b5a8a15c2f
file descriptors needing to be polled (Doh!). Reported
by Dan Nelson <dnelson@emsphone.com>.
Don't install and start the scheduling timer until the
first thread is created. This prevents the overhead of
having a periodic scheduling signal in a single threaded
program. Reported by Dan Nelson <dnelson@emsphone.com>.
Allow builtin longjmps out of application installed
signal handlers without the need perform any post-handler
cleanup:
o Change signal handling to save the threads interrupted
context on the stack. The threads current context is
now always stored in the same place (in the pthread).
If and when a signal handler returns, the interrupted
context is copied back to the storage area in the pthread.
o Before calling invoking a signal handler for a thread,
back the thread out of any internal waiting queues
(mutex, CV, join, etc) to which it belongs.
Rework uthread_info.c a bit to make it easier to change
the format of a thread dump.
Use an alternal signal stack for the thread library's
signal handler. This allows us to fiddle with the main
threads stack without fear of it being in use.
Reviewed by: jasone
1481 lines
38 KiB
C
1481 lines
38 KiB
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.
|
|
*
|
|
* $FreeBSD$
|
|
*/
|
|
#include <stdlib.h>
|
|
#include <errno.h>
|
|
#include <string.h>
|
|
#include <sys/param.h>
|
|
#include <sys/queue.h>
|
|
#ifdef _THREAD_SAFE
|
|
#include <pthread.h>
|
|
#include "pthread_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"); \
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|
} while (0)
|
|
#else
|
|
#define _MUTEX_INIT_LINK(m)
|
|
#define _MUTEX_ASSERT_IS_OWNED(m)
|
|
#define _MUTEX_ASSERT_NOT_OWNED(m)
|
|
#endif
|
|
|
|
/*
|
|
* Prototypes
|
|
*/
|
|
static inline int mutex_self_trylock(pthread_mutex_t);
|
|
static inline int mutex_self_lock(pthread_mutex_t);
|
|
static inline int mutex_unlock_common(pthread_mutex_t *, int);
|
|
static void mutex_priority_adjust(pthread_mutex_t);
|
|
static void mutex_rescan_owned (pthread_t, pthread_mutex_t);
|
|
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 spinlock_t static_init_lock = _SPINLOCK_INITIALIZER;
|
|
|
|
/* Reinitialize a mutex to defaults. */
|
|
int
|
|
_mutex_reinit(pthread_mutex_t * mutex)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (mutex == NULL)
|
|
ret = EINVAL;
|
|
else if (*mutex == NULL)
|
|
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_PRIVATE;
|
|
(*mutex)->m_flags |= MUTEX_FLAGS_INITED;
|
|
(*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)
|
|
{
|
|
enum pthread_mutextype type;
|
|
int protocol;
|
|
int ceiling;
|
|
pthread_mutex_t pmutex;
|
|
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;
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|
protocol = PTHREAD_PRIO_NONE;
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|
ceiling = PTHREAD_MAX_PRIORITY;
|
|
}
|
|
|
|
/* Check mutex type: */
|
|
else if (((*mutex_attr)->m_type < PTHREAD_MUTEX_ERRORCHECK) ||
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|
((*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) ||
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|
((*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;
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|
protocol = (*mutex_attr)->m_protocol;
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|
ceiling = (*mutex_attr)->m_ceiling;
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|
}
|
|
|
|
/* Check no errors so far: */
|
|
if (ret == 0) {
|
|
if ((pmutex = (pthread_mutex_t)
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|
malloc(sizeof(struct pthread_mutex))) == NULL)
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|
ret = ENOMEM;
|
|
else {
|
|
/* Reset the mutex flags: */
|
|
pmutex->m_flags = 0;
