diff options
Diffstat (limited to 'lib/libpthread/thread/thr_mutex.c')
| -rw-r--r-- | lib/libpthread/thread/thr_mutex.c | 1758 |
1 files changed, 1758 insertions, 0 deletions
diff --git a/lib/libpthread/thread/thr_mutex.c b/lib/libpthread/thread/thr_mutex.c new file mode 100644 index 0000000..1232f33 --- /dev/null +++ b/lib/libpthread/thread/thr_mutex.c @@ -0,0 +1,1758 @@ +/* + * 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. + * + * $FreeBSD$ + */ +#include <stdlib.h> +#include <errno.h> +#include <string.h> +#include <sys/param.h> +#include <sys/queue.h> +#include <pthread.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) +#define THR_ASSERT_NOT_IN_SYNCQ(thr) do { \ + THR_ASSERT(((thr)->sflags & THR_FLAGS_IN_SYNCQ) == 0, \ + "thread in syncq when it shouldn't be."); \ +} while (0); +#else +#define MUTEX_INIT_LINK(m) +#define MUTEX_ASSERT_IS_OWNED(m) +#define MUTEX_ASSERT_NOT_OWNED(m) +#define THR_ASSERT_NOT_IN_SYNCQ(thr) +#endif + +#define THR_IN_MUTEXQ(thr) (((thr)->sflags & THR_FLAGS_IN_SYNCQ) != 0) +#define MUTEX_DESTROY(m) do { \ + _lock_destroy(&(m)->m_lock); \ + free(m); \ +} while (0) + + +/* + * Prototypes + */ +static struct kse_mailbox *mutex_handoff(struct pthread *, + struct pthread_mutex *); +static inline int mutex_self_trylock(struct pthread *, pthread_mutex_t); +static inline int mutex_self_lock(struct pthread *, pthread_mutex_t); +static int mutex_unlock_common(pthread_mutex_t *, int); +static void mutex_priority_adjust(struct pthread *, pthread_mutex_t); +static void mutex_rescan_owned (struct pthread *, struct pthread *, + struct pthread_mutex *); +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 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_lock, pthread_mutex_lock); +__weak_reference(__pthread_mutex_timedlock, pthread_mutex_timedlock); +__weak_reference(__pthread_mutex_trylock, pthread_mutex_trylock); + +/* 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_unlock, pthread_mutex_unlock); + + + +int +_pthread_mutex_init(pthread_mutex_t *mutex, + const pthread_mutexattr_t *mutex_attr) +{ + struct pthread_mutex *pmutex; + enum pthread_mutextype type; + int protocol; + int ceiling; + int flags; + int ret = 0; + + if (mutex == NULL) + ret = EINVAL; + + /* Check if default mutex attributes: */ + else if (mutex_attr == NULL || *mutex_attr == NULL) { + /* Default to a (error checking) POSIX mutex: */ + type = PTHREAD_MUTEX_ERRORCHECK; + protocol = PTHREAD_PRIO_NONE; + ceiling = THR_MAX_PRIORITY; + flags = 0; + } + + /* Check mutex type: */ + else if (((*mutex_attr)->m_type < PTHREAD_MUTEX_ERRORCHECK) || + ((*mutex_attr)->m_type >= MUTEX_TYPE_MAX)) + /* Return an invalid argument error: */ + ret = EINVAL; + + /* Check mutex protocol: */ + else if (((*mutex_attr)->m_protocol < PTHREAD_PRIO_NONE) || + ((*mutex_attr)->m_protocol > PTHREAD_MUTEX_RECURSIVE)) + /* Return an invalid argument error: */ + ret = EINVAL; + + else { + /* Use the requested mutex type and protocol: */ + type = (*mutex_attr)->m_type; + protocol = (*mutex_attr)->m_protocol; + ceiling = (*mutex_attr)->m_ceiling; + flags = (*mutex_attr)->m_flags; + } + + /* Check no errors so far: */ + if (ret == 0) { + if ((pmutex = (pthread_mutex_t) + malloc(sizeof(struct pthread_mutex))) == NULL) + ret = ENOMEM; + else if (_lock_init(&pmutex->m_lock, LCK_ADAPTIVE, + _thr_lock_wait, _thr_lock_wakeup) != 0) { + free(pmutex); + *mutex = NULL; + ret = ENOMEM; + } else { + /* Set the mutex flags: */ + pmutex->m_flags = flags; + + /* Process according to mutex type: */ + switch (type) { + /* case PTHREAD_MUTEX_DEFAULT: */ + case PTHREAD_MUTEX_ERRORCHECK: + case PTHREAD_MUTEX_NORMAL: + /* Nothing to do here. */ + break; + + /* Single UNIX Spec 2 recursive mutex: */ + case PTHREAD_MUTEX_RECURSIVE: + /* Reset the mutex count: */ + pmutex->m_count = 0; + break; + + /* Trap invalid mutex types: */ + default: + /* Return an invalid argument error: */ + ret = EINVAL; + break; + } + if (ret == 0) { + /* Initialise the rest of the mutex: */ + TAILQ_INIT(&pmutex->m_queue); + pmutex->m_flags |= MUTEX_FLAGS_INITED; + pmutex->m_owner = NULL; + pmutex->m_type = type; + pmutex->m_protocol = protocol; + pmutex->m_refcount = 0; + if (protocol == PTHREAD_PRIO_PROTECT) + pmutex->m_prio = ceiling; + else + pmutex->m_prio = -1; + pmutex->m_saved_prio = 0; + MUTEX_INIT_LINK(pmutex); + *mutex = pmutex; + } else { + /* Free the mutex lock structure: */ + MUTEX_DESTROY(pmutex); + *mutex = NULL; + } + } + } + /* Return the completion status: */ + return (ret); +} + +void +_thr_mutex_reinit(pthread_mutex_t *mutex) +{ + _lock_reinit(&(*mutex)->m_lock, LCK_ADAPTIVE, + _thr_lock_wait, _thr_lock_wakeup); + TAILQ_INIT(&(*mutex)->m_queue); + (*mutex)->m_owner = NULL; + (*mutex)->m_count = 0; + (*mutex)->m_refcount = 0; + (*mutex)->m_prio = 0; + (*mutex)->m_saved_prio = 0; +} + +int +_pthread_mutex_destroy(pthread_mutex_t *mutex) +{ + struct pthread *curthread = _get_curthread(); + pthread_mutex_t m; + int ret = 0; + + if (mutex == NULL || *mutex == NULL) + ret = EINVAL; + else { + /* Lock the mutex structure: */ + THR_LOCK_ACQUIRE(curthread, &(*mutex)->m_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)) { + ret = EBUSY; + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*mutex)->m_lock); + } else { + /* + * Save a pointer to the mutex so it can be free'd + * and set the caller's pointer to