/*- * Copyright (c) 2008 Isilon Systems, Inc. * Copyright (c) 2008 Ilya Maykov * Copyright (c) 1998 Berkeley Software Design, Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Berkeley Software Design Inc's name may not be used to endorse or * promote products derived from this software without specific prior * written permission. * * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $ * and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $ */ /* * Implementation of the `witness' lock verifier. Originally implemented for * mutexes in BSD/OS. Extended to handle generic lock objects and lock * classes in FreeBSD. */ /* * Main Entry: witness * Pronunciation: 'wit-n&s * Function: noun * Etymology: Middle English witnesse, from Old English witnes knowledge, * testimony, witness, from 2wit * Date: before 12th century * 1 : attestation of a fact or event : TESTIMONY * 2 : one that gives evidence; specifically : one who testifies in * a cause or before a judicial tribunal * 3 : one asked to be present at a transaction so as to be able to * testify to its having taken place * 4 : one who has personal knowledge of something * 5 a : something serving as evidence or proof : SIGN * b : public affirmation by word or example of usually * religious faith or conviction * 6 capitalized : a member of the Jehovah's Witnesses */ /* * Special rules concerning Giant and lock orders: * * 1) Giant must be acquired before any other mutexes. Stated another way, * no other mutex may be held when Giant is acquired. * * 2) Giant must be released when blocking on a sleepable lock. * * This rule is less obvious, but is a result of Giant providing the same * semantics as spl(). Basically, when a thread sleeps, it must release * Giant. When a thread blocks on a sleepable lock, it sleeps. Hence rule * 2). * * 3) Giant may be acquired before or after sleepable locks. * * This rule is also not quite as obvious. Giant may be acquired after * a sleepable lock because it is a non-sleepable lock and non-sleepable * locks may always be acquired while holding a sleepable lock. The second * case, Giant before a sleepable lock, follows from rule 2) above. Suppose * you have two threads T1 and T2 and a sleepable lock X. Suppose that T1 * acquires X and blocks on Giant. Then suppose that T2 acquires Giant and * blocks on X. When T2 blocks on X, T2 will release Giant allowing T1 to * execute. Thus, acquiring Giant both before and after a sleepable lock * will not result in a lock order reversal. */ #include __FBSDID("$FreeBSD$"); #include "opt_ddb.h" #include "opt_hwpmc_hooks.h" #include "opt_stack.h" #include "opt_witness.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #ifdef DDB #include #endif #include #if !defined(DDB) && !defined(STACK) #error "DDB or STACK options are required for WITNESS" #endif /* Note that these traces do not work with KTR_ALQ. */ #if 0 #define KTR_WITNESS KTR_SUBSYS #else #define KTR_WITNESS 0 #endif #define LI_RECURSEMASK 0x0000ffff /* Recursion depth of lock instance. */ #define LI_EXCLUSIVE 0x00010000 /* Exclusive lock instance. */ /* Define this to check for blessed mutexes */ #undef BLESSING #define WITNESS_COUNT 1024 #define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4) #define WITNESS_HASH_SIZE 251 /* Prime, gives load factor < 2 */ #define WITNESS_PENDLIST 512 /* Allocate 256 KB of stack data space */ #define WITNESS_LO_DATA_COUNT 2048 /* Prime, gives load factor of ~2 at full load */ #define WITNESS_LO_HASH_SIZE 1021 /* * XXX: This is somewhat bogus, as we assume here that at most 2048 threads * will hold LOCK_NCHILDREN locks. We handle failure ok, and we should * probably be safe for the most part, but it's still a SWAG. */ #define LOCK_NCHILDREN 5 #define LOCK_CHILDCOUNT 2048 #define MAX_W_NAME 64 #define BADSTACK_SBUF_SIZE (256 * WITNESS_COUNT) #define CYCLEGRAPH_SBUF_SIZE 8192 #define FULLGRAPH_SBUF_SIZE 32768 /* * These flags go in the witness relationship matrix and describe the * relationship between any two struct witness objects. */ #define WITNESS_UNRELATED 0x00 /* No lock order relation. */ #define WITNESS_PARENT 0x01 /* Parent, aka direct ancestor. */ #define WITNESS_ANCESTOR 0x02 /* Direct or indirect ancestor. */ #define WITNESS_CHILD 0x04 /* Child, aka direct descendant. */ #define WITNESS_DESCENDANT 0x08 /* Direct or indirect descendant. */ #define WITNESS_ANCESTOR_MASK (WITNESS_PARENT | WITNESS_ANCESTOR) #define WITNESS_DESCENDANT_MASK (WITNESS_CHILD | WITNESS_DESCENDANT) #define WITNESS_RELATED_MASK \ (WITNESS_ANCESTOR_MASK | WITNESS_DESCENDANT_MASK) #define WITNESS_REVERSAL 0x10 /* A lock order reversal has been * observed. */ #define WITNESS_RESERVED1 0x20 /* Unused flag, reserved. */ #define WITNESS_RESERVED2 0x40 /* Unused flag, reserved. */ #define WITNESS_LOCK_ORDER_KNOWN 0x80 /* This lock order is known. */ /* Descendant to ancestor flags */ #define WITNESS_DTOA(x) (((x) & WITNESS_RELATED_MASK) >> 2) /* Ancestor to descendant flags */ #define WITNESS_ATOD(x) (((x) & WITNESS_RELATED_MASK) << 2) #define WITNESS_INDEX_ASSERT(i) \ MPASS((i) > 0 && (i) <= w_max_used_index && (i) < WITNESS_COUNT) MALLOC_DEFINE(M_WITNESS, "Witness", "Witness"); /* * Lock instances. A lock instance is the data associated with a lock while * it is held by witness. For example, a lock instance will hold the * recursion count of a lock. Lock instances are held in lists. Spin locks * are held in a per-cpu list while sleep locks are held in per-thread list. */ struct lock_instance { struct lock_object *li_lock; const char *li_file; int li_line; u_int li_flags; }; /* * A simple list type used to build the list of locks held by a thread * or CPU. We can't simply embed the list in struct lock_object since a * lock may be held by more than one thread if it is a shared lock. Locks * are added to the head of the list, so we fill up each list entry from * "the back" logically. To ease some of the arithmetic, we actually fill * in each list entry the normal way (children[0] then children[1], etc.) but * when we traverse the list we read children[count-1] as the first entry * down to children[0] as the final entry. */ struct lock_list_entry { struct lock_list_entry *ll_next; struct lock_instance ll_children[LOCK_NCHILDREN]; u_int ll_count; }; /* * The main witness structure. One of these per named lock type in the system * (for example, "vnode interlock"). */ struct witness { char w_name[MAX_W_NAME]; uint32_t w_index; /* Index in the relationship matrix */ struct lock_class *w_class; STAILQ_ENTRY(witness) w_list; /* List of all witnesses. */ STAILQ_ENTRY(witness) w_typelist; /* Witnesses of a type. */ struct witness *w_hash_next; /* Linked list in hash buckets. */ const char *w_file; /* File where last acquired */ uint32_t w_line; /* Line where last acquired */ uint32_t w_refcount; uint16_t w_num_ancestors; /* direct/indirect * ancestor count */ uint16_t w_num_descendants; /* direct/indirect * descendant count */ int16_t w_ddb_level; int w_displayed:1; int w_reversed:1; }; STAILQ_HEAD(witness_list, witness); /* * The witness hash table. Keys are witness names (const char *), elements are * witness objects (struct witness *). */ struct witness_hash { struct witness *wh_array[WITNESS_HASH_SIZE]; uint32_t wh_size; uint32_t wh_count; }; /* * Key type for the lock order data hash table. */ struct witness_lock_order_key { uint16_t from; uint16_t to; }; struct witness_lock_order_data { struct stack wlod_stack; struct witness_lock_order_key wlod_key; struct witness_lock_order_data *wlod_next; }; /* * The witness lock order data hash table. Keys are witness index tuples * (struct witness_lock_order_key), elements are lock order data objects * (struct witness_lock_order_data). */ struct witness_lock_order_hash { struct witness_lock_order_data *wloh_array[WITNESS_LO_HASH_SIZE]; u_int wloh_size; u_int wloh_count; }; #ifdef BLESSING struct witness_blessed { const char *b_lock1; const char *b_lock2; }; #endif struct witness_pendhelp { const char *wh_type; struct lock_object *wh_lock; }; struct witness_order_list_entry { const char *w_name; struct lock_class *w_class; }; /* * Returns 0 if one of the locks is a spin lock and the other is not. * Returns 1 otherwise. */ static __inline int witness_lock_type_equal(struct witness *w1, struct witness *w2) { return ((w1->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) == (w2->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))); } static __inline int witness_lock_order_key_empty(const struct witness_lock_order_key *key) { return (key->from == 0 && key->to == 0); } static __inline int witness_lock_order_key_equal(const struct witness_lock_order_key *a, const struct witness_lock_order_key *b) { return (a->from == b->from && a->to == b->to); } static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname); #ifdef KDB static void _witness_debugger(int cond, const char *msg); #endif static void adopt(struct witness *parent, struct witness *child); #ifdef BLESSING static int blessed(struct witness *, struct witness *); #endif static void depart(struct witness *w); static struct witness *enroll(const char *description, struct lock_class *lock_class); static struct lock_instance *find_instance(struct lock_list_entry *list, struct lock_object *lock); static int isitmychild(struct witness *parent, struct witness *child); static int isitmydescendant(struct witness *parent, struct witness *child); static void itismychild(struct witness *parent, struct witness *child); static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS); static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS); static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS); static void witness_add_fullgraph(struct sbuf *sb, struct witness *parent); #ifdef DDB static void witness_ddb_compute_levels(void); static void witness_ddb_display(void(*)(const char *fmt, ...)); static void witness_ddb_display_descendants(void(*)(const char *fmt, ...), struct witness *, int indent); static void witness_ddb_display_list(void(*prnt)(const char *fmt, ...), struct witness_list *list); static void witness_ddb_level_descendants(struct witness *parent, int l); static void witness_ddb_list(struct thread *td); #endif static void witness_free(struct witness *m); static struct witness *witness_get(void); static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size); static struct witness *witness_hash_get(const char *key); static void witness_hash_put(struct witness *w); static void witness_init_hash_tables(void); static void witness_increment_graph_generation(void); static void witness_lock_list_free(struct lock_list_entry *lle); static struct lock_list_entry *witness_lock_list_get(void); static int witness_lock_order_add(struct witness *parent, struct witness *child); static int witness_lock_order_check(struct witness *parent, struct witness *child); static struct witness_lock_order_data *witness_lock_order_get( struct witness *parent, struct witness *child); static void witness_list_lock(struct lock_instance *instance); #ifdef KDB #define witness_debugger(c) _witness_debugger(c, __func__) #else #define witness_debugger(c) #endif SYSCTL_NODE(_debug, OID_AUTO, witness, CTLFLAG_RW, 0, "Witness Locking"); /* * If set to 0, lock order checking is disabled. If set to -1, * witness is completely disabled. Otherwise witness performs full * lock order checking for all locks. At runtime, lock order checking * may be toggled. However, witness cannot be reenabled once it is * completely disabled. */ static int witness_watch = 1; TUNABLE_INT("debug.witness.watch", &witness_watch); SYSCTL_PROC(_debug_witness, OID_AUTO, watch, CTLFLAG_RW | CTLTYPE_INT, NULL, 0, sysctl_debug_witness_watch, "I", "witness is watching lock operations"); #ifdef KDB /* * When KDB is enabled and witness_kdb is 1, it will cause the system * to drop into kdebug() when: * - a lock hierarchy violation occurs * - locks are held when going to sleep. */ #ifdef WITNESS_KDB int witness_kdb = 1; #else int witness_kdb = 0; #endif TUNABLE_INT("debug.witness.kdb", &witness_kdb); SYSCTL_INT(_debug_witness, OID_AUTO, kdb, CTLFLAG_RW, &witness_kdb, 0, ""); /* * When KDB is enabled and witness_trace is 1, it will cause the system * to print a stack trace: * - a lock hierarchy violation occurs * - locks are held when going to sleep. */ int witness_trace = 1; TUNABLE_INT("debug.witness.trace", &witness_trace); SYSCTL_INT(_debug_witness, OID_AUTO, trace, CTLFLAG_RW, &witness_trace, 0, ""); #endif /* KDB */ #ifdef WITNESS_SKIPSPIN int witness_skipspin = 1; #else int witness_skipspin = 0; #endif TUNABLE_INT("debug.witness.skipspin", &witness_skipspin); SYSCTL_INT(_debug_witness, OID_AUTO, skipspin, CTLFLAG_RDTUN, &witness_skipspin, 0, ""); /* * Call this to print out the relations between locks. */ SYSCTL_PROC(_debug_witness, OID_AUTO, fullgraph, CTLTYPE_STRING | CTLFLAG_RD, NULL, 0, sysctl_debug_witness_fullgraph, "A", "Show locks relation graphs"); /* * Call this to print out the witness faulty stacks. */ SYSCTL_PROC(_debug_witness, OID_AUTO, badstacks, CTLTYPE_STRING | CTLFLAG_RD, NULL, 0, sysctl_debug_witness_badstacks, "A", "Show bad witness stacks"); static struct mtx w_mtx; /* w_list */ static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); /* w_typelist */ static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); /* lock list */ static struct lock_list_entry *w_lock_list_free = NULL; static struct witness_pendhelp pending_locks[WITNESS_PENDLIST]; static u_int pending_cnt; static int w_free_cnt, w_spin_cnt, w_sleep_cnt; SYSCTL_INT(_debug_witness, OID_AUTO, free_cnt, CTLFLAG_RD, &w_free_cnt, 0, ""); SYSCTL_INT(_debug_witness, OID_AUTO, spin_cnt, CTLFLAG_RD, &w_spin_cnt, 0, ""); SYSCTL_INT(_debug_witness, OID_AUTO, sleep_cnt, CTLFLAG_RD, &w_sleep_cnt, 0, ""); static struct witness *w_data; static uint8_t w_rmatrix[WITNESS_COUNT+1][WITNESS_COUNT+1]; static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; static struct witness_hash w_hash; /* The witness hash table. */ /* The lock order data hash */ static struct witness_lock_order_data w_lodata[WITNESS_LO_DATA_COUNT]; static struct witness_lock_order_data *w_lofree = NULL; static struct witness_lock_order_hash w_lohash; static int w_max_used_index = 0; static unsigned int w_generation = 0; static const char *w_notrunning = "Witness not running\n"; static const char *w_stillcold = "Witness is still cold\n"; static struct witness_order_list_entry order_lists[] = { /* * sx locks */ { "proctree", &lock_class_sx }, { "allproc", &lock_class_sx }, { "allprison", &lock_class_sx }, { NULL, NULL }, /* * Various mutexes */ { "Giant", &lock_class_mtx_sleep }, { "pipe mutex", &lock_class_mtx_sleep }, { "sigio lock", &lock_class_mtx_sleep }, { "process group", &lock_class_mtx_sleep }, { "process lock", &lock_class_mtx_sleep }, { "session", &lock_class_mtx_sleep }, { "uidinfo hash", &lock_class_rw }, #ifdef HWPMC_HOOKS { "pmc-sleep", &lock_class_mtx_sleep }, #endif { NULL, NULL }, /* * Sockets */ { "accept", &lock_class_mtx_sleep }, { "so_snd", &lock_class_mtx_sleep }, { "so_rcv", &lock_class_mtx_sleep }, { "sellck", &lock_class_mtx_sleep }, { NULL, NULL }, /* * Routing */ { "so_rcv", &lock_class_mtx_sleep }, { "radix node head", &lock_class_rw }, { "rtentry", &lock_class_mtx_sleep }, { "ifaddr", &lock_class_mtx_sleep }, { NULL, NULL }, /* * Multicast - protocol locks before interface locks, after UDP locks. */ { "udpinp", &lock_class_rw }, { "in_multi_mtx", &lock_class_mtx_sleep }, { "igmp_mtx", &lock_class_mtx_sleep }, { "if_addr_mtx", &lock_class_mtx_sleep }, { NULL, NULL }, /* * UNIX Domain Sockets */ { "unp", &lock_class_mtx_sleep }, { "so_snd", &lock_class_mtx_sleep }, { NULL, NULL }, /* * UDP/IP */ { "udp", &lock_class_rw }, { "udpinp", &lock_class_rw }, { "so_snd", &lock_class_mtx_sleep }, { NULL, NULL }, /* * TCP/IP */ { "tcp", &lock_class_rw }, { "tcpinp", &lock_class_rw }, { "so_snd", &lock_class_mtx_sleep }, { NULL, NULL }, /* * SLIP */ { "slip_mtx", &lock_class_mtx_sleep }, { "slip sc_mtx", &lock_class_mtx_sleep }, { NULL, NULL }, /* * netatalk */ { "ddp_list_mtx", &lock_class_mtx_sleep }, { "ddp_mtx", &lock_class_mtx_sleep }, { NULL, NULL }, /* * BPF */ { "bpf global lock", &lock_class_mtx_sleep }, { "bpf interface lock", &lock_class_mtx_sleep }, { "bpf cdev lock", &lock_class_mtx_sleep }, { NULL, NULL }, /* * NFS server */ { "nfsd_mtx", &lock_class_mtx_sleep }, { "so_snd", &lock_class_mtx_sleep }, { NULL, NULL }, /* * IEEE 802.11 */ { "802.11 com lock", &lock_class_mtx_sleep}, { NULL, NULL }, /* * Network drivers */ { "network driver", &lock_class_mtx_sleep}, { NULL, NULL }, /* * Netgraph */ { "ng_node", &lock_class_mtx_sleep }, { "ng_worklist", &lock_class_mtx_sleep }, { NULL, NULL }, /* * CDEV */ { "system map", &lock_class_mtx_sleep }, { "vm page queue mutex", &lock_class_mtx_sleep }, { "vnode interlock", &lock_class_mtx_sleep }, { "cdev", &lock_class_mtx_sleep }, { NULL, NULL }, /* * kqueue/VFS interaction */ { "kqueue", &lock_class_mtx_sleep }, { "struct mount mtx", &lock_class_mtx_sleep }, { "vnode interlock", &lock_class_mtx_sleep }, { NULL, NULL }, /* * spin locks */ #ifdef SMP { "ap boot", &lock_class_mtx_spin }, #endif { "rm.mutex_mtx", &lock_class_mtx_spin }, { "sio", &lock_class_mtx_spin }, { "scrlock", &lock_class_mtx_spin }, #ifdef __i386__ { "cy", &lock_class_mtx_spin }, #endif #ifdef __sparc64__ { "pcib_mtx", &lock_class_mtx_spin }, { "rtc_mtx", &lock_class_mtx_spin }, #endif { "scc_hwmtx", &lock_class_mtx_spin }, { "uart_hwmtx", &lock_class_mtx_spin }, { "fast_taskqueue", &lock_class_mtx_spin }, { "intr table", &lock_class_mtx_spin }, #ifdef HWPMC_HOOKS { "pmc-per-proc", &lock_class_mtx_spin }, #endif { "process slock", &lock_class_mtx_spin }, { "sleepq chain", &lock_class_mtx_spin }, { "umtx lock", &lock_class_mtx_spin }, { "rm_spinlock", &lock_class_mtx_spin }, { "turnstile chain", &lock_class_mtx_spin }, { "turnstile lock", &lock_class_mtx_spin }, { "sched lock", &lock_class_mtx_spin }, { "td_contested", &lock_class_mtx_spin }, { "callout", &lock_class_mtx_spin }, { "entropy harvest mutex", &lock_class_mtx_spin }, { "syscons video lock", &lock_class_mtx_spin }, { "time lock", &lock_class_mtx_spin }, #ifdef SMP { "smp rendezvous", &lock_class_mtx_spin }, #endif #ifdef __powerpc__ { "tlb0", &lock_class_mtx_spin }, #endif /* * leaf locks */ { "intrcnt", &lock_class_mtx_spin }, { "icu", &lock_class_mtx_spin }, #if defined(SMP) && defined(__sparc64__) { "ipi", &lock_class_mtx_spin }, #endif #ifdef __i386__ { "allpmaps", &lock_class_mtx_spin }, { "descriptor tables", &lock_class_mtx_spin }, #endif { "clk", &lock_class_mtx_spin }, { "cpuset", &lock_class_mtx_spin }, { "mprof lock", &lock_class_mtx_spin }, { "zombie lock", &lock_class_mtx_spin }, { "ALD Queue", &lock_class_mtx_spin }, #ifdef __ia64__ { "MCA spin lock", &lock_class_mtx_spin }, #endif #if defined(__i386__) || defined(__amd64__) { "pcicfg", &lock_class_mtx_spin }, { "NDIS thread lock", &lock_class_mtx_spin }, #endif { "tw_osl_io_lock", &lock_class_mtx_spin }, { "tw_osl_q_lock", &lock_class_mtx_spin }, { "tw_cl_io_lock", &lock_class_mtx_spin }, { "tw_cl_intr_lock", &lock_class_mtx_spin }, { "tw_cl_gen_lock", &lock_class_mtx_spin }, #ifdef HWPMC_HOOKS { "pmc-leaf", &lock_class_mtx_spin }, #endif { "blocked lock", &lock_class_mtx_spin }, { NULL, NULL }, { NULL, NULL } }; #ifdef BLESSING /* * Pairs of locks which have been blessed * Don't complain about order problems with blessed locks */ static struct witness_blessed blessed_list[] = { }; static int blessed_count = sizeof(blessed_list) / sizeof(struct witness_blessed); #endif /* * This global is set to 0 once it becomes safe to use the witness code. */ static int witness_cold = 1; /* * This global is set to 1 once the static lock orders have been enrolled * so that a warning can be issued for any spin locks enrolled later. */ static int witness_spin_warn = 0; /* * The WITNESS-enabled diagnostic code. Note that the witness code does * assume that the early boot is single-threaded at least until after this * routine is completed. */ static void witness_initialize(void *dummy __unused) { struct lock_object *lock; struct witness_order_list_entry *order; struct witness *w, *w1; int i; w_data = malloc(sizeof (struct witness) * WITNESS_COUNT, M_WITNESS, M_NOWAIT | M_ZERO); /* * We have to release Giant before initializing its witness * structure so that WITNESS doesn't get confused. */ mtx_unlock(&Giant); mtx_assert(&Giant, MA_NOTOWNED); CTR1(KTR_WITNESS, "%s: initializing witness", __func__); mtx_init(&w_mtx, "witness lock", NULL, MTX_SPIN | MTX_QUIET | MTX_NOWITNESS | MTX_NOPROFILE); for (i = WITNESS_COUNT - 1; i >= 0; i--) { w = &w_data[i]; memset(w, 0, sizeof(*w)); w_data[i].w_index = i; /* Witness index never changes. */ witness_free(w); } KASSERT(STAILQ_FIRST(&w_free)->w_index == 0, ("%s: Invalid list of free witness objects", __func__)); /* Witness with index 0 is not used to aid in debugging. */ STAILQ_REMOVE_HEAD(&w_free, w_list); w_free_cnt--; memset(w_rmatrix, 0, (sizeof(**w_rmatrix) * (WITNESS_COUNT+1) * (WITNESS_COUNT+1))); for (i = 0; i < LOCK_CHILDCOUNT; i++) witness_lock_list_free(&w_locklistdata[i]); witness_init_hash_tables(); /* First add in all the specified order lists. */ for (order = order_lists; order->w_name != NULL; order++) { w = enroll(order->w_name, order->w_class); if (w == NULL) continue; w->w_file = "order list"; for (order++; order->w_name != NULL; order++) { w1 = enroll(order->w_name, order->w_class); if (w1 == NULL) continue; w1->w_file = "order list"; itismychild(w, w1); w = w1; } } witness_spin_warn = 1; /* Iterate through all locks and add them to witness. */ for (i = 0; pending_locks[i].wh_lock != NULL; i++) { lock = pending_locks[i].wh_lock; KASSERT(lock->lo_flags & LO_WITNESS, ("%s: lock %s is on pending list but not LO_WITNESS", __func__, lock->lo_name)); lock->lo_witness = enroll(pending_locks[i].wh_type, LOCK_CLASS(lock)); } /* Mark the witness code as being ready for use. */ witness_cold = 0; mtx_lock(&Giant); } SYSINIT(witness_init, SI_SUB_WITNESS, SI_ORDER_FIRST, witness_initialize, NULL); void witness_init(struct lock_object *lock, const char *type) { struct lock_class *class; /* Various sanity checks. */ class = LOCK_CLASS(lock); if ((lock->lo_flags & LO_RECURSABLE) != 0 && (class->lc_flags & LC_RECURSABLE) == 0) panic("%s: lock (%s) %s can not be recursable", __func__, class->lc_name, lock->lo_name); if ((lock->lo_flags & LO_SLEEPABLE) != 0 && (class->lc_flags & LC_SLEEPABLE) == 0) panic("%s: lock (%s) %s can not be sleepable", __func__, class->lc_name, lock->lo_name); if ((lock->lo_flags & LO_UPGRADABLE) != 0 && (class->lc_flags & LC_UPGRADABLE) == 0) panic("%s: lock (%s) %s can not be upgradable", __func__, class->lc_name, lock->lo_name); /* * If we shouldn't watch this lock, then just clear lo_witness. * Otherwise, if witness_cold is set, then it is too early to * enroll this lock, so defer it to witness_initialize() by adding * it to the pending_locks list. If it is not too early, then enroll * the lock now. */ if (witness_watch < 1 || panicstr != NULL || (lock->lo_flags & LO_WITNESS) == 0) lock->lo_witness = NULL; else if (witness_cold) { pending_locks[pending_cnt].wh_lock = lock; pending_locks[pending_cnt++].wh_type = type; if (pending_cnt > WITNESS_PENDLIST) panic("%s: pending locks list is too small, bump it\n", __func__); } else lock->lo_witness = enroll(type, class); } void witness_destroy(struct lock_object *lock) { struct lock_class *class; struct witness *w; class = LOCK_CLASS(lock); if (witness_cold) panic("lock (%s) %s destroyed while witness_cold", class->lc_name, lock->lo_name); /* XXX: need to verify that no one holds the lock */ if ((lock->lo_flags & LO_WITNESS) == 0 || lock->lo_witness == NULL) return; w = lock->lo_witness; mtx_lock_spin(&w_mtx); MPASS(w->w_refcount > 0); w->w_refcount--; if (w->w_refcount == 0) depart(w); mtx_unlock_spin(&w_mtx); } #ifdef DDB static void witness_ddb_compute_levels(void) { struct witness *w; /* * First clear all levels. */ STAILQ_FOREACH(w, &w_all, w_list) w->w_ddb_level = -1; /* * Look for locks with no parents and level all their descendants. */ STAILQ_FOREACH(w, &w_all, w_list) { /* If the witness has ancestors (is not a root), skip it. */ if (w->w_num_ancestors > 0) continue; witness_ddb_level_descendants(w, 0); } } static void witness_ddb_level_descendants(struct witness *w, int l) { int i; if (w->w_ddb_level >= l) return; w->w_ddb_level = l; l++; for (i = 1; i <= w_max_used_index; i++) { if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) witness_ddb_level_descendants(&w_data[i], l); } } static void witness_ddb_display_descendants(void(*prnt)(const char *fmt, ...), struct witness *w, int indent) { int i; for (i = 0; i < indent; i++) prnt(" "); prnt("%s (type: %s, depth: %d, active refs: %d)", w->w_name, w->w_class->lc_name, w->w_ddb_level, w->w_refcount); if (w->w_displayed) { prnt(" -- (already displayed)\n"); return; } w->w_displayed = 1; if (w->w_file != NULL && w->w_line != 0) prnt(" -- last acquired @ %s:%d\n", w->w_file, w->w_line); else prnt(" -- never acquired\n"); indent++; WITNESS_INDEX_ASSERT(w->w_index); for (i = 1; i <= w_max_used_index; i++) { if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) witness_ddb_display_descendants(prnt, &w_data[i], indent); } } static void witness_ddb_display_list(void(*prnt)(const char *fmt, ...), struct witness_list *list) { struct witness *w; STAILQ_FOREACH(w, list, w_typelist) { if (w->w_file == NULL || w->w_ddb_level > 0) continue; /* This lock has no anscestors - display its descendants. */ witness_ddb_display_descendants(prnt, w, 0); } } static void witness_ddb_display(void(*prnt)(const char *fmt, ...)) { struct witness *w; KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); witness_ddb_compute_levels(); /* Clear all the displayed flags. */ STAILQ_FOREACH(w, &w_all, w_list) w->w_displayed = 0; /* * First, handle sleep locks which have been acquired at least * once. */ prnt("Sleep locks:\n"); witness_ddb_display_list(prnt, &w_sleep); /* * Now do spin locks which have been acquired at least once. */ prnt("\nSpin locks:\n"); witness_ddb_display_list(prnt, &w_spin); /* * Finally, any