projects/linux·blob v2.6.22-rc7 · refs

366 lines · 10.6 KiB

1/*
2 * include/linux/hrtimer.h
3 *
4 * hrtimers - High-resolution kernel timers
5 *
6 * Copyright(C) 2005, Thomas Gleixner <[email protected]>
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
24struct hrtimer_clock_base;
25struct hrtimer_cpu_base;
26
27/*
28 * Mode arguments of xxx_hrtimer functions:
29 */
30enum hrtimer_mode {
31 HRTIMER_MODE_ABS, /* Time value is absolute */
32 HRTIMER_MODE_REL, /* Time value is relative to now */
33};
34
35/*
36 * Return values for the callback function
37 */
38enum hrtimer_restart {
39 HRTIMER_NORESTART, /* Timer is not restarted */
40 HRTIMER_RESTART, /* Timer must be restarted */
41};
42
43/*
44 * hrtimer callback modes:
45 *
46 * HRTIMER_CB_SOFTIRQ: Callback must run in softirq context
47 * HRTIMER_CB_IRQSAFE: Callback may run in hardirq context
48 * HRTIMER_CB_IRQSAFE_NO_RESTART: Callback may run in hardirq context and
49 * does not restart the timer
50 * HRTIMER_CB_IRQSAFE_NO_SOFTIRQ: Callback must run in hardirq context
51 * Special mode for tick emultation
52 */
53enum hrtimer_cb_mode {
54 HRTIMER_CB_SOFTIRQ,
55 HRTIMER_CB_IRQSAFE,
56 HRTIMER_CB_IRQSAFE_NO_RESTART,
57 HRTIMER_CB_IRQSAFE_NO_SOFTIRQ,
58};
59
60/*
61 * Values to track state of the timer
62 *
63 * Possible states:
64 *
65 * 0x00 inactive
66 * 0x01 enqueued into rbtree
67 * 0x02 callback function running
68 * 0x04 callback pending (high resolution mode)
69 *
70 * Special case:
71 * 0x03 callback function running and enqueued
72 * (was requeued on another CPU)
73 * The "callback function running and enqueued" status is only possible on
74 * SMP. It happens for example when a posix timer expired and the callback
75 * queued a signal. Between dropping the lock which protects the posix timer
76 * and reacquiring the base lock of the hrtimer, another CPU can deliver the
77 * signal and rearm the timer. We have to preserve the callback running state,
78 * as otherwise the timer could be removed before the softirq code finishes the
79 * the handling of the timer.
80 *
81 * The HRTIMER_STATE_ENQUEUE bit is always or'ed to the current state to
82 * preserve the HRTIMER_STATE_CALLBACK bit in the above scenario.
83 *
84 * All state transitions are protected by cpu_base->lock.
85 */
86#define HRTIMER_STATE_INACTIVE 0x00
87#define HRTIMER_STATE_ENQUEUED 0x01
88#define HRTIMER_STATE_CALLBACK 0x02
89#define HRTIMER_STATE_PENDING 0x04
90
91/**
92 * struct hrtimer - the basic hrtimer structure
93 * @node: red black tree node for time ordered insertion
94 * @expires: the absolute expiry time in the hrtimers internal
95 * representation. The time is related to the clock on
96 * which the timer is based.
97 * @function: timer expiry callback function
98 * @base: pointer to the timer base (per cpu and per clock)
99 * @state: state information (See bit values above)
100 * @cb_mode: high resolution timer feature to select the callback execution
101 * mode
102 * @cb_entry: list head to enqueue an expired timer into the callback list
103 * @start_site: timer statistics field to store the site where the timer
104 * was started
105 * @start_comm: timer statistics field to store the name of the process which
106 * started the timer
107 * @start_pid: timer statistics field to store the pid of the task which
108 * started the timer
109 *
110 * The hrtimer structure must be initialized by hrtimer_init()
111 */
112struct hrtimer {
113 struct rb_node node;
114 ktime_t expires;
115 enum hrtimer_restart (*function)(struct hrtimer *);
116 struct hrtimer_clock_base *base;
117 unsigned long state;
118#ifdef CONFIG_HIGH_RES_TIMERS
119 enum hrtimer_cb_mode cb_mode;
120 struct list_head cb_entry;
121#endif
122#ifdef CONFIG_TIMER_STATS
123 void *start_site;
124 char start_comm[16];
125 int start_pid;
126#endif
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 */
136struct hrtimer_sleeper {
137 struct hrtimer timer;
138 struct task_struct *task;
139};
140
141/**
142 * struct hrtimer_clock_base - the timer base for a specific clock
143 * @cpu_base: per cpu clock base
144 * @index: clock type index for per_cpu support when moving a
145 * timer to a base on another cpu.
