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: releng/5.0/sys/kern/kern_timeout.c 102961 2002-09-05 11:42:03Z phk $
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. */
55 struct callout *callout;
56 struct callout_list callfree;
57 int callwheelsize, callwheelbits, callwheelmask;
58 struct callout_tailq *callwheel;
59 int softticks; /* Like ticks, but for softclock(). */
60 struct mtx callout_lock;
61
62 static struct callout *nextsoftcheck; /* Next callout to be checked. */
63
64 /*
65 * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization
66 *
67 * This code is called very early in the kernel initialization sequence,
68 * and may be called more then once.
69 */
70 caddr_t
71 kern_timeout_callwheel_alloc(caddr_t v)
72 {
73 /*
74 * Calculate callout wheel size
75 */
76 for (callwheelsize = 1, callwheelbits = 0;
77 callwheelsize < ncallout;
78 callwheelsize <<= 1, ++callwheelbits)
79 ;
80 callwheelmask = callwheelsize - 1;
81
82 callout = (struct callout *)v;
83 v = (caddr_t)(callout + ncallout);
84 callwheel = (struct callout_tailq *)v;
85 v = (caddr_t)(callwheel + callwheelsize);
86 return(v);
87 }
88
89 /*
90 * kern_timeout_callwheel_init() - initialize previously reserved callwheel
91 * space.
92 *
93 * This code is called just once, after the space reserved for the
94 * callout wheel has been finalized.
95 */
96 void
97 kern_timeout_callwheel_init(void)
98 {
99 int i;
100
101 SLIST_INIT(&callfree);
102 for (i = 0; i < ncallout; i++) {
103 callout_init(&callout[i], 0);
104 callout[i].c_flags = CALLOUT_LOCAL_ALLOC;
105 SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle);
106 }
107 for (i = 0; i < callwheelsize; i++) {
108 TAILQ_INIT(&callwheel[i]);
109 }
110 mtx_init(&callout_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE);
111 }
112
113 /*
114 * The callout mechanism is based on the work of Adam M. Costello and
115 * George Varghese, published in a technical report entitled "Redesigning
116 * the BSD Callout and Timer Facilities" and modified slightly for inclusion
117 * in FreeBSD by Justin T. Gibbs. The original work on the data structures
118 * used in this implementation was published by G.Varghese and A. Lauck in
119 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
120 * the Efficient Implementation of a Timer Facility" in the Proceedings of
121 * the 11th ACM Annual Symposium on Operating Systems Principles,
122 * Austin, Texas Nov 1987.
123 */
124
125 /*
126 * Software (low priority) clock interrupt.
127 * Run periodic events from timeout queue.
128 */
129 void
130 softclock(void *dummy)
131 {
132 struct callout *c;
133 struct callout_tailq *bucket;
134 int curticks;
135 int steps; /* #steps since we last allowed interrupts */
136 #ifdef DIAGNOSTIC
137 struct bintime bt1, bt2;
138 struct timespec ts2;
139 static uint64_t maxdt = 18446744073709551LL; /* 1 msec */
140 #endif
141
142 #ifndef MAX_SOFTCLOCK_STEPS
143 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */
144 #endif /* MAX_SOFTCLOCK_STEPS */
145
146 steps = 0;
147 mtx_lock_spin(&callout_lock);
148 while (softticks != ticks) {
149 softticks++;
150 /*
151 * softticks may be modified by hard clock, so cache
152 * it while we work on a given bucket.
