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.
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13 * notice, this list of conditions and the following disclaimer in the
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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
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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 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(void(*)(const char *fmt, ...));
347 static void witness_ddb_display_descendants(void(*)(const char *fmt, ...),
348 struct witness *, int indent);
349 static void witness_ddb_display_list(void(*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 static void witness_setflag(struct lock_object *lock, int flag, int set);
374 #define witness_debugger(c) _witness_debugger(c, __func__)
376 #define witness_debugger(c)
379 SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, NULL, "Witness Locking");
382 * If set to 0, lock order checking is disabled. If set to -1,
383 * witness is completely disabled. Otherwise witness performs full
384 * lock order checking for all locks. At runtime, lock order checking
385 * may be toggled. However, witness cannot be reenabled once it is
386 * completely disabled.
388 static int witness_watch = 1;
389 TUNABLE_INT("debug.witness.watch", &witness_watch);
390 SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0,
391 sysctl_debug_witness_watch, "I", "witness is watching lock operations");
395 * When KDB is enabled and witness_kdb is 1, it will cause the system
396 * to drop into kdebug() when:
397 * - a lock hierarchy violation occurs
398 * - locks are held when going to sleep.
405 TUNABLE_INT("debug.witness.kdb", &witness_kdb);
406 SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, "");
409 * When KDB is enabled and witness_trace is 1, it will cause the system
410 * to print a stack trace:
411 * - a lock hierarchy violation occurs
412 * - locks are held when going to sleep.
414 int witness_trace = 1;
415 TUNABLE_INT("debug.witness.trace", &witness_trace);
416 SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, "");
419 #ifdef WITNESS_SKIPSPIN
420 int witness_skipspin = 1;
422 int witness_skipspin = 0;
424 TUNABLE_INT("debug.witness.skipspin", &witness_skipspin);
425 SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin,
429 * Call this to print out the relations between locks.
431 SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD,
432 NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs");
435 * Call this to print out the witness faulty stacks.
437 SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD,
438 NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks");
440 static struct mtx w_mtx;
443 static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free);
444 static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all);
447 static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin);
448 static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep);
451 static struct lock_list_entry *w_lock_list_free = NULL;
452 static struct witness_pendhelp pending_locks[WITNESS_PENDLIST];
453 static u_int pending_cnt;
455 static int w_free_cnt, w_spin_cnt, w_sleep_cnt;
456 SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, "");
457 SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, "");
458 SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0,
461 static struct witness *w_data;
462 static uint8_t w_rmatrix[WITNESS_COUNT+1][WITNESS_COUNT+1];
463 static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT];
464 static struct witness_hash w_hash; /* The witness hash table. */
466 /* The lock order data hash */
467 static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT];
468 static struct witness_lock_order_data *w_lofree = NULL;
469 static struct witness_lock_order_hash w_lohash;
470 static int w_max_used_index = 0;
471 static unsigned int w_generation = 0;
472 static const char *w_notrunning = "Witness not running\n";
473 static const char *w_stillcold = "Witness is still cold\n";
476 static struct witness_order_list_entry order_lists[] = {
480 { "proctree", &lock_class_sx },
481 { "allproc", &lock_class_sx },
482 { "allprison", &lock_class_sx },
487 { "Giant", &lock_class_mtx_sleep },
488 { "pipe mutex", &lock_class_mtx_sleep },
489 { "sigio lock", &lock_class_mtx_sleep },
490 { "process group", &lock_class_mtx_sleep },
491 { "process lock", &lock_class_mtx_sleep },
492 { "session", &lock_class_mtx_sleep },
493 { "uidinfo hash", &lock_class_rw },
495 { "pmc-sleep", &lock_class_mtx_sleep },
501 { "accept", &lock_class_mtx_sleep },
502 { "so_snd", &lock_class_mtx_sleep },
503 { "so_rcv", &lock_class_mtx_sleep },
504 { "sellck", &lock_class_mtx_sleep },
509 { "so_rcv", &lock_class_mtx_sleep },
510 { "radix node head", &lock_class_rw },
511 { "rtentry", &lock_class_mtx_sleep },
512 { "ifaddr", &lock_class_mtx_sleep },
515 * Multicast - protocol locks before interface locks, after UDP locks.
517 { "udpinp", &lock_class_rw },
518 { "in_multi_mtx", &lock_class_mtx_sleep },
519 { "igmp_mtx", &lock_class_mtx_sleep },
520 { "if_addr_mtx", &lock_class_mtx_sleep },
523 * UNIX Domain Sockets
525 { "unp", &lock_class_mtx_sleep },
526 { "so_snd", &lock_class_mtx_sleep },
531 { "udp", &lock_class_rw },
532 { "udpinp", &lock_class_rw },
533 { "so_snd", &lock_class_mtx_sleep },
538 { "tcp", &lock_class_rw },
539 { "tcpinp", &lock_class_rw },
540 { "so_snd", &lock_class_mtx_sleep },
545 { "slip_mtx", &lock_class_mtx_sleep },
546 { "slip sc_mtx", &lock_class_mtx_sleep },
551 { "ddp_list_mtx", &lock_class_mtx_sleep },
552 { "ddp_mtx", &lock_class_mtx_sleep },
557 { "bpf global lock", &lock_class_mtx_sleep },
558 { "bpf interface lock", &lock_class_mtx_sleep },
559 { "bpf cdev lock", &lock_class_mtx_sleep },
564 { "nfsd_mtx", &lock_class_mtx_sleep },
565 { "so_snd", &lock_class_mtx_sleep },
571 { "802.11 com lock", &lock_class_mtx_sleep},
576 { "network driver", &lock_class_mtx_sleep},
582 { "ng_node", &lock_class_mtx_sleep },
583 { "ng_worklist", &lock_class_mtx_sleep },
588 { "system map", &lock_class_mtx_sleep },
589 { "vm page queue mutex", &lock_class_mtx_sleep },
590 { "vnode interlock", &lock_class_mtx_sleep },
591 { "cdev", &lock_class_mtx_sleep },
594 * kqueue/VFS interaction
596 { "kqueue", &lock_class_mtx_sleep },
597 { "struct mount mtx", &lock_class_mtx_sleep },
598 { "vnode interlock", &lock_class_mtx_sleep },
604 { "ap boot", &lock_class_mtx_spin },
606 { "rm.mutex_mtx", &lock_class_mtx_spin },
607 { "sio", &lock_class_mtx_spin },
608 { "scrlock", &lock_class_mtx_spin },
610 { "cy", &lock_class_mtx_spin },
613 { "pcib_mtx", &lock_class_mtx_spin },
614 { "rtc_mtx", &lock_class_mtx_spin },
616 { "scc_hwmtx", &lock_class_mtx_spin },
617 { "uart_hwmtx", &lock_class_mtx_spin },
618 { "fast_taskqueue", &lock_class_mtx_spin },
619 { "intr table", &lock_class_mtx_spin },
621 { "pmc-per-proc", &lock_class_mtx_spin },
623 { "process slock", &lock_class_mtx_spin },
624 { "sleepq chain", &lock_class_mtx_spin },
625 { "umtx lock", &lock_class_mtx_spin },
626 { "rm_spinlock", &lock_class_mtx_spin },
627 { "turnstile chain", &lock_class_mtx_spin },
628 { "turnstile lock", &lock_class_mtx_spin },
629 { "sched lock", &lock_class_mtx_spin },
630 { "td_contested", &lock_class_mtx_spin },
631 { "callout", &lock_class_mtx_spin },
632 { "entropy harvest mutex", &lock_class_mtx_spin },
633 { "syscons video lock", &lock_class_mtx_spin },
634 { "time lock", &lock_class_mtx_spin },
636 { "smp rendezvous", &lock_class_mtx_spin },
639 { "tlb0", &lock_class_mtx_spin },
644 { "intrcnt", &lock_class_mtx_spin },
645 { "icu", &lock_class_mtx_spin },
646 #if defined(SMP) && defined(__sparc64__)
647 { "ipi", &lock_class_mtx_spin },
650 { "allpmaps", &lock_class_mtx_spin },
651 { "descriptor tables", &lock_class_mtx_spin },
653 { "clk", &lock_class_mtx_spin },
654 { "cpuset", &lock_class_mtx_spin },
655 { "mprof lock", &lock_class_mtx_spin },
656 { "zombie lock", &lock_class_mtx_spin },
657 { "ALD Queue", &lock_class_mtx_spin },
659 { "MCA spin lock", &lock_class_mtx_spin },
661 #if defined(__i386__) || defined(__amd64__)
662 { "pcicfg", &lock_class_mtx_spin },
663 { "NDIS thread lock", &lock_class_mtx_spin },
665 { "tw_osl_io_lock", &lock_class_mtx_spin },
666 { "tw_osl_q_lock", &lock_class_mtx_spin },
667 { "tw_cl_io_lock", &lock_class_mtx_spin },
668 { "tw_cl_intr_lock", &lock_class_mtx_spin },
669 { "tw_cl_gen_lock", &lock_class_mtx_spin },
671 { "pmc-leaf", &lock_class_mtx_spin },
673 { "blocked lock", &lock_class_mtx_spin },
680 * Pairs of locks which have been blessed
681 * Don't complain about order problems with blessed locks
683 static struct witness_blessed blessed_list[] = {
685 static int blessed_count =
686 sizeof(blessed_list) / sizeof(struct witness_blessed);
690 * This global is set to 0 once it becomes safe to use the witness code.
