1 /*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 2008 Isilon Systems, Inc.
5 * Copyright (c) 2008 Ilya Maykov <ivmaykov@gmail.com>
6 * Copyright (c) 1998 Berkeley Software Design, Inc.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Berkeley Software Design Inc's name may not be used to endorse or
18 * promote products derived from this software without specific prior
19 * written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $
34 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $
35 */
36
37 /*
38 * Implementation of the `witness' lock verifier. Originally implemented for
39 * mutexes in BSD/OS. Extended to handle generic lock objects and lock
40 * classes in FreeBSD.
41 */
42
43 /*
44 * Main Entry: witness
45 * Pronunciation: 'wit-n&s
46 * Function: noun
47 * Etymology: Middle English witnesse, from Old English witnes knowledge,
48 * testimony, witness, from 2wit
49 * Date: before 12th century
50 * 1 : attestation of a fact or event : TESTIMONY
51 * 2 : one that gives evidence; specifically : one who testifies in
52 * a cause or before a judicial tribunal
53 * 3 : one asked to be present at a transaction so as to be able to
54 * testify to its having taken place
55 * 4 : one who has personal knowledge of something
56 * 5 a : something serving as evidence or proof : SIGN
57 * b : public affirmation by word or example of usually
58 * religious faith or conviction <the heroic witness to divine
59 * life -- Pilot>
60 * 6 capitalized : a member of the Jehovah's Witnesses
61 */
62
63 /*
64 * Special rules concerning Giant and lock orders:
65 *
66 * 1) Giant must be acquired before any other mutexes. Stated another way,
67 * no other mutex may be held when Giant is acquired.
68 *
69 * 2) Giant must be released when blocking on a sleepable lock.
70 *
71 * This rule is less obvious, but is a result of Giant providing the same
72 * semantics as spl(). Basically, when a thread sleeps, it must release
73 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule
74 * 2).
75 *
76 * 3) Giant may be acquired before or after sleepable locks.
77 *
78 * This rule is also not quite as obvious. Giant may be acquired after
79 * a sleepable lock because it is a non-sleepable lock and non-sleepable
80 * locks may always be acquired while holding a sleepable lock. The second
81 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose
82 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1
83 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and
84 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to
85 * execute. Thus, acquiring Giant both before and after a sleepable lock
86 * will not result in a lock order reversal.
87 */
88
89 #include <sys/cdefs.h>
90 __FBSDID("$FreeBSD: releng/12.0/sys/kern/subr_witness.c 335356 2018-06-19 01:54:00Z mmacy $");
91
92 #include "opt_ddb.h"
93 #include "opt_hwpmc_hooks.h"
94 #include "opt_stack.h"
95 #include "opt_witness.h"
96
97 #include <sys/param.h>
98 #include <sys/bus.h>
99 #include <sys/kdb.h>
100 #include <sys/kernel.h>
101 #include <sys/ktr.h>
102 #include <sys/lock.h>
103 #include <sys/malloc.h>
104 #include <sys/mutex.h>
105 #include <sys/priv.h>
106 #include <sys/proc.h>
107 #include <sys/sbuf.h>
108 #include <sys/sched.h>
109 #include <sys/stack.h>
110 #include <sys/sysctl.h>
111 #include <sys/syslog.h>
112 #include <sys/systm.h>
113
114 #ifdef DDB
115 #include <ddb/ddb.h>
116 #endif
117
118 #include <machine/stdarg.h>
119
120 #if !defined(DDB) && !defined(STACK)
121 #error "DDB or STACK options are required for WITNESS"
122 #endif
123
124 /* Note that these traces do not work with KTR_ALQ. */
125 #if 0
126 #define KTR_WITNESS KTR_SUBSYS
127 #else
128 #define KTR_WITNESS 0
129 #endif
130
131 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */
132 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */
133 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */
134
135 /* Define this to check for blessed mutexes */
136 #undef BLESSING
137
138 #ifndef WITNESS_COUNT
139 #define WITNESS_COUNT 1536
140 #endif
141 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */
142 #define WITNESS_PENDLIST (512 + (MAXCPU * 4))
143
144 /* Allocate 256 KB of stack data space */
145 #define WITNESS_LO_DATA_COUNT 2048
146
147 /* Prime, gives load factor of ~2 at full load */
148 #define WITNESS_LO_HASH_SIZE 1021
149
150 /*
151 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads
152 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should
153 * probably be safe for the most part, but it's still a SWAG.
154 */
155 #define LOCK_NCHILDREN 5
156 #define LOCK_CHILDCOUNT 2048
157
158 #define MAX_W_NAME 64
159
160 #define FULLGRAPH_SBUF_SIZE 512
161
162 /*
163 * These flags go in the witness relationship matrix and describe the
164 * relationship between any two struct witness objects.
165 */
166 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */
167 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */
168 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */
169 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */
170 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */
171 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR)
172 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT)
173 #define WITNESS_RELATED_MASK \
174 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK)
175 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been
176 * observed. */
177 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */
178 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */
179 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */
180
181 /* Descendant to ancestor flags */
182 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2)
183
184 /* Ancestor to descendant flags */
185 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2)
186
187 #define WITNESS_INDEX_ASSERT(i) \
188 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count)
189
190 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness");
191
192 /*
193 * Lock instances. A lock instance is the data associated with a lock while
194 * it is held by witness. For example, a lock instance will hold the
195 * recursion count of a lock. Lock instances are held in lists. Spin locks
196 * are held in a per-cpu list while sleep locks are held in per-thread list.
197 */
198 struct lock_instance {
199 struct lock_object *li_lock;
200 const char *li_file;
201 int li_line;
202 u_int li_flags;
203 };
204
205 /*
206 * A simple list type used to build the list of locks held by a thread
207 * or CPU. We can't simply embed the list in struct lock_object since a
208 * lock may be held by more than one thread if it is a shared lock. Locks
209 * are added to the head of the list, so we fill up each list entry from
210 * "the back" logically. To ease some of the arithmetic, we actually fill
211 * in each list entry the normal way (children[0] then children[1], etc.) but
212 * when we traverse the list we read children[count-1] as the first entry
213 * down to children[0] as the final entry.
214 */
215 struct lock_list_entry {
216 struct lock_list_entry *ll_next;
217 struct lock_instance ll_children[LOCK_NCHILDREN];
218 u_int ll_count;
219 };
220
221 /*
222 * The main witness structure. One of these per named lock type in the system
223 * (for example, "vnode interlock").
224 */
225 struct witness {
226 char w_name[MAX_W_NAME];
227 uint32_t w_index; /* Index in the relationship matrix */
228 struct lock_class *w_class;
229 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */
230 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */
231 struct witness *w_hash_next; /* Linked list in hash buckets. */
232 const char *w_file; /* File where last acquired */
233 uint32_t w_line; /* Line where last acquired */
234 uint32_t w_refcount;
235 uint16_t w_num_ancestors; /* direct/indirect
236 * ancestor count */
237 uint16_t w_num_descendants; /* direct/indirect
238 * descendant count */
239 int16_t w_ddb_level;
240 unsigned w_displayed:1;
241 unsigned w_reversed:1;
242 };
243
244 STAILQ_HEAD(witness_list, witness);
245
246 /*
247 * The witness hash table. Keys are witness names (const char *), elements are
248 * witness objects (struct witness *).
249 */
250 struct witness_hash {
251 struct witness *wh_array[WITNESS_HASH_SIZE];
252 uint32_t wh_size;
253 uint32_t wh_count;
254 };
255
256 /*
257 * Key type for the lock order data hash table.
258 */
259 struct witness_lock_order_key {
260 uint16_t from;
261 uint16_t to;
262 };
263
264 struct witness_lock_order_data {
265 struct stack wlod_stack;
266 struct witness_lock_order_key wlod_key;
267 struct witness_lock_order_data *wlod_next;
268 };
269
270 /*
271 * The witness lock order data hash table. Keys are witness index tuples
272 * (struct witness_lock_order_key), elements are lock order data objects
273 * (struct witness_lock_order_data).
274 */
275 struct witness_lock_order_hash {
276 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE];
277 u_int wloh_size;
278 u_int wloh_count;
279 };
280
281 #ifdef BLESSING
282 struct witness_blessed {
283 const char *b_lock1;
284 const char *b_lock2;
285 };
286 #endif
287
288 struct witness_pendhelp {
289 const char *wh_type;
290 struct lock_object *wh_lock;
291 };
292
293 struct witness_order_list_entry {
294 const char *w_name;
295 struct lock_class *w_class;
296 };
297
298 /*
299 * Returns 0 if one of the locks is a spin lock and the other is not.
300 * Returns 1 otherwise.
301 */
302 static __inline int
303 witness_lock_type_equal(struct witness *w1, struct witness *w2)
304 {
305
306 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) ==
307 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)));
308 }
309
310 static __inline int
311 witness_lock_order_key_equal(const struct witness_lock_order_key *a,
312 const struct witness_lock_order_key *b)
313 {
314
315 return (a->from == b->from && a->to == b->to);
316 }
317
318 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask,
319 const char *fname);
320 static void adopt(struct witness *parent, struct witness *child);
321 #ifdef BLESSING
322 static int blessed(struct witness *, struct witness *);
323 #endif
324 static void depart(struct witness *w);
325 static struct witness *enroll(const char *description,
326 struct lock_class *lock_class);
327 static struct lock_instance *find_instance(struct lock_list_entry *list,
328 const struct lock_object *lock);
329 static int isitmychild(struct witness *parent, struct witness *child);
330 static int isitmydescendant(struct witness *parent, struct witness *child);
331 static void itismychild(struct witness *parent, struct witness *child);
332 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS);
333 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS);
334 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS);
335 static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS);
336 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent);
337 #ifdef DDB
338 static void witness_ddb_compute_levels(void);
339 static void witness_ddb_display(int(*)(const char *fmt, ...));
340 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...),
341 struct witness *, int indent);
342 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...),
343 struct witness_list *list);
344 static void witness_ddb_level_descendants(struct witness *parent, int l);
345 static void witness_ddb_list(struct thread *td);
346 #endif
347 static void witness_debugger(int cond, const char *msg);
348 static void witness_free(struct witness *m);
349 static struct witness *witness_get(void);
350 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size);
351 static struct witness *witness_hash_get(const char *key);
352 static void witness_hash_put(struct witness *w);
353 static void witness_init_hash_tables(void);
354 static void witness_increment_graph_generation(void);
355 static void witness_lock_list_free(struct lock_list_entry *lle);
356 static struct lock_list_entry *witness_lock_list_get(void);
357 static int witness_lock_order_add(struct witness *parent,
358 struct witness *child);
359 static int witness_lock_order_check(struct witness *parent,
360 struct witness *child);
361 static struct witness_lock_order_data *witness_lock_order_get(
362 struct witness *parent,
363 struct witness *child);
364 static void witness_list_lock(struct lock_instance *instance,
365 int (*prnt)(const char *fmt, ...));
366 static int witness_output(const char *fmt, ...) __printflike(1, 2);
367 static int witness_voutput(const char *fmt, va_list ap) __printflike(1, 0);
368 static void witness_setflag(struct lock_object *lock, int flag, int set);
369
370 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL,
371 "Witness Locking");
372
373 /*
374 * If set to 0, lock order checking is disabled. If set to -1,
375 * witness is completely disabled. Otherwise witness performs full
376 * lock order checking for all locks. At runtime, lock order checking
377 * may be toggled. However, witness cannot be reenabled once it is
378 * completely disabled.
379 */
380 static int witness_watch = 1;
381 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RWTUN | CTLTYPE_INT, NULL, 0,
382 sysctl_debug_witness_watch, "I", "witness is watching lock operations");
383
384 #ifdef KDB
385 /*
386 * When KDB is enabled and witness_kdb is 1, it will cause the system
387 * to drop into kdebug() when:
388 * - a lock hierarchy violation occurs
389 * - locks are held when going to sleep.
390 */
391 #ifdef WITNESS_KDB
392 int witness_kdb = 1;
393 #else
394 int witness_kdb = 0;
395 #endif
396 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, "");
397 #endif /* KDB */
398
399 #if defined(DDB) || defined(KDB)
400 /*
401 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system
402 * to print a stack trace:
403 * - a lock hierarchy violation occurs
404 * - locks are held when going to sleep.
405 */
406 int witness_trace = 1;
407 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, "");
408 #endif /* DDB || KDB */
409
410 #ifdef WITNESS_SKIPSPIN
411 int witness_skipspin = 1;
412 #else
413 int witness_skipspin = 0;
414 #endif
415 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, "");
416
417 int badstack_sbuf_size;
418
419 int witness_count = WITNESS_COUNT;
420 SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN,
421 &witness_count, 0, "");
422
423 /*
424 * Output channel for witness messages. By default we print to the console.
