1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1982, 1986, 1991, 1993
5 * The Regents of the University of California. All rights reserved.
6 * (c) UNIX System Laboratories, Inc.
7 * All or some portions of this file are derived from material licensed
8 * to the University of California by American Telephone and Telegraph
9 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
10 * the permission of UNIX System Laboratories, Inc.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37 #include <sys/cdefs.h>
38 #include "opt_callout_profiling.h"
39 #include "opt_ddb.h"
40 #include "opt_rss.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/domainset.h>
47 #include <sys/file.h>
48 #include <sys/interrupt.h>
49 #include <sys/kernel.h>
50 #include <sys/ktr.h>
51 #include <sys/kthread.h>
52 #include <sys/lock.h>
53 #include <sys/malloc.h>
54 #include <sys/mutex.h>
55 #include <sys/proc.h>
56 #include <sys/random.h>
57 #include <sys/sched.h>
58 #include <sys/sdt.h>
59 #include <sys/sleepqueue.h>
60 #include <sys/sysctl.h>
61 #include <sys/smp.h>
62 #include <sys/unistd.h>
63
64 #ifdef DDB
65 #include <ddb/ddb.h>
66 #include <ddb/db_sym.h>
67 #include <machine/_inttypes.h>
68 #endif
69
70 #ifdef SMP
71 #include <machine/cpu.h>
72 #endif
73
74 DPCPU_DECLARE(sbintime_t, hardclocktime);
75
76 SDT_PROVIDER_DEFINE(callout_execute);
77 SDT_PROBE_DEFINE1(callout_execute, , , callout__start, "struct callout *");
78 SDT_PROBE_DEFINE1(callout_execute, , , callout__end, "struct callout *");
79
80 static void softclock_thread(void *arg);
81
82 #ifdef CALLOUT_PROFILING
83 static int avg_depth;
84 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0,
85 "Average number of items examined per softclock call. Units = 1/1000");
86 static int avg_gcalls;
87 SYSCTL_INT(_debug, OID_AUTO, to_avg_gcalls, CTLFLAG_RD, &avg_gcalls, 0,
88 "Average number of Giant callouts made per softclock call. Units = 1/1000");
89 static int avg_lockcalls;
90 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls, CTLFLAG_RD, &avg_lockcalls, 0,
91 "Average number of lock callouts made per softclock call. Units = 1/1000");
92 static int avg_mpcalls;
93 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls, CTLFLAG_RD, &avg_mpcalls, 0,
94 "Average number of MP callouts made per softclock call. Units = 1/1000");
95 static int avg_depth_dir;
96 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth_dir, CTLFLAG_RD, &avg_depth_dir, 0,
97 "Average number of direct callouts examined per callout_process call. "
98 "Units = 1/1000");
99 static int avg_lockcalls_dir;
100 SYSCTL_INT(_debug, OID_AUTO, to_avg_lockcalls_dir, CTLFLAG_RD,
101 &avg_lockcalls_dir, 0, "Average number of lock direct callouts made per "
102 "callout_process call. Units = 1/1000");
103 static int avg_mpcalls_dir;
104 SYSCTL_INT(_debug, OID_AUTO, to_avg_mpcalls_dir, CTLFLAG_RD, &avg_mpcalls_dir,
105 0, "Average number of MP direct callouts made per callout_process call. "
106 "Units = 1/1000");
107 #endif
108
109 static int ncallout;
110 SYSCTL_INT(_kern, OID_AUTO, ncallout, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &ncallout, 0,
111 "Number of entries in callwheel and size of timeout() preallocation");
112
113 #ifdef RSS
114 static int pin_default_swi = 1;
115 static int pin_pcpu_swi = 1;
116 #else
117 static int pin_default_swi = 0;
118 static int pin_pcpu_swi = 0;
119 #endif
120
121 SYSCTL_INT(_kern, OID_AUTO, pin_default_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_default_swi,
122 0, "Pin the default (non-per-cpu) swi (shared with PCPU 0 swi)");
123 SYSCTL_INT(_kern, OID_AUTO, pin_pcpu_swi, CTLFLAG_RDTUN | CTLFLAG_NOFETCH, &pin_pcpu_swi,
124 0, "Pin the per-CPU swis (except PCPU 0, which is also default)");
125
126 /*
127 * TODO:
128 * allocate more timeout table slots when table overflows.
129 */
130 static u_int __read_mostly callwheelsize;
131 static u_int __read_mostly callwheelmask;
132
133 /*
134 * The callout cpu exec entities represent informations necessary for
135 * describing the state of callouts currently running on the CPU and the ones
136 * necessary for migrating callouts to the new callout cpu. In particular,
137 * the first entry of the array cc_exec_entity holds informations for callout
138 * running in SWI thread context, while the second one holds informations
139 * for callout running directly from hardware interrupt context.
140 * The cached informations are very important for deferring migration when
141 * the migrating callout is already running.
142 */
143 struct cc_exec {
144 struct callout *cc_curr;
145 void *cc_last_func;
146 void *cc_last_arg;
147 #ifdef SMP
148 callout_func_t *ce_migration_func;
149 void *ce_migration_arg;
150 sbintime_t ce_migration_time;
151 sbintime_t ce_migration_prec;
152 int ce_migration_cpu;
153 #endif
154 bool cc_cancel;
155 bool cc_waiting;
156 };
157
158 /*
159 * There is one struct callout_cpu per cpu, holding all relevant
160 * state for the callout processing thread on the individual CPU.
161 */
162 struct callout_cpu {
163 struct mtx_padalign cc_lock;
164 struct cc_exec cc_exec_entity[2];
165 struct callout *cc_next;
166 struct callout_list *cc_callwheel;
167 struct callout_tailq cc_expireq;
168 sbintime_t cc_firstevent;
169 sbintime_t cc_lastscan;
170 struct thread *cc_thread;
171 u_int cc_bucket;
172 #ifdef KTR
173 char cc_ktr_event_name[20];
174 #endif
175 };
176
177 #define callout_migrating(c) ((c)->c_iflags & CALLOUT_DFRMIGRATION)
178
179 #define cc_exec_curr(cc, dir) cc->cc_exec_entity[dir].cc_curr
180 #define cc_exec_last_func(cc, dir) cc->cc_exec_entity[dir].cc_last_func
181 #define cc_exec_last_arg(cc, dir) cc->cc_exec_entity[dir].cc_last_arg
182 #define cc_exec_next(cc) cc->cc_next
183 #define cc_exec_cancel(cc, dir) cc->cc_exec_entity[dir].cc_cancel
184 #define cc_exec_waiting(cc, dir) cc->cc_exec_entity[dir].cc_waiting
185 #ifdef SMP
186 #define cc_migration_func(cc, dir) cc->cc_exec_entity[dir].ce_migration_func
187 #define cc_migration_arg(cc, dir) cc->cc_exec_entity[dir].ce_migration_arg
188 #define cc_migration_cpu(cc, dir) cc->cc_exec_entity[dir].ce_migration_cpu
189 #define cc_migration_time(cc, dir) cc->cc_exec_entity[dir].ce_migration_time
190 #define cc_migration_prec(cc, dir) cc->cc_exec_entity[dir].ce_migration_prec
191
192 DPCPU_DEFINE_STATIC(struct callout_cpu, cc_cpu);
193 #define CPUBLOCK MAXCPU
194 #define CC_CPU(cpu) DPCPU_ID_PTR(cpu, cc_cpu)
195 #define CC_SELF() CC_CPU(PCPU_GET(cpuid))
196 #else
197 static struct callout_cpu cc_cpu;
198 #define CC_CPU(cpu) (&cc_cpu)
199 #define CC_SELF() (&cc_cpu)
200 #endif
201 #define CC_LOCK(cc) mtx_lock_spin(&(cc)->cc_lock)
202 #define CC_UNLOCK(cc) mtx_unlock_spin(&(cc)->cc_lock)
203 #define CC_LOCK_ASSERT(cc) mtx_assert(&(cc)->cc_lock, MA_OWNED)
204
205 static int __read_mostly cc_default_cpu;
206
207 static void callout_cpu_init(struct callout_cpu *cc, int cpu);
208 static void softclock_call_cc(struct callout *c, struct callout_cpu *cc,
209 #ifdef CALLOUT_PROFILING
210 int *mpcalls, int *lockcalls, int *gcalls,
211 #endif
212 int direct);
213
214 static MALLOC_DEFINE(M_CALLOUT, "callout", "Callout datastructures");
215
216 /**
217 * Locked by cc_lock:
218 * cc_curr - If a callout is in progress, it is cc_curr.
