FreeBSD-5.3/lib/libthr/thread/thr_mutex.c
/*
* Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by John Birrell.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``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 THE AUTHOR OR CONTRIBUTORS 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.
*
* $FreeBSD: src/lib/libthr/thread/thr_mutex.c,v 1.30.2.1 2004/10/09 15:13:50 mtm Exp $
*/
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <sys/param.h>
#include <sys/queue.h>
#include <pthread.h>
#include <time.h>
#include "thr_private.h"
#if defined(_PTHREADS_INVARIANTS)
#define _MUTEX_INIT_LINK(m) do { \
(m)->m_qe.tqe_prev = NULL; \
(m)->m_qe.tqe_next = NULL; \
} while (0)
#define _MUTEX_ASSERT_IS_OWNED(m) do { \
if ((m)->m_qe.tqe_prev == NULL) \
PANIC("mutex is not on list"); \
} while (0)
#define _MUTEX_ASSERT_NOT_OWNED(m) do { \
if (((m)->m_qe.tqe_prev != NULL) || \
((m)->m_qe.tqe_next != NULL)) \
PANIC("mutex is on list"); \
} while (0)
#else
#define _MUTEX_INIT_LINK(m)
#define _MUTEX_ASSERT_IS_OWNED(m)
#define _MUTEX_ASSERT_NOT_OWNED(m)
#endif
/*
* Prototypes
*/
static void acquire_mutex(struct pthread_mutex *, struct pthread *);
static int get_mcontested(pthread_mutex_t,
const struct timespec *);
static void mutex_attach_to_next_pthread(struct pthread_mutex *);
static int mutex_init(pthread_mutex_t *, int);
static int mutex_lock_common(pthread_mutex_t *, int,
const struct timespec *);
static inline int mutex_self_lock(pthread_mutex_t, int);
static inline int mutex_unlock_common(pthread_mutex_t *, int);
static inline pthread_t mutex_queue_deq(pthread_mutex_t);
static inline void mutex_queue_remove(pthread_mutex_t, pthread_t);
static inline void mutex_queue_enq(pthread_mutex_t, pthread_t);
static void restore_prio_inheritance(struct pthread *);
static void restore_prio_protection(struct pthread *);
static spinlock_t static_init_lock = _SPINLOCK_INITIALIZER;
static struct pthread_mutex_attr static_mutex_attr =
PTHREAD_MUTEXATTR_STATIC_INITIALIZER;
static pthread_mutexattr_t static_mattr = &static_mutex_attr;
/* Single underscore versions provided for libc internal usage: */
__weak_reference(__pthread_mutex_trylock, pthread_mutex_trylock);
__weak_reference(__pthread_mutex_lock, pthread_mutex_lock);
__weak_reference(__pthread_mutex_unlock, pthread_mutex_unlock);
/* No difference between libc and application usage of these: */
__weak_reference(_pthread_mutex_init, pthread_mutex_init);
__weak_reference(_pthread_mutex_destroy, pthread_mutex_destroy);
__weak_reference(_pthread_mutex_timedlock, pthread_mutex_timedlock);
/*
* Reinitialize a private mutex; this is only used for internal mutexes.
*/
int
_mutex_reinit(pthread_mutex_t * mutex)
{
int ret = 0;
if (*mutex == PTHREAD_MUTEX_INITIALIZER)
ret = _pthread_mutex_init(mutex, NULL);
else {
/*
* Initialize the mutex structure:
*/
(*mutex)->m_type = PTHREAD_MUTEX_DEFAULT;
(*mutex)->m_protocol = PTHREAD_PRIO_NONE;
TAILQ_INIT(&(*mutex)->m_queue);
(*mutex)->m_owner = NULL;
(*mutex)->m_data.m_count = 0;
(*mutex)->m_flags |= MUTEX_FLAGS_INITED | MUTEX_FLAGS_PRIVATE;
(*mutex)->m_refcount = 0;
(*mutex)->m_prio = 0;
(*mutex)->m_saved_prio = 0;
_MUTEX_INIT_LINK(*mutex);
memset(&(*mutex)->lock, 0, sizeof((*mutex)->lock));
}
return (ret);
}
int
_pthread_mutex_init(pthread_mutex_t * mutex,
const pthread_mutexattr_t * mutex_attr)
{
struct pthread_mutex_attr default_attr = {PTHREAD_MUTEX_ERRORCHECK,
PTHREAD_PRIO_NONE, PTHREAD_MAX_PRIORITY, 0 };
struct pthread_mutex_attr *attr;
if (mutex_attr == NULL) {
attr = &default_attr;
} else {
/*
* Check that the given mutex attribute is valid.
