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
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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 512
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 CYCLEGRAPH_SBUF_SIZE 8192
158 #define FULLGRAPH_SBUF_SIZE 32768
161 * These flags go in the witness relationship matrix and describe the
162 * relationship between any two struct witness objects.
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
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. */
179 /* Descendant to ancestor flags */
180 #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2)
182 /* Ancestor to descendant flags */
183 #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2)
185 #define WITNESS_INDEX_ASSERT(i) \
186 MPASS((i) > 0 && (i) <= w_max_used_index && (i) < WITNESS_COUNT)
188 MALLOC_DEFINE(M_WITNESS, "Witness", "Witness");
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.
196 struct lock_instance {
197 struct lock_object *li_lock;
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.
213 struct lock_list_entry {
214 struct lock_list_entry *ll_next;
215 struct lock_instance ll_children[LOCK_NCHILDREN];
220 * The main witness structure. One of these per named lock type in the system
221 * (for example, "vnode interlock").
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 */
233 uint16_t w_num_ancestors; /* direct/indirect
235 uint16_t w_num_descendants; /* direct/indirect
236 * descendant count */
238 unsigned w_displayed:1;
239 unsigned w_reversed:1;
242 STAILQ_HEAD(witness_list, witness);
245 * The witness hash table. Keys are witness names (const char *), elements are
246 * witness objects (struct witness *).
248 struct witness_hash {
249 struct witness *wh_array[WITNESS_HASH_SIZE];
255 * Key type for the lock order data hash table.
257 struct witness_lock_order_key {
262 struct 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;
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).
273 struct witness_lock_order_hash {
274 struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE];
280 struct witness_blessed {
286 struct witness_pendhelp {
288 struct lock_object *wh_lock;
291 struct witness_order_list_entry {
293 struct lock_class *w_class;
297 * Returns 0 if one of the locks is a spin lock and the other is not.
298 * Returns 1 otherwise.
301 witness_lock_type_equal(struct witness *w1, struct witness *w2)
304 return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) ==
305 (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)));
309 witness_lock_order_key_empty(const struct witness_lock_order_key *key)
312 return (key->from == 0 && key->to == 0);
316 witness_lock_order_key_equal(const struct witness_lock_order_key *a,
317 const struct witness_lock_order_key *b)
320 return (a->from == b->from && a->to == b->to);
323 static int _isitmyx(struct witness *w1, struct witness *w2, int rmask,
326 static void _witness_debugger(int cond, const char *msg);
328 static void adopt(struct witness *parent, struct witness *child);
330 static int blessed(struct witness *, struct witness *);
332 static void depart(struct witness *w);
333 static struct witness *enroll(const char *description,
334 struct lock_class *lock_class);
335 static struct lock_instance *find_instance(struct lock_list_entry *list,
336 struct lock_object *lock);
337 static int isitmychild(struct witness *parent, struct witness *child);
338 static int isitmydescendant(struct witness *parent, struct witness *child);
339 static void itismychild(struct witness *parent, struct witness *child);
340 static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS);
341 static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS);
342 static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS);
343 static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent);
345 static void witness_ddb_compute_levels(void);
346 static void witness_ddb_display(int(*)(const char *fmt, ...));
347 static void witness_ddb_display_descendants(int(*)(const char *fmt, ...),
348 struct witness *, int indent);
349 static void witness_ddb_display_list(int(*prnt)(const char *fmt, ...),
350 struct witness_list *list);
351 static void witness_ddb_level_descendants(struct witness *parent, int l);
352 static void witness_ddb_list(struct thread *td);
354 static void witness_free(struct witness *m);
355 static struct witness *witness_get(void);
356 static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size);
357 static struct witness *witness_hash_get(const char *key);
358 static void witness_hash_put(struct witness *w);
359 static void witness_init_hash_tables(void);
360 static void witness_increment_graph_generation(void);
361 static void witness_lock_list_free(struct lock_list_entry *lle);
362 static struct lock_list_entry *witness_lock_list_get(void);
363 static int witness_lock_order_add(struct witness *parent,
364 struct witness *child);
365 static int witness_lock_order_check(struct witness *parent,
366 struct witness *child);
367 static struct witness_lock_order_data *witness_lock_order_get(
368 struct witness *parent,
369 struct witness *child);
370 static void witness_list_lock(struct lock_instance *instance,
371 int (*prnt)(const char *fmt, ...));
372 static void witness_setflag(struct lock_object *lock, int flag, int set);
375 #define witness_debugger(c) _witness_debugger(c, __func__)
377 #define witness_debugger(c)
380 SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL, "Witness Locking");
383 * If set to 0, lock order checking is disabled. If set to -1,
384 * witness is completely disabled. Otherwise witness performs full
385 * lock order checking for all locks. At runtime, lock order checking
386 * may be toggled. However, witness cannot be reenabled once it is
387 * completely disabled.
389 static int witness_watch = 1;
390 TUNABLE_INT("debug.witness.watch", &witness_watch);
391 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0,
392 sysctl_debug_witness_watch, "I", "witness is watching lock operations");
396 * When KDB is enabled and witness_kdb is 1, it will cause the system
397 * to drop into kdebug() when:
398 * - a lock hierarchy violation occurs
399 * - locks are held when going to sleep.
406 TUNABLE_INT("debug.witness.kdb", &witness_kdb);
407 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, "");
410 * When KDB is enabled and witness_trace is 1, it will cause the system
411 * to print a stack trace:
412 * - a lock hierarchy violation occurs
413 * - locks are held when going to sleep.
415 int witness_trace = 1;
416 TUNABLE_INT("debug.witness.trace", &witness_trace);
417 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, "");
420 #ifdef WITNESS_SKIPSPIN
421 int witness_skipspin = 1;
423 int witness_skipspin = 0;
425 TUNABLE_INT("debug.witness.skipspin", &witness_skipspin);
426 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin,
430 * Call this to print out the relations between locks.
432 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD,
433 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs");
436 * Call this to print out the witness faulty stacks.
438 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD,
439 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks");
441 static struct mtx w_mtx;
444 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free);
445 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all);
448 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin);
449 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep);
452 static struct lock_list_entry *w_lock_list_free = NULL;
453 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST];
454 static u_int pending_cnt;
456 static int w_free_cnt, w_spin_cnt, w_sleep_cnt;
457 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, "");
458 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, "");
459 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0,
462 static struct witness *w_data;
463 static uint8_t w_rmatrix[WITNESS_COUNT+1][WITNESS_COUNT+1];
464 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT];
465 static struct witness_hash w_hash; /* The witness hash table. */
467 /* The lock order data hash */
468 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT];
469 static struct witness_lock_order_data *w_lofree = NULL;
470 static struct witness_lock_order_hash w_lohash;
471 static int w_max_used_index = 0;
472 static unsigned int w_generation = 0;
473 static const char w_notrunning[] = "Witness not running\n";
474 static const char w_stillcold[] = "Witness is still cold\n";
477 static struct witness_order_list_entry order_lists[] = {
481 { "proctree", &lock_class_sx },
482 { "allproc", &lock_class_sx },
483 { "allprison", &lock_class_sx },
488 { "Giant", &lock_class_mtx_sleep },
489 { "pipe mutex", &lock_class_mtx_sleep },
490 { "sigio lock", &lock_class_mtx_sleep },
491 { "process group", &lock_class_mtx_sleep },
492 { "process lock", &lock_class_mtx_sleep },
493 { "session", &lock_class_mtx_sleep },
494 { "uidinfo hash", &lock_class_rw },
496 { "pmc-sleep", &lock_class_mtx_sleep },
502 { "accept", &lock_class_mtx_sleep },
503 { "so_snd", &lock_class_mtx_sleep },
504 { "so_rcv", &lock_class_mtx_sleep },
505 { "sellck", &lock_class_mtx_sleep },
510 { "so_rcv", &lock_class_mtx_sleep },
511 { "radix node head", &lock_class_rw },
512 { "rtentry", &lock_class_mtx_sleep },
513 { "ifaddr", &lock_class_mtx_sleep },
517 * protocol locks before interface locks, after UDP locks.
519 { "udpinp", &lock_class_rw },
520 { "in_multi_mtx", &lock_class_mtx_sleep },
521 { "igmp_mtx", &lock_class_mtx_sleep },
522 { "if_addr_mtx", &lock_class_mtx_sleep },
526 * protocol locks before interface locks, after UDP locks.