NULL: + */ + m = *mutex; + *mutex = NULL; + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &m->m_lock); + + /* + * Free the memory allocated for the mutex + * structure: + */ + MUTEX_ASSERT_NOT_OWNED(m); + MUTEX_DESTROY(m); + } + } + + /* Return the completion status: */ + return (ret); +} + +static int +init_static(struct pthread *thread, pthread_mutex_t *mutex) +{ + int ret; + + THR_LOCK_ACQUIRE(thread, &_mutex_static_lock); + + if (*mutex == NULL) + ret = pthread_mutex_init(mutex, NULL); + else + ret = 0; + + THR_LOCK_RELEASE(thread, &_mutex_static_lock); + + return (ret); +} + +static int +init_static_private(struct pthread *thread, pthread_mutex_t *mutex) +{ + int ret; + + THR_LOCK_ACQUIRE(thread, &_mutex_static_lock); + + if (*mutex == NULL) + ret = pthread_mutex_init(mutex, &static_mattr); + else + ret = 0; + + THR_LOCK_RELEASE(thread, &_mutex_static_lock); + + return (ret); +} + +static int +mutex_trylock_common(struct pthread *curthread, pthread_mutex_t *mutex) +{ + int ret = 0; + + THR_ASSERT((mutex != NULL) && (*mutex != NULL), + "Uninitialized mutex in pthread_mutex_trylock_basic"); + + /* Lock the mutex structure: */ + THR_LOCK_ACQUIRE(curthread, &(*mutex)->m_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_INIT_LINK(*mutex); + (*mutex)->m_flags |= MUTEX_FLAGS_INITED; + } + + /* Process according to mutex type: */ + switch ((*mutex)->m_protocol) { + /* Default POSIX mutex: */ + case PTHREAD_PRIO_NONE: + /* Check if this mutex is not locked: */ + if ((*mutex)->m_owner == NULL) { + /* Lock the mutex for the running thread: */ + (*mutex)->m_owner = curthread; + + /* Add to the list of owned mutexes: */ + MUTEX_ASSERT_NOT_OWNED(*mutex); + TAILQ_INSERT_TAIL(&curthread->mutexq, + (*mutex), m_qe); + } else if ((*mutex)->m_owner == curthread) + ret = mutex_self_trylock(curthread, *mutex); + else + /* Return a busy error: */ + ret = EBUSY; + break; + + /* POSIX priority inheritence mutex: */ + case PTHREAD_PRIO_INHERIT: + /* Check if this mutex is not locked: */ + if ((*mutex)->m_owner == NULL) { + /* Lock the mutex for the running thread: */ + (*mutex)->m_owner = curthread; + + THR_SCHED_LOCK(curthread, curthread); + /* Track number of priority mutexes owned: */ + curthread->priority_mutex_count++; + + /* + * The mutex takes on the attributes of the + * running thread when there are no waiters. + */ + (*mutex)->m_prio = curthread->active_priority; + (*mutex)->m_saved_prio = + curthread->inherited_priority; + curthread->inherited_priority = (*mutex)->m_prio; + THR_SCHED_UNLOCK(curthread, curthread); + + /* Add to the list of owned mutexes: */ + MUTEX_ASSERT_NOT_OWNED(*mutex); + TAILQ_INSERT_TAIL(&curthread->mutexq, + (*mutex), m_qe); + } else if ((*mutex)->m_owner == curthread) + ret = mutex_self_trylock(curthread, *mutex); + else + /* Return a busy error: */ + ret = EBUSY; + break; + + /* POSIX priority protection mutex: */ + case PTHREAD_PRIO_PROTECT: + /* Check for a priority ceiling violation: */ + if (curthread->active_priority > (*mutex)->m_prio) + ret = EINVAL; + + /* Check if this mutex is not locked: */ + else if ((*mutex)->m_owner == NULL) { + /* Lock the mutex for the running thread: */ + (*mutex)->m_owner = curthread; + + THR_SCHED_LOCK(curthread, curthread); + /* Track number of priority mutexes owned: */ + curthread->priority_mutex_count++; + + /* + * The running thread inherits the ceiling + * priority of the mutex and executes at that + * priority. + */ + curthread->active_priority = (*mutex)->m_prio; + (*mutex)->m_saved_prio = + curthread->inherited_priority; + curthread->inherited_priority = + (*mutex)->m_prio; + THR_SCHED_UNLOCK(curthread, curthread); + /* Add to the list of owned mutexes: */ + MUTEX_ASSERT_NOT_OWNED(*mutex); + TAILQ_INSERT_TAIL(&curthread->mutexq, + (*mutex), m_qe); + } else if ((*mutex)->m_owner == curthread) + ret = mutex_self_trylock(curthread, *mutex); + else + /* Return a busy error: */ + ret = EBUSY; + break; + + /* Trap invalid mutex types: */ + default: + /* Return an invalid argument error: */ + ret = EINVAL; + break; + } + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*mutex)->m_lock); + + /* Return the completion status: */ + return (ret); +} + +int +__pthread_mutex_trylock(pthread_mutex_t *mutex) +{ + struct pthread *curthread = _get_curthread(); + int ret = 0; + + if (mutex == NULL) + ret = EINVAL; + + /* + * If the mutex is statically initialized, perform the dynamic + * initialization: + */ + else if ((*mutex != NULL) || + ((ret = init_static(curthread, mutex)) == 0)) + ret = mutex_trylock_common(curthread, mutex); + + return (ret); +} + +int +_pthread_mutex_trylock(pthread_mutex_t *mutex) +{ + struct pthread *curthread = _get_curthread(); + int ret = 0; + + if (mutex == NULL) + ret = EINVAL; + + /* + * If the mutex is statically initialized, perform the dynamic + * initialization marking the mutex private (delete safe): + */ + else if ((*mutex != NULL) || + ((ret = init_static_private(curthread, mutex)) == 0)) + ret = mutex_trylock_common(curthread, mutex); + + return (ret); +} + +static int +mutex_lock_common(struct pthread *curthread, pthread_mutex_t *m, + const struct timespec * abstime) +{ + int ret = 0; + + THR_ASSERT((m != NULL) && (*m != NULL), + "Uninitialized mutex in pthread_mutex_trylock_basic"); + + if (abstime != NULL && (abstime->tv_sec < 0 || abstime->tv_nsec < 0 || + abstime->tv_nsec >= 1000000000)) + return (EINVAL); + + /* Reset the interrupted flag: */ + curthread->interrupted = 0; + curthread->timeout = 0; + curthread->wakeup_time.tv_sec = -1; + + /* + * Enter a loop waiting to become the mutex owner. We need a + * loop in case the waiting thread is interrupted by a signal + * to execute a signal handler. It is not (currently) possible + * to remain in the waiting queue while running a handler. + * Instead, the thread is interrupted and backed out of the + * waiting queue prior to executing the signal handler. + */ + do { + /* Lock the mutex structure: */ + THR_LOCK_ACQUIRE(curthread, &(*m)->m_lock); + + /* + * If the mutex was statically allocated, properly + * initialize the tail queue. + */ + if (((*m)->m_flags & MUTEX_FLAGS_INITED) == 0) { + TAILQ_INIT(&(*m)->m_queue); + (*m)->m_flags |= MUTEX_FLAGS_INITED; + MUTEX_INIT_LINK(*m); + } + + /* Process according to mutex type: */ + switch ((*m)->m_protocol) { + /* Default POSIX mutex: */ + case PTHREAD_PRIO_NONE: + if ((*m)->m_owner == NULL) { + /* Lock the mutex for this thread: */ + (*m)->m_owner = curthread; + + /* Add to the list of owned mutexes: */ + MUTEX_ASSERT_NOT_OWNED(*m); + TAILQ_INSERT_TAIL(&curthread->mutexq, + (*m), m_qe); + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + } else if ((*m)->m_owner == curthread) { + ret = mutex_self_lock(curthread, *m); + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + } else { + /* Set the wakeup time: */ + if (abstime) { + curthread->wakeup_time.tv_sec = + abstime->tv_sec; + curthread->wakeup_time.tv_nsec = + abstime->tv_nsec; + } + + /* + * Join the queue of threads waiting to lock + * the mutex and save a pointer to the mutex. + */ + mutex_queue_enq(*m, curthread); + curthread->data.mutex = *m; + /* + * This thread is active and is in a critical + * region (holding the mutex lock); we should + * be able to safely set the state. + */ + THR_SCHED_LOCK(curthread, curthread); + THR_SET_STATE(curthread, PS_MUTEX_WAIT); + THR_SCHED_UNLOCK(curthread, curthread); + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + + /* Schedule the next thread: */ + _thr_sched_switch(curthread); + + curthread->data.mutex = NULL; + if (THR_IN_MUTEXQ(curthread)) { + THR_LOCK_ACQUIRE(curthread, &(*m)->m_lock); + mutex_queue_remove(*m, curthread); + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + } + } + break; + + /* POSIX priority inheritence mutex: */ + case PTHREAD_PRIO_INHERIT: + /* Check if this mutex is not locked: */ + if ((*m)->m_owner == NULL) { + /* Lock the mutex for this thread: */ + (*m)->m_owner = curthread; + + THR_SCHED_LOCK(curthread, curthread); + /* Track number of priority mutexes owned: */ + curthread->priority_mutex_count++; + + /* + * The mutex takes on attributes of the + * running thread when there are no waiters. + * Make sure the thread's scheduling lock is + * held while priorities are adjusted. + */ + (*m)->m_prio = curthread->active_priority; + (*m)->m_saved_prio = + curthread->inherited_priority; + curthread->inherited_priority = (*m)->m_prio; + THR_SCHED_UNLOCK(curthread, curthread); + + /* Add to the list of owned mutexes: */ + MUTEX_ASSERT_NOT_OWNED(*m); + TAILQ_INSERT_TAIL(&curthread->mutexq, + (*m), m_qe); + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + } else if ((*m)->m_owner == curthread) { + ret = mutex_self_lock(curthread, *m); + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + } else { + /* Set the wakeup time: */ + if (abstime) { + curthread->wakeup_time.tv_sec = + abstime->tv_sec; + curthread->wakeup_time.tv_nsec = + abstime->tv_nsec; + } + + /* + * Join the queue of threads waiting to lock + * the mutex and save a pointer to the mutex. + */ + mutex_queue_enq(*m, curthread); + curthread->data.mutex = *m; + + /* + * This thread is active and is in a critical + * region (holding the mutex lock); we should + * be able to safely set the state. + */ + if (curthread->active_priority > (*m)->m_prio) + /* Adjust priorities: */ + mutex_priority_adjust(curthread, *m); + + THR_SCHED_LOCK(curthread, curthread); + THR_SET_STATE(curthread, PS_MUTEX_WAIT); + THR_SCHED_UNLOCK(curthread, curthread); + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + + /* Schedule the next thread: */ + _thr_sched_switch(curthread); + + curthread->data.mutex = NULL; + if (THR_IN_MUTEXQ(curthread)) { + THR_LOCK_ACQUIRE(curthread, &(*m)->m_lock); + mutex_queue_remove(*m, curthread); + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + } + } + break; + + /* POSIX priority protection mutex: */ + case PTHREAD_PRIO_PROTECT: + /* Check for a priority ceiling violation: */ + if (curthread->active_priority > (*m)->m_prio) { + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + ret = EINVAL; + } + /* Check if this mutex is not locked: */ + else if ((*m)->m_owner == NULL) { + /* + * Lock the mutex for the running + * thread: + */ + (*m)->m_owner = curthread; + + THR_SCHED_LOCK(curthread, curthread); + /* Track number of priority mutexes owned: */ + curthread->priority_mutex_count++; + + /* + * The running thread inherits the ceiling + * priority of the mutex and executes at that + * priority. Make sure the thread's + * scheduling lock is held while priorities + * are adjusted. + */ + curthread->active_priority = (*m)->m_prio; + (*m)->m_saved_prio = + curthread->inherited_priority; + curthread->inherited_priority = (*m)->m_prio; + THR_SCHED_UNLOCK(curthread, curthread); + + /* Add to the list of owned mutexes: */ + MUTEX_ASSERT_NOT_OWNED(*m); + TAILQ_INSERT_TAIL(&curthread->mutexq, + (*m), m_qe); + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + } else if ((*m)->m_owner == curthread) { + ret = mutex_self_lock(curthread, *m); + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + } else { + /* Set the wakeup time: */ + if (abstime) { + curthread->wakeup_time.tv_sec = + abstime->tv_sec; + curthread->wakeup_time.tv_nsec = + abstime->tv_nsec; + } + + /* + * Join the queue of threads waiting to lock + * the mutex and save a pointer to the mutex. + */ + mutex_queue_enq(*m, curthread); + curthread->data.mutex = *m; + + /* Clear any previous error: */ + curthread->error = 0; + + /* + * This thread is active and is in a critical + * region (holding the mutex lock); we should + * be able to safely set the state. + */ + + THR_SCHED_LOCK(curthread, curthread); + THR_SET_STATE(curthread, PS_MUTEX_WAIT); + THR_SCHED_UNLOCK(curthread, curthread); + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + + /* Schedule the next thread: */ + _thr_sched_switch(curthread); + + curthread->data.mutex = NULL; + if (THR_IN_MUTEXQ(curthread)) { + THR_LOCK_ACQUIRE(curthread, &(*m)->m_lock); + mutex_queue_remove(*m, curthread); + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + } + + /* + * The threads priority may have changed while + * waiting for the mutex causing a ceiling + * violation. + */ + ret = curthread->error; + curthread->error = 0; + } + break; + + /* Trap invalid mutex types: */ + default: + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + + /* Return an invalid argument error: */ + ret = EINVAL; + break; + } + + } while (((*m)->m_owner != curthread) && (ret == 0) && + (curthread->interrupted == 0) && (curthread->timeout == 0)); + + if (ret == 0 && (*m)->m_owner != curthread && curthread->timeout) + ret = ETIMEDOUT; + + /* + * Check to see if this thread was interrupted and + * is still in the mutex queue of waiting threads: + */ + if (curthread->interrupted != 0) { + /* Remove this thread from the mutex queue. */ + THR_LOCK_ACQUIRE(curthread, &(*m)->m_lock); + if (THR_IN_SYNCQ(curthread)) + mutex_queue_remove(*m, curthread); + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + + /* Check for asynchronous cancellation. */ + if (curthread->continuation != NULL) + curthread->continuation((void *) curthread); + } + + /* Return the completion status: */ + return (ret); +} + +int +__pthread_mutex_lock(pthread_mutex_t *m) +{ + struct pthread *curthread; + int ret = 0; + + if (_thr_initial == NULL) + _libpthread_init(NULL); + + curthread = _get_curthread(); + if (m == NULL) + ret = EINVAL; + + /* + * If the mutex is statically initialized, perform the dynamic + * initialization: + */ + else if ((*m != NULL) || ((ret = init_static(curthread, m)) == 0)) + ret = mutex_lock_common(curthread, m, NULL); + + return (ret); +} + +__strong_reference(__pthread_mutex_lock, _thr_mutex_lock); + +int +_pthread_mutex_lock(pthread_mutex_t *m) +{ + struct pthread *curthread; + int ret = 0; + + if (_thr_initial == NULL) + _libpthread_init(NULL); + curthread = _get_curthread(); + + if (m == NULL) + ret = EINVAL; + + /* + * If the mutex is statically initialized, perform the dynamic + * initialization marking it private (delete safe): + */ + else if ((*m != NULL) || + ((ret = init_static_private(curthread, m)) == 0)) + ret = mutex_lock_common(curthread, m, NULL); + + return (ret); +} + +int +__pthread_mutex_timedlock(pthread_mutex_t *m, + const struct timespec *abs_timeout) +{ + struct pthread *curthread; + int ret = 0; + + if (_thr_initial == NULL) + _libpthread_init(NULL); + + curthread = _get_curthread(); + if (m == NULL) + ret = EINVAL; + + /* + * If the mutex is statically initialized, perform the dynamic + * initialization: + */ + else if ((*m != NULL) || ((ret = init_static(curthread, m)) == 0)) + ret = mutex_lock_common(curthread, m, abs_timeout); + + return (ret); +} + +int +_pthread_mutex_timedlock(pthread_mutex_t *m, + const struct timespec *abs_timeout) +{ + struct pthread *curthread; + int ret = 0; + + if (_thr_initial == NULL) + _libpthread_init(NULL); + curthread = _get_curthread(); + + if (m == NULL) + ret = EINVAL; + + /* + * If the mutex is statically initialized, perform the dynamic + * initialization marking it private (delete safe): + */ + else if ((*m != NULL) || + ((ret = init_static_private(curthread, m)) == 0)) + ret = mutex_lock_common(curthread, m, abs_timeout); + + return (ret); +} + +int +_pthread_mutex_unlock(pthread_mutex_t *m) +{ + return (mutex_unlock_common(m, /* add reference */ 0)); +} + +__strong_reference(_pthread_mutex_unlock, _thr_mutex_unlock); + +int +_mutex_cv_unlock(pthread_mutex_t *m) +{ + return (mutex_unlock_common(m, /* add reference */ 1)); +} + +int +_mutex_cv_lock(pthread_mutex_t *m) +{ + struct pthread *curthread; + int ret; + + curthread = _get_curthread(); + if ((ret = _pthread_mutex_lock(m)) == 0) { + THR_LOCK_ACQUIRE(curthread, &(*m)->m_lock); + (*m)->m_refcount--; + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + } + return (ret); +} + +static inline int +mutex_self_trylock(struct pthread *curthread, pthread_mutex_t m) +{ + int ret = 0; + + switch (m->m_type) { + /* case PTHREAD_MUTEX_DEFAULT: */ + case PTHREAD_MUTEX_ERRORCHECK: + case PTHREAD_MUTEX_NORMAL: + /* + * POSIX specifies that mutexes should return EDEADLK if a + * recursive lock is detected. + */ + if (m->m_owner == curthread) + ret = EDEADLK; + else + ret = EBUSY; + break; + + case PTHREAD_MUTEX_RECURSIVE: + /* Increment the lock count: */ + m->m_count++; + break; + + default: + /* Trap invalid mutex types; */ + ret = EINVAL; + } + + return (ret); +} + +static inline int +mutex_self_lock(struct pthread *curthread, pthread_mutex_t m) +{ + int ret = 0; + + switch (m->m_type) { + /* case PTHREAD_MUTEX_DEFAULT: */ + case PTHREAD_MUTEX_ERRORCHECK: + /* + * POSIX specifies that mutexes should return EDEADLK if a + * recursive lock is detected. + */ + ret = EDEADLK; + break; + + case PTHREAD_MUTEX_NORMAL: + /* + * What SS2 define as a 'normal' mutex. Intentionally + * deadlock on attempts to get a lock you already own. + */ + + THR_SCHED_LOCK(curthread, curthread); + THR_SET_STATE(curthread, PS_DEADLOCK); + THR_SCHED_UNLOCK(curthread, curthread); + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &m->m_lock); + + /* Schedule the next thread: */ + _thr_sched_switch(curthread); + break; + + case PTHREAD_MUTEX_RECURSIVE: + /* Increment the lock count: */ + m->m_count++; + break; + + default: + /* Trap invalid mutex types; */ + ret = EINVAL; + } + + return (ret); +} + +static int +mutex_unlock_common(pthread_mutex_t *m, int add_reference) +{ + struct pthread *curthread = _get_curthread(); + struct kse_mailbox *kmbx = NULL; + int ret = 0; + + if (m == NULL || *m == NULL) + ret = EINVAL; + else { + /* Lock the mutex structure: */ + THR_LOCK_ACQUIRE(curthread, &(*m)->m_lock); + + /* Process according to mutex type: */ + switch ((*m)->m_protocol) { + /* Default POSIX mutex: */ + case PTHREAD_PRIO_NONE: + /* + * Check if the running thread is not the owner of the + * mutex: + */ + if ((*m)->m_owner != curthread) + ret = EPERM; + else if (((*m)->m_type == PTHREAD_MUTEX_RECURSIVE) && + ((*m)->m_count > 0)) + /* Decrement the count: */ + (*m)->m_count--; + else { + /* + * Clear the count in case this is a recursive + * mutex. + */ + (*m)->m_count = 0; + + /* Remove the mutex from the threads queue. */ + MUTEX_ASSERT_IS_OWNED(*m); + TAILQ_REMOVE(&(*m)->m_owner->mutexq, + (*m), m_qe); + MUTEX_INIT_LINK(*m); + + /* + * Hand off the mutex to the next waiting + * thread: + */ + kmbx = mutex_handoff(curthread, *m); + } + break; + + /* POSIX priority inheritence mutex: */ + case PTHREAD_PRIO_INHERIT: + /* + * Check if the running thread is not the owner of the + * mutex: + */ + if ((*m)->m_owner != curthread) + ret = EPERM; + else if (((*m)->m_type == PTHREAD_MUTEX_RECURSIVE) && + ((*m)->m_count > 0)) + /* Decrement the count: */ + (*m)->m_count--; + else { + /* + * Clear the count in case this is recursive + * mutex. + */ + (*m)->m_count = 0; + + /* + * Restore the threads inherited priority and + * recompute the active priority (being careful + * not to override changes in the threads base + * priority subsequent to locking the mutex). + */ + THR_SCHED_LOCK(curthread, curthread); + curthread->inherited_priority = + (*m)->m_saved_prio; + curthread->active_priority = + MAX(curthread->inherited_priority, + curthread->base_priority); + + /* + * This thread now owns one less priority mutex. + */ + curthread->priority_mutex_count--; + THR_SCHED_UNLOCK(curthread, curthread); + + /* Remove the mutex from the threads queue. */ + MUTEX_ASSERT_IS_OWNED(*m); + TAILQ_REMOVE(&(*m)->m_owner->mutexq, + (*m), m_qe); + MUTEX_INIT_LINK(*m); + + /* + * Hand off the mutex to the next waiting + * thread: + */ + kmbx = mutex_handoff(curthread, *m); + } + break; + + /* POSIX priority ceiling mutex: */ + case PTHREAD_PRIO_PROTECT: + /* + * Check if the running thread is not the owner of the + * mutex: + */ + if ((*m)->m_owner != curthread) + ret = EPERM; + else if (((*m)->m_type == PTHREAD_MUTEX_RECURSIVE) && + ((*m)->m_count > 0)) + /* Decrement the count: */ + (*m)->m_count--; + else { + /* + * Clear the count in case this is a recursive + * mutex. + */ + (*m)->m_count = 0; + + /* + * Restore the threads inherited priority and + * recompute the active priority (being careful + * not to override changes in the threads base + * priority subsequent to locking the mutex). + */ + THR_SCHED_LOCK(curthread, curthread); + curthread->inherited_priority = + (*m)->m_saved_prio; + curthread->active_priority = + MAX(curthread->inherited_priority, + curthread->base_priority); + + /* + * This thread now owns one less priority mutex. + */ + curthread->priority_mutex_count--; + THR_SCHED_UNLOCK(curthread, curthread); + + /* Remove the mutex from the threads queue. */ + MUTEX_ASSERT_IS_OWNED(*m); + TAILQ_REMOVE(&(*m)->m_owner->mutexq, + (*m), m_qe); + MUTEX_INIT_LINK(*m); + + /* + * Hand off the mutex to the next waiting + * thread: + */ + kmbx = mutex_handoff(curthread, *m); + } + break; + + /* Trap invalid mutex types: */ + default: + /* Return an invalid argument error: */ + ret = EINVAL; + break; + } + + if ((ret == 0) && (add_reference != 0)) + /* Increment the reference count: */ + (*m)->m_refcount++; + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &(*m)->m_lock); + if (kmbx != NULL) + kse_wakeup(kmbx); + } + + /* Return the completion status: */ + return (ret); +} + + +/* + * This function is called when a change in base priority occurs for + * a thread that