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 * $FreeBSD$
40 */
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/callout.h>
45 #include <sys/kernel.h>
46
47 /*
48 * TODO:
49 * allocate more timeout table slots when table overflows.
50 */
51
52 /* Exported to machdep.c and/or kern_clock.c. */
53 struct callout *callout;
54 struct callout_list callfree;
55 int callwheelsize, callwheelbits, callwheelmask;
56 struct callout_tailq *callwheel;
57 int softticks; /* Like ticks, but for softclock(). */
58
59 static struct callout *nextsoftcheck; /* Next callout to be checked. */
60
61 /*
62 * The callout mechanism is based on the work of Adam M. Costello and
63 * George Varghese, published in a technical report entitled "Redesigning
64 * the BSD Callout and Timer Facilities" and modified slightly for inclusion
65 * in FreeBSD by Justin T. Gibbs. The original work on the data structures
66 * used in this implementation was published by G.Varghese and A. Lauck in
67 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
68 * the Efficient Implementation of a Timer Facility" in the Proceedings of
69 * the 11th ACM Annual Symposium on Operating Systems Principles,
70 * Austin, Texas Nov 1987.
71 */
72
73 /*
74 * Software (low priority) clock interrupt.
75 * Run periodic events from timeout queue.
76 */
77 void
78 softclock()
79 {
80 register struct callout *c;
81 register struct callout_tailq *bucket;
82 register int s;
83 register int curticks;
84 register int steps; /* #steps since we last allowed interrupts */
85
86 #ifndef MAX_SOFTCLOCK_STEPS
87 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */
88 #endif /* MAX_SOFTCLOCK_STEPS */
89
90 steps = 0;
91 s = splhigh();
92 while (softticks != ticks) {
93 softticks++;
94 /*
95 * softticks may be modified by hard clock, so cache
96 * it while we work on a given bucket.
97 */
98 curticks = softticks;
99 bucket = &callwheel[curticks & callwheelmask];
100 c = TAILQ_FIRST(bucket);
101 while (c) {
102 if (c->c_time != curticks) {
103 c = TAILQ_NEXT(c, c_links.tqe);
104 ++steps;
105 if (steps >= MAX_SOFTCLOCK_STEPS) {
106 nextsoftcheck = c;
107 /* Give interrupts a chance. */
108 splx(s);
109 s = splhigh();
110 c = nextsoftcheck;
111 steps = 0;
112 }
113 } else {
114 void (*c_func)(void *);
115 void *c_arg;
116
117 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
118 TAILQ_REMOVE(bucket, c, c_links.tqe);
119 c_func = c->c_func;
120 c_arg = c->c_arg;
121 c->c_func = NULL;
122 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
123 c->c_flags = CALLOUT_LOCAL_ALLOC;
124 SLIST_INSERT_HEAD(&callfree, c,
125 c_links.sle);
126 } else {
127 c->c_flags =
128 (c->c_flags & ~CALLOUT_PENDING);
129 }
130 splx(s);
131 c_func(c_arg);
132 s = splhigh();
133 steps = 0;
134 c = nextsoftcheck;
135 }
136 }
137 }
138 nextsoftcheck = NULL;
139 splx(s);
140 }
141
142 /*
143 * timeout --
144 * Execute a function after a specified length of time.
145 *
146 * untimeout --
147 * Cancel previous timeout function call.
148 *
149 * callout_handle_init --
150 * Initialize a handle so that using it with untimeout is benign.
151 *
152 * See AT&T BCI Driver Reference Manual for specification. This
153 * implementation differs from that one in that although an
154 * identification value is returned from timeout, the original
155 * arguments to timeout as well as the identifier are used to
156 * identify entries for untimeout.
157 */
158 struct callout_handle
159 timeout(ftn, arg, to_ticks)
160 timeout_t *ftn;
161 void *arg;
162 register int to_ticks;
163 {
164 int s;
165 struct callout *new;
166 struct callout_handle handle;
167
168 s = splhigh();
169
170 /* Fill in the next free callout structure. */
171 new = SLIST_FIRST(&callfree);
172 if (new == NULL)
173 /* XXX Attempt to malloc first */
174 panic("timeout table full");
175 SLIST_REMOVE_HEAD(&callfree, c_links.sle);
176
177 callout_reset(new, to_ticks, ftn, arg);
178
179 handle.callout = new;
180 splx(s);
181 return (handle);
182 }
183
184 void
185 untimeout(ftn, arg, handle)
186 timeout_t *ftn;
187 void *arg;
188 struct callout_handle handle;
189 {
190 register int s;
191
192 /*
193 * Check for a handle that was initialized
194 * by callout_handle_init, but never used
195 * for a real timeout.