692 static int witness_cold = 1;
695 * This global is set to 1 once the static lock orders have been enrolled
696 * so that a warning can be issued for any spin locks enrolled later.
698 static int witness_spin_warn = 0;
701 * The WITNESS-enabled diagnostic code. Note that the witness code does
702 * assume that the early boot is single-threaded at least until after this
703 * routine is completed.
706 witness_initialize(void *dummy __unused)
708 struct lock_object *lock;
709 struct witness_order_list_entry *order;
710 struct witness *w, *w1;
713 w_data = malloc(sizeof (struct witness) * WITNESS_COUNT, M_WITNESS,
717 * We have to release Giant before initializing its witness
718 * structure so that WITNESS doesn't get confused.
721 mtx_assert(&Giant, MA_NOTOWNED);
723 CTR1(KTR_WITNESS, "%s: initializing witness", __func__);
724 mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET |
725 MTX_NOWITNESS | MTX_NOPROFILE);
726 for (i = WITNESS_COUNT - 1; i >= 0; i--) {
728 memset(w, 0, sizeof(*w));
729 w_data[i].w_index = i; /* Witness index never changes. */
732 KASSERT(STAILQ_FIRST(&w_free)->w_index == 0,
733 ("%s: Invalid list of free witness objects", __func__));
735 /* Witness with index 0 is not used to aid in debugging. */
736 STAILQ_REMOVE_HEAD(&w_free, w_list);
740 (sizeof(**w_rmatrix) * (WITNESS_COUNT+1) * (WITNESS_COUNT+1)));
742 for (i = 0; i < LOCK_CHILDCOUNT; i++)
743 witness_lock_list_free(&w_locklistdata[i]);
744 witness_init_hash_tables();
746 /* First add in all the specified order lists. */
747 for (order = order_lists; order->w_name != NULL; order++) {
748 w = enroll(order->w_name, order->w_class);
751 w->w_file = "order list";
752 for (order++; order->w_name != NULL; order++) {
753 w1 = enroll(order->w_name, order->w_class);
756 w1->w_file = "order list";
761 witness_spin_warn = 1;
763 /* Iterate through all locks and add them to witness. */
764 for (i = 0; pending_locks[i].wh_lock != NULL; i++) {
765 lock = pending_locks[i].wh_lock;
766 KASSERT(lock->lo_flags & LO_WITNESS,
767 ("%s: lock %s is on pending list but not LO_WITNESS",
768 __func__, lock->lo_name));
769 lock->lo_witness = enroll(pending_locks[i].wh_type,
773 /* Mark the witness code as being ready for use. */
778 SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize,
782 witness_init(struct lock_object *lock, const char *type)
784 struct lock_class *class;
786 /* Various sanity checks. */
787 class = LOCK_CLASS(lock);
788 if ((lock->lo_flags & LO_RECURSABLE) != 0 &&
789 (class->lc_flags & LC_RECURSABLE) == 0)
790 panic("%s: lock (%s) %s can not be recursable", __func__,
791 class->lc_name, lock->lo_name);
792 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
793 (class->lc_flags & LC_SLEEPABLE) == 0)
794 panic("%s: lock (%s) %s can not be sleepable", __func__,
795 class->lc_name, lock->lo_name);
796 if ((lock->lo_flags & LO_UPGRADABLE) != 0 &&
797 (class->lc_flags & LC_UPGRADABLE) == 0)
798 panic("%s: lock (%s) %s can not be upgradable", __func__,
799 class->lc_name, lock->lo_name);
802 * If we shouldn't watch this lock, then just clear lo_witness.
803 * Otherwise, if witness_cold is set, then it is too early to
804 * enroll this lock, so defer it to witness_initialize() by adding
805 * it to the pending_locks list. If it is not too early, then enroll
808 if (witness_watch < 1 || panicstr != NULL ||
809 (lock->lo_flags & LO_WITNESS) == 0)
810 lock->lo_witness = NULL;
811 else if (witness_cold) {
812 pending_locks[pending_cnt].wh_lock = lock;
813 pending_locks[pending_cnt++].wh_type = type;
814 if (pending_cnt > WITNESS_PENDLIST)
815 panic("%s: pending locks list is too small, bump it\n",
818 lock->lo_witness = enroll(type, class);
822 witness_destroy(struct lock_object *lock)
824 struct lock_class *class;
827 class = LOCK_CLASS(lock);
830 panic("lock (%s) %s destroyed while witness_cold",
831 class->lc_name, lock->lo_name);
833 /* XXX: need to verify that no one holds the lock */
834 if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL)
836 w = lock->lo_witness;
838 mtx_lock_spin(&w_mtx);
839 MPASS(w->w_refcount > 0);
842 if (w->w_refcount == 0)
844 mtx_unlock_spin(&w_mtx);
849 witness_ddb_compute_levels(void)
854 * First clear all levels.
856 STAILQ_FOREACH(w, &w_all, w_list)
860 * Look for locks with no parents and level all their descendants.
862 STAILQ_FOREACH(w, &w_all, w_list) {
864 /* If the witness has ancestors (is not a root), skip it. */
865 if (w->w_num_ancestors > 0)
867 witness_ddb_level_descendants(w, 0);
872 witness_ddb_level_descendants(struct witness *w, int l)
876 if (w->w_ddb_level >= l)
882 for (i = 1; i <= w_max_used_index; i++) {
883 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT)
884 witness_ddb_level_descendants(&w_data[i], l);
889 witness_ddb_display_descendants(void(*prnt)(const char *fmt, ...),
890 struct witness *w, int indent)
894 for (i = 0; i < indent; i++)
896 prnt("%s (type: %s, depth: %d, active refs: %d)",
897 w->w_name, w->w_class->lc_name,
898 w->w_ddb_level, w->w_refcount);
899 if (w->w_displayed) {
900 prnt(" -- (already displayed)\n");
904 if (w->w_file != NULL && w->w_line != 0)
905 prnt(" -- last acquired @ %s:%d\n", w->w_file,
908 prnt(" -- never acquired\n");
910 WITNESS_INDEX_ASSERT(w->w_index);
911 for (i = 1; i <= w_max_used_index; i++) {
912 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT)
913 witness_ddb_display_descendants(prnt, &w_data[i],
919 witness_ddb_display_list(void(*prnt)(const char *fmt, ...),
920 struct witness_list *list)
924 STAILQ_FOREACH(w, list, w_typelist) {
925 if (w->w_file == NULL || w->w_ddb_level > 0)
928 /* This lock has no anscestors - display its descendants. */
929 witness_ddb_display_descendants(prnt, w, 0);
934 witness_ddb_display(void(*prnt)(const char *fmt, ...))