219 * If cc_curr is non-NULL, threads waiting in
220 * callout_drain() will be woken up as soon as the
221 * relevant callout completes.
222 * cc_cancel - Changing to 1 with both callout_lock and cc_lock held
223 * guarantees that the current callout will not run.
224 * The softclock_call_cc() function sets this to 0 before it
225 * drops callout_lock to acquire c_lock, and it calls
226 * the handler only if curr_cancelled is still 0 after
227 * cc_lock is successfully acquired.
228 * cc_waiting - If a thread is waiting in callout_drain(), then
229 * callout_wait is nonzero. Set only when
230 * cc_curr is non-NULL.
231 */
232
233 /*
234 * Resets the execution entity tied to a specific callout cpu.
235 */
236 static void
cc_cce_cleanup(struct callout_cpu * cc,int direct)237 cc_cce_cleanup(struct callout_cpu *cc, int direct)
238 {
239
240 cc_exec_curr(cc, direct) = NULL;
241 cc_exec_cancel(cc, direct) = false;
242 cc_exec_waiting(cc, direct) = false;
243 #ifdef SMP
244 cc_migration_cpu(cc, direct) = CPUBLOCK;
245 cc_migration_time(cc, direct) = 0;
246 cc_migration_prec(cc, direct) = 0;
247 cc_migration_func(cc, direct) = NULL;
248 cc_migration_arg(cc, direct) = NULL;
249 #endif
250 }
251
252 /*
253 * Checks if migration is requested by a specific callout cpu.
254 */
255 static int
cc_cce_migrating(struct callout_cpu * cc,int direct)256 cc_cce_migrating(struct callout_cpu *cc, int direct)
257 {
258
259 #ifdef SMP
260 return (cc_migration_cpu(cc, direct) != CPUBLOCK);
261 #else
262 return (0);
263 #endif
264 }
265
266 /*
267 * Kernel low level callwheel initialization
268 * called on the BSP during kernel startup.
269 */
270 static void
callout_callwheel_init(void * dummy)271 callout_callwheel_init(void *dummy)
272 {
273 struct callout_cpu *cc;
274 int cpu;
275
276 /*
277 * Calculate the size of the callout wheel and the preallocated
278 * timeout() structures.
279 * XXX: Clip callout to result of previous function of maxusers
280 * maximum 384. This is still huge, but acceptable.
281 */
282 ncallout = imin(16 + maxproc + maxfiles, 18508);
283 TUNABLE_INT_FETCH("kern.ncallout", &ncallout);
284
285 /*
286 * Calculate callout wheel size, should be next power of two higher
287 * than 'ncallout'.
288 */
289 callwheelsize = 1 << fls(ncallout);
290 callwheelmask = callwheelsize - 1;
291
292 /*
293 * Fetch whether we're pinning the swi's or not.
294 */
295 TUNABLE_INT_FETCH("kern.pin_default_swi", &pin_default_swi);
296 TUNABLE_INT_FETCH("kern.pin_pcpu_swi", &pin_pcpu_swi);
297
298 /*
299 * Initialize callout wheels. The software interrupt threads
300 * are created later.
301 */
302 cc_default_cpu = PCPU_GET(cpuid);
303 CPU_FOREACH(cpu) {
304 cc = CC_CPU(cpu);
305 callout_cpu_init(cc, cpu);
306 }
307 }
308 SYSINIT(callwheel_init, SI_SUB_CPU, SI_ORDER_ANY, callout_callwheel_init, NULL);
309
310 /*
311 * Initialize the per-cpu callout structures.
312 */
313 static void
callout_cpu_init(struct callout_cpu * cc,int cpu)314 callout_cpu_init(struct callout_cpu *cc, int cpu)
315 {
316 int i;
317
318 mtx_init(&cc->cc_lock, "callout", NULL, MTX_SPIN);
319 cc->cc_callwheel = malloc_domainset(sizeof(struct callout_list) *
320 callwheelsize, M_CALLOUT,
321 DOMAINSET_PREF(pcpu_find(cpu)->pc_domain), M_WAITOK);
322 for (i = 0; i < callwheelsize; i++)
323 LIST_INIT(&cc->cc_callwheel[i]);
324 TAILQ_INIT(&cc->cc_expireq);
325 cc->cc_firstevent = SBT_MAX;
326 for (i = 0; i < 2; i++)
327 cc_cce_cleanup(cc, i);
328 #ifdef KTR
329 snprintf(cc->cc_ktr_event_name, sizeof(cc->cc_ktr_event_name),
330 "callwheel cpu %d", cpu);
331 #endif
332 }
333
334 #ifdef SMP
335 /*
336 * Switches the cpu tied to a specific callout.
337 * The function expects a locked incoming callout cpu and returns with
338 * locked outcoming callout cpu.
339 */
340 static struct callout_cpu *
callout_cpu_switch(struct callout * c,struct callout_cpu * cc,int new_cpu)341 callout_cpu_switch(struct callout *c, struct callout_cpu *cc, int new_cpu)
342 {
343 struct callout_cpu *new_cc;
344
345 MPASS(c != NULL && cc != NULL);
346 CC_LOCK_ASSERT(cc);
347
348 /*
349 * Avoid interrupts and preemption firing after the callout cpu
350 * is blocked in order to avoid deadlocks as the new thread
351 * may be willing to acquire the callout cpu lock.
352 */
353 c->c_cpu = CPUBLOCK;
354 spinlock_enter();
355 CC_UNLOCK(cc);
356 new_cc = CC_CPU(new_cpu);
357 CC_LOCK(new_cc);
358 spinlock_exit();
359 c->c_cpu = new_cpu;
360 return (new_cc);
361 }
362 #endif
363
364 /*
365 * Start softclock threads.
366 */
367 static void
start_softclock(void * dummy)368 start_softclock(void *dummy)
369 {
370 struct proc *p;
371 struct thread *td;
372 struct callout_cpu *cc;
373 int cpu, error;
374 bool pin_swi;
375
376 p = NULL;
377 CPU_FOREACH(cpu) {
378 cc = CC_CPU(cpu);
379 error = kproc_kthread_add(softclock_thread, cc, &p, &td,
380 RFSTOPPED, 0, "clock", "clock (%d)", cpu);
381 if (error != 0)
382 panic("failed to create softclock thread for cpu %d: %d",
383 cpu, error);
384 CC_LOCK(cc);
385 cc->cc_thread = td;
386 thread_lock(td);
387 sched_class(td, PRI_ITHD);
388 sched_ithread_prio(td, PI_SOFTCLOCK);
389 TD_SET_IWAIT(td);
390 thread_lock_set(td, (struct mtx *)&cc->cc_lock);
391 thread_unlock(td);
392 if (cpu == cc_default_cpu)
393 pin_swi = pin_default_swi;
394 else
395 pin_swi = pin_pcpu_swi;
396 if (pin_swi) {
397 error = cpuset_setithread(td->td_tid, cpu);
398 if (error != 0)
399 printf("%s: %s clock couldn't be pinned to cpu %d: %d\n",
400 __func__, cpu == cc_default_cpu ?
