1 /*-
2 * Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. Berkeley Software Design Inc's name may not be used to endorse or
13 * promote products derived from this software without specific prior
14 * written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 *
28 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $
29 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $
30 */
31
32 /*
33 * Machine independent bits of mutex implementation.
34 */
35
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38
39 #include "opt_adaptive_mutexes.h"
40 #include "opt_ddb.h"
41 #include "opt_hwpmc_hooks.h"
42 #include "opt_sched.h"
43 #include "opt_thrworkq.h"
44
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/bus.h>
48 #include <sys/conf.h>
49 #include <sys/kdb.h>
50 #include <sys/kernel.h>
51 #include <sys/ktr.h>
52 #include <sys/lock.h>
53 #include <sys/malloc.h>
54 #include <sys/mutex.h>
55 #include <sys/proc.h>
56 #include <sys/resourcevar.h>
57 #include <sys/sched.h>
58 #include <sys/sbuf.h>
59 #include <sys/sysctl.h>
60 #include <sys/turnstile.h>
61 #include <sys/vmmeter.h>
62 #include <sys/lock_profile.h>
63
64 #include <machine/atomic.h>
65 #include <machine/bus.h>
66 #include <machine/cpu.h>
67
68 #include <ddb/ddb.h>
69
70 #include <fs/devfs/devfs_int.h>
71
72 #include <vm/vm.h>
73 #include <vm/vm_extern.h>
74
75 #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
76 #define ADAPTIVE_MUTEXES
77 #endif
78
79 #ifdef HWPMC_HOOKS
80 #include <sys/pmckern.h>
81 PMC_SOFT_DEFINE( , , lock, failed);
82 #endif
83
84 /*
85 * Return the mutex address when the lock cookie address is provided.
86 * This functionality assumes that struct mtx* have a member named mtx_lock.
87 */
88 #define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock))
89
90 /*
91 * Internal utility macros.
92 */
93 #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
94
95 #define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED)
96
97 #define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK))
98
99 static void assert_mtx(const struct lock_object *lock, int what);
100 #ifdef DDB
101 static void db_show_mtx(const struct lock_object *lock);
102 #endif
103 static void lock_mtx(struct lock_object *lock, uintptr_t how);
104 static void lock_spin(struct lock_object *lock, uintptr_t how);
105 #ifdef KDTRACE_HOOKS
106 static int owner_mtx(const struct lock_object *lock,
107 struct thread **owner);
108 #endif
109 static uintptr_t unlock_mtx(struct lock_object *lock);
110 static uintptr_t unlock_spin(struct lock_object *lock);
111
112 /*
113 * Lock classes for sleep and spin mutexes.
114 */
115 struct lock_class lock_class_mtx_sleep = {
116 .lc_name = "sleep mutex",
117 .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE,
118 .lc_assert = assert_mtx,
119 #ifdef DDB
120 .lc_ddb_show = db_show_mtx,
121 #endif
122 .lc_lock = lock_mtx,
123 .lc_unlock = unlock_mtx,
124 #ifdef KDTRACE_HOOKS
125 .lc_owner = owner_mtx,
126 #endif
127 };
128 struct lock_class lock_class_mtx_spin = {
129 .lc_name = "spin mutex",
130 .lc_flags = LC_SPINLOCK | LC_RECURSABLE,
131 .lc_assert = assert_mtx,
132 #ifdef DDB
133 .lc_ddb_show = db_show_mtx,
134 #endif
135 .lc_lock = lock_spin,
136 .lc_unlock = unlock_spin,
137 #ifdef KDTRACE_HOOKS
138 .lc_owner = owner_mtx,
139 #endif
140 };
141
142 /*
143 * System-wide mutexes
144 */
145 struct mtx blocked_lock;
146 struct mtx Giant;
147
148 void
assert_mtx(const struct lock_object * lock,int what)149 assert_mtx(const struct lock_object *lock, int what)
150 {
151
152 mtx_assert((const struct mtx *)lock, what);
153 }
154
155 void
lock_mtx(struct lock_object * lock,uintptr_t how)156 lock_mtx(struct lock_object *lock, uintptr_t how)
157 {
158
159 mtx_lock((struct mtx *)lock);
160 }
161
162 void
lock_spin(struct lock_object * lock,uintptr_t how)163 lock_spin(struct lock_object *lock, uintptr_t how)
164 {
165
166 panic("spin locks can only use msleep_spin");
167 }
168
169 uintptr_t
unlock_mtx(struct lock_object * lock)170 unlock_mtx(struct lock_object *lock)
171 {
172 struct mtx *m;
173
174 m = (struct mtx *)lock;
175 mtx_assert(m, MA_OWNED | MA_NOTRECURSED);
176 mtx_unlock(m);
177 return (0);
178 }
179
180 uintptr_t
unlock_spin(struct lock_object * lock)181 unlock_spin(struct lock_object *lock)
