rjw | 1f88458 | 2022-01-06 17:20:42 +0800 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (c) 2008-2014 Travis Geiselbrecht |
| 3 | * Copyright (c) 2012-2012 Shantanu Gupta |
| 4 | * |
| 5 | * Permission is hereby granted, free of charge, to any person obtaining |
| 6 | * a copy of this software and associated documentation files |
| 7 | * (the "Software"), to deal in the Software without restriction, |
| 8 | * including without limitation the rights to use, copy, modify, merge, |
| 9 | * publish, distribute, sublicense, and/or sell copies of the Software, |
| 10 | * and to permit persons to whom the Software is furnished to do so, |
| 11 | * subject to the following conditions: |
| 12 | * |
| 13 | * The above copyright notice and this permission notice shall be |
| 14 | * included in all copies or substantial portions of the Software. |
| 15 | * |
| 16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| 17 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| 18 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
| 19 | * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
| 20 | * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
| 21 | * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
| 22 | * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
| 23 | */ |
| 24 | |
| 25 | /** |
| 26 | * @file |
| 27 | * @brief Mutex functions |
| 28 | * |
| 29 | * @defgroup mutex Mutex |
| 30 | * @{ |
| 31 | */ |
| 32 | |
| 33 | #include <kernel/mutex.h> |
| 34 | #include <debug.h> |
| 35 | #include <assert.h> |
| 36 | #include <err.h> |
| 37 | #include <kernel/thread.h> |
| 38 | |
| 39 | /** |
| 40 | * @brief Initialize a mutex_t |
| 41 | */ |
| 42 | void mutex_init(mutex_t *m) |
| 43 | { |
| 44 | *m = (mutex_t)MUTEX_INITIAL_VALUE(*m); |
| 45 | } |
| 46 | |
| 47 | /** |
| 48 | * @brief Destroy a mutex_t |
| 49 | * |
| 50 | * This function frees any resources that were allocated |
| 51 | * in mutex_init(). The mutex_t object itself is not freed. |
| 52 | */ |
| 53 | void mutex_destroy(mutex_t *m) |
| 54 | { |
| 55 | DEBUG_ASSERT(m->magic == MUTEX_MAGIC); |
| 56 | |
| 57 | #if LK_DEBUGLEVEL > 0 |
| 58 | if (unlikely(m->holder != 0 && get_current_thread() != m->holder)) |
| 59 | panic("mutex_destroy: thread %p (%s) tried to release mutex %p it doesn't own. owned by %p (%s)\n", |
| 60 | get_current_thread(), get_current_thread()->name, m, m->holder, m->holder->name); |
| 61 | #endif |
| 62 | |
| 63 | THREAD_LOCK(state); |
| 64 | m->magic = 0; |
| 65 | m->count = 0; |
| 66 | wait_queue_destroy(&m->wait, true); |
| 67 | THREAD_UNLOCK(state); |
| 68 | } |
| 69 | |
| 70 | /** |
| 71 | * @brief Mutex wait with timeout |
| 72 | * |
| 73 | * This function waits up to \a timeout ms for the mutex to become available. |
| 74 | * Timeout may be zero, in which case this function returns immediately if |
| 75 | * the mutex is not free. |
| 76 | * |
| 77 | * @return NO_ERROR on success, ERR_TIMED_OUT on timeout, |
| 78 | * other values on error |
| 79 | */ |
| 80 | status_t mutex_acquire_timeout(mutex_t *m, lk_time_t timeout) |
| 81 | { |
| 82 | DEBUG_ASSERT(m->magic == MUTEX_MAGIC); |
| 83 | |
| 84 | #if LK_DEBUGLEVEL > 0 |
| 85 | if (unlikely(get_current_thread() == m->holder)) |
| 86 | panic("mutex_acquire_timeout: thread %p (%s) tried to acquire mutex %p it already owns.\n", |
| 87 | get_current_thread(), get_current_thread()->name, m); |
| 88 | #endif |
| 89 | |
| 90 | THREAD_LOCK(state); |
| 91 | |
| 92 | status_t ret = NO_ERROR; |
| 93 | if (unlikely(++m->count > 1)) { |
| 94 | ret = wait_queue_block(&m->wait, timeout); |
| 95 | if (unlikely(ret < NO_ERROR)) { |
| 96 | /* if the acquisition timed out, back out the acquire and exit */ |
| 97 | if (likely(ret == ERR_TIMED_OUT)) { |
| 98 | /* |
| 99 | * race: the mutex may have been destroyed after the timeout, |
| 100 | * but before we got scheduled again which makes messing with the |
| 101 | * count variable dangerous. |
| 102 | */ |
| 103 | m->count--; |
| 104 | } |
| 105 | /* if there was a general error, it may have been destroyed out from |
| 106 | * underneath us, so just exit (which is really an invalid state anyway) |
| 107 | */ |
| 108 | goto err; |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | m->holder = get_current_thread(); |
| 113 | |
| 114 | err: |
| 115 | THREAD_UNLOCK(state); |
| 116 | return ret; |
| 117 | } |
| 118 | |
| 119 | /** |
| 120 | * @brief Release mutex |
| 121 | */ |
| 122 | status_t mutex_release(mutex_t *m) |
| 123 | { |
| 124 | DEBUG_ASSERT(m->magic == MUTEX_MAGIC); |
| 125 | |
| 126 | #if LK_DEBUGLEVEL > 0 |
| 127 | if (unlikely(get_current_thread() != m->holder)) { |
| 128 | panic("mutex_release: thread %p (%s) tried to release mutex %p it doesn't own. owned by %p (%s)\n", |
| 129 | get_current_thread(), get_current_thread()->name, m, m->holder, m->holder ? m->holder->name : "none"); |
| 130 | } |
| 131 | #endif |
| 132 | |
| 133 | THREAD_LOCK(state); |
| 134 | |
| 135 | m->holder = 0; |
| 136 | |
| 137 | if (unlikely(--m->count >= 1)) { |
| 138 | /* release a thread */ |
| 139 | wait_queue_wake_one(&m->wait, true, NO_ERROR); |
| 140 | } |
| 141 | |
| 142 | THREAD_UNLOCK(state); |
| 143 | return NO_ERROR; |
| 144 | } |
| 145 | |