528 { "udpinp", &lock_class_rw },
529 { "in6_multi_mtx", &lock_class_mtx_sleep },
530 { "mld_mtx", &lock_class_mtx_sleep },
531 { "if_addr_mtx", &lock_class_mtx_sleep },
534 * UNIX Domain Sockets
536 { "unp_global_rwlock", &lock_class_rw },
537 { "unp_list_lock", &lock_class_mtx_sleep },
538 { "unp", &lock_class_mtx_sleep },
539 { "so_snd", &lock_class_mtx_sleep },
544 { "udp", &lock_class_rw },
545 { "udpinp", &lock_class_rw },
546 { "so_snd", &lock_class_mtx_sleep },
551 { "tcp", &lock_class_rw },
552 { "tcpinp", &lock_class_rw },
553 { "so_snd", &lock_class_mtx_sleep },
558 { "ddp_list_mtx", &lock_class_mtx_sleep },
559 { "ddp_mtx", &lock_class_mtx_sleep },
564 { "bpf global lock", &lock_class_mtx_sleep },
565 { "bpf interface lock", &lock_class_mtx_sleep },
566 { "bpf cdev lock", &lock_class_mtx_sleep },
571 { "nfsd_mtx", &lock_class_mtx_sleep },
572 { "so_snd", &lock_class_mtx_sleep },
578 { "802.11 com lock", &lock_class_mtx_sleep},
583 { "network driver", &lock_class_mtx_sleep},
589 { "ng_node", &lock_class_mtx_sleep },
590 { "ng_worklist", &lock_class_mtx_sleep },
595 { "system map", &lock_class_mtx_sleep },
596 { "vm page queue mutex", &lock_class_mtx_sleep },
597 { "vnode interlock", &lock_class_mtx_sleep },
598 { "cdev", &lock_class_mtx_sleep },
604 { "vm object", &lock_class_mtx_sleep },
605 { "page lock", &lock_class_mtx_sleep },
606 { "vm page queue mutex", &lock_class_mtx_sleep },
607 { "pmap", &lock_class_mtx_sleep },
610 * kqueue/VFS interaction
612 { "kqueue", &lock_class_mtx_sleep },
613 { "struct mount mtx", &lock_class_mtx_sleep },
614 { "vnode interlock", &lock_class_mtx_sleep },
619 { "dn->dn_mtx", &lock_class_sx },
620 { "dr->dt.di.dr_mtx", &lock_class_sx },
621 { "db->db_mtx", &lock_class_sx },
627 { "ap boot", &lock_class_mtx_spin },
629 { "rm.mutex_mtx", &lock_class_mtx_spin },
630 { "sio", &lock_class_mtx_spin },
631 { "scrlock", &lock_class_mtx_spin },
633 { "cy", &lock_class_mtx_spin },
636 { "pcib_mtx", &lock_class_mtx_spin },
637 { "rtc_mtx", &lock_class_mtx_spin },
639 { "scc_hwmtx", &lock_class_mtx_spin },
640 { "uart_hwmtx", &lock_class_mtx_spin },
641 { "fast_taskqueue", &lock_class_mtx_spin },
642 { "intr table", &lock_class_mtx_spin },
644 { "pmc-per-proc", &lock_class_mtx_spin },
646 { "process slock", &lock_class_mtx_spin },
647 { "sleepq chain", &lock_class_mtx_spin },
648 { "umtx lock", &lock_class_mtx_spin },
649 { "rm_spinlock", &lock_class_mtx_spin },
650 { "turnstile chain", &lock_class_mtx_spin },
651 { "turnstile lock", &lock_class_mtx_spin },
652 { "sched lock", &lock_class_mtx_spin },
653 { "td_contested", &lock_class_mtx_spin },
654 { "callout", &lock_class_mtx_spin },
655 { "entropy harvest mutex", &lock_class_mtx_spin },
656 { "syscons video lock", &lock_class_mtx_spin },
657 { "time lock", &lock_class_mtx_spin },
659 { "smp rendezvous", &lock_class_mtx_spin },
662 { "tlb0", &lock_class_mtx_spin },
667 { "intrcnt", &lock_class_mtx_spin },
668 { "icu", &lock_class_mtx_spin },
669 #if defined(SMP) && defined(__sparc64__)
670 { "ipi", &lock_class_mtx_spin },
673 { "allpmaps", &lock_class_mtx_spin },
674 { "descriptor tables", &lock_class_mtx_spin },
676 { "clk", &lock_class_mtx_spin },
677 { "cpuset", &lock_class_mtx_spin },
678 { "mprof lock", &lock_class_mtx_spin },
679 { "zombie lock", &lock_class_mtx_spin },
680 { "ALD Queue", &lock_class_mtx_spin },
682 { "MCA spin lock", &lock_class_mtx_spin },
684 #if defined(__i386__) || defined(__amd64__)
685 { "pcicfg", &lock_class_mtx_spin },
686 { "NDIS thread lock", &lock_class_mtx_spin },
688 { "tw_osl_io_lock", &lock_class_mtx_spin },
689 { "tw_osl_q_lock", &lock_class_mtx_spin },
690 { "tw_cl_io_lock", &lock_class_mtx_spin },
691 { "tw_cl_intr_lock", &lock_class_mtx_spin },
692 { "tw_cl_gen_lock", &lock_class_mtx_spin },
694 { "pmc-leaf", &lock_class_mtx_spin },
696 { "blocked lock", &lock_class_mtx_spin },
703 * Pairs of locks which have been blessed
704 * Don't complain about order problems with blessed locks
706 static struct witness_blessed blessed_list[] = {
708 static int blessed_count =
709 sizeof(blessed_list) / sizeof(struct witness_blessed);
713 * This global is set to 0 once it becomes safe to use the witness code.
715 static int witness_cold = 1;
718 * This global is set to 1 once the static lock orders have been enrolled
719 * so that a warning can be issued for any spin locks enrolled later.
721 static int witness_spin_warn = 0;
724 * The WITNESS-enabled diagnostic code. Note that the witness code does
725 * assume that the early boot is single-threaded at least until after this
726 * routine is completed.
729 witness_initialize(void *dummy __unused)
731 struct lock_object *lock;
732 struct witness_order_list_entry *order;
733 struct witness *w, *w1;
736 w_data = malloc(sizeof (struct witness) * WITNESS_COUNT, M_WITNESS,
740 * We have to release Giant before initializing its witness
741 * structure so that WITNESS doesn't get confused.
744 mtx_assert(&Giant, MA_NOTOWNED);
746 CTR1(KTR_WITNESS, "%s: initializing witness", __func__);
747 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET |
748 MTX_NOWITNESS | MTX_NOPROFILE);
749 for (i = WITNESS_COUNT - 1; i >= 0; i--) {
751 memset(w, 0, sizeof(*w));
752 w_data[i].w_index = i; /* Witness index never changes. */
755 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0,
756 ("%s: Invalid list of free witness objects", __func__));
758 /* Witness with index 0 is not used to aid in debugging. */
759 STAILQ_REMOVE_HEAD(&w_free, w_list);
763 (sizeof(**w_rmatrix) * (WITNESS_COUNT+1) * (WITNESS_COUNT+1)));
765 for (i = 0; i < LOCK_CHILDCOUNT; i++)
766 witness_lock_list_free(&w_locklistdata[i]);
767 witness_init_hash_tables();
769 /* First add in all the specified order lists. */
770 for (order = order_lists; order->w_name != NULL; order++) {
771 w = enroll(order->w_name, order->w_class);
774 w->w_file = "order list";
775 for (order++; order->w_name != NULL; order++) {
776 w1 = enroll(order->w_name, order->w_class);
779 w1->w_file = "order list";
784 witness_spin_warn = 1;
786 /* Iterate through all locks and add them to witness. */
787 for (i = 0; pending_locks[i].wh_lock != NULL; i++) {
788 lock = pending_locks[i].wh_lock;
789 KASSERT(lock->lo_flags & LO_WITNESS,
790 ("%s: lock %s is on pending list but not LO_WITNESS",
791 __func__, lock->lo_name));
792 lock->lo_witness = enroll(pending_locks[i].wh_type,
796 /* Mark the witness code as being ready for use. */
801 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize,
805 witness_init(struct lock_object *lock, const char *type)
807 struct lock_class *class;
809 /* Various sanity checks. */
810 class = LOCK_CLASS(lock);
811 if ((lock->lo_flags & LO_RECURSABLE) != 0 &&
812 (class->lc_flags & LC_RECURSABLE) == 0)
813 panic("%s: lock (%s) %s can not be recursable", __func__,
814 class->lc_name, lock->lo_name);
815 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
816 (class->lc_flags & LC_SLEEPABLE) == 0)
817 panic("%s: lock (%s) %s can not be sleepable", __func__,
818 class->lc_name, lock->lo_name);
819 if ((lock->lo_flags & LO_UPGRADABLE) != 0 &&
820 (class->lc_flags & LC_UPGRADABLE) == 0)
821 panic("%s: lock (%s) %s can not be upgradable", __func__,
822 class->lc_name, lock->lo_name);
825 * If we shouldn't watch this lock, then just clear lo_witness.
