FreeBSD kernel kern code
subr_witness.c
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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("$FreeBSD$");
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#define LI_SLEEPABLE 0x00040000 /* Lock may be held while sleeping. */
135
136#ifndef WITNESS_COUNT
137#define WITNESS_COUNT 1536
138#endif
139#define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */
140#define WITNESS_PENDLIST (512 + (MAXCPU * 4))
141
142/* Allocate 256 KB of stack data space */
143#define WITNESS_LO_DATA_COUNT 2048
144
145/* Prime, gives load factor of ~2 at full load */
146#define WITNESS_LO_HASH_SIZE 1021
147
148/*
149 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads
150 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should
151 * probably be safe for the most part, but it's still a SWAG.
152 */
153#define LOCK_NCHILDREN 5
154#define LOCK_CHILDCOUNT 2048
155
156#define MAX_W_NAME 64
157
158#define FULLGRAPH_SBUF_SIZE 512
159
160/*
161 * These flags go in the witness relationship matrix and describe the
162 * relationship between any two struct witness objects.
163 */
164#define WITNESS_UNRELATED 0x00 /* No lock order relation. */
165#define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */
166#define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */
167#define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */
168#define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */
169#define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR)
170#define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT)
171#define WITNESS_RELATED_MASK \
172 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK)
173#define WITNESS_REVERSAL 0x10 /* A lock order reversal has been
174 * observed. */
175#define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */
176#define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */
177#define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */
178
179/* Descendant to ancestor flags */
180#define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2)
181
182/* Ancestor to descendant flags */
183#define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2)
184
185#define WITNESS_INDEX_ASSERT(i) \
186 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < witness_count)
187
188static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness");
189
190/*
191 * Lock instances. A lock instance is the data associated with a lock while
192 * it is held by witness. For example, a lock instance will hold the
193 * recursion count of a lock. Lock instances are held in lists. Spin locks
194 * are held in a per-cpu list while sleep locks are held in per-thread list.
195 */
196struct lock_instance {
197 struct lock_object *li_lock;
198 const char *li_file;
199 int li_line;
200 u_int li_flags;
201};
202
203/*
204 * A simple list type used to build the list of locks held by a thread
205 * or CPU. We can't simply embed the list in struct lock_object since a
206 * lock may be held by more than one thread if it is a shared lock. Locks
207 * are added to the head of the list, so we fill up each list entry from
208 * "the back" logically. To ease some of the arithmetic, we actually fill
209 * in each list entry the normal way (children[0] then children[1], etc.) but
210 * when we traverse the list we read children[count-1] as the first entry
211 * down to children[0] as the final entry.
212 */
213struct lock_list_entry {
214 struct lock_list_entry *ll_next;
215 struct lock_instance ll_children[LOCK_NCHILDREN];
216 u_int ll_count;
217};
218
219/*
220 * The main witness structure. One of these per named lock type in the system
221 * (for example, "vnode interlock").
222 */
223struct witness {
224 char w_name[MAX_W_NAME];
225 uint32_t w_index; /* Index in the relationship matrix */
226 struct lock_class *w_class;
227 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */
228 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */
229 struct witness *w_hash_next; /* Linked list in hash buckets. */
230 const char *w_file; /* File where last acquired */
231 uint32_t w_line; /* Line where last acquired */
232 uint32_t w_refcount;
233 uint16_t w_num_ancestors; /* direct/indirect
234 * ancestor count */
235 uint16_t w_num_descendants; /* direct/indirect
236 * descendant count */
237 int16_t w_ddb_level;
238 unsigned w_displayed:1;
239 unsigned w_reversed:1;
240};
241
242STAILQ_HEAD(witness_list, witness);
243
244/*
245 * The witness hash table. Keys are witness names (const char *), elements are
246 * witness objects (struct witness *).
247 */
248struct witness_hash {
249 struct witness *wh_array[WITNESS_HASH_SIZE];
250 uint32_t wh_size;
251 uint32_t wh_count;
252};
253
254/*
255 * Key type for the lock order data hash table.
256 */
257struct witness_lock_order_key {
258 uint16_t from;
259 uint16_t to;
260};
261
262struct witness_lock_order_data {
263 struct stack wlod_stack;
264 struct witness_lock_order_key wlod_key;
265 struct witness_lock_order_data *wlod_next;
266};
267
268/*
269 * The witness lock order data hash table. Keys are witness index tuples
270 * (struct witness_lock_order_key), elements are lock order data objects
271 * (struct witness_lock_order_data).
272 */
273struct witness_lock_order_hash {
274 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE];
275 u_int wloh_size;
276 u_int wloh_count;
277};
278
279struct witness_blessed {
280 const char *b_lock1;
281 const char *b_lock2;
282};
283
284struct witness_pendhelp {
285 const char *wh_type;
286 struct lock_object *wh_lock;
287};
288
289struct witness_order_list_entry {
290 const char *w_name;
291 struct lock_class *w_class;
292};
293
294/*
295 * Returns 0 if one of the locks is a spin lock and the other is not.
296 * Returns 1 otherwise.
297 */
298static __inline int
299witness_lock_type_equal(struct witness *w1, struct witness *w2)
300{
301
302 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) ==
303 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)));
304}
305
306static __inline int
307witness_lock_order_key_equal(const struct witness_lock_order_key *a,
308 const struct witness_lock_order_key *b)
309{
310
311 return (a->from == b->from && a->to == b->to);
312}
313
314static int _isitmyx(struct witness *w1, struct witness *w2, int rmask,
315 const char *fname);
316static void adopt(struct witness *parent, struct witness *child);
317static int blessed(struct witness *, struct witness *);
318static void depart(struct witness *w);
319static struct witness *enroll(const char *description,
320 struct lock_class *lock_class);
321static struct lock_instance *find_instance(struct lock_list_entry *list,
322 const struct lock_object *lock);
323static int isitmychild(struct witness *parent, struct witness *child);
324static int isitmydescendant(struct witness *parent, struct witness *child);
325static void itismychild(struct witness *parent, struct witness *child);
326static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS);
327static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS);
328static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS);
329static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS);
330static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent);
331#ifdef DDB
332static void witness_ddb_compute_levels(void);
333static void witness_ddb_display(int(*)(const char *fmt, ...));
334static void witness_ddb_display_descendants(int(*)(const char *fmt, ...),
335 struct witness *, int indent);
336static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...),
337 struct witness_list *list);
338static void witness_ddb_level_descendants(struct witness *parent, int l);
339static void witness_ddb_list(struct thread *td);
340#endif
341static void witness_enter_debugger(const char *msg);
342static void witness_debugger(int cond, const char *msg);
343static void witness_free(struct witness *m);
344static struct witness *witness_get(void);
345static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size);
346static struct witness *witness_hash_get(const char *key);
347static void witness_hash_put(struct witness *w);
348static void witness_init_hash_tables(void);
349static void witness_increment_graph_generation(void);
350static void witness_lock_list_free(struct lock_list_entry *lle);
351static struct lock_list_entry *witness_lock_list_get(void);
352static int witness_lock_order_add(struct witness *parent,
353 struct witness *child);
354static int witness_lock_order_check(struct witness *parent,
355 struct witness *child);
356static struct witness_lock_order_data *witness_lock_order_get(
357 struct witness *parent,
358 struct witness *child);
359static void witness_list_lock(struct lock_instance *instance,
360 int (*prnt)(const char *fmt, ...));
361static int witness_output(const char *fmt, ...) __printflike(1, 2);
362static int witness_output_drain(void *arg __unused, const char *data,
363 int len);
364static int witness_voutput(const char *fmt, va_list ap) __printflike(1, 0);
365static void witness_setflag(struct lock_object *lock, int flag, int set);
366
367FEATURE(witness, "kernel has witness(9) support");
368
369static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW | CTLFLAG_MPSAFE, NULL,
370 "Witness Locking");
371
372/*
373 * If set to 0, lock order checking is disabled. If set to -1,
374 * witness is completely disabled. Otherwise witness performs full
375 * lock order checking for all locks. At runtime, lock order checking
376 * may be toggled. However, witness cannot be reenabled once it is
377 * completely disabled.
378 */
379static int witness_watch = 1;
380SYSCTL_PROC(_debug_witness, OID_AUTO, watch,
381 CTLFLAG_RWTUN | CTLTYPE_INT | CTLFLAG_MPSAFE, NULL, 0,
382 sysctl_debug_witness_watch, "I",
383 "witness is watching lock operations");
384
385#ifdef KDB
386/*
387 * When KDB is enabled and witness_kdb is 1, it will cause the system
388 * to drop into kdebug() when:
389 * - a lock hierarchy violation occurs
390 * - locks are held when going to sleep.
391 */
392#ifdef WITNESS_KDB
393int witness_kdb = 1;
394#else
395int witness_kdb = 0;
396#endif
397SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RWTUN, &witness_kdb, 0, "");
398#endif /* KDB */
399
400#if defined(DDB) || defined(KDB)
401/*
402 * When DDB or KDB is enabled and witness_trace is 1, it will cause the system
403 * to print a stack trace:
404 * - a lock hierarchy violation occurs
405 * - locks are held when going to sleep.
406 */
407int witness_trace = 1;
408SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RWTUN, &witness_trace, 0, "");
409#endif /* DDB || KDB */
410
411#ifdef WITNESS_SKIPSPIN
412int witness_skipspin = 1;
413#else
414int witness_skipspin = 0;
415#endif
416SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, "");
417
418int badstack_sbuf_size;
419
420int witness_count = WITNESS_COUNT;
421SYSCTL_INT(_debug_witness, OID_AUTO, witness_count, CTLFLAG_RDTUN,
422 &witness_count, 0, "");
423
424/*
425 * Output channel for witness messages. By default we print to the console.
426 */
427enum witness_channel {
428 WITNESS_CONSOLE,
429 WITNESS_LOG,
430 WITNESS_NONE,
431};
432
433static enum witness_channel witness_channel = WITNESS_CONSOLE;
434SYSCTL_PROC(_debug_witness, OID_AUTO, output_channel,
435 CTLTYPE_STRING | CTLFLAG_RWTUN | CTLFLAG_MPSAFE, NULL, 0,
436 sysctl_debug_witness_channel, "A",
437 "Output channel for warnings");
438
439/*
440 * Call this to print out the relations between locks.
441 */
442SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph,
443 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
444 sysctl_debug_witness_fullgraph, "A",
445 "Show locks relation graphs");
446
447/*
448 * Call this to print out the witness faulty stacks.
449 */
450SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks,
451 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_MPSAFE, NULL, 0,
452 sysctl_debug_witness_badstacks, "A",
453 "Show bad witness stacks");
454
455static struct mtx w_mtx;
456
457/* w_list */
458static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free);
459static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all);
460
461/* w_typelist */
462static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin);
463static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep);
464
465/* lock list */
466static struct lock_list_entry *w_lock_list_free = NULL;
467static struct witness_pendhelp pending_locks[WITNESS_PENDLIST];
468static u_int pending_cnt;
469
470static int w_free_cnt, w_spin_cnt, w_sleep_cnt;
471SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, "");
472SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, "");
473SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0,
474 "");
475
476static struct witness *w_data;
477static uint8_t **w_rmatrix;
478static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT];
479static struct witness_hash w_hash; /* The witness hash table. */
480
481/* The lock order data hash */
482static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT];
483static struct witness_lock_order_data *w_lofree = NULL;
484static struct witness_lock_order_hash w_lohash;
485static int w_max_used_index = 0;
486static unsigned int w_generation = 0;
487static const char w_notrunning[] = "Witness not running\n";
488static const char w_stillcold[] = "Witness is still cold\n";
489#ifdef __i386__
490static const char w_notallowed[] = "The sysctl is disabled on the arch\n";
491#endif
492
493static struct witness_order_list_entry order_lists[] = {
494 /*
495 * sx locks
496 */
497 { "proctree", &lock_class_sx },
498 { "allproc", &lock_class_sx },
499 { "allprison", &lock_class_sx },
500 { NULL, NULL },
501 /*
502 * Various mutexes
503 */
504 { "Giant", &lock_class_mtx_sleep },
505 { "pipe mutex", &lock_class_mtx_sleep },
506 { "sigio lock", &lock_class_mtx_sleep },
507 { "process group", &lock_class_mtx_sleep },
508#ifdef HWPMC_HOOKS
509 { "pmc-sleep", &lock_class_mtx_sleep },
510#endif
511 { "process lock", &lock_class_mtx_sleep },
512 { "session", &lock_class_mtx_sleep },
513 { "uidinfo hash", &lock_class_rw },
514 { "time lock", &lock_class_mtx_sleep },
515 { NULL, NULL },
516 /*
517 * umtx
518 */
519 { "umtx lock", &lock_class_mtx_sleep },
520 { NULL, NULL },
521 /*
522 * Sockets
523 */
524 { "accept", &lock_class_mtx_sleep },
525 { "so_snd", &lock_class_mtx_sleep },
526 { "so_rcv", &lock_class_mtx_sleep },
527 { "sellck", &lock_class_mtx_sleep },
528 { NULL, NULL },
529 /*
530 * Routing
531 */
532 { "so_rcv", &lock_class_mtx_sleep },
533 { "radix node head", &lock_class_rm },
534 { "ifaddr", &lock_class_mtx_sleep },
535 { NULL, NULL },
536 /*
537 * IPv4 multicast:
538 * protocol locks before interface locks, after UDP locks.
539 */
540 { "in_multi_sx", &lock_class_sx },
541 { "udpinp", &lock_class_rw },
542 { "in_multi_list_mtx", &lock_class_mtx_sleep },
543 { "igmp_mtx", &lock_class_mtx_sleep },
544 { "if_addr_lock", &lock_class_mtx_sleep },
545 { NULL, NULL },
546 /*
547 * IPv6 multicast:
548 * protocol locks before interface locks, after UDP locks.
