xref: /freebsd/sys/kern/subr_lock.c (revision 39ee7a7a6bdd1557b1c3532abf60d139798ac88b)
1 /*-
2  * Copyright (c) 2006 John Baldwin <jhb@FreeBSD.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 /*
28  * This module holds the global variables and functions used to maintain
29  * lock_object structures.
30  */
31 
32 #include <sys/cdefs.h>
33 __FBSDID("$FreeBSD$");
34 
35 #include "opt_ddb.h"
36 #include "opt_mprof.h"
37 
38 #include <sys/param.h>
39 #include <sys/systm.h>
40 #include <sys/kernel.h>
41 #include <sys/ktr.h>
42 #include <sys/lock.h>
43 #include <sys/lock_profile.h>
44 #include <sys/malloc.h>
45 #include <sys/mutex.h>
46 #include <sys/pcpu.h>
47 #include <sys/proc.h>
48 #include <sys/sbuf.h>
49 #include <sys/sched.h>
50 #include <sys/smp.h>
51 #include <sys/sysctl.h>
52 
53 #ifdef DDB
54 #include <ddb/ddb.h>
55 #endif
56 
57 #include <machine/cpufunc.h>
58 
59 CTASSERT(LOCK_CLASS_MAX == 15);
60 
61 struct lock_class *lock_classes[LOCK_CLASS_MAX + 1] = {
62 	&lock_class_mtx_spin,
63 	&lock_class_mtx_sleep,
64 	&lock_class_sx,
65 	&lock_class_rm,
66 	&lock_class_rm_sleepable,
67 	&lock_class_rw,
68 	&lock_class_lockmgr,
69 };
70 
71 void
72 lock_init(struct lock_object *lock, struct lock_class *class, const char *name,
73     const char *type, int flags)
74 {
75 	int i;
76 
77 	/* Check for double-init and zero object. */
78 	KASSERT(flags & LO_NEW || !lock_initialized(lock),
79 	    ("lock \"%s\" %p already initialized", name, lock));
80 
81 	/* Look up lock class to find its index. */
82 	for (i = 0; i < LOCK_CLASS_MAX; i++)
83 		if (lock_classes[i] == class) {
84 			lock->lo_flags = i << LO_CLASSSHIFT;
85 			break;
86 		}
87 	KASSERT(i < LOCK_CLASS_MAX, ("unknown lock class %p", class));
88 
89 	/* Initialize the lock object. */
90 	lock->lo_name = name;
91 	lock->lo_flags |= flags | LO_INITIALIZED;
92 	LOCK_LOG_INIT(lock, 0);
93 	WITNESS_INIT(lock, (type != NULL) ? type : name);
94 }
95 
96 void
97 lock_destroy(struct lock_object *lock)
98 {
99 
100 	KASSERT(lock_initialized(lock), ("lock %p is not initialized", lock));
101 	WITNESS_DESTROY(lock);
102 	LOCK_LOG_DESTROY(lock, 0);
103 	lock->lo_flags &= ~LO_INITIALIZED;
104 }
105 
106 #ifdef DDB
107 DB_SHOW_COMMAND(lock, db_show_lock)
108 {
109 	struct lock_object *lock;
110 	struct lock_class *class;
111 
112 	if (!have_addr)
113 		return;
114 	lock = (struct lock_object *)addr;
115 	if (LO_CLASSINDEX(lock) > LOCK_CLASS_MAX) {
116 		db_printf("Unknown lock class: %d\n", LO_CLASSINDEX(lock));
117 		return;
118 	}
119 	class = LOCK_CLASS(lock);
120 	db_printf(" class: %s\n", class->lc_name);
121 	db_printf(" name: %s\n", lock->lo_name);
122 	class->lc_ddb_show(lock);
123 }
124 #endif
125 
126 #ifdef LOCK_PROFILING
127 
128 /*
129  * One object per-thread for each lock the thread owns.  Tracks individual
130  * lock instances.