182 {
183
184 panic("spin locks can only use msleep_spin");
185 }
186
187 #ifdef KDTRACE_HOOKS
188 int
owner_mtx(const struct lock_object * lock,struct thread ** owner)189 owner_mtx(const struct lock_object *lock, struct thread **owner)
190 {
191 const struct mtx *m = (const struct mtx *)lock;
192
193 *owner = mtx_owner(m);
194 return (mtx_unowned(m) == 0);
195 }
196 #endif
197
198 /*
199 * Function versions of the inlined __mtx_* macros. These are used by
200 * modules and can also be called from assembly language if needed.
201 */
202 void
__mtx_lock_flags(volatile uintptr_t * c,int opts,const char * file,int line)203 __mtx_lock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
204 {
205 struct mtx *m;
206
207 if (SCHEDULER_STOPPED())
208 return;
209
210 m = mtxlock2mtx(c);
211
212 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
213 ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d",
214 curthread, m->lock_object.lo_name, file, line));
215 KASSERT(m->mtx_lock != MTX_DESTROYED,
216 ("mtx_lock() of destroyed mutex @ %s:%d", file, line));
217 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
218 ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
219 file, line));
220 WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) |
221 LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
222
223 __mtx_lock(m, curthread, opts, file, line);
224 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
225 line);
226 WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE,
227 file, line);
228 TD_LOCKS_INC(curthread);
229 }
230
231 void
__mtx_unlock_flags(volatile uintptr_t * c,int opts,const char * file,int line)232 __mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line)
233 {
234 struct mtx *m;
235
236 if (SCHEDULER_STOPPED())
237 return;
238
239 m = mtxlock2mtx(c);
240
241 KASSERT(m->mtx_lock != MTX_DESTROYED,
242 ("mtx_unlock() of destroyed mutex @ %s:%d", file, line));
243 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
244 ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
245 file, line));
246 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
247 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
248 line);
249 mtx_assert(m, MA_OWNED);
250
251 __mtx_unlock(m, curthread, opts, file, line);
252 TD_LOCKS_DEC(curthread);
253 }
254
255 void
__mtx_lock_spin_flags(volatile uintptr_t * c,int opts,const char * file,int line)256 __mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
257 int line)
258 {
259 struct mtx *m;
260
261 if (SCHEDULER_STOPPED())
262 return;
263
264 m = mtxlock2mtx(c);
265
266 KASSERT(m->mtx_lock != MTX_DESTROYED,
267 ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line));
268 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
269 ("mtx_lock_spin() of sleep mutex %s @ %s:%d",
270 m->lock_object.lo_name, file, line));
271 if (mtx_owned(m))
272 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
273 (opts & MTX_RECURSE) != 0,
274 ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n",
275 m->lock_object.lo_name, file, line));
276 opts &= ~MTX_RECURSE;
277 WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
278 file, line, NULL);
279 __mtx_lock_spin(m, curthread, opts, file, line);
280 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
281 line);
282 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
283 }
284
285 void
__mtx_unlock_spin_flags(volatile uintptr_t * c,int opts,const char * file,int line)286 __mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file,
287 int line)
288 {
289 struct mtx *m;
290
291 if (SCHEDULER_STOPPED())
292 return;
293
294 m = mtxlock2mtx(c);
295
296 KASSERT(m->mtx_lock != MTX_DESTROYED,
297 ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line));
298 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
299 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
300 m->lock_object.lo_name, file, line));
301 WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
302 LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file,
303 line);
304 mtx_assert(m, MA_OWNED);
305
306 __mtx_unlock_spin(m);
307 }
308
309 /*
310 * The important part of mtx_trylock{,_flags}()
311 * Tries to acquire lock `m.' If this function is called on a mutex that
312 * is already owned, it will recursively acquire the lock.
