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 $
| 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 * $FreeBSD: head/sys/kern/subr_turnstile.c 104161 2002-09-29 23:28:58Z julian $
| 30 * $FreeBSD: head/sys/kern/subr_turnstile.c 104387 2002-10-02 20:31:47Z jhb $
|
31 */
32
33/*
34 * Machine independent bits of mutex implementation.
35 */
36
37#include "opt_adaptive_mutexes.h"
38#include "opt_ddb.h"
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/bus.h>
43#include <sys/kernel.h>
44#include <sys/ktr.h>
45#include <sys/lock.h>
46#include <sys/malloc.h>
47#include <sys/mutex.h>
48#include <sys/proc.h>
49#include <sys/resourcevar.h>
50#include <sys/sbuf.h>
51#include <sys/stdint.h>
52#include <sys/sysctl.h>
53#include <sys/vmmeter.h>
54
55#include <machine/atomic.h>
56#include <machine/bus.h>
57#include <machine/clock.h>
58#include <machine/cpu.h>
59
60#include <ddb/ddb.h>
61
62#include <vm/vm.h>
63#include <vm/vm_extern.h>
64
65/*
66 * Internal utility macros.
67 */
68#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
69
70#define mtx_owner(m) (mtx_unowned((m)) ? NULL \
71 : (struct thread *)((m)->mtx_lock & MTX_FLAGMASK))
72
73/* XXXKSE This test will change. */
74#define thread_running(td) \
75 ((td)->td_kse != NULL && (td)->td_kse->ke_oncpu != NOCPU)
76
77/*
78 * Lock classes for sleep and spin mutexes.
79 */
80struct lock_class lock_class_mtx_sleep = {
81 "sleep mutex",
82 LC_SLEEPLOCK | LC_RECURSABLE
83};
84struct lock_class lock_class_mtx_spin = {
85 "spin mutex",
86 LC_SPINLOCK | LC_RECURSABLE
87};
88
89/*
90 * System-wide mutexes
91 */
92struct mtx sched_lock;
93struct mtx Giant;
94
95/*
96 * Prototypes for non-exported routines.
97 */
98static void propagate_priority(struct thread *);
99
100static void
101propagate_priority(struct thread *td)
102{
103 int pri = td->td_priority;
104 struct mtx *m = td->td_blocked;
105
106 mtx_assert(&sched_lock, MA_OWNED);
107 for (;;) {
108 struct thread *td1;
109
110 td = mtx_owner(m);
111
112 if (td == NULL) {
113 /*
114 * This really isn't quite right. Really
115 * ought to bump priority of thread that
116 * next acquires the mutex.
117 */
118 MPASS(m->mtx_lock == MTX_CONTESTED);
119 return;
120 }
121
122 MPASS(td->td_proc != NULL);
123 MPASS(td->td_proc->p_magic == P_MAGIC);
124 KASSERT(!TD_IS_SLEEPING(td), ("sleeping thread owns a mutex"));
125 if (td->td_priority <= pri) /* lower is higher priority */
126 return;
127
128
129 /*
130 * If lock holder is actually running, just bump priority.
131 */
132 if (TD_IS_RUNNING(td)) {
133 td->td_priority = pri;
134 return;
135 }
136
137#ifndef SMP
138 /*
139 * For UP, we check to see if td is curthread (this shouldn't
140 * ever happen however as it would mean we are in a deadlock.)
141 */
142 KASSERT(td != curthread, ("Deadlock detected"));
143#endif
144
145 /*
146 * If on run queue move to new run queue, and quit.
147 * XXXKSE this gets a lot more complicated under threads
148 * but try anyhow.
149 * We should have a special call to do this more efficiently.
150 */
151 if (TD_ON_RUNQ(td)) {
152 MPASS(td->td_blocked == NULL);
153 remrunqueue(td);
154 td->td_priority = pri;
155 setrunqueue(td);
156 return;
157 }
158 /*
159 * Adjust for any other cases.
160 */
161 td->td_priority = pri;
162
163 /*
164 * If we aren't blocked on a mutex, we should be.
165 */
| 31 */
32
33/*
34 * Machine independent bits of mutex implementation.
35 */
36
37#include "opt_adaptive_mutexes.h"
38#include "opt_ddb.h"
39
40#include <sys/param.h>
41#include <sys/systm.h>
42#include <sys/bus.h>
43#include <sys/kernel.h>
44#include <sys/ktr.h>
45#include <sys/lock.h>
46#include <sys/malloc.h>
47#include <sys/mutex.h>
48#include <sys/proc.h>
49#include <sys/resourcevar.h>
50#include <sys/sbuf.h>
51#include <sys/stdint.h>
52#include <sys/sysctl.h>
53#include <sys/vmmeter.h>
54
55#include <machine/atomic.h>
56#include <machine/bus.h>
57#include <machine/clock.h>
58#include <machine/cpu.h>
59
60#include <ddb/ddb.h>
61
62#include <vm/vm.h>
63#include <vm/vm_extern.h>
64
65/*
66 * Internal utility macros.
67 */
68#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
69
70#define mtx_owner(m) (mtx_unowned((m)) ? NULL \
71 : (struct thread *)((m)->mtx_lock & MTX_FLAGMASK))
72
73/* XXXKSE This test will change. */
74#define thread_running(td) \
75 ((td)->td_kse != NULL && (td)->td_kse->ke_oncpu != NOCPU)
76
77/*
78 * Lock classes for sleep and spin mutexes.
79 */
80struct lock_class lock_class_mtx_sleep = {
81 "sleep mutex",
82 LC_SLEEPLOCK | LC_RECURSABLE
83};
84struct lock_class lock_class_mtx_spin = {
85 "spin mutex",
86 LC_SPINLOCK | LC_RECURSABLE
87};
88
89/*
90 * System-wide mutexes
91 */
92struct mtx sched_lock;
93struct mtx Giant;
94
95/*
96 * Prototypes for non-exported routines.
97 */
98static void propagate_priority(struct thread *);
99
100static void
101propagate_priority(struct thread *td)
102{
103 int pri = td->td_priority;
104 struct mtx *m = td->td_blocked;
105
106 mtx_assert(&sched_lock, MA_OWNED);
107 for (;;) {
108 struct thread *td1;
109
110 td = mtx_owner(m);
111
112 if (td == NULL) {
113 /*
114 * This really isn't quite right. Really
115 * ought to bump priority of thread that
116 * next acquires the mutex.
117 */
118 MPASS(m->mtx_lock == MTX_CONTESTED);
119 return;
120 }
121
122 MPASS(td->td_proc != NULL);
123 MPASS(td->td_proc->p_magic == P_MAGIC);
124 KASSERT(!TD_IS_SLEEPING(td), ("sleeping thread owns a mutex"));
125 if (td->td_priority <= pri) /* lower is higher priority */
126 return;
127
128
129 /*
130 * If lock holder is actually running, just bump priority.
131 */
132 if (TD_IS_RUNNING(td)) {
133 td->td_priority = pri;
134 return;
135 }
136
137#ifndef SMP
138 /*
139 * For UP, we check to see if td is curthread (this shouldn't
140 * ever happen however as it would mean we are in a deadlock.)
141 */
142 KASSERT(td != curthread, ("Deadlock detected"));
143#endif
144
145 /*
146 * If on run queue move to new run queue, and quit.
147 * XXXKSE this gets a lot more complicated under threads
148 * but try anyhow.
149 * We should have a special call to do this more efficiently.
150 */
151 if (TD_ON_RUNQ(td)) {
152 MPASS(td->td_blocked == NULL);
153 remrunqueue(td);
154 td->td_priority = pri;
155 setrunqueue(td);
156 return;
157 }
158 /*
159 * Adjust for any other cases.
160 */
161 td->td_priority = pri;
162
163 /*
164 * If we aren't blocked on a mutex, we should be.
165 */
|
166 KASSERT(TD_ON_MUTEX(td), (
| 166 KASSERT(TD_ON_LOCK(td), (
|
167 "process %d(%s):%d holds %s but isn't blocked on a mutex\n",
168 td->td_proc->p_pid, td->td_proc->p_comm, td->td_state,
169 m->mtx_object.lo_name));
170
171 /*
172 * Pick up the mutex that td is blocked on.