401 "default" : "per-cpu", cpu, error);
402 }
403 }
404 }
405 SYSINIT(start_softclock, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_softclock, NULL);
406
407 #define CC_HASH_SHIFT 8
408
409 static inline u_int
callout_hash(sbintime_t sbt)410 callout_hash(sbintime_t sbt)
411 {
412
413 return (sbt >> (32 - CC_HASH_SHIFT));
414 }
415
416 static inline u_int
callout_get_bucket(sbintime_t sbt)417 callout_get_bucket(sbintime_t sbt)
418 {
419
420 return (callout_hash(sbt) & callwheelmask);
421 }
422
423 void
callout_process(sbintime_t now)424 callout_process(sbintime_t now)
425 {
426 struct callout_entropy {
427 struct callout_cpu *cc;
428 struct thread *td;
429 sbintime_t now;
430 } entropy;
431 struct callout *c, *next;
432 struct callout_cpu *cc;
433 struct callout_list *sc;
434 struct thread *td;
435 sbintime_t first, last, lookahead, max, tmp_max;
436 u_int firstb, lastb, nowb;
437 #ifdef CALLOUT_PROFILING
438 int depth_dir = 0, mpcalls_dir = 0, lockcalls_dir = 0;
439 #endif
440
441 cc = CC_SELF();
442 mtx_lock_spin_flags(&cc->cc_lock, MTX_QUIET);
443
444 /* Compute the buckets of the last scan and present times. */
445 firstb = callout_hash(cc->cc_lastscan);
446 cc->cc_lastscan = now;
447 nowb = callout_hash(now);
448
449 /* Compute the last bucket and minimum time of the bucket after it. */
450 if (nowb == firstb)
451 lookahead = (SBT_1S / 16);
452 else if (nowb - firstb == 1)
453 lookahead = (SBT_1S / 8);
454 else
455 lookahead = SBT_1S;
456 first = last = now;
457 first += (lookahead / 2);
458 last += lookahead;
459 last &= (0xffffffffffffffffLLU << (32 - CC_HASH_SHIFT));
460 lastb = callout_hash(last) - 1;
461 max = last;
462
463 /*
464 * Check if we wrapped around the entire wheel from the last scan.
465 * In case, we need to scan entirely the wheel for pending callouts.
466 */
467 if (lastb - firstb >= callwheelsize) {
468 lastb = firstb + callwheelsize - 1;
469 if (nowb - firstb >= callwheelsize)
470 nowb = lastb;
471 }
472
473 /* Iterate callwheel from firstb to nowb and then up to lastb. */
474 do {
475 sc = &cc->cc_callwheel[firstb & callwheelmask];
476 LIST_FOREACH_SAFE(c, sc, c_links.le, next) {
477 /* Run the callout if present time within allowed. */
478 if (c->c_time <= now) {
479 /*
480 * Consumer told us the callout may be run
481 * directly from hardware interrupt context.
482 */
483 if (c->c_iflags & CALLOUT_DIRECT) {
484 #ifdef CALLOUT_PROFILING
485 ++depth_dir;
486 #endif
487 cc_exec_next(cc) = next;
488 cc->cc_bucket = firstb & callwheelmask;
489 LIST_REMOVE(c, c_links.le);
490 softclock_call_cc(c, cc,
491 #ifdef CALLOUT_PROFILING
492 &mpcalls_dir, &lockcalls_dir, NULL,
493 #endif
494 1);
495 next = cc_exec_next(cc);
496 cc_exec_next(cc) = NULL;
497 } else {
498 LIST_REMOVE(c, c_links.le);
499 TAILQ_INSERT_TAIL(&cc->cc_expireq,
500 c, c_links.tqe);
501 c->c_iflags |= CALLOUT_PROCESSED;
502 }
503 } else if (c->c_time >= max) {
504 /*
505 * Skip events in the distant future.
506 */
507 ;
508 } else if (c->c_time > last) {
509 /*
510 * Event minimal time is bigger than present
511 * maximal time, so it cannot be aggregated.
512 */
513 lastb = nowb;
514 } else {
515 /*
516 * Update first and last time, respecting this
517 * event.
518 */
519 if (c->c_time < first)
520 first = c->c_time;
521 tmp_max = c->c_time + c->c_precision;
522 if (tmp_max < last)
523 last = tmp_max;
524 }
525 }
526 /* Proceed with the next bucket. */
527 firstb++;
528 /*
529 * Stop if we looked after present time and found
530 * some event we can't execute at now.
531 * Stop if we looked far enough into the future.
532 */
533 } while (((int)(firstb - lastb)) <= 0);
534 cc->cc_firstevent = last;
535 cpu_new_callout(curcpu, last, first);
536
537 #ifdef CALLOUT_PROFILING
538 avg_depth_dir += (depth_dir * 1000 - avg_depth_dir) >> 8;
539 avg_mpcalls_dir += (mpcalls_dir * 1000 - avg_mpcalls_dir) >> 8;
540 avg_lockcalls_dir += (lockcalls_dir * 1000 - avg_lockcalls_dir) >> 8;
541 #endif
542 if (!TAILQ_EMPTY(&cc->cc_expireq)) {
543 entropy.cc = cc;
544 entropy.td = curthread;
545 entropy.now = now;
546 random_harvest_queue(&entropy, sizeof(entropy), RANDOM_CALLOUT);
547
548 td = cc->cc_thread;
549 if (TD_AWAITING_INTR(td)) {
550 thread_lock_block_wait(td);
551 THREAD_LOCK_ASSERT(td, MA_OWNED);
552 TD_CLR_IWAIT(td);
553 sched_wakeup(td, SRQ_INTR);
554 } else
555 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET);
556 } else
557 mtx_unlock_spin_flags(&cc->cc_lock, MTX_QUIET);
558 }
559
560 static struct callout_cpu *
callout_lock(struct callout * c)561 callout_lock(struct callout *c)
562 {
563 struct callout_cpu *cc;
564 int cpu;
565
566 for (;;) {
567 cpu = c->c_cpu;
568 #ifdef SMP
569 if (cpu == CPUBLOCK) {
570 while (c->c_cpu == CPUBLOCK)
571 cpu_spinwait();
572 continue;
573 }
574 #endif
575 cc = CC_CPU(cpu);
576 CC_LOCK(cc);
577 if (cpu == c->c_cpu)
578 break;
579 CC_UNLOCK(cc);
580 }
581 return (cc);
582 }
583
584 static void
callout_cc_add(struct callout * c,struct callout_cpu * cc,sbintime_t sbt,sbintime_t precision,void (* func)(void *),void * arg,int flags)585 callout_cc_add(struct callout *c, struct callout_cpu *cc,
586 sbintime_t sbt, sbintime_t precision, void (*func)(void *),
587 void *arg, int flags)
588 {
589 int bucket;
590
591 CC_LOCK_ASSERT(cc);
592 if (sbt < cc->cc_lastscan)
593 sbt = cc->cc_lastscan;
594 c->c_arg = arg;
595 c->c_iflags |= CALLOUT_PENDING;
596 c->c_iflags &= ~CALLOUT_PROCESSED;
597 c->c_flags |= CALLOUT_ACTIVE;
598 if (flags & C_DIRECT_EXEC)
599 c->c_iflags |= CALLOUT_DIRECT;
600 c->c_func = func;
601 c->c_time = sbt;
602 c->c_precision = precision;
603 bucket = callout_get_bucket(c->c_time);
604 CTR3(KTR_CALLOUT, "precision set for %p: %d.%08x",
605 c, (int)(c->c_precision >> 32),
606 (u_int)(c->c_precision & 0xffffffff));
607 LIST_INSERT_HEAD(&cc->cc_callwheel[bucket], c, c_links.le);
608 if (cc->cc_bucket == bucket)
609 cc_exec_next(cc) = c;
610
611 /*
612 * Inform the eventtimers(4) subsystem there's a new callout
613 * that has been inserted, but only if really required.
