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/5.1/sys/kern/kern_timeout.c 110185 2003-02-01 10:06:40Z 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 maxdt = bt2.frac;
201 bintime2timespec(&bt2, &ts2);
202 printf(
203 "Expensive timeout(9) function: %p(%p) %d.%09ld s\n",
204 c_func, c_arg,
205 ts2.tv_sec, ts2.tv_nsec);
206 }
207 #endif
208 if (!(c_flags & CALLOUT_MPSAFE))
209 mtx_unlock(&Giant);
210 mtx_lock_spin(&callout_lock);
211 steps = 0;
212 c = nextsoftcheck;
213 }
214 }
215 }
216 nextsoftcheck = NULL;
217 mtx_unlock_spin(&callout_lock);
218 }
219
220 /*
221 * timeout --
222 * Execute a function after a specified length of time.
223 *
224 * untimeout --
225 * Cancel previous timeout function call.
226 *
227 * callout_handle_init --
228 * Initialize a handle so that using it with untimeout is benign.
229 *
230 * See AT&T BCI Driver Reference Manual for specification. This
231 * implementation differs from that one in that although an
232 * identification value is returned from timeout, the original
233 * arguments to timeout as well as the identifier are used to
234 * identify entries for untimeout.
235 */
236 struct callout_handle
237 timeout(ftn, arg, to_ticks)
238 timeout_t *ftn;
239 void *arg;
240 int to_ticks;
241 {
242 struct callout *new;
243 struct callout_handle handle;
244
245 mtx_lock_spin(&callout_lock);
246
247 /* Fill in the next free callout structure. */
248 new = SLIST_FIRST(&callfree);
249 if (new == NULL)
250 /* XXX Attempt to malloc first */
251 panic("timeout table full");
252 SLIST_REMOVE_HEAD(&callfree, c_links.sle);
253
254 callout_reset(new, to_ticks, ftn, arg);
255
256 handle.callout = new;
257 mtx_unlock_spin(&callout_lock);
258 return (handle);
259 }
260
261 void
262 untimeout(ftn, arg, handle)
263 timeout_t *ftn;
264 void *arg;
265 struct callout_handle handle;
266 {
267
268 /*
269 * Check for a handle that was initialized
270 * by callout_handle_init, but never used
271 * for a real timeout.
272 */
273 if (handle.callout == NULL)
274 return;
275
276 mtx_lock_spin(&callout_lock);
277 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
278 callout_stop(handle.callout);
279 mtx_unlock_spin(&callout_lock);
280 }
281
282 void
283 callout_handle_init(struct callout_handle *handle)
284 {
285 handle->callout = NULL;
286 }
287
288 /*
289 * New interface; clients allocate their own callout structures.
290 *
291 * callout_reset() - establish or change a timeout
292 * callout_stop() - disestablish a timeout
293 * callout_init() - initialize a callout structure so that it can
294 * safely be passed to callout_reset() and callout_stop()
295 *
296 * <sys/callout.h> defines three convenience macros:
297 *
298 * callout_active() - returns truth if callout has not been serviced
299 * callout_pending() - returns truth if callout is still waiting for timeout
300 * callout_deactivate() - marks the callout as having been serviced
301 */
302 void
303 callout_reset(c, to_ticks, ftn, arg)
304 struct callout *c;
305 int to_ticks;
306 void (*ftn)(void *);
307 void *arg;
308 {
309
310 mtx_lock_spin(&callout_lock);
311 if (c->c_flags & CALLOUT_PENDING)
312 callout_stop(c);
313
314 /*
315 * We could unlock callout_lock here and lock it again before the
316 * TAILQ_INSERT_TAIL, but there's no point since doing this setup
317 * doesn't take much time.
318 */
319 if (to_ticks <= 0)
320 to_ticks = 1;
321
322 c->c_arg = arg;
323 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
324 c->c_func = ftn;
325 c->c_time = ticks + to_ticks;
326 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask],
327 c, c_links.tqe);
328 mtx_unlock_spin(&callout_lock);
329 }
330
331 int
332 callout_stop(c)
333 struct callout *c;
334 {
335
336 mtx_lock_spin(&callout_lock);
337 /*
338 * Don't attempt to delete a callout that's not on the queue.
339 */
340 if (!(c->c_flags & CALLOUT_PENDING)) {
341 c->c_flags &= ~CALLOUT_ACTIVE;
342 mtx_unlock_spin(&callout_lock);
343 return (0);
344 }
345 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
346
347 if (nextsoftcheck == c) {
348 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
349 }
350 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe);
351 c->c_func = NULL;
352
353 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
354 SLIST_INSERT_HEAD(&callfree, c, c_links.sle);
355 }
356 mtx_unlock_spin(&callout_lock);
357 return (1);
358 }
359
360 void
361 callout_init(c, mpsafe)
362 struct callout *c;
363 int mpsafe;
364 {
365 bzero(c, sizeof *c);
366 if (mpsafe)
367 c->c_flags |= CALLOUT_MPSAFE;
368 }
369
370 #ifdef APM_FIXUP_CALLTODO
371 /*
372 * Adjust the kernel calltodo timeout list. This routine is used after
373 * an APM resume to recalculate the calltodo timer list values with the
374 * number of hz's we have been sleeping. The next hardclock() will detect
375 * that there are fired timers and run softclock() to execute them.
376 *
377 * Please note, I have not done an exhaustive analysis of what code this
378 * might break. I am motivated to have my select()'s and alarm()'s that
379 * have expired during suspend firing upon resume so that the applications
380 * which set the timer can do the maintanence the timer was for as close
381 * as possible to the originally intended time. Testing this code for a
382 * week showed that resuming from a suspend resulted in 22 to 25 timers
383 * firing, which seemed independant on whether the suspend was 2 hours or
384 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu>
385 */
386 void
387 adjust_timeout_calltodo(time_change)
388 struct timeval *time_change;
389 {
390 register struct callout *p;
391 unsigned long delta_ticks;
392
393 /*
394 * How many ticks were we asleep?
395 * (stolen from tvtohz()).
396 */
397
398 /* Don't do anything */
399 if (time_change->tv_sec < 0)
400 return;
401 else if (time_change->tv_sec <= LONG_MAX / 1000000)
402 delta_ticks = (time_change->tv_sec * 1000000 +
403 time_change->tv_usec + (tick - 1)) / tick + 1;
404 else if (time_change->tv_sec <= LONG_MAX / hz)
405 delta_ticks = time_change->tv_sec * hz +
406 (time_change->tv_usec + (tick - 1)) / tick + 1;
407 else
408 delta_ticks = LONG_MAX;
409
410 if (delta_ticks > INT_MAX)
411 delta_ticks = INT_MAX;
412
413 /*
414 * Now rip through the timer calltodo list looking for timers
415 * to expire.
416 */
417
418 /* don't collide with softclock() */
419 mtx_lock_spin(&callout_lock);
420 for (p = calltodo.c_next; p != NULL; p = p->c_next) {
421 p->c_time -= delta_ticks;
422
423 /* Break if the timer had more time on it than delta_ticks */
424 if (p->c_time > 0)
425 break;
426
427 /* take back the ticks the timer didn't use (p->c_time <= 0) */
428 delta_ticks = -p->c_time;
429 }
430 mtx_unlock_spin(&callout_lock);
431
432 return;
433 }
434 #endif /* APM_FIXUP_CALLTODO */
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