173 */
174 m = td->td_blocked;
175 MPASS(m != NULL);
176
177 /*
178 * Check if the thread needs to be moved up on
179 * the blocked chain
180 */
181 if (td == TAILQ_FIRST(&m->mtx_blocked)) {
182 continue;
183 }
184
| 167 "process %d(%s):%d holds %s but isn't blocked on a mutex\n",
168 td->td_proc->p_pid, td->td_proc->p_comm, td->td_state,
169 m->mtx_object.lo_name));
170
171 /*
172 * Pick up the mutex that td is blocked on.
173 */
174 m = td->td_blocked;
175 MPASS(m != NULL);
176
177 /*
178 * Check if the thread needs to be moved up on
179 * the blocked chain
180 */
181 if (td == TAILQ_FIRST(&m->mtx_blocked)) {
182 continue;
183 }
184
|
185 td1 = TAILQ_PREV(td, threadqueue, td_blkq);
| 185 td1 = TAILQ_PREV(td, threadqueue, td_lockq);
|
186 if (td1->td_priority <= pri) {
187 continue;
188 }
189
190 /*
191 * Remove thread from blocked chain and determine where
192 * it should be moved up to. Since we know that td1 has
193 * a lower priority than td, we know that at least one
194 * thread in the chain has a lower priority and that
195 * td1 will thus not be NULL after the loop.
196 */
| 186 if (td1->td_priority <= pri) {
187 continue;
188 }
189
190 /*
191 * Remove thread from blocked chain and determine where
192 * it should be moved up to. Since we know that td1 has
193 * a lower priority than td, we know that at least one
194 * thread in the chain has a lower priority and that
195 * td1 will thus not be NULL after the loop.
196 */
|
197 TAILQ_REMOVE(&m->mtx_blocked, td, td_blkq);
198 TAILQ_FOREACH(td1, &m->mtx_blocked, td_blkq) {
| 197 TAILQ_REMOVE(&m->mtx_blocked, td, td_lockq);
198 TAILQ_FOREACH(td1, &m->mtx_blocked, td_lockq) {
|
199 MPASS(td1->td_proc->p_magic == P_MAGIC);
200 if (td1->td_priority > pri)
201 break;
202 }
203
204 MPASS(td1 != NULL);
| 199 MPASS(td1->td_proc->p_magic == P_MAGIC);
200 if (td1->td_priority > pri)
201 break;
202 }
203
204 MPASS(td1 != NULL);
|
205 TAILQ_INSERT_BEFORE(td1, td, td_blkq);
| 205 TAILQ_INSERT_BEFORE(td1, td, td_lockq);
|
206 CTR4(KTR_LOCK,
207 "propagate_priority: p %p moved before %p on [%p] %s",
208 td, td1, m, m->mtx_object.lo_name);
209 }
210}
211
212#ifdef MUTEX_PROFILING
213SYSCTL_NODE(_debug, OID_AUTO, mutex, CTLFLAG_RD, NULL, "mutex debugging");
214SYSCTL_NODE(_debug_mutex, OID_AUTO, prof, CTLFLAG_RD, NULL, "mutex profiling");
215static int mutex_prof_enable = 0;
216SYSCTL_INT(_debug_mutex_prof, OID_AUTO, enable, CTLFLAG_RW,
217 &mutex_prof_enable, 0, "Enable tracing of mutex holdtime");
218
219struct mutex_prof {
220 const char *name;
221 const char *file;
222 int line;
223#define MPROF_MAX 0
224#define MPROF_TOT 1
225#define MPROF_CNT 2
226#define MPROF_AVG 3
227 uintmax_t counter[4];
228 struct mutex_prof *next;
229};
230
231/*
232 * mprof_buf is a static pool of profiling records to avoid possible
233 * reentrance of the memory allocation functions.
234 *
235 * Note: NUM_MPROF_BUFFERS must be smaller than MPROF_HASH_SIZE.
236 */
237#define NUM_MPROF_BUFFERS 1000
238static struct mutex_prof mprof_buf[NUM_MPROF_BUFFERS];
239static int first_free_mprof_buf;
240#define MPROF_HASH_SIZE 1009
241static struct mutex_prof *mprof_hash[MPROF_HASH_SIZE];
242
243static int mutex_prof_acquisitions;
244SYSCTL_INT(_debug_mutex_prof, OID_AUTO, acquisitions, CTLFLAG_RD,
245 &mutex_prof_acquisitions, 0, "Number of mutex acquistions recorded");
246static int mutex_prof_records;
247SYSCTL_INT(_debug_mutex_prof, OID_AUTO, records, CTLFLAG_RD,
248 &mutex_prof_records, 0, "Number of profiling records");
249static int mutex_prof_maxrecords = NUM_MPROF_BUFFERS;
250SYSCTL_INT(_debug_mutex_prof, OID_AUTO, maxrecords, CTLFLAG_RD,
251 &mutex_prof_maxrecords, 0, "Maximum number of profiling records");
252static int mutex_prof_rejected;
253SYSCTL_INT(_debug_mutex_prof, OID_AUTO, rejected, CTLFLAG_RD,
254 &mutex_prof_rejected, 0, "Number of rejected profiling records");
255static int mutex_prof_hashsize = MPROF_HASH_SIZE;
256SYSCTL_INT(_debug_mutex_prof, OID_AUTO, hashsize, CTLFLAG_RD,
257 &mutex_prof_hashsize, 0, "Hash size");
258static int mutex_prof_collisions = 0;
259SYSCTL_INT(_debug_mutex_prof, OID_AUTO, collisions, CTLFLAG_RD,
260 &mutex_prof_collisions, 0, "Number of hash collisions");
261
262/*
263 * mprof_mtx protects the profiling buffers and the hash.
264 */
265static struct mtx mprof_mtx;
266MTX_SYSINIT(mprof, &mprof_mtx, "mutex profiling lock", MTX_SPIN | MTX_QUIET);
267
268static u_int64_t
269nanoseconds(void)
270{
271 struct timespec tv;
272
273 nanotime(&tv);
274 return (tv.tv_sec * (u_int64_t)1000000000 + tv.tv_nsec);
275}
276
277static int
278dump_mutex_prof_stats(SYSCTL_HANDLER_ARGS)
279{
280 struct sbuf *sb;
281 int error, i;
282
283 if (first_free_mprof_buf == 0)
284 return SYSCTL_OUT(req, "No locking recorded",
285 sizeof("No locking recorded"));
286
287 sb = sbuf_new(NULL, NULL, 1024, SBUF_AUTOEXTEND);
288 sbuf_printf(sb, "%12s %12s %12s %12s %s\n",
289 "max", "total", "count", "average", "name");
290 mtx_lock_spin(&mprof_mtx);
291 for (i = 0; i < first_free_mprof_buf; ++i)
292 sbuf_printf(sb, "%12ju %12ju %12ju %12ju %s:%d (%s)\n",
293 mprof_buf[i].counter[MPROF_MAX] / 1000,
294 mprof_buf[i].counter[MPROF_TOT] / 1000,
295 mprof_buf[i].counter[MPROF_CNT],
296 mprof_buf[i].counter[MPROF_AVG] / 1000,
297 mprof_buf[i].file, mprof_buf[i].line, mprof_buf[i].name);
298 mtx_unlock_spin(&mprof_mtx);
299 sbuf_finish(sb);
300 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
301 sbuf_delete(sb);
302 return (error);
303}
304SYSCTL_PROC(_debug_mutex_prof, OID_AUTO, stats, CTLTYPE_STRING|CTLFLAG_RD,
305 NULL, 0, dump_mutex_prof_stats, "A", "Mutex profiling statistics");
306#endif
307
308/*
309 * Function versions of the inlined __mtx_* macros. These are used by
310 * modules and can also be called from assembly language if needed.
