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: stable/10/sys/kern/subr_lock.c 323870 2017-09-21 19:24:11Z marius $");
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#include <machine/cpu.h>
59
60CTASSERT(LOCK_CLASS_MAX == 15);
61
62struct lock_class *lock_classes[LOCK_CLASS_MAX + 1] = {
63	&lock_class_mtx_spin,
64	&lock_class_mtx_sleep,
65	&lock_class_sx,
66	&lock_class_rm,
67	&lock_class_rm_sleepable,
68	&lock_class_rw,
69	&lock_class_lockmgr,
70};
71
72void
73lock_init(struct lock_object *lock, struct lock_class *class, const char *name,
74    const char *type, int flags)
75{
76	int i;
77
78	/* Check for double-init and zero object. */
79	KASSERT(flags & LO_NEW || !lock_initalized(lock),
80	    ("lock \"%s\" %p already initialized", name, lock));
81
82	/* Look up lock class to find its index. */
83	for (i = 0; i < LOCK_CLASS_MAX; i++)
84		if (lock_classes[i] == class) {
85			lock->lo_flags = i << LO_CLASSSHIFT;
86			break;
87		}
88	KASSERT(i < LOCK_CLASS_MAX, ("unknown lock class %p", class));
89
90	/* Initialize the lock object. */
91	lock->lo_name = name;
92	lock->lo_flags |= flags | LO_INITIALIZED;
93	LOCK_LOG_INIT(lock, 0);
94	WITNESS_INIT(lock, (type != NULL) ? type : name);
95}
96
97void
98lock_destroy(struct lock_object *lock)
99{
100
101	KASSERT(lock_initalized(lock), ("lock %p is not initialized", lock));
102	WITNESS_DESTROY(lock);
103	LOCK_LOG_DESTROY(lock, 0);
104	lock->lo_flags &= ~LO_INITIALIZED;
105}
106
107void
108lock_delay(struct lock_delay_arg *la)
109{
110	u_int i, delay, backoff, min, max;
111	struct lock_delay_config *lc = la->config;
112
113	delay = la->delay;
114
115	if (delay == 0)
116		delay = lc->initial;
117	else {
118		delay += lc->step;
119		max = lc->max;
120		if (delay > max)
121			delay = max;
122	}
123
124	backoff = cpu_ticks() % delay;
125	min = lc->min;
126	if (backoff < min)
127		backoff = min;
128	for (i = 0; i < backoff; i++)
129		cpu_spinwait();
130
131	la->delay = delay;
132	la->spin_cnt += backoff;
133}
134
135#ifdef DDB
136DB_SHOW_COMMAND(lock, db_show_lock)
137{
138	struct lock_object *lock;
139	struct lock_class *class;
140
141	if (!have_addr)
142		return;
143	lock = (struct lock_object *)addr;
144	if (LO_CLASSINDEX(lock) > LOCK_CLASS_MAX) {
145		db_printf("Unknown lock class: %d\n", LO_CLASSINDEX(lock));
146		return;
147	}
148	class = LOCK_CLASS(lock);
149	db_printf(" class: %s\n", class->lc_name);
150	db_printf(" name: %s\n", lock->lo_name);
151	class->lc_ddb_show(lock);
152}
153#endif
154
155#ifdef LOCK_PROFILING
156
157/*
158 * One object per-thread for each lock the thread owns.  Tracks individual
159 * lock instances.
160 */
161struct lock_profile_object {
162	LIST_ENTRY(lock_profile_object) lpo_link;
163	struct lock_object *lpo_obj;
164	const char	*lpo_file;
165	int		lpo_line;
166	uint16_t	lpo_ref;
167	uint16_t	lpo_cnt;
168	uint64_t	lpo_acqtime;
169	uint64_t	lpo_waittime;
170	u_int		lpo_contest_locking;
171};
172
173/*
174 * One lock_prof for each (file, line, lock object) triple.
175 */
176struct lock_prof {
177	SLIST_ENTRY(lock_prof) link;
178	struct lock_class *class;
179	const char	*file;
180	const char	*name;
181	int		line;
182	int		ticks;
183	uintmax_t	cnt_wait_max;
184	uintmax_t	cnt_max;
185	uintmax_t	cnt_tot;
186	uintmax_t	cnt_wait;
187	uintmax_t	cnt_cur;
188	uintmax_t	cnt_contest_locking;
189};
190
191SLIST_HEAD(lphead, lock_prof);
192
193#define	LPROF_HASH_SIZE		4096
194#define	LPROF_HASH_MASK		(LPROF_HASH_SIZE - 1)
195#define	LPROF_CACHE_SIZE	4096
196
197/*
198 * Array of objects and profs for each type of object for each cpu.  Spinlocks
199 * are handled separately because a thread may be preempted and acquire a
200 * spinlock while in the lock profiling code of a non-spinlock.  In this way
201 * we only need a critical section to protect the per-cpu lists.