938 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
939 witness_ddb_compute_levels();
941 /* Clear all the displayed flags. */
942 STAILQ_FOREACH(w, &w_all, w_list)
946 * First, handle sleep locks which have been acquired at least
949 prnt("Sleep locks:\n");
950 witness_ddb_display_list(prnt, &w_sleep);
953 * Now do spin locks which have been acquired at least once.
955 prnt("\nSpin locks:\n");
956 witness_ddb_display_list(prnt, &w_spin);
959 * Finally, any locks which have not been acquired yet.
961 prnt("\nLocks which were never acquired:\n");
962 STAILQ_FOREACH(w, &w_all, w_list) {
963 if (w->w_file != NULL || w->w_refcount == 0)
965 prnt("%s (type: %s, depth: %d)\n", w->w_name,
966 w->w_class->lc_name, w->w_ddb_level);
971 /* Trim useless garbage from filenames. */
973 fixup_filename(const char *file)
978 while (strncmp(file, "../", 3) == 0)
984 witness_defineorder(struct lock_object *lock1, struct lock_object *lock2)
987 if (witness_watch == -1 || panicstr != NULL)
990 /* Require locks that witness knows about. */
991 if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL ||
992 lock2->lo_witness == NULL)
995 mtx_assert(&w_mtx, MA_NOTOWNED);
996 mtx_lock_spin(&w_mtx);
999 * If we already have either an explicit or implied lock order that
1000 * is the other way around, then return an error.
1002 if (witness_watch &&
1003 isitmydescendant(lock2->lo_witness, lock1->lo_witness)) {
1004 mtx_unlock_spin(&w_mtx);
1008 /* Try to add the new order. */
1009 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
1010 lock2->lo_witness->w_name, lock1->lo_witness->w_name);
1011 itismychild(lock1->lo_witness, lock2->lo_witness);
1012 mtx_unlock_spin(&w_mtx);
1017 witness_checkorder(struct lock_object *lock, int flags, const char *file,
1018 int line, struct lock_object *interlock)
1020 struct lock_list_entry *lock_list, *lle;
1021 struct lock_instance *lock1, *lock2, *plock;
1022 struct lock_class *class;
1023 struct witness *w, *w1;
1027 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL ||
1031 w = lock->lo_witness;
1032 class = LOCK_CLASS(lock);
1034 file = fixup_filename(file);
1036 if (class->lc_flags & LC_SLEEPLOCK) {
1039 * Since spin locks include a critical section, this check
1040 * implicitly enforces a lock order of all sleep locks before
1043 if (td->td_critnest != 0 && !kdb_active)
1044 panic("blockable sleep lock (%s) %s @ %s:%d",
1045 class->lc_name, lock->lo_name, file, line);
1048 * If this is the first lock acquired then just return as
1049 * no order checking is needed.
1051 lock_list = td->td_sleeplocks;
1052 if (lock_list == NULL || lock_list->ll_count == 0)
1057 * If this is the first lock, just return as no order
1058 * checking is needed. Avoid problems with thread
1059 * migration pinning the thread while checking if
1060 * spinlocks are held. If at least one spinlock is held
1061 * the thread is in a safe path and it is allowed to
1065 lock_list = PCPU_GET(spinlocks);
1066 if (lock_list == NULL || lock_list->ll_count == 0) {
1074 * Check to see if we are recursing on a lock we already own. If
1075 * so, make sure that we don't mismatch exclusive and shared lock
1078 lock1 = find_instance(lock_list, lock);
1079 if (lock1 != NULL) {
1080 if ((lock1->li_flags & LI_EXCLUSIVE) != 0 &&
1081 (flags & LOP_EXCLUSIVE) == 0) {
1082 printf("shared lock of (%s) %s @ %s:%d\n",
1083 class->lc_name, lock->lo_name, file, line);
1084 printf("while exclusively locked from %s:%d\n",
1085 lock1->li_file, lock1->li_line);
1086 panic("share->excl");
1088 if ((lock1->li_flags & LI_EXCLUSIVE) == 0 &&
1089 (flags & LOP_EXCLUSIVE) != 0) {
1090 printf("exclusive lock of (%s) %s @ %s:%d\n",
1091 class->lc_name, lock->lo_name, file, line);
1092 printf("while share locked from %s:%d\n",
1093 lock1->li_file, lock1->li_line);
1094 panic("excl->share");
1100 * Find the previously acquired lock, but ignore interlocks.
1102 plock = &lock_list->ll_children[lock_list->ll_count - 1];
1103 if (interlock != NULL && plock->li_lock == interlock) {
1104 if (lock_list->ll_count > 1)
1106 &lock_list->ll_children[lock_list->ll_count - 2];
1108 lle = lock_list->ll_next;
1111 * The interlock is the only lock we hold, so
1116 plock = &lle->ll_children[lle->ll_count - 1];
1121 * Try to perform most checks without a lock. If this succeeds we
1122 * can skip acquiring the lock and return success.
1124 w1 = plock->li_lock->lo_witness;
1125 if (witness_lock_order_check(w1, w))
1129 * Check for duplicate locks of the same type. Note that we only
1130 * have to check for this on the last lock we just acquired. Any
1131 * other cases will be caught as lock order violations.
1133 mtx_lock_spin(&w_mtx);
1134 witness_lock_order_add(w1, w);
1137 if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) &&
1138 !(w_rmatrix[i][i] & WITNESS_REVERSAL)) {
1139 w_rmatrix[i][i] |= WITNESS_REVERSAL;
1141 mtx_unlock_spin(&w_mtx);
1143 "acquiring duplicate lock of same type: \"%s\"\n",
1145 printf(" 1st %s @ %s:%d\n", plock->li_lock->lo_name,
1146 plock->li_file, plock->li_line);
1147 printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line);
1148 witness_debugger(1);
1150 mtx_unlock_spin(&w_mtx);
1153 mtx_assert(&w_mtx, MA_OWNED);
1156 * If we know that the the lock we are acquiring comes after
1157 * the lock we most recently acquired in the lock order tree,
1158 * then there is no need for any further checks.
1160 if (isitmychild(w1, w))
1163 for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) {
1164 for (i = lle->ll_count - 1; i >= 0; i--, j++) {
1166 MPASS(j < WITNESS_COUNT);
1167 lock1 = &lle->ll_children[i];
1170 * Ignore the interlock the first time we see it.
1172 if (interlock != NULL && interlock == lock1->li_lock) {
1178 * If this lock doesn't undergo witness checking,
1181 w1 = lock1->li_lock->lo_witness;
1183 KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0,
1184 ("lock missing witness structure"));
1189 * If we are locking Giant and this is a sleepable
1190 * lock, then skip it.
1192 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 &&
1193 lock == &Giant.lock_object)
1197 * If we are locking a sleepable lock and this lock
1198 * is Giant, then skip it.
1200 if ((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1201 lock1->li_lock == &Giant.lock_object)
1205 * If we are locking a sleepable lock and this lock
1206 * isn't sleepable, we want to treat it as a lock
1207 * order violation to enfore a general lock order of
1208 * sleepable locks before non-sleepable locks.
1210 if (((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1211 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0))
1215 * If we are locking Giant and this is a non-sleepable
1216 * lock, then treat it as a reversal.
1218 if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 &&
1219 lock == &Giant.lock_object)
1223 * Check the lock order hierarchy for a reveresal.
1225 if (!isitmydescendant(w, w1))
1230 * We have a lock order violation, check to see if it
1231 * is allowed or has already been yelled about.
1236 * If the lock order is blessed, just bail. We don't
1237 * look for other lock order violations though, which
1244 /* Bail if this violation is known */
1245 if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL)
1248 /* Record this as a violation */
1249 w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL;
1250 w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL;
1251 w->w_reversed = w1->w_reversed = 1;
1252 witness_increment_graph_generation();
1253 mtx_unlock_spin(&w_mtx);
1256 * Ok, yell about it.
1258 if (((lock->lo_flags & LO_SLEEPABLE) != 0 &&
1259 (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0))
1261 "lock order reversal: (sleepable after non-sleepable)\n");
1262 else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0
1263 && lock == &Giant.lock_object)
1265 "lock order reversal: (Giant after non-sleepable)\n");
1267 printf("lock order reversal:\n");
1270 * Try to locate an earlier lock with
1271 * witness w in our list.