826 * Otherwise, if witness_cold is set, then it is too early to
827 * enroll this lock, so defer it to witness_initialize() by adding
828 * it to the pending_locks list. If it is not too early, then enroll
831 if (witness_watch < 1 || panicstr != NULL ||
832 (lock->lo_flags & LO_WITNESS) == 0)
833 lock->lo_witness = NULL;
834 else if (witness_cold) {
835 pending_locks[pending_cnt].wh_lock = lock;
836 pending_locks[pending_cnt++].wh_type = type;
837 if (pending_cnt > WITNESS_PENDLIST)
838 panic("%s: pending locks list is too small, bump it\n",
841 lock->lo_witness = enroll(type, class);
845 witness_destroy(struct lock_object *lock)
847 struct lock_class *class;
850 class = LOCK_CLASS(lock);
853 panic("lock (%s) %s destroyed while witness_cold",
854 class->lc_name, lock->lo_name);
856 /* XXX: need to verify that no one holds the lock */
857 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL)
859 w = lock->lo_witness;
861 mtx_lock_spin(&w_mtx);
862 MPASS(w->w_refcount > 0);
865 if (w->w_refcount == 0)
867 mtx_unlock_spin(&w_mtx);
872 witness_ddb_compute_levels(void)
877 * First clear all levels.
879 STAILQ_FOREACH(w, &w_all, w_list)
883 * Look for locks with no parents and level all their descendants.
885 STAILQ_FOREACH(w, &w_all, w_list) {
887 /* If the witness has ancestors (is not a root), skip it. */
888 if (w->w_num_ancestors > 0)
890 witness_ddb_level_descendants(w, 0);
895 witness_ddb_level_descendants(struct witness *w, int l)
899 if (w->w_ddb_level >= l)
905 for (i = 1; i <= w_max_used_index; i++) {
906 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT)
907 witness_ddb_level_descendants(&w_data[i], l);
912 witness_ddb_display_descendants(int(*prnt)(const char *fmt, ...),
913 struct witness *w, int indent)
917 for (i = 0; i < indent; i++)
919 prnt("%s (type: %s, depth: %d, active refs: %d)",
920 w->w_name, w->w_class->lc_name,
921 w->w_ddb_level, w->w_refcount);
922 if (w->w_displayed) {
923 prnt(" -- (already displayed)\n");
927 if (w->w_file != NULL && w->w_line != 0)
928 prnt(" -- last acquired @ %s:%d\n", w->w_file,
931 prnt(" -- never acquired\n");
933 WITNESS_INDEX_ASSERT(w->w_index);
934 for (i = 1; i <= w_max_used_index; i++) {
935 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT)
936 witness_ddb_display_descendants(prnt, &w_data[i],
942 witness_ddb_display_list(int(*prnt)(const char *fmt, ...),
943 struct witness_list *list)
947 STAILQ_FOREACH(w, list, w_typelist) {
948 if (w->w_file == NULL || w->w_ddb_level > 0)
951 /* This lock has no anscestors - display its descendants. */
952 witness_ddb_display_descendants(prnt, w, 0);
957 witness_ddb_display(int(*prnt)(const char *fmt, ...))
961 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
962 witness_ddb_compute_levels();
964 /* Clear all the displayed flags. */
965 STAILQ_FOREACH(w, &w_all, w_list)
969 * First, handle sleep locks which have been acquired at least
972 prnt("Sleep locks:\n");
973 witness_ddb_display_list(prnt, &w_sleep);
976 * Now do spin locks which have been acquired at least once.
978 prnt("\nSpin locks:\n");
979 witness_ddb_display_list(prnt, &w_spin);
982 * Finally, any locks which have not been acquired yet.
984 prnt("\nLocks which were never acquired:\n");
985 STAILQ_FOREACH(w, &w_all, w_list) {
986 if (w->w_file != NULL || w->w_refcount == 0)
988 prnt("%s (type: %s, depth: %d)\n", w->w_name,
989 w->w_class->lc_name, w->w_ddb_level);
994 /* Trim useless garbage from filenames. */
996 fixup_filename(const char *file)
1001 while (strncmp(file, "../", 3) == 0)
1007 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2)
1010 if (witness_watch == -1 || panicstr != NULL)
1013 /* Require locks that witness knows about. */
1014 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL ||
1015 lock2->lo_witness == NULL)
1018 mtx_assert(&w_mtx, MA_NOTOWNED);
1019 mtx_lock_spin(&w_mtx);
1022 * If we already have either an explicit or implied lock order that
1023 * is the other way around, then return an error.
1025 if (witness_watch &&
1026 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) {
1027 mtx_unlock_spin(&w_mtx);
1031 /* Try to add the new order. */
1032 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
1033 lock2->lo_witness->w_name, lock1->lo_witness->w_name);
1034 itismychild(lock1->lo_witness, lock2->lo_witness);
1035 mtx_unlock_spin(&w_mtx);
1040 witness_checkorder(struct lock_object *lock, int flags, const char *file,
1041 int line, struct lock_object *interlock)
1043 struct lock_list_entry *lock_list, *lle;
1044 struct lock_instance *lock1, *lock2, *plock;
1045 struct lock_class *class;
1046 struct witness *w, *w1;
1050 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL ||
1054 w = lock->lo_witness;
1055 class = LOCK_CLASS(lock);
1057 file = fixup_filename(file);
1059 if (class->lc_flags & LC_SLEEPLOCK) {
1062 * Since spin locks include a critical section, this check
1063 * implicitly enforces a lock order of all sleep locks before
1066 if (td->td_critnest != 0 && !kdb_active)
1067 panic("blockable sleep lock (%s) %s @ %s:%d",
1068 class->lc_name, lock->lo_name, file, line);
1071 * If this is the first lock acquired then just return as
1072 * no order checking is needed.
1074 lock_list = td->td_sleeplocks;
1075 if (lock_list == NULL || lock_list->ll_count == 0)
1080 * If this is the first lock, just return as no order
1081 * checking is needed. Avoid problems with thread
1082 * migration pinning the thread while checking if
1083 * spinlocks are held. If at least one spinlock is held
1084 * the thread is in a safe path and it is allowed to
1088 lock_list = PCPU_GET(spinlocks);
1089 if (lock_list == NULL || lock_list->ll_count == 0) {
1097 * Check to see if we are recursing on a lock we already own. If
1098 * so, make sure that we don't mismatch exclusive and shared lock
1101 lock1 = find_instance(lock_list, lock);
1102 if (lock1 != NULL) {
1103 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 &&
1104 (flags & LOP_EXCLUSIVE) == 0) {
1105 printf("shared lock of (%s) %s @ %s:%d\n",
1106 class->lc_name, lock->lo_name, file, line);
1107 printf("while exclusively locked from %s:%d\n",
1108 lock1->li_file, lock1->li_line);
1109 panic("share->excl");
1111 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 &&
1112 (flags & LOP_EXCLUSIVE) != 0) {
1113 printf("exclusive lock of (%s) %s @ %s:%d\n",
1114 class->lc_name, lock->lo_name, file, line);
1115 printf("while share locked from %s:%d\n",
1116 lock1->li_file, lock1->li_line);
1117 panic("excl->share");
1123 * Find the previously acquired lock, but ignore interlocks.
1125 plock = &lock_list->ll_children[lock_list->ll_count - 1];
1126 if (interlock != NULL && plock->li_lock == interlock) {
1127 if (lock_list->ll_count > 1)
1129 &lock_list->ll_children[lock_list->ll_count - 2];
1131 lle = lock_list->ll_next;
1134 * The interlock is the only lock we hold, so
1139 plock = &lle->ll_children[lle->ll_count - 1];
1144 * Try to perform most checks without a lock. If this succeeds we
1145 * can skip acquiring the lock and return success.
1147 w1 = plock->li_lock->lo_witness;
1148 if (witness_lock_order_check(w1, w))
1152 * Check for duplicate locks of the same type. Note that we only
1153 * have to check for this on the last lock we just acquired. Any
1154 * other cases will be caught as lock order violations.