614 */
615 if (SBT_MAX - c->c_time < c->c_precision)
616 c->c_precision = SBT_MAX - c->c_time;
617 sbt = c->c_time + c->c_precision;
618 if (sbt < cc->cc_firstevent) {
619 cc->cc_firstevent = sbt;
620 cpu_new_callout(c->c_cpu, sbt, c->c_time);
621 }
622 }
623
624 static void
softclock_call_cc(struct callout * c,struct callout_cpu * cc,int * mpcalls,int * lockcalls,int * gcalls,int direct)625 softclock_call_cc(struct callout *c, struct callout_cpu *cc,
626 #ifdef CALLOUT_PROFILING
627 int *mpcalls, int *lockcalls, int *gcalls,
628 #endif
629 int direct)
630 {
631 struct rm_priotracker tracker;
632 callout_func_t *c_func;
633 void *c_arg;
634 struct lock_class *class;
635 struct lock_object *c_lock;
636 uintptr_t lock_status;
637 int c_iflags;
638 #ifdef SMP
639 struct callout_cpu *new_cc;
640 callout_func_t *new_func;
641 void *new_arg;
642 int flags, new_cpu;
643 sbintime_t new_prec, new_time;
644 #endif
645 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
646 sbintime_t sbt1, sbt2;
647 struct timespec ts2;
648 static sbintime_t maxdt = 2 * SBT_1MS; /* 2 msec */
649 static callout_func_t *lastfunc;
650 #endif
651
652 CC_LOCK_ASSERT(cc);
653 KASSERT((c->c_iflags & CALLOUT_PENDING) == CALLOUT_PENDING,
654 ("softclock_call_cc: pend %p %x", c, c->c_iflags));
655 KASSERT((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE,
656 ("softclock_call_cc: act %p %x", c, c->c_flags));
657 class = (c->c_lock != NULL) ? LOCK_CLASS(c->c_lock) : NULL;
658 lock_status = 0;
659 if (c->c_iflags & CALLOUT_SHAREDLOCK) {
660 if (class == &lock_class_rm)
661 lock_status = (uintptr_t)&tracker;
662 else
663 lock_status = 1;
664 }
665 c_lock = c->c_lock;
666 c_func = c->c_func;
667 c_arg = c->c_arg;
668 c_iflags = c->c_iflags;
669 c->c_iflags &= ~CALLOUT_PENDING;
670
671 cc_exec_curr(cc, direct) = c;
672 cc_exec_last_func(cc, direct) = c_func;
673 cc_exec_last_arg(cc, direct) = c_arg;
674 cc_exec_cancel(cc, direct) = false;
675 if (c_lock != NULL) {
676 if (c_iflags & CALLOUT_TRYLOCK) {
677 if (__predict_false(class->lc_trylock(c_lock,
678 lock_status) == 0)) {
679 cc_exec_curr(cc, direct) = NULL;
680 callout_cc_add(c, cc,
681 cc->cc_lastscan + c->c_precision / 2,
682 qmax(c->c_precision / 2, 1), c_func, c_arg,
683 (direct) ? C_DIRECT_EXEC : 0);
684 return;
685 }
686 CC_UNLOCK(cc);
687 } else {
688 CC_UNLOCK(cc);
689 class->lc_lock(c_lock, lock_status);
690 /*
691 * The callout may have been cancelled
692 * while we switched locks.
693 */
694 if (cc_exec_cancel(cc, direct)) {
695 class->lc_unlock(c_lock);
696 goto skip;
697 }
698 }
699 /* The callout cannot be stopped now. */
700 cc_exec_cancel(cc, direct) = true;
701 if (c_lock == &Giant.lock_object) {
702 #ifdef CALLOUT_PROFILING
703 (*gcalls)++;
704 #endif
705 CTR3(KTR_CALLOUT, "callout giant %p func %p arg %p",
706 c, c_func, c_arg);
707 } else {
708 #ifdef CALLOUT_PROFILING
709 (*lockcalls)++;
710 #endif
711 CTR3(KTR_CALLOUT, "callout lock %p func %p arg %p",
712 c, c_func, c_arg);
713 }
714 } else {
715 CC_UNLOCK(cc);
716 #ifdef CALLOUT_PROFILING
717 (*mpcalls)++;
718 #endif
719 CTR3(KTR_CALLOUT, "callout %p func %p arg %p",
720 c, c_func, c_arg);
721 }
722 KTR_STATE3(KTR_SCHED, "callout", cc->cc_ktr_event_name, "running",
723 "func:%p", c_func, "arg:%p", c_arg, "direct:%d", direct);
724 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
725 sbt1 = sbinuptime();
726 #endif
727 THREAD_NO_SLEEPING();
728 SDT_PROBE1(callout_execute, , , callout__start, c);
729 c_func(c_arg);
730 SDT_PROBE1(callout_execute, , , callout__end, c);
731 THREAD_SLEEPING_OK();
732 #if defined(DIAGNOSTIC) || defined(CALLOUT_PROFILING)
733 sbt2 = sbinuptime();
734 sbt2 -= sbt1;
735 if (sbt2 > maxdt) {
736 if (lastfunc != c_func || sbt2 > maxdt * 2) {
737 ts2 = sbttots(sbt2);
738 printf(
739 "Expensive callout(9) function: %p(%p) %jd.%09ld s\n",
740 c_func, c_arg, (intmax_t)ts2.tv_sec, ts2.tv_nsec);
741 }
742 maxdt = sbt2;
743 lastfunc = c_func;
744 }
745 #endif
746 KTR_STATE0(KTR_SCHED, "callout", cc->cc_ktr_event_name, "idle");
747 CTR1(KTR_CALLOUT, "callout %p finished", c);
748 if ((c_iflags & CALLOUT_RETURNUNLOCKED) == 0)
749 class->lc_unlock(c_lock);
750 skip:
751 CC_LOCK(cc);
752 KASSERT(cc_exec_curr(cc, direct) == c, ("mishandled cc_curr"));
753 cc_exec_curr(cc, direct) = NULL;
754 if (cc_exec_waiting(cc, direct)) {
755 /*
756 * There is someone waiting for the
757 * callout to complete.
758 * If the callout was scheduled for
759 * migration just cancel it.
760 */
761 if (cc_cce_migrating(cc, direct)) {
762 cc_cce_cleanup(cc, direct);
763
764 /*
765 * It should be assert here that the callout is not
766 * destroyed but that is not easy.
767 */
768 c->c_iflags &= ~CALLOUT_DFRMIGRATION;
769 }
770 cc_exec_waiting(cc, direct) = false;
771 CC_UNLOCK(cc);
772 wakeup(&cc_exec_waiting(cc, direct));
773 CC_LOCK(cc);
774 } else if (cc_cce_migrating(cc, direct)) {
775 #ifdef SMP
776 /*
777 * If the callout was scheduled for
778 * migration just perform it now.
779 */
780 new_cpu = cc_migration_cpu(cc, direct);
781 new_time = cc_migration_time(cc, direct);
782 new_prec = cc_migration_prec(cc, direct);
783 new_func = cc_migration_func(cc, direct);
784 new_arg = cc_migration_arg(cc, direct);
785 cc_cce_cleanup(cc, direct);
786
787 /*
788 * It should be assert here that the callout is not destroyed
789 * but that is not easy.
790 *
791 * As first thing, handle deferred callout stops.
