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 * 4. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * From: @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
35 */
36
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD: releng/9.0/sys/kern/kern_timeout.c 225057 2011-08-21 10:52:50Z attilio $");
39
40 #include "opt_kdtrace.h"
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/bus.h>
45 #include <sys/callout.h>
46 #include <sys/condvar.h>
47 #include <sys/interrupt.h>
48 #include <sys/kernel.h>
49 #include <sys/ktr.h>
50 #include <sys/lock.h>
51 #include <sys/malloc.h>
52 #include <sys/mutex.h>
53 #include <sys/proc.h>
54 #include <sys/sdt.h>
55 #include <sys/sleepqueue.h>
56 #include <sys/sysctl.h>
57 #include <sys/smp.h>
58
59 #ifdef SMP
60 #include <machine/cpu.h>
61 #endif
62
63 SDT_PROVIDER_DEFINE(callout_execute);
64 SDT_PROBE_DEFINE(callout_execute, kernel, , callout_start, callout-start);
65 SDT_PROBE_ARGTYPE(callout_execute, kernel, , callout_start, 0,
66 "struct callout *");
67 SDT_PROBE_DEFINE(callout_execute, kernel, , callout_end, callout-end);
68 SDT_PROBE_ARGTYPE(callout_execute, kernel, , callout_end, 0,
69 "struct callout *");
70
71 static int avg_depth;
72 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0,
73 "Average number of items examined per softclock call. Units = 1/1000");
74 static int avg_gcalls;
75 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0,
76 "Average number of Giant callouts made per softclock call. Units = 1/1000");
77 static int avg_lockcalls;
78 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0,
79 "Average number of lock callouts made per softclock call. Units = 1/1000");
80 static int avg_mpcalls;
81 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0,
82 "Average number of MP callouts made per softclock call. Units = 1/1000");
83 /*
84 * TODO:
85 * allocate more timeout table slots when table overflows.
86 */
87 int callwheelsize, callwheelbits, callwheelmask;
88
89 /*
90 * The callout cpu migration entity represents informations necessary for
91 * describing the migrating callout to the new callout cpu.
92 * The cached informations are very important for deferring migration when
93 * the migrating callout is already running.
94 */
95 struct cc_mig_ent {
96 #ifdef SMP
97 void (*ce_migration_func)(void *);
98 void *ce_migration_arg;
99 int ce_migration_cpu;
100 int ce_migration_ticks;
101 #endif
102 };
103
104 /*
105 * There is one struct callout_cpu per cpu, holding all relevant
106 * state for the callout processing thread on the individual CPU.
107 * In particular:
108 * cc_ticks is incremented once per tick in callout_cpu().
109 * It tracks the global 'ticks' but in a way that the individual
110 * threads should not worry about races in the order in which
111 * hardclock() and hardclock_cpu() run on the various CPUs.
112 * cc_softclock is advanced in callout_cpu() to point to the
113 * first entry in cc_callwheel that may need handling. In turn,
114 * a softclock() is scheduled so it can serve the various entries i
115 * such that cc_softclock <= i <= cc_ticks .
116 * XXX maybe cc_softclock and cc_ticks should be volatile ?
117 *
118 * cc_ticks is also used in callout_reset_cpu() to determine
119 * when the callout should be served.
120 */
121 struct callout_cpu {
122 struct cc_mig_ent cc_migrating_entity;
123 struct mtx cc_lock;
124 struct callout *cc_callout;
125 struct callout_tailq *cc_callwheel;
126 struct callout_list cc_callfree;
127 struct callout *cc_next;
128 struct callout *cc_curr;
129 void *cc_cookie;
130 int cc_ticks;
131 int cc_softticks;
132 int cc_cancel;
133 int cc_waiting;
134 int cc_firsttick;
135 };
136
137 #ifdef SMP
138 #define cc_migration_func cc_migrating_entity.ce_migration_func
139 #define cc_migration_arg cc_migrating_entity.ce_migration_arg
140 #define cc_migration_cpu cc_migrating_entity.ce_migration_cpu
141 #define cc_migration_ticks cc_migrating_entity.ce_migration_ticks
142
143 struct callout_cpu cc_cpu[MAXCPU];
144 #define CPUBLOCK MAXCPU
145 #define CC_CPU(cpu) (&cc_cpu[(cpu)])
146 #define CC_SELF() CC_CPU(PCPU_GET(cpuid))
147 #else
148 struct callout_cpu cc_cpu;
149 #define CC_CPU(cpu) &cc_cpu
150 #define CC_SELF() &cc_cpu
151 #endif
152 #define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock)
153 #define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock)
154 #define CC_LOCK_ASSERT(cc) mtx_assert(&(cc)->cc_lock, MA_OWNED)
155
156 static int timeout_cpu;
157 void (*callout_new_inserted)(int cpu, int ticks) = NULL;
158
159 MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures");
160
161 /**
162 * Locked by cc_lock:
163 * cc_curr - If a callout is in progress, it is curr_callout.
