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Diffstat (limited to 'os/kernel/src/chmtx.c')
| -rw-r--r-- | os/kernel/src/chmtx.c | 393 |
1 files changed, 0 insertions, 393 deletions
diff --git a/os/kernel/src/chmtx.c b/os/kernel/src/chmtx.c deleted file mode 100644 index 84d7e53a6..000000000 --- a/os/kernel/src/chmtx.c +++ /dev/null @@ -1,393 +0,0 @@ -/*
- ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
- 2011,2012,2013 Giovanni Di Sirio.
-
- This file is part of ChibiOS/RT.
-
- ChibiOS/RT is free software; you can redistribute it and/or modify
- it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 3 of the License, or
- (at your option) any later version.
-
- ChibiOS/RT is distributed in the hope that it will be useful,
- but WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- GNU General Public License for more details.
-
- You should have received a copy of the GNU General Public License
- along with this program. If not, see <http://www.gnu.org/licenses/>.
-*/
-
-/**
- * @file chmtx.c
- * @brief Mutexes code.
- *
- * @addtogroup mutexes
- * @details Mutexes related APIs and services.
- *
- * <h2>Operation mode</h2>
- * A mutex is a threads synchronization object that can be in two
- * distinct states:
- * - Not owned (unlocked).
- * - Owned by a thread (locked).
- * .
- * Operations defined for mutexes:
- * - <b>Lock</b>: The mutex is checked, if the mutex is not owned by
- * some other thread then it is associated to the locking thread
- * else the thread is queued on the mutex in a list ordered by
- * priority.
- * - <b>Unlock</b>: The mutex is released by the owner and the highest
- * priority thread waiting in the queue, if any, is resumed and made
- * owner of the mutex.
- * .
- * <h2>Constraints</h2>
- * In ChibiOS/RT the Unlock operations are always performed in
- * lock-reverse order. The unlock API does not even have a parameter,
- * the mutex to unlock is selected from an internal, per-thread, stack
- * of owned mutexes. This both improves the performance and is
- * required for an efficient implementation of the priority
- * inheritance mechanism.
- *
- * <h2>The priority inversion problem</h2>
- * The mutexes in ChibiOS/RT implements the <b>full</b> priority
- * inheritance mechanism in order handle the priority inversion
- * problem.<br>
- * When a thread is queued on a mutex, any thread, directly or
- * indirectly, holding the mutex gains the same priority of the
- * waiting thread (if their priority was not already equal or higher).
- * The mechanism works with any number of nested mutexes and any
- * number of involved threads. The algorithm complexity (worst case)
- * is N with N equal to the number of nested mutexes.
- * @pre In order to use the mutex APIs the @p CH_USE_MUTEXES option
- * must be enabled in @p chconf.h.
- * @post Enabling mutexes requires 5-12 (depending on the architecture)
- * extra bytes in the @p Thread structure.
- * @{
- */
-
-#include "ch.h"
-
-#if CH_USE_MUTEXES || defined(__DOXYGEN__)
-
-/**
- * @brief Initializes s @p Mutex structure.
- *
- * @param[out] mp pointer to a @p Mutex structure
- *
- * @init
- */
-void chMtxInit(Mutex *mp) {
-
- chDbgCheck(mp != NULL, "chMtxInit");
-
- queue_init(&mp->m_queue);
- mp->m_owner = NULL;
-}
-
-/**
- * @brief Locks the specified mutex.
- * @post The mutex is locked and inserted in the per-thread stack of owned
- * mutexes.
- *
- * @param[in] mp pointer to the @p Mutex structure
- *
- * @api
- */
-void chMtxLock(Mutex *mp) {
-
- chSysLock();
-
- chMtxLockS(mp);
-
- chSysUnlock();
-}
-
-/**
- * @brief Locks the specified mutex.
- * @post The mutex is locked and inserted in the per-thread stack of owned
- * mutexes.