549 */
550 { "in6_multi_sx", &lock_class_sx },
551 { "udpinp", &lock_class_rw },
552 { "in6_multi_list_mtx", &lock_class_mtx_sleep },
553 { "mld_mtx", &lock_class_mtx_sleep },
554 { "if_addr_lock", &lock_class_mtx_sleep },
555 { NULL, NULL },
556 /*
557 * UNIX Domain Sockets
558 */
559 { "unp_link_rwlock", &lock_class_rw },
560 { "unp_list_lock", &lock_class_mtx_sleep },
561 { "unp", &lock_class_mtx_sleep },
562 { "so_snd", &lock_class_mtx_sleep },
563 { NULL, NULL },
564 /*
565 * UDP/IP
566 */
567 { "udpinp", &lock_class_rw },
568 { "udp", &lock_class_mtx_sleep },
569 { "so_snd", &lock_class_mtx_sleep },
570 { NULL, NULL },
571 /*
572 * TCP/IP
573 */
574 { "tcpinp", &lock_class_rw },
575 { "tcp", &lock_class_mtx_sleep },
576 { "so_snd", &lock_class_mtx_sleep },
577 { NULL, NULL },
578 /*
579 * BPF
580 */
581 { "bpf global lock", &lock_class_sx },
582 { "bpf cdev lock", &lock_class_mtx_sleep },
583 { NULL, NULL },
584 /*
585 * NFS server
586 */
587 { "nfsd_mtx", &lock_class_mtx_sleep },
588 { "so_snd", &lock_class_mtx_sleep },
589 { NULL, NULL },
590
591 /*
592 * IEEE 802.11
593 */
594 { "802.11 com lock", &lock_class_mtx_sleep},
595 { NULL, NULL },
596 /*
597 * Network drivers
598 */
599 { "network driver", &lock_class_mtx_sleep},
600 { NULL, NULL },
601
602 /*
603 * Netgraph
604 */
605 { "ng_node", &lock_class_mtx_sleep },
606 { "ng_worklist", &lock_class_mtx_sleep },
607 { NULL, NULL },
608 /*
609 * CDEV
610 */
611 { "vm map (system)", &lock_class_mtx_sleep },
612 { "vnode interlock", &lock_class_mtx_sleep },
613 { "cdev", &lock_class_mtx_sleep },
614 { "devthrd", &lock_class_mtx_sleep },
615 { NULL, NULL },
616 /*
617 * VM
618 */
619 { "vm map (user)", &lock_class_sx },
620 { "vm object", &lock_class_rw },
621 { "vm page", &lock_class_mtx_sleep },
622 { "pmap pv global", &lock_class_rw },
623 { "pmap", &lock_class_mtx_sleep },
624 { "pmap pv list", &lock_class_rw },
625 { "vm page free queue", &lock_class_mtx_sleep },
626 { "vm pagequeue", &lock_class_mtx_sleep },
627 { NULL, NULL },
628 /*
629 * kqueue/VFS interaction
630 */
631 { "kqueue", &lock_class_mtx_sleep },
632 { "struct mount mtx", &lock_class_mtx_sleep },
633 { "vnode interlock", &lock_class_mtx_sleep },
634 { NULL, NULL },
635 /*
636 * VFS namecache
637 */
638 { "ncvn", &lock_class_mtx_sleep },
639 { "ncbuc", &lock_class_mtx_sleep },
640 { "vnode interlock", &lock_class_mtx_sleep },
641 { "ncneg", &lock_class_mtx_sleep },
642 { NULL, NULL },
643 /*
644 * ZFS locking
645 */
646 { "dn->dn_mtx", &lock_class_sx },
647 { "dr->dt.di.dr_mtx", &lock_class_sx },
648 { "db->db_mtx", &lock_class_sx },
649 { NULL, NULL },
650 /*
651 * TCP log locks
652 */
653 { "TCP ID tree", &lock_class_rw },
654 { "tcp log id bucket", &lock_class_mtx_sleep },
655 { "tcpinp", &lock_class_rw },
656 { "TCP log expireq", &lock_class_mtx_sleep },
657 { NULL, NULL },
658 /*
659 * spin locks
660 */
661#ifdef SMP
662 { "ap boot", &lock_class_mtx_spin },
663#endif
664 { "rm.mutex_mtx", &lock_class_mtx_spin },
665#ifdef __i386__
666 { "cy", &lock_class_mtx_spin },
667#endif
668 { "scc_hwmtx", &lock_class_mtx_spin },
669 { "uart_hwmtx", &lock_class_mtx_spin },
670 { "fast_taskqueue", &lock_class_mtx_spin },
671 { "intr table", &lock_class_mtx_spin },
672 { "process slock", &lock_class_mtx_spin },
673 { "syscons video lock", &lock_class_mtx_spin },
674 { "sleepq chain", &lock_class_mtx_spin },
675 { "rm_spinlock", &lock_class_mtx_spin },
676 { "turnstile chain", &lock_class_mtx_spin },
677 { "turnstile lock", &lock_class_mtx_spin },
678 { "sched lock", &lock_class_mtx_spin },
679 { "td_contested", &lock_class_mtx_spin },
680 { "callout", &lock_class_mtx_spin },
681 { "entropy harvest mutex", &lock_class_mtx_spin },
682#ifdef SMP
683 { "smp rendezvous", &lock_class_mtx_spin },
684#endif
685#ifdef __powerpc__
686 { "tlb0", &lock_class_mtx_spin },
687#endif
688 { NULL, NULL },
689 { "sched lock", &lock_class_mtx_spin },
690#ifdef HWPMC_HOOKS
691 { "pmc-per-proc", &lock_class_mtx_spin },
692#endif
693 { NULL, NULL },
694 /*
695 * leaf locks
696 */
697 { "intrcnt", &lock_class_mtx_spin },
698 { "icu", &lock_class_mtx_spin },
699#ifdef __i386__
700 { "allpmaps", &lock_class_mtx_spin },
701 { "descriptor tables", &lock_class_mtx_spin },
702#endif
703 { "clk", &lock_class_mtx_spin },
704 { "cpuset", &lock_class_mtx_spin },
705 { "mprof lock", &lock_class_mtx_spin },
706 { "zombie lock", &lock_class_mtx_spin },
707 { "ALD Queue", &lock_class_mtx_spin },
708#if defined(__i386__) || defined(__amd64__)
709 { "pcicfg", &lock_class_mtx_spin },
710 { "NDIS thread lock", &lock_class_mtx_spin },
711#endif
712 { "tw_osl_io_lock", &lock_class_mtx_spin },
713 { "tw_osl_q_lock", &lock_class_mtx_spin },
714 { "tw_cl_io_lock", &lock_class_mtx_spin },
715 { "tw_cl_intr_lock", &lock_class_mtx_spin },
716 { "tw_cl_gen_lock", &lock_class_mtx_spin },
717#ifdef HWPMC_HOOKS
718 { "pmc-leaf", &lock_class_mtx_spin },
719#endif
720 { "blocked lock", &lock_class_mtx_spin },
721 { NULL, NULL },
722 { NULL, NULL }
723};
724
725/*
726 * Pairs of locks which have been blessed. Witness does not complain about
727 * order problems with blessed lock pairs. Please do not add an entry to the
728 * table without an explanatory comment.
729 */
730static struct witness_blessed blessed_list[] = {
731 /*
732 * See the comment in ufs_dirhash.c. Basically, a vnode lock serializes
733 * both lock orders, so a deadlock cannot happen as a result of this
734 * LOR.
735 */
736 { "dirhash", "bufwait" },
737
738 /*
739 * A UFS vnode may be locked in vget() while a buffer belonging to the
740 * parent directory vnode is locked.
741 */
742 { "ufs", "bufwait" },
743};
744
745/*
746 * This global is set to 0 once it becomes safe to use the witness code.
747 */
748static int witness_cold = 1;
749
750/*
751 * This global is set to 1 once the static lock orders have been enrolled
752 * so that a warning can be issued for any spin locks enrolled later.
753 */
754static int witness_spin_warn = 0;
755
756/* Trim useless garbage from filenames. */
757static const char *
758fixup_filename(const char *file)
759{
760
761 if (file == NULL)
762 return (NULL);
763 while (strncmp(file, "../", 3) == 0)
764 file += 3;
765 return (file);
766}
767
768/*
769 * Calculate the size of early witness structures.
770 */
771int
772witness_startup_count(void)
773{
774 int sz;
775
776 sz = sizeof(struct witness) * witness_count;
777 sz += sizeof(*w_rmatrix) * (witness_count + 1);
778 sz += sizeof(*w_rmatrix[0]) * (witness_count + 1) *
779 (witness_count + 1);
780
781 return (sz);
782}
783
784/*
785 * The WITNESS-enabled diagnostic code. Note that the witness code does
786 * assume that the early boot is single-threaded at least until after this
787 * routine is completed.
788 */
789void
790witness_startup(void *mem)
791{
792 struct lock_object *lock;
793 struct witness_order_list_entry *order;
794 struct witness *w, *w1;
795 uintptr_t p;
796 int i;
797
798 p = (uintptr_t)mem;
799 w_data = (void *)p;
800 p += sizeof(struct witness) * witness_count;
801
802 w_rmatrix = (void *)p;
803 p += sizeof(*w_rmatrix) * (witness_count + 1);
804
805 for (i = 0; i < witness_count + 1; i++) {
806 w_rmatrix[i] = (void *)p;
807 p += sizeof(*w_rmatrix[i]) * (witness_count + 1);
808 }
809 badstack_sbuf_size = witness_count * 256;
810
811 /*
812 * We have to release Giant before initializing its witness
813 * structure so that WITNESS doesn't get confused.
814 */
815 mtx_unlock(&Giant);
816 mtx_assert(&Giant, MA_NOTOWNED);
817
818 CTR1(KTR_WITNESS, "%s: initializing witness", __func__);
819 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET |
820 MTX_NOWITNESS | MTX_NOPROFILE);
821 for (i = witness_count - 1; i >= 0; i--) {
822 w = &w_data[i];
823 memset(w, 0, sizeof(*w));
824 w_data[i].w_index = i; /* Witness index never changes. */
825 witness_free(w);
826 }
827 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0,
828 ("%s: Invalid list of free witness objects", __func__));
829
830 /* Witness with index 0 is not used to aid in debugging. */
831 STAILQ_REMOVE_HEAD(&w_free, w_list);
832 w_free_cnt--;
833
834 for (i = 0; i < witness_count; i++) {
835 memset(w_rmatrix[i], 0, sizeof(*w_rmatrix[i]) *
836 (witness_count + 1));
837 }
838
839 for (i = 0; i < LOCK_CHILDCOUNT; i++)
840 witness_lock_list_free(&w_locklistdata[i]);
841 witness_init_hash_tables();
842
843 /* First add in all the specified order lists. */
844 for (order = order_lists; order->w_name != NULL; order++) {
845 w = enroll(order->w_name, order->w_class);
846 if (w == NULL)
847 continue;
848 w->w_file = "order list";
849 for (order++; order->w_name != NULL; order++) {
850 w1 = enroll(order->w_name, order->w_class);
851 if (w1 == NULL)
852 continue;
853 w1->w_file = "order list";
854 itismychild(w, w1);
855 w = w1;
856 }
857 }
858 witness_spin_warn = 1;
859
860 /* Iterate through all locks and add them to witness. */
861 for (i = 0; pending_locks[i].wh_lock != NULL; i++) {
862 lock = pending_locks[i].wh_lock;
863 KASSERT(lock->lo_flags & LO_WITNESS,
864 ("%s: lock %s is on pending list but not LO_WITNESS",
865 __func__, lock->lo_name));
866 lock->lo_witness = enroll(pending_locks[i].wh_type,
867 LOCK_CLASS(lock));
868 }
869
870 /* Mark the witness code as being ready for use. */
871 witness_cold = 0;
872
873 mtx_lock(&Giant);
874}
875
876void
877witness_init(struct lock_object *lock, const char *type)
878{
879 struct lock_class *class;
880
881 /* Various sanity checks. */
882 class = LOCK_CLASS(lock);
883 if ((lock->lo_flags & LO_RECURSABLE) != 0 &&
884 (class->lc_flags & LC_RECURSABLE) == 0)
885 kassert_panic("%s: lock (%s) %s can not be recursable",
886 __func__, class->lc_name, lock->lo_name);
887 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
888 (class->lc_flags & LC_SLEEPABLE) == 0)
889 kassert_panic("%s: lock (%s) %s can not be sleepable",
890 __func__, class->lc_name, lock->lo_name);
891 if ((lock->lo_flags & LO_UPGRADABLE) != 0 &&
892 (class->lc_flags & LC_UPGRADABLE) == 0)
893 kassert_panic("%s: lock (%s) %s can not be upgradable",
894 __func__, class->lc_name, lock->lo_name);
895
896 /*
897 * If we shouldn't watch this lock, then just clear lo_witness.
898 * Otherwise, if witness_cold is set, then it is too early to
899 * enroll this lock, so defer it to witness_initialize() by adding
900 * it to the pending_locks list. If it is not too early, then enroll
901 * the lock now.
902 */
903 if (witness_watch < 1 || KERNEL_PANICKED() ||
904 (lock->lo_flags & LO_WITNESS) == 0)
905 lock->lo_witness = NULL;
906 else if (witness_cold) {
907 pending_locks[pending_cnt].wh_lock = lock;
908 pending_locks[pending_cnt++].wh_type = type;
909 if (pending_cnt > WITNESS_PENDLIST)
910 panic("%s: pending locks list is too small, "
911 "increase WITNESS_PENDLIST\n",
912 __func__);
913 } else
914 lock->lo_witness = enroll(type, class);
915}
916
917void
918witness_destroy(struct lock_object *lock)
919{
920 struct lock_class *class;
921 struct witness *w;
922
923 class = LOCK_CLASS(lock);
924
925 if (witness_cold)
926 panic("lock (%s) %s destroyed while witness_cold",
927 class->lc_name, lock->lo_name);
928
929 /* XXX: need to verify that no one holds the lock */
930 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL)
931 return;
932 w = lock->lo_witness;
933
934 mtx_lock_spin(&w_mtx);
935 MPASS(w->w_refcount > 0);
936 w->w_refcount--;
937
938 if (w->w_refcount == 0)
939 depart(w);
940 mtx_unlock_spin(&w_mtx);
941}
942
943#ifdef DDB
944static void
945witness_ddb_compute_levels(void)
946{
947 struct witness *w;
948
949 /*
950 * First clear all levels.
951 */
952 STAILQ_FOREACH(w, &w_all, w_list)
953 w->w_ddb_level = -1;
954
955 /*
956 * Look for locks with no parents and level all their descendants.
957 */
958 STAILQ_FOREACH(w, &w_all, w_list) {
959 /* If the witness has ancestors (is not a root), skip it. */
960 if (w->w_num_ancestors > 0)
961 continue;
962 witness_ddb_level_descendants(w, 0);
963 }
964}
965
966static void
967witness_ddb_level_descendants(struct witness *w, int l)
968{
969 int i;
970
971 if (w->w_ddb_level >= l)
972 return;
973
974 w->w_ddb_level = l;
975 l++;
976
977 for (i = 1; i <= w_max_used_index; i++) {
978 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT)
979 witness_ddb_level_descendants(&w_data[i], l);
980 }
981}
982
983static void
984witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...),
985 struct witness *w, int indent)
986{
987 int i;
988
989 for (i = 0; i < indent; i++)
990 prnt(" ");
991 prnt("%s (type: %s, depth: %d, active refs: %d)",
992 w->w_name, w->w_class->lc_name,
993 w->w_ddb_level, w->w_refcount);
994 if (w->w_displayed) {
995 prnt(" -- (already displayed)\n");
996 return;
997 }
998 w->w_displayed = 1;
999 if (w->w_file != NULL && w->w_line != 0)
1000 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file),
1001 w->w_line);
1002 else
1003 prnt(" -- never acquired\n");
1004 indent++;
1005 WITNESS_INDEX_ASSERT(w->w_index);
1006 for (i = 1; i <= w_max_used_index; i++) {
1007 if (db_pager_quit)
1008 return;
1009 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT)
1010 witness_ddb_display_descendants(prnt, &w_data[i],
1011 indent);
1012 }
1013}
1014
1015static void
1016witness_ddb_display_list(int(*prnt)(const char *fmt, ...),
1017 struct witness_list *list)
1018{
1019 struct witness *w;
1020
1021 STAILQ_FOREACH(w, list, w_typelist) {
1022 if (w->w_file == NULL || w->w_ddb_level > 0)
1023 continue;
1024
1025 /* This lock has no anscestors - display its descendants. */
1026 witness_ddb_display_descendants(prnt, w, 0);
1027 if (db_pager_quit)
1028 return;
1029 }
1030}
1031
1032static void
1033witness_ddb_display(int(*prnt)(const char *fmt, ...))