1274 lock2 = &lle->ll_children[i];
1275 MPASS(lock2->li_lock != NULL);
1276 if (lock2->li_lock->lo_witness == w)
1278 if (i == 0 && lle->ll_next != NULL) {
1280 i = lle->ll_count - 1;
1281 MPASS(i >= 0 && i < LOCK_NCHILDREN);
1286 printf(" 1st %p %s (%s) @ %s:%d\n",
1287 lock1->li_lock, lock1->li_lock->lo_name,
1288 w1->w_name, lock1->li_file, lock1->li_line);
1289 printf(" 2nd %p %s (%s) @ %s:%d\n", lock,
1290 lock->lo_name, w->w_name, file, line);
1292 printf(" 1st %p %s (%s) @ %s:%d\n",
1293 lock2->li_lock, lock2->li_lock->lo_name,
1294 lock2->li_lock->lo_witness->w_name,
1295 lock2->li_file, lock2->li_line);
1296 printf(" 2nd %p %s (%s) @ %s:%d\n",
1297 lock1->li_lock, lock1->li_lock->lo_name,
1298 w1->w_name, lock1->li_file, lock1->li_line);
1299 printf(" 3rd %p %s (%s) @ %s:%d\n", lock,
1300 lock->lo_name, w->w_name, file, line);
1302 witness_debugger(1);
1308 * If requested, build a new lock order. However, don't build a new
1309 * relationship between a sleepable lock and Giant if it is in the
1310 * wrong direction. The correct lock order is that sleepable locks
1311 * always come before Giant.
1313 if (flags & LOP_NEWORDER &&
1314 !(plock->li_lock == &Giant.lock_object &&
1315 (lock->lo_flags & LO_SLEEPABLE) != 0)) {
1316 CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__,
1317 w->w_name, plock->li_lock->lo_witness->w_name);
1318 itismychild(plock->li_lock->lo_witness, w);
1321 mtx_unlock_spin(&w_mtx);
1325 witness_lock(struct lock_object *lock, int flags, const char *file, int line)
1327 struct lock_list_entry **lock_list, *lle;
1328 struct lock_instance *instance;
1332 if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL ||
1335 w = lock->lo_witness;
1337 file = fixup_filename(file);
1339 /* Determine lock list for this lock. */
1340 if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK)
1341 lock_list = &td->td_sleeplocks;
1343 lock_list = PCPU_PTR(spinlocks);
1345 /* Check to see if we are recursing on a lock we already own. */
1346 instance = find_instance(*lock_list, lock);
1347 if (instance != NULL) {
1348 instance->li_flags++;
1349 CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__,
1350 td->td_proc->p_pid, lock->lo_name,
1351 instance->li_flags & LI_RECURSEMASK);
1352 instance->li_file = file;
1353 instance->li_line = line;
1357 /* Update per-witness last file and line acquire. */
1361 /* Find the next open lock instance in the list and fill it. */
1363 if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) {
1364 lle = witness_lock_list_get();
1367 lle->ll_next = *lock_list;
1368 CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__,
1369 td->td_proc->p_pid, lle);
1372 instance = &lle->ll_children[lle->ll_count++];
1373 instance->li_lock = lock;
1374 instance->li_line = line;
1375 instance->li_file = file;
1376 if ((flags & LOP_EXCLUSIVE) != 0)
1377 instance->li_flags = LI_EXCLUSIVE;
1379 instance->li_flags = 0;
1380 CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__,
1381 td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1);
1385 witness_upgrade(struct lock_object *lock, int flags, const char *file, int line)
1387 struct lock_instance *instance;
1388 struct lock_class *class;
1390 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1391 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
1393 class = LOCK_CLASS(lock);
1394 file = fixup_filename(file);
1395 if (witness_watch) {
1396 if ((lock->lo_flags & LO_UPGRADABLE) == 0)
1397 panic("upgrade of non-upgradable lock (%s) %s @ %s:%d",
1398 class->lc_name, lock->lo_name, file, line);
1399 if ((class->lc_flags & LC_SLEEPLOCK) == 0)
1400 panic("upgrade of non-sleep lock (%s) %s @ %s:%d",
1401 class->lc_name, lock->lo_name, file, line);
1403 instance = find_instance(curthread->td_sleeplocks, lock);
1404 if (instance == NULL)
1405 panic("upgrade of unlocked lock (%s) %s @ %s:%d",
1406 class->lc_name, lock->lo_name, file, line);
1407 if (witness_watch) {
1408 if ((instance->li_flags & LI_EXCLUSIVE) != 0)
1409 panic("upgrade of exclusive lock (%s) %s @ %s:%d",
1410 class->lc_name, lock->lo_name, file, line);
1411 if ((instance->li_flags & LI_RECURSEMASK) != 0)
1412 panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d",
1413 class->lc_name, lock->lo_name,
1414 instance->li_flags & LI_RECURSEMASK, file, line);
1416 instance->li_flags |= LI_EXCLUSIVE;
1420 witness_downgrade(struct lock_object *lock, int flags, const char *file,
1423 struct lock_instance *instance;
1424 struct lock_class *class;
1426 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
1427 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
1429 class = LOCK_CLASS(lock);
1430 file = fixup_filename(file);
1431 if (witness_watch) {
1432 if ((lock->lo_flags & LO_UPGRADABLE) == 0)
1433 panic("downgrade of non-upgradable lock (%s) %s @ %s:%d",
1434 class->lc_name, lock->lo_name, file, line);
1435 if ((class->lc_flags & LC_SLEEPLOCK) == 0)
1436 panic("downgrade of non-sleep lock (%s) %s @ %s:%d",
1437 class->lc_name, lock->lo_name, file, line);
1439 instance = find_instance(curthread->td_sleeplocks, lock);
1440 if (instance == NULL)
1441 panic("downgrade of unlocked lock (%s) %s @ %s:%d",
1442 class->lc_name, lock->lo_name, file, line);
1443 if (witness_watch) {
1444 if ((instance->li_flags & LI_EXCLUSIVE) == 0)
1445 panic("downgrade of shared lock (%s) %s @ %s:%d",
1446 class->lc_name, lock->lo_name, file, line);
1447 if ((instance->li_flags & LI_RECURSEMASK) != 0)
1448 panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d",
1449 class->lc_name, lock->lo_name,
1450 instance->li_flags & LI_RECURSEMASK, file, line);
1452 instance->li_flags &= ~LI_EXCLUSIVE;
1456 witness_unlock(struct lock_object *lock, int flags, const char *file, int line)
1458 struct lock_list_entry **lock_list, *lle;
1459 struct lock_instance *instance;
1460 struct lock_class *class;
1465 if (witness_cold || lock->lo_witness == NULL || panicstr != NULL)
1468 class = LOCK_CLASS(lock);
1469 file = fixup_filename(file);
1471 /* Find lock instance associated with this lock. */
1472 if (class->lc_flags & LC_SLEEPLOCK)
1473 lock_list = &td->td_sleeplocks;
1475 lock_list = PCPU_PTR(spinlocks);
1477 for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next)
1478 for (i = 0; i < (*lock_list)->ll_count; i++) {
1479 instance = &(*lock_list)->ll_children[i];
1480 if (instance->li_lock == lock)
1485 * When disabling WITNESS through witness_watch we could end up in
1486 * having registered locks in the td_sleeplocks queue.
1487 * We have to make sure we flush these queues, so just search for
1488 * eventual register locks and remove them.