313 */
314 int
_mtx_trylock_flags_(volatile uintptr_t * c,int opts,const char * file,int line)315 _mtx_trylock_flags_(volatile uintptr_t *c, int opts, const char *file, int line)
316 {
317 struct mtx *m;
318 #ifdef LOCK_PROFILING
319 uint64_t waittime = 0;
320 int contested = 0;
321 #endif
322 int rval;
323
324 if (SCHEDULER_STOPPED())
325 return (1);
326
327 m = mtxlock2mtx(c);
328
329 KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread),
330 ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d",
331 curthread, m->lock_object.lo_name, file, line));
332 KASSERT(m->mtx_lock != MTX_DESTROYED,
333 ("mtx_trylock() of destroyed mutex @ %s:%d", file, line));
334 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep,
335 ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name,
336 file, line));
337
338 if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
339 (opts & MTX_RECURSE) != 0)) {
340 m->mtx_recurse++;
341 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
342 rval = 1;
343 } else
344 rval = _mtx_obtain_lock(m, (uintptr_t)curthread);
345 opts &= ~MTX_RECURSE;
346
347 LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line);
348 if (rval) {
349 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
350 file, line);
351 TD_LOCKS_INC(curthread);
352 if (m->mtx_recurse == 0)
353 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire,
354 m, contested, waittime, file, line);
355
356 }
357
358 return (rval);
359 }
360
361 /*
362 * __mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
363 *
364 * We call this if the lock is either contested (i.e. we need to go to
365 * sleep waiting for it), or if we need to recurse on it.
366 */
367 void
__mtx_lock_sleep(volatile uintptr_t * c,uintptr_t tid,int opts,const char * file,int line)368 __mtx_lock_sleep(volatile uintptr_t *c, uintptr_t tid, int opts,
369 const char *file, int line)
370 {
371 struct mtx *m;
372 struct turnstile *ts;
373 uintptr_t v;
374 #ifdef ADAPTIVE_MUTEXES
375 volatile struct thread *owner;
376 #endif
377 #ifdef KTR
378 int cont_logged = 0;
379 #endif
380 #ifdef LOCK_PROFILING
381 int contested = 0;
382 uint64_t waittime = 0;
383 #endif
384 #ifdef KDTRACE_HOOKS
385 uint64_t spin_cnt = 0;
386 uint64_t sleep_cnt = 0;
387 int64_t sleep_time = 0;
388 int64_t all_time = 0;
389 #endif
390
391 if (SCHEDULER_STOPPED())
392 return;
393
394 m = mtxlock2mtx(c);
395
396 if (mtx_owned(m)) {
397 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 ||
398 (opts & MTX_RECURSE) != 0,
399 ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
400 m->lock_object.lo_name, file, line));
401 opts &= ~MTX_RECURSE;
402 m->mtx_recurse++;
403 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
404 if (LOCK_LOG_TEST(&m->lock_object, opts))
405 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
406 return;
407 }
408 opts &= ~MTX_RECURSE;
409
410 #ifdef HWPMC_HOOKS
411 PMC_SOFT_CALL( , , lock, failed);
412 #endif
413 lock_profile_obtain_lock_failed(&m->lock_object,
414 &contested, &waittime);
415 if (LOCK_LOG_TEST(&m->lock_object, opts))
416 CTR4(KTR_LOCK,
417 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
418 m->lock_object.lo_name, (void *)m->mtx_lock, file, line);
419 #ifdef KDTRACE_HOOKS
420 all_time -= lockstat_nsecs(&m->lock_object);
421 #endif
422
423 while (!_mtx_obtain_lock(m, tid)) {
424 #ifdef KDTRACE_HOOKS
425 spin_cnt++;
426 #endif
427 #ifdef ADAPTIVE_MUTEXES
428 /*
429 * If the owner is running on another CPU, spin until the
430 * owner stops running or the state of the lock changes.