164 * If curr_callout is non-NULL, threads waiting in
165 * callout_drain() will be woken up as soon as the
166 * relevant callout completes.
167 * cc_cancel - Changing to 1 with both callout_lock and c_lock held
168 * guarantees that the current callout will not run.
169 * The softclock() function sets this to 0 before it
170 * drops callout_lock to acquire c_lock, and it calls
171 * the handler only if curr_cancelled is still 0 after
172 * c_lock is successfully acquired.
173 * cc_waiting - If a thread is waiting in callout_drain(), then
174 * callout_wait is nonzero. Set only when
175 * curr_callout is non-NULL.
176 */
177
178 /*
179 * Resets the migration entity tied to a specific callout cpu.
180 */
181 static void
182 cc_cme_cleanup(struct callout_cpu *cc)
183 {
184
185 #ifdef SMP
186 cc->cc_migration_cpu = CPUBLOCK;
187 cc->cc_migration_ticks = 0;
188 cc->cc_migration_func = NULL;
189 cc->cc_migration_arg = NULL;
190 #endif
191 }
192
193 /*
194 * Checks if migration is requested by a specific callout cpu.
195 */
196 static int
197 cc_cme_migrating(struct callout_cpu *cc)
198 {
199
200 #ifdef SMP
201 return (cc->cc_migration_cpu != CPUBLOCK);
202 #else
203 return (0);
204 #endif
205 }
206
207 /*
208 * kern_timeout_callwheel_alloc() - kernel low level callwheel initialization
209 *
210 * This code is called very early in the kernel initialization sequence,
211 * and may be called more then once.
212 */
213 caddr_t
214 kern_timeout_callwheel_alloc(caddr_t v)
215 {
216 struct callout_cpu *cc;
217
218 timeout_cpu = PCPU_GET(cpuid);
219 cc = CC_CPU(timeout_cpu);
220 /*
221 * Calculate callout wheel size
222 */
223 for (callwheelsize = 1, callwheelbits = 0;
224 callwheelsize < ncallout;
225 callwheelsize <<= 1, ++callwheelbits)
226 ;
227 callwheelmask = callwheelsize - 1;
228
229 cc->cc_callout = (struct callout *)v;
230 v = (caddr_t)(cc->cc_callout + ncallout);
231 cc->cc_callwheel = (struct callout_tailq *)v;
232 v = (caddr_t)(cc->cc_callwheel + callwheelsize);
233 return(v);
234 }
235
236 static void
237 callout_cpu_init(struct callout_cpu *cc)
238 {
239 struct callout *c;
240 int i;
241
242 mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN | MTX_RECURSE);
243 SLIST_INIT(&cc->cc_callfree);
244 for (i = 0; i < callwheelsize; i++) {
245 TAILQ_INIT(&cc->cc_callwheel[i]);
246 }
247 cc_cme_cleanup(cc);
248 if (cc->cc_callout == NULL)
249 return;
250 for (i = 0; i < ncallout; i++) {
251 c = &cc->cc_callout[i];
252 callout_init(c, 0);
253 c->c_flags = CALLOUT_LOCAL_ALLOC;
254 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle);
255 }
256 }
257
258 #ifdef SMP
259 /*
260 * Switches the cpu tied to a specific callout.
261 * The function expects a locked incoming callout cpu and returns with
262 * locked outcoming callout cpu.
263 */
264 static struct callout_cpu *
265 callout_cpu_switch(struct callout *c, struct callout_cpu *cc, int new_cpu)
266 {
267 struct callout_cpu *new_cc;
268
269 MPASS(c != NULL && cc != NULL);
270 CC_LOCK_ASSERT(cc);
271
272 /*
273 * Avoid interrupts and preemption firing after the callout cpu
274 * is blocked in order to avoid deadlocks as the new thread
275 * may be willing to acquire the callout cpu lock.
276 */
277 c->c_cpu = CPUBLOCK;
278 spinlock_enter();
279 CC_UNLOCK(cc);
280 new_cc = CC_CPU(new_cpu);
281 CC_LOCK(new_cc);
282 spinlock_exit();
283 c->c_cpu = new_cpu;
284 return (new_cc);
285 }
286 #endif
287
288 /*
289 * kern_timeout_callwheel_init() - initialize previously reserved callwheel
290 * space.