792 */
793 if (!callout_migrating(c)) {
794 CTR3(KTR_CALLOUT,
795 "deferred cancelled %p func %p arg %p",
796 c, new_func, new_arg);
797 return;
798 }
799 c->c_iflags &= ~CALLOUT_DFRMIGRATION;
800
801 new_cc = callout_cpu_switch(c, cc, new_cpu);
802 flags = (direct) ? C_DIRECT_EXEC : 0;
803 callout_cc_add(c, new_cc, new_time, new_prec, new_func,
804 new_arg, flags);
805 CC_UNLOCK(new_cc);
806 CC_LOCK(cc);
807 #else
808 panic("migration should not happen");
809 #endif
810 }
811 }
812
813 /*
814 * The callout mechanism is based on the work of Adam M. Costello and
815 * George Varghese, published in a technical report entitled "Redesigning
816 * the BSD Callout and Timer Facilities" and modified slightly for inclusion
817 * in FreeBSD by Justin T. Gibbs. The original work on the data structures
818 * used in this implementation was published by G. Varghese and T. Lauck in
819 * the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
820 * the Efficient Implementation of a Timer Facility" in the Proceedings of
821 * the 11th ACM Annual Symposium on Operating Systems Principles,
822 * Austin, Texas Nov 1987.
823 */
824
825 /*
826 * Software (low priority) clock interrupt thread handler.
827 * Run periodic events from timeout queue.
828 */
829 static void
softclock_thread(void * arg)830 softclock_thread(void *arg)
831 {
832 struct thread *td = curthread;
833 struct callout_cpu *cc;
834 struct callout *c;
835 #ifdef CALLOUT_PROFILING
836 int depth, gcalls, lockcalls, mpcalls;
837 #endif
838
839 cc = (struct callout_cpu *)arg;
840 CC_LOCK(cc);
841 for (;;) {
842 while (TAILQ_EMPTY(&cc->cc_expireq)) {
843 /*
844 * Use CC_LOCK(cc) as the thread_lock while
845 * idle.
846 */
847 thread_lock(td);
848 thread_lock_set(td, (struct mtx *)&cc->cc_lock);
849 TD_SET_IWAIT(td);
850 mi_switch(SW_VOL | SWT_IWAIT);
851
852 /* mi_switch() drops thread_lock(). */
853 CC_LOCK(cc);
854 }
855
856 #ifdef CALLOUT_PROFILING
857 depth = gcalls = lockcalls = mpcalls = 0;
858 #endif
859 while ((c = TAILQ_FIRST(&cc->cc_expireq)) != NULL) {
860 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
861 softclock_call_cc(c, cc,
862 #ifdef CALLOUT_PROFILING
863 &mpcalls, &lockcalls, &gcalls,
864 #endif
865 0);
866 #ifdef CALLOUT_PROFILING
867 ++depth;
868 #endif
869 }
870 #ifdef CALLOUT_PROFILING
871 avg_depth += (depth * 1000 - avg_depth) >> 8;
872 avg_mpcalls += (mpcalls * 1000 - avg_mpcalls) >> 8;
873 avg_lockcalls += (lockcalls * 1000 - avg_lockcalls) >> 8;
874 avg_gcalls += (gcalls * 1000 - avg_gcalls) >> 8;
875 #endif
876 }
877 }
878
879 void
callout_when(sbintime_t sbt,sbintime_t precision,int flags,sbintime_t * res,sbintime_t * prec_res)880 callout_when(sbintime_t sbt, sbintime_t precision, int flags,
881 sbintime_t *res, sbintime_t *prec_res)
882 {
883 sbintime_t to_sbt, to_pr;
884
885 if ((flags & (C_ABSOLUTE | C_PRECALC)) != 0) {
886 *res = sbt;
887 *prec_res = precision;
888 return;
889 }
890 if ((flags & C_HARDCLOCK) != 0 && sbt < tick_sbt)
891 sbt = tick_sbt;
892 if ((flags & C_HARDCLOCK) != 0 || sbt >= sbt_tickthreshold) {
893 /*
894 * Obtain the time of the last hardclock() call on
895 * this CPU directly from the kern_clocksource.c.
896 * This value is per-CPU, but it is equal for all
897 * active ones.
898 */
899 #ifdef __LP64__
900 to_sbt = DPCPU_GET(hardclocktime);
901 #else
902 spinlock_enter();
903 to_sbt = DPCPU_GET(hardclocktime);
904 spinlock_exit();
905 #endif
906 if (cold && to_sbt == 0)
907 to_sbt = sbinuptime();
908 if ((flags & C_HARDCLOCK) == 0)
909 to_sbt += tick_sbt;
910 } else
911 to_sbt = sbinuptime();
912 if (SBT_MAX - to_sbt < sbt)
913 to_sbt = SBT_MAX;
914 else
915 to_sbt += sbt;
916 *res = to_sbt;
917 to_pr = ((C_PRELGET(flags) < 0) ? sbt >> tc_precexp :
918 sbt >> C_PRELGET(flags));
919 *prec_res = to_pr > precision ? to_pr : precision;
920 }
921
922 /*
923 * New interface; clients allocate their own callout structures.
924 *
925 * callout_reset() - establish or change a timeout
926 * callout_stop() - disestablish a timeout
927 * callout_init() - initialize a callout structure so that it can
928 * safely be passed to callout_reset() and callout_stop()
929 *
930 * <sys/callout.h> defines three convenience macros:
931 *
932 * callout_active() - returns truth if callout has not been stopped,
933 * drained, or deactivated since the last time the callout was
934 * reset.
935 * callout_pending() - returns truth if callout is still waiting for timeout
936 * callout_deactivate() - marks the callout as having been serviced
937 */
938 int
callout_reset_sbt_on(struct callout * c,sbintime_t sbt,sbintime_t prec,callout_func_t * ftn,void * arg,int cpu,int flags)939 callout_reset_sbt_on(struct callout *c, sbintime_t sbt, sbintime_t prec,
940 callout_func_t *ftn, void *arg, int cpu, int flags)
941 {
942 sbintime_t to_sbt, precision;
943 struct callout_cpu *cc;
944 int cancelled, direct;
945
946 cancelled = 0;
947 callout_when(sbt, prec, flags, &to_sbt, &precision);
948
949 /*
950 * This flag used to be added by callout_cc_add, but the
951 * first time you call this we could end up with the
952 * wrong direct flag if we don't do it before we add.
953 */
954 if (flags & C_DIRECT_EXEC) {
955 direct = 1;
956 } else {
957 direct = 0;
958 }
959 KASSERT(!direct || c->c_lock == NULL ||
960 (LOCK_CLASS(c->c_lock)->lc_flags & LC_SPINLOCK),
961 ("%s: direct callout %p has non-spin lock", __func__, c));
962
963 cc = callout_lock(c);
964 if (cpu == -1)
965 cpu = c->c_cpu;
966 KASSERT(cpu >= 0 && cpu <= mp_maxid && !CPU_ABSENT(cpu),
967 ("%s: invalid cpu %d", __func__, cpu));
968
969 if (cc_exec_curr(cc, direct) == c) {
970 /*
971 * We're being asked to reschedule a callout which is
972 * currently in progress. If there is a lock then we
973 * can cancel the callout if it has not really started.
974 */
975 if (c->c_lock != NULL && !cc_exec_cancel(cc, direct))
976 cancelled = cc_exec_cancel(cc, direct) = true;
977 if (cc_exec_waiting(cc, direct)) {
978 /*
979 * Someone has called callout_drain to kill this
980 * callout. Don't reschedule.
981 */
982 CTR4(KTR_CALLOUT, "%s %p func %p arg %p",
983 cancelled ? "cancelled" : "failed to cancel",
984 c, c->c_func, c->c_arg);
985 CC_UNLOCK(cc);
986 return (cancelled);
987 }
988 #ifdef SMP
989 if (callout_migrating(c)) {
990 /*
991 * This only occurs when a second callout_reset_sbt_on
992 * is made after a previous one moved it into
993 * deferred migration (below). Note we do *not* change
994 * the prev_cpu even though the previous target may
995 * be different.
