/*- * 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 $ * $FreeBSD$ */ /* * 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 */ #include "opt_ddb.h" #include "opt_witness.h" #include #include #include #include #include #include #include #include #include #include #include #define WITNESS_COUNT 200 #define WITNESS_CHILDCOUNT (WITNESS_COUNT * 4) /* * XXX: This is somewhat bogus, as we assume here that at most 1024 processes * will hold LOCK_NCHILDREN * 2 locks. We handle failure ok, and we should * probably be safe for the most part, but it's still a SWAG. */ #define LOCK_CHILDCOUNT (MAXCPU + 1024) * 2 #define WITNESS_NCHILDREN 6 struct witness_child_list_entry; struct witness { const char *w_name; 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_child_list_entry *w_children; /* Great evilness... */ const char *w_file; int w_line; u_int w_level; u_int w_refcount; u_char w_Giant_squawked:1; u_char w_other_squawked:1; u_char w_same_squawked:1; }; struct witness_child_list_entry { struct witness_child_list_entry *wcl_next; struct witness *wcl_children[WITNESS_NCHILDREN]; u_int wcl_count; }; STAILQ_HEAD(witness_list, witness); struct witness_blessed { const char *b_lock1; const char *b_lock2; }; struct witness_order_list_entry { const char *w_name; struct lock_class *w_class; }; static struct witness *enroll(const char *description, struct lock_class *lock_class); static int itismychild(struct witness *parent, struct witness *child); static void removechild(struct witness *parent, struct witness *child); static int isitmychild(struct witness *parent, struct witness *child); static int isitmydescendant(struct witness *parent, struct witness *child); static int dup_ok(struct witness *); static int blessed(struct witness *, struct witness *); static void witness_display_list(void(*prnt)(const char *fmt, ...), struct witness_list *list); static void witness_displaydescendants(void(*)(const char *fmt, ...), struct witness *); static void witness_leveldescendents(struct witness *parent, int level); static void witness_levelall(void); static struct witness *witness_get(void); static void witness_free(struct witness *m); static struct witness_child_list_entry *witness_child_get(void); static void witness_child_free(struct witness_child_list_entry *wcl); static struct lock_list_entry *witness_lock_list_get(void); static void witness_lock_list_free(struct lock_list_entry *lle); static void witness_display(void(*)(const char *fmt, ...)); MALLOC_DEFINE(M_WITNESS, "witness", "witness structure"); static int witness_watch; TUNABLE_INT_DECL("debug.witness_watch", 1, witness_watch); SYSCTL_INT(_debug, OID_AUTO, witness_watch, CTLFLAG_RD, &witness_watch, 0, ""); #ifdef DDB /* * When DDB is enabled and witness_ddb is set to 1, it will cause the system to * drop into kdebug() when: * - a lock heirarchy violation occurs * - locks are held when going to sleep. */ int witness_ddb; #ifdef WITNESS_DDB TUNABLE_INT_DECL("debug.witness_ddb", 1, witness_ddb); #else TUNABLE_INT_DECL("debug.witness_ddb", 0, witness_ddb); #endif SYSCTL_INT(_debug, OID_AUTO, witness_ddb, CTLFLAG_RW, &witness_ddb, 0, ""); #endif /* DDB */ int witness_skipspin; #ifdef WITNESS_SKIPSPIN TUNABLE_INT_DECL("debug.witness_skipspin", 1, witness_skipspin); #else TUNABLE_INT_DECL("debug.witness_skipspin", 0, witness_skipspin); #endif SYSCTL_INT(_debug, OID_AUTO, witness_skipspin, CTLFLAG_RD, &witness_skipspin, 0, ""); static struct mtx w_mtx; static struct witness_list w_free = STAILQ_HEAD_INITIALIZER(w_free); static struct witness_list w_all = STAILQ_HEAD_INITIALIZER(w_all); static struct witness_list w_spin = STAILQ_HEAD_INITIALIZER(w_spin); static struct witness_list w_sleep = STAILQ_HEAD_INITIALIZER(w_sleep); static struct witness_child_list_entry *w_child_free = NULL; static struct lock_list_entry *w_lock_list_free = NULL; static int witness_dead; /* fatal error, probably no memory */ static struct witness w_data[WITNESS_COUNT]; static struct witness_child_list_entry w_childdata[WITNESS_CHILDCOUNT]; static struct lock_list_entry w_locklistdata[LOCK_CHILDCOUNT]; static struct witness_order_list_entry order_lists[] = { { "Giant", &lock_class_mtx_sleep }, { "proctree", &lock_class_sx }, { "allproc", &lock_class_sx }, { "process lock", &lock_class_mtx_sleep }, { "uidinfo hash", &lock_class_mtx_sleep }, { "uidinfo struct", &lock_class_mtx_sleep }, { NULL, NULL }, /* * spin locks */ #if defined(__i386__) && defined (SMP) { "com", &lock_class_mtx_spin }, #endif { "sio", &lock_class_mtx_spin }, #ifdef __i386__ { "cy", &lock_class_mtx_spin }, #endif { "ng_node", &lock_class_mtx_spin }, { "ng_worklist", &lock_class_mtx_spin }, { "ithread table lock", &lock_class_mtx_spin }, { "ithread list lock", &lock_class_mtx_spin }, { "sched lock", &lock_class_mtx_spin }, #ifdef __i386__ { "clk", &lock_class_mtx_spin }, #endif { "callout", &lock_class_mtx_spin }, /* * leaf locks */ #ifdef SMP { "ap boot", &lock_class_mtx_spin }, #ifdef __i386__ { "imen", &lock_class_mtx_spin }, #endif { "smp rendezvous", &lock_class_mtx_spin }, #endif { NULL, NULL }, { NULL, NULL } }; static const char *dup_list[] = { "process lock", NULL }; /* * 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); /* * List of all locks in the system. */ STAILQ_HEAD(, lock_object) all_locks = STAILQ_HEAD_INITIALIZER(all_locks); static struct mtx all_mtx = { { &lock_class_mtx_sleep, /* mtx_object.lo_class */ "All locks list", /* mtx_object.lo_name */ NULL, /* mtx_object.lo_file */ 0, /* mtx_object.lo_line */ LO_INITIALIZED, /* mtx_object.lo_flags */ { NULL }, /* mtx_object.lo_list */ NULL }, /* mtx_object.lo_witness */ MTX_UNOWNED, 0, /* mtx_lock, mtx_recurse */ 0, /* mtx_savecrit */ TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), { NULL, NULL } /* mtx_contested */ }; /* * This global is set to 0 once it becomes safe to use the witness code. */ static int witness_cold = 1; /* * Global variables for book keeping. */ static int lock_cur_cnt; static int lock_max_cnt; /* * The WITNESS-enabled diagnostic code. */ static void witness_initialize(void *dummy __unused) { struct lock_object *lock; struct witness_order_list_entry *order; struct witness *w, *w1; int i; /* * 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); STAILQ_INSERT_HEAD(&all_locks, &all_mtx.mtx_object, lo_list); mtx_init(&w_mtx, "witness lock", MTX_SPIN | MTX_QUIET | MTX_NOWITNESS); for (i = 0; i < WITNESS_COUNT; i++) witness_free(&w_data[i]); for (i = 0; i < WITNESS_CHILDCOUNT; i++) witness_child_free(&w_childdata[i]); for (i = 0; i < LOCK_CHILDCOUNT; i++) witness_lock_list_free(&w_locklistdata[i]); /* 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; } } /* Iterate through all locks and add them to witness. */ mtx_lock(&all_mtx); STAILQ_FOREACH(lock, &all_locks, lo_list) { if (lock->lo_flags & LO_WITNESS) lock->lo_witness = enroll(lock->lo_name, lock->lo_class); else lock->lo_witness = NULL; } mtx_unlock(&all_mtx); /* Mark the witness code as being ready for use. */ atomic_store_rel_int(&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) { struct lock_class *class; class = lock->lo_class; if (lock->lo_flags & LO_INITIALIZED) panic("%s: lock (%s) %s is already initialized!