1 /*-
2 * Copyright (c) 2008 Isilon Systems, Inc.
3 * Copyright (c) 2008 Ilya Maykov <ivmaykov@gmail.com>
4 * Copyright (c) 1998 Berkeley Software Design, Inc.
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Berkeley Software Design Inc's name may not be used to endorse or
16 * promote products derived from this software without specific prior
17 * written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 *
31 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $
32 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $
33 */
34
35 /*
36 * Implementation of the `witness' lock verifier. Originally implemented for
37 * mutexes in BSD/OS. Extended to handle generic lock objects and lock
38 * classes in FreeBSD.
39 */
40
41 /*
42 * Main Entry: witness
43 * Pronunciation: 'wit-n&s
44 * Function: noun
45 * Etymology: Middle English witnesse, from Old English witnes knowledge,
46 * testimony, witness, from 2wit
47 * Date: before 12th century
48 * 1 : attestation of a fact or event : TESTIMONY
49 * 2 : one that gives evidence; specifically : one who testifies in
50 * a cause or before a judicial tribunal
51 * 3 : one asked to be present at a transaction so as to be able to
52 * testify to its having taken place
53 * 4 : one who has personal knowledge of something
54 * 5 a : something serving as evidence or proof : SIGN
55 * b : public affirmation by word or example of usually
56 * religious faith or conviction <the heroic witness to divine
57 * life -- Pilot>
58 * 6 capitalized : a member of the Jehovah's Witnesses
59 */
60
61 /*
62 * Special rules concerning Giant and lock orders:
63 *
64 * 1) Giant must be acquired before any other mutexes. Stated another way,
65 * no other mutex may be held when Giant is acquired.
66 *
67 * 2) Giant must be released when blocking on a sleepable lock.
68 *
69 * This rule is less obvious, but is a result of Giant providing the same
70 * semantics as spl(). Basically, when a thread sleeps, it must release
71 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule
72 * 2).
73 *
74 * 3) Giant may be acquired before or after sleepable locks.
75 *
76 * This rule is also not quite as obvious. Giant may be acquired after
77 * a sleepable lock because it is a non-sleepable lock and non-sleepable
78 * locks may always be acquired while holding a sleepable lock. The second
79 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose
80 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1
81 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and
82 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to
83 * execute. Thus, acquiring Giant both before and after a sleepable lock
84 * will not result in a lock order reversal.
85 */
86
87 #include <sys/cdefs.h>
88 __FBSDID("$FreeBSD$");
89
90 #include "opt_ddb.h"
91 #include "opt_hwpmc_hooks.h"
92 #include "opt_stack.h"
93 #include "opt_witness.h"
94
95 #include <sys/param.h>
96 #include <sys/bus.h>
97 #include <sys/kdb.h>
98 #include <sys/kernel.h>
99 #include <sys/ktr.h>
100 #include <sys/lock.h>
101 #include <sys/malloc.h>
102 #include <sys/mutex.h>
103 #include <sys/priv.h>
104 #include <sys/proc.h>
105 #include <sys/sbuf.h>
106 #include <sys/sched.h>
107 #include <sys/stack.h>
108 #include <sys/sysctl.h>
109 #include <sys/systm.h>
110
111 #ifdef DDB
112 #include <ddb/ddb.h>
113 #endif
114
115 #include <machine/stdarg.h>
116
117 #if !defined(DDB) && !defined(STACK)
118 #error "DDB or STACK options are required for WITNESS"
119 #endif
120
121 /* Note that these traces do not work with KTR_ALQ. */
122 #if 0
123 #define KTR_WITNESS KTR_SUBSYS
124 #else
125 #define KTR_WITNESS 0
126 #endif
127
128 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */
129 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */
130 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */
131
132 /* Define this to check for blessed mutexes */
133 #undef BLESSING
134
135 #define WITNESS_COUNT 1024
136 #define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4)
137 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */
138 #define WITNESS_PENDLIST (1024 + MAXCPU)
139
140 /* Allocate 256 KB of stack data space */
141 #define WITNESS_LO_DATA_COUNT 2048
142
143 /* Prime, gives load factor of ~2 at full load */
144 #define WITNESS_LO_HASH_SIZE 1021
145
146 /*
147 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads
148 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should
149 * probably be safe for the most part, but it's still a SWAG.
150 */
151 #define LOCK_NCHILDREN 5
152 #define LOCK_CHILDCOUNT 2048
153
154 #define MAX_W_NAME 64
155
156 #define BADSTACK_SBUF_SIZE (256 * WITNESS_COUNT)
157 #define FULLGRAPH_SBUF_SIZE 512
158
159 /*
160 * These flags go in the witness relationship matrix and describe the
161 * relationship between any two struct witness objects.
162 */
163 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */
164 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */
165 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */
166 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */
167 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */
168 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR)
169 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT)
170 #define WITNESS_RELATED_MASK \
171 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK)
172 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been
173 * observed. */
174 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */
175 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */
176 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */
177
178 /* Descendant to ancestor flags */
179 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2)
180
181 /* Ancestor to descendant flags */
182 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2)
183
184 #define WITNESS_INDEX_ASSERT(i) \
185 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < WITNESS_COUNT)
186
187 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness");
188
189 /*
190 * Lock instances. A lock instance is the data associated with a lock while
191 * it is held by witness. For example, a lock instance will hold the
192 * recursion count of a lock. Lock instances are held in lists. Spin locks
193 * are held in a per-cpu list while sleep locks are held in per-thread list.
194 */
195 struct lock_instance {
196 struct lock_object *li_lock;
197 const char *li_file;
198 int li_line;
199 u_int li_flags;
200 };
201
202 /*
203 * A simple list type used to build the list of locks held by a thread
204 * or CPU. We can't simply embed the list in struct lock_object since a
205 * lock may be held by more than one thread if it is a shared lock. Locks
206 * are added to the head of the list, so we fill up each list entry from
207 * "the back" logically. To ease some of the arithmetic, we actually fill
208 * in each list entry the normal way (children[0] then children[1], etc.) but
209 * when we traverse the list we read children[count-1] as the first entry
210 * down to children[0] as the final entry.
211 */
212 struct lock_list_entry {
213 struct lock_list_entry *ll_next;
214 struct lock_instance ll_children[LOCK_NCHILDREN];
215 u_int ll_count;
216 };
217
218 /*
219 * The main witness structure. One of these per named lock type in the system
220 * (for example, "vnode interlock").
221 */
222 struct witness {
223 char w_name[MAX_W_NAME];
224 uint32_t w_index; /* Index in the relationship matrix */
225 struct lock_class *w_class;
226 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */
227 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */
228 struct witness *w_hash_next; /* Linked list in hash buckets. */
229 const char *w_file; /* File where last acquired */
230 uint32_t w_line; /* Line where last acquired */
231 uint32_t w_refcount;
232 uint16_t w_num_ancestors; /* direct/indirect
233 * ancestor count */
234 uint16_t w_num_descendants; /* direct/indirect
235 * descendant count */
236 int16_t w_ddb_level;
237 unsigned w_displayed:1;
238 unsigned w_reversed:1;
239 };
240
241 STAILQ_HEAD(witness_list, witness);
242
243 /*
244 * The witness hash table. Keys are witness names (const char *), elements are
245 * witness objects (struct witness *).
246 */
247 struct witness_hash {
248 struct witness *wh_array[WITNESS_HASH_SIZE];
249 uint32_t wh_size;
250 uint32_t wh_count;
251 };
252
253 /*
254 * Key type for the lock order data hash table.
255 */
256 struct witness_lock_order_key {
257 uint16_t from;
258 uint16_t to;
259 };
260
261 struct witness_lock_order_data {
262 struct stack wlod_stack;
263 struct witness_lock_order_key wlod_key;
264 struct witness_lock_order_data *wlod_next;
265 };
266
267 /*
268 * The witness lock order data hash table. Keys are witness index tuples
269 * (struct witness_lock_order_key), elements are lock order data objects
270 * (struct witness_lock_order_data).
271 */
272 struct witness_lock_order_hash {
273 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE];
274 u_int wloh_size;
275 u_int wloh_count;
276 };
277
278 #ifdef BLESSING
279 struct witness_blessed {
280 const char *b_lock1;
281 const char *b_lock2;
282 };
283 #endif
284
285 struct witness_pendhelp {
286 const char *wh_type;
287 struct lock_object *wh_lock;
288 };
289
290 struct witness_order_list_entry {
291 const char *w_name;
292 struct lock_class *w_class;
293 };
294
295 /*
296 * Returns 0 if one of the locks is a spin lock and the other is not.
297 * Returns 1 otherwise.
298 */
299 static __inline int
300 witness_lock_type_equal(struct witness *w1, struct witness *w2)
301 {
302
303 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) ==
304 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)));
305 }
306
307 static __inline int
308 witness_lock_order_key_equal(const struct witness_lock_order_key *a,
309 const struct witness_lock_order_key *b)
310 {
311
312 return (a->from == b->from && a->to == b->to);
313 }
314
315 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask,
316 const char *fname);
317 #ifdef KDB
318 static void _witness_debugger(int cond, const char *msg);
319 #endif
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 void witness_add_fullgraph(struct sbuf *sb, struct witness *parent);
336 #ifdef DDB
337 static void witness_ddb_compute_levels(void);
338 static void witness_ddb_display(int(*)(const char *fmt, ...));
339 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...),
340 struct witness *, int indent);
341 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...),
342 struct witness_list *list);
343 static void witness_ddb_level_descendants(struct witness *parent, int l);
344 static void witness_ddb_list(struct thread *td);
345 #endif
346 static void witness_free(struct witness *m);
347 static struct witness *witness_get(void);
348 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size);
349 static struct witness *witness_hash_get(const char *key);
350 static void witness_hash_put(struct witness *w);
351 static void witness_init_hash_tables(void);
352 static void witness_increment_graph_generation(void);
353 static void witness_lock_list_free(struct lock_list_entry *lle);
354 static struct lock_list_entry *witness_lock_list_get(void);
355 static int witness_lock_order_add(struct witness *parent,
356 struct witness *child);
357 static int witness_lock_order_check(struct witness *parent,
358 struct witness *child);
359 static struct witness_lock_order_data *witness_lock_order_get(
360 struct witness *parent,
361 struct witness *child);
362 static void witness_list_lock(struct lock_instance *instance,
363 int (*prnt)(const char *fmt, ...));
364 static void witness_setflag(struct lock_object *lock, int flag, int set);
365
366 #ifdef KDB
367 #define witness_debugger(c) _witness_debugger(c, __func__)
368 #else
369 #define witness_debugger(c)
370 #endif
371
372 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL,
373 "Witness Locking");
374
375 /*
376 * If set to 0, lock order checking is disabled. If set to -1,
377 * witness is completely disabled. Otherwise witness performs full
378 * lock order checking for all locks. At runtime, lock order checking
379 * may be toggled. However, witness cannot be reenabled once it is
380 * completely disabled.
381 */
382 static int witness_watch = 1;
383 TUNABLE_INT("debug.witness.watch", &witness_watch);
384 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0,
385 sysctl_debug_witness_watch, "I", "witness is watching lock operations");
386
387 #ifdef KDB
388 /*
389 * When KDB is enabled and witness_kdb is 1, it will cause the system
390 * to drop into kdebug() when:
391 * - a lock hierarchy violation occurs
392 * - locks are held when going to sleep.
393 */
394 #ifdef WITNESS_KDB
395 int witness_kdb = 1;
396 #else
397 int witness_kdb = 0;
398 #endif
399 TUNABLE_INT("debug.witness.kdb", &witness_kdb);
400 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, "");
401
402 /*
403 * When KDB is enabled and witness_trace is 1, it will cause the system
404 * to print a stack trace:
405 * - a lock hierarchy violation occurs
406 * - locks are held when going to sleep.
407 */
408 int witness_trace = 1;
409 TUNABLE_INT("debug.witness.trace", &witness_trace);
410 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, "");
411 #endif /* KDB */
412
413 #ifdef WITNESS_SKIPSPIN
414 int witness_skipspin = 1;
415 #else
416 int witness_skipspin = 0;
417 #endif
418 TUNABLE_INT("debug.witness.skipspin", &witness_skipspin);
419 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin,
420 0, "");
421
422 /*
423 * Call this to print out the relations between locks.