*/
if (((*mutex_attr)->m_type < PTHREAD_MUTEX_ERRORCHECK) ||
((*mutex_attr)->m_type >= MUTEX_TYPE_MAX))
return (EINVAL);
else if (((*mutex_attr)->m_protocol < PTHREAD_PRIO_NONE) ||
((*mutex_attr)->m_protocol > PTHREAD_MUTEX_RECURSIVE))
return (EINVAL);
attr = *mutex_attr;
}
if ((*mutex =
(pthread_mutex_t)malloc(sizeof(struct pthread_mutex))) == NULL)
return (ENOMEM);
memset((void *)(*mutex), 0, sizeof(struct pthread_mutex));
/* Initialise the rest of the mutex: */
TAILQ_INIT(&(*mutex)->m_queue);
_MUTEX_INIT_LINK(*mutex);
(*mutex)->m_protocol = attr->m_protocol;
(*mutex)->m_flags = (attr->m_flags | MUTEX_FLAGS_INITED);
(*mutex)->m_type = attr->m_type;
if ((*mutex)->m_protocol == PTHREAD_PRIO_PROTECT)
(*mutex)->m_prio = attr->m_ceiling;
return (0);
}
int
_pthread_mutex_destroy(pthread_mutex_t * mutex)
{
/*
* If this mutex was statically initialized, don't bother
* initializing it in order to destroy it immediately.
*/
if (*mutex == PTHREAD_MUTEX_INITIALIZER)
return (0);
/* Lock the mutex structure: */
_SPINLOCK(&(*mutex)->lock);
/*
* Check to see if this mutex is in use:
*/
if (((*mutex)->m_owner != NULL) ||
(TAILQ_FIRST(&(*mutex)->m_queue) != NULL) ||
((*mutex)->m_refcount != 0)) {
/* Unlock the mutex structure: */
_SPINUNLOCK(&(*mutex)->lock);
return (EBUSY);
}
/*
* Free the memory allocated for the mutex
* structure:
*/
_MUTEX_ASSERT_NOT_OWNED(*mutex);
_SPINUNLOCK(&(*mutex)->lock);
free(*mutex);
/*
* Leave the caller's pointer NULL now that
* the mutex has been destroyed:
*/
*mutex = NULL;
return (0);
}
static int
mutex_init(pthread_mutex_t *mutex, int private)
{
pthread_mutexattr_t *pma;
int error;
error = 0;
pma = private ? &static_mattr : NULL;
_SPINLOCK(&static_init_lock);
if (*mutex == PTHREAD_MUTEX_INITIALIZER)
error = _pthread_mutex_init(mutex, pma);
_SPINUNLOCK(&static_init_lock);
return (error);
}
/*
* Acquires a mutex for the current thread. The caller must
* lock the mutex before calling this function.
*/
static void
acquire_mutex(struct pthread_mutex *mtx, struct pthread *ptd)
{
mtx->m_owner = ptd;
_MUTEX_ASSERT_NOT_OWNED(mtx);
PTHREAD_LOCK(ptd);
TAILQ_INSERT_TAIL(&ptd->mutexq, mtx, m_qe);
PTHREAD_UNLOCK(ptd);
}
/*
* Releases a mutex from the current thread. The owner must
* lock the mutex. The next thread on the queue will be returned
* locked by the current thread. The caller must take care to
* unlock it.
