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[dragonfly.git] / sys / kern / kern_timeout.c
CommitLineData
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1/*
2 * Copyright (c) 2004 The DragonFly Project. All rights reserved.
3 *
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
16 * distribution.
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34/*
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35 * Copyright (c) 1982, 1986, 1991, 1993
36 * The Regents of the University of California. All rights reserved.
37 * (c) UNIX System Laboratories, Inc.
38 * All or some portions of this file are derived from material licensed
39 * to the University of California by American Telephone and Telegraph
40 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
41 * the permission of UNIX System Laboratories, Inc.
42 *
43 * Redistribution and use in source and binary forms, with or without
44 * modification, are permitted provided that the following conditions
45 * are met:
46 * 1. Redistributions of source code must retain the above copyright
47 * notice, this list of conditions and the following disclaimer.
48 * 2. Redistributions in binary form must reproduce the above copyright
49 * notice, this list of conditions and the following disclaimer in the
50 * documentation and/or other materials provided with the distribution.
51 * 3. All advertising materials mentioning features or use of this software
52 * must display the following acknowledgement:
53 * This product includes software developed by the University of
54 * California, Berkeley and its contributors.
55 * 4. Neither the name of the University nor the names of its contributors
56 * may be used to endorse or promote products derived from this software
57 * without specific prior written permission.
58 *
59 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
60 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
61 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
62 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
63 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
64 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
65 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
66 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
67 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
68 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
69 * SUCH DAMAGE.
70 *
71 * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
72 * $FreeBSD: src/sys/kern/kern_timeout.c,v 1.59.2.1 2001/11/13 18:24:52 archie Exp $
bb1a3ed4 73 * $DragonFly: src/sys/kern/kern_timeout.c,v 1.27 2007/11/14 18:27:52 swildner Exp $
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74 */
75/*
76 * DRAGONFLY BGL STATUS
77 *
78 * All the API functions should be MP safe.
79 *
80 * The callback functions will be flagged as being MP safe if the
81 * timeout structure is initialized with callout_init_mp() instead of
82 * callout_init().
83 *
84 * The helper threads cannot be made preempt-capable until after we
85 * clean up all the uses of splsoftclock() and related interlocks (which
86 * require the related functions to be MP safe as well).
87 */
88/*
89 * The callout mechanism is based on the work of Adam M. Costello and
90 * George Varghese, published in a technical report entitled "Redesigning
91 * the BSD Callout and Timer Facilities" and modified slightly for inclusion
92 * in FreeBSD by Justin T. Gibbs. The original work on the data structures
93 * used in this implementation was published by G. Varghese and T. Lauck in
94 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
95 * the Efficient Implementation of a Timer Facility" in the Proceedings of
96 * the 11th ACM Annual Symposium on Operating Systems Principles,
97 * Austin, Texas Nov 1987.
98 *
99 * The per-cpu augmentation was done by Matthew Dillon.
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100 */
101
102#include <sys/param.h>
103#include <sys/systm.h>
104#include <sys/callout.h>
105#include <sys/kernel.h>
ef0fdad1 106#include <sys/interrupt.h>
4b5f931b 107#include <sys/thread.h>
88c4d2f6 108#include <sys/thread2.h>
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109
110#ifndef MAX_SOFTCLOCK_STEPS
111#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */
112#endif
113
114
115struct softclock_pcpu {
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116 struct callout_tailq *callwheel;
117 struct callout * volatile next;
118 int softticks; /* softticks index */
119 int curticks; /* per-cpu ticks counter */
120 int isrunning;
121 struct thread thread;
122
123};
124
125typedef struct softclock_pcpu *softclock_pcpu_t;
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126
127/*
128 * TODO:
129 * allocate more timeout table slots when table overflows.
130 */
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131static MALLOC_DEFINE(M_CALLOUT, "callout", "callout structures");
132static int callwheelsize;
133static int callwheelbits;
134static int callwheelmask;
135static struct softclock_pcpu softclock_pcpu_ary[MAXCPU];
136
137static void softclock_handler(void *arg);
138
139static void
140swi_softclock_setup(void *arg)
141{
142 int cpu;
143 int i;
984263bc 144
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145 /*
146 * Figure out how large a callwheel we need. It must be a power of 2.
