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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 * 0x02 callback function running
57 * 0x04 timer is migrated to another cpu
58 *
59 * Special cases:
60 * 0x03 callback function running and enqueued
61 * (was requeued on another CPU)
62 * 0x05 timer was migrated on CPU hotunplug
63 *
64 * The "callback function running and enqueued" status is only possible on
65 * SMP. It happens for example when a posix timer expired and the callback
66 * queued a signal. Between dropping the lock which protects the posix timer
67 * and reacquiring the base lock of the hrtimer, another CPU can deliver the
68 * signal and rearm the timer. We have to preserve the callback running state,
69 * as otherwise the timer could be removed before the softirq code finishes the
70 * the handling of the timer.
71 *
72 * The HRTIMER_STATE_ENQUEUED bit is always or'ed to the current state
73 * to preserve the HRTIMER_STATE_CALLBACK in the above scenario. This
74 * also affects HRTIMER_STATE_MIGRATE where the preservation is not
75 * necessary. HRTIMER_STATE_MIGRATE is cleared after the timer is
76 * enqueued on the new cpu.
77 *
78 * All state transitions are protected by cpu_base->lock.
79 */
80 #define HRTIMER_STATE_INACTIVE 0x00
81 #define HRTIMER_STATE_ENQUEUED 0x01
82 #define HRTIMER_STATE_CALLBACK 0x02
83 #define HRTIMER_STATE_MIGRATE 0x04
84
85 /**
86 * struct hrtimer - the basic hrtimer structure
87 * @node: timerqueue node, which also manages node.expires,
88 * the absolute expiry time in the hrtimers internal
89 * representation. The time is related to the clock on
90 * which the timer is based. Is setup by adding
91 * slack to the _softexpires value. For non range timers
92 * identical to _softexpires.
93 * @_softexpires: the absolute earliest expiry time of the hrtimer.
94 * The time which was given as expiry time when the timer
95 * was armed.
96 * @function: timer expiry callback function
97 * @base: pointer to the timer base (per cpu and per clock)
98 * @state: state information (See bit values above)
99 * @start_site: timer statistics field to store the site where the timer
100 * was started
101 * @start_comm: timer statistics field to store the name of the process which
102 * started the timer
103 * @start_pid: timer statistics field to store the pid of the task which
104 * started the timer
105 *
106 * The hrtimer structure must be initialized by hrtimer_init()
107 */
108 struct hrtimer {
109 struct timerqueue_node node;
110 ktime_t _softexpires;
111 enum hrtimer_restart (*function)(struct hrtimer *);
112 struct hrtimer_clock_base *base;
113 unsigned long state;
114 #ifdef CONFIG_TIMER_STATS
115 int start_pid;
116 void *start_site;
117 char start_comm[16];
118 #endif
119 };
120
121 /**
122 * struct hrtimer_sleeper - simple sleeper structure
123 * @timer: embedded timer structure
124 * @task: task to wake up
125 *
126 * task is set to NULL, when the timer expires.
127 */
128 struct hrtimer_sleeper {
129 struct hrtimer timer;
130 struct task_struct *task;
131 };
132
133 /**
134 * struct hrtimer_clock_base - the timer base for a specific clock
135 * @cpu_base: per cpu clock base
136 * @index: clock type index for per_cpu support when moving a
137 * timer to a base on another cpu.
138 * @clockid: clock id for per_cpu support
139 * @active: red black tree root node for the active timers
140 * @resolution: the resolution of the clock, in nanoseconds
141 * @get_time: function to retrieve the current time of the clock
142 * @softirq_time: the time when running the hrtimer queue in the softirq
143 * @offset: offset of this clock to the monotonic base
144 */
145 struct hrtimer_clock_base {
146 struct hrtimer_cpu_base *cpu_base;
147 int index;
148 clockid_t clockid;
149 struct timerqueue_head active;
150 ktime_t resolution;
151 ktime_t (*get_time)(void);
152 ktime_t softirq_time;
153 ktime_t offset;
154 };
155
156 enum hrtimer_base_type {
157 HRTIMER_BASE_MONOTONIC,
158 HRTIMER_BASE_REALTIME,
159 HRTIMER_BASE_BOOTTIME,
160 HRTIMER_BASE_TAI,
161 HRTIMER_MAX_CLOCK_BASES,
162 };
163
164 /*
165 * struct hrtimer_cpu_base - the per cpu clock bases
166 * @lock: lock protecting the base and associated clock bases
167 * and timers
168 * @active_bases: Bitfield to mark bases with active timers
169 * @clock_was_set: Indicates that clock was set from irq context.