1156 mtx_lock_spin(&w_mtx);
1157 witness_lock_order_add(w1, w);
1160 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) &&
1161 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) {
1162 w_rmatrix[i][i] |= WITNESS_REVERSAL;
1164 mtx_unlock_spin(&w_mtx);
1166 "acquiring duplicate lock of same type: \"%s\"\n",
1168 printf(" 1st %s @ %s:%d\n", plock->li_lock->lo_name,
1169 plock->li_file, plock->li_line);
1170 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line);
1171 witness_debugger(1);
1173 mtx_unlock_spin(&w_mtx);
1176 mtx_assert(&w_mtx, MA_OWNED);
1179 * If we know that the the lock we are acquiring comes after
1180 * the lock we most recently acquired in the lock order tree,
1181 * then there is no need for any further checks.
1183 if (isitmychild(w1, w))
1186 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) {
1187 for (i = lle->ll_count - 1; i >= 0; i--, j++) {
1189 MPASS(j < WITNESS_COUNT);
1190 lock1 = &lle->ll_children[i];
1193 * Ignore the interlock the first time we see it.
1195 if (interlock != NULL && interlock == lock1->li_lock) {
1201 * If this lock doesn't undergo witness checking,
1204 w1 = lock1->li_lock->lo_witness;
1206 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0,
1207 ("lock missing witness structure"));
1212 * If we are locking Giant and this is a sleepable
1213 * lock, then skip it.
1215 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 &&
1216 lock == &Giant.lock_object)
1220 * If we are locking a sleepable lock and this lock
1221 * is Giant, then skip it.
1223 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1224 lock1->li_lock == &Giant.lock_object)
1228 * If we are locking a sleepable lock and this lock
1229 * isn't sleepable, we want to treat it as a lock
1230 * order violation to enfore a general lock order of
1231 * sleepable locks before non-sleepable locks.
1233 if (((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1234 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0))
1238 * If we are locking Giant and this is a non-sleepable
1239 * lock, then treat it as a reversal.
1241 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 &&
1242 lock == &Giant.lock_object)
1246 * Check the lock order hierarchy for a reveresal.
1248 if (!isitmydescendant(w, w1))
1253 * We have a lock order violation, check to see if it
1254 * is allowed or has already been yelled about.
1259 * If the lock order is blessed, just bail. We don't
1260 * look for other lock order violations though, which
1267 /* Bail if this violation is known */
1268 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL)
1271 /* Record this as a violation */
1272 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL;
1273 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL;
1274 w->w_reversed = w1->w_reversed = 1;
1275 witness_increment_graph_generation();
1276 mtx_unlock_spin(&w_mtx);
1279 * Ok, yell about it.
1281 if (((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1282 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0))
1284 "lock order reversal: (sleepable after non-sleepable)\n");
1285 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0
1286 && lock == &Giant.lock_object)
1288 "lock order reversal: (Giant after non-sleepable)\n");
1290 printf("lock order reversal:\n");
1293 * Try to locate an earlier lock with
1294 * witness w in our list.
1297 lock2 = &lle->ll_children[i];
1298 MPASS(lock2->li_lock != NULL);
1299 if (lock2->li_lock->lo_witness == w)
1301 if (i == 0 && lle->ll_next != NULL) {
1303 i = lle->ll_count - 1;
1304 MPASS(i >= 0 && i < LOCK_NCHILDREN);
1309 printf(" 1st %p %s (%s) @ %s:%d\n",
1310 lock1->li_lock, lock1->li_lock->lo_name,
1311 w1->w_name, lock1->li_file, lock1->li_line);
1312 printf(" 2nd %p %s (%s) @ %s:%d\n", lock,
1313 lock->lo_name, w->w_name, file, line);
1315 printf(" 1st %p %s (%s) @ %s:%d\n",
1316 lock2->li_lock, lock2->li_lock->lo_name,
1317 lock2->li_lock->lo_witness->w_name,
1318 lock2->li_file, lock2->li_line);
1319 printf(" 2nd %p %s (%s) @ %s:%d\n",
1320 lock1->li_lock, lock1->li_lock->lo_name,
1321 w1->w_name, lock1->li_file, lock1->li_line);
1322 printf(" 3rd %p %s (%s) @ %s:%d\n", lock,
1323 lock->lo_name, w->w_name, file, line);
1325 witness_debugger(1);
1331 * If requested, build a new lock order. However, don't build a new
1332 * relationship between a sleepable lock and Giant if it is in the
1333 * wrong direction. The correct lock order is that sleepable locks
1334 * always come before Giant.
1336 if (flags & LOP_NEWORDER &&
1337 !(plock->li_lock == &Giant.lock_object &&
1338 (lock->lo_flags & LO_SLEEPABLE) != 0)) {
1339 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
1340 w->w_name, plock->li_lock->lo_witness->w_name);
1341 itismychild(plock->li_lock->lo_witness, w);
1344 mtx_unlock_spin(&w_mtx);
1348 witness_lock(struct lock_object *lock, int flags, const char *file, int line)
1350 struct lock_list_entry **lock_list, *lle;
1351 struct lock_instance *instance;
1355 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL ||
1358 w = lock->lo_witness;
1360 file = fixup_filename(file);
1362 /* Determine lock list for this lock. */
1363 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK)
1364 lock_list = &td->td_sleeplocks;
1366 lock_list = PCPU_PTR(spinlocks);
1368 /* Check to see if we are recursing on a lock we already own. */
1369 instance = find_instance(*lock_list, lock);
1370 if (instance != NULL) {
1371 instance->li_flags++;
1372 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__,
1373 td->td_proc->p_pid, lock->lo_name,
1374 instance->li_flags & LI_RECURSEMASK);
1375 instance->li_file = file;
1376 instance->li_line = line;
1380 /* Update per-witness last file and line acquire. */
1384 /* Find the next open lock instance in the list and fill it. */
1386 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) {
1387 lle = witness_lock_list_get();
1390 lle->ll_next = *lock_list;
1391 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__,
1392 td->td_proc->p_pid, lle);
1395 instance = &lle->ll_children[lle->ll_count++];
1396 instance->li_lock = lock;
1397 instance->li_line = line;
1398 instance->li_file = file;
1399 if ((flags & LOP_EXCLUSIVE) != 0)
1400 instance->li_flags = LI_EXCLUSIVE;
1402 instance->li_flags = 0;
1403 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__,
1404 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1);
1408 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line)
1410 struct lock_instance *instance;
1411 struct lock_class *class;
1413 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1414 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
1416 class = LOCK_CLASS(lock);
1417 file = fixup_filename(file);
1418 if (witness_watch) {
1419 if ((lock->lo_flags & LO_UPGRADABLE) == 0)
1420 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d",
1421 class->lc_name, lock->lo_name, file, line);
1422 if ((class->lc_flags & LC_SLEEPLOCK) == 0)
1423 panic("upgrade of non-sleep lock (%s) %s @ %s:%d",
1424 class->lc_name, lock->lo_name, file, line);
1426 instance = find_instance(curthread->td_sleeplocks, lock);
1427 if (instance == NULL)
1428 panic("upgrade of unlocked lock (%s) %s @ %s:%d",
1429 class->lc_name, lock->lo_name, file, line);
1430 if (witness_watch) {
1431 if ((instance->li_flags & LI_EXCLUSIVE) != 0)
1432 panic("upgrade of exclusive lock (%s) %s @ %s:%d",
1433 class->lc_name, lock->lo_name, file, line);
1434 if ((instance->li_flags & LI_RECURSEMASK) != 0)
1435 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d",
1436 class->lc_name, lock->lo_name,
1437 instance->li_flags & LI_RECURSEMASK, file, line);
1439 instance->li_flags |= LI_EXCLUSIVE;
1443 witness_downgrade(struct lock_object *lock, int flags, const char *file,
1446 struct lock_instance *instance;
1447 struct lock_class *class;
1449 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1450 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
1452 class = LOCK_CLASS(lock);
1453 file = fixup_filename(file);
1454 if (witness_watch) {
1455 if ((lock->lo_flags & LO_UPGRADABLE) == 0)
1456 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d",
1457 class->lc_name, lock->lo_name, file, line);
1458 if ((class->lc_flags & LC_SLEEPLOCK) == 0)
1459 panic("downgrade of non-sleep lock (%s) %s @ %s:%d",
1460 class->lc_name, lock->lo_name, file, line);
1462 instance = find_instance(curthread->td_sleeplocks, lock);
1463 if (instance == NULL)
1464 panic("downgrade of unlocked lock (%s) %s @ %s:%d",
1465 class->lc_name, lock->lo_name, file, line);
1466 if (witness_watch) {
1467 if ((instance->li_flags & LI_EXCLUSIVE) == 0)
1468 panic("downgrade of shared lock (%s) %s @ %s:%d",
1469 class->lc_name, lock->lo_name, file, line);
1470 if ((instance->li_flags & LI_RECURSEMASK) != 0)
1471 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d",
1472 class->lc_name, lock->lo_name,
1473 instance->li_flags & LI_RECURSEMASK, file, line);
1475 instance->li_flags &= ~LI_EXCLUSIVE;
1479 witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
1481 struct lock_list_entry **lock_list, *lle;
1482 struct lock_instance *instance;
1483 struct lock_class *class;
1488 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL)
1491 class = LOCK_CLASS(lock);
1492 file = fixup_filename(file);
1494 /* Find lock instance associated with this lock. */
1495 if (class->lc_flags & LC_SLEEPLOCK)
1496 lock_list = &td->td_sleeplocks;
1498 lock_list = PCPU_PTR(spinlocks);
1500 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next)
1501 for (i = 0; i < (*lock_list)->ll_count; i++) {
1502 instance = &(*lock_list)->ll_children[i];
1503 if (instance->li_lock == lock)
1508 * When disabling WITNESS through witness_watch we could end up in
1509 * having registered locks in the td_sleeplocks queue.