424 */
425 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD,
426 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs");
427
428 /*
429 * Call this to print out the witness faulty stacks.
430 */
431 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD,
432 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks");
433
434 static struct mtx w_mtx;
435
436 /* w_list */
437 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free);
438 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all);
439
440 /* w_typelist */
441 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin);
442 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep);
443
444 /* lock list */
445 static struct lock_list_entry *w_lock_list_free = NULL;
446 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST];
447 static u_int pending_cnt;
448
449 static int w_free_cnt, w_spin_cnt, w_sleep_cnt;
450 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, "");
451 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, "");
452 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0,
453 "");
454
455 static struct witness *w_data;
456 static uint8_t w_rmatrix[WITNESS_COUNT+1][WITNESS_COUNT+1];
457 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT];
458 static struct witness_hash w_hash; /* The witness hash table. */
459
460 /* The lock order data hash */
461 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT];
462 static struct witness_lock_order_data *w_lofree = NULL;
463 static struct witness_lock_order_hash w_lohash;
464 static int w_max_used_index = 0;
465 static unsigned int w_generation = 0;
466 static const char w_notrunning[] = "Witness not running\n";
467 static const char w_stillcold[] = "Witness is still cold\n";
468
469
470 static struct witness_order_list_entry order_lists[] = {
471 /*
472 * sx locks
473 */
474 { "proctree", &lock_class_sx },
475 { "allproc", &lock_class_sx },
476 { "allprison", &lock_class_sx },
477 { NULL, NULL },
478 /*
479 * Various mutexes
480 */
481 { "Giant", &lock_class_mtx_sleep },
482 { "pipe mutex", &lock_class_mtx_sleep },
483 { "sigio lock", &lock_class_mtx_sleep },
484 { "process group", &lock_class_mtx_sleep },
485 { "process lock", &lock_class_mtx_sleep },
486 { "session", &lock_class_mtx_sleep },
487 { "uidinfo hash", &lock_class_rw },
488 #ifdef HWPMC_HOOKS
489 { "pmc-sleep", &lock_class_mtx_sleep },
490 #endif
491 { "time lock", &lock_class_mtx_sleep },
492 { NULL, NULL },
493 /*
494 * umtx
495 */
496 { "umtx lock", &lock_class_mtx_sleep },
497 { NULL, NULL },
498 /*
499 * Sockets
500 */
501 { "accept", &lock_class_mtx_sleep },
502 { "so_snd", &lock_class_mtx_sleep },
503 { "so_rcv", &lock_class_mtx_sleep },
504 { "sellck", &lock_class_mtx_sleep },
505 { NULL, NULL },
506 /*
507 * Routing
508 */
509 { "so_rcv", &lock_class_mtx_sleep },
510 { "radix node head", &lock_class_rw },
511 { "rtentry", &lock_class_mtx_sleep },
512 { "ifaddr", &lock_class_mtx_sleep },
513 { NULL, NULL },
514 /*
515 * IPv4 multicast:
516 * protocol locks before interface locks, after UDP locks.
517 */
518 { "udpinp", &lock_class_rw },
519 { "in_multi_mtx", &lock_class_mtx_sleep },
520 { "igmp_mtx", &lock_class_mtx_sleep },
521 { "if_addr_lock", &lock_class_rw },
522 { NULL, NULL },
523 /*
524 * IPv6 multicast:
525 * protocol locks before interface locks, after UDP locks.
526 */
527 { "udpinp", &lock_class_rw },
528 { "in6_multi_mtx", &lock_class_mtx_sleep },
529 { "mld_mtx", &lock_class_mtx_sleep },
530 { "if_addr_lock", &lock_class_rw },
531 { NULL, NULL },
532 /*
533 * UNIX Domain Sockets
534 */
535 { "unp_link_rwlock", &lock_class_rw },
536 { "unp_list_lock", &lock_class_mtx_sleep },
537 { "unp", &lock_class_mtx_sleep },
538 { "so_snd", &lock_class_mtx_sleep },
539 { NULL, NULL },
540 /*
541 * UDP/IP
542 */
543 { "udp", &lock_class_rw },
544 { "udpinp", &lock_class_rw },
545 { "so_snd", &lock_class_mtx_sleep },
546 { NULL, NULL },
547 /*
548 * TCP/IP
549 */
550 { "tcp", &lock_class_rw },
551 { "tcpinp", &lock_class_rw },
552 { "so_snd", &lock_class_mtx_sleep },
553 { NULL, NULL },
554 /*
555 * netatalk
556 */
557 { "ddp_list_mtx", &lock_class_mtx_sleep },
558 { "ddp_mtx", &lock_class_mtx_sleep },
559 { NULL, NULL },
560 /*
561 * BPF
562 */
563 { "bpf global lock", &lock_class_mtx_sleep },
564 { "bpf interface lock", &lock_class_rw },
565 { "bpf cdev lock", &lock_class_mtx_sleep },
566 { NULL, NULL },
567 /*
568 * NFS server
569 */
570 { "nfsd_mtx", &lock_class_mtx_sleep },
571 { "so_snd", &lock_class_mtx_sleep },
572 { NULL, NULL },
573
574 /*
575 * IEEE 802.11
576 */
577 { "802.11 com lock", &lock_class_mtx_sleep},
578 { NULL, NULL },
579 /*
580 * Network drivers
581 */
582 { "network driver", &lock_class_mtx_sleep},
583 { NULL, NULL },
584
585 /*
586 * Netgraph
587 */
588 { "ng_node", &lock_class_mtx_sleep },
589 { "ng_worklist", &lock_class_mtx_sleep },
590 { NULL, NULL },
591 /*
592 * CDEV
593 */
594 { "vm map (system)", &lock_class_mtx_sleep },
595 { "vm pagequeue", &lock_class_mtx_sleep },
596 { "vnode interlock", &lock_class_mtx_sleep },
597 { "cdev", &lock_class_mtx_sleep },
598 { NULL, NULL },
599 /*
600 * VM
601 */
602 { "vm map (user)", &lock_class_sx },
603 { "vm object", &lock_class_rw },
604 { "vm page", &lock_class_mtx_sleep },
605 { "vm pagequeue", &lock_class_mtx_sleep },
606 { "pmap pv global", &lock_class_rw },
607 { "pmap", &lock_class_mtx_sleep },
608 { "pmap pv list", &lock_class_rw },
609 { "vm page free queue", &lock_class_mtx_sleep },
610 { NULL, NULL },
611 /*
612 * kqueue/VFS interaction
613 */
614 { "kqueue", &lock_class_mtx_sleep },
615 { "struct mount mtx", &lock_class_mtx_sleep },
616 { "vnode interlock", &lock_class_mtx_sleep },
617 { NULL, NULL },
618 /*
619 * ZFS locking
620 */
621 { "dn->dn_mtx", &lock_class_sx },
622 { "dr->dt.di.dr_mtx", &lock_class_sx },
623 { "db->db_mtx", &lock_class_sx },
624 { NULL, NULL },
625 /*
626 * spin locks
627 */
628 #ifdef SMP
629 { "ap boot", &lock_class_mtx_spin },
630 #endif
631 { "rm.mutex_mtx", &lock_class_mtx_spin },
632 { "sio", &lock_class_mtx_spin },
633 { "scrlock", &lock_class_mtx_spin },
634 #ifdef __i386__
635 { "cy", &lock_class_mtx_spin },
636 #endif
637 #ifdef __sparc64__
638 { "pcib_mtx", &lock_class_mtx_spin },
639 { "rtc_mtx", &lock_class_mtx_spin },
640 #endif
641 { "scc_hwmtx", &lock_class_mtx_spin },
642 { "uart_hwmtx", &lock_class_mtx_spin },
643 { "fast_taskqueue", &lock_class_mtx_spin },
644 { "intr table", &lock_class_mtx_spin },
645 #ifdef HWPMC_HOOKS
646 { "pmc-per-proc", &lock_class_mtx_spin },
647 #endif
648 { "process slock", &lock_class_mtx_spin },
649 { "sleepq chain", &lock_class_mtx_spin },
650 { "rm_spinlock", &lock_class_mtx_spin },
651 { "turnstile chain", &lock_class_mtx_spin },
652 { "turnstile lock", &lock_class_mtx_spin },
653 { "sched lock", &lock_class_mtx_spin },
654 { "td_contested", &lock_class_mtx_spin },
655 { "callout", &lock_class_mtx_spin },
656 { "entropy harvest mutex", &lock_class_mtx_spin },
657 { "syscons video lock", &lock_class_mtx_spin },
658 #ifdef SMP
659 { "smp rendezvous", &lock_class_mtx_spin },
660 #endif
661 #ifdef __powerpc__
662 { "tlb0", &lock_class_mtx_spin },
663 #endif
664 /*
665 * leaf locks
666 */
667 { "intrcnt", &lock_class_mtx_spin },
668 { "icu", &lock_class_mtx_spin },
669 #if defined(SMP) && defined(__sparc64__)
670 { "ipi", &lock_class_mtx_spin },
671 #endif
672 #ifdef __i386__
673 { "allpmaps", &lock_class_mtx_spin },
674 { "descriptor tables", &lock_class_mtx_spin },
675 #endif
676 { "clk", &lock_class_mtx_spin },
677 { "cpuset", &lock_class_mtx_spin },
678 { "mprof lock", &lock_class_mtx_spin },
679 { "zombie lock", &lock_class_mtx_spin },
680 { "ALD Queue", &lock_class_mtx_spin },
681 #ifdef __ia64__
682 { "MCA spin lock", &lock_class_mtx_spin },
683 #endif
684 #if defined(__i386__) || defined(__amd64__)
685 { "pcicfg", &lock_class_mtx_spin },
686 { "NDIS thread lock", &lock_class_mtx_spin },
687 #endif
688 { "tw_osl_io_lock", &lock_class_mtx_spin },
689 { "tw_osl_q_lock", &lock_class_mtx_spin },
690 { "tw_cl_io_lock", &lock_class_mtx_spin },
691 { "tw_cl_intr_lock", &lock_class_mtx_spin },
692 { "tw_cl_gen_lock", &lock_class_mtx_spin },
693 #ifdef HWPMC_HOOKS
694 { "pmc-leaf", &lock_class_mtx_spin },
695 #endif
696 { "blocked lock", &lock_class_mtx_spin },
697 { NULL, NULL },
698 { NULL, NULL }
699 };
700
701 #ifdef BLESSING
702 /*
703 * Pairs of locks which have been blessed
704 * Don't complain about order problems with blessed locks
705 */
706 static struct witness_blessed blessed_list[] = {
707 };
708 static int blessed_count =
709 sizeof(blessed_list) / sizeof(struct witness_blessed);
710 #endif
711
712 /*
713 * This global is set to 0 once it becomes safe to use the witness code.
714 */
715 static int witness_cold = 1;
716
717 /*
718 * This global is set to 1 once the static lock orders have been enrolled
719 * so that a warning can be issued for any spin locks enrolled later.
720 */
721 static int witness_spin_warn = 0;
722
723 /* Trim useless garbage from filenames. */
724 static const char *
725 fixup_filename(const char *file)
726 {
727
728 if (file == NULL)
729 return (NULL);
730 while (strncmp(file, "../", 3) == 0)
731 file += 3;
732 return (file);
733 }
734
735 /*
736 * The WITNESS-enabled diagnostic code. Note that the witness code does
737 * assume that the early boot is single-threaded at least until after this
738 * routine is completed.
739 */
740 static void
741 witness_initialize(void *dummy __unused)
742 {
743 struct lock_object *lock;
744 struct witness_order_list_entry *order;
745 struct witness *w, *w1;
746 int i;
747
748 w_data = malloc(sizeof (struct witness) * WITNESS_COUNT, M_WITNESS,
749 M_NOWAIT | M_ZERO);
750
751 /*
752 * We have to release Giant before initializing its witness
753 * structure so that WITNESS doesn't get confused.