431 */
432 v = m->mtx_lock;
433 if (v != MTX_UNOWNED) {
434 owner = (struct thread *)(v & ~MTX_FLAGMASK);
435 if (TD_IS_RUNNING(owner)) {
436 if (LOCK_LOG_TEST(&m->lock_object, 0))
437 CTR3(KTR_LOCK,
438 "%s: spinning on %p held by %p",
439 __func__, m, owner);
440 KTR_STATE1(KTR_SCHED, "thread",
441 sched_tdname((struct thread *)tid),
442 "spinning", "lockname:\"%s\"",
443 m->lock_object.lo_name);
444 while (mtx_owner(m) == owner &&
445 TD_IS_RUNNING(owner)) {
446 cpu_spinwait();
447 #ifdef KDTRACE_HOOKS
448 spin_cnt++;
449 #endif
450 }
451 KTR_STATE0(KTR_SCHED, "thread",
452 sched_tdname((struct thread *)tid),
453 "running");
454 continue;
455 }
456 }
457 #endif
458
459 ts = turnstile_trywait(&m->lock_object);
460 v = m->mtx_lock;
461
462 /*
463 * Check if the lock has been released while spinning for
464 * the turnstile chain lock.
465 */
466 if (v == MTX_UNOWNED) {
467 turnstile_cancel(ts);
468 continue;
469 }
470
471 #ifdef ADAPTIVE_MUTEXES
472 /*
473 * The current lock owner might have started executing
474 * on another CPU (or the lock could have changed
475 * owners) while we were waiting on the turnstile
476 * chain lock. If so, drop the turnstile lock and try
477 * again.
478 */
479 owner = (struct thread *)(v & ~MTX_FLAGMASK);
480 if (TD_IS_RUNNING(owner)) {
481 turnstile_cancel(ts);
482 continue;
483 }
484 #endif
485
486 /*
487 * If the mutex isn't already contested and a failure occurs
488 * setting the contested bit, the mutex was either released
489 * or the state of the MTX_RECURSED bit changed.
490 */
491 if ((v & MTX_CONTESTED) == 0 &&
492 !atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) {
493 turnstile_cancel(ts);
494 continue;
495 }
496
497 /*
498 * We definitely must sleep for this lock.
499 */
500 mtx_assert(m, MA_NOTOWNED);
501
502 #ifdef KTR
503 if (!cont_logged) {
504 CTR6(KTR_CONTENTION,
505 "contention: %p at %s:%d wants %s, taken by %s:%d",
506 (void *)tid, file, line, m->lock_object.lo_name,
507 WITNESS_FILE(&m->lock_object),
508 WITNESS_LINE(&m->lock_object));
509 cont_logged = 1;
510 }
511 #endif
512
513 /*
514 * Block on the turnstile.
515 */
516 #ifdef KDTRACE_HOOKS
517 sleep_time -= lockstat_nsecs(&m->lock_object);
518 #endif
519 turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE);
520 #ifdef KDTRACE_HOOKS
521 sleep_time += lockstat_nsecs(&m->lock_object);
522 sleep_cnt++;
523 #endif
524 }
525 #ifdef KDTRACE_HOOKS
526 all_time += lockstat_nsecs(&m->lock_object);
527 #endif
528 #ifdef KTR
529 if (cont_logged) {
530 CTR4(KTR_CONTENTION,
531 "contention end: %s acquired by %p at %s:%d",
532 m->lock_object.lo_name, (void *)tid, file, line);
533 }
534 #endif
535 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(adaptive__acquire, m, contested,
536 waittime, file, line);
537 #ifdef KDTRACE_HOOKS
538 if (sleep_time)
539 LOCKSTAT_RECORD1(adaptive__block, m, sleep_time);
540
541 /*
542 * Only record the loops spinning and not sleeping.
543 */
544 if (spin_cnt > sleep_cnt)
545 LOCKSTAT_RECORD1(adaptive__spin, m, all_time - sleep_time);
546 #endif
547 }
548
549 static void
_mtx_lock_spin_failed(struct mtx * m)550 _mtx_lock_spin_failed(struct mtx *m)
551 {
552 struct thread *td;
553
554 td = mtx_owner(m);
555
556 /* If the mutex is unlocked, try again. */
557 if (td == NULL)
558 return;
559
560 printf( "spin lock %p (%s) held by %p (tid %d) too long\n",
561 m, m->lock_object.lo_name, td, td->td_tid);
562 #ifdef WITNESS
563 witness_display_spinlock(&m->lock_object, td, printf);
564 #endif
565 panic("spin lock held too long");
566 }
567
568 #ifdef SMP
569 /*
570 * _mtx_lock_spin_cookie: the tougher part of acquiring an MTX_SPIN lock.