1490 if (witness_watch > 0)
1491 panic("lock (%s) %s not locked @ %s:%d", class->lc_name,
1492 lock->lo_name, file, line);
1497 /* First, check for shared/exclusive mismatches. */
1498 if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 &&
1499 (flags & LOP_EXCLUSIVE) == 0) {
1500 printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name,
1501 lock->lo_name, file, line);
1502 printf("while exclusively locked from %s:%d\n",
1503 instance->li_file, instance->li_line);
1504 panic("excl->ushare");
1506 if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 &&
1507 (flags & LOP_EXCLUSIVE) != 0) {
1508 printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name,
1509 lock->lo_name, file, line);
1510 printf("while share locked from %s:%d\n", instance->li_file,
1512 panic("share->uexcl");
1514 if ((instance->li_flags & LI_NORELEASE) != 0 && witness_watch > 0) {
1515 printf("forbidden unlock of (%s) %s @ %s:%d\n", class->lc_name,
1516 lock->lo_name, file, line);
1517 panic("lock marked norelease");
1520 /* If we are recursed, unrecurse. */
1521 if ((instance->li_flags & LI_RECURSEMASK) > 0) {
1522 CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__,
1523 td->td_proc->p_pid, instance->li_lock->lo_name,
1524 instance->li_flags);
1525 instance->li_flags--;
1529 /* Otherwise, remove this item from the list. */
1531 CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__,
1532 td->td_proc->p_pid, instance->li_lock->lo_name,
1533 (*lock_list)->ll_count - 1);
1534 for (j = i; j < (*lock_list)->ll_count - 1; j++)
1535 (*lock_list)->ll_children[j] =
1536 (*lock_list)->ll_children[j + 1];
1537 (*lock_list)->ll_count--;
1541 * In order to reduce contention on w_mtx, we want to keep always an
1542 * head object into lists so that frequent allocation from the
1543 * free witness pool (and subsequent locking) is avoided.
1544 * In order to maintain the current code simple, when the head
1545 * object is totally unloaded it means also that we do not have
1546 * further objects in the list, so the list ownership needs to be
1547 * hand over to another object if the current head needs to be freed.
1549 if ((*lock_list)->ll_count == 0) {
1550 if (*lock_list == lle) {
1551 if (lle->ll_next == NULL)
1555 *lock_list = lle->ll_next;
1556 CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__,
1557 td->td_proc->p_pid, lle);
1558 witness_lock_list_free(lle);
1563 witness_thread_exit(struct thread *td)
1565 struct lock_list_entry *lle;
1568 lle = td->td_sleeplocks;
1569 if (lle == NULL || panicstr != NULL)
1571 if (lle->ll_count != 0) {
1572 for (n = 0; lle != NULL; lle = lle->ll_next)
1573 for (i = lle->ll_count - 1; i >= 0; i--) {
1575 printf("Thread %p exiting with the following locks held:\n",
1578 witness_list_lock(&lle->ll_children[i]);
1581 panic("Thread %p cannot exit while holding sleeplocks\n", td);
1583 witness_lock_list_free(lle);
1587 * Warn if any locks other than 'lock' are held. Flags can be passed in to
1588 * exempt Giant and sleepable locks from the checks as well. If any
1589 * non-exempt locks are held, then a supplied message is printed to the
1590 * console along with a list of the offending locks. If indicated in the
1591 * flags then a failure results in a panic as well.
1594 witness_warn(int flags, struct lock_object *lock, const char *fmt, ...)
1596 struct lock_list_entry *lock_list, *lle;
1597 struct lock_instance *lock1;
1602 if (witness_cold || witness_watch < 1 || panicstr != NULL)
1606 for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next)
1607 for (i = lle->ll_count - 1; i >= 0; i--) {
1608 lock1 = &lle->ll_children[i];
1609 if (lock1->li_lock == lock)
1611 if (flags & WARN_GIANTOK &&
1612 lock1->li_lock == &Giant.lock_object)
1614 if (flags & WARN_SLEEPOK &&
1615 (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0)
1621 printf(" with the following");
1622 if (flags & WARN_SLEEPOK)
1623 printf(" non-sleepable");
1624 printf(" locks held:\n");
1627 witness_list_lock(lock1);
1631 * Pin the thread in order to avoid problems with thread migration.
1632 * Once that all verifies are passed about spinlocks ownership,
1633 * the thread is in a safe path and it can be unpinned.
1636 lock_list = PCPU_GET(spinlocks);
1637 if (lock_list != NULL && lock_list->ll_count != 0) {
1641 * We should only have one spinlock and as long as
1642 * the flags cannot match for this locks class,
1643 * check if the first spinlock is the one curthread
1646 lock1 = &lock_list->ll_children[lock_list->ll_count - 1];
1647 if (lock_list->ll_count == 1 && lock_list->ll_next == NULL &&
1648 lock1->li_lock == lock && n == 0)
1654 printf(" with the following");
1655 if (flags & WARN_SLEEPOK)
1656 printf(" non-sleepable");
1657 printf(" locks held:\n");
1658 n += witness_list_locks(&lock_list);
1661 if (flags & WARN_PANIC && n)
1662 panic("%s", __func__);
1664 witness_debugger(n);
1669 witness_file(struct lock_object *lock)
1673 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
1675 w = lock->lo_witness;
1680 witness_line(struct lock_object *lock)
1684 if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL)
1686 w = lock->lo_witness;
1690 static struct witness *
1691 enroll(const char *description, struct lock_class *lock_class)
1694 struct witness_list *typelist;
1696 MPASS(description != NULL);
1698 if (witness_watch == -1 || panicstr != NULL)
1700 if ((lock_class->lc_flags & LC_SPINLOCK)) {
1701 if (witness_skipspin)
1705 } else if ((lock_class->lc_flags & LC_SLEEPLOCK))
1706 typelist = &w_sleep;
1708 panic("lock class %s is not sleep or spin",
1709 lock_class->lc_name);
1711 mtx_lock_spin(&w_mtx);
1712 w = witness_hash_get(description);
1715 if ((w = witness_get()) == NULL)
1717 MPASS(strlen(description) < MAX_W_NAME);
1718 strcpy(w->w_name, description);
1719 w->w_class = lock_class;
1721 STAILQ_INSERT_HEAD(&w_all, w, w_list);
1722 if (lock_class->lc_flags & LC_SPINLOCK) {
1723 STAILQ_INSERT_HEAD(&w_spin, w, w_typelist);
1725 } else if (lock_class->lc_flags & LC_SLEEPLOCK) {
1726 STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist);
1730 /* Insert new witness into the hash */
1731 witness_hash_put(w);
1732 witness_increment_graph_generation();
1733 mtx_unlock_spin(&w_mtx);
1737 mtx_unlock_spin(&w_mtx);
1738 if (lock_class != w->w_class)
1740 "lock (%s) %s does not match earlier (%s) lock",
1741 description, lock_class->lc_name,
1742 w->w_class->lc_name);
1747 depart(struct witness *w)
1749 struct witness_list *list;
1751 MPASS(w->w_refcount == 0);
1752 if (w->w_class->lc_flags & LC_SLEEPLOCK) {
1760 * Set file to NULL as it may point into a loadable module.
1764 witness_increment_graph_generation();
1769 adopt(struct witness *parent, struct witness *child)
1773 if (witness_cold == 0)
1774 mtx_assert(&w_mtx, MA_OWNED);
1776 /* If the relationship is already known, there's no work to be done. */
1777 if (isitmychild(parent, child))
1780 /* When the structure of the graph changes, bump up the generation. */
1781 witness_increment_graph_generation();
1784 * The hard part ... create the direct relationship, then propagate all
1785 * indirect relationships.
1787 pi = parent->w_index;
1788 ci = child->w_index;
1789 WITNESS_INDEX_ASSERT(pi);
1790 WITNESS_INDEX_ASSERT(ci);
1792 w_rmatrix[pi][ci] |= WITNESS_PARENT;
1793 w_rmatrix[ci][pi] |= WITNESS_CHILD;
1796 * If parent was not already an ancestor of child,
1797 * then we increment the descendant and ancestor counters.
1799 if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) {
1800 parent->w_num_descendants++;
1801 child->w_num_ancestors++;
1805 * Find each ancestor of 'pi'. Note that 'pi' itself is counted as
1806 * an ancestor of 'pi' during this loop.
1808 for (i = 1; i <= w_max_used_index; i++) {
1809 if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 &&
1813 /* Find each descendant of 'i' and mark it as a descendant. */
1814 for (j = 1; j <= w_max_used_index; j++) {
1817 * Skip children that are already marked as
1818 * descendants of 'i'.
