diff options
Diffstat (limited to 'sys/kern/kern_mutex.c')
| -rw-r--r-- | sys/kern/kern_mutex.c | 1009 |
1 files changed, 1009 insertions, 0 deletions
diff --git a/sys/kern/kern_mutex.c b/sys/kern/kern_mutex.c new file mode 100644 index 0000000..cd1ed7d --- /dev/null +++ b/sys/kern/kern_mutex.c @@ -0,0 +1,1009 @@ +/*- + * 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 <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "opt_adaptive_mutexes.h" +#include "opt_ddb.h" +#include "opt_global.h" +#include "opt_hwpmc_hooks.h" +#include "opt_kdtrace.h" +#include "opt_sched.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/bus.h> +#include <sys/conf.h> +#include <sys/kdb.h> +#include <sys/kernel.h> +#include <sys/ktr.h> +#include <sys/lock.h> +#include <sys/malloc.h> +#include <sys/mutex.h> +#include <sys/proc.h> +#include <sys/resourcevar.h> +#include <sys/sched.h> +#include <sys/sbuf.h> +#include <sys/sysctl.h> +#include <sys/turnstile.h> +#include <sys/vmmeter.h> +#include <sys/lock_profile.h> + +#include <machine/atomic.h> +#include <machine/bus.h> +#include <machine/cpu.h> + +#include <ddb/ddb.h> + +#include <fs/devfs/devfs_int.h> + +#include <vm/vm.h> +#include <vm/vm_extern.h> + +#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES) +#define ADAPTIVE_MUTEXES +#endif + +#ifdef HWPMC_HOOKS +#include <sys/pmckern.h> +PMC_SOFT_DEFINE( , , lock, failed); +#endif + +/* + * Return the mutex address when the lock cookie address is provided. + * This functionality assumes that struct mtx* have a member named mtx_lock. + */ +#define mtxlock2mtx(c) (__containerof(c, struct mtx, mtx_lock)) + +/* + * Internal utility macros. + */ +#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED) + +#define mtx_destroyed(m) ((m)->mtx_lock == MTX_DESTROYED) + +#define mtx_owner(m) ((struct thread *)((m)->mtx_lock & ~MTX_FLAGMASK)) + +static void assert_mtx(const struct lock_object *lock, int what); +#ifdef DDB +static void db_show_mtx(const struct lock_object *lock); +#endif +static void lock_mtx(struct lock_object *lock, int how); +static void lock_spin(struct lock_object *lock, int how); +#ifdef KDTRACE_HOOKS +static int owner_mtx(const struct lock_object *lock, + struct thread **owner); +#endif +static int unlock_mtx(struct lock_object *lock); +static int unlock_spin(struct lock_object *lock); + +/* + * Lock classes for sleep and spin mutexes. + */ +struct lock_class lock_class_mtx_sleep = { + .lc_name = "sleep mutex", + .lc_flags = LC_SLEEPLOCK | LC_RECURSABLE, + .lc_assert = assert_mtx, +#ifdef DDB + .lc_ddb_show = db_show_mtx, +#endif + .lc_lock = lock_mtx, + .lc_unlock = unlock_mtx, +#ifdef KDTRACE_HOOKS + .lc_owner = owner_mtx, +#endif +}; +struct lock_class lock_class_mtx_spin = { + .lc_name = "spin mutex", + .lc_flags = LC_SPINLOCK | LC_RECURSABLE, + .lc_assert = assert_mtx, +#ifdef DDB + .lc_ddb_show = db_show_mtx, +#endif + .lc_lock = lock_spin, + .lc_unlock = unlock_spin, +#ifdef KDTRACE_HOOKS + .lc_owner = owner_mtx, +#endif +}; + +/* + * System-wide mutexes + */ +struct mtx blocked_lock; +struct mtx Giant; + +void +assert_mtx(const struct lock_object *lock, int what) +{ + + mtx_assert((const struct mtx *)lock, what); +} + +void +lock_mtx(struct lock_object *lock, int how) +{ + + mtx_lock((struct mtx *)lock); +} + +void +lock_spin(struct lock_object *lock, int how) +{ + + panic("spin locks can only use msleep_spin"); +} + +int +unlock_mtx(struct lock_object *lock) +{ + struct mtx *m; + + m = (struct mtx *)lock; + mtx_assert(m, MA_OWNED | MA_NOTRECURSED); + mtx_unlock(m); + return (0); +} + +int +unlock_spin(struct lock_object *lock) +{ + + panic("spin locks can only use msleep_spin"); +} + +#ifdef