571 *
572 * This is only called if we need to actually spin for the lock. Recursion
573 * is handled inline.
574 */
575 void
_mtx_lock_spin_cookie(volatile uintptr_t * c,uintptr_t tid,int opts,const char * file,int line)576 _mtx_lock_spin_cookie(volatile uintptr_t *c, uintptr_t tid, int opts,
577 const char *file, int line)
578 {
579 struct mtx *m;
580 int i = 0;
581 #ifdef LOCK_PROFILING
582 int contested = 0;
583 uint64_t waittime = 0;
584 #endif
585 #ifdef KDTRACE_HOOKS
586 int64_t spin_time = 0;
587 #endif
588
589 if (SCHEDULER_STOPPED())
590 return;
591
592 m = mtxlock2mtx(c);
593
594 if (LOCK_LOG_TEST(&m->lock_object, opts))
595 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
596 KTR_STATE1(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
597 "spinning", "lockname:\"%s\"", m->lock_object.lo_name);
598
599 #ifdef HWPMC_HOOKS
600 PMC_SOFT_CALL( , , lock, failed);
601 #endif
602 lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime);
603 #ifdef KDTRACE_HOOKS
604 spin_time -= lockstat_nsecs(&m->lock_object);
605 #endif
606 while (!_mtx_obtain_lock(m, tid)) {
607
608 /* Give interrupts a chance while we spin. */
609 spinlock_exit();
610 while (m->mtx_lock != MTX_UNOWNED) {
611 if (i++ < 10000000) {
612 cpu_spinwait();
613 continue;
614 }
615 if (i < 60000000 || kdb_active || panicstr != NULL)
616 DELAY(1);
617 else
618 _mtx_lock_spin_failed(m);
619 cpu_spinwait();
620 }
621 spinlock_enter();
622 }
623 #ifdef KDTRACE_HOOKS
624 spin_time += lockstat_nsecs(&m->lock_object);
625 #endif
626
627 if (LOCK_LOG_TEST(&m->lock_object, opts))
628 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
629 KTR_STATE0(KTR_SCHED, "thread", sched_tdname((struct thread *)tid),
630 "running");
631
632 #ifdef KDTRACE_HOOKS
633 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m,
634 contested, waittime, file, line);
635 if (spin_time != 0)
636 LOCKSTAT_RECORD1(spin__spin, m, spin_time);
637 #endif
638 }
639 #endif /* SMP */
640
641 void
thread_lock_flags_(struct thread * td,int opts,const char * file,int line)642 thread_lock_flags_(struct thread *td, int opts, const char *file, int line)
643 {
644 struct mtx *m;
645 uintptr_t tid;
646 int i;
647 #ifdef LOCK_PROFILING
648 int contested = 0;
649 uint64_t waittime = 0;
650 #endif
651 #ifdef KDTRACE_HOOKS
652 int64_t spin_time = 0;
653 #endif
654
655 i = 0;
656 tid = (uintptr_t)curthread;
657
658 if (SCHEDULER_STOPPED())
659 return;
660
661 #ifdef KDTRACE_HOOKS
662 spin_time -= lockstat_nsecs(&td->td_lock->lock_object);
663 #endif
664 for (;;) {
665 retry:
666 spinlock_enter();
667 m = td->td_lock;
668 KASSERT(m->mtx_lock != MTX_DESTROYED,
669 ("thread_lock() of destroyed mutex @ %s:%d", file, line));
670 KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin,
671 ("thread_lock() of sleep mutex %s @ %s:%d",
672 m->lock_object.lo_name, file, line));
673 if (mtx_owned(m))
674 KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0,
675 ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n",
676 m->lock_object.lo_name, file, line));
677 WITNESS_CHECKORDER(&m->lock_object,
678 opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL);
679 while (!_mtx_obtain_lock(m, tid)) {
680 if (m->mtx_lock == tid) {
681 m->mtx_recurse++;
682 break;
683 }
684 #ifdef HWPMC_HOOKS
685 PMC_SOFT_CALL( , , lock, failed);
686 #endif
687 lock_profile_obtain_lock_failed(&m->lock_object,
