2 * Copyright (c) 2008 Isilon Systems, Inc.
3 * Copyright (c) 2008 Ilya Maykov <ivmaykov@gmail.com>
4 * Copyright (c) 1998 Berkeley Software Design, Inc.
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 * 3. Berkeley Software Design Inc's name may not be used to endorse or
16 * promote products derived from this software without specific prior
19 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
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24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $
32 * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $
36 * Implementation of the `witness' lock verifier. Originally implemented for
37 * mutexes in BSD/OS. Extended to handle generic lock objects and lock
43 * Pronunciation: 'wit-n&s
45 * Etymology: Middle English witnesse, from Old English witnes knowledge,
46 * testimony, witness, from 2wit
47 * Date: before 12th century
48 * 1 : attestation of a fact or event : TESTIMONY
49 * 2 : one that gives evidence; specifically : one who testifies in
50 * a cause or before a judicial tribunal
51 * 3 : one asked to be present at a transaction so as to be able to
52 * testify to its having taken place
53 * 4 : one who has personal knowledge of something
54 * 5 a : something serving as evidence or proof : SIGN
55 * b : public affirmation by word or example of usually
56 * religious faith or conviction <the heroic witness to divine
58 * 6 capitalized : a member of the Jehovah's Witnesses
62 * Special rules concerning Giant and lock orders:
64 * 1) Giant must be acquired before any other mutexes. Stated another way,
65 * no other mutex may be held when Giant is acquired.
67 * 2) Giant must be released when blocking on a sleepable lock.
69 * This rule is less obvious, but is a result of Giant providing the same
70 * semantics as spl(). Basically, when a thread sleeps, it must release
71 * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule
74 * 3) Giant may be acquired before or after sleepable locks.
76 * This rule is also not quite as obvious. Giant may be acquired after
77 * a sleepable lock because it is a non-sleepable lock and non-sleepable
78 * locks may always be acquired while holding a sleepable lock. The second
79 * case, Giant before a sleepable lock, follows from rule 2) above. Suppose
80 * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1
81 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and
82 * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to
83 * execute. Thus, acquiring Giant both before and after a sleepable lock
84 * will not result in a lock order reversal.
87 #include <sys/cdefs.h>
88 __FBSDID("$FreeBSD$");
91 #include "opt_hwpmc_hooks.h"
92 #include "opt_stack.h"
93 #include "opt_witness.h"
95 #include <sys/param.h>
98 #include <sys/kernel.h>
100 #include <sys/lock.h>
101 #include <sys/malloc.h>
102 #include <sys/mutex.h>
103 #include <sys/priv.h>
104 #include <sys/proc.h>
105 #include <sys/sbuf.h>
106 #include <sys/sched.h>
107 #include <sys/stack.h>
108 #include <sys/sysctl.h>
109 #include <sys/systm.h>
115 #include <machine/stdarg.h>
117 #if !defined(DDB) && !defined(STACK)
118 #error "DDB or STACK options are required for WITNESS"
121 /* Note that these traces do not work with KTR_ALQ. */
123 #define KTR_WITNESS KTR_SUBSYS
125 #define KTR_WITNESS 0
128 #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */
129 #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */
130 #define LI_NORELEASE 0x00020000 /* Lock not allowed to be released. */
132 /* Define this to check for blessed mutexes */
135 #define WITNESS_COUNT 1024
136 #define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4)
137 #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */
138 #define WITNESS_PENDLIST 768
140 /* Allocate 256 KB of stack data space */
141 #define WITNESS_LO_DATA_COUNT 2048
143 /* Prime, gives load factor of ~2 at full load */
144 #define WITNESS_LO_HASH_SIZE 1021
147 * XXX: This is somewhat bogus, as we assume here that at most 2048 threads
148 * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should
149 * probably be safe for the most part, but it's still a SWAG.
151 #define LOCK_NCHILDREN 5
152 #define LOCK_CHILDCOUNT 2048
154 #define MAX_W_NAME 64
156 #define BADSTACK_SBUF_SIZE (256 * WITNESS_COUNT)
157 #define FULLGRAPH_SBUF_SIZE 512
160 * These flags go in the witness relationship matrix and describe the
161 * relationship between any two struct witness objects.
163 #define WITNESS_UNRELATED 0x00 /* No lock order relation. */
164 #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */
165 #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */
166 #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */
167 #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */
168 #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR)
169 #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT)
170 #define WITNESS_RELATED_MASK \
171 (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK)
172 #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been
174 #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */
175 #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */
176 #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */
178 /* Descendant to ancestor flags */
179 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2)
181 /* Ancestor to descendant flags */
182 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2)
184 #define WITNESS_INDEX_ASSERT(i) \
185 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < WITNESS_COUNT)
187 static MALLOC_DEFINE(M_WITNESS, "Witness", "Witness");
190 * Lock instances. A lock instance is the data associated with a lock while
191 * it is held by witness. For example, a lock instance will hold the
192 * recursion count of a lock. Lock instances are held in lists. Spin locks
193 * are held in a per-cpu list while sleep locks are held in per-thread list.
195 struct lock_instance {
196 struct lock_object *li_lock;
203 * A simple list type used to build the list of locks held by a thread
204 * or CPU. We can't simply embed the list in struct lock_object since a
205 * lock may be held by more than one thread if it is a shared lock. Locks
206 * are added to the head of the list, so we fill up each list entry from
207 * "the back" logically. To ease some of the arithmetic, we actually fill
208 * in each list entry the normal way (children[0] then children[1], etc.) but
209 * when we traverse the list we read children[count-1] as the first entry
210 * down to children[0] as the final entry.
212 struct lock_list_entry {
213 struct lock_list_entry *ll_next;
214 struct lock_instance ll_children[LOCK_NCHILDREN];
219 * The main witness structure. One of these per named lock type in the system
220 * (for example, "vnode interlock").
223 char w_name[MAX_W_NAME];
224 uint32_t w_index; /* Index in the relationship matrix */
225 struct lock_class *w_class;
226 STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */
227 STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */
228 struct witness *w_hash_next; /* Linked list in hash buckets. */
229 const char *w_file; /* File where last acquired */
230 uint32_t w_line; /* Line where last acquired */
232 uint16_t w_num_ancestors; /* direct/indirect
234 uint16_t w_num_descendants; /* direct/indirect
235 * descendant count */
237 unsigned w_displayed:1;
238 unsigned w_reversed:1;
241 STAILQ_HEAD(witness_list, witness);
244 * The witness hash table. Keys are witness names (const char *), elements are
245 * witness objects (struct witness *).
247 struct witness_hash {
248 struct witness *wh_array[WITNESS_HASH_SIZE];
254 * Key type for the lock order data hash table.
256 struct witness_lock_order_key {
261 struct witness_lock_order_data {
262 struct stack wlod_stack;
263 struct witness_lock_order_key wlod_key;
264 struct witness_lock_order_data *wlod_next;
268 * The witness lock order data hash table. Keys are witness index tuples
269 * (struct witness_lock_order_key), elements are lock order data objects
270 * (struct witness_lock_order_data).
272 struct witness_lock_order_hash {
273 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE];
279 struct witness_blessed {
285 struct witness_pendhelp {
287 struct lock_object *wh_lock;
290 struct witness_order_list_entry {
292 struct lock_class *w_class;
296 * Returns 0 if one of the locks is a spin lock and the other is not.
297 * Returns 1 otherwise.
300 witness_lock_type_equal(struct witness *w1, struct witness *w2)
303 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) ==
304 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)));
308 witness_lock_order_key_equal(const struct witness_lock_order_key *a,
309 const struct witness_lock_order_key *b)
312 return (a->from == b->from && a->to == b->to);
315 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask,
318 static void _witness_debugger(int cond, const char *msg);
320 static void adopt(struct witness *parent, struct witness *child);
322 static int blessed(struct witness *, struct witness *);
324 static void depart(struct witness *w);
325 static struct witness *enroll(const char *description,
326 struct lock_class *lock_class);
327 static struct lock_instance *find_instance(struct lock_list_entry *list,
328 struct lock_object *lock);
329 static int isitmychild(struct witness *parent, struct witness *child);
330 static int isitmydescendant(struct witness *parent, struct witness *child);
331 static void itismychild(struct witness *parent, struct witness *child);
332 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS);
333 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS);
334 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS);
335 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent);
337 static void witness_ddb_compute_levels(void);
338 static void witness_ddb_display(int(*)(const char *fmt, ...));
339 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...),
340 struct witness *, int indent);
341 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...),
342 struct witness_list *list);
343 static void witness_ddb_level_descendants(struct witness *parent, int l);
344 static void witness_ddb_list(struct thread *td);
346 static void witness_free(struct witness *m);
347 static struct witness *witness_get(void);
348 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size);
349 static struct witness *witness_hash_get(const char *key);
350 static void witness_hash_put(struct witness *w);
351 static void witness_init_hash_tables(void);
352 static void witness_increment_graph_generation(void);
353 static void witness_lock_list_free(struct lock_list_entry *lle);
354 static struct lock_list_entry *witness_lock_list_get(void);
355 static int witness_lock_order_add(struct witness *parent,
356 struct witness *child);
357 static int witness_lock_order_check(struct witness *parent,
358 struct witness *child);
359 static struct witness_lock_order_data *witness_lock_order_get(
360 struct witness *parent,
361 struct witness *child);
362 static void witness_list_lock(struct lock_instance *instance,
363 int (*prnt)(const char *fmt, ...));
364 static void witness_setflag(struct lock_object *lock, int flag, int set);
367 #define witness_debugger(c) _witness_debugger(c, __func__)
369 #define witness_debugger(c)
372 static SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL,
376 * If set to 0, lock order checking is disabled. If set to -1,
377 * witness is completely disabled. Otherwise witness performs full
378 * lock order checking for all locks. At runtime, lock order checking
379 * may be toggled. However, witness cannot be reenabled once it is
380 * completely disabled.