425 */
426 enum witness_channel {
427 WITNESS_CONSOLE,
428 WITNESS_LOG,
429 WITNESS_NONE,
430 };
431
432 static enum witness_channel witness_channel = WITNESS_CONSOLE;
433 SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel, CTLTYPE_STRING |
434 CTLFLAG_RWTUN, NULL, 0, sysctl_debug_witness_channel, "A",
435 "Output channel for warnings");
436
437 /*
438 * Call this to print out the relations between locks.
439 */
440 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD,
441 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs");
442
443 /*
444 * Call this to print out the witness faulty stacks.
445 */
446 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD,
447 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks");
448
449 static struct mtx w_mtx;
450
451 /* w_list */
452 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free);
453 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all);
454
455 /* w_typelist */
456 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin);
457 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep);
458
459 /* lock list */
460 static struct lock_list_entry *w_lock_list_free = NULL;
461 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST];
462 static u_int pending_cnt;
463
464 static int w_free_cnt, w_spin_cnt, w_sleep_cnt;
465 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, "");
466 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, "");
467 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0,
468 "");
469
470 static struct witness *w_data;
471 static uint8_t **w_rmatrix;
472 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT];
473 static struct witness_hash w_hash; /* The witness hash table. */
474
475 /* The lock order data hash */
476 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT];
477 static struct witness_lock_order_data *w_lofree = NULL;
478 static struct witness_lock_order_hash w_lohash;
479 static int w_max_used_index = 0;
480 static unsigned int w_generation = 0;
481 static const char w_notrunning[] = "Witness not running\n";
482 static const char w_stillcold[] = "Witness is still cold\n";
483 #ifdef __i386__
484 static const char w_notallowed[] = "The sysctl is disabled on the arch\n";
485 #endif
486
487 static struct witness_order_list_entry order_lists[] = {
488 /*
489 * sx locks
490 */
491 { "proctree", &lock_class_sx },
492 { "allproc", &lock_class_sx },
493 { "allprison", &lock_class_sx },
494 { NULL, NULL },
495 /*
496 * Various mutexes
497 */
498 { "Giant", &lock_class_mtx_sleep },
499 { "pipe mutex", &lock_class_mtx_sleep },
500 { "sigio lock", &lock_class_mtx_sleep },
501 { "process group", &lock_class_mtx_sleep },
502 #ifdef HWPMC_HOOKS
503 { "pmc-sleep", &lock_class_mtx_sleep },
504 #endif
505 { "process lock", &lock_class_mtx_sleep },
506 { "session", &lock_class_mtx_sleep },
507 { "uidinfo hash", &lock_class_rw },
508 { "time lock", &lock_class_mtx_sleep },
509 { NULL, NULL },
510 /*
511 * umtx
512 */
513 { "umtx lock", &lock_class_mtx_sleep },
514 { NULL, NULL },
515 /*
516 * Sockets
517 */
518 { "accept", &lock_class_mtx_sleep },
519 { "so_snd", &lock_class_mtx_sleep },
520 { "so_rcv", &lock_class_mtx_sleep },
521 { "sellck", &lock_class_mtx_sleep },
522 { NULL, NULL },
523 /*
524 * Routing
525 */
526 { "so_rcv", &lock_class_mtx_sleep },
527 { "radix node head", &lock_class_rm },
528 { "rtentry", &lock_class_mtx_sleep },
529 { "ifaddr", &lock_class_mtx_sleep },
530 { NULL, NULL },
531 /*
532 * IPv4 multicast:
533 * protocol locks before interface locks, after UDP locks.
534 */
535 { "in_multi_sx", &lock_class_sx },
536 { "udpinp", &lock_class_rw },
537 { "in_multi_list_mtx", &lock_class_mtx_sleep },
538 { "igmp_mtx", &lock_class_mtx_sleep },
539 { "ifnet_rw", &lock_class_rw },
540 { "if_addr_lock", &lock_class_mtx_sleep },
541 { NULL, NULL },
542 /*
543 * IPv6 multicast:
544 * protocol locks before interface locks, after UDP locks.
545 */
546 { "in6_multi_sx", &lock_class_sx },
547 { "udpinp", &lock_class_rw },
548 { "in6_multi_list_mtx", &lock_class_mtx_sleep },
549 { "mld_mtx", &lock_class_mtx_sleep },
550 { "ifnet_rw", &lock_class_rw },
551 { "if_addr_lock", &lock_class_mtx_sleep },
552 { NULL, NULL },
553 /*
554 * UNIX Domain Sockets
555 */
556 { "unp_link_rwlock", &lock_class_rw },
557 { "unp_list_lock", &lock_class_mtx_sleep },
558 { "unp", &lock_class_mtx_sleep },
559 { "so_snd", &lock_class_mtx_sleep },
560 { NULL, NULL },
561 /*
562 * UDP/IP
563 */
564 { "udp", &lock_class_mtx_sleep },
565 { "udpinp", &lock_class_rw },
566 { "so_snd", &lock_class_mtx_sleep },
567 { NULL, NULL },
568 /*
569 * TCP/IP
570 */
571 { "tcp", &lock_class_mtx_sleep },
572 { "tcpinp", &lock_class_rw },
573 { "so_snd", &lock_class_mtx_sleep },
574 { NULL, NULL },
575 /*
576 * BPF
577 */
578 { "bpf global lock", &lock_class_sx },
579 { "bpf interface lock", &lock_class_rw },
580 { "bpf cdev lock", &lock_class_mtx_sleep },
581 { NULL, NULL },
582 /*
583 * NFS server
584 */
585 { "nfsd_mtx", &lock_class_mtx_sleep },
586 { "so_snd", &lock_class_mtx_sleep },
587 { NULL, NULL },
588
589 /*
590 * IEEE 802.11
591 */
592 { "802.11 com lock", &lock_class_mtx_sleep},
593 { NULL, NULL },
594 /*
595 * Network drivers
596 */
597 { "network driver", &lock_class_mtx_sleep},
598 { NULL, NULL },
599
600 /*
601 * Netgraph
602 */
603 { "ng_node", &lock_class_mtx_sleep },
604 { "ng_worklist", &lock_class_mtx_sleep },
605 { NULL, NULL },
606 /*
607 * CDEV
608 */
609 { "vm map (system)", &lock_class_mtx_sleep },
610 { "vnode interlock", &lock_class_mtx_sleep },
611 { "cdev", &lock_class_mtx_sleep },
612 { NULL, NULL },
613 /*
614 * VM
615 */
616 { "vm map (user)", &lock_class_sx },
617 { "vm object", &lock_class_rw },
618 { "vm page", &lock_class_mtx_sleep },
619 { "pmap pv global", &lock_class_rw },
620 { "pmap", &lock_class_mtx_sleep },
621 { "pmap pv list", &lock_class_rw },
622 { "vm page free queue", &lock_class_mtx_sleep },
623 { "vm pagequeue", &lock_class_mtx_sleep },
624 { NULL, NULL },
625 /*
626 * kqueue/VFS interaction
627 */
628 { "kqueue", &lock_class_mtx_sleep },
629 { "struct mount mtx", &lock_class_mtx_sleep },
630 { "vnode interlock", &lock_class_mtx_sleep },
631 { NULL, NULL },
632 /*
633 * VFS namecache
634 */
635 { "ncvn", &lock_class_mtx_sleep },
636 { "ncbuc", &lock_class_rw },
637 { "vnode interlock", &lock_class_mtx_sleep },
638 { "ncneg", &lock_class_mtx_sleep },
639 { NULL, NULL },
640 /*
641 * ZFS locking
642 */
643 { "dn->dn_mtx", &lock_class_sx },
644 { "dr->dt.di.dr_mtx", &lock_class_sx },
645 { "db->db_mtx", &lock_class_sx },
646 { NULL, NULL },
647 /*
648 * TCP log locks
649 */
650 { "TCP ID tree", &lock_class_rw },
651 { "tcp log id bucket", &lock_class_mtx_sleep },
652 { "tcpinp", &lock_class_rw },
653 { "TCP log expireq", &lock_class_mtx_sleep },
654 { NULL, NULL },
655 /*
656 * spin locks
657 */
658 #ifdef SMP
659 { "ap boot", &lock_class_mtx_spin },
660 #endif
661 { "rm.mutex_mtx", &lock_class_mtx_spin },
662 { "sio", &lock_class_mtx_spin },
663 #ifdef __i386__
664 { "cy", &lock_class_mtx_spin },
665 #endif
666 #ifdef __sparc64__
667 { "pcib_mtx", &lock_class_mtx_spin },
668 { "rtc_mtx", &lock_class_mtx_spin },
669 #endif
670 { "scc_hwmtx", &lock_class_mtx_spin },
671 { "uart_hwmtx", &lock_class_mtx_spin },
672 { "fast_taskqueue", &lock_class_mtx_spin },
673 { "intr table", &lock_class_mtx_spin },
674 { "process slock", &lock_class_mtx_spin },
675 { "syscons video lock", &lock_class_mtx_spin },
676 { "sleepq chain", &lock_class_mtx_spin },
677 { "rm_spinlock", &lock_class_mtx_spin },
678 { "turnstile chain", &lock_class_mtx_spin },
679 { "turnstile lock", &lock_class_mtx_spin },
680 { "sched lock", &lock_class_mtx_spin },
681 { "td_contested", &lock_class_mtx_spin },
682 { "callout", &lock_class_mtx_spin },
683 { "entropy harvest mutex", &lock_class_mtx_spin },
684 #ifdef SMP
685 { "smp rendezvous", &lock_class_mtx_spin },
686 #endif
687 #ifdef __powerpc__
688 { "tlb0", &lock_class_mtx_spin },
689 #endif
690 { NULL, NULL },
691 { "sched lock", &lock_class_mtx_spin },
692 #ifdef HWPMC_HOOKS
693 { "pmc-per-proc", &lock_class_mtx_spin },
694 #endif
695 { NULL, NULL },
696 /*
697 * leaf locks
698 */
699 { "intrcnt", &lock_class_mtx_spin },
700 { "icu", &lock_class_mtx_spin },
701 #if defined(SMP) && defined(__sparc64__)
702 { "ipi", &lock_class_mtx_spin },
703 #endif
704 #ifdef __i386__
705 { "allpmaps", &lock_class_mtx_spin },
706 { "descriptor tables", &lock_class_mtx_spin },
707 #endif
708 { "clk", &lock_class_mtx_spin },
709 { "cpuset", &lock_class_mtx_spin },
710 { "mprof lock", &lock_class_mtx_spin },
711 { "zombie lock", &lock_class_mtx_spin },
712 { "ALD Queue", &lock_class_mtx_spin },
713 #if defined(__i386__) || defined(__amd64__)
714 { "pcicfg", &lock_class_mtx_spin },
715 { "NDIS thread lock", &lock_class_mtx_spin },
716 #endif
717 { "tw_osl_io_lock", &lock_class_mtx_spin },
718 { "tw_osl_q_lock", &lock_class_mtx_spin },
719 { "tw_cl_io_lock", &lock_class_mtx_spin },
720 { "tw_cl_intr_lock", &lock_class_mtx_spin },
721 { "tw_cl_gen_lock", &lock_class_mtx_spin },
722 #ifdef HWPMC_HOOKS
723 { "pmc-leaf", &lock_class_mtx_spin },
724 #endif
725 { "blocked lock", &lock_class_mtx_spin },
726 { NULL, NULL },
727 { NULL, NULL }
728 };
729
730 #ifdef BLESSING
731 /*
732 * Pairs of locks which have been blessed
733 * Don't complain about order problems with blessed locks
734 */
735 static struct witness_blessed blessed_list[] = {
736 };
737 #endif
738
739 /*
740 * This global is set to 0 once it becomes safe to use the witness code.
741 */
742 static int witness_cold = 1;
743
744 /*
745 * This global is set to 1 once the static lock orders have been enrolled
746 * so that a warning can be issued for any spin locks enrolled later.
747 */
748 static int witness_spin_warn = 0;
749
750 /* Trim useless garbage from filenames. */
751 static const char *
752 fixup_filename(const char *file)
753 {
754
755 if (file == NULL)
756 return (NULL);
757 while (strncmp(file, "../", 3) == 0)
758 file += 3;
759 return (file);
760 }
761
762 /*
763 * Calculate the size of early witness structures.
764 */
765 int
766 witness_startup_count(void)
767 {
768 int sz;
769
770 sz = sizeof(struct witness) * witness_count;
771 sz += sizeof(*w_rmatrix) * (witness_count + 1);
772 sz += sizeof(*w_rmatrix[0]) * (witness_count + 1) *
773 (witness_count + 1);
774
775 return (sz);
776 }
777
778 /*
779 * The WITNESS-enabled diagnostic code. Note that the witness code does
780 * assume that the early boot is single-threaded at least until after this
781 * routine is completed.