311 */
312void
313_mtx_lock_flags(struct mtx *m, int opts, const char *file, int line)
314{
315
316 MPASS(curthread != NULL);
317 KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep,
318 ("mtx_lock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
319 file, line));
320 _get_sleep_lock(m, curthread, opts, file, line);
321 LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file,
322 line);
323 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
324#ifdef MUTEX_PROFILING
325 /* don't reset the timer when/if recursing */
326 if (m->mtx_acqtime == 0) {
327 m->mtx_filename = file;
328 m->mtx_lineno = line;
329 m->mtx_acqtime = mutex_prof_enable ? nanoseconds() : 0;
330 ++mutex_prof_acquisitions;
331 }
332#endif
333}
334
335void
336_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line)
337{
338
339 MPASS(curthread != NULL);
340 KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep,
341 ("mtx_unlock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
342 file, line));
343 WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
344 LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file,
345 line);
346 mtx_assert(m, MA_OWNED);
347#ifdef MUTEX_PROFILING
348 if (m->mtx_acqtime != 0) {
349 static const char *unknown = "(unknown)";
350 struct mutex_prof *mpp;
351 u_int64_t acqtime, now;
352 const char *p, *q;
353 volatile u_int hash;
354
355 now = nanoseconds();
356 acqtime = m->mtx_acqtime;
357 m->mtx_acqtime = 0;
358 if (now <= acqtime)
359 goto out;
360 for (p = m->mtx_filename; strncmp(p, "../", 3) == 0; p += 3)
361 /* nothing */ ;
362 if (p == NULL || *p == '\0')
363 p = unknown;
364 for (hash = m->mtx_lineno, q = p; *q != '\0'; ++q)
365 hash = (hash * 2 + *q) % MPROF_HASH_SIZE;
366 mtx_lock_spin(&mprof_mtx);
367 for (mpp = mprof_hash[hash]; mpp != NULL; mpp = mpp->next)
368 if (mpp->line == m->mtx_lineno &&
369 strcmp(mpp->file, p) == 0)
370 break;
371 if (mpp == NULL) {
372 /* Just exit if we cannot get a trace buffer */
373 if (first_free_mprof_buf >= NUM_MPROF_BUFFERS) {
374 ++mutex_prof_rejected;
375 goto unlock;
376 }
377 mpp = &mprof_buf[first_free_mprof_buf++];
378 mpp->name = mtx_name(m);
379 mpp->file = p;
380 mpp->line = m->mtx_lineno;
381 mpp->next = mprof_hash[hash];
382 if (mprof_hash[hash] != NULL)
383 ++mutex_prof_collisions;
384 mprof_hash[hash] = mpp;
385 ++mutex_prof_records;
386 }
387 /*
388 * Record if the mutex has been held longer now than ever
389 * before
390 */
391 if ((now - acqtime) > mpp->counter[MPROF_MAX])
392 mpp->counter[MPROF_MAX] = now - acqtime;
393 mpp->counter[MPROF_TOT] += now - acqtime;
394 mpp->counter[MPROF_CNT] += 1;
395 mpp->counter[MPROF_AVG] =
396 mpp->counter[MPROF_TOT] / mpp->counter[MPROF_CNT];
397unlock:
398 mtx_unlock_spin(&mprof_mtx);
399 }
400out:
401#endif
402 _rel_sleep_lock(m, curthread, opts, file, line);
403}
404
405void
406_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line)
407{
408
409 MPASS(curthread != NULL);
410 KASSERT(m->mtx_object.lo_class == &lock_class_mtx_spin,
411 ("mtx_lock_spin() of sleep mutex %s @ %s:%d",
412 m->mtx_object.lo_name, file, line));
413#if defined(SMP) || LOCK_DEBUG > 0 || 1
414 _get_spin_lock(m, curthread, opts, file, line);
415#else
416 critical_enter();
417#endif
418 LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file,
419 line);
420 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
421}
422
423void
424_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line)
425{
426
427 MPASS(curthread != NULL);
428 KASSERT(m->mtx_object.lo_class == &lock_class_mtx_spin,
429 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
430 m->mtx_object.lo_name, file, line));
431 WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
432 LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file,
433 line);
434 mtx_assert(m, MA_OWNED);
435#if defined(SMP) || LOCK_DEBUG > 0 || 1
436 _rel_spin_lock(m);
437#else
438 critical_exit();
439#endif
440}
441
442/*
443 * The important part of mtx_trylock{,_flags}()
444 * Tries to acquire lock `m.' We do NOT handle recursion here; we assume that
445 * if we're called, it's because we know we don't already own this lock.
446 */
447int
448_mtx_trylock(struct mtx *m, int opts, const char *file, int line)
449{
450 int rval;
451
452 MPASS(curthread != NULL);
453
454 rval = _obtain_lock(m, curthread);
455
456 LOCK_LOG_TRY("LOCK", &m->mtx_object, opts, rval, file, line);
457 if (rval) {
458 /*
459 * We do not handle recursion in _mtx_trylock; see the
460 * note at the top of the routine.
461 */
462 KASSERT(!mtx_recursed(m),
463 ("mtx_trylock() called on a recursed mutex"));
464 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
465 file, line);
466 }
467
468 return (rval);
469}
470
471/*
472 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
473 *
474 * We call this if the lock is either contested (i.e. we need to go to
475 * sleep waiting for it), or if we need to recurse on it.
476 */
477void
478_mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line)
479{
480 struct thread *td = curthread;
481#if defined(SMP) && defined(ADAPTIVE_MUTEXES)
482 struct thread *owner;
483#endif
484#ifdef KTR
485 int cont_logged = 0;
486#endif
487
488 if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)td) {
489 m->mtx_recurse++;
490 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
491 if (LOCK_LOG_TEST(&m->mtx_object, opts))
492 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
493 return;
494 }
495
496 if (LOCK_LOG_TEST(&m->mtx_object, opts))
497 CTR4(KTR_LOCK,
498 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
499 m->mtx_object.lo_name, (void *)m->mtx_lock, file, line);
500
501 while (!_obtain_lock(m, td)) {
502 uintptr_t v;
503 struct thread *td1;
504
505 mtx_lock_spin(&sched_lock);
506 /*
507 * Check if the lock has been released while spinning for
508 * the sched_lock.
509 */
510 if ((v = m->mtx_lock) == MTX_UNOWNED) {
511 mtx_unlock_spin(&sched_lock);
512#ifdef __i386__
513 ia32_pause();
514#endif
515 continue;
516 }
517
518 /*
519 * The mutex was marked contested on release. This means that
520 * there are threads blocked on it.
521 */
522 if (v == MTX_CONTESTED) {
523 td1 = TAILQ_FIRST(&m->mtx_blocked);
524 MPASS(td1 != NULL);
525 m->mtx_lock = (uintptr_t)td | MTX_CONTESTED;
526
527 if (td1->td_priority < td->td_priority)
528 td->td_priority = td1->td_priority;
529 mtx_unlock_spin(&sched_lock);
530 return;
531 }
532
533 /*
534 * If the mutex isn't already contested and a failure occurs
535 * setting the contested bit, the mutex was either released
536 * or the state of the MTX_RECURSED bit changed.
537 */
538 if ((v & MTX_CONTESTED) == 0 &&
539 !atomic_cmpset_ptr(&m->mtx_lock, (void *)v,
540 (void *)(v | MTX_CONTESTED))) {
541 mtx_unlock_spin(&sched_lock);
542#ifdef __i386__
543 ia32_pause();
544#endif
545 continue;
546 }
547
548#if defined(SMP) && defined(ADAPTIVE_MUTEXES)
549 /*
550 * If the current owner of the lock is executing on another
551 * CPU, spin instead of blocking.
552 */
553 owner = (struct thread *)(v & MTX_FLAGMASK);
554 if (m != &Giant && thread_running(owner)) {
555 mtx_unlock_spin(&sched_lock);
556 while (mtx_owner(m) == owner && thread_running(owner)) {
557#ifdef __i386__
558 ia32_pause();
559#endif
560 }
561 continue;
562 }
563#endif /* SMP && ADAPTIVE_MUTEXES */
564
565 /*
566 * We definitely must sleep for this lock.
567 */
568 mtx_assert(m, MA_NOTOWNED);
569
570#ifdef notyet
571 /*
572 * If we're borrowing an interrupted thread's VM context, we
573 * must clean up before going to sleep.
574 */
575 if (td->td_ithd != NULL) {
576 struct ithd *it = td->td_ithd;
577
578 if (it->it_interrupted) {
579 if (LOCK_LOG_TEST(&m->mtx_object, opts))
580 CTR2(KTR_LOCK,
581 "_mtx_lock_sleep: %p interrupted %p",
582 it, it->it_interrupted);
583 intr_thd_fixup(it);
584 }
585 }
586#endif
587
588 /*
589 * Put us on the list of threads blocked on this mutex.