KDTRACE_HOOKS +int +owner_mtx(const struct lock_object *lock, struct thread **owner) +{ + const struct mtx *m = (const struct mtx *)lock; + + *owner = mtx_owner(m); + return (mtx_unowned(m) == 0); +} +#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(volatile uintptr_t *c, int opts, const char *file, int line) +{ + struct mtx *m; + + if (SCHEDULER_STOPPED()) + return; + + m = mtxlock2mtx(c); + + KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), + ("mtx_lock() by idle thread %p on sleep mutex %s @ %s:%d", + curthread, m->lock_object.lo_name, file, line)); + KASSERT(m->mtx_lock != MTX_DESTROYED, + ("mtx_lock() of destroyed mutex @ %s:%d", file, line)); + KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, + ("mtx_lock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, + file, line)); + WITNESS_CHECKORDER(&m->lock_object, (opts & ~MTX_RECURSE) | + LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); + + __mtx_lock(m, curthread, opts, file, line); + LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, + line); + WITNESS_LOCK(&m->lock_object, (opts & ~MTX_RECURSE) | LOP_EXCLUSIVE, + file, line); + curthread->td_locks++; +} + +void +__mtx_unlock_flags(volatile uintptr_t *c, int opts, const char *file, int line) +{ + struct mtx *m; + + if (SCHEDULER_STOPPED()) + return; + + m = mtxlock2mtx(c); + + KASSERT(m->mtx_lock != MTX_DESTROYED, + ("mtx_unlock() of destroyed mutex @ %s:%d", file, line)); + KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, + ("mtx_unlock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, + file, line)); + WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); + LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, + line); + mtx_assert(m, MA_OWNED); + + if (m->mtx_recurse == 0) + LOCKSTAT_PROFILE_RELEASE_LOCK(LS_MTX_UNLOCK_RELEASE, m); + __mtx_unlock(m, curthread, opts, file, line); + curthread->td_locks--; +} + +void +__mtx_lock_spin_flags(volatile uintptr_t *c, int opts, const char *file, + int line) +{ + struct mtx *m; + + if (SCHEDULER_STOPPED()) + return; + + m = mtxlock2mtx(c); + + KASSERT(m->mtx_lock != MTX_DESTROYED, + ("mtx_lock_spin() of destroyed mutex @ %s:%d", file, line)); + KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, + ("mtx_lock_spin() of sleep mutex %s @ %s:%d", + m->lock_object.lo_name, file, line)); + if (mtx_owned(m)) + KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || + (opts & MTX_RECURSE) != 0, + ("mtx_lock_spin: recursed on non-recursive mutex %s @ %s:%d\n", + m->lock_object.lo_name, file, line)); + opts &= ~MTX_RECURSE; + WITNESS_CHECKORDER(&m->lock_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE, + file, line, NULL); + __mtx_lock_spin(m, curthread, opts, file, line); + LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, + line); + WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); +} + +void +__mtx_unlock_spin_flags(volatile uintptr_t *c, int opts, const char *file, + int line) +{ + struct mtx *m; + + if (SCHEDULER_STOPPED()) + return; + + m = mtxlock2mtx(c); + + KASSERT(m->mtx_lock != MTX_DESTROYED, + ("mtx_unlock_spin() of destroyed mutex @ %s:%d", file, line)); + KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, + ("mtx_unlock_spin() of sleep mutex %s @ %s:%d", + m->lock_object.lo_name, file, line)); + WITNESS_UNLOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); + LOCK_LOG_LOCK("UNLOCK", &m->lock_object, opts, m->mtx_recurse, file, + line); + mtx_assert(m, MA_OWNED); + + __mtx_unlock_spin(m); +} + +/* + * 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_flags_(volatile uintptr_t *c, int opts, const char *file, int line) +{ + struct mtx *m; +#ifdef LOCK_PROFILING + uint64_t waittime = 0; + int contested = 0; +#endif + int rval; + + if (SCHEDULER_STOPPED()) + return (1); + + m = mtxlock2mtx(c); + + KASSERT(kdb_active != 0 || !TD_IS_IDLETHREAD(curthread), + ("mtx_trylock() by idle thread %p on sleep mutex %s @ %s:%d", + curthread, m->lock_object.lo_name, file, line)); + KASSERT(m->mtx_lock != MTX_DESTROYED, + ("mtx_trylock() of destroyed mutex @ %s:%d", file, line)); + KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_sleep, + ("mtx_trylock() of spin mutex %s @ %s:%d", m->lock_object.lo_name, + file, line)); + + if (mtx_owned(m) && ((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || + (opts & MTX_RECURSE) != 0)) { + m->mtx_recurse++; + atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); + rval = 1; + } else + rval = _mtx_obtain_lock(m, (uintptr_t)curthread); + opts &= ~MTX_RECURSE; + + LOCK_LOG_TRY("LOCK", &m->lock_object, opts, rval, file, line); + if (rval) { + WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK, + file, line); + curthread->td_locks++; + if (m->mtx_recurse == 0) + LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, + m, contested, waittime, 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(volatile uintptr_t *c, uintptr_t tid, int opts, + const char *file, int line) +{ + struct mtx *m; + struct turnstile *ts; + uintptr_t v; +#ifdef ADAPTIVE_MUTEXES + volatile struct thread *owner; +#endif +#ifdef KTR + int cont_logged = 0; +#endif +#ifdef LOCK_PROFILING + int contested = 0; + uint64_t waittime = 0; +#endif +#ifdef KDTRACE_HOOKS + uint64_t spin_cnt = 0; + uint64_t sleep_cnt = 0; + int64_t sleep_time = 0; +#endif + + if (SCHEDULER_STOPPED()) + return; + + m = mtxlock2mtx(c); + + if (mtx_owned(m)) { + KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0 || + (opts & MTX_RECURSE) != 0, + ("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n", + m->lock_object.lo_name, file, line)); + opts &= ~MTX_RECURSE; + m->mtx_recurse++; + atomic_set_ptr(&m->mtx_lock, MTX_RECURSED); + if (LOCK_LOG_TEST(&m->lock_object, opts)) + CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m); + return; + } + opts &= ~MTX_RECURSE; + +#ifdef HWPMC_HOOKS + PMC_SOFT_CALL( , , lock, failed); +#endif + lock_profile_obtain_lock_failed(&m->lock_object, + &contested, &waittime); + if (LOCK_LOG_TEST(&m->lock_object, opts)) + CTR4(KTR_LOCK, + "_mtx_lock_sleep: %s contested (lock=%p) at %s:%d", + m->lock_object.lo_name, (void *)m->mtx_lock, file, line); + + while (!_mtx_obtain_lock(m, tid)) { +#ifdef KDTRACE_HOOKS + spin_cnt++; +#endif +#ifdef ADAPTIVE_MUTEXES + /* + * If the owner is running on another CPU, spin until the + * owner stops running or the state of the lock changes. + */ + v = m->mtx_lock; + if (v != MTX_UNOWNED) { + owner = (struct thread *)(v & ~MTX_FLAGMASK); + if (TD_IS_RUNNING(owner)) { + if (LOCK_LOG_TEST(&m->lock_object, 0)) + CTR3(KTR_LOCK, + "%s: spinning on %p held by %p", + __func__, m, owner); + while (mtx_owner(m) == owner && + TD_IS_RUNNING(owner)) { + cpu_spinwait(); +#ifdef KDTRACE_HOOKS + spin_cnt++; +#endif + } + continue; + } + } +#endif + + ts = turnstile_trywait(&m->lock_object); + v = m->mtx_lock; + + /* + * Check if the lock has been released while spinning for + * the turnstile chain lock. + */ + if (v == MTX_UNOWNED) { + turnstile_cancel(ts); + continue; + } + +#ifdef ADAPTIVE_MUTEXES + /* + * The current lock owner might have started executing + * on another CPU (or the lock could have changed + * owners) while we were waiting on the turnstile + * chain lock. If so, drop the turnstile lock and try + * again. + */ + owner = (struct thread *)(v & ~MTX_FLAGMASK); + if (TD_IS_RUNNING(owner)) { + turnstile_cancel(ts); + continue; + } +#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, v, v | MTX_CONTESTED)) { + turnstile_cancel(ts); + continue; + } + + /* + * 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", + (void *)tid, file, line, m->lock_object.lo_name, + WITNESS_FILE(&m->lock_object), + WITNESS_LINE(&m->lock_object)); + cont_logged = 1; + } +#endif + + /* + * Block on the turnstile. + */ +#ifdef KDTRACE_HOOKS + sleep_time -= lockstat_nsecs(); +#endif + turnstile_wait(ts, mtx_owner(m), TS_EXCLUSIVE_QUEUE); +#ifdef KDTRACE_HOOKS + sleep_time += lockstat_nsecs(); + sleep_cnt++; +#endif + } +#ifdef KTR + if (cont_logged) { + CTR4(KTR_CONTENTION, + "contention end: %s acquired by %p at %s:%d", + m->lock_object.lo_name, (void *)tid, file, line); + } +#endif + LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_LOCK_ACQUIRE, m, contested, + waittime, file, line); +#ifdef KDTRACE_HOOKS + if (sleep_time) + LOCKSTAT_RECORD1(LS_MTX_LOCK_BLOCK, m, sleep_time); + + /* + * Only record the loops spinning and not sleeping. + */ + if (spin_cnt > sleep_cnt) + LOCKSTAT_RECORD1(LS_MTX_LOCK_SPIN, m, (spin_cnt - sleep_cnt)); +#endif +} + +static void +_mtx_lock_spin_failed(struct mtx *m) +{ + struct thread *td; + + td = mtx_owner(m); + + /* If the mutex is unlocked, try again. */ + if (td == NULL) + return; + + printf( "spin lock %p (%s) held by %p (tid %d) too long\n", + m, m->lock_object.lo_name, td, td->td_tid); +#ifdef WITNESS + witness_display_spinlock(&m->lock_object, td, printf); +#endif + panic("spin lock held too long"); +} + +#ifdef SMP +/* + * _mtx_lock_spin_cookie: 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_cookie(volatile uintptr_t *c, uintptr_t tid, int opts, + const char *file, int line) +{ + struct mtx *m; + int i = 0; +#ifdef LOCK_PROFILING + int contested = 0; + uint64_t waittime = 0; +#endif + + if (SCHEDULER_STOPPED()) + return; + + m = mtxlock2mtx(c); + + if (LOCK_LOG_TEST(&m->lock_object, opts)) + CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m); + +#ifdef HWPMC_HOOKS + PMC_SOFT_CALL( , , lock, failed); +#endif + lock_profile_obtain_lock_failed(&m->lock_object, &contested, &waittime); + while (!_mtx_obtain_lock(m, tid)) { + + /* Give interrupts a chance while we spin. */ + spinlock_exit(); + while (m->mtx_lock != MTX_UNOWNED) { + if (i++ < 10000000) { + cpu_spinwait(); + continue; + } + if (i < 60000000 || kdb_active || panicstr != NULL) + DELAY(1); + else + _mtx_lock_spin_failed(m); + cpu_spinwait(); + } + spinlock_enter(); + } + + if (LOCK_LOG_TEST(&m->lock_object, opts)) + CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m); + + LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, m, + contested, waittime, (file), (line)); + LOCKSTAT_RECORD1(LS_MTX_SPIN_LOCK_SPIN, m, i); +} +#endif /* SMP */ + +void +thread_lock_flags_(struct thread *td, int opts, const char *file, int line) +{ + struct mtx *m; + uintptr_t tid; + int i; +#ifdef LOCK_PROFILING + int contested = 0; + uint64_t waittime = 0; +#endif +#ifdef KDTRACE_HOOKS + uint64_t spin_cnt = 0; +#endif + + i = 0; + tid = (uintptr_t)curthread; + + if (SCHEDULER_STOPPED()) + return; + + for (;;) { +retry: + spinlock_enter(); + m = td->td_lock; + KASSERT(m->mtx_lock != MTX_DESTROYED, + ("thread_lock() of destroyed mutex @ %s:%d", file, line)); + KASSERT(LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin, + ("thread_lock() of sleep mutex %s @ %s:%d", + m->lock_object.lo_name, file, line)); + if (mtx_owned(m)) + KASSERT((m->lock_object.lo_flags & LO_RECURSABLE) != 0, + ("thread_lock: recursed on non-recursive mutex %s @ %s:%d\n", + m->lock_object.lo_name, file, line)); + WITNESS_CHECKORDER(&m->lock_object, + opts | LOP_NEWORDER | LOP_EXCLUSIVE, file, line, NULL); + while (!