locks which have not been acquired yet. */ prnt("\nLocks which were never acquired:\n"); STAILQ_FOREACH(w, &w_all, w_list) { if (w->w_file != NULL || w->w_refcount == 0) continue; prnt("%s (type: %s, depth: %d)\n", w->w_name, w->w_class->lc_name, w->w_ddb_level); } } #endif /* DDB */ /* Trim useless garbage from filenames. */ static const char * fixup_filename(const char *file) { if (file == NULL) return (NULL); while (strncmp(file, "../", 3) == 0) file += 3; return (file); } int witness_defineorder(struct lock_object *lock1, struct lock_object *lock2) { if (witness_watch == -1 || panicstr != NULL) return (0); /* Require locks that witness knows about. */ if (lock1 == NULL || lock1->lo_witness == NULL || lock2 == NULL || lock2->lo_witness == NULL) return (EINVAL); mtx_assert(&w_mtx, MA_NOTOWNED); mtx_lock_spin(&w_mtx); /* * If we already have either an explicit or implied lock order that * is the other way around, then return an error. */ if (witness_watch && isitmydescendant(lock2->lo_witness, lock1->lo_witness)) { mtx_unlock_spin(&w_mtx); return (EDOOFUS); } /* Try to add the new order. */ CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, lock2->lo_witness->w_name, lock1->lo_witness->w_name); itismychild(lock1->lo_witness, lock2->lo_witness); mtx_unlock_spin(&w_mtx); return (0); } void witness_checkorder(struct lock_object *lock, int flags, const char *file, int line, struct lock_object *interlock) { struct lock_list_entry *lock_list, *lle; struct lock_instance *lock1, *lock2, *plock; struct lock_class *class; struct witness *w, *w1; struct thread *td; int i, j; if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL || panicstr != NULL) return; w = lock->lo_witness; class = LOCK_CLASS(lock); td = curthread; file = fixup_filename(file); if (class->lc_flags & LC_SLEEPLOCK) { /* * Since spin locks include a critical section, this check * implicitly enforces a lock order of all sleep locks before * all spin locks. */ if (td->td_critnest != 0 && !kdb_active) panic("blockable sleep lock (%s) %s @ %s:%d", class->lc_name, lock->lo_name, file, line); /* * If this is the first lock acquired then just return as * no order checking is needed. */ lock_list = td->td_sleeplocks; if (lock_list == NULL || lock_list->ll_count == 0) return; } else { /* * If this is the first lock, just return as no order * checking is needed. Avoid problems with thread * migration pinning the thread while checking if * spinlocks are held. If at least one spinlock is held * the thread is in a safe path and it is allowed to * unpin it. */ sched_pin(); lock_list = PCPU_GET(spinlocks); if (lock_list == NULL || lock_list->ll_count == 0) { sched_unpin(); return; } sched_unpin(); } /* * Check to see if we are recursing on a lock we already own. If * so, make sure that we don't mismatch exclusive and shared lock * acquires. */ lock1 = find_instance(lock_list, lock); if (lock1 != NULL) { if ((lock1->li_flags & LI_EXCLUSIVE) != 0 && (flags & LOP_EXCLUSIVE) == 0) { printf("shared lock of (%s) %s @ %s:%d\n", class->lc_name, lock->lo_name, file, line); printf("while exclusively locked from %s:%d\n", lock1->li_file, lock1->li_line); panic("share->excl"); } if ((lock1->li_flags & LI_EXCLUSIVE) == 0 && (flags & LOP_EXCLUSIVE) != 0) { printf("exclusive lock of (%s) %s @ %s:%d\n", class->lc_name, lock->lo_name, file, line); printf("while share locked from %s:%d\n", lock1->li_file, lock1->li_line); panic("excl->share"); } return; } /* * Find the previously acquired lock, but ignore interlocks. */ plock = &lock_list->ll_children[lock_list->ll_count - 1]; if (interlock != NULL && plock->li_lock == interlock) { if (lock_list->ll_count > 1) plock = &lock_list->ll_children[lock_list->ll_count - 2]; else { lle = lock_list->ll_next; /* * The interlock is the only lock we hold, so * simply return. */ if (lle == NULL) return; plock = &lle->ll_children[lle->ll_count - 1]; } } /* * Try to perform most checks without a lock. If this succeeds we * can skip acquiring the lock and return success. */ w1 = plock->li_lock->lo_witness; if (witness_lock_order_check(w1, w)) return; /* * Check for duplicate locks of the same type. Note that we only * have to check for this on the last lock we just acquired. Any * other cases will be caught as lock order violations. */ mtx_lock_spin(&w_mtx); witness_lock_order_add(w1, w); if (w1 == w) { i = w->w_index; if (!(lock->lo_flags & LO_DUPOK) && !(flags & LOP_DUPOK) && !(w_rmatrix[i][i] & WITNESS_REVERSAL)) { w_rmatrix[i][i] |= WITNESS_REVERSAL; w->w_reversed = 1; mtx_unlock_spin(&w_mtx); printf( "acquiring duplicate lock of same type: \"%s\"\n", w->w_name); printf(" 1st %s @ %s:%d\n", plock->li_lock->lo_name, plock->li_file, plock->li_line); printf(" 2nd %s @ %s:%d\n", lock->lo_name, file, line); witness_debugger(1); } else mtx_unlock_spin(&w_mtx); return; } mtx_assert(&w_mtx, MA_OWNED); /* * If we know that the the lock we are acquiring comes after * the lock we most recently acquired in the lock order tree, * then there is no need for any further checks. */ if (isitmychild(w1, w)) goto out; for (j = 0, lle = lock_list; lle != NULL; lle = lle->ll_next) { for (i = lle->ll_count - 1; i >= 0; i--, j++) { MPASS(j < WITNESS_COUNT); lock1 = &lle->ll_children[i]; /* * Ignore the interlock the first time we see it. */ if (interlock != NULL && interlock == lock1->li_lock) { interlock = NULL; continue; } /* * If this lock doesn't undergo witness checking, * then skip it. */ w1 = lock1->li_lock->lo_witness; if (w1 == NULL) { KASSERT((lock1->li_lock->lo_flags & LO_WITNESS) == 0, ("lock missing witness structure")); continue; } /* * If we are locking Giant and this is a sleepable * lock, then skip it. */ if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0 && lock == &Giant.lock_object) continue; /* * If we are locking a sleepable lock and this lock * is Giant, then skip it. */ if ((lock->lo_flags & LO_SLEEPABLE) != 0 && lock1->li_lock == &Giant.lock_object) continue; /* * If we are locking a sleepable lock and this lock * isn't sleepable, we want to treat it as a lock * order violation to enfore a general lock order of * sleepable locks before non-sleepable locks. */ if (((lock->lo_flags & LO_SLEEPABLE) != 0 && (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) goto reversal; /* * If we are locking Giant and this is a non-sleepable * lock, then treat it as a reversal. */ if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && lock == &Giant.lock_object) goto reversal; /* * Check the lock order hierarchy for a reveresal. */ if (!isitmydescendant(w, w1)) continue; reversal: /* * We have a lock order violation, check to see if it * is allowed or has already been yelled about. */ #ifdef BLESSING /* * If the lock order is blessed, just bail. We don't * look for other lock order violations though, which * may be a bug. */ if (blessed(w, w1)) goto out; #endif /* Bail if this violation is known */ if (w_rmatrix[w1->w_index][w->w_index] & WITNESS_REVERSAL) goto out; /* Record this as a violation */ w_rmatrix[w1->w_index][w->w_index] |= WITNESS_REVERSAL; w_rmatrix[w->w_index][w1->w_index] |= WITNESS_REVERSAL; w->w_reversed = w1->w_reversed = 1; witness_increment_graph_generation(); mtx_unlock_spin(&w_mtx); /* * Ok, yell about it. */ if (((lock->lo_flags & LO_SLEEPABLE) != 0 && (lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0)) printf( "lock order reversal: (sleepable after non-sleepable)\n"); else if ((lock1->li_lock->lo_flags & LO_SLEEPABLE) == 0 && lock == &Giant.lock_object) printf( "lock order reversal: (Giant after non-sleepable)\n"); else printf("lock order reversal:\n"); /* * Try to locate an earlier lock with * witness w in our list. */ do { lock2 = &lle->ll_children[i]; MPASS(lock2->li_lock != NULL); if (lock2->li_lock->lo_witness == w) break; if (i == 0 && lle->ll_next != NULL) { lle = lle->ll_next; i = lle->ll_count - 1; MPASS(i >= 0 && i < LOCK_NCHILDREN); } else i--; } while (i >= 0); if (i < 0) { printf(" 1st %p %s (%s) @ %s:%d\n", lock1->li_lock, lock1->li_lock->lo_name, w1->w_name, lock1->li_file, lock1->li_line); printf(" 2nd %p %s (%s) @ %s:%d\n", lock, lock->lo_name, w->w_name, file, line); } else { printf(" 1st %p %s (%s) @ %s:%d\n", lock2->li_lock, lock2->li_lock->lo_name, lock2->li_lock->lo_witness->w_name, lock2->li_file, lock2->li_line); printf(" 2nd %p %s (%s) @ %s:%d\n", lock1->li_lock, lock1->li_lock->lo_name, w1->w_name, lock1->li_file, lock1->li_line); printf(" 3rd %p %s (%s) @ %s:%d\n", lock, lock->lo_name, w->w_name, file, line); } witness_debugger(1); return; } } /* * If requested, build a new lock order. However, don't build a new * relationship between a sleepable lock and Giant if it is in the * wrong direction. The correct lock order is that sleepable locks * always come before Giant. */ if (flags & LOP_NEWORDER && !