754 */
755 mtx_unlock(&Giant);
756 mtx_assert(&Giant, MA_NOTOWNED);
757
758 CTR1(KTR_WITNESS, "%s: initializing witness", __func__);
759 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET |
760 MTX_NOWITNESS | MTX_NOPROFILE);
761 for (i = WITNESS_COUNT - 1; i >= 0; i--) {
762 w = &w_data[i];
763 memset(w, 0, sizeof(*w));
764 w_data[i].w_index = i; /* Witness index never changes. */
765 witness_free(w);
766 }
767 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0,
768 ("%s: Invalid list of free witness objects", __func__));
769
770 /* Witness with index 0 is not used to aid in debugging. */
771 STAILQ_REMOVE_HEAD(&w_free, w_list);
772 w_free_cnt--;
773
774 memset(w_rmatrix, 0,
775 (sizeof(**w_rmatrix) * (WITNESS_COUNT+1) * (WITNESS_COUNT+1)));
776
777 for (i = 0; i < LOCK_CHILDCOUNT; i++)
778 witness_lock_list_free(&w_locklistdata[i]);
779 witness_init_hash_tables();
780
781 /* First add in all the specified order lists. */
782 for (order = order_lists; order->w_name != NULL; order++) {
783 w = enroll(order->w_name, order->w_class);
784 if (w == NULL)
785 continue;
786 w->w_file = "order list";
787 for (order++; order->w_name != NULL; order++) {
788 w1 = enroll(order->w_name, order->w_class);
789 if (w1 == NULL)
790 continue;
791 w1->w_file = "order list";
792 itismychild(w, w1);
793 w = w1;
794 }
795 }
796 witness_spin_warn = 1;
797
798 /* Iterate through all locks and add them to witness. */
799 for (i = 0; pending_locks[i].wh_lock != NULL; i++) {
800 lock = pending_locks[i].wh_lock;
801 KASSERT(lock->lo_flags & LO_WITNESS,
802 ("%s: lock %s is on pending list but not LO_WITNESS",
803 __func__, lock->lo_name));
804 lock->lo_witness = enroll(pending_locks[i].wh_type,
805 LOCK_CLASS(lock));
806 }
807
808 /* Mark the witness code as being ready for use. */
809 witness_cold = 0;
810
811 mtx_lock(&Giant);
812 }
813 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize,
814 NULL);
815
816 void
817 witness_init(struct lock_object *lock, const char *type)
818 {
819 struct lock_class *class;
820
821 /* Various sanity checks. */
822 class = LOCK_CLASS(lock);
823 if ((lock->lo_flags & LO_RECURSABLE) != 0 &&
824 (class->lc_flags & LC_RECURSABLE) == 0)
825 kassert_panic("%s: lock (%s) %s can not be recursable",
826 __func__, class->lc_name, lock->lo_name);
827 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
828 (class->lc_flags & LC_SLEEPABLE) == 0)
829 kassert_panic("%s: lock (%s) %s can not be sleepable",
830 __func__, class->lc_name, lock->lo_name);
831 if ((lock->lo_flags & LO_UPGRADABLE) != 0 &&
832 (class->lc_flags & LC_UPGRADABLE) == 0)
833 kassert_panic("%s: lock (%s) %s can not be upgradable",
834 __func__, class->lc_name, lock->lo_name);
835
836 /*
837 * If we shouldn't watch this lock, then just clear lo_witness.
838 * Otherwise, if witness_cold is set, then it is too early to
839 * enroll this lock, so defer it to witness_initialize() by adding
840 * it to the pending_locks list. If it is not too early, then enroll
841 * the lock now.
842 */
843 if (witness_watch < 1 || panicstr != NULL ||
844 (lock->lo_flags & LO_WITNESS) == 0)
845 lock->lo_witness = NULL;
846 else if (witness_cold) {
847 pending_locks[pending_cnt].wh_lock = lock;
848 pending_locks[pending_cnt++].wh_type = type;
849 if (pending_cnt > WITNESS_PENDLIST)
850 panic("%s: pending locks list is too small, "
851 "increase WITNESS_PENDLIST\n",
852 __func__);
853 } else
854 lock->lo_witness = enroll(type, class);
855 }
856
857 void
858 witness_destroy(struct lock_object *lock)
859 {
860 struct lock_class *class;
861 struct witness *w;
862
863 class = LOCK_CLASS(lock);
864
865 if (witness_cold)
866 panic("lock (%s) %s destroyed while witness_cold",
867 class->lc_name, lock->lo_name);
868
869 /* XXX: need to verify that no one holds the lock */
870 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL)
871 return;
872 w = lock->lo_witness;
873
874 mtx_lock_spin(&w_mtx);
875 MPASS(w->w_refcount > 0);
876 w->w_refcount--;
877
878 if (w->w_refcount == 0)
879 depart(w);
880 mtx_unlock_spin(&w_mtx);
881 }
882
883 #ifdef DDB
884 static void
885 witness_ddb_compute_levels(void)
886 {
887 struct witness *w;
888
889 /*
890 * First clear all levels.
891 */
892 STAILQ_FOREACH(w, &w_all, w_list)
893 w->w_ddb_level = -1;
894
895 /*
896 * Look for locks with no parents and level all their descendants.
897 */
898 STAILQ_FOREACH(w, &w_all, w_list) {
899
900 /* If the witness has ancestors (is not a root), skip it. */
901 if (w->w_num_ancestors > 0)
902 continue;
903 witness_ddb_level_descendants(w, 0);
904 }
905 }
906
907 static void
908 witness_ddb_level_descendants(struct witness *w, int l)
909 {
910 int i;
911
912 if (w->w_ddb_level >= l)
913 return;
914
915 w->w_ddb_level = l;
916 l++;
917
918 for (i = 1; i <= w_max_used_index; i++) {
919 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT)
920 witness_ddb_level_descendants(&w_data[i], l);
921 }
922 }
923
924 static void
925 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...),
926 struct witness *w, int indent)
927 {
928 int i;
929
930 for (i = 0; i < indent; i++)
931 prnt(" ");
932 prnt("%s (type: %s, depth: %d, active refs: %d)",
933 w->w_name, w->w_class->lc_name,
934 w->w_ddb_level, w->w_refcount);
935 if (w->w_displayed) {
936 prnt(" -- (already displayed)\n");
937 return;
938 }
939 w->w_displayed = 1;
940 if (w->w_file != NULL && w->w_line != 0)
941 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file),
942 w->w_line);
943 else
944 prnt(" -- never acquired\n");
945 indent++;
946 WITNESS_INDEX_ASSERT(w->w_index);
947 for (i = 1; i <= w_max_used_index; i++) {
948 if (db_pager_quit)
949 return;
950 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT)
951 witness_ddb_display_descendants(prnt, &w_data[i],
952 indent);
953 }
954 }
955
956 static void
957 witness_ddb_display_list(int(*prnt)(const char *fmt, ...),
958 struct witness_list *list)
959 {
960 struct witness *w;
961
962 STAILQ_FOREACH(w, list, w_typelist) {
963 if (w->w_file == NULL || w->w_ddb_level > 0)
964 continue;
965
966 /* This lock has no anscestors - display its descendants. */
967 witness_ddb_display_descendants(prnt, w, 0);
968 if (db_pager_quit)
969 return;
970 }
971 }
972
973 static void
974 witness_ddb_display(int(*prnt)(const char *fmt, ...))
975 {
976 struct witness *w;
977
978 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
979 witness_ddb_compute_levels();
980
981 /* Clear all the displayed flags. */
982 STAILQ_FOREACH(w, &w_all, w_list)
983 w->w_displayed = 0;
984
985 /*
986 * First, handle sleep locks which have been acquired at least
987 * once.
988 */
989 prnt("Sleep locks:\n");
990 witness_ddb_display_list(prnt, &w_sleep);
991 if (db_pager_quit)
992 return;
993
994 /*
995 * Now do spin locks which have been acquired at least once.
996 */
997 prnt("\nSpin locks:\n");
998 witness_ddb_display_list(prnt, &w_spin);
999 if (db_pager_quit)
1000 return;
1001
1002 /*
1003 * Finally, any locks which have not been acquired yet.
1004 */
1005 prnt("\nLocks which were never acquired:\n");
1006 STAILQ_FOREACH(w, &w_all, w_list) {
1007 if (w->w_file != NULL || w->w_refcount == 0)
1008 continue;
1009 prnt("%s (type: %s, depth: %d)\n", w->w_name,
1010 w->w_class->lc_name, w->w_ddb_level);
1011 if (db_pager_quit)
1012 return;
1013 }
1014 }
1015 #endif /* DDB */
1016
1017 int
1018 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2)
1019 {
1020
1021 if (witness_watch == -1 || panicstr != NULL)
1022 return (0);
1023
1024 /* Require locks that witness knows about. */
1025 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL ||
1026 lock2->lo_witness == NULL)
1027 return (EINVAL);
1028
1029 mtx_assert(&w_mtx, MA_NOTOWNED);
1030 mtx_lock_spin(&w_mtx);
1031
1032 /*
1033 * If we already have either an explicit or implied lock order that
1034 * is the other way around, then return an error.
1035 */
1036 if (witness_watch &&
1037 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) {
1038 mtx_unlock_spin(&w_mtx);
1039 return (EDOOFUS);
1040 }
1041
1042 /* Try to add the new order. */
1043 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
1044 lock2->lo_witness->w_name, lock1->lo_witness->w_name);
1045 itismychild(lock1->lo_witness, lock2->lo_witness);
1046 mtx_unlock_spin(&w_mtx);
1047 return (0);
1048 }
1049
1050 void
1051 witness_checkorder(struct lock_object *lock, int flags, const char *file,
1052 int line, struct lock_object *interlock)
1053 {
1054 struct lock_list_entry *lock_list, *lle;
1055 struct lock_instance *lock1, *lock2, *plock;
1056 struct lock_class *class, *iclass;
1057 struct witness *w, *w1;
1058 struct thread *td;
1059 int i, j;
1060
1061 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL ||
1062 panicstr != NULL)
1063 return;
1064
1065 w = lock->lo_witness;
1066 class = LOCK_CLASS(lock);
1067 td = curthread;
1068
1069 if (class->lc_flags & LC_SLEEPLOCK) {
1070
1071 /*
1072 * Since spin locks include a critical section, this check
1073 * implicitly enforces a lock order of all sleep locks before
1074 * all spin locks.
1075 */
1076 if (td->td_critnest != 0 && !kdb_active)
1077 kassert_panic("acquiring blockable sleep lock with "
1078 "spinlock or critical section held (%s) %s @ %s:%d",
1079 class->lc_name, lock->lo_name,
1080 fixup_filename(file), line);
1081
1082 /*
1083 * If this is the first lock acquired then just return as
1084 * no order checking is needed.
1085 */
1086 lock_list = td->td_sleeplocks;
1087 if (lock_list == NULL || lock_list->ll_count == 0)
1088 return;
1089 } else {
1090
1091 /*
1092 * If this is the first lock, just return as no order
1093 * checking is needed. Avoid problems with thread
1094 * migration pinning the thread while checking if
1095 * spinlocks are held. If at least one spinlock is held
1096 * the thread is in a safe path and it is allowed to
1097 * unpin it.
1098 */
1099 sched_pin();
1100 lock_list = PCPU_GET(spinlocks);
1101 if (lock_list == NULL || lock_list->ll_count == 0) {
1102 sched_unpin();
1103 return;
1104 }
1105 sched_unpin();
1106 }
1107
1108 /*
1109 * Check to see if we are recursing on a lock we already own. If
1110 * so, make sure that we don't mismatch exclusive and shared lock
1111 * acquires.
