/**************************************************************************** * sched/task/task_exithook.c * * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. The * ASF licenses this file to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance with the * License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations * under the License. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include #include #include "sched/sched.h" #include "group/group.h" #include "signal/signal.h" #include "task/task.h" /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: nxtask_exitstatus * * Description: * Report exit status when main task of a task group exits * ****************************************************************************/ #ifdef CONFIG_SCHED_CHILD_STATUS static inline void nxtask_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_find_child(group, getpid()); if (child) { /* 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 nxtask_exitstatus(group,status) #endif /* CONFIG_SCHED_CHILD_STATUS */ /**************************************************************************** * Name: nxtask_groupexit * * Description: * Mark that the final thread of a child task group as exited. * ****************************************************************************/ #ifdef CONFIG_SCHED_CHILD_STATUS static inline void nxtask_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_find_child(group, getpid()); if (child) { /* Mark that all members of the child task group has exited */ child->ch_flags |= CHILD_FLAG_EXITED; } } } #else # define nxtask_groupexit(group) #endif /* CONFIG_SCHED_CHILD_STATUS */ /**************************************************************************** * Name: nxtask_sigchild * * Description: * Send the SIGCHLD signal to the parent thread * ****************************************************************************/ #ifdef CONFIG_SCHED_HAVE_PARENT #ifdef HAVE_GROUP_MEMBERS static inline void nxtask_sigchild(pid_t ppid, 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_findbypid(ppid); 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_ppid = INVALID_PROCESS_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 { nxtask_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 */ nxtask_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; info.si_pid = chgrp->tg_pid; info.si_status = status; /* Send the signal to one thread in the group */ group_signal(pgrp, &info); } } #else /* HAVE_GROUP_MEMBERS */ static inline void nxtask_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 */ nxtask_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; info.si_pid = ctcb->group->tg_pid; 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. */ nxsig_tcbdispatch(ptcb, &info); } } #endif /* HAVE_GROUP_MEMBERS */ #else /* CONFIG_SCHED_HAVE_PARENT */ # define nxtask_sigchild(x,ctcb,status) #endif /* CONFIG_SCHED_HAVE_PARENT */ /**************************************************************************** * Name: nxtask_signalparent * * Description: * Send the SIGCHLD signal to the parent task group * ****************************************************************************/ #ifdef CONFIG_SCHED_HAVE_PARENT static inline void nxtask_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 */ nxtask_sigchild(ctcb->group->tg_ppid, 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 nxtask_signalparent. */ ptcb = nxsched_get_tcb(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. NOTE that the * SIGCHLD signal is only sent once either (1) if this is the final thread * of the task group that is exiting (HAVE_GROUP_MEMBERS) or (2) if the * main thread of the group is exiting (!HAVE_GROUP_MEMBERS). */ nxtask_sigchild(ptcb, ctcb, status); sched_unlock(); #endif } #else # define nxtask_signalparent(ctcb,status) #endif /**************************************************************************** * Name: nxtask_exitwakeup * * Description: * Wakeup any tasks waiting for this task to exit * ****************************************************************************/ #if defined(CONFIG_SCHED_WAITPID) && !defined(CONFIG_SCHED_HAVE_PARENT) static inline void nxtask_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 != NULL) { *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; group->tg_waitflags = 0; while (group->tg_exitsem.semcount < 0) { /* Wake up the thread */ nxsem_post(&group->tg_exitsem); } } } } #else # define nxtask_exitwakeup(tcb, status) #endif /**************************************************************************** * Name: nxtask_flushstreams * * Description: * Flush all streams when the final thread of a group exits. * ****************************************************************************/ #ifdef CONFIG_FILE_STREAM static inline void nxtask_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) { #ifdef CONFIG_MM_KERNEL_HEAP lib_flushall(tcb->group->tg_streamlist); #else lib_flushall(&tcb->group->tg_streamlist); #endif } } #else # define nxtask_flushstreams(tcb) #endif /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: nxtask_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 nxtask_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 * nxtask_terminate() via _exit(). In that case, we must be careful to do * nothing that can cause the cause the thread to block. * ****************************************************************************/ void nxtask_exithook(FAR struct tcb_s *tcb, int status, bool nonblocking) { /* Under certain conditions, nxtask_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; } #ifdef CONFIG_CANCELLATION_POINTS /* Mark the task as non-cancelable to avoid additional calls to exit() * due to any cancellation point logic that might get kicked off by * actions taken during exit processing. */ tcb->flags |= TCB_FLAG_NONCANCELABLE; tcb->flags &= ~TCB_FLAG_CANCEL_PENDING; tcb->cpcount = 0; #endif if (!nonblocking) { /* 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 non-blocking == true * only when called through _exit(). _exit() behavior does not * require that the streams be flushed */ nxtask_flushstreams(tcb); } /* If the task was terminated by another task, it may be in an unknown * state. Make some feeble effort to recover the state. */ nxtask_recover(tcb); /* NOTE: signal handling needs to be done in a criticl section */ #ifdef CONFIG_SMP irqstate_t flags = enter_critical_section(); #endif /* Send the SIGCHLD signal to the parent task group */ nxtask_signalparent(tcb, status); /* Wakeup any tasks waiting for this task to exit */ nxtask_exitwakeup(tcb, status); /* Leave the task group. Perhaps discarding any un-reaped child * status (no zombies here!) */ group_leave(tcb); /* Deallocate anything left in the TCB's queues */ nxsig_cleanup(tcb); /* Deallocate Signal lists */ #ifdef CONFIG_SMP leave_critical_section(flags); #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; }