153 */
154 curticks = softticks;
155 bucket = &callwheel[curticks & callwheelmask];
156 c = TAILQ_FIRST(bucket);
157 while (c) {
158 if (c->c_time != curticks) {
159 c = TAILQ_NEXT(c, c_links.tqe);
160 ++steps;
161 if (steps >= MAX_SOFTCLOCK_STEPS) {
162 nextsoftcheck = c;
163 /* Give interrupts a chance. */
164 mtx_unlock_spin(&callout_lock);
165 ; /* nothing */
166 mtx_lock_spin(&callout_lock);
167 c = nextsoftcheck;
168 steps = 0;
169 }
170 } else {
171 void (*c_func)(void *);
172 void *c_arg;
173 int c_flags;
174
175 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
176 TAILQ_REMOVE(bucket, c, c_links.tqe);
177 c_func = c->c_func;
178 c_arg = c->c_arg;
179 c_flags = c->c_flags;
180 c->c_func = NULL;
181 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
182 c->c_flags = CALLOUT_LOCAL_ALLOC;
183 SLIST_INSERT_HEAD(&callfree, c,
184 c_links.sle);
185 } else {
186 c->c_flags =
187 (c->c_flags & ~CALLOUT_PENDING);
188 }
189 mtx_unlock_spin(&callout_lock);
190 if (!(c_flags & CALLOUT_MPSAFE))
191 mtx_lock(&Giant);
192 #ifdef DIAGNOSTIC
193 binuptime(&bt1);
194 #endif
195 c_func(c_arg);
196 #ifdef DIAGNOSTIC
197 binuptime(&bt2);
198 bintime_sub(&bt2, &bt1);
199 if (bt2.frac > maxdt) {
200 bintime2timespec(&bt2, &ts2);
201 printf(
202 "Expensive timeout(9) function: %p(%p) %d.%09ld\n",
203 c_func, c_arg,
204 ts2.tv_sec, ts2.tv_nsec);
205 }
206 #endif
207 if (!(c_flags & CALLOUT_MPSAFE))
208 mtx_unlock(&Giant);
209 mtx_lock_spin(&callout_lock);
210 steps = 0;
211 c = nextsoftcheck;
212 }
213 }
214 }
215 nextsoftcheck = NULL;
216 mtx_unlock_spin(&callout_lock);
217 }
218
219 /*
220 * timeout --
221 * Execute a function after a specified length of time.
222 *
223 * untimeout --
224 * Cancel previous timeout function call.
225 *
226 * callout_handle_init --
227 * Initialize a handle so that using it with untimeout is benign.
228 *
229 * See AT&T BCI Driver Reference Manual for specification. This
230 * implementation differs from that one in that although an
231 * identification value is returned from timeout, the original
232 * arguments to timeout as well as the identifier are used to
233 * identify entries for untimeout.
234 */
235 struct callout_handle
236 timeout(ftn, arg, to_ticks)
237 timeout_t *ftn;
238 void *arg;
239 int to_ticks;
240 {
241 struct callout *new;
242 struct callout_handle handle;
243
244 mtx_lock_spin(&callout_lock);
245
246 /* Fill in the next free callout structure. */
247 new = SLIST_FIRST(&callfree);
248 if (new == NULL)
249 /* XXX Attempt to malloc first */
250 panic("timeout table full");
251 SLIST_REMOVE_HEAD(&callfree, c_links.sle);
252
253 callout_reset(new, to_ticks, ftn, arg);
254
255 handle.callout = new;
256 mtx_unlock_spin(&callout_lock);
257 return (handle);
258 }
259
260 void
261 untimeout(ftn, arg, handle)
262 timeout_t *ftn;
263 void *arg;
264 struct callout_handle handle;
265 {
266
267 /*
268 * Check for a handle that was initialized
269 * by callout_handle_init, but never used
270 * for a real timeout.
271 */
272 if (handle.callout == NULL)
273 return;
274
275 mtx_lock_spin(&callout_lock);
276 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
277 callout_stop(handle.callout);
278 mtx_unlock_spin(&callout_lock);
279 }
280
281 void
282 callout_handle_init(struct callout_handle *handle)
283 {
284 handle->callout = NULL;
285 }
286
287 /*
288 * New interface; clients allocate their own callout structures.
289 *
290 * callout_reset() - establish or change a timeout
291 * callout_stop() - disestablish a timeout
292 * callout_init() - initialize a callout structure so that it can
293 * safely be passed to callout_reset() and callout_stop()
294 *
295 * <sys/callout.h> defines three convenience macros:
296 *
297 * callout_active() - returns truth if callout has not been serviced
298 * callout_pending() - returns truth if callout is still waiting for timeout
299 * callout_deactivate() - marks the callout as having been serviced
300 */
301 void
302 callout_reset(c, to_ticks, ftn, arg)
303 struct callout *c;
304 int to_ticks;
305 void (*ftn)(void *);
306 void *arg;
307 {
308
309 mtx_lock_spin(&callout_lock);
310 if (c->c_flags & CALLOUT_PENDING)
311 callout_stop(c);
312
313 /*
314 * We could unlock callout_lock here and lock it again before the
315 * TAILQ_INSERT_TAIL, but there's no point since doing this setup
316 * doesn't take much time.