1034{
1035 struct witness *w;
1036
1037 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1038 witness_ddb_compute_levels();
1039
1040 /* Clear all the displayed flags. */
1041 STAILQ_FOREACH(w, &w_all, w_list)
1042 w->w_displayed = 0;
1043
1044 /*
1045 * First, handle sleep locks which have been acquired at least
1046 * once.
1047 */
1048 prnt("Sleep locks:\n");
1049 witness_ddb_display_list(prnt, &w_sleep);
1050 if (db_pager_quit)
1051 return;
1052
1053 /*
1054 * Now do spin locks which have been acquired at least once.
1055 */
1056 prnt("\nSpin locks:\n");
1057 witness_ddb_display_list(prnt, &w_spin);
1058 if (db_pager_quit)
1059 return;
1060
1061 /*
1062 * Finally, any locks which have not been acquired yet.
1063 */
1064 prnt("\nLocks which were never acquired:\n");
1065 STAILQ_FOREACH(w, &w_all, w_list) {
1066 if (w->w_file != NULL || w->w_refcount == 0)
1067 continue;
1068 prnt("%s (type: %s, depth: %d)\n", w->w_name,
1069 w->w_class->lc_name, w->w_ddb_level);
1070 if (db_pager_quit)
1071 return;
1072 }
1073}
1074#endif /* DDB */
1075
1076int
1077witness_defineorder(struct lock_object *lock1, struct lock_object *lock2)
1078{
1079
1080 if (witness_watch == -1 || KERNEL_PANICKED())
1081 return (0);
1082
1083 /* Require locks that witness knows about. */
1084 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL ||
1085 lock2->lo_witness == NULL)
1086 return (EINVAL);
1087
1088 mtx_assert(&w_mtx, MA_NOTOWNED);
1089 mtx_lock_spin(&w_mtx);
1090
1091 /*
1092 * If we already have either an explicit or implied lock order that
1093 * is the other way around, then return an error.
1094 */
1095 if (witness_watch &&
1096 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) {
1097 mtx_unlock_spin(&w_mtx);
1098 return (EDOOFUS);
1099 }
1100
1101 /* Try to add the new order. */
1102 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
1103 lock2->lo_witness->w_name, lock1->lo_witness->w_name);
1104 itismychild(lock1->lo_witness, lock2->lo_witness);
1105 mtx_unlock_spin(&w_mtx);
1106 return (0);
1107}
1108
1109void
1110witness_checkorder(struct lock_object *lock, int flags, const char *file,
1111 int line, struct lock_object *interlock)
1112{
1113 struct lock_list_entry *lock_list, *lle;
1114 struct lock_instance *lock1, *lock2, *plock;
1115 struct lock_class *class, *iclass;
1116 struct witness *w, *w1;
1117 struct thread *td;
1118 int i, j;
1119
1120 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL ||
1121 KERNEL_PANICKED())
1122 return;
1123
1124 w = lock->lo_witness;
1125 class = LOCK_CLASS(lock);
1126 td = curthread;
1127
1128 if (class->lc_flags & LC_SLEEPLOCK) {
1129 /*
1130 * Since spin locks include a critical section, this check
1131 * implicitly enforces a lock order of all sleep locks before
1132 * all spin locks.
1133 */
1134 if (td->td_critnest != 0 && !kdb_active)
1135 kassert_panic("acquiring blockable sleep lock with "
1136 "spinlock or critical section held (%s) %s @ %s:%d",
1137 class->lc_name, lock->lo_name,
1138 fixup_filename(file), line);
1139
1140 /*
1141 * If this is the first lock acquired then just return as
1142 * no order checking is needed.
1143 */
1144 lock_list = td->td_sleeplocks;
1145 if (lock_list == NULL || lock_list->ll_count == 0)
1146 return;
1147 } else {
1148 /*
1149 * If this is the first lock, just return as no order
1150 * checking is needed. Avoid problems with thread
1151 * migration pinning the thread while checking if
1152 * spinlocks are held. If at least one spinlock is held
1153 * the thread is in a safe path and it is allowed to
1154 * unpin it.
1155 */
1156 sched_pin();
1157 lock_list = PCPU_GET(spinlocks);
1158 if (lock_list == NULL || lock_list->ll_count == 0) {
1159 sched_unpin();
1160 return;
1161 }
1162 sched_unpin();
1163 }
1164
1165 /*
1166 * Check to see if we are recursing on a lock we already own. If
1167 * so, make sure that we don't mismatch exclusive and shared lock
1168 * acquires.
1169 */
1170 lock1 = find_instance(lock_list, lock);
1171 if (lock1 != NULL) {
1172 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 &&
1173 (flags & LOP_EXCLUSIVE) == 0) {
1174 witness_output("shared lock of (%s) %s @ %s:%d\n",
1175 class->lc_name, lock->lo_name,
1176 fixup_filename(file), line);
1177 witness_output("while exclusively locked from %s:%d\n",
1178 fixup_filename(lock1->li_file), lock1->li_line);
1179 kassert_panic("excl->share");
1180 }
1181 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 &&
1182 (flags & LOP_EXCLUSIVE) != 0) {
1183 witness_output("exclusive lock of (%s) %s @ %s:%d\n",
1184 class->lc_name, lock->lo_name,
1185 fixup_filename(file), line);
1186 witness_output("while share locked from %s:%d\n",
1187 fixup_filename(lock1->li_file), lock1->li_line);
1188 kassert_panic("share->excl");
1189 }
1190 return;
1191 }
1192
1193 /* Warn if the interlock is not locked exactly once. */
1194 if (interlock != NULL) {
1195 iclass = LOCK_CLASS(interlock);
1196 lock1 = find_instance(lock_list, interlock);
1197 if (lock1 == NULL)
1198 kassert_panic("interlock (%s) %s not locked @ %s:%d",
1199 iclass->lc_name, interlock->lo_name,
1200 fixup_filename(file), line);
1201 else if ((lock1->li_flags & LI_RECURSEMASK) != 0)
1202 kassert_panic("interlock (%s) %s recursed @ %s:%d",
1203 iclass->lc_name, interlock->lo_name,
1204 fixup_filename(file), line);
1205 }
1206
1207 /*
1208 * Find the previously acquired lock, but ignore interlocks.
1209 */
1210 plock = &lock_list->ll_children[lock_list->ll_count - 1];
1211 if (interlock != NULL && plock->li_lock == interlock) {
1212 if (lock_list->ll_count > 1)
1213 plock =
1214 &lock_list->ll_children[lock_list->ll_count - 2];
1215 else {
1216 lle = lock_list->ll_next;
1217
1218 /*
1219 * The interlock is the only lock we hold, so
1220 * simply return.
1221 */
1222 if (lle == NULL)
1223 return;
1224 plock = &lle->ll_children[lle->ll_count - 1];
1225 }
1226 }
1227
1228 /*
1229 * Try to perform most checks without a lock. If this succeeds we
1230 * can skip acquiring the lock and return success. Otherwise we redo
1231 * the check with the lock held to handle races with concurrent updates.
1232 */
1233 w1 = plock->li_lock->lo_witness;
1234 if (witness_lock_order_check(w1, w))
1235 return;
1236
1237 mtx_lock_spin(&w_mtx);
1238 if (witness_lock_order_check(w1, w)) {
1239 mtx_unlock_spin(&w_mtx);
1240 return;
1241 }
1242 witness_lock_order_add(w1, w);
1243
1244 /*
1245 * Check for duplicate locks of the same type. Note that we only
1246 * have to check for this on the last lock we just acquired. Any
1247 * other cases will be caught as lock order violations.
1248 */
1249 if (w1 == w) {
1250 i = w->w_index;
1251 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) &&
1252 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) {
1253 w_rmatrix[i][i] |= WITNESS_REVERSAL;
1254 w->w_reversed = 1;
1255 mtx_unlock_spin(&w_mtx);
1256 witness_output(
1257 "acquiring duplicate lock of same type: \"%s\"\n",
1258 w->w_name);
1259 witness_output(" 1st %s @ %s:%d\n", plock->li_lock->lo_name,
1260 fixup_filename(plock->li_file), plock->li_line);
1261 witness_output(" 2nd %s @ %s:%d\n", lock->lo_name,
1262 fixup_filename(file), line);
1263 witness_debugger(1, __func__);
1264 } else
1265 mtx_unlock_spin(&w_mtx);
1266 return;
1267 }
1268 mtx_assert(&w_mtx, MA_OWNED);
1269
1270 /*
1271 * If we know that the lock we are acquiring comes after
1272 * the lock we most recently acquired in the lock order tree,
1273 * then there is no need for any further checks.
1274 */
1275 if (isitmychild(w1, w))
1276 goto out;
1277
1278 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) {
1279 for (i = lle->ll_count - 1; i >= 0; i--, j++) {
1280 struct stack pstack;
1281 bool pstackv, trace;
1282
1283 MPASS(j < LOCK_CHILDCOUNT * LOCK_NCHILDREN);
1284 lock1 = &lle->ll_children[i];
1285
1286 /*
1287 * Ignore the interlock.
1288 */
1289 if (interlock == lock1->li_lock)
1290 continue;
1291
1292 /*
1293 * If this lock doesn't undergo witness checking,
1294 * then skip it.
1295 */
1296 w1 = lock1->li_lock->lo_witness;
1297 if (w1 == NULL) {
1298 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0,
1299 ("lock missing witness structure"));
1300 continue;
1301 }
1302
1303 /*
1304 * If we are locking Giant and this is a sleepable
1305 * lock, then skip it.
1306 */
1307 if ((lock1->li_flags & LI_SLEEPABLE) != 0 &&
1308 lock == &Giant.lock_object)
1309 continue;
1310
1311 /*
1312 * If we are locking a sleepable lock and this lock
1313 * is Giant, then skip it.
1314 */
1315 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1316 (flags & LOP_NOSLEEP) == 0 &&
1317 lock1->li_lock == &Giant.lock_object)
1318 continue;
1319
1320 /*
1321 * If we are locking a sleepable lock and this lock
1322 * isn't sleepable, we want to treat it as a lock
1323 * order violation to enfore a general lock order of
1324 * sleepable locks before non-sleepable locks.
1325 */
1326 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1327 (flags & LOP_NOSLEEP) == 0 &&
1328 (lock1->li_flags & LI_SLEEPABLE) == 0)
1329 goto reversal;
1330
1331 /*
1332 * If we are locking Giant and this is a non-sleepable
1333 * lock, then treat it as a reversal.
1334 */
1335 if ((lock1->li_flags & LI_SLEEPABLE) == 0 &&
1336 lock == &Giant.lock_object)
1337 goto reversal;
1338
1339 /*
1340 * Check the lock order hierarchy for a reveresal.
1341 */
1342 if (!isitmydescendant(w, w1))
1343 continue;
1344 reversal:
1345
1346 /*
1347 * We have a lock order violation, check to see if it
1348 * is allowed or has already been yelled about.
1349 */
1350
1351 /* Bail if this violation is known */
1352 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL)
1353 goto out;
1354
1355 /* Record this as a violation */
1356 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL;
1357 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL;
1358 w->w_reversed = w1->w_reversed = 1;
1359 witness_increment_graph_generation();
1360
1361 /*
1362 * If the lock order is blessed, bail before logging
1363 * anything. We don't look for other lock order
1364 * violations though, which may be a bug.
1365 */
1366 if (blessed(w, w1))
1367 goto out;
1368
1369 trace = atomic_load_int(&witness_trace);
1370 if (trace) {
1371 struct witness_lock_order_data *data;
1372
1373 pstackv = false;
1374 data = witness_lock_order_get(w, w1);
1375 if (data != NULL) {
1376 stack_copy(&data->wlod_stack,
1377 &pstack);
1378 pstackv = true;
1379 }
1380 }
1381 mtx_unlock_spin(&w_mtx);
1382
1383#ifdef WITNESS_NO_VNODE
1384 /*
1385 * There are known LORs between VNODE locks. They are
1386 * not an indication of a bug. VNODE locks are flagged
1387 * as such (LO_IS_VNODE) and we don't yell if the LOR
1388 * is between 2 VNODE locks.
1389 */
1390 if ((lock->lo_flags & LO_IS_VNODE) != 0 &&
1391 (lock1->li_lock->lo_flags & LO_IS_VNODE) != 0)
1392 return;
1393#endif
1394
1395 /*
1396 * Ok, yell about it.
1397 */
1398 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1399 (flags & LOP_NOSLEEP) == 0 &&
1400 (lock1->li_flags & LI_SLEEPABLE) == 0)
1401 witness_output(
1402 "lock order reversal: (sleepable after non-sleepable)\n");
1403 else if ((lock1->li_flags & LI_SLEEPABLE) == 0
1404 && lock == &Giant.lock_object)
1405 witness_output(
1406 "lock order reversal: (Giant after non-sleepable)\n");
1407 else
1408 witness_output("lock order reversal:\n");
1409
1410 /*
1411 * Try to locate an earlier lock with
1412 * witness w in our list.
1413 */
1414 do {
1415 lock2 = &lle->ll_children[i];
1416 MPASS(lock2->li_lock != NULL);
1417 if (lock2->li_lock->lo_witness == w)
1418 break;
1419 if (i == 0 && lle->ll_next != NULL) {
1420 lle = lle->ll_next;
1421 i = lle->ll_count - 1;
1422 MPASS(i >= 0 && i < LOCK_NCHILDREN);
1423 } else
1424 i--;
1425 } while (i >= 0);
1426 if (i < 0) {
1427 witness_output(" 1st %p %s (%s, %s) @ %s:%d\n",
1428 lock1->li_lock, lock1->li_lock->lo_name,
1429 w1->w_name, w1->w_class->lc_name,
1430 fixup_filename(lock1->li_file),
1431 lock1->li_line);
1432 witness_output(" 2nd %p %s (%s, %s) @ %s:%d\n",
1433 lock, lock->lo_name, w->w_name,
1434 w->w_class->lc_name, fixup_filename(file),
1435 line);
1436 } else {
1437 struct witness *w2 = lock2->li_lock->lo_witness;
1438
1439 witness_output(" 1st %p %s (%s, %s) @ %s:%d\n",
1440 lock2->li_lock, lock2->li_lock->lo_name,
1441 w2->w_name, w2->w_class->lc_name,
1442 fixup_filename(lock2->li_file),
1443 lock2->li_line);
1444 witness_output(" 2nd %p %s (%s, %s) @ %s:%d\n",
1445 lock1->li_lock, lock1->li_lock->lo_name,
1446 w1->w_name, w1->w_class->lc_name,
1447 fixup_filename(lock1->li_file),
1448 lock1->li_line);
1449 witness_output(" 3rd %p %s (%s, %s) @ %s:%d\n", lock,
1450 lock->lo_name, w->w_name,
1451 w->w_class->lc_name, fixup_filename(file),
1452 line);
1453 }
1454 if (trace) {
1455 char buf[64];
1456 struct sbuf sb;
1457
1458 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN);
1459 sbuf_set_drain(&sb, witness_output_drain,
1460 NULL);
1461
1462 if (pstackv) {
1463 sbuf_printf(&sb,
1464 "lock order %s -> %s established at:\n",
1465 w->w_name, w1->w_name);
1466 stack_sbuf_print_flags(&sb, &pstack,
1467 M_NOWAIT, STACK_SBUF_FMT_LONG);
1468 }
1469
1470 sbuf_printf(&sb,
1471 "lock order %s -> %s attempted at:\n",
1472 w1->w_name, w->w_name);
1473 stack_save(&pstack);
1474 stack_sbuf_print_flags(&sb, &pstack, M_NOWAIT,
1475 STACK_SBUF_FMT_LONG);
1476
1477 sbuf_finish(&sb);
1478 sbuf_delete(&sb);
1479 }
1480 witness_enter_debugger(__func__);
1481 return;
1482 }
1483 }
1484
1485 /*
1486 * If requested, build a new lock order. However, don't build a new
1487 * relationship between a sleepable lock and Giant if it is in the
1488 * wrong direction. The correct lock order is that sleepable locks
1489 * always come before Giant.
