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nuttx/sched/task/task_exithook.c

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/****************************************************************************
* sched/task/task_exithook.c
*
* Copyright (C) 2011-2013, 2015 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <debug.h>
#include <errno.h>
#include <nuttx/sched.h>
#include <nuttx/fs/fs.h>
#include "sched/sched.h"
#include "group/group.h"
#include "signal/signal.h"
#include "task/task.h"
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Name: task_atexit
*
* Description:
* Call any registered atexit function(s)
*
****************************************************************************/
#if defined(CONFIG_SCHED_ATEXIT) && !defined(CONFIG_SCHED_ONEXIT)
static inline void task_atexit(FAR struct tcb_s *tcb)
{
FAR struct task_group_s *group = tcb->group;
/* Make sure that we have not already left the group. Only the final
* exiting thread in the task group should trigger the atexit()
* callbacks.
*/
if (group && group->tg_nmembers == 1)
{
#if defined(CONFIG_SCHED_ATEXIT_MAX) && CONFIG_SCHED_ATEXIT_MAX > 1
int index;
/* Call each atexit function in reverse order of registration atexit()
* functions are registered from lower to higher array indices; they
* must be called in the reverse order of registration when the task
* group exits, i.e., from higher to lower indices.
*/
for (index = CONFIG_SCHED_ATEXIT_MAX-1; index >= 0; index--)
{
if (group->tg_atexitfunc[index])
{
/* Call the atexit function */
(*group->tg_atexitfunc[index])();
/* Nullify the atexit function to prevent its reuse. */
group->tg_atexitfunc[index] = NULL;
}
}
#else
if (group->tg_atexitfunc)
{
/* Call the atexit function */
(*group->tg_atexitfunc)();
/* Nullify the atexit function to prevent its reuse. */
group->tg_atexitfunc = NULL;
}
#endif
}
}
#else
# define task_atexit(tcb)
#endif
/****************************************************************************
* Name: task_onexit
*
* Description:
* Call any registered on_exit function(s)
*
****************************************************************************/
#ifdef CONFIG_SCHED_ONEXIT
static inline void task_onexit(FAR struct tcb_s *tcb, int status)
{
FAR struct task_group_s *group = tcb->group;
/* Make sure that we have not already left the group. Only the final
* exiting thread in the task group should trigger the atexit()
* callbacks.
*/
if (group && group->tg_nmembers == 1)
{
#if defined(CONFIG_SCHED_ONEXIT_MAX) && CONFIG_SCHED_ONEXIT_MAX > 1
int index;
/* Call each on_exit function in reverse order of registration.
* on_exit() functions are registered from lower to higher array
* indices; they must be called in the reverse order of registration
* when the task group exits, i.e., from higher to lower indices.
*/
for (index = CONFIG_SCHED_ONEXIT_MAX-1; index >= 0; index--)
{
if (group->tg_onexitfunc[index])
{
/* Call the on_exit function */
(*group->tg_onexitfunc[index])(status, group->tg_onexitarg[index]);
/* Nullify the on_exit function to prevent its reuse. */
group->tg_onexitfunc[index] = NULL;
}
}
#else
if (group->tg_onexitfunc)
{
/* Call the on_exit function */
(*group->tg_onexitfunc)(status, group->tg_onexitarg);
/* Nullify the on_exit function to prevent its reuse. */
group->tg_onexitfunc = NULL;
}
#endif
}
}
#else
# define task_onexit(tcb,status)
#endif
/****************************************************************************
* Name: task_exitstatus
*
* Description:
* Report exit status when main task of a task group exits
*
****************************************************************************/
#ifdef CONFIG_SCHED_CHILD_STATUS
static inline void task_exitstatus(FAR struct task_group_s *group, int status)
{
FAR struct child_status_s *child;
/* Check if the parent task group has suppressed retention of
* child exit status information.
*/
if ((group->tg_flags & GROUP_FLAG_NOCLDWAIT) == 0)
{
/* No.. Find the exit status entry for this task in the parent TCB */
child = group_findchild(group, getpid());
DEBUGASSERT(child);
if (child)
{
#ifndef HAVE_GROUP_MEMBERS
/* No group members? Save the exit status */
child->ch_status = status;
#endif
/* Save the exit status.. For the case of HAVE_GROUP_MEMBERS,
* the child status will be as exited until the last member
* of the task group exits.