131  */
132 struct lock_profile_object {
133 	LIST_ENTRY(lock_profile_object) lpo_link;
134 	struct lock_object *lpo_obj;
135 	const char	*lpo_file;
136 	int		lpo_line;
137 	uint16_t	lpo_ref;
138 	uint16_t	lpo_cnt;
139 	uint64_t	lpo_acqtime;
140 	uint64_t	lpo_waittime;
141 	u_int		lpo_contest_locking;
142 };
143 
144 /*
145  * One lock_prof for each (file, line, lock object) triple.
146  */
147 struct lock_prof {
148 	SLIST_ENTRY(lock_prof) link;
149 	struct lock_class *class;
150 	const char	*file;
151 	const char	*name;
152 	int		line;
153 	int		ticks;
154 	uintmax_t	cnt_wait_max;
155 	uintmax_t	cnt_max;
156 	uintmax_t	cnt_tot;
157 	uintmax_t	cnt_wait;
158 	uintmax_t	cnt_cur;
159 	uintmax_t	cnt_contest_locking;
160 };
161 
162 SLIST_HEAD(lphead, lock_prof);
163 
164 #define	LPROF_HASH_SIZE		4096
165 #define	LPROF_HASH_MASK		(LPROF_HASH_SIZE - 1)
166 #define	LPROF_CACHE_SIZE	4096
167 
168 /*
169  * Array of objects and profs for each type of object for each cpu.  Spinlocks
170  * are handled separately because a thread may be preempted and acquire a
171  * spinlock while in the lock profiling code of a non-spinlock.  In this way
172  * we only need a critical section to protect the per-cpu lists.
173  */
174 struct lock_prof_type {
175 	struct lphead		lpt_lpalloc;
176 	struct lpohead		lpt_lpoalloc;
177 	struct lphead		lpt_hash[LPROF_HASH_SIZE];
178 	struct lock_prof	lpt_prof[LPROF_CACHE_SIZE];
179 	struct lock_profile_object lpt_objs[LPROF_CACHE_SIZE];
180 };
181 
182 struct lock_prof_cpu {
183 	struct lock_prof_type	lpc_types[2]; /* One for spin one for other. */
184 };
185 
186 struct lock_prof_cpu *lp_cpu[MAXCPU];
187 
188 volatile int lock_prof_enable = 0;
189 static volatile int lock_prof_resetting;
190 
191 #define LPROF_SBUF_SIZE		256
192 
193 static int lock_prof_rejected;
194 static int lock_prof_skipspin;
195 static int lock_prof_skipcount;
196 
197 #ifndef USE_CPU_NANOSECONDS
198 uint64_t
199 nanoseconds(void)
200 {
201 	struct bintime bt;
202 	uint64_t ns;
203 
204 	binuptime(&bt);
205 	/* From bintime2timespec */
206 	ns = bt.sec * (uint64_t)1000000000;
207 	ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32;
208 	return (ns);
209 }
210 #endif
211 
212 static void
213 lock_prof_init_type(struct lock_prof_type *type)
214 {
215 	int i;
216 
217 	SLIST_INIT(&type->lpt_lpalloc);
218 	LIST_INIT(&type->lpt_lpoalloc);
219 	for (i = 0; i < LPROF_CACHE_SIZE; i++) {
220 		SLIST_INSERT_HEAD(&type->lpt_lpalloc, &type->lpt_prof[i],
221 		    link);
222 		LIST_INSERT_HEAD(&type->lpt_lpoalloc, &type->lpt_objs[i],
223 		    lpo_link);
224 	}
225 }
226 
227 static void
228 lock_prof_init(void *arg)
229 {
230 	int cpu;
231 
232 	for (cpu = 0; cpu <= mp_maxid; cpu++) {
233 		lp_cpu[cpu] = malloc(sizeof(*lp_cpu[cpu]), M_DEVBUF,
234 		    M_WAITOK | M_ZERO);
235 		lock_prof_init_type(&lp_cpu[cpu]->lpc_types[0]);
236 		lock_prof_init_type(&lp_cpu[cpu]->lpc_types[1]);
237 	}
238 }
239 SYSINIT(lockprof, SI_SUB_SMP, SI_ORDER_ANY, lock_prof_init, NULL);
240 
241 static void
242 lock_prof_reset_wait(void)
243 {
244 
245 	/*
246 	 * Spin relinquishing our cpu so that quiesce_all_cpus may
247 	 * complete.