*/
static void
mutex_attach_to_next_pthread(struct pthread_mutex *mtx)
{
struct pthread *ptd;
_MUTEX_ASSERT_IS_OWNED(mtx);
TAILQ_REMOVE(&mtx->m_owner->mutexq, (mtx), m_qe);
_MUTEX_INIT_LINK(mtx);
/*
* Deque next thread waiting for this mutex and attach
* the mutex to it. The thread will already be locked.
*/
if ((ptd = mutex_queue_deq(mtx)) != NULL) {
TAILQ_INSERT_TAIL(&ptd->mutexq, mtx, m_qe);
ptd->data.mutex = NULL;
PTHREAD_WAKE(ptd);
}
mtx->m_owner = ptd;
}
int
__pthread_mutex_trylock(pthread_mutex_t *mutex)
{
int ret = 0;
/*
* If the mutex is statically initialized, perform the dynamic
* initialization:
*/
if ((*mutex != PTHREAD_MUTEX_INITIALIZER) ||
(ret = mutex_init(mutex, 0)) == 0)
ret = mutex_lock_common(mutex, 1, NULL);
return (ret);
}
/*
* Libc internal.
*/
int
_pthread_mutex_trylock(pthread_mutex_t *mutex)
{
int ret = 0;
/*
* If the mutex is statically initialized, perform the dynamic
* initialization marking the mutex private (delete safe):
*/
if ((*mutex != PTHREAD_MUTEX_INITIALIZER) ||
(ret = mutex_init(mutex, 1)) == 0)
ret = mutex_lock_common(mutex, 1, NULL);
return (ret);
}
static int
mutex_lock_common(pthread_mutex_t * mutex, int nonblock,
const struct timespec *abstime)
{
int error;
error = 0;
PTHREAD_ASSERT((mutex != NULL) && (*mutex != NULL),
"Uninitialized mutex in mutex_lock_common");
PTHREAD_ASSERT(((*mutex)->m_protocol >= PTHREAD_PRIO_NONE &&
(*mutex)->m_protocol <= PTHREAD_PRIO_PROTECT),
"Invalid mutex protocol");
_SPINLOCK(&(*mutex)->lock);
/*
* If the mutex was statically allocated, properly
* initialize the tail queue.
*/
if (((*mutex)->m_flags & MUTEX_FLAGS_INITED) == 0) {
TAILQ_INIT(&(*mutex)->m_queue);
(*mutex)->m_flags |= MUTEX_FLAGS_INITED;
_MUTEX_INIT_LINK(*mutex);
}
retry:
/*
* If the mutex is a priority protected mutex the thread's
* priority may not be higher than that of the mutex.
*/
if ((*mutex)->m_protocol == PTHREAD_PRIO_PROTECT &&
curthread->active_priority > (*mutex)->m_prio) {
_SPINUNLOCK(&(*mutex)->lock);
return (EINVAL);
}
if ((*mutex)->m_owner == NULL) {
/*
* Mutex is currently unowned.
*/
acquire_mutex(*mutex, curthread);
} else if ((*mutex)->m_owner == curthread) {
/*
* Mutex is owned by curthread. We must test against
* certain conditions in such a case.
*/
if ((error = mutex_self_lock((*mutex), nonblock)) != 0) {
_SPINUNLOCK(&(*mutex)->lock);
return (error);
}
} else {
if (nonblock) {
error = EBUSY;
goto out;
}
/*
* Another thread owns the mutex. This thread must
* wait for that thread to unlock the mutex. This
* thread must not return to the caller if it was
* interrupted by a signal.
*/
error = get_mcontested(*mutex, abstime);
if (error == EINTR)
goto retry;
else if (error == ETIMEDOUT)
goto out;
}
if ((*mutex)->m_type == PTHREAD_MUTEX_RECURSIVE)
(*mutex)->m_data.m_count++;
/*
* The mutex is now owned by curthread.
