/*- * 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 $ * $FreeBSD$ */ /* * 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" /* * Cause non-inlined mtx_*() to be compiled. * Must be defined early because other system headers may include mutex.h. */ #define _KERN_MUTEX_C_ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Machine independent bits of the mutex implementation */ /* All mutexes in system (used for debug/panic) */ #ifdef WITNESS static struct mtx_debug all_mtx_debug = { NULL, {NULL, NULL}, NULL, 0, "All mutexes queue head" }; static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, &all_mtx_debug, TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), { NULL, NULL }, &all_mtx, &all_mtx }; #else /* WITNESS */ static struct mtx all_mtx = { MTX_UNOWNED, 0, 0, "All mutexes queue head", TAILQ_HEAD_INITIALIZER(all_mtx.mtx_blocked), { NULL, NULL }, &all_mtx, &all_mtx }; #endif /* WITNESS */ static int mtx_cur_cnt; static int mtx_max_cnt; void _mtx_enter_giant_def(void); void _mtx_exit_giant_def(void); static void propagate_priority(struct proc *); #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) #define mtx_owner(m) (mtx_unowned(m) ? NULL \ : (struct proc *)((m)->mtx_lock & MTX_FLAGMASK)) #define RETIP(x) *(((uintptr_t *)(&x)) - 1) #define SET_PRIO(p, pri) (p)->p_priority = (pri) /* * XXX Temporary, for use from assembly language */ void _mtx_enter_giant_def(void) { mtx_enter(&Giant, MTX_DEF); } void _mtx_exit_giant_def(void) { mtx_exit(&Giant, MTX_DEF); } static void propagate_priority(struct proc *p) { int pri = p->p_priority; struct mtx *m = p->p_blocked; mtx_assert(&sched_lock, MA_OWNED); for (;;) { struct proc *p1; p = mtx_owner(m); if (p == NULL) { /* * This really isn't quite right. Really * ought to bump priority of process that * next acquires the mutex. */ MPASS(m->mtx_lock == MTX_CONTESTED); return; } MPASS(p->p_magic == P_MAGIC); KASSERT(p->p_stat != SSLEEP, ("sleeping process owns a mutex")); if (p->p_priority <= pri) return; /* * Bump this process' priority. */ SET_PRIO(p, pri); /* * If lock holder is actually running, just bump priority. */ #ifdef SMP /* * For SMP, we can check the p_oncpu field to see if we are * running. */ if (p->p_oncpu != 0xff) { MPASS(p->p_stat == SRUN || p->p_stat == SZOMB); return; } #else /* * For UP, we check to see if p is curproc (this shouldn't * ever happen however as it would mean we are in a deadlock.) */ if (p == curproc) { panic("Deadlock detected"); return; } #endif /* * If on run queue move to new run queue, and * quit. */ if (p->p_stat == SRUN) { printf("XXX: moving process %d(%s) to a new run queue\n", p->p_pid, p->p_comm); MPASS(p->p_blocked == NULL); remrunqueue(p); setrunqueue(p); return; } /* * If we aren't blocked on a mutex, we should be. */ KASSERT(p->p_stat == SMTX, ( "process %d(%s):%d holds %s but isn't blocked on a mutex\n", p->p_pid, p->p_comm, p->p_stat, m->mtx_description)); /* * Pick up the mutex that p is blocked on. */ m = p->p_blocked; MPASS(m != NULL); printf("XXX: process %d(%s) is blocked on %s\n", p->p_pid, p->p_comm, m->mtx_description); /* * Check if the proc needs to be moved up on * the blocked chain */ if (p == TAILQ_FIRST(&m->mtx_blocked)) { printf("XXX: process at head of run queue\n"); continue; } p1 = TAILQ_PREV(p, rq, p_procq); if (p1->p_priority <= pri) { printf( "XXX: previous process %d(%s) has higher priority\n", p->p_pid, p->p_comm); continue; } /* * Remove proc from blocked chain and determine where * it should