1112 */
1113 lock1 = find_instance(lock_list, lock);
1114 if (lock1 != NULL) {
1115 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 &&
1116 (flags & LOP_EXCLUSIVE) == 0) {
1117 printf("shared lock of (%s) %s @ %s:%d\n",
1118 class->lc_name, lock->lo_name,
1119 fixup_filename(file), line);
1120 printf("while exclusively locked from %s:%d\n",
1121 fixup_filename(lock1->li_file), lock1->li_line);
1122 kassert_panic("excl->share");
1123 }
1124 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 &&
1125 (flags & LOP_EXCLUSIVE) != 0) {
1126 printf("exclusive lock of (%s) %s @ %s:%d\n",
1127 class->lc_name, lock->lo_name,
1128 fixup_filename(file), line);
1129 printf("while share locked from %s:%d\n",
1130 fixup_filename(lock1->li_file), lock1->li_line);
1131 kassert_panic("share->excl");
1132 }
1133 return;
1134 }
1135
1136 /* Warn if the interlock is not locked exactly once. */
1137 if (interlock != NULL) {
1138 iclass = LOCK_CLASS(interlock);
1139 lock1 = find_instance(lock_list, interlock);
1140 if (lock1 == NULL)
1141 kassert_panic("interlock (%s) %s not locked @ %s:%d",
1142 iclass->lc_name, interlock->lo_name,
1143 fixup_filename(file), line);
1144 else if ((lock1->li_flags & LI_RECURSEMASK) != 0)
1145 kassert_panic("interlock (%s) %s recursed @ %s:%d",
1146 iclass->lc_name, interlock->lo_name,
1147 fixup_filename(file), line);
1148 }
1149
1150 /*
1151 * Find the previously acquired lock, but ignore interlocks.
1152 */
1153 plock = &lock_list->ll_children[lock_list->ll_count - 1];
1154 if (interlock != NULL && plock->li_lock == interlock) {
1155 if (lock_list->ll_count > 1)
1156 plock =
1157 &lock_list->ll_children[lock_list->ll_count - 2];
1158 else {
1159 lle = lock_list->ll_next;
1160
1161 /*
1162 * The interlock is the only lock we hold, so
1163 * simply return.
1164 */
1165 if (lle == NULL)
1166 return;
1167 plock = &lle->ll_children[lle->ll_count - 1];
1168 }
1169 }
1170
1171 /*
1172 * Try to perform most checks without a lock. If this succeeds we
1173 * can skip acquiring the lock and return success. Otherwise we redo
1174 * the check with the lock held to handle races with concurrent updates.
1175 */
1176 w1 = plock->li_lock->lo_witness;
1177 if (witness_lock_order_check(w1, w))
1178 return;
1179
1180 mtx_lock_spin(&w_mtx);
1181 if (witness_lock_order_check(w1, w)) {
1182 mtx_unlock_spin(&w_mtx);
1183 return;
1184 }
1185 witness_lock_order_add(w1, w);
1186
1187 /*
1188 * Check for duplicate locks of the same type. Note that we only
1189 * have to check for this on the last lock we just acquired. Any
1190 * other cases will be caught as lock order violations.
1191 */
1192 if (w1 == w) {
1193 i = w->w_index;
1194 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) &&
1195 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) {
1196 w_rmatrix[i][i] |= WITNESS_REVERSAL;
1197 w->w_reversed = 1;
1198 mtx_unlock_spin(&w_mtx);
1199 printf(
1200 "acquiring duplicate lock of same type: \"%s\"\n",
1201 w->w_name);
1202 printf(" 1st %s @ %s:%d\n", plock->li_lock->lo_name,
1203 fixup_filename(plock->li_file), plock->li_line);
1204 printf(" 2nd %s @ %s:%d\n", lock->lo_name,
1205 fixup_filename(file), line);
1206 witness_debugger(1);
1207 } else
1208 mtx_unlock_spin(&w_mtx);
1209 return;
1210 }
1211 mtx_assert(&w_mtx, MA_OWNED);
1212
1213 /*
1214 * If we know that the lock we are acquiring comes after
1215 * the lock we most recently acquired in the lock order tree,
1216 * then there is no need for any further checks.
1217 */
1218 if (isitmychild(w1, w))
1219 goto out;
1220
1221 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) {
1222 for (i = lle->ll_count - 1; i >= 0; i--, j++) {
1223
1224 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN);
1225 lock1 = &lle->ll_children[i];
1226
1227 /*
1228 * Ignore the interlock.
1229 */
1230 if (interlock == lock1->li_lock)
1231 continue;
1232
1233 /*
1234 * If this lock doesn't undergo witness checking,
1235 * then skip it.
1236 */
1237 w1 = lock1->li_lock->lo_witness;
1238 if (w1 == NULL) {
1239 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0,
1240 ("lock missing witness structure"));
1241 continue;
1242 }
1243
1244 /*
1245 * If we are locking Giant and this is a sleepable
1246 * lock, then skip it.
1247 */
1248 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 &&
1249 lock == &Giant.lock_object)
1250 continue;
1251
1252 /*
1253 * If we are locking a sleepable lock and this lock
1254 * is Giant, then skip it.
1255 */
1256 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1257 lock1->li_lock == &Giant.lock_object)
1258 continue;
1259
1260 /*
1261 * If we are locking a sleepable lock and this lock
1262 * isn't sleepable, we want to treat it as a lock
1263 * order violation to enfore a general lock order of
1264 * sleepable locks before non-sleepable locks.
1265 */
1266 if (((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1267 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0))
1268 goto reversal;
1269
1270 /*
1271 * If we are locking Giant and this is a non-sleepable
1272 * lock, then treat it as a reversal.
1273 */
1274 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 &&
1275 lock == &Giant.lock_object)
1276 goto reversal;
1277
1278 /*
1279 * Check the lock order hierarchy for a reveresal.
1280 */
1281 if (!isitmydescendant(w, w1))
1282 continue;
1283 reversal:
1284
1285 /*
1286 * We have a lock order violation, check to see if it
1287 * is allowed or has already been yelled about.
1288 */
1289 #ifdef BLESSING
1290
1291 /*
1292 * If the lock order is blessed, just bail. We don't
1293 * look for other lock order violations though, which
1294 * may be a bug.
1295 */
1296 if (blessed(w, w1))
1297 goto out;
1298 #endif
1299
1300 /* Bail if this violation is known */
1301 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL)
1302 goto out;
1303
1304 /* Record this as a violation */
1305 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL;
1306 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL;
1307 w->w_reversed = w1->w_reversed = 1;
1308 witness_increment_graph_generation();
1309 mtx_unlock_spin(&w_mtx);
1310
1311 #ifdef WITNESS_NO_VNODE
1312 /*
1313 * There are known LORs between VNODE locks. They are
1314 * not an indication of a bug. VNODE locks are flagged
1315 * as such (LO_IS_VNODE) and we don't yell if the LOR
1316 * is between 2 VNODE locks.
1317 */
1318 if ((lock->lo_flags & LO_IS_VNODE) != 0 &&
1319 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0)
1320 return;
1321 #endif
1322
1323 /*
1324 * Ok, yell about it.
1325 */
1326 if (((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1327 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0))
1328 printf(
1329 "lock order reversal: (sleepable after non-sleepable)\n");
1330 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0
1331 && lock == &Giant.lock_object)
1332 printf(
1333 "lock order reversal: (Giant after non-sleepable)\n");
1334 else
1335 printf("lock order reversal:\n");
1336
1337 /*
1338 * Try to locate an earlier lock with
1339 * witness w in our list.
1340 */
1341 do {
1342 lock2 = &lle->ll_children[i];
1343 MPASS(lock2->li_lock != NULL);
1344 if (lock2->li_lock->lo_witness == w)
1345 break;
1346 if (i == 0 && lle->ll_next != NULL) {
1347 lle = lle->ll_next;
1348 i = lle->ll_count - 1;
1349 MPASS(i >= 0 && i < LOCK_NCHILDREN);
1350 } else
1351 i--;
1352 } while (i >= 0);
1353 if (i < 0) {
1354 printf(" 1st %p %s (%s) @ %s:%d\n",
1355 lock1->li_lock, lock1->li_lock->lo_name,
1356 w1->w_name, fixup_filename(lock1->li_file),
1357 lock1->li_line);
1358 printf(" 2nd %p %s (%s) @ %s:%d\n", lock,
1359 lock->lo_name, w->w_name,
1360 fixup_filename(file), line);
1361 } else {
1362 printf(" 1st %p %s (%s) @ %s:%d\n",
1363 lock2->li_lock, lock2->li_lock->lo_name,
1364 lock2->li_lock->lo_witness->w_name,
1365 fixup_filename(lock2->li_file),
1366 lock2->li_line);
1367 printf(" 2nd %p %s (%s) @ %s:%d\n",
1368 lock1->li_lock, lock1->li_lock->lo_name,
1369 w1->w_name, fixup_filename(lock1->li_file),
1370 lock1->li_line);
1371 printf(" 3rd %p %s (%s) @ %s:%d\n", lock,
1372 lock->lo_name, w->w_name,
1373 fixup_filename(file), line);
1374 }
1375 witness_debugger(1);
1376 return;
1377 }
1378 }
1379
1380 /*
1381 * If requested, build a new lock order. However, don't build a new
1382 * relationship between a sleepable lock and Giant if it is in the
1383 * wrong direction. The correct lock order is that sleepable locks
1384 * always come before Giant.
