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