\n", __func__, class->lc_name, lock->lo_name); if ((lock->lo_flags & LO_RECURSABLE) != 0 && (class->lc_flags & LC_RECURSABLE) == 0) panic("%s: lock (%s) %s can not be recursable!\n", __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!\n", __func__, class->lc_name, lock->lo_name); mtx_lock(&all_mtx); STAILQ_INSERT_TAIL(&all_locks, lock, lo_list); lock->lo_flags |= LO_INITIALIZED; lock_cur_cnt++; if (lock_cur_cnt > lock_max_cnt) lock_max_cnt = lock_cur_cnt; mtx_unlock(&all_mtx); if (!witness_cold && !witness_dead && (lock->lo_flags & LO_WITNESS) != 0) lock->lo_witness = enroll(lock->lo_name, class); else lock->lo_witness = NULL; } void witness_destroy(struct lock_object *lock) { struct witness *w; if (witness_cold) panic("lock (%s) %s destroyed while witness_cold", lock->lo_class->lc_name, lock->lo_name); if ((lock->lo_flags & LO_INITIALIZED) == 0) panic("%s: lock (%s) %s is not initialized!\n", __func__, lock->lo_class->lc_name, lock->lo_name); if (lock->lo_flags & LO_LOCKED) panic("lock (%s) %s destroyed while held", lock->lo_class->lc_name, lock->lo_name); w = lock->lo_witness; if (w != NULL) { mtx_lock_spin(&w_mtx); w->w_refcount--; if (w->w_refcount == 0) { w->w_name = "(dead)"; w->w_file = "(dead)"; w->w_line = 0; } mtx_unlock_spin(&w_mtx); } mtx_lock(&all_mtx); lock_cur_cnt--; STAILQ_REMOVE(&all_locks, lock, lock_object, lo_list); lock->lo_flags &= LO_INITIALIZED; mtx_unlock(&all_mtx); } static void witness_display_list(void(*prnt)(const char *fmt, ...), struct witness_list *list) { struct witness *w, *w1; int found; STAILQ_FOREACH(w, list, w_typelist) { if (w->w_file == NULL) continue; found = 0; STAILQ_FOREACH(w1, list, w_typelist) { if (isitmychild(w1, w)) { found++; break; } } if (found) continue; /* * This lock has no anscestors, display its descendants. */ witness_displaydescendants(prnt, w); } } static void witness_display(void(*prnt)(const char *fmt, ...)) { struct witness *w; KASSERT(!witness_cold, ("%s: witness_cold\n", __func__)); witness_levelall(); /* * First, handle sleep locks which have been acquired at least * once. */ prnt("Sleep locks:\n"); witness_display_list(prnt, &w_sleep); /* * Now do spin locks which have been acquired at least once. */ prnt("\nSpin locks:\n"); witness_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) continue; prnt("%s\n", w->w_name); } } void witness_lock(struct lock_object *lock, int flags, const char *file, int line) { struct lock_list_entry **lock_list, *lle; struct lock_object *lock1, *lock2; struct lock_class *class; struct witness *w, *w1; struct proc *p; int i, j; #ifdef DDB int go_into_ddb = 0; #endif /* DDB */ if (witness_cold || witness_dead || lock->lo_witness == NULL || panicstr) return; w = lock->lo_witness; class = lock->lo_class; p = curproc; if ((lock->lo_flags & LO_LOCKED) == 0) panic("%s: lock (%s) %s is not locked @ %s:%d", __func__, class->lc_name, lock->lo_name, file, line); if ((lock->lo_flags & LO_RECURSED) != 0) { if ((lock->lo_flags & LO_RECURSABLE) == 0) panic( "%s: recursed on non-recursive lock (%s) %s @ %s:%d", __func__, class->lc_name, lock->lo_name, file, line); return; } /* * We have to hold a spinlock to keep lock_list valid across the check * in the LC_SLEEPLOCK case. In the LC_SPINLOCK case, it is already * protected by the spinlock we are currently performing the witness * checks on, so it is ok to release the lock after performing this * check. All we have to protect is the LC_SLEEPLOCK case when no * spinlocks are held as we may get preempted during this