be moved up to. Since we know that p1 has * a lower priority than p, we know that at least one * process in the chain has a lower priority and that * p1 will thus not be NULL after the loop. */ TAILQ_REMOVE(&m->mtx_blocked, p, p_procq); TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) { MPASS(p1->p_magic == P_MAGIC); if (p1->p_priority > pri) break; } MPASS(p1 != NULL); TAILQ_INSERT_BEFORE(p1, p, p_procq); CTR4(KTR_LOCK, "propagate_priority: p 0x%p moved before 0x%p on [0x%p] %s", p, p1, m, m->mtx_description); } } void mtx_enter_hard(struct mtx *m, int type, int saveintr) { struct proc *p = CURPROC; KASSERT(p != NULL, ("curproc is NULL in mutex")); switch (type) { case MTX_DEF: if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)p) { m->mtx_recurse++; atomic_set_ptr(&m->mtx_lock, MTX_RECURSE); if ((type & MTX_QUIET) == 0) CTR1(KTR_LOCK, "mtx_enter: 0x%p recurse", m); return; } if ((type & MTX_QUIET) == 0) CTR3(KTR_LOCK, "mtx_enter: 0x%p contested (lock=%p) [0x%p]", m, (void *)m->mtx_lock, (void *)RETIP(m)); /* * Save our priority. Even though p_nativepri is protected * by sched_lock, we don't obtain it here as it can be * expensive. Since this is the only place p_nativepri is * set, and since two CPUs will not be executing the same * process concurrently, we know that no other CPU is going * to be messing with this. Also, p_nativepri is only read * when we are blocked on a mutex, so that can't be happening * right now either. */ p->p_nativepri = p->p_priority; while (!_obtain_lock(m, p)) { uintptr_t v; struct proc *p1; mtx_enter(&sched_lock, MTX_SPIN | MTX_RLIKELY); /* * check if the lock has been released while * waiting for the schedlock. */ if ((v = m->mtx_lock) == MTX_UNOWNED) { mtx_exit(&sched_lock, MTX_SPIN); continue; } /* * The mutex was marked contested on release. This * means that there are processes blocked on it. */ if (v == MTX_CONTESTED) { p1 = TAILQ_FIRST(&m->mtx_blocked); KASSERT(p1 != NULL, ("contested mutex has no contesters")); KASSERT(p != NULL, ("curproc is NULL for contested mutex")); m->mtx_lock = (uintptr_t)p | MTX_CONTESTED; if (p1->p_priority < p->p_priority) { SET_PRIO(p, p1->p_priority); } mtx_exit(&sched_lock, MTX_SPIN); return; } /* * If the mutex isn't already contested and * a failure occurs setting the contested bit the * mutex was either release or the * state of the RECURSION bit changed. */ if ((v & MTX_CONTESTED) == 0 && !atomic_cmpset_ptr(&m->mtx_lock, (void *)v, (void *)(v | MTX_CONTESTED))) { mtx_exit(&sched_lock, MTX_SPIN); continue; } /* We definitely have to sleep for this lock */ mtx_assert(m, MA_NOTOWNED); #ifdef notyet /* * If we're borrowing an interrupted thread's VM * context must clean up before going to sleep. */ if (p->p_flag & (P_ITHD | P_SITHD)) { ithd_t *it = (ithd_t *)p; if (it->it_interrupted) { if ((type & MTX_QUIET) == 0) CTR2(KTR_LOCK, "mtx_enter: 0x%x interrupted 0x%x", it, it->it_interrupted); intr_thd_fixup(it); } } #endif /* Put us on the list of procs blocked on this mutex */ if (TAILQ_EMPTY(&m->mtx_blocked)) { p1 = (struct proc *)(m->mtx_lock & MTX_FLAGMASK); LIST_INSERT_HEAD(&p1->p_contested, m, mtx_contested); TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); } else { TAILQ_FOREACH(p1, &m->mtx_blocked, p_procq) if (p1->p_priority > p->p_priority) break; if (p1) TAILQ_INSERT_BEFORE(p1, p, p_procq); else TAILQ_INSERT_TAIL(&m->mtx_blocked, p, p_procq); } p->p_blocked = m; /* Who we're blocked on */ p->p_mtxname = m->mtx_description; p->p_stat = SMTX; #if 