1385 */
1386 if (flags & LOP_NEWORDER &&
1387 !(plock->li_lock == &Giant.lock_object &&
1388 (lock->lo_flags & LO_SLEEPABLE) != 0)) {
1389 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
1390 w->w_name, plock->li_lock->lo_witness->w_name);
1391 itismychild(plock->li_lock->lo_witness, w);
1392 }
1393 out:
1394 mtx_unlock_spin(&w_mtx);
1395 }
1396
1397 void
1398 witness_lock(struct lock_object *lock, int flags, const char *file, int line)
1399 {
1400 struct lock_list_entry **lock_list, *lle;
1401 struct lock_instance *instance;
1402 struct witness *w;
1403 struct thread *td;
1404
1405 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL ||
1406 panicstr != NULL)
1407 return;
1408 w = lock->lo_witness;
1409 td = curthread;
1410
1411 /* Determine lock list for this lock. */
1412 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK)
1413 lock_list = &td->td_sleeplocks;
1414 else
1415 lock_list = PCPU_PTR(spinlocks);
1416
1417 /* Check to see if we are recursing on a lock we already own. */
1418 instance = find_instance(*lock_list, lock);
1419 if (instance != NULL) {
1420 instance->li_flags++;
1421 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__,
1422 td->td_proc->p_pid, lock->lo_name,
1423 instance->li_flags & LI_RECURSEMASK);
1424 instance->li_file = file;
1425 instance->li_line = line;
1426 return;
1427 }
1428
1429 /* Update per-witness last file and line acquire. */
1430 w->w_file = file;
1431 w->w_line = line;
1432
1433 /* Find the next open lock instance in the list and fill it. */
1434 lle = *lock_list;
1435 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) {
1436 lle = witness_lock_list_get();
1437 if (lle == NULL)
1438 return;
1439 lle->ll_next = *lock_list;
1440 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__,
1441 td->td_proc->p_pid, lle);
1442 *lock_list = lle;
1443 }
1444 instance = &lle->ll_children[lle->ll_count++];
1445 instance->li_lock = lock;
1446 instance->li_line = line;
1447 instance->li_file = file;
1448 if ((flags & LOP_EXCLUSIVE) != 0)
1449 instance->li_flags = LI_EXCLUSIVE;
1450 else
1451 instance->li_flags = 0;
1452 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__,
1453 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1);
1454 }
1455
1456 void
1457 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line)
1458 {
1459 struct lock_instance *instance;
1460 struct lock_class *class;
1461
1462 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1463 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
1464 return;
1465 class = LOCK_CLASS(lock);
1466 if (witness_watch) {
1467 if ((lock->lo_flags & LO_UPGRADABLE) == 0)
1468 kassert_panic(
1469 "upgrade of non-upgradable lock (%s) %s @ %s:%d",
1470 class->lc_name, lock->lo_name,
1471 fixup_filename(file), line);
1472 if ((class->lc_flags & LC_SLEEPLOCK) == 0)
1473 kassert_panic(
1474 "upgrade of non-sleep lock (%s) %s @ %s:%d",
1475 class->lc_name, lock->lo_name,
1476 fixup_filename(file), line);
1477 }
1478 instance = find_instance(curthread->td_sleeplocks, lock);
1479 if (instance == NULL) {
1480 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d",
1481 class->lc_name, lock->lo_name,
1482 fixup_filename(file), line);
1483 return;
1484 }
1485 if (witness_watch) {
1486 if ((instance->li_flags & LI_EXCLUSIVE) != 0)
1487 kassert_panic(
1488 "upgrade of exclusive lock (%s) %s @ %s:%d",
1489 class->lc_name, lock->lo_name,
1490 fixup_filename(file), line);
1491 if ((instance->li_flags & LI_RECURSEMASK) != 0)
1492 kassert_panic(
1493 "upgrade of recursed lock (%s) %s r=%d @ %s:%d",
1494 class->lc_name, lock->lo_name,
1495 instance->li_flags & LI_RECURSEMASK,
1496 fixup_filename(file), line);
1497 }
1498 instance->li_flags |= LI_EXCLUSIVE;
1499 }
1500
1501 void
1502 witness_downgrade(struct lock_object *lock, int flags, const char *file,
1503 int line)
1504 {
1505 struct lock_instance *instance;
1506 struct lock_class *class;
1507
1508 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1509 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
1510 return;
1511 class = LOCK_CLASS(lock);
1512 if (witness_watch) {
1513 if ((lock->lo_flags & LO_UPGRADABLE) == 0)
1514 kassert_panic(
1515 "downgrade of non-upgradable lock (%s) %s @ %s:%d",
1516 class->lc_name, lock->lo_name,
1517 fixup_filename(file), line);
1518 if ((class->lc_flags & LC_SLEEPLOCK) == 0)
1519 kassert_panic(
1520 "downgrade of non-sleep lock (%s) %s @ %s:%d",
1521 class->lc_name, lock->lo_name,
1522 fixup_filename(file), line);
1523 }
1524 instance = find_instance(curthread->td_sleeplocks, lock);
1525 if (instance == NULL) {
1526 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d",
1527 class->lc_name, lock->lo_name,
1528 fixup_filename(file), line);
1529 return;
1530 }
1531 if (witness_watch) {
1532 if ((instance->li_flags & LI_EXCLUSIVE) == 0)
1533 kassert_panic(
1534 "downgrade of shared lock (%s) %s @ %s:%d",
1535 class->lc_name, lock->lo_name,
1536 fixup_filename(file), line);
1537 if ((instance->li_flags & LI_RECURSEMASK) != 0)
1538 kassert_panic(
1539 "downgrade of recursed lock (%s) %s r=%d @ %s:%d",
1540 class->lc_name, lock->lo_name,
1541 instance->li_flags & LI_RECURSEMASK,
1542 fixup_filename(file), line);
1543 }
1544 instance->li_flags &= ~LI_EXCLUSIVE;
1545 }
1546
1547 void
1548 witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
1549 {
1550 struct lock_list_entry **lock_list, *lle;
1551 struct lock_instance *instance;
1552 struct lock_class *class;
1553 struct thread *td;
1554 register_t s;
1555 int i, j;
1556
1557 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL)
1558 return;
1559 td = curthread;
1560 class = LOCK_CLASS(lock);
1561
1562 /* Find lock instance associated with this lock. */
1563 if (class->lc_flags & LC_SLEEPLOCK)
1564 lock_list = &td->td_sleeplocks;
1565 else
1566 lock_list = PCPU_PTR(spinlocks);
1567 lle = *lock_list;
1568 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next)
1569 for (i = 0; i < (*lock_list)->ll_count; i++) {
1570 instance = &(*lock_list)->ll_children[i];
1571 if (instance->li_lock == lock)
1572 goto found;
1573 }
1574
1575 /*
1576 * When disabling WITNESS through witness_watch we could end up in
1577 * having registered locks in the td_sleeplocks queue.
1578 * We have to make sure we flush these queues, so just search for
1579 * eventual register locks and remove them.
1580 */
1581 if (witness_watch > 0) {
1582 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name,
1583 lock->lo_name, fixup_filename(file), line);
1584 return;
1585 } else {
1586 return;
1587 }
1588 found:
1589
1590 /* First, check for shared/exclusive mismatches. */
1591 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 &&
1592 (flags & LOP_EXCLUSIVE) == 0) {
1593 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name,
1594 lock->lo_name, fixup_filename(file), line);
1595 printf("while exclusively locked from %s:%d\n",
1596 fixup_filename(instance->li_file), instance->li_line);
1597 kassert_panic("excl->ushare");
1598 }
1599 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 &&
1600 (flags & LOP_EXCLUSIVE) != 0) {
1601 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name,
1602 lock->lo_name, fixup_filename(file), line);
1603 printf("while share locked from %s:%d\n",
1604 fixup_filename(instance->li_file),
1605 instance->li_line);
1606 kassert_panic("share->uexcl");
1607 }
1608 /* If we are recursed, unrecurse. */
1609 if ((instance->li_flags & LI_RECURSEMASK) > 0) {
1610 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__,
1611 td->td_proc->p_pid, instance->li_lock->lo_name,
1612 instance->li_flags);
1613 instance->li_flags--;
1614 return;
1615 }
1616 /* The lock is now being dropped, check for NORELEASE flag */
1617 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) {
1618 printf("forbidden unlock of (%s) %s @ %s:%d\n", class->lc_name,
1619 lock->lo_name, fixup_filename(file), line);
1620 kassert_panic("lock marked norelease");
1621 }
1622
1623 /* Otherwise, remove this item from the list. */
1624 s = intr_disable();
1625 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__,
1626 td->td_proc->p_pid, instance->li_lock->lo_name,
1627 (*lock_list)->ll_count - 1);
1628 for (j = i; j < (*lock_list)->ll_count - 1; j++)
1629 (*lock_list)->ll_children[j] =
1630 (*lock_list)->ll_children[j + 1];
1631 (*lock_list)->ll_count--;
1632 intr_restore(s);
1633
1634 /*
1635 * In order to reduce contention on w_mtx, we want to keep always an
1636 * head object into lists so that frequent allocation from the
1637 * free witness pool (and subsequent locking) is avoided.
1638 * In order to maintain the current code simple, when the head
1639 * object is totally unloaded it means also that we do not have
1640 * further objects in the list, so the list ownership needs to be
1641 * hand over to another object if the current head needs to be freed.
1642 */
1643 if ((*lock_list)->ll_count == 0) {
1644 if (*lock_list == lle) {
1645 if (lle->ll_next == NULL)
1646 return;
1647 } else
1648 lle = *lock_list;
1649 *lock_list = lle->ll_next;
1650 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__,
1651 td->td_proc->p_pid, lle);
1652 witness_lock_list_free(lle);
1653 }
1654 }
1655
1656 void
1657 witness_thread_exit(struct thread *td)
1658 {
1659 struct lock_list_entry *lle;
1660 int i, n;
1661
1662 lle = td->td_sleeplocks;
1663 if (lle == NULL || panicstr != NULL)
1664 return;
1665 if (lle->ll_count != 0) {
1666 for (n = 0; lle != NULL; lle = lle->ll_next)
1667 for (i = lle->ll_count - 1; i >= 0; i--) {
1668 if (n == 0)
1669 printf("Thread %p exiting with the following locks held:\n",
1670 td);
1671 n++;
1672 witness_list_lock(&lle->ll_children[i], printf);
1673
1674 }
1675 kassert_panic(
1676 "Thread %p cannot exit while holding sleeplocks\n", td);
1677 }
1678 witness_lock_list_free(lle);
1679 }
1680
1681 /*
1682 * Warn if any locks other than 'lock' are held. Flags can be passed in to
1683 * exempt Giant and sleepable locks from the checks as well. If any
1684 * non-exempt locks are held, then a supplied message is printed to the
1685 * console along with a list of the offending locks. If indicated in the
1686 * flags then a failure results in a panic as well.
1687 */
1688 int
1689 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...)
1690 {
1691 struct lock_list_entry *lock_list, *lle;
1692 struct lock_instance *lock1;
1693 struct thread *td;
1694 va_list ap;
1695 int i, n;
1696
1697 if (witness_cold || witness_watch < 1 || panicstr != NULL)
1698 return (0);
1699 n = 0;
1700 td = curthread;
1701 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next)
1702 for (i = lle->ll_count - 1; i >= 0; i--) {
1703 lock1 = &lle->ll_children[i];
1704 if (lock1->li_lock == lock)
1705 continue;
1706 if (flags & WARN_GIANTOK &&
1707 lock1->li_lock == &Giant.lock_object)
1708 continue;
1709 if (flags & WARN_SLEEPOK &&
1710 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0)
1711 continue;
1712 if (n == 0) {
1713 va_start(ap, fmt);
1714 vprintf(fmt, ap);
1715 va_end(ap);
1716 printf(" with the following");
1717 if (flags & WARN_SLEEPOK)
1718 printf(" non-sleepable");
1719 printf(" locks held:\n");
1720 }
1721 n++;
1722 witness_list_lock(lock1, printf);
1723 }
1724
1725 /*
1726 * Pin the thread in order to avoid problems with thread migration.
1727 * Once that all verifies are passed about spinlocks ownership,
1728 * the thread is in a safe path and it can be unpinned.
1729 */
1730 sched_pin();
1731 lock_list = PCPU_GET(spinlocks);
1732 if (lock_list != NULL && lock_list->ll_count != 0) {
1733 sched_unpin();
1734
1735 /*
1736 * We should only have one spinlock and as long as
1737 * the flags cannot match for this locks class,
1738 * check if the first spinlock is the one curthread
1739 * should hold.
1740 */
1741 lock1 = &lock_list->ll_children[lock_list->ll_count - 1];
1742 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL &&
1743 lock1->li_lock == lock && n == 0)
1744 return (0);
1745
1746 va_start(ap, fmt);
1747 vprintf(fmt, ap);
1748 va_end(ap);
1749 printf(" with the following");
1750 if (flags & WARN_SLEEPOK)
1751 printf(" non-sleepable");
1752 printf(" locks held:\n");
1753 n += witness_list_locks(&lock_list, printf);
1754 } else
1755 sched_unpin();
1756 if (flags & WARN_PANIC && n)
1757 kassert_panic("%s", __func__);
1758 else
1759 witness_debugger(n);
1760 return (n);
1761 }
1762
1763 const char *
1764 witness_file(struct lock_object *lock)
1765 {
1766 struct witness *w;
1767
1768 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
1769 return ("?");
1770 w = lock->lo_witness;
1771 return (w->w_file);
1772 }
1773
1774 int
1775 witness_line(struct lock_object *lock)
1776 {
1777 struct witness *w;
1778
1779 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
1780 return (0);
1781 w = lock->lo_witness;
1782 return (w->w_line);
1783 }
1784
1785 static struct witness *
1786 enroll(const char *description, struct lock_class *lock_class)
1787 {
1788 struct witness *w;
1789 struct witness_list *typelist;
1790
1791 MPASS(description != NULL);
1792
1793 if (witness_watch == -1 || panicstr != NULL)
1794 return (NULL);
1795 if ((lock_class->lc_flags & LC_SPINLOCK)) {
1796 if (witness_skipspin)
1797 return (NULL);
1798 else
1799 typelist = &w_spin;
1800 } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) {
1801 typelist = &w_sleep;
1802 } else {
1803 kassert_panic("lock class %s is not sleep or spin",
1804 lock_class->lc_name);
1805 return (NULL);
1806 }
1807
1808 mtx_lock_spin(&w_mtx);
1809 w = witness_hash_get(description);
1810 if (w)
1811 goto found;
1812 if ((w = witness_get()) == NULL)
1813 return (NULL);
1814 MPASS(strlen(description) < MAX_W_NAME);
1815 strcpy(w->w_name, description);
1816 w->w_class = lock_class;
1817 w->w_refcount = 1;
1818 STAILQ_INSERT_HEAD(&w_all, w, w_list);
1819 if (lock_class->lc_flags & LC_SPINLOCK) {
1820 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist);
1821 w_spin_cnt++;
1822 } else if (lock_class->lc_flags & LC_SLEEPLOCK) {
1823 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist);
1824 w_sleep_cnt++;
1825 }
1826
1827 /* Insert new witness into the hash */
1828 witness_hash_put(w);
1829 witness_increment_graph_generation();
1830 mtx_unlock_spin(&w_mtx);
1831 return (w);
1832 found:
1833 w->w_refcount++;
1834 mtx_unlock_spin(&w_mtx);
1835 if (lock_class != w->w_class)
1836 kassert_panic(
1837 "lock (%s) %s does not match earlier (%s) lock",
1838 description, lock_class->lc_name,
1839 w->w_class->lc_name);
1840 return (w);
1841 }
1842
1843 static void
1844 depart(struct witness *w)
1845 {
1846 struct witness_list *list;
1847
1848 MPASS(w->w_refcount == 0);
1849 if (w->w_class->lc_flags & LC_SLEEPLOCK) {
1850 list = &w_sleep;
1851 w_sleep_cnt--;
1852 } else {
1853 list = &w_spin;
1854 w_spin_cnt--;
1855 }
1856 /*
1857 * Set file to NULL as it may point into a loadable module.