(plock->li_lock == &Giant.lock_object && (lock->lo_flags & LO_SLEEPABLE) != 0)) { CTR3(KTR_WITNESS, "%s: adding %s as a child of %s", __func__, w->w_name, plock->li_lock->lo_witness->w_name); itismychild(plock->li_lock->lo_witness, w); } out: mtx_unlock_spin(&w_mtx); } void witness_lock(struct lock_object *lock, int flags, const char *file, int line) { struct lock_list_entry **lock_list, *lle; struct lock_instance *instance; struct witness *w; struct thread *td; if (witness_cold || witness_watch == -1 || lock->lo_witness == NULL || panicstr != NULL) return; w = lock->lo_witness; td = curthread; file = fixup_filename(file); /* Determine lock list for this lock. */ if (LOCK_CLASS(lock)->lc_flags & LC_SLEEPLOCK) lock_list = &td->td_sleeplocks; else lock_list = PCPU_PTR(spinlocks); /* Check to see if we are recursing on a lock we already own. */ instance = find_instance(*lock_list, lock); if (instance != NULL) { instance->li_flags++; CTR4(KTR_WITNESS, "%s: pid %d recursed on %s r=%d", __func__, td->td_proc->p_pid, lock->lo_name, instance->li_flags & LI_RECURSEMASK); instance->li_file = file; instance->li_line = line; return; } /* Update per-witness last file and line acquire. */ w->w_file = file; w->w_line = line; /* Find the next open lock instance in the list and fill it. */ lle = *lock_list; if (lle == NULL || lle->ll_count == LOCK_NCHILDREN) { lle = witness_lock_list_get(); if (lle == NULL) return; lle->ll_next = *lock_list; CTR3(KTR_WITNESS, "%s: pid %d added lle %p", __func__, td->td_proc->p_pid, lle); *lock_list = lle; } instance = &lle->ll_children[lle->ll_count++]; instance->li_lock = lock; instance->li_line = line; instance->li_file = file; if ((flags & LOP_EXCLUSIVE) != 0) instance->li_flags = LI_EXCLUSIVE; else instance->li_flags = 0; CTR4(KTR_WITNESS, "%s: pid %d added %s as lle[%d]", __func__, td->td_proc->p_pid, lock->lo_name, lle->ll_count - 1); } void witness_upgrade(struct lock_object *lock, int flags, const char *file, int line) { struct lock_instance *instance; struct lock_class *class; KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) return; class = LOCK_CLASS(lock); file = fixup_filename(file); if (witness_watch) { if ((lock->lo_flags & LO_UPGRADABLE) == 0) panic("upgrade of non-upgradable lock (%s) %s @ %s:%d", class->lc_name, lock->lo_name, file, line); if ((class->lc_flags & LC_SLEEPLOCK) == 0) panic("upgrade of non-sleep lock (%s) %s @ %s:%d", class->lc_name, lock->lo_name, file, line); } instance = find_instance(curthread->td_sleeplocks, lock); if (instance == NULL) panic("upgrade of unlocked lock (%s) %s @ %s:%d", class->lc_name, lock->lo_name, file, line); if (witness_watch) { if ((instance->li_flags & LI_EXCLUSIVE) != 0) panic("upgrade of exclusive lock (%s) %s @ %s:%d", class->lc_name, lock->lo_name, file, line); if ((instance->li_flags & LI_RECURSEMASK) != 0) panic("upgrade of recursed lock (%s) %s r=%d @ %s:%d", class->lc_name, lock->lo_name, instance->li_flags & LI_RECURSEMASK, file, line); } instance->li_flags |= LI_EXCLUSIVE; } void witness_downgrade(struct lock_object *lock, int flags, const char *file, int line) { struct lock_instance *instance; struct lock_class *class; KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) return; class = LOCK_CLASS(lock); file = fixup_filename(file); if (witness_watch) { if ((lock->lo_flags & LO_UPGRADABLE) == 0) panic("downgrade of non-upgradable lock (%s) %s @ %s:%d", class->lc_name, lock->lo_name, file, line); if ((class->lc_flags & LC_SLEEPLOCK) == 0) panic("downgrade of non-sleep lock (%s) %s @ %s:%d", class->lc_name, lock->lo_name, file, line); } instance = find_instance(curthread->td_sleeplocks, lock); if (instance == NULL) panic("downgrade of unlocked lock (%s) %s @ %s:%d", class->lc_name, lock->lo_name, file, line); if (witness_watch) { if ((instance->li_flags & LI_EXCLUSIVE) == 0) panic("downgrade of shared lock (%s) %s @ %s:%d", class->lc_name, lock->lo_name, file, line); if ((instance->li_flags & LI_RECURSEMASK) != 0) panic("downgrade of recursed lock (%s) %s r=%d @ %s:%d", class->lc_name, lock->lo_name, instance->li_flags & LI_RECURSEMASK, file, line); } instance->li_flags &= ~LI_EXCLUSIVE; } void witness_unlock(struct lock_object *lock, int flags, const char *file, int line) { struct lock_list_entry **lock_list, *lle; struct lock_instance *instance; struct lock_class *class; struct thread *td; register_t s; int i, j; if (witness_cold || lock->lo_witness == NULL || panicstr != NULL) return; td = curthread; class = LOCK_CLASS(lock); file = fixup_filename(file); /* Find lock instance associated with this lock. */ if (class->lc_flags & LC_SLEEPLOCK) lock_list = &td->td_sleeplocks; else lock_list = PCPU_PTR(spinlocks); lle = *lock_list; for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) for (i = 0; i < (*lock_list)->ll_count; i++) { instance = &(*lock_list)->ll_children[i]; if (instance->li_lock == lock) goto found; } /* * When disabling WITNESS through witness_watch we could end up in * having registered locks in the td_sleeplocks queue. * We have to make sure we flush these queues, so just search for * eventual register locks and remove them. */ if (witness_watch > 0) panic("lock (%s) %s not locked @ %s:%d", class->lc_name, lock->lo_name, file, line); else return; found: /* First, check for shared/exclusive mismatches. */ if ((instance->li_flags & LI_EXCLUSIVE) != 0 && witness_watch > 0 && (flags & LOP_EXCLUSIVE) == 0) { printf("shared unlock of (%s) %s @ %s:%d\n", class->lc_name, lock->lo_name, file, line); printf("while exclusively locked from %s:%d\n", instance->li_file, instance->li_line); panic("excl->ushare"); } if ((instance->li_flags & LI_EXCLUSIVE) == 0 && witness_watch > 0 && (flags & LOP_EXCLUSIVE) != 0) { printf("exclusive unlock of (%s) %s @ %s:%d\n", class->lc_name, lock->lo_name, file, line); printf("while share locked from %s:%d\n", instance->li_file, instance->li_line); panic("share->uexcl"); } /* If we are recursed, unrecurse. */ if ((instance->li_flags & LI_RECURSEMASK) > 0) { CTR4(KTR_WITNESS, "%s: pid %d unrecursed on %s r=%d", __func__, td->td_proc->p_pid, instance->li_lock->lo_name, instance->li_flags); instance->li_flags--; return; } /* Otherwise, remove this item from the list. */ s = intr_disable(); CTR4(KTR_WITNESS, "%s: pid %d removed %s from lle[%d]", __func__, td->td_proc->p_pid, instance->li_lock->lo_name, (*lock_list)->ll_count - 1); for (j = i; j < (*lock_list)->ll_count - 1; j++) (*lock_list)->ll_children[j] = (*lock_list)->ll_children[j + 1]; (*lock_list)->ll_count--; intr_restore(s); /* * In order to reduce contention on w_mtx, we want to keep always an * head object into lists so that frequent allocation from the * free witness pool (and subsequent locking) is avoided. * In order to maintain the current code simple, when the head * object is totally unloaded it means also that we do not have * further objects in the list, so the list ownership needs to be * hand over to another object if the current head needs to be freed. */ if ((*lock_list)->ll_count == 0) { if (*lock_list == lle) { if (lle->ll_next == NULL) return; } else lle = *lock_list; *lock_list = lle->ll_next; CTR3(KTR_WITNESS, "%s: pid %d removed lle %p", __func__, td->td_proc->p_pid, lle); witness_lock_list_free(lle); } } void witness_thread_exit(struct thread *td) { struct lock_list_entry *lle; int i, n; lle = td->td_sleeplocks; if (lle == NULL || panicstr != NULL) return; if (lle->ll_count != 0) { for (n = 0; lle != NULL; lle = lle->ll_next) for (i = lle->ll_count - 1; i >= 0; i--) { if (n == 0) printf("Thread %p exiting with the following locks held:\n", td); n++; witness_list_lock(&lle->ll_children[i]); } panic("Thread %p cannot exit while holding sleeplocks\n", td); } witness_lock_list_free(lle); } /* * Warn if any locks other than 'lock' are held. Flags can be passed in to * exempt Giant and sleepable locks from the checks as well. If any * non-exempt locks are held, then a supplied message is printed to the * console along with a list of the offending locks. If indicated in the * flags then a failure results in a panic as well. */ int witness_warn(int flags, struct lock_object *lock, const char *fmt, ...) { struct lock_list_entry *lock_list, *lle; struct lock_instance *lock1; struct thread *td; va_list ap; int i, n; if (witness_cold || witness_watch < 1 || panicstr != NULL) return (0); n = 0; td = curthread; for (lle = td->td_sleeplocks; lle != NULL; lle = lle->ll_next) for (i = lle->ll_count - 1; i >= 0; i--) { lock1 = &lle->ll_children[i]; if (lock1->li_lock == lock) continue; if (flags & WARN_GIANTOK && lock1->li_lock == &Giant.lock_object) continue; if (flags & WARN_SLEEPOK && (lock1->li_lock->lo_flags & LO_SLEEPABLE) != 0) continue; if (n == 0) { va_start(ap, fmt); vprintf(fmt, ap); va_end(ap); printf(" with the following"); if (flags & WARN_SLEEPOK) printf(" non-sleepable"); printf(" locks held:\n"); } n++; witness_list_lock(lock1); } /* * Pin the thread in order to avoid problems with thread migration. * Once that all verifies are passed about spinlocks ownership, * the thread is in a safe path and it can be unpinned. */ sched_pin(); lock_list = PCPU_GET(spinlocks); if (lock_list != NULL && lock_list->ll_count != 0) { sched_unpin(); /* * We should only have one spinlock and as long as * the flags cannot match for this locks class, * check if the first spinlock is the one curthread * should hold. */ lock1 = &lock_list->ll_children[lock_list->ll_count - 1]; if (lock_list->ll_count == 1 && lock_list->ll_next == NULL && lock1->li_lock == lock && n == 0) return (0); va_start(ap, fmt); vprintf(fmt, ap); va_end(ap); printf(" with the following"); if (flags & WARN_SLEEPOK) printf(" non-sleepable"); printf(" locks held:\n"); n += witness_list_locks(&lock_list); } else sched_unpin(); if (flags & WARN_PANIC && n) panic("%s", __func__); else witness_debugger(n); return (n); } const char * witness_file(struct lock_object *lock) { struct witness *w; if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) return ("?"); w = lock->lo_witness; return (w->w_file); } int witness_line(struct lock_object *lock) { struct witness *w; if (witness_cold || witness_watch < 1 || lock->lo_witness == NULL) return (0); w = lock->lo_witness; return (w->w_line); } static struct witness * enroll(const char *description, struct lock_class *lock_class) { struct witness *w; struct witness_list *typelist; MPASS(description != NULL); if (witness_watch == -1 || panicstr != NULL) return (NULL); if ((lock_class->lc_flags & LC_SPINLOCK)) { if (witness_skipspin) return (NULL); else typelist = &w_spin; } else if ((lock_class->lc_flags & LC_SLEEPLOCK)) typelist = &w_sleep; else panic("lock class %s is not sleep or spin", lock_class->lc_name); mtx_lock_spin(&w_mtx); w = witness_hash_get(description); if (w) goto found; if ((w = witness_get()) == NULL) return (NULL); MPASS(strlen(description) < MAX_W_NAME); strcpy(w->w_name, description); w->w_class = lock_class; w->w_refcount = 1; STAILQ_INSERT_HEAD(&w_all, w, w_list); if (lock_class->lc_flags & LC_SPINLOCK) { STAILQ_INSERT_HEAD(&w_spin, w, w_typelist); w_spin_cnt++; } else if (lock_class->lc_flags & LC_SLEEPLOCK) { STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); w_sleep_cnt++; } /* Insert new witness into the hash */ witness_hash_put(w); witness_increment_graph_generation(); mtx_unlock_spin(&w_mtx); return (w); found: w->w_refcount++; mtx_unlock_spin(&w_mtx); if (lock_class != w->w_class) panic( "lock (%s) %s does not match earlier (%s) lock", description, lock_class->lc_name, w->w_class->lc_name); return (w); } static void depart(struct witness *w) { struct witness_list *list; MPASS(w->w_refcount == 0); if (w->w_class->lc_flags & LC_SLEEPLOCK) { list = &w_sleep; w_sleep_cnt--; } else { list = &w_spin; w_spin_cnt--; } /* * Set file to NULL as it may point into a loadable module. */ w->w_file = NULL; w->w_line = 0; witness_increment_graph_generation(); } static void adopt(struct witness *parent, struct witness *child) { int pi, ci, i, j; if (witness_cold == 0) mtx_assert(&w_mtx, MA_OWNED); /* If the relationship is already known, there's no work to be done. */ if (isitmychild(parent, child)) return; /* When the structure of the graph changes, bump up the generation. */ witness_increment_graph_generation(); /* * The hard part ... create the direct relationship, then propagate all * indirect relationships. */ pi = parent->w_index; ci = child->w_index; WITNESS_INDEX_ASSERT(pi); WITNESS_INDEX_ASSERT(ci); MPASS(pi != ci); w_rmatrix[pi][ci] |= WITNESS_PARENT; w_rmatrix[ci][pi] |= WITNESS_CHILD; /* * If parent was not already an ancestor of child, * then we increment the descendant and ancestor counters. */ if ((w_rmatrix[pi][ci] & WITNESS_ANCESTOR) == 0) { parent->w_num_descendants++; child->w_num_ancestors++; } /* * Find each ancestor of 'pi'. Note that 'pi' itself is counted as * an ancestor of 'pi' during this loop. */ for (i = 1; i <= w_max_used_index; i++) { if ((w_rmatrix[i][pi] & WITNESS_ANCESTOR_MASK) == 0 && (i != pi)) continue; /* Find each descendant of 'i' and mark it as a descendant. */ for (j = 1; j <= w_max_used_index; j++) { /* * Skip children that are already marked as * descendants of 'i'. */ if (w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) continue; /* * We are only interested in descendants of 'ci'. Note * that 'ci' itself is counted as a descendant of 'ci'. */ if ((w_rmatrix[ci][j] & WITNESS_ANCESTOR_MASK) == 0 && (j != ci)) continue; w_rmatrix[i][j] |= WITNESS_ANCESTOR; w_rmatrix[j][i] |= WITNESS_DESCENDANT; w_data[i].w_num_descendants++; w_data[j].w_num_ancestors++; /* * Make sure we aren't marking a node as both an * ancestor and descendant. We should have caught * this as a lock order reversal earlier. */ if ((w_rmatrix[i][j] & WITNESS_ANCESTOR_MASK) && (w_rmatrix[i][j] & WITNESS_DESCENDANT_MASK)) { printf("witness rmatrix paradox! [%d][%d]=%d " "both ancestor and descendant\n", i, j, w_rmatrix[i][j]); kdb_backtrace(); printf("Witness disabled.\n"); witness_watch = -1; } if ((w_rmatrix[j][i] & WITNESS_ANCESTOR_MASK) && (w_rmatrix[j][i] & WITNESS_DESCENDANT_MASK)) { printf("witness rmatrix paradox! [%d][%d]=%d " "both ancestor and descendant\n", j, i, w_rmatrix[j][i]); kdb_backtrace(); printf("Witness disabled.\n"); witness_watch = -1; } } } } static void itismychild(struct witness *parent, struct witness *child) { MPASS(child != NULL && parent != NULL); if (witness_cold == 0) mtx_assert(&w_mtx, MA_OWNED); if (!witness_lock_type_equal(parent, child)) { if (witness_cold == 0) mtx_unlock_spin(&w_mtx); panic("%s: parent \"%s\" (%s) and child \"%s\" (%s) are not " "the same lock type", __func__, parent->w_name, parent->w_class->lc_name, child->w_name, child->w_class->lc_name); } adopt(parent, child); } /* * Generic code for the isitmy*() functions. The rmask parameter is the * expected relationship of w1 to w2. */ static int _isitmyx(struct witness *w1, struct witness *w2, int rmask, const char *fname) { unsigned char r1, r2; int i1, i2; i1 = w1->w_index; i2 = w2->w_index; WITNESS_INDEX_ASSERT(i1); WITNESS_INDEX_ASSERT(i2); r1 = w_rmatrix[i1][i2] & WITNESS_RELATED_MASK; r2 = w_rmatrix[i2][i1] & WITNESS_RELATED_MASK; /* The flags on one better be the inverse of the flags on the other */ if (!((WITNESS_ATOD(r1) == r2 && WITNESS_DTOA(r2) == r1) || (WITNESS_DTOA(r1) == r2 && WITNESS_ATOD(r2) == r1))) { printf("%s: rmatrix mismatch between %s (index %d) and %s " "(index %d): w_rmatrix[%d][%d] == %hhx but " "w_rmatrix[%d][%d] == %hhx\n", fname, w1->w_name, i1, w2->w_name, i2, i1, i2, r1, i2, i1, r2); kdb_backtrace(); printf("Witness disabled.\n"); witness_watch = -1; } return (r1 & rmask); } /* * Checks if @child is a direct child of @parent. */ static int isitmychild(struct witness *parent, struct witness *child) { return (_isitmyx(parent, child, WITNESS_PARENT, __func__)); } /* * Checks if @descendant is a direct or inderect descendant of @ancestor. */ static int isitmydescendant(struct witness *ancestor, struct witness *descendant) { return (_isitmyx(ancestor, descendant, WITNESS_ANCESTOR_MASK, __func__)); } #ifdef BLESSING static int blessed(struct witness *w1, struct witness *w2) { int i; struct witness_blessed *b; for (i = 0; i < blessed_count; i++) { b = &blessed_list[i]; if (strcmp(w1->w_name, b->b_lock1) == 0) { if (strcmp(w2->w_name, b->b_lock2) == 0) return (1); continue; } if (strcmp(w1->w_name, b->b_lock2) == 0) if (strcmp(w2->w_name, b->b_lock1) == 0) return (1); } return (0); } #endif static struct witness * witness_get(void) { struct witness *w; int index; if (witness_cold == 0) mtx_assert(&w_mtx, MA_OWNED); if (witness_watch == -1) { mtx_unlock_spin(&w_mtx); return (NULL); } if (STAILQ_EMPTY(&w_free)) { witness_watch = -1; mtx_unlock_spin(&w_mtx); printf("WITNESS: unable to allocate a new witness object\n"); return (NULL); } w = STAILQ_FIRST(&w_free); STAILQ_REMOVE_HEAD(&w_free, w_list); w_free_cnt--; index = w->w_index; MPASS(index > 0 && index == w_max_used_index+1 && index < WITNESS_COUNT); bzero(w, sizeof(*w)); w->w_index = index; if (index > w_max_used_index) w_max_used_index = index; return (w); } static void witness_free(struct witness *w) { STAILQ_INSERT_HEAD(&w_free, w, w_list); w_free_cnt++; } static struct lock_list_entry * witness_lock_list_get(void) { struct lock_list_entry *lle; if (witness_watch == -1) return (NULL); mtx_lock_spin(&w_mtx); lle = w_lock_list_free; if (lle == NULL) { witness_watch = -1; mtx_unlock_spin(&w_mtx); printf("%s: witness exhausted\n", __func__); return (NULL); } w_lock_list_free = lle->ll_next; mtx_unlock_spin(&w_mtx); bzero(lle, sizeof(*lle)); return (lle); } static void witness_lock_list_free(struct lock_list_entry *lle) { mtx_lock_spin(&w_mtx); lle->ll_next = w_lock_list_free; w_lock_list_free = lle; mtx_unlock_spin(&w_mtx); } static struct lock_instance * find_instance(struct lock_list_entry *list, struct lock_object *lock) { struct lock_list_entry *lle; struct lock_instance *instance; int i; for (lle = list; lle != NULL; lle = lle->ll_next) for (i = lle->ll_count - 1; i >= 0; i--) { instance = &lle->ll_children[i]; if (instance->li_lock == lock) return (instance); } return (NULL); } static void witness_list_lock(struct lock_instance *instance) { struct lock_object *lock; lock = instance->li_lock; printf("%s %s %s", (instance->li_flags & LI_EXCLUSIVE) != 0 ? "exclusive" : "shared", LOCK_CLASS(lock)->lc_name, lock->lo_name); if (lock->lo_witness->w_name != lock->lo_name) printf(" (%s)", lock->lo_witness->w_name); printf(" r = %d (%p) locked @ %s:%d\n", instance->li_flags & LI_RECURSEMASK, lock, instance->li_file, instance->li_line); } #ifdef DDB static int witness_thread_has_locks(struct thread *td) { if (td->td_sleeplocks == NULL) return (0); return (td->td_sleeplocks->ll_count != 0); } static int witness_proc_has_locks(struct proc *p) { struct thread *td; FOREACH_THREAD_IN_PROC(p, td) { if (witness_thread_has_locks(td)) return (1); } return (0); } #endif int witness_list_locks(struct lock_list_entry **lock_list) { struct lock_list_entry *lle; int i, nheld; nheld = 0; for (lle = *lock_list; lle != NULL; lle = lle->ll_next) for (i = lle->ll_count - 1; i >= 0; i--) { witness_list_lock(&lle->ll_children[i]); nheld++; } return (nheld); } /* * This is a bit risky at best. We call this function when we have timed * out acquiring a spin lock, and we assume that the other CPU is stuck * with this lock held. So, we go groveling around in the other CPU's * per-cpu data to try to find the lock instance for this spin lock to * see when it was last acquired. */ void witness_display_spinlock(struct lock_object *lock, struct thread *owner) { struct lock_instance *instance; struct pcpu *pc; if (owner->td_critnest == 0 || owner->td_oncpu == NOCPU) return; pc = pcpu_find(owner->td_oncpu); instance = find_instance(pc->pc_spinlocks, lock); if (instance != NULL) witness_list_lock(instance); } void witness_save(struct lock_object *lock, const char **filep, int *linep) { struct lock_list_entry *lock_list; struct lock_instance *instance; struct lock_class *class; KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) return; class = LOCK_CLASS(lock); if (class->lc_flags & LC_SLEEPLOCK) lock_list = curthread->td_sleeplocks; else { if (witness_skipspin) return; lock_list = PCPU_GET(spinlocks); } instance = find_instance(lock_list, lock); if (instance == NULL) panic("%s: lock (%s) %s not locked", __func__, class->lc_name, lock->lo_name); *filep = instance->li_file; *linep = instance->li_line; } void witness_restore(struct lock_object *lock, const char *file, int line) { struct lock_list_entry *lock_list; struct lock_instance *instance; struct lock_class *class; KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); if (lock->lo_witness == NULL || witness_watch == -1 || panicstr != NULL) return; class = LOCK_CLASS(lock); if (class->lc_flags & LC_SLEEPLOCK) lock_list = curthread->td_sleeplocks; else { if (witness_skipspin) return; lock_list = PCPU_GET(spinlocks); } instance = find_instance(lock_list, lock); if (instance == NULL) panic("%s: lock (%s) %s not locked", __func__, class->lc_name, lock->lo_name); lock->lo_witness->w_file = file; lock->lo_witness->w_line = line; instance->li_file = file; instance->li_line = line; } void witness_assert(struct lock_object *lock, int flags, const char *file, int line) { #ifdef INVARIANT_SUPPORT struct lock_instance *instance; struct lock_class *class; if (lock->lo_witness == NULL || witness_watch < 1 || panicstr != NULL) return; class = LOCK_CLASS(lock); if ((class->lc_flags & LC_SLEEPLOCK) != 0) instance = find_instance(curthread->td_sleeplocks, lock); else if ((class->lc_flags & LC_SPINLOCK) != 0) instance = find_instance(PCPU_GET(spinlocks), lock); else { panic("Lock (%s) %s is not sleep or spin!", class->lc_name, lock->lo_name); } file = fixup_filename(file); switch (flags) { case LA_UNLOCKED: if (instance != NULL) panic("Lock (%s) %s locked @ %s:%d.", class->lc_name, lock->lo_name, file, line); break; case LA_LOCKED: case LA_LOCKED | LA_RECURSED: case LA_LOCKED | LA_NOTRECURSED: case LA_SLOCKED: case LA_SLOCKED | LA_RECURSED: case LA_SLOCKED | LA_NOTRECURSED: case LA_XLOCKED: case LA_XLOCKED | LA_RECURSED: case LA_XLOCKED | LA_NOTRECURSED: if (instance == NULL) { panic("Lock (%s) %s not locked @ %s:%d.", class->lc_name, lock->lo_name, file, line); break; } if ((flags & LA_XLOCKED) != 0 && (instance->li_flags & LI_EXCLUSIVE) == 0) panic("Lock (%s) %s not exclusively locked @ %s:%d.", class->lc_name, lock->lo_name, file, line); if ((flags & LA_SLOCKED) != 0 && (instance->li_flags & LI_EXCLUSIVE) != 0) panic("Lock (%s) %s exclusively locked @ %s:%d.", class->lc_name, lock->lo_name, file, line); if ((flags & LA_RECURSED) != 0 && (instance->li_flags & LI_RECURSEMASK) == 0) panic("Lock (%s) %s not recursed @ %s:%d.", class->lc_name, lock->lo_name, file, line); if ((flags & LA_NOTRECURSED) != 0 && (instance->li_flags & LI_RECURSEMASK) != 0) panic("Lock (%s) %s recursed @ %s:%d.", class->lc_name, lock->lo_name, file, line); break; default: panic("Invalid lock assertion at %s:%d.", file, line); } #endif /* INVARIANT_SUPPORT */ } #ifdef DDB static void witness_ddb_list(struct thread *td) { KASSERT(witness_cold == 0, ("%s: witness_cold", __func__)); KASSERT(kdb_active, ("%s: not in the debugger", __func__)); if (witness_watch < 1) return; witness_list_locks(&td->td_sleeplocks); /* * We only handle spinlocks if td == curthread. This is somewhat broken * if td is currently executing on some other CPU and holds spin locks * as we won't display those locks. If we had a MI way of getting * the per-cpu data for a given cpu then we could use * td->td_oncpu to get the list of spinlocks for this thread * and "fix" this. * * That still wouldn't really fix this unless we locked the scheduler * lock or stopped the other CPU to make sure it wasn't changing the * list out from under us. It is probably best to just not try to * handle threads on other CPU's for now. */ if (td == curthread && PCPU_GET(spinlocks) != NULL) witness_list_locks(PCPU_PTR(spinlocks)); } DB_SHOW_COMMAND(locks, db_witness_list) { struct thread *td; if (have_addr) td = db_lookup_thread(addr, TRUE); else td = kdb_thread; witness_ddb_list(td); } DB_SHOW_ALL_COMMAND(locks, db_witness_list_all) { struct thread *td; struct proc *p; /* * It would be nice to list only threads and processes that actually * held sleep locks, but that information is currently not exported * by WITNESS. */ FOREACH_PROC_IN_SYSTEM(p) { if (!witness_proc_has_locks(p)) continue; FOREACH_THREAD_IN_PROC(p, td) { if (!witness_thread_has_locks(td)) continue; db_printf("Process %d (%s) thread %p (%d)\n", p->p_pid, p->p_comm, td, td->td_tid); witness_ddb_list(td); } } } DB_SHOW_ALIAS(alllocks, db_witness_list_all) DB_SHOW_COMMAND(witness, db_witness_display) { witness_ddb_display(db_printf); } #endif static int sysctl_debug_witness_badstacks(SYSCTL_HANDLER_ARGS) { struct witness_lock_order_data *data1, *data2, *tmp_data1, *tmp_data2; struct witness *tmp_w1, *tmp_w2, *w1, *w2; struct sbuf *sb; u_int w_rmatrix1, w_rmatrix2; int error, generation, i, j; tmp_data1 = NULL; tmp_data2 = NULL; tmp_w1 = NULL; tmp_w2 = NULL; if (witness_watch < 1) { error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); return (error); } if (witness_cold) { error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); return (error); } error = 0; sb = sbuf_new(NULL, NULL, BADSTACK_SBUF_SIZE, SBUF_AUTOEXTEND); if (sb == NULL) return (ENOMEM); /* Allocate and init temporary storage space. */ tmp_w1 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); tmp_w2 = malloc(sizeof(struct witness), M_TEMP, M_WAITOK | M_ZERO); tmp_data1 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, M_WAITOK | M_ZERO); tmp_data2 = malloc(sizeof(struct witness_lock_order_data), M_TEMP, M_WAITOK | M_ZERO); stack_zero(&tmp_data1->wlod_stack); stack_zero(&tmp_data2->wlod_stack); restart: mtx_lock_spin(&w_mtx); generation = w_generation; mtx_unlock_spin(&w_mtx); sbuf_printf(sb, "Number of known direct relationships is %d\n", w_lohash.wloh_count); for (i = 1; i < w_max_used_index; i++) { mtx_lock_spin(&w_mtx); if (generation != w_generation) { mtx_unlock_spin(&w_mtx); /* The graph has changed, try again. */ req->oldidx = 0; sbuf_clear(sb); goto restart; } w1 = &w_data[i]; if (w1->w_reversed == 0) { mtx_unlock_spin(&w_mtx); continue; } /* Copy w1 locally so we can release the spin lock. */ *tmp_w1 = *w1; mtx_unlock_spin(&w_mtx); if (tmp_w1->w_reversed == 0) continue; for (j = 1; j < w_max_used_index; j++) { if ((w_rmatrix[i][j] & WITNESS_REVERSAL) == 0 || i > j) continue; mtx_lock_spin(&w_mtx); if (generation != w_generation) { mtx_unlock_spin(&w_mtx); /* The graph has changed, try again. */ req->oldidx = 0; sbuf_clear(sb); goto restart; } w2 = &w_data[j]; data1 = witness_lock_order_get(w1, w2); data2 = witness_lock_order_get(w2, w1); /* * Copy information locally so we can release the * spin lock. */ *tmp_w2 = *w2; w_rmatrix1 = (unsigned int)w_rmatrix[i][j]; w_rmatrix2 = (unsigned int)w_rmatrix[j][i]; if (data1) { stack_zero(&tmp_data1->wlod_stack); stack_copy(&data1->wlod_stack, &tmp_data1->wlod_stack); } if (data2 && data2 != data1) { stack_zero(&tmp_data2->wlod_stack); stack_copy(&data2->wlod_stack, &tmp_data2->wlod_stack); } mtx_unlock_spin(&w_mtx); sbuf_printf(sb, "\nLock order reversal between \"%s\"(%s) and \"%s\"(%s)!