291 *
292 * This code is called just once, after the space reserved for the
293 * callout wheel has been finalized.
294 */
295 void
296 kern_timeout_callwheel_init(void)
297 {
298 callout_cpu_init(CC_CPU(timeout_cpu));
299 }
300
301 /*
302 * Start standard softclock thread.
303 */
304 static void
305 start_softclock(void *dummy)
306 {
307 struct callout_cpu *cc;
308 #ifdef SMP
309 int cpu;
310 #endif
311
312 cc = CC_CPU(timeout_cpu);
313 if (swi_add(&clk_intr_event, "clock", softclock, cc, SWI_CLOCK,
314 INTR_MPSAFE, &cc->cc_cookie))
315 panic("died while creating standard software ithreads");
316 #ifdef SMP
317 CPU_FOREACH(cpu) {
318 if (cpu == timeout_cpu)
319 continue;
320 cc = CC_CPU(cpu);
321 if (swi_add(NULL, "clock", softclock, cc, SWI_CLOCK,
322 INTR_MPSAFE, &cc->cc_cookie))
323 panic("died while creating standard software ithreads");
324 cc->cc_callout = NULL; /* Only cpu0 handles timeout(). */
325 cc->cc_callwheel = malloc(
326 sizeof(struct callout_tailq) * callwheelsize, M_CALLOUT,
327 M_WAITOK);
328 callout_cpu_init(cc);
329 }
330 #endif
331 }
332
333 SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL);
334
335 void
336 callout_tick(void)
337 {
338 struct callout_cpu *cc;
339 int need_softclock;
340 int bucket;
341
342 /*
343 * Process callouts at a very low cpu priority, so we don't keep the
344 * relatively high clock interrupt priority any longer than necessary.
345 */
346 need_softclock = 0;
347 cc = CC_SELF();
348 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET);
349 cc->cc_firsttick = cc->cc_ticks = ticks;
350 for (; (cc->cc_softticks - cc->cc_ticks) <= 0; cc->cc_softticks++) {
351 bucket = cc->cc_softticks & callwheelmask;
352 if (!TAILQ_EMPTY(&cc->cc_callwheel[bucket])) {
353 need_softclock = 1;
354 break;
355 }
356 }
357 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET);
358 /*
359 * swi_sched acquires the thread lock, so we don't want to call it
360 * with cc_lock held; incorrect locking order.
361 */
362 if (need_softclock)
363 swi_sched(cc->cc_cookie, 0);
364 }
365
366 int
367 callout_tickstofirst(int limit)
368 {
369 struct callout_cpu *cc;
370 struct callout *c;
371 struct callout_tailq *sc;
372 int curticks;
373 int skip = 1;
374
375 cc = CC_SELF();
376 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET);
377 curticks = cc->cc_ticks;
378 while( skip < ncallout && skip < limit ) {
379 sc = &cc->cc_callwheel[ (curticks+skip) & callwheelmask ];
380 /* search scanning ticks */
381 TAILQ_FOREACH( c, sc, c_links.tqe ){
382 if (c->c_time - curticks <= ncallout)
383 goto out;
384 }
385 skip++;
386 }
387 out:
388 cc->cc_firsttick = curticks + skip;
389 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET);
390 return (skip);
391 }
392
393 static struct callout_cpu *
394 callout_lock(struct callout *c)
395 {
396 struct callout_cpu *cc;
397 int cpu;
398
399 for (;;) {
400 cpu = c->c_cpu;
401 #ifdef SMP
402 if (cpu == CPUBLOCK) {
403 while (c->c_cpu == CPUBLOCK)
404 cpu_spinwait();
405 continue;
406 }
407 #endif
408 cc = CC_CPU(cpu);
409 CC_LOCK(cc);
410 if (cpu == c->c_cpu)
411 break;
412 CC_UNLOCK(cc);
413 }
414 return (cc);
415 }
416
417 static void
418 callout_cc_add(struct callout *c, struct callout_cpu *cc, int to_ticks,
419 void (*func)(void *), void *arg, int cpu)
420 {
421
422 CC_LOCK_ASSERT(cc);
423
424 if (to_ticks <= 0)
425 to_ticks = 1;
426 c->c_arg = arg;
427 c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
428 c->c_func = func;
429 c->c_time = ticks + to_ticks;
430 TAILQ_INSERT_TAIL(&cc->cc_callwheel[c->c_time & callwheelmask],
431 c, c_links.tqe);
432 if ((c->c_time - cc->cc_firsttick) < 0 &&
433 callout_new_inserted != NULL) {
434 cc->cc_firsttick = c->c_time;
435 (*callout_new_inserted)(cpu,
436 to_ticks + (ticks - cc->cc_ticks));
437 }
438 }
439
440 /*
441 * The callout mechanism is based on the work of Adam M. Costello and
442 * George Varghese, published in a technical report entitled "Redesigning
443 * the BSD Callout and Timer Facilities" and modified slightly for inclusion
444 * in FreeBSD by Justin T. Gibbs. The original work on the data structures
445 * used in this implementation was published by G. Varghese and T. Lauck in
446 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
447 * the Efficient Implementation of a Timer Facility" in the Proceedings of
448 * the 11th ACM Annual Symposium on Operating Systems Principles,
449 * Austin, Texas Nov 1987.