782 */
783 void
784 witness_startup(void *mem)
785 {
786 struct lock_object *lock;
787 struct witness_order_list_entry *order;
788 struct witness *w, *w1;
789 uintptr_t p;
790 int i;
791
792 p = (uintptr_t)mem;
793 w_data = (void *)p;
794 p += sizeof(struct witness) * witness_count;
795
796 w_rmatrix = (void *)p;
797 p += sizeof(*w_rmatrix) * (witness_count + 1);
798
799 for (i = 0; i < witness_count + 1; i++) {
800 w_rmatrix[i] = (void *)p;
801 p += sizeof(*w_rmatrix[i]) * (witness_count + 1);
802 }
803 badstack_sbuf_size = witness_count * 256;
804
805 /*
806 * We have to release Giant before initializing its witness
807 * structure so that WITNESS doesn't get confused.
808 */
809 mtx_unlock(&Giant);
810 mtx_assert(&Giant, MA_NOTOWNED);
811
812 CTR1(KTR_WITNESS, "%s: initializing witness", __func__);
813 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET |
814 MTX_NOWITNESS | MTX_NOPROFILE);
815 for (i = witness_count - 1; i >= 0; i--) {
816 w = &w_data[i];
817 memset(w, 0, sizeof(*w));
818 w_data[i].w_index = i; /* Witness index never changes. */
819 witness_free(w);
820 }
821 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0,
822 ("%s: Invalid list of free witness objects", __func__));
823
824 /* Witness with index 0 is not used to aid in debugging. */
825 STAILQ_REMOVE_HEAD(&w_free, w_list);
826 w_free_cnt--;
827
828 for (i = 0; i < witness_count; i++) {
829 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) *
830 (witness_count + 1));
831 }
832
833 for (i = 0; i < LOCK_CHILDCOUNT; i++)
834 witness_lock_list_free(&w_locklistdata[i]);
835 witness_init_hash_tables();
836
837 /* First add in all the specified order lists. */
838 for (order = order_lists; order->w_name != NULL; order++) {
839 w = enroll(order->w_name, order->w_class);
840 if (w == NULL)
841 continue;
842 w->w_file = "order list";
843 for (order++; order->w_name != NULL; order++) {
844 w1 = enroll(order->w_name, order->w_class);
845 if (w1 == NULL)
846 continue;
847 w1->w_file = "order list";
848 itismychild(w, w1);
849 w = w1;
850 }
851 }
852 witness_spin_warn = 1;
853
854 /* Iterate through all locks and add them to witness. */
855 for (i = 0; pending_locks[i].wh_lock != NULL; i++) {
856 lock = pending_locks[i].wh_lock;
857 KASSERT(lock->lo_flags & LO_WITNESS,
858 ("%s: lock %s is on pending list but not LO_WITNESS",
859 __func__, lock->lo_name));
860 lock->lo_witness = enroll(pending_locks[i].wh_type,
861 LOCK_CLASS(lock));
862 }
863
864 /* Mark the witness code as being ready for use. */
865 witness_cold = 0;
866
867 mtx_lock(&Giant);
868 }
869
870 void
871 witness_init(struct lock_object *lock, const char *type)
872 {
873 struct lock_class *class;
874
875 /* Various sanity checks. */
876 class = LOCK_CLASS(lock);
877 if ((lock->lo_flags & LO_RECURSABLE) != 0 &&
878 (class->lc_flags & LC_RECURSABLE) == 0)
879 kassert_panic("%s: lock (%s) %s can not be recursable",
880 __func__, class->lc_name, lock->lo_name);
881 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
882 (class->lc_flags & LC_SLEEPABLE) == 0)
883 kassert_panic("%s: lock (%s) %s can not be sleepable",
884 __func__, class->lc_name, lock->lo_name);
885 if ((lock->lo_flags & LO_UPGRADABLE) != 0 &&
886 (class->lc_flags & LC_UPGRADABLE) == 0)
887 kassert_panic("%s: lock (%s) %s can not be upgradable",
888 __func__, class->lc_name, lock->lo_name);
889
890 /*
891 * If we shouldn't watch this lock, then just clear lo_witness.
892 * Otherwise, if witness_cold is set, then it is too early to
893 * enroll this lock, so defer it to witness_initialize() by adding
894 * it to the pending_locks list. If it is not too early, then enroll
895 * the lock now.
896 */
897 if (witness_watch < 1 || panicstr != NULL ||
898 (lock->lo_flags & LO_WITNESS) == 0)
899 lock->lo_witness = NULL;
900 else if (witness_cold) {
901 pending_locks[pending_cnt].wh_lock = lock;
902 pending_locks[pending_cnt++].wh_type = type;
903 if (pending_cnt > WITNESS_PENDLIST)
904 panic("%s: pending locks list is too small, "
905 "increase WITNESS_PENDLIST\n",
906 __func__);
907 } else
908 lock->lo_witness = enroll(type, class);
909 }
910
911 void
912 witness_destroy(struct lock_object *lock)
913 {
914 struct lock_class *class;
915 struct witness *w;
916
917 class = LOCK_CLASS(lock);
918
919 if (witness_cold)
920 panic("lock (%s) %s destroyed while witness_cold",
921 class->lc_name, lock->lo_name);
922
923 /* XXX: need to verify that no one holds the lock */
924 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL)
925 return;
926 w = lock->lo_witness;
927
928 mtx_lock_spin(&w_mtx);
929 MPASS(w->w_refcount > 0);
930 w->w_refcount--;
931
932 if (w->w_refcount == 0)
933 depart(w);
934 mtx_unlock_spin(&w_mtx);
935 }
936
937 #ifdef DDB
938 static void
939 witness_ddb_compute_levels(void)
940 {
941 struct witness *w;
942
943 /*
944 * First clear all levels.
945 */
946 STAILQ_FOREACH(w, &w_all, w_list)
947 w->w_ddb_level = -1;
948
949 /*
950 * Look for locks with no parents and level all their descendants.
951 */
952 STAILQ_FOREACH(w, &w_all, w_list) {
953
954 /* If the witness has ancestors (is not a root), skip it. */
955 if (w->w_num_ancestors > 0)
956 continue;
957 witness_ddb_level_descendants(w, 0);
958 }
959 }
960
961 static void
962 witness_ddb_level_descendants(struct witness *w, int l)
963 {
964 int i;
965
966 if (w->w_ddb_level >= l)
967 return;
968
969 w->w_ddb_level = l;
970 l++;
971
972 for (i = 1; i <= w_max_used_index; i++) {
973 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT)
974 witness_ddb_level_descendants(&w_data[i], l);
975 }
976 }
977
978 static void
979 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...),
980 struct witness *w, int indent)
981 {
982 int i;
983
984 for (i = 0; i < indent; i++)
985 prnt(" ");
986 prnt("%s (type: %s, depth: %d, active refs: %d)",
987 w->w_name, w->w_class->lc_name,
988 w->w_ddb_level, w->w_refcount);
989 if (w->w_displayed) {
990 prnt(" -- (already displayed)\n");
991 return;
992 }
993 w->w_displayed = 1;
994 if (w->w_file != NULL && w->w_line != 0)
995 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file),
996 w->w_line);
997 else
998 prnt(" -- never acquired\n");
999 indent++;
1000 WITNESS_INDEX_ASSERT(w->w_index);
1001 for (i = 1; i <= w_max_used_index; i++) {
1002 if (db_pager_quit)
1003 return;
1004 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT)
1005 witness_ddb_display_descendants(prnt, &w_data[i],
1006 indent);
1007 }
1008 }
1009
1010 static void
1011 witness_ddb_display_list(int(*prnt)(const char *fmt, ...),
1012 struct witness_list *list)
1013 {
1014 struct witness *w;
1015
1016 STAILQ_FOREACH(w, list, w_typelist) {
1017 if (w->w_file == NULL || w->w_ddb_level > 0)
1018 continue;
1019
1020 /* This lock has no anscestors - display its descendants. */
1021 witness_ddb_display_descendants(prnt, w, 0);
1022 if (db_pager_quit)
1023 return;
1024 }
1025 }
1026
1027 static void
1028 witness_ddb_display(int(*prnt)(const char *fmt, ...))
1029 {
1030 struct witness *w;
1031
1032 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1033 witness_ddb_compute_levels();
1034
1035 /* Clear all the displayed flags. */
1036 STAILQ_FOREACH(w, &w_all, w_list)
1037 w->w_displayed = 0;
1038
1039 /*
1040 * First, handle sleep locks which have been acquired at least
1041 * once.
1042 */
1043 prnt("Sleep locks:\n");
1044 witness_ddb_display_list(prnt, &w_sleep);
1045 if (db_pager_quit)
1046 return;
1047
1048 /*
1049 * Now do spin locks which have been acquired at least once.
1050 */
1051 prnt("\nSpin locks:\n");
1052 witness_ddb_display_list(prnt, &w_spin);
1053 if (db_pager_quit)
1054 return;
1055
1056 /*
1057 * Finally, any locks which have not been acquired yet.
1058 */
1059 prnt("\nLocks which were never acquired:\n");
1060 STAILQ_FOREACH(w, &w_all, w_list) {
1061 if (w->w_file != NULL || w->w_refcount == 0)
1062 continue;
1063 prnt("%s (type: %s, depth: %d)\n", w->w_name,
1064 w->w_class->lc_name, w->w_ddb_level);
1065 if (db_pager_quit)
1066 return;
1067 }
1068 }
1069 #endif /* DDB */
1070
1071 int
1072 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2)
1073 {
1074
1075 if (witness_watch == -1 || panicstr != NULL)
1076 return (0);
1077
1078 /* Require locks that witness knows about. */
1079 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL ||
1080 lock2->lo_witness == NULL)
1081 return (EINVAL);
1082
1083 mtx_assert(&w_mtx, MA_NOTOWNED);
1084 mtx_lock_spin(&w_mtx);
1085
1086 /*
1087 * If we already have either an explicit or implied lock order that
1088 * is the other way around, then return an error.
1089 */
1090 if (witness_watch &&
1091 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) {
1092 mtx_unlock_spin(&w_mtx);
1093 return (EDOOFUS);
1094 }
1095
1096 /* Try to add the new order. */
1097 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
1098 lock2->lo_witness->w_name, lock1->lo_witness->w_name);
1099 itismychild(lock1->lo_witness, lock2->lo_witness);
1100 mtx_unlock_spin(&w_mtx);
1101 return (0);
1102 }
1103
1104 void
1105 witness_checkorder(struct lock_object *lock, int flags, const char *file,
1106 int line, struct lock_object *interlock)
1107 {
1108 struct lock_list_entry *lock_list, *lle;
1109 struct lock_instance *lock1, *lock2, *plock;
1110 struct lock_class *class, *iclass;
1111 struct witness *w, *w1;
1112 struct thread *td;
1113 int i, j;
1114
1115 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL ||
1116 panicstr != NULL)
1117 return;
1118
1119 w = lock->lo_witness;
1120 class = LOCK_CLASS(lock);
1121 td = curthread;
1122
1123 if (class->lc_flags & LC_SLEEPLOCK) {
1124
1125 /*
1126 * Since spin locks include a critical section, this check
1127 * implicitly enforces a lock order of all sleep locks before
1128 * all spin locks.
1129 */
1130 if (td->td_critnest != 0 && !kdb_active)
1131 kassert_panic("acquiring blockable sleep lock with "
1132 "spinlock or critical section held (%s) %s @ %s:%d",
1133 class->lc_name, lock->lo_name,
1134 fixup_filename(file), line);
1135
1136 /*
1137 * If this is the first lock acquired then just return as
1138 * no order checking is needed.
1139 */
1140 lock_list = td->td_sleeplocks;
1141 if (lock_list == NULL || lock_list->ll_count == 0)
1142 return;
1143 } else {
1144
1145 /*
1146 * If this is the first lock, just return as no order
1147 * checking is needed. Avoid problems with thread
1148 * migration pinning the thread while checking if
1149 * spinlocks are held. If at least one spinlock is held
1150 * the thread is in a safe path and it is allowed to
1151 * unpin it.
1152 */
1153 sched_pin();
1154 lock_list = PCPU_GET(spinlocks);
1155 if (lock_list == NULL || lock_list->ll_count == 0) {
1156 sched_unpin();
1157 return;
1158 }
1159 sched_unpin();
1160 }
1161
1162 /*
1163 * Check to see if we are recursing on a lock we already own. If
1164 * so, make sure that we don't mismatch exclusive and shared lock
1165 * acquires.