|
|
|
|
/* Process according to mutex type: */
|
|
switch (type) {
|
|
/* case PTHREAD_MUTEX_DEFAULT: */
|
|
case PTHREAD_MUTEX_ERRORCHECK:
|
|
case PTHREAD_MUTEX_NORMAL:
|
|
/* Nothing to do here. */
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|
break;
|
|
|
|
/* Single UNIX Spec 2 recursive mutex: */
|
|
case PTHREAD_MUTEX_RECURSIVE:
|
|
/* Reset the mutex count: */
|
|
pmutex->m_data.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
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|
pmutex->m_prio = 0;
|
|
pmutex->m_saved_prio = 0;
|
|
_MUTEX_INIT_LINK(pmutex);
|
|
memset(&pmutex->lock, 0, sizeof(pmutex->lock));
|
|
*mutex = pmutex;
|
|
} else {
|
|
free(pmutex);
|
|
*mutex = NULL;
|
|
}
|
|
}
|
|
}
|
|
/* Return the completion status: */
|
|
return(ret);
|
|
}
|
|
|
|
int
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|
pthread_mutex_destroy(pthread_mutex_t * mutex)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (mutex == NULL || *mutex == NULL)
|
|
ret = EINVAL;
|
|
else {
|
|
/* 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)) {
|
|
ret = EBUSY;
|
|
|
|
/* Unlock the mutex structure: */
|
|
_SPINUNLOCK(&(*mutex)->lock);
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|
}
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|
else {
|
|
/*
|
|
* Free the memory allocated for the mutex
|
|
* structure:
|
|
*/
|
|
_MUTEX_ASSERT_NOT_OWNED(*mutex);
|
|
free(*mutex);
|
|
|
|
/*
|
|
* Leave the caller's pointer NULL now that
|
|
* the mutex has been destroyed:
|
|
*/
|
|
*mutex = NULL;
|
|
}
|
|
}
|
|
|
|
/* Return the completion status: */
|
|
return (ret);
|
|
}
|
|
|
|
static int
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|
init_static(pthread_mutex_t *mutex)
|
|
{
|
|
int ret;
|
|
|
|
_SPINLOCK(&static_init_lock);
|
|
|
|
if (*mutex == NULL)
|
|
ret = pthread_mutex_init(mutex, NULL);
|
|
else
|
|
ret = 0;
|
|
|
|
_SPINUNLOCK(&static_init_lock);
|
|
|
|
return(ret);
|
|
}
|
|
|
|
int
|
|
pthread_mutex_trylock(pthread_mutex_t * mutex)
|
|
{
|
|
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(mutex)) == 0) {
|
|
/*
|
|
* Defer signals to protect the scheduling queues from
|
|
* access by the signal handler:
|
|
*/
|
|
_thread_kern_sig_defer();
|
|
|
|
/* Lock the mutex structure: */
|
|
_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_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 = _thread_run;
|
|
|
|
/* Add to the list of owned mutexes: */
|
|
_MUTEX_ASSERT_NOT_OWNED(*mutex);
|
|
TAILQ_INSERT_TAIL(&_thread_run->mutexq,
|
|
(*mutex), m_qe);
|
|
} else if ((*mutex)->m_owner == _thread_run)
|
|
ret = mutex_self_trylock(*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 = _thread_run;
|
|
|
|
/* Track number of priority mutexes owned: */
|
|
_thread_run->priority_mutex_count++;
|
|
|
|
/*
|
|
* The mutex takes on the attributes of the
|
|
* running thread when there are no waiters.
|
|
*/
|
|
(*mutex)->m_prio = _thread_run->active_priority;
|
|
(*mutex)->m_saved_prio =
|
|
_thread_run->inherited_priority;
|
|
|
|
/* Add to the list of owned mutexes: */
|
|
_MUTEX_ASSERT_NOT_OWNED(*mutex);
|
|
TAILQ_INSERT_TAIL(&_thread_run->mutexq,
|
|
(*mutex), m_qe);
|
|
} else if ((*mutex)->m_owner == _thread_run)
|
|
ret = mutex_self_trylock(*mutex);
|
|
else
|
|
/* Return a busy error: */
|
|
ret = EBUSY;
|
|
break;
|
|
|
|
/* POSIX priority protection mutex: */
|
|
case PTHREAD_PRIO_PROTECT:
|
|
/* Check for a priority ceiling violation: */
|
|
if (_thread_run->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 = _thread_run;
|
|
|
|
/* Track number of priority mutexes owned: */
|
|
_thread_run->priority_mutex_count++;
|
|
|
|
/*
|
|
* The running thread inherits the ceiling
|
|
* priority of the mutex and executes at that
|
|
* priority.