1490 */
1491 if (flags & LOP_NEWORDER &&
1492 !(plock->li_lock == &Giant.lock_object &&
1493 (lock->lo_flags & LO_SLEEPABLE) != 0 &&
1494 (flags & LOP_NOSLEEP) == 0)) {
1495 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
1496 w->w_name, plock->li_lock->lo_witness->w_name);
1497 itismychild(plock->li_lock->lo_witness, w);
1498 }
1499out:
1500 mtx_unlock_spin(&w_mtx);
1501}
1502
1503void
1504witness_lock(struct lock_object *lock, int flags, const char *file, int line)
1505{
1506 struct lock_list_entry **lock_list, *lle;
1507 struct lock_instance *instance;
1508 struct witness *w;
1509 struct thread *td;
1510
1511 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL ||
1512 KERNEL_PANICKED())
1513 return;
1514 w = lock->lo_witness;
1515 td = curthread;
1516
1517 /* Determine lock list for this lock. */
1518 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK)
1519 lock_list = &td->td_sleeplocks;
1520 else
1521 lock_list = PCPU_PTR(spinlocks);
1522
1523 /* Check to see if we are recursing on a lock we already own. */
1524 instance = find_instance(*lock_list, lock);
1525 if (instance != NULL) {
1526 instance->li_flags++;
1527 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__,
1528 td->td_proc->p_pid, lock->lo_name,
1529 instance->li_flags & LI_RECURSEMASK);
1530 instance->li_file = file;
1531 instance->li_line = line;
1532 return;
1533 }
1534
1535 /* Update per-witness last file and line acquire. */
1536 w->w_file = file;
1537 w->w_line = line;
1538
1539 /* Find the next open lock instance in the list and fill it. */
1540 lle = *lock_list;
1541 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) {
1542 lle = witness_lock_list_get();
1543 if (lle == NULL)
1544 return;
1545 lle->ll_next = *lock_list;
1546 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__,
1547 td->td_proc->p_pid, lle);
1548 *lock_list = lle;
1549 }
1550 instance = &lle->ll_children[lle->ll_count++];
1551 instance->li_lock = lock;
1552 instance->li_line = line;
1553 instance->li_file = file;
1554 instance->li_flags = 0;
1555 if ((flags & LOP_EXCLUSIVE) != 0)
1556 instance->li_flags |= LI_EXCLUSIVE;
1557 if ((lock->lo_flags & LO_SLEEPABLE) != 0 && (flags & LOP_NOSLEEP) == 0)
1558 instance->li_flags |= LI_SLEEPABLE;
1559 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__,
1560 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1);
1561}
1562
1563void
1564witness_upgrade(struct lock_object *lock, int flags, const char *file, int line)
1565{
1566 struct lock_instance *instance;
1567 struct lock_class *class;
1568
1569 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1570 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED())
1571 return;
1572 class = LOCK_CLASS(lock);
1573 if (witness_watch) {
1574 if ((lock->lo_flags & LO_UPGRADABLE) == 0)
1575 kassert_panic(
1576 "upgrade of non-upgradable lock (%s) %s @ %s:%d",
1577 class->lc_name, lock->lo_name,
1578 fixup_filename(file), line);
1579 if ((class->lc_flags & LC_SLEEPLOCK) == 0)
1580 kassert_panic(
1581 "upgrade of non-sleep lock (%s) %s @ %s:%d",
1582 class->lc_name, lock->lo_name,
1583 fixup_filename(file), line);
1584 }
1585 instance = find_instance(curthread->td_sleeplocks, lock);
1586 if (instance == NULL) {
1587 kassert_panic("upgrade of unlocked lock (%s) %s @ %s:%d",
1588 class->lc_name, lock->lo_name,
1589 fixup_filename(file), line);
1590 return;
1591 }
1592 if (witness_watch) {
1593 if ((instance->li_flags & LI_EXCLUSIVE) != 0)
1594 kassert_panic(
1595 "upgrade of exclusive lock (%s) %s @ %s:%d",
1596 class->lc_name, lock->lo_name,
1597 fixup_filename(file), line);
1598 if ((instance->li_flags & LI_RECURSEMASK) != 0)
1599 kassert_panic(
1600 "upgrade of recursed lock (%s) %s r=%d @ %s:%d",
1601 class->lc_name, lock->lo_name,
1602 instance->li_flags & LI_RECURSEMASK,
1603 fixup_filename(file), line);
1604 }
1605 instance->li_flags |= LI_EXCLUSIVE;
1606}
1607
1608void
1609witness_downgrade(struct lock_object *lock, int flags, const char *file,
1610 int line)
1611{
1612 struct lock_instance *instance;
1613 struct lock_class *class;
1614
1615 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1616 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED())
1617 return;
1618 class = LOCK_CLASS(lock);
1619 if (witness_watch) {
1620 if ((lock->lo_flags & LO_UPGRADABLE) == 0)
1621 kassert_panic(
1622 "downgrade of non-upgradable lock (%s) %s @ %s:%d",
1623 class->lc_name, lock->lo_name,
1624 fixup_filename(file), line);
1625 if ((class->lc_flags & LC_SLEEPLOCK) == 0)
1626 kassert_panic(
1627 "downgrade of non-sleep lock (%s) %s @ %s:%d",
1628 class->lc_name, lock->lo_name,
1629 fixup_filename(file), line);
1630 }
1631 instance = find_instance(curthread->td_sleeplocks, lock);
1632 if (instance == NULL) {
1633 kassert_panic("downgrade of unlocked lock (%s) %s @ %s:%d",
1634 class->lc_name, lock->lo_name,
1635 fixup_filename(file), line);
1636 return;
1637 }
1638 if (witness_watch) {
1639 if ((instance->li_flags & LI_EXCLUSIVE) == 0)
1640 kassert_panic(
1641 "downgrade of shared lock (%s) %s @ %s:%d",
1642 class->lc_name, lock->lo_name,
1643 fixup_filename(file), line);
1644 if ((instance->li_flags & LI_RECURSEMASK) != 0)
1645 kassert_panic(
1646 "downgrade of recursed lock (%s) %s r=%d @ %s:%d",
1647 class->lc_name, lock->lo_name,
1648 instance->li_flags & LI_RECURSEMASK,
1649 fixup_filename(file), line);
1650 }
1651 instance->li_flags &= ~LI_EXCLUSIVE;
1652}
1653
1654void
1655witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
1656{
1657 struct lock_list_entry **lock_list, *lle;
1658 struct lock_instance *instance;
1659 struct lock_class *class;
1660 struct thread *td;
1661 register_t s;
1662 int i, j;
1663
1664 if (witness_cold || lock->lo_witness == NULL || KERNEL_PANICKED())
1665 return;
1666 td = curthread;
1667 class = LOCK_CLASS(lock);
1668
1669 /* Find lock instance associated with this lock. */
1670 if (class->lc_flags & LC_SLEEPLOCK)
1671 lock_list = &td->td_sleeplocks;
1672 else
1673 lock_list = PCPU_PTR(spinlocks);
1674 lle = *lock_list;
1675 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next)
1676 for (i = 0; i < (*lock_list)->ll_count; i++) {
1677 instance = &(*lock_list)->ll_children[i];
1678 if (instance->li_lock == lock)
1679 goto found;
1680 }
1681
1682 /*
1683 * When disabling WITNESS through witness_watch we could end up in
1684 * having registered locks in the td_sleeplocks queue.
1685 * We have to make sure we flush these queues, so just search for
1686 * eventual register locks and remove them.
1687 */
1688 if (witness_watch > 0) {
1689 kassert_panic("lock (%s) %s not locked @ %s:%d", class->lc_name,
1690 lock->lo_name, fixup_filename(file), line);
1691 return;
1692 } else {
1693 return;
1694 }
1695found:
1696
1697 /* First, check for shared/exclusive mismatches. */
1698 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 &&
1699 (flags & LOP_EXCLUSIVE) == 0) {
1700 witness_output("shared unlock of (%s) %s @ %s:%d\n",
1701 class->lc_name, lock->lo_name, fixup_filename(file), line);
1702 witness_output("while exclusively locked from %s:%d\n",
1703 fixup_filename(instance->li_file), instance->li_line);
1704 kassert_panic("excl->ushare");
1705 }
1706 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 &&
1707 (flags & LOP_EXCLUSIVE) != 0) {
1708 witness_output("exclusive unlock of (%s) %s @ %s:%d\n",
1709 class->lc_name, lock->lo_name, fixup_filename(file), line);
1710 witness_output("while share locked from %s:%d\n",
1711 fixup_filename(instance->li_file),
1712 instance->li_line);
1713 kassert_panic("share->uexcl");
1714 }
1715 /* If we are recursed, unrecurse. */
1716 if ((instance->li_flags & LI_RECURSEMASK) > 0) {
1717 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__,
1718 td->td_proc->p_pid, instance->li_lock->lo_name,
1719 instance->li_flags);
1720 instance->li_flags--;
1721 return;
1722 }
1723 /* The lock is now being dropped, check for NORELEASE flag */
1724 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) {
1725 witness_output("forbidden unlock of (%s) %s @ %s:%d\n",
1726 class->lc_name, lock->lo_name, fixup_filename(file), line);
1727 kassert_panic("lock marked norelease");
1728 }
1729
1730 /* Otherwise, remove this item from the list. */
1731 s = intr_disable();
1732 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__,
1733 td->td_proc->p_pid, instance->li_lock->lo_name,
1734 (*lock_list)->ll_count - 1);
1735 for (j = i; j < (*lock_list)->ll_count - 1; j++)
1736 (*lock_list)->ll_children[j] =
1737 (*lock_list)->ll_children[j + 1];
1738 (*lock_list)->ll_count--;
1739 intr_restore(s);
1740
1741 /*
1742 * In order to reduce contention on w_mtx, we want to keep always an
1743 * head object into lists so that frequent allocation from the
1744 * free witness pool (and subsequent locking) is avoided.
1745 * In order to maintain the current code simple, when the head
1746 * object is totally unloaded it means also that we do not have
1747 * further objects in the list, so the list ownership needs to be
1748 * hand over to another object if the current head needs to be freed.
1749 */
1750 if ((*lock_list)->ll_count == 0) {
1751 if (*lock_list == lle) {
1752 if (lle->ll_next == NULL)
1753 return;
1754 } else
1755 lle = *lock_list;
1756 *lock_list = lle->ll_next;
1757 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__,
1758 td->td_proc->p_pid, lle);
1759 witness_lock_list_free(lle);
1760 }
1761}
1762
1763void
1764witness_thread_exit(struct thread *td)
1765{
1766 struct lock_list_entry *lle;
1767 int i, n;
1768
1769 lle = td->td_sleeplocks;
1770 if (lle == NULL || KERNEL_PANICKED())
1771 return;
1772 if (lle->ll_count != 0) {
1773 for (n = 0; lle != NULL; lle = lle->ll_next)
1774 for (i = lle->ll_count - 1; i >= 0; i--) {
1775 if (n == 0)
1776 witness_output(
1777 "Thread %p exiting with the following locks held:\n", td);
1778 n++;
1779 witness_list_lock(&lle->ll_children[i],
1780 witness_output);
1781
1782 }
1783 kassert_panic(
1784 "Thread %p cannot exit while holding sleeplocks\n", td);
1785 }
1786 witness_lock_list_free(lle);
1787}
1788
1789/*
1790 * Warn if any locks other than 'lock' are held. Flags can be passed in to
1791 * exempt Giant and sleepable locks from the checks as well. If any
1792 * non-exempt locks are held, then a supplied message is printed to the
1793 * output channel along with a list of the offending locks. If indicated in the
1794 * flags then a failure results in a panic as well.
1795 */
1796int
1797witness_warn(int flags, struct lock_object *lock, const char *fmt, ...)
1798{
1799 struct lock_list_entry *lock_list, *lle;
1800 struct lock_instance *lock1;
1801 struct thread *td;
1802 va_list ap;
1803 int i, n;
1804
1805 if (witness_cold || witness_watch < 1 || KERNEL_PANICKED())
1806 return (0);
1807 n = 0;
1808 td = curthread;
1809 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next)
1810 for (i = lle->ll_count - 1; i >= 0; i--) {
1811 lock1 = &lle->ll_children[i];
1812 if (lock1->li_lock == lock)
1813 continue;
1814 if (flags & WARN_GIANTOK &&
1815 lock1->li_lock == &Giant.lock_object)
1816 continue;
1817 if (flags & WARN_SLEEPOK &&
1818 (lock1->li_flags & LI_SLEEPABLE) != 0)
1819 continue;
1820 if (n == 0) {
1821 va_start(ap, fmt);
1822 vprintf(fmt, ap);
1823 va_end(ap);
1824 printf(" with the following %slocks held:\n",
1825 (flags & WARN_SLEEPOK) != 0 ?
1826 "non-sleepable " : "");
1827 }
1828 n++;
1829 witness_list_lock(lock1, printf);
1830 }
1831
1832 /*
1833 * Pin the thread in order to avoid problems with thread migration.
1834 * Once that all verifies are passed about spinlocks ownership,
1835 * the thread is in a safe path and it can be unpinned.
1836 */
1837 sched_pin();
1838 lock_list = PCPU_GET(spinlocks);
1839 if (lock_list != NULL && lock_list->ll_count != 0) {
1840 sched_unpin();
1841
1842 /*
1843 * We should only have one spinlock and as long as
1844 * the flags cannot match for this locks class,
1845 * check if the first spinlock is the one curthread
1846 * should hold.