147 */
148 callwheelsize = 1;
149 callwheelbits = 0;
150 while (callwheelsize < ncallout) {
151 callwheelsize <<= 1;
152 ++callwheelbits;
153 }
154 callwheelmask = callwheelsize - 1;
984263bc 155
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156 /*
157 * Initialize per-cpu data structures.
158 */
159 for (cpu = 0; cpu < ncpus; ++cpu) {
160 softclock_pcpu_t sc;
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161
162 sc = &softclock_pcpu_ary[cpu];
163
77652cad 164 sc->callwheel = kmalloc(sizeof(*sc->callwheel) * callwheelsize,
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165 M_CALLOUT, M_WAITOK|M_ZERO);
166 for (i = 0; i < callwheelsize; ++i)
167 TAILQ_INIT(&sc->callwheel[i]);
168
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169 /*
170 * Create a preemption-capable thread for each cpu to handle
171 * softclock timeouts on that cpu. The preemption can only
172 * be blocked by a critical section. The thread can itself
173 * be preempted by normal interrupts.
174 */
175 lwkt_create(softclock_handler, sc, NULL,
abb6f10a 176 &sc->thread, TDF_STOPREQ|TDF_INTTHREAD, cpu,
92b561b7 177 "softclock %d", cpu);
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178#if 0
179 /*
180 * Do not make the thread preemptable until we clean up all
181 * the splsoftclock() calls in the system. Since the threads
182 * are no longer operated as a software interrupt, the
183 * splsoftclock() calls will not have any effect on them.
184 */
185 sc->thread.td_preemptable = lwkt_preempt;
186#endif
187 }
188}
189
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190/*
191 * Must occur after ncpus has been initialized.
192 */
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193SYSINIT(softclock_setup, SI_BOOT2_SOFTCLOCK, SI_ORDER_SECOND,
194 swi_softclock_setup, NULL);
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195
196/*
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197 * This routine is called from the hardclock() (basically a FASTint/IPI) on
198 * each cpu in the system. sc->curticks is this cpu's notion of the timebase.
199 * It IS NOT NECESSARILY SYNCHRONIZED WITH 'ticks'! sc->softticks is where
200 * the callwheel is currently indexed.
201 *
202 * WARNING! The MP lock is not necessarily held on call, nor can it be
203 * safely obtained.
204 *
205 * sc->softticks is adjusted by either this routine or our helper thread
206 * depending on whether the helper thread is running or not.
984263bc 207 */
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208void
209hardclock_softtick(globaldata_t gd)
210{
211 softclock_pcpu_t sc;
212
213 sc = &softclock_pcpu_ary[gd->gd_cpuid];
214 ++sc->curticks;
215 if (sc->isrunning)
216 return;
217 if (sc->softticks == sc->curticks) {
218 /*
219 * in sync, only wakeup the thread if there is something to
220 * do.
221 */
222 if (TAILQ_FIRST(&sc->callwheel[sc->softticks & callwheelmask]))
223 {
224 sc->isrunning = 1;
225 lwkt_schedule(&sc->thread);
226 } else {
227 ++sc->softticks;
228 }
229 } else {
230 /*
231 * out of sync, wakeup the thread unconditionally so it can
232 * catch up.
233 */
234 sc->isrunning = 1;
235 lwkt_schedule(&sc->thread);
236 }
237}
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238
239/*
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240 * This procedure is the main loop of our per-cpu helper thread. The
241 * sc->isrunning flag prevents us from racing hardclock_softtick() and
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242 * a critical section is sufficient to interlock sc->curticks and protect
243 * us from remote IPI's / list removal.
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244 *
245 * The thread starts with the MP lock held and not in a critical section.
246 * The loop itself is MP safe while individual callbacks may or may not
247 * be, so we obtain or release the MP lock as appropriate.