450 */
451
452 /*
453 * Software (low priority) clock interrupt.
454 * Run periodic events from timeout queue.
455 */
456 void
457 softclock(void *arg)
458 {
459 struct callout_cpu *cc;
460 struct callout *c;
461 struct callout_tailq *bucket;
462 int curticks;
463 int steps; /* #steps since we last allowed interrupts */
464 int depth;
465 int mpcalls;
466 int lockcalls;
467 int gcalls;
468 #ifdef DIAGNOSTIC
469 struct bintime bt1, bt2;
470 struct timespec ts2;
471 static uint64_t maxdt = 36893488147419102LL; /* 2 msec */
472 static timeout_t *lastfunc;
473 #endif
474
475 #ifndef MAX_SOFTCLOCK_STEPS
476 #define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */
477 #endif /* MAX_SOFTCLOCK_STEPS */
478
479 mpcalls = 0;
480 lockcalls = 0;
481 gcalls = 0;
482 depth = 0;
483 steps = 0;
484 cc = (struct callout_cpu *)arg;
485 CC_LOCK(cc);
486 while (cc->cc_softticks - 1 != cc->cc_ticks) {
487 /*
488 * cc_softticks may be modified by hard clock, so cache
489 * it while we work on a given bucket.
490 */
491 curticks = cc->cc_softticks;
492 cc->cc_softticks++;
493 bucket = &cc->cc_callwheel[curticks & callwheelmask];
494 c = TAILQ_FIRST(bucket);
495 while (c) {
496 depth++;
497 if (c->c_time != curticks) {
498 c = TAILQ_NEXT(c, c_links.tqe);
499 ++steps;
500 if (steps >= MAX_SOFTCLOCK_STEPS) {
501 cc->cc_next = c;
502 /* Give interrupts a chance. */
503 CC_UNLOCK(cc);
504 ; /* nothing */
505 CC_LOCK(cc);
506 c = cc->cc_next;
507 steps = 0;
508 }
509 } else {
510 void (*c_func)(void *);
511 void *c_arg;
512 struct lock_class *class;
513 struct lock_object *c_lock;
514 int c_flags, sharedlock;
515
516 cc->cc_next = TAILQ_NEXT(c, c_links.tqe);
517 TAILQ_REMOVE(bucket, c, c_links.tqe);
518 class = (c->c_lock != NULL) ?
519 LOCK_CLASS(c->c_lock) : NULL;
520 sharedlock = (c->c_flags & CALLOUT_SHAREDLOCK) ?
521 0 : 1;
522 c_lock = c->c_lock;
523 c_func = c->c_func;
524 c_arg = c->c_arg;
525 c_flags = c->c_flags;
526 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
527 c->c_flags = CALLOUT_LOCAL_ALLOC;
528 } else {
529 c->c_flags =
530 (c->c_flags & ~CALLOUT_PENDING);
531 }
532 cc->cc_curr = c;
533 cc->cc_cancel = 0;
534 CC_UNLOCK(cc);
535 if (c_lock != NULL) {
536 class->lc_lock(c_lock, sharedlock);
537 /*
538 * The callout may have been cancelled
539 * while we switched locks.