*/
PTHREAD_LOCK(curthread);
/*
* The mutex's priority may have changed while waiting for it.
*/
if ((*mutex)->m_protocol == PTHREAD_PRIO_PROTECT &&
curthread->active_priority > (*mutex)->m_prio) {
mutex_attach_to_next_pthread(*mutex);
if ((*mutex)->m_owner != NULL)
PTHREAD_UNLOCK((*mutex)->m_owner);
PTHREAD_UNLOCK(curthread);
_SPINUNLOCK(&(*mutex)->lock);
return (EINVAL);
}
switch ((*mutex)->m_protocol) {
case PTHREAD_PRIO_INHERIT:
curthread->prio_inherit_count++;
break;
case PTHREAD_PRIO_PROTECT:
PTHREAD_ASSERT((curthread->active_priority <=
(*mutex)->m_prio), "priority protection violation");
curthread->prio_protect_count++;
if ((*mutex)->m_prio > curthread->active_priority) {
curthread->inherited_priority = (*mutex)->m_prio;
curthread->active_priority = (*mutex)->m_prio;
}
break;
default:
/* Nothing */
break;
}
PTHREAD_UNLOCK(curthread);
out:
_SPINUNLOCK(&(*mutex)->lock);
return (error);
}
/*
* Caller must lock thread.
*/
void
adjust_prio_inheritance(struct pthread *ptd)
{
struct pthread_mutex *tempMtx;
struct pthread *tempTd;
/*
* Scan owned mutexes's wait queue and execute at the
* higher of thread's current priority or the priority of
* the highest priority thread waiting on any of the the
* mutexes the thread owns. Note: the highest priority thread
* on a queue is always at the head of the queue.
*/
TAILQ_FOREACH(tempMtx, &ptd->mutexq, m_qe) {
if (tempMtx->m_protocol != PTHREAD_PRIO_INHERIT)
continue;
/*
* XXX LOR with respect to tempMtx and ptd.
* Order should be: 1. mutex
* 2. pthread
*/
_SPINLOCK(&tempMtx->lock);
tempTd = TAILQ_FIRST(&tempMtx->m_queue);
if (tempTd != NULL) {
PTHREAD_LOCK(tempTd);
if (tempTd->active_priority > ptd->active_priority) {
ptd->inherited_priority =
tempTd->active_priority;
ptd->active_priority =
tempTd->active_priority;
}
PTHREAD_UNLOCK(tempTd);
}
_SPINUNLOCK(&tempMtx->lock);
}
}
/*
* Caller must lock thread.
*/
static void
restore_prio_inheritance(struct pthread *ptd)
{
ptd->inherited_priority = PTHREAD_MIN_PRIORITY;
ptd->active_priority = ptd->base_priority;
adjust_prio_inheritance(ptd);
}
/*
* Caller must lock thread.
*/
void
adjust_prio_protection(struct pthread *ptd)
{
struct pthread_mutex *tempMtx;
/*
* The thread shall execute at the higher of its priority or
* the highest priority ceiling of all the priority protection
* mutexes it owns.
*/
TAILQ_FOREACH(tempMtx, &ptd->mutexq, m_qe) {
if (tempMtx->m_protocol != PTHREAD_PRIO_PROTECT)
continue;
if (ptd->active_priority < tempMtx->m_prio) {
ptd->inherited_priority = tempMtx->m_prio;
ptd->active_priority = tempMtx->m_prio;
}
}
}
/*
* Caller must lock thread.
*/
static void
restore_prio_protection(struct pthread *ptd)
{
ptd->inherited_priority = PTHREAD_MIN_PRIORITY;
ptd->active_priority = ptd->base_priority;
adjust_prio_protection(ptd);
}
int
__pthread_mutex_lock(pthread_mutex_t *mutex)
{
int ret = 0;
if (_thread_initial == NULL)
_thread_init();
/*
* If the mutex is statically initialized, perform the dynamic
* initialization:
*/
if ((*mutex != PTHREAD_MUTEX_INITIALIZER) ||
((ret = mutex_init(mutex, 0)) == 0))
ret = mutex_lock_common(mutex, 0, NULL);
return (ret);
}
/*
* Libc internal.
