209 lines
5.3 KiB
C
209 lines
5.3 KiB
C
/*
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* Copyright (c) 2008-2009 Travis Geiselbrecht
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files
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* (the "Software"), to deal in the Software without restriction,
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* including without limitation the rights to use, copy, modify, merge,
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* publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so,
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* subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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/**
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* @file
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* @brief Mutex functions
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*
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* @defgroup mutex Mutex
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* @{
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*/
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#include <debug.h>
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#include <err.h>
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#include <kernel/mutex.h>
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#include <kernel/thread.h>
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#if DEBUGLEVEL > 1
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#define MUTEX_CHECK 1
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#endif
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/**
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* @brief Initialize a mutex_t
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*/
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void mutex_init(mutex_t *m)
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{
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#if MUTEX_CHECK
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// ASSERT(m->magic != MUTEX_MAGIC);
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#endif
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m->magic = MUTEX_MAGIC;
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m->count = 0;
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m->holder = 0;
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wait_queue_init(&m->wait);
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}
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/**
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* @brief Destroy a mutex_t
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*
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* This function frees any resources that were allocated
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* in mutex_init(). The mutex_t object itself is not freed.
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*/
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void mutex_destroy(mutex_t *m)
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{
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enter_critical_section();
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#if MUTEX_CHECK
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ASSERT(m->magic == MUTEX_MAGIC);
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#endif
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// if (m->holder != 0 && current_thread != m->holder)
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// panic("mutex_destroy: thread %p (%s) tried to release mutex %p it doesn't own. owned by %p (%s)\n",
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// current_thread, current_thread->name, m, m->holder, m->holder ? m->holder->name : "none");
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m->magic = 0;
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m->count = 0;
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wait_queue_destroy(&m->wait, true);
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exit_critical_section();
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}
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/**
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* @brief Acquire a mutex; wait if needed.
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*
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* This function waits for a mutex to become available. It
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* may wait forever if the mutex never becomes free.
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*
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* @return NO_ERROR on success, other values on error
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*/
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status_t mutex_acquire(mutex_t *m)
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{
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status_t ret = NO_ERROR;
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if (current_thread == m->holder)
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panic("mutex_acquire: thread %p (%s) tried to acquire mutex %p it already owns.\n",
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current_thread, current_thread->name, m);
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enter_critical_section();
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#if MUTEX_CHECK
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ASSERT(m->magic == MUTEX_MAGIC);
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#endif
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// dprintf("mutex_acquire: m %p, count %d, curr %p\n", m, m->count, current_thread);
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m->count++;
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if (unlikely(m->count > 1)) {
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/*
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* block on the wait queue. If it returns an error, it was likely destroyed
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* out from underneath us, so make sure we dont scribble thread ownership
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* on the mutex.
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*/
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ret = wait_queue_block(&m->wait, INFINITE_TIME);
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if (ret < 0)
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goto err;
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}
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m->holder = current_thread;
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err:
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exit_critical_section();
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return ret;
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}
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/**
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* @brief Mutex wait with timeout
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*
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* This function waits up to \a timeout ms for the mutex to become available.
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* Timeout may be zero, in which case this function returns immediately if
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* the mutex is not free.
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*
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* @return NO_ERROR on success, ERR_TIMED_OUT on timeout,
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* other values on error
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*/
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status_t mutex_acquire_timeout(mutex_t *m, time_t timeout)
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{
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status_t ret = NO_ERROR;
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if (current_thread == m->holder)
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panic("mutex_acquire_timeout: thread %p (%s) tried to acquire mutex %p it already owns.\n",
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current_thread, current_thread->name, m);
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if (timeout == INFINITE_TIME)
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return mutex_acquire(m);
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enter_critical_section();
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#if MUTEX_CHECK
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ASSERT(m->magic == MUTEX_MAGIC);
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#endif
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// dprintf("mutex_acquire_timeout: m %p, count %d, curr %p, timeout %d\n", m, m->count, current_thread, timeout);
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m->count++;
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if (unlikely(m->count > 1)) {
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ret = wait_queue_block(&m->wait, timeout);
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if (ret < NO_ERROR) {
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/* if the acquisition timed out, back out the acquire and exit */
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if (ret == ERR_TIMED_OUT) {
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/*
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* XXX race: the mutex may have been destroyed after the timeout,
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* but before we got scheduled again which makes messing with the
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* count variable dangerous.
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*/
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m->count--;
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goto err;
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}
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/* if there was a general error, it may have been destroyed out from
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* underneath us, so just exit (which is really an invalid state anyway)
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*/
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}
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}
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m->holder = current_thread;
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err:
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exit_critical_section();
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return ret;
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}
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/**
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* @brief Release mutex
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*/
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status_t mutex_release(mutex_t *m)
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{
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if (current_thread != m->holder)
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panic("mutex_release: thread %p (%s) tried to release mutex %p it doesn't own. owned by %p (%s)\n",
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current_thread, current_thread->name, m, m->holder, m->holder ? m->holder->name : "none");
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enter_critical_section();
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#if MUTEX_CHECK
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ASSERT(m->magic == MUTEX_MAGIC);
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#endif
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// dprintf("mutex_release: m %p, count %d, holder %p, curr %p\n", m, m->count, m->holder, current_thread);
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m->holder = 0;
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m->count--;
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if (unlikely(m->count >= 1)) {
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/* release a thread */
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// dprintf("releasing thread\n");
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wait_queue_wake_one(&m->wait, true, NO_ERROR);
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}
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exit_critical_section();
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return NO_ERROR;
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}
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