1820 if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK)
1824 * We are only interested in descendants of 'ci'. Note
1825 * that 'ci' itself is counted as a descendant of 'ci'.
1827 if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 &&
1830 w_rmatrix[i][j] |= WITNESS_ANCESTOR;
1831 w_rmatrix[j][i] |= WITNESS_DESCENDANT;
1832 w_data[i].w_num_descendants++;
1833 w_data[j].w_num_ancestors++;
1836 * Make sure we aren't marking a node as both an
1837 * ancestor and descendant. We should have caught
1838 * this as a lock order reversal earlier.
1840 if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) &&
1841 (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) {
1842 printf("witness rmatrix paradox! [%d][%d]=%d "
1843 "both ancestor and descendant\n",
1844 i, j, w_rmatrix[i][j]);
1846 printf("Witness disabled.\n");
1849 if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) &&
1850 (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) {
1851 printf("witness rmatrix paradox! [%d][%d]=%d "
1852 "both ancestor and descendant\n",
1853 j, i, w_rmatrix[j][i]);
1855 printf("Witness disabled.\n");
1863 itismychild(struct witness *parent, struct witness *child)
1866 MPASS(child != NULL && parent != NULL);
1867 if (witness_cold == 0)
1868 mtx_assert(&w_mtx, MA_OWNED);
1870 if (!witness_lock_type_equal(parent, child)) {
1871 if (witness_cold == 0)
1872 mtx_unlock_spin(&w_mtx);
1873 panic("%s: parent \"%s\" (%s) and child \"%s\" (%s) are not "
1874 "the same lock type", __func__, parent->w_name,
1875 parent->w_class->lc_name, child->w_name,
1876 child->w_class->lc_name);
1878 adopt(parent, child);
1882 * Generic code for the isitmy*() functions. The rmask parameter is the
1883 * expected relationship of w1 to w2.
1886 _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname)
1888 unsigned char r1, r2;
1893 WITNESS_INDEX_ASSERT(i1);
1894 WITNESS_INDEX_ASSERT(i2);
1895 r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK;
1896 r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK;
1898 /* The flags on one better be the inverse of the flags on the other */
1899 if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) ||
1900 (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) {
1901 printf("%s: rmatrix mismatch between %s (index %d) and %s "
1902 "(index %d): w_rmatrix[%d][%d] == %hhx but "
1903 "w_rmatrix[%d][%d] == %hhx\n",
1904 fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1,
1907 printf("Witness disabled.\n");
1910 return (r1 & rmask);
1914 * Checks if @child is a direct child of @parent.
1917 isitmychild(struct witness *parent, struct witness *child)
1920 return (_isitmyx(parent, child, WITNESS_PARENT, __func__));
1924 * Checks if @descendant is a direct or inderect descendant of @ancestor.
1927 isitmydescendant(struct witness *ancestor, struct witness *descendant)
1930 return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK,
1936 blessed(struct witness *w1, struct witness *w2)
1939 struct witness_blessed *b;
1941 for (i = 0; i < blessed_count; i++) {
1942 b = &blessed_list[i];
1943 if (strcmp(w1->w_name, b->b_lock1) == 0) {
1944 if (strcmp(w2->w_name, b->b_lock2) == 0)
1948 if (strcmp(w1->w_name, b->b_lock2) == 0)
1949 if (strcmp(w2->w_name, b->b_lock1) == 0)
1956 static struct witness *
1962 if (witness_cold == 0)
1963 mtx_assert(&w_mtx, MA_OWNED);
1965 if (witness_watch == -1) {
1966 mtx_unlock_spin(&w_mtx);
1969 if (STAILQ_EMPTY(&w_free)) {
1971 mtx_unlock_spin(&w_mtx);
1972 printf("WITNESS: unable to allocate a new witness object\n");
1975 w = STAILQ_FIRST(&w_free);
1976 STAILQ_REMOVE_HEAD(&w_free, w_list);
1979 MPASS(index > 0 && index == w_max_used_index+1 &&
1980 index < WITNESS_COUNT);
1981 bzero(w, sizeof(*w));
1983 if (index > w_max_used_index)
1984 w_max_used_index = index;
1989 witness_free(struct witness *w)
1992 STAILQ_INSERT_HEAD(&w_free, w, w_list);
1996 static struct lock_list_entry *
1997 witness_lock_list_get(void)
1999 struct lock_list_entry *lle;
2001 if (witness_watch == -1)
2003 mtx_lock_spin(&w_mtx);
2004 lle = w_lock_list_free;
2007 mtx_unlock_spin(&w_mtx);
2008 printf("%s: witness exhausted\n", __func__);
2011 w_lock_list_free = lle->ll_next;
2012 mtx_unlock_spin(&w_mtx);
2013 bzero(lle, sizeof(*lle));
2018 witness_lock_list_free(struct lock_list_entry *lle)
2021 mtx_lock_spin(&w_mtx);
2022 lle->ll_next = w_lock_list_free;
2023 w_lock_list_free = lle;
2024 mtx_unlock_spin(&w_mtx);
2027 static struct lock_instance *
2028 find_instance(struct lock_list_entry *list, struct lock_object *lock)
2030 struct lock_list_entry *lle;
2031 struct lock_instance *instance;
2034 for (lle = list; lle != NULL; lle = lle->ll_next)
2035 for (i = lle->ll_count - 1; i >= 0; i--) {
2036 instance = &lle->ll_children[i];
2037 if (instance->li_lock == lock)
2044 witness_list_lock(struct lock_instance *instance)
2046 struct lock_object *lock;
2048 lock = instance->li_lock;
2049 printf("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ?
2050 "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name);
2051 if (lock->lo_witness->w_name != lock->lo_name)
2052 printf(" (%s)", lock->lo_witness->w_name);
2053 printf(" r = %d (%p) locked @ %s:%d\n",
2054 instance->li_flags & LI_RECURSEMASK, lock, instance->li_file,
2060 witness_thread_has_locks(struct thread *td)
2063 if (td->td_sleeplocks == NULL)
2065 return (td->td_sleeplocks->ll_count != 0);
2069 witness_proc_has_locks(struct proc *p)
2073 FOREACH_THREAD_IN_PROC(p, td) {
2074 if (witness_thread_has_locks(td))
2082 witness_list_locks(struct lock_list_entry **lock_list)
2084 struct lock_list_entry *lle;
2088 for (lle = *lock_list; lle != NULL; lle = lle->ll_next)
2089 for (i = lle->ll_count - 1; i >= 0; i--) {
2090 witness_list_lock(&lle->ll_children[i]);
2097 * This is a bit risky at best. We call this function when we have timed
2098 * out acquiring a spin lock, and we assume that the other CPU is stuck
2099 * with this lock held. So, we go groveling around in the other CPU's
2100 * per-cpu data to try to find the lock instance for this spin lock to
2101 * see when it was last acquired.