*/
int
_pthread_mutex_lock(pthread_mutex_t *mutex)
{
int ret = 0;
if (_thread_initial == NULL)
_thread_init();
/*
* If the mutex is statically initialized, perform the dynamic
* initialization marking it private (delete safe):
*/
if ((*mutex != PTHREAD_MUTEX_INITIALIZER) ||
((ret = mutex_init(mutex, 1)) == 0))
ret = mutex_lock_common(mutex, 0, NULL);
return (ret);
}
int
_pthread_mutex_timedlock(pthread_mutex_t *mutex, const struct timespec *abstime)
{
int error;
error = 0;
if (_thread_initial == NULL)
_thread_init();
/*
* Initialize it if it's a valid statically inited mutex.
*/
if ((*mutex != PTHREAD_MUTEX_INITIALIZER) ||
((error = mutex_init(mutex, 0)) == 0))
error = mutex_lock_common(mutex, 0, abstime);
PTHREAD_ASSERT(error != EINTR, "According to SUSv3 this function shall not return an error code of EINTR");
return (error);
}
int
__pthread_mutex_unlock(pthread_mutex_t * mutex)
{
return (mutex_unlock_common(mutex, /* add reference */ 0));
}
/*
* Libc internal
*/
int
_pthread_mutex_unlock(pthread_mutex_t * mutex)
{
return (mutex_unlock_common(mutex, /* add reference */ 0));
}
int
_mutex_cv_unlock(pthread_mutex_t * mutex)
{
return (mutex_unlock_common(mutex, /* add reference */ 1));
}
int
_mutex_cv_lock(pthread_mutex_t * mutex)
{
int ret;
if ((ret = _pthread_mutex_lock(mutex)) == 0)
(*mutex)->m_refcount--;
return (ret);
}
/*
* Caller must lock mutex and then disable signals and lock curthread.
*/
static inline int
mutex_self_lock(pthread_mutex_t mutex, int noblock)
{
switch (mutex->m_type) {
case PTHREAD_MUTEX_ERRORCHECK:
/*
* POSIX specifies that mutexes should return EDEADLK if a
* recursive lock is detected.
*/
if (noblock)
return (EBUSY);
return (EDEADLK);
break;
case PTHREAD_MUTEX_NORMAL:
/*
* What SS2 define as a 'normal' mutex. Intentionally
* deadlock on attempts to get a lock you already own.
*/
if (noblock)
return (EBUSY);
curthread->isdeadlocked = 1;
_SPINUNLOCK(&(mutex)->lock);
_thread_suspend(curthread, NULL);
PANIC("Shouldn't resume here?\n");
break;
default:
/* Do Nothing */
break;
}
return (0);
}
static inline int
mutex_unlock_common(pthread_mutex_t * mutex, int add_reference)
{
/*
* Error checking.
*/
if ((*mutex)->m_owner != curthread)
return (EPERM);
PTHREAD_ASSERT(((*mutex)->m_protocol >= PTHREAD_PRIO_NONE &&
(*mutex)->m_protocol <= PTHREAD_PRIO_PROTECT),
"Invalid mutex protocol");
_SPINLOCK(&(*mutex)->lock);
if ((*mutex)->m_type == PTHREAD_MUTEX_RECURSIVE) {
(*mutex)->m_data.m_count--;
PTHREAD_ASSERT((*mutex)->m_data.m_count >= 0,
"The mutex recurse count cannot be less than zero");
if ((*mutex)->m_data.m_count > 0) {
_SPINUNLOCK(&(*mutex)->lock);
return (0);
}
}
/*
* Release the mutex from this thread and attach it to
* the next thread in the queue, if there is one waiting.