check and * lock_list could end up pointing to some other CPU's spinlock list. */ mtx_lock_spin(&w_mtx); lock_list = PCPU_PTR(spinlocks); if (class->lc_flags & LC_SLEEPLOCK) { if (*lock_list != NULL) { mtx_unlock_spin(&w_mtx); panic("blockable sleep lock (%s) %s @ %s:%d", class->lc_name, lock->lo_name, file, line); } lock_list = &p->p_sleeplocks; } mtx_unlock_spin(&w_mtx); if (flags & LOP_TRYLOCK) goto out; /* * Is this the first lock acquired? If so, then no order checking * is needed. */ if (*lock_list == NULL) goto out; /* * 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. */ lock1 = (*lock_list)->ll_children[(*lock_list)->ll_count - 1]; w1 = lock1->lo_witness; if (w1 == w) { if (w->w_same_squawked || dup_ok(w)) goto out; w->w_same_squawked = 1; printf("acquring duplicate lock of same type: \"%s\"\n", lock->lo_name); printf(" 1st @ %s:%d\n", w->w_file, w->w_line); printf(" 2nd @ %s:%d\n", file, line); #ifdef DDB go_into_ddb = 1; #endif /* DDB */ goto out; } MPASS(!mtx_owned(&w_mtx)); mtx_lock_spin(&w_mtx); /* * If we have a known higher number just say ok */ if (witness_watch > 1 && w->w_level > w1->w_level) { mtx_unlock_spin(&w_mtx); goto out; } if (isitmydescendant(w1, w)) { mtx_unlock_spin(&w_mtx); 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]; w1 = lock1->lo_witness; /* * If this lock doesn't undergo witness checking, * then skip it. */ if (w1 == NULL) { KASSERT((lock1->lo_flags & LO_WITNESS) == 0, ("lock missing witness structure")); continue; } if (!isitmydescendant(w, w1)) continue; /* * We have a lock order violation, check to see if it * is allowed or has already been yelled about. */ mtx_unlock_spin(&w_mtx); if (blessed(w, w1)) goto out; if (lock1 == &Giant.mtx_object) { if (w1->w_Giant_squawked) goto out; else w1->w_Giant_squawked = 1; } else { if (w1->w_other_squawked) goto out; else w1->w_other_squawked = 1; } /* * Ok, yell about it. */ 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 != NULL); if (lock2->lo_witness == w) break; i--; if (i == 0 && lle->ll_next != NULL) { lle = lle->ll_next; i = lle->ll_count - 1; MPASS(i != 0); } } while (i >= 0); if (i < 0) /* * We are very likely bogus in this case. */ printf(" 1st %s last acquired @ %s:%d\n", w->w_name, w->w_file, w->w_line); else printf(" 1st %p %s @ %s:%d\n", lock2, lock2->lo_name, lock2->lo_file, lock2->lo_line); printf(" 2nd %p %s @ %s:%d\n", lock1, lock1->lo_name, lock1->lo_file, lock1->lo_line); printf(" 3rd %p %s @ %s:%d\n", lock, lock->lo_name, file, line); #ifdef DDB go_into_ddb = 1; #endif /* DDB */ goto out; } } lock1 = (*lock_list)->ll_children[(*lock_list)->ll_count - 1]; if (!itismychild(lock1->lo_witness, w)) mtx_unlock_spin(&w_mtx); out: #ifdef DDB if (witness_ddb && go_into_ddb) Debugger("witness_enter"); #endif /* DDB */ w->w_file = file; w->w_line = line; lock->lo_line = line; lock->lo_file = file; lle = *lock_list; if (lle == NULL || lle->ll_count == LOCK_CHILDCOUNT) { *lock_list = witness_lock_list_get(); if (*lock_list == NULL) return; (*lock_list)->ll_next = lle; lle = *lock_list; } lle->ll_children[lle->ll_count++] = lock; } void witness_unlock(struct lock_object *lock, int flags, const char *file, int line) { struct lock_list_entry **lock_list, *lle; struct lock_class *class; struct proc *p; int i, j; if (witness_cold || witness_dead || lock->lo_witness == NULL || panicstr) return; p = curproc; class = lock->lo_class; if (lock->lo_flags & LO_RECURSED) { if ((lock->lo_flags & LO_LOCKED) == 0) panic("%s: recursed lock (%s) %s is not locked @ %s:%d", __func__, class->lc_name, lock->lo_name, file, line); return; } /* * We