202 */
203struct lock_prof_type {
204	struct lphead		lpt_lpalloc;
205	struct lpohead		lpt_lpoalloc;
206	struct lphead		lpt_hash[LPROF_HASH_SIZE];
207	struct lock_prof	lpt_prof[LPROF_CACHE_SIZE];
208	struct lock_profile_object lpt_objs[LPROF_CACHE_SIZE];
209};
210
211struct lock_prof_cpu {
212	struct lock_prof_type	lpc_types[2]; /* One for spin one for other. */
213};
214
215struct lock_prof_cpu *lp_cpu[MAXCPU];
216
217volatile int lock_prof_enable = 0;
218static volatile int lock_prof_resetting;
219
220#define LPROF_SBUF_SIZE		256
221
222static int lock_prof_rejected;
223static int lock_prof_skipspin;
224static int lock_prof_skipcount;
225
226#ifndef USE_CPU_NANOSECONDS
227uint64_t
228nanoseconds(void)
229{
230	struct bintime bt;
231	uint64_t ns;
232
233	binuptime(&bt);
234	/* From bintime2timespec */
235	ns = bt.sec * (uint64_t)1000000000;
236	ns += ((uint64_t)1000000000 * (uint32_t)(bt.frac >> 32)) >> 32;
237	return (ns);
238}
239#endif
240
241static void
242lock_prof_init_type(struct lock_prof_type *type)
243{
244	int i;
245
246	SLIST_INIT(&type->lpt_lpalloc);
247	LIST_INIT(&type->lpt_lpoalloc);
248	for (i = 0; i < LPROF_CACHE_SIZE; i++) {
249		SLIST_INSERT_HEAD(&type->lpt_lpalloc, &type->lpt_prof[i],
250		    link);
251		LIST_INSERT_HEAD(&type->lpt_lpoalloc, &type->lpt_objs[i],
252		    lpo_link);
253	}
254}
255
256static void
257lock_prof_init(void *arg)
258{
259	int cpu;
260
261	for (cpu = 0; cpu <= mp_maxid; cpu++) {
262		lp_cpu[cpu] = malloc(sizeof(*lp_cpu[cpu]), M_DEVBUF,
263		    M_WAITOK | M_ZERO);
264		lock_prof_init_type(&lp_cpu[cpu]->lpc_types[0]);
265		lock_prof_init_type(&lp_cpu[cpu]->lpc_types[1]);
266	}
267}
268SYSINIT(lockprof, SI_SUB_SMP, SI_ORDER_ANY, lock_prof_init, NULL);
269
270static void
271lock_prof_reset_wait(void)
272{
273
274	/*
275	 * Spin relinquishing our cpu so that quiesce_all_cpus may
276	 * complete.
277	 */
278	while (lock_prof_resetting)
279		sched_relinquish(curthread);
280}
281
282static void
283lock_prof_reset(void)
284{
285	struct lock_prof_cpu *lpc;
286	int enabled, i, cpu;
287
288	/*
289	 * We not only race with acquiring and releasing locks but also
290	 * thread exit.  To be certain that threads exit without valid head
291	 * pointers they must see resetting set before enabled is cleared.
292	 * Otherwise a lock may not be removed from a per-thread list due
293	 * to disabled being set but not wait for reset() to remove it below.
294	 */
295	atomic_store_rel_int(&lock_prof_resetting, 1);
296	enabled = lock_prof_enable;
297	lock_prof_enable = 0;
298	quiesce_all_cpus("profreset", 0);
299	/*
300	 * Some objects may have migrated between CPUs.  Clear all links
301	 * before we zero the structures.  Some items may still be linked
302	 * into per-thread lists as well.
