timer, false);
421 }
422 
423 extern u64 hrtimer_get_next_event(void);
424 
425 extern bool hrtimer_active(const struct hrtimer *timer);
426 
427 /*
428  * Helper function to check, whether the timer is on one of the queues
429  */
430 static inline int hrtimer_is_queued(struct hrtimer *timer)
431 {
432         return timer->state & HRTIMER_STATE_ENQUEUED;
433 }
434 
435 /*
436  * Helper function to check, whether the timer is running the callback
437  * function
438  */
439 static inline int hrtimer_callback_running(struct hrtimer *timer)
440 {
441         return timer->base->cpu_base->running == timer;
442 }
443 
444 /* Forward a hrtimer so it expires after now: */
445 extern u64
446 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
447 
448 /**
449  * hrtimer_forward_now - forward the timer expiry so it expires after now
450  * @timer:      hrtimer to forward
451  * @interval:   the interval to forward
452  *
453  * Forward the timer expiry so it will expire after the current time
454  * of the hrtimer clock base. Returns the number of overruns.
455  *
456  * Can be safely called from the callback function of @timer. If
457  * called from other contexts @timer must neither be enqueued nor
458  * running the callback and the caller needs to take care of
459  * serialization.
460  *
461  * Note: This only updates the timer expiry value and does not requeue
462  * the timer.
463  */
464 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
465                                       ktime_t interval)
466 {
467         return hrtimer_forward(timer, timer->base->get_time(), interval);
468 }
469 
470 /* Precise sleep: */
471 extern long hrtimer_nanosleep(struct timespec *rqtp,
472                               struct timespec __user *rmtp,
473                               const enum hrtimer_mode mode,
474                               const clockid_t clockid);
475 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
476 
477 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
478                                  struct task_struct *tsk);
479 
480 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
481                                                 const enum hrtimer_mode mode);
482 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
483                 unsigned long delta, const enum hrtimer_mode mode, int clock);
484 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
485 
486 /* Soft interrupt function to run the hrtimer queues: */
487 extern void hrtimer_run_queues(void);
488 
489 /* Bootup initialization: */
490 extern void __init hrtimers_init(void);
491 
492 /* Show pending timers: */
493 extern void sysrq_timer_list_show(void);
494 
495 #endif
496 

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