2104 witness_display_spinlock(struct lock_object *lock, struct thread *owner)
2106 struct lock_instance *instance;
2109 if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU)
2111 pc = pcpu_find(owner->td_oncpu);
2112 instance = find_instance(pc->pc_spinlocks, lock);
2113 if (instance != NULL)
2114 witness_list_lock(instance);
2118 witness_save(struct lock_object *lock, const char **filep, int *linep)
2120 struct lock_list_entry *lock_list;
2121 struct lock_instance *instance;
2122 struct lock_class *class;
2124 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2125 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2127 class = LOCK_CLASS(lock);
2128 if (class->lc_flags & LC_SLEEPLOCK)
2129 lock_list = curthread->td_sleeplocks;
2131 if (witness_skipspin)
2133 lock_list = PCPU_GET(spinlocks);
2135 instance = find_instance(lock_list, lock);
2136 if (instance == NULL)
2137 panic("%s: lock (%s) %s not locked", __func__,
2138 class->lc_name, lock->lo_name);
2139 *filep = instance->li_file;
2140 *linep = instance->li_line;
2144 witness_restore(struct lock_object *lock, const char *file, int line)
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 lock->lo_witness->w_file = file;
2166 lock->lo_witness->w_line = line;
2167 instance->li_file = file;
2168 instance->li_line = line;
2172 witness_assert(struct lock_object *lock, int flags, const char *file, int line)
2174 #ifdef INVARIANT_SUPPORT
2175 struct lock_instance *instance;
2176 struct lock_class *class;
2178 if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL)
2180 class = LOCK_CLASS(lock);
2181 if ((class->lc_flags & LC_SLEEPLOCK) != 0)
2182 instance = find_instance(curthread->td_sleeplocks, lock);
2183 else if ((class->lc_flags & LC_SPINLOCK) != 0)
2184 instance = find_instance(PCPU_GET(spinlocks), lock);
2186 panic("Lock (%s) %s is not sleep or spin!",
2187 class->lc_name, lock->lo_name);
2189 file = fixup_filename(file);
2192 if (instance != NULL)
2193 panic("Lock (%s) %s locked @ %s:%d.",
2194 class->lc_name, lock->lo_name, file, line);
2197 case LA_LOCKED | LA_RECURSED:
2198 case LA_LOCKED | LA_NOTRECURSED:
2200 case LA_SLOCKED | LA_RECURSED:
2201 case LA_SLOCKED | LA_NOTRECURSED:
2203 case LA_XLOCKED | LA_RECURSED:
2204 case LA_XLOCKED | LA_NOTRECURSED:
2205 if (instance == NULL) {
2206 panic("Lock (%s) %s not locked @ %s:%d.",
2207 class->lc_name, lock->lo_name, file, line);
2210 if ((flags & LA_XLOCKED) != 0 &&
2211 (instance->li_flags & LI_EXCLUSIVE) == 0)
2212 panic("Lock (%s) %s not exclusively locked @ %s:%d.",
2213 class->lc_name, lock->lo_name, file, line);
2214 if ((flags & LA_SLOCKED) != 0 &&
2215 (instance->li_flags & LI_EXCLUSIVE) != 0)
2216 panic("Lock (%s) %s exclusively locked @ %s:%d.",
2217 class->lc_name, lock->lo_name, file, line);
2218 if ((flags & LA_RECURSED) != 0 &&
2219 (instance->li_flags & LI_RECURSEMASK) == 0)
2220 panic("Lock (%s) %s not recursed @ %s:%d.",
2221 class->lc_name, lock->lo_name, file, line);
2222 if ((flags & LA_NOTRECURSED) != 0 &&
2223 (instance->li_flags & LI_RECURSEMASK) != 0)
2224 panic("Lock (%s) %s recursed @ %s:%d.",
2225 class->lc_name, lock->lo_name, file, line);
2228 panic("Invalid lock assertion at %s:%d.", file, line);
2231 #endif /* INVARIANT_SUPPORT */
2235 witness_setflag(struct lock_object *lock, int flag, int set)
2237 struct lock_list_entry *lock_list;
2238 struct lock_instance *instance;
2239 struct lock_class *class;
2241 if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL)
2243 class = LOCK_CLASS(lock);
2244 if (class->lc_flags & LC_SLEEPLOCK)
2245 lock_list = curthread->td_sleeplocks;
2247 if (witness_skipspin)
2249 lock_list = PCPU_GET(spinlocks);
2251 instance = find_instance(lock_list, lock);
2252 if (instance == NULL)
2253 panic("%s: lock (%s) %s not locked", __func__,
2254 class->lc_name, lock->lo_name);
2257 instance->li_flags |= flag;
2259 instance->li_flags &= ~flag;
2263 witness_norelease(struct lock_object *lock)
2266 witness_setflag(lock, LI_NORELEASE, 1);
2270 witness_releaseok(struct lock_object *lock)
2273 witness_setflag(lock, LI_NORELEASE, 0);
2278 witness_ddb_list(struct thread *td)
2281 KASSERT(witness_cold == 0, ("%s: witness_cold", __func__));
2282 KASSERT(kdb_active, ("%s: not in the debugger", __func__));
2284 if (witness_watch < 1)
2287 witness_list_locks(&td->td_sleeplocks);
2290 * We only handle spinlocks if td == curthread. This is somewhat broken
2291 * if td is currently executing on some other CPU and holds spin locks
2292 * as we won't display those locks. If we had a MI way of getting
2293 * the per-cpu data for a given cpu then we could use
2294 * td->td_oncpu to get the list of spinlocks for this thread
2297 * That still wouldn't really fix this unless we locked the scheduler
2298 * lock or stopped the other CPU to make sure it wasn't changing the
2299 * list out from under us. It is probably best to just not try to
2300 * handle threads on other CPU's for now.
2302 if (td == curthread && PCPU_GET(spinlocks) != NULL)
2303 witness_list_locks(PCPU_PTR(spinlocks));
2306 DB_SHOW_COMMAND(locks, db_witness_list)
2311 td = db_lookup_thread(addr, TRUE);
2314 witness_ddb_list(td);
2317 DB_SHOW_ALL_COMMAND(locks, db_witness_list_all)
2323 * It would be nice to list only threads and processes that actually
2324 * held sleep locks, but that information is currently not exported
2327 FOREACH_PROC_IN_SYSTEM(p) {
2328 if (!witness_proc_has_locks(p))
2330 FOREACH_THREAD_IN_PROC(p, td) {
2331 if (!witness_thread_has_locks(td))
2333 db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid,
2334 p->p_comm, td, td->td_tid);
2335 witness_ddb_list(td);
2339 DB_SHOW_ALIAS(alllocks, db_witness_list_all)
2341 DB_SHOW_COMMAND(witness, db_witness_display)
2344 witness_ddb_display(db_printf);
2349 sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS)
2351 struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2;
2352 struct witness *tmp_w1, *tmp_w2, *w1, *w2;
2354 u_int w_rmatrix1, w_rmatrix2;
2355 int error, generation, i, j;
2361 if (witness_watch < 1) {
2362 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
2366 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
2370 sb = sbuf_new(NULL, NULL, BADSTACK_SBUF_SIZE, SBUF_AUTOEXTEND);
2374 /* Allocate and init temporary storage space. */
2375 tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
2376 tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO);
2377 tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP,
2379 tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP,
2381 stack_zero(&tmp_data1->wlod_stack);
2382 stack_zero(&tmp_data2->wlod_stack);
2385 mtx_lock_spin(&w_mtx);
2386 generation = w_generation;
2387 mtx_unlock_spin(&w_mtx);
2388 sbuf_printf(sb, "Number of known direct relationships is %d\n",
2389 w_lohash.wloh_count);
2390 for (i = 1; i < w_max_used_index; i++) {
2391 mtx_lock_spin(&w_mtx);
2392 if (generation != w_generation) {
2393 mtx_unlock_spin(&w_mtx);
2395 /* The graph has changed, try again. */
2402 if (w1->w_reversed == 0) {
2403 mtx_unlock_spin(&w_mtx);
2407 /* Copy w1 locally so we can release the spin lock. */
2409 mtx_unlock_spin(&w_mtx);
2411 if (tmp_w1->w_reversed == 0)
2413 for (j = 1; j < w_max_used_index; j++) {
2414 if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j)
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 data1 = witness_lock_order_get(w1, w2);
2429 data2 = witness_lock_order_get(w2, w1);
2432 * Copy information locally so we can release the
2436 w_rmatrix1 = (unsigned int)w_rmatrix[i][j];
2437 w_rmatrix2 = (unsigned int)w_rmatrix[j][i];
2440 stack_zero(&tmp_data1->wlod_stack);
2441 stack_copy(&data1->wlod_stack,
2442 &tmp_data1->wlod_stack);
2444 if (data2 && data2 != data1) {
2445 stack_zero(&tmp_data2->wlod_stack);
2446 stack_copy(&data2->wlod_stack,
2447 &tmp_data2->wlod_stack);
2449 mtx_unlock_spin(&w_mtx);
2452 "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n",
2453 tmp_w1->w_name, tmp_w1->w_class->lc_name,
2454 tmp_w2->w_name, tmp_w2->w_class->lc_name);
2457 "w_rmatrix[%s][%s] == %x, w_rmatrix[%s][%s] == %x\n",
2458 tmp_w1->name, tmp_w2->w_name, w_rmatrix1,
2459 tmp_w2->name, tmp_w1->w_name, w_rmatrix2);
2463 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
2464 tmp_w1->w_name, tmp_w1->w_class->lc_name,
2465 tmp_w2->w_name, tmp_w2->w_class->lc_name);
2466 stack_sbuf_print(sb, &tmp_data1->wlod_stack);
2467 sbuf_printf(sb, "\n");
2469 if (data2 && data2 != data1) {
2471 "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n",
2472 tmp_w2->w_name, tmp_w2->w_class->lc_name,
2473 tmp_w1->w_name, tmp_w1->w_class->lc_name);
2474 stack_sbuf_print(sb, &tmp_data2->wlod_stack);
2475 sbuf_printf(sb, "\n");
2479 mtx_lock_spin(&w_mtx);
2480 if (generation != w_generation) {
2481 mtx_unlock_spin(&w_mtx);
2484 * The graph changed while we were printing stack data,
2491 mtx_unlock_spin(&w_mtx);
2493 /* Free temporary storage space. */
2494 free(tmp_data1, M_TEMP);
2495 free(tmp_data2, M_TEMP);
2496 free(tmp_w1, M_TEMP);
2497 free(tmp_w2, M_TEMP);
2500 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
2507 sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS)
2513 if (witness_watch < 1) {
2514 error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning));
2518 error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold));
2522 sb = sbuf_new(NULL, NULL, FULLGRAPH_SBUF_SIZE, SBUF_FIXEDLEN);
2525 sbuf_printf(sb, "\n");
2527 mtx_lock_spin(&w_mtx);
2528 STAILQ_FOREACH(w, &w_all, w_list)
2530 STAILQ_FOREACH(w, &w_all, w_list)
2531 witness_add_fullgraph(sb, w);
2532 mtx_unlock_spin(&w_mtx);
2535 * While using SBUF_FIXEDLEN, check if the sbuf overflowed.