*/
child->ch_status = status;
}
}
}
#else
# define task_exitstatus(group,status)
#endif /* CONFIG_SCHED_CHILD_STATUS */
/****************************************************************************
* Name: task_groupexit
*
* Description:
* Mark that the final thread of a child task group as exited.
*
****************************************************************************/
#ifdef CONFIG_SCHED_CHILD_STATUS
static inline void task_groupexit(FAR struct task_group_s *group)
{
FAR struct child_status_s *child;
/* Check if the parent task group has suppressed retention of child exit
* status information.
*/
if ((group->tg_flags & GROUP_FLAG_NOCLDWAIT) == 0)
{
/* No.. Find the exit status entry for this task in the parent TCB */
child = group_findchild(group, getpid());
DEBUGASSERT(child);
if (child)
{
/* Mark that all members of the child task group has exited */
child->ch_flags |= CHILD_FLAG_EXITED;
}
}
}
#else
# define task_groupexit(group)
#endif /* CONFIG_SCHED_CHILD_STATUS */
/****************************************************************************
* Name: task_sigchild
*
* Description:
* Send the SIGCHILD signal to the parent thread
*
****************************************************************************/
#ifdef CONFIG_SCHED_HAVE_PARENT
#ifdef HAVE_GROUP_MEMBERS
static inline void task_sigchild(gid_t pgid, FAR struct tcb_s *ctcb, int status)
{
FAR struct task_group_s *chgrp = ctcb->group;
FAR struct task_group_s *pgrp;
siginfo_t info;
DEBUGASSERT(chgrp);
/* Get the parent task group. It is possible that all of the members of
* the parent task group have exited. This would not be an error. In
* this case, the child task group has been orphaned.
*/
pgrp = group_findbygid(pgid);
if (!pgrp)
{
/* Set the task group ID to an invalid group ID. The dead parent
* task group ID could get reused some time in the future.
*/
chgrp->tg_pgid = INVALID_GROUP_ID;
return;
}
/* Save the exit status now if this is the main thread of the task group
* that is exiting. Only the exiting main task of a task group carries
* interpretable exit Check if this is the main task that is exiting.
*/
#ifndef CONFIG_DISABLE_PTHREAD
if ((ctcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_PTHREAD)
#endif
{
task_exitstatus(pgrp, status);
}
/* But only the final exiting thread in a task group, whatever it is,
* should generate SIGCHLD.
*/
if (chgrp->tg_nmembers == 1)
{
/* Mark that all of the threads in the task group have exited */
task_groupexit(pgrp);
/* Create the siginfo structure. We don't actually know the cause.
* That is a bug. Let's just say that the child task just exited
* for now.
*/
info.si_signo = SIGCHLD;
info.si_code = CLD_EXITED;
info.si_errno = OK;
info.si_value.sival_ptr = NULL;
#ifndef CONFIG_DISABLE_PTHREAD
info.si_pid = chgrp->tg_task;
#else
info.si_pid = ctcb->pid;
#endif
info.si_status = status;
/* Send the signal to one thread in the group */
(void)group_signal(pgrp, &info);
}
}
#else /* HAVE_GROUP_MEMBERS */
static inline void task_sigchild(FAR struct tcb_s *ptcb,
FAR struct tcb_s *ctcb, int status)
{
siginfo_t info;
/* If task groups are not supported then we will report SIGCHLD when the
* task exits. Unfortunately, there could still be threads in the group
* that are still running.
*/
#ifndef CONFIG_DISABLE_PTHREAD
if ((ctcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_PTHREAD)
#endif
{
#ifdef CONFIG_SCHED_CHILD_STATUS
/* Save the exit status now of the main thread */
task_exitstatus(ptcb->group, status);
#else /* CONFIG_SCHED_CHILD_STATUS */
/* Exit status is not retained. Just decrement the number of
* children from this parent.