590 */
591 if (TAILQ_EMPTY(&m->mtx_blocked)) {
592 td1 = mtx_owner(m);
593 LIST_INSERT_HEAD(&td1->td_contested, m, mtx_contested);
| 206 CTR4(KTR_LOCK,
207 "propagate_priority: p %p moved before %p on [%p] %s",
208 td, td1, m, m->mtx_object.lo_name);
209 }
210}
211
212#ifdef MUTEX_PROFILING
213SYSCTL_NODE(_debug, OID_AUTO, mutex, CTLFLAG_RD, NULL, "mutex debugging");
214SYSCTL_NODE(_debug_mutex, OID_AUTO, prof, CTLFLAG_RD, NULL, "mutex profiling");
215static int mutex_prof_enable = 0;
216SYSCTL_INT(_debug_mutex_prof, OID_AUTO, enable, CTLFLAG_RW,
217 &mutex_prof_enable, 0, "Enable tracing of mutex holdtime");
218
219struct mutex_prof {
220 const char *name;
221 const char *file;
222 int line;
223#define MPROF_MAX 0
224#define MPROF_TOT 1
225#define MPROF_CNT 2
226#define MPROF_AVG 3
227 uintmax_t counter[4];
228 struct mutex_prof *next;
229};
230
231/*
232 * mprof_buf is a static pool of profiling records to avoid possible
233 * reentrance of the memory allocation functions.
234 *
235 * Note: NUM_MPROF_BUFFERS must be smaller than MPROF_HASH_SIZE.
236 */
237#define NUM_MPROF_BUFFERS 1000
238static struct mutex_prof mprof_buf[NUM_MPROF_BUFFERS];
239static int first_free_mprof_buf;
240#define MPROF_HASH_SIZE 1009
241static struct mutex_prof *mprof_hash[MPROF_HASH_SIZE];
242
243static int mutex_prof_acquisitions;
244SYSCTL_INT(_debug_mutex_prof, OID_AUTO, acquisitions, CTLFLAG_RD,
245 &mutex_prof_acquisitions, 0, "Number of mutex acquistions recorded");
246static int mutex_prof_records;
247SYSCTL_INT(_debug_mutex_prof, OID_AUTO, records, CTLFLAG_RD,
248 &mutex_prof_records, 0, "Number of profiling records");
249static int mutex_prof_maxrecords = NUM_MPROF_BUFFERS;
250SYSCTL_INT(_debug_mutex_prof, OID_AUTO, maxrecords, CTLFLAG_RD,
251 &mutex_prof_maxrecords, 0, "Maximum number of profiling records");
252static int mutex_prof_rejected;
253SYSCTL_INT(_debug_mutex_prof, OID_AUTO, rejected, CTLFLAG_RD,
254 &mutex_prof_rejected, 0, "Number of rejected profiling records");
255static int mutex_prof_hashsize = MPROF_HASH_SIZE;
256SYSCTL_INT(_debug_mutex_prof, OID_AUTO, hashsize, CTLFLAG_RD,
257 &mutex_prof_hashsize, 0, "Hash size");
258static int mutex_prof_collisions = 0;
259SYSCTL_INT(_debug_mutex_prof, OID_AUTO, collisions, CTLFLAG_RD,
260 &mutex_prof_collisions, 0, "Number of hash collisions");
261
262/*
263 * mprof_mtx protects the profiling buffers and the hash.
264 */
265static struct mtx mprof_mtx;
266MTX_SYSINIT(mprof, &mprof_mtx, "mutex profiling lock", MTX_SPIN | MTX_QUIET);
267
268static u_int64_t
269nanoseconds(void)
270{
271 struct timespec tv;
272
273 nanotime(&tv);
274 return (tv.tv_sec * (u_int64_t)1000000000 + tv.tv_nsec);
275}
276
277static int
278dump_mutex_prof_stats(SYSCTL_HANDLER_ARGS)
279{
280 struct sbuf *sb;
281 int error, i;
282
283 if (first_free_mprof_buf == 0)
284 return SYSCTL_OUT(req, "No locking recorded",
285 sizeof("No locking recorded"));
286
287 sb = sbuf_new(NULL, NULL, 1024, SBUF_AUTOEXTEND);
288 sbuf_printf(sb, "%12s %12s %12s %12s %s\n",
289 "max", "total", "count", "average", "name");
290 mtx_lock_spin(&mprof_mtx);
291 for (i = 0; i < first_free_mprof_buf; ++i)
292 sbuf_printf(sb, "%12ju %12ju %12ju %12ju %s:%d (%s)\n",
293 mprof_buf[i].counter[MPROF_MAX] / 1000,
294 mprof_buf[i].counter[MPROF_TOT] / 1000,
295 mprof_buf[i].counter[MPROF_CNT],
296 mprof_buf[i].counter[MPROF_AVG] / 1000,
297 mprof_buf[i].file, mprof_buf[i].line, mprof_buf[i].name);
298 mtx_unlock_spin(&mprof_mtx);
299 sbuf_finish(sb);
300 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
301 sbuf_delete(sb);
302 return (error);
303}
304SYSCTL_PROC(_debug_mutex_prof, OID_AUTO, stats, CTLTYPE_STRING|CTLFLAG_RD,
305 NULL, 0, dump_mutex_prof_stats, "A", "Mutex profiling statistics");
306#endif
307
308/*
309 * Function versions of the inlined __mtx_* macros. These are used by
310 * modules and can also be called from assembly language if needed.
311 */
312void
313_mtx_lock_flags(struct mtx *m, int opts, const char *file, int line)
314{
315
316 MPASS(curthread != NULL);
317 KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep,
318 ("mtx_lock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
319 file, line));
320 _get_sleep_lock(m, curthread, opts, file, line);
321 LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file,
322 line);
323 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
324#ifdef MUTEX_PROFILING
325 /* don't reset the timer when/if recursing */
326 if (m->mtx_acqtime == 0) {
327 m->mtx_filename = file;
328 m->mtx_lineno = line;
329 m->mtx_acqtime = mutex_prof_enable ? nanoseconds() : 0;
330 ++mutex_prof_acquisitions;
331 }
332#endif
333}
334
335void
336_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line)
337{
338
339 MPASS(curthread != NULL);
340 KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep,
341 ("mtx_unlock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
342 file, line));
343 WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
344 LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file,
345 line);
346 mtx_assert(m, MA_OWNED);
347#ifdef MUTEX_PROFILING
348 if (m->mtx_acqtime != 0) {
349 static const char *unknown = "(unknown)";
350 struct mutex_prof *mpp;
351 u_int64_t acqtime, now;
352 const char *p, *q;
353 volatile u_int hash;
354
355 now = nanoseconds();
356 acqtime = m->mtx_acqtime;
357 m->mtx_acqtime = 0;
358 if (now <= acqtime)
359 goto out;
360 for (p = m->mtx_filename; strncmp(p, "../", 3) == 0; p += 3)
361 /* nothing */ ;
362 if (p == NULL || *p == '\0')
363 p = unknown;
364 for (hash = m->mtx_lineno, q = p; *q != '\0'; ++q)
365 hash = (hash * 2 + *q) % MPROF_HASH_SIZE;
366 mtx_lock_spin(&mprof_mtx);
367 for (mpp = mprof_hash[hash]; mpp != NULL; mpp = mpp->next)
368 if (mpp->line == m->mtx_lineno &&
369 strcmp(mpp->file, p) == 0)
370 break;
371 if (mpp == NULL) {
372 /* Just exit if we cannot get a trace buffer */
373 if (first_free_mprof_buf >= NUM_MPROF_BUFFERS) {
374 ++mutex_prof_rejected;
375 goto unlock;
376 }
377 mpp = &mprof_buf[first_free_mprof_buf++];
378 mpp->name = mtx_name(m);
379 mpp->file = p;
380 mpp->line = m->mtx_lineno;
381 mpp->next = mprof_hash[hash];
382 if (mprof_hash[hash] != NULL)
383 ++mutex_prof_collisions;
384 mprof_hash[hash] = mpp;
385 ++mutex_prof_records;
386 }
387 /*
388 * Record if the mutex has been held longer now than ever
389 * before
390 */
391 if ((now - acqtime) > mpp->counter[MPROF_MAX])
392 mpp->counter[MPROF_MAX] = now - acqtime;
393 mpp->counter[MPROF_TOT] += now - acqtime;
394 mpp->counter[MPROF_CNT] += 1;
395 mpp->counter[MPROF_AVG] =
396 mpp->counter[MPROF_TOT] / mpp->counter[MPROF_CNT];
397unlock:
398 mtx_unlock_spin(&mprof_mtx);
399 }
400out:
401#endif
402 _rel_sleep_lock(m, curthread, opts, file, line);
403}
404
405void
406_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line)
407{
408
409 MPASS(curthread != NULL);
410 KASSERT(m->mtx_object.lo_class == &lock_class_mtx_spin,
411 ("mtx_lock_spin() of sleep mutex %s @ %s:%d",
412 m->mtx_object.lo_name, file, line));
413#if defined(SMP) || LOCK_DEBUG > 0 || 1
414 _get_spin_lock(m, curthread, opts, file, line);
415#else
416 critical_enter();
417#endif
418 LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file,
419 line);
420 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
421}
422
423void
424_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line)
425{
426
427 MPASS(curthread != NULL);
428 KASSERT(m->mtx_object.lo_class == &lock_class_mtx_spin,
429 ("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
430 m->mtx_object.lo_name, file, line));
431 WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
432 LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file,
433 line);
434 mtx_assert(m, MA_OWNED);
435#if defined(SMP) || LOCK_DEBUG > 0 || 1
436 _rel_spin_lock(m);
437#else
438 critical_exit();
439#endif
440}
441
442/*
443 * The important part of mtx_trylock{,_flags}()
444 * Tries to acquire lock `m.' We do NOT handle recursion here; we assume that
445 * if we're called, it's because we know we don't already own this lock.