382 static int witness_watch = 1;
383 TUNABLE_INT("debug.witness.watch", &witness_watch);
384 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0,
385 sysctl_debug_witness_watch, "I", "witness is watching lock operations");
389 * When KDB is enabled and witness_kdb is 1, it will cause the system
390 * to drop into kdebug() when:
391 * - a lock hierarchy violation occurs
392 * - locks are held when going to sleep.
399 TUNABLE_INT("debug.witness.kdb", &witness_kdb);
400 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, "");
403 * When KDB is enabled and witness_trace is 1, it will cause the system
404 * to print a stack trace:
405 * - a lock hierarchy violation occurs
406 * - locks are held when going to sleep.
408 int witness_trace = 1;
409 TUNABLE_INT("debug.witness.trace", &witness_trace);
410 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, "");
413 #ifdef WITNESS_SKIPSPIN
414 int witness_skipspin = 1;
416 int witness_skipspin = 0;
418 TUNABLE_INT("debug.witness.skipspin", &witness_skipspin);
419 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin,
423 * Call this to print out the relations between locks.
425 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD,
426 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs");
429 * Call this to print out the witness faulty stacks.
431 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD,
432 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks");
434 static struct mtx w_mtx;
437 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free);
438 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all);
441 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin);
442 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep);
445 static struct lock_list_entry *w_lock_list_free = NULL;
446 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST];
447 static u_int pending_cnt;
449 static int w_free_cnt, w_spin_cnt, w_sleep_cnt;
450 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, "");
451 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, "");
452 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0,
455 static struct witness *w_data;
456 static uint8_t w_rmatrix[WITNESS_COUNT+1][WITNESS_COUNT+1];
457 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT];
458 static struct witness_hash w_hash; /* The witness hash table. */
460 /* The lock order data hash */
461 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT];
462 static struct witness_lock_order_data *w_lofree = NULL;
463 static struct witness_lock_order_hash w_lohash;
464 static int w_max_used_index = 0;
465 static unsigned int w_generation = 0;
466 static const char w_notrunning[] = "Witness not running\n";
467 static const char w_stillcold[] = "Witness is still cold\n";
470 static struct witness_order_list_entry order_lists[] = {
474 { "proctree", &lock_class_sx },
475 { "allproc", &lock_class_sx },
476 { "allprison", &lock_class_sx },
481 { "Giant", &lock_class_mtx_sleep },
482 { "pipe mutex", &lock_class_mtx_sleep },
483 { "sigio lock", &lock_class_mtx_sleep },
484 { "process group", &lock_class_mtx_sleep },
485 { "process lock", &lock_class_mtx_sleep },
486 { "session", &lock_class_mtx_sleep },
487 { "uidinfo hash", &lock_class_rw },
489 { "pmc-sleep", &lock_class_mtx_sleep },
491 { "time lock", &lock_class_mtx_sleep },
496 { "accept", &lock_class_mtx_sleep },
497 { "so_snd", &lock_class_mtx_sleep },
498 { "so_rcv", &lock_class_mtx_sleep },
499 { "sellck", &lock_class_mtx_sleep },
504 { "so_rcv", &lock_class_mtx_sleep },
505 { "radix node head", &lock_class_rw },
506 { "rtentry", &lock_class_mtx_sleep },
507 { "ifaddr", &lock_class_mtx_sleep },
511 * protocol locks before interface locks, after UDP locks.
513 { "udpinp", &lock_class_rw },
514 { "in_multi_mtx", &lock_class_mtx_sleep },
515 { "igmp_mtx", &lock_class_mtx_sleep },
516 { "if_addr_mtx", &lock_class_mtx_sleep },
520 * protocol locks before interface locks, after UDP locks.
522 { "udpinp", &lock_class_rw },
523 { "in6_multi_mtx", &lock_class_mtx_sleep },
524 { "mld_mtx", &lock_class_mtx_sleep },
525 { "if_addr_mtx", &lock_class_mtx_sleep },
528 * UNIX Domain Sockets
530 { "unp_global_rwlock", &lock_class_rw },
531 { "unp_list_lock", &lock_class_mtx_sleep },
532 { "unp", &lock_class_mtx_sleep },
533 { "so_snd", &lock_class_mtx_sleep },
538 { "udp", &lock_class_rw },
539 { "udpinp", &lock_class_rw },
540 { "so_snd", &lock_class_mtx_sleep },
545 { "tcp", &lock_class_rw },
546 { "tcpinp", &lock_class_rw },
547 { "so_snd", &lock_class_mtx_sleep },
552 { "ddp_list_mtx", &lock_class_mtx_sleep },
553 { "ddp_mtx", &lock_class_mtx_sleep },
558 { "bpf global lock", &lock_class_mtx_sleep },
559 { "bpf interface lock", &lock_class_rw },
560 { "bpf cdev lock", &lock_class_mtx_sleep },
565 { "nfsd_mtx", &lock_class_mtx_sleep },
566 { "so_snd", &lock_class_mtx_sleep },
572 { "802.11 com lock", &lock_class_mtx_sleep},
577 { "network driver", &lock_class_mtx_sleep},
583 { "ng_node", &lock_class_mtx_sleep },
584 { "ng_worklist", &lock_class_mtx_sleep },
589 { "vm map (system)", &lock_class_mtx_sleep },
590 { "vm page queue", &lock_class_mtx_sleep },
591 { "vnode interlock", &lock_class_mtx_sleep },
592 { "cdev", &lock_class_mtx_sleep },
597 { "vm map (user)", &lock_class_sx },
598 { "vm object", &lock_class_mtx_sleep },
599 { "vm page", &lock_class_mtx_sleep },
600 { "vm page queue", &lock_class_mtx_sleep },
601 { "pmap pv global", &lock_class_rw },
602 { "pmap", &lock_class_mtx_sleep },
603 { "pmap pv list", &lock_class_rw },
604 { "vm page free queue", &lock_class_mtx_sleep },
607 * kqueue/VFS interaction
609 { "kqueue", &lock_class_mtx_sleep },
610 { "struct mount mtx", &lock_class_mtx_sleep },
611 { "vnode interlock", &lock_class_mtx_sleep },
616 { "dn->dn_mtx", &lock_class_sx },
617 { "dr->dt.di.dr_mtx", &lock_class_sx },
618 { "db->db_mtx", &lock_class_sx },
624 { "ap boot", &lock_class_mtx_spin },
626 { "rm.mutex_mtx", &lock_class_mtx_spin },
627 { "sio", &lock_class_mtx_spin },
628 { "scrlock", &lock_class_mtx_spin },
630 { "cy", &lock_class_mtx_spin },
633 { "pcib_mtx", &lock_class_mtx_spin },
634 { "rtc_mtx", &lock_class_mtx_spin },
636 { "scc_hwmtx", &lock_class_mtx_spin },
637 { "uart_hwmtx", &lock_class_mtx_spin },
638 { "fast_taskqueue", &lock_class_mtx_spin },
639 { "intr table", &lock_class_mtx_spin },
641 { "pmc-per-proc", &lock_class_mtx_spin },
643 { "process slock", &lock_class_mtx_spin },
644 { "sleepq chain", &lock_class_mtx_spin },
645 { "umtx lock", &lock_class_mtx_spin },
646 { "rm_spinlock", &lock_class_mtx_spin },
647 { "turnstile chain", &lock_class_mtx_spin },
648 { "turnstile lock", &lock_class_mtx_spin },
649 { "sched lock", &lock_class_mtx_spin },
650 { "td_contested", &lock_class_mtx_spin },
651 { "callout", &lock_class_mtx_spin },
652 { "entropy harvest mutex", &lock_class_mtx_spin },
653 { "syscons video lock", &lock_class_mtx_spin },
655 { "smp rendezvous", &lock_class_mtx_spin },
658 { "tlb0", &lock_class_mtx_spin },
663 { "intrcnt", &lock_class_mtx_spin },
664 { "icu", &lock_class_mtx_spin },
666 { "allpmaps", &lock_class_mtx_spin },
667 { "descriptor tables", &lock_class_mtx_spin },
669 { "clk", &lock_class_mtx_spin },
670 { "cpuset", &lock_class_mtx_spin },
671 { "mprof lock", &lock_class_mtx_spin },
672 { "zombie lock", &lock_class_mtx_spin },
673 { "ALD Queue", &lock_class_mtx_spin },
675 { "MCA spin lock", &lock_class_mtx_spin },
677 #if defined(__i386__) || defined(__amd64__)
678 { "pcicfg", &lock_class_mtx_spin },
679 { "NDIS thread lock", &lock_class_mtx_spin },
681 { "tw_osl_io_lock", &lock_class_mtx_spin },
682 { "tw_osl_q_lock", &lock_class_mtx_spin },
683 { "tw_cl_io_lock", &lock_class_mtx_spin },
684 { "tw_cl_intr_lock", &lock_class_mtx_spin },
685 { "tw_cl_gen_lock", &lock_class_mtx_spin },
687 { "pmc-leaf", &lock_class_mtx_spin },
689 { "blocked lock", &lock_class_mtx_spin },
696 * Pairs of locks which have been blessed
697 * Don't complain about order problems with blessed locks
699 static struct witness_blessed blessed_list[] = {
701 static int blessed_count =
702 sizeof(blessed_list) / sizeof(struct witness_blessed);
706 * This global is set to 0 once it becomes safe to use the witness code.