540 */
541 if (cc->cc_cancel) {
542 class->lc_unlock(c_lock);
543 goto skip;
544 }
545 /* The callout cannot be stopped now. */
546 cc->cc_cancel = 1;
547
548 if (c_lock == &Giant.lock_object) {
549 gcalls++;
550 CTR3(KTR_CALLOUT,
551 "callout %p func %p arg %p",
552 c, c_func, c_arg);
553 } else {
554 lockcalls++;
555 CTR3(KTR_CALLOUT, "callout lock"
556 " %p func %p arg %p",
557 c, c_func, c_arg);
558 }
559 } else {
560 mpcalls++;
561 CTR3(KTR_CALLOUT,
562 "callout mpsafe %p func %p arg %p",
563 c, c_func, c_arg);
564 }
565 #ifdef DIAGNOSTIC
566 binuptime(&bt1);
567 #endif
568 THREAD_NO_SLEEPING();
569 SDT_PROBE(callout_execute, kernel, ,
570 callout_start, c, 0, 0, 0, 0);
571 c_func(c_arg);
572 SDT_PROBE(callout_execute, kernel, ,
573 callout_end, c, 0, 0, 0, 0);
574 THREAD_SLEEPING_OK();
575 #ifdef DIAGNOSTIC
576 binuptime(&bt2);
577 bintime_sub(&bt2, &bt1);
578 if (bt2.frac > maxdt) {
579 if (lastfunc != c_func ||
580 bt2.frac > maxdt * 2) {
581 bintime2timespec(&bt2, &ts2);
582 printf(
583 "Expensive timeout(9) function: %p(%p) %jd.%09ld s\n",
584 c_func, c_arg,
585 (intmax_t)ts2.tv_sec,
586 ts2.tv_nsec);
587 }
588 maxdt = bt2.frac;
589 lastfunc = c_func;
590 }
591 #endif
592 CTR1(KTR_CALLOUT, "callout %p finished", c);
593 if ((c_flags & CALLOUT_RETURNUNLOCKED) == 0)
594 class->lc_unlock(c_lock);
595 skip:
596 CC_LOCK(cc);
597 /*
598 * If the current callout is locally
599 * allocated (from timeout(9))
600 * then put it on the freelist.
601 *
602 * Note: we need to check the cached
603 * copy of c_flags because if it was not
604 * local, then it's not safe to deref the
605 * callout pointer.
606 */
607 if (c_flags & CALLOUT_LOCAL_ALLOC) {
608 KASSERT(c->c_flags ==
609 CALLOUT_LOCAL_ALLOC,
610 ("corrupted callout"));
611 c->c_func = NULL;
612 SLIST_INSERT_HEAD(&cc->cc_callfree, c,
613 c_links.sle);
614 }
615 cc->cc_curr = NULL;
616 if (cc->cc_waiting) {
617
618 /*
619 * There is someone waiting for the
620 * callout to complete.
621 * If the callout was scheduled for
622 * migration just cancel it.
623 */
624 if (cc_cme_migrating(cc))
625 cc_cme_cleanup(cc);
626 cc->cc_waiting = 0;
627 CC_UNLOCK(cc);
628 wakeup(&cc->cc_waiting);
629 CC_LOCK(cc);
630 } else if (cc_cme_migrating(cc)) {
631 #ifdef SMP
632 struct callout_cpu *new_cc;
633 void (*new_func)(void *);
634 void *new_arg;
635 int new_cpu, new_ticks;
636
637 /*
638 * If the callout was scheduled for
639 * migration just perform it now.
640 */
641 new_cpu = cc->cc_migration_cpu;
642 new_ticks = cc->cc_migration_ticks;
643 new_func = cc->cc_migration_func;
644 new_arg = cc->cc_migration_arg;
645 cc_cme_cleanup(cc);
646
647 /*
648 * It should be assert here that the
649 * callout is not destroyed but that
650 * is not easy.
651 */
652 new_cc = callout_cpu_switch(c, cc,
653 new_cpu);
654 callout_cc_add(c, new_cc, new_ticks,
655 new_func, new_arg, new_cpu);
656 CC_UNLOCK(new_cc);
657 CC_LOCK(cc);
658 #else
659 panic("migration should not happen");
660 #endif
661 }
662 steps = 0;
663 c = cc->cc_next;
664 }
665 }
666 }
667 avg_depth += (depth * 1000 - avg_depth) >> 8;
668 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8;
669 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8;
670 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8;
671 cc->cc_next = NULL;
672 CC_UNLOCK(cc);
673 }
674
675 /*
676 * timeout --
677 * Execute a function after a specified length of time.
678 *
679 * untimeout --
680 * Cancel previous timeout function call.
681 *
682 * callout_handle_init --
683 * Initialize a handle so that using it with untimeout is benign.
684 *
685 * See AT&T BCI Driver Reference Manual for specification. This
686 * implementation differs from that one in that although an
687 * identification value is returned from timeout, the original
688 * arguments to timeout as well as the identifier are used to
689 * identify entries for untimeout.