248 	 */
249 	while (lock_prof_resetting)
250 		sched_relinquish(curthread);
251 }
252 
253 static void
254 lock_prof_reset(void)
255 {
256 	struct lock_prof_cpu *lpc;
257 	int enabled, i, cpu;
258 
259 	/*
260 	 * We not only race with acquiring and releasing locks but also
261 	 * thread exit.  To be certain that threads exit without valid head
262 	 * pointers they must see resetting set before enabled is cleared.
263 	 * Otherwise a lock may not be removed from a per-thread list due
264 	 * to disabled being set but not wait for reset() to remove it below.
265 	 */
266 	atomic_store_rel_int(&lock_prof_resetting, 1);
267 	enabled = lock_prof_enable;
268 	lock_prof_enable = 0;
269 	quiesce_all_cpus("profreset", 0);
270 	/*
271 	 * Some objects may have migrated between CPUs.  Clear all links
272 	 * before we zero the structures.  Some items may still be linked
273 	 * into per-thread lists as well.
274 	 */
275 	for (cpu = 0; cpu <= mp_maxid; cpu++) {
276 		lpc = lp_cpu[cpu];
277 		for (i = 0; i < LPROF_CACHE_SIZE; i++) {
278 			LIST_REMOVE(&lpc->lpc_types[0].lpt_objs[i], lpo_link);
279 			LIST_REMOVE(&lpc->lpc_types[1].lpt_objs[i], lpo_link);
280 		}
281 	}
282 	for (cpu = 0; cpu <= mp_maxid; cpu++) {
283 		lpc = lp_cpu[cpu];
284 		bzero(lpc, sizeof(*lpc));
285 		lock_prof_init_type(&lpc->lpc_types[0]);
286 		lock_prof_init_type(&lpc->lpc_types[1]);
287 	}
288 	atomic_store_rel_int(&lock_prof_resetting, 0);
289 	lock_prof_enable = enabled;
290 }
291 
292 static void
293 lock_prof_output(struct lock_prof *lp, struct sbuf *sb)
294 {
295 	const char *p;
296 
297 	for (p = lp->file; p != NULL && strncmp(p, "../", 3) == 0; p += 3);
298 	sbuf_printf(sb,
299 	    "%8ju %9ju %11ju %11ju %11ju %6ju %6ju %2ju %6ju %s:%d (%s:%s)\n",
300 	    lp->cnt_max / 1000, lp->cnt_wait_max / 1000, lp->cnt_tot / 1000,
301 	    lp->cnt_wait / 1000, lp->cnt_cur,
302 	    lp->cnt_cur == 0 ? (uintmax_t)0 :
303 	    lp->cnt_tot / (lp->cnt_cur * 1000),
304 	    lp->cnt_cur == 0 ? (uintmax_t)0 :
305 	    lp->cnt_wait / (lp->cnt_cur * 1000),
306 	    (uintmax_t)0, lp->cnt_contest_locking,
307 	    p, lp->line, lp->class->lc_name, lp->name);
308 }
309 
310 static void
311 lock_prof_sum(struct lock_prof *match, struct lock_prof *dst, int hash,
312     int spin, int t)
313 {
314 	struct lock_prof_type *type;
315 	struct lock_prof *l;
316 	int cpu;
317 
318 	dst->file = match->file;
319 	dst->line = match->line;
320 	dst->class = match->class;
321 	dst->name = match->name;
322 
323 	for (cpu = 0; cpu <= mp_maxid; cpu++) {
324 		if (lp_cpu[cpu] == NULL)
325 			continue;
326 		type = &lp_cpu[cpu]->lpc_types[spin];
327 		SLIST_FOREACH(l, &type->lpt_hash[hash], link) {
328 			if (l->ticks == t)
329 				continue;
330 			if (l->file != match->file || l->line != match->line ||
331 			    l->name != match->name)
332 				continue;
333 			l->ticks = t;
334 			if (l->cnt_max > dst->cnt_max)
335 				dst->cnt_max = l->cnt_max;