446 */
447int
448_mtx_trylock(struct mtx *m, int opts, const char *file, int line)
449{
450 int rval;
451
452 MPASS(curthread != NULL);
453
454 rval = _obtain_lock(m, curthread);
455
456 LOCK_LOG_TRY("LOCK", &m->mtx_object, opts, rval, file, line);
457 if (rval) {
458 /*
459 * We do not handle recursion in _mtx_trylock; see the
460 * note at the top of the routine.
461 */
462 KASSERT(!mtx_recursed(m),
463 ("mtx_trylock() called on a recursed mutex"));
464 WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
465 file, line);
466 }
467
468 return (rval);
469}
470
471/*
472 * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
473 *
474 * We call this if the lock is either contested (i.e. we need to go to
475 * sleep waiting for it), or if we need to recurse on it.
476 */
477void
478_mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line)
479{
480 struct thread *td = curthread;
481#if defined(SMP) && defined(ADAPTIVE_MUTEXES)
482 struct thread *owner;
483#endif
484#ifdef KTR
485 int cont_logged = 0;
486#endif
487
488 if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)td) {
489 m->mtx_recurse++;
490 atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
491 if (LOCK_LOG_TEST(&m->mtx_object, opts))
492 CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
493 return;
494 }
495
496 if (LOCK_LOG_TEST(&m->mtx_object, opts))
497 CTR4(KTR_LOCK,
498 "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
499 m->mtx_object.lo_name, (void *)m->mtx_lock, file, line);
500
501 while (!_obtain_lock(m, td)) {
502 uintptr_t v;
503 struct thread *td1;
504
505 mtx_lock_spin(&sched_lock);
506 /*
507 * Check if the lock has been released while spinning for
508 * the sched_lock.
509 */
510 if ((v = m->mtx_lock) == MTX_UNOWNED) {
511 mtx_unlock_spin(&sched_lock);
512#ifdef __i386__
513 ia32_pause();
514#endif
515 continue;
516 }
517
518 /*
519 * The mutex was marked contested on release. This means that
520 * there are threads blocked on it.
521 */
522 if (v == MTX_CONTESTED) {
523 td1 = TAILQ_FIRST(&m->mtx_blocked);
524 MPASS(td1 != NULL);
525 m->mtx_lock = (uintptr_t)td | MTX_CONTESTED;
526
527 if (td1->td_priority < td->td_priority)
528 td->td_priority = td1->td_priority;
529 mtx_unlock_spin(&sched_lock);
530 return;
531 }
532
533 /*
534 * If the mutex isn't already contested and a failure occurs
535 * setting the contested bit, the mutex was either released
536 * or the state of the MTX_RECURSED bit changed.
537 */
538 if ((v & MTX_CONTESTED) == 0 &&
539 !atomic_cmpset_ptr(&m->mtx_lock, (void *)v,
540 (void *)(v | MTX_CONTESTED))) {
541 mtx_unlock_spin(&sched_lock);
542#ifdef __i386__
543 ia32_pause();
544#endif
545 continue;
546 }
547
548#if defined(SMP) && defined(ADAPTIVE_MUTEXES)
549 /*
550 * If the current owner of the lock is executing on another
551 * CPU, spin instead of blocking.
552 */
553 owner = (struct thread *)(v & MTX_FLAGMASK);
554 if (m != &Giant && thread_running(owner)) {
555 mtx_unlock_spin(&sched_lock);
556 while (mtx_owner(m) == owner && thread_running(owner)) {
557#ifdef __i386__
558 ia32_pause();
559#endif
560 }
561 continue;
562 }
563#endif /* SMP && ADAPTIVE_MUTEXES */
564
565 /*
566 * We definitely must sleep for this lock.
567 */
568 mtx_assert(m, MA_NOTOWNED);
569
570#ifdef notyet
571 /*
572 * If we're borrowing an interrupted thread's VM context, we
573 * must clean up before going to sleep.
574 */
575 if (td->td_ithd != NULL) {
576 struct ithd *it = td->td_ithd;
577
578 if (it->it_interrupted) {
579 if (LOCK_LOG_TEST(&m->mtx_object, opts))
580 CTR2(KTR_LOCK,
581 "_mtx_lock_sleep: %p interrupted %p",
582 it, it->it_interrupted);
583 intr_thd_fixup(it);
584 }
585 }
586#endif
587
588 /*
589 * Put us on the list of threads blocked on this mutex.
590 */
591 if (TAILQ_EMPTY(&m->mtx_blocked)) {
592 td1 = mtx_owner(m);
593 LIST_INSERT_HEAD(&td1->td_contested, m, mtx_contested);
|
594 TAILQ_INSERT_TAIL(&m->mtx_blocked, td, td_blkq);
| 594 TAILQ_INSERT_TAIL(&m->mtx_blocked, td, td_lockq);
|
595 } else {
| 595 } else {
|
596 TAILQ_FOREACH(td1, &m->mtx_blocked, td_blkq)
| 596 TAILQ_FOREACH(td1, &m->mtx_blocked, td_lockq)
|
597 if (td1->td_priority > td->td_priority)
598 break;
599 if (td1)
| 597 if (td1->td_priority > td->td_priority)
598 break;
599 if (td1)
|
600 TAILQ_INSERT_BEFORE(td1, td, td_blkq);
| 600 TAILQ_INSERT_BEFORE(td1, td, td_lockq);
|
601 else
| 601 else
|
602 TAILQ_INSERT_TAIL(&m->mtx_blocked, td, td_blkq);
| 602 TAILQ_INSERT_TAIL(&m->mtx_blocked, td, td_lockq);
|
603 }
604#ifdef KTR
605 if (!cont_logged) {
606 CTR6(KTR_CONTENTION,
607 "contention: %p at %s:%d wants %s, taken by %s:%d",
608 td, file, line, m->mtx_object.lo_name,
609 WITNESS_FILE(&m->mtx_object),
610 WITNESS_LINE(&m->mtx_object));
611 cont_logged = 1;
612 }
613#endif
614
615 /*
616 * Save who we're blocked on.
617 */
618 td->td_blocked = m;
| 603 }
604#ifdef KTR
605 if (!cont_logged) {
606 CTR6(KTR_CONTENTION,
607 "contention: %p at %s:%d wants %s, taken by %s:%d",
608 td, file, line, m->mtx_object.lo_name,
609 WITNESS_FILE(&m->mtx_object),
610 WITNESS_LINE(&m->mtx_object));
611 cont_logged = 1;
612 }
613#endif
614
615 /*
616 * Save who we're blocked on.
617 */
618 td->td_blocked = m;
|
619 td->td_mtxname = m->mtx_object.lo_name;
620 TD_SET_MUTEX(td);
| 619 td->td_lockname = m->mtx_object.lo_name;
620 TD_SET_LOCK(td);
|
621 propagate_priority(td);
622
623 if (LOCK_LOG_TEST(&m->mtx_object, opts))
624 CTR3(KTR_LOCK,
625 "_mtx_lock_sleep: p %p blocked on [%p] %s", td, m,
626 m->mtx_object.lo_name);
627
628 td->td_proc->p_stats->p_ru.ru_nvcsw++;
629 mi_switch();
630
631 if (LOCK_LOG_TEST(&m->mtx_object, opts))
632 CTR3(KTR_LOCK,
633 "_mtx_lock_sleep: p %p free from blocked on [%p] %s",
634 td, m, m->mtx_object.lo_name);
635
636 mtx_unlock_spin(&sched_lock);
637 }
638
639#ifdef KTR
640 if (cont_logged) {
641 CTR4(KTR_CONTENTION,
642 "contention end: %s acquired by %p at %s:%d",
643 m->mtx_object.lo_name, td, file, line);
644 }
645#endif
646 return;
647}
648
649/*
650 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock.