708 static int witness_cold = 1;
711 * This global is set to 1 once the static lock orders have been enrolled
712 * so that a warning can be issued for any spin locks enrolled later.
714 static int witness_spin_warn = 0;
716 /* Trim useless garbage from filenames. */
718 fixup_filename(const char *file)
723 while (strncmp(file, "../", 3) == 0)
729 * The WITNESS-enabled diagnostic code. Note that the witness code does
730 * assume that the early boot is single-threaded at least until after this
731 * routine is completed.
734 witness_initialize(void *dummy __unused)
736 struct lock_object *lock;
737 struct witness_order_list_entry *order;
738 struct witness *w, *w1;
741 w_data = malloc(sizeof (struct witness) * WITNESS_COUNT, M_WITNESS,
745 * We have to release Giant before initializing its witness
746 * structure so that WITNESS doesn't get confused.
749 mtx_assert(&Giant, MA_NOTOWNED);
751 CTR1(KTR_WITNESS, "%s: initializing witness", __func__);
752 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET |
753 MTX_NOWITNESS | MTX_NOPROFILE);
754 for (i = WITNESS_COUNT - 1; i >= 0; i--) {
756 memset(w, 0, sizeof(*w));
757 w_data[i].w_index = i; /* Witness index never changes. */
760 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0,
761 ("%s: Invalid list of free witness objects", __func__));
763 /* Witness with index 0 is not used to aid in debugging. */
764 STAILQ_REMOVE_HEAD(&w_free, w_list);
768 (sizeof(**w_rmatrix) * (WITNESS_COUNT+1) * (WITNESS_COUNT+1)));
770 for (i = 0; i < LOCK_CHILDCOUNT; i++)
771 witness_lock_list_free(&w_locklistdata[i]);
772 witness_init_hash_tables();
774 /* First add in all the specified order lists. */
775 for (order = order_lists; order->w_name != NULL; order++) {
776 w = enroll(order->w_name, order->w_class);
779 w->w_file = "order list";
780 for (order++; order->w_name != NULL; order++) {
781 w1 = enroll(order->w_name, order->w_class);
784 w1->w_file = "order list";
789 witness_spin_warn = 1;
791 /* Iterate through all locks and add them to witness. */
792 for (i = 0; pending_locks[i].wh_lock != NULL; i++) {
793 lock = pending_locks[i].wh_lock;
794 KASSERT(lock->lo_flags & LO_WITNESS,
795 ("%s: lock %s is on pending list but not LO_WITNESS",
796 __func__, lock->lo_name));
797 lock->lo_witness = enroll(pending_locks[i].wh_type,
801 /* Mark the witness code as being ready for use. */
806 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize,
810 witness_init(struct lock_object *lock, const char *type)
812 struct lock_class *class;
814 /* Various sanity checks. */
815 class = LOCK_CLASS(lock);
816 if ((lock->lo_flags & LO_RECURSABLE) != 0 &&
817 (class->lc_flags & LC_RECURSABLE) == 0)
818 panic("%s: lock (%s) %s can not be recursable", __func__,
819 class->lc_name, lock->lo_name);
820 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
821 (class->lc_flags & LC_SLEEPABLE) == 0)
822 panic("%s: lock (%s) %s can not be sleepable", __func__,
823 class->lc_name, lock->lo_name);
824 if ((lock->lo_flags & LO_UPGRADABLE) != 0 &&
825 (class->lc_flags & LC_UPGRADABLE) == 0)
826 panic("%s: lock (%s) %s can not be upgradable", __func__,
827 class->lc_name, lock->lo_name);
830 * If we shouldn't watch this lock, then just clear lo_witness.
831 * Otherwise, if witness_cold is set, then it is too early to
832 * enroll this lock, so defer it to witness_initialize() by adding
833 * it to the pending_locks list. If it is not too early, then enroll
836 if (witness_watch < 1 || panicstr != NULL ||
837 (lock->lo_flags & LO_WITNESS) == 0)
838 lock->lo_witness = NULL;
839 else if (witness_cold) {
840 pending_locks[pending_cnt].wh_lock = lock;
841 pending_locks[pending_cnt++].wh_type = type;
842 if (pending_cnt > WITNESS_PENDLIST)
843 panic("%s: pending locks list is too small, bump it\n",
846 lock->lo_witness = enroll(type, class);
850 witness_destroy(struct lock_object *lock)
852 struct lock_class *class;
855 class = LOCK_CLASS(lock);
858 panic("lock (%s) %s destroyed while witness_cold",
859 class->lc_name, lock->lo_name);
861 /* XXX: need to verify that no one holds the lock */
862 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL)
864 w = lock->lo_witness;
866 mtx_lock_spin(&w_mtx);
867 MPASS(w->w_refcount > 0);
870 if (w->w_refcount == 0)
872 mtx_unlock_spin(&w_mtx);
877 witness_ddb_compute_levels(void)
882 * First clear all levels.
884 STAILQ_FOREACH(w, &w_all, w_list)
888 * Look for locks with no parents and level all their descendants.
890 STAILQ_FOREACH(w, &w_all, w_list) {
892 /* If the witness has ancestors (is not a root), skip it. */
893 if (w->w_num_ancestors > 0)
895 witness_ddb_level_descendants(w, 0);
900 witness_ddb_level_descendants(struct witness *w, int l)
904 if (w->w_ddb_level >= l)
910 for (i = 1; i <= w_max_used_index; i++) {
911 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT)
912 witness_ddb_level_descendants(&w_data[i], l);
917 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...),
918 struct witness *w, int indent)
922 for (i = 0; i < indent; i++)
924 prnt("%s (type: %s, depth: %d, active refs: %d)",
925 w->w_name, w->w_class->lc_name,
926 w->w_ddb_level, w->w_refcount);
927 if (w->w_displayed) {
928 prnt(" -- (already displayed)\n");
932 if (w->w_file != NULL && w->w_line != 0)
933 prnt(" -- last acquired @ %s:%d\n", fixup_filename(w->w_file),
936 prnt(" -- never acquired\n");
938 WITNESS_INDEX_ASSERT(w->w_index);
939 for (i = 1; i <= w_max_used_index; i++) {
942 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT)
943 witness_ddb_display_descendants(prnt, &w_data[i],
949 witness_ddb_display_list(int(*prnt)(const char *fmt, ...),
950 struct witness_list *list)
954 STAILQ_FOREACH(w, list, w_typelist) {
955 if (w->w_file == NULL || w->w_ddb_level > 0)
958 /* This lock has no anscestors - display its descendants. */
959 witness_ddb_display_descendants(prnt, w, 0);
966 witness_ddb_display(int(*prnt)(const char *fmt, ...))
970 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
971 witness_ddb_compute_levels();
973 /* Clear all the displayed flags. */
974 STAILQ_FOREACH(w, &w_all, w_list)
978 * First, handle sleep locks which have been acquired at least
981 prnt("Sleep locks:\n");
982 witness_ddb_display_list(prnt, &w_sleep);
987 * Now do spin locks which have been acquired at least once.
989 prnt("\nSpin locks:\n");
990 witness_ddb_display_list(prnt, &w_spin);
995 * Finally, any locks which have not been acquired yet.
997 prnt("\nLocks which were never acquired:\n");
998 STAILQ_FOREACH(w, &w_all, w_list) {
999 if (w->w_file != NULL || w->w_refcount == 0)
1001 prnt("%s (type: %s, depth: %d)\n", w->w_name,
1002 w->w_class->lc_name, w->w_ddb_level);
1010 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2)
1013 if (witness_watch == -1 || panicstr != NULL)
1016 /* Require locks that witness knows about. */
1017 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL ||
1018 lock2->lo_witness == NULL)
1021 mtx_assert(&w_mtx, MA_NOTOWNED);
1022 mtx_lock_spin(&w_mtx);
1025 * If we already have either an explicit or implied lock order that
1026 * is the other way around, then return an error.
1028 if (witness_watch &&
1029 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) {
1030 mtx_unlock_spin(&w_mtx);
1034 /* Try to add the new order. */
1035 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
1036 lock2->lo_witness->w_name, lock1->lo_witness->w_name);
1037 itismychild(lock1->lo_witness, lock2->lo_witness);
1038 mtx_unlock_spin(&w_mtx);
1043 witness_checkorder(struct lock_object *lock, int flags, const char *file,
1044 int line, struct lock_object *interlock)
1046 struct lock_list_entry *lock_list, *lle;
1047 struct lock_instance *lock1, *lock2, *plock;
1048 struct lock_class *class;
1049 struct witness *w, *w1;
1053 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL ||
1057 w = lock->lo_witness;
1058 class = LOCK_CLASS(lock);
1061 if (class->lc_flags & LC_SLEEPLOCK) {
1064 * Since spin locks include a critical section, this check
1065 * implicitly enforces a lock order of all sleep locks before
1068 if (td->td_critnest != 0 && !kdb_active)
1069 panic("blockable sleep lock (%s) %s @ %s:%d",
1070 class->lc_name, lock->lo_name,
1071 fixup_filename(file), line);
1074 * If this is the first lock acquired then just return as
1075 * no order checking is needed.
