1 files changed, 441 insertions, 0 deletions
diff --git a/nuttx/sched/group_childstatus.c b/nuttx/sched/group_childstatus.c
new file mode 100644
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+++ b/nuttx/sched/group_childstatus.c
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+/*****************************************************************************
+ * sched/group_childstatus.c
+ *
+ *   Copyright (C) 2013 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 <sched.h>
+#include <errno.h>
+#include <debug.h>
+
+#include "os_internal.h"
+#include "group_internal.h"
+
+#if defined(CONFIG_SCHED_HAVE_PARENT) && defined(CONFIG_SCHED_CHILD_STATUS)
+
+/*****************************************************************************
+ * Pre-processor Definitions
+ *****************************************************************************/
+/* Note that there cannot be more that CONFIG_MAX_TASKS tasks in total.
+ * However, the number of child status structures may need to be significantly
+ * larger because this number includes the maximum number of tasks that are
+ * running PLUS the number of tasks that have exit'ed without having their
+ * exit status reaped (via wait(), waitid(), or waitpid()).
+ *
+ * Obviously, if tasks spawn children indefinitely and never have the exit
+ * status reaped, then you have a memory leak!
+ */
+
+#if !defined(CONFIG_PREALLOC_CHILDSTATUS) || CONFIG_PREALLOC_CHILDSTATUS == 0
+#  undef  CONFIG_PREALLOC_CHILDSTATUS
+#  define CONFIG_PREALLOC_CHILDSTATUS (2*CONFIG_MAX_TASKS)
+#endif
+
+#ifndef CONFIG_DEBUG
+#  undef CONFIG_DEBUG_CHILDSTATUS
+#endif
+
+/*****************************************************************************
+ * Private Types
+ *****************************************************************************/
+/* Globals are maintained in a structure to minimize name collisions. */
+
+struct child_pool_s
+{
+  struct child_status_s alloc[CONFIG_PREALLOC_CHILDSTATUS];
+  FAR struct child_status_s *freelist;
+};
+
+/*****************************************************************************
+ * Private Data
+ *****************************************************************************/
+
+static struct child_pool_s g_child_pool;
+
+/*****************************************************************************
+ * Private Functions
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Name: group_dumpchildren
+ *
+ * Description:
+ *   Dump all of the children when the part TCB list is modified.
+ *
+ * Parameters:
+ *   group - The task group containing the child status.
+ *
+ * Return Value:
+ *   None.
+ *
+ * Assumptions:
+ *   Called early in initialization.  No special precautions are required.
+ *
+ *****************************************************************************/
+
+#ifdef CONFIG_DEBUG_CHILDSTATUS
+static void group_dumpchildren(FAR struct task_group_s *group,
+                               FAR const char *msg)
+{
+  FAR struct child_status_s *child;
+  int i;
+
+  dbg("Task group=%p: %s\n", group, msg);
+  for (i = 0, child = group->tg_children; child; i++, child = child->flink)
+    {
+      dbg("  %d. ch_flags=%02x ch_pid=%d ch_status=%d\n",
+          i, child->ch_flags, child->ch_pid, child->ch_status);
+    }
+}
+#else
+#  define group_dumpchildren(t,m)
+#endif
+
+/*****************************************************************************
+ * Public Functions
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Name: task_initialize
+ *
+ * Description:
+ *   Initialize task related status.  At present, this includes only the
+ *   initialize of the child status pool.
+ *
+ * Parameters:
+ *   None.
+ *
+ * Return Value:
+ *   None.
+ *
+ * Assumptions:
+ *   Called early in initialization.  No special precautions are required.
+ *
+ *****************************************************************************/
+
+void task_initialize(void)
+{
+  FAR struct child_status_s *curr;
+  FAR struct child_status_s *prev;
+  int i;
+
+  /* Save all of the child status structures in a free list */
+
+  prev = &g_child_pool.alloc[0];
+  g_child_pool.freelist = prev;
+  for (i = 0; i < CONFIG_PREALLOC_CHILDSTATUS; i++)
+    {
+      curr        = &g_child_pool.alloc[i];
+      prev->flink = curr;
+      prev        = curr;
+    }
+}
+
+/*****************************************************************************
+ * Name: group_allocchild
+ *
+ * Description:
+ *   Allocate a child status structure by removing the next entry from a
+ *   free list.
+ *
+ * Parameters:
+ *   None.
+ *
+ * Return Value:
+ *   On success, a non-NULL pointer to a child status structure.  NULL is
+ *   returned if there are no remaining, pre-allocated child status structures.
+ *
+ * Assumptions:
+ *   Called during task creation in a safe context.  No special precautions
+ *   are required here.
+ *
+ *****************************************************************************/
+
+FAR struct child_status_s *group_allocchild(void)
+{
+  FAR struct child_status_s *ret;
+
+  /* Return the status block at the head of the free list */
+
+  ret = g_child_pool.freelist;
+  if (ret)
+    {
+      g_child_pool.freelist = ret->flink;
+      ret->flink            = NULL;
+    }
+
+  return ret;
+}
+
+/*****************************************************************************
+ * Name: group_freechild
+ *
+ * Description:
+ *   Release a child status structure by returning it to a free list.
+ *
+ * Parameters:
+ *   status - The child status structure to be freed.
+ *
+ * Return Value:
+ *   None.
+ *
+ * Assumptions:
+ *   Called during task creation in a safe context.  No special precautions
+ *   are required here.