688 &contested, &waittime);
689 /* Give interrupts a chance while we spin. */
690 spinlock_exit();
691 while (m->mtx_lock != MTX_UNOWNED) {
692 if (i++ < 10000000)
693 cpu_spinwait();
694 else if (i < 60000000 ||
695 kdb_active || panicstr != NULL)
696 DELAY(1);
697 else
698 _mtx_lock_spin_failed(m);
699 cpu_spinwait();
700 if (m != td->td_lock)
701 goto retry;
702 }
703 spinlock_enter();
704 }
705 if (m == td->td_lock)
706 break;
707 __mtx_unlock_spin(m); /* does spinlock_exit() */
708 }
709 #ifdef KDTRACE_HOOKS
710 spin_time += lockstat_nsecs(&m->lock_object);
711 #endif
712 if (m->mtx_recurse == 0)
713 LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(spin__acquire, m,
714 contested, waittime, file, line);
715 LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file,
716 line);
717 WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line);
718 LOCKSTAT_RECORD1(thread__spin, m, spin_time);
719 }
720
721 struct mtx *
thread_lock_block(struct thread * td)722 thread_lock_block(struct thread *td)
723 {
724 struct mtx *lock;
725
726 THREAD_LOCK_ASSERT(td, MA_OWNED);
727 lock = td->td_lock;
728 td->td_lock = &blocked_lock;
729 mtx_unlock_spin(lock);
730
731 return (lock);
732 }
733
734 void
thread_lock_unblock(struct thread * td,struct mtx * new)735 thread_lock_unblock(struct thread *td, struct mtx *new)
736 {
737 mtx_assert(new, MA_OWNED);
738 MPASS(td->td_lock == &blocked_lock);
739 atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new);
740 }
741
742 void
thread_lock_set(struct thread * td,struct mtx * new)743 thread_lock_set(struct thread *td, struct mtx *new)
744 {
745 struct mtx *lock;
746
747 mtx_assert(new, MA_OWNED);
748 THREAD_LOCK_ASSERT(td, MA_OWNED);
749 lock = td->td_lock;
750 td->td_lock = new;
751 mtx_unlock_spin(lock);
752 }
753
754 /*
755 * __mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
756 *
757 * We are only called here if the lock is recursed or contested (i.e. we
758 * need to wake up a blocked thread).
759 */
760 void
__mtx_unlock_sleep(volatile uintptr_t * c,int opts,const char * file,int line)761 __mtx_unlock_sleep(volatile uintptr_t *c, int opts, const char *file, int line)
762 {
763 struct mtx *m;
764 struct turnstile *ts;
765
766 if (SCHEDULER_STOPPED())
767 return;
768
769 m = mtxlock2mtx(c);
770
771 if (mtx_recursed(m)) {
772 if (--(m->mtx_recurse) == 0)
773 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
774 if (LOCK_LOG_TEST(&m->lock_object, opts))
775 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
776 return;
777 }
778
779 /*
780 * We have to lock the chain before the turnstile so this turnstile
781 * can be removed from the hash list if it is empty.
782 */
783 turnstile_chain_lock(&m->lock_object);
784 ts = turnstile_lookup(&m->lock_object);
785 if (LOCK_LOG_TEST(&m->lock_object, opts))
786 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
787 MPASS(ts != NULL);
788 turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE);
789 _mtx_release_lock_quick(m);
790
791 /*
792 * This turnstile is now no longer associated with the mutex. We can
793 * unlock the chain lock so a new turnstile may take it's place.
794 */
795 turnstile_unpend(ts, TS_EXCLUSIVE_LOCK);
796 turnstile_chain_unlock(&m->lock_object);
797 }
798
799 /*
800 * All the unlocking of MTX_SPIN locks is done inline.
801 * See the __mtx_unlock_spin() macro for the details.