1077 lock_list = td->td_sleeplocks;
1078 if (lock_list == NULL || lock_list->ll_count == 0)
1083 * If this is the first lock, just return as no order
1084 * checking is needed. Avoid problems with thread
1085 * migration pinning the thread while checking if
1086 * spinlocks are held. If at least one spinlock is held
1087 * the thread is in a safe path and it is allowed to
1091 lock_list = PCPU_GET(spinlocks);
1092 if (lock_list == NULL || lock_list->ll_count == 0) {
1100 * Check to see if we are recursing on a lock we already own. If
1101 * so, make sure that we don't mismatch exclusive and shared lock
1104 lock1 = find_instance(lock_list, lock);
1105 if (lock1 != NULL) {
1106 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 &&
1107 (flags & LOP_EXCLUSIVE) == 0) {
1108 printf("shared lock of (%s) %s @ %s:%d\n",
1109 class->lc_name, lock->lo_name,
1110 fixup_filename(file), line);
1111 printf("while exclusively locked from %s:%d\n",
1112 fixup_filename(lock1->li_file), lock1->li_line);
1113 panic("share->excl");
1115 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 &&
1116 (flags & LOP_EXCLUSIVE) != 0) {
1117 printf("exclusive lock of (%s) %s @ %s:%d\n",
1118 class->lc_name, lock->lo_name,
1119 fixup_filename(file), line);
1120 printf("while share locked from %s:%d\n",
1121 fixup_filename(lock1->li_file), lock1->li_line);
1122 panic("excl->share");
1128 * Find the previously acquired lock, but ignore interlocks.
1130 plock = &lock_list->ll_children[lock_list->ll_count - 1];
1131 if (interlock != NULL && plock->li_lock == interlock) {
1132 if (lock_list->ll_count > 1)
1134 &lock_list->ll_children[lock_list->ll_count - 2];
1136 lle = lock_list->ll_next;
1139 * The interlock is the only lock we hold, so
1144 plock = &lle->ll_children[lle->ll_count - 1];
1149 * Try to perform most checks without a lock. If this succeeds we
1150 * can skip acquiring the lock and return success.
1152 w1 = plock->li_lock->lo_witness;
1153 if (witness_lock_order_check(w1, w))
1157 * Check for duplicate locks of the same type. Note that we only
1158 * have to check for this on the last lock we just acquired. Any
1159 * other cases will be caught as lock order violations.
1161 mtx_lock_spin(&w_mtx);
1162 witness_lock_order_add(w1, w);
1165 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) &&
1166 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) {
1167 w_rmatrix[i][i] |= WITNESS_REVERSAL;
1169 mtx_unlock_spin(&w_mtx);
1171 "acquiring duplicate lock of same type: \"%s\"\n",
1173 printf(" 1st %s @ %s:%d\n", plock->li_lock->lo_name,
1174 fixup_filename(plock->li_file), plock->li_line);
1175 printf(" 2nd %s @ %s:%d\n", lock->lo_name,
1176 fixup_filename(file), line);
1177 witness_debugger(1);
1179 mtx_unlock_spin(&w_mtx);
1182 mtx_assert(&w_mtx, MA_OWNED);
1185 * If we know that the lock we are acquiring comes after
1186 * the lock we most recently acquired in the lock order tree,
1187 * then there is no need for any further checks.
1189 if (isitmychild(w1, w))
1192 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) {
1193 for (i = lle->ll_count - 1; i >= 0; i--, j++) {
1195 MPASS(j < WITNESS_COUNT);
1196 lock1 = &lle->ll_children[i];
1199 * Ignore the interlock the first time we see it.
1201 if (interlock != NULL && interlock == lock1->li_lock) {
1207 * If this lock doesn't undergo witness checking,
1210 w1 = lock1->li_lock->lo_witness;
1212 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0,
1213 ("lock missing witness structure"));
1218 * If we are locking Giant and this is a sleepable
1219 * lock, then skip it.
1221 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 &&
1222 lock == &Giant.lock_object)
1226 * If we are locking a sleepable lock and this lock
1227 * is Giant, then skip it.
1229 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1230 lock1->li_lock == &Giant.lock_object)
1234 * If we are locking a sleepable lock and this lock
1235 * isn't sleepable, we want to treat it as a lock
1236 * order violation to enfore a general lock order of
1237 * sleepable locks before non-sleepable locks.
1239 if (((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1240 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0))
1244 * If we are locking Giant and this is a non-sleepable
1245 * lock, then treat it as a reversal.
1247 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 &&
1248 lock == &Giant.lock_object)
1252 * Check the lock order hierarchy for a reveresal.
1254 if (!isitmydescendant(w, w1))
1259 * We have a lock order violation, check to see if it
1260 * is allowed or has already been yelled about.
1265 * If the lock order is blessed, just bail. We don't
1266 * look for other lock order violations though, which
1273 /* Bail if this violation is known */
1274 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL)
1277 /* Record this as a violation */
1278 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL;
1279 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL;
1280 w->w_reversed = w1->w_reversed = 1;
1281 witness_increment_graph_generation();
1282 mtx_unlock_spin(&w_mtx);
1285 * Ok, yell about it.
1287 if (((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1288 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0))
1290 "lock order reversal: (sleepable after non-sleepable)\n");
1291 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0
1292 && lock == &Giant.lock_object)
1294 "lock order reversal: (Giant after non-sleepable)\n");
1296 printf("lock order reversal:\n");
1299 * Try to locate an earlier lock with
1300 * witness w in our list.
1303 lock2 = &lle->ll_children[i];
1304 MPASS(lock2->li_lock != NULL);
1305 if (lock2->li_lock->lo_witness == w)
1307 if (i == 0 && lle->ll_next != NULL) {
1309 i = lle->ll_count - 1;
1310 MPASS(i >= 0 && i < LOCK_NCHILDREN);
1315 printf(" 1st %p %s (%s) @ %s:%d\n",
1316 lock1->li_lock, lock1->li_lock->lo_name,
1317 w1->w_name, fixup_filename(lock1->li_file),
1319 printf(" 2nd %p %s (%s) @ %s:%d\n", lock,
1320 lock->lo_name, w->w_name,
1321 fixup_filename(file), line);
1323 printf(" 1st %p %s (%s) @ %s:%d\n",
1324 lock2->li_lock, lock2->li_lock->lo_name,
1325 lock2->li_lock->lo_witness->w_name,
1326 fixup_filename(lock2->li_file),
1328 printf(" 2nd %p %s (%s) @ %s:%d\n",
1329 lock1->li_lock, lock1->li_lock->lo_name,
1330 w1->w_name, fixup_filename(lock1->li_file),
1332 printf(" 3rd %p %s (%s) @ %s:%d\n", lock,
1333 lock->lo_name, w->w_name,
1334 fixup_filename(file), line);
1336 witness_debugger(1);
1342 * If requested, build a new lock order. However, don't build a new
1343 * relationship between a sleepable lock and Giant if it is in the
1344 * wrong direction. The correct lock order is that sleepable locks
1345 * always come before Giant.
