Fix atexit() function being called twice

git-svn-id: https://nuttx.svn.sourceforge.net/svnroot/nuttx/trunk@4644 7fd9a85b-ad96-42d3-883c-3090e2eb8679

2 files changed, 36 insertions, 0 deletions

diff --git a/nuttx/sched/task_delete.c b/nuttx/sched/task_delete.c
index 4cd2b3ba7..e5244a0b8 100644
--- a/nuttx/sched/task_delete.c
+++ b/nuttx/sched/task_delete.c
@@ -83,6 +83,21 @@
  *   This function causes a specified task to cease to exist. Its  stack and
  *   TCB will be deallocated.  This function is the companion to task_create().
  *
+ *   The logic in this function only deletes non-running tasks.  If the 'pid'
+ *   parameter refers to to the currently runing task, then processing is
+ *   redirected to exit().
+ *
+ *   Control will still be returned to task_delete() after the exit() logic
+ *   finishes.  In fact, this function is the final function called all task
+ *   termination sequences.  Here are all possible exit scenarios:
+ *
+ *   - pthread_exit().  Calls exit()
+ *   - exit(). Calls _exit()
+ *   - _exit().  Calls task_deletecurrent() making the currently running task
+ *     non-running then calls task_delete() to terminate the non-running
+ *     task.
+ *   - task_delete()
+ *
  * Inputs:
  *   pid - The task ID of the task to delete.  A pid of zero
  *         signifies the calling task.
@@ -145,6 +160,9 @@ int task_delete(pid_t pid)
    * this as early as possible so that higher level clean-up logic
    * can run in a healthy tasking environment.
    *
+   * In the case where the task exits via exit(), task_exithook()
+   * may be called twice.
+   *
    * I suppose EXIT_SUCCESS is an appropriate return value???
    */
 
diff --git a/nuttx/sched/task_exithook.c b/nuttx/sched/task_exithook.c
index 44073165a..e160a1cb3 100644
--- a/nuttx/sched/task_exithook.c
+++ b/nuttx/sched/task_exithook.c
@@ -114,14 +114,32 @@ void task_exithook(FAR _TCB *tcb, int status)
 #ifdef CONFIG_SCHED_ATEXIT
   if (tcb->atexitfunc)
     {
+      /* Call the atexit function */
+
       (*tcb->atexitfunc)();
+
+      /* Nullify the atexit function.  task_exithook may be called more then
+       * once in most task exit scenarios.  Nullifying the atext function
+       * pointer will assure that the callback is performed only once.
+       */
+
+      tcb->atexitfunc = NULL;
     }
 #endif
 
 #ifdef CONFIG_SCHED_ONEXIT
   if (tcb->onexitfunc)
     {
+      /* Call the on_exit function */
+
       (*tcb->onexitfunc)(status, tcb->onexitarg);
+
+      /* Nullify the on_exit function.  task_exithook may be called more then
+       * once in most task exit scenarios.  Nullifying the on_exit function
+       * pointer will assure that the callback is performed only once.
+       */
+
+      tcb->onexitfunc = NULL;
     }
 #endif