1858 */
1859 w->w_file = NULL;
1860 w->w_line = 0;
1861 witness_increment_graph_generation();
1862 }
1863
1864
1865 static void
1866 adopt(struct witness *parent, struct witness *child)
1867 {
1868 int pi, ci, i, j;
1869
1870 if (witness_cold == 0)
1871 mtx_assert(&w_mtx, MA_OWNED);
1872
1873 /* If the relationship is already known, there's no work to be done. */
1874 if (isitmychild(parent, child))
1875 return;
1876
1877 /* When the structure of the graph changes, bump up the generation. */
1878 witness_increment_graph_generation();
1879
1880 /*
1881 * The hard part ... create the direct relationship, then propagate all
1882 * indirect relationships.
1883 */
1884 pi = parent->w_index;
1885 ci = child->w_index;
1886 WITNESS_INDEX_ASSERT(pi);
1887 WITNESS_INDEX_ASSERT(ci);
1888 MPASS(pi != ci);
1889 w_rmatrix[pi][ci] |= WITNESS_PARENT;
1890 w_rmatrix[ci][pi] |= WITNESS_CHILD;
1891
1892 /*
1893 * If parent was not already an ancestor of child,
1894 * then we increment the descendant and ancestor counters.
1895 */
1896 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) {
1897 parent->w_num_descendants++;
1898 child->w_num_ancestors++;
1899 }
1900
1901 /*
1902 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as
1903 * an ancestor of 'pi' during this loop.
1904 */
1905 for (i = 1; i <= w_max_used_index; i++) {
1906 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 &&
1907 (i != pi))
1908 continue;
1909
1910 /* Find each descendant of 'i' and mark it as a descendant. */
1911 for (j = 1; j <= w_max_used_index; j++) {
1912
1913 /*
1914 * Skip children that are already marked as
1915 * descendants of 'i'.
1916 */
1917 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK)
1918 continue;
1919
1920 /*
1921 * We are only interested in descendants of 'ci'. Note
1922 * that 'ci' itself is counted as a descendant of 'ci'.
1923 */
1924 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 &&
1925 (j != ci))
1926 continue;
1927 w_rmatrix[i][j] |= WITNESS_ANCESTOR;
1928 w_rmatrix[j][i] |= WITNESS_DESCENDANT;
1929 w_data[i].w_num_descendants++;
1930 w_data[j].w_num_ancestors++;
1931
1932 /*
1933 * Make sure we aren't marking a node as both an
1934 * ancestor and descendant. We should have caught
1935 * this as a lock order reversal earlier.
1936 */
1937 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) &&
1938 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) {
1939 printf("witness rmatrix paradox! [%d][%d]=%d "
1940 "both ancestor and descendant\n",
1941 i, j, w_rmatrix[i][j]);
1942 kdb_backtrace();
1943 printf("Witness disabled.\n");
1944 witness_watch = -1;
1945 }
1946 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) &&
1947 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) {
1948 printf("witness rmatrix paradox! [%d][%d]=%d "
1949 "both ancestor and descendant\n",
1950 j, i, w_rmatrix[j][i]);
1951 kdb_backtrace();
1952 printf("Witness disabled.\n");
1953 witness_watch = -1;
1954 }
1955 }
1956 }
1957 }
1958
1959 static void
1960 itismychild(struct witness *parent, struct witness *child)
1961 {
1962 int unlocked;
1963
1964 MPASS(child != NULL && parent != NULL);
1965 if (witness_cold == 0)
1966 mtx_assert(&w_mtx, MA_OWNED);
1967
1968 if (!witness_lock_type_equal(parent, child)) {
1969 if (witness_cold == 0) {
1970 unlocked = 1;
1971 mtx_unlock_spin(&w_mtx);
1972 } else {
1973 unlocked = 0;
1974 }
1975 kassert_panic(
1976 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not "
1977 "the same lock type", __func__, parent->w_name,
1978 parent->w_class->lc_name, child->w_name,
1979 child->w_class->lc_name);
1980 if (unlocked)
1981 mtx_lock_spin(&w_mtx);
1982 }
1983 adopt(parent, child);
1984 }
1985
1986 /*
1987 * Generic code for the isitmy*() functions. The rmask parameter is the
1988 * expected relationship of w1 to w2.
1989 */
1990 static int
1991 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname)
1992 {
1993 unsigned char r1, r2;
1994 int i1, i2;
1995
1996 i1 = w1->w_index;
1997 i2 = w2->w_index;
1998 WITNESS_INDEX_ASSERT(i1);
1999 WITNESS_INDEX_ASSERT(i2);
2000 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK;
2001 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK;
2002
2003 /* The flags on one better be the inverse of the flags on the other */
2004 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) ||
2005 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) {
2006 /* Don't squawk if we're potentially racing with an update. */
2007 if (!mtx_owned(&w_mtx))
2008 return (0);
2009 printf("%s: rmatrix mismatch between %s (index %d) and %s "
2010 "(index %d): w_rmatrix[%d][%d] == %hhx but "
2011 "w_rmatrix[%d][%d] == %hhx\n",
2012 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1,
2013 i2, i1, r2);
2014 kdb_backtrace();
2015 printf("Witness disabled.\n");
2016 witness_watch = -1;
2017 }
2018 return (r1 & rmask);
2019 }
2020
2021 /*
2022 * Checks if @child is a direct child of @parent.
2023 */
2024 static int
2025 isitmychild(struct witness *parent, struct witness *child)
2026 {
2027
2028 return (_isitmyx(parent, child, WITNESS_PARENT, __func__));
2029 }
2030
2031 /*
2032 * Checks if @descendant is a direct or inderect descendant of @ancestor.
2033 */
2034 static int
2035 isitmydescendant(struct witness *ancestor, struct witness *descendant)
2036 {
2037
2038 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK,
2039 __func__));
2040 }
2041
2042 #ifdef BLESSING
2043 static int
2044 blessed(struct witness *w1, struct witness *w2)
2045 {
2046 int i;
2047 struct witness_blessed *b;
2048
2049 for (i = 0; i < blessed_count; i++) {
2050 b = &blessed_list[i];
2051 if (strcmp(w1->w_name, b->b_lock1) == 0) {
2052 if (strcmp(w2->w_name, b->b_lock2) == 0)
2053 return (1);
2054 continue;
2055 }
2056 if (strcmp(w1->w_name, b->b_lock2) == 0)
2057 if (strcmp(w2->w_name, b->b_lock1) == 0)
2058 return (1);
2059 }
2060 return (0);
2061 }
2062 #endif
2063
2064 static struct witness *
2065 witness_get(void)
2066 {
2067 struct witness *w;
2068 int index;
2069
2070 if (witness_cold == 0)
2071 mtx_assert(&w_mtx, MA_OWNED);
2072
2073 if (witness_watch == -1) {
2074 mtx_unlock_spin(&w_mtx);
2075 return (NULL);
2076 }
2077 if (STAILQ_EMPTY(&w_free)) {
2078 witness_watch = -1;
2079 mtx_unlock_spin(&w_mtx);
2080 printf("WITNESS: unable to allocate a new witness object\n");
2081 return (NULL);
2082 }
2083 w = STAILQ_FIRST(&w_free);
2084 STAILQ_REMOVE_HEAD(&w_free, w_list);
2085 w_free_cnt--;
2086 index = w->w_index;
2087 MPASS(index > 0 && index == w_max_used_index+1 &&
2088 index < WITNESS_COUNT);
2089 bzero(w, sizeof(*w));
2090 w->w_index = index;
2091 if (index > w_max_used_index)
2092 w_max_used_index = index;
2093 return (w);
2094 }
2095
2096 static void
2097 witness_free(struct witness *w)
2098 {
2099
2100 STAILQ_INSERT_HEAD(&w_free, w, w_list);
2101 w_free_cnt++;
2102 }
2103
2104 static struct lock_list_entry *
2105 witness_lock_list_get(void)
2106 {
2107 struct lock_list_entry *lle;
2108
2109 if (witness_watch == -1)
2110 return (NULL);
2111 mtx_lock_spin(&w_mtx);
2112 lle = w_lock_list_free;
2113 if (lle == NULL) {
2114 witness_watch = -1;
2115 mtx_unlock_spin(&w_mtx);
2116 printf("%s: witness exhausted\n", __func__);
2117 return (NULL);
2118 }
2119 w_lock_list_free = lle->ll_next;
2120 mtx_unlock_spin(&w_mtx);
2121 bzero(lle, sizeof(*lle));
2122 return (lle);
2123 }
2124
2125 static void
2126 witness_lock_list_free(struct lock_list_entry *lle)
2127 {
2128
2129 mtx_lock_spin(&w_mtx);
2130 lle->ll_next = w_lock_list_free;
2131 w_lock_list_free = lle;
2132 mtx_unlock_spin(&w_mtx);
2133 }
2134
2135 static struct lock_instance *
2136 find_instance(struct lock_list_entry *list, const struct lock_object *lock)
2137 {
2138 struct lock_list_entry *lle;
2139 struct lock_instance *instance;
2140 int i;
2141
2142 for (lle = list; lle != NULL; lle = lle->ll_next)
2143 for (i = lle->ll_count - 1; i >= 0; i--) {
2144 instance = &lle->ll_children[i];
2145 if (instance->li_lock == lock)
2146 return (instance);
2147 }
2148 return (NULL);
2149 }
2150
2151 static void
2152 witness_list_lock(struct lock_instance *instance,
2153 int (*prnt)(const char *fmt, ...))
2154 {
2155 struct lock_object *lock;
2156
2157 lock = instance->li_lock;
2158 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ?
2159 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name);
2160 if (lock->lo_witness->w_name != lock->lo_name)
2161 prnt(" (%s)", lock->lo_witness->w_name);
2162 prnt(" r = %d (%p) locked @ %s:%d\n",
2163 instance->li_flags & LI_RECURSEMASK, lock,
2164 fixup_filename(instance->li_file), instance->li_line);
2165 }
2166
2167 #ifdef DDB
2168 static int
2169 witness_thread_has_locks(struct thread *td)
2170 {
2171
2172 if (td->td_sleeplocks == NULL)
2173 return (0);
2174 return (td->td_sleeplocks->ll_count != 0);
2175 }
2176
2177 static int
2178 witness_proc_has_locks(struct proc *p)
2179 {
2180 struct thread *td;
2181
2182 FOREACH_THREAD_IN_PROC(p, td) {
2183 if (witness_thread_has_locks(td))
2184 return (1);
2185 }
2186 return (0);
2187 }
2188 #endif
2189
2190 int
2191 witness_list_locks(struct lock_list_entry **lock_list,
2192 int (*prnt)(const char *fmt, ...))
2193 {
2194 struct lock_list_entry *lle;
2195 int i, nheld;
2196
2197 nheld = 0;
2198 for (lle = *lock_list; lle != NULL; lle = lle->ll_next)
2199 for (i = lle->ll_count - 1; i >= 0; i--) {
2200 witness_list_lock(&lle->ll_children[i], prnt);
2201 nheld++;
2202 }
2203 return (nheld);
2204 }
2205
2206 /*
2207 * This is a bit risky at best. We call this function when we have timed
2208 * out acquiring a spin lock, and we assume that the other CPU is stuck
2209 * with this lock held. So, we go groveling around in the other CPU's
2210 * per-cpu data to try to find the lock instance for this spin lock to
2211 * see when it was last acquired.