651 *
652 * This is only called if we need to actually spin for the lock. Recursion
653 * is handled inline.
654 */
655void
656_mtx_lock_spin(struct mtx *m, int opts, const char *file, int line)
657{
658 int i = 0;
659
660 if (LOCK_LOG_TEST(&m->mtx_object, opts))
661 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
662
663 for (;;) {
664 if (_obtain_lock(m, curthread))
665 break;
666
667 /* Give interrupts a chance while we spin. */
668 critical_exit();
669 while (m->mtx_lock != MTX_UNOWNED) {
670 if (i++ < 10000000) {
671#ifdef __i386__
672 ia32_pause();
673#endif
674 continue;
675 }
676 if (i < 60000000)
677 DELAY(1);
678#ifdef DDB
679 else if (!db_active)
680#else
681 else
682#endif
683 panic("spin lock %s held by %p for > 5 seconds",
684 m->mtx_object.lo_name, (void *)m->mtx_lock);
685#ifdef __i386__
686 ia32_pause();
687#endif
688 }
689 critical_enter();
690 }
691
692 if (LOCK_LOG_TEST(&m->mtx_object, opts))
693 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
694
695 return;
696}
697
698/*
699 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
700 *
701 * We are only called here if the lock is recursed or contested (i.e. we
702 * need to wake up a blocked thread).
703 */
704void
705_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line)
706{
707 struct thread *td, *td1;
708 struct mtx *m1;
709 int pri;
710
711 td = curthread;
712
713 if (mtx_recursed(m)) {
714 if (--(m->mtx_recurse) == 0)
715 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
716 if (LOCK_LOG_TEST(&m->mtx_object, opts))
717 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
718 return;
719 }
720
721 mtx_lock_spin(&sched_lock);
722 if (LOCK_LOG_TEST(&m->mtx_object, opts))
723 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
724
725 td1 = TAILQ_FIRST(&m->mtx_blocked);
726#if defined(SMP) && defined(ADAPTIVE_MUTEXES)
727 if (td1 == NULL) {
728 _release_lock_quick(m);
729 if (LOCK_LOG_TEST(&m->mtx_object, opts))
730 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m);
731 mtx_unlock_spin(&sched_lock);
732 return;
733 }
734#endif
735 MPASS(td->td_proc->p_magic == P_MAGIC);
736 MPASS(td1->td_proc->p_magic == P_MAGIC);
737
| 621 propagate_priority(td);
622
623 if (LOCK_LOG_TEST(&m->mtx_object, opts))
624 CTR3(KTR_LOCK,
625 "_mtx_lock_sleep: p %p blocked on [%p] %s", td, m,
626 m->mtx_object.lo_name);
627
628 td->td_proc->p_stats->p_ru.ru_nvcsw++;
629 mi_switch();
630
631 if (LOCK_LOG_TEST(&m->mtx_object, opts))
632 CTR3(KTR_LOCK,
633 "_mtx_lock_sleep: p %p free from blocked on [%p] %s",
634 td, m, m->mtx_object.lo_name);
635
636 mtx_unlock_spin(&sched_lock);
637 }
638
639#ifdef KTR
640 if (cont_logged) {
641 CTR4(KTR_CONTENTION,
642 "contention end: %s acquired by %p at %s:%d",
643 m->mtx_object.lo_name, td, file, line);
644 }
645#endif
646 return;
647}
648
649/*
650 * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock.
651 *
652 * This is only called if we need to actually spin for the lock. Recursion
653 * is handled inline.
654 */
655void
656_mtx_lock_spin(struct mtx *m, int opts, const char *file, int line)
657{
658 int i = 0;
659
660 if (LOCK_LOG_TEST(&m->mtx_object, opts))
661 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
662
663 for (;;) {
664 if (_obtain_lock(m, curthread))
665 break;
666
667 /* Give interrupts a chance while we spin. */
668 critical_exit();
669 while (m->mtx_lock != MTX_UNOWNED) {
670 if (i++ < 10000000) {
671#ifdef __i386__
672 ia32_pause();
673#endif
674 continue;
675 }
676 if (i < 60000000)
677 DELAY(1);
678#ifdef DDB
679 else if (!db_active)
680#else
681 else
682#endif
683 panic("spin lock %s held by %p for > 5 seconds",
684 m->mtx_object.lo_name, (void *)m->mtx_lock);
685#ifdef __i386__
686 ia32_pause();
687#endif
688 }
689 critical_enter();
690 }
691
692 if (LOCK_LOG_TEST(&m->mtx_object, opts))
693 CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
694
695 return;
696}
697
698/*
699 * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
700 *
701 * We are only called here if the lock is recursed or contested (i.e. we
702 * need to wake up a blocked thread).
703 */
704void
705_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line)
706{
707 struct thread *td, *td1;
708 struct mtx *m1;
709 int pri;
710
711 td = curthread;
712
713 if (mtx_recursed(m)) {
714 if (--(m->mtx_recurse) == 0)
715 atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
716 if (LOCK_LOG_TEST(&m->mtx_object, opts))
717 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
718 return;
719 }
720
721 mtx_lock_spin(&sched_lock);
722 if (LOCK_LOG_TEST(&m->mtx_object, opts))
723 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
724
725 td1 = TAILQ_FIRST(&m->mtx_blocked);
726#if defined(SMP) && defined(ADAPTIVE_MUTEXES)
727 if (td1 == NULL) {
728 _release_lock_quick(m);
729 if (LOCK_LOG_TEST(&m->mtx_object, opts))
730 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m);
731 mtx_unlock_spin(&sched_lock);
732 return;
733 }
734#endif
735 MPASS(td->td_proc->p_magic == P_MAGIC);
736 MPASS(td1->td_proc->p_magic == P_MAGIC);
737
|
738 TAILQ_REMOVE(&m->mtx_blocked, td1, td_blkq);
| 738 TAILQ_REMOVE(&m->mtx_blocked, td1, td_lockq);
|
739
740 if (TAILQ_EMPTY(&m->mtx_blocked)) {
741 LIST_REMOVE(m, mtx_contested);
742 _release_lock_quick(m);
743 if (LOCK_LOG_TEST(&m->mtx_object, opts))
744 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m);
745 } else
746 atomic_store_rel_ptr(&m->mtx_lock, (void *)MTX_CONTESTED);
747
748 pri = PRI_MAX;
749 LIST_FOREACH(m1, &td->td_contested, mtx_contested) {
750 int cp = TAILQ_FIRST(&m1->mtx_blocked)->td_priority;
751 if (cp < pri)
752 pri = cp;
753 }
754
755 if (pri > td->td_base_pri)
756 pri = td->td_base_pri;
757 td->td_priority = pri;
758
759 if (LOCK_LOG_TEST(&m->mtx_object, opts))
760 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p contested setrunqueue %p",
761 m, td1);
762
763 td1->td_blocked = NULL;
| 739
740 if (TAILQ_EMPTY(&m->mtx_blocked)) {
741 LIST_REMOVE(m, mtx_contested);
742 _release_lock_quick(m);
743 if (LOCK_LOG_TEST(&m->mtx_object, opts))
744 CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m);
745 } else
746 atomic_store_rel_ptr(&m->mtx_lock, (void *)MTX_CONTESTED);
747
748 pri = PRI_MAX;
749 LIST_FOREACH(m1, &td->td_contested, mtx_contested) {
750 int cp = TAILQ_FIRST(&m1->mtx_blocked)->td_priority;
751 if (cp < pri)
752 pri = cp;
753 }
754
755 if (pri > td->td_base_pri)
756 pri = td->td_base_pri;
757 td->td_priority = pri;
758
759 if (LOCK_LOG_TEST(&m->mtx_object, opts))
760 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p contested setrunqueue %p",
761 m, td1);
762
763 td1->td_blocked = NULL;
|
764 TD_CLR_MUTEX(td1);
| 764 TD_CLR_LOCK(td1);
|
765 if (!TD_CAN_RUN(td1)) {
766 mtx_unlock_spin(&sched_lock);
767 return;
768 }
769 setrunqueue(td1);
770
771 if (td->td_critnest == 1 && td1->td_priority < pri) {
772#ifdef notyet
773 if (td->td_ithd != NULL) {
774 struct ithd *it = td->td_ithd;
775
776 if (it->it_interrupted) {
777 if (LOCK_LOG_TEST(&m->mtx_object, opts))
778 CTR2(KTR_LOCK,
779 "_mtx_unlock_sleep: %p interrupted %p",
780 it, it->it_interrupted);
781 intr_thd_fixup(it);
782 }
783 }
784#endif
785 if (LOCK_LOG_TEST(&m->mtx_object, opts))
786 CTR2(KTR_LOCK,
787 "_mtx_unlock_sleep: %p switching out lock=%p", m,
788 (void *)m->mtx_lock);
789
790 td->td_proc->p_stats->p_ru.ru_nivcsw++;
791 mi_switch();
792 if (LOCK_LOG_TEST(&m->mtx_object, opts))
793 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p",
794 m, (void *)m->mtx_lock);
795 }
796
797 mtx_unlock_spin(&sched_lock);
798
799 return;
800}
801
802/*
803 * All the unlocking of MTX_SPIN locks is done inline.