|
|
*/
|
|
_thread_run->active_priority = (*mutex)->m_prio;
|
|
(*mutex)->m_saved_prio =
|
|
_thread_run->inherited_priority;
|
|
_thread_run->inherited_priority =
|
|
(*mutex)->m_prio;
|
|
|
|
/* Add to the list of owned mutexes: */
|
|
_MUTEX_ASSERT_NOT_OWNED(*mutex);
|
|
TAILQ_INSERT_TAIL(&_thread_run->mutexq,
|
|
(*mutex), m_qe);
|
|
} else if ((*mutex)->m_owner == _thread_run)
|
|
ret = mutex_self_trylock(*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: */
|
|
_SPINUNLOCK(&(*mutex)->lock);
|
|
|
|
/*
|
|
* Undefer and handle pending signals, yielding if
|
|
* necessary:
|
|
*/
|
|
_thread_kern_sig_undefer();
|
|
}
|
|
|
|
/* Return the completion status: */
|
|
return (ret);
|
|
}
|
|
|
|
int
|
|
pthread_mutex_lock(pthread_mutex_t * mutex)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (_thread_initial == NULL)
|
|
_thread_init();
|
|
|
|
if (mutex == NULL)
|
|
return (EINVAL);
|
|
|
|
/*
|
|
* If the mutex is statically initialized, perform the dynamic
|
|
* initialization:
|
|
*/
|
|
if ((*mutex == NULL) &&
|
|
((ret = init_static(mutex)) != 0))
|
|
return (ret);
|
|
|
|
/* Reset the interrupted flag: */
|
|
_thread_run->interrupted = 0;
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
while (((*mutex)->m_owner != _thread_run) && (ret == 0) &&
|
|
(_thread_run->interrupted == 0)) {
|
|
/*
|
|
* Defer signals to protect the scheduling queues from
|
|
* access by the signal handler:
|
|
*/
|
|
_thread_kern_sig_defer();
|
|
|
|
/* Lock the mutex structure: */
|
|
_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);
|
|
}
|
|
|
|
/* Process according to mutex type: */
|
|
switch ((*mutex)->m_protocol) {
|
|
/* Default POSIX mutex: */
|
|
case PTHREAD_PRIO_NONE:
|
|
if ((*mutex)->m_owner == NULL) {
|
|
/* Lock the mutex for this thread: */
|
|
(*mutex)->m_owner = _thread_run;
|
|
|
|
/* Add to the list of owned mutexes: */
|
|
_MUTEX_ASSERT_NOT_OWNED(*mutex);
|
|
TAILQ_INSERT_TAIL(&_thread_run->mutexq,
|
|
(*mutex), m_qe);
|
|
|
|
} else if ((*mutex)->m_owner == _thread_run)
|
|
ret = mutex_self_lock(*mutex);
|
|
else {
|
|
/*
|
|
* Join the queue of threads waiting to lock
|
|
* the mutex:
|
|
*/
|
|
mutex_queue_enq(*mutex, _thread_run);
|
|
|
|
/*
|
|
* Keep a pointer to the mutex this thread
|
|
* is waiting on:
|
|
*/
|
|
_thread_run->data.mutex = *mutex;
|
|
|
|
/*
|
|
* Unlock the mutex structure and schedule the
|
|
* next thread:
|
|
*/
|
|
_thread_kern_sched_state_unlock(PS_MUTEX_WAIT,
|
|
&(*mutex)->lock, __FILE__, __LINE__);
|
|
|
|
/* Lock the mutex structure again: */
|
|
_SPINLOCK(&(*mutex)->lock);
|
|
}
|
|
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 this thread: */
|
|
(*mutex)->m_owner = _thread_run;
|
|
|
|
/* Track number of priority mutexes owned: */
|
|
_thread_run->priority_mutex_count++;
|
|
|
|
/*
|
|
* The mutex takes on attributes of the
|
|
* running thread when there are no waiters.
|
|
*/
|
|
(*mutex)->m_prio = _thread_run->active_priority;
|
|
(*mutex)->m_saved_prio =
|
|
_thread_run->inherited_priority;
|
|
_thread_run->inherited_priority =
|
|
(*mutex)->m_prio;
|
|
|
|
/* Add to the list of owned mutexes: */
|
|
_MUTEX_ASSERT_NOT_OWNED(*mutex);
|
|
TAILQ_INSERT_TAIL(&_thread_run->mutexq,
|
|
(*mutex), m_qe);
|
|
|
|
} else if ((*mutex)->m_owner == _thread_run)
|
|
ret = mutex_self_lock(*mutex);
|
|
else {
|
|
/*
|
|
* Join the queue of threads waiting to lock
|
|
* the mutex:
|
|
*/
|
|
mutex_queue_enq(*mutex, _thread_run);
|
|
|
|
/*
|
|
* Keep a pointer to the mutex this thread
|
|
* is waiting on:
|
|
*/
|
|
_thread_run->data.mutex = *mutex;
|
|
|
|
if (_thread_run->active_priority >
|
|
(*mutex)->m_prio)
|
|
/* Adjust priorities: */
|
|
mutex_priority_adjust(*mutex);
|
|
|
|
/*
|
|
* Unlock the mutex structure and schedule the
|
|
* next thread:
|
|
*/
|
|
_thread_kern_sched_state_unlock(PS_MUTEX_WAIT,
|
|
&(*mutex)->lock, __FILE__, __LINE__);
|
|
|
|
/* Lock the mutex structure again: */
|
|
_SPINLOCK(&(*mutex)->lock);
|
|
}
|
|
break;
|
|
|
|
/* POSIX priority protection mutex: */
|
|
case PTHREAD_PRIO_PROTECT:
|
|
/* Check for a priority ceiling violation: */
|
|
if (_thread_run->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 = _thread_run;
|
|
|
|
/* Track number of priority mutexes owned: */
|
|
_thread_run->priority_mutex_count++;
|
|
|
|
/*
|
|
* The running thread inherits the ceiling
|
|
* priority of the mutex and executes at that
|
|
* priority:
|
|
*/
|
|
_thread_run->active_priority = (*mutex)->m_prio;
|
|
(*mutex)->m_saved_prio =
|
|
_thread_run->inherited_priority;
|
|
_thread_run->inherited_priority =
|
|
(*mutex)->m_prio;
|
|
|
|
/* Add to the list of owned mutexes: */
|
|
_MUTEX_ASSERT_NOT_OWNED(*mutex);
|
|
TAILQ_INSERT_TAIL(&_thread_run->mutexq,
|
|
(*mutex), m_qe);
|
|
} else if ((*mutex)->m_owner == _thread_run)
|
|
ret = mutex_self_lock(*mutex);
|
|
else {
|
|
/*
|
|
* Join the queue of threads waiting to lock
|
|
* the mutex:
|
|
*/
|
|
mutex_queue_enq(*mutex, _thread_run);
|
|
|
|
/*
|
|
* Keep a pointer to the mutex this thread
|
|
* is waiting on:
|
|
*/
|
|
_thread_run->data.mutex = *mutex;
|
|
|
|
/* Clear any previous error: */
|
|
_thread_run->error = 0;
|
|
|
|
/*
|
|
* Unlock the mutex structure and schedule the
|
|
* next thread:
|
|
*/
|
|
_thread_kern_sched_state_unlock(PS_MUTEX_WAIT,
|
|
&(*mutex)->lock, __FILE__, __LINE__);
|
|
|
|
/* Lock the mutex structure again: */
|
|
_SPINLOCK(&(*mutex)->lock);
|
|
|
|
/*
|
|
* The threads priority may have changed while
|
|
* waiting for the mutex causing a ceiling
|
|
* violation.
|
|
*/
|
|
ret = _thread_run->error;
|
|
_thread_run->error = 0;
|
|
}
|
|
break;
|
|
|
|
/* Trap invalid mutex types: */
|
|
default:
|
|
/* Return an invalid argument error: */
|
|
ret = EINVAL;
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Check to see if this thread was interrupted and
|
|
* is still in the mutex queue of waiting threads:
|
|
*/
|
|
if (_thread_run->interrupted != 0)
|
|
mutex_queue_remove(*mutex, _thread_run);
|
|
|
|
/* Unlock the mutex structure: */
|
|
_SPINUNLOCK(&(*mutex)->lock);
|
|
|
|
/*
|
|
* Undefer and handle pending signals, yielding if
|
|
* necessary:
|
|
*/
|
|
_thread_kern_sig_undefer();
|
|
}
|
|
|
|
if (_thread_run->interrupted != 0 &&
|
|
_thread_run->continuation != NULL)
|
|
_thread_run->continuation((void *) _thread_run);
|
|
|
|
/* Return the completion status: */
|
|
return (ret);
|
|
}
|
|
|
|
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);
|
|
}
|
|
|
|
static inline int
|
|
mutex_self_trylock(pthread_mutex_t mutex)
|
|
{
|
|
int ret = 0;
|
|
|
|
switch (mutex->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.
|
|
*/
|
|
ret = EBUSY;
|
|
break;
|
|
|
|
case PTHREAD_MUTEX_RECURSIVE:
|
|
/* Increment the lock count: */
|
|
mutex->m_data.m_count++;
|
|
break;
|
|
|
|
default:
|
|
/* Trap invalid mutex types; */
|
|
ret = EINVAL;
|
|
}
|
|
|
|
return(ret);
|
|
}
|
|
|
|
static inline int
|
|
mutex_self_lock(pthread_mutex_t mutex)
|
|
{
|
|
int ret = 0;
|
|
|
|
switch (mutex->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.