690 */
691 struct callout_handle
692 timeout(ftn, arg, to_ticks)
693 timeout_t *ftn;
694 void *arg;
695 int to_ticks;
696 {
697 struct callout_cpu *cc;
698 struct callout *new;
699 struct callout_handle handle;
700
701 cc = CC_CPU(timeout_cpu);
702 CC_LOCK(cc);
703 /* Fill in the next free callout structure. */
704 new = SLIST_FIRST(&cc->cc_callfree);
705 if (new == NULL)
706 /* XXX Attempt to malloc first */
707 panic("timeout table full");
708 SLIST_REMOVE_HEAD(&cc->cc_callfree, c_links.sle);
709 callout_reset(new, to_ticks, ftn, arg);
710 handle.callout = new;
711 CC_UNLOCK(cc);
712
713 return (handle);
714 }
715
716 void
717 untimeout(ftn, arg, handle)
718 timeout_t *ftn;
719 void *arg;
720 struct callout_handle handle;
721 {
722 struct callout_cpu *cc;
723
724 /*
725 * Check for a handle that was initialized
726 * by callout_handle_init, but never used
727 * for a real timeout.
728 */
729 if (handle.callout == NULL)
730 return;
731
732 cc = callout_lock(handle.callout);
733 if (handle.callout->c_func == ftn && handle.callout->c_arg == arg)
734 callout_stop(handle.callout);
735 CC_UNLOCK(cc);
736 }
737
738 void
739 callout_handle_init(struct callout_handle *handle)
740 {
741 handle->callout = NULL;
742 }
743
744 /*
745 * New interface; clients allocate their own callout structures.
746 *
747 * callout_reset() - establish or change a timeout
748 * callout_stop() - disestablish a timeout
749 * callout_init() - initialize a callout structure so that it can
750 * safely be passed to callout_reset() and callout_stop()
751 *
752 * <sys/callout.h> defines three convenience macros:
753 *
754 * callout_active() - returns truth if callout has not been stopped,
755 * drained, or deactivated since the last time the callout was
756 * reset.
757 * callout_pending() - returns truth if callout is still waiting for timeout
758 * callout_deactivate() - marks the callout as having been serviced
759 */
760 int
761 callout_reset_on(struct callout *c, int to_ticks, void (*ftn)(void *),
762 void *arg, int cpu)
763 {
764 struct callout_cpu *cc;
765 int cancelled = 0;
766
767 /*
768 * Don't allow migration of pre-allocated callouts lest they
769 * become unbalanced.
770 */
771 if (c->c_flags & CALLOUT_LOCAL_ALLOC)
772 cpu = c->c_cpu;
773 cc = callout_lock(c);
774 if (cc->cc_curr == c) {
775 /*
776 * We're being asked to reschedule a callout which is
777 * currently in progress. If there is a lock then we
778 * can cancel the callout if it has not really started.
779 */
780 if (c->c_lock != NULL && !cc->cc_cancel)
781 cancelled = cc->cc_cancel = 1;
782 if (cc->cc_waiting) {
783 /*
784 * Someone has called callout_drain to kill this
785 * callout. Don't reschedule.
786 */
787 CTR4(KTR_CALLOUT, "%s %p func %p arg %p",
788 cancelled ? "cancelled" : "failed to cancel",
789 c, c->c_func, c->c_arg);
790 CC_UNLOCK(cc);
791 return (cancelled);
792 }
793 }
794 if (c->c_flags & CALLOUT_PENDING) {
795 if (cc->cc_next == c) {
796 cc->cc_next = TAILQ_NEXT(c, c_links.tqe);
797 }
798 TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c,
799 c_links.tqe);
800
801 cancelled = 1;
802 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
803 }
804
805 #ifdef SMP
806 /*
807 * If the callout must migrate try to perform it immediately.
808 * If the callout is currently running, just defer the migration
809 * to a more appropriate moment.
810 */
811 if (c->c_cpu != cpu) {
812 if (cc->cc_curr == c) {
813 cc->cc_migration_cpu = cpu;
814 cc->cc_migration_ticks = to_ticks;
815 cc->cc_migration_func = ftn;
816 cc->cc_migration_arg = arg;
817 CTR5(KTR_CALLOUT,
818 "migration of %p func %p arg %p in %d to %u deferred",
819 c, c->c_func, c->c_arg, to_ticks, cpu);
820 CC_UNLOCK(cc);
821 return (cancelled);
822 }
823 cc = callout_cpu_switch(c, cc, cpu);
824 }
825 #endif
826
827 callout_cc_add(c, cc, to_ticks, ftn, arg, cpu);
828 CTR5(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d",
829 cancelled ? "re" : "", c, c->c_func, c->c_arg, to_ticks);
830 CC_UNLOCK(cc);
831
832 return (cancelled);
833 }
834
835 /*
836 * Common idioms that can be optimized in the future.
