Mirrors_Framework/nuttx
1
0
Fork 0
mirror of https://github.com/apache/nuttx.git synced 2026-06-06 08:36:24 +08:00
Code Issues Actions Packages Projects Releases Wiki Activity

Correct a race condition in the pthread join logic. Sometimes the join structure was being deallocated while it was still needed.

Browse Source 
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@180 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo
2007-03-30 00:49:11 +00:00
parent 2a929796b9
commit f29250c671
7 changed files with 165 additions and 113 deletions
Download Patch File Download Diff File Expand all files Collapse all files
sched/pthread_completejoin.c
+66 -48
View File
@@ -65,16 +65,16 @@
************************************************************/
/************************************************************
* Function: pthread_destroyjoininfo
* Function: pthread_notifywaiters
*
* Description:
* Destroy a join_t structure. This must
* be done by the child thread at child thread destruction
* time.
* Notify all other threads waiting in phread join for this
* thread's exit data. This must be done by the child
* at child thread destruction time.
*
************************************************************/
static void pthread_destroyjoininfo(FAR join_t *pjoin)
static boolean pthread_notifywaiters(FAR join_t *pjoin)
{
int ntasks_waiting;
int status;
@@ -111,14 +111,9 @@ static void pthread_destroyjoininfo(FAR join_t *pjoin)
*/
(void)pthread_takesemaphore(&pjoin->data_sem);
(void)sem_destroy(&pjoin->data_sem);
return TRUE;
}
/* All of the joined threads have had received the exit value.
* Now we can destroy this thread's exit semaphore
*/
(void)sem_destroy(&pjoin->exit_sem);
return FALSE;
}
/************************************************************
@@ -148,7 +143,6 @@ static void pthread_destroyjoininfo(FAR join_t *pjoin)
int pthread_completejoin(pid_t pid, FAR void *exit_value)
{
FAR join_t *pjoin;
boolean detached = FALSE;
dbg("process_id=%d exit_value=%p\n", pid, exit_value);
@@ -164,48 +158,72 @@ int pthread_completejoin(pid_t pid, FAR void *exit_value)
}
else
{
/* Has the thread been marked as detached? */
boolean waiters;
/* Save the return exit value in the thread structure. */
pjoin->terminated = TRUE;
detached = pjoin->detached;
if (detached)
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)
{
dbg("Detaching\n");
/* If so, then remove the thread's structure from the private
* data set. After this point, no other thread can perform a join
* operation.
*/
(void)pthread_removejoininfo(pid);
(void)pthread_givesemaphore(&g_join_semaphore);
/* Destroy this thread data structure. */
pthread_destroyjoininfo(pjoin);
/* Deallocate the join entry if it was detached. */
sched_free((FAR void*)pjoin);
pthread_destroyjoin(pjoin);
}
/* No, then we can assume that some other thread is waiting for the join info */
/* Giving the following semaphore will allow the waiters
* to call pthread_destroyjoin.
*/
else
{
/* Save the return exit value in the thread structure. */
pjoin->exit_value = exit_value;
/* Destroy this thread data structure. */
pthread_destroyjoininfo(pjoin);
/* pthread_join may now access the thread entry structure. */
(void)pthread_givesemaphore(&g_join_semaphore);
}
(void)pthread_givesemaphore(&g_join_semaphore);
}
return OK;
}
/************************************************************
* Function: pthread_destroyjoin
*
* Description:
* This is called from pthread_completejoin if the join
* info was detached or from pthread_join when the last
* waiting thread has received the thread exit info.
*
* Or it may never be called if the join info was never
* detached or if no thread ever calls pthread_join. In
* case, there is a memory leak!
*
* Assumptions:
* The caller holds g_join_semaphore
*
************************************************************/
void pthread_destroyjoin(FAR join_t *pjoin)
{
int status;
dbg("pjoin=0x%p\n", pjoin);
/* Remove the join info from the set of joins */
(void)pthread_removejoininfo((pid_t)pjoin->thread);
/* Destroy its semaphores */
(void)sem_destroy(&pjoin->data_sem);
(void)sem_destroy(&pjoin->exit_sem);
/* And deallocate the pjoin structure */
sched_free(pjoin);
}