1/*-
2 * Copyright (c) 1982, 1986, 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. All advertising materials mentioning features or use of this software
19 * must display the following acknowledgement:
20 * This product includes software developed by the University of
21 * California, Berkeley and its contributors.
22 * 4. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 *
38 * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
39 * $FreeBSD: head/sys/kern/kern_timeout.c 74914 2001-03-28 09:17:56Z jhb $
40 */
41
42#include <sys/param.h>
43#include <sys/systm.h>
44#include <sys/callout.h>
45#include <sys/kernel.h>
46#include <sys/lock.h>
47#include <sys/mutex.h>
48
49/*
50 * TODO:
51 * allocate more timeout table slots when table overflows.
52 */
53
54/* Exported to machdep.c and/or kern_clock.c. */
55struct callout *callout;
56struct callout_list callfree;
57int callwheelsize, callwheelbits, callwheelmask;
58struct callout_tailq *callwheel;
59int softticks; /* Like ticks, but for softclock(). */
60struct mtx callout_lock;
61
62static struct callout *nextsoftcheck; /* Next callout to be checked. */
63
64/*
65 * The callout mechanism is based on the work of Adam M. Costello and
66 * George Varghese, published in a technical report entitled "Redesigning
67 * the BSD Callout and Timer Facilities" and modified slightly for inclusion
68 * in FreeBSD by Justin T. Gibbs. The original work on the data structures
69 * used in this implementation was published by G.Varghese and A. Lauck in
70 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
71 * the Efficient Implementation of a Timer Facility" in the Proceedings of
72 * the 11th ACM Annual Symposium on Operating Systems Principles,
73 * Austin, Texas Nov 1987.
74 */
75
76/*
77 * Software (low priority) clock interrupt.
78 * Run periodic events from timeout queue.
79 */
80void
81softclock(void *dummy)
82{
83 register struct callout *c;
84 register struct callout_tailq *bucket;
85 register int s;
86 register int curticks;
87 register int steps; /* #steps since we last allowed interrupts */
88
89#ifndef MAX_SOFTCLOCK_STEPS
90#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */
91#endif /* MAX_SOFTCLOCK_STEPS */
92
93 steps = 0;
94 s = splhigh();
95 mtx_lock_spin(&callout_lock);
96 while (softticks != ticks) {
97 softticks++;
98 /*
99 * softticks may be modified by hard clock, so cache
100 * it while we work on a given bucket.
101 */
102 curticks = softticks;
103 bucket = &callwheel[curticks & callwheelmask];
104 c = TAILQ_FIRST(bucket);
105 while (c) {
106 if (c->c_time != curticks) {
107 c = TAILQ_NEXT(c, c_links.tqe);
108 ++steps;
109 if (steps >= MAX_SOFTCLOCK_STEPS) {
110 nextsoftcheck = c;
111 /* Give interrupts a chance. */
112 mtx_unlock_spin(&callout_lock);
113 splx(s);
114 s = splhigh();
115 mtx_lock_spin(&callout_lock);
116 c = nextsoftcheck;
117 steps = 0;
118 }
119 } else {
120 void (*c_func)(void *);
121 void *c_arg;
122 int c_flags;
123
124 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
125 TAILQ_REMOVE(bucket, c, c_links.tqe);
126 c_func = c->c_func;
127 c_arg = c->c_arg;
128 c_flags = c->c_flags;
129 c->c_func = NULL;
130 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
131 c->c_flags = CALLOUT_LOCAL_ALLOC;
132 SLIST_INSERT_HEAD(&callfree, c,
133 c_links.sle);
134 } else {
135 c->c_flags =
136 (c->c_flags & ~CALLOUT_PENDING);
137 }
138 mtx_unlock_spin(&callout_lock);
139 if (!(c_flags & CALLOUT_MPSAFE))
140 mtx_lock(&Giant);
141 splx(s);
142 c_func(c_arg);
143 s = splhigh();
144 if (!(c_flags & CALLOUT_MPSAFE))
145 mtx_unlock(&Giant);
146 mtx_lock_spin(&callout_lock);
147 steps = 0;
148 c = nextsoftcheck;
149 }
150 }
151 }
152 nextsoftcheck = NULL;
153 mtx_unlock_spin(&callout_lock);
154 splx(s);
155}
156
157/*
158 * timeout --
159 * Execute a function after a specified length of time.
160 *
161 * untimeout --
162 * Cancel previous timeout function call.
163 *
164 * callout_handle_init --
165 * Initialize a handle so that using it with untimeout is benign.
166 *
167 * See AT&T BCI Driver Reference Manual for specification. This
168 * implementation differs from that one in that although an
169 * identification value is returned from timeout, the original
170 * arguments to timeout as well as the identifier are used to
171 * identify entries for untimeout.
172 */
173struct callout_handle
174timeout(ftn, arg, to_ticks)
175 timeout_t *ftn;
176 void *arg;
177 int to_ticks;
178{
179 int s;
180 struct callout *new;
181 struct callout_handle handle;
182
183 s = splhigh();
184 mtx_lock_spin(&callout_lock);
185
186 /* Fill in the next free callout structure. */
187 new = SLIST_FIRST(&callfree);
188 if (new == NULL)
189 /* XXX Attempt to malloc first */
190 panic("timeout table full");
191 SLIST_REMOVE_HEAD(&callfree, c_links.sle);
192
193 callout_reset(new, to_ticks, ftn, arg);
194
195 handle.callout = new;
196 mtx_unlock_spin(&callout_lock);
197 splx(s);
198 return (handle);
199}
200
201void
202untimeout(ftn, arg, handle)
203 timeout_t *ftn;
204 void *arg;
205 struct callout_handle handle;
206{
207 register int s;
208
209 /*
210 * Check for a handle that was initialized
211 * by callout_handle_init, but never used
212 * for a real timeout.