*/
PTHREAD_LOCK(curthread);
mutex_attach_to_next_pthread(*mutex);
if ((*mutex)->m_owner != NULL)
PTHREAD_UNLOCK((*mutex)->m_owner);
if (add_reference != 0) {
/* Increment the reference count: */
(*mutex)->m_refcount++;
}
_SPINUNLOCK(&(*mutex)->lock);
/*
* Fix priority of the thread that just released the mutex.
*/
switch ((*mutex)->m_protocol) {
case PTHREAD_PRIO_INHERIT:
curthread->prio_inherit_count--;
PTHREAD_ASSERT(curthread->prio_inherit_count >= 0,
"priority inheritance counter cannot be less than zero");
restore_prio_inheritance(curthread);
if (curthread->prio_protect_count > 0)
restore_prio_protection(curthread);
break;
case PTHREAD_PRIO_PROTECT:
curthread->prio_protect_count--;
PTHREAD_ASSERT(curthread->prio_protect_count >= 0,
"priority protection counter cannot be less than zero");
restore_prio_protection(curthread);
if (curthread->prio_inherit_count > 0)
restore_prio_inheritance(curthread);
break;
default:
/* Nothing */
break;
}
PTHREAD_UNLOCK(curthread);
return (0);
}
void
_mutex_unlock_private(pthread_t pthread)
{
struct pthread_mutex *m, *m_next;
for (m = TAILQ_FIRST(&pthread->mutexq); m != NULL; m = m_next) {
m_next = TAILQ_NEXT(m, m_qe);
if ((m->m_flags & MUTEX_FLAGS_PRIVATE) != 0)
_pthread_mutex_unlock(&m);
}
}
void
_mutex_lock_backout(pthread_t pthread)
{
struct pthread_mutex *mutex;
mutex = pthread->data.mutex;
if ((pthread->flags & PTHREAD_FLAGS_IN_MUTEXQ) != 0) {
mutex_queue_remove(mutex, pthread);
/* This thread is no longer waiting for the mutex: */
pthread->data.mutex = NULL;
}
}
/*
* Dequeue a waiting thread from the head of a mutex queue in descending
* priority order. This funtion will return with the thread locked.
*/
static inline pthread_t
mutex_queue_deq(pthread_mutex_t mutex)
{
pthread_t pthread;
while ((pthread = TAILQ_FIRST(&mutex->m_queue)) != NULL) {
PTHREAD_LOCK(pthread);
TAILQ_REMOVE(&mutex->m_queue, pthread, sqe);
pthread->flags &= ~PTHREAD_FLAGS_IN_MUTEXQ;
/*
* Only exit the loop if the thread hasn't been
* asynchronously cancelled.
*/
if (pthread->cancelmode == M_ASYNC &&
pthread->cancellation != CS_NULL)
continue;
else
break;
}
return (pthread);
}
/*
* Remove a waiting thread from a mutex queue in descending priority order.
*/
static inline void
mutex_queue_remove(pthread_mutex_t mutex, pthread_t pthread)
{
if ((pthread->flags & PTHREAD_FLAGS_IN_MUTEXQ) != 0) {
TAILQ_REMOVE(&mutex->m_queue, pthread, sqe);
pthread->flags &= ~PTHREAD_FLAGS_IN_MUTEXQ;
}
}
/*
* Enqueue a waiting thread to a queue in descending priority order.
*/
static inline void
mutex_queue_enq(pthread_mutex_t mutex, pthread_t pthread)
{
pthread_t tid = TAILQ_LAST(&mutex->m_queue, mutex_head);
char *name;
name = pthread->name ? pthread->name : "unknown";
if ((pthread->flags & PTHREAD_FLAGS_IN_CONDQ) != 0)
_thread_printf(2, "Thread (%s:%ld) already on condq\n",
pthread->name, pthread->thr_id);
if ((pthread->flags & PTHREAD_FLAGS_IN_MUTEXQ) != 0)
_thread_printf(2, "Thread (%s:%ld) already on mutexq\n",
pthread->name, pthread->thr_id);
PTHREAD_ASSERT_NOT_IN_SYNCQ(pthread);
/*
* For the common case of all threads having equal priority,
* we perform a quick check against the priority of the thread
* at the tail of the queue.