802 */
803
804 /*
805 * The backing function for the INVARIANTS-enabled mtx_assert()
806 */
807 #ifdef INVARIANT_SUPPORT
808 void
__mtx_assert(const volatile uintptr_t * c,int what,const char * file,int line)809 __mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line)
810 {
811 const struct mtx *m;
812
813 if (panicstr != NULL || dumping)
814 return;
815
816 m = mtxlock2mtx(c);
817
818 switch (what) {
819 case MA_OWNED:
820 case MA_OWNED | MA_RECURSED:
821 case MA_OWNED | MA_NOTRECURSED:
822 if (!mtx_owned(m))
823 panic("mutex %s not owned at %s:%d",
824 m->lock_object.lo_name, file, line);
825 if (mtx_recursed(m)) {
826 if ((what & MA_NOTRECURSED) != 0)
827 panic("mutex %s recursed at %s:%d",
828 m->lock_object.lo_name, file, line);
829 } else if ((what & MA_RECURSED) != 0) {
830 panic("mutex %s unrecursed at %s:%d",
831 m->lock_object.lo_name, file, line);
832 }
833 break;
834 case MA_NOTOWNED:
835 if (mtx_owned(m))
836 panic("mutex %s owned at %s:%d",
837 m->lock_object.lo_name, file, line);
838 break;
839 default:
840 panic("unknown mtx_assert at %s:%d", file, line);
841 }
842 }
843 #endif
844
845 /*
846 * The MUTEX_DEBUG-enabled mtx_validate()
847 *
848 * Most of these checks have been moved off into the LO_INITIALIZED flag
849 * maintained by the witness code.
850 */
851 #ifdef MUTEX_DEBUG
852
853 void mtx_validate(struct mtx *);
854
855 void
mtx_validate(struct mtx * m)856 mtx_validate(struct mtx *m)
857 {
858
859 /*
860 * XXX: When kernacc() does not require Giant we can reenable this check
861 */
862 #ifdef notyet
863 /*
864 * Can't call kernacc() from early init386(), especially when
865 * initializing Giant mutex, because some stuff in kernacc()
866 * requires Giant itself.
867 */
868 if (!cold)
869 if (!kernacc((caddr_t)m, sizeof(m),
870 VM_PROT_READ | VM_PROT_WRITE))
871 panic("Can't read and write to mutex %p", m);
872 #endif
873 }
874 #endif
875
876 /*
877 * General init routine used by the MTX_SYSINIT() macro.
878 */
879 void
mtx_sysinit(void * arg)880 mtx_sysinit(void *arg)
881 {
882 struct mtx_args *margs = arg;
883
884 mtx_init((struct mtx *)margs->ma_mtx, margs->ma_desc, NULL,
885 margs->ma_opts);
886 }
887
888 /*
889 * Mutex initialization routine; initialize lock `m' of type contained in
890 * `opts' with options contained in `opts' and name `name.' The optional
891 * lock type `type' is used as a general lock category name for use with
892 * witness.
893 */
894 void
_mtx_init(volatile uintptr_t * c,const char * name,const char * type,int opts)895 _mtx_init(volatile uintptr_t *c, const char *name, const char *type, int opts)
896 {
897 struct mtx *m;
898 struct lock_class *class;
899 int flags;
900
901 m = mtxlock2mtx(c);
902
903 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
904 MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE | MTX_NEW)) == 0);
905 ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock,
906 ("%s: mtx_lock not aligned for %s: %p", __func__, name,
907 &m->mtx_lock));
908
909 #ifdef MUTEX_DEBUG
910 /* Diagnostic and error correction */
911 mtx_validate(m);
912 #endif
913
914 /* Determine lock class and lock flags. */
915 if (opts & MTX_SPIN)
916 class = &lock_class_mtx_spin;
917 else
918 class = &lock_class_mtx_sleep;
919 flags = 0;
920 if (opts & MTX_QUIET)
921 flags |= LO_QUIET;
922 if (opts & MTX_RECURSE)
923 flags |= LO_RECURSABLE;
924 if ((opts & MTX_NOWITNESS) == 0)
925 flags |= LO_WITNESS;
926 if (opts & MTX_DUPOK)
927 flags |= LO_DUPOK;
928 if (opts & MTX_NOPROFILE)
929 flags |= LO_NOPROFILE;
930 if (opts & MTX_NEW)
931 flags |= LO_NEW;
932
933 /* Initialize mutex. */
934 lock_init(&m->lock_object, class, name, type, flags);
935
936 m->mtx_lock = MTX_UNOWNED;
937 m->mtx_recurse = 0;
938 }
939
940 /*
941 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
942 * passed in as a flag here because if the corresponding mtx_init() was
943 * called with MTX_QUIET set, then it will already be set in the mutex's
944 * flags.