1166 */
1167 lock1 = find_instance(lock_list, lock);
1168 if (lock1 != NULL) {
1169 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 &&
1170 (flags & LOP_EXCLUSIVE) == 0) {
1171 witness_output("shared lock of (%s) %s @ %s:%d\n",
1172 class->lc_name, lock->lo_name,
1173 fixup_filename(file), line);
1174 witness_output("while exclusively locked from %s:%d\n",
1175 fixup_filename(lock1->li_file), lock1->li_line);
1176 kassert_panic("excl->share");
1177 }
1178 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 &&
1179 (flags & LOP_EXCLUSIVE) != 0) {
1180 witness_output("exclusive lock of (%s) %s @ %s:%d\n",
1181 class->lc_name, lock->lo_name,
1182 fixup_filename(file), line);
1183 witness_output("while share locked from %s:%d\n",
1184 fixup_filename(lock1->li_file), lock1->li_line);
1185 kassert_panic("share->excl");
1186 }
1187 return;
1188 }
1189
1190 /* Warn if the interlock is not locked exactly once. */
1191 if (interlock != NULL) {
1192 iclass = LOCK_CLASS(interlock);
1193 lock1 = find_instance(lock_list, interlock);
1194 if (lock1 == NULL)
1195 kassert_panic("interlock (%s) %s not locked @ %s:%d",
1196 iclass->lc_name, interlock->lo_name,
1197 fixup_filename(file), line);
1198 else if ((lock1->li_flags & LI_RECURSEMASK) != 0)
1199 kassert_panic("interlock (%s) %s recursed @ %s:%d",
1200 iclass->lc_name, interlock->lo_name,
1201 fixup_filename(file), line);
1202 }
1203
1204 /*
1205 * Find the previously acquired lock, but ignore interlocks.
1206 */
1207 plock = &lock_list->ll_children[lock_list->ll_count - 1];
1208 if (interlock != NULL && plock->li_lock == interlock) {
1209 if (lock_list->ll_count > 1)
1210 plock =
1211 &lock_list->ll_children[lock_list->ll_count - 2];
1212 else {
1213 lle = lock_list->ll_next;
1214
1215 /*
1216 * The interlock is the only lock we hold, so
1217 * simply return.
1218 */
1219 if (lle == NULL)
1220 return;
1221 plock = &lle->ll_children[lle->ll_count - 1];
1222 }
1223 }
1224
1225 /*
1226 * Try to perform most checks without a lock. If this succeeds we
1227 * can skip acquiring the lock and return success. Otherwise we redo
1228 * the check with the lock held to handle races with concurrent updates.
1229 */
1230 w1 = plock->li_lock->lo_witness;
1231 if (witness_lock_order_check(w1, w))
1232 return;
1233
1234 mtx_lock_spin(&w_mtx);
1235 if (witness_lock_order_check(w1, w)) {
1236 mtx_unlock_spin(&w_mtx);
1237 return;
1238 }
1239 witness_lock_order_add(w1, w);
1240
1241 /*
1242 * Check for duplicate locks of the same type. Note that we only
1243 * have to check for this on the last lock we just acquired. Any
1244 * other cases will be caught as lock order violations.
1245 */
1246 if (w1 == w) {
1247 i = w->w_index;
1248 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) &&
1249 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) {
1250 w_rmatrix[i][i] |= WITNESS_REVERSAL;
1251 w->w_reversed = 1;
1252 mtx_unlock_spin(&w_mtx);
1253 witness_output(
1254 "acquiring duplicate lock of same type: \"%s\"\n",
1255 w->w_name);
1256 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name,
1257 fixup_filename(plock->li_file), plock->li_line);
1258 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name,
1259 fixup_filename(file), line);
1260 witness_debugger(1, __func__);
1261 } else
1262 mtx_unlock_spin(&w_mtx);
1263 return;
1264 }
1265 mtx_assert(&w_mtx, MA_OWNED);
1266
1267 /*
1268 * If we know that the lock we are acquiring comes after
1269 * the lock we most recently acquired in the lock order tree,
1270 * then there is no need for any further checks.
1271 */
1272 if (isitmychild(w1, w))
1273 goto out;
1274
1275 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) {
1276 for (i = lle->ll_count - 1; i >= 0; i--, j++) {
1277
1278 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN);
1279 lock1 = &lle->ll_children[i];
1280
1281 /*
1282 * Ignore the interlock.
1283 */
1284 if (interlock == lock1->li_lock)
1285 continue;
1286
1287 /*
1288 * If this lock doesn't undergo witness checking,
1289 * then skip it.
1290 */
1291 w1 = lock1->li_lock->lo_witness;
1292 if (w1 == NULL) {
1293 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0,
1294 ("lock missing witness structure"));
1295 continue;
1296 }
1297
1298 /*
1299 * If we are locking Giant and this is a sleepable
1300 * lock, then skip it.
1301 */
1302 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 &&
1303 lock == &Giant.lock_object)
1304 continue;
1305
1306 /*
1307 * If we are locking a sleepable lock and this lock
1308 * is Giant, then skip it.
1309 */
1310 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1311 lock1->li_lock == &Giant.lock_object)
1312 continue;
1313
1314 /*
1315 * If we are locking a sleepable lock and this lock
1316 * isn't sleepable, we want to treat it as a lock
1317 * order violation to enfore a general lock order of
1318 * sleepable locks before non-sleepable locks.
1319 */
1320 if (((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1321 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0))
1322 goto reversal;
1323
1324 /*
1325 * If we are locking Giant and this is a non-sleepable
1326 * lock, then treat it as a reversal.
1327 */
1328 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 &&
1329 lock == &Giant.lock_object)
1330 goto reversal;
1331
1332 /*
1333 * Check the lock order hierarchy for a reveresal.
1334 */
1335 if (!isitmydescendant(w, w1))
1336 continue;
1337 reversal:
1338
1339 /*
1340 * We have a lock order violation, check to see if it
1341 * is allowed or has already been yelled about.
1342 */
1343 #ifdef BLESSING
1344
1345 /*
1346 * If the lock order is blessed, just bail. We don't
1347 * look for other lock order violations though, which
1348 * may be a bug.
1349 */
1350 if (blessed(w, w1))
1351 goto out;
1352 #endif
1353
1354 /* Bail if this violation is known */
1355 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL)
1356 goto out;
1357
1358 /* Record this as a violation */
1359 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL;
1360 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL;
1361 w->w_reversed = w1->w_reversed = 1;
1362 witness_increment_graph_generation();
1363 mtx_unlock_spin(&w_mtx);
1364
1365 #ifdef WITNESS_NO_VNODE
1366 /*
1367 * There are known LORs between VNODE locks. They are
1368 * not an indication of a bug. VNODE locks are flagged
1369 * as such (LO_IS_VNODE) and we don't yell if the LOR
1370 * is between 2 VNODE locks.
1371 */
1372 if ((lock->lo_flags & LO_IS_VNODE) != 0 &&
1373 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0)
1374 return;
1375 #endif
1376
1377 /*
1378 * Ok, yell about it.
1379 */
1380 if (((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1381 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0))
1382 witness_output(
1383 "lock order reversal: (sleepable after non-sleepable)\n");
1384 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0
1385 && lock == &Giant.lock_object)
1386 witness_output(
1387 "lock order reversal: (Giant after non-sleepable)\n");
1388 else
1389 witness_output("lock order reversal:\n");
1390
1391 /*
1392 * Try to locate an earlier lock with
1393 * witness w in our list.
1394 */
1395 do {
1396 lock2 = &lle->ll_children[i];
1397 MPASS(lock2->li_lock != NULL);
1398 if (lock2->li_lock->lo_witness == w)
1399 break;
1400 if (i == 0 && lle->ll_next != NULL) {
1401 lle = lle->ll_next;
1402 i = lle->ll_count - 1;
1403 MPASS(i >= 0 && i < LOCK_NCHILDREN);
1404 } else
1405 i--;
1406 } while (i >= 0);
1407 if (i < 0) {
1408 witness_output(" 1st %p %s (%s) @ %s:%d\n",
1409 lock1->li_lock, lock1->li_lock->lo_name,
1410 w1->w_name, fixup_filename(lock1->li_file),
1411 lock1->li_line);
1412 witness_output(" 2nd %p %s (%s) @ %s:%d\n", lock,
1413 lock->lo_name, w->w_name,
1414 fixup_filename(file), line);
1415 } else {
1416 witness_output(" 1st %p %s (%s) @ %s:%d\n",
1417 lock2->li_lock, lock2->li_lock->lo_name,
1418 lock2->li_lock->lo_witness->w_name,
1419 fixup_filename(lock2->li_file),
1420 lock2->li_line);
1421 witness_output(" 2nd %p %s (%s) @ %s:%d\n",
1422 lock1->li_lock, lock1->li_lock->lo_name,
1423 w1->w_name, fixup_filename(lock1->li_file),
1424 lock1->li_line);
1425 witness_output(" 3rd %p %s (%s) @ %s:%d\n", lock,
1426 lock->lo_name, w->w_name,
1427 fixup_filename(file), line);
1428 }
1429 witness_debugger(1, __func__);
1430 return;
1431 }
1432 }
1433
1434 /*
1435 * If requested, build a new lock order. However, don't build a new
1436 * relationship between a sleepable lock and Giant if it is in the
1437 * wrong direction. The correct lock order is that sleepable locks
1438 * always come before Giant.
1439 */
1440 if (flags & LOP_NEWORDER &&
1441 !(plock->li_lock == &Giant.lock_object &&
1442 (lock->lo_flags & LO_SLEEPABLE) != 0)) {
1443 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
1444 w->w_name, plock->li_lock->lo_witness->w_name);
1445 itismychild(plock->li_lock->lo_witness, w);
1446 }
1447 out:
1448 mtx_unlock_spin(&w_mtx);
1449 }
1450
1451 void
1452 witness_lock(struct lock_object *lock, int flags, const char *file, int line)
1453 {
1454 struct lock_list_entry **lock_list, *lle;
1455 struct lock_instance *instance;
1456 struct witness *w;
1457 struct thread *td;
1458
1459 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL ||
1460 panicstr != NULL)
1461 return;
1462 w = lock->lo_witness;
1463 td = curthread;
1464
1465 /* Determine lock list for this lock. */
1466 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK)
1467 lock_list = &td->td_sleeplocks;
1468 else
1469 lock_list = PCPU_PTR(spinlocks);
1470
1471 /* Check to see if we are recursing on a lock we already own. */
1472 instance = find_instance(*lock_list, lock);
1473 if (instance != NULL) {
1474 instance->li_flags++;
1475 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__,
1476 td->td_proc->p_pid, lock->lo_name,
1477 instance->li_flags & LI_RECURSEMASK);
1478 instance->li_file = file;
1479 instance->li_line = line;
1480 return;
1481 }
1482
1483 /* Update per-witness last file and line acquire. */
1484 w->w_file = file;
1485 w->w_line = line;
1486
1487 /* Find the next open lock instance in the list and fill it. */
1488 lle = *lock_list;
1489 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) {
1490 lle = witness_lock_list_get();
1491 if (lle == NULL)
1492 return;
1493 lle->ll_next = *lock_list;
1494 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__,
1495 td->td_proc->p_pid, lle);
1496 *lock_list = lle;
1497 }
1498 instance = &lle->ll_children[lle->ll_count++];
1499 instance->li_lock = lock;
1500 instance->li_line = line;
1501 instance->li_file = file;
1502 if ((flags & LOP_EXCLUSIVE) != 0)
1503 instance->li_flags = LI_EXCLUSIVE;
1504 else
1505 instance->li_flags = 0;
1506 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__,
1507 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1);
1508 }
1509
1510 void
1511 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line)
1512 {
1513 struct lock_instance *instance;
1514 struct lock_class *class;
1515
1516 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1517 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
1518 return;
1519 class = LOCK_CLASS(lock);
1520 if (witness_watch) {
1521 if ((lock->lo_flags & LO_UPGRADABLE) == 0)
1522 kassert_panic(
1523 "upgrade of non-upgradable lock (%s) %s @ %s:%d",
1524 class->lc_name, lock->lo_name,
1525 fixup_filename(file), line);
1526 if ((class->lc_flags & LC_SLEEPLOCK) == 0)
1527 kassert_panic(
1528 "upgrade of non-sleep lock (%s) %s @ %s:%d",
1529 class->lc_name, lock->lo_name,
1530 fixup_filename(file), line);
1531 }
1532 instance = find_instance(curthread->td_sleeplocks, lock);
1533 if (instance == NULL) {
1534 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d",
1535 class->lc_name, lock->lo_name,
1536 fixup_filename(file), line);
1537 return;
1538 }
1539 if (witness_watch) {
1540 if ((instance->li_flags & LI_EXCLUSIVE) != 0)
1541 kassert_panic(
1542 "upgrade of exclusive lock (%s) %s @ %s:%d",
1543 class->lc_name, lock->lo_name,
1544 fixup_filename(file), line);
1545 if ((instance->li_flags & LI_RECURSEMASK) != 0)
1546 kassert_panic(
1547 "upgrade of recursed lock (%s) %s r=%d @ %s:%d",
1548 class->lc_name, lock->lo_name,
1549 instance->li_flags & LI_RECURSEMASK,
1550 fixup_filename(file), line);
1551 }
1552 instance->li_flags |= LI_EXCLUSIVE;
1553 }
1554
1555 void
1556 witness_downgrade(struct lock_object *lock, int flags, const char *file,
1557 int line)
1558 {
1559 struct lock_instance *instance;
1560 struct lock_class *class;
1561
1562 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1563 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
1564 return;
1565 class = LOCK_CLASS(lock);
1566 if (witness_watch) {
1567 if ((lock->lo_flags & LO_UPGRADABLE) == 0)
1568 kassert_panic(
1569 "downgrade of non-upgradable lock (%s) %s @ %s:%d",
1570 class->lc_name, lock->lo_name,
1571 fixup_filename(file), line);
1572 if ((class->lc_flags & LC_SLEEPLOCK) == 0)
1573 kassert_panic(
1574 "downgrade of non-sleep lock (%s) %s @ %s:%d",
1575 class->lc_name, lock->lo_name,
1576 fixup_filename(file), line);
1577 }
1578 instance = find_instance(curthread->td_sleeplocks, lock);
1579 if (instance == NULL) {
1580 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d",
1581 class->lc_name, lock->lo_name,
1582 fixup_filename(file), line);
1583 return;
1584 }
1585 if (witness_watch) {
1586 if ((instance->li_flags & LI_EXCLUSIVE) == 0)
1587 kassert_panic(
1588 "downgrade of shared lock (%s) %s @ %s:%d",
1589 class->lc_name, lock->lo_name,
1590 fixup_filename(file), line);
1591 if ((instance->li_flags & LI_RECURSEMASK) != 0)
1592 kassert_panic(
1593 "downgrade of recursed lock (%s) %s r=%d @ %s:%d",
1594 class->lc_name, lock->lo_name,
1595 instance->li_flags & LI_RECURSEMASK,
1596 fixup_filename(file), line);
1597 }
1598 instance->li_flags &= ~LI_EXCLUSIVE;
1599 }
1600
1601 void
1602 witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
1603 {
1604 struct lock_list_entry **lock_list, *lle;
1605 struct lock_instance *instance;
1606 struct lock_class *class;
1607 struct thread *td;
1608 register_t s;
1609 int i, j;
1610
1611 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL)
1612 return;
1613 td = curthread;
1614 class = LOCK_CLASS(lock);
1615
1616 /* Find lock instance associated with this lock. */
1617 if (class->lc_flags & LC_SLEEPLOCK)
1618 lock_list = &td->td_sleeplocks;
1619 else
1620 lock_list = PCPU_PTR(spinlocks);
1621 lle = *lock_list;
1622 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next)
1623 for (i = 0; i < (*lock_list)->ll_count; i++) {
1624 instance = &(*lock_list)->ll_children[i];
1625 if (instance->li_lock == lock)
1626 goto found;
1627 }
1628
1629 /*
1630 * When disabling WITNESS through witness_watch we could end up in
1631 * having registered locks in the td_sleeplocks queue.
