| /* |
| * Copyright (c) 2008-2014 Travis Geiselbrecht |
| * Copyright (c) 2012-2012 Shantanu Gupta |
| * |
| * 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 <kernel/mutex.h> |
| #include <debug.h> |
| #include <assert.h> |
| #include <err.h> |
| #include <kernel/thread.h> |
| |
| /** |
| * @brief Initialize a mutex_t |
| */ |
| void mutex_init(mutex_t *m) |
| { |
| *m = (mutex_t)MUTEX_INITIAL_VALUE(*m); |
| } |
| |
| /** |
| * @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) |
| { |
| DEBUG_ASSERT(m->magic == MUTEX_MAGIC); |
| |
| #if LK_DEBUGLEVEL > 0 |
| if (unlikely(m->holder != 0 && get_current_thread() != m->holder)) |
| panic("mutex_destroy: thread %p (%s) tried to release mutex %p it doesn't own. owned by %p (%s)\n", |
| get_current_thread(), get_current_thread()->name, m, m->holder, m->holder->name); |
| #endif |
| |
| THREAD_LOCK(state); |
| m->magic = 0; |
| m->count = 0; |
| wait_queue_destroy(&m->wait, true); |
| THREAD_UNLOCK(state); |
| } |
| |
| /** |
| * @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, lk_time_t timeout) |
| { |
| DEBUG_ASSERT(m->magic == MUTEX_MAGIC); |
| |
| #if LK_DEBUGLEVEL > 0 |
| if (unlikely(get_current_thread() == m->holder)) |
| panic("mutex_acquire_timeout: thread %p (%s) tried to acquire mutex %p it already owns.\n", |
| get_current_thread(), get_current_thread()->name, m); |
| #endif |
| |
| THREAD_LOCK(state); |
| |
| status_t ret = NO_ERROR; |
| if (unlikely(++m->count > 1)) { |
| ret = wait_queue_block(&m->wait, timeout); |
| if (unlikely(ret < NO_ERROR)) { |
| /* if the acquisition timed out, back out the acquire and exit */ |
| if (likely(ret == ERR_TIMED_OUT)) { |
| /* |
| * 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--; |
| } |
| /* 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) |
| */ |
| goto err; |
| } |
| } |
| |
| m->holder = get_current_thread(); |
| |
| err: |
| THREAD_UNLOCK(state); |
| return ret; |
| } |
| |
| /** |
| * @brief Release mutex |
| */ |
| status_t mutex_release(mutex_t *m) |
| { |
| DEBUG_ASSERT(m->magic == MUTEX_MAGIC); |
| |
| #if LK_DEBUGLEVEL > 0 |
| if (unlikely(get_current_thread() != m->holder)) { |
| panic("mutex_release: thread %p (%s) tried to release mutex %p it doesn't own. owned by %p (%s)\n", |
| get_current_thread(), get_current_thread()->name, m, m->holder, m->holder ? m->holder->name : "none"); |
| } |
| #endif |
| |
| THREAD_LOCK(state); |
| |
| m->holder = 0; |
| |
| if (unlikely(--m->count >= 1)) { |
| /* release a thread */ |
| wait_queue_wake_one(&m->wait, true, NO_ERROR); |
| } |
| |
| THREAD_UNLOCK(state); |
| return NO_ERROR; |
| } |
| |