317 */
318 if (to_ticks <= 0)
319 to_ticks = 1;
320
321 c->c_arg = arg;
322 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
323 c->c_func = ftn;
324 c->c_time = ticks + to_ticks;
325 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask],
326 c, c_links.tqe);
327 mtx_unlock_spin(&callout_lock);
328 }
329
330 int
331 callout_stop(c)
332 struct callout *c;
333 {
334
335 mtx_lock_spin(&callout_lock);
336 /*
337 * Don't attempt to delete a callout that's not on the queue.
338 */
339 if (!(c->c_flags & CALLOUT_PENDING)) {
340 c->c_flags &= ~CALLOUT_ACTIVE;
341 mtx_unlock_spin(&callout_lock);
342 return (0);
343 }
344 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
345
346 if (nextsoftcheck == c) {
347 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
348 }
349 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe);
350 c->c_func = NULL;
351
352 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
353 SLIST_INSERT_HEAD(&callfree, c, c_links.sle);
354 }
355 mtx_unlock_spin(&callout_lock);
356 return (1);
357 }
358
359 void
360 callout_init(c, mpsafe)
361 struct callout *c;
362 int mpsafe;
363 {
364 bzero(c, sizeof *c);
365 if (mpsafe)
366 c->c_flags |= CALLOUT_MPSAFE;
367 }
368
369 #ifdef APM_FIXUP_CALLTODO
370 /*
371 * Adjust the kernel calltodo timeout list. This routine is used after
372 * an APM resume to recalculate the calltodo timer list values with the
373 * number of hz's we have been sleeping. The next hardclock() will detect
374 * that there are fired timers and run softclock() to execute them.
375 *
376 * Please note, I have not done an exhaustive analysis of what code this
377 * might break. I am motivated to have my select()'s and alarm()'s that
378 * have expired during suspend firing upon resume so that the applications
379 * which set the timer can do the maintanence the timer was for as close
380 * as possible to the originally intended time. Testing this code for a
381 * week showed that resuming from a suspend resulted in 22 to 25 timers
382 * firing, which seemed independant on whether the suspend was 2 hours or
383 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu>
384 */
385 void
386 adjust_timeout_calltodo(time_change)
387 struct timeval *time_change;
388 {
389 register struct callout *p;
390 unsigned long delta_ticks;
391
392 /*
393 * How many ticks were we asleep?
394 * (stolen from tvtohz()).
395 */
396
397 /* Don't do anything */
398 if (time_change->tv_sec < 0)
399 return;
400 else if (time_change->tv_sec <= LONG_MAX / 1000000)
401 delta_ticks = (time_change->tv_sec * 1000000 +
402 time_change->tv_usec + (tick - 1)) / tick + 1;
403 else if (time_change->tv_sec <= LONG_MAX / hz)
404 delta_ticks = time_change->tv_sec * hz +
405 (time_change->tv_usec + (tick - 1)) / tick + 1;
406 else
407 delta_ticks = LONG_MAX;
408
409 if (delta_ticks > INT_MAX)
410 delta_ticks = INT_MAX;
411
412 /*
413 * Now rip through the timer calltodo list looking for timers
414 * to expire.
415 */
416
417 /* don't collide with softclock() */
418 mtx_lock_spin(&callout_lock);
419 for (p = calltodo.c_next; p != NULL; p = p->c_next) {
420 p->c_time -= delta_ticks;
421
422 /* Break if the timer had more time on it than delta_ticks */
423 if (p->c_time > 0)
424 break;
425
426 /* take back the ticks the timer didn't use (p->c_time <= 0) */
427 delta_ticks = -p->c_time;
428 }
429 mtx_unlock_spin(&callout_lock);
430
431 return;
432 }
433 #endif /* APM_FIXUP_CALLTODO */
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