2212 */
2213 void
2214 witness_display_spinlock(struct lock_object *lock, struct thread *owner,
2215 int (*prnt)(const char *fmt, ...))
2216 {
2217 struct lock_instance *instance;
2218 struct pcpu *pc;
2219
2220 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU)
2221 return;
2222 pc = pcpu_find(owner->td_oncpu);
2223 instance = find_instance(pc->pc_spinlocks, lock);
2224 if (instance != NULL)
2225 witness_list_lock(instance, prnt);
2226 }
2227
2228 void
2229 witness_save(struct lock_object *lock, const char **filep, int *linep)
2230 {
2231 struct lock_list_entry *lock_list;
2232 struct lock_instance *instance;
2233 struct lock_class *class;
2234
2235 /*
2236 * This function is used independently in locking code to deal with
2237 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant
2238 * is gone.
2239 */
2240 if (SCHEDULER_STOPPED())
2241 return;
2242 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2243 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2244 return;
2245 class = LOCK_CLASS(lock);
2246 if (class->lc_flags & LC_SLEEPLOCK)
2247 lock_list = curthread->td_sleeplocks;
2248 else {
2249 if (witness_skipspin)
2250 return;
2251 lock_list = PCPU_GET(spinlocks);
2252 }
2253 instance = find_instance(lock_list, lock);
2254 if (instance == NULL) {
2255 kassert_panic("%s: lock (%s) %s not locked", __func__,
2256 class->lc_name, lock->lo_name);
2257 return;
2258 }
2259 *filep = instance->li_file;
2260 *linep = instance->li_line;
2261 }
2262
2263 void
2264 witness_restore(struct lock_object *lock, const char *file, int line)
2265 {
2266 struct lock_list_entry *lock_list;
2267 struct lock_instance *instance;
2268 struct lock_class *class;
2269
2270 /*
2271 * This function is used independently in locking code to deal with
2272 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant
2273 * is gone.
2274 */
2275 if (SCHEDULER_STOPPED())
2276 return;
2277 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2278 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2279 return;
2280 class = LOCK_CLASS(lock);
2281 if (class->lc_flags & LC_SLEEPLOCK)
2282 lock_list = curthread->td_sleeplocks;
2283 else {
2284 if (witness_skipspin)
2285 return;
2286 lock_list = PCPU_GET(spinlocks);
2287 }
2288 instance = find_instance(lock_list, lock);
2289 if (instance == NULL)
2290 kassert_panic("%s: lock (%s) %s not locked", __func__,
2291 class->lc_name, lock->lo_name);
2292 lock->lo_witness->w_file = file;
2293 lock->lo_witness->w_line = line;
2294 if (instance == NULL)
2295 return;
2296 instance->li_file = file;
2297 instance->li_line = line;
2298 }
2299
2300 void
2301 witness_assert(const struct lock_object *lock, int flags, const char *file,
2302 int line)
2303 {
2304 #ifdef INVARIANT_SUPPORT
2305 struct lock_instance *instance;
2306 struct lock_class *class;
2307
2308 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL)
2309 return;
2310 class = LOCK_CLASS(lock);
2311 if ((class->lc_flags & LC_SLEEPLOCK) != 0)
2312 instance = find_instance(curthread->td_sleeplocks, lock);
2313 else if ((class->lc_flags & LC_SPINLOCK) != 0)
2314 instance = find_instance(PCPU_GET(spinlocks), lock);
2315 else {
2316 kassert_panic("Lock (%s) %s is not sleep or spin!",
2317 class->lc_name, lock->lo_name);
2318 return;
2319 }
2320 switch (flags) {
2321 case LA_UNLOCKED:
2322 if (instance != NULL)
2323 kassert_panic("Lock (%s) %s locked @ %s:%d.",
2324 class->lc_name, lock->lo_name,
2325 fixup_filename(file), line);
2326 break;
2327 case LA_LOCKED:
2328 case LA_LOCKED | LA_RECURSED:
2329 case LA_LOCKED | LA_NOTRECURSED:
2330 case LA_SLOCKED:
2331 case LA_SLOCKED | LA_RECURSED:
2332 case LA_SLOCKED | LA_NOTRECURSED:
2333 case LA_XLOCKED:
2334 case LA_XLOCKED | LA_RECURSED:
2335 case LA_XLOCKED | LA_NOTRECURSED:
2336 if (instance == NULL) {
2337 kassert_panic("Lock (%s) %s not locked @ %s:%d.",
2338 class->lc_name, lock->lo_name,
2339 fixup_filename(file), line);
2340 break;
2341 }
2342 if ((flags & LA_XLOCKED) != 0 &&
2343 (instance->li_flags & LI_EXCLUSIVE) == 0)
2344 kassert_panic(
2345 "Lock (%s) %s not exclusively locked @ %s:%d.",
2346 class->lc_name, lock->lo_name,
2347 fixup_filename(file), line);
2348 if ((flags & LA_SLOCKED) != 0 &&
2349 (instance->li_flags & LI_EXCLUSIVE) != 0)
2350 kassert_panic(
2351 "Lock (%s) %s exclusively locked @ %s:%d.",
2352 class->lc_name, lock->lo_name,
2353 fixup_filename(file), line);
2354 if ((flags & LA_RECURSED) != 0 &&
2355 (instance->li_flags & LI_RECURSEMASK) == 0)
2356 kassert_panic("Lock (%s) %s not recursed @ %s:%d.",
2357 class->lc_name, lock->lo_name,
2358 fixup_filename(file), line);
2359 if ((flags & LA_NOTRECURSED) != 0 &&
2360 (instance->li_flags & LI_RECURSEMASK) != 0)
2361 kassert_panic("Lock (%s) %s recursed @ %s:%d.",
2362 class->lc_name, lock->lo_name,
2363 fixup_filename(file), line);
2364 break;
2365 default:
2366 kassert_panic("Invalid lock assertion at %s:%d.",
2367 fixup_filename(file), line);
2368
2369 }
2370 #endif /* INVARIANT_SUPPORT */
2371 }
2372
2373 static void
2374 witness_setflag(struct lock_object *lock, int flag, int set)
2375 {
2376 struct lock_list_entry *lock_list;
2377 struct lock_instance *instance;
2378 struct lock_class *class;
2379
2380 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2381 return;
2382 class = LOCK_CLASS(lock);
2383 if (class->lc_flags & LC_SLEEPLOCK)
2384 lock_list = curthread->td_sleeplocks;
2385 else {
2386 if (witness_skipspin)
2387 return;
2388 lock_list = PCPU_GET(spinlocks);
2389 }
2390 instance = find_instance(lock_list, lock);
2391 if (instance == NULL) {
2392 kassert_panic("%s: lock (%s) %s not locked", __func__,
2393 class->lc_name, lock->lo_name);
2394 return;
2395 }
2396
2397 if (set)
2398 instance->li_flags |= flag;
2399 else
2400 instance->li_flags &= ~flag;
2401 }
2402
2403 void
2404 witness_norelease(struct lock_object *lock)
2405 {
2406
2407 witness_setflag(lock, LI_NORELEASE, 1);
2408 }
2409
2410 void
2411 witness_releaseok(struct lock_object *lock)
2412 {
2413
2414 witness_setflag(lock, LI_NORELEASE, 0);
2415 }
2416
2417 #ifdef DDB
2418 static void
2419 witness_ddb_list(struct thread *td)
2420 {
2421
2422 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2423 KASSERT(kdb_active, ("%s: not in the debugger", __func__));
2424
2425 if (witness_watch < 1)
2426 return;
2427
2428 witness_list_locks(&td->td_sleeplocks, db_printf);
2429
2430 /*
2431 * We only handle spinlocks if td == curthread. This is somewhat broken
2432 * if td is currently executing on some other CPU and holds spin locks
2433 * as we won't display those locks. If we had a MI way of getting
2434 * the per-cpu data for a given cpu then we could use
2435 * td->td_oncpu to get the list of spinlocks for this thread
2436 * and "fix" this.
2437 *
2438 * That still wouldn't really fix this unless we locked the scheduler
2439 * lock or stopped the other CPU to make sure it wasn't changing the
2440 * list out from under us. It is probably best to just not try to
2441 * handle threads on other CPU's for now.
2442 */
2443 if (td == curthread && PCPU_GET(spinlocks) != NULL)
2444 witness_list_locks(PCPU_PTR(spinlocks), db_printf);
2445 }
2446
2447 DB_SHOW_COMMAND(locks, db_witness_list)
2448 {
2449 struct thread *td;
2450
2451 if (have_addr)
2452 td = db_lookup_thread(addr, TRUE);
2453 else
2454 td = kdb_thread;
2455 witness_ddb_list(td);
2456 }
2457
2458 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all)
2459 {
2460 struct thread *td;
2461 struct proc *p;
2462
2463 /*
2464 * It would be nice to list only threads and processes that actually
2465 * held sleep locks, but that information is currently not exported
2466 * by WITNESS.
2467 */
2468 FOREACH_PROC_IN_SYSTEM(p) {
2469 if (!witness_proc_has_locks(p))
2470 continue;
2471 FOREACH_THREAD_IN_PROC(p, td) {
2472 if (!witness_thread_has_locks(td))
2473 continue;
2474 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid,
2475 p->p_comm, td, td->td_tid);
2476 witness_ddb_list(td);
2477 if (db_pager_quit)
2478 return;
2479 }
2480 }
2481 }
2482 DB_SHOW_ALIAS(alllocks, db_witness_list_all)
2483
2484 DB_SHOW_COMMAND(witness, db_witness_display)
2485 {
2486
2487 witness_ddb_display(db_printf);
2488 }
2489 #endif
2490
2491 static int
2492 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS)
2493 {
2494 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2;
2495 struct witness *tmp_w1, *tmp_w2, *w1, *w2;
2496 struct sbuf *sb;
2497 u_int w_rmatrix1, w_rmatrix2;
2498 int error, generation, i, j;
2499
2500 tmp_data1 = NULL;
2501 tmp_data2 = NULL;
2502 tmp_w1 = NULL;
2503 tmp_w2 = NULL;
2504 if (witness_watch < 1) {
2505 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
2506 return (error);
2507 }
2508 if (witness_cold) {
2509 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
2510 return (error);
2511 }
2512 error = 0;
2513 sb = sbuf_new(NULL, NULL, BADSTACK_SBUF_SIZE, SBUF_AUTOEXTEND);
2514 if (sb == NULL)
2515 return (ENOMEM);
2516
2517 /* Allocate and init temporary storage space. */
2518 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
2519 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
2520 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP,
2521 M_WAITOK | M_ZERO);
2522 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP,
2523 M_WAITOK | M_ZERO);
2524 stack_zero(&tmp_data1->wlod_stack);
2525 stack_zero(&tmp_data2->wlod_stack);
2526
2527 restart:
2528 mtx_lock_spin(&w_mtx);
2529 generation = w_generation;
2530 mtx_unlock_spin(&w_mtx);
2531 sbuf_printf(sb, "Number of known direct relationships is %d\n",
2532 w_lohash.wloh_count);
2533 for (i = 1; i < w_max_used_index; i++) {
2534 mtx_lock_spin(&w_mtx);
2535 if (generation != w_generation) {
2536 mtx_unlock_spin(&w_mtx);
2537
2538 /* The graph has changed, try again. */
2539 req->oldidx = 0;
2540 sbuf_clear(sb);
2541 goto restart;
2542 }
2543
2544 w1 = &w_data[i];
2545 if (w1->w_reversed == 0) {
2546 mtx_unlock_spin(&w_mtx);
2547 continue;
2548 }
2549
2550 /* Copy w1 locally so we can release the spin lock. */
2551 *tmp_w1 = *w1;
2552 mtx_unlock_spin(&w_mtx);
2553
2554 if (tmp_w1->w_reversed == 0)
2555 continue;
2556 for (j = 1; j < w_max_used_index; j++) {
2557 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j)
2558 continue;
2559
2560 mtx_lock_spin(&w_mtx);
2561 if (generation != w_generation) {
2562 mtx_unlock_spin(&w_mtx);
2563
2564 /* The graph has changed, try again. */
2565 req->oldidx = 0;
2566 sbuf_clear(sb);
2567 goto restart;
2568 }
2569
2570 w2 = &w_data[j];
2571 data1 = witness_lock_order_get(w1, w2);
2572 data2 = witness_lock_order_get(w2, w1);
2573
2574 /*
2575 * Copy information locally so we can release the
2576 * spin lock.
