int pthread_completejoin(pid_t pid, FAR void *exit_value)
{
FAR struct task_group_s *group = task_getgroup(pid);
FAR struct join_s *pjoin;
sinfo("pid=%d exit_value=%p group=%p\n", pid, exit_value, group);
DEBUGASSERT(group);
/* First, find thread's structure in the private data set. */
(void)pthread_takesemaphore(&group->tg_joinsem);
pjoin = pthread_findjoininfo(group, pid);
if (!pjoin)
{
serr("ERROR: Could not find join info, pid=%d\n", pid);
(void)pthread_givesemaphore(&group->tg_joinsem);
return ERROR;
}
else
{
bool waiters;
/* Save the return exit value in the thread structure. */
pjoin->terminated = true;
pjoin->exit_value = exit_value;
/* Notify waiters of the availability of the exit value */
waiters = pthread_notifywaiters(pjoin);
/* If there are no waiters and if the thread is marked as detached.
* then discard the join information now. Otherwise, the pthread
* join logic will call pthread_destroyjoin() when all of the threads
* have sampled the exit value.
*/
if (!waiters && pjoin->detached)
{
pthread_destroyjoin(group, pjoin);
}
/* Giving the following semaphore will allow the waiters
* to call pthread_destroyjoin.
*/
(void)pthread_givesemaphore(&group->tg_joinsem);
}
return OK;
}
int pthread_detach(pthread_t thread)
{
FAR struct tcb_s *rtcb = (FAR struct tcb_s *)g_readytorun.head;
FAR struct task_group_s *group = rtcb->group;
FAR struct join_s *pjoin;
int ret;
sdbg("Thread=%d group=%p\n", thread, group);
DEBUGASSERT(group);
/* Find the entry associated with this pthread. */
(void)pthread_takesemaphore(&group->tg_joinsem);
pjoin = pthread_findjoininfo(group, (pid_t)thread);
if (!pjoin)
{
sdbg("Could not find thread entry\n");
ret = EINVAL;
}
else
{
/* Has the thread already terminated? */
if (pjoin->terminated)
{
/* YES.. just remove the thread entry. */
pthread_destroyjoin(group, pjoin);
}
else
{
/* NO.. Just mark the thread as detached. It
* will be removed and deallocated when the
* thread exits
*/
pjoin->detached = true;
}
/* Either case is successful */
ret = OK;
}
(void)pthread_givesemaphore(&group->tg_joinsem);
sdbg("Returning %d\n", ret);
return ret;
}
int pthread_completejoin(pid_t pid, FAR void *exit_value)
{
FAR join_t *pjoin;
sdbg("process_id=%d exit_value=%p\n", pid, exit_value);
/* First, find thread's structure in the private data set. */
(void)pthread_takesemaphore(&g_join_semaphore);
pjoin = pthread_findjoininfo(pid);
if (!pjoin)
{
(void)pthread_givesemaphore(&g_join_semaphore);
return ERROR;
}
else
{
bool waiters;
/* Save the return exit value in the thread structure. */
pjoin->terminated = true;
pjoin->exit_value = exit_value;
/* Notify waiters of the availability of the exit value */
waiters = pthread_notifywaiters(pjoin);
/* If there are no waiters and if the thread is marked as detached.
* then discard the join information now. Otherwise, the pthread
* join logic will call pthread_destroyjoin() when all of the threads
* have sampled the exit value.
*/
if (!waiters && pjoin->detached)
{
pthread_destroyjoin(pjoin);
}
/* Giving the following semaphore will allow the waiters
* to call pthread_destroyjoin.
*/
(void)pthread_givesemaphore(&g_join_semaphore);
}
return OK;
}
static void *findjoininfo_callback(void *param)
{
int ret_chk = 0;
FAR struct task_group_s *group;
FAR struct join_s *st_pjoininfo;
g_bpthreadcallback = true;
pid_t pid = getpid();
group = task_getgroup(pid);
st_pjoininfo = pthread_findjoininfo(group, pid);
if (st_pjoininfo == NULL) {
printf("pthread_findjoininfo: Fail \n");
g_bpthreadcallback = false;
goto err;
}
ret_chk = pthread_equal((pid_t)st_pjoininfo->thread, pid);
if (ret_chk != 1) {
printf("tc_pthread_pthread_findjoininfo_destroyjoin pthread_equal fail\n");
g_bpthreadcallback = false;
goto err;
}
pthread_destroyjoin(group, st_pjoininfo);
st_pjoininfo = pthread_findjoininfo(group, pid);
if (st_pjoininfo != NULL) {
printf("pthread_findjoininfo: st_pjoininfo Fail \n");
g_bpthreadcallback = false;
goto err;
}
err:
pthread_exit(NULL);
return NULL;
}
int pthread_join(pthread_t thread, FAR pthread_addr_t *pexit_value)
{
FAR struct tcb_s *rtcb = this_task();
FAR struct task_group_s *group = rtcb->group;
FAR struct join_s *pjoin;
int ret;
sdbg("thread=%d group=%p\n", thread, group);
DEBUGASSERT(group);
/* First make sure that this is not an attempt to join to
* ourself.
*/
if ((pid_t)thread == getpid())
{
return EDEADLK;
}
/* Make sure no other task is mucking with the data structures
* while we are performing the following operations. NOTE:
* we can be also sure that pthread_exit() will not execute
* because it will also attempt to get this semaphore.
*/
(void)pthread_takesemaphore(&group->tg_joinsem);
/* Find the join information associated with this thread.
* This can fail for one of three reasons: (1) There is no
* thread associated with 'thread,' (2) the thread is a task
* and does not have join information, or (3) the thread
* was detached and has exited.