_mtx_obtain_lock(m, tid)) { +#ifdef KDTRACE_HOOKS + spin_cnt++; +#endif + if (m->mtx_lock == tid) { + m->mtx_recurse++; + break; + } +#ifdef HWPMC_HOOKS + PMC_SOFT_CALL( , , lock, failed); +#endif + lock_profile_obtain_lock_failed(&m->lock_object, + &contested, &waittime); + /* Give interrupts a chance while we spin. */ + spinlock_exit(); + while (m->mtx_lock != MTX_UNOWNED) { + if (i++ < 10000000) + cpu_spinwait(); + else if (i < 60000000 || + kdb_active || panicstr != NULL) + DELAY(1); + else + _mtx_lock_spin_failed(m); + cpu_spinwait(); + if (m != td->td_lock) + goto retry; + } + spinlock_enter(); + } + if (m == td->td_lock) + break; + __mtx_unlock_spin(m); /* does spinlock_exit() */ +#ifdef KDTRACE_HOOKS + spin_cnt++; +#endif + } + if (m->mtx_recurse == 0) + LOCKSTAT_PROFILE_OBTAIN_LOCK_SUCCESS(LS_MTX_SPIN_LOCK_ACQUIRE, + m, contested, waittime, (file), (line)); + LOCK_LOG_LOCK("LOCK", &m->lock_object, opts, m->mtx_recurse, file, + line); + WITNESS_LOCK(&m->lock_object, opts | LOP_EXCLUSIVE, file, line); + LOCKSTAT_RECORD1(LS_THREAD_LOCK_SPIN, m, spin_cnt); +} + +struct mtx * +thread_lock_block(struct thread *td) +{ + struct mtx *lock; + + THREAD_LOCK_ASSERT(td, MA_OWNED); + lock = td->td_lock; + td->td_lock = &blocked_lock; + mtx_unlock_spin(lock); + + return (lock); +} + +void +thread_lock_unblock(struct thread *td, struct mtx *new) +{ + mtx_assert(new, MA_OWNED); + MPASS(td->td_lock == &blocked_lock); + atomic_store_rel_ptr((volatile void *)&td->td_lock, (uintptr_t)new); +} + +void +thread_lock_set(struct thread *td, struct mtx *new) +{ + struct mtx *lock; + + mtx_assert(new, MA_OWNED); + THREAD_LOCK_ASSERT(td, MA_OWNED); + lock = td->td_lock; + td->td_lock = new; + mtx_unlock_spin(lock); +} + +/* + * __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(volatile uintptr_t *c, int opts, const char *file, int line) +{ + struct mtx *m; + struct turnstile *ts; + + if (SCHEDULER_STOPPED()) + return; + + m = mtxlock2mtx(c); + + if (mtx_recursed(m)) { + if (--(m->mtx_recurse) == 0) + atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED); + if (LOCK_LOG_TEST(&m->lock_object, opts)) + CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m); + return; + } + + /* + * We have to lock the chain before the turnstile so this turnstile + * can be removed from the hash list if it is empty. + */ + turnstile_chain_lock(&m->lock_object); + ts = turnstile_lookup(&m->lock_object); + if (LOCK_LOG_TEST(&m->lock_object, opts)) + CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); + MPASS(ts != NULL); + turnstile_broadcast(ts, TS_EXCLUSIVE_QUEUE); + _mtx_release_lock_quick(m); + + /* + * This turnstile is now no longer associated with the mutex. We can + * unlock the chain lock so a new turnstile may take it's place. + */ + turnstile_unpend(ts, TS_EXCLUSIVE_LOCK); + turnstile_chain_unlock(&m->lock_object); +} + +/* + * All the unlocking of MTX_SPIN locks is done inline. + * See the __mtx_unlock_spin() macro for the details. + */ + +/* + * The backing function for the INVARIANTS-enabled mtx_assert() + */ +#ifdef INVARIANT_SUPPORT +void +__mtx_assert(const volatile uintptr_t *c, int what, const char *file, int line) +{ + const struct mtx *m; + + if (panicstr != NULL || dumping) + return; + + m = mtxlock2mtx(c); + + 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->lock_object.lo_name, file, line); + if (mtx_recursed(m)) { + if ((what & MA_NOTRECURSED) != 0) + panic("mutex %s recursed at %s:%d", + m->lock_object.lo_name, file, line); + } else if ((what & MA_RECURSED) != 0) { + panic("mutex %s unrecursed at %s:%d", + m->lock_object.lo_name, file, line); + } + break; + case MA_NOTOWNED: + if (mtx_owned(m)) + panic("mutex %s owned at %s:%d", + m->lock_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 + /* + * 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 + +/* + * General init routine used by the MTX_SYSINIT() macro. + */ +void +mtx_sysinit(void *arg) +{ + struct mtx_args *margs = arg; + + mtx_init((struct mtx *)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(volatile uintptr_t *c, const char *name, const char *type, int opts) +{ + struct mtx *m; + struct lock_class *class; + int flags; + + m = mtxlock2mtx(c); + + MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE | + MTX_NOWITNESS | MTX_DUPOK | MTX_NOPROFILE)) == 0); + ASSERT_ATOMIC_LOAD_PTR(m->mtx_lock, + ("%s: mtx_lock not aligned for %s: %p", __func__, name, + &m->mtx_lock)); + +#ifdef MUTEX_DEBUG + /* Diagnostic and error correction */ + mtx_validate(m); +#endif + + /* Determine lock class and lock flags. */ + if (opts & MTX_SPIN) + class = &lock_class_mtx_spin; + else + class = &lock_class_mtx_sleep; + flags = 0; + if (opts & MTX_QUIET) + flags |= LO_QUIET; + if (opts & MTX_RECURSE) + flags |= LO_RECURSABLE; + if ((opts & MTX_NOWITNESS) == 0) + flags |= LO_WITNESS; + if (opts & MTX_DUPOK) + flags |= LO_DUPOK; + if (opts & MTX_NOPROFILE) + flags |= LO_NOPROFILE; + + /* Initialize mutex. */ + lock_init(&m->lock_object, class, name, type, flags); + + m->mtx_lock = MTX_UNOWNED; + m->mtx_recurse = 0; +} + +/* + * 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(volatile uintptr_t *c) +{ + struct mtx *m; + + m = mtxlock2mtx(c); + + if (!mtx_owned(m)) + MPASS(mtx_unowned(m)); + else { + MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0); + + /* Perform the non-mtx related part of mtx_unlock_spin(). */ + if (LOCK_CLASS(&m->lock_object) == &lock_class_mtx_spin) + spinlock_exit(); + else + curthread->td_locks--; + + lock_profile_release_lock(&m->lock_object); + /* Tell witness this isn't locked to make it happy. */ + WITNESS_UNLOCK(&m->lock_object, LOP_EXCLUSIVE, __FILE__, + __LINE__); + } + + m->mtx_lock = MTX_DESTROYED; + lock_destroy(&m->lock_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 turnstiles so that sleep mutexes work. */ + init_turnstiles(); + + /* + * Initialize mutexes. + */ + mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE); + mtx_init(&blocked_lock, "blocked lock", NULL, MTX_SPIN); + blocked_lock.mtx_lock = 0xdeadc0de; /* Always blocked. */ + mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK); + mtx_init(&proc0.p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE); + mtx_init(&devmtx, "cdev", NULL, MTX_DEF); + mtx_lock(&Giant); +} + +#ifdef DDB +void +db_show_mtx(const struct lock_object *lock) +{ + struct thread *td; + const struct mtx *m; + + m = (const struct mtx *)lock; + + db_printf(" flags: {"); + if (LOCK_CLASS(lock) == &lock_class_mtx_spin) + db_printf("SPIN"); + else + db_printf("DEF"); + if (m->lock_object.lo_flags & LO_RECURSABLE) + db_printf(", RECURSE"); + if (m->lock_object.lo_flags & LO_DUPOK) + db_printf(", DUPOK"); + db_printf("}\n"); + db_printf(" state: {"); + if (mtx_unowned(m)) + db_printf("UNOWNED"); + else if (mtx_destroyed(m)) + db_printf("DESTROYED"); + else { + db_printf("OWNED"); + if (m->mtx_lock & MTX_CONTESTED) + db_printf(", CONTESTED"); + if (m->mtx_lock & MTX_RECURSED) + db_printf(", RECURSED"); + } + db_printf("}\n"); + if (!mtx_unowned(m) && !mtx_destroyed(m)) { + td = mtx_owner(m); + db_printf(" owner: %p (tid %d, pid %d, \"%s\")\n", td, + td->td_tid, td->td_proc->p_pid, td->td_name); + if (mtx_recursed(m)) + db_printf(" recursed: %d\n", m->mtx_recurse); + } +} +#endif |