303	 */
304	for (cpu = 0; cpu <= mp_maxid; cpu++) {
305		lpc = lp_cpu[cpu];
306		for (i = 0; i < LPROF_CACHE_SIZE; i++) {
307			LIST_REMOVE(&lpc->lpc_types[0].lpt_objs[i], lpo_link);
308			LIST_REMOVE(&lpc->lpc_types[1].lpt_objs[i], lpo_link);
309		}
310	}
311	for (cpu = 0; cpu <= mp_maxid; cpu++) {
312		lpc = lp_cpu[cpu];
313		bzero(lpc, sizeof(*lpc));
314		lock_prof_init_type(&lpc->lpc_types[0]);
315		lock_prof_init_type(&lpc->lpc_types[1]);
316	}
317	atomic_store_rel_int(&lock_prof_resetting, 0);
318	lock_prof_enable = enabled;
319}
320
321static void
322lock_prof_output(struct lock_prof *lp, struct sbuf *sb)
323{
324	const char *p;
325
326	for (p = lp->file; p != NULL && strncmp(p, "../", 3) == 0; p += 3);
327	sbuf_printf(sb,
328	    "%8ju %9ju %11ju %11ju %11ju %6ju %6ju %2ju %6ju %s:%d (%s:%s)\n",
329	    lp->cnt_max / 1000, lp->cnt_wait_max / 1000, lp->cnt_tot / 1000,
330	    lp->cnt_wait / 1000, lp->cnt_cur,
331	    lp->cnt_cur == 0 ? (uintmax_t)0 :
332	    lp->cnt_tot / (lp->cnt_cur * 1000),
333	    lp->cnt_cur == 0 ? (uintmax_t)0 :
334	    lp->cnt_wait / (lp->cnt_cur * 1000),
335	    (uintmax_t)0, lp->cnt_contest_locking,
336	    p, lp->line, lp->class->lc_name, lp->name);
337}
338
339static void
340lock_prof_sum(struct lock_prof *match, struct lock_prof *dst, int hash,
341    int spin, int t)
342{
343	struct lock_prof_type *type;
344	struct lock_prof *l;
345	int cpu;
346
347	dst->file = match->file;
348	dst->line = match->line;
349	dst->class = match->class;
350	dst->name = match->name;
351
352	for (cpu = 0; cpu <= mp_maxid; cpu++) {
353		if (lp_cpu[cpu] == NULL)
354			continue;
355		type = &lp_cpu[cpu]->lpc_types[spin];
356		SLIST_FOREACH(l, &type->lpt_hash[hash], link) {
357			if (l->ticks == t)
358				continue;
359			if (l->file != match->file || l->line != match->line ||
360			    l->name != match->name)
361				continue;
362			l->ticks = t;
363			if (l->cnt_max > dst->cnt_max)
364				dst->cnt_max = l->cnt_max;
365			if (l->cnt_wait_max > dst->cnt_wait_max)
366				dst->cnt_wait_max = l->cnt_wait_max;
367			dst->cnt_tot += l->cnt_tot;
368			dst->cnt_wait += l->cnt_wait;
369			dst->cnt_cur += l->cnt_cur;
370			dst->cnt_contest_locking += l->cnt_contest_locking;
371		}
372	}
373
374}
375
376static void
377lock_prof_type_stats(struct lock_prof_type *type, struct sbuf *sb, int spin,
378    int t)
379{
380	struct lock_prof *l;
381	int i;
382
383	for (i = 0; i < LPROF_HASH_SIZE; ++i) {
384		SLIST_FOREACH(l, &type->lpt_hash[i], link) {
385			struct lock_prof lp = {};
386
387			if (l->ticks == t)
388				continue;
389			lock_prof_sum(l, &lp, i, spin, t);
390			lock_prof_output(&lp, sb);
391		}
392	}
393}
394
395static int
396dump_lock_prof_stats(SYSCTL_HANDLER_ARGS)
397{
398	struct sbuf *sb;
399	int error, cpu, t;
400	int enabled;
401
402	error = sysctl_wire_old_buffer(req, 0);
403	if (error != 0)
404		return (error);
405	sb = sbuf_new_for_sysctl(NULL, NULL, LPROF_SBUF_SIZE, req);
406	sbuf_printf(sb, "\n%8s %9s %11s %11s %11s %6s %6s %2s %6s %s\n",
407	    "max", "wait_max", "total", "wait_total", "count", "avg", "wait_avg", "cnt_hold", "cnt_lock", "name");
408	enabled = lock_prof_enable;
409	lock_prof_enable = 0;
410	quiesce_all_cpus("profstat", 0);
411	t = ticks;
412	for (cpu = 0; cpu <= mp_maxid; cpu++) {
413		if (lp_cpu[cpu] == NULL)
414			continue;
415		lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[0], sb, 0, t);
416		lock_prof_type_stats(&lp_cpu[cpu]->lpc_types[1], sb, 1, t);
417	}
418	lock_prof_enable = enabled;
419
420	error = sbuf_finish(sb);
421	/* Output a trailing NUL. */
422	if (error == 0)
423		error = SYSCTL_OUT(req, "", 1);
424	sbuf_delete(sb);
425	return (error);
426}
427
428static int
429enable_lock_prof(SYSCTL_HANDLER_ARGS)
430{
431	int error, v;
432
433	v = lock_prof_enable;
434	error = sysctl_handle_int(oidp, &v, v, req);