1847 */
1848 lock1 = &lock_list->ll_children[lock_list->ll_count - 1];
1849 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL &&
1850 lock1->li_lock == lock && n == 0)
1851 return (0);
1852
1853 va_start(ap, fmt);
1854 vprintf(fmt, ap);
1855 va_end(ap);
1856 printf(" with the following %slocks held:\n",
1857 (flags & WARN_SLEEPOK) != 0 ? "non-sleepable " : "");
1858 n += witness_list_locks(&lock_list, printf);
1859 } else
1860 sched_unpin();
1861 if (flags & WARN_PANIC && n)
1862 kassert_panic("%s", __func__);
1863 else
1864 witness_debugger(n, __func__);
1865 return (n);
1866}
1867
1868const char *
1869witness_file(struct lock_object *lock)
1870{
1871 struct witness *w;
1872
1873 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
1874 return ("?");
1875 w = lock->lo_witness;
1876 return (w->w_file);
1877}
1878
1879int
1880witness_line(struct lock_object *lock)
1881{
1882 struct witness *w;
1883
1884 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
1885 return (0);
1886 w = lock->lo_witness;
1887 return (w->w_line);
1888}
1889
1890static struct witness *
1891enroll(const char *description, struct lock_class *lock_class)
1892{
1893 struct witness *w;
1894
1895 MPASS(description != NULL);
1896
1897 if (witness_watch == -1 || KERNEL_PANICKED())
1898 return (NULL);
1899 if ((lock_class->lc_flags & LC_SPINLOCK)) {
1900 if (witness_skipspin)
1901 return (NULL);
1902 } else if ((lock_class->lc_flags & LC_SLEEPLOCK) == 0) {
1903 kassert_panic("lock class %s is not sleep or spin",
1904 lock_class->lc_name);
1905 return (NULL);
1906 }
1907
1908 mtx_lock_spin(&w_mtx);
1909 w = witness_hash_get(description);
1910 if (w)
1911 goto found;
1912 if ((w = witness_get()) == NULL)
1913 return (NULL);
1914 MPASS(strlen(description) < MAX_W_NAME);
1915 strcpy(w->w_name, description);
1916 w->w_class = lock_class;
1917 w->w_refcount = 1;
1918 STAILQ_INSERT_HEAD(&w_all, w, w_list);
1919 if (lock_class->lc_flags & LC_SPINLOCK) {
1920 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist);
1921 w_spin_cnt++;
1922 } else if (lock_class->lc_flags & LC_SLEEPLOCK) {
1923 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist);
1924 w_sleep_cnt++;
1925 }
1926
1927 /* Insert new witness into the hash */
1928 witness_hash_put(w);
1929 witness_increment_graph_generation();
1930 mtx_unlock_spin(&w_mtx);
1931 return (w);
1932found:
1933 w->w_refcount++;
1934 if (w->w_refcount == 1)
1935 w->w_class = lock_class;
1936 mtx_unlock_spin(&w_mtx);
1937 if (lock_class != w->w_class)
1938 kassert_panic(
1939 "lock (%s) %s does not match earlier (%s) lock",
1940 description, lock_class->lc_name,
1941 w->w_class->lc_name);
1942 return (w);
1943}
1944
1945static void
1946depart(struct witness *w)
1947{
1948
1949 MPASS(w->w_refcount == 0);
1950 if (w->w_class->lc_flags & LC_SLEEPLOCK) {
1951 w_sleep_cnt--;
1952 } else {
1953 w_spin_cnt--;
1954 }
1955 /*
1956 * Set file to NULL as it may point into a loadable module.
1957 */
1958 w->w_file = NULL;
1959 w->w_line = 0;
1960 witness_increment_graph_generation();
1961}
1962
1963static void
1964adopt(struct witness *parent, struct witness *child)
1965{
1966 int pi, ci, i, j;
1967
1968 if (witness_cold == 0)
1969 mtx_assert(&w_mtx, MA_OWNED);
1970
1971 /* If the relationship is already known, there's no work to be done. */
1972 if (isitmychild(parent, child))
1973 return;
1974
1975 /* When the structure of the graph changes, bump up the generation. */
1976 witness_increment_graph_generation();
1977
1978 /*
1979 * The hard part ... create the direct relationship, then propagate all
1980 * indirect relationships.
1981 */
1982 pi = parent->w_index;
1983 ci = child->w_index;
1984 WITNESS_INDEX_ASSERT(pi);
1985 WITNESS_INDEX_ASSERT(ci);
1986 MPASS(pi != ci);
1987 w_rmatrix[pi][ci] |= WITNESS_PARENT;
1988 w_rmatrix[ci][pi] |= WITNESS_CHILD;
1989
1990 /*
1991 * If parent was not already an ancestor of child,
1992 * then we increment the descendant and ancestor counters.
1993 */
1994 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) {
1995 parent->w_num_descendants++;
1996 child->w_num_ancestors++;
1997 }
1998
1999 /*
2000 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as
2001 * an ancestor of 'pi' during this loop.
2002 */
2003 for (i = 1; i <= w_max_used_index; i++) {
2004 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 &&
2005 (i != pi))
2006 continue;
2007
2008 /* Find each descendant of 'i' and mark it as a descendant. */
2009 for (j = 1; j <= w_max_used_index; j++) {
2010 /*
2011 * Skip children that are already marked as
2012 * descendants of 'i'.
2013 */
2014 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK)
2015 continue;
2016
2017 /*
2018 * We are only interested in descendants of 'ci'. Note
2019 * that 'ci' itself is counted as a descendant of 'ci'.
2020 */
2021 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 &&
2022 (j != ci))
2023 continue;
2024 w_rmatrix[i][j] |= WITNESS_ANCESTOR;
2025 w_rmatrix[j][i] |= WITNESS_DESCENDANT;
2026 w_data[i].w_num_descendants++;
2027 w_data[j].w_num_ancestors++;
2028
2029 /*
2030 * Make sure we aren't marking a node as both an
2031 * ancestor and descendant. We should have caught
2032 * this as a lock order reversal earlier.
2033 */
2034 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) &&
2035 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) {
2036 printf("witness rmatrix paradox! [%d][%d]=%d "
2037 "both ancestor and descendant\n",
2038 i, j, w_rmatrix[i][j]);
2039 kdb_backtrace();
2040 printf("Witness disabled.\n");
2041 witness_watch = -1;
2042 }
2043 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) &&
2044 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) {
2045 printf("witness rmatrix paradox! [%d][%d]=%d "
2046 "both ancestor and descendant\n",
2047 j, i, w_rmatrix[j][i]);
2048 kdb_backtrace();
2049 printf("Witness disabled.\n");
2050 witness_watch = -1;
2051 }
2052 }
2053 }
2054}
2055
2056static void
2057itismychild(struct witness *parent, struct witness *child)
2058{
2059 int unlocked;
2060
2061 MPASS(child != NULL && parent != NULL);
2062 if (witness_cold == 0)
2063 mtx_assert(&w_mtx, MA_OWNED);
2064
2065 if (!witness_lock_type_equal(parent, child)) {
2066 if (witness_cold == 0) {
2067 unlocked = 1;
2068 mtx_unlock_spin(&w_mtx);
2069 } else {
2070 unlocked = 0;
2071 }
2072 kassert_panic(
2073 "%s: parent \"%s\" (%s) and child \"%s\" (%s) are not "
2074 "the same lock type", __func__, parent->w_name,
2075 parent->w_class->lc_name, child->w_name,
2076 child->w_class->lc_name);
2077 if (unlocked)
2078 mtx_lock_spin(&w_mtx);
2079 }
2080 adopt(parent, child);
2081}
2082
2083/*
2084 * Generic code for the isitmy*() functions. The rmask parameter is the
2085 * expected relationship of w1 to w2.
2086 */
2087static int
2088_isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname)
2089{
2090 unsigned char r1, r2;
2091 int i1, i2;
2092
2093 i1 = w1->w_index;
2094 i2 = w2->w_index;
2095 WITNESS_INDEX_ASSERT(i1);
2096 WITNESS_INDEX_ASSERT(i2);
2097 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK;
2098 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK;
2099
2100 /* The flags on one better be the inverse of the flags on the other */
2101 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) ||
2102 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) {
2103 /* Don't squawk if we're potentially racing with an update. */
2104 if (!mtx_owned(&w_mtx))
2105 return (0);
2106 printf("%s: rmatrix mismatch between %s (index %d) and %s "
2107 "(index %d): w_rmatrix[%d][%d] == %hhx but "
2108 "w_rmatrix[%d][%d] == %hhx\n",
2109 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1,
2110 i2, i1, r2);
2111 kdb_backtrace();
2112 printf("Witness disabled.\n");
2113 witness_watch = -1;
2114 }
2115 return (r1 & rmask);
2116}
2117
2118/*
2119 * Checks if @child is a direct child of @parent.
2120 */
2121static int
2122isitmychild(struct witness *parent, struct witness *child)
2123{
2124
2125 return (_isitmyx(parent, child, WITNESS_PARENT, __func__));
2126}
2127
2128/*
2129 * Checks if @descendant is a direct or inderect descendant of @ancestor.
2130 */
2131static int
2132isitmydescendant(struct witness *ancestor, struct witness *descendant)
2133{
2134
2135 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK,
2136 __func__));
2137}
2138
2139static int
2140blessed(struct witness *w1, struct witness *w2)
2141{
2142 int i;
2143 struct witness_blessed *b;
2144
2145 for (i = 0; i < nitems(blessed_list); i++) {
2146 b = &blessed_list[i];
2147 if (strcmp(w1->w_name, b->b_lock1) == 0) {
2148 if (strcmp(w2->w_name, b->b_lock2) == 0)
2149 return (1);
2150 continue;
2151 }
2152 if (strcmp(w1->w_name, b->b_lock2) == 0)
2153 if (strcmp(w2->w_name, b->b_lock1) == 0)
2154 return (1);
2155 }
2156 return (0);
2157}
2158
2159static struct witness *
2160witness_get(void)
2161{
2162 struct witness *w;
2163 int index;
2164
2165 if (witness_cold == 0)
2166 mtx_assert(&w_mtx, MA_OWNED);
2167
2168 if (witness_watch == -1) {
2169 mtx_unlock_spin(&w_mtx);
2170 return (NULL);
2171 }
2172 if (STAILQ_EMPTY(&w_free)) {
2173 witness_watch = -1;
2174 mtx_unlock_spin(&w_mtx);
2175 printf("WITNESS: unable to allocate a new witness object\n");
2176 return (NULL);
2177 }
2178 w = STAILQ_FIRST(&w_free);
2179 STAILQ_REMOVE_HEAD(&w_free, w_list);
2180 w_free_cnt--;
2181 index = w->w_index;
2182 MPASS(index > 0 && index == w_max_used_index+1 &&
2183 index < witness_count);
2184 bzero(w, sizeof(*w));
2185 w->w_index = index;
2186 if (index > w_max_used_index)
2187 w_max_used_index = index;
2188 return (w);
2189}
2190
2191static void
2192witness_free(struct witness *w)
2193{
2194
2195 STAILQ_INSERT_HEAD(&w_free, w, w_list);
2196 w_free_cnt++;
2197}
2198
2199static struct lock_list_entry *
2200witness_lock_list_get(void)
2201{
2202 struct lock_list_entry *lle;
2203
2204 if (witness_watch == -1)
2205 return (NULL);
2206 mtx_lock_spin(&w_mtx);
2207 lle = w_lock_list_free;
2208 if (lle == NULL) {
2209 witness_watch = -1;
2210 mtx_unlock_spin(&w_mtx);
2211 printf("%s: witness exhausted\n", __func__);
2212 return (NULL);
2213 }
2214 w_lock_list_free = lle->ll_next;
2215 mtx_unlock_spin(&w_mtx);
2216 bzero(lle, sizeof(*lle));
2217 return (lle);
2218}
2219
2220static void
2221witness_lock_list_free(struct lock_list_entry *lle)
2222{
2223
2224 mtx_lock_spin(&w_mtx);
2225 lle->ll_next = w_lock_list_free;
2226 w_lock_list_free = lle;
2227 mtx_unlock_spin(&w_mtx);
2228}
2229
2230static struct lock_instance *
2231find_instance(struct lock_list_entry *list, const struct lock_object *lock)
2232{
2233 struct lock_list_entry *lle;
2234 struct lock_instance *instance;
2235 int i;
2236
2237 for (lle = list; lle != NULL; lle = lle->ll_next)
2238 for (i = lle->ll_count - 1; i >= 0; i--) {
2239 instance = &lle->ll_children[i];
2240 if (instance->li_lock == lock)
2241 return (instance);
2242 }
2243 return (NULL);
2244}
2245
2246static void
2247witness_list_lock(struct lock_instance *instance,
2248 int (*prnt)(const char *fmt, ...))
2249{
2250 struct lock_object *lock;
2251
2252 lock = instance->li_lock;
2253 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ?
2254 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name);
2255 if (lock->lo_witness->w_name != lock->lo_name)
2256 prnt(" (%s)", lock->lo_witness->w_name);
2257 prnt(" r = %d (%p) locked @ %s:%d\n",
2258 instance->li_flags & LI_RECURSEMASK, lock,
2259 fixup_filename(instance->li_file), instance->li_line);
2260}
2261
2262static int
2263witness_output(const char *fmt, ...)
2264{
2265 va_list ap;
2266 int ret;
2267
2268 va_start(ap, fmt);
2269 ret = witness_voutput(fmt, ap);
2270 va_end(ap);
2271 return (ret);
2272}
2273
2274static int
2275witness_voutput(const char *fmt, va_list ap)
2276{
2277 int ret;
2278
2279 ret = 0;
2280 switch (witness_channel) {
2281 case WITNESS_CONSOLE:
2282 ret = vprintf(fmt, ap);
2283 break;
2284 case WITNESS_LOG:
2285 vlog(LOG_NOTICE, fmt, ap);
2286 break;
2287 case WITNESS_NONE:
2288 break;
2289 }
2290 return (ret);
2291}
2292
2293#ifdef DDB
2294static int
2295witness_thread_has_locks(struct thread *td)
2296{
2297
2298 if (td->td_sleeplocks == NULL)
2299 return (0);
2300 return (td->td_sleeplocks->ll_count != 0);
2301}
2302
2303static int
2304witness_proc_has_locks(struct proc *p)
2305{
2306 struct thread *td;
2307
2308 FOREACH_THREAD_IN_PROC(p, td) {
2309 if (witness_thread_has_locks(td))
2310 return (1);
2311 }
2312 return (0);
2313}
2314#endif
2315
2316int
2317witness_list_locks(struct lock_list_entry **lock_list,
2318 int (*prnt)(const char *fmt, ...))
2319{
2320 struct lock_list_entry *lle;
2321 int i, nheld;
2322
2323 nheld = 0;
2324 for (lle = *lock_list; lle != NULL; lle = lle->ll_next)
2325 for (i = lle->ll_count - 1; i >= 0; i--) {
2326 witness_list_lock(&lle->ll_children[i], prnt);
2327 nheld++;
2328 }
2329 return (nheld);
2330}
2331
2332/*
2333 * This is a bit risky at best. We call this function when we have timed
2334 * out acquiring a spin lock, and we assume that the other CPU is stuck
2335 * with this lock held. So, we go groveling around in the other CPU's
2336 * per-cpu data to try to find the lock instance for this spin lock to
2337 * see when it was last acquired.
2338 */
2339void
2340witness_display_spinlock(struct lock_object *lock, struct thread *owner,
2341 int (*prnt)(const char *fmt, ...))
2342{
2343 struct lock_instance *instance;
2344 struct pcpu *pc;
2345
2346 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU)
2347 return;
2348 pc = pcpu_find(owner->td_oncpu);
2349 instance = find_instance(pc->pc_spinlocks, lock);
2350 if (instance != NULL)
2351 witness_list_lock(instance, prnt);
2352}
2353
2354void
2355witness_save(struct lock_object *lock, const char **filep, int *linep)
2356{
2357 struct lock_list_entry *lock_list;
2358 struct lock_instance *instance;
2359 struct lock_class *class;
2360
2361 /*
2362 * This function is used independently in locking code to deal with
2363 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant
2364 * is gone.