1510 * We have to make sure we flush these queues, so just search for
1511 * eventual register locks and remove them.
1513 if (witness_watch > 0)
1514 panic("lock (%s) %s not locked @ %s:%d", class->lc_name,
1515 lock->lo_name, file, line);
1520 /* First, check for shared/exclusive mismatches. */
1521 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 &&
1522 (flags & LOP_EXCLUSIVE) == 0) {
1523 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name,
1524 lock->lo_name, file, line);
1525 printf("while exclusively locked from %s:%d\n",
1526 instance->li_file, instance->li_line);
1527 panic("excl->ushare");
1529 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 &&
1530 (flags & LOP_EXCLUSIVE) != 0) {
1531 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name,
1532 lock->lo_name, file, line);
1533 printf("while share locked from %s:%d\n", instance->li_file,
1535 panic("share->uexcl");
1537 /* If we are recursed, unrecurse. */
1538 if ((instance->li_flags & LI_RECURSEMASK) > 0) {
1539 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__,
1540 td->td_proc->p_pid, instance->li_lock->lo_name,
1541 instance->li_flags);
1542 instance->li_flags--;
1545 /* The lock is now being dropped, check for NORELEASE flag */
1546 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) {
1547 printf("forbidden unlock of (%s) %s @ %s:%d\n", class->lc_name,
1548 lock->lo_name, file, line);
1549 panic("lock marked norelease");
1552 /* Otherwise, remove this item from the list. */
1554 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__,
1555 td->td_proc->p_pid, instance->li_lock->lo_name,
1556 (*lock_list)->ll_count - 1);
1557 for (j = i; j < (*lock_list)->ll_count - 1; j++)
1558 (*lock_list)->ll_children[j] =
1559 (*lock_list)->ll_children[j + 1];
1560 (*lock_list)->ll_count--;
1564 * In order to reduce contention on w_mtx, we want to keep always an
1565 * head object into lists so that frequent allocation from the
1566 * free witness pool (and subsequent locking) is avoided.
1567 * In order to maintain the current code simple, when the head
1568 * object is totally unloaded it means also that we do not have
1569 * further objects in the list, so the list ownership needs to be
1570 * hand over to another object if the current head needs to be freed.
1572 if ((*lock_list)->ll_count == 0) {
1573 if (*lock_list == lle) {
1574 if (lle->ll_next == NULL)
1578 *lock_list = lle->ll_next;
1579 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__,
1580 td->td_proc->p_pid, lle);
1581 witness_lock_list_free(lle);
1586 witness_thread_exit(struct thread *td)
1588 struct lock_list_entry *lle;
1591 lle = td->td_sleeplocks;
1592 if (lle == NULL || panicstr != NULL)
1594 if (lle->ll_count != 0) {
1595 for (n = 0; lle != NULL; lle = lle->ll_next)
1596 for (i = lle->ll_count - 1; i >= 0; i--) {
1598 printf("Thread %p exiting with the following locks held:\n",
1601 witness_list_lock(&lle->ll_children[i], printf);
1604 panic("Thread %p cannot exit while holding sleeplocks\n", td);
1606 witness_lock_list_free(lle);
1610 * Warn if any locks other than 'lock' are held. Flags can be passed in to
1611 * exempt Giant and sleepable locks from the checks as well. If any
1612 * non-exempt locks are held, then a supplied message is printed to the
1613 * console along with a list of the offending locks. If indicated in the
1614 * flags then a failure results in a panic as well.
1617 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...)
1619 struct lock_list_entry *lock_list, *lle;
1620 struct lock_instance *lock1;
1625 if (witness_cold || witness_watch < 1 || panicstr != NULL)
1629 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next)
1630 for (i = lle->ll_count - 1; i >= 0; i--) {
1631 lock1 = &lle->ll_children[i];
1632 if (lock1->li_lock == lock)
1634 if (flags & WARN_GIANTOK &&
1635 lock1->li_lock == &Giant.lock_object)
1637 if (flags & WARN_SLEEPOK &&
1638 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0)
1644 printf(" with the following");
1645 if (flags & WARN_SLEEPOK)
1646 printf(" non-sleepable");
1647 printf(" locks held:\n");
1650 witness_list_lock(lock1, printf);
1654 * Pin the thread in order to avoid problems with thread migration.
1655 * Once that all verifies are passed about spinlocks ownership,
1656 * the thread is in a safe path and it can be unpinned.
1659 lock_list = PCPU_GET(spinlocks);
1660 if (lock_list != NULL && lock_list->ll_count != 0) {
1664 * We should only have one spinlock and as long as
1665 * the flags cannot match for this locks class,
1666 * check if the first spinlock is the one curthread
1669 lock1 = &lock_list->ll_children[lock_list->ll_count - 1];
1670 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL &&
1671 lock1->li_lock == lock && n == 0)
1677 printf(" with the following");
1678 if (flags & WARN_SLEEPOK)
1679 printf(" non-sleepable");
1680 printf(" locks held:\n");
1681 n += witness_list_locks(&lock_list, printf);
1684 if (flags & WARN_PANIC && n)
1685 panic("%s", __func__);
1687 witness_debugger(n);
1692 witness_file(struct lock_object *lock)
1696 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
1698 w = lock->lo_witness;
1703 witness_line(struct lock_object *lock)
1707 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
1709 w = lock->lo_witness;
1713 static struct witness *
1714 enroll(const char *description, struct lock_class *lock_class)
1717 struct witness_list *typelist;
1719 MPASS(description != NULL);
1721 if (witness_watch == -1 || panicstr != NULL)
1723 if ((lock_class->lc_flags & LC_SPINLOCK)) {
1724 if (witness_skipspin)
1728 } else if ((lock_class->lc_flags & LC_SLEEPLOCK))
1729 typelist = &w_sleep;
1731 panic("lock class %s is not sleep or spin",
1732 lock_class->lc_name);
1734 mtx_lock_spin(&w_mtx);
1735 w = witness_hash_get(description);
1738 if ((w = witness_get()) == NULL)
1740 MPASS(strlen(description) < MAX_W_NAME);
1741 strcpy(w->w_name, description);
1742 w->w_class = lock_class;
1744 STAILQ_INSERT_HEAD(&w_all, w, w_list);
1745 if (lock_class->lc_flags & LC_SPINLOCK) {
1746 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist);
1748 } else if (lock_class->lc_flags & LC_SLEEPLOCK) {
1749 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist);
1753 /* Insert new witness into the hash */
1754 witness_hash_put(w);
1755 witness_increment_graph_generation();
1756 mtx_unlock_spin(&w_mtx);
1760 mtx_unlock_spin(&w_mtx);
1761 if (lock_class != w->w_class)
1763 "lock (%s) %s does not match earlier (%s) lock",
1764 description, lock_class->lc_name,
1765 w->w_class->lc_name);
1770 depart(struct witness *w)
1772 struct witness_list *list;
1774 MPASS(w->w_refcount == 0);
1775 if (w->w_class->lc_flags & LC_SLEEPLOCK) {
1783 * Set file to NULL as it may point into a loadable module.
1787 witness_increment_graph_generation();
1792 adopt(struct witness *parent, struct witness *child)
1796 if (witness_cold == 0)
1797 mtx_assert(&w_mtx, MA_OWNED);
1799 /* If the relationship is already known, there's no work to be done. */
1800 if (isitmychild(parent, child))
1803 /* When the structure of the graph changes, bump up the generation. */
1804 witness_increment_graph_generation();
1807 * The hard part ... create the direct relationship, then propagate all
1808 * indirect relationships.