0 propagate_priority(p); #endif if ((type & MTX_QUIET) == 0) CTR3(KTR_LOCK, "mtx_enter: p 0x%p blocked on [0x%p] %s", p, m, m->mtx_description); mi_switch(); if ((type & MTX_QUIET) == 0) CTR3(KTR_LOCK, "mtx_enter: p 0x%p free from blocked on [0x%p] %s", p, m, m->mtx_description); mtx_exit(&sched_lock, MTX_SPIN); } return; case MTX_SPIN: case MTX_SPIN | MTX_FIRST: case MTX_SPIN | MTX_TOPHALF: { int i = 0; if (m->mtx_lock == (uintptr_t)p) { m->mtx_recurse++; return; } if ((type & MTX_QUIET) == 0) CTR1(KTR_LOCK, "mtx_enter: %p spinning", m); for (;;) { if (_obtain_lock(m, p)) break; while (m->mtx_lock != MTX_UNOWNED) { if (i++ < 1000000) continue; if (i++ < 6000000) DELAY (1); #ifdef DDB else if (!db_active) #else else #endif panic( "spin lock %s held by 0x%p for > 5 seconds", m->mtx_description, (void *)m->mtx_lock); } } #ifdef MUTEX_DEBUG if (type != MTX_SPIN) m->mtx_saveintr = 0xbeefface; else #endif m->mtx_saveintr = saveintr; if ((type & MTX_QUIET) == 0) CTR1(KTR_LOCK, "mtx_enter: 0x%p spin done", m); return; } } } void mtx_exit_hard(struct mtx *m, int type) { struct proc *p, *p1; struct mtx *m1; int pri; p = CURPROC; switch (type) { case MTX_DEF: case MTX_DEF | MTX_NOSWITCH: if (m->mtx_recurse != 0) { if (--(m->mtx_recurse) == 0) atomic_clear_ptr(&m->mtx_lock, MTX_RECURSE); if ((type & MTX_QUIET) == 0) CTR1(KTR_LOCK, "mtx_exit: 0x%p unrecurse", m); return; } mtx_enter(&sched_lock, MTX_SPIN); if ((type & MTX_QUIET) == 0) CTR1(KTR_LOCK, "mtx_exit: 0x%p contested", m); p1 = TAILQ_FIRST(&m->mtx_blocked); MPASS(p->p_magic == P_MAGIC); MPASS(p1->p_magic == P_MAGIC); TAILQ_REMOVE(&m->mtx_blocked, p1, p_procq); if (TAILQ_EMPTY(&m->mtx_blocked)) { LIST_REMOVE(m, mtx_contested); _release_lock_quick(m); if ((type & MTX_QUIET) == 0) CTR1(KTR_LOCK, "mtx_exit: 0x%p not held", m); } else atomic_store_rel_ptr(&m->mtx_lock, (void *)MTX_CONTESTED); pri = MAXPRI; LIST_FOREACH(m1, &p->p_contested, mtx_contested) { int cp = TAILQ_FIRST(&m1->mtx_blocked)->p_priority; if (cp < pri) pri = cp; } if (pri > p->p_nativepri) pri = p->p_nativepri; SET_PRIO(p, pri); if ((type & MTX_QUIET) == 0) CTR2(KTR_LOCK, "mtx_exit: 0x%p contested setrunqueue 0x%p", m, p1); p1->p_blocked = NULL; p1->p_mtxname = NULL; p1->p_stat = SRUN; setrunqueue(p1); if ((type & MTX_NOSWITCH) == 0 && p1->p_priority < pri) { #ifdef notyet if (p->p_flag & (P_ITHD | P_SITHD)) { ithd_t *it = (ithd_t *)p; if (it->it_interrupted) { if ((type & MTX_QUIET) == 0) CTR2(KTR_LOCK, "mtx_exit: 0x%x interruped 0x%x", it, it->it_interrupted); intr_thd_fixup(it); } } #endif setrunqueue(p); if ((type & MTX_QUIET) == 0) CTR2(KTR_LOCK, "mtx_exit: 0x%p switching out lock=0x%p", m, (void *)m->mtx_lock); mi_switch(); if ((type & MTX_QUIET) == 0) CTR2(KTR_LOCK, "mtx_exit: 0x%p resuming lock=0x%p", m, (void *)m->mtx_lock); } mtx_exit(&sched_lock, MTX_SPIN); break; case MTX_SPIN: case MTX_SPIN | MTX_FIRST: if (m->mtx_recurse != 0) { m->mtx_recurse--; return; } MPASS(mtx_owned(m)); _release_lock_quick(m); if (type & MTX_FIRST) enable_intr(); /* XXX is this kosher? */ else { MPASS(m->mtx_saveintr != 0xbeefface); restore_intr(m->mtx_saveintr); } break; case MTX_SPIN | MTX_TOPHALF: if (m->mtx_recurse != 0) { m->mtx_recurse--; return; } MPASS(mtx_owned(m)); _release_lock_quick(m); break; default: panic("mtx_exit_hard: unsupported type 0x%x\n", type); } } #define MV_DESTROY 0 /* validate before destory */ #define MV_INIT 1 /* validate before init */ #ifdef MUTEX_DEBUG int mtx_validate __P((struct mtx *, int)); int