435	if (error)
436		return (error);
437	if (req->newptr == NULL)
438		return (error);
439	if (v == lock_prof_enable)
440		return (0);
441	if (v == 1)
442		lock_prof_reset();
443	lock_prof_enable = !!v;
444
445	return (0);
446}
447
448static int
449reset_lock_prof_stats(SYSCTL_HANDLER_ARGS)
450{
451	int error, v;
452
453	v = 0;
454	error = sysctl_handle_int(oidp, &v, 0, req);
455	if (error)
456		return (error);
457	if (req->newptr == NULL)
458		return (error);
459	if (v == 0)
460		return (0);
461	lock_prof_reset();
462
463	return (0);
464}
465
466static struct lock_prof *
467lock_profile_lookup(struct lock_object *lo, int spin, const char *file,
468    int line)
469{
470	const char *unknown = "(unknown)";
471	struct lock_prof_type *type;
472	struct lock_prof *lp;
473	struct lphead *head;
474	const char *p;
475	u_int hash;
476
477	p = file;
478	if (p == NULL || *p == '\0')
479		p = unknown;
480	hash = (uintptr_t)lo->lo_name * 31 + (uintptr_t)p * 31 + line;
481	hash &= LPROF_HASH_MASK;
482	type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
483	head = &type->lpt_hash[hash];
484	SLIST_FOREACH(lp, head, link) {
485		if (lp->line == line && lp->file == p &&
486		    lp->name == lo->lo_name)
487			return (lp);
488
489	}
490	lp = SLIST_FIRST(&type->lpt_lpalloc);
491	if (lp == NULL) {
492		lock_prof_rejected++;
493		return (lp);
494	}
495	SLIST_REMOVE_HEAD(&type->lpt_lpalloc, link);
496	lp->file = p;
497	lp->line = line;
498	lp->class = LOCK_CLASS(lo);
499	lp->name = lo->lo_name;
500	SLIST_INSERT_HEAD(&type->lpt_hash[hash], lp, link);
501	return (lp);
502}
503
504static struct lock_profile_object *
505lock_profile_object_lookup(struct lock_object *lo, int spin, const char *file,
506    int line)
507{
508	struct lock_profile_object *l;
509	struct lock_prof_type *type;
510	struct lpohead *head;
511
512	head = &curthread->td_lprof[spin];
513	LIST_FOREACH(l, head, lpo_link)
514		if (l->lpo_obj == lo && l->lpo_file == file &&
515		    l->lpo_line == line)
516			return (l);
517	type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
518	l = LIST_FIRST(&type->lpt_lpoalloc);
519	if (l == NULL) {
520		lock_prof_rejected++;
521		return (NULL);
522	}
523	LIST_REMOVE(l, lpo_link);
524	l->lpo_obj = lo;
525	l->lpo_file = file;
526	l->lpo_line = line;
527	l->lpo_cnt = 0;
528	LIST_INSERT_HEAD(head, l, lpo_link);
529
530	return (l);
531}
532
533void
534lock_profile_obtain_lock_success(struct lock_object *lo, int contested,
535    uint64_t waittime, const char *file, int line)
536{
537	static int lock_prof_count;
538	struct lock_profile_object *l;
539	int spin;
540
541	if (SCHEDULER_STOPPED())
542		return;
543
544	/* don't reset the timer when/if recursing */
545	if (!lock_prof_enable || (lo->lo_flags & LO_NOPROFILE))
546		return;
547	if (lock_prof_skipcount &&
548	    (++lock_prof_count % lock_prof_skipcount) != 0)
549		return;
550	spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0;
551	if (spin && lock_prof_skipspin == 1)
552		return;
553	critical_enter();
554	/* Recheck enabled now that we're in a critical section. */
555	if (lock_prof_enable == 0)
556		goto out;
557	l = lock_profile_object_lookup(lo, spin, file, line);
558	if (l == NULL)
559		goto out;
560	l->lpo_cnt++;
561	if (++l->lpo_ref > 1)
562		goto out;
563	l->lpo_contest_locking = contested;
564	l->lpo_acqtime = nanoseconds();
565	if (waittime && (l->lpo_acqtime > waittime))
566		l->lpo_waittime = l->lpo_acqtime - waittime;
567	else
568		l->lpo_waittime = 0;
569out:
570	critical_exit();
571}
572
573void
574lock_profile_thread_exit(struct thread *td)
575{
576#ifdef INVARIANTS
577	struct lock_profile_object *l;
578
579	MPASS(curthread->td_critnest == 0);
580#endif
581	/*
582	 * If lock profiling was disabled we have to wait for reset to
583	 * clear our pointers before we can exit safely.