2537 if (sbuf_overflowed(sb)) {
2539 panic("%s: sbuf overflowed, bump FULLGRAPH_SBUF_SIZE value\n",
2544 * Close the sbuf and return to userland.
2547 error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
2554 sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS)
2558 value = witness_watch;
2559 error = sysctl_handle_int(oidp, &value, 0, req);
2560 if (error != 0 || req->newptr == NULL)
2562 if (value > 1 || value < -1 ||
2563 (witness_watch == -1 && value != witness_watch))
2565 witness_watch = value;
2570 witness_add_fullgraph(struct sbuf *sb, struct witness *w)
2574 if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0))
2578 WITNESS_INDEX_ASSERT(w->w_index);
2579 for (i = 1; i <= w_max_used_index; i++) {
2580 if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) {
2581 sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name,
2583 witness_add_fullgraph(sb, &w_data[i]);
2589 * A simple hash function. Takes a key pointer and a key size. If size == 0,
2590 * interprets the key as a string and reads until the null
2591 * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit
2592 * hash value computed from the key.
2595 witness_hash_djb2(const uint8_t *key, uint32_t size)
2597 unsigned int hash = 5381;
2600 /* hash = hash * 33 + key[i] */
2602 for (i = 0; i < size; i++)
2603 hash = ((hash << 5) + hash) + (unsigned int)key[i];
2605 for (i = 0; key[i] != 0; i++)
2606 hash = ((hash << 5) + hash) + (unsigned int)key[i];
2613 * Initializes the two witness hash tables. Called exactly once from
2614 * witness_initialize().
2617 witness_init_hash_tables(void)
2621 MPASS(witness_cold);
2623 /* Initialize the hash tables. */
2624 for (i = 0; i < WITNESS_HASH_SIZE; i++)
2625 w_hash.wh_array[i] = NULL;
2627 w_hash.wh_size = WITNESS_HASH_SIZE;
2628 w_hash.wh_count = 0;
2630 /* Initialize the lock order data hash. */
2632 for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) {
2633 memset(&w_lodata[i], 0, sizeof(w_lodata[i]));
2634 w_lodata[i].wlod_next = w_lofree;
2635 w_lofree = &w_lodata[i];
2637 w_lohash.wloh_size = WITNESS_LO_HASH_SIZE;
2638 w_lohash.wloh_count = 0;
2639 for (i = 0; i < WITNESS_LO_HASH_SIZE; i++)
2640 w_lohash.wloh_array[i] = NULL;
2643 static struct witness *
2644 witness_hash_get(const char *key)
2650 if (witness_cold == 0)
2651 mtx_assert(&w_mtx, MA_OWNED);
2652 hash = witness_hash_djb2(key, 0) % w_hash.wh_size;
2653 w = w_hash.wh_array[hash];
2655 if (strcmp(w->w_name, key) == 0)
2665 witness_hash_put(struct witness *w)
2670 MPASS(w->w_name != NULL);
2671 if (witness_cold == 0)
2672 mtx_assert(&w_mtx, MA_OWNED);
2673 KASSERT(witness_hash_get(w->w_name) == NULL,
2674 ("%s: trying to add a hash entry that already exists!", __func__));
2675 KASSERT(w->w_hash_next == NULL,
2676 ("%s: w->w_hash_next != NULL", __func__));
2678 hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size;
2679 w->w_hash_next = w_hash.wh_array[hash];
2680 w_hash.wh_array[hash] = w;
2685 static struct witness_lock_order_data *
2686 witness_lock_order_get(struct witness *parent, struct witness *child)
2688 struct witness_lock_order_data *data = NULL;
2689 struct witness_lock_order_key key;
2692 MPASS(parent != NULL && child != NULL);
2693 key.from = parent->w_index;
2694 key.to = child->w_index;
2695 WITNESS_INDEX_ASSERT(key.from);
2696 WITNESS_INDEX_ASSERT(key.to);
2697 if ((w_rmatrix[parent->w_index][child->w_index]
2698 & WITNESS_LOCK_ORDER_KNOWN) == 0)
2701 hash = witness_hash_djb2((const char*)&key,
2702 sizeof(key)) % w_lohash.wloh_size;
2703 data = w_lohash.wloh_array[hash];
2704 while (data != NULL) {
2705 if (witness_lock_order_key_equal(&data->wlod_key, &key))
2707 data = data->wlod_next;
2715 * Verify that parent and child have a known relationship, are not the same,
2716 * and child is actually a child of parent. This is done without w_mtx
2717 * to avoid contention in the common case.
2720 witness_lock_order_check(struct witness *parent, struct witness *child)
2723 if (parent != child &&
2724 w_rmatrix[parent->w_index][child->w_index]
2725 & WITNESS_LOCK_ORDER_KNOWN &&
2726 isitmychild(parent, child))
2733 witness_lock_order_add(struct witness *parent, struct witness *child)
2735 struct witness_lock_order_data *data = NULL;
2736 struct witness_lock_order_key key;
2739 MPASS(parent != NULL && child != NULL);
2740 key.from = parent->w_index;
2741 key.to = child->w_index;
2742 WITNESS_INDEX_ASSERT(key.from);
2743 WITNESS_INDEX_ASSERT(key.to);
2744 if (w_rmatrix[parent->w_index][child->w_index]
2745 & WITNESS_LOCK_ORDER_KNOWN)
2748 hash = witness_hash_djb2((const char*)&key,
2749 sizeof(key)) % w_lohash.wloh_size;
2750 w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN;
2754 w_lofree = data->wlod_next;
2755 data->wlod_next = w_lohash.wloh_array[hash];
2756 data->wlod_key = key;
2757 w_lohash.wloh_array[hash] = data;
2758 w_lohash.wloh_count++;
2759 stack_zero(&data->wlod_stack);
2760 stack_save(&data->wlod_stack);
2764 /* Call this whenver the structure of the witness graph changes. */
2766 witness_increment_graph_generation(void)
2769 if (witness_cold == 0)
2770 mtx_assert(&w_mtx, MA_OWNED);
2776 _witness_debugger(int cond, const char *msg)
2779 if (witness_trace && cond)
2781 if (witness_kdb && cond)
2782 kdb_enter(KDB_WHY_WITNESS, msg);