*/
pjoin = pthread_findjoininfo(group, (pid_t)thread);
if (!pjoin)
{
/* Determine what kind of error to return */
FAR struct tcb_s *tcb = sched_gettcb((pthread_t)thread);
sdbg("Could not find thread data\n");
/* Case (1) or (3) -- we can't tell which. Assume (3) */
if (!tcb)
{
ret = ESRCH;
}
/* The thread is still active but has no join info. In that
* case, it must be a task and not a pthread.
*/
else
{
ret = EINVAL;
}
(void)pthread_givesemaphore(&group->tg_joinsem);
}
else
{
/* We found the join info structure. Increment for the reference
* to the join structure that we have. This will keep things
* stable for we have to do
*/
sched_lock();
pjoin->crefs++;
/* Check if the thread is still running. If not, then things are
* simpler. There are still race conditions to be concerned with.
* For example, there could be multiple threads executing in the
* 'else' block below when we enter!
*/
if (pjoin->terminated)
{
sdbg("Thread has terminated\n");
/* Get the thread exit value from the terminated thread. */
if (pexit_value)
{
sdbg("exit_value=0x%p\n", pjoin->exit_value);
*pexit_value = pjoin->exit_value;
}
}
else
{
sdbg("Thread is still running\n");
/* Relinquish the data set semaphore. Since pre-emption is
* disabled, we can be certain that no task has the
* opportunity to run between the time we relinquish the
* join semaphore and the time that we wait on the thread exit
* semaphore.
*/
(void)pthread_givesemaphore(&group->tg_joinsem);
/* Take the thread's thread exit semaphore. We will sleep here
* until the thread exits. We need to exercise caution because
* there could be multiple threads waiting here for the same
* pthread to exit.
*/
(void)pthread_takesemaphore(&pjoin->exit_sem);
/* The thread has exited! Get the thread exit value */
if (pexit_value)
{
*pexit_value = pjoin->exit_value;
sdbg("exit_value=0x%p\n", pjoin->exit_value);
}
/* Post the thread's data semaphore so that the exiting thread
* will know that we have received the data.
*/
(void)pthread_givesemaphore(&pjoin->data_sem);
/* Retake the join semaphore, we need to hold this when
* pthread_destroyjoin is called.
*/
(void)pthread_takesemaphore(&group->tg_joinsem);
}
/* Pre-emption is okay now. The logic still cannot be re-entered
* because we hold the join semaphore
*/
sched_unlock();
/* Release our reference to the join structure and, if the reference
* count decrements to zero, deallocate the join structure.
*/
if (--pjoin->crefs <= 0)
{
(void)pthread_destroyjoin(group, pjoin);
}
(void)pthread_givesemaphore(&group->tg_joinsem);
ret = OK;
}
sdbg("Returning %d\n", ret);
return ret;
}
int pthread_mutex_destroy(FAR pthread_mutex_t *mutex)
{
struct tcb_s *ptcb;
struct join_s *pjoin = NULL;
int ret = EINVAL;
int status;
svdbg("mutex=0x%p\n", mutex);
DEBUGASSERT(mutex != NULL);
if (mutex != NULL) {
/* Make sure the semaphore is stable while we make the following checks */
sched_lock();
/* Is the semaphore available? */
if (mutex->pid >= 0) {
DEBUGASSERT(mutex->pid != 0); /* < 0: available, >0 owned, ==0 error */
/* No.. Verify that the PID still exists. We may be destroying
* the mutex after cancelling a pthread and the mutex may have
* been in a bad state owned by the dead pthread. NOTE: The
* following behavior is unspecified for pthread_mutex_destroy()
* (see pthread_mutex_consistent()).
*
* If the holding thread is still valid, then we should be able to
* map its PID to the underlying TCB. That is what sched_gettcb()
* does.
*/
ptcb = sched_gettcb(mutex->pid);
if (ptcb && ((ptcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_PTHREAD)) {
pjoin = pthread_findjoininfo(ptcb->group, ptcb->pid);
}
/* In some cases, pthread_mutex_destroy can be executed on middle of
* exiting pthread which holds mutex. The sched_releasepid() updates
* g_pidhash list to NULL by calling _exit() from pthread_exit().
* But, before calling it, pthread_exit() calls pthread_completejoin().
* It gives semaphore of pthread_join before executing _exit().
* It might cause user call pthread_mutex_destroy before updating scheduler.
* Checking pjoin structure and terminated element helps to check
* whether pthread which holds mutex is exiting or not.
*/
if (ptcb == NULL || \
(((ptcb->flags & TCB_FLAG_TTYPE_MASK) == TCB_FLAG_TTYPE_PTHREAD) && (pjoin == NULL || pjoin->terminated == true))) {
/* The thread associated with the PID no longer exists */
mutex->pid = -1;
/* Reset the semaphore. If threads are were on this
* semaphore, then this will awakened them and make
* destruction of the semaphore impossible here.
*/
status = sem_reset((FAR sem_t *)&mutex->sem, 1);
if (status < 0) {
ret = -status;
}
/* Check if the reset caused some other thread to lock the
* mutex.
*/
else if (mutex->pid != -1) {
/* Yes.. then we cannot destroy the mutex now. */
ret = EBUSY;
}
/* Destroy the underlying semaphore */
else {
status = sem_destroy((FAR sem_t *)&mutex->sem);
ret = (status != OK) ? get_errno() : OK;
}
} else {
ret = EBUSY;
}
} else {
/* Destroy the semaphore
*
* REVISIT: What if there are threads waiting on the semaphore?
* Perhaps this logic should all sem_reset() first?
*/
status = sem_destroy((sem_t *)&mutex->sem);
ret = ((status != OK) ? get_errno() : OK);
}
sched_unlock();
}
svdbg("Returning %d\n", ret);
return ret;
}