1347 if (flags & LOP_NEWORDER &&
1348 !(plock->li_lock == &Giant.lock_object &&
1349 (lock->lo_flags & LO_SLEEPABLE) != 0)) {
1350 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
1351 w->w_name, plock->li_lock->lo_witness->w_name);
1352 itismychild(plock->li_lock->lo_witness, w);
1355 mtx_unlock_spin(&w_mtx);
1359 witness_lock(struct lock_object *lock, int flags, const char *file, int line)
1361 struct lock_list_entry **lock_list, *lle;
1362 struct lock_instance *instance;
1366 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL ||
1369 w = lock->lo_witness;
1372 /* Determine lock list for this lock. */
1373 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK)
1374 lock_list = &td->td_sleeplocks;
1376 lock_list = PCPU_PTR(spinlocks);
1378 /* Check to see if we are recursing on a lock we already own. */
1379 instance = find_instance(*lock_list, lock);
1380 if (instance != NULL) {
1381 instance->li_flags++;
1382 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__,
1383 td->td_proc->p_pid, lock->lo_name,
1384 instance->li_flags & LI_RECURSEMASK);
1385 instance->li_file = file;
1386 instance->li_line = line;
1390 /* Update per-witness last file and line acquire. */
1394 /* Find the next open lock instance in the list and fill it. */
1396 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) {
1397 lle = witness_lock_list_get();
1400 lle->ll_next = *lock_list;
1401 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__,
1402 td->td_proc->p_pid, lle);
1405 instance = &lle->ll_children[lle->ll_count++];
1406 instance->li_lock = lock;
1407 instance->li_line = line;
1408 instance->li_file = file;
1409 if ((flags & LOP_EXCLUSIVE) != 0)
1410 instance->li_flags = LI_EXCLUSIVE;
1412 instance->li_flags = 0;
1413 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__,
1414 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1);
1418 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line)
1420 struct lock_instance *instance;
1421 struct lock_class *class;
1423 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1424 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
1426 class = LOCK_CLASS(lock);
1427 if (witness_watch) {
1428 if ((lock->lo_flags & LO_UPGRADABLE) == 0)
1429 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d",
1430 class->lc_name, lock->lo_name,
1431 fixup_filename(file), line);
1432 if ((class->lc_flags & LC_SLEEPLOCK) == 0)
1433 panic("upgrade of non-sleep lock (%s) %s @ %s:%d",
1434 class->lc_name, lock->lo_name,
1435 fixup_filename(file), line);
1437 instance = find_instance(curthread->td_sleeplocks, lock);
1438 if (instance == NULL)
1439 panic("upgrade of unlocked lock (%s) %s @ %s:%d",
1440 class->lc_name, lock->lo_name,
1441 fixup_filename(file), line);
1442 if (witness_watch) {
1443 if ((instance->li_flags & LI_EXCLUSIVE) != 0)
1444 panic("upgrade of exclusive lock (%s) %s @ %s:%d",
1445 class->lc_name, lock->lo_name,
1446 fixup_filename(file), line);
1447 if ((instance->li_flags & LI_RECURSEMASK) != 0)
1448 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d",
1449 class->lc_name, lock->lo_name,
1450 instance->li_flags & LI_RECURSEMASK,
1451 fixup_filename(file), line);
1453 instance->li_flags |= LI_EXCLUSIVE;
1457 witness_downgrade(struct lock_object *lock, int flags, const char *file,
1460 struct lock_instance *instance;
1461 struct lock_class *class;
1463 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1464 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
1466 class = LOCK_CLASS(lock);
1467 if (witness_watch) {
1468 if ((lock->lo_flags & LO_UPGRADABLE) == 0)
1469 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d",
1470 class->lc_name, lock->lo_name,
1471 fixup_filename(file), line);
1472 if ((class->lc_flags & LC_SLEEPLOCK) == 0)
1473 panic("downgrade of non-sleep lock (%s) %s @ %s:%d",
1474 class->lc_name, lock->lo_name,
1475 fixup_filename(file), line);
1477 instance = find_instance(curthread->td_sleeplocks, lock);
1478 if (instance == NULL)
1479 panic("downgrade of unlocked lock (%s) %s @ %s:%d",
1480 class->lc_name, lock->lo_name,
1481 fixup_filename(file), line);
1482 if (witness_watch) {
1483 if ((instance->li_flags & LI_EXCLUSIVE) == 0)
1484 panic("downgrade of shared lock (%s) %s @ %s:%d",
1485 class->lc_name, lock->lo_name,
1486 fixup_filename(file), line);
1487 if ((instance->li_flags & LI_RECURSEMASK) != 0)
1488 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d",
1489 class->lc_name, lock->lo_name,
1490 instance->li_flags & LI_RECURSEMASK,
1491 fixup_filename(file), line);
1493 instance->li_flags &= ~LI_EXCLUSIVE;
1497 witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
1499 struct lock_list_entry **lock_list, *lle;
1500 struct lock_instance *instance;
1501 struct lock_class *class;
1506 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL)
1509 class = LOCK_CLASS(lock);
1511 /* Find lock instance associated with this lock. */
1512 if (class->lc_flags & LC_SLEEPLOCK)
1513 lock_list = &td->td_sleeplocks;
1515 lock_list = PCPU_PTR(spinlocks);
1517 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next)
1518 for (i = 0; i < (*lock_list)->ll_count; i++) {
1519 instance = &(*lock_list)->ll_children[i];
1520 if (instance->li_lock == lock)
1525 * When disabling WITNESS through witness_watch we could end up in
1526 * having registered locks in the td_sleeplocks queue.
1527 * We have to make sure we flush these queues, so just search for
1528 * eventual register locks and remove them.
1530 if (witness_watch > 0)
1531 panic("lock (%s) %s not locked @ %s:%d", class->lc_name,
1532 lock->lo_name, fixup_filename(file), line);
1537 /* First, check for shared/exclusive mismatches. */
1538 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 &&
1539 (flags & LOP_EXCLUSIVE) == 0) {
1540 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name,
1541 lock->lo_name, fixup_filename(file), line);
1542 printf("while exclusively locked from %s:%d\n",
1543 fixup_filename(instance->li_file), instance->li_line);
1544 panic("excl->ushare");
1546 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 &&
1547 (flags & LOP_EXCLUSIVE) != 0) {
1548 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name,
1549 lock->lo_name, fixup_filename(file), line);
1550 printf("while share locked from %s:%d\n",
1551 fixup_filename(instance->li_file),
1553 panic("share->uexcl");
1555 /* If we are recursed, unrecurse. */
1556 if ((instance->li_flags & LI_RECURSEMASK) > 0) {
1557 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__,
1558 td->td_proc->p_pid, instance->li_lock->lo_name,
1559 instance->li_flags);
1560 instance->li_flags--;
1563 /* The lock is now being dropped, check for NORELEASE flag */
1564 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) {
1565 printf("forbidden unlock of (%s) %s @ %s:%d\n", class->lc_name,
1566 lock->lo_name, fixup_filename(file), line);
1567 panic("lock marked norelease");
1570 /* Otherwise, remove this item from the list. */
1572 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__,
1573 td->td_proc->p_pid, instance->li_lock->lo_name,
1574 (*lock_list)->ll_count - 1);
1575 for (j = i; j < (*lock_list)->ll_count - 1; j++)
1576 (*lock_list)->ll_children[j] =
1577 (*lock_list)->ll_children[j + 1];
1578 (*lock_list)->ll_count--;
1582 * In order to reduce contention on w_mtx, we want to keep always an
1583 * head object into lists so that frequent allocation from the
1584 * free witness pool (and subsequent locking) is avoided.
1585 * In order to maintain the current code simple, when the head
1586 * object is totally unloaded it means also that we do not have
1587 * further objects in the list, so the list ownership needs to be
1588 * hand over to another object if the current head needs to be freed.
1590 if ((*lock_list)->ll_count == 0) {
1591 if (*lock_list == lle) {
1592 if (lle->ll_next == NULL)
1596 *lock_list = lle->ll_next;
1597 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__,
1598 td->td_proc->p_pid, lle);
1599 witness_lock_list_free(lle);
1604 witness_thread_exit(struct thread *td)
1606 struct lock_list_entry *lle;
1609 lle = td->td_sleeplocks;
1610 if (lle == NULL || panicstr != NULL)
1612 if (lle->ll_count != 0) {
1613 for (n = 0; lle != NULL; lle = lle->ll_next)
1614 for (i = lle->ll_count - 1; i >= 0; i--) {
1616 printf("Thread %p exiting with the following locks held:\n",
1619 witness_list_lock(&lle->ll_children[i], printf);
1622 panic("Thread %p cannot exit while holding sleeplocks\n", td);
1624 witness_lock_list_free(lle);
1628 * Warn if any locks other than 'lock' are held. Flags can be passed in to
1629 * exempt Giant and sleepable locks from the checks as well. If any
1630 * non-exempt locks are held, then a supplied message is printed to the
1631 * console along with a list of the offending locks. If indicated in the
1632 * flags then a failure results in a panic as well.
1635 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...)
1637 struct lock_list_entry *lock_list, *lle;
1638 struct lock_instance *lock1;
1643 if (witness_cold || witness_watch < 1 || panicstr != NULL)
1647 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next)
1648 for (i = lle->ll_count - 1; i >= 0; i--) {
1649 lock1 = &lle->ll_children[i];
1650 if (lock1->li_lock == lock)
1652 if (flags & WARN_GIANTOK &&
1653 lock1->li_lock == &Giant.lock_object)
1655 if (flags & WARN_SLEEPOK &&
1656 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0)
1662 printf(" with the following");
1663 if (flags & WARN_SLEEPOK)
1664 printf(" non-sleepable");
1665 printf(" locks held:\n");
1668 witness_list_lock(lock1, printf);
1672 * Pin the thread in order to avoid problems with thread migration.
1673 * Once that all verifies are passed about spinlocks ownership,
1674 * the thread is in a safe path and it can be unpinned.