*/
DEBUGASSERT(ptcb->group != NULL && ptcb->group->tg_nchildren > 0);
ptcb->group->tg_nchildren--;
#endif /* CONFIG_SCHED_CHILD_STATUS */
/* Create the siginfo structure. We don't actually know the cause.
* That is a bug. Let's just say that the child task just exited
* for now.
*/
info.si_signo = SIGCHLD;
info.si_code = CLD_EXITED;
info.si_errno = OK;
info.si_value.sival_ptr = NULL;
#ifndef CONFIG_DISABLE_PTHREAD
info.si_pid = ctcb->group->tg_task;
#else
info.si_pid = ctcb->pid;
#endif
info.si_status = status;
/* Send the signal. We need to use this internal interface so that we
* can provide the correct si_code value with the signal.
*/
(void)sig_tcbdispatch(ptcb, &info);
}
}
#endif /* HAVE_GROUP_MEMBERS */
#else /* CONFIG_SCHED_HAVE_PARENT */
# define task_sigchild(x,ctcb,status)
#endif /* CONFIG_SCHED_HAVE_PARENT */
/****************************************************************************
* Name: task_signalparent
*
* Description:
* Send the SIGCHILD signal to the parent task group
*
****************************************************************************/
#ifdef CONFIG_SCHED_HAVE_PARENT
static inline void task_signalparent(FAR struct tcb_s *ctcb, int status)
{
#ifdef HAVE_GROUP_MEMBERS
DEBUGASSERT(ctcb && ctcb->group);
/* Keep things stationary throughout the following */
sched_lock();
/* Send SIGCHLD to all members of the parent's task group */
task_sigchild(ctcb->group->tg_pgid, ctcb, status);
sched_unlock();
#else
FAR struct tcb_s *ptcb;
/* Keep things stationary throughout the following */
sched_lock();
/* Get the TCB of the receiving, parent task. We do this early to
* handle multiple calls to task_signalparent. ctcb->group->tg_ppid is
* set to an invalid value below and the following call will fail if we
* are called again.
*/
ptcb = sched_gettcb(ctcb->group->tg_ppid);
if (ptcb == NULL)
{
/* The parent no longer exists... bail */
sched_unlock();
return;
}
/* Send SIGCHLD to all members of the parent's task group */
task_sigchild(ptcb, ctcb, status);
/* Forget who our parent was */
ctcb->group->tg_ppid = INVALID_PROCESS_ID;
sched_unlock();
#endif
}
#else
# define task_signalparent(ctcb,status)
#endif
/****************************************************************************
* Name: task_exitwakeup
*
* Description:
* Wakeup any tasks waiting for this task to exit
*
****************************************************************************/
#if defined(CONFIG_SCHED_WAITPID) && !defined(CONFIG_SCHED_HAVE_PARENT)
static inline void task_exitwakeup(FAR struct tcb_s *tcb, int status)
{
FAR struct task_group_s *group = tcb->group;
/* Have we already left the group? */
if (group)
{
/* Only tasks (and kernel threads) return valid status. Record the
* exit status when the task exists. The group, however, may still
* be executing.
*/
#ifndef CONFIG_DISABLE_PTHREAD
if ((tcb->flags & TCB_FLAG_TTYPE_MASK) != TCB_FLAG_TTYPE_PTHREAD)
#endif
{
/* Report the exit status. We do not nullify tg_statloc here
* because we want to prevent other tasks from registering for
* the return status. There is only one task per task group,
* there for, this logic should execute exactly once in the
* lifetime of the task group.
*
* "If more than one thread is suspended in waitpid() awaiting
* termination of the same process, exactly one thread will
* return the process status at the time of the target process
* termination."
*
* Hmmm.. what do we return to the others?
*/
if (group->tg_statloc)
{
*group->tg_statloc = status << 8;
}
}
/* Is this the last thread in the group? */
if (group->tg_nmembers == 1)
{
/* Yes.. Wakeup any tasks waiting for this task to exit */
group->tg_statloc = NULL;
while (group->tg_exitsem.semcount < 0)
{
/* Wake up the thread */
sem_post(&group->tg_exitsem);
}
}
}
}
#else
# define task_exitwakeup(tcb, status)
#endif
/****************************************************************************
* Name: task_flushstreams
*
* Description:
* Flush all streams when the final thread of a group exits.
