1 files changed, 163 insertions, 0 deletions
diff --git a/nuttx/sched/task_reparent.c b/nuttx/sched/task_reparent.c
new file mode 100644
index 000000000..28d371bf1
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+++ b/nuttx/sched/task_reparent.c
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+/*****************************************************************************
+ * sched/task_reparent.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 <errno.h>
+
+#include "os_internal.h"
+
+#ifdef CONFIG_SCHED_HAVE_PARENT
+
+/*****************************************************************************
+ * Private Functions
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Public Functions
+ *****************************************************************************/
+
+/*****************************************************************************
+ * Name: task_reparent
+ *
+ * Description:
+ *   Change the parent of a task.
+ *
+ * Parameters:
+ *   ppid - PID of the new parent task (0 for grandparent, i.e. the parent
+ *     of the current parent task)
+ *   chpid  - PID of the child to be reparented.
+ *
+ * Return Value:
+ *   0 (OK) on success; A negated errno value on failure.
+ *
+ *****************************************************************************/
+
+int task_reparent(pid_t ppid, pid_t chpid)
+{
+#ifdef CONFIG_SCHED_CHILD_STATUS
+  FAR struct child_status_s *child;
+#endif
+  _TCB *ptcb;
+  _TCB *chtcb;
+  _TCB *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->parent;
+
+  /* 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->parent;
+    }
+  
+  /* 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->parent = 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 = task_removechild(otcb, chpid);
+  if (child)
+    {
+      /* Add the child status entry to the new parent TCB */
+
+      task_addchild(ptcb, child);
+      ret = OK;
+    }
+  else
+    {
+      ret = -ENOENT;
+    }
+#else
+  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
+  
+errout_with_ints:
+  irqrestore(flags);
+  return ret;  
+}
+
+#endif /* CONFIG_SCHED_HAVE_PARENT */