1677 lock_list = PCPU_GET(spinlocks);
1678 if (lock_list != NULL && lock_list->ll_count != 0) {
1682 * We should only have one spinlock and as long as
1683 * the flags cannot match for this locks class,
1684 * check if the first spinlock is the one curthread
1687 lock1 = &lock_list->ll_children[lock_list->ll_count - 1];
1688 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL &&
1689 lock1->li_lock == lock && n == 0)
1695 printf(" with the following");
1696 if (flags & WARN_SLEEPOK)
1697 printf(" non-sleepable");
1698 printf(" locks held:\n");
1699 n += witness_list_locks(&lock_list, printf);
1702 if (flags & WARN_PANIC && n)
1703 panic("%s", __func__);
1705 witness_debugger(n);
1710 witness_file(struct lock_object *lock)
1714 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
1716 w = lock->lo_witness;
1721 witness_line(struct lock_object *lock)
1725 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
1727 w = lock->lo_witness;
1731 static struct witness *
1732 enroll(const char *description, struct lock_class *lock_class)
1735 struct witness_list *typelist;
1737 MPASS(description != NULL);
1739 if (witness_watch == -1 || panicstr != NULL)
1741 if ((lock_class->lc_flags & LC_SPINLOCK)) {
1742 if (witness_skipspin)
1746 } else if ((lock_class->lc_flags & LC_SLEEPLOCK))
1747 typelist = &w_sleep;
1749 panic("lock class %s is not sleep or spin",
1750 lock_class->lc_name);
1752 mtx_lock_spin(&w_mtx);
1753 w = witness_hash_get(description);
1756 if ((w = witness_get()) == NULL)
1758 MPASS(strlen(description) < MAX_W_NAME);
1759 strcpy(w->w_name, description);
1760 w->w_class = lock_class;
1762 STAILQ_INSERT_HEAD(&w_all, w, w_list);
1763 if (lock_class->lc_flags & LC_SPINLOCK) {
1764 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist);
1766 } else if (lock_class->lc_flags & LC_SLEEPLOCK) {
1767 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist);
1771 /* Insert new witness into the hash */
1772 witness_hash_put(w);
1773 witness_increment_graph_generation();
1774 mtx_unlock_spin(&w_mtx);
1778 mtx_unlock_spin(&w_mtx);
1779 if (lock_class != w->w_class)
1781 "lock (%s) %s does not match earlier (%s) lock",
1782 description, lock_class->lc_name,
1783 w->w_class->lc_name);
1788 depart(struct witness *w)
1790 struct witness_list *list;
1792 MPASS(w->w_refcount == 0);
1793 if (w->w_class->lc_flags & LC_SLEEPLOCK) {
1801 * Set file to NULL as it may point into a loadable module.
1805 witness_increment_graph_generation();
1810 adopt(struct witness *parent, struct witness *child)
1814 if (witness_cold == 0)
1815 mtx_assert(&w_mtx, MA_OWNED);
1817 /* If the relationship is already known, there's no work to be done. */
1818 if (isitmychild(parent, child))
1821 /* When the structure of the graph changes, bump up the generation. */
1822 witness_increment_graph_generation();
1825 * The hard part ... create the direct relationship, then propagate all
1826 * indirect relationships.
1828 pi = parent->w_index;
1829 ci = child->w_index;
1830 WITNESS_INDEX_ASSERT(pi);
1831 WITNESS_INDEX_ASSERT(ci);
1833 w_rmatrix[pi][ci] |= WITNESS_PARENT;
1834 w_rmatrix[ci][pi] |= WITNESS_CHILD;
1837 * If parent was not already an ancestor of child,
1838 * then we increment the descendant and ancestor counters.
1840 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) {
1841 parent->w_num_descendants++;
1842 child->w_num_ancestors++;
1846 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as
1847 * an ancestor of 'pi' during this loop.
1849 for (i = 1; i <= w_max_used_index; i++) {
1850 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 &&
1854 /* Find each descendant of 'i' and mark it as a descendant. */
1855 for (j = 1; j <= w_max_used_index; j++) {
1858 * Skip children that are already marked as
1859 * descendants of 'i'.
1861 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK)
1865 * We are only interested in descendants of 'ci'. Note
1866 * that 'ci' itself is counted as a descendant of 'ci'.
1868 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 &&
1871 w_rmatrix[i][j] |= WITNESS_ANCESTOR;
1872 w_rmatrix[j][i] |= WITNESS_DESCENDANT;
1873 w_data[i].w_num_descendants++;
1874 w_data[j].w_num_ancestors++;
1877 * Make sure we aren't marking a node as both an
1878 * ancestor and descendant. We should have caught
1879 * this as a lock order reversal earlier.
1881 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) &&
1882 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) {
1883 printf("witness rmatrix paradox! [%d][%d]=%d "
1884 "both ancestor and descendant\n",
1885 i, j, w_rmatrix[i][j]);
1887 printf("Witness disabled.\n");
1890 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) &&
1891 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) {
1892 printf("witness rmatrix paradox! [%d][%d]=%d "
1893 "both ancestor and descendant\n",
1894 j, i, w_rmatrix[j][i]);
1896 printf("Witness disabled.\n");
1904 itismychild(struct witness *parent, struct witness *child)
1907 MPASS(child != NULL && parent != NULL);
1908 if (witness_cold == 0)
1909 mtx_assert(&w_mtx, MA_OWNED);
1911 if (!witness_lock_type_equal(parent, child)) {
1912 if (witness_cold == 0)
1913 mtx_unlock_spin(&w_mtx);
1914 panic("%s: parent \"%s\" (%s) and child \"%s\" (%s) are not "
1915 "the same lock type", __func__, parent->w_name,
1916 parent->w_class->lc_name, child->w_name,
1917 child->w_class->lc_name);
1919 adopt(parent, child);
1923 * Generic code for the isitmy*() functions. The rmask parameter is the
1924 * expected relationship of w1 to w2.
1927 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname)
1929 unsigned char r1, r2;
1934 WITNESS_INDEX_ASSERT(i1);
1935 WITNESS_INDEX_ASSERT(i2);
1936 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK;
1937 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK;
1939 /* The flags on one better be the inverse of the flags on the other */
1940 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) ||
1941 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) {
1942 printf("%s: rmatrix mismatch between %s (index %d) and %s "
1943 "(index %d): w_rmatrix[%d][%d] == %hhx but "
1944 "w_rmatrix[%d][%d] == %hhx\n",
1945 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1,
1948 printf("Witness disabled.\n");
1951 return (r1 & rmask);
1955 * Checks if @child is a direct child of @parent.
1958 isitmychild(struct witness *parent, struct witness *child)
1961 return (_isitmyx(parent, child, WITNESS_PARENT, __func__));
1965 * Checks if @descendant is a direct or inderect descendant of @ancestor.
1968 isitmydescendant(struct witness *ancestor, struct witness *descendant)
1971 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK,
1977 blessed(struct witness *w1, struct witness *w2)
1980 struct witness_blessed *b;
1982 for (i = 0; i < blessed_count; i++) {
1983 b = &blessed_list[i];
1984 if (strcmp(w1->w_name, b->b_lock1) == 0) {
1985 if (strcmp(w2->w_name, b->b_lock2) == 0)
1989 if (strcmp(w1->w_name, b->b_lock2) == 0)
1990 if (strcmp(w2->w_name, b->b_lock1) == 0)
1997 static struct witness *
2003 if (witness_cold == 0)
2004 mtx_assert(&w_mtx, MA_OWNED);
2006 if (witness_watch == -1) {
2007 mtx_unlock_spin(&w_mtx);
2010 if (STAILQ_EMPTY(&w_free)) {
2012 mtx_unlock_spin(&w_mtx);
2013 printf("WITNESS: unable to allocate a new witness object\n");
2016 w = STAILQ_FIRST(&w_free);
2017 STAILQ_REMOVE_HEAD(&w_free, w_list);
2020 MPASS(index > 0 && index == w_max_used_index+1 &&
2021 index < WITNESS_COUNT);
2022 bzero(w, sizeof(*w));
2024 if (index > w_max_used_index)
2025 w_max_used_index = index;
2030 witness_free(struct witness *w)
2033 STAILQ_INSERT_HEAD(&w_free, w, w_list);
2037 static struct lock_list_entry *
2038 witness_lock_list_get(void)
2040 struct lock_list_entry *lle;
2042 if (witness_watch == -1)
2044 mtx_lock_spin(&w_mtx);
2045 lle = w_lock_list_free;
2048 mtx_unlock_spin(&w_mtx);
2049 printf("%s: witness exhausted\n", __func__);
2052 w_lock_list_free = lle->ll_next;
2053 mtx_unlock_spin(&w_mtx);
2054 bzero(lle, sizeof(*lle));
2059 witness_lock_list_free(struct lock_list_entry *lle)
2062 mtx_lock_spin(&w_mtx);
2063 lle->ll_next = w_lock_list_free;
2064 w_lock_list_free = lle;
2065 mtx_unlock_spin(&w_mtx);
2068 static struct lock_instance *
2069 find_instance(struct lock_list_entry *list, struct lock_object *lock)
2071 struct lock_list_entry *lle;
2072 struct lock_instance *instance;
2075 for (lle = list; lle != NULL; lle = lle->ll_next)
2076 for (i = lle->ll_count - 1; i >= 0; i--) {
2077 instance = &lle->ll_children[i];
2078 if (instance->li_lock == lock)
2085 witness_list_lock(struct lock_instance *instance,
2086 int (*prnt)(const char *fmt, ...))
2088 struct lock_object *lock;
2090 lock = instance->li_lock;
2091 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ?
2092 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name);
2093 if (lock->lo_witness->w_name != lock->lo_name)
2094 prnt(" (%s)", lock->lo_witness->w_name);
2095 prnt(" r = %d (%p) locked @ %s:%d\n",
2096 instance->li_flags & LI_RECURSEMASK, lock,
2097 fixup_filename(instance->li_file), instance->li_line);
2102 witness_thread_has_locks(struct thread *td)
2105 if (td->td_sleeplocks == NULL)
2107 return (td->td_sleeplocks->ll_count != 0);
2111 witness_proc_has_locks(struct proc *p)
2115 FOREACH_THREAD_IN_PROC(p, td) {
2116 if (witness_thread_has_locks(td))
2124 witness_list_locks(struct lock_list_entry **lock_list,
2125 int (*prnt)(const char *fmt, ...))
