Ejemplo n.º 1
0
void group_removechildren(FAR struct task_group_s *group)
{
	FAR struct child_status_s *curr;
	FAR struct child_status_s *next;

	/* Remove all child structures for the TCB and return them to the freelist  */

	for (curr = group->tg_children; curr; curr = next) {
		next = curr->flink;
		group_freechild(curr);
	}

	group->tg_children = NULL;
	group_dumpchildren(group, "group_removechildren");
}
Ejemplo n.º 2
0
int task_reparent(pid_t ppid, pid_t chpid)
{
#ifdef CONFIG_SCHED_CHILD_STATUS
  FAR struct child_status_s *child;
#endif
  FAR struct task_group_s *chgrp;
  FAR struct task_group_s *ogrp;
  FAR struct task_group_s *pgrp;
  struct tcb_s *tcb;
  gid_t ogid;
  gid_t pgid;
  irqstate_t flags;
  int ret;

  /* Disable interrupts so that nothing can change in the relatinoship of
   * the three task:  Child, current parent, and new parent.
   */

  flags = irqsave();

  /* Get the child tasks task group */

  tcb = sched_gettcb(chpid);
  if (!tcb)
    {
      ret = -ECHILD;
      goto errout_with_ints;
    }

  DEBUGASSERT(tcb->group);
  chgrp = tcb->group;

  /* Get the GID of the old parent task's task group (ogid) */

  ogid = chgrp->tg_pgid;

  /* Get the old parent task's task group (ogrp) */

  ogrp = group_findbygid(ogid);
  if (!ogrp)
    {
      ret = -ESRCH;
      goto errout_with_ints;
    }

  /* If new parent task's PID (ppid) is zero, then new parent is the
   * grandparent will be the new parent, i.e., the parent of the current
   * parent task.
   */

  if (ppid == 0)
    {
      /* Get the grandparent task's task group (pgrp) */

      pgid = ogrp->tg_pgid;
      pgrp = group_findbygid(pgid);
    }
  else
    {
      /* Get the new parent task's task group (pgrp) */

      tcb = sched_gettcb(ppid);
      if (!tcb)
        {
          ret = -ESRCH;
          goto errout_with_ints;
        }

      pgrp = tcb->group;
      pgid = pgrp->tg_gid;
    }

  if (!pgrp)
    {
      ret = -ESRCH;
      goto errout_with_ints;
    }

  /* Then reparent the child.  Notice that we don't actually change the
   * parent of the task. Rather, we change the parent task group for
   * all members of the child's task group.
   */

  chgrp->tg_pgid = pgid;

#ifdef CONFIG_SCHED_CHILD_STATUS
  /* Remove the child status entry from old parent task group */

  child = group_removechild(ogrp, chpid);
  if (child)
    {
      /* Has the new parent's task group supressed child exit status? */

      if ((pgrp->tg_flags && GROUP_FLAG_NOCLDWAIT) == 0)
        {
          /* No.. Add the child status entry to the new parent's task group */

          group_addchild(pgrp, child);
        }
      else
        {
          /* Yes.. Discard the child status entry */

          group_freechild(child);
        }

      /* Either case is a success */

      ret = OK;
    }
  else
    {
      /* This would not be an error if the original parent's task group has
       * suppressed child exit status.
       */

      ret = ((ogrp->tg_flags && GROUP_FLAG_NOCLDWAIT) == 0) ? -ENOENT : OK;
    }

#else /* CONFIG_SCHED_CHILD_STATUS */

  DEBUGASSERT(otcb->nchildren > 0);

  otcb->nchildren--;     /* The orignal parent now has one few children */
  ptcb->nchildren++;     /* The new parent has one additional child */
  ret = OK;

#endif /* CONFIG_SCHED_CHILD_STATUS */

errout_with_ints:
  irqrestore(flags);
  return ret;
}
Ejemplo n.º 3
0
int task_reparent(pid_t ppid, pid_t chpid)
{
#ifdef CONFIG_SCHED_CHILD_STATUS
  FAR struct child_status_s *child;
#endif
  struct tcb_s *ptcb;
  struct tcb_s *chtcb;
  struct tcb_s *otcb;
  pid_t opid;
  irqstate_t flags;
  int ret;

  /* Disable interrupts so that nothing can change in the relatinoship of
   * the three task:  Child, current parent, and new parent.
   */

  flags = irqsave();