1632 * We have to make sure we flush these queues, so just search for
1633 * eventual register locks and remove them.
1634 */
1635 if (witness_watch > 0) {
1636 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name,
1637 lock->lo_name, fixup_filename(file), line);
1638 return;
1639 } else {
1640 return;
1641 }
1642 found:
1643
1644 /* First, check for shared/exclusive mismatches. */
1645 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 &&
1646 (flags & LOP_EXCLUSIVE) == 0) {
1647 witness_output("shared unlock of (%s) %s @ %s:%d\n",
1648 class->lc_name, lock->lo_name, fixup_filename(file), line);
1649 witness_output("while exclusively locked from %s:%d\n",
1650 fixup_filename(instance->li_file), instance->li_line);
1651 kassert_panic("excl->ushare");
1652 }
1653 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 &&
1654 (flags & LOP_EXCLUSIVE) != 0) {
1655 witness_output("exclusive unlock of (%s) %s @ %s:%d\n",
1656 class->lc_name, lock->lo_name, fixup_filename(file), line);
1657 witness_output("while share locked from %s:%d\n",
1658 fixup_filename(instance->li_file),
1659 instance->li_line);
1660 kassert_panic("share->uexcl");
1661 }
1662 /* If we are recursed, unrecurse. */
1663 if ((instance->li_flags & LI_RECURSEMASK) > 0) {
1664 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__,
1665 td->td_proc->p_pid, instance->li_lock->lo_name,
1666 instance->li_flags);
1667 instance->li_flags--;
1668 return;
1669 }
1670 /* The lock is now being dropped, check for NORELEASE flag */
1671 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) {
1672 witness_output("forbidden unlock of (%s) %s @ %s:%d\n",
1673 class->lc_name, lock->lo_name, fixup_filename(file), line);
1674 kassert_panic("lock marked norelease");
1675 }
1676
1677 /* Otherwise, remove this item from the list. */
1678 s = intr_disable();
1679 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__,
1680 td->td_proc->p_pid, instance->li_lock->lo_name,
1681 (*lock_list)->ll_count - 1);
1682 for (j = i; j < (*lock_list)->ll_count - 1; j++)
1683 (*lock_list)->ll_children[j] =
1684 (*lock_list)->ll_children[j + 1];
1685 (*lock_list)->ll_count--;
1686 intr_restore(s);
1687
1688 /*
1689 * In order to reduce contention on w_mtx, we want to keep always an
1690 * head object into lists so that frequent allocation from the
1691 * free witness pool (and subsequent locking) is avoided.
1692 * In order to maintain the current code simple, when the head
1693 * object is totally unloaded it means also that we do not have
1694 * further objects in the list, so the list ownership needs to be
1695 * hand over to another object if the current head needs to be freed.
1696 */
1697 if ((*lock_list)->ll_count == 0) {
1698 if (*lock_list == lle) {
1699 if (lle->ll_next == NULL)
1700 return;
1701 } else
1702 lle = *lock_list;
1703 *lock_list = lle->ll_next;
1704 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__,
1705 td->td_proc->p_pid, lle);
1706 witness_lock_list_free(lle);
1707 }
1708 }
1709
1710 void
1711 witness_thread_exit(struct thread *td)
1712 {
1713 struct lock_list_entry *lle;
1714 int i, n;
1715
1716 lle = td->td_sleeplocks;
1717 if (lle == NULL || panicstr != NULL)
1718 return;
1719 if (lle->ll_count != 0) {
1720 for (n = 0; lle != NULL; lle = lle->ll_next)
1721 for (i = lle->ll_count - 1; i >= 0; i--) {
1722 if (n == 0)
1723 witness_output(
1724 "Thread %p exiting with the following locks held:\n", td);
1725 n++;
1726 witness_list_lock(&lle->ll_children[i],
1727 witness_output);
1728
1729 }
1730 kassert_panic(
1731 "Thread %p cannot exit while holding sleeplocks\n", td);
1732 }
1733 witness_lock_list_free(lle);
1734 }
1735
1736 /*
1737 * Warn if any locks other than 'lock' are held. Flags can be passed in to
1738 * exempt Giant and sleepable locks from the checks as well. If any
1739 * non-exempt locks are held, then a supplied message is printed to the
1740 * output channel along with a list of the offending locks. If indicated in the
1741 * flags then a failure results in a panic as well.
1742 */
1743 int
1744 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...)
1745 {
1746 struct lock_list_entry *lock_list, *lle;
1747 struct lock_instance *lock1;
1748 struct thread *td;
1749 va_list ap;
1750 int i, n;
1751
1752 if (witness_cold || witness_watch < 1 || panicstr != NULL)
1753 return (0);
1754 n = 0;
1755 td = curthread;
1756 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next)
1757 for (i = lle->ll_count - 1; i >= 0; i--) {
1758 lock1 = &lle->ll_children[i];
1759 if (lock1->li_lock == lock)
1760 continue;
1761 if (flags & WARN_GIANTOK &&
1762 lock1->li_lock == &Giant.lock_object)
1763 continue;
1764 if (flags & WARN_SLEEPOK &&
1765 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0)
1766 continue;
1767 if (n == 0) {
1768 va_start(ap, fmt);
1769 vprintf(fmt, ap);
1770 va_end(ap);
1771 printf(" with the following %slocks held:\n",
1772 (flags & WARN_SLEEPOK) != 0 ?
1773 "non-sleepable " : "");
1774 }
1775 n++;
1776 witness_list_lock(lock1, printf);
1777 }
1778
1779 /*
1780 * Pin the thread in order to avoid problems with thread migration.
1781 * Once that all verifies are passed about spinlocks ownership,
1782 * the thread is in a safe path and it can be unpinned.
1783 */
1784 sched_pin();
1785 lock_list = PCPU_GET(spinlocks);
1786 if (lock_list != NULL && lock_list->ll_count != 0) {
1787 sched_unpin();
1788
1789 /*
1790 * We should only have one spinlock and as long as
1791 * the flags cannot match for this locks class,
1792 * check if the first spinlock is the one curthread
1793 * should hold.
1794 */
1795 lock1 = &lock_list->ll_children[lock_list->ll_count - 1];
1796 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL &&
1797 lock1->li_lock == lock && n == 0)
1798 return (0);
1799
1800 va_start(ap, fmt);
1801 vprintf(fmt, ap);
1802 va_end(ap);
1803 printf(" with the following %slocks held:\n",
1804 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : "");
1805 n += witness_list_locks(&lock_list, printf);
1806 } else
1807 sched_unpin();
1808 if (flags & WARN_PANIC && n)
1809 kassert_panic("%s", __func__);
1810 else
1811 witness_debugger(n, __func__);
1812 return (n);
1813 }
1814
1815 const char *
1816 witness_file(struct lock_object *lock)
1817 {
1818 struct witness *w;
1819
1820 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
1821 return ("?");
1822 w = lock->lo_witness;
1823 return (w->w_file);
1824 }
1825
1826 int
1827 witness_line(struct lock_object *lock)
1828 {
1829 struct witness *w;
1830
1831 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
1832 return (0);
1833 w = lock->lo_witness;
1834 return (w->w_line);
1835 }
1836
1837 static struct witness *
1838 enroll(const char *description, struct lock_class *lock_class)
1839 {
1840 struct witness *w;
1841
1842 MPASS(description != NULL);
1843
1844 if (witness_watch == -1 || panicstr != NULL)
1845 return (NULL);
1846 if ((lock_class->lc_flags & LC_SPINLOCK)) {
1847 if (witness_skipspin)
1848 return (NULL);
1849 } else if ((lock_class->lc_flags & LC_SLEEPLOCK) == 0) {
1850 kassert_panic("lock class %s is not sleep or spin",
1851 lock_class->lc_name);
1852 return (NULL);
1853 }
1854
1855 mtx_lock_spin(&w_mtx);
1856 w = witness_hash_get(description);
1857 if (w)
1858 goto found;
1859 if ((w = witness_get()) == NULL)
1860 return (NULL);
1861 MPASS(strlen(description) < MAX_W_NAME);
1862 strcpy(w->w_name, description);
1863 w->w_class = lock_class;
1864 w->w_refcount = 1;
1865 STAILQ_INSERT_HEAD(&w_all, w, w_list);
1866 if (lock_class->lc_flags & LC_SPINLOCK) {
1867 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist);
1868 w_spin_cnt++;
1869 } else if (lock_class->lc_flags & LC_SLEEPLOCK) {
1870 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist);
1871 w_sleep_cnt++;
1872 }
1873
1874 /* Insert new witness into the hash */
1875 witness_hash_put(w);
1876 witness_increment_graph_generation();
1877 mtx_unlock_spin(&w_mtx);
1878 return (w);
1879 found:
1880 w->w_refcount++;
1881 if (w->w_refcount == 1)
1882 w->w_class = lock_class;
1883 mtx_unlock_spin(&w_mtx);
1884 if (lock_class != w->w_class)
1885 kassert_panic(
1886 "lock (%s) %s does not match earlier (%s) lock",
1887 description, lock_class->lc_name,
1888 w->w_class->lc_name);
1889 return (w);
1890 }
1891
1892 static void
1893 depart(struct witness *w)
1894 {
1895
1896 MPASS(w->w_refcount == 0);
1897 if (w->w_class->lc_flags & LC_SLEEPLOCK) {
1898 w_sleep_cnt--;
1899 } else {
1900 w_spin_cnt--;
1901 }
1902 /*
1903 * Set file to NULL as it may point into a loadable module.
