/*- * 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 $ */ /* * Machine independent bits of mutex implementation. */ #include __FBSDID("$FreeBSD$"); #include "opt_adaptive_mutexes.h" #include "opt_ddb.h" #include "opt_mutex_wake_all.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include /* * Internal utility macros. */ #define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) #define mtx_owner(m) (mtx_unowned((m)) ? NULL \ : (struct thread *)((m)->mtx_lock & MTX_FLAGMASK)) /* * Lock classes for sleep and spin mutexes. */ struct lock_class lock_class_mtx_sleep = { "sleep mutex", LC_SLEEPLOCK | LC_RECURSABLE }; struct lock_class lock_class_mtx_spin = { "spin mutex", LC_SPINLOCK | LC_RECURSABLE }; /* * System-wide mutexes */ struct mtx sched_lock; struct mtx Giant; #ifdef MUTEX_PROFILING SYSCTL_NODE(_debug, OID_AUTO, mutex, CTLFLAG_RD, NULL, "mutex debugging"); SYSCTL_NODE(_debug_mutex, OID_AUTO, prof, CTLFLAG_RD, NULL, "mutex profiling"); static int mutex_prof_enable = 0; SYSCTL_INT(_debug_mutex_prof, OID_AUTO, enable, CTLFLAG_RW, &mutex_prof_enable, 0, "Enable tracing of mutex holdtime"); struct mutex_prof { const char *name; const char *file; int line; uintmax_t cnt_max; uintmax_t cnt_tot; uintmax_t cnt_cur; uintmax_t cnt_contest_holding; uintmax_t cnt_contest_locking; struct mutex_prof *next; }; /* * mprof_buf is a static pool of profiling records to avoid possible * reentrance of the memory allocation functions. * * Note: NUM_MPROF_BUFFERS must be smaller than MPROF_HASH_SIZE. */ #define NUM_MPROF_BUFFERS 1000 static struct mutex_prof mprof_buf[NUM_MPROF_BUFFERS]; static int first_free_mprof_buf; #define MPROF_HASH_SIZE 1009 static struct mutex_prof *mprof_hash[MPROF_HASH_SIZE]; /* SWAG: sbuf size = avg stat. line size * number of locks */ #define MPROF_SBUF_SIZE 256 * 400 static int mutex_prof_acquisitions; SYSCTL_INT(_debug_mutex_prof, OID_AUTO, acquisitions, CTLFLAG_RD, &mutex_prof_acquisitions, 0, "Number of mutex acquistions recorded"); static int mutex_prof_records; SYSCTL_INT(_debug_mutex_prof, OID_AUTO, records, CTLFLAG_RD, &mutex_prof_records, 0, "Number of profiling records"); static int mutex_prof_maxrecords = NUM_MPROF_BUFFERS; SYSCTL_INT(_debug_mutex_prof, OID_AUTO, maxrecords, CTLFLAG_RD, &mutex_prof_maxrecords, 0, "Maximum number of profiling records"); static int mutex_prof_rejected; SYSCTL_INT(_debug_mutex_prof, OID_AUTO, rejected, CTLFLAG_RD, &mutex_prof_rejected, 0, "Number of rejected profiling records"); static int mutex_prof_hashsize = MPROF_HASH_SIZE; SYSCTL_INT(_debug_mutex_prof, OID_AUTO, hashsize, CTLFLAG_RD, &mutex_prof_hashsize, 0, "Hash size"); static int mutex_prof_collisions = 0; SYSCTL_INT(_debug_mutex_prof, OID_AUTO, collisions, CTLFLAG_RD, &mutex_prof_collisions, 0, "Number of hash collisions"); /* * mprof_mtx protects the profiling buffers and the hash. */ static struct mtx mprof_mtx; MTX_SYSINIT(mprof, &mprof_mtx, "mutex profiling lock", MTX_SPIN | MTX_QUIET); static u_int64_t nanoseconds(void) { struct timespec tv; nanotime(&tv); return (tv.tv_sec * (u_int64_t)1000000000 + tv.tv_nsec); } static int dump_mutex_prof_stats(SYSCTL_HANDLER_ARGS) { struct sbuf *sb; int error, i; static int multiplier = 1; if (first_free_mprof_buf == 0) return (SYSCTL_OUT(req, "No locking recorded", sizeof("No locking recorded"))); retry_sbufops: sb = sbuf_new(NULL, NULL, MPROF_SBUF_SIZE * multiplier, SBUF_FIXEDLEN); sbuf_printf(sb, "%6s %12s %11s %5s %12s %12s %s\n", "max", "total", "count", "avg", "cnt_hold", "cnt_lock", "name"); /* * XXX this spinlock seems to be by far the largest perpetrator * of spinlock latency (1.6 msec on an Athlon1600 was recorded * even before I pessimized it further by moving the average * computation here). */ mtx_lock_spin(&mprof_mtx); for (i = 0; i < first_free_mprof_buf; ++i) { sbuf_printf(sb, "%6ju %12ju %11ju %5ju %12ju %12ju %s:%d (%s)\n", mprof_buf[i].cnt_max / 1000, mprof_buf[i].cnt_tot / 1000, mprof_buf[i].cnt_cur, mprof_buf[i].cnt_cur == 0 ? (uintmax_t)0 : mprof_buf[i].cnt_tot / (mprof_buf[i].cnt_cur * 1000), mprof_buf[i].cnt_contest_holding, mprof_buf[i].cnt_contest_locking, mprof_buf[i].file, mprof_buf[i].line, mprof_buf[i].name); if (sbuf_overflowed(sb)) { mtx_unlock_spin(&mprof_mtx); sbuf_delete(sb); multiplier++; goto retry_sbufops; } } mtx_unlock_spin(&mprof_mtx); sbuf_finish(sb); error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1); sbuf_delete(sb); return (error); } SYSCTL_PROC(_debug_mutex_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD, NULL, 0, dump_mutex_prof_stats, "A", "Mutex profiling statistics"); static int reset_mutex_prof_stats(SYSCTL_HANDLER_ARGS) { int error, v; if (first_free_mprof_buf == 0) return (0); v = 0; error = sysctl_handle_int(oidp, &v, 0, req); if (error) return (error); if (req->newptr == NULL) return (error); if (v == 0) return (0); mtx_lock_spin(&mprof_mtx); bzero(mprof_buf, sizeof(*mprof_buf) * first_free_mprof_buf); bzero(mprof_hash, sizeof(struct mtx *) * MPROF_HASH_SIZE); first_free_mprof_buf = 0; mtx_unlock_spin(&mprof_mtx); return (0); } SYSCTL_PROC(_debug_mutex_prof, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW, NULL, 0, reset_mutex_prof_stats, "I", "Reset mutex profiling statistics"); #endif /* * Function versions of the inlined __mtx_* macros. These are used by * modules and can also be called from assembly language if needed. */ void _mtx_lock_flags(struct mtx *m, int opts, const char *file, int line) { MPASS(curthread != NULL); KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep, ("mtx_lock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name, file, line)); WITNESS_CHECKORDER(&m->mtx_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line); _get_sleep_lock(m, curthread, opts, file, line); LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file, line); WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); #ifdef MUTEX_PROFILING /* don't reset the timer when/if recursing */ if (m->mtx_acqtime == 0) { m->mtx_filename = file; m->mtx_lineno = line; m->mtx_acqtime = mutex_prof_enable ? nanoseconds() : 0; ++mutex_prof_acquisitions; } #endif } void _mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line) { MPASS(curthread != NULL); KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep, ("mtx_unlock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name, file, line)); WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file, line); mtx_assert(m, MA_OWNED); #ifdef MUTEX_PROFILING if (m->mtx_acqtime != 0) { static const char *unknown = "(unknown)"; struct mutex_prof *mpp; u_int64_t acqtime, now; const char *p, *q; volatile u_int hash; now = nanoseconds(); acqtime = m->mtx_acqtime; m->mtx_acqtime = 0; if (now <= acqtime) goto out; for (p = m->mtx_filename; p != NULL && strncmp(p, "../", 3) == 0; p += 3) /* nothing */ ; if (p == NULL || *p == '\0') p = unknown; for (hash = m->mtx_lineno, q = p; *q != '\0'; ++q) hash = (hash * 2 + *q) % MPROF_HASH_SIZE; mtx_lock_spin(&mprof_mtx); for (mpp = mprof_hash[hash]; mpp != NULL; mpp = mpp->next) if (mpp->line == m->mtx_lineno && strcmp(mpp->file, p) == 0) break; if (mpp == NULL) { /* Just exit if we cannot get a trace buffer */ if (first_free_mprof_buf >= NUM_MPROF_BUFFERS) { ++mutex_prof_rejected; goto unlock; } mpp = &mprof_buf[first_free_mprof_buf++]; mpp->name = mtx_name(m); mpp->file = p; mpp->line = m->mtx_lineno; mpp->next = mprof_hash[hash]; if (mprof_hash[hash] != NULL) ++mutex_prof_collisions; mprof_hash[hash] = mpp; ++mutex_prof_records; } /* * Record if the mutex has been held longer now than ever * before. */ if (now - acqtime > mpp->cnt_max) mpp->cnt_max = now - acqtime; mpp->cnt_tot += now - acqtime; mpp->cnt_cur++; /* * There's a small race, really we should cmpxchg * 0 with the current value, but that would bill * the contention to the wrong lock instance if * it followed this also. */ mpp->cnt_contest_holding += m->mtx_contest_holding; m->mtx_contest_holding = 0; mpp->cnt_contest_locking += m->mtx_contest_locking; m->mtx_contest_locking = 0; unlock: mtx_unlock_spin(&mprof_mtx); } out: #endif _rel_sleep_lock(m, curthread, opts, file, line); } void _mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line) { MPASS(curthread != NULL); KASSERT(m->mtx_object.lo_class == &lock_class_mtx_spin, ("mtx_lock_spin() of