|
|
*/
|
|
_thread_kern_sched_state_unlock(PS_DEADLOCK,
|
|
&mutex->lock, __FILE__, __LINE__);
|
|
break;
|
|
|
|
case PTHREAD_MUTEX_RECURSIVE:
|
|
/* Increment the lock count: */
|
|
mutex->m_data.m_count++;
|
|
break;
|
|
|
|
default:
|
|
/* Trap invalid mutex types; */
|
|
ret = EINVAL;
|
|
}
|
|
|
|
return(ret);
|
|
}
|
|
|
|
static inline int
|
|
mutex_unlock_common(pthread_mutex_t * mutex, int add_reference)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (mutex == NULL || *mutex == NULL) {
|
|
ret = EINVAL;
|
|
} else {
|
|
/*
|
|
* Defer signals to protect the scheduling queues from
|
|
* access by the signal handler:
|
|
*/
|
|
_thread_kern_sig_defer();
|
|
|
|
/* Lock the mutex structure: */
|
|
_SPINLOCK(&(*mutex)->lock);
|
|
|
|
/* Process according to mutex type: */
|
|
switch ((*mutex)->m_protocol) {
|
|
/* Default POSIX mutex: */
|
|
case PTHREAD_PRIO_NONE:
|
|
/*
|
|
* Check if the running thread is not the owner of the
|
|
* mutex:
|
|
*/
|
|
if ((*mutex)->m_owner != _thread_run) {
|
|
/*
|
|
* Return an invalid argument error for no
|
|
* owner and a permission error otherwise:
|
|
*/
|
|
ret = (*mutex)->m_owner == NULL ? EINVAL : EPERM;
|
|
}
|
|
else if (((*mutex)->m_type == PTHREAD_MUTEX_RECURSIVE) &&
|
|
((*mutex)->m_data.m_count > 0)) {
|
|
/* Decrement the count: */
|
|
(*mutex)->m_data.m_count--;
|
|
} else {
|
|
/*
|
|
* Clear the count in case this is recursive
|
|
* mutex.
|
|
*/
|
|
(*mutex)->m_data.m_count = 0;
|
|
|
|
/* Remove the mutex from the threads queue. */
|
|
_MUTEX_ASSERT_IS_OWNED(*mutex);
|
|
TAILQ_REMOVE(&(*mutex)->m_owner->mutexq,
|
|
(*mutex), m_qe);
|
|
_MUTEX_INIT_LINK(*mutex);
|
|
|
|
/*
|
|
* Get the next thread from the queue of
|
|
* threads waiting on the mutex:
|
|
*/
|
|
if (((*mutex)->m_owner =
|
|
mutex_queue_deq(*mutex)) != NULL) {
|
|
/*
|
|
* Unless the new owner of the mutex is
|
|
* currently suspended, allow the owner
|
|
* to run. If the thread is suspended,
|
|
* make a note that the thread isn't in
|
|
* a wait queue any more.
|
|
*/
|
|
if (((*mutex)->m_owner->state !=
|
|
PS_SUSPENDED)) {
|
|
PTHREAD_NEW_STATE((*mutex)->m_owner,
|
|
PS_RUNNING);
|
|
} else {
|
|
(*mutex)->m_owner->suspended =
|
|
SUSP_NOWAIT;
|
|
}
|
|
|
|
/*
|
|
* Add the mutex to the threads list of
|
|
* owned mutexes:
|
|
*/
|
|
TAILQ_INSERT_TAIL(&(*mutex)->m_owner->mutexq,
|
|
(*mutex), m_qe);
|
|
|
|
/*
|
|
* The owner is no longer waiting for
|
|
* this mutex:
|
|
*/
|
|
(*mutex)->m_owner->data.mutex = NULL;
|
|
}
|
|
}
|
|
break;
|
|
|
|
/* POSIX priority inheritence mutex: */
|
|
case PTHREAD_PRIO_INHERIT:
|
|
/*
|
|
* Check if the running thread is not the owner of the
|
|
* mutex:
|
|
*/
|
|
if ((*mutex)->m_owner != _thread_run) {
|
|
/*
|
|
* Return an invalid argument error for no
|
|
* owner and a permission error otherwise:
|
|
*/
|
|
ret = (*mutex)->m_owner == NULL ? EINVAL : EPERM;
|
|
}
|
|
else if (((*mutex)->m_type == PTHREAD_MUTEX_RECURSIVE) &&
|
|
((*mutex)->m_data.m_count > 0)) {
|
|
/* Decrement the count: */
|
|
(*mutex)->m_data.m_count--;
|
|
} else {
|
|
/*
|
|
* Clear the count in case this is recursive
|
|
* mutex.
|
|
*/
|
|
(*mutex)->m_data.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).
|
|
*/
|
|
_thread_run->inherited_priority =
|
|
(*mutex)->m_saved_prio;
|
|
_thread_run->active_priority =
|
|
MAX(_thread_run->inherited_priority,
|
|
_thread_run->base_priority);
|
|
|
|
/*
|
|
* This thread now owns one less priority mutex.