996 */
997 cc_migration_cpu(cc, direct) = cpu;
998 cc_migration_time(cc, direct) = to_sbt;
999 cc_migration_prec(cc, direct) = precision;
1000 cc_migration_func(cc, direct) = ftn;
1001 cc_migration_arg(cc, direct) = arg;
1002 cancelled = 1;
1003 CC_UNLOCK(cc);
1004 return (cancelled);
1005 }
1006 #endif
1007 }
1008 if (c->c_iflags & CALLOUT_PENDING) {
1009 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) {
1010 if (cc_exec_next(cc) == c)
1011 cc_exec_next(cc) = LIST_NEXT(c, c_links.le);
1012 LIST_REMOVE(c, c_links.le);
1013 } else {
1014 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
1015 }
1016 cancelled = 1;
1017 c->c_iflags &= ~ CALLOUT_PENDING;
1018 c->c_flags &= ~ CALLOUT_ACTIVE;
1019 }
1020
1021 #ifdef SMP
1022 /*
1023 * If the callout must migrate try to perform it immediately.
1024 * If the callout is currently running, just defer the migration
1025 * to a more appropriate moment.
1026 */
1027 if (c->c_cpu != cpu) {
1028 if (cc_exec_curr(cc, direct) == c) {
1029 /*
1030 * Pending will have been removed since we are
1031 * actually executing the callout on another
1032 * CPU. That callout should be waiting on the
1033 * lock the caller holds. If we set both
1034 * active/and/pending after we return and the
1035 * lock on the executing callout proceeds, it
1036 * will then see pending is true and return.
1037 * At the return from the actual callout execution
1038 * the migration will occur in softclock_call_cc
1039 * and this new callout will be placed on the
1040 * new CPU via a call to callout_cpu_switch() which
1041 * will get the lock on the right CPU followed
1042 * by a call callout_cc_add() which will add it there.
1043 * (see above in softclock_call_cc()).
1044 */
1045 cc_migration_cpu(cc, direct) = cpu;
1046 cc_migration_time(cc, direct) = to_sbt;
1047 cc_migration_prec(cc, direct) = precision;
1048 cc_migration_func(cc, direct) = ftn;
1049 cc_migration_arg(cc, direct) = arg;
1050 c->c_iflags |= (CALLOUT_DFRMIGRATION | CALLOUT_PENDING);
1051 c->c_flags |= CALLOUT_ACTIVE;
1052 CTR6(KTR_CALLOUT,
1053 "migration of %p func %p arg %p in %d.%08x to %u deferred",
1054 c, c->c_func, c->c_arg, (int)(to_sbt >> 32),
1055 (u_int)(to_sbt & 0xffffffff), cpu);
1056 CC_UNLOCK(cc);
1057 return (cancelled);
1058 }
1059 cc = callout_cpu_switch(c, cc, cpu);
1060 }
1061 #endif
1062
1063 callout_cc_add(c, cc, to_sbt, precision, ftn, arg, flags);
1064 CTR6(KTR_CALLOUT, "%sscheduled %p func %p arg %p in %d.%08x",
1065 cancelled ? "re" : "", c, c->c_func, c->c_arg, (int)(to_sbt >> 32),
1066 (u_int)(to_sbt & 0xffffffff));
1067 CC_UNLOCK(cc);
1068
1069 return (cancelled);
1070 }
1071
1072 /*
1073 * Common idioms that can be optimized in the future.
1074 */
1075 int
callout_schedule_on(struct callout * c,int to_ticks,int cpu)1076 callout_schedule_on(struct callout *c, int to_ticks, int cpu)
1077 {
1078 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, cpu);
1079 }
1080
1081 int
callout_schedule(struct callout * c,int to_ticks)1082 callout_schedule(struct callout *c, int to_ticks)
1083 {
1084 return callout_reset_on(c, to_ticks, c->c_func, c->c_arg, c->c_cpu);
1085 }
1086
1087 int
_callout_stop_safe(struct callout * c,int flags)1088 _callout_stop_safe(struct callout *c, int flags)
1089 {
1090 struct callout_cpu *cc, *old_cc;
1091 struct lock_class *class;
1092 int direct, sq_locked, use_lock;
1093 int cancelled, not_on_a_list;
1094
1095 if ((flags & CS_DRAIN) != 0)
1096 WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, c->c_lock,
1097 "calling %s", __func__);
1098
1099 /*
1100 * Some old subsystems don't hold Giant while running a callout_stop(),
1101 * so just discard this check for the moment.
1102 */
1103 if ((flags & CS_DRAIN) == 0 && c->c_lock != NULL) {
1104 if (c->c_lock == &Giant.lock_object)
1105 use_lock = mtx_owned(&Giant);
1106 else {
1107 use_lock = 1;
1108 class = LOCK_CLASS(c->c_lock);
1109 class->lc_assert(c->c_lock, LA_XLOCKED);
1110 }
1111 } else
1112 use_lock = 0;
1113 if (c->c_iflags & CALLOUT_DIRECT) {
1114 direct = 1;
1115 } else {
1116 direct = 0;
1117 }
1118 sq_locked = 0;
1119 old_cc = NULL;
1120 again:
1121 cc = callout_lock(c);
1122
1123 if ((c->c_iflags & (CALLOUT_DFRMIGRATION | CALLOUT_PENDING)) ==
1124 (CALLOUT_DFRMIGRATION | CALLOUT_PENDING) &&
1125 ((c->c_flags & CALLOUT_ACTIVE) == CALLOUT_ACTIVE)) {
1126 /*
1127 * Special case where this slipped in while we
1128 * were migrating *as* the callout is about to
1129 * execute. The caller probably holds the lock
1130 * the callout wants.
1131 *
1132 * Get rid of the migration first. Then set
1133 * the flag that tells this code *not* to
1134 * try to remove it from any lists (its not
1135 * on one yet). When the callout wheel runs,
1136 * it will ignore this callout.
1137 */
1138 c->c_iflags &= ~CALLOUT_PENDING;
1139 c->c_flags &= ~CALLOUT_ACTIVE;
1140 not_on_a_list = 1;
1141 } else {
1142 not_on_a_list = 0;
1143 }
1144
1145 /*
1146 * If the callout was migrating while the callout cpu lock was
1147 * dropped, just drop the sleepqueue lock and check the states
1148 * again.
1149 */
1150 if (sq_locked != 0 && cc != old_cc) {
1151 #ifdef SMP
1152 CC_UNLOCK(cc);
1153 sleepq_release(&cc_exec_waiting(old_cc, direct));
1154 sq_locked = 0;
1155 old_cc = NULL;
1156 goto again;
1157 #else
1158 panic("migration should not happen");
1159 #endif
1160 }
1161
1162 /*
1163 * If the callout is running, try to stop it or drain it.
1164 */
1165 if (cc_exec_curr(cc, direct) == c) {
1166 /*
1167 * Succeed we to stop it or not, we must clear the
1168 * active flag - this is what API users expect. If we're
1169 * draining and the callout is currently executing, first wait
1170 * until it finishes.
1171 */
1172 if ((flags & CS_DRAIN) == 0)
1173 c->c_flags &= ~CALLOUT_ACTIVE;
1174
1175 if ((flags & CS_DRAIN) != 0) {
1176 /*
1177 * The current callout is running (or just
1178 * about to run) and blocking is allowed, so
1179 * just wait for the current invocation to
1180 * finish.
1181 */
1182 if (cc_exec_curr(cc, direct) == c) {
1183 /*
1184 * Use direct calls to sleepqueue interface
1185 * instead of cv/msleep in order to avoid
1186 * a LOR between cc_lock and sleepqueue
1187 * chain spinlocks. This piece of code
1188 * emulates a msleep_spin() call actually.