\n", tmp_w1->w_name, tmp_w1->w_class->lc_name, tmp_w2->w_name, tmp_w2->w_class->lc_name); #if 0 sbuf_printf(sb, "w_rmatrix[%s][%s] == %x, w_rmatrix[%s][%s] == %x\n", tmp_w1->name, tmp_w2->w_name, w_rmatrix1, tmp_w2->name, tmp_w1->w_name, w_rmatrix2); #endif if (data1) { sbuf_printf(sb, "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", tmp_w1->w_name, tmp_w1->w_class->lc_name, tmp_w2->w_name, tmp_w2->w_class->lc_name); stack_sbuf_print(sb, &tmp_data1->wlod_stack); sbuf_printf(sb, "\n"); } if (data2 && data2 != data1) { sbuf_printf(sb, "Lock order \"%s\"(%s) -> \"%s\"(%s) first seen at:\n", tmp_w2->w_name, tmp_w2->w_class->lc_name, tmp_w1->w_name, tmp_w1->w_class->lc_name); stack_sbuf_print(sb, &tmp_data2->wlod_stack); sbuf_printf(sb, "\n"); } } } mtx_lock_spin(&w_mtx); if (generation != w_generation) { mtx_unlock_spin(&w_mtx); /* * The graph changed while we were printing stack data, * try again. */ req->oldidx = 0; sbuf_clear(sb); goto restart; } mtx_unlock_spin(&w_mtx); /* Free temporary storage space. */ free(tmp_data1, M_TEMP); free(tmp_data2, M_TEMP); free(tmp_w1, M_TEMP); free(tmp_w2, M_TEMP); sbuf_finish(sb); error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); sbuf_delete(sb); return (error); } static int sysctl_debug_witness_fullgraph(SYSCTL_HANDLER_ARGS) { struct witness *w; struct sbuf *sb; int error; if (witness_watch < 1) { error = SYSCTL_OUT(req, w_notrunning, sizeof(w_notrunning)); return (error); } if (witness_cold) { error = SYSCTL_OUT(req, w_stillcold, sizeof(w_stillcold)); return (error); } error = 0; sb = sbuf_new(NULL, NULL, FULLGRAPH_SBUF_SIZE, SBUF_FIXEDLEN); if (sb == NULL) return (ENOMEM); sbuf_printf(sb, "\n"); mtx_lock_spin(&w_mtx); STAILQ_FOREACH(w, &w_all, w_list) w->w_displayed = 0; STAILQ_FOREACH(w, &w_all, w_list) witness_add_fullgraph(sb, w); mtx_unlock_spin(&w_mtx); /* * While using SBUF_FIXEDLEN, check if the sbuf overflowed. */ if (sbuf_overflowed(sb)) { sbuf_delete(sb); panic("%s: sbuf overflowed, bump FULLGRAPH_SBUF_SIZE value\n", __func__); } /* * Close the sbuf and return to userland. */ sbuf_finish(sb); error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); sbuf_delete(sb); return (error); } static int sysctl_debug_witness_watch(SYSCTL_HANDLER_ARGS) { int error, value; value = witness_watch; error = sysctl_handle_int(oidp, &value, 0, req); if (error != 0 || req->newptr == NULL) return (error); if (value > 1 || value < -1 || (witness_watch == -1 && value != witness_watch)) return (EINVAL); witness_watch = value; return (0); } static void witness_add_fullgraph(struct sbuf *sb, struct witness *w) { int i; if (w->w_displayed != 0 || (w->w_file == NULL && w->w_line == 0)) return; w->w_displayed = 1; WITNESS_INDEX_ASSERT(w->w_index); for (i = 1; i <= w_max_used_index; i++) { if (w_rmatrix[w->w_index][i] & WITNESS_PARENT) { sbuf_printf(sb, "\"%s\",\"%s\"\n", w->w_name, w_data[i].w_name); witness_add_fullgraph(sb, &w_data[i]); } } } /* * A simple hash function. Takes a key pointer and a key size. If size == 0, * interprets the key as a string and reads until the null * terminator. Otherwise, reads the first size bytes. Returns an unsigned 32-bit * hash value computed from the key. */ static uint32_t witness_hash_djb2(const uint8_t *key, uint32_t size) { unsigned int hash = 5381; int i; /* hash = hash * 33 + key[i] */ if (size) for (i = 0; i < size; i++) hash = ((hash << 5) + hash) + (unsigned int)key[i]; else for (i = 0; key[i] != 0; i++) hash = ((hash << 5) + hash) + (unsigned int)key[i]; return (hash); } /* * Initializes the two witness hash tables. Called exactly once from * witness_initialize(). */ static void witness_init_hash_tables(void) { int i; MPASS(witness_cold); /* Initialize the hash tables. */ for (i = 0; i < WITNESS_HASH_SIZE; i++) w_hash.wh_array[i] = NULL; w_hash.wh_size = WITNESS_HASH_SIZE; w_hash.wh_count = 0; /* Initialize the lock order data hash. */ w_lofree = NULL; for (i = 0; i < WITNESS_LO_DATA_COUNT; i++) { memset(&w_lodata[i], 0, sizeof(w_lodata[i])); w_lodata[i].wlod_next = w_lofree; w_lofree = &w_lodata[i]; } w_lohash.wloh_size = WITNESS_LO_HASH_SIZE; w_lohash.wloh_count = 0; for (i = 0; i < WITNESS_LO_HASH_SIZE; i++) w_lohash.wloh_array[i] = NULL; } static struct witness * witness_hash_get(const char *key) { struct witness *w; uint32_t hash; MPASS(key != NULL); if (witness_cold == 0) mtx_assert(&w_mtx, MA_OWNED); hash = witness_hash_djb2(key, 0) % w_hash.wh_size; w = w_hash.wh_array[hash]; while (w != NULL) { if (strcmp(w->w_name, key) == 0) goto out; w = w->w_hash_next; } out: return (w); } static void witness_hash_put(struct witness *w) { uint32_t hash; MPASS(w != NULL); MPASS(w->w_name != NULL); if (witness_cold == 0) mtx_assert(&w_mtx, MA_OWNED); KASSERT(witness_hash_get(w->w_name) == NULL, ("%s: trying to add a hash entry that already exists!", __func__)); KASSERT(w->w_hash_next == NULL, ("%s: w->w_hash_next != NULL", __func__)); hash = witness_hash_djb2(w->w_name, 0) % w_hash.wh_size; w->w_hash_next = w_hash.wh_array[hash]; w_hash.wh_array[hash] = w; w_hash.wh_count++; } static struct witness_lock_order_data * witness_lock_order_get(struct witness *parent, struct witness *child) { struct witness_lock_order_data *data = NULL; struct witness_lock_order_key key; unsigned int hash; MPASS(parent != NULL && child != NULL); key.from = parent->w_index; key.to = child->w_index; WITNESS_INDEX_ASSERT(key.from); WITNESS_INDEX_ASSERT(key.to); if ((w_rmatrix[parent->w_index][child->w_index] & WITNESS_LOCK_ORDER_KNOWN) == 0) goto out; hash = witness_hash_djb2((const char*)&key, sizeof(key)) % w_lohash.wloh_size; data = w_lohash.wloh_array[hash]; while (data != NULL) { if (witness_lock_order_key_equal(&data->wlod_key, &key)) break; data = data->wlod_next; } out: return (data); } /* * Verify that parent and child have a known relationship, are not the same, * and child is actually a child of parent. This is done without w_mtx * to avoid contention in the common case. */ static int witness_lock_order_check(struct witness *parent, struct witness *child) { if (parent != child && w_rmatrix[parent->w_index][child->w_index] & WITNESS_LOCK_ORDER_KNOWN && isitmychild(parent, child)) return (1); return (0); } static int witness_lock_order_add(struct witness *parent, struct witness *child) { struct witness_lock_order_data *data = NULL; struct witness_lock_order_key key; unsigned int hash; MPASS(parent != NULL && child != NULL); key.from = parent->w_index; key.to = child->w_index; WITNESS_INDEX_ASSERT(key.from); WITNESS_INDEX_ASSERT(key.to); if (w_rmatrix[parent->w_index][child->w_index] & WITNESS_LOCK_ORDER_KNOWN) return (1); hash = witness_hash_djb2((const char*)&key, sizeof(key)) % w_lohash.wloh_size; w_rmatrix[parent->w_index][child->w_index] |= WITNESS_LOCK_ORDER_KNOWN; data = w_lofree; if (data == NULL) return (0); w_lofree = data->wlod_next; data->wlod_next = w_lohash.wloh_array[hash]; data->wlod_key = key; w_lohash.wloh_array[hash] = data; w_lohash.wloh_count++; stack_zero(&data->wlod_stack); stack_save(&data->wlod_stack); return (1); } /* Call this whenver the structure of the witness graph changes. */ static void witness_increment_graph_generation(void) { if (witness_cold == 0) mtx_assert(&w_mtx, MA_OWNED); w_generation++; } #ifdef KDB static void _witness_debugger(int cond, const char *msg) { if (witness_trace && cond) kdb_backtrace(); if (witness_kdb && cond) kdb_enter(KDB_WHY_WITNESS, msg); } #endif