*/
if ((tid == NULL) || (pthread->active_priority <= tid->active_priority))
TAILQ_INSERT_TAIL(&mutex->m_queue, pthread, sqe);
else {
tid = TAILQ_FIRST(&mutex->m_queue);
while (pthread->active_priority <= tid->active_priority)
tid = TAILQ_NEXT(tid, sqe);
TAILQ_INSERT_BEFORE(tid, pthread, sqe);
}
if (mutex->m_protocol == PTHREAD_PRIO_INHERIT &&
pthread == TAILQ_FIRST(&mutex->m_queue)) {
PTHREAD_LOCK(mutex->m_owner);
if (pthread->active_priority >
mutex->m_owner->active_priority) {
mutex->m_owner->inherited_priority =
pthread->active_priority;
mutex->m_owner->active_priority =
pthread->active_priority;
}
PTHREAD_UNLOCK(mutex->m_owner);
}
pthread->flags |= PTHREAD_FLAGS_IN_MUTEXQ;
}
/*
* Caller must lock mutex and pthread.
*/
void
readjust_priorities(struct pthread *pthread, struct pthread_mutex *mtx)
{
if ((pthread->flags & PTHREAD_FLAGS_IN_MUTEXQ) != 0) {
PTHREAD_ASSERT(mtx != NULL,
"mutex is NULL when it should not be");
mutex_queue_remove(mtx, pthread);
mutex_queue_enq(mtx, pthread);
PTHREAD_LOCK(mtx->m_owner);
adjust_prio_inheritance(mtx->m_owner);
if (mtx->m_owner->prio_protect_count > 0)
adjust_prio_protection(mtx->m_owner);
PTHREAD_UNLOCK(mtx->m_owner);
}
if (pthread->prio_inherit_count > 0)
adjust_prio_inheritance(pthread);
if (pthread->prio_protect_count > 0)
adjust_prio_protection(pthread);
}
/*
* Returns with the lock owned and on the thread's mutexq. If
* the mutex is currently owned by another thread it will sleep
* until it is available.
*/
static int
get_mcontested(pthread_mutex_t mutexp, const struct timespec *abstime)
{
int error;
/*
* If the timeout is invalid this thread is not allowed
* to block;
*/
if (abstime != NULL) {
if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000)
return (EINVAL);
}
/*
* Put this thread on the mutex's list of waiting threads.
* The lock on the thread ensures atomic (as far as other
* threads are concerned) setting of the thread state with
* it's status on the mutex queue.
*/
PTHREAD_LOCK(curthread);
mutex_queue_enq(mutexp, curthread);
do {
if (curthread->cancelmode == M_ASYNC &&
curthread->cancellation != CS_NULL) {
mutex_queue_remove(mutexp, curthread);
PTHREAD_UNLOCK(curthread);
_SPINUNLOCK(&mutexp->lock);
pthread_testcancel();
}
curthread->data.mutex = mutexp;
PTHREAD_UNLOCK(curthread);
_SPINUNLOCK(&mutexp->lock);
error = _thread_suspend(curthread, abstime);
if (error != 0 && error != ETIMEDOUT && error != EINTR)
PANIC("Cannot suspend on mutex.");
_SPINLOCK(&mutexp->lock);
PTHREAD_LOCK(curthread);
if (error == ETIMEDOUT) {
/*
* Between the timeout and when the mutex was
* locked the previous owner may have released
* the mutex to this thread. Or not.
*/
if (mutexp->m_owner == curthread)
error = 0;
else
_mutex_lock_backout(curthread);
}
} while ((curthread->flags & PTHREAD_FLAGS_IN_MUTEXQ) != 0);
PTHREAD_UNLOCK(curthread);
return (error);
}