2365 */
2366 if (SCHEDULER_STOPPED())
2367 return;
2368 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2369 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED())
2370 return;
2371 class = LOCK_CLASS(lock);
2372 if (class->lc_flags & LC_SLEEPLOCK)
2373 lock_list = curthread->td_sleeplocks;
2374 else {
2375 if (witness_skipspin)
2376 return;
2377 lock_list = PCPU_GET(spinlocks);
2378 }
2379 instance = find_instance(lock_list, lock);
2380 if (instance == NULL) {
2381 kassert_panic("%s: lock (%s) %s not locked", __func__,
2382 class->lc_name, lock->lo_name);
2383 return;
2384 }
2385 *filep = instance->li_file;
2386 *linep = instance->li_line;
2387}
2388
2389void
2390witness_restore(struct lock_object *lock, const char *file, int line)
2391{
2392 struct lock_list_entry *lock_list;
2393 struct lock_instance *instance;
2394 struct lock_class *class;
2395
2396 /*
2397 * This function is used independently in locking code to deal with
2398 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant
2399 * is gone.
2400 */
2401 if (SCHEDULER_STOPPED())
2402 return;
2403 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2404 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED())
2405 return;
2406 class = LOCK_CLASS(lock);
2407 if (class->lc_flags & LC_SLEEPLOCK)
2408 lock_list = curthread->td_sleeplocks;
2409 else {
2410 if (witness_skipspin)
2411 return;
2412 lock_list = PCPU_GET(spinlocks);
2413 }
2414 instance = find_instance(lock_list, lock);
2415 if (instance == NULL)
2416 kassert_panic("%s: lock (%s) %s not locked", __func__,
2417 class->lc_name, lock->lo_name);
2418 lock->lo_witness->w_file = file;
2419 lock->lo_witness->w_line = line;
2420 if (instance == NULL)
2421 return;
2422 instance->li_file = file;
2423 instance->li_line = line;
2424}
2425
2426void
2427witness_assert(const struct lock_object *lock, int flags, const char *file,
2428 int line)
2429{
2430#ifdef INVARIANT_SUPPORT
2431 struct lock_instance *instance;
2432 struct lock_class *class;
2433
2434 if (lock->lo_witness == NULL || witness_watch < 1 || KERNEL_PANICKED())
2435 return;
2436 class = LOCK_CLASS(lock);
2437 if ((class->lc_flags & LC_SLEEPLOCK) != 0)
2438 instance = find_instance(curthread->td_sleeplocks, lock);
2439 else if ((class->lc_flags & LC_SPINLOCK) != 0)
2440 instance = find_instance(PCPU_GET(spinlocks), lock);
2441 else {
2442 kassert_panic("Lock (%s) %s is not sleep or spin!",
2443 class->lc_name, lock->lo_name);
2444 return;
2445 }
2446 switch (flags) {
2447 case LA_UNLOCKED:
2448 if (instance != NULL)
2449 kassert_panic("Lock (%s) %s locked @ %s:%d.",
2450 class->lc_name, lock->lo_name,
2451 fixup_filename(file), line);
2452 break;
2453 case LA_LOCKED:
2454 case LA_LOCKED | LA_RECURSED:
2455 case LA_LOCKED | LA_NOTRECURSED:
2456 case LA_SLOCKED:
2457 case LA_SLOCKED | LA_RECURSED:
2458 case LA_SLOCKED | LA_NOTRECURSED:
2459 case LA_XLOCKED:
2460 case LA_XLOCKED | LA_RECURSED:
2461 case LA_XLOCKED | LA_NOTRECURSED:
2462 if (instance == NULL) {
2463 kassert_panic("Lock (%s) %s not locked @ %s:%d.",
2464 class->lc_name, lock->lo_name,
2465 fixup_filename(file), line);
2466 break;
2467 }
2468 if ((flags & LA_XLOCKED) != 0 &&
2469 (instance->li_flags & LI_EXCLUSIVE) == 0)
2470 kassert_panic(
2471 "Lock (%s) %s not exclusively locked @ %s:%d.",
2472 class->lc_name, lock->lo_name,
2473 fixup_filename(file), line);
2474 if ((flags & LA_SLOCKED) != 0 &&
2475 (instance->li_flags & LI_EXCLUSIVE) != 0)
2476 kassert_panic(
2477 "Lock (%s) %s exclusively locked @ %s:%d.",
2478 class->lc_name, lock->lo_name,
2479 fixup_filename(file), line);
2480 if ((flags & LA_RECURSED) != 0 &&
2481 (instance->li_flags & LI_RECURSEMASK) == 0)
2482 kassert_panic("Lock (%s) %s not recursed @ %s:%d.",
2483 class->lc_name, lock->lo_name,
2484 fixup_filename(file), line);
2485 if ((flags & LA_NOTRECURSED) != 0 &&
2486 (instance->li_flags & LI_RECURSEMASK) != 0)
2487 kassert_panic("Lock (%s) %s recursed @ %s:%d.",
2488 class->lc_name, lock->lo_name,
2489 fixup_filename(file), line);
2490 break;
2491 default:
2492 kassert_panic("Invalid lock assertion at %s:%d.",
2493 fixup_filename(file), line);
2494 }
2495#endif /* INVARIANT_SUPPORT */
2496}
2497
2498static void
2499witness_setflag(struct lock_object *lock, int flag, int set)
2500{
2501 struct lock_list_entry *lock_list;
2502 struct lock_instance *instance;
2503 struct lock_class *class;
2504
2505 if (lock->lo_witness == NULL || witness_watch == -1 || KERNEL_PANICKED())
2506 return;
2507 class = LOCK_CLASS(lock);
2508 if (class->lc_flags & LC_SLEEPLOCK)
2509 lock_list = curthread->td_sleeplocks;
2510 else {
2511 if (witness_skipspin)
2512 return;
2513 lock_list = PCPU_GET(spinlocks);
2514 }
2515 instance = find_instance(lock_list, lock);
2516 if (instance == NULL) {
2517 kassert_panic("%s: lock (%s) %s not locked", __func__,
2518 class->lc_name, lock->lo_name);
2519 return;
2520 }
2521
2522 if (set)
2523 instance->li_flags |= flag;
2524 else
2525 instance->li_flags &= ~flag;
2526}
2527
2528void
2529witness_norelease(struct lock_object *lock)
2530{
2531
2532 witness_setflag(lock, LI_NORELEASE, 1);
2533}
2534
2535void
2536witness_releaseok(struct lock_object *lock)
2537{
2538
2539 witness_setflag(lock, LI_NORELEASE, 0);
2540}
2541
2542#ifdef DDB
2543static void
2544witness_ddb_list(struct thread *td)
2545{
2546
2547 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2548 KASSERT(kdb_active, ("%s: not in the debugger", __func__));
2549
2550 if (witness_watch < 1)
2551 return;
2552
2553 witness_list_locks(&td->td_sleeplocks, db_printf);
2554
2555 /*
2556 * We only handle spinlocks if td == curthread. This is somewhat broken
2557 * if td is currently executing on some other CPU and holds spin locks
2558 * as we won't display those locks. If we had a MI way of getting
2559 * the per-cpu data for a given cpu then we could use
2560 * td->td_oncpu to get the list of spinlocks for this thread
2561 * and "fix" this.
2562 *
2563 * That still wouldn't really fix this unless we locked the scheduler
2564 * lock or stopped the other CPU to make sure it wasn't changing the
2565 * list out from under us. It is probably best to just not try to
2566 * handle threads on other CPU's for now.
2567 */
2568 if (td == curthread && PCPU_GET(spinlocks) != NULL)
2569 witness_list_locks(PCPU_PTR(spinlocks), db_printf);
2570}
2571
2572DB_SHOW_COMMAND(locks, db_witness_list)
2573{
2574 struct thread *td;
2575
2576 if (have_addr)
2577 td = db_lookup_thread(addr, true);
2578 else
2579 td = kdb_thread;
2580 witness_ddb_list(td);
2581}
2582
2583DB_SHOW_ALL_COMMAND(locks, db_witness_list_all)
2584{
2585 struct thread *td;
2586 struct proc *p;
2587
2588 /*
2589 * It would be nice to list only threads and processes that actually
2590 * held sleep locks, but that information is currently not exported
2591 * by WITNESS.
2592 */
2593 FOREACH_PROC_IN_SYSTEM(p) {
2594 if (!witness_proc_has_locks(p))
2595 continue;
2596 FOREACH_THREAD_IN_PROC(p, td) {
2597 if (!witness_thread_has_locks(td))
2598 continue;
2599 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid,
2600 p->p_comm, td, td->td_tid);
2601 witness_ddb_list(td);
2602 if (db_pager_quit)
2603 return;
2604 }
2605 }
2606}
2607DB_SHOW_ALIAS(alllocks, db_witness_list_all)
2608
2609DB_SHOW_COMMAND(witness, db_witness_display)
2610{
2611
2612 witness_ddb_display(db_printf);
2613}
2614#endif
2615
2616static void
2617sbuf_print_witness_badstacks(struct sbuf *sb, size_t *oldidx)
2618{
2619 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2;
2620 struct witness *tmp_w1, *tmp_w2, *w1, *w2;
2621 int generation, i, j;
2622
2623 tmp_data1 = NULL;
2624 tmp_data2 = NULL;
2625 tmp_w1 = NULL;
2626 tmp_w2 = NULL;
2627
2628 /* Allocate and init temporary storage space. */
2629 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
2630 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
2631 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP,
2632 M_WAITOK | M_ZERO);
2633 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP,
2634 M_WAITOK | M_ZERO);
2635 stack_zero(&tmp_data1->wlod_stack);
2636 stack_zero(&tmp_data2->wlod_stack);
2637
2638restart:
2639 mtx_lock_spin(&w_mtx);
2640 generation = w_generation;
2641 mtx_unlock_spin(&w_mtx);
2642 sbuf_printf(sb, "Number of known direct relationships is %d\n",
2643 w_lohash.wloh_count);
2644 for (i = 1; i < w_max_used_index; i++) {
2645 mtx_lock_spin(&w_mtx);
2646 if (generation != w_generation) {
2647 mtx_unlock_spin(&w_mtx);
2648
2649 /* The graph has changed, try again. */
2650 *oldidx = 0;
2651 sbuf_clear(sb);
2652 goto restart;
2653 }
2654
2655 w1 = &w_data[i];
2656 if (w1->w_reversed == 0) {
2657 mtx_unlock_spin(&w_mtx);
2658 continue;
2659 }
2660
2661 /* Copy w1 locally so we can release the spin lock. */
2662 *tmp_w1 = *w1;
2663 mtx_unlock_spin(&w_mtx);
2664
2665 if (tmp_w1->w_reversed == 0)
2666 continue;
2667 for (j = 1; j < w_max_used_index; j++) {
2668 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j)
2669 continue;
2670
2671 mtx_lock_spin(&w_mtx);
2672 if (generation != w_generation) {
2673 mtx_unlock_spin(&w_mtx);
2674
2675 /* The graph has changed, try again. */
2676 *oldidx = 0;
2677 sbuf_clear(sb);
2678 goto restart;
2679 }
2680
2681 w2 = &w_data[j];
2682 data1 = witness_lock_order_get(w1, w2);
2683 data2 = witness_lock_order_get(w2, w1);
2684
2685 /*
2686 * Copy information locally so we can release the
2687 * spin lock.
2688 */
2689 *tmp_w2 = *w2;
2690
2691 if (data1) {
2692 stack_zero(&tmp_data1->wlod_stack);
2693 stack_copy(&data1->wlod_stack,
2694 &tmp_data1->wlod_stack);
2695 }
2696 if (data2 && data2 != data1) {
2697 stack_zero(&tmp_data2->wlod_stack);
2698 stack_copy(&data2->wlod_stack,
2699 &tmp_data2->wlod_stack);
2700 }
2701 mtx_unlock_spin(&w_mtx);
2702
2703 if (blessed(tmp_w1, tmp_w2))
2704 continue;
2705
2706 sbuf_printf(sb,
2707 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n",
2708 tmp_w1->w_name, tmp_w1->w_class->lc_name,
2709 tmp_w2->w_name, tmp_w2->w_class->lc_name);
2710 if (data1) {
2711 sbuf_printf(sb,
2712 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
2713 tmp_w1->w_name, tmp_w1->w_class->lc_name,
2714 tmp_w2->w_name, tmp_w2->w_class->lc_name);
2715 stack_sbuf_print(sb, &tmp_data1->wlod_stack);
2716 sbuf_printf(sb, "\n");
2717 }
2718 if (data2 && data2 != data1) {
2719 sbuf_printf(sb,
2720 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
2721 tmp_w2->w_name, tmp_w2->w_class->lc_name,
2722 tmp_w1->w_name, tmp_w1->w_class->lc_name);
2723 stack_sbuf_print(sb, &tmp_data2->wlod_stack);
2724 sbuf_printf(sb, "\n");
2725 }
2726 }
2727 }
2728 mtx_lock_spin(&w_mtx);
2729 if (generation != w_generation) {
2730 mtx_unlock_spin(&w_mtx);
2731
2732 /*
2733 * The graph changed while we were printing stack data,
2734 * try again.
2735 */
2736 *oldidx = 0;
2737 sbuf_clear(sb);
2738 goto restart;
2739 }
2740 mtx_unlock_spin(&w_mtx);
2741
2742 /* Free temporary storage space. */
2743 free(tmp_data1, M_TEMP);
2744 free(tmp_data2, M_TEMP);
2745 free(tmp_w1, M_TEMP);
2746 free(tmp_w2, M_TEMP);
2747}
2748
2749static int
2750sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS)
2751{
2752 struct sbuf *sb;
2753 int error;
2754
2755 if (witness_watch < 1) {
2756 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
2757 return (error);
2758 }
2759 if (witness_cold) {
2760 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
2761 return (error);
2762 }
2763 error = 0;
2764 sb = sbuf_new(NULL, NULL, badstack_sbuf_size, SBUF_AUTOEXTEND);
2765 if (sb == NULL)
2766 return (ENOMEM);
2767
2768 sbuf_print_witness_badstacks(sb, &req->oldidx);
2769
2770 sbuf_finish(sb);
2771 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
2772 sbuf_delete(sb);
2773
2774 return (error);
2775}
2776
2777#ifdef DDB
2778static int
2779sbuf_db_printf_drain(void *arg __unused, const char *data, int len)
2780{
2781
2782 return (db_printf("%.*s", len, data));
2783}
2784
2785DB_SHOW_COMMAND(badstacks, db_witness_badstacks)
2786{
2787 struct sbuf sb;
2788 char buffer[128];
2789 size_t dummy;
2790
2791 sbuf_new(&sb, buffer, sizeof(buffer), SBUF_FIXEDLEN);
2792 sbuf_set_drain(&sb, sbuf_db_printf_drain, NULL);
2793 sbuf_print_witness_badstacks(&sb, &dummy);
2794 sbuf_finish(&sb);
2795}
2796#endif
2797
2798static int
2799sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS)
2800{
2801 static const struct {
2802 enum witness_channel channel;
2803 const char *name;
2804 } channels[] = {
2805 { WITNESS_CONSOLE, "console" },
2806 { WITNESS_LOG, "log" },
2807 { WITNESS_NONE, "none" },
2808 };
2809 char buf[16];
2810 u_int i;
2811 int error;
2812
2813 buf[0] = '\0';
2814 for (i = 0; i < nitems(channels); i++)
2815 if (witness_channel == channels[i].channel) {
2816 snprintf(buf, sizeof(buf), "%s", channels[i].name);
2817 break;
2818 }
2819
2820 error = sysctl_handle_string(oidp, buf, sizeof(buf), req);
2821 if (error != 0 || req->newptr == NULL)
2822 return (error);
2823
2824 error = EINVAL;
2825 for (i = 0; i < nitems(channels); i++)
2826 if (strcmp(channels[i].name, buf) == 0) {
2827 witness_channel = channels[i].channel;
2828 error = 0;
2829 break;
2830 }
2831 return (error);
2832}
2833
2834static int
2835sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS)
2836{
2837 struct witness *w;
2838 struct sbuf *sb;
2839 int error;
2840
2841#ifdef __i386__
2842 error = SYSCTL_OUT(req, w_notallowed, sizeof(w_notallowed));
2843 return (error);
2844#endif
2845
2846 if (witness_watch < 1) {
2847 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
2848 return (error);
2849 }
2850 if (witness_cold) {
2851 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
2852 return (error);
2853 }
2854 error = 0;
2855
2856 error = sysctl_wire_old_buffer(req, 0);
2857 if (error != 0)
2858 return (error);
2859 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req);
2860 if (sb == NULL)
2861 return (ENOMEM);
2862 sbuf_printf(sb, "\n");
2863
2864 mtx_lock_spin(&w_mtx);
2865 STAILQ_FOREACH(w, &w_all, w_list)
2866 w->w_displayed = 0;
2867 STAILQ_FOREACH(w, &w_all, w_list)
2868 witness_add_fullgraph(sb, w);
2869 mtx_unlock_spin(&w_mtx);
2870
2871 /*
2872 * Close the sbuf and return to userland.