2577 */
2578 *tmp_w2 = *w2;
2579 w_rmatrix1 = (unsigned int)w_rmatrix[i][j];
2580 w_rmatrix2 = (unsigned int)w_rmatrix[j][i];
2581
2582 if (data1) {
2583 stack_zero(&tmp_data1->wlod_stack);
2584 stack_copy(&data1->wlod_stack,
2585 &tmp_data1->wlod_stack);
2586 }
2587 if (data2 && data2 != data1) {
2588 stack_zero(&tmp_data2->wlod_stack);
2589 stack_copy(&data2->wlod_stack,
2590 &tmp_data2->wlod_stack);
2591 }
2592 mtx_unlock_spin(&w_mtx);
2593
2594 sbuf_printf(sb,
2595 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n",
2596 tmp_w1->w_name, tmp_w1->w_class->lc_name,
2597 tmp_w2->w_name, tmp_w2->w_class->lc_name);
2598 #if 0
2599 sbuf_printf(sb,
2600 "w_rmatrix[%s][%s] == %x, w_rmatrix[%s][%s] == %x\n",
2601 tmp_w1->name, tmp_w2->w_name, w_rmatrix1,
2602 tmp_w2->name, tmp_w1->w_name, w_rmatrix2);
2603 #endif
2604 if (data1) {
2605 sbuf_printf(sb,
2606 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
2607 tmp_w1->w_name, tmp_w1->w_class->lc_name,
2608 tmp_w2->w_name, tmp_w2->w_class->lc_name);
2609 stack_sbuf_print(sb, &tmp_data1->wlod_stack);
2610 sbuf_printf(sb, "\n");
2611 }
2612 if (data2 && data2 != data1) {
2613 sbuf_printf(sb,
2614 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
2615 tmp_w2->w_name, tmp_w2->w_class->lc_name,
2616 tmp_w1->w_name, tmp_w1->w_class->lc_name);
2617 stack_sbuf_print(sb, &tmp_data2->wlod_stack);
2618 sbuf_printf(sb, "\n");
2619 }
2620 }
2621 }
2622 mtx_lock_spin(&w_mtx);
2623 if (generation != w_generation) {
2624 mtx_unlock_spin(&w_mtx);
2625
2626 /*
2627 * The graph changed while we were printing stack data,
2628 * try again.
2629 */
2630 req->oldidx = 0;
2631 sbuf_clear(sb);
2632 goto restart;
2633 }
2634 mtx_unlock_spin(&w_mtx);
2635
2636 /* Free temporary storage space. */
2637 free(tmp_data1, M_TEMP);
2638 free(tmp_data2, M_TEMP);
2639 free(tmp_w1, M_TEMP);
2640 free(tmp_w2, M_TEMP);
2641
2642 sbuf_finish(sb);
2643 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
2644 sbuf_delete(sb);
2645
2646 return (error);
2647 }
2648
2649 static int
2650 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS)
2651 {
2652 struct witness *w;
2653 struct sbuf *sb;
2654 int error;
2655
2656 if (witness_watch < 1) {
2657 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
2658 return (error);
2659 }
2660 if (witness_cold) {
2661 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
2662 return (error);
2663 }
2664 error = 0;
2665
2666 error = sysctl_wire_old_buffer(req, 0);
2667 if (error != 0)
2668 return (error);
2669 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req);
2670 if (sb == NULL)
2671 return (ENOMEM);
2672 sbuf_printf(sb, "\n");
2673
2674 mtx_lock_spin(&w_mtx);
2675 STAILQ_FOREACH(w, &w_all, w_list)
2676 w->w_displayed = 0;
2677 STAILQ_FOREACH(w, &w_all, w_list)
2678 witness_add_fullgraph(sb, w);
2679 mtx_unlock_spin(&w_mtx);
2680
2681 /*
2682 * Close the sbuf and return to userland.
2683 */
2684 error = sbuf_finish(sb);
2685 sbuf_delete(sb);
2686
2687 return (error);
2688 }
2689
2690 static int
2691 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS)
2692 {
2693 int error, value;
2694
2695 value = witness_watch;
2696 error = sysctl_handle_int(oidp, &value, 0, req);
2697 if (error != 0 || req->newptr == NULL)
2698 return (error);
2699 if (value > 1 || value < -1 ||
2700 (witness_watch == -1 && value != witness_watch))
2701 return (EINVAL);
2702 witness_watch = value;
2703 return (0);
2704 }
2705
2706 static void
2707 witness_add_fullgraph(struct sbuf *sb, struct witness *w)
2708 {
2709 int i;
2710
2711 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0))
2712 return;
2713 w->w_displayed = 1;
2714
2715 WITNESS_INDEX_ASSERT(w->w_index);
2716 for (i = 1; i <= w_max_used_index; i++) {
2717 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) {
2718 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name,
2719 w_data[i].w_name);
2720 witness_add_fullgraph(sb, &w_data[i]);
2721 }
2722 }
2723 }
2724
2725 /*
2726 * A simple hash function. Takes a key pointer and a key size. If size == 0,
2727 * interprets the key as a string and reads until the null
2728 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit
2729 * hash value computed from the key.
2730 */
2731 static uint32_t
2732 witness_hash_djb2(const uint8_t *key, uint32_t size)
2733 {
2734 unsigned int hash = 5381;
2735 int i;
2736
2737 /* hash = hash * 33 + key[i] */
2738 if (size)
2739 for (i = 0; i < size; i++)
2740 hash = ((hash << 5) + hash) + (unsigned int)key[i];
2741 else
2742 for (i = 0; key[i] != 0; i++)
2743 hash = ((hash << 5) + hash) + (unsigned int)key[i];
2744
2745 return (hash);
2746 }
2747
2748
2749 /*
2750 * Initializes the two witness hash tables. Called exactly once from
2751 * witness_initialize().
2752 */
2753 static void
2754 witness_init_hash_tables(void)
2755 {
2756 int i;
2757
2758 MPASS(witness_cold);
2759
2760 /* Initialize the hash tables. */
2761 for (i = 0; i < WITNESS_HASH_SIZE; i++)
2762 w_hash.wh_array[i] = NULL;
2763
2764 w_hash.wh_size = WITNESS_HASH_SIZE;
2765 w_hash.wh_count = 0;
2766
2767 /* Initialize the lock order data hash. */
2768 w_lofree = NULL;
2769 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) {
2770 memset(&w_lodata[i], 0, sizeof(w_lodata[i]));
2771 w_lodata[i].wlod_next = w_lofree;
2772 w_lofree = &w_lodata[i];
2773 }
2774 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE;
2775 w_lohash.wloh_count = 0;
2776 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++)
2777 w_lohash.wloh_array[i] = NULL;
2778 }
2779
2780 static struct witness *
2781 witness_hash_get(const char *key)
2782 {
2783 struct witness *w;
2784 uint32_t hash;
2785
2786 MPASS(key != NULL);
2787 if (witness_cold == 0)
2788 mtx_assert(&w_mtx, MA_OWNED);
2789 hash = witness_hash_djb2(key, 0) % w_hash.wh_size;
2790 w = w_hash.wh_array[hash];
2791 while (w != NULL) {
2792 if (strcmp(w->w_name, key) == 0)
2793 goto out;
2794 w = w->w_hash_next;
2795 }
2796
2797 out:
2798 return (w);
2799 }
2800
2801 static void
2802 witness_hash_put(struct witness *w)
2803 {
2804 uint32_t hash;
2805
2806 MPASS(w != NULL);
2807 MPASS(w->w_name != NULL);
2808 if (witness_cold == 0)
2809 mtx_assert(&w_mtx, MA_OWNED);
2810 KASSERT(witness_hash_get(w->w_name) == NULL,
2811 ("%s: trying to add a hash entry that already exists!", __func__));
2812 KASSERT(w->w_hash_next == NULL,
2813 ("%s: w->w_hash_next != NULL", __func__));
2814
2815 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size;
2816 w->w_hash_next = w_hash.wh_array[hash];
2817 w_hash.wh_array[hash] = w;
2818 w_hash.wh_count++;
2819 }
2820
2821
2822 static struct witness_lock_order_data *
2823 witness_lock_order_get(struct witness *parent, struct witness *child)
2824 {
2825 struct witness_lock_order_data *data = NULL;
2826 struct witness_lock_order_key key;
2827 unsigned int hash;
2828
2829 MPASS(parent != NULL && child != NULL);
2830 key.from = parent->w_index;
2831 key.to = child->w_index;
2832 WITNESS_INDEX_ASSERT(key.from);
2833 WITNESS_INDEX_ASSERT(key.to);
2834 if ((w_rmatrix[parent->w_index][child->w_index]
2835 & WITNESS_LOCK_ORDER_KNOWN) == 0)
2836 goto out;
2837
2838 hash = witness_hash_djb2((const char*)&key,
2839 sizeof(key)) % w_lohash.wloh_size;
2840 data = w_lohash.wloh_array[hash];
2841 while (data != NULL) {
2842 if (witness_lock_order_key_equal(&data->wlod_key, &key))
2843 break;
2844 data = data->wlod_next;
2845 }
2846
2847 out:
2848 return (data);
2849 }
2850
2851 /*
2852 * Verify that parent and child have a known relationship, are not the same,
2853 * and child is actually a child of parent. This is done without w_mtx
2854 * to avoid contention in the common case.
2855 */
2856 static int
2857 witness_lock_order_check(struct witness *parent, struct witness *child)
2858 {
2859
2860 if (parent != child &&
2861 w_rmatrix[parent->w_index][child->w_index]
2862 & WITNESS_LOCK_ORDER_KNOWN &&
2863 isitmychild(parent, child))
2864 return (1);
2865
2866 return (0);
2867 }
2868
2869 static int
2870 witness_lock_order_add(struct witness *parent, struct witness *child)
2871 {
2872 struct witness_lock_order_data *data = NULL;
2873 struct witness_lock_order_key key;
2874 unsigned int hash;
2875
2876 MPASS(parent != NULL && child != NULL);
2877 key.from = parent->w_index;
2878 key.to = child->w_index;
2879 WITNESS_INDEX_ASSERT(key.from);
2880 WITNESS_INDEX_ASSERT(key.to);
2881 if (w_rmatrix[parent->w_index][child->w_index]
2882 & WITNESS_LOCK_ORDER_KNOWN)
2883 return (1);
2884
2885 hash = witness_hash_djb2((const char*)&key,
2886 sizeof(key)) % w_lohash.wloh_size;
2887 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN;
2888 data = w_lofree;
2889 if (data == NULL)
2890 return (0);
2891 w_lofree = data->wlod_next;
2892 data->wlod_next = w_lohash.wloh_array[hash];
2893 data->wlod_key = key;
2894 w_lohash.wloh_array[hash] = data;
2895 w_lohash.wloh_count++;
2896 stack_zero(&data->wlod_stack);
2897 stack_save(&data->wlod_stack);
2898 return (1);
2899 }
2900
2901 /* Call this whenever the structure of the witness graph changes. */
2902 static void
2903 witness_increment_graph_generation(void)
2904 {
2905
2906 if (witness_cold == 0)
2907 mtx_assert(&w_mtx, MA_OWNED);
2908 w_generation++;
2909 }
2910
2911 #ifdef KDB
2912 static void
2913 _witness_debugger(int cond, const char *msg)
2914 {
2915
2916 if (witness_trace && cond)
2917 kdb_backtrace();
2918 if (witness_kdb && cond)
2919 kdb_enter(KDB_WHY_WITNESS, msg);
2920 }
2921 #endif
Cache object: 42954fd892aa79b2fa09a24584d5eeef
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