|
|
*/
|
|
_thread_run->priority_mutex_count--;
|
|
|
|
/* Remove the mutex from the threads queue. */
|
|
_MUTEX_ASSERT_IS_OWNED(*mutex);
|
|
TAILQ_REMOVE(&(*mutex)->m_owner->mutexq,
|
|
(*mutex), m_qe);
|
|
_MUTEX_INIT_LINK(*mutex);
|
|
|
|
/*
|
|
* Get the next thread from the queue of threads
|
|
* waiting on the mutex:
|
|
*/
|
|
if (((*mutex)->m_owner =
|
|
mutex_queue_deq(*mutex)) == NULL)
|
|
/* This mutex has no priority. */
|
|
(*mutex)->m_prio = 0;
|
|
else {
|
|
/*
|
|
* Track number of priority mutexes owned:
|
|
*/
|
|
(*mutex)->m_owner->priority_mutex_count++;
|
|
|
|
/*
|
|
* Add the mutex to the threads list
|
|
* of owned mutexes:
|
|
*/
|
|
TAILQ_INSERT_TAIL(&(*mutex)->m_owner->mutexq,
|
|
(*mutex), m_qe);
|
|
|
|
/*
|
|
* The owner is no longer waiting for
|
|
* this mutex:
|
|
*/
|
|
(*mutex)->m_owner->data.mutex = NULL;
|
|
|
|
/*
|
|
* 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 =
|
|
(*mutex)->m_owner->active_priority;
|
|
|
|
/*
|
|
* Save the owning threads inherited
|
|
* priority:
|
|
*/
|
|
(*mutex)->m_saved_prio =
|
|
(*mutex)->m_owner->inherited_priority;
|
|
|
|
/*
|
|
* The owning threads inherited priority
|
|
* now becomes his active priority (the
|
|
* priority of the mutex).
|
|
*/
|
|
(*mutex)->m_owner->inherited_priority =
|
|
(*mutex)->m_prio;
|
|
|
|
/*
|
|
* Unless the new owner of the mutex is
|
|
* currently suspended, allow the owner
|
|
* to run. If the thread is suspended,
|
|
* make a note that the thread isn't in
|
|
* a wait queue any more.
|
|
*/
|
|
if (((*mutex)->m_owner->state !=
|
|
PS_SUSPENDED)) {
|
|
PTHREAD_NEW_STATE((*mutex)->m_owner,
|
|
PS_RUNNING);
|
|
} else {
|
|
(*mutex)->m_owner->suspended =
|
|
SUSP_NOWAIT;
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
|
|
/* POSIX priority ceiling mutex: */
|
|
case PTHREAD_PRIO_PROTECT:
|
|
/*
|
|
* Check if the running thread is not the owner of the
|
|
* mutex:
|
|
*/
|
|
if ((*mutex)->m_owner != _thread_run) {
|
|
/*
|
|
* Return an invalid argument error for no
|
|
* owner and a permission error otherwise:
|
|
*/
|
|
ret = (*mutex)->m_owner == NULL ? EINVAL : EPERM;
|
|
}
|
|
else if (((*mutex)->m_type == PTHREAD_MUTEX_RECURSIVE) &&
|
|
((*mutex)->m_data.m_count > 0)) {
|
|
/* Decrement the count: */
|
|
(*mutex)->m_data.m_count--;
|
|
} else {
|
|
/*
|
|
* Clear the count in case this is recursive
|
|
* mutex.
|
|
*/
|
|
(*mutex)->m_data.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).
|
|
*/
|
|
_thread_run->inherited_priority =
|
|
(*mutex)->m_saved_prio;
|
|
_thread_run->active_priority =
|
|
MAX(_thread_run->inherited_priority,
|
|
_thread_run->base_priority);
|
|
|
|
/*
|
|
* This thread now owns one less priority mutex.
|
|
*/
|
|
_thread_run->priority_mutex_count--;
|
|
|
|
/* Remove the mutex from the threads queue. */
|
|
_MUTEX_ASSERT_IS_OWNED(*mutex);
|
|
TAILQ_REMOVE(&(*mutex)->m_owner->mutexq,
|
|
(*mutex), m_qe);
|
|
_MUTEX_INIT_LINK(*mutex);
|
|
|
|
/*
|
|
* Enter a loop to find a waiting thread whose
|
|
* active priority will not cause a ceiling
|
|
* violation:
|
|
*/
|
|
while ((((*mutex)->m_owner =
|
|
mutex_queue_deq(*mutex)) != NULL) &&
|
|
((*mutex)->m_owner->active_priority >
|
|
(*mutex)->m_prio)) {
|
|
/*
|
|
* Either the mutex ceiling priority
|
|
* been lowered and/or this threads
|
|
* priority has been raised subsequent
|
|
* to this thread being queued on the
|
|
* waiting list.
