diff options
Diffstat (limited to 'sys/kern/subr_turnstile.c')
| -rw-r--r-- | sys/kern/subr_turnstile.c | 986 |
1 files changed, 986 insertions, 0 deletions
diff --git a/sys/kern/subr_turnstile.c b/sys/kern/subr_turnstile.c new file mode 100644 index 0000000..08bca8d --- /dev/null +++ b/sys/kern/subr_turnstile.c @@ -0,0 +1,986 @@ +/*- + * 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 $ + * $FreeBSD$ + */ + +/* + * Machine independent bits of mutex implementation. + */ + +#include "opt_adaptive_mutexes.h" +#include "opt_ddb.h" + +#include <sys/param.h> +#include <sys/systm.h> +#include <sys/bus.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/sbuf.h> +#include <sys/stdint.h> +#include <sys/sysctl.h> +#include <sys/vmmeter.h> + +#include <machine/atomic.h> +#include <machine/bus.h> +#include <machine/clock.h> +#include <machine/cpu.h> + +#include <ddb/ddb.h> + +#include <vm/vm.h> +#include <vm/vm_extern.h> + +/* + * 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)) + +/* XXXKSE This test will change. */ +#define thread_running(td) \ + ((td)->td_kse != NULL && (td)->td_kse->ke_oncpu != NOCPU) + +/* + * 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; + +/* + * Prototypes for non-exported routines. + */ +static void propagate_priority(struct thread *); + +static void +propagate_priority(struct thread *td) +{ + int pri = td->td_priority; + struct mtx *m = td->td_blocked; + + mtx_assert(&sched_lock, MA_OWNED); + for (;;) { + struct thread *td1; + + td = mtx_owner(m); + + if (td == NULL) { + /* + * This really isn't quite right. Really + * ought to bump priority of thread that + * next acquires the mutex. + */ + MPASS(m->mtx_lock == MTX_CONTESTED); + return; + } + + MPASS(td->td_proc->p_magic == P_MAGIC); + KASSERT(td->td_proc->p_stat != SSLEEP, ("sleeping thread owns a mutex")); + if (td->td_priority <= pri) /* lower is higher priority */ + return; + + /* + * Bump this thread's priority. + */ + td->td_priority = pri; + + /* + * If lock holder is actually running, just bump priority. + */ + if (thread_running(td)) { + MPASS(td->td_proc->p_stat == SRUN + || td->td_proc->p_stat == SZOMB + || td->td_proc->p_stat == SSTOP); + return; + } + +#ifndef SMP + /* + * For UP, we check to see if td is curthread (this shouldn't + * ever happen however as it would mean we are in a deadlock.) + */ + KASSERT(td != curthread, ("Deadlock detected")); +#endif + + /* + * If on run queue move to new run queue, and quit. + * XXXKSE this gets a lot more complicated under threads + * but try anyhow. + */ + if (td->td_proc->p_stat == SRUN) { + MPASS(td->td_blocked == NULL); + remrunqueue(td); + setrunqueue(td); + return; + } + + /* + * If we aren't blocked on a mutex, we should be. + */ + KASSERT(td->td_proc->p_stat == SMTX, ( + "process %d(%s):%d holds %s but isn't blocked on a mutex\n", + td->td_proc->p_pid, td->td_proc->p_comm, td->td_proc->p_stat, + m->mtx_object.lo_name)); + + /* + * Pick up the mutex that td is blocked on. + */ + m = td->td_blocked; + MPASS(m != NULL); + + /* + * Check if the thread needs to be moved up on + * the blocked chain + */ + if (td == TAILQ_FIRST(&m->mtx_blocked)) { + continue; + } + + td1 = TAILQ_PREV(td, threadqueue, td_blkq); + if (td1->td_priority <= pri) { + continue; + } + + /* + * Remove thread from blocked chain and determine where + * it should be moved up to. Since we know that td1 has + * a lower priority than td, we know that at least one + * thread in the chain has a lower priority and that + * td1 will thus not be NULL after the loop. + */ + TAILQ_REMOVE(&m->mtx_blocked, td, td_blkq); + TAILQ_FOREACH(td1, &m->mtx_blocked, td_blkq) { + MPASS(td1->td_proc->p_magic == P_MAGIC); + if (td1->td_priority > pri) + break; + } + + MPASS(td1 != NULL); + TAILQ_INSERT_BEFORE(td1, td, td_blkq); + CTR4(KTR_LOCK, + "propagate_priority: p %p moved before %p on [%p] %s", + td, td1, m, m->mtx_object.lo_name); + } +} + +#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; +#define MPROF_MAX 0 +#define MPROF_TOT 1 +#define MPROF_CNT 2 +#define MPROF_AVG 3 + uintmax_t counter[4]; + 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]; + +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; + + if (first_free_mprof_buf == 0) + return SYSCTL_OUT(req, "No locking recorded", + sizeof("No locking recorded")); + + sb = sbuf_new(NULL, NULL, 1024, SBUF_AUTOEXTEND); + sbuf_printf(sb, "%12s %12s %12s %12s %s\n", + "max", "total", "count", "average", "name"); + mtx_lock_spin(&mprof_mtx); + for (i = 0; i < first_free_mprof_buf; ++i) + sbuf_printf(sb, "%12ju %12ju %12ju %12ju %s:%d (%s)\n", + mprof_buf[i].counter[MPROF_MAX] / 1000, + mprof_buf[i].counter[MPROF_TOT] / 1000, + mprof_buf[i].counter[MPROF_CNT], + mprof_buf[i].counter[MPROF_AVG] / 1000, + mprof_buf[i].file, mprof_buf[i].line, mprof_buf[i].name); + 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"); +#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); + _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->acqtime == 0) { + m->file = file; + m->line = line; + m->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); + mtx_assert(m, MA_OWNED); +#ifdef MUTEX_PROFILING + if (m->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->acqtime; + m->acqtime = 0; + if (now <= acqtime) + goto out; + for (p = file; strncmp(p, "../", 3) == 0; p += 3) + /* nothing */ ; + if (p == NULL || *p == '\0') + p = unknown; + for (hash = line, 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 == line && 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 = line; + 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->counter[MPROF_MAX]) + mpp->counter[MPROF_MAX] = now - acqtime; + mpp->counter[MPROF_TOT] += now - acqtime; + mpp->counter[MPROF_CNT] += 1; + mpp->counter[MPROF_AVG] = + mpp->counter[MPROF_TOT] / mpp->counter[MPROF_CNT]; +unlock: + mtx_unlock_spin(&mprof_mtx); + } +out: +#endif + WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); + LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file, + line); + _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); +#if defined(SMP) || LOCK_DEBUG > 0 + _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); + mtx_assert(m, MA_OWNED); + WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line); + LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file, + line); +#if defined(SMP) || LOCK_DEBUG > 0 + _rel_spin_lock(m); +#else + critical_exit(); +#endif +} + +/* + * The important part of mtx_trylock{,_flags}() + * Tries to acquire lock `m.' We do NOT handle recursion here; we assume that + * if we're called, it's because we know we don't already own this lock. + */ +int +_mtx_trylock(struct mtx *m, int opts, const char *file, int line) +{ + int rval; + + MPASS(curthread != NULL); + + rval = _obtain_lock(m, curthread); + + LOCK_LOG_TRY("LOCK", &m->mtx_object, opts, rval, file, line); + if (rval) { + /* + * We do not handle recursion in _mtx_trylock; see the + * note at the top of the routine. + */ + KASSERT(!mtx_recursed(m), + ("mtx_trylock() called on a recursed mutex")); + 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 thread *td = curthread; +#if defined(SMP) && defined(ADAPTIVE_MUTEXES) + struct thread *owner; +#endif + + if ((m->mtx_lock & MTX_FLAGMASK) == (uintptr_t)td) { + 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); + + while (!