2127 struct lock_list_entry *lle;
2131 for (lle = *lock_list; lle != NULL; lle = lle->ll_next)
2132 for (i = lle->ll_count - 1; i >= 0; i--) {
2133 witness_list_lock(&lle->ll_children[i], prnt);
2140 * This is a bit risky at best. We call this function when we have timed
2141 * out acquiring a spin lock, and we assume that the other CPU is stuck
2142 * with this lock held. So, we go groveling around in the other CPU's
2143 * per-cpu data to try to find the lock instance for this spin lock to
2144 * see when it was last acquired.
2147 witness_display_spinlock(struct lock_object *lock, struct thread *owner,
2148 int (*prnt)(const char *fmt, ...))
2150 struct lock_instance *instance;
2153 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU)
2155 pc = pcpu_find(owner->td_oncpu);
2156 instance = find_instance(pc->pc_spinlocks, lock);
2157 if (instance != NULL)
2158 witness_list_lock(instance, prnt);
2162 witness_save(struct lock_object *lock, const char **filep, int *linep)
2164 struct lock_list_entry *lock_list;
2165 struct lock_instance *instance;
2166 struct lock_class *class;
2169 * This function is used independently in locking code to deal with
2170 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant
2173 if (SCHEDULER_STOPPED())
2175 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2176 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2178 class = LOCK_CLASS(lock);
2179 if (class->lc_flags & LC_SLEEPLOCK)
2180 lock_list = curthread->td_sleeplocks;
2182 if (witness_skipspin)
2184 lock_list = PCPU_GET(spinlocks);
2186 instance = find_instance(lock_list, lock);
2187 if (instance == NULL)
2188 panic("%s: lock (%s) %s not locked", __func__,
2189 class->lc_name, lock->lo_name);
2190 *filep = instance->li_file;
2191 *linep = instance->li_line;
2195 witness_restore(struct lock_object *lock, const char *file, int line)
2197 struct lock_list_entry *lock_list;
2198 struct lock_instance *instance;
2199 struct lock_class *class;
2202 * This function is used independently in locking code to deal with
2203 * Giant, SCHEDULER_STOPPED() check can be removed here after Giant
2206 if (SCHEDULER_STOPPED())
2208 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2209 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2211 class = LOCK_CLASS(lock);
2212 if (class->lc_flags & LC_SLEEPLOCK)
2213 lock_list = curthread->td_sleeplocks;
2215 if (witness_skipspin)
2217 lock_list = PCPU_GET(spinlocks);
2219 instance = find_instance(lock_list, lock);
2220 if (instance == NULL)
2221 panic("%s: lock (%s) %s not locked", __func__,
2222 class->lc_name, lock->lo_name);
2223 lock->lo_witness->w_file = file;
2224 lock->lo_witness->w_line = line;
2225 instance->li_file = file;
2226 instance->li_line = line;
2230 witness_assert(struct lock_object *lock, int flags, const char *file, int line)
2232 #ifdef INVARIANT_SUPPORT
2233 struct lock_instance *instance;
2234 struct lock_class *class;
2236 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL)
2238 class = LOCK_CLASS(lock);
2239 if ((class->lc_flags & LC_SLEEPLOCK) != 0)
2240 instance = find_instance(curthread->td_sleeplocks, lock);
2241 else if ((class->lc_flags & LC_SPINLOCK) != 0)
2242 instance = find_instance(PCPU_GET(spinlocks), lock);
2244 panic("Lock (%s) %s is not sleep or spin!",
2245 class->lc_name, lock->lo_name);
2249 if (instance != NULL)
2250 panic("Lock (%s) %s locked @ %s:%d.",
2251 class->lc_name, lock->lo_name,
2252 fixup_filename(file), line);
2255 case LA_LOCKED | LA_RECURSED:
2256 case LA_LOCKED | LA_NOTRECURSED:
2258 case LA_SLOCKED | LA_RECURSED:
2259 case LA_SLOCKED | LA_NOTRECURSED:
2261 case LA_XLOCKED | LA_RECURSED:
2262 case LA_XLOCKED | LA_NOTRECURSED:
2263 if (instance == NULL) {
2264 panic("Lock (%s) %s not locked @ %s:%d.",
2265 class->lc_name, lock->lo_name,
2266 fixup_filename(file), line);
2269 if ((flags & LA_XLOCKED) != 0 &&
2270 (instance->li_flags & LI_EXCLUSIVE) == 0)
2271 panic("Lock (%s) %s not exclusively locked @ %s:%d.",
2272 class->lc_name, lock->lo_name,
2273 fixup_filename(file), line);
2274 if ((flags & LA_SLOCKED) != 0 &&
2275 (instance->li_flags & LI_EXCLUSIVE) != 0)
2276 panic("Lock (%s) %s exclusively locked @ %s:%d.",
2277 class->lc_name, lock->lo_name,
2278 fixup_filename(file), line);
2279 if ((flags & LA_RECURSED) != 0 &&
2280 (instance->li_flags & LI_RECURSEMASK) == 0)
2281 panic("Lock (%s) %s not recursed @ %s:%d.",
2282 class->lc_name, lock->lo_name,
2283 fixup_filename(file), line);
2284 if ((flags & LA_NOTRECURSED) != 0 &&
2285 (instance->li_flags & LI_RECURSEMASK) != 0)
2286 panic("Lock (%s) %s recursed @ %s:%d.",
2287 class->lc_name, lock->lo_name,
2288 fixup_filename(file), line);
2291 panic("Invalid lock assertion at %s:%d.",
2292 fixup_filename(file), line);
2295 #endif /* INVARIANT_SUPPORT */
2299 witness_setflag(struct lock_object *lock, int flag, int set)
2301 struct lock_list_entry *lock_list;
2302 struct lock_instance *instance;
2303 struct lock_class *class;
2305 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2307 class = LOCK_CLASS(lock);
2308 if (class->lc_flags & LC_SLEEPLOCK)
2309 lock_list = curthread->td_sleeplocks;
2311 if (witness_skipspin)
2313 lock_list = PCPU_GET(spinlocks);
2315 instance = find_instance(lock_list, lock);
2316 if (instance == NULL)
2317 panic("%s: lock (%s) %s not locked", __func__,
2318 class->lc_name, lock->lo_name);
2321 instance->li_flags |= flag;
2323 instance->li_flags &= ~flag;
2327 witness_norelease(struct lock_object *lock)
2330 witness_setflag(lock, LI_NORELEASE, 1);
2334 witness_releaseok(struct lock_object *lock)
2337 witness_setflag(lock, LI_NORELEASE, 0);
2342 witness_ddb_list(struct thread *td)
2345 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2346 KASSERT(kdb_active, ("%s: not in the debugger", __func__));
2348 if (witness_watch < 1)
2351 witness_list_locks(&td->td_sleeplocks, db_printf);
2354 * We only handle spinlocks if td == curthread. This is somewhat broken
2355 * if td is currently executing on some other CPU and holds spin locks
2356 * as we won't display those locks. If we had a MI way of getting
2357 * the per-cpu data for a given cpu then we could use
2358 * td->td_oncpu to get the list of spinlocks for this thread
2361 * That still wouldn't really fix this unless we locked the scheduler
2362 * lock or stopped the other CPU to make sure it wasn't changing the
2363 * list out from under us. It is probably best to just not try to
2364 * handle threads on other CPU's for now.