  /* Get the child tasks TCB (chtcb) */

  chtcb = sched_gettcb(chpid);
  if (!chtcb)
    {
      ret = -ECHILD;
      goto errout_with_ints;
    }

  /* Get the PID of the child task's parent (opid) */

  opid = chtcb->ppid;

  /* Get the TCB of the child task's parent (otcb) */

  otcb = sched_gettcb(opid);
  if (!otcb)
    {
      ret = -ESRCH;
      goto errout_with_ints;
    }

  /* If new parent task's PID (ppid) is zero, then new parent is the
   * grandparent will be the new parent, i.e., the parent of the current
   * parent task.
   */

  if (ppid == 0)
    {
      ppid = otcb->ppid;
    }

  /* Get the new parent task's TCB (ptcb) */

  ptcb = sched_gettcb(ppid);
  if (!ptcb)
    {
      ret = -ESRCH;
      goto errout_with_ints;
    }

  /* Then reparent the child */

  chtcb->ppid = ppid;  /* The task specified by ppid is the new parent */

#ifdef CONFIG_SCHED_CHILD_STATUS
  /* Remove the child status entry from old parent TCB */

  child = group_removechild(otcb->group, chpid);
  if (child)
    {
      /* Has the new parent's task group supressed child exit status? */

      if ((ptcb->group->tg_flags && GROUP_FLAG_NOCLDWAIT) == 0)
        {
          /* No.. Add the child status entry to the new parent's task group */

          group_addchild(ptcb->group, child);
        }
      else
        {
          /* Yes.. Discard the child status entry */

          group_freechild(child);
        }

      /* Either case is a success */

      ret = OK;
    }
  else
    {
      /* This would not be an error if the original parent's task group has
       * suppressed child exit status.
       */

      ret = ((otcb->group->tg_flags && GROUP_FLAG_NOCLDWAIT) == 0) ? -ENOENT : OK;
    }

#else /* CONFIG_SCHED_CHILD_STATUS */

  DEBUGASSERT(otcb->nchildren > 0);

  otcb->nchildren--;     /* The orignal parent now has one few children */
  ptcb->nchildren++;     /* The new parent has one additional child */
  ret = OK;

#endif /* CONFIG_SCHED_CHILD_STATUS */

errout_with_ints:
  irqrestore(flags);
  return ret;
}
Ejemplo n.º 4
0
pid_t waitpid(pid_t pid, int *stat_loc, int options)
{
  FAR struct tcb_s *rtcb = this_task();
  FAR struct tcb_s *ctcb;
#ifdef CONFIG_SCHED_CHILD_STATUS
  FAR struct child_status_s *child;
  bool retains;
#endif
  FAR struct siginfo info;
  sigset_t set;
  int errcode;
  int ret;

  DEBUGASSERT(stat_loc);

  /* waitpid() is a cancellation point */

  (void)enter_cancellation_point();

  /* None of the options are supported */

#ifdef CONFIG_DEBUG_FEATURES
  if (options != 0)
    {
      set_errno(ENOSYS);
      leave_cancellation_point();
      return ERROR;
    }
#endif

  /* Create a signal set that contains only SIGCHLD */

  (void)sigemptyset(&set);
  (void)sigaddset(&set, SIGCHLD);

  /* Disable pre-emption so that nothing changes while the loop executes */

  sched_lock();

  /* Verify that this task actually has children and that the requested PID
   * is actually a child of this task.
   */

#ifdef CONFIG_SCHED_CHILD_STATUS
  /* Does this task retain child status? */

  retains = ((rtcb->group->tg_flags && GROUP_FLAG_NOCLDWAIT) == 0);

  if (rtcb->group->tg_children == NULL && retains)
    {
      errcode = ECHILD;
      goto errout_with_errno;
    }
  else if (pid != (pid_t)-1)
    {
      /* Get the TCB corresponding to this PID and make sure that the
       * thread it is our child.
       */

      ctcb = sched_gettcb(pid);

#ifdef HAVE_GROUP_MEMBERS
      if (ctcb == NULL || ctcb->group->tg_pgid != rtcb->group->tg_gid)
#else
      if (ctcb == NULL || ctcb->group->tg_ppid != rtcb->pid)
#endif
        {
          errcode = ECHILD;
          goto errout_with_errno;
        }

      /* Does this task retain child status? */

      if (retains)
        {
          /* Check if this specific pid has allocated child status? */

          if (group_findchild(rtcb->group, pid) == NULL)
            {
              errcode = ECHILD;
              goto errout_with_errno;
            }
        }
    }