1904 */
1905 w->w_file = NULL;
1906 w->w_line = 0;
1907 witness_increment_graph_generation();
1908 }
1909
1910
1911 static void
1912 adopt(struct witness *parent, struct witness *child)
1913 {
1914 int pi, ci, i, j;
1915
1916 if (witness_cold == 0)
1917 mtx_assert(&w_mtx, MA_OWNED);
1918
1919 /* If the relationship is already known, there's no work to be done. */
1920 if (isitmychild(parent, child))
1921 return;
1922
1923 /* When the structure of the graph changes, bump up the generation. */
1924 witness_increment_graph_generation();
1925
1926 /*
1927 * The hard part ... create the direct relationship, then propagate all
1928 * indirect relationships.
1929 */
1930 pi = parent->w_index;
1931 ci = child->w_index;
1932 WITNESS_INDEX_ASSERT(pi);
1933 WITNESS_INDEX_ASSERT(ci);
1934 MPASS(pi != ci);
1935 w_rmatrix[pi][ci] |= WITNESS_PARENT;
1936 w_rmatrix[ci][pi] |= WITNESS_CHILD;
1937
1938 /*
1939 * If parent was not already an ancestor of child,
1940 * then we increment the descendant and ancestor counters.
1941 */
1942 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) {
1943 parent->w_num_descendants++;
1944 child->w_num_ancestors++;
1945 }
1946
1947 /*
1948 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as
1949 * an ancestor of 'pi' during this loop.
1950 */
1951 for (i = 1; i <= w_max_used_index; i++) {
1952 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 &&
1953 (i != pi))
1954 continue;
1955
1956 /* Find each descendant of 'i' and mark it as a descendant. */
1957 for (j = 1; j <= w_max_used_index; j++) {
1958
1959 /*
1960 * Skip children that are already marked as
1961 * descendants of 'i'.
1962 */
1963 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK)
1964 continue;
1965
1966 /*
1967 * We are only interested in descendants of 'ci'. Note
1968 * that 'ci' itself is counted as a descendant of 'ci'.
1969 */
1970 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 &&
1971 (j != ci))
1972 continue;
1973 w_rmatrix[i][j] |= WITNESS_ANCESTOR;
1974 w_rmatrix[j][i] |= WITNESS_DESCENDANT;
1975 w_data[i].w_num_descendants++;
1976 w_data[j].w_num_ancestors++;
1977
1978 /*
1979 * Make sure we aren't marking a node as both an
1980 * ancestor and descendant. We should have caught
1981 * this as a lock order reversal earlier.
1982 */
1983 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) &&
1984 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) {
1985 printf("witness rmatrix paradox! [%d][%d]=%d "
1986 "both ancestor and descendant\n",
1987 i, j, w_rmatrix[i][j]);
1988 kdb_backtrace();
1989 printf("Witness disabled.\n");
1990 witness_watch = -1;
1991 }
1992 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) &&
1993 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) {
1994 printf("witness rmatrix paradox! [%d][%d]=%d "
1995 "both ancestor and descendant\n",
1996 j, i, w_rmatrix[j][i]);
1997 kdb_backtrace();
1998 printf("Witness disabled.\n");
1999 witness_watch = -1;
2000 }
2001 }
2002 }
2003 }
2004
2005 static void
2006 itismychild(struct witness *parent, struct witness *child)
2007 {
2008 int unlocked;
2009
2010 MPASS(child != NULL && parent != NULL);
2011 if (witness_cold == 0)
2012 mtx_assert(&w_mtx, MA_OWNED);
2013
2014 if (!witness_lock_type_equal(parent, child)) {
2015 if (witness_cold == 0) {
2016 unlocked = 1;
2017 mtx_unlock_spin(&w_mtx);
2018 } else {
2019 unlocked = 0;
2020 }
2021 kassert_panic(
2022 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not "
2023 "the same lock type", __func__, parent->w_name,
2024 parent->w_class->lc_name, child->w_name,
2025 child->w_class->lc_name);
2026 if (unlocked)
2027 mtx_lock_spin(&w_mtx);
2028 }
2029 adopt(parent, child);
2030 }
2031
2032 /*
2033 * Generic code for the isitmy*() functions. The rmask parameter is the
2034 * expected relationship of w1 to w2.
2035 */
2036 static int
2037 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname)
2038 {
2039 unsigned char r1, r2;
2040 int i1, i2;
2041
2042 i1 = w1->w_index;
2043 i2 = w2->w_index;
2044 WITNESS_INDEX_ASSERT(i1);
2045 WITNESS_INDEX_ASSERT(i2);
2046 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK;
2047 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK;
2048
2049 /* The flags on one better be the inverse of the flags on the other */
2050 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) ||
2051 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) {
2052 /* Don't squawk if we're potentially racing with an update. */
2053 if (!mtx_owned(&w_mtx))
2054 return (0);
2055 printf("%s: rmatrix mismatch between %s (index %d) and %s "
2056 "(index %d): w_rmatrix[%d][%d] == %hhx but "
2057 "w_rmatrix[%d][%d] == %hhx\n",
2058 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1,
2059 i2, i1, r2);
2060 kdb_backtrace();
2061 printf("Witness disabled.\n");
2062 witness_watch = -1;
2063 }
2064 return (r1 & rmask);
2065 }
2066
2067 /*
2068 * Checks if @child is a direct child of @parent.
2069 */
2070 static int
2071 isitmychild(struct witness *parent, struct witness *child)
2072 {
2073
2074 return (_isitmyx(parent, child, WITNESS_PARENT, __func__));
2075 }
2076
2077 /*
2078 * Checks if @descendant is a direct or inderect descendant of @ancestor.
2079 */
2080 static int
2081 isitmydescendant(struct witness *ancestor, struct witness *descendant)
2082 {
2083
2084 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK,
2085 __func__));
2086 }
2087
2088 #ifdef BLESSING
2089 static int
2090 blessed(struct witness *w1, struct witness *w2)
2091 {
2092 int i;
2093 struct witness_blessed *b;
2094
2095 for (i = 0; i < nitems(blessed_list); i++) {
2096 b = &blessed_list[i];
2097 if (strcmp(w1->w_name, b->b_lock1) == 0) {
2098 if (strcmp(w2->w_name, b->b_lock2) == 0)
2099 return (1);
2100 continue;
2101 }
2102 if (strcmp(w1->w_name, b->b_lock2) == 0)
2103 if (strcmp(w2->w_name, b->b_lock1) == 0)
2104 return (1);
2105 }
2106 return (0);
2107 }
2108 #endif
2109
2110 static struct witness *
2111 witness_get(void)
2112 {
2113 struct witness *w;
2114 int index;
2115
2116 if (witness_cold == 0)
2117 mtx_assert(&w_mtx, MA_OWNED);
2118
2119 if (witness_watch == -1) {
2120 mtx_unlock_spin(&w_mtx);
2121 return (NULL);
2122 }
2123 if (STAILQ_EMPTY(&w_free)) {
2124 witness_watch = -1;
2125 mtx_unlock_spin(&w_mtx);
2126 printf("WITNESS: unable to allocate a new witness object\n");
2127 return (NULL);
2128 }
2129 w = STAILQ_FIRST(&w_free);
2130 STAILQ_REMOVE_HEAD(&w_free, w_list);
2131 w_free_cnt--;
2132 index = w->w_index;
2133 MPASS(index > 0 && index == w_max_used_index+1 &&
2134 index < witness_count);
2135 bzero(w, sizeof(*w));
2136 w->w_index = index;
2137 if (index > w_max_used_index)
2138 w_max_used_index = index;
2139 return (w);
2140 }
2141
2142 static void
2143 witness_free(struct witness *w)
2144 {
2145
2146 STAILQ_INSERT_HEAD(&w_free, w, w_list);
2147 w_free_cnt++;
2148 }
2149
2150 static struct lock_list_entry *
2151 witness_lock_list_get(void)
2152 {
2153 struct lock_list_entry *lle;
2154
2155 if (witness_watch == -1)
2156 return (NULL);
2157 mtx_lock_spin(&w_mtx);
2158 lle = w_lock_list_free;
2159 if (lle == NULL) {
2160 witness_watch = -1;
2161 mtx_unlock_spin(&w_mtx);
2162 printf("%s: witness exhausted\n", __func__);
2163 return (NULL);
2164 }
2165 w_lock_list_free = lle->ll_next;
2166 mtx_unlock_spin(&w_mtx);
2167 bzero(lle, sizeof(*lle));
2168 return (lle);
2169 }
2170
2171 static void
2172 witness_lock_list_free(struct lock_list_entry *lle)
2173 {
2174
2175 mtx_lock_spin(&w_mtx);
2176 lle->ll_next = w_lock_list_free;
2177 w_lock_list_free = lle;
2178 mtx_unlock_spin(&w_mtx);
2179 }
2180
2181 static struct lock_instance *
2182 find_instance(struct lock_list_entry *list, const struct lock_object *lock)
2183 {
2184 struct lock_list_entry *lle;
2185 struct lock_instance *instance;
2186 int i;
2187
2188 for (lle = list; lle != NULL; lle = lle->ll_next)
2189 for (i = lle->ll_count - 1; i >= 0; i--) {
2190 instance = &lle->ll_children[i];
2191 if (instance->li_lock == lock)
2192 return (instance);
2193 }
2194 return (NULL);
2195 }
2196
2197 static void
2198 witness_list_lock(struct lock_instance *instance,
2199 int (*prnt)(const char *fmt, ...))
2200 {
2201 struct lock_object *lock;
2202
2203 lock = instance->li_lock;
2204 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ?
2205 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name);
2206 if (lock->lo_witness->w_name != lock->lo_name)
2207 prnt(" (%s)", lock->lo_witness->w_name);
2208 prnt(" r = %d (%p) locked @ %s:%d\n",
2209 instance->li_flags & LI_RECURSEMASK, lock,
2210 fixup_filename(instance->li_file), instance->li_line);
2211 }
2212
2213 static int
2214 witness_output(const char *fmt, ...)
2215 {
2216 va_list ap;
2217 int ret;
2218
2219 va_start(ap, fmt);
2220 ret = witness_voutput(fmt, ap);
2221 va_end(ap);
2222 return (ret);
2223 }
2224
2225 static int
2226 witness_voutput(const char *fmt, va_list ap)
2227 {
2228 int ret;
2229
2230 ret = 0;
2231 switch (witness_channel) {
2232 case WITNESS_CONSOLE:
2233 ret = vprintf(fmt, ap);
2234 break;
2235 case WITNESS_LOG:
2236 vlog(LOG_NOTICE, fmt, ap);
2237 break;
2238 case WITNESS_NONE:
2239 break;
2240 }
2241 return (ret);
2242 }
2243
2244 #ifdef DDB
2245 static int
2246 witness_thread_has_locks(struct thread *td)
2247 {
2248
2249 if (td->td_sleeplocks == NULL)
2250 return (0);
2251 return (td->td_sleeplocks->ll_count != 0);
2252 }
2253
2254 static int
2255 witness_proc_has_locks(struct proc *p)
2256 {
2257 struct thread *td;
2258
2259 FOREACH_THREAD_IN_PROC(p, td) {
2260 if (witness_thread_has_locks(td))
2261 return (1);
2262 }
2263 return (0);
2264 }
2265 #endif
2266
2267 int
2268 witness_list_locks(struct lock_list_entry **lock_list,
2269 int (*prnt)(const char *fmt, ...))
2270 {
2271 struct lock_list_entry *lle;
2272 int i, nheld;
2273
2274 nheld = 0;
2275 for (lle = *lock_list; lle != NULL; lle = lle->ll_next)
2276 for (i = lle->ll_count - 1; i >= 0; i--) {
2277 witness_list_lock(&lle->ll_children[i], prnt);
2278 nheld++;
2279 }
2280 return (nheld);
2281 }
2282
2283 /*
2284 * This is a bit risky at best. We call this function when we have timed
2285 * out acquiring a spin lock, and we assume that the other CPU is stuck
2286 * with this lock held. So, we go groveling around in the other CPU's
2287 * per-cpu data to try to find the lock instance for this spin lock to
2288 * see when it was last acquired.
2289 */
2290 void
2291 witness_display_spinlock(struct lock_object *lock, struct thread *owner,
2292 int (*prnt)(const char *fmt, ...))
2293 {
2294 struct lock_instance *instance;
2295 struct pcpu *pc;
2296
2297 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU)
2298 return;
2299 pc = pcpu_find(owner->td_oncpu);
2300 instance = find_instance(pc->pc_spinlocks, lock);
2301 if (instance != NULL)
2302 witness_list_lock(instance, prnt);
2303 }
2304
2305 void
2306 witness_save(struct lock_object *lock, const char **filep, int *linep)
2307 {
2308 struct lock_list_entry *lock_list;
2309 struct lock_instance *instance;
2310 struct lock_class *class;
2311
2312 /*
2313 * This function is used independently in locking code to deal with
2314 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant
2315 * is gone.