sleep mutex %s @ %s:%d", m->mtx_object.lo_name, file, line)); WITNESS_CHECKORDER(&m->mtx_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line); #if defined(SMP) || LOCK_DEBUG > 0 || 1 _get_spin_lock(m, curthread, opts, file, line); #else critical_enter(); #endif LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file, line); WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); } void _mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line) { MPASS(curthread != NULL); KASSERT(m->mtx_object.lo_class == &lock_class_mtx_spin, ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", m->mtx_object.lo_name, file, line)); WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file, line); mtx_assert(m, MA_OWNED); #if defined(SMP) || LOCK_DEBUG > 0 || 1 _rel_spin_lock(m); #else critical_exit(); #endif } /* * The important part of mtx_trylock{,_flags}() * Tries to acquire lock `m.' If this function is called on a mutex that * is already owned, it will recursively acquire the lock. */ int _mtx_trylock(struct mtx *m, int opts, const char *file, int line) { int rval; MPASS(curthread != NULL); if (mtx_owned(m) && (m->mtx_object.lo_flags & LO_RECURSABLE) != 0) { m->mtx_recurse++; atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); rval = 1; } else rval = _obtain_lock(m, curthread); LOCK_LOG_TRY("LOCK", &m->mtx_object, opts, rval, file, line); if (rval) WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, file, line); return (rval); } /* * _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock. * * We call this if the lock is either contested (i.e. we need to go to * sleep waiting for it), or if we need to recurse on it. */ void _mtx_lock_sleep(struct mtx *m, int opts, const char *file, int line) { struct turnstile *ts; struct thread *td = curthread; #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) struct thread *owner; #endif uintptr_t v; #ifdef KTR int cont_logged = 0; #endif #ifdef MUTEX_PROFILING int contested; #endif if (mtx_owned(m)) { KASSERT((m->mtx_object.lo_flags & LO_RECURSABLE) != 0, ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", m->mtx_object.lo_name, file, line)); m->mtx_recurse++; atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); if (LOCK_LOG_TEST(&m->mtx_object, opts)) CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); return; } if (LOCK_LOG_TEST(&m->mtx_object, opts)) CTR4(KTR_LOCK, "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", m->mtx_object.lo_name, (void *)m->mtx_lock, file, line); #ifdef MUTEX_PROFILING contested = 0; #endif while (!_obtain_lock(m, td)) { #ifdef MUTEX_PROFILING contested = 1; atomic_add_int(&m->mtx_contest_holding, 1); #endif ts = turnstile_lookup(&m->mtx_object); v = m->mtx_lock; /* * Check if the lock has been released while spinning for * the turnstile chain lock. */ if (v == MTX_UNOWNED) { turnstile_release(&m->mtx_object); #if defined(__i386__) || defined(__amd64__) ia32_pause(); #endif continue; } #ifdef MUTEX_WAKE_ALL MPASS(v != MTX_CONTESTED); #else /* * The mutex was marked contested on release. This means that * there are other threads blocked on it. Grab ownership of * it and propagate its priority to the current thread if * necessary. */ if (v == MTX_CONTESTED) { MPASS(ts != NULL); m->mtx_lock = (uintptr_t)td | MTX_CONTESTED; turnstile_claim(ts); break; } #endif /* * If the mutex isn't already contested and a failure occurs * setting the contested bit, the mutex was either released * or the state of the MTX_RECURSED bit changed. */ if ((v & MTX_CONTESTED) == 0 && !atomic_cmpset_ptr(&m->mtx_lock, (void *)v, (void *)(v | MTX_CONTESTED))) { turnstile_release(&m->mtx_object); #if defined(__i386__) || defined(__amd64__) ia32_pause(); #endif continue; } #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) /* * If the current owner of the lock is executing on another * CPU, spin instead of blocking. */ owner = (struct thread *)(v & MTX_FLAGMASK); if (m != &Giant && TD_IS_RUNNING(owner)) { turnstile_release(&m->mtx_object); while (mtx_owner(m) == owner && TD_IS_RUNNING(owner)) { #if defined(__i386__) || defined(__amd64__) ia32_pause(); #endif } continue; } #endif /* SMP && !NO_ADAPTIVE_MUTEXES */ /* * We definitely must sleep for this lock. */ mtx_assert(m, MA_NOTOWNED); #ifdef KTR if (!cont_logged) { CTR6(KTR_CONTENTION, "contention: %p at %s:%d wants %s, taken by %s:%d", td, file, line, m->mtx_object.lo_name, WITNESS_FILE(&m->mtx_object), WITNESS_LINE(&m->mtx_object)); cont_logged = 1; } #endif /* * Block on the turnstile. */ turnstile_wait(ts, &m->mtx_object, mtx_owner(m)); } #ifdef KTR if (cont_logged) { CTR4(KTR_CONTENTION, "contention end: %s acquired by %p at %s:%d", m->mtx_object.lo_name, td, file, line); } #endif #ifdef MUTEX_PROFILING if (contested) m->mtx_contest_locking++; m->mtx_contest_holding = 0; #endif return; } /* * _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock. * * This is only called if we need to actually spin for the lock. Recursion * is handled inline. */ void _mtx_lock_spin(struct mtx *m, int opts, const char *file, int line) { int i = 0; if (LOCK_LOG_TEST(&m->mtx_object, opts)) CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); for (;;) { if (_obtain_lock(m, curthread)) break; /* Give interrupts a chance while we spin. */ critical_exit(); while (m->mtx_lock != MTX_UNOWNED) { if (i++ < 10000000) { #if defined(__i386__) || defined(__amd64__) ia32_pause(); #endif continue; } if (i < 60000000) DELAY(1); else if (!kdb_active) { printf("spin lock %s held by %p for > 5 seconds\n", m->mtx_object.lo_name, (void *)m->mtx_lock); #ifdef WITNESS witness_display_spinlock(&m->mtx_object, mtx_owner(m)); #endif panic("spin lock held too long"); } #if defined(__i386__) || defined(__amd64__) ia32_pause(); #endif } critical_enter(); } if (LOCK_LOG_TEST(&m->mtx_object, opts)) CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); return; } /* * _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock. * * We are only called here if the lock is recursed or contested (i.e. we * need to wake up a blocked thread). */ void _mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line) { struct turnstile *ts; #ifndef PREEMPTION struct thread *td, *td1; #endif if (mtx_recursed(m)) { if (--(m->mtx_recurse) == 0) atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); if (LOCK_LOG_TEST(&m->mtx_object, opts)) CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); return; } ts = turnstile_lookup(&m->mtx_object); if (LOCK_LOG_TEST(&m->mtx_object, opts)) CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); #if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) if (ts == NULL) { _release_lock_quick(m); if (LOCK_LOG_TEST(&m->mtx_object, opts)) CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m); turnstile_release(&m->mtx_object); return; } #else MPASS(ts != NULL); #endif #ifndef PREEMPTION /* XXX */ td1 = turnstile_head(ts); #endif #ifdef MUTEX_WAKE_ALL turnstile_broadcast(ts); _release_lock_quick(m); #else if (turnstile_signal(ts)) { _release_lock_quick(m); if (LOCK_LOG_TEST(&m->mtx_object, opts)) CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m); } else { m->mtx_lock = MTX_CONTESTED; if (LOCK_LOG_TEST(&m->mtx_object, opts)) CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p still contested", m); } #endif turnstile_unpend(ts); #ifndef PREEMPTION /* * XXX: This is just a hack until preemption is done. However, * once preemption is done we need to either wrap the * turnstile_signal() and release of the actual lock in an * extra critical section or change the preemption code to * always just set a flag and never do instant-preempts. */ td = curthread; if (td->td_critnest > 0 || td1->td_priority >= td->td_priority) return; mtx_lock_spin(&sched_lock); if (!TD_IS_RUNNING(td1)) { #ifdef notyet if (td->td_ithd != NULL) { struct ithd *it = td->td_ithd; if (it->it_interrupted) { if (LOCK_LOG_TEST(&m->mtx_object, opts)) CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p interrupted %p", it, it->it_interrupted); intr_thd_fixup(it); } } #endif if (LOCK_LOG_TEST(&m->mtx_object, opts)) CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p switching out lock=%p", m, (void *)m->mtx_lock); mi_switch(SW_INVOL, NULL); if (LOCK_LOG_TEST(&m->mtx_object, opts)) CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p", m, (void *)m->mtx_lock); } mtx_unlock_spin(&sched_lock); #endif return; } /* * All the unlocking of MTX_SPIN locks is done inline. * See the _rel_spin_lock() macro for the details. */ /* * The backing function for the INVARIANTS-enabled mtx_assert() */ #ifdef INVARIANT_SUPPORT void _mtx_assert(struct mtx *m, int what, const char *file, int line) { if (panicstr != NULL) return; switch (what) { case MA_OWNED: case MA_OWNED | MA_RECURSED: case MA_OWNED | MA_NOTRECURSED: if (!mtx_owned(m)) panic("mutex %s not owned at %s:%d", m->mtx_object.lo_name, file, line); if (mtx_recursed(m)) { if ((what & MA_NOTRECURSED) != 0) panic("mutex %s recursed at %s:%d", m->mtx_object.lo_name, file, line); } else if ((what & MA_RECURSED) != 0) { panic("mutex %s unrecursed at %s:%d", m->mtx_object.lo_name, file, line); } break; case MA_NOTOWNED: if (mtx_owned(m)) panic("mutex %s owned at %s:%d", m->mtx_object.lo_name, file, line); break; default: panic("unknown mtx_assert at %s:%d", file, line); } } #endif /* * The MUTEX_DEBUG-enabled mtx_validate() * * Most of these checks have been moved off into the LO_INITIALIZED flag * maintained by the witness code. */ #ifdef MUTEX_DEBUG void mtx_validate(struct mtx *); void mtx_validate(struct mtx *m) { /* * XXX: When kernacc() does not require Giant we can reenable this check */ #ifdef notyet /* * XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly * we can re-enable the kernacc() checks. */ #ifndef __alpha__ /* * Can't call kernacc() from early init386(), especially when * initializing Giant mutex, because some stuff in kernacc() * requires Giant itself. */ if (!cold) if (!kernacc((caddr_t)m, sizeof(m), VM_PROT_READ | VM_PROT_WRITE)) panic("Can't read and write to mutex %p", m); #endif #endif } #endif /* * General init routine used by the MTX_SYSINIT() macro. */ void mtx_sysinit(void *arg) { struct mtx_args *margs = arg; mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts); } /* * Mutex initialization routine; initialize lock `m' of type contained in * `opts' with options contained in `opts' and name `name.' The optional * lock type `type' is used as a general lock category name for use with * witness. */ void mtx_init(struct mtx *m, const char *name, const char *type, int opts) { struct lock_object *lock; MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | MTX_NOWITNESS | MTX_DUPOK)) == 0); #ifdef MUTEX_DEBUG /* Diagnostic and error correction */ mtx_validate(m); #endif lock = &m->mtx_object; KASSERT((lock->lo_flags & LO_INITIALIZED) == 0, ("mutex \"%s\" %p already initialized", name, m)); bzero(m, sizeof(*m)); if (opts & MTX_SPIN) lock->lo_class = &lock_class_mtx_spin; else lock->lo_class = &lock_class_mtx_sleep; lock->lo_name = name; lock->lo_type = type != NULL ? type : name; if (opts & MTX_QUIET) lock->lo_flags = LO_QUIET; if (opts & MTX_RECURSE) lock->lo_flags |= LO_RECURSABLE; if ((opts & MTX_NOWITNESS) == 0) lock->lo_flags |= LO_WITNESS; if (opts & MTX_DUPOK) lock->lo_flags |= LO_DUPOK; m->mtx_lock = MTX_UNOWNED; LOCK_LOG_INIT(lock, opts); WITNESS_INIT(lock); } /* * Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be * passed in as a flag here because if the corresponding mtx_init() was * called with MTX_QUIET set, then it will already be set in the mutex's * flags. */ void mtx_destroy(struct mtx *m) { LOCK_LOG_DESTROY(&m->mtx_object, 0); if (!mtx_owned(m)) MPASS(mtx_unowned(m)); else { MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); /* Tell witness this isn't locked to make it happy. */ WITNESS_UNLOCK(&m->mtx_object, LOP_EXCLUSIVE, __FILE__, __LINE__); } WITNESS_DESTROY(&m->mtx_object); } /* * Intialize the mutex code and system mutexes. This is called from the MD * startup code prior to mi_startup(). The per-CPU data space needs to be * setup before this is called. */ void mutex_init(void) { /* Setup thread0 so that mutexes work. */ LIST_INIT(&thread0.td_contested); /* Setup turnstiles so that sleep mutexes work. */ init_turnstiles(); /* * Initialize mutexes. */ mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE); mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); mtx_lock(&Giant); }