*
****************************************************************************/
#if CONFIG_NFILE_STREAMS > 0
static inline void task_flushstreams(FAR struct tcb_s *tcb)
{
FAR struct task_group_s *group = tcb->group;
/* Have we already left the group? Are we the last thread in the group? */
if (group && group->tg_nmembers == 1)
{
#if (defined(CONFIG_BUILD_PROTECTED) || defined(CONFIG_BUILD_KERNEL)) && \
defined(CONFIG_MM_KERNEL_HEAP)
(void)lib_flushall(tcb->group->tg_streamlist);
#else
(void)lib_flushall(&tcb->group->tg_streamlist);
#endif
}
}
#else
# define task_flushstreams(tcb)
#endif
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: task_exithook
*
* Description:
* This function implements some of the internal logic of exit() and
* task_delete(). This function performs some clean-up and other actions
* required when a task exits:
*
* - All open streams are flushed and closed.
* - All functions registered with atexit() and on_exit() are called, in
* the reverse order of their registration.
*
* When called from exit(), the tcb still resides at the head of the ready-
* to-run list. The following logic is safe because we will not be
* returning from the exit() call.
*
* When called from task_terminate() we are operating on a different thread;
* on the thread that called task_delete(). In this case, task_delete
* will have already removed the tcb from the ready-to-run list to prevent
* any further action on this task.
*
* nonblocking will be set true only when we are called from task_terminate()
* via _exit(). In that case, we must be careful to do nothing that can
* cause the cause the thread to block.
*
****************************************************************************/
void task_exithook(FAR struct tcb_s *tcb, int status, bool nonblocking)
{
/* Under certain conditions, task_exithook() can be called multiple times.
* A bit in the TCB was set the first time this function was called. If
* that bit is set, then just exit doing nothing more..
*/
if ((tcb->flags & TCB_FLAG_EXIT_PROCESSING) != 0)
{
return;
}
#if defined(CONFIG_SCHED_ATEXIT) || defined(CONFIG_SCHED_ONEXIT)
/* If exit function(s) were registered, call them now before we do any un-
* initialization.
*
* NOTES:
*
* 1. In the case of task_delete(), the exit function will *not* be called
* on the thread execution of the task being deleted! That is probably
* a bug.
* 2. We cannot call the exit functions if nonblocking is requested: These
* functions might block.
* 3. This function will only be called with with non-blocking == true
* only when called through _exit(). _exit() behaviors requires that
* the exit functions *not* be called.
*/
if (!nonblocking)
{
task_atexit(tcb);
/* Call any registered on_exit function(s) */
task_onexit(tcb, status);
}
#endif
/* If the task was terminated by another task, it may be in an unknown
* state. Make some feeble effort to recover the state.
*/
task_recover(tcb);
/* Send the SIGCHILD signal to the parent task group */
task_signalparent(tcb, status);
/* Wakeup any tasks waiting for this task to exit */
task_exitwakeup(tcb, status);
/* If this is the last thread in the group, then flush all streams (File
* descriptors will be closed when the TCB is deallocated).
*
* NOTES:
* 1. We cannot flush the buffered I/O if nonblocking is requested.
* that might cause this logic to block.
* 2. This function will only be called with with non-blocking == true
* only when called through _exit(). _exit() behavior does not
* require that the streams be flushed
*/
if (!nonblocking)
{
task_flushstreams(tcb);
}
#ifdef HAVE_TASK_GROUP
/* Leave the task group. Perhaps discarding any un-reaped child
* status (no zombies here!)
*/
group_leave(tcb);
#endif
#ifndef CONFIG_DISABLE_SIGNALS
/* Deallocate anything left in the TCB's queues */
sig_cleanup(tcb); /* Deallocate Signal lists */
#endif
/* This function can be re-entered in certain cases. Set a flag
* bit in the TCB to not that we have already completed this exit
* processing.
*/
tcb->flags |= TCB_FLAG_EXIT_PROCESSING;
}
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