_obtain_lock(m, td)) { + uintptr_t v; + struct thread *td1; + + mtx_lock_spin(&sched_lock); + /* + * Check if the lock has been released while spinning for + * the sched_lock. + */ + if ((v = m->mtx_lock) == MTX_UNOWNED) { + mtx_unlock_spin(&sched_lock); +#ifdef __i386__ + ia32_pause(); +#endif + continue; + } + + /* + * The mutex was marked contested on release. This means that + * there are threads blocked on it. + */ + if (v == MTX_CONTESTED) { + td1 = TAILQ_FIRST(&m->mtx_blocked); + MPASS(td1 != NULL); + m->mtx_lock = (uintptr_t)td | MTX_CONTESTED; + + if (td1->td_priority < td->td_priority) + td->td_priority = td1->td_priority; + mtx_unlock_spin(&sched_lock); + return; + } + + /* + * 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))) { + mtx_unlock_spin(&sched_lock); +#ifdef __i386__ + ia32_pause(); +#endif + continue; + } + +#if defined(SMP) && defined(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 && thread_running(owner)) { + mtx_unlock_spin(&sched_lock); + while (mtx_owner(m) == owner && thread_running(owner)) { +#ifdef __i386__ + ia32_pause(); +#endif + } + continue; + } +#endif /* SMP && ADAPTIVE_MUTEXES */ + + /* + * We definitely must sleep for this lock. + */ + mtx_assert(m, MA_NOTOWNED); + +#ifdef notyet + /* + * If we're borrowing an interrupted thread's VM context, we + * must clean up before going to sleep. + */ + 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_lock_sleep: %p interrupted %p", + it, it->it_interrupted); + intr_thd_fixup(it); + } + } +#endif + + /* + * Put us on the list of threads blocked on this mutex. + */ + if (TAILQ_EMPTY(&m->mtx_blocked)) { + td1 = mtx_owner(m); + LIST_INSERT_HEAD(&td1->td_contested, m, mtx_contested); + TAILQ_INSERT_TAIL(&m->mtx_blocked, td, td_blkq); + } else { + TAILQ_FOREACH(td1, &m->mtx_blocked, td_blkq) + if (td1->td_priority > td->td_priority) + break; + if (td1) + TAILQ_INSERT_BEFORE(td1, td, td_blkq); + else + TAILQ_INSERT_TAIL(&m->mtx_blocked, td, td_blkq); + } + + /* + * Save who we're blocked on. + */ + td->td_blocked = m; + td->td_mtxname = m->mtx_object.lo_name; + td->td_proc->p_stat = SMTX; + propagate_priority(td); + + if (LOCK_LOG_TEST(&m->mtx_object, opts)) + CTR3(KTR_LOCK, + "_mtx_lock_sleep: p %p blocked on [%p] %s", td, m, + m->mtx_object.lo_name); + + td->td_proc->p_stats->p_ru.ru_nvcsw++; + mi_switch(); + + if (LOCK_LOG_TEST(&m->mtx_object, opts)) + CTR3(KTR_LOCK, + "_mtx_lock_sleep: p %p free from blocked on [%p] %s", + td, m, m->mtx_object.lo_name); + + mtx_unlock_spin(&sched_lock); + } + + 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) { +#ifdef __i386__ + ia32_pause(); +#endif + continue; + } + if (i < 60000000) + DELAY(1); +#ifdef DDB + else if (!db_active) +#else + else +#endif + panic("spin lock %s held by %p for > 5 seconds", + m->mtx_object.lo_name, (void *)m->mtx_lock); +#ifdef __i386__ + 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 thread *td, *td1; + struct mtx *m1; + int pri; + + td = curthread; + + 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; + } + + mtx_lock_spin(&sched_lock); + if (LOCK_LOG_TEST(&m->mtx_object, opts)) + CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m); + + td1 = TAILQ_FIRST(&m->mtx_blocked); +#if defined(SMP) && defined(ADAPTIVE_MUTEXES) + if (td1 == NULL) { + _release_lock_quick(m); + if (LOCK_LOG_TEST(&m->mtx_object, opts)) + CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m); + mtx_unlock_spin(&sched_lock); + return; + } +#endif + MPASS(td->td_proc->p_magic == P_MAGIC); + MPASS(td1->td_proc->p_magic == P_MAGIC); + + TAILQ_REMOVE(&m->mtx_blocked, td1, td_blkq); + + if (TAILQ_EMPTY(&m->mtx_blocked)) { + LIST_REMOVE(m, mtx_contested); + _release_lock_quick(m); + if (LOCK_LOG_TEST(&m->mtx_object, opts)) + CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m); + } else + atomic_store_rel_ptr(&m->mtx_lock, (void *)MTX_CONTESTED); + + pri = PRI_MAX; + LIST_FOREACH(m1, &td->td_contested, mtx_contested) { + int cp = TAILQ_FIRST(&m1->mtx_blocked)->td_priority; + if (cp < pri) + pri = cp; + } + + if (pri > td->td_base_pri) + pri = td->td_base_pri; + td->td_priority = pri; + + if (LOCK_LOG_TEST(&m->mtx_object, opts)) + CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p contested setrunqueue %p", + m, td1); + + td1->td_blocked = NULL; + td1->td_proc->p_stat = SRUN; + setrunqueue(td1); + + if (td->td_critnest == 1 && td1->td_priority < pri) { +#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 + setrunqueue(td); + if (LOCK_LOG_TEST(&m->mtx_object, opts)) + CTR2(KTR_LOCK, + "_mtx_unlock_sleep: %p switching out lock=%p", m, + (void *)m->mtx_lock); + + td->td_proc->p_stats->p_ru.ru_nivcsw++; + mi_switch(); + 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); + + 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() 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 + +/* + * 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_SLEEPABLE | 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_SLEEPABLE) + lock->lo_flags |= LO_SLEEPABLE; + if ((opts & MTX_NOWITNESS) == 0) + lock->lo_flags |= LO_WITNESS; + if (opts & MTX_DUPOK) + lock->lo_flags |= LO_DUPOK; + + m->mtx_lock = MTX_UNOWNED; + TAILQ_INIT(&m->mtx_blocked); + + 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); + + /* + * 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); +} + +/* + * Encapsulated Giant mutex routines. These routines provide encapsulation + * control for the Giant mutex, allowing sysctls to be used to turn on and + * off Giant around certain subsystems. The default value for the sysctls + * are set to what developers believe is stable and working in regards to + * the Giant pushdown. Developers should not turn off Giant via these + * sysctls unless they know what they are doing. + * + * Callers of mtx_lock_giant() are expected to pass the return value to an + * accompanying mtx_unlock_giant() later on. If multiple subsystems are + * effected by a Giant wrap, all related sysctl variables must be zero for + * the subsystem call to operate without Giant (as determined by the caller). + */ + +SYSCTL_NODE(_kern, OID_AUTO, giant, CTLFLAG_RD, NULL, "Giant mutex manipulation"); + +static int kern_giant_all = 0; +SYSCTL_INT(_kern_giant, OID_AUTO, all, CTLFLAG_RW, &kern_giant_all, 0, ""); + +int kern_giant_proc = 1; /* Giant around PROC locks */ +int kern_giant_file = 1; /* Giant around struct file & filedesc */ +int kern_giant_ucred = 1; /* Giant around ucred */ +SYSCTL_INT(_kern_giant, OID_AUTO, proc, CTLFLAG_RW, &kern_giant_proc, 0, ""); +SYSCTL_INT(_kern_giant, OID_AUTO, file, CTLFLAG_RW, &kern_giant_file, 0, ""); +SYSCTL_INT(_kern_giant, OID_AUTO, ucred, CTLFLAG_RW, &kern_giant_ucred, 0, ""); + +int +mtx_lock_giant(int sysctlvar) +{ + if (sysctlvar || kern_giant_all) { + mtx_lock(&Giant); + return(1); + } + return(0); +} + +void +mtx_unlock_giant(int s) +{ + if (s) + mtx_unlock(&Giant); +} + |