1810 pi = parent->w_index;
1811 ci = child->w_index;
1812 WITNESS_INDEX_ASSERT(pi);
1813 WITNESS_INDEX_ASSERT(ci);
1815 w_rmatrix[pi][ci] |= WITNESS_PARENT;
1816 w_rmatrix[ci][pi] |= WITNESS_CHILD;
1819 * If parent was not already an ancestor of child,
1820 * then we increment the descendant and ancestor counters.
1822 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) {
1823 parent->w_num_descendants++;
1824 child->w_num_ancestors++;
1828 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as
1829 * an ancestor of 'pi' during this loop.
1831 for (i = 1; i <= w_max_used_index; i++) {
1832 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 &&
1836 /* Find each descendant of 'i' and mark it as a descendant. */
1837 for (j = 1; j <= w_max_used_index; j++) {
1840 * Skip children that are already marked as
1841 * descendants of 'i'.
1843 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK)
1847 * We are only interested in descendants of 'ci'. Note
1848 * that 'ci' itself is counted as a descendant of 'ci'.
1850 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 &&
1853 w_rmatrix[i][j] |= WITNESS_ANCESTOR;
1854 w_rmatrix[j][i] |= WITNESS_DESCENDANT;
1855 w_data[i].w_num_descendants++;
1856 w_data[j].w_num_ancestors++;
1859 * Make sure we aren't marking a node as both an
1860 * ancestor and descendant. We should have caught
1861 * this as a lock order reversal earlier.
1863 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) &&
1864 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) {
1865 printf("witness rmatrix paradox! [%d][%d]=%d "
1866 "both ancestor and descendant\n",
1867 i, j, w_rmatrix[i][j]);
1869 printf("Witness disabled.\n");
1872 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) &&
1873 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) {
1874 printf("witness rmatrix paradox! [%d][%d]=%d "
1875 "both ancestor and descendant\n",
1876 j, i, w_rmatrix[j][i]);
1878 printf("Witness disabled.\n");
1886 itismychild(struct witness *parent, struct witness *child)
1889 MPASS(child != NULL && parent != NULL);
1890 if (witness_cold == 0)
1891 mtx_assert(&w_mtx, MA_OWNED);
1893 if (!witness_lock_type_equal(parent, child)) {
1894 if (witness_cold == 0)
1895 mtx_unlock_spin(&w_mtx);
1896 panic("%s: parent \"%s\" (%s) and child \"%s\" (%s) are not "
1897 "the same lock type", __func__, parent->w_name,
1898 parent->w_class->lc_name, child->w_name,
1899 child->w_class->lc_name);
1901 adopt(parent, child);
1905 * Generic code for the isitmy*() functions. The rmask parameter is the
1906 * expected relationship of w1 to w2.
1909 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname)
1911 unsigned char r1, r2;
1916 WITNESS_INDEX_ASSERT(i1);
1917 WITNESS_INDEX_ASSERT(i2);
1918 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK;
1919 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK;
1921 /* The flags on one better be the inverse of the flags on the other */
1922 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) ||
1923 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) {
1924 printf("%s: rmatrix mismatch between %s (index %d) and %s "
1925 "(index %d): w_rmatrix[%d][%d] == %hhx but "
1926 "w_rmatrix[%d][%d] == %hhx\n",
1927 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1,
1930 printf("Witness disabled.\n");
1933 return (r1 & rmask);
1937 * Checks if @child is a direct child of @parent.
1940 isitmychild(struct witness *parent, struct witness *child)
1943 return (_isitmyx(parent, child, WITNESS_PARENT, __func__));
1947 * Checks if @descendant is a direct or inderect descendant of @ancestor.
1950 isitmydescendant(struct witness *ancestor, struct witness *descendant)
1953 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK,
1959 blessed(struct witness *w1, struct witness *w2)
1962 struct witness_blessed *b;
1964 for (i = 0; i < blessed_count; i++) {
1965 b = &blessed_list[i];
1966 if (strcmp(w1->w_name, b->b_lock1) == 0) {
1967 if (strcmp(w2->w_name, b->b_lock2) == 0)
1971 if (strcmp(w1->w_name, b->b_lock2) == 0)
1972 if (strcmp(w2->w_name, b->b_lock1) == 0)
1979 static struct witness *
1985 if (witness_cold == 0)
1986 mtx_assert(&w_mtx, MA_OWNED);
1988 if (witness_watch == -1) {
1989 mtx_unlock_spin(&w_mtx);
1992 if (STAILQ_EMPTY(&w_free)) {
1994 mtx_unlock_spin(&w_mtx);
1995 printf("WITNESS: unable to allocate a new witness object\n");
1998 w = STAILQ_FIRST(&w_free);
1999 STAILQ_REMOVE_HEAD(&w_free, w_list);
2002 MPASS(index > 0 && index == w_max_used_index+1 &&
2003 index < WITNESS_COUNT);
2004 bzero(w, sizeof(*w));
2006 if (index > w_max_used_index)
2007 w_max_used_index = index;
2012 witness_free(struct witness *w)
2015 STAILQ_INSERT_HEAD(&w_free, w, w_list);
2019 static struct lock_list_entry *
2020 witness_lock_list_get(void)
2022 struct lock_list_entry *lle;
2024 if (witness_watch == -1)
2026 mtx_lock_spin(&w_mtx);
2027 lle = w_lock_list_free;
2030 mtx_unlock_spin(&w_mtx);
2031 printf("%s: witness exhausted\n", __func__);
2034 w_lock_list_free = lle->ll_next;
2035 mtx_unlock_spin(&w_mtx);
2036 bzero(lle, sizeof(*lle));
2041 witness_lock_list_free(struct lock_list_entry *lle)
2044 mtx_lock_spin(&w_mtx);
2045 lle->ll_next = w_lock_list_free;
2046 w_lock_list_free = lle;
2047 mtx_unlock_spin(&w_mtx);
2050 static struct lock_instance *
2051 find_instance(struct lock_list_entry *list, struct lock_object *lock)
2053 struct lock_list_entry *lle;
2054 struct lock_instance *instance;
2057 for (lle = list; lle != NULL; lle = lle->ll_next)
2058 for (i = lle->ll_count - 1; i >= 0; i--) {
2059 instance = &lle->ll_children[i];
2060 if (instance->li_lock == lock)
2067 witness_list_lock(struct lock_instance *instance,
2068 int (*prnt)(const char *fmt, ...))
2070 struct lock_object *lock;
2072 lock = instance->li_lock;
2073 prnt("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ?
2074 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name);
2075 if (lock->lo_witness->w_name != lock->lo_name)
2076 prnt(" (%s)", lock->lo_witness->w_name);
2077 prnt(" r = %d (%p) locked @ %s:%d\n",
2078 instance->li_flags & LI_RECURSEMASK, lock, instance->li_file,
2084 witness_thread_has_locks(struct thread *td)
2087 if (td->td_sleeplocks == NULL)
2089 return (td->td_sleeplocks->ll_count != 0);
2093 witness_proc_has_locks(struct proc *p)
2097 FOREACH_THREAD_IN_PROC(p, td) {
2098 if (witness_thread_has_locks(td))
2106 witness_list_locks(struct lock_list_entry **lock_list,
2107 int (*prnt)(const char *fmt, ...))
2109 struct lock_list_entry *lle;
2113 for (lle = *lock_list; lle != NULL; lle = lle->ll_next)
2114 for (i = lle->ll_count - 1; i >= 0; i--) {
2115 witness_list_lock(&lle->ll_children[i], prnt);
2122 * This is a bit risky at best. We call this function when we have timed
2123 * out acquiring a spin lock, and we assume that the other CPU is stuck
2124 * with this lock held. So, we go groveling around in the other CPU's
2125 * per-cpu data to try to find the lock instance for this spin lock to
2126 * see when it was last acquired.
2129 witness_display_spinlock(struct lock_object *lock, struct thread *owner,
2130 int (*prnt)(const char *fmt, ...))