804 * See the _rel_spin_lock() macro for the details.
805 */
806
807/*
808 * The backing function for the INVARIANTS-enabled mtx_assert()
809 */
810#ifdef INVARIANT_SUPPORT
811void
812_mtx_assert(struct mtx *m, int what, const char *file, int line)
813{
814
815 if (panicstr != NULL)
816 return;
817 switch (what) {
818 case MA_OWNED:
819 case MA_OWNED | MA_RECURSED:
820 case MA_OWNED | MA_NOTRECURSED:
821 if (!mtx_owned(m))
822 panic("mutex %s not owned at %s:%d",
823 m->mtx_object.lo_name, file, line);
824 if (mtx_recursed(m)) {
825 if ((what & MA_NOTRECURSED) != 0)
826 panic("mutex %s recursed at %s:%d",
827 m->mtx_object.lo_name, file, line);
828 } else if ((what & MA_RECURSED) != 0) {
829 panic("mutex %s unrecursed at %s:%d",
830 m->mtx_object.lo_name, file, line);
831 }
832 break;
833 case MA_NOTOWNED:
834 if (mtx_owned(m))
835 panic("mutex %s owned at %s:%d",
836 m->mtx_object.lo_name, file, line);
837 break;
838 default:
839 panic("unknown mtx_assert at %s:%d", file, line);
840 }
841}
842#endif
843
844/*
845 * The MUTEX_DEBUG-enabled mtx_validate()
846 *
847 * Most of these checks have been moved off into the LO_INITIALIZED flag
848 * maintained by the witness code.
849 */
850#ifdef MUTEX_DEBUG
851
852void mtx_validate(struct mtx *);
853
854void
855mtx_validate(struct mtx *m)
856{
857
858/*
859 * XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly
860 * we can re-enable the kernacc() checks.
861 */
862#ifndef __alpha__
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 */
879void
880mtx_sysinit(void *arg)
881{
882 struct mtx_args *margs = arg;
883
884 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts);
885}
886
887/*
888 * Mutex initialization routine; initialize lock `m' of type contained in
889 * `opts' with options contained in `opts' and name `name.' The optional
890 * lock type `type' is used as a general lock category name for use with
891 * witness.
892 */
893void
894mtx_init(struct mtx *m, const char *name, const char *type, int opts)
895{
896 struct lock_object *lock;
897
898 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
899 MTX_SLEEPABLE | MTX_NOWITNESS | MTX_DUPOK)) == 0);
900
901#ifdef MUTEX_DEBUG
902 /* Diagnostic and error correction */
903 mtx_validate(m);
904#endif
905
906 lock = &m->mtx_object;
907 KASSERT((lock->lo_flags & LO_INITIALIZED) == 0,
908 ("mutex %s %p already initialized", name, m));
909 bzero(m, sizeof(*m));
910 if (opts & MTX_SPIN)
911 lock->lo_class = &lock_class_mtx_spin;
912 else
913 lock->lo_class = &lock_class_mtx_sleep;
914 lock->lo_name = name;
915 lock->lo_type = type != NULL ? type : name;
916 if (opts & MTX_QUIET)
917 lock->lo_flags = LO_QUIET;
918 if (opts & MTX_RECURSE)
919 lock->lo_flags |= LO_RECURSABLE;
920 if (opts & MTX_SLEEPABLE)
921 lock->lo_flags |= LO_SLEEPABLE;
922 if ((opts & MTX_NOWITNESS) == 0)
923 lock->lo_flags |= LO_WITNESS;
924 if (opts & MTX_DUPOK)
925 lock->lo_flags |= LO_DUPOK;
926
927 m->mtx_lock = MTX_UNOWNED;
928 TAILQ_INIT(&m->mtx_blocked);
929
930 LOCK_LOG_INIT(lock, opts);
931
932 WITNESS_INIT(lock);
933}
934
935/*
936 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
937 * passed in as a flag here because if the corresponding mtx_init() was
938 * called with MTX_QUIET set, then it will already be set in the mutex's
939 * flags.
940 */
941void
942mtx_destroy(struct mtx *m)
943{
944
945 LOCK_LOG_DESTROY(&m->mtx_object, 0);
946
947 if (!mtx_owned(m))
948 MPASS(mtx_unowned(m));
949 else {
950 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
951
952 /* Tell witness this isn't locked to make it happy. */
953 WITNESS_UNLOCK(&m->mtx_object, LOP_EXCLUSIVE, __FILE__,
954 __LINE__);
955 }
956
957 WITNESS_DESTROY(&m->mtx_object);
958}
959
960/*
961 * Intialize the mutex code and system mutexes. This is called from the MD
962 * startup code prior to mi_startup(). The per-CPU data space needs to be
963 * setup before this is called.
964 */
965void
966mutex_init(void)
967{
968
969 /* Setup thread0 so that mutexes work. */
970 LIST_INIT(&thread0.td_contested);
971
972 /*
973 * Initialize mutexes.
974 */
975 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
976 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE);
977 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
978 mtx_lock(&Giant);
979}
980
981/*
982 * Encapsulated Giant mutex routines. These routines provide encapsulation
983 * control for the Giant mutex, allowing sysctls to be used to turn on and
984 * off Giant around certain subsystems. The default value for the sysctls
985 * are set to what developers believe is stable and working in regards to
986 * the Giant pushdown. Developers should not turn off Giant via these
987 * sysctls unless they know what they are doing.
988 *
989 * Callers of mtx_lock_giant() are expected to pass the return value to an
990 * accompanying mtx_unlock_giant() later on. If multiple subsystems are
991 * effected by a Giant wrap, all related sysctl variables must be zero for
992 * the subsystem call to operate without Giant (as determined by the caller).