mtx_validate(struct mtx *m, int when) { struct mtx *mp; int i; int retval = 0; if (m == &all_mtx || cold) return 0; mtx_enter(&all_mtx, MTX_DEF); /* * XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly * we can re-enable the kernacc() checks. */ #ifndef __alpha__ MPASS(kernacc((caddr_t)all_mtx.mtx_next, sizeof(uintptr_t), VM_PROT_READ) == 1); #endif MPASS(all_mtx.mtx_next->mtx_prev == &all_mtx); for (i = 0, mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) { #ifndef __alpha__ if (kernacc((caddr_t)mp->mtx_next, sizeof(uintptr_t), VM_PROT_READ) != 1) { panic("mtx_validate: mp=%p mp->mtx_next=%p", mp, mp->mtx_next); } #endif i++; if (i > mtx_cur_cnt) { panic("mtx_validate: too many in chain, known=%d\n", mtx_cur_cnt); } } MPASS(i == mtx_cur_cnt); switch (when) { case MV_DESTROY: for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) if (mp == m) break; MPASS(mp == m); break; case MV_INIT: for (mp = all_mtx.mtx_next; mp != &all_mtx; mp = mp->mtx_next) if (mp == m) { /* * Not good. This mutex already exists. */ printf("re-initing existing mutex %s\n", m->mtx_description); MPASS(m->mtx_lock == MTX_UNOWNED); retval = 1; } } mtx_exit(&all_mtx, MTX_DEF); return (retval); } #endif void mtx_init(struct mtx *m, const char *t, int flag) { #ifdef WITNESS struct mtx_debug *debug; #endif if ((flag & MTX_QUIET) == 0) CTR2(KTR_LOCK, "mtx_init 0x%p (%s)", m, t); #ifdef MUTEX_DEBUG if (mtx_validate(m, MV_INIT)) /* diagnostic and error correction */ return; #endif #ifdef WITNESS if (flag & MTX_COLD) debug = m->mtx_debug; else debug = NULL; if (debug == NULL) { #ifdef DIAGNOSTIC if(cold && bootverbose) printf("malloc'ing mtx_debug while cold for %s\n", t); #endif /* XXX - should not use DEVBUF */ debug = malloc(sizeof(struct mtx_debug), M_DEVBUF, M_NOWAIT | M_ZERO); MPASS(debug != NULL); } #endif bzero((void *)m, sizeof *m); TAILQ_INIT(&m->mtx_blocked); #ifdef WITNESS m->mtx_debug = debug; #endif m->mtx_description = t; m->mtx_lock = MTX_UNOWNED; /* Put on all mutex queue */ mtx_enter(&all_mtx, MTX_DEF); m->mtx_next = &all_mtx; m->mtx_prev = all_mtx.mtx_prev; m->mtx_prev->mtx_next = m; all_mtx.mtx_prev = m; if (++mtx_cur_cnt > mtx_max_cnt) mtx_max_cnt = mtx_cur_cnt; mtx_exit(&all_mtx, MTX_DEF); witness_init(m, flag); } void mtx_destroy(struct mtx *m) { CTR2(KTR_LOCK, "mtx_destroy 0x%p (%s)", m, m->mtx_description); #ifdef MUTEX_DEBUG if (m->mtx_next == NULL) panic("mtx_destroy: %p (%s) already destroyed", m, m->mtx_description); if (!mtx_owned(m)) { MPASS(m->mtx_lock == MTX_UNOWNED); } else { MPASS((m->mtx_lock & (MTX_RECURSE|MTX_CONTESTED)) == 0); } mtx_validate(m, MV_DESTROY); /* diagnostic */ #endif #ifdef WITNESS if (m->mtx_witness) witness_destroy(m); #endif /* WITNESS */ /* Remove from the all mutex queue */ mtx_enter(&all_mtx, MTX_DEF); m->mtx_next->mtx_prev = m->mtx_prev; m->mtx_prev->mtx_next = m->mtx_next; #ifdef MUTEX_DEBUG m->mtx_next = m->mtx_prev = NULL; #endif #ifdef WITNESS free(m->mtx_debug, M_DEVBUF); m->mtx_debug = NULL; #endif mtx_cur_cnt--; mtx_exit(&all_mtx, MTX_DEF); } /* * The non-inlined versions of the mtx_*() functions are always built (above), * but the witness code depends on the WITNESS kernel option being specified. */ #ifdef WITNESS #define WITNESS_COUNT 200 #define WITNESS_NCHILDREN 2 int witness_watch = 1; struct witness { struct witness *w_next; const char *w_description; const char *w_file; int w_line; struct witness *w_morechildren; u_char w_childcnt; u_char w_Giant_squawked:1; u_char w_other_squawked:1; u_char