|
|
*/
|
|
(*mutex)->m_owner->error = EINVAL;
|
|
PTHREAD_NEW_STATE((*mutex)->m_owner,
|
|
PS_RUNNING);
|
|
/*
|
|
* The thread is no longer waiting for
|
|
* this mutex:
|
|
*/
|
|
(*mutex)->m_owner->data.mutex = NULL;
|
|
}
|
|
|
|
/* Check for a new owner: */
|
|
if ((*mutex)->m_owner != NULL) {
|
|
/*
|
|
* Track number of priority mutexes owned:
|
|
*/
|
|
(*mutex)->m_owner->priority_mutex_count++;
|
|
|
|
/*
|
|
* Add the mutex to the threads list
|
|
* of owned mutexes:
|
|
*/
|
|
TAILQ_INSERT_TAIL(&(*mutex)->m_owner->mutexq,
|
|
(*mutex), m_qe);
|
|
|
|
/*
|
|
* The owner is no longer waiting for
|
|
* this mutex:
|
|
*/
|
|
(*mutex)->m_owner->data.mutex = NULL;
|
|
|
|
/*
|
|
* Save the owning threads inherited
|
|
* priority:
|
|
*/
|
|
(*mutex)->m_saved_prio =
|
|
(*mutex)->m_owner->inherited_priority;
|
|
|
|
/*
|
|
* The owning thread inherits the
|
|
* ceiling priority of the mutex and
|
|
* executes at that priority:
|
|
*/
|
|
(*mutex)->m_owner->inherited_priority =
|
|
(*mutex)->m_prio;
|
|
(*mutex)->m_owner->active_priority =
|
|
(*mutex)->m_prio;
|
|
|
|
/*
|
|
* Unless the new owner of the mutex is
|
|
* currently suspended, allow the owner
|
|
* to run. If the thread is suspended,
|
|
* make a note that the thread isn't in
|
|
* a wait queue any more.
|
|
*/
|
|
if (((*mutex)->m_owner->state !=
|
|
PS_SUSPENDED)) {
|
|
PTHREAD_NEW_STATE((*mutex)->m_owner,
|
|
PS_RUNNING);
|
|
} else {
|
|
(*mutex)->m_owner->suspended =
|
|
SUSP_NOWAIT;
|
|
}
|
|
}
|
|
}
|
|
break;
|
|
|
|
/* Trap invalid mutex types: */
|
|
default:
|
|
/* Return an invalid argument error: */
|
|
ret = EINVAL;
|
|
break;
|
|
}
|
|
|
|
if ((ret == 0) && (add_reference != 0)) {
|
|
/* Increment the reference count: */
|
|
(*mutex)->m_refcount++;
|
|
}
|
|
|
|
/* Unlock the mutex structure: */
|
|
_SPINUNLOCK(&(*mutex)->lock);
|
|
|
|
/*
|
|
* Undefer and handle pending signals, yielding if
|
|
* necessary:
|
|
*/
|
|
_thread_kern_sig_undefer();
|
|
}
|
|
|
|
/* 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 while thread scheduling is deferred.
|
|
*/
|
|
void
|
|
_mutex_notify_priochange(pthread_t pthread)
|
|
{
|
|
/* 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.
|
|
*/
|
|
mutex_rescan_owned(pthread, /* rescan all owned */ NULL);
|
|
}
|
|
|
|
/*
|
|
* If this thread is waiting on a priority inheritence mutex,
|
|
* check for priority adjustments. A change in priority can
|
|
* also effect 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 (pthread->state == PS_MUTEX_WAIT) {
|
|
/* Lock the mutex structure: */
|
|
_SPINLOCK(&pthread->data.mutex->lock);
|
|
|
|
/*
|
|
* Check to make sure this thread is still in the same state
|
|
* (the spinlock above can yield the CPU to another thread):
|
|
*/
|
|
if (pthread->state == PS_MUTEX_WAIT) {
|
|
/*
|
|
* Remove and reinsert this thread into the list of
|
|
* waiting threads to preserve decreasing priority
|
|
* order.
|
|
*/
|
|
mutex_queue_remove(pthread->data.mutex, pthread);
|
|
mutex_queue_enq(pthread->data.mutex, pthread);
|
|
|
|
if (pthread->data.mutex->m_protocol ==
|
|
PTHREAD_PRIO_INHERIT) {
|
|
/* Adjust priorities: */
|
|
mutex_priority_adjust(pthread->data.mutex);
|
|
}
|
|
}
|
|
|
|
/* Unlock the mutex structure: */
|
|
_SPINUNLOCK(&pthread->data.mutex->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.