993 */
994
995SYSCTL_NODE(_kern, OID_AUTO, giant, CTLFLAG_RD, NULL, "Giant mutex manipulation");
996
997static int kern_giant_all = 0;
998SYSCTL_INT(_kern_giant, OID_AUTO, all, CTLFLAG_RW, &kern_giant_all, 0, "");
999
1000int kern_giant_proc = 1; /* Giant around PROC locks */
1001int kern_giant_file = 1; /* Giant around struct file & filedesc */
1002int kern_giant_ucred = 1; /* Giant around ucred */
1003SYSCTL_INT(_kern_giant, OID_AUTO, proc, CTLFLAG_RW, &kern_giant_proc, 0, "");
1004SYSCTL_INT(_kern_giant, OID_AUTO, file, CTLFLAG_RW, &kern_giant_file, 0, "");
1005SYSCTL_INT(_kern_giant, OID_AUTO, ucred, CTLFLAG_RW, &kern_giant_ucred, 0, "");
1006
1007int
1008mtx_lock_giant(int sysctlvar)
1009{
1010 if (sysctlvar || kern_giant_all) {
1011 mtx_lock(&Giant);
1012 return(1);
1013 }
1014 return(0);
1015}
1016
1017void
1018mtx_unlock_giant(int s)
1019{
1020 if (s)
1021 mtx_unlock(&Giant);
1022}
1023
| 765 if (!TD_CAN_RUN(td1)) {
766 mtx_unlock_spin(&sched_lock);
767 return;
768 }
769 setrunqueue(td1);
770
771 if (td->td_critnest == 1 && td1->td_priority < pri) {
772#ifdef notyet
773 if (td->td_ithd != NULL) {
774 struct ithd *it = td->td_ithd;
775
776 if (it->it_interrupted) {
777 if (LOCK_LOG_TEST(&m->mtx_object, opts))
778 CTR2(KTR_LOCK,
779 "_mtx_unlock_sleep: %p interrupted %p",
780 it, it->it_interrupted);
781 intr_thd_fixup(it);
782 }
783 }
784#endif
785 if (LOCK_LOG_TEST(&m->mtx_object, opts))
786 CTR2(KTR_LOCK,
787 "_mtx_unlock_sleep: %p switching out lock=%p", m,
788 (void *)m->mtx_lock);
789
790 td->td_proc->p_stats->p_ru.ru_nivcsw++;
791 mi_switch();
792 if (LOCK_LOG_TEST(&m->mtx_object, opts))
793 CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p",
794 m, (void *)m->mtx_lock);
795 }
796
797 mtx_unlock_spin(&sched_lock);
798
799 return;
800}
801
802/*
803 * All the unlocking of MTX_SPIN locks is done inline.
804 * See the _rel_spin_lock() macro for the details.
805 */
806
807/*
808 * The backing function for the INVARIANTS-enabled mtx_assert()
809 */
810#ifdef INVARIANT_SUPPORT
811void
812_mtx_assert(struct mtx *m, int what, const char *file, int line)
813{
814
815 if (panicstr != NULL)
816 return;
817 switch (what) {
818 case MA_OWNED:
819 case MA_OWNED | MA_RECURSED:
820 case MA_OWNED | MA_NOTRECURSED:
821 if (!mtx_owned(m))
822 panic("mutex %s not owned at %s:%d",
823 m->mtx_object.lo_name, file, line);
824 if (mtx_recursed(m)) {
825 if ((what & MA_NOTRECURSED) != 0)
826 panic("mutex %s recursed at %s:%d",
827 m->mtx_object.lo_name, file, line);
828 } else if ((what & MA_RECURSED) != 0) {
829 panic("mutex %s unrecursed at %s:%d",
830 m->mtx_object.lo_name, file, line);
831 }
832 break;
833 case MA_NOTOWNED:
834 if (mtx_owned(m))
835 panic("mutex %s owned at %s:%d",
836 m->mtx_object.lo_name, file, line);
837 break;
838 default:
839 panic("unknown mtx_assert at %s:%d", file, line);
840 }
841}
842#endif
843
844/*
845 * The MUTEX_DEBUG-enabled mtx_validate()
846 *
847 * Most of these checks have been moved off into the LO_INITIALIZED flag
848 * maintained by the witness code.
849 */
850#ifdef MUTEX_DEBUG
851
852void mtx_validate(struct mtx *);
853
854void
855mtx_validate(struct mtx *m)
856{
857
858/*
859 * XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly
860 * we can re-enable the kernacc() checks.
861 */
862#ifndef __alpha__
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 */
879void
880mtx_sysinit(void *arg)
881{
882 struct mtx_args *margs = arg;
883
884 mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts);
885}
886
887/*
888 * Mutex initialization routine; initialize lock `m' of type contained in
889 * `opts' with options contained in `opts' and name `name.' The optional
890 * lock type `type' is used as a general lock category name for use with
891 * witness.
892 */
893void
894mtx_init(struct mtx *m, const char *name, const char *type, int opts)
895{
896 struct lock_object *lock;
897
898 MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
899 MTX_SLEEPABLE | MTX_NOWITNESS | MTX_DUPOK)) == 0);
900
901#ifdef MUTEX_DEBUG
902 /* Diagnostic and error correction */
903 mtx_validate(m);
904#endif
905
906 lock = &m->mtx_object;
907 KASSERT((lock->lo_flags & LO_INITIALIZED) == 0,
908 ("mutex %s %p already initialized", name, m));
909 bzero(m, sizeof(*m));
910 if (opts & MTX_SPIN)
911 lock->lo_class = &lock_class_mtx_spin;
912 else
913 lock->lo_class = &lock_class_mtx_sleep;
914 lock->lo_name = name;
915 lock->lo_type = type != NULL ? type : name;
916 if (opts & MTX_QUIET)
917 lock->lo_flags = LO_QUIET;
918 if (opts & MTX_RECURSE)
919 lock->lo_flags |= LO_RECURSABLE;
920 if (opts & MTX_SLEEPABLE)
921 lock->lo_flags |= LO_SLEEPABLE;
922 if ((opts & MTX_NOWITNESS) == 0)
923 lock->lo_flags |= LO_WITNESS;
924 if (opts & MTX_DUPOK)
925 lock->lo_flags |= LO_DUPOK;
926
927 m->mtx_lock = MTX_UNOWNED;
928 TAILQ_INIT(&m->mtx_blocked);
929
930 LOCK_LOG_INIT(lock, opts);
931
932 WITNESS_INIT(lock);
933}
934
935/*
936 * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
937 * passed in as a flag here because if the corresponding mtx_init() was
938 * called with MTX_QUIET set, then it will already be set in the mutex's
939 * flags.
940 */
941void
942mtx_destroy(struct mtx *m)
943{
944
945 LOCK_LOG_DESTROY(&m->mtx_object, 0);
946
947 if (!mtx_owned(m))
948 MPASS(mtx_unowned(m));
949 else {
950 MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
951
952 /* Tell witness this isn't locked to make it happy. */
953 WITNESS_UNLOCK(&m->mtx_object, LOP_EXCLUSIVE, __FILE__,
954 __LINE__);
955 }
956
957 WITNESS_DESTROY(&m->mtx_object);
958}
959
960/*
961 * Intialize the mutex code and system mutexes. This is called from the MD
962 * startup code prior to mi_startup(). The per-CPU data space needs to be
963 * setup before this is called.
964 */
965void
966mutex_init(void)
967{
968
969 /* Setup thread0 so that mutexes work. */
970 LIST_INIT(&thread0.td_contested);
971
972 /*
973 * Initialize mutexes.
974 */
975 mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
976 mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE);
977 mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
978 mtx_lock(&Giant);
979}
980
981/*
982 * Encapsulated Giant mutex routines. These routines provide encapsulation
983 * control for the Giant mutex, allowing sysctls to be used to turn on and
984 * off Giant around certain subsystems. The default value for the sysctls
985 * are set to what developers believe is stable and working in regards to
986 * the Giant pushdown. Developers should not turn off Giant via these
987 * sysctls unless they know what they are doing.
988 *
989 * Callers of mtx_lock_giant() are expected to pass the return value to an
990 * accompanying mtx_unlock_giant() later on. If multiple subsystems are
991 * effected by a Giant wrap, all related sysctl variables must be zero for
992 * the subsystem call to operate without Giant (as determined by the caller).
993 */
994
995SYSCTL_NODE(_kern, OID_AUTO, giant, CTLFLAG_RD, NULL, "Giant mutex manipulation");
996
997static int kern_giant_all = 0;
998SYSCTL_INT(_kern_giant, OID_AUTO, all, CTLFLAG_RW, &kern_giant_all, 0, "");
999
1000int kern_giant_proc = 1; /* Giant around PROC locks */
1001int kern_giant_file = 1; /* Giant around struct file & filedesc */
1002int kern_giant_ucred = 1; /* Giant around ucred */
1003SYSCTL_INT(_kern_giant, OID_AUTO, proc, CTLFLAG_RW, &kern_giant_proc, 0, "");
1004SYSCTL_INT(_kern_giant, OID_AUTO, file, CTLFLAG_RW, &kern_giant_file, 0, "");
1005SYSCTL_INT(_kern_giant, OID_AUTO, ucred, CTLFLAG_RW, &kern_giant_ucred, 0, "");
1006
1007int
1008mtx_lock_giant(int sysctlvar)
1009{
1010 if (sysctlvar || kern_giant_all) {
1011 mtx_lock(&Giant);
1012 return(1);
1013 }
1014 return(0);
1015}
1016
1017void
1018mtx_unlock_giant(int s)
1019{
1020 if (s)
1021 mtx_unlock(&Giant);
1022}
1023
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