2873 */
2874 error = sbuf_finish(sb);
2875 sbuf_delete(sb);
2876
2877 return (error);
2878}
2879
2880static int
2881sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS)
2882{
2883 int error, value;
2884
2885 value = witness_watch;
2886 error = sysctl_handle_int(oidp, &value, 0, req);
2887 if (error != 0 || req->newptr == NULL)
2888 return (error);
2889 if (value > 1 || value < -1 ||
2890 (witness_watch == -1 && value != witness_watch))
2891 return (EINVAL);
2892 witness_watch = value;
2893 return (0);
2894}
2895
2896static void
2897witness_add_fullgraph(struct sbuf *sb, struct witness *w)
2898{
2899 int i;
2900
2901 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0))
2902 return;
2903 w->w_displayed = 1;
2904
2905 WITNESS_INDEX_ASSERT(w->w_index);
2906 for (i = 1; i <= w_max_used_index; i++) {
2907 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) {
2908 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name,
2909 w_data[i].w_name);
2910 witness_add_fullgraph(sb, &w_data[i]);
2911 }
2912 }
2913}
2914
2915/*
2916 * A simple hash function. Takes a key pointer and a key size. If size == 0,
2917 * interprets the key as a string and reads until the null
2918 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit
2919 * hash value computed from the key.
2920 */
2921static uint32_t
2922witness_hash_djb2(const uint8_t *key, uint32_t size)
2923{
2924 unsigned int hash = 5381;
2925 int i;
2926
2927 /* hash = hash * 33 + key[i] */
2928 if (size)
2929 for (i = 0; i < size; i++)
2930 hash = ((hash << 5) + hash) + (unsigned int)key[i];
2931 else
2932 for (i = 0; key[i] != 0; i++)
2933 hash = ((hash << 5) + hash) + (unsigned int)key[i];
2934
2935 return (hash);
2936}
2937
2938/*
2939 * Initializes the two witness hash tables. Called exactly once from
2940 * witness_initialize().
2941 */
2942static void
2943witness_init_hash_tables(void)
2944{
2945 int i;
2946
2947 MPASS(witness_cold);
2948
2949 /* Initialize the hash tables. */
2950 for (i = 0; i < WITNESS_HASH_SIZE; i++)
2951 w_hash.wh_array[i] = NULL;
2952
2953 w_hash.wh_size = WITNESS_HASH_SIZE;
2954 w_hash.wh_count = 0;
2955
2956 /* Initialize the lock order data hash. */
2957 w_lofree = NULL;
2958 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) {
2959 memset(&w_lodata[i], 0, sizeof(w_lodata[i]));
2960 w_lodata[i].wlod_next = w_lofree;
2961 w_lofree = &w_lodata[i];
2962 }
2963 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE;
2964 w_lohash.wloh_count = 0;
2965 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++)
2966 w_lohash.wloh_array[i] = NULL;
2967}
2968
2969static struct witness *
2970witness_hash_get(const char *key)
2971{
2972 struct witness *w;
2973 uint32_t hash;
2974
2975 MPASS(key != NULL);
2976 if (witness_cold == 0)
2977 mtx_assert(&w_mtx, MA_OWNED);
2978 hash = witness_hash_djb2(key, 0) % w_hash.wh_size;
2979 w = w_hash.wh_array[hash];
2980 while (w != NULL) {
2981 if (strcmp(w->w_name, key) == 0)
2982 goto out;
2983 w = w->w_hash_next;
2984 }
2985
2986out:
2987 return (w);
2988}
2989
2990static void
2991witness_hash_put(struct witness *w)
2992{
2993 uint32_t hash;
2994
2995 MPASS(w != NULL);
2996 MPASS(w->w_name != NULL);
2997 if (witness_cold == 0)
2998 mtx_assert(&w_mtx, MA_OWNED);
2999 KASSERT(witness_hash_get(w->w_name) == NULL,
3000 ("%s: trying to add a hash entry that already exists!", __func__));
3001 KASSERT(w->w_hash_next == NULL,
3002 ("%s: w->w_hash_next != NULL", __func__));
3003
3004 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size;
3005 w->w_hash_next = w_hash.wh_array[hash];
3006 w_hash.wh_array[hash] = w;
3007 w_hash.wh_count++;
3008}
3009
3010static struct witness_lock_order_data *
3011witness_lock_order_get(struct witness *parent, struct witness *child)
3012{
3013 struct witness_lock_order_data *data = NULL;
3014 struct witness_lock_order_key key;
3015 unsigned int hash;
3016
3017 MPASS(parent != NULL && child != NULL);
3018 key.from = parent->w_index;
3019 key.to = child->w_index;
3020 WITNESS_INDEX_ASSERT(key.from);
3021 WITNESS_INDEX_ASSERT(key.to);
3022 if ((w_rmatrix[parent->w_index][child->w_index]
3023 & WITNESS_LOCK_ORDER_KNOWN) == 0)
3024 goto out;
3025
3026 hash = witness_hash_djb2((const char*)&key,
3027 sizeof(key)) % w_lohash.wloh_size;
3028 data = w_lohash.wloh_array[hash];
3029 while (data != NULL) {
3030 if (witness_lock_order_key_equal(&data->wlod_key, &key))
3031 break;
3032 data = data->wlod_next;
3033 }
3034
3035out:
3036 return (data);
3037}
3038
3039/*
3040 * Verify that parent and child have a known relationship, are not the same,
3041 * and child is actually a child of parent. This is done without w_mtx
3042 * to avoid contention in the common case.
3043 */
3044static int
3045witness_lock_order_check(struct witness *parent, struct witness *child)
3046{
3047
3048 if (parent != child &&
3049 w_rmatrix[parent->w_index][child->w_index]
3050 & WITNESS_LOCK_ORDER_KNOWN &&
3051 isitmychild(parent, child))
3052 return (1);
3053
3054 return (0);
3055}
3056
3057static int
3058witness_lock_order_add(struct witness *parent, struct witness *child)
3059{
3060 struct witness_lock_order_data *data = NULL;
3061 struct witness_lock_order_key key;
3062 unsigned int hash;
3063
3064 MPASS(parent != NULL && child != NULL);
3065 key.from = parent->w_index;
3066 key.to = child->w_index;
3067 WITNESS_INDEX_ASSERT(key.from);
3068 WITNESS_INDEX_ASSERT(key.to);
3069 if (w_rmatrix[parent->w_index][child->w_index]
3070 & WITNESS_LOCK_ORDER_KNOWN)
3071 return (1);
3072
3073 hash = witness_hash_djb2((const char*)&key,
3074 sizeof(key)) % w_lohash.wloh_size;
3075 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN;
3076 data = w_lofree;
3077 if (data == NULL)
3078 return (0);
3079 w_lofree = data->wlod_next;
3080 data->wlod_next = w_lohash.wloh_array[hash];
3081 data->wlod_key = key;
3082 w_lohash.wloh_array[hash] = data;
3083 w_lohash.wloh_count++;
3084 stack_zero(&data->wlod_stack);
3085 stack_save(&data->wlod_stack);
3086 return (1);
3087}
3088
3089/* Call this whenever the structure of the witness graph changes. */
3090static void
3091witness_increment_graph_generation(void)
3092{
3093
3094 if (witness_cold == 0)
3095 mtx_assert(&w_mtx, MA_OWNED);
3096 w_generation++;
3097}
3098
3099static int
3100witness_output_drain(void *arg __unused, const char *data, int len)
3101{
3102
3103 witness_output("%.*s", len, data);
3104 return (len);
3105}
3106
3107static void
3108witness_debugger(int cond, const char *msg)
3109{
3110 char buf[32];
3111 struct sbuf sb;
3112 struct stack st;
3113
3114 if (!cond)
3115 return;
3116
3117 if (witness_trace) {
3118 sbuf_new(&sb, buf, sizeof(buf), SBUF_FIXEDLEN);
3119 sbuf_set_drain(&sb, witness_output_drain, NULL);
3120
3121 stack_zero(&st);
3122 stack_save(&st);
3123 witness_output("stack backtrace:\n");
3124 stack_sbuf_print_ddb(&sb, &st);
3125
3126 sbuf_finish(&sb);
3127 }
3128
3129 witness_enter_debugger(msg);
3130}
3131
3132static void
3133witness_enter_debugger(const char *msg)
3134{
3135#ifdef KDB
3136 if (witness_kdb)
3137 kdb_enter(KDB_WHY_WITNESS, msg);
3138#endif
3139}
set
METHOD int set
Definition: cpufreq_if.m:43
type
device_property_type_t type
Definition: bus_if.m:941
parent
device_t parent
Definition: device_if.m:187
name
const char * name
Definition: kern_fail.c:145
st
static struct bt_table st
Definition: kern_boottrace.c:86
malloc
void *() malloc(size_t size, struct malloc_type *mtp, int flags)
Definition: kern_malloc.c:632
free
void free(void *addr, struct malloc_type *mtp)
Definition: kern_malloc.c:907
lock_class_mtx_sleep
struct lock_class lock_class_mtx_sleep
Definition: kern_mutex.c:115
Giant
struct mtx __exclusive_cache_line Giant
Definition: kern_mutex.c:181
lock_class_mtx_spin
struct lock_class lock_class_mtx_spin
Definition: kern_mutex.c:128
lock_class_rm
struct lock_class lock_class_rm
Definition: kern_rmlock.c:88
lock_class_rw
struct lock_class lock_class_rw
Definition: kern_rwlock.c:82
panic
void panic(const char *fmt,...)
Definition: kern_shutdown.c:884
lock_class_sx
struct lock_class lock_class_sx
Definition: kern_sx.c:127
sysctl_wire_old_buffer
int sysctl_wire_old_buffer(struct sysctl_req *req, size_t len)
Definition: kern_sysctl.c:2136
sysctl_handle_int
int sysctl_handle_int(SYSCTL_HANDLER_ARGS)
Definition: kern_sysctl.c:1644
sysctl_handle_string
int sysctl_handle_string(SYSCTL_HANDLER_ARGS)
Definition: kern_sysctl.c:1778
sbuf_new_for_sysctl
struct sbuf * sbuf_new_for_sysctl(struct sbuf *s, char *buf, int length, struct sysctl_req *req)
Definition: kern_sysctl.c:2503
value
caddr_t value
Definition: linker_if.m:63
I
#define I(x, y, z)
Definition: md5c.c:101
child
device_t child
Definition: msi_if.m:58
data
uint32_t * data
Definition: msi_if.m:90
addr
uint64_t * addr
Definition: msi_if.m:89
lock_instance
Definition: subr_witness.c:195
lock_instance::li_file
const char * li_file
Definition: subr_witness.c:197
lock_instance::li_lock
struct lock_object * li_lock
Definition: subr_witness.c:196
lock_instance::li_flags
u_int li_flags
Definition: subr_witness.c:199
lock_instance::li_line
int li_line
Definition: subr_witness.c:198
lock_list_entry
Definition: subr_witness.c:212
lock_list_entry::ll_count
u_int ll_count
Definition: subr_witness.c:215
lock_list_entry::ll_children
struct lock_instance ll_children[LOCK_NCHILDREN]
Definition: subr_witness.c:214
lock_list_entry::ll_next
struct lock_list_entry * ll_next
Definition: subr_witness.c:213
witness_blessed
Definition: subr_witness.c:278
witness_blessed::b_lock1
const char * b_lock1
Definition: subr_witness.c:279
witness_blessed::b_lock2
const char * b_lock2
Definition: subr_witness.c:280
witness_hash
Definition: subr_witness.c:247
witness_hash::wh_size
uint32_t wh_size
Definition: subr_witness.c:249
witness_hash::wh_count
uint32_t wh_count
Definition: subr_witness.c:250
witness_hash::wh_array
struct witness * wh_array[WITNESS_HASH_SIZE]
Definition: subr_witness.c:248
witness_lock_order_data
Definition: subr_witness.c:261
witness_lock_order_data::wlod_key
struct witness_lock_order_key wlod_key
Definition: subr_witness.c:263
witness_lock_order_data::wlod_stack
struct stack wlod_stack
Definition: subr_witness.c:262
witness_lock_order_data::wlod_next
struct witness_lock_order_data * wlod_next
Definition: subr_witness.c:264
witness_lock_order_hash
Definition: subr_witness.c:272
witness_lock_order_hash::wloh_array
struct witness_lock_order_data * wloh_array[WITNESS_LO_HASH_SIZE]
Definition: subr_witness.c:273
witness_lock_order_hash::wloh_size
u_int wloh_size
Definition: subr_witness.c:274
witness_lock_order_hash::wloh_count
u_int wloh_count
Definition: subr_witness.c:275
witness_lock_order_key
Definition: subr_witness.c:256
witness_lock_order_key::from
uint16_t from
Definition: subr_witness.c:257
witness_lock_order_key::to
uint16_t to
Definition: subr_witness.c:258
witness_order_list_entry
Definition: subr_witness.c:288
witness_order_list_entry::w_name
const char * w_name
Definition: subr_witness.c:289
witness_order_list_entry::w_class
struct lock_class * w_class
Definition: subr_witness.c:290
witness_pendhelp
Definition: subr_witness.c:283
witness_pendhelp::wh_type
const char * wh_type
Definition: subr_witness.c:284
witness_pendhelp::wh_lock
struct lock_object * wh_lock
Definition: subr_witness.c:285
witness::w_class
struct lock_class * w_class
Definition: subr_witness.c:225
witness::w_name
char w_name[MAX_W_NAME]
Definition: subr_witness.c:223
witness::w_index
uint32_t w_index
Definition: subr_witness.c:224
kdb_active
u_char __read_frequently kdb_active
Definition: subr_kdb.c:56
kdb_thread
struct thread * kdb_thread
Definition: subr_kdb.c:61
kdb_enter
void kdb_enter(const char *why, const char *msg)
Definition: subr_kdb.c:498
kdb_backtrace
void kdb_backtrace(void)
Definition: subr_kdb.c:429
pcpu_find
struct pcpu * pcpu_find(u_int cpuid)
Definition: subr_pcpu.c:283
printf
int printf(const char *fmt,...)