w_same_squawked:1; u_char w_sleep:1; u_char w_spin:1; /* this is a spin mutex */ u_int w_level; struct witness *w_children[WITNESS_NCHILDREN]; }; struct witness_blessed { char *b_lock1; char *b_lock2; }; #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. */ #ifdef WITNESS_DDB int witness_ddb = 1; #else int witness_ddb = 0; #endif SYSCTL_INT(_debug, OID_AUTO, witness_ddb, CTLFLAG_RW, &witness_ddb, 0, ""); #endif /* DDB */ #ifdef WITNESS_SKIPSPIN int witness_skipspin = 1; #else int witness_skipspin = 0; #endif SYSCTL_INT(_debug, OID_AUTO, witness_skipspin, CTLFLAG_RD, &witness_skipspin, 0, ""); MUTEX_DECLARE(static,w_mtx); static struct witness *w_free; static struct witness *w_all; static int w_inited; static int witness_dead; /* fatal error, probably no memory */ static struct witness w_data[WITNESS_COUNT]; static struct witness *enroll __P((const char *description, int flag)); static int itismychild __P((struct witness *parent, struct witness *child)); static void removechild __P((struct witness *parent, struct witness *child)); static int isitmychild __P((struct witness *parent, struct witness *child)); static int isitmydescendant __P((struct witness *parent, struct witness *child)); static int dup_ok __P((struct witness *)); static int blessed __P((struct witness *, struct witness *)); static void witness_displaydescendants __P((void(*)(const char *fmt, ...), struct witness *)); static void witness_leveldescendents __P((struct witness *parent, int level)); static void witness_levelall __P((void)); static struct witness * witness_get __P((void)); static void witness_free __P((struct witness *m)); static char *ignore_list[] = { "witness lock", NULL }; static char *spin_order_list[] = { "sio", "sched lock", #ifdef __i386__ "clk", #endif "callout", /* * leaf locks */ NULL }; static char *order_list[] = { "uidinfo hash", "uidinfo struct", NULL, NULL }; static char *dup_list[] = { NULL }; static char *sleep_list[] = { "Giant", 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); void witness_init(struct mtx *m, int flag) { m->mtx_witness = enroll(m->mtx_description, flag); } void witness_destroy(struct mtx *m) { struct mtx *m1; struct proc *p; p = CURPROC; for ((m1 = LIST_FIRST(&p->p_heldmtx)); m1 != NULL; m1 = LIST_NEXT(m1, mtx_held)) { if (m1 == m) { LIST_REMOVE(m, mtx_held); break; } } return; } void witness_enter(struct mtx *m, int flags, const char *file, int line) { struct witness *w, *w1; struct mtx *m1; struct proc *p; int i; #ifdef DDB int go_into_ddb = 0; #endif /* DDB */ if (panicstr) return; w = m->mtx_witness; p = CURPROC; if (flags & MTX_SPIN) { if (!w->w_spin) panic("mutex_enter: MTX_SPIN on MTX_DEF mutex %s @" " %s:%d", m->mtx_description, file, line); if (m->mtx_recurse != 0) return; mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); i = PCPU_GET(witness_spin_check); if (i != 0 && w->w_level < i) { mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); panic("mutex_enter(%s:%x, MTX_SPIN) out of order @" " %s:%d already holding %s:%x", m->mtx_description, w->w_level, file, line, spin_order_list[ffs(i)-1], i); } PCPU_SET(witness_spin_check, i | w->w_level); mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); w->w_file = file; w->w_line = line; m->mtx_line = line; m->mtx_file = file; return; } if (w->w_spin) panic("mutex_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", m->mtx_description, file, line); if (m->mtx_recurse != 0) return; if (witness_dead) goto out; if (cold) goto out; if (!mtx_legal2block()) panic("blockable mtx_enter() of %s when not legal @ %s:%d", m->mtx_description, file, line); /* * Is this the first mutex acquired */ if ((m1 = LIST_FIRST(&p->p_heldmtx)) == NULL) goto out; if ((w1 = m1->mtx_witness) == 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", m->mtx_description); 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_enter(&w_mtx, MTX_SPIN | MTX_QUIET); /* * If we have a known higher number just say ok */ if (witness_watch > 1 && w->w_level > w1->w_level) { mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); goto out; } if (isitmydescendant(m1->mtx_witness, w)) { mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); goto out; } for (i = 0; m1 != NULL; m1 = LIST_NEXT(m1, mtx_held), i++) { MPASS(i < 200); w1 = m1->mtx_witness; if (isitmydescendant(w, w1)) { mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); if (blessed(w, w1)) goto out; if (m1 == &Giant) { 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; } printf("lock order reversal\n"); printf(" 1st %s last acquired @ %s:%d\n", w->w_description, w->w_file, w->w_line); printf(" 2nd %p %s @ %s:%d\n", m1, w1->w_description, w1->w_file, w1->w_line); printf(" 3rd %p %s @ %s:%d\n", m, w->w_description, file, line); #ifdef DDB go_into_ddb = 1; #endif /* DDB */ goto out; } } m1 = LIST_FIRST(&p->p_heldmtx); if (!itismychild(m1->mtx_witness, w)) mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); out: #ifdef DDB if (witness_ddb && go_into_ddb) Debugger("witness_enter"); #endif /* DDB */ w->w_file = file; w->w_line = line; m->mtx_line = line; m->mtx_file = file; /* * If this pays off it likely means that a mutex being witnessed * is acquired in hardclock. Put it in the ignore list. It is * likely not the mutex this assert fails on. */ MPASS(m->mtx_held.le_prev == NULL); LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held); } void witness_exit(struct mtx *m, int flags, const char *file, int line) { struct witness *w; if (panicstr) return; w = m->mtx_witness; if (flags & MTX_SPIN) { if (!w->w_spin) panic("mutex_exit: MTX_SPIN on MTX_DEF mutex %s @" " %s:%d", m->mtx_description, file, line); if (m->mtx_recurse != 0) return; mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); PCPU_SET(witness_spin_check, PCPU_GET(witness_spin_check) & ~w->w_level); mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); return; } if (w->w_spin) panic("mutex_exit: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", m->mtx_description, file, line); if (m->mtx_recurse != 0) return; if ((flags & MTX_NOSWITCH) == 0 && !mtx_legal2block() && !cold) panic("switchable mtx_exit() of %s when not legal @ %s:%d", m->mtx_description, file, line); LIST_REMOVE(m, mtx_held); m->mtx_held.le_prev = NULL; } void witness_try_enter(struct mtx *m, int flags, const char *file, int line) { struct proc *p; struct witness *w = m->mtx_witness; if (panicstr) return; if (flags & MTX_SPIN) { if (!w->w_spin) panic("mutex_try_enter: " "MTX_SPIN on MTX_DEF mutex %s @ %s:%d", m->mtx_description, file, line); if (m->mtx_recurse != 0) return; mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); PCPU_SET(witness_spin_check, PCPU_GET(witness_spin_check) | w->w_level); mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); w->w_file = file; w->w_line = line; m->mtx_line = line; m->mtx_file = file; return; } if (w->w_spin) panic("mutex_try_enter: MTX_DEF on MTX_SPIN mutex %s @ %s:%d", m->mtx_description, file, line); if (m->mtx_recurse != 0) return; w->w_file = file; w->w_line = line; m->mtx_line = line; m->mtx_file = file; p = CURPROC; MPASS(m->mtx_held.le_prev == NULL); LIST_INSERT_HEAD(&p->p_heldmtx, (struct mtx*)m, mtx_held); } void witness_display(void(*prnt)(const char *fmt, ...)) { struct witness *w, *w1; witness_levelall(); for (w = w_all; w; w = w->w_next) { if (w->w_file == NULL) continue; for (w1 = w_all; w1; w1 = w1->w_next) { if (isitmychild(w1, w)) break; } if (w1 != NULL) continue; /* * This lock has no anscestors, display its descendants. */ witness_displaydescendants(prnt, w); } prnt("\nMutex which were never acquired\n"); for (w = w_all; w; w = w->w_next) { if (w->w_file != NULL) continue; prnt("%s\n", w->w_description); } } int witness_sleep(int check_only, struct mtx *mtx, const char *file, int line) { struct mtx *m; struct proc *p; char **sleep; int n = 0; p = CURPROC; for ((m = LIST_FIRST(&p->p_heldmtx)); m != NULL; m = LIST_NEXT(m, mtx_held)) { if (m == mtx) continue; for (sleep = sleep_list; *sleep!= NULL; sleep++) if (strcmp(m->mtx_description, *sleep) == 0) goto next; printf("%s:%d: %s with \"%s\" locked from %s:%d\n", file, line, check_only ? "could sleep" : "sleeping", m->mtx_description, m->mtx_witness->w_file, m->mtx_witness->w_line); n++; next: } #ifdef DDB if (witness_ddb && n) Debugger("witness_sleep"); #endif /* DDB */ return (n); } static struct witness * enroll(const char *description, int flag) { int i; struct witness *w, *w1; char **ignore; char **order; if (!witness_watch) return (NULL); for (ignore = ignore_list; *ignore != NULL; ignore++) if (strcmp(description, *ignore) == 0) return (NULL); if (w_inited == 0) { mtx_init(&w_mtx, "witness lock", MTX_COLD | MTX_SPIN); for (i = 0; i < WITNESS_COUNT; i++) { w = &w_data[i]; witness_free(w); } w_inited = 1; for (order = order_list; *order != NULL; order++) { w = enroll(*order, MTX_DEF); w->w_file = "order list"; for (order++; *order != NULL; order++) { w1 = enroll(*order, MTX_DEF); w1->w_file = "order list"; itismychild(w, w1); w = w1; } } } if ((flag & MTX_SPIN) && witness_skipspin) return (NULL); mtx_enter(&w_mtx, MTX_SPIN | MTX_QUIET); for (w = w_all; w; w = w->w_next) { if (strcmp(description, w->w_description) == 0) { mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); return (w); } } if ((w = witness_get()) == NULL) return (NULL); w->w_next = w_all; w_all = w; w->w_description = description; mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); if (flag & MTX_SPIN) { w->w_spin = 1; i = 1; for (order = spin_order_list; *order != NULL; order++) { if (strcmp(description, *order) == 0) break; i <<= 1; } if (*order == NULL) panic("spin lock %s not in order list", description); w->w_level = i; } return (w); } static int itismychild(struct witness *parent, struct witness *child) { static int recursed; /* * Insert "child" after "parent" */ while (parent->w_morechildren) parent = parent->w_morechildren; if (parent->w_childcnt == WITNESS_NCHILDREN) { if ((parent->w_morechildren = witness_get()) == NULL) return (1); parent = parent->w_morechildren; } MPASS(child != NULL); parent->w_children[parent->w_childcnt++] = child; /* * now prune whole tree */ if (recursed) return (0); recursed = 1; for (child = w_all; child != NULL; child = child->w_next) { for (parent = w_all; parent != NULL; parent = parent->w_next) { 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 *w, *w1; int i; for (w = parent; w != NULL; w = w->w_morechildren) for (i = 0; i < w->w_childcnt; i++) if (w->w_children[i] == child) goto