837 */
838 int
839 callout_schedule_on(struct callout *c, int to_ticks, int cpu)
840 {
841 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu);
842 }
843
844 int
845 callout_schedule(struct callout *c, int to_ticks)
846 {
847 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu);
848 }
849
850 int
851 _callout_stop_safe(c, safe)
852 struct callout *c;
853 int safe;
854 {
855 struct callout_cpu *cc, *old_cc;
856 struct lock_class *class;
857 int use_lock, sq_locked;
858
859 /*
860 * Some old subsystems don't hold Giant while running a callout_stop(),
861 * so just discard this check for the moment.
862 */
863 if (!safe && c->c_lock != NULL) {
864 if (c->c_lock == &Giant.lock_object)
865 use_lock = mtx_owned(&Giant);
866 else {
867 use_lock = 1;
868 class = LOCK_CLASS(c->c_lock);
869 class->lc_assert(c->c_lock, LA_XLOCKED);
870 }
871 } else
872 use_lock = 0;
873
874 sq_locked = 0;
875 old_cc = NULL;
876 again:
877 cc = callout_lock(c);
878
879 /*
880 * If the callout was migrating while the callout cpu lock was
881 * dropped, just drop the sleepqueue lock and check the states
882 * again.
883 */
884 if (sq_locked != 0 && cc != old_cc) {
885 #ifdef SMP
886 CC_UNLOCK(cc);
887 sleepq_release(&old_cc->cc_waiting);
888 sq_locked = 0;
889 old_cc = NULL;
890 goto again;
891 #else
892 panic("migration should not happen");
893 #endif
894 }
895
896 /*
897 * If the callout isn't pending, it's not on the queue, so
898 * don't attempt to remove it from the queue. We can try to
899 * stop it by other means however.
900 */
901 if (!(c->c_flags & CALLOUT_PENDING)) {
902 c->c_flags &= ~CALLOUT_ACTIVE;
903
904 /*
905 * If it wasn't on the queue and it isn't the current
906 * callout, then we can't stop it, so just bail.
907 */
908 if (cc->cc_curr != c) {
909 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
910 c, c->c_func, c->c_arg);
911 CC_UNLOCK(cc);
912 if (sq_locked)
913 sleepq_release(&cc->cc_waiting);
914 return (0);
915 }
916
917 if (safe) {
918 /*
919 * The current callout is running (or just
920 * about to run) and blocking is allowed, so
921 * just wait for the current invocation to
922 * finish.
923 */
924 while (cc->cc_curr == c) {
925
926 /*
927 * Use direct calls to sleepqueue interface
928 * instead of cv/msleep in order to avoid
929 * a LOR between cc_lock and sleepqueue
930 * chain spinlocks. This piece of code
931 * emulates a msleep_spin() call actually.
932 *
933 * If we already have the sleepqueue chain
934 * locked, then we can safely block. If we
935 * don't already have it locked, however,
936 * we have to drop the cc_lock to lock
937 * it. This opens several races, so we
938 * restart at the beginning once we have
939 * both locks. If nothing has changed, then
940 * we will end up back here with sq_locked
941 * set.
942 */
943 if (!sq_locked) {
944 CC_UNLOCK(cc);
945 sleepq_lock(&cc->cc_waiting);
946 sq_locked = 1;
947 old_cc = cc;
948 goto again;
949 }
950
951 /*
952 * Migration could be cancelled here, but
953 * as long as it is still not sure when it
954 * will be packed up, just let softclock()
955 * take care of it.
956 */
957 cc->cc_waiting = 1;
958 DROP_GIANT();
959 CC_UNLOCK(cc);
960 sleepq_add(&cc->cc_waiting,
961 &cc->cc_lock.lock_object, "codrain",
962 SLEEPQ_SLEEP, 0);
963 sleepq_wait(&cc->cc_waiting, 0);
964 sq_locked = 0;
965 old_cc = NULL;
966
967 /* Reacquire locks previously released. */
968 PICKUP_GIANT();
969 CC_LOCK(cc);
970 }
971 } else if (use_lock && !cc->cc_cancel) {
972 /*
973 * The current callout is waiting for its
974 * lock which we hold. Cancel the callout
975 * and return. After our caller drops the
976 * lock, the callout will be skipped in
977 * softclock().