#else /* CONFIG_SCHED_CHILD_STATUS */

  if (rtcb->group->tg_nchildren == 0)
    {
      /* There are no children */

      errcode = ECHILD;
      goto errout_with_errno;
    }
  else if (pid != (pid_t)-1)
    {
      /* Get the TCB corresponding to this PID and make sure that the
       * thread it is our child.
       */

      ctcb = sched_gettcb(pid);

#ifdef HAVE_GROUP_MEMBERS
      if (ctcb == NULL || ctcb->group->tg_pgid != rtcb->group->tg_gid)
#else
      if (ctcb == NULL || ctcb->group->tg_ppid != rtcb->pid)
#endif
        {
          errcode = ECHILD;
          goto errout_with_errno;
        }
    }

#endif /* CONFIG_SCHED_CHILD_STATUS */

  /* Loop until the child that we are waiting for dies */

  for (; ; )
    {
#ifdef CONFIG_SCHED_CHILD_STATUS
      /* Check if the task has already died. Signals are not queued in
       * NuttX.  So a possibility is that the child has died and we
       * missed the death of child signal (we got some other signal
       * instead).
       */

      if (pid == (pid_t)-1)
        {
          /* We are waiting for any child, check if there are still
           * chilren.
           */

          DEBUGASSERT(!retains || rtcb->group->tg_children);
          if (retains && (child = group_exitchild(rtcb->group)) != NULL)
            {
              /* A child has exited.  Apparently we missed the signal.
               * Return the saved exit status.
               */

              /* The child has exited. Return the saved exit status */

              *stat_loc = child->ch_status << 8;

              /* Discard the child entry and break out of the loop */

              (void)group_removechild(rtcb->group, child->ch_pid);
              group_freechild(child);
              break;
            }
        }

      /* We are waiting for a specific PID. Does this task retain child status? */

      else if (retains)
        {
          /* Get the current status of the child task. */

          child = group_findchild(rtcb->group, pid);
          DEBUGASSERT(child);

          /* Did the child exit? */

          if ((child->ch_flags & CHILD_FLAG_EXITED) != 0)
            {
              /* The child has exited. Return the saved exit status */

              *stat_loc = child->ch_status << 8;

              /* Discard the child entry and break out of the loop */

              (void)group_removechild(rtcb->group, pid);
              group_freechild(child);
              break;
            }
        }
      else
        {
          /* We can use kill() with signal number 0 to determine if that
           * task is still alive.
           */

          ret = kill(pid, 0);
          if (ret < 0)
            {
              /* It is no longer running.  We know that the child task
               * was running okay when we started, so we must have lost
               * the signal.  In this case, we know that the task exit'ed,
               * but we do not know its exit status.  It would be better
               * to reported ECHILD than bogus status.
               */

              errcode = ECHILD;
              goto errout_with_errno;
            }
        }

#else  /* CONFIG_SCHED_CHILD_STATUS */

      /* Check if the task has already died. Signals are not queued in
       * NuttX.  So a possibility is that the child has died and we
       * missed the death of child signal (we got some other signal
       * instead).
       */

      if (rtcb->group->tg_nchildren == 0 ||
          (pid != (pid_t)-1 && (ret = kill(pid, 0)) < 0))
        {
          /* We know that the child task was running okay we stared,
           * so we must have lost the signal.  What can we do?
           * Let's return ECHILD.. that is at least informative.
           */

          errcode = ECHILD;
          goto errout_with_errno;
        }

#endif /* CONFIG_SCHED_CHILD_STATUS */

      /* Wait for any death-of-child signal */

      ret = sigwaitinfo(&set, &info);
      if (ret < 0)
        {
          goto errout_with_lock;
        }

      /* Was this the death of the thread we were waiting for? In the of
       * pid == (pid_t)-1, we are waiting for any child thread.
       */

      if (info.si_signo == SIGCHLD &&
         (pid == (pid_t)-1 || info.si_pid == pid))
        {
          /* Yes... return the status and PID (in the event it was -1) */

          *stat_loc = info.si_status << 8;
          pid = info.si_pid;
          break;
        }
    }

  leave_cancellation_point();
  sched_unlock();
  return (int)pid;

errout_with_errno:
  set_errno(errcode);

errout_with_lock:
  leave_cancellation_point();
  sched_unlock();
  return ERROR;
}