is holding or waiting for a priority protection or + * inheritence mutex. A change in a threads base priority can effect + * changes to active priorities of other threads and to the ordering + * of mutex locking by waiting threads. + * + * This must be called without the target thread's scheduling lock held. + */ +void +_mutex_notify_priochange(struct pthread *curthread, struct pthread *pthread, + int propagate_prio) +{ + struct pthread_mutex *m; + + /* Adjust the priorites of any owned priority mutexes: */ + if (pthread->priority_mutex_count > 0) { + /* + * Rescan the mutexes owned by this thread and correct + * their priorities to account for this threads change + * in priority. This has the side effect of changing + * the threads active priority. + * + * Be sure to lock the first mutex in the list of owned + * mutexes. This acts as a barrier against another + * simultaneous call to change the threads priority + * and from the owning thread releasing the mutex. + */ + m = TAILQ_FIRST(&pthread->mutexq); + if (m != NULL) { + THR_LOCK_ACQUIRE(curthread, &m->m_lock); + /* + * Make sure the thread still owns the lock. + */ + if (m == TAILQ_FIRST(&pthread->mutexq)) + mutex_rescan_owned(curthread, pthread, + /* rescan all owned */ NULL); + THR_LOCK_RELEASE(curthread, &m->m_lock); + } + } + + /* + * If this thread is waiting on a priority inheritence mutex, + * check for priority adjustments. A change in priority can + * also cause a ceiling violation(*) for a thread waiting on + * a priority protection mutex; we don't perform the check here + * as it is done in pthread_mutex_unlock. + * + * (*) It should be noted that a priority change to a thread + * _after_ taking and owning a priority ceiling mutex + * does not affect ownership of that mutex; the ceiling + * priority is only checked before mutex ownership occurs. + */ + if (propagate_prio != 0) { + /* + * Lock the thread's scheduling queue. This is a bit + * convoluted; the "in synchronization queue flag" can + * only be cleared with both the thread's scheduling and + * mutex locks held. The thread's pointer to the wanted + * mutex is guaranteed to be valid during this time. + */ + THR_SCHED_LOCK(curthread, pthread); + + if (((pthread->sflags & THR_FLAGS_IN_SYNCQ) == 0) || + ((m = pthread->data.mutex) == NULL)) + THR_SCHED_UNLOCK(curthread, pthread); + else { + /* + * This thread is currently waiting on a mutex; unlock + * the scheduling queue lock and lock the mutex. We + * can't hold both at the same time because the locking + * order could cause a deadlock. + */ + THR_SCHED_UNLOCK(curthread, pthread); + THR_LOCK_ACQUIRE(curthread, &m->m_lock); + + /* + * Check to make sure this thread is still in the + * same state (the lock above can yield the CPU to + * another thread or the thread may be running on + * another CPU). + */ + if (((pthread->sflags & THR_FLAGS_IN_SYNCQ) != 0) && + (pthread->data.mutex == m)) { + /* + * Remove and reinsert this thread into + * the list of waiting threads to preserve + * decreasing priority order. + */ + mutex_queue_remove(m, pthread); + mutex_queue_enq(m, pthread); + + if (m->m_protocol == PTHREAD_PRIO_INHERIT) + /* Adjust priorities: */ + mutex_priority_adjust(curthread, m); + } + + /* Unlock the mutex structure: */ + THR_LOCK_RELEASE(curthread, &m->m_lock); + } + } +} + +/* + * Called when a new thread is added to the mutex waiting queue or + * when a threads priority changes that is already in the mutex + * waiting queue. + * + * This must be called with the mutex locked by the current thread. + */ +static void +mutex_priority_adjust(struct pthread *curthread, pthread_mutex_t mutex) +{ + pthread_mutex_t m = mutex; + struct pthread *pthread_next, *pthread = mutex->m_owner; + int done, temp_prio; + + /* + * Calculate the mutex priority as the maximum of the highest + * active priority of any waiting threads and the owning threads + * active priority(*). + * + * (*) Because the owning threads current active priority may + * reflect priority inherited from this mutex (and the mutex + * priority may have changed) we must recalculate the active + * priority based on the threads saved inherited priority + * and its base priority. + */ + pthread_next = TAILQ_FIRST(&m->m_queue); /* should never be NULL */ + temp_prio = MAX(pthread_next->active_priority, + MAX(m->m_saved_prio, pthread->base_priority)); + + /* See if this mutex really needs adjusting: */ + if (temp_prio == m->m_prio) + /* No need to propagate the priority: */ + return; + + /* Set new priority of the mutex: */ + m->m_prio = temp_prio; + + /* + * Don't unlock the mutex passed in as an argument. It is + * expected to be locked and unlocked by the caller. + */ + done = 1; + do { + /* + * Save the threads priority before rescanning the + * owned mutexes: + */ + temp_prio = pthread->active_priority; + + /* + * Fix the priorities for all mutexes held by the owning + * thread since taking this mutex. This also has a + * potential side-effect of changing the threads priority. + * + * At this point the mutex is locked by the current thread. + * The owning thread can't release the mutex until it is + * unlocked, so we should be able to safely walk its list + * of owned mutexes. + */ + mutex_rescan_owned(curthread, pthread, m); + + /* + * If this isn't the first time through the loop, + * the current mutex needs to be unlocked. + */ + if (done == 0) + THR_LOCK_RELEASE(curthread, &m->m_lock); + + /* Assume we're done unless told otherwise: */ + done = 1; + + /* + * If the thread is currently waiting on a mutex, check + * to see if the threads new priority has affected the + * priority of the mutex. + */ + if ((temp_prio != pthread->active_priority) && + ((pthread->sflags & THR_FLAGS_IN_SYNCQ) != 0) && + ((m = pthread->data.mutex) != NULL) && + (m->m_protocol == PTHREAD_PRIO_INHERIT)) { + /* Lock the mutex structure: */ + THR_LOCK_ACQUIRE(curthread, &m->m_lock); + + /* + * Make sure the thread is still waiting on the + * mutex: + */ + if (((pthread->sflags & THR_FLAGS_IN_SYNCQ) != 0) && + (m == pthread->data.mutex)) { + /* + * The priority for this thread has changed. + * Remove and reinsert this thread into the + * list of waiting threads to preserve + * decreasing priority order. + */ + mutex_queue_remove(m, pthread); + mutex_queue_enq(m, pthread); + + /* + * Grab the waiting thread with highest + * priority: + */ + pthread_next = TAILQ_FIRST(&m->m_queue); + + /* + * Calculate the mutex priority as the maximum + * of the highest active priority of any + * waiting threads and the owning threads + * active priority. + */ + temp_prio = MAX(pthread_next->active_priority, + MAX(m->m_saved_prio, + m->m_owner->base_priority)); + + if (temp_prio != m->m_prio) { + /* + * The priority needs to be propagated + * to the mutex this thread is waiting + * on and up to the owner of that mutex. + */ + m->m_prio = temp_prio; + pthread = m->m_owner; + + /* We're not done yet: */ + done = 0; + } + } + /* Only release the mutex if we're done: */ + if (done != 0) + THR_LOCK_RELEASE(curthread, &m->m_lock); + } + } while (done == 0); +} + +static void +mutex_rescan_owned(struct pthread *curthread, struct pthread *pthread, + struct pthread_mutex *mutex) +{ + struct pthread_mutex *m; + struct pthread *pthread_next; + int active_prio, inherited_prio; + + /* + * Start walking the mutexes the thread has taken since + * taking this mutex. + */ + if (mutex == NULL) { + /* + * A null mutex means start at the beginning of the owned + * mutex list. + */ + m = TAILQ_FIRST(&pthread->mutexq); + + /* There is no inherited priority yet. */ + inherited_prio = 0; + } else { + /* + * The caller wants to start after a specific mutex. It + * is assumed that this mutex is a priority inheritence + * mutex and that its priority has been correctly + * calculated. + */ + m = TAILQ_NEXT(mutex, m_qe); + + /* Start inheriting priority from the specified mutex. */ + inherited_prio = mutex->m_prio; + } + active_prio = MAX(inherited_prio, pthread->base_priority); + + for (; m != NULL; m = TAILQ_NEXT(m, m_qe)) { + /* + * We only want to deal with priority inheritence + * mutexes. This might be optimized by only placing + * priority inheritence mutexes into the owned mutex + * list, but it may prove to be useful having all + * owned mutexes in this list. Consider a thread + * exiting while holding mutexes... + */ + if (m->m_protocol == PTHREAD_PRIO_INHERIT) { + /* + * Fix the owners saved (inherited) priority to + * reflect the priority of the previous mutex. + */ + m->m_saved_prio = inherited_prio; + + if ((pthread_next = TAILQ_FIRST(&m->m_queue)) != NULL) + /* Recalculate the priority of the mutex: */ + m->m_prio = MAX(active_prio, + pthread_next->active_priority); + else + m->m_prio = active_prio; + + /* Recalculate new inherited and active priorities: */ + inherited_prio = m->m_prio; + active_prio = MAX(m->m_prio, pthread->base_priority); + } + } + + /* + * Fix the threads inherited priority and recalculate its + * active priority. + */ + pthread->inherited_priority = inherited_prio; + active_prio = MAX(inherited_prio, pthread->base_priority); + + if (active_prio != pthread->active_priority) { + /* Lock the thread's scheduling queue: */ + THR_SCHED_LOCK(curthread, pthread); + + if ((pthread->flags & THR_FLAGS_IN_RUNQ) == 0) { + /* + * This thread is not in a run queue. Just set + * its active priority. + */ + pthread->active_priority = active_prio; + } + else { + /* + * This thread is in a run queue. Remove it from + * the queue before changing its priority: + */ + THR_RUNQ_REMOVE(pthread); + + /* + * POSIX states that if the priority is being + * lowered, the thread must be inserted at the + * head of the queue for its priority if it owns + * any priority protection or inheritence mutexes. + */ + if ((active_prio < pthread->active_priority) && + (pthread->priority_mutex_count > 0)) { + /* Set the new active priority. */ + pthread->active_priority = active_prio; + + THR_RUNQ_INSERT_HEAD(pthread); + } else { + /* Set the new active priority. */ + pthread->active_priority = active_prio; + + THR_RUNQ_INSERT_TAIL(pthread); + } + } + THR_SCHED_UNLOCK(curthread, pthread); + } +} + +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); + } +} + +/* + * This is called by the current thread when it wants to back out of a + * mutex_lock in order to run a signal handler. + */ +void +_mutex_lock_backout(struct pthread *curthread) +{ + struct pthread_mutex *m; + + if ((curthread->sflags & THR_FLAGS_IN_SYNCQ) != 0) { + /* + * Any other thread may clear the "in sync queue flag", + * but only the current thread can clear the pointer + * to the mutex. So if the flag is set, we can + * guarantee that the pointer to the mutex is valid. + * The only