don't need to protect this PCPU_GET() here against preemption * because if we hold any spinlocks then we are already protected, * and if we don't we will get NULL if we hold no spinlocks even if * we switch CPU's while reading it. */ if (class->lc_flags & LC_SLEEPLOCK) { if ((flags & LOP_NOSWITCH) == 0 && PCPU_GET(spinlocks) != NULL) panic("switchable sleep unlock (%s) %s @ %s:%d", class->lc_name, lock->lo_name, file, line); lock_list = &p->p_sleeplocks; } else lock_list = PCPU_PTR(spinlocks); for (; *lock_list != NULL; lock_list = &(*lock_list)->ll_next) for (i = 0; i < (*lock_list)->ll_count; i++) if ((*lock_list)->ll_children[i] == lock) { (*lock_list)->ll_count--; for (j = i; j < (*lock_list)->ll_count; j++) (*lock_list)->ll_children[j] = (*lock_list)->ll_children[j + 1]; if ((*lock_list)->ll_count == 0) { lle = *lock_list; *lock_list = lle->ll_next; witness_lock_list_free(lle); } return; } } /* * Warn if any held locks are not sleepable. Note that Giant and the lock * passed in are both special cases since they are both released during the * sleep process and aren't actually held while the process is asleep. */ int witness_sleep(int check_only, struct lock_object *lock, const char *file, int line) { struct lock_list_entry **lock_list, *lle; struct lock_object *lock1; struct proc *p; critical_t savecrit; int i, n; if (witness_dead || panicstr) return (0); KASSERT(!witness_cold, ("%s: witness_cold\n", __func__)); n = 0; /* * Preemption bad because we need PCPU_PTR(spinlocks) to not change. */ savecrit = critical_enter(); p = curproc; lock_list = &p->p_sleeplocks; again: for (lle = *lock_list; lle != NULL; lle = lle->ll_next) for (i = lle->ll_count - 1; i >= 0; i--) { lock1 = lle->ll_children[i]; if (lock1 == lock || lock1 == &Giant.mtx_object || (lock1->lo_flags & LO_SLEEPABLE)) continue; n++; printf("%s:%d: %s with \"%s\" locked from %s:%d\n", file, line, check_only ? "could sleep" : "sleeping", lock1->lo_name, lock1->lo_file, lock1->lo_line); } if (lock_list == &p->p_sleeplocks) { lock_list = PCPU_PTR(spinlocks); goto again; } #ifdef DDB if (witness_ddb && n) Debugger("witness_sleep"); #endif /* DDB */ critical_exit(savecrit); return (n); } static struct witness * enroll(const char *description, struct lock_class *lock_class) { struct witness *w; if (!witness_watch) return (NULL); if ((lock_class->lc_flags & LC_SPINLOCK) && witness_skipspin) return (NULL); mtx_lock_spin(&w_mtx); STAILQ_FOREACH(w, &w_all, w_list) { if (strcmp(description, w->w_name) == 0) { 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); } } /* * This isn't quite right, as witness_cold is still 0 while we * enroll all the locks initialized before witness_initialize(). */ if ((lock_class->lc_flags & LC_SPINLOCK) && !witness_cold) { mtx_unlock_spin(&w_mtx); panic("spin lock %s not in order list", description); } if ((w = witness_get()) == NULL) return (NULL); 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); else if (lock_class->lc_flags & LC_SLEEPLOCK) STAILQ_INSERT_HEAD(&w_sleep, w, w_typelist); else { mtx_unlock_spin(&w_mtx); panic("lock class %s is not sleep or spin", lock_class->lc_name); } mtx_unlock_spin(&w_mtx); return (w); } static int itismychild(struct witness *parent, struct witness *child) { static int recursed; struct witness_child_list_entry **wcl; struct witness_list *list; MPASS(child != NULL && parent != NULL); if ((parent->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK)) != (child->w_class->lc_flags & (LC_SLEEPLOCK | LC_SPINLOCK))) panic( "%s: parent (%s) and child (%s) are not the same lock type", __func__, parent->w_class->lc_name, child->w_class->lc_name); /* * Insert "child" after "parent" */ wcl = &parent->w_children; while (*wcl != NULL && (*wcl)->wcl_count == WITNESS_NCHILDREN) wcl = &(*wcl)->wcl_next; if (*wcl == NULL) { *wcl = witness_child_get(); if (*wcl == NULL) return (1); } (*wcl)->wcl_children[(*wcl)->wcl_count++] = child; /* * Now prune whole tree. We look for cases where a lock is now * both a descendant and a direct child of a given lock. In that * case, we want to remove the direct child link from the tree. */ if (recursed) return (0); recursed = 1; if (parent->w_class->lc_flags & LC_SLEEPLOCK) list = &w_sleep; else list = &w_spin; STAILQ_FOREACH(child, list, w_typelist) { STAILQ_FOREACH(parent, list, w_typelist) { if (!isitmychild(parent, child)) continue; removechild(parent, child); if (isitmydescendant(parent, child)) continue; itismychild(parent, child); } } recursed = 0; witness_levelall(); return (0); } static void removechild(struct witness *parent, struct witness *child) { struct witness_child_list_entry **wcl, *wcl1; int i; for (wcl = &parent->w_children; *wcl != NULL; wcl = &(*wcl)->wcl_next) for (i = 0; i < (*wcl)->wcl_count; i++) if ((*wcl)->wcl_children[i] == child) goto found; return; found: (*wcl)->wcl_count--; if ((*wcl)->wcl_count > i) (*wcl)->wcl_children[i] = (*wcl)->wcl_children[(*wcl)->wcl_count]; MPASS((*wcl)->wcl_children[i] != NULL); if ((*wcl)->wcl_count != 0) return; wcl1 = *wcl; *wcl = wcl1->wcl_next; witness_child_free(wcl1); } static int isitmychild(struct witness *parent, struct witness *child) { struct witness_child_list_entry *wcl; int i; for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { for (i = 0; i < wcl->wcl_count; i++) { if (wcl->wcl_children[i] == child) return (1); } } return (0); } static int isitmydescendant(struct witness *parent, struct witness *child) { struct witness_child_list_entry *wcl; int i, j; if (isitmychild(parent, child)) return (1); j = 0; for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) { MPASS(j < 1000); for (i = 0; i < wcl->wcl_count; i++) { if (isitmydescendant(wcl->wcl_children[i], child)) return (1); } j++; } return (0); } void witness_levelall (void) { struct witness_list *list; struct witness *w, *w1; /* * First clear all levels. */ STAILQ_FOREACH(w, &w_all, w_list) { w->w_level = 0; } /* * Look for locks with no parent and level all their descendants. */ STAILQ_FOREACH(w, &w_all, w_list) { /* * This is just an optimization, technically we could get * away just walking the all list each time. */ if (w->w_class->lc_flags & LC_SLEEPLOCK) list = &w_sleep; else list = &w_spin; STAILQ_FOREACH(w1, list, w_typelist) { if (isitmychild(w1, w)) goto skip; } witness_leveldescendents(w, 0); skip: } } static void witness_leveldescendents(struct witness *parent, int level) { struct witness_child_list_entry *wcl; int i; if (parent->w_level < level) parent->w_level = level; level++; for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) for (i = 0; i < wcl->wcl_count; i++) witness_leveldescendents(wcl->wcl_children[i], level); } static void witness_displaydescendants(void(*prnt)(const char *fmt, ...), struct witness *parent) { struct witness_child_list_entry *wcl; int i, level; level = parent->w_level; prnt("%-2d", level); for (i = 0; i < level; i++) prnt(" "); prnt("%s", parent->w_name); if (parent->w_file != NULL) prnt(" -- last acquired @ %s:%d\n", parent->w_file, parent->w_line); for (wcl = parent->w_children; wcl != NULL; wcl = wcl->wcl_next) for (i = 0; i < wcl->wcl_count; i++) witness_displaydescendants(prnt, wcl->wcl_children[i]); } static int dup_ok(struct witness *w) { const char **dup; for (dup = dup_list; *dup != NULL; dup++) if (strcmp(w->w_name, *dup) == 0) return (1); return (0); } 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); } static struct witness * witness_get(void) { struct witness *w; if (STAILQ_EMPTY(&w_free)) { witness_dead = 1; mtx_unlock_spin(&w_mtx); printf("%s: witness exhausted\n", __func__); return (NULL); } w = STAILQ_FIRST(&w_free); STAILQ_REMOVE_HEAD(&w_free, w_list); bzero(w, sizeof(*w)); return (w); } static void witness_free(struct witness *w) { STAILQ_INSERT_HEAD(&w_free, w, w_list); } static struct witness_child_list_entry * witness_child_get(void) { struct witness_child_list_entry *wcl; wcl = w_child_free; if (wcl == NULL) { witness_dead = 1; mtx_unlock_spin(&w_mtx); printf("%s: witness exhausted\n", __func__); return (NULL); } w_child_free = wcl->wcl_next; bzero(wcl, sizeof(*wcl)); return (wcl); } static void witness_child_free(struct witness_child_list_entry *wcl) { wcl->wcl_next = w_child_free; w_child_free = wcl; } static struct lock_list_entry * witness_lock_list_get(void) { struct lock_list_entry *lle; mtx_lock_spin(&w_mtx); lle = w_lock_list_free; if (lle == NULL) { witness_dead = 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); } int witness_list_locks(struct lock_list_entry **lock_list) { struct lock_list_entry *lle; struct lock_object *lock; int i, nheld; nheld = 0; for (lle = *lock_list; lle != NULL; lle = lle->ll_next) for (i = lle->ll_count - 1; i >= 0; i--) { lock = lle->ll_children[i]; printf("\t(%s) %s (%p) locked at %s:%d\n", lock->lo_class->lc_name, lock->lo_name, lock, lock->lo_file, lock->lo_line); nheld++; } return (nheld); } /* * Calling this on p != curproc is bad unless we are in ddb. */ int witness_list(struct proc *p) { critical_t savecrit; int nheld; KASSERT(p == curproc || db_active, ("%s: p != curproc and we aren't in the debugger", __func__)); KASSERT(!witness_cold, ("%s: witness_cold", __func__)); nheld = witness_list_locks(&p->p_sleeplocks); /* * We only handle spinlocks if p == curproc. This is somewhat broken * if p 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 p->p_oncpu to * get the list of spinlocks for this process and "fix" this. */ if (p == curproc) { /* * Preemption bad because we need PCPU_PTR(spinlocks) to not * change. */ savecrit = critical_enter(); nheld += witness_list_locks(PCPU_PTR(spinlocks)); critical_exit(savecrit); } return (nheld); } void witness_save(struct lock_object *lock, const char **filep, int *linep) { KASSERT(!witness_cold, ("%s: witness_cold\n", __func__)); if (lock->lo_witness == NULL) return; *filep = lock->lo_file; *linep = lock->lo_line; } void witness_restore(struct lock_object *lock, const char *file, int line) { KASSERT(!witness_cold, ("%s: witness_cold\n", __func__)); if (lock->lo_witness == NULL) return; lock->lo_witness->w_file = file; lock->lo_witness->w_line = line; lock->lo_file = file; lock->lo_line = line; } #ifdef DDB DB_SHOW_COMMAND(locks, db_witness_list) { struct proc *p; pid_t pid; if (have_addr) { pid = (addr % 16) + ((addr >> 4) % 16) * 10 + ((addr >> 8) % 16) * 100 + ((addr >> 12) % 16) * 1000 + ((addr >> 16) % 16) * 10000; /* sx_slock(&allproc_lock); */ LIST_FOREACH(p, &allproc, p_list) { if (p->p_pid == pid) break; } /* sx_sunlock(&allproc_lock); */ if (p == NULL) { db_printf("pid %d not found\n", pid); return; } } else p = curproc; witness_list(p); } DB_SHOW_COMMAND(witness, db_witness_display) { witness_display(db_printf); } #endif