984263bc 248 */
ef0fdad1 249static void
92b561b7 250softclock_handler(void *arg)
984263bc 251{
92b561b7 252 softclock_pcpu_t sc;
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253 struct callout *c;
254 struct callout_tailq *bucket;
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255 void (*c_func)(void *);
256 void *c_arg;
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257#ifdef SMP
258 int mpsafe = 0;
259#endif
260
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261 lwkt_setpri_self(TDPRI_SOFT_NORM);
262
92b561b7 263 sc = arg;
88c4d2f6 264 crit_enter();
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265loop:
266 while (sc->softticks != (int)(sc->curticks + 1)) {
267 bucket = &sc->callwheel[sc->softticks & callwheelmask];
268
269 for (c = TAILQ_FIRST(bucket); c; c = sc->next) {
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270 if (c->c_time != sc->softticks) {
271 sc->next = TAILQ_NEXT(c, c_links.tqe);
92b561b7 272 continue;
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273 }
274#ifdef SMP
275 if (c->c_flags & CALLOUT_MPSAFE) {
276 if (mpsafe == 0) {
277 mpsafe = 1;
278 rel_mplock();
279 }
280 } else {
281 /*
282 * The request might be removed while we
283 * are waiting to get the MP lock. If it
284 * was removed sc->next will point to the
285 * next valid request or NULL, loop up.
286 */
287 if (mpsafe) {
288 mpsafe = 0;
289 sc->next = c;
290 get_mplock();
291 if (c != sc->next)
292 continue;
293 }
294 }
295#endif
296 sc->next = TAILQ_NEXT(c, c_links.tqe);
92b561b7 297 TAILQ_REMOVE(bucket, c, c_links.tqe);
4ac1a4cd 298
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299 c_func = c->c_func;
300 c_arg = c->c_arg;
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301 c->c_func = NULL;
302 KKASSERT(c->c_flags & CALLOUT_DID_INIT);
7eb3b2ae 303 c->c_flags &= ~CALLOUT_PENDING;
92b561b7 304 crit_exit();
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305 c_func(c_arg);
306 crit_enter();
307 /* NOTE: list may have changed */
984263bc 308 }
92b561b7 309 ++sc->softticks;
984263bc 310 }
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311 sc->isrunning = 0;
312 lwkt_deschedule_self(&sc->thread); /* == curthread */
313 lwkt_switch();
314 goto loop;
315 /* NOT REACHED */
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316}
317
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318/*
319 * New interface; clients allocate their own callout structures.
320 *
321 * callout_reset() - establish or change a timeout
322 * callout_stop() - disestablish a timeout
323 * callout_init() - initialize a callout structure so that it can
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324 * safely be passed to callout_reset() and callout_stop()
325 * callout_init_mp() - same but any installed functions must be MP safe.
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326 *
327 * <sys/callout.h> defines three convenience macros:
328 *
329 * callout_active() - returns truth if callout has not been serviced
330 * callout_pending() - returns truth if callout is still waiting for timeout
331 * callout_deactivate() - marks the callout as having been serviced
332 */
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333
334/*
335 * Start or restart a timeout. Install the callout structure in the
336 * callwheel. Callers may legally pass any value, even if 0 or negative,
337 * but since the sc->curticks index may have already been processed a
338 * minimum timeout of 1 tick will be enforced.
339 *
340 * The callout is installed on and will be processed on the current cpu's
341 * callout wheel.
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342 *
343 * WARNING! This function may be called from any cpu but the caller must
344 * serialize callout_stop() and callout_reset() calls on the passed
345 * structure regardless of cpu.