- *
- * @param[in] mp pointer to the @p Mutex structure
- *
- * @sclass
- */
-void chMtxLockS(Mutex *mp) {
- Thread *ctp = currp;
-
- chDbgCheckClassS();
- chDbgCheck(mp != NULL, "chMtxLockS");
-
- /* Is the mutex already locked? */
- if (mp->m_owner != NULL) {
- /* Priority inheritance protocol; explores the thread-mutex dependencies
- boosting the priority of all the affected threads to equal the priority
- of the running thread requesting the mutex.*/
- Thread *tp = mp->m_owner;
- /* Does the running thread have higher priority than the mutex
- owning thread? */
- while (tp->p_prio < ctp->p_prio) {
- /* Make priority of thread tp match the running thread's priority.*/
- tp->p_prio = ctp->p_prio;
- /* The following states need priority queues reordering.*/
- switch (tp->p_state) {
- case THD_STATE_WTMTX:
- /* Re-enqueues the mutex owner with its new priority.*/
- prio_insert(dequeue(tp), (ThreadsQueue *)tp->p_u.wtobjp);
- tp = ((Mutex *)tp->p_u.wtobjp)->m_owner;
- continue;
-#if CH_USE_CONDVARS | \
- (CH_USE_SEMAPHORES && CH_USE_SEMAPHORES_PRIORITY) | \
- (CH_USE_MESSAGES && CH_USE_MESSAGES_PRIORITY)
-#if CH_USE_CONDVARS
- case THD_STATE_WTCOND:
-#endif
-#if CH_USE_SEMAPHORES && CH_USE_SEMAPHORES_PRIORITY
- case THD_STATE_WTSEM:
-#endif
-#if CH_USE_MESSAGES && CH_USE_MESSAGES_PRIORITY
- case THD_STATE_SNDMSGQ:
-#endif
- /* Re-enqueues tp with its new priority on the queue.*/
- prio_insert(dequeue(tp), (ThreadsQueue *)tp->p_u.wtobjp);
- break;
-#endif
- case THD_STATE_READY:
-#if CH_DBG_ENABLE_ASSERTS
- /* Prevents an assertion in chSchReadyI().*/
- tp->p_state = THD_STATE_CURRENT;
-#endif
- /* Re-enqueues tp with its new priority on the ready list.*/
- chSchReadyI(dequeue(tp));
- break;
- }
- break;
- }
- /* Sleep on the mutex.*/
- prio_insert(ctp, &mp->m_queue);
- ctp->p_u.wtobjp = mp;
- chSchGoSleepS(THD_STATE_WTMTX);
- /* It is assumed that the thread performing the unlock operation assigns
- the mutex to this thread.*/
- chDbgAssert(mp->m_owner == ctp, "chMtxLockS(), #1", "not owner");
- chDbgAssert(ctp->p_mtxlist == mp, "chMtxLockS(), #2", "not owned");
- }
- else {
- /* It was not owned, inserted in the owned mutexes list.*/
- mp->m_owner = ctp;
- mp->m_next = ctp->p_mtxlist;
- ctp->p_mtxlist = mp;
- }
-}
-
-/**
- * @brief Tries to lock a mutex.
- * @details This function attempts to lock a mutex, if the mutex is already
- * locked by another thread then the function exits without waiting.
- * @post The mutex is locked and inserted in the per-thread stack of owned
- * mutexes.
- * @note This function does not have any overhead related to the
- * priority inheritance mechanism because it does not try to
- * enter a sleep state.
- *
- * @param[in] mp pointer to the @p Mutex structure
- * @return The operation status.
- * @retval TRUE if the mutex has been successfully acquired
- * @retval FALSE if the lock attempt failed.
- *
- * @api
- */
-bool_t chMtxTryLock(Mutex *mp) {
- bool_t b;
-
- chSysLock();
-
- b = chMtxTryLockS(mp);
-
- chSysUnlock();
- return b;
-}
-
-/**
- * @brief Tries to lock a mutex.
- * @details This function attempts to lock a mutex, if the mutex is already
- * taken by another thread then the function exits without waiting.
- * @post The mutex is locked and inserted in the per-thread stack of owned
- * mutexes.
- * @note This function does not have any overhead related to the
- * priority inheritance mechanism because it does not try to
- * enter a sleep state.
- *
- * @param[in] mp pointer to the @p Mutex structure
- * @return The operation status.
- * @retval TRUE if the mutex has been successfully acquired
- * @retval FALSE if the lock attempt failed.
- *
- * @sclass
- */
-bool_t chMtxTryLockS(Mutex *mp) {
-
- chDbgCheckClassS();
- chDbgCheck(mp != NULL, "chMtxTryLockS");
-
- if (mp->m_owner != NULL)
- return FALSE;
- mp->m_owner = currp;
- mp->m_next = currp->p_mtxlist;
- currp->p_mtxlist = mp;
- return TRUE;
-}
-
-/**
- * @brief Unlocks the next owned mutex in reverse lock order.
- * @pre The invoking thread <b>must</b> have at least one owned mutex.
- * @post The mutex is unlocked and removed from the per-thread stack of
- * owned mutexes.
- *
- * @return A pointer to the unlocked mutex.