945 */
946 void
_mtx_destroy(volatile uintptr_t * c)947 _mtx_destroy(volatile uintptr_t *c)
948 {
949 struct mtx *m;
950
951 m = mtxlock2mtx(c);
952
953 if (!mtx_owned(m))
954 MPASS(mtx_unowned(m));
955 else {
956 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
957
958 /* Perform the non-mtx related part of mtx_unlock_spin(). */
959 if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin)
960 spinlock_exit();
961 else
962 TD_LOCKS_DEC(curthread);
963
964 lock_profile_release_lock(&m->lock_object);
965 /* Tell witness this isn't locked to make it happy. */
966 WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__,
967 __LINE__);
968 }
969
970 m->mtx_lock = MTX_DESTROYED;
971 lock_destroy(&m->lock_object);
972 }
973
974 /*
975 * Intialize the mutex code and system mutexes. This is called from the MD
976 * startup code prior to mi_startup(). The per-CPU data space needs to be
977 * setup before this is called.
978 */
979 void
mutex_init(void)980 mutex_init(void)
981 {
982
983 /* Setup turnstiles so that sleep mutexes work. */
984 init_turnstiles();
985
986 /*
987 * Initialize mutexes.
988 */
989 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
990 mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN);
991 blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */
992 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
993 mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN);
994 #ifdef THRWORKQ
995 mtx_init(&proc0.p_twqlock, "thr workq lock", NULL, MTX_DEF | MTX_DUPOK);
996 proc0.p_twq = NULL;
997 #endif /* THRWORKQ */
998 mtx_init(&proc0.p_statmtx, "pstatl", NULL, MTX_SPIN);
999 mtx_init(&proc0.p_itimmtx, "pitiml", NULL, MTX_SPIN);
1000 mtx_init(&proc0.p_profmtx, "pprofl", NULL, MTX_SPIN);
1001 mtx_init(&devmtx, "cdev", NULL, MTX_DEF);
1002 mtx_lock(&Giant);
1003 }
1004
1005 #ifdef DDB
1006 void
db_show_mtx(const struct lock_object * lock)1007 db_show_mtx(const struct lock_object *lock)
1008 {
1009 struct thread *td;
1010 const struct mtx *m;
1011
1012 m = (const struct mtx *)lock;
1013
1014 db_printf(" flags: {");
1015 if (LOCK_CLASS(lock) == &lock_class_mtx_spin)
1016 db_printf("SPIN");
1017 else
1018 db_printf("DEF");
1019 if (m->lock_object.lo_flags & LO_RECURSABLE)
1020 db_printf(", RECURSE");
1021 if (m->lock_object.lo_flags & LO_DUPOK)
1022 db_printf(", DUPOK");
1023 db_printf("}\n");
1024 db_printf(" state: {");
1025 if (mtx_unowned(m))
1026 db_printf("UNOWNED");
1027 else if (mtx_destroyed(m))
1028 db_printf("DESTROYED");
1029 else {
1030 db_printf("OWNED");
1031 if (m->mtx_lock & MTX_CONTESTED)
1032 db_printf(", CONTESTED");
1033 if (m->mtx_lock & MTX_RECURSED)
1034 db_printf(", RECURSED");
1035 }
1036 db_printf("}\n");
1037 if (!mtx_unowned(m) && !mtx_destroyed(m)) {
1038 td = mtx_owner(m);
1039 db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td,
1040 td->td_tid, td->td_proc->p_pid, td->td_name);
1041 if (mtx_recursed(m))
1042 db_printf(" recursed: %d\n", m->mtx_recurse);
1043 }
1044 }
1045 #endif
1046