978 */
979 cc->cc_cancel = 1;
980 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
981 c, c->c_func, c->c_arg);
982 KASSERT(!cc_cme_migrating(cc),
983 ("callout wrongly scheduled for migration"));
984 CC_UNLOCK(cc);
985 KASSERT(!sq_locked, ("sleepqueue chain locked"));
986 return (1);
987 }
988 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
989 c, c->c_func, c->c_arg);
990 CC_UNLOCK(cc);
991 KASSERT(!sq_locked, ("sleepqueue chain still locked"));
992 return (0);
993 }
994 if (sq_locked)
995 sleepq_release(&cc->cc_waiting);
996
997 c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
998
999 if (cc->cc_next == c) {
1000 cc->cc_next = TAILQ_NEXT(c, c_links.tqe);
1001 }
1002 TAILQ_REMOVE(&cc->cc_callwheel[c->c_time & callwheelmask], c,
1003 c_links.tqe);
1004
1005 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
1006 c, c->c_func, c->c_arg);
1007
1008 if (c->c_flags & CALLOUT_LOCAL_ALLOC) {
1009 c->c_func = NULL;
1010 SLIST_INSERT_HEAD(&cc->cc_callfree, c, c_links.sle);
1011 }
1012 CC_UNLOCK(cc);
1013 return (1);
1014 }
1015
1016 void
1017 callout_init(c, mpsafe)
1018 struct callout *c;
1019 int mpsafe;
1020 {
1021 bzero(c, sizeof *c);
1022 if (mpsafe) {
1023 c->c_lock = NULL;
1024 c->c_flags = CALLOUT_RETURNUNLOCKED;
1025 } else {
1026 c->c_lock = &Giant.lock_object;
1027 c->c_flags = 0;
1028 }
1029 c->c_cpu = timeout_cpu;
1030 }
1031
1032 void
1033 _callout_init_lock(c, lock, flags)
1034 struct callout *c;
1035 struct lock_object *lock;
1036 int flags;
1037 {
1038 bzero(c, sizeof *c);
1039 c->c_lock = lock;
1040 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK)) == 0,
1041 ("callout_init_lock: bad flags %d", flags));
1042 KASSERT(lock != NULL || (flags & CALLOUT_RETURNUNLOCKED) == 0,
1043 ("callout_init_lock: CALLOUT_RETURNUNLOCKED with no lock"));
1044 KASSERT(lock == NULL || !(LOCK_CLASS(lock)->lc_flags &
1045 (LC_SPINLOCK | LC_SLEEPABLE)), ("%s: invalid lock class",
1046 __func__));
1047 c->c_flags = flags & (CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK);
1048 c->c_cpu = timeout_cpu;
1049 }
1050
1051 #ifdef APM_FIXUP_CALLTODO
1052 /*
1053 * Adjust the kernel calltodo timeout list. This routine is used after
1054 * an APM resume to recalculate the calltodo timer list values with the
1055 * number of hz's we have been sleeping. The next hardclock() will detect
1056 * that there are fired timers and run softclock() to execute them.
1057 *
1058 * Please note, I have not done an exhaustive analysis of what code this
1059 * might break. I am motivated to have my select()'s and alarm()'s that
1060 * have expired during suspend firing upon resume so that the applications
1061 * which set the timer can do the maintanence the timer was for as close
1062 * as possible to the originally intended time. Testing this code for a
1063 * week showed that resuming from a suspend resulted in 22 to 25 timers
1064 * firing, which seemed independant on whether the suspend was 2 hours or
1065 * 2 days. Your milage may vary. - Ken Key <key@cs.utk.edu>
1066 */
1067 void
1068 adjust_timeout_calltodo(time_change)
1069 struct timeval *time_change;
1070 {
1071 register struct callout *p;
1072 unsigned long delta_ticks;
1073
1074 /*
1075 * How many ticks were we asleep?
1076 * (stolen from tvtohz()).
1077 */
1078
1079 /* Don't do anything */
1080 if (time_change->tv_sec < 0)
1081 return;
1082 else if (time_change->tv_sec <= LONG_MAX / 1000000)
1083 delta_ticks = (time_change->tv_sec * 1000000 +
1084 time_change->tv_usec + (tick - 1)) / tick + 1;
1085 else if (time_change->tv_sec <= LONG_MAX / hz)
1086 delta_ticks = time_change->tv_sec * hz +
1087 (time_change->tv_usec + (tick - 1)) / tick + 1;
1088 else
1089 delta_ticks = LONG_MAX;
1090
1091 if (delta_ticks > INT_MAX)
1092 delta_ticks = INT_MAX;
1093
1094 /*
1095 * Now rip through the timer calltodo list looking for timers
1096 * to expire.
1097 */
1098
1099 /* don't collide with softclock() */
1100 CC_LOCK(cc);
1101 for (p = calltodo.c_next; p != NULL; p = p->c_next) {
1102 p->c_time -= delta_ticks;
1103
1104 /* Break if the timer had more time on it than delta_ticks */
1105 if (p->c_time > 0)
1106 break;
1107
1108 /* take back the ticks the timer didn't use (p->c_time <= 0) */
1109 delta_ticks = -p->c_time;
1110 }
1111 CC_UNLOCK(cc);
1112
1113 return;
1114 }
1115 #endif /* APM_FIXUP_CALLTODO */
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