2316 */
2317 if (SCHEDULER_STOPPED())
2318 return;
2319 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2320 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2321 return;
2322 class = LOCK_CLASS(lock);
2323 if (class->lc_flags & LC_SLEEPLOCK)
2324 lock_list = curthread->td_sleeplocks;
2325 else {
2326 if (witness_skipspin)
2327 return;
2328 lock_list = PCPU_GET(spinlocks);
2329 }
2330 instance = find_instance(lock_list, lock);
2331 if (instance == NULL) {
2332 kassert_panic("%s: lock (%s) %s not locked", __func__,
2333 class->lc_name, lock->lo_name);
2334 return;
2335 }
2336 *filep = instance->li_file;
2337 *linep = instance->li_line;
2338 }
2339
2340 void
2341 witness_restore(struct lock_object *lock, const char *file, int line)
2342 {
2343 struct lock_list_entry *lock_list;
2344 struct lock_instance *instance;
2345 struct lock_class *class;
2346
2347 /*
2348 * This function is used independently in locking code to deal with
2349 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant
2350 * is gone.
2351 */
2352 if (SCHEDULER_STOPPED())
2353 return;
2354 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2355 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2356 return;
2357 class = LOCK_CLASS(lock);
2358 if (class->lc_flags & LC_SLEEPLOCK)
2359 lock_list = curthread->td_sleeplocks;
2360 else {
2361 if (witness_skipspin)
2362 return;
2363 lock_list = PCPU_GET(spinlocks);
2364 }
2365 instance = find_instance(lock_list, lock);
2366 if (instance == NULL)
2367 kassert_panic("%s: lock (%s) %s not locked", __func__,
2368 class->lc_name, lock->lo_name);
2369 lock->lo_witness->w_file = file;
2370 lock->lo_witness->w_line = line;
2371 if (instance == NULL)
2372 return;
2373 instance->li_file = file;
2374 instance->li_line = line;
2375 }
2376
2377 void
2378 witness_assert(const struct lock_object *lock, int flags, const char *file,
2379 int line)
2380 {
2381 #ifdef INVARIANT_SUPPORT
2382 struct lock_instance *instance;
2383 struct lock_class *class;
2384
2385 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL)
2386 return;
2387 class = LOCK_CLASS(lock);
2388 if ((class->lc_flags & LC_SLEEPLOCK) != 0)
2389 instance = find_instance(curthread->td_sleeplocks, lock);
2390 else if ((class->lc_flags & LC_SPINLOCK) != 0)
2391 instance = find_instance(PCPU_GET(spinlocks), lock);
2392 else {
2393 kassert_panic("Lock (%s) %s is not sleep or spin!",
2394 class->lc_name, lock->lo_name);
2395 return;
2396 }
2397 switch (flags) {
2398 case LA_UNLOCKED:
2399 if (instance != NULL)
2400 kassert_panic("Lock (%s) %s locked @ %s:%d.",
2401 class->lc_name, lock->lo_name,
2402 fixup_filename(file), line);
2403 break;
2404 case LA_LOCKED:
2405 case LA_LOCKED | LA_RECURSED:
2406 case LA_LOCKED | LA_NOTRECURSED:
2407 case LA_SLOCKED:
2408 case LA_SLOCKED | LA_RECURSED:
2409 case LA_SLOCKED | LA_NOTRECURSED:
2410 case LA_XLOCKED:
2411 case LA_XLOCKED | LA_RECURSED:
2412 case LA_XLOCKED | LA_NOTRECURSED:
2413 if (instance == NULL) {
2414 kassert_panic("Lock (%s) %s not locked @ %s:%d.",
2415 class->lc_name, lock->lo_name,
2416 fixup_filename(file), line);
2417 break;
2418 }
2419 if ((flags & LA_XLOCKED) != 0 &&
2420 (instance->li_flags & LI_EXCLUSIVE) == 0)
2421 kassert_panic(
2422 "Lock (%s) %s not exclusively locked @ %s:%d.",
2423 class->lc_name, lock->lo_name,
2424 fixup_filename(file), line);
2425 if ((flags & LA_SLOCKED) != 0 &&
2426 (instance->li_flags & LI_EXCLUSIVE) != 0)
2427 kassert_panic(
2428 "Lock (%s) %s exclusively locked @ %s:%d.",
2429 class->lc_name, lock->lo_name,
2430 fixup_filename(file), line);
2431 if ((flags & LA_RECURSED) != 0 &&
2432 (instance->li_flags & LI_RECURSEMASK) == 0)
2433 kassert_panic("Lock (%s) %s not recursed @ %s:%d.",
2434 class->lc_name, lock->lo_name,
2435 fixup_filename(file), line);
2436 if ((flags & LA_NOTRECURSED) != 0 &&
2437 (instance->li_flags & LI_RECURSEMASK) != 0)
2438 kassert_panic("Lock (%s) %s recursed @ %s:%d.",
2439 class->lc_name, lock->lo_name,
2440 fixup_filename(file), line);
2441 break;
2442 default:
2443 kassert_panic("Invalid lock assertion at %s:%d.",
2444 fixup_filename(file), line);
2445
2446 }
2447 #endif /* INVARIANT_SUPPORT */
2448 }
2449
2450 static void
2451 witness_setflag(struct lock_object *lock, int flag, int set)
2452 {
2453 struct lock_list_entry *lock_list;
2454 struct lock_instance *instance;
2455 struct lock_class *class;
2456
2457 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2458 return;
2459 class = LOCK_CLASS(lock);
2460 if (class->lc_flags & LC_SLEEPLOCK)
2461 lock_list = curthread->td_sleeplocks;
2462 else {
2463 if (witness_skipspin)
2464 return;
2465 lock_list = PCPU_GET(spinlocks);
2466 }
2467 instance = find_instance(lock_list, lock);
2468 if (instance == NULL) {
2469 kassert_panic("%s: lock (%s) %s not locked", __func__,
2470 class->lc_name, lock->lo_name);
2471 return;
2472 }
2473
2474 if (set)
2475 instance->li_flags |= flag;
2476 else
2477 instance->li_flags &= ~flag;
2478 }
2479
2480 void
2481 witness_norelease(struct lock_object *lock)
2482 {
2483
2484 witness_setflag(lock, LI_NORELEASE, 1);
2485 }
2486
2487 void
2488 witness_releaseok(struct lock_object *lock)
2489 {
2490
2491 witness_setflag(lock, LI_NORELEASE, 0);
2492 }
2493
2494 #ifdef DDB
2495 static void
2496 witness_ddb_list(struct thread *td)
2497 {
2498
2499 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2500 KASSERT(kdb_active, ("%s: not in the debugger", __func__));
2501
2502 if (witness_watch < 1)
2503 return;
2504
2505 witness_list_locks(&td->td_sleeplocks, db_printf);
2506
2507 /*
2508 * We only handle spinlocks if td == curthread. This is somewhat broken
2509 * if td is currently executing on some other CPU and holds spin locks
2510 * as we won't display those locks. If we had a MI way of getting
2511 * the per-cpu data for a given cpu then we could use
2512 * td->td_oncpu to get the list of spinlocks for this thread
2513 * and "fix" this.
2514 *
2515 * That still wouldn't really fix this unless we locked the scheduler
2516 * lock or stopped the other CPU to make sure it wasn't changing the
2517 * list out from under us. It is probably best to just not try to
2518 * handle threads on other CPU's for now.
2519 */
2520 if (td == curthread && PCPU_GET(spinlocks) != NULL)
2521 witness_list_locks(PCPU_PTR(spinlocks), db_printf);
2522 }
2523
2524 DB_SHOW_COMMAND(locks, db_witness_list)
2525 {
2526 struct thread *td;
2527
2528 if (have_addr)
2529 td = db_lookup_thread(addr, true);
2530 else
2531 td = kdb_thread;
2532 witness_ddb_list(td);
2533 }
2534
2535 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all)
2536 {
2537 struct thread *td;
2538 struct proc *p;
2539
2540 /*
2541 * It would be nice to list only threads and processes that actually
2542 * held sleep locks, but that information is currently not exported
2543 * by WITNESS.
2544 */
2545 FOREACH_PROC_IN_SYSTEM(p) {
2546 if (!witness_proc_has_locks(p))
2547 continue;
2548 FOREACH_THREAD_IN_PROC(p, td) {
2549 if (!witness_thread_has_locks(td))
2550 continue;
2551 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid,
2552 p->p_comm, td, td->td_tid);
2553 witness_ddb_list(td);
2554 if (db_pager_quit)
2555 return;
2556 }
2557 }
2558 }
2559 DB_SHOW_ALIAS(alllocks, db_witness_list_all)
2560
2561 DB_SHOW_COMMAND(witness, db_witness_display)
2562 {
2563
2564 witness_ddb_display(db_printf);
2565 }
2566 #endif
2567
2568 static void
2569 sbuf_print_witness_badstacks(struct sbuf *sb, size_t *oldidx)
2570 {
2571 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2;
2572 struct witness *tmp_w1, *tmp_w2, *w1, *w2;
2573 int generation, i, j;
2574
2575 tmp_data1 = NULL;
2576 tmp_data2 = NULL;
2577 tmp_w1 = NULL;
2578 tmp_w2 = NULL;
2579
2580 /* Allocate and init temporary storage space. */
2581 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
2582 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
2583 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP,
2584 M_WAITOK | M_ZERO);
2585 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP,
2586 M_WAITOK | M_ZERO);
2587 stack_zero(&tmp_data1->wlod_stack);
2588 stack_zero(&tmp_data2->wlod_stack);
2589
2590 restart:
2591 mtx_lock_spin(&w_mtx);
2592 generation = w_generation;
2593 mtx_unlock_spin(&w_mtx);
2594 sbuf_printf(sb, "Number of known direct relationships is %d\n",
2595 w_lohash.wloh_count);
2596 for (i = 1; i < w_max_used_index; i++) {
2597 mtx_lock_spin(&w_mtx);
2598 if (generation != w_generation) {
2599 mtx_unlock_spin(&w_mtx);
2600
2601 /* The graph has changed, try again. */
2602 *oldidx = 0;
2603 sbuf_clear(sb);
2604 goto restart;
2605 }
2606
2607 w1 = &w_data[i];
2608 if (w1->w_reversed == 0) {
2609 mtx_unlock_spin(&w_mtx);
2610 continue;
2611 }
2612
2613 /* Copy w1 locally so we can release the spin lock. */
2614 *tmp_w1 = *w1;
2615 mtx_unlock_spin(&w_mtx);
2616
2617 if (tmp_w1->w_reversed == 0)
2618 continue;
2619 for (j = 1; j < w_max_used_index; j++) {
2620 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j)
2621 continue;
2622
2623 mtx_lock_spin(&w_mtx);
2624 if (generation != w_generation) {
2625 mtx_unlock_spin(&w_mtx);
2626
2627 /* The graph has changed, try again. */
2628 *oldidx = 0;
2629 sbuf_clear(sb);
2630 goto restart;
2631 }
2632
2633 w2 = &w_data[j];
2634 data1 = witness_lock_order_get(w1, w2);
2635 data2 = witness_lock_order_get(w2, w1);
2636
2637 /*
2638 * Copy information locally so we can release the
2639 * spin lock.
2640 */
2641 *tmp_w2 = *w2;
2642
2643 if (data1) {
2644 stack_zero(&tmp_data1->wlod_stack);
2645 stack_copy(&data1->wlod_stack,
2646 &tmp_data1->wlod_stack);
2647 }
2648 if (data2 && data2 != data1) {
2649 stack_zero(&tmp_data2->wlod_stack);
2650 stack_copy(&data2->wlod_stack,
2651 &tmp_data2->wlod_stack);
2652 }
2653 mtx_unlock_spin(&w_mtx);
2654
2655 sbuf_printf(sb,
2656 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n",
2657 tmp_w1->w_name, tmp_w1->w_class->lc_name,
2658 tmp_w2->w_name, tmp_w2->w_class->lc_name);
2659 if (data1) {
2660 sbuf_printf(sb,
2661 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
2662 tmp_w1->w_name, tmp_w1->w_class->lc_name,
2663 tmp_w2->w_name, tmp_w2->w_class->lc_name);
2664 stack_sbuf_print(sb, &tmp_data1->wlod_stack);
2665 sbuf_printf(sb, "\n");
2666 }
2667 if (data2 && data2 != data1) {
2668 sbuf_printf(sb,
2669 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
2670 tmp_w2->w_name, tmp_w2->w_class->lc_name,
2671 tmp_w1->w_name, tmp_w1->w_class->lc_name);
2672 stack_sbuf_print(sb, &tmp_data2->wlod_stack);
2673 sbuf_printf(sb, "\n");
2674 }
2675 }
2676 }
2677 mtx_lock_spin(&w_mtx);
2678 if (generation != w_generation) {
2679 mtx_unlock_spin(&w_mtx);
2680
2681 /*
2682 * The graph changed while we were printing stack data,
2683 * try again.