584	 */
585	lock_prof_reset_wait();
586#ifdef INVARIANTS
587	LIST_FOREACH(l, &td->td_lprof[0], lpo_link)
588		printf("thread still holds lock acquired at %s:%d\n",
589		    l->lpo_file, l->lpo_line);
590	LIST_FOREACH(l, &td->td_lprof[1], lpo_link)
591		printf("thread still holds lock acquired at %s:%d\n",
592		    l->lpo_file, l->lpo_line);
593#endif
594	MPASS(LIST_FIRST(&td->td_lprof[0]) == NULL);
595	MPASS(LIST_FIRST(&td->td_lprof[1]) == NULL);
596}
597
598void
599lock_profile_release_lock(struct lock_object *lo)
600{
601	struct lock_profile_object *l;
602	struct lock_prof_type *type;
603	struct lock_prof *lp;
604	uint64_t curtime, holdtime;
605	struct lpohead *head;
606	int spin;
607
608	if (SCHEDULER_STOPPED())
609		return;
610	if (lo->lo_flags & LO_NOPROFILE)
611		return;
612	spin = (LOCK_CLASS(lo)->lc_flags & LC_SPINLOCK) ? 1 : 0;
613	head = &curthread->td_lprof[spin];
614	if (LIST_FIRST(head) == NULL)
615		return;
616	critical_enter();
617	/* Recheck enabled now that we're in a critical section. */
618	if (lock_prof_enable == 0 && lock_prof_resetting == 1)
619		goto out;
620	/*
621	 * If lock profiling is not enabled we still want to remove the
622	 * lpo from our queue.
623	 */
624	LIST_FOREACH(l, head, lpo_link)
625		if (l->lpo_obj == lo)
626			break;
627	if (l == NULL)
628		goto out;
629	if (--l->lpo_ref > 0)
630		goto out;
631	lp = lock_profile_lookup(lo, spin, l->lpo_file, l->lpo_line);
632	if (lp == NULL)
633		goto release;
634	curtime = nanoseconds();
635	if (curtime < l->lpo_acqtime)
636		goto release;
637	holdtime = curtime - l->lpo_acqtime;
638
639	/*
640	 * Record if the lock has been held longer now than ever
641	 * before.
642	 */
643	if (holdtime > lp->cnt_max)
644		lp->cnt_max = holdtime;
645	if (l->lpo_waittime > lp->cnt_wait_max)
646		lp->cnt_wait_max = l->lpo_waittime;
647	lp->cnt_tot += holdtime;
648	lp->cnt_wait += l->lpo_waittime;
649	lp->cnt_contest_locking += l->lpo_contest_locking;
650	lp->cnt_cur += l->lpo_cnt;
651release:
652	LIST_REMOVE(l, lpo_link);
653	type = &lp_cpu[PCPU_GET(cpuid)]->lpc_types[spin];
654	LIST_INSERT_HEAD(&type->lpt_lpoalloc, l, lpo_link);
655out:
656	critical_exit();
657}
658
659static SYSCTL_NODE(_debug, OID_AUTO, lock, CTLFLAG_RD, NULL, "lock debugging");
660static SYSCTL_NODE(_debug_lock, OID_AUTO, prof, CTLFLAG_RD, NULL,
661    "lock profiling");
662SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipspin, CTLFLAG_RW,
663    &lock_prof_skipspin, 0, "Skip profiling on spinlocks.");
664SYSCTL_INT(_debug_lock_prof, OID_AUTO, skipcount, CTLFLAG_RW,
665    &lock_prof_skipcount, 0, "Sample approximately every N lock acquisitions.");
666SYSCTL_INT(_debug_lock_prof, OID_AUTO, rejected, CTLFLAG_RD,
667    &lock_prof_rejected, 0, "Number of rejected profiling records");
668SYSCTL_PROC(_debug_lock_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD,
669    NULL, 0, dump_lock_prof_stats, "A", "Lock profiling statistics");
670SYSCTL_PROC(_debug_lock_prof, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW,
671    NULL, 0, reset_lock_prof_stats, "I", "Reset lock profiling statistics");
672SYSCTL_PROC(_debug_lock_prof, OID_AUTO, enable, CTLTYPE_INT | CTLFLAG_RW,
673    NULL, 0, enable_lock_prof, "I", "Enable lock profiling");
674
675#endif
676