213 */
214 if (handle.callout == NULL)
215 return;
216
217 s = splhigh();
218 mtx_lock_spin(&callout_lock);
219 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
220 callout_stop(handle.callout);
221 mtx_unlock_spin(&callout_lock);
222 splx(s);
223}
224
225void
226callout_handle_init(struct callout_handle *handle)
227{
228 handle->callout = NULL;
229}
230
231/*
232 * New interface; clients allocate their own callout structures.
233 *
234 * callout_reset() - establish or change a timeout
235 * callout_stop() - disestablish a timeout
236 * callout_init() - initialize a callout structure so that it can
237 * safely be passed to callout_reset() and callout_stop()
238 *
239 * <sys/callout.h> defines three convenience macros:
240 *
241 * callout_active() - returns truth if callout has not been serviced
242 * callout_pending() - returns truth if callout is still waiting for timeout
243 * callout_deactivate() - marks the callout as having been serviced
244 */
245void
246callout_reset(c, to_ticks, ftn, arg)
247 struct callout *c;
248 int to_ticks;
249 void (*ftn) __P((void *));
250 void *arg;
251{
252 int s;
253
254 s = splhigh();
255 mtx_lock_spin(&callout_lock);
256 if (c->c_flags & CALLOUT_PENDING)
257 callout_stop(c);
258
259 /*
260 * We could spl down here and back up at the TAILQ_INSERT_TAIL,
261 * but there's no point since doing this setup doesn't take much
262 * time.
263 */
264 if (to_ticks <= 0)
265 to_ticks = 1;
266
267 c->c_arg = arg;
268 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
269 c->c_func = ftn;
270 c->c_time = ticks + to_ticks;
271 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask],
272 c, c_links.tqe);
273 mtx_unlock_spin(&callout_lock);
274 splx(s);
275}
276
277void
278callout_stop(c)
279 struct callout *c;
280{
281 int s;
282
283 s = splhigh();
284 mtx_lock_spin(&callout_lock);
285 /*
286 * Don't attempt to delete a callout that's not on the queue.
287 */
288 if (!(c->c_flags & CALLOUT_PENDING)) {
289 c->c_flags &= ~CALLOUT_ACTIVE;
290 mtx_unlock_spin(&callout_lock);
291 splx(s);
292 return;
293 }
294 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
295
296 if (nextsoftcheck == c) {
297 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
298 }
299 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe);
300 c->c_func = NULL;
301
302 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
303 SLIST_INSERT_HEAD(&callfree, c, c_links.sle);
304 }
305 mtx_unlock_spin(&callout_lock);
306 splx(s);
307}
308
309void
310callout_init(c, mpsafe)
311 struct callout *c;
312 int mpsafe;
313{
314 bzero(c, sizeof *c);
315 if (mpsafe)
316 c->c_flags |= CALLOUT_MPSAFE;
317}
318
319#ifdef APM_FIXUP_CALLTODO
320/*
321 * Adjust the kernel calltodo timeout list. This routine is used after
322 * an APM resume to recalculate the calltodo timer list values with the
323 * number of hz's we have been sleeping. The next hardclock() will detect
324 * that there are fired timers and run softclock() to execute them.
325 *
326 * Please note, I have not done an exhaustive analysis of what code this
327 * might break. I am motivated to have my select()'s and alarm()'s that
328 * have expired during suspend firing upon resume so that the applications
329 * which set the timer can do the maintanence the timer was for as close
330 * as possible to the originally intended time. Testing this code for a
331 * week showed that resuming from a suspend resulted in 22 to 25 timers
332 * firing, which seemed independant on whether the suspend was 2 hours or
333 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu>
334 */
335void
336adjust_timeout_calltodo(time_change)
337 struct timeval *time_change;
338{
339 register struct callout *p;
340 unsigned long delta_ticks;
341 int s;
342
343 /*
344 * How many ticks were we asleep?
345 * (stolen from tvtohz()).
346 */
347
348 /* Don't do anything */
349 if (time_change->tv_sec < 0)
350 return;
351 else if (time_change->tv_sec <= LONG_MAX / 1000000)
352 delta_ticks = (time_change->tv_sec * 1000000 +
353 time_change->tv_usec + (tick - 1)) / tick + 1;
354 else if (time_change->tv_sec <= LONG_MAX / hz)
355 delta_ticks = time_change->tv_sec * hz +
356 (time_change->tv_usec + (tick - 1)) / tick + 1;
357 else
358 delta_ticks = LONG_MAX;
359
360 if (delta_ticks > INT_MAX)
361 delta_ticks = INT_MAX;
362
363 /*
364 * Now rip through the timer calltodo list looking for timers
365 * to expire.
366 */
367
368 /* don't collide with softclock() */
369 s = splhigh();
370 mtx_lock_spin(&callout_lock);
371 for (p = calltodo.c_next; p != NULL; p = p->c_next) {
372 p->c_time -= delta_ticks;
373
374 /* Break if the timer had more time on it than delta_ticks */
375 if (p->c_time > 0)
376 break;
377
378 /* take back the ticks the timer didn't use (p->c_time <= 0) */
379 delta_ticks = -p->c_time;
380 }
381 mtx_unlock_spin(&callout_lock);
382 splx(s);
383
384 return;
385}
386#endif /* APM_FIXUP_CALLTODO */