2684 */
2685 *oldidx = 0;
2686 sbuf_clear(sb);
2687 goto restart;
2688 }
2689 mtx_unlock_spin(&w_mtx);
2690
2691 /* Free temporary storage space. */
2692 free(tmp_data1, M_TEMP);
2693 free(tmp_data2, M_TEMP);
2694 free(tmp_w1, M_TEMP);
2695 free(tmp_w2, M_TEMP);
2696 }
2697
2698 static int
2699 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS)
2700 {
2701 struct sbuf *sb;
2702 int error;
2703
2704 if (witness_watch < 1) {
2705 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
2706 return (error);
2707 }
2708 if (witness_cold) {
2709 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
2710 return (error);
2711 }
2712 error = 0;
2713 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND);
2714 if (sb == NULL)
2715 return (ENOMEM);
2716
2717 sbuf_print_witness_badstacks(sb, &req->oldidx);
2718
2719 sbuf_finish(sb);
2720 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
2721 sbuf_delete(sb);
2722
2723 return (error);
2724 }
2725
2726 #ifdef DDB
2727 static int
2728 sbuf_db_printf_drain(void *arg __unused, const char *data, int len)
2729 {
2730
2731 return (db_printf("%.*s", len, data));
2732 }
2733
2734 DB_SHOW_COMMAND(badstacks, db_witness_badstacks)
2735 {
2736 struct sbuf sb;
2737 char buffer[128];
2738 size_t dummy;
2739
2740 sbuf_new(&sb, buffer, sizeof(buffer), SBUF_FIXEDLEN);
2741 sbuf_set_drain(&sb, sbuf_db_printf_drain, NULL);
2742 sbuf_print_witness_badstacks(&sb, &dummy);
2743 sbuf_finish(&sb);
2744 }
2745 #endif
2746
2747 static int
2748 sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS)
2749 {
2750 static const struct {
2751 enum witness_channel channel;
2752 const char *name;
2753 } channels[] = {
2754 { WITNESS_CONSOLE, "console" },
2755 { WITNESS_LOG, "log" },
2756 { WITNESS_NONE, "none" },
2757 };
2758 char buf[16];
2759 u_int i;
2760 int error;
2761
2762 buf[0] = '\0';
2763 for (i = 0; i < nitems(channels); i++)
2764 if (witness_channel == channels[i].channel) {
2765 snprintf(buf, sizeof(buf), "%s", channels[i].name);
2766 break;
2767 }
2768
2769 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
2770 if (error != 0 || req->newptr == NULL)
2771 return (error);
2772
2773 error = EINVAL;
2774 for (i = 0; i < nitems(channels); i++)
2775 if (strcmp(channels[i].name, buf) == 0) {
2776 witness_channel = channels[i].channel;
2777 error = 0;
2778 break;
2779 }
2780 return (error);
2781 }
2782
2783 static int
2784 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS)
2785 {
2786 struct witness *w;
2787 struct sbuf *sb;
2788 int error;
2789
2790 #ifdef __i386__
2791 error = SYSCTL_OUT(req, w_notallowed, sizeof(w_notallowed));
2792 return (error);
2793 #endif
2794
2795 if (witness_watch < 1) {
2796 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
2797 return (error);
2798 }
2799 if (witness_cold) {
2800 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
2801 return (error);
2802 }
2803 error = 0;
2804
2805 error = sysctl_wire_old_buffer(req, 0);
2806 if (error != 0)
2807 return (error);
2808 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req);
2809 if (sb == NULL)
2810 return (ENOMEM);
2811 sbuf_printf(sb, "\n");
2812
2813 mtx_lock_spin(&w_mtx);
2814 STAILQ_FOREACH(w, &w_all, w_list)
2815 w->w_displayed = 0;
2816 STAILQ_FOREACH(w, &w_all, w_list)
2817 witness_add_fullgraph(sb, w);
2818 mtx_unlock_spin(&w_mtx);
2819
2820 /*
2821 * Close the sbuf and return to userland.
2822 */
2823 error = sbuf_finish(sb);
2824 sbuf_delete(sb);
2825
2826 return (error);
2827 }
2828
2829 static int
2830 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS)
2831 {
2832 int error, value;
2833
2834 value = witness_watch;
2835 error = sysctl_handle_int(oidp, &value, 0, req);
2836 if (error != 0 || req->newptr == NULL)
2837 return (error);
2838 if (value > 1 || value < -1 ||
2839 (witness_watch == -1 && value != witness_watch))
2840 return (EINVAL);
2841 witness_watch = value;
2842 return (0);
2843 }
2844
2845 static void
2846 witness_add_fullgraph(struct sbuf *sb, struct witness *w)
2847 {
2848 int i;
2849
2850 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0))
2851 return;
2852 w->w_displayed = 1;
2853
2854 WITNESS_INDEX_ASSERT(w->w_index);
2855 for (i = 1; i <= w_max_used_index; i++) {
2856 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) {
2857 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name,
2858 w_data[i].w_name);
2859 witness_add_fullgraph(sb, &w_data[i]);
2860 }
2861 }
2862 }
2863
2864 /*
2865 * A simple hash function. Takes a key pointer and a key size. If size == 0,
2866 * interprets the key as a string and reads until the null
2867 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit
2868 * hash value computed from the key.
2869 */
2870 static uint32_t
2871 witness_hash_djb2(const uint8_t *key, uint32_t size)
2872 {
2873 unsigned int hash = 5381;
2874 int i;
2875
2876 /* hash = hash * 33 + key[i] */
2877 if (size)
2878 for (i = 0; i < size; i++)
2879 hash = ((hash << 5) + hash) + (unsigned int)key[i];
2880 else
2881 for (i = 0; key[i] != 0; i++)
2882 hash = ((hash << 5) + hash) + (unsigned int)key[i];
2883
2884 return (hash);
2885 }
2886
2887
2888 /*
2889 * Initializes the two witness hash tables. Called exactly once from
2890 * witness_initialize().
2891 */
2892 static void
2893 witness_init_hash_tables(void)
2894 {
2895 int i;
2896
2897 MPASS(witness_cold);
2898
2899 /* Initialize the hash tables. */
2900 for (i = 0; i < WITNESS_HASH_SIZE; i++)
2901 w_hash.wh_array[i] = NULL;
2902
2903 w_hash.wh_size = WITNESS_HASH_SIZE;
2904 w_hash.wh_count = 0;
2905
2906 /* Initialize the lock order data hash. */
2907 w_lofree = NULL;
2908 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) {
2909 memset(&w_lodata[i], 0, sizeof(w_lodata[i]));
2910 w_lodata[i].wlod_next = w_lofree;
2911 w_lofree = &w_lodata[i];
2912 }
2913 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE;
2914 w_lohash.wloh_count = 0;
2915 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++)
2916 w_lohash.wloh_array[i] = NULL;
2917 }
2918
2919 static struct witness *
2920 witness_hash_get(const char *key)
2921 {
2922 struct witness *w;
2923 uint32_t hash;
2924
2925 MPASS(key != NULL);
2926 if (witness_cold == 0)
2927 mtx_assert(&w_mtx, MA_OWNED);
2928 hash = witness_hash_djb2(key, 0) % w_hash.wh_size;
2929 w = w_hash.wh_array[hash];
2930 while (w != NULL) {
2931 if (strcmp(w->w_name, key) == 0)
2932 goto out;
2933 w = w->w_hash_next;
2934 }
2935
2936 out:
2937 return (w);
2938 }
2939
2940 static void
2941 witness_hash_put(struct witness *w)
2942 {
2943 uint32_t hash;
2944
2945 MPASS(w != NULL);
2946 MPASS(w->w_name != NULL);
2947 if (witness_cold == 0)
2948 mtx_assert(&w_mtx, MA_OWNED);
2949 KASSERT(witness_hash_get(w->w_name) == NULL,
2950 ("%s: trying to add a hash entry that already exists!", __func__));
2951 KASSERT(w->w_hash_next == NULL,
2952 ("%s: w->w_hash_next != NULL", __func__));
2953
2954 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size;
2955 w->w_hash_next = w_hash.wh_array[hash];
2956 w_hash.wh_array[hash] = w;
2957 w_hash.wh_count++;
2958 }
2959
2960
2961 static struct witness_lock_order_data *
2962 witness_lock_order_get(struct witness *parent, struct witness *child)
2963 {
2964 struct witness_lock_order_data *data = NULL;
2965 struct witness_lock_order_key key;
2966 unsigned int hash;
2967
2968 MPASS(parent != NULL && child != NULL);
2969 key.from = parent->w_index;
2970 key.to = child->w_index;
2971 WITNESS_INDEX_ASSERT(key.from);
2972 WITNESS_INDEX_ASSERT(key.to);
2973 if ((w_rmatrix[parent->w_index][child->w_index]
2974 & WITNESS_LOCK_ORDER_KNOWN) == 0)
2975 goto out;
2976
2977 hash = witness_hash_djb2((const char*)&key,
2978 sizeof(key)) % w_lohash.wloh_size;
2979 data = w_lohash.wloh_array[hash];
2980 while (data != NULL) {
2981 if (witness_lock_order_key_equal(&data->wlod_key, &key))
2982 break;
2983 data = data->wlod_next;
2984 }
2985
2986 out:
2987 return (data);
2988 }
2989
2990 /*
2991 * Verify that parent and child have a known relationship, are not the same,
2992 * and child is actually a child of parent. This is done without w_mtx
2993 * to avoid contention in the common case.
2994 */
2995 static int
2996 witness_lock_order_check(struct witness *parent, struct witness *child)
2997 {
2998
2999 if (parent != child &&
3000 w_rmatrix[parent->w_index][child->w_index]
3001 & WITNESS_LOCK_ORDER_KNOWN &&
3002 isitmychild(parent, child))
3003 return (1);
3004
3005 return (0);
3006 }
3007
3008 static int
3009 witness_lock_order_add(struct witness *parent, struct witness *child)
3010 {
3011 struct witness_lock_order_data *data = NULL;
3012 struct witness_lock_order_key key;
3013 unsigned int hash;
3014
3015 MPASS(parent != NULL && child != NULL);
3016 key.from = parent->w_index;
3017 key.to = child->w_index;
3018 WITNESS_INDEX_ASSERT(key.from);
3019 WITNESS_INDEX_ASSERT(key.to);
3020 if (w_rmatrix[parent->w_index][child->w_index]
3021 & WITNESS_LOCK_ORDER_KNOWN)
3022 return (1);
3023
3024 hash = witness_hash_djb2((const char*)&key,
3025 sizeof(key)) % w_lohash.wloh_size;
3026 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN;
3027 data = w_lofree;
3028 if (data == NULL)
3029 return (0);
3030 w_lofree = data->wlod_next;
3031 data->wlod_next = w_lohash.wloh_array[hash];
3032 data->wlod_key = key;
3033 w_lohash.wloh_array[hash] = data;
3034 w_lohash.wloh_count++;
3035 stack_zero(&data->wlod_stack);
3036 stack_save(&data->wlod_stack);
3037 return (1);
3038 }
3039
3040 /* Call this whenever the structure of the witness graph changes. */
3041 static void
3042 witness_increment_graph_generation(void)
3043 {
3044
3045 if (witness_cold == 0)
3046 mtx_assert(&w_mtx, MA_OWNED);
3047 w_generation++;
3048 }
3049
3050 static int
3051 witness_output_drain(void *arg __unused, const char *data, int len)
3052 {
3053
3054 witness_output("%.*s", len, data);
3055 return (len);
3056 }
3057
3058 static void
3059 witness_debugger(int cond, const char *msg)
3060 {
3061 char buf[32];
3062 struct sbuf sb;
3063 struct stack st;
3064
3065 if (!cond)
3066 return;
3067
3068 if (witness_trace) {
3069 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN);
3070 sbuf_set_drain(&sb, witness_output_drain, NULL);
3071
3072 stack_zero(&st);
3073 stack_save(&st);
3074 witness_output("stack backtrace:\n");
3075 stack_sbuf_print_ddb(&sb, &st);
3076
3077 sbuf_finish(&sb);
3078 }
3079
3080 #ifdef KDB
3081 if (witness_kdb)
3082 kdb_enter(KDB_WHY_WITNESS, msg);
3083 #endif
3084 }
Cache object: f55179070f7953cf02e057a97ffbcaa3
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