|
|
*/
|
|
static void
|
|
mutex_priority_adjust(pthread_mutex_t mutex)
|
|
{
|
|
pthread_t pthread_next, pthread = mutex->m_owner;
|
|
int temp_prio;
|
|
pthread_mutex_t m = mutex;
|
|
|
|
/*
|
|
* 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;
|
|
|
|
while (m != NULL) {
|
|
/*
|
|
* Save the threads priority before rescanning the
|
|
* owned mutexes:
|
|
*/
|
|
temp_prio = pthread->active_priority;
|
|
|
|
/*
|
|
* Fix the priorities for all the mutexes this thread has
|
|
* locked since taking this mutex. This also has a
|
|
* potential side-effect of changing the threads priority.
|
|
*/
|
|
mutex_rescan_owned(pthread, m);
|
|
|
|
/*
|
|
* 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->state == PS_MUTEX_WAIT) &&
|
|
(pthread->data.mutex->m_protocol == PTHREAD_PRIO_INHERIT)) {
|
|
/* Grab the mutex this thread is waiting on: */
|
|
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;
|
|
}
|
|
else
|
|
/* We're done: */
|
|
m = NULL;
|
|
|
|
}
|
|
else
|
|
/* We're done: */
|
|
m = NULL;
|
|
}
|
|
}
|
|
|
|
static void
|
|
mutex_rescan_owned(pthread_t pthread, pthread_mutex_t mutex)
|
|
{
|
|
int active_prio, inherited_prio;
|
|
pthread_mutex_t m;
|
|
pthread_t pthread_next;
|
|
|
|
/*
|
|
* 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);
|
|
|
|
while (m != NULL) {
|
|
/*
|
|
* 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);
|
|
}
|
|
|
|
/* Advance to the next mutex owned by this thread: */
|
|
m = TAILQ_NEXT(m, m_qe);
|
|
}
|
|
|
|
/*
|
|
* 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) {
|
|
/*
|
|
* If this thread is in the priority queue, it must be
|
|
* removed and reinserted for its new priority.
|
|
*/
|
|
if (pthread->flags & PTHREAD_FLAGS_IN_PRIOQ) {
|
|
/*
|
|
* Remove the thread from the priority queue
|
|
* before changing its priority:
|
|
*/
|
|
PTHREAD_PRIOQ_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;
|
|
|
|
PTHREAD_PRIOQ_INSERT_HEAD(pthread);
|
|
}
|
|
else {
|
|
/* Set the new active priority. */
|
|
pthread->active_priority = active_prio;
|
|
|
|
PTHREAD_PRIOQ_INSERT_TAIL(pthread);
|
|
}
|
|
}
|
|
else {
|
|
/* Set the new active priority. */
|
|
pthread->active_priority = active_prio;
|
|
}
|
|
}
|
|
}
|
|
|
|
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;
|
|
|
|
/*
|
|
* Defer signals to protect the scheduling queues from
|
|
* access by the signal handler:
|
|
*/
|
|
_thread_kern_sig_defer();
|
|
if ((pthread->flags & PTHREAD_FLAGS_IN_MUTEXQ) != 0) {
|
|
mutex = pthread->data.mutex;
|
|
|
|
/* Lock the mutex structure: */
|
|
_SPINLOCK(&mutex->lock);
|
|
|
|
mutex_queue_remove(mutex, pthread);
|
|
|
|
/* This thread is no longer waiting for the mutex: */
|
|
pthread->data.mutex = NULL;
|
|
|
|
/* Unlock the mutex structure: */
|
|
_SPINUNLOCK(&mutex->lock);
|
|
|
|
}
|
|
/*
|
|
* Undefer and handle pending signals, yielding if
|
|
* necessary:
|
|
*/
|
|
_thread_kern_sig_undefer();
|
|
}
|
|
|
|
/*
|
|
* Dequeue a waiting thread from the head of a mutex queue in descending
|
|
* priority order.
|
|
*/
|
|
static inline pthread_t
|
|
mutex_queue_deq(pthread_mutex_t mutex)
|
|
{
|
|
pthread_t pthread;
|
|
|
|
while ((pthread = TAILQ_FIRST(&mutex->m_queue)) != NULL) {
|
|
TAILQ_REMOVE(&mutex->m_queue, pthread, sqe);
|
|
pthread->flags &= ~PTHREAD_FLAGS_IN_MUTEXQ;
|
|
|
|
/*
|
|
* 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->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);
|
|
|
|
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);
|
|
}
|
|
pthread->flags |= PTHREAD_FLAGS_IN_MUTEXQ;
|
|
}
|
|
|
|
#endif
|