1189 *
1190 * If we already have the sleepqueue chain
1191 * locked, then we can safely block. If we
1192 * don't already have it locked, however,
1193 * we have to drop the cc_lock to lock
1194 * it. This opens several races, so we
1195 * restart at the beginning once we have
1196 * both locks. If nothing has changed, then
1197 * we will end up back here with sq_locked
1198 * set.
1199 */
1200 if (!sq_locked) {
1201 CC_UNLOCK(cc);
1202 sleepq_lock(
1203 &cc_exec_waiting(cc, direct));
1204 sq_locked = 1;
1205 old_cc = cc;
1206 goto again;
1207 }
1208
1209 /*
1210 * Migration could be cancelled here, but
1211 * as long as it is still not sure when it
1212 * will be packed up, just let softclock()
1213 * take care of it.
1214 */
1215 cc_exec_waiting(cc, direct) = true;
1216 DROP_GIANT();
1217 CC_UNLOCK(cc);
1218 sleepq_add(
1219 &cc_exec_waiting(cc, direct),
1220 &cc->cc_lock.lock_object, "codrain",
1221 SLEEPQ_SLEEP, 0);
1222 sleepq_wait(
1223 &cc_exec_waiting(cc, direct),
1224 0);
1225 sq_locked = 0;
1226 old_cc = NULL;
1227
1228 /* Reacquire locks previously released. */
1229 PICKUP_GIANT();
1230 goto again;
1231 }
1232 c->c_flags &= ~CALLOUT_ACTIVE;
1233 } else if (use_lock && !cc_exec_cancel(cc, direct)) {
1234
1235 /*
1236 * The current callout is waiting for its
1237 * lock which we hold. Cancel the callout
1238 * and return. After our caller drops the
1239 * lock, the callout will be skipped in
1240 * softclock(). This *only* works with a
1241 * callout_stop() *not* with callout_drain().
1242 */
1243 cc_exec_cancel(cc, direct) = true;
1244 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
1245 c, c->c_func, c->c_arg);
1246 KASSERT(!cc_cce_migrating(cc, direct),
1247 ("callout wrongly scheduled for migration"));
1248 if (callout_migrating(c)) {
1249 c->c_iflags &= ~CALLOUT_DFRMIGRATION;
1250 #ifdef SMP
1251 cc_migration_cpu(cc, direct) = CPUBLOCK;
1252 cc_migration_time(cc, direct) = 0;
1253 cc_migration_prec(cc, direct) = 0;
1254 cc_migration_func(cc, direct) = NULL;
1255 cc_migration_arg(cc, direct) = NULL;
1256 #endif
1257 }
1258 CC_UNLOCK(cc);
1259 KASSERT(!sq_locked, ("sleepqueue chain locked"));
1260 return (1);
1261 } else if (callout_migrating(c)) {
1262 /*
1263 * The callout is currently being serviced
1264 * and the "next" callout is scheduled at
1265 * its completion with a migration. We remove
1266 * the migration flag so it *won't* get rescheduled,
1267 * but we can't stop the one thats running so
1268 * we return 0.
1269 */
1270 c->c_iflags &= ~CALLOUT_DFRMIGRATION;
1271 #ifdef SMP
1272 /*
1273 * We can't call cc_cce_cleanup here since
1274 * if we do it will remove .ce_curr and
1275 * its still running. This will prevent a
1276 * reschedule of the callout when the
1277 * execution completes.
1278 */
1279 cc_migration_cpu(cc, direct) = CPUBLOCK;
1280 cc_migration_time(cc, direct) = 0;
1281 cc_migration_prec(cc, direct) = 0;
1282 cc_migration_func(cc, direct) = NULL;
1283 cc_migration_arg(cc, direct) = NULL;
1284 #endif
1285 CTR3(KTR_CALLOUT, "postponing stop %p func %p arg %p",
1286 c, c->c_func, c->c_arg);
1287 CC_UNLOCK(cc);
1288 return (0);
1289 } else {
1290 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
1291 c, c->c_func, c->c_arg);
1292 }
1293 KASSERT(!sq_locked, ("sleepqueue chain still locked"));
1294 cancelled = 0;
1295 } else
1296 cancelled = 1;
1297
1298 if (sq_locked)
1299 sleepq_release(&cc_exec_waiting(cc, direct));
1300
1301 if ((c->c_iflags & CALLOUT_PENDING) == 0) {
1302 CTR3(KTR_CALLOUT, "failed to stop %p func %p arg %p",
1303 c, c->c_func, c->c_arg);
1304 /*
1305 * For not scheduled and not executing callout return
1306 * negative value.
1307 */
1308 if (cc_exec_curr(cc, direct) != c)
1309 cancelled = -1;
1310 CC_UNLOCK(cc);
1311 return (cancelled);
1312 }
1313
1314 c->c_iflags &= ~CALLOUT_PENDING;
1315 c->c_flags &= ~CALLOUT_ACTIVE;
1316
1317 CTR3(KTR_CALLOUT, "cancelled %p func %p arg %p",
1318 c, c->c_func, c->c_arg);
1319 if (not_on_a_list == 0) {
1320 if ((c->c_iflags & CALLOUT_PROCESSED) == 0) {
1321 if (cc_exec_next(cc) == c)
1322 cc_exec_next(cc) = LIST_NEXT(c, c_links.le);
1323 LIST_REMOVE(c, c_links.le);
1324 } else {
1325 TAILQ_REMOVE(&cc->cc_expireq, c, c_links.tqe);
1326 }
1327 }
1328 CC_UNLOCK(cc);
1329 return (cancelled);
1330 }
1331
1332 void
callout_init(struct callout * c,int mpsafe)1333 callout_init(struct callout *c, int mpsafe)
1334 {
1335 bzero(c, sizeof *c);
1336 if (mpsafe) {
1337 c->c_lock = NULL;
1338 c->c_iflags = CALLOUT_RETURNUNLOCKED;
1339 } else {
1340 c->c_lock = &Giant.lock_object;
1341 c->c_iflags = 0;
1342 }
1343 c->c_cpu = cc_default_cpu;
1344 }
1345
1346 void
_callout_init_lock(struct callout * c,struct lock_object * lock,int flags)1347 _callout_init_lock(struct callout *c, struct lock_object *lock, int flags)
1348 {
1349 KASSERT(lock != NULL, ("%s: no lock", __func__));
1350 KASSERT((flags & ~(CALLOUT_RETURNUNLOCKED | CALLOUT_SHAREDLOCK |
1351 CALLOUT_TRYLOCK)) == 0,
1352 ("%s: bad flags %d", __func__, flags));
1353 KASSERT(!(LOCK_CLASS(lock)->lc_flags & LC_SLEEPABLE),
1354 ("%s: callout %p has sleepable lock", __func__, c));
1355 KASSERT(!(flags & CALLOUT_TRYLOCK) ||
1356 (LOCK_CLASS(lock)->lc_trylock != NULL),
1357 ("%s: CALLOUT_TRYLOCK requested for %s",
1358 __func__, LOCK_CLASS(lock)->lc_name));
1359
1360 *c = (struct callout ){
1361 .c_lock = lock,
1362 .c_iflags = flags,
1363 .c_cpu = cc_default_cpu,
1364 };
1365 }
1366
1367 static int
flssbt(sbintime_t sbt)1368 flssbt(sbintime_t sbt)
1369 {
1370
1371 sbt += (uint64_t)sbt >> 1;
1372 if (sizeof(long) >= sizeof(sbintime_t))
1373 return (flsl(sbt));
1374 if (sbt >= SBT_1S)
1375 return (flsl(((uint64_t)sbt) >> 32) + 32);
1376 return (flsl(sbt));
1377 }
1378
1379 /*
1380 * Dump immediate statistic snapshot of the scheduled callouts.