2132 struct lock_instance *instance;
2135 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU)
2137 pc = pcpu_find(owner->td_oncpu);
2138 instance = find_instance(pc->pc_spinlocks, lock);
2139 if (instance != NULL)
2140 witness_list_lock(instance, prnt);
2144 witness_save(struct lock_object *lock, const char **filep, int *linep)
2146 struct lock_list_entry *lock_list;
2147 struct lock_instance *instance;
2148 struct lock_class *class;
2150 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2151 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2153 class = LOCK_CLASS(lock);
2154 if (class->lc_flags & LC_SLEEPLOCK)
2155 lock_list = curthread->td_sleeplocks;
2157 if (witness_skipspin)
2159 lock_list = PCPU_GET(spinlocks);
2161 instance = find_instance(lock_list, lock);
2162 if (instance == NULL)
2163 panic("%s: lock (%s) %s not locked", __func__,
2164 class->lc_name, lock->lo_name);
2165 *filep = instance->li_file;
2166 *linep = instance->li_line;
2170 witness_restore(struct lock_object *lock, const char *file, int line)
2172 struct lock_list_entry *lock_list;
2173 struct lock_instance *instance;
2174 struct lock_class *class;
2176 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2177 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2179 class = LOCK_CLASS(lock);
2180 if (class->lc_flags & LC_SLEEPLOCK)
2181 lock_list = curthread->td_sleeplocks;
2183 if (witness_skipspin)
2185 lock_list = PCPU_GET(spinlocks);
2187 instance = find_instance(lock_list, lock);
2188 if (instance == NULL)
2189 panic("%s: lock (%s) %s not locked", __func__,
2190 class->lc_name, lock->lo_name);
2191 lock->lo_witness->w_file = file;
2192 lock->lo_witness->w_line = line;
2193 instance->li_file = file;
2194 instance->li_line = line;
2198 witness_assert(struct lock_object *lock, int flags, const char *file, int line)
2200 #ifdef INVARIANT_SUPPORT
2201 struct lock_instance *instance;
2202 struct lock_class *class;
2204 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL)
2206 class = LOCK_CLASS(lock);
2207 if ((class->lc_flags & LC_SLEEPLOCK) != 0)
2208 instance = find_instance(curthread->td_sleeplocks, lock);
2209 else if ((class->lc_flags & LC_SPINLOCK) != 0)
2210 instance = find_instance(PCPU_GET(spinlocks), lock);
2212 panic("Lock (%s) %s is not sleep or spin!",
2213 class->lc_name, lock->lo_name);
2215 file = fixup_filename(file);
2218 if (instance != NULL)
2219 panic("Lock (%s) %s locked @ %s:%d.",
2220 class->lc_name, lock->lo_name, file, line);
2223 case LA_LOCKED | LA_RECURSED:
2224 case LA_LOCKED | LA_NOTRECURSED:
2226 case LA_SLOCKED | LA_RECURSED:
2227 case LA_SLOCKED | LA_NOTRECURSED:
2229 case LA_XLOCKED | LA_RECURSED:
2230 case LA_XLOCKED | LA_NOTRECURSED:
2231 if (instance == NULL) {
2232 panic("Lock (%s) %s not locked @ %s:%d.",
2233 class->lc_name, lock->lo_name, file, line);
2236 if ((flags & LA_XLOCKED) != 0 &&
2237 (instance->li_flags & LI_EXCLUSIVE) == 0)
2238 panic("Lock (%s) %s not exclusively locked @ %s:%d.",
2239 class->lc_name, lock->lo_name, file, line);
2240 if ((flags & LA_SLOCKED) != 0 &&
2241 (instance->li_flags & LI_EXCLUSIVE) != 0)
2242 panic("Lock (%s) %s exclusively locked @ %s:%d.",
2243 class->lc_name, lock->lo_name, file, line);
2244 if ((flags & LA_RECURSED) != 0 &&
2245 (instance->li_flags & LI_RECURSEMASK) == 0)
2246 panic("Lock (%s) %s not recursed @ %s:%d.",
2247 class->lc_name, lock->lo_name, file, line);
2248 if ((flags & LA_NOTRECURSED) != 0 &&
2249 (instance->li_flags & LI_RECURSEMASK) != 0)
2250 panic("Lock (%s) %s recursed @ %s:%d.",
2251 class->lc_name, lock->lo_name, file, line);
2254 panic("Invalid lock assertion at %s:%d.", file, line);
2257 #endif /* INVARIANT_SUPPORT */
2261 witness_setflag(struct lock_object *lock, int flag, int set)
2263 struct lock_list_entry *lock_list;
2264 struct lock_instance *instance;
2265 struct lock_class *class;
2267 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2269 class = LOCK_CLASS(lock);
2270 if (class->lc_flags & LC_SLEEPLOCK)
2271 lock_list = curthread->td_sleeplocks;
2273 if (witness_skipspin)
2275 lock_list = PCPU_GET(spinlocks);
2277 instance = find_instance(lock_list, lock);
2278 if (instance == NULL)
2279 panic("%s: lock (%s) %s not locked", __func__,
2280 class->lc_name, lock->lo_name);
2283 instance->li_flags |= flag;
2285 instance->li_flags &= ~flag;
2289 witness_norelease(struct lock_object *lock)
2292 witness_setflag(lock, LI_NORELEASE, 1);
2296 witness_releaseok(struct lock_object *lock)
2299 witness_setflag(lock, LI_NORELEASE, 0);
2304 witness_ddb_list(struct thread *td)
2307 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2308 KASSERT(kdb_active, ("%s: not in the debugger", __func__));
2310 if (witness_watch < 1)
2313 witness_list_locks(&td->td_sleeplocks, db_printf);
2316 * We only handle spinlocks if td == curthread. This is somewhat broken
2317 * if td is currently executing on some other CPU and holds spin locks
2318 * as we won't display those locks. If we had a MI way of getting
2319 * the per-cpu data for a given cpu then we could use
2320 * td->td_oncpu to get the list of spinlocks for this thread
2323 * That still wouldn't really fix this unless we locked the scheduler
2324 * lock or stopped the other CPU to make sure it wasn't changing the
2325 * list out from under us. It is probably best to just not try to
2326 * handle threads on other CPU's for now.
2328 if (td == curthread && PCPU_GET(spinlocks) != NULL)
2329 witness_list_locks(PCPU_PTR(spinlocks), db_printf);
2332 DB_SHOW_COMMAND(locks, db_witness_list)
2337 td = db_lookup_thread(addr, TRUE);
2340 witness_ddb_list(td);
2343 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all)
2349 * It would be nice to list only threads and processes that actually
2350 * held sleep locks, but that information is currently not exported
2353 FOREACH_PROC_IN_SYSTEM(p) {
2354 if (!witness_proc_has_locks(p))
2356 FOREACH_THREAD_IN_PROC(p, td) {
2357 if (!witness_thread_has_locks(td))
2359 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid,
2360 p->p_comm, td, td->td_tid);
2361 witness_ddb_list(td);
2365 DB_SHOW_ALIAS(alllocks, db_witness_list_all)
2367 DB_SHOW_COMMAND(witness, db_witness_display)
2370 witness_ddb_display(db_printf);
2375 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS)
2377 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2;
2378 struct witness *tmp_w1, *tmp_w2, *w1, *w2;
2380 u_int w_rmatrix1, w_rmatrix2;
2381 int error, generation, i, j;
2387 if (witness_watch < 1) {
2388 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
2392 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
2396 sb = sbuf_new(NULL, NULL, BADSTACK_SBUF_SIZE, SBUF_AUTOEXTEND);
2400 /* Allocate and init temporary storage space. */
2401 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
2402 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
2403 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP,
2405 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP,
2407 stack_zero(&tmp_data1->wlod_stack);
2408 stack_zero(&tmp_data2->wlod_stack);
2411 mtx_lock_spin(&w_mtx);
2412 generation = w_generation;
2413 mtx_unlock_spin(&w_mtx);
2414 sbuf_printf(sb, "Number of known direct relationships is %d\n",
2415 w_lohash.wloh_count);
2416 for (i = 1; i < w_max_used_index; i++) {
2417 mtx_lock_spin(&w_mtx);
2418 if (generation != w_generation) {
2419 mtx_unlock_spin(&w_mtx);
2421 /* The graph has changed, try again. */
2428 if (w1->w_reversed == 0) {
2429 mtx_unlock_spin(&w_mtx);
2433 /* Copy w1 locally so we can release the spin lock. */
2435 mtx_unlock_spin(&w_mtx);
2437 if (tmp_w1->w_reversed == 0)
2439 for (j = 1; j < w_max_used_index; j++) {
2440 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j)
2443 mtx_lock_spin(&w_mtx);
2444 if (generation != w_generation) {
2445 mtx_unlock_spin(&w_mtx);
2447 /* The graph has changed, try again. */
2454 data1 = witness_lock_order_get(w1, w2);
2455 data2 = witness_lock_order_get(w2, w1);
2458 * Copy information locally so we can release the
2462 w_rmatrix1 = (unsigned int)w_rmatrix[i][j];
2463 w_rmatrix2 = (unsigned int)w_rmatrix[j][i];
2466 stack_zero(&tmp_data1->wlod_stack);
2467 stack_copy(&data1->wlod_stack,
2468 &tmp_data1->wlod_stack);
2470 if (data2 && data2 != data1) {
2471 stack_zero(&tmp_data2->wlod_stack);
2472 stack_copy(&data2->wlod_stack,
2473 &tmp_data2->wlod_stack);
2475 mtx_unlock_spin(&w_mtx);
2478 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n",
2479 tmp_w1->w_name, tmp_w1->w_class->lc_name,
2480 tmp_w2->w_name, tmp_w2->w_class->lc_name);
2483 "w_rmatrix[%s][%s] == %x, w_rmatrix[%s][%s] == %x\n",
2484 tmp_w1->name, tmp_w2->w_name, w_rmatrix1,
2485 tmp_w2->name, tmp_w1->w_name, w_rmatrix2);
2489 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
2490 tmp_w1->w_name, tmp_w1->w_class->lc_name,
2491 tmp_w2->w_name, tmp_w2->w_class->lc_name);
2492 stack_sbuf_print(sb, &tmp_data1->wlod_stack);
2493 sbuf_printf(sb, "\n");
2495 if (data2 && data2 != data1) {
2497 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
2498 tmp_w2->w_name, tmp_w2->w_class->lc_name,
2499 tmp_w1->w_name, tmp_w1->w_class->lc_name);
2500 stack_sbuf_print(sb, &tmp_data2->wlod_stack);
2501 sbuf_printf(sb, "\n");
2505 mtx_lock_spin(&w_mtx);
2506 if (generation != w_generation) {
2507 mtx_unlock_spin(&w_mtx);
2510 * The graph changed while we were printing stack data,
2517 mtx_unlock_spin(&w_mtx);
2519 /* Free temporary storage space. */
2520 free(tmp_data1, M_TEMP);
2521 free(tmp_data2, M_TEMP);
2522 free(tmp_w1, M_TEMP);
2523 free(tmp_w2, M_TEMP);
2526 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
2533 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS)
2539 if (witness_watch < 1) {
2540 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
2544 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
2548 sb = sbuf_new(NULL, NULL, FULLGRAPH_SBUF_SIZE, SBUF_FIXEDLEN);
2551 sbuf_printf(sb, "\n");
2553 mtx_lock_spin(&w_mtx);
2554 STAILQ_FOREACH(w, &w_all, w_list)
2556 STAILQ_FOREACH(w, &w_all, w_list)
2557 witness_add_fullgraph(sb, w);
2558 mtx_unlock_spin(&w_mtx);
2561 * While using SBUF_FIXEDLEN, check if the sbuf overflowed.