170 * @expires_next: absolute time of the next event which was scheduled
171 * via clock_set_next_event()
172 * @hres_active: State of high resolution mode
173 * @hang_detected: The last hrtimer interrupt detected a hang
174 * @nr_events: Total number of hrtimer interrupt events
175 * @nr_retries: Total number of hrtimer interrupt retries
176 * @nr_hangs: Total number of hrtimer interrupt hangs
177 * @max_hang_time: Maximum time spent in hrtimer_interrupt
178 * @clock_base: array of clock bases for this cpu
179 */
180 struct hrtimer_cpu_base {
181 raw_spinlock_t lock;
182 unsigned int active_bases;
183 unsigned int clock_was_set;
184 #ifdef CONFIG_HIGH_RES_TIMERS
185 ktime_t expires_next;
186 int hres_active;
187 int hang_detected;
188 unsigned long nr_events;
189 unsigned long nr_retries;
190 unsigned long nr_hangs;
191 ktime_t max_hang_time;
192 #endif
193 struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
194 };
195
196 static inline void hrtimer_set_expires(struct hrtimer *timer, ktime_t time)
197 {
198 timer->node.expires = time;
199 timer->_softexpires = time;
200 }
201
202 static inline void hrtimer_set_expires_range(struct hrtimer *timer, ktime_t time, ktime_t delta)
203 {
204 timer->_softexpires = time;
205 timer->node.expires = ktime_add_safe(time, delta);
206 }
207
208 static inline void hrtimer_set_expires_range_ns(struct hrtimer *timer, ktime_t time, unsigned long delta)
209 {
210 timer->_softexpires = time;
211 timer->node.expires = ktime_add_safe(time, ns_to_ktime(delta));
212 }
213
214 static inline void hrtimer_set_expires_tv64(struct hrtimer *timer, s64 tv64)
215 {
216 timer->node.expires.tv64 = tv64;
217 timer->_softexpires.tv64 = tv64;
218 }
219
220 static inline void hrtimer_add_expires(struct hrtimer *timer, ktime_t time)
221 {
222 timer->node.expires = ktime_add_safe(timer->node.expires, time);
223 timer->_softexpires = ktime_add_safe(timer->_softexpires, time);
224 }
225
226 static inline void hrtimer_add_expires_ns(struct hrtimer *timer, u64 ns)
227 {
228 timer->node.expires = ktime_add_ns(timer->node.expires, ns);
229 timer->_softexpires = ktime_add_ns(timer->_softexpires, ns);
230 }
231
232 static inline ktime_t hrtimer_get_expires(const struct hrtimer *timer)
233 {
234 return timer->node.expires;
235 }
236
237 static inline ktime_t hrtimer_get_softexpires(const struct hrtimer *timer)
238 {
239 return timer->_softexpires;
240 }
241
242 static inline s64 hrtimer_get_expires_tv64(const struct hrtimer *timer)
243 {
244 return timer->node.expires.tv64;
245 }
246 static inline s64 hrtimer_get_softexpires_tv64(const struct hrtimer *timer)
247 {
248 return timer->_softexpires.tv64;
249 }
250
251 static inline s64 hrtimer_get_expires_ns(const struct hrtimer *timer)
252 {
253 return ktime_to_ns(timer->node.expires);
254 }
255
256 static inline ktime_t hrtimer_expires_remaining(const struct hrtimer *timer)
257 {
258 return ktime_sub(timer->node.expires, timer->base->get_time());
259 }
260
261 #ifdef CONFIG_HIGH_RES_TIMERS
262 struct clock_event_device;
263
264 extern void hrtimer_interrupt(struct clock_event_device *dev);
265
266 /*
267 * In high resolution mode the time reference must be read accurate
268 */
269 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
270 {
271 return timer->base->get_time();
272 }
273
274 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
275 {
276 return timer->base->cpu_base->hres_active;
277 }
278
279 extern void hrtimer_peek_ahead_timers(void);
280
281 /*
282 * The resolution of the clocks. The resolution value is returned in
283 * the clock_getres() system call to give application programmers an
284 * idea of the (in)accuracy of timers. Timer values are rounded up to
285 * this resolution values.
286 */
287 # define HIGH_RES_NSEC 1
288 # define KTIME_HIGH_RES (ktime_t) { .tv64 = HIGH_RES_NSEC }
289 # define MONOTONIC_RES_NSEC HIGH_RES_NSEC
290 # define KTIME_MONOTONIC_RES KTIME_HIGH_RES
291
292 extern void clock_was_set_delayed(void);
293
294 #else
295
296 # define MONOTONIC_RES_NSEC LOW_RES_NSEC
297 # define KTIME_MONOTONIC_RES KTIME_LOW_RES
298
299 static inline void hrtimer_peek_ahead_timers(void) { }
300
301 /*
302 * In non high resolution mode the time reference is taken from
303 * the base softirq time variable.