146 * @active: red black tree root node for the active timers
147 * @first: pointer to the timer node which expires first
148 * @resolution: the resolution of the clock, in nanoseconds
149 * @get_time: function to retrieve the current time of the clock
150 * @get_softirq_time: function to retrieve the current time from the softirq
151 * @softirq_time: the time when running the hrtimer queue in the softirq
152 * @cb_pending: list of timers where the callback is pending
153 * @offset: offset of this clock to the monotonic base
154 * @reprogram: function to reprogram the timer event
155 */
156struct hrtimer_clock_base {
157 struct hrtimer_cpu_base *cpu_base;
158 clockid_t index;
159 struct rb_root active;
160 struct rb_node *first;
161 ktime_t resolution;
162 ktime_t (*get_time)(void);
163 ktime_t (*get_softirq_time)(void);
164 ktime_t softirq_time;
165#ifdef CONFIG_HIGH_RES_TIMERS
166 ktime_t offset;
167 int (*reprogram)(struct hrtimer *t,
168 struct hrtimer_clock_base *b,
169 ktime_t n);
170#endif
171};
172
173#define HRTIMER_MAX_CLOCK_BASES 2
174
175/*
176 * struct hrtimer_cpu_base - the per cpu clock bases
177 * @lock: lock protecting the base and associated clock bases
178 * and timers
179 * @lock_key: the lock_class_key for use with lockdep
180 * @clock_base: array of clock bases for this cpu
181 * @curr_timer: the timer which is executing a callback right now
182 * @expires_next: absolute time of the next event which was scheduled
183 * via clock_set_next_event()
184 * @hres_active: State of high resolution mode
185 * @check_clocks: Indictator, when set evaluate time source and clock
186 * event devices whether high resolution mode can be
187 * activated.
188 * @cb_pending: Expired timers are moved from the rbtree to this
189 * list in the timer interrupt. The list is processed
190 * in the softirq.
191 * @nr_events: Total number of timer interrupt events
192 */
193struct hrtimer_cpu_base {
194 spinlock_t lock;
195 struct lock_class_key lock_key;
196 struct hrtimer_clock_base clock_base[HRTIMER_MAX_CLOCK_BASES];
197#ifdef CONFIG_HIGH_RES_TIMERS
198 ktime_t expires_next;
199 int hres_active;
200 struct list_head cb_pending;
201 unsigned long nr_events;
202#endif
203};
204
205#ifdef CONFIG_HIGH_RES_TIMERS
206struct clock_event_device;
207
208extern void clock_was_set(void);
209extern void hres_timers_resume(void);
210extern void hrtimer_interrupt(struct clock_event_device *dev);
211
212/*
213 * In high resolution mode the time reference must be read accurate
214 */
215static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
216{
217 return timer->base->get_time();
218}
219
220/*
221 * The resolution of the clocks. The resolution value is returned in
222 * the clock_getres() system call to give application programmers an
223 * idea of the (in)accuracy of timers. Timer values are rounded up to
224 * this resolution values.
225 */
226# define KTIME_HIGH_RES (ktime_t) { .tv64 = 1 }
227# define KTIME_MONOTONIC_RES KTIME_HIGH_RES
228
229#else
230
231# define KTIME_MONOTONIC_RES KTIME_LOW_RES
232
233/*
234 * clock_was_set() is a NOP for non- high-resolution systems. The
235 * time-sorted order guarantees that a timer does not expire early and
236 * is expired in the next softirq when the clock was advanced.