1381 */
1382 static int
sysctl_kern_callout_stat(SYSCTL_HANDLER_ARGS)1383 sysctl_kern_callout_stat(SYSCTL_HANDLER_ARGS)
1384 {
1385 struct callout *tmp;
1386 struct callout_cpu *cc;
1387 struct callout_list *sc;
1388 sbintime_t maxpr, maxt, medpr, medt, now, spr, st, t;
1389 int ct[64], cpr[64], ccpbk[32];
1390 int error, val, i, count, tcum, pcum, maxc, c, medc;
1391 int cpu;
1392
1393 val = 0;
1394 error = sysctl_handle_int(oidp, &val, 0, req);
1395 if (error != 0 || req->newptr == NULL)
1396 return (error);
1397 count = maxc = 0;
1398 st = spr = maxt = maxpr = 0;
1399 bzero(ccpbk, sizeof(ccpbk));
1400 bzero(ct, sizeof(ct));
1401 bzero(cpr, sizeof(cpr));
1402 now = sbinuptime();
1403 CPU_FOREACH(cpu) {
1404 cc = CC_CPU(cpu);
1405 CC_LOCK(cc);
1406 for (i = 0; i < callwheelsize; i++) {
1407 sc = &cc->cc_callwheel[i];
1408 c = 0;
1409 LIST_FOREACH(tmp, sc, c_links.le) {
1410 c++;
1411 t = tmp->c_time - now;
1412 if (t < 0)
1413 t = 0;
1414 st += t / SBT_1US;
1415 spr += tmp->c_precision / SBT_1US;
1416 if (t > maxt)
1417 maxt = t;
1418 if (tmp->c_precision > maxpr)
1419 maxpr = tmp->c_precision;
1420 ct[flssbt(t)]++;
1421 cpr[flssbt(tmp->c_precision)]++;
1422 }
1423 if (c > maxc)
1424 maxc = c;
1425 ccpbk[fls(c + c / 2)]++;
1426 count += c;
1427 }
1428 CC_UNLOCK(cc);
1429 }
1430
1431 for (i = 0, tcum = 0; i < 64 && tcum < count / 2; i++)
1432 tcum += ct[i];
1433 medt = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0;
1434 for (i = 0, pcum = 0; i < 64 && pcum < count / 2; i++)
1435 pcum += cpr[i];
1436 medpr = (i >= 2) ? (((sbintime_t)1) << (i - 2)) : 0;
1437 for (i = 0, c = 0; i < 32 && c < count / 2; i++)
1438 c += ccpbk[i];
1439 medc = (i >= 2) ? (1 << (i - 2)) : 0;
1440
1441 printf("Scheduled callouts statistic snapshot:\n");
1442 printf(" Callouts: %6d Buckets: %6d*%-3d Bucket size: 0.%06ds\n",
1443 count, callwheelsize, mp_ncpus, 1000000 >> CC_HASH_SHIFT);
1444 printf(" C/Bk: med %5d avg %6d.%06jd max %6d\n",
1445 medc,
1446 count / callwheelsize / mp_ncpus,
1447 (uint64_t)count * 1000000 / callwheelsize / mp_ncpus % 1000000,
1448 maxc);
1449 printf(" Time: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n",
1450 medt / SBT_1S, (medt & 0xffffffff) * 1000000 >> 32,
1451 (st / count) / 1000000, (st / count) % 1000000,
1452 maxt / SBT_1S, (maxt & 0xffffffff) * 1000000 >> 32);
1453 printf(" Prec: med %5jd.%06jds avg %6jd.%06jds max %6jd.%06jds\n",
1454 medpr / SBT_1S, (medpr & 0xffffffff) * 1000000 >> 32,
1455 (spr / count) / 1000000, (spr / count) % 1000000,
1456 maxpr / SBT_1S, (maxpr & 0xffffffff) * 1000000 >> 32);
1457 printf(" Distribution: \tbuckets\t time\t tcum\t"
1458 " prec\t pcum\n");
1459 for (i = 0, tcum = pcum = 0; i < 64; i++) {
1460 if (ct[i] == 0 && cpr[i] == 0)
1461 continue;
1462 t = (i != 0) ? (((sbintime_t)1) << (i - 1)) : 0;
1463 tcum += ct[i];
1464 pcum += cpr[i];
1465 printf(" %10jd.%06jds\t 2**%d\t%7d\t%7d\t%7d\t%7d\n",
1466 t / SBT_1S, (t & 0xffffffff) * 1000000 >> 32,
1467 i - 1 - (32 - CC_HASH_SHIFT),
1468 ct[i], tcum, cpr[i], pcum);
1469 }
1470 return (error);
1471 }
1472 SYSCTL_PROC(_kern, OID_AUTO, callout_stat,
1473 CTLTYPE_INT | CTLFLAG_RW | CTLFLAG_MPSAFE,
1474 0, 0, sysctl_kern_callout_stat, "I",
1475 "Dump immediate statistic snapshot of the scheduled callouts");
1476
1477 #ifdef DDB
1478 static void
_show_callout(struct callout * c)1479 _show_callout(struct callout *c)
1480 {
1481
1482 db_printf("callout %p\n", c);
1483 #define C_DB_PRINTF(f, e) db_printf(" %s = " f "\n", #e, c->e);
1484 db_printf(" &c_links = %p\n", &(c->c_links));
1485 C_DB_PRINTF("%" PRId64, c_time);
1486 C_DB_PRINTF("%" PRId64, c_precision);
1487 C_DB_PRINTF("%p", c_arg);
1488 C_DB_PRINTF("%p", c_func);
1489 C_DB_PRINTF("%p", c_lock);
1490 C_DB_PRINTF("%#x", c_flags);
1491 C_DB_PRINTF("%#x", c_iflags);
1492 C_DB_PRINTF("%d", c_cpu);
1493 #undef C_DB_PRINTF
1494 }
1495
DB_SHOW_COMMAND(callout,db_show_callout)1496 DB_SHOW_COMMAND(callout, db_show_callout)
1497 {
1498
1499 if (!have_addr) {
1500 db_printf("usage: show callout <struct callout *>\n");
1501 return;
1502 }
1503
1504 _show_callout((struct callout *)addr);
1505 }
1506
1507 static void
_show_last_callout(int cpu,int direct,const char * dirstr)1508 _show_last_callout(int cpu, int direct, const char *dirstr)
1509 {
1510 struct callout_cpu *cc;
1511 void *func, *arg;
1512
1513 cc = CC_CPU(cpu);
1514 func = cc_exec_last_func(cc, direct);
1515 arg = cc_exec_last_arg(cc, direct);
1516 db_printf("cpu %d last%s callout function: %p ", cpu, dirstr, func);
1517 db_printsym((db_expr_t)func, DB_STGY_ANY);
1518 db_printf("\ncpu %d last%s callout argument: %p\n", cpu, dirstr, arg);
1519 }
1520
DB_SHOW_COMMAND_FLAGS(callout_last,db_show_callout_last,DB_CMD_MEMSAFE)1521 DB_SHOW_COMMAND_FLAGS(callout_last, db_show_callout_last, DB_CMD_MEMSAFE)
1522 {
1523 int cpu, last;
1524
1525 if (have_addr) {
1526 if (addr < 0 || addr > mp_maxid || CPU_ABSENT(addr)) {
1527 db_printf("no such cpu: %d\n", (int)addr);
1528 return;
1529 }
1530 cpu = last = addr;
1531 } else {
1532 cpu = 0;
1533 last = mp_maxid;
1534 }
1535
1536 while (cpu <= last) {
1537 if (!CPU_ABSENT(cpu)) {
1538 _show_last_callout(cpu, 0, "");
1539 _show_last_callout(cpu, 1, " direct");
1540 }
1541 cpu++;
1542 }
1543 }
1544 #endif /* DDB */
1545