196 */
197 if (handle.callout == NULL)
198 return;
199
200 s = splhigh();
201 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
202 callout_stop(handle.callout);
203 splx(s);
204 }
205
206 void
207 callout_handle_init(struct callout_handle *handle)
208 {
209 handle->callout = NULL;
210 }
211
212 /*
213 * New interface; clients allocate their own callout structures.
214 *
215 * callout_reset() - establish or change a timeout
216 * callout_stop() - disestablish a timeout
217 * callout_init() - initialize a callout structure so that it can
218 * safely be passed to callout_reset() and callout_stop()
219 *
220 * <sys/callout.h> defines three convenience macros:
221 *
222 * callout_active() - returns truth if callout has not been serviced
223 * callout_pending() - returns truth if callout is still waiting for timeout
224 * callout_deactivate() - marks the callout as having been serviced
225 */
226 void
227 callout_reset(c, to_ticks, ftn, arg)
228 struct callout *c;
229 int to_ticks;
230 void (*ftn) __P((void *));
231 void *arg;
232 {
233 int s;
234
235 s = splhigh();
236 if (c->c_flags & CALLOUT_PENDING)
237 callout_stop(c);
238
239 /*
240 * We could spl down here and back up at the TAILQ_INSERT_TAIL,
241 * but there's no point since doing this setup doesn't take much
242 * time.
243 */
244 if (to_ticks <= 0)
245 to_ticks = 1;
246
247 c->c_arg = arg;
248 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
249 c->c_func = ftn;
250 c->c_time = ticks + to_ticks;
251 TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask],
252 c, c_links.tqe);
253 splx(s);
254
255 }
256
257 int
258 callout_stop(c)
259 struct callout *c;
260 {
261 int s;
262
263 s = splhigh();
264 /*
265 * Don't attempt to delete a callout that's not on the queue.
266 */
267 if (!(c->c_flags & CALLOUT_PENDING)) {
268 c->c_flags &= ~CALLOUT_ACTIVE;
269 splx(s);
270 return (0);
271 }
272 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
273
274 if (nextsoftcheck == c) {
275 nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
276 }
277 TAILQ_REMOVE(&callwheel[c->c_time & callwheelmask], c, c_links.tqe);
278 c->c_func = NULL;
279
280 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
281 SLIST_INSERT_HEAD(&callfree, c, c_links.sle);
282 }
283 splx(s);
284 return (1);
285 }
286
287 void
288 callout_init(c)
289 struct callout *c;
290 {
291 bzero(c, sizeof *c);
292 }
293
294 #ifdef APM_FIXUP_CALLTODO
295 /*
296 * Adjust the kernel calltodo timeout list. This routine is used after
297 * an APM resume to recalculate the calltodo timer list values with the
298 * number of hz's we have been sleeping. The next hardclock() will detect
299 * that there are fired timers and run softclock() to execute them.
300 *
301 * Please note, I have not done an exhaustive analysis of what code this
302 * might break. I am motivated to have my select()'s and alarm()'s that
303 * have expired during suspend firing upon resume so that the applications
304 * which set the timer can do the maintanence the timer was for as close
305 * as possible to the originally intended time. Testing this code for a
306 * week showed that resuming from a suspend resulted in 22 to 25 timers
307 * firing, which seemed independant on whether the suspend was 2 hours or
308 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu>
309 */
310 void
311 adjust_timeout_calltodo(time_change)
312 struct timeval *time_change;
313 {
314 register struct callout *p;
315 unsigned long delta_ticks;
316 int s;
317
318 /*
319 * How many ticks were we asleep?
320 * (stolen from tvtohz()).
321 */
322
323 /* Don't do anything */
324 if (time_change->tv_sec < 0)
325 return;
326 else if (time_change->tv_sec <= LONG_MAX / 1000000)
327 delta_ticks = (time_change->tv_sec * 1000000 +
328 time_change->tv_usec + (tick - 1)) / tick + 1;
329 else if (time_change->tv_sec <= LONG_MAX / hz)
330 delta_ticks = time_change->tv_sec * hz +
331 (time_change->tv_usec + (tick - 1)) / tick + 1;
332 else
333 delta_ticks = LONG_MAX;
334
335 if (delta_ticks > INT_MAX)
336 delta_ticks = INT_MAX;
337
338 /*
339 * Now rip through the timer calltodo list looking for timers
340 * to expire.
341 */
342
343 /* don't collide with softclock() */
344 s = splhigh();
345 for (p = calltodo.c_next; p != NULL; p = p->c_next) {
346 p->c_time -= delta_ticks;
347
348 /* Break if the timer had more time on it than delta_ticks */
349 if (p->c_time > 0)
350 break;
351
352 /* take back the ticks the timer didn't use (p->c_time <= 0) */
353 delta_ticks = -p->c_time;
354 }
355 splx(s);
356
357 return;
358 }
359 #endif /* APM_FIXUP_CALLTODO */
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