+ *
+ *****************************************************************************/
+
+void group_freechild(FAR struct child_status_s *child)
+{
+  /* Return the child status structure to the free list  */
+
+  if (child)
+    {
+      child->flink          = g_child_pool.freelist;
+      g_child_pool.freelist = child;
+    }
+}
+
+/*****************************************************************************
+ * Name: group_addchild
+ *
+ * Description:
+ *   Add a child status structure in the given TCB.
+ *
+ * Parameters:
+ *   group  - The task group for the child status.
+ *   child  - The structure to be added
+ *
+ * Return Value:
+ *   N
+ *
+ * Assumptions:
+ *   Called during task creation processing in a safe context.  No special
+ *   precautions are required here.
+ *
+ *****************************************************************************/
+
+void group_addchild(FAR struct task_group_s *group,
+                   FAR struct child_status_s *child)
+{
+  /* Add the entry into the TCB list of children */
+
+  child->flink  = group->tg_children;
+  group->tg_children = child;
+
+  group_dumpchildren(group, "group_addchild");
+}
+
+/*****************************************************************************
+ * Name: group_findchild
+ *
+ * Description:
+ *   Find a child status structure in the given task group.  A reference to
+ *   the child structure is returned, but the child remains the the group's
+ *   list of children.
+ *
+ * Parameters:
+ *   group - The ID of the parent task group to containing the child status.
+ *   pid - The ID of the child to find.
+ *
+ * Return Value:
+ *   On success, a non-NULL pointer to a child status structure.  NULL is
+ *   returned if there is child status structure for that pid in the TCB.
+ *
+ * Assumptions:
+ *   Called during SIGCHLD processing in a safe context.  No special precautions
+ *   are required here.
+ *
+ *****************************************************************************/
+
+FAR struct child_status_s *group_findchild(FAR struct task_group_s *group,
+                                           pid_t pid)
+{
+  FAR struct child_status_s *child;
+
+  DEBUGASSERT(group);
+
+  /* Find the status structure with the matching PID  */
+
+  for (child = group->tg_children; child; child = child->flink)
+    {
+      if (child->ch_pid == pid)
+        {
+          return child;
+        }
+    }
+
+  return NULL;
+}
+
+/*****************************************************************************
+ * Name: group_exitchild
+ *
+ * Description:
+ *   Search for any child that has exitted.
+ *
+ * Parameters:
+ *   tcb - The TCB of the parent task to containing the child status.
+ *
+ * Return Value:
+ *   On success, a non-NULL pointer to a child status structure for the
+ *   exited child.  NULL is returned if not child has exited.
+ *
+ * Assumptions:
+ *   Called during SIGCHLD processing in a safe context.  No special precautions
+ *   are required here.
+ *
+ *****************************************************************************/
+
+FAR struct child_status_s *group_exitchild(FAR struct task_group_s *group)
+{
+  FAR struct child_status_s *child;
+
+  /* Find the status structure of any child task that has exitted. */
+
+  for (child = group->tg_children; child; child = child->flink)
+    {
+      if ((child->ch_flags & CHILD_FLAG_EXITED) != 0)
+        {
+          return child;
+        }
+    }
+
+  return NULL;
+}
+
+/*****************************************************************************
+ * Name: group_removechild
+ *
+ * Description:
+ *   Remove one child structure from a task group.  The child is removed, but
+ *   is not yet freed.  group_freechild must be called in order to free the
+ *   child status structure.
+ *
+ * Parameters:
+ *   group - The task group containing the child status.
+ *   pid - The ID of the child to find.
+ *
+ * Return Value:
+ *   On success, a non-NULL pointer to a child status structure.  NULL is
+ *   returned if there is child status structure for that pid in the TCB.
+ *
+ * Assumptions:
+ *   Called during SIGCHLD processing in a safe context.  No special precautions
+ *   are required here.
+ *
+ *****************************************************************************/
+
+FAR struct child_status_s *group_removechild(FAR struct task_group_s *group,
+                                             pid_t pid)
+{
+  FAR struct child_status_s *curr;
+  FAR struct child_status_s *prev;
+
+  DEBUGASSERT(group);
+
+  /* Find the status structure with the matching PID */
+
+  for (prev = NULL, curr = group->tg_children;
+       curr;
+       prev = curr, curr = curr->flink)
+    {
+      if (curr->ch_pid == pid)
+        {
+          break;
+        }
+    }
+
+  /* Did we find it?  If so, remove it from the group. */
+
+  if (curr)
+    {
+      /* Do we remove it from mid-list?  Or from the head of the list? */
+
+      if (prev)
+        {
+          prev->flink = curr->flink;
+        }
+      else
+        {
+          group->tg_children = curr->flink;
+        }
+
+      curr->flink = NULL;
+      group_dumpchildren(group, "group_removechild");
+    }
+ 
+  return curr;
+}
+
+/*****************************************************************************
+ * Name: group_removechildren
+ *
+ * Description:
+ *   Remove and free all child structure from the task group.
+ *
+ * Parameters:
+ *   group - The task group containing the child status.
+ *
+ * Return Value:
+ *   None.
+ *
+ * Assumptions:
+ *   Called during task exit processing in a safe context.  No special
+ *   precautions are required here.
+ *
+ *****************************************************************************/
+
+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");
+}
+
+#endif /* CONFIG_SCHED_HAVE_PARENT && CONFIG_SCHED_CHILD_STATUS */