304 */
305 static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
306 {
307 return timer->base->softirq_time;
308 }
309
310 static inline int hrtimer_is_hres_active(struct hrtimer *timer)
311 {
312 return 0;
313 }
314
315 static inline void clock_was_set_delayed(void) { }
316
317 #endif
318
319 extern void clock_was_set(void);
320 #ifdef CONFIG_TIMERFD
321 extern void timerfd_clock_was_set(void);
322 #else
323 static inline void timerfd_clock_was_set(void) { }
324 #endif
325 extern void hrtimers_resume(void);
326
327 extern ktime_t ktime_get(void);
328 extern ktime_t ktime_get_real(void);
329 extern ktime_t ktime_get_boottime(void);
330 extern ktime_t ktime_get_monotonic_offset(void);
331 extern ktime_t ktime_get_clocktai(void);
332 extern ktime_t ktime_get_update_offsets(ktime_t *offs_real, ktime_t *offs_boot,
333 ktime_t *offs_tai);
334
335 DECLARE_PER_CPU(struct tick_device, tick_cpu_device);
336
337
338 /* Exported timer functions: */
339
340 /* Initialize timers: */
341 extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
342 enum hrtimer_mode mode);
343
344 #ifdef CONFIG_DEBUG_OBJECTS_TIMERS
345 extern void hrtimer_init_on_stack(struct hrtimer *timer, clockid_t which_clock,
346 enum hrtimer_mode mode);
347
348 extern void destroy_hrtimer_on_stack(struct hrtimer *timer);
349 #else
350 static inline void hrtimer_init_on_stack(struct hrtimer *timer,
351 clockid_t which_clock,
352 enum hrtimer_mode mode)
353 {
354 hrtimer_init(timer, which_clock, mode);
355 }
356 static inline void destroy_hrtimer_on_stack(struct hrtimer *timer) { }
357 #endif
358
359 /* Basic timer operations: */
360 extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
361 const enum hrtimer_mode mode);
362 extern int hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
363 unsigned long range_ns, const enum hrtimer_mode mode);
364 extern int
365 __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
366 unsigned long delta_ns,
367 const enum hrtimer_mode mode, int wakeup);
368
369 extern int hrtimer_cancel(struct hrtimer *timer);
370 extern int hrtimer_try_to_cancel(struct hrtimer *timer);
371
372 static inline int hrtimer_start_expires(struct hrtimer *timer,
373 enum hrtimer_mode mode)
374 {
375 unsigned long delta;
376 ktime_t soft, hard;
377 soft = hrtimer_get_softexpires(timer);
378 hard = hrtimer_get_expires(timer);
379 delta = ktime_to_ns(ktime_sub(hard, soft));
380 return hrtimer_start_range_ns(timer, soft, delta, mode);
381 }
382
383 static inline int hrtimer_restart(struct hrtimer *timer)
384 {
385 return hrtimer_start_expires(timer, HRTIMER_MODE_ABS);
386 }
387
388 /* Query timers: */
389 extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
390 extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
391
392 extern ktime_t hrtimer_get_next_event(void);
393
394 /*
395 * A timer is active, when it is enqueued into the rbtree or the
396 * callback function is running or it's in the state of being migrated
397 * to another cpu.
398 */
399 static inline int hrtimer_active(const struct hrtimer *timer)
400 {
401 return timer->state != HRTIMER_STATE_INACTIVE;
402 }
403
404 /*
405 * Helper function to check, whether the timer is on one of the queues
406 */
407 static inline int hrtimer_is_queued(struct hrtimer *timer)
408 {
409 return timer->state & HRTIMER_STATE_ENQUEUED;
410 }
411
412 /*
413 * Helper function to check, whether the timer is running the callback
414 * function
415 */
416 static inline int hrtimer_callback_running(struct hrtimer *timer)
417 {
418 return timer->state & HRTIMER_STATE_CALLBACK;
419 }
420
421 /* Forward a hrtimer so it expires after now: */
422 extern u64
423 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
424
425 /* Forward a hrtimer so it expires after the hrtimer's current now */
426 static inline u64 hrtimer_forward_now(struct hrtimer *timer,
427 ktime_t interval)
428 {
429 return hrtimer_forward(timer, timer->base->get_time(), interval);
430 }
431
432 /* Precise sleep: */
433 extern long hrtimer_nanosleep(struct timespec *rqtp,
434 struct timespec __user *rmtp,
435 const enum hrtimer_mode mode,
436 const clockid_t clockid);
437 extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
438
439 extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
440 struct task_struct *tsk);
441
442 extern int schedule_hrtimeout_range(ktime_t *expires, unsigned long delta,
443 const enum hrtimer_mode mode);
444 extern int schedule_hrtimeout_range_clock(ktime_t *expires,
445 unsigned long delta, const enum hrtimer_mode mode, int clock);
446 extern int schedule_hrtimeout(ktime_t *expires, const enum hrtimer_mode mode);
447
448 /* Soft interrupt function to run the hrtimer queues: */
449 extern void hrtimer_run_queues(void);
450 extern void hrtimer_run_pending(void);
451
452 /* Bootup initialization: */
453 extern void __init hrtimers_init(void);
454
455 #if BITS_PER_LONG < 64
456 extern u64 ktime_divns(const ktime_t kt, s64 div);
457 #else /* BITS_PER_LONG < 64 */
458 # define ktime_divns(kt, div) (u64)((kt).tv64 / (div))
459 #endif
460
461 /* Show pending timers: */
462 extern void sysrq_timer_list_show(void);
463
464 #endif