336 			if (l->cnt_wait_max > dst->cnt_wait_max)
337 				dst->cnt_wait_max = l->cnt_wait_max;
338 			dst->cnt_tot += l->cnt_tot;
339 			dst->cnt_wait += l->cnt_wait;
340 			dst->cnt_cur += l->cnt_cur;
341 			dst->cnt_contest_locking += l->cnt_contest_locking;
342 		}
343 	}
344 
345 }
346 
347 static void
348 lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin,
349     int t)
350 {
351 	struct lock_prof *l;
352 	int i;
353 
354 	for (i = 0; i < LPROF_HASH_SIZE; ++i) {
355 		SLIST_FOREACH(l, &type->lpt_hash[i], link) {
356 			struct lock_prof lp = {};
357 
358 			if (l->ticks == t)
359 				continue;
360 			lock_prof_sum(l, &lp, i, spin, t);
361 			lock_prof_output(&lp, sb);
362 		}
363 	}
364 }
365 
366 static int
367 dump_lock_prof_stats(SYSCTL_HANDLER_ARGS)
368 {
369 	struct sbuf *sb;
370 	int error, cpu, t;
371 	int enabled;
372 
373 	error = sysctl_wire_old_buffer(req, 0);
374 	if (error != 0)
375 		return (error);
376 	sb = sbuf_new_for_sysctl(NULL, NULL, LPROF_SBUF_SIZE, req);
377 	sbuf_printf(sb, "\n%8s %9s %11s %11s %11s %6s %6s %2s %6s %s\n",
378 	    "max", "wait_max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name");
379 	enabled = lock_prof_enable;
380 	lock_prof_enable = 0;
381 	quiesce_all_cpus("profstat", 0);
382 	t = ticks;
383 	for (cpu = 0; cpu <= mp_maxid; cpu++) {
384 		if (lp_cpu[cpu] == NULL)
385 			continue;
386 		lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[0], sb, 0, t);
387 		lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[1], sb, 1, t);
388 	}
389 	lock_prof_enable = enabled;
390 
391 	error = sbuf_finish(sb);
392 	/* Output a trailing NUL. */
393 	if (error == 0)
394 		error = SYSCTL_OUT(req, "", 1);
395 	sbuf_delete(sb);
396 	return (error);
397 }
398 
399 static int
400 enable_lock_prof(SYSCTL_HANDLER_ARGS)
401 {
402 	int error, v;
403 
404 	v = lock_prof_enable;
405 	error = sysctl_handle_int(oidp, &v, v, req);
406 	if (error)
407 		return (error);
408 	if (req->newptr == NULL)
409 		return (error);
410 	if (v == lock_prof_enable)
411 		return (0);
412 	if (v == 1)
413 		lock_prof_reset();
414 	lock_prof_enable = !!v;
415 
416 	return (0);
417 }
418 
419 static int
420 reset_lock_prof_stats(SYSCTL_HANDLER_ARGS)
421 {
422 	int error, v;
423 
424 	v = 0;
425 	error = sysctl_handle_int(oidp, &v, 0, req);
426 	if (error)
427 		return (error);
428 	if (req->newptr == NULL)
429 		return (error);
430 	if (v == 0)
431 		return (0);
432 	lock_prof_reset();
433 
434 	return (0);
435 }
436 
437 static struct lock_prof *
438 lock_profile_lookup(struct lock_object *lo, int spin, const char *file,
439     int line)
440 {
441 	const char *unknown = "(unknown)";
442 	struct lock_prof_type *type;
443 	struct lock_prof *lp;
444 	struct lphead *head;
445 	const char *p;
446 	u_int hash;
447 
448 	p = file;
449 	if (p == NULL || *p == '\0')
450 		p = unknown;
451 	hash = (uintptr_t)lo->lo_name * 31 + (uintptr_t)p * 31 + line;