- *
- * @api
- */
-Mutex *chMtxUnlock(void) {
- Thread *ctp = currp;
- Mutex *ump, *mp;
-
- chSysLock();
- chDbgAssert(ctp->p_mtxlist != NULL,
- "chMtxUnlock(), #1",
- "owned mutexes list empty");
- chDbgAssert(ctp->p_mtxlist->m_owner == ctp,
- "chMtxUnlock(), #2",
- "ownership failure");
- /* Removes the top Mutex from the Thread's owned mutexes list and marks it
- as not owned.*/
- ump = ctp->p_mtxlist;
- ctp->p_mtxlist = ump->m_next;
- /* If a thread is waiting on the mutex then the fun part begins.*/
- if (chMtxQueueNotEmptyS(ump)) {
- Thread *tp;
-
- /* Recalculates the optimal thread priority by scanning the owned
- mutexes list.*/
- tprio_t newprio = ctp->p_realprio;
- mp = ctp->p_mtxlist;
- while (mp != NULL) {
- /* If the highest priority thread waiting in the mutexes list has a
- greater priority than the current thread base priority then the final
- priority will have at least that priority.*/
- if (chMtxQueueNotEmptyS(mp) && (mp->m_queue.p_next->p_prio > newprio))
- newprio = mp->m_queue.p_next->p_prio;
- mp = mp->m_next;
- }
- /* Assigns to the current thread the highest priority among all the
- waiting threads.*/
- ctp->p_prio = newprio;
- /* Awakens the highest priority thread waiting for the unlocked mutex and
- assigns the mutex to it.*/
- tp = fifo_remove(&ump->m_queue);
- ump->m_owner = tp;
- ump->m_next = tp->p_mtxlist;
- tp->p_mtxlist = ump;
- chSchWakeupS(tp, RDY_OK);
- }
- else
- ump->m_owner = NULL;
- chSysUnlock();
- return ump;
-}
-
-/**
- * @brief Unlocks the next owned mutex in reverse lock order.
- * @pre The invoking thread <b>must</b> have at least one owned mutex.
- * @post The mutex is unlocked and removed from the per-thread stack of
- * owned mutexes.
- * @post This function does not reschedule so a call to a rescheduling
- * function must be performed before unlocking the kernel.
- *
- * @return A pointer to the unlocked mutex.
- *
- * @sclass
- */
-Mutex *chMtxUnlockS(void) {
- Thread *ctp = currp;
- Mutex *ump, *mp;
-
- chDbgCheckClassS();
- chDbgAssert(ctp->p_mtxlist != NULL,
- "chMtxUnlockS(), #1",
- "owned mutexes list empty");
- chDbgAssert(ctp->p_mtxlist->m_owner == ctp,
- "chMtxUnlockS(), #2",
- "ownership failure");
-
- /* Removes the top Mutex from the owned mutexes list and marks it as not
- owned.*/
- ump = ctp->p_mtxlist;
- ctp->p_mtxlist = ump->m_next;
- /* If a thread is waiting on the mutex then the fun part begins.*/
- if (chMtxQueueNotEmptyS(ump)) {
- Thread *tp;
-
- /* Recalculates the optimal thread priority by scanning the owned
- mutexes list.*/
- tprio_t newprio = ctp->p_realprio;
- mp = ctp->p_mtxlist;
- while (mp != NULL) {
- /* If the highest priority thread waiting in the mutexes list has a
- greater priority than the current thread base priority then the final
- priority will have at least that priority.*/
- if (chMtxQueueNotEmptyS(mp) && (mp->m_queue.p_next->p_prio > newprio))
- newprio = mp->m_queue.p_next->p_prio;
- mp = mp->m_next;
- }
- ctp->p_prio = newprio;
- /* Awakens the highest priority thread waiting for the unlocked mutex and
- assigns the mutex to it.*/
- tp = fifo_remove(&ump->m_queue);
- ump->m_owner = tp;
- ump->m_next = tp->p_mtxlist;
- tp->p_mtxlist = ump;
- chSchReadyI(tp);
- }
- else
- ump->m_owner = NULL;
- return ump;
-}
-
-/**
- * @brief Unlocks all the mutexes owned by the invoking thread.
- * @post The stack of owned mutexes is emptied and all the found
- * mutexes are unlocked.
- * @note This function is <b>MUCH MORE</b> efficient than releasing the
- * mutexes one by one and not just because the call overhead,
- * this function does not have any overhead related to the priority
- * inheritance mechanism.
- *
- * @api
- */
-void chMtxUnlockAll(void) {
- Thread *ctp = currp;
-
- chSysLock();
- if (ctp->p_mtxlist != NULL) {
- do {
- Mutex *ump = ctp->p_mtxlist;
- ctp->p_mtxlist = ump->m_next;
- if (chMtxQueueNotEmptyS(ump)) {
- Thread *tp = fifo_remove(&ump->m_queue);
- ump->m_owner = tp;
- ump->m_next = tp->p_mtxlist;
- tp->p_mtxlist = ump;
- chSchReadyI(tp);
- }
- else
- ump->m_owner = NULL;
- } while (ctp->p_mtxlist != NULL);
- ctp->p_prio = ctp->p_realprio;
- chSchRescheduleS();
- }
- chSysUnlock();
-}
-
-#endif /* CH_USE_MUTEXES */
-
-/** @} */
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