2563 if (sbuf_overflowed(sb)) {
2565 panic("%s: sbuf overflowed, bump FULLGRAPH_SBUF_SIZE value\n",
2570 * Close the sbuf and return to userland.
2573 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
2580 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS)
2584 value = witness_watch;
2585 error = sysctl_handle_int(oidp, &value, 0, req);
2586 if (error != 0 || req->newptr == NULL)
2588 if (value > 1 || value < -1 ||
2589 (witness_watch == -1 && value != witness_watch))
2591 witness_watch = value;
2596 witness_add_fullgraph(struct sbuf *sb, struct witness *w)
2600 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0))
2604 WITNESS_INDEX_ASSERT(w->w_index);
2605 for (i = 1; i <= w_max_used_index; i++) {
2606 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) {
2607 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name,
2609 witness_add_fullgraph(sb, &w_data[i]);
2615 * A simple hash function. Takes a key pointer and a key size. If size == 0,
2616 * interprets the key as a string and reads until the null
2617 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit
2618 * hash value computed from the key.
2621 witness_hash_djb2(const uint8_t *key, uint32_t size)
2623 unsigned int hash = 5381;
2626 /* hash = hash * 33 + key[i] */
2628 for (i = 0; i < size; i++)
2629 hash = ((hash << 5) + hash) + (unsigned int)key[i];
2631 for (i = 0; key[i] != 0; i++)
2632 hash = ((hash << 5) + hash) + (unsigned int)key[i];
2639 * Initializes the two witness hash tables. Called exactly once from
2640 * witness_initialize().
2643 witness_init_hash_tables(void)
2647 MPASS(witness_cold);
2649 /* Initialize the hash tables. */
2650 for (i = 0; i < WITNESS_HASH_SIZE; i++)
2651 w_hash.wh_array[i] = NULL;
2653 w_hash.wh_size = WITNESS_HASH_SIZE;
2654 w_hash.wh_count = 0;
2656 /* Initialize the lock order data hash. */
2658 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) {
2659 memset(&w_lodata[i], 0, sizeof(w_lodata[i]));
2660 w_lodata[i].wlod_next = w_lofree;
2661 w_lofree = &w_lodata[i];
2663 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE;
2664 w_lohash.wloh_count = 0;
2665 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++)
2666 w_lohash.wloh_array[i] = NULL;
2669 static struct witness *
2670 witness_hash_get(const char *key)
2676 if (witness_cold == 0)
2677 mtx_assert(&w_mtx, MA_OWNED);
2678 hash = witness_hash_djb2(key, 0) % w_hash.wh_size;
2679 w = w_hash.wh_array[hash];
2681 if (strcmp(w->w_name, key) == 0)
2691 witness_hash_put(struct witness *w)
2696 MPASS(w->w_name != NULL);
2697 if (witness_cold == 0)
2698 mtx_assert(&w_mtx, MA_OWNED);
2699 KASSERT(witness_hash_get(w->w_name) == NULL,
2700 ("%s: trying to add a hash entry that already exists!", __func__));
2701 KASSERT(w->w_hash_next == NULL,
2702 ("%s: w->w_hash_next != NULL", __func__));
2704 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size;
2705 w->w_hash_next = w_hash.wh_array[hash];
2706 w_hash.wh_array[hash] = w;
2711 static struct witness_lock_order_data *
2712 witness_lock_order_get(struct witness *parent, struct witness *child)
2714 struct witness_lock_order_data *data = NULL;
2715 struct witness_lock_order_key key;
2718 MPASS(parent != NULL && child != NULL);
2719 key.from = parent->w_index;
2720 key.to = child->w_index;
2721 WITNESS_INDEX_ASSERT(key.from);
2722 WITNESS_INDEX_ASSERT(key.to);
2723 if ((w_rmatrix[parent->w_index][child->w_index]
2724 & WITNESS_LOCK_ORDER_KNOWN) == 0)
2727 hash = witness_hash_djb2((const char*)&key,
2728 sizeof(key)) % w_lohash.wloh_size;
2729 data = w_lohash.wloh_array[hash];
2730 while (data != NULL) {
2731 if (witness_lock_order_key_equal(&data->wlod_key, &key))
2733 data = data->wlod_next;
2741 * Verify that parent and child have a known relationship, are not the same,
2742 * and child is actually a child of parent. This is done without w_mtx
2743 * to avoid contention in the common case.
2746 witness_lock_order_check(struct witness *parent, struct witness *child)
2749 if (parent != child &&
2750 w_rmatrix[parent->w_index][child->w_index]
2751 & WITNESS_LOCK_ORDER_KNOWN &&
2752 isitmychild(parent, child))
2759 witness_lock_order_add(struct witness *parent, struct witness *child)
2761 struct witness_lock_order_data *data = NULL;
2762 struct witness_lock_order_key key;
2765 MPASS(parent != NULL && child != NULL);
2766 key.from = parent->w_index;
2767 key.to = child->w_index;
2768 WITNESS_INDEX_ASSERT(key.from);
2769 WITNESS_INDEX_ASSERT(key.to);
2770 if (w_rmatrix[parent->w_index][child->w_index]
2771 & WITNESS_LOCK_ORDER_KNOWN)
2774 hash = witness_hash_djb2((const char*)&key,
2775 sizeof(key)) % w_lohash.wloh_size;
2776 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN;
2780 w_lofree = data->wlod_next;
2781 data->wlod_next = w_lohash.wloh_array[hash];
2782 data->wlod_key = key;
2783 w_lohash.wloh_array[hash] = data;
2784 w_lohash.wloh_count++;
2785 stack_zero(&data->wlod_stack);
2786 stack_save(&data->wlod_stack);
2790 /* Call this whenver the structure of the witness graph changes. */
2792 witness_increment_graph_generation(void)
2795 if (witness_cold == 0)
2796 mtx_assert(&w_mtx, MA_OWNED);
2802 _witness_debugger(int cond, const char *msg)
2805 if (witness_trace && cond)
2807 if (witness_kdb && cond)
2808 kdb_enter(KDB_WHY_WITNESS, msg);