452 	hash &= LPROF_HASH_MASK;
453 	type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
454 	head = &type->lpt_hash[hash];
455 	SLIST_FOREACH(lp, head, link) {
456 		if (lp->line == line && lp->file == p &&
457 		    lp->name == lo->lo_name)
458 			return (lp);
459 
460 	}
461 	lp = SLIST_FIRST(&type->lpt_lpalloc);
462 	if (lp == NULL) {
463 		lock_prof_rejected++;
464 		return (lp);
465 	}
466 	SLIST_REMOVE_HEAD(&type->lpt_lpalloc, link);
467 	lp->file = p;
468 	lp->line = line;
469 	lp->class = LOCK_CLASS(lo);
470 	lp->name = lo->lo_name;
471 	SLIST_INSERT_HEAD(&type->lpt_hash[hash], lp, link);
472 	return (lp);
473 }
474 
475 static struct lock_profile_object *
476 lock_profile_object_lookup(struct lock_object *lo, int spin, const char *file,
477     int line)
478 {
479 	struct lock_profile_object *l;
480 	struct lock_prof_type *type;
481 	struct lpohead *head;
482 
483 	head = &curthread->td_lprof[spin];
484 	LIST_FOREACH(l, head, lpo_link)
485 		if (l->lpo_obj == lo && l->lpo_file == file &&
486 		    l->lpo_line == line)
487 			return (l);
488 	type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
489 	l = LIST_FIRST(&type->lpt_lpoalloc);
490 	if (l == NULL) {
491 		lock_prof_rejected++;
492 		return (NULL);
493 	}
494 	LIST_REMOVE(l, lpo_link);
495 	l->lpo_obj = lo;
496 	l->lpo_file = file;
497 	l->lpo_line = line;
498 	l->lpo_cnt = 0;
499 	LIST_INSERT_HEAD(head, l, lpo_link);
500 
501 	return (l);
502 }
503 
504 void
505 lock_profile_obtain_lock_success(struct lock_object *lo, int contested,
506     uint64_t waittime, const char *file, int line)
507 {
508 	static int lock_prof_count;
509 	struct lock_profile_object *l;
510 	int spin;
511 
512 	if (SCHEDULER_STOPPED())
513 		return;
514 
515 	/* don't reset the timer when/if recursing */
516 	if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE))
517 		return;
518 	if (lock_prof_skipcount &&
519 	    (++lock_prof_count % lock_prof_skipcount) != 0)
520 		return;
521 	spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0;
522 	if (spin && lock_prof_skipspin == 1)
523 		return;
524 	critical_enter();
525 	/* Recheck enabled now that we're in a critical section. */
526 	if (lock_prof_enable == 0)
527 		goto out;
528 	l = lock_profile_object_lookup(lo, spin, file, line);
529 	if (l == NULL)
530 		goto out;
531 	l->lpo_cnt++;
532 	if (++l->lpo_ref > 1)
533 		goto out;
534 	l->lpo_contest_locking = contested;
535 	l->lpo_acqtime = nanoseconds();
536 	if (waittime && (l->lpo_acqtime > waittime))
537 		l->lpo_waittime = l->lpo_acqtime - waittime;
538 	else
539 		l->lpo_waittime = 0;
540 out:
541 	critical_exit();
542 }
543 
544 void
545 lock_profile_thread_exit(struct thread *td)
546 {
547 #ifdef INVARIANTS
548 	struct lock_profile_object *l;
549 
550 	MPASS(curthread->td_critnest == 0);
551 #endif
552 	/*
553 	 * If lock profiling was disabled we have to wait for reset to
554 	 * clear our pointers before we can exit safely.
