/**
* @brief Locks the specified mutex.
*
* @param[in] mp pointer to the @p Mutex structure
*/
void chMtxLockS(Mutex *mp) {
Thread *ctp = currp;
chDbgCheck(mp != NULL, "chMtxLockS");
/* Ia 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
ownning 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_PRIORITY | CH_USE_MESSAGES_PRIORITY
#if CH_USE_CONDVARS
case THD_STATE_WTCOND:
#endif
#if CH_USE_SEMAPHORES_PRIORITY
case THD_STATE_WTSEM:
#endif
#if CH_USE_MESSAGES_PRIORITY
case THD_STATE_SNDMSG:
#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:
/* Re-enqueues tp with its new priority on the ready list.*/
chSchReadyI(dequeue(tp));
}
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 Waits on the condition variable releasing the mutex lock.
* @details Releases the currently owned mutex, waits on the condition
* variable, and finally acquires the mutex again. All the sequence
* is performed atomically.
* @pre The invoking thread <b>must</b> have at least one owned mutex.
* @pre The configuration option @p CH_USE_CONDVARS_TIMEOUT must be enabled
* in order to use this function.
* @post Exiting the function because a timeout does not re-acquire the
* mutex, the mutex ownership is lost.
*
* @param[in] cp pointer to the @p CondVar structure
* @param[in] time the number of ticks before the operation timeouts, the
* special values are handled as follow:
* - @a TIME_INFINITE no timeout.
* - @a TIME_IMMEDIATE this value is not allowed.
* .
* @return A message specifying how the invoking thread has been
* released from the condition variable.
* @retval RDY_OK if the condvar has been signaled using
* @p chCondSignal().
* @retval RDY_RESET if the condvar has been signaled using
* @p chCondBroadcast().
* @retval RDY_TIMEOUT if the condvar has not been signaled within the
* specified timeout.
*
* @sclass
*/
msg_t chCondWaitTimeoutS(CondVar *cp, systime_t time) {
Mutex *mp;
msg_t msg;
chDbgCheck((cp != NULL) && (time != TIME_IMMEDIATE), "chCondWaitTimeoutS");
chDbgAssert(currp->p_mtxlist != NULL,
"chCondWaitTimeoutS(), #1",
"not owning a mutex");
mp = chMtxUnlockS();
currp->p_u.wtobjp = cp;
prio_insert(currp, &cp->c_queue);
msg = chSchGoSleepTimeoutS(THD_STATE_WTCOND, time);
if (msg != RDY_TIMEOUT)
chMtxLockS(mp);
return msg;
}
/**
* @brief Waits on the condition variable releasing the mutex lock.
* @details Releases the currently owned mutex, waits on the condition
* variable, and finally acquires the mutex again. All the sequence
* is performed atomically.
* @pre The invoking thread <b>must</b> have at least one owned mutex.
*
* @param[in] cp pointer to the @p CondVar structure
* @return A message specifying how the invoking thread has been
* released from the condition variable.
* @retval RDY_OK if the condvar has been signaled using
* @p chCondSignal().
* @retval RDY_RESET if the condvar has been signaled using
* @p chCondBroadcast().
*
* @sclass
*/
msg_t chCondWaitS(CondVar *cp) {
Thread *ctp = currp;
Mutex *mp;
msg_t msg;
chDbgCheck(cp != NULL, "chCondWaitS");
chDbgAssert(ctp->p_mtxlist != NULL,
"chCondWaitS(), #1",
"not owning a mutex");
mp = chMtxUnlockS();
ctp->p_u.wtobjp = cp;
prio_insert(ctp, &cp->c_queue);
chSchGoSleepS(THD_STATE_WTCOND);
msg = ctp->p_u.rdymsg;
chMtxLockS(mp);
return msg;
}