Definition: subr_prf.c:397
vlog
void vlog(int level, const char *fmt, va_list ap)
Definition: subr_prf.c:324
vprintf
int vprintf(const char *fmt, va_list ap)
Definition: subr_prf.c:410
snprintf
int snprintf(char *str, size_t size, const char *format,...)
Definition: subr_prf.c:550
sbuf_finish
int sbuf_finish(struct sbuf *s)
Definition: subr_sbuf.c:833
sbuf_delete
void sbuf_delete(struct sbuf *s)
Definition: subr_sbuf.c:898
sbuf_printf
int sbuf_printf(struct sbuf *s, const char *fmt,...)
Definition: subr_sbuf.c:739
sbuf_set_drain
void sbuf_set_drain(struct sbuf *s, sbuf_drain_func *func, void *ctx)
Definition: subr_sbuf.c:376
sbuf_len
ssize_t sbuf_len(struct sbuf *s)
Definition: subr_sbuf.c:877
sbuf_data
char * sbuf_data(struct sbuf *s)
Definition: subr_sbuf.c:862
sbuf_clear
void sbuf_clear(struct sbuf *s)
Definition: subr_sbuf.c:316
sbuf_new
struct sbuf * sbuf_new(struct sbuf *s, char *buf, int length, int flags)
Definition: subr_sbuf.c:196
stack_sbuf_print_flags
int stack_sbuf_print_flags(struct sbuf *sb, const struct stack *st, int flags, enum stack_sbuf_fmt format)
Definition: subr_stack.c:173
stack_zero
void stack_zero(struct stack *st)
Definition: subr_stack.c:89
stack_copy
void stack_copy(const struct stack *src, struct stack *dst)
Definition: subr_stack.c:82
stack_sbuf_print
void stack_sbuf_print(struct sbuf *sb, const struct stack *st)
Definition: subr_stack.c:203
flags
uint16_t flags
Definition: subr_stats.c:2
witness_spin_warn
static int witness_spin_warn
Definition: subr_witness.c:753
w_free
static struct witness_list w_free
Definition: subr_witness.c:457
WITNESS_LOCK_ORDER_KNOWN
#define WITNESS_LOCK_ORDER_KNOWN
Definition: subr_witness.c:176
witness_destroy
void witness_destroy(struct lock_object *lock)
Definition: subr_witness.c:917
WITNESS_DESCENDANT
#define WITNESS_DESCENDANT
Definition: subr_witness.c:168
WITNESS_CHILD
#define WITNESS_CHILD
Definition: subr_witness.c:167
witness_lock_order_get
static struct witness_lock_order_data * witness_lock_order_get(struct witness *parent, struct witness *child)
Definition: subr_witness.c:3010
witness_file
const char * witness_file(struct lock_object *lock)
Definition: subr_witness.c:1868
sysctl_debug_witness_channel
static int sysctl_debug_witness_channel(SYSCTL_HANDLER_ARGS)
Definition: subr_witness.c:2798
witness_hash_put
static void witness_hash_put(struct witness *w)
Definition: subr_witness.c:2990
WITNESS_HASH_SIZE
#define WITNESS_HASH_SIZE
Definition: subr_witness.c:139
w_all
static struct witness_list w_all
Definition: subr_witness.c:458
LI_SLEEPABLE
#define LI_SLEEPABLE
Definition: subr_witness.c:134
w_locklistdata
static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]
Definition: subr_witness.c:477
WITNESS_LO_HASH_SIZE
#define WITNESS_LO_HASH_SIZE
Definition: subr_witness.c:146
witness_downgrade
void witness_downgrade(struct lock_object *lock, int flags, const char *file, int line)
Definition: subr_witness.c:1608
WITNESS_REVERSAL
#define WITNESS_REVERSAL
Definition: subr_witness.c:173
LI_NORELEASE
#define LI_NORELEASE
Definition: subr_witness.c:133
WITNESS_ANCESTOR_MASK
#define WITNESS_ANCESTOR_MASK
Definition: subr_witness.c:169
witness_line
int witness_line(struct lock_object *lock)
Definition: subr_witness.c:1879
witness_assert
void witness_assert(const struct lock_object *lock, int flags, const char *file, int line)
Definition: subr_witness.c:2426
FEATURE
FEATURE(witness, "kernel has witness(9) support")
itismychild
static void itismychild(struct witness *parent, struct witness *child)
Definition: subr_witness.c:2056
w_generation
static unsigned int w_generation
Definition: subr_witness.c:485
witness_lock_type_equal
static __inline int witness_lock_type_equal(struct witness *w1, struct witness *w2)
Definition: subr_witness.c:298
WITNESS_LO_DATA_COUNT
#define WITNESS_LO_DATA_COUNT
Definition: subr_witness.c:143
sysctl_debug_witness_fullgraph
static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS)
Definition: subr_witness.c:2834
witness_unlock
void witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
Definition: subr_witness.c:1654
w_data
static struct witness * w_data
Definition: subr_witness.c:475
witness_list_lock
static void witness_list_lock(struct lock_instance *instance, int(*prnt)(const char *fmt,...))
Definition: subr_witness.c:2246
SYSCTL_NODE
static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW|CTLFLAG_MPSAFE, NULL, "Witness Locking")
w_spin
static struct witness_list w_spin
Definition: subr_witness.c:461
witness_startup
void witness_startup(void *mem)
Definition: subr_witness.c:789
witness_restore
void witness_restore(struct lock_object *lock, const char *file, int line)
Definition: subr_witness.c:2389
LOCK_CHILDCOUNT
#define LOCK_CHILDCOUNT
Definition: subr_witness.c:154
w_notrunning
static const char w_notrunning[]
Definition: subr_witness.c:486
WITNESS_RELATED_MASK
#define WITNESS_RELATED_MASK
Definition: subr_witness.c:171
LI_RECURSEMASK
#define LI_RECURSEMASK
Definition: subr_witness.c:131
w_rmatrix
static uint8_t ** w_rmatrix
Definition: subr_witness.c:476
WITNESS_PARENT
#define WITNESS_PARENT
Definition: subr_witness.c:165
KTR_WITNESS
#define KTR_WITNESS
Definition: subr_witness.c:128
sbuf_print_witness_badstacks
static void sbuf_print_witness_badstacks(struct sbuf *sb, size_t *oldidx)
Definition: subr_witness.c:2616
w_max_used_index
static int w_max_used_index
Definition: subr_witness.c:484
WITNESS_PENDLIST
#define WITNESS_PENDLIST
Definition: subr_witness.c:140
witness_defineorder
int witness_defineorder(struct lock_object *lock1, struct lock_object *lock2)
Definition: subr_witness.c:1076
sysctl_debug_witness_watch
static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS)
Definition: subr_witness.c:2880
witness_watch
static int witness_watch
Definition: subr_witness.c:378
witness_lock
void witness_lock(struct lock_object *lock, int flags, const char *file, int line)
Definition: subr_witness.c:1503
isitmychild
static int isitmychild(struct witness *parent, struct witness *child)
Definition: subr_witness.c:2121
witness_output_drain
static int static int witness_output_drain(void *arg __unused, const char *data, int len)
Definition: subr_witness.c:3099
SYSCTL_PROC
SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RWTUN|CTLTYPE_INT|CTLFLAG_MPSAFE, NULL, 0, sysctl_debug_witness_watch, "I", "witness is watching lock operations")
adopt
static void adopt(struct witness *parent, struct witness *child)
Definition: subr_witness.c:1963
WITNESS_DTOA
#define WITNESS_DTOA(x)
Definition: subr_witness.c:179
witness_skipspin
int witness_skipspin
Definition: subr_witness.c:413
w_stillcold
static const char w_stillcold[]
Definition: subr_witness.c:487
witness_warn
int witness_warn(int flags, struct lock_object *lock, const char *fmt,...)
Definition: subr_witness.c:1796
fixup_filename
static const char * fixup_filename(const char *file)
Definition: subr_witness.c:757
w_lock_list_free
static struct lock_list_entry * w_lock_list_free
Definition: subr_witness.c:465
w_lohash
static struct witness_lock_order_hash w_lohash
Definition: subr_witness.c:483
witness_releaseok
void witness_releaseok(struct lock_object *lock)
Definition: subr_witness.c:2535
FULLGRAPH_SBUF_SIZE
#define FULLGRAPH_SBUF_SIZE
Definition: subr_witness.c:158
WITNESS_ANCESTOR
#define WITNESS_ANCESTOR
Definition: subr_witness.c:166
SYSCTL_INT
SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, "")
witness_init
void witness_init(struct lock_object *lock, const char *type)
Definition: subr_witness.c:876
w_free_cnt
static int w_free_cnt
Definition: subr_witness.c:469
witness_get
static struct witness * witness_get(void)
Definition: subr_witness.c:2159
__FBSDID
__FBSDID("$FreeBSD$")
badstack_sbuf_size
int badstack_sbuf_size
Definition: subr_witness.c:417
w_mtx
static struct mtx w_mtx
Definition: subr_witness.c:454
LI_EXCLUSIVE
#define LI_EXCLUSIVE
Definition: subr_witness.c:132
enroll
static struct witness * enroll(const char *description, struct lock_class *lock_class)
Definition: subr_witness.c:1890
w_sleep_cnt
static int w_sleep_cnt
Definition: subr_witness.c:469
witness_init_hash_tables
static void witness_init_hash_tables(void)
Definition: subr_witness.c:2942
witness_free
static void witness_free(struct witness *m)
Definition: subr_witness.c:2191
depart
static void depart(struct witness *w)
Definition: subr_witness.c:1945
witness_lock_order_key_equal
static __inline int witness_lock_order_key_equal(const struct witness_lock_order_key *a, const struct witness_lock_order_key *b)
Definition: subr_witness.c:306
witness_lock_list_get
static struct lock_list_entry * witness_lock_list_get(void)
Definition: subr_witness.c:2199
witness_add_fullgraph
static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent)
Definition: subr_witness.c:2896
witness_debugger
static void witness_debugger(int cond, const char *msg)
Definition: subr_witness.c:3107
w_sleep
static struct witness_list w_sleep
Definition: subr_witness.c:462
witness_lock_order_check
static int witness_lock_order_check(struct witness *parent, struct witness *child)
Definition: subr_witness.c:3044
w_spin_cnt
static int w_spin_cnt
Definition: subr_witness.c:469
witness_lock_list_free
static void witness_lock_list_free(struct lock_list_entry *lle)
Definition: subr_witness.c:2220
witness_increment_graph_generation
static void witness_increment_graph_generation(void)
Definition: subr_witness.c:3090
WITNESS_DESCENDANT_MASK
#define WITNESS_DESCENDANT_MASK
Definition: subr_witness.c:170
witness_upgrade
void witness_upgrade(struct lock_object *lock, int flags, const char *file, int line)
Definition: subr_witness.c:1563
w_lofree
static struct witness_lock_order_data * w_lofree
Definition: subr_witness.c:482
witness_checkorder
void witness_checkorder(struct lock_object *lock, int flags, const char *file, int line, struct lock_object *interlock)
Definition: subr_witness.c:1109
MALLOC_DEFINE
static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness")
pending_locks
static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]
Definition: subr_witness.c:466
_isitmyx
static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname)
Definition: subr_witness.c:2087
LOCK_NCHILDREN
#define LOCK_NCHILDREN
Definition: subr_witness.c:153
witness_count
int witness_count
Definition: subr_witness.c:419
WITNESS_COUNT
#define WITNESS_COUNT
Definition: subr_witness.c:137
sysctl_debug_witness_badstacks
static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS)
Definition: subr_witness.c:2749
blessed
static int blessed(struct witness *, struct witness *)
Definition: subr_witness.c:2139
w_hash
static struct witness_hash w_hash
Definition: subr_witness.c:478
find_instance
static struct lock_instance * find_instance(struct lock_list_entry *list, const struct lock_object *lock)
Definition: subr_witness.c:2230
witness_channel
witness_channel
Definition: subr_witness.c:426
WITNESS_NONE
@ WITNESS_NONE
Definition: subr_witness.c:429
WITNESS_LOG
@ WITNESS_LOG
Definition: subr_witness.c:428
WITNESS_CONSOLE
@ WITNESS_CONSOLE
Definition: subr_witness.c:427
witness_norelease
void witness_norelease(struct lock_object *lock)
Definition: subr_witness.c:2528
witness_display_spinlock
void witness_display_spinlock(struct lock_object *lock, struct thread *owner, int(*prnt)(const char *fmt,...))
Definition: subr_witness.c:2339
witness_lock_order_add
static int witness_lock_order_add(struct witness *parent, struct witness *child)
Definition: subr_witness.c:3057
witness_thread_exit
void witness_thread_exit(struct thread *td)
Definition: subr_witness.c:1763
WITNESS_ATOD
#define WITNESS_ATOD(x)
Definition: subr_witness.c:182
witness_save
void witness_save(struct lock_object *lock, const char **filep, int *linep)
Definition: subr_witness.c:2354
witness_output
static int witness_output(const char *fmt,...) __printflike(1
Definition: subr_witness.c:2262
witness_list_locks
int witness_list_locks(struct lock_list_entry **lock_list, int(*prnt)(const char *fmt,...))
Definition: subr_witness.c:2316
MAX_W_NAME
#define MAX_W_NAME
Definition: subr_witness.c:156
witness_hash_djb2
static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size)
Definition: subr_witness.c:2921
blessed_list
static struct witness_blessed blessed_list[]
Definition: subr_witness.c:729
witness_startup_count
int witness_startup_count(void)
Definition: subr_witness.c:771
witness_cold
static int witness_cold
Definition: subr_witness.c:747
order_lists
static struct witness_order_list_entry order_lists[]
Definition: subr_witness.c:492
pending_cnt
static u_int pending_cnt
Definition: subr_witness.c:467
isitmydescendant
static int isitmydescendant(struct witness *parent, struct witness *child)
Definition: subr_witness.c:2131
witness_voutput
static int witness_voutput(const char *fmt, va_list ap) __printflike(1
Definition: subr_witness.c:2274
WITNESS_INDEX_ASSERT
#define WITNESS_INDEX_ASSERT(i)
Definition: subr_witness.c:184
STAILQ_HEAD
STAILQ_HEAD(witness_list, witness)
witness_hash_get
static struct witness * witness_hash_get(const char *key)
Definition: subr_witness.c:2969
witness_enter_debugger
static void witness_enter_debugger(const char *msg)
Definition: subr_witness.c:3132
witness_setflag
static int static void witness_setflag(struct lock_object *lock, int flag, int set)
Definition: subr_witness.c:2498
w_lodata
static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]
Definition: subr_witness.c:481
mtx
struct mtx mtx
Definition: uipc_ktls.c:0
dummy
static int dummy
Definition: uipc_sockbuf.c:1785
buf
struct stat * buf
Definition: vfs_syscalls.c:2423
flag
int flag
Definition: vfs_syscalls.c:2116