237 */
238static inline void clock_was_set(void) { }
239
240static inline void hres_timers_resume(void) { }
241
242/*
243 * In non high resolution mode the time reference is taken from
244 * the base softirq time variable.
245 */
246static inline ktime_t hrtimer_cb_get_time(struct hrtimer *timer)
247{
248 return timer->base->softirq_time;
249}
250
251#endif
252
253extern ktime_t ktime_get(void);
254extern ktime_t ktime_get_real(void);
255
256/* Exported timer functions: */
257
258/* Initialize timers: */
259extern void hrtimer_init(struct hrtimer *timer, clockid_t which_clock,
260 enum hrtimer_mode mode);
261
262/* Basic timer operations: */
263extern int hrtimer_start(struct hrtimer *timer, ktime_t tim,
264 const enum hrtimer_mode mode);
265extern int hrtimer_cancel(struct hrtimer *timer);
266extern int hrtimer_try_to_cancel(struct hrtimer *timer);
267
268static inline int hrtimer_restart(struct hrtimer *timer)
269{
270 return hrtimer_start(timer, timer->expires, HRTIMER_MODE_ABS);
271}
272
273/* Query timers: */
274extern ktime_t hrtimer_get_remaining(const struct hrtimer *timer);
275extern int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp);
276
277extern ktime_t hrtimer_get_next_event(void);
278
279/*
280 * A timer is active, when it is enqueued into the rbtree or the callback
281 * function is running.
282 */
283static inline int hrtimer_active(const struct hrtimer *timer)
284{
285 return timer->state != HRTIMER_STATE_INACTIVE;
286}
287
288/*
289 * Helper function to check, whether the timer is on one of the queues
290 */
291static inline int hrtimer_is_queued(struct hrtimer *timer)
292{
293 return timer->state &
294 (HRTIMER_STATE_ENQUEUED | HRTIMER_STATE_PENDING);
295}
296
297/* Forward a hrtimer so it expires after now: */
298extern unsigned long
299hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval);
300
301/* Precise sleep: */
302extern long hrtimer_nanosleep(struct timespec *rqtp,
303 struct timespec __user *rmtp,
304 const enum hrtimer_mode mode,
305 const clockid_t clockid);
306extern long hrtimer_nanosleep_restart(struct restart_block *restart_block);
307
308extern void hrtimer_init_sleeper(struct hrtimer_sleeper *sl,
309 struct task_struct *tsk);
310
311/* Soft interrupt function to run the hrtimer queues: */
312extern void hrtimer_run_queues(void);
313
314/* Bootup initialization: */
315extern void __init hrtimers_init(void);
316
317#if BITS_PER_LONG < 64
318extern unsigned long ktime_divns(const ktime_t kt, s64 div);
319#else /* BITS_PER_LONG < 64 */
320# define ktime_divns(kt, div) (unsigned long)((kt).tv64 / (div))
321#endif
322
323/* Show pending timers: */
324extern void sysrq_timer_list_show(void);
325
326/*
327 * Timer-statistics info:
328 */
329#ifdef CONFIG_TIMER_STATS
330
331extern void timer_stats_update_stats(void *timer, pid_t pid, void *startf,
332 void *timerf, char * comm);
333
334static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
335{
336 timer_stats_update_stats(timer, timer->start_pid, timer->start_site,
337 timer->function, timer->start_comm);
338}
339
340extern void __timer_stats_hrtimer_set_start_info(struct hrtimer *timer,
341 void *addr);
342
343static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
344{
345 __timer_stats_hrtimer_set_start_info(timer, __builtin_return_address(0));
346}
347
348static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
349{
350 timer->start_site = NULL;
351}
352#else
353static inline void timer_stats_account_hrtimer(struct hrtimer *timer)
354{
355}
356
357static inline void timer_stats_hrtimer_set_start_info(struct hrtimer *timer)
358{
359}
360
361static inline void timer_stats_hrtimer_clear_start_info(struct hrtimer *timer)
362{
363}
364#endif
365
366#endif