92b561b7 346 */
984263bc 347void
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348callout_reset(struct callout *c, int to_ticks, void (*ftn)(void *),
349 void *arg)
984263bc 350{
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351 softclock_pcpu_t sc;
352 globaldata_t gd;
353
354#ifdef INVARIANTS
355 if ((c->c_flags & CALLOUT_DID_INIT) == 0) {
356 callout_init(c);
6ea70f76 357 kprintf(
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358 "callout_reset(%p) from %p: callout was not initialized\n",
359 c, ((int **)&c)[-1]);
1e5fb84b 360 print_backtrace();
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361 }
362#endif
363 gd = mycpu;
364 sc = &softclock_pcpu_ary[gd->gd_cpuid];
365 crit_enter_gd(gd);
984263bc 366
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367 if (c->c_flags & CALLOUT_PENDING)
368 callout_stop(c);
369
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370 if (to_ticks <= 0)
371 to_ticks = 1;
372
373 c->c_arg = arg;
374 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
375 c->c_func = ftn;
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376 c->c_time = sc->curticks + to_ticks;
377#ifdef SMP
378 c->c_gd = gd;
379#endif
380
381 TAILQ_INSERT_TAIL(&sc->callwheel[c->c_time & callwheelmask],
984263bc 382 c, c_links.tqe);
92b561b7 383 crit_exit_gd(gd);
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384}
385
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386/*
387 * Stop a running timer. WARNING! If called on a cpu other then the one
388 * the callout was started on this function will liveloop on its IPI to
389 * the target cpu to process the request. It is possible for the callout
390 * to execute in that case.
391 *
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392 * WARNING! This function may be called from any cpu but the caller must
393 * serialize callout_stop() and callout_reset() calls on the passed
394 * structure regardless of cpu.
395 *
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396 * WARNING! This routine may be called from an IPI
397 */
984263bc 398int
216ffe3f 399callout_stop(struct callout *c)
984263bc 400{
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401 globaldata_t gd = mycpu;
402#ifdef SMP
403 globaldata_t tgd;
404#endif
405 softclock_pcpu_t sc;
406
407#ifdef INVARIANTS
408 if ((c->c_flags & CALLOUT_DID_INIT) == 0) {
409 callout_init(c);
6ea70f76 410 kprintf(
634056cf 411 "callout_stop(%p) from %p: callout was not initialized\n",
92b561b7 412 c, ((int **)&c)[-1]);
1e5fb84b 413 print_backtrace();
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414 }
415#endif
416 crit_enter_gd(gd);
984263bc 417
984263bc 418 /*
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419 * Don't attempt to delete a callout that's not on the queue. The
420 * callout may not have a cpu assigned to it. Callers do not have
421 * to be on the issuing cpu but must still serialize access to the
422 * callout structure.
423 *
424 * We are not cpu-localized here and cannot safely modify the
425 * flags field in the callout structure. Note that most of the
426 * time CALLOUT_ACTIVE will be 0 if CALLOUT_PENDING is also 0.
427 *
428 * If we race another cpu's dispatch of this callout it is possible
429 * for CALLOUT_ACTIVE to be set with CALLOUT_PENDING unset. This
430 * will cause us to fall through and synchronize with the other
431 * cpu.
984263bc 432 */
92b561b7 433 if ((c->c_flags & CALLOUT_PENDING) == 0) {
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434#ifdef SMP
435 if ((c->c_flags & CALLOUT_ACTIVE) == 0) {
436 crit_exit_gd(gd);
437 return (0);
438 }
439 if (c->c_gd == NULL || c->c_gd == gd) {
440 c->c_flags &= ~CALLOUT_ACTIVE;
441 crit_exit_gd(gd);
442 return (0);
443 }
444 /* fall-through to the cpu-localization code. */
445#else
984263bc 446 c->c_flags &= ~CALLOUT_ACTIVE;
92b561b7 447 crit_exit_gd(gd);
984263bc 448 return (0);
7ac978db 449#endif
984263bc 450 }
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451#ifdef SMP
452 if ((tgd = c->c_gd) != gd) {
453 /*
454 * If the callout is owned by a different CPU we have to
455 * execute the function synchronously on the target cpu.