problem may be if the mutex is destroyed + * out from under us, but that should be considered + * an application bug. + */ + m = curthread->data.mutex; + + /* Lock the mutex structure: */ + THR_LOCK_ACQUIRE(curthread, &m->m_lock); + + + /* + * Check to make sure this thread doesn't already own + * the mutex. Since mutexes are unlocked with direct + * handoffs, it is possible the previous owner gave it + * to us after we checked the sync queue flag and before + * we locked the mutex structure. + */ + if (m->m_owner == curthread) { + THR_LOCK_RELEASE(curthread, &m->m_lock); + mutex_unlock_common(&m, /* add_reference */ 0); + } else { + /* + * Remove ourselves from the mutex queue and + * clear the pointer to the mutex. We may no + * longer be in the mutex queue, but the removal + * function will DTRT. + */ + mutex_queue_remove(m, curthread); + curthread->data.mutex = NULL; + THR_LOCK_RELEASE(curthread, &m->m_lock); + } + } +} + +/* + * Dequeue a waiting thread from the head of a mutex queue in descending + * priority order. + * + * In order to properly dequeue a thread from the mutex queue and + * make it runnable without the possibility of errant wakeups, it + * is necessary to lock the thread's scheduling queue while also + * holding the mutex lock. + */ +static struct kse_mailbox * +mutex_handoff(struct pthread *curthread, struct pthread_mutex *mutex) +{ + struct kse_mailbox *kmbx = NULL; + struct pthread *pthread; + + /* Keep dequeueing until we find a valid thread: */ + mutex->m_owner = NULL; + pthread = TAILQ_FIRST(&mutex->m_queue); + while (pthread != NULL) { + /* Take the thread's scheduling lock: */ + THR_SCHED_LOCK(curthread, pthread); + + /* Remove the thread from the mutex queue: */ + TAILQ_REMOVE(&mutex->m_queue, pthread, sqe); + pthread->sflags &= ~THR_FLAGS_IN_SYNCQ; + + /* + * Only exit the loop if the thread hasn't been + * cancelled. + */ + switch (mutex->m_protocol) { + case PTHREAD_PRIO_NONE: + /* + * Assign the new owner and add the mutex to the + * thread's list of owned mutexes. + */ + mutex->m_owner = pthread; + TAILQ_INSERT_TAIL(&pthread->mutexq, mutex, m_qe); + break; + + case PTHREAD_PRIO_INHERIT: + /* + * Assign the new owner and add the mutex to the + * thread's list of owned mutexes. + */ + mutex->m_owner = pthread; + TAILQ_INSERT_TAIL(&pthread->mutexq, mutex, m_qe); + + /* Track number of priority mutexes owned: */ + pthread->priority_mutex_count++; + + /* + * Set the priority of the mutex. Since our waiting + * threads are in descending priority order, the + * priority of the mutex becomes the active priority + * of the thread we just dequeued. + */ + mutex->m_prio = pthread->active_priority; + + /* Save the owning threads inherited priority: */ + mutex->m_saved_prio = pthread->inherited_priority; + + /* + * The owning threads inherited priority now becomes + * his active priority (the priority of the mutex). + */ + pthread->inherited_priority = mutex->m_prio; + break; + + case PTHREAD_PRIO_PROTECT: + if (pthread->active_priority > mutex->m_prio) { + /* + * Either the mutex ceiling priority has + * been lowered and/or this threads priority + * has been raised subsequent to the thread + * being queued on the waiting list. + */ + pthread->error = EINVAL; + } + else { + /* + * Assign the new owner and add the mutex + * to the thread's list of owned mutexes. + */ + mutex->m_owner = pthread; + TAILQ_INSERT_TAIL(&pthread->mutexq, + mutex, m_qe); + + /* Track number of priority mutexes owned: */ + pthread->priority_mutex_count++; + + /* + * Save the owning threads inherited + * priority: + */ + mutex->m_saved_prio = + pthread->inherited_priority; + + /* + * The owning thread inherits the ceiling + * priority of the mutex and executes at + * that priority: + */ + pthread->inherited_priority = mutex->m_prio; + pthread->active_priority = mutex->m_prio; + + } + break; + } + + /* Make the thread runnable and unlock the scheduling queue: */ + kmbx = _thr_setrunnable_unlocked(pthread); + + /* Add a preemption point. */ + if ((curthread->kseg == pthread->kseg) && + (pthread->active_priority > curthread->active_priority)) + curthread->critical_yield = 1; + + THR_SCHED_UNLOCK(curthread, pthread); + if (mutex->m_owner == pthread) + /* We're done; a valid owner was found. */ + break; + else + /* Get the next thread from the waiting queue: */ + pthread = TAILQ_NEXT(pthread, sqe); + } + + if ((pthread == NULL) && (mutex->m_protocol == PTHREAD_PRIO_INHERIT)) + /* This mutex has no priority: */ + mutex->m_prio = 0; + return (kmbx); +} + +/* + * Dequeue a waiting thread from the head of a mutex queue in descending + * priority order. + */ +static inline pthread_t +mutex_queue_deq(struct pthread_mutex *mutex) +{ + pthread_t pthread; + + while ((pthread = TAILQ_FIRST(&mutex->m_queue)) != NULL) { + TAILQ_REMOVE(&mutex->m_queue, pthread, sqe); + pthread->sflags &= ~THR_FLAGS_IN_SYNCQ; + + /* + * Only exit the loop if the thread hasn't been + * cancelled. + */ + if (pthread->interrupted == 0) + 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->sflags & THR_FLAGS_IN_SYNCQ) != 0) { + TAILQ_REMOVE(&mutex->m_queue, pthread, sqe); + pthread->sflags &= ~THR_FLAGS_IN_SYNCQ; + } +} + +/* + * 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); + + THR_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); + } + pthread->sflags |= THR_FLAGS_IN_SYNCQ; +} |