found; return; found: for (w1 = w; w1->w_morechildren != NULL; w1 = w1->w_morechildren) continue; w->w_children[i] = w1->w_children[--w1->w_childcnt]; MPASS(w->w_children[i] != NULL); if (w1->w_childcnt != 0) return; if (w1 == parent) return; for (w = parent; w->w_morechildren != w1; w = w->w_morechildren) continue; w->w_morechildren = 0; witness_free(w1); } static int isitmychild(struct witness *parent, struct witness *child) { struct witness *w; int i; for (w = parent; w != NULL; w = w->w_morechildren) { for (i = 0; i < w->w_childcnt; i++) { if (w->w_children[i] == child) return (1); } } return (0); } static int isitmydescendant(struct witness *parent, struct witness *child) { struct witness *w; int i; int j; for (j = 0, w = parent; w != NULL; w = w->w_morechildren, j++) { MPASS(j < 1000); for (i = 0; i < w->w_childcnt; i++) { if (w->w_children[i] == child) return (1); } for (i = 0; i < w->w_childcnt; i++) { if (isitmydescendant(w->w_children[i], child)) return (1); } } return (0); } void witness_levelall (void) { struct witness *w, *w1; for (w = w_all; w; w = w->w_next) if (!w->w_spin) w->w_level = 0; for (w = w_all; w; w = w->w_next) { if (w->w_spin) continue; for (w1 = w_all; w1; w1 = w1->w_next) { if (isitmychild(w1, w)) break; } if (w1 != NULL) continue; witness_leveldescendents(w, 0); } } static void witness_leveldescendents(struct witness *parent, int level) { int i; struct witness *w; if (parent->w_level < level) parent->w_level = level; level++; for (w = parent; w != NULL; w = w->w_morechildren) for (i = 0; i < w->w_childcnt; i++) witness_leveldescendents(w->w_children[i], level); } static void witness_displaydescendants(void(*prnt)(const char *fmt, ...), struct witness *parent) { struct witness *w; int i; int level = parent->w_level; prnt("%d", level); if (level < 10) prnt(" "); for (i = 0; i < level; i++) prnt(" "); prnt("%s", parent->w_description); if (parent->w_file != NULL) { prnt(" -- last acquired @ %s", parent->w_file); #ifndef W_USE_WHERE prnt(":%d", parent->w_line); #endif prnt("\n"); } for (w = parent; w != NULL; w = w->w_morechildren) for (i = 0; i < w->w_childcnt; i++) witness_displaydescendants(prnt, w->w_children[i]); } static int dup_ok(struct witness *w) { char **dup; for (dup = dup_list; *dup!= NULL; dup++) if (strcmp(w->w_description, *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_description, b->b_lock1) == 0) { if (strcmp(w2->w_description, b->b_lock2) == 0) return (1); continue; } if (strcmp(w1->w_description, b->b_lock2) == 0) if (strcmp(w2->w_description, b->b_lock1) == 0) return (1); } return (0); } static struct witness * witness_get() { struct witness *w; if ((w = w_free) == NULL) { witness_dead = 1; mtx_exit(&w_mtx, MTX_SPIN | MTX_QUIET); printf("witness exhausted\n"); return (NULL); } w_free = w->w_next; bzero(w, sizeof(*w)); return (w); } static void witness_free(struct witness *w) { w->w_next = w_free; w_free = w; } int witness_list(struct proc *p) { struct mtx *m; int nheld; nheld = 0; for ((m = LIST_FIRST(&p->p_heldmtx)); m != NULL; m = LIST_NEXT(m, mtx_held)) { printf("\t\"%s\" (%p) locked at %s:%d\n", m->mtx_description, m, m->mtx_witness->w_file, m->mtx_witness->w_line); nheld++; } return (nheld); } void witness_save(struct mtx *m, const char **filep, int *linep) { *filep = m->mtx_witness->w_file; *linep = m->mtx_witness->w_line; } void witness_restore(struct mtx *m, const char *file, int line) { m->mtx_witness->w_file = file; m->mtx_witness->w_line = line; } #endif /* WITNESS */