456 */
457 int seq;
458
35238fa5 459 cpu_ccfence(); /* don't let tgd alias c_gd */
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460 seq = lwkt_send_ipiq(tgd, (void *)callout_stop, c);
461 lwkt_wait_ipiq(tgd, seq);
462 } else
463#endif
464 {
465 /*
466 * If the callout is owned by the same CPU we can
467 * process it directly, but if we are racing our helper
468 * thread (sc->next), we have to adjust sc->next. The
469 * race is interlocked by a critical section.
470 */
471 sc = &softclock_pcpu_ary[gd->gd_cpuid];
984263bc 472
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473 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
474 if (sc->next == c)
475 sc->next = TAILQ_NEXT(c, c_links.tqe);
476
477 TAILQ_REMOVE(&sc->callwheel[c->c_time & callwheelmask],
478 c, c_links.tqe);
479 c->c_func = NULL;
984263bc 480 }
92b561b7 481 crit_exit_gd(gd);
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482 return (1);
483}
484
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485/*
486 * Prepare a callout structure for use by callout_reset() and/or
487 * callout_stop(). The MP version of this routine requires that the callback
986d8a07 488 * function installed by callout_reset() be MP safe.
92b561b7 489 */
984263bc 490void
216ffe3f 491callout_init(struct callout *c)
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492{
493 bzero(c, sizeof *c);
92b561b7 494 c->c_flags = CALLOUT_DID_INIT;
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495}
496
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497void
498callout_init_mp(struct callout *c)
ef0fdad1 499{
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500 callout_init(c);
501 c->c_flags |= CALLOUT_MPSAFE;
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502}
503
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504/* What, are you joking? This is nuts! -Matt */
505#if 0
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506#ifdef APM_FIXUP_CALLTODO
507/*
508 * Adjust the kernel calltodo timeout list. This routine is used after
509 * an APM resume to recalculate the calltodo timer list values with the
510 * number of hz's we have been sleeping. The next hardclock() will detect
511 * that there are fired timers and run softclock() to execute them.
512 *
513 * Please note, I have not done an exhaustive analysis of what code this
514 * might break. I am motivated to have my select()'s and alarm()'s that
515 * have expired during suspend firing upon resume so that the applications
516 * which set the timer can do the maintanence the timer was for as close
517 * as possible to the originally intended time. Testing this code for a
518 * week showed that resuming from a suspend resulted in 22 to 25 timers
519 * firing, which seemed independant on whether the suspend was 2 hours or
520 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu>
521 */
522void
216ffe3f 523adjust_timeout_calltodo(struct timeval *time_change)
984263bc 524{
1fd87d54 525 struct callout *p;
984263bc 526 unsigned long delta_ticks;
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527
528 /*
529 * How many ticks were we asleep?
530 * (stolen from tvtohz()).
531 */
532
533 /* Don't do anything */
534 if (time_change->tv_sec < 0)
535 return;
536 else if (time_change->tv_sec <= LONG_MAX / 1000000)
537 delta_ticks = (time_change->tv_sec * 1000000 +
538 time_change->tv_usec + (tick - 1)) / tick + 1;
539 else if (time_change->tv_sec <= LONG_MAX / hz)
540 delta_ticks = time_change->tv_sec * hz +
541 (time_change->tv_usec + (tick - 1)) / tick + 1;
542 else
543 delta_ticks = LONG_MAX;
544
545 if (delta_ticks > INT_MAX)
546 delta_ticks = INT_MAX;
547
548 /*
549 * Now rip through the timer calltodo list looking for timers
550 * to expire.
551 */
552
553 /* don't collide with softclock() */
e43a034f 554 crit_enter();
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555 for (p = calltodo.c_next; p != NULL; p = p->c_next) {
556 p->c_time -= delta_ticks;
557
558 /* Break if the timer had more time on it than delta_ticks */
559 if (p->c_time > 0)
560 break;
561
562 /* take back the ticks the timer didn't use (p->c_time <= 0) */
563 delta_ticks = -p->c_time;
564 }
e43a034f 565 crit_exit();
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566
567 return;
568}
569#endif /* APM_FIXUP_CALLTODO */
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570#endif
571