2366 if (td == curthread && PCPU_GET(spinlocks) != NULL)
2367 witness_list_locks(PCPU_PTR(spinlocks), db_printf);
2370 DB_SHOW_COMMAND(locks, db_witness_list)
2375 td = db_lookup_thread(addr, TRUE);
2378 witness_ddb_list(td);
2381 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all)
2387 * It would be nice to list only threads and processes that actually
2388 * held sleep locks, but that information is currently not exported
2391 FOREACH_PROC_IN_SYSTEM(p) {
2392 if (!witness_proc_has_locks(p))
2394 FOREACH_THREAD_IN_PROC(p, td) {
2395 if (!witness_thread_has_locks(td))
2397 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid,
2398 p->p_comm, td, td->td_tid);
2399 witness_ddb_list(td);
2405 DB_SHOW_ALIAS(alllocks, db_witness_list_all)
2407 DB_SHOW_COMMAND(witness, db_witness_display)
2410 witness_ddb_display(db_printf);
2415 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS)
2417 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2;
2418 struct witness *tmp_w1, *tmp_w2, *w1, *w2;
2420 u_int w_rmatrix1, w_rmatrix2;
2421 int error, generation, i, j;
2427 if (witness_watch < 1) {
2428 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
2432 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
2436 sb = sbuf_new(NULL, NULL, BADSTACK_SBUF_SIZE, SBUF_AUTOEXTEND);
2440 /* Allocate and init temporary storage space. */
2441 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
2442 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
2443 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP,
2445 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP,
2447 stack_zero(&tmp_data1->wlod_stack);
2448 stack_zero(&tmp_data2->wlod_stack);
2451 mtx_lock_spin(&w_mtx);
2452 generation = w_generation;
2453 mtx_unlock_spin(&w_mtx);
2454 sbuf_printf(sb, "Number of known direct relationships is %d\n",
2455 w_lohash.wloh_count);
2456 for (i = 1; i < w_max_used_index; i++) {
2457 mtx_lock_spin(&w_mtx);
2458 if (generation != w_generation) {
2459 mtx_unlock_spin(&w_mtx);
2461 /* The graph has changed, try again. */
2468 if (w1->w_reversed == 0) {
2469 mtx_unlock_spin(&w_mtx);
2473 /* Copy w1 locally so we can release the spin lock. */
2475 mtx_unlock_spin(&w_mtx);
2477 if (tmp_w1->w_reversed == 0)
2479 for (j = 1; j < w_max_used_index; j++) {
2480 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j)
2483 mtx_lock_spin(&w_mtx);
2484 if (generation != w_generation) {
2485 mtx_unlock_spin(&w_mtx);
2487 /* The graph has changed, try again. */
2494 data1 = witness_lock_order_get(w1, w2);
2495 data2 = witness_lock_order_get(w2, w1);
2498 * Copy information locally so we can release the
2502 w_rmatrix1 = (unsigned int)w_rmatrix[i][j];
2503 w_rmatrix2 = (unsigned int)w_rmatrix[j][i];
2506 stack_zero(&tmp_data1->wlod_stack);
2507 stack_copy(&data1->wlod_stack,
2508 &tmp_data1->wlod_stack);
2510 if (data2 && data2 != data1) {
2511 stack_zero(&tmp_data2->wlod_stack);
2512 stack_copy(&data2->wlod_stack,
2513 &tmp_data2->wlod_stack);
2515 mtx_unlock_spin(&w_mtx);
2518 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n",
2519 tmp_w1->w_name, tmp_w1->w_class->lc_name,
2520 tmp_w2->w_name, tmp_w2->w_class->lc_name);
2523 "w_rmatrix[%s][%s] == %x, w_rmatrix[%s][%s] == %x\n",
2524 tmp_w1->name, tmp_w2->w_name, w_rmatrix1,
2525 tmp_w2->name, tmp_w1->w_name, w_rmatrix2);
2529 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
2530 tmp_w1->w_name, tmp_w1->w_class->lc_name,
2531 tmp_w2->w_name, tmp_w2->w_class->lc_name);
2532 stack_sbuf_print(sb, &tmp_data1->wlod_stack);
2533 sbuf_printf(sb, "\n");
2535 if (data2 && data2 != data1) {
2537 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
2538 tmp_w2->w_name, tmp_w2->w_class->lc_name,
2539 tmp_w1->w_name, tmp_w1->w_class->lc_name);
2540 stack_sbuf_print(sb, &tmp_data2->wlod_stack);
2541 sbuf_printf(sb, "\n");
2545 mtx_lock_spin(&w_mtx);
2546 if (generation != w_generation) {
2547 mtx_unlock_spin(&w_mtx);
2550 * The graph changed while we were printing stack data,
2557 mtx_unlock_spin(&w_mtx);
2559 /* Free temporary storage space. */
2560 free(tmp_data1, M_TEMP);
2561 free(tmp_data2, M_TEMP);
2562 free(tmp_w1, M_TEMP);
2563 free(tmp_w2, M_TEMP);
2566 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
2573 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS)
2579 if (witness_watch < 1) {
2580 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
2584 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
2589 error = sysctl_wire_old_buffer(req, 0);
2592 sb = sbuf_new_for_sysctl(NULL, NULL, FULLGRAPH_SBUF_SIZE, req);
2595 sbuf_printf(sb, "\n");
2597 mtx_lock_spin(&w_mtx);
2598 STAILQ_FOREACH(w, &w_all, w_list)
2600 STAILQ_FOREACH(w, &w_all, w_list)
2601 witness_add_fullgraph(sb, w);
2602 mtx_unlock_spin(&w_mtx);
2605 * Close the sbuf and return to userland.
2607 error = sbuf_finish(sb);
2614 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS)
2618 value = witness_watch;
2619 error = sysctl_handle_int(oidp, &value, 0, req);
2620 if (error != 0 || req->newptr == NULL)
2622 if (value > 1 || value < -1 ||
2623 (witness_watch == -1 && value != witness_watch))
2625 witness_watch = value;
2630 witness_add_fullgraph(struct sbuf *sb, struct witness *w)
2634 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0))
2638 WITNESS_INDEX_ASSERT(w->w_index);
2639 for (i = 1; i <= w_max_used_index; i++) {
2640 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) {
2641 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name,
2643 witness_add_fullgraph(sb, &w_data[i]);
2649 * A simple hash function. Takes a key pointer and a key size. If size == 0,
2650 * interprets the key as a string and reads until the null
2651 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit
2652 * hash value computed from the key.
2655 witness_hash_djb2(const uint8_t *key, uint32_t size)
2657 unsigned int hash = 5381;
2660 /* hash = hash * 33 + key[i] */
2662 for (i = 0; i < size; i++)
2663 hash = ((hash << 5) + hash) + (unsigned int)key[i];
2665 for (i = 0; key[i] != 0; i++)
2666 hash = ((hash << 5) + hash) + (unsigned int)key[i];
2673 * Initializes the two witness hash tables. Called exactly once from
2674 * witness_initialize().
2677 witness_init_hash_tables(void)
2681 MPASS(witness_cold);
2683 /* Initialize the hash tables. */
2684 for (i = 0; i < WITNESS_HASH_SIZE; i++)
2685 w_hash.wh_array[i] = NULL;
2687 w_hash.wh_size = WITNESS_HASH_SIZE;
2688 w_hash.wh_count = 0;
2690 /* Initialize the lock order data hash. */
2692 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) {
2693 memset(&w_lodata[i], 0, sizeof(w_lodata[i]));
2694 w_lodata[i].wlod_next = w_lofree;
2695 w_lofree = &w_lodata[i];
2697 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE;
2698 w_lohash.wloh_count = 0;
2699 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++)
2700 w_lohash.wloh_array[i] = NULL;
2703 static struct witness *
2704 witness_hash_get(const char *key)
2710 if (witness_cold == 0)
2711 mtx_assert(&w_mtx, MA_OWNED);
2712 hash = witness_hash_djb2(key, 0) % w_hash.wh_size;
2713 w = w_hash.wh_array[hash];
2715 if (strcmp(w->w_name, key) == 0)
2725 witness_hash_put(struct witness *w)
2730 MPASS(w->w_name != NULL);
2731 if (witness_cold == 0)
2732 mtx_assert(&w_mtx, MA_OWNED);
2733 KASSERT(witness_hash_get(w->w_name) == NULL,
2734 ("%s: trying to add a hash entry that already exists!", __func__));
2735 KASSERT(w->w_hash_next == NULL,
2736 ("%s: w->w_hash_next != NULL", __func__));
2738 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size;
2739 w->w_hash_next = w_hash.wh_array[hash];
2740 w_hash.wh_array[hash] = w;
2745 static struct witness_lock_order_data *
2746 witness_lock_order_get(struct witness *parent, struct witness *child)
2748 struct witness_lock_order_data *data = NULL;
2749 struct witness_lock_order_key key;
2752 MPASS(parent != NULL && child != NULL);
2753 key.from = parent->w_index;
2754 key.to = child->w_index;
2755 WITNESS_INDEX_ASSERT(key.from);
2756 WITNESS_INDEX_ASSERT(key.to);
2757 if ((w_rmatrix[parent->w_index][child->w_index]
2758 & WITNESS_LOCK_ORDER_KNOWN) == 0)
2761 hash = witness_hash_djb2((const char*)&key,
2762 sizeof(key)) % w_lohash.wloh_size;
2763 data = w_lohash.wloh_array[hash];
2764 while (data != NULL) {
2765 if (witness_lock_order_key_equal(&data->wlod_key, &key))
2767 data = data->wlod_next;
2775 * Verify that parent and child have a known relationship, are not the same,
2776 * and child is actually a child of parent. This is done without w_mtx
2777 * to avoid contention in the common case.
2780 witness_lock_order_check(struct witness *parent, struct witness *child)
2783 if (parent != child &&
2784 w_rmatrix[parent->w_index][child->w_index]
2785 & WITNESS_LOCK_ORDER_KNOWN &&
2786 isitmychild(parent, child))
2793 witness_lock_order_add(struct witness *parent, struct witness *child)
2795 struct witness_lock_order_data *data = NULL;
2796 struct witness_lock_order_key key;
2799 MPASS(parent != NULL && child != NULL);
2800 key.from = parent->w_index;
2801 key.to = child->w_index;
2802 WITNESS_INDEX_ASSERT(key.from);
2803 WITNESS_INDEX_ASSERT(key.to);
2804 if (w_rmatrix[parent->w_index][child->w_index]
2805 & WITNESS_LOCK_ORDER_KNOWN)
2808 hash = witness_hash_djb2((const char*)&key,
2809 sizeof(key)) % w_lohash.wloh_size;
2810 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN;
2814 w_lofree = data->wlod_next;
2815 data->wlod_next = w_lohash.wloh_array[hash];
2816 data->wlod_key = key;
2817 w_lohash.wloh_array[hash] = data;
2818 w_lohash.wloh_count++;
2819 stack_zero(&data->wlod_stack);
2820 stack_save(&data->wlod_stack);
2824 /* Call this whenver the structure of the witness graph changes. */
2826 witness_increment_graph_generation(void)
2829 if (witness_cold == 0)
2830 mtx_assert(&w_mtx, MA_OWNED);
2836 _witness_debugger(int cond, const char *msg)
2839 if (witness_trace && cond)
2841 if (witness_kdb && cond)
2842 kdb_enter(KDB_WHY_WITNESS, msg);