555 	 */
556 	lock_prof_reset_wait();
557 #ifdef INVARIANTS
558 	LIST_FOREACH(l, &td->td_lprof[0], lpo_link)
559 		printf("thread still holds lock acquired at %s:%d\n",
560 		    l->lpo_file, l->lpo_line);
561 	LIST_FOREACH(l, &td->td_lprof[1], lpo_link)
562 		printf("thread still holds lock acquired at %s:%d\n",
563 		    l->lpo_file, l->lpo_line);
564 #endif
565 	MPASS(LIST_FIRST(&td->td_lprof[0]) == NULL);
566 	MPASS(LIST_FIRST(&td->td_lprof[1]) == NULL);
567 }
568 
569 void
570 lock_profile_release_lock(struct lock_object *lo)
571 {
572 	struct lock_profile_object *l;
573 	struct lock_prof_type *type;
574 	struct lock_prof *lp;
575 	uint64_t curtime, holdtime;
576 	struct lpohead *head;
577 	int spin;
578 
579 	if (SCHEDULER_STOPPED())
580 		return;
581 	if (lo->lo_flags & LO_NOPROFILE)
582 		return;
583 	spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0;
584 	head = &curthread->td_lprof[spin];
585 	if (LIST_FIRST(head) == NULL)
586 		return;
587 	critical_enter();
588 	/* Recheck enabled now that we're in a critical section. */
589 	if (lock_prof_enable == 0 && lock_prof_resetting == 1)
590 		goto out;
591 	/*
592 	 * If lock profiling is not enabled we still want to remove the
593 	 * lpo from our queue.
594 	 */
595 	LIST_FOREACH(l, head, lpo_link)
596 		if (l->lpo_obj == lo)
597 			break;
598 	if (l == NULL)
599 		goto out;
600 	if (--l->lpo_ref > 0)
601 		goto out;
602 	lp = lock_profile_lookup(lo, spin, l->lpo_file, l->lpo_line);
603 	if (lp == NULL)
604 		goto release;
605 	curtime = nanoseconds();
606 	if (curtime < l->lpo_acqtime)
607 		goto release;
608 	holdtime = curtime - l->lpo_acqtime;
609 
610 	/*
611 	 * Record if the lock has been held longer now than ever
612 	 * before.
613 	 */
614 	if (holdtime > lp->cnt_max)
615 		lp->cnt_max = holdtime;
616 	if (l->lpo_waittime > lp->cnt_wait_max)
617 		lp->cnt_wait_max = l->lpo_waittime;
618 	lp->cnt_tot += holdtime;
619 	lp->cnt_wait += l->lpo_waittime;
620 	lp->cnt_contest_locking += l->lpo_contest_locking;
621 	lp->cnt_cur += l->lpo_cnt;
622 release:
623 	LIST_REMOVE(l, lpo_link);
624 	type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
625 	LIST_INSERT_HEAD(&type->lpt_lpoalloc, l, lpo_link);
626 out:
627 	critical_exit();
628 }
629 
630 static SYSCTL_NODE(_debug, OID_AUTO, lock, CTLFLAG_RD, NULL, "lock debugging");
631 static SYSCTL_NODE(_debug_lock, OID_AUTO, prof, CTLFLAG_RD, NULL,
632     "lock profiling");
633 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW,
634     &lock_prof_skipspin, 0, "Skip profiling on spinlocks.");
635 SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipcount, CTLFLAG_RW,
636     &lock_prof_skipcount, 0, "Sample approximately every N lock acquisitions.");
637 SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD,
638     &lock_prof_rejected, 0, "Number of rejected profiling records");
639 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD,
640     NULL, 0, dump_lock_prof_stats, "A", "Lock profiling statistics");
641 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW,
642     NULL, 0, reset_lock_prof_stats, "I", "Reset lock profiling statistics");
643 SYSCTL_PROC(_debug_lock